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Biomedical subjects

E Haase

Publications and source records attributed to E Haase.

At least 37 records · Page 2Linked to original sources
PubMed1983

Identification of 5 alpha-dihydrotestosterone in avian plasma.

Conscious adult domestic mallard drakes were intravenously injected with tritiated testosterone. After 30 min of in vivo conversion the steroids were extracted from the plasma and submitted to thin-layer chromatography (TLC). Using radiogas chromatography, labeled 5 alpha-dihydrotestosterone (5 alpha-DHT), androsterone, and epiandrosterone could be identified in the androstanolone fraction. 5 alpha-DHT was separated in a second TLC system and definitively identified by recrystallization to constant specific activity.

Animals↗
PubMed1983

The annual reproductive cycle in mallards.

In wild mallard drakes plasma FSH and LH levels were elevated at the height of the breeding season in spring, decreased towards the end of the reproductive phase and were low during the time of photorefractoriness in summer, when the testes were regressed. In contrast plasma prolactin concentrations increased only towards the end of the breeding season and were at their annual height during the summer. Castration of photorefractory mallards caused a steep rise of plasma LH levels indicating that the testes were involved in the maintenance of the low LH concentrations during the refractory period. In these drakes LH titers remained high throughout the year and, thus, in the absence of the testes the birds did not become photorefractory. In photorefractory drakes removal of 90% of the testicular tissue not only increased plasma LH levels but induced complete spermatogenesis in the testicular remains within 6 weeks. Therefore it seems that photorefractoriness in mallards is due to an increased sensitivity of the hypothalamo-hypophyseal system to the negative feedback action of testicular androgens. After injection of tritiated testosterone the hypothalamus, anterior pituitary and testes, but not other organs studied, took up more radioactivity during the refractory phase than at the height of the breeding season. It is speculated that the increased sensitivity of the hypothalamo-hypophyseal unit to the negative androgenic feedback during photorefractoriness depends on an increased number of androgen receptors in these structures which, again, could be due to the elevated prolactin levels during this phase of the annual cycle.

Animals↗
PubMed1981

Isolation of yeast mutants sensitive to the bifunctional alkylating agent nitrogen mustard.

Mutants of Saccharomyces cerevisiae with enhanced sensitivity to the DNA cross-linking agent nitrogen mustard (HN2) have been isolated and partially characterized with respect to their phenotypic and genetic properties. The screening technique, based on HN2-sensitivity as sole criterion, yields approxiamtely 1 sensitive isolate in 200 clones when applied to an intensively mutagenized population of a resistant parent strain. Mutants characterized so far are all due to recessive nuclear genes and represent at least seven complementation groups. They exhibit different degrees as well as different patterns of sensitivity towards monofunctional and bifunctional alkylating agents, and ultraviolet light.

Alkylating Agents↗
PubMed1981

[Diagnosis and therapy of hepatoblastoma. Successful treatment of an inoperable hepatoblastoma and review of the literature (author's transl)].

A review of the literature shows minimal success in relation to the treatment of hepato-blastoma. Recent improvements have been related to better techniques of liver resection. No final therapeutic recommendations can be made but prophylactic chemotherapy is indicated. The authors present a surprisingly successful patient who had a non-resectable hepato-blastoma and who is alive 8 years later without symptoms. In spite of radiotherapy, and chemotherapy there have been no obvious somatic changes which could be attributed to the treatment. The effect of treatment on the gonads is a feature that will have to be considered at a later date.

Antineoplastic Agents↗
PubMed1980

[Autoradiography of the brain of bramblings (Fringilla montifringilla L.) following the injection of 3H-testosterone].

The topographic distribution of 3H-testosterone and/or its metabolites in brains of Bramblings (Fringilla montifringilla L.) was studied autoradiographically and the intensity of labeling was estimated semi-quantitatively. The highest accumulation of radioactivity was found in nuclei of the preoptic region and the hypothalamus (fig. 2--fig. 5). Cells of the Nucleus preopticus medialis (POM), Nucleus paraventricularis magnocellularis (PVM) and Nucleus lateralis hypothalami posterioris (PLH) showed medium or high intensity labelling, while cells of the Nucleus preopticus paraventricularis magnocellularis (PPM), Nucleus hypothalamicus anterior medialis (HAM), Nucleus hypothalamicus posterior medialis (HPM), and the infundibular area (TU) contained low or medium concentrations of radioactivity. The role of these nuclei in the gonadal feedback on the hypothalamo-hypophyseal system, in the control of the annual reproductive cycle and as effective sites of testosterone on sexual behaviour are discussed. Moderate accumulations of radioactivity were also observed in the Hyperstriatum ventrale of the telencephalon (HV, fig. 5), the Nucleus intercollicularis of the mesencephalon (ICo, fig. 6) and the Nucleus nervi hypoglossi (nXII) of the medulla. These structures are known to influence bird song and other vocalisations. Low labelled cells were found in the periventricular zone of the neostriatum, in the lateral septum, and more irregularly in other areas (fig. 1--6). The pattern of distribution of 3H-testosterone in the brain of Bramblings was similar to that in other birds (table 1).

