Human P450 CYP17A1: Control of Substrate Preference by Asparagine 202

CYP17A1 is a key steroidogenic enzyme known to conduct several distinct chemical transformations on multiple substrates. In its hydroxylase activity, this enzyme adds a hydroxyl group at the 17α position of both pregnenolone and progesterone at approximately equal rates. However, the subsequent 17,20 carbon–carbon scission reaction displays variable substrate specificity in the numerous CYP17A1 isozymes operating in vertebrates, manifesting as different Kd and kcat values when presented with 17α-hydroxypregnenlone (OHPREG) versus 17α-hydroxyprogesterone (OHPROG). Here we show that the identity of the residue at position 202 in human CYP17A1, thought to form a hydrogen bond with the A-ring alcohol substituent on the pregnene- nucleus, is a key driver of this enzyme’s native preference for OHPREG. Replacement of asparagine 202 with serine completely reverses the preference of CYP17A1, more than doubling the rate of turnover of the OHPROG to androstenedione reaction and substantially decreasing the rate of formation of dehydroepiandrosterone from OHPREG. In a series of resonance Raman experiments, it was observed that, in contrast with the case for the wild-type protein, in the mutant the 17α alcohol of OHPROG tends to form a H-bond with the proximal rather than terminal oxygen of the oxy–ferrous complex. When OHPREG was a substrate, the mutant enzyme was found to have a H-bonding interaction with the proximal oxygen that is substantially weaker than that of the wild type. These results demonstrate that a single-point mutation in the active site pocket of CYP17A1, even when far from the heme, has profound effects on steroidogenic selectivity in androgen biosynthesis

The impact of climate change on maternal and child health

It can be argued that there are three colliding pandemics that are currently affecting the planet and its people: COVID-19, global inequities and climate change. Regrettably, these are all the result of human action or inaction and are preventable. The United Nations Conference of the Parties (COP26), held in November 2021 in Glasgow, addressed some of these issues. Prince Charles called this meeting the ‘last chance saloon to save the planet.’ e main objective of COP26 was to reduce global heating and limit global warming to the target maximum temperature of 1.5-degree Celsius above preindustrial levels. According to the National Aeronautics and Space Administration (NASA), since the late 19th century, the earth surface temperature rose by.18 degrees Celsius, caused by increased carbon dioxide and other emissions into the atmosphere, with the years 2016 and 2020 being tied as the warmest years on record. However, many, including a group of scientists called ‘Scientist Rebellion’ were not convinced that COP26 would make any di erence to the warming of the planet. President of COP26, Alok Sharma admitted that the objective of the conference was not reached but remained cautiously optimistic: “We can now say with credibility that we have kept 1.5 degrees alive. But its pulse is weak and it will only survive if we keep our promises and translate commitments into rapid action”.https://www.obstetricsandgynaecologyforum.comam2023Obstetrics and Gynaecolog

Conversions of Tricyclic Antidepressants and Antipsychotics with Selected P450s from Sorangium cellulosum So ce56 s

ABSTRACT Human cytochromes P450 (P450s) play a major role in the biotransformation of drugs. The generated metabolites are important for pharmaceutical, medical, and biotechnological applications and can be used for derivatization or toxicological studies. The availability of human drug metabolites is restricted and alternative ways of production are requested. For this, microbial P450s turned out to be a useful tool for the conversion of drugs and related derivatives. Here, we used 10 P450s from the myxobacterium Sorangium cellulosum So ce56, which have been cloned, expressed, and purified. The P450s were investigated concerning the conversion of the antidepressant drugs amitriptyline, clomipramine, imipramine, and promethazine; the antipsychotic drugs carbamazepine, chlorpromazine, and thioridazine, as well as their precursors, iminodibenzyl and phenothiazine. Amitriptyline, chlorpromazine, clomipramine, imipramine, and thioridazine are efficiently converted during the in vitro reaction and were chosen to upscale the production by an Escherichia coli-based whole-cell bioconversion system. Two different approaches, a whole-cell system using M9CA medium and a system using resting cells in buffer, were used for the production of sufficient amounts of metabolites for NMR analysis. Amitriptyline, clomipramine, and imipramine are converted to the corresponding 10-hydroxylated products, whereas the conversion of chlorpromazine and thioridazine leads to a sulfoxidation in position 5. It is shown for the first time that myxobacterial P450s are efficient to produce known human drug metabolites in a milligram scale, revealing their ability to synthesize pharmaceutically important compounds

