[Effekt of blood flow shutdown on the vein damage when exposed to HIFU].

The purpose. In the study we investigated the impact of the partial blood flow shutdown on structural changes in the rabbit vena cava posterior wall after exposure to high-intensity focused ultrasound (HIFU). Methods. Ultrasound Exposure: frequency of 1.65 MHz, the ultrasound intensity in the focus of 13.6 kW/cm2, the area of the focal spot 1 mm2, continuous ultrasound, exposure for 3 seconds. Results. Immediately after HIFU exposure all layers of the vein wall showed characteristic signs of thermal damage. A week after exposure structural changes in the intima, media and adventitia was minimal in the part of vessel with preserved blood flow, and after 4 weeks the changes were not revealed. A week after HIFU exposure partial endothelium destruction, destruction of myocytes, disorganization and consolidation of collagen fibers of the adventitia were observed in an isolated segment of the vessel, and in 4 weeks endothelium restored and signs of damage in media and adventitia persisted, but were less obvious than in a week after exposure. Conclusion. The shutdown of blood flow after exposure to HIFU promotes persistent changes in the vein wall. Vein compression appears to be necessary for the obliteration of the vessel, when using HIFU-technology.

[NOTHROMBEL EFFECT ON THE FORMATION OF PLATELET-LEUKOCYTE COMPLEXES INDUCED BY THROMBIN].

The effects of the Nothrombel on the formation of platelet-leukocyte complexes (PLCs) induced by thrombin was studied. It was shown, that Nothrombel dose-dependently inhibited the formation of PLCs. Its activity is higher than the activity of the comparison compounds Aspirin. The half maximal effective concentration (EC50) for Nothrombel is 1.75 mMol/mL, for Aspirin is much more than 2.5 mMol/mL. The inhibition mechanism of the PLCs formation by Nothrombel caused by the ability of this drug to inhibit the P-selectin translocation on the platelet membrane, the expression of membrane complex GPIb-IX-V, the mobilization of cytoplasmic calcium in platelets, as well as, apparently, its inhibitory effect on platelet P2Y12 purine receptors.

[Examination of skin autofluorescence for the determination of glycation end-products in patients on chronic hemodialysis].

AIM: To assess the results of determination of glycation end-products (GEPs) by skin autofluorescence (AF) in patients on chronic hemodialysis (HD). SUBJECTS AND METHODS: A device made in Russia was used to estimate skin AF intensity in 40 apparently healthy individuals and in 76 patients treated with chronic HD. While analyzing the findings, comparisons were made in both groups; a relationship between skin AF intensity and clinical and laboratory parameters was also investigated in patients on HD. RESULTS: The intensity of AF in the patients treated with chronic HD proved to be significantly higher than that in the control group. There was a direct correlation of the intensity of AF with age in both groups and that with the duration of dialysis treatment in patients on HD. In patients with coronary heart disease, the intensity of AF was significantly higher than in those without this condition. The intensity of AF directly correlated with the Charlson comorbidity index in the patients on HD. There were no correlations of skin AF intensity with main generally detected laboratory blood indicators, body mass index, and the nature of drug therapy in the patients on HD. CONCLUSION: Tissue GEP levels may serve as a cumulative index of metabolic stress in HD patients. The determination of GEP by measuring the intensity of skin AF may be used to assess prognosis in patients treated with chronic HD.

[NOTHROMBEL EFFECT ON THE EXPRESSION OF MEMBRANE COMPLEX GPIb-IX-V PLATELETS ACTIVATED BY THROMBIN].

The influence of Nothrombel on the expression of membrane complex GPIb-IX-V of platelets activated by thrombin was studied. It is established that Nothrombel reduced thrombin-induced expression of complex GPIb-IX-V on the membrane of the activated platelets. The inhibitory activity of Nothrombel on the expression of GPIb (CD42b) was comparable to its activity with respect to GPIX (CD42a) and is equal to 43 %. With regard to GPV (CD42d) inhibitory effect of the drug was less pronounced and is equal to 22 %. The possible targets for Nothrombel are activation of thromboxane signaling pathway, as well as GPIb-IX-V receptors of platelets itself.

[Applying HIFU for the obliteration of the veins in the experiment ].

