Biomedical subjects

C Bucherer

Publications and source records attributed to C Bucherer.

5 recordsLinked to original sources

PubMed1992

[Raynaud's phenomenon and blood viscosity].

Raynaud's phenomenon is mainly linked with cold provoked vasomotor perturbations, but also with rheological alterations since blood viscosity is enhanced by lowering temperature. Several methods are available for studying distal vascularization: peri-ungual capillaroscopy, digital plethysmography and laser-Doppler. Digital arteriography must be reserved to serious ischemia regarding the general anesthesia needed to avoid spasm. All these methods explore especially the vessel wall. Conservely, blood viscosity which has been developed for 25 years investigates the content of the vessel. Since 1965, numerous hemorheological studies pointed out the rheological disorders, especially those concerning plasma and blood viscosity. The most usual viscometry abnormalities revealed erythrocyte hyperaggregation, red cell hypodeformability, blood and plasmatic hyperviscosity. In a comparative study, 46 patients with Raynaud's phenomenon were studied: we performed peri-ungual capillaroscopy, plethysmography and viscosity measurements. The results demonstrated a link between capillaroscopy and thixotropy. Both investigations are never normal at the same time in connectivites and never abnormal at the same time in Raynaud's disease (primary Raynaud's phenomenon). In conclusion hemorheological studies showed nearly normal rheological parameters in Raynaud's disease, but abnormal rheological parameters in secondary Raynaud's phenomenon.

Adult↗

PubMed1991

[Hemorheologic effects following ergometric-controlled physical exercise].

In collaboration with the Laboratory of Physiology, the Unity of Biorheology realized hemorheological studies on healthy volunteers who performed four kinds of well-controlled exercises on a cycle ergometer. Blood was always collected just before exercise and just after exercise. Rheological measurements were performed (blood and plasma viscosities, blood thixotropy and blood viscoelasticity) as well as biological (plasma proteins) and biophysical (osmolarity, pH) measurements. In all the cases, results show the importance of a hemoconcentration and its hemorheology consequences.

Blood Viscosity↗

PubMed1978

Expansion and apparent fluidity decrease of nuclear membranes induced by low Ca/Mg. Modulation of nuclear membrane lipid fluidity by the membrane-associated nuclear matrix proteins?

Macronuclei isolated from Tetrahymena are contracted in form (average diameter: 10.2 micron) at a final Ca/Mg (3:2)concentration of 5 mM. Lowering the ion concentration to 1 mM induces an expansion of the average nuclear diameter to 12.2 micron. Both contracted and expanded nuclei are surrounded by a largely intact nuclear envelope as revealed by thin-sectioning electron microscopy. Nuclear swelling is accompanied by an expansion of the nuclear envelope as indicated by the decrease in the frequency of nuclear pore complexes from 52.6 to 42.1 pores/micron2 determined by freeze-etch electron microscopy. Contracted nuclear membranes reveal particle-devoid areas (average size: 0.21 micron2) on 59% of their fracture faces at the optimal growth temperature of 28 degrees C. About three-fifths of the number of these smooth areas disappear upon nuclear membrane expansion. Electron spin resonance using 5-doxylstearic acid as a spin label indicates a higher lipid fluidity in contracted than in expa,ded nuclear membranes. Moreover, a thermotropic lipid clustering occurs at approximately 17 degrees C only in expanded nuclear membranes. In contrast to the nuclear membrane-bound lipids, free lipids extracted from the nuclei rigidify with increasing Ca/Mg concentrations. Our findings are compatible with the view that the peripheral layer of the fundamental nuclear protein-framework, the so-called nuclear matrix, can modulate, inter alia, the lipid distribution and fluidity, respectively, in nuclear membranes. We suggest that a contraction of the nuclear matrix's peripheral layer induces a contraction of the nuclear membranes which, in turn, leads to an isothermic lateral lipid segregation within nuclear membranes.

Animals↗

PubMedDate not supplied

Relevance of measuring red blood cell disaggregability in insulin-dependent diabetic patients.

A viscometric study of blood from insulin-treated diabetic patients is carried out. Patients are divided into three major groups--group I: without or with minimal retinopathy and recent diabetes (n = 37), group II: without or with minimal retinopathy and at least 20 years of diabetes duration (n = 35), group III: with severe retinopathy (n = 27). Each group is also subdivided according to the glycosylated hemoglobin (HbA1c) level, used to assess long-term glycemic control. Finally, the rheological parameters of six groups are compared: three of which have a HbA1c level less than 7.5% [I1 (n = 15), II1 (n = 9), III1 (n = 9)] and three others have a HbA1c level more than 7.5% [I2 (n = 22), II2 (n = 26), III2 (n = 18)]. The most important result concerns the thixotropy index xi t, which reflects the dynamic property of red blood cell (RBC) disaggregability under shear. Strong correlations between this parameter and HbA1c level are found for groups I (r = -0.53, p < 0.001) and III (r = -0.68, p < 0.001), providing evidence of a RBC disaggregability disorder for a poor glycemic control of diabetes. In contrast, such a correlation is not pointed out for the group II. As the value for xi t is not statistically different for groups II1 and II2 and is close to the normal value in both groups, the existence of a rheological protection against the retinopathy could be involved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Activity of Daflon 500 mg on the hemorheological disorders in diabetes.

A rheological study was performed on blood samples from 10 insulin-treated diabetics with retinopathy. As part of their treatment, they all received 4 tablets of Daflon 500 mg per day for 30 days. Three complementary rheological criteria were used to characterize blood samples: 1) viscometry, using a Couette viscometer, which produces data on viscosity, shear-thinning, viscoelasticity and tixotropy of blood, 2) aggregametry, using an apparatus based on light reflectometry, using a filtrometer based on the deformations red cells undergo as they pass through narrow pores which produces information on red cell deformability. The main results were: a better red blood cell disaggregability, a decrease in red blood cell aggregation and no change in red blood cell deformability.

Adult↗