Assessment of fragment docking and scoring with the endothiapepsin model system

Fragment-based screening has become indispensable in drug discovery. Yet, the weak binding affinities of these small molecules still represent a challenge for the reliable detection of fragment hits. The extent of this issue was illustrated in the literature for the aspartic protease endothiapepsin: When seven biochemical and biophysical in vitro screening methods were applied to screen a library of 361 fragments, very poor overlap was observed between the hit fragments identified by the individual approaches, resulting in high levels of false positive and/or false negative results depending on the mutually compared methods. Here, the reported in vitro findings are juxtaposed with the results from in silico docking and scoring approaches. The docking programs GOLD and Glide were considered with the scoring functions ASP, ChemScore, ChemPLP, GoldScore, DSXCSD, and GlideScore. First, the ranking power and scoring power were assessed for the named scoring functions. Second, the capability of reproducing the crystallized fragment binding modes was tested in a structure-based redocking approach. The redocking success notably depended on the ligand efficiency of the considered fragments. Third, a blinded virtual screening approach was employed to evaluate whether in silico screening can compete with in vitro methods in the enrichment of fragment databases.

Thetha Nami ngithethe nawe (Let's Talk): a stepped-wedge cluster randomised trial of social mobilisation by peer navigators into community-based sexual health and HIV care, including pre-exposure prophylaxis (PrEP), to reduce sexually transmissible HIV amongst young people in rural KwaZulu-Natal, South Africa

BACKGROUND

Antiretroviral therapy (ART) through universal test and treat (UTT) and HIV pre-exposure prophylaxis (PrEP) substantially reduces HIV-related mortality and incidence. Effective ART based prevention has not translated into population-level impact in southern Africa due to sub-optimal coverage among youth. We aim to investigate the effectiveness, implementation and cost effectiveness of peer-led social mobilisation into decentralised integrated HIV and sexual reproductive health (SRH) services amongst adolescents and young adults in KwaZulu-Natal (KZN).

METHODS

We are conducting a type 1a hybrid effectiveness/implementation study, with a cluster randomized stepped-wedge trial (SWT) to assess effectiveness and a realist process evaluation to assess implementation outcomes. The SWT will be conducted in 40 clusters in rural KZN over 45 months. Clusters will be randomly allocated to receive the intervention in period 1 (early) or period 2 (delayed). 1) Intervention arm: Resident peer navigators in each cluster will approach young men and women aged 15-30 years living in their cluster to conduct health, social and educational needs assessment and tailor psychosocial support and health promotion, peer mentorship, and facilitate referrals into nurse led mobile clinics that visit each cluster regularly to deliver integrated SRH and differentiated HIV prevention (HIV testing, UTT for those positive, and PrEP for those eligible and negative). Standard of Care is UTT and PrEP delivered to 15-30 year olds from control clusters through primary health clinics. There are 3 co-primary outcomes measured amongst cross sectional surveys of 15-30 year olds: 1) effectiveness of the intervention in reducing the prevalence of sexually transmissible HIV; 2) uptake of universal risk informed HIV prevention intervention; 3) cost of transmissible HIV infection averted. We will use a realist process evaluation to interrogate the extent to which the intervention components support demand, uptake, and retention in risk-differentiated biomedical HIV prevention.

DISCUSSION

The findings of this trial will be used by policy makers to optimize delivery of universal differentiated HIV prevention, including HIV pre-exposure prophylaxis through peer-led mobilisation into community-based integrated adolescent and youth friendly HIV and sexual and reproductive health care.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier-NCT05405582. Registered: 6th June 2022.

Analysis of Structure-Activity Relationships of Novel Inhibitors of the Macrophage Infectivity Potentiator (Mip) Proteins of Neisseria meningitidis, Neisseria gonorrhoeae, and Burkholderia pseudomallei

The macrophage infectivity potentiator (Mip) protein is a promising target for developing new drugs to combat antimicrobial resistance. New rapamycin-derived Mip inhibitors have been designed that may be able to combine two binding modes to inhibit the Mip protein of Burkholderia pseudomallei (BpMip). These novel compounds are characterized by an additional substituent in the middle chain linking the lateral pyridine to the pipecoline moiety, constituting different stereoisomers. These compounds demonstrated high affinity for the BpMip protein in the nanomolar range and high anti-enzymatic activity and ultimately resulted in significantly reduced cytotoxicity of B. pseudomallei in macrophages. They also displayed strong anti-enzymatic activity against the Mip proteins of Neisseria meningitidis and Neisseria gonorrhoeae and substantially improved the ability of macrophages to kill the bacteria. Hence, the new Mip inhibitors are promising, non-cytotoxic candidates for further testing against a broad spectrum of pathogens and infectious diseases.

Adaptation and pre-test of a shortened Stepping Stones and Creating Futures intervention focused on HIV for young men in rural South Africa

Men's engagement in HIV prevention and treatment is suboptimal, including in South Africa. We sought to address this through adapting an evidence-based intervention, Stepping Stones and Creating Futures (SSCF), to strengthen its HIV content and provide a more scalable (shorter) intervention in rural South Africa. We then conducted a mixed methods pre-test of the intervention among young men aged 18-35 years. To adapt SSCF, we reviewed the current evidence base and worked with male Peer Navigators to update the SSCF theory of change (ToC) and manual. The revised intervention was ~45 hours (9 sessions) as opposed to ~63 hours and included a greater focus on HIV prevention and treatment technologies. Overall, 64% (n = 60) of men approached agreed to participate in the intervention, uptake (attending one session) among those who agreed was n = 35(58%) and retention (attending 6 or more sessions) was n = 25(71%). Qualitative data emphasized the intervention was acceptable, with young men describing it as something they liked. The qualitative data also broadly supported the intervention ToC, including the normalization of HIV in men's lives, and the importance of health for men in achieving their life goals. However, it also highlighted the need to focus more on HIV-related stigma and fear, and the importance of HIV self-testing kits in encouraging testing. We revised the ToC and manual in light of this data. The adapted SSCF is acceptable and supports the ToC. Next steps is an evaluation to look at effectiveness of the intervention.

Glucose consumption and gene expression in granulosa cells collected before and after in vitro oocyte maturation in the southern white rhinoceros (Ceratotherium simum simum)

CONTEXT

With two northern white rhinos (NWR) remaining, the continued existence of this species relies on studying their relative, the southern white rhino (SWR).

AIMS

(1) Characterise gene expression in granulosa cells (GC) from SWR cumulus oocyte complexes (COCs) prior to (Pre-) and after (Post-) in vitro maturation (IVM), comparing culture media and oocytes from donors treated with or without gonadotropin stimulation prior to ovum recovery; and (2) evaluate COC glucose consumption in spent media.

