Defining blood hematology reference values in female pig-tailed macaques (Macaca nemestrina) using the Isolation Forest algorithm.

BACKGROUND: Pig-tailed macaques (PTMs) are commonly used as preclinical models to assess antiretroviral drugs for HIV prevention research. Drug toxicities and disease pathologies are often preceded by changes in blood hematology. To better assess the safety profile of pharmaceuticals, we defined normal ranges of hematological values in PTMs using an Isolation Forest (iForest) algorithm. METHODS: Eighteen female PTMs were evaluated. Blood was collected 1-24 times per animal for a total of 159 samples. Complete blood counts were performed, and iForest was used to analyze the hematology data to detect outliers. RESULTS: Median, IQR, and ranges were calculated for 13 hematology parameters. From all samples, 22 outliers were detected. These outliers were excluded from the reference index. CONCLUSIONS: Using iForest, we defined a normal range for hematology parameters in female PTMs. This reference index can be a valuable tool for future studies evaluating drug toxicities in PTMs.

Assessment of Anti-SARS-CoV-2 antibody levels among university students vaccinated with different COVID-19 primary and booster doses - fall 2021, Wisconsin.

BACKGROUND: University students commonly received COVID-19 vaccinations before returning to U.S. campuses in the Fall of 2021. Given likely immunologic variation among students based on differences in type of primary series and/or booster dose vaccine received, we conducted serologic investigations in September and December 2021 on a large university campus in Wisconsin to assess anti-SARS-CoV-2 antibody levels. METHODS: We collected blood samples, demographic information, and COVID-19 illness and vaccination history from a convenience sample of students. Sera were analyzed for both anti-spike (anti-S) and anti-nucleocapsid (anti-N) antibody levels using World Health Organization standardized binding antibody units per milliliter (BAU/mL). Levels were compared across categorical primary COVID-19 vaccine series received and binary COVID-19 mRNA booster status. The association between anti-S levels and time since most recent vaccination dose was estimated by mixed-effects linear regression. RESULTS: In total, 356 students participated, of whom 219 (61.5%) had received a primary vaccine series of Pfizer-BioNTech or Moderna mRNA vaccines and 85 (23.9%) had received vaccines from Sinovac or Sinopharm. Median anti-S levels were significantly higher for mRNA primary vaccine series recipients (2.90 and 2.86 log [BAU/mL], respectively), compared with those who received Sinopharm or Sinovac vaccines (1.63 and 1.95 log [BAU/mL], respectively). Sinopharm and Sinovac vaccine recipients were associated with a significantly faster anti-S decline over time, compared with mRNA vaccine recipients (P <.001). By December, 48/172 (27.9%) participants reported receiving an mRNA COVID-19 vaccine booster, which reduced the anti-S antibody discrepancies between primary series vaccine types. CONCLUSIONS: Our work supports the benefit of heterologous boosting against COVID-19. COVID-19 mRNA vaccine booster doses were associated with increases in anti-SARS-CoV-2 antibody levels; following an mRNA booster dose, students with both mRNA and non-mRNA primary series receipt were associated with comparable levels of anti-S IgG.

Learning, judgement and workforce tensions impact failure to fail in a medical postgraduate setting: A supervisor perspective.

PURPOSE: Medical training organisations have a duty to prepare medical graduates for future safe, competent practice. Decisions about underperformance are high stakes at the postgraduate level and failure to fail can occur. We aimed to explore this concept from a systems and supervisor perspective. METHOD: Supervisors of specialist physician trainees were invited to provide written feedback on failure to fail as part of a broader anonymous supervisor survey. They were provided with a trigger statement and responded in free-text format. A deductive content analysis was undertaken through the lenses of supervisor and institution. RESULTS: Of 663 supervisors who responded to the broader survey, 373 (56%) provided feedback on the failure to fail trigger statement. Analyses indicated an interplay between trainee and supervisor characteristics, and broader system elements. System elements that contributed to failure to fail trainees included lack of longitudinal monitoring and quality of assessment information. Supervisor characteristics included confident, conflicted and avoidant behaviours towards underperforming trainees. CONCLUSIONS: Individual and system challenges that contributed to failure to fail were identified in this study, and we propose a three-way tension among learning, judgement and workforce. Three potential mitigation strategies have been identified to reduce failure to fail, namely a stage-based approach to remediation, faculty development in supervisory skills and improved assessment-for-learning processes.

