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Biomedical subjects

R Dahl

Publications and source records attributed to R Dahl.

At least 19 recordsLinked to original sources
PubMed2001

Inhaled formoterol dry powder versus ipratropium bromide in chronic obstructive pulmonary disease.

We compared the effectiveness of inhaled formoterol with that of ipratropium in the treatment of chronic obstructive pulmonary disease (COPD). After a 2-wk run-in period, 780 patients with COPD were randomized to receive for 12 wk formoterol dry powder 12 or 24 microg twice daily, ipratropium bromide 40 microg four times daily, or placebo in a multicenter, double-blind, parallel-group study. The primary efficacy variable was the area under the curve for forced expiratory volume in 1 s (FEV(1)) measured over 12 h after 12 wk of treatment. Secondary variables included diary symptoms and quality of life. Both doses of formoterol and ipratropium significantly increased the area under the curve for FEV(1) in comparison with placebo (all p < 0.001). Both doses of formoterol were also significantly superior to ipratropium (all p < 0.025). Compared with placebo, both doses of formoterol significantly improved symptoms (all p < or = 0.007) and quality of life (p < 0.01 for total scores) whereas ipratropium did not show significant effects (all p > or = 0.3). All study treatments exhibited a similar safety profile. We conclude that formoterol is more effective than ipratropium bromide in the treatment of COPD, as the efficacy of ipratropium on airflow obstruction does not translate into a clinical benefit that patients can perceive.

Administration, Inhalation↗
PubMed2001

Identification of three new splice variants of the SNARE protein SNAP-23.

SNAP-23 has an important role in protein-trafficking processes in mammalian cells and until yet two isoforms of SNAP-23 (SNAP-23a and SNAP-23b) have been described. In the present report, we have identified the existence of three new SNAP-23 isoforms (named SNAP-23c, SNAP-23d, and SNAP-23e), which arise from alternative splicing. By RT-PCR all five splice variants were shown to be expressed in four different human inflammatory cells (eosinophils, basophils, neutrophils, and peripheral blood mononuclear cells). Transfection of the human basophilic KU-812 cell line with plasmid constructs containing the cDNAs of the five splice variants located SNAP-23a and SNAP-23b primarily in the plasma membrane. The other three splice variants were localized both intracellularly and in the plasma membrane.

Alternative Splicing↗
PubMed2001

PU.1 exhibits partial functional redundancy with Spi-B, but not with Ets-1 or Elf-1.

Previously it was shown that the Ets proteins, PU.1 and Spi-B, exhibit functional redundancy in B lymphocytes. To investigate the possibility that PU.1 or Spi-B or both share overlapping roles with Ets-1 or Elf-1, PU.1(+/-)Ets-1(-/-), PU.1(+/-)Elf-1(-/-), and Spi-B(-/-)Ets-1(-/-) animals were generated. No blood cell defects were observed in these animals except those previously reported for Ets-1(-/-) mice. Therefore, no genetic overlap was detected between PU.1 or Spi-B with Ets-1 or Elf-1. In contrast, the results confirmed functional redundancy for PU.1 and Spi-B in that PU.1(+/-)Spi-B(-/-) bone marrow progenitors yielded smaller colonies in methylcellulose cultures than did wild-type, PU.1(+/-) or Spi-B(-/-) progenitors. In addition, PU.1(+/-)Spi-B(+/+), PU.1(+/-)Spi-B(+/-), and PU.1(+/-) Spi-B(-/-) mice displayed extramedullary splenic hematopoiesis. In summary, PU.1 and Spi-B regulate common target genes required for proliferation of hematopoietic progenitors or their committed descendants, whereas Ets-1 or Elf-1 do not appear to regulate shared target genes with PU.1 or Spi-B.

Animals↗
PubMed2001

SNARE proteins are critical for regulated exocytosis of ECP from human eosinophils.

