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Biomedical subjects

M Candito

Publications and source records attributed to M Candito.

At least 37 records · Page 2Linked to original sources
PubMed1995

Stability of 3,4-dihydroxyphenylacetic acid in plasma extracts assayed by high-performance liquid chromatography with electrochemical detection.

3,4-Dihydroxyphenylacetic acid (DOPAC) can be easily assayed by high-performance liquid chromatography (HPLC) with electrochemical detection at the same time as norepinephrine (NE), epinephrine (E), and dopamine (DA). The latter catecholamines are stable in perchloric acid extracts for over 6 h at 4 degrees C in the dark whereas DOPAC levels drop rapidly by more than 50% in 6 h at 4 degrees C in the dark. This study investigated the effects of reducing agents [ascorbic acid, dithiothreitol (DTT), reduced glutathione with or without a metal chelating agent (diethylenetriaminepentaacetic acid or ethylenediaminetetraacetic acid)] on DOPAC. Extracted with alumina using 0.65 mmol/1 DTT prior to HPLC and electrochemical detection, DOPAC remained stable in the perchloric acid extract for 2 h at 4 degrees C in the dark.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1995

Abnormal alpha-aminoadipic acid excretion in a newborn with a defect in platelet aggregation and antenatal cerebral haemorrhage.

alpha-Aminoadipic acid (alpha AA) is an intermediate in lysine metabolism. We report a new case with alpha AA excess in urine and plasma, without alpha-ketoadipic acid, in a full-term male child born to unrelated parents; he presented at 24h of life with seizures that failed to respond to phenobarbital, clonazepam, and Vigabatrin and death occurred on the 38th day of life. Brain imaging suggested antenatal haemorrhage. Small quantities of alpha AA were also detected in the blood and urine of both parents and a healthy brother, all three of whom exhibited the same defect in platelet aggregation as the deceased child. Both parents had decreased levels of plasma neopterin, a finding that might be related to the immunodeficiency described in other cases.

2-Aminoadipic Acid↗
PubMed1994

High-performance liquid chromatographic measurement of cerebrospinal fluid tetrahydrobiopterin, neopterin, homovanillic acid and 5-hydroxindoleacetic acid in neurological diseases.

Cerebrospinal fluid (CSF) samples from patients with a variety of neurological disorders were assayed to determine the concentrations of tetrahydrobiopterin (BH4), the active cofactor of hydroxylases. Dihydroneopterin (NH2) and neopterin (N), which are linked with BH4 synthesis and are inflammatory biochemical markers, were also measured simultaneously in a number of patients. 5-Hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA), the main products of serotonin and dopamine breakdown, were analyzed in parallel whenever possible. As BH4 and NH2 are difficult to analyze owing to their instability, CSF samples were collected under special conditions to preserve the reduced BH4 and NH2. Liquid chromatographic assays and detection of the various substances measured also required particular precautions. BH4 concentrations were elevated in patients with neurological disorders such as syphilis and lupus-like disease and especially in an AIDS patient with neurological complications with an increased N/BH4 ratio.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Plasma catecholamine levels in children.

While blood norepinephrine and epinephrine levels are well established in adults, literature data concerning concentrations in young children are conflicting. This situation prompted us to assay plasma catecholamines in 86 healthy subjects aged two days to fifteen years using a sensitive high-performance liquid chromatography technique with electrochemical detection. Norepinephrine and epinephrine concentrations remained elevated up until 24 months of age, then dropped progressively to adult levels between 24 and 36 months, with fluctuations. These fluctuations, which reflect the sensitivity of children to environmental factors, prevented demonstration of any catecholaminergic secretory abnormality by blood assays in subjects under two years of age. Urinary assays, for which established values exist, are the only applicable procedure in such patients.

Adolescent↗
PubMed1993

Simple column liquid chromatographic assay for serum neopterin.

A simple high-performance liquid chromatographic assay for serum neopterin with highly sensitive fluorimetric detection (limit 1 nM) is proposed. Comparison with results obtained by radioimmunoassay revealed a good correlation between the two techniques. The potential use of this method for the follow-up of liver transplant patients is discussed.

Adult↗
PubMed1993

Hemodynamic effects of prolonged enoximone infusion (7 days) in patients with severe chronic heart failure.

This study investigated the hemodynamic effects and tolerance of infusion of 10 micrograms/kg/min enoximone over 7 days in 12 patients (mean age 64.3 years) with severe chronic heart failure (10 NYHA Class III and 2 Class IV) with idiopathic dilated cardiomyopathy. Hemodynamic parameters were measured 10 minutes, 3 hours, 6 hours, 18 hours, 24 hours, and 7 days after the start of infusion. Catecholamines were assayed before the start of the infusion and on day 7. The heart rate increased on an average from 90.8 +/- 13.7 before infusion to 108.5 +/- 8.2 beats/min (p < 0.05) on day 7 (+20%). The mean arterial pressure decreased by approximately 10% (p < 0.05) between the start and end of the infusion. The pulmonary artery diastolic pressure dropped by a maximum of 30% at the 24th hour (23.1 +/- 5.1 to 16 +/- 5.4 mm Hg; p < 0.01). This decrease remained significant on day 7; the index cardiac was increased a maximum of 40% between the 18th and the 24th hour; p < 0.01). This increase was still significant on day 7 (2.35 +/- 0.44; p < 0.05; +22%). Finally, the decrease in systemic arterial resistance, which reached a maximum of 30% of the 24th hour, persisted on day 7 (-22%); 2076 +/- 451 to 1612 +/- 283 dynes/sec/cm5; p < 0.05). The norepinephrine level did not change significantly (4.5 +/- 1.2 nmol/l before infusion vs. 4.2 +/- 1.1 nmol/l on day 7). Infusion had to be stopped in one patient after 30 minutes because of prolonged severe hypotension.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

