PubMed Health⌕ Search

Biomedical subjects

M Hanss

Publications and source records attributed to M Hanss.

At least 37 records · Page 2Linked to original sources
PubMed1985

Aspirin, indomethacin and dazoxiben do not affect the fibrinolytic activation induced by venous occlusion.

A cause-effect relation between the synthesis and release of prostaglandins and fibrinolytic activation has been suggested. We have reinvestigated this relation in a double-blind, placebo-controlled, cross-over study with cyclooxygenase inhibitors (aspirin and indomethacin) and a thromboxane synthase inhibitor (dazoxiben) in nine healthy volunteers. Euglobulin fibrinolytic activity (EFA) and tissue-type plasminogen activator antigen level (t-PA:Ag) were studied before and after 10 min of venous occlusion. Despite effective suppression of prostaglandin synthesis by aspirin and indomethacin and enhanced prostacyclin formation by dazoxiben, baseline EFA and t-PA:Ag levels did not significantly change within 2 hours after ingestion of the different drugs. The release of t-PA by venous occlusion was not altered by any of the drugs. Thus, our study does not support the hypothesis that prostaglandins play a significant role in the modulation of the synthesis or release of t-PA.

Aspirin↗
PubMed1985

Physico-chemical factors of erythrocyte deformability.

The aim of this study is to assess the role of different physico-chemical factors on the deformability measurements by using the initial filtration flow rate method, and to differentiate between the membrane or internal origin of some rigidity changes. The deformability is maximum for the physiological pH value and it decreases sharply for hypotonic and hypertonic buffer. For normal RBC, the deformability is independent of the pO2 level and a small decrease is observed for increasing pCO2 values (with constant pH). A theoretical model of filtration for the "Hemorheometre" will be also developed.

Carbon Dioxide↗
PubMed1984

Thermal transitions of red blood cell deformability. Correlation with membrane rheological properties.

Red blood cell deformability has been studied by the initial filtration flow rate as a function of temperature. The well-known transition at 49-50 degrees C (probably due to spectrin denaturation) is shown. Another transition is demonstrated around 18 degrees C (the cell becomes stiffer below this temperature range). The erythrocyte membranes prepared by a mild dialysis technique have the same deformability as intact erythrocytes at room temperature; they also show the same low-temperature transition. No such transition has been found for hemoglobin solutions of viscosity 30 g X dl-1. It is interesting to compare these results with those obtained by other methods which measure the properties of natural or artificial lipid membranes and which also demonstrate a thermal transition at 15-20 degrees C. Therefore, the deformability of intact normal erythrocytes seems to depend mainly on the rheological properties of the membrane.

Erythrocyte Membrane↗
PubMed1983

[Erythrocyte filtrability in liver cirrhosis].

In view of the frequent erythrocyte abnormalities found in liver cirrhosis, erythrocyte deformability was studied in 62 patients. Deformability was determined by the initial filtration flow technique using a Hemorheometer. Results are given as a rigidity index (IR), which is characteristic of the average individual RBC. Deformability was significantly reduced in patients with cirrhosis. No correlation was found with the often increased MCV. A significant positive correlation was found between IR and the cell membrane free cholesterol/phospholipid ration, as the increase in cell rigidity is mainly due to a decrease in the cell membrane sphingomyelin content. The role of reduced RBC deformability in liver cirrhosis anemia still awaits elucidation.

Erythrocyte Indices↗
PubMed1983

Erythrocyte filtrability measurement by the initial flow rate method.

A new filtration technique, based on the initial filtration rate of a diluted RBC suspension through 5 mu Nucleopore filter is described. As only a few hundreds RBCs traverse each pore and as the measurement are made in a few seconds, the method is by large insensitive to filter plugging and to sedimentation effects. The results are given as a filtration index IF which is, as a first order approximation, independent of the filter conductance and of the suspending medium viscosity. The filtration times are measured electronically. The filters are re-used many times. The influence on the results reproducibility of RBC washing, of the anticoagulant, of the blood sample and the suspension storage times are considered. With our technical procedure, the relative incertitude on the measurement of I.F. is about +/- 10%. The filtration index is shown to be an intrinsic RBC filterability property.

Blood Viscosity↗
PubMed1983

Indices of filterability of red blood cell suspensions.

A number of different experimental techniques have been devised in recent years to use microsieving as a test of the filterability of suspensions of red blood cells. Various indices have been proposed to express the results of these tests. In the present paper a correlation is made of the intrinsic increase in resistance at the level of a single pore in the filter to the macroscopically observed pressure and flow through the entire filter. Further it is shown how a number of different tests may be used to derive the same index. The results apply only to situations in which there is no plugging of pores.

Erythrocytes↗
PubMed1983

Determination of erythrocytes transit times through a 5 mu "nuclepore" filter.

Filtration experiments through 5 or 3 mu Nuclepore membranes are often performed in order to assess the so-called erythrocyte deformability. The relation between this parameter and the RBC filterability is not straightforward. A simple theoretical treatment relating filtration index (as determined by the initial flow rate method) to the average RBC flow resistance through an average pore is presented. In order to deduce the average RBC transit time through the membrane from the initial flow rate data, the suspension hematocrit change after filtration has been determined. The calculated average transit time is comparable to experimental values, as determined by KIESEWETTER et al. with the single pore technique.

Erythrocytes↗
PubMed1982

[Use of a new rheometer for the study of the filtrability of a suspension of sickled red cells as a function of PO2].

The filtration time of a small volume (0.1 ml) of red cell suspension from normal (AA), heterozygous (AS) and homozygous (SS) subjects for sickle cell disease was investigated as a function of PO2 The curve of filtration time of AS and SS red cell suspensions was biphasic. At high values of PO2, the progressive reduction of filtrability of sickle cell suspensions with decreasing PO2 occurred without new change in morphology of most of the cells. In contrast, at lower PO2 the apparent filtrability was improved and the cells were sickled." However the red blood cells were retained by the filter and the "solvent" filtrability was improved because rigid and highly deformed sickled cells did not clogged completely the pores of the filter. This study allowed to distinguish a new concept of apparent filtrability for red blood cells in sickle cell disease.

Anemia, Sickle Cell↗
PubMed1980

Conductimetric study of the binding of Mn2+ to bovine pancreatic deoxyribonuclease.

The binding of Mn2+ on bovine pancreatic deoxyribonuclease has been studied by a conductimetric method. At low ionic strengths, a high-affinity single binding site is demonstrated. The association constant value (K = 1.2 x 10(5) M-1 at pH 8) is high enough to conclude that, in standard experimental conditions for DNA hydrolysis, the reacting species is the DNAase-cation complex. Competitive binding studies in presence of Mg++ and Ca++ show that these cations do not bind on the Mn++ site.

Animals↗
PubMed1977

[Conductometric microdosage of blood and urine urea by use of a semi-automatic analyser].

The authors present the principle of a new method of urea estimation based on conductimetry. Its results are compared with those given by the colorimetric method using diacetylmonoxime. Correlation of the results was satisfactory. With the apparatus studied, it was possible to estimate very simply plasma and urinary urea with low volume samples 10 microliter). The titration took 30 seconds.

Autoanalysis↗