Search PubMed⌕ Search

Biomedical subjects

W Hansel

Publications and source records attributed to W Hansel.

At least 109 records · Page 6Linked to original sources
PubMed1979

Steroidogenesis and prostaglandin synthesis by cultured bovine blastocysts.

Bovine blastocysts were collected at Days 13, 15 and 16 and placed in TCM-199 supplemented with 5% fetal calf serum; some blastocysts were immediately frozen while the others were cultured for 48 h and then frozen. Samples (tissue + medium, 5--12/group) were thawed, homogenized and analysed by radioimmunoassays. Measurable amounts of progesterone were found in all blastocysts but values were higher (P less than 0.01) after culture. Testosterone was not found in the cultured or uncultured blastocysts at Day 13, but was detectable on Days 15 and 16 and in greater amounts (P less than 0.05) in the cultured blastocysts. PGF and PGE-2 were increased (P less than 0.05) in the cultured blastocysts in all 3 days. Oestradiol was measurable in some but not all blastocysts. It is suggested that PG synthetase and enzymes capable of synthesizing progesterone, testosterone and, possibly, oestradiol are present in these early bovine blastocysts.

Animals↗
PubMed1979

Modulation of thecal progesterone secretion by estradiol-17 beta.

The effects of estradiol-17 beta on progesterone secretion by isolated bovine theca interna were studied. Preparations of theca interna were obtained from preovulatory follicles of Holstein heifers (n = 5) prior to the endogenous LH surge and cultured for 3 days in a defined medium containing various concentrations of estradiol (0, 0.001, 0.01, 0.1, 1, or 10 microgram/ml). Secretion of progesterone by control theca was low during the first 24 h of culture and increased steadily during the subsequent 48 h. The lowest concentration of estradiol (0.001 microgram/ml) significantly stimulated thecal progesterone production, while higher concentrations (0.1, 1, and 10 microgram/ml) significantly inhibited secretion of progesterone. Estradiol content of the follicular fluid of these preovulatory follicles and several others (n = 13) averaged 1.5 microgram/ml +/- 0.1 (SEM). It is concluded that bovine theca interna is capable of secreting progesterone, that high intrafollicular concentrations of estradiol may inhibit thecal progesterone production in vivo prior to the LH surge, and that estradiol concentration may be be an important modulating factor in the control of follicular progesterone secretion.

Animals↗
PubMed1977

Prostaglandin F2alpha induced luteolysis, hypothermia, and abortions in beagle bitches.

Luteal phase plasma progesterone was radioimmunoassayed in samples collected before, during, and after a 72 hr treatment period during which Beagle bitches received repeated i.m. injections of prostaglandin F2alpha (n=17) or saline (n=3). PGF2alpha (20 ug/kg every 8 hr or 30 ug/kg every 12 hr) was administered to 7 pregnant and 8 nonpregnant bitches during the mid or late luteal phase of the cycle (Day 25-58) and to 2 nonpregnant bitches during the early luteal phase (Days 5 and 20). Progesterone was depressed from pretreatment levels (3-40 ng/ml) in each of the 15 bitches given PGF2alpha after Day 25 of the cycle. Mean progesterone (ng/ml plasma) at -24, 0, 12, 24, 36, 48, 60, 72 and 96 hr from the initial PGF2alpha injection were 16.6, 15.6, 9.3, 5.1, 2.1, 1.5, 1.4, 1.1 and 1.1 (+/- 0.9, n=15). Thereafter, progesterone was nondetectable in the 8 nonpregnant bitches and in 4 pregnant bitches that aborted. Abortions occurred when progesterone was depressed to 0.6-1.4 ng/ml, 56-80 hr after starting PGF2alpha treatment on Days 33-53 of the cycle. Three pregnant bitches did not abort when progesterone was depressed to a mean low value of 2.1 ng/ml during PGF2alpha treatments begun on Day 31-40 of pregnancy. Progesterone in these bitches recovered to 5-10 ng/ml and was maintained until the normal prepartum decline. Since PGF2alpha can induce complete luteolysis it may be of use as an abortifacient in the bitch. A transient fall in rectal temperature occurred in each of 12 luteal phase bitches injected with PGF2alpha (20 ug/kg, i.m.). The hypothermia was detectable within 15 min, maximal at 45-60 min, and averaged 1.39 degrees similarly treated. In six luteal phase bitches, plasma progesterone fell 20-45% within the 15 min required to observe a consistent decline in rectal temperature following PGF2alpha administratic effect and dependent on a fall in progesterone.