METHODS

COCs were retrieved from four SWRs. Granulosa cells were collected before and after IVM in SDZ or IZW medium. Total RNA was evaluated by qPCR.

KEY RESULTS

Oocyte maturation was greater in SDZ than IZW media. Expression of genes associated with follicle development increased in Pre-IVM GC. Six genes were differentially expressed in Post-IVM GC from stimulated compared to unstimulated donors. COCs from stimulated animals consumed more glucose. Fifty seven percent of oocytes in SDZ medium consumed all available glucose.

CONCLUSIONS

Gene expression changed upon in vitro maturation and gonadotropin stimulation. Higher glucose availability might be needed during IVM.

IMPLICATIONS

This is the first study examining GC gene expression and COC metabolic requirements in rhinoceros, which are critical aspects to optimise IVM of rhinoceros oocytes.

The association of exposure to DREAMS on sexually acquiring or transmitting HIV amongst adolescent girls and young women living in rural South Africa

OBJECTIVE

We investigate how risk of sexually acquiring or transmitting HIV in adolescent girls and young women (AGYW) changed following the real-world implementation of DREAMS (Determined, Resilient, Empowered, AIDS free, Mentored and Safe) HIV prevention programme.

DESIGN

A representative population-based prospective cohort study of AGYW living in rural KwaZulu-Natal.

METHODS

Between 2017 and 2019, we interviewed a random sample of AGYW aged 13-22 years annually. We measured exposure to DREAMS as self-reported receipt of an invitation to participate and/or participation in DREAMS activities that were provided by DREAMS implementing organizations. HIV and herpes simplex virus type 2 (HSV-2) statuses were ascertained through blood tests on Dried Blood Spot (DBS). We used multivariable regression analysis to assess the association between exposure to DREAMS and risk of acquiring HIV: measured as incident HSV-2 (a proxy of sexual risk) and incident HIV;and the risk of sexually transmitting HIV: measured as being HIV positive with a detectable HIV viral load (≥50 copie/ml) on the last available DBS. We adjusted for sociodemographic, sexual relationship, and migration.

RESULTS

Two thousand one hundred and eighty-four (86.4%) of those eligible agreed to participate and 2016 (92.3%) provided data for at least one follow-up time-point. One thousand and thirty (54%) were exposed to DREAMS;HIV and HSV-2 incidence were 2.2/100 person-years [95% confidence interval (CI) 1.66-2.86] and 17.3/100 person-years (95% CI 15.5-19.4), respectively. There was no evidence that HSV-2 and HIV incidence were lower in those exposed to DREAMS: adjusted rate ratio (aRR) 0.96 (95% CI 0.76-1.23 and 0.83 (95% CI 0.46-1.52), respectively. HIV viral load was detectable for 169 (8.9%) respondents;there was no evidence this was lower in those exposed to DREAMS with an adjusted risk difference, compared with those not exposed to DREAMS, of 0.99% (95% CI-1.52 to 3.82]. Participants who lived in peri-urban/ urban setting were more likely to have incident HIV and transmissible HIV. Both HSV-2 incidence and the transmissible HIV were associated with older age and ever having sex. Findings did not differ substantively by respondent age group.

CONCLUSION

DREAMS exposure was not associated with measurable reductions in risk of sexually acquiring or transmitting HIV amongst a representative cohort of AGYW in rural South Africa.

Isisekelo Sempilo study protocol for the effectiveness of HIV prevention embedded in sexual health with or without peer navigator support (Thetha Nami) to reduce prevalence of transmissible HIV amongst adolescents and young adults in rural KwaZulu-Natal: a 2 × 2 factorial randomised controlled trial

Background

Antiretroviral therapy (ART) through universal test and treat (UTT) and HIV pre-exposure prophylaxis (PrEP) substantially reduces HIV-related mortality, morbidity and incidence. Effective individual-level prevention modalities have not translated into population-level impact in southern Africa due to sub-optimal coverage among adolescents and youth who are hard to engage. We aim to investigate the feasibility, acceptability, and preliminary population level effectiveness of HIV prevention services with or without peer support to reduce prevalence of transmissible HIV amongst adolescents and young adults in KwaZulu-Natal.

Methods

We are conducting a 2 × 2 factorial trial among young men and women aged 16–29 years, randomly selected from the Africa Health Research Institute demographic surveillance area. Participants are randomly allocated to one of four intervention combinations: 1) Standard of Care (SOC): nurse-led services for HIV testing plus ART if positive or PrEP for those eligible and negative; 2) Sexual and Reproductive Health (SRH): Baseline self-collected vaginal and urine samples with study-organized clinic appointments for results, treatment and delivery of HIV testing, ART and PrEP integrated with SRH services; 3) Peer-support: Study referral of participants to a peer navigator to assess their health, social and educational needs and provide risk-informed HIV prevention, including facilitating clinic attendance; or 4) SRH + peer-support.

The primary outcomes for effectiveness are: (1) the proportion of individuals with infectious HIV at 12 months and (2) uptake of risk-informed comprehensive HIV prevention services within 60 days of enrolment. At 12 months, all participants will be contacted at home and the study team will collect a dried blood spot for HIV ELISA and HIV viral load testing.

Discussion

This trial will enable us to understand the relative importance of SRH and peer support in creating demand for effective and risk informed biomedical HIV prevention and preliminary data on their effectiveness on reducing the prevalence of transmissible HIV amongst all adolescents and youth.

Trial registration

Trial Registry: clincialtrials.gov. ClinicalTrials.gov Identifier NCT04532307. Registered: March 2020.

Process evaluation of peer-to-peer delivery of HIV self-testing and sexual health information to support HIV prevention among youth in rural KwaZulu-Natal, South Africa: qualitative analysis

OBJECTIVE

Peer-to-peer (PTP) HIV self-testing (HIVST) distribution models can increase uptake of HIV testing and potentially create demand for HIV treatment and pre-exposure prophylaxis (PrEP). We describe the acceptability and experiences of young women and men participating in a cluster randomised trial of PTP HIVST distribution and antiretroviral/PrEP promotion in rural KwaZulu-Natal.

METHODS

Between March and September 2019, 24 pairs of trained peer navigators were randomised to two approaches to distribute HIVST packs (kits+HIV prevention information): incentivised-peer-networks where peer-age friends distributed packs within their social network for a small incentive, or direct distribution where peer navigators distributed HIVST packs directly. Standard-of-care peer navigators distributed information without HIVST kits. For the process evaluation, we conducted semi-structured interviews with purposively sampled young women (n=30) and men (n=15) aged 18-29 years from all arms. Qualitative data were transcribed, translated, coded manually and thematically analysed using an interpretivist approach.

