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Gudina AT, Kamen C, Hardy SJ, Kehoe L, Culakova E, Cupertino AP. Revisiting the lung cancer screening eligibility criteria to promote equity for Black individuals. Lung Cancer 2024; 191:107539. [PMID: 38552545 DOI: 10.1016/j.lungcan.2024.107539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/13/2024] [Accepted: 03/18/2024] [Indexed: 05/01/2024]
Abstract
BACKGROUND Early detection using low-dose computed tomography reduces lung-cancer-specific mortality by 20% among high-risk individuals. Blacks are less likely than Whites to meet lung cancer screening (LCS) criteria under both the former and the updated United States Preventive Services Task Force (USPSTF) guidelines. The purpose of this study was to assess racial disparities in LCS eligibility and to propose tailored eligibility criteria for Blacks to enable equitable screening rate between Whites and Blacks. METHODS Data for this study were obtained from the Behavioral Risk Factor Surveillance System (2017-2021). 101,552 subjects were included in the final analysis. By employing a systematic approach, we sought cut-off points at which Blacks were equally likely as Whites to be eligible for LCS. We evaluated the minimum age and smoking pack-years for Blacks while we retained the 2021 USPSTF criteria for Whites. The final decision was based on the minimum Wald's Chi-square statistics. RESULTS The model we employed identified cut-off points at which Blacks were equally likely as Whites to be eligible for LCS. Retaining the 2021 USPSTF criteria for Whites, the model discovered a new pair of points for Blacks by reducing the minimum age to 43 years and decreasing the cumulative number of cigarettes smoked to 15 pack-years. Based on these cut-off points, we created tailored criteria for Blacks. Under the tailored criteria, Blacks (OR: 1.00; 95 %CI: 0.88-1.14) had the same odds of eligibility for LCS as Whites. The odds of eligibility for LCS by sex under the tailored criteria did not differ significantly for Black men (OR: 1.02; 95 %CI: 0.85-1.24) and Black women (OR: 0.95; 95 %CI: 0.81-1.12) compared to their respective White counterparts. CONCLUSIONS These tailored criteria for Blacks eliminate the disparities between Blacks and Whites in LCS eligibility. Future studies should test the sensitivity and specificity of these tailored criteria.
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Affiliation(s)
- Abdi T Gudina
- Department of Public Health Sciences at the University of Rochester, School of Medicine and Dentistry, NY, United States.
| | - Charles Kamen
- Division of Supportive Care in Cancer in the Department of Surgery at the University of Rochester, School of Medicine and Dentistry and the James P. Wilmot Cancer Institute at the University of Rochester, School of Medicine and Dentistry, NY, United States
| | - Sara J Hardy
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, United States; Department of Neurology, University of Rochester Medical Center, Rochester, NY, United States
| | - Lee Kehoe
- Division of Supportive Care in Cancer in the Department of Surgery at the University of Rochester, School of Medicine and Dentistry and the James P. Wilmot Cancer Institute at the University of Rochester, School of Medicine and Dentistry, NY, United States
| | - Eva Culakova
- Division of Supportive Care in Cancer in the Department of Surgery at the University of Rochester, School of Medicine and Dentistry and the James P. Wilmot Cancer Institute at the University of Rochester, School of Medicine and Dentistry, NY, United States
| | - Ana-Paula Cupertino
- Surgical Health Outcomes and Reaching for Equity (SHORE), Department of Surgery, University of Rochester Medical Center, Rochester, NY, United States
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Hardy SJ, Finkelstein A, Milano MT, Schifitto G, Sun H, Holley K, Usuki K, Weber MT, Zheng D, Seplaki CL, Janelsins M. Association of Radiation Dose to the Amygdala-Orbitofrontal Network with Emotion Recognition Task Performance in Patients with Low-Grade and Benign Brain Tumors. Cancers (Basel) 2023; 15:5544. [PMID: 38067248 PMCID: PMC10705220 DOI: 10.3390/cancers15235544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/16/2023] [Accepted: 11/18/2023] [Indexed: 02/12/2024] Open
Abstract
BACKGROUND Although data are limited, difficulty in social cognition occurs in up to 83% of patients with brain tumors. It is unknown whether cranial radiation therapy (RT) dose to the amygdala-orbitofrontal network can impact social cognition. METHODS We prospectively enrolled 51 patients with low-grade and benign brain tumors planned for cranial RT. We assessed longitudinal changes on an emotion recognition task (ERT) that measures the ability to recognize emotional states by displaying faces expressing six basic emotions and their association with the RT dose to the amygdala-orbitofrontal network. ERT outcomes included the median time to choose a response (ERTOMDRT) or correct response (ERTOMDCRT) and total correct responses (ERTHH). RESULTS The RT dose to the amygdala-orbitofrontal network was significantly associated with longer median response times on the ERT. Increases in median response times occurred at lower doses than decreases in total correct responses. The medial orbitofrontal cortex was the most important variable on regression trees predicting change in the ERTOMDCRT. DISCUSSION This is, to our knowledge, the first study to show that off-target RT dose to the amygdala-orbitofrontal network is associated with performance on a social cognition task, a facet of cognition that has previously not been mechanistically studied after cranial RT.
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Affiliation(s)
- Sara J. Hardy
- Department of Radiation Oncology, University of Rochester, Rochester, NY 14620, USA; (M.T.M.); (D.Z.); (M.J.)
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA;
| | - Alan Finkelstein
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA;
- Center for Advanced Brain Imaging and Neurophysiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Michael T. Milano
- Department of Radiation Oncology, University of Rochester, Rochester, NY 14620, USA; (M.T.M.); (D.Z.); (M.J.)
| | - Giovanni Schifitto
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA;
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY 14642, USA;
| | - Hongying Sun
- Department of Surgery, Supportive Care in Cancer, University of Rochester Medical Center, Rochester, NY 14642, USA; (H.S.); (M.T.W.)
| | - Koren Holley
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY 14642, USA;
| | - Kenneth Usuki
- Department of Radiation Oncology, University of Rochester, Rochester, NY 14620, USA; (M.T.M.); (D.Z.); (M.J.)
| | - Miriam T. Weber
- Department of Surgery, Supportive Care in Cancer, University of Rochester Medical Center, Rochester, NY 14642, USA; (H.S.); (M.T.W.)
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Dandan Zheng
- Department of Radiation Oncology, University of Rochester, Rochester, NY 14620, USA; (M.T.M.); (D.Z.); (M.J.)
| | - Christopher L. Seplaki
- Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY 14642, USA;
- Office for Aging Research and Health Services, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Michelle Janelsins
- Department of Radiation Oncology, University of Rochester, Rochester, NY 14620, USA; (M.T.M.); (D.Z.); (M.J.)
- Department of Surgery, Supportive Care in Cancer, University of Rochester Medical Center, Rochester, NY 14642, USA; (H.S.); (M.T.W.)
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Yoon J, Jung H, Tanny SM, Lemus OMD, Milano MT, Hardy SJ, Usuki KY, Zheng D. A comprehensive evaluation of advanced dose calculation algorithms for brain stereotactic radiosurgery. J Appl Clin Med Phys 2023; 24:e14169. [PMID: 37775989 PMCID: PMC10647955 DOI: 10.1002/acm2.14169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 09/01/2023] [Accepted: 09/18/2023] [Indexed: 10/01/2023] Open
Abstract
PURPOSE Accurate dose calculation is important in both target and low dose normal tissue regions for brain stereotactic radiosurgery (SRS). In this study, we aim to evaluate the dosimetric accuracy of the two advanced dose calculation algorithms for brain SRS. METHODS Retrospective clinical case study and phantom study were performed. For the clinical study, 138 SRS patient plans (443 targets) were generated using BrainLab Elements Voxel Monte Carlo (VMC). To evaluate the dose calculation accuracy, the plans were exported into Eclipse and recalculated with Acuros XB (AXB) algorithm with identical beam parameters. The calculated dose at the target center (Dref), dose to 95% target volume (D95), and the average dose to target (Dmean) were compared. Also, the distance from the skull was analyzed. For the phantom study, a cylindrical phantom and a head phantom were used, and the delivered dose was measured by an ion chamber and EBT3 film, respectively, at various locations. The measurement was compared with the calculated doses from VMC and AXB. RESULTS In clinical cases, VMC dose calculations tended to be higher than AXB. It was found that the difference in Dref showed > 5% in some cases for smaller volumes < 0.3 cm3 . Dmean and D95 differences were also higher for small targets. No obvious trend was found between the dose difference and the distance from the skull. In phantom studies, VMC dose was also higher than AXB for smaller targets, and VMC showed better agreement with the measurements than AXB for both point dose and high dose spread. CONCLUSION The two advanced calculation algorithms were extensively compared. For brain SRS, AXB sometimes calculates a noticeable lower target dose for small targets than VMC, and VMC tends to have a slightly closer agreement with measurements than AXB.
