Estimated glomerular filtration rate slopes on tenofovir alafenamide

OBJECTIVES

The aim of the study was to analyse and compare estimated glomerular filtration rate (eGFR) slopes during exposure to tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) in individuals who initiated TAF, regardless of prior regimen, before October 2016.

METHODS

An observational cohort study was conducted at 11 clinics in the UK and Ireland. Mixed effects models with random intercept and time terms fitted were used to generate and compare eGFR slopes while participants were exposed to TDF and TAF, with adjustment for age, eGFR at TDF/TAF initiation, gender, ethnicity, and time-updated CD4 cell count and HIV RNA measurements.

RESULTS

Data were available for 357 subjects (median age 50 years; 80% male; 82% white/other ethnicity; 51% men who have sex with men; median nadir CD4 count 216 cells/µL). The median duration of exposure to TAF was 2.0 (interquartile range 1.6, 2.3) years. At TAF initiation, the median CD4 count was 557 cells/µL, the median eGFR was 80 mL/min/1.73 m², and 86% had suppressed HIV infection. The mean adjusted eGFR slope during TDF and TAF exposure was -2.08 [95% confidence interval (CI) -2.24, -1.92] and 1.18 (95% CI 0.20, 1.52) mL/min/1.73 m²/year, respectively (P < 0.001). Individuals who experienced rapid eGFR decline (> 3 or 5 mL/min/1.73 m²/year) while receiving TDF experienced significant eGFR recovery while on TAF (P < 0.001).

CONCLUSIONS

Significant improvement in eGFR slope was observed in patients who switched from TDF- to TAF-containing antiretroviral regimens. These data provide further support for the renal safety of TAF, and for switching those who experience progressive worsening of renal function from TDF to TAF.

Early safety of tenofovir alafenamide in patients with a history of tubulopathy on tenofovir disoproxil fumarate: a randomized controlled clinical trial

OBJECTIVES

The aim of the study was to assess the effect of tenofovir alafenamide (TAF) on kidney and bone biomarkers in patients who developed proximal renal tubulopathy (PRT) while receiving tenofovir disoproxil fumarate (TDF).

METHODS

Individuals with a history of TDF-associated PRT and currently suppressed HIV infection on a tenofovir-sparing regimen were randomized 1:1 to continue current antiretroviral therapy or initiate emtricitabine (F)/TAF with discontinuation of nucleoside reverse transcriptase inhibitors (NRTIs) as appropriate. Renal and bone biomarkers were analysed at baseline, week 4 and week 12. The primary outcome was the mean difference between study arms in urine retinol-binding protein:creatinine ratio (RBPCR) change from baseline to week 12. Data were analysed using linear regression, with robust standard errors (primary outcome), and repeated measures mixed effects models (secondary outcomes). The trial was registered under European Union Drug Regulating Authorities Clinical Trials Database 2016-003345-29.

RESULTS

We randomized 31 individuals [mean age 52.4 (standard deviation 0.3) years; 97% male; 90% white); all completed the study. At 12 weeks, there was no difference in change in RBPCR (β 19.6; 95% confidence interval -35.3, 74.5; P = 0.47), and no difference in change in estimated glomerular filtration rate (eGFR) (based on creatinine or cystatin C), albuminuria, proteinuria, renal phosphate or urea handling, (fasting) urine osmolality, parathyroid hormone and bone turnover markers in the control versus the F/TAF exposed groups. No cases of PRT were observed.

CONCLUSIONS

In people with a history of proximal renal tubulopathy while on TDF, 12-week exposure to TAF did not adversely affect renal tubular function. These data support continued evaluation of the long-term safety of TAF in this group of patients.

Do enhanced sexual health services meet the needs of men who have sex with men?

Enhanced Sexual Health Services (ESHS) have the potential to widen access to sexual health services for populations in England. This study aimed to identify what provision was commissioned in ESHS for men who have sex with men (MSM). We undertook a web-based survey of Primary Care Trust (PCT) commissioners in the south-east of England, exploring what sexual health services were commissioned for MSM and comparing them with published standards. Fourteen of 17 PCTs (82%) responded. All PCTs identified at least one genitourinary (GU) medicine clinic and 13 identified at least one ESHS commissioned for their population. However no single ESHS provided the full range of essential services for MSM. Testing for Chlamydia (84.6% PCTs) and for HIV (69.2% PCTs) were most commonly provided in ESHS, while only 46% and 62% of PCTs had an ESHS commissioned to provide gonorrhoea testing and hepatitis B/syphilis serology testing respectively. Under two-thirds reported training of staff in the sexual health needs of MSM. ESHS are not commissioned to provide the full range of essential sexual health services for MSM. This needs to be addressed by improving staff training in these services and strengthening care pathways between ESHS and GU medicine clinics.