RESULTS

Overall, PTP approaches were acceptable and valued by young people. Participants were comfortable sharing sexual health issues they would not share with adults. Coupled with HIVST, peer (friends) support facilitated HIV testing and solidarity for HIV status disclosure and treatment. However, some young people showed limited interest in other sexual health information provided. Some young people were wary of receiving health information from friends perceived as non-professionals while others avoided sharing personal issues with peer navigators from their community. Referral slips and youth-friendly clinics were facilitators to PrEP uptake. Family disapproval, limited information, daily pills and perceived risks were major barriers to PrEP uptake.

CONCLUSION

Both professional (peer navigators) and social network (friends) approaches were acceptable methods to receive HIVST and sexual health information. Doubts about the professionalism of friends and overly exclusive focus on HIVST information materials may in part explain why HIVST kits, without peer navigators support, did not create demand for PrEP.

Thetha Nami: participatory development of a peer-navigator intervention to deliver biosocial HIV prevention for adolescents and youth in rural South Africa

BACKGROUND

Despite effective biomedical tools, HIV remains the largest cause of morbidity/mortality in South Africa - especially among adolescents and young people. We used community-based participatory research (CBPR), informed by principles of social justice, to develop a peer-led biosocial intervention for HIV prevention in KwaZulu-Natal (KZN).

METHODS

Between March 2018 and September 2019 we used CBPR to iteratively co-create and contextually adapt a biosocial peer-led intervention to support HIV prevention. Men and women aged 18-30 years were selected by community leaders of 21 intervention implementation areas (izigodi) and underwent 20 weeks of training as peer-navigators. We synthesised quantitative and qualitative data collected during a 2016-2018 study into 17 vignettes illustrating the local drivers of HIV. During three participatory intervention development workshops and community mapping sessions, the peer-navigators critically engaged with vignettes, brainstormed solutions and mapped the components to their own izigodi. The intervention components were plotted to a Theory of Change which, following a six-month pilot and process evaluation, the peer-navigators refined. The intervention will be evaluated in a randomised controlled trial ( NCT04532307 ).

RESULTS

Following written and oral assessments, 57 of the 108 initially selected participated in two workshops to discuss the vignettes and co-create the Thetha Nami (`talk to me'). The intervention included peer-led health promotion to improve self-efficacy and demand for HIV prevention, referrals to social and educational resources, and aaccessible youth-friendly clinical services to improve uptake of HIV prevention. During the pilot the peer-navigators approached 6871 young people, of whom 6141 (89%) accepted health promotion and 438 were linked to care. During semi-structured interviews peer-navigators described the appeal of providing sexual health information to peers of a similar age and background but wanted to provide more than just "onward referral". In the third participatory workshop 54 peer-navigators refined the Thetha Nami intervention to add three components: structured assessment tool to tailor health promotion and referrals, safe spaces and community advocacy to create an enabling environment, and peer-mentorship and navigation of resources to improve retention in HIV prevention.

CONCLUSION

Local youth were able to use evidence to develop a contextually adapted peer-led intervention to deliver biosocial HIV prevention.

Deep learning of HIV field-based rapid tests

Although deep learning algorithms show increasing promise for disease diagnosis, their use with rapid diagnostic tests performed in the field has not been extensively tested. Here we use deep learning to classify images of rapid human immunodeficiency virus (HIV) tests acquired in rural South Africa. Using newly developed image capture protocols with the Samsung SM-P585 tablet, 60 fieldworkers routinely collected images of HIV lateral flow tests. From a library of 11,374 images, deep learning algorithms were trained to classify tests as positive or negative. A pilot field study of the algorithms deployed as a mobile application demonstrated high levels of sensitivity (97.8%) and specificity (100%) compared with traditional visual interpretation by humans-experienced nurses and newly trained community health worker staff-and reduced the number of false positives and false negatives. Our findings lay the foundations for a new paradigm of deep learning-enabled diagnostics in low- and middle-income countries, termed REASSURED diagnostics1, an acronym for real-time connectivity, ease of specimen collection, affordable, sensitive, specific, user-friendly, rapid, equipment-free and deliverable. Such diagnostics have the potential to provide a platform for workforce training, quality assurance, decision support and mobile connectivity to inform disease control strategies, strengthen healthcare system efficiency and improve patient outcomes and outbreak management in emerging infections.

Ambient particulate matter burden of disease in the Kingdom of Saudi Arabia

BACKGROUND

Air pollution is one of the top 10 global health risk factors and has been associated with premature mortality, cardiovascular, cerebrovascular, respiratory, and metabolic disease. Currently, there is a lack of health assessments on the public health impacts of air pollution in the Kingdom of Saudi Arabia.

AIM

This study aims to assess the ambient particulate matter burden of disease in the Kingdom of Saudi Arabia.

METHODS

A comparative risk assessment (CRA) using the 2017 Global Burden of Disease was performed to estimate ambient particulate matter exposure, mortality, and lost years of a healthy life. Saudi Arabia population-weighted mean concentrations of particle mass with an aerodynamic diameter less than 2·5 μm (PM2.5), at an approximate 11 km × 11 km resolution was estimated using satellite-based estimates, chemical transport models, and ground-level measurements. The CRA for PM2.5 was based on relative risks originated from epidemiological studies using integrated exposure-response functions for ischemic heart disease, cerebrovascular disease, chronic obstructive pulmonary disease, lung cancer, lower respiratory infections, and type 2 diabetes. Mortality, years of life lost (YLL), years lived with disability (YLD) and disability-adjusted life years (DALYs) attributable to PM2.5 were estimated at the national level for all ages and both sexes from 1990 to 2017.

RESULTS

In 2017, the annual exposure to ambient particulate matter in the population-weighted mean PM2.5 in Saudi Arabia was 87.9 μg/m³ (95% UI 29.6-197.9). The PM2.5 population-weighted mean has increased by 24% since 1990. Annual deaths attributable to PM2.5 were estimated at 8536 (95% UI 6046-11,080), representing 9% of the total annual deaths in Saudi Arabia. In 2017, 315,200 (95% UI 231,608-401,926) DALYs were attributable to PM2.5. Males contributed to 67% (209,822 (95% UI 151,322-277,503)) of DALYs, and females contributed to 33% (105,378 (95% UI 76,014-135,269) of DALYs. Ischemic heart disease represented 44% of the PM2.5 attributable DALYs, followed by type 2 diabetes (20%), lower respiratory infections (13%), stroke (11%), COPD (10%), and tracheal, bronchus, and lung cancer (3%). In 2017, 240,966 (95% UI 168,833-319,178) years of life lost (YLL) and 74,234 (95% UI 50,229-100,410) years lived with disability (YLD) were attributed to PM2.5.