The effect of high-intensity focused ultrasound (HIFU) on venous wall structure was studied in the rabbit model. Special setup was developed for ultrasound generation and vessel targeting. Methods. The essential part of the setup is spherical focusing power irradiator with following characteristics: power supply voltage of 25 V, frequency of 1.9 MHz, ultrasound intensity in the focal spot ~8.7 kW/cm2. Results. Single 15-s exposure of the femoral vein to HIFU resulted in partial desquamation of the endothelium, vacuolization of myocyte cytoplasm, misarrangement and coagulation of collagen fibers. Pulsed HIFU (5 pulses for 5 s each) caused protein coagulation in all layers of venous wall (v. cava posterior) as well as the appearance of the areas of fibrinoid necrosis, severe endothelial desquamation, and intimal detachment. HIFU-induced collagen structural changes in media and adventitia of the vein suggest that HIFU exposure resulted in local temperature increase up to ~60°Ð¡. In some experiments, adjacent to the vein muscles were also exposed to HIFU. In this case, edema of the interstitium and muscle fibers was registered, as well as fragmentation and coagulation of some fibers, altered staining patterns and neutrophil infiltration. These changes could be attributed to the development of acute muscle injury (acute fasciitis). Perivascular adipose tissue also demonstrated edema and lipolysis, red blood cell diapedesis, and leukocyte infiltration. Conclusion. The observations on structural changes in the venous wall after HIFU exposure could lay the ground for future experiments on HIFU - mediated obliteration.

[Possibility of the use of the conjugate of indocyanine green with albumin for infrared fluorescent diagnosis of pathological processes in experiment].

An investigation of fluorescent diagnosis possibility in the near infrared range was performed on a rat model of the Pliss lymphosarcoma (30 rats) with the use of indocyanine green (ICG) as a fluorescent marker and photosensitizer. For conju- gates of ICG there were used bovine and human albumins as these proteins in solution strengthened and stabilized fluorescence and in intravenous administration promoted improving diagnosis while the diagnostic contrast after administration during the optimum time was no less than 6. It permitted to easily detect a pathological focus (tumor or inflammation).

[Influence of new N,N'-substituted piperazines on thrombin-induced platelet activation].

We have studied the influence of new N,N'-substituted piperazines with variable nature of the linker between piperazine and aromatic cycles (carbonyl group in VR-0411 versus sulfonyl group in VR-0511) on thrombin-induced platelet aggregation, cytoplasmic Ca2+ mobilization in platelets, and P-selectin exposure on the platelet plasma membrane. The inhibitory effect of VR-0511 on platelet aggregation exceeds the effects of the reference compound aspirin and VR-0411 by 35 and 42%, respectively (p < or = 0.01). The effects of test compounds on the mobilization of cytoplasmic Ca2+ in platelets and P-selectin exposure indicate that VR-0411 and VR-0511 inhibit platelet activation in these tests by 28 and 61%, (p < or = 0.01) and 34 and 58% (p < or = 0.01), respectively. The possible targets for VR-0411 and VR-0511 are thromboxane and inositol triphosphate-dependent (IP3 formation) pathways of activation signal transfer.

[Modeling of different degrees of microvessel laser-induced endothelium damage].

A comparative analysis of rat mesentery micro vascular reactions on thermal impact during radiation to the focused laser irradiation in UV and visible regions of spectrum is made. Local intravascular temperature rise during laser irradiation both impulse (lambda = 337 nm) and continuous (lambda = 532 nm) states causes thrombus formation. The thrombus development that determined by laser irradiation parameters gives a possibility to modulate different degrees of microvessel endothelium damage.

[Endothelial dysfunction and apoptosis at early stage of chronic kidney disease].

AIM: To study changes in apoptosis and endothelial function in patients with chronic kidney disease (CKD) stage I-IIIb (CKDsI-IIIb). MATERIAL AND METHODS: A complex of biochemical, enzyme immunoassay and device investigations was used to examine 128 patients with CKDsI-IIIb. RESULTS: In CKD stage I reduction of endothelium-dependent vasodilation (EDV) was detected in 34% patients, in stage II -- in 52 %, in stage IIIa -- y 52 %, in stage IIIb - in 70%. An EDV decrease was associated with glomerular filtration rate (GFR), a homocysteine level and hemodynamic factors. Elevation of endothelin-1 (ET-1) level was seen in CKDsI in 41 %, in CKDsII - in 54 %, in CKDsIIIa - in 70 %, in stage IIIb - in 83% patients. A negative correlation was observed between the level of ET-1 and GFR and positive - with diurnal proteinuria. A significant rise of annexin A5 concentration versus normal was detected as early as in CKDsI (1,14 +/- 0,68 ng/ml). In CKDsII annexin A5 was 2,61 +/- 0,75 ng/ml, in CKDsIIIa - 3,75 +/- 0,93 ng/ml and in CKDsIIIb - 5,16 +/- 1.01 ng/ml. Negative correlations were found between annexin A5 level and GFR, a maximal growth of volumetric blood flow rate in skin vessels in the acetylcholine test, positive correlations with systolic blood pressure, body mass index. CONCLUSION: The levels of ET-1 and annexin A5 are factors having an independent impact on EDV in patients with CKDsI-II.

