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Biomedical subjects

C Brown

Publications and source records attributed to C Brown.

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

Automated mutation screening using dideoxy fingerprinting and capillary array electrophoresis.

The rapid progress in the isolation of genes associated with human disease has resulted in an increasing demand for mutation screening methods. The molecular diagnosis of the long QT syndrome (LQTS), a cardiac disorder characterized by prolongation of the QT(c) interval in the ECG, syncopes, and sudden death, requires mutation screening of all exons in at least five genes, encoding cardiac Na(+) and K(+) channel subunits. A method for automated dideoxy fingerprinting (ddF) using capillary array electrophoresis (CAE) was developed and the efficiency of the method was tested by analyzing 24 DNA samples with mutations in one of the genes KCNQ1 and KCNH2, which are involved in 50% of LQTS cases. One of these mutations, 362insQK in KCNQ1, is novel. The sensitivity was 100% using a single electrophoresis temperature of 18 degrees C or 25 degrees C. However, analysis of the samples in both the sense and anti-sense direction were required for high sensitivity. Analysis in a single direction resulted in a decrease of the sensitivity to 74% and 70%, respectively. The throughput of the ddF method, if performed with a 16 capillary CAE instrument, is 288 samples per seven hr if each sample is analyzed on both strands.

Automation↗
PubMed2001

HLA-B typing by reference strand mediated conformation analysis using a capillary-based semiautomated genetic analyzer.

The application of reference strand conformation analysis (RSCA) to HLA-A typing using the ABI PRISM 310 capillary based genetic analyzer has recently been described. This study outlines the development and validation of capillary RSCA for HLA-B typing. Mobility values for 93 HLA-B alleles were defined following electrophoresis of known controls through the system. Three fluorescently labelled references, labelled with three different dyes can be electrophoresed simultaneously. The technique was validated by comparing results from 296 cord blood donors with those obtained using reverse SSO. Following capillary RSCA 14.5% of samples required confirmatory typing, compared with a repeat rate of 5.1% following reverse SSO. In samples where no other typing was necessary there was 100% correlation between the two methods. Capillary RSCA for HLA-B typing is quick, easy to implement, and with the introduction of new FLRs and gel matrices has the potential to evolve into a high resolution typing method.

Alleles↗
PubMed2001

Absence of germline and somatic p53 alterations in children with sporadic brain tumors.

Cancers of the central nervous system are the most common solid tumors of childhood. Although somatic alterations of the p53 tumor suppressor gene have been implicated in brain tumorigenesis, the role of germline p53 mutations in the development of childhood brain tumors has not been well defined. As a component of an ongoing extensive study of the epidemiology of childhood brain tumors, we prospectively examined the germline and tumor p53 gene status in 85 children without a family history of cancer who were diagnosed with a sporadic malignant central nervous system tumor. Using PCR/single-strand conformational polymorphism analysis and direct DNA sequencing, 85 children were screened for the presence of constitutional p53 sequence alterations in exons 2 and 4 through 11. No mutations were identified. Commonly reported sequence polymorphisms were observed at codon 72, as well as in 2 other previously described nucleotide residues. Forty-four brain tumor samples were available for analysis and of these 40 were paired with peripheral blood. Once again, no p53 mutations were found. Of the 5 germline samples with the 2 common polymorphisms, only one had a paired tumor sample for comparison and the tumor contained the same alteration as the germline. Of note, one tumor, a PNET of the cerebellum (medulloblastoma), showed loss of heterozygosity at codon 72. We can conclude that the frequency of germline and somatic p53 mutations in sporadic childhood brain tumors is very low, probably less than 1%, and there is no need to screen these patients routinely for their germline p53 status. However, the potential significance of LOH at codon 72 remains to be elucidated.

Brain Neoplasms↗
PubMed2001

A novel HLA allele, B*4104, identified in a cord blood donor.

Results from a number of HLA typing methods prompted the DNA sequencing (SBT) of a cord blood sample at the HLA-B locus. A novel HLA-B allele, B*4104, was identified. This was confirmed by sequencing the mother of the cord blood unit for HLA-B.

Alleles↗
PubMed2001

How important is intrinsic spirituality in depression care? A comparison of white and African-American primary care patients.