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Affiliation(s)
- Jihyung Yoon
- Department of Radiation OncologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - Hyunuk Jung
- Department of Radiation OncologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - Sean M. Tanny
- Department of Radiation OncologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - Olga Maria Dona Lemus
- Department of Radiation OncologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - Michael T. Milano
- Department of Radiation OncologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - Sara J. Hardy
- Department of Radiation OncologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - Kenneth Y. Usuki
- Department of Radiation OncologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
| | - Dandan Zheng
- Department of Radiation OncologyUniversity of Rochester Medical CenterRochesterNew YorkUSA
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Hardy SJ, Bandyopadhyay S, Yang H, Williams A, Gudina A, Cummings MA, Zhang H, Singh DP, Chen Y, Mohile NA, Janelsins MC, Milano MT. Stroke death in patients receiving radiation for head and neck cancer in the modern era. Front Oncol 2023; 13:1111764. [PMID: 37397363 PMCID: PMC10313411 DOI: 10.3389/fonc.2023.1111764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 05/30/2023] [Indexed: 07/04/2023] Open
Abstract
Objectives Head and neck cancer is a common malignancy frequently treated with chemotherapy and radiotherapy. Studies have shown an increased risk of stroke with the receipt of radiotherapy, but data on stroke-related mortality are limited, particularly in the modern era. Evaluating stroke mortality related to radiotherapy is vital given the curative nature of head and neck cancer treatment and the need to understand the risk of severe stroke in this population. Methods We analyzed the risk of stroke death among 122,362 patients (83,651 patients who received radiation and 38,711 patients who did not) with squamous cell carcinoma of the head and neck (HNSCC) diagnosed between 1973 and 2015 in the SEER database. Patients in radiation vs. no radiation groups were matched using propensity scores. Our primary hypothesis was that radiotherapy would increase the hazard of death from stroke. We also examined other factors impacting the hazard of stroke death, including whether radiotherapy was performed during the modern era when IMRT and modern stroke care were available as well as increased HPV-mediated cancers of the head and neck. We hypothesized that the hazard of stroke death would be less in the modern era. Results There was an increased hazard of stroke-related death in the group receiving radiation therapy (HR 1.203, p = 0.006); however, this was a very small absolute increase, and the cumulative incidence function of stroke death was significantly reduced in the modern era (p < 0.001), cohorts with chemotherapy (p=0.003), males (p=0.002), younger cohorts (p<0.001) and subsites other than nasopharynx (p=0.025). Conclusions While radiotherapy for head and neck cancer increases the hazard of stroke death, this is reduced in the modern era and remains a very small absolute risk.
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Affiliation(s)
- Sara J. Hardy
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, United States
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, United States
| | - Sanjukta Bandyopadhyay
- Department of Clinical and Translational Research, University of Rochester Medical Center, School of Medicine and Dentistry, Rochester, NY, United States
| | - Hongmei Yang
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, School of Medicine and Dentistry, Rochester, NY, United States
| | - Annalynn Williams
- Department of Surgery, Cancer Control, University of Rochester Medical Center School of Medicine and Dentistry, Rochester, NY, United States
- Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY, United States
| | - Abdi Gudina
- Department of Surgery, Cancer Control, University of Rochester Medical Center School of Medicine and Dentistry, Rochester, NY, United States
| | - Michael A. Cummings
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, United States
| | - Hong Zhang
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, United States
| | - Deepinder P. Singh
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, United States
| | - Yuhchyau Chen
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, United States
| | - Nimish A. Mohile
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, United States
| | - Michelle C. Janelsins
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, United States
- Department of Surgery, Cancer Control, University of Rochester Medical Center School of Medicine and Dentistry, Rochester, NY, United States
- Wilmot Cancer Center, University of Rochester Medical Center, Rochester, NY, United States
- Department of Neuroscience, University of Rochester Medical Center, School of Medicine and Dentistry, Rochester, NY, United States
| | - Michael T. Milano
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, United States
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Hardy SJ, Finkelstein AJ, Tivarus M, Culakova E, Mohile N, Weber M, Lin E, Zhong J, Usuki K, Schifitto G, Milano M, Janelsins-Benton MC. Cognitive and neuroimaging outcomes in individuals with benign and low-grade brain tumours receiving radiotherapy: a protocol for a prospective cohort study. BMJ Open 2023; 13:e066458. [PMID: 36792323 PMCID: PMC9933762 DOI: 10.1136/bmjopen-2022-066458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 01/27/2023] [Indexed: 02/17/2023] Open
Abstract
INTRODUCTION Radiation-induced cognitive decline (RICD) occurs in 50%-90% of adult patients 6 months post-treatment. In patients with low-grade and benign tumours with long expected survival, this is of paramount importance. Despite advances in radiation therapy (RT) treatment delivery, better understanding of structures important for RICD is necessary to improve cognitive outcomes. We hypothesise that RT may affect network topology and microstructural integrity on MRI prior to any gross anatomical or apparent cognitive changes. In this longitudinal cohort study, we aim to determine the effects of RT on brain structural and functional integrity and cognition. METHODS AND ANALYSIS This study will enroll patients with benign and low-grade brain tumours receiving partial brain radiotherapy. Patients will receive either hypofractionated (>2 Gy/fraction) or conventionally fractionated (1.8-2 Gy/fraction) RT. All participants will be followed for 12 months, with MRIs conducted pre-RT and 6-month and 12 month post-RT, along with a battery of neurocognitive tests and questionnaires. The study was initiated in late 2018 and will continue enrolling through 2024 with final follow-ups completing in 2025. The neurocognitive battery assesses visual and verbal memory, attention, executive function, processing speed and emotional cognition. MRI protocols incorporate diffusion tensor imaging and resting state fMRI to assess structural connectivity and functional connectivity, respectively. We will estimate the association between radiation dose, imaging metrics and cognitive outcomes. ETHICS AND DISSEMINATION This study has been approved by the Research Subjects Review Board at the University of Rochester (STUDY00001512: Cognitive changes in patients receiving partial brain radiation). All results will be published in peer-reviewed journals and at scientific conferences. TRIAL REGISTRATION NUMBER ClinicalTrials.gov NCT04390906.
