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Biomedical subjects

M Davidson

Publications and source records attributed to M Davidson.

At least 217 records · Page 12Linked to original sources

CSF homovanillic acid in schizotypal personality disorder.

CSF concentrations of homovanillic acid (HVA) were measured in 10 patients with schizotypal personality disorder and 14 patients with other personality disorders. The patients with schizotypal personality disorder had higher CSF HVA concentrations than the patients with other personality disorders. Furthermore, the psychotic-like schizotypal symptoms correlated positively with the CSF HVA concentrations. These results suggest a central dopaminergic dysfunction associated with the psychotic-like symptoms of schizotypal personality disorder.

Adult↗

Alzheimer's-disease-related protein in geriatric schizophrenic patients with cognitive impairment.

The authors compared Alz-50 immunoreactivity in the brain tissue of nine cognitively impaired elderly schizophrenic patients and 13 elderly comparison subjects, both without neuritic plaques or neurofibrillary tangles, and 13 patients with Alzheimer's disease. Alz-50 reactivity was absent in the schizophrenic patients, indicating that geriatric, cognitively impaired patients are unlikely to display the pathology of Alzheimer's disease.

Aged↗

Schizophrenia-related and affective personality disorder traits in relatives of probands with schizophrenia and personality disorders.

OBJECTIVE: The possible heterogeneity of the schizophrenia-related personality disorder traits associated with DSM-III criteria for schizotypal personality disorder was investigated using the family history method. A familial relationship to schizophrenia was hypothesized for schizophrenia-related personality disorder traits without coexisting affective personality disorder traits, pure schizophrenia-related personality disorder traits. Alternatively, a familial relationship with borderline personality disorder was hypothesized for schizophrenia-related personality disorder traits with comorbid affective personality disorder traits. METHOD: Criteria for schizophrenia-related and affective personality disorder traits were used to assess the 588 nonpsychotic first-degree relatives of 55 chronic schizophrenic probands and 67 probands with personality disorders. The probands with one or more DSM-III personality disorders were categorized as having schizotypal personality disorder without borderline personality disorder (pure schizotypal personality disorder), borderline personality disorder without schizotypal personality disorder (pure borderline personality disorder), both disorders, or neither. RESULTS: The morbid risk of all cases of schizophrenia-related personality disorder traits was higher in relatives of probands with schizophrenia and pure schizotypal personality disorder than in relatives of probands with neither schizotypal nor borderline personality disorder; however, it differed only slightly from that observed in the relatives of probands with both schizotypal and borderline personality disorders and pure borderline personality disorder. In contrast, the risk of pure schizophrenia-related personality disorder traits was higher in relatives of probands with schizophrenia and pure schizotypal personality disorder, while the risk of coexisting schizophrenia-related and affective personality disorder traits was lower in both of these groups than among the relatives of probands with both schizotypal and borderline personality disorders and pure borderline personality disorder. CONCLUSIONS: These results offer preliminary indications that schizotypal personality disorder features present without comorbid affective personality disorder traits may more specifically characterize the personality characteristics familially related to schizophrenia. Furthermore, they indicate that schizotypal personality disorder features as currently defined are found in relatives of patients other than those with schizophrenia or schizotypal personality disorder.

Adult↗

Serotonin function and treatment response to clozapine in schizophrenic patients.

OBJECTIVE: Clozapine is the only compound proven to be effective in the 20% of schizophrenic patients refractory to treatment with conventional neuroleptics. Although its mechanism of action has not been elucidated, clozapine appears, in contrast to most conventional neuroleptics, to be a potent serotonin (5-HT) antagonist. This study hypothesized that 5-HT function is increased in patients who benefit from clozapine treatment relative to patients who fail to improve on it. METHOD: The 5-HT receptor agonist m-chlorophenylpiperazine (MCPP) was used as a probe to examine 5-HT function. MCPP (0.35 mg/kg p.o.) was administered in a placebo-controlled design after a 3-week drug-free period to 19 schizophrenic patients. ACTH, prolactin, body temperature, behavior, and MCPP blood level were measured. Patients were then treated with a conventional neuroleptic, and, having failed to respond to it, were treated with clozapine for 5 weeks (up to 600 mg/day). RESULTS: Patients who responded to clozapine had significantly higher ACTH responses to MCPP during the drug-free state than the patients who failed to benefit from clozapine. Moreover, the degree of improvement with clozapine, particularly the improvement in psychotic symptoms, was strongly correlated with the magnitude of MCPP-induced ACTH release. Other MCPP-induced responses and MCPP blood level were similar for the two groups and did not correlate with the degree of symptomatic improvement with clozapine. CONCLUSIONS: Results of this study suggest that MCPP-induced ACTH release, and by inference 5-HT receptor function, may be increased in patients who benefit from treatment with clozapine relative to patients who fail to improve on this drug.

