Cholesterol Influences Voltage-Gated Calcium Channels and BK-Type Potassium Channels in Auditory Hair Cells

The influence of membrane cholesterol content on a variety of ion channel conductances in numerous cell models has been shown, but studies exploring its role in auditory hair cell physiology are scarce. Recent evidence shows that cholesterol depletion affects outer hair cell electromotility and the voltage-gated potassium currents underlying tall hair cell development, but the effects of cholesterol on the major ionic currents governing auditory hair cell excitabilityare unknown. We investigated the effects of a cholesterol-depleting agent (methyl beta cyclodextrin, MβCD) on ion channels necessary for the early stages of sound processing. Large-conductance BK-type potassium channels underlie temporal processing and open in a voltage- and calcium-dependent manner. Voltage-gated calcium channels (VGCCs) are responsible for calcium-dependent exocytosis and synaptic transmission to the auditory nerve. Our results demonstrate that cholesterol depletion reduced peak steady-state calcium-sensitive (BK-type) potassiumcurrent by 50% in chick cochlear hair cells. In contrast, MβCD treatment increased peak inward calcium current (∼30%), ruling out loss of calcium channel expression or function as a cause of reduced calcium-sensitive outward current. Changes in maximal conductance indicated a direct impact of cholesterol on channel number or unitary conductance. Immunoblotting following sucrose-gradient ultracentrifugation revealed BK expression in cholesterol-enriched microdomains. Both direct impacts of cholesterol on channel biophysics, as well as channel localization in the membrane, may contribute to the influence of cholesterol on hair cell physiology. Our results reveal a new role for cholesterol in the regulation of auditory calcium and calcium-activated potassium channels and add to the growing evidence that cholesterol is a key determinant in auditory physiology

Characterisation of a functional rat hepatocyte spheroid model.

Many in vitro liver cell models, such as 2D systems, that are used to assess the hepatotoxic potential of xenobiotics suffer major limitations arising from a lack of preservation of physiological phenotype and metabolic competence. To circumvent some of these limitations there has been increased focus on producing more representative 3D models. Here we have used a novel approach to construct a size-controllable 3D hepatic spheroid model using freshly isolated primary rat hepatocytes (PRH) utilising the liquid-overlay technique whereby PRH spontaneously self-assemble in to 3D microtissues. This system produces viable spheroids with a compact in vivo-like structure for up to 21 days with sustained albumin production for the duration of the culture period. F-actin was seen throughout the spheroid body and P-glycoprotein (P-gp) and multidrug resistance-associated protein 2 (MRP2) transporters had polarised expression on the canalicular membrane of hepatocytes within the spheroids upon formation (day 3). The MRP2 transporter was able to functionally transport 5 μM 5-chloromethylfluorescein diacetate (CMFDA) substrates into these canalicular structures. These PRH spheroids display in vivo characteristics including direct cell-cell contacts, cellular polarisation, 3D cellular morphology, and formation of functional secondary structures throughout the spheroid. Such a well-characterised system could be readily exploited for pre-clinical and non-clinical repeat-dose investigations and could make a significant contribution to replace, reduce and refine the use of animals for applied research

Community based distribution of oral HIV self-testing kits in Zambia: a cluster-randomised trial nested in four HPTN 071 (PopART) intervention communities

Background The HPTN 071 (PopART) cluster-randomised trial provided door-to-door HIV testing services to a large proportion of individuals residing in 21 intervention communities in Zambia and South Africa from 2014 to 2017 and reached the UNAIDS first 90 target among women in Zambia, yet gaps remained among men and young adults. This cluster-randomised study nested in the HPTN 071 (PopART) trial sought to increase knowledge of HIV status across all groups by offering the choice of oral HIV self-testing in addition to routine door-to-door HIV testing services. Methods We nested this cluster-randomised trial in four HTPN 071 (PopART) intervention communities in northern Zambia. 66 zones (clusters) in these communities were randomly allocated (1:1) to either oral HIV self-testing plus routine door-to-door HIV testing services (HIV self-testing group) or the PopART standard of care of door-to-door HIV testing services alone (non- HIV self-testing group) over a 3-month period. All individuals aged 16 years or older were eligible for HIV testing. Randomisation was achieved by randomly selecting one allocation from a list of 10 000 possible allocations during a public ceremony. In HIV self-testing zones, trained lay-counsellors (known as community HIV care providers) visited households and offered eligible individuals the choice of HIV testing using HIV self-testing or routine door-to-door HIV testing services. For individuals aged 18 years or older whose partner was absent during the household visit, an HIV self-test kit could be left for secondary distribution to the absent partner. The primary outcome was knowledge of HIV status (defined as self-reporting HIV positive to the community HIV care providers or accepting an offer of HIV testing services). Outcomes were measured among households that were first visited, and individuals first enumerated as a household member during the HIV self-testing intervention period. We analysed data at the individual level using population-average logistic regression models, accounting for clustering of outcomes by zone, to estimate the effect of the intervention. This trial is registered with ClinicalTrials.gov, number NCT02994329. Findings Between Feb 1, and April 30, 2017, the community HIV care providers enumerated 13 267 eligible individuals in the HIV self-testing group and 13 706 in the non-HIV self-testing group. After intervention implementation, 9027 (68%) of 13 267 in the HIV self-testing group had knowledge of HIV status compared with 8952 (65%) of 13 706 in the non-HIV self-testing group (adjusted odds ratio 1·30, 95% CI 1·03–1·65; p=0·03). The effect differed by sex (pinteraction=0·01). Among men, knowledge of HIV status was higher in the HIV self-testing group than in the non-HIV self-testing group (3843 [60%] of 6368 vs 3571 [55%] of 6486; adjusted odds ratio 1·31, 95% CI 1·07–1·60; p=0·01). There was no evidence of a between-group difference among female participants. Interpretation Providing a choice of HIV self-testing during delivery of door-to-door HIV testing services increased knowledge of HIV status, driven by an effect among men. Lay counsellors have a vital role to play in adapting HIV self-testing interventions to local context

