Effects of Walnut-Rich Diet on Cation-Handling Proteins in the Heart of Healthy and Metabolically Compromised Male Rats.

The transport of cations in the cardiomyocytes, crucial for the functioning of the heart, can be affected by walnut diet due to the high content of polyunsaturated fatty acids. Healthy and metabolically compromised rats (drinking 10% fructose solution) were subjected to a diet supplemented with 2.4 g of walnuts for 6 weeks to investigate the effect on proteins involved in cation transport in the heart cells. Fructose increased the level of the α1 subunit of Na+/K+-ATPase and the phosphorylation of extracellular signal-regulated kinase 1/2 in the heart of control and walnut-eating rats, while elevated L-type calcium channel α (LTCCα), sodium-calcium exchanger 1 (NCX1), and Maxi Kα level were observed only in rats that did not consume walnuts. However, walnuts significantly increased the cardiac content of LTCC, NCX1, and Maxi Kα, as well as Kir6.1 and SUR2B subunits of KATP channel, but only in fructose-naive rats. In animals that drank fructose, a significant increasing effect of walnuts was observed only in Akt kinase phosphorylation, which may be a part of the antiarrhythmic mechanism of decreasing cation currents in cardiomyocytes. The walnut diet-induced increase in LTCC and NCX1 expression in healthy rats may indicate intense cardiac calcium turnover, whereas the effect on Kir6.1 and SUR2B subunits suggests stimulation of KATP channel transport in the cardiac vasculature. The effects of walnuts on the cation-handling proteins in the heart, mostly limited to healthy animals, suggest the possible use of a walnut-supplemented diet in the prevention rather than the treatment of cardiological channelopathies.

Obesity-related prepartal insulin resistance in dairy cows is associated with increased lipin 1 and decreased FATP 1 expression in skeletal muscle.

A number of alterations have been identified in lipid metabolism within adipose tissue and liver in obesity. Less is known about the capacity of skeletal muscle for the metabolism of fatty acids in obesity-related insulin resistance, though it is evident that dry cow muscles may contain increased triglyceride content. The current study was therefore undertaken to evaluate the skeletal muscle expression of proteins of the fatty acid metabolism in dry cows with different body condition scores (BCS). Sixteen Holstein-Friesian close-up cows were divided into 2 equal groups based on their BCS as optimal (3.25 ≤ BCS ≤ 3.5) and high (4.0 ≤ BCS ≤ 4.25). Blood samples collection and skeletal muscle biopsies were carried out at day 10 before calving. Blood serum was assayed for concentration of resistin using a bovine specific ELISA. Protein expression of insulin receptor beta subunit (IRß), glucose transporter 4 (GLUT4), fatty acid translocase (FAT/CD36), fatty acid transporter 1 (FATP1), carnitine palmitoyltransferase 1 (CPT1), AMP-acitvated protein kinase (AMPK) and lipin 1 were analyzed in semitendinosus muscle by immunoblot. Resistin differed non-significantly between high-BCS and optimal-BCS cows. Insulin-resistant lipid metabolism in obese cows was paralleled with increased skeletal muscle expression of lipin 1 and GLUT4, and decreased expression of IRß and FATP1. These data suggest that in obesity-related insulin resistance, metabolic capacity in dry cow skeletal muscles appears to be organized towards the synthesis of signaling intermediates rather than fatty acids oxidation and that altered fatty acid uptake does not contribute to this disposition.

It's not "all in your head": critical knowledge gaps on internalized HIV stigma and a call for integrating social and structural conceptualizations.

