PubMed Health⌕ Search

Biomedical subjects

Asger Dirksen

Publications and source records attributed to Asger Dirksen.

At least 19 recordsLinked to original sources
PubMed2006

[Centralisation within the field of pulmonary medicine].

In Denmark tuberculosis is rare, with 7.3 cases per 100,000 inhabitants. In regions with few cases, lack of expertise may result in delay in diagnosis, improper treatment, and insufficient contact tracing. We suggest that tuberculosis is dealt with in one centre in each of the five regions in Denmark. LTOT is initiated and controlled by pulmonary specialists in 50% of cases only. Correct indication and follow up is better for patients who received LTOT by pulmonary specialists with a higher patient compliance. We conclude that LTOT should be centralised and treated by pulmonary specialists only.

Antitubercular Agents↗
PubMed2006

Quantitative assessment of emphysema distribution in smokers and patients with alpha1-antitrypsin deficiency.

INTRODUCTION: Identification of upper lobe emphysema is mandatory before lung volume reduction surgery (LVRS). Here we introduce a CT-based objective model for describing the distribution of different types of emphysema. METHODS: Fifty COPD patients were included in the study. Half had alpha1-antitrypsin deficiency (alpha1-COPD) and the rest had smoking-induced emphysema (usual COPD). All patients were scanned 3 times. The relative area of emphysema in each CT slice was plotted against table position, and the cranio-caudal distribution was calculated as the slope of the regression line. RESULTS: The variation in slopes within a patient was much less than the variation in slopes between patients (P<0.0001). There was a significant difference between slopes in the alpha1-COPD and the usual COPD groups (P<0.0001). In the alpha1-COPD group, 24/25 patients had lower lobe emphysema. In the usual COPD group, 4 patients had upper lope predominance, 5 patients had heterogeneous distributions, and 16 patients had lower lobe predominance. CONCLUSIONS: The majority of patients with smoking-related emphysema have a homogeneous distribution and lower lobe predominance although not as noticeable as in alpha1-antitrypsin deficiency. An objective and quantitative method for determining the distribution of emphysema should be applied when selecting candidates for LVRS.

Aged↗
PubMed2006

The capsaicin cough reflex in eczema patients with respiratory symptoms elicited by perfume.

Respiratory symptoms elicited by perfume are common in the population but have unclear pathophysiology. Increased capsaicin cough responsiveness has been associated with the symptoms, but it is unknown whether the site of the symptoms in the airways influences this association. The aim of this study was to investigate the association between the site of airway symptoms elicited by perfume and cough responsiveness to bronchial challenge with capsaicin. 21 eczema patients with respiratory symptoms elicited by perfume were compared with 21 healthy volunteers in a sex- and age-matched case control study. The participants completed a symptom questionnaire and underwent a bronchial challenge with capsaicin. Lower, but not upper, respiratory symptoms elicited by perfume were associated with increased capsaicin cough responsiveness. Having severe symptoms to perfume (n=11) did not relate to the site of the symptoms in the airways and was not associated with increased capsaicin cough responsiveness. In conclusion, respiratory symptoms elicited by perfume may reflect local hyperreactivity related to defensive reflexes in the airways, and measurements of the capsaicin cough reflex are relevant when patients with lower respiratory symptoms related to environmental perfume exposures are investigated.

Adult↗
PubMed2005

Endoscopic ultrasound guided biopsy performed routinely in lung cancer staging spares futile thoracotomies: preliminary results from a randomised clinical trial.

BACKGROUND: Up to 45% of operations with curative intent for non-small-cell lung cancer (NSCLC) can be regarded as futile, apparently because the stage of the disease is more advanced than expected preoperatively. During the past decade several studies have evaluated the usefulness of endoscopic ultrasound guided fine needle aspiration biopsy (EUS-FNA) in lung cancer staging with promising results. However, no randomised trials have been performed, in which a staging strategy with EUS-FNA performed in all patients is compared with a conventional workup. METHODS: Before surgery (i.e. mediastinoscopy and subsequent thoracotomy) 104 patients from one hospital were randomly assigned to either a conventional workup (CWU), including EUS-FNA only for selected patients, or a strategy where all patients were offered EUS-FNA (routine EUS-FNA) in addition to CWU. Patients were followed up for a median period of 1.3 years (range 0.2-2.4 years). Thoracotomy was regarded as futile if the patient had an explorative thoracotomy without tumour resection or if a resected patient had recurrent disease or died from lung cancer during follow-up. Analysis was by intention to treat. RESULTS: Fifty-three patients were randomly assigned to routine EUS-FNA and 51 patients to CWU. EUS-FNA was performed in 50 patients (94%) in the routine EUS-FNA group and in 14 patients (27%) in the CWU group. In the routine EUS-FNA group five patients (9%) had a futile thoracotomy, compared with 13 (25%) in the CWU group, p = 0.03. CONCLUSION: Addition of routine-EUS-FNA to standard workup in routine clinical practice improved selection of surgically curable patients with NSCLC.