Are primary care-based sexually transmitted infection services in the UK delivering public health benefit?

Sexual health services in primary care, known in the UK as local enhanced services in sexual health (LESSH), aim to increase access to sexually transmitted infection (STI) screening and treatment. Little is known about the characteristics, quality or public health impact of these services. We identified national standards for service provision, and evaluated LESSH against them using a structure, process and outcome approach. Clinical structure and process standards were generally well met, with the exception of partner notification provision. However, public health and outcome measures were largely unascertainable and often undefined in the standards. If the primary care STI services are to deliver public health benefit, improved outcome measures and data collection are required.

Community HIV testing for men who have sex with men: results of a pilot project and comparison of service users with those testing in genitourinary medicine clinics

Results of a community HIV testing pilot (fasTest) targeting men who have sex with men (MSM) in Brighton are reported and service users are compared with those testing in genitourinary medicine (GUM) clinics. FasTest offers rapid HIV testing in a weekly evening drop-in session staffed by GUM professionals in a community organisation. It was prospectively evaluated from November 2004 to March 2006 using a self-completed paper questionnaire assessing demographics, previous use of GUM, HIV testing history and sexual behaviour. Follow-up through GUM/HIV services was monitored. A simplified questionnaire was completed by MSM accessing the GUM clinic over the same time period. Men were included in the analysis if they identified as gay or bisexual or had recent sex with a man, tested for HIV and received a result. In both the fastest and GUM groups, men reported high rates of unprotected anal sex in the last 3 months. fasTest clients were significantly younger and less likely to test positive for HIV. This difference was independent of age and HIV testing history. There was no difference in rates of recent infection between the two. We conclude that community HIV testing is feasible and reaches the target group of high risk MSM.

Attending an STI Foundation course increases chlamydia testing in primary care, but not HIV testing

Summary:

The Sexually Transmitted Infection Foundation course (STIF) is a recommended training course for UK general practitioners (GPs) and others delivering sexual health services in the community. We assessed the impact of attending the course on testing for HIV and chlamydia. Thirty-one GPs attending Brighton STIF courses were identified and the laboratory database was searched to identify all chlamydia and HIV tests they requested in the three months prior to attending, the first three months after attending and the subsequent three months. Three hundred and eight chlamydia tests were performed precourse, 390 postcourse and 342 in the following three months. This represented a significant increase from baseline to postcourse (P = 0.007), which was lost by three to six months (P = 0.25). The proportion of positives did not change. A total of 98, 111 and 131 HIV tests were performed in the three time periods of which; none were positive. Barriers other than training may need to be overcome to increase HIV testing in primary care.

Current use of antiretroviral treatment

INTRODUCTION

Antiretroviral therapy for HIV infection has transformed it from a terminal illness to a chronic manageable condition. This review summarizes the history of the treatment and explains the current practice in the field, including uses in prevention strategies.

SOURCES OF DATA

National and international guidelines, important publications in peer reviewed literature and recent important conference abstracts.

AREAS OF AGREEMENT

There is a broad agreement on the choice of drug regimens and on the need to treat patients with symptomatic HIV infection and with CD4 cell counts less than 350 cells/mm(3). The need to adapt therapy to individual circumstances is also well accepted, e.g. hepatitis co-infection and pregnancy.

AREAS OF CONTROVERSY

Treatment of acute HIV infection and the optimum time to commence therapy in asymptomatic chronic infection remain controversial. Use of antiretrovirals for prevention, e.g. pre-exposure and post-exposure prophylaxis, is still developing.

GROWING POINTS

This article summarizes the current use of anti-HIV medication and the evidence behind it for the non-specialist.

AREAS TIMELY FOR DEVELOPING RESEARCH

New strategies for using current drugs, the best use of newly available drugs and new uses of antiretroviral drugs, such as in prevention of HIV transmission, are key areas for research. Further research addressing the question of when to start antiretrovirals and assessing their long-term effects is also needed.

