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Biomedical subjects

P M McCue

Publications and source records attributed to P M McCue.

12 recordsLinked to original sources
PubMed1997

Cryopreservation procedures for Day 7-8 equine embryos.

Larger grade 1 or 2 (1 = excellent,.... 4 = degenerate) equine embryos that ranged in diameter from 300 to 680 microm and were recovered from mares on Day 7 or 8 after ovulation, were randomly assigned to 3 widely divergent cryopreservation treatments. Treatment 1 consisted of cooling from -6 degrees C to -35 degrees C at 0.5 degrees C per min followed by plunging into liquid nitrogen, with a one-step addition and a 4-step removal of 1.0 M glycerol. Treatment 2 (step-down equilibration) consisted of a 2-step addition of glycerol to 4.0 M followed by a decrease to 2.0 M prior to freezing, with galactose present in the final step and in all glycerol removal steps and with a cooling protocol identical to Treatment 1. Treatment 3 was a standard vitrification protocol with step-wise addition of ethylene glycol up to 11.9 M, and step-wise removal of cryoprotectant with decreasing concentrations of galactose in the dilution medium. The cryoprotectants were removed at 20-21 degrees C. After the final dilution, the embryos were cultured in 5% CO2-in-air for 36 h at 38.5 degrees C on equine oviductal epithelial cell monolayers. Their morphology was then evaluated, their capsules were removed mechanically, and they were fixed prior to staining with 1% w:v orcein in 45% acetic acid to assess the morphology of their nuclei and cytoplasm. All 7 embryos in Treatment 1 degenerated during thawing or culture. Of the 6 embryos included in Treatment 2, 4 were graded 1, one was graded 2 and one graded 3 after culture in vitro. Of the 7 embryos in Treatment 3, one was graded 2, one was graded 3 and the remaining 5 were degenerate (P<0.01 among treatments). The average changes in initial diameter exhibited by the frozen/thawed embryos during culture after thawing were: Treatment 1, -91 microm; Treatment 2, +179 microm; Treatment 3, +20 microm (P<0.05). Two 26-day pregnancies were established following transfer of 6 Treatment 2 embryos (step-down equilibration method) to recipient mares.

Animals↗
PubMed1996

Superovulation.

Development of a superovulation technique that is successful, safe, and commercially available would revolutionize the equine breeding industry. However, the reality is that ovulation rates for mares following existing superovulatory treatment are much lower than for cattle. This dichotomy has been attributed to the relatively limited area available in the ovulation fossa for ovulation to occur, combined with the large size of the equine preovulatory follicle. In addition, the number of ovulations in the mare may be limited physiologically by the size of the follicular cohort that may be rescued by administration of gonadotropins. Clearly, additional research effort is necessary to optimize superovulation treatment regimens in the mare.

Animals↗
PubMed1994

Localization of aromatase in equine Leydig cells.

Stallion testes secrete large amounts of estrogens, but the cellular location of the enzyme that converts androgens to estrogens, cytochrome P450 aromatase, has not been determined. The goal of the present study was to immunocytochemically localize stallion testicular aromatase using a polyclonal antibody generated against human placental cytochrome P450 aromatase. Testes were obtained from 12 stallions from 2 to 23 years of age, during both the breeding and non-breeding seasons. Immunoreactivity was confined to the Leydig cells in all testes examined. No immunostaining was observed in the Sertoli or germ cells. Heterogeneity in the level of immunostaining among individual Leydig cells was observed. The results of this study indicate that in postpubertal, adult, and aged stallions, testicular aromatase is located in Leydig cells.

Animals↗
PubMed1994

Inhibin activity in the mare and stallion.

