PubMed Health⌕ Search

Biomedical subjects

M A Fernando

Publications and source records attributed to M A Fernando.

At least 73 records · Page 4Linked to original sources
PubMed1977

Isolation of host-cell nuclei from chick intestinal cells infected with second-generation schizonts of Eimeria necatrix.

A procedure is described for the preparation of purified nuclei of chick intestinal cells infected with Eimeria necatrix. During second-generation schizogony the host-cell membrane becomes resistant to homogenization, hypotonic shock and ultrasonication. However, brief treatment with a low concentration of trypsin (0.001%) will disrupt the cell membrane. Thereafter the nuclei can be selectively harvested from contaminating nuclear types and schizonts by a series of centrifugations. Electron microscopy and Feulgen-DNA microspectrophotometry showed that the nuclear preparations retained their integrity with little, if any, loss of DNA. Chemical determinations confirmed that host-cell nuclear DNA synthesis was stimulated by coccidial infection and further established that quantitatively there was a coincident increase in the amount of host nuclear RNA during schizogony. It is now feasible to examine directly the effects of coccidial infection upon the host's nuclear apparatus.

Animals↗
PubMed1977

Drug resistance in coccidia: a robenidine-resistant strain of eimeria tenella.

Tests for resistance to a recently introduced anticoccidial drug, robenidine, were performed on a strain of Eimeria tenella recovered from broiler chickens infected with acute cecal coccidiosis. The strain was identified previously and again confirmed by the timing of mortality of the infected chickens (five to six days postinfection), the appearance of lesions and parasites in ceca only, and the measurements (21.6 +/- 1.9 micron X 19.8 +/- 2.4 micron) of the oocysts. The tests showed that the strain of E. tenella could establish infections in chickens medicated with fourfold the recommended level of robenidine in feed but no oocysts could be recovered from the feces of infected chickens when the level of drug was increased to eightfold. The decrease in mortality, in the severity of lesions and oocyst output and the increase in the average weight gain of infected chickens followed closely the increase in the level of robenidine in feed. In contrast, no infections were found in chickens infected with a sensitive strain of E. tenella and maintained on feed mixed with the recommended level of robenidine. This and other findings discussed here show that resistance to robenidine is developing in coccidia commonly found in broiler houses.

Animals↗
PubMed1975

The development of the lesions caused by second generation schizonts of Eimeria necatrix.

First generation merozoites of Eimeria necatrix were found in epithelial cells of the crypts of Lieberkühn of chicks cells appeared to migrate into the lamina propria, forming nests of second generation schizonts that extended from the external muscularis to the lamina propria of the mid-villus. On the fourth and fifth days the mature schizonts, usually still within the infected cells were dishcarged into adjacent crypts. The muscularis mucosa appeared to be repaired by the formation of new, smooth muscle cells that spliced the broken ends of the ruptured muscle. 'Ghosts' of schizonts were found in the lamina propria on the sixth day after infection.

Animals↗
PubMed1975

Effect of Eimeria acervulina infection on nutrient retention with special reference to fat malabsorption in chickens.

Nutritional balance studies were conducted to determine the effect of Eimeria acervulina infection on the retention of nutrients and the efficiency of utilization of protein and energy in the diet during the course of intestinal coccidiosis in chickens. Both light and electronmicroscopic studies were conducted to elucidate the pathogenesis of fat malabsorption in the infected chickens. The infection with E. acervulina during the acute phase of the disease (day 4 to day 8 postinfection) caused a reduction (P smaller than 0.01) in the retention of percent protein, percent ether extract and percent gross energy of the diet with a concomitant increase (P smaller than 0.01) in the concentration of ether extract and gross energy of the excreta. The metabolizable energy value of the diet was also depressed during this phase. During the recovery phase of the disease (day 9 to day 13 postinfection) infected chickens voided excreta containing a slightly greater concentration of ether extract when compared to the controls but differences in the retention of percent protein and percent gross energy were no longer observed. An increased retention of percent phosphorus also occured during the recovery phase. Studies involving the carcass composition revealed that the efficiency of utilization of protein and metabolizable energy of the diet for tissue deposition was reduced (P smaller than 0.05) during day 0 to day 8 postinfection but only the efficiency of metabolizable energy utilization was found to be depressed (P smaller than 0.05) when data for day 0 to day 14 postinfection were analyzed. Both light and electronmicroscopic studies of the duodenal villi of infected chickens during day 5 to day 6 postinfection revealed accumulation of large globules of fat in the villus epithelial cells parasitized by the gammonts of E. acervulina indicating a possible blackade of "fat exit" from these cells.

Animal Feed↗