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Biomedical subjects

M Stangassinger

Publications and source records attributed to M Stangassinger.

50 records · Page 3Linked to original sources
PubMed1982

Caecotrophy-dependent changes in the metabolic fate of D(-) lactic acid in rabbits.

In rabbits the influence of the reingestion of special faeces on gastric as well as on intermediary metabolism of [U-14C]-D(-) lactic acid has been studied. In unrestrained animals there was no naturally occurring D(-) lactic acic concentration measurable either in stomach contents or in blood. Orally loaded D(-) lactate was almost completely decomposed in the stomach and absorbed within 15 min. Thereby intermediary oxidation was equally affected. Thus, in rabbits prevented from caecotrophy the exhalation rate of 14CO2 derived from [14C]-D(-) lactic acid at 2 h after oral application was reduced to about 65% of the rate of unrestrained animals. Similar low oxidation rates have been obtained only if [14C]-D(-) lactate was injected intraperitoneally. One can conclude from these experiments that caecotrophy in rabbits prevents the accumulation of D(-) lactic acid in the stomach by rapid bacterial transformation but increases the rate of its intermediary oxidation by absorption of these transformation products.

Animals↗
PubMed1979

The effect of rumen epithelial development on metabolic activities and ketogenesis by the tissue in vitro.

1. An investigation was made on oxygen consumption, glucose and lactate uptake and ketogenesis from butyrate by rumen epithelium in vitro from lambs at various stages of development. 2. Oxygen uptake was decreased by about 35% and glucose uptake by about 90% between 2 weeks and 1/2 year of age. 3. The uptake of L-lactate and the utilization of butyrate as a substrate for respiration were increased during epithelial development. 4. The production of D(-)-3-hydroxybutyrate and acetoacetate from butyrate by the epithelium was largely increased between 4 to 10 weeks of age, independently of rumen fermentation. 5. A synergistic effect of glucose on the production of D(-)-3-hydroxybutyrate and on total ketone bodies from butyrate by the epithelium was observed. It accounted to 40-80% over butyrate depending on the stage of epithelial development.

3-Hydroxybutyric Acid↗
PubMed1979

Specific methods for the determination of radioactivity in D-(-)-3-hydroxybutyrate in blood plasma.

Two simple, high-yield rapid methods with good reproducibility are described, which permit the determination of radioactivity in plasma D-(-)-3-hydroxybutyrate. The compound is converted to acetoacetate, using a modified enzymatic method. In procedure 1, acetoacetate is reacted with 2,4-dinitrophenylhydrazine; the resulting hydrazone is oxidised by means of a sample oxidiser, and the product 14CO2 is collected in scintillation liquid and counted. In procedure 2, a Conway microdiffusion unit is applied. The acetoacetate is decarboxylated to acetone in the presence of o-phenylenediamine, and the acetone is then diffused into semicarbazide solution. This solution, containing the semicarbazone derivative of labelled acetone, is transferred to liquid scintillation and counted. In both procedures the radioactivity is measured simultaneously in a separate sample which was not subjected to the enzymatic conversion of D-(-)-3-hydroxybutyrate. The difference in radioactivity between the two samples is attributed to labelled (D-(-)-3-hydroxybutyrate.

Carbon Radioisotopes↗
PubMed1979

Quantitative measurement of gluconeogenesis from isobutyrate in sheep.

Experiments with continuous infusion of [14C] isobutyrate and single injection of [3H] glucose were performed in two sheep under fed and fasted conditions in order to investigate the contribution of isobutyrate to glucose synthesis. The pool size, total entry and irreversible loss of glucose in the fed sheep were 2.8 mmol/kg0.75, 1.70 and 1.43 mmol/h per kg0.75. After 72-h fasting these parameters decreased about 40% but recycling of glucose carbon increased from 16 to 38% of the total entry rate. Isobutyrate infused intravenously at a rate of 3.5 mmol/h contributed to a minimum of 3-5% of glucose entry indicating that at least 40-60% of the infused isobutyrate was used for net glucose synthesis. The efficiency of the glucogenic and energetic use of isobutyrate as compared to propionate is discussed.