We used a cross-sectional survey to compare the views of African-American and white adult primary care patients (N = 76) regarding the importance of various aspects of depression care. Patients were asked to rate the importance of 126 aspects of depression care (derived from attitudinal domains identified in focus groups) on a 5-point Likert scale. The 30 most important items came from 9 domains: 1) health professionals' interpersonal skills, 2) primary care provider recognition of depression, 3) treatment effectiveness, 4) treatment problems, 5) patient understanding about treatment, 6) intrinsic spirituality, 7) financial access, 8) life experiences, and 9) social support. African-American and white patients rated most aspects of depression care as similarly important, except that the odds of rating spirituality as extremely important for depression care were 3 times higher for African Americans than the odds for whites.

Adolescent↗
PubMed2001

Pulmonary morbidity in 100 survivors of congenital diaphragmatic hernia monitored in a multidisciplinary clinic.

BACKGROUND/PURPOSE: In 1990, the authors began a multidisciplinary follow-up clinic for congenital diaphragmatic hernia (CDH) patients. Although the nonpulmonary complications associated with CDH have been reported previously from this clinic, the purpose of this report is to detail the pulmonary outcome in survivors of CDH with severe pulmonary hypoplasia. METHODS: Between 1990 and 1999, one hundred patients were seen in the clinic. Before hospital discharge, all patients had baseline tests performed, which were repeated per protocol at clinic during follow-up. The data were analyzed by regression analysis to identify and determine the impact of factors on outcomes associated with the long-term pulmonary morbidity. RESULTS: The average birth weight was 3.16 kg (+/-0.7) with a mean Apgar score of 7 (+/- 2) at 5 minutes. Forty-one patients had an antenatal diagnosis performed. Extracorporeal membrane oxygenation (ECMO) was utilized in 29 patients, and a patch repair was required in 32, whereas 16 patients received both. Average time to extubation was 20.7 (+/- 20) days and mean time to discharge was 59.7 (+/- 61) days. Regression analysis showed that both the need for ECMO and a patch repair were independent predictors of delay in extubation (P <. 001, R(2) = 36%), and delay in discharge from the hospital (P =.001, R(2) = 29%). ECMO also was significantly correlated with the need for diuretics at discharge (P <.001, R(2) = 18%), and with the presence of left-right mismatch (P =.009, R(2) = 9%) and V/Q mismatch (P =.005, R(2) = 11%) on subsequent pulmonary ventilation-perfusion examinations. Sixteen patients required O(2) at discharge, and diuretics were necessary in 43 patients. Seventeen patients at discharge required bronchodilators, and during the first year an additional 36 required at least transient therapy. Similarly, 6 patients at discharge required steroids, and an additional 35 patients required at least transient therapy during the first year. Chest x-rays, although frequently abnormal, had little correlation with clinical outcome, but did influence medical therapy. V/Q scans had limited utility in patient management, and the presence of V/Q mismatch was not highly specific for future obstructive airway disease. Nevertheless, V/Q mismatch was sensitive for obstructive airway disease assessed by spirometry. Twenty-five patients over 5 years of age performed pulmonary function tests (PFTs), which showed 72% normal PFT results and 28% with evidence of obstructive airway disease. Before January 1997, 2 of 8 patients who required urgent treatment in the emergency department (ED) were admitted to the intensive care unit (ICU) secondary to acute respiratory distress. After the implementation of respiratory syncytial viral prophylaxis in January 1997, 8 patients were treated in the ED for acute respiratory distress, but none required admission to the ICU. CONCLUSIONS: Pulmonary problems continue to be a source of morbidity for survivors of CDH long after discharge. The need for ECMO and the presence of a patch repair are both predictive of more significant morbidity, but the data clearly show that non-ECMO CDH survivors also require frequent attention to pulmonary issues beyond the neonatal period. These data show the need for long-term follow-up of CDH patients preferably with a multidisciplinary team approach.

Extracorporeal Membrane Oxygenation↗
PubMed2001

Providing information on complementary and alternative therapies and practitioners by producing a directory of practitioners.

This article describes the experience of the authors in producing a booklet to provide information on complementary and alternative therapies (CAM) in their local area. The practical steps needed to produce a booklet are described, including ways of involving local general practitioners, meeting with local therapists, recruiting contact persons for each therapy, designing and producing a booklet and launching the final version. The feedback from general practitioners and CAM practitioners is reported.

