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Biomedical subjects

W Forth

Publications and source records attributed to W Forth.

At least 109 records · Page 6Linked to original sources
PubMed1984

[Drug research in the university and in industry].

Since the beginning of this century, innovations in drug research have increasingly emanated from industrial laboratories rather than from universities. Despite this fact, the significance of universities for the innovation capacity of society must not be underrated. In the Federal Republic of Germany, however, the present conditions for successful cooperation between industry and universities are revealing a diverging tendency in view of this--admittedly utopian--optimum.

Drug Industry↗
PubMed1984

Effect of lidocaine on in vitro absorption of glucose in jejunal and ileal segments of the rat.

The influence of lidocaine on the intestinal glucose absorption was investigated on Tyrode-perfused isolated intestinal segments of the rat. In ileal segments the transmural transfer of glucose decreased with increasing lidocaine concentration (5 X 10(-9) -2 X 10(-4) mol/l), whereas the water movement was unaffected. No inhibitory effect on glucose and water absorption was observed in the proximal jejunum.

Animals↗
PubMed1984

Effect of acute and subchronic exposure to cadmium on the retention of iron in rats.

The influence of cadmium on the retention of a single dose of iron after acute and subchronic treatment with cadmium was studied in normal rats. Additionally the results were compared with iron retention in unexposed iron-deficient animals. Test solutions contained iron and cadmium in various molar ratios (Fe:Cd = 1:0, 1:0.5, 1:1, 1:2 mumol/kg body weight). In acute experiments iron retention of normal unexposed rats was decreased in a dose-dependent manner by cadmium. In subchronic studies the diets fed during the treatment period contained iron (28 ppm) and cadmium (28, 56, 112 ppm) in the same molar ratios as did the test solutions. After 4 weeks of feeding a cadmium-fortified diet, the retention of a single dose of 59Fe was increased in all pretreated animals. Iron retention of the cadmium-fed rats was reduced, however, only if cadmium and iron were administered simultaneously. Cadmium appears to compete with iron at the iron transfer system. Acute or subchronic exposure to cadmium did not appear to influence the capability of the intestine to adapt absorption of iron to the increased requirement of the organism or to the utilization of iron for hemoglobin synthesis.

Anemia, Hypochromic↗
PubMed1984

On the absorption of divalent and trivalent iron in living rats.

For therapeutic purposes ferric and ferrous iron seems to be evaluated in favour of the latter, despite of the fact that at least in animal experiments no difference was observed as far as the bioavailability of either valency state of iron is concerned; prerequisite is that iron has been administered in ionized form. These results have been proven actually by the studies on normal and iron-deficient rats in vivo fed by stomach tube with radioactively labeled 59Fe-(FeSO4), 59Fe-(FeCl3), and the organic complex of 59Fe-Fe(III)-polymaltose). At least in iron-deficient rats the utilization of iron administered in the form of the organic complex was little less than that obtained after having fed FeSO4. Besides the retention of 59Fe-radioactivity 6 days later after the administration also the uptake of 59Fe-radioactivity into erythrocytes and liver has been measured.

Absorption↗
PubMed1983

The influence of tin, nickel, and cadmium on the intestinal absorption of iron.

The influence of increasing doses of cadmium, nickel, and tin on the net absorption of fluid as well as upon the absorption of 59Fe, administered as 59Fe-(FeSO4), from tied-off jejunal segments of male Sprague-Dawley rats were investigated. The three metals examined decreased the net absorption of fluid from the jejunal segments progressively with increasing metal doses. Cadmium was the most potent inhibitor of fluid absorption followed by tin and nickel. Tin, cadmium, and nickel diminished the absorption of 59Fe with increasing doses. The content of 59Fe of the jejunal tissue was not statistically significantly influenced by nickel, whereas tin as well as cadmium diminished the content of 59Fe significantly. Cadmium decreased the content of 59Fe to a greater extent than tin. Obviously nickel influences the rate-limiting process of iron absorption, i.e., the transfer of iron from mucosal cells into blood. Tin and cadmium appear to interact with the process of iron uptake on the surface within the mucosal cells as well as with the iron-releasing process at the contraluminal side. Cadmium as compared with tin is a stronger inhibitor for the processes involved in iron absorption.

Animals↗
PubMed1982

The excretion of thallium (I)-ions into the gastrointestinal tract in situ of rats.

1. The excretion of Tl+-ions from blood into the lumen was investigated on the stomach and on segments of jejunum, ileum, colon ascendens, and colon descendens in situ of anesthetized rats using the pendular perfusion technique. The kidneys of the rats were tied-off. Tl+-ions were administered i.v. at the beginning of the experiments as 204Tl-(Tl2SO4). The amount of 204Tl-labeled Tl+-ions in the perfusion fluid of the gastrointestinal sections was calculated from the 204Tl concentration and the fluid volume. 2. Excretory activity for Tl+-ions is highest in the the jejunum; it is followed by the colon ascendens. The ileum and the colon descendens show nearly equal excretory activity which is just half of that measured in the jejunum. The amount of Tl+-ions excreted into the stomach is negligible. 3. At the end of the experiment in the perfusion fluid of all segments of the intestine the concentration of 204Tl is statistically significantly higher than that in plasma. 4. In jejunal and colonic (descendens) segments the amount of Tl+-ions excreted increases with increasing i.v. doses tested from 2 x 10(-8) up to 2 x 10(-6) moles/kg body weight.

Animals↗
PubMed1981

Determination of transferrin-like immunoreactivity in the mucosal homogenate of the duodenum, jejunum, and ileum of normal and iron deficient rats.

1. In intestinal mucosal tissue a transferrin-like immunoreactivity (TLIR) was determined after loading with 59Fe-(FeCl3) in vivo. The scraped-off mucosal tissue was homogenized and centrifuged at 100 000 X g. The supernatant was fractionated chromatographically. The TLIR was determined by the Mancini-test. 2. Extrapolated to infinite dilutions of the homogenate the following contents of the TLIR were calculated per cm of the intestinal segment: 28, 20, and 13, microgram/cm in the duodenum, jejunum, and ileum of iron-deficient animals and 15, 14, and 12 microgram/cm in the corresponding intestinal segments of normal rats, respectively. 3. The content of TLIR was compared with the iron uptake of the mucosal tissue from the intestinal lumen during absorption. An "iron turnover number" of 1.6 +/- 0.2 iron atoms per min during the absorption in duodenal and jejunal segments and of 0.5 +/- 0.1 in ileal segments of either iron-deficient and normal animals was calculated for the mucosal transferrin represented by the TLIR.

Anemia, Hypochromic↗
PubMed1981

Influence of fucoidan on the intestinal absorption of iron, cobalt, manganese and zinc in rats.

Fucoidan was extracted from the seaweed Ascophyllum nodosum with boiling water and purified by repeated precipitation steps. Increasing doses of fucoidan (1.2--200 mg) were injected together with 360 nmol 59Fe-(FeCl3) or 60Co-(CoCl2) into tied-off jejunal segments of two groups of rats fed either a normal (160 mg Fe/kg) or a low iron diet (5 mg/kg). Fucoidan together with 360 nmol 54Mn-(MnCl2) or 65Zn-(ZnCl2) was administered in the same manner in rats fed a normal diet only. Fucoidan administered in doses above 30 mg decreased the absorption of iron, cobalt, manganese and zinc in normal rats, and the absorption of iron and cobalt in iron-deficient rats. This inhibitory effect of fucoidan on the absorption of heavy metals is apparently the consequence of the formation of metal complexes which are poorly absorbed from the intestinal lumen.

Animals↗