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J Stewart

Publications and source records attributed to J Stewart.

At least 73 records · Page 4Linked to original sources
PubMed2001

4-Hydroxynonenal immunoreactivity is increased in human hippocampus after global ischemia.

Oxidative stress and lipid peroxidation may contribute to the pathology of neurodegenerative disorders such as Alzheimer's disease (AD) and cerebral ischemia. 4-Hydroxynonenal (4-HNE) is a toxic by-product of lipid peroxidation, and immunoreactivity to 4-HNE has been used to examine lipid peroxidation in the pathogenesis of AD and ischemia. This study sought to determine 1) if there are cellular alterations in 4-HNE immunoreactivity in the human hippocampus after global ischemia, and 2) whether possession of an apolipoprotein E (APOE) epsilon4 allele influenced the extent of 4-HNE immunoreactivity. 4-HNE immunoreactivity was assessed semi-quantitatively in the temporal lobe of a group of controls (n = 44) and in a group of patients who had an episode of global ischemia as a result of a cardiorespiratory arrest and subsequently died (n = 56, survival ranged from 1hr to 42 days). There was minimal cellular 4-HNE immunoreactivity in the control group. However, compared to controls, 4-HNE immunoreactivity was significantly increased in neurons (p < 0.0002) and glia (p < 0.0001) in the hippocampal formation after global ischemia. Possession of an APOE epsilon4 allele did not influence the extent of neuronal or glial 4-HNE immunostaining in the control or global ischemia group. There was a significant negative correlation between the extent of neuronal 4-HNE immunoreactivity with survival period after global ischemia (r2 = 0.0801; p < 0.036) and a significant positive correlation between the extent of glial 4-HNE immunoreactivity and survival after global ischemia (r2 = 0.2958; p < 0.0001). The data indicate a marked increase in neuronal and glial 4-HNE. This substantiates a role for lipid peroxidation in the pathogenesis of cerebral ischemia. There was no indication that APOE genotype influenced the extent of 4-HNE immunoreactivity.

Adolescent↗
PubMed2001

Amplification of mutator cells in a population as a result of horizontal transfer.

Mutator cells that lack the mismatch repair system (MMR(-)) occur at rates of 10(-5) or less in laboratory populations started from wild-type cells. We show that after selection for recombinants in an interspecies mating between Salmonella enterica serovar Typhimurium and Escherichia coli, the percentage of MMR(-) cells rises to several percent of the recombinant population, and after a second successive mating and selection, greater than 95% of the recombinants are MMR(-). Coupling a single cross and selection with either mutagenesis or selection for spontaneous mutants also results in a dramatic increase in MMR(-) cells. We discuss how horizontal transfer can result in mutator strains during adaptive evolution.

Base Pair Mismatch↗
PubMed2001

Estimates of the prevalence of acute stroke impairments and disability in a multiethnic population.

BACKGROUND AND PURPOSE: The goals of the present study were to estimate the prevalence of acute impairments and disability in a multiethnic population of first-ever stroke and to identify differences in impairment and early disability between pathological and Bamford subtypes. Associations between impairments and death and disability at 3 months were identified. METHODS: Impairments that occur at the time of maximum neurological deficit were recorded, and disability according to the Barthel Index (BI) was assessed 1 week and 3 months after stroke in patients in the South London Stroke Register: RESULTS: Of 1259 registered patients, 6% had 1 or 2, 31.1% had 3 to 5, 50.6% had 6 to 10, and 10.6% had >10 impairments. Common impairments were weakness (upper limb, 77.4%), urinary incontinence (48.2%), impaired consciousness (44.7%), dysphagia (44.7%), and impaired cognition (43.9%). Patients with total anterior circulation infarcts had the highest age-adjusted prevalence of weakness, dysphagia, urinary incontinence, cognitive impairment, and disability. Patients with subarachnoid hemorrhage had the highest rates of coma. Patients with lacunar stroke had the high prevalence of weakness but were least affected by disability, incontinence, and cognitive dysfunction. Blacks had higher age- and sex-adjusted rates of disability in ischemic stroke (BI <20, odds ratio 2.76, 95% CI 1.47 to 5.21, P=0.002; BI <15, odds ratio 1.8, 95% CI 1.45 to 2.81, P=0.01) but impairment rates similar to those of whites. On multivariable analysis, incontinence, coma, dysphagia, cognitive impairment, and gaze paresis were independently associated with severe disability (BI <10) and death at 3 months. CONCLUSIONS: The extent of these findings indicates that an acute assessment of impairments and disability is necessary to determine the appropriate nursing and rehabilitation needs of patients with stroke.

