[Carboxyl-11 C]Labelling of Four High-Affinity cPLA2α Inhibitors and Their Evaluation as Radioligands in Mice by Positron Emission Tomography.

Cytosolic phospholipase A2α (cPLA2α) may play a critical role in neuropsychiatric and neurodegenerative disorders associated with oxidative stress and neuroinflammation. An effective PET radioligand for imaging cPLA2α in living brain might prove useful for biomedical research, especially on neuroinflammation. We selected four high-affinity (IC50 2.1-12 nm) indole-5-carboxylic acid-based inhibitors of cPLA2α, namely 3-isobutyryl-1-(2-oxo-3-(4-phenoxyphenoxy)propyl)-1H-indole-5-carboxylic acid (1); 3-acetyl-1-(2-oxo-3-(4-(4-(trifluoromethyl)phenoxy)phenoxy)propyl)-1H-indole-5-carboxylic acid (2); 3-(3-methyl-1,2,4-oxadiazol-5-yl)-1-(2-oxo-3-(4-phenoxyphenoxy)propyl)-1H-indole-5-carboxylic acid (3); and 3-(3-methyl-1,2,4-oxadiazol-5-yl)-1-(3-(4-octylphenoxy)-2-oxopropyl)-1H-indole-5-carboxylic acid (4), for labelling in carboxyl position with carbon-11 (t1/2 =20.4 min) to provide candidate PET radioligands for imaging brain cPLA2α. Compounds [11 C]1-4 were obtained for intravenous injection in adequate overall yields (1.1-5.5 %) from cyclotron-produced [11 C]carbon dioxide and with moderate molar activities (70-141 GBq µmol-1 ) through the use of Pd0 -mediated [11 C]carbon monoxide insertion on iodo precursors. Measured logD7.4 values were within a narrow moderate range (1.9-2.4). After intravenous injection of [11 C]1-4 in mice, radioactivity uptakes in brain peaked at low values (≤0.8 SUV) and decreased by about 90 % over 15 min. Pretreatments of the mice with high doses of the corresponding non-radioactive ligands did not alter brain time-activity curves. Brain uptakes of radioactivity after administration of [11 C]1 to wild-type and P-gp/BCRP dual knock-out mice were similar (peak 0.4 vs. 0.5 SUV), indicating that [11 C]1 and others in this structural class, are not substrates for efflux transporters.

Trivalent Gd-DOTA reagents for modification of proteins.

The development of novel protein-targeted MRI contrast agents crucially depends on the ability to derivatise suitable targeting moieties with a high payload of relaxation enhancer (e.g., gadolinium(iii) complexes such as Gd-DOTA), without losing affinity for the target proteins. Here, we report robust synthetic procedures for the preparation of trivalent Gd-DOTA reagents with various chemical handles for site-specific modification of biomolecules. The reagents were shown to successfully label proteins through isothiocyanate ligation or through site-specific thiol-maleimide ligation and strain-promoted azide-alkyne cycloaddition.

Comparison of peripheral forearm DXA and clinical risk factor screening using FRAX® to assess the risk of HIV-associated low bone mass: a cross-sectional study.

UNLABELLED: There is growing awareness that HIV infection is associated with low bone mass and fracture. DXA is a relatively scarce resource. Therefore, we evaluated two tools: peripheral DXA (pDXA) at the forearm and Fracture Risk Assessment Tool (FRAX®) to see which performed best at identifying men who should undergo DXA. In this setting, neither pDXA nor FRAX® showed good sensitivity and specificity for DXA. PURPOSE: Infection with human immunodeficiency virus (HIV) is associated with an increased risk of low bone mineral density (BMD) and fractures. European guidance advocates screening using the FRAX® tool at diagnosis, on initiation of antiretroviral therapy and biannually thereafter in order to decide the need for DXA scanning. This cross-sectional study evaluates the performance of FRAX® and compares its sensitivity and specificity with that of another screening tool, peripheral forearm DXA (pDXA). METHODS: HIV-infected men with varying exposure to antiretroviral therapies were recruited. FRAX® scores were calculated for all participants and everybody underwent pDXA scanning. Femoral neck and lumbar spine BMD was acquired on a Hologic QDR machine by an assessor blinded to the results of the FRAX® and pDXA. RESULTS: One hundred and sixty-eight men (median age 45 years) were recruited with a median duration since HIV diagnosis of 74 months. In total, 21 % of subjects had either osteoporosis (aged ≥50 years) or BMD lower than expected for age (aged <50 years), according to axial DXA. Using a pDXA screening threshold of T ≤ -0.9, sensitivity was high (91 %) in defining those with the worst BMD on axial DXA but with poorer specificity (33 %). Alternately, using a threshold of T ≤ -2.7 reduced sensitivity (34 %) with an increase in specificity (91 %). FRAX® with HIV included as a secondary risk factor had poor sensitivity (31 %) and specificity (74 %) for detecting those with the poorest BMD on axial DXA. CONCLUSION: In this setting, neither pDXA scanning nor FRAX® was sensitive and specific for low bone mass on DXA and neither was performance much improved by using both screening tools. Prospective studies with fracture as an outcome are required in HIV.