Elimination of mother-to-child transmission of HIV in South Africa : rapid scale-up using quality improvement

BACKGROUND. South Africa (SA) is committed to achieving the goal of eliminating mother-to-child transmission (MTCT) of HIV by 2015. To achieve this, universal coverage of quality antenatal, labour, delivery and postnatal services for all women has to be attained. Over the past decade, the prevention of mother-to-child transmission (PMTCT) programme has been scaled up to reach all healthcare facilities in the country. However, challenges persist in achieving 100% coverage and access to the programme. OBJECTIVES. We describe the process undertaken by the National Department of Health (NDoH), in collaboration with partners, to develop, implement and monitor a data-driven intervention to improve facility, district, provincial and national PMTCT-related performance. METHODS. Between 2011 and 2013, the NDoH developed and implemented an intervention using data-driven participatory processes to understand facility-level bottlenecks to optimise PMTCT implementation and to scale up priority PMTCT actions nationally. RESULTS. There was remarkable improvement across all key indicators in the PMTCT cascade over the 3 years 2011 - 2013. Simple monitoring tools such as a visual dashboard and data for action reports were successfully used to improve the performance of the PMTCT programme across SA. MTCT has shown a significant downward trend. CONCLUSIONS. It is feasible to implement district-level, data-driven quality improvement processes at a national scale to improve the performance of the PMTCT programme at the local level.http://www.samj.org.zaam201

Provider and female client economic costs of integrated sexual and reproductive health and HIV Services in Zimbabwe

A retrospective facility-based costing study was undertaken to estimate the comparative cost per visit of five integrated sexual and reproductive health and HIV (human immuno-deficiency virus) services (provider perspective) within five clinic sites. These five clinics were part of four service delivery models: Non-governmental-organisation (NGO) directly managed model (Chitungwiza and New Africa House sites), NGO partner managed site (Mutare site), private-public-partnership (PPP) model (Chitungwiza Profam Clinic), and NGO directly managed outreach (operating from New Africa House site. In addition client cost exit interviews (client perspective) were conducted among 856 female clients exiting integrated services at three of the sites. Our costing approach involved first a facility bottom-up costing exercise (February to April 2015), conducted to quantify and value each resource input required to provide individual SRH and HIV services. Secondly overhead financial expenditures were allocated top-down from central office to sites and then respective integrated service based on pre-defined allocation factors derived from both the site facility observations and programme data for the prior 12 months. Costs were assessed in 2015 United States dollars (USD). Costs were assessed for HIV testing and counselling, screening and treatment of sexually transmitted infections, tuberculosis screening with smear microscopy, family planning, and cervical cancer screening and treatment employing visual inspection with acetic acid and cervicography and cryotherapy. Variability in costs per visit was evident across the models being highest for cervical cancer screening and cryotherapy (range: US$6.98 - US$49.66). HIV testing and counselling showed least variability (range; US$10.96 - US$16.28). In general the PPP model offered integrated services at the lowest unit costs whereas the partner managed site was highest. Significant client costs remain despite availability of integrated sexual and reproductive health and HIV services free of charge in our Zimbabwe study setting. Situating services closer to communities, incentives, transport reimbursements, reducing waiting times and co-location of sexual and reproductive health and HIV services may help minimise impact of client costs

Health personnel retention strategies in a peri-urban community: an exploratory study on Epworth, Zimbabwe

