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Biomedical subjects

G B Whitehurst

Publications and source records attributed to G B Whitehurst.

8 recordsLinked to original sources
PubMed1991

Effect of indomethacin, epinephrine, prostaglandin E2 and insulin on lipolysis in bovine adipose tissue in vitro.

1. Fasting of ad libitum- or maintenance-fed steers for 4 to 9 days did not alter basal lipolytic rates in vitro. 2. Epinephrine stimulation of adipose tissue of fasted steers resulted in greater (P less than 0.05) lipolysis than in tissue from fed steers. 3. Prostaglandin E2 (PGE2) did not alter epinephrine-stimulated lipolysis in ad libitum- or maintenance-fed cattle. 4. Indomethacin did not influence basal lipolysis, even in the presence of PGE2. 5. Insulin neither affected basal lipolysis nor inhibited dibutyl cAMP-stimulated lipolysis.

Adenylyl Cyclases↗
PubMed1986

Evaluation of prostaglandin E2 as a regulator of lipolysis in bovine adipose tissue.

Effects of exogenous prostaglandin E2 (PGE2) on rates of lipolysis in sections of subcutaneous adipose tissue biopsied from fed and fasted Holstein steers were determined. The interaction of PGE2 with several exogenous effectors of lipolysis and of the adenylate cyclase-cAMP system also was measured. Epinephrine increased basal (nonstimulated) lipolysis approximately one-fold. Prostaglandin E2 had no effect on either basal or epinephrine-stimulated lipolysis. Dibutyryl cAMP increased rate of lipolysis .4-fold, whereas theophylline increased lipolysis more than one-fold. Theophylline had an additive effect on epinephrine-stimulated lipolysis. Dibutyryl cAMP increased theophylline-stimulated lipolysis but not epinephrine-stimulated lipolysis. Prostaglandin E2 had no effect on epinephrine-, dibutyryl cAMP- or theophylline-stimulated lipolysis. Fasting decreased basal lipolysis by 40%. Furthermore, lipolysis in tissue incubated with PGE2, epinephrine or PGE2 plus epinephrine decreased from 30 to 50% upon fasting. As also shown with tissue from fed steers, PGE2 did not alter basal or epinephrine-stimulated lipolysis in tissue from fasted steers. Influences of exogenous effectors on lipolysis in adipose tissue from fed and fasted steers indicate that PGE2 does not control the adenylate cyclase-cAMP system that regulates lipolysis in bovine adipose tissue.

Adipose Tissue↗
PubMed1985

Adipose tissue growth and cellularity: changes in bovine adipocyte size and number.

Forty crossbred steers of similar birth date and fed the same growing-finishing diet were used to study adipocyte changes in six fat depots during growth from 11 to 19 mo of age. Steers were slaughtered at 2-mo intervals. Adipose tissue samples were obtained from kidney, mesenteric and brisket fat and subcutaneous, intermuscular and intramuscular fat from the 10th to 12th rib section. The osmium tetroxide fixation technique was used for determination of cell size and number. Except for three brisket fat samples, distributions of adipocyte diameters from six different fat depots were monophasic during the age range considered in this study. At 17 mo of age, the mean adipocyte diameter, in decreasing order, was: kidney fat greater than mesenteric greater than subcutaneous greater than intermuscular greater than intramuscular greater than brisket fat. Fat deposition during growth to 19 mo of age occurred mainly by hypertrophy of adipocytes. An apparent cell hyperplasia occurred in the intramuscular fat depot from 11 to 15 mo and in the brisket fat depot after 15 mo of age. Based on cellularity characteristics, evidence exists to classify intramuscular and brisket fat depots as late-developing ones. Cell number/gram of intramuscular adipose tissue was a better predictor of marbling score than was fat cell diameter.

Adipose Tissue↗
PubMed1983

Acid phosphatase in prostatic tissue homogenates from patients with benign prostatic hyperplasia and prostatic carcinoma.

