Abstract: The incidence of diffuse large B-cell lymphoma (DLBCL) increases with older age. Thus, subgroup reporting for older adults in clinical trials is necessary to determine the relevance of novel therapy outcomes to this vulnerable population. This study assessed subgroup reporting of older adults (aged ≥65 years) enrolled in US Food and Drug Administration and European Medicines Agency registration trials for DLBCL between 2017 and 2023. Clinical efficacy end points for each trial were extracted from ClinicalTrials.gov registry data and study protocols. Primary and secondary publications reporting on included studies were identified through a systematic review process within Covidence. Ten therapies with 12 indications were approved between 2017 and 2023. Ninety-two publications were included for data extraction. The availability and completeness of older adult subgroup data relating to protocol-defined efficacy end points, as well as data relating to baseline patient characteristics, health-related quality-of-life outcomes, and toxicity outcomes, were assessed according to predefined criteria. Of 12 primary end points, 10 (83.4%) were reported completely, 1 (8.3%) was reported partially, and 1 (8.3%) was not reported among older subgroups. Of 66 secondary end points, 25 (37.9%) were completely reported, 6 (9.1%) were partially reported, and 35 (53.1%) were unreported. Baseline characteristics, health-related quality-of-life outcomes, and toxicities outcomes among older adults were mostly unreported. This analysis highlights a need for improvement in older adult subgroup reporting in DLBCL trials, particularly among secondary end points.

Mobile applications are widely used in epilepsy, although their impact on clinical effectiveness (CE) and their feasibility, acceptability, and usability (FAU) remain unclear. We conducted a systematic review investigating CE and FAU of epilepsy mobile applications using MEDLINE and Embase from database inception to June 21, 2024. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting standards. The protocol was registered on PROSPERO (CRD42019134848). In duplicate, we determined study quality using the Newcastle-Ottawa Quality Assessment Scale (NOQAS) and the Joanna Briggs Critical Appraisal Checklist (to determine eligibility for inclusion), risk of bias using the Cochrane Risk of Bias tool, and usability study quality using the 15-point Silva scale. We identified 8953 studies, of which 20 were included. Twelve (60.0%) addressed CE, nine (45.0%) acceptability, five (25.0%) usability, and eight (40.0%) feasibility. Five (25.0%) evaluated CE and FAU. Studies comprised prospective cohort (n = 9, 45.0%), pilot (n = 3, 15.0%), randomized controlled trial (n = 7, 35.0%), and pre/post (n = 1, 5.0%) designs. Most apps were used for self-management or to enhance education or communication between patients and providers. Cohort studies demonstrated fair quality (median NOQAS score = 5, interquartile range [IQR] = 5.0-5.8), whereas of seven randomized controlled trials, four (57.1%) had some concern for bias. Usability studies demonstrated high quality (median Silva score = 10, IQR = 10-11). Apps were predominantly intended for patient use (n = 9, 75.0%). Symptom reporting and medication management were the most common app targets in both CE and FAU studies (n = 8, 66.7%; n = 9, 69.2%), although FAU studies more frequently used monitoring or tracking (n = 10, 76.9%) and reminder setting (n = 10, 76.9%) than CE apps (n = 7, 58.3%). Investigations of application use most commonly studied CE and patient-facing apps. Additional high-quality evidence is necessary to evaluate the CE and FAU of app use in epilepsy to work toward the standardization of FAU metrics and development of implementation guidelines.

