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Biomedical subjects

S Baar

Publications and source records attributed to S Baar.

At least 19 recordsLinked to original sources
PubMed1990

Effect of surgery on the systemic inflammatory response to intermittent claudication.

The hypothesis that intermittent claudication initiates a systemic inflammatory response was investigated by studying the effect of exercise on markers of neutrophil activation and vascular permeability in 25 claudicants and 10 controls. Urinary albumin excretion, previously demonstrated to reflect vascular permeability, increased significantly after exercise in claudicants and was associated with decreased neutrophil filterability and increased serum lysozyme activity. No similar exercise-induced changes were seen in controls or in claudicants after successful arterial bypass surgery. These results suggest that intermittent claudication is associated with potentially deleterious systemic manifestations that are surgically reversible.

Aged↗
PubMed1990

A convenient and reproducible filtration technique for the determination of erythrocyte deformability.

A simple method for the determination of red cell filterability (deformability) in leucocyte-free suspensions of washed erythrocytes is described. All equipment used is inexpensive and readily available. Polycarbonate membranes of 5 microns porosity are regenerated after each filtration. Consecutive filtration measurements allow for very good precision. The proposed method has high sensitivity for suspensions of overall slightly stiffened red cells or mixtures of normal and small numbers of greatly abnormal erythrocytes. In the latter case the method also fractionates. The method has been tested in vitro. Both human albumin solution and acetyl salicylic acid increased erythrocyte filterability. Chlorhexidine and silver sulphadiazine on the other hand adversely affected filterability. The technique is very suitable for the investigation of the effect of pharmacologically active materials on red cell filterability (deformability).

Burns↗
PubMed1986

Effects of hyperglycaemia and sorbitol accumulation on erythrocyte deformability in diabetes mellitus.

Erythrocyte deformability was studied in a total of 83 poorly controlled diabetics (mean blood glucose 12.2 mmol/l) who were divided into three groups, each with matched healthy controls. There was no appreciable difference between diabetics and matched controls regarding the filtration of erythrocytes through 3 micron diameter straight channel pores (25 diabetics) or tortuous channel pores (28 diabetics), or for the measurement of erythrocyte elongation over a range of osmolalities in the Ektacytometer (30 diabetics). When erythrocytes from 17 additional diabetics and 17 healthy controls were incubated for two hours at 37 degrees C in hyperglycaemic (50 mmol glucose/l) buffer, however, there was a considerable reduction in erythrocyte filterability for both diabetics and controls in parallel with an increase in erythrocyte sorbitol concentration. This loss of filterability was prevented by the addition of an aldose reductase inhibitor (Sorbinil). High glucose concentrations (congruent to 50 mmol/l) impair the filterability of erythrocytes through 3 micron pores, and the intracellular accumulation of sorbitol in poorly controlled outpatients is therefore unlikely to have a major adverse effect on erythrocyte rheology in diabetes mellitus.

Adult↗
PubMed1985

Erythrocyte deformability in peripheral occlusive arterial disease.

A rheological study of 32 patients with peripheral occlusive arterial disease (POAD), compared with 32 matched healthy controls, has shown no loss of erythrocyte deformability as measured by filtration methods (using initial flow rate and positive pressure instruments, polycarbonate and silver membranes, and 3 microns and 5 microns diameter pores) or by viscometry (using laser visco-diffractometric and high shear rate viscosity methods). Erythrocyte ATP concentration in POAD was also normal. Patients with POAD showed a small (4 fl) increase in mean erythrocyte volume, associated with a raised serum gamma-glutamyl transpeptidase concentration, which correlated with erythrocyte filtration and viscometric measurements. Previous reports of impaired blood filterability in POAD probably reflect the effects of accompanying leucocytosis, plasma hyperfibrinogenaemia, or an increase in erythrocyte size, but not an intrinsic loss of erythrocyte deformability.

Adenosine Triphosphate↗
PubMed1984

The concentration of plasma fibronectin in burns patients treated with fresh frozen plasma or plasma protein fraction.

A group of 10 patients with 30-70% burns were given intravenous infusions during the first 48 h following hospital admission either with fresh frozen plasma (FFP) or human plasma protein fraction ( HPPF ). FFP contained 300-400 mg/dl plasma fibronectin whereas none was detectable in HPPF . Circulating plasma fibronectin levels fell quickly in those patients receiving HPPF and levels remained low for 2-3 weeks. In those receiving FFP, plasma fibronectin remained normal during the 48-h transfusion period but fell subsequently. Fibronectin may be an important determinant in the resistance to shock and infections. Consideration should therefore be given to the use of blood products which contain fibronectin and to the monitoring of plasma levels both during the acute and recovery periods after burn injury.

