Biomedical subjects

Thomas Halvorsen

Publications and source records attributed to Thomas Halvorsen.

8 recordsLinked to original sources

PubMed2007

Surgical treatment of exercise-induced laryngeal dysfunction.

A method for combined ergo-spirometry and continuous laryngeal inspection during exercise, entitled continuous laryngoscopy exercise test (CLE-test) has been developed in order to study airway obstruction at the laryngeal level during exercise. The aim of the study was to apply the CLE-test on patients experiencing respiratory distress during exercise in order to reveal the usefulness of the CLE-test both as a diagnostic tool in the selection of patients for surgery and in evaluation of treatment effects postoperatively. Until now, 81 patients with a history of exercise-induced stridor have undergone the CLE-test. Ten of these patients were selected for surgical treatment based on the severity of symptoms and their motivation for treatment. All ten patients underwent endoscopic supraglottoplasty (ES), with laser incision in both aryepiglottic folds anterior to the cuneiform cartilages and removal of the mucosa around the top of the tubercles. Each patient was examined by the CLE-test before and 3 months after surgery. Eight patients felt subjectively that their breathing capacity during exercise was improved. When pre- and postoperative ergo-spirometry evaluations were compared, increased peak oxygen consumption was observed in four out of ten patients and better maximal minute ventilation in seven out of ten. Postoperative evaluation of the laryngeal images showed less prominent aryepiglottic folds. The typical adduction of the supraglottic structures concomitant with inspiratory stridor found preoperatively was not present in any of the patients during exercise postoperatively. The ES procedure is an efficient surgical treatment for exercise-induced laryngeal supraglottic obstruction and the CLE-test eases the selection of patients for surgery and facilitates the evaluation of treatment effects.

Adolescent↗

PubMed2006

Better care of immature infants; has it influenced long-term pulmonary outcome?

AIMS: To assess whether lung function in late childhood had improved in subjects born extremely prematurely in the early 1990s compared to the early 1980s, and whether neonatal factors in the respective periods had different impact on long-term pulmonary outcome. DESIGN: Population-based, controlled cohort study. Lung function was determined in 81 of 86 (94%) eligible subjects born with gestational age < or =28 weeks or birthweight < or =1000 g in Western Norway in 1982-85 (n=46) and 1991-92 (n=35), and in 81 matched control subjects born at term. RESULTS: The incidence of bronchopulmonary dysplasia was similar in the two periods. At follow-up, airway obstruction, hyper-responsiveness and pulmonary hyperinflation were similarly increased in both preterm cohorts compared to matched controls. Furthermore, current lung function was similarly related to neonatal respiratory disease in both birth-cohorts: FEV1 was reduced with respectively 18.6% and 18.7% of predicted in preterms dependent on supplemental oxygen at 36 weeks postmenstrual age. Lack of antenatal treatment with corticosteroids and prolonged neonatal oxygen treatment predicted similar significant airway obstruction in the two birth-cohorts. CONCLUSION: Preterms born in different eras of neonatology had similar long-term decreases in lung function. Long periods of oxygen supplementation are still required to salvage immature infants, and airway obstruction may still be a common long-term outcome.

Adolescent↗

PubMed2006

Continuous laryngoscopy exercise test: a method for visualizing laryngeal dysfunction during exercise.

OBJECTIVES/HYPOTHESIS: To assess the diagnostic feasibility and patient acceptance of a new developed diagnostic test for exercise induced upper airway flow limitation. STUDY DESIGN: Clinical case control study including evaluation of contemporary ergo-spirometry and laryngoscopy continuously performed during exercise. METHODS: Twelve nonsymptomatic controls and four young females with documented dyspnea and noisy breathing during exercise were studied. All subjects exercised to exhaustion on a treadmill while attached to a fully equipped ergo-spirometry unit and a fiberoptic laryngoscope linked to a video camera and a sound recorder. RESULTS: The test situation was well tolerated. Two control subjects had a minor inspiratory synchronous medial motion of the aryepiglottic folds without limitation of laryngeal airflow. In the four symptomatic subjects, exercise induced inspiratory synchronous medial motion of the dorsal part of the aryepiglottic folds as well as vocal cord adduction and inspiratory stridor was demonstrated. CONCLUSION: The continuous laryngoscopy exercise test was easy to perform, well tolerated, and can be implemented in future diagnostic work-up programs of laryngeal dysfunction.

