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Biomedical subjects

G Sturm

Publications and source records attributed to G Sturm.

At least 73 records · Page 4Linked to original sources
PubMed1979

Study of testicular feedback in male rats using artificial cryptorchidism as a model.

Plasma LH, FSH and testosterone were measured in testosterone-treated and untreated cryptorchid and castrated male rats. Exogenous testosterone prevented the increase in basal LH but not FSH levels seen in the untreated cryptorchids. Increases in plasma LH and FSH in response to LH-RH were greater in the cryptorchid as compared to the control group and this could not be reversed by exogenous testosterone, suggesting that spermatogenesis-related feedback factors regulate LH as well as FSH at the pituitary level in the intact rat. The results were consistent with a reduced but nevertheless significant secretion of inhibin by the cryptorchid testis. Basal plasma testosterone levels and ventral prostate weights were not significantly different from intact animals.

Androgens↗
PubMed1979

Purification of "inhibin" from human ovarian follicular fluid.

Following the earlier demonstration of inhibin-like activity in human ovarian follicular fluid a method for its purification to apparent homogeneity is described. The fluid was converted to acetone powder and subjected sequentially to ammonium sulphate fractionation, gel chromatography on Sephadex G-200, continuous gradient ion-exchange chromatography on DEAE-cellulose, first with a pH gradient from 8.0 to 4.0 and then with a NaCl gradient to 1 M at pH 5.2. The active fraction from this step was subjected to gel filtration on Sephadex G-100 and finally passed through an Amicon Centriflo membrane CF-25 (cut off point: 25,000 m.w.). The ultrafiltrate was homogeneous by SDS-polyacrylamide gel electrophoresis, had a molecular weight of the order of 23 000 and was capable of suppressing serum gonadotrophin levels in the castrated male rats in as low a dose as 25 microgram/rat.

Adult↗
PubMed1978

[Inhibin-like activity in human ovarian follicular fluid (author's transl)].

A steroid-free proteinaceous substance with inhibin-like activity has been extracted from human ovarian follicular fluid by alcohol precipitation. This substance was capable of inhibiting the ovarian weight increase of hCG-treated immature female rats and also of suppressing the post-castration rise of serum FSH levels in immature male rats. Follicular fluid from small follicls obtained from regularly cycling women was--on the basis of protein- found to be more active than cystic follicular fluid obtained from a premenopausal woman. The possible role of inhibin in the regulation of human ovarian cycle has been discussed.

Animals↗
PubMed1978

Intra-ovarian formation of steroid sulphates: measurement and influence of gonadotrophins.

The steroid sulphokinase activity in 105 000 g supernatant fractions from rat and bovine ovarian tissue has been determined by measuring the radioactivity incorporated into conjugated steroids after incubation with 14C-labelled androgens and oestrogens. The enzyme from bovine ovaries was partially characterized, changes in its activity with pH were measured and Km values of 30, 10 and 4 mumol/1 were obtained for testosterone, oestradiol and oestrone respectively. The rate of formation of sulphates from oestrogens by preparations of bovine luteal tissue was 10--20 times higher than the rate of formation by follicular tissue (P less than 0.001), but both tissues exhibited similar rate of sulphate formation with testosterone. Sulphation of dehydroepiandrosterone by the ovaries of gonadotrophin-treated rats did not differ from that observed in the control group, whereas sulphation of oestrone was nearly three times greater in ovaries obtained from rats treated with gonadotrophins (P less than 0.005). Furthermore, a comparison of steriod sulphation in the ovaries of pseudopregnant and normal cyclic rats showed that the sulphation of oestrone was about six times greater during pseudopregnancy. These observations suggest that the formation of oestrogen, but not androgen, sulphates by ovarian aryl sulphokinase differs in follicular and luteal tissue and may be gonadotrophin dependent. The greater capacity of luteal, compared with follicular, tissue for the sulphation of oestrogens may be a control mechanism for steroidogenesis within the ovarian tissue.

Animals↗
PubMed1977

[The action of 1-aminoadamantane. Comparative studies with isolated nerve endings and thrombocytes on the release of serotonin and dopamine].

