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Biomedical subjects

B Spivak

Publications and source records attributed to B Spivak.

At least 19 recordsLinked to original sources
PubMed2006

Long-range correlations in the speckle patterns of directed waves.

We develop a general method for calculating statistical properties of the speckle pattern of coherent waves propagating in disordered media. In some aspects this method is similar to the Boltzmann-Langevin approach for the calculation of classical fluctuations. We apply the method to the case where the incident wave experiences many small angle scattering events during propagation, but the total angle change remains small. In many aspects our results for this case are different from results previously known in the literature. The correlation function of the wave intensity at two points separated by a distance r, has a long-range character. It decays as a power of r and changes sign. We also consider sensitivities of the speckles to changes of external parameters, such as the wave frequency and the incidence angle.

Journal Article↗
PubMed2004

Signature of the electron-electron interaction in the magnetic-field dependence of nonlinear I-V characteristics in mesoscopic systems.

We show that the nonlinear I-V characteristics of mesoscopic samples with metallic conductivity should contain parts which are linear in the magnetic-field and quadratic in the electric field. These contributions to the current are entirely due to the electron-electron interaction and consequently they are proportional to the electron-electron interaction constant. We also note that both the amplitude and the sign of the nonlinear part of the current exhibit random oscillations as a function of temperature.

Journal Article↗
PubMed2004

Clozapine in the treatment of obsessive-compulsive symptoms in schizophrenia patients: a case series study.

INTRODUCTION: Obsessive-compulsive (OC) symptoms have been observed in a substantial proportion of schizophrenic patients. There are some reports describing the appearance de novo or reemergence of preexisting OC symptoms under clozapine (CLZ) therapy. However, there are also reports describing a positive effect of CLZ therapy in OC schizophrenic patients. It seems that comorbid OC symptoms are common among CLZ-treated refractory schizophrenic patients and are likely to be an integral part of their illness. The complex nature of the treatment response in this group of schizophrenic patients is as yet unclear. The effects of CLZ on OC symptoms may vary, with evidence of improvement in some and worsening among others. METHODS: The present case series study describes our experience with CLZ as a sole agent (n = 10) or in combination with serotonin reuptake inhibitors (n = 5), in schizophrenic patients with prominent OC symptomatology. RESULTS: Systematic analysis of clinical features of our patients, as well as findings in the literature to date, led us to suggest some factors that may predict response to CLZ treatment in treatment-resistant schizophrenic patients with prominent OC symptoms: 1) schizophrenic patients who began to exhibit OC symptoms within the course of the psychotic process need and might to be successfully treated with CLZ alone; 2) when OC symptomatology preceded the development of schizophrenic process, CLZ monotherapy is inefficient and may even worsen OC symptoms; therefore, it should be treated concomitantly with specific anti-obsessive agents; 3) in both groups there is a definite dose-related pro-obsessive influence of CLZ when it is given in high doses. DISCUSSION: Further controlled investigations in a larger cohort of OC schizophrenic patients are needed to substantiate our hypothesis. OCD:Obsessive-compulsive disorder OCS:Obsessive-compulsive symptoms SRI:Serotonin reuptake inhibitors

Adult↗
PubMed2001

Analysis of neurosteroid levels in attention deficit hyperactivity disorder.

Neurosteroids are important neuroactive substrates with demonstrated involvement in several neurophysiological and disease processes. Attention deficit hyperactivity disorder (ADHD) has been associated with dysregulation of the catecholaminergic and serotonergic systems, however its relationship to irregularities or changes in neurosteroid levels remains unknown. We examined the relationship between blood levels of dehydroepiandrosterone (DHEA), its principal precursor pregnenolone and its principal metabolite dehydroepiandrosterone sulphate (DHEAS) in 29 young male subjects aged 7-15 years with DSM-IV criteria of ADHD. Subjects were evaluated by a specially designed scale, following which patients were divided into two groups according to severity of symptomatology. Results indicated significant inverse correlations between clinical symptomatology and levels of DHEA and pregnenolone in the total group. These inverse correlations were particularly evident in the less severe group of subjects. Levels of DHEA and DHEAS were inversely correlated with the hyperactivity subscale. Furthermore, using median blood levels as a cut-off indicator, higher blood levels of DHEA and DHEAS were associated with fewer ADHD symptoms, in particular hyperactivity symptomatology. Our findings suggest a possible protective effect of various neurosteroids on the expression of ADHD symptomatology.

