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Biomedical subjects

G D Potter

Publications and source records attributed to G D Potter.

At least 55 records · Page 3Linked to original sources
PubMed1983

Pedigree analysis of four decades of Quarter Horse breeding.

Pedigrees of randomly selected Quarter Horses born in each of the years 1946, 1956, 1966 and 1976 and of winning halter, cutting and race horses born in the same years were evaluated and compared. Average inbreeding and inter se relationship levels and relationships of influential ancestors to the sample were calculated for each sample. The amount of Thoroughbred influence and the average generation interval were also determined for each random sample. The levels of inbreeding found in the random samples were low, ranging from 1.3% in 1956 to 2.6% in 1966; however, these levels were higher than would be expected if mating were random. Show and race winners born in 1976 appeared to be less inbred than random horses of the breed. The estimated average inter se relationship within the random samples increased from 0% in 1946 to 3% in 1966, decreasing again to 0% in 1976. Horses in the elite samples appeared to be more closely related to each other than those in the random samples. Fifteen ancestors of horses in the random samples were identified as influential to the Quarter Horse breed. Many of these same ancestors were influential in the halter and cutting samples, but only one was influential in the race samples. The percentage of pedigree lines in the random samples that contained a Thoroughbred ancestor were as follows; 1946, 27.5%; 1956, 19.2%; 1966, 23.2% and 1976, 31.4%. The average generation interval fluctuated from approximately 8 yr to approximately 10 yr for the random samples.

Animals↗
PubMed1982

Induction of parturition in the mare with prostaglandin F2 alpha.

Thirty-one mares of Quarter Horse and Thoroughbred breeding were utilized in two experiments to evaluate the efficacy of prostaglandin F2 alpha (PGF2 alpha) for induction of equine parturition and to monitor the effects of this treatment on viability of the resulting foals. Three of five mares given 5 mg PGF2 alpha (im) on day 338 of gestation foaled 19.6+/-8.2 hr postinjection. In the second experiment immediately following 3 daily injections of 10 mg estradiol cypionate (ECP) given on days 326, 327 and 328 of gestation, seven mares were infused (iv) with PGF2 alpha at the rate of 1.3 mg/hr for 24 hr or until parturition occurred. Four of the seven mares foaled in 8.8+/-1.8 hr after the start of infusion. Side effects including sweating, hypothermia, increased respiration rate and diarrhea were evident in both injected and infused mares, but effects were transient. Neither the injection, nor infusion route of administration of PGF2 alpha adversely affected the viability of foals. However, some mares induced to foal 12 days prior to expected parturition had foals with slightly weaker pasterns than those of control mares.

Animals↗
PubMed1982

Glucose absorption by in vitro perfused ileum of the fetal rat.

In vitro intraluminal perfusion of the fetal rat ileum at 19 and 20 days of gestation was employed to measure the rate of glucose absorption and the unidirectional fluxes of 3-O-methylglucose (3-O-MG). Fetal ileum was mounted on pipettes within an oxygenated bath and perfused with a solution containing glucose or 3-O-MG and polyethylene glycol with average molecular weight of 4,000 (PEG) as a marker substance. We verified that the PEG was not transported and did not diffuse across the fetal ileum. Scanning and electron microscopy before and after perfusion demonstrated preservation of mucosal anatomy. The rate of glucose absorption was 200 +/- 17 mumol.h-1.g-1 at 19 days and increased significantly to 378 +/- 12 mumol.h-1.g-1 at 20 days. The absence of sodium abolished this process. The flux of 3-O-MG from lumen to bath was 88 +/- 10 mumol.h-1.g-1 at 19 days and 160 +/- 16 mumol.h-1.g-1 at 20 days. Bath-to-lumen flux was -17 +/- 2 mumol.h-1.g-1 and did not vary with age. Active, rapidly developing transport of glucose and 3-O-MG is demonstrated by in vitro luminal perfusion of the fetal rat ileum at 19 days.

3-O-Methylglucose↗
PubMed1982

Milk production of quarter horse mares during 150 days of lactation.

Milk production was measured in fourteen Quarter Horse mares at seven stages of a 150-d lactation period. Mares were divided into two groups of seven and fed diets containing either soybean meal or soybean meal and urea as nitrogen supplements. Rations were isocaloric, contained approximately 12.5% crude protein and were fortified with vitamins and minerals. Daily milk yield was estimated by the weigh-suckle-weigh method and milk composition was determined from samples taken by hand milking. Average daily milk yield ranged from 11.8 kg in early lactation to 9.8 kg in late lactation. Differences (P less than .01) in milk yield due to number of previous lactations were observed. Also, diet influenced (P less than .01) milk yield, with mares fed soybean meal producing an average of 1.2 kg more milk/d than mares fed urea as part of the N supplement. Further, stage (day) of lactation influenced (P less than .01) daily milk yield. The largest mean daily milk yield was measured at approximately 30 d postpartum, but the predicted lactation curve was linear (P less than .05) over the range of observations in this study. Average percentages of total solids, protein and fat over the 150-d lactation were 10.5, 2.1, and 1.3, respectively. All components decreased significantly with advancing lactation. There was a trend toward a positive association between milk yield and solids content of the milk, but it was not significant. Milk yield was not significantly related to fat content of the milk. However, milk yield and protein content were correlated (r = .23; p less than .05). As expected, solids content of the milk was positively associated with percentages of protein (r = .59; P less than .01) and fat (r = .44; P less than .01). Relationships among milk components were similar after adjustment for days in milk. However, yield of milk and composition were unassociated (P less than .05) when days in milk were held constant.

