Consistent in vitro behavioral patterns were found in the scolex and strobila of adult Hymenolepis diminuta. These patterns were measured with a force transducer and the behavior analyzed with a slow motion closed circuit T.V. Varying concentrations of serotonin (5-HT), acetylcholine (Ach), histamine and somatostatin, in the range of 10(-3) to 10(-9) M, were tested for their influence on the rhythmic patterns of behavior. High concentrations of 5-HT and of Ach decreased scolex motility. While 5-HT significantly increased motility in the anterior-, mid- and posterior regions of the strobila at 10(-3) M, Ach inhibited motility in all 3 regions of the strobila at the same concentrations. At high concentrations, somatostatin had a smaller stimulatory effect on worm motility in the anterior and mid-regions; histamine only significantly affected worm motility in the posterior region of the strobila. Depending on concentration, the action of 5-HT, Ach and histamine can be reversed, particularly in the anterior and posterior regions of the strobila. The in vivo assay for worm migrational responses suggests that the action of the neuromuscular stimulators and inhibitors on worm migration is indirect.
Representative facultative anaerobes of the bacterial flora from the intestine of female Ascaris suum were isolated and identified. The number of bacteria in the intestine was approximately 4 X 10(9) per g wet weight of intestine. Seventeen of 19 of the isolated colonies were found to secrete 5-hydroxytryptamine in culture. Holding A. suum in an antibiotic-containing medium did not affect the levels of 5-hydroxytryptamine in the worm, which were 231 +/- 14 ng/g in antibiotic-media as compared to 250 +/- 16 ng/g in control media. This implied that the bacteria may not be contributing to the level of 5-hydroxytryptamine in the tissues of A. suum.
Histological examination of the small intestine of mice infected with Heligmosomoides polygyrus indicates that the final site of the larvae is in the circular muscle layer of the muscularis externa of the anterior small intestine. The larvae become embedded in the muscle between the first and third days after infection and are subsequently sequestered by a localized leucocytic response. There is no evidence of a true cyst. Histological evidence suggests that the larvae actively feed on the tissues of the host during their development.
Our earlier studies had demonstrated that inhibition of DNA methylation following carcinogen treatment potentiated initiation of the carcinogenic process in the rat liver system. The hepatic nodules developed by initiation-promotion protocols showed a characteristic hypomethylation in the cell-cycle-related genes c-fos, c-myc and c-Ha-ras. In the present study we have found that the gene for beta-hydroxy-beta-methyl glutaryl coenzyme A reductase, a major rate-limiting enzyme in the biogenesis of mevalonate, is also hypomethylated at both CCGG and GCGC sites and expressed in hepatic nodules. This gene, however, did not exhibit hypomethylation in CCGG sequences in non-nodular surrounding liver, livers from rats subjected to two-thirds partial hepatectomy, or exposed to initiator alone (1,2-dimethylhydrazine given 18 h after partial hepatectomy) or to diets containing 1% orotic acid alone (promoting regimen). The activity of the enzyme and mevalonate formation are positively correlated with DNA synthesis and cell proliferation--two key components of the carcinogenic process. Taken together, the results suggest that hypomethylation of specific genes occurs in the carcinogenic process and this altered pattern of DNA methylation may play a role in the growth of the nodules.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.