Nerve endings isolated from rat brain accumulate exogenous serotonin and dopamine. Both biogenic amines are released from nerve endings as well by means of electrical stimulation with rectangular pulses of alternating polarity as by incubation with 5 X 10(-4) to 5 X 10(-5) M solutions of the adamantane derivatives 1-aminoadamantane hydrochloride (D 1) and 1-amino-3,5-dimethyladamantane hydrochloride (memantine, D 145). The electrically stimulated liberation is small but is significantly increased after simultaneous incubation of the nerve endings with subthreshold concentrations of 1-aminoadamantanes (5X10(-6) to 5X10(-5) M). The reuptake of released serotonin is noncompetitively inhibited by 1-aminoadamantanes. Also in blood platelets frequently used as model cells of the nerve endings the serotonin uptake is inhibited by small concentrations of D 145, 10(-5) to 2X10(-4) M. High concentrations of D 145- greater than 2X10(-3) M, induce the "release-reaction", the simultaneous liberation of serotonin, ATP, and ADP. In the concentration range of 2X10(-4) to 2X10(-3) M D 145 only serotonin is set free.

Amantadine↗
PubMed1977

[Ultrasonics of ovarian changes under gonadotrophine stimulation (author's transl)].

It is known that there are difficulties in timing of ovulation induction under gonadotrophines. The reason is that investigation parameters used so far only permit indirect quantitative statements. Ultrasonics permit the direct presentation of ovaries, cystic structure-follicles, registration of their number and size as well as control of the further development. Using an typical case, possibilities with ultrasonics are demonstrated. Ovulation was induced when one follicle (0 23 mm) dominated over two others (0 17 mm), and a corpus-luteum-cyst and the pregnancy were observed. Two gestational-sacs perished during bleedings in the 9th week of pregnancy. The normal pregnancy was controlled with ultrasonics until delivery. Ultrasonic equipment was Vidoson 635 S by Siemens and Diasonograph NE 4102/B by Nuclear Enterprises.

Chorionic Gonadotropin↗
PubMed1976

Investigations into the preservation of human ovaries by means of a cryoprotectivum.

Human ovaries in the phase of follicular ripening were treated by means of a cryoprotectivum immediately after their removal. They were kept at --18degrees C for up to 8 weeks. After having gradually been thawed the ovaries were in vitro connected to a perfusion system. When completely revitalized they were examined in the steady-state for their metabolic behaviour. It was found that in comparison with the untreated controls, depending on the period of preservation, the oxygen consumption and the estrogen secretion had decreased, while the glucose absorption and lactate production had increased. As a morphological substrate a minor oedema was established in the tissue in the histological control after a preservation period of 2 months. This was mainly localized around the arteries. The method can be regarded as suitable for the preservation of ovaries for a limited period of time. It is possible to maintained a metabolism that can still be regarded as functioning.

Adult↗
PubMed1976

Effect of 13-Nle-motilin on small intestinal transit time in healthy subjects.

In 6 female subjects without gastrointestinal diseases, 13-norleucine motilin (13-Nle-M) synthetic and biological analogue of the duodenal polypeptide, motilin, caused acceleration of intestinal transit time. Intravenous infusion of 0.4 mug/kg-h of 13-Nle-M reduced mean transit time by 50 percent. No side effects occurred during infusion of the polypeptide. Radiographic appearance of small intestinal peristalsis and mucosal relief was not influenced by 13-Nle-M.

Female↗
PubMed1975

Testosterone undecanoate: a new orally active androgen.

Oral testosterone undecanoate (TU) in arachis oil has been evaluated with a view to its possible use as a means of androgen replacement therapy. A single 100 mg dose was found to elevate plasma androgen levels and urinary 17-ketosteroid excretion in 6 normal men. Ninety mg/day and 60 mg/day doses taken by a hypogonadal man resulted in sustained levels of androgen which appeared physiological when measured by radioimmunoassay without chromatography. However, upon separation of the steroids by chromatography it was found that much of the androgen present was in fact dihydrotestosterone not testosterone. Both TU and dihydrotestosterone undecanoate were detected in plasma by gas chromatography and it is suggested that the ester is absorbed as such from the intestine and the unesterified steroid subsequently released by hydrolysis. The convenience of oral administration, the resulting prolonged elevated plasma androgen levels and the probable lack of deleterious effects on the liver may render oral TU of value where androgen replacement therapy is indicated.

17-Ketosteroids↗