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Biomedical subjects

S Gaillard

Publications and source records attributed to S Gaillard.

At least 73 records · Page 4Linked to original sources

Ehlers-Danlos syndrome, clotting disorders and muscular dystrophy.

Ehlers-Danlos syndrome includes 11 distinct entities. The diversity of this collagen dysplasia and its combination with other abnormalities make it difficult to understand physiopathologically. A case of Ehlers-Danlos syndrome is reported, which is novel owing to its combination with clotting abnormalities and especially with muscular dystrophy. To our knowledge this has not previously been reported. The patient was a young man aged 16 years who presented with Ehlers-Danlos syndrome satisfying Perelman's diagnostic criteria. His father and two brothers had comparable clinical symptoms, but his mother and sister were healthy. The four male subjects had an increased cephalin-kaolin time, reduced levels of factor VIII and Willebrand's factor (but without haemophilia A or Willebrand's disease), and, especially, an abnormal platelet ATP secretion. The proband alone had muscular disease with bilateral quadriceps fatigability and amyotrophy. The muscle enzyme levels were greatly increased, the electromyographic trace was myogenic, and the biopsy showed severe muscular dystrophy. This new observation poses the problem of the relation between clotting abnormalities and collagen abnormalities in the Ehlers-Danlos syndrome. It is difficult to classify this case within any of the 11 known types because of its muscular manifestations. It may perhaps be a fortuitous combination or an extension of the nosological framework of this syndrome.

Adenosine Triphosphate↗

Survey of the folding pathway of a two-domain protein phosphoglycerate kinase.

The role of structural domains as folding units in the folding process which generates an active enzyme, is considered through several studies on phosphoglycerate kinase, a two-domain enzyme which catalyzes the first step of ATP production in glycolysis. The folding pathway was found to be a complex multi-step process, the C-terminal domain being more stable folding first. Inactive species originating from an intermediate in the folding pathway have been identified. Isolated domains recently obtained using genetic engineering are under investigation in our laboratory; this might probably allow to understand the way by which the N-terminal domain reaches its final native conformation and interacts with the other domain.

Animals↗

[Hemorrheological changes in 50 monoclonal dysglobulinemias treated by plasma exchange].

Rheological examinations were performed before and after plasma exchanges in 50 patients with monoclonal dysglobulinaemia. The parameters investigated were blood and plasma viscosity, erythrocyte filtrability, erythrocyte aggregation and kinetics of agglutination. The results showed reduction of blood and plasma viscosity and improvement in agglutination kinetics under plasma exchanges. Rheological examinations therefore seem to be useful to follow up blood disorders, notably the hyperviscosity syndrome. They can be performed prophylactically, leading to early plasma exchanges to prevent clinical deterioration.

Blood Viscosity↗

[Blood T lymphocyte populations in the hemophiliac].

We have studied a group of 31 hemophiliac patients (hemophilia A: 26 patients, hemophilia B: 5 patients); 29 healthy men were used as controls. Hemophiliac patients had increased percentages of suppressor T-lymphocytes and depressed T4/T8 ratios. These abnormalities were found to be significantly correlated with the amount of F VIII used per year.

Adolescent↗

Experimental approach to rouleau formation. Comparison of three methods.

From a clinical point of view, the approach to erythrocyte aggregate or rouleau formation and cohesion is undeniably of great interest. A large number of methods have been suggested for studying this parameter such as: back-scattering of light, nephelometry, ultrasound, etc... In this paper the authors have compared three methods to approach rouleau formation: direct observation of rouleau formation (rheoscope); 'erythrocyte aggregometer': with this technique, the light transmitted by the sample is integrated over a period of time and provides an index (IA); laser reflectometer based on studying the light that is back-scattered by the blood sheared in the gap of a viscometer. The results show that the indexes measured by both reflexion and transmission vary according to hematocrit and reach a maximum value at hematocrit levels of between 30 and 40%. In contrast, observation using the rheoscope did not provide qualitative evidence of this phenomenon.

Blood Viscosity↗

Investigation of human blood platelets with fluorescence spectroscopy.

Intramolecular excimer formation of dipyrenylpropane was investigated in human blood platelets. The ratio of the emission intensities of excimer to monomer (IE/IM) is sensitive to changes in lipidic membrane structure, induced by external perturbations, such as cholesteryl hemisuccinate introduction and temperature. Lack of reliable "microviscosities" determinations could be due to poor solubility of the probe in aqueous cells suspensions. Results were compared to those obtained with the fluorescence polarization technique.

