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Biomedical subjects

R S Kahn

Publications and source records attributed to R S Kahn.

At least 91 records · Page 5Linked to original sources
PubMed1999

The scope of unmet maternal health needs in pediatric settings.

OBJECTIVE: Previous work has focused attention on the prevalence of specific maternal health problems known to affect children, such as smoking or depression. However, the cumulative health burden experienced by mothers and the potential for a practical pediatric health services response have not been examined. The aims of this study were to characterize: 1) the prevalence and cumulative burden of maternal health behaviors and conditions, 2) maternal access to a source of comprehensive adult primary care, and 3) maternal perceptions of a pediatric role in screening and referral. METHODS: We surveyed 559 consecutive women bringing a child 18 months of age or less to one of four pediatric primary care sites between July 1996 and May 1997. The pediatric sites included one outpatient program in an academic hospital, one in a community health center, and two in-staff model practices of a managed care organization (these last two were combined for analysis). The self-administered questionnaire contained previously validated questions to assess health behaviors and conditions (smoking, alcohol abuse, depression, violence, risk for unintended pregnancy, serious illness, self-reported health) and access to care (regular source, regular provider, health insurance, care delayed or not received). Maternal attitudes toward a pediatric role in screening and referral were also elicited. RESULTS: In the three settings, response rates ranged from 75% to 84%. The average age of the women ranged from 25.1 to 32. 1 years and the average age of the children ranged from 6.5 to 8.0 months. Across the settings, the percentage of women reporting at least one health condition (66%-74%) was similarly high, despite significant demographic differences among sites. Many women reported more than one condition (31%-37%); among all women who smoked, 33% also screened positive for alcohol abuse, 31% for emotional or physical abuse, and 48% for depression. Access to comprehensive adult primary care was variable with 23% to 58% of women reporting one or more barriers depending on the site. Across all sites, >85% of mothers reported they would "not mind" or "would welcome" a pediatric role in screening and referral. CONCLUSIONS: Two-thirds of women bringing their children for pediatric care had health problems regardless of the site of care. Many women also reported substantial barriers to comprehensive health care. Most women reported acceptance of a pediatric role in screening and referral. Given the range and depth of maternal health needs, strategies to connect or reconnect mothers to comprehensive adult primary care from a variety of pediatric settings should be explored.

Adult↗
PubMed1999

New perspectives in the diagnosis of hepatitis C.

Since the identification and molecular characterization of the non-A, non-B hepatitis virus (HCV) in 1989, a variety of diagnostic tests based on the detection of hepatitis virus antibodies or HCV RNA in the serum have been developed and refined. The enzyme-linked immunosorbent assays (ELISAs) and the recombinant immunoblot assays (RIBAs) exhibit improved sensitivity and specificity for HCV antibodies compared with their predecessors, and the ELISA-3 is at the forefront of HCV screening. Furthermore, the advent of molecular assays that employ quantitative reverse-transcriptase polymerase chain reaction to detect HCV RNA has allowed clinicians to track the natural history of HCV and to monitor the progress of therapy. A role for further refinement of an HCV diagnosis using tests to determine genotype, subtype, and quasispecies is explored. In addition, the role of liver biopsy and non-invasive markers of histologic status are placed into the context of patient prognosis. This article reviews the state-of-the-art tests and assays developed for the diagnosis and management of HCV infection.

Enzyme-Linked Immunosorbent Assay↗
PubMed1998

[Diagnostic imaging techniques in psychiatry].

Morphological and functional abnormalities have been found in several psychiatric diseases, including schizophrenia, schizophreniform disorder, manic-depressive disorder, obsessive compulsive disorder, posttraumatic stress disorder, and panic disorder. Most research concerned schizophrenia. Altered volumes of the ventricles, cortical gray matter, basal nuclei, thalamus and limbic structures have been reported. Altered activity was found in several cortical and subcortical brain structures, in particular the frontal cortex, during cognitive and pharmacological challenge. Disease progress, genetic and environmental factors appear to influence the brain abnormalities. The specificity of the findings is still limited. The use of imaging techniques in the psychiatric clinic is still restricted. Notwithstanding these limitations, focus in psychiatry research has been switched from the question if brain abnormalities exist to where they are, of what they consist and where they originated.