The SNARE hypothesis, describing a protein assembly-disassembly pathway, was recently proposed for the sequential steps of synaptic vesicle docking, activation, and fusion. To determine if SNARE proteins are involved in regulated exocytosis in eosinophils, the presence and functional role of SNAREs was examined in human blood eosinophils. Immunoblotting, subcellular fractionation, and immunocytochemistry documented that vesicle-associated membrane protein-2 (VAMP-2), a vesicle-SNARE, was expressed in human eosinophils. Syntaxin 4 and SNAP-25 were also detected. Sequencing of cloned RT-PCR products amplified from a domain conserved among VAMP isoforms revealed identity only to VAMP-2 but not to VAMP-1 or cellubrevin. Functional experiments revealed that tetanus toxin pretreatment, which cleaved VAMP-2 in eosinophils, significantly inhibited both IgE receptor- and phorbol ester-mediated exocytosis of eosinophil cationic protein (ECP) from streptolysin-O-permeabilized eosinophils. Thus, these results strongly suggest a critical role of SNAREs in regulated exocytosis in eosinophils.

Animals↗
PubMed2001

SNARE proteins are critical for regulated exocytosis of ECP from human eosinophils.

The SNARE hypothesis, describing a protein assembly-disassembly pathway, was recently proposed for the sequential steps of synaptic vesicle docking, activation and fusion. To determine if SNARE proteins are involved in regulated exocytosis in eosinophils, the presence and functional role of SNAREs was examined in human blood eosinophils. Immunoblotting, subcellular fractionation, and immunocytochemistry documented that vesicle-associated membrane protein-2 (VAMP-2), a vesicle-SNARE, was expressed in human eosinophils. Syntaxin 4 and SNAP-25 were also detected. Sequencing of cloned RT-PCR products amplified from a domain conserved among VAMP isoforms revealed identity only to VAMP-2 but not to VAMP-1 or cellubrevin. Functional experiments revealed that tetanus toxin pretreatment, which cleaved VAMP-2 in eosinophils, significantly inhibited both IgE receptor- and phorbol ester-mediated exocytosis of eosinophil cationic protein (ECP) from streptolysin-O-permeabilized eosinophils. Thus, these results strongly suggest a critical role of SNAREs in regulated exocytosis in eosinophils.

Amino Acid Sequence↗
PubMed2001

No linkage and association of atopy to chromosome 16 including the interleukin-4 receptor gene.

BACKGROUND: Several susceptibility genes for atopy have been suggested in recent years. Few have been investigated as intensively as the interleukin-4-receptor alpha (IL4Ralpha) gene on chromosome 16. The results remain in dispute. Therefore, in a robust design, we tested for association of type I allergy to the IL4R variations I50V and Q576R, and investigated chromosome 16 for atopy candidate regions in general. METHODS: We identified 100 Danish allergy sib-pair families. Five conservative phenotypes for type I allergy were defined and evaluated. The IL4R variations were genotyped in trios and evaluated by the transmission disequilibrium test (TDT). Multipoint linkage analysis and exclusion mapping were conducted with sib-pairs analyzed for 17 microsatellite markers. RESULTS: No evidence for association or linkage to the IL4R polymorphisms was found (P values: 0.12-0.90). Linkage analysis did not support linkage of any of the phenotypes to chromosome 16. Major parts of chromosome 16 were excluded as candidate regions harboring oligogenes for type I allergy. CONCLUSION: We found chromosome 16 unlikely to harbor strong candidate genes for type I allergy. The role of the IL4Ralpha gene in the inheritance of atopy was insignificant in the Danish population. The use of conservative allergy phenotypes in the search for genes predisposing to atopic disease was discussed.

Child↗
PubMed2001

Bile acid-induced rat hepatocyte apoptosis is inhibited by antioxidants and blockers of the mitochondrial permeability transition.

