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Biomedical subjects

J Simpson

Publications and source records attributed to J Simpson.

At least 73 records · Page 4Linked to original sources
PubMed2000

Biallelic methylation and silencing of mouse Aprt in normal kidney cells.

Heritable gene silencing is an important mechanism of tumor suppressor gene inactivation in a variety of human cancers. In the present study, we show that methylation-associated silencing of the autosomal adenine phosphoribosyltransferase (Aprt) locus occurs in primary mouse kidney cells. Aprt-deficient cells were isolated from mice that were heterozygous for Aprt, i.e., they contained one wild-type Aprt allele and one targeted allele bearing an insertion of the bacterial neo gene. Although silencing of the wild-type allele alone was sufficient for the cells to become completely Aprt-deficient, biallelic methylation of the promoter region was found to occur. Moreover, despite the absence of selective pressure against the targeted allele, phenotypic silencing of the inserted neo gene accompanied silencing of the wild-type Aprt allele. A potential role for allelic homology in these events is discussed.

Adenine↗
PubMed2000

Oligosaccharides related to xyloglucan: synthesis and X-ray crystal structure of methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-alpha-D-x ylopyranoside and the synthesis of methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-beta-D-xy lopyranoside.

Trisaccharides, methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-alpha-D-xy lopyranoside and methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-beta-D-xyl opyranoside, which are related to the side chain of xyloglucan have been synthesised. The beta-galactopyranosyl linkage of each was constructed using silver trifluoromethanesulfonate-promoted glycosylations of 2-O-acetyl-3,4,6-tri-O-benzyl-beta-D-galactopyranosyl chloride and the corresponding anomer of methyl 3,4-tri-O-benzyl-D-xylopyranoside. The resulting disaccharides were deacetylated and fucosylated using assisted halide reactions with tri-O-benzyl-alpha-L-fucopyranosyl bromide. Hydrogenolytic debenzylation of the resulting protected trisaccharides gave the methyl glycosides of the fucose-containing xyloglucan side chain. The structure of methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-alpha-D-xy lopyranoside as the monohydrate was confirmed by an X-ray crystallographic study.

Carbohydrate Sequence↗
PubMed2000

Tyrosine kinase activation in response to fungal spores is primarily dependent on endogenous reactive oxygen production in macrophages.

Studies from our laboratory (Shahan, T. A., Sorenson, W. G., and Lewis, D. M. (1994) Environ. Res. 67, 98-104) demonstrated that spores from different fungal species differentially activate rat alveolar macrophages as detected by the measurement of superoxide anion and cytokine production (Shahan, T. A., Siegel, P. D., Sorenson, W. G., Kuschner, W. G., and Lewis, D. M. (1998) Am. J. Respir. Cell Mol. Biol. 18, 435-441). Spores from Aspergillus candidus stimulated production of the highest levels of superoxide anion (5.2 nmol/1.0 x 10(6) alveolar macrophages (AMs)/30 min), followed by those from Aspergillus niger (2.4 nmol/1.0 x 10(6) AMs/30 min) and Eurotium amstelodami (0.4 nmol/1.0 x 10(6) AMs/30 min). The mechanism of this differential activation was studied. Our data demonstrate that the tyrosine kinases p56(Hck), p72(Syk), p77(Btk), p62(Yes), p56(Lck), and p59(Fyn) were specifically activated in response to spores from A. candidus, whereas spores from either A. niger or E. amstelodami activated p56(Hck), p72(Syk), and p77(Btk). Kinetic analysis of specific tyrosine kinases demonstrated that p56(Hck), p72(Syk), and p77(Btk) were activated faster and to a greater extent by spores from A. candidus as compared with spores from E. amstelodami. These data suggest a relationship between reactive oxygen species and tyrosine kinase activation. Treatment of AMs with H(2)O(2) (1 mM) caused the activation of p72(Syk) only, whereas treatment with superoxide dismutase and catalase before treatment with the spores had no effect on tyrosine kinase activation. Incubation with NADPH oxidase inhibitors inhibited both superoxide anion production and the activation of p56(Hck), p72(Syk), and p77(Btk) in response to fungal spores. These data indicate that endogenous reactive oxygen species are necessary for the activation of p56(Hck), p72(Syk), and p77(Btk) by spores; they also indicate that some species of spores are capable of activating tyrosine kinases independent of superoxide anion.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed2000

Change counselling in diabetes: the development of a training programme for the diabetes team.