Introduction: Diffuse large B-cell lymphoma (DLBCL) is primarily a disease of older adults (OA). The median age at diagnosis is in the mid-sixties, and 55% of patients (pts) are >=65 years (yrs) at time of diagnosis. The United States Food and Drug Administration (FDA) has recommended in its guideline document for adequate representation of OA in clinical trials to maintain the generalizability of results. In addition to increasing participation, detailed subgroup reporting of the OA cohort enrolled to registrational trials is critical to contextualise efficacy and toxicities in this subgroup. In this systematic review, we analyse subgroup reporting of baseline pt characteristics, efficacy, toxicities, and quality of life (QoL) of OA in contemporary FDA and European Medicines Agency (EMA) registration trials between 2014 to 2023, leading to approval between 2017 and 2023. Methods: FDA and EMA approvals for DLBCL between 2017 and 2023 were obtained from publicly available FDA and EMA resources. Literature searches, according to trial name, National Clinical Trial registration number, and drug name, were conducted in Medline ALL (Ovid), Embase, Scopus, Web of Science Core Collection, Cochrane CENTRAL, and CINAHL, for all publications relating to included trials. Study efficacy endpoints were extracted from ClinicalTrials.gov registry data, published endpoints, and the most recent study protocol/statistical data analysis plan. Primary and secondary publications reporting on included studies were identified through a two-step screening process within Covidence. The availability and completeness of older adult subgroup data relating to protocol-defined efficacy endpoints, as well as data relating to baseline pt characteristics, health-related quality of life outcomes, and toxicity outcomes, were assessed according to predefined criteria. Results: Between 2017 and 2023, the FDA and EMA approved 10 therapies with 12 indications for DLBCL, based on 12 registration trials (2017-ZUMA-1; 2018-JULIET; 2019-GO29365; 2020-L-MIND, SADAL; 2021- TRANSCEND, LOTIS-2; 2022-ZUMA-7, TRANSFORM; 2023-POLARIX, EPCORE NHL-1, NP30179). 11 trials were in the setting of relapsed/refractory disease. 1 trial, POLARIX, was in the first-line setting. 5 trials assessed CAR-T cell therapies, 3 antibody-drug-conjugates, 2 bispecific antibodies, 1 monoclonal antibody, and 1 a small molecule. A total of 7369 results were retrieved through a literature search of registrational trials, and 92 were included for data extraction. 12 primary endpoints (ORR, CRR, EFS, PFS) and 66 secondary endpoints (OS, PFS, RFS, ORR, CRR, PRR, DOR, BOR, DCR, 2-year EFS, 2-year PFS, 2-year DFS) were assessed. Of the 12 primary endpoints, 10 (83.4%) were reported completely, 1 (8.3%) partially, and 1 (8.3%) was not reported among older subgroups. Of the 66 secondary endpoints, 25/66 (37.9%) were completely reported, 6/66 (9.1%) were partially reported, and 35/66 (53.0%) were unreported. A dedicated secondary report on OA was available for five trials (ZUMA-1, SADAL, LOTIS-2, ZUMA-7, and POLARIX). The existence of dedicated reports correlated significantly with the completeness of reporting (for primary and secondary endpoints) (p=0.03). Baseline characteristics were completely reported in 4 (ZUMA-1, ZUMA-7, LOTIS-2, POLARIX) (33.3%) and partially reported in 1 (SADAL) (8.4%) trial. 7 of 12 (58.3%) trials did not report basic baseline characteristics in older subgroups. QoL using a validated instrument was assessed in 8/12 (66.7%) trials. QoL was completely reported in 1/8 (ZUMA-7) (12.6%) trial, partially in 2/8 (LOTIS-2, POLARIX) (25.0%) trials, and was unreported in 5/8 (TRANSCEND, JULIET, TRANSFORM, SADAL, EPCORE NHL-1) (62.5%) trials. None of the trials completely reported toxicities in older OA, but 6 (ZUMA-1, ZUMA-7, TRANSCEND, SADAL, LOTIS-2, POLARIX) (50%) reported partially, whereas the remaining 6 (50%) trials left toxicities unreported in OA. Conclusion: Our analysis highlights a need for improvement in OA subgroup reporting in DLBCL trials, particularly among secondary endpoints. Standardization of subpopulation analysis in OA and dedicated trials and abstracts reporting the data will better enable a benefit-risk assessment of new agents for OA with DLBCL.

Abstract Given that the use of breast implants for both cosmetic and reconstructive purposes is growing in the United States, an evaluation of factors that may affect the outcome of breast implant surgery is needed. A systematic review was conducted to evaluate the question: Does a personal or family history of autoimmune disease affect outcomes in breast implant surgery? The literature search yielded 2425 records, but after removal of duplicates, abstract screening, and full-text assessment, only 2 studies met the inclusion criteria for the final review. Both studies provided level III evidence and the average Methodological Index for Non-Randomized Studies score was 16.5 (range, 15–18 of 24), indicating a fair level of evidence overall. This systematic review found no evidence to support that a diagnosis of an autoimmune disease and/or a family history of autoimmune diseases will lead to poor surgical outcomes in breast implant surgery. Further study is warranted.

