Search PubMed⌕ Search

Biomedical subjects

J M Drazen

Publications and source records attributed to J M Drazen.

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

Automated detection of single nucleotide polymorphism in beta-2 adrenergic receptor gene using LCx(R).

Beta-2 adrenergic receptor (B2AR) agonists are the most widely prescribed rescue agents used in the treatment of asthma. Recent studies have indicated a relationship between a polymorphism at codon 16 of the B2AR gene, and the response to recurrent beta-agonist therapy. The B2AR polymorphism of interest involves a single nucleotide change from A to G, resulting in an amino acid change from Arginine (Arg) to Glycine (Gly). Clinical efforts to further investigate this relationship require an accurate, reliable and inexpensive method for detecting the polymorphism. In this study, we report an LCx(R) assay for the detection of a single nucleotide polymorphism at codon 16 of the beta-2 adrenergic receptor. This assay is capable of detecting patients harboring any of the three possible genotypes at this locus, namely, homozygous wild type, homozygous variant or heterozygous individuals with a single genomic DNA sample of 25-500 ng. It requires minimum hands-on time with automated detection. The assay would be suitable for use in research labs for screening of a large number of samples. We believe that this type of assay will facilitate research and clinical investigations in elucidating the association of SNPs with disease states, diagnosis, prognosis and treatment.

Adrenergic beta-Agonists↗
PubMed2001

Genetic analysis in the Asthma Clinical Research Network.

Because there is reason to believe that genetic variants could account for different treatment responses in subjects with asthma, it is important to collect blood for genetic-analysis purposes when conducting clinical trials in asthma. This article describes issues related to maintaining subject confidentiality, tracking and shipping blood samples, quality control procedures at the laboratory performing the genotyping, and necessary data verification checks when implementing the genetic-analysis database for the Asthma Clinical Research Network.

Adrenergic beta-Agonists↗
PubMed2001

DNA sequence variants of the platelet-derived growth factor A-chain gene.

BACKGROUND: Platelet-derived growth factor A-chain (PDGF-A) is a potent connective tissue mitogen implicated in lung growth and development. PDGF-A may have a role in asthma through effects on fibroblasts and bronchial smooth muscle cells. OBJECTIVE: To test the hypothesis that there exist variations in the PDGF-A gene associated with the asthma phenotype. METHODS: We screened genomic DNA from normal and asthmatic subjects using single-stranded conformational polymorphism (SSCP) for mutations in the promoter and all seven exons of the gene. RESULTS: Four transition polymorphisms (three novel) were identified: one each in exons 3 and 4 (overall population allele frequencies 0.18 and 0.02, respectively) which did not alter the protein sequence, one in exon 4 (frequency 0.005) which resulted in a valine to isoleucine substitution, and one in intron 5 (frequency 0.5). The intron 5-sequence variant is close to the 3' end of exon 5 but does not appear to affect alternative splicing of PDGF-A exon 6 RNA. The frequencies of the polymorphisms in exons 3 and intron 5 did not differ between the asthmatic and non-asthmatic subjects, but there was a significant frequency difference between Caucasian and African-American subjects for each of these polymorphisms (P = 0.03 and 0.003, respectively). CONCLUSION: No association was found between the sequence variants in the PDGF-A gene and the development of asthma. However, the allele frequency of some of the sequence variants differed between the Caucasian and African-American subjects.

Asthma↗
PubMed2001

Variant eotaxin: its effects on the asthma phenotype.

