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Biomedical subjects

W Engelhardt

Publications and source records attributed to W Engelhardt.

At least 91 records · Page 5Linked to original sources
PubMed1984

Effects of highly selective vagotomy on small intestinal calcium transport in the rat.

In parathyroid-intact and parathyroidectomized rats we studied the influence of highly selective vagotomy (HSV) on net absorption and bidirectional (lumen-to-plasma, LP; plasma-to-lumen, PL) calcium (Ca) fluxes in the duodenum and ileum. In parathyroid-intact rats, Ca fluxes in the duodenum and ileum are not significantly altered by HSV. Nevertheless, net absorption is increased in the duodenum and decreased in the ileum. In parathyroidectomized rats duodenal LP flux is reduced and ileal PL flux is increased, by HSV, with the result that there is a decrease in the net absorption in both intestinal segments. It is suggested that (1) in intact rats, the influence of HSV on the net absorption of Ca is different in the duodenum and the ileum; (2) after prior parathyroidectomy, HSV is potentially harmful to the Ca balance of the body, and (3) the mineral metabolic effects of HSV have so far not been adequately studied.

Animals↗
PubMed1983

The role of parathyroid hormone and calcitonin in magnesium absorption in the rat small intestine.

We studied duodenal and ileal magnesium (Mg) absorption in intact, parathyroidectomized (PTX), thyroid-(TX) and thyroparathyroidectomized (TPTX) rats with iodine hormones replaced, and, additionally, in PTX rats receiving bovine parathyroid hormone 1-34 and 1,25-dihydroxyvitamin D3, respectively. Mg absorption was reduced after PTX and TPTX in the duodenum, but not in the ileum, whereas TX had no influence on duodenal or ileal Mg absorption. Both bovine parathyroid hormone 1-34 and 1,25-dihydroxyvitamin D3 increased Mg absorption in the duodenum and the ileum in PTX rats.

Animals↗
PubMed1983

Influence of exogenous glucagon on gastric acid secretion, mucosal blood flow, and stress ulcers in the rat: dose-response results under non-stress conditions and immobilization stress.

In non-stressed rats and rats stressed by immobilization, gastric secretion (acid, pepsin), mucosal blood flow (MBF), stress ulcers as well as glucose, insulin, and glucagon in blood were studied during 8 h, with and without additional infusion of exogenous glucagon (0.2, 1.4, 9.8 micrograms/kg/h). Metabolic clearance of glucagon and the disappearance half-time of exogenous glucagon from blood do not differ during zero stress and stress, a fact that favors the assumption of hypersecretion of glucagon as the cause of stress hyperglucagonemia. During stress alone acid secretion (volume, acidity) and MBF are lower than during zero stress; pepsin remains unchanged. Under zero stress condition additionally administered glucagon inhibits pepsin and MBF, but not acid secretion, in a dose-dependent manner. The ulcer index increased without changing the severity of ulcers. During stress the intermediate and highest glucagon doses stimulate MBF and pepsin secretion, other variables remaining unchanged. It is concluded that glucagon effects on functions of the gastric mucosa in the rat vary fundamentally, depending upon the environmental conditions.

Animals↗
PubMed1983

Experimental studies on pancreatic duct occlusion with prolamine.

The effect of the occlusion of the pancreatic duct system with prolamine (Ethibloc) has been studied in animal experiments with dogs and mini-pigs. The solution becomes solid in the duct system and becomes disintegrated again within 11 days. This time, however, is sufficient to keep a high-grade atrophy of the exocrine parenchyma. With this method one doesn't risk the provocation of an acute pancreatitis. The endocrine function of the atrophied glands is satisfactory, no animal became diabetic. The basal jugular vein insulin shows no difference to that of the control group, but nevertheless the mean whole pancreas hormone content is reduced for insulin and somatostatin, but not for glucagon.

Animals↗
PubMed1983

[Autoradiographic studies on the protective effect of mesna in the urinary bladder mucosa of the rat during administration of cyclophosphamide (preliminary communication)].

Cyclophosphamide (100 mg/kg i.p.) produces severe bladder lesions in rats and induces an intense regeneration of the urothelium which can be followed up by 3H-thymidine incorporation. Simultaneously administered mesna (100 mg/kg i.v.) prevents these bladder lesions and no increased regeneration with 3H-thymidine incorporation can be observed.

Animals↗
PubMed1983

Mineral metabolism and vitamin D status before and up to five years following highly selective vagotomy in duodenal ulcer patients.

The influence of highly selective vagotomy (HSV) upon mineral metabolism was investigated in patients with duodenal ulcer (DU). Data obtained before HSV were compared with those from healthy control subjects and, additionally, with data from pre- and post-HSV observations. In DU the function of the parathyroid glands is unsettled because of decreased renal phosphate threshold, normal serum parathyroid hormone and decreased nephrogenous urinary cAMP. HSV decreases the phosphate threshold further, but does not change parathyroid hormone, calcitonin, or nephrogenous cAMP. Conversely, besides hypergastrinemia, HSV accounts for a decrease in total calcium in serum in the presence of an increase of the intestinal calcium absorption, while the bone mineral content is stable up to 5 years following HSV. Moreover, HSV normalizes the decreased serum concentration of 25-hydroxyvitamin D found pre-operatively in DU, while that of 24,25-dihydroxyvitamin D, known to be effective upon bone and gut, remains unaltered. A classification according to pre-operative gastric acid secretion (normo- and hypersecretors) does not provide further insights into variables of mineral metabolism encountered in DU pre- and post-HSV.

