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Jiang JZ, Qiao YB, Zhu XR, Gu QH, Lu JJ, Ye ZY, Xu L, Liu YY. Identification of Gαi3 as a promising molecular oncotarget of pancreatic cancer. Cell Death Dis 2024; 15:699. [PMID: 39349432 PMCID: PMC11442978 DOI: 10.1038/s41419-024-07079-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 09/08/2024] [Accepted: 09/13/2024] [Indexed: 10/02/2024]
Abstract
The increasing mortality rate of pancreatic cancer globally necessitates the urgent identification for novel therapeutic targets. This study investigated the expression, functions, and mechanistic insight of G protein inhibitory subunit 3 (Gαi3) in pancreatic cancer. Bioinformatics analyses reveal that Gαi3 is overexpressed in human pancreatic cancer, correlating with poor prognosis, higher tumor grade, and advanced classification. Elevated Gαi3 levels are also confirmed in human pancreatic cancer tissues and primary/immortalized cancer cells. Gαi3 shRNA or knockout (KO) significantly reduced cell viability, proliferation, cell cycle progression, and mobility in primary/immortalized pancreatic cancer cells. Conversely, Gαi3 overexpression enhanced pancreatic cancer cell growth. RNA-sequencing and bioinformatics analyses of Gαi3-depleted cells indicated Gαi3's role in modulating the Akt-mTOR and PKA-Hippo-YAP pathways. Akt-S6 phosphorylation was decreased in Gαi3-depleted cells, but was increased with Gαi3 overexpression. Additionally, Gαi3 depletion elevated PKA activity and activated the Hippo pathway kinase LATS1/2, leading to YAP/TAZ inactivation, while Gαi3 overexpression exerted the opposite effects. There is an increased binding between Gαi3 promoter and the transcription factor TCF7L2 in pancreatic cancer tissues and cells. Gαi3 expression was significantly decreased following TCF7L2 silencing, but increased with TCF7L2 overexpression. In vivo, intratumoral injection of Gαi3 shRNA-expressing adeno-associated virus significantly inhibited subcutaneous pancreatic cancer xenografts growth in nude mice. A significant growth reduction was also observed in xenografts from Gαi3 knockout pancreatic cancer cells. Akt-mTOR inactivation and increased PKA activity coupled with YAP/TAZ inactivation were also detected in xenograft tumors upon Gαi3 depletion. Furthermore, bioinformatic analysis and multiplex immunohistochemistry (mIHC) staining on pancreatic cancer tissue microarrays showed a reduced proportion of M1-type macrophages and an increase in PD-L1 positive cells in Gαi3-high pancreatic cancer tissues. Collectively, these findings highlight Gαi3's critical role in promoting pancreatic cancer cell growth, potentially through the modulation of the Akt-mTOR and PKA-Hippo-YAP pathways and its influence on the immune landscape.
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Affiliation(s)
- Jian-Zhuo Jiang
- Clinical Research and Lab Center, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Yin-Biao Qiao
- General Surgery, Cancer Center, Department of Colorectal Surgery, Zhejiang Provincial People's Hospital, Hangzhou, China
| | - Xiao-Ren Zhu
- Department of Radiotherapy and Oncology, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Qian-Hui Gu
- Department of Radiotherapy and Oncology, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Jing-Jing Lu
- Department of Radiotherapy and Oncology, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Zhen-Yu Ye
- Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou, China.
| | - Lu Xu
- Department of general surgery, The first affiliated hospital of Soochow university, Suzhou, China.
| | - Yuan-Yuan Liu
- Clinical Research and Lab Center, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China.
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Elkahwagy DMAS, Kiriacos CJ, Mansour M. Logistic regression and other statistical tools in diagnostic biomarker studies. Clin Transl Oncol 2024; 26:2172-2180. [PMID: 38530558 PMCID: PMC11333519 DOI: 10.1007/s12094-024-03413-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 02/16/2024] [Indexed: 03/28/2024]
Abstract
A biomarker is a measured indicator of a variety of processes, and is often used as a clinical tool for the diagnosis of diseases. While the developmental process of biomarkers from lab to clinic is complex, initial exploratory stages often focus on characterizing the potential of biomarkers through utilizing various statistical methods that can be used to assess their discriminatory performance, establish an appropriate cut-off that transforms continuous data to apt binary responses of confirming or excluding a diagnosis, or establish a robust association when tested against confounders. This review aims to provide a gentle introduction to the most common tools found in diagnostic biomarker studies used to assess the performance of biomarkers with an emphasis on logistic regression.
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Affiliation(s)
| | - Caroline Joseph Kiriacos
- Pharmaceutical Biology Department, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo, 11835, Egypt
| | - Manar Mansour
- Pharmaceutical Biology Department, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo, 11835, Egypt
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3
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Frosch ZAK, Hasler J, Handorf E, DuBois T, Bleicher RJ, Edelman MJ, Geynisman DM, Hall MJ, Fang CY, Lynch SM. Development of a Multilevel Model to Identify Patients at Risk for Delay in Starting Cancer Treatment. JAMA Netw Open 2023; 6:e2328712. [PMID: 37578796 PMCID: PMC10425824 DOI: 10.1001/jamanetworkopen.2023.28712] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 07/05/2023] [Indexed: 08/15/2023] Open
Abstract
Importance Delays in starting cancer treatment disproportionately affect vulnerable populations and can influence patients' experience and outcomes. Machine learning algorithms incorporating electronic health record (EHR) data and neighborhood-level social determinants of health (SDOH) measures may identify at-risk patients. Objective To develop and validate a machine learning model for estimating the probability of a treatment delay using multilevel data sources. Design, Setting, and Participants This cohort study evaluated 4 different machine learning approaches for estimating the likelihood of a treatment delay greater than 60 days (group least absolute shrinkage and selection operator [LASSO], bayesian additive regression tree, gradient boosting, and random forest). Criteria for selecting between approaches were discrimination, calibration, and interpretability/simplicity. The multilevel data set included clinical, demographic, and neighborhood-level census data derived from the EHR, cancer registry, and American Community Survey. Patients with invasive breast, lung, colorectal, bladder, or kidney cancer diagnosed from 2013 to 2019 and treated at a comprehensive cancer center were included. Data analysis was performed from January 2022 to June 2023. Exposures Variables included demographics, cancer characteristics, comorbidities, laboratory values, imaging orders, and neighborhood variables. Main Outcomes and Measures The outcome estimated by machine learning models was likelihood of a delay greater than 60 days between cancer diagnosis and treatment initiation. The primary metric used to evaluate model performance was area under the receiver operating characteristic curve (AUC-ROC). Results A total of 6409 patients were included (mean [SD] age, 62.8 [12.5] years; 4321 [67.4%] female; 2576 [40.2%] with breast cancer, 1738 [27.1%] with lung cancer, and 1059 [16.5%] with kidney cancer). A total of 1621 (25.3%) experienced a delay greater than 60 days. The selected group LASSO model had an AUC-ROC of 0.713 (95% CI, 0.679-0.745). Lower likelihood of delay was seen with diagnosis at the treating institution; first malignant neoplasm; Asian or Pacific Islander or White race; private insurance; and lacking comorbidities. Greater likelihood of delay was seen at the extremes of neighborhood deprivation. Model performance (AUC-ROC) was lower in Black patients, patients with race and ethnicity other than non-Hispanic White, and those living in the most disadvantaged neighborhoods. Though the model selected neighborhood SDOH variables as contributing variables, performance was similar when fit with and without these variables. Conclusions and Relevance In this cohort study, a machine learning model incorporating EHR and SDOH data was able to estimate the likelihood of delays in starting cancer therapy. Future work should focus on additional ways to incorporate SDOH data to improve model performance, particularly in vulnerable populations.
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Affiliation(s)
- Zachary A. K. Frosch
- Department of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- Cancer Prevention and Control Research Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Jill Hasler
- Department of Biostatistics, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Elizabeth Handorf
- Cancer Prevention and Control Research Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- Department of Biostatistics, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Tesla DuBois
- Cancer Prevention and Control Research Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Richard J. Bleicher
- Department of Surgical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Martin J. Edelman
- Department of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Daniel M. Geynisman
- Department of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Michael J. Hall
- Department of Hematology/Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
- Cancer Prevention and Control Research Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Carolyn Y. Fang
- Cancer Prevention and Control Research Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Shannon M. Lynch
- Cancer Prevention and Control Research Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
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Exact Probability Distribution for the ROC Area under Curve. Cancers (Basel) 2023; 15:cancers15061788. [PMID: 36980674 PMCID: PMC10046879 DOI: 10.3390/cancers15061788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/03/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
The Receiver Operating Characteristic (ROC) is a de facto standard for determining the accuracy of in vitro diagnostic (IVD) medical devices, and thus the exactness in its probability distribution is crucial toward accurate statistical inference. We show the exact probability distribution of the ROC AUC-value, hence exact critical values and p-values are readily obtained. Because the exact calculations are computationally intense, we demonstrate a method of geometric interpolation, which is exact in a special case but generally an approximation, vastly increasing computational speeds. The method is illustrated through open access data, demonstrating superiority of 26 composite biomarkers relative to a predicate device. Especially under correction for testing of multiple hypotheses, traditional asymptotic approximations are encumbered by considerable imprecision, adversely affecting IVD device development. The ability to obtain exact p-values will allow more efficient IVD device development.
