Effectiveness of BNT162b2 mRNA vaccine third doses and previous infection in protecting against SARS-CoV-2 infections during the Delta and Omicron variant waves; the UK SIREN cohort study September 2021 to February 2022

Third doses of COVID-19 vaccines were widely deployed following the primary vaccine course waning and the emergence of the Omicron-variant. We investigated protection from third-dose vaccines and previous infection against SARS-CoV-2 infection during Delta-variant and Omicron-variant (BA.1 & BA.2) waves in our frequently PCR-tested cohort of healthcare-workers. Relative effectiveness of BNT162b2 third doses and infection-acquired immunity was assessed by comparing the time to PCR-confirmed infection in boosted participants with those with waned dose-2 protection (≥254 days after dose-2), by primary series vaccination type. Follow-up time was divided by dominant circulating variant: Delta 07 September 2021 to 30 November 2021, Omicron 13 December 2021t o 28 February 2022. We used a Cox regression model with adjustment/stratification for demographic characteristics and staff-type. We explored protection associated with vaccination, infection and both. We included 19,614 participants, 29% previously infected. There were 278 primary infections (4 per 10,000 person-days of follow-up) and 85 reinfections (0.8/10,000 person-days) during the Delta period and 2467 primary infections (43/10,000 person-days) and 881 reinfections (33/10,000) during the Omicron period. Relative Vaccine Effectiveness (VE) 0-2 months post-3rd dose (3rd dose) (3-doses BNT162b2) in the previously uninfected cohort against Delta infections was 63% (95% Confidence Interval (CI) 40%-77%) and was lower (35%) against Omicron infection (95% CI 21%-47%). The relative VE of 3rd dose (heterologous BNT162b2) was greater for primary course ChAdOX1 recipients, with VE 0-2 months post-3rd dose over ≥68% higher for both variants. Third-dose protection waned rapidly against Omicron, with no significant difference between two and three BNT162b2 doses observed after 4-months. Previous infection continued to provide additional protection against Omicron (67% (CI 56%-75%) 3-6 months post-infection), but this waned to about 25% after 9-months, approximately three times lower than against Delta. Infection rates surged with Omicron emergence. Third doses of BNT162b2 vaccine provided short-term protection, with rapid waning against Omicron infections. Protection associated with infections incurred before Omicron was markedly diminished against the Omicron wave. Our findings demonstrate the complexity of an evolving pandemic with the potential emergence of immune-escape variants and the importance of continued monitoring.

Free HIV self-test for identification and linkage to care of previously undetected HIV infection in men who have sex with men in England and Wales (SELPHI): an open-label, internet-based, randomised controlled trial

BACKGROUND

High levels of HIV testing in men who have sex with men remain key to reducing the incidence of HIV. We aimed to assess whether the offer of a single, free HIV self-testing kit led to increased HIV diagnoses with linkage to care.

METHODS

SELPHI was an internet-based, open-label, randomised controlled trial that recruited participants via sexual and social networking sites. Eligibility criteria included being a man or trans woman (although trans women are reported separately); being resident in England or Wales, UK; being aged 16 years or older; having had anal intercourse with a man; not having a positive HIV diagnosis; and being willing to provide name, email address, date of birth, and consent to link to national HIV databases. Participants were randomly allocated (3:2) by computer-generated number sequence to receive a free HIV self-test kit (BT group) or to not receive this free kit (nBT group). Online surveys collected data at baseline, 2 weeks after enrolment (BT group only), 3 months after enrolment, and at the end of the study. The primary outcome was confirmed (linked to care) new HIV diagnosis within 3 months of enrolment, analysed by intention to treat. Those assessing the primary outcome were masked to allocation. This study is registered with the ISRCTN Clinical Trials Register, number ISRCTN20312003.

FINDINGS

10 111 participants (6049 in BT group and 4062 in nBT group) enrolled between Feb 16, 2017, and March 1, 2018. The median age of participants was 33 years (IQR 26-44 years); 9000 (89%) participants were White; 8118 (80%) participants were born in the UK; 81 (1%) participants were transgender men; 4706 (47%) participants were university educated; 1537 (15%) participants had never been tested for HIV; and 389 (4%) participants were taking pre-exposure prophylaxis. At enrolment, 7282 (72%) participants reported condomless anal sex with at least one male partner in the previous 3 months. In the BT group, of the 4511 participants for whom HIV testing information was available, 4263 (95%) reported having used the free HIV self-test kit within 3 months.Within 3 months of enrolment there were 19 confirmed new HIV diagnoses (0·31%) in 6049 participants in the BT group and 15 (0·37%) of 4062 in the nBT group (p=0·64).

INTERPRETATION

The offer of a single, free HIV self-test did not lead to increased rates of new HIV diagnoses, which could reflect decreasing HIV incidence rates in the UK. Nonetheless, the offer of a free HIV self-testing kit resulted in high HIV testing rates, indicating that self-testing is an attractive testing option for a large group of men who have sex with men.

FUNDING

UK National Institute for Health and Care Research.

A reference human induced pluripotent stem cell line for large-scale collaborative studies

Human induced pluripotent stem cell (iPSC) lines are a powerful tool for studying development and disease, but the considerable phenotypic variation between lines makes it challenging to replicate key findings and integrate data across research groups. To address this issue, we sub-cloned candidate human iPSC lines and deeply characterized their genetic properties using whole genome sequencing, their genomic stability upon CRISPR-Cas9-based gene editing, and their phenotypic properties including differentiation to commonly used cell types. These studies identified KOLF2.1J as an all-around well-performing iPSC line. We then shared KOLF2.1J with groups around the world who tested its performance in head-to-head comparisons with their own preferred iPSC lines across a diverse range of differentiation protocols and functional assays. On the strength of these findings, we have made KOLF2.1J and its gene-edited derivative clones readily accessible to promote the standardization required for large-scale collaborative science in the stem cell field.

Protection against SARS-CoV-2 after Covid-19 Vaccination and Previous Infection

BACKGROUND

The duration and effectiveness of immunity from infection with and vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are relevant to pandemic policy interventions, including the timing of vaccine boosters.

METHODS

We investigated the duration and effectiveness of immunity in a prospective cohort of asymptomatic health care workers in the United Kingdom who underwent routine polymerase-chain-reaction (PCR) testing. Vaccine effectiveness (≤10 months after the first dose of vaccine) and infection-acquired immunity were assessed by comparing the time to PCR-confirmed infection in vaccinated persons with that in unvaccinated persons, stratified according to previous infection status. We used a Cox regression model with adjustment for previous SARS-CoV-2 infection status, vaccine type and dosing interval, demographic characteristics, and workplace exposure to SARS-CoV-2.

RESULTS

Of 35,768 participants, 27% (9488) had a previous SARS-CoV-2 infection. Vaccine coverage was high: 95% of the participants had received two doses (78% had received BNT162b2 vaccine [Pfizer-BioNTech] with a long interval between doses, 9% BNT162b2 vaccine with a short interval between doses, and 8% ChAdOx1 nCoV-19 vaccine [AstraZeneca]). Between December 7, 2020, and September 21, 2021, a total of 2747 primary infections and 210 reinfections were observed. Among previously uninfected participants who received long-interval BNT162b2 vaccine, adjusted vaccine effectiveness decreased from 85% (95% confidence interval [CI], 72 to 92) 14 to 73 days after the second dose to 51% (95% CI, 22 to 69) at a median of 201 days (interquartile range, 197 to 205) after the second dose; this effectiveness did not differ significantly between the long-interval and short-interval BNT162b2 vaccine recipients. At 14 to 73 days after the second dose, adjusted vaccine effectiveness among ChAdOx1 nCoV-19 vaccine recipients was 58% (95% CI, 23 to 77) - considerably lower than that among BNT162b2 vaccine recipients. Infection-acquired immunity waned after 1 year in unvaccinated participants but remained consistently higher than 90% in those who were subsequently vaccinated, even in persons infected more than 18 months previously.

CONCLUSIONS

Two doses of BNT162b2 vaccine were associated with high short-term protection against SARS-CoV-2 infection; this protection waned considerably after 6 months. Infection-acquired immunity boosted with vaccination remained high more than 1 year after infection. (Funded by the U.K. Health Security Agency and others; ISRCTN Registry number, ISRCTN11041050.).

