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Biomedical subjects

G Allegri

Publications and source records attributed to G Allegri.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

Studies on the tryptophan load test in man.

Studies on the tryptophan load test were carried out by measuring the urinary excretion of 10 tryptophan metabolites via the kynurenine pathway in 25 healthy men and 20 women after oral L-tryptophan loading with dosages of 2 g. 50 mg/kg or 75 mg/kg body weight. With increasing doses of the amino acid, a difference was found between the male and female groups in the pattern of excretion of the tryptophan metabolites. In both groups, kynurenine and kynurenic acid were the metabolites excreted in the greatest amounts. The results indicate that the most useful loading dose of L-tryptophan for both men and women is 50 mg/kg body weight, as with 2 g L-tryptophan the excretion of the metabolites is too low and varies too much between the two groups of male and female subjects. On the other hand, the load with 75 mg/kg body weight can cause an overloading, particularly in women. No significant variations in the levels of the metabolites were found in the urine of two female subjects at different stages of the menstrual cycle after loading doses of 2 g and 50 mg/kg body weight. On the basis of the determination of the serum tryptophan levels, the period of urine collection was established as 10 h.

Adult↗
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Tryptophan, copper and zinc in hair of healthy subjects. Correlation with differences in hair pigmentation.

Tryptophan, copper and zinc levels were determined in the hair of 300 healthy subjects divided by sex, age and hair colour. Sex influences tryptophan content in hair, the levels of this amino acid being higher in males than in females. Tryptophan is also higher in infancy (2-5 years) and in both males and females aging around 80 years and over. Hair colour also influences tryptophan levels, which increase from fair to black hair. Copper levels are similar in hair of both males and females, while those of zinc are higher in women. Age influences the distribution of these two metals in human hair. Copper contents in hair of males are higher at the age 20-40 years. In females, values decrease over the age of 60 years. Instead, zinc levels are higher between 20 and 60 years in males, and between 13 and 19 years in females. As regards hair colour, copper is slightly higher in black hair in males and in fair hair in females, and lower in white hair in both sexes. Zinc values appear to be higher in red and lower in white hair in males. In females they are higher in black hair.

Adolescent↗
PubMedDate not supplied

Cerebral tryptophan metabolism in humans in relation to malignant pain.

The authors investigated the cerebral metabolism of tryptophan in patients suffering from malignant pain by means of CSF dosage of tryptophan (Trp), 5-hydroxytryptophan (5-HTP), serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA). The level of 5-HIAA in patients with pain was 66.48 +/- 13.67 ng/ml, while in those without pain was 25.05 +/- 13.25 ng/ml; the difference was statistically significant, p = 0.001. Trp, 5-HTP and 5-HT levels did not register significant differences in the two groups of patients, although a tendency to lower values was seen in patients with pain, supporting the hypothesis of increased turnover of this metabolic pathway in cancer patients. A statistically significant inverse correlation was also found between cerebral Trp levels and pain levels measured on the Scott-Huskisson visual analogue scale. The data obtained confirm the importance of the cerebral serotoninergic pathway in pain modulation and the interest which CSF analysis may have for the assessment of patients suffering from pain.

Aged↗
PubMedDate not supplied

Effects of two different loading doses of L-tryptophan on the urinary excretion of tryptophan metabolites in rats, mice and guinea pigs. Correlation with the enzyme activities.

The effect of two different loading doses of L-tryptophan (0.5 and 1.0 g/Kg b.w.) on excretion of tryptophan metabolites and the relation to the enzyme activities were studied in rats, mice and guinea pigs. In rats there is no ratio between the dosage used and the levels of the metabolites excreted. Doubling the amount of tryptophan administered, a 5-fold increase in the elimination of the metabolites along the kynurenine pathway is obtained. The 1.0 g/Kg load provides a more complete pattern of the metabolites than with the 0.5 g/Kg b.w. load. Kynurenic acid, kynurenine and xanthurenic acid are the chief metabolites excreted. In mice, the urinary excretion of the metabolites is very low with both loads. In guinea pigs, xanthurenic acid is excreted in the highest amount and kynurenic acid and kynurenine also constitute the large fractions with both loadings. The load of 0.5 g/Kg b.w. is preferable to that of 1.0 g/Kg b.w. for not causing B6-deficiency. Liver tryptophan pyrrolase exists in two forms in rats, while in mice and in guinea pigs it is present only as holoenzyme. This enzyme is more active in rats than in the other two species of animals. Kynureninase activity is lower in guinea pigs, but it apparently correlated to the low levels of excretion of the metabolites following this step. Kynurenine aminotransferase is very active in rats and in mice, while it is apparently depressed in guinea pigs, in contrast with the high excretion of xanthurenic and kynurenic acids, that puts in evidence a B6-deficiency. The excretion of tryptophan metabolites and enzyme activities are better correlated in rats.

Animals↗
PubMedDate not supplied

[Serum levels of total and free tryptophan in the premature newborn infant treated with aminophylline].

Apnea of prematurity in the majority of the cases becomes evident during the nonREM phases of sleep. Aminophylline, one of the most commonly used xantines in prevention, seems to reduce the incidence of these crises, increasing the duration of the REM phase and of the wakefulness of the newborn. It is possible that the serotonin, neuromediator of the REM phase, represents an important element in determining the crises of apnea, conditioned by variation in the serum levels of tryptophan that regulates the synthesis and liberation of cerebral serotonin. Our data demonstrate how aminophylline increases the post-natal physiological diminution of total tryptophan in the preterm. Therefore we can deduce, from our results, that an increased synthesis and liberation of serotonin may to increase the duration of the REM and to reduce the incidence of apnea.

Aminophylline↗
PubMedDate not supplied

Metabolites and enzyme activities involved in tryptophan metabolism in two different strains of mouse.

The urinary excretion of the tryptophan metabolites along the kynurenine pathway and the variations of enzyme activities involved in the degradation of tryptophan have been studied in two strains of mice. The total excretion of the metabolites was significantly higher in the strain of albino N.C.L. than in Swiss albino mice, in accordance with the higher activity of tryptophan pyrrolase, which was present only as holoenzyme. In both strains kynurenine, kynurenic and xanthurenic acids were excreted in larger amounts. However, the albino N.C.L. mice excreted a large amount of xanthurenic acid, not correlated with the slightly higher kynurenine aminotransferase activity observed in this strain. The very high excretion of this metabolite indicates that the load of tryptophan causes a B6-deficiency. Liver kynureninase activity was similar in both strains. Correlation between total urinary excretion of the tryptophan metabolites and enzyme activities appears in the same strain of mice, even though differences are present in different strains.

Animals↗