Animals↗
PubMed1982

Breath methane excretion in patients with unresected colorectal cancer.

The objective of our study was to verify or refute the observation that patients with unresected colorectal cancer are more likely to be breath methane excretors than the general population. Intracolonic heme had no effect on breath methane excretion of 11 normal volunteers given oral hemoglobin. Laxative-enema colonoscopy preparation had a profound effect on the subsequent measurement of breath methane. Three of 4 volunteer methane excretors became nonexcretors, and 2 remained nonexcretors for 21 days and 7 months, respectively. No significant difference was found in the frequency and the amount of breath methane excretion in 55 patients with unresected colorectal cancer and in 99 control subjects. However, 13 patients with unresected descending or sigmoid colon cancers were almost twice as likely to be breath methane excretors as 38 patients with colorectal cancer at other sites.

Adult↗
PubMed1982

Influence of photoperiod on the pregnant and postpartum mare.

Over a 2-year period, mares (n = 32) of predominantly Quarter Horse breeding and their foals were used to study the effects of photoperiod on reproduction during the periparturient period. Specific objectives of the study were (i) to evaluate the effects of an extended photoperiod regimen (16 hours' light) on gestation length, foal development, and postpartum reproductive performance, and (ii) to measure changes in plasma progesterone concentrations during the last trimester of gestation and plasma luteinizing hormone (LH) concentrations after foaling until ovulation. Mares in the extended daylength treatment group had shorter (10 days) mean gestation length (P less than 0.01) than did control mares (exposed to normal daylight hours). Although foals of mares exposed to long photoperiod were carried for a shorter term, their birth weights tended to be heavier, but not significantly, than those of foals from control mares. Foal size, as determined by body measurements, was not affected by the photoperiod. Neither interval from parturition to 1st ovulation nor onset of estrus to ovulation were significantly affected by the extended photoperiod. Plasma progestogen concentrations increased from basal levels at prepartum weeks 4 and 5 to peak values a week before foaling in both mare groups. The LH profiles from parturition to ovulation were similar for both mare groups. However, mean plasma LH values during the 7 days before the 1st ovulation were higher (P less than 0.05) in mares exposed to extended daylength than in control mares.

Animals↗
PubMed1981

Effects of lead on benzene metabolism.

The possibility that Pb could affect benzene metabolism, through inhibition of enzyme synthesis, was examined by studies of the effects of chronic oral Pb treatments on benzene conversion to phenol. Rats were given either distilled deionized water or 0.05, 0.58, 17, or 352 ppm Pb solutions as drinking water. After 6, 9, 12, and 15 wk of treatment, rats from each group were sacrificed and in vitro benzene metabolism by benzene hydroxylase was measured in liver enzyme preparations. After 24 wk, the remaining animals were injected ip with 400 mg/kg benzene and urinary phenol levels measured daily for 4 d. The enzyme activity, studied in vitro, was significantly increased in animals that ingested the 352 ppm solution for 6 wk. Also, Pb levels in all groups of animals were significantly higher in tissues from the animals that ingested 352 ppm Pb. Although urinary phenol levels accounted for 30-40% of the ip benzene dose, Pb ingestion had no significant effect on phenol excretion. These results suggested that oral Pb treatments had a significant effect on the enzyme responsible for benzene hydroxylation to phenol. However, other unknown factors appear to compensate for these changes in vivo.

Animals↗
PubMed1979

Fertility of donor mares following nonsurgical collection of embryos.

Embryos were collected nonsurgically on Day 7 or 8 after ovulation from 7 Quarter horse mares using a modified 30-ml Foley catheter to flush the uterine horn ipsilateral to the recent ovulation with 500 ml TCM-199 containing Hepes buffer. After collection, the uteri were infused with nitrofurazone to reduce the chances of infection due to the procedure. Eleven collections from 7 mares resulted in recovery of 9 embryos and nonsurgical transfer of 4 of these resulted in the birth of one foal. After collections, 8 oestrous cycles averages 22.75 days and 2 extended oestrous cycles were 43 and 59 days long respectively. Of 6 mares mated after one or two embryo collections, 5 conceived to a single service and the sixth during the third oestrus in which she was covered.

Animals↗
PubMed1975

Critical review of tomography in radiology and nuclear medicine.

This review covers conventional radiographic tomography, radioisotopic tomography, and a review of computerized transaxial tomography. Simple, reproducible radiographic tomographic methods are increasing in use, and despite their complexity, the diagnostic results are superior to conventional radiographs. There are many different motions of the X-ray tube and the film which can be employed to create a tomogram. The perfect tomographic motion is partly determined by the geometric shape of the object to be imaged and the thickness of the plane of interest. The undirectional tomographic method blurs a point in a linear fashion; the pleuridirectional method blurs a point over a wider surface. Among the most popular directions used are linear, circular, elliptical, and hypocycloidal. The numerous applications of tomography described in this review are an encouraging, broad-based foundation from which the most clinically useful and economically feasible devices will emerge.

Adrenal Gland Neoplasms↗
PubMed1973

The hard palate.

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Adult↗