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Biomedical subjects

B Kirkpatrick

Publications and source records attributed to B Kirkpatrick.

At least 91 records · Page 5Linked to original sources
PubMed1992

Brain morphology and schizophrenia. A magnetic resonance imaging study of limbic, prefrontal cortex, and caudate structures.

We used magnetic resonance imaging to examine the morphologic characteristics of the amygdala/hippocampus, prefrontal cortex, and caudate nucleus in 29 healthy volunteers matched for age, gender, and head of household socioeconomic status and 44 patients with chronic schizophrenia. Total volumes of these structures were determined from 3-mm contiguous coronal sections. Schizophrenic patients, compared with healthy controls, had significantly smaller right and left amygdala/hippocampal complex volumes, smaller right and left prefrontal volumes, and larger left caudate volumes. A secondary analysis revealed reductions in the right and left amygdala and the left hippocampus. In addition, prefrontal white matter, but not gray matter, was reduced in the schizophrenic patients. Moreover, the right white matter volume in schizophrenic patients was significantly related to right amygdala/hippocampal volume (r = .39), data that provide preliminary support for a hypothesis of abnormal limbic-cortical connection in schizophrenia. We studied the implications of these data for the pathophysiology of schizophrenia.

Adult↗
PubMed1992

The concept of supersensitivity psychosis.

The hypothesis that chronic neuroleptic treatment may induce relapse in some schizophrenic patients has received considerable attention. This effect, usually called supersensitivity psychosis, has been attributed to neuroleptic-induced changes in mesolimbic or mesocortical dopaminergic receptors. However, research has not established that neuroleptics cause the proposed effect, and considerations of mechanism have not been separated from those of causation. The focus of research in this area should be the establishment or refutation of a causal relationship between chronic neuroleptic use and psychotic relapse.

Antipsychotic Agents↗
PubMed1991

Carbamazepine maintenance treatment in outpatient schizophrenics.

A double-blind crossover trial was used to evaluate carbamazepine as the sole maintenance treatment of chronic, nonmanic schizophrenic outpatients whose conditions had been stabilized with the use of neuroleptics prior to study. Criteria of treatment effectiveness included the number of patients relapsing and time to relapse over a 95-day neuroleptic-free period during which either carbamazepine or placebo was administered. Relapse was determined by the concordance of psychiatric ratings and independent clinical judgements indicating significant worsening. Results for 27 patients (13 receiving carbamazepine and 14 receiving placebo) involved in the first phase of this treatment comparison were nondifferentiating. Corroborating descriptive findings in the second phase were available for 14 of these patients. There was no evidence supporting the existence of a treatment-relevant subgroup defined by episodic dyscontrol phenomena.

Adult↗
PubMed1991

Chemotaxis of Pseudomonas syringae subsp. savastanoi Virulence Mutants.

Several mutants of Pseudomonas syringae subsp. savastanoi were tested for their ability to sense and respond to a chemotactic gradient in low concentrations of yeast extract. The mutants were deficient in one or both of the genes coding for the synthesis of the plant hormones indole-3-acetic acid (IAA) and isopentenyl adenosine. Mutations which resulted in the loss of IAA production were due to the loss of the entire plasmid containing the iaa operon or to an 18-kb deletion of the iaa region. Additional mutants tested were deficient in their ability to produce isopentenyl adenosine as a result of the loss of the ptz-bearing plasmid. In all cases, strains which had lost the ability to produce IAA exhibited enhanced motility of up to 2.5 times that of the wild type (IAA) in medium containing 0.01% yeast extract. No differences in motility were observed on medium containing lower concentrations of yeast extract. The presence or absence of the cytokinin plasmid and the presence or absence of inorganic nitrogen in the medium had no effect on the relative mobility of the strains.

Journal Article↗
PubMed1990

Anhedonia and the deficit syndrome of schizophrenia.

Schizophrenic outpatients with and without the deficit syndrome were administered Chapman's "psychosis proneness" scales. As hypothesized, deficit syndrome patients had higher scores on Social Anhedonia and Physical Anhedonia, but did not differ from nondeficit patients on Perceptual Aberration, Magical Ideation, or Impulsive Nonconformity. The differences between the two groups were not related to race, gender, age, socioeconomic status of family of origin, or drug treatment. These results support the validity of the deficit syndrome, and suggest that the Social Anhedonia and Physical Anhedonia scales may be useful in future studies of schizophrenia.

Adult↗
PubMed1990

The neural basis of the deficit syndrome of schizophrenia.

The deficit syndrome is a domain of schizophrenic psychopathology defined by the presence of primary negative symptoms that are enduring features of a patient's function between periods of relapse. Lesions of the putative neural circuit underlying social affiliation and social behavioral cues in nonhuman primates and other mammals cause behavioral impairments in animals that model the diminished social drive, poverty of speech, and blunted affect of the deficit syndrome. Components of this circuit include the amygdala, periamygdalar cortex, and part of the prefrontal cortex. Abnormal function of this functional circuit may underlie the deficit syndrome.

Amygdala↗
PubMed1990

Clinical correlates of the deficit syndrome of schizophrenia.

The authors propose using primary and enduring negative or deficit symptoms for dichotomizing schizophrenic patients into two groups, deficit and nondeficit. The validity of this approach was examined by comparing 17 deficit and 17 nondeficit patients for differences in premorbid adjustment and degree of neurological impairment. Deficit patients were characterized by poorer premorbid adjustment and greater neurological impairment. Neurological impairment was not related to premorbid adjustment in either group or in the total patient population. These findings support the utility of deficit symptoms for defining a more homogeneous subgroup of schizophrenia.

Adult↗
PubMed1990

Continuous versus targeted medication in schizophrenic outpatients: outcome results.

