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Biomedical subjects

H Bergner

Publications and source records attributed to H Bergner.

At least 109 records · Page 6Linked to original sources
PubMed1977

[Mode of action of proteinase inhibitors in rats. 2. Effect of leupeptin on N-balance and biological half-life in ad lib feeding].

During a 15-day period, growing Wistar rats (75 g) were fed ad lib. a whole-egg diet containing 10% crude protein (control group) and the same diet + a daily subcutaneous injection of 1 mg of leupeptin per animal (experimental group), respectively. To investigate the influence of the peptide aldehyde leupeptin on the M-metabolism, N-balance trials were carried out between the 1st and the 6th, and the 10th and the 15th experimental days. Leupeptine was not found to influence the true N-digestibility. However, the intermediary N-utilization, characterized by the biological value of the dietary protein, deteriorated in comparison with the control group. The peptide aldehyde under study resulted in an extension of the biological half-life of the proteins in the tissue of the small and large intestine. It was measured via the decline of radioactivity in protein following application of L-guanidino-14 C-arginine and L-(4,5-3H)-leucine. The amino acid utilization appears to have been increased as well. In connection with previous studies (SIMON et al., 1976) i, which, under somewhat different experimental conditions, leupeptine resulted in a higher intermediary N-utilization, the mentioned agent is supposed to be able to influence N-utilization. However, additional studies are required to make statements regarding the influence of dosis and metabolic situation.

Animals↗
PubMed1977

[Long-term feeding of acetyl urea to dairy cows].

After an introductory survey of investigations dealing with the conversion of acetyl urea in the ruminant organism, a feeding trial using dairy cattle is described in which the effects of long-term acetyl urea feeding on the clinical picture and various performance parameters have been studied. Five Black-Pied cows of medium milk yield were fed a natural diet and received, over at least 14 months, a daily acetyl urea supplementation of 430 g (= 40 to 44% of the digestible crude protein). The clinical control, including the analysis of blood parameters, did not produce any deviation from normal. As to milk and butterfat yields, the experimental group reached results comparable to those of the control group. Over the entire experimental period the experimental group and the control averaged per cow and day of milking 11.1 and 11.3 kg FCM, respectively. The reproductive behaviour proved normal for all the cows under study. Postmortem findings of 4 cows revealed, among other things, chronic kidney alterations that cannot be safely exluded to be caused by the experiments. A stress over several months of two cows fed 850 g acetyl urea per day was not found to affect animal performance and health.

Animal Feed↗
PubMed1977

[Isobutylidene-di-urea as a new NPN source for ruminants. 2. Metabolism of 14C-15N-isobutylidene-di-urea in sheep].

2 male sheep (weighing 45 kg and 44 kg) were fitted with a ruminal fistula and a jugular vein catheter and received isobutylidendi-urea for a 42-day period of adjustment. The diet contained 25% starch, 23.8% glucose, 29.0% cellulose, 10.0% straw, 1.7% sunflower seed oil, 4.3% isobutylidendi-urea, 5.6% minerals and vitamins. Each animal received 60 g of isobutylidendi-urea in daily amounts of 1.4 kg of the ration-4.4% of the total dietary N came from the straw. At the begin of the trial each sheep received 30 g of 14C15N isobutylidendi-urea (C1-siobutyl labelling) administered as a suspension. The animals were then placedin respiration cages. The peak of specific 14C activity in the expired air (including ruminal gas) was observed 2 hrs after the beginning of the trial. 18--30 hrs after the beginning of the trial the highest level of 15N incorporation into the TCE (trichloroacetic acid) soluble fraction of the ruminal fluid was noted resulting from the reflow of urea via the rumeno-hepatic circulatory system in the rumen. A high concentration of 15N was shown to be present, for prolonged period, in the TCE soluble fraction of the ruminal fluid (up to the 30 hr of experiment). The 15N concentration in the blood plasma (TCE soluble portion) was found to increase reaching a peak value 23 hrs after administration of the isotope. The highest level of 14C activity in this fraction appeared 1 hr after isotope administration. The 15N incorporation into the protein fraction of blood plasma reached a constant high level between the 29th and 47th hr of experiment. The highest 15N concentrations in urine were noted after 1 day. 3.5% of the administered dose of 14C activity and 23% of the supplied amount of N were excreted in the urine. 20% of the total amount of 15N excreted in the urine could be detected as 14C isobutyl residues. An excess of between 0.05 and 0.17 atom% of the isotopes were found in muscular tissue and in different organs of the sheep when these were slaughtered on the 7th day of experiment (liver: 0.17%, kidneys: 0.14%, muscle: 0.05%, heart: 0.08%). The results obtained in the present trial clearly indicate that ruminants are able to utilize nitrogen from isobutyldi-urea.