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Chicco D, Jurman G. The Matthews correlation coefficient (MCC) should replace the ROC AUC as the standard metric for assessing binary classification. BioData Min 2023; 16:4. [PMID: 36800973 PMCID: PMC9938573 DOI: 10.1186/s13040-023-00322-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 02/01/2023] [Indexed: 02/19/2023] Open
Abstract
Binary classification is a common task for which machine learning and computational statistics are used, and the area under the receiver operating characteristic curve (ROC AUC) has become the common standard metric to evaluate binary classifications in most scientific fields. The ROC curve has true positive rate (also called sensitivity or recall) on the y axis and false positive rate on the x axis, and the ROC AUC can range from 0 (worst result) to 1 (perfect result). The ROC AUC, however, has several flaws and drawbacks. This score is generated including predictions that obtained insufficient sensitivity and specificity, and moreover it does not say anything about positive predictive value (also known as precision) nor negative predictive value (NPV) obtained by the classifier, therefore potentially generating inflated overoptimistic results. Since it is common to include ROC AUC alone without precision and negative predictive value, a researcher might erroneously conclude that their classification was successful. Furthermore, a given point in the ROC space does not identify a single confusion matrix nor a group of matrices sharing the same MCC value. Indeed, a given (sensitivity, specificity) pair can cover a broad MCC range, which casts doubts on the reliability of ROC AUC as a performance measure. In contrast, the Matthews correlation coefficient (MCC) generates a high score in its [Formula: see text] interval only if the classifier scored a high value for all the four basic rates of the confusion matrix: sensitivity, specificity, precision, and negative predictive value. A high MCC (for example, MCC [Formula: see text] 0.9), moreover, always corresponds to a high ROC AUC, and not vice versa. In this short study, we explain why the Matthews correlation coefficient should replace the ROC AUC as standard statistic in all the scientific studies involving a binary classification, in all scientific fields.
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Affiliation(s)
- Davide Chicco
- Institute of Health Policy Management and Evaluation, University of Toronto, 155 College Street, M5T 3M7 Toronto, Ontario Canada
| | - Giuseppe Jurman
- Data Science for Health Unit, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, Trento, Italy
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The Role of procollagen type 1 amino-terminal propertied (P1NP) Cytochrome P450 (CYPs) and Osteoprotegerin (OPG) as Potential Bone function markers in Prostate Cancer Bone Metastasis. REV ROMANA MED LAB 2023. [DOI: 10.2478/rrlm-2023-0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Abstract
Background: Procollagen type I amino-terminal propeptide (PINP) is often present during osteoblast development and could be a biomarker of early bone development. Osteoprotegerin (OPG) may protect tumor cells from apoptosis. Cytochrome P450 enzymes help tumor development and treatment (CYPs). Cytochrome P450 activates and deactivates anticancer drugs and procarcinogens.
Objective: The study examined the amounts of a diagnostic marker of bone formation, the amino terminal propeptide of type I procollagen (PINP), Osteoprotegerin (OPG), and P450, in prostate cancer patients at different stages and its ability to detect osteoblastic metastases.
Methods: ELISA was used to measure PINP, OPG, and P450 levels in 30 prostate cancer patients. (n = 32) and healthy men’s serum (n = 36).
Results: Prostate cancer patients had higher blood levels of PINP, OPG, and P450 than healthy persons (301.3±134.9, 980±467.2, and 84.2±28.4 pg/mL, respectively). Compared to I+II prostate cancer patients, III+IV patients showed higher serum PINP, OPG, and P450 levels (P 0.001). OPG, P450, and PINP had statistically significant Area under the ROC curve (0.9467, P= 0.0001, 0.91, P= 0.0001, and 0.6977, P= 0.4035) in prostate cancer patients.
Conclusions: Metastatic prostate cancer patients had greater PINP, OPG, and P450 levels, according to our findings. PINP, OPG, and P450 levels may affect prostate cancer progression. These findings imply that serum PINP, OPG, and P450 levels may predict and diagnose prostate cancer.
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Language Semantics Interpretation with an Interaction-Based Recurrent Neural Network. MACHINE LEARNING AND KNOWLEDGE EXTRACTION 2021. [DOI: 10.3390/make3040046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Text classification is a fundamental language task in Natural Language Processing. A variety of sequential models are capable of making good predictions, yet there is a lack of connection between language semantics and prediction results. This paper proposes a novel influence score (I-score), a greedy search algorithm, called Backward Dropping Algorithm (BDA), and a novel feature engineering technique called the “dagger technique”. First, the paper proposes to use the novel influence score (I-score) to detect and search for the important language semantics in text documents that are useful for making good predictions in text classification tasks. Next, a greedy search algorithm, called the Backward Dropping Algorithm, is proposed to handle long-term dependencies in the dataset. Moreover, the paper proposes a novel engineering technique called the “dagger technique” that fully preserves the relationship between the explanatory variable and the response variable. The proposed techniques can be further generalized into any feed-forward Artificial Neural Networks (ANNs) and Convolutional Neural Networks (CNNs), and any neural network. A real-world application on the Internet Movie Database (IMDB) is used and the proposed methods are applied to improve prediction performance with an 81% error reduction compared to other popular peers if I-score and “dagger technique” are not implemented.
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Pugh SL, Torres-Saavedra PA. Fundamental Statistical Concepts in Clinical Trials and Diagnostic Testing. J Nucl Med 2021; 62:757-764. [PMID: 33608427 DOI: 10.2967/jnumed.120.245654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/27/2021] [Indexed: 11/16/2022] Open
Abstract
This article explores basic statistical concepts of clinical trial design and diagnostic testing, or how one starts with a question, formulates it into a hypothesis on which a clinical trial is then built, and integrates it with statistics and probability, such as determining the probability of rejecting the null hypothesis when it is actually true (type I error) and the probability of failing to reject the null hypothesis when it is false (type II error). There are a variety of tests for different types of data, and the appropriate test must be chosen for which the sample data meet the assumptions. Correcting type I error in the presence of multiple testing is needed to control the error's inflation. Within diagnostic testing, identifying false-positive and false-negative results is critical to understanding the performance of a test. These are used to determine the sensitivity and specificity of a test along with the test's negative predictive value and positive predictive value. These quantities, specifically sensitivity and specificity, are used to determine the accuracy of a diagnostic test using receiver-operating-characteristic curves. These concepts are briefly introduced to provide a basic understanding of clinical trial design and analysis, with references to allow the reader to explore various concepts at a more detailed level if desired.
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Affiliation(s)
- Stephanie L Pugh
- NRG Oncology Statistical and Data Management Center, American College of Radiology, Philadelphia, Pennsylvania
| | - Pedro A Torres-Saavedra
- NRG Oncology Statistical and Data Management Center, American College of Radiology, Philadelphia, Pennsylvania
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Baker SG, Kramer BS. Simple Methods for Evaluating 4 Types of Biomarkers: Surrogate Endpoint, Prognostic, Predictive, and Cancer Screening. Biomark Insights 2020; 15:1177271920946715. [PMID: 32821082 PMCID: PMC7412628 DOI: 10.1177/1177271920946715] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 07/06/2020] [Indexed: 11/16/2022] Open
Abstract
We review simple methods for evaluating 4 types of biomarkers. First, we discuss the evaluation of surrogate endpoint biomarkers (to shorten a randomized trial) using 2 statistical and 3 biological criteria. Second, we discuss the evaluation of prognostic biomarkers (to predict the risk of disease) by comparing data collection costs with the anticipated net benefit of risk prediction. Third, we discuss the evaluation of predictive markers (to search for a promising subgroup in a randomized trial) using a multivariate subpopulation treatment effect pattern plot involving a risk difference or responders-only benefit function. Fourth, we discuss the evaluation of cancer screening biomarkers (to predict cancer in asymptomatic persons) using methodology to substantially reduce the sample size with stored specimens.
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Affiliation(s)
- Stuart G Baker
- Biometry Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, MD, USA
| | - Barnett S Kramer
- Biometry Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, MD, USA
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Franco-Pereira AM, Nakas CT, Pardo MC. Biomarker assessment in ROC curve analysis using the length of the curve as an index of diagnostic accuracy: the binormal model framework. ASTA ADVANCES IN STATISTICAL ANALYSIS 2020. [DOI: 10.1007/s10182-020-00371-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Lee YCA, Al-Temimi M, Ying J, Muscat J, Olshan AF, Zevallos JP, Winn DM, Li G, Sturgis EM, Morgenstern H, Zhang ZF, Smith E, Kelsey K, McClean M, Vaughan TL, Lazarus P, Chen C, Schwartz SM, Gillison M, Schantz S, Yu GP, D'Souza G, Gross N, Monroe M, Kim J, Boffetta P, Hashibe M. Risk Prediction Models for Head and Neck Cancer in the US Population From the INHANCE Consortium. Am J Epidemiol 2020; 189:330-342. [PMID: 31781743 DOI: 10.1093/aje/kwz259] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 10/29/2019] [Accepted: 11/06/2019] [Indexed: 12/23/2022] Open
Abstract
Head and neck cancer (HNC) risk prediction models based on risk factor profiles have not yet been developed. We took advantage of the large database of the International Head and Neck Cancer Epidemiology (INHANCE) Consortium, including 14 US studies from 1981-2010, to develop HNC risk prediction models. Seventy percent of the data were used to develop the risk prediction models; the remaining 30% were used to validate the models. We used competing-risk models to calculate absolute risks. The predictors included age, sex, education, race/ethnicity, alcohol drinking intensity, cigarette smoking duration and intensity, and/or family history of HNC. The 20-year absolute risk of HNC was 7.61% for a 60-year-old woman who smoked more than 20 cigarettes per day for over 20 years, consumed 3 or more alcoholic drinks per day, was a high school graduate, had a family history of HNC, and was non-Hispanic white. The 20-year risk for men with a similar profile was 6.85%. The absolute risks of oropharyngeal and hypopharyngeal cancers were generally lower than those of oral cavity and laryngeal cancers. Statistics for the area under the receiver operating characteristic curve (AUC) were 0.70 or higher, except for oropharyngeal cancer in men. This HNC risk prediction model may be useful in promoting healthier behaviors such as smoking cessation or in aiding persons with a family history of HNC to evaluate their risks.
