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Biomedical subjects

S Pavel

Publications and source records attributed to S Pavel.

At least 91 records · Page 5Linked to original sources
PubMed1983

Eumelanin (precursor) metabolites as markers for pigmented malignant melanoma: a preliminary report.

The pigmented form of malignant melanoma is a tumor with an exceptionally high production of melanin. It is therefore comprehensible that the precursors of melanin and/or their metabolites are excreted in elevated amounts during the course of this disease. Using gas chromatography--mass spectrometry we were able to identify five indolic compounds in the urine of melanoma patients: 5,6-dihydroxyindole (5,6DHI), 5-hydroxy-6-methoxyindole (5H6MI), 6-hydroxy-5-methoxyindole (6H5MI), and 5-hydroxy-6-methoxyindolyl-2-carboxylic (5H6MI2C) and 6-hydroxy-5-methoxyindolyl-2-carboxylic acids (6H5MI2C). For their quantitative mass fragmentographic analyses, deuterium-labeled analogs have been synthesized. The first experience with these measurements is presented.

Gas Chromatography-Mass Spectrometry↗
PubMed1982

Effects of arginine vasotocin on REM sleep in narcoleptics and in symptomatic hypersomniacs.

Arginine vasotocin (AVT), in doses of 1.5 microgram, administered intranasally to two narcoleptics (a male aged 42 years and a female aged 35 years), as well as to 5 symptomatic hypersomniacs (3 females and 2 males), aged 25-57 years, induced very rapidly in most instances in sleep with REM periods at onset and markedly increased in amount of REM sleep during a fixed period of 180 min of sleep recording. After AVT administration there was a significant shortening of the time of occurrence of the first REM sleep period both in narcoleptics (t test = 0.05 greater than P greater than 0.025) and in symptomatic hypersomniacs (t test = 0.02 greater than P greater than 0.01).

Adult↗
PubMed1981

Identification of two Thormählen-positive compounds from melanotic urine by gas chromatography-mass spectrometry.

The isolation of two Thormählen-positive compounds from the urine of a patient with malignant melanoma and the elucidation of their structure by gas chromatography-mass spectometry is described. The compounds were isolated using a poly-N-vinylpyrrolidone column and separated by preparative thin-layer chromatography. After elution they were analyzed by gas chromatography and gas chromatography-mass spectrometry as their trimethylsilyl derivatives and after hydrolysis also as their tert.-butyldimethylsilyl derivatives. The results showed the main Thormählen-positive compound A to be the glucuronide of 5-hydroxy-6-methoxyindole, whereas the minor compound AX appeared to be the glucuronide of its isomer 6-hydroxy-5-methoxyindole.

Chromatography, Thin Layer↗
PubMed1981

Narcoleptic-like alterations of the sleep cycle in cats induced by a specific vasotocin antiserum.

A specific arginine vasotocin (AVT) antiserum (10 microliter) injected undiluted into the lateral ventricle of unanesthetized cats, induced sleep onset REM periods, markedly increased the number of REM periods, and dramatically decreased REM sleep latency. The amount of total REM sleep significantly increased and the amount of total NREM sleep significantly decreased. Neither a specific arginine vasopressin or oxytocin antiserum nor a normal rabbit serum injected undiluted into the lateral ventricle in the same volume (10 microliter) was able to reproduce the effects of the AVT antiserum. It is concluded that pineal AVT is physiologically involved in the induction and/or circadian organization of REM sleep.

Animals↗
PubMed1981

REM sleep suppression in cats by melatonin.

The pineal indole melatonin, injected into the third ventricle of unanesthetized cats, induced NREM sleep within 11-15 min and suppressed REM sleep for about 3 hr. A dose-related effect could be established between 1, 10 and 100 ng melatonin. The reappearance of REM sleep at about 3 hr following melatonin administration occurred with a marked rebound. The present results further support the hypothesis that melatonin represents the releasing hormone for pineal arginine vasotocin.

Animals↗
PubMed1981

REM sleep induction in prepubertal boys by vasotocin: evidence for the involvement of serotonin containing neurons.

The pineal nonapeptide hormone arginine vasotocin (AVT) (100 ng/kg) administered intra-nasally (IN) to healthy prepubertal boys, dramatically increased the amount of REM sleep, decreased REM sleep latency, and induced REM periods at sleep onset. Neither arginine vasopressin (AVP) nor oxytocin administered IN at the dose of 100 ng/kg was able to reproduce the effects of AVT, demonstrating its high specificity. Methergoline, a selective central 5-hydroxytryptamine (5-HT) receptor blocker, administered IN at the dose of 100 ng/kg, completely prevented AVT induction of REM sleep. Fluoxetine, a specific 5-HT uptake inhibitor, administered IN at the dose of 25 microgram/kg, 10 min after AVT, greatly potentiated the effects of AVT in inducing REM periods at sleep onset and in increasing the amount of REM sleep and the percentage of dream reports. It is suggested that AVT induces REM sleep in prepubertal boys by interfering with 5-HT neurotransmission and that the high sensitivity of prepubertal boys to AVT reflects an immaturity of REM triggering centers.