[The level of endothelin-1 and reactivity of skin microvessels in patients with early stages of chronic kidney disease].

AIM: To evaluate endothelin-1 (ET-1) levels and to characterize reflex vasomotor reactions of skin vessels in distant exposure to cold in patients with chronic kidney disease (CKD) of stage I and II. MATERIAL AND METHODS: Glomerular filtration rate (GFR) was calculated by MDRD formula for 40 healthy subjects (mean age 39.2 +/- 2.0 years) and 147 CKD patients (mean age 41.4 +/- 1.8 years). All the patients were also exposed to the cold test (a modified variant). RESULTS: Patients with CKD stage I demonstrated a 35.1% fall in blood flow rate (Qas) in response to cold stimulus, patients of stage II--a 42.2% fall, healthy patients--a 19.3%. CKD patients of stage I and II retained a Qas fall for 3 min after exposure to cold, while healthy subjects resumed skin blood circulation immediately after exposure to cold. Blood plasma ET-1 concentration in healthy subjects was 0.239 +/- 0.055 fmol/ml, in stage I CKD patients--0.334 +/- 0.066 fmol/l, in stage II CKD patients--0.422 +/- 0.041 fmol/l. Relationships were found between ET-1 level and GFR (Rs = 0.242; p < 0.05), 24 h proteinuria (Rs = 0.375; p < 0.003) and Qas% in the cold test (Rs = -0.389; p < 0.003) as well as time of recovery of the background Qas (Rs = -0.311; p < 0.003). CONCLUSION: Dysfunction of autonomic nervous system at early stages of CKD may arise by means of activation of ET-1 synthesis in response to enhancement of sympathetic impacts.

[The study of the human complement cascade of proteolysis as a target of laser irradiation].

Samples of human blood plasma were irradiated with the laser beam (lamda=633 nm, P=13 mW, t=20 min) in vitro. In experimental and control (incubated in the dark) samples the complement hemolytic activity was measured. Laser irradiation had minor influence on the duration of lag-period and the rate of complement-dependent hemolysis via classical and alternative pathways; it also did not alter the functional activity of factor B, components C2 and C3. Nevertheless laser irradiation effect was seen in essential reduction of a bystander lysis coefficient. This new fact can elucidate some aspects of the clinical effectiveness of the blood laser irradiation.

[The relationship between ischemic preconditioning-induced infarction size limitation and duration of test myocardial ischemia].

Traditionally infarction size reduction by ischemic preconditioning is estimated in duration of test ischemia. This approach limits the understanding of real antiischemic efficacy of ischemic preconditioning. Present study was performed in the in vivo rat model of regional myocardial ischemia-reperfusion and showed that protective effect afforded by ischemic preconditioning progressively decreased with prolongation of test ischemia. There were no statistically significant differences in infarction size between control and preconditioned animals when the duration of test ischemia was increased up to 1 hour. Preconditioning ensured maximal infarction-limiting effect in duration of test ischemia varying from 20 to 40 minutes.

[Ultrasound-induced myocardial preconditioning: analysis of its effectiveness and mechanisms].

It has been shown that exposure of the isolated rat heart perfused according to Langendorff to therapeutic ultrasound (210 kHz and 0.5-1.5 W/cm2 ) induces a cardioprotective response similar to ischemic preconditioning. This reduces the infarct size and improves the postischemic systolic and diastolic function. The ATP-sensitive K+ channel blocker glybenclamide abolished the protection afforded by ultrasound; in contrast, the free radical scavenger N-2-MPG did not influence the ultrasound-induced cardioprotective response.

[Colon carcinogenesis in rat vs. variable light].

The effect of lighting and melatonin treatment on 1,2 dimethylhydrazine (DMH)-induced colon carcinogenesis was investigated in rats. There was a direct correlation between constant lighting, on the one hand, and the rate of the process, on the other, and an inverse one between light deprivation and melatonin treatment. That presented as changes in rate of tumorigenesis, number of tumors per animal, adenocarcinoma cell differentiation grade, invasiveness and proliferative rate. Our results point to light duration as a significant factor of colorectal cancer progression.