Skills in counselling for behaviour change may help staff working in diabetes care to facilitate self management in people with diabetes. A feasibility study was conducted to define the essential competencies (attitudes, knowledge and skills), training methods, and assess whether this approach was practicable in a diabetes resource centre. Semi structured interviews with staff were routinely conducted throughout the duration of the study. The findings suggest that the stages of change model, motivational interviewing and behavioural techniques are relevant to work in this area. Acquiring the competencies was harder to achieve than anticipated, though most were evident after one years training. The most valued training methods were individual supervision and video examples. However, the competencies were difficult to apply in the clinical setting given time constraints, the strength of existing staff routines and the patients' readiness to change. The lessons learned and suggestions for future work are presented.

Competency-Based Education↗
PubMed2000

Induced sputum eosinophils and neutrophils and bronchiectasis severity in allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity reaction to the fungus Aspergillus fumigatus that may progress to bronchiectasis. The aim of the present study was to characterize airway inflammation in patients with clinically stable ABPA and asthma, and to correlate this with bronchiectasis severity. Subjects with ABPA and central bronchiectasis (ABPA-CB; n=16) and ABPA with serological evidence alone (ABPA-S; n=10) were studied. Comparison groups were A. fumigatus-sensitized asthma (n=19), non-A. fumigatus-sensitized asthma (n=15) and healthy controls (n=8). Hypertonic saline challenge, sputum induction and high-resolution computed tomography (HRCT) of the chest were performed. Sputum eosinophil numbers were markedly elevated in ABPA-CB (median 8.4%) compared to ABPA-S (2.4%), A. fumigatus-sensitized asthma (1.8%), asthma (1.8%) and controls (0.3%) (p<0.01); sputum eosinophil cationic protein levels were higher in ABPA-CB (median 13,706 ng.mL(-1)), compared to ABPA-S (1,633.5 ng.mL(-1)), A. fumigatus-sensitized asthma (1,550.7 ng.mL(-1)), asthma (309.2 ng.mL(-1)), and controls (110 ng.mL(-1)) (p<0.001). ABPA-CB also showed increased sputum neutrophil number (median 60.3%) compared to the other groups (controls 29.3%) (p=0.01). The severity of bronchiectasis on HRCT correlated with sputum neutrophil (r=0.6) and eosinophil number (r=0.5) but not serum immunoglobulin-E levels. In conclusion, clinically stable allergic bronchopulmonary aspergillosis with bronchiectasis is characterized by an intense heterogenous inflammatory infiltrate consisting of eosinophils and neutrophils, which correlates closely with the severity of bronchiectasis on high-resolution computed tomography. Sputum analysis may be useful in monitoring the course of allergic bronchopulmonary aspergillosis.

Adult↗
PubMed2000

Characterisation of human adenylyl cyclase IX reveals inhibition by Ca(2+)/Calcineurin and differential mRNA plyadenylation.

The functional diversity of adenylyl cyclases provides for different modes of cyclic AMP signalling in mammals. This study reports the cloning and functional characterisation of a cDNA encoding human adenylyl cyclase IX (ACIX). The data show that human ACIX is a Ca(2+)/calcineurin-inhibited adenylyl cyclase prominently expressed in vital organs, including brain, heart, and pancreas. ACIX mRNA was detected in several brain regions, including neocortex, hippocampus, striatum, and cerebellum. By in situ hybridisation, ACIX mRNA was localised to pyramidal and granule cells of the hippocampus, indicating that it is expressed predominantly in nerve cells. Further analysis of ACIX mRNA expression revealed two major forms of ACIX mRNA that arose through tissue-specific differential mRNA polyadenylation. Taken together, the data show that (a) human ACIX is under inhibitory control by Ca(2+) through calcineurin, (b) ACIX may be involved in higher brain functions, and (c) post-transcriptional regulation of ACIX gene expression is a species-specific control mechanism that may enhance the versatility of cyclic AMP signalling in humans.

