PubMed Health⌕ Search

Biomedical subjects

J F Stoltz

Publications and source records attributed to J F Stoltz.

At least 127 records · Page 7Linked to original sources
PubMed1990

[Development of a technique of immunoadsorption of LDL-cholesterol].

An immunoadsorption system for lowering plasma cholesterol was optimized. Several polyclonal and monoclonal antibodies were compared and the best results were obtained with goat polyclonal antibodies. The optimum quantity of antibodies to be immobilized on the gel was 5 mg/ml. Taking into account two variables, i.e., 1) that the regeneration must be as complete as possible and, 2) that immunoadsorbents must be used several times without a loss of adsorption capacity, desorption was achieved with 0.3 M glycine adjusted to pH 2.8. Antibody release from the immunoadsorbent was determined and can be minimized by glutaraldehyde treatment of the immunoadsorbent. Each phase, adsorption and desorption, respectively, was well-defined and synchronized, so that two columns could be used in parallel in an automated procedure. The kinetics of plasma protein removal demonstrated the efficiency and the specificity of the procedure.

Animals↗
PubMed1990

[Value and study methods of hemorheology in vascular pathology and pharmacology].

The growth of modern, reliable, reproducible and relatively inexpensive techniques of studying micro and macrorheological changes has confirmed the role of haemorheology in the physiology of the microcirculation and the consequences of its disturbance in vascular and ischemic pathology. These abnormalities can be corrected by pharmacological agents including several vasoactive molecules which owe at least some of their therapeutic effects to their action on blood rheology especially on the red blood cells. Systematic study of the rheological effects of these vasoactive, anti-ischemic substances is now possible and necessary.

Blood Physiological Phenomena↗
PubMed1990

Study of parameters involved in specific immunoadsorption of apolipoprotein B.

A therapeutic immunoadsorption system on immobilized and anti-apolipoprotein B as a plasma cholesterol lowering procedure was optimized. Several antibodies were compared and highest adsorption capacity was obtained with goat polyclonal antibodies. Optimum quantities of antibodies to be immobilized on the gel and quantities of apo-B to be applied to columns were determined. The amount of antibodies released from immunoadsorbents can be minimized by treatment with a 0.005% glutaraldehyde solution with an acceptable reduction rate of adsorption capacity. Each phase, adsorption and desorption respectively, were well-defined and synchronized so two columns could be used in parallel in an automated procedure. In these conditions, the immunoadsorption system can efficiently, specifically and safely remove cholesterol and has to be subjected to clinical trials.

Animals↗
PubMed1990

[Importance of membrane fluidity determination].

Translational motions of lipids and proteins and molecular motions within the lipid hydrocarbon chains of biological membranes can be approached by spectroscopic methods. The electron spin resonance (ESR) spectra of spin labels bound on proteins or grafted on fatty acids and incorporated into biological membranes undergo characteristic changes which may be resolved in terms of modifications of membrane environment. However, the method is still scarcely used in routine clinical studies. In contrast, fluorescence methods such as intermolecular excimers or fluorescence polarization might join the ranks of routine analyses. The labeling of lipid compartments with fluorescent probes and the study of their spectroscopic properties give informations on the cohesion of their immediate environment. Polyenic molecules (DPH and TMA-DPH) which are located in different lipid compartments characterize deep and superficial areas of cell membrane, respectively. A set of probes in which a 9-anthroyloxy group is attached to different positions of a long chain fatty acid provides a means of measuring a fluidity gradient into membrane bilayer. Thus, these fluorescence methods which are simple and rapid represent a semi-quantitative approach of the so called "membrane fluidity". Modifications in membrane fluidity can control the expression of proteins, receptors exposed on cell surface and alter functional properties of cells. Moreover, pathological processes can also be related to fluidity modifications. In particular, in hypertension and vascular diseases, a decrease in membrane fluidity has been shown in platelets and red cells. Nevertheless, further investigations combining biophysical, biochemical and immunological methods are needed to determine the exact relations between membrane fluidity, classical rheological properties and cell functions.