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Affiliation(s)
- Sara J Hardy
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, New York, USA
- Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
| | - Alan J Finkelstein
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
- Center for Advanced Brain Imaging and Neurophysiology, University of Rochester Medical Center, Rochester, New York, USA
| | - Madalina Tivarus
- Center for Advanced Brain Imaging and Neurophysiology, University of Rochester Medical Center, Rochester, New York, USA
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Eva Culakova
- Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA
| | - Nimish Mohile
- Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
| | - Miriam Weber
- Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, New York, USA
| | - Edward Lin
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Jianhui Zhong
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
- Center for Advanced Brain Imaging and Neurophysiology, University of Rochester Medical Center, Rochester, New York, USA
| | - Kenneth Usuki
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, New York, USA
| | - Giovanni Schifitto
- Department of Neurology, Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Michael Milano
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, New York, USA
| | - M C Janelsins-Benton
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, New York, USA
- Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA
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Belcher EK, Culakova E, Gilmore NJ, Hardy SJ, Kleckner AS, Kleckner IR, Lei L, Heckler C, Sohn MB, Thompson BD, Lotta LT, Werner ZA, Geer J, Hopkins JO, Corso SW, Rich DQ, van Wijngaarden E, Janelsins MC. Inflammation, Attention, and Processing Speed in Patients With Breast Cancer Before and After Chemotherapy. J Natl Cancer Inst 2022; 114:712-721. [PMID: 35134984 PMCID: PMC9086766 DOI: 10.1093/jnci/djac022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 07/20/2021] [Accepted: 01/20/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Inflammation may contribute to cognitive difficulties in patients with breast cancer. We tested 2 hypotheses: inflammation is elevated in patients with breast cancer vs noncancer control participants and inflammation in patients is associated with worse attention and processing speed over the course of chemotherapy. METHODS Serum cytokines (interleukin [IL]-4, 6, 8, 10; tumor necrosis factor [TNF]-α) and soluble receptors [sTNFRI, II]) were measured in 519 females with breast cancer before and after chemotherapy and 338 females without cancer serving as control participants. Attention and processing speed were measured by Rapid Visual Processing (RVP), Backward Counting (BCT), and Trail Making-A (TMT-A) tests. Linear regression models examined patient vs control cytokines and receptor levels, adjusting for covariates. Linear regression models also examined relationships between patient cytokines and receptor levels and test performance, adjusting for age, body mass index, anxiety, depression, cognitive reserve, and chemotherapy duration. Statistical tests were 2-sided (α = .05). RESULTS sTNFRI and sTNFRII increased over time in patients relative to controls, whereas IL-4, IL-6, and IL-10 decreased. Prechemotherapy, higher IL-8 associated with worse BCT (β = 0.610, SE = 0.241, P = .01); higher IL-4 (β = -1.098, SE = 0.516, P = .03) and IL-10 (β = -0.835, SE = 0.414, P = .04) associated with better TMT-A. Postchemotherapy, higher IL-8 (β = 0.841, SE = 0.260, P = .001), sTNFRI (β = 6.638, SE = 2.208, P = .003), and sTNFRII (β = 0.913, SE = 0.455, P = .045) associated with worse BCT; higher sTNFRII also associated with worse RVP (β = -1.316, SE = 0.587, P = .03). At prechemotherapy, higher IL-4 predicted RVP improvement over time (β = 0.820, SE = 0.336, P = .02); higher sTNFRI predicted worse BCT over time (β = 5.566, SE = 2.367, P = .02). Longitudinally, increases in IL-4 associated with BCT improvement (β = -0.564, SE = 0.253, P = .03). CONCLUSIONS Generally, worse attention and processing speed were associated with higher inflammatory cytokines and receptors and lower anti-inflammatory cytokines in patients; future confirmatory studies are needed.
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Affiliation(s)
- Elizabeth K Belcher
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Eva Culakova
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Nikesha J Gilmore
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Sara J Hardy
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA,Department of Radiation Oncology and Neurology, University of Rochester Medical Center, Rochester, NY, USA
| | - Amber S Kleckner
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Ian R Kleckner
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Lianlian Lei
- Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Charles Heckler
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Michael B Sohn
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, USA
| | - Bryan D Thompson
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Louis T Lotta
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Zachary A Werner
- Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, Rochester, NY, USA
| | - Jodi Geer
- Metro Minnesota Community Oncology Research Consortium, Louis Park, MN, USA
| | | | - Steven W Corso
- Upstate Carolina National Cancer Institute Community Oncology Research Program, Spartanburg Regional Medical Center, Spartanburg, SC, USA
| | - David Q Rich
- Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY, USA
| | - Edwin van Wijngaarden
- Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY, USA
| | - Michelle C Janelsins
- Correspondence to: Michelle Janelsins, PhD, MPH, Department of Surgery, Supportive Care in Cancer Division, University of Rochester Medical Center, 265 Crittenden Blvd, Box 658, Rochester, NY 14642, USA (e-mail: )
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Chowdhry AK, Hardy SJ, Milano MT. Nivolumab without brain radiotherapy is insufficient for the treatment of most patients with brain metastases from clear cell renal cell carcinoma. Ann Transl Med 2019; 7:S366. [PMID: 32016084 DOI: 10.21037/atm.2019.09.10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Amit K Chowdhry
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, USA
| | - Sara J Hardy
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, USA
| | - Michael T Milano
- Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY, USA
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Abstract
Advances in cancer treatments have led to substantially improved survival for patients with cancer. However, many patients experience changes in cognition as a side effect of both cancer and cancer treatment. This occurs with both central nervous system (CNS) tumors and non-CNS tumors and in both children and adults. Studies of patients with non-CNS cancer have shown that cancer-related cognitive impairment (CRCI), which can include changes in memory, executive function, attention, and processing speed, occurs in up to 30% of patients prior to any treatment and in up to 75% of patients during treatment. A subset of patients with non-CNS and CNS cancer appear to be at higher risk for CRCI, so much research has gone into identifying who is vulnerable. Risk factors for CRCI in adults include cognitive reserve, age, genetic factors, and ethnicity; risk factors for children include genetic factors, female sex, younger age at diagnosis, chemotherapy dose, and both dose and field size for radiation. Although the field has made substantial strides in understanding and treating CRCI, more research is still needed to improve outcomes for both pediatric and adult cancer survivors.
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Affiliation(s)
- Sara J Hardy
- From the University of Rochester Medical Center, Rochester, NY; St. Jude Children's Research Hospital, Memphis, TN; The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Kevin R Krull
- From the University of Rochester Medical Center, Rochester, NY; St. Jude Children's Research Hospital, Memphis, TN; The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Jeffrey S Wefel
- From the University of Rochester Medical Center, Rochester, NY; St. Jude Children's Research Hospital, Memphis, TN; The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Michelle Janelsins
- From the University of Rochester Medical Center, Rochester, NY; St. Jude Children's Research Hospital, Memphis, TN; The University of Texas MD Anderson Cancer Center, Houston, TX
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Affiliation(s)
- Sara J Hardy
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - David R Benavides
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kiran T Thakur
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - John C Probasco
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Carlos A Pardo
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Hardy SJ, Nowacki AS, Bertin M, Weil RJ. Absence of an association between glucose levels and surgical site infections in patients undergoing craniotomies for brain tumors. J Neurosurg 2010; 113:161-6. [DOI: 10.3171/2010.2.jns09950] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
In select patient populations, hyperglycemia has been shown to increase the risk of surgical site infection (SSI), whereas stringent glucose control has improved outcomes. To date, no study has focused on whether SSIs in patients with brain tumors undergoing resection are associated with hyperglycemia.
Methods
The authors performed a retrospective chart review of patients who underwent a craniotomy after receiving a diagnosis of brain tumor. From 2001 to 2008, 2485 patients underwent a craniotomy for tumor resection at the Brain Tumor & Neuro-Oncology Center at the Cleveland Clinic. Fifty-seven of these patients (2.3%) developed SSIs postoperatively. A matched case-control study design was used, with 57 patients who developed SSIs after craniotomy (cases) matched with 57 patients who did not develop SSIs (controls). The results were analyzed using both univariate and multivariate conditional logistic regression.
Results
Glucose level was not a significant factor in postoperative SSI (p = 0.83) after adjusting for duration of surgery and adherence to antibiotic prophylaxis. However, duration of surgery was significantly associated with postoperative SSI (p = 0.047).
Conclusions
For patients who undergo craniotomy for definitive resection of a brain tumor, duration of surgery described more variation in the model to predict SSI than blood glucose levels.
