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Biomedical subjects

R Fayer

Publications and source records attributed to R Fayer.

At least 127 records · Page 7Linked to original sources
PubMed1989

Specificity and cross-reactivity of hybridoma antibodies generated against Eimeria bovis sporozoites.

Spleens from mice immunized with Eimeria bovis sporozoites were removed and the cells fused with mouse myeloma cells to produce hybridoma cell lines (HCLs). The resulting HCLs were examined for antibody (HAB) production against E. bovis sporozoites using an indirect immunofluorescent antibody test on air-dried sporozoites. Four fusions resulted in the production of 19 HCLs that produced HABs to E. bovis sporozoites. These 19 HCLs were further tested for reactivity with cell culture-grown merozoites of E. bovis and Sarcocystis cruzi of cattle; sporozoites of Eimeria tenella from chickens, Eimeria meleagrimitis from turkeys, Eimeria papillata and Eimeria vermiformis from mice; and bradyzoites of S. cruzi from calves. Six HCLs produced HABs that reacted only with E. bovis sporozoites and were species specific/stage specific. Two HCLs produced HABs that reacted only with E. bovis sporozoites and merozoites, and were species specific/stage cross-reactive. Seven HCLs produced HABs that reacted with the sporozoites of the other Eimeria species examined and were species cross-reactive/stage specific. Four of the HCLs produced HABs that reacted with all organisms tested and were species cross-reactive/stage cross-reactive. The results of this study suggest the conservation of some antigens throughout developmental stages and genera of Eimeriorina.

Animals↗
PubMed1989

Efficacy of hyperimmune bovine colostrum for prophylaxis of cryptosporidiosis in neonatal calves.

Twelve neonatal calves were experimentally infected with oocysts of Cryptosporidium parvum. Six calves in group A fed hyperimmune colostrum at birth had significantly less diarrhea and shed oocysts for less time than did 6 calves in group B fed colostrum from cows that were not hyperimmune. Calves in group A had diarrhea for 0-4 days (means = 2.3 days), whereas calves in group B had diarrhea for 4-6 days (means = 5.0 days). Calves in group A shed oocysts for 4-9 days (means = 6.2 days), whereas calves in group B shed oocysts for 7-11 days (means = 8.5 days). These findings indicate that passive lacteal immunity conferred partial protection against cryptosporidiosis. Whether such protection was provided by the immunoglobulins that were highly elevated in the colostrum (greater than 1:200,000 for IgG1, IgM, and IgA) and constituted a large part of the circulating antibody in the calves, or by other biologically active factors, such as cytokines, is undetermined.

Animals↗
PubMed1989

Hyperimmune bovine colostrum neutralizes Cryptosporidium sporozoites and protects mice against oocyst challenge.

Activity of colostral whey, produced by a cow immunized with oocysts of Cryptosporidium parvum and found to provide prophylaxis against cryptosporidiosis in calves, was tested in 2 experiments. In one experiment BALB/c mice were given the immune whey (HW), whey from a nonimmunized cow (CW), or a balanced salt solution (HBSS) before, during, and after oral inoculation with oocysts of C. parvum. Significantly fewer (P less than 0.05) C. parvum were found in mice that received HW (undiluted, 1:20 or 1:50) than in those treated with similarly diluted CW or with HBSS. In the second experiment it was determined that protection was mediated by specific anti-sporozoite activity when significantly fewer (P less than 0.05) C. parvum were found in mice that received sporozoites treated with HW diluted 1:20 or 1:50 compared with mice that received sporozoites treated with similarly diluted CW or with HBSS.

Animals↗
PubMed1988

Influence of parasitism on plasma concentrations of growth hormone, somatomedin-C and somatomedin-binding proteins in calves.

A parasitic disease model (sarcocystosis) was used to study the effects of infection and associated plane of nutrition on GH and somatomedin-C (SM-C) patterns in plasma, and SM-C binding protein patterns in plasma from 4-month-old male Holstein calves. Calves, matched by age and rate of growth before the experiment, were divided into three treatment groups (n = 7). In the first (control), animals were uninfected and food was available ad libitum; in the second, animals were infected with Sarcocystis cruzi and food was available ad libitum. The third group consisted of uninfected animals pair-fed to the level of feed intake of the infected animals. Blood samples were obtained at various times after infection for analysis of the secretory patterns of GH (day 27 after infection, samples every 10 min for 6 h), SM-C (days 27, 35 and 58 after infection) or binding protein (day 42 after infection). Samples were analysed for GH and SM-C by radioimmunoassay. Relative molecular weights of binding proteins were assessed by elution patterns from gel permeation columns. Clinical signs of infection were manifest abruptly on day 26 after infection. Voluntary feed intakes of infected calves as a per cent of control calves were 18, 46 and 78 on days 27, 35 and 58 after infection respectively. Plasma GH concentrations were lower in infected and pair-fed than in control calves (P less than 0.05). Plasma SM-C concentrations were reduced in calves with diminished feed intakes and lower still in infected calves (P less than 0.05). Plasma SM-C was positively correlated with nitrogen retention across treatment groups (r = 0.81). Two classes of binding proteins differing in molecular weight were identified. The relative amounts of each binding protein in plasma were reduced during low feed intake with some differences in the endogenous saturation affected by infection. These data suggest that altered growth and metabolism in parasitized calves may arise in part from both nutritional and infection-mediated effects on the regulation of GH, SM-C and SM-C binding proteins.

