Effects of H2S-donor ascorbic acid derivative and ischemia/reperfusion-induced injury in isolated rat hearts.

Hydrogen sulfide (H2S), a gasotransmitter, plays a crucial role in vasorelaxation, anti-inflammatory processes and mitigating myocardial ischemia/reperfusion-induced injury by regulating various signaling processes. We designed a water soluble H2S-releasing ascorbic acid derivative, BM-164, to combine the beneficial cardiovascular and anti-inflammatory effects of H2S with the excellent water solubility and antioxidant properties of ascorbic acid. DPPH antioxidant assay revealed that the antioxidant activity of BM-164 in the presence of a myocardial tissue homogenate (extract) increased continuously over the 120 min test interval due to the continuous release of H2S from BM-164. The cytotoxicity of BM-164 was tested by MTT assay on H9c2 cells, which resulted in no cytotoxic effect at concentrations of 10 to 30 µM. The possible beneficial effects of BM-164 (30 µM) was examined in isolated 'Langendorff' rat hearts. The incidence of ventricular fibrillation (VF) was significantly reduced from its control value of 79 % to 31 % in the BM-164 treated group, and the infarct size was also diminished from the control value of 28 % to 14 % in the BM-164 treated group. However, coronary flow (CF) and heart rate (HR) values in the BM-164 treated group did not show significantly different levels in comparison with the drug-free control, although a non-significant recovery in both CF and HR was observed at each time point. We attempted to reveal the mechanism of action of BM-164, focusing on the processes of autophagy and apoptosis. The expression of key autophagic and apoptotic markers in isolated rat hearts were detected by Western blot analysis. All the examined autophagy-related proteins showed increased expression levels in the BM-164 treated group in comparison to the drug-free control and/or ascorbic acid treated groups, while the changes in the expression of apoptotic markers were not obvious. In conclusion, the designed water soluble H2S releasing ascorbic acid derivative, BM-164, showed better cardiac protection against ischemia/reperfusion-induced injury compared to the untreated and ascorbic acid treated hearts, respectively.

Evaluation of the Diagnosis and Antibiotic Prescription Pattern in Patients Hospitalized with Urinary Tract Infections: Single-Center Study from a University-Affiliated Hospital.

UTIs (urinary tract infections) are common bacterial infections with a non-negligible hospitalization rate. The diagnosis of UTIs remains a challenge for prescribers and a common source of misdiagnosis. This retrospective observational study aimed to evaluate whether recorded diagnosis by clinicians and empirical antibiotic therapy met the EAU (European Association of Urology) guideline in patients hospitalized with UTI. The study was conducted at an internal medicine unit of a tertiary care medical center in Hungary. The diagnosis was assessed based on clinical presentation, physical examination, and laboratory (including microbiological) results, considering all the potential risk factors. Diagnosis was considered misdiagnosis when not confirmed by clinical presentation or clinical signs and symptoms. Evaluation of empirical antibiotic therapy was performed only for confirmed UTIs. Empirical treatment was considered guideline-adherent when complying with the relevant recommendations. Out of 185 patients, 41.6% failed to meet EAU-based UTI diagnosis criteria, of which 27.6% were misdiagnosed and 14.1% were ABU (asymptomatic bacteriuria). The diagnosis of urosepsis recorded at admission (9.7%, 18/185) was not confirmed either by clinical or microbiological tests in five (5/18) cases. The initial empirical therapies for UTI showed a relatively low rate (45.4%) of guideline adherence regarding agent selection. The most common guideline-non-adherent therapies were combinations with metronidazole (16.7%). Dosage appropriateness assessments showed a guideline adherence rate of 36.1%, and underdosing due to high body weight was common (9.3%). Overall (agent, route of administration, dose, duration) guideline adherence was found to be substantially low (10.2%). We found a relatively high rate of misdiagnosed UTIs. Written protocols on the ward may be crucial in reducing misdiagnosis and in optimizing antibiotic use.

Changes of Hematological and Hemorheological Parameters in Rabbits with Hypercholesterolemia.