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Affiliation(s)
- Sara J. Hardy
- 1The Brain Tumor & Neuro-Oncology Center, Department of Neurosurgery, the Neurological Institute; and Departments of
| | | | - Mary Bertin
- 3Quality/Infection Control, Cleveland Clinic, Cleveland, Ohio
| | - Robert J. Weil
- 1The Brain Tumor & Neuro-Oncology Center, Department of Neurosurgery, the Neurological Institute; and Departments of
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11
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Topping TB, Woodbury RL, Diamond DL, Hardy SJ, Randall LL. Direct demonstration that homotetrameric chaperone SecB undergoes a dynamic dimer-tetramer equilibrium. J Biol Chem 2001; 276:7437-41. [PMID: 11110800 DOI: 10.1074/jbc.m009584200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown here that the cytosolic bacterial chaperone SecB is a structural dimer of dimers that undergoes a dynamic equilibrium between dimer and tetramer in the native state. We demonstrated this equilibrium by mixing two tetrameric species of SecB that can be distinguished by size. We showed that the homotetrameric species exchanged dimers, because when the mixture was analyzed both by size exclusion chromatography and native polyacrylamide gel electrophoresis a third hybrid tetrameric species was detected. Furthermore, treatment of SecB with 5,5'-dithiobis-(2-nitrobenzoic acid), which modifies the sulfhydryl group on cysteines, caused irreversible dissociation to a dimer indicating that cysteine must be involved in the stabilizing interactions at the dimer interface. It is clear that the two dimer-dimer interfaces of the SecB tetramer are differentially stable. Dissociation at one interface allows for a dynamic dimer-tetramer equilibrium. Because only dimers were exchanged it is clear that the other interface between dimers is significantly more stable, otherwise oligomers should have formed with a random distribution of monomers.
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Affiliation(s)
- T B Topping
- School of Molecular Biosciences, Washington State University, Pullman 99164-4660, USA.
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12
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Affiliation(s)
- L L Randall
- Department of Biochemistry, University of Missouri-Columbia, 65211, USA
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13
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Humpage AR, Hardy SJ, Moore EJ, Froscio SM, Falconer IR. Microcystins (cyanobacterial toxins) in drinking water enhance the growth of aberrant crypt foci in the mouse colon. J Toxicol Environ Health A 2000; 61:155-165. [PMID: 11036504 DOI: 10.1080/00984100050131305] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Microcystis aeruginosa produces toxic cyclic peptides called microcystins, potent hepatotoxins that have been implicated in tumor promotion in skin and liver. The model used in this investigation was the azoxymethane (AOM)-induced aberrant crypt focus (ACF) in the male C57Bl/6J mouse colon. Three intraperitoneal (i.p.) injections of 5 mg/kg AOM were administered at 7-d intervals to mice; 19 d after the last AOM injection, drinking water containing Microcystis extract was commenced and continued for a further 212 d. The content of microcystins in the drinking water was determined by mouse bioassay, high-performance liquid chromatography (HPLC), capillary eletrophoresis, and protein phosphatase inhibition. The doses employed were 0, 382, and 693 micrograms/kg bodyweight/d at the midpoint of the trial. Following postmortem examination blood cells, serum enzymes and organ pathology were investigated. A significant microcystin dose-dependent increase in the area of aberrant crypt foci was observed. There was no marked increase in the number of crypts/colon. Two overt colonic tumors (approximately 30 mm3) were seen in microcystin-treated mice, and one microscopic colonic tumor in an AOM-alone-treated mouse. This investigation provides the first evidence for the stimulation of preneoplastic colon tumor growth by microcystin.
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Affiliation(s)
- A R Humpage
- Department of Clinical and Experimental Pharmacology, University of Adelaide, Australia
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14
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Woodbury RL, Topping TB, Diamond DL, Suciu D, Kumamoto CA, Hardy SJ, Randall LL. Complexes between protein export chaperone SecB and SecA. Evidence for separate sites on SecA providing binding energy and regulatory interactions. J Biol Chem 2000; 275:24191-8. [PMID: 10807917 DOI: 10.1074/jbc.m002885200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During localization to the periplasmic space or to the outer membrane of Escherichia coli some proteins are dependent on binding to the cytosolic chaperone SecB, which in turn is targeted to the membrane by specific interaction with SecA, a peripheral component of the translocase. Five variant forms of SecB, previously demonstrated to be defective in mediating export in vivo (Gannon, P. M., and Kumamoto, C. A. (1993) J. Biol. Chem. 268, 1590-1595; Kimsey, H. K., Dagarag, M. D., and Kumamoto, C. A. (1995) J. Biol. Chem. 270, 22831-22835) were investigated with respect to their ability to bind SecA both in solution and at the membrane translocase. We present evidence that at least two regions of SecA are involved in the formation of active complexes with SecB. The variant forms of SecB were all capable of interacting with SecA in solution to form complexes with stability similar to that of complexes between SecA and wild-type SecB. However, the variant forms were defective in interaction with a separate region of SecA, which was shown to trigger a change that was correlated to activation of the complex. The region of SecA involved in activation of the complexes was defined as the extreme carboxyl-terminal 21 aminoacyl residues.
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Affiliation(s)
- R L Woodbury
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660, USA
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15
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Abstract
The interaction of Neisseria meningitidis with the meninges that surround and protect the brain is a pivotal event in the progression of bacterial meningitis. Two models of the human meninges were established in vitro, using (i) sections of fresh human brain and (ii) cultures of viable cells grown from human meningiomas. Neisseria meningitidis showed a specific predilection for binding to the leptomeninges and meningeal blood vessels in human brain and not to the cerebral cortex. There was a close correlation between the adherence of different Neisseria species to leptomeninges and cultured cells. The major ligand that mediated adherence was the pilus, and pilin variation modulated the interactions. The presence of Opa protein increased the association of Cap+ meningococci that expressed low-adhesive pili, but did not influence the association of high-adhesive pili. In contrast, Opc did not influence the adherence of Cap+ meningococci, whereas loss of capsule was associated with a more intimate interaction between the bacteria and the meningioma cell that was not apparent with Cap+ meningococci. There was no evidence of internalization of meningococci by meningioma cells in vitro, an observation that is consistent with the barrier properties of the leptomeninges to N. meningitidis observed in vivo.
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Affiliation(s)
- S J Hardy
- Department of Microbiology and Pathology, Division of Cell and Molecular Medicine, University of Southampton Medical School, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, UK
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16
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Randall LL, Hardy SJ, Topping TB, Smith VF, Bruce JE, Smith RD. The interaction between the chaperone SecB and its ligands: evidence for multiple subsites for binding. Protein Sci 1998; 7:2384-90. [PMID: 9828004 PMCID: PMC2143860 DOI: 10.1002/pro.5560071115] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The chaperone protein SecB is dedicated to the facilitation of export of proteins from the cytoplasm to the periplasm and outer membrane of Escherichia coli. It functions to bind and deliver precursors of exported proteins to the membrane-associated translocation apparatus before the precursors fold into their native stable structures. The binding to SecB is characterized by a high selectivity for ligands having nonnative structure but a low specificity for consensus in sequence among the ligands. A model previously presented (Randall LL, Hardy SJS, 1995, Trends Biochem Sci 20:65-69) to rationalize the ability of SecB to distinguish between the native and nonnative states of a polypeptide proposes that the SecB tetramer contains two types of subsites for ligand binding: one kind that would interact with extended flexible stretches of polypeptides and the other with hydrophobic regions. Here we have used titration calorimetry, analytical ultracentrifugation, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry to obtain evidence that such distinguishable subsites exist.
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Affiliation(s)
- L L Randall
- Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-4660, USA
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17
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Abstract
SecB is a chaperone in Escherichia coli dedicated to export of proteins from the cytoplasm to the periplasm and outer membrane. It functions to bind and deliver precursors of exported proteins to the translocation apparatus before they fold into their native structures, thus maintaining them in a competent state for translocation across the membrane. The natural ligands of SecB are precursor proteins containing leader sequences. There are numerous reports in the literature indicating that SecB does not specifically recognize the leader peptides. However, two published investigations have concluded that the leader peptide is the recognition element (Watanabe M, Blobel G. 1989. Cell 58:685-705; Watanabe M, Blobel G. 1995. Proc Natl Acad Sci USA 92:10133-10136). In this work we use titration calorimetry to show that SecB binds two physiological ligands, which contain leader sequences, with no higher affinity than the same molecules lacking their leader sequences. Indeed, for one ligand the presence of the leader sequence reduces the affinity. Therefore, it can be concluded that the leader sequence provides no positive contribution to the binding energy.
