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.

[Main indicators of educational activity at the Department of Operative Techniques and Surgical Research at the University of Debrecen between 2000-2013]. / A DE OEC Sebészeti Mutéttani Tanszék oktatási tevékenységének fobb mutatói 2000-2013 között.

The authors provide a review about the main parameters of the gradual and postgradual educational activity of the Department of Operative Techniques and Surgical Research between 2000-2013. In this period of time several new subjects and courses have been introduced. The thematics have been widened, and the educational topics underwent a significant change and development: new teaching videos, revised note-books and a new textbook have been prepared through these years. Further, new training models (surgical training models, phantom and biomodels) have also been evolved. The educational activity of the Department was supported significantly several times (financial, contribution, grants) from the University of Debrecen, partner companies, HEFOP and TÁMOP grants. Infrastructural development in conjunction with the above increased the quality of educational standards in gradual and postgradual education, too. All these changes and developments were presented on various professional meetings and published in relevant journals, as part ofinternal quality control.

Allopurinol prevents erythrocyte deformability impairing but not the hematological alterations after limb ischemia-reperfusion in rats.

The measurement of red blood cell deformability provides a possible method for detecting the effect of ischemia-reperfusion on erythrocytes. In our study the effect of 1-h ischemia-reperfusion with or without allopurinol pretreatment on hematological parameters and red blood cell deformability was investigated in a follow-up experiment of 26 male CD outbred rats that were subjected to unilateral hind-limb ischemia by microvascular clips on femoral vessels for 1 h (IR, n = 6), some rats received allopurinol pretreatment under the same conditions (50 mg/kg, AP + IR, n = 8), others were subjected to sham operation (n = 6), and the rest of animals served as control (n = 6). Measurement of erythrocyte deformability using a bulk filtrometer with special setting of cell suspension hematocrit (1%), and determination of hematological parameters were performed daily for one week. In the IR group, relative cell transit time increased significantly on postoperative days 1 and 2, which was not observed in the other groups. Settings for the measurement of erythrocyte deformability by reducing the blood sample volume gave the possibility of monitoring the resulting changes in rats. Mean corpuscular volume and hemoglobin, platelet count, and platelet volume were higher in the IR and AP + IR groups than in the other groups. In summary, short-term ischemia and reperfusion induced lower red blood cell deformability in the early postoperative period, which could be prevented by allopurinol pretreatment.

[Kidney neovascularization by the greater omentum after pretreatment with omental angiogenic factor]. / A vese neovascularizatiója a nagycseplesz felhasználásával omentális angiogén faktor elokezeléssel.

BACKGROUND: Several diseases may affect the renal artery and the circulation of the kidney. In these cases alternative blood flow should be secured to preserve renal function. There are experimental methods for this, such as omentonephropexy. In this model the new vessels grow into the kidney from the omentum. METHODS: Thirty mongrel dogs were anaesthetized and operated on. The left kidney was exposed, partially decapsulated, then omental angiogenic factor extractum was placed on the renal surface and the greater omentum was fixed there. After 4 weeks the left renal artery was ligated, and further 4 weeks later the right kidney was removed. Hematology tests were performed, urea, creatinine levels were measured and urine samples were tested after each operations. For statistical analysis Mann-Whitney rank sum and Wilcoxon signed rank tests were used. RESULTS: The survival rate was 20%. Significant elevations were observed in serum creatinine and urea levels after each operation, mostly after the third one and in non-surviving animals. Moderate anaemia was also present. CONCLUSION: The efficacy of the neovascularization presented in this study and the survival rate indicate further investigations are necessary in order to explore the mechanism and the dynamics of the vascularization processes.

[The importance of hemorheological examinations in experimental limb ischemia-reperfusion injuries]. / A haemorheologiai vizsgálatok jelentosége kísérletes végtagi ischaemiareperfusiós károsodások kapcsán.

Rheological properties of the blood are determined by several factors and if they change it may be diagnostic for many diseases. It is well-known that during ischemia and reperfusion different free-radical liberating pathways are inducted besides the local physical and metabolical changes. These processes may harm red blood cells by increasing their rigidity and impairing their deformability. In ischemia-reperfusion models measurements of erythrocyte deformability is important. Characteristic alterations were observed in both rat and dog hind limb ischemia-reperfusion with vascular clamping on femoral vessels for 1 or 3 hours. Erythrocyte deformability was significantly impaired on the postoperative 1st-3rd days. The acute limb ischemia-reperfusion experimental models seem suitable for further in vivo rheological studies.

Changes in microcirculation after ischemic process in rat skeletal muscle.

Laser Doppler flowmetry (LDF) is a good method to investigate tissue microcirculation, but it has many standardization and measuring problems. To exclude these effects, we performed a test using LDF on rat skeletal muscle. In 12 CD outbred anesthetized rats, bilateral femoral vessels and the quadriceps femoris muscle were exposed. The left femoral artery and vein were clamped for 1 h by microvascular clips (ischemic side). On the right side, no other intervention was made (control side). An LDF probe was applied on the medial vastus muscle. Short-term occlusions (2-3 s) were performed before and after the 1-h clamping and on the control side while LDF curves were registered. The halftimes of ascending curves on the ischemic side were significantly elongated vs. the condition before clamping (P = 0.0007) or the control side (P = 0.0017). Microcirculatory changes caused by 1-h ischemia were shown by this simple, quick, and well-reproducible test on rat skeletal muscle.