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Biomedical subjects

B Kirkpatrick

Publications and source records attributed to B Kirkpatrick.

At least 73 records · Page 4Linked to original sources
PubMed1994

Olfactory bulbectomy decreases social behavior in male prairie voles (M. ochrogaster).

Prairie voles (Microtus ochrogaster) are social rodents that show characteristics of monogamy including high levels of social behavior and male parental care. Behavioral studies of prairie voles have implicated chemosignals in the control of various components of social behavior and reproduction. In the present study, the role of the olfactory system in male behavior was examined following surgical removal of the olfactory bulbs. Decreases in measures of sexual, paternal, and other social behaviors were observed following bilateral olfactory bulbectomy, but not unilateral or sham bulbectomy. Some bilaterally bulbectomized males also showed a stereotypy, but this probably did not account for the changes in social behaviors.

Animals↗
PubMed1994

Psychosis-proneness and verbal memory in a college student population.

Previous research has revealed numerous neuropsychological deficits in schizophrenics. Research on individuals with schizotypal personality features has also demonstrated similar neuropsychological deficits. However, the latter literature is limited in scope. This study examined verbal memory function in psychometrically identified (Chapman Scales) psychosis-prone college students (n = 409). Subjects were administered a standard verbal memory procedure (Logical Memory; Wechsler Memory Scale-Revised) as well as measures of verbal intelligence (Shipley Scale) and depression (Beck Depression Inventory). Results reveal no relationship between degree of schizotypic features and recall measures (immediate recall, delayed recall, and retention rate). Moreover, comparisons between low schizotypic subjects and those scoring at the extreme (greater than 2 standard deviations above the mean) also failed to reveal significant differences in recall. These results raise the possibility that memory deficits may be specific to schizophrenia and not the schizophrenia spectrum or that they are restricted to only those with the familial form of the disorder (i.e., those with family histories of schizophrenia).

Adolescent↗
PubMed1994

A review of the clinical presentation, laboratory features, antimicrobial therapy and outcome of 77 episodes of pneumococcal meningitis occurring in children and adults.

Seventy-seven episodes of pneumococcal meningitis in 69 patients were reviewed. Twelve (15.6%) episodes occurred in those over 60 years old, 14 (18.2%) in patients between 10 and 60 years, 22 (28.6%) in patients between 2 and 10 years and 29 (37.7%) in those under 2 years. Overall mortality was 13.0% (10/77) and age of > 60 years was significantly associated with mortality (P < 0.05). Twelve episodes resulted in disabilities, eight of which were in those under 2 years, and took the form of hearing impairment in nine. Many patients had predisposing conditions with aural pathology, malignancy and diabetes mellitus being commonest in those over 10 years of age and aural pathology, preceding viral infection, renal disease, sinusitis or recent lower respiratory tract infection commonest in those aged between 2 and 10 years. Three of five patients with recurrent meningitis had CSF leaks. The most common features at presentation were fits, irritability, diarrhoea, and bulging fontanelles in those under 6 months; vomiting, drowsiness and poor feeding in those between 6 months and 2 years; neck stiffness, vomiting and drowsiness in those between 2 and 10 years while neck stiffness, focal neurology, headache and vomiting were commonest in those over 10 years old. Fever was common in all age groups as were foci of infection outside the CSF, with chest infections being significantly associated with mortality (P < 0.05). Of the laboratory parameters measured, low platelets (< 100 x 10(9)/l and high blood urea (> 7 mmol/l) were associated with mortality (P < 0.05). Blood cultures grew Streptococcus pneumoniae in 79.7% patients. Seventy-four (96%) patients had CSF taken of which 81% had gram films which were positive and interpreted correctly as showing pneumococci. Pneumococci were grown in 87.8% CSF cultures and all were sensitive to penicillin but a single isolate was chloramphenicol resistant. Many different antimicrobial drugs were used but penicillin plus chloramphenicol was the most commonly employed after the results of CSF microscopy were known and penicillin alone after culture results were available. Penicillin mono-therapy was associated with a low mortality.

Adolescent↗
PubMed1994

Axon-sparing lesions of the medial nucleus of the amygdala decrease affiliative behaviors in the prairie vole (Microtus ochrogaster): behavioral and anatomical specificity.