Aged↗
PubMed2005

Variability in densitometric assessment of pulmonary emphysema with computed tomography.

OBJECTIVES: The objectives of this study were to investigate whether computed tomography (CT) densitometry can be applied consistently in different centers; and to evaluate the reproducibility of densitometric quantification of emphysema by assessment of different sources of variation, ie, intersite, interscan and inter- and intraobserver variability, in comparison with intersubject variability. MATERIALS AND METHODS: In 5 different hospitals, 119 patients with emphysema were scanned using standardized protocols. In each site, an observer performed a quantitative densitometric analysis (including blood recalibration) on the corresponding patient group (n=23-25) and one observer analyzed the entire group of 119 patients. After several months, the latter observer analyzed all data for a second time. Subsequently, different sources of variation were assessed by variance component analysis with and without volume correction of the data. RESULTS: Inter- and intraobserver variability marginally contributes to the total variability (<0.001%). The interscan variability was 0.02% of the total variation after application of volume correction. The intersite variability was 48% as a result of one deviating CT scanner. Air recalibration normalized deviating air densities in CT scanners. Within sites, the intersubject variability ranged between 93% and 99% based on the analysis of 2 subsequent CT scans of the patients. CONCLUSIONS: Almost all variability in the density measurement of emphysema originates from differences between scanners and from differences in severity of emphysema between patients. Lung densitometry with multislice CT scanners is a highly reproducible measurement, especially if corrected for lung volume, because this reduces interscan variability.

Absorptiometry, Photon↗
PubMed2004

Endoscopic ultrasound guided biopsy versus mediastinoscopy for analysis of paratracheal and subcarinal lymph nodes in lung cancer staging.

BACKGROUND: Exact mediastinal evaluation of patients with non-small-cell lung cancer (NSCLC) is mandatory to improve selection of resectable and curable patients for surgery. Mediastinoscopy (MS) and endoscopic ultrasound guided fine needle aspiration biopsy (EUS-FNA) are considered complementary, MS covering the anterior- and EUS-FNA the posterior mediastinum. Both methods can reach the paratracheal- and subcarinal-regions, but little is known about which method is most accurate, when compared in patients having both procedures performed. The aim of this study was to assess and compare the diagnostic value of MS and EUS-FNA with regard to mediastinal malignancy in the paratracheal- and subcarinal-regions. METHODS: Sixty patients considered to be potential candidates for resection of verified or suspected NSCLC underwent MS and EUS-FNA. The EUS-FNA diagnoses were confirmed either by open thoracotomy, MS or clinical follow-up. RESULTS: MS and EUS-FNA were conclusive for paratracheal or subcarinal mediastinal disease in 6 and 24 patients, respectively. Two patients with N2 disease diagnosed by EUS-FNA were upstaged to N3 by MS. The sensitivity for lymph node metastases in the right paratracheal region (2/4R) was 67% for EUS-FNA versus 33% for MS (p=0.69). In the left paratracheal region (2/4L) the sensitivity of EUS-FNA was 80% versus 33% for MS (p=0.06). In the subcarinal region (7) the sensitivity of EUS-FNA was 100% versus 7% for MS (p<0.01). The sensitivity for lymph node metastases in region 2/4L and/or 2/4R and/or 7 was 96% for EUS-FNA versus 24% for MS (p<0.01). CONCLUSION: In our hands EUS-FNA was superior to MS in the examination of paratracheal- and subcarinal-regions of patients considered for resection of lung cancer.

Aged↗
PubMed2004

Hyperpolarized 3He MRI and 81mKr SPECT in chronic obstructive pulmonary disease.