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Affiliation(s)
- L L Randall
- Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-4660, USA
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Affiliation(s)
- L L Randall
- Department of Biochemistry, Washington State University, Pullman 99164-4660, USA
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19
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Abstract
Chaperone proteins demonstrate the paradoxical ability to bind ligands rapidly and with high affinity but with no apparent sequence specificity. To learn more about this singular property, we have mapped the binding frame of the chaperone SecB from E. coli on the oligopeptide-binding protein. Similar studies performed on the maltose-binding and galactose-binding proteins revealed centrally positioned binding frames of approximately 160 aminoacyl residues. The work described here shows that OppA, which is significantly longer than the previously studied ligands, has a binding frame that covers 460 amino acids, nearly the entire length of the protein. We propose modes of binding to account for the data.
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Affiliation(s)
- V F Smith
- Department of Biochemistry and Biophysics, Washinton State University, Pullman 99164-4660, USA
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20
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Randall LL, Topping TB, Hardy SJ, Pavlov MY, Freistroffer DV, Ehrenberg M. Binding of SecB to ribosome-bound polypeptides has the same characteristics as binding to full-length, denatured proteins. Proc Natl Acad Sci U S A 1997; 94:802-7. [PMID: 9023337 PMCID: PMC19594 DOI: 10.1073/pnas.94.3.802] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The interaction of the chaperone SecB with ribosome-bound polypeptides that are in the process of elongation has been studied using an in vitro protein synthesis system. The binding is characterized by the same properties as those demonstrated for the binding of SecB to full-length proteins that are in nonnative conformation: it is readily reversible and has no specificity for the leader peptide. In addition, it is shown that the growing polypeptide chains must achieve a critical length to bind tightly enough to allow their isolation in complex with SecB. This explains the longstanding observation that, even when export is cotranslational, it begins late in synthesis. Furthermore, the required length is approximately the same as the length that defines the binding frame within denatured, full-length proteins bound to SecB.
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Affiliation(s)
- L L Randall
- Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-4660, USA
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Abstract
The B subunit of heat-labile enterotoxin, a periplasmic protein of Escherichia coli has an internal disulfide bond that forms after the protein has been exported. The presence of 2.5 mM dithiothreitol in the medium prevents the formation of the disulfide bond and this causes the protein to rapidly bind to membranes, preferentially but not exclusively to the cytoplasmic membrane. The binding is irreversible in vivo but chaotropic agents disrupt the association between the non-native B subunit and the membranes in vitro. The fact that the reduced B subunit binds to both the cytoplasmic and outer membranes that enclose the periplasm suggests that it is exported normally to the periplasm and then, because it is unable to form its native structure, adsorbs to membranes in the vicinity. This is confirmed by the finding that when synthesised by spheroplasts, in which the outer membrane is disrupted, the majority of reduced B subunit, which is not now confined in the periplasm, is exported to the medium and is not associated with membranes.
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Affiliation(s)
- S J Hardy
- Department of Biology, University of York, UK
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23
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Abstract
One of the two cysteines in the B subunit of heat-labile enterotoxin has been changed to a serine by site-directed mutagenesis so that the internal disulfide bond cannot form. The mutant protein, like the wild-type protein synthesised in the presence of the reducing agent dithiothreitol, does not form pentamers in the periplasm but binds to available membranes. Binding to membranes is disrupted by chaotropic agents but not by salt. More than half the molecules of mutant protein form disulfide-bonded dimers when exported to the periplasm but no dimer is detected when the protein is exported to the medium by spheroplasts.
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Affiliation(s)
- P A Hedges
- Department of Biology, University of York, UK
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24
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Hardy SJ, Robinson BS, Ferrante A, Hii CS, Johnson DW, Poulos A, Murray AW. Polyenoic very-long-chain fatty acids mobilize intracellular calcium from a thapsigargin-insensitive pool in human neutrophils. The relationship between Ca2+ mobilization and superoxide production induced by long- and very-long-chain fatty acids. Biochem J 1995; 311 ( Pt 2):689-97. [PMID: 7487914 PMCID: PMC1136054 DOI: 10.1042/bj3110689] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Fatty acids with more than 22 carbon atoms (very-long-chain fatty acids; VLCFAs) are normal cellular components that have been implicated in the pathophysiology of a number of peroxisomal disorders. To date, however, essentially nothing is known regarding their biological activities. Ca2+ mobilization is an important intracellular signalling system for a variety of agonists and cell types. Given that several polyunsaturated long-chain fatty acids mobilize intracellular Ca2+ and that we have postulated that the VLCFAs may be involved in signal transduction, we examined whether the tetraenoic VLCFA induced Ca2+ mobilization in human neutrophils. We report that fatty acid-induced intracellular Ca2+ mobilization declined for fatty acid species of more than 20 carbon atoms, but increased again as the carbon chain length approached 30. This Ca2+ mobilization occurred independently of inositol 1,4,5-triphosphate production and protein kinase C translocation and involved both the release of Ca2+ from the intracellular stores and changes to the influx or efflux of the ion. We further observed that triacontatetraenoic acid [30:4(n-6)] mobilized Ca2+ from a thapsigargin-insensitive intracellular pool distinct from the thapsigargin-sensitive pools affected by arachidonic acid [20:4(n - 6)] or N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). 20:4 (n - 6) induced strong superoxide production (chemiluminescence) which was inhibited by thapsigargin pretreatment. In contrast, fatty acid-induced superoxide production progressively declined as the carbon chain length increased beyond 20-22 carbon atoms. Further studies suggested that the thapsigargin-insensitive Ca2+ mobilization elicited by 30:4 (n - 6) was not related to oxyradical formation, while the thapsigargin-sensitive Ca2+ mobilization induced by 20:4 (n - 6) may be involved in the initiation but not necessarily the maintenance of superoxide production. In conclusion, this is the first report to demonstrate a biological activity for the VLCFA and indicates that 30:4 (n - 6) influences second messenger systems in intact cells that differ from those affected by long-chain fatty acids such as 20:4 (n - 6).
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Affiliation(s)
- S J Hardy
- Department of Immunology, Women's and Children's Hospital, North Adelaide, Australia
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Hardy SJ, Agostini DE. Accidental epinephrine auto-injector-induced digital ischemia reversed by phentolamine digital block. J Am Osteopath Assoc 1995; 95:377-8. [PMID: 7615410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The use of epinephrine-containing auto-injectors as a prescription medication for treating routine to severe anaphylactic reactions is now widely accepted. Associated with this trend is an increasing number of accidental injections of epinephrine into digits, causing severe vasoconstriction and the risk of ischemic necrosis. When epinephrine is accidentally discharged into a digit, ischemic skin necrosis resulting from the alpha-adrenergic blocking effects of this agent can lead to the need for multiple operations, wound infection, and even loss of the digit. The alpha-adrenergic blocking characteristics of phentolamine administered by a variety of methods have proved effective in reversing the effects of epinephrine in these cases. The authors urge that the described treatment protocol become more widely disseminated among primary care and emergency physicians.
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Affiliation(s)
- S J Hardy
- Millcreek Community Hospital, Emergency Medical Department, Erie, PA 16509-2603, USA
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26
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Abstract
Fundamental to the function of all molecular chaperones is their amazing ability to selectively and rapidly bind proteins in non-native states. Chaperones modulate a kinetic partitioning among the alternative pathways open to polypeptides within a cell, so that the proper pathway is taken. Here we review studies of SecB, a chaperone in Escherichia coli dedicated to facilitation of protein export, and emphasize the features that enable it to bind rapidly with high affinity and selectivity in the absence of consensus in sequence. The concepts discussed are likely to be generally applicable to chaperones.