Adolescent↗

PubMed2006

Mast cell activation and leukotriene secretion in wheezing infants. Relation to respiratory syncytial virus and outcome.

The persistence of wheezing after early wheezing episodes in infancy may be related to the virus involved and to the type of inflammation during the initial wheezing. The role of mast cell activation and leukotriene secretion in wheezing, and the relation to outcome, is not known. Our objective was to study markers of mast cell activation and leukotriene secretion from wheezing infants, and the relation to respiratory syncytial virus (RSV) infection and persistent wheezing. Urinary 9alpha,11beta-PGF(2), a marker of mast cell activation, and urinary leukotriene E4 were measured in 106 infants hospitalized for wheezing during their first year of life. Results were related to the presence of RSV infection and the persistence of wheezing at follow-up 20 months later. Levels of 9alpha,11beta-PGF(2) were higher in infants positive for RSV than in those with RSV negative wheezing, but both groups had higher levels than controls. Leukotriene E4 levels were higher in wheezing infants than in controls. Urinary 9alpha,11beta-PGF(2) levels were higher in infants with transient compared with persistent wheezing. We found a positive correlation between 9alpha,11beta-PGF(2) and leukotriene E4, strongest in infants with RSV negative disease and in infants with persistent wheezing. The results suggest that mast cells play an important role in infant wheezing, and may be a major source of leukotriene secretion in these infants. Mast cell activation and leukotriene secretion were not associated with persistent wheezing.

Eosinophil-Derived Neurotoxin↗

PubMed2006

High-resolution CT of the chest in children and young adults who were born prematurely: findings in a population-based study.

OBJECTIVE: The purpose of this study was to use a scoring system for high-resolution CT in the evaluation of radiologic findings in young people born extremely preterm and to examine the reproducibility of this scoring system. SUBJECTS AND METHODS: High-resolution CT of the lungs was assessed in 72 children born at a gestational age of < or = 28 weeks or with a birth weight of < or = 1,000 g within a defined region in western Norway in 1982-1985 (n = 40) or in 1991-1992 (n = 32). All images were analyzed by two pediatric radiologists using a scoring system in which a total of 14 features were assessed. RESULTS: Sixty-three (88%) of the subjects had abnormal findings, the most common being linear opacities (n = 52), triangular opacities (n = 42), air trapping (n = 19), and mosaic perfusion (n = 10). Right and left lungs were equally affected. There were fewer abnormalities in the younger age group (born in 1991-1992). Intraobserver agreement and interobserver agreement were moderate (weighted kappa = 0.54 and kappa = 0.52, respectively). Fifty-six of the 72 children had a clinical diagnosis of bronchopulmonary dysplasia, and the median total score and the median scores of the four most common findings were higher in the bronchopulmonary dysplasia group; however, the differences were not statistically significant. CONCLUSION: High-resolution CT in young people of preterm birth revealed abnormal radiologic findings in 81.3% of the patients at age 10 years and 92.5% at age 18 years. Linear, triangular, and subpleural opacities were the most common. The reproducibility of the applied scoring system was acceptable.

Adolescent↗

PubMed2005

Characteristics of asthma and airway hyper-responsiveness after premature birth.