Age Distribution↗
PubMed2001

A randomized comparison of low-dose ketamine and lignocaine infiltration with ketamine-diazepam anaesthesia for post partum tubal ligation in Vanuatu.

Ketamine remains one of the most commonly used anaesthetic agents around the world. Despite it being the anaesthetic agent of choice in many developing nations, there is a paucity of literature describing ketamine in the developing world. In what we believe is the first randomized controlled trial to be performed in Vanuatu (formerly the New Hebrides) we compared the use of ketamine 0.9 mg/kg and diazepam 0.07 mg/kg with ketamine 0.3 mg/kg and 2% lignocaine infiltration in 50 Melanesian women undergoing post partum tubal ligation. All women received 0.5 mg/kg intramuscular pethidine. Visual analog pain scores and verbal numeric satisfaction scores were similar between the groups. However the time to obeyed command was significantly faster in the 0.3 mg/kg ketamine group (7.0+/-4.9 vs 13.0+/-9.2 min). The incidence of dreaming was similar and the content rated as pleasant by both groups. In institutions where post-anaesthesia care resources are limited, 0.3 mg/kg ketamine with local anaesthesia provides for earlier self-care of patients after tubal ligation, without compromise of analgesia, emergence or satisfaction. The implications of these findings extend to other procedures that require short general anaesthesia, which can be adequately performed with low-dose ketamine and local anaesthesia. The latter technique allows more rapid awakening.

Adult↗
PubMed2001

Home safety.

There are more accidents in the home than many other environments, yet there is no duty on local authorities to promote domestic safety per se and the discretionary powers under the Home Safety Act 1961 are rarely used. The local authority remit in safe housing is therefore largely through housing enforcement and grant led activity. The main statutory controls available to local authorities in addressing home safety are found under various Housing Acts, in particular the statutory standard of fitness for habitation, which can provide remedy for some, although not all, potential home accidents. There are many potential hazards in the home which current legislation fails to address. This is one reason why a new standard of assessing domestic conditions--the Housing Health and Safety Rating System--is currently being considered. This new system seeks to change the current emphasis on a 'materials and construction specification' type approach to a system based on known domestic hazards and their reduction ('performance specification') although there remains much debate around the subject. This paper considers the current and proposed systems and other opportunities available to local authorities in addressing the major area of home safety.

Accidents, Home↗
PubMed2001

MCF-10A-NeoST: a new cell system for studying cell-ECM and cell-cell interactions in breast cancer.

PURPOSE: There is a continuing need for genetically matched cell systems to model cellular behaviors that are frequently observed in aggressive breast cancers. EXPERIMENTAL DESIGN: We report here the isolation and initial characterization of a spontaneously arising variant of MCF-10A cells, NeoST, which provides a new model to study cell adhesion and signal transduction in breast cancer. RESULTS: NeoST cells recapitulate important biological and biochemical features of metastatic breast cancer, including anchorage-independent growth, invasiveness in three-dimensional reconstituted membranes, loss of E-cadherin expression, and increased tyrosine kinase activity. A comprehensive analysis of tyrosine kinase expression revealed overexpression or functional activation of the Axl, FAK, and EphA2 tyrosine kinases in transformed MCF-10A cells. CONCLUSIONS: MCF-10A and these new derivatives provide a genetically matched model to study defects in cell adhesion and signaling that are relevant to cellular behaviors that often typify aggressive breast cancer cells.

Breast Neoplasms↗
PubMed2000

No evidence for a parent-of-origin effect detected in the pattern of inheritance of schizophrenia.

BACKGROUND: Schizophrenia is a complex genetic disorder with no clear pattern of inheritance. Epigenetic modification of genes may thus play a role in its transmission. METHODS: In our study, 439 families with at least two ill siblings with schizophrenia (208 with unilineal transmission) were examined for evidence of a parent-of-origin effect (e.g., evidence of parental imprinting on the familial transmission of schizophrenia). RESULTS: No significant difference in the prevalence of maternal compared with paternal transmission was found. In addition, affected male subjects did not differ from affected female subjects in the proportion of their offspring diagnosed with schizophrenia. CONCLUSIONS: Although the transmission of schizophrenia may be influenced by epigenetic events, our study fails to find evidence that one epigenetic mechanism, a parent-of-origin imprinting effect, determines whether an individual expresses the illness.

Adult↗
PubMed2000

Failure to establish linkage on the X chromosome in 301 families with schizophrenia or schizoaffective disorder.