CONCLUSION

Ambient particulate matter is the fifth health risk factor in Saudi Arabia, contributing 9% of total mortality. Over the past 27 years, estimated exposure levels of PM2.5 in Saudi Arabia have been above WHO's air quality guidelines. Although since 2011 mortality and DALY rates attributable to PM2.5 have decreased, air pollution concentrations continue to increase. National and local authorities in Saudi Arabia should consider policies to reduce industrial and traffic-related air pollution in combination with the strengthening of current investments and improvements in health care and prevention services.

A Continuous Quality Improvement Intervention to Improve Antenatal HIV Care Testing in Rural South Africa: Evaluation of Implementation in a Real-World Setting

Background: We evaluated continuous quality improvement (CQI) targeting antenatal HIV care quality in rural South Africa using a stepped-wedge cluster-randomised controlled trial (Management and Optimisation of Nutrition, Antenatal, Reproductive, Child health, MONARCH) and an embedded process evaluation. Here, we present results of the process evaluation examining determinants of CQI practice and ‘normalisation.’

Methods: A team of CQI mentors supported public-sector health workers in seven primary care clinics to (1) identify root causes of poor HIV viral load (VL) monitoring among pregnant women living with HIV and repeat HIV testing among pregnant women not living with HIV, and (2) design and iteratively test their own solutions. We used a mixed methods evaluation with field notes from CQI mentors (‘dose’ and ‘reach’ of CQI, causes of poor HIV care testing rates, implemented change ideas); patient medical records (HIV care testing by clinic and time step); and semi-structured interviews with available health workers. We analysed field notes and semi-structured interviews for determinants of CQI implementation and ‘normalisation’ using Normalisation Process Theory (NPT) and Tailored Implementation of Chronic Diseases (TICD) frameworks.

Results: All interviewed health workers found the CQI mentors and methodology helpful for quality improvement. Total administered ‘dose’ was higher than planned but ‘reach’ was limited by resource constraints, particularly staffing shortages. Simple workable improvements to identified root causes were implemented, such as a patient tracking notebook and results filing system. VL monitoring improved over time, but not repeat HIV testing. Besides resource constraints, gaps in knowledge of guidelines, lack of leadership, poor clinical documentation, and data quality gaps reduced CQI implementation fidelity and normalisation.

Conclusion: While CQI holds promise, we identified several health system challenges. Priorities for policy makers include improving staffing and strategies to improve clinical documentation. Additional support with implementing clinical guidelines and improving routine data quality are needed. Normalising CQI may be challenging without concurrent health system improvements.

Spatial-numerical associations in the presence of an avatar

When we interact with other people or avatars, they often provide an alternative spatial frame of reference compared to our own. Previous studies introduced avatars into stimulus–response compatibility tasks and demonstrated compatibility effects as if the participant was viewing the task from the avatar’s point of view. However, the origin of this effect of perspective taking remained unclear. To distinguish changes in stimulus coding from changes in response coding, caused by the avatar, two experiments were conducted that combined a SNARC task and a spontaneous visual perspective taking task to specify the role of response coding. We observed compatibility effects that were based on the avatar’s perspective rather than the participants’ own. Because number magnitude was independent of the avatar’s perspective, the observed changes in compatibility caused by different perspectives indicate changes in response coding. These changes in response coding are only significant when they are accompanied by visual action effects.

The impact of continuous quality improvement on coverage of antenatal HIV care tests in rural South Africa: Results of a stepped-wedge cluster-randomised controlled implementation trial

BACKGROUND

Evidence for the effectiveness of continuous quality improvement (CQI) in resource-poor settings is very limited. We aimed to establish the effects of CQI on quality of antenatal HIV care in primary care clinics in rural South Africa.

METHODS AND FINDINGS

We conducted a stepped-wedge cluster-randomised controlled trial (RCT) comparing CQI to usual standard of antenatal care (ANC) in 7 nurse-led, public-sector primary care clinics-combined into 6 clusters-over 8 steps and 19 months. Clusters randomly switched from comparator to intervention on pre-specified dates until all had rolled over to the CQI intervention. Investigators and clusters were blinded to randomisation until 2 weeks prior to each step. The intervention was delivered by trained CQI mentors and included standard CQI tools (process maps, fishbone diagrams, run charts, Plan-Do-Study-Act [PDSA] cycles, and action learning sessions). CQI mentors worked with health workers, including nurses and HIV lay counsellors. The mentors used the standard CQI tools flexibly, tailored to local clinic needs. Health workers were the direct recipients of the intervention, whereas the ultimate beneficiaries were pregnant women attending ANC. Our 2 registered primary endpoints were viral load (VL) monitoring (which is critical for elimination of mother-to-child transmission of HIV [eMTCT] and the health of pregnant women living with HIV) and repeat HIV testing (which is necessary to identify and treat women who seroconvert during pregnancy). All pregnant women who attended their first antenatal visit at one of the 7 study clinics and were ≥18 years old at delivery were eligible for endpoint assessment. We performed intention-to-treat (ITT) analyses using modified Poisson generalised linear mixed effects models. We estimated effect sizes with time-step fixed effects and clinic random effects (Model 1). In separate models, we added a nested random clinic-time step interaction term (Model 2) or individual random effects (Model 3). Between 15 July 2015 and 30 January 2017, 2,160 participants with 13,212 ANC visits (intervention n = 6,877, control n = 6,335) were eligible for ITT analysis. No adverse events were reported. Median age at first booking was 25 years (interquartile range [IQR] 21 to 30), and median parity was 1 (IQR 0 to 2). HIV prevalence was 47% (95% CI 42% to 53%). In Model 1, CQI significantly increased VL monitoring (relative risk [RR] 1.38, 95% CI 1.21 to 1.57, p < 0.001) but did not improve repeat HIV testing (RR 1.00, 95% CI 0.88 to 1.13, p = 0.958). These results remained essentially the same in both Model 2 and Model 3. Limitations of our study include that we did not establish impact beyond the duration of the relatively short study period of 19 months, and that transition steps may have been too short to achieve the full potential impact of the CQI intervention.

CONCLUSIONS

We found that CQI can be effective at increasing quality of primary care in rural Africa. Policy makers should consider CQI as a routine intervention to boost quality of primary care in rural African communities. Implementation research should accompany future CQI use to elucidate mechanisms of action and to identify factors supporting long-term success.

TRIAL REGISTRATION

This trial is registered at ClinicalTrials.gov under registration number NCT02626351.

