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Biomedical subjects

B Hoffmann

Publications and source records attributed to B Hoffmann.

At least 199 records · Page 11Linked to original sources
PubMed1983

Estrogen agonistic and antagonistic action of 8 non-steroidal antiestrogens on progestin receptor induction in rat pituitary gland and uterus.

All 8 non-steroidal antiestrogens tested considerably increased progestin receptor concentration in the uterus and, to a lesser extent, in the pituitary of ovariectomized rats. However, the pituitary was more sensitive than the uterus to the estrogen antagonistic action of these compounds, in that monohydroxytamoxifen, LY 117,018, enclomiphene, nitromifen, nafoxidine and trans-tamoxifen completely blocked progestin receptor induction by estradiol benzoate. In these tissues the order of the in vitro binding affinity of antiestrogens to cytoplasmic estrogen receptors was not correlated with either their in vivo estrogen agonistic or antagonistic potency.

Animals↗
PubMed1983

Physiological effects of dynamic hand work in subjects of different age and sex.

Thirty untrained subjects (group 1: 10 female, 20-30 years; group 2: 10 female, 36-46 years; group 3: 10 males, 20-30 years) performed dynamic hand work on a hand-grip dynamometer at loads varying from 20 to 100% MVC and three different working frequencies (20, 40, and 60 cpm). The mechanical muscle activity, the iEMG and the R-R interval were measured throughout the exercise. Before and after each exercise, the maximal hand-grip force (MVC) was determined together with the iEMG and the R-R interval. With the loads increasing gradually, the mean values of the duration of the contraction phase and of the iEMG of the four muscles increased in all test groups, but the duration of the rest phase and R-R interval decreased. Through an Analysis of Variance, evidence of systematic differences between the test groups was significant for the R-R interval only, while the effects of the loads (with exception of the rest phase) and of the working frequency proved significant for all parameters. The MVC, the iEMG and the R-R interval measured before and after the exercise did not show significant differences. This indicates that the exercise was not fatiguing.

Adult↗
PubMed1983

Use of radioimmunoassay procedures for the determination of sex hormones in animal tissues.

Radioimmunoassay methods for the determination of sex steroids and other compounds with sex hormone-like activities in various edible animal tissues and endocrine glands have been developed. Reliability of these methods, allowing quantification in a range of 10(-11) M, has been adequately demonstrated. In any case the necessary extraction procedures could be kept feasible as a result of the binding characteristics of the antisera available. When applied in respect to monitor for residues of anabolic sex hormones in edible tissues of veal calves, physiological baseline levels of some endogenous "anabolic" steroids (like testosterone, oestrogens) were established; in the case of xenobiotics residues at the scheduled time of slaughter could be quantified (trenbolone) and a regulatory method to implement the ban of diethylstilbestrol was introduced.

Adipose Tissue↗
PubMed1983

Estrogen receptor translocation and replenishment in rat hypothalamus and pituitary gland after the application of catecholestrogen or nonsteroidal antiestrogen.

The time course of nuclear translocation of estrogen receptors and the replenishment of cytosolic receptor concentrations in the pituitary gland and hypothalamus of ovariectomized/adrenalectomized rats after the application of a high dose (0.1 mg/animal) of the catecholestrogens, 2-hydroxyethynylestradiol or 4-hydroxyethynylestradiol, was identical to that seen after the application of the monophenolic estrogen 17 alpha-ethynylestradiol. A distinctly different pattern of receptor distribution between these cell compartments was observed after the application of the nonsteroidal antiestrogen monohydroxytamoxifen (ICI 79,280) resulting in a prolonged depletion of cytosolic receptor concentrations. It therefore seems unlikely that the proposed antiestrogenic properties of 2-hydroxyestrogens are the result of a blocking of cytosolic receptor replenishment but may be explained by a reduced intrinsic nuclear activity of estrogen receptors complexed with 2-hydroxyestrogens.

Animals↗
PubMed1983

Application of radioimmunoassay (RIA) for the determination of residues of anabolic sex hormones.

Based on the basic principles of radioimmunoassay (RIA), it can be expected that by using this method, residues of anabolic sex hormones in animal tissues can be quantitated in the ng/g to pg/g range with adequate reliability. This was demonstrated for various endogenous and exogenous steroids as well as for stilbene-estrogens. Using the RIA for DES as a regulatory method allowed the successful control of the misuse of this compound in animal production, especially by examination of excreta. Also, for muscular tissue, an interlaboratory validation study yielded acceptable results. The need for confirmatory methods is stressed.

Adipose Tissue↗
PubMed1981

Effects of repeated fatiguing rhythmical hand work.

In a model work place (hand-grip dynamometer), eleven subjects performed rhythmical hand-grip contractions to exhaustion (frequency 30/min). In each working cycle the contraction and rest phases were distinguished. The work to exhaustion was repeated four times (four working periods with 156-min rest intervals). The tests were performed at 40, 60, 80, 100% MVC. Analysis of Variance showed no difference in the group means (mean values of each working period and load level) for the duration of the contraction or rest phases, the integrated bioelectrical muscle activity (iEMG) of flexors, extensors, brachioradialis (iEMG referred to working cycle and contraction phase) or iEMG of the thenar muscles (referring to the working cycle), or in the duration of the R-R interval in the ECG during comparable periods of the experiments. The endurance times decreased from working period 1-4, and a similar decrease occurred in the force-time product. It may be concluded from these results that 15 min rest is insufficient for adequate recovery from hand-exhaustion exercise.

Adult↗
PubMed1980

Oestrogens, compared to other steroids of testicular origin, in blood plasma of boars.

Oestrogens, testosterone, and 5 alpha-androstenone ('boar taint steroid') were determined in peripheral and spermatic vein blood plasma of boars. Oestrone was the predominant steroid in both the conjugated and the unconjugated fractions of total oestrogens. Concentrations of conjugated oestrogens in peripheral plasma generally are in the range of several nanograms/ml, which is similar to the range of 5 alpha-androstenone and testosterone. Unconjugated total oestrogens are in the lower nanogram-range. These concentrations, however, are still higher than those during the oestrus in sows. Stimulation with hCG led to increased concentrations of peripheral plasma oestrogens, demonstrating their testicular origin. Comparative measurements in spermatic vein plasma and peripheral plasma show that in general the testis has to secrete different amounts of the individual steroid to maintain the appropriate peripheral level. A highly correlated course of all the steroids measured was apparent. This was shown for the diurnal rhythm, the age-related changes and for the increase after application of hCG.

Age Factors↗