Adolescent↗
PubMed2001

Zuclopenthixol treatment of behavioral disturbances in mentally retarded children and adolescents: an open-label study.

The present open-label study assessed the efficacy of zuclopenthixol, an thioxanthene neuroleptic with combined dopamine receptors (D1/D2) antagonist activity, in the treatment of severe behavioral disturbances in mentally retarded children and adolescents. A sample of 15 (11 males, 4 females) mentally retarded children and adolescents, ages 5-18 years (12.2 +/- 2.3 [mean +/- SD] years), all exhibiting severe behavioral disturbances, was evaluated. The 12-week zuclopenthixol treatment (up to 26 mg/day) was initiated after a week's washout from previous antipsychotic agents. An assessment of the behavioral disturbances was performed using the 14-item Checklist for Behavior Problems Involving Limited or No Social Awareness (CBP-NSA). The Udvalg for kliniske undersøgelser (UKU) Side Effect Rating Scale was used to assess the pharmacologic side effects. Results show a significant reduction in total CBP-NSA scores and in individual items such as hyperactivity, aggressive behavior, and temper tantrums (p < 0.001 for each). It seems that zuclopenthixol monotherapy is effective and well tolerated in the treatment of severe behavioral disturbances in mentally retarded children and adolescents. Double-blind, placebo-controlled studies are needed before definitive conclusions can be drawn regarding the efficacy and safety of zuclopenthixol for this population.

Adolescent↗
PubMed2000

Mesoscopic sensitivity of speckles in disordered nonlinear media to changes of the scattering potential

We show that the sensitivity of wave speckle patterns in disordered nonlinear media to changes of scattering potential increases with sample size. For large sizes the sensitivity diverges, which implies that for a given coherent wave incident on a sample there are multiple solutions for the spatial distribution of the wave density. The number of solutions increases exponentially with the sample size.

Journal Article↗
PubMed2000

Frequency of neuroleptic malignant syndrome in a large psychiatric hospital in Moscow.

A ten-year prospective survey of neuroleptic malignant syndrome (NMS) was performed in a major psychiatric hospital (1,510 beds) in Moscow. All inpatients who developed a persistent and severe extrapyramidal rigidity accompanied by fever after exposure to neuroleptic medication were screened for NMS. The diagnosis of NMS was established according to Levenson's criteria and at a later stage all NMS cases were reevaluated using the DSM-IV research criteria. Data on age, gender and psychiatric diagnoses were analyzed. Of the 78,708 inpatients treated with neuroleptic agents, 19 separate patients had an episode of NMS, for a frequency of 0.02%. Mortality rate was 10.5% (2/19 patients). Of the three potential risk factors studied, only young age (</= 25 years) was significantly associated with an increased frequency of NMS (P < 0. 01). The low rate of NMS found here compared to studies in other countries may be due to the stringent demands for NMS diagnosis. More large-scale prospective studies including detailed clinical and laboratory data are needed to clarify these differences and their impact on the prevalence and risk factors of NMS.

Adult↗
PubMed2000

Hemispheric function in disorganized type schizophrenia: performance on the quality extinction test.

We assessed hemisphere function in right-handed male chronic, disorganized type schizophrenic patients (N = 60, age range 18-45 years) using the Quality Extinction Test (QET), in comparison to 20 right-handed male healthy controls in the same age range. The QET analysis discriminated between the disorganized schizophrenic patients and the controls. QET results indicated that chronic schizophrenic patients were less sensitive to tactile stimuli in both hands as compared to controls. Furthermore, the sensitivity to tactile stimuli of the left hand was less than that of the right hand in the schizophrenic patients. In contrast, in the normal controls the sensitivity was similar in both hands. These results indicate possible right hemisphere dysfunction together with disturbance in interhemispheric transmission through the corpus callosum in chronic, disorganized type schizophrenic patients.

Adolescent↗
PubMed2000

Elevated circulatory level of GABA(A)--antagonistic neurosteroids in patients with combat-related post-traumatic stress disorder.

BACKGROUND: Post-traumatic stress disorder (PTSD) is a multisystem neurobiological disorder with chronic alterations in various neurochemical systems. Levels of the GABA(A)--antagonistic neurosteroids plasma dehydroepiandrosterone (DHEA) and its sulphate derivate, dehydroepiandrosterone sulphate (DHEAS) may be relevant to depressive and anxiety disorders, including PTSD. METHODS: We assessed the circulatory levels of morning plasma DHEA and DHEAS in 21 male outpatients with untreated chronic combat-related PTSD (CR-PTSD), and 18 healthy control male subjects. RESULTS: Compared with the control subjects, the PTSD patients showed significantly higher plasma DHEA and DHEAS levels. CONCLUSIONS: Chronic CR-PTSD may be associated with increased circulatory level of neuroactive steroids with inhibitory activity at the GABA(A) receptors. Neurosteroid-induced decreased GABAergic tone may be relevant to the symptomatology and pathophysiology of chronic PTSD, as well as to the frequent co-morbidity of PTSD with depression and anxiety disorders.

