Clinical Hemorheology and Microcirculation

Studies of RBC morphological alterations, despite their potential clinical and experimental application, are compromised due to lack of simple and rapid techniques. As a complementary approach toward quantitative microscopy, we have reconstituted morphological information from light scattering data obtained from flow cytometer. Normal and poikilocytic agent treated samples were analyzed by microscopy and respective morphological index (MI) was calculated from the morphology based scores assigned to RBC. The samples were simultaneously analyzed by flowcytometer and the scatter data were obtained. Accordingly, the best correlated parameters of both forward scatter and side scatter were chosen to formulate a suitable regression model with MI as response. Flow cytometry data was also verified with another instrument (BD FACS Verse) and the equation obtained was validated with separate set of samples. The multivariate regression analysis yields a quadratic model with MI as response (R² = 0.96, p <  0.001). The flow cytometric data from both instruments were in good agreement (Intra class correlation ∼0.9, p <  0.001). The model was found to simulate the sample MI with high accuracy (R² = 0.97, p <  0.001). This proposed method was verified to be simple, rapid, quantitative and cost effective for the measurement of morphological alteration of RBC.

BACKGROUND: The presence of silent cerebral infarction (SCI) increases the risk of transient ischemia attack, symptomatic stroke, cardiovascular disease and dementia. Increased viscosity is associated with aging, obesity, carotid intima-media thickness, metabolic syndrome, hypertension, diabetes, ischemic heart disease, and stroke.

AIMS: The purpose of the study was to assess the hemorheological parameters levels in SCI patients.

METHODS: A cross-sectional study was conducted to evaluate the association between hemorheological parameters and SCI in 1487 subjects (868 men and 619 women) undergoing medical check-up.

RESULTS: The participants with SCI had higher whole blood viscosity (WBV) levels at low shear rate than those without SCI (10.34 ± 1.77 mPa.s vs. 8.98 ± 0.88 mPa.s; P <  0.001). Moreover, the subjects with a high WBV had a higher prevalence of SCI. Logistic regression analysis revealed that a significant association of WBV levels with the risk of SCI after adjustment for confounding factors (OR: 2.025; 95% CI: 1.750–2.343; P <  0.001).

CONCLUSIONS: Whole blood viscosity at low shear rate is a novel indicator for SCI regardless of classical cardiovascular risk factors. Early measurement of whole blood viscosity may be helpful to assess the risk of stroke.

Despite microcirculation’s fundamental role, assessments of its function are limited. We explored the applicability of Computer Assisted Video Microscope (CAVM), Laser Doppler Perfusion Measurements (LDPM) and Diffuse Reflectance Spectroscopy (DRS) to study skin microvascular morphology, perfusion and oxygen saturation in twenty-five healthy newborns day 1–3 of life.

Results: Day 1–3 (mean (SD)): Microvascular density (CAVM; number of microvessels crossing a grid of lines/mm line, c/mm): Chest: 11.3 (1.5), 11.0 (1.7), 10.7 (1.6). Hand: 13.2 (2.0), 13.2 (1.9), 12.4 (1.6). Capillary density was significantly higher in the hand than in the chest each day (p <  0.001). Perfusion (LDPM; arbitrary units): Chest: 109.1 (26.0), 101.4 (24.6), 100.8 (25.3). Hand: 58.9 (17.5), 54.3 (15.8), 46.9 (14.8). Perfusion was significantly higher in the chest than in the hand each day (p <  0.01). Microvascular oxygen saturation (DRS; %): Chest: 88.1 (5.2), 87.8 (10.0), 86.7 (9.0). Hand: 79.9 (15.2), 82.7 (11.8), 82.2 (12.1) (p <  0.05). Capillary flow velocities (CAVM) were similar in the chest and hand: 60–70% capillaries had “continuous high flow” and 30–40% “continuous low flow”.

Multimodal skin microvascular assessments with CAVM, LDPM and DRS are feasible with reproducible data in newborns. The hand has lower perfusion, higher capillary density and higher oxygen extraction than the chest.

INTRODUCTION: Obesity is associated with impaired microvascular endothelial function. We aimed to determine the effects of orlistat and sibutramine treatment on microvascular endothelial function, anthropometric and lipid profile, blood pressure (BP), and heart rate (HR). METHODS: 76 subjects were recruited and randomized to receive orlistat 120 mg three times daily or sibutramine 10 mg daily for 9 months. Baseline weight, BMI, BP, HR and lipid profile were taken. Microvascular endothelial function was assessed using laser Doppler fluximetry and iontophoresis process. Maximum change (max), percent change (% change) and peak flux (peak) in perfusion to acetylcholine (ACh) and sodium nitroprusside (SNP) iontophoresis were used to quantify endothelium dependent and independent vasodilatations. RESULTS: 24 subjects in both groups completed the trial. After treatment, weight and BMI were decreased for both groups. ACh_max, ACh % change and ACh peak were increased in orlistat-treated group but no difference was observed for sibutramine-treated group. BP and total cholesterol (TC) were reduced for orlistat-treated group. HR was reduced for orlistat-treated group but was increased in sibutramine-treated group. CONCLUSION: 9 months treatment with orlistat significantly improved microvascular endothelial function. This was associated with reductions in weight, BMI, BP, HR, TC and low density lipoprotein cholesterol. No effect was seen in microvascular endothelial function with sibutramine.

BACKGROUND: The goal of this study was to determine whether the focused delivery of APC by rinsing of free adipocutaneous groin flaps shows protective effects on flap survival following a fatal secondary venous stasis in a rat model.