Animals↗
PubMed1998

Blunted cortisol response to a psychosocial stressor in schizophrenia.

Schizophrenia is considered a neurodevelopmental disorder in which vulnerability to stress may be a contributing factor. Coping is an important psychological component of stress processing, and the hypothalamic-pituitary-adrenal system (HPA system) is one of the biological components of stress adaptation. Disturbances of either of these components may make schizophrenic patients more vulnerable to develop a psychosis under stressful circumstances. In this study, 10 schizophrenic men were compared with 10 healthy male controls in their response to a psychosocial stressor, consisting of a public-speaking task. Heart rate was monitored as a measure of autonomic arousal. HPA responses were assessed by measuring salivary cortisol. Coping skills were measured by using the Utrecht Coping List and the Ways of Coping Checklist. The stress of speaking in public increased the heart rate in both patients and controls; however, a significant cortisol response was found in the controls, but not in the schizophrenic patients. The patients used more passive and avoidant coping strategies than controls. The findings provide support for the notion that schizophrenic patients have an impaired ability to adapt, both psychologically and biologically, to their environment.

Adaptation, Psychological↗
PubMed1998

Hostility is associated with a heightened prolactin response to meta-chlorophenylpiperazine in abstinent cocaine addicts.

The prolactin (PRL) response to the administration of serotonin (5HT) agonists is an index of central nervous system 5HT activity. This index is blunted in association with hostile aggression in personality and depressive disorder patients without substance abuse. We tested whether the PRL response to the oral administration of the partial 5HT agonist meta-chlorophenylpiperazine (MCPP), 0.35 mg/kg, was associated with a measure of trait hostility, the Buss Durkee Hostility Inventory (BDHI), in cocaine addicts who were completing a 3-week detoxification and rehabilitation program. We also tested whether the cocaine addicts differed from healthy volunteers on their PRL, cortisol (CORT) or temperature responses to MCPP. The PRL response to MCPP was positively associated with the total score on the BDHI. There were, however, no differences in the neuroendocrine or temperature responses to MCPP between the cocaine-dependent group and the healthy volunteers once age effects were controlled for.

Adult↗
PubMed1998

Tactile stimulation during finger opposition does not contribute to 3D fMRI brain activity pattern.

Functional magnetic resonance imaging (fMRI) is a new, non-invasive technique to localize brain activity with a high spatial resolution. Activation of the motor cortex by sequential movement of the thumb to the fingers has been used extensively to validate the fMRI technique. This task, however, combines motor activity (movement of thumb and fingers) with tactile stimulation (touching the finger with the thumb). In this study we examined the contribution of tactile stimulation to the activity pattern. Nine healthy subjects were instructed to touch the fingers with the thumb in a first task, and repeat this movement without touching the fingers in a second task. Comparison of the two activity patterns did not result in a significant difference. Therefore we concluded that the pattern of activity associated with a fingertapping task is not influenced by tactile stimulation, but is caused primarily by motor activation and possibly by proprioceptive activity.

Adult↗
PubMed1998

Phase navigator correction in 3D fMRI improves detection of brain activation: quantitative assessment with a graded motor activation procedure.

