Matted Lymph Nodes on MRI in Nasopharyngeal Carcinoma: Prognostic Factor and Potential Indication for Induction Chemotherapy Benefits

BACKGROUND

Lymph node characteristics markedly affect nasopharyngeal carcinoma (NPC) prognosis. Matted node (MN), an important characteristic for lymph node, lacks explored MRI-based prognostic implications.

PURPOSE

Investigate MRI-determined MNs' prognostic value in NPC, including 5-year overall survival (OS), distant metastasis-free survival (DMFS), local recurrence-free survival (LRFS), progression-free survival (PFS), and its role in induction chemotherapy (IC).

STUDY TYPE

Retrospective cohort survival study.

POPULATION

Seven hundred ninety-two patients with non-metastatic NPC (female: 27.3%, >45-year old: 50.1%) confirmed by biopsy.

FIELD STRENGTH/SEQUENCE

5-T/3.0-T, T1-, T2- and post-contrast T1-weighted fast spin echo sequences acquired.

ASSESSMENT

MNs were defined as ≥3 nodes abutting with intervening fat plane replaced by extracapsular nodal spread (ENS). Patients were observed every 3 months for 2 years and every 6 months for 5 years using MRI. Follow-up extended from treatment initiation to death or final follow-up. MNs were evaluated by three radiologists with inter-reader reliability calculated. A 1:1 matched-pair method compared survival differences between MN-positive patients with or without IC. Primary endpoints (OS, DMFS, LRFS, PFS) were calculated from therapy initiation to respective event.

STATISTICAL TESTS

Kappa values assessed inter-reader reliability. Correlation between MN, ENS, and LNN was studied through Spearman's correlation coefficient. Clinical characteristics were calculated via Fisher's exact, Chi-squared, and Student's t-test. Kaplan-Meier curves and log-rank tests analyzed all time-to-event data. Confounding factors were included in Multivariable Cox proportional hazard models to identify independent prognostic factors. P-values <0.05 were considered statistically significant.

RESULTS

MNs incidence was 24.6%. MNs independently associated with decreased 5-year OS, DMFS, and PFS; not LRFS (P = 0.252). MN-positive patients gained significant survival benefit from IC in 5-year OS (88.4% vs. 66.0%) and PFS (76.4% vs. 53.5%), but not DMFS (83.1% vs. 69.9%, P = 0.145) or LRFS (89.9% vs. 77.8%, P = 0.140).

DATA CONCLUSION

MNs may independently stratify NPC risk and offer survival benefit from IC.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Blind Source Separation of Intermittent Frequency Hopping Sources over LOS and NLOS Channels

This paper studies blind source separation (BSS) for frequency hopping (FH) sources. These radio frequency (RF) signals are observed by a uniform linear array (ULA) over (i) line-of-sight (LOS), (ii) single-cluster, and (iii) multiple-cluster Spatial Channel Model (SCM) settings. The sources are stationary, spatially sparse, and their activity is intermittent and assumed to follow a hidden Markov model (HMM). BSS is achieved by leveraging direction of arrival (DOA) information through an FH estimation stage, a DOA estimation stage, and a pairing stage with the latter associating FH patterns with physical sources via their estimated DOAs. Current methods in the literature do not perform the association of multiple frequency hops to the sources they are transmitted from. We bridge this gap by pairing the FH estimates with DOA estimates and labeling signals to their sources, irrespective of their hopped frequencies. A state filtering technique, referred to as hidden state filtering (HSF), is developed to refine DOA estimates for sources that follow a HMM. Numerical results demonstrate that the proposed approach is capable of separating multiple intermittent FH sources.

MRI-Based Metastatic Nodal Number and Associated Nomogram Improve Stratification of Nasopharyngeal Carcinoma Patients: Potential Indications for Individual Induction Chemotherapy

BACKGROUND

Metastatic lymph nodal number (LNN) is associated with the survival of nasopharyngeal carcinoma (NPC); however, counting multiple nodes is cumbersome.

PURPOSE

To explore LNN threshold and evaluate its use in risk stratification and induction chemotherapy (IC) indication.

STUDY TYPE

Retrospective.

POPULATION

A total of 792 radiotherapy-treated NPC patients (N classification: N0 182, N1 438, N2 113, N3 59; training group: 396, validation group: 396; receiving IC: 390).

FIELD STRENGTH/SEQUENCE

T1-, T2- and postcontrast T1-weighted fast spin echo MRI at 1.5 or 3.0 T.

ASSESSMENT

Nomogram with (model B) or without (model A) LNN was constructed to evaluate the 5-year overall (OS), distant metastasis-free (DMFS), and progression-free survival (PFS) for the group as a whole and N1 stage subgroup. High- and low-risk groups were divided (above vs below LNN- or model B-threshold); their response to IC was evaluated among advanced patients in stage III/IV.

STATISTICAL TESTS

Maximally selected rank, univariate and multivariable Cox analysis identified the optimal LNN threshold and other variables. Harrell's concordance index (C-index) and 2-fold cross-validation evaluated discriminative ability of models. Matched-pair analysis compared survival outcomes of adding IC or not. A P value < 0.05 was considered statistically significant.

RESULTS

Median follow-up duration was 62.1 months. LNN ≥ 4 was independently associated with decreased 5-year DMFS, OS, and PFS in entire patients or N1 subgroup. Compared to model A, model B (adding LNN, LNN ≥ 4 vs <4) presented superior C-indexes in the training (0.755 vs 0.727) and validation groups (0.676 vs 0.642) for discriminating DMFS. High-risk patients benefited from IC with improved post-IC response and OS, but low-risk patients did not (P = 0.785 and 0.690, respectively).

CONCLUSIONS

LNN ≥ 4 is an independent risk stratification factor of worse survival in entire or N1 staging NPC patients. LNN ≥ 4 or the associated nomogram has potential to identify high-risk patients requiring IC.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: 4.

Establishment and validation of novel MRI radiomic feature-based prognostic models to predict progression-free survival in locally advanced rectal cancer

In locally advanced rectal cancer (LARC), an improved ability to predict prognosis before and after treatment is needed for individualized treatment. We aimed to utilize pre- and post-treatment clinical predictors and baseline magnetic resonance imaging (MRI) radiomic features for establishing prognostic models to predict progression-free survival (PFS) in patients with LARC. Patients with LARC diagnosed between March 2014 and May 2016 were included in this retrospective study. A radiomic signature based on extracted MRI features and clinical prognostic models based on clinical features were constructed in the training cohort to predict 3-year PFS. C-indices were used to evaluate the predictive accuracies of the radiomic signature, clinical prognostic models, and integrated prognostic model (iPostM). In total, 166 consecutive patients were included (110 vs. 56 for training vs. validation). Eleven radiomic features were filtered out to construct the radiomic signature, which was significantly related to PFS. The MRI feature-derived radiomic signature exhibited better prognostic performance than the clinical prognostic models (P = 0.007 vs. 0.077). Then, we proposed an iPostM that combined the radiomic signature with tumor regression grade. The iPostM achieved the highest C-indices in the training and validation cohorts (0.942 and 0.752, respectively), outperforming other models in predicting PFS (all P < 0.05). Decision curve analysis and survival curves of the validation cohort verified that iPostM demonstrated the best performance and facilitated risk stratification. Therefore, iPostM provided the most reliable prognostic prediction for PFS in patients with LARC.

