Timea Hever

University of Debrecen, Debreczyn, Hajdú-Bihar, Hungary

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Publications (6)9.35 Total impact

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    ABSTRACT: It is known that hemorheological parameters show gender differences that might be altered by gonadectomy (GoE). Since micro-rheological parameters (erythrocyte deformability and aggregation) sensitively change during and after ischemia-reperfusion (I/R), the question arises whether the hemorheological effects of I/R may show gender differences and further changes might be expected when GoE and I/R are additive. Sprague-Dawley rats were divided into six groups: Control males and females, I/R males and females with 1-hour hind limb ischemia, GoE + I//R males and females when 3 months after bilateral gonadectomy the I/R was induced. Before and just after ischemia, and on the 1st-3rd-5th-7th postoperative days blood samples were taken (lateral tail vein, 0.3-0.5 mL) for analyzing hematological parameters, erythrocyte's deformability (slit-flow ektacytometer) and aggregation (light-transmission aggregometer). Leukocyte and platelet counts raised markedly in gonadectomized animals during the investigated days. Hemorheological changes of I/R showed gender differences: significant impairment of erythrocyte deformability was found on the 1st-3rd postoperative days, expressed mostly in females. In gonadectomized females the postischemic deformability values were impaired. Erythrocyte aggregation index significantly raised by the 1st postoperative day, dominantly in males. It is suggested that gonadectomy may act as an additional rheological 'risk factor' related to blood micro-rheological parameters in ischemia-reperfusion.
    Clinical hemorheology and microcirculation 01/2012; 50(3):197-211. DOI:10.3233/CH-2011-1427 · 2.24 Impact Factor
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    ABSTRACT: Clinical studied showed leukocyte antisedimentation rate (LAR) changes in various conditions that modulate the immune system. There is a lack of LAR data in animal experiments concerning splenic function after splenectomy or spleen preserving operations, thus we aimed to include LAR in our ongoing inbred canine study on following-up spleen salvaging surgical techniques. Blood samples of healthy beagle dogs served as normal control. The experimental groups were: "SH"-sham operated, "SE"-splenectomy, "R1/3" and "R2/3"-one-third/two-third of the spleen resected, "AU-5" and "AU-10"-autotransplantation with 5/10 spleen chips using Furka's techniques. On the 12th postoperative month Rabigen-Mono+Vanguard-Plus-5 vaccines were given to the animals, which provoked immune response. Blood samples were taken before and one week after the vaccination. LAR was calculated by Bogar's method. In normal control group LAR was 3.11, leukocyte count was 12.04 G/l. In the experimental groups LAR varied between 2.4-7.3 before vaccination. After vaccination LAR increased in all groups. Although "SE" group expressed the largest changes (LAR = 16.56; 135%), the leukocyte count increased only by 12%. In "AU" groups the increase was smaller, while "R" groups showed slight changes only. LAR can be applicable in animal experiments and may serve as a supplementary parameter in hemorheological investigations of hyposplenic-asplenic states.
    Clinical hemorheology and microcirculation 01/2010; 45(2-4):289-94. DOI:10.3233/CH-2010-1308 · 2.24 Impact Factor
  • Ferenc Kiss · Erika Sajtos · Timea Hever · Norbert Nemeth ·
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    ABSTRACT: 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, 20 and 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.
    Korea-Australia rheology journal 01/2010; 22(1):81-86. · 0.88 Impact Factor
  • Timea Hever · Ferenc Kiss · Erika Sajtos · Lili Matyas · Norbert Nemeth ·
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    ABSTRACT: 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, arte-rio-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 stan-dardization of the studies and planning appropriate control measurements are necessary for safe evaluation of the obtained results.
    Korea-Australia rheology journal 01/2010; 22(1):59-64. · 0.88 Impact Factor
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    ABSTRACT: Blood samples used in hemorheological studies may be stored for a period of time, the effects of storage have yet to be fully explored. This study evaluated the effects of storage temperature (i.e., 4 degrees C or 25 degrees C) and duration on RBC deformability and aggregation for blood from healthy controls and from septic patients. Our results indicate that for normal blood, RBC deformability over 0.3-50 Pa is stable up to six hours regardless of storage temperature; at eight hours there were no significant differences in EI but SS1/2 calculated via a Lineweaver-Burk method indicated impaired deformability. Storage temperature affected the stable period for RBC aggregation: the safe time was shorter at 25 degrees C whereas at 4 degrees C aggregation was stable up to 12 hours. Interestingly, blood samples from septic patients were less affected by storage. Blood can thus be stored at 25 degrees C for up to six hours for deformability studies, but should be limited to four hours for RBC aggregation; storage at 4 degrees C may prolong the storage period up to 12 hours for aggregation but not deformability measurements. Therefore, the time period between sampling and measurement should be as short as possible and reported together with results.
    Clinical hemorheology and microcirculation 02/2009; 41(4):269-78. DOI:10.3233/CH-2009-1178 · 2.24 Impact Factor
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    Korea-Australia rheology journal 01/2009; 21(2):127-133. · 0.88 Impact Factor

Publication Stats

42 Citations
9.35 Total Impact Points


  • 2009-2012
    • University of Debrecen
      • Institute of Surgery
      Debreczyn, Hajdú-Bihar, Hungary