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Purpose: Subcutaneously or intramuscularly administered biodegradable microsphere formulations have been successfully exploited in the management of chronic conditions for over two decades, yet mechanistic understanding of the impact of formulation attributes on in vivo absorption rate from such systems is still in its infancy. Methods: Suspension formulation physicochemical attributes may impact particulate deposition in subcutaneous (s.c.) tissue. Hence, the utility of synchrotron X-ray micro-computed tomography (μCT) for assessment of spatial distribution of suspension formulation components (PLG microspheres and vehicle) was evaluated in a porcine s.c. tissue model. Optical imaging of dyed vehicle and subsequent microscopic assessment of microsphere deposition was performed in parallel to compare the two approaches. Results: Our findings demonstrate that synchrotron μCT can be applied to the assessment of microsphere and vehicle distribution in s.c. tissue, and that microspheres can also be visualised in the absence of contrast agent using this approach. The technique was deemed superior to optical imaging of macrotomy for the characterisation of microsphere deposition owing to its non-invasive nature and relatively rapid data acquisition time. Conclusions: The method outlined in this study provides a proof of concept feasibility for μCT application to determining the vehicle and suspended PLG microspheres fate following s.c. injection. A potential application for our findings is understanding the impact of injection, device and formulation variables on initial and temporal depot geometry in pre-clinical or ex-vivo models that can inform product design. [ABSTRACT FROM AUTHOR]

Relationship agreements are important for HIV prevention among gay and bisexual men (GBM) in relationships, with research earlier in the HIV epidemic often finding that agreements specified monogamy or condom use with casual partners. There is evidence that HIV pre-exposure prophylaxis (PrEP) has shifted sexual practices among some men in relationships, such as allowing condomless sex with casual partners, but there has been little attention paid to relationship agreements among GBM who use PrEP. In this paper, we analyzed national, Australian, cross-sectional data from an online survey completed by non-HIV-positive GBM in 2021 (N = 1,185). Using logistic regression, we identified demographic characteristics, sexual practices and the types of relationship agreement that were associated with PrEP use among GBM in relationships. Using Pearson's chi-squared tests, we explored whether PrEP users in relationships reported similar sexual practices to PrEP users not in relationships. PrEP use among GBM in relationships was independently associated with older age, identifying as gay, being in a non-monogamous relationship, having a spoken (explicit) relationship agreement, having a primary HIV-negative partner taking PrEP or a primary partner living with HIV, reporting recent condomless casual sex, reporting an STI diagnosis in the past year, and knowing at least one other PrEP user. We found that PrEP users in relationships had similar sexual practices to PrEP users not in relationships. GBM in relationships who have casual sex and who meet PrEP suitability criteria may be good candidates for PrEP. Our findings suggest that explicit relationship agreements remain important for HIV prevention, and they support PrEP use among GBM in relationships. [ABSTRACT FROM AUTHOR]

We examined depression and anxiety prior to and during COVID-19 restrictions in Australian gay and bisexual men (GBM). In an online cohort, a COVID-19-focused survey was conducted in April 2020. During 2019 and in April 2020, 664 GBM completed the Patient Health Questionnaire (PHQ-9, measuring depression) and Generalized Anxiety Disorder Assessment (GAD-7, measuring anxiety). Increased depression and anxiety were defined as a ≥ 5 point increase on the respective scales. Mean PHQ-9 and GAD-7 scores increased between 2019 and 2020 (PHQ-9: from 5.11 in 2019 to 6.55 in 2020; GAD-7: from 3.80 in 2019 to 4.95 in 2020). The proportion of participants with moderate-severe depression (PHQ-9 ≥ 10) increased from 18.8% (n = 125) to 25.5% (n = 169), while the proportion of participants with moderate-severe anxiety (GAD-7 ≥ 10) increased from 12.7% (n = 84) to 17.3% (n = 115). Almost one-quarter of participants (n = 158, 23.8%) had increased depression; in these men, mean PHQ-9 increased from 2.49 in 2019 to 11.65 in 2020 (p < 0.001). One-in-five (20.6%) participants (n = 137) had increased anxiety; among these men, mean GAD-7 increased from 2.05 in 2019 to 10.22 in 2020 (p < 0.001). Increases were associated with concerns about job security, reduction in social and sexual connections and opportunities, and being personally concerned about COVID-19 itself. COVID-19 appeared to have a sudden and pronounced impact on depression and anxiety in Australian GBM, with a significant minority showing sharp increases. Ongoing monitoring is required to determine longer-term impacts and GBM need access to appropriate and sensitive supports both during and after the COVID-19 pandemic. [ABSTRACT FROM AUTHOR]