Systematic construction and external validation of an immune-related prognostic model for nasopharyngeal carcinoma

BACKGROUND

We attempted to identify the most reliable immune-related index for predicting nasopharyngeal carcinoma (NPC) prognosis and to reveal its precise and integrated relationship with NPC progression.

METHOD

One thousand seven hundred and six patients with newly diagnosed NPC (1320 from the primary cohort and 386 from the validated cohort) from January 2010 to March 2014 were enrolled. Clinical features and 12 immune-related variables were analyzed.

RESULTS

A high absolute lymphocyte count (ALC; >3.2 × 10⁹ /L) correlated with a poor prognosis of patients with NPC. Significant OS differences were discovered between patients with high ALC and no ALC elevation (p < 0.05, in primary cohort), showing similar prognostic risk to patients with advanced NPC (p > 0.05, in validated cohort). ALC improved the predictive performance of the basic tumor-node-metastasis prognostic model (p = 0.025), which was reliably validated in the external independent cohort.

CONCLUSION

High ALC is a surrogate marker for improved prognostic risk stratification in NPC.

Modernising physician resource planning: a national interactive web platform for Canadian medical trainees

Background

Healthcare systems rely heavily upon human resources to ensure high-quality access to care for the general population. With significant health worker shortages predicted worldwide in the coming decades, maximizing the current workforce by means of a physician resource planning (PRP) strategy that ensures the right number, mix, and distribution of physicians to meet population needs is warranted. In Canada, there is an insufficient number of primary care providers, and disproportionately low numbers of specialist physicians in rural compared to urban regions. Currently, Canadian medical students are not effectively included in PRP strategy and lack the required information for career orientation to help rebalance the population’s workforce needs. This paper present the Health Human Resource (HHR) Platform, a comprehensive web tool that includes relevant workforce data to empower medical students in choosing a discipline based on both personal interests and social accountability.

Results

Physician workforce data, comments from Canadian residency program directors, and career planning resources were collected by the Canadian Federation of Medical Student’s (CFMS) HHR Task Force. This information was consolidated to create a national interactive platform that uses a map, comparison table, and trend graphs to illustrate over 500,000 unique data points from 37 datasets, including specific information and resources spanning 62 medical specialties from 2015 onwards. There was a 24.6% response rate for program director comments. During the first 4 months of the HHR Platform launch, there were 2434 different users, of which 985 were returning, with an average of 20.0 users per day spending on average 3 min on the platform.

Conclusions

The HHR Platform constitutes a national approach to PRP informing medical students on the mix and distribution of physicians needed to meet the future healthcare demands of the Canadian population.

Consensus of Minimally Invasive and Multidisciplinary Comprehensive Treatment for Hepatocellular Carcinoma - 2020 Guangzhou Recommendations

In China, the majority of patients with hepatocellular carcinoma (HCC) result from long-term infection of hepatitis B. Pathologically, HCC is characterized by rich blood supply, multicentric origins, early vascular invasion and intrahepatic metastasis. Therefore, HCC is not a local disease but a systemic disease at the beginning of its occurrence. For this reason, a comprehensive treatment strategy should be adopted in the management of HCC, including local treatments (such as surgical resection, radiofrequency ablation, microwave ablation, chemical ablation and cryoablation, etc.), organ-level treatments [such as transcatheter arterial infusion of chemotherapy and transcatheter arterial chemoembolization (TACE)], and systemic treatments (such as immunotherapy, antiviral therapy and molecular targeted therapy, etc.). This consensus sets forth the minimally-invasive and multidisciplinary comprehensive guideline of HCC, focusing on the following eight aspects (1) using hepaticarteriography, CT hepatic arteriography (CTHA), CT arterial portography (CTAP), lipiodol CT (Lp-CT), TACE-CT to find the intrahepatic lesion and make precise staging (2) TACE combined with ablation or ablation as the first choice of treatment for early stage or small HCC, while other therapies are considered only when ablation is not applicable (3) infiltrating HCC should be regarded as an independent subtype of HCC (4) minimally-invasive comprehensive treatment could be adopted in treating metastatic lymph nodes (5) multi-level subdivision of M-staging should be used for individualized treatment and predicting prognosis (6) HCC with severe hepatic decompensation is the only candidate criterion for liver transplantation (7) bio-immunotherapy, traditional Chinese medicine therapy, antiviral therapy, and psychosocial and psychopharmacological interventions should be advocated through the whole course of HCC treatment (8) implementation of multicenter randomized controlled trials of minimally-invasive therapy versus surgery for early and intermediate stage HCC is recommended.

Differences in Radiomics Signatures Between Patients with Early and Advanced T-Stage Nasopharyngeal Carcinoma Facilitate Prognostication

BACKGROUND

Accurately predicting the risk of death, recurrence, and metastasis of patients with nasopharyngeal carcinoma (NPC) is potentially important for personalized diagnosis and treatment. Survival outcomes of patients vary greatly in distinct stages of NPC. Prognostic models of stratified patients may aid in prognostication.

PURPOSE

To explore the prognostic performance of MRI-based radiomics signatures in stratified patients with NPC.

STUDY TYPE

Retrospective.

POPULATION

Seven hundred and seventy-eight patients with NPC (T1-2 stage: 298, T3-4 stage: 480; training cohort: 525, validation cohort: 253).

FIELD STRENGTH/SEQUENCE

Fast-spin echo (FSE) axial T1-weighted images, FSE axial T2-weighted images, contrast-enhanced FSE axial T1-weighted images at 1.5 T or 3.0 T.

ASSESSMENT

Radiomics signatures, clinical nomograms, and radiomics nomograms combining the radiomic score (Radscore) and clinical factors for predicting progression-free survival (PFS) were constructed on T1-2 stage patient cohort (A), T3-4 stage patient cohort (B), and the entire dataset (C).

STATISTICAL TESTS

Least absolute shrinkage and selection operator (LASSO) method was applied for radiomics modeling. Harrell's concordance indices (C-index) were employed to evaluate the predictive power of each model.

RESULTS

Among 4,410 MRI-extracted features, we selected 16, 16, and 14 radiomics features most relevant to PFS for Models A, B, and C, respectively. Only 0, 1, and 4 features were found overlapped between models A/B, A/C, and B/C, respectively. Radiomics signatures constructed on T1-2 stage and T3-4 stage patients yielded C-indices of 0.820 (95% confidence interval [CI]: 0.763-0.877) and 0.726 (0.687-0.765), respectively, which were larger than those on the entire validation cohort (0.675 [0.637-0.713]). Radiomics nomograms combining Radscore and clinical factors achieved significantly better performance than clinical nomograms (P < 0.05 for all).

DATA CONCLUSION

The selected radiomics features and prognostic performance of radiomics signatures differed per the type of NPC patients incorporated into the models. Radiomics models based on pre-stratified tumor stages had better prognostic performance than those on unstratified dataset.

LEVEL OF EVIDENCE

4 Technical Efficacy Stage: 5.

Grading Soft Tissue Involvement in Nasopharyngeal Carcinoma Using Network and Survival Analyses: A Two-Center Retrospective Study

BACKGROUND

Soft tissue involvement (STI) indicates poor prognosis in nasopharyngeal carcinoma (NPC). However, only a few studies have systematically assessed this extension using network analysis.

PURPOSE

To investigate the prognostic value of STI and to propose an improved STI grading system for NPC therapy.

STUDY TYPE

Retrospective study.

POPULATION

A total of 1225 consecutive patients with pathologically confirmed NPC treated with intensive-modulated radiotherapy from January 2010 to March 2014 were enrolled from two centers.