Prevalence of and risk factors for osteoporosis and fracture among a male HIV-infected population in the UK.

Rates of osteoporosis and fracture may be increased in HIV but there are few UK data. Our aim was to examine the prevalence of and risk factors for osteoporosis and fractures among a homogeneous cohort of well-characterized HIV-infected men. In total, 168 men were recruited, median age 45 years, 37 combination antiretroviral therapy (cART) naïve, 46 with <3 years cART exposure and 85 cART-exposed longer term (median >10 years). All participants provided information on bone health and underwent DEXA scanning. Osteopenia was found in 58% of subjects and osteoporosis in 12%; 14% reported fractures since HIV diagnosis. Number of fractures since HIV diagnosis was significantly increased among those with osteoporosis (OR 3.5, 95% CI 1.2-10.4, p = 0.018). Duration of infection greater than 13 years was significantly associated with osteoporosis. Duration of cART was associated in univariate but not multivariate analyses. Strategies to prevent osteoporosis and fractures in HIV will require attention to viral and lifestyle factors and not just cART.

Effects of hydroxychloroquine on immune activation and disease progression among HIV-infected patients not receiving antiretroviral therapy: a randomized controlled trial.

CONTEXT: Therapies to decrease immune activation might be of benefit in slowing HIV disease progression. OBJECTIVE: To determine whether hydroxychloroquine decreases immune activation and slows CD4 cell decline. DESIGN, SETTING, AND PATIENTS: Randomized, double-blind, placebo-controlled trial performed at 10 HIV outpatient clinics in the United Kingdom between June 2008 and February 2011. The 83 patients enrolled had asymptomatic HIV infection, were not taking antiretroviral therapy, and had CD4 cell counts greater than 400 cells/µL. INTERVENTION: Hydroxychloroquine, 400 mg, or matching placebo once daily for 48 weeks. MAIN OUTCOME MEASURES: The primary outcome measure was change in the proportion of activated CD8 cells (measured by the expression of CD38 and HLA-DR surface markers), with CD4 cell count and HIV viral load as secondary outcomes. Analysis was by intention to treat using mixed linear models. RESULTS: There was no significant difference in CD8 cell activation between the 2 groups (-4.8% and -4.2% in the hydroxychloroquine and placebo groups, respectively, at week 48; difference, -0.6%; 95% CI, -4.8% to 3.6%; P = .80). Decline in CD4 cell count was greater in the hydroxychloroquine than placebo group (-85 cells/µL vs -23 cells/µL at week 48; difference, -62 cells/µL; 95% CI, -115 to -8; P = .03). Viral load increased in the hydroxychloroquine group compared with placebo (0.61 log10 copies/mL vs 0.23 log10 copies/mL at week 48; difference, 0.38 log10 copies/mL; 95% CI, 0.13 to 0.63; P = .003). Antiretroviral therapy was started in 9 patients in the hydroxychloroquine group and 1 in the placebo group. Trial medication was well tolerated, but more patients reported influenza-like illness in the hydroxychloroquine group compared with the placebo group (29% vs 10%; P = .03). CONCLUSION: Among HIV-infected patients not taking antiretroviral therapy, the use of hydroxychloroquine compared with placebo did not reduce CD8 cell activation but did result in a greater decline in CD4 cell count and increased viral replication. TRIAL REGISTRATION: isrctn.org Identifier: ISRCTN30019040.

Angiotensin converting enzyme (ACE) and ACE2 bind integrins and ACE2 regulates integrin signalling.

