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Biomedical subjects

R O Gilbert

Publications and source records attributed to R O Gilbert.

54 records · Page 3Linked to original sources
PubMed1987

The transmission of bluetongue virus by embryo transfer in sheep.

The susceptibility of sheep to intrauterine infection with bluetongue virus (BTV) was established by introducing 10(4) plaque-forming units of BTV type 10 into the uterine lumen of two seronegative ewes in a simulated embryo transfer operation. Both ewes became viraemic and underwent seroconversion to BTV. Embryos recovered from seronegative superovulated donor ewes were incubated in vitro for 8 h with BTV type 10. After incubation the embryos were thoroughly rinsed by repeated transfer to sterile culture medium, and 12 of these embryos were then transferred to the uterus or oviduct of seronegative, synchronized recipients. Viraemia and seroconversion were detected in nine recipient ewes. Embryos recovered from eight viraemic ewes were transferred to 15 seronegative, synchronized recipients. Viraemia and seroconversion were detected in 2 of the recipients, both of which also became pregnant. A lamb born to a ewe becoming infected at the time of embryo transfer was clinically normal, and no evidence of BTV infection was obtained at postmortem examination of the lamb after slaughter.

Journal Article↗
PubMed1987

Successful surgical repair of a vascular shunt of the corpus cavernosum penis and penile fibropapillomata in a bull.

A single vascular connection between the corpus cavernosum penis and the superficial penile vasculature was diagnosed in an 18-month old Holstein bull with a history of acquired failure to maintain penile erection. Previously normal serving ability had been documented. Multiple penile fibropapillomata were also found. The vascular shunt was identified by contrast cavernosography and ligated, and the fibropapillomata excised. The bull returned to normal function within three months after surgery, and no recurrence of either problem had been experienced by 12 months after surgery.

Animals↗
PubMed1985

Successful transfer of embryos recovered from a cow with chronic cervicitis of mixed aerobic and anaerobic bacterial aetiology a case report.

An imported 13-year-old Simmentaler cow was presented with severe purulent cervicitis and endometritis from which Corynebacterium pyogenes , Fusobacterium necrophorum , Bacteroides melaninogenicus and an untyped Clostridium perfringens were isolated. The endometritis responded to treatment but the cervix did not and remained fibrous, continuously patent and purulent. Natural pregnancy was considered unlikely and the cow was prepared as an embryo transfer donor. Eight embryos were recovered and six transferred, resulting in five confirmed pregnancies and four live births.

Journal Article↗
PubMed1984

The effect of thawing temperature on post-thaw longevity of frozen bovine semen.

Bovine semen, diluted with a skimmed milk, 10% egg yolk, 7% glycerol extender and frozen in 0,25 ml French straws, was thawed in water at 5 degrees C, 20 degrees C or 35 degrees C for 20 seconds and then incubated at 37 degrees C. Specimens were examined periodically for motility. Semen thawed at 35 degrees C maintained motility for longer than that thawed at lower temperatures. Attempts to duplicate these findings in vivo were inconclusive but tend to correlate in vitro findings.

Animals↗
PubMed1973

Radiation effects in free-ranging pocket mice, Perognathus parvus, during the breeding season.

Captive and free-ranging Great Basin pocket mice, Perognathus parvus, were exposed to ionizing radiation during the breeding season, April-June, in 1971. The values for the median lethal dose (LD(50)) at 30 days plus or minus the standard deviation were 880 +/- 14 rads and 780 +/- 27 rads, respectively, and the slopes of the survivorship curves were significantly different. These differences suggested that there was a synergism between radiation-induced and environmental sources of mortality, since the field data were corrected for natural mortality (5 percent) in the controls.

Animals↗
PubMedDate not supplied

Leukocytic invasion of the ovine cervix at parturition.

