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Biomedical subjects

J Powell

Publications and source records attributed to J Powell.

At least 37 records · Page 2Linked to original sources
PubMed2001

Semantic memory is impaired in both dementia with Lewy bodies and dementia of Alzheimer's type: a comparative neuropsychological study and literature review.

OBJECTIVE: To test the hypothesis that semantic impairment is present in both patients with dementia with Lewy bodies (DLB) and those with dementia of Alzheimer's type (DAT). METHODS: A comprehensive battery of neuropsychological tasks designed to assess semantic memory, visuoperceptual function, verbal fluency, and recognition memory was given to groups of patients with DLB (n=10), DAT (n=10) matched pairwise for age and mini mental state examination (MMSE), and age matched normal controls (n=15). RESULTS: Both DLB and DAT groups exhibited impaired performance across the range of tasks designed to assess semantic memory. Whereas patients with DAT showed equivalent comprehension of written words and picture stimuli, patients with DLB demonstrated more severe semantic deficits for pictures than words. As in previous studies, patients with DLB but not those with DAT were found to have impaired visuoperceptual functioning. Letter and category fluency were equally reduced for the patients with DLB whereas performance on letter fluency was significantly better in the DAT group. Recognition memory for faces and words was impaired in both groups. CONCLUSIONS: Semantic impairment is not limited to patients with DAT. Patients with DLB exhibit particular problems when required to access meaning from pictures that is most likely to arise from a combination of semantic and visuoperceptual impairments.

Aged↗
PubMed2001

Psychosis and aggression in Alzheimer's disease: the effect of dopamine receptor gene variation.

This study investigated possible associations between selected polymorphisms in the dopamine receptor genes DRD1 and DRD3 with the presence of psychotic phenomena or aggressive behaviour in a community based cohort of 134 patients with late onset Alzheimer's disease. An association was found between the presence of psychotic symptoms and aggressive behaviour and the DRD1 polymorphism and between the presence of psychosis, but not aggression, and the DRD3 polymorphism. Specifically, carriers of the DRD1 B2 allele were more likely to be aggressive or experience hallucinations whereas homozygous carriers of the DRD3 1 allele were more likely to experience delusions.

Age of Onset↗
PubMed2001

Increased common carotid intima-media thickness in UK African Caribbeans and its relation to chronic inflammation and vascular candidate gene polymorphisms.

BACKGROUND AND PURPOSE: Individuals of African Caribbean descent who live in the United Kingdom have an increased risk of stroke. The reasons for this are not fully understood, but differences in genetic predispositions or other novel stroke risk factors could play a role. US blacks have been reported to have increased common carotid artery wall thickness, or intima-media thickness (IMT), measured by ultrasound. We measured carotid IMT in UK African Caribbeans compared with UK whites and determined whether different distributions of polymorphisms in potential candidate vascular genes or differences in measures of chronic inflammation or infection could account for any difference. METHODS: In a population study, common carotid artery IMT was measured in 202 white men and 89 African Caribbean men. The distribution of polymorphisms in ACE, paraoxonase 1, paraoxonase 2, and methylenetetrahydrofolate reductase genes was determined. Serum C-reactive protein and Helicobacter pylori seropositivity were determined. RESULTS: Carotid IMT was increased in African Caribbeans even after controlling for cardiovascular risk factors, including homocysteine and social class: beta=0.113, 95% CI 0.036 to 0.189, P=0.004. There was a significant interaction with smoking and mean IMT (P=0.022), and the difference in both measures of IMT between ethnic groups was largely limited to individuals who had never smoked. There were significant ethnic differences in the distributions of 3 of the 4 candidate genes studied (ACE, paraoxonase 1, and methylenetetrahydrofolate reductase). H pylori seropositivity was increased in African Caribbeans (78.7% versus 53% in UK whites). However, neither the genetic polymorphisms nor H pylori seropositivity was related to IMT, and ethnic differences in their distribution did not account for the increased IMT seen in African Caribbeans. CONCLUSIONS: Carotid IMT is increased in UK African Caribbeans even after controlling for conventional risk factors. There are highly significant ethnic differences in the distribution of many potential cerebrovascular candidate genes. Although those we examined did not explain the ethnic differences in IMT, other genetic predispositions or environmental exposures could account for these differences.

