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B Kirkpatrick

Publications and source records attributed to B Kirkpatrick.

At least 19 recordsLinked to original sources
PubMed2004

Mapping of bovine ovulation rate QTL; an analytical approach for three generation pedigrees.

Interval mapping was conducted for ovulation rate quantitative trait loci (QTL) using data from two related families from the United States Department of Agriculture, US Meat Animal Research Center twinning cattle herd. Both families are extended, three generation pedigrees from which records of sons, daughters and granddaughters were analysed. Both a method of analysis and results from that analysis are reported herein. Results from one of the two families (839802) were previously reported, but reanalysis here including the second, related family (839803) and a revised statistical model lessens support for the previously reported QTL. Results from interval mapping provided evidence for QTL in regions corresponding to those previously suggested for chromosomes 7 (chromosome-wise P < 0.05) and 19 (chromosome-wise P < 0.01) in the 839802 family, although statistical significance was reduced. In contrast to the previous report, evidence for a chromosome 5 QTL in the same family was greatly reduced while support for a QTL on chromosome 10 increased (chromosome-wise P < 0.01). Analysis of data from the related 839803 family failed to replicate evidence of QTL observed on either chromosome 7 or chromosome 19 in the 839802 family.

Agriculture↗
PubMed2001

A five-year followup study of deficit and nondeficit schizophrenia.

Previous studies have suggested that deficit schizophrenia is a stable subtype of schizophrenia, and that patients with the deficit schizophrenia have different course of illness from other people with schizophrenia. We tested the ability of the deficit/nondeficit categorization to predict clinical features at five years' followup in a group of chronically ill outpatients. Outpatients categorized into deficit (N = 46) and nondeficit (N = 174) schizophrenia were assessed at an average of five years after the categorization was made. Raters making the followup assessments were blind to the initial categorization. At followup, the deficit patients had poorer quality of life, poorer social and occupational function, and more severe negative symptoms. Despite these differences, deficit patients were less distressed (as measured by depressive mood, anxiety, and guilt), and they did not have more severe hallucinations, delusions, thought disorder. These differences could not be attributed to demographic differences. The group differences in quality of life and level of psychosocial function remained significant after accounting for the severity of baseline negative symptoms. These findings confirm that patients with the deficit schizophrenia have a set of relatively stable clinical features that are associated with poor outcome.

Adult↗
PubMed2001

Schizophrenia and season of birth in a tropical region: relationship to rainfall.

Winter birth has been shown to increase the risk of schizophrenia in adult life. It has been hypothesized that this effect is due to seasonal variation in infectious diseases, including influenza, as exposure to influenza during mid gestation also increases the risk of schizophrenia. However, in many areas there is little variation in temperature during the year, although rainfall may vary greatly. We tested the hypothesis that, in a tropical region with wet and dry seasons, schizophrenia births would be related to rainfall. The data came from the city of Mossoro in north-eastern Brazil. In this area there is no meaningful variation in temperature, but there is a rainy season with little precipitation during the rest of the year. In this region, the prevalence of influenza parallels that of rainfall. There was a significant relationship between rainfall and the number of schizophrenia births three months later. In contrast, there was no significant relationship between rainfall and general population births three months later. The relationship of birth to rainfall, rather than winter birth, may be associated with risk of schizophrenia in tropical regions; exposure to influenza during gestation may be the basis for such a relationship.

Adult↗
PubMed2001

Suspiciousness as a specific risk factor for major depressive episodes in schizophrenia.

OBJECTIVE: Serious depression is a common and important complication of schizophrenia. In a prospective, population-based study, we tested the hypothesis that suspiciousness increases the risk for the later development of depression in schizophrenia. METHOD: Data came from the Epidemiological Catchment Area (ECA) study. Baseline clinical and demographic features were used to predict the onset of new episodes of depression at 1 year follow-up. As ECA diagnoses were based on lay interviews, which may have low sensitivity compared with clinical diagnoses, two overlapping groups of putative schizophrenia patients were defined. RESULTS: Suspiciousness was associated with an increased risk of new episodes of depression in both patient groups, after accounting for demographic variables. There was no association between an increased risk of depression and either disorganization or hallucinations and delusions. CONCLUSIONS: Suspiciousness appears to be a specific risk factor for depression in psychotic groups. Interventions that decrease suspiciousness, or mitigate its isolating effects, might decrease the risk of serious depression and suicide.

Adult↗
PubMed2001

A separate disease within the syndrome of schizophrenia.