FIELD STRENGTH/SEQUENCE

T1- and T2-weighted imaging and enhanced T1-weighted imaging with fast spin echo sequence at 1.5 or 3.0 T.

ASSESSMENT

The levator veli palatini and tensor veli palatini involvement were graded "mild," prevertebral muscle involvement, "moderate," medial pterygoid, lateral pterygoid, and the infratemporal fossa involvement, "severe" STI. The above STI sites were evaluated separately by three radiologists using MRI images and graded using network analysis. Overall survival (OS) and progression-free survival (PFS) were assessed.

STATISTICAL TESTS

Kaplan-Meier method, Cox's proportional hazards model, and concordance index (C-index) were used.

RESULTS

Five-year OS and PFS rates between mild and moderate groups (90.5% vs. 81.7%, P < 0.05 and 82.9% vs. 72.5%, P < 0.05, respectively) and between moderate and severe groups (81.7% vs. 70.4%, P < 0.05 and 72.5% vs. 61.2%, P < 0.05, respectively) revealed significant differences. The C-index of the nomogram with STI grading was higher compared with current T-classification (OS 0.641 vs. 0.604, P < 0.05 and PFS 0.605 vs. 0.581, P < 0.05, respectively). Significant OS differences were observed between patients with severe STI who underwent induction chemotherapy (IC) and those who did not (84.5% vs. 70.7%, P < 0.05).

DATA CONCLUSION

STI grading was an independent prognostic factor for OS and PFS in NPC patients and it may be help to improve the accuracy in predicting survival outcomes. Patients with severe STI might benefit from IC to improve OS.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY: Stage 2.

Genomic epidemiology of Corynebacterium striatum from three regions of China: an emerging national nosocomial epidemic

BACKGROUND

Corynebacteritum straitum has been considered as an emerging multi-drug-resistant (MDR) pathogen. Isolation of MDR C. striatum as the only organism from respiratory samples from hospitalized patients is increasing in China.

AIM

To elucidate the genomic epidemiology and evolution of C. striatum in China.

METHODS

A total of 260 isolates from 2016 to 2018 were collected from three hospitals in three regions of China. Antibiotic sensitivity testing was performed on all isolates. Whole-genome sequencing was applied to all isolates to assess their genomic diversity and relationships and detect the presence of antimicrobial resistance genes (ARG) and ARG cassettes.

FINDINGS

Almost all isolates (96.2%, 250/260) showed multi-drug-resistance. Genome sequencing revealed four major lineages with lineage IV emerging as the epidemic lineage. Most of the diversity was developed in the last 6 years. Each hospital has its own predominant clones with potential spread between Hebei and Guangdong hospitals. Genomic analysis further revealed multiple antimicrobial resistance genes.

CONCLUSIONS

Our results suggested that four lineages of C. striatum have spread in parallel across China, causing persistent and extensive transmissions within hospitals. MDR C. striatum infection has become a national epidemic. Antibiotic-driven selection pressure may have played significant roles in forming persistent and predominant clones. Our data provide the basis for surveillance and prevention strategies to control the epidemic caused by MDR C. striatum.

Grading and prognosis of weight loss before and after treatment with optimal cutoff values in nasopharyngeal carcinoma

OBJECTIVES

Weight loss has been validated as a prognostic predictor of nasopharyngeal carcinoma (NPC); however, no global unitary indicator and criteria exist for the definition of weight loss as a prognostic factor. The aim of this study was to determine the most effective indicator for weight loss, evaluate its effect on the prognosis of NPC, and further propose a cutoff value to identify patients in need of nutritional care.

METHODS

This retrospective cohort analysis with a median follow-up of 62.3 mo included 681 newly diagnosed patients with NPC. Principal component analysis was performed to select the best continuous variable including weight loss (kg; value of weight loss [VWL]), percent weight loss (PWL), and body mass index loss (BMIL). Multivariable Cox regression analysis and multiple correspondence analysis were performed to select the best cutoff values by different cutoff methods including the median, receiver operating characteristic curve, and threshold searching.

RESULTS

PWL was the highest contributor to the prognosis of NPC compared with VWL and BMIL. Cutoff values of PWL (6.3 and 12.3%) were confirmed to be more important and were proposed to differentiate patients into low-, medium-, and high-risk NPC groups, with their 5-y progression-free survival (84.5 versus 77.9%, P = 0.046; 77.9 versus 67.3%, P = 0.046). PWL was an independent adverse prognostic factor (P = 0.002) for NPC.

CONCLUSIONS

PWL is a promising predictor for NPC, and cutoff values could be validated for nutritional risk grading in patients with NPC. These stratified criteria may help accelerate the extensive application of grading nutritional management in NPC therapy.

Staging of T2 and T3 nasopharyngeal carcinoma: Proposed modifications for improving the current AJCC staging system

Objectives

We aimed to reconstitute T2 and T3 stage classification in nasopharyngeal carcinoma (NPC) cases and verify its utility in clinical settings.

Materials and Methods

We enrolled 792 NPC patients. Cox proportional hazards model was used to compare the effect sizes (hazard ratio [HR]) of the cranial structure invasion on survival and select the structures for up‐staging or downstaging T2 and T3 NPC. The samples were reclassified and the survival curves for T2 and T3 stages were analyzed. The proposed new staging system was validated on an external sample (n = 433).

Results

Thirteen cranial structures were examined. American Joint Committee on Cancer (AJCC) T3 stage patients with the invasion of the base of the sphenoid (HR = 2.58, 95% CI = 1.16‐5.77) or base of the pterygoid (HR = 2.00, 95% CI = 0.84‐4.77) had significantly lower hazard ratios than T2 stage patients with the invasion of soft tissues in the bilateral parapharyngeal space (HR = 5.26, 95% CI = 2.02‐13.68) and single/bilateral carotid sheath (HR = 7.78, 95% CI = 3.06‐19.76). T3 stage with the invasion of the above‐mentioned bones was reclassified as T2, and T2 stage with the invasion of the above‐mentioned soft‐tissue structures was reclassified as T3. Survival analysis showed a significant difference between the reclassified T2 and T3 stages (P < 0.001). The results were replicated in the validation samples.

Conclusion

The proposed staging system for defining T2 and T3 stage NPC appears to be superior to the AJCC 8th edition. It could improve prognosis and optimize the treatment selection.

Prognostic Value of Nodal Matting on MRI in Nasopharyngeal Carcinoma Patients

BACKGROUND

Nodal (N) stage is one of the most important predictors for distant metastasis in nasopharyngeal carcinoma (NPC) patients. It may ignore potentially useful nodal features, such as nodal matting (three or more lymph nodes abutting together with the absence of intervening fat planes).

PURPOSE

To explore the prognostic value of nodal matting in NPC patients and construct a nomogram with nodal matting for predicting distant metastasis-free survival (DMFS).

STUDY TYPE

Retrospective.

POPULATION

In all, 792 NPC patients treated with intensity modulated radiation therapy from 2010 to 2013 were enrolled with 2:1 training (n = 527) and validation (n = 65) cohorts.

FIELD STRENGTH/SEQUENCE

T₁ - and T₂ -weighted imaging at 1.5 or 3.0T.

ASSESSMENT

Nodal matting and other nodal characteristics were assessed with MRI. MR images were evaluated separately by three radiologists. The association between nodal matting and DMFS was analyzed.