Hypercholesterolemia plays an important role in the development of atherosclerosis, leading to endothelial dysfunction, ischemic events, and increased mortality. Numerous studies suggest the pivotal role of rheological factors in the pathology of atherosclerosis. To get a more detailed hematological and hemorheological profile in hypercholesterolemia, we carried out an experiment on rabbits. Animals were divided into two groups: the control group (Control) was kept on normal rabbit chow, the high-cholesterol diet group (HC) was fed with special increased cholesterol-containing food. Hematological parameters (Sysmex K-4500 automate), whole blood and plasma viscosity (Hevimet-40 capillary viscometer), red blood cell (RBC) aggregation (Myrenne MA-1 aggregometer), deformability and mechanical stability (LoRRca MaxSis Osmoscan ektacytometer) were tested. The white blood cell and platelet count, mean corpuscular volume, and mean corpuscular hemoglobin were significantly higher in the HC group, while the RBC count, hemoglobin, and hematocrit values were lower than the Control data. Viscosity values corrected to 40% hematocrit were higher in the HC group. The RBC aggregation significantly increased in the HC vs. the Control. The HC group showed significantly worse results both in RBCs' deformability and membrane stability. In conclusion, the atherogenic diet worsens the hematological and macro- and micro-rheological parameters, affecting blood flow properties and microcirculation.

In vitro effects of temperature on red blood cell deformability and membrane stability in human and various vertebrate species.

BACKGROUND: The effects of temperature on micro-rheological variables have not been completely revealed yet. OBJECTIVE: To investigate micro-rheological effects of heat treatment in human, rat, dog, and porcine blood samples. METHODS: Red blood cell (RBC) - buffer suspensions were prepared and immersed in a 37, 40, and 43°C heat-controlled water bath for 10 minutes. Deformability, as well as mechanical stability of RBCs were measured in ektacytometer. These tests were also examined in whole blood samples at various temperatures, gradually between 37 and 45°C in the ektacytometer. RESULTS: RBC deformability significantly worsened in the samples treated at 40 and 43°C, more expressed in human, porcine, rat, and in smaller degree in canine samples. The way of heating (incubation vs. ektacytometer temperation) and the composition of the sample (RBC-PBS suspension or whole blood) resulted in the different magnitude of RBC deformability deterioration. Heating affected RBC membrane (mechanical) stability, showing controversial alterations. CONCLUSION: Significant changes occur in RBC deformability by increasing temperature, showing inter-species differences. The magnitude of alterations is depending on the way of heating and the composition of the sample. The results may contribute to better understanding the micro-rheological deterioration in hyperthermia or fever.

Examination of the relation between red blood cell aggregation and hematocrit in human and various experimental animals.

BACKGROUND: Red blood cell (RBC) aggregation plays an important role in the physiological processes of the microcirculation. The complete mechanism of aggregation is still unclear, and it is influenced by several cellular and plasmatic factors. One of these factors is the hematocrit (Hct). OBJECTIVE: We hypothesized that the relation of RBC aggregation and Hct differs between species. METHODS: From anticoagulated blood samples of healthy volunteers, rats, dogs, and pigs, 20, 40, and 60 %Hct RBC, autologous plasma suspensions were prepared. Hematological parameters and RBC aggregation was determined by light-transmission and light-reflection method. RESULTS: Suspensions at 20%and 60%Hct expressed lower RBC aggregation than of 40%Hct suspensions, showing inter-species differences. By curve fitting the Hct at the highest aggregation value differed in species (human: 45.25%- M 5 s, 40.86%- amp; rat: 44.44 %- M1 10 s, 39.37%- amp; dog: 42.48%- M 5 s, 44.29%- amp; pig: 47.63%- M 5 s, 52.8%- amp). CONCLUSION: RBC aggregation - hematocrit relation shows inter-species differences. Human blood was found to be the most sensitive for hematocrit changes. The more obvious differences could be detected by M 5 s by light-transmission method and amplitude parameter using light-reflection method.

Which remote ischemic preconditioning protocol is favorable in renal ischemia-reperfusion injury in the rat?