Biophysical Phenomena↗
PubMed1989

Phagocytosis and membrane fluidity: application to the evaluation of opsonizing properties of fibronectin.

The uptake of particles by phagocytic cells involves an increase in the membrane fluidity determined by steady-state fluorescence polarization. Binding and endocytosis of target particles is in vivo enhanced by humoral factors called opsonins. In this work, fluorescence polarization was used to detect in vitro the opsonic activity of a plasma protein: fibronectin. The assay is based on the analysis of membrane fluidity variations following the uptake of gelatinized latex beads by phagocytic cells in the presence or in the absence of fibronectin. Using TMA-DPH as fluorescent probe, it was observed that the increase in membrane fluidity was enhanced in presence of fibronectin and depended upon the enhanced in presence of fibronectin and depended upon the opsonic activity was related to the integrity of the molecule. Using this method, the opsonic activity of various plasmas could be also determined.

Cell Line↗
PubMed1989

Biotechnology of plasma proteins. Fractionation and applications.

Without discussing all of the current problems of industrial plasma fractionation, this INSERM International Symposium emphasized the importance of the technological progress of the last ten years. Although Cohn's classical technique of alcohol precipitation is still the most widely used, new techniques are rapidly being developed based on more selective methods with high extraction yields. However, it is certain that, given the growth in biotechnologies with the industrial applications of genetic engineering and cellular engineering, various problems will eventually be raised concerning plasma fractionation. It is probable that in the relatively near future certain fractions such as F VIII will no longer be prepared from plasma; but can the other fractions be reasonably replaced in the foreseeable future? Furthermore, the problems of purification will always be the crux of the development of biotechnologies. The technical committee of the OECD has recently drawn the attention of European governments to the considerable importance for the future of bioindustries of 'downstream processings' and the need to develop research on methods of extraction and purification. Human plasma is certainly the ideal model for the development of new methods of protein purification which could subsequently be applied to other industrial fields such as cellular engineering or genetic engineering. European countries definitely have an edge in this field as a result of their industries and fractionation centers.

Biotechnology↗
PubMed1989

[Cell cycle analysis of hybridoma cultures: study by cytofluorimetry].

An hybridoma cell line cultivated in flasks has been used as a model to study the loss of cell viability in high density cell cultures. Cell cycle analysis by cytofluorimetry has shown that a new hypochromosomic cell population appeared as soon as the viability began to decrease. However there is no evidence that this new population is constituted of dead cells.

Animals↗
PubMed1989

[Hemorheology, hemodynamics and microcirculation. 1].

The microcirculation constitutes an ubiquitous vascular network presenting a mesh pattern, and comprising different types of vessels, arterioles, small veins, capillaries, arteriovenous shunts or similar structures, and lymphatics. Many dimensions have to be recognized, or simply mentioned, if one is to understand the hemodynamic and hemorheological particulars of this territory, which differ, in many aspects, from those specific to the macrocirculation (number and length of the vessels, diameter and cross section, intercapillary distance, geometric characteristics, intravascular pressure, pressure gradient, pressure-volume relationship, flow rate, mean velocity of plasma and RBC, velocity profile, local hematocrit, in situ viscosity, kinematic viscosity, wall shearing conditions, local oxygen transport, aggregation and deformability of RBC, leukocyte properties, etc.). The flow rate in capillary tubes and capillary vessels of the living organism varies with many factors, such as proximal hemodynamics, hemorheological characteristics of blood (fibrinogen, macro- and micro-hematocrit), some known effects (Farheus, Farheus Lindqvist), local diameter, the plasma layer which plays the role of the limiting layer, the endothelial film, the wall effect, and so forth. Models of the circulation have been propounded, none of which takes into account the whole of these phenomena due to their great complexity. Hemodynamic and hemorheological interactions provide for a better understanding of certain concepts, such as vascular resistance, hindrance, capacitance, local flow rates, real capillary opening and closing, development of two-directional functional shunts, autoregulation, pressure-volume relationship, critical closing pressure, circulatory current slowing effect, sequelae of intravascular aggregation of formed blood elements.