An overnight double antibody RIA, employing a rabbit antiserum raised to bovine 31 kDa inhibin (rAs-#1989, NICHD) and purified bovine 31 kDa inhibin (bINH-I-90/1, NICHD) as trace and standard, was validated to measure immunoreactive inhibin (iINH) concentrations in equine peripheral plasma, follicular fluid (FF), ovarian vein (OV) plasma, testicular tissue extracts (TTE) and testicular vein (TV) plasma. The dynamic relationship of iINH and follicle stimulating hormone (FSH) was investigated during the estrous cycle of the mare and the annual reproductive cycle of the stallion. In the RIA, parallel dose-response curves were observed between the bovine inhibin standard and serial dilutions of equine FF, OV, TTE, TV and plasma. The average recovery of a known amount of purified bovine inhibin added to gelding plasma was approximately 100%. In the inhibin bioassay, serial dilution of equine FF and TTE were observed to be parallel to the bovine inhibin standard. A five-fold difference (p < 0.05) between jugular and gonadal vein plasma iINH concentrations was observed in the mare and an eight-fold difference (p < 0.05) was observed in the stallion. Plasma levels of iINH in ovariectomized mares or geldings were undetectable in the RIA. Concentrations of FSH, estradiol and iINH changed significantly in the mare during the estrous cycle (p < 0.05). Immunoreactive inhibin levels were highest (0.54 +/- 0.06 ng/ml) on the day of ovulation, declined rapidly following ovulation and reached a nadir (0.21 +/- 0.03 ng/ml) on day 7 post-ovulation. Plasma iINH and estradiol concentrations followed a similar profile and were found to be positively correlated (r = 0.7064; p < 0.01), whereas iINH and FSH levels demonstrated an inverse relationship (r = -0.7359, p < 0.01) throughout the estrous cycle. Concentrations of FSH were also inversely related (-0.8498, p < 0.01) with estradiol during the cycle. In the stallion, plasma iINH and FSH levels changed significantly during the year (p < 0.05). The iINH profile reflected seasonal changes in testicular activity, with highest concentrations in late spring (3.37 +/- 0.44 ng/ml) and lowest concentrations in the fall (2.21 +/- 0.33 ng/ml). Plasma concentrations of iINH were positively correlated (r = 0.7691, p < 0.01) with FSH concentrations throughout the year. In conclusion, a specific and sensitive RIA for iINH has been validated for plasma and biological fluids in the horse. Furthermore, the gonads appear to be the source of bioactive and immunoreactive inhibin as observed in other species.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Serum chemistry values of the endangered San Joaquin kit fox (Vulpes macrotis mutica).

Serum chemistry values were obtained from 64 adult San Joaquin kit foxes (Vulpes macrotis mutica) in western Kern County, California (USA). The goal of the study was to establish normal chemistry values for this endangered species. No significant differences were found for mean values of alanine aminotransferase (217.1 IU/l), alkaline phosphatase (44.2 IU/l), cholesterol (145.6 mg/dl), total protein (5.8 g/dl), creatinine (0.63 mg/dl), calcium (8.2 mg/dl), albumin (3.0 g/dl), glucose (129.2 mg/dl), amylase (196.8 IU/l), sodium (153.7 mEq/l) and phosphorus (5.42 mg/dl) between sexes or seasons. Significant differences were noted for aspartate aminotransferase, blood urea nitrogen and potassium between seasons. Possible disturbances in normal hepatic and renal functions were noted.

Animals↗
PubMed1992

Long-term cannulation of the ovarian vein in mares.

A cannulation technique was developed to collect blood samples from the ovarian vein of mares over an extended period. Ovarian venous cannulae placed in 4 mares remained patent for a mean (+/- SEM) duration of 36.8 (+/- 6.2) days. During mid-diestrus, concentrations of progesterone in the ovarian vein ipsilateral to the corpus luteum (1,663.8 +/- 238.8 ng/ml) were significantly (P less than 0.001) higher than concentrations measured in paired samples from the jugular vein (6.1 +/- 0.3 ng/ml). Concentration of estradiol in the ovarian vein ranged from a mean of 1,053.2 +/- 303.1 pg/ml during diestrus to 3,353.8 +/- 1,052.8 pg/ml during estrus, whereas values for 74% of samples collected concurrently from the jugular vein were near or below the sensitivity of the assay (10 pg/ml). Results of the study indicate that patent long-term ovarian vein cannulation can be achieved in mares. The cannulation technique provides access to important fundamental information on equine reproductive endocrinology, which to our knowledge, has not been available.

Animals↗
PubMed1991

Follicular and endocrine responses of anoestrous mares to administration of native GnRH or a GnRH agonist.

Thirty-seven seasonally anoestrous mares were divided into treatment and control groups and given 10 micrograms of native GnRH (GnRH) per hour using a peristaltic pump, or 10 micrograms GnRH agonist (GnRHa) twice daily, beginning on either 13 January, 13 February or 14 March. Treatment with GnRH was equally effective in inducing ovulation in January (4/5), February (4/5) and March (3/4). GnRHa treatment was more effective in inducing ovulation in February (4/5) and March (4/4) than in January (2/8). Peak luteinizing hormone (LH) concentrations in mares induced to ovulate with GnRH (7.4 +/- 1.5 ng/ml) were significantly higher than LH concentrations in mares induced to ovulate with GnRHa (1.8 +/- 0.2 ng/ml). Urinary oestrogen conjugate concentrations increased parallel to increases in follicular diameter during treatment. Ovulations induced by GnRH or GnRHa were followed by a normal luteal phase. All mares induced to ovulate in January and February returned to anoestrous following withdrawal of GnRH support. The results suggest that the efficacy of GnRHa in the induction of ovulation in anoestrous mares is influenced by season, whereas the efficacy of pulsatile GnRH administration is not affected by season.

