Current research suggests that head lice resistance exists, but little is known regarding the actual incidence of this resistance or whether this incidence is increasing. More research is needed to assess the status of this problem. Proposed mechanisms for head lice resistance include knock-down resistance, glutathione S-transferase-based resistance, and monooxygenase-based resistance.
A case report of a 15-year-old adolescent male who developed a hypersensitivity reaction to a parenteral nutrition (PN) solution containing multivitamins (MVI) is presented. Within 30 minutes after initiation of PN and lipids, the patient developed a total-body pruritic urticarial rash that resolved after discontinuation of the infusions and administration of diphenhydramine. Rechallenge with the same PN solution excluding heparin, as well as lipids, resulted in a similar urticarial reaction that also resolved within 30 minutes after discontinuation of the infusions and administration of diphenhydramine. Another rechallenge with a solution containing dextrose and amino acids at the same concentrations contained in the original PN solution did not elicit an allergic reaction, whereas addition of MVI to the dextrose and amino acids resulted in a similar allergic reaction 20 minutes after the start of the infusion. It was determined that the MVI component of the PN was the most likely causative agent of this patient's urticarial reaction.
United Chrome Products, Inc. (Corvallis, OR), discharged liquid chrome-plating wastes into an on-site dry well from 1957 to 1977. Samples were collected from ground and surface waters during February and December 1984 and evaluated for toxicity potential using 96-h Selenastrum capricornutum bioassays. Bioassays of the February samples were used to calculate predicted EC50 values for different chromium concentrations, which %ere then compared with the chromium concentrations measured in the December samples and with the results of S. capricornutum bioassays on these samples. An excellent correlation was obtained between the predicted EC50 values and the actual bioassay response values for ground water and drainage ditch samples. However, no correlation was obtained with the off-site surface water samples. These results could not be explained by changes in chromium valence, and they demonstrate that, even in simple systems, toxicity cannot readily be predicted based solely on chemical analysis.
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