Phosphoinositide 3-kinase inhibitors induce DNA damage through nucleoside depletion.

We previously reported that combining a phosphoinositide 3-kinase (PI3K) inhibitor with a poly-ADP Rib polymerase (PARP)-inhibitor enhanced DNA damage and cell death in breast cancers that have genetic aberrations in BRCA1 and TP53. Here, we show that enhanced DNA damage induced by PI3K inhibitors in this mutational background is a consequence of impaired production of nucleotides needed for DNA synthesis and DNA repair. Inhibition of PI3K causes a reduction in all four nucleotide triphosphates, whereas inhibition of the protein kinase AKT is less effective than inhibition of PI3K in suppressing nucleotide synthesis and inducing DNA damage. Carbon flux studies reveal that PI3K inhibition disproportionately affects the nonoxidative pentose phosphate pathway that delivers Rib-5-phosphate required for base ribosylation. In vivo in a mouse model of BRCA1-linked triple-negative breast cancer (K14-Cre BRCA1(f/f)p53(f/f)), the PI3K inhibitor BKM120 led to a precipitous drop in DNA synthesis within 8 h of drug treatment, whereas DNA synthesis in normal tissues was less affected. In this mouse model, combined PI3K and PARP inhibition was superior to either agent alone to induce durable remissions of established tumors.

Learning relationships in community-based service-learning: a social network analysis.

BACKGROUND: Little is known about the social learning of students within community-based clinical placements and ways in which it can be supported. In an allied health service-learning program, we analysed students' learning relationships to quantify what, and from whom students learnt. METHODS: We conducted a social learning network survey in four domains of learning (clinical knowledge, procedural skills, professional development, and complex determinants of health) to explore learning relationships (ties) with other people (alters) that students (egos) formed during their placement. We quantified how different roles (supervisors, health professionals, administrators, peers, schoolteachers, and clients) contributed to the students' learning in each of the four domains. We used exponential random graph models (ERGMs) to test which relational processes contributed to the structure of the observed learning networks. RESULTS: Data was available from a complete cohort of 10 students on placement in a network of 69 members, thus providing information on 680 potential learning relations. Students engaged in similar ways in the domains of clinical knowledge, procedural skills, and professional development. Learning relations with academic supervisors were significantly more likely. Also students reported reciprocal learning relations with peers - i.e. they formed learning pairs. This effect was absent in learning networks about complex determinants of health (including socio-economic and cultural factors). Instead, local administrative staff were significantly more often the source of learning about the local contextual factors. CONCLUSIONS: Understanding the structure of student learning networks through social network analysis helps identify targeted strategies to enhance learning in community-based service-learning programs. Our findings suggest students recognised important learning from each other and from administrative personnel that is unrelated to the content of their placement. Based on this insight clinical educators could prepare students to become agentic learners, learning with each other and from sources outside their program.

Social learning in a longitudinal integrated clinical placement.

Recent research has demonstrated that longitudinal integrated placements (LICs) are an alternative mode of clinical education to traditional placements. Extended student engagement in community settings provide the advantages of educational continuity as well as increased service provision in underserved areas. Developing and maintaining LICs require a differing approach to student learning than that for traditional placements. There has been little theoretically informed empirical research that has offered explanations of which are the important factors that promote student learning in LICs and the relationships between those factors. We explored the relationship between student learning, student perceptions of preparedness for practice and student engagement, in the context of a rural LIC. We used a sequential qualitative design employing thematic, comparative and relational analysis of data from student interviews (n = 18) to understand possible processes and mechanisms of student learning in the LIC. Through the theoretical lens of social learning systems, we identified two major themes; connectivity and preparedness for practice. Connectivity described engagement and relationship building by students, across formal and informal learning experiences, interprofessional interactions, social interactions with colleagues, interaction with patients outside of the clinical setting, and the extent of integration in the wider community. Preparedness for practice, reflected students' perceptions of having sufficient depth in clinical skills, personal and professional development, cultural awareness and understanding of the health system, to work in that system. A comparative analysis compared the nature and variation of learning across students. In a relational analysis, there was a positive association between connectivity and preparedness for practice. Connectivity is a powerful enabler of students' agentic engagement, collaboration, and learning within an LIC. It is related to student perceptions of preparedness for practice. These findings provide insight for institutions wishing to develop similar programmes, by encouraging health professional educators to consider all of the potential elements of the placements, which most promote connectivity.

