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Biomedical subjects

E Weigand

Publications and source records attributed to E Weigand.

At least 19 recordsLinked to original sources
PubMed1998

Functional diversity of synaptic AMPA/KA receptors from rat as revealed by subtype-specific antagonists.

Subtype-specific pharmacological compounds represent important tools to identify the molecular components of synaptically activated glutamate receptors in central neurones. Here, we utilized a collection of subtype-specific antagonists and modulators to investigate the functional profile of glutamate receptors in identified synapses in thin slices of the cerebellum, hippocampus and brain stem. During whole-cell patch-clamp recordings alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate/kainate (AMPA/KA) receptor-mediated synaptic currents (EPSCs) in cerebellar Purkinje cells were (i) prolonged by 100 microM cyclothiazide, (ii) not significantly changed after preincubation in 10 microM concanavalin A, (iii) not affected by 1 microM Evans Blue or polyamine toxin analogue N-(4-hydroxyphenylpropanolyl)-spermine (NHPPS), but (iv) significantly reduced by high (> or = 100 microM) concentrations of Evans Blue. These pharmacological properties were distinct from those observed in hippocampal granule cells and brain stem interneurones and markedly different from those of recombinant glutamate receptor channels GluR1-GluR6 previously investigated in heterologous expression systems.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1992

Absorption, endogenous excretion, and balance of zinc in growing rats on diets with various sugars replacing starch.

The effect of partially replacing starch for various sugars on the apparent and true absorption, endogenous excretion, and balance of zinc was investigated in a study with growing rats. Six groups of five or six animals with an initial live weight of 39.4 +/- 2.7 g were fed diets that had the same Zn content (22 mg/kg), but differed in the sugar content: 1. Starch only (56%); 2. Glucose (15%); 3. Fructose (15%); 4. Sucrose (30%); 5. Galactose (15%); and 6. Lactose (30%). At the start of a 15-d fecal and urinary collection period, each animal was given an intramuscular injection of 380 kBq 65Zn for estimating endogenous Zn excretion by isotope dilution. The ratio of the specific activity of fecal Zn (after 12 d) to that of urinary Zn (after 9 d) was applied to reflect the ratio of endogenous to total fecal Zn collected from day 10 to 15. This ratio averaged 0.59, without significant differences among treatments. For this period, apparent and true absorption averaged 87.1 and 94.7% of Zn intake, respectively, and did not significantly differ among diets. Urinary excretion of 65Zn and of stable zinc by the galactose-fed rats was markedly higher than that by the other animals. Their Zn balance was, per unit weight gain, comparable with that of the other groups (30.7 vs 28.2 to 30.2 micrograms/g).

Absorption↗
PubMed1992

Excretion and distribution of injected radiozinc in rats as influenced by the type of carbohydrate.

The aim of this study was to investigate the effect of different dietary sugars on Zn status by measuring the excretion and body distribution of intramuscularly injected zinc-65 in growing rats. Thirty-two weanling rats (39.4 +/- 2.7 g) were allotted to six diets in which starch (56%) was partially substituted for glucose (15%), fructose (15%), sucrose (30%), galactose (15%) or lactose (30%). Diets uniformly supplied 22 mg/kg (dry matter) of Zn. Three days after the start of the dietary regimen each rat was injected with 40 micrograms Zn, labelled with 380 kBq 65Zn, in saline solution. Feces and urine were collected for 15 days; thereafter 65Zn distribution in the liver, pancreas, kidneys, gastrointestinal tract and residual carcass was assessed. Fecal 65Zn excretion was not significantly influenced by the diets, although the gastrointestinal tract of the galactose- and lactose-fed animals contained more 65Zn than did those fed the other diets. 65Zn in the urine and kidneys of the galactose-fed rats was markedly increased as compared with the other groups. Dietary carbohydrate source did not materially affect concentrations of stable zinc in the liver, kidneys, pancreas and residual carcass.

Animals↗
PubMed1991

[The postnatal iron status of trotter foals].

