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Biomedical subjects

O Simon

Publications and source records attributed to O Simon.

At least 91 records · Page 5Linked to original sources
PubMed1982

Investigations on the amino acid secretion and absorption in the stomach of the growing pig.

Two pigs of 35 kg live weight were fitted with re-entrant duodenal cannulas anterior to the pancreatic duct and fed barley-soya or casein-wheat starch diets prior to the experiment. After 24 hours fasting they were given a single meal of 15N-labelled free amino acids-wheat starch (A) or 15N-labelled wheat (B) diets and digesta leaving the stomach was collected during 12 hours. The proportion of TCA soluble N in total N of digesta increased with time from 10 to 40% with diet B and decreased from 90 to 47% with diet A. Total N leaving the stomach within 12 hours accounted for 96% and 106% of N ingested on diet A and B, while the amount of 15N accounted for only 66 and 86% of 15N given in diets A and B, respectively. The content of endogenous N in the digesta was 1.22 g/12 h after feeding diet A and 1.67 g/12 h after feeding diet B. It was concluded that considerable amounts of N are secreted and absorbed in the part of the digestive tract proximal to the opening of the pancreatic duct.

Absorption↗
PubMed1982

Flow of endogenous and exogenous amino acids along the gut of pigs.

Digesta were collected from 5 pigs of 33 kg live weight fitted with re-entrant cannulas in the duodenum (within 20-30 cm of the pylorus) and terminal ileum. The pigs received a diet of barley, soya bean oilmeal and a vitamin and mineral mixture. The flow rates of digesta, total nitrogen and the individual amino acids were measured at different time after feeding and during two 24 h periods. A marked increase in the flow of digesta, nitrogen and amino acids was seen in the duodenum after feeding. Total flow during 24 h of nitrogen and amino acids except His, Val, Leu, Phe and Met exceeded intake. Output of nitrogen and amino acids from the duodenal cannula was 117 and 108% of intake, respectively. A method to calculate the ratio of endogenous amino acids in digesta based on the amino acid composition of digesta, diet and endogenous secretions was developed. The calculated amounts of endogenous amino acids passing the proximal duodenum and terminal ileum were 32.2 and 21.9 g per 24 h, respectively. The greatest amount of endogenous amino acids passed through the duodenal cannula in the first two hours after feeding (2-3 g/h) and then gradually decreased to 1 g per hour. The results are discussed in relation to other studies on the secretion of endogenous protein and its amino acid composition.

Amino Acids↗
PubMed1981

[A new method for testing the quality of food proteins for maintenance metabolism. 4. Testing of isolated proteins as well as various protein sources of plant and animal origin].

Male adult rats (370 g body weight) were fed on maintenance level (460 kJ ME/kg 0,75). In a 10 days preliminary period they received a casein/methionin diet (95,5 W/W) supplemented with 10 mg N-15-excess per 0,178 kg metabolic body weight in form of ammonium acetate. Thereafter the animals were changed on 8 isonitrogenous diets containing as protein sources casein, soya protein, gelatine, whole egg, fish meal, pea, wheat and yeast. The N-15-excretion via urine and faeces 6th and 10th day after the end of labelling period was used to evaluate the dietary proteins for maintenance. N-15 in urine was lowest in animals fed with the wheat diet and highest after feeding the whole egg diet. From these data a so called "N-15-excretions BV" was calculated, which indicated the highest quality for wheat and soy protein in meeting the needs of the intermediary metabolism in maintenance. On the other hand, dietary protein sources influence the loss of endogenous nitrogen as metabolic faecal nitrogen (MFN). It was found to be lowest in animals fed with diets containing isolated proteins (6 mg MFN/100 g body weight) and highest after feeding protein sources of plant origin with a high content in crude fibre (10 mg MFN/100 g). Both, losses of N-15 via urine and via feces were combined in a parameter called "total BV". According to this parameter the differences in quality for maintenance were only little between the protein sources testet (casein 100, soy protein 100, pea 99, wheat 99, whole egg 92, fish meal 89, gelatin 89). It was concluded that in maintenance the supply with indispensable amino acids is not critical and that the supply with dispensable amino acids (or nonspecific nitrogen) is of great importance.