Animals↗
PubMed1988

Lysates of Sarcocystis cruzi bradyzoites stimulate RAW 264.7 macrophages to produce tumor necrosis factor (cachectin).

Lysate of Sarcocystis cruzi bradyzoites induced RAW 264.7 macrophages to release a factor that killed L 929 cells. Rabbit antibody to murine tumor necrosis factor (TNF) inhibited this killing effect, indicating that the factor causing cell death was similar to TNF (also called cachectin). Based on the present findings we hypothesize that TNF mediates, at least in part, the disease associated with this parasitic infection.

Animals↗
PubMed1988

Experimental Sarcocystis hominis infection in cattle: lesions and ultrastructure of sarcocysts.

Five calves inoculated orally with 10(5)-10(6) sporocysts of Sarcocystis hominis from human feces were necropsied 10, 18, 24, 111, and 222 days postinoculation (DPI). Calves became febrile (greater than 40-41 C) between 10 and 24 DPI and developed mild anemia (packed cell volumes were reduced by 40% of initial values) between 29 and 57 DPI but otherwise remained clinically normal. Focal hepatitis, mesenteric lymphadenitis, and myocarditis were seen in calves at 10, 18, and 24 DPI. No stages of the parasite were found at any of these times except for a few merozoites in macrophages associated with myocardial lesions in the calf necropsied 24 DPI. Mature sarcocysts at 111 and 222 DPI were up to 950 microm long and their walls were up to 6 microm thick. They were found only in skeletal muscles. One immature sarcocyst was seen in the myocardium of the calf at 222 DPI.

Age Factors↗
PubMed1988

Sarcocystis induced abortion and fetal death.

There are many unanswered questions and observations that appear contradictory within the subject of how sarcocystosis affects fetal health. Some fetuses are infected and have lesions, others are unaffected. Some fetal placentas are infected and have lesions, others are unaffected. Some maternal placentomes are infected and have lesions, others are unaffected. Most pregnant animals have overt clinical illness at the time the fetus is affected, others do not. Several possible mechanisms have been hypothesized by which sarcocystosis may directly or indirectly affect fetal health.

Abortion, Veterinary↗
PubMed1988

Sarcocystis arieticanis and other Sarcocystis species in sheep in the United States.

Histological sections of tongues, esophagi, and diaphragms from 512 adult ewes from the northwest United States and Texas were examined for Sarcocystis spp. Sarcocysts were found in sections of 82.1% of 504 tongues, 44.4% of 478 esophagi, and 51.7% of 89 diaphragms. Sarcocystis tenella was the predominant species and was found in 430 (84.0%) sheep; S. arieticanis was found in 18 (3.5%) sheep. The mean number of S. tenella sarcocysts in tissue sections was approximately 10 times higher than that of S. arieticanis. The identification of S. arieticanis was confirmed by ultrastructural studies and by transmission to dogs. Macroscopic sarcocysts of S. gigantea were also found but were not quantitated in all sheep; sarcocysts of S. medusiformis were not observed.

Animals↗
PubMed1986

Distribution of Toxoplasma gondii tissue cysts in commercial cuts of pork.

Distribution of Toxoplasma gondii cysts in tissues used for human consumption was studied in 4 naturally infected pigs (acquired infections) and in 2 experimentally infected pigs. On the day of euthanasia, pigs with acquired toxoplasmosis had serum antibody titers of 160 to 1,280 against T gondii (modified agglutination test). Experimentally infected pigs were inoculated with 10,000 oocysts of the GT-1 strain of T gondii and were euthanatized 267 or 357 days after inoculation. On the day of euthanasia, the experimentally infected pigs had serum antibody titers of 16 and 32 against T gondii. Fifty- to 100-g specimens from each of 6 cuts of meat commercially used to prepare Boston butt, arm picnic, ham, tenderloin, spareribs, and bacon and from the tongue, heart, brain, liver, kidneys, and diaphragm were collected from each pig and were digested in acid pepsin solution. Washed sediment from the digest of each specimen was inoculated SC into mice (6 mice/organ). Toxoplasma gondii was isolated from tissues of the 4 pigs with acquired toxoplasmosis; T gondii was isolated from the arm picnic, Boston butt, and tongue of 3 pigs, from the ham, tenderloin, spareribs, diaphragm and heart of 2 pigs, and from the bacon and brain of 1 pig. Toxoplasma gondii was not isolated from the kidneys of the 4 pigs with acquired toxoplasmosis. Toxoplasma gondii was isolated from the arm picnic, Boston butt, ham, spareribs, bacon, tongue, diaphragm, heart, and brain of the 2 experimentally infected pigs, and from the kidneys of one of the experimentally infected pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Prevalence, transmission, and pathogenicity of Sarcocystis gigantea of sheep.