Given that the use of breast implants for both cosmetic and reconstructive purposes is growing in the United States, an evaluation of factors that may affect the outcome of breast implant surgery is needed. A systematic review was conducted to evaluate the question: Does a personal or family history of autoimmune disease affect outcomes in breast implant surgery? The literature search yielded 2425 records, but after removal of duplicates, abstract screening, and full-text assessment, only 2 studies met the inclusion criteria for the final review. Both studies provided level III evidence and the average Methodological Index for Non-Randomized Studies score was 16.5 (range, 15-18 of 24), indicating a fair level of evidence overall. This systematic review found no evidence to support that a diagnosis of an autoimmune disease and/or a family history of autoimmune diseases will lead to poor surgical outcomes in breast implant surgery. Further study is warranted.

Mobile applications, or “apps”, are widely used by people with epilepsy, their caregivers, and providers. The impact of these apps on the clinical effectiveness (CE) and feasibility, acceptability, or usability (FAU) in epilepsy remains unclear. To conduct a systematic review of studies investigating the CE and FAU of mobile applications in epilepsy. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards and was registered with the Prospective Register of Systematic Reviews (PROSPERO; CRD42019134848). The search was conducted using MEDLINE ALL (Ovid) and EMBASE (Ovid) from database inception to April 2022. At the screening phase, we excluded conference abstracts, non-English language and review articles, as well as articles studying video telehealth. We determined study quality for case-control or cohort studies using the Newcastle-Ottawa Quality Assessment Scale (NOQAS) and bias in randomized studies using the Cochrane Collaboration Handbook Risk of Bias (RoB) tool. We assessed usability study quality using the validated 15-point Silva scale. Study characteristics were analyzed using summary statistics. We identified 6,768 studies, of which 13 (0.2%) were included. Of the 13 studies, 8 (61.5%) addressed CE, 6 (46.2%) acceptability, 5 (38.5%) usability, and 4 (30.8%) feasibility. Four studies (31.0%) evaluated both CE and FAU. Studies comprised prospective cohort (N=6, 46.2%), pilot (N=3, 23.1%), randomized trial (N=3, 23.1%) and pre/post (N=1, 7.7%) designs. Overall, cohort studies demonstrated fair quality (median NOQAS score 5, interquartile range [IQR] 5.0 - 5.8), whereas 2 (66.7%) randomized studies had some concern for bias. Usability studies demonstrated high methodological quality (median Silva score 10, IQR 10 - 11). Apps were most frequently studied in patient users (N=7 (87.5%) CE and 8 (100%) FAU studies). The most common app target in CE studies was physical health (N=5, 62.5%) contrasting with symptom management (N=7, 87.5%) in FAU studies. We found that studies of app use in epilepsy most commonly studied CE and evaluated patient-facing apps. Despite high methodological quality in usability studies and several randomized CE studies, cohort and randomized studies demonstrated fair quality and moderate bias, respectively. Additional high-quality evidence is necessary to evaluate the CE and FAU of app use in epilepsy.

Purpose The optimal age for minimally invasive repair of pectus excavatum (MIRPE) is unclear; this study investigates the differences in complication rates among different age groups undergoing repair. Methods PubMed and Embase databases were searched from inception to October 2020. To assess age as a risk factor for complications, odds ratios from relevant studies were analyzed using the Mantel–Haenszel method with a random-effects model for younger vs older patients. Specific complication rates were compared between the two cohorts using a chi-squared test. Results Of the 4448 studies retrieved, 25 studies stratified complication data by age groups. From these studies, ten studies compared groups at ages < 18 and ≥ 18 and four studies compared ages < 20 and ≥ 20, and one study compared ages < 19 and ≥ 19. These fifteen studies reported on 5978 patients, with 1188 complications, for a complication rate of 19.87%. Older patients were more likely to have complications in a pooled analysis of studies comparing older vs younger patients (OR = 1.66, 95% CI = 1.28–2.14, heterogeneity I 2 = 49%). Specifically, older patients were significantly more likely to experience pneumothorax, pleural effusion, wound infection, bar displacement, and reoperations. Conclusion Increased age is a risk factor for complications of MIRPE. This supports repair of pectus excavatum prior to late adolescence.