Adult↗
PubMed2000

Prospective evaluation of circulatory levels of catecholamines and serotonin in neuroleptic malignant syndrome.

OBJECTIVE: Neuroleptic malignant syndrome (NMS) may be associated with a dysregulation of the catecholaminergic and serotonergic systems. The objective of the present study was to evaluate prospectively the circulatory levels of serotonin (5-HT), epinephrine (E) and dopa in patients suffering from NMS. METHOD: Platelet-poor plasma (PPP) levels of serotonin, epinephrine and dopa in eight NMS patients were measured twice: in the acute state and in the state of remission. RESULTS: PPP dopa concentration was significantly lower in acute NMS state compared to the remission state (P = 0.023). In contrast, PPP E level was significantly higher (P = 0.019) in the acute NMS state and PPP 5-HT concentrations in the acute state tended to be higher than those at remission (P = 0.078). 5-HT/dopa ratio was significantly higher in the acute NMS (P = 0.015). CONCLUSION: These results may reflect reduction in dopaminergic function and increase in adrenergic and serotonergic activity in the acute NMS state.

Acute Disease↗
PubMed2000

Medical confidentiality in the new Israeli Patients' Rights Act (1996): does it add or detract?

Medical confidentiality is dealt with in various laws in Israel. The 1996 Israel Patient's Rights Act approaches the subject of confidentiality in an extensive and fairly detailed manner which includes several innovations in relation to previous laws. This article will review the old and the new legislations on confidentiality, and will analyze and discuss the implications and potential problems for psychiatric clinical practice. The new Act will also be examined in light of the World Health Organization guidelines on Mental Health Care Laws.

Confidentiality↗
PubMed2000

The patient's right to know, in the 1996 Israel law for the rights of the patient: the pains of progress.

The 1996 Israel Law for Patients' Rights, Sections 21 and 22, introduces to the field of health legislation two new entities: internal examination committees and quality-control committees. The former are to be established when there is a need to investigate unusual, irregular or exceptional events related to diagnosis and/or treatment. Furthermore, the 1996 Law directs the internal examination committee to reveal its findings to the patient or to his representatives. This approach has evoked strong controversy up until the present time. On the other hand, the quality-control committees which produce privileged information have been smoothly integrated into psychiatric practice. This paper presents the history of the creation of these two committees based on law, and examines their effect on the daily practice of medicine and the reaction of the physicians' guild to their activation. It also discusses the effect of the implementation of these committees on the level of mutual trust between therapist and patient, and on medical morality and its relationship to the social phenomenon known as defensive medicine. Feasible solutions for controversial issues are presented. These include participation of patients or their representatives in the internal examination committees, privileged peer reviews, increased utilization of quality control committees and of ethics committees.

Humans↗
PubMed1999

Low platelet-poor plasma concentrations of serotonin in patients with combat-related posttraumatic stress disorder.

BACKGROUND: Combat-related posttraumatic stress disorder (CR-PTSD) is associated with a dysregulation of various neurotransmitter systems. METHODS: We assessed levels of platelet-poor plasma (PPP) norepinephrine (NE), and serotonin (5-HT), and 24-hour urinary excretion of NE, dopamine (DA), and homovanillic acid (HVA) in 17 male outpatients with untreated chronic CR-PTSD (age, 33.1 +/- 7.4 years) and 10 normal control subjects (age, 35.8 +/- 2.7 years). RESULTS: Compared with the control subjects, the PTSD patients showed significantly lower PPP 5-HT levels, elevated PPP NE levels, and significantly higher mean 24-hour urinary excretion of all three catecholamines (NE, DA, and HVA). The 24-hour urinary HVA values of the CR-PTSD patients correlated significantly and positively with the total Impact of Event Scale scores and the avoidance symptoms cluster scores, and the PPP 5-HT levels correlated negatively with the Hamilton Anxiety Rating Scale scores. The PPP NE/5-HT ratio was significantly higher in the study group than in the control subjects. CONCLUSIONS: We believe this combined enhanced noradrenergic activity and diminished 5-HT activity may be relevant to the neurobiology of CR-PTSD.