Infant feeding knowledge and practice vary by maternal HIV status: a nested cohort study in rural South Africa

Background

We investigate whether correct infant feeding knowledge and practice differ by maternal HIV status in an era of evolving clinical guidelines in rural South Africa.

Methods

This cohort study was nested within the MONARCH stepped-wedge cluster-randomised controlled trial (www.clinicaltrials.gov: NCT02626351) which tested the impact of continuous quality improvement on antenatal care quality at seven primary care clinics in KwaZulu-Natal, from July 2015 to January 2017. Women aged ≥18 years at delivery were followed up to 6 weeks postpartum. Clinical data were sourced from routine medical records at delivery. Structured interviews at early postnatal visits and the 6-week postnatal immunisation visit provided data on infant feeding knowledge and feeding practices respectively. We measured the relationship between maternal HIV status and (i) correct infant feeding knowledge at the early postnatal visit; and (ii) infant feeding practice at 6 weeks, using Poisson and multinomial regression models, respectively.

Results

We analysed data from 1693 women with early postnatal and 471 with 6-week postnatal interviews. HIV prevalence was 47% (95% confidence interval [CI] 42, 52%). Women living with HIV were more knowledgeable than women not living with HIV on correct infant feeding recommendations (adjusted risk ratio, aRR, 1.08, p <  0.001). More women living with HIV (33%; 95% CI 26, 41%) were not breastfeeding than women not living with HIV (15%; 95% CI 11, 21%). However, among women who were currently breastfeeding their infants, fewer women living with HIV (5%; 95% CI 2, 9%) mixed fed their babies than women not living with HIV (21%; 95% CI 14, 32%). In adjusted analyses, women living with HIV were more likely to avoid breastfeeding (adjusted relative risk ratio, aRRR, 2.78, p <  0.001) and less likely to mixed feed (aRRR 0.22, p <  0.001) than women not living with HIV.

Conclusions

Many mothers in rural South Africa still do not practice exclusive breastfeeding. Women living with HIV were more knowledgeable but had lower overall uptake of breastfeeding, compared with women not living with HIV. Women living with HIV were also more likely to practice exclusive breastfeeding over mixed feeding if currently breastfeeding. Improved approaches are needed to increase awareness of correct infant feeding and exclusive breastfeeding uptake.

Cluster randomised controlled trial to determine the effect of peer delivery HIV self-testing to support linkage to HIV prevention among young women in rural KwaZulu-Natal, South Africa: a study protocol

INTRODUCTION

A cluster randomised controlled trial (cRCT) to determine whether HIV self-testing (HIVST) delivered by peers either directly or through incentivised peer-networks, could increase the uptake of antiretroviral therapy and pre-exposure prophylaxis (PrEP) among young women (18 to 24 years) is being undertaken in an HIV hyperendemic area in KwaZulu-Natal, South Africa.

METHODS AND ANALYSIS

A three-arm cRCT started mid-March 2019, in 24 areas in rural KwaZulu-Natal. Twenty-four pairs of peer navigators working with ~12 000 young people aged 18 to 30 years over a period of 6 months were randomised to: (1) incentivised-peer-networks: peer-navigators recruited participants 'seeds' to distribute up to five HIVST packs and HIV prevention information to peers within their social networks. Seeds receive an incentive (20 Rand = US$1.5) for each respondent who contacts a peer-navigator for additional HIVST packs to distribute; (2) peer-navigator-distribution: peer-navigators distribute HIVST packs and information directly to young people; (3) standard of care: peer-navigators distribute referral slips and information. All arms promote sexual health information and provide barcoded clinic referral slips to facilitate linkage to HIV testing, prevention and care services. The primary outcome is the difference in linkage rate between arms, defined as the number of women (18 to 24 years) per peer-navigators month of outreach work (/pnm) who linked to clinic-based PrEP eligibility screening or started antiretroviral, based on HIV-status, within 90 days of receiving the clinic referral slip.

ETHICS AND DISSEMINATION

This study was approved by the Institutional Review Boards at the WHO, Switzerland (Protocol ID: STAR CRT, South Africa), London School of Hygiene and Tropical Medicine, UK (Reference: 15 990-1), University of KwaZulu-Natal (BFC311/18) and the KwaZulu-Natal Department of Health (Reference: KZ_201901_012), South Africa. The findings of this trial will be disseminated at local, regional and international meetings and through peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT03751826; Pre-results.

Exploring People's Candidacy for Mobile Health-Supported HIV Testing and Care Services in Rural KwaZulu-Natal, South Africa: Qualitative Study

BACKGROUND

The use of mobile communication technologies (mHealth: mobile health) in chronic disease management has grown significantly over the years. mHealth interventions have the potential to decentralize access to health care and make it convenient, particularly in resource-constrained settings. It is against this backdrop that we aimed to codevelop (with potential users) a new generation of mobile phone-connected HIV diagnostic tests and Web-based clinical care pathways needed for optimal delivery of decentralized HIV testing, prevention, and care in low- and middle-income countries.

OBJECTIVE

The aim of this study was to understand ways in which an mHealth intervention could be developed to overcome barriers to existing HIV testing and care services and promote HIV self-testing and linkage to prevention and care in a poor, HIV hyperendemic community in rural KwaZulu-Natal, South Africa.

METHODS

A total of 54 in-depth interviews and 9 focus group discussions were conducted with potential users (including health care providers) in 2 different communities. Theoretically informed by the candidacy framework, themes were identified from the interview transcripts, manually coded, and thematically analyzed.

RESULTS

Participants reported barriers, such as fear of HIV identity, stigma, long waiting hours, clinic space, and health care workers' attitudes, as major impediments to effective uptake of HIV testing and care services. People continued to reassess their candidacy for HIV testing and care services on the basis of their experiences and how they or others were treated within the health systems. Despite the few concerns raised about new technology, mobile phone-linked HIV testing was broadly acceptable to potential users (particularly men and young people) and providers because of its privacy (individual control of HIV testing over health provider-initiated testing), convenience (individual time and place of choice for HIV testing versus clinic-based testing), and time saving.

CONCLUSIONS

Mobile phone-connected HIV testing and Web-based clinical care and prevention pathways have the potential to support access to HIV prevention and care, particularly for young people and men. Although mHealth provides a way for individuals to test their candidacy for HIV services, the barriers that can make the service unattractive at the clinic level will also need to be addressed if potential demand is to turn into actual demand.

