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Biomedical subjects

A Wolkin

Publications and source records attributed to A Wolkin.

36 records · Page 2Linked to original sources
PubMed1989

Dopamine blockade and clinical response: evidence for two biological subgroups of schizophrenia.

Because CNS neuroleptic concentration cannot be directly measured in patients, the relation between clinical response and extent of dopamine receptor blockade is unknown. This relationship is critical in ascertaining whether nonresponse to neuroleptics is the result merely of inadequate CNS drug levels or of more basic biological differences in pathophysiology. Using [18F]N-methylspiroperidol and positron emission tomography, the authors assessed dopamine receptor occupancy in 10 schizophrenic patients before and after treatment with haloperidol. Responders and nonresponders had virtually identical indices of [18F]N-methylspiroperidol uptake after treatment, indicating that failure to respond clinically was not a function of neuroleptic uptake or binding in the CNS.

Adolescent↗
PubMed1988

Serial [18F]N-methylspiroperidol PET studies to measure changes in antipsychotic drug D-2 receptor occupancy in schizophrenic patients.

An indirect approach to the relationship among drug dose, plasma level, and the competition between a labeled neuroleptic drug [18F]N-methylspiroperidol (18F-NMS) for binding sites in striatal tissue in normal and schizophrenic subjects is described. The slope of the line plotting the ratio of activity in the striatum (As) to activity in the cerebellum (Ac) versus time up to 5 hr postinjection of 18F-NMS is taken as a marker of site occupancy. An inverse relation between labeled competitor uptake and drug plasma level has been demonstrated for the classes of antipsychotic drug studied. Striatal uptake studies showed a progressive increase in all subjects following drug withdrawal up to 156 hr postwithdrawal. Uptake and clearance of 18F-NMS in cerebellar tissue was not appreciably affected by antipsychotic medication or drug withdrawal.

Adult↗
PubMed1988

Low frontal glucose utilization in chronic schizophrenia: a replication study.

Frontal/posterior ratios of cerebral glucose metabolism as determined by positron emission tomography were significantly lower in 13 chronic schizophrenic patients than in eight normal control subjects, as were absolute metabolic rates in both the frontal and posterior regions. The differences were not accounted for by cerebral atrophy.

Adult↗
PubMed1987

Effects of amphetamine on local cerebral metabolism in normal and schizophrenic subjects as determined by positron emission tomography.

The effects of d-amphetamine (0.5 mg/kg PO) on regional cerebral glucose utilization were measured with Positron Emission Tomography (PET). Subjects included ten chronic schizophrenics and six controls who received amphetamine, and six chronic schizophrenics and nine controls who received placebo or no treatment. Amphetamine decreased glucose metabolism in all regions studied (frontal, temporal, and striatal) in normal and schizophrenic subjects. The metabolic effects of amphetamine were correlated with plasma level of the drug. Cortical atrophy was associated with a blunted metabolic response.

Adult↗
PubMed1987

Essential fatty acid supplementation during early alcohol abstinence.

Interactions between ethanol, prostaglandins, and essential fatty acids (EFA) have led to the hypothesis that acute alcohol withdrawal and the sequelae of chronic alcoholism may be related to an EFA/prostaglandin deficiency. To test this hypothesis, EFA profiles in blood-lipid fractions, serum liver enzymes, cognitive function, and alcohol craving were measured in 27 acutely abstinent alcoholics before and after a 3-week double-blind trial of EFA supplementation. Upon entry into the study, alcoholics had significant differences in EFA levels as compared to normal controls, and serum levels of liver enzymes tended to correlate with these EFA levels. After 21 days, cognitive function, alcohol craving, and liver enzymes all improved in both the EFA and placebo groups; most EFA levels also approached normal values. There were no treatment effects of EFA supplementation at the dose used.

Adult↗
PubMed1986

Essential fatty acid supplementation in tardive dyskinesia.

Preclinical and clinical observations suggest that enhancement of prostaglandin activity inhibits catecholamine release and may have antidyskinetic effects. A double-blind therapeutic trial with prostaglandin precursor essential fatty acids was conducted in 16 patients with tardive dyskinesia. No beneficial effects were seen.

Clinical Trials as Topic↗
PubMed1986

The dexamethasone suppression test and response to placebo.

The predictive value of the dexamethasone suppression test (DST) was evaluated in two consecutive double-blind, placebo-controlled trials evaluating 61 depressed inpatients randomized to either one of two drugs, sertraline or oxaprotiline, or placebo over a 4-week clinical trial. For 30 patients who completed at least 3 weeks of double-blind treatment on either drug, the initial DST was not predictive of response to drug treatment. For the 17 patients who completed at least 3 weeks of double-blind treatment on placebo, the presence of a positive DST predicted a statistically significantly poorer response to placebo as opposed to a negative DST. These preliminary findings suggest that for depressed individuals who present with a positive DST, remission without active medication is less likely and somatic treatment should be considered.

1-Naphthylamine↗
PubMed1985

Amphetamine response and relapse risk after depot neuroleptic discontinuation.