The neural basis of affiliative behavior was examined in the prairie vole, a rodent that exhibits high levels of social contact and paternal behavior. In the first study, the axon-sparing excitotoxin N-methyl-D,L-aspartic acid (NMA) produced lesions in the basolateral nucleus of the amygdala or the corticomedial amygdala. Males with corticomedial lesions showed significantly less contact with a familiar adult female and a pup when compared with males with lesions of the basolateral nucleus or controls. This behavioral change was not associated with changes in exploratory behavior, motor function, performance in an olfactory task, fearfulness, physical well-being, or body temperature. In a second study, NMA lesions restricted to the medial nucleus also decreased paternal behavior. Neurons in the medial nucleus of the amygdala appear to be essential for the normal expression of paternal care in this species.

Amygdala↗
PubMed1994

The pharmacokinetics of once daily gentamicin in neutropenic adults with haematological malignancy.

Seven febrile neutropenic adults with normal renal function were treated with intravenous gentamicin 4.5 mg/kg once a day in combination with azlocillin. Gentamicin serum concentrations 1, 2, 4, 8, and 24 h after a 30 min infusion were 10.9 +/- 0.6, 7.1 +/- 0.4, 4.2 +/- 0.2, 1.8 +/- 0.1 and 0.16 +/- 0.003 mg/L respectively. The pharmacokinetics were best described by a triphasic plot including a distribution phase (about 1/2 h) and two elimination phases, an early and late.

Adolescent↗
PubMed1994

Depressive symptoms and the deficit syndrome of schizophrenia.

One of the most influential ideas in schizophrenia research is that schizophrenia may be a syndrome with significant pathophysiological heterogeneity, rather than a single disease. Among patients with schizophrenia, presence or absence of the deficit syndrome has been suggested as a method for defining relatively homogeneous groups. The criteria for the deficit syndrome require the presence of negative symptoms that are judged primary to the illness, rather than to factors, such as depressive mood, that may resemble the negative symptoms of schizophrenia. To test one aspect of the validity of the primary/secondary judgment, we tested the relationship of depressive symptoms to the deficit/nondeficit categorization. Using independent clinician ratings, the depressive mood of deficit and nondeficit patients was compared at the time the categorization was made, and at an average follow-up of 2 1/2 years. Using patients' self ratings, deficit and nondeficit patients were compared at an average follow-up of 1 1/2 years. Deficit patients had significantly less severe depressive symptoms by clinicians' ratings both cross-sectionally and at follow-up, and less severe self-rated symptoms at follow-up. These differences were not due to confounding by age, race, sex, socioeconomic status, or chronicity. These results support the validity of the deficit/nondeficit categorization.

Adult↗
PubMed1994

Effects of clozapine on positive and negative symptoms in outpatients with schizophrenia.

OBJECTIVE: Clozapine is an atypical neuroleptic with superior efficacy in severely ill, treatment-resistant inpatients with schizophrenia. To determine if clozapine's differential efficacy generalizes to less ill, outpatients populations, the authors examined the effects of clozapine on positive and negative symptoms in outpatients with schizophrenia. METHOD: Outpatients with schizophrenia who had histories of partial response to conventional neuroleptics and who had not responded to a prospective 6-week trial of fluphenazine participated in a 10-week, double-blind, parallel-groups comparison of clozapine and haloperidol. Thirteen men and six women were given clozapine, and 15 men and five women were given haloperidol. Clinical response rates were determined and effects on primary versus secondary negative symptoms were addressed. Doses of clozapine and haloperidol at the end of the 10-week trial were 410.5 mg/day (SD = 45.8) and 24.8 mg/day (SD = 5.5), respectively. RESULTS: Clozapine was superior to haloperidol for treating positive symptoms. In addition, eight of the patients given clozapine and only one of the patients given haloperidol fulfilled clinical responder criteria. Clozapine was also superior to haloperidol for treating negative symptoms, although these effects were relatively minor. Negative symptoms were significantly affected in the subgroup of patients with nondeficit schizophrenia but not in the subgroup with deficit schizophrenia. Overall, clozapine was well tolerated. CONCLUSIONS: Clozapine has superior efficacy for treating positive symptoms in partially responsive outpatients with chronic schizophrenia, suggesting that it has utility for a broad spectrum of patients with schizophrenia beyond the most severely ill.