METHODS: 36 Sprague Dawley rats were randomized to three groups and free microvascular groin flaps were transplanted to the neck in each animal. 20 hours postoperatively the flap pedicle was re-explored and the distal stump of the flap artery was catheterised. Animals in group I (n = 12) remained untreated, whereas animals of group II were treated with 1 ml of Ringer’s solution. Those in group III received 1 ml of APC (2 mg/kg). Afterwards the flap vein was clamped for 35 minutes. The skin of the flaps and the native contralateral groin was examined by intravital video microscopy using FITC-Dextran and CFDA-SE-labelled thrombocytes.

RESULTS: APC-pretreatment significantly increased the functional capillary density (FCD) of the flaps. Flap viability was 8% in group I (n = 1/12), 9% in group II (n = 1/11) and 60% in group III (n = 6/10), respectively. No partial flap loss was detected.

CONCLUSIONS: The focused delivery of APC resulted in significantly improved flap salvage.

We have previously showed that morphological alterations in Red Blood Cells (RBCs) are correlated to an impaired eNOS enzymatic activity and a concomitant reduced NO derived metabolites formation. Here we extend our previous observations, reporting that RBC morphology is regulated by a series of specific cell signaling events linked to Protein Kinase C (PKC)-mediated activation of caspase 3. Pretreatment of RBCs with the PKC inhibitor chelerythrine, prior to the addition of phorbol-12-myristate-13-acetate (PMA), an activator of PKC, blocks the appearance of the morphology alterations and the sustained decrease in nitrates and nitrites levels induced by PMA. Inhibition of PKC also completely inhibits PMA mediated caspase-3 activation. On the other hand, caspase 3 inhibition, lessens the PMA induced-effects on the appearance of RBC morphology alterations, although it enhances PMA-mediated effects on nitric oxide (NO) derived metabolites levels. These data demonstrate that PKC-mediated activation of caspase 3 is an integral and essential part of signaling pathway in RBCs, that may be a regulatory factor of RBC mechanical properties, through regulation of NO metabolism.

Humans are exposed to heavy metals such as arsenic (As), through contaminated food and drinking water. The effect of As on RBC membrane is one of the most important biological effects. In a previous work, we have studied the As^V in vitro effect on erythrocytes biophysical properties discovering alterations regarding aggregability deformability, cell morphology, membrane fluidity and osmotic response. We have also observed that the presence of the metal produces an oxidative stress in RBCs that might be the origin of rheological impairment. In the present work we analyzed RBCs rheological properties associated with membrane fluidity and lipid peroxidation in presence of As and quercetin (Qc). From our results we can conclude that RBCs treatment with Qc is efficient to prevent the impairment of the mechanical properties of the cell membrane produced by the As, through oxygen reactive agents in the membrane structure, mainly on the lipids. This protective effect is observed in the preservation of the erythrocytes rheological properties and consequently in the maintenance of an appropriate blood flow, specially in the small vessels in the peripheral circulation.

Hypertension, decreased glucose tolerance, adverse lipid profiles and low physical activity levels are associated with increased type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD) risk. High intensity interval training (HIIT), a low volume, reduced time, high intensity programme, may be a useful alternative to current government guidelines which specify a minimum of 150 minutes of physical activity per week. We describe a personalised programme of high intensity exercise which provides significant improvements in CVD risk markers. Healthy volunteers undertook 6 weeks of HIIT. T2DM and CVD risk predictors including glucose tolerance, VO_2max, blood pressure (BP), and lipids were measured before and after HIIT. HIIT training was associated with beneficial changes in a range of predictors of blood flow and cardiovascular risk. There was a heterogeneous response to HIIT, with some subjects responding with favourable changes and others being non-responders to HIIT. In responders, HIIT was associated with a statistically significant (p = 0.023) increase in VO_2max, from 45.4 (38.4,52.5) to 56.9 (51.2,65.7) (median (interquartile range)(ml/min/kg)). In responders HIIT resulted in a decrease in systolic BP from 127 (126,129) to 116 (106,122) (mmHg) with p = 0.026 and a decrease is diastolic blood pressure from 72 (69,74) to 57 (56,66) with p = 0.026. There was also some evidence of a beneficial change in blood lipid and glucose concentrations with HIIT. In conclusion, personalised HIIT has potential as an intervention to improve blood flow and cardiovascular health.

Red blood cell distribution width (RDW) is a routine red blood cell count parameter which has been shown to be associated with inflammatory parameters. Recently, some authors proposed that RDW seems to be a marker of an adverse lipidic profile. In order to clarify whether RDW is related to inflammation, plasma lipids, or both, we determined anthropometric, hematimetric, inflammatory and lipidic parameters in 1111 healthy subjects. RDW correlated directly with age, body mass index (BMI), inflammatory parameters (plasma viscosity, erythrocyte sedimentation rate (ESR), fibrinogen, leukocyte and neutrophil count), and inversely with iron and hematimetric parameters (P <  0.05). When subjects were divided according to gender, RDW correlated inversely with triglycerides only in women (P <  0.05). When subjects were classified into RDW-quartiles, increased RDW values were accompanied by decreased serum iron levels and hematimetric indices (P <  0.01), whereas age and inflammatory markers increased according to RDW-quartiles (P <  0.001 and P <  0.05, respectively). However, plasma lipids did not change with increasing RDW-quartiles (P >  0.05). In the linear regression analysis, age, hemoglobin, MCV (beta coefficient: 0.202, −0.234, −0.316, P <  0.001) and fibrinogen (beta coefficient: 0.059, P = 0.048) were the only independent predictors of RDW. The present study indicates that RDW is associated with inflammatory markers and hematimetric indices, but not with plasma lipid levels in a healthy population.