Biomedical subjects

F Romijn

Publications and source records attributed to F Romijn.

4 recordsLinked to original sources

PubMed2006

Arsenic-induced toxicity: effect on protein composition in sciatic nerve.

Exposure to arsenic compounds may lead to skin and lung cancer and various disorders such as vascular disease and peripheral neuropathy in humans. Peripheral arsenic neurotoxicity has been demonstrated clinically and in electrophysiological studies. Patients intoxicated with arsenic show neurological symptoms in their feet and hands. These patients show significantly lower nerve conduction velocities (NCVs) in their peripheral nerves in comparison with controls. The mechanism of arsenic peripheral nervous system (PNS) toxicity, however, has never been described before. This is the first study to investigate the toxicity of arsenic on the PNS. Male Wistar rats were exposed to arsenite given as a single dose i.v. After sacrifice, sciatic nerves were excised and the protein composition was analysed. Protein analysis of sciatic nerves showed disappearance of neurofilament and fibroblast proteins in rats treated with arsenite doses of 15 and 20 mg/kg in comparison with the control groups. Some fibroblast protein bands had disappeared in the 20-mg/kg dose group. The analysed neurofilament-M and -L proteins decreased dose dependency over time. arsenic affects the composition of proteins in the rat sciatic nerve, especially the neurofilaments. The reduction of signals in Western blot analysis reveals changes in cytoskeletal composition, which may well lead to neurotoxic effects in vivo.

Animals↗

PubMed2000

Activated platelets in patients with severe hypertriglyceridemia: effects of triglyceride-lowering therapy.

Hypertriglyceridemia, a risk factor for cardiovascular disease, has been associated with hypercoagulability, but whether platelet activation is implicated is unknown. This study was designed to compare the in vivo platelet activation status between patients with severe hypertriglyceridemia and age- and sex-matched control subjects, and to evaluate the effects of triglyceride-lowering therapy. Sixteen patients with primary hypertriglyceridemia were included in a double-blind, placebo-controlled cross-over trial with 400 mg bezafibrate once daily. Platelet activation was analysed by double label flow cytometry, using monoclonal antibodies against GP53, P-selectin, and platelet-bound fibrinogen. Surface expression of the lysosomal membrane protein GP53 was significantly higher in the hypertriglyceridemic patients at baseline as compared to the group of age- and sex-matched controls (16.3+/-4.8% vs. 8.9+/-3.4%, respectively, P<0.001). No differences in the expression of P-selectin and fibrinogen binding were observed. In response to bezafibrate therapy, the expression of GP53 in the patient group decreased from 16.3+/-4.8% to 13.1+/-4.1% (P=0.018). The expression of P-selectin and fibrinogen binding was not affected by bezafibrate therapy. In conclusion, patients with hypertriglyceridemia have an increased in vivo platelet activation status, which can be improved by bezafibrate therapy.

Antigens, CD↗

PubMed2000

The amount of free corticosterone is increased during lipopolysaccharide-induced fever.

The relation between lipopolysaccharide (LPS)-induced fever and bioavailability of corticosterone (B) was examined in male Wistar rats. Animals were injected with LPS (2.5 mg/kg i.p.) or saline and core temperature and heart rate were monitored continuously using a biotelemetry system. Blood samples were withdrawn from freely moving rats via jugular catheters for estimation of total and free plasma B. LPS induced a long-lasting increase (24-48 h) in core temperature and B secretion and a short-lasting increase (90 min) in heart rate. LPS-induced fever was accompanied by a significant increase in the free/total B ratio. In contrast, an acute injection of B, which resulted in circulating B levels similar to those found after LPS, did not affect the free/total B ratio. The important role of LPS-induced fever in the hormone secretion pattern and the equilibrium between free and total B was further demonstrated in an in vitro study showing that an increase in the temperature by 3 degrees C elevated the free B fraction and the free/total B ratio of plasma samples with concentrations of B in the physiological range (5-40 microg/dl). Taken together, these findings indicate that during LPS-induced fever there is an increase in the amount of biologically available B. Exposure of glucocorticoid-sensitive targets to elevated levels of free B could contribute to the restoration of homeostasis that is disturbed during inflammation.

Animals↗

PubMed1993

Free cortisol in serum assayed by temperature-controlled ultrafiltration before fluorescence polarization immunoassay.

A method is described for a temperature-controlled ultrafiltration procedure to measure free cortisol in serum. A special thermometer with a sensor was developed, measuring the temperature directly in the ultrafiltration device. The sensor is screwed on the axis of the centrifuge rotor, and the centrifuge is placed in a temperature-controlled box so that the temperature of the sample is kept at 37 degrees C +/- 0.1 degrees C. The overall CV of the free cortisol assay ranges from 2.2% to 11.4%, of which the ultrafiltration contributes only 2.2-3.6%. Increasing amounts of cortisol-binding protein, as found in women using estrogen-containing oral contraceptives, have minor but significant effects on the free cortisol concentrations in serum. Serum free cortisol concentrations in a reference population (n = 114; central 95 percentiles) were 12-43 nmol/L (4-9.5% of total cortisol); in the group of the oral-contraceptive users (n = 27), the reference interval was 11-53 nmol/L (1.5-4.5%).

Blood Preservation↗