The power of slit-flow ektacytometry measurements for testing normal and heat treated red blood cells using various viscosity media in laboratory animals

Ferenc Kiss,Erika Sajtos,Timea Hever,Norbert Nemeth 한국유변학회 2010 Korea-Australia rheology journal Vol.22 No.1

Red blood cell (RBC) deformability values resulted from ektacytometry tests can be influenced by the viscosity of the medium in which the RBCs are suspended for measurement. To determine the power of measurements using various viscosity media in this study we used normal and heat treated RBCs from laboratory rats and beagle dogs. A RheoScan-D200 slit-flow ektacytometer was used to measure RBC deformability. Blood samples were taken from female Sprague-Dawley rats and inbred beagle dogs. Before and after heat treatment of RBC suspensions ektacytometry tests were performed using PVP solutions at viscosity of 15, 20and 30 mPa.s. Heat treatment caused impaired RBC deformability in both species and in every PVP solution. The difference between normal and heat treated RBCs was the highest in rats, while in dogs the magnitude of change was smaller, however being significant. Well comparable and stable results were found using 30 mPa.s media. The sensitivity of RBCs for heat treatment seems to be higher in rats. The suspending PVP medium at 30 mPa.s is recommended for testing RBC deformability by ektacytometry in laboratory rats and dogs, too, because this media resulted in the most stable data when comparing normal and rigid cells.

Testing red blood cell deformability of laboratory animals by slit-flow ektacytometry in various viscosity media: Inter-species and gender differences

Ferenc Kiss,Erika Sajtos,Lili Matyas,Zsuzsanna Magyar,Istvan Furka,Iren Miko,Norbert Nemeth 한국유변학회 2010 Korea-Australia rheology journal Vol.22 No.2

Viscosity of the suspending medium can be a determinant contributor to the effective measurements of red blood cell deformability using ektacytometry. Deformability of erythrocyte is known to show inter-species and gender differences, therefore the evaluation of the effects and the standardized usage of the suspending media are important in animal experiments. For evaluating the differences using various viscosity media, we aimed to test male and female Sprague-Dawley rats and beagle dogs. Blood samples were collected and red blood cell deformability was tested by a RheoScan-D200 slit-flow ektacytometer using parallel measurements in PVP solutions at viscosity of 15, 20 and 30mPa.s. The lowest elongation index values were measured in 15mPa.s solution in both species and genders. The inter-species differences were obvious: rats had higher elongation index values. Gender differences were found only in 20 and 30mPa.s samples: in rats males, while in dogs females had better red blood cell deformability. The standard usage of PVP solutions is essential for comparative studies, because the results obtained from different viscosity PVP solutions are not comparable to each other. In Sprague-Dawley rats and beagle dogs the relatively less viscous media (<20mPa.s) may result in less informative data.

Following-up changes in red blood cell deformability and membrane stability in the presence of PTFE graft implanted into the femoral artery in a canine model

Csaba Toth,Ferenc Kiss,Zoltan Klarik,Eszter Gergely,Eniko Toth,Katalin Peto,Erzsebet Vanyolos,Iren Miko,Norbert Nemeth 한국유변학회 2014 Korea-Australia rheology journal Vol.26 No.2

It is known that a moderate mechanical stress can even improve the red blood cells’ (RBC) micro-rheologicalcharacteristics, however, a more significant stress causes deterioration in the deformability. In thisstudy, we aimed to investigate the effect of the presence of artificial graft on the RBC deformability andmembrane stability in beagles. In the Control group only anesthesia was induced and in the postoperative(p.o.) period blood samplings were carried out. In the Grafted group under general anesthesia, the leftfemoral artery was isolated, from which a 3.5 cm segment was resected and a PTFE graft (O.D.: 3 mm)of equal in length was implanted into the gap. On the 1st, 3rd, 5th, 7th and 14th p.o. days blood was collectedthe cephalic veins and RBC deformability was determined ektacytometry (LoRRca MaxSis Osmoscan). Membrane stability test consisted of two deformability measurements before and after the cells werebeing exposed to mechanical stress (60 or 100 Pa for 300 seconds). Compared to the Control group andthe baseline values the red blood cell deformability showed significant deterioration on the 3rd, 5th andmainly on the 7th postoperative day after the graft implantation. The membrane stability of erythrocyterevealed marked inter-group difference on the 3rd, 5th and 7th day: in the Grafted group the deformabilitydecreased and during the membrane stability test smaller difference was observed between the statesbefore and after shearing. We concluded that the presence of a PTFE graft in the femoral artery maycause changes in RBC deformability in the first p.o. week. RBC membrane stability investigation showsa lower elongation index profile for the grafted group and a narrowed alteration in the deformabilitycurves due to mechanical stress.