Adult↗
PubMed1982

Calcium absorption in the rat as influenced by highly selective vagotomy with special regard to endogenous gastrin.

The effect of HSV (controls: sham), which induces hypergastrinemia, on duodenal Ca absorption was studied in "intact", TPTX, PTX, and TX rats. Ca absorption was estimated by an in vivo loop technique. As this technique increased serum gastrin by the duodenal Ca load, gastrin was also measured in rats not subjected to evaluation of Ca absorption. Following vagotomy gastrin rose significantly in "intact" as well as in TPTX, PTX, and TX rats. Further, intraduodenal Ca increased gastrin both after sham and vagotomy. However, gastrin in vagotomized rats was significantly higher than in sham rats, too. Although duodenal Ca absorption was not altered by vagotomy in "intact" and in TX rats, it was significantly lowered in vagotomized TPTX and PTX rats. Pretreatment of TPTX rats by pentagastrin for 10 days or immediately preceding experiments did not change Ca absorption. In addition, serum parathyroid hormone was unchanged by vagotomy in "intact" rats as compared to sham controls. We conclude that (1) vagotomy does not influence the rate of duodenal Ca absorption in "intact" rats, (2) Ca absorption is lower after vagotomy only in the absence of parathyroid glands, and (3) this vagotomy effect is not mimicked by exogenous pentagastrin and therefore appears unrelated to endogenous postvagotomy gastrinemia.

Animals↗
PubMed1982

Determination of urinary oxalate by isotachophoresis practical improvement and critical evaluation.

We developed an electronic control unit for the determination of oxalate in urine by isotachophoresis with the LKB 2127 Tachophor. It permits a considerable reduction of the time required for analysis. Measurements were carried out in samples of untreated urine using different leading electrolytes and standardization procedures. Determination of oxalate can be thus achieved within 25 min, whereof the manpower expenditure is about 5 min. In the range of 1.0-0.1 mmol/l urinary oxalate can be determined with a coefficient of variation of 4-6%. The detection limit of the method is about 0.04 mmol/l.

Cations↗
PubMed1982

Stress-induced reduction of gastric acid in the rat is not associated with increased tissue somatostatin.

In zero, mildly and severely stressed rats, gastric acid secretion, aortal and portal venous gastrin, venous glucagon and somatostatin in gastric, duodenal mucosa and in pancreas were examined. Serum gastrin and gastric acid secretion are reduced markedly by both kinds of stress, whereas plasma glucagon rises steadily with stress. As somatostatin in the tissues of stressed rats is not different from unstressed controls, gastrin and gastric acid reduction may not be attributed to an endocrine or paracrine action of somatostatin.

Animals↗
PubMed1981

Gastric secretion, mucosal erosions and porto-systemic gastrin gradients as influenced by different degrees of stress in the rat.

Gastric fistula rats (n = 79) were either left as unstressed (fistula closed) controls or gastric secretion, microcirculation (MBF), mucosal stress ulcers were studied in secretory rats subjected to zero (= freely movements allowed), mild, severe restraint stress for 8 h. In all rats gastrin in portal vein and aorta was measured in addition after discontinuation of either protocol. Acid secretion and MBF are progressively reduced by increasing stress. Pepsin and sodium are elevated with severe, acid concentration with mild stress. Pepsin and sodium are elevated with severe, acid concentration with mild stress. Serum gastrin (controls - aorta 53+/- SEM 5, portal vein 73 +/- 9 pg/ml) rises sharply in portal and systemic blood with institution of acid diversion via the outside (zero stress - 136 +/- 21, 398 +/- 98 pg/ml), but declines with increasing stress (severe stress - 82 +/- 16, 101 +/- 27 pg/ml) despite otherwise identical experimental conditions. It is concluded that (1) acid secretion rate and MBF are lowered by stress, but stress ulcers are associated with either increased acidity (mild stress) or peptic activity (severe stress) of gastric juice in the absence of elevated gastrin, (2) enhanced sodium fluxes via gastric lumen and lower acid suggest disruption if mucosal barrier by severe stress, and (3) restraint stress ulcers may be the expression of a combination of disturbances, mainly of metabolic and endocrine nature.

Animals↗
PubMed1981

Development of a sensitive somatostatin radioimmunoassay and its application to plasma of stressed and non-stressed rats.

A sensitive somatostatin radioimmunoassay was developed and immunoreactive somatostatin was measured in plasma of different vessels of stressed and non-stressed rats. Detection limit of the assay is 4 pg/ml. Serial dilutions of rat plasma run parallel to the standard curve. On gel chromatography of rat plasma immunoreactive somatostatin elutes at the position of synthetic somatostatin. Immunoreactive somatostatin in plasma of non-stressed rats is (mean +/- 1 SEM) 369 +/- 58, 244 +/- 66, 273 +/- 61, 260 +/- 44, 359 +/- 80 pg/ml in aorta abdominalis, vena cava, vena renalis, vena jugularis, vena porta respectively. After stress mean immunoreactive somatostatin was higher in plasma of all vessels, in aorta abdominalis (p less than 0.01), vena renalis and vena porta about 50 per cent, in vena jugularis and vena cava about 90 per cent (p less than 0.002). We conclude that under conditions like stress somatostatin circulates in increased amounts and perhaps reaches organs distant from documented sources.

Animals↗