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Biomedical subjects

B L Lasley

Publications and source records attributed to B L Lasley.

At least 145 records · Page 8Linked to original sources
PubMed1983

Oestrogen secretion by in-vitro perfused testes: species comparison and factors affecting short-term secretion.

Testes from mature rats, rabbits, hamsters, guinea-pigs and dogs were perfused in vitro with added gonadotrophins to study the qualitative and quantitative aspects of oestrogen secretion by these species. After separation by high performance liquid chromatography (HPLC), the major oestrogen secreted by the testes of all five species was oestradiol-17 beta; lesser amounts of oestrone were also detected for all species. Secretion rates of oestradiol and testosterone were determined for one testis from each of six animals of each species after purification by HPLC. Oestradiol and testosterone secretion varied (P less than 0.05) among species on both per testis and per gram of testis bases. The rabbit, which was a high secretor of oestradiol, was used in subsequent experiments to study the factors which affect short-term oestradiol secretion by perfused testes. Luteinizing hormone (NIAMDD-LH-S21) at 100 ng/ml significantly stimulated oestradiol secretion by 2.9-fold and increased testosterone secretion by 155-fold. Follicle-stimulating hormone (NIH-FSH-S11) had no significant effect on secretion of either steroid. In a time-course study in which LH stimulation was started after 45 min of control perfusion, the rates of increase in oestradiol and testosterone secretion over time were similar. Increasing amounts of testosterone added directly to the arterial perfusion medium (0-10 micrograms/ml) resulted in an increase in oestradiol secretion in the absence of gonadotrophins. Oestradiol secretion increased in a dose-dependent manner up to 1.0 microgram testosterone/ml; there was no further stimulation of oestradiol secretion at 10 micrograms testosterone/ml. When testes were perfused with saturating concentrations of testosterone (10 micrograms/ml) neither LH nor FSH at 100 ng/ml increased oestradiol secretion above control values. It appears that the major factor affecting oestradiol secretion by in-vitro perfused rabbit testes is the amount of substrate (testosterone) available for aromatization.

Animals↗
PubMed1982

Comparison of in-vitro bioactivity and immunoreactivity of serum LH in normal cyclic and hypogonadal women treated with low doses of LH-RH.

The in-vitro test of rat interstitial cell testosterone secretion and a radioimmunoassay (RIA) were used to explore the nature of the LH released in women in response to LH-RH. The ratio of in-vitro bioactivity to immunoreactivity (B:I) calculated for serum samples collected from hypogonadal women using the standard LER-907 for comparison was 13.25 +/- 0.56. This mean ratio was significantly elevated (P less than 0.02) above that found for normal cyclic women, 9.48 +/- 0.49. After one i.v. injection of 10 micrograms LH-RH, 5 hypogonadal and 6 luteal-phase women showed an initial significant drop in the B:I ratio (P less than 0.05 and P less than 0.02 respectively) followed by a steady significant rise (P less than 0.03; P less than 0.01 respectively). This drop in the B:I ratio as immunoreactive LH rose and the rise in the B:I ratio as immunoreactive LH fell may be the result of the release of two or more kinds of LH, one or more with a slower in-vivo clearance rate and an increased B:I ratio.

Female↗
PubMed1982

Fetal-maternal gradients of steroid hormones in the nine-banded armadillo (Dasypus novemcinctus).

Gonadal and adrenal steroid hormone levels in plasma were measured in pregnant, non-pregnant and fetal armadillos. Progesterone demonstrated the largest placental gradient with levels 6 to 10-fold higher in the fetus. Testosterone levels were higher in male and lower in female fetuses, when compared to the respective maternal serum values. Dehydroepiandrosterone, and cortisol were consistently high in maternal as compared to matched fetal serum samples whereas the reverse was true for androstenedione. Tissue incubations with labelled pregnenolone indicated the major source of progesterone production to be the fetal adrenal whereas the fetal testes demonstrated a major conversion product consistent with dehydroepiandrosterone.

Animal Population Groups↗
PubMed1982

In vivo effects of delta 1-testololactone on peripheral aromatization.