BACKGROUND : The need to retain health personnel is a policy challenge undermining health system reform of the 21st century. The need to resolve this global health workforce crisis resulted in the First Global Forum on Human Resources for Health in 2008 from which the Kampala Declaration and Agenda for Global Action was formulated. However, whilst there have been several studies exploring the retention of health personnel towards this end, available literature does not provide a detailed narrative on strategies used in peri-urban communities. The aim of this study was to explore retention strategies implemented in a Zimbabwean peri-urban community between 2009 and 2014 and implications for peri-urban communities towards the health system reform agenda. METHODS : The study was carried out in Epworth, a peri-urban community in Harare, Zimbabwe. The research design was a cross-sectional survey, in which qualitative methods were used in sampling, data collection, reporting and analysis. Qualitative tools were used to collect data through in-depth interviews with purposively selected health personnel managers at 10 local clinics and sample interviews with purposively selected healthcare workers who included registered general nurses, state-certified nurses, midwives, environmental health technicians, nurse aids and community health volunteers at each clinic. Two focus group discussions were carried out with community health volunteers. Qualitative data was subjected to thematic analysis, with coding being performed manually. RESULTS : A programme-specific strategic partnership between the government and donor community contributed towards the mobilisation of more health personnel, health facilities, worker development and remuneration. To complement this, the Ministry of Health intervened through the review and payment of salaries, support towards post-basic training and development, and protection. The local board, mission and donors contributed through the payment of top-up allowances and provision of non-monetary incentives. CONCLUSIONS : The review of salaries, engagement of international strategic partners, payment of top-up allowances, support towards post-basic training and development, mobilisation of more health personnel, non-monetary incentives and healthcare worker protection were critical towards the retention of health personnel in the Epworth peri-urban community between 2009 and 2014.We are most grateful to the African Doctoral Dissertation Research Fellowship Award (ADDRF 2015-2017 ADF 002) offered by the African Population and Health Research Centre in partnership with the International Development Research Centre which made this research possible. We are also grateful to the University of Pretoria Postgraduate Research Bursary (10443925) which also made this study possible.http://www.human-resources-health.comam2016School of Health Systems and Public Health (SHSPH

Feasibility of achieving the 2025 WHO global tuberculosis targets in South Africa, China, and India: a combined analysis of 11 mathematical models.

BACKGROUND: The post-2015 End TB Strategy proposes targets of 50% reduction in tuberculosis incidence and 75% reduction in mortality from tuberculosis by 2025. We aimed to assess whether these targets are feasible in three high-burden countries with contrasting epidemiology and previous programmatic achievements. METHODS: 11 independently developed mathematical models of tuberculosis transmission projected the epidemiological impact of currently available tuberculosis interventions for prevention, diagnosis, and treatment in China, India, and South Africa. Models were calibrated with data on tuberculosis incidence and mortality in 2012. Representatives from national tuberculosis programmes and the advocacy community provided distinct country-specific intervention scenarios, which included screening for symptoms, active case finding, and preventive therapy. FINDINGS: Aggressive scale-up of any single intervention scenario could not achieve the post-2015 End TB Strategy targets in any country. However, the models projected that, in the South Africa national tuberculosis programme scenario, a combination of continuous isoniazid preventive therapy for individuals on antiretroviral therapy, expanded facility-based screening for symptoms of tuberculosis at health centres, and improved tuberculosis care could achieve a 55% reduction in incidence (range 31-62%) and a 72% reduction in mortality (range 64-82%) compared with 2015 levels. For India, and particularly for China, full scale-up of all interventions in tuberculosis-programme performance fell short of the 2025 targets, despite preventing a cumulative 3·4 million cases. The advocacy scenarios illustrated the high impact of detecting and treating latent tuberculosis. INTERPRETATION: Major reductions in tuberculosis burden seem possible with current interventions. However, additional interventions, adapted to country-specific tuberculosis epidemiology and health systems, are needed to reach the post-2015 End TB Strategy targets at country level. FUNDING: Bill and Melinda Gates Foundation