Adult↗
PubMed2001

Professional territories and the fragmented landscape of elderly care.

This paper examines the problems and dilemmas involved in delivering care to older people. In particular it seeks to identify the processes that facilitate or hinder communication and collaboration between those involved in care that has to be both reliable and expeditious to ensure that high quality care is provided. To do this the paper draws on a recent international systematic review of the relevant research literature which is briefly described. A geographical analogy is employed to help map different organisational and professional territories of care. It will be argued that these territories have their own priorities, patterns of working and perceptions of older people. The paper concludes by considering a potential way to merge territorial interests by reconfiguring the map of care around the older person.

Aged↗
PubMed2001

Can brain-injured patients participate in an aerobic exercise programme during early inpatient rehabilitation?

OBJECTIVE: We investigated the capacity of brain-injured patients to participate in an aerobic exercise programme early after injury. DESIGN: Retrospective analysis of exercise achievements in patients participating in a randomized controlled trial. SETTING AND SUBJECTS: Ninety patients participated in an exercise training programme on a cycle ergometer at four inpatient neurological rehabilitation units for younger patients. At intake, impairments and function were rated on: Motricity Index, Ashworth Scale, Berg Balance Scale, Barthel Index and Functional Independence Measure. INTERVENTIONS: Patients cycled for up to 30 minutes three times weekly for 24-36 sessions over 12 weeks. MAIN OUTCOME MEASURES: Exercise performance was measured by: (a) number of sessions to achieve a cycling time of 30 minutes, (b) overall mean cycling time per session over 24 sessions and (c) mean time per session cycling at >60% of age predicted maximum heart rate (HR max) over 24 sessions. RESULTS: Fifty-five patients completed 24 sessions. Thirty-five withdrew, largely for logistic reasons, before completing training; they were significantly less disabled than the 55 who remained. Forty-four of the 55 patients trained for an average of at least 20 minutes per session, 18 training at >60% HR max for this time. There were no differences in performance on the three exercise parameters between two groups of patients with baseline Barthel scores of < or = 12 and > or = 13. CONCLUSIONS: Brain-injured patients with a range of disabilities have the capacity to participate in an exercise programme during early inpatient rehabilitation, though some may take longer to achieve adequate intensity of aerobic exercise.

Adolescent↗
PubMed2000

Mathematical elements of attack risk analysis for mountain pine beetles.

Three different mathematical approaches are combined to develop a spatial framework in which risk of mountain pine beetle (MPB) attack on individual hosts may be assessed. A density-based partial differential equation model describes the dispersal and focusing behavior of MPB. A local projection onto a system of ordinary differential equations predicts the consequences of the density equations at individual hosts. The bifurcation diagram of these equations provides a natural division into categories of risk for each host. A stem-competition model links host vigor to stand age and demographics. Coupled together, these models illuminate spatial risk structures which may also shed light on the role of climatic variables in population outbreaks. Preliminary results suggest that stand microclimate has much greater influence on risk of attack than host vigor and stand age.

Animals↗
PubMed2000

Measurement of excitation functions in the reactions 197Au(11C, xn)208-xAt using a radioactive 11C beam

A light-element radioactive ion-beam capability has been developed at the LBNL 88-Inch Cyclotron. The system is based on the coupled-cyclotrons method and utilizes short-lived species, e.g., 11C, 14O, 13N produced by (p,n) and (p,alpha) reactions at the LBNL Biomedical Isotope Facility Cyclotron. In a first experiment, 197Au(11C,xn)208-xAt excitation functions have been measured for energies ranging from the Coulomb barrier up to 110 MeV using a beam of 11C with intensities up to (1-2)x10(8) ions/sec on target. The results of this experiment are compared to measurements of 197Au(12C, xn)209-xAt excitation functions.

Journal Article↗
PubMed2000

The effect of cocoa procyanidins on the transcription and secretion of interleukin 1 beta in peripheral blood mononuclear cells.

