A Mycobacterium ulcerans toxin, mycolactone, causes apoptosis in guinea pig ulcers and tissue culture cells

Mycobacterium ulcerans is the causative agent of Buruli ulcer, a tropical ulcerative skin disease. One of the most intriguing aspects of this disease is the presence of extensive tissue damage in the absence of an acute inflammatory response. We recently purified and characterized a macrolide toxin, mycolactone, from M. ulcerans. Injection of this molecule into guinea pig skin reproduced cell death and lack of acute inflammatory response similar to that seen following the injection of viable bacteria. We also showed that mycolactone causes a cytopathic effect on mouse fibroblast L929 cells that is characterized by cytoskeletal rearrangements and growth arrest within 48 h. However, these results could not account for the extensive cell death which occurs in Buruli ulcer. The results presented here demonstrate that L929 and J774 mouse macrophage cells die via apoptosis after 3 to 5 days of exposure to mycolactone. Treatment of cells with a pan-caspase inhibitor can inhibit mycolactone-induced apoptosis. We demonstrate that injection of mycolactone into guinea pig skin results in cell death via apoptosis and that the extent of apoptosis increases as the lesion progresses. These results may help to explain why tissue damage in Buruli ulcer is not accompanied by an acute inflammatory response.     

Secretion of vascular endothelial growth factor/vascular permeability factor from human luteinized granulosa cells is human chorionic gonadotrophin dependent

Vascularization is a prominent event during corpus luteum formation, providing low density lipoproteins for steroid biosynthesis and enabling transport of secreted steroids. The process of vascularization is controlled by specific regulators. Vascular endothelial growth factor (VEGF), otherwise named vascular permeability factor (VPF), induces endothelial cell proliferation as well as angiogenesis in vivo and increases capillary permeability. Here we report the expression of VEGF/VPF mRNA by cultured human luteinized granulosa cells (GC) for at least 10 days. Without HCG VEGF/VPF expression declined after day 4 and by day 10 was reduced to approximately 30% of the value at day 4. However, after culture in the presence of 1 U/ml human chorionic gonadotrophin (HCG), expression of VEGF/VPF mRNA by GC was four times greater than control experiments by day 10, and increased 100% from day 4 to day 10. Simultaneously, HCG supplementation increased VEGF/VPF secretion by GC. Medium VEGF/VPF on day 3 was 13 pM without and 11 pM with HCG. Medium VEGF/VPF on day 10 was 6 pM without HCG and 29 pM with HCG. These results suggest that vascularization of the corpus luteum is induced by HCG-mediated effects of VEGF/VPF.      

Differentiation of Mycobacterium ulcerans, M. marinum, and M. haemophilum: Mapping of Their Relationships to M. tuberculosis by Fatty Acid Profile Analysis, DNA-DNA Hybridization, and 16S rRNA Gene Sequence Analysis

Although Mycobacterium ulcerans, M. marinum, and M. haemophilum are closely related, their exact taxonomic placements have not been determined. We performed gas chromatography of fatty acids and alcohols, as well as DNA-DNA hybridization and 16S rRNA gene sequence analysis, to clarify their relationships to each other and to M. tuberculosis. M. ulcerans and M. marinum were most closely related to one another, and each displayed very strong genetic affinities to M. tuberculosis; they are actually the two mycobacterial species outside the M. tuberculosis complex most closely related to M. tuberculosis. M. haemophilum was more distinct from M. ulcerans and M. marinum, and it appeared to be as related to these two species as to M. tuberculosis. These results are important with regard to the development of diagnostic and epidemiological tools such as species-specific DNA probes and PCR assays for M. ulcerans, M. marinum, and M. haemophilum. In addition, the finding that M. ulcerans and M. marinum are more closely related to M. tuberculosis than are other pathogenic mycobacterial species suggests that they may be evaluated as useful models for studying the pathogenesis of M. tuberculosis. M. marinum may be particularly useful in this regard since strains of this species grow much more rapidly than M. tuberculosis and yet can cause systemic disease in immunocompromised hosts.     

Biological resurfacing of the knee: a review of surgical management

Lesions of the articular surfaces of the knee have been managed by various techniques over the last 50 years. Surgical management has involved: excising the damaged area, refashioning the underlying bone to produce a fibrous response, and introducing allograft, autograft and synthetic materials to encourage a repair matrix. The techniques and their pitfalls are reviewed and discussed, and suggestions made as to the direction of future studies for the repair of osteochondral lesions in the painful knee.     

LC determination of the diastereomers of 1-(beta-D-glucopyranosyl)phenobarbital in human urine

The "product enantioselectivity" associated with the urinary excretion of the phenobarbital N-glucoside conjugates has not been determined previously. A liquid chromatography method using gradient elution was developed for quantifying both phenobarbital N-glucoside conjugates, phenobarbital, and p-hydroxyphenobarbital. Following a single oral dose of phenobarbital to male Caucasian and Oriental subjects, both phenobarbital N-glucoside conjugates were observed in the urine. In seven subjects, 3.3-10.6% of the phenobarbital dose was detected as a single phenobarbital N-glucoside (S configuration at the C-5 position of the barbiturate ring). The other phenobarbital N-glucoside diastereomer accounted for less than 1.5% of the phenobarbital dose. The urinary excretion of the major phenobarbital N-glucoside diastereomer paralleled the urinary excretion of phenobarbital and was comparable in both Caucasian and Oriental subjects. These results indicate a pronounced selectivity for the formation and/or urinary excretion of the phenobarbital N-glucosides.     

RENAL TRANSPLANTATION – AN EARLY EXPERIENCE

Renal transplant (RT) is now a therapy of choice for end stage renal disease (ESRD). The Nephrology Unit, Asvini started functioning in Dec 90 and to date 1298 sittings of hemodialysis have been given to 45 patients. Of these, 35 were in ESRD and 11 patients underwent renal transplantation at this hospital during the period Jan 91 – Dec 93. One patient expired after 18 months of transplantation due to infection. Early experience in screening patients for RT, use of immunosuppression, management of rejection episodes and protocol are presented with special emphasis on its relevance to the Armed Forces.KEY WORDS: Transplantation, Renal Failure, Immunosuppression, Rejection