The accumulation of hydrophobic bile acids plays a role in the induction of apoptosis and necrosis of hepatocytes during cholestasis. The aim of this study was to determine in freshly isolated rat hepatocytes the roles of oxidant stress and the mitochondrial permeability transition (MPT) in bile acid-induced apoptosis. Hepatocytes isolated from adult male Sprague-Dawley rats were incubated for 4 hours in buffer containing the hydrophobic bile acid, glycochenodeoxycholic acid (GCDC, 0-500 micromol/L) or the hydrophilic bile acid, glycocholic acid (GCA), and either the antioxidants, alpha tocopherol, ebselen, or idebenone (a coenzyme Q analogue); or the MPT blockers, cyclosporin A, or bongkrekic acid, or a caspase-8 inhibitor. Apoptosis was assessed hourly by nuclear morphologic changes of fixed cells by DAPI fluorescence microscopy and reactive oxygen species (ROS) generation by dichlorofluorescein fluorescence of hepatocytes. The percent of cells undergoing apoptosis increased in a time- and concentration-dependent manner in cells exposed to GCDC, and to a much lesser extent to GCA. ROS generation preceded the onset of apoptosis. MPT blockers, caspase-8 inhibition, and antioxidants prevented apoptosis and reduced ROS generation by hepatocytes. Flow cytometry analysis showed that MPT occurred within 1 hour of exposure of cells to 100 micromol/L GCDC, prior to onset of significant apoptosis. In conclusion, ROS generation, MPT induction, and cytochrome c release are critical steps in the induction of apoptosis by bile acids. Antioxidants may reduce liver injury caused by low levels of bile acids by preventing the generation of oxidant stress and subsequent stimulation of the MPT and release of cytochrome c from mitochondria.

Animals↗
PubMed2001

Mode of action of intranasal corticosteroids.

The mode of action of intranasal corticosteroids (INCS) is complex. It is not known whether INCS penetrate the nasal mucosa or act on target cells; however, their low systemic activity supports the concept of local action on nasal mucosa. This local effect can nonetheless influence a variety of inflammatory cells and their mediators such as epithelial cells, lymphocytes, basophils, mast cells, and Langerhans cells. Corticosteroid-induced inhibition of immunoglobulin E-dependent release of histamine is a possible but unproven mode of action. Epithelial cells are an important target for corticosteroids, and INCS concentration is high at the epithelial surface. INCS may combine with the corticosteroid receptors in epithelial cells, which are then expelled into the airway lumen together with the dead epithelial cells or migrating inflammatory cells. A reduced influx of mediator cells may explain some of the effects of INCS on rhinitis symptoms, but it cannot explain all of the effects because INCS also reduce the early-phase sneezing and rhinorrhea after an allergen challenge outside the pollen season. In this situation, the number of surface mast cells/basophils is very low, as it is in the absence of allergic rhinitis. The mechanism by which INCS treatment of allergic rhinitis reduces itching, sneezing, and rhinorrhea, the characteristic symptoms of an early-phase response involving mast cell release of histamine, remains to be determined. Studies should be conducted to characterize the broad range of mechanisms by which INCS produce their therapeutic effects in allergic rhinitis.

Administration, Intranasal↗
PubMed2001

SNAP-25-associated Hrs-2 protein colocalizes with AQP2 in rat kidney collecting duct principal cells.

The vasopressin-induced trafficking of aquaporin-2 (AQP2) water channels in kidney collecting duct is likely mediated by vesicle-targeting proteins (N-ethylmaleimide-sensitive factor attachment protein receptors). Hrs-2 is an ATPase believed to have a modulatory role in regulated exocytosis. To examine whether Hrs-2 is expressed in rat kidney, we carried out RT-PCR combined with DNA sequence analysis and Northern blotting using a digoxigenin-labeled Hrs-2 RNA probe. RT-PCR and Northern blotting revealed that Hrs-2 mRNA is localized in all zones of rat kidney. The presence of Hrs-2 protein in rat kidney was confirmed by immunoblotting, revealing a 115-kDa protein in kidney and brain membrane fractions corresponding to the expected molecular size of Hrs-2. Immunostaining and confocal laser scanning microscopy of LLC-PK(1) cells (a porcine proximal tubule cell line) transfected with Hrs-2 DNA confirmed the specificity of the antibody and revealed that Hrs-2 is mainly localized in intracellular compartments, including cathepsin D-containing lysosomal/endosomal compartments. The cellular and subcellular localization of Hrs-2 in rat kidney was examined by immunocytochemistry and confocal laser scanning microscopy. Hrs-2 immunoreactivity was observed in collecting duct principal cells, and weaker labeling was detected in other nephron segments. The labeling was predominantly present in intracellular vesicles, but labeling was also observed in the apical plasma membrane domains of some cells. Colabeling with AQP2 revealed colocalization in vesicles and apical plasma membrane domains, suggesting a role for Hrs-2 in regulated AQP2 trafficking.

