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Biomedical subjects

W R Allen

Publications and source records attributed to W R Allen.

At least 163 records · Page 9Linked to original sources
PubMed1982

Maternal anti-fetal cytotoxic antibody responses of equids during pregnancy.

The maternal immunological response to the developing equine fetus was investigated in 69 pregnancies of various genotypes. In normal intraspecies horse pregnancy (N = 16), 94% of mares produced strong cytotoxic antibody responses to paternal histocompatibility antigens which were first detectable between 44 and 70 days after ovulation. In all other types of pregnancy examined (intraspecies donkey, N = 19; interspecies mule, N = 6; interspecies hinny, N = 2; extraspecies horse-in-donkey, N = 3; and extraspecies donkey-in-horse, N = 21), antibody production was observed less frequently, and sometimes with a more irregular onset. However, the dominant pattern of response was similar to that observed in intraspecies horse pregnancy. Although the development of cytotoxic antibody correlated well with the formation of the equine endometrial cups, histological and serological evidence demonstrated that the accumulation of lymphocytes which occurs around the endometrial cups in intra- and interspecies pregnancies, and in the endometrial stroma in contact with trophoblast in extraspecies donkey-in-horse pregnancies which lack endometrial cups, can occur in the absence of a detectable cytotoxic antibody response. The cytotoxic antibody produced by mares carrying extraspecies donkey conceptuses appeared to be directed primarily against donkey alloantigens, and not species-specific antigens, emphasizing the importance of maternal recognition of paternally derived fetal histocompatibility antigens during equine pregnancy.

Animals↗
PubMed1982

Use of ultrasound echography for early diagnosis of single and twin pregnancy in the mare.

In 1981 a trial was conducted on 6 Newmarket Thoroughbred stud farms into the use of real-time ultrasound echography (scanning) as an aid to the early diagnosis of pregnancy in the mare. The procedure was found to be practicable and interpretation of the findings was relatively straightforward. Pregnancy was positively diagnosed from as early as 14 days after ovulation and a number of twin pregnancies were recognized, some in which the conceptuses were situated in separate horns of the uterus but an almost equal number in which the conceptuses were together in the same horn. It was concluded that the technique of scanning will become an established part of stud-farm practice because it enables early identification of non-pregnancy and also of twin pregnancy before the critical stage of endometrial cup formation.

Animals↗
PubMed1982

A comparison of agents for inducing parturition in mares in the pre-viable and premature periods of gestation.

Various regimens of prostaglandins, alone or followed by oxytocin, were given to induce parturition in mares during the pre-viable and premature periods of gestation and in near-term mares. The most successful method of induction was found to be 2 i.m. injections of 500 micrograms fluprostenol (Equimate: I.C.I.) at a 2-h interval followed (if necessary) by 10-20 i.u. oxytocin injected i.v. in 5 i.u. serial increments every 15-20 min. Peak concentrations of the prostaglandin metabolite (PGFM) in response to the inducing agents were shown to be associated with delivery at, but not before, 320 days of gestation. A radiolabelled study of [14C]fluprostenol distribution showed that fluprostenol was present in placenta, amnion, allantoic and amniotic fluid, and in foal plasma and liver.

Animals↗
PubMed1981

Insulin and growth factors stimulate rapid posttranslational changes in glucose transport in ovarian granulosa cells.