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Ahmadian R, Ercan I, Sigirli D, Yildiz A. Combining binary and continuous biomarkers by maximizing the area under the receiver operating characteristic curve. COMMUN STAT-SIMUL C 2020. [DOI: 10.1080/03610918.2020.1742354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Robab Ahmadian
- Department of Biostatistics, Uludag University, Bursa, Turkey
| | - Ilker Ercan
- Department of Biostatistics, Uludag University, Bursa, Turkey
| | - Deniz Sigirli
- Department of Biostatistics, Uludag University, Bursa, Turkey
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Chiu LY, Chen A. A Variance-reduction Approach to Detection of the Thyroid-nodule Boundary on Ultrasound Images. ULTRASONIC IMAGING 2019; 41:206-230. [PMID: 30990130 DOI: 10.1177/0161734619839648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
To perform computer-aided diagnosis of the thyroid nodules on ultrasound images, the location and boundary of nodules should be clearly defined. However, the identification of thyroid nodule boundary is a difficult issue due to the biological characteristics of the nodules, the physics and quality of ultrasound imaging, and the subjective factors and operating conditions of the operator. In this study, we propose a novel and semiautomatic method for detecting the boundary of thyroid nodule based on the Variance-Reduction (V-R) statistics without image preprocessing. The region of interest (ROI) is first automatically generated according to the initial inputs of the nodule's major and minor axes. The boundary candidate pixel points are then extracted by using the V-R statistics from the grayscale values of all pixel points in the ROI. Three filtering methods are further applied to eliminate the outlier pixel points to ensure that the remaining candidate pixel points are located on the nodule boundary. Finally, the remaining pixel points are smoothened and linked together to form the final boundary. The proposed method is validated with ultrasound images of 538 thyroid nodules, with manual delineation by experienced radiologist as gold standard. The effectiveness is evaluated and compared with previous publications using boundary error metrics and overlapping area metrics with the same data set. The results show that the normalized average mean boundary error is 1.02%, the true positive overlapping area ratio achieves 93.66% and false positive overlapping area ratio is limited to 7.68%. In conclusion, our proposed method is reliable and effective in detecting thyroid nodule boundary on ultrasound images.
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Affiliation(s)
- Ling-Ying Chiu
- 1 Institute of Industrial Engineering, National Taiwan University, Taipei
| | - Argon Chen
- 1 Institute of Industrial Engineering, National Taiwan University, Taipei
- 2 Department of Mechanical Engineering, National Taiwan University, Taipei
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Silva C, Perestrelo R, Silva P, Capelinha F, Tomás H, Câmara JS. Volatomic pattern of breast cancer and cancer-free tissues as a powerful strategy to identify potential biomarkers. Analyst 2019; 144:4153-4161. [PMID: 31144689 DOI: 10.1039/c9an00263d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Breast cancer (BC), ranked as the fifth amongst all cancers, remains at the top of women's cancers worldwide followed by colorectal, lung, cervix, and stomach cancers. The main handicap of most of the screening/diagnostic methods is based on their low sensitivity and specificity and the invasive behavior of most sampling procedures. The aim of this study was to establish the volatomic pattern of BC and cancer-free (CF) tissues (n = 30) from the same patients, as a powerful tool to identify a set of volatile organic metabolite (VOM) potential BC biomarkers which might be used together or complement with the traditional BC diagnostics strategies, through the integration of chromatographic data, obtained by solid-phase microextraction followed by gas chromatography-mass spectrometry (SPME/GC-qMS), with chemometric tools. A total of four metabolites: limonene, decanoic acid, acetic acid and furfural presented the highest contribution towards discrimination of BC and CF tissues (VIP > 1, p < 0.05). The discrimination efficiency and accuracy of BC tissue metabolites was ascertained by ROC curve analysis that allowed the identification of some metabolites with high sensitivity and specificity. The results obtained with this approach suggest the possibility of identifying endogenous metabolites as a platform to find potential BC biomarkers and pave the way to investigate the related metabolomic pathways in order to improve BC diagnostic tools. Moreover, deeper investigations could unravel novel mechanistic insights into the disease pathophysiology.
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Affiliation(s)
- Catarina Silva
- CQM, Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal
| | - Rosa Perestrelo
- CQM, Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal
| | - Pedro Silva
- CQM, Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal
| | - Filipa Capelinha
- SESARAM, EPE. Hospital Dr. Nélio Mendonça, Serviço de Anatomia Patológica, Avenida Luís de Camões, n° 57-9004-514 Funchal, Portugal.
| | - Helena Tomás
- CQM, Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal and Faculdade de Ciências Exatas e da Engenharia, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal
| | - José S Câmara
- CQM, Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal and Faculdade de Ciências Exatas e da Engenharia, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal
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15
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Smith AM, Christodouleas JP, Hwang WT. Understanding the predictive value of continuous markers for censored survival data using a likelihood ratio approach. BMC Med Res Methodol 2019; 19:108. [PMID: 31117940 PMCID: PMC6532165 DOI: 10.1186/s12874-019-0721-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 03/27/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The likelihood ratio function (LR), the ratio of conditional probabilities of obtaining a specific marker value among those with the event of interest over those without, provides an easily interpretable way to quantify the update of the risk prediction due to the knowledge of the marker value. The LR has been explored for both binary and continuous markers for binary events (e.g., diseased or not), however the use of the LR in censored data has not been fully explored. METHODS We extend the concept of LR to a time-dependent LR (TD-LR) for survival outcomes that are subject to censoring. Estimation for the TD-LR is done using Kaplan-Meier estimation and a univariate Cox proportional hazards (PH) model. A "scale invariant" approach based on marker quantiles is provided to allow comparison of predictive values between markers with different scales. Relationships to time-dependent receiver-operator characteristic (ROC) curves, area under the curve (AUC), and optimal cut-off values are considered. RESULTS The proposed methods were applied to data from a bladder cancer clinical trial to determine whether the neutrophil-to-lymphocyte ratio (NLR) is a valuable biomarker for predicting overall survival following surgery or combined chemotherapy and surgery. The TD-LR method yielded results consistent with the original findings while providing an easily interpretable three-dimensional surface display of how NLR related to the likelihood of event in the trial data. CONCLUSIONS The TD-LR provides a more nuanced understanding of the relationship between continuous markers and the likelihood of events in censored survival data. This method also allows more straightforward communication with a clinical audience through graphical presentation.
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Affiliation(s)
- Andrew M. Smith
- Department of Biostatistics, Epidemiology, and Informatics, 610 Blockley Hall 423 Guardian Drive, Philadelphia, 19104 USA
- 3250 Whitfield Ave Apt 211, Cincinnati, OH, 45220 USA
| | | | - Wei-Ting Hwang
- Department of Biostatistics, Epidemiology, and Informatics, 610 Blockley Hall 423 Guardian Drive, Philadelphia, 19104 USA
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Silva CL, Perestrelo R, Silva P, Tomás H, Câmara JS. Implementing a central composite design for the optimization of solid phase microextraction to establish the urinary volatomic expression: a first approach for breast cancer. Metabolomics 2019; 15:64. [PMID: 30997581 DOI: 10.1007/s11306-019-1525-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/10/2019] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Breast cancer (BC) is positioned as the second among all cancers remaining at the top of women´s diseases worldwide followed by colorectum, lung, cervix, and thyroid cancers. The main drawback of most the screening/diagnostic methods is their low sensitivity/specificity and in some cases the invasive procedure required to obtain the samples. OBJECTIVES On the present investigation, we report a statistical design was to evaluate by central composite design the influence towards the optimization of the most significant variables of solid-phase microextraction (SPME) procedure for the isolation of volatile organic metabolites (VOMs) from urine of BC patients (N = 31) and healthy individuals (CTL; N = 40). The establishment of the urinary volatomic composition, through gas chromatography-mass spectrometry (GC-MS) analysis, can boost the identification of volatile organic metabolites (VOMs) potential BC biomarkers useful to be used together or to complement the current BC diagnostics tools. Better early detection methods are needed to improve the outcomes of patients with BC. METHODS Several combinations of experiments were considered with a central composite design (CCD) of response surface methodology (RSM) for the urinary volatomic pattern. Three-level three-factor CCD was employed assessing the most important extraction-influencing variables-fiber coating, NaCl amount, extraction time and temperature. The optimal conditions were achieved using a carboxen/polydimethylsiloxane fiber with 15% (w/v) NaCl during 75 min at 50 °C. RESULTS A total of ten VOMs belonging to sulfur compounds, terpenoids and carbonyl compounds presented the highest contribution towards discrimination of BC patients from CTL (variable importance in projection (VIP) > 1, p < 0.05). The discrimination efficiency and accuracy of urinary metabolites was ascertained by receiver operating characteristic (ROC) curve analysis that allowed the identification of some metabolites with highest sensitivity and specificity to discriminate the groups. CONCLUSIONS The results obtained with this approach suggest the possibility to identify endogenous metabolites as a platform to discovery potential BC biomarkers and paves a way to explore the related metabolomic pathways in order to improve BC diagnostic tools.
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Affiliation(s)
- Catarina L Silva
- CQM-Centro de Química da Madeira, Universidade da Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal
| | - Rosa Perestrelo
- CQM-Centro de Química da Madeira, Universidade da Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal
| | - Pedro Silva
- CQM-Centro de Química da Madeira, Universidade da Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal
| | - Helena Tomás
- CQM-Centro de Química da Madeira, Universidade da Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal
- Faculdade de Ciências Exactas e Engenharia da Universidade da Madeira, Universidade da Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal
| | - José S Câmara
- CQM-Centro de Química da Madeira, Universidade da Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal.
- Faculdade de Ciências Exactas e Engenharia da Universidade da Madeira, Universidade da Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal.
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17
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Paczesny S, Metzger J. Clinical Proteomics for Post-Hematopoeitic Stem Cell Transplantation Outcomes. Proteomics Clin Appl 2019; 13:e1800145. [PMID: 30307119 PMCID: PMC6440827 DOI: 10.1002/prca.201800145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 09/28/2018] [Indexed: 12/20/2022]
Abstract
Allogeneic hematopoietic stem cell transplantation (HSCT) is the most effective form of tumor immunotherapy available to date. However, while HSCT can induce beneficial graft-versus-leukemia (GVL) effect, the adverse effect of graft-versus-host disease (GVHD), which is closely linked to GVL, is the major source of morbidity and mortality following HSCT. Until recently, available diagnostic and staging tools frequently fail to identify those at higher risk of disease progression or death. Furthermore, there are shortcomings in the prediction of the need for therapeutic interventions or the response rates to different forms of therapy. The past decade has been characterized by an explosive evolution of proteomics technologies, largely due to important advances in high-throughput MS instruments and bioinformatics. Building on these opportunities, blood biomarkers have been identified and validated both as promising diagnostic tools, prognostic tools that risk-stratify patients before future occurrence of GVHD and as predictive tools for responsiveness to GVHD therapy and non-relapse mortality. These biomarkers might facilitate timely and selective therapeutic intervention. This review summarizes current information on clinical proteomics for GVHD as well as other complications following HSCT. Finally, it proposes future directions for the translation of clinical proteomics to discovery of new potential therapeutic targets to the development of drugs.