Studies on the removal of abnormal prion protein by processes used in the manufacture of human plasma products

BACKGROUND AND OBJECTIVES

To identify if any process steps used in plasma fractionation may have a capability of removing agents of human transmissible spongiform encephalopathy (TSE).

MATERIALS AND METHODS

Sixteen fractionation steps were investigated separately by adding a preparation of hamster adapted scrapie 263K to the starting material at each process step and determining the distribution into resultant fractions of protease-K-resistant (abnormal) prion protein by Western blot analysis.

RESULTS

A number of process operations were found to remove abnormal prion protein to the limit of detection of the assay. These were cold ethanol precipitation of fraction IV (log reduction, LR, >/=3.0) and a depth filtration (LR >/=4.9) in the albumin process; cold ethanol fraction I+III precipitation (LR >/=3.7) and a depth filtration (LR >/=2.8) in the immunoglobulin processes and adsorption with DEAE-Toyopearl 650M ion exchanger (LR >/=3.5) in the fibrinogen process. In addition, a substantial degree of removal of abnormal prion protein was observed across DEAE-Toyopearl 650M ion exchange (LR = 3.1) used in the preparation of factor-VIII concentrate; DEAE-cellulose ion exchange (LR = 3.0) and DEAE-sepharose ion exchange (LR = 3.0) used in the preparation of factor-IX concentrates and S-sepharose ion exchange (LR = 2.9) used in the preparation of thrombin.

CONCLUSIONS

Plasma fractionation processes used in the manufacture of albumin, immunoglobulins, factor-VIII concentrate, factor-IX concentrates, fibrinogen and thrombin all contain steps which may be capable of removing causative agents of human TSEs.

Transmissible Spongiform Encephalopathies. Managing risk in mammalian organs, cells and sera. 15-16 March 1999, San Diego, CA, USA

The aim of this conference was to review the risks posed by potential contamination of biopharmaceutical products with the causal agents of Transmissible Spongiform Encephalopathies (TSEs). These agents have become of particular concern with the BSE epidemic in the UK and with a proposed link between BSE and a new variant form of Creutzfeldt-Jakob disease (nvCJD) which occurs at significantly higher incidence in the UK. The conference particularly focused on the potential for contamination of products derived from human blood, where donors are clinically diagnosed as being infected with either classical CJD or nvCJD. Manufacturing steps, with the potential for the removal of TSE agents, were also discussed, along with the strategies available for demonstrating the effectiveness of such steps. Early diagnosis of TSE infection still represents the most effective strategy for the prevention of TSE contamination of biopharmaceutical products, and progress towards the development of assays with sufficient sensitivity to detect TSE contamination either in the raw start material or in donors was discussed.

Protection by green tea, black tea, and indole-3-carbinol against 2-amino-3-methylimidazo[4,5-f]quinoline-induced DNA adducts and colonic aberrant crypts in the F344 rat

Male F344 rats were exposed for 8 weeks to extracts of green tea (2% w/v) or black tea (1% w/v), or to 0.1% dietary indole-3-carbinol (I3C). In weeks 3 and 4 of the study, rats were given 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) every other day by oral gavage (50 mg/kg body wt) in order to induce aberrant crypt foci (ACF) in the colon. Compared with controls given IQ alone, all three inhibitors reduced the number of total aberrant crypts per colon, and green tea and I3C inhibited significantly the mean number of ACF (P < 0.05). Rats pre-treated with green tea, black tea, or I3C and given a single p.o. injection of 50 mg IQ/kg body wt 24-48 h before sacrifice had reduced levels of IQ-DNA adducts in the liver, and excreted lower amounts of IQ and other promutagens in the urine and feces. Inhibitors also reduced the excretion of IQ-sulfamate in the urine, but increased the relative amounts of IQ-5-O-sulfate and IQ-5-O-glucuronide. Western blotting together with assays for 7-ethoxyresorufin O-deethylase and methoxyresorufin O-demethylase established that I3C preferentially induced cytochrome P4501A1 over 1A2, consistent with the altered profile of urinary metabolites. However, both teas caused slight induction of cytochrome P4501A2 versus 1A1, which would be predicted to enhance the activation of IQ. Thus, green tea and black tea are likely to protect against IQ-DNA adducts and ACF by mechanisms other than induction of cytochromes P450, such as inhibition of enzymes which activate IQ or the scavenging of reactive intermediates.