[Role of sodium-calcium exchanger in the myocardial protection against ischemia-reperfusion injury].

Present study was aimed at investigation into the role of sodium-calcium exchanger (NCX) in myocardial ischemia-reperfusion injury and ischemic preconditioning (IPC). Experiments were performed in vivo rat model of regional myocardial ischemia-reperfusion. It was shown that inhibition of reverse mode of NCX with selective blocker KB-R7943 at a dose of 10 mg/kg resulted in significant decrease in occurrence and severity of ischemic ventricular tachyarrhythmias. Furthermore, administration of KB-R7943 caused potentiation of the antiarrhythmic effect exerted by single episode of IPC. However, KB-R7943 exerted no effect on myocardial infarction size nor affected infarction size limitation by IPC. In conclusion, inhibition of reverse mode of NCX conferred significant antiarrhythmic effect against ischemic rhythm disorders but it was ineffective in terms of infarction size limitation.

[Glomerular filtration rate is an indicator of endothelial function at early stages of chronic kidney disease].

AIM: To study effects of glomerular filtration rate (GFR) reduction on endothelial function in patients at early stages of chronic renal kidney (CKD). MATERIAL AND METHODS: Endothelial function of 101 patients with CKD of stage I-III was examined using reactive hyperemia test, dopplerography of skin vessels with ionophoresis of acetylcholin and nitroglycerin, lipidogram parameters, homocistein and annexin A5 levels, intima-media complex thickness of the common carotid artery, echocardiography findings. RESULTS: Cardiovascular complications risk factors were found in all the patients: increased body mass index, arterial hypertension, dyslipoproteinemia, hyperhomocysteinemia. Reduced GFR (under 90 ml/min) is an independent factor of atherosclerosis risk. CONCLUSION: GFR reduction corresponding to CRD of stage II is accompanied with enhancement of apoptosis and development of vasomotor endothelial dysfunction that in combination with risk factors contribute to development of a preclinical atherosclerosis phase.

[The role of gap junction communication in metastatic B16 melanoma in C57BL mice].

The study is concerned with the effects of non-specific blocking gap junction communication with oleamide as well as genesis and spreading of melanoma B16 metastases to the lung in mice C57B1. The blocking exerted no distinct influence on primary tumorigenesis but had a marked effect on metastatic spread. Oleamide treatment during tumor growth led to an increase in area covered by metastases. A correlation was established between metastatic frequency and dosage: 1 mg/kg was followed by an upsurge in frequency of secondary lung tumors while 10 mg/kg--by a drop.

[The role of oxygen free radicals in the mechanisms of local and distant ischemic myocardial preconditioning].

The phenomenon of ischemic preconditioning consists in increase in myocardial tolerance to ischemia after short periods of ischemia and reperfusion of the myocardium (local preconditioning) or a distant organ (distant preconditioning). This study is dedicated to the role of oxygen free radicals (OFR) in the mechanisms of preconditioning; pharmacological inhibition of OFR with N-2-mercaptopropionylglycin, a synthetic anti-oxidant, was used. Mouse experiments demonstrated a reduction in the infarction-limiting effect of local preconditioning as a result of OFR inhibiting. This confirms the hypothesis according to which OFR play an important role in the mechanisms of launching and mediating the protective effect of local preconditioning. On the contrary, application of the same dose of N2-mercaptopropionylglycin does not lead to a significant weakening of the infarction-limiting effect of distant preconditioning caused by 20 min of ischemia and 15 min of reperfusion of the small intestine. Thus, it is unlikely that OFR participate in the realization of the effect of distant preconditioning caused by small intestinal ischemia. The authors discuss hypothetic molecular mechanisms of distant myocardial preconditioning.

[Renal tubular epithelocytic changes in hypercysteinemia and experimental chronic renal failure].

One group of adult male Wistar rats received DL-homocysteine, 13.4 mg/kg body weight every day (an HC-group) while the rats underwent subtotal nephrectomy (a SN-group) and were killed 3 weeks later. Both light and electron microscopies were used to analyze obtained renal specimens. A total loss of the brush border in some proximal tubular (PT) cells and an increase of autophagosomes and emergence of the loci of disorganized cytoplasm were observed in the HC-group, while in the SN-group there was a significant increase in the number and size of secondary lysosomes and of foci of the cytoplasmic disorganization.