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Affiliation(s)
- Sophie Paczesny
- Department of Pediatrics, Department of Microbiology Immunology, and Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana, USA
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18
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Abstract
A receiver operating characteristic (ROC) curve is a graphical plot that illustrates the diagnostic ability of a binary classifier as a function of its discrimination threshold. This chapter is an overview on the use of ROC curves for microarray data. The notion of ROC curve and its motivation is introduced in Subheading 1. Relevant scientific contributions concerning the use of ROC curves for microarray data are briefly reviewed in Subheading 2. The special case with covariates is considered in Subheading 3. Two relevant aspects are reviewed in this section: the use of LASSO techniques for selecting and combining relevant markers and how to correct for multiple testing when a large number of markers are available. Finally, some conclusions are included.
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Affiliation(s)
- Ricardo Cao
- Research Group MODES, Department of Mathematics, CITIC and ITMATI, Universidade da Coruña, A Coruña, Spain.
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19
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Doherty M, Theodoratou E, Walsh I, Adamczyk B, Stöckmann H, Agakov F, Timofeeva M, Trbojević-Akmačić I, Vučković F, Duffy F, McManus CA, Farrington SM, Dunlop MG, Perola M, Lauc G, Campbell H, Rudd PM. Plasma N-glycans in colorectal cancer risk. Sci Rep 2018; 8:8655. [PMID: 29872119 PMCID: PMC5988698 DOI: 10.1038/s41598-018-26805-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 05/16/2018] [Indexed: 12/22/2022] Open
Abstract
Aberrant glycosylation has been associated with a number of diseases including cancer. Our aim was to elucidate changes in whole plasma N-glycosylation between colorectal cancer (CRC) cases and controls in one of the largest cohorts of its kind. A set of 633 CRC patients and 478 age and gender matched controls was analysed. Additionally, patients were stratified into four CRC stages. Moreover, N-glycan analysis was carried out in plasma of 40 patients collected prior to the initial diagnosis of CRC. Statistically significant differences were observed in the plasma N-glycome at all stages of CRC, this included a highly significant decrease in relation to the core fucosylated bi-antennary glycans F(6)A2G2 and F(6)A2G2S(6)1 (P < 0.0009). Stage 1 showed a unique biomarker signature compared to stages 2, 3 and 4. There were indications that at risk groups could be identified from the glycome (retrospective AUC = 0.77 and prospective AUC = 0.65). N-glycome biomarkers related to the pathogenic progress of the disease would be a considerable asset in a clinical setting and it could enable novel therapeutics to be developed to target the disease in patients at risk of progression.
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Affiliation(s)
- Margaret Doherty
- National Institute for Bioprocessing Research & Training, Dublin, Ireland.
- Institute of Technology Sligo, Department of Life Sciences, Sligo, Ireland.
| | - Evropi Theodoratou
- Centre for Global Health Research, Usher Institute for Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK
- Colon Cancer Genetics Group, Institute of Genetics and Molecular Medicine, University of Edinburgh and Medical Research Council Human Genetics Unit, Edinburgh, UK
| | - Ian Walsh
- Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), 20 Biopolis Way, #06-01 Centros, Singapore, 138668, Singapore
| | - Barbara Adamczyk
- National Institute for Bioprocessing Research & Training, Dublin, Ireland
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Henning Stöckmann
- National Institute for Bioprocessing Research & Training, Dublin, Ireland
| | - Felix Agakov
- Pharmatics Limited, Edinburgh Bioquarter, 9 Little France Road, Edinburgh, UK
| | - Maria Timofeeva
- Colon Cancer Genetics Group, Institute of Genetics and Molecular Medicine, University of Edinburgh and Medical Research Council Human Genetics Unit, Edinburgh, UK
| | | | | | - Fergal Duffy
- National Institute for Bioprocessing Research & Training, Dublin, Ireland
| | - Ciara A McManus
- National Institute for Bioprocessing Research & Training, Dublin, Ireland
| | - Susan M Farrington
- Colon Cancer Genetics Group, Institute of Genetics and Molecular Medicine, University of Edinburgh and Medical Research Council Human Genetics Unit, Edinburgh, UK
| | - Malcolm G Dunlop
- Colon Cancer Genetics Group, Institute of Genetics and Molecular Medicine, University of Edinburgh and Medical Research Council Human Genetics Unit, Edinburgh, UK
| | - Markus Perola
- Department of Health, The National Institute for Health and Welfare, Helsinki, Finland
| | - Gordan Lauc
- Genos Glycoscience Research Laboratory, Zagreb, Croatia
- University of Zagreb Faculty of Pharmacy and Biochemistry, Zagreb, Croatia
| | - Harry Campbell
- Centre for Global Health Research, Usher Institute for Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK
- Colon Cancer Genetics Group, Institute of Genetics and Molecular Medicine, University of Edinburgh and Medical Research Council Human Genetics Unit, Edinburgh, UK
| | - Pauline M Rudd
- National Institute for Bioprocessing Research & Training, Dublin, Ireland
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O'Hagan S, Wright Muelas M, Day PJ, Lundberg E, Kell DB. GeneGini: Assessment via the Gini Coefficient of Reference "Housekeeping" Genes and Diverse Human Transporter Expression Profiles. Cell Syst 2018; 6:230-244.e1. [PMID: 29428416 PMCID: PMC5840522 DOI: 10.1016/j.cels.2018.01.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/26/2017] [Accepted: 12/30/2017] [Indexed: 01/13/2023]
Abstract
The expression levels of SLC or ABC membrane transporter transcripts typically differ 100- to 10,000-fold between different tissues. The Gini coefficient characterizes such inequalities and here is used to describe the distribution of the expression of each transporter among different human tissues and cell lines. Many transporters exhibit extremely high Gini coefficients even for common substrates, indicating considerable specialization consistent with divergent evolution. The expression profiles of SLC transporters in different cell lines behave similarly, although Gini coefficients for ABC transporters tend to be larger in cell lines than in tissues, implying selection. Transporter genes are significantly more heterogeneously expressed than the members of most non-transporter gene classes. Transcripts with the stablest expression have a low Gini index and often differ significantly from the "housekeeping" genes commonly used for normalization in transcriptomics/qPCR studies. PCBP1 has a low Gini coefficient, is reasonably expressed, and is an excellent novel reference gene. The approach, referred to as GeneGini, provides rapid and simple characterization of expression-profile distributions and improved normalization of genome-wide expression-profiling data.
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Affiliation(s)
- Steve O'Hagan
- School of Chemistry, 131, Princess Street, Manchester M1 7DN, UK; The Manchester Institute of Biotechnology, 131, Princess Street, Manchester M1 7DN, UK
| | - Marina Wright Muelas
- School of Chemistry, 131, Princess Street, Manchester M1 7DN, UK; The Manchester Institute of Biotechnology, 131, Princess Street, Manchester M1 7DN, UK
| | - Philip J Day
- The Manchester Institute of Biotechnology, 131, Princess Street, Manchester M1 7DN, UK; Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Emma Lundberg
- Science for Life Laboratory, Royal Institute of Technology (KTH), SE-17121 Solna, Sweden.
| | - Douglas B Kell
- School of Chemistry, 131, Princess Street, Manchester M1 7DN, UK; The Manchester Institute of Biotechnology, 131, Princess Street, Manchester M1 7DN, UK.
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21
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Gronsbell JL, Cai T. Semi-supervised approaches to efficient evaluation of model prediction performance. J R Stat Soc Series B Stat Methodol 2017. [DOI: 10.1111/rssb.12264] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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Vivo JM, Franco M, Vicari D. Rethinking an ROC partial area index for evaluating the classification performance at a high specificity range. ADV DATA ANAL CLASSI 2017. [DOI: 10.1007/s11634-017-0295-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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23
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Identification of risk factors in epidemiologic study based on ROC curve and network. Sci Rep 2017; 7:46655. [PMID: 28436477 PMCID: PMC5402390 DOI: 10.1038/srep46655] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/28/2017] [Indexed: 11/13/2022] Open
Abstract
This article proposes a new non-parametric approach for identification of risk factors and their correlations in epidemiologic study, in which investigation data may have high variations because of individual differences or correlated risk factors. First, based on classification information of high or low disease incidence, we estimate Receptor Operating Characteristic (ROC) curve of each risk factor. Then, through the difference between ROC curve of each factor and diagonal, we evaluate and screen for the important risk factors. In addition, based on the difference of ROC curves corresponding to any pair of factors, we define a new type of correlation matrix to measure their correlations with disease, and then use this matrix as adjacency matrix to construct a network as a visualization tool for exploring the structure among factors, which can be used to direct further studies. Finally, these methods are applied to analysis on water pollutants and gastrointestinal tumor, and analysis on gene expression data in tumor and normal colon tissue samples.
