Formulary review of the carbapenems: comparison of imipenem/cilastatin and meropenem

The duplicative mutation of an Ala-Val-Arg sequence at positions 208 to 210 in the loop structure of Enterobacter cloacae class C beta-lactamase caused substrate specificity extension to oxyimino beta-lactam antibiotics and this chromosomal mutation provided bacterial cells with high resistance to the beta-lactams (M. Nukaga et al, 1995, J. Biol. Chem. 270, 5729-5735). In order to confirm the universality of this phenomenon among other class C beta-lactamases, the duplicative mutation was applied to a class C beta-lactamase of Citrobacter freundii, which has 74% homology to the E. cloacae beta-lactamase amino acid sequence. The counterpart sequence to the Ala-Val-Arg of the E. cloacae enzyme in C. freundii beta-lactamase was identified to be Pro-Val-His. A Pro-Val-His sequence was inserted just after the native Pro-Val-His sequence at positions 208 to 210 in the C. freundii beta-lactamase. The resulting mutant of C. freundii beta-lactamase obtained a striking characteristic that we expected, showing substrate specificity extension to oxyimino beta-lactams. Nearly the same result was obtained with the insertion of an Ala-Val-Arg sequence after the native Pro-Val-His sequence. These results indicate that structural modification of this locus commonly induces modification of the substrate specificity to unfavorable substrates for many chromosomal class C beta-lactamases produced by gram-negative bacteria.     

Prodrug esters of the indolocarbazole CEP-751 (KT-6587)

Prodrug esters of the indolocarbazole CEP-751 (KT-6587) were prepared with the goal of identifying water soluble, stable but cleavable forms for intravenous dosing. A dipeptide proform Lys-beta-Ala (16, CEP-2563/KT-8391) was identified for advancement to clinical trials.     

Investigation of the action patterns of pectinmethylesterase isoforms through kinetic analyses and NMR spectroscopy. Implications In cell wall expansion

Well characterized pectin samples were incubated with cell wall-bound and -solubilized pure isoforms of pectinmethylesterase from mung bean hypocotyls (Vigna radiata). Both enzyme activity and average product structure were determined at intervals along the deesterification pathway at pH 5.6 and 7.6. The latter analyses were performed by 13C NMR spectroscopy, and the degree of esterification was probed by both 13C NMR and potentiometric measurements. A dichotomy was observed in the behavior of the alpha and gamma isoforms when compared with that of the beta isoenzyme. Ideal blockwise deesterification mechanisms reproduced the experimental average structures (methylester distribution) throughout the course of the reaction. In the case of the alpha and gamma isoforms, a single chain mechanism associated with a free carboxyl group at the second nearest neighbor position could be postulated at pH 5.6, whereas some multiple attack character was required to reproduce the data at pH 7.6. Several mechanisms that differed from the preceding ones were compatible with the data for the beta isoform at the two pH values. Both the nature of the polysaccharides produced in these reactions and the role of pectinmethylesterase in the cell wall-stiffening process along the growth gradient are discussed.     

TNK-tissue plasminogen activator compared with front-loaded alteplase in acute myocardial infarction: results of the TIMI 10B trial. Thrombolysis in Myocardial Infarction (TIMI) 10B Investigators

BACKGROUND: Bolus thrombolytic therapy is a simplified means of administering thrombolysis that facilitates rapid time to treatment. TNK-tissue plasminogen activator (TNK-tPA) is a highly fibrin-specific single-bolus thrombolytic agent. METHODS AND RESULTS: In TIMI 10B, 886 patients with acute ST-elevation myocardial infarction presenting within 12 hours were randomized to receive either a single bolus of 30 or 50 mg TNK-tPA or front-loaded tPA and underwent immediate coronary angiography. The 50-mg dose was discontinued early because of increased intracranial hemorrhage and was replaced by a 40-mg dose, and heparin doses were decreased. TNK-tPA 40 mg and tPA produced similar rates of TIMI grade 3 flow at 90 minutes (62.8% versus 62.7%, respectively, P=NS); the rate for the 30-mg dose was significantly lower (54.3%, P=0.035) and was 65. 8% for the 50-mg dose (P=NS). A prespecified analysis of weight-based TNK-tPA dosing using median TIMI frame count demonstrated a dose response (P=0.001). Similar dose responses were observed for serious bleeding and intracranial hemorrhage, but significantly lower rates were observed for both TNK-tPA and tPA after the heparin doses were lowered and titration of the heparin was started at 6 hours. CONCLUSIONS: TNK-tPA, given as a single 40-mg bolus, achieved rates of TIMI grade 3 flow similar to those of the 90-minute bolus and infusion of tPA. Weight-adjusting TNK-tPA appears to be important in achieving optimal reperfusion; reduced heparin dosing appears to improve safety for both agents. Together with the safety results from the parallel Assessment of the Safety of a New Thrombolytic: TNK-tPA (ASSENT I) trial, an appropriate dose of this single-bolus thrombolytic agent has been identified for phase III testing.     

A secondary prevention trial of antioxidant vitamins and cardiovascular disease in women. Rationale, design, and methods. The WACS Research Group

The evidence for a potential benefit of antioxidant vitamins in the prevention and therapy of atherosclerotic disease is derived from laboratory, clinical, and observational epidemiologic studies but remains inconclusive. Data from randomized clinical trials are sparse, particularly for women. Therefore, it is both timely and important to conduct large-scale primary and secondary prevention trials of antioxidants and cardiovascular disease (CVD). The Women's Antioxidant and Cardiovascular Study (WACS) is a randomized, double-blind, placebo-controlled secondary prevention trial of the balance of benefits and risks of antioxidant vitamins (vitamins E and C, and beta-carotene) among 8000 women with preexisting CVD. This secondary prevention trial will be conducted as a companion to the recently started Women's Health Study, a primary prevention trial of vitamin E and beta-carotene, as well as aspirin. In the WACS, US female health professionals aged 40 years and older with a history of myocardial infarction, angina pectoris, coronary revascularization, stroke, transient cerebral ischemia, carotid endarterectomy, or peripheral artery surgery will be randomly assigned, utilizing a 2 x 2 x 2 factorial design, to receive vitamin E, vitamin C, beta-carotene, and/or placebo. Cardiovascular end points include nonfatal myocardial infarction, nonfatal stroke, coronary revascularization procedures, and total CVD mortality. The present article describes the rationale, design, and methods of the trial.     

Aberrant cervical thymus: a case report and review of literature

This article illustrates a case of an aberrant cervical thymus presented as a neck mass. This is a case of a 4-month-old boy presenting with a right submandibular mass whose preoperative diagnosis was lymphangioma or neoplastic lesion. The mass was successfully removed and the histopathological examination showed normal thymic tissue with no diagnostic abnormality. This paper reviews the embryological background of aberrant cervical thymus, the varying clinical presentations with an emphasis on differential diagnosis, clinical work-up, and surgical treatment.