The angiotensin converting enzymes (ACEs) are the key catalytic components of the renin-angiotensin system, mediating precise regulation of blood pressure by counterbalancing the effects of each other. Inhibition of ACE has been shown to improve pathology in cardiovascular disease, whilst ACE2 is cardioprotective in the failing heart. However, the mechanisms by which ACE2 mediates its cardioprotective functions have yet to be fully elucidated. Here we demonstrate that both ACE and ACE2 bind integrin subunits, in an RGD-independent manner, and that they can act as cell adhesion substrates. We show that cellular expression of ACE2 enhanced cell adhesion. Furthermore, we present evidence that soluble ACE2 (sACE2) is capable of suppressing integrin signalling mediated by FAK. In addition, sACE2 increases the expression of Akt, thereby lowering the proportion of the signalling molecule phosphorylated Akt. These results suggest that ACE2 plays a role in cell-cell interactions, possibly acting to fine-tune integrin signalling. Hence the expression and cleavage of ACE2 at the plasma membrane may influence cell-extracellular matrix interactions and the signalling that mediates cell survival and proliferation. As such, ectodomain shedding of ACE2 may play a role in the process of pathological cardiac remodelling.

Trimetrexate and folinic acid: a valuable salvage option for Pneumocystis jirovecii pneumonia.

The best management strategy for HIV patients who fail to respond to first-line therapy for Pneumocystis jirovecii pneumonia is currently unclear. We identified all patients who were treated with trimetrexate and folinic acid who failed 7 or more days of cotrimoxazole, clindamycin-primaquine or dapsone-trimethoprim between 1996 and 2006. Trimetrexate was tolerated in 100% of cases with no treatment termination secondary to adverse drug reactions. Despite severe disease, 71% of patients were alive after 12 weeks.

Making sense of syphilis: beliefs, behaviours and disclosure among gay men recently diagnosed with infectious syphilis and the implications for prevention.

BACKGROUND: The resurgence of syphilis in men who have sex with men (MSM) has proved remarkably resilient in the face of innovative control and prevention interventions. Understanding the determinants of the current outbreaks has been restricted by the available data. Qualitative work is needed to understand individual and community experiences of syphilis and to help guide new prevention and control efforts. METHODS: An exploratory study using semi-structured interviews with a convenience sample of MSM (n = 15), recently diagnosed with infectious syphilis, attending sexual health and HIV-outpatient services in Brighton, England. RESULTS: Analysis focussed on men's beliefs about syphilis, their experience of testing and being given a syphilis diagnosis, mediators of 'risky' sexual behaviour and disclosure to social and sexual contacts. Two beliefs--'syphilis is rare' and 'syphilis is dirty'--dominated respondents' accounts. These beliefs coloured every aspect of respondents' clinical and social experience of syphilis, and impeded disclosure and partner notification. They also contributed to misconceptions about behaviours with increased syphilis transmission risk, the mechanics of disease acquisition, health-seeking behaviours and risk-reduction strategies. CONCLUSIONS: The apparent failure of syphilis control measures so far may be due to our limited understanding of MSM's views and experience of STIs other than HIV Syphilis prevention needs to tackle MSM's widely held beliefs about sexual communication, risk behaviour and other STIs. The most useful health education interventions are likely to be those that build on MSM's significant knowledge base and address both the current syphilis crisis and wider sexual health promotion goals.

The re-emergence of syphilis in the United Kingdom: the new epidemic phases.

OBJECTIVE: The objective of this study was to characterize the resurgence of infectious syphilis in the United Kingdom between 1997 and 2003. STUDY: The authors conducted a retrospective analysis of routine surveillance data from genitourinary medicine clinics and data collected through enhanced surveillance. RESULTS: Between 1997 and 2002, diagnoses of primary, secondary, and early latent syphilis made at genitourinary medicine clinics increased by 213% in heterosexual males, 1412% in men who have sex with men (MSM), and 22% in females. These increases have been driven by a series of outbreaks, the largest of which were seen in Manchester (528) and London (1222) up to the end of October 2003. All the outbreaks have been geographically localized and the majority of cases occurred in MSM. A high percentage of concurrent HIV infection was reported, and oral sex was often reported as a route of transmission. CONCLUSIONS: Syphilis has re-emerged in response to behavior change, probably driven by changes in the HIV epidemic. The future course of the epidemic is difficult to predict and control remains elusive.