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Affiliation(s)
- L L Randall
- Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-4660
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27
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Hardy SJ, Ferrante A, Poulos A, Robinson BS, Johnson DW, Murray AW. Effect of exogenous fatty acids with greater than 22 carbon atoms (very long chain fatty acids) on superoxide production by human neutrophils. The Journal of Immunology 1994. [DOI: 10.4049/jimmunol.153.4.1754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The effects of exogenous long chain fatty acids (LCFA) and very long chain fatty acids (VLCFA) on superoxide production by human neutrophils were compared. Superoxide production was greater and more rapid in response to arachidonic (20:4 (n-6)), eicosapentanoic (20:5 (n-3)), and docosahexanoic (22:6 (n-3)) acids than for triacontatetranoic (30:4 (n-6)), dotriacontatetranoic (32:4 (n-6)), and tetratriacontahexanoic (34:6 (n-3)) acids, although all of these fatty acids gave responses larger than FMLP. A similar decline in activity with increasing carbon chain length was observed for the monoenoic VLCFA (22:1 (n-9) to 34:1 (n-9)). 32:4 (n-6) did not affect responses to a maximally stimulatory concentration of 20:4 (n-6). However, the simultaneous addition of 20:4 (n-6) and 30:4 (n-6) gave additive responses if suboptimal dosages of 20:4 (n-6) were used. This suggests that the LCFA and VLCFA may use the same signal transduction systems. In addition, 30:4 (n-6) was only 10% as effective as was 20:4 (n-6) at gaining access to the organic solvent extractable cellular fraction. This figure correlated with the relative biologic potency of 20:4 (n-6) and 30:4 (n-6), suggesting that the extent of association with the cell may regulate the biologic activity of the fatty acids. The saturates, arachidic (20:0) and cerotic (26:0) acids, were either inactive or poor activators in all assay systems examined. The failure of 20:0 to induce superoxide production and the lower responses to 30:4 (n-6) and 34:6 (n-3) were not because of extracellular Ca2+, because the biologic potency of these fatty acids was not greatly enhanced by removing Ca2+ from the extracellular medium. In contrast, 20:4 (n-6)- and 22:6 (n-3)-induced superoxide production was markedly increased under Ca(2+)-free conditions.
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Affiliation(s)
- S J Hardy
- Department of Immunology, Women's and Children's Hospital, North Adelaide, South Australia
| | - A Ferrante
- Department of Immunology, Women's and Children's Hospital, North Adelaide, South Australia
| | - A Poulos
- Department of Immunology, Women's and Children's Hospital, North Adelaide, South Australia
| | - B S Robinson
- Department of Immunology, Women's and Children's Hospital, North Adelaide, South Australia
| | - D W Johnson
- Department of Immunology, Women's and Children's Hospital, North Adelaide, South Australia
| | - A W Murray
- Department of Immunology, Women's and Children's Hospital, North Adelaide, South Australia
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Hardy SJ, Ferrante A, Poulos A, Robinson BS, Johnson DW, Murray AW. Effect of exogenous fatty acids with greater than 22 carbon atoms (very long chain fatty acids) on superoxide production by human neutrophils. J Immunol 1994; 153:1754-61. [PMID: 8046242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effects of exogenous long chain fatty acids (LCFA) and very long chain fatty acids (VLCFA) on superoxide production by human neutrophils were compared. Superoxide production was greater and more rapid in response to arachidonic (20:4 (n-6)), eicosapentanoic (20:5 (n-3)), and docosahexanoic (22:6 (n-3)) acids than for triacontatetranoic (30:4 (n-6)), dotriacontatetranoic (32:4 (n-6)), and tetratriacontahexanoic (34:6 (n-3)) acids, although all of these fatty acids gave responses larger than FMLP. A similar decline in activity with increasing carbon chain length was observed for the monoenoic VLCFA (22:1 (n-9) to 34:1 (n-9)). 32:4 (n-6) did not affect responses to a maximally stimulatory concentration of 20:4 (n-6). However, the simultaneous addition of 20:4 (n-6) and 30:4 (n-6) gave additive responses if suboptimal dosages of 20:4 (n-6) were used. This suggests that the LCFA and VLCFA may use the same signal transduction systems. In addition, 30:4 (n-6) was only 10% as effective as was 20:4 (n-6) at gaining access to the organic solvent extractable cellular fraction. This figure correlated with the relative biologic potency of 20:4 (n-6) and 30:4 (n-6), suggesting that the extent of association with the cell may regulate the biologic activity of the fatty acids. The saturates, arachidic (20:0) and cerotic (26:0) acids, were either inactive or poor activators in all assay systems examined. The failure of 20:0 to induce superoxide production and the lower responses to 30:4 (n-6) and 34:6 (n-3) were not because of extracellular Ca2+, because the biologic potency of these fatty acids was not greatly enhanced by removing Ca2+ from the extracellular medium. In contrast, 20:4 (n-6)- and 22:6 (n-3)-induced superoxide production was markedly increased under Ca(2+)-free conditions.
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Affiliation(s)
- S J Hardy
- Department of Immunology, Women's and Children's Hospital, North Adelaide, South Australia
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29
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Hardy SJ, Ferrante A, Robinson BS, Johnson DW, Poulos A, Clark KJ, Murray AW. In vitro activation of rat brain protein kinase C by polyenoic very-long-chain fatty acids. J Neurochem 1994; 62:1546-51. [PMID: 8133282 DOI: 10.1046/j.1471-4159.1994.62041546.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A variety of fatty acids including the cis-polyunsaturated very-long-chain fatty acids (VLCFA) (> 22 carbon atoms) common in retina, spermatozoa, and brain were examined for their ability to activate protein kinase C (PKC) purified from rat brain. Arachidonic [20:4(n-6)], eicosapentaenoic [20:5(n-3)], and docosahexaenoic [22:6(n-3)] acids as well as the VLCFA dotriacontatetraenoic [32:4(n-6)] and tetratriacontahexaenoic [34:6(n-3)] were equally capable of activating PKC in vitro with maximal activity being between 25 and 50 microM. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate further enhanced the in vitro activation of PKC when added to the protein kinase assay system with the fatty acids. The fully saturated arachidic acid (20:0) was inactive in both assay systems. The potential significance of the in vitro activation of PKC by the VLCFA is discussed.
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Affiliation(s)
- S J Hardy
- Department of Immunology and University of Adelaide, Australia
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30
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Ferrante A, Goh D, Harvey DP, Robinson BS, Hii CS, Bates EJ, Hardy SJ, Johnson DW, Poulos A. Neutrophil migration inhibitory properties of polyunsaturated fatty acids. The role of fatty acid structure, metabolism, and possible second messenger systems. J Clin Invest 1994; 93:1063-70. [PMID: 8132744 PMCID: PMC294038 DOI: 10.1172/jci117056] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The n-3 polyunsaturated fatty acids (PUFA) appear to have antiinflammatory properties that can be partly explained by their biological activity on leukocytes. Since leukocyte emigration is an essential component of the inflammatory response, we have examined the effects of the n-3 PUFA (eicosapentaenoic and docosahexaenoic acids) on neutrophil random and chemotactic movement. Preexposure of neutrophils for 15-30 min to 1-10 micrograms/ml PUFA reduced the random and chemotactic migration to both FMLP- and fungi-activated complement. The inhibitory effect diminished with increasing saturation and carbon chain length, and methylation abolished this activity. Arachidonic and docosahexaenoic acids were the most active fatty acids. The PUFA concentration required to inhibit migration was dependent on cell number, suggesting that the fatty acid effects on leukocyte migration in vivo may be governed by the stage of the inflammatory response. It was concluded that the PUFA rather than their metabolites were responsible for the inhibition since: (a) antioxidants did not prevent the PUFA-induced migration inhibition and the hydroxylated intermediates were less active, and (b) inhibitors of the cyclooxygenase and lipoxygenase pathways were without effect. Inhibitors of protein kinases and calmodulin-dependent enzyme system did not prevent the PUFA-induced migration inhibition, which was also independent of phospholipase D-catalyzed hydrolysis of phospholipids. It is also shown that PUFA decrease the FMLP-induced Ca2+ mobilization.