Dual anti-HIV mechanism of clofarabine.

BACKGROUND: HIV-1 replication kinetics inherently depends on the availability of cellular dNTPs for viral DNA synthesis. In activated CD4(+) T cells and other rapidly dividing cells, the concentrations of dNTPs are high and HIV-1 reverse transcription occurs in an efficient manner. In contrast, nondividing cells such as macrophages have lower dNTP pools, which restricts efficient reverse transcription. Clofarabine is an FDA approved ribonucleotide reductase inhibitor, which has shown potent antiretroviral activity in transformed cell lines. Here, we explore the potency, toxicity and mechanism of action of clofarabine in the human primary HIV-1 target cells: activated CD4(+) T cells and macrophages. RESULTS: Clofarabine is a potent HIV-1 inhibitor in both activated CD4(+) T cells and macrophages. Due to its minimal toxicity in macrophages, clofarabine displays a selectivity index over 300 in this nondividing cell type. The anti-HIV-1 activity of clofarabine correlated with a significant decrease in both cellular dNTP levels and viral DNA synthesis. Additionally, we observed that clofarabine triphosphate was directly incorporated into DNA by HIV-1 reverse transcriptase and blocked processive DNA synthesis, particularly at the low dNTP levels found in macrophages. CONCLUSIONS: Taken together, these data provide strong mechanistic evidence that clofarabine is a dual action inhibitor of HIV-1 replication that both limits dNTP substrates for viral DNA synthesis and directly inhibits the DNA polymerase activity of HIV-1 reverse transcriptase.

5-Azacytidine Enhances the Mutagenesis of HIV-1 by Reduction to 5-Aza-2'-Deoxycytidine.

5-Azacytidine (5-aza-C) is a ribonucleoside analog that induces the lethal mutagenesis of human immunodeficiency virus type 1 (HIV-1) by causing predominantly G-to-C transversions during reverse transcription. 5-Aza-C could potentially act primarily as a ribonucleotide (5-aza-CTP) or as a deoxyribonucleotide (5-aza-2'-deoxycytidine triphosphate [5-aza-dCTP]) during reverse transcription. In order to determine the primary form of 5-aza-C that is active against HIV-1, Illumina sequencing was performed using proviral DNA from cells treated with 5-aza-C or 5-aza-dC. 5-Aza-C and 5-aza-dC were found to induce highly similar patterns of mutation in HIV-1 in terms of the types of mutations observed, the magnitudes of effects, and the distributions of mutations at individual sequence positions. Further, 5-aza-dCTP was detected by liquid chromatography-tandem mass spectrometry in cells treated with 5-aza-C, demonstrating that 5-aza-C was a substrate for ribonucleotide reductase. Notably, levels of 5-aza-dCTP were similar in cells treated with equivalent effective concentrations of 5-aza-C or 5-aza-dC. Lastly, HIV-1 reverse transcriptase was found to incorporate 5-aza-CTPin vitroat least 10,000-fold less efficiently than 5-aza-dCTP. Taken together, these data support the model that 5-aza-C enhances the mutagenesis of HIV-1 primarily after reduction to 5-aza-dC, which can then be incorporated during reverse transcription and lead to G-to-C hypermutation. These findings may have important implications for the design of new ribonucleoside analogs directed against retroviruses.

Synergistic reduction of HIV-1 infectivity by 5-azacytidine and inhibitors of ribonucleotide reductase.