Asthma-like symptoms and airway hyper-responsiveness (AHR) are frequently reported in children subsequent to premature birth and bronchopulmonary dysplasia (BPD). There is limited knowledge on the mechanisms underlying these respiratory manifestations. Generally, childhood asthma and AHR is described within a context of inheritance, allergy and eosinophilic airway inflammation, and often in relation to cigarette exposures. We investigated these factors in relation to current asthma and AHR in a population-based cohort of 81 young people, born with gestational age < or = 28 wk or birth weight < or = 1000 g, and in a matched term-born control population. In the pre-term population, asthma and AHR were additionally studied in relation to neonatal respiratory morbidity. At follow up, more pre-term than control subjects had asthma. Forced expiratory volume in first second (FEV1) was reduced, AHR was substantially increased, and the level of the urinary leukotriene metabolite E4 (U-LTE4) was increased in the pre-term population compared to the term-born. In control subjects, asthma and AHR was associated with a pattern consistent with inheritance, allergy, airway inflammation, and cigarette exposures. In the pre-terms, asthma and AHR was either unrelated or less related to these factors. Instead, AHR was strongly related to a neonatal history of BPD and prolonged requirement for oxygen treatment. In conclusion, asthma and AHR subsequent to extremely premature birth differed from typical childhood asthma with respect to important features, and AHR was best explained by neonatal variables. These respiratory manifestations thus seem to represent a separate clinical entity.

Asthma↗

PubMed2005

Assessment of lung volumes in children and adolescents: comparison of two plethysmographic techniques.

Thoracic gas volume (Vtg) can be measured with body plethysmography by either repetitive panting or one single inspiratory effort against a shutter occluding the airways. The panting technique is preferred, but may be demanding. We aimed to assess the precision of these two methods and the degree of agreement between them. Vtg and functional residual capacity (FRC) were measured in 155 subjects with a standard, commercially available plethysmograph, acting as a variable-pressure, constant-volume device when Vtg is determined. Total lung capacity (TLC) and residual lung volume (RV) were calculated subsequent to a full vital capacity manoeuvre. For non-asthmatic healthy subjects, the standard deviations (SD) of the differences between two replicate measurements of FRC, TLC and RV were respectively 0.16, 0.13 and 0.14 litres with the panting technique, and 0.18, 0.18 and 0.23 litres with the single inspiratory effort technique. In percentage of the respective lung volumes, the corresponding 1.96 SDs were 20%, 8% and 40% with the panting technique and 23%, 12% and 67% with the single inspiratory effort technique. Between the two techniques, 95% limits of agreement were 21% for FRC, 11% for TLC and 58% for RV. The variability of Vtg and FRC accounted for most of the variability of TLC and RV. In conclusion, the panting and the single inspiratory effort technique produced results that were comparable in magnitude, however with a better precision with the panting technique. The single inspiratory effort technique can be used as an alternative if the panting technique fails.

Adolescent↗

PubMed2004

Plasminogen activator inhibitor-1 increases the expression of VEGF in human glioma cells.

The level of plasminogen activator inhibitor-1 (PAI-1) in tumor tissue has been shown to be an independent negative prognostic factor in different cancers. There are several proposed reasons for this, among these, the influence of PAI-1 on tumor neovascularization and cell migration. We report that PAI-1 stimulates expression and release of vascular endothelial growth factor (VEGF) in the human glioma cell line D54Mg, and thereby stimulates the proliferation of human umbilical vein endothelial cells (HUVEC) in vitro. To search for possible molecular effects of PAI-1 on malignant cells, cDNA array hybridization analysis of D54Mg glioma cells transfected with an adenoviral PAI-1 expression vector was performed. This revealed that the VEGF response was accompanied with the simultaneous upregulation of GADD153, Rho GTPase activating protein 4 (p115), Collagen type VI alpha 1 and cell division cycle 42 (CDC42) transcripts. Exogenous treatment of D54Mg cells with a constitutively active recombinant PAI-1 protein confirmed an upregulation of VEGF expression in a time- and dose-dependent manner, and supernatants from such cultures stimulated the proliferation of human umbilical vein endothelial cells in vitro. In 44 human glioma biopsies, patients, the protein levels of PAI-1 correlated strongly with the levels of VEGF in the tumor tissues. Whereas VEGF expression correlated inversely with survival, there was no statistically significant prediction of survival by PAI-1 in this group of patients. These clinical data support and strengthen the hypothesis that PAI-1 is one of the factors regulating and inducing the VEGF expression in human gliomas. The induction of VEGF expression and thus endothelial cell proliferation may represent an as yet undiscovered mechanism whereby PAI-1 contributes to tumor neoangiogenesis.

Adenoviridae↗