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Biomedical subjects

B Koch

Publications and source records attributed to B Koch.

At least 217 records · Page 12Linked to original sources
PubMed1979

Effects of adrenalectomy and hypercorticism on the ACTH content of the anterior and posterior pituitary in rats with inherited diabetes insipidus (Brattleboro strain).

The effects of adrenalectomy (Adx) and hypercorticism on the ACTH content in the anterior (AH) and the neurointermediate lobe (NIL) of the pituitary in Long Evans (+/+), heterozygous (+/DI) and homozygous (DI/DI) Brattleboro rats were determined using dispersed adrenal cells bioassay. Adx decreased the NIL-ACTH content in +/DI and DI/DI rats and left it unchanged in the +/+ rats. Adx increased the AH-ACTH content in the three groups. Hypercorticism had a delayed decreasing effect both in the AH and in the NIL in all rats, with one exception for the NIL in DI/DI rats. Conversely to what appeared in Wistar rats, in Long Evans and Brattleboro rats the corticosterone administered in drinking water was unable to reduce the increase in AH-ACTH activity. These data suggest that Brattleboro, and, to a lesser extent, Long Evans rats from which the former are derived present some particularities in the regulation of their corticotropic function at the AH and the NIL level. We also observed that NaCl (0.9%) added to drinking water and hypercorticism are two factors able to increase diabetes insipidus in homozygous rats without modifying the water intake in Long Evans and heterozygous rats.

Adrenal Glands↗
PubMed1979

Relationship between ACTH secretion and corticoid binding to specific receptors in perifused adenohypophyses.

This study reports on the kinetics of glucocorticoid-induced inhibition of ACTH release, together with steroid binding to specific pituitary receptors. It was shown that corticosterone (CORT) inhibited ACTH output provoked by either corticotropin-releasing factor (CRF) extracts or dbcAMP, in a manner which was both dose- and time-dependent. A close correlation appeared to exist between the degree of ACTH blockade and the percentage of filled steroid-binding sites. However, exposure of hypophyses to CORT for a critical period of time was a prerequisite for such a relationship to develop. Furthermore, it was found that dexamethasone (DEX) was more potent than CORT in inhibiting ACTH secretion and, in addition, bound to a greater extent to nuclei of pituitary cells. These data suggest the existence of a close correlation between occupancy of pituitary glucocorticoid receptors and modulation of ACTH secretion.

Adrenocorticotropic Hormone↗
PubMed1979

In vitro regulation of ACTH release from neurointermediate lobe of rat hypophysis. II. Effect of neurotransmitters.

The effect of various neurotransmitters on adrenocorticitropic hormone (ACTH) release from superfused neurointermediate lobes of rat hypophysis (NIL) was investigated. Acetylcholine, serotonin, and histamine were shown to have no significant effect on the spontaneous release of ACTH. In contrast, dopamine (DA) and noradrenaline (NA) stimulated NIL ACTH release in a dose-dependent manner. The stimulating effect of DA was mimicked by apomorphine and inhibited by haloperidol, whereas that of NA was abolished by phentolamine. In a comparative study, none of these neurotransmitters is shown to have any significant stimulating effect on ACTH release from superfused anterior lobes. It is concluded that the ACTH release from NIL might be controlled, at least in part, by catecholaminergic innervation.

Acetylcholine↗
PubMed1979

Renal transplantation in insulin-treated diabetics.

In our view, renal transplantation in the uremic diabetic patient is justified. Recipients should be selected with caution. Patients with both loss of vision and heart disease will only rarely benefit from renal transplantation. Living related donor should be preferred if possible.

Adult↗
PubMed1978

In vitro regulation of ACTH release from neurointermediate lobe of rat hypophysis. I. Effect of crude hypothalamic extracts.

Using incubated glands, we showed that cerebral cortex and liver extracts (CCE and LE) stimulated ACTH release from neurointermediate lobe (NIL) of hypophysis as well as hypothalmus extract (HE) did. Moreover, the HE-induced ACTH release was much smaller for the NIL (1.9 X basal level) than for the anterior lobe (AL; 13.7 x basal level). Thus, under these conditions, HE seemed to have no specific effect on NIL ACTH release. Using superfused glands, we showed: (a) that both spontaneous and HE-induced ACTH release decreased during superfusion; (b) that using this system, a specific stimulatory effect on HE on NIL was observed. In contrast to HE, CCE and LE had only a small effect on NIL ACTH release (always less than 20% of that caused by HE) which could be considered as a nonspecific response; (c) that trypsin suppressed the stimulating effect on HE as well on NIL as on AL; and (d) that arginine antidiuretic hormone (ADH) was not responsible for the stimulating effect of HE on NIL ACTH release, because synthetic ADH had no effect and HE containing ADH (from normal rats) or HE containing no ADH (from Brattleboro rats or from immunoneutralization of ADH in normal HE) had the same effect. From these results, we can conclude that HE contain a peptidic factor different from ADH which is able to stimulate in vitro release of ACTH from the NIL.

Adrenocorticotropic Hormone↗
PubMed1978

Inverse effects of corticosterone and thyroxine on glucocorticoid binding sites in the anterior pituitary gland.