The authors report on the outcome of treatment of 116 outpatients with chronic schizophrenia who were assigned to a 2-year, single-blind course of treatment with either targeted or continuous medication. These patients were not restricted to those who were good candidates for a medication reduction strategy. Continuous medication was superior to targeted medication in preventing decompensations and hospitalizations and in extent of employment at 2 years. Other measures of psychopathology and functioning at 1 and 2 years did not differentiate the two groups of patients. The targeted approach achieved a substantial reduction in total medication through a reduction in the number of days of medication administration.

Adult↗
PubMed1989

Effect of neuroleptic withdrawal on plasma prolactin: a possible marker of receptor adaptation.

Stable schizophrenic and schizoaffective outpatients underwent abrupt withdrawal from a fixed dose of neuroleptic. Prolactin concentrations were determined preceding and following drug withdrawal. Basal prolactin concentrations were significantly lower 3, 4, or 5 days following drug withdrawal than on subsequent days. This rebound effect may be related to dopaminergic receptor changes in the tuberoinfundibular system that are induced by chronic neuroleptic administration.

Adult↗
PubMed1989

Alterations in sleep polygraphy after neuroleptic withdrawal: a putative supersensitive dopaminergic mechanism.

Although a number of studies have reported sleep disturbances following neuroleptic withdrawal, a full description of such changes in sleep architecture is not available. Polysomnographic, plasma prolactin, and clinical measurements were carried out in a small number of patients on chronic neuroleptic treatment and after drug withdrawal. Preliminary findings show that in these chronically treated schizophrenic patients with and without tardive dyskinesia (TD), abrupt neuroleptic withdrawal induces reductions in total sleep, rapid eye movement (REM) sleep, and plasma prolactin. Furthermore, an increase in delta sleep was observed only in patients without TD. The REM suppression occurred significantly earlier in TD patients compared to the non-TD schizophrenic patients. These changes were transient, and both sleep measures and plasma prolactin stabilized during the 2-4 weeks after withdrawal to levels somewhere between the values observed during chronic treatment and withdrawal (week 1) periods. As the withdrawal-induced exaggerated changes mimicked the dopamine agonist effect on these sleep and hormonal measures, one can hypothesize that the observed changes are due to unmasking of supersensitive dopamine receptors following drug cessation. Normalization of these receptors and/or adaptational changes in other nondopaminergic system(s) can hypothetically explain the eventual stabilization of these measures during the following weeks.

Adult↗
PubMed1989

Rating affective flattening from videotaped interviews.

Semistructured interviews with 28 schizophrenic patients were videotaped. The affective flattening section of the Scale for the Assessment of Negative Symptoms (SANS) was rated after each interview. At a later date, each videotape was rated by three raters as well as the interviewer. Reliability was estimated within and across rating conditions by intraclass correlation. Comparison of reliability scores across rating conditions indicated that the videotape medium had little effect on the ability of raters to rate affective flattening similarly.

Humans↗
PubMed1989

The Schedule for the Deficit syndrome: an instrument for research in schizophrenia.

The Schedule for the Deficit Syndrome (SDS) is an instrument for categorizing schizophrenic patients into those with and those without the deficit syndrome. In a study of 40 schizophrenic patients diagnosed by DSM-III criteria, raters using the SDS demonstrated good interrater reliability for this categorization, as well as for individual negative symptoms and a rating of global severity.

Affective Symptoms↗
PubMed1989

Diazepam treatment of early symptoms of schizophrenic relapse.

In an open trial, nine drug-free schizophrenic patients received oral diazepam, 10 to 40 mg/day, for the treatment of early symptoms of relapse. Diazepam treatment led to a return of the patient's usual condition in seven of 11 episodes.

Administration, Oral↗
PubMed1989

Oculomotor abnormalities and their clinical correlates in schizophrenia.

Smooth pursuit eye movements (SPEMs) have been consistently found to be abnormal in the majority of schizophrenic patients. The traditional SPEM measurement technique, however, fails to inform us about the underlying oculomotor deficit in these patients, since it remains a non-specific and a global oculomotor measure. A number of diverse clinical features such as tardive dyskinesia (TD) or negative symptoms correlate with the SPEM abnormality. Other eye movement abnormalities such as fixation difficulties, increased "volitional" saccadic latency and saccadic distractibility in anti-saccade paradigm have also been noted in schizophrenic patients. Still, it remains unclear how these different eye movement measures relate with each other and with the traditional SPEM measure, the presence of which is so widely described in schizophrenia. The advantage of some newer oculomotor paradigms is their functional specificity and the degree to which their biology is known. To further address these issues and to search for clinical correlates of various eye movement abnormalities found in schizophrenia, we have developed a battery of oculomotor measures to be administered to a large number of clinically well described schizophrenic patients and normal controls. The results from a preliminary analysis of a relatively small number of subjects are presented here, thus limiting the scope of possible conclusions. But, these results do indicate that this technique of studying multiple paradigms for oculomotor control in schizophrenia may prove to be fruitful.

Eye Movements↗
PubMed1988

Cloned riboprobe for detection of a mycoplasmalike organism.

A [32P]-labeled single stranded-RNA probe (riboprobe) was constructed with plasmid vector pSP64 and used to detect and specifically identify an uncultured pathogenic mycoplasmalike organism in infected host. The riboprobe was more sensitive and reliable than complementary double stranded-DNA probe in detection of western X mycoplasmalike organism. When concentration of a double stranded-DNA probe was increased, nonspecific hybridization signal was observed with nucleic acid from healthy plants and from plants infected by other mycoplasmalike organisms. In contrast, sensitivity of detection with the complementary riboprobe was increased at elevated probe concentrations without nonspecific hybridization.

Cloning, Molecular↗