PubMed Health⌕ Search

Biomedical subjects

J Geurts

Publications and source records attributed to J Geurts.

At least 19 recordsLinked to original sources
PubMed2002

Chemical surface analysis by Raman spectroscopy utilizing dimer vibrations.

We report on the investigation of reconstructed semiconductor surfaces by Raman spectroscopy from dimer vibrations. Localized modes of Te dimers on the (100) surface of the zinc blende II-VI semiconductor BeTe allow the analysis of Te- and Be-rich surface structures, as well as oxidation effects. The Te-rich surface exhibits one dimer-vibration mode at 165 cm(-1), while two modes appear at the Be-rich surface (157 and 188 cm(-1)). The mode assignment as dimer vibrations is underscored by their symmetry properties and by frozen phonon calculations, yielding mode frequencies and eigenvectors. This approach opens up a new field of surface chemistry analysis by dimer-vibration spectroscopy.

Journal Article↗
PubMed2001

Immunohistochemical localization of group I and II metabotropic glutamate receptors in control and amyotrophic lateral sclerosis human spinal cord: upregulation in reactive astrocytes.

Excitotoxicity, which is mediated by the excessive activation of glutamate receptors, has been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). There is substantial information about the distribution and function of ionotropic glutamate receptors in the spinal cord, although the role of metabotropic glutamate receptors (mGluRs) is poorly understood in this region of the brain, particularly under pathological conditions. We used immunocytochemistry to study the general distribution of group I and group II mGluR immunoreactivity in the human spinal cord, as well as the cell-specific expression of these receptors. We also investigated whether mGluR expression was altered in the spinal cord of patients with sporadic and familial ALS. Immunocytochemical analysis of control human spinal cord demonstrated that mGluR1alpha and mGluR5 (group I mGluRs) were highly represented in neuronal cells throughout the spinal cord. mGluR1alpha showed the highest relative level of expression in ventral horn neurons (laminae VIII and IX), whereas intense mGluR5 immunoreactivity was observed within the dorsal horn (superficial laminae I and II). Group II mGluRs (mGluR2/3) immunoreactivity was mainly concentrated in the inner part of the lamina II. With respect to specific neuronal populations, mGluR2/3 and mGluR5 appeared to be most frequently expressed in calbindin-containing and calretinin-containing cells, respectively. In control spinal cord only sparse astrocytes showed a weak to moderate mGluR immunoreactivity. Regional differences in immunoreactivity were apparent in ALS compared to control. In particular, mGluR expression was increased in reactive glial cells in both gray (ventral horn) and white matter of ALS spinal cord. Upregulation of mGluRs in reactive astrocytes may represent a critical mechanism for modulation of glial function and changes in glial-neuronal communication in the course of neurodegenerative diseases.

Adult↗
PubMed2000

Equity in the delivery of health care in Europe and the US.

This paper presents a comparison of horizontal equity in health care utilization in 10 European countries and the US. It does not only extend previous work by using more recent data from a larger set of countries, but also uses new methods and presents disaggregated results by various types of care. In all countries, the lower-income groups are more intensive users of the health care system. But after indirect standardization for need differences, there is little or no evidence of significant inequity in the delivery of health care overall, though in half of the countries, significant pro-rich inequity emerges for physician contacts. This seems to be due mainly to a higher use of medical specialist services by higher-income groups and a higher use of GP care among lower-income groups. These findings appear to be fairly general and emerge in countries with very diverse characteristics regarding access and provider incentives.

Data Collection↗
PubMed1997

Income-related inequalities in health: some international comparisons.

This paper presents evidence on income-related inequalities in self-assessed health in nine industrialized countries. Health interview survey data were used to construct concentration curves of self-assessed health, measured as a latent variable. Inequalities in health favoured the higher income groups and were statistically significant in all countries. Inequalities were particularly high in the United States and the United Kingdom. Amongst other European countries, Sweden, Finland and the former East Germany had the lowest inequality. Across countries, a strong association was found between inequalities in health and inequalities in income.

Developed Countries↗
PubMed1987

Supplier-induced demand for physiotherapy in the Netherlands.

Empirical studies of supplier-induced demand in health care have mostly concentrated on the analysis of physician behaviour. In this article, the focus is on the economic determinants of physiotherapist behaviour in The Netherlands. It is shown that relative prices work as strong incentives to alter the mix of services supplied, conform to the model of revenue maximization under a production constraint. However, the time-series analysis also gives some indication that this ability to influence the demand for their services to increase hourly income is not fully exploited. The latter finding is inconsistent with pure income maximization but rather points to a trade-off between loss of revenue and demand manipulation. The fact that the choice of therapy varies with the pressure on provider incomes does not cast some doubt on the appropriateness of the chosen patterns of treatment in terms of effectiveness.

Health Services Needs and Demand↗
PubMed1985

Magnesium administration reverses the hypocalcaemia secondary to hypomagnesaemia despite low circulating levels of 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D.