3' Untranslated Regions↗
PubMed2000

An outbreak of Serratia marcescens in two neonatal intensive care units.

Outbreaks of infection in neonatal intensive care units (NICUs) due to Serratia marcescens are well recognized. In some outbreaks no point source has been found, whereas in others cross-infection has been associated with contaminated ventilator equipment, disinfectants, hands and breast pumps. We report an outbreak due to S. marcescens that involved two geographically distinct NICUs. The outbreak occurred over a six week period; 17 babies were colonized, 12 at Glasgow Royal Maternity Hospital (GRMH) and five at the Queen Mothers Hospital (QMH). At GRMH three babies developed septicaemia, of whom two died. The outbreak isolates were of the same serotype and phage type and were indistinguishable on the basis of restriction fragment length polymorphism analysis. During the outbreak, two babies shown consistently to be negative on screening, were transferred between the two units. In addition, two members of medical staff attended both units. In QMH no means of cross infection was identified. However, in GRMH the outbreak strain of S. marcescens was isolated from a laryngoscope blade and a sample of expressed breast milk.

Breast Feeding↗
PubMed2000

Neonatal neurological testing in resource-poor settings.

The aim of the study was to design and test a neurological examination for newborns that could be performed reliably by paramedical staff in resource-poor settings. The examination was adapted from a method established by Dubowitz et al., the latest version of which includes an optimality score. The final items in the test were chosen because they were culturally acceptable, could be elicited according to strict but easily comprehensible instructions and because the expected responses could be scored by the descriptions given or by diagrams in the proforma. The shortened examination was easily taught to paramedical staff who achieved a high degree of inter-observer reliability. This shortened version of the examination was piloted by comparing newborns from a Karen refugee camp on the western border of Thailand and from a large maternity hospital in Bangkok with a standardized cohort of newborns in London. The modified shortened version of the test was sufficiently sensitive to identify a number of differences between the cohorts, notably the poor vision performance and markedly reduced tone of the Karen newborns. In conclusion, the test can be used very reliably by paramedical staff and is a useful, simple and portable tool for the neurological assessment of newborn babies where resources are limited.

Allied Health Personnel↗
PubMed2000

Interleukin-8 secretion and neutrophil recruitment accompanies induced sputum eosinophil activation in children with acute asthma.

Although airway inflammation is recognized as a key feature of asthma, the characteristics of airway inflammation in children with acute severe asthma are not well defined. The aim of this study was to describe the characteristics of airway inflammation in children with an acute exacerbation of asthma using sputum cell counts and fluid-phase measurements and to examine the changes in these parameters upon resolution of the exacerbation. Children (n = 38) presenting to the Emergency Department with acute asthma underwent successful sputum induction using ultrasonically nebulized normal saline (n = 22), or expectorated sputum spontaneously (n = 16). Sputum induction was repeated at least 2 wk later when the children had recovered (n = 28). Sputum portions were selected, dispersed and total and differential cell counts performed. Neutrophil elastase and EG2-positive eosinophils were assessed and fluid-phase eosinophil cationic protein (ECP), myeloperoxidase (MPO), interleukin-8 (IL-8), and IL-5 were measured. During the acute exacerbation the median (range) total cell count was 8.4 x 10(6)/ml (0.5 to 190.3), and fell significantly at resolution to 1.3 x 10(6)/ml (p < 0.01). The inflammatory cell infiltrate was mixed and included eosinophils (0.8 x 10(6)/ml), neutrophils (3.3 x 10(6)/ml), and mast cells. EG2(+) cells were high and correlated with the degree of airflow obstruction (r = -0.5, p = 0.02). They decreased significantly at resolution as did supernatant ECP (1,078 versus 272 ng/ml), suggesting that eosinophils were activated during the exacerbation. MPO was 220 ng/ ml at exacerbation and fell significantly to 1 ng/ml at resolution. Levels of IL-8 and IL-5 were elevated during the acute exacerbation and IL-8 concentrations decreased at resolution. In conclusion, airway inflammation can be studied in children with acute asthma by sputum induction. Airway inflammation is present during an acute exacerbation of asthma, and is characterized by infiltration and activation of both eosinophils and neutrophils. The heterogeneity of airway inflammation in acute asthma may influence response to corticosteroid therapy.