If schizophrenia is a clinical syndrome rather than a single disease, the identification of specific diseases within the syndrome would facilitate the advance of knowledge and the development of more specific treatments. We propose that deficit psychopathology (ie, enduring, idiopathic negative symptoms) defines a group of patients with a disease different from schizophrenia without deficit features, as the deficit and nondeficit groups differ in their signs and symptoms, course, biological correlates, treatment response, and etiologic factors. These differences cannot be attributed to more severe positive psychotic symptoms or a greater duration of illness in the deficit group. The alternative interpretation that patients with deficit schizophrenia are at the severe end of a single disease continuum is not supported by risk factor and biological features data, but there is a need for independent replication of these findings. We suggest a series of studies designed to falsify one of these hypotheses, ie, multiple diseases vs a single disease.

Antibodies, Viral↗
PubMed2001

Subclinical suspiciousness as a risk factor for depressive episodes.

OBJECTIVE: Previous studies suggest suspiciousness is associated with an increased risk of major depressive episodes in psychotic patients. We tested the hypothesis that this relationship would extend to nonpsychotic groups. METHOD: Data came from the Epidemiological Catchment Area (ECA) study, a longitudinal population-based study conducted at five sites in the United States. Baseline clinical and demographic features were used to predict the onset of episodes of depression at 1-year follow-up in subjects without psychotic symptoms. RESULTS: Subclinical suspiciousness was associated with an increased risk of new episodes of depression after accounting for demographic variables. However, three of six subclinical delusion-like experiences were also associated with an increased risk of depressive episodes. None of the subclinical hallucination-like experiences predicted subsequent risk. CONCLUSION: Subclinical suspiciousness appears to increase the risk of depression in the general population. Some other delusion-like experiences may do the same.

Delusions↗
PubMed2001

At issue: stress, hippocampal neuronal turnover, and neuropsychiatric disorders.

Stress-induced changes in the glucocorticoid system may be toxic for hippocampal cells in animals. Recently, neurogenesis has been shown in the rat, the primate, and the human hippocampus. Because chronic stress is associated with some neuropsychiatric disorders, including schizophrenia, it is possible that an imbalance in the normal turnover of hippocampal cells plays a role in the pathophysiology not only of schizophrenia but also of other neuropsychiatric disorders that involve high levels of stress. New therapeutic possibilities arise if such a process is proven to occur.

Hippocampus↗
PubMed2001

Summer birth and deficit schizophrenia in the epidemiological catchment area study.

Winter birth is a widely replicated risk factor for schizophrenia. However, previous studies have suggested that patients with the deficit syndrome of schizophrenia have an excess of summer births. We tested the summer birth effect in a population-based study. Data came from the Epidemiological Catchment Area study, which had a representative sample of the U.S. population. Psychotic patients with features of the deficit syndrome had a significant association with summer birth, compared with the general population. There was also a significant association between summer birth and the deficit syndrome within the psychotic population, after accounting for the variance due to disorganization, hallucinations and delusions, and demographic characteristics. These findings add to the evidence suggesting the etiopathophysiology of the deficit group differs from that found in other patients with schizophrenia.

Adult↗
PubMed2001

Summer birth and deficit schizophrenia in Nithsdale, Scotland.

Patients with deficit schizophrenia differ from other people with schizophrenia relative to course of illness, treatment response, and neurobiological correlates. An association between deficit schizophrenia and summer birth, in contrast to the winter birth risk factor associated with schizophrenia as a whole, has also been reported. We attempted to replicate the association between summer birth and deficit schizophrenia by using data from a prevalence survey in Nithsdale in southwest Scotland, in which all patients with schizophrenia in Nithsdale were identified and 87% were interviewed directly. Deficit schizophrenia was associated with summer birth, defined as birth in June/July/August (p < .02), June/July (p < .02), or July/August (p < .03). The association with summer birth is consistent with other evidence that patients with deficit schizophrenia have a pathophysiology that differs in some ways from that of other patients with schizophrenia.

Female↗
PubMed2001

Genetic diversity of Pierce's disease strains and other pathotypes of Xylella fastidiosa.