Anestrus↗
PubMed1989

Guttural pouch tympany: 15 cases (1977-1986).

From 1977 to 1986, guttural pouch tympany was diagnosed in 15 horses--11 fillies and 4 colts. Review of the medical records provided results of physical, microbiologic, radiographic, and endoscopic examinations, treatment protocols, complications, and recovery rate. All affected horses had visible swelling in the parotid gland region, 9 had abnormal respiratory noise, 5 had pneumonia, and 1 had dysphagia. Six horses were treated by median septum fenestration alone, and in 8 horses, this procedure was combined with resection of the mucosal flap at the pharyngeal orifice of the eustachian tube. One horse was not treated. Follow-up information was obtained for 13 horses. Rate of recurrence was 33% (2/6) after fenestration alone and was 29% (2/7) when both procedures were combined. One horse that had been treated using combined procedures died of pneumonia, and a horse treated unsuccessfully by septum fenestration was euthanatized because of persistent dysphagia. Eight horses greater than 2 years old when follow-up information was obtained were reported to be healthy, and 4 of these had raced successfully.

Animals↗
PubMed1989

Equine mastitis--a review of 28 cases.

Mastitis was diagnosed in 28 mares. Cytological evaluation of milk samples showed large numbers of neutrophils in 72 per cent and bacteria in 33 per cent. Aerobic bacteria were cultured from 71 per cent of samples. Streptococcus zooepidemicus was the most common isolate (37 per cent). Gram-negative species accounted for 42 per cent. Determination of the probability for antimicrobial susceptibility of bacterial isolates from mares with mastitis indicated that a trimethoprim-sulphonamide combination would be active against more than 75 per cent of isolates while penicillin would be active against less than 60 per cent. Systemic antibiotics, frequent milking, hotpacks and/or hydrotherapy and, if possible, infusion of an intramammary antibiotic preparation is recommended for treatment of equine mastitis.

Animals↗
PubMed1988

Serological survey for selected diseases in the endangered San Joaquin kit fox (Vulpes macrotis mutica).

Blood from endangered San Joaquin kit foxes (Vulpes macrotis mutica) inhabiting the Elk Hills Naval Petroleum Reserve, Kern County, and the Elkhorn Plain, San Luis Obispo County, California, was collected in 1981, 1982 and 1984 and sera were tested for antibodies against 10 selected pathogens. Proportions of kit fox sera containing antibodies against pathogens were: canine parvovirus, 100% in 1981-1982 and 67% in 1984; infectious canine hepatitis virus, 6% in 1981-1982 and 21% in 1984; canine distemper virus, none in 1981-1982 and 14% in 1984; Francisella tularensis, 8% in 1981-1982 and 31% in 1984; Brucella abortus, 8% in 1981-1982 and 3% in 1984; Brucella canis, 14% in 1981-1982 and none in 1984; Toxoplasma gondii, 6% in 1981-1982; Coccidioides immitis, 3% in 1981-1982; and Yersinia pestis and Leptospira interrogans serotypes canicola, grippotyphosa, hardjo, icterohaemorrhagiae, and pomona, none in 1981-1982. Although antibodies against selected pathogens were present, no clinical indications of disease were observed in these fox populations.

Animals↗
PubMed1987

Hematologic values of the endangered San Joaquin kit fox, Vulpes macrotis mutica.

Between 1981 and 1982 blood samples were collected from 64 adult San Joaquin kit foxes, Vulpes macrotis mutica, in western Kern County, California. The goal of the study was to establish normal blood values for this endangered species, and to determine whether changes in them could be used to assess the possible effects of petroleum developments on these foxes. None of the values differed significantly between the sexes, or between foxes sampled in developed habitats compared with foxes sampled in undisturbed habitats. Mean values of Hb, MCH, MCHC, and WBC counts differed significantly between summer and winter. Average hematological characteristics were: RBC, 8.4 X 10(6)/microliter; Hb, 14.5 g/dl (summer), 15.6 g/dl (winter); PCV, 46.9%; MCV, 56.3 fl; MCH, 17.8 pg (summer), 18.4 pg (winter); MCHC, 31.2 g/dl (summer), 33.2 g/dl (winter); and WBC, 6,200/microliter (summer), 7,500/microliter (winter). Comparisons of hematological data for kit foxes, coyotes (Canis latrans), and wolves (Canis lupus) confirmed a previously published observation that within mammalian families RBC counts are correlated inversely with body weight, and that MCV is correlated directly with body weight.

Animals↗