Recent data has demonstrated that cacao liquor polyphenols (procyanidins) have antioxidant activity, inhibit mRNA expression of interleukin-2 and are potent inhibitors of acute inflammation. Given the widespread ingestion of cocoa in many cultures, we investigated whether cocoa, in its isolated procyanidin fractions (monomer through decamer), would modulate synthesis of the pro-inflammatory cytokine, interleukin-1 beta. Both resting and phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) were investigated at the levels of transcription and protein secretion. Individual cocoa fractions were shown to augment constitutive IL-1 beta gene expression, although values varied between subjects. Interestingly, the smaller fractions of cocoa (monomer-tetramer) consistently reduced IL-1 beta expression of PHA-stimulated cells by 1-15%, while the larger oligomers (pentamer-decamer) increased expression by 4-52%. These data, observed at the transcription level, were reflected in protein levels in PHA-induced PBMC. The presence or absence of PHA did not alter the effects of the cocoa procyanidins with the exception of the pentamer. This study offers additional data for the consideration of the health-benefits of dietary polyphenols from a wide variety of foods, including those benefits associated specifically with cocoa and chocolate consumption.

Antioxidants↗
PubMed2000

The association between APOE and dementia does not seem to be mediated by vascular factors.

OBJECTIVE: The effect of APOE on dementia may be mediated through dyslipidemia and atherogenesis through its effect on cholesterol metabolism. The authors investigated this possibility among aged survivors from the UK Medical Research Council Trial of the Treatment of Hypertension in Older Adults. DESIGN: A total of 370 of 657 survivors from an initial cohort of 1,088 recruited into the trial between 1983 and 1985 were traced in 1994 and agreed to be screened for dementia. Blood samples were analyzed for APOE genotype and serum fibrinogen. Cholesterol level, smoking behavior, blood pressure, body mass index, and EKG recordings had been measured at recruitment 10 to 12 years earlier. Odds ratios (ORs) for the association between APOE epsilon4/* and both AD and dementia were estimated and adjusted incrementally for the effect of age and premorbid intelligence, cholesterol, other risk factors for vascular disease, and EKG evidence of cardiovascular disease. RESULTS: The authors diagnosed 24 cases of National Institute of Neurological and Communicative Disorders and Stroke AD from 41 cases of dementia. The crude OR for the association between APOE epsilon4/* and AD was 3.40 (95% CI 1.30 to 8.91). APOE genotype was associated with serum cholesterol level, and there was a nonsignificant trend for an association with smoking behavior. After adjusting for these and all other vascular risk factors and vascular disease variables listed earlier, the OR for the association between APOE epsilon4/* and AD increased to 4.81 (1.60 to 14.4). CONCLUSION: Presence of APOE epsilon4/* seems to increase the risk for dementia and AD independently of its effect on dyslipidemia and atherogenesis.

Aged↗
PubMed2000

Stay on Your Feet Safety Walks Group.

The Safety Walks Group is an initiative that evolved from the Stay on Your Feet Program. The strategies used in this program target both behavioural and environmental change and are based on the five areas for action under the Ottawa Charter (WHO, 1986) and Jakarta Declaration (WHO, 1997). The Safety Walks Group addresses the issue of public hazards via the use of a standard checklist covering pedestrian areas, business houses and accommodation. The project provided a forum for seniors to be proactive, working with the authorities to address the issue of public hazards and make the environment safer.

Accidental Falls↗
PubMed2000

Postpartum contraceptive use among adolescent mothers.