OBJECTIVE: The aim of this study was to use the activity of a leukocyte-specific enzyme, myeloperoxidase, to quantify changes in leukocyte concentration in the ovine cervix during pregnancy. METHODS: Cervical tissue was collected under halothane general anesthesia from 26 sheep at different stages of gestation, in the nonpregnant state, and postpartum. Myeloperoxidase activity was used to assess the degree of leukocytic infiltration of the tissue. RESULTS: Myeloperoxidase activity was low in cervices from nonpregnant ewes and did not increase during pregnancy until the onset of labor. Myeloperoxidase activity decreased after parturition. CONCLUSION: Labor in sheep is associated with leukocytic invasion of the cervix. This observation suggests that leukocytes could participate in cervical connective-tissue reorganization during dilatation at parturition and in postpartum involution of the cervix in the species.

Animals↗
PubMedDate not supplied

An outcrossed canine pedigree for linkage analysis of hip dysplasia.

Canine hip dysplasia (CHD) is a prevalent, debilitating, polygenic disease characterized by hip subluxation and laxity which results in osteoarthritis. We are developing an informative pedigree for linkage analysis of CHD. The seven greyhound founders had excellent hip conformation with high dorsolateral subluxation scores (percentage of femoral head covered by the dorsal acetabulum in a weight-bearing position) of 66 +/- 4% (mean +/- SD averaged over both hips) and low hip distraction (laxity) indices of 0.14 +/- 0.08. Nine greyhounds bred on site had radiographic evidence of ossification in the capital femoral chondroepiphysis at 7.7 +/- 0.9 days of age. At 8 months of age they had a mean distraction index of 0.24 +/- 0.08 and dorsolateral subluxation score of 76 +/- 1%. Of the four dysplastic Labrador retriever founders, three had mean age at onset of capital femoral chondroeplphyseal ossification of 20 +/- 7 days of age n = 3) and a mean distraction index of 0.46 +/- 0.1 accompanied by hip osteoarthritis. Thirty-four F1s had mean onset of capital femoral ossification (10.7 +/- 4.0 days of age) and mean dorsolateral subluxation scores (61 +/- 12%) similar to the greyhound founders, but distraction indices (0.42 +/- 0.2) more similar to the Labrador retriever founders. One F1 had CHD radiographically but none of 20 F1s had osteoarthritis at necropsy at 10 months of age. These data suggested that maximum passive laxity (as measured by the distraction index) and normal osseous conformation (as indicated by a high dorsolateral subluxation score) were both dominant traits and were controlled by separate quantitative trait loci (QTL). Forty-three back-crosses between F1s with the highest hip laxity and greyhound founders had mean onset of capital femoral ossification at 9.9 +/- 2.6 days of age. Of 10 dogs in the backcross generation that have reached 8 months of age, 2 had palpable subluxation without marked CHD radiographically. The mean distraction index of these dogs was 0.36 +/- 0.16 and the dorsolateral subluxation score was 65 +/- 5%. Although dogs in the backcross generation that were three-quarter greyhound had a broad range of hip laxity, a protective effect of the greyhound QTLs for good osseous conformation has mitigated thus far against subluxation and CHD.

Animals↗
PubMedDate not supplied

Genetic structure of susceptibility traits for hip dysplasia and microsatellite informativeness of an outcrossed canine pedigree.

An outcrossed canine pedigree was developed for quantitative trait locus (QTL) mapping of hip dysplasia by breeding dysplastic Labrador retrievers to trait-free greyhounds. Measured susceptibility traits included age at onset of femoral capital chondroepiphyseal ossification (OSS), maximum hip distraction (laxity) index (DI), and the dorsolateral subluxation (DLS) score. The pedigrees consisted of 147 dogs representing four generations. For 59 dogs genotyped with 65 microsatellites, the median heterozygosity and polymorphic information content (PIC) values of the F(1) generation were 0.82 and 0.68, respectively. Seventy-seven percent of microsatellites had a PIC greater than 0.59 in the F(1)s. Ninety-six percent of alleles showed Mendelian inheritance. Based on marker informativeness, approximately 350 randomly selected markers would be required for genome-wide screening to obtain an average interval between informative markers of 10 cM. Heritability was estimated as 0.43, 0.5, and 0.61 for OSS, DI, and the DLS score, respectively. Biometric estimates of the mean (+/- variance) effective number of segregating QTLs was 1.2 (+/- 0.05), 0.8 (+/- 0.02), and 1.0 (+/- 0.03) for OSS, DI, and the DLS score, respectively. The distributions of simulated backcross trait data suggested that the loci controlling these traits acted additively and that the DI may be controlled by a major locus. When combined with previous power and quantitative genetic analyses, these estimates indicate that this pedigree is informative for QTL mapping of hip dysplasia traits.