PURPOSE: During recent years, magnetic resonance imaging (MRI) using hyperpolarised (HP) 3He gas has emerged as a promising new method for the imaging of lung ventilation. However, systematic comparisons with nuclear medicine techniques have not yet been performed. The aim of this study was to compare ventilation imaging methods in 26 patients with chronic obstructive pulmonary disease (COPD) and nine lung healthy volunteers. METHODS: HP 3He MRI, 81mKr single-photon emission computed tomography (SPECT), high-resolution computed tomography (HRCT) and pulmonary function tests were performed. The three scans were scored visually as percentage of non-ventilated/diseased lung, and a computer-based objective measure of the ventilated volume in HP 3He MRI and 81mKr SPECT and an emphysema index in HRCT were calculated. RESULTS: We found a good correlation between HP 3He MRI and 81mKr SPECT for both visual defect score (r=0.80, p<0.0001) and objective estimate of ventilation (r=0.45, p=0.0157). In addition, both scans were well correlated with reference methods for the diagnosis of emphysema (pulmonary function test and HRCT). The defect scores were largest on 81mKr SPECT (the score on HP 3He MRI was one-third less than that on 81mKr SPECT), but the difference was reduced after normalisation for different breathing depths (HP 3He MRI at total lung capacity; 81mKr SPECT at tidal breathing at functional residual capacity). CONCLUSION: HP 3He MRI provides detailed ventilation distribution images and defect scores are comparable on HP 3He MRI and 81mKr SPECT. Additionally, new insights into the regional pulmonary microstructure via the apparent diffusion coefficient measurements are provided by HP 3He MRI. HP 3He MRI is a promising new diagnostic tool for the assessment of ventilation distribution.

Administration, Inhalation↗
PubMed2004

Comparison of the sensitivities of 5 different computed tomography scanners for the assessment of the progression of pulmonary emphysema: a phantom study.

RATIONALE AND OBJECTIVES: To compare the sensitivities of 5 different computed tomography scanners (4 multislice CT [MSCT] and 1 single-slice CT) in the assessment of the progression of pulmonary emphysema. METHODS: A Perspex cylinder phantom was constructed containing small pieces of polythene foam with densities representative of lung. Changing the cylinder's volume simulated subtle lung density changes. The sensitivity to density changes was defined by the variation in the residual errors from the linear regression line between time and density. RESULTS: The single-slice CT scanner was significantly less sensitive to density changes than MSCT scanners. Also, among MSCT scanners, small but significant differences were found when the standardized acquisition protocol was used. CONCLUSIONS: Considering the large sensitivity differences between single- and multislice CT scanners, we would recommended using MSCT scanners in clinical multicenter trials in emphysema. The protocol standardization of MSCT scanners can still be further improved.

Humans↗
PubMed2003

Stability of DNA patterns and evidence of Mycobacterium tuberculosis reactivation occurring decades after the initial infection.

Two hundred three freeze-dried strains of Mycobacterium tuberculosis collected during the 1960s were compared with 4102 strains collected during the 1990s, and 14 DNA patterns identified among the "historical strains" were 100% identical to patterns identified among the "recent strains." They were isolated from 41 and 40 patients who had tuberculosis during the 1960s and 1990s, respectively. The patients' mean age differed by >30 years, a finding strongly suggesting that the patients from the 1990s experienced reactivation of M. tuberculosis infection acquired during the 1960s. The half-life of IS6110 DNA patterns during latency was estimated to be 36 years (95% confidence interval, 25-54 years). Thus, this comparison of historical and recent strains yields molecular epidemiologic evidence of M. tuberculosis reactivation spanning decades and suggests that the rate of change of DNA patterns during latency is much longer than that during active disease. This has important implications for the interpretation of clustering, especially for the extent of recent transmission.

Adult↗
PubMed2003

IgG antibodies against microorganisms and atopic disease in Danish adults: the Copenhagen Allergy Study.