Animal Feed↗
PubMed1977

Studies on the in vivo-action of leupeptin on the nitrogen retention in rats.

A daily s.c. injection of 0.5 mg leupeptin for 7 days does not influence the digestibility of food-N but seems to improve the N-retention. A daily injection of 1.0 mg leupeptin for 14 days is without influence on the digestibility of N, too, but the N-retention was decreased. At this leupeptin level the half-lives of intestinal proteins were prolonged. The data indicate the possibility to influence the N-retention using leupeptin.

Animals↗
PubMed1976

[Secretion of endogenous amino acids in the gastrointestinal tract and amino acid resorption in the swine].

A trial was performed with 2 fistula pigs (each with 2 fistulas, one located about 30 cm below the pyloric orifice and the other at the end of the small intestine). Animal A received a casein diet containing 14% crude protein for a period of 2 weeks before the tracer amino acid was administered. Animal B received the same diet for a period of 10 days and was then fed a diet (at the same protein level) containing gluten as sole protein source. The two tracer amino acids, 14C-U-L-leucine and 3H-4,5-(N)-L-lysine, were injected intravenously. The passage rates for dry matter, organic matter and N measured at the beginning of the small intestine were higher than the rate of intake. The rate of passage of amino acids was also found to be increased relative to the rate of intake. In general, this increase involved the non-essential amino acids to a much larger extent. A considerable proportion of the amino acids passing into the large intestine is not excreted with the faeces but is probably converted in catabolic processes. It is for this reason that any values for the efficiency of amino acid absorption calculated on the basis of data on the faecal excretion of amino acids will not provide conclusive evidence for the availability of dietary amino acids in processes of the intermediate metabolism. The rate of secretion of 3H and 14C radioactivity into the digesta of the small intestine was found to increase rapidly within 1-2 hrs after administration of the tracer amino acids. The 14C radioactivity detected was found to be almost exclusively derived from 14C leucine while only about 60% of the 3H activity found in the digesta of fistula I were shown to be bound to lysine. Labelled lysine and leucine (of endogenic origin) are absorbed into the small intestine at a slower rate (i.e. endogenic proteins are less efficiently digested) than the non-radioactive amino acids (of exogenic origin) so that a process of concentration of endogenic amino acids is observed towards the end of the small intestine.

Amino Acids↗
PubMed1976

[The effect of proteinase inhibitors in rats. 1. Report. Effect of a short-term application on the N balance, the free amino acids in liver and muscles and the biological half-life of the intestinal tissue proteins].

Short-term trials with a triazin derivative and a peptide aldehyde were carried out to investigate the in-vivo administration of proteinase inhibitors in rats for improving the N balance of the animals. The results of N balances suggest that the peptide aldehyde may be regarded as a promising substance that may be used to increase the rate of utilization of the absorbed N in the intermediary metabolism. The short-term use of both active compounds did not affect the true N digestibility. The two compounds did not influence the concentration of free amino acids in the liver and muscle tissue under the experimental feeding conditions used. Similarly, tests of the biological half-life of proteins taken from the small and large intestine did not reveal any changes due to the presence of the inhibitors. Animals receiving a protein-free diet exhibited longer half-life periods for proteins from the small and large intestine compared with animals of the other groups. A protein-free nutrition of the animals caused a general increase in the levels of free non-essential amino acids in the liver. This was accompanied by a simultaneous decrease in essential amino acids. The same type of nutrition led to a general decline in the concentration of free amino acids in muscular tissue, particularly of the essential amino acids. High-protein nutrition led especially to an increase in the concentration of branched-chain amino acids in both types of tissues investigated.

Amino Acids↗
PubMed1976

[Isobutylene diurea as a new source of NPN for ruminants. 1. Nitrogen balance and plasma amino acid composition after feeding of isobutylene diurea to sheep].