The glucose analogues, 3-O-methyl-D-glucose and 2-deoxy-D-glucose, have been used to characterize glucose transport and its regulation by serum and growth factors in monolayer cultures of granulosa cells obtained from bovine ovaries. Uptake of 3-O-methylglucose was shown to be independent of the Na+-gradient, independent of energy, did not show accelerated exchange, and was stereospecific. Serum withdrawal resulted in a biphasic decrease in initial rates of glucose uptake with half-times for the two phases of 50 minutes and 3 hours. Insulin could prevent the decrease in uptake rates with a half-maximum concentration of 10.0 1/8 3 nM. Insulin was shown to stimulate DNA synthesis with a concentration of half-maximum response of 28 nM. Insulin or serum stimulation of 3-O-methylglucose uptakes in serum-starved cells resulted in a two threefold increase in initial rates, with a time for half-maximum stimulation of 3 minutes. The insulin-stimulated increase was insensitive to cycloheximide and cyanide during the first 30 minutes, and this early, rapid stimulation was also produced by brain FGF (fibroblast growth factor), pituitary FGF, epidermal growth factor, calf serum, and some but not all samples of follicular fluid. Insulin also stimulated 2-deoxyglucose and a-aminoisobutyric acid uptake during the first 5 minutes of addition and these early stimulations were shown to be posttranslational changes.

Animals↗
PubMed1981

Biological functions and receptor binding activities of equine chorionic gonadotrophins.

The role of equine chorionic gonadotrophin (CG, formerly termed Pregnant Mare serum Gonadotrophin, PMSG) in maintaining equine pregnancy was investigated by examining the effects of this hormone on the maternal ovaries during early gestation and relating these findings to the receptor binding activities of CG in vitro. Measurement of plasma progestagen profiles in mares and donkeys carrying horse, donkey, mule ( female horse X male donkey) and hinny (female donkey X male horse) conceptuses confirmed that CG induced several secondary ovulations and thus maintained maternal progestagen concentrations. However, in mares carrying horse and mule conceptuses and in donkeys carrying donkey conceptuses the growth of the follicles that gave rise to the secondary corpora lutea occurred before CG was secreted and the CG did not express any FSH-like activity. Nevertheless, in donkeys carrying hinny pregnancies the CG secreted by the hinny conceptus stimulated massive follicular growth in addition to luteinization, presumably because of an enhanced sensitivity of donkey ovaries to hinny CG which, as demonstrated in previous studies, is a mixture of horse and donkey CG and hence has considerably more FSH-like activity than normal donkey CG. In-vitro receptor binding experiments showed that both horse and donkey gonadal tissues possessed a low binding affinity for horse CG compared to that exhibited by equivalent gonadal tissues of other species. Furthermore, horse CG bound with low, but significant, affinity to horse and donkey LH receptors and donkey FSH receptors, but exhibited negligible binding to horse FSH receptors. We suggest that in equids the receptor-mediated refractoriness to the gonadotrophic activities of the intraspecific chorionic gonadotrophin protects the ovaries during pregnancy.

Animals↗
PubMed1980

Studies on fenbendazole for treating lung and intestinal parasites in horses and donkeys.

The efficacy of orally administered fenbendazole on lung and intestinal parasitism in equids was investigated in a mixed herd of pony mares, jenny donkeys and foals. A single dose of 7.5 mg fenbendazole/kg body weight effectively removed intestinal parasites from the ponies, donkeys and foals, but higher doses and repeated treatments failed to eliminate lungworm infections in donkeys. The finding of eosinophilia proved useful in detecting lungworm infections in donkeys.

Animals↗
PubMed1980

Preliminary studies on the use of an oral progestogen to induce oestrus and ovulation in seasonally anoestrous Thoroughbred mares.

Daily oral administration of 30 mg allyl trenbolone (Regumate) for 10 to 15 days to 61 barren, maiden and lactating Thoroughbred mares which were exhibiting either deep anoestrus, shallow anoestrus, prolonged spring oestrus or lactation anoestrus, resulted in 54 mares (88 per cent) showing oestrous behaviour within 8 days, and 51 mares (84 per cent) ovulating within 18 days, after the last dose of compound. Response rate was lowest in mares in deep anoestrus. Of the 38 Regumate-treated mares which were covered during the induced oestrus, 21 (55 per cent) conceived. The practical value of this form of progesterone withdrawal therapy as a method for hastening the onset of the breeding season in Thoroughbred mares is discussed.

Anestrus↗
PubMed1980

Purification and characterization of the gonadotropin secreted by cultured horse trophoblast cells.