Adrenocorticotropic Hormone↗

Chronic ethanol administration sensitizes hippocampal neurons to neurotoxicity of N-methyl-D-aspartic acid.

The hyperexcitability observed following ethanol withdrawal in dependent animals is thought to be related to increased sensitivity of glutamate receptors. This may predispose to 'excitotoxic' neural damage. The aim of this study was to test this hypothesis by intrahippocampal injection of N-methyl-D-aspartic acid (NMDA) in ethanol-dependent rats and to quantify brain damage using enzymic neuronal markers, viz. choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD). Specific activity of GAD but not ChAT was found to be significantly decreased in hippocampi of ethanol-dependent animals following injection of NMDA, suggesting that chronic ethanol administration sensitizes GABAergic neurons to the toxic effects of excitatory amino acid transmitters.

Alcoholism↗

Predictors of response to neuroleptic treatment in schizophrenia.

Baseline symptom severity, early reduction in symptom severity, initial subjective response to neuroleptic treatment, the degree of brain atrophy, and early changes in pHVA levels appear to predict treatment outcome in schizophrenic patients. Computerized EEG results, neuropsychological and neurophysiologic tests, and baseline pHVA concentrations require further examination. Only a limited proportion of variance in treatment response, however, could be explained by either of the nine predictors alone or combined. Therefore, further research is necessary to discover yet unidentified determinants of treatment response. Future studies should test the validity and reliability of these five promising predictors in large groups of male and female patients, employ high standards for assessment reliability of clinical parameters, and use absolute rating scores on psychopathology as well as functional scales for the definition of good and poor treatment response. Furthermore, the statistical approach for data analysis should take in consideration the need for appropriate corrections when multiple correlations are performed and should test the extent to which these predictors are interdependent.

Antipsychotic Agents↗

Effect of m-chlorophenylpiperazine on plasma homovanillic acid concentrations in healthy subjects.

In view of the abundant anatomical and functional interactions between serotonin and dopamine systems, this study examined the effect of the serotonin agonist, m-chlorophenylpiperazine (mCPP) on plasma concentrations of the dopamine metabolite, homovanillic acid. Plasma prolactin levels, body temperature, and mCPP blood level were also measured. mCPP (0.35 mg/kg) and placebo were administered orally to 10 healthy men in a randomized double-blind design. Variables were measured for 210 min after administration of capsules. mCPP raised prolactin and temperature as compared to placebo, but did not affect plasma homovanillic acid concentrations. Results suggest that mCPP does not alter dopamine function.

Administration, Oral↗

The mitochondrial tRNA(Leu)(UUR)) mutation in MELAS: a model for pathogenesis.

The A----G transition at nucleotide 3243 of the mitochondrial tRNA(Leu)(UUR)) gene has been associated with MELAS, a maternally-inherited mitochondrial disorder. We recently transferred mitochondria harboring this mtDNA mutation into a human cell line devoid of endogenous mtDNA (rho degrees cells), and showed: (1) decreased rate of synthesis and of steady-state levels of mitochondrial translational products, (2) reduced respiratory chain function and (3) increased amounts of a novel unprocessed RNA species (termed by us RNA 19) derived from transcription of the 16S rRNA + tRNA(Leu)(UUR) + ND 1 genes. Because RNA 19 contains rRNA sequences, we propose that this molecule is incorporated into mitochondrial ribosomes, and interferes disproportionately with mitochondrial translation, thereby causing the phenotypic changes associated with MELAS.

Brain Diseases, Metabolic↗

Prenatal diagnosis for the cystic fibrosis mutation 1717-1, G-->A using arms.

A family carrying two cystic fibrosis mutations, delta F508 and 1717-1, G-->A, requested prenatal diagnosis. In order to eliminate the need for labelling of allele-specific oligonucleotides and to simplify the analysis, 1717-1, G-->A was detected using an ARMS (amplification refractory mutation system) method (Newton et al., 1989). Fetal DNA was obtained by chorionic villus sampling (CVS) and the ARMS technique was used to exclude the 1717-1, G-->A mutation. The fetus was found to be heterozygous for the delta F508 mutation. ARMS is a simple, quick, non-radioactive method suitable for detecting DNA mutations in various clinical situations.

Adenine↗

Cardiomyopathy in cattle induced by residues of the coccidiostat maduramicin in poultry litter given as a feedstuff.