The paper first presents a survey of the existing literature where studies on the effects of isobutylidene diurea (IBDH) as NPN source for ruminants are discussed. Following this the authors discuss their own experiments on IBDH turnover. IBDH showed no toxi cation when tested in toxicity studies with rats which were carried out under standardized conditions. Within the framework of metabolism trial 4 growing male sheep (average liveweight: 30 kg) were fed a semisynthetic diet containing IBDH as sole N source. Each animal received 60 g IBDH per day. The average value for the apparent N digestibility was found to be 77.6%, the percentage for the average N ballance was 27.6%. The blood of the sheep was investigated, on a comparative basis, for the behaviour of free amino acids after the administration of an experimental semisynthetic diet containing IBDH or extracted soya bean meal as sole N source. The use of IBDH produced a higher concentration of free amino acids and a five-fold increase if urea concentrations in the blood plasma but reduced the Asp, Cys and Tyr levels when compared with the feeding of extracted soya bean meal. Similarly, IBDH supplementation increased the relative proportions of Gly, Lys, and His in blood plasma but reduced those of Asp, Val and Tyr. A positive relationship between the rate of IBDH hydrolysis and the decrease in pH was found in experiments studying the hydrolysis behaviour of IBDH at pH values from 1-7.

Amino Acids↗
PubMed1976

[Studies on methods for the determination of amino acid requirements for metabolic balance based on the oxidation rate of 14C labeled lysine to 14CO2].

Male experimental rats (100 gm liveweight) were distributed into 10 groups of 8 animals each and received balanced diets, with the exception of lysine which was added to the diets in graded amounts in such a way that the lysine content of the diets ranged from 2.44 to 5.92 gm/16 gm N. After a feeding period of 7 days the animals received 3H- and 14C lysine injected intraperitoneally, 4 animals of each group were investigated for the total CO2 excretion and 14CO2 excretion during the first 2 hrs after the injection and for the urinary excretion of radioactivity (48 hours). The remaining animals in each group were used for determining the plasma amino acids and for establishing the specific radioactivity of free lysine in the liver and muscles after an 1-hour incorporation period. Total CO2 excretion was not found to be influenced by the lysine contents while the level of excretion of 14C activity through CO2 and that of specific 14C activity of CO2 increased with increasing lysine concentrations. This produced a broken curve pattern, showing an increased release of 14CO2 (under maintenance conditions) if the diet contained 4 gm lysine/16 gm N and more. Investigations for the specific 14C activity of free lysine in the liver, the main site of lysine oxidation, showed that the increase in 14CO2 release was due to an enhanced rate of lysine catabolism and was not brought about by changes in the pool volume or in specific radioactivity. The levels of urinary 14C excretion were not found to be related to the lysine content of the diets, whereas the curve pattern of 3H excretion observed 5 to 8 hrs after injection was similar to that of 14CO2 excretion. The lysine content of blood plasma and the content of free lysine in the liver increased continuously with increasing levels of dietary lysine. The methodological studies made in the present paper showed that in scientific research a determination of amino acid requirements on the basis of CO2 oxidation data may be a very exact and sensitive method. It will also yield values for maintenance requirements.

Amino Acids↗
PubMed1976

[Excretion of acetyl urea in milk following oral 14C-acetyl urea administration to dairy cows].

2 experimental cows were fed acetyl urea several weeks before the trial was started. The first cow received a daily amount of 200 g and the second cow 855 g. On the first day of experiment both cows were given 5 mCi of 14C acetyl urea intraruminally. Up to 6 hrs after the beginning of the experiment acetyl urea in blood plasma was shown to contain a higher proportion of 14C activity than urea. 0.21 g urea and 0.18 g acetyl urea were contained in 1 kg of milk from cow No 1 while 1 kg of milk from cow No 2 contained 0.18 g urea and 0.12 g acetyl urea. The feeding of acetyl urea to dairy cows is not recommended on the basis of the fact that any further contamination of human nutrition with foreign substances should be possibly avoided.

Animal Feed↗
PubMed1976

[Variations in the pattern of ruminal volatile free fatty acids, acetoacetate and glucose in the blood plasma of lactating cows after a period of fasting and renewed feeding].

