Methylthiomethyl,a new carboxyl protecting group in peptide synthesis

N^α-protected amino acid methylthiomethyl esters (MTM) were obtained in good yields under mild conditions using the «Bu^tBr/Me₂SO» reagent. Selective removal of the N-protecting group was achieved in HCl/anhydrous ethyl ether and the MTM ester hydrochlorides were successfully used in the synthesis of dipeptides.     

Has echography modified the occurrence of kidney carcinoma? Considerations on 316 cases

An analysis of 316 renal carcinomas over an 11-year period has shown an increase in the incidence of tumors per year, together with a progressive decrease in the size of the lesions at the time of diagnosis. This effect occurred especially after the introduction of renal ultrasonography in diagnostic practice. The tumor size is an important prognostic factor, because the 5-year survival rate was 80% for tumors less than 5 cm and 30% for tumors greater than 10 cm. Ultrasonography might thus represent a screening method for renal carcinoma in patients over 50 years of age, if it were possible to define risk groups.     

Antileishmanial activity of a linalool-rich essential oil from Croton cajucara

The in vitro leishmanicidal effects of a linalool-rich essential oil from the leaves of Croton cajucara against Leishmania amazonensis were investigated. Morphological changes in L. amazonensis promastigotes treated with 15 ng of essential oil per ml were observed by transmission electron microscopy; leishmanial nuclear and kinetoplast chromatin destruction, followed by cell lysis, was observed within 1 h. Pretreatment of mouse peritoneal macrophages with 15 ng of essential oil per ml reduced by 50% the interaction between these macrophages and L. amazonensis, with a concomitant increase by 220% in the level of nitric oxide production by the infected macrophages. Treatment of preinfected macrophages with 15 ng of essential oil per ml reduced by 50% the interaction between these cells and the parasites, which led to a 60% increase in the amount of nitric oxide produced by the preinfected macrophages. These results provide new perspectives on the development of drugs with activities against Leishmania, as linalool-rich essential oil is a strikingly potent leishmanicidal plant extract (50% lethal doses, 8.3 ng/ml for promastigotes and 8.7 ng/ml for amastigotes) which inhibited the growth of L. amazonensis promastigotes at very low concentrations (MIC, 85.0 pg/ml) and which presented no cytotoxic effects against mammalian cells.     

Radiologic surveillance of uremic osteodystrophy after parathyroidectomy

Partial parathyroidectomy (PTX) was carried out 20 times in 15 dialitic patients with chronic renal failure. The operation was suggested by marked radiological abnormalities due to severe secondary hyperparathyroidism, that developed despite aggressive medical and dietetic management. The skeletal x-ray examination showed significant improvement following PTX, that was clearly visible already one month postoperatively at the level of the second and third phalanges of the hands. The improvement of the skeletal osteodystrophic patterns was always associated to a fall of parathyroid hormone and plasma alkaline phosphatase levels. The radiological examination of the hands may represent a usefull and simple method in the follow-up of patients after surgery to assess the efficacy of PTX.     

Molecular typing and antimicrobial susceptibility of vancomycin-resistant Enterococcus faecium in Brazil.

OBJECTIVES: To characterize vancomycin-resistant enterococci (VRE) isolates and to evaluate the mode of dissemination of this pathogen in Brazil. DESIGN: We collected 22 vancomycin-resistant Enterococcus faecium isolates from 6 medical centers in Sao Paulo, Brazil, and 1 isolate from a medical center in Curitiba, Brazil. PARTICIPANTS: All Brazilian hospitals that had identified vancomycin-resistant E. faecium up to the beginning of this study (late 1999) contributed isolates to the study. METHODS: The isolates were susceptibility tested using the broth microdilution method and the E-test. The presence of vancomycin resistance genes (vanA, vanB, vanC1, vanC2-3, and vanD) was evaluated by polymerase chain reaction; molecular typing was performed by pulsed-field gel electrophoresis (PFGE). RESULTS: The vanA gene was demonstrated in all vancomycin-resistant E. faecium, except for 1 isolate. None of the vancomycin resistance genes cited above was detected in the isolate from Curitiba, which was the first vancomycin-resistant E. faecium described in Brazil. All isolates were resistant to ampicillin and teicoplanin. The main clone remains susceptible to doxycycline and chloramphenicol, but intermediate to quinupristin-dalfopristin. PFGE analysis demonstrated 7 major PFGE patterns. A unique PFGE pattern with 4 subtypes was detected in 17 isolates from 4 different hospitals. CONCLUSION: The results of our study indicate the occurrence of intra- and interhospital dissemination of VRE in Sao Paulo, Brazil.     

Sirolimus-eluting stents associated with paradoxic coronary vasoconstriction

OBJECTIVES: The purpose of the present study was to assess coronary vasomotor response to exercise after sirolimus-eluting stent (SES) implantation. BACKGROUND: Sirolimus-eluting stents have been shown to markedly reduce the incidence of angiographic and clinical restenosis. However, long-term effects of sirolimus on endothelial function are unknown. METHODS: Coronary vasomotion was evaluated with biplane quantitative coronary angiography at rest and during supine bicycle exercise in 25 patients with coronary artery disease. Eleven patients were treated with a bare-metal stent (BMS) (control group) and 14 patients underwent SES implantation (sirolimus group) for de novo coronary artery lesions. Both groups were studied 6 +/- 1 month after the intervention. Minimal luminal diameter; stent diameter; and proximal, distal, and reference vessel diameter were determined. RESULTS: The reference vessel showed exercise-induced vasodilation (+13 +/- 4%) in both groups. Vasomotion within the stented vessel segments was abolished. In controls, the adjacent segments proximal and distal to the stent showed exercise-induced vasodilation (+15 +/- 3% and +17 +/- 4%, respectively). In contrast, there was exercise-induced vasoconstriction of the proximal and distal vessel segments adjacent to SESs (-12 +/- 4% and -15 +/- 6%, respectively; p < 0.001 vs. corresponding segments of controls). Sublingual nitroglycerin was associated with maximal vasodilation of the proximal and distal vessel segments in both groups. CONCLUSIONS: Implantation of a BMS does not affect physiologic response to exercise proximal and distal to the stent. However, SESs are associated with exercise-induced paradoxic coronary vasoconstriction of the adjacent vessel segments, although vasodilatory response to nitroglycerin is maintained. These observations suggest (drug-induced) endothelial dysfunction as the underlying mechanism.