Twenty-five schizophrenic outpatient subjects in a depot neuroleptic discontinuation study received an amphetamine challenge approximately 6 weeks after their last dose. Only five of these showed greater than three-point increases in positive symptoms on the BPRS, and all five relapsed within 30 days of the challenge. The 20 with less than three-point increases in positive symptoms showed extremely variable stability, relapsing from 20- greater than 600 days after the challenge. Thus, increase in positive symptoms after amphetamine may identify a group at risk for rapid relapse after neuroleptic discontinuation, but lack of such a response gives little prognostic information.

Adult↗
PubMed1985

Persistence of cerebral metabolic abnormalities in chronic schizophrenia as determined by positron emission tomography.

Local cerebral metabolic rates were determined by positron emission tomography and the deoxyglucose method in a group of 10 chronic schizophrenic subjects before and after somatic treatment and in eight normal subjects. Before treatment, schizophrenic subjects had markedly lower absolute metabolic activity than did normal controls in both frontal and temporal regions and a trend toward relative hyperactivity in the basal ganglia area. After treatment, their metabolic rates approached those seen in normal subjects in nearly all regions except frontal. Persistence of diminished frontal metabolism was manifested as significant relative hypofrontality. These findings suggest specific loci of aberrant cerebral functioning in chronic schizophrenia and the utility of positron emission tomography in characterizing these abnormalities.

Adult↗
PubMed1984

TRH test abnormalities in psychiatric disorders.

Blunted responses to thyrotropin-releasing hormone (TRH) stimulation have been found consistently in depressed patients, and have been reported in other affective disorders as well. In a smaller number of schizophrenic subjects, TRH tests have generally been normal. Thus, it has been suggested that this test may have diagnostic utility in distinguishing schizophrenia from affective disorders. In the present study the TRH test was performed upon a sample of 51 subjects that included 17 schizophrenics in order to further study the diagnostic or symptom specificity of this endocrine test. Abnormal TRH tests were present in both schizophrenic and affectively disturbed patients. There were no correlations with ratings of depression or other aspects of psychopathology. Factors which may have previously obscured abnormal TRH tests in schizophrenia are discussed.

Bipolar Disorder↗
PubMed1982

Red cell phospholipids in schizophrenia.

Phospholipids in red blood cells (RBCs) of schizophrenics and controls were determined. Three different RBC preparations and two different extraction methods were used. Phospholipids were separated by thin layer chromatography and by high pressure liquid chromatography, and were quantified by phosphorus analysis and by ultraviolet absorption. Findings were consistent with values previously reported for normals. However, in contrast to recent reports of elevated phosphatidylserine levels in schizophrenics' RBCs, we observed no differences between populations.

Adult↗
PubMed1977

Cannabidiol--antiepileptic drug comparisons and interactions in experimentally induced seizures in rats.

A comparison of the anticonvulsant and neurotoxic effects of cannabidiol (CBD), delta 9tetrahydrocannabinol, cannabinol and antiepileptic drugs (phenytoin, phenobarbital, carbamazepine, chlordiazepoxide, clonazepam, ethosuximide and trimethadione) was made in rats. Median effective potencies (ED 50 values) for maximal electroshock, audiogenic seizures and TD50 values for a rotor rod neurotoxicity test were calculated. Additionally, the interactive effects of CBD and the antiepileptic drugs against maximal electroshock and audiogenic seizures were studied. Each drug was given orally at peak effect time. CBD was an effective and relatively potent anticonvulsant in both maximal electroshock and audiogenic seizure tests. The anticonvulsant potency of phenytoin was significantly increased when combined with phenobarbital, CBD and phenobarbital plus CBD. Additionally, CBD reliably reduced the anticonvulsant potencies of chlordiazepoxide, clonazepam, trimethadione and ethosuximide. These data indicate that CBD is an effective anticonvulsant with a specificity more comparable to drugs clinically effective in major than minor seizures. Furthermore, it appears that CBD enhances the anticonvulsant effects of the former and reduces the effects of the latter types of antiepileptic drugs.

Acoustic Stimulation↗
PubMedDate not supplied

Cardiovascular effects of 0.5 milligrams per kilogram oral d-amphetamine and possible attenuation by haloperidol.

In a series of earlier studies, an oral dose of 0.5 mg/kg d-amphetamine was administered to 81 patients with schizophrenia and eight normal control subjects. Seven more subjects with schizophrenia received placebo. Blood pressure and pulse rate were monitored before and 3 hours after drug administration. Blood pressure increased in both amphetamine groups, whereas placebo had no effect. However, pulse rate did not change in the schizophrenic group and only increased after 3 hours in normal control subjects as blood pressure began to decrease. Significant negative correlations between systolic blood pressure and pulse rate occurred at 2 and 3 hours, suggesting that the early cardiovascular response to amphetamine is an increase in blood pressure that recruits reflex control of heart rate. Eighteen of these subjects had hypertensive responses. Six subjects received 5 mg haloperidol intramuscularly, and 12 others had their blood pressure monitored until normalization. Haloperidol led to a more rapid decline of some but not all indices of blood pressure, suggesting that amphetamine-induced hypertension may have a dopaminergic component.

Adult↗