BACKGROUND: Seropositivity to food-borne and orofecal microorganisms (hepatitis A virus, Helicobacter pylori, and Toxoplasma gondii ), which are considered to be markers of poor hygiene, has been reported to be associated with a lower prevalence of atopy. In contrast, colonization of the gut with Clostridium difficile, a potential intestinal bacterial pathogen, in early childhood may be associated with a higher prevalence of atopy. OBJECTIVE: The objective of this study was to investigate the association between atopy and exposure to 2 groups of food-borne and orofecal microorganisms: (1) markers of a poor hygiene and (2) intestinal bacterial pathogens. METHODS: A cross-sectional population-based study of 15- to 69-year-olds living in Copenhagen, Denmark, was carried out in 1990 to 1991. Atopy was defined as a positive test result for specific IgE to at least 1 of 6 inhalant allergens. Exposure to microorganisms was assessed as IgG seropositivity to microorganisms. RESULTS: Seropositivity to 2 or 3 markers of poor hygiene (hepatitis A virus, H pylori, and T gondii ) was associated with a lower prevalence of atopy (adjusted odds ratio, 0.5; 95% CI, 0.3 to 0.8). In contrast, seropositivity to 2 or 3 intestinal bacterial pathogens (C difficile, Campylobacter jejuni, and Yersinia enterocolitica ) was associated with a higher prevalence of atopy (adjusted odds ratio, 1.7; 95% CI, 1.2 to 2.6). CONCLUSION: Exposure to markers of poor hygiene was associated with a lower prevalence of atopy, whereas exposure to intestinal bacterial pathogens was associated with a higher prevalence of atopy. These findings raise the hypothesis that different groups of food-borne and orofecal microorganisms may have different effects on the risk of atopy.

Adolescent↗
PubMed2003

Mycobacterium tuberculosis Beijing genotype.

Molecular epidemiologic studies of strains of Mycobacterium tuberculosis are currently conducted worldwide. The genetically distinct Beijing family of strains has been associated with large outbreaks of tuberculosis, increased virulence, and multidrug resistance. However, in this first population-based search for Beijing strains in the Danish DNA fingerprint database, analysis of 97% of all culture-positive tuberculosis patients in 1992 to 2001 showed that 2.5% of 3,844 patients, 1.0% of Danish-born patients, and 3.6% of immigrants (from 85 countries) had Beijing strains. No Beijing strains were found among 201 strains from Danish-born patients sampled in the 1960s, and no evidence of an increase in Beijing strains was found over time. The true prevalence of Beijing strains worldwide is unknown because only a fraction of global strains have been analyzed.

Adult↗
PubMed2002

[Increasing prevalence of specific IgE against aeroallergens in an adult Danish population--two cross-sectional studies in 1990 and 1998].

BACKGROUND: There is evidence that the prevalence of respiratory allergy has increased in children in many countries. However, this evidence is largely based on questionnaire data, and little is known about similar trends in adults. We investigated whether the prevalence of specific IgE to aeroallergens had increased in an adult general population over an 8-year period. MATERIAL AND METHODS: Two cross-sectional surveys were carried out in 1990 and 1998. A screening questionnaire on respiratory symptoms sent to random samples of 15-41-year-old subjects living in Copenhagen (Denmark) preceded both surveys. Random samples of responders were invited to a health examination, which included assessment of specific IgE to six common aeroallergens. Totals of 312 (74.6% of those invited) and 482 (53.4% of those invited) subjects were examined in 1990 and 1998, respectively. Serum samples from both surveys were analysed in 1999. RESULTS: The prevalence of specific IgE to at least one allergen increased significantly from 1990 to 1998 (26.5% versus 33.9%; odds ratio adjusted for sex, age, and season of examination, 1.63; 95% confidence interval, 1.15-2.32). This increase remained unexplained after adjustment for changes in questionnaire variables on life-style and home environment. The clinical significance of this increase was underlined by a corresponding increase in the prevalence of allergic rhinitis symptoms associated with specific IgE positivity. DISCUSSION: We found that the prevalence of specific IgE positivity to aeroallergens increased in an adult Danish general population from 1990 and 1998.

Adolescent↗
PubMed2002

Molecular evidence of endogenous reactivation of Mycobacterium tuberculosis after 33 years of latent infection.

Since Robert Koch described the cause of tuberculosis in 1882, the natural history of the disease after primary infection has been subject to debate. Only approximately 10% of infected individuals develop active disease, which may appear years to decades after infection. Late onset has been attributed to the endogenous reactivation of dormant bacteria. However, this has not been documented by molecular means for latencies of more than a few years. In Denmark, we have recently recultured 205 freeze-dried Mycobacterium tuberculosis strains obtained from 1961 through 1967. These "historical" strains are analyzed by DNA restriction fragment-length polymorphism testing, and their DNA patterns are compared with those of 4008 recently obtained clinical specimens. This has, surprisingly, yielded molecular evidence of M. tuberculosis reactivation after 33 years of latent infection. A father and son who developed tuberculosis in 1961 and in 1994, respectively, were the only patients infected with strains that share an identical DNA pattern.

Adult↗