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24
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Kim S, Huang Y. Combining biomarkers for classification with covariate adjustment. Stat Med 2017; 36:2347-2362. [PMID: 28276080 DOI: 10.1002/sim.7274] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 02/10/2017] [Accepted: 02/10/2017] [Indexed: 11/11/2022]
Abstract
Combining multiple markers can improve classification accuracy compared with using a single marker. In practice, covariates associated with markers or disease outcome can affect the performance of a biomarker or biomarker combination in the population. The covariate-adjusted receiver operating characteristic (ROC) curve has been proposed as a tool to tease out the covariate effect in the evaluation of a single marker; this curve characterizes the classification accuracy solely because of the marker of interest. However, research on the effect of covariates on the performance of marker combinations and on how to adjust for the covariate effect when combining markers is still lacking. In this article, we examine the effect of covariates on classification performance of linear marker combinations and propose to adjust for covariates in combining markers by maximizing the nonparametric estimate of the area under the covariate-adjusted ROC curve. The proposed method provides a way to estimate the best linear biomarker combination that is robust to risk model assumptions underlying alternative regression-model-based methods. The proposed estimator is shown to be consistent and asymptotically normally distributed. We conduct simulations to evaluate the performance of our estimator in cohort and case/control designs and compare several different weighting strategies during estimation with respect to efficiency. Our estimator is also compared with alternative regression-model-based estimators or estimators that maximize the empirical area under the ROC curve, with respect to bias and efficiency. We apply the proposed method to a biomarker study from an human immunodeficiency virus vaccine trial. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Soyoung Kim
- Division of Biostatistics, Medical College of Wisconsin, Milwaukee, WI, U.S.A
| | - Ying Huang
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, 98109, WA, U.S.A
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25
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Muşlu N, Ercan B, Akbayır S, Balcı Ş, Ovla HD, Bozlu M. Neutrophil gelatinase-associated lipocalin as a screening test in prostate cancer. Turk J Urol 2017; 43:30-35. [PMID: 28270948 PMCID: PMC5330265 DOI: 10.5152/tud.2016.08941] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/01/2016] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Prostate specific antigen (PSA) with digital rectal examination is used for diagnosis of prostate cancer (PCa), where definite diagnosis can only be made by prostate biopsy. Recently neutrophil gelatinase-associated lipocalin (NGAL), a lipocalin family member glycoprotein, come into prominence as a cancer biomarker. This study is aimed to test serum NGAL as a diagnostic biomarker for PCa and discriminate PCa from benign prostatic hyperplasia (BPH). MATERIAL AND METHODS In this prospective study, 90 patients who underwent transrectal ultrasound-guided 12-core prostate biopsy between May 2015 and September 2015, were evaluated. Histopathologically diagnosed 45 PCa and 45 BPH patients were enrolled in this study. Serum NGAL and PSA levels of all participants were measured, then these data were evaluated by statistical programs. RESULTS When sensitivity fixed to 80% specificity of NGAL was better than PSA (49%, 31% respectively). Receiver operating characteristic (ROC) curve analysis showed that NGAL alone or its combined use with PSA have better area under curve (AUC) results than PSA alone (0.662, 0.693, and 0.623 respectively). CONCLUSION In conclusion NGAL gave promising results such as increased sensitivity and a better AUC values in order to distinguish PCa from BPH. NGAL showed a potential to be a non-invasive biomarker which may decrease the number of unnecessary biopsies.
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Affiliation(s)
- Necati Muşlu
- Department of Biochemistry, Mersin University School of Medicine, Mersin, Turkey
| | - Bahadır Ercan
- Department of Biochemistry, Dicle University School of Medicine, Diyarbakır, Turkey
| | - Serin Akbayır
- Karaman State Hospital, Biochemistry Laboratory, Karaman, Turkey
| | - Şenay Balcı
- Department of Biochemistry, Mersin University School of Medicine, Mersin, Turkey
| | - H. Didem Ovla
- Department of Biostatistics Mersin University School of Medicine, Mersin, Turkey
| | - Murat Bozlu
- Department of Urology, Mersin University School of Medicine, Mersin, Turkey
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Reaser BC, Wright BW, Synovec RE. Using Receiver Operating Characteristic Curves To Optimize Discovery-Based Software with Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry. Anal Chem 2017; 89:3606-3612. [DOI: 10.1021/acs.analchem.6b04991] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Brooke C. Reaser
- Department
of Chemistry, University of Washington, Box 351700, Seattle, Washington 98198, United States
| | - Bob W. Wright
- Pacific Northwest National Laboratory, Battelle
Boulevard, P.O. Box 999, Richland, Washington 99352, United States
| | - Robert E. Synovec
- Department
of Chemistry, University of Washington, Box 351700, Seattle, Washington 98198, United States
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Dhingra R, Vasan RS. Biomarkers in cardiovascular disease: Statistical assessment and section on key novel heart failure biomarkers. Trends Cardiovasc Med 2017; 27:123-133. [PMID: 27576060 PMCID: PMC5253084 DOI: 10.1016/j.tcm.2016.07.005] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 07/23/2016] [Accepted: 07/23/2016] [Indexed: 12/11/2022]
Abstract
Cardiovascular disease (CVD) is a leading cause of death worldwide and continues to increase in prevalence compared to previous decades, in part because of the aging of the world population. Atherosclerotic CVD starts at a very young age and progresses over time allowing sufficient time for screening and early detection of the condition. Advances in biomarker research and developments related to CVD over the past 30 years have led to more sensitive screening methods, a greater emphasis on its early detection and diagnosis, and improved treatments resulting in more favorable clinical outcomes in the community. However, the use of biomarkers for different purposes in CVD remains an important area of research that has been explored by scientists over the years and many new developments are still underway. Therefore, a detailed description of all CVD biomarkers that are currently been used or investigated for future use in the field of cardiovascular medicine is out of scope for any review article. In the present review, we do not intend to replicate the information from previous exhaustive review on biomarkers, but highlight key statistical and clinical issues with an emphasis on methods to evaluate the incremental yield of biomarkers, including their clinical utility, a prerequisite before any putative novel biomarker is utilized in clinical practice. In addition, we will summarize information regarding recent novel heart failure biomarkers in current practice, which are undergoing scrutiny before they can be available for clinical use, and their impact on clinical outcomes.
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Affiliation(s)
- Ravi Dhingra
- Division of Cardiovascular Medicine, University of Wisconsin-Madison, 600 Highland Avenue, E5/582C, MC 5710, Madison, WI 53792.
| | - Ramachandran S Vasan
- Division of Cardiovascular Medicine, University of Wisconsin-Madison, 600 Highland Avenue, E5/582C, MC 5710, Madison, WI 53792
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28
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Hackner K, Pleil J. Canine olfaction as an alternative to analytical instruments for disease diagnosis: understanding 'dog personality' to achieve reproducible results. J Breath Res 2017; 11:012001. [PMID: 28068294 DOI: 10.1088/1752-7163/aa5524] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Recent literature has touted the use of canine olfaction as a diagnostic tool for identifying pre-clinical disease status, especially cancer and infection from biological media samples. Studies have shown a wide range of outcomes, ranging from almost perfect discrimination, all the way to essentially random results. This disparity is not likely to be a detection issue; dogs have been shown to have extremely sensitive noses as proven by their use for tracking, bomb detection and search and rescue. However, in contrast to analytical instruments, dogs are subject to boredom, fatigue, hunger and external distractions. These challenges are of particular importance in a clinical environment where task repetition is prized, but not as entertaining for a dog as chasing odours outdoors. The question addressed here is how to exploit the intrinsic sensitivity and simplicity of having a dog simply sniff out disease, in the face of variability in behavior and response.
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Affiliation(s)
- Klaus Hackner
- Department of Pneumonology, Krems University Hospital, Krems, Austria. Karl Landsteiner University of Health Sciences, Krems, Austria
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29
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Assel M, Sjoberg DD, Vickers AJ. The Brier score does not evaluate the clinical utility of diagnostic tests or prediction models. Diagn Progn Res 2017; 1:19. [PMID: 31093548 PMCID: PMC6460786 DOI: 10.1186/s41512-017-0020-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 11/20/2017] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND A variety of statistics have been proposed as tools to help investigators assess the value of diagnostic tests or prediction models. The Brier score has been recommended on the grounds that it is a proper scoring rule that is affected by both discrimination and calibration. However, the Brier score is prevalence dependent in such a way that the rank ordering of tests or models may inappropriately vary by prevalence. METHODS We explored four common clinical scenarios: comparison of a highly accurate binary test with a continuous prediction model of moderate predictiveness; comparison of two binary tests where the importance of sensitivity versus specificity is inversely associated with prevalence; comparison of models and tests to default strategies of assuming that all or no patients are positive; and comparison of two models with miscalibration in opposite directions. RESULTS In each case, we found that the Brier score gave an inappropriate rank ordering of the tests and models. Conversely, net benefit, a decision-analytic measure, gave results that always favored the preferable test or model. CONCLUSIONS Brier score does not evaluate clinical value of diagnostic tests or prediction models. We advocate, as an alternative, the use of decision-analytic measures such as net benefit. TRIAL REGISTRATION Not applicable.
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Affiliation(s)
- Melissa Assel
- 0000 0001 2171 9952grid.51462.34Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Daniel D. Sjoberg
- 0000 0001 2171 9952grid.51462.34Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Andrew J. Vickers
- 0000 0001 2171 9952grid.51462.34Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, USA
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30
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Jeske DR, Smith S. Maximizing the usefulness of statistical classifiers for two populations with illustrative applications. Stat Methods Med Res 2016; 27:2344-2358. [PMID: 27920365 DOI: 10.1177/0962280216680244] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The usefulness of two-class statistical classifiers is limited when one or both of the conditional misclassification rates is unacceptably high. Incorporating a neutral zone region into the classifier provides a mechanism to refer ambiguous cases to follow-up where additional information might be obtained to clarify the classification decision. Through the use of the neutral zone region, the conditional misclassification rates can be controlled and the classifier becomes useful. Three real-life examples, including applications to prostate cancer and kidney dysfunction following heart surgery, are used to illustrate how neutral zone regions can extract utility from disappointing classifiers that might otherwise be abandoned.
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Affiliation(s)
- Daniel R Jeske
- 1 Department of Statistics, University of California - Riverside, USA
| | - Steven Smith
- 2 Division of Urology and Urological Oncology, City of Hope National Medical Center, USA
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Martínez-Camblor P. Fully non-parametric receiver operating characteristic curve estimation for random-effects meta-analysis. Stat Methods Med Res 2016; 26:5-20. [DOI: 10.1177/0962280214537047] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Meta-analyses, broadly defined as the quantitative review and synthesis of the results of related but independent comparable studies, allow to know the state of the art of one considered topic. Since the amount of available bibliography has enhanced in almost all fields and, specifically, in biomedical research, its popularity has drastically increased during the last decades. In particular, different methodologies have been developed in order to perform meta-analytic studies of diagnostic tests for both fixed- and random-effects models. From a parametric point of view, these techniques often compute a bivariate estimation for the sensitivity and the specificity by using only one threshold per included study. Frequently, an overall receiver operating characteristic curve based on a bivariate normal distribution is also provided. In this work, the author deals with the problem of estimating an overall receiver operating characteristic curve from a fully non-parametric approach when the data come from a meta-analysis study i.e. only certain information about the diagnostic capacity is available. Both fixed- and random-effects models are considered. In addition, the proposed methodology lets to use the information of all cut-off points available (not only one of them) in the selected original studies. The performance of the method is explored through Monte Carlo simulations. The observed results suggest that the proposed estimator is better than the reference one when the reported information is related to a threshold based on the Youden index and when information for two or more points are provided. Real data illustrations are included.