BACKGROUND: The optimal timing of remote ischemic preconditioning (RIPC) in renal ischemia-reperfusion (I/R) injury is still unclear. We aimed to compare early- and delayed-effect RIPC with hematological, microcirculatory and histomorphological parameters. METHODS: In anesthetized male CrI:WI Control rats (n = 7) laparotomy and femoral artery cannulation were performed. In I/R group (n = 7) additionally a 45-minute unilateral renal ischemia with 120-minute reperfusion was induced. The right hind-limb was strangulated for 3×10 minutes (10-minute intermittent reperfusion) 1 hour (RIPC-1 group, n = 7) or 24 hour (RIPC-24 group, n = 6) prior to the I/R. Hemodynamic, hematological parameters and organs' surface microcirculation were measured. RESULTS: Control and I/R group had the highest heart rate (p < 0.05 vs base), while the lowest mean arterial pressure (p < 0.05 vs RIPC-1) were found in the RIPC-24 group. The highest microcirculation values were measured in the I/R group (liver: p < 0.05 vs Control). The leukocyte count increased in I/R group (base: p < 0.05 vs Control), also this group's histological score was the highest (p < 0.05 vs Control). The RIPC-24 group had a significantly lower score than the RIPC-1 (p = 0.0025 vs RIPC-1). CONCLUSION: Renal I/R caused significant functional and morphological, also in the RIPC groups. According to the histological examination the delayed-effect RIPC method was more effective.

Micro-Rheological Changes of Red Blood Cells in the Presence of an Arterio-Venous Fistula or a Loop-Shaped Venous Graft in the Rat.

Introduction: In case of kidney failure, hemodialysis is the primary kidney replacement technique. Several vascular access methods used for the therapy, one of which is the arterio-venous fistula (AVF). In the AVF, the blood flow is altered, which can elevate the mechanical stress on the red blood cells (RBCs). This can affect the RBC hemorheological properties, and it can further cause systemic changes. To lower the turbulence and shear stress, we performed a loop-shaped arterio-arterial venous interposition graft (loop-shaped graft) to compare its effect to the conventional AVF. Materials and Methods: Thirty male Wistar were used (permission registration Nr.: 25/2016/UDCAW). The animals were randomly divided into sham-operated, AVF, and loop groups (n = 10/each). The superficial inferior epigastric vein (SIEV) was used to create the AVF and the loop-shaped graft. Blood samples were taken before/after the surgery and at the 1st, 3rd, and 5th postoperative weeks. We measured hemorhelogical, hematological, and blood gas parameters. The microcirculation of the hind limbs was also monitored using Laser Doppler fluxmetry. Results: Hematocrit, RBC count, and hemoglobin decreased by the 1st postoperative week. The erythrocyte aggregation values significantly increased in the fistula group by the 5th week (6.43 ± 2.31 vs. 13.60; p < 0.0001; vs. before operation). At the postoperative 1st week in the loop group, the values showed a significant decrease in RBC deformability. During the maturation period, dominantly at the 5th week, all values were normalized. The operated hind limb's skin microcirculation significantly increased in the sham and loop group by the 1st week (39 ± 10.57 vs. 73.93 ± 1.97 BFU, p < 0.01). This increase wasn't observed in the fistula group probably due to a steal-effect. Conclusion: Unlike in the loop group, in the presence of the fistula, several rheological parameters have changed. The loop-shaped graft had only minimal impact on micro-rheological parameters.

Microrheology, microcirculation and structural compensatory mechanisms of a chronic kidney disease rat model. A preliminary study.

BACKGROUND: Chronic kidney disease (CKD) models are known to study pathophysiology and various treatment methods. Renal dysfunction could influence erythrocytes through several pathways. However, hemorheological and microcirculatory relation of CKD models are not completely studied yet. OBJECTIVE: To evaluate erythrocyte micro-rheology, microcirculatory and structural compensatory mechanisms in a rat model of CKD. METHODS: Female Sprague-Dawley rats were subjected to nephrectomy group (NG, n = 6) or sham-operated group (SG, n = 6). NG rats were subjected to 5/6 nephrectomy in two stages. In SG no intervention was made on kidneys. Hemorheological and hematological measurements were carried out after each stage, and 5 weeks after the last operation. Histological and microcirculatory studies were done on the remaining kidney and compared with sham rats. RESULTS: Serum creatinine increased in NG (p = 0.008), accompanied with decrease of red blood cell count (p = 0.028) and hemoglobin (p = 0.015). Erythrocyte aggregation parameters slightly increased in NG, while the elongation index didn't show significant changes. Microcirculation was intact in the remnant kidney of NG. However, in comparison with SG, the diameter of glomeruli increased significantly (p < 0.01). CONCLUSIONS: Erythrocyte mass was influenced more than micro-rheological properties in this model. The main compensation mechanism was rather structural than at microcirculatory level.