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Affiliation(s)
- A Ferrante
- Department of Immunology, Women's and Children's Hospital, North Adelaide, South Australia
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31
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Hardy SJ, Randall LL. Recognition of ligands by SecB, a molecular chaperone involved in bacterial protein export. Philos Trans R Soc Lond B Biol Sci 1993; 339:343-52; discussion 352-4. [PMID: 8098539 DOI: 10.1098/rstb.1993.0033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
SecB is a molecular chaperone involved in protein export from Escherichia coli. It is a highly negatively charged, soluble, tetrameric protein with a monomer molecular mass of 16,400 kDa. It has two functions: it maintains precursors of some exported proteins in a conformation compatible with export, by preventing them from aggregating or from folding into their thermodynamically stable state in the cytoplasm, and it delivers both nascent and completed precursors to SecA, one of the components of the export apparatus that are on and in the plasma membrane. SecB recognizes completed precursors of soluble proteins, not by direct interaction with leader sequences but by virtue of the property, imposed by their leader sequences, that they fold slowly: i.e. there is a kinetic partitioning between folding and interaction with SecB. Only those polypeptides that fold slowly interact significantly with this molecular chaperone even though it is able to bind a wide variety of non-native proteins. Binding studies with purified peptides indicate that each SecB monomer has a binding site that can interact with flexible peptides having a net positive charge and a length of about ten residues, which may depend on the charge density. Binding of the hydrophobic fluorescent probe 1-anilino-naphthalene-8-sulphonate (ANS) indicates that simultaneous interaction of multiple peptides causes a conformational change that exposes a hydrophobic site on SecB. This hydrophobic region is thought to contribute an extra binding site for physiological ligands of SecB. A model of SecB binding to nonnative precursors is presented.
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Affiliation(s)
- S J Hardy
- Department of Biology, University of York, U.K
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Hardy SJ, Haylock DN, Lopez AF, Murray AW. Examination of the role of the proteolytically-activated form of protein kinase C in the differentiation of human haemopoietic cells. Differentiation 1992; 50:189-202. [PMID: 1426703 DOI: 10.1111/j.1432-0436.1992.tb00673.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In neutrophils, the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) induced the translocation of the Ca(++)- and phospholipid-dependent protein kinase, protein kinase C (PK-C) from the soluble to the particulate fraction. At the same time there was a corresponding increase in the amount of Ca(++)- and phospholipid-independent protein kinase activity recovered in the soluble fraction. This soluble Ca(++)- and phospholipid-independent protein kinase presumably reflects proteolytic activation of the particulate associated PK-C. Bone marrow and undifferentiated HL-60 cells also translocated PK-C to the particulate fraction in response to TPA but did not accumulate the soluble Ca(++)- and phospholipid-independent form of the enzyme. Similar results were obtained using HL-60 cells induced to differentiate with dimethyl sulphoxide (DMSO), recombinant human granulocyte-macrophage colony-stimulating factor (rh GM-CSF) or 1 alpha,25-dihydroxyvitamin D3. There was also no significant change in either the number or time of expression of differentiation-specific cell surface antigens observed on HL-60 cells induced to differentiate with either DMSO, 1 alpha,25-dihydroxyvitamin D3 or TPA in the presence of cyclosporin A, an agent reported to inhibit the proteolytic breakdown of PK-C to the Ca(++)- and phospholipid-independent form. Likewise, cyclosporin A did not affect the rate of extent of differentiation of primary bone marrow cell cultures. These results suggest that the proteolytically activated and phospholipid-independent form of PK-C is probably not involved in haemopoietic cell differentiation.
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Affiliation(s)
- S J Hardy
- School of Biological Sciences, Flinders University of South Australia, Adelaide
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Hardy SJ, Randall LL. Protein folding in protein export. Antonie Van Leeuwenhoek 1992; 61:101-3. [PMID: 1580610 DOI: 10.1007/bf00580614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- S J Hardy
- Department of Biology, University of York, Heslington, UK
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Hardy SJ, Robinson BS, Poulos A, Harvey DP, Ferrante A, Murray AW. The neutrophil respiratory burst. Responses to fatty acids, N-formylmethionylleucylphenylalanine and phorbol ester suggest divergent signalling mechanisms. Eur J Biochem 1991; 198:801-6. [PMID: 1646722 DOI: 10.1111/j.1432-1033.1991.tb16084.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The oxygen-dependent respiratory burst is a key neutrophil function required for the killing of bacteria. However, despite intensive investigation, the molecular events which initiate the respiratory burst remain unclear. Recent reports have suggested the agonist-induced hydrolysis of cellular phosphatidylcholine (PtdCho) by phospholipase D may be an essential requirement for initiating or mediating the respiratory burst. We have investigated the effects of the chemotactic peptide N-formylmethionylleucylphenylalanine (fMLF), the phorbol ester 12-O-tetradecanoyl-phorbol 13-acetate (TPA) and the polyunsaturated fatty acids arachidonic [20:4 (n-6)] and docosahexaenoic [22:6 (n-3)] acids in light of this hypothesis. Ethanol-inhibited superoxide production in response to 20:4, 22:6 and fMLF, in a dose-dependent fashion, suggesting an involvement of phospholipase D. The phosphatidic-acid phosphohydrolase inhibitor DL-propranolol completely inhibited superoxide production induced by both 20:4 and 22:6, and partially inhibited the response to TPA. In contrast, superoxide production in response to fMLF was increased by propranolol. fMLF and TPA, but not the fatty acids, stimulated phospholipase D as indicated by the accumulation of phosphatidic acid and, in the presence of ethanol, phosphatidylethanol derived from PtdCho. Extracellular Ca2+ was found to be an essential requirement for fMLF-induced superoxide production. However, responses to the fatty acids were dramatically enhanced under Ca(2+)-free conditions. Responses to TPA were independent of the extracellular Ca2+ concentration. Both fatty acids and fMLF, but not TPA, mobilised Ca2+ from intracellular stores, a response insensitive to the effects of both ethanol and propranolol. These results show that, unlike fMLF and TPA, the fatty acids do not cause hydrolysis of PtdCho by phospholipase D. However, the data indirectly suggests that the fatty acids may initiate the phospholipase-D-catalysed hydrolysis of phospholipids other than PtdCho.
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Affiliation(s)
- S J Hardy
- School of Biological Sciences, Flinders University of South Australia, Adelaide
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Abstract
An in vitro assay for the interaction of SecB, a molecular chaperone from Escherichia coli, with polypeptide ligands was established based on the ability of SecB to block the refolding of denatured maltose-binding protein. Competition experiments show that SecB binds selectively to nonnative proteins with high affinity and without specificity for a particular sequence of amino acids. It is proposed that selectivity in binding is due to a kinetic partitioning of polypeptides between folding and association with SecB.
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Affiliation(s)
- S J Hardy
- Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-4660
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Abstract
Most proteins destined for export from Escherichia coli are made as precursors containing amino-terminal leader sequences that are essential for export and that are removed during the process. The initial step in export of a subset of proteins, which includes maltose-binding protein, is binding of the precursor by the molecular chaperone SecB. This work shows directly that SecB binds with high affinity to unfolded maltose-binding protein but does not specifically recognize and bind the leader. Rather, the leader modulates folding to expose elements in the remainder of the polypeptide that are recognized by SecB.
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Affiliation(s)
- L L Randall
- Biochemistry/Biophysics Program, Washington State University, Pullman 99164-4660
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Abstract
After culturing mouse peritoneal cells in vitro for 4 days, high numbers of cells can be detected that secrete autoantibodies against isologous red blood cells (RBC), modified with the proteolytic enzyme bromelain (Brom). Plaque-forming cell numbers against mouse Brom RBC were significantly reduced by pretreating mouse Brom RBC prior to haemolytic assay with phospholipase C, an enzyme that hydrolyzes phospholipids, notably phosphatidylcholine. In contrast, further treatment of mouse Brom RBC with Brom, neuraminidase, beta-chymotrypsin, trypsin, or papain had no effect on plaque-forming cell numbers. These results show that phosphatidylcholine is an integral part of the mouse RBC autoantigen exposed by Brom treatment.
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Affiliation(s)
- S J Hardy
- School of Biological Sciences, Flinders University of South Australia, Bedford Park
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Fournier A, Hardy SJ, Clark KJ, Murray AW. Phorbol ester induces differential membrane-association of protein kinase C subspecies in human platelets. Biochem Biophys Res Commun 1989; 161:556-61. [PMID: 2735910 DOI: 10.1016/0006-291x(89)92635-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Human platelets contained proteins which cross-reacted with antisera specific for brain protein kinase C-alpha and -beta. When platelets were incubated with 12-O-tetradecanoylphorbol-13-acetate there was a rapid accumulation of protein kinase C-alpha in the particulate fraction associated with a loss of this subspecies from the soluble fraction. No particulate accumulation or soluble loss of protein kinase C-beta could be detected when platelets were incubated with the phorbol ester.
