Impaired flow-induced dilation in mesenteric resistance arteries from receptor protein tyrosine phosphatase-mu-deficient mice

The transmembrane receptor-like protein tyrosine phosphatase-mu (RPTPmu) is thought to play an important role in cell-cell adhesion-mediated processes. We recently showed that RPTPmu is predominantly expressed in the endothelium of arteries and not in veins. Its involvement in the regulation of endothelial adherens junctions and its specific arterial expression suggest that RPTPmu plays a role in controlling arterial endothelial cell function and vascular tone. To test this hypothesis, we analyzed myogenic responsiveness, flow-induced dilation, and functional integrity of mesenteric resistance arteries from RPTPmu-deficient (RPTPmu(-/-)) mice and from wild-type littermates. Here, we show that cannulated mesenteric arteries from RPTPmu(-/-) mice display significantly decreased flow-induced dilation. In contrast, mechanical properties, myogenic responsiveness, responsiveness to the vasoconstrictors phenylephrine or U-46619, and responsiveness to the endothelium-dependent vasodilators methacholine or bradykinin were similar in both groups. Our results imply that RPTPmu is involved in the mechanotransduction or accessory signaling pathways that control shear stress responses in mesenteric resistance arteries.     

Madurella mycetomatis Is Highly Susceptible to Ravuconazole

The current treatment of eumycetoma utilizing ketoconazole is unsatisfactory because of high recurrence rates, which often leads to complications and unnecessary amputations, and its comparatively high cost in endemic areas. Hence, an effective and affordable drug is required to improve therapeutic outcome. E1224 is a potent orally available, broad-spectrum triazole currently being developed for the treatment of Chagas disease. E1224 is a prodrug that is rapidly converted to ravuconazole. Plasma levels of E1224 are low and transient, and its therapeutically active moiety, ravuconazole is therapeutically active. In the present study, the in vitro activity of ravuconazole against Madurella mycetomatis, the most common etiologic agent of eumycetoma, was evaluated and compared to that of ketoconazole and itraconazole. Ravuconazole showed excellent activity with MICs ranging between ≤0.002 and 0.031 µg/ml, which were significantly lower than the MICs reported for ketoconazole and itraconazole. On the basis of our findings, E1224 with its resultant active moiety, ravuconazole, could be an effective and affordable therapeutic option for the treatment of eumycetoma.     

The Mycetoma Knowledge Gap: Identification of Research Priorities

Mycetoma is a tropical disease which is caused by a taxonomically diverse range of actinomycetes (actinomycetoma) and fungi (eumycetoma). The disease was only recently listed by the World Health Organization (WHO) as a neglected tropical disease (NTD). This recognition is the direct result of a meeting held in Geneva on February 1, 2013, in which experts on the disease from around the world met to identify the key research priorities needed to combat mycetoma. The areas that need to be addressed are highlighted here. The initial priority is to establish the incidence and prevalence of the disease in regions where mycetoma is endemic, prior to determining the primary reservoirs of the predominant causal agents and their mode of transmission to susceptible individuals in order to establish novel interventions that will reduce the impact of the disease on individuals, families, and communities. Critically, economical, reliable, and effective methods are required to achieve early diagnosis of infections and consequential improved therapeutic outcomes. Molecular techniques and serological assays were considered the most promising in the development of novel diagnostic tools to be used in endemic settings. Improved strategies for treating eumycetoma and actinomycetoma are also considered.     

Merits and Pitfalls of Currently Used Diagnostic Tools in Mycetoma

Treatment of mycetoma depends on the causative organism and since many organisms, both actinomycetes (actinomycetoma) and fungi (eumycetoma), are capable of producing mycetoma, an accurate diagnosis is crucial. Currently, multiple diagnostic tools are used to determine the extent of infections and to identify the causative agents of mycetoma. These include various imaging, cytological, histopathological, serological, and culture techniques; phenotypic characterisation; and molecular diagnostics. In this review, we summarize these techniques and identify their merits and pitfalls in the identification of the causative agents of mycetoma and the extent of the disease. We also emphasize the fact that there is no ideal diagnostic tool available to identify the causative agents and that future research should focus on the development of new and reliable diagnostic tools.     

The T-cell antigen receptor: a logical response to an unknown ligand

The immune system can be roughly divided into innate and adaptive compartments. The adaptive compartment includes the B and T lymphocytes, whose antigen receptors are generated by recombination of gene segments. The consequence is that the creation of self-reactive lymphocytes is unavoidable. For the host to remain viable, the immune system has evolved a strategy for removing autoimmune lymphocytes during development. This review discusses how T lymphocytes are generated, how they recognize antigens, and how their antigen receptor directs the removal of self-reactive T cells.     

Knowledge,Attitudes, and Acceptability of Pre-Exposure Prophylaxis among Individuals Living with HIV in an Urban HIV Clinic

Introduction

Pre-exposure prophylaxis (PrEP) is an effective tool to reduce HIV transmission. The primary objective of this study was to assess awareness of PrEP by individuals living with HIV (HIV+) and acceptance of its use for their HIV negative (HIV-) partners.

Methods

A cross sectional survey was conducted among individuals living with HIV who received care at an urban HIV clinic between January 2013 and June 2013. The survey examined knowledge, attitudes, and acceptability of PrEP, and perception of transmission risk of HIV. Chi-Square test and Fisher''s Exact test were used to compare proportions.

