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This study was carried out to measure and compare the concentration of bacterial endotoxin in a variety of samples from drinking tap and bottled water available in Kuwait by using the Limulus Amoebocyte lysate test. A total of 29 samples were tested. Samples were collected from a variety of locations throughout the six governorates of Kuwait and 23 brands of local and imported bottled water samples were collected from the local market. The concentration of bacterial endotoxin was measured by using the standard Limulus Amoebocyte lysate test, gel clot method. This study showed that measured endotoxin concentrations in tap drinking water varied from 2.4 to 33.8 EU/ml with the average endotoxin concentration of 14.2 EU/ml. While the results of endotoxin concentrations in the bottled water were <0.03 to 20.1 EU/ml with an average of 1.96 EU/ml. The average concentration of endotoxin in bottled water is 13.5 % of the average concentration of endotoxin in tap drinking water. This experimental investigation has proved that drinking bottled water has less endotoxin as compared to tap water in Kuwait. It is also demonstrated that the endotoxin concentration did not exceed the acceptable level in drinking tap water.

Abstract. Verapamil, a Ca 2+ entry blocker, can induce bronchorelaxation and bronchoconstriction. The mechanism of verapamil-induced bronchoconstriction is poorly understood. The present study determines the direct effect of verapamil on smooth muscle of isolated ovine airways and analyzes the mechanisms involved. Isolated tracheal strips were suspended in organ baths containing Krebs solution for isometric tension recording. Tissue responses to verapamil as assessed by basal tone were examined in the presence or absence of epithelium. The effects of verapamil on carbachol and cooling-induced contraction were also recorded. Measurement of unidirectional fluxes was carried out using 45 Ca 2+ in the absence or presence of verapamil. Verapamil induced contractions of basal tracheal smooth muscle that were proportional to its concentrations. Removal of epithelium did not affect the verapamil contractile effect. Verapamilinduced contractions were abolished in Ca 2+ -free Krebs solution containing 2 mM EGTA. Verapamil increased the 45 Ca 2+ influx into the tracheal smooth muscle. It caused relaxation of the muscle tone induced by carbachol or KCl, but it potentiated the effect of cooling-induced contraction. Verapamil induced Ca 2+ influx that may lead to bronchoconstriction. These results proved that verapamil may worsen bronchoconstriction; therefore verapamil should be used with caution in asthmatic individuals.

The authors voluntarily retract their article from Environmental Monitoring and Assessment on the grounds that certain parts/portions of the article have been published elsewhere and were not appropriately referenced. The situation is due to honest error and the authors would like to apologize for any inconvenience this may have caused to the readers.