Complementary Therapies↗
PubMed2001

Primary care physicians' attitudes, knowledge, and practices related to cancer clinical trials.

BACKGROUND: Participation of patients in cancer clinical trials is disappointingly low and several physician-based factors are thought to be responsible. METHODS: In 1998-1999, the National Cancer Institute (NCI) conducted a probability survey of three primary care physician groups to gain a better understanding of the barriers to clinical-trial patient accrual from their perspective. RESULTS: Findings from this survey of 706 primary care physicians indicate that the vast majority (98%) refer their patients with cancer to a specialist for cancer treatment and rarely bring up the topic of cancer clinical trials. Frequently cited reasons for not mentioning clinical trials are preferring to leave that discussion to the oncologist (41%) and being unaware of any clinical trials that may be available for the patient (37%). CONCLUSION: Primary care physicians may represent an important untapped resource for introducing the concept of clinical trials as an option to newly diagnosed cancer patients.

Clinical Trials as Topic↗
PubMed2001

Primary care patients' personal illness models for depression: a preliminary investigation.

BACKGROUND: Despite the fact that more than half of depressed persons are treated for this disorder by primary care physicians, depression is often under-recognized or treated inadequately. There is continued emphasis on effective treatment of depression in primary care patients, but little attention has been paid to the role of the depressed person's illness cognitions in coping with this disorder. Given the often recurring and chronic nature of depression, the individual's self-management strategies may be critical to effective treatment, recovery and remaining well. OBJECTIVES: The purpose of this pilot study was to determine whether primary care patients' personal illness cognitions for depression are associated with depression coping strategies and treatment-related behaviour. METHODS: Forty-one primary care patients with depressive symptoms or disorder completed interviews and questionnaires assessing illness cognitions for depression, depression coping strategies and other treatment-related behaviour. Descriptive statistics are used to present patients' illness cognitions for depression. t-tests and correlational analyses were completed to assess the relationship between illness cognitions, depression coping strategies and treatment-related behaviour. RESULTS: Preliminary data describing illness cognitions for depression are presented. Participants' illness cognitions for depression were significantly associated with current and past treatment-seeking behaviour, medication adherence and coping strategies. CONCLUSIONS: Although preliminary, these findings indicate that patients' understanding of depression and its consequences are associated with how they manage this illness. Future research is needed to examine the mediating and moderating effects of illness cognitions for depression on medication adherence and other self-management behaviours of depressed primary care patients. Knowledge about primary care patients' personal illness models will aid in the development of adherence interventions, self-management training and support services appropriate to patients' needs in the primary care setting.

Adaptation, Psychological↗
PubMed2001

Antiviral efficacy and pharmacokinetics of oral adefovir dipivoxil in chronically woodchuck hepatitis virus-infected woodchucks.

The antiviral efficacy of orally administered adefovir dipivoxil was evaluated in an 18-week study (12 weeks of treatment and 6 weeks of recovery) conducted with woodchucks chronically infected with woodchuck hepatitis virus (WHV). Adefovir dipivoxil is a prodrug of adefovir designed to enhance its oral bioavailability. Following administration of 15 mg of adefovir dipivoxil per kg of body weight in four WHV-infected animals, the mean maximum concentration of adefovir in serum was 0.462 microg/ml, with an elimination half-life of 10.2 h, and the oral bioavailability of adefovir was estimated to be 22.9% (+/-11.2%). To study antiviral efficacy, the animals were divided into three groups. There were six animals each in a high-dose group (15 mg/kg/day) and a low-dose group (5 mg/kg/day). A vehicle control group consisted of five animals because WHV DNA was detectable only by PCR at the time of the study in one of the original six animals. Efficacy was evaluated by determining the levels of WHV DNA in serum. The geometric mean WHV DNA level for the high-dose group diminished by >40-fold (>1.6 log(10)) after 2 weeks of treatment and >300-fold (>2.5 log(10)) at 12 weeks. There was a >10-fold reduction in five of six low-dose animals by 2 weeks, but levels were unchanged in one animal. By 12 weeks of treatment there was a >45-fold (>1.6 log(10)) reduction of WHV DNA levels, and serum WHV DNA levels were below the limit of quantification in three of six animals. Viral DNA levels returned to pretreatment levels during the 6-week recovery period. There were no clinically significant changes in body weight, hematology, or serum chemistry values, including bicarbonate or lactate, in any of the treated animals. No histologic evidence of liver injury was apparent in the biopsies. Under the conditions of this study, adefovir dipivoxil was an effective antihepadnaviral agent.