Adolescent↗
PubMed1981

A qualitative gas chromatographic analysis of substituted 5,6-dihydroxyindoles from the urine of patients with melanoma.

A qualitative gas chromatographic analysis of trimethylsilylated ethyl acetate extracts of melanotic urine revealed 5 indolic compounds, which have been identified as substituted 5,6-dihydroxyindoles. Ethyl acetate extracts of melanotic urines at pH 2.0 contained isomeric 5-hydroxy-6-methoxy and 6-hydroxy-5-methoxy-indolyl-2-carboxylic acids which were not separable under the conditions used. A careful hydrolysis of melanotic urine with a Helix pomatia preparation followed by extraction at pH 6.5 in a nitrogen atmosphere released 3 additional indolic compounds from their conjugated form. Using gas chromatographic-mass spectrometric analysis they were identified as 5-hydroxy-6-methoxy, 6-hydroxy-5-methoxyindole and 5,6-dihydroxyindole.

Chromatography, Gas↗
PubMed1981

Dopa oxidase activity and ceruloplasmin in the sera of hamsters with melanoma.

Two simple spectrophotometric assays have been employed for the measurement of dopa oxidase activity and ceruloplasmin polyphenol oxidase activity in the sera from normal hamsters and hamsters bearing melanotic melanoma. Both activities were found to be augmented in tumor animals, the dopa oxidase activity much more prominently. The levels of the enzymes tested increased proportionally to the tumor mass.

Animals↗
PubMed1981

The identification of Thormählen positive melanogen "A" from the urine of melanoma patients as 6-methoxy-5-indolylglucosiduronate.

The Thormählen positive melanogen previously determined as "A" has been isolated from melanotic urine by means of column chromatography on Amberlite IR 45, DEAE cellulose and Dowex 50. According to its behavior during a study with 1H--NMR spectra it has been found that the isolatd compound is 6-methoxy-5-indolyglucosiduronate, the metabolite of 5,6-dihydroxyindole. The possible formation and biotransformation of this compound is discussed.

Chromatography, DEAE-Cellulose↗
PubMed1980

Vasotocin, melatonin and narcolepsy: possible involvement of the pineal gland in its patho-physiological mechanism.

Both the pineal nonapeptide hormone arginine vasotocin (AVT) (2.5 micrograms) administered intra-nasally and the pineal indole melatonin (50 mg) administered intravenously to three male narcoleptics (two with auxiliary symptoms and one with sleep attacks only), dramatically increased the amount of REM sleep and decreased REM sleep latency. The duration of the sleep onset REM periods in the two narcoleptics with auxiliary symptoms increased by more than 100 percent after AVT and melatonin administration. In the narcoleptic with sleep attacks only both AVT and melatonin induced REM periods at sleep onset. The hypothesis is advanced that narcolepsy represents an impairment of the melatonin-AVT control in the induction and circadian organization of REM sleep associated with an immaturity of REM triggering centers.

Adolescent↗
PubMed1980

Presence of relatively high concentrations of arginine vasotocin in the cerebrospinal fluid of newborns and infants.

Lumbar cerebrospinal fluid (CSF) was obtained from healthy newborns, infants, and children of both sexes between 23-777 days of age. Bioassay of the CSF revealed relatively high antidiuretic and hydroosmotic activities. Rat uterine activities could be detected only in the CSF of newborns, and these activities were increased in the presence of magnesium. The antidiuretic and hydroosmotic activities of CSF from newborns were significantly higher than the same CSF activities of infants (P less than 0.01) and children (P less than 0.001). No sex differences were observed in the above biological activities of CSF. The ratio of these activities, their susceptibility to tryptic digestion, and the increase of the rat uterine activity by magnesium demonstrate the presence in CSF of a basic peptide indistinguishable from synthetic arginine vasotocin. In contrast to the CSF of healthy newborns and infants, neither antidiuretic nor hydroosmotic activities could be detected in the CSF of a boy, aged 413 days, with a pineal tumor and precocious puberty.

Age Factors↗
PubMed1980

Reversal by arginine-vasotocin of the effects of pinealectomy on the amount of 5-hydroxytryptamine in the hypothalamus and the concentrations of luteinizing hormone and follicle-stimulating hormone in the plasma of immature male rats.

Pinealectomy in immature (25-day-old) male Wistar rats significantly decreased the content of 5-hydroxytryptamine (5-HT) in the hypothalamus and increased concentrations of plasma LH and FSH 3 days after surgery. Extremely small amounts (10(-4) pg) of arginine-vasotocin (AVT) injected into the third ventricle (pineal recess) 5 min after pinealectomy completely prevented the decrease in the hypothalamic content of 5-HT and the increase in the concentration of LH and FSH in the plasma. It is suggested that AVT prevented the increase of plasma levels of LH and FSH after pinealectomy by increasing levels of 5-HT at postsynaptic receptor sites.

Animals↗