Animals↗
PubMedDate not supplied

Tube cystostomy for treatment of obstructive urolithiasis in small ruminants.

Tube cystostomy was used to treat 13 goats and two sheep with obstructive urolithiasis. The cystostomy tube was intermittently occluded 3 to 4 days after placement to determine if urine could be voided through the urethra. If the animal showed no discomfort during urination after the cystostomy tube had been occluded for several days, the tube was removed. This procedure was successful in relieving urethral obstruction in 12 animals. The mean time until the animal could urinate freely and until the cystostomy tube was removed was 11.5 and 14.4 days respectively. Follow-up was available for 10 animals; seven were alive with no recurrence of urinary obstruction. One goat died from unrelated to urinary obstruction 1 year postoperatively. One goat died from unknown causes, and one goat died after urinary obstruction recurred.

Animals↗
PubMedDate not supplied

Myeloid and megakaryocytic hypoplasia in related standardbreds.

Myeloid and megakaryocytic bone marrow hypoplasia in association with moderate to profound neutropenia was observed in 8 young Standardbred horses sired by the same stallion; 7 horses were intermittently thrombocytopenic. Evaluation of serial neutrophil counts in 2 horses suggested that a cyclic variation in neutrophil numbers was present, that lymphocyte numbers increased when neutrophil counts decreased, and that platelet counts decreased when neutrophil counts decreased. Preliminary bone marrow cultures indicated that myeloid progenitor cells were present and that these cells were able to respond to exogenous growth factors by differentiating. A bone marrow microenvironment or growth factor defect is suspected. Seven of 8 horses died or were euthanized. One horse with moderate neutropenia and a normal platelet count has been racing for 3 years. Necropsies in 4 horses did not reveal a cause for the myeloid hypoplasia. A familial basis for the disease is suspected.

Anemia, Aplastic↗
PubMedDate not supplied

A field study on estrus detection in lactating beef cattle.

Estrus detection efficacy and heat detection protocol were studied by means of a field study carried out on 878 lactating beef cows in 60 French herds. Average herd size was 48, and 75% of the farmers partly or exclusively used artificial insemination. The cows were calved between October 1992 and March 1993. Estrus was recorded daily by the farmers. Cycling status was determined by progesterone radioimmuno-assay 2 months after calving. The relationship between the estrus detection protocol and the delay period from calving to first observed estrus was analysed using survival curves and the Cox proportional hazard model, adjusting for confounders. Seventy-one percent of the cows were seen in estrus by the farmers; the interval between calving and the first observed estrus ranged from 9 days to more than 5 months and the median was 56 days. Two months after calving, 44% of the cycling cows had not been seen in heat by the farmers and 11% of the non-cycling cows had been reported to have been in estrus. The heat detection protocol varied widely between farmers, depending on the considered estrus signs, schedule and time spent looking for signs. Two factors were significantly related to a shorter interval from calving to first observed heat: the use of artificial insemination (which relates to the farmer's interest in heat detection) and an overall daily time spent for heat detection greater than 1 h. Cows in tie stalls had a delayed interval to the first observed estrus. These results show that many farmers did not adapt their reproduction practice sufficiently to an earlier calving period. There is room for improvement since in many cases the heat detection protocol does not match the required standards for optimal heat detection.

Anestrus↗