Biomedical subjects

A Samizadeh-Yazd

Publications and source records attributed to A Samizadeh-Yazd.

3 recordsLinked to original sources

PubMed1979

The longevity and hatchability of Philophthalmus megalurus and P. gralli miracidia in different environmental conditions.

The effects of salinity, pH, and temperature on the longevity and hatchability of miracidia of Philophthalmus megalurus and P. gralli were determined. Miracidia of both species are able to hatch and survive at saline concentrations much above physiological levels, although these processes are reduced in 2.0--2.4% saline and completely inhibited at 2.6%. The greatest hatching rates for both species were found near neutrality (pH 6--8) but some miracidia hatched at the extreme pH levels of 3 and 12. Philophthalmus megalurus miracidia exhibited longer half-lives under acid conditions (pH 2--6) than P. gralli miracidia; conversely, P. gralli miracidia showed longer half-lives in alkaline conditions (pH 8--11). Hatching and longevity were much greater below room temperature (5--20 C) than above (30--50 C) for miracidia of both species. Temperatures above 50 C proved lethal for eyefluke eggs. Except in acid pH, P. gralli miracidia showed longer half-lives than miracidia of P. megalurus. Comparison to studies on schistosomes revealed that the inhibitory effects of physiological saline and host body temperature on the hatching process of schistosome eggs does not occur in these 2 species of eyeflukes.

Animals↗

PubMed1979

Observations on the pathogenic effects of Nematodirus helvetianus in dairy calves.

Six Holstein-Friesian calves 3 to 5 months old, were used in a small-scale experiment to determine the pathogenic effects of the thread-necked strongyle Nematodirus helvetianus. Two calves were kept as controls and 4 were infected, 2 with single doses of 25,000, and 2 with 50,000 N helvetianus larvae. Observations made during the 8 weeks of the experiment found that N helvetianus is capable of producing severe pathologic changes in the intestine of previously healthy calves. At 38 days after infection, the calves infected with 25,000 and 50,000 larvae gained 32.9% and 72.4% less weight respectively, than their controls. An increase in total lymphocytes was observed with no significant change in hemoglobin concentration. Adult worms were found to penetrate the intestinal mucosa with considerable destruction, including tunneling. Rectal temperatures were elevated in infected animals. The prepatent period for N helvetianus in single infection was 18 to 19 days. A spontaneous expulsion of the adult parasites was observed in 1 of the calves exposed to 50,000 larvae. Worms recovered in this animal numbered 565, whereas the number of worms recovered in another calf infected with 50,000 larvae was 21,860.

Animals↗

PubMed1979

Ovine coccidiosis: comparison of the effects of monensin and aureomycin on lambs infected with coccidia.

Lambs naturally infected with mixed species of Eimeria were fed monensin (30 mg/kg of feed) and aureomycin (10 mg/kg of feed) separately and in combination. An evaluation was made of the efficacy of the treatments in the suppression of oocyst production. Comparisons were made of the parasitic damage to the intestinal surface. Performance of the lambs was measured by weight gains and feed efficiency. Monensin given separately or in combination with aureomycin produced decreases in oocyst counts that were not significantly different from those in the lambs given only aureomycin. Body weight gains and feed efficiency were best in the aureomycin-treated group, and less so in the monensin-treated and the control groups. Animals fed the monensin-aureomycin combination had the poorest weight gains and feed efficiency. Scanning electron microscopy indicated that the groups fed monensin or aureomycin separately had morphologically normal intestinal surfaces. This was in contrast to the control group and the group fed the monensin-aureomycin combination, wherein there was disrupted intestinal surface morphology.

Animals↗