Tuberculosis incidence in country of origin is a key determinant of the risk of active tuberculosis in people living with HIV: Data from a 30-year observational cohort study

INTRODUCTION

People living with HIV (PLWH) are at high risk of active tuberculosis (TB) but this risk in the era of antiretroviral treatment (ART) remains unclear. It is critical to identify the groups who should be prioritised for latent TB (LTBI) screening. In this study we identified the risk factors associated with developing incident TB disease, by analysing a 30-year observational cohort.

METHODS

We evaluated PLWH in Leicester, UK, between 1983 and 2017 to ascertain those who developed active TB and the timing of this in relation to HIV diagnosis; whether before, concurrently with, or more than 3 months after the diagnosis of HIV (incident TB). Predictors of incident TB were ascertained using Cox proportional hazards models.

RESULTS

In all, 325 out of 2158 (15.1%) PLWH under care had had active TB; 64/325 (19.7%) prior to HIV diagnosis, 161/325 (49.5%) concurrently with/within 3 months of HIV diagnosis and 100/325 (30.8%) had incident TB. Incident TB risk was 4.57/1000 person-years. Increased TB incidence in the country of birth was associated with an increased risk of developing incident TB [50-149/100 000 population, adjusted hazard ratio (AHR) = 3.10, 95% CI: 0.94-10.20; 150-249/100 000 population, AHR = 7.14, 95% CI: 3.46-14.74; 250-349/100 000 population, AHR = 5.90, 95% CI: 2.32-14.99; ≥ 350/100 000 population, AHR = 3.96, 95% CI: 1.39-11.26].

CONCLUSIONS

Tuberculosis risk remains high among PLWH and is related to TB incidence in the country of birth. Further work is required to determine whether specific groups of PLWH should be targeted for programmatic LTBI screening, and whether it will result in high uptake and completion of chemoprophylaxis and is cost-effective for widespread implementation.

Linkage of Whole Genome Sequencing, Epidemiological, and Clinical Data to Understand the Genetic Diversity and Clinical Outcomes of Shigella flexneri among Men Who Have Sex with Men in England

The public health value of whole genome sequencing (WGS) for Shigella spp. in England has been limited by a lack of information on sexual identity and behavior. We combined WGS data with other data sources to better understand Shigella flexneri transmission in men who have sex with men (MSM). WGS data for all S. flexneri isolates referred to the national reference laboratory were linked to i) clinical and behavioral data collected in seven of 21 health regions in England using a standardized exposure questionnaire and, ii) national HIV surveillance data. We included 926 S. flexneri isolates, of which 43.0% (n = 398) fell phylogenetically within two domestically circulating clades associated with genotypic markers of azithromycin resistance. Approximately one third of isolates in these clades were from people living with HIV, primarily acquired through sex between men. 182 (19.7%) isolates had linked questionnaire data; 88% (84/95) of MSM isolates fell phylogenetically within the domestically circulating clades, while 92% (72/78) of isolates from other cases fell within lineages linked with travel to high-risk regions. There was no evidence of sustained transmission between networks of MSM and the wider community. MSM were more likely to be admitted to hospital and receive antimicrobials. Our study emphasizes the importance of sex between men as a major route of transmission for S. flexneri. Combined WGS, epidemiological and clinical data provide unique insights that can inform contact tracing, clinical management and the delivery of targeted prevention activities. Future studies should investigate why MSM experience more severe clinical outcomes. IMPORTANCE Within the last 2 decades there have been an increasing number of Shigella spp. outbreaks among men who have sex with men (MSM) worldwide. In 2015, Public Health England (PHE) introduced routine whole genome sequencing (WGS) for the national surveillance of Shigella spp. However, the lack of information on sexual identity and behavior has hindered interpretation. Our study illustrates the power of linking WGS data with epidemiological, behavioral, and clinical data. We provide unique population-level insights into different transmission networks that can inform the delivery of appropriate public health interventions and patient management. Furthermore, we describe and compare clinical characteristics and outcomes of S. flexneri infection in MSM and other exposure groups. We found that MSM were more likely to be admitted to hospital and receive antimicrobials, indicating that their infections were potentially more severe. The exact reasons for this are unclear and require further exploration.

COVID-19 mortality among people with diagnosed HIV compared to those without during the first wave of the COVID-19 pandemic in England

Objectives

We describe COVID‐19 mortality among people with and without HIV during the first wave of the pandemic in England.

Methods

National surveillance data on adults (aged ≥ 15 years) with diagnosed HIV resident in England were linked to national COVID‐19 mortality surveillance data (2 March 2020–16 June 2020); HIV clinicians verified linked cases and provided information on the circumstances of death. We present COVID‐19 mortality rates by HIV status, using negative binomial regression to assess the association between HIV and mortality, adjusting for gender, age and ethnicity.

Results

Overall, 99 people with HIV, including 61 of black ethnicity, died of/with COVID‐19 (107/100 000) compared with 49 483 people without HIV (109/100 000). Compared to people without HIV, higher COVID‐19 mortality rates were observed in people with HIV of black (188 vs. 122/100 000) and Asian (131 vs. 77.0/100 000) ethnicity, and in both younger (15–59 years: 58.3 vs. 10.2/100 000) and older (≥ 60 years: 434 vs. 355/100 000) people. After adjustment for demographic factors, people with HIV had a higher COVID‐19 mortality risk than those without (2.18; 95% CI: 1.76–2.70). Most people with HIV who died of/with COVID‐19 had suppressed HIV viraemia (91%) and at least one comorbidity reported to be associated with poor COVID‐19 outcomes (87%).

Conclusions

In the first wave of the pandemic in England, COVID‐19 mortality among people with HIV was low, but was higher than in those without HIV, after controlling for demographic factors. This supports the strategy of prioritizing COVID‐19 vaccination for people with HIV and strongly encouraging its uptake, especially in those of black and Asian ethnicity.

Tracking elimination of HIV transmission in men who have sex with men in England: a modelling study

BACKGROUND

To manage the HIV epidemic among men who have sex with men (MSM) in England, treatment as prevention strategies based on test and treat were strengthened between 2011 and 2015, and supplemented from 2015 by scale-up of pre-exposure prophylaxis (PrEP). We examined the effect of these interventions on HIV incidence and investigated whether internationally agreed targets for HIV control and elimination of HIV transmission by 2030 might be within reach among MSM in England.

METHODS

We used a novel, age-stratified, CD4-staged Bayesian back-calculation model to estimate HIV incidence and undiagnosed infections among adult MSM (age ≥15 years) during the 10-year period between 2009 and 2018. The model used data on HIV and AIDS diagnoses routinely collected via the national HIV and AIDS Reporting System in England, and knowledge on the progression of HIV through CD4-defined disease stages. Estimated incidence trends were extrapolated, assuming a constant MSM population from 2018 onwards, to quantify the likelihood of achieving elimination of HIV transmission, defined as less than one newly aquired infection per 10 000 MSM per year, by 2030.

FINDINGS

The peak in HIV incidence in MSM in England was estimated with 80% certainty to have occurred in 2012 or 2013, at least 1 year before the observed peak in new diagnoses in 2014. Results indicated a steep decrease in the annual number of new infections among MSM, from 2770 (95% credible interval 2490-3040) in 2013 to 1740 (1500-2010) in 2015, followed by a steadier decrease from 2016, down to 854 (441-1540) infections in 2018. A decline in new infections was consistently estimated in all age groups, and was particularly marked in MSM aged 25-34 years, and slowest in those aged 45 years or older. Similar trends were estimated in the number of undiagnosed infections, with the greatest decrease after 2013 in the 25-34 years age group. Under extrapolation assumptions, we calculated a 40% probability of achieving the defined target elimination threshold by 2030.

INTERPRETATION

The sharp decrease in HIV incidence, estimated to have begun before the scale up of PrEP, indicates the success of strengthening treatment as prevention measures among MSM in England. To achieve the 2030 elimination threshold, targeted policies might be required to reach those aged 45 years or older, in whom incidence is decreasing at the slowest rate.

FUNDING

UK Medical Research Council, UK National Institute of Health Research Health Protection Unit in Behavioural Science and Evaluation, and Public Health England.