Adult↗
PubMed1993

Strong inference, theory testing, and the neuroanatomy of schizophrenia.

Failure to address the putative etiologic and pathophysiologic heterogeneity of the schizophrenia syndrome and problems in definitive assessment of human brain function have impaired progress in schizophrenia research. New approaches to psychopathology and converging evidence from antemortem and postmortem study can now result in more decisive study of the neuroanatomy and neuropathology of schizophrenia.

Brain↗
PubMed1993

Characterization of an insertion sequence (IS53) located within IS51 on the iaa-containing plasmid of Pseudomonas syringae pv. savastanoi.

A 2568-base pair (bp) insertion sequence (IS53) was cloned from the iaa-containing plasmid pIAA2 of Pseudomonas syringae subsp. savastanoi. IS53 is located downstream from the iaa operon and is inserted into IS51, a previously described element on pIAA2. IS53 causes an 8-bp target duplication and has nearly perfect terminal inverted repeats of 27 bp. Several degenerate copies of the inverted repeats are located internal, and in direct orientation to the terminal inverted repeats. A putative transposase gene conforms to the transposase ORF/opposite strand overlapping ORF motif described in many gram-negative IS elements. The region 5' to the presumptive transposase gene contains sequences that are homologous to the consensus E. coli heat-shock (sigma 32) promoter.

Amino Acid Sequence↗
PubMed1993

Case identification and stability of the deficit syndrome of schizophrenia.

In certain situations, such as large epidemiological studies, it may be necessary to use proxy case-identification tools instead of "gold-standard" assessments. The deficit syndrome of schizophrenia requires a clinical assessment that may not be feasible in some study populations. Measures for the discrimination of deficit and nondeficit patients, based on the Brief Psychiatric Rating Scale (BPRS), were assessed in a group of 100 outpatients with chronic schizophrenia. A rationally based case-identification tool was validated, and its case-identification properties were found to be stable over time; consequently, this proxy measure may be of use in other data sets. The stability of the relationship between this BPRS measure and the deficit/nondeficit categorization supports the view that it is a valid categorization.

Adult↗
PubMed1993

Structural abnormalities in deficit and nondeficit schizophrenia.

OBJECTIVE: Previous studies have suggested the involvement of the frontal and parietal cortices and thalamus in a neural circuit underlying the production of primary enduring negative or deficit symptoms of schizophrenia. The purpose of this study was to examine whether structural changes in the proposed circuit are associated with the production of deficit symptoms. METHOD: Magnetic resonance imaging was used to measure the volume of selected circuit brain regions (i.e., the prefrontal region and caudate) and noncircuit brain regions (i.e., the amygdala/hippocampus complex) in 17 deficit and 24 nondeficit schizophrenic outpatients and 30 normal comparison subjects. RESULTS: Right and left total prefrontal volumes discriminated deficit from nondeficit patients, with prefrontal volumes being smaller in nondeficit patients. There were no differences between the two schizophrenic subgroups in left caudate or right and left amygdala/hippocampus complex volumes. The right caudate was larger in deficit patients, but the difference between the two schizophrenic subgroups was not significant. There were no differences between deficit and normal subjects on any prefrontal region measure. Nondeficit patients had smaller total right and left prefrontal volumes than normal subjects. Both schizophrenic subgroups had larger left caudate volumes and smaller right and left amygdala/hippocampus complex volumes than the normal subjects. There was a trend for deficit patients to have larger right caudate volumes. CONCLUSIONS: These results suggest that structural changes in the prefrontal region are not responsible for deficit symptoms. The caudate, particularly the right caudate, may be associated with the production of these symptoms.

Frontal Lobe↗
PubMed1993

Patient survival on PAN/AN69 membrane hemodialysis: a ten-year analysis.