A sequence-specific DNA-binding protein recognising a GA-rich element cooperates with Oct-1 at the herpes simplex virus type 1 IE3 promoter

Herpes simplex virus immediate early (IE) gene transcription is regulated via the upstream TAATGARAT motif and involves the recruitment of the ubiquitous octamer-binding protein Oct-1 and a component of the virion Vmw65 into a multiprotein complex termed the immediate early complex (IEC). An upstream GA-rich element (GA-RE) has been postulated to mediate a response to Vmw65 independent of TAATGARAT. We have studied IEC formation in gel shift assays using DNA fragments containing these sequence elements from the HSV-1 IE gene 3 promoter in different combinations. The results show that a factor which footprints to the GA-RE cooperates with Oct-1 to increase IEC levels on a TAATGARAT motif located 5 bp 5' to the GA-RE. The factor alone is unable to promote IEC formation. We were unable to demonstrate any effect of this factor on a TAATGARAT motif located 16 bp from the GA-RE, suggesting that this effect is not universal for all TAATGARAT motifs.

Temperature dependence of high-affinity CCK receptor binding and CCK internalization in rat pancreatic acini

125I-labeled cholecystokinin (CCK) binding and internalization were studied as a function of temperature in isolated rat pancreatic acini. At 37 degrees C, acini readily bound and degraded 125I-CCK. When labeled hormone binding was inhibited by increasing amounts of unlabeled CCK, competition-inhibition curves were biphasic, consistent with both high- (Kd, 18 pM) and low-affinity (Kd, 13 nM) binding sites. At 4 degrees C, acini bound only one-third as much 125I-CCK and degradation was essentially abolished. At 4 degrees C, CCK competition curves were consistent with a single class of low-affinity binding sites (Kd, 19 nM). Internalization of 125I-CCK was evaluated by three washing procedures utilizing acid, base, and trypsin. All were shown to remove membrane-bound 125I-CCK, and this finding was validated for trypsin by electron microscope autoradiography. After 1 h at 37 degrees C, washing showed 67% of bound 125I-CCK to be internalized and autoradiography showed 54% to be internalized. At 4 degrees C, internalization of bound CCK was greatly reduced but not abolished. When internalization of 125I-CCK was evaluated as a function of the medium concentration of CCK, both high- and low-affinity components were observed. These results suggest that high-affinity CCK binding and CCK internalization are separate temperature-sensitive processes. Moreover, internalization is not uniquely associated with high-affinity binding.

Methylamine and monensin do not block insulin internalization but do influence the intracellular distribution and action of insulin in pancreatic acini from diabetic mice

Methylamine and monensin are two agents known to interfere with the recycling of membrane receptors. In the present investigation, we studied their effects on the binding, intracellular distribution, and action of insulin in isolated pancreatic acini prepared from diabetic mice. These drugs had several similar effects on these cells. In a dose-dependent fashion, both increased the amount of [125I]insulin associated with acini. Methylamine approximately doubled and monensin tripled the amount of insulin associated with cells. Employing electron microscope autoradiographs, we observed the accumulation of hormone in large vacuoles in the Golgi-lysosomal area after treatment with methylamine and in smaller swollen Golgi vesicles after treatment with monensin. The influences of both agents on the biological effects of insulin in acini were then investigated. Both agents blocked insulin stimulation of [3H]2-deoxy-D-glucose uptake in acini. The effect of methylamine was also studied on [3H]leucine incorporation into protein and was found to only partially block the effect of insulin. Since insulin and its receptor are internalized, it is likely that the accumulation of insulin in acini induced by these two agents was due to their inhibition of the cellular processing of insulin and its receptor. Moreover, the effects of these two agents to inhibit insulin-stimulated glucose transport may have resulted from either the inhibition of the recruitment of glucose carriers from the Golgi to the plasma membrane or an abnormal interaction of internalized insulin with the Golgi.

