The Use of Microencapsulated Autologous Thrombi for Modelling Chronic Thromboembolic Pulmonary Hypertension in Rats.

Here we developed a model of chronic thromboembolic pulmonary hypertension (CTEPH) using repeated intravenous administration of microencapsulated thrombi with a controlled rate of biodegradation. Autologous thrombi encapsulated in alginate microspheres with a diameter of 190±48 µm were intravenously injected to rats 8 times every 4 days. In the comparison group, nonmodified thrombi were injected. After 6 weeks, a significant increase in systolic pressure in the right ventricle, a decrease in exercise tolerance, and an increase in the index of vascular wall hypertrophy were revealed in the group receiving injections of microencapsulated thrombi in comparison with the group receiving nonmodified thrombi and healthy animals. Thus, the developed representative CTEPH model can be used to test promising pharmacological substances.

Influence of the cumulative effect of zoledronic acid on periodontal microcirculation in rats.

PURPOSE: To evaluate the effect of repeated administration of zoledronic acid (ZA) on the development and severity of osteonecrosis of the jaws. METHODS: In the experiment, 36 rats were used, which were divided into 4 groups: group 1 was injected with saline for 6 weeks, group 2 was injected with ZA once, group 3 was injected zoledronic acid for 3 weeks once a week, group 4 was injected with ZA for 6 weeks once a week. While taking medications, the tooth was removed. The volumetric blood flow rate was studied using laser and high-frequency ultrasound Doppler in the area of the periodontium of an extracted tooth in rats with the application of acetylcholine. Bone tissue was examined out using CBCT. RESULTS: In group 2, there was a violation of blood flow in the mucous membrane, bone microcirculation, but no reliable data was obtained in the bone defect in comparison with group 1. In groups 3 and 4, there was significantly disrupted blood flow. This led to an increase of the osteonecrosis (maximum at the 4th group), which was confirmed by data obtained using CBCT. An inverse relationship was observed between the blood flow of bone tissue and the size of the defect after tooth extraction. CONCLUSION: The introduction of ZA in a dose-dependent fashion resulted in impaired endothelial vasodilation and impaired blood flow to extraction sockets. These findings might explain the development of osteonecrosis of the mandible following removal of a first molar.

Disorders of microcirculation in the mechanism of bisphosphonate osteonecrosis: preliminary study in rats.

We investigated the possibilities of angioprotection and the reduction of osteonecrosis in rats that had been given bisphosphonates. In our experiment, 27 rats were divided into three groups: Group 1 was injected with saline; Group 2 was given zoledronic acid for six weeks; and Group 3 was given zoledronic acid for six weeks, with added doses of sulodexide after three weeks. After that we constructed a model of how the teeth should be extracted. The velocity of linear blood flow in the periodontal area of an extracted tooth in rats was studied using laser and high-frequency Doppler ultrasound (with the application of the vasoactive substance acetylcholine 3% for 1min). We evaluated changes in the structure of the bony tissues of the head using computed tomography, comparing the control group with the saline group. A rapid reduction in microcirculation was detected during the use of zoledronic acid for six weeks. A smaller reduction in microcirculation was detected after three weeks of treatment with sulodexide and zoledronic acid. There was a reduction in blood flow in the mucous membranes and, to a greater extent, in bony tissue. Zoledronic acid causes significant impairment of the periosteal blood flow to the mucous membranes because of a complex of disorders, which includes both the cellular component (impaired endothelium-dependent vasodilation of the mucous membrane vessels) and by reducing the intensity of microcirculation in the mucous membranes and bony tissues. Sulodexide, however, improves the restoration of blood flow and reduces the severity of osteonecrosis.

Experimental model of osteonecrosis of the jaw in rats treated with zoledronic acid.

We have examined the development of medication-related osteonecrosis of the jaws (MRONJ) in rats with no previous accumulation of zoledronic acid in the mandible. Ten male Wistar rats (weight 350-400g) were anaesthetised with chloral hydrate 450mg/kg intraperitoneally and the first and second mandibular molars on the left side were extracted. The five experimental rats were given six injections of zoledronic acid 0.18mg/kg over the next four weeks (total dose 1.08mg/kg). Two injections were given at once as an intravenous bolus injection (0.36mg/kg). Then rats were given 4 injections (0.18mg/kg) with 1 week interval over the next four weeks, after which they observed for a further four weeks. The five control rats were injected with saline. At the end of the eighth week, the animals were killed by asphyxiation in a carbon dioxide chamber, and their bone structure was visualised using cone-beam computed tomography (CT) and Galaxis software. We then studied the mandibles histopathologically to investigate the incidence of necrosis and infiltration of inflammatory cells. The cone-beam CT images in the experimental group showed deficiencies in the bone structure in the extracted molar area of the lower alveolar ridge. The histological findings in the mandibles of the group given zoledronic acid showed necrosis and infiltration of inflammatory cells, which were not present in the control group. We conclude that the immediate effect of zoledronic acid on the bone tissue during regeneration is an important factor in the development of MRONJ, in addition to the previously reported effects of the duration of treatment with zoledronic acid.