Although many compounds have been approved for the treatment of human immunodeficiency type-1 (HIV-1) infection, additional anti-HIV-1 drugs (particularly those belonging to new drug classes) are still needed due to issues such as long-term drug-associated toxicities, transmission of drug-resistant variants, and development of multi-class resistance. Lethal mutagenesis represents an antiviral strategy that has not yet been clinically translated for HIV-1 and is based on the use of small molecules to induce excessive levels of deleterious mutations within the viral genome. Here, we show that 5-azacytidine (5-aza-C), a ribonucleoside analog that induces the lethal mutagenesis of HIV-1, and multiple inhibitors of the enzyme ribonucleotide reductase (RNR) interact in a synergistic fashion to more effectively reduce the infectivity of HIV-1. In these drug combinations, RNR inhibitors failed to significantly inhibit the conversion of 5-aza-C to 5-aza-2'-deoxycytidine, suggesting that 5-aza-C acts primarily as a deoxyribonucleoside even in the presence of RNR inhibitors. The mechanism of antiviral synergy was further investigated for the combination of 5-aza-C and one specific RNR inhibitor, resveratrol, as this combination improved the selectivity index of 5-aza-C to the greatest extent. Antiviral synergy was found to be primarily due to the reduced accumulation of reverse transcription products rather than the enhancement of viral mutagenesis. To our knowledge, these observations represent the first demonstration of antiretroviral synergy between a ribonucleoside analog and RNR inhibitors, and encourage the development of additional ribonucleoside analogs and RNR inhibitors with improved antiretroviral activity.

Empowerment of young people who have a parent living with dementia: a social model perspective.

BACKGROUND: Socially constructed disablement has marginalized young people in families where a parent has younger onset dementia (YOD). This has contributed to inadequate societal support for their complex situation. Impacts on such young people include significant involvement with mental health services for themselves. In this paper, we explored the young people's lived experiences in these families and the influencing factors to enable these young people to be included and supported within their community. METHODS: In this qualitative research study, the social model of disability was used as the theoretical framework in conducting a thematic analysis of interviews with 12 participants. RESULTS: Three themes emerged; invisibility highlighting the issues of marginalization; connectivity foregrounding the engagement of young people with family, friends and their social networks, and being empowered through claiming their basic human right to receive the age appropriate support they needed. CONCLUSION: The current plight of young people living with a parent with YOD demands a fundamental shift by society in developing inclusive cross-sectorial cooperation linking service providers across youth and dementia sectors. This requires working in partnership with the service users responding to the identified needs of individual family members.

Host SAMHD1 protein promotes HIV-1 recombination in macrophages.

Template switching can occur during the reverse transcription of HIV-1. Deoxynucleotide triphosphate (dNTP) concentrations have been biochemically shown to impact HIV-1 reverse transcriptase (RT)-mediated strand transfer. Lowering the dNTP concentrations promotes RT pausing and RNA template degradation by RNase H activity of the RT, subsequently leading to strand transfer. Terminally differentiated/nondividing macrophages, which serve as a key HIV-1 reservoir, contain extremely low dNTP concentrations (20-50 nm), which results from the cellular dNTP hydrolyzing sterile α motif and histidine aspartic domain containing protein 1 (SAMHD1) protein, when compared with activated CD4(+) T cells (2-5 µm). In this study, we first observed that HIV-1 template switching efficiency was nearly doubled in human primary macrophages when compared with activated CD4(+) T cells. Second, SAMHD1 degradation by viral protein X (Vpx), which elevates cellular dNTP concentrations, decreased HIV-1 template switching efficiency in macrophages to the levels comparable with CD4(+) T cells. Third, differentiated SAMHD1 shRNA THP-1 cells have a 2-fold increase in HIV-1 template switching efficiency. Fourth, SAMHD1 degradation by Vpx did not alter HIV-1 template switching efficiency in activated CD4(+) T cells. Finally, the HIV-1 V148I RT mutant that is defective in dNTP binding and has DNA synthesis delay promoted RT stand transfer when compared with wild type RT, particularly at low dNTP concentrations. Here, we report that SAMHD1 regulation of the dNTP concentrations influences HIV-1 template switching efficiency, particularly in macrophages.

Host factor SAMHD1 restricts DNA viruses in non-dividing myeloid cells.

SAMHD1 is a newly identified anti-HIV host factor that has a dNTP triphosphohydrolase activity and depletes intracellular dNTP pools in non-dividing myeloid cells. Since DNA viruses utilize cellular dNTPs, we investigated whether SAMHD1 limits the replication of DNA viruses in non-dividing myeloid target cells. Indeed, two double stranded DNA viruses, vaccinia and herpes simplex virus type 1, are subject to SAMHD1 restriction in non-dividing target cells in a dNTP dependent manner. Using a thymidine kinase deficient strain of vaccinia virus, we demonstrate a greater restriction of viral replication in non-dividing cells expressing SAMHD1. Therefore, this study suggests that SAMHD1 is a potential innate anti-viral player that suppresses the replication of a wide range of DNA viruses, as well as retroviruses, which infect non-dividing myeloid cells.