Projected outcomes of universal testing and treatment in a generalised HIV epidemic in Zambia and South Africa (the HPTN 071 [PopART] trial): a modelling study

Background The long-term impact of universal home-based testing and treatment as part of universal testing and treatment (UTT) on HIV incidence is unknown. We made projections using a detailed individual-based model of the effect of the intervention delivered in the HPTN 071 (PopART) cluster-randomised trial. Methods In this modelling study, we fitted an individual-based model to the HIV epidemic and HIV care cascade in 21 high prevalence communities in Zambia and South Africa that were part of the PopART cluster-randomised trial (intervention period Nov 1, 2013, to Dec 31, 2017). The model represents coverage of home-based testing and counselling by age and sex, delivered as part of the trial, antiretroviral therapy (ART) uptake, and any changes in national guidelines on ART eligibility. In PopART, communities were randomly assigned to one of three arms: arm A received the full PopART intervention for all individuals who tested positive for HIV, arm B received the intervention with ART provided in accordance with national guidelines, and arm C received standard of care. We fitted the model to trial data twice using Approximate Bayesian Computation, once before data unblinding and then again after data unblinding. We compared projections of intervention impact with observed effects, and for four different scenarios of UTT up to Jan 1, 2030 in the study communities. Findings Compared with standard of care, a 51% (95% credible interval 40–60) reduction in HIV incidence is projected if the trial intervention (arms A and B combined) is continued from 2020 to 2030, over and above a declining trend in HIV incidence under standard of care. Interpretation A widespread and continued commitment to UTT via home-based testing and counselling can have a substantial effect on HIV incidence in high prevalence communities. Funding National Institute of Allergy and Infectious Diseases, US President's Emergency Plan for AIDS Relief, International Initiative for Impact Evaluation, Bill & Melinda Gates Foundation, National Institute on Drug Abuse, and National Institute of Mental Health

Long-chain PUFA supplementation in rural African infants: a randomized controlled trial of effects on gut integrity, growth, and cognitive development.

BACKGROUND: Intestinal damage and malabsorption caused by chronic environmental enteropathy are associated with growth faltering seen in infants in less-developed countries. Evidence has suggested that supplementary omega-3 (n-3) long-chain PUFAs (LC-PUFAs) might ameliorate this damage by reducing gastrointestinal inflammation. LC-PUFA supplementation may also benefit cognitive development. OBJECTIVE: We tested whether early n-3 LC-PUFA supplementation improves infant intestinal integrity, growth, and cognitive function. DESIGN: A randomized, double-blind, controlled trial [200 mg DHA and 300 mg EPA or 2 mL olive oil/d for 6 mo] was conducted in a population of 172 rural Gambian infants aged 3-9 mo. The primary endpoints were anthropometric measures and gut integrity [assessed by using urinary lactulose:mannitol ratios (LMRs)]. Plasma fatty acid status, intestinal mucosal inflammation (fecal calprotectin), daily morbidity, and cognitive development (2-step means-end test and an attention assessment) were secondary endpoints. RESULTS: PUFA supplementation resulted in a significant increase in plasma n-3 LC-PUFA concentrations (P < 0.001 for both DHA and EPA) and midupper arm circumference (MUAC) (effect size: 0.31 z scores; 95% CI: 0.06, 0.56; P = 0.017) at 9 mo of age. At 12 mo, MUAC remained greater in the intervention group, and we observed significant increases in skinfold thicknesses (P ≤ 0.022 for all). No other significant differences between treatment groups were detected for growth or LMRs at 9 mo or for secondary outcomes. CONCLUSIONS: Fish-oil supplementation successfully increased plasma n-3 fatty acid status. However, in young, breastfed Gambian infants, the intervention failed to improve linear growth, intestinal integrity, morbidity, or selected measures of cognitive development. The trial was registered at www.isrctn.org as ISRCTN66645725