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Biomedical subjects

C Costa

Publications and source records attributed to C Costa.

At least 235 records · Page 13Linked 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↗
PubMedDate not supplied

Familial neonatal SIDS revealing carnitine-acylcarnitine translocase deficiency.

UNLABELLED: A patient with a severe phenotype of carnitine-acylcarnitine translocase deficiency (CATR)(McKusick 212138) is reported. Prior to birth, a defect in beta-oxidation was suspected because of neonatal death of six siblings. Dietary treatment during neonatal adaptation and the subsequent six months of life and a trial of carnitine supplementation are reported. The rapidity with which long chain fatty acid metabolites can accumulate and induce secondary carnitine deficiency within a few hours after birth in an infant with CATR is noteworthy. CONCLUSION: High rates of glucose suppressed neonatal lipolysis in this infant, but did not seem sufficient to avoid secondary carnitine deficiency as in severe forms of CATR. Therefore simultaneous use of insulin and glucose may be necessary to control neonatal lipolysis. Carnitine supplementation and the possible adverse effects of MCT systematically administrated, should be further assessed in patients with CATR.

Carnitine↗
PubMedDate not supplied

[Sensorineural hearing loss due to neonatal hyperbilirubinemia].

In this article, the sensorineural hearing loss is presented as a possible sequelae of neonatal hyperbilirubinemia. In our program of early hipoacusia detection, 241 babies were examined from January 1996 until November 1999; 7 cases had a history of hyperbilirubinemia in the neonatal period and 2 of them were diagnosed of sensorineural hearing loss. We discuss how the bilirubin or any other associated factor might have been the cause and this could explain the selective affectation of some children.

Algorithms↗
PubMedDate not supplied

Plasma cortisol and testosterone in hypercholesterolaemia treated with clofibrate and lovastatin.

Plasma testosterone and cortisol concentrations were measured in 32 familial heterozygous hypercholesterolaemic subjects, aged 40-45 years. The subjects were divided into two groups of 16, each containing eight men and eight women. The women had normal menstrual cycles. After a period on placebo, one group of patients was given 40 mg/day lovastatin and the other was given 1500 mg/day clofibrate. Both drugs significantly reduced the plasma cholesterol concentration, however, unlike clofibrate, lovastatin did not decrease plasma levels of testosterone and cortisol. The response to stimulation by adrenocorticotrophic hormone of plasma cortisol and urinary 17-hydroxy levels was significantly reduced by treatment with clofibrate, but unchanged by lovastatin. The different effects produced by the two drugs probably reflect different mechanisms and sites of action.

Adult↗
PubMedDate not supplied

The effect of oxygen on methanol oxidation by an obligate methanotrophic bacterium studied by in vivo 13C nuclear magnetic resonance spectroscopy.

13C NMR was used to study the effect of oxygen on methanol oxidation by a type II methanotrophic bacterium isolated from a bioreactor in which methane was used as electron donor for denitrification. Under high (35-25%) oxygen conditions the first step of methanol oxidation to formaldehyde was much faster than the following conversions to formate and carbon dioxide. Due to this the accumulation of formaldehyde led to a poisoning of the cells. A more balanced conversion of 13C-labelled methanol to carbon dioxide was observed at low (1-5%) oxygen concentrations. In this case, formaldehyde was slowly converted to formate and carbon dioxide. Formaldehyde did not accumulate to inhibitory levels. The oxygen-dependent formation of formaldehyde and formate from methanol is discussed kinetically and thermodynamically.

Alphaproteobacteria↗
PubMedDate not supplied

Impact factor in AIDS and other infectious diseases.

The impact factor (IF) is the most accurate system currently available for objectively evaluating the scientific productivity of individual researchers and institutions. It represents the quality level of a periodical and, at the same time, is a convenient reference parameter for the researcher to use in choosing an appropriate journal before submitting his own work for consideration. From this standpoint, we conducted an analysis of periodicals with the highest IF, including those strictly related to infectious diseases and HIV/AIDS, specialty journals, and general medicine reviews. This was done in order to determine just how much of these journals' total 1998 production consisted of articles concerning HIV infection and AIDS. This examination, conducted through a search of the MEDLINE database, predictably revealed greater interest in the HIV/AIDS topic among journals with the highest IF that focus on infectious diseases, though the same interest revealed when examining specialty journals and general medicine periodicals was not negligible.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Effects of noise on functional cardiovascular parameters: a follow-up study.

The aim of this follow-up design study is to give a contribution to the knowledge of the controversial relations between noise and functional cardiovascular parameters. The study population consisted of 757 male employees working for 5 different firms in the oil chemical area (refining and distribution of fuel) with different qualifications--345 workers, 212 drivers, 200 clerks--and thus exposed to 3 different levels of noise (85-90 dBA, 80-85 dBA and < 80 dBA respectively). Heart rate, systolic and diastolic blood pressure were monitored 3 days a week at the beginning of the working shift, for a period of 12 years. The analysis of the data obtained indicates that all the 3 parameters under observation tend to increase progressively with the age and working age of the subjects. In the comparison between the 3 levels of exposure, heart rate results not affected by the exposure to noise; systolic blood pressure results sensitive only for the discrimination of the effects due to exposure, showing a statistically significant difference only between clerks on one side and workers and drivers on the other; diastolic blood pressure is highly influenced by the level of exposure to noise, showing significantly different slopes for the 3 groups. In conclusion, blood pressure is a parameter definitely more reliable for the correlation to the level of exposure, while heart rate cannot be considered a marker of exposure to noise.