Results

Among 206 subjects living with HIV, 15.3% (32) had heard of PrEP. Men who have sex with men (MSM) were more likely to be aware of PrEP than all others (p = 0.003). Once educated about PrEP those who believed PrEP would reduce their partner’s risk for HIV were more likely to recommend PrEP to their partner (p<0.001). 92% of all respondents said they would be “extremely likely/likely” to discuss PrEP use with their provider. Of 159 subjects whose main partner was HIV-, MSM (p = 0.007), male participants (p = 0.044), and those who were consistently taking meds (p = 0.049) were more likely to be aware of PrEP. Those who perceived they were at risk of transmitting HIV (p<0.001) and those who were consistently taking meds (0.049) were more likely to agree that PrEP could reduce the risk of HIV to their partners.

Conclusion

This study illustrates a low awareness of PrEP but once educated the willingness of a cohort of individuals living with HIV to recommend PrEP to their partners. Our findings demonstrate the importance of providers informing their patients living with HIV about PrEP, as these persons are an underutilized link to support the uptake of PrEP by their HIV- partners.     

Monitoring Bacterial Burden,Inflammation and Bone Damage Longitudinally Using Optical and μCT Imaging in an Orthopaedic Implant Infection in Mice

Background

Recent advances in non-invasive optical, radiographic and μCT imaging provide an opportunity to monitor biological processes longitudinally in an anatomical context. One particularly relevant application for combining these modalities is to study orthopaedic implant infections. These infections are characterized by the formation of persistent bacterial biofilms on the implanted materials, causing inflammation, periprosthetic osteolysis, osteomyelitis, and bone damage, resulting in implant loosening and failure.

Methodology/Principal Findings

An orthopaedic implant infection model was used in which a titanium Kirshner-wire was surgically placed in femurs of LysEGFP mice, which possess EGFP-fluorescent neutrophils, and a bioluminescent S. aureus strain (Xen29; 1×10³ CFUs) was inoculated in the knee joint before closure. In vivo bioluminescent, fluorescent, X-ray and μCT imaging were performed on various postoperative days. The bacterial bioluminescent signals of the S. aureus-infected mice peaked on day 19, before decreasing to a basal level of light, which remained measurable for the entire 48 day experiment. Neutrophil EGFP-fluorescent signals of the S. aureus-infected mice were statistically greater than uninfected mice on days 2 and 5, but afterwards the signals for both groups approached background levels of detection. To visualize the three-dimensional location of the bacterial infection and neutrophil infiltration, a diffuse optical tomography reconstruction algorithm was used to co-register the bioluminescent and fluorescent signals with μCT images. To quantify the anatomical bone changes on the μCT images, the outer bone volume of the distal femurs were measured using a semi-automated contour based segmentation process. The outer bone volume increased through day 48, indicating that bone damage continued during the implant infection.

Conclusions/Significance

Bioluminescent and fluorescent optical imaging was combined with X-ray and μCT imaging to provide noninvasive and longitudinal measurements of the dynamic changes in bacterial burden, neutrophil recruitment and bone damage in a mouse orthopaedic implant infection model.     

Interaction between growth hormone and insulin in the regulation of lipoprotein metabolism in the rat

The importance of insulin for the in vivo effects of growth hormone (GH) on lipid and lipoprotein metabolism was investigated by examining the effects of GH treatment of hypophysectomized (Hx) female rats with and without concomitant insulin treatment. Hypophysectomy-induced changes of HDL, apolipoprotein (apo)E, LDL, and apoB levels were normalized by GH treatment but not affected by insulin treatment. The hepatic triglyceride secretion rate was lower in Hx rats than in normal rats and increased by GH treatment. This effect of GH was blunted by insulin treatment. The triglyceride content in the liver changed in parallel with the changes in triglyceride secretion rate, indicating that the effect of the hormones on triglyceride secretion was dependent on changed availability of triglycerides for VLDL assembly. GH and insulin independently increased editing of apoB mRNA, but the effects were not additive. The expression of fatty-acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD-1), and sterol regulatory element-binding protein-1c (SREBP-1c) was increased by GH treatment. Insulin and GH had no additive effects on these genes; instead, insulin blunted the effect of GH on SREBP-1c mRNA. In contrast to the liver, adipose tissue expression of SREBP-1c, FAS, or SCD-1 mRNA was not influenced by GH. In conclusion, the increased hepatic expression of lipogenic enzymes after GH treatment may be explained by increased expression of SREBP-1c. Insulin does not mediate the effects of GH but inhibits the stimulatory effect of GH on hepatic SREBP-1c expression and triglyceride secretion rate.     

The tRNA aminoacylation co-factor Arc1p is excluded from the nucleus by an Xpo1p-dependent mechanism

Arc1p, a yeast tRNA-binding protein, forms a complex with the aminoacyl-tRNA synthetases, methionyl tRNA synthetase (MetRS) and glutamyl tRNA synthetase (GluRS). Although this complex localizes normally in the cytoplasm, in the absence of Arc1p the two free synthetases are also found inside the nucleus. In this work, in order to localize free Arc1 we abolished complex assembly by deleting the appended domains from both MetRS and GluRS. Surprisingly, free Arc1p remained cytoplasmic even when fitted with a strong nuclear localization signal (NLS). However, NLS-Arc1p accumulated in the nucleus when Xpo1/Crm1, the export receptor for NES-containing cargo proteins, was mutated. Thus, the cytoplasmic location of Arc1p is maintained by Xpo1p-dependent nuclear export and Arc1p could act as an adapter in the nucleocytoplasmic trafficking of tRNA and/or the tRNA-aminoacylation machinery.