STATISTICAL TESTS

Univariate and multivariate analyses were performed using the Cox proportional hazards regression model. Nomograms were constructed from a multivariate logistic regression model with and without nodal matting. The predictive accuracy and discriminative ability of the nomograms were determined by concordance index (C-index) and calibration curves. The results were validated using bootstrap resampling and validation cohort.

RESULTS

The incidence of nodal matting was 24.6% (195/792) in all patients. In the training cohort, nodal matting was independently associated with DMFS (hazard ratio [HR] = 1.97 [1.05-3.69], P < 0.05). N1 patients with nodal matting had worse DMFS than N1 patients without (P < 0.05). However, no significant difference was observed when comparing N1 patients with nodal matting to N2 patients (P = 0.464). The C-index of the nomogram with nodal matting was higher than the nomogram without (0.717 vs. 0.699, P = 0.084).

DATA CONCLUSION

Nodal matting was an independent prognostic factor for DMFS in NPC patients. It may help to select patients at high risk of distant metastasis.

Prognostic significance of quantitative metastatic lymph node burden on magnetic resonance imaging in nasopharyngeal carcinoma: A retrospective study of 1224 patients from two centers

BACKGROUND AND PURPOSE

The number of metastatic lymph nodes (LNs) has been demonstrated to be an important prognosticator in some head and neck cancers. This study aimed to examine its prognostic value in nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

Patients with newly-diagnosed, non-distant metastatic NPC from two centers were enrolled in this study. According to the radiologic criteria for involved LNs, the number of positive LNs was assessed on MRI. Univariate and multivariate models were constructed to assess the association between the number of positive LNs and clinical outcomes. Exhaustive method was used to determine the cutoff values of the number of positive LNs.

RESULTS

In 1224 patients, the number of MRI-positive LNs was an independent risk factor for overall survival (OS), distant metastasis-free survival (DMFS), relapse-free survival (RFS), progression-free survival (PFS) and regional relapse-free survival (RRFS), surpassing other nodal factors. All the patients were divided into no, low (1-4 positive LNs), moderate (5-9 positive LNs) and high (>9 positive LNs) risk groups. The HRs of high-risk group exceeded the HRs of N3 classification for OS, DMFS, RFS, PFS and RRFS. On upgrading patients with more than 9 positive LNs from N2 to N3, the revised N-staging system showed a higher C-index compared to current N-staging system for predicting OS (0.747 vs. 0.741, P = 0.002), RFS (0.655 vs. 0.640, P = 0.015) and PFS (0.674 vs. 0.669, P = 0.035).

CONCLUSIONS

The number of MRI-positive LNs was a predominant independent prognostic factor for NPC patients' survival. It may be incorporated into the future N-staging system to improve its accuracy in predicting outcomes.

Predicting poor response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer: Model constructed using pre-treatment MRI features of structured report template

PURPOSE

To develop a predictive model with pre-treatment magnetic resonance imaging (MRI) findings of the structured report template and clinical parameters for poor responses prediction after neoadjuvant chemoradiotherapy (neoCRT) in locally advanced rectal cancers (LARC) patients.

METHOD

Patients with clinicopathologically confirmed LARC (training and validation datasets, n = 100 and 71, respectively) were enrolled. Patients' clinical data were retrospectively collected. MRI findings of the structured report template were analysed. The tumour regression grade (TRG) system as proposed by Mandard et al was used. Poor response was defined as TRG 3-5. Univariate logistic regression analysis and a lasso regression model were performed to select the significant predictive features from the training set. A nomogram was constructed based on a multivariable logistic regression analysis. Calibration, discrimination, and clinical usefulness of the nomogram were assessed. The calibrative and discriminative ability of our model were compared with those of models including the tumour-node-metastasis (TNM) stage and clinical factors.

RESULTS

The MRI-reported T4b stage, MRI-reported extramural venous invasion (EMVI) positivity, MRI-detected number of positive mesorectal lymph nodes (LNs) > 0, and preoperative oxaliplatin and capecitabine (CAPOX) chemotherapy regimen were incorporated into our nomogram. The nomogram showed good discrimination, with areas under the receiver operating characteristic (ROC) curves of 0·823 and 0·820 in the training and test sets, respectively, and good calibration in both datasets. The decision curve analysis confirmed that the nomogram was clinically useful. The calibrative and discriminative ability of our model were better than those models including the TNM stage and clinical factors.

CONCLUSION

A nomogram based on pre-treatment MRI features of the structured report template and clinical risk factors has potential for use as a non-invasive tool to preoperatively predict poor responses in LARC patients after neoCRT.

A160 THE EFFECT OF AN INSTRUCTIVE VIDEO ON THE BOWEL PREPARATION EXPERIENCE

Background

Over 26000 new cases of colorectal cancer (CRC) are diagnosed each year in Canada. This number has been decreased significantly by the implementation of CRC screening that includes removal of any polyps found during colonoscopies. Despite this, approximately 1 in 4 colonoscopies are inadequate for the detection of early neoplasms due to insufficient bowel preparation prior to the colonoscopy. Consequently, there is a need to improve patient adherence to the bowel preparation protocol. Previous research has shown that enhanced education, including the methods and rationale for bowel preparation prior to a colonoscopy, improves the quality of the bowel preparation.

Aims

We hypothesised that patients with access to a replayable video explaining the bowel preparation protocol and its importance would have increased satisfaction and noninferior bowel preparations.

Methods

100 patients undergoing programmatic screening colonoscopy were randomly assigned into one of two groups. The control group was given the standard presentation currently given to patients. The experimental group was given the same presentation and also given access to an educational video. This video is based on Alberta provincial bowel preparations which have been tested and evaluated. Participants in both groups were sent a survey one day after their colonoscopy. Subjects completed a modified version of the Outpatient and Ambulatory Surgery Consumer Assessment of Healthcare Providers and Systems survey with added questions designed to assess their satisfaction with the education they received on the bowel preparation. Bowel preparation quality was assessed on a 4-point Likert scale by the endoscopist.

Results

17 participants (10 female), aged 40–72 (Mage = 60) have enrolled in the study thus far; however, most have yet to have their colonoscopy. Initial results revealed that all participants had high levels of satisfaction with the presentation they were given. Those in the control group indicated that they would have liked to have had access to a video guide to the bowel preparation before their procedure. The participant in the experimental group indicated high levels of satisfaction with this video, noting that it provided important information not available from other sources. Information on the quality of their bowel preparations is pending.

Conclusions

The use of multimedia explanations of the bowel preparation has promise in improving patient satisfaction with the bowel preparation. Further studies may guide best methods for implementing a video assisted educational model to enhance colonoscopy preparation.

Funding Agencies

The first author received an Edna Wakefield Rowe Memorial Summer Research Award from the Faculty of Medicine & Dentistry at the University of Alberta to support this work.

Nodal grouping in nasopharyngeal carcinoma: prognostic significance, N classification, and a marker for the identification of candidates for induction chemotherapy

OBJECTIVES

This study aimed to evaluate the value of nodal grouping (NG), defined as the presence of at least three contiguous lymph nodes (LNs) within one LN region, in staging and management of patients with non-metastatic nasopharyngeal carcinoma (NPC).

METHODS

MR images were reviewed to evaluate LN variables, including NG. The Kaplan-Meier method and multivariate Cox regression models evaluated the association between the variables and survival. Harrell's concordance index (C-index) was used to measure the performance of prognostic models. The outcome of induction chemotherapy (IC) in patients with and without NG was compared using matched-pair analysis.