Acid phosphatase activity biochemically in the primary tumor of 20 patients with prostatic carcinoma, was studied in an attempt to understand the basis for a correlation or lack of correlation between serum and/or bone marrow acid phosphatase levels and the presence and/or clinical behavior of prostatic carcinoma. The enzyme activity was similarly measured in 19 patients with benign prostatic hyperplasia as controls. On the average, enzyme activities were lower (P less than 0.002) in the tissues from patients with carcinoma. There was no correlation of enzyme activity in tumor with the age of the patient, stage of disease, degree of differentiation of the tumor, or serum acid phosphatase activity.

Acid Phosphatase↗
PubMed1982

Prostatic hexosaminidase activity in patients with benign prostatic hyperplasia and prostatic carcinoma.

Hexosaminidase activity in prostatic tissue has been compared in 15 patients with benign prostatic hyperplasia and 15 patients with prostatic carcinoma. The ratio of enzymatic activity for the two substrates tested (p-nitrophenyl-2-acetamido-2-deoxy-beta-D-glucopyranoside and p-nitrophenyl-2-acetamido-2-deoxy-beta-D-galactopyranoside) was not significantly different in the two groups of patients. The proportion of hexosaminidase represented by the B isozyme was not significantly different for the two groups of patients. Prostatic tissue hexosaminidase was greater (p = 0.0141) in carcinomatous prostates than in hyperplastic prostates.

Acetylglucosaminidase↗
PubMed1982

Decrease in creatine kinase in human prostatic carcinoma compared to benign prostatic hyperplasia.

Many previous studies have shown that a proportion of patients with carcinoma of the prostate have increased activity of the creatine kinase (E.C. 2.7.3.2) isoenzyme designated BB in sera from their peripheral blood. We have analyzed tissues from prostatic hyperplasia of 22 patients and from prostatic carcinoma of 23 additional patients. Prostatic carcinomas contain less (p less than 0.001) creatine kinase activity (units/g) than do prostates with benign prostatic hyperplasia. The facts that (a) histochemical studies that we performed confirmed the observation reported previously by others that creatine kinase activity is found primarily in the epithelial elements of hyperplastic prostates and prostatic carcinomas, (b) the carcinomas that we examined had, on the average, a somewhat larger epithelial component than the hyperplastic prostates that we examined, and (c) prostate cancer was found to contain less creatine kinase activity than hyperplastic prostates suggest that the epithelial cells in prostate cancers contain less creatine kinase activity per cell than do those from hyperplastic prostates. The BB form of creatine kinase accounts for 98% of the activity in prostatic carcinoma and in prostates without cancer. Creatine kinase has been discussed as a possible marker for prostatic carcinoma, and we had hoped that it might be useful for the assay of tumor burden. Our data suggest that, if creatine kinase is to be useful in the monitoring of tumor burden, it will be useful only in the contexts of particular patients studied longitudinally since the creatine kinase activity varies enormously among different prostatic carcinomas.

Aged↗
PubMed1978

Lactate as a precursor of fatty acids in bovine adipose tissue.

In vitro experiments were conducted to determine the rates of lactate, acetate, and glucose conversions to glycerol, CO2, and fatty acids by subcutaneous adipose tissue of cattle. To study the pathway for lactate utilization as a carbon source for lipogenesis, the effect of each of four substates (lactate, acetate, pyruvate, and glucose) on the rate of conversion of the other three was determined. The rates of lactate conversion to fatty acids and to glycerol were greater than those for acetate and glucose. Acetate, however, was oxidized to CO2 at greater rates than either lactate or glucose. Acetate was used for fatty acid synthesis at greater rates than pyruvate was less than that from lactate but greater than that from glucose. Acetate additions to the incubation media decreased the synthetic rates from lactate, pyruvate, and glucose. Pyruvate decreased rates of fatty acid synthesis from glucose but slightly (not statistically significant) stimulated synthesis from lactate and acetate. Lactate decreased glucose and pyruvate utilization but had no effect upon that of acetate. Our results clearly demonstrated that lactate can be used for fatty acid synthesis as well as for glycerogenesis by bovine adipose tissue.

Acetates↗