Adult↗
PubMed1999

Elevated cellular immune response to human heat-shock protein-60 in schizophrenic patients.

Heat shock protein-60 (HSP60) is implicated in several autoimmune diseases as a triggering antigen. Based on the autoimmune hypothesis of schizophrenia, we examined cellular and humoral responses against HSP60 and a series of its peptide fragments with peripheral blood samples of schizophrenic patients and healthy subjects each of group size between 12 to 32 participants. The average stimulation indices of peripheral blood mononuclear cells (PBMC) to HSP60 were 3.17 +/- 0.36 (mean +/- SE) for schizophrenic patients and 2.23 +/- 0.24 (mean +/- SE) for healthy subjects, with a significant difference between the groups (P = 0.0457). In parallel, 38 synthetic peptide fragments of HSP60, each of 18-21 amino acids, were tested for in vitro sensitization of PBMC. With one peptide (p32) the average stimulation index of PBMC from schizophrenic patients was significantly higher than that obtained for PBMC of control subjects (P = 0.0006). Comparing the cellular immune response to p32 between patients who were distinctive responders (n = 10) or non-responders (n = 10) to neuroleptic treatment indicated a similar elevation of cellular response in these groups. Antibodies against HSP60 were screened by dot-blot and ELISA in the sera of the above blood samples. Titers of IgG and IgM against HSP60 were found to be of similar magnitude in schizophrenic patients and in controls. Titers of IgA against HSP60 were somewhat higher in the sera of schizophrenic patients in comparison to sera of control subjects (P = 0.0605).

Adult↗
PubMed1999

Homicide by schizophrenic patients in Israel.

Thirty-three schizophrenic inpatients aged 45.3 +/- 13.5 years who had been found not guilty of homicide by reason of insanity were compared with 28 schizophrenic patients matched for age, sex and duration of disease who had not committed any crime. Statistical analysis revealed a high rate in the study group of individual factors associated with aggression, such as alcohol abuse, previous contact with the police, aggressive behavior and threats (P < 0.05). Significantly more of them were also immigrants (P < 0.05). There was no between-group difference in familial factors. These findings support earlier studies indicating that schizophrenic patients with the profile of alcoholism, aggressiveness and foreign country of origin are at high risk of homicidal behavior.

Adolescent↗
PubMed1999

The effect of long-term antipsychotic treatment on the body weight of patients suffering from chronic schizophrenia: clozapine versus classical antipsychotic agents.

The aim of this study was to evaluate the effect of long-term clozapine treatment on body weight changes in neuroleptic-resistant chronic schizophrenic patients and to compare it with that of classical antipsychotic agents. The body mass index (BMI) of 96 neuroleptic-resistant chronic schizophrenic patients was calculated before the beginning and after long-term (mean +/- SD 1.7 +/- 1.3 years) clozapine treatment. These data were compared to the BMI of 98 chronic schizophrenic patients maintained on classical antipsychotic agents for a similar duration (mean +/- SD 1.9 +/- 1.6 years). A significant elevation in BMI was detected in both groups during these periods (P < 0.0001 versus baseline, for both groups). The change in BMI (delta BMI) was similar in both groups (P < 0.9). We conclude that the increase in body weight caused by long-term (> 6 months) clozapine treatment is comparable to that obtained following long-term classical antipsychotic agents treatment.

Adult↗
PubMed1999

Circulatory levels of catecholamines, serotonin and lipids in attention deficit hyperactivity disorder.

Attention deficit hyperactivity disorder (ADHD) may be associated with a dysregulation of the catecholaminergic and serotonergic systems. Furthermore, ADHD is frequently complicated by aggressive impulsive behaviour, which is suggested to be related to low serum cholesterol levels. We examined the relationship between blood serotonin, norepinephrine, dopa and lipid levels and the degree of hyperactivity, impulsiveness, lack of concentration, and aggressiveness in boys with ADHD of low and high severity as determined by a specially designed formulated scale based on the DSM-IV criteria for ADHD. No differences were noted between the groups in any of the peripheral biological parameters except blood serotonin, for which a tendency (P=0.08) towards lower levels was observed in the children with more severe disorder. We conclude that children with severe ADHD may have a different serotonin turnover compared to children with mild ADHD. These results may have implications for our understanding of the pathogenesis of ADHD, at least the more severe type.

Adolescent↗