An experimental feeding trial was conducted in order to substantiate an hypothesis on the aetiology of a previously unrecorded cardiomyopathic syndrome in beef cattle in Israel. It was believed that residues of the ionophore maduramicin (Cygro; American Cyanamid) in poultry litter fed to cattle, after the maduramicin had been incorporated into broiler feed as a coccidiostat, were the cause of the cardiomyopathy. Three groups of 5 heifers were fed for several weeks (1) poultry litter from a field case, containing 4.8 ppm maduramicin; (2) poultry litter to which maduramicin was added to give a concentration of 12 ppm; (3) poultry litter with no maduramicin (control). Clinical, biochemical, necropsy and histopathological findings showed that maduramicin residues are cardiotoxic, even at the lower level of maduramicin fed, which is commonly encountered in poultry litter in Israel.

Animal Feed↗

Empirical assessment of the factorial structure of clinical symptoms in schizophrenia: negative symptoms.

The factor structure of the Scale for the Assessment of Negative Symptoms (SANS) was examined in a confirmatory factor analysis that used the LISREL procedure. Four models of negative symptom factors were tested in 130 hospitalized schizophrenic patients. A three-factor model of diminished expression, social dysfunction, and disorganization generated by the authors yielded a superior fit to the data relative to the two-factor model of Liddle (1987b) and a unifactorial severity model. A four-factor model based on the original subscale formulation of the SANS failed to fit the data.

Adult↗

Deterioration on the Blessed test in Alzheimer's disease: longitudinal data and their implications for clinical trials and identification of subtypes.

One hundred eleven patients with probable Alzheimer's disease (AD) were given the Blessed test (BT) of information, memory, and concentration (scored 0-33) at 6-month intervals over periods of 6-96 months. For each patient, the change in the total BT score between pairs of visits at 6- and 12-month intervals was measured. Mean deterioration scores over 6 and 12 months were 2.2 (SD = 3.2) and 4.1 (SD = 4.1) points, respectively. There was no significant correlation between degree of dementia on the BT and the rate of deterioration. Gender, age of onset, and family history had no significant effect on the rate of deterioration. The implications of the results for treatment trials and investigations of clinical heterogeneity are discussed.

Adult↗

Nocturnal growth hormone secretion in schizophrenic patients and healthy subjects.

Plasma growth hormone concentrations were measured at hourly intervals between 10 p.m. and 8 a.m. the next morning in 15 drug-free chronic schizophrenic male inpatients and 14 healthy males. Growth hormone secretion was significantly lower in the patients as compared with the controls. Growth hormone release peaked around 1 a.m. in the controls, but a growth hormone peak was absent in the patient group. Increased dopamine activity, increased serotonin activity, or both could explain the absence of a nocturnal growth hormone surge in the schizophrenic patients.

Adult↗

Serotonin function in schizophrenia: effects of meta-chlorophenylpiperazine in schizophrenic patients and healthy subjects.

This study examined serotonin (5-hydroxytryptamine; 5HT) receptor responsivity in 22 chronic schizophrenic patients and 17 healthy control subjects. The 5HT agonist meta-chlorophenylpiperazine (MCPP) was used as a probe of serotonergic function. MCPP (0.35 mg/kg) or placebo was administered orally after a 3-week drug-free period in a randomized double-blind design. Hormonal (adrenocorticotropic hormone and prolactin), temperature, and behavioral responses and MCPP blood levels were assessed for 210 minutes after administration of the capsules. The schizophrenic patients had blunted temperature responses compared with those of the healthy control subjects: MCPP raised body temperature in the control subjects, but not in the patients. Behavioral responses also differed in the two groups: MCPP increased the total Brief Psychiatric Rating Scale (BPRS) score in the control subjects and tended to decrease it in the patients. In patients, MCPP decreased the BPRS psychosis subscore. Hormonal responses did not differ significantly in the two groups. These findings suggest that further exploration of 5HT function in schizophrenia is warranted.

Adrenocorticotropic Hormone↗

Inactivated hepatitis A vaccine: a safety and immunogenicity study in health professionals.

The safety and immunogenicity of an inactivated hepatitis A vaccine (HM175 strain) were evaluated in 150 seronegative health professionals. The age range was 21-65 years and the mean age was 30 years. The vaccine was administered at a dose of 720 ELISA units (EU) to 73 vaccinees at 0, 1 and 6 months, and to 77 vaccinees at 0, 1 and 12 months. The seroconversion rates were 88 and 90% in the two groups, respectively, one month after the first inoculation and 99 and 100% one month after the second inoculation. The geometric mean antibody titres were similar in both groups, exceeding 3000 mIU/ml one month after the third inoculation. The vaccine was well tolerated. The most frequent side effect was transient soreness at the site of the inoculation. No serious adverse reactions were observed. The study demonstrated that the HM175 inactivated hepatitis A vaccine was safe and highly immunogenic.

Adult↗