Motion poses severe problems for BOLD fMRI, particularly in clinical studies, as patients exhibit more involuntary movements than controls. This study focuses on the merits of a motion correction technique incorporated in multishot fMRI scans, so-called phase navigator correction. The technique entails real-time assessment and off-line elimination of signal fluctuations caused by subject motion. The purpose of this study was to quantify and characterize the effect of this type of improvement on 3D fMRI brain activity maps. For imaging, the 3D PRESTO method was used, with a relatively simple finger opposition task. The followed strategy was guided by the notion that application of any fMRI imaging tool in clinical studies requires several qualities, such as high and spatially homogeneous sensitivity to brain activity, and low sensitivity to motion. A graded motor activation protocol in 10 healthy subjects revealed that image stability was improved by approximately 20%, by the use of phase navigator correction. As a result, sensitivity for task-related BOLD signal change was enhanced considerably in the brain activity maps. Implications for use of this fMRI technique in patient studies are discussed.

Adult↗
PubMed1998

The effects of low dose ketamine on sensory gating, neuroendocrine secretion and behavior in healthy human subjects.

Recently, much interest has been given to the role of glutamatergic N-methyl-D-aspartate receptors (NMDA) in sensory gating, such as prepulse inhibition (PPI) and reduction of the P50 evoked response potential (ERP). Currently, mainly animal data are available describing the role of NMDA receptors in these stimulus evaluation processes. Human data are virtually lacking and are potentially important, for instance for the understanding of sensory gating deficits observed in schizophrenia. Therefore, the effects of the NMDA antagonist ketamine, in a dose of 0.3 mg/kg i.v., on concurrent assessment of PPI and P50 reduction was studied in 18 healthy male volunteers. Ketamine was administered in a pseudo-steady state model with a subacute loading dose. In addition, the effects of ketamine on behavior, vital signs, homovanillic acid (HVA) plasma levels and secretion of cortisol and luteinizing hormone (LH) were also determined. Ketamine did not significantly alter PPI or the reduction of the P50 ERP. A small but significant increase in Brief Psychiatric Rating Scale (BPRS) total scores and BPRS composite scores "thinking disorder" and "withdrawal/retardation" was observed. Several subjects experienced visual perceptional alterations, but complex hallucinations did not occur. Ketamine induced mild analgesia and coordination problems. In addition, ketamine induced a marked rise in cortisol secretion, while LH secretion was not affected. Finally, systolic and diastolic, blood pressure and heart rate increased during ketamine infusion. Although in humans NMDA receptors may not be involved in the regulation of PPI and P50 reduction, the most likely explanation for the lack of effect of ketamine on these sensory gating paradigms is the dose used in this experiment. However, using a higher dose is hampered by the aspecificity of racemic ketamine. Future studies should use the enantiomer S-ketamine, which is more specific to NMDA receptors, to evaluate the involvement of NMDA receptors in these neurophysiological processes further.

Adult↗
PubMed1998

The partial NMDA agonist D-cycloserine stimulates LH secretion in healthy volunteers.

D-Cycloserine, a partial agonist of the glycine recognition site of the N-methyl-D-aspartate (NMDA) receptor, may serve as a probe for human cerebral NMDA receptor function. Since NMDA receptors are involved in neuroendocrine secretion, changes in pituitary secretion in response to D-cycloserine administration could serve as a model for NMDA receptor activity. The effects of an oral dose of 500 mg D-cycloserine were assessed in a neuroendocrine challenge paradigm in 20 healthy male volunteers, using a double-blind, randomized placebo-controlled crossover design. Luteinizing hormone (LH) and cortisol secretion was studied, since preclinical studies indicate that these hormones increase in response to NMDA receptor stimulation. Furthermore, plasma homovanillic acid (HVA) secretion was studied, as NMDA receptors are suggested to be involved in the regulation of dopaminergic neurotransmission. D-cycloserine was readily absorbed and did not induce side-effects or changes in vital signs and mood scores. D-Cycloserine stimulated LH secretion and induced a significant rise of the area under the plasma concentration time curve of LH. D-Cycloserine did not stimulate cortisol or plasma HVA secretion. These neuroendocrine effects suggest that D-cycloserine may be used to assess human NMDA receptor function in cerebral disorders, such as schizophrenia.

Adult↗
PubMed1998

Control of renal factors in plasma homovanillic acid measurements.