OBJECTIVE: To compare the incidence of repeat pregnancy and method continuation rate at 12 months postpartum in young women who chose either depot medroxyprogesterone acetate or oral contraceptives (OCs) as contraception. METHODS: We conducted a prospective cohort study of 122 postpartum women younger than 18 years of age who delivered between January 8, 1997 and December 31, 1997. Patients choosing depot medroxyprogesterone acetate (n = 76) and OCs (n = 46) were accrued for 12 months and were followed-up for a minimum of 12 months. Main outcome measures were median contraceptive method continuation and the incidence of repeat pregnancy at 12 months postpartum. RESULTS: There was no difference in mean age at delivery (P =.47), parity (P =.84), or gravidity (P =.78) between depot medroxyprogesterone acetate and OC users. At 12 months postpartum, 27.4% of OC users and 55.3% of depot medroxyprogesterone acetate users were still using contraception. Median time to contraceptive discontinuation was longer for those choosing depot medroxyprogesterone acetate compared with OCs (17.8 vs 7.4 months, respectively, P =.002). The overall incidence of repeat pregnancy at 12 months postpartum was 10.6%. Among OC and depot medroxyprogesterone acetate users, respectively, 24% and 2.6% became pregnant again, producing a relative risk (RR) of 9.09 (95% confidence interval [CI] 2.1, 39.2) for repeat pregnancy among OC users. The mean time to repeat pregnancy (this was reported instead of the median time whenever the pregnancy rate had not reached 50% at the end of the follow-up period) was longer for depot medroxyprogesterone acetate compared with OC users (17.1 months vs 13.2 months, respectively, P <.001). CONCLUSION: Adolescent mothers using depot medroxyprogesterone acetate injection for contraception have a higher method continuation rate and a lower incidence of repeat pregnancy at 12 months postpartum than those selecting OCs during the same period.

Adolescent↗
PubMed2000

Activation of AP-1 through the MAP kinase pathway: a potential mechanism of the carcinogenic effect of arenediazonium ions.

Arenediazonium ions such as those found in the common mushroom Agaricus bisporus have been convincingly demonstrated to be tumorigenic. The specific mechanism of their tumorigenicity remains unclear. It has been shown that arenediazonium ions can be metabolized to aryl radicals, and that reaction of these aryl radicals with DNA produces aryl adducts. These metabolic processes also produce the reactive oxygen species superoxide and hydroxyl radicals which have been implicated in AP-1 activation. To further investigate the mechanism of tumorigenesis by arenediazonium ions, we studied the effect of a representative arenediazonium ion on AP-1 activation and phosphorylation of the signal transduction proteins ERK1, ERK2, JNK, and p38 kinase, both in vitro and in vivo. We also identified the specific radicals produced by spin trapping and ESR analysis. Here, it was found that p-methylbenzenediazonium ion (2a) induced a 16-fold increase in the extent of AP-1 activation at micromolar concentrations, and that this increase coincided with phosphorylation of the signaling kinases ERK1 and -2 and p38 kinase, but not JNK, in JB6 mouse epithelial cells. In vivo studies using AP-1 luciferase reporter-bearing transgenic mice supported the increase in the extent of AP-1 activation in 2a-treated mice over controls, and showed that this effect was different in different tissue types. The antioxidant N-acetylcysteine (NAC), a general antioxidant, showed an inhibitory effect on 2a-mediated AP-1 induction, while aspirin, a hydroxyl radical scavenger, had no effect. Spin trapping studies showed that while NAC suppressed radical formation from 2a, aspirin did not alter radical production from 2a. It appears that 3a, a carbon-centered radical formed from 2a, is responsible for AP-1-induced activation, and therefore, radical species that are not oxygen-centered are also capable of inducing AP-1. These results represent a step toward understanding the mechanism of tumorigenicity of arenediazonium ions.

Acetylcysteine↗
PubMed2000

Clouston hidrotic ectodermal dysplasia (HED): genetic homogeneity, presence of a founder effect in the French Canadian population and fine genetic mapping.

HED is an autosomal dominant skin disorder that is particularly common in the French Canadian population of south-west Quebec. We previously mapped the HED gene to the pericentromeric region of chromosome 13q using linkage analysis in eight French Canadian families. In this study, we extend our genetic analysis to include a multiethnic group of 29 families with 10 polymorphic markers spanning 5.1 cM in the candidate region. Two-point linkage analysis strongly suggests absence of genetic heterogeneity in HED in four families of French, Spanish, African and Malaysian origins. Multipoint linkage analysis in all 29 families generated a peak lod score of 53.5 at D13S1835 with a 1 lod unit support interval spanning 1.8 cM. Recombination mapping placed the HED gene in a 2.4 cM region flanked by D13S1828 proximally and D13S1830 distally. We next show evidence for a strong founder effect in families of French Canadian origin thereby representing the first example of a founder disease in the south-west part of the province of Quebec. Significant association was found between HED in these families and all markers analysed (Fisher's exact test, P < 0.001). Complete allelic association was detected at D13S1828, D13S1827, D13S1835, D13S141 and D13S175 (P(excess) = 1) spanning 1.3 cM. A major haplotype including all 10 associated alleles was present on 65% of affected chromosomes. This haplotype most likely represents the founder haplotype that introduced the HED mutation into the French Canadian population. Luria-Delbrück equations and multipoint likelihood linkage disequilibrium analysis positioned the gene at the D13S1828 locus (likely range estimate: 1.75 cM) and 0.58 cM telomeric to this marker (support interval: 3.27 cM) respectively.