Surveillance of HIV-1 transmitted integrase strand transfer inhibitor resistance in the UK

Background

HIV treatment guidelines have traditionally recommended that all HIV-positive individuals are tested for evidence of drug resistance prior to starting ART. Testing for resistance to reverse transcriptase inhibitors and PIs is well established in routine care. However, testing for integrase strand transfer inhibitor (InSTI) resistance is less consistent.

Objectives

To inform treatment guidelines by determining the prevalence of InSTI resistance in a national cohort of recently infected individuals.

Patients and methods

Recent (within 4 months) HIV-1 infections were identified using a Recent Infection Testing Algorithm of new HIV-1 diagnoses in the UK. Resistance-associated mutations (RAMs) in integrase, protease and reverse transcriptase were detected by ultradeep sequencing, which allows for the sensitive estimation of the frequency of each resistant variant in a sample.

Results

The analysis included 655 randomly selected individuals (median age = 33 years, 95% male, 83% MSM, 78% white) sampled in the period 2014 to 2016 and determined to have a recent infection. These comprised 320, 138 and 197 samples from 2014, 2015 and 2016, respectively. None of the samples had major InSTI RAMs occurring at high variant frequency (≥20%). A subset (25/640, 3.9%) had major InSTI RAMs occurring only as low-frequency variants (2%–20%). In contrast, 47/588 (8.0%) had major reverse transcriptase inhibitor and PI RAMs at high frequency.

Conclusions

Between 2014 and 2016, major InSTI RAMs were uncommon in adults with recent HIV-1 infection, only occurring as low-frequency variants of doubtful clinical significance. Continued surveillance of newly diagnosed patients for evidence of transmitted InSTI resistance is recommended to inform clinical practice.

Does being on HIV antiretroviral therapy increase the risk of syphilis? An analysis of a large national cohort of MSM living with HIV in England 2009-2016

OBJECTIVE

A resurgence in bacterial STIs, notably syphilis, among gay, bisexual and other men who have sex with men (MSM) has been detected in England. A Canadian modelling study postulated that antiretroviral therapy (ART) may increase susceptibility to syphilis. We assess the association between ART and syphilis incidence in a comprehensive national cohort of MSM living with HIV in England.

METHODS

National surveillance data were used to create a cohort of MSM attending for both HIV and STI care in England between 2009 and 2016. Survival analysis was used to calculate the incidence of infectious syphilis during periods on and off ART. Multivariable Poisson regression was used to assess the association between ART use and syphilis, after adjustment for potential confounders, including, as a proxy measure for high-risk behaviour, being diagnosed with >1 other STI prior to a syphilis diagnosis.

RESULTS

19 428 HIV diagnosed MSM contributed 112 960 person-years of follow-up from 2009 to 2016. The overall rate of syphilis was 78.0 cases per 1000 person-years follow-up. Syphilis rates were higher among men receiving ART (36.8) compared with those who did not (28.4) (absolute rate difference 4.7 cases per 1000 person-years). Multivariable analysis showed no statistical association between receiving ART and syphilis. Increased risk of syphilis was found in MSM aged 25-34 (HR 1.89, 95% CI 1.43 to 2.51) and in those diagnosed with two other STIs (HR 5.83, 95% CI 5.37 to 6.32).

CONCLUSION

While we observed a small increase in the rate of syphilis among those on ART, when adjusting for potential confounding factors, including a proxy measure for high-risk behaviour, there was no evidence of an increased risk of syphilis in MSM receiving ART. High-risk sexual behaviour markers were the main risk factors for syphilis, and our results highlight the need for STI prevention interventions in MSM living with HIV to target these particularly high-risk sexual networks.

Determining the Origins of Human Immunodeficiency Virus Type 1 Drug-resistant Minority Variants in People Who Are Recently Infected Using Phylogenetic Reconstruction

BACKGROUND

Drug-resistant minority variants (DRMinVs) detected in patients who recently acquired human immunodeficiency virus type 1 (HIV-1) can be transmitted, generated de novo through virus replication, or technical errors. The first form is likely to persist and result in treatment failure, while the latter two could be stochastic and transient.

METHODS

Ultradeep sequencing of plasma samples from 835 individuals with recent HIV-1 infection in the United Kingdom was performed to detect DRMinVs at a mutation frequency between 2% and 20%. Sequence alignments including >110 000 HIV-1 partial pol consensus sequences from the UK HIV Drug Resistance Database (UK-HDRD), linked to epidemiological and clinical data from the HIV and AIDS Reporting System, were used for transmission cluster analysis. Transmission clusters were identified using Cluster Picker with a clade support of >90% and maximum genetic distances of 4.5% or 1.5%, the latter to limit detection to likely direct transmission events.

RESULTS

Drug-resistant majority variants (DRMajVs) were detected in 66 (7.9%) and DRMinVs in 84 (10.1%) of the recently infected individuals. High levels of clustering to sequences in UK-HDRD were observed for both DRMajV (n = 48; 72.7%) and DRMinV (n = 63; 75.0%) sequences. Of these, 43 (65.2%) with DRMajVs were in a transmission cluster with sequences that harbored the same DR mutation compared to only 3 (3.6%) sequences with DRMinVs (P < .00001, Fisher exact test). Evidence of likely direct transmission of DRMajVs was observed for 25/66 (37.9%), whereas none were observed for the DRMinVs (P < .00001).

CONCLUSIONS

Using a densely sampled HIV-infected population, we show no evidence of DRMinV transmission among recently infected individuals.

Human BDNF/TrkB variants impair hippocampal synaptogenesis and associate with neurobehavioural abnormalities

Brain-derived neurotrophic factor (BDNF) signals through its high affinity receptor Tropomyosin receptor kinase-B (TrkB) to regulate neuronal development, synapse formation and plasticity. In rodents, genetic disruption of Bdnf and TrkB leads to weight gain and a spectrum of neurobehavioural phenotypes. Here, we functionally characterised a de novo missense variant in BDNF and seven rare variants in TrkB identified in a large cohort of people with severe, childhood-onset obesity. In cells, the E183K BDNF variant resulted in impaired processing and secretion of the mature peptide. Multiple variants in the kinase domain and one variant in the extracellular domain of TrkB led to a loss of function through multiple signalling pathways, impaired neurite outgrowth and dominantly inhibited glutamatergic synaptogenesis in hippocampal neurons. BDNF/TrkB variant carriers exhibited learning difficulties, impaired memory, hyperactivity, stereotyped and sometimes, maladaptive behaviours. In conclusion, human loss of function BDNF/TrkB variants that impair hippocampal synaptogenesis may contribute to a spectrum of neurobehavioural disorders.

Proopiomelanocortin Processing in the Hypothalamus Is Directly Regulated by Saturated Fat: Implications for the Development of Obesity

In outbred mice, susceptibility or resistance to diet-induced obesity is associated with rapid changes in hypothalamic proopiomelanocortin (POMC) levels. Here, we evaluated 3 hypotheses that potentially explain the development of the different obesity phenotypes in outbred Swiss mice. First, rapid and differential changes in the gut microbiota in obesity-prone (OP) and obesity-resistant (OR) mice fed on a high-fat diet (HFD) might cause differential efficiencies in fatty acid harvesting leading to changes in systemic fatty acid concentrations that in turn affect POMC expression and processing. Second, independently of the gut microbiota, OP mice might have increased blood fatty acid levels after the introduction of a HFD, which could affect POMC expression and processing. Third, fatty acids might act directly in the hypothalamus to differentially regulate POMC expression and/or processing in OP and OR mice. We evaluated OP and OR male Swiss mice using 16S rRNA sequencing for the determination of gut microbiota; gas chromatography for blood lipid determination; and immunoblot and real-time polymerase chain reaction for protein and transcript determination and indirect calorimetry. Some experiments were performed with human pluripotent stem cells differentiated into hypothalamic neurons. We did not find evidence supporting the first 2 hypotheses. However, we found that in OP but not in OR mice, palmitate induces a rapid increase in hypothalamic POMC, which is followed by increased expression of proprotein convertase subtilisin/kexin type 1 PC1/3. Lentiviral inhibition of hypothalamic PC1/3 increased caloric intake and body mass in both OP and OR mice. In human stem cell-derived hypothalamic cells, we found that palmitate potently suppressed the production of POMC-derived peptides. Palmitate directly regulates PC1/3 in OP mice and likely has a functional impact on POMC processing.

