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Biomedical subjects

A Valevski

Publications and source records attributed to A Valevski.

29 records · Page 2Linked to original sources
PubMed1992

Blood levels of melatonin, serotonin, cortisol, and prolactin in relation to the circadian rhythm of platelet serotonin uptake.

Blood levels of melatonin, serotonin, cortisol, prolactin, and serotonin uptake by platelets were measured at 08:00, 14:00, 20:00, 02:00, and 08:00 hours in 10 healthy men who ranged in age from 27 to 35 years. The Km values of serotonin active transport by platelets were significantly correlated with melatonin blood levels. There were no other significant correlations. The secretion of steroid hormones and prolactin showed an increase at 02:00 hours; levels of prolactin decreased at 08:00 hours, but steroid levels continued to rise. This finding suggests either a direct effect of melatonin on serotonin active transport or the influence of the suprachiasmatic nucleus on serotonin uptake by platelets. It is also possible that there is a simultaneous decrease in serotonin uptake and decline from peak levels of melatonin due to the rise in steroid secretion.

Adult↗
PubMed1992

Neuroendocrine response to trihexyphenidyl in depressed patients.

The effect of a single dose (10 mg P.O.) of trihexyphenidyl (THP) on plasma cortisol, growth hormone (GH), and immunoreactive beta-endorphin (ir-beta-EP) was studied in seven major depressed patients and seven controls. GH secretion was suppressed (34-41%) by THP in both groups. THP did not affect cortisol secretion in depressed patients and controls. An increase (18%; p less than 0.05) in plasma ir-beta-EP levels was detected in the healthy subjects only. The results of this study do not support the hypothesized altered responsiveness to anticholinergic provocation in major depression. The inhibitory activity of THP on GH secretion indicates the involvement of the cholinergic system in the regulation of GH release in humans.

Adult↗
PubMedDate not supplied

Relaxation times and concentrations of 7Li in the brain of patients receiving lithium therapy.

The present study describes a protocol for the determination of in vivo absolute molar concentrations of Li+ in the human brain using a double tuned 1H/7Li surface coil. The protocol follows the method of Thulborn and Ackerman [J. Mag. Reson. 55, 357-371 (1983)] where the ratio of the signal intensities of 7Li and 1H in the brain is compared to the same ratio in a phantom containing known concentrations of Li+. The 7Li T1 values in the brains of five patients receiving lithium therapy were measured. The average result was T1 = 3.5 +/- 0.25 s. The phantom solution was adjusted to have this T1 value. The protocol was applied for eight bipolar patients receiving lithium therapy. The average ratio of brain to serum lithium molar concentration was found to be 0.59 +/- 0.12.

Adult↗
PubMedDate not supplied

Neural network detection of files of suicidal patients and suicidal profiles.

The optimal configuration of backpropagation (BP) neural networks was determined after 35 trials with different BP configurations evaluating the total detection rate. Ten different training and testing sets were used to identify optimal samples. All trials included sample files of patients with medically serious suicidal attempts (MSSA) and those of non-suicidal patients. Fifty files were used in each group for training and 49 files for testing with no overlap between the samples. The target variable for training was seriousness of suicide attempt (0 = non-suicidal, 1 = MSSA). The input set included 44 demographic, clinical and patient-history variables. The optimal results showed that 93.8% of MSSA and 89.8% of the non-suicidal patient files were detected. Total success rate (TSR) was 91.8% and positive and negative prediction values (PPV, NPV) were 92% and 95.6%, respectively. Living alone (6.76), treatment compliance (5.86), drug abuse or dependence (2.8), global assessment of functioning (GAF) score (1.49), non-paranoid delusions (1.22) and suicide of first degree relative (1.1) were highly associated with MSSA according to the Garson calculation. However, logistic regression attributed high importance to hallucinations (p < 0.0001), diagnosis (p < 0.002), number of children (p < 0.006), GAF score (p < 0.006), employment status (p < 0.02) and stressors (p < 0.03). It was shown that: backpropagation neural networks are very successful in identifying records of MSSA patients; a high GAF score is associated with high risk of MSSA and is the only common variable identified by both methods; and backpropagation identified two non-specific factors (living alone and treatment compliance) whereas statistics found specific factors (hallucinations and diagnosis) highly associated with MSSA.

Adolescent↗
PubMedDate not supplied

Response of catatonia to risperidone: two case reports.

The present study describes two patients, both of Yemenite origin, with catatonic schizophrenia who responded to treatment with risperidone. One had a long history of psychiatric disorder, whereas the other was a first-episode, drug-naive patient. Our observation agrees with previous reports on the use of risperidone and other novel neuroleptic agents in the treatment of catatonia of different etiologies.

Adult↗
PubMedDate not supplied

Effect of amantadine on sexual dysfunction in neuroleptic-treated male schizophrenic patients.

Twelve male schizophrenic outpatients treated with neuroleptics took part in an open-label drug study to assess the impact of co-administration of amantadine hydrochloride (100 mg daily for 6 weeks) on sexual function. Amantadine improved the patients' scores in three out of four areas of sexual function: desire (p < 0.02), erection (p < 0.05), and satisfaction from sexual performance (p < 0.05); there was no change in ejaculatory function. Amantadine may be effective for improving sexual function in male schizophrenic patients receiving neuroleptic medication.

Adult↗