Objective: Systematic reviews and meta-analyses (SRs/MAs) are designed to be rigorous research methodologies that synthesize information and inform practice. An increase in their publication runs parallel to quality concerns and a movement toward standards to improve reporting and methodology. With the goal of informing the guidance librarians provide to SR/MA teams, this study assesses online journal author guidelines from an institutional sample to determine whether these author guidelines address SR/MA methodological quality. Methods: A Web of Science Core Collection (Clarivate) search identified SRs/MAs published in 2014–2019 by authors affiliated with a single institution. The AMSTAR 2 checklist was used to develop an assessment tool of closed questions specific to measures for SR/MA methodological quality in author guidelines, with questions added about author guidelines in general. Multiple reviewers completed the assessment. Results: The author guidelines of 141 journals were evaluated. Less than 20% addressed at least one of the assessed measures specific to SR/MA methodological quality. There was wide variation in author guidelines between journals from the same publisher apart from the American Medical Association, which consistently offered in-depth author guidelines. Normalized Eigenfactor and Article Influence Scores did not indicate author guideline breadth. Conclusions: Most author guidelines in the institutional sample did not address SR/MA methodological quality. When consulting with teams embarking on SRs/MAs, librarians should not expect author guidelines to provide details about the requirements of the target journals. Librarians should advise teams to follow established SR/MA standards, contact journal staff, and review SRs/MAs previously published in the journal.

Significance Statement Biomarker studies in the setting of CKD have increased considerably within the past 15 years, but vary significantly by design and clinical context. The authors conducted a systematic review and meta-analysis to summarize the prognostic value of preclinical plasma and urine biomarkers for CKD outcomes (incident CKD, CKD progression, or incident ESKD), including 129 studies in the meta-analysis. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) among some of the most studied CKD biomarkers were 2.17 (95% CI, 1.91 to 2.47) for plasma TNFR1, 1.21 (95% CI, 1.15 to 1.28) for plasma FGF23, 2.07 (95% CI, 1.82 to 2.34) for plasma TNFR2, 1.10 (95% CI, 1.05 to 1.16) for urine KIM-1, and 1.12 (95% CI, 1.06 to 1.19) for urine NGAL. The study’s findings suggest these biomarkers merit assessment of their performance in clinical practice. Background Sensitive and specific biomarkers are needed to provide better biologic insight into the risk of incident and progressive CKD. However, studies have been limited by sample size and design heterogeneity. Methods In this assessment of the prognostic value of preclinical plasma and urine biomarkers for CKD outcomes, we searched Embase (Ovid), MEDLINE ALL (Ovid), and Scopus up to November 30, 2020, for studies exploring the association between baseline kidney biomarkers and CKD outcomes (incident CKD, CKD progression, or incident ESKD). We used random-effects meta-analysis. Results After screening 26,456 abstracts and 352 full-text articles, we included 129 studies in the meta-analysis for the most frequently studied plasma biomarkers (TNFR1, FGF23, TNFR2, KIM-1, suPAR, and others) and urine biomarkers (KIM-1, NGAL, and others). For the most frequently studied plasma biomarkers, pooled RRs for CKD outcomes were 2.17 (95% confidence interval [95% CI], 1.91 to 2.47) for TNFR1 (31 studies); 1.21 (95% CI, 1.15 to 1.28) for FGF-23 (30 studies); 2.07 (95% CI, 1.82 to 2.34) for TNFR2 (23 studies); 1.51 (95% CI, 1.38 to 1.66) for KIM-1 (18 studies); and 1.42 (95% CI, 1.30 to 1.55) for suPAR (12 studies). For the most frequently studied urine biomarkers, pooled RRs were 1.10 (95% CI, 1.05 to 1.16) for KIM-1 (19 studies) and 1.12 (95% CI, 1.06 to 1.19) for NGAL (19 studies). Conclusions Studies of preclinical biomarkers for CKD outcomes have considerable heterogeneity across study cohorts and designs, limiting comparisons of prognostic performance across studies. Plasma TNFR1, FGF23, TNFR2, KIM-1, and suPAR were among the most frequently investigated in the setting of CKD outcomes.

