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Biomedical subjects

J Mauron

Publications and source records attributed to J Mauron.

At least 19 recordsLinked to original sources
PubMed1991

Selection of carbohydrate to protein ratio and correlations with weight gain and body fat in rats allowed three dietary choices.

In order to determine the spontaneous macronutrient choice of a normal rat population, we allowed growing animals to choose their food among three isocaloric diets: 5% protein - 40% carbohydrate; 45% protein - 40% carbohydrate and 5% protein - 70% carbohydrate, and we measured macronutrient intake, carbohydrate to protein (C/P) ratio and weight gain twice weekly during 9 weeks. At the end of the study, final body weight gain and fat accretion as well as brain serotonin content were measured. Protein consumption increased and fat intake decreased steadily during the assay (from 18.8 to 29 kcal% vs. 35.7 to 25.2 kcal%) whereas carbohydrate consumption remained constant (approx. 46 kcal%) ("carbohydrate homeostasis"), and as a consequence the C/P ratio dropped. There were great variations in total protein consumption between animals (13-32 kcal%) and an inverse relationship with fat intake because carbohydrate consumption was constant. Daily weight gain was negatively correlated with the corresponding C/P ratio, as were final weight gain and body fat content with the global C/P ratio characterizing the food choice of each rat. The concentrations of brain serotonin and 5-hydroxyindole acetic acid were rather uniform and did not show any correlations with any of the other variables. The percent food protein chosen by the animal determined the outcome of the trial at 9 weeks, i.e. food intake, weight gain and body fat accretion. In this experimental model, body fat accumulation is, therefore, directly linked to the protein content of the diet, inversely proportional to the fat level and not related to the carbohydrate content. Since the animals increase the proportion of protein in their food with age above basic nutritional requirements, it is postulated that the macronutrient choice of the rat is also determined by the need of the brain for a proper and balanced supply of neurotransmitter precursors adapted to the situation of each animal.

Adipose Tissue↗
PubMed1990

Influence of processing on protein quality.

In the first part the reactions and interactions of protein with macroconstituents of our food during processing are exposed from the chemical point of view. The reactions involving only protein (formation of isopeptides, of lysinoalanine, racemization) and the interactions with carbohydrates (Maillard reaction), oxidized lipids and polyphenols are briefly presented. Emphasis is put on the Maillard reaction since it is the most frequent reaction occurring during food processing and storage. The key compound rendering lysine unavailable in processed and stored foodstuffs in N epsilon-fructoselysine (FL). Its oxidative degradation product, N epsilon-carboxymethyllysine (CML) is found in variable but significant amounts in heat processed proteins. An interesting newer finding is that tryptophan can participate in a Maillard reaction with its indole-NH-group. In the second part an overview is given on the impact these reactions have on the two components of protein nutritive value, namely digestibility and biological value. Again, most examples will be related to the Maillard reaction. Protein digestibility may be reduced by the modification of the protein molecule (blocking of active amino acid side-chains, establishment of crosslinks) or by the formation of compounds that inhibit digestive enzymes. (Inhibition of aminopeptidase by an advanced Maillard derivative of lysine). Biological value may be diminished by the loss of essential amino acids and/or their reduced specific availability. Ion-exchange chromatography of the protein hydrolyzate is the method of choice to determine amino acid losses. It also provides some clues for the type of processing damage by the presence of unusual amino acids in the chromatogramme (e.g. furosine, lysinoalanine). Global amino acid bioavailability is defined. It is of a complex nature and can only be truely determined in a bioassay in the animal. Specific availability of an amino acid is linked to particular structural features. Thus, specific lysine availability is determined by the presence of a free or "reactive" epsilon-amino group. This is the basis for the analytical methods for available lysine. In the third part, the practical application of this knowledge to processed foods is shown using milk and vegetable protein as examples. Figures for the reduction in available lysine (blocked lysine) in different milk products processed according to conventional procedures are given and discussed. More subtile effects of milk processing on milk digestibility and stomach emptying are mentioned. The effects on protein nutritional value of extrusion-cooking of legume seeds and cereal flours are, then, presented.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1983

Is the adult protein-energy malnutrition syndrome the same as that described in the infant?