Anti-HIV host factor SAMHD1 regulates viral sensitivity to nucleoside reverse transcriptase inhibitors via modulation of cellular deoxyribonucleoside triphosphate (dNTP) levels.

Newly identified anti-HIV host factor, SAMHD1, restricts replication of lentiviruses such as HIV-1, HIV-2, and simian immunodeficiency virus in macrophages by enzymatically hydrolyzing and depleting cellular dNTPs, which are the substrates of viral DNA polymerases. HIV-2 and some simian immunodeficiency viruses express viral protein X (VPX), which counteracts SAMHD1 and elevates cellular dNTPs, enhancing viral replication in macrophages. Because nucleoside reverse transcriptase inhibitors (NRTIs), the most commonly used anti-HIV drugs, compete against cellular dNTPs for incorporation into proviral DNA, we tested whether SAMHD1 directly affects the efficacy of NRTIs in inhibiting HIV-1. We found that reduction of SAMHD1 levels with the use of virus-like particles expressing Vpx- and SAMHD1-specific shRNA subsequently elevates cellular dNTPs and significantly decreases HIV-1 sensitivity to various NRTIs in macrophages. However, virus-like particles +Vpx treatment of activated CD4(+) T cells only minimally reduced NRTI efficacy. Furthermore, with the use of HPLC, we could not detect SAMHD1-mediated hydrolysis of NRTI-triphosphates, verifying that the reduced sensitivity of HIV-1 to NRTIs upon SAMHD1 degradation is most likely caused by the elevation in cellular dNTPs.

Restricted 5'-end gap repair of HIV-1 integration due to limited cellular dNTP concentrations in human primary macrophages.

HIV-1 proviral DNA integration into host chromosomal DNA is only partially completed by the viral integrase, leaving two single-stranded DNA gaps with 5'-end mismatched viral DNA flaps. It has been inferred that these gaps are repaired by the cellular DNA repair machinery. Here, we investigated the efficiency of gap repair at integration sites in different HIV-1 target cell types. First, we found that the general gap repair machinery in macrophages was attenuated compared with that in dividing CD4(+) T cells. In fact, the repair in macrophages was heavily reliant upon host DNA polymerase ß (Pol ß). Second, we tested whether the poor dNTP availability found in macrophages is responsible for the delayed HIV-1 proviral DNA integration in this cell type because the Km value of Pol ß is much higher than the dNTP concentrations found in macrophages. Indeed, with the use of a modified quantitative AluI PCR assay, we demonstrated that the elevation of cellular dNTP concentrations accelerated DNA gap repair in macrophages at HIV-1 proviral DNA integration sites. Finally, we found that human monocytes, which are resistant to HIV-1 infection, exhibited severely restricted gap repair capacity due not only to the very low levels of dNTPs detected but also to the significantly reduced expression of Pol ß. Taken together, these results suggest that the low dNTP concentrations found in macrophages and monocytes can restrict the repair steps necessary for HIV-1 integration.

Professionally led support groups for people living with advanced or metastatic cancer: a systematic scoping review of effectiveness and factors critical to implementation success within real-world healthcare and community settings.

PURPOSE: To examine the effectiveness of professionally led support groups for people with advanced or metastatic cancer, and identify factors critical to implementation success within real-world settings. METHODS: Databases (MEDLINE; PsychINFO; CINAHL) and grey literature were searched for empirical publications and evaluations. Articles were screened for eligibility and data systematically extracted, charted and summarised using a modified scoping review methodology. Implementation factors were mapped using Proctor's implementation framework and the Consolidated Framework for Implementation Research 2.0. RESULTS: A total of 1691 publications were identified; 19 were eligible for inclusion (8 randomised controlled trials, 7 qualitative studies, 2 cohort studies, 2 mixed methods studies). Most (n=18) studies focused on tumour-specific support groups. Evidence supported professionally led support groups in reducing mood disturbances (n=5), distress (i.e. traumatic stress, depression) (n=4) and pain (n=2). Other benefits included social connectedness (n=6), addressing existential distress (n=5), information and knowledge (n=6), empowerment and sense of control (n=2), relationships with families (n=2) and communication with health professionals (n=2). Thirteen studies identified factors predicting successful adoption, implementation or sustainment, including acceptability (n=12; 63%), feasibility (n=6; 32%) and appropriateness (n=1; 5%). Key determinants of successful implementation included group leaders' skills/experience, mode of operation, travelling distance, group composition and membership and resourcing. CONCLUSIONS: Professionally led tumour-specific support groups demonstrate effectiveness in reducing mood disturbances, distress and pain among patients. Successful implementation hinges on factors such as leadership expertise, operational methods and resource allocation. IMPLICATIONS FOR CANCER SURVIVORS: Professionally led support groups may fill an important gap in supportive care for people with advanced or metastatic cancer.