Adenosine Triphosphatases↗
PubMed2001

Herpesvirus type 1-8 in BAL fluid from HIV-1-infected patients with suspected pneumonia and from healthy individuals.

Pneumonia is still a major problem in human immunodeficiency virus (HIV)-infected patients, and despite extensive investigation the aetiology remains unknown in many cases. The prevalence of the eight human herpesviruses was determined by polymerase chain reaction in 91 samples of bronchoalveolar lavage (BAL) fluid from 72 HIV-infected patients with 91 episodes of suspected pneumonia. The presence of herpesviruses was related to clinical and immunological findings and the prevalence of herpesviruses in HIV-infected patients was compared with the prevalence in BAL fluid from 50 healthy, immunocompetent individuals. Epstein-Barr virus, cytomegalovirus and human herpesvirus-8 (HHV8) were found in 5.5%, 36% and 5.5% of BAL fluid samples from HIV-infected patients. No herpesviruses were detectable in BAL fluid from healthy, immunocompetent individuals. The herpesviruses occurred mainly in patients with CD4+ counts <200 x 10(6) L(-1). All patients with herpesviruses recovered without specific antiviral treatment. Two patients with HHV8 had the diagnosis of Kaposi's sarcoma. It is concluded that cytomegalovirus, Epstein-Barr virus, and human herpesvirus-8 are frequently present in bronchoalveolar lavage fluid from severely immunocompromised human immunodeficiency virus-infected patients with pulmonary symptoms. In bronchoalveolar lavage fluid from healthy, immunocompetent individuals, herpesviruses are absent. Apart from human herpesvirus-8, the present results indicate that the herpesviruses do not play a serious pathogenic role in the development of pulmonary symptoms in human immunodeficiency virus-infected patients.

AIDS-Related Opportunistic Infections↗
PubMed2001

Role of oxidant stress in the permeability transition induced in rat hepatic mitochondria by hydrophobic bile acids.

Hydrophobic bile acids may cause hepatocellular necrosis and apoptosis during cholestatic liver diseases. The mechanism for this injury may involve mitochondrial dysfunction and the generation of oxidant stress. The purpose of this study was to determine the relationship of oxidant stress and the mitochondrial membrane permeability transition (MMPT) in hepatocyte necrosis induced by bile acids. The MMPT was measured spectrophotometrically and morphologically in rat liver mitochondria exposed to glycochenodeoxycholic acid (GCDC). Freshly isolated rat hepatocytes were exposed to GCDC and hepatocellular necrosis was assessed by lactate dehydrogenase release, hydroperoxide generation by dichlorofluorescein fluorescence, and the MMPT in cells by JC1 and tetramethylrhodamine methylester fluorescence on flow cytometry. GCDC induced the MMPT in a dose- and Ca(2+)-dependent manner. Antioxidants significantly inhibited the GCDC-induced MMPT and the generation of hydroperoxides in isolated mitochondria. Other detergents failed to induce the MMPT and a calpain-like protease inhibitor had no effect on the GCDC-induced MMPT. In isolated rat hepatocytes, GCDC induced the MMPT, which was inhibited by antioxidants. Blocking the MMPT in hepatocytes reduced hepatocyte necrosis and oxidant stress caused by GCDC. Oxidant stress, and not detergent effects or the stimulation of calpain-like proteases, mediates the GCDC-induced MMPT in hepatocytes. We propose that reducing mitochondrial generation of reactive oxygen species or preventing increases in mitochondrial Ca(2+) may protect the hepatocyte against bile acid-induced necrosis.

Animals↗
PubMed2001

Pending resolution: the question of who owns DNA.

With the emergence of the Human Genome Project and its private counterparts, the U.S. Patent and Trademark Office has begun receiving applications for the patenting of genes and genetic sequences. Earlier patent decisions regarding similar scientific advances limited patents to organisms "made by the hand of man," which would seem to remove discovered genes from patent protection. But many applicants have been successful in attaining patents for genes based on their ability to demonstrate the ultimate utility of the gene, for instance in medicine. One controversy regarding genomic patenting, however, is that patents apparently have been granted for mere gene fragments devoid of much demonstrable utility. Furthermore, critics fear that gene patenting will retard research by squelching scientists' ability to share findings freely.

Biotechnology↗
PubMed2001

Intranasal corticosteroids for allergic rhinitis: superior relief?