Survival characteristics over a 10-yr period of 352 patients on hemodialysis (HD) with polyacrylonitrile membranes in a single center were retrospectively analyzed and compared with national data collected by the U.S. Renal Data System (USRDS). Only those patients who stayed on HD for longer than 3 months were included. Any outcome other than death was considered as lost to follow-up. The number of expected deaths in the entire patient population according to the USRDS data base was 203, whereas the observed actual rate was only 132, reaching high statistical significance. Several subgroups of patients, stratified on the basis of age and time on starting HD, diabetes mellitus as the cause of original renal disease, etc., also exhibited significantly better survival. HD with a biocompatible membrane, providing adequate removal of low- as well as "middle"-molecular-weight uremic toxins, may be one important explanation for improved survival.

Acrylic Resins↗
PubMed1993

Patient survival on PAN/AN69 membrane hemodialysis: a ten year analysis.

Survival characteristics over a 10 year period of 340 patients on hemodialysis (HD), using PAN/AN69 membrane, were retrospectively analyzed and compared with national data collected by the U.S. Renal Data System (USRDS). Only those patients who stayed on HD longer than three months were included. Any outcome other than death was considered as lost to follow-up. The number of expected deaths in the entire patient population according to USRDS database was 190, whereas the observed actual rate was only 120, a highly statistically significant difference. Several subgroups of patients also exhibited significant improvement in survival. Adequate HD with a biocompatible membrane is offered as one important explanation for improved patient survival.

Adolescent↗
PubMed1992

Plasma prolactin as a predictor of relapse in drug-free schizophrenic outpatients.

A low plasma prolactin concentration has been reported to be associated with an increased risk of subsequent relapse in patients with schizophrenia. Prolactin concentration was measured in samples from stable schizophrenic men who were outpatients just prior to neuroleptic withdrawal. No relationship between prolactin concentration and time to subsequent relapse was found. Prolactin concentration may predict time to relapse only in populations characterized by specific demographic features or medication history.

Administration, Oral↗
PubMed1992

Clinical predictors of relapse following neuroleptic withdrawal.

The validity of previously hypothesized predictors of elapse following neuroleptic discontinuation was examined. One hundred sixty-two outpatients, with either Research Diagnostic Criteria schizophrenia or schizoaffective disorder, were discontinued from neuroleptic medication for a 28-day period or until judged to be relapsed. Pre-discontinuation neuroleptic dosage level, the severity of psychotic symptoms, and the presence of dyskinetic movements prior to neuroleptic discontinuation were the predictor variables. Of the 162 patients, 62.7% did not relapse during the study period. There were no differences in the survival rates between the patients withdrawn from oral versus depot neuroleptics. Neuroleptic dosage, but not severity of psychotic symptoms or dyskinetic movements, predicted relapse. These results support the hypothesis that pre-withdrawal neuroleptic dosage level predicts relapse, but fail to validate either severity of psychotic symptoms or presence of dyskinetic movements as predictors of relapse.

Administration, Oral↗
PubMed1992

Limbic system abnormalities identified in schizophrenia using positron emission tomography with fluorodeoxyglucose and neocortical alterations with deficit syndrome.

A hypothesis of psychosis localization in schizophrenia was derived from studying metabolic alterations in rat brain in response to phencyclidine hydrochloride administration. Since phencyclidine and its selective agonist dizocilpine maleate (MK801) induced overlapping and long-lasting metabolic alterations predominantly in limbic areas, the hypothesis developed that schizophrenic patients with psychosis would evidence functional abnormalities in limbic circuits compared with normal controls. Accordingly, 12 actively psychotic, drug-free patients with schizophrenia and matched normal controls underwent functional brain scans using positron emission tomography and fluorodeoxyglucose. Regions of interest were identified on five matched axial slices in each patient and control subject, and average metabolic rates were calculated. Patients with schizophrenia showed a significantly lower regional cerebral metabolic rate of glucose in the hippocampus and the anterior cingulate cortex than did normal controls, but not in neocortical areas or in the extrapyramidal system. When the group of schizophrenic patients was divided into deficit and nondeficit types, a preliminary exploratory analysis suggested thalamic, frontal, and parietal cortical hypometabolism in the deficit subgroup, with normal metabolism in the nondeficit patient group in those areas; in contrast, hippocampal and anterior cingulate cortical metabolism was reduced in both deficit and nondeficit subtypes. These results suggest that the limbic system, especially the hippocampus, is functionally involved in schizophrenic psychosis and that different manifestations of schizophrenia may involve different neuronal circuits.

Adolescent↗