RESULTS

In 1224 patients enrolled, NG was found to be an independent prognostic factor for overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS), and regional recurrence-free survival. The hazard ratio and 95% confidence interval (CI) of NG for OS (3.86, 2.09-7.12) were higher than those of stage N2 (3.54, 1.89-6.70). On upgrading patients with NG from stages N1 to N2, the revised N staging yielded a higher C-index compared to the American Joint Committee on Cancer system in predicting PFS (0.664 vs. 0.658, p = 0.022) and DMFS (0.699 vs. 0.690, p = 0.005). Results of the matched-pair analysis revealed that for patients with NG in stages N1 and N2, IC was correlated with improved OS (p = 0.022), PFS (p = 0.007), and DMFS (p = 0.021).

CONCLUSIONS

NG is a significant prognostic factor for patients with NPC. Patients with NG may be upgraded from stages N1 to N2. NG was also a marker for identifying patients who would benefit from IC.

KEY POINTS

• Nodal grouping, defined as the presence of at least three contiguous LNs within one LN region on MRI, was identified as a significant prognostic factor. • In patients with nasopharyngeal carcinoma, nodal grouping may influence lymph node staging. • Nodal grouping was a marker for identifying patients who may benefit from induction chemotherapy.

P1019Validation of a risk score to predict the need for pacemaker implantation after transcatheter aortic valve replacement

Background

New conduction abnormalities necessitating pacemaker implantation (PMI) is a common occurrence after TAVR. There is an increased rate of PMI in the those receiving the most contemporary implanted valve, the Edwards Sapien-3 (S3), compared to prior generation balloon expandable valves. We previously described predictors of PMI in a large cohort. Herein we sought to validate these predictors of PMI in a subsequent validation cohort.

Methods

We evaluated all patients undergoing first time elective TAVR with S3 at our institution (n=326). We developed a risk score based on a predictive model we have previously described. Patients received one point for each of the following: history of syncope, oversizing of the valve >16%, baseline right bundle branch block morphology, and two points for a QRS duration >115 ms. We performed regression analysis of the risk score and need for PMI. We also evaluated the performance of the risk score using ROC analysis.

Results

Thirty patients (8%) of the total cohort had need for PMI after S3 implantation. Those with PMI had a higher rate of pre-existing infra-nodal conduction system disease – including QRS duration >115ms (57% vs. 20%, p<0.001) and right bundle branch block (RBBB) morphology (47% vs. 10%, p<0.001) - as well as more frequent valve oversizing >15.7% (47% vs. 23%, p<0.01). There was no significant difference in a history of syncope (10% vs. 8%, p=0.72) between groups. The PMI risk score had an area under the curve of 0.753 on ROC analysis. The PMI risk score was significantly associated with PMI (OR 2.37; 95% CI [1.64–3.34], p<0.001).

Rate of PMI Stratified by Risk Score

Conclusions

The PMI risk score was strongly predictive of the need for PMI after implantation of the S3 valve in a large validation cohort. The PMI risk score performed well in sensitivity analysis. This PMI risk score represents a simple tool to help further risk stratify patients being considered for TAVR.

Translation and validation of a Chinese version of the Warwick-Edinburgh Mental Well-being Scale with undergraduate nursing trainees

WHAT IS KNOWN ON THE SUBJECT?: Warwick-Edinburgh Mental Well-being Scale (WEMWBS) which is a measurement of mental health and well-being, was translated into Chinese to assess the reliability and validity in a sample of undergraduate nursing trainees in Wenzhou. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: Currently, there is no a reliable assessment tool to systematically evaluate mental well-being in mainland China. Therefore, we undertook the translation and cultural adaptation of the WEMWBS and tested the scale's reliability and validity. The reliability and validity of the Chinese version of the Short Warwick-Edinburgh Mental Well-being Scale have been demonstrated in Hong Kong, but the WEMWBS has not been validated in mainland China in either clinical or non-clinical settings. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: It might provide a reliable quantitative tool to evaluate mental well-being in non-clinical settings, which has important implications for mental health nursing. In future,it might be a reliable quantitative tool for evaluating mental well-being in other population such as hospitalized patients to improve their life quality.

ABSTRACT

Introduction There is growing interest worldwide in the evaluation of positive mental health and wellbeing. Aim This study was to translate the Warwick-Edinburgh Mental Well-being Scale (WEMWBS) into Chinese and assess the reliability and validity of this scale in a sample of undergraduate nursing trainees. Methods A forward and backward translation protocol was used to translate the scale into Chinese. The psychometric properties of the C-WEMWBS, such as internal consistency reliability, test-retest reliability and factorial validity, were analysed. Results All 14 items of the initial C-WEMWBS were rated as conceptually equivalent to those of the original version. Confirmatory factor analysis indicated the emergence of a single factor. The psychometric properties of the C-WEMWBS were satisfactory, with an internal consistency reliability of .94 and a test-retest reliability of .83. The item-total correlations ranged from .66 to .83. There was a moderate relationship (r = .52) between the C-WEMWBS and the WHO-5. Implications for practice This was the first Chinese version of the WEMWBS to be developed and psychometrically assessed with a sample of undergraduate nursing trainees. It provides a reliable quantitative tool to evaluate mental well-being in non-clinical settings, which has important implications for mental health nursing.

CT-Guided Percutaneous Step-by-Step Radiofrequency Ablation for the Treatment of Carcinoma in the Caudate Lobe

The location of the caudate lobe and its complex anatomy make caudate lobectomy and radiofrequency ablation (RFA) under ultrasound guidance technically challenging. The objective of the exploratory study was to introduce a novel modality of treatment of lesions in caudate lobe and discuss all details with our experiences to make this novel treatment modality repeatable and educational. The study enrolled 39 patients with liver caudate lobe tumor first diagnosed by computerized tomography (CT) or magnetic resonance imaging (MRI). After consultation of multi-disciplinary team, 7 patients with hepatic caudate lobe lesions were enrolled and accepted CT-guided percutaneous step-by-step RFA treatment. A total of 8 caudate lobe lesions of the 7 patients were treated by RFA in 6 cases and RFA combined with percutaneous ethanol injection (PEI) in 1 case. Median tumor diameter was 29 mm (range, 18-69 mm). A right approach was selected for 6 patients and a dorsal approach for 1 patient. Median operative time was 64 min (range, 59-102 min). Median blood loss was 10 mL (range, 8-16 mL) and mainly due to puncture injury. Median hospitalization time was 4 days (range, 2-5 days). All lesions were completely ablated (8/8; 100%) and no recurrence at the site of previous RFA was observed during median 8 months follow-up (range 3-11 months). No major or life-threatening complications or deaths occurred. In conclusion, percutaneous step-by-step RFA under CT guidance is a novel and effective minimally invasive therapy for hepatic caudate lobe lesions with well repeatability.

[Cytokine-induced killer cells transfusion following minimally invasive and interventional therapy for early-stage hepatocellular carcinoma:a long-term study]

OBJECTIVE

To evaluate the safety and efficiency of transcatheter arterial chemoembolization (TACE) and subsequent radiofrequency ablation (RFA) combined with cytokine-induced killer (CIK) cells transfusion for early-stage hepatocellular carcinoma (HCC).

METHODS

A retrospective analysis was conducted for 63 early-stage HCC patients who were treated with TACE and sequential RFA in this hospital between July 2001 and January 2012. These patients were divided into two groups: TACE+RFA+CIK (31 patients) and TACE+RFA (32 patients). Overall survival (OS), progression-free survival (PFS) and adverse events were compared between two groups.