BACKGROUND: Eotaxin, a CC chemokine expressed in the asthmatic lung, has been associated with impaired lung function. The role of its variant form is unknown. OBJECTIVE: The purpose of this study was to detect the population frequency and effects of a known single-nucleotide polymorphism in the eotaxin gene in which a threonine residue (THR(23)) is substituted for the wild-type alanine (ALA(23)) at the 23rd amino acid at the terminus of the peptide leader sequence. METHODS: We measured eotaxin protein secretion in 293 cells transfected with expression vectors and in PBMCs obtained from individuals bearing the alternative forms of the gene. A case-control study of plasma eotaxin levels and eosinophil counts, a comparison of baseline lung function by genotype in a population of 806 subjects with asthma, and a comparison of the allele frequency with a nonasthmatic population were performed. RESULTS: Human 293 cells and PBMCs with THR(23) variant eotaxin secreted significantly less eotaxin protein than did ALA(23)-bearing cells. In the case-control study, THR(23)-THR(23) individuals had lower plasma levels of eotaxin (310 [240-350] vs 420 [270-700] pg/mL; P < .05) and eosinophil counts (120 [5-220] vs 190 [110-470] cells/microL; P < .05) than ALA(23)-ALA(23) subjects; heterozygous subjects had intermediate levels. Higher levels of lung function were associated with THR(23) eotaxin (percent of predicted FEV(1), 65% +/- 3.5% [THR(23)-THR(23)] vs 58% +/- 0.9% [THR(23)-ALA(23)] and 56% +/- 0.5% [ALA(23)-ALA(23)]; P < .05). CONCLUSION: The THR(23) variant is associated with both decreased eosinophil counts and higher levels of lung function in subjects with asthma.

Adult↗
PubMed2001

The transcription factor early growth-response factor 1 modulates tumor necrosis factor-alpha, immunoglobulin E, and airway responsiveness in mice.

Early growth-response factor 1 (Egr-1) is a sequence-specific transcription factor that plays a regulatory role in the expression of many genes important in inflammation, cell growth, apoptosis, and the pathogenesis of disease. In vitro studies suggest that Egr-1 is capable of regulating the expression of tumor necrosis factor-alpha (TNF-alpha) and other genes involved in airway inflammation and reactivity following allergen stimulation. On the basis of these data, we hypothesized that in the absence of Egr-1, the TNF-alpha response and subsequent downstream inflammatory events that usually follow allergen challenge would be diminished. To test our hypothesis Egr-1 knock-out (KO) mice were examined in an ovalbumin (OVA)-induced model of airway inflammation and reactivity, and compared with identically treated wild-type (WT) control mice. In response to OVA sensitization and airway challenge, KO mice had diminished TNF-alpha mRNA and protein in the lungs and mast cells compared with WT mice. Interestingly, the KO mice had elevated IgE levels at baseline and after allergen challenge compared with WT mice. Furthermore, the airways of KO mice were hyporesponsive to methacholine challenge at baseline and after allergen challenge. These data indicate that Egr-1 modulates TNF-alpha, IgE, and airway responsiveness in mice.

Animals↗
PubMed2001

Clinical predictors of health-related quality of life depend on asthma severity.

The National Asthma Education and Prevention Program guidelines define asthma severity before treatment by lung function and symptoms. It has been assumed, but not demonstrated, that improvement in these measures would translate into improvement in health-related quality of life (HRQL). Because HRQL is an important outcome in asthma management, we asked what are the determinants of HRQL? To address this question, we retrospectively analyzed HRQL data, as measured by the Juniper Asthma Quality of Life Questionnaire, in subjects with mild versus moderate-severe asthma from two clinical trials. We examined whether these traditional clinical outcomes have different relationships to HRQL depending on asthma severity. We also assessed whether the relationship between clinical outcomes and HRQL in subjects with moderate-severe asthma would change when subjects improved to mild-moderate disease with controller medication treatment. Lung function was not an independent predictor or determinant of HRQL at any level of asthma severity, whereas intensity of shortness of breath predicted HRQL at all levels of asthma severity. Rescue beta-agonist use independently predicted HRQL in subjects with mild asthma, but not in those with moderate-severe asthma. In subjects with moderate-severe asthma who improved to mild-moderate disease with controller treatment, rescue beta-agonist use predicted HRQL. We conclude that the independent determinants of HRQL vary according to asthma severity and change with asthma treatment.

