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M Kirchgessner

Publications and source records attributed to M Kirchgessner.

At least 343 records · Page 19Linked to original sources
PubMed1976

[Effect of zinc deficiency on the digestibility and utilization of nutrients].

Weaned male rats were used in a metabolic trial to investigate the digestibility of dry matter, crude protein, ash and energy, the energy and N balances and the rates of zinc absorption and zinc retention under conditions of zinc deficiency. 2X8 experimental animals were kept in separate metabolism cages for 6 periods each lasting 5 days. The animals received a semisynthetic zinc-deficient diet (casein + starch + sucrose) containing only 1.0 mg Zn per kg of dry matter (zinc-deficient group fed ad libitum) or plus 49 mg Zn per kg of dry matter (pair-fed control group). The mean intake of dry matter was 2-3 g per day/animal. 2.9 g of food were necessary to produce 1 g of weight increase in the deficient animals and 1.4 g in the controls. The rate of apparent zinc absorption was always clearly negative in the Zn-deficient group. In the control group apparent zinc absorption decreased from 60% to 27% in the course of the trial while zinc retention decreased from 51% to 10%. During zinc deficiency the rates of both faecal and absolute renal Zn excretion were found to be greatly reduced. The proportion of renal zinc excretion relative to total excretion averaged 60% in the experimental group as compared to 17% in the controls. No significant differences were found in the digestibility data of gross energy. Nutrient digestibility (%) was significantly reduced under conditions of Zn deficiency (data for the control group given in brackets): 92,6 (94.0) for dry matter; 93,2 (94.1) for organic matter; 93.3 (96.2) for crude protein and 76.6 (90.8) for crude ash. Similarly, N retention data, in Zn-deficient animals, declined from 30.5% to 14.7%, and metabolizable energy decreased from 88.7% to 85.6%. The differences obtained are not sufficient, however, to account for the clearly increased food requirements observed in zinc-deficient animals. Thus, considerable disturbances have to be assumed to occur in the processes of intermediary nutrient utilization.

Animal Nutritional Physiological Phenomena↗
PubMed1976

[Interaction of nickel with iron, copper and zinc].

Studies were carried out investigating the role of nickel as an essential element in the growth of rats. Reduced levels of iron, copper and zinc were found in the liver, spleen and kidneys during Ni deficiency. These findings could be reproduced in 2 generations of 30-day and 50-day-old rats. Reduced rates of Fe storage during Ni deficiency were, in some cases, even noted of the Fe supply was raised to a level of as high as 100 mg Fe per kg of the diet. This accounted for the diminished haemoglobin values, the reduced erythrocyte count and reduced hematocrite found under conditions of Ni deficiency.

Animals↗
PubMed1976

[Interactions between various transition elements in their effect on pepsin activity].

Kinetic experiments were made with pepsin in the presence of Cu2+ ions and additional Fe2+, Ni2+ or Zn3+ ions as sulphates. As a parameter of the pepsin activity the turnover-rate curves were determined with haemoglobin as a substrate. An important activation of the pepsin was obtained by Cu2+ additions of 5-10(-4) mole/1. When Cu2+ and Fe2+ ions were added to the reaction mixture at the same time, an additive effect of both metal cations was observed. A competitive effect of both metal cations was found in the combination of Cu2+/Ni2+ ions. Zn2+ addition did not influence the activation of pepsin caused by Cu2+ ions.

Animals↗
PubMed1976

[The effect of various pH values on in vitro peptic digestion of proteins in the presence of Cu2 ions].

Studies were carried out to investigate the effect of different pH values on the peptic digestion of soya protein in the presence and in the absence of Cu2+ ions. The studies were performed in vitro at a pH of 2.2 and 3.2, with 2.96 X 10(-5) mole of Cu2+ ions present in 11 of the reaction mixture. The reaction was carried out in a digestion apparatus permitting dialysis of the cleavage products. Different parameters were used as criteria of digestion, viz. the quantity of N contained in the reaction vessel (residue) and in the resulting dialysis products as determined by Kjehldahl microanalysis and automatic amino acid analysis, the proportions of digestion products found in the different molecular ranges after partition of Sephadex G 75 and the composition of amino acids in the cleavage products. From the distribution of the reaction products on the residue and dialysis products and on the different molecular ranges it was found that additions of Cu2+ ions at pH 2.2 produced a considerable inhibition of digestion. With a rise in pH to 3.2 peptic digestion decreased even without the addition of Cu2+. Supplementation of Cu2+ ions produced only a slight additional effect in the molecular range termed "exclusion limit". In the case of the amino acids tyrosine and phenylalanine it was found that an increase in pH changed the composition of peptides within the different molecular ranges. Additions of Cu2+ had no influence on the amino acid composition.

