Search PubMed⌕ Search

Biomedical subjects

A De Vos

Publications and source records attributed to A De Vos.

52 records · Page 3Linked to original sources
PubMed1995

Wegener granulomatosis is associated to exposure to silicon compounds: a case-control study.

Wegener granulomatosis is a rare disease of unknown aetiology. In the majority of these patients the kidney is involved in the disease process. We performed a case-control study to evaluate the role of occupational exposure in the development of Wegener granulomatosis with renal involvement. The occupational histories of 16 cases with clearly established diagnosis of Wegener granulomatosis with renal involvement were compared with those of 32 age- and sex-matched controls. It was observed that inhalation of silicon-containing compounds such as silica and grain dust gave a nearly sevenfold risk for Wegener granulomatosis. Further epidemiological and experimental work needs to be performed in order to corroborate these findings.

Adult↗
PubMed1994

Release of indomethacin from transparent oil-water gels.

Within the scope of evaluating transparent oil-water gels (TOW gel) as dermatological vehicles, the release of indomethacin from a model TOW gel into 1-dodecanol is studied at various pH levels of the water phase. Apparent partition coefficient determinations and flame photometrical measurements show that both indomethacin and its sodium salt, as the ion pair, migrate into the 1-dodecanol layer. The pH-dependent release-rate profile is explained in terms of the amount of readily diffusible drug in the water phase of the gel.

Chemical Phenomena↗
PubMed1994

Differential depolarization-activated calcium responses in fetal and neonatal rat osteoblast-like cells.

The present study evaluates differential occurrence of voltage-dependent calcium channels (VDCC) in the membranes of fetal (FROB) and neonatal (NROB) calvarian rat osteoblastic cells in primary culture. The intracellular calcium concentration ([Ca2+]i) was monitored upon depolarization of the cell membrane with the use of high K+ containing extracellular solutions. [Ca2+]i was measured in populations of cells as well as in individual cells using Fura-2, whereas the membrane potential (Em) was recorded in parallel experiments using patch-clamp techniques. Increasing the extracellular K+ concentration resulted in an instantaneous depolarization of Em of both FROB and NROB. This depolarization of Em did not significantly affect [Ca2+]i of populations of FROB and neonatal osteoblast precursors (NpROB). In contrast to FROB and NpROB, NROB populations responded to depolarization with significant transient [Ca2+]i increases that could be blocked by the calcium antagonist verapamil and were absent if extracellular Na+ was replaced for choline instead of K+. In individual cell measurements, response frequencies as well as the magnitude of [Ca2+]i responses upon depolarization of NROB were much higher than those of FROB, suggesting that more NROB than FROB possess VDCC. This phenomenon might point to a development-related expression of VDCC in the membranes of osteoblast-like cells.

Animals↗
PubMed1993

Heterogeneity in glucose sensitivity among pancreatic beta-cells is correlated to differences in glucose phosphorylation rather than glucose transport.

Rat beta-cells differ in their individual rates of glucose-induced insulin biosynthesis and release. This functional heterogeneity has been correlated with intercellular differences in metabolic redox responsiveness to glucose. The present study compares glucose metabolism in two beta-cell subpopulations that have been separated on the basis of the presence (high responsive) or absence (low responsive) of a metabolic redox shift at 7.5 mM glucose. Mean rates of glucose utilization and glucose oxidation in high responsive beta-cells were 2- to 4-fold higher than in low responsive beta-cells, whereas their leucine and glutamine oxidation was only 10-50% higher. This heterogeneity in glucose metabolism cannot be attributed to differences in GLUT2 mRNA levels or in glucose transport. In both cell subpopulations, the rates of glucose transport (13-19 pmol/min/10(3) beta-cells) were at least 50-fold higher than corresponding rates of glucose utilization. On the other hand, rates of glucose phosphorylation (0.3-0.7 pmol/min/10(3) beta-cells) ranged within those of total glucose utilization (0.2-0.4 pmol/min/10(3) beta-cells). High responsive beta-cells exhibited a 60% higher glucokinase activity than low responsive beta-cells and their glucokinase mRNA level was 100% higher. Furthermore, glucose phosphorylation via low Km hexokinase was detected only in the high responsive beta-cell subpopulation. Heterogeneity in glucose sensitivity among pancreatic beta-cells can therefore be explained by intercellular differences in glucose phosphorylation rather than in glucose transport.

