PubMed Health⌕ Search

Biomedical subjects

W Beck

Publications and source records attributed to W Beck.

At least 127 records · Page 7Linked to original sources
PubMed1977

Desensitization of the dopaminergic inhibition of pituitary luteinizing hormone release by prolactin in ovariectomized rats.

Increase of plasma prolactin in chronically ovariectomized rats by transplanting pituitary glands from male rats to the kidney capsule reduced pituitary LH output for 1 week. At the end of this time, despite the fact that prolactin remained high, plasma LH levels rose to reach the value seen in ovariectomized control rats. High plasma prolactin did not affect FSH concentrations. Treatment of ovariectomized rats with apomorphine, a dopamine-receptor stimulating drug, reduced pituitary LH release in a dose-dependent way at doses of 1, 2, 5 and 10 mg/kg body weight. Higher doses either had no effect or they stimulated pituitary LH release. Apomorphine did not reduce pituitary LH secretion in chronically hyperprolactinaemic rats at doses which significantly inhibited LH release in ovariectomized animals. Plasma FSH levels were not affected by apomorphine treatment. In both groups of animals the drug reduced plasma prolactin levels to basal values, indicating that the dopamine agonist inhibits pituitary prolactin release by direct action on the pituitary gland. These results suggest that dopamine inhibits pituitary LH release, probably by reducing hypothalamic LH-releasing hormone release. The mechanism by which chronically high prolactin levels cause apomorphine to be less effective in reducing pituitary LH release may be a desensitization of some dopamine-receptive mechanism which is inhibitory to LH release.

Animals↗
PubMed1977

Functional independence of donor and recipient cardiac tissues of single and double heart transplant patients revealed by chronobiology.

3 total (single) and 1 double-heart-transplant patients were studied for temporal changes in the electrical events of cardiac function. Results of statistical analyses document the existence of circadian rhythms in the donor and recipient P--P or R--R intervals. However, for 1 total-heart-transplant patient studied at intervals during the year following implant and the double-heart-transplant patient 5 mth after surgery, the period (tau) of the rhythm in the P--P or R--R interval of the recipient tissue deviated greatly from that of 24.0 h. For the total-heart-transplant patient studied 1 mth prior to death, the tau was 32.3 h; for the double-heart-transplant patient, the tau was 29.0 h. In both patients, the donor heart tissue continued to exhibit a 24-h rhythm. These findings imply that changes in tau for the rhythm in P--P or R--R interval may reflect aspects of disrupted physiologic, feedback, regulatory mechanisms or perhaps graft rejection. Although additional study is required, the possibility that alteration in tau is associated with rejection is intriguing since if documented, then the noninvasive monitoring of ECG and subsequent analysis of data for significant deviations of tau from 24.0 h will be useful as an additional tool for monitoring host tolerance for the heart implant.

Bed Rest↗
PubMed1976

Left ventricular bypass using a cardiac allograft: hemodynamic studies.

Human allograft bypass of the failing left ventricle is an efficient and practical way of effecting short-term improvement in the overall hemodynamic status of patients. It is suggested that controlled sequential pacing of the donor heart would improve the overall hemodynamic result and better preserve function of the bypassed ventricle. Simultaneous bypass of the right ventricle might prevent the acute right heart failure seen during serious ventricular arrhythmias occurring in the recipient heart. Future indications for the technique in modified form could include severe biventricular failure and acute reversible forms of heart failure.

Cardiac Catheterization↗
PubMed1975

Corrective surgery for transposition of the great arteries.

The results of corrective surgery in 32 patients with transposition of the great arteries (TGA) are reviewed. Patients with TGA and associated defects comprised 47% of the series. The over-all long-term mortality rate was 31%. An acceptable mortality rate of 17,5% was achieved in simple TGA by using a Mustard repair. Good results were obtained with the Rastelli operation for patients with TGA, ventricular septal defect and severe pulmonary stenosis. Results were poor in patients with TGA and unrestricted ventricular septal defects, in whom palliative pulmonary artery banding or corrective surgery under 6 months of age is advocated. The major late complication was patch contraction resulting in pulmonary or systemic venous obstruction.

Aortic Coarctation↗
PubMed1975

[Results of the total hip replacement operations (author's transl)].

A review of the hip replacement operations performed by the department of orthopaedics of the University Hospital of Freiburg follows. The operation brought "very good" results for 14.4% of those operated upon, "good" results for 50.6% and satisfactory results for 29.7%. The results of the operation were unsatisfactory for 5.6% of the patients. In view of the possible complications, the results will be discussed.

Adult↗