Extending Bayesian back-calculation to estimate age and time specific HIV incidence

CD4-based multi-state back-calculation methods are key for monitoring the HIV epidemic, providing estimates of HIV incidence and diagnosis rates by disentangling their inter-related contribution to the observed surveillance data. This paper, extends existing approaches to age-specific settings, permitting the joint estimation of age- and time-specific incidence and diagnosis rates and the derivation of other epidemiological quantities of interest. This allows the identification of specific age-groups at higher risk of infection, which is crucial in directing public health interventions. We investigate, through simulation studies, the suitability of various bivariate splines for the non-parametric modelling of the latent age- and time-specific incidence and illustrate our method on routinely collected data from the HIV epidemic among gay and bisexual men in England and Wales.

HIV care cost in England: a cross-sectional analysis of antiretroviral treatment and the impact of generic introduction

OBJECTIVES

Reliable and timely HIV care cost estimates are important for policy option appraisals of HIV treatment and prevention strategies. As HIV clinical management and outcomes have changed, we aimed to update profiles of antiretroviral (ARV) usage pattern, patent/market exclusivity details and management costs in adults (≥ 18 years old) accessing HIV specialist care in England.

METHODS

The data reported quarterly to the HIV and AIDS Reporting System in England was used to identify ARV usage pattern, and were combined with British National Formulary (BNF) prices, non-ARV care costs and patent/market exclusivity information to generate average survival-adjusted lifetime care costs. The cumulative budget impact from 2018 to the year in which all current ARVs were expected to lose market exclusivity was calculated for a hypothetical 85 000 (± 5000) person cohort, which provided an illustration of potential financial savings afforded by bioequivalent generic switches. Price scenarios explored BNF70 (September 2015) prices and generics at 10/20/30/50% of proprietary prices. The analyses took National Health Service (NHS) England's perspective (as the payer), and results are presented in 2016/2017 British pounds.

RESULTS

By 2033, most currently available ARVs would lose market exclusivity; that is, generics could be available. Average per person lifetime HIV cost was ~£200 000 (3.5% annual discount) or ~£400 000 (undiscounted), reducing to ~£70 000 (3.5% annual discount; ~£120 000 undiscounted) with the use of generics (assuming that generics cost 10% of proprietary prices). The cumulative budget to cover 85 000 (± 5000) persons for 16 years (2018-2033) was £10.5 (± 0.6) billion, reducing to £3.6 (± 0.2) billion with the use of generics.

CONCLUSIONS

HIV management costs are high but financial efficiency could be improved by optimizing generic use for treatment and prevention to mitigate the high cost of lifelong HIV treatment. Earlier implementation of generics as they become available offers the potential to maximize the scale of the financial savings.

Predictive factors for HIV infection among men who have sex with men and who are seeking PrEP: a secondary analysis of the PROUD trial

OBJECTIVES

Pre-exposure prophylaxis (PrEP) is a highly effective method of HIV prevention for men who have sex with men (MSM). However, uncertainty remains around the optimal eligibility criteria for PrEP, specifically whether there are subgroups at low risk of HIV for whom PrEP might not be warranted.

METHODS

PROUD was an open-label waitlist trial design that randomised MSM attending participating sexual health centres in England to receive PrEP immediately (IMM) or after a deferral period of 1 year (DEF). This analysis is based on participants who were randomised to the deferred arm, when they did not have access to PrEP. HIV incidence was compared between subgroups defined by baseline characteristics.

RESULTS

Overall, 21 participants acquired HIV infection over 239.3 person-years (PY) follow-up, yielding an incidence rate of 8.8/100 PY (95% CI 5.4 to 13.4). Two highly significant predictors for HIV acquisition were identified. Men with a self-reported diagnosis of syphilis, rectal chlamydia (CT) or rectal gonorrhoea (GC) in the previous 12 months had an incidence of 17.2/100 PY (95% CI 9.7 to 28.5); those reporting receptive anal intercourse without a condom (ncRAI) with two or more partners in the previous 3 months had an incidence of 13.6/100 PY (95% CI 7.9 to 21.7). The incidence rate among participants lacking both of these risk factors was 1.1/100 PY (1/87.6, 95% CI 0.03 to 6.4).

CONCLUSIONS

The high HIV incidence in PROUD suggests that most participants appropriately judged their need for PrEP. Eligibility criteria for a PrEP programme can therefore be broad, as in the current guidelines. However, a recent history of syphilis or rectal CT/GC, or multiple ncRAI partners indicates a high imminent risk of HIV infection. MSM with any of these characteristics should be offered PrEP as a matter of urgency.

HIV coinfection among persons diagnosed with hepatitis B in England in 2008-2014

OBJECTIVES

The aim of the study was to estimate HIV prevalence among persons with hepatitis B virus (HBV) infection in England and to examine associated risk factors.

METHODS

Persons aged ≥ 15 years with an HBV surface antigen (HBsAg) test reported to Public Health England (PHE) sentinel surveillance during 2008-2014 were linked to the PHE national HIV/AIDS database. Coinfection was defined as an HIV diagnosis prior to, or within 6 months following, a positive HBsAg test.

RESULTS

During 2008-2014, 2 149 933 persons were tested for HBsAg and 3.9% (1129 of 28 789) of HBsAg-positive persons were HIV positive. The probable route of HIV infection was heterosexual exposure for 95.3% of female patients and 32.3% of male patients, with 61.5% of male patients reporting sex between men. Among African-born coinfected persons, 84% probably acquired HIV there. Predictors of HIV positivity included older age [adjusted odds ratio (aOR) 1.1] and being of black ethnicity (aOR 15.5 for males; aOR 16.4 for females) or being male and of white ethnicity (aOR 8.2) compared with being female and of white ethnicity. HIV coinfection was more likely when HBV was diagnosed in sexual health (aOR 55.0), specialist liver (aOR 6.7), emergency department (aOR 5.3) and renal services (aOR 2.8) compared with general practice. Most (60.4%; 682 of 1129) coinfected persons were diagnosed with HIV infection > 6 months before HBV diagnosis.

CONCLUSIONS

Persons testing positive for HBsAg had a low HIV infection rate and fell largely into two groups: those of black ethnicity with probable Africa-acquired infections and white men who have sex with men (MSM) with probable UK-acquired infections. Findings reinforce existing recommendations to sustain and improve both HBV testing of migrants from HBV-prevalent countries and vaccination among HIV-positive MSM. Findings also support blood-borne virus testing in sexual health services and emergency departments.

Quantitative mass spectrometry for human melanocortin peptides in vitro and in vivo suggests prominent roles for β-MSH and desacetyl α-MSH in energy homeostasis

OBJECTIVE

The lack of pro-opiomelanocortin (POMC)-derived melanocortin peptides results in hypoadrenalism and severe obesity in both humans and rodents that is treatable with synthetic melanocortins. However, there are significant differences in POMC processing between humans and rodents, and little is known about the relative physiological importance of POMC products in the human brain. The aim of this study was to determine which POMC-derived peptides are present in the human brain, to establish their relative concentrations, and to test if their production is dynamically regulated.

METHODS

We analysed both fresh post-mortem human hypothalamic tissue and hypothalamic neurons derived from human pluripotent stem cells (hPSCs) using liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine the sequence and quantify the production of hypothalamic neuropeptides, including those derived from POMC.

RESULTS

In both in vitro and in vivo hypothalamic cells, LC-MS/MS revealed the sequence of hundreds of neuropeptides as a resource for the field. Although the existence of β-melanocyte stimulating hormone (MSH) is controversial, we found that both this peptide and desacetyl α-MSH (d-α-MSH) were produced in considerable excess of acetylated α-MSH. In hPSC-derived hypothalamic neurons, these POMC derivatives were appropriately trafficked, secreted, and their production was significantly (P < 0.0001) increased in response to the hormone leptin.

CONCLUSIONS

Our findings challenge the assumed pre-eminence of α-MSH and suggest that in humans, d-α-MSH and β-MSH are likely to be the predominant physiological products acting on melanocortin receptors.

Prevalence of diagnosed HIV infection among persons with hepatitis C virus infection: England, 2008-2014

OBJECTIVES

In persons with hepatitis C virus (HCV) infection, HIV coinfection leads to faster progression to advanced liver disease. The aim of our study was to estimate diagnosed HIV prevalence among people with evidence of current HCV infection (polymerase chain reaction positive) and examine predictors of coinfection.

