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Biomedical subjects

R Thun

Publications and source records attributed to R Thun.

11 recordsLinked to original sources
PubMed1979

Hypocalcemia during restraint stress in rats. Indication that gastric ulcer prophylaxis by exogenous calcium interferes with calcitonin release.

The influence of restraint stress on serum calcium (Ca) and phosphate was studied in normal and thyroidectomized rats. In addition the response of gastric stress ulcer index, blood gastrin and glucagon to exogenous Ca was investigated. In intact as well as in thyroidectomized animals serum total, ionised and previously injected radioactive Ca decrease during an 8h stress period, whereas inorganic phosphate increases. Together with a constant specific activity these findings are consistent with hypoparathyroidism and calcitonin independent hypocalcemia during stress. Intragastric infusion of 45 mg/kg Ca-gluconate per 8h proves to be a potent anti-stress ulcer regimen in intact and neck-sham operated, but not in thyroidectomized rats without and with additional adrenal demedullation. Gastrin and glucagon were not correlated with calcemia during either stress alone or stress combined with intragastric Ca infusion. It is suggested that the development of gastric stress ulcerations can be prevented by a Ca-mediated release of endogenous calcitonin.

Adrenal Medulla↗
PubMed1978

[Evaluation of renal cyclic adenosine monophosphate, serum parathyroid hormone and phosphate reabsorption in recurrent calcium urolithiasis, healthy controls and hyperparathyroidism (author's transl)].

In three groups (n = 12 each) of male controls (22--43 years), patients with recurring calcium urolithiasis (21--36 years) and hyperparathyroidism (HPT; 17--71 years) proven by surgery renal cyclic adenosine monophosphate (RcAMP), fractional tubular phosphate reabsorption and serum parathyroid hormone (PTH) were measured during endogenous creatinine clearance. RcAMP (muMol/g creatinine) was: controls 1.48 +/- SEM 0.27; stone formers 2.037 +/- 0.343 (not significantly different); HPT 6.234 +/- 0.454 (p less than 0.001). There is no overlap between HPT and controls. Phosphate reabsorption is least in HPT (0.84 +/- 0.015), higher in controls (0.924 +/- 0.004) and stone formers (0.941 +/- 0.007). All differences are statistically significant. Under the conditions selected (moderate hydration of individuals) Serum PHT (pg-equiv/ml) is lowest in stome formers (less than 100--339), higher in controls (less than 100--933) and HPT (400--1150). there is no overlap in PHT between the former and the latter group but a marked one between controls and HPT. For clinical purposes the resulting diagnostic uncertainty in a given patient can be overcome by additional determinations of RcAMP and ionised serum calcium: when referring to serum PTH HPT patients fall outside, RCU patients within 2 standard deviations of either parameter in control subjects. This procedure presently appears superior to those proposed in the past (urinary cAMP etc.) but requires confirmation in larger patient populations. Moreover, since HPT prevails in middle and upper age decades, their RcAMP values and those of RCU patients should be related to a range seen in closely age- and sex-matched controls.

Adult↗
PubMed1977

[Evaluation of H2 receptor blockade with metiamide in stress ulcers in rats].

Restrain stress in rats inhibits gastric secretion and microcirculation. Secretion is further inhibited by metiamide, but mucosal blood flow is restored to normal. During stress the ulcer incidence is high, lower with prophylactic administration of metiamide and least with the latter and preserved gastroduodenal acid transit. No therapeutic metiamide effect can be detected.

Aminopyrine↗
PubMed1977

Induction of estrus and ovulation in the bitch, using exogenous gonadotropins.

The capability of pregnant mare serum (PMS) and human chorionic gonadotropin (HCG) to induce estrus and ovulation was tested in mature, anestrous bitches. The PMS was given for 10 consecutive days in 1 of 3 regimens: 500 IU/day (experiment 1), 250 IU/day (experiment 2), or 20 IU/kg/day (experiment 3). The HCG was given as a single 500-IU dose on experimental day 10. Controls were given saline solution. Vaginal smears were collected on days 1, 3, 5, 7, 9, and 12 by jugular venipuncture, and the plasma was assayed for progesterone concentration by radioimmunoassay. On day 13, the bitches were euthanatized, ova were flushed from the uterine tubes (oviducts), and the ovaries were collected and prepared for microscopic examination. Fourteen of 25 bitches treated with PMS and HCG showed estrus and ovulated. Proestrus (vaginal bleeding) commenced between experimental days 7 and 10. Estrus commenced on day 9 or 10. Progesterone increased from approximately 1 ng/ml on day 1 to more than 6 ng/ml on day 12. Numbers of ovulation sites on both ovaries were 4.7 +/- 1.1 and 4.6 +/- 0.5 (mean +/- SEM) in those given the daily doses of 500 and 250 IU of PMS and 9.8 +/- 1.5 in experiment 3 bitches. Eleven hormone-treated dogs and 7 saline-treated dogs did not show any detectable response. Neither cystic nor unovulated, luteinized follicles appeared on the ovaries.

Animals↗
PubMed1977

Anti-stress ulcer and anti-secretory effect of somatostatin in rats -- failure to suppress serum gastrin.

In rats the influence of arresting free motions (= controls; mild stress) and of restraint (= severe stress) without and with additional somatostatin (SRIF) on gastric secretion, mucosal microcirculation and stress ulcer formation was studied. Severe stress alone reduces volume, acid and pepsin secretion, acid concentration, aminopyrine clearance and ratio. The ulcer index is elevated. Under both conditions SRIF inhibits in a dose-dependent manner volume and acid secretion, and ulcer incidence is lower. The interaction between severe stress and the antiulcer component of SRIF is characterized as non-competitive. Under these conditions and a continuous infusion of SRIF (10.0 microgram/kg.h over 8 h) acid concentration, acid and pepsin secretion fall subtotally, ulcer index to 50 percent of vehicle (saline) treated rats, if gastric fistula drains juice outside stomach. Microcirculation and serum gastrin are unchanged. In animals with closed fistula ulcer index is reduced by 85 percent, average gastrin again is unchanged. It is concluded that stress ulcers develop at a low secretory and microcirculatory state of gastric mucosa. The prophylactic effect of SRIF results from direct inhibition of parietal and chief cells and additional yet unknown factors.

Animals↗