Immune and hemorheological changes in Chronic Fatigue Syndrome

BACKGROUND: Chronic Fatigue Syndrome (CFS) is a multifactorial disorder that affects various physiological systems including immune and neurological systems. The immune system has been substantially examined in CFS with equivocal results, however, little is known about the role of neutrophils and natural killer (NK) phenotypes in the pathomechanism of this disorder. Additionally the role of erythrocyte rheological characteristics in CFS has not been fully expounded. The objective of this present study was to determine deficiencies in lymphocyte function and erythrocyte rheology in CFS patients. METHODS: Flow cytometric measurements were performed for neutrophil function, lymphocyte numbers, NK phenotypes (CD56(dim)CD16(+ )and CD56(bright)CD16(-)) and NK cytotoxic activity. Erythrocyte aggregation, deformability and fibrinogen levels were also assessed. RESULTS: CFS patients (n = 10) had significant decreases in neutrophil respiratory burst, NK cytotoxic activity and CD56(bright)CD16(- )NK phenotypes in comparison to healthy controls (n = 10). However, hemorheological characteristic, aggregation, deformability, fibrinogen, lymphocyte numbers and CD56(dim)CD16(+ )NK cells were similar between the two groups. CONCLUSION: These results indicate immune dysfunction as potential contributors to the mechanism of CFS, as indicated by decreases in neutrophil respiratory burst, NK cell activity and NK phenotypes. Thus, immune cell function and phenotypes may be important diagnostic markers for CFS. The absence of rheological changes may indicate no abnormalities in erythrocytes of CFS patients

Red blood cell aggregation parameters measured by capillary tube aggregometer using venous and capillary blood samples

The extent of red blood cell (RBC) aggregation has widely been accepted as a reliable indicator of inflammatory processes. The ability to measure RBC aggregation indexes in capillary blood samples may simplify the application of the test and may bring advantages in its clinical usage as well as application in field studies. This study compared RBC aggregation indexes measured in venous and capillary blood samples using a newly developed capillary tube aggregometer. Although strong correlations between aggregation indexes measured in capillary and venous samples were detected, the indexes measured in venous samples were higher compared to capillary samples, thus indicating a bias. The possible reason for this bias is proposed to be related to the difference in oxygen saturation of venous and capillary samples and therefore altered the light absorption spectrums. Our results indicate that capillary blood samples can be used to estimate RBC aggregation in venous blood samples, however the bias should be taken into account.No Full Tex

Red blood cell aggregation parameters measured by capillary tube aggregometer using venous and capillary blood samples

The extent of red blood cell (RBC) aggregation has widely been accepted as a reliable indicator of inflammatory processes. The ability to measure RBC aggregation indexes in capillary blood samples may simplify the application of the test and may bring advantages in its clinical usage as well as application in field studies. This study compared RBC aggregation indexes measured in venous and capillary blood samples using a newly developed capillary tube aggregometer. Although strong correlations between aggregation indexes measured in capillary and venous samples were detected, the indexes measured in venous samples were higher compared to capillary samples, thus indicating a bias. The possible reason for this bias is proposed to be related to the difference in oxygen saturation of venous and capillary samples and therefore altered the light absorption spectrums. Our results indicate that capillary blood samples can be used to estimate RBC aggregation in venous blood samples, however the bias should be taken into account.No Full Tex

Heart rate variability is related to impaired haemorheology in older women with type 2 diabetes

Impaired heart rate variability (HRV) and haemorheology are independently associated with cardiovascular disease and diabetic complications. The aim of the present study was to investigate the relationships between parameters of HRV, and red blood cell (RBC) aggregation and deformability, in older women with type 2 diabetes. Twenty women (age 69±2 yr) with uncomplicated type 2 diabetes and twenty controls (age 69±3 yr) participated in the study. Beat-to-beat cardiac (RR) intervals over 5 min were analysed for HRV parameters in the time and frequency domains. Blood was sampled for RBC deformability, as well as RBC aggregation in two suspending mediums: haematocrit adjusted plasma and 3% dextran 70. RBC aggregation was increased and HRV was impaired for those with type 2 diabetes when compared with control. RBC aggregation was negatively related to low frequency power of HRV, and was positively related to high frequency power of HRV, for subjects with type 2 diabetes. RBC deformability was positively related to HRV only for those with type 2 diabetes. Impaired haemorheology is associated with reduced HRV in older women with type 2 diabetes, suggesting changes in the microcirculation may result in impaired modulation of cardiac cycles

Heart rate variability is related to impaired haemorheology in older women with type 2 diabetes

Impaired heart rate variability (HRV)and haemorheology are independently associated with cardiovascular disease and diabetic complications. The aim of the present study was to investigate the relationships between parameters of HRV,and red blood cell (RBC) aggregation and deformability, in older women with type 2 diabetes. Twenty women (age 69 ᠲ yr) with uncomplicated type 2 diabetes and twenty controls (age 69 ᠳ yr) participated in the study. Beat-to-beat cardiac (RR) intervals over 5 min were analysed for HRV parameters in the time and frequency domains. Blood was sampled for RBC deformability, as well as RBC aggregation in two suspending mediums: haematocrit adjusted plasma and 3% dextran 70. RBC aggregation was increased and HRV was impaired for those with type 2 diabetes when compared with control. RBC aggregation was negatively related to low frequency power of HRV, and was positively related to high frequency power of HRV, for subjects with type 2 diabetes. RBC deformability was positively related to HRV only for those with type 2 diabetes. Impaired haemorheology is associated with reduced HRV in older women with type 2 diabetes, suggesting changes in the microcirculation may result in impaired modulation of cardiac cycles.No Full Tex

