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J Simpson

Publications and source records attributed to J Simpson.

At least 37 records · Page 2Linked to original sources
PubMed2004

Genotypic and phenotypic characterization of drug-resistant Mycobacterium tuberculosis isolates from rural districts of the Western Cape Province of South Africa.

Genotypic and phenotypic analysis of drug-resistant Mycobacterium tuberculosis isolates from the Western Cape Province of South Africa showed that drug resistance is widespread and recently transmitted. Multidrug-resistant (MDR) isolates comprise 40% of this collection, and a large pool of isoniazid monoresistance may be a future source of MDR tuberculosis.

DNA Primers↗
PubMed2004

Health impacts of flooding in Lewes: a comparison of reported gastrointestinal and other illness and mental health in flooded and non-flooded households.

Severe flooding may become more frequent due to global warming. A historical cohort study was conducted by telephone interview for new episodes of illness in all age groups, and for psychological distress in adults, following severe river flooding on 12 October 2000 in the town of Lewes in Southern England. Two hundred and twenty-seven residents of 103 flooded households and 240 residents of 104 non-flooded households in the same postal district were recruited by random selection of addresses from a post flooding survey and a commercial database respectively. Having been flooded was associated with earache (RR 2.2 [1.1,4.1] p = 0.02), and a significant increase in risk of gastroenteritis with depth of flooding (RR 1.7 [0.9,3.0] p = 0.09, p for trend by flood depth = 0.04). Adults had a four-times higher risk of psychological distress defined as a score of > or = 4 in response to the 12-item General Health Questionnaire (GHQ-12) (RR 4.1 [2.6, 6.4] p < 0.0005, p for trend by flood depth = 0.01). Associations between flooding and new episodes of physical illness in adults diminished after adjustment for psychological distress. Flooding remained highly significantly associated with psychological distress after adjustment for physical illnesses. Psychological distress may explain some of the excess physical illness reported by flooded adults and possibly by children as well. Policies to promote population resilience to flooding where flood prevention has failed must include practical support for flood victims and provision of appropriate psychological support. Associations with physical illnesses affirm the need for advice and assistance with individual, household and environmental hygiene and access to medical services.

Adolescent↗
PubMed2003

Vitamin K and childhood cancer: a report from the United Kingdom Childhood Cancer Study.

The relationship between neonatal vitamin K received by the intramuscular (i.m.) route and the development of leukaemia or other cancers was investigated as part of a national case-control study of childhood cancer, using data abstracted from obstetric and neonatal records. The analyses included 2530 children diagnosed with cancer before 15 years of age, 1174 of whom had leukaemia and 4487 control children without cancer. Overall, 39% of cases and 42% of controls had records of i.m. vitamin K administration, while 24% of cases and 22% of controls had no record of whether or not they had received vitamin K. Using subjects who received i.m. vitamin K as the baseline group, our analyses found no association between the administration of i.m. vitamin K and either leukaemia or other cancers as a group. We conclude that there is no convincing evidence that neonatal vitamin K administration, irrespective of the route by which it is given, influences the risk of children developing leukaemia or any other cancer.

Adolescent↗
PubMed2003

Origin of symptoms in diverticular disease.

BACKGROUND: A significant number of patients with colonic diverticula experience unexplained, recurrent, short-lived but often debilitating abdominal pain and alteration in bowel habit. Such patients account for many medical consultations every year but, as our understanding of the cause of their symptoms remains imperfect, treatment options are limited. This article reviews the possible mechanisms that may be responsible for the symptoms of diverticular disease. METHODS: Medline and Science Citation Index searches were performed to locate English language articles relating to colonic diverticula and symptoms published between January 1966 and July 2002. Manual cross-referencing was also performed and some historical articles were included. RESULTS AND CONCLUSION: Several theories now exist about the mechanisms underlying the symptoms of diverticular disease. Initial studies suggested that they may be due to alterations in the intracolonic pressure, extrapolating earlier thoughts on the likely pathogenesis of diverticula. It seems more likely, however, that several inter-related processes, such as muscular dysfunction, visceral hypersensitivity and inflammation, are involved in symptom generation.

Abdominal Pain↗
PubMed2003

High-pressure freezing in the study of animal pathogens.