Alleles↗
PubMed2000

Lichen sclerosus premenarche: autoimmunity and immunogenetics.

Lichen sclerosus is among the most frequently seen paediatric vulval disorders. In adults a strong association between lichen sclerosus and autoimmune diseases, and also with HLA class II locus DQ7, has been well demonstrated in women and a weaker association in men. These associations have not previously been studied in children, although in other autoimmune diseases, the HLA associations have been strongest in children. We performed HLA tissue typing and looked for autoimmune associations in a group of 30 children with vulval lichen sclerosus. HLA DQ7 was present in 66% of female children with lichen sclerosus compared with 31% in controls. Previous studies reported DQ7 in 51% of adult female patients and 45% of male patients. Sixteen per cent of the children were homozygous for DQ7 as opposed to 5% of controls. In the childhood group, only 4% had another autoimmune disease, but 56% of their parents or grandparents did. Age differences make comparison difficult, but the family history of autoimmunity appears to be strong in the early-onset group, in addition to the stronger association with DQ7.

Adolescent↗
PubMed2000

Skin disorders in relation to oral contraception and other factors, including age, social class, smoking and body mass index. Findings in a large cohort study.

BACKGROUND: Over the years, a substantial number of scientific papers has been published considering the possible relationship between oral contraceptive use and various skin disorders. OBJECTIVES: We aimed to investigate the possible effects of oral contraceptives and other factors including age, social class, smoking and body mass index on the occurrence of hospital referral for skin disorders within the Oxford Family Planning Association (Oxford-FPA) contraceptive study. METHODS: We carried out a cohort study with long-term follow up of 17,032 women aged 25-39 years recruited at 17 family planning centres in England and Scotland between 1968 and 1974. The main outcome measure was the pattern of referral to hospital for skin disorders among the participants. The conditions considered (number of women affected in parentheses) were: malignant melanoma (48); other skin cancers (83); benign skin neoplasms (384); boils and cellulitis (334); eczema and dermatitis (327); erythematous disease (54); psoriasis (92); hypertrophic and atrophic conditions (59); diseases of the nails (80); diseases of the hair and hair follicles (74); diseases of the sebaceous glands (362); pigmented naevi (383); and unspecified eruptions (199). Some of these disease categories are broad, which complicates interpretation of the findings. RESULTS: As the data relate to hospital referrals, while most skin disorders are largely managed within primary care, it is difficult to know to what extent our findings can be generalized to disease patterns in the community. None the less, a number of interesting results emerged. These included increased risks (approximately twofold) of referral to hospital for boils and cellulitis in heavy women, for psoriasis in women who smoke, and for pigmented naevi in women of higher social class. Referral for pigmented naevi was reduced by about half in women with a high body mass index. Of the oral contraceptive associations studied, we consider that only an increased risk of referral for eczema or dermatitis in current or recent pill users (relative risk 1.6, 95% confidence interval 1.2-2.1) might reflect a causal relationship. There was no increased risk in past users nor was the risk related to duration of use. These findings are very similar to those reported from the Royal College of General Practitioners oral contraception study. CONCLUSIONS: Hospital referral for certain skin disorders was related to age, social class, smoking and body mass index within the Oxford-FPA study. Hospital referral for skin disorders generally seems to be unrelated to oral contraceptive use within the study, the possible exception being eczema and dermatitis, which occur more commonly in current and recent pill users than in non-users.

Adult↗