Animals↗
PubMedDate not supplied

Effects of intake level of a mixed diet on chewing activity and on particle size of ruminated boli, ruminal digesta fractions and faeces of steers.

This study evaluated the effects of intake of a mixed diet on chewing activity during eating and rumination and the relationship between the chewing activity and the particle size of the ruminated boli, ruminal digesta fractions and faeces in steers. Six ruminally cannulated steers received a mixed forage/concentrate diet (68:32, dry matter basis). The diet was offered twice daily at approximately 1, 1.5 and 2 times the estimated maintenance energy requirements (low, medium and high intake, respectively) in a repeated 3 x 3 Latin square design. The rumens were emptied manually and samples of the ruminated boli and of the ruminal upper strata were collected at four different times throughout the day. The dry matter weight distribution of the total amount of recovered particles was determined by a wet-sieving procedure. Numerically, the effect of intake on the mean particle sizes of the different materials was small. However, the mean particle size was reduced by almost nine tenths from their size at intake of the mixed diet (4.78 mm) to defecation (0.51 mm). The total number of minutes chewing and eating and ruminating increased as the intake level increased. When related to 1 kg of dry matter intake, only the eating and chewing times were significantly longer for the high as compared to the medium intake. Rumination patterns were examined using a cosinor model. Data indicated that the average amount of time spent ruminating also increased as the intake level increased. The overall pattern of rumination was not impaired by higher intake levels. The amount of large (> or = 4 mm) particles that escaped per minute of rumination time between 3 and 7.5 h postfeeding was similar for all the intake levels. It was concluded that an active breakdown process occurred in the rumen which could cope with the higher intake levels of the mixed diet over the range of 1 to 2 times the maintenance energy requirement level.

Animal Feed↗
PubMedDate not supplied

The humoral immune response and the productivity of laying hens kept on the ground or in cages.

The effects of two different keeping systems on the humoral immune response and productivity were compared for 80 laying hens, divided into four groups. Two groups each of 20 hens were kept on the ground and two were kept in cages. All the birds were immunised subcutaneously with human serum immunoglobulin G (IgG) at a dose of 100(microg per injection. The immunisations were performed twice at 4-week intervals. The lipopeptide Pam(3)Cys-Ser-(Lys)(4) was used as an adjuvant at a dose of 0.25mg per injection in one group from each housing system. In the second group from each housing system, the hens were immunised without any adjuvant (antigen control groups). The mean egg yield was significantly higher in both the antigen control group and the adjuvant group, when laying hens were kept in cages. Total egg weight remained constant in both of the housing systems. Keeping hens in cages resulted in higher mean specific antibody titres and mean immunoglobulin Y concentrations in the egg yolk.

Adjuvants, Immunologic↗
PubMedDate not supplied

Protective effect of vitamin E in a rat model of focal cerebral ischemia.

Under certain pathological conditions such as cerebral ischemia and reperfusion the occurrence of free radicals is remarkably increased. However, only very little information is available on their quantitative relevance for the pathophysiology and final outcome of diseases. The aim of the present study was to evaluate the contribution of oxygen radicals in the pathogenesis of a stroke. For this purpose a rat model for stroke was used. Two of three vitamin E deficient groups were repleted with different dosages of DL-alpha-tocopherylacetate. No signs of vitamin E deficiency could be observed. However, the weight gain during repletion was increased in the vitamin E repleted groups. Brain infarction was created by occlusion of the right middle cerebral artery (MCAO) for two hours. After 24 hours the measurements of infarct volumes were taken. The infarct volume of the group with the highest repletion dosage was significantly reduced by 81%. This was also expressed in a higher rate of gait disturbances after MCAO of the deficient animals. The control of vitamin E status exhibited a similar repletion-dependent level in plasma and brain. These results strongly support the hypothesis that the generation of oxygen radicals occurring during reperfusion is an important aspect of the pathophysiological mechanism in brain infarction.

Animals↗