Summary1. No species differences between Schistosoma haematobium and Schistosoma mansoni were detected when the 150 of metrifonate for the acetylcholinesterases (AChE) and the cholinesterases (ChE) of these two trematodes were determined in isolated enzyme preparations or following exposure of the intact worms to this drug in vitro. 2. S. haematabium appeared to be more affected by AChE inhibition because, after administration of metrifonate to hamsters, a hepatic shift of the parasites was observed with a dose of metrifonate (150 mg (0-6 mmol) per kg) which produced no shift of S. mansoni, although AChE inhibition was comparable in both species. 3. Administration of a possible metabolite of metrifonate, dichlorvos, to hamsters resulted in a greater inhibition of AChE and ChE activities of S. haematobium than those of S. mansoni. Furthermore, when schistosomes were incubated with dichlorvos, inhibition of AChE activity of female S. haematobium was significantly greater (P<0 005) than that of both sexes of S. mansoni and of male S. haematobium. 4. The discrepancy between the lack of a significant chemotherapeutic effect of metrifonate in hamsters infected with S. haematobium and the clinical results obtained with this organophosphorus compound in human schistosomiasis haematobium is discussed, and the need to conduct similar studies in primates is pointed out.
Following the administration of relatively high doses of the antischistosomal drug hycanthone to mice and hamsters infected with Schistosoma mansoni, a number of the worms survived. After a period of 6 to 12 months these parasites resumed production of viable eggs that gave rise to schistosomes that proved resistant to hycanthone and to two other related antischistosomal compounds. This drug resistance has remained stable for three subsequent generations of worms.
Hospitalized patients who received clindamycin or ampicillin were evaluated for gastrointestinal side effects for a period of up to six weeks after therapy was discontinued. Of 104 patients receiving clindamycin therapy, 31 (29.8%) developed diarrhea, and two (1.9%) developed pseudomembranous colitis (PMC). Of 138 patients receiving ampicillin, 24 (17.3%) developed diarrhea, and one (0.7%) developed PMC. Diarrhea persisting for three days or more was noted in 13 (12.5%) of the patients receiving clindamycin and in seven (5.1%) of those receiving ampicillin. The tendency to develop diarrhea was positively correlated with serious illness, abdominal or pelvic sepsis, and total dosage of clindamycin. Examination of stools from a patient with PMC that was associated with clindamycin therapy showed a decrease in the number of anaerobic bacteria from the numbers found in stool cultures of normal controls. Those patients who did not develop diarrhea also had fewer anaerobic bacteria and coliform organisms. Lymphocytes from the patient with PMC were hyporeactive to phytohemagglutinin and hyperreactive to clindamycin.
The bursa compulatrix of the Monarch butterfly was investigated utilizing light microscopy, histochemistry, and scanning and transmission electron microscopy in order to relate its morphology to the release of sperm from the spermatophore. The bursa has a row of large chitinous teeth on either side of the organ. The dorsal and ventral surfaces are covered with chitinous plates, the plates having bristles on one side. A single layer of cells lies under both the plates and teeth, one columnar cell under each plate, one cuboidal cell under each tooth. The toothed area has no muscle cells. However, the dorsal and ventral hemispheres of the bursa each have a crescent-shaped packet of muscle fibers that traverse the organ; there are no longitudinal fibers. Spermatophores with thick walls were found in the bursal lumen. Morphological evidence suggests that the presence of the spermatophores is sensed by the bristles and that the packets are opened by contraction of the muscles bringing the large teeth into contact with the spermatophore wall.
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