3 lactating cows were fasted for 4 days and then again received food. The trial was performed to investigate the effect of fasting on the concentration and molar proportion of volatile fatty acids in the rumen, on the concentration of free fatty acids and glucose in blood plasma and on the acetoacetate concentration in the blood. Fasting produced a considerable decrease in the total concentration of volatile fatty acids. Processes of ruminal fermentation were characterized, during the fasting period, by a continuous increase in the molar proportions of acetic acid, isobutyric acid and isovaleric acid whereas a significant decline observed to occur in the molar proportions of propionic acid and butyric acid. The reciprocal behaviour of acetate and propionate under conditions of fasting lead to a linear increase in the C2 to C3 ratio from 4.4 : 1 to 9,6 : 1. With renewed food supply all fermentation data returned to normal levels. The concentrations of blood glucose declined after 24 hrs of fasting, remained at the same level for the following 2 days and rose again to normal values on the 4th day of fasting. The concentration of acetoacetate decreased significantly on the first day of fasting to values that were 4 times as high as the initial value. The concentration of free fatty acids in blood plasma increased tremendously to a value 40 times as high as that observed at the beginning of the fasting period. It proved to be a good indicator for the energy requirements of the organism.

Acetoacetates↗
PubMed1976

[Distribution of radioactivity in the body and rate of incorporation of radioactivity into the tissue proteins of monogastric animals following intravenous injection of tracer amino acids].

The studies were carried out with pigs and rats. The radioactive animo acids (14C leucine and 3H lysine) were administered to the pigs by way of a catheter tube into the jugular vein. Subsequently, the time pattern of the distribution of the specific amino acid radioactivity was followed in the TCE soluble and Tce precipitable fractions of the blood plasma (TCE= trichloro-acetic acid). The radioactive labelling in rats was carried out by injecting 14C leucine into the portal vein. The animals were killed after incorporation periods from 2 to 60 mins, and the levels of specific radioactivity were estimated in the TCE soluble and TCE precipitable fractions of the blood plasma, in the liver and in the skeletal muscles. The experimental results clearly indicated that the specific radioactivity of the tracer amino acids and the rate of incorporation of radioactivity into tissue proteins were greatly influenced by the size of the free amino acid pool within the range of distribution of the tracer. An estimation of the magnitude of the pool of free amino acids within the distribution range of the tracer can be obtained from the curve pattern for the decline of specific radioactivity of the corresponding free amino acid in the blood plasma. This pool exhibits a high rate of turnover. In all studies made to evaluate in vivo processes of protein synthesis by use of radioactive tracer amino acids it will be particularly important that consideration should be given to the specific radioactivity of the amino acid in the precursor pool for protein synthesis.

Amino Acids↗
PubMed1976

[Secretion of radioactively labeled amino acids into the digestive tract. I. Report 14C labeling of the pancreas after subcutaneous injection of 14C-leucine in rats].

4 different groups of experimental animals (rats) were injected 14C leucine at 4 different levels of specific 14C activity. Groups A and B received a dosis of leucine corresponding to the daily leucine requirements of the animals. The specific 14C activity was high in group A and low in group B. Groups C and D were injected a leucine dosis at a level of 10% from the groups A and B. the specific 14C activity being again high (group C) or low (group D). The results showed that a true evalution of the experiment could lnly be achieved if the values were related to the true rate of labeling (DPM/mg N or specific 14C leucine activity). The "percentage of the injected dosis" proved to be unsuitable for the analysis of the experimental results when taken as reference frame. The levels of specific 14leucine activity in free plasma leucine were in the same order as the specific activities of the injected solutions (C greater than A greater than D greater than B) whereas the order of specific 14C leucine activities in the TCE-soluble fraction of the pancreatic gland (TCE-trichloroacetic acid) was found to be A greater than C greater than B greater than D. This was due to the higher rate of 14C-leucine transfer into the protein fraction in the animals of group C and D receiving a normal supply of leucine. In these groups an equilibrium in specific 14C-leucine activity between the TCE-soluble and TCE-precipitable fractions was achieved 20-30 mins after injection. A relatively high degree of labelling of the pancreatic protein was noted as early as about 2 minutes after the injection of 14C-leucine. This indicates that in studies on amino acid absorption the secretion of those amino acids that are first absorbed and then resecreted via the pancreatic gland should always be taken into account.