Animals↗
PubMed1979

[Comparative and quantitative ultrastructural study of the olfactory organs of four strains of domestic pigeons].

1. By counting the axons per micron 2 on electronmicrographs of cross-sectioned olfactory nerves and multiplying this number by the area of the cross-sectioned nerves, the number of olfactory receptors was determined in 4 breeds of domestic pigeons including homing pigeons. 2. The total number of olfactory receptors varied between 3.0 and 7.4 . 10(6). It significantly depended on the body size of the pigeons. There was no evidence for differences in the number of olfactory receptors between the breeds independent of body size. 3. No differences in the relative size of the olfactory bulbs could be detected between the breeds. 4. The ultrastructure of the olfactory epithelium was basically similar to that of other birds. The covering mucus layer was revealed to be a secretion product of both the olfactory glands of Bowman and the olfactory supporting cells. No differences were observed in the ultrastructure of the olfactory region between the four breeds investigated.

Animals↗
PubMed1976

Effects of seasonal and social factors on testicular activity and hormone levels in domestic pigeons.

Testicular morphology and plasma concentrations of luteinizing hormone (LH), testosterone, progesterone, and estradiol-17beta were compared in paired (n = 8) and unpaired (n = 7) racing pigeons killed in December. The birds were housed mixed together under natural lighting conditions in two unheated lofts which contained no nesting facilities, in Kiel (54 degrees N), Germany. The paired birds had been paired for at least two months. Testicular weights and diameters of tubules were significantly higher (p less than 0.05) in paired (1.64 +/- 0.25 gm; 218 +/- 12 mum) than in unpaired birds (0.79 +/- 0.25 gm; 165 +/- 20 mum). The testes of paired birds were spermatogenetically more active than those of unpaired birds. Plasma concentrations of some hormones concerned with reproduction were, in paired and unpaired birds respectively: LH, 2.28 +/- 0.43 ng/ml and 0.98 +/- 0.36 ng/ml (significantly different, p less than 0.1); testosterone, 1.24 +/- 0.51 ng/ml and 0.59 +/- 0.12 ng/ml (not significantly different); progesterone, 0.58 +/- 0.08 ng/ml and 0.90 +/- 0.12 ng/ml (sifnificantly different, p less than 0.05); and estradiol-17beta, 16.3 +/- 0.95 pg/ml and 18.7 +/- 2.25 pg/ml (not significantly different). Thus, the stimulatory effects of a mate on gonadotropin secretion and gonadal activity which have often been reported for female ring doves and domestic pigeons are also demonstrable in males during the late fall. Seasonal testicular regression in the unpaired males at this time of year was not prevented by the presence of paired females.

Animals↗
PubMed1975

Immunofluorescent localization of sites binding anti-synthetic LHRH serum in the median eminence of the greenfinch (Chloris chloris L.).

With an indirect immunofluorescence technique and an antiserum raised against synthetic LHRH, immunofluorescent granules were observed in fine radially oriented fibres in the palisade layer of the zoma externa in both the anterior and the posterior divisions of the median eminence in the greenfinch. There was no specific immunofluorescence in the tractus supraoptico-hypophyseus. It is concluded that the greenfinch median eminence contains material which is similar to mammalian LHRH.

Animals↗
PubMed1975

Annual cycle of plasma luteinizing hormone concentrations in wild mallard drakes.

Plasma LH concentrations were followed in 9 individually marked wild mallard drakes in Kiel (54 degrees N) for one year at monthly intervals. Mean LH levels increased during the spring and reached the annual maximum in April and May. In June when testicular regressions occurs, the LH titer sharply decreased and was lower than at any other phase of the annual cycle. In late fall mean plasma LH concentrations increased and, whilst not reaching the values observed during the breeding season, remained relatively high during the winter. Thus, in the mallard LH can be released under short and long daily photo-periods.

Animals↗