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Biomedical subjects

W Hansel

Publications and source records attributed to W Hansel.

At least 127 records · Page 7Linked to original sources
PubMed1976

Steroid synthesis by ovarian follicles in response to LH and PGF2alpha.

Ovarian follicles isolated from bovine ovaries at the 16th and 17th days of the estrous cycle were minced, pooled, and incubated in Krebs-Ringer bicarbonate buffer at 37degrees for 2 hr. Samples were analyzed for testosterone, estrogens, and progesterone by radioimmunoassays. Incubation alone failed to cause an increase in testosterone (12.1 vs 29.3 ng/g of tissue; P is greater than 0.05). Additions of 5 mug/ml of bovine LH or prostaglandin F2alpha caused increases in testosterone synthesis to 125.0 (Pis less than 0.01) and 103 ng/g (P is less than 0.01). Estradiol synthesis was also stimulated by LH (P is less than 0.01). However, stimulation due to addition of PGF2alpha (5.1 to 15 ng/g) was not significant (P is greater than 0.05). PGF2alpha also caused a slight but nonsignificant increase in estrone secretion. Incubation failed to increase the progesterone concentration (623 vs 774 ng/g of tissue; P is greater than 0.05). There was no increase in progesterone synthesis due to addition of either LH or PGF2alpha (P is greater than 0.05). The results show that bovine follicles produce much more testosterone than estrogen and that both LH and PGF2alpha significantly stimulate testosterone synthesis in bovine follicular tissue without increasing net progesterone biosynthesis.

Animals↗
PubMed1975

Plasma adrenocorticoid response to corticotropin in dairy cattle fed high silage diets.

Responses of plasma corticoids to adrenocorticotropic hormone (.32 U/kg body weight) administered during early lactation were measured in dairy cattle consuming large amounts of concentrate feeds and one of the following forage diets: alfalfa-timothy hay plus corn silage, alfalfa-timothy hay crop silage plus corn silage, or corn silage. Concentrations of plasma corticoids increased to maximum in all groups within 60 to 90 min. Concentrations remained at near maximum for 4 to 5 h and then declined to baseline. Maximum corticoid concentrations following adrenocorticotropic hormone injection differed among forage treatment groups. Responses of corn silage and hay crop silage groups (46.7 +/- 1.1 and 50.1 +/- 2.4 ng/ml) did not differ but were less than those in the hay group (65.5 +/- 2.9 ng/ml). Response measured as area under the curve of plasma corticoid response also differed among forage treatments: hay 443 +/- 17 h (ng/ml) is greater than hay crop silage 334 +/- 34 is greater than corn silage 245 +/- 36. Results are discussed in terms of stress susceptibility in dairy cattle consuming diets containing large amounts of silage.

Adrenal Cortex Hormones↗
PubMed1975

Levels of prostaglandin F (PGF) in bovine endometrium uterine venous, ovarian arterial and jugular plasma during the estrous cycle (38789).

Prostaglandins F (PGF) were measured in uterine vein, ovarian artery, and jugular vein plasma and in the endometrial tissues at various times during the bovine estrous cycle, and were compared to peripheral plasma progesterone levels. Four groups of heifers at days 1-5, 10-14, 15-17 and 20-0 of the estrous cycle were studied. Low levels of PGF (48 plus or minus 12 ng/g dry tissue were measured in the endometrium on days 1-14 of the cycle. Higher values (131 plus or minus 9.0) were found at days 15 until the day of estrus (p less than 0.001). Similarly, very low levels of PGF were observed in the uterine vein plasma at days 1-14 (0.162) plus or minus 0.044) ng/mlM plus or minus S.E.), whereas on days 15 until the day of estrus the levels ranged from 1.5 to 3.0 ng/ml. The increases in uterine vein PGF on day 15 occurred even while peripheral plasma progesterone levels were still high. However, PGF was not elevated in either the ovarian artery or the jugular vein at any time during the cycle, even when uterine vein levels were greatly elevated. No differences in PGF content were detected in endometrial tissue from uterine horns adjacent or opposite to the functional corpus luteum.

Animals↗
PubMed1975

Arachidonic acid and bocine corpus luteum function (38514).

Injections of arachidonic acid directly into the corpora lutea of normal cattle at the 12th or 13th day of the estrous cycle resulted in (a) a decline in jugular vein plasma progesterone levels from an average of 6 ng/ml to 2.5 ng/ml (p smaller than0.05), (b) an immediate rise in PGF levels in ovarian venous plasma, and (c) a sharp rise in jugular vein plasma estrogen levels. Jugular plasma estrogen peaks were associated with each ovarian vein PGF Peak in each animal; jugular plasma LH levels did not change. These results show that the bovine ovary can convert arachidonic acid to PGF and that arachidonic acid administered directly into the corpus luteum results in partial regression of the corpus luteum.PGF appears to stimulate estrogen production by the ovary in the absence of measurable changes of plasma LH.

Animals↗