Background: Early life exposures impact immune system development and therefore the risk of immune-mediated diseases, including inflammatory bowel disease (IBD). We systematically reviewed the impact of pre-, peri-, and postnatal exposures up to the age of five years on subsequent IBD diagnosis. Methods: We identified case-control and cohort studies reporting on the association between early life environmental factors and Crohn's disease (CD), ulcerative colitis (UC), or IBD overall. Databases were search from their inception until May 24th, 2019 until July 14th, 2020. We conducted meta-analyses for quantitative review of relevant risk factors that were comparable across studies and qualitative synthesis of the literature for a wide range of early life exposures, including maternal health and exposures during pregnancy, perinatal factors, birth month and related-factors, breastfeeding, hygiene-related factors and social factors, immigration, antibiotics, offspring health, including infections, and passive smoking. PROSPERO registration: CRD42019134980. Findings: Prenatal exposure to antibiotics (OR 1.8; 95% CI 1.2-2.5) and tobacco smoke (OR 1.5; 95% CI 1.2-1.9), and early life otitis media (OR 2.1; 95% CI 1.2-3.6) were associated with IBD. There was a trend towards an association between exposure to antibiotics in infancy and IBD (OR: 1.7, 95% CI 0.97, 2.9), supported by positive data on population-based data. Breastfeeding was protective against IBD. Other early life risk factors had no association with IBD, but data were limited and heterogenous. Interpretation: Early life is an important period of susceptibility for IBD development later in life. Tobacco smoke, infections and antibiotics were associated positively, and breastfeeding was associated negatively with IBD. Our findings offer an opportunity to develop primary prevention strategies. (C) 2021 The Authors. Published by Elsevier Ltd.

Objective: This study aimed to evaluate the proportion of patients with seizures and electroencephalography (EEG) abnormalities in autoimmune encephalitis (AE) and its most common subtypes. Methods: This systematic review followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standards and was registered with the International Prospective Register of Systematic Reviews (PROSPERO). We searched Medline All, Embase, and PsychINFO in Ovid from inception to June 2019 for articles pertaining to AE and seizure. Included studies reported seizure and/or EEG data in cohorts of >= 10 AE patients. Patient demographics, antibody type, seizure incidence, and EEG findings were extracted. Review of studies and data extraction were performed in duplicate. In addition to descriptive analysis, quantitative synthesis stratified by autoantibody subtype was performed with logistic regression and chi-square analyses. Results: Our search yielded 3856 abstracts: 1616 were selected for full-text review and 118 studies met eligibility criteria. Of 3722 antibody-positive AE patients, 2601 (69.9%) had clinical seizures during the course of their illness. Of the 2025 patients with antibody-positive AE and available EEG data, 1718 (84.8%) had some EEG abnormality (eg, epileptiform discharges, slowing, and so on). Anti- N-methyl-d-aspartate (NMDA) receptor encephalitis (anti-NMDARE) was the most commonly reported type of AE (1985/3722, 53.3%). Of the anti-NMDARE patients with available seizure or EEG data, 71.8% (n = 1425/1985) had clinical seizures during their illness, and 89.7% (n = 1172/1306) had EEG abnormalities. For all AE patients and in the anti-NMDARE subpopulation, seizures were more common in younger patients (p < .05). Significance: This systematic review provides an estimate of the proportion of AE patients with seizures, confirming the magnitude of seizure burden in this population. Prospective studies are needed to understand population-based prevalence of seizures, identify factors associated with seizures, and evaluate particular EEG findings as biomarkers of seizures and outcomes in AE.