Amino Acids↗
PubMed1981

[A new method for testing the quality of food proteins for maintenance metabolism. 3. Methodological studies of 15N-labeled adult rats].

Experiments were made in order to estimate the optimum amount of daily N-15-application and the optimum period for labelling adult rats in maintenance conditions with N-15-ammonium acetate. Labelling periods of 7 and 10 days were combined with 10 or 30 mg N-15-excess per day and 0,178 kg0,75. N-15-label in urine growth to a plateau within 3--4 days during N-15-feeding. After omitting N-15 from the diet the N-15-label declined rapidly and reached again a relative stable value within 3 to 4 days. The curve pattern for N-15-label in faeces was similar, however, with a time lag of about 24 hours. The ratio between N-15-label in faeces was similar, however, with a time lag of about 24 hours. The ratio between N-15-label in urine and faeces was constant from the 6th to 10th day after the labelling period. Therefore, this period should be used for the estimation of metabolic faecal nitrogen on the basis of N-15-label of nitrogen in faeces and N-15-label of endogenous nitrogen secreted into the gastrointestinal tract. Both, N-15-label of urine and N-15-label of TCA-soluble fraction of plasma can be used as a indicator of the N-15-label of endogenous faecal nitrogen. But, from methodical point of view urine seems to be more convenient. Among the variants of labelling tested the best was found to be a 10 days period with 10 mg N'--15/0,178 kg0,75 daily.

Acetates↗
PubMed1981

Effect of thyroid hormones on the in vivo protein synthesis in rats.

The studies were made in order to estimate the rate of tissue protein synthesis in euthyroid, hyperthyroid and hypothyroid rats (110 g body weight). Hyperthyroidism was simulated by daily oral application of 4,44 micrograms thyroxine (T4) and 0,89 micrograms triiodothyronine (T3)/100 g body weight. Hypothyroidism was induced by oral application of 17,8 mg of methylthiouracil (MTU) per day and 100 g body weight. In both cases the treatment lasted for 7 days. The concentration of both hormones in blood serum was twice that of the control group in the T3 + T4 treated group. The MTU application produced a decrease in T3 and T4 concentration to levels below the lower detection limits of the methods used. The fractional rate of tissue protein synthesis was estimated using the constant intravenous infusion technique with L-14C-leucine and L-14C-lysine simultaneously. The range of the fractional rate of protein synthesis was found to be higher in hyperthyroid than in control animals in all organs under study (liver, small intestine, large intestine, gastrocnemius muscle and pancreas). Protein synthesis was stimulated to the greatest extent in muscle (4,5--5,1% . d-1 in controls vs, 5,5--6,7% . d-1 in hyperthyroid animals). The influence of hypothyroidism on the rate of protein synthesis was uncertain.

Animals↗
PubMed1980

[A new model of multiple sclerosis. Experimental vaccinia infection in the monkey].

Experimental vaccinia infection in immunosuppressed and immunocompetent Rhesus monkeys has been studied for two years. The results show that vaccinia virus induces two forms of infection in the central nervous system, i.e. choriomeningitis and demyelination disease. The first form occurs in immunologically competent animals; the latter can develop in animals with defective immune response associated with an incomplete clearance of virus. These animals exhibit a noncytocidal persistent infection of glial cells, inducing a complex of potentially pathogenic immune mechanisms. Their direct, or by mediators mediated action is capable of damaging myelin sheaths.

Animals↗
PubMed1980

[Investigation of the feed value of straw].

