Biomedical subjects

Mabel D'Arrigo

Publications and source records attributed to Mabel D'Arrigo.

4 recordsLinked to original sources

PubMed2006

Laser diffractometry technique: clinical applications to vascular pathologies.

Hypertension (HTA) and dyslipidemia (DLP) represent major risk factors for cardiovascular and cerebral-vascular ischemic disease. The mechanisms through which they can induce vascular damage are both metabolic and mechanical. Hemorheological alterations in HTA are result of changes affecting both red cell intrinsic structure and their interactions with the plasmatic components. Several hemorheological determinants (biochemical, ionic, metabolic and rheologic) could influence and produce an impaired erythrocyte deformability determining an increased flow resistance in the microcirculation. The "Erythrodeformeter" allows obtaining the stationary and dynamical linear parameters of erythrocyte membrane by laser diffractometry. Stationary and oscillatory shear-induced elongation of cells leads to an elliptical diffraction pattern, its geometric characteristics being directly related to those of deformed RBC. Erythrocyte stationary parameters (Deformability Index, surface viscosity and elastic modulus) were obtained in stationary regime. Complex viscoelastic parameters (dynamic elasticity, dynamic loss, viscous and elastic components of the complex viscosity) were obtained when operating in oscillating mode. The diffractometric method is sensitive to detect pathological or induced alterations on RBC membrane, which can affect blood flow in vivo. The rheological parameters obtained give important information about the erythrocyte membrane and allow to detect and characterize erythrocyte alterations in vascular pathologies.

Dyslipidemias↗

PubMed2005

[Hemorheological alterations in hypertensive patients].

The aim of this study was to investigate the blood viscosity profile and to evaluate the influence of plasmatic (fibrinogen) and cellular (erythrocyte aggregation) factors in a group of hypertensive patients, compared with a normotensive group. We worked with anticoagulated blood of both non diabetic hypertensive patients (n=31), and healthy individuals (n=40). The plasmatic viscosity and whole blood determination were obtained with a cone-plate viscometer. Erythrocyte aggregation was studied by microscopical observation and quantified by an Aggregate Shape Parameter (ASP), defined as the relation projected area/perimeter. Fibrinogen was determined by the Clauss method with a coagulometer. A comparison between these groups led us to assert that whole blood viscosity was significantly higher in hypertensive patients than in the controls at all shear rates. Plasma viscosity values only showed significant differences between both groups at low shear rate (1.15 a 11.56 seg(-1)). The hypertensive patients showed irregular and amorphous aggregates so that ASP appeared significantly higher (p< 0.001) in patients with hypertension (0.69 +/- 0.11) than in healthy subjects (0.25 +/- 0.12). Fibrinogen appeared slightly higher (p<0.01) in the hypertensive group than in the normal group. Several hemorheological parameters play important roles in the pathogenesis of hypertension. Among these factors, several hemorheological parameters could be altered in hypertension (hematocrit, plasma fibrinogen level, erythrocyte deformability and aggregability, plasma and whole blood viscosity). An increased RBC aggregation has been identified as an important factor responsible for disturbing blood rheological behavior in the microcirculation. The present study demonstrates an abnormal erythrocyte aggregation, which was detected by increased ASP values that could be responsible for vascular complications in hypertension.

Adult↗

PubMed2004

A dynamic and stationary rheological study of erythrocytes incubated in a glucose medium.

A higher than normal glucose concentration in a suspending medium may produce non-enzymatic glycosylation of erythrocyte proteins. This process can modify the viscoelastic properties of erythrocytes. In this paper, we studied the possible relationship between glucose concentration in a suspending medium and erythrocyte rheological parameters. Human venous blood was obtained from the antecubital veins of 10 healthy volunteers. Blood samples were anticoagulated with EDTA and centrifuged. Red blood cells (RBCs) were washed and subsequently divided in aliquots, which were incubated in vitro with glucose solutions of different concentrations. Dynamic and stationary viscoelastic parameters of RBCs were determined by laser diffractometry in an Erythrodeformeter. Aggregate shape parameter (ASP) of the RBCs was determined by digital image processing. Significant changes were observed both in ASP and in rheological parameters when the glucose concentration in the medium was increased, demonstrating that a glucose concentration as low as 1% induces alterations in the mechanical properties of RBCs.

Culture Media↗

PubMed2002

Comparative analysis of aggregate shapes by digitized microscopic images. Application to hypertension.

The main objective of the present work was to study modifications in RBC aggregate morphology by analyzing digitized microscopic images and compare them between healthy subjects and patients suffering from essential hypertension. Blood samples were obtained from normal subjects (n=30) and patients suffering from essential hypertension (n=20). RBC aggregate morphology was quantified using direct microscopic observation and numerical analysis of images. ASP (Aggregation Shape Parameter) defined as the ratio of the area of the projected image to its square perimeter was calculated. Other rheological parameters have been determined in order to establish the hemorheological profile of the studied hypertension states. ASP appears significantly higher (p<0.001) in patients suffering essential hypertension (0.69+/-0.11) than in normal control subjects (0.25+/-0.12). RBC aggregation is known to be responsible for the high increase in apparent blood viscosity at low shear rates. By compare ASP values with whole blood viscosity at low rate (2.30 s(-1)) a high correlation was formed between both parameters (Spearman coefficient was 0.8835 and p<0.001). The applied method is simple, direct and quantitative and provides a useful tool for measuring deviations of RBC aggregate morphology.

Adult↗