RESULTS

The median OS and PFS in the TACE+RFA+CIK group were significantly longer than those in TACE+RFA group (OS: 107.5 vs 61.4 months, respectively, P=0.038; PFS: 43.0 vs 30.0 months respectively, P=0.024).The 3-, 5- and 10-year cumulative overall survival rates in the TACE+RFA+CIK group were higher than those in the TACE+RFA group (93.3%, 77.7% and 35.4% vs 76.7%, 57.7% and 29.3%, respectively). The 1-, 3-, and 5-year cumulative progression-free survival rates were also higher in the TACE+RFA+CIK group (93.5%, 66.4% and 28.4% vs 84.4%, 38.5% and 0.1%, respectively). No serious complications were observed in both groups.

CONCLUSION

This study suggests that CIK cells transfusion is safe, feasible, and superior in prolonging the OS and PFS time of early-stage HCC. However, any conclusions must be confirmed by more clinical studies.

1.0 T open-configuration magnetic resonance-guided microwave ablation of pig livers in real time

The current fastest frame rate of each single image slice in MR-guided ablation is 1.3 seconds, which means delayed imaging for human at an average reaction time: 0.33 seconds. The delayed imaging greatly limits the accuracy of puncture and ablation, and results in puncture injury or incomplete ablation. To overcome delayed imaging and obtain real-time imaging, the study was performed using a 1.0-T whole-body open configuration MR scanner in the livers of 10 Wuzhishan pigs. A respiratory-triggered liver matrix array was explored to guide and monitor microwave ablation in real-time. We successfully performed the entire ablation procedure under MR real-time guidance at 0.202 s, the fastest frame rate for each single image slice. The puncture time ranged from 23 min to 3 min. For the pigs, the mean puncture time was shorted to 4.75 minutes and the mean ablation time was 11.25 minutes at power 70 W. The mean length and widths were 4.62 ± 0.24 cm and 2.64 ± 0.13 cm, respectively. No complications or ablation related deaths during or after ablation were observed. In the current study, MR is able to guide microwave ablation like ultrasound in real-time guidance showing great potential for the treatment of liver tumors.

M1 stage subdivision and treatment outcome of patients with bone-only metastasis of nasopharyngeal carcinoma

BACKGROUND

The current M1 stage in nasopharyngeal carcinoma (NPC) does not differentiate patients based on metastatic site and number of metastases. This study aims to subdivide the M1 stage of NPC patients with bone-only metastases and to identify the patients who may benefit from combined chemoradiotherapy (CRT).

METHODS

Between 1998 and 2007, 312 patients diagnosed with bone-only metastasis at Sun Yat-sen University Cancer Center were enrolled. Various possible subdivisions of M1 stage were considered, including by the time order of metastasis (synchronous vs. metachronous), involvement of specific bone metastatic site, the number of metastatic sites, and the number of metastases. The correlation of the subdivisions of M1 stage with overall survival (OS) was determined by Cox regression.

RESULTS

The median OS was 23.4 months. Patients with more than three metastatic sites had significantly poorer OS than patients with three or fewer metastatic sites (16.2 vs. 32.4 months; p < .001). Metastasis to the spine was significantly associated with unfavorable OS (20.4 vs. 37.9 months; p < .001). Multivariate analysis showed that number of metastatic sites (more than three vs. three or fewer), spine involvement (present vs. absent), and treatment modality (CRT vs. chemotherapy or radiotherapy only) were independent prognostic factors for OS. In stratified analysis, compared with chemotherapy or radiotherapy alone, combined chemoradiotherapy could significantly benefit the patients with single bone metastasis (hazard ratio: 0.21; 95% confidence interval: 0.09-0.50).

CONCLUSION

Metastasis to the spine and having more than three bone metastatic sites are independent unfavorable predictors for OS in NPC patients with bone-only metastasis. Combined chemoradiotherapy should be considered for patients with single bone metastasis.

Gene therapy for unresectable hepatocellular carcinoma using recombinant human adenovirus type 5

The objective of this study was to assess the clinical efficacy of genetically engineered recombinant human adenovirus type 5 (rhAd5) plus transcatheter arterial chemoembolization in patients with unresectable hepatocellular carcinoma (HCC). Data from two groups of patients with unresectable HCC were retrospectively reviewed. One group included 149 patients treated with rhAd5 injection, and the other included 150 control patients without gene therapy. Differences in short-term treatment effectiveness and adverse events were recorded and compared between the two groups. Our results indicated that for patients with higher tumor staging in the treatment group, the overall response rate and the disease control rate were higher than those in the control group, but not statistically significant (P > 0.05). The total progression free survival (PFS) and overall survival (OS) were significantly longer in the treatment group than the control group (240 vs. 196 days, P < 0.05; and 1,526 vs. 1,236 days, P = 0.000; respectively). The overall incidence rate of treatment-related adverse effects was similar (P > 0.05). No serious complications were observed. In conclusion, this study suggests that rhAd5 is a safe, effective gene therapy that prolongs the PFS and OS time of patients with unresectable HCC.

[The analysis of atrial cells conductivity based on epicardial mapping data of dog]

This paper discusses the law of atrial electrical activity propagation (the timing of signal and the conduction velocity) under the sinus rhythm before and after AF caused by high-frequency electrical stimulation. The paper analyzes how different doses of acetylcholine affect the conductivity of the atrial cells of dogs. This result can also help the diagnoses and treatment of human's AF.

Organizing and managing personal electronic files

This article deals with the organization and management of the computer files handled by mechanical engineers on their personal computers. In engineering organizations, a wide variety of electronic files (documents) are necessary to support both business processes and the activities of design and manufacture. Whilst a large number of files and hence information is formally archived, a significant amount of additional information and knowledge resides in electronic files on personal computers. The widespread use of these personal information stores means that all information is retained. However, its reuse is problematic for all but the individual as a result of the naming and organization of the files. To begin to address this issue, a study of the use and current practices for managing personal electronic files is described. The study considers the fundamental classes of files handled by engineers and analyses the organization of these files across the personal computers of 40 participants. The study involves a questionnaire and an electronic audit. The results of these qualitative and quantitative elements are used to elicit an understanding of the practices and requirements of engineers for managing personal electronic files. A potential scheme for naming and organizing personal electronic files is discussed as one possible way to satisfy these requirements. The aim of the scheme is to balance the personal nature of data storage with the need for personal records to be shared with others to support knowledge reuse in engineering organizations. Although this article is concerned with mechanical engineers, the issues dealt with are relevant to knowledge-based industries and, in particular, teams of knowledge workers.

Oxidative damage in age-related macular degeneration

Epidemiologic studies have suggested that elderly patients who consumed diets rich in antioxidants throughout their lives are less likely to be afflicted with age-related macular degeneration (AMD). This led to the Age-Related Eye Disease Study, which showed that supplements containing antioxidant vitamins and zinc reduce the risk of progression to severe stages of AMD. Despite these data that indirectly implicate oxidative damage in the pathogenesis of AMD, there has not been any direct demonstration of increased oxidative damage in the retinas of patients with AMD. In this study, we used biomarkers of oxidative damage in postmortem eyes from patients with AMD and comparably aged patients without AMD to directly assess for oxidative damage. Sections from 4 eyes with no pathologic features of AMD showed no immunofluorescent staining for markers of oxidative damage, while sections from 8 of 12 eyes with advanced geographic atrophy showed evidence of widespread oxidative damage in both posterior and anterior retina. Only 2 of 8 eyes with choroidal neovascularization and 2 of 16 eyes with diffuse drusen and no other signs of AMD showed evidence of oxidative damage. These data suggest that widespread oxidative damage occurs in the retina of some patients with AMD and is more likely to be seen in patients with advanced geographic atrophy. This does not rule out oxidative damage as a pathogenic mechanism in patients with CNV, but suggests that a subpopulation of patients with geographic atrophy may have a major deficiency in the oxidative defense system that puts the majority of cells in the retina at risk for oxidative damage.