Amino Acids↗
PubMed1976

[35S excretion in rats after injection of 35S methionine in relation to protein and amino acid nutrition].

Experimental rats received purified or semisynthetic diets containing 10% or 6% crude protein (Soya protein). These were supplemented with 0.1% or 0.2% L-, D- or DL methionine. After a 5-day feeding period the animals were injected 35S-DL-methionine. For 48 hrs after 35S administration the pattern of urinary 35S excretion was traced. Neither the level of protein does not the configuration of the methionine supplemented nor the level of methionine supplementation were found to influence urinary 35S excretion in any way. Amino acid imbalance as induced by supplementation of 5% DL threonine produced a highly significant increase in the rate of 35S excretion on the 1st day of experiment. The results obtained suggest the conclusion that any determination of methionine requirements based on metabolic data should leave out from consideration values on the level of urinary 35S excretion obtained on the first day of experiment, as these are dependent on amino acid transport rather than on protein metabolism.

Amino Acids↗
PubMed1975

[Protein evaluation based on intermediary protein metabolism criteria].

The activities of ornithine carbamyl transferase, arginase and glutamic-pyruvic transaminase increase in the liver of the rat if the biological value of the dietary protein decreases. Experiments with pigs revealed in the blood serum an analogous high correlation between the biological value of the dietary protein and the activities of arginase, glutamic-pyruvic transaminase, leucine aminopeptidase and glutamic-oxalacetic transaminase. The most favourable possibility of protein evaluation on the basis of criteria of the intermediary protein metabolism consists in the determination of the blood urea concentration provided that the protein carrier supply is standardized. This procedure which has been elaborated by BERGNER and co-workers in 1968 for the determination of the protein quality was confirmed by TAYLOR and co-workers in 1974 on healthy individuals as a reliable and elegant measuring technique with highly significant correlation. It is concluded that the true biological value of protein carriers or protein mixtures which are intended for human nutrition can on principle be determined only in studies with healthy individuals.

Alanine Transaminase↗
PubMed1975

[Influence of crude fibers in the diet of rats on the absorption of amino acids].

Growing rats received either a protein-free experimental diet or a diet containing 15% crude protein (whole egg). The crude fibre content of the diet was adjusted to 5%, 10%, or 20% by adding various proportions of what straw meal. Following a preliminary 7-day period of feeding the animals received L-14C-Leucine administered by stomach tube or by subcutaneous injection. In a 72-hour post-experimental period analyses were made to investigate the urinary and faecal excretion of radioactivity. About 50% of the amount of radioactivity excreted with the feaces were of endogenic origin. In general, higher percentages of straw meal in the diet produced higher levels of faecal 14C excretion. It was only in the animals placed on the whole egg diet that the TCA soluble portion of radioactivity was found to rise with the increasing straw content of the diet. The experimental results substantiate the assumption that native crude fibre influences the process of intestinal sloughing and, additionally, it is capable of abosrbing or adsorbing amino acids, peptides or protein, due to its spatial configuration. Similarly, it affects the digestion and resorption of proteins.

Amino Acids↗
PubMed1975

[Studies on the 14C-15N-acetamide turnover in sheep. 1. Studies on the 14C turnover].

4 male sheep (average weight: 53.5 kgs) were fed a semisynthetic diet containing acetamide as sole source of nitrogen. At the beginning of the trial twin-labelled 15N-14C-acetamide was administered by way of a ruminal fistula. The curve pattern of 14C activity in the TCE-soluble fraction of the ruminal fluid showed a synchronous behaviour in all animals beginning at 3 hours after the beginning of the trial. A half-life of 2 1/2 hours for the rate of absorption of 14C acetamide and deaminated 14C acetate was established from the decline in 14C activity observed in the TCE-soluble fraction of the ruminal fluid. The peak level of 14C labelling in ruminal proteins was reached after 6 hrs. The specific 14CO2 activity in respiratory air reached its maximum level after 4 hrs, and was then found to decline continuously. 56% of the administered amount of 14C was excreted over a period of up to 50 hrs after beginning of the trial. The very fact that the peak level of 14C activity was observed to appear in the TCE-soluble fraction of the blood plasma as early as after 1 hr seems to indicate that acetamide is also absorbed through the ruminal wall. The half-life of decline in the 14C activity of this fraction was 5.7 hrs. Analysis by thin layer chromatography showed that 75% of this amount of activity is present in 14C acetamide. The rate of 14C incorporation into blood plasma proteins reached a plateau region after 21 hrs, which was also maintained on the 2nd day of the experiment. 6.5% of the administered amount of 14C activity was excreted in the urine until the 7th day of experiment. 76.6% of the amount of urinary 14C activity excreted within a period of 48 hrs were voided as 14C acetamide. 3.8% of the administered amount of 14C activity was excreted with the faeces within the first 6 days of experiment.