To evaluate the in vivo effect of delta 1-testololactone on peripheral aromatization, studies were performed on seven postmenopausal women with metastatic breast cancer. Analysis of variance indicated that there were significant increases of circulating androstenedione (p less than 0.05) and estradiol (p less than 0.001) during administration of different doses of testololactone. Androstenedione levels were increased with all doses of testololactone tested (50, 100, 250, and 500 mg every 6 hr for 14 days each), while estradiol rose with only the 250- and 500-mg dosages. With administration, there was a significant decrease of estrone (p less than 0.001) with the mean level falling from 26 +/- 3 (S.E.) to 11 +/- 2 pg/ml. The addition of adrenal suppression (dexamethasone, 1 mg nightly at 11 p.m.) significantly lowered androstenedione (p less than 0.05) but had no effect on estrone or estradiol levels. Long-term therapy (up to 6 months) with the 250-mg dosage showed continual suppression of estrone with no escape being observed. Studies to determine the reason for the increase of estradiol with testololactone suggested cross-reactivity of the antibody with in vivo metabolites of the drug. However, these possible metabolites did not bind to uterine cytosol estrogen receptors. The decrease in estrone with testololactone administration presumably explains its antitumor properties.

Aged↗
PubMed1981

Pregnancy monitoring in diverse primate species by estrogen and bioactive luteinizing hormone determinations in small volumes of urine.

Immunoreactive estrogen and luteinizing hormone/chorionic gonadotropin (LH/CG) bioactivity have been measured throughout pregnancy in diverse primate species with a sample methodological approach utilizing small volumes of urine collected randomly. Total immunoreactive estrogen levels and the relative abundance of component estrogens (estrone, estradiol and estriol) at various stages of gestation were compared in the human, orangutan, pygmy chimpanzee, Douc langur and capuchin. Measurement of urinary LH/CG bioactivity enables an earlier detection of pregnancy when compared to the nonhuman primate pregnancy test. The methods described provide a practical and non-stressful way to detect and monitor pregnancy in widely divergent primate species.

Animals↗
PubMed1981

Comparison of urinary oestrogen excretion in South American primates.

Changes in the excretion of immunoreactive oestrogens and biologically active LH were assessed from measurements on small samples of urine collected from a capuchin, a tamarin, a spider monkey and a squirrel monkey. The hormone profiles were used to time matings of the capuchin and spider monkey; conception and pregnancy ensued. Detailed analysis of one urine sample from each female by using partition chromatography and reverse-phase high-pressure liquid chromatography showed that oestrone was more abundant than oestradiol-17 beta and oestriol combined, but the relative contribution of individual oestrogens to the total oestrogen complement differed. In the sample from the capuchin, an immunoreactive oestrogen slightly less polar than oestradiol appeared to be the most abundant urinary oestrogen.

Animals↗
PubMed1981

Estrogen excretory patterns in the Indian rhinoceros (Rhinoceros unicornis), determined by simplified urinary analysis.

Daily urine samples obtained at random from 3 mature Indian rhinoceroses (Rhinoceros unicornis) were evaluated for immunologic estrogen concentration and were indexed by creatinine (Cr) concentration. Chromatographic separation and enzyme hydrolysis of the estrogenic components indicated that the major urinary estrogen in this species is immunoreactive estrone (greater than 95%). Cyclic variations of immunoreactive estrogens (basal values of 0.1 to 0.3 microgram/mg of Cr. peak values of 5.8 to 12.5 microgram/mg of Cr) were observed at an interval of 43 +/- 2 days (4 cycles) which appear to reflect the apparent ovarian cycles. The method presented offers a practical approach for the monitoring of ovarian events in large, nontractable species.

Animals↗
PubMed1981

Monitoring the estrous cycle of the Asian elephant (Elephas maximus), using urinary estrogens.