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Affiliation(s)
- A Fournier
- School of Biological Sciences, Flinders University, Bedford Park, South Australia
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Abstract
Passage of proteins across membranes during export from their site of synthesis to their final destination is mediated by leader peptides that paradoxically exhibit a unity of function in spite of a diversity of sequence. These leader peptides act in at least two stages of the export process: at entry into the pathway and subsequently during translocation across the membrane. How selectivity is imposed on the system in the absence of a consensus among the sequences of leader peptides is the main issue discussed here.
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Affiliation(s)
- L L Randall
- Biochemistry/Biophysics Program, Washington State University, Pullman 99164
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Abstract
Export of proteins from the bacterial cytoplasm to a final destination in the periplasm and outer membrane is one example of the fundamental process occurring in all cells whereby polypeptides are transferred across biological membranes. Investigations on a variety of different systems have indicated similarities in the mechanism of this process. In the cases of bacterial protein export and the transfer of polypeptides across the endoplasmic reticulum in eukaryotic cells the processes are so similar that understanding gleaned from studies of the one is usually directly applicable to the other. The study of protein export in E. coli has two advantages over that of eukaryotic secretion. Not only is there the possibility of doing sophisticated genetic experiments, but also one can carry out biochemical investigations in vivo, a facility not so readily available with eukaryotic organisms. Such studies have, for example, shown that membrane translocation can occur both cotranslationally and post-translationally, that export requires protonmotive force, that some component of the export apparatus prevents the exported protein from assuming its native structure in the cytosol, and that there are probably at least two functions for the leader sequence, one in targeting the protein to the export pathway and one in translocation across the membrane.
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Affiliation(s)
- S J Hardy
- Department of Biology, University of York, UK
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Hardy SJ, Holmgren J, Johansson S, Sanchez J, Hirst TR. Coordinated assembly of multisubunit proteins: oligomerization of bacterial enterotoxins in vivo and in vitro. Proc Natl Acad Sci U S A 1988; 85:7109-13. [PMID: 3050987 PMCID: PMC282133 DOI: 10.1073/pnas.85.19.7109] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In this paper we study the assembly, in vivo and in vitro, of a family of hexameric, heat-labile enterotoxins produced by diarrheagenic bacteria. The toxins, which consist of an A subunit and five B subunits, are assembled by a highly coordinated process that ensures secretion of the holotoxin complex. We show that (i) oxidation of cysteine residues in the B subunits is a prerequisite step for in vivo formation of B-subunit pentamers, (ii) reduction of dissociated B subunits in vitro abolishes their ability to reassemble, (iii) the kinetics of B-pentamer assembly in vivo can be mimicked under defined conditions in vitro, (iv) A subunits cannot associate with fully assembled B pentamers in vitro, and (v) A subunits cause an approximately 3-fold acceleration in the rate of B-subunit pentamerization in vivo, implying that A subunits play a coordinating role in the pathway of holotoxin assembly. The last finding is likely to be of general significance, since it provides a mechanism for preferentially excluding or favoring certain intermediates in the assembly of multisubunit proteins.
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Affiliation(s)
- S J Hardy
- Department of Biology, University of York, Great Britain
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Affiliation(s)
- L L Randall
- Biochemistry/Biophysics Program, Washington State University, Pullman 99164-4660
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Randall LL, Hardy SJ. Correlation of competence for export with lack of tertiary structure of the mature species: a study in vivo of maltose-binding protein in E. coli. Cell 1986; 46:921-8. [PMID: 3530497 DOI: 10.1016/0092-8674(86)90074-7] [Citation(s) in RCA: 392] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Sensitivity to proteolytic degradation was used to monitor folding of polypeptides in vivo. A correlation between competence for export and lack of stable tertiary structure was established by comparing the kinetics of folding of mutated precursor maltose-binding protein that carries a defective leader peptide with the kinetics of folding of wild-type precursor that is competent for export. It is proposed that during export a kinetic competition exists between productive translocation and folding of precursor intracellularly into a stable conformation that is not compatible with transfer.
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Cox KO, Hardy SJ. Autoantibodies against mouse bromelain-modified RBC are specifically inhibited by a common membrane phospholipid, phosphatidylcholine. Immunol Suppl 1985; 55:263-9. [PMID: 4007927 PMCID: PMC1453600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Sera from mice injected 4 days earlier with lipopolysaccharide lysed mouse RBC treated with bromelain (brom). This lytic activity was totally inhibited by including phosphatidylcholine at final concentrations of about 2 micrograms/ml, or more, in the lytic mixtures. In contrast, the lytic activity of antibodies against rat RBC was not inhibited, even at concentrations of phosphatidylcholine up to 2.5 mg/ml. Various components of the phosphatidylcholine molecule, and other lipids including the closely-related molecule dipalmitoyl phosphatidyl-dimethyl-ethanolamine which is identical to dipalmitoyl phosphatidylcholine, except for the absence of a CH2 group on the polar head group, did not inhibit lysis by the autoantibodies. Autoantibodies against mouse brom RBC, but not antibodies against rat RBC, bound to, and could be eluted from, phosphatidylcholine molecules attached to an insoluble matrix. Liposomes of phosphatidylcholine prepared in the presence of phosphatidic acid or phosphatidylinositol did not inhibit the lysis of mouse brom RBC by autoantibodies to the same extent as liposomes of only phosphatidylcholine. This suggests that phosphatidylcholine is recognized by the autoantibodies only if presented in a certain configuration. We suggest that the function of these autoantibodies may be to facilitate the removal of membrane-damaged cells from the body. Such cells may arise by the process of ageing, or because of the effects of infectious agents such as viruses.
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Hirst TR, Sanchez J, Kaper JB, Hardy SJ, Holmgren J. Mechanism of toxin secretion by Vibrio cholerae investigated in strains harboring plasmids that encode heat-labile enterotoxins of Escherichia coli. Proc Natl Acad Sci U S A 1984; 81:7752-6. [PMID: 6393126 PMCID: PMC392230 DOI: 10.1073/pnas.81.24.7752] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
A genetically engineered Vibrio cholerae strain from which the cholera toxin genes had previously been deleted was used as a host in which to study the expression and secretion of related toxins and their subunits. Recombinant plasmids encoding heat-labile enterotoxins (LTs) from Escherichia coli of human and porcine origin were expressed in the V. cholerae host, and this resulted in the secretion of the LTs into the extracellular milieu. The secreted LTs were isolated and it was found that the A subunits of human and porcine LT were "unnicked" polypeptides, which indicates that nicking is not obligatory for toxin secretion. V. cholerae strains were also constructed that harbored plasmids encoding either the A or the B subunits of human LT (A+B-, or A-B+). Approximately 90% of the B subunits were secreted from the A-B+ strain, while all of the A subunits expressed by the A+B- strain remained cell associated. This implies that strains synthesizing both subunits assemble the A and B subunits prior to their secretion. We propose that the entry of the toxin into the secretory step of the export pathway is mediated by a secretory apparatus that recognizes structural domains within the B subunit of LT.
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Hirst TR, Randall LL, Hardy SJ. Cellular location of enterotoxin in Escherichia coli. Biochem Soc Trans 1984; 12:189-91. [PMID: 6373432 DOI: 10.1042/bst0120189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Abstract
We demonstrated that both the A and B subunits of heat-labile enterotoxin from Escherichia coli are located in the periplasm. The toxin was shown to form aggregates in Tris-EDTA buffers which are routinely used for isolating membranes. The aggregates pellet upon centrifugation, and this may explain why several previous investigators have concluded that enterotoxin is associated with membranes.
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Abstract
An oligomer of the B subunit of heat-labile enterotoxin of Escherichia coli has been observed in minicells and in whole cells. There is a delay after synthesis of the B subunit before it appears in the oligomer. The delay is not due to slow processing of the precursor. A similar delay in oligomerization of the major outer membrane protein OmpF is also described.
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