Two groups of four pigs each were fed ad libitum with rations containing 70.7% barley, 7.7% fish meal, 0.7% Sussopan, 0.9% mixed minerals and 20% straw meal. Group 1 received partly hydrolysed straw meal, group 2 untreated straw meal. When those rations were given, weight increase performances of 767 g per animal and day in group 1 and 537 g per animal and day in group 2 were achieved in a preliminary 30-day feeding period. On the basis ofthe weight of the feed remnants, a consumption of 19.7% dry matter of the straw meal (group 1) resp. 18,5% (group 2) of the total intake of dry matter could be ascertained. At an average live weight of 93 kg (group 1) resp. 87.5 kg (group 2) the digestibility of both rations was examined. A significant difference was only found for the crude protein fraction with an apparent digestibility of 74.6% in group 1 and of 79.1% in group 2. Those pigs which received partly hydrolysed straw meal consumed 71.4 g N per animal and day, of which 25,4% were excreted in feces and 32.4% in urine. Those animals which were fed with untreated straw meal consumed 62.9 g N per animals and day of which 20.8% were excreted in feces and 49.7% in urine. The higher N-excretion in feces could also be proved for most amino acids the feeding with partly hydrolysed straw meal. For arginine, serine, glutamic acid, proline, isoleucine and Leucine these differences were significant. Differences concerning N-retention could not be found between the groups. 25% of the organic matter of the partly hydrolysed straw meal, 9.4% of the crude fibre and 44.2% of the N-free extractives were digestible. Of the untreated straw, 12.9% of the organic matter, 5.5% ofthe crude fibres and 21.7% of the N-free extractives were digestible. 193 EFpig were calculated for partly hydrolysed and 105 EFpig for untreated straw meal per kg dry matter. The result of substracting the CaCl2 of the partly hydrolysed straw meal is 205 EFpig per kg dry matter of the straw.

Animal Feed↗
PubMed1979

[Action of proteinase inhibitors in rats. 3. Influence of leupeptin on the rate of protein synthesis and the intracellular protein degradation by use of a test system including constant infusion of labelled amino acids, estimation of 3-methyl-histidine excretion and a triple-labelling technique].

Male Wistar rats (initial body weight 90 g) were fed ad libitum a whole-egg diet containing 10,5% crude protein. The animals of the experimental group received in each case of 1 mg leupeptin per 100 g of body weight in 12 hrs-intervals by i. p.-injection (3 days of treatment). Control animals got a leupeptin free solution. In addition, lysine dihydrochloride-alpha-15N was applied during the first three days of experiment to all animals and the nitrogen balance was determined. Urine from the N-Balance collection was analysed for 3-methyl-histidine excretion in order to calculate the degradation rate of myofibrillar proteins. On the fourth day the fractional rate of protein synthesis in several organs was estimated using the continuous infusion technique with 14C-leucine and 14C-lysine. The apparent biological half-lives of tissue protein were determined by a triple labelling technique, with (14C)-guanidino-L-arginine, L-5-3H-arginine and 15N-Lysine. The short-term treatment 3 days) with leupeptin did not affect the weight gain, the apparent digestibility of nitrogen and the N-balance. The fractional rate of protein synthesis was highest in the small intestine followed by the large intestine, liver and skeletal muscle and no influence of leupeptin treatment was observed. Furthermore no differences in the degradation rates of myofibrillar proteins between treated and untreated animals were found. The 3-methyl-histidine excretion via urine was 1.44 mg . kg-1 day-1 in both groups corresponding to a fractional rate of degradation of myofibrillar proteins of 2,5% per day. Apparent half-lives of tissue proteins in the small intestine, large intestine and liver, respectively, were shortest when estimated from the decay curves for the 14C-label and longest from the curves for the 15N-label. Leupeptin treatment resulted in prolonged apparent half-lives of the proteins in the large intestine and of the slowly turning over proteins in the liver. However, this effect seems to be caused rather by an increased reutilization of labelled amino acids than by a decreased protein degradation. Before continuing this kind of work the rate of uptake of injected leupeptine into tissues has to be investigated. Studies dealing with the in vivo action of proteinase inhibitors on protein metabolism have to include estimations of N-balance, protein synthesis rate, intracellular degradation rate of proteins as well as amino acid reutilization.

Amino Acids↗
PubMed1978

[EEG changes following spirolactone treatment (author's transl)].