The antitumor activity of TRAIL and IL-24 with replicating oncolytic adenovirus in colorectal cancer

Melanoma differentiation associated gene-7 (Mda-7)/IL-24 was previously cloned into ZD55 (an adenovirus with E1B55 deleted) to form ZD55-IL-24, which had much better antitumor effect than Ad-IL-24. According to its good antitumor properties, ZD55-IL-24 has been used in preclinical studies. But ZD55-IL-24 alone still could not completely eradicate established tumors in all nude mice. It was reported that IL-24 could induce and enhance the activity of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) (a member of tumor necrosis factor (TNF) superfamily). Accordingly, the combined use of ZD55-IL-24 and ZD55-TRAIL was carried out in this study. Treatment with both ZD55-IL-24 and ZD55-TRAIL could induce more significant apoptosis in cancer cells in vitro compared with ZD55-IL-24 or ZD55-TRAIL alone. The combination of the two replicative adenoviruses had better antitumor activity in vivo than that of single oncolytic adenovirus and led to complete eradication of xenograft tumors in all treated mice. Upregulation of TRAIL was observed in tumor cells infected with ZD55-IL-24 and studies of the apoptotic cascade regulators indicate that ZD55-IL-24 could further enhance the activation of apoptosis through the TNF family of death receptors. We demonstrated for the first time the potential therapeutic effect of combined ZD55-IL-24 with ZD55-TRAIL for the targeted therapy of cancer.

Structural and functional analysis of a truncated form of Saccharomyces cerevisiae ATP sulfurylase: C-terminal domain essential for oligomer formation but not for activity

ATP sulfurylase catalyzes the first step in the activation of sulfate by transferring the adenylyl-moiety (AMP approximately ) of ATP to sulfate to form adenosine 5'-phosphosulfate (APS) and pyrophosphate (PP(i)). Subsequently, APS kinase mediates transfer of the gamma-phosphoryl group of ATP to APS to form 3'-phosphoadenosine 5'-phosphosulfate (PAPS) and ADP. The recently determined crystal structure of yeast ATP sulfurylase suggests that its C-terminal domain is structurally quite independent from the other domains, and not essential for catalytic activity. It seems, however, to dictate the oligomerization state of the protein. Here we show that truncation of this domain results in a monomeric enzyme with slightly enhanced catalytic efficiency. Structural alignment of the C-terminal domain indicated that it is extremely similar in its fold to APS kinase although not catalytically competent. While carrying out these structural and functional studies a surface groove was noted. Careful inspection and modeling revealed that the groove is sufficiently deep and wide, as well as properly positioned, to act as a substrate channel between the ATP sulfurylase and APS kinase-like domains of the enzyme.

Structure of human DNMT2, an enigmatic DNA methyltransferase homolog that displays denaturant-resistant binding to DNA

DNMT2 is a human protein that displays strong sequence similarities to DNA (cytosine-5)-methyltransferases (m(5)C MTases) of both prokaryotes and eukaryotes. DNMT2 contains all 10 sequence motifs that are conserved among m(5)C MTases, including the consensus S:-adenosyl-L-methionine-binding motifs and the active site ProCys dipeptide. DNMT2 has close homologs in plants, insects and Schizosaccharomyces pombe, but no related sequence can be found in the genomes of Saccharomyces cerevisiae or Caenorhabditis elegans. The crystal structure of a deletion mutant of DNMT2 complexed with S-adenosyl-L-homocysteine (AdoHcy) has been determined at 1.8 A resolution. The structure of the large domain that contains the sequence motifs involved in catalysis is remarkably similar to that of M.HHAI, a confirmed bacterial m(5)C MTase, and the smaller target recognition domains of DNMT2 and M.HHAI are also closely related in overall structure. The small domain of DNMT2 contains three short helices that are not present in M.HHAI. DNMT2 binds AdoHcy in the same conformation as confirmed m(5)C MTases and, while DNMT2 shares all sequence and structural features with m(5)C MTases, it has failed to demonstrate detectable transmethylase activity. We show here that homologs of DNMT2, which are present in some organisms that are not known to methylate their genomes, contain a specific target-recognizing sequence motif including an invariant CysPheThr tripeptide. DNMT2 binds DNA to form a denaturant-resistant complex in vitro. While the biological function of DNMT2 is not yet known, the strong binding to DNA suggests that DNMT2 may mark specific sequences in the genome by binding to DNA through the specific target-recognizing motif.

Functional roles of the conserved threonine 250 in the target recognition domain of HhaI DNA methyltransferase

DNA cytosine-5-methyltransferase HhaI recognizes the GCGC sequence and flips the inner cytosine out of DNA helix and into the catalytic site for methylation. The 5'-phosphate of the flipped out cytosine is in contact with the conserved Thr-250 from the target recognition domain. We have produced 12 mutants of Thr-250 and examined their methylation potential in vivo. Six active mutants were subjected to detailed biochemical and structural studies. Mutants with similar or smaller side chains (Ser, Cys, and Gly) are very similar to wild-type enzyme in terms of steady-state kinetic parameters k(cat), K(m)(DNA), K(m)(AdoMet). In contrast, the mutants with bulkier side chains (Asn, Asp, and His) show increased K(m) values for both substrates. Fluorescence titrations and stopped-flow kinetic analysis of interactions with duplex oligonucleotides containing 2-aminopurine at the target base position indicate that the T250G mutation leads to a more polar but less solvent-accessible position of the flipped out target base. The x-ray structure of the ternary M. HhaI(T250G).DNA.AdoHcy complex shows that the target cytosine is locked in the catalytic center of enzyme. The space created by the mutation is filled by water molecules and the adjacent DNA backbone atoms dislocate slightly toward the missing side chain. In aggregate, our results suggest that the side chain of Thr-250 is involved in constraining the conformation the DNA backbone and the target base during its rotation into the catalytic site of enzyme.

Cell cycle-dependent proteolysis and ectopic overexpression of cyclin B1 in tobacco BY2 cells

Activation of cyclin B/Cdc2 kinase complex triggers entry into mitosis in all eukaryotic cells. Although cyclin gene expression has been extensively studied in plants, not much is known at the level of the protein stability and function. Here, we demonstrated by using the highly synchronizable tobacco BY2 cell culture, that endogenous cyclin B1 protein undergoes cell cycle-dependent proteolysis and is stabilized when the spindle checkpoint has been activated. Furthermore, we established transgenic tobacco BY2 cell cultures expressing under the control of an inducible promoter, cyclin B1 protein as well as its non-degradable form as fusion proteins with GFP and found that the ectopic expression of these proteins did not dramatically disturb the cell cycle progression. These results indicate that, to a certain extent, cell cycle exit is possible without cyclin B1 proteolysis.