Hemodynamics↗
PubMed1989

[Rheologic particulars of venous flow. Physiopathologic consequences].

Hemorheological parameters must be taken into account for a better knowledge of venous flow properties. The postcapillary venules are the region of lowest shear rates and therefore the region of highest whole blood viscosity. Red cell aggregation plays a major role in blood viscosity, especially at low shear rate. This microrheological parameter can be increased in pathological circumstances, including a low capillary flow, venular insufficiency, elevated hematocrit, high levels of acute phase proteins. At the level of the capillaries, microcirculatory stasis leads to a low oxygen supply and consequently to poor metabolic state lowering local ATP levels. As a result, both platelet and white blood cell functions are compromised. Hemorheological studies have shown that both deep venous thrombosis and chronic venous insufficiency are associated with high blood viscosity mainly due to an increased red cell aggregation. This hemorheological vicious circle--stasis promoting hyperviscosity leading to further stasis--could be broken up by therapeutic intervention including hemodilution, fibrinolytic drugs or other specific agents.

Blood Circulation↗
PubMed1988

Affinity purification of human plasma fibronectin on immobilized gelatin.

Several problems are associated with the biospecific affinity purification of plasma fibronectin on gelatin-Sepharose. Large-scale development of this purification procedure requires optimization of adsorption and elution conditions. The adsorption capacity depends on the amount of gelatin coupled to the Sepharose, the residence time, the temperature and the amount of fibronectin loaded on the adsorbent. Elution of adsorbed fibronectin with 3 M urea leads to incomplete recovery. The elution yield was found to vary with both the gelatin concentration and the amount of adsorbed fibronectin. Despite the incomplete elution, the adsorption capacity did not decrease after twelve consecutive isolation procedures. Under optimized conditions, the method described here provides a rapid, single-step and convenient way for the isolation of pure and functional fibronectin, either for analytical or large-scale preparative purposes.

Adsorption↗
PubMed1988

[Highly purified, functionally active human fibronectin preparation].

Fibronectin has been purified by gelatin-Sepharose affinity chromatography from fresh frozen human plasma. The bound fibronectin was eluted with 3 M urea. The purity of the fibronectin obtained has been checked on (immunoelectrophoresis, polyacrylamide gel electrophoresis, FPLC). Biological activity of the purified molecule has been monitored by means of three assays: quantitation of the gelatin-binding activity by ELISA, quantitation of the fibronectin-mediated attachment of fibroblasts on plastic and evaluation of the opsonic activity (uptake of gelatin latex particles by a murine macrophage line). When deep-frozen, fibronectin retains all of its properties. This highly purified and functional fibronectin fulfills the basic requirements for a standard reagent. It will allow to investigate physicochemical and functional alterations of various fibronectins.

Cell Adhesion↗
PubMed1988

Erythrocyte aggregation: approach by light scattering determination.

Erythro-aggregometer is a Couette viscometer which was developed to measure aggregation parameters of red blood cells. The system is based on the analysis of the light intensity backscattered by a blood suspension. It allows to approach aggregation phenomenon in terms of kinetics, structural and rheological parameters. The measurement system designed for use with a microcomputer is suitable for both research and clinical investigations.

Blood Viscosity↗
PubMed1988

Haemorheological abnormalities in arterial hypertension and their relation to cardiac hypertrophy.

