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Biomedical subjects

J Roels

Publications and source records attributed to J Roels.

9 recordsLinked to original sources
PubMed2003

Occurrence and origin of phosphine in landfill gas.

A landfill (Hooge Maey, Flanders, Belgium) was subjected to an in-depth study in order to explain the origin of phosphine detected in high amounts in landfill gas during a previous study. The spatial and temporal variability of the phosphine concentration in landfill gas was assessed. Twenty four wells were monitored and differences in phosphine concentration up to one log unit were observed (3.2-32.4 microg/m3). The phosphine concentration in each well was constant in time over a period of 4 months. No correlation was found between the phosphine concentration and methane, carbon dioxide, hydrogen sulphide, ethene or ethane concentration. In a series of laboratory tests, it was shown that phosphine was emitted during batch fermentation tests inoculated with landfill leachate when Fe0 or Al0 specimens were added. Conditions favouring corrosion of iron gave rise to higher emissions of phosphine. The phosphine concentration in the headspace of a batch test rose to 1.43 mg/m3 after 27 days of incubation. Weight loss of corroding steel coupons correlated with phosphine emission. Calculations showed that all phosphine emitted from the 0.005 km3 landfill (160 g/year) could be attributed to corrosion of metals. No evidence of de novo synthesis could be established

Air Pollutants↗
PubMed2001

Biological formation of volatile phosphorus compounds.

Phosphine and phosphides are reported to occur at numerous environmental sites such as fresh and marine sediments, landfills, faecal matter, biogas digesters and soils. The concentrations are several log units lower than the time-weighted average exposure standard, i.e. in the order of ng per m3 of gas or ng per kg material. Research about the biological formation of highly reduced gaseous phosphorus compounds dates back more than a hundred years. The early reports had to deal with a lot of scepticism. Thanks to new analytical tools (gas chromatography) it has become clear, during the last decade, that phosphine is a global constituent of the atmosphere. Pure strains of micro-organisms cultivated under highly anaerobic conditions were shown to produce phosphine. Thermodynamic considerations indicate that it is very improbable that the reduction of phosphate to phosphine is endergonic. Therefore the generation of phosphine cannot be compared with sulphidogenesis and methanogenesis. There seems to be a link between the existence of highly reactive gaseous phosphorus compounds and increased levels of metal corrosion. The reactive compounds could be formed by micro-organisms or they are liberated from phosphorus-containing impurities in the iron by the action of bacterial metabolites. The biochemical pathways responsible for the production of gaseous phosphorus compounds have not been characterised yet.

Chromatography, Gas↗
PubMed1993

Immunohistochemical analysis of E-cadherin expression in human colorectal tumours.

The homotypic homophilic cell-cell adhesion molecule E-cadherin is crucial in the organization and maintenance of most epithelia. The expression of E-cadherin was studied immunohistochemically in various human colorectal tumours. Therefore we stained 1 tubular adenoma with low grade dysplasia, 18 adenocarcinomas with different histologic degrees of differentiation and invasion, and 1 metastasis using a modified peroxidase-anti-peroxidase technique. In the adenoma as well as in all well differentiated adenocarcinomas we found E-cadherin immunopositivity at the cell membrane of almost all cancer cells. The immunopositivity of E-cadherin was clearly weaker and sometimes even absent in isolated neoplastic cells and glands of less differentiated adenocarcinomas. The moderately differentiated adenocarcinomas showed an intermediate staining pattern. These findings are in line with experimental evidence that downregulation of E-cadherin favours invasion, eventually leading to metastasis.

Adenocarcinoma↗
PubMed1989

Radiographic measurement from the lateromedial projection of the equine foot with navicular disease.

Radiographic measurements from the lateromedial projection of the equine foot were compared in three groups of horses. Group 1 consisted of 143 normal horses, group 2 were 60 horses with clinical navicular disease and group 3 were 161 horses with clinical and radiographic navicular disease. Several measurements tended to be larger in group 3 than group 1. An enlargement of the navicular bone was observed in proximodistal and dorsopalmar directions. Partial enlargement of the pedal bone was observed in groups 2 and 3. Few differences were observed between age classes. All horses aged four years and over had an increased length of the hoof in the dorosopalmar direction and a decrease of the cranial angle of the hoof. Enlargement of the navicular bone fits well into the concept of osteoarthrosis. The pedal bone was partly engaged. These findings may be an expression of a regional acceleratory phenomenon.

Animals↗
PubMed1983

Intracranial pressure changes in patients with head trauma during haemodialysis.

Intracranial hypertension and acute renal failure are frequent complications in polytraumatized patients with head trauma. This paper deals with the evolution of intracranial pressure during haemodialysis in two cases of traumatic coma. Significant changes in intracranial pressure were noted. Increase of intracranial pressure during haemodialysis was 7.6 mmHg for the first patient and 4.6 mmHg for the second patient. Prophylactic measures are discussed.

Acute Kidney Injury↗
PubMedDate not supplied

Patellar tendinitis (jumper's knee).

A jumper's knee is an overload lesion of patellar or quadriceps tendon near its insertion at the lower or upper pole of the patella. If conservative treatment fails, an operation can be performed in Phase 3 where disabling symptoms, are present. The necrotic tissue in the patellar tendon is excised. The early results of this surgery are encouraging.

Humans↗