Objective: To explore the sex-specific association of non-statin classes of drugs in reducing cardiovascular outcomes. Methods: Published data search up to November 2019 reporting primary outcomes that approximate with major vascular events (MVEs) after treatment with non-statin group of drugs was performed. The primary outcome was the sex-specific association with MVEs. Random-effects meta-analysis was performed to estimate relative risk (RR) of the individual classes of therapies. Results: Seven Randomized Clinical Trials (RCTs) including 122,164 patients were included in our analysis. Four studies compared the Triglyceride (TG)-lowering group of drugs with placebo and 3 studies compared low-density lipoprotein cholesterol (LDL-c) lowering drugs with placebo. Overall, with non-statin drugs, there was no difference in the risk reduction of cardiovascular (CV) events between men (RR 0.86; 95% CI 0.79-0.94, p-value <0.001) and women (RR 0.88; 95% CI 0.83-0.93, p-value 0.91). However, TG targeting interventions showed no cardiovascular outcome benefits in men (RR 0.85; 95% CI 0.71-1.02, p-value <0.001) while no significant benefit was seen in women (RR 0.87; 95% CI 0.77-0.98, p value = 0.85). No such difference existed in non-statin LDL-c lowering group of drugs in between men (RR 0.88; 95% CI 0.81-0.94, p value = 0.18) and women (RR 0.88; 95% CI 0.82-0.94, p value = 0.46). However, lowering of TG was only associated with a higher risk reduction of CV events (RR 0.86; 95% CI 0.77-0.95, p value = 0.03) in the entire study population. Conclusion: Non-statin group of drugs was effective in reducing adverse CV outcomes for both sexes. Lowering TG was associated with higher risk reduction in CV events in general. (C) 2020 Elsevier Inc. All rights reserved.

Beta-Blockers (BB) reduce mortality in heart failure with reduced ejection fraction (HFrEF). Current guidelines do not list cocaine use as a contraindication to BB therapy in HFrEF but acknowledge that its safety and benefits are uncertain. We performed a meta-analysis to examine the safety and

Perfusing fixatives through the cerebrovascular system is the gold standard approach in animals to prepare brain tissue for spatial biomolecular profiling, circuit tracing, and ultrastructural studies such as connectomics. Translating these discoveries to humans requires examination of postmortem autopsy brain tissue. Yet banked brain tissue is routinely prepared using immersion fixation, which is a significant barrier to optimal preservation of tissue architecture. The challenges involved in adopting perfusion fixation in brain banks and the extent to which it improves histology quality are not well defined. We searched four databases to identify studies that have performed perfusion fixation in human brain tissue and screened the references of the eligible studies to identify further studies. From the included studies, we extracted data about the methods that they used, as well as any data comparing perfusion fixation to immersion fixation. The protocol was preregistered at the Open Science Framework: https://osf.io/cv3ys/ . We screened 4489 abstracts, 214 full-text publications, and identified 35 studies that met our inclusion criteria, which collectively reported on the perfusion fixation of 558 human brains. We identified a wide variety of approaches to perfusion fixation, including perfusion fixation of the brain in situ and ex situ, perfusion fixation through different sets of blood vessels, and perfusion fixation with different washout solutions, fixatives, perfusion pressures, and postfixation tissue processing methods. Through a qualitative synthesis of data comparing the outcomes of perfusion and immersion fixation, we found moderate confidence evidence showing that perfusion fixation results in equal or greater subjective histology quality compared to immersion fixation of relatively large volumes of brain tissue, in an equal or shorter amount of time. This manuscript serves as a resource for investigators interested in building upon the methods and results of previous research in designing their own perfusion fixation studies in human brains or other large animal brains. We also suggest several future research directions, such as comparing the in situ and ex situ approaches to perfusion fixation, studying the efficacy of different washout solutions, and elucidating the types of brain donors in which perfusion fixation is likely to result in higher fixation quality than immersion fixation.