EEG studies were done on patients with CNS disease who were treated with d-aldosterone and spirolactone. The baseline EEGs of these patients were found to be slightly abnormal. During infusion of the spirolactone derivative potassium canrenoate a transient deterioration of preexisting EEG disturbances was observed; in addition, bursts of increased muscle activity and transient relative bradycardia were seen. These findings indicate that potassium canrenoate or its lipophilic metabolite canrenone may affect the nervous system directly, possibly via a disturbance in the electrolyte balance. These results are compatible with recent findings in animal studies.

Aldosterone↗
PubMed1978

Estimation of rate of protein synthesis by constant infusion of labelled amino acids in pigs.

1. The fractional synthetic rates of tissue proteins were studied in growing pigs using the constant-infusion technique of tracer-labelled amino acids ([14C]leucine and [14C]lysine) and the mathetmatical model for calculation, employed in rats by Garlick, Millward & James (1973). 2. During a 6 h infusion, samples were taken from blood and muscle and at the end of the infusion from liver, muscle, pancreas, heart, duodenum, jejunum, ileum, colon, and skin. The specific radioactivity of free and protein-bound leucine and lysine was estimated. 3. A quasi-steady-state in the specific radioactivity of free plasma leucine and lysine was reached within approximately 2 h, the rate-constants being 35 and 48/d respectively. 4. The specific radioactivity of free leucine and lysine in plasma was used to calculate the flux of these amino acids. It was found to be higher than the daily intake. 5. The average fractional rate of protein synthesis in muscle and heart 8.1% d, in small and large intestine the values were 50 and 33% d respectively and in liver and pancreas more than 100% d. 6. The calculation of protein synthetic rate in pig tissue using the constant-infusion method of labelled amino acids seems to be a suitable toof for study of this species.

Animals↗
PubMed1978

[Characterization of radioactivity distribution in the organism during constant intravenous infusion of tracer amino acids and calculation of the rate of tissue protein synthesis in rats].

Male wistar rats (100 g live mass) were given infusions into the tail vein of 14C-leucine and 14C-lysine simultaneously for 0.5; 1.0; 2.0; 3.0; 4.5; 6.0 and 7.0 hours. At the end of the infusion the specific radioactivity of the free leucine and lysine in the blood plasma, liver, M. gastrocnemius, small intestines and colon were ascertained as well as after the 6-and-7-hour infusion that of the protein-bound leucine and lysine. In all tested tissues the specific radioactivity of the free amino acids attained a plateau during the 6-and-7-hour infusion. The rate constants for the increase were calculated for each organ tested. The two amino acids used are suitable for the calculation of the fractional rate of protein synthesis in tissues. The values of the fractional rate of protein synthesis calculated on the basis of the 6-and-7-hour infusion were: 54 +/- 7.7%/day for the liver, 9.4 +/- 1.2%/day for muscles, 89 +/- 12.2%/day for the small intestines and 42 +/- 5.9%/day for the colon. The simultaneous application of two tracer amino acids is recommendable for the estimation of the precursor pool for protein synthesis and the more accurate calculation of the rate of protein synthesis.

Amino Acids↗
PubMed1978

[Metabolism-oriented lysine requirement of mature rats based on the catabolism rate for 14C- and 15N-labelled lysine].

Mature male albino rats (ca. 300 g body mass) received 10 diets with a varying lysine content (1.6 to 8.4 g/16 g N). In one partial test the animals were fed ad libitum and in another partial test they were kept in the state of maintenance by limiting the amount of the diet. After 7 feeding days the catabolisation of 14C-lysine into 14CO2 was measured and after 8 feeding days the 15N-excretion in urine after 15N-lysine doses was ascertained. Based on these characteristics typical of metabolism, which show increased catabolisation of the amino acid after the lysine requirement was met, the lysine requirement of a mature rat was determined as 3.5 to 4.0 g/16 g N in the diet. In conclusion, this shows that the lysine requirement in the state of maintenenace and of mature animals is considerably lower than during the period of growth.

Animals↗
PubMed1978

[Determination of lysine requirement in growing rats as based on the catabolism rate of 14-C- and 15-N-labeled lysine].

