Biomedical subjects

J Evers

Publications and source records attributed to J Evers.

49 records · Page 3Linked to original sources

PubMed1983

Pharmacokinetics of brotizolam in renal failure.

Kinetics of brotizolam (0.25 mg) were studied in patients with different degrees of renal failure after single and repeated oral ingestion. Serum levels were analysed by radio-immunoassay. Patients were divided into three groups according to their renal function, i.e. creatinine clearance values of 45-80, 15-45, or less than 15 ml/min. The mean elimination half-life was 6.9-8.15 h, with a considerable variation of the peak concentration and elimination half-life in slight to moderate renal failure. There was no delay in elimination in severe renal failure and there was no drug accumulation. No dose adjustment is necessary for brotizolam in renal failure.

Adult↗

PubMed1981

Transcephalic impedance in the neonate: an indicator of intracranial hemorrhage, asphyxia, and delayed maturation.

Increased transcephalic impedance readings (greater than 3 SD) were recorded in 13 asphyxiated infants 35 weeks or more in gestation, and in 13 preterm infants 34 weeks or less in gestation and with intracranial hemorrhage (greater than 2 SD). Six infants had decreased TCZ recordings in the weeks following intracranial hemorrhage, without ultrasound evidence of ventricular enlargement. TCZ provides quick, inexpensive, noninvasive indication of tissue necrosis, moderate-to-severe intracranial hemorrhage, and delayed brain maturation.

Asphyxia Neonatorum↗

PubMed1979

Quality assurance of gram-stained direct smears.

Clinical laboratories do not always prepare and examine direct smears. In part, this may be explained by lack of control over the precision and accuracy of the procedure, which has diminished confidence in direct smears among both laboratory scientists and clinicians. Objective criteria were established for enumeration of cells and placement of bacteria in identification categories. Two methods for monitoring the accuracy and reproducibility of their application were studied: (1) examination of previously examined and reported direct smears of clinical specimens by independent observers with subsequent review of discrepancies with decisions by personnel; (2) preparation of suspensions of cells and bacteria that yielded identical smears for subsequent examination as unknowns. Method 1 showed agreement in bacterial identification category in 65%, quality score 74%, enumeration of neutrophils 79%, squamous cells 76%, and erythrocytes 92%. Method 2 showed that conformance of technologists' observations to expected results varied, for neutrophils conformance was 72-78%, squamous cells, 68-78%, bacterial identification category, 100%, and bacterial enumeration, 45-96%.

Cell Count↗

PubMed1979

Evidence for a therapeutic effect of plasmapheresis in patients with systemic lupus erythematosus.

Fourteen patients with active systemic lupus erythematosus (SLE) have been treated with plasmapheresis at a rate of two litres daily on three to four days per week, over a period of two to three weeks. Plasma was replaced isovolemically with either fresh frozen plasma or with human plasma protein fractions. Ten patients were receiving treatment with prednisone at the time of plasmapheresis, and four had received no prior treatment. Eight patients showed evidence of either clinical improvement or clinical and immunochemical improvement, at the time of plasmapheresis. In the three patients who showed high levels of circulating complexes before treatment, there was a sudden fall in the level of circulating immune complexes, which was quantitatively greater than could be explained by the amount removed. This suggests that in some patients with SLE, clearance of complexes by the mononuclear phagocytic system is initially blocked by high levels of circulating complexes and that one effect of plasmapheresis may be to relieve this blockade. Five patients showed a clinical response to plasmapheresis despite the fact that tests for immune complexes were negative. Three patients showed no response to plasmapheresis, and three were regarded as unevaluable. In a limited number of patients, who show a high level of circulating immune complexes, and whose condition is deteriorating despite treatment with corticosteroids, there may be an important therapeutic role for plasmapheresis.

Adolescent↗

PubMed1976

Phenylalanine uptake in isolated renal brush border vesicles.

The uptake of L-phenylalanine into brush border microvilli vesicles and basolateral plasma membrane vesicles isolated from rat kidney cortex by differential centrifugation and free flow electrophoresis was investigated using filtration techniques. Brush border microvilli but not basolateral plasma membrane vesicles take up L-phenylalanine by an Na+-dependent, saturable transport system. The apparent affinity of the transport system for L-phenylalanine is 6.1 mM at 100 mM Na+ and for Na+ 13mM at 1 mM L-phenylalanine. Reduction of the Na+ concentration reduces the apparent affinity of the transport system for L-phenylalanine but does not alter the maximum velocity. In the presence of an electrochemical potential difference of Na+ across the membrane (etaNao greater than etaNai) the brush border microvilli accumulate transiently L-phenylalanine over the concentration in the incubation medium (overshoot pheomenon). This overshoot and the initial rate of uptake are markedly increased when the intravesicular space is rendered electrically more negative by membrane diffusion potentials induced by the use of highly permeant anions, of valinomycin in the presence of an outwardly directed K+ gradient and of carbonyl cyanide p-trifluoromethoxyphenylhydrazone in the presence of an outward-directed proton gradient. These results indicate that the entry of L-phenylalanine across the brush border membrane into the proximal tubular epithelial cells involves cotransport with Na+ and is dependent on the concentration difference of the amino acid, on the concentration difference of Na+ and on the electrical potential difference. The exit of L-phenylalanine across the basolateral plasma membranes is Na+-independent and probably involves facilitated diffusion.

Animals↗

PubMed1976

Polarity of proximal tubular epithelial cells in relation to transepithelial transport.

Transport properties of brush border microvilli and basal-lateral plasma membranes isolated from rat kidney cortex were studied by a millipore filtration technique. Brush border microvilli but not basal-lateral plasma membranes contain sodium dependent stereospecific transport system for D-glucose, L-phenylalanine and inorganic phosphate as indicated by saturability, countertransport and inhibition by structurally related compounds. Reduction of equilbrium uptake by increasing medium osmolarity suggests transport into an osmotically reactive space rather than binding to the membranes. Electrogenecity of the sodium-sugar and sodium-amino-acid cotransport system was established by their dependence on artificially imposed diffusion potentials. Also a NA+/H+ antiport system can be demonstrated in microvilli vesicles by demonstrating counterflow of both ions under short circuit conditions. Basal-lateral plasma membranes contain sodium independent stereospecific transport systems for sugars and amino acids. These results demonstrate a marked functional polarity of the cell membranes in respect to sodium dependent and sodium independent transport systems. This polarity in conjunction with the asymmetrical distribution of sodium between the intra- and extracellular space seems to enable the proximal tubule epithelial cells to perform active transepithelial transport.

Animals↗

PubMed1969