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Affiliation(s)
- Pablo Martínez-Camblor
- Oficina de Investigación Biosanitaria de Asturies (OIB-FICYT) and Universidad de Oviedo, Oviedo, Spain
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Battelino N, Ključevšek D, Tomažič M, Levart TK. Vesicoureteral refux detection in children: a comparison of the midline-to-orifice distance measurement by ultrasound and voiding urosonography. Pediatr Nephrol 2016; 31:957-64. [PMID: 26781473 DOI: 10.1007/s00467-015-3301-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 12/07/2015] [Accepted: 12/09/2015] [Indexed: 11/27/2022]
Abstract
BACKGROUND Due to the questionable clinical role of vesicoureteral reflux (VUR) and the search for noninvasive, radiation-free procedures sufficiently reliable to detect VUR, we compared the correlation between the midline-to-orifice distance (MOD) measured by ultrasonography (US) and echo-enhanced voiding urosonography (VUS) for detecting VUR in children. The aim of the study was to determine whether measuring MOD by US could be a reliable predictor of VUR in children. METHODS A total of 116 children, aged 0.25-84 months, with 232 potentially refluxing units were investigated simultaneously by measuring the MOD and performing VUS. Indications for cystography were urinary tract infection and follow-up of a previously detected VUR. VUS was performed after the MOD measurement. The results were analyzed with VUS as the reference method. RESULTS The MOD was significantly larger in VUR grade III (10.7 mm; p = 0.003) and VUR grade II (9.9 mm; p = 0.001) refluxing units than in non-refluxing units (7.8 mm), even when controlling for the estimated volume/expected maximal capacity (Vest/Vmax) ratio. A MOD cutoff value of 7.4 mm was chosen as a predictor of either the presence or absence of VUR; the sensitivity and specificity of this cutoff measurement for VUR detection were found to be 89 and 24%, respectively. CONCLUSIONS Despite the statistically significant difference between the MOD of refluxing versus non-refluxing units identified in our study, the MOD measurement needs further evaluation to determine its potential value as a diagnostic tool for the detection of VUR.
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Affiliation(s)
- Nina Battelino
- Department of Pediatric Nephrology, University Medical Centre Ljubljana, Ljubljana, Slovenia.
| | - Damjana Ključevšek
- Department of Pediatric Radiology, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Mojca Tomažič
- Department of Pediatric Radiology, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Tanja Kersnik Levart
- Department of Pediatric Nephrology, University Medical Centre Ljubljana, Ljubljana, Slovenia
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Gururajan A, Clarke G, Dinan TG, Cryan JF. Molecular biomarkers of depression. Neurosci Biobehav Rev 2016; 64:101-33. [DOI: 10.1016/j.neubiorev.2016.02.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/11/2016] [Accepted: 02/12/2016] [Indexed: 12/22/2022]
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Abstract
The nutritional status of an individual or population needs to be assessed through valid and reliable biomarkers. Cutoffs generally have an underlying relation to health status and are one of the important quantitative criteria against which biomarker outputs are compared. For this reason, cutoffs are integral for surveys, surveillance, screening, interventions, monitoring, and evaluation. Despite their importance, nutritional biomarker cutoffs have not been adequately addressed in the literature. Furthermore, the field has not reached a consensus on which cutoff to use for each biomarker, and different cutoffs are often used for the same biomarkers in published studies. This review provides a comprehensive overview of cutoffs related to nutritional biomarkers and highlights some of the high-priority research gaps and challenges of using micronutrient case studies.
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Affiliation(s)
- Ramkripa Raghavan
- Center on the Early Life Origins of Disease, Department of Population, Family and Reproductive Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD;
| | - Fayrouz Sakr Ashour
- Department of Nutrition and Food Science, University of Maryland, College Park, MD; and
| | - Regan Bailey
- Office of Dietary Supplements, NIH, Bethesda, MD
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Gravante G, Parker R, Elshaer M, Mogekwu AC, Humayun N, Thomas K, Thomson R, Hudson S, Sorge R, Gardiner K, Al-Hamali S, Rashed M, Kelkar A, El-Rabaa S. Lymph node retrieval for colorectal cancer: Estimation of the minimum resection length to achieve at least 12 lymph nodes for the pathological analysis. Int J Surg 2015; 25:153-7. [PMID: 26713777 DOI: 10.1016/j.ijsu.2015.12.062] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/15/2015] [Indexed: 01/24/2023]
Abstract
INTRODUCTION Adequate lymph node retrieval is important in colorectal cancer staging for the selection of patients that necessitate adjuvant treatments. The minimum number of 12 lymph nodes is one of the premises and is dependent, among the other factors, from the length of bowel resected. We have reviewed our specimens to identify the high-risk operations for inadequate nodal sampling and estimate the minimum length of bowel needed to resect to achieve this purpose. MATERIALS AND METHODS A retrospective review of colorectal specimens over 10 years of activity looking at data including location of the tumor, type of operation performed, length of bowel resected and number of lymph nodes retrieved. RESULTS Abdominoperineal and Hartmann's resections produced significant lower adequate retrievals compared to other colorectal operations, corresponding to 45.4% and 59.1% of cases respectively. The measured average length of bowel was 30 cm and 25 cm respectively, increasing the length to 36 cm and 42 cm would increase the adequacy rate to 90%. CONCLUSIONS Abdominoperineal and Hartmann's resections are, in our series, high-risk operations that frequently do not produce the minimum number of lymph nodes necessary. These operations may require additional maneuvers such as mobilization of the splenic flexure to achieve the minimum length of bowel to resect.
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Affiliation(s)
- Gianpiero Gravante
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Rupert Parker
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Mohamed Elshaer
- Department of Surgery, West Hertfordshire Hospitals, Watford, United Kingdom.
| | | | - Nada Humayun
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Katie Thomas
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Rachael Thomson
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Sarah Hudson
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Roberto Sorge
- Department of Human Physiology, Laboratory of Biometry, University of Tor Vergata, Rome, Italy
| | - Katy Gardiner
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Salem Al-Hamali
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Mohamed Rashed
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Ashish Kelkar
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
| | - Saleem El-Rabaa
- Department of Surgery, Kettering General Hospital, Kettering, United Kingdom
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Ozkumur AY, Goods BA, Love JC. Development of a High-Throughput Functional Screen Using Nanowell-Assisted Cell Patterning. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:4643-50. [PMID: 26121321 PMCID: PMC4754792 DOI: 10.1002/smll.201500674] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/30/2015] [Indexed: 05/04/2023]
Abstract
Living-cell-based screens can facilitate lead discovery of functional therapeutics of interest. A versatile and scalable method is reported that uses dense arrays of nanowells for imparting defined patterns on monolayers of cells. It is shown that this approach can coordinate a multi-component biological assay by designing and implementing a high-throughput, functional nanoliter-scale neutralization assay to identify neutralizing antibodies against HIV.
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Affiliation(s)
- Ayca Yalcin Ozkumur
- Electrical and Electronics Engineering Department, Bahcesehir University, Istanbul, Turkey
| | - Brittany A. Goods
- Department of Biological Engineering, Koch Institute for Integrative Cancer Research at MIT, Cambridge, Massachusetts 02139, USA
| | - J. Christopher Love
- Department of Chemical Engineering, Koch Institute for Integrative Cancer Research at MIT Cambridge, Massachusetts 02139, USA
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- The Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139, United States
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Ebersole JL, Nagarajan R, Akers D, Miller CS. Targeted salivary biomarkers for discrimination of periodontal health and disease(s). Front Cell Infect Microbiol 2015; 5:62. [PMID: 26347856 PMCID: PMC4541326 DOI: 10.3389/fcimb.2015.00062] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/03/2015] [Indexed: 11/13/2022] Open
Abstract
UNLABELLED Generally, clinical parameters are used in dental practice for periodontal disease, yet several drawbacks exist with the clinical standards for addressing the needs of the public at large in determining the current status/progression of the disease, and requiring a significant amount of damage before these parameters can document disease. Therefore, a quick, easy and reliable method of assessing and monitoring periodontal disease should provide important diagnostic information that improves and speeds treatment decisions and moves the field closer to individualized point-of-care diagnostics. OBJECTIVE This report provides results for a saliva-based diagnostic approach for periodontal health and disease based upon the abundance of salivary analytes coincident with disease, and the significant progress already made in the identification of discriminatory salivary biomarkers of periodontitis. METHODS We evaluated biomarkers representing various phases of periodontitis initiation and progression (IL-1ß, IL-6, MMP-8, MIP-1α) in whole saliva from 209 subjects categorized with periodontal health, gingivitis, and periodontitis. RESULTS Evaluation of the salivary analytes demonstrated utility for individual biomarkers to differentiate periodontitis from health. Inclusion of gingivitis patients into the analyses provided a more robust basis to estimate the value of each of these analytes. Various clinical and statistical approaches showed that pairs or panels of the analytes were able to increase the sensitivity and specificity for the identification of disease. CONCLUSIONS Salivary concentrations of IL-1ß, IL-6, MMP-8, MIP-1α alone and in combination are able to distinguish health from gingivitis and periodontitis. The data clearly demonstrated a heterogeneity in response profiles of these analytes that supports the need for refinement of the standard clinical classifications if we are to move toward precision/personalized dentistry for the twenty-first century.