METHODS

Adults (≥ 15 years old) with a current HCV infection reported to the Public Health England (PHE) sentinel surveillance of blood-borne viruses were linked to the PHE national HIV database using a deterministic methodology. Descriptive and multivariate analyses were conducted.

RESULTS

Between 2008 and 2014, 5.0% (999/20 088) of adults with a current HCV infection were diagnosed with HIV coinfection. The majority acquired HIV through sex between men (441; 64.9%), followed by injecting drug use (153; 22.5%) and heterosexual contact (84; 12.4%). Of persons who were coinfected, 65.5% had been diagnosed with HIV infection > 6 months before their HCV diagnosis, 41.4% of whom had a negative anti-HCV test between their HIV and HCV diagnoses. In a multivariable model among persons with current HCV infection, an HIV diagnosis was more likely among men [adjusted odds ratio (aOR) 3.29; 95% confidence interval (CI) 2.60-4.16] and persons of black ethnicity (aOR 3.19; 95% CI 1.36-7.46), and less likely among older adults (aOR 0.85 per 10-year increase; 95% CI 0.79-0.92) and persons of Asian ethnicity (aOR 0.59; 95% CI 0.41-0.86).

CONCLUSIONS

Our results indicate that the majority of diagnosed HIV and current HCV coinfections are among men who have sex with men. Safer sex campaigns should include awareness of transmission of HCV among MSM living with HIV.

The people living with HIV stigma survey UK 2015: HIV-related sexual rejection and other experiences of stigma and discrimination among gay and heterosexual men

We aim to understand the difference in stigma and discrimination, in particular sexual rejection, experienced between gay and heterosexual men living with HIV in the UK. The People Living with HIV StigmaSurvey UK 2015 recruited a convenience sample of persons with HIV through over 120 cross sector community organisations and 46 HIV clinics to complete an online survey. 1162 men completed the survey, 969 (83%) gay men and 193 (17%) heterosexual men, 92% were on antiretroviral therapy. Compared to heterosexual men, gay men were significantly more likely to report worrying about workplace treatment in relation to their HIV (21% vs. 11%), worrying about HIV-related sexual rejection (42% vs 21%), avoiding sex because of their HIV status (37% vs. 23%), and experiencing HIV-related sexual rejection (27% vs. 9%) in the past 12 months. In a multivariate logistic regression controlling for other sociodemographic factors, being gay was a predictor of reporting HIV-related sexual rejection in the past 12 months (aOR 2.17, CI 1.16, 4.02). Both gay and heterosexual men living with HIV experienced stigma and discrimination in the past 12 months, and this was higher for gay men in terms of HIV-related sexual rejection. Due to the high proportion of men reporting sexual rejection, greater awareness and education of the low risk of transmission of HIV among people on effective treatment is needed to reduce stigma and sexual prejudice towards people living with HIV.

Where do we diagnose HIV infection? Monitoring new diagnoses made in nontraditional settings in England, Wales and Northern Ireland

OBJECTIVES

The objectives of the study were to describe 10-year trends in HIV diagnosis setting and to explore predictors of being diagnosed outside a sexual health clinic (SHC).

METHODS

Analyses of national HIV surveillance data were restricted to adults (aged ≥ 15 years) diagnosed in 2005-2014 in England, Wales and Northern Ireland. Logistic regression identified factors associated with diagnosis outside an SHC (2011-2014).

RESULTS

Between 2005 and 2014, 63 599 adults were newly diagnosed with HIV infection; 83% had a diagnosis setting reported. Most people were diagnosed in SHCs (69%) followed by: medical admissions/accident and emergency (A&E; 8.6%), general practice (6.4%), antenatal services (5.5%), out-patient services (3.6%), infectious disease units (2.7%) and other settings (4.0%). The proportion of people diagnosed outside SHCs increased from 2005 to 2014, overall (from 27% to 32%, respectively) and among men who have sex with men (MSM) (from 14% to 21%) and black African men (from 25% to 37%) and women (from 39% to 52%) (all trend P < 0.001). Median CD4 increased across all settings, but was highest in SHCs (384 cells/μL) and lowest in medical admissions/A&E (94 cells/μL). Predictors of being diagnosed outside SHCs included: acquiring HIV through heterosexual contact [adjusted odds ratio (aOR) 1.99; 95% confidence interval (CI) 1.81-2.18] or injecting drug use (aOR: 3.28; 95% CI: 2.56-4.19; reference: MSM), being diagnosed late (< 350 cells/μL) (aOR: 2.55; 95% CI: 2.36-2.74; reference: diagnosed promptly) and being of older age at diagnosis (35-49 years: aOR: 1.60; 95% CI: 1.39-1.83; ≥ 50 years: aOR: 2.48; 95% CI: 2.13-2.88; reference: 15-24 years).

CONCLUSIONS

The proportion of HIV diagnoses made outside SHCs has increased over the past decade in line with evolving HIV testing guidelines. However, the rate of late diagnosis remains high, indicating that further expansion of testing is necessary, as many people may have had missed opportunities for earlier diagnosis.

Rapid sensing of l-leucine by human and murine hypothalamic neurons: Neurochemical and mechanistic insights

Objective

Dietary proteins are sensed by hypothalamic neurons and strongly influence multiple aspects of metabolic health, including appetite, weight gain, and adiposity. However, little is known about the mechanisms by which hypothalamic neural circuits controlling behavior and metabolism sense protein availability. The aim of this study is to characterize how neurons from the mediobasal hypothalamus respond to a signal of protein availability: the amino acid l-leucine.

Methods

We used primary cultures of post-weaning murine mediobasal hypothalamic neurons, hypothalamic neurons derived from human induced pluripotent stem cells, and calcium imaging to characterize rapid neuronal responses to physiological changes in extracellular l-Leucine concentration.

Results

A neurochemically diverse subset of both mouse and human hypothalamic neurons responded rapidly to l-leucine. Consistent with l-leucine's anorexigenic role, we found that 25% of mouse MBH POMC neurons were activated by l-leucine. 10% of MBH NPY neurons were inhibited by l-leucine, and leucine rapidly reduced AGRP secretion, providing a mechanism for the rapid leucine-induced inhibition of foraging behavior in rodents. Surprisingly, none of the candidate mechanisms previously implicated in hypothalamic leucine sensing (K_ATP channels, mTORC1 signaling, amino-acid decarboxylation) were involved in the acute activity changes produced by l-leucine. Instead, our data indicate that leucine-induced neuronal activation involves a plasma membrane Ca²⁺ channel, whereas leucine-induced neuronal inhibition is mediated by inhibition of a store-operated Ca²⁺ current.

Conclusions

A subset of neurons in the mediobasal hypothalamus rapidly respond to physiological changes in extracellular leucine concentration. Leucine can produce both increases and decreases in neuronal Ca²⁺ concentrations in a neurochemically-diverse group of neurons, including some POMC and NPY/AGRP neurons. Our data reveal that leucine can signal through novel mechanisms to rapidly affect neuronal activity.

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A neurochemically diverse group of mouse and human hypothalamic neurons rapidly sense and respond to l-leucine.

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Leucine can produce neuronal activation or neuronal inhibition via distinct and novel Ca²⁺ signaling mechanisms.

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Leucine activates 25% ARH POMC neurons.

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Leucine inhibits 10% ARH NPY/AGRP neurons and reduces AGRP secretion from fasted mediobasal hypothalamic slices.

Experiences of stigma and discrimination in social and healthcare settings among trans people living with HIV in the UK

The People Living with HIV StigmaSurvey UK 2015 was a community led national survey investigating experiences of people living with HIV in the UK in the past 12 months. Participants aged 18 and over were recruited through over 120 cross-sector community organisations and 46 HIV clinics to complete an anonymous online survey. Trans is an umbrella term which refers to individuals whose current gender identity is different to the gender they were assigned at birth. Trans participants self-identified via gender identity and gender at birth questions. Descriptive analyses of reported experiences in social and health care settings were conducted and multivariate logistic regression analyses were used to identify sociodemographic predictors of reporting being treated differently to non-HIV patients, and being delayed or refused healthcare treatment in the past 12 months. 31 out of 1576 participants (2%) identified as trans (19 trans women, 5 trans men, 2 gender queer/non-binary, 5 other). High levels of social stigma were reported for all participants, with trans participants significantly more likely to report worrying about verbal harassment (39% vs. 23%), and exclusion from family gatherings (23% vs. 9%) in the last 12 months, compared to cisgender participants. Furthermore, 10% of trans participants reported physical assault in the last 12 months, compared to 4% of cisgender participants. Identifying as trans was a predictor of reporting being treated differently to non-HIV patients (48% vs. 30%; aOR 2.61, CI 1.06, 6.42) and being delayed or refused healthcare (41% vs. 16%; aOR 4.58, CI 1.83, 11.44). Trans people living with HIV in the UK experience high levels of stigma and discrimination, including within healthcare settings, which is likely to impact upon health outcomes. Trans-specific education and awareness within healthcare settings could help to improve service provision for this demographic.