[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).

[CARDIOPROTFETIVE EFECTS OF NECROSTATIN-7 IN THE RAT MODEL OF PERMANENT CORONARY OCCLUSION].

The cardioprotective effects of necroptosis inhibitor necrostatin-7 were studied in the rat model of permanent coronary occlusion. It was found that intraperitoneal injection of necrostatin-7 at a dose of 14.5 mg/kg 60 minutes prior to permanent left coronary artery occlusion reduced the amount of scar tissue and scar length in the left ventricle on the 21st day after surgery. In addition, pretreatment with necrostatin-7 resulted in decreased plasma level of N-terminal pro-brain natriuretic peptide, which points to the improvement in left ventricular function.

[Effect of intragastric creatine glycine ethylic ether fumarate administration in a rat model of occlusive ischemia].

The aim of the study was to investigate neuroprotective effect of creatine glycine ethylic ether fumarate (creamide). The methods involved intragastric administration of creamide in doses of 30 and 50 mg/kg twice a day for 10 days. Focal 30 minutes cerebral ischemia model by endovascular suture occlusion of the middle cerebral artery in a rat with subsequent reperfusion period for 48 hours was produced. Assessment of creamide stability in gastric juice was performed. Ischemic lesion volume accompanying focal ischemia was visualized and determined. Similar infarction patterns had been found with histological methods. Garcia scale was used for clinical study of neurological deficit in rats. Our data suggest a significant neuroprotective effect of creamide in dosage 50 mg/kg administered twice a day which decreased brain lesion volume produced by ischemic and reperfusion injury.

[Cytoprotective effect of creamide drug in the experimental model of the brain ischemia/reperfusion in rats].

The influence of creatine or its derivates on the cell energy potential may be one of the possibl approaches to induce neuroprotection. Effect of creamide (creatinylglycine ethylic ether fumarate) on the brain injury was studied in the experimental model of the brain ischemia/reperfusion in rats. The experiments were carried out in 14-20 weeks old male Wistar rats weighing 240-300 g, anesthetized by chloral hydrate (430 mg/kg). Creamide was administered intravenously at the doses of 50, 70, 140, and 280 mg/kg. For comparison phosphocreatine was used at the dose of 255 mg/kg. Creamide and phosphocreatine were administered intravenously (in volume of 1 ml within 5 min) 30 min before cerebral middle artery occlusion. Focal cerebral ischemia for 30 min was produced by endovascular suture occlusion with the subsequent 48 h reperfusion period. Creamide administration resulted in dose-dependent decrease of brain ischemic injury. Creamide administered at the doses of 140 and 280 mg/kg was more effective as compared with phosphocreatine (255 mg/kg). The data obtained open new perspectives for further research and development of new creatine-derived drugs with neuroprotective action.

[Amides of creatine: perspectives of neuroprotection].

We evaluated the efficacy of derivatives of creatine and amino acids (CrAA) for decreasing cerebral injury in rats with transient middle cerebral artery occlusion (MCAO). Neuroprotective effects of amides of creatine and glycine (CrGlyOEt), phenylalanine (CrPheNH2), thyrosine (CrTyrNH2), and GABA (CrGABAOEt) were investigated. Brain injury was evaluated on day 2 after transient MCAO using a TTC staining of brain slices. Compared with the MCAO control group, all the CrAms showed decreased cerebral injury (p < 0.05). However CrPheNH2, CrTyrNH2, and CrGABAOEt were toxic after intravenous administration and investigated only after intraperitoneal injection. CrGlyOEt did not show any toxicity at dose of 1 mmol/kg. These data evidenced that creatinyl amides can represent promising candidates for the development of new drugs useful in brain ischemia treatment.

Content of total homocysteine and major aminothiols in rats with experimental renal ischemia.

The contents of total homocysteine, cysteine, and glutathione in blood plasma and tissue of rats with renal ischemia were measured by HPLC. Our study was performed on the "two-kidney, one-clip (0.13 mm)" model. The concentrations of homocysteine and cysteine in blood plasma from treated rats were higher than in sham-