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Affiliation(s)
- Jeffrey L Ebersole
- Center for Oral Health Research, College of Dentistry, University of Kentucky Lexington, KY, USA
| | - Radhakrishnan Nagarajan
- Division of Biomedical Informatics, College of Public Health, University of Kentucky Lexington, KY, USA
| | - David Akers
- Department of Statistics, College of Arts and Sciences, University of Kentucky Lexington, KY, USA
| | - Craig S Miller
- Center for Oral Health Research, College of Dentistry, University of Kentucky Lexington, KY, USA ; Division of Oral Diagnosis, Oral Medicine and Oral Radiology, College of Dentistry, University of Kentucky Lexington, KY, USA
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Baker SG, Xu JL, Hu P, Huang P. Vardeman, S. B. and Morris, M. D. (2013), "Majority Voting by Independent Classifiers can Increase Error Rates," The American Statistician, 67, 94-96: Comment by Baker, Xu, Hu, and Huang and Reply. AM STAT 2015; 68:125-126. [PMID: 26113746 DOI: 10.1080/00031305.2014.882867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
| | | | | | - Peng Huang
- Johns Hopkins Medical Institution, In the Public Domain
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Karagiannis P, Villanova F, Josephs DH, Correa I, Van Hemelrijck M, Hobbs C, Saul L, Egbuniwe IU, Tosi I, Ilieva KM, Kent E, Calonje E, Harries M, Fentiman I, Taylor-Papadimitriou J, Burchell J, Spicer JF, Lacy KE, Nestle FO, Karagiannis SN. Elevated IgG4 in patient circulation is associated with the risk of disease progression in melanoma. Oncoimmunology 2015; 4:e1032492. [PMID: 26451312 PMCID: PMC4590000 DOI: 10.1080/2162402x.2015.1032492] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 03/14/2015] [Accepted: 03/17/2015] [Indexed: 01/27/2023] Open
Abstract
Emerging evidence suggests pathological and immunoregulatory functions for IgG4 antibodies and IgG4+ B cells in inflammatory diseases and malignancies. We previously reported that IgG4 antibodies restrict activation of immune effector cell functions and impair humoral responses in melanoma. Here, we investigate IgG4 as a predictor of risk for disease progression in a study of human sera (n = 271: 167 melanoma patients; 104 healthy volunteers) and peripheral blood B cells (n = 71: 47 melanoma patients; 24 healthy volunteers). IgG4 (IgG4/IgGtotal) serum levels were elevated in melanoma. High relative IgG4 levels negatively correlated with progression-free survival (PFS) and overall survival. In early stage (I-II) disease, serum IgG4 was independently negatively prognostic for progression-free survival, as was elevation of IgG4+ circulating B cells (CD45+CD22+CD19+CD3-CD14-). In human tissues (n = 256; 108 cutaneous melanomas; 56 involved lymph nodes; 60 distant metastases; 32 normal skin samples) IgG4+ cell infiltrates were found in 42.6% of melanomas, 21.4% of involved lymph nodes and 30% of metastases, suggesting inflammatory conditions that favor IgG4 at the peripheral and local levels. Consistent with emerging evidence for an immunosuppressive role for IgG4, these findings indicate association of elevated IgG4 with disease progression and less favorable clinical outcomes. Characterizing immunoglobulin and other humoral immune profiles in melanoma might identify valuable prognostic tools for patient stratification and in the future lead to more effective treatments less prone to tumor-induced blockade mechanisms.
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Affiliation(s)
- Panagiotis Karagiannis
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK ; University Hospital of Hamburg Eppendorf; Department of Oncology; Hematology and Stem Cell Transplantation ; Hamburg, Germany
| | - Federica Villanova
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK
| | - Debra H Josephs
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK ; Department of Research Oncology; Division of Cancer Studies; Faculty of Life Sciences and Medicine; King's College London; Guy's Hospital ; London, UK
| | - Isabel Correa
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK
| | - Mieke Van Hemelrijck
- King's College London; Faculty of Life Sciences and Medicine; Division of Cancer Studies; Cancer Epidemiology Group; Guy's Hospital; London, UK
| | - Carl Hobbs
- Wolfson Center for Age-Related Diseases; King's College London ; London, UK
| | - Louise Saul
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK ; Department of Research Oncology; Division of Cancer Studies; Faculty of Life Sciences and Medicine; King's College London; Guy's Hospital ; London, UK
| | - Isioma U Egbuniwe
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK
| | - Isabella Tosi
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK
| | - Kristina M Ilieva
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK ; Breakthrough Breast Cancer Research Unit; Department of Research Oncology; Guy's Hospital; King's College London School of Medicine ; London, United Kingdom
| | - Emma Kent
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK
| | - Eduardo Calonje
- Skin Tumor Unit; St. John's Institute of Dermatology; Guy's Hospital, King's College London and Guy's and St Thomas' NHS Trust ; London, UK
| | - Mark Harries
- Clinical Oncology; Guy's and St. Thomas's NHS Foundation Trust , London, UK
| | - Ian Fentiman
- Department of Research Oncology; Division of Cancer Studies; Faculty of Life Sciences and Medicine; King's College London; Guy's Hospital ; London, UK
| | - Joyce Taylor-Papadimitriou
- Department of Research Oncology; Division of Cancer Studies; Faculty of Life Sciences and Medicine; King's College London; Guy's Hospital ; London, UK
| | - Joy Burchell
- Department of Research Oncology; Division of Cancer Studies; Faculty of Life Sciences and Medicine; King's College London; Guy's Hospital ; London, UK
| | - James F Spicer
- Department of Research Oncology; Division of Cancer Studies; Faculty of Life Sciences and Medicine; King's College London; Guy's Hospital ; London, UK
| | - Katie E Lacy
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK ; Skin Tumor Unit; St. John's Institute of Dermatology; Guy's Hospital, King's College London and Guy's and St Thomas' NHS Trust ; London, UK
| | - Frank O Nestle
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK
| | - Sophia N Karagiannis
- St. John's Institute of Dermatology; Division of Genetics and Molecular Medicine; Faculty of Life Sciences and Medicine; King's College London & NIHR Biomedical Research Centre at Guy's and St. Thomas' Hospitals and King's College London; Guy's Hospital; King's College London ; London, UK
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Predictive Levels of CD24 in Peripheral Blood Leukocytes for the Early Detection of Colorectal Adenomas and Adenocarcinomas. DISEASE MARKERS 2015; 2015:916098. [PMID: 26078485 PMCID: PMC4442284 DOI: 10.1155/2015/916098] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 03/12/2015] [Accepted: 03/29/2015] [Indexed: 01/05/2023]
Abstract
CD24 is expressed in 90% of colorectal adenomas and adenocarcinomas. Colorectal cancer (CRC) can be mostly prevented but average risk population screening by stool testing or colonoscopy faces many hurdles. Blood testing is clinically needed. We aimed to evaluate the utility of CD24 expression in peripheral blood leukocytes (PBLs).
Two independent case studies were conducted in eligible individuals undergoing colonoscopy. Protein extracted from PBLs was subjected to immunoblotting using anti-CD24 monoclonal antibodies. CD24 sensitivity and specificity were determined using receiver operating characteristic (ROC) analysis. Initially, 150 subjects were examined: 63 had CRC, 19 had adenomas, and 68 had normal colonoscopies. The sensitivity and specificity of CD24 for distinguishing CRC from normal subjects were 70.5% (95% CI, 54.8–83.2%) and 83.8% (95% CI, 74.6–92.7%) and for adenomas 84.2% (95% CI, 60.4–96.4%) and 73.5% (95% CI, 61.4–83.5%), respectively. In the second trial (n = 149), a similar specificity but higher sensitivity was achieved: 80.0% (95% CI, 63.1–91.6%) for CRC and 89.2% (95% CI, 74.6–97%) for adenomas. A simple noninvasive blood test evaluating CD24 levels has high sensitivity and specificity for detecting colorectal adenomas and cancer in patients undergoing colonoscopy at an urban medical center. Larger multicenter studies are warranted to establish the potential of this promising test.
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Halligan S, Altman DG, Mallett S. Disadvantages of using the area under the receiver operating characteristic curve to assess imaging tests: a discussion and proposal for an alternative approach. Eur Radiol 2015; 25:932-9. [PMID: 25599932 PMCID: PMC4356897 DOI: 10.1007/s00330-014-3487-0] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/16/2014] [Accepted: 11/03/2014] [Indexed: 11/28/2022]
Abstract
OBJECTIVES The objectives are to describe the disadvantages of the area under the receiver operating characteristic curve (ROC AUC) to measure diagnostic test performance and to propose an alternative based on net benefit. METHODS We use a narrative review supplemented by data from a study of computer-assisted detection for CT colonography. RESULTS We identified problems with ROC AUC. Confidence scoring by readers was highly non-normal, and score distribution was bimodal. Consequently, ROC curves were highly extrapolated with AUC mostly dependent on areas without patient data. AUC depended on the method used for curve fitting. ROC AUC does not account for prevalence or different misclassification costs arising from false-negative and false-positive diagnoses. Change in ROC AUC has little direct clinical meaning for clinicians. An alternative analysis based on net benefit is proposed, based on the change in sensitivity and specificity at clinically relevant thresholds. Net benefit incorporates estimates of prevalence and misclassification costs, and it is clinically interpretable since it reflects changes in correct and incorrect diagnoses when a new diagnostic test is introduced. CONCLUSIONS ROC AUC is most useful in the early stages of test assessment whereas methods based on net benefit are more useful to assess radiological tests where the clinical context is known. Net benefit is more useful for assessing clinical impact. KEY POINTS • The area under the receiver operating characteristic curve (ROC AUC) measures diagnostic accuracy. • Confidence scores used to build ROC curves may be difficult to assign. • False-positive and false-negative diagnoses have different misclassification costs. • Excessive ROC curve extrapolation is undesirable. • Net benefit methods may provide more meaningful and clinically interpretable results than ROC AUC.