BACKGROUND: Internalized HIV stigma is a public health concern as it can compromise HIV prevention, care and treatment. This paper has two aims. First, it highlights the urgent need for research evidence on internalized HIV stigma based on critical knowledge gaps. Here, critical knowledge gaps were identified based on most up-to-date systematic review-level evidence on internalized stigma related to HIV and mental health difficulties. Secondly, the paper calls for a shift in focus of internalized HIV stigma research, one that moves beyond psychological frameworks to integrate social, structural and intersectional conceptualizations of stigma. This part of the paper reviews the evolution of stigma theory since Goffman's 1963 seminal work - which defined stigma - to present. MAIN TEXT: Despite studies consistently suggesting that internalized HIV stigma is more prevalent than enacted stigma, there is little evidence of well-established programs to address it. In addition to this, considerable gaps in basic knowledge about the drivers of internalized HIV stigma hamper the development of an evidence-based response to the problem. The limited intervention and epidemiological research on the topic treats internalized HIV stigma as a purely psychological phenomenon. The second part of the paper provides arguments for studying internalized HIV stigma as a function of social and structural forces: (1) Individual-level interventions for internalized HIV stigma are rooted in out-dated theoretical assumptions; (2) From an ethics point of view, it could be argued that individual-level interventions rely on a victim-centric approach to a public health problem; (3) Social and structural approaches to internalized HIV stigma must be explored due to the high opportunity cost associated with small-scale individual-level interventions. CONCLUSIONS: Critical gaps in intervention and epidemiological research in internalized HIV stigma remain. There has been an absence of a shared, sound theoretical understanding of internalized HIV stigma as a manifestation of social and structural factors. This commentary sought to stimulate a dialogue to remedy this absence. Future research should take into account ethical considerations, the evolution of stigma theory over the past five decades, intersectionality and opportunity cost when framing hypotheses, developing theories of change and designing interventions.

Power to participants: a call for person-centred HIV prevention services and research.

INTRODUCTION: While biomedical HIV prevention offers promise for preventing new HIV infections, access to and uptake of these technologies remain unacceptably low in some settings. New models for delivery of HIV prevention are clearly needed. This commentary highlights the potential of person-centred programming and research for increasing the cultural relevance, applicability and use of efficacious HIV prevention strategies. It calls for a shift in perspective within HIV prevention programmes and research, whereby people are recognized for their agency rather than assumed to be passive beneficiaries or research participants. DISCUSSION: Person-centred HIV prevention reorientates power dynamics so that individuals (rather than interventions) are at the centre of the response. Respecting personal choice and agency - and understanding how these are shaped by the context in which people exercise these choices - are critical dimensions of the person-centred approach. Community-based participatory research should be employed to inform and evaluate person-centred HIV prevention. We argue that community-based participatory research is an orientation rather than a method, meaning that it can be integrated within a range of research methods including randomized controlled trials. But embracing community-based participatory approaches in HIV prevention research requires a systemic shift in how this type of research is reported in high impact journals and in how research impact is conceived. Community-based organizations have a critical role to play in both person-centred HIV prevention and research. CONCLUSIONS: HIV prevention is situated at the intersection of unprecedented opportunity and crisis. Person-centred approaches to HIV prevention and research shift power dynamics, and have the potential to ensure a more sustainable response with each individual actively participating in their own care and meaningfully contributing to the production of knowledge on HIV prevention. This approach taps into the resourcefulness, resilience and knowledge of the person and their communities, to strengthen research and programmes, making them more relevant, appropriate and effective.

STACKing the odds for adolescent survival: health service factors associated with full retention in care and adherence amongst adolescents living with HIV in South Africa.

INTRODUCTION: There are two million HIV-positive adolescents in southern Africa, and this group has low retention in care and high mortality. There is almost no evidence to identify which healthcare factors can improve adolescent self-reported retention. This study examines factors associated with retention amongst antiretroviral therapy (ART)-initiated adolescents in South Africa. METHODS: We collected clinical records and detailed standardized interviews (n = 1059) with all 10- to 19 year-olds ever initiated on ART in all 53 government clinics of a health subdistrict, and community traced to include lost-to-follow-up (90.1% of eligible adolescents interviewed). Associations between full self-reported retention in care (no past-year missed appointments and 85% past-week adherence) and health service factors were tested simultaneously in sequential multivariate regression and marginal effects modelling, controlling for covariates of age, gender, urban/rural location, formal/informal housing, maternal and paternal orphanhood, vertical/horizontal HIV infection, overall health, length of time on ART and type of healthcare facility. RESULTS: About 56% of adolescents had self-reported retention in care, validated against lower detectable viral load (AOR: 0.63, CI: 0.45 to 0.87, p = 0.005). Independent of covariates, five factors (STACK) were associated with improved retention: clinics Stocked with medication (OR: 3.0, CI: 1.6 to 5.5); staff with Time for adolescents (OR: 2.7, CI: 1.8 to 4.1); adolescents Accompanied to the clinic (OR: 2.3, CI: 1.5 to 3.6); enough Cash to get to clinic safely (OR: 1.4, CI: 1.1 to 1.9); and staff who are Kind (OR: 2.6, CI: 1.8 to 3.6). With none of these factors, 3.3% of adolescents reported retention. With all five factors, 69.5% reported retention. CONCLUSIONS: This study identifies key intervention points for adolescent retention in HIV care. A basic package of clinic and community services has the potential to STACK the odds for health and survival for HIV-positive adolescents.

