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Biomedical subjects

E Grunert

Publications and source records attributed to E Grunert.

At least 73 records · Page 4Linked to original sources
PubMed1987

Influence of luteinizing hormone and prostaglandin F(2alpha) on progesterone secretion in superfused minced bovine luteal tissue in the early stage of the estrous cycle.

Minced luteal tissue of bovine corpora lutea from Day 4, 5, and 6 of the estrous cycle (n = 4 corpora lutea each) was superfused for 9 h, and the progesterone secretion under the influence of 100 ng luteinizing hormone (LH)/ml and/or 1,000 ng prostaglandin F(2alpha) (PGF(2alpha))/ml was determined. In vivo, this period of the estrous cycle is characterized by a transition from PGF(2alpha) refractoriness to PGF(2alpha) sensitivity. The investigations were carried out in order to examine whether this transition is reflected by a change in the hormone secretion pattern in vitro. The basal secretion was higher on Day 6 than on Day 4 and 5 (P < 0.01). PGF(2alpha) slightly increased the progesterone secretion, but there was no statistically significant difference (P > 0.05). LH, however, stimulated the progesterone secretion by about 30% in luteal tissue collected from Day 4 and 5 (P < 0.01). In luteal tissue collected from Day 6, the LH-induced increase in hormone secretion was not statistically significant due to two corpora lutea that showed no response at all to LH. The progesterone secretion of the two other corpora lutea, however, was increased by 30% (P < 0.01). When PGF(2alpha) and LH were simultaneously added, the LH-induced progesterone secretion was not inhibited; PGF(2alpha) even seemed to intensify the action of LH. The difference between the hormone secretion under the influence of LH alone and that under the influence of a combination of LH and PGF(2alpha), however, was not statistically significant. It is concluded that in cattle the end of the refractoriness to PGF(2alpha) in vivo is not reflected by a corresponding change of the hormone secretion pattern in vitro.

Journal Article↗
PubMed1987

In-vitro steroid secretion of tertiary atretic bovine follicles in a superfusion system correlated to their histological features.

In monotocus mammals most of the tertiary follicles are atretic. The experimental design of a blind study was used to evaluate the steroid secretion pattern and histological features of atretic bovine follicles. Steroidogenesis of the vesicles was studied with the aid of a superfusion system, and the superfused follicles were evaluated independently using the histological classification elaborated by Marion et al. Twelve single atretic follicles removed during the follicular and luteal phases of twelve cows were superfused for 10 h and then histologically processed. Follicles in early and definite contracting atresia secreted predominantly testosterone, whereas follicles in definite cystic, advanced contracting and late atresia secreted predominantly progesterone. Such secretion was independent of the stage of the oestrus cycle of the animal, so that follicles with the same histological pattern had a characteristic steroid secretion pattern, which was not influenced by the stage of the oestrus cycle at the time of follicular removal. In conclusion, atretic follicles should be considered significant endocrine organs.

Animals↗
PubMed1987

Influence of luteinizing hormone and prostaglandin F2 alpha on progesterone secretion in superfused bovine luteal tissue slices.

Tissue slices from bovine corpus luteum from Days 12 or 13 of the oestrous cycle were superfused for 8 h, and the progesterone secretion under the influence of prostaglandin F2 alpha (PGF2 alpha) and/or LH was measured. PGF2 alpha at concentrations of 0.28 to 2800 nmol/l medium did not affect the basal progesterone secretion, whereas higher doses (7000 to 28,000 nmol/l) induced a slight increase in hormone secretion. LH, 3.4 nmol/l, caused an increase in the progesterone concentration in superfusates which exceeded the control levels (P less than 0.01). This luteotropic effect of LH was not influenced by simultaneous addition of 28 to 2800 nmol/l PGF2 alpha. PGF2 alpha, 2800 nmol/l, did not inhibit progesterone secretion, when administered together with 0.034 to 34 nmol LH/l. Pre-superfusion with 2800 nmol/l PGF2 alpha had no effect on the LH-stimulated increase in progesterone secretion. It is concluded that in cattle, a direct cellular effect of PGF2 alpha, antagonizing the luteotropic function of LH, may be of less importance than other possible direct and indirect PGF2 alpha actions.

Animals↗
PubMed1984

Neonatal respiratory distress syndrome in the calf.

Thirty-five calves were delivered by caesarean section near to term. During the operation amniotic fluid was collected for determination of the lecithin/sphingomyelin (L/S) ratio. Clinical examination of the calves and analysis of blood gas concentration (venous blood) were carried out within the first hour of life. Fifteen out of 35 calves under examination did not show clinical or blood gas disorders in the course of the first hour of life. In these calves, the L/S ratio, which represents a measure for the maturity of the surfactant system, averaged 2.6. The other 20 calves, however, developed a respiratory distress syndrome together with a progressive respiratory and metabolic acidosis within the first hour of life. The L/S ratio in the animals affected with respiratory distress syndrome reached an average value of 1.5 which was significantly below that of the calves not suffering from respiratory distress. Eleven of the 20 calves which developed respiratory distress syndrome died within the first 60 hours of life. The most striking findings in the post mortem examinations of these animals were intracranial haemorrhages and pulmonary lesions (hyaline membranes, interstitial and alveolar oedema). On the basis of the significantly lower L/S ratio and the post mortem findings, it is to be assumed that the respiratory distress syndrome in calves, equally with that in infants, is attributable to a surfactant deficiency.

Amniotic Fluid↗