Active transport of substrates across cytoplasmic membranes is of great physiological, medical and pharmaceutical importance. The glycerol-3-phosphate (G3P) transporter (GlpT) of the E. coli inner membrane is a secondary active antiporter from the ubiquitous major facilitator superfamily that couples the import of G3P to the efflux of inorganic phosphate (Pi) down its concentration gradient. Integrating information from a novel combination of structural, molecular dynamics simulations and biochemical studies, we identify the residues involved directly in binding of substrate to the inward-facing conformation of GlpT, thus defining the structural basis for the substrate-specificity of this transporter. The substrate binding mechanism involves protonation of a histidine residue at the binding site. Furthermore, our data suggest that the formation and breaking of inter- and intradomain salt bridges control the conformational change of the transporter that accompanies substrate translocation across the membrane. The mechanism we propose may be a paradigm for organophosphate:phosphate antiporters.

Secondary active transport of substrate across the cell membrane is crucial to many cellular and physiological processes. The crystal structure of one member of the secondary active transporter family, the sn-glycerol-3-phosphate (G3P) transporter (GlpT) of the inner membrane of Escherichia coli, suggests a mechanism for substrate translocation across the membrane that involves a rocker-switch-type movement of the protein. This rocker-switch mechanism makes two specific predictions with respect to kinetic behavior: the transport rate increases with the temperature, whereas the binding affinity of the transporter to a substrate is temperature-independent. In this work, we directly tested these two predictions by transport kinetics and substrate-binding experiments, integrating the data on this single system into a coherent set of observations. The transport kinetics of the physiologically relevant G3P-phosphate antiport reaction were characterized at different temperatures using both E. coli whole cells and GlpT reconstituted into proteoliposomes. Substrate-binding affinity of the transporter was measured using tryptophan fluorescence quenching in detergent solution. Indeed, the substrate transport velocity of GlpT increased dramatically with temperature. In contrast, neither the apparent Michaelis constant (Km) nor the apparent substrate-binding dissociation constant (Kd) showed temperature dependence. Moreover, GlpT-catalyzed G3P translocation exhibited a completely linear Arrhenius function with an activation energy of 35.2 kJ mol-1 for the transporter reconstituted into proteoliposomes, suggesting that the substrate-loaded transporter is delicately poised between the inward- and outward-facing conformations. When these results are taken together, they are in agreement with a rocker-switch mechanism for GlpT.

Postprandial triglyceride-rich lipoproteins (TRL) exert proatherogentic effects at the arterial wall, including lipid deposition. Following consumption of a mixed meal (1,200 kcal), plasma-mediated cellular free cholesterol (FC) efflux, lecithin:cholesterol acyltransferase (LCAT), and cholesteryl ester transfer protein (CETP) activities were determined in subjects (n = 12) displaying type IIB hyperlipidemia and compared with those in a normolipidemic control group (n = 14). The relative capacity of plasma to induce FC efflux from Fu5AH cells via the SR-BI receptor was significantly increased 4 It postprandially (+23%; P < 0.005) in the type IIB group, whereas it remained unchanged for postprandial plasma from normolipidemic subjects. LCAT activity was significantly elevated 2 It postprandially in both the IIB and control groups, (+46% and +36%, respectively; P < 0.005 vs. respective baseline value). In type IIB subjects, total cholesteryl ester (CE) mass transfer from HDL to total TRL [chylomicrons (CMs) + VLDL-1 + VLDL-2 + IDL] increased progressively from 15 +/- 2 mug CE/h/ml at baseline to 28 +/- 2 mug CE transferred/h/ml (+87%; P = 0.0004) at 4 h postprandially. CE transfer to CMs and VLDL,1 was preferentially stimulated (2.6-fold and 2.3-fold respectively) at 4 h in IIB subjects and occurred concomitantly, with elevation in mass and particle number of both CMs (2.3-fold) and VLDL-1 (1.3-fold). Furthermore, in type IIB subjects, CETP-mediated total CE flux over the 8 It postprandial period from HDL to potentially atherogenic TRL was significantly enhanced, and notably to VLDL-1 (32-fold elevation; P < 0.005), relative to control subjects. Such CE transfer flux was reflected in a significant postprandial increase in CE-TG ratio in both CMs and VLDL-1 in type IIB plasmas. In conclusion, HDL-CE is preferentially targeted to VLDL-1 via the action of CETP during alimentary lipemia, thereby favoring formation and accumulation of atherogenic CE-rich remnant particles.