Effect of Peroral Administration of Chromium on Insulin Signaling Pathway in Skeletal Muscle Tissue of Holstein Calves.

The objective of this study was to investigate the effects of peroral administration of chromium-enriched yeast on glucose tolerance in Holstein calves, assessed by insulin signaling pathway molecule determination and intravenous glucose tolerance test (IVGTT). Twenty-four Holstein calves, aged 1 month, were chosen for the study and divided into two groups: the PoCr group (n = 12) that perorally received 0.04 mg of Cr/kg of body mass daily, for 70 days, and the NCr group (n = 12) that received no chromium supplementation. Skeletal tissue samples from each calf were obtained on day 0 and day 70 of the experiment. Chromium supplementation increased protein content of the insulin ß-subunit receptor, phosphorylation of insulin receptor substrate 1 at Tyrosine 632, phosphorylation of Akt at Serine 473, glucose transporter-4, and AMP-activated protein kinase in skeletal muscle tissue, while phosphorylation of insulin receptor substrate 1 at Serine 307 was not affected by chromium treatment. Results obtained during IVGTT, which was conducted on days 0, 30, 50, and 70, suggested an increased insulin sensitivity and, consequently, a better utilization of glucose in the PoCr group. Lower basal concentrations of glucose and insulin in the PoCr group on days 30 and 70 were also obtained. Our results indicate that chromium supplementation improves glucose utilization in calves by enhancing insulin intracellular signaling in the skeletal muscle tissue.

Low intensity exercise prevents disturbances in rat cardiac insulin signaling and endothelial nitric oxide synthase induced by high fructose diet.

Increase in fructose consumption together with decrease in physical activity contributes to the development of metabolic syndrome and consequently cardiovascular diseases. The current study examined the preventive role of exercise on defects in cardiac insulin signaling and function of endothelial nitric oxide synthase (eNOS) in fructose fed rats. Male Wistar rats were divided into control, sedentary fructose (received 10% fructose for 9 weeks) and exercise fructose (additionally exposed to low intensity exercise) groups. Concentration of triglycerides, glucose, insulin and visceral adipose tissue weight were determined to estimate metabolic syndrome development. Expression and/or phosphorylation of cardiac insulin receptor (IR), insulin receptor substrate 1 (IRS1), tyrosine-specific protein phosphatase 1B (PTP1B), Akt, extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and eNOS were evaluated. Fructose overload increased visceral adipose tissue, insulin concentration and homeostasis model assessment index. Exercise managed to decrease visceral adiposity and insulin level and to increase insulin sensitivity. Fructose diet increased level of cardiac PTP1B and pIRS1 (Ser307), while levels of IR and ERK1/2, as well as pIRS1 (Tyr 632), pAkt (Ser473, Thr308) and pERK1/2 were decreased. These disturbances were accompanied by reduced phosphorylation of eNOS at Ser1177. Exercise managed to prevent most of the disturbances in insulin signaling caused by fructose diet (except phosphorylation of IRS1 at Tyr 632 and phosphorylation and protein expression of ERK1/2) and consequently restored function of eNOS. Low intensity exercise could be considered as efficient treatment of cardiac insulin resistance induced by fructose diet.