Acute Disease↗
PubMed2000

CYP2D6 inhibition by fluoxetine, paroxetine, sertraline, and venlafaxine in a crossover study: intraindividual variability and plasma concentration correlations.

The authors report the CYP2D6 inhibitory effects of fluoxetine, paroxetine, sertraline, and venlafaxine in an open-label, multiple-dose, crossover design. Twelve CYP2D6 extensive metabolizers were phenotyped, using the dextromethorphan/dextrorphan (DM/DX) urinary ratio, before and after administration of fluoxetine 60 mg (loading dose strategy), paroxetine 20 mg, sertraline 100 mg, and venlafaxine 150 mg. Paroxetine, sertraline, and venlafaxine sequences were randomized with 2-week washouts between treatments; fluoxetine was the last antidepressant (AD) administered. Comparing within groups, baseline DM/DX ratios (0.017) were significantly lower than DM/DX ratios after treatment (DM/DXAD) with fluoxetine (0.313, p < 0.0001) and paroxetine (0.601, p < 0.0001) but not for sertraline (0.026, p = 0.066) or venlafaxine (0.023, p = 0.485). Between groups, DM/DXAD ratios were significantly higher for fluoxetine and paroxetine compared to sertraline and venlafaxine. No differences between DM/DXAD ratios were found for fluoxetine and paroxetine although more subjects phenocopied to PM status after receiving the latter (42% vs. 83%; chi 2 = 4.44, p = 0.049, df = 1). Similarly, no differences between DM/DXAD ratios were found for sertraline and venlafaxine. Of note, the DM/DXAD for 1 subject was much lower after treatment with paroxetine (0.058) compared to fluoxetine (0.490), while another subject exhibited a much lower ratio after treatment with fluoxetine (0.095) compared to paroxetine (0.397). Significant correlations between AD plasma concentration and DM/DXAD were found for paroxetine (r2 = 0.404, p = 0.026) and sertraline (r2 = 0.64, p = 0.002) but not fluoxetine or venlafaxine. In addition, DM/DXAD correlated with baseline isoenzyme activity for paroxetine, sertraline, and venlafaxine groups. These results demonstrate the potent, but variable, CYP2D6 inhibition of fluoxetine and paroxetine compared to sertraline and venlafaxine. CYP2D6 inhibition may be related, in part, to dose, plasma concentration, and baseline isoenzyme activity, and these correlations merit further investigation.

Chromatography, High Pressure Liquid↗
PubMed2000

Public health implications of dengue in personnel returning from East Timor.

In north Queensland the vector of dengue fever (Aedes aegypti) is present; hence any viraemic individual importing dengue has the potential to transmit the disease locally. In early 2000 approximately 2,000 personnel returned from East Timor to Townsville, north Queensland. Seven importations of dengue occurred and individual cases were viraemic for up to 6 days in Townsville. No subsequent local transmission occurred. There were 3 cases each of dengue type 2 and dengue type 3. One case could not be serotyped. A response, including mosquito control measures, was initiated in another 18 cases in which dengue fever was clinically suspected but which subsequently proved not to be dengue. The planning and processes undertaken to prevent local transmission of dengue in Townsville during an intense period are described.