High-pressure freezing is applicable to both morphological and immunocytochemical studies. We are investigating the morphogenesis of foot-and-mouth disease virus and African swine fever virus by the use of high-pressure freezing of infected cells. Foot-and-mouth disease virus particles are not detected in sections of conventionally immersion-fixed infected cells, but when the cells are prepared by high-pressure freezing, newly formed virions are readily seen throughout the cell. We report two methods for high-pressure freezing of virally infected cells: first, two sapphire discs frozen 'face to face' with a narrow spacer to prevent cell damage and, second, a fibrous filter substrate that can be easily cut into discs to fit into the freezing planchettes. Cells readily adhere to the fibres in vitro, and the complete disc can be rapidly transferred to the planchettes for freezing. Immunolabelling studies of the microneme proteins of the parasite Eimeria tenella indicate that high-pressure freezing followed by freeze-substitution in acetone with uranyl acetate allows high-sensitivity immunolabelling for these proteins.

African Swine Fever Virus↗
PubMed2002

Exposure to power frequency electric fields and the risk of childhood cancer in the UK.

The United Kingdom Childhood Cancer Study, a population-based case-control study covering the whole of Great Britain, incorporated a pilot study measuring electric fields. Measurements were made in the homes of 473 children who were diagnosed with a malignant neoplasm between 1992 and 1996 and who were aged 0-14 at diagnosis, together with 453 controls matched on age, sex and geographical location. Exposure assessments comprised resultant spot measurements in the child's bedroom and the family living-room. Temporal stability of bedroom fields was investigated through continuous logging of the 48-h vertical component at the child's bedside supported by repeat spot measurements. The principal exposure metric used was the mean of the pillow and bed centre measurements. For the 273 cases and 276 controls with fully validated measures, comparing those with a measured electric field exposure >/=20 V m(-1) to those in a reference category of exposure <10 V m(-1), odds ratios of 1.31 (95% confidence interval 0.68-2.54) for acute lymphoblastic leukaemia, 1.32 (95% confidence interval 0.73-2.39) for total leukaemia, 2.12 (95% confidence interval 0.78-5.78) for central nervous system cancers and 1.26 (95% confidence interval 0.77-2.07) for all malignancies were obtained. When considering the 426 cases and 419 controls with no invalid measures, the corresponding odds ratios were 0.86 (95% confidence interval 0.49-1.51) for acute lymphoblastic leukaemia, 0.93 (95% confidence interval 0.56-1.54) for total leukaemia, 1.43 (95% confidence interval 0.68-3.02) for central nervous system cancers and 0.90 (95% confidence interval 0.59-1.35) for all malignancies. With exposure modelled as a continuous variable, odds ratios for an increase in the principal metric of 10 V m(-1) were close to unity for all disease categories, never differing significantly from one.

Adolescent↗
PubMed2002

Quadrupole moments of highly deformed structures in the A approximately 135 region: probing the single-particle motion in a rotating potential.

The latest generation gamma-ray detection system, GAMMASPHERE, coupled with the Microball charged-particle detector, has made possible a new class of nuclear lifetime measurement. For the first time differential lifetime measurements free from common systematic errors for over 15 different nuclei ( >30 rotational bands in various isotopes of Ce, Pr, Nd, Pm, and Sm) have been extracted at high spin within a single experiment. This comprehensive study establishes the effective single-particle transition quadrupole moments in the A approximately 135 light rare-earth region. Detailed comparisons are made with theoretical calculations using the self-consistent cranked mean-field theory which convincingly demonstrates the validity of the additivity of single-particle quadrupole moments in this mass region.

Journal Article↗
PubMed2002

Methenamine hippurate for preventing urinary tract infections.