The hypothesis that a gene for susceptibility to psychosis (specifically in the X-Y homologous class) is located on the sex chromosomes has been proposed. Such a gene would account for the excess of sex chromosome anomalous males and females in populations of patients with psychosis, a tendency towards concordance by sex within families, and sex differences associated with psychosis and its underlying brain pathology. In earlier studies we observed small positive LOD scores in Xp11, and in a more recent and larger cohort of 178 sibling pairs, a peak multipoint nonparametric LOD score of 1. 55 at the locus DXS8032 in Xq21. The present study with a new set of markers extended the cohort to 301 ill sibling pairs and their parents. Despite the increase in sample size, the LOD score did not increase. A peak NPL of 1.55 was observed at the locus DXS1068 in proximal Xp, a region remote from the previous report. Separating families into those who were more likely to have X chromosome inheritance (maternal with no male to male transmission) did not yield stronger findings. In spite of the evidence that psychosis is related to a sex-dependent dimension of cerebral asymmetry, it is concluded that no consistent linkage of schizophrenia to the X chromosome can be demonstrated. In the context of the general failure of replication of linkage in psychosis, the possibility that the genetic predisposition to psychosis is contributed to by epigenetic modification rather than variations in the nucleotide sequence has to be considered.

Chromosome Mapping↗
PubMed2000

Investigation of a candidate gene for schizophrenia on Xq13 previously associated with mental retardation and hypothyroidism.

Weak support for linkage of schizophrenia to proximal Xq has previously been reported. In addition, an increased prevalence of thyroid disorder has been noted in families of individuals with schizophrenia. Recently, a gene mapped to Xq13 termed HOPA has been found to be associated with mental retardation, hypothyroidism, and depression and to function as a coactivator for the thyroid receptor. We therefore examined the HOPA gene in a group of 111 probands from a larger cohort of multiplex families with schizophrenia, several of whom (n = 53) also had a family history of hypothyroidism. Four males and two females were found with an alteration in exon 42 of the HOPA gene compared with 8/492 males and 18/471 females (942 X chromosomes) compared with consecutively screened newborns (chi(2) = 3.92, P < 0.05). However, when available family members of each of the probands with an exon 42 variation were subsequently screened, the mutation did not segregate with schizophrenia in three of five families, although all 6 probands with an exon 42 variation did have hypothyroidism in either themselves (n = 3) or their mothers (n = 3) (P < 0.008). These findings replicate prior findings demonstrating an association between HOPA polymorphisms and hypothyroidism. In addition, the increased frequency of HOPA variants in this population may also provide a genetic basis for the familial association of thyroid disease and schizophrenia.

Amino Acid Sequence↗
PubMed2000

Pharmacokinetics of three formulations of ondansetron hydrochloride in healthy volunteers: 24-mg oral tablet, rectal suppository, and i.v. infusion.

The absolute bioavailability and pharmacokinetics of three formulations of ondansetron hydrochloride 24 mg--an oral tablet, an intravenous solution, and an extemporaneous rectal suppository--were studied. Twelve healthy, nonsmoking volunteers (six men and six women) were given ondansetron in a study with a three-way cross-over design. All subjects received each dosage form on the same day in the following order: oral tablet, rectal suppository, and intravenous infusion. Administrations were separated by one week. Blood sampling times varied, depending on the administration route. Mean absolute bioavailability for the oral tablet and the rectal suppository differed significantly. Absorption of ondansetron was prolonged when it was administered as the rectal suppository. Absolute bioavailability for the 24-mg tablet was similar to that for other tablet strengths in previous studies. All subjects completed the study without significant adverse effects. Absorption of ondansetron from the rectal suppository was prolonged compared with the oral tablet and the i.v. infusion. Bioavailability for the 24-mg suppository formulation was considerably lower than for the 24-mg tablet.

Antiemetics↗
PubMed2000

Amyloid beta-protein length and cerebral amyloid angiopathy-related haemorrhage.

The relationship between amyloid beta-protein (A beta) length and the apolipoprotein E (APOE) epsilon 2 allele, which is over-represented in cerebral amyloid angiopathy-related haemorrhage (CAAH), has not previously been examined. Of 57 CAA patients studied, 37 had CAAH. All patients, particularly those with CAAH had more blood vessels immunoreactive for A beta 40 than A beta 42 in both the leptomeninges and cerebral cortex. CAAH patients had more A beta 40-immunoreactive blood vessels in the leptomeninges (p < 0.001) and cortex (p = 0.027) than had non-haemorrhage patients. Cortical blood vessels, the usual source of haemorrhage in CAAH, were more frequently A beta 42 immunoreactive in APOE epsilon 2 carriers than in non-epsilon 2 carriers (p = 0.022). The APOE epsilon 2 allele may predispose to CAAH by increasing the seeding of cortical blood vessels by A beta 42.