Dengue↗
PubMed2000

A pilot study of neoadjuvant paclitaxel and radiation with correlative molecular studies in stage II/III breast cancer.

A commonly used approach to the management of locally advanced breast cancer currently involves neoadjuvant chemotherapy, followed by surgery and radiation. Earlier neoadjuvant regimens had utilized doxorubicin, making concurrent treatment with radiation less desirable given dose-limiting normal tissue toxicities. With the development of paclitaxel, we can now reconsider the use of concurrent chemoradiation in the treatment of breast cancer. Although paclitaxel is a known radiation sensitizer, its precise mechanism of action is still unclear. One of its proposed mechanisms is that it binds tubulin and induces an M-phase arrest. As cells in M-phase are very sensitive to radiation, it thereby increases radiation sensitivity. The ability to predict tumor response for individual patients would allow us to tailor subsequent therapy for the individual patient. This study is designed to evaluate if paclitaxel's effects on the cell cycle of an individual patient can predict the responsiveness of that patient's tumor to paclitaxel and radiation. Patients will be treated with 3 cycles of paclitaxel followed by concurrent paclitaxel and radiation prior to definitive surgery.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Traumatic diaphragmatic rupture: associated injuries and outcome.

A retrospective case note analysis was performed on all patients treated for traumatic diaphragmatic rupture (TDR) at a major teaching hospital between January 1990 and August 1998. Patients were identified from the prospectively maintained UK Trauma and Research Network Database. Of the 480 cases of torso trauma admitted during the study period, 16 (3.3%) had TDR. Blunt trauma accounted for 13 (81%) of the injuries. A radiological pre-operative diagnosis was made in 10 (62.5%) patients. Seven of these were made on initial chest radiography, two on ultrasound scan and one on computed tomography. All patients underwent a midline laparotomy and TDR was subsequently diagnosed at operation in 6 patients. The left hemidiaphragm was ruptured in 14 (87.5%) patients and there was visceral herniation in 8 (50%). Twelve patients with blunt trauma had associated abdominal and extra-abdominal injuries, but only one of the three patients with penetrating trauma had other injuries. The median Injury Severity Score (range) was 21 (9-50). The median time (range) spent on the intensive care unit was 2 days (0-35 days). Pulmonary complications occurred in 7 (44%) patients. Two (12.5%) patients died from associated head injuries. TDR results from blunt and penetrating torso trauma, is uncommon, rarely occurs in isolation and is associated with a high morbidity and mortality. A high index of suspicion makes early diagnosis more likely as initial physical and radiological signs may be lacking.

Adolescent↗
PubMed1999

A new system for catheter ablation of atrial fibrillation.

Increased attention is now being focused on developing new technologies to cure atrial fibrillation using catheter ablation techniques. The performance of a MAZE-type procedure using standard catheter ablation technologies is arduous and is associated with an unacceptable risk of complications. The Guidant Heart Rhythm Technologies Linear Ablation System was developed to create long transmural linear lesions. Unique features of this system include the availability of different preshaped multi-electrode steerable ablation catheters, the use of phased radiofrequency (RF) energy, and the control of RF output by varying the duty cycle. A prospective multicenter clinical trial to evaluate the safety and efficacy of a right atrial ablation procedure using this technology to treat atrial fibrillation is currently underway. To date, 15 patients have been enrolled and the procedure was acutely effective in 14 of 15 patients with no complications. Atrial fibrillation has recurred during short-term follow-up in 12 of 15 patients, a not surprising result, because this initial phase of testing involved only right-sided ablation. The early results of the phase I clinical trial confirm the findings of others that successful ablation of chronic atrial fibrillation is likely to require a left atrial approach. This clinical trial, as well as others that are currently underway, will be invaluable in the continuing development of catheter ablation of atrial fibrillation and, ultimately, in determining if the routine use of this therapeutic tool can become a reality.

Atrial Fibrillation↗