Adenine↗
PubMed2001

Quorum-sensing genes in Pseudomonas aeruginosa biofilms: their role and expression patterns.

Acylated homoserine lactone molecules are used by a number of gram-negative bacteria to regulate cell density-dependent gene expression by a mechanism known as quorum sensing (QS). In Pseudomonas aeruginosa, QS or cell-to-cell signaling controls expression of a number of virulence factors, as well as biofilm differentiation. In this study, we investigated the role played by the las and rhl QS systems during the early stages of static biofilm formation when cells are adhering to a surface and forming microcolonies. These studies revealed a marked difference in biofilm formation between the PAO1 parent and the QS mutants when glucose, but not citrate, was used as the sole carbon source. To further elucidate the contribution of lasI and rhlI to biofilm maturation, we utilized fusions to unstable green fluorescent protein in concert with confocal microscopy to perform real-time temporal and spatial studies of these genes in a flowing environment. During the course of 8-day biofilm development, lasI expression was found to progressively decrease over time. Conversely, rhlI expression remained steady throughout biofilm development but occurred in a lower percentage of cells. Spatial analysis revealed that lasI and rhlI were maximally expressed in cells located at the substratum and that expression decreased with increasing biofilm height. Because QS was shown previously to be involved in biofilm differentiation, these findings have important implications for the design of biofilm prevention and eradication strategies.

Bacterial Proteins↗
PubMed2001

Porcine encephalomyocarditis virus persists in pig myocardium and infects human myocardial cells.

Recent advances toward using pig tissues in human transplantation have made it necessary to determine the risk of transmitting zoonotic viruses from pigs to humans or vice versa. We investigated the suitability of the porcine encephalomyocarditis virus (EMCV) model for such studies by determining its ability to persist in pigs, escape detection by routine serological methods, and infect human cells. Intraperitoneal inoculation of 5-week-old pigs with EMCV-30, a strain isolated from commercial pigs, resulted in acute cellular degeneration, infiltration of lymphocytes, and apoptosis in myocardium in 13 of 15 (86.7%) pigs during the acute phase of disease (3 to 21 days postinfection), followed by less-severe lymphocytic infiltration and apoptosis in 5 of 10 (50%) pigs during the chronic phase of the disease (day 45 to 90 postinfection). In the brain, lymphocytic infiltration, neuronal degeneration, and gliosis were observed in 26 to 33% of pigs in the acute phase of disease whereas perivascular cuffing was the predominant feature during chronic disease. EMCV antigens and RNA were demonstrated in the myocardium and brain during the chronic phase of disease. Analysis of 100 commercial pigs that were negative for EMCV antibodies identified two pig hearts positive for EMCV RNA. Porcine EMCV productively infected primary human cardiomyocytes as demonstrated by immunostaining using a monoclonal antibody specific for EMCV RNA polymerase, which is expressed only in productively infected cells, and by a one-step growth curve that showed production of 100 to 1,000 PFU of virus per cell within 6 h. The findings that porcine EMCV can persist in pig myocardium and can infect human myocardial cells make it an important infectious agent to screen for in pig-to-human cardiac transplants and a good model for xenozoonosis.

Animals↗
PubMed2001

Requirement of protein tyrosine phosphatase SHP2 for NO-stimulated vascular smooth muscle cell motility.

We have previously reported that nitric oxide (NO) increases the motility of differentiated cultured primary aortic smooth muscle cells from adult rats. There is little information on the role of protein tyrosine phosphatases in vascular biology. One such phosphatase, Src homology 2 phosphatase 2 (SHP2), is essential for motility. We tested the hypothesis that NO increases SHP2 levels via a cGMP-mediated mechanism and that this effect is necessary for NO-stimulated cell motility. Here we report that two different NO donors increased SHP2 protein levels and enzyme activity. This effect was mimicked by several cGMP agonists and blocked by an inhibitor of guanylyl cyclase. Specific decrease of SHP2 protein levels via the use of antisense oligodeoxynucleotides (ODNs), but not several control ODNs attenuated the motogenic effect of NO, which indicates the involvement of SHP2 in NO-elicited motogenesis. S-nitroso-N-acetylpenicillamine failed to increase SHP2 protein levels in subcultured aortic smooth muscle cells. This provides a potential explanation for the lack of effect of NO on cell motility in dedifferentiated subcultured cells. These results support the hypothesis that NO-elicited upregulation of SHP2 via a cGMP-mediated pathway is necessary for NO-induced motogenesis in differentiated aortic smooth muscle cells.