Aged↗
PubMed2000

Lack of evidence for linkage to chromosomes 13 and 8 for schizophrenia and schizoaffective disorder.

A previous report [Blouin et al., 1998: Nat Genet 20:70-73] suggesting linkage to chromosomes 13q32 and 8p21 in families with schizophrenia led us to investigate these regions in a large set of 301 multiplex families with schizophrenia. Multipoint analyses failed to reveal evidence for linkage to any portion of chromosome 13, while only a weakly positive score was present on 8p using the identical marker reported in the earlier report. Failure to confirm the Blouin et al claims in a substantially larger cohort adds emphasis to the inconsistency of the findings concerning linkage in schizophrenia. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:235-239, 2000.

Chromosomes, Human, Pair 13↗
PubMed2000

Requirement of endogenous basic fibroblast growth factor for sensitization to amphetamine.

Repeated exposure to amphetamine produces long-lasting increases in sensitivity to its effects. We reported previously that repeated amphetamine treatment results in increased astrocytic expression of basic fibroblast growth factor (bFGF) in the ventral tegmental area (VTA) and substantia nigra compacta (SNc) and that this effect is prevented by coadministration of a nonspecific glutamate receptor antagonist. Here we show that the development of sensitization to amphetamine is prevented when amphetamine injections are preceded by infusions of a neutralizing antibody to bFGF into the VTA. In addition, we show that astrocytic bFGF expression is increased in the VTA and SNc of animals that exhibit behavioral sensitization and that the number of bFGF-immunoreactive astrocytes in these regions is strongly and positively correlated with the magnitude of sensitization. Cotreatment with an NMDA glutamate receptor antagonist blocks both the development of behavioral sensitization and bFGF induction. These results show that endogenous bFGF is necessary for the development of sensitization to amphetamine and suggest that bFGF mediates the glutamatergic-dopaminergic interaction that initiates the long-term consequences of repeated drug use.

Amphetamine↗
PubMed2000

Absence of cystatin C mutation in sporadic cerebral amyloid angiopathy-related hemorrhage.

In Icelandic pedigrees a cystatin C mutation, glutamine 68 (L68Q), causes autosomal dominant cerebral amyloid angiopathy-related hemorrhage (CAAH). We examined 33 patients with sporadic CAAH for this mutation. None carried L68Q and, including this report, only one of 52 published cases of sporadic CAAH has had the cystatin C mutation. Despite vascular colocalization of cystatin C with amyloid beta-protein, cystatin C L68Q is rare in sporadic CAAH.

Aged↗
PubMed2000

Prospective study of apolipoprotein E genotype and functional outcome following ischemic stroke.

BACKGROUND: The apolipoprotein E (APOE) epsilon 4 allele is a marker of adverse outcome following head injury and intracerebral hemorrhage. Transgenic animal data in a focal cerebral ischemia model suggest that the epsilon 4 allele increases infarct size and functional impairment. OBJECTIVE: To determine if APOE genotype is associated with functional recovery from ischemic stroke. DESIGN: Prospective study. SETTING: Stroke service at a university teaching hospital. PATIENTS: Patients with clinical and neuroimaging findings (computed tomography or magnetic resonance imaging) compatible with an acute ischemic stroke. MAIN OUTCOME: Functional outcome by Barthel index (BI) and modified Rankin scale (mRS) was compared for epsilon 3/epsilon 3 patients vs epsilon 4 carriers and vs epsilon 2 carriers at 1 and 3 months. Univariate predictors of 3-month outcome were examined in a multivariate analysis. RESULTS: One hundred eighty nine patients were enrolled: 100 women, 89 men (mean +/- SD age, 69.4 +/- 11.0 years). There were 25 epsilon 2 alleles (frequency, 0.07), 292 epsilon 3 alleles (0.77), and 61 epsilon 4 alleles (0.16). Baseline National Institutes of Health Stroke Scale scores and Oxfordshire Community Stroke Project classifications were similar in all groups (epsilon 3/epsilon 3, epsilon 4, and epsilon 2 carriers). One-month (BI, P = .64; mRS, P = .59) and 3-month (BI, P = .87; mRS, P = .73) outcomes were not associated with possession of either epsilon 4 or the epsilon 2 allele. Baseline National Institutes of Health Stroke Scale scores (P < .001) and age (P = .002) were significant predictors of 3-month BI and mRS outcomes in multivariate analyses. CONCLUSIONS: Although there is a robust influence of APOE polymorphism on functional recovery after some types of brain injury in humans, it does not exert a major influence on injury severity or functional recovery following ischemic stroke. Arch Neurol. 2000;57:1480-1484

Adult↗