Adult↗
PubMed2001

Association of asthma with beta(2)-adrenergic receptor gene polymorphism and cigarette smoking.

Recent studies have suggested that two polymorphisms of the beta(2)-adrenergic receptor (beta(2)AR) gene at codons 16 (arginine to glycine) and 27 (glutamine to glutamate) affect an individual's airway responsiveness, or response to acute or chronic beta(2)-agonist therapy but are not risk factors for asthma. We hypothesize that there is an interaction effect on asthma between the beta(2)AR gene polymorphisms and cigarette smoking. A case-control study was conducted in 128 asthma cases and 136 control individuals identified from 10,014 studied subjects in rural Anqing, China. Allele-specific polymerase chain reaction (PCR) was used to genotype beta(2)AR gene polymorphisms. Multiple logistic regression was used to adjust for potential confounding factors. We found a marginally significant interaction between cigarette smoking and beta(2)AR-16 genotype after adjusting for important confounding factors (p = 0.06). Specifically, we found that compared with never-smoking Gly-16 homozygotes, those ever-smokers who are Arg-16 homozygotes had a significantly increased risk of asthma (odds ratio [OR] = 7.81; 95% confidence interval [CI]: 2.07 to 29.5). This association showed a clear dose-response relationship with the number of cigarettes smoked. However, there was no significant association of asthma with polymorphisms of the beta(2)AR at position 27 (OR = 1.38; 95% CI: 0.69 to 2.73). Our study suggests a gene-environment interaction between the Arg-16 genotype and ever cigarette smoking with respect to the susceptibility of an individual to asthma.

Adult↗
PubMed2001

Safety and reproducibility of sputum induction in asthmatic subjects in a multicenter study.

The safety of sputum induction and the reproducibility of measurements in induced sputum in multicenter studies is unknown. We examined the safety of sputum induction in a two-visit, six-center study in 79 subjects with moderate to severe asthma (mean +/- SD FEV(1) 71 +/- 12% predicted, 67% taking inhaled corticosteroids). In addition, we compared the reproducibility of markers of inflammation in induced sputum with the reproducibility of the FEV(1) and the methacholine PC(20). The FEV(1) decreased > or = 20% from the postbronchodilator baseline in 14% of all subjects and in 25% of subjects whose initial prebronchodilator baseline was 40 to 60% of predicted. All subjects responded promptly to additional albuterol treatment, and no subject developed refractory bronchoconstriction requiring treatment other than reversal of bronchospasm in the study laboratory. The reproducibility of measurements of the eosinophil percentage, eosinophil cationic protein, tryptase, and methacholine PC(20) were similar (concordance correlation coefficients of 0.74, 0.81, 0.79, and 0.74, respectively), without any significant among-center effect. We conclude that sputum induction can be performed safely in subjects with moderate to severe asthma in multicenter clinical trials when carried out under carefully monitored conditions. Importantly, we demonstrate that measurement of markers of inflammation in induced sputum is as reproducible as methacholine PC(20) and should prove useful in the assessment of airway inflammation in multicenter clinical trials.

Aged↗
PubMed2001

The utility of peak flow, symptom scores, and beta-agonist use as outcome measures in asthma clinical research.

STUDY OBJECTIVES: Several methods of utilizing peak expiratory flow (PEF) and other markers of disease activity have been suggested as useful in the management of asthma. It remains unclear, however, as to which surrogate markers of disease status are discriminative indicators of treatment failure, suitable for use in clinical trials. DESIGN: We analyzed the operating characteristics of 66 surrogate markers of treatment failure using a receiver operating characteristic (ROC) curve analysis. PARTICIPANTS: Information regarding FEV(1), symptoms, beta(2)-agonist use, and PEF was available from 313 subjects previously enrolled in two Asthma Clinical Research Network trials, in which 71 treatment failures occurred (defined by a 20% fall in FEV(1) from baseline). INTERVENTIONS: None. MEASUREMENTS AND RESULTS: None of the measures had an acceptable ability to discriminate subjects with a > or % fall in FEV(1) from those without, regardless of the duration of the period of analysis or the criteria for test positivity employed. Areas under the ROC curves generated ranged from 0.51 to 0.79, but none were statistically superior. Sensitivity and specificity combinations were generally poor at all cutoff values; true-positive rates could not be raised without unacceptably elevating false-positive rates concurrently. CONCLUSIONS: Studies that seek to detect treatment failure defined by a significant fall in FEV(1) should not use such individual surrogate measures to estimate disease severity.