Longitudinal integrated rural placements: a social learning systems perspective.

OBJECTIVES: There is currently little theoretically informed exploration of how non-traditional clinical placement programmes that are longitudinal, immersive, based on community-engaged education principles and located in rural and remote settings may contribute to medical student learning. This paper aims to theoretically illustrate the pedagogical and socio-cultural underpinnings of student learning within a longitudinal, integrated, community-engaged rural placement. METHODS: Data collected using semi-structured interviews with medical students, their supervisors and other health clinicians participating in a longitudinal rural placement programme were analysed using framework analysis. Data interpretation was informed by the theory of social learning systems (SLSs). RESULTS: In a longitudinal, rural clinical placement students participate in an SLS with distinct yet interrelated learning spaces that contain embedded communities of practice (CoPs). These spaces are characterised by varying degrees of formality, membership and interaction, and different learning opportunities and experiences. They are situated within and shaped by a unique geography of place comprising the physical and social features of the placement setting. Within these learning spaces, students acquire clinical knowledge, skills and competencies, professional attitudes, behaviours and professional values. The process of connectivity helps explain how students access and cross the boundaries between these learning spaces and develop a more complex sense of professional identity. CONCLUSIONS: Longitudinal, integrated clinical placement models can be understood as SLSs comprising synergistic and complementary learning spaces, in which students engage and participate in multiple CoPs. This occurs in a context shaped by unique influences of the geography of place. This engagement provides for a range of student learning experiences, which contribute to clinical learning and the development of a more sophisticated professional identity. A range of pedagogical and practical strategies can be embedded within this SLS to enhance student learning.

What factors in rural and remote extended clinical placements may contribute to preparedness for practice from the perspective of students and clinicians?

BACKGROUND: Community-based rural education opportunities have expanded in Australia, attracting more medical students to placements in rural and remote settings. AIM: To identify the factors in an integrated, community-engaged rural placement that may contribute to preparedness for practice (P4P) from the perspective of students and clinicians. METHOD: Forty-two semi-structured interviews with medical students, supervisors and clinicians analysed thematically. RESULTS: Opportunities for clinical learning, personal and professional development and cultural awareness were reported by students and clinicians as key factors that contribute to P4P. Potential barriers in rural and remote settings included geographical and academic isolation, perceived educational risk and differing degrees of program engagement. CONCLUSIONS: A longitudinal clinical placement in a rural setting may enable development of enhanced competencies leading to P4P. A rural setting can provide a unique experience through hands-on learning, enhanced personal and professional development opportunities and observation of the cultural and contextual impact on health.

Pharmacokinetic Study of Islatravir and Etonogestrel Implants in Macaques.