Degradation of insulin by isolated mouse pancreatic acini. Evidence for cell surface protease activity

In the present study, we have used isolated mouse pancreatic acini to investigate the relationship between 125I-insulin binding and its degradation in order to probe the nature and cellular localization of the degradative process. In these cells, the proteolysis of 125I-insulin was dependent on time and cell concentration, and was saturated by unlabeled insulin with a Km of 290 nM. Since this value was much higher than the Kd for insulin binding to its receptor (1.1 nM), the data indicated that 125I-insulin degradation by acini occurred primarily via nonreceptor mechanisms. Several lines of evidence suggested that insulin was being degraded by the neutral thiol protease, insulin degrading enzyme (IDE). First, insulin degradation was inhibited by thiolreacting agents such as N-ethylmaleimide and p-chloromercuribenzoate. Second, the Km for degradation in acini was similar to the reported Km for IDE in other tissues. Third, the enzyme activity had a relative mol wt of approximately 130,000 by gel filtration, a value similar to that reported for purified IDE. Fourth, the degrading activity was removed with a specific antibody to IDE. Other lines of evidence suggested that enzymes located on the cell surface played a role in insulin degradation by acini. First, the nonpenetrating sulfhydryl reacting agent 5,5' dithiobis-2-nitrobenzoic acid blocked 125I-insulin degradation. Second, a specific antibody to IDE identified the presence of the enzyme on the cell surface. Third, chloroquine, leupeptin and antipain, agents that inhibit lysosomal function, did not influence 125I-insulin degradation. Fourth, highly purified pancreatic plasma membranes degraded 125I-insulin.

Insulin regulation of sugar transport in isolated pancreatic acini from diabetic mice

Insulin-stimulated sugar transport was studied in isolated pancreatic acini prepared from streptozotocintreated mice. In this tissue, insulin increased the uptake of two nonmetabolized D-glucose analogues, [3H] 2-deoxy-D-glucose (2DG), and [3H]3-O-methyl-D-glucose (30MG), but had no effect on the uptake of [3H] L-glucose. A significant effect of insulin on 2DG uptake was seen at 100 pM, whereas a maximal effect required a concentration of 100 nM. The action of insulin on 2DG uptake was time-dependent; 90 min was required for a maximal hormonal effect. This increase in 2DG uptake was due to a greater than twofold increase in the maximal rate of uptake (Vmax); no significant effects were seen on Km.

The mode of insulin action on sugar transport was investigated further. In pancreatic acinar cells, insulin did not alter either membrane potential or 45Ca2+ efflux, two proposed mechanisms for regulation of sugar transport in other tissues. The action of insulin was not due to either contamination with cholecystokinin (CCK) or an action via the CCK receptor. CCK is known to stimulate sugar transport in isolated pancreatic acini via the elevation of intracellular Ca2+. The effect of insulin on 2DG uptake, however, was additive to that of CCK; conversely, dibutyryl cyclic GMP, a known competitive antagonist of CCK, had no effect on insulin stimulation of 2DG uptake, insulin increased 2DG uptake in the presence of 10 μM puromycin, a concentration sufficient to inhibit greater than 90% of protein synthesis. Dihydrocytochalasin B, a compound known to alter acinar cell motility by disrupting microfilaments, progressively blocked insulin stimulation of 2DG uptake over a drug concentrationrange of 1–15 μg/ml These data suggest, therefore,that the time-dependent increase of sugar transport by insulin is unrelated to electrical potential, 45Ca2+ efflux, and new protein synthesis, but may result from a microfilament-related translocation of glucose carrier sites to the plasma membrane.

Regulation of protein synthesis in normal and diabetic rat pancreas by cholecystokinin

The effects of cholecystokinin (CCK) on [3H]leucine incorporation into protein were studied in isolated pancreatic acini from normal and streptozotocin-induced diabetic rats. CCK8, the biologically active C-terminal octapeptide of CCK, increased [3H]leucine incorporation into protein over a concentration range that stimulates digestive enzyme secretion (1 X 10(-11) to 1 X 10(-10) M); at higher concentrations, CCK8 inhibited incorporation. Stimulation of [3H]leucine incorporation was greatest in acini from diabetic rats, intermediate in acini from fed normal rats, and least in acini from fasted rats. The magnitude of inhibition was similar in all acini. A significant stimulatory effect of CCK8 in acini from diabetic rats was detected after 10 min and was maximal after 40 min of incubation. Carbachol mimicked both the stimulatory and inhibitory effects of CCK, whereas the Ca2+ ionophore A23187 mimicked only the inhibitory effects. Insulin also stimulated [3H]leucine incorporation in acini from diabetic rats, and its effects were additive to the stimulatory effect of CCK. The present findings suggest that physiological concentrations of CCK and other pancreatic secretagogues may participate in the regulation of pancreatic protein synthesis.