The paramount importance of proteins in nutrition and biochemistry is becoming increasingly recognized. A substantial portion of all enzymes is protein; this protein moiety often needs an accessory food factor or sometimes a mineral as a co-enzyme. The well-known pioneering role of Sir Frederick Gowland Hopkins in the development of the knowledge of accessory food factors or vitamins, and of enzymology, justifies the inclusion of the subject of this contribution in the Symposium. Nutrition, often erroneously regarded as being synonymous with dietetics, is a vast and rapidly growing subject. In relating these two large fields, i.e. proteins and nutrition, there will be time only to summarize some observations made in the Medical Research Council’s Human Nutrition Research Unit on (i) the determination of the protein values of foods as eaten by man, in terms which can be directly and quantitatively related to the protein needs of individuals; (ii) the production experimentally in animals of syndromes resembling two main forms of protein-calorie deficiency encountered in human beings; (iii) a demonstration of congenital defects, particularly in the central nervous system, occurring in the offspring of mothers fed on protein-calorie-deficient diets; (iv) the probable importance of protein-calorie deficiency in the pathogenesis of disease.
SUMMARY An increased concentration of neuroglial cells was found in the spinal cords of dogs maintained from weaning on diets of low protein value. Most of the additional cells were perineuronal oligodendrocytes, but some activated astrocytes were present and there was an increase in the size and number of their fibres. The walls of the myelin sheaths were thinner than in age‐controls. During the more severe stages of the protein‐calorie deficiency syndrome (8–11 weeks of age), there was a loss of Nissl substance from the motor cells of the anterior horns and small changes occurred in the histochemical activity of the glutamic and succinic dehydrogenases. Changes in the basal ganglia and thalamus, although definite, were less marked, and in the cerebral cortex the changes were minimal. Only in the cerebellum was there any evidence of cell loss. Changes of similar type but greater severity were found in the congenitally malnourished pups and, in addition, there was a reduced number and concentration of nerve cells in the cerebral cortex. The morphological changes observed in the dogs are discussed in relation to clinical signs described in malnourished children. It is suggested that malnutrition during intrauterine and early postnatal life may lead to irreversible changes within the central nervous system. Resume Effets de l' insuffisance alimentaire en proteines et en calories chez le chien II. Changements morphologiques dans le système nerveux Une concentration accrue de cellules neurogliales a été trouvee dans la moelle épinière de chiens, maintenus à un régime appauvri en protéine et calories depuis le sevrage. La plupart des cellules supplémentaires étaient du type oligodendrocytes péri‐neuronales, mais quelques astrocytes actifs étaient présents; et il y avait une augmentation en taille et en nombre de leurs fibres. L'épaisseur des gaines de myéline était plus fine que chez les sujets contrôles du même âge. Au cours des périodes les plus sévères du syndrome de deaficience protéinique et calorique (8 à 11 semaines d'âge chronologique), on notait une perte des corps de Nissl au niveau des cellules motrices de la come antérieure et de légeres modifications dans les activités histo‐chimiques des déhydrogénases glutamiques et succiniques. Les modifications dans les noyaux gris centraux et dans le thalamus, quoique certaines, étaient moins marquées et au niveau du cortex cérébral les perturbations étaient minimes. C'est seulement au niveau du cervelet que l'on pouvait noter quelques pertes cellulaires. Des troubles identiques mais beaucoup plus sévères ont été trouves chez les chiots mal nourris depuis le moment de la naissance et de plus, on a trouve un nombré et une concentration de cellules nerveuses diminuées dans le cortex cérébral. Les changements morphologiques observés chez le chien sont discutés par comparaison avec les signes cliniques décrits chez les enfants insuffisamment alimentés. II est suggéié que le malnutrition durant la vie intra‐utérine et immédiatement post‐natale peut conduire à des modifica...
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