Acetamides↗
PubMed1975

[Studies on the 14C-15N-acetamide turnover in sheep. 2. Studies on 15N turnover and comparative studies on the 14C turnover].

Three fistula sheep with average weights of 52.2 kgs were given 37.9 g of 15N and 14C labelled acetamide (= 1.09 mg 15N' and 0,95 mCi14C) which were administered directly through the fistula. The half-life period of 15N retention in the ruminal fluid (TCE soluble portion) was found to be 4 hrs. 18 hrs after 15N administration increasing amounts of 15N were carried back to the rumen by way of the rumino-hepatic circulation. The 15N concentration in the blood (TCE soluble portion) rapidly increased up to a peak value and, from 3 hrs after isotope administration, the 15N concentration was found to decline continuously, with a slight discontinuation at about the 10th hr of experiment. The rate of 15N incorporation into the protein fraction (TEC soluble portion) of the blood was delayed by 4 hrs, relative to the rate of 15N incorporation into ruminal proteins. An average of 43.1% of the administered amount of 15N was excreted in the urine within 7 days. Up to the 4th day of experiment the half-life period of urinary 15N excretion was 19 hrs. An average of 15% of the administered total amount of 15N was excreted in the faeces. In this process, the peak values in both TCE fractions were observed to occur on the 2nd day of experiment. The proportion of isotope in the TCE soluble fraction was found to increase continuously compared with the total amount of the isotope excreted in the faeces. Isotope concentrations between 0.03 and 0.13 atom% of surplus 15N were found in organ and muscle tissues of a sheep that had been slaughtered 7 days after administration of the isotope. The results obtained are discussed on the basis of comparisons made with the analogous behaviour of 14C activity.

Acetamides↗
PubMed1975

[Resorption and incorporation of radioactive labeled amino acids during administration of various protein carriers in rats. 1. Resorption of 14C leucine and 3H glycine after intragastric administration].

Male Albino rats (90-100 g) were fed ad libitum (with limited periods of feeding) for 14 days. The diets were adjusted to a crude protein content of 10%. Powdered whole egg, fish meal, yeast and gelatine were used as protein sources. Additionally, one group of rats was fed a protein-free diet. On the 15th day of experiment the rats were fed a test diet at a level of 2 g per 100 g of body weight. 2 hrs after that the rats received 25 muCi of 3H glycine and 5 muCi of 14C-L-Leucine per 100 g of body weight administered by way of intragastric infusion. It was found that a large proportion of the radioactive amino acids were absorbed as early as after 0.5 hr. The highest rate of absorption was observed in animals fed dietary proteins of poor quality or a protein free diet, so that in animals receiving a gelatine diet or a protein-free diet only 68.4% or 56.4% of the administered amount of 14C activity were detected inside the gastro intestinal tract after 0.5 hr. Analogous data for the 3H activity were 52.4% and 25.3%. Maximum absorption occurred after 3-7 hrs. Following this the level of radioactivity in the intestinal contents again increased reaching a peak value after 14-24 hrs; in the case of 14C activity this peak value amounted to 25.4% of the administered dose in animals fed the gelatine diet and 32.8% in the group receiving the protein-free diet. It was established that the major proportion of the resecreted amount of 14C activity was present in leucine. Until 72 hrs after the intake of 14C activity the level of radioactivity was again found to decline, a processes which was induced by processes occurring in the large intestines. Moreover, evidence was obtained in confirmation of previous findings, indicating that the composition of faecal amino acids was constant and unaffected by dietary proteins.

Animal Feed↗