Adolescent↗
PubMed1982

The effect of thermal injury on the loss of calcium from calcium loaded red cells: its relationship to red cell function and patient survival.

The loss of calcium from in vitro loaded red cells from burned patients was investigated and related to cell hydration, deformability and the intra-extracellular pH difference. Episodes of delayed calcium extrusion were evident in all patients and associated with low cell water and high intracellular calcium and sodium. The pH gradient decreased, although whole blood pH remained normal. These abnormalities were reversible. Surviving patients reverted to normal in about one week with very brief recurrences. Fatal burns remained abnormal much longer and reversal to normal was very brief. Calcium extrusion and intracellular cations were always abnormal before death. Frequent extensive blood transfusions favourably affected the red cell abnormalities. Persistent delayed extrusion of calcium from in vitro red cells indicates poor prognosis for recovery.

Adult↗
PubMed1982

The influence of catecholamines and prostaglandins on calcium efflux and filtrability of thermally damaged erythrocytes: an in vitro study.

Whole blood was heated in vitro and incubated with any of the following: epinephrine, norepinephrine, prostaglandin E1, prostaglandin E2 or prostaglandin F2 alpha. The treatment was assessed by whole-blood filtration and extrusion of a Ca2+ load from Ca2+ loaded red cells. Epinephrine did not affect the parameters measured. Norepinephrine increased cell filtration times and delayed Ca2+ extrusion. Prostaglandin E1 acted in an opposite manner. prostaglandin E2 and F2 alpha both decreased red-cell deformability and Ca2+ extrusion above the effect of heat alone Prostaglandin E2 showed the most pronounced effect. Possible implications of the findings for microcirculation in burned patients are discussed.

Alprostadil↗
PubMed1979

Water movement in red cells from burned patients. Its relationship to sodium retention and red cell filtrability.

Nine burned patients were investigated. Urinary sodium retention was associated with low red cell water and reduced red cell filtrability. The red cells from patients who recovered lost less water than normal cells when suspended in hypertonic NaCl solution but the proportionality of water loss or gain found for normal cells was maintained. The red cells from fatally burned patients lost proportional behaviour in hypertonic or hypotonic media. The abnormalities are not related to the area of the burn and may be the result of varying therapy. The monitoring of red cell water and water movement under tonicity stress is a convenient measure of the metabolic state of the cell.

Adolescent↗
PubMed1976

A convenient and reproducible filtration technique for the determination of erythrocyte flexibility.

A micro-cell filtration technique is described in which a silver membrane of 3 mum porosity is used. The apparatus consists of a membrane holder and disposable syringe only. A regeneration procedure which allows indefinite re-use of one membrane is described. Filtration proceeds under the hydrostatic pressure of the fluid column only. A locke-albumin solution has been developed as a suspension medium and adapted for cell washing by the addition of fibrinogen and cholesterol. A plot of the volumes of cells filtered against log time shows a linear relationship for normal erythrocytes. The filtered red cells are virtually undamaged. The overall precision of the method of the order of +/-2%.

Cell Membrane↗
PubMed1970

Thermal damage to red cells.

Erythrocytes from a burned patient show a temporal sequence of morphological changes. Immediate severe changes occur which are followed by a transient phase only of less abnormal morphology. Heating whole blood in vitro to 49 degrees C instead of 50 degrees C does not show the expected dose response curve. Heating whole blood in vitro to 50 degrees C induces progressive morphological changes. Fractionation of whole blood and subsequent heating to 48 degrees C show the older cells to be less deformable.

Burns↗
PubMed1967

Osmotic resistance of heat-damaged erythrocytes.

Whole blood was heated for twenty minutes at 40 degrees C., 45 degrees C., 50 degrees C., and 55 degrees C. Changes in the osmotic resistance of the heat-exposed cells were then determined. The values obtained were plotted as lysis increments. This treatment revealed groups of cells of varying heat sensitivity. After heating to 50 degrees C., cell groups were therefore prepared by partitioning cells between layers of a mixture of methyl- and butyl-phthalates of known densities. Three cell groups enriched in either oldest cells, cell fragments, or cell fragments and youngest cells were obtained. These groups subjected to serialosmotic lysis tests revealed that the densest, i.e., oldest fraction, had least thermal resistance. Fractionation and osmotic resistance studies provided clear evidence of some thermal damage to erythrocytes of median age, i.e., cells which would normally be expected to remain in the circulation for another two months. Some of the possible implications are discussed.

Erythrocyte Aging↗