Haemorheological characteristics were measured in a group of 52 patients with essential arterial hypertension (HT), and were compared with those of a group of normotensive subjects. The relationships between the arterial blood pressure (BP), the echocardiographic indices of left ventricular hypertrophy (LVH), and the haemorheological measurements, were studied. The group of hypertensive patients was found to have a hyperviscosity syndrome with significant elevations of blood viscosity at all shear rates (for gamma = 0.20/s, 29.6 +/- 0.6 versus 28.0 +/- 0.3 mPa.s, P less than 0.01: for gamma = 128/s, 4.2 +/- 0.05 versus 4.1 +/- 0.02 mPa.s, P less than 0.02, of plasma viscosity (1.29 +/- 0.01 versus 1.22 +/- 0.06 cSt, P less than 0.001); of erythrocyte aggregation index (17.8 +/- 0.06 versus 14.6 +/- 0.4, P less than 0.001); of erythrocyte filterability index (13.3 +/- 0.5 versus 8.8 +/- 0.2, P less than 0.001) and plasma fibrinogen level (3.4 +/- 0.9 versus 2.8 +/- 0.6 g/l, P less than 0.02). The haematocrit did not differ from that of normotensive subjects (43.3 +/- 0.6 versus 44.7 +/- 0.5%, NS). The left ventricular mass was increased and was positively correlated with the blood viscosity at a high shear rate (r = 0.38, P less than 0.01) and with the erythrocyte aggregation index (r = 0.47, P less than 0.01). Systolic, diastolic, and mean arterial blood pressures were positively correlated with the left ventricular mass (r = 0.34-0.47, P less than 0.05) and with the erythrocyte aggregation index (r = 0.42-0.46, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Immunosorption of apolipoproteins B. Optimization of the method in an in vitro bench test].

The aim of the present study was to determine optimum conditions for preparation and use of immunoadsorbents for removal of apolipoprotein B from plasma. An in vitro study was carried out to optimize different chromatography parameters: linear flow rate, apo B quantity loaded, gel regeneration conditions. Specificity of removal of apo B, stability of antibody covalent linkage and possible multiple use of immunoadsorbents were assessed. No significant loss of adsorption capacity was observed after sterilization and storage of immunoadsorbents.

Apolipoproteins B↗
PubMed1987

[Effects of intravenous nicardipine on blood pressure, hemorheology platelet function in arterial hypertension. Dose-effect relations].

In arterial hypertension, hyperviscosity with hemorheological disturbances and platelet dysfunction may play a role in the prognosis and complications of the disease. We studied the effects of Nicardipine (NIC) on these blood disturbances in a group of 21 untreated patients with essential hypertension, aged 25 to 70 years (SBP/DBP = 185 +/- 28/105 +/- 17 mmHg). During one hour before and 4 hours after the IV injection of single doses of 5, 7.5 or 10 mg NIC over 5 min, blood pressure was recorded automatically (Dinamap). Hemorheological variables and platelet function were studied before and 30 min, 3 h and 24 hours after the injection. NIC lowered blood pressure and increased heart rate significantly (At 5 min, SBP = -24 mmHg; DBP = -18 mmHg; HR = +22 b/min). These effects were dose-dependent with rapid onset and short duration (less than 2 hrs). NIC decreased plasma viscosity from 1.36 +/- 0.08 to 1.30 +/- 0.07 Cst; p less than 0.01, whole blood viscosity from 22.4 +/- 2.8 to 20.7 +/- 1.5 mPas; p less than 0.05 for gamma = 0.512 s-1, and erythrocyte filterability with the Ca++ ionophore A 23187 from 16.3 +/- 3.8 to 13.5 +/- 3.1; p less than 0.01. Platelet aggregation with ADP was unchanged, but aggregation with A 23187 decreased from 46.9 +/- 21.2 to 31.3 +/- 25.6; p less than 0.05, as well as plasma levels of beta-thromboglobulin (71.2 +/- 29.8 to 55.4 +/- 24.3 ng/ml; p less than 0.02) and platelet generated malonaldehyde (7.2 +/- 1.8 to 6.7 +/- 1.4 nM/10(9) platelets; NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