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E Weigand

Publications and source records attributed to E Weigand.

29 records · Page 2Linked to original sources
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↗
PubMed1975

Volatile fatty acid metabolism by rumen mucosa from cattle fed hay or grain.

Effects of an all-grain versus an all-hay diet on metabolic activity of rumen mucosa of cattle were investigated. After diets had been fed for 3 to 4 mo, rumen papillae were collected at slaughter from the dorsal rumen sac and incubated with one of various volatile fatty acids. Rates of substrate utilization were in the order: n-butyrate greater than n-valerate approximately propionate greater than iso-butyrate approximately iso-valerate. Over-all, papillae from hay-fed steers utilized greater amounts of volatile fatty acids. Dietary treatment did not significantly affect extent of conversion of volatile fatty acids to lactate and to ketone bodies. Lactate was the major metabolite from propionate and n-valerate. Ketone body formation accounted for more than 90% of n-butyrate uptake by papillae. Ketone formation from n-valerate was restricted to beta-hydroxybutyrate while that from iso-valerate was essentially acetoacetate plus acetone. Metabolic systems in rumen mucosa of physiologically mature ruminants seem to adapt little to varying individual volatile fatty acids available for absorption in vivo.

Acetoacetates↗
PubMed1972

Extent of propionate metabolism during absorption from the bovine ruminoreticulum.

1. Solutions containing acetate, [2-(14)C]propionate and butyrate were placed into the ruminoreticulum of calves to measure the extent to which propionate is metabolized by ruminoreticulum epithelium. In response to five different combinations of pH and total volatile fatty acid concentrations, propionate absorption rates ranged from 89 to 341mmol/h. 2. The extent of propionate conversion into lactate, calculated from both concentration and specific radioactivity in portal and arterial blood, averaged 4.9 (range 2.5-9.1)%. 3. Circulating glucose synthesized from propionate had a higher specific radioactivity than arterial lactate and was converted into lactate by gastrointestinal tissues. Thus conversion of propionate into lactate was overestimated but was corrected to average 2.3 (1.0-4.6)%. 4. The estimates of propionate conversion into lactate were negatively correlated with its rate of absorption.

Absorption↗
PubMedDate not supplied

Pharmacological differentiation between neuronal and recombinant glutamate receptor channels expressed in Xenopus oocytes.

To determine the molecular components of neuronal glutamate receptors, it is important to identify pharmacological tools that allow differentiation between different glutamate receptor types. Here, we utilized the naphthalene derivative Evans Blue (EB) and a collection of other subtype-specific compounds (polyamine toxins, concanavalin A, cyclothiazide) to compare the pharmacological profile of neuronal and recombinant glutamate receptors GluR1-GluR6 expressed in Xenopus oocytes. Submicromolar concentrations of EB selectively reduced the activity of homomeric glutamate receptors GluR1, GluR2(Q) and GluR4. Applied at concentrations above 100 microM, EB potentiated kainate responses of receptors GluR1, GluR3 and GluR4, while receptors GluR2(Q) and GluR6(Q) were completely blocked. Similar experiments were performed on identified neurones in brain slices and after injection of rat brain RNA in Xenopus oocytes. Neuronal kainate responses were (i) potentiated by 100 microM cyclothiazide, (ii) slightly blocked after preincubation in 10 microM concanavalin A, and (iii) not significantly affected by either low (< 1 microM) or high (> 100 microM) concentrations of EB. Their pharmacological properties were markedly different from those of recombinant glutamate receptor channels GluR1-GluR6 investigated in heterologous expression systems.

Animals↗