Protein-energy malnutrition, a multi-factorial disease, has been described predominantly in the infant. It was the aim of this research to give a biochemical assessment of the adult form and to compare it to the infantile syndrome within the same socio-cultural context of central Zaïre (Kwilu region). Thirty-four children, 22 women and 2 men suffering from marasmic kwashiorkor at the hospital of Yasa-Bonga (Kwilu) were submitted to a complete set of 7 anthropometric and 60 biochemical tests. The control values were taken from healthy well-fed children and adults from Yasa-Bonga; for certain parameters, rural adult control values were also obtained. Dyspigmentation was found in all patients, children and adults alike. The other symptoms were, in decreasing order of importance : oedema, dermatitis, apathy and liver enlargement, often accompanied by associated secondary pathology. In the children, all anthropometric indices were well below normal. In serum, total protein, albumin, prealbumin, ceruloplasmin and haemoglobin were reduced; the alpha 1, alpha 2 and beta-globulins were slightly reduced in infants but not much modified in adults, whereas gamma-globulins were slightly increased in adults only. IgG and IgM were increased in both infants and adults, the enhancement was less pronounced for IgA. Essential amino acids in serum were reduced in the patients and most non-essential amino acids raised, with the exception of tyrosine and arginine which were reduced like the essential amino acids. Some ratios (phenylalanine/tyrosine, serine/threonine, and non-essential/essential amino acids) proved to be very sensitive parameters for this type of protein-energy malnutrition. No differences were found in the amino acid levels between adult and infant patients, with the exception of alanine which was higher in the adults. Alanine levels were also high in the rural adult controls as compared to the European controls, probably due to the extremely high carbohydrate (manioc) diet. Serum electrolytes were normal in adult patients, with the exception of low Ca, whereas in children P and Mg were also low. Total lipids and cholesterol were reduced in adult and infant patients. The urinary excretion of all parameters measured (N, urea, creatinine, hydroxyproline, electrolytes, trace elements and some vitamins) was reduced in the patients with only small differences between adults and infants.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1983

Biochemical study of malnutrition. Part VI: Histidine and its metabolites.

The present study, as a part of a broader investigation on protein-energy-malnutrition (PEM) in rural Zaire, was undertaken in order to clarify varying aspects of histidine metabolism in patients suffering from protein-energy malnutrition (PEM). Measurement of histidine and its derivatives was performed on blood samples, in urine and in stool ultrafiltrates of healthy rural controls, of PEM mothers and PEM children, before and during dietary treatment, and after histidine oral overloading. In stool ultrafiltrates, unusually high concentration of histidine and of three major catabolites (imidazoleacetic acid, imidazolelactic acid and imidazolepropionic acid) were identified, contrasting with undetectable levels of urocanic acid. On the contrary, very large amounts of urocanic acid may be recovered in the urine of PEM patients, especially in those characterized by very poor life expectancy. Urinary urocanic acid level thus appears as a very sensitive indicator of liver malfunction, in a manner similar to low plasma prealbumin and/or high A-alpha 1-gamma-glutamyltranspeptidase values. These findings point to the severe impairment of histidase and urocanase, two enzymes regulating the histidine catabolic pathway. Under appropriate refeeding, all biochemical abnormalities described in surviving PEM patients are reversible. The persistence of high urinary urocanic acid excretion indicates a worsening of the patient's condition.

Adult↗
PubMed1982

Phosphatidyl choline and avoidance performance in 17 month-old SEC/1ReJ mice.

Male SEC/1ReJ mice aged 6 or 17 months were fed diets containing 0, 2, 4, and 8% added phosphatidyl choline. After 4 days on the test diets they were given 5 daily sessions of 100 trials each in the shuttle-box. The younger mice rapidly acquired an avoidance response and reached high, stable levels of performance. The older mice learned more slowly and reached significantly lower performance levels (p less than 0.01). Phosphatidyl choline had no effect on performance of young mice, while in the older mice the highest dose level of phosphatidyl choline increased avoidance performance by nearly 30% (p less than 0.05).

Aging↗
PubMed1981

Biochemical study of malnutrition. Part V. Metabolism of phenylalanine and tyrosine.

In order to elucidate the metabolic disorders which were observed for phenylalanine and tyrosine in protein-energy malnutrition, loads of both these amino acids were given to young mothers who showed all the clinical and biochemical symptoms of malnutrition and to healthy controls of the same age. Loads of phenylalanine resulted in higher blood levels, lower blood tyrosine formed from phenylalanine and higher urinary excretion of secondary phenylalanine and tyrosine metabolites in the patients, the former being due to a phenylalanine hydroxylase deficiency, the latter to concomitant disturbances in tyrosine catabolism. Loads of tyrosine resulted in very high urinary excretion of secondary tyrosine metabolites in two patients, due to a p-hydroxyphenylalanine-oxidase deficiency and to a high urinary excretion of tyrosine but almost normal excretion of secondary metabolites in the third patient, which is very likely to be due to a tyrosine-transaminase deficiency. Blood tyrosine levels remained lower in all patients, which may be explained by tyrosine malabsorption and increased utilization by the depleted tissues. Protein-energy malnutrition leads to enzyme deficiencies similar to those observed in some inborn errors of metabolism.

4-Hydroxyphenylpyruvate Dioxygenase↗
PubMed1981

Biochemical study of malnutrition. Part IV. Determination of amino acids in the serum, erythrocytes, urine and stool ultrafiltrates.