Whether first-line pharmacological treatment of allergic rhinitis should be antihistamines or intranasal corticosteroids has been discussed for several years. First-generation antihistamines are rarely used in the treatment of allergic rhinitis, mainly because of sedative and anticholinergic adverse effects. On the basis of clinical evidence of efficacy, no second-generation antihistamine seems preferable to another. Similarly, comparisons of topical and oral antihistamines have been unable to demonstrate superior efficacy for one method of administration over the other. Current data documents no striking differences in efficacy and safety parameters between intranasal corticosteroids. When the efficacy of antihistamines and intranasal corticosteroids are compared in patients with allergic rhinitis, present data favours intranasal corticosteroids. Interestingly, data do not show antihistamines as superior for the treatment of conjunctivitis. Safety data from comparative studies in patients with allergic rhinitis do not indicate differences between antihistamines and intranasal corticosteroids. Combining antihistamines and intranasal corticosteroids in the treatment of allergic rhinitis does not provide any additional effect to intranasal corticosteroids alone. On the basis of current data, intranasal corticosteroids seem to offer superior relief in allergic rhinitis than antihistamines.

Administration, Inhalation↗
PubMed2001

Extrafine beclomethasone dipropionate breath-actuated inhaler (400 micrograms/day) versus budesonide dry powder inhaler (800 micrograms/day) in asthma.

Hydrofluoroalkane-134a beclomethasone dipropionate extrafine aerosol breath-actuated inhaler (Qvar Autohaler; BDP-AH) provides an alternative to chlorofluorocarbon metered dose inhalers or dry powder inhalers (DPIs). The aim of this six-week, open-label study was to determine whether BDP-AH demonstrates equivalent asthma control to twice the dose of budesonide (BUD)-DPI (Pulmicort Turbuhaler). Adults with symptomatic asthma inadequately controlled on BUD-DPI 400 micrograms/day and beta-agonist were enrolled. Patients (n = 193) were randomised to receive 400 micrograms/day BDP-AH (n = 98) (two puffs of 100 micrograms/actuation inhaler twice daily) or 800 micrograms/day BUD-DPI (n = 95) (two puffs of 200 micrograms/actuation inhaler twice daily). Both groups showed a statistically significant change from baseline in morning (a.m.) peak expiratory flow (PEF) at weeks 5-6 (p < 0.01), indicating study treatment improved a.m. PEF over prestudy 400 micrograms/day BUD. Changes from baseline in a.m. PEF at weeks 5-6 were 15.9 l/min for BDP-AH and 14.2 l/min for BUD-DPI; the groups were statistically equivalent (90% CI -7.02-10.44; p < -0.001 [equivalence = within +/- 25 l/min]). Other efficacy assessments (evening PEF, FEV1, asthma symptoms, beta-agonist use) confirmed the treatments were clinically equivalent. Thirty-nine (40%) patients on BDP-AH and 35 (37%) on BUD-DPI experienced at least one adverse event (p = 0.767). Four (4%) patients on BDP-AH and 3 (3%) on BUD-DPI reported increased asthma symptoms. BDP-AH at half the daily dose provided equivalent asthma control to BUD-DPI; both treatments were well tolerated.

Administration, Inhalation↗
PubMed2000

The effect of long-acting beta2-agonists on airway inflammation in asthmatic patients.

Early observations suggested that the inhibition by long-acting beta2-agonists (LABAs) of non-specific bronchial hyperresponsiveness following allergen challenge was unrelated to bronchodilation or functional antagonism and might be a reflection of anti-inflammatory activity. Investigation of the effect of LABAs on airway inflammatory responses has demonstrated an inhibition of eosinophil recruitment in allergen challenge studies. Nevertheless, results from biopsy and other studies suggest that the chronic inflammatory process in asthma patients is unaffected by these drugs. There is no evidence from biopsy studies that LABAs are pro-inflammatory or that they mask existing inflammation. The beneficial effects of LABAs in allergen challenge are probably mediated through stabilization of mast cells. Recent evidence suggests that LABAs may reduce numbers of neutrophils and their associated markers; this observation needs to be confirmed in future studies and its relevance to the treatment of asthma determined.

Adrenergic beta-Agonists↗