BACKGROUND: Methenamine salts are often used for the prevention of urinary tract infection (UTI). OBJECTIVES: To assess the effectiveness of methenamine hippurate in preventing UTI. SEARCH STRATEGY: Published and unpublished randomised controlled trials were identified from the Cochrane Controlled Trials Register, MEDLINE, EMBASE, CINAHL, Current Contents, reference lists of review articles and retrieved trials. The manufacturers' of methenamine salts were contacted for unpublished studies and contact was made with known investigators in the area. SELECTION CRITERIA: Randomised and quasi-randomised trials of methenamine hippurate used for the prevention of UTIs in all population groups were eligible for inclusion. A comparison with a control (no treatment) group was a prerequisite to selection. DATA COLLECTION AND ANALYSIS: Two reviewers (BL and TB) performed independent assessment and data extraction using a standardised format. Discrepancies, methodological and interpretative issues were discussed with JS or JC. An exploration of heterogeneity as well as a detailed description of results grouped by population was conducted. MAIN RESULTS: Eleven studies met the inclusion criteria. All trials were included in a descriptive analysis. Seven trials were included in meta-analyses. Four trials (199 patients) studied symptomatic bacteriuria and six trials (341 patients) studied bacteriuria as an outcome measure. Overall, trial quality was poor. The direction of six of the pooled trials was towards a favourable treatment effect from methenamine hippurate. Interpretation of the pooled estimates was not done in view of underlying heterogeneity. The study by Pettersson 1989 explained some, but not all, of the underlying heterogeneity. This study differed from all others by including patients with known upper renal tract abnormalities. Adverse reactions were mentioned by 10 studies. The rate of adverse events was low. REVIEWER'S CONCLUSIONS: There is not enough evidence to conclusively support the use of methenamine hippurate for urinary prophylaxis. An exploration of heterogeneity raises the (hypothesis generating) possibility that methenamine hippurate may have some efficacy in patients without but not in patients with known upper renal tract abnormality (with asymptomatic bacteriuria as the outcome measure). Due to the small sample size and methodological problems within the studies involved, interpretation of these data should be done cautiously. The rate of adverse events reported by the trials was low, which suggests that current usage is unlikely to be causing significant harm.

Anti-Infective Agents, Urinary↗
PubMed2002

Pathogenesis of colonic diverticula.

BACKGROUND: Diverticula are herniations through the colonic wall and are therefore likely to be due to a weakness within the wall, an alteration in intracolonic pressures or a combination of these factors. This article reviews these aspects in relation to the pathogenesis of colonic diverticula. METHODS: Medline and Science Citation Index searches were performed to locate English language articles relating to the pathogenesis of colonic diverticulosis published since 1960. Manual cross-referencing was also performed and some historical articles were included. RESULTS AND CONCLUSION: Several theories now exist about the development of colonic diverticula. The majority of the evidence suggests that the morphological changes are the response to a lifelong consumption of a low-residue diet. However, there are complex relations between colonic structure, motility and dietary factors, and it is likely that all of these (and possibly genetic influences) play a role in the pathogenesis to a greater or lesser degree.

Age Factors↗
PubMed2002

Airway inflammation in thunderstorm asthma.

BACKGROUND: Epidemics of acute asthma associated with thunderstorms occur intermittently worldwide, though airway inflammation during these acute episodes has not been characterized. The aim of this study was to characterize airway inflammation in thunderstorm asthma. METHODS: Cases were recruited after presentation to the emergency room with acute asthma immediately following a thunderstorm (n = 6). They were compared to two control groups: a group of atopic asthmatics that had presented with acute asthma to the emergency room prior to the thunderstorm (n = 12), and a second group of corticosteroid naive asthmatics who presented to the emergency room in the prior 12 months (n = 6). Subjects had spirometry, sputum induction and allergy skin tests acutely and at review 4 weeks later. RESULTS: Thunderstorm (TS) cases were more likely to have a history of hay fever and grass pollen allergy, and less likely to be on inhaled corticosteroids (ICS) prior to presentation. Cases and control groups had a similar degree of moderate to severe acute airway obstruction (P = 1.0). TS cases had elevated sputum eosinophils (14.8% of total cell count) compared to controls (1%, 2.6%, P < 0.01). TS cases had higher sputum eosinophil cationic protein (ECP; 11,686 ng/mL) compared to controls (1,883, 3,300, P = 0.02) acutely. TS cases had more cells positive for IL-5 (30%) compared to controls (1, 1.5%, P = 0.02). When adjusted for ICS use, TS cases had a risk ratio for elevated sputum eosinophils of 2.4 (1.23-4.69). CONCLUSION: Thunderstorm asthma is characterized by airway inflammation with IL-5-mediated sputum eosinophilia and eosinophil degranulation. These results are consistent with allergen exposure as the cause of the exacerbation, and are consistent with the thunderstorm-induced grass pollen deluge as the cause of epidemic asthma after thunderstorms.

Acute Disease↗
PubMed2002

Kinetics of changes in lymphocyte sub-populations in mouse lungs after intrapulmonary infection with M. bovis (Bacillus Calmette-Guerin) and identity of cells responsible for IFNgamma responses.