Immune and hemorheological changes in Chronic Fatigue Syndrome

Abstract Background Chronic Fatigue Syndrome (CFS) is a multifactorial disorder that affects various physiological systems including immune and neurological systems. The immune system has been substantially examined in CFS with equivocal results, however, little is known about the role of neutrophils and natural killer (NK) phenotypes in the pathomechanism of this disorder. Additionally the role of erythrocyte rheological characteristics in CFS has not been fully expounded. The objective of this present study was to determine deficiencies in lymphocyte function and erythrocyte rheology in CFS patients. Methods Flow cytometric measurements were performed for neutrophil function, lymphocyte numbers, NK phenotypes (CD56dimCD16+ and CD56brightCD16-) and NK cytotoxic activity. Erythrocyte aggregation, deformability and fibrinogen levels were also assessed. Results CFS patients (n = 10) had significant decreases in neutrophil respiratory burst, NK cytotoxic activity and CD56brightCD16- NK phenotypes in comparison to healthy controls (n = 10). However, hemorheological characteristic, aggregation, deformability, fibrinogen, lymphocyte numbers and CD56dimCD16+ NK cells were similar between the two groups. Conclusion These results indicate immune dysfunction as potential contributors to the mechanism of CFS, as indicated by decreases in neutrophil respiratory burst, NK cell activity and NK phenotypes. Thus, immune cell function and phenotypes may be important diagnostic markers for CFS. The absence of rheological changes may indicate no abnormalities in erythrocytes of CFS patients.</p

Haemorheology of the eastern grey kangaroo and the Tasmanian devil

The blood of two Australian marsupials, the eastern grey kangaroo (Macropus giganteus) and the Tasmanian devil (Sarcophilus harrisii), has been reported to have greater oxygen-carrying capacity (i.e. haemoglobin content) when compared with that of placental mammals.Weinvestigated whether alterations of blood rheological properties are associated with the increased oxygen-carrying capacity of these marsupials. Eastern grey kangaroos (n = 6) and Tasmanian devils (n=4) were anaesthetised for blood sampling; human blood (n = 6) was also sampled for comparison. Laboratory measurements included blood and plasma viscosity, red blood cell (RBC) deformability, RBC aggregation and the intrinsic tendency of RBC to aggregate, RBC surface charge and haematological parameters. Scanning electron micrographs of RBC from each species provided morphological information. High-shear blood viscosity at native haematocrit was highest for the Tasmanian devil. When haematocrit was adjusted to 0.4 L L-1, lower-shear blood viscosity was highest for the eastern grey kangaroo. RBC deformability was greatly reduced for the Tasmanian devil. Eastern grey kangaroo blood had the highest RBC aggregation, whereas Tasmanian devil RBC did not aggregate. The surface charge of RBC for marsupials was ~15% lower than that of humans. The dependence of oxygen-delivery effectiveness on haemoglobin concentration (i.e. oxygen content) and blood viscosity was quantitated by calculating the haematocrit to blood viscosity ratio and was 15-25% lower for marsupials compared with humans. Our results suggest that environmental pressures since the marsupial-monotreme divergence have influenced the development of vastly different strategies to maintain a match between oxygen demand and delivery.Griffith Health FacultyNo Full Tex

Assessment of oxidant susceptibility of red blood cells in various species based on cell deformability

The present study was designed to investigate the oxidant susceptibility of red blood cells (RBC) from four species (echidna, human, koala, Tasmanian devil) based on changes in cellular deformability. These species were specifically chosen based on differences in lifestyle and/or biology associated with varied levels of oxidative stress. The major focus was the influence of superoxide radicals generated within the cell (phenazine methosulfate, PMS, 50 卩 or in the extracellular medium (xanthine oxidase-hypoxanthine, XO-HX, 0.1 U/ml XO) on RBC deformability at various shear stresses (SS). RBC deformability was assessed by laser-diffraction analysis using a "slit-flow ektacytometer". Both superoxide-generating treatments resulted in significant increases of methemoglobin for all species (p<0.01), with Tasmanian devil RBC demonstrating the most sensitivity to either treatment. PMS caused impaired RBC deformability for all species, but vast interspecies variations were observed: human and koala cells exhibited a similar sigmoid-like response to SS, short-beaked echidna values were markedly lower and only increased slightly with SS, while Tasmanian devil RBC were extremely rigid. The effect of XO-HX on RBC deformability was less when compared with PMS (i.e., smaller increase in rigidity) with the exception of Tasmanian devil RBC which exhibited essentially no deformation even at the highest SS; Tasmanian devil RBC response to XO-HX was thus comparable to that observed with PMS. Our findings indicate that ektacytometry can be used to determine the oxidant susceptibility of RBC from different species which varies significantly among mammals representing diverse lifestyles and evolutionary histories. These differences in susceptibility are consistent with species-specific discrepancies between observed and allometrically-predicted life spans and are compatible with the oxidant theory of aging.No Full Tex