The postnatal iron status of 20 trotter foals (7 female, 13 male) was studied by analyzing different parameters in blood drawn on the day of birth, and 14 +/- 2 and 28 +/- 2 days later. Hemoglobin hematocrit, plasma iron and transferrin saturation averaged 14.9 g/dl, 41.8%, 300 micrograms/dl and 59.4%, respectively, on the day of birth. These values were significantly reduced after 14 days, but had approached again the initial levels by day 28. There was a slight, statistically nonsignificant rise in the mean total iron-binding capacity over the four-week period. Iron status was not affecting by the sex of the foals. On the day of parturition, the mares had much lower levels of plasma iron and transferrin saturation than their foals. In the discussion, the importance of checking the iron status of each individual foal during the critical period of the first 14 days post partum is stressed.

Animals↗
PubMed1988

Determination of endogenous manganese excretion in broiler chicks by an isotope-dilution method.

A tracer study with broiler chicks was conducted to determine endogenous Mn excretion in response to graded levels of dietary Mn supply by the isotope-dilution method. Starting with 46 day-old chicks, low-Mn diets were fed for 12 days before 8 chicks were slaughtered for assessing the initial Mn status and 38 chicks each were given an intramuscular injection of 555 kBq 54Mn. Four groups of six birds each were fed, one bird per cage, diets containing 2.8, 9.1, 25.8, and 59.7 ppm Mn for 16 days before slaughter and carcass analyses. Two groups of 7 birds were fed the diets with 9.1 and 25.8 ppm Mn for 8 days. Mn supply significantly affected 54Mn excretion and its distribution among various body organs, especially the liver. The specific activity of Mn in excreta and in whole-body declined exponentially with time and differed between groups. Endogenous Mn in excreta was estimated on the basis that the specific activity of excreta Mn from day 9 to 12 and day 13 to 16 was reflected, on the average, by that of liver Mn on day 10 and 14, respectively. It averaged in the order of increasing Mn supply 12.5 vs. 12.0; 7.7 vs. 8.5; 3.9 vs 4.3, and 2.0 vs 2.3% of total excreta Mn. Total Mn excretion from day 9 to 16 averaged 88.9, 95.0, 97.9, and 98.9% of Mn intake.

Animals↗
PubMed1982

[Optimal zinc requirement of lactating dairy cows based on various dose-response relationships].

Dose-response relationships were established by multiple regression analysis of data from a zinc depletion-repletion study conducted with five first-lactation cows in order to estimate optimum zinc requirement. Zinc supply in the various experimental periods ranged from 6 to 436 ppm in the dry matter of the semisynthetic diet. The response criteria were the zinc concentrations in serum and milk and the activity of the alkaline phosphatase in serum. They correlated best with the reciprocal of the dietary zinc concentrations. Serum zinc also showed a close negative relationship to daily milk production (9-24 kg) and milk zinc to stage of lactation (2-21 weeks post partum). The response of the activity of the alkaline phosphatase, which was sufficiently described by simple regression to the inverse of dietary zinc concentration, was limited to a distinctly lower zinc supply range than the response of the serum and milk zinc level. The optimum zinc requirement of the cows was estimated to have been met with about 35 ppm Zn in the ration on the basis that 90% of the maximum response of the serum and milk zinc concentration was reached at this supply level. In the practical feeding situation, dairy cows should, however, be allowed 50 mg zinc per kg dry matter intake according to current recommendations in order to make certain that the physiological capacity of milk to bind zinc is sufficiently fulfilled even at highest milk production.

Alkaline Phosphatase↗
PubMed1981

[The contribution of betaine and glutamic acid to nitrogen digestion and balance during feeding of vinasse to growing pigs].