Male Wistar rats (weighing some 80 g at the start of the experiment) were fed diets containing maize gluten as protein carrier and which was supplemented with amino acids (except lysine) in such way that their concentrations came up to the requirement norms. Lysine was gradually supplemented this resulting in 10 diets of different lysine content (1.6-10.6 g lysine/16 g N). On the 7th experimental day, 4 animals of each group were labelled with 14C-lysine and subjected to 2-hour measuring of 14CO2-excretion. On the following day, the animals were injected i.p. 15N-lysine, the urine being collected over 24 hours to determine 15N-frequency in urine. Both 14CO2-excretion and 15N-frequency in urine were found to remain constant at a lysine content of the diet up to 4.5 g/16 g N and rose steeply from 5.8 g lysine/16 N on. Under the experimental conditions chosen the lysine requirement is deduced to be 5 g/16 g N. This method of lysine requirement determination is highly sensitive and exact because it covers the catabolization of the amino acids under study and not so parameters that are known to be influenced by other factors such as growth, N-balance, total N-conversion or CO2-formation. The method can also be applied to metabolic situations not connected with productive performances.

Animal Nutritional Physiological Phenomena↗
PubMed1977

The definition of waking stages on the basis of continuous polygraphic recordings in normal subjects.

Polygraphic examinations were made during the day on 6 normal subjects. Simultaneous evaluation of EEG, EOG and EMG was carried out over 30 sec epochs. The data thus obtained were correlated with the various types of behaviour and activities during the day and then interpreted. Six conditions could be defined corresponding to different waking stages. The analysis of the material obtained shows that the existence of these waking stages is of interindividual validity.

Adult↗
PubMed1977

[Secretion of radioactively labeled amino acids into the digestive tract. 2. 14C labeling and amount of 14C leucine in the intestinal contents after subcutaneous injection of 14C leucine in rats].

Experimental rats received a subcutaneous injection of 14C of varying activity. The rats were then killed in groups within a period of from 2 mins to 30 mins after the injection. A certain amount of 14C activity was detected in the intestinal contents as early as 2 mins after the injection, both as free 14C leucine and in the TCE soluble portion of the intestinal contents (TCE=trichloroacetic acid). A comparison of the degree of labelling in the TCE soluble and the TCE precipitable fractions of the intestinal contents showed that the most likely way for free 14C leucine to get into the lumen of the intestine is via the pancreatic juice while that for protein-bound 14C leucine is through the proteins in the pancreatic gland. The degree of labelling in both fractions decreased very steeply from the first to the third third of the intestine. This may be caused either by absorption of the secreted 14C leucine or may be brought about by a delay in food passage through the intestine.

Amino Acids↗
PubMed1977

[The secretion of radioactively labeled amino acids into the digestive tract. 3. 14C-labeling of the intestinal wall after subcutaneous injection of 14C-L-leucine in rats].

Experimental rats allotted in 4 different groups received 14C leucine injections at 4 different levels of specific 14C activity. Groups A and B were injected a leucine dosis corresponding to the daily requirement, the specific 14C activity being high (A) and low (B). Groups C and D were injected a leucine dosis of one ninth the amount applied to groups A and B, the level of 14C labelling being again high (C) and low (D). The 14C labelling of the TCE-soluble fraction of the 1st third section of the small intestinal wall in all 4 groups proved identical with the course of the curve representing the TCE-soluble fraction of the small intestine contents. The specific 14C leucine activity of the intestinal wall of the 1st third section of the small intestine was found to be 5 to 8 times lower than in the TCE-soluble fraction of the pancreatic gland. Thus a dilution effect has been produced from absorption. Two minutes after injection, the 14C labelling of the intestinal wall proteins had half the level of labelling of the pancreatic proteins. This finding applied to both the 1st and the 3rd sections of the small intestine. The results obtained allow to conclude that 14C labelling of intestinal wall proteins is relatively independent of 14C leucine absorption and is conditioned by the level of labelling of the plasma leucine.

Animals↗