Are there arterio-venous differences of blood micro-rheological variables in laboratory rats?

Timea Hever,Ferenc Kiss,Erika Sajtos,Lili Matyas,Norbert Nemeth 한국유변학회 2010 Korea-Australia rheology journal Vol.22 No.1

In animal experiments blood samples are often taken from various parts of the circulation. Although several variables including blood gas parameters are known to alter comparing arterial to venous system, arterio-venous (A-V) differences of blood micro-rheological variables (erythrocyte deformability and aggregation) tested by ektacytometry and aggregometry are not completely known in laboratory rats. In 12 outbred rats we investigated red blood cell deformability (RheoScan-D200 slit-flow ektacytometer), red blood cell aggregation (Myrenne MA-1 erythrocyte aggregometer), hematological variables (Sysmex F-800 microcell counter), blood pH and blood gases (ABL555 Radiometer Copenhagen) in blood samples taken parallel from the abdominal aorta and from the caudal caval vein. Blood pH did not differ, blood gas partial tensions showed physiological A-V differences, as it was expected. White blood cell count, red blood cell count and hematocrit were significantly higher in samples from the caval vein. Erythrocyte aggregation values (at 3 1/s shear rate) were significantly higher in samples taken from the abdominal aorta. Erythrocyte deformability (elongation index) did not show obvious A-V differences. Arterio-venous hemorheological differences -mostly of erythrocyte aggregation- can be found in rats, thus, the standardization of the studies and planning appropriate control measurements are necessary for safe evaluation of the obtained results.

Following-up changes in red blood cell deformability and membrane stability in the presence of PTFE graft implanted into the femoral artery in a canine model

Toth, Csaba,Kiss, Ferenc,Klarik, Zoltan,Gergely, Eszter,Toth, Eniko,Vanyolos, Katalin Peto Erzsebet,Miko, Iren,Nemeth, Norbert 한국유변학회 2014 Korea-Australia rheology journal Vol.26 No.2

It is known that a moderate mechanical stress can even improve the red blood cells' (RBC) micro-rheological characteristics, however, a more significant stress causes deterioration in the deformability. In this study, we aimed to investigate the effect of the presence of artificial graft on the RBC deformability and membrane stability in beagles. In the Control group only anesthesia was induced and in the postoperative (p.o.) period blood samplings were carried out. In the Grafted group under general anesthesia, the left femoral artery was isolated, from which a 3.5 cm segment was resected and a PTFE graft (O.D.: 3 mm) of equal in length was implanted into the gap. On the $1^{st}$, $3^{rd}$, $5^{th}$, $7^{th}$ and 14th p.o. days blood was collected the cephalic veins and RBC deformability was determined ektacytometry (LoRRca MaxSis Osmoscan). Membrane stability test consisted of two deformability measurements before and after the cells were being exposed to mechanical stress (60 or 100 Pa for 300 seconds). Compared to the Control group and the baseline values the red blood cell deformability showed significant deterioration on the $3^{rd}$, $5^{th}$ and mainly on the $7^{th}$ postoperative day after the graft implantation. The membrane stability of erythrocyte revealed marked inter-group difference on the $3^{rd}$, $5^{th}$ and $7^{th}$ day: in the Grafted group the deformability decreased and during the membrane stability test smaller difference was observed between the states before and after shearing. We concluded that the presence of a PTFE graft in the femoral artery may cause changes in RBC deformability in the first p.o. week. RBC membrane stability investigation shows a lower elongation index profile for the grafted group and a narrowed alteration in the deformability curves due to mechanical stress.