N,N-dimethyltryptamine Prevents Renal Ischemia-Reperfusion Injury in a Rat Model.

BACKGROUND: Ischemia reperfusion (I/R) injury remains one of the most challenging fields of organ transplantation. It is highly associated with the use of expanded criteria donors that might conclude to delayed graft function or early or late graft failure. OBJECTIVE: To investigate the metabolic, microcirculatory parameters, and histologic changes under the effect of N,N-dimethyltryptamine (DMT) in a renal I/R model in rats. METHOD: In 26 anesthetized rats both kidneys were exposed. In the control group (n = 6) no other intervention happened. In 20 other animals, the right renal vessels were ligated, and after 60 minutes the right kidney was removed. The left renal vessels were clamped for 60 minutes then released, followed by 120 minutes of reperfusion. In the I/R group (n = 10), there was no additive treatment, while in I/R + DMT group (n = 10) DMT was administered 15 minutes before ischemia. Blood samples were taken, laser Doppler measurement was performed, and both kidneys were evaluated histologically. RESULTS: Microcirculation (blood flux units [BFU]) diminished in all groups, but remarkably so in the I/R + DMT group. This group compensated better after the 30th minute of reperfusion. The control and I/R + DMT groups had similar BFUs after 120 minutes of reperfusion, but in the I/R group BFU was higher. Tubular necrosis developed in the I/R and I/R + DMT groups too; it was moderated under DMT effect, and severe without. Histologic injuries were less in I/R + DMT Group compared to non-treated animals. CONCLUSION: Histologic changes characteristic to I/R injuries were reversible and microcirculation recovered at the end of 120 minutes reperfusion under the administration of DMT. DMT can be used for renoprotection in kidney transplantation.

Modulation of micro-rheological and hematological parameters in the presence of artificial carotid-jugular fistula in rats.

BACKGROUND: Arteriovenous fistula (AVF) may affect erythrocytes through many pathways (e.g., mechanical, inflammatory). However, these effects haven't been elucidated completely yet. OBJECTIVE: To follow-up the hemorheological and the hematological changes in the presence of artificial carotid-jugular fistula in rats. METHODS: Female Wistar rats were subjected to sham-operated group (SG, n = 6) and to fistula group (FG, n = 10). Under general anesthesia, the right carotid artery and jugular vein were isolated via a neck incision, and in the FG carotid-jugular fistula was performed by microsurgical techniques. Hematological variables, red blood cell (RBC) deformability and membrane (mechanical) stability parameters were determined before operation and on the 1st and 6th postoperative weeks. Density separated samples ('young' and 'old' RBCs) were also tested. RESULTS: In FG group hematocrit, RBC and platelet counts increased gradually to reach highly significant level of increment on the 6th postoperative week. RBC deformability significantly was impaired. The membrane stability test showed lower deformability values after applying mechanical shearing. No significant differences were observed between density separated RBC subpopulations. CONCLUSIONS: The presence of arteriovenous fistula may lead to an increment of RBC mass and impairment of RBC deformability. These changes could be one of the pathways through which the fistula influences the microcirculation.

Renal ischemia-reperfusion-induced metabolic and micro-rheological alterations and their modulation by remote organ ischemic preconditioning protocols in the rat.

BACKGROUND: Pathomechanism and optimal renoprotective protocol for remote ischemic preconditioning (RIPC) have not been completely revealed yet. OBJECTIVE: To investigate micro-rheological effects of early and delayed RIPC in renal ischemia-reperfusion (I/R) in the rat. METHODS: In Control group the left femoral artery was cannulated and the left kidney was gently exposed. In the I/R group 45-minute renal ischemia with 120-minute reperfusion period was monitored. In the RIPC groups a 3×10-minute protocol was applied using tourniquet around the right hind-limb 1 hour (RIPC-1) or 24 hours (RIPC-24) prior to the I/R. Blood samples were taken for testing blood gas, acid-base, metabolic and hemorheological parameters. RESULTS: Lactate and potassium concentration significantly increased in I/R that could be reduced by RIPC, especially in RIPC-24. Creatinine concentration increased further in RIPC groups. I/R and RIPC-1 decreased the pH, RIPC-24 increased. RIPC-24 reduced the drop in base excess. Erythrocyte deformability worsened by renal I/R. In RIPC groups deformability decreased additively. However, RIPC-1 could improve the condition. RIPC-24 showed the highest erythrocyte aggregation values during reperfusion. CONCLUSIONS: Renal I/R worsened metabolic and micro-rheological parameters that could be modulated by RIPC protocols. However, it could not be decided whether the early or the delayed protocol is better.

