Biomedical subjects

B De Clercq

Publications and source records attributed to B De Clercq.

6 recordsLinked to original sources

PubMed2006

[Prevalence of intraocular hypertension and glaucoma in a nonselected French population].

AIMS: To measure intraocular pressure (IOP) in a large human sample and to assess the prevalence of glaucoma with elevated IOP and ocular hypertension (OHT) in this population. METHODS: We measured IOP in 2,074 subjects (men: women: 1,384: 690). If the IOP was higher than 20 mmHg, a photograph of the optic disc was taken and the visual field was examined. The optic nerve head and the visual field were evaluated in 395 individuals. RESULTS: In men aged 18-39 years, mean IOP was 15.5+/-3.1 mmHg and 16.4+/-3.5 mmHg after 60 years of age. In women, IOP reached 14.5+/-3.3 and 15.9+/-3.1 mmHg, respectively. IOP greater than 21 mmHg was found in 10.1% of males and 6.4% of females. The prevalence of OHT increased with age: from 5.3% to 15.5% in men and from 3% to 7.5% in women for the same age ranges. A diagnosis of glaucoma with elevated IOP was made in 2.2% of males and 3.0% of females. The prevalence of glaucoma increased with age from 0.8% to 5.7% in men and from 0.6% to 4.7% in women under 40 years and over 60 years of age, respectively. DISCUSSION: This study confirms the increase in IOP with age and the role of aging in the prevalence of OHT and glaucoma with elevated IOP. CONCLUSION: This transversal study shows the feasibility of intraocular hypertension and glaucoma screening and prevalence assessment in a nonselected large population in France.

Adolescent↗

PubMed2003

Linking floc structure and settling properties to activated sludge population dynamics in an SBR.

Over a period of 227 days properties of activated sludge grown in an sequencing batch reactor (SBR) operated under stable conditions were analyzed. Settling properties (sludge volume index (SVI)) of the activated sludge were compared with on-line measurements of floc size and size distribution obtained by using a laser light scattering technique (Malvern Mastersizer/S, Malvern, UK), and with measurements of microbial community dynamics analyzed by denaturing gradient gel electrophoresis (DGGE) patterns of 16S rRNA genes. In addition, microscopical observations were used to confirm the results. Three distinct stages in the SBR evolution were observed. In the first stage the structural floc properties showed predominant presence of floc-forming bacteria in the activated sludge. A good correlation between floc size, properties and microbial community evolution was observed. The second stage showed a good balance between floc-forming and filamentous bacteria, with good settling properties and a highly dynamic community in the SBR. In the third stage, an increase in the filamentous bacteria, which became predominant in the system was observed. Again, a good correlation between settling properties and floc size distribution was obtained and a new dominant species was observed in the DGGE patterns, which can be assumed to be a filamentous organism.

Bioreactors↗

PubMed2002

Modelling the activated sludge flocculation process combining laser light diffraction particle sizing and population balance modelling (PBM).

A technique based on laser light diffraction is shown to be successful in collecting on-line experimental data. Time series of floc size distributions (FSD) under different shear rates (G) and calcium additions were collected. The steady state mass mean diameter decreased with increasing shear rate G and increased when calcium additions exceeded 8 mg/l. A so-called population balance model (PBM) was used to describe the experimental data. This kind of model describes both aggregation and breakage through birth and death terms. A discretised PBM was used since analytical solutions of the integro-partial differential equations are non-existing. Despite the complexity of the model, only 2 parameters need to be estimated; the aggregation rate and the breakage rate. The model seems, however, to lack flexibility. Also, the description of the floc size distribution (FSD) in time is not accurate.

Flocculation↗

PubMed2001

An overview of the posters presented at Watermatex 2000. I. New models/integrated urban wastewater systems/time series analysis.

This paper presents an overview of the posters presented in the sessions 1, 6 and 9 of the Watermatex 2000 conference. The first session focused on the development of new models in different areas of environmental technology, e.g. wastewater, ground pollution, sewers, etc. The sixth session dealt with integrated urban wastewater systems. Session 9 focused on the application of neural network modeling and principal component analysis in time series analysis. Rewarded posters are mentioned and selected for full paper publication in this issue of Wat. Sci. Tech.

Computer Simulation↗

PubMed1997

Imaging of gallbladder and biliary tract before laparoscopic cholecystectomy: comparison of intravenous cholangiography and the combined use of HASTE and single-shot RARE MR imaging.

To compare intravenous cholangiography (i.v.c.) and magnetic resonance imaging (MRI) as preoperative imaging techniques in patients scheduled for laparoscopic cholecystectomy. Twenty patients underwent i.v.c. and MRI, 40 axial 'localizer' images were first obtained with a half-Fourier single-shot turbo spin echo (HASTE) sequence. Next, an extremely high T2-weighted rapid acquisition relaxation enhancement (RARE) acquisition (TE = 1100 msec) was used for MR cholangiography. All images obtained with i.v.c. and MRI were independently analyzed by two observers. The relative visibility of the (normal or abnormal) gallbladder (GB), cystic duct (CD), and bile ducts (BD) on both types of images was scored as follows: 1 = MRI better than i.v.c.; 2 = no difference; 3 = i.v.c. better than MRI. We observed 3 anatomic variants: 1 of the cystic duct and 2 of the intrahepatic bile ducts; 15 patients had gallstones; one had cholecystitis. Magnetic resonance images were considered more informative than i.v.c.-images for visualization of GB in 11 patients (55%), for CD in 9 patients (45%), and in 8 patients (40%) for visualization of the CBD. Intravenous cholangiography outperformed MRI in the evaluation of the CBD and CD in one patient (5%). The combined use of half-Fourier single-shot RARE and high T2-weighted RARE MR imaging is a valuable alternative to i.v.c. in the preoperative evaluation of gallbladder and biliary tract.

Adult↗

PubMed1977

An epidemiological survey of virus warts of the hands among butchers.

The prevalence of virus warts of the hands among butchers has been determined in three industrial butcheries by examining 536 meat-workers at their places of work. A prevalance of 23-8% has been found, which is significantly higher than the 8-5% prevalance found in 965 control adult subjects examined in different firms where manipulation of food does not occur. Further, the prevalence of virus warts of the hands has been found significantly higher in the 199 workers of one butchery (32-1%) than in 199 control subjects (10-1%) strictly matched for age and sex, and belonging to the same industrial area. In butchers, warts of the dorsal aspects of the hands are statistically less frequent than in control subjects when three localizations are considered (dorsal, palmar, dorsal plus palmar). No significant difference is observed when single localizations (dorsal or palmar) are considered. A definite explanation of the high prevalence of virus warts of the hands among butchers has not been found so far; some hypotheses are discussed in the light of the presnt study.

Adolescent↗