Amino Acids↗
PubMed1991

Preferential stimulation by glucose of its oxidation relative to glycolysis in purified insulin-producing cells.

A rise in extracellular D-glucose concentration increases to a greater relative extent the conversion of both D-[5-3H]glucose to 3HOH and D-[6-14C]glucose to 14CO2 in rat purified insulin-producing cells than previously observed in pancreatic islets. In the pure B-cells, the ratio between D-[6-14C]glucose oxidation and D-[5-3H]glucose utilization increases, in a sigmoidal manner, as a function of the hexose concentration. The preferential stimulation by D-glucose of mitochondrial oxidative events is proposed to represent an unusual but essential feature of the metabolic and, hence, functional response of these fuel-sensor cells.

Acetyl Coenzyme A↗
PubMed1990

A pipette holder for use in patch-clamp measurements.

A novel design for a pipette holder for use in patch-clamp experiments is presented. The holder is designed for use in patch-clamp amplifiers equipped with female BNC-type connectors on the headstage. In this design the glass micropipette cannot contact the Ag/AgCl electrode, thus avoiding deterioration and subsequent offset voltages and baseline current drifts of the Ag/AgCl electrode, induced by frequent replacement of micropipettes.

Electrophysiology↗
PubMed1983

Micro-CO2-incubator for use on a microscope.

A simple micro-CO2-incubator designed for use on the stage of an inverted microscope is described. This micro-incubator is easy to use, offers a handy tool for the culture of cells under the microscope and its performance compares well with that of a conventional CO2-incubator. A standard disposable culture dish can be placed in the micro-incubator. The culture medium is covered by a gas-permeable layer of mineral oil, this protects the culture from the environment without affecting the culture conditions and allows easy cell manipulation under microscopical control.

Animals↗
PubMedDate not supplied

The Brussels' experience of more than 5 years of clinical preimplantation genetic diagnosis.

This paper describes the 5 years' experience of preimplantation genetic diagnosis (PGD) at the Brussels Free University. Our first PGD was carried out in February 1993. Up to October 1998, we carried out 183 PGD cycles on fresh cleavage embryos of 92 couples for 25 different conditions. Patients were treated for autosomal recessive (n = 39), autosomal dominant (n = 65) and X-linked recessive (n = 47) monogenic disorders as well as for autosomal structural aberrations (n = 10), sex chromosome numerical and structural aberrations (n = 21) and a combination of the two latter (n = 1). Specific diagnosis was carried out by polymerase chain reaction (n = 108). Fluorescence in-situ hybridization was used for sexing (n = 64) and structural aberrations (n = 11). We transferred 1.6 +/- 1.1 embryos per cycle, resulting in an implantation rate of 12.0% per replaced embryo. Ongoing pregnancies were achieved in 29 cycles, i.e. 23 singletons, five twins and one dichorionic triplet with an acardius acranius. The ongoing pregnancy rates per cycle, per transfer and per couple were 16.4, 19.9 and 31.5% respectively. While 28 ongoing pregnancies resulted in the births of 34 infants, one pregnancy was terminated after misdiagnosis. The results of 24 PGD were confirmed by prenatal diagnosis or after birth while no information was available in four pregnancies. Our series demonstrates that PGD is a feasible technique by which to avoid the birth of genetically affected children to couples at risk.

Adult↗
PubMedDate not supplied

[Anorectal tumor pathology and its diagnosis].

Anal cancer is very rare, but its diagnosis is often too late. Treatment is usually non surgical and can be very effective. Prognosis can be improved by earlier diagnosis. Proctoscopy is mandatory for all symptomatic patients. Could an high risk population be determined, the incidence of anal cancer could fall. By contrast, rectal cancer is one of the most frequent and its prognosis has not been improved. Hope can be found in screening and prevention; these will be more effective when the transformation sequence of adenoma to cancer will be entirely explained.

Aged↗