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Biomedical subjects

C Costa

Publications and source records attributed to C Costa.

At least 199 records · Page 11Linked to original sources
PubMed1980

Total and free tryptophan levels in serum of newborn infants. Relationships with the Serotonin and nicotinic acid pathways.

The levels of total and free serum tryptophan have been determined in a group of newborn babies at birth, one day later and five days after birth. Total and free tryptophan levels are very high in the umbilical cord at birth, decrease quickly and significantly 24 hours after birth and show a slight, but not significant increase five days after birth. The high tryptophan levels at birth and their decrease in the first day after birth recall previous data on tryptophan metabolism "via" serotonin and "via" nicotinic acid. Since the synthesis of cerebral serotonin depends on the availability of tryptophan, and is thus linked to the level of free tryptophan in blood, these data suggest that synthesis of serotonin as well may be elevated at birth and may reach the values of adult soon afterwards. With respect to the nicotinic acid pathway the high levels of tryptophan in blood may be related to the synthesis of tryptophan pyrrolase, which is present in the liver of newborn babies.

Female↗
PubMed1979

Tryptophan metabolism in animals with dermatitis. I) In Rats.

Tryptophan metabolism "via kynurenine" after load of amino-acid has been studied in urine of rats before and after induction of experimental light-conditioned dermatitis with psoralen. Tryptophan load in animals during the acute phase of dermatitis (one day after induction) causes a markedly increased urinary excretion of total metabolites in comparison with that obtained before dermatitis. After six days of dermatitis, when the skin damage was in repair, the excretory values after tryptophan load in rats are only slightly increased indicating that the metabolic disturbance is correlated with the skin damage.

Animals↗
PubMed1979

Tryptophan metabolism in animals with dermatitis. II) In guinea pigs.

Tryptophan load in guinea pigs after induction of a photodermatitis from psoralen caused marked increase of urinary excretion of total metabolites "via kynurenine" in comparison with that obtained before dermatitis. Xanthurenic acid is the metabolite which showed the most increased levels in urine during dermatitis. This dermatitis from furocoumarin caused an alteration of tryptophan metabolism in guinea pigs as well as rats, but species differences in the excretion of metabolites after amino acid load are observed.

Animals↗
PubMed1978

A further contribution to the choice of the dose for L-tryptophan load test.

The analysis of the results of a study on the urinary excretion of metabolites "via kynurenine" after the ingestion in man of different amounts of tryptophan is reported. Of the three doses of L-tryptophan administered to the subjects, that is 2 g pro capite, 50 mg/Kg and 75 mg/Kg body weight, it is preferable to choose that of 50 mg/Kg b.w. as a load test. Such a dose assures an excretion of the more important metabolites without significant variations between men and women and without producing overloading effects.

Aminohippuric Acids↗
PubMed1977

[Hyperosmolar coma in diabetes (author's transl)].

Diabetic hyperosmolar coma is characterized by the appearance of a diabetic metabolic state in middle age, lack of ketosis, osmolarity of the plasma greater than 350 milliosmoles, psychic and neurological disturbances, increased occurrence of secondary diseases, arterial thromboses, azotemia. The mortality is 30-60%. The pathogenesis is still uncertain in many respects, consequently the suggestions for therapy are varied. The authors have found the following procedure useful: rapid compensation of sodium deficit, restoration of water balance, normalization of the composition of body fluids by reference to continuous laboratory investigation.

Diabetic Coma↗
PubMed1976

Studies on the kynurenine adminotransferase activity in rat liver and kidney.

The kynurenine aminotransferase activity of supernatant and mitochondrial fractions obtained from rat liver and kidney was studied with L-kynurenine and L-3-hydroxykynurenine as substrates. A substrate inhibition with L-kynurenine at concentrations higher than 6-7mM was observed with all four enzyme preparations. This did not happen with L-3-hydroxykynurenine as a substrate. Moreover, the liver mitochondrial enzyme shows a Km for pyridoxal phosphate 2-4 times smaller than the other preparations when assayed with L-3-hydroxykynurenine as a substrate. Therefore, the accumulation of xanthurenic acid and not of kynurenic acid in B6 deficiency could be related both to this high activity of liver mitochondrial kynurenine aminotransferase with L-3-hydroxykynurenine, even at small concentrations of B6, and to substrate inhibition observed with L-kynurenine and not with L-3-hydroxykynurenine.

Animals↗
PubMed1976

Tryptophan metabolism "via" nicotimic acid in patients with scleroderma.

The tryptophan metabolism "via" kynurenine was studied in five patients with scleroderma after aminoacid loading. Four of these patients had abnormal tryptophan metabolism, characterized by a large urinary excretion of kynurenine and kynurenic acid in two cases, of kynurenine, 3-hydroxykynurenine and kynurenic acid in one case and of 3-hydroxyanthranilic acid in another case and generally a reduced excretion of xanthurenic acid and its 8-methyl ether in comparison with a group of healthy controls. Only two of the four patients had a normal response to tryptophan loading after pyridoxine administration, while no one of these responded to nicotinamide supplementation. But the simultaneous administration of pyridoxine and nicotinamide to three of these patients normalized the excretory picture after tryptophan loading. This suggested the presence of a combined vitamin deficiency in seleroderma. As four out of five patients showed total excretory values of kynurenine, kynurenic acid and acetylkynurenine higher than that of the controls, the sum of these values might be considered as a characteristic index of scleroderma.

Adult↗