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Affiliation(s)
- Steve Halligan
- Centre for Medical Imaging, University College Hospital, University College London, Podium Level 2, 235 Euston Road, London, NW1 2BU, UK,
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Paczesny S, Duncan C, Jacobsohn D, Krance R, Leung K, Carpenter P, Bollard C, Renbarger J, Cooke K. Opportunities and challenges of proteomics in pediatric patients: circulating biomarkers after hematopoietic stem cell transplantation as a successful example. Proteomics Clin Appl 2014; 8:837-50. [PMID: 25196024 DOI: 10.1002/prca.201400033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 06/30/2014] [Accepted: 09/03/2014] [Indexed: 11/06/2022]
Abstract
Biomarkers have the potential to improve diagnosis and prognosis, facilitate-targeted treatment, and reduce health care costs. Thus, there is great hope that biomarkers will be integrated in all clinical decisions in the near future. A decade ago, the biomarker field was launched with great enthusiasm because MS revealed that blood contains a rich library of candidate biomarkers. However, biomarker research has not yet delivered on its promise due to several limitations: (i) improper sample handling and tracking as well as limited sample availability in the pediatric population, (ii) omission of appropriate controls in original study designs, (iii) lability and low abundance of interesting biomarkers in blood, and (iv) the inability to mechanistically tie biomarker presence to disease biology. These limitations as well as successful strategies to overcome them are discussed in this review. Several advances in biomarker discovery and validation have been made in hematopoietic stem cell transplantation, the current most effective tumor immunotherapy, and these could serve as examples for other conditions. This review provides fresh optimism that biomarkers clinically relevant in pediatrics are closer to being realized based on: (i) a uniform protocol for low-volume blood collection and preservation, (ii) inclusion of well-controlled independent cohorts, (iii) novel technologies and instrumentation with low analytical sensitivity, and (iv) integrated animal models for exploring potential biomarkers and targeted therapies.
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Affiliation(s)
- Sophie Paczesny
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
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Frantzi M, Bhat A, Latosinska A. Clinical proteomic biomarkers: relevant issues on study design & technical considerations in biomarker development. Clin Transl Med 2014; 3:7. [PMID: 24679154 PMCID: PMC3994249 DOI: 10.1186/2001-1326-3-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 03/06/2014] [Indexed: 12/11/2022] Open
Abstract
Biomarker research is continuously expanding in the field of clinical proteomics. A combination of different proteomic-based methodologies can be applied depending on the specific clinical context of use. Moreover, current advancements in proteomic analytical platforms are leading to an expansion of biomarker candidates that can be identified. Specifically, mass spectrometric techniques could provide highly valuable tools for biomarker research. Ideally, these advances could provide with biomarkers that are clinically applicable for disease diagnosis and/ or prognosis. Unfortunately, in general the biomarker candidates fail to be implemented in clinical decision making. To improve on this current situation, a well-defined study design has to be established driven by a clear clinical need, while several checkpoints between the different phases of discovery, verification and validation have to be passed in order to increase the probability of establishing valid biomarkers. In this review, we summarize the technical proteomic platforms that are available along the different stages in the biomarker discovery pipeline, exemplified by clinical applications in the field of bladder cancer biomarker research.
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Affiliation(s)
- Maria Frantzi
- Mosaiques Diagnostics GmbH, Mellendorfer Strasse 7-9, D-30625 Hannover, Germany
- Biotechnology Division, Biomedical Research Foundation Academy of Athens, Soranou Ephessiou 4, 115 27 Athens, Greece
| | - Akshay Bhat
- Mosaiques Diagnostics GmbH, Mellendorfer Strasse 7-9, D-30625 Hannover, Germany
- Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Agnieszka Latosinska
- Biotechnology Division, Biomedical Research Foundation Academy of Athens, Soranou Ephessiou 4, 115 27 Athens, Greece
- Charité-Universitätsmedizin Berlin, Berlin, Germany
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Vecchio D, Daga A, Carra E, Marubbi D, Baio G, Neumaier CE, Vagge S, Corvò R, Pia Brisigotti M, Louis Ravetti J, Zunino A, Poggi A, Mascelli S, Raso A, Frosina G. Predictability, efficacy and safety of radiosensitization of glioblastoma-initiating cells by the ATM inhibitor KU-60019. Int J Cancer 2014; 135:479-91. [PMID: 24443327 DOI: 10.1002/ijc.28680] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 11/21/2013] [Accepted: 11/25/2013] [Indexed: 12/12/2022]
Abstract
We have previously shown that pharmacological inhibition of ataxia telangiectasia mutated (ATM) protein sensitizes glioblastoma-initiating cells (GICs) to ionizing radiation (IR). Herein, we report the experimental conditions to overcome GIC radioresistance in vitro using the specific ATM inhibitor KU-60019, two major determinants of the tumor response to this drug and the absence of toxicity of this treatment in vitro and in vivo. Repeated treatments with KU-60019 followed by IR substantially delayed GIC proliferation in vitro and even eradicated radioresistant cells, whereas GIC treated with vehicle plus radiation recovered early and expanded. The tumor response to the drug occurred under a cutoff level of expression of TP53 and over a cutoff level of expression of phosphatidylinositol 3-kinase (PI3K). No increased clastogenicity or point mutagenicity was induced by KU-60019 plus radiation when compared to vehicle plus radiation. No significant histological changes to the brain or other organs were observed after prolonged infusion into the brain of KU-60019 at millimolar concentrations. Taken together, these findings suggest that GIC-driven tumors with low expression of TP53 and high expression of PI3K might be effectively and safely radiosensitized by KU-60019.
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Affiliation(s)
- Donatella Vecchio
- Mutagenesis Unit, IRCCS Azienda Ospedaliera Universitaria San Martino, IST Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy
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Huang D, Li R, Wang H. Feature Screening for Ultrahigh Dimensional Categorical Data with Applications. JOURNAL OF BUSINESS & ECONOMIC STATISTICS : A PUBLICATION OF THE AMERICAN STATISTICAL ASSOCIATION 2014; 32:237-244. [PMID: 25328278 PMCID: PMC4197855 DOI: 10.1080/07350015.2013.863158] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Ultrahigh dimensional data with both categorical responses and categorical covariates are frequently encountered in the analysis of big data, for which feature screening has become an indispensable statistical tool. We propose a Pearson chi-square based feature screening procedure for categorical response with ultrahigh dimensional categorical covariates. The proposed procedure can be directly applied for detection of important interaction effects. We further show that the proposed procedure possesses screening consistency property in the terminology of Fan and Lv (2008). We investigate the finite sample performance of the proposed procedure by Monte Carlo simulation studies, and illustrate the proposed method by two empirical datasets.
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Affiliation(s)
| | - Runze Li
- Peking University & Pennsylvania State University
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Limitations of early serum creatinine variations for the assessment of kidney injury in neonates and infants with cardiac surgery. PLoS One 2013; 8:e79308. [PMID: 24244476 PMCID: PMC3823616 DOI: 10.1371/journal.pone.0079308] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 09/23/2013] [Indexed: 01/11/2023] Open
Abstract
Background Changes in kidney function, as assessed by early and even small variations in serum creatinine (ΔsCr), affect survival in adults following cardiac surgery but such associations have not been reported in infants. This raises the question of the adequate assessment of kidney function by early ΔsCr in infants undergoing cardiac surgery. Methodology The ability of ΔsCr within 2 days of surgery to assess the severity of kidney injury, accounted for by the risk of 30-day mortality, was explored retrospectively in 1019 consecutive neonates and infants. Patients aged ≤ 10 days were analyzed separately because of the physiological improvement in glomerular filtration early after birth. The Kml algorithm, an implementation of k-means for longitudinal data, was used to describe creatinine kinetics, and the receiver operating characteristic and the reclassification methodology to assess discrimination and the predictive ability of the risk of death. Results Three clusters of ΔsCr were identified: in 50% of all patients creatinine decreased, in 41.4% it increased slightly, and in 8.6% it rose abruptly. Mortality rates were not significantly different between the first and second clusters, 1.6% [0.0–4.1] vs 5.9% [1.9–10.9], respectively, in patients aged ≤ 10 days, and 1.6% [0.5–3.0] vs 3.8% [1.9–6.0] in older ones. Mortality rates were significantly higher when creatinine rose abruptly, 30.3% [15.1–46.2] in patients aged ≤ 10 days, and 15.1% [5.9–25.5] in older ones. However, only 41.3% of all patients who died had an abrupt increase in creatinine. ΔsCr improved prediction in survivors, but not in patients who died, and did not improve discrimination over a clinical mortality model. Conclusions The present results suggest that a postoperative decrease in creatinine represents the normal course in neonates and infants with cardiac surgery, and that early creatinine variations lack sensitivity for the assessment of the severity of kidney injury.
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Perez-Riverol Y, Sánchez A, Noda J, Borges D, Carvalho PC, Wang R, Vizcaíno JA, Betancourt L, Ramos Y, Duarte G, Nogueira FCS, González LJ, Padrón G, Tabb DL, Hermjakob H, Domont GB, Besada V. HI-bone: a scoring system for identifying phenylisothiocyanate-derivatized peptides based on precursor mass and high intensity fragment ions. Anal Chem 2013; 85:3515-20. [PMID: 23448308 DOI: 10.1021/ac303239g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide sequence matching algorithms used for peptide identification by tandem mass spectrometry (MS/MS) enumerate theoretical peptides from the database, predict their fragment ions, and match them to the experimental MS/MS spectra. Here, we present an approach for scoring MS/MS identifications based on the high mass accuracy matching of precursor ions, the identification of a high intensity b1 fragment ion, and partial sequence tags from phenylthiocarbamoyl-derivatized peptides. This derivatization process boosts the b1 fragment ion signal, which turns it into a powerful feature for peptide identification. We demonstrate the effectiveness of our scoring system by implementing it on a computational tool called "HI-bone" and by identifying mass spectra of an Escherichia coli sample acquired on an Orbitrap Velos instrument using Higher-energy C-trap dissociation. Following this strategy, we identified 1614 peptide spectrum matches with a peptide false discovery rate (FDR) below 1%. These results were significantly higher than those from Mascot and SEQUEST using a similar FDR.
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Affiliation(s)
- Yasset Perez-Riverol
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Cubanacán, Playa, Ciudad de la Habana, Cuba
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