The MONARCH intervention to enhance the quality of antenatal and postnatal primary health services in rural South Africa: protocol for a stepped-wedge cluster-randomised controlled trial

BACKGROUND

Gaps in maternal and child health services can slow progress towards achieving the Sustainable Development Goals. The Management and Optimization of Nutrition, Antenatal, Reproductive, Child Health & HIV Care (MONARCH) study will evaluate a Continuous Quality Improvement (CQI) intervention targeted at improving antenatal and postnatal health service outcomes in rural South Africa where HIV prevalence among pregnant women is extremely high. Specifically, it will establish the effectiveness of CQI on viral load (VL) testing in pregnant women who are HIV-positive and repeat HIV testing in pregnant women who are HIV-negative.

METHODS

This is a stepped-wedge cluster-randomised controlled trial (RCT) of 7 nurse-led primary healthcare clinics to establish the effect of CQI on selected routine antenatal and postnatal services. Each clinic was a cluster, with the exception of the two smallest clinics, which jointly formed one cluster. The intervention was applied at the cluster level, where staff received training on CQI methodology and additional mentoring as required. In the control exposure state, the clusters received the South African Department of Health standard of care. After a baseline data collection period of 2 months, the first cluster crossed over from control to intervention exposure state; subsequently, one additional cluster crossed over every 2 months. The six clusters were divided into 3 groups by patient volume (low, medium and high). We randomised the six clusters to the sequences of crossing over, such that both the first three and the last three sequences included one cluster with low, one with medium, and one with high patient volume. The primary outcome measures were (i) viral load testing among pregnant women who were HIV-positive, and (ii) repeat HIV testing among pregnant women who were HIV-negative. Consenting women ≥18 years attending antenatal and postnatal care during the data collection period completed outcome measures at delivery, and postpartum at three to 6 days, and 6 weeks. Data collection started on 15 July 2015. The total study duration, including pre- and post-exposure phases, was 19 months. Data will be analyzed by intention-to-treat based on first booked clinic of study participants.

DISCUSSION

The results of the MONARCH trial will establish the effectiveness of CQI in improving antenatal and postnatal clinic processes in primary care in sub-Saharan Africa. More generally, the results will contribute to our knowledge on quality improvement interventions in resource-poor settings.

TRIAL REGISTRATION

This trial was registered on 10 December 2015: www.clinicaltrials.gov, identifier NCT02626351 .

Kinetics and in Vivo Redistribution of 111Indium-Labelled Human Platelets after Intravenous Protamine Sulphate

The pathogenesis of thrombocytopenia induced by intravenous protamine sulphate was studied in six patients who underwent cardiopulmonary bypass surgery, and in three normal volunteers. Autologous platelets were labelled with 111Indium-oxine. Platelet lifespan was determined. In vivo 111In-platelet localization, organ redistribution and sites of destruction were quantitated with a scintillation camera and a computer-assisted imaging system. Protamine induced a transient thrombocytopenia, maximal 5-10 min after injection, and 30-40 min in duration. The thrombocytopenia was accompanied by a transient accumulation of platelets in the liver. The splenic platelet pool remained unaltered and no platelets accumulated in the lungs. Platelet survival, measured in two volunteers, was slightly longer than normal and fitted a linear function best. There was a severe transient neutropenia during the period of thrombocytopenia. We conclude that protamineinduced thrombocytopenia is caused by hepatic accumulation of "activated" platelets or platelet aggregates, the process is reversible, and in the two normal volunteers studied, platelet survival was not affected.

International guidance on the establishment of quality assurance programmes for radioactivity measurement in nuclear medicine

A new guidance document for the implementation of quality assurance (QA) programmes for nuclear medicine radioactivity measurement, produced by the International Atomic Energy Agency, is described. The proposed programme is based on the principles of ISO 17025 and will enable laboratories, particularly in developing countries, to provide consistent, safe and effective radioactivity measurement services to the nuclear medicine community.

Rapid nongenomic effects of aldosterone in mineralocorticoid-receptor-knockout mice

In addition to genomic effects of aldosterone, rapid nongenomic effects of steroids have been reported in various tissues that were clearly incompatible with a genomic action of aldosterone. Rapid effects of aldosterone involve second messengers such as calcium and cAMP. Specific high affinity binding sites for aldosterone have been characterized in membranes for different cells, which probably transmit those rapid steroid effects. To date, it is unclear if these binding sites are modified classical mineralocorticoid receptors (MR) or if they represent an unrelated receptor protein. The aim of the present study was to investigate whether rapid aldosterone action still occurs in the absence of the classical MR. For this purpose we used the model of MR knockout mice. Rapid effects were analyzed in skin cells, measuring intracellular calcium and cAMP levels after stimulation with aldosterone. We found that rapid effects are not only present in MR knockout mice, but that the effects are even larger than in wild-type mice cells. The results of the present study demonstrate that the classic MR is dispensable for rapid aldosterone action. The study, thus, proves that a receptor different from the classic intracellular receptor is involved in rapid aldosterone signaling.

Evaluation of microvessel density by computerised image analysis in human renal cell carcinoma. Correlation to pT category, nuclear grade, proliferative activity and occurrence of metastasis

A high microvessel density is suspected to favour tumour progression and the occurrence of metastasis. To elucidate the significance of abundant vessels for the behaviour of human renal carcinomas, the microvessel density of 110 renal cell carcinomas was correlated to pT category, nuclear grade, proliferative activity, occurrence of metastasis and relapse-free survival interval. The microvessels were quantified using CD31 immunostaining of endothelial cells and computer-aided image analysis. The rules for reproducible microvessel counting, as defined by Weidner, were strictly observed. A statistically significant relationship between the microvessel density and nuclear grade, proliferative activity, occurrence of metastasis and relapse-free survival was found; only for tumour size could no such relation be seen. Perplexingly, there is a diminution of microvessel density in association with increasing nuclear grade, proliferative activity, relapse-free survival interval and frequency of metastasis. This finding is contradictory to the hypothesis that an increasing microvessel density indicates a worsening prognosis.