The prevention of HIV and unintended pregnancies is a public health priority. Multi-purpose prevention technologies capable of long-acting HIV and pregnancy prevention are desirable for women. Here, we utilized a preclinical macaque model to evaluate the pharmacokinetics of biodegradable ε-polycaprolactone implants delivering the antiretroviral islatravir (ISL) and the contraceptive etonogestrel (ENG). Three implants were tested: ISL-62 mg, ISL-98 mg, and ENG-33 mg. Animals received one or two ISL-eluting implants, with doses of 42, 66, or 108 µg of ISL/day with or without an additional ENG-33 mg implant (31 µg/day). Drug release increased linearly with dose with median [range] plasma ISL levels of 1.3 [1.0-2.5], 1.9 [1.2-6.3] and 2.8 [2.3-11.6], respectively. The ISL-62 and 98 mg implants demonstrated stable drug release over three months with ISL-triphosphate (ISL-TP) concentr54ations in PBMCs above levels predicted to be efficacious for PrEP. Similarly, ENG implants demonstrated sustained drug release with median [range] plasma ENG levels of 495 [229-1110] pg/mL, which suppressed progesterone within two weeks and showed no evidence of altering ISL pharmacokinetics. Two of the six ISL-98 mg implants broke during the study and induced implant-site reactions, whereas no reactions were observed with intact implants. We show that ISL and ENG biodegradable implants are safe and yield sufficient drug levels to achieve prevention targets. The evaluation of optimized implants with increased mechanical robustness is underway for improved durability and vaginal efficacy in a SHIV challenge model.

A longitudinal integrated placement and medical students' intentions to practise rurally.

CONTEXT: Integrated longitudinal rural placements are designed to promote favourable student attitudes towards and facilitate return to rural practice upon graduation. We explored the impact of an integrated placement on medical students' attitudes towards rural practice. METHODS: Data were available from interviews with 10 medical students, 15 clinical supervisors and teachers, three community health staff, and focus groups made up of medical students. Socio-cognitive career theory gave insight into the personal, contextual and experiential factors, as well as the career barriers, that influence students' rural practice intentions. Framework analysis was used to develop a thematic framework illustrating the key findings. RESULTS: The longitudinal placement enabled students to achieve personal goals, and enhanced self-efficacy beliefs and orientation towards the complex personal and professional demands of rural practice. The informal curriculum, including multifaceted interactions with patients and their families, clinical teachers and other health care staff, was a vital experiential component. Students assimilated these rich experiences into their practice and evolving notions of professional identity as rural practitioners. Some students had little intention of practising rurally, partly as a result of contextual barriers such as geographic isolation, family and relationship needs, restricted postgraduate training opportunities and limited opportunities for specialist practice. CONCLUSIONS: The richness of the informal curriculum in a longitudinal rural placement powerfully influenced students' intentions to practise rurally. It provided an important context for learning and evolving notions of professionalism and rural professional identity. This richness could be reinforced by developing formal curricula using educational activities based around service-led and interprofessional learning. To overcome the contextual barriers, the rural workforce development model needs to focus on socialising medical students into rural and remote medicine. More generic issues include student selection, further expansion of structured vocational training pathways that vertically integrate with longitudinal rural placements and the maintenance of rurally focused support throughout postgraduate training.

Distinct Antiretroviral Mechanisms Elicited by a Viral Mutagen.

5-aza-cytidine (5-aza-C) has been shown to be a potent human immunodeficiency virus type 1 (HIV-1) mutagen that induces G-to-C hypermutagenesis by incorporation of the reduced form (i.e., 5-aza-dC, 5-aza-dCTP). Evidence to date suggests that this lethal mutagenesis is the primary antiretroviral mechanism for 5-aza-C. To investigate the breadth of application of 5-aza-C as an antiretroviral mutagen, we have conducted a comparative, parallel analysis of the antiviral mechanism of 5-aza-C between HIV-1 and gammaretroviruses - i.e., murine leukemia virus (MuLV) and feline leukemia virus (FeLV). Intriguingly, in contrast to the hallmark G-to-C hypermutagenesis observed with HIV-1, MuLV and FeLV did not reveal the presence of a significant increase in mutational burden, particularly that of G-to-C transversion mutations. The effect of 5-aza-dCTP on DNA synthesis revealed that while HIV-1 RT was not inhibited by 5-aza-dCTP even at 100 µM, 5-aza-dCTP was incorporated and significantly inhibited MuLV RT, generating pause sites and reducing the fully extended product. 5-aza-dCTP was found to be incorporated into DNA by MuLV RT or HIV-1 RT, but only acted as a non-obligate chain terminator for MuLV RT. This biochemical data provides an independent line of experimental evidence in support of the conclusion that HIV-1 and MuLV have distinct primary mechanisms of antiretroviral action with 5-aza-C. Taken together, our data provides striking evidence that an antiretroviral mutagen can have strong potency via distinct mechanisms of action among closely related viruses, unlinking antiviral activity from antiviral mechanism of action.