To identify and control renal factors affecting plasma homovanillic acid (HVA), a dopamine metabolite and an indicator of brain dopamine activity in clinical research, nine healthy subjects were studied on 5 nonconsecutive days. First study day was the baseline and on the other days base, salt, water, or probenecid loads were given. On each day serial concentrations of HVA and serotonin metabolite 5-hyroxyindoleacetic acid (HIAA), another organic anion, in plasma were measured. Results suggested that base, salt, and water loads did not affect plasma concentrations of either metabolite. Probenecid, which partially blocks renal organic anion transport, induced similar increases in plasma HVA and HIAA. When plasma HVA:HIAA ratio was used to control for the effect of probenecid, differences between baseline and probenecid days were no longer significant. Results suggest that HVA and HIAA are similarly handled by the kidney and that simultaneously measured plasma HIAA could be used to distinguish renal influences in plasma HVA studies.

Adult↗
PubMed1998

Partial volume decrease of the thalamus in relatives of patients with schizophrenia.

OBJECTIVE: The authors' goal was to compare the thalamic, total brain, and intracranial volumes of patients with schizophrenia, their healthy siblings, and normal comparison subjects. METHOD: Magnetic resonance imaging (MRI) brain scans were obtained for 32 same-sex siblings who were discordant for schizophrenia and 32 matched normal comparison subjects. RESULTS: Mean total thalamic volume, corrected for total brain volume, was significantly different among affected siblings, unaffected siblings, and comparison subjects. Thalamic volume was smallest in the patients; thalamic volume in their siblings was smaller than that of comparison subjects but larger than that of the patients with schizophrenia. CONCLUSIONS: These results suggest that healthy siblings of patients with schizophrenia partially share the thalamic abnormalities of their affected relatives.

Brain↗
PubMed1998

Intermittent neuroleptic treatment and risk for tardive dyskinesia: Curaçao Extrapyramidal Syndromes Study III.

OBJECTIVE: The authors examined the association between three lifetime medication variables (cumulative amount of neuroleptics, number of interruptions in neuroleptic treatment, cumulative amount of anticholinergics) and the occurrence and severity of tardive dyskinesia. METHOD: The study was conducted in the only psychiatric hospital of a well-defined catchment area (the Netherlands Antilles). For all patients who had a history of taking neuroleptics for at least 3 months and were currently using neuroleptics (N = 133, mean age = 51.5 years), the presence and severity of tardive dyskinesia were measured with the Abnormal Involuntary Movement Scale. RESULTS: Of the three lifetime medication variables, only the number of neuroleptic interruptions was significantly related to tardive dyskinesia. The risk of tardive dyskinesia was three times as great for patients with more than two neuroleptic interruptions as for patients with two or fewer interruptions. CONCLUSIONS: This finding supports the schizophrenia protocol of long-term neuroleptic treatment rather than targeted or intermittent neuroleptic treatment.

Aged↗
PubMed1997

The inter-relationships of tardive dyskinesia, parkinsonism, akathisia and tardive dystonia: the Curaçao Extrapyramidal Syndromes Study II.

A study of the four extrapyramidal syndromes (EPS), tardive dyskinesia, parkinsonism, akathisia and tardive dystonia, was performed in the Netherlands Antilles, a well-defined catchment area with only one psychiatric hospital. The population under study (N = 194; mean age 53.1) was mainly Afro-Caribbean, and most patients were chronic. The severity of each EPS was measured with valid and reliable rating scales. The purpose was to study both the strength of the inter-relationships of EPS and the prevalence of combinations of EPS. The inter-relationships between the EPS were analyzed by means of logistic regression. The adjusted odds ratios between the various EPS revealed strong connections between the hyperkinetic syndromes (tardive dyskinesia, tardive dystonia and akathisia). Parkinsonism was found to be inversely related to tardive dyskinesia and to tardive dystonia. Almost 30% of the patients suffered from two or more EPS. The highest prevalence rates of combinations were: tardive dyskinesia combined with parkinsonism 12.9%, tardive dyskinesia combined with tardive dystonia 9.8%, and tardive dyskinesia combined with akathisia 5.2%. Our findings show a strong positive correlation between hyperkinetic forms of EPS. Furthermore, chronic psychiatric inpatients regularly suffer from combinations of EPS. Different treatment strategies are suggested for various combinations of EPS.