A conventional balance trial was conducted with growing pigs to study to what extent betaine and glutamic acid contained in vinasse (condensed molasses solubles) contribute to N digestion and balance. Five pigs each were given either a basal diet (95% ground barley + 5% cellulose) or a mixed ration of 77% basal diet plus 23% vinasse, based on dry matter (DM). The vinasse contained, per kg DM, 29.6 g N, 27.7 g NPN, 22.5 g betaine, 32.9 g "free" total L-glutamic acid, of which 96% was pyrrolidone carboxylic acid plus glutamine. For these N fractions of the vinasse, mean apparent digestibilities were 44.7, 63.8, 99.8 and 97.6%, respectively. Accordingly, betaine and total glutamic acid contributed 20 and 23%, respectively, of the apparently digestible total N of the vinasse. The pigs given vinasse excreted, per day, 257 mg more betaine and 364 mg more trimethylamine-N-oxide with their urine than the group given the basal diet. The contribution of betaine N of the vinasse to the N balance of the pigs on the mixed ration amounted to 11%.

Animal Feed↗
PubMed1980

Total true efficiency of zinc utilization: determination and homeostatic dependence upon the zinc supply status in young rats.

Total true efficiency of zinc utilization and its component factors, true absorption and metabolic efficiency, were studied in relation to dietary zinc supply in a 15-day experiment with 36 weanling rats in six groups. After day 3, the initial supply of 18.2 ppm zinc in the diet for all groups was changed to 5.6, 10.6, 18.2, 39, 70 and 141 ppm in groups 1 to 6, respectively. During the 6-day balance period after day 9, zinc intake was proportional to dietary zinc concentration. Mean daily rates of weight gain and apparent zinc retention increased from a near zero level in group 1 to a high plateau from group 4 to 6. True absorption rate steadily rose and reached about twice that of apparent absorption in group 6. This difference in rates was due to endogenous zinc excretion. Percent total utilization and percent true absorption steadily declined from a mean of about 100 in groups 1 and 2 to nearly 15 and 30, respectively, in group 6. Metabolic efficiency, reflecting true retention of absorbed zinc, similarly declined as percent true absorption did. The major conclusion was that not only the absorptive but also the metabolic efficiency greatly contributed to zinc homeostasis and total true efficiency of zinc utilization.

Absorption↗
PubMed1978

Homeostatic adjustments in zinc digestion to widely varying dietary zinc intake.

A 15-day Zn balance study was conducted with 36 growing rats maintained on a casein diet with 18.2 microgram Zn/g from day 0 to 3. Thereafter, six rats each were given the diet with the following variates of Zn content (microgram Zn/g): 5.6, 10.6, 18.2, 39, 70, 141. Zn digestion adjusted to the change in dietary Zn intake within the first 6 days via control of the extent of intestinal Zn absorption and fecal excretion of endogenous Zn. From day 9 to 15, mean apparent Zn digestion ranged from 92 to 18% and Zn absorption from 100 to 34% in an inverse relation to Zn intake. At the supply of 39 and 70 microgram Zn/g of diet, fecal excretion of endogenous Zn amounted to nearly one fourth of the dietary Zn intake. Reduction of intestinal absorption became the major factor to confine Zn accretion by the body when Zn intake was in great excess above requirement. Endogenous fecal Zn excretion exhibited its greatest homeostatic response in the range of optimum Zn intake. Zn excretion via the kidneys did not partake in Zn homeostasis, except that it was a major drain of body Zn compared to the intestinal route at low Zn intakes.

Animals↗
PubMed1977

A comparative view on trace elements and growth.

The term 'essentiality' of trace elements is interpreted. The major human diseases due to trace element deficience (Fe, Cu, Zn, Cr) are briefly considered. In growing animals the first clinical deficiency symptom most often is a growth retardation. In order to diagnose a deficient situation before the manifestation of clinical symptoms, model studies with growing animals are presented to show criteria that respond sensitively even to suboptimum intake of trace elements (Zn, Cu, Fe, Ni). Activity measurements of enzymes and hormones are found suitable. During the phase of reproduction, which is closely associated with growth, the trace element concentration in milk may provide an additional diagnostic means. In conclusion, the problems of diagnosing the supply status are discussed. A possibility for determination of the trace element requirement is indicated.

Animals↗
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↗