The prevalence of Vibrio spp. in drinking water and environmental samples in Vellore South India.

The prevalence of Vibrio cholerae in drinking water, lakes and sewage outfalls during July and August 1996 in Vellore, India was determined. Drinking water samples were collected on single occasions from 12 sites in different geographic areas of the town where cholera had been reported. Samples of water, plankton and sediment were collected from fixed sites at three lakes on three occasions separated by at least 3 days during the course of the study. Samples from open sewers were taken from two representative sites in four areas of the town. Bacteria isolated from samples were identified by standard biochemical tests and isolated strains of V. cholerae tested for their ability to agglutinate O1 and O139 antisera. Water samples from lakes were also tested for the presence of V. cholerae O1 and O139 by fluorescent antibody staining. Non-O1, non-O139 strains of V. cholerae were detected in 41% of drinking water samples and 100% of water, sediment and plankton samples from the test lakes. Eighty-seven per cent of open sewers sampled contained viable non-O1, non-O139 V. cholerae. Fluorescent antibody staining gave positive results for V. cholerae O1 and O139 for all water samples from the three lake sites. Strains of Aeromonas spp. were isolated from 58% of drinking water samples and from 66% of sediment, 77% of plankton and 55% of water samples from lakes. All open sewers sampled contained Aeromonas spp. PCR amplification employing specific primers demonstrated that none of the non-agglutinating V. cholerae isolates contained the ctx operon. The non-O1, non-O139 V. cholerae isolates showed different patterns of antibiotic resistance to ampicillin, ciprofloxacin, chloramphenicol, tetracycline and trimethoprim.     

Antiplatelet agents aspirin and clopidogrel are hydrolyzed by distinct carboxylesterases, and clopidogrel is transesterificated in the presence of ethyl alcohol

Aspirin (acetylsalicylic acid) and clopidogrel are two major antithrombogenic agents that are widely used for the treatment and prevention of cerebro- and cardiovascular conditions such as stroke. Combined use produces enhanced therapeutic effect. Aspirin and clopidogrel both are esters, and hydrolysis leads to decreased or inactivated therapeutic activity. The aim of the study was to determine whether aspirin and clopidogrel are hydrolyzed by the same enzyme(s), thus reciprocally prolonging the antithrombogenic activity. To test this possibility, microsomes from the liver and intestine were assayed for the hydrolysis of aspirin and clopidogrel. In contrary to the hypothesis, aspirin and clopidogrel were hydrolyzed in a tissue-differential manner. Liver microsomes hydrolyzed both drugs, whereas intestinal microsomes hydrolyzed aspirin only. Consistent with the tissue distribution of two carboxylesterases human carboxylesterase (HCE) 1 and HCE2, recombinant HCE1 hydrolyzed clopidogrel, whereas recombinant HCE2 hydrolyzed aspirin. In addition, hydrolysis of clopidogrel among liver samples was correlated well with the level of HCE1, and hydrolysis of aspirin with HCE2. Certain natural variants differed from the wild-type enzymes on the hydrolysis of aspirin or clopidogrel. In the presence of ethyl alcohol, clopidogrel is converted to ethyl clopidogrel. Carboxylesterases are important pharmacological determinants for drugs containing ester linkages and exhibit a large interindividual variation. The isoform-specific hydrolysis of aspirin and clopidogrel suggests that these two antithrombogenic agents may have pharmacokinetic interactions with different sets of ester drugs, and the altered hydrolysis by polymorphic mutants provides a molecular explanation to the interindividual variation.     

Morphology of flexor digitorum accessorius muscle

Purpose  

Muscle flexor digitorum accessorius is the muscle of the second layer of the sole. It arises by two heads and gets inserted into the tendon of flexor digitorum longus muscle. A variant of this muscle has often been incriminated in causation of tarsal tunnel syndrome. The action and phylogenetic importance of this muscle remains a matter of disagreement among different researchers. The present study was planned to study the morphology of this muscle in human.     

Highly selective synthesis of conjugated dienoic and trienoic esters via alkyne elementometalation-Pd-catalyzed cross-coupling

All four stereoisomers (7-10) of ethyl undeca-2,4-dienoate were prepared in ≥ 98% isomeric purity by Pd-catalyzed alkenylation (Negishi coupling) using ethyl (E)- and (Z)-β-bromoacrylates. Although the stereoisomeric purity of the 2Z,4E-isomer (8) prepared by Suzuki coupling using conventional alkoxide and carbonate bases was ≤ 95%, as reported earlier, the use of CsF or (n)Bu(4)NF as a promoter base has now been found to give all of 7-10 in ≥ 98% selectivity. Other widely known methods reveal considerable limitations. Heck alkenylation was satisfactory for the syntheses of the 2E,4E and 2E,4Z isomers of ≥ 98% purity, but the purity of the 2Z,4E isomer was ≤ 95%. Mutually complementary Horner-Wadsworth-Emmons and Still-Gennari (SG) olefinations are also of considerably limited scopes. Neither 2E,4Z nor 2Z,4Z isomer is readily prepared in ≥ 90% selectivity. In addition to (2Z,4E)-dienoic esters, some (2Z,4E,6E)- and (2Z,4E,6Z)-trienoic esters have been prepared in ≥ 98% selectivity by a newly devised Pd-catalyzed alkenylation-SG olefination tandem process. As models for conjugated higher oligoenoic esters, all eight stereoisomers for ethyl trideca-2,4,6-trienoate (23-30) have been prepared in ≥ 98% overall selectivity.