Carotid-Jugular Fistula Model to Study Systemic Effects and Fistula-Related Microcirculatory Changes.

BACKGROUND: Arteriovenous fistulae impair the distal circulation, but their effects at the microcirculatory level are not well understood. This study presents the carotid-jugular fistula (CJF) as a model to evaluate fistula-related microcirculatory and systemic changes. MATERIALS AND METHODS: Female Wistar rats were anesthetized and divided into a fistula group (FG, n = 10) and a sham group (SG, n = 6). End-to-end anastomosis was performed between the right carotid artery and the jugular vein in the FG. The hemodynamic status was followed for 6 weeks. On the sixth postoperative week, liver and kidney microcirculation was measured using laser Doppler; then microcirculatory changes were assessed after occlusion of the carotid artery. At the end of the experiment, histological samples were taken and the weights of the organs were measured. RESULTS: The heart rate and systolic blood pressure decreased significantly due to the CJF. Laser Doppler showed a reduction in liver blood flow units (BFU) in the FG in comparison with the SG (p = 0.01), and they increased (p < 0.01) after occlusion of the fistula. Kidney BFU showed slight changes only. The comparative morphological study revealed significant increases in heart weight (p < 0.001) and left ventricular hypertrophy (p = 0.008) in the FG. CONCLUSION: Beside hemodynamic and morphologic changes, a CJF causes a deterioration in the microcirculation of the liver rather than of the kidney, but occlusion of the CJF immediately reverses these changes.

Is the early or delayed remote ischemic preconditioning the more effective from a microcirculatory and histological point of view in a rat model of partial liver ischemia-reperfusion?1.

PURPOSE: To compare early- and late-effect remote ischemic preconditioning (RIPC) by analysing the microcirculatory, hemodynamic and histological changes in partial liver ischemia-reperfusion of rats. METHODS: 60-minute partial liver ischemia followed by 120-minute reperfusion was performed without (Control group, n=7) or with preconditioning. In RIPC groups a tourniquet was applied around the left thigh using 3 cycles of 10-minute ischemia/10-minute reperfusion, one (RIPC-1, n=7) or twenty-four hours (RIPC-24, n=7) before I/R. Hemodynamic and microcirculatory measurements were performed before and after ischemia and in 30th, 60th and 120th minute of reperfusion and histological examination at the end of reperfusion. RESULTS: Blood pressure decreased in all groups followed by biphasic changes in Control group. In RIPC groups R120 values returned almost to normal. Heart rate increased in Control and RIPC-1 groups at R120, while RIPC-24 did not show significant changes. Microcirculation of non-ischemic liver stayed constant in Control and showed significant changes in RIPC-24 group, while in ischemic liver elevated by R120 in all groups. RIPC didn't reduce histological alterations. CONCLUSION: Considering the survival and the results, both remote ischemic preconditioning protocols had beneficial effect in hepatic ischemia-reperfusion, however the histopathological findings were controversial.

Is the early or delayed remote ischemic preconditioning the more effective from a microcirculatory and histological point of view in a rat model of partial liver ischemia-reperfusion?