The aim of this study was to determine whether pituitary glucocorticoid binding sites are under hormonal control. It was shown that corticosterone and thyroxine exerted antagonistic effects on both the transcortin-like component and true receptor present in the hypophysis: thyroid hormones, in contrast to glucocorticoids which exhibited opposite influence, increased maximum binding without affecting significantly the apparent association constant. Thus, it seems that the concentration of glucocorticoid binding sites is regulated by the glucocorticoid ligands, as well as by a different hormone. Moreover, a striking parallelism was found between plasma transcortin and pituitary transcotin-like capacity, argueing in favour of a plasma origin for this pituitary binder.

Adrenalectomy↗
PubMed1978

Specific interaction of corticosteroids with binding sites in the plasma membranes of the rat anterior pituitary gland.

The binding of glucocorticoids to a crude fraction of rat pituitary plasma membranes and to solubilized membrane proteins was measured. The binding characteristics were similar to those exhibited by transcortin: radioactive corticosterone was bound to a greater extent than radioactive dexamethasone and labelled corticosterone, but not labelled dexamethasone, was displaced by unlabelled corticosterone, deoxycorticosterone and progesterone. A Scatchard plot of the binding data revealed the presence of a binding material with a dissociation constant of about 3.2 nmol/l, which sedimented at 4S after sucrose density-gradient centrifugation. It was found that the number of binding sites was inversely related to the concentration of corticosterone in the circulation and was increased after long-term adrenalectomy. These data suggest that a material similar to transcortin is complexed to the plasma membrane of rat pituitary cells.

Adrenalectomy↗
PubMed1978

Brachial plexus palsy in neonates and children.

In 135 children with obstetrical palsy, clinical and electrodiagnostic studies on inital and serial evaluation aided in designing a conservative treatment program. Prevention of contractures, maintenance of muscle strength and reinforcing the child's awareness of the affected limb were predicated on the limiting factors of permanent denervation and agnosia. Instability of the scapula, scapulohumeral adhesions and elbow flexion with loss of active supination defy conventional range of motion exercises. Forced passive supination of the elbow may actually compound the problem of radial head dislocation and ulnar bowing. Because of the young age of most of the patients, only 7 have had orthopedic intervention. Rotational osteotomy of the humerus and transfer of intact muscles seem to improve function. Prior to selection of muscles for transfer, electromyography is advised. Later surgical treatment of the shoulder and elbow seems to improve cosmesis but not function. Of the 135 children, 70% had mild residua, 22% showed moderate impairment and 8% had severe deficit.

Brachial Plexus↗
PubMed1977

[Reduced radiation sensitivity of hyperthyroid goiter with endocrine ophthalmopathy (author's transl)].

The therapeutic success of fractionated radioiodine treatment of hyperthyroid patients with and without endocrine ophthalmopathy is examined. To achieve a stable euthyroid metabolism, patients with endocrine ophthalmopathy generally need a greater number of treatments with a necessarily higher total dose of radioiodine and longer duration of treatment than hyperthyroid patients without endocrine ophthalmopathy. The average age, the average uptake of 131l and the serum concentration of free T4 were comparable in both groups of patients. A struma nodosa was more frequently found in the group of hyperthyroid patients with endocrine ophthalmopathy than in hyperthyroid patients without exophthalmus.

Dose-Response Relationship, Radiation↗
PubMed1977

Comparative in vitro studies on corticotropin releasing activity of vasopressin and hypothalamic median eminence extract.

The in vitro corticotropic releasing effects of vasopressin (VP) and hypothalamic median eminence (HME) extract were compared as a function of their concentration and preincubation and incubation times. Whereas HME extract augmented the ACTH secretion from non-preincubated adenohypophyses, VP released corticotropin from the pituitaries only after a 2 h preincubation period. The disappearance of endogenous VP during the preincubation time rendered the gland responsive. The maximal stimulation of ACTH secretion by VP was markedly less than that induced by HME extract. The results suggest the presence of VP receptor sites in the anterior pituitary (AP) which are probably different from the receptor sites of the hypothalamic corticotropin releasing factor (CRF).

Adrenocorticotropic Hormone↗
PubMed1976

Heterogeneity of pituitary glucocorticoid binding evidence for a transcortin-like compound.

Scatchard analysis, as well as sucrose gradient centrifugation demonstrate that at least two classes of specific glucocorticoid binding sites occur in the adenohypophysis. One, exhibited high affinity for both corticosterone and dexamethasone (receptor D), while the other bound only corticosterone. The latter binder revealed physico-chemical properties closely similar to those of plasma transcortin, but was shown not to be due to simple blood contamination of cytosol. This transcortin-like (TL) component, however, seemed to be carried over from plasma, since the concentration of pituitary binding sites strikingly paralleled physiological variations of plasma transcortin. Furthermore, experiments carried out with isolated pituitary cells suggested an intracellular location of that binder, although sticking to the cell membrane cannot be excluded. Finally, it was shown that the TL compound was unable, unlike the receptor D, to transfer glucocorticoids into the nuclei. One of its possible roles could be to modulate the interaction between steroids and compound D.

Adrenal Glands↗