Adult↗
PubMedDate not supplied

[Descriptive epidemiology of ambulatory neurological care in the Vega Baja (Alicante) area].

AIMS: The aim of our work is to analyse ambulatory neurological care in the area of Vega Baja, which is located in the province of Alicante (Spain), in order to find out: a) the demographic characteristics of the population that visits the neurologist; b) the motives that led to the visit; c) the diagnoses carried out. PATIENTS AND METHODS: A prospective two year study of patients over the age of 14 sent to the Neurology department. The reasons for the visit were classified into 15 categories and the diagnoses were given a code according to the criteria set out in the International Classification of Diseases 9th edition. RESULTS: A total of 2,227 patients were included in the study. The annual incidence of first visits was 10.6 per 1,000 people. 60% of the patients were women. The average age was 51.6 years old. Headache was the most frequent reason for the visiting the doctor. One out of every three patients visited because of headache and/or facial pain. The five most frequent diagnoses in the under 65 group were, in descending order of frequency: migraine, tension type headache, epilepsy, syncope and anxiety. The five most common diagnoses in the over 65 group were, in descending order of frequency: Alzheimer, Parkinson, transitory cerebral ischemia, cerebral thrombosis and epilepsy. CONCLUSIONS: The type of ambulatory neurological pathology depends on the age of the patients, and thus we find that headache is prevalent in the younger patients whereas neurodegenerative and vascular pathological conditions are more common in those over the age of 65.

Adolescent↗
PubMedDate not supplied

Early events of experimental exposure to amorphous and crystalline silica in the rat: time course of surfactant protein D.

Pneumoconioses determined by chronic inhalation of different kinds of silica present with peculiar clinical and histopathological features. Silicosis, caused by crystalline silica, is characterized by typical fibrous parenchymal nodules. Less defined are pneumoconioses due to amorphous silica. Aim of current experimental research on silicosis is to investigate the early events that lead to nodular fibrosis of the lung. A secretory component of the pulmonary environment, surfactant, seems to be involved in silica toxicity; surfactant protein D is a protein constituent, apparently involved in the homeostasis of the phospholipid component. We studied the behaviour of SP-D 2, 12 and 24 hours after treatment with 200 mg/kg crystalline silica or pumice powder suspended in 400 microl/kg saline solution and instiled intratracheally to rats. Both immunohistochemical localization and immunoblotting quantification demonstrated a sensible increase in intracellular SP-D, localized in alveolar type II cells and some bronchiolar epithelial cells, 2 hours after treatment. Increment appears less marked 12 hours after administration, reaching again levels comparable to control at 24 hours. The behaviour of SP-D after pumice instilation is similar, but with a significantly minor increment at 2 hours. These results indicate crystalline silica as responsible for a stronger acute injury of pulmonary tissue.

Animals↗
PubMedDate not supplied

[Genotoxicity and activation of organophosphate and carbamate pesticides by cytochrome P450 2D6].

The role of the polymorphic cytochrome P450 (CYP) 2D6 isoform in catalysing the oxidative biotransformation of the organophosphate pesticide chlorpyriphos and the carbamate aldicarb into structures that inhibit cholinesterase and induce genotoxicity has been investigated in microsomal fraction, using quinine as a specific chemical inhibitor of CYP 2D6. Pesticides were incubated with rat liver microsomes and production of anticholinergic active metabolites was investigated by the inhibition of human serum cholinesterase. Compared to microsomes incubated without quinine, where cholinesterase activity was inhibited to a mean 53% (chlorpyriphos) and 57% (aldicarb) of control, the introduction of P450 2D6 inhibitor quinine into microsomal incubation mixture reduced cholinesterase activity to 72% of control for chlorpyriphos and to 27% for aldicarb, suggesting that P450 2D6 is involved in the activation of chlorpyriphos but does not influence aldicarb toxicity on acetylcholinesterase. Moreover, the potential genotoxicity of these compounds was evaluated by single cell gel electrophoresis (comet assay) on human leucocytes. DNA fragmentation compared to control was markedly increased after incubation with aldicarb plus quinine, confirming that the parent compound is more toxic than the products of CYP metabolism; conversely, DNA damage after incubation with chlorpyriphos was sensibly reduced by quinine indicating the metabolic activation of this pesticide by CYP 2D6. These data suggest that polymorphism of CYP 2D6 can influence the toxicity of organophosphate but not of carbamate pesticides.

Animals↗
PubMedDate not supplied

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↗