Before dietary treatment, no significant differences, except for alanine, were found in the amino acid pattern for 22 young mothers and 33 children with protein-energy malnutrition (PEM), the characteristic feature of the serum pattern being the imbalance between essential and non essential amino acids. Apart from lysine, the essential amino acid levels were all below normal. This imbalance may be detected readily from the abnormal values of some particularly sensitive ratios: phenylalanine/tyrosine, valine/glycine, non essential amino acids/essential amino acids and, above all, serine/threonine. A striking finding was the very low threonine levels in all subjects, including local controls and the extremely low tryptophan levels in malnourished children. Before treatment, almost all the erythrocyte amino acid levels as well as the E/S ratios (erythrocytes/serum) were found to be raised in 9 children, demonstrating their poor clinical status. The urinary amino acid level was similar in both, patients before treatment and local controls. The urinary threonine level was low, like in the serum. A normalisation in most of the amino acid levels in the serum was observed upon dietary rehabilitation although not yet significant in all of them. In urine a similar tendency was observed but it was significant for threonine and methionine only, after 2 weeks treatment. Some additional urinary amino acid assays revealed changes upon two weeks dietary rehabilitation that can be interpreted as an increased production of enzymes affected by PEM as well as a growth of the patients' muscular mass. Increased free amino acid losses in the stools, caused by diarrhoea due to secondary malabsorption, and various viral and bacterial infections accompanying malnutrition, illustrate the severity of the diarrhoea.

Adolescent↗
PubMed1979

[The problem of sugar resorption in the small intestine: histochemical studies by means of the Gomori method].

The role of alkaline phosphatase during active absorption of sugars is experimented with Gomori's histochemical method. Experiments on empty intestine show that the surgical intervention does not alter the phosphate content of the wall of the small intestine. Absorption experiments with 10% and 5,4% (isotonic) glucose solutions demonstrate a marked decrease in the alkaline phosphatase content of the wall of the small intestine. In half of the cases only, absorption experiments with a 10% mannitol solution determine a small decrease in the alkaline phosphatase of the wall of the small intestine. In 90% of the cases, there are lesions of the intestinal epithelium.

Alkaline Phosphatase↗
PubMed1978

N-Substituted lysines as sources of lysine in nutrition.

Twenty seven alpha-N- and epsilon-N-substituted derivatives of lysine belonging to eight different classes: (1) natural dipeptides, (2) alpha-N-acyl-, (3)epsilon-N-acyl-, (4)epsilon-N-(alpha-amino acyl)-, (5)epsilon-N-(omega-amino acyl)-, (6)alpha-N-epsilon-N-di-amino acyl-, (7)epsilon-N-acylglycyl- and (8)Schiff's bases were synthesized. The "in vitro" utilization of some of them was tested by a rat growth assay. Only the derivatives which provided biologically available lysine were hydrolysed by one or more of the intestinal mucosa, liver or kidney homogenates. It is argued that derivatives which can be split by any of the above homogenates are potential sources of lysine. The derivatives of classes (1), (4), (6) and (8) are nearly as efficient as free lysine while lysine in classes (2) and (7) is not utilized at all. From the classes (3) and (5) only some are utilized: epsilon- formyl- and epsilon-acetyl- partially and epsilon-(gamma-glutamyl)-totally. The biologically available derivatives were 4 to 7 times less reactive than free lysine in the Maillard reaction and could therefore be used to fortify foods which have to be submitted to severe heat-treatments. A cheap method of synthesis of epsilon-(gamma-glutamyl)-lysine is proposed and its metabolic transit described.

Animals↗
PubMed1978

Study on malnutrition. III. Biochemical assessment of the dietary treatment and evolution of the illness.

During the course of a malnutrition study, the efficiency of two diets has been followed by clinical observations and biochemical tests. The diets were adapted to the physiological state of 25 patients (16 children, 6 young mothers, 1 adolescent and 2 men) undergoing treatment in a rural hospital at Yasa-Bonga, Zaïre. One group of patients was examined after two weeks of treatment (6 children, 2 mothers), the other group after two months (8 children, 5 adults). In order to study the evolution of the illness, 9 children and 3 young mothers were examined regularly after the return to their villages every 6 months for 2-4 years. The patients responded positively to both diets. After two months of treatment they had clinically recovered, except for the most serious cases. After two weeks of treatment a deficiency in electrolytes, low levels of prealbumin and a net increase in transferrin were noted. After 2 months of treatment the children had regained their normal growth (hydroxyproline index), and most of the biochemical parameters had reached their normal value despite a few deficiencies in electrolytes, phosphorus and magnesium. However, the prealbumin level remained low, particularly amongst children suffering from relapses. In a few cases the activities of cholinesterase (CHE) and gamma-glutamyltranspeptidase (gamma-GT) remained low, which was taken as a sign of poor response to treatment. Generally, the adults responded more slowly to treatment than the children. Regular examinations carried out on certain patients on their return to the villages permitted 2 groups to be distinguished: the first one was composed of patients recuperating well due to good social conditions; the second group of patients suffered from relapses due to lack of hygiene and of rudimentary knowledge of nutrition, and above all severe social problems. The condition of the liver of all these patients was very important; it could be estimated by the determination of the serum levels of prealbumin and the activities of CHE, gamma-GT and isoenzymes of gamma-GT.

Adolescent↗