Abstract Purpose: To compare early- and late-effect remote ischemic preconditioning (RIPC) by analysing the microcirculatory, hemodynamic and histological changes in partial liver ischemia-reperfusion of rats. Methods: 60-minute partial liver ischemia followed by 120-minute reperfusion was performed without (Control group, n=7) or with preconditioning. In RIPC groups a tourniquet was applied around the left thigh using 3 cycles of 10-minute ischemia/10-minute reperfusion, one (RIPC-1, n=7) or twenty-four hours (RIPC-24, n=7) before I/R. Hemodynamic and microcirculatory measurements were performed before and after ischemia and in 30th, 60th and 120th minute of reperfusion and histological examination at the end of reperfusion. Results: Blood pressure decreased in all groups followed by biphasic changes in Control group. In RIPC groups R120 values returned almost to normal. Heart rate increased in Control and RIPC-1 groups at R120, while RIPC-24 did not show significant changes. Microcirculation of non-ischemic liver stayed constant in Control and showed significant changes in RIPC-24 group, while in ischemic liver elevated by R120 in all groups. RIPC didn't reduce histological alterations. Conclusion: Considering the survival and the results, both remote ischemic preconditioning protocols had beneficial effect in hepatic ischemia-reperfusion, however the histopathological findings were controversial.

Beneficial effects of remote organ ischemic preconditioning on micro-rheological parameters during liver ischemia-reperfusion in the rat.

BACKGROUND: Remote ischemic preconditioning (RIPC) can be protective against the damage. However, there is no consensus on the optimal amount of tissue, the number and duration of the ischemic cycles, and the timing of the preconditioning. The hemorheological background of the process is also unknown. OBJECTIVE: To investigate the effects of remote organ ischemic preconditioning on micro-rheological parameters during liver ischemia-reperfusion in rats. METHODS: In anesthetized rats 60-minute partial liver ischemia was induced with 120-minute reperfusion (Control, n = 7). In the preconditioned groups a tourniquet was applied on the left thigh for 3×10 minutes 1 hour (RIPC-1, n = 7) or 24 hours (RIPC-24, n = 7) prior to the liver ischemia. Blood samples were taken before the operation and during the reperfusion. Acid-base, hematological parameters, erythrocyte aggregation and deformability were tested. RESULTS: Lactate concentration significantly increased by the end of the reperfusion. Erythrocyte deformability was improved in the RIPC-1 group, erythrocyte aggregation increased during the reperfusion, particularly in the RIPC-24 group. CONCLUSIONS: RIPC alleviated several hemorheological changes caused by the liver I/R. However, the optimal timing of the RIPC cannot be defined based on these results.

Age- and gender-related hemorheological alterations in intestinal ischemia-reperfusion in the rat.

BACKGROUND: Intestinal ischemia-reperfusion (I/R) is a life-threatening clinical disorder. During I/R, the microrheological parameters of blood (red blood cell deformability and aggregation) worsen, which may contribute to microcirculatory deterioration. Age and gender also have a great influence on hemorheological parameters. We aimed to investigate the gender and age-related microrheological alterations during intestinal I/R. MATERIALS AND METHODS: After the cannulation of the left femoral artery, median laparotomy was performed in Crl:WI rats under general anesthesia. In the young control animals there were no other interventions (female n = 7; male n = 7). In the young (female n = 7; male n = 7) and older I/R groups (female n = 6; male n = 6), the superior mesenteric artery was clipped for 30 min, and a 120-min reperfusion period was observed afterward. Blood samples were taken before and at the 30-min ischemia, in the 30th, 60th, and 120th min of the reperfusion. Hematological parameters, erythrocyte deformability, and aggregation were determined. RESULTS: Hematocrit increased significantly in the younger female I/R group. Red blood cell count was higher in male and older animals. In case of white blood cell count, male animals had higher values compared with females. Platelet count elevated in the younger male and older female I/R animals. Red blood cell deformability worsened, mainly in the male and older I/R groups. Enhanced erythrocyte aggregation was seen in all groups, being more expressed in the female I/R groups. CONCLUSIONS: Microrheological parameters show gender and age-related differences during intestinal I/R. These observations have importance in the planning and evaluation of experimental data.

Hemorheological and metabolic consequences of renal ischemia-reperfusion and their modulation by N,N-dimethyl-tryptamine on a rat model.