Blood Platelets↗

[Atypical osteodystrophy of visceral origin (author's transl)].

The authors report a case of atypical osteodystrophy of visceral origin (uretero-sigmoid by-pass for bladder exstrophy) which was characterized by the association of osteocondensation and looser-Milkman lines. They emphasize the rareness of osteodystrophy after uro-digestive by-pass and the exceptional character of the osteocondensation.

Acidosis↗

Hemorheological and biochemical parameters in the "fatty" rat.

The essential part played by rheological factors in genesis of thrombosis and atherosclerosis has often been mentioned. Thus the authors have carried out a study of rheological and biochemical parameters on a genetic animal model with modifications in plasma lipids (homozygous obese "Fatty" rat) compared to the non obese heterozygous animal. The results obtained for the evolution of biochemical parameters (blood glucose, cholesterol, triglycerides) over a 16 months period confirm those published earlier. Further, a significant increase in fibrinogen level was observed in homozygous animals, and correlated with plasma viscosity. There results are also connected with changes in apparent blood viscosity which is considerably increased in homozygous rats, particularly at low shear rates (gamma less than 20 s-1). These results show the value of this animal model and the authors suggest the application of such a genetic animal model and of its heterozygous control population to both theoretical rheological and pharmacological studies on atherogenesis and hyperlipoproteinaemia.

Animals↗

[Influence of metabolic control on blood viscosity and platelet activity in insulin requiring diabetics].

Blood and plasma viscosities were determined using respectively a Couette type micro-viscometer (LS 30) and an automatic capillary viscometer (FICA). Plasma beta-thromboglobulin (beta-TG) levels were determined by radioimmunoassay. These parameters were measured in a group of 11 poorly controlled insulin requiring diabetics before and after blood glucose normalization using an artificial pancreas (Biostator GCIIS). Before connection to the artificial pancreas, blood and plasma viscosity and beta-TG levels were significantly higher in diabetics than in controls. The strict metabolic control obtained by the artificial pancreas resulted in a normalization of the hemorheological parameters and in a significant reduction of plasma beta-TG levels after 48 h. These results suggest that the metabolic control of diabetes influences the rheological behavior of blood and the metabolism of platelets.

Adolescent↗

[Blood viscosity. Measurement and applications (hyper--and hypoviscosity syndromes) (author's transl)].

Blood has particular rheological properties which partly condition its flow, especially in capillary vessels, and its ability to deliver oxygen. It is not subject to gravitation, pseudoplastic, thixotropic and visco-elastic. Blood viscosity depends upon macroscopic factors, such as erythrocyte aggregation and deformability. Hyperviscosity is observed in cases of increased haematocrit (polycythaemia and relative polycythaemia), increased serum proteins and changes in protein balance (e.g. rise in fibrinogen and immunoglobulins, fall in albumin) as seen in inflammation and dysglobulinaemia, drop in temperature (hypothermia), increased erythrocyte aggregation (shock, fat embolism) or imparied deformability due to various acquired or inherited disorders of red cell membrane or cytoplasma (e.g. sickle cell anaemia, renal failure, hyperlipoproteinaemias, thrombosis, diabetes). The various factors may be combined, as in diabetes. Conversely, hypoviscosity may result from decreased haematocrite, fall in blood proteins and fibrinogen, or hyperthermia. Hyperviscosity can be corrected by acting on its various constituents. Treatments include haemodilution, plasmapheresis, anti-aggregants and drugs improving red cell deformability.

Blood Proteins↗

Plasma viscosity and biochemical parameters in the "fatty" rat.

The essential part played by rheological factors in the genesis of thrombosis and atherosclerosis has often been mentioned. Thus, we undertook an investigation on plasmatic rheological factors in an animal model with modifications in plasma lipids (homozygotic and heterozygotic "fatty" rats) compared to normal animals (Sprague-Dawley rats). Test parameters were: cholesterol, triglycerides, lipidograms, glucose, total proteins, fibrinogen, plasmatic viscosity. Experiments gave the following results in homozygotic animals as compared to heterozygotic rats and controls: hyperlipidemia with massive increase in triglycerides, hyperfibrinogenemia, increase in total proteins and glucose, modifications in lipidogram in the form of more lipoproteins migrating in the beta-position and fewer proteins migrating in the alpha-position. Such changes were accompanied by an increase in whole blood and plasma viscosity. After considering the various correlations between these parameters, the authors suggest the application of such an animal model to atherogenesis.

Animals↗