Strains of Xylella fastidiosa isolated from grape, almond, maple, and oleander were characterized by enterobacterial repetitive intergenic consensus sequence-, repetitive extragenic palindromic element (REP)-, and random amplified polymorphic DNA (RAPD)-PCR; contour-clamped homogeneous electric field (CHEF) gel electrophoresis; plasmid content; and sequencing of the 16S-23S rRNA spacer region. Combining methods gave greater resolution of strain groupings than any single method. Strains isolated from grape with Pierce's disease (PD) from California, Florida, and Georgia showed greater than previously reported genetic variability, including plasmid contents, but formed a cluster based on analysis of RAPD-PCR products, NotI and SpeI genomic DNA fingerprints, and 16S-23S rRNA spacer region sequence. Two groupings of almond leaf scorch (ALS) strains were distinguished by RAPD-PCR and CHEF gel electrophoresis, but some ALS isolates were clustered within the PD group. RAPD-PCR, CHEF gel electrophoresis, and 16S-23S rRNA sequence analysis produced the same groupings of strains, with RAPD-PCR resolving the greatest genetic differences. Oleander strains, phony peach disease (PP), and oak leaf scorch (OLS) strains were distinct from other strains. DNA profiles constructed by REP-PCR analysis were the same or very similar among all grape strains and most almond strains but different among some almond strains and all other strains tested. Eight of 12 ALS strains and 4 of 14 PD strains of X. fastidiosa isolated in California contained plasmids. All oleander strains carried the same-sized plasmid; all OLS strains carried the same-sized plasmid. A plum leaf scald strain contained three plasmids, two of which were the same sizes as those found in PP strains. These findings support a division of X. fastidiosa at the subspecies or pathovar level.

Bacterial Typing Techniques↗
PubMed2000

Family characteristics of deficit and nondeficit schizophrenia in the Roscommon Family Study.

Studies of course, treatment response, biological correlates, and environmental risk factors have suggested that the deficit syndrome of schizophrenia defines a meaningful subgroup within schizophrenia. Probands from the Roscommon Family Study who met criteria for schizophrenia or simple schizophrenia were categorized into deficit (N=22) and nondeficit (N=111). Within schizophrenia, the lifetime prevalence of the deficit syndrome was 16.5%; the percentage of males was 91% compared to 63% in the nondeficit group. The first-degree relatives of deficit probands had a significantly greater social isolation than the relatives of nondeficit probands, despite significantly less severe dysphoria and psychotic-like symptoms. The risk of schizophrenia was 1.75 times greater in the families of deficit compared to nondeficit probands. There were no significant differences in the adjusted morbid risk for nonaffective psychosis, affective disorder, or alcoholism. These results provide further evidence that the deficit syndrome is a marker of a group of patients with clinical and neurobiological characteristics that distinguish them from the rest of schizophrenia. The deficit syndrome may be a useful phenotype in genetic linkage studies.

Female↗
PubMed2000

Mazindol treatment of negative symptoms.

Hypodopaminergic and hyponoradrenergic pathophysiology may be a basis for primary and/or secondary negative symptoms in schizophrenia. The hypothesis that enhanced neurotransmission in these systems would be therapeutic for negative symptoms was tested by comparing mazindol and placebo in a double-blind, cross-over design trial. Outcome following mazindol supplementation was comparable to placebo supplementation (F(1,30) = 0.9; p = .57). Results for deficit and non-deficit schizophrenia subjects were similar, and were not affected by whether concurrent the antipsychotic drug treatment was clozapine, fluphenazine, or haloperidol. The efficacy hypothesis was not supported for either primary or secondary negative symptoms.

Adult↗
PubMed2000

Assessing the efficacy of treatments for the deficit syndrome of schizophrenia.

The primary, enduring negative symptoms found in some patients with schizophrenia have become the focus of clinical treatment trials, but there has been no consensus on the best methods for approaching this area. In future trials, a number of issues need to be considered, including analytic strategies, the limitations in instruments used to measure negative symptoms, and study design. An appropriate design for establishing the efficacy of treatments for the deficit syndrome is proposed.

Clinical Trials as Topic↗
PubMed2000

At issue: a default analysis for schizophrenia research.

The concept that there are at least three clinical syndromes within schizophrenia has been influential, and the significance of these syndromes is supported by a growing number of studies. However, the meaning of these syndromes is not clear. The yield of research studies could be increased by the application of a "default" data analysis, in which the differential association--if any--of the three syndromes with the dependent variable(s) of a study is determined.

Diagnosis, Differential↗
PubMed2000

Risk factors for the deficit syndrome of schizophrenia.

Previous studies have found two risk factors associated with the deficit syndrome of schizophrenia: an increase in summer births, compared to others with schizophrenia; and a higher risk of schizophrenia in relatives. In data from the Camberwell Register Psychosis Series, a population-based sample that approximated a treated-incidence sample, the deficit/nondeficit categorization was made using a previously validated proxy method. Associations were found between the deficit syndrome and both summer birth and a family history of schizophrenia. In contrast, nondeficit schizophrenia was associated with a family history of psychiatric problems other than schizophrenia. The deficit group also had poorer insight. An early age of onset was associated with disorganization, but not with the deficit or nondeficit group. The deficit/nondeficit differences could not be attributed to confounding by demographic features or the severity of hallucinations, delusions, or formal thought disorder.

Age of Onset↗