BACKGROUND: Micro-rheological relations of renal ischemia-reperfusion (I/R) have not been completely elucidated yet. Concerning anti-inflammatory agents, it is supposed that sigma-1 receptor agonist N,N-dimethyl-tryptamin (DMT) can be useful to reduce I/R injury. OBJECTIVE: To investigate the micro-rheological and metabolic parameters, and the effects of DMT in renal I/R in rats. METHODS: In anesthetized rats from median laparotomy both kidneys were exposed. In Control group (n = 6) no other intervention happened. In I/R group (n = 10) the right renal vessels were ligated and after 60 minutes the organ was removed. The left renal vessels were clamped for 60 minutes followed by 120-minute reperfusion. In I/R+DMT group (n = 10) DMT was administered 15 minutes before the ischemia. Blood samples were taken before/after ischemia and during the reperfusion for testing hematological, metabolic parameters, erythrocyte deformability and aggregation. RESULTS: Lactate concentration significantly increased and accompanied with decreased blood pH. Enhanced erythrocyte aggregation and impaired deformability were observed from the 30th minute of reperfusion. In I/R+DMT group we found diminished changes compared to the I/R group (lactate, pH, electrolytes, red blood cell deformability and aggregation). CONCLUSIONS: Metabolic and micro-rheological parameters impair during renal I/R. DMT could reduce but not completely prevent the changes in this rat model.

Effects of aging and gender on micro-rheology of blood in 3 to 18 months old male and female Wistar (Crl:WI) rats.

BACKGROUND: Age- and gender-related alterations of hemorheological parameters have not been completely elucidated to date. Experiments on older animals may give valuable information on this issue. However, the majority of rheological studies have been performed in young rodents. OBJECTIVE: We aimed to investigate the influence of aging and gender on hemorheological parameters in rats. METHODS: Coeval male (n=10) and female (n=10) Wistar (Crl:WI) rats were followed-up over 15 months. Blood samples were obtained from the lateral tail vein at 3, 4, 5, 9, 12, 15 and 18 months of age. Hematological parameters, red blood cell deformability (elongation under shear), osmotic gradient deformability and erythrocyte aggregation were tested. Body weight and the estrus cycle (in females) were also examined. RESULTS: Erythrocyte aggregation showed age- and gender-related variations. Red blood cell deformability was greater in females and gradually decreased over the 15-month period in both genders. Erythrocyte aggregation was greater in male rats at most ages, but did not show consistent changes with age. CONCLUSIONS: The micro-rheological parameters showed age-related alterations with gender differences. The effect of the estrous cycle cannot be excluded in female rats. The results provide reference data for studies of aging in rats and of the mechanism related to age and gender differences in hemorheology.

Intestinal ischemia-reperfusion leads to early systemic micro-rheological and multiorgan microcirculatory alterations in the rat.

BACKGROUND: Intestinal ischemia-reperfusion (I/R) is a potentially life-threatening situation and its pathomechanism is not fully understood yet. OBJECTIVE: To investigate the early micro-rheological, microcirculatory and morphological consequences of intestinal I/R in a rat model. METHODS: CD rats were anesthetized and subjected to Control (n = 7) or I/R (n = 7) groups. Left femoral artery cannulation and median laparotomy were performed. In the I/R group the superior mesenteric artery was clamped for 30 minutes. Blood samples were taken before (Base) and after the ischemia, at the 30th, 60th and 120th minutes of the reperfusion (R-30, R-60, R-120). Hematological parameters, erythrocyte deformability and aggregation were determined. On the jejunum, the liver and the right kidney laser Doppler flowmetry tests were completed. At the end of experiment histological samples were taken. RESULTS: Hematocrit, leukocyte and platelet counts increased during the reperfusion. Erythrocyte deformability worsened versus Control. All erythrocyte aggregation index values of I/R group increased gradually. Intestinal microcirculatory blood flux units (BFU) did not recover completely after ischemia, at R-30 liver BFU values were lower, and kidney values decreased by R-120. Histology showed signs of I/R injury. CONCLUSIONS: Micro-rheological parameters may show early and significant deterioration during the reperfusion that might contribute further to microcirculatory alterations.

Chemically Induced Cell Cycle Arrest in Perfusion Cell Culture.

In contrast to most present methods, continuous imaging of live cells would require full automation in each processing step. As an integrated system that would meet all requirements does not exist, we have established a long-term scanning-perfusion platform that: (a) replaces old medium with fresh one, (b) bypasses physical contact with the cell culture during continuous cell growth, (c) provides uninterrupted photomicrography of single cells, and (d) secures near physiological conditions and sterility up to several weeks. The system was validated by synchronizing cells using serum starvation and butyrate-induced cell cycle arrest of HaCaT cells.