Adolescent↗
PubMed2001

Beta(2)-adrenoceptor polymorphism and body mass index are associated with adult-onset asthma in sedentary but not active women.

STUDY OBJECTIVE: Beta(2)-adrenoceptor Gly16 polymorphism has been associated with asthma severity and beta(2)-adrenoceptor receptor downregulation, but not with the diagnosis of asthma. Glu27 polymorphism may limit beta(2)-adrenoceptor downregulation and predict body mass index (BMI), particularly among sedentary persons. In addition, BMI predicts asthma. We hypothesized that these DNA sequence variants predict adult-onset asthma only in sedentary women. DESIGN: Nested case-control study. SETTING: Nurses' Health Study, a large, prospective cohort study with participants throughout the United States. PARTICIPANTS: Among lifelong nonsmokers, 171 women with adult-onset, medication-requiring asthma and 137 age-matched control subjects. MEASUREMENTS: Physical activity and BMI were self-reported by previously validated questionnaire items. Genomic DNA was obtained from buccal brushings collected via first-class mail. RESULTS: Of 76 sedentary women, the adjusted odds ratios of Gly16 allele were 7.4 (p = 0.047) for asthma and 13.8 (p = 0.02) for steroid-requiring asthma. No similar associations were observed among 232 active women (p = 0.91). Sedentary individuals with both Gly16 and Glu27 alleles had a less elevated risk for asthma. BMI was associated with asthma and Glu27 allele among sedentary women. CONCLUSION: This exploratory analysis suggests an important gene/environment interaction for asthma involving physical activity level. Further study in larger populations is warranted to confirm if sedentary lifestyle unmasks a genetic risk for asthma.

Adult↗
PubMed2000

CC chemokine receptor-2 is not essential for the development of antigen-induced pulmonary eosinophilia and airway hyperresponsiveness.

Monocyte chemoattractant proteins-1 and -5 have been implicated as important mediators of allergic pulmonary inflammation in murine models of asthma. The only identified receptor for these two chemokines to date is the CCR2. To study the role of CCR2 in a murine model of Ag-induced asthma, we compared the pathologic and physiological responses of CCR2(-/-) mice with those of wild-type (WT) littermates following immunization and challenge with OVA. OVA-immunized/OVA-challenged (OVA/OVA) WT and CCR2(-/-) mice developed significant increases in total cells recovered by bronchoalveolar lavage (BAL) compared with their respective OVA-immunized/PBS-challenged (OVA/PBS) control groups. There were no significant differences in BAL cell counts and differentials (i.e., macrophages, PMNs, lymphocytes, and eosinophils) between OVA/OVA WT and CCR2(-/-) mice. Serologic evaluation revealed no significant difference in total IgE and OVA-specific IgE between OVA/OVA WT mice and CCR2(-/-) mice. Lung mRNA expression and BAL cytokine protein levels of IL-4, IL-5, and IFN-gamma were also similar in WT and CCR2(-/-) mice. Finally, OVA/OVA CCR2(-/-) mice developed increased airway hyper-responsiveness to a degree similar to that in WT mice. We conclude that following repeated airway challenges with Ag in sensitized mice, the development of Th2 responses (elevated IgE, pulmonary eosinophilia, and lung cytokine levels of IL-4 and IL5) and the development of airway hyper-responsiveness are not diminished by a deficiency in CCR2.

Animals↗