Comparative fourier transform infrared and circular dichroism spectroscopic analysis of alpha1-proteinase inhibitor and ovalbumin in aqueous solution

Alpha1-proteinase inhibitor (alpha1Pi) and ovalbumin are both members of the serpin superfamily. They share about a 30% sequence identity and exhibit great similarity in their three-dimensional structures. However, no apparent functional relationship has been found between the two proteins. Unlike alpha1Pi, ovalbumin shows no inhibitory effect to serine proteases. To see whether or not a conformational factor(s) may contribute to the functional difference, we carried out comparative analysis of the two proteins' secondary structure, thermal stability, and H-D exchange using FT-IR and CD spectroscopy. FT-IR analysis reveals significant differences in the amide I spectral patterns of the two proteins. Upon thermal denaturation, both proteins exhibit a strong low-wavenumber beta-sheet band at 1624 cm(-1) and a weak high-wavenumber beta-sheet band at 1694 cm(-1), indicative of intermolecular aggregate formation. However, the midpoint of the thermal-induced transition of alpha1Pi (approximately 55 degrees C) is 18 degrees C lower than that of ovalbumin (approximately 73 degrees C). The thermal stability analysis provides new insight into the structural changes associated with denaturation. The result of H-D exchange explains some puzzling spectral differences between the two proteins in D2O reported previously.

Entrapping intermediates of thermal aggregation in alpha-helical proteins with low concentration of guanidine hydrochloride

Aggregation of proteins is a problem with serious medical implications and economic importance. To develop strategies for preventing aggregation, the mechanism(s) and pathways by which proteins aggregate must be characterized. In this study, the thermally induced aggregation processes of three alpha-helix proteins (myoglobin, cytochrome c, and lysozyme) in the presence and absence of 1.0 m guanidine hydrochloride (GdnHCl) were investigated by means of infrared spectroscopy. In the absence of GdnHCl, intensities of the alpha-helix bands (approximately 1656 cm(-1)) decrease as a function of temperature at above 50 degrees C. With myoglobin and cytochrome c, the loss of helix bands was accompanied by the appearance of two new bands at 1694 and 1623 cm(-1), indicative of the formation of intermolecular beta-sheet aggregates. For lysozyme, bands indicative of intermolecular beta-sheet aggregates did not appear in any significant intensity. In the presence of 1.0 m GdnHCl, two major intermediate states rich in 3(10)-helix (represented by the band at 1663 cm(-1)) and beta-turn structure (represented by the band at 1667 cm(-1)), respectively, were observed. These findings demonstrated that IR spectroscopic studies of protein aggregation using a combination of thermal and chemical denaturing factors could provide a means to populate and characterize aggregation intermediates.

Antifungal, antimitotic and anti-HIV-1 agents from the roots of Wikstroemia indica

With guidance of Pyricularia oryzae bioassay, daphnoretin (1), (+)-nortrachelogenin (2), genkwanol A (3), wikstrol A (4), wikstrol B (5) and daphnodorin B (6) were isolated from the roots of Wikstroemia indica. Compounds 1-6 induced morphological deformation of P. oryzae mycelia with MMDC values of 68.4 +/- 1.3, 31.3 +/- 1.8, 45.8 +/- 0.5, 70.1 +/- 2.4, 52.3 +/- 0.9 and 73.7 +/- 1.6 microM, respectively. Compounds 3-6 showed moderate activity against microtubule polymerization with IC50 values of 112 +/- 4, 131 +/- 3, 184 +/- 6 and 142 +/- 2 microM in vitro, respectively. Compounds 2, 3, 5 and 6 were moderately active against HIV-1 in vitro. The findings of bioactivity of 1-6 support the antifungus, antimitosis and anti-HIV-1 uses for W. indica roots.

A novel calmodulin-like protein gene in rice which has an unusual prolonged C-terminal sequence carrying a putative prenylation site

A rice cDNA encoding a novel calmodulin-like protein was identified. It has 38 additional amino acids at the C-terminus of a complete, typical calmodulin (CaM) sequence of 149 amino acids. The four C-terminal amino acid residues form a CAAL motif which could be a site for protein prenylation and may subsequently cause the protein to become membrane associated. RT-PCR analysis confirmed that such a combined protein gene truly exists in rice. Sequence analysis of its genomic counterpart showed that there is an intron located at junction of the normal CaM sequence and the 38 C-terminal amino acids. This introduces a potential stop codon for normal CaM if an alternative splicing mechanism is involved. Southern blot analysis of rice genomic DNA revealed that there is only one locus for this gene. The northern blot analysis showed that this gene is highly expressed in rice roots, shoots and flowers. The distribution of this protein demonstrates the functional importance of this novel CaM-like protein in rice.

Preparation and Morphology Studies of Core-Shell Type Waterborne Polyacrylate-Polyurethane Microspheres

Core-shell type waterborne polyacrylate-polyurethane microspheres in which polyurethane acts as the shell and acrylic polymer as the core were prepared. Hydroxyethyl acrylate and adipic dihydrazide were used as cross-linking agents introduced to the ends of the shell molecular chains, and two kinds of cross-linked structures between the core and the shell were formed. The photon correlation spectroscopy studies indicate that all the microspheres present continuous particle-size distributions and their mean particle sizes are smaller than 200 nm. The transmission electron photographs reveal that there are obvious core-shell structures for the noncross-linked type microsphere particles and different cross-linked networks between the core and shell for the two kinds of cross-linked type microsphere particles. These microspheres possess excellent storage stability, water resistance, and coating properties. Copyright 1999 Academic Press.

Antineoplastic agents. III: Steroidal glycosides from Solanum nigrum

By bioactivity-guided fractionation, three known steroidal glycosides, beta 2-solamargine (1), solamargine (2), and degalactotigonin (3), were isolated from Solanum nigrum. Compounds 1-3 induced morphological abnormality in Pyricularia oryzae mycelia with MMDC (minimum morphological deformation concentration) values of 63.0, 38.5, and 97.2 microM, respectively. This is the first report on the isolation of 1 from this species and on the cytotoxicity of 1-3 on six cultured human solid tumor cell lines HT-29 (colon), HCT-15 (colon), LNCaP (prostate), PC-3 (prostate), T47D (breast), and MDA-MB-231 (breast) in vitro. The cytotoxic assay indicated that 2 is the main antineoplastic agent in S. nigrum. The structures of 1-3 were elucidated on the basis of chemical evidence and spectral analysis, especially by 2D-NMR analysis.

Use of infrared spectroscopy to assess secondary structure of human growth hormone within biodegradable microspheres

The purpose of this study was to test the utility of infrared (IR) spectroscopy to determine protein secondary structure in biodegradable microspheres. Encapsulation of proteins within biodegradable polymers, [e.g. poly(lactic-co-glycolic acid) (PLGA)] for controlled drug release has recently been the subject of intense research effort. The ability to assess protein integrity after microsphere production is necessary to successfully produce microspheres that release native proteins. We used IR spectroscopy, a noninvasive method-as opposed to conventional organic solvent extraction or in vitro release at elevated temperature-to assess the secondary structure of recombinant human growth hormone (rhGH) within dry and rehydrated microspheres. PLGA microspheres containing rhGH with different excipients were prepared by a conventional double-emulsion method. The protein IR spectra indicated that the encapsulation process could perturb the structure of rhGH and that excipients could inhibit this damage to varying degrees. A strong positive correlation was found between intensity of the dominant alpha-helical band in the spectra of rhGH in rehydrated microspheres and the percent monomer released from microspheres during incubation in buffer. We also studied microspheres prepared with zinc-precipitated rhGH. The addition of Zn2+ during microsphere processing partially inhibited protein unfolding and fostered complete refolding of rhGH upon rehydration. In conclusion, IR spectroscopy can serve as a valuable tool to assess protein structure within both dried and rehydrated microspheres.