Investigation of the Effects of Oat and Barley Feeding on Performance and Some Lipid Parameters in Table Ducks

Orosz, Szilvia,Husveth, Ferenc,Vetesi, Margit,Kiss, Laszlo,Mezes, Miklos Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.7

The effects of barley and oat feeding in table duck were investigated. During a 49-day growing period a corn-based diet was supplemented by 45% barley and 45% oats (isonitrogenously and iso-energetically), respectively. Daily feed intake, FCR-, and weight gain were measured. Abdominal fat, liver, and gizzard weights were determined and dry matter, protein, fat content and fatty acid composition of femoro-tibial muscles and liver fat were measured on the $35^{th}$, $42^{nd}$ and $49^{th}$ days of age. Feeding 45% barley caused a decrease of growth rate ($p{\leq}0.05$) during the first 4 weeks, which was followed by a rapid, compensatory growth from the $6^{th}$ week of age ($p{\leq}0.05$). Both barley and oat supplementation increased protein ($p{\leq}0.05$), while decreasing fat ($p{\leq}0.05$) and dry matter ($p{\leq}0.05$) content of the liver. Feeding of 45% oats in the diet decreased the monounsaturated fatty acid ($p{\leq}0,05$) and increased the n-6 ($p{\leq}0,05$), n-3 ($p{\leq}0,05$) and total polyunsaturated ($p{\leq}0,05$) fatty acid content of the intramuscular fat owing to the high proportion of soluble non-starch polysaccharides (NSP) in the diet. This might be explained by the more pronounced decrease in digestibility of saturated than unsaturated fatty acids in birds fed a soluble NSP-enriched diet. This result might be caused by the "cage effect" of soluble NSP trapping the bile salts which are more important for the absorption of saturated than polyunsaturated fatty acids.

Storage of laboratory animal blood samples causes hemorheological alterations : Inter-species differences and the effects of duration and temperature

Norbert Nemeth,Oguz K. Baskurt,Herbert J. Meiselman,Ferenc Kiss,Mehmet Uyuklu,Timea Hever,Erika Sajtos,Peter Kenyeres,Kalman Toth,Istvan Furka,Iren Miko 한국유변학회 2009 Korea-Australia rheology journal Vol.21 No.2

Hemorheological results may be influenced by the time between blood sampling and measurement, and storage conditions (e.g., temperature, time) during sample delivery between laboratories may further affect the resulting data. This study examined possible hemorheological alterations subsequent to storage of rat and dog blood at room temperature (22℃) or with cooling (4~10℃) for 2, 4, 6, 24, 48 and 72 hours. Measured hemorheological parameters included hematological indices, RBC aggregation and RBC deformability. Our results indicate that marked changes of RBC deformability and of RBC aggregation in whole blood can occur during storage, especially for samples stored at room temperature. The patterns of deformability and aggregation changes at room temperature are complex and species specific, whereas those for storage at the lower temperature range are much less complicated. For room temperature storage, it thus seems logical to suggest measuring rat and dog cell deformability within 6 hours; aggregation should be measured immediately for rat blood or within 6 hours for dog blood. Storage at lower temperatures allows measuring EI up to 72 hours after sampling, while aggregation must be measured immediately, or if willing to accept a constant decrease, over 24~72 hours.

Storage of laboratory animal blood samples causes hemorheological alterations : Inter-species differences and the effects of duration and temperature

Nemeth, Norbert,Baskurt, Oguz K.,Meiselman, Herbert J.,Kiss, Ferenc,Uyuklu, Mehmet,Hever, Timea,Sajtos, Erika,Kenyeres, Peter,Toth, Kalman,Furka, Istvan,Miko, Iren The Korean Society of Rheology 2009 Korea-Australia rheology journal Vol.21 No.2

Hemorheological results may be influenced by the time between blood sampling and measurement, and storage conditions (e.g., temperature, time) during sample delivery between laboratories may further affect the resulting data. This study examined possible hemorheological alterations subsequent to storage of rat and dog blood at room temperature ($22^{\circ}C$) or with cooling ($4{\sim}10^{\circ}C$) for 2, 4, 6, 24, 48 and 72 hours. Measured hemorheological parameters included hematological indices, RBC aggregation and RBC deformability. Our results indicate that marked changes of RBC deformability and of RBC aggregation in whole blood can occur during storage, especially for samples stored at room temperature. The patterns of deformability and aggregation changes at room temperature are complex and species specific, whereas those for storage at the lower temperature range are much less complicated. For room temperature storage, it thus seems logical to suggest measuring rat and dog cell deformability within 6 hours; aggregation should be measured immediately for rat blood or within 6 hours for dog blood. Storage at lower temperatures allows measuring EI up to 72 hours after sampling, while aggregation must be measured immediately, or if willing to accept a constant decrease, over 24~72 hours.