Original Article

The pancreas taken from the frog (Rana nigromaculata) was fixed in 1% OsO_4 and sliced into ultrathin sections for electron microscopic studies. The following observations were made: 1. A great \u27number of minute granules found in the cytoplasm of a pancreatic cell were called the microsomes, which were divided into two types, the C-microsome and S-microsome. 2. Electron microsopic studies of the ergastoplasm showed that it is composed of the microsome granules and A-substance. The microsomes were seen embedded in the A-substance which was either filamentous or membranous. The membranous structure, which was called the Am-membrane, was seen to form a sac, with a cavity of varying sizes, or to form a lamella. 3. The Am-membrane has close similarity to α-cytomembrane of Sjostrand, except that the latter is rough-surfaced. It was deduced that the Am-membrane, which is smooth-surfaced, might turn into the rough-surfaced α-cytomembrane. 4. There was the Golgi apparatus in the supranuclear region of a pancreatic cell. It consisted of the Golgi membrane, Golgi vacuole and. Golgi vesicle. 5. The mitochondria of a pancreatic cell appeared like long filaments, and some of them were seen to ramify. 6. The membrane of mitochondria, i. e. the limiting membrane, consisted of the Ammembrane. The mitochondria contained a lot of A-substances, as well as the C-microsomes and S-microsomes. When the mitochondria came into being, there appeared inside them chains of granules, which appeared like strips of beads, as the outgrowths of the A-substance and the microsome granules attached to the Am-membrane. They are the so-called cristae mitochondriales. 7. The secretory granules originate in the microsomes. They came into being when the microsomes gradually thickened and grew in size as various substances became adhered to them. Some of the secretory granules were covered with a membrane and appeared like what they have called the intracisternal granule of Palade.It seemed that this was a phenomenon attendant upon the dissolution and liqutefaction of the secretory granule. 8. Comparative studies were made of the ergastoplasm of the pancreatic cells from the frogs in hibernation, the frogs artificially hungered, the frogs which were given food after a certain period of fasting, the frogs to which pilocarpine was given subcutaneously, and the very young, immature frogs. The studies revealed that the ergastoplasm of the pancreatic cells greatly varied in form with the difference in nutritive condition and with different developmental stages of the cell. The change in form and structure occured as a result of transformation of the microsomes and A-substance. The ergastoplasm, even after it has come into being, might easily be inactivated if nutrition is defective. The ergastoplasm is concerned in the secretory mechanism, which is different from the secretory phenomenon of the secretory granules. It would seem that structurally the mitochondria have no direct relation to this mechanism

Cost and impact of scaling up interventions to save lives of mothers and children: taking South Africa closer to MDGs 4 and 5

Background: South Africa has made substantial progress on child and maternal mortality, yet many avoidable deaths of mothers and children still occur. This analysis identifies priority interventions to be scaled up nationally and projects the potential maternal and child lives saved. Design: We modelled the impact of maternal, newborn and child interventions using the Lives Saved Tools Projections to 2015 and used realistic coverage increases based on expert opinion considering recent policy change, financial and resource inputs, and observed coverage change. A scenario analysis was undertaken to test the impact of increasing intervention coverage to 95%. Results: By 2015, with realistic coverage, the maternal mortality ratio (MMR) can reduce to 153 deaths per 100,000 and child mortality to 34 deaths per 1,000 live births. Fifteen interventions, including labour and delivery management, early HIV treatment in pregnancy, prevention of mother-to-child transmission and handwashing with soap, will save an additional 9,000 newborns and children and 1,000 mothers annually. An additional US$370 million (US$7 per capita) will be required annually to scale up these interventions. When intervention coverage is increased to 95%, breastfeeding promotion becomes the top intervention, the MMR reduces to 116 and the child mortality ratio to 23. Conclusions: The 15 interventions identified were adopted by the National Department of Health, and the Health Minister launched a campaign to encourage Provincial Health Departments to scale up coverage. It is hoped that by focusing on implementing these 15 interventions at high quality, South Africa will reach Millennium Development Goal (MDG) 4 soon after 2015 and MDG 5 several years later. Focus on HIV and TB during early antenatal care is essential. Strategic gains could be realised by targeting vulnerable populations and districts with the worst health outcomes. The analysis demonstrates the usefulness of priority setting tools and the potential for evidence-based decision making in the health sector