Search

Information about several papers discussed at a meeting held at the Barnet General Hospital in London, England is presented. Some of the speakers of the event includes P. Gaehtgens, S. E. Lennie, J. G. Jones, and G. D. O. Lowe. Topics discussed at a meeting includes an overview about rheology, the use of micropore filtration and micropipette techniques, and the aspect of white cell behavior.

The article highlights a two-day meeting conducted by the Forum on Clinical Haemorheology on plasma factors and haemorheology in the neonate and the adult. The common cause of variations in the rheological properties of blood is said to be the influence of changes in the plasma environment. The mechanics of the neonatal red cells were discussed by professor O. Linderkamp.

Information about several papers discussed during the Forum on Clinical Haemorheology on April 12, 1985 is presented. The conference was devoted primarily to blood and plasma viscosity and their measurement. The event featured several speakers Arpad Matrai, A. C. Fisher, J. A. Evans and G. D. O. Lowe.

The reversible aggregation of red blood cells (RBC) into linear and three-dimensional structures continues to be of basic science and clinical interest: RBC aggregation affects low shear blood viscosity and microvascular flow dynamics, and can be markedly enhanced in several clinical states. Until fairly recently, most research efforts were focused on relations between suspending medium composition (i.e., protein levels, polymer type and concentration) and aggregate formation. However, there is now an increasing amount of experimental evidence indicating that RBC cellular properties can markedly affect aggregation, with the term "RBC aggregability" coined to describe the cell's intrinsic tendency to aggregate. Variations of aggregability can be large, with some changes of aggregation substantially greater than those resulting from pathologic states. The present review provides a brief overview of this topic, and includes such areas as donor-to-donor variations, polymer-plasma correlations, effects of RBC age, effects of enzymatic treatment, and current developments related to the mechanisms involved in RBC aggregation.

Transient plugging of microcapillaries by leucocytes is a possible reason for the occurrence of acute hypoxia in tumours. We compared the abilities of nicotinamide at 1000 micrograms ml-1 and 150 micrograms ml-1 and pentoxifylline at 300 micrograms ml-1 to increase the filterability of normal and artificially activated human leucocytes through 8 microns pores, as a model for the capillary bed. Using a St George's filtrometer, filterability of treated leucocyte suspensions was compared with control for three to six sequential 60 microliters samples, normalising control values to unity. Pentoxifylline at 300 micrograms ml-1 halved the ratio of treated to control value to 0.47 +/- 0.13 (2 s.e.), P = 0.001 (i.e. an increase in filterability), and nicotinamide at 1000 micrograms ml-1 reduced it to 0.69 +/- 0.22, P = 0.04, but the clinically achievable 150 micrograms ml-1 was ineffective (0.82 +/- 0.25, P = 0.24). Filterability of artificially activated leucocytes was reduced (3.9 +/- 1.20) but was restored to control values of unity by 1000 micrograms ml-1 nicotinamide and 300 micrograms ml-1 pentoxifylline and partially restored by 150 micrograms ml-1 nicotinamide (1.2 mM), which was isoeffective with 100 micrograms ml-1 pentoxifylline (0.37 mM). Pentoxifylline is therefore more effective on a molar basis and was shown to affect both polymorphonuclear leucocytes and lymphocytes, while nicotinamide only affects lymphocytes. The data are consistent with the hypothesis that both agents modify acute hypoxia by increasing leucocyte filterability.

The effect of dextrans of various molecular weights on the solubility of fibrinogen was investigated. The results indicate that the prime effect responsible for the observed changes of solubility was steric exclusion. This applies over the whole molecular-weight range of dextrans used, i.e. from 5700 to 76000.