Molecular mechanisms of insulin resistance

This review discusses recent advances in understanding of the structure and function of the insulin receptor and insulin action, and how these relate to the clinical aspects of insulin resistance associated with non-insulin-dependent diabetes and other disorders. Improved understanding of the molecular basis of insulin resistance could ultimately lead to a better understanding of the causation of these conditions and the design of rational therapy to ameliorate them. Here, particular attention is devoted to the initial events that follow the binding of insulin to its receptor, including changes in insulin receptor phosphorylation. Receptor-mediated insulin resistance may be a consequence of various factors including increased serine/threonine phosphorylation of the receptor with decreased tyrosine phosphorylation, receptor densitisation, auto-antibodies to the receptor and inherited structural defects in the insulin receptor. Defects in insulin action could also arise at post-receptor events particularly glucose transport. Other circulating hormones, such as the newly characterised islet amyloid polypeptide (amylin), may also cause insulin resistance

The universtiy in a developing free society : challenges to autonomy and academic freedom

The real point of democratic reform, what I have been calling institutional reform, is not just to change the complexion of researchers, teachers and students, nor just to change the location of research and teaching, to be truly meaning- fill, reform has to lead to a change in the orientation of these activities. Let me take a hypothetical example, one where you succeed in adding more black and female faces to the research and leaching establishment and even to shifting the location of that establishment mainly to historically black universities - say your most advanced medical research facilities come to be located at the University of Fort Hare, with researchers mainly black and female, but the facility is still oriented to proton beam research for special types of cancer, away from the public health needs of the people - what will you have achieved? I dare say you would then have joined the ranks of independent Africa. The key issue will still remain not addressed: who should centres of research and learning serve and how? This is why I think the real challenge for all of us, whether south or north of the Limpopo, whether black or brown, yellow or white, is to begin thinking of how to root African universities in African soil

Mortality analysis of people with severe mental illness transferred from longstay hospital to alternative care in the Life Esidimeni tragedy

A mortality analysis of the Life Esidimeni tragedy was precluded during the investigation by the Health Ombud by the lack of data integrity. Information on the mental healthcare users (MHCUs) transferred out of Life Esidimeni hospitals between October 2015 and June 2016 was subsequently collected by the Gauteng Department of Health, permitting statistical analysis. Survival rates were calculated according to gender and transfer destination and adjusted for patient age. Mortality was compared with that of the general population for the calendar year of 2016. Of the 1 442 MHCUs, 15% were transferred to specialised psychiatric hospitals and 85% to a rehabilitation centre or non-governmental residential facility. By the end of August 2017, 9% (n=131) of the cohort had died. Significant predictors of survival were younger age (p<0.0001) and transfer to a psychiatric institution (p=0.004). The age-adjusted death rate was 63/1 000 and the overall standardised mortality ratio (SMR) was 4.9 (95% confidence interval (CI) 3.92 - 5.80), with an SMR of 3.9 (95% CI 2.95 - 4.86) for men and 6.3 (95% CI 4.22 - 8.38) for women. The excess deaths are therefore quantified, and the high-risk environment of the rehabilitation centre and residential facilities confirmed. High mortality among MHCUs is unlikely to be confined to the Life Esidimeni tragedy; monitoring of preventable deaths in this vulnerable population is recommended

First-Trimester Circulating 25-Hydroxyvitamin D Levels and Development of Gestational Diabetes Mellitus

OBJECTIVE-To investigate the association between first-trimester maternal serum levels of 25-hydroxyvitamin D (25-OH-D) as measured by liquid chromatography-tandem mass spectrometry and development of gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS-We conducted a case-control study involving 248 women in the first-trimester of pregnancy, 90 of whom developed GDM and 158 remained normoglycemic. RESULTS-Although booking 25-OH-D levels correlated negatively with 2-h glucose postoral glucose tolerance test and positively with HDL cholesterol, as well as with ethnicity, obesity, and smoking (all P < 0.05), there were no statistically significant differences in baseline maternal mean 25-OH-D levels between those who subsequently developed GDM, 18.9 ng/mL (SD 10.7) and those who remained normoglycemic, 19.0 ng/mL (10.7) (P = 0.874), even after adjustment for possible confounders including sampling month (P = 0.784). CONCLUSIONS-Our large and well-phenotyped prospective study did not find evidence of an association between first-trimester maternal levels of 25-OH-D and subsequent development of GDM

First-Trimester Prediction of Gestational Diabetes Mellitus: Examining the Potential of Combining Maternal Characteristics and Laboratory Measures