Generation and Characterization of Functional Human Hypothalamic Neurons

Neurons in the hypothalamus orchestrate homeostatic physiological processes and behaviors essential for life. Defects in the function of hypothalamic neurons cause a spectrum of human diseases, including obesity, infertility, growth defects, sleep disorders, social disorders, and stress disorders. These diseases have been studied in animal models such as mice, but the rarity and relative inaccessibility of mouse hypothalamic neurons and species-specific differences between mice and humans highlight the need for human cellular models of hypothalamic diseases. We and others have developed methods to differentiate human pluripotent stem cells (hPSCs) into hypothalamic neurons and related cell types, such as astrocytes. This protocol builds on published studies by providing detailed step-by-step instructions for neuronal differentiation, quality control, long-term neuronal maintenance, and the functional interrogation of hypothalamic cells by calcium imaging. Together, these protocols should enable any group with appropriate facilities to generate and study human hypothalamic cells. © 2017 by John Wiley & Sons, Inc.

What is the overlap between HIV and shigellosis epidemics in England: further evidence of MSM transmission?

BACKGROUND

Evidence suggests that sexual transmission between men has replaced foreign travel as the predominant mode of Shigella transmission in England. However, sexuality and HIV status are not routinely recorded for laboratory-reported Shigella, and the role of HIV in the Shigella epidemic is not well understood.

METHODS

The Modular Open Laboratory Information System containing all Shigella cases reported to Public Health England (PHE) and the PHE HIV and AIDS Reporting System holding all adults living with diagnosed HIV in England were matched using a combination of Soundex code, date of birth and gender.

RESULTS

From 2004 to 2015, 88 664 patients were living with HIV, and 10 269 Shigella cases were reported in England; 9% (873/10 269) of Shigella cases were diagnosed with HIV, of which 93% (815/873) were in men. Shigella cases without reported travel history were more likely to be living with HIV than those who had travelled (14% (751/5427) vs 3% (134/4854); p<0.01). From 2004 to 2015, the incidence of Shigella in men with HIV rose from 47/100 000 to 226/100 000 (p<0.01) peaking in 2014 at 265/100 000, but remained low in women throughout the study period (0-24/100 000). Among Shigella cases without travel and with HIV, 91% (657/720) were men who have sex with men (MSM). HIV preceded Shigella diagnosis in 86% (610/720), and 65% (237/362) had an undetectable viral load (<50 copies/mL).

DISCUSSION

We observed a sustained increase in the national rate of shigellosis in MSM with HIV, who may experience more serious clinical disease. Sexual history, HIV status and STI risk might require sensitive investigation in men presenting with gastroenteritis.

Insidious Risk of Severe Mycobacterium chimaera Infection in Cardiac Surgery Patients

BACKGROUND

An urgent UK investigation was launched to assess risk of invasive Mycobacterium chimaera infection in cardiothoracic surgery and a possible association with cardiopulmonary bypass heater-cooler units following alerts in Switzerland and The Netherlands.

METHODS

Parallel investigations were pursued: (1) identification of cardiopulmonary bypass-associated M. chimaera infection through national laboratory and hospital admissions data linkage; (2) cohort study to assess patient risk; (3) microbiological and aerobiological investigations of heater-coolers in situ and under controlled laboratory conditions; and (4) whole-genome sequencing of clinical and environmental isolates.

RESULTS

Eighteen probable cases of cardiopulmonary bypass-associated M. chimaera infection were identified; all except one occurred in adults. Patients had undergone valve replacement in 11 hospitals between 2007 and 2015, a median of 19 months prior to onset (range, 3 months to 5 years). Risk to patients increased after 2010 from <0.2 to 1.65 per 10000 person-years in 2013, a 9-fold rise for infections within 2 years of surgery (rate ratio, 9.08 [95% CI, 1.81-87.76]). Endocarditis was the most common presentation (n = 11). To date, 9 patients have died. Investigations identified aerosol release through breaches in heater-cooler tanks. Mycobacterium chimaera and other pathogens were recovered from water and air samples. Phylogenetic analysis found close clustering of strains from probable cases.

CONCLUSIONS

We identified low but escalating risk of severe M. chimaera infection associated with heater-coolers with cases in a quarter of cardiothoracic centers. Our investigations strengthen etiological evidence for the role of heater-coolers in transmission and raise the possibility of an ongoing, international point-source outbreak. Active management of heater-coolers and heightened clinical awareness are imperative given the consequences of infection.

Development and function of human cerebral cortex neural networks from pluripotent stem cells in vitro

A key aspect of nervous system development, including that of the cerebral cortex, is the formation of higher-order neural networks. Developing neural networks undergo several phases with distinct activity patterns in vivo, which are thought to prune and fine-tune network connectivity. We report here that human pluripotent stem cell (hPSC)-derived cerebral cortex neurons form large-scale networks that reflect those found in the developing cerebral cortex in vivo. Synchronised oscillatory networks develop in a highly stereotyped pattern over several weeks in culture. An initial phase of increasing frequency of oscillations is followed by a phase of decreasing frequency, before giving rise to non-synchronous, ordered activity patterns. hPSC-derived cortical neural networks are excitatory, driven by activation of AMPA- and NMDA-type glutamate receptors, and can undergo NMDA-receptor-mediated plasticity. Investigating single neuron connectivity within PSC-derived cultures, using rabies-based trans-synaptic tracing, we found two broad classes of neuronal connectivity: most neurons have small numbers (<10) of presynaptic inputs, whereas a small set of hub-like neurons have large numbers of synaptic connections (>40). These data demonstrate that the formation of hPSC-derived cortical networks mimics in vivo cortical network development and function, demonstrating the utility of in vitro systems for mechanistic studies of human forebrain neural network biology.

Summary: Human PSC-derived cerebral cortex neurons form large-scale functional networks that change over time and mimic those found in the developing cerebral cortex in vivo.

Risk of invasive meningococcal disease in children and adults with HIV in England: a population-based cohort study

BACKGROUND

Recent studies have identified HIV infection as a potential risk factor for invasive meningococcal disease (IMD), suggesting that HIV-infected individuals could benefit from meningococcal vaccination to reduce their risk of this rare, but severe and potentially fatal infection. In the United Kingdom, as in most industrialised countries, HIV is not considered a risk factor for IMD.

METHODS

IMD incidence and relative risk by age group and meningococcal capsular group in HIV-positive compared with HIV-uninfected individuals was estimated through data linkage of national datasets in England between 2011 and 2013.

RESULTS

IMD incidence among persons diagnosed with HIV was 6.6 per 100,000 compared to 1.5 per 100,000 among HIV-negative individuals, with a relative risk of 4.5 (95 % CI, 2.7-7.5). All but one case occurred in adults aged 16-64 years, who had a 22.7-fold (95 % CI, 12.4-41.6; P <0.001) increased risk compared with the HIV-negative adults. IMD risk by capsular group varied with age. HIV-positive children and adolescents had a higher risk of meningococcal group B disease, while adults were at increased risk of groups C, W and Y disease. Most HIV-positive individuals had been born in Africa, had acquired HIV through heterosexual contact, and were known to be HIV-positive and receiving antiretroviral treatment at IMD diagnosis. The most common clinical presentation was septicemia and, although intensive care admission was common, none died of IMD.

CONCLUSIONS

HIV-positive children and adults are at significantly increased risk of IMD, providing an evidence base for policy makers to consider HIV as a risk factor for meningococcal vaccination.