Akathisia, Drug-Induced↗
PubMed1997

Behavioral and neuroendocrine effects of the partial NMDA agonist D-cycloserine in healthy subjects.

The effect of D-cycloserine, a partial agonist of the N-Methyl-D-Aspartate (NMDA) receptor, were assessed in a (neuroendocrine) challenge paradigm to to examine NMDA systems in male healthy volunteers, using a double-blind, placebo-controlled crossover design. Oral D-cycloserine (15, 50, and 150 mg) was readily absorbed and its plasma concentration increased dose-dependently. Behavioral and hormonal responses were measured for 240 minutes after administration of the drug. D-cycloserine was well tolerated and did not induce side-effects according to the Visual Analog Scales (VAS), the Brief Psychiatric Rating Scale (BPRS) and the Adverse Events Checklist (AEC) & codes. D-cycloserine failed to elicit a neuroendocrine response as evaluated by cortisol, prolactin, and luteinizing hormone (LH) plasma levels. The present result suggests that D-cycloserine can readily be administered to healthy volunteers but that, in the dosages used, neuroendocrine secretion fails to serve as a model for testing NMDA receptor function in humans.

Adult↗
PubMed1997

Schizophrenia in Surinamese and Dutch Antillean immigrants to The Netherlands: evidence of an increased incidence.

BACKGROUND: Reports of an increased incidence of schizophrenia in Afro-Caribbean immigrants to the UK are a matter of much debate. It is of interest, therefore, that in the 1970s and 1980s many immigrants from Surinam and The Netherlands Antilles have settled in The Netherlands. The purpose of our study was to compare the risk of a first admission for schizophrenia for Surinamese- and Antillean-born persons aged 15-39 years to that for their Dutch-born peers in the period 1983-1992. METHODS: We used data from the Dutch psychiatric registry. Age-adjusted relative risks were calculated using Poisson regression analysis. RESULTS: The risk for the immigrants was found to be three to four times higher than that for the Dutch-born. Age-adjusted relative risks were significantly higher for male than for female immigrants. CONCLUSIONS: The results provide evidence of an increased incidence in these immigrant groups and support similar findings on Afro-Caribbeans in the UK. Migration from Surinam was on such a large scale that selective migration of persons at risk for the disorder is unlikely to account entirely for these findings.

Adolescent↗
PubMed1996

The prevalence of tardive dystonia, tardive dyskinesia, parkinsonism and akathisia The Curaçao Extrapyramidal Syndromes Study: I.

A prevalence study of extrapyramidal syndromes was conducted among all psychiatric inpatients of the Netherlands Antilles (n = 194; mean age 53.1). The Netherlands Antilles are very suitable for epidemiological research as it is a well-defined catchment area with only one psychiatric hospital and a health care system based on western principles. In this mainly chronic population, the prevalence was measured of tardive dystonia, tardive dyskinesia, parkinsonism and akathisia using respectively the Fahn-Marsden rating scale, the Abnormal Involuntary Movement Scale, the Unified Parkinson Disease Rating Scale and the Barnes Akathisia Rating Scale. The prevalence numbers were for tardive dystonia 13.4%, tardive dyskinesia 39.7%, parkinsonism 36.1%, akathisia 9.3% and pseudoakathisia 12.9%. The most important conclusions were: (1) The prevalence of tardive dystonia was higher than reported in most other studies and (2) extrapyramidal syndromes are very common in this predominantly Negroid population, with three out of four patients suffering of one or more extrapyramidal syndromes.

Adult↗