The estrous cycle of the Asian elephant (Elephas maximus) was monitored by analysis of urinary estrogens. Daily morning urine samples were analyzed for estrone (E1), estradiol (E2), and total immunoreactive estrogen (ET). The ET values were shown to correlate poorly with E1 and E2 values and failed to reveal any patterns of reproductive cycling. Daily E1 and E2 values, indexed by creatinine concentrations, demonstrated cyclic profiles in those samples of sufficient concentration. The technique offered a simple, noninvasive method of documenting ovarian function in the elephant.

Animals↗
PubMed1980

Annual circulating testosterone levels in captive and free-ranging male armadillos (Dasypus novemcincuts).

Mean circulating concentrations and seasonal changes in plasma testosterone over 3 years were similar in free-ranging and captive male armadillos. The highest concentrations were seen in the summer months, i.e. at the time of maximum breeding, but the relatiely high values at other times and the inability of ACTH to restore dexamethasone-suppressed testosterone concentrations confirms that testicular function continues throughout the year. There was a gradual rise in plasma testosterone to adult levels from the 5th to the 9th month of life in captive-born males, indicating that sexual maturity is reached within the first year of life and that captivity is not deleterious to Leydig cell function.

Adrenal Glands↗
PubMed1980

Monitoring the female reproductive cycle of great apes and other primate species by determination of oestrogen and LH in small volumes of urine.

A practical approach for monitoring the reproductive cycle of primates is described. Ovulation, implantation, gestation and post-partum amenorrhoea were identified from measurements of total immunoreactive oestrogen and LH bioactivity in incomplete daily urine samples collected from various species, including a gorilla, a chimpanzee and an orang-utan. Oestrogen values were determined by radioimmunoassay of hydrolysed urine using a non-specific oestriol antiserum and LH was assessed by measuring testosterone output from dispersed rat Leydig cells. Both hormone measurements were indexed by urinary creatinine levels to help adjust for differences in urine concentration and volume.

Animals↗
PubMed1979

Estrogen and luteinizing hormone secretion in diverse primate species from simplified urinary analysis.

A practical approach for monitoring urinary estrogen and luteinizing hormone (LH) in various primate species is described. Total immunoreactive estrogen (Et) levels, measured without chromatography, provided a convenient estimation of estrone, estradiol and estriol as the sum of their separated parts. Bioactive LH in urine was measured by the rat interstitial cell testosterone (RICT) in vitro bioassay. Correction for urinary creatinine content allowed for the comparison of hormone production from small volumes of urine collected from single daily voidings. Using these methods, urinary Et and LH profiles through the reproductive cycles of a human, gorilla, chimpanzee and capuchin monkey have been determined.

Animals↗
PubMed1979

The functional relationship between priming and releasing actions of luteinizing hormone-releasing hormone.

To examine the relationship between the priming and releasing actions of LRF on LH secretion, 14 normal cycling women received 4 different rates of LRF infusion (0.005, 0.01, 0.05, and 0.1 microgram/m2.min for 4 h). The releasing action of the infusion was measured as the area under the curve and the priming effect was assessed by the acute LH increment in response to a test pulse of LRF (10 microgram) at the end of infusion. At the lower 2 infusion rates, there were only minor changes in releasing function, but it increased exponentially (r = 0.986) with higher rates of infusion. In contrast, the priming effect of the lower 2 doses of infusion increased markedly as a function of infusion rate, but no additional priming was found with the higher rates of infusion. Thus, over the range of infusion rates employed, the releasing and priming functions of LRF appear to be dose dependent. These results indicate that the interdependent releasing and priming actions of LRF on LH secretion are functionally dissociable and that large elevations of LRF tend to favor release, while small LRF increments seem to promote priming preferentially.

Adult↗
PubMed1977

A comparison of the reproductive cycle of three species of Lemur.

The duration of the luteal phase and the 'proestrus' phase in three species of lemurs (Lemur macaco, Lemur catta, and Lemur variegatus) was determined by serum progesterone measurement. Total immunoreactive estrogens were measured and remained below 0.20 ng/ml except for an apparent peak of short duration during estrus. Circulating testosterone levels in males confirm previously described seasonal gonadal function. The reproductive cycle of the female lemur is discussed and compared to the cycles of estrous and menstrual animals.

Animals↗