The effect of parenteral administration of magnesium was studied in five patients with hypomagnesaemic hypocalcaemia. The initial metabolic state was characterized by a normal level of serum immunoreactive parathyroid hormone (iPTH), and by low or undetectable serum 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25 (OH)2D). A parathyroid response was elicited by the acute intravenous injection of magnesium chloride. In contrast, 1,25(OH)2D did not change up to 24 h after the injection. Intramuscular magnesium sulphate restored serum magnesium and calcium to normal, whereas iPTH was transiently increased. 25OHD remained low and unchanged. 1,25(OH)2D rose very slowly, but the correction of hypocalcemia began before any change in 1,25(OH)2D levels could be demonstrated. Thus, the early correction of hypocalcemia mainly depended on the restoration of an adequate parathyroid function independently of the secretion of 1,25(OH)2D.

25-Hydroxyvitamin D 2↗
PubMed1982

A comparative study of the patello-femoral joint on axial roentgenogram, axial arthrogram, and computed tomography following arthrography.

After arthrography 71 young patients with pain in the knee had a computed tomography (CT) examination. The form of the patella is classified according to the method of Wiberg [12] and on CT 50% of them do not correspond to the type described on the axial roentgenogram. The position of the patella can be examined on CT with a relaxed knee in 15 degrees of flexion. The patellar cartilage is easier to assess on CT: congruity, regularity, imbibition of contrast material and thickness are studied.

Adolescent↗
PubMed1982

The value of computed tomography scanning in chondromalacia patellae.

Sixty seven patients with pain in the knee were studied. A compound tomography (CT) score indicating chondromalacia was devised, based on the results of CT after arthrography. This score takes account of the regularity, the congruity, and the imbibition of contrast material. Thus the patients could be divided into four groups: those who definitely have chondromalacia (++), probably (+), probably not (+/-), and definitely not (-). These results were compared with the clinical diagnosis based on clinical signs, arthroscopy, or operation. Eighteen patients had clinically proved chondromalacia, CT scored 14++, 3+ and 1+/-. Twenty nine patients had no chondromalacia, CT scored 19-, 8+/-, and 2+. Twenty patients had an uncertain clinical diagnosis. Arthrography was less accurate in detecting chondromalacia.

Adolescent↗
PubMed1981

Alterations in circulating thyroid hormones and thyroxine binding globulin in chronic alcoholism.

The present study concerns eighteen chronic alcoholics with minimal liver damage. A significant reduction in total serum T4 with an accompanying drop in circulating TBG was observed in these otherwise euthyroid patients. During alcohol withdrawal, we observed a rapid increase in T4 and TBG into the normal range. We suggest that the fall in the level of circulating thyroxine-binding globulin is related to a defect in its synthesis or secretion by the liver due to ethanol consumption. Caution is recommended in the interpretation of thyroid function tests in chronic alcoholics.

Adult↗
PubMed1979

[Pseudomonas cepacia hospital infections; uncertainties and experiences with an epidemiological investigation (author's transl)].

During a hospital outbreak of Pseudomonas cepacia a traditional epidemiological investigation was proved to be misleading. Suppression of the suspected antiseptic did not stop the epidemics. A further investigation proved that it was due to the intravenous injection of contamineted anesthetic vials. Fever, chills, lack of hemodynamic disorders and of metastatic absceses characterize the clinical state of the infected patients. The removal of the catheters for perfusion was sometimes necessary to stop the bacteraemia. A lack of medical information is responsible of the outbreak.

Anesthetics↗
PubMed1979

Effect of rapid variation of renal function on plasma calcitonin and parathyroid hormone in man.

Plasma levels of immunoreactive calcitonin (iCT) and parathyroid hormone (iPTH) have been measured sequentially in 6 patients following successful renal transplantation (RT) and in 3 patients during the recovery phase of acute renal failure (ARF). iCT and iPTH returned to normal values within a few days when glomerular filtration improved; both hormones rose in cases of acute graft rejection. Unlike iPTH iCT did not follow closely the variations of creatinine, iCT even rising before creatinine in one graft rejection. These observations could possibly be explained by a dissociation between the renal metabolism of iCT and the glomerular filtration.

Acute Kidney Injury↗
PubMed1978

The use of a test for the differential diagnosis of hypercalciuria.

28 renal stone formers (18 men and 10 women) with idiopathic hypercalciuria (IH) and 27 controls have been subjected to a test proposed for the diagnosis of absorptive, resorptive and renal hypercalciurias. Fasting serum calcium concentration, urinary calcium and cyclic AMP excretion were measured after overnight fasting and an oral load of calcium. Absorptive hypercalciuria was demonstrated in 14 patients. High fasting urinary calcium first suggested resorptive or renal hypercalciurias in 5 other patients, but since fasting urinary calcium was normalized following cellulose phosphate therapy, absorptive hypercalciuria was more likely. Renal hypercalciuria was a possibility in 1 single case. Both fasting and post-load urinary calcium were normal in 7 men and 1 woman. The test did not appear as useful as expected since it was of no diagnostic value in about 30% of the cases and erroneously suggested resorptive or renal hypercalciuria in about 15% of the cases. On the other hand it indicated that absorptive IH is common and renal IH exceptional.

Adult↗