Biomedical subjects

A Brix

Publications and source records attributed to A Brix.

5 recordsLinked to original sources

PubMed2001

Testing local independence between two point processes.

Dependencies between two types of points in a spatial point process can be due either to a real dependence between the two types or to the dependence on common underlying variables. We propose a global test for dependence between two point processes that is valid for a wide range of models. In contrast with previously proposed methods, it is based on a number of local test statistics, which makes it possible to map the local association between the two processes. The behavior of the test is evaluated by a simulation study. It is then applied to a vegetation pattern data set from Burkina Faso.

Burkina Faso↗

PubMed2000

[Long-term effect of inhaled budesonide in patients with mild to moderate chronic obstructive lung disease. The Osterbro Study].

We compared the effect of inhaled budesonide with placebo on decline in lung function and respiratory symptoms in a three-year study of patients with chronic obstructive pulmonary disease (COPD). We used a parallel-group, randomized, double-blind, placebo-controlled design, nested in an ongoing epidemiological survey. Patients were non-asthmatic subjects with a decreased ratio between forced expiratory volume in one second (FEV1) and vital capacity (VC); i.e., FEV1/VC < or = 0.7. All included patients had an FEV1 which was irreversible to both inhaled terbutaline and prednisolone. Two hundred and ninety patients were randomized to receive either budesonide, 1200 mcg. daily for six months followed by 800 mcg. daily for 30 months, or placebo for 36 months. Patients had a mean age of 59 years and their mean FEV1 was 2.37 liters or 86% of predicted. Crude FEV1 declines were 41.8 ml/year in the placebo group and 45.1 ml/year in the budesonide group. Using a regression model in the intention-to-treat population, patients in the placebo group had an FEV1 decline of 49.1 ml/year in contrast to 46.0 ml/year in the budesonide group; the estimated difference 3.1 ml/year (95% confidence interval--12.8-19.0) was statistically insignificant, p = 0.70. No effect of inhaled budesonide was seen on respiratory symptoms or number of exacerbations. These findings question the role of longterm inhaled corticosteroids in the treatment of mild-moderate COPD.

Administration, Inhalation↗

PubMed2000

Testing local dependence of spatial structures on images

Associations between two spatial processes can be due to a real dependence between the two processes or to the dependence on common underlying variables. We propose to test the existence of a real dependence by use of local tests, leading to a global test of real dependence and a map of local interactions. We present first how classical interaction tests based on random rotations between completely observed processes such as those developed by Berman (Berman. Appl. Statist. (1986) 35, 54-62), can be integrated in local analyses. For this purpose, tests are first performed locally, and the distribution of their p-values is then compared to the corresponding value under the null hypothesis. A similar approach is proposed to test non-stationarity of a point pattern by using distance statistics popularized by Diggle (Diggle. Statistical Analysis of Spatial Point Patterns. (1983) Academic Press, New York). The problem of testing the interaction between a random field and a censoring area pattern process is discussed and an approach similar to the preceding ones is then proposed. The methods are mainly applied to agricultural examples but they can be applied to any microscopical images for which one wishes to analyse the spatial structure.

Journal Article↗

PubMed1999

Long-term effect of inhaled budesonide in mild and moderate chronic obstructive pulmonary disease: a randomised controlled trial.

BACKGROUND: Little is known about the long-term efficacy of inhaled corticosteroids in chronic obstructive pulmonary disease (COPD). We investigated the efficacy of inhaled budesonide on decline in lung function and respiratory symptoms in a 3-year placebo-controlled study of patients with COPD. METHODS: We used a parallel-group, randomised, double-blind, placebo-controlled design in a singlecentre study, nested in a continuing epidemiological survey (the Copenhagen City Heart Study). Inclusion criteria were as follows: no asthma; a ratio of forced expiratory volume in 1 s (FEV1) and vital capacity of 0.7 or less; FEV1 which showed no response (<15% change) to 1 mg inhaled terbutaline or prednisolone 37.5 mg orally once daily for 10 days. 290 patients were randomly assigned budesonide, 800 microg plus 400 microg daily for 6 months followed by 400 microg twice daily for 30 months, or placebo for 36 months. The mean age of the participants was 59 years and the mean FEV1 2.37 L or 86% of predicted. The main outcome measure was rate of FEV1 decline. Analyses were by intention to treat. FINDINGS: The crude rates of FEV1 decline were slightly smaller than expected (placebo group 41.8 mL per year, budesonide group 45.1 mL per year). The estimated rates of decline from the regression model did not differ significantly (49.1 mL vs 46.0 mL per year; difference 3.1 mL per year [95% CI -12.8 to 19.0]; p=0.7). Before the study, the minimum relevant difference was defined as 20 mL per year; this difference was outside the 95% CI. No effect of inhaled budesonide was seen on respiratory symptoms. 316 exacerbations occurred during the study period, 155 in the budesonide group and 161 in the placebo group. Treatment was well tolerated. INTERPRETATION: Inhaled budesonide was of no clinical benefit in COPD patients recruited from the general population by screening. We question the role of long-term inhaled corticosteroids in the treatment of mild to moderate COPD.

Administration, Inhalation↗

PubMed1999

The safety of OP-1 for lumbar fusion with decompression-- a canine study.

OBJECTIVE: Bone morphogenetic proteins can serve as adjuncts to autologous bone to achieve bony fusion, and recombinant BMPs such as osteogenic protein-1 (OP-1) have the potential to replace autologous bone altogether as fusion substrate. However, relatively little is known about the safety of OP-1 for spinal fusion procedures. This study examined the effects of OP-1 intentionally placed in the subarachnoid space following thecal sac decompression, and used as graft substrate in a canine dorsolateral lumbar spine fusion model. METHODS: Lumbar decompression with dorsolateral fusion was performed on 30 canines. The dura was opened to simulate an intraoperative rent and OP-1 was placed in the subarachnoid space and in the fusion bed. Animals were sacrificed after 16 weeks and the spines were examined manually, radiographically and pathologically. RESULTS: All animals treated with OP-1 developed new bone in the subarachnoid space. This bone compressed the spinal cord, but no clinical or pathological features of neurotoxicity were noted. Mild spinal stenosis was noted at the site of dural decompression in the OP-1 treated animals. Over 80% of animals treated with OP-1 developed fusion as assessed by palpation (52% by CT criteria), while only 25% of control animals fused. CONCLUSIONS: Recombinant human OP-1 is effective at promoting fusion in a canine dorsolateral lumbar spine fusion model. However, bone growth can occur over exposed, decompressed dura, and it can form in the subdural and subarachnoid spaces. The use of OP-1 as an adjunct to spinal fusion appears to have merit, but its use must be carefully controlled to avoid unwanted bone formation and subsequent neural compression.

Animals↗