OBJECTIVE Predictors of gestational diabetes mellitus (GDM) have been widely studied, but few studies have considered multiple measures. Our objective was to integrate several potential GDM predictors with consideration to both simple and novel measures and to determine the extent to which GDM can be predicted in the first trimester. RESEARCH DESIGN AND METHODS We identified first-trimester maternal samples from 124 women who developed GDM and 248 control subjects who did not. We gathered data on age, BMI, parity, race, smoking, prior GDM, family history of diabetes, and blood pressure. Using retrieved samples, we measured routine (lipids, high-sensitivity C-reactive protein, and gamma-glutamyltransferase) and novel (adiponectin, E-selectin, and tissue plasminogen activator [t-PA]) parameters. We determined independent predictors from stepwise regression analyses, calculated areas under the receiver-operating characteristic curves (AUC-ROC), and integrated discrimination improvement (IDI) for relevant models. RESULTS Compared with control subjects, women who subsequently developed GDM were older, had higher BMIs, were more likely to be of Asian origin, had a history of GDM or family history of type 2 diabetes, and had higher systolic blood pressure (P < 0.05 for all). With regard biochemical measures, stepwise analyses identified only elevated t-PA and low HDL cholesterol levels as significant (P <= 0.015) independent predictors of GDM beyond simple non-laboratory-based maternal measures. Their inclusion improved the AUC-ROC from 0.824 to 0.861 and IDI by 0.052 (0.017-0.115). CONCLUSIONS GDM can be usefully estimated from a mix of simple questions with potential for further improvement by specific blood measures (lipids and t-PA)

Data and Safety Monitoring of COVID-19 Vaccine Clinical Trials

To speed the development of vaccines against SARS-CoV-2, the United States Federal Government has funded multiple phase 3 trials of candidate vaccines. A single 11-member data and safety monitoring board (DSMB) monitors all government-funded trials to ensure coordinated oversight, promote harmonized designs, and allow shared insights related to safety across trials. DSMB reviews encompass 3 domains: (1) the conduct of trials, including overall and subgroup accrual and data quality and completeness; (2) safety, including individual events of concern and comparisons by randomized group; and (3) interim analyses of efficacy when event-driven milestones are met. Challenges have included the scale and pace of the trials, the frequency of safety events related to the combined enrollment of over 100 000 participants, many of whom are older adults or have comorbid conditions that place them at independent risk of serious health events, and the politicized environment in which the trials have taken place

Priming by Chemokines Restricts Lateral Mobility of the Adhesion Receptor LFA-1 and Restores Adhesion to ICAM-1 Nano-Aggregates on Human Mature Dendritic Cells

LFA-1 is a leukocyte specific β2 integrin that plays a major role in regulating adhesion and migration of different immune cells. Recent data suggest that LFA-1 on mature dendritic cells (mDCs) may function as a chemokine-inducible anchor during homing of DCs through the afferent lymphatics into the lymph nodes, by transiently switching its molecular conformational state. However, the role of LFA-1 mobility in this process is not yet known, despite that the importance of lateral organization and dynamics for LFA-1-mediated adhesion regulation is broadly recognized. Using single particle tracking approaches we here show that LFA-1 exhibits higher mobility on resting mDCs compared to monocytes. Lymphoid chemokine CCL21 stimulation of the LFA-1 high affinity state on mDCs, led to a significant reduction of mobility and an increase on the fraction of stationary receptors, consistent with re-activation of the receptor. Addition of soluble monomeric ICAM-1 in the presence of CCL21 did not alter the diffusion profile of LFA-1 while soluble ICAM-1 nano-aggregates in the presence of CCL21 further reduced LFA-1 mobility and readily bound to the receptor. Overall, our results emphasize the importance of LFA-1 lateral mobility across the membrane on the regulation of integrin activation and its function as adhesion receptor. Importantly, our data show that chemokines alone are not sufficient to trigger the high affinity state of the integrin based on the strict definition that affinity refers to the adhesion capacity of a single receptor to its ligand in solution. Instead our data indicate that nanoclustering of the receptor, induced by multi-ligand binding, is required to maintain stable cell adhesion once LFA-1 high affinity state is transiently triggered by inside-out signals.Peer ReviewedPostprint (published version

The African intellectuals’ project

Soon after taking the position of editor of IJARS at the beginning of 2019, I was contacted by the dean of Unisa’s College of Graduate Studies (CGS), Prof. Lindiwe Zungu, who informed me that the university’s principal and vice-chancellor, Prof. Mandla Makhanya, had decided to revive his project, the African Intellectuals’ Project (AIP). I was asked to coordinate this project, through which Makhanya sought to invite scholars, academics, and intellectuals, both on and outside of the African continent, to deliver presentations reflecting on the ills afflicting Africa and, at the same time, to offer possible solutions. In pursuing the AIP, Prof. Makhanya was carrying on a perennial tradition

Body size modifies the relationship between maternal serum 25-hydroxyvitamin D concentrations and gestational diabetes in high-risk women

Obesity increases the risk of low 25-hydroxyvitamin D (25(OH) D) concentrations and gestational diabetes (GDM). We explored whether the association between GDM and change in 25(OH) D concentrations measured in the first (7-18 wk) and second (20-27 wk) trimesters of pregnancy is dependent on maternal BMI. The study was a prospective study of 219 women with BMI of >= 30 kg/m2, a history of GDM, or both. The participants were stratified by first-trimester BMI: BMI of = 35 kg/m(2). In the BMI group >= 35 kg/m(2), those who did not develop GDM during the follow-up showed higher increase in serum 25(OH) D concentrations compared with women who developed GDM (43.2 vs. 11.5%; P <0.001). No associations between 25(OH) D concentrations and GDM were observed in other BMI groups. These findings give an important aspect of the role of maternal body size in the association between vitamin D and GDM in high-risk women.Peer reviewe