A role for endothelin in bicuculline-induced neurogenic pulmonary oedema in rats

1. The possible contribution of endogenous endothelin (ET) to the pathogenesis of seizure-associated pulmonary oedema was examined in mechanically ventilated rats after intravenous bolus injection of the gamma-aminobutyric acid (GABA) antagonist, bicuculline (1.2 mg kg-1). 2. Recurrent seizure activity elicited by bicuculline injection led to rapidly developing pulmonary oedema. Within 4 min after bicuculline application (1.2 mg kg-1), arterial O2 partial pressure (PaO2) significantly dropped from 17.49 +/- 1.20 kPa to 7.51 +/- 2.21 kPa (P < 0.01) and arterial CO2 partial pressure (PaCO2) significantly increased from 4.64 +/- 0.56 kPa to 8.15 +/- 0.99 kPa (P < 0.01). Gradually a progressive acidosis developed. Moreover, mean arterial blood pressure (MABP) and end-inspiratory airway pressure (Paw) rapidly increased. 3. Concomitantly there was a time-dependent increase of big ET-1 and ET-1 levels in bronchoalveolar lavage (BAL) as determined by combined reverse phase high performance liquid chromatography (h.p.l.c.) and radioimmunoassay. BAL levels of both peptides increased up to 8 min after bicuculline injection and slowly decreased subsequently. In contrast, BAL from animals injected with vehicle did not contain detectable amounts of ET. 4. Pretreatment with the endothelin-converting enzyme inhibitor, phosphoramidon (5.4 mg kg-1, i.v.) for 5 min significantly (P < 0.001) reduced peak ET-1 levels in BAL fluid by 65.4 +/- 9.9% at 8 min after bicuculline injection. Simultaneously it afforded protection from hypoxia. PaCO2 did not increase and PaO2 decreased only slightly from 14.63 +/- 1.00 kPa to 12.97 +/- 0.61 kPa (P > 0.05) after phosphoramidon pretreatment. In contrast, vehicle-treated animals that received bicuculline showed both significant hypercapnia as well as profound hypoxia. Phosphoramidon significantly diminished the maximum increase in Paw by 76.7 +/- 12.4% (P <0.005), but only slightly affected the MABP. Phosphoramidon pretreatment had no effect on the acidosis.5. Pretreatment with the ETA receptor antagonist, BQ-123 (1 mg kg-1, i.v.), for 5 min did not affect the levels of ET-1 in the BAL fluid at 8 min after bicuculline injection but did ameliorate the development of hypoxia. No hypercapnia developed and Pa02 decreased only moderately from 16.65 +/-0.25 kPa to 14.19 +/-2.15 kPa (P>0.05) in BQ-123-treated animals. In contrast, vehicle-treated animals that received bicuculline exhibited significant hypercapnia as well as profound hypoxia. BQ-123 significantly reduced the increase in Paw by 51.3 +/- 12.8% (P < 0.01). It affected MABP only slightly and had no effect on the acidosis.6. These results suggest that ET peptides play a significant role in this model of neurogenic pulmonary oedema and may act as mediators of respiratory distress. The deleterious effects of endogenous ET in this model are primarily mediated via the ETA receptor, for they were inhibited by the ETA receptor antagonist, BQ-123. ETA receptor antagonists may therefore be of potential therapeutic value in respiratory distress.

Evidence for the formation of endothelin by lysed red blood cells from endogenous precursor

The release of endothelin from various blood cell fractions was investigated. Human as well as rat blood cell fractions homogenized by sonification were incubated in buffer for up to 60 min. Neither in platelet nor leukocyte homogenates from either species could immunoreactive endothelin be detected. In contrast, homogenates of red blood cells from both species showed a rapid and time-dependent rise of immunoreactive endothelin levels, reaching a peak at 15 min and decreasing thereafter. However, at time point 0 no immunoreactive endothelin could be detected. Reverse phase high performance liquid chromatography showed immunoreactive endothelin to consist of endothelin-1 as well as big endothelin-1. The release of immunoreactive endothelin in human and rat homogenates was concentration-dependently inhibited by the protease inhibitors, leupeptin, phosphoramidon, chymostatin and pepstatin A in order of increasing potency. Intact red blood cells did not incorporate [125I]endothelin-1 nor did they transform exogenous big endothelin-1 to endothelin-1. However, haemolysis of red blood cells with hypotonic saline (0.2%) or incubation with pore-forming staphylococcal alpha-toxin induced the release of immunoreactive endothelin into the buffer samples. Thus, apart from the indirect vasoconstrictor, haemoglobin, red blood cells can also liberate the direct vasoconstrictor, endothelin, a finding expected to be of considerable pathophysiological significance.

Establishment and characterization of two Merkel cell tumor cultures

Two Merkel cell tumor cultures (MC-MA1, MC-MA2) have been established from metastases of typical Merkel cell tumors. The mestastases in vivo were characterized by co-expression of cytokeratins 8, 18, 19, 20 and neurofilaments, presence of intermediate filament whirls, expression of synaptophysin, neuron-specific enolase, and chromogranin A, rare and weak immunostaining for plakoglobin but absence of cadherins and desmoplakins. Both cultures grow, using supplemented RPMI medium on human irradiated fibroblast feeder layers, as loosely arranged floating small aggregates. Their karyotypes are mostly hyperdiploid. The mean doubling times were about 84 h in the first 8 months and later increased. Ultrastructural and immunoelectron microscopic studies of the Merkel cell tumor cells in vitro (MC-MA1, MC-MA2) revealed sparse membrane-bound neuroendocrine granules and typical IFs that were partly arranged in paranuclear whirls and were labeled by antibodies against cytokeratins and neurofilaments. In immunocytochemical studies using antibodies to cytokeratins 8, 18, 19, and 20 and neurofilament protein NF-L, Merkel cell tumor cells in vitro showed a uniform staining appearing as paranuclear whirls and cytoplasmic fibrils as well. Double-labeling experiments showed a co-localization of both intermediate filament types in most cells. Biochemically we found cytokeratins 8, 18, 19, and 20, and NF-L in tumor cells in vitro. Immunocytochemical staining was negative for desmoplakins, various cadherins, and cell adhesion molecules, whereas plakoglobin was only rarely detectable in some Merkel cell tumor cells in vitro. By immunoluminometric assay chromogranin A was detected in cell homogenates and culture supernatants as well. Immunocytochemically, synaptophysin and neuron-specific enolase were detectable additionally in some of the cells. These established cell cultures will allow further studies devoted to the biology, differentiation, and hormone secretion of Merkel cell tumors that may also increase our knowledge about normal Merkel cells.