Copper↗
PubMed1976

Radioisotope dilution technique for determination of zinc absorption in vivo.

A radioisotope dilution technique was adapted for determination of the absorbability of dietary zinc. In 16 growing rats given a casein diet with 12.8 mg Zn/kg dry matter, a mean apparent Zn digestibility of 72.4% was observed in a 6-day balance period 9 days after an intramuscular injection of 65Zn-ZnCl2. There was no significant difference in the specific radioactivity of zinc in blood plasma on day 15 and in urine collected from day 9 to day 15 used to assess the fecal excretion of endogenous zinc. Consequently, there was good agreement between the corresponding mean zinc absorbability (94.8 vs. 95.3%) calculated from these data.

Animals↗
PubMed1976

65Zn-labeled tissue zinc for determination of endogenous fecal zinc excretion in growing rats.

Experiments were conducted to study whether selected body tissues other than blood plasma provide suitable endogenous zinc sources to determine endogenous fecal zinc excretion and zinc absorbability by the radioisotope dilution technique. In 16 rats with a mean weight of 172 g on the day of 65Zn injection, the apparent digestibility of zinc (12.8 mg Zn/kg diet dry matter) averaged 72.4 +/- 6.2% during a 6-day balance period starting 9 days postinjection. Based on the specific radioactivity of zinc in plasma after 10 days, two-thirds of the fecal zinc were of endogenous origin and the corresponding zinc absorbability averaged about 91%. Zinc absorbabilities computed on the basis of the specific radioactivity of zinc in the small intestine, pancreas and/or kidneys after 15 days were closely comparable to the mean derived with plasma. Other tissues examined were found less suitable to reflect the specific radioactivity of endogenous fecal zinc.

Animals↗
PubMed1976

[Technic and dosage of zinc injections for studies on metabolic efficiency].

When rats are supplied with zinc by the diet, absorption interferes with the determination of the efficiency of utilization of zinc in metabolism. In studies on the metabolic efficiency of zinc it was therefore attempted to by-pass the step of absorption by i.m. or i.v. injection and, at the same time, to determine the appropriate dosage for these zinc injections. For that reason, young male rats, after 20 days of zinc depletion were injected i.m. or i.v. in five different dosages of ZnCl2 solutions and their gains in live weight were followed. It was found that higher zinc doses given i.v. were lethal to rats, whereas they were tolerated when given i.m. The better metabolic efficiency of zinc, indicated by comparatively higher live weights of the i.v. injected groups, could be seen even at the lower i.v. zinc dosages. Therefore, based on the results of the present experiment, a dose of 0.4 mg zinc is proposed for the i.v. injection to study the metabolic efficiency of zinc in rats.

Animals↗
PubMed1976

[Absorption and metabolic efficiency of iron in nickel deficiency].

Absorption and Metabolic Efficiency of Iron During Ni Deficiency. Ni deficiency leads to reduced iron contents in organs and to greatly reduced Hb levels and erythrocyte counts. Using models it was studied whether this Ni-dependent Fe anemia can be attributed to an impaired absorption of iron or to its metabolic efficiency. An experiment with seven 30-day-old rats from each of two generations were used for this. In Ni deficiency (0.015 ppm dietary nickel) iron absorption was clearly impaired at both 50 ppm and 100 ppm iron in the diet. Compared to the groups given 20 ppm nickel, the amount of iron absorbed fell two-thirds and one-third, respectively. By comparison, the influence on the metabolic efficiency of the iron was relatively small; at high iron supply, however, it was reduced by 8% in the Ni-deficient animals. Therefore, the reduced levels of hemoglobin, erythrocytes and hematocrit must essentially be caused by the impared absorption.

Animals↗