Animals↗
PubMed2001

GM-CSF mediates alveolar macrophage proliferation and type II cell hypertrophy in SP-D gene-targeted mice.

Mice deficient in surfactant protein (SP) D develop increased surfactant pool sizes and dramatic changes in alveolar macrophages and type II cells. To test the hypothesis that granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates alveolar macrophage proliferation and activation and the type II cell hypertrophy seen in SP-D null mice, we bred SP-D and GM-CSF gene-targeted mice to obtain littermate double null, single null, and wild-type mice. Bronchoalveolar lavage levels of phospholipid, protein, SP-D, SP-A, and GM-CSF were measured from 1 to 4 mo. There was an approximately additive accumulation of phospholipid, total protein, and SP-A at each time point. Microscopy showed normal macrophage number and morphology in GM-CSF null mice, numerous giant foamy macrophages and hypertrophic type II cells in SP-D null mice, and large but not foamy macrophages and mostly normal type II cells in double null mice. These results suggest that the mechanisms underlying the alveolar surfactant accumulation in the SP-D-deficient and GM-CSF-deficient mice are different and that GM-CSF mediates some of the macrophage and type II cell changes seen in SP-D null mice.

Animals↗
PubMed2001

Long-term results of arthroscopic partial lateral meniscectomy in knees without associated damage.

We evaluated the outcome of partial lateral meniscectomy of 31 knees in 29 patients whose knees were otherwise normal. The mean follow-up was 10.3 years. According to the Lysholm score, 14 knees were rated as excellent, four as good, five as fair and eight as poor, with a mean score of 80.5 points. Radiologically, only one lateral compartment was classified as grade 0, eight as grade 1, nine as grade 2, 11 as grade 3, and two as grade 4 according to Tapper and Hoover. No significant (p < 0.05) correlation was found between the amount of tissue resected and the subjective, clinical and radiological outcome. Although early results of lateral meniscectomy may be satisfactory, we have demonstrated that in the long term there was a high incidence of degenerative changes, a high rate of reoperation (29%) and a relatively low functional outcome score.

Adult↗
PubMed2001

Management of acute exacerbations of COPD: a summary and appraisal of published evidence.

STUDY OBJECTIVES: To critically review the available data on the diagnostic evaluation, risk stratification, and therapeutic management of patients with acute exacerbations of COPD. DESIGN, SETTING, AND PARTICIPANTS: English-language articles were identified from the following databases: MEDLINE (from 1966 to week 5, 2000), EMBASE (from 1974 to week 18, 2000), HealthStar (from 1975 to June 2000), and the Cochrane Controlled Trials Register (2000, issue 1). The best available evidence on each subtopic then was selected for analysis. Randomized trials, sometimes buttressed by cohort studies, were used to evaluate therapeutic interventions. Cohort studies were used to evaluate diagnostic tests and risk stratification. Study design and results were summarized in evidence tables. Individual studies were rated as to their internal validity, external validity, and quality of study design. Statistical analyses of combined data were not performed. MEASUREMENT AND RESULTS: Limited data exist regarding the utility of most diagnostic tests. However, chest radiography and arterial blood gas sampling appear to be useful, while short-term spirometry measurements do not. In terms of the risk of relapse and the risk of death after hospitalization for an acute exacerbation, there are identifiable clinical variables that are associated with these outcomes. Therapies for which there is evidence of efficacy include bronchodilators, corticosteroids, and noninvasive positive-pressure ventilation. There is also support for the use of antibiotics in patients with more severe exacerbations. Based on limited data, mucolytics and chest physiotherapy do not appear to be of benefit, and oxygen supplementation appears to increase the risk of respiratory failure in an identifiable subgroup of patients. CONCLUSIONS: Although suggestions for appropriate management can be made based on available evidence, the supporting literature is spotty. Further high-quality research is needed and will require an improved, generally acceptable, and transportable definition of the syndrome "acute exacerbation of COPD" and improved methods for observing and measuring outcomes.

Acute Disease↗