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In the first part of this paper methodological aspects of intracellular amino-acid analysis in three species of animals, i.e. in rats, rabbits, and cats are dealt with. The genetic homogeneity as well as the age of the animal groups, metabolic differences between carnivores and herbivores, the length of the intestine and, thus, the time elapsing before the postabsorptive state is reached, furthermore, the body size which, in studies with muscle biopsies, makes correlated samples either possible or impossible; all these factors are experimental variables potentially affecting the evidence of the results obtained. Amino acids being involved in ammonia detoxification or showing raised plasma levels in hepatic failure form the subject of the subsequent parts of this paper. In the muscle cells of the three above species investigated after an overnight fast, the concentration of glutamine was about 5.5 times and that of glutamate about 4.1 times higher than in human muscle. Regarding glutamine and glutamate, there were no marked differences between the three species. As to the other amino acids measured in the rats, rabbits, and cats, alanine, the branched-chain amino acid (BCAA) as well as methionine and phenylalanine had intracellular values similar to those observed in humans. To test the hypothesis that ammonia lowers the BCAA plasma levels by considerably increasing glutamine synthesis and decreasing the intracellular glutamate pool with consecutively intensified transamination of BCAA for partial replenishment of this pool, we infused ammonium salts and created portocaval shunts in animal experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

In this paper preventive liver protective agents for the prophylaxis of hepatopathies due to functional stress, and curative protective agents for therapy of existing liver damage are distinguished. Preventive liver protective agents are key substances in the metabolism of proteins, carbohydrates, lipids, and sulfur. For curative liver protective agents, inhibitors of RNA and protein synthesis, calcium antagonists and inhibitors of sulfhydryl (-SH) containing enzymes are proposed and substantiated.

Described in this paper are ileocecal cannulation and ileorectostomy, two methods used for quantitative collection of chyme in the context of protein assessment on the basis of prececally absorbable amino acids. Reference is made to the manufacture of new, flexible intestinal cannulas of biocompatible material and to the surgical approaches in connection with either method. Determination of prececal digestibility of crude nutrients and absorption of amino acids in three rations fed to pigs with ileorectal anastomoses and ileocecal cannulas gave identical data or fair agreement with the extension of two amino acids. The conclusion was drawn that data recorded by means of the two methods can be used in the preparation of tabulated values.

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.

In continuation of our studies on the use of pig manure in ruminant feeding, the present paper is concerned with the investigation of the effects of solids from semi-liquid pig manure as ration components on the crude nutrient and amino-acid contents of the longissimus dorsi muscles of bulls, heifers and calves from experimental and control groups each including 6 animals. There was no difference in the crude protein, pure protein and crude ash contents between the control and the experimental groups. On the contrary, the data on dry matter and crude fat in the longissimus dorsi muscle were significantly lower in the experimental animals than in the control animals. This difference is explained by the fact that the energy content of the experimental ration (containing solids from semi-liquid pig manure) is lower than that of the standard ration. The results obtained from the analysis for 17 amino acids show that the change in amino-acid content of the muscle protein is not determined by the use of solids from semi-liquid pig manure.

In the present paper regression techniques were used for determing the true digestibility of amino acids from lysine-supplemented rations fed to laying hens as compared with unsupplemented rations of the same composition. 5 groups of 4 hens each were investigated receiving graded amounts of food and nutrients. The daily amounts of pellets fed per bird in group 1 to 5 were 120 gms, 100 gms, 80 gms, 60 gms and 40 gms. The quantity of lysine contained in 100 gms of the pellets was 664 mg in ration 1 and 554 mg in ration 2, the corresponding N values being 2.57 gm and 2.62 mg. The total amount of endogenic amino acids excreted per day was 128 mg per kg of body weight in birds receiving the lysine-supplemented ration and 132 mg per kg of body weight for the lysine-deficient ration. Data for the true digestibility of lysine and isoleucine were significantly higher in the case of the lysine-supplemented ration than with the lysine-deficient mixture. Lysine values were 86% and 75%, the corresponding lysine data in crude faecal proteins 4.8% and 7.1%. Generally speaking, the crude faecal protein of hens fed the lysine-deficient diet contained higher proportions of most of the essential and non-essential amino acids.

A survey is given of the alimentary ingestion, metabolization and elimination as well as of the biological significance of thiocyanate (SCN-) in the mammalian organism. SCN- is an important nutritional factor since it influences essential bodily functions, e.g. immune response. Its analytical determination in vegetable and animal foodstuffs may be considerably affected by the reversible binding of SCN- to protein molecules and by natural products, e.g. amino acids and cyanide, from glycosidic precursors, which interfere with the reaction with bromine. This will be combining paper chromatography with gas chromatography. Except Brassica species which are relatively high in SCN- in glycosidic combination, vegetable foodstuffs contain nearly 0.1-1.3 mg SCN-/kg fresh material; animal foodstuffs, e.g. beef, contains 0.5-0.7 mg SCN-/kg. Balances calculations have shown that in non-smokers the average alimentary ingestion ranges from 1.8 to 5.2 mg SCN-/d.

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.

The tetrazonium coupling reaction using Fast blue salt B and the sodium salt of 6-hydroxy-naphthalinsulfonic acid-(2) serves as a method for histochemical demonstration of proteins. Fast blue salt B reacts with histidin, tyrosin and in a slighter extent also with tryptophan. It is shown in this paper, that the histochemical tetrazonium reaction carried out under the optimal conditions is a specific staining for proteins and highly reproducible. The maximum of absorption at lambda = 530 nm of the azo dyes generated by the coupling reaction followes the Lambert-Beer's law. Nucleic acids as well as protein-SH-groups do not react with Fast blue salt B under the conditions described. Due to the exact reproducibility and specifity the tetrazonium coupling reactions seems to be a suitable method for at least comparative, microspectrometric protein determination within one species of cells.

The law protein nutrition of the nursing rat inhibits the growth of the new born rats. A percentage reduction of the dry substances by decrease of N2-free substances takes place. In relation to g dry substance the body protein content, collagen also, rises. Absolutely, these parts rest unaltered, just so the relation of the parenchymatous protein to collagen. The often support of view that starving provokes a collagen formation of the body, that means an exceed of the framework, can not be confirmed. Though in this paper we can give an explanation for the occurrence of this conclusion. Long interuptions of lactation periods remarkably have no effect on the growth and on the amin compartments of the body of new born rats. Only tryptophane is reduced in favour of the serine-fraction in the body of those animals. We discuss this finding as a change of the metabolisme of tryptophane depending of stress.

Application of chlortetracycline in rats resulted in the occurence of certain peptides in the blood-serum, which could not be detected in the serum of an untreated control group. These results were obtained by means of high voltage electrophoresis and paper electrophoresis of the serum of rats which was analyzed 1,3, and 13 hours respectively after a single dose of 50 mg chlortetracycline per 100 g body weight in comparison to an untreated control group. The new peptides could be found in the slight alkaline range 1 and 3 hours after application of chlortetracycline and in the strong acidic area of the electrochromatogram 13 hours thereafter. A more detailed investigation of the new peptides could demonstrate that the number of the following amino acids was reduced in the peptide chains after chlortetracycline: leucine, valine, serine, arginine, and lysine. On the other hand, amino acids, such as citrulline, sarcosine, alpha-aminobutyric acid, and ornithine, could be found which are normally not present in proteins.