Gamma interferon (IFNgamma) plays a key role in host defense against pulmonary mycobacterial infections. A variety of lymphocyte subsets may participate in producing pulmonary IFNgamma responses, but their relative contributions after mycobacterial infection have not been clearly elucidated. To address this question, C57Bl/6 female mice were infected by intrapulmonary instillation of 2.5 x 104 BCG (Mycobacterium bovis Bacillus Calmette-Guerin). Lymphocyte populations in lung interstitium were examined at different time points after the infection. BCG load in lungs peaked between 4 and 6 weeks post-infection and declined to very low levels by the 12th week of infection. Recovery of lung interstitial lymphocytes doubled by 4-6 weeks after infection and declined thereafter. Flow cytometric analysis of the lung-derived lymphocytes revealed that about 5% of the these cells made IFNgamma in control mice, and this baseline IFNgamma production involved T (CD3+NK1.1-), NK (CD3-NK1.1+) and NKT (CD3+NK1.1+) cells. As the BCG lung infection peaked, the total number of CD3+ T cells in the lungs increased threefold at 5-6 weeks post-infection. There was a marked increase (sixfold) in the number of T cells secreting IFNgamma 5-6 weeks post-infection. Some increase was also noted in the NKT cells making IFNgamma, but the numbers of NK cells making IFNgamma in BCG-infected lungs remained unaltered. Our results suggest that whereas NK and NKT cells contribute to baseline IFNgamma secretion in control lungs, expansion in the IFNgamma-producing T-cell population was essentially responsible for the augmented response seen in lungs of BCG-infected mice.

Animals↗
PubMed2002

Cough, airway inflammation, and mild asthma exacerbation.

BACKGROUND: Prospective data on the temporal relation between cough, asthma symptoms, and airway inflammation in childhood asthma is unavailable. AIMS AND METHODS: Using several clinical (diary, quality of life), lung function (FEV(1), FEV(1) variability, airway hyperresponsiveness), cough (diary, cough receptor sensitivity (CRS)), and inflammatory markers (sputum interleukin 8, eosinophilic cationic protein (ECP), myeloperoxidase; and serum ECP) of asthma severity, we prospectively described the course of these markers in children with asthma during a non-acute, acute, and resolution phase. A total of 21 children with asthma underwent these baseline tests; 11 were retested during days 1, 3, 7, and 28 of an exacerbation. RESULTS: Asthma exacerbations were characterised by increased asthma and cough symptoms and eosinophilic inflammation. Sputum ECP showed the largest increase and peaked later than clinical scores. Asthma scores consistently related to cough score only early in the exacerbation. Neither CRS nor cough scores related to any inflammatory marker. CONCLUSION: In mild asthma exacerbations, eosinophilic inflammation is dominant. In asthmatic children who cough as a dominant symptom, cough heralds the onset of an exacerbation and increased eosinophilic inflammation, but cough scores and CRS do not reflect eosinophilic airway inflammation.

Acute Disease↗
PubMed2002

Atypical presentation of tuberculosis meningitis: a case report.

A 19 year old woman presented with atypical symptoms of tuberculous meningitis. Meningitis is the most serious form of tuberculosis (TB) and it often presents with nonspecific signs and symptoms. Delayed diagnosis can result in rapid progression of neurological deficits and poor prognosis. Polymerase chain reaction and other nucleic acid amplification methods are becoming increasingly useful for the rapid detection of Mycobacterium tuberculosis in the cerebrospinal fluid. Early treatment reduces morbidity and mortality of this serious condition.

Adult↗
PubMed2001

The tolerability, safety, and success of sputum induction and combined hypertonic saline challenge in children.

Induced sputum using hypertonic saline (HS) is a useful research tool to study airway inflammation (AI). HS provocation testing can also be used to measure airway hyperresponsiveness (AHR). A combined HS challenge and sputum induction procedure has been developed to permit assessment of AI and AHR in a single test. The aim of this study is to report the success and tolerability of sputum induction alone, and in combination with a HS bronchial provocation challenge. Sputum induction alone was performed with beta2-agonist pretreatment. In the combined challenge, no beta2-agonist pretreatment was used. A high-output ultrasonic nebulizer with valve box and tubing were used to deliver 4.5% saline in doubling time periods from 0.5 s to 4 min. Outcomes assessed were completion of the test protocol, adequacy of sputum samples, decrease in FEV1, and adverse effects during the procedure. Fifty-three children who underwent a sputum induction alone, and 182 children who underwent a combined sputum induction and bronchial provocation using HS. Sputum induction alone was well tolerated, with 98% of children completing the procedure and only 4% experiencing a significant (> 15%) fall in FEV1. An adequate sample of sputum was obtained in 92% of children. The combined challenge was completed by 90% of children. A distressing cough occurred in 13% of children and irritation of the mucosa in 1% of children. In the combined challenge an adequate sample of sputum was obtained in significantly fewer children than with sputum induction alone (70% versus 92%, p < 0.05). Sputum cellular changes reflected the shorter nebulization time with sputum induction alone. We conclude that induction of sputum using HS after pretreatment with bronchodilator is well tolerated with a high success rate in children. Combining the HS challenge with sputum induction provides additional information and is a useful means of comparing AHR and AI simultaneously, but at the expense of having a reduced success rate in obtaining an adequate sample of sputum, as well as increased side effects.