Between March and May 1983, tongues and esophagi of 355 adult ewes from Colorado and Idaho were examined for grossly visible sarcocysts. Sarcocysts of Sarcocystis gigantea were found in 35 sheep. Cats fed sarcocysts from these naturally infected sheep shed sporocysts in their feces. Two adult ewes and 12 lambs inoculated with 1,000 to 1,000,000 sporocysts were euthanatized at postinoculation days (PID) 146, 230, 265, 391, 721, and 882, and their tissues were fed to Sarcocystis-free cats. All inoculated sheep remained clinically normal except for mild pyrexia between PID 12 and 18. Sarcocysts first became grossly visible at PID 391 and sarcocysts from sheep first became infectious for cats at PID 230.

Animals↗
PubMed1986

Hematologic values in calves infected with Sarcocystis cruzi.

Calves were inoculated with 2 X 10(5) Sarcocystis cruzi sporocysts. Red cell mass decreased dramatically between Days 21 and 35 post-infection and plasma volume increased concurrently, so that blood volume did not change significantly. Mild reticulocytosis and increased pyrimidine 5' nucleotidase activity in erythrocytes occurred between Days 35 and 42. Antiglobulin tests with anti-bovine IgG, IgM and C3 were negative, with the exception of a positive test for C3 in 1 of 6 infected calves.

5'-Nucleotidase↗
PubMed1986

Enzyme immunoassay detection of immunoglobulin M and G antibodies to Cryptosporidium in immunocompetent and immunocompromised persons.

Cryptosporidium is a parasite of the human gastrointestinal tract and has a worldwide distribution. We developed a sensitive and reproducible enzyme immunoassay for detection of serum IgG or IgM to Cryptosporidium. For IgG, 13 of 15 patients with cryptosporidiosis and 26 of 26 patients with cryptosporidiosis and AIDS were positive, whereas 57 of 60 presumably uninfected individuals were negative. All three IgG-positive presumably uninfected individuals had been potentially exposed. Sensitivity and specificity of this assay was 95%. Patients without AIDS showed an early rise and fall of IgM and later elevation of IgG; some patients with AIDS produced IgM, and all produced IgG. Sera from 9 (20.9%) of 44 Ecuadorian children with diarrhea were positive for both IgM and IgG antibodies; 106 sera from persons with other parasitic illnesses showed a normal distribution for IgG antibody. These ELISA data show that patients without and with AIDS have serum antibody response to Cryptosporidium and suggest that exposure to or infection with Cryptosporidium is common.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Types of myofibers parasitized in experimentally induced infections with Sarcocystis cruzi and Sarcocystis capracanis.

Eighteen calves were orally inoculated with either 200,000 or 225,000 sporocysts of Sarcocystis cruzi. Eight goats were orally inoculated with 20,000 sporocysts of S capracanis. Calves and goats were euthanatized at various times after inoculation, and portions of their right and left biceps femoris, right and left longissimus dorsi, myocardium, and tongue were frozen at -150 C in precooled isopentane and stored at -70 C. Frozen sections of these muscles were stained with hematoxylin and eosin, modified Gomori's trichrome, nonspecific esterase, diphosphopyridine nucleotide tetrazolium reductase, and adenosinetriphosphatase at pH 10.4 and 4.6. Muscle from the same locations was fixed in 10% neutral buffered formalin, processed for paraffin embedding, sectioned, and stained with hematoxylin and eosin. Microscopic examination of both calf and goat tissue indicated that both type I and type II muscle fibers were equally infected and that infected myofibers showed no apparent damage other than displacement by sarcocysts. Occasionally, muscle fibers within the muscle spindles contained sarcocysts.

Animals↗
PubMed1986

Effect of irradiation on the viability of Toxoplasma gondii cysts in tissues of mice and pigs.

Muscles from tongue, heart, and limbs of 14 pigs inoculated orally with Toxoplasma gondii oocysts were irradiated with 10, 20, 25, and 30 krad of gamma (cesium-137 and cobalt-60) irradiation. Viability of T gondii cysts was assayed by feeding porcine muscles to T gondii-free cats and/or by inoculation of sediment from acid-pepsin digested porcine muscle into mice. Cats fed 500-g samples of muscles irradiated with up to 20 krad shed T gondii oocysts. Cats fed muscles irradiated with 25 or 30 krad did not shed oocysts. Mice were inoculated with 8 isolates of T gondii, and tissue cysts in their brains irradiated with up to 40 krad were infective to mice; however, there was a 10,000-fold reduction in the viability of organisms in tissue cysts irradiated with 40 krad, compared with that in nonirradiated cysts. At 50 krad of gamma irradiation, there were no detectable infective organisms in infected mouse brains.

Animals↗