Radiating Collapse with Vanishing Weyl stresses

In a recent approach in modelling a radiating relativistic star undergoing gravitational collapse the role of the Weyl stresses was emphasised. It is possible to generate a model which is physically reasonable by approximately solving the junction conditions at the boundary of the star. In this paper we demonstrate that it is possible to solve the Einstein field equations and the junction conditions exactly. This exact solution contains the Friedmann dust solution as a limiting case. We briefly consider the radiative transfer within the framework of extended irreversible thermodynamics and show that relaxational effects significantly alter the temperature profiles.Comment: 10 pages, submitted to IJMP-

Inflation driven by causal heat flux

We find a simple inflationary solution in an inhomogeneous spacetime with heat flux. The heat flux obeys a causal transport equation, and counteracts the inflationary decrease of energy density. At late times, the heat flux tends to zero and the fluid approaches the equation of state $p=-\rho$.Comment: Latex 5 pages; to appear Gen. Rel. Gra

Relaxational effects in radiating stellar collapse

Relaxational effects in stellar heat transport can in many cases be significant. Relativistic Fourier-Eckart theory is inherently quasi-stationary, and cannot incorporate these effects. The effects are naturally accounted for in causal relativistic thermodynamics, which provides an improved approximation to kinetic theory. Recent results, based on perturbations of a static star, show that relaxation effects can produce a significant increase in the central temperature and temperature gradient for a given luminosity. We use a simple stellar model that allows for non-perturbative deviations from staticity, and confirms qualitatively the predictions of the perturbative models

Radiating spherical collapse with heat flow

We present here a simple model of radiative gravitational collapse with radial heat flux which describes qualitatively the stages close to the formation of a superdense cold star. Starting with a static general solution for a cold star, the model can generate solutions for the earlier evolutionary stages. The temporal evolution of the model is specified by solving the junction conditions appropriate for radiating gravitational collapse.Comment: 13 pages, including 3 figures, submitted to IJMP-

IL-2-Mediated In Vivo Expansion of Regulatory T Cells Combined with CD154-CD40 Co-Stimulation Blockade but Not CTLA-4 Ig Prolongs Allograft Survival in Naive and Sensitized Mice.

In recent years, regulatory T cells (Treg)-based immunotherapy has emerged as a promising strategy to promote operational tolerance after solid organ transplantation (SOT). However, a main hurdle for the therapeutic use of Treg in transplantation is their low frequency, particularly in non-lymphopenic hosts. We aimed to expand Treg directly in vivo and determine their efficacy in promoting donor-specific tolerance, using a stringent experimental model. Administration of the IL-2/JES6-1 immune complex at the time of transplantation resulted in significant expansion of donor-specific Treg, which suppressed alloreactive T cells. IL-2-mediated Treg expansion in combination with short-term CD154-CD40 co-stimulation blockade, but not CTLA-4 Ig or rapamycin, led to tolerance to MHC-mismatched skin grafts in non-lymphopenic mice, mainly by hindering alloreactive CD8(+) effector T cells and the production of alloantibodies. Importantly, this treatment also allowed prolonged survival of allografts in the presence of either donor-specific or cross-reactive memory cells. However, late rejection occurred in sensitized hosts, partly mediated by activated B cells. Overall, these data illustrate the potential but also some important limitations of Treg-based therapy in clinical SOT as well as the importance of concomitant immunomodulatory strategies in particular in sensitized hosts

Elevated Risk of Suicidal Ideation in HIV-Positive Persons

Globally, suicide and HIV/AIDS remain two of the greatest healthcare issues, particularly in low-and middle-income countries. Several studies have observed a relationship between suicidal behaviour and HIV/AIDS. Materials and Methods. The main objective of this research was to determine the prevalence of elevated risk of suicidal ideation in HIV-positive persons immediately following voluntary HIV counselling and testing (VCT). The study sample consisted of adult volunteers attending the VCT clinic at a university-affiliated, general state hospital. Participants completed a sociodemographic questionnaire, Beck's Hopeless Scale, and Beck's Depression Inventory. Results. A significantly elevated risk of suicidal ideation was found in 83.1% of the patients who tested seropositive. Despite a wide age range in the cohort studied, the majority of patients with suicidal ideation were males in the younger age group (age < 30 years), consistent with the age-related spread of the disease and an increase in suicidal behaviour in younger people. Relevant associated variables are discussed. Conclusion. The results serve as important markers that could alert healthcare professionals to underlying suicide risks in HIV-positive patients. It is recommended that screening for elevated risk of suicidal ideation and prevention of suicidal behaviour should form a routine aspect of comprehensive patient care at VCT clinics

Antifungal activity of epithelial secretions from selected frog species of South Africa

Resistance to antibiotics has been acknowledged as a major global public health problem. The use of antimicrobial peptides to provide alternatives to combat multi-drug antibiotic resistance is beginning to attract increasing attention. The high diversity of amphibian skin peptides renders anurans an important potential source for the discovery of novel pharmacophores. This study aimed to investigate the antifungal activity of skin secretions from selected frogs (Amietia fuscigula, Strongylopus grayi and Xenopus laevis) and one toad (Amietophrynus pantherinus) of the south Western Cape Province of South Africa. Initially, different extraction techniques for the collection of skin secretions were tested and optimized, thereafter the extracts were tested against three fungal species of medical and agricultural importance that is, Candida albicans, Fusarium verticillioides and Aspergillus flavus. Chemical stimulation gave the best yield by mass, and secretions from A. fuscigula showed the best activity with an MIC of 40 μg / ml against C. albicans and 200 μg / ml against A. flavus. In general, C. albicans and A. flavus were the most sensitive while F. verticillioides was the most resistant. From this study it appears that bioprospecting of South African frog species has the potential to yield potential therapeutic lead agents.Key words: Antifungal, African anurans, antimicrobial peptides (AMP), Candida albicans, Aspergillus flavus, bioprospecting, minimum inhibitory concentrations (MIC)