Equine chorionic gonadotropin (eCG) secreted by horse trophoblast cells cultivated in vitro was isolated and its chemical, immunochemical, and biological characteristics were compared to those of the gonadotropin secreted in vivo and isolated from PMS. It was also compared with eCG isolated from the tissue of origin, the endometrial cups. The gonadotropin secreted in vitro had a smaller molecular size, contained appreciably less carbohydrate, and showed different amino-terminal residues from that secreted in vivo. In addition, there were significant differences in amino acid composition between eCG secreted in vivo and that secreted in vitro. The reactivity of eCG (isolated from the medium of cultured trophoblast cells) in homologous eCG (isolated from PMS) and equine LH and FSH RIAs suggested close antigenic similarities to eCG isolated from PMS. However, compared to serum-derived eCG, eCG secreted in vitro showed reduced activity in both LH (13%) and FSH (9-24%) bioassays and in LH and FSH radioreceptor assays (40-50%). The differences in bioassay potencies may be accounted for in part by the lower sialic acid content of the gonadotropin secreted in vitro. With respect to both bioactivity and chemical composition, the eCG secreted in vitro more closely resembled the eCG isolated from endometrial cups than that isolated from serum.

Amino Acids↗
PubMed1980

Purification and characterization of donkey chorionic gonadotrophin.

Serum of the pregnant donkey, like that of the mare, contains a gonadotrophin of chorionic origin. The chorionic gonaditrophin of the donkey (dCG) has been isolated in purified form from the serum of pregnant donkeys using methodology previously employed for the purification of pregnant mare chorionic gonadotrophin (eCG). Unlike eCG, dCG is predominatly an LH in biological tests. In the in-vitro rat Leydig cell assay, dCG was as active as eCG, but in the in-vitro rat seminiferous tubule assay for FSH and in the augmentation assay, dCG was considerably less potent than eCG (1-10%). Specific rat testis radioreceptor assays for LH and FSH also showed dCG to be at least nine times more potent in LH than in FSH activity. Chemically, dCG was found to be similar to eCG in fractionation behaviour and glycoprotein nature. However, dCG had significantly less carbohydrate (31%) than had eCG (45%) and several differences were noted in a comparison of amino-acid compositions. A single amino-terminal residue, phenylalanine, was detected in dCG. Immunologically, dCG cross-reacted in homologous radio-immunoassays for eCG, equine LH and equine FSH, but its inhibition curves were all nonparallel with those of the respective equine gonadotrophin standards.

Amino Acids↗
PubMed1980

Racial and sex differences in "images of the future".

Scenarios of future careers were written by 454 senior high school students in a southeastern high school. Random samples of 40 black females, 40 black males, 40 white males, and 40 white females were scored for eight characteristics and means were compared through analysis of variance. Only one sex difference was found, girls rated higher than boys on perception of self as changed in the future. The blacks projected greater career satisfaction for the future but the whites wrote longer scenarios and projected greater perceptions of changes in the world/mankind, greater awareness of future problems, more proposals of solutions to future problems, and stronger perceptions of self as a creative problem solver. There were no differences in commitments to making a better world or solving future problems.

Adolescent↗
PubMed1979

The irritancy of chlorhexidine gluconate in the genital tract of the mare.

Uterine irrigation was carried out in eight Welsh pony mares using 50 ml of chlorhexidine gluconate solution diluted to give active ingredient concentrations of 0.25 per cent to 2 per cent. Treatment was repeated up to twice in mares showing no adverse effects and irritancy of treatment judged on clinical symptoms and uterine biopsy. Results indicated the inadvisability of using a higher concentration than 0.25 per cent. Three daily applications of a diluted surgical scub solution containing 2 per cent chlorhexidine gluconate to the penis of an arab stallion failed to produce symptoms or irritation. An in vitro minimum inhibitory concentration test performed with the contagious equine metritis organism confirmed its high sensitivity to both chlorhexidine gluconate preparations.

Animals↗