APP metabolism regulates tau proteostasis in human cerebral cortex neurons

Accumulation of Aβ peptide fragments of the APP protein and neurofibrillary tangles of the microtubule-associated protein tau are the cellular hallmarks of Alzheimer's disease (AD). To investigate the relationship between APP metabolism and tau protein levels and phosphorylation, we studied human-stem-cell-derived forebrain neurons with genetic forms of AD, all of which increase the release of pathogenic Aβ peptides. We identified marked increases in intracellular tau in genetic forms of AD that either mutated APP or increased its dosage, suggesting that APP metabolism is coupled to changes in tau proteostasis. Manipulating APP metabolism by β-secretase and γ-secretase inhibition, as well as γ-secretase modulation, results in specific increases and decreases in tau protein levels. These data demonstrate that APP metabolism regulates tau proteostasis and suggest that the relationship between APP processing and tau is not mediated solely through extracellular Aβ signaling to neurons.

The phosphorylation status of Ascl1 is a key determinant of neuronal differentiation and maturation in vivo and in vitro

Generation of neurons from patient fibroblasts using a combination of developmentally defined transcription factors has great potential in disease modelling, as well as ultimately for use in regeneration and repair. However, generation of physiologically mature neurons in vitro remains problematic. Here we demonstrate the cell-cycle-dependent phosphorylation of a key reprogramming transcription factor, Ascl1, on multiple serine-proline sites. This multisite phosphorylation is a crucial regulator of the ability of Ascl1 to drive neuronal differentiation and maturation in vivo in the developing embryo; a phosphomutant form of Ascl1 shows substantially enhanced neuronal induction activity in Xenopus embryos. Mechanistically, we see that this un(der)phosphorylated Ascl1 is resistant to inhibition by both cyclin-dependent kinase activity and Notch signalling, both of which normally limit its neurogenic potential. Ascl1 is a central component of reprogramming transcription factor cocktails to generate neurons from human fibroblasts; the use of phosphomutant Ascl1 in place of the wild-type protein significantly promotes neuronal maturity after human fibroblast reprogramming in vitro. These results demonstrate that cell-cycle-dependent post-translational modification of proneural proteins directly regulates neuronal differentiation in vivo during development, and that this regulatory mechanism can be harnessed to promote maturation of neurons obtained by transdifferentiation of human cells in vitro.

A human stem cell model of early Alzheimer's disease pathology in Down syndrome

Human cellular models of Alzheimer's disease (AD) pathogenesis would enable the investigation of candidate pathogenic mechanisms in AD and the testing and developing of new therapeutic strategies. We report the development of AD pathologies in cortical neurons generated from human induced pluripotent stem (iPS) cells derived from patients with Down syndrome. Adults with Down syndrome (caused by trisomy of chromosome 21) develop early-onset AD, probably due to increased expression of a gene on chromosome 21 that encodes the amyloid precursor protein (APP). We found that cortical neurons generated from iPS cells and embryonic stem cells from Down syndrome patients developed AD pathologies over months in culture, rather than years in vivo. These cortical neurons processed the transmembrane APP protein, resulting in secretion of the pathogenic peptide fragment amyloid-β42 (Aβ42), which formed insoluble intracellular and extracellular amyloid aggregates. Production of Aβ peptides was blocked by a γ-secretase inhibitor. Finally, hyperphosphorylated tau protein, a pathological hallmark of AD, was found to be localized to cell bodies and dendrites in iPS cell-derived cortical neurons from Down syndrome patients, recapitulating later stages of the AD pathogenic process.

Human cerebral cortex development from pluripotent stem cells to functional excitatory synapses

Efforts to study the development and function of the human cerebral cortex in health and disease have been limited by the availability of model systems. Extrapolating from our understanding of rodent cortical development, we have developed a robust, multistep process for human cortical development from pluripotent stem cells: directed differentiation of human embryonic stem (ES) and induced pluripotent stem (iPS) cells to cortical stem and progenitor cells, followed by an extended period of cortical neurogenesis, neuronal terminal differentiation to acquire mature electrophysiological properties, and functional excitatory synaptic network formation. We found that induction of cortical neuroepithelial stem cells from human ES cells and human iPS cells was dependent on retinoid signaling. Furthermore, human ES cell and iPS cell differentiation to cerebral cortex recapitulated in vivo development to generate all classes of cortical projection neurons in a fixed temporal order. This system enables functional studies of human cerebral cortex development and the generation of individual-specific cortical networks ex vivo for disease modeling and therapeutic purposes.

Uteroplacental ischemia results in proteinuric hypertension and elevated sFLT-1

Preeclampsia is a complication of pregnancy with significant morbidity and mortality for the mother and the fetus. Presumptions are made that placental hypoxia has a causative role in the clinical syndrome. Furthermore, soluble fms-like tyrosine kinase 1 (sFLT-1) has been shown to have a role in the maternal syndrome of preeclampsia. We investigated the relationship between uteroplacental ischemia (UPI), the maternal clinical syndrome of preeclampsia and sFLT-1 in non-human primates. The induction of UPI in a pregnant non-human primate resulted in the development of a clinical entity analogous to human preeclampsia. This was illustrated by the increase in blood pressure, development of proteinuria, and renal histological changes identical to human preeclampsia. A significant elevation in the placental and peripheral blood mononuclear cell sFLT-1 mRNA expression was noted, translating to a significant elevation in circulating sFLT-1. Thus, this sequence suggests that a pathogenic reduction in placental perfusion results in the development of the maternal syndrome of preeclampsia and an increase in circulating sFLT-1, which is derived both from placental and extra-placental sources.

The development of novel organically modified sol-gel media for use with ATR/FTIR sensing

The ability to prepare and develop novel pre-concentration media by the sol-gel process, and their integration with mid-infrared transparent waveguides has been demonstrated. This research approach resulted in a mid-infrared sensing methodology in which the properties (porosity, functionality, polarity, etc.) of the recognition layer could be tailored by variation of the sol-gel precursors and processing conditions. Cross-linker type and concentration notably influenced p-xylene absorption and diffusion rate. Unreacted silanol groups appeared to be the dominant factor in the hydrophobicity of sol-gel layers. Variation of sol-gel precursors and thermal treatment altered both film cross-link density and polarity, as demonstrated by variation in the rate of analyte diffusion and equilibrium analyte concentration. The use of a novel 1 : 1 PTMOS : DPDMS material as pre-concentration medium in this analytical sensing approach was validated through the determination of p-nitrochlorobenzene in an aqueous environment. The response demonstrated linearity between 0-30 mg L(-1) with a correlation coefficient of 0.989 and a limit of detection of 0.7 mg L(-1). Sensing times for p-nitrochlorobenzene were also reduced from several hours to 24 minutes, without loss of measurement accuracy or sensitivity, by a 10 degrees C increase in the sensing temperature and the use of a predictive Fickian model previously developed by this research group.

Study of the impact of penetrant characteristics upon diffusion into Teflon membranes to further assess the performance of an ATR/FTIR sensor

In order to critically assess the performance and measuring dynamics of an attenuated total reflectance (ATR)/Fourier transform infrared (FTIR) sensor based on polymer preconcentration the impact of penetrant properties upon diffusion into the enrichment membrane must be characterised. Teflon AF2400, a highly amorphous and robust polymer not previously used in this role, was chosen as the enrichment membrane and various environmentally significant chlorinated hydrocarbon and alcohol species selected as analytes. Analyses were performed on aqueous solutions running in continuous flow configuration. Diffusion coefficients, calculated through regression of experimental data with simulated Fickian diffusion curves, were employed as the primary indicator of diffusion behaviour. Penetrant size and shape were both demonstrated to exhibit a substantial impact upon diffusion behaviour. Significant multi-component effects were observed for the simultaneous detection of two analytes. The results presented highlight the necessity for full characterisation of the observed effects prior to the development of a sensing technology for real applications.