Abortion, Induced↗
PubMed1976

Hormonal changes associated with experimentally produced cystic ovaries in the cow.

Cystic ovaries were experimentally produced by i.m. injection of 5 mg oestradiol valerate on Day 16 of the oestrous cycle or by s.c. injection of 100 ml antiserum to bovine LH before the onset of oestrus. The length of the cycle after both treatments was altered. The cysts formed after oestradiol injection were relatively small (2-5-3 cm diameter) and thin-walled, and were accompanied by relatively low plasma oestrone and high oestradiol levels; those after LH antiserum treatment were large (5-0-6-0 cm) and firm and associated with relatively low oestradiol and high oestrone levels. The results of the hormone assays after treatment support the theory that cystic ovaries could result from premature LH release or an insufficiency of LH at the time of ovulation.

Animals↗
PubMed1976

Plasma growth hormone and insulin during early lactation in cows fed silage based diets.

Peripheral plasma insulin, growth hormone, and blood glucose were determined in 24 dairy cows during early lactation. Blood samples were obtained at 4-day intervals during the first 56 days of experimental lactations 1 and 3 of a 3-lactation experiment. The cows were divided equally among three groups and fed one of the following forage rations for three consecutive lactations: corn silage (18.2 kg/day) plus alfalfa-timothy hay ad libitum; corn silage (18.2 kg/day) plus alfalfa-timothy silage ad libitum; or corn silage ad libitum. These diets were continued throughout the intervening dry periods except in the latter group where corn silage intake was limited if individual animals exhibited excessive body weight gain. Four animals in each group received prepartum supplemental concentrates. The remaining four animals received no prepartum concentrate supplementation. Following parturition, concentrates were fed in increasing amounts to a maximum of 14.6 kg/day during the first 56 days of lactation. Plasma insulin, growth hormone, and blood glucose were not affected by forage diet or prepartum supplemental concentrate feeding. Plasma insulin and blood glucose increased and plasma growth hormone decreased with time after parturition. These changes were correlated with nutrient intake which increased during the experiment. Changes in plasma insulin and growth hormone are related to metabolic adjustments during early lactation.

Animal Feed↗
PubMed1976

Influence of human chorionic gonadotropin on pregnancy rates in lactating dairy and beef cows.

Single subcutaneous injection of 1500 IU human chorionic gonadotropin or placebo injections were given at the time of insemination in lactating dairy and beef cows to determine their effects on rates of pregnancy. Pregnancy rates at first service in 161 control and 145 treated dairy cows were 52.8% and 44.8%, respectively. Similar rates for 136 control and 145 treated beef cows were 54.4% and 54.5%. Injections of human chorionic gonadotropin were not effective in stimulating conception rates in lactating dairy or beer cows under field conditions.

Animals↗
PubMed1976

Lipoprotein lipase activity in the bovine corpus luteum during the estrous cycle and early pregnancy.

Lipolytic activity measured at pH 8.6 in bovine corpora lutea exhibited classical properties of lipoprotein lipase (LPL) in terms of serum and heparin stimulation and NaCl inhibition. LPL activity was measured in 23 corpora lutea collected at different stages of the estrous cycle and early pregnancy. The LPL activity in cyclic corpora lutea (mumole FA released/hr/100 mg acetone powder) was low at Days 4-8 of the estrous cycle (3.1 +/- 1.5: mean +/- SE) and at Days 19-20 (1.6 +/- 0.6). However, high activity of the enzyme was found at Days 12-15 of the cycle (11.8 +/- 1.8); these concentrations were significantly (P less than 0.01) elevated over those found at Days 4-8 and 19-20. The enzyme activity began to decline at Days 16-18 of the estrous cycle (5.1 +/- 1.7). Low enzyme activity was found in the corpora lutea removed from two cows at Day 22 of pregnancy. Progesterone concentrations were measured in 16 of the 23 corpora lutea and a good correlation (r = 0.75, P less than 0.01) was found between lipoprotein lipase and progesterone concentrations of the tissue. The data suggest that LPL may be involved in controlling the transfer of fatty acids, including arachidonic, from plasma lipoproteins to luteal tissue.

Animals↗