Effects of caloric restriction and weight loss on glycemic control, insulin release and resistance, and atherosclerotic risk in obese patients with type II diabetes mellitus

This study was designed to determine: (1) the effectiveness and safety of protein-sparing fast and gastric bypass surgery for achieving weight reduction in obese patients with type II diabetes mellitus (non-insulin-dependent diabetes mellitus); (2) the effects of these interventions on glycemic control; (3) the effects of weight loss on insulin secretion and action; and (4) the effects of treatment on atherosclerotic risk factors. Six patients consumed only a protein supplement (1.4 g/kg ideal body weight) for up to six months until a final weight below 120 percent of ideal body weight was achieved or weight loss ceased. Six patients underwent gastric bypass surgery. Both groups of patients were studied before and after treatment while consuming a balanced weight-maintaining diet. Both protein-sparing fast and gastric bypass surgery were safe and successful in the short term in producing weight loss. Both treatments improved glycemic control. Mean fasting plasma glucose values fell from 287 to 168 mg/dl (p less than 0.01). Mean total glycosylated hemoglobin values declined from 11.9 to 8.2 percent (p less than 0.01) (normal reference interval 5.85 to 8.85 percent). Patients who achieved a final weight below 125 percent of ideal body weight had significantly better post-treatment fasting plasma glucose values (130 versus 196 mg/dl, p less than 0.05) and total glycosylated hemoglobin values (6.8 versus 9.0, p less than 0.02) than those whose weight remained above 125 percent of ideal. In diet-treated patients, improved glycemic control occurred with caloric restriction alone prior to significant weight loss. Improved glycemic control was accompanied by decreased insulin resistance. Mean steady-state plasma glucose values fell from 377 to 208 mg/dl (p less than 0.008), and mean fasting insulin values fell from 31.0 to 17.0 microU/ml (p less than 0.004). Acute-phase insulin release, which was markedly impaired before treatment, did not improve even in patients who had post-treatment fasting plasma glucose values below 130 mg/dl. Significant improvements in atherosclerotic risk factors occurred. Mean high-density lipoprotein cholesterol values increased from 33.8 to 40.5 mg/dl (0.006 less than p less than 0.008), and factor VIII coagulant activity decreased from 194 to 140 percent (p less than 0.005). Serum fibrinogen also decreased (393 to 347 mg/dl, p = 0.08), although the decrease did not reach clinical significance.(ABSTRACT TRUNCATED AT 400 WORDS)

The influence of the 'collection injury' on the survival and distribution of indium-111-labeled canine platelets

The extent of the 'collection injury' sustained by platelets during labelling with In-111-oxine was investigated in three matched pairs of beagle dogs. The influence of the procedure on the survival, kinetics, in vivo distribution and fate of the labelled platelets was determined by serial blood sampling and quantitative computerized scintillation camera studies. Injured labelled platelets were removed in the matched dog acting as a biological filter. The survival, distribution and fate of the 'filtered' and 'unfiltered' platelets were compared. The mean platelet lifespan of the 'filtered' and 'unfiltered' platelets did not differ significantly, but the shape of the survival curve of the filtered platelets fitted a linear function more closely than that of the unfiltered platelets. Radioactivity in the different organs and regions was serially quantitated and expressed as a percentage of whole body radioactivity. Splenic and hepatic radioactivity of filtered and unfiltered platelets did not differ significantly at equilibrium or at the end of platelet lifespan. It is concluded that the currently employed isolation and labelling techniques for platelets are suitable for quantitative in vivo studies with a computerized scintillation camera system. The shape of platelet survival curves should, however, be interpreted with some caution as it may be influenced by these procedures.

Kinetics and sites of destruction of 111Indium-oxine-labeled platelets in idiopathic thrombocytopenic purpura: a quantitative study

Kinetics and quantification of the sites of destruction of 111-Indium-oxine-labeled autologous platelets were investigated in eight patients with idiopathic thrombocytopenic purpura. The mean platelet count was 17 +/- 9 X 10(9)/liter; platelets were separated by differential centrifugation and labeled with 5.6 +/- 2.5 MBq 111In. Whole body and organ 111In-platelet distribution was quantitated with a scintillation camera and a computer-assisted imaging system acquisition matrix. Areas of interest were selected with the computer and organ 111In-radioactivity expressed as a percentage of whole body activity. Mean platelet survival was 49.5 +/- 29.6 hr and the survival curves were exponential. Equilibrium percentage organ 111In-radioactivity was (normal values in parentheses): spleen 33.7 +/- 8.8 (31.1 +/- 10.2); liver 16.1 +/- 9.5 (13.1 +/- 1.3); thorax 22.8 +/- 3.7 (28.2 +/- 5.6). Percentage organ 111In-activity at the time when labeled platelets had disappeared from the circulation was: spleen 44.5 +/- 16.4 (40 +/- 16); liver 16.0 +/- 11.5 (32.4 +/- 7.2); thorax 19.7 +/- 6.0 (17.7 +/- 10.3). Thorax activity corresponds to bone marrow radioactivity. Three patterns of platelet sequestration were evident. Three patients had mainly splenic sequestration, two mainly hepatic sequestration, and three diffuse reticuloendothelial system sequestration with a major component of platelets destroyed in the bone marrow. Splenectomy was performed in two patients. The pattern of 111In-platelet sequestration was not predictive of response of glucocorticoid therapy or indicative of the necessity for splenectomy. Quantitative 111In-labeled autologous platelet kinetic studies provide a new tool for the investigation of platelet disorders.U

Quantification of the distribution of 111In-labelled platelets in organs

A single and practical approach to the in vivo quantification of 111indium-oxine labelled blood platelets with a scintillation camera and computer assisted imaging system was evaluated. Radioactivity of the 172 and 247 keV energies was measured in a phantom at various source distances from the collimator and the accuracy of anterior and posterior mode measurements compared with that of the geometrical mean (GM) method, with and without correction for Compton scatter (CS). Organ radioactivity, expressed as a percentage of whole body radioactivity, was determined in vivo in five baboons and the accuracy of the methods verified by post mortem quantification in the animals. Measurements in the anterior mode significantly overestimates hepatic and underestimates splenic radioactivity; posterior mode quantification reverses these results. Correction with the GM method made the accuracy and reproducibility very acceptable. Further correction for anterior-posterior attenuation and/or CS did not improve results materially. The GM method could readily be applied in five human subjects. This study showed that the GM method is an accurate and practical method for the in vivo quantification of organ and regional distribution of 111In-labelled platelets.

Kinetics and in vivo redistribution of (111)Indium-labelled human platelets after intravenous protamine sulphate

The pathogenesis of thrombocytopenia induced by intravenous protamine sulphate was studied in six patients who underwent cardiopulmonary bypass surgery, and in three normal volunteers. Autologous platelets were labelled with (111)Indium-oxine. Platelet lifespan was determined. In vivo (111)In-platelet localization, organ redistribution and sites of destruction were quantitated with a scintillation camera and a computer-assisted imaging system. Protamine induced a transient thrombocytopenia, maximal 5-10 min after injection, and 30-40 min in duration. . The thrombocytopenia was accompanied by a transient accumulation of platelets in the liver. The splenic platelet pool remained unaltered and no platelets accumulated in the lungs. Platelet survival, measured in two volunteers, was slightly longer than normal and fitted a linear function best. There was a severe transient neutropenia during the period of thrombocytopenia. We conclude that protamine-induced thrombocytopenia is caused by hepatic accumulation of "activated" platelets or platelet aggregates, the process is reversible, and in the two normal volunteers studied, platelet survival was not affected.