Determination of hydrocarbons using sapphire fibers coated with poly(dimethylsiloxane)

A poly(dimethylsiloxane) (PDMS) coated sapphire fiber has been investigated as a sensor for hydrocarbons (HCs) in the mid-infrared region around 3000 cm(-1). In order to optimize and predict sensor response, the diffusion behavior of the analytes into the PDMS preconcentration medium has been examined. A diffusion model based on Fickian diffusion was used to quantify diffusion. The model incorporated such factors as film thickness, refractive index of the polymer and the fiber core, and principal wavelength at which the analyte absorbs. A range of hydrocarbons, from hexane to pentadecane, was analyzed at 2930 cm(-1) using both fiber-coupled Fourier transform infrared spectroscopy and a modular prototype system. Diffusion coefficients were determined for these compounds and diffusion behavior examined and related to factors such as analyte polarity and molecular size. The diffusion coefficients were found to range from 6.41 x 10(-11) 5 x 10(-12) to 5.25 x 10(-11) +/- 9 x 10(-13) cm2 s(-1) for hexane and pentadecane into a 2.9 microm PDMS film, respectively. The diffusion model was also used to examine the effect of changing system parameters such as film thickness in order to characterize sensor response.

Pragmatic randomized trial of antenatal intervention to prevent post-natal depression by reducing psychosocial risk factors

BACKGROUND

Social support theory and observational risk factor studies suggest that increased antenatal psychosocial support could prevent post-natal depression. We used empirical knowledge of risk and protective factors for post-natal depression not employed previously in order to develop and evaluate an antenatal preventive intervention.

METHODS

We conducted a pragmatic randomized controlled trial in antenatal clinics. We screened 1300 primiparous women and 400 screened positive, 69 screen-positive women were untraceable or not eligible. Of 292 women who completed baseline assessment, 209 consented to randomization, of these 190 provided outcome data 3 months post-natally. 'Preparing for Parenthood', a structured antenatal risk factor reducing intervention designed to increase social support and problem-solving skills, was compared with routine antenatal care only. We compared the percentage depressed at 3 months after childbirth using the self-completion General Health Questionnaire Depression scale and Edinburgh Post-natal Depression Scale (EPDS), and the Schedules for Clinical Assessment in Neuropsychiatry a systematic clinical interview.

RESULTS

Assignment to the intervention group did not significantly impact on post-natal depression (odds ratio for GHQ-Depression 1.22 (95% CI 0.63-2.39), P = 0.55) or on risk factors for depression. Forty-five per cent of the intervention group women attended sufficient sessions to be likely to benefit from intervention if effective. Attenders benefited no more than non-attenders.

CONCLUSIONS

Prevention services targeting post-natal depression should not implement antenatal support programmes on these lines until further research has demonstrated the feasibility and effectiveness of such methods. The development of novel, low cost interventions effective in reducing risk factors should be completed before further trial evaluation.

Issues of consent in colonoscopy: if a patient says 'stop' should we continue?

Colonoscopy is generally performed under intravenous sedation, which may alter a patient's responses and perception. What should be done if, during the procedure, a patient withdraws the consent previously given? The views of gastroenterologists and patients were ascertained by mailing questionnaires to 100 members of the British Society of Gastroenterology and to 100 patients who had undergone colonoscopy with intravenous sedation. Only 1 of 59 eligible consultants who replied said they would stop the procedure after a single request, but a further 51 would stop if repeatedly asked to do so. Of the remaining 7 who would complete the procedure, 1 nevertheless believed that a sedated patient is capable of making a rational decision. Of the 51 patients who returned a usable questionnaire, 25 thought that the procedure should be stopped immediately following a request, while 26 felt that the doctor should continue. The divergent and sometimes inconsistent views found in this study highlighted the need for further clarification of the issue of informed consent for procedures conducted with the patient under sedation.

Changes of extracellular matrix in a baboon (Papio hamadryas) model of insulin dependent diabetes: studies using electron microscopy and X-ray diffraction techniques

Extracellular matrix plays an important role in many physiological functions and its abnormalities are thought to play a key role in the pathogenesis of diabetic complications. In this paper we used the techniques of electron microscopy, immunostaining and X-ray diffraction to document some of the early events in the changes of extracellular matrix in a model of insulin dependent diabetes in baboons. Our results show that thickening of basement membrane and enlargement of mesangium are demonstrable in the glomeruli of prepubertal diabetic baboons within 2 years from the onset of diabetes. Concomitant with this was the accumulation of type IV collagen and laminin in the mesangium. By contrast, even the very sensitive technique of X-ray diffraction failed to demonstrate changes in the equatorial direction of collagen molecules of the skin and tendon. We conclude that changes of glomerular extracellular matrix are demonstrable early in insulin dependent diabetes even in prepubertal baboons. These can be used as endpoints in evaluating the efficacy of pharmacological agents such as aminoguanidine in preventing diabetic complications.

Chrysiasis after low-dose gold and UV light exposure

We describe a case of chrysiasis in a 54-year-old woman. The diagnosis was confirmed by light microscopy, transmission electron microscopy, and radiographic microanalysis. The condition developed after a relatively low dose of gold. We propose that chrysiasis developed because of the patient's exposure to the intense UV light in Australia.

The pattern of glomerular disease in New Caledonia: preliminary findings

Two hundred and two renal biopsies from 181 patients in New Caledonia were classified into either primary glomerulonephritis or glomerulopathy associated with systemic disease. These were then compared with 670 similar biopsies from 634 in-patients at Sydney's Royal Prince Alfred Hospital (RPAH). The most prevalent primary glomerular disease among the New Caledonian cases was focal segmental glomerulosclerosis, compared with IgA disease among the RPAH cases. Mesangiocapillary glomerulonephritis, post-infectious glomerulonephritis and minimal lesion nephropathy were all relatively commoner among the New Caledonian biopsies, but the numbers were small. The most prevalent systemic glomerulopathy in the New Caledonian cases were amyloidosis. This was the least common among our RPAH group. Diabetes mellitus and lupus nephritis were also slightly more common in the New Caledonian group. Focal necrotizing/crescentic glomerulonephritis was unusual in the New Caledonian samples, while it was the most common systemic glomerulopathy among the RPAH group.

The direct effects of diethylstilboestrol and nifedipine on the contractile responses of isolated human and rat detrusor muscles

We have studied the direct effect of 2 mumol.l-1 diethylstilboestrol on isolated rat and human detrusor muscles. Diethylstilboestrol significantly reduced the amplitude of the contractile response of rat detrusor muscle to stimulation with acetylcholine, carbachol, electrical field stimulation, and 5-hydroxytryptamine. In isolated human bladder it also significantly reduced contractions stimulated with acetylcholine, carbachol, and electrical field stimulation. In depolarized rat detrusor muscle stimulated with different concentrations of calcium ions, the contractile responses were significantly reduced by the addition of diethylstilboestrol. Diethylstilboestrol also significantly reduced the amplitude of contractile response to potassium chloride. The inhibitory action of diethylstilboestrol was enhanced by the reduction of extracellular calcium ions, the maximum contractile response to acetylcholine, carbachol, and electrical field stimulation being reduced by a further 32%, 23%, and 45% respectively. Diethylstilboestrol did not have a significant effect on carbachol-induced contractions in depolarized rat detrusor muscle suspended in a calcium-free environment. Diethylstilboestrol was effective in blocking rat and human detrusor muscle contraction. The likely mechanism is a reduction of the influx of calcium ions into the cell during contraction rather than an effect on intracellular calcium release. These results give support for treating incontinent patients with drugs that block calcium ion uptake, and may suggest a further beneficial effect of oestrogen therapy in postmenopausal women.

Suicide in a rural Irish population

As part of a general survey of psychiatric morbidity in a newly created community based rural psychiatric service, data was collected on suicide from the relevant Coroners for the year January 1989-December 1989. A total of 11 suicides were discovered for a population of 60,735 giving a suicide rate of 18.04/100,000. The official figure for the same period is 252 deaths due to suicide or 7.1/100,000. The implications of these findings are discussed.

Advanced ovarian cancer: long-term results following chemotherapy and second-look laparotomy

Thirty patients who showed a complete clinical response to cis-platinum-containing combination chemotherapy underwent second-look laparotomy. Seventeen patients (56.7%) achieved a pathologically confirmed complete remission as documented by a negative second-look laparotomy. After a minimum follow-up of 60 months, 6 of 17 patients developed recurrent disease and subsequently died. Due to the occurrence of late relapse in these negative second-look patients routine second-look laparotomy to confirm pathological response cannot be justified. Ten of thirty patients underwent secondary cytoreductive surgery at second-look operation. All ten patients had suboptimal initial debulking surgery. Five of these ten patients (50%) survived 4 years. Secondary cytoreductive surgery may improve survival in patients who undergo suboptimal initial debulking surgery.