Adolescent↗
PubMed2001

Characterization of asphalt fume composition under simulated road paving conditions by GC/MS and microflow LC/quadrupole time-of-flight MS.

A highly sensitive, selective, and reliable analytical method has been developed and validated for characterization of asphalt fume generated under simulated road paving conditions. A dynamic asphalt fume generation system was modified to provide consistent test atmospheres at simulated asphalt road paving conditions. In the process of fume generation, asphalt was initially preheated in an oven to 170 degrees C, pumped to a large kettle, which maintained the asphalt temperature between 150 and 170 degrees C, and then transferred to the generator. The fume was conducted from the generator to an exposure chamber through a heated transfer line. Characterization of the asphalt fume test atmospheres included the following: (1) determination of the consistency of the asphalt aerosol composition within the generation system; (2) quantification of total organic matter of the asphalt fume by electron impact ionization of isotope dilution gas chromatography/ mass spectrometry); and (3) identification of individual priority polycyclic aromatic hydrocarbons (PAHs) in asphalt fume by selected ion monitoring. With the developed method, asphalt fumes could be characterized into three fractions: (1) filter collection of a large molecular size fraction over a range of mass-to-charge (m/z) ratios of 173-309; (2) XAD-2 trapping of a medium molecular size fraction over a range of m/z ratios of 121-197; and (3) charcoal trapping of a small molecular size fraction that contained mainly the volatile vapor fraction over a range of m/z ratios of 57-141. Total organic matter of the asphalt fume was quantified over the 5 exposure days. Sixteen specific priority PAHs were monitored and identified. These PAHs were determined at trace levels on the filter fraction. A novel approach, which utilizes collision-induced dissociation of fragmentation pathway leading to a characteristic fragmentation pattern by coupling microflow liquid chromatography to atmospheric pressure chemical ionization of quadrupole time-of-flight mass spectrometry, was used to further clarify the trace amount of key components present in simulated road paving asphalt fumes. These results demonstrate that asphalt fume composition could be characterized and specific priority PAHs could be identified by this method. The major advantages of this method are its highly sensitivity, selectivity, and reliability for chemical hazard characterization in a complex mixture. This method is suitable for support toxicity studies using simulated occupational exposure to asphalt fumes.

Carcinogens, Environmental↗
PubMed2001

Cyclin-dependent kinase inhibitor p27(Kip1) is required for mouse mammary gland morphogenesis and function.

We have studied the role of the cyclin-dependent kinase (Cdk) inhibitor p27(Kip1) in postnatal mammary gland morphogenesis. Based on its ability to negatively regulate cyclin/Cdk function, loss of p27 may result in unrestrained cellular proliferation. However, recent evidence about the stabilizing effect of p27 on cyclin D1-Cdk4 complexes suggests that p27 deficiency might recapitulate the hypoplastic mammary phenotype of cyclin D1-deficient animals. These hypotheses were investigated in postnatal p27-deficient (p27(-/-)), hemizygous (p27(+/)-), or wild-type (p27(+/+)) mammary glands. Mammary glands from p27(+/)- mice displayed increased ductal branching and proliferation with delayed postlactational involution. In contrast, p27(-/-) mammary glands or wild-type mammary fat pads reconstituted with p27(-/-) epithelium produced the opposite phenotype: hypoplasia, low proliferation, decreased ductal branching, impaired lobuloalveolar differentiation, and inability to lactate. The association of cyclin D1 with Cdk4, the kinase activity of Cdk4 against pRb in vitro, the nuclear localization of cyclin D1, and the stability of cyclin D1 were all severely impaired in p27(-/-) mammary epithelial cells compared with p27(+/+) and p27(+/-) mammary epithelial cells. Therefore, p27 is required for mammary gland development in a dose-dependent fashion and positively regulates cyclin D-Cdk4 function in the mammary gland.

Active Transport, Cell Nucleus↗