5-Methoxypsoralen: effect on the noradrenaline circadian rhythm of sleep-deprived subjects.

5-methoxypsoralen (5-MOP), a serotonin analogue, stimulates the secretion of melatonin, which plays an important role in circadian rhythm regulation. Melatonin production is essentially controlled by noradrenaline (NA). To investigate the effect of 5-MOP on the 24 hr NA rhythm, hourly plasma NA concentrations measured over 24 hr in 7 healthy young subjects who took 40 mg 5-MOP orally at 21:00 hr the evening before were compared with values obtained in drug-free subjects. All subjects were sleep-deprived and under conditions in which sympathetic nervous system activation was repeated every hour over 24 hr. In both series of patients, a significant difference was observed between mean morning values and mean night values, reflecting persistence of a circadian rhythm. In subjects given 5-MOP, a significant difference was also observed between mean afternoon values and mean night values. However, MANOVA analysis failed to find any difference between the two series of subjects. Acute administration of 5-MOP thus had no significant effect on the NA circadian rhythm under our study conditions.

5-Methoxypsoralen↗
PubMed1993

Tryptophanemia and tyrosinemia in adolescents with impulsive behavior.

Tryptophan (TRP) and tyrosine (TYR), respectively the circulating precursors of the central serotonergic (5-HT) and catecholamine systems, were measured in eight adolescents with impulsive behavior regardless of the exact type of disorder. The 6 week study period included weekly blood sampling and clinical evaluation. The ratios of TRP and TYR to large neutral amino acids (LNAA), which indicate the availability for the synthesis of neurotransmitters, were calculated. Comparison of results with eight hospitalized controls of the same age (12.5 to 18 years) revealed lower total TRP levels in four adolescent patients, a lower TRP/LNAA ratio in three adolescents, and a lower free TRP concentration in six adolescents with discretely enhanced albuminemia. A slight increase in TYR and the TYR/LNAA ratio was noted in nearly all of the adolescent patients. Despite the heterogeneity of individual biological results, the impulsive behavior subjects in this study seemed to present abnormalities in neurotransmitter precursors.

Adolescent↗
PubMed1992

Methylated catecholamine metabolites for diagnosis of neuroblastoma.

Assays of urinary catecholamines and their metabolites (HVA, VMA, dopamine) permit biochemical diagnosis of neuroblastoma in approximately 80% of patients. The urinary methylated catecholamine metabolites normetanephrine (NMN), metanephrine (MN), and 3-methoxytyramine (3-MT) were analyzed in 18 patients with neuroblastoma and compared with reference values established for 69 healthy pediatric controls. All 18 neuroblastoma patients had raised urinary excretion of at least one of the three commonly assayed metabolites (HVA, VMA, dopamine). Similarly, raised urinary excretion of a methylated metabolite was noted in all but one of the neuroblastoma patients. The 3-MT level was pathologic in 16 of the 18 patients (89%). In this series, 3-MT assay sensitivity was sufficient to warrant trials on a larger population including comparison with patients considered nonsecretors by routine assay procedures.

Adolescent↗
PubMed1992

Circadian variation in total plasma tryptophan. Antidepressant treatment: drugs and phase advance.

The authors investigated hourly total plasma tryptophan concentrations over a 24 hour period in 3 patients with bipolar depression during 2 types of treatment: a phase advance process and conventional antidepressant therapy. Both treatment modalities increased the 24 hour mean tryptophan levels and the amplitude of circadian tryptophan concentrations. By contrast, in a previous study, moderately decreased tryptophan levels and a blunted amplitude in the circadian rhythm were observed in these same patients in a depressive phase.

Adult↗
PubMed1992

Circadian rhythm in plasma noradrenaline of healthy sleep-deprived subjects.

Under normal sleep-wake conditions, noradrenaline (NA) secretions in supine subjects exhibit a weak circadian variation with a peak that occurs around noon; the sleep span is characterized by reduced NA secretion. Some investigators have reported that the circadian NA rhythm is completely obliterated during sleep deprivation. In our laboratory, plasma NA was assayed every hour for 24 h in nine healthy men 20-23 years of age. All men were deprived of sleep and were required to eat and walk around every hour to prevent sleep. However, subjects remained supine for 20 min before blood samples were collected to eliminate the effect of activity. Persistence of a slight decrease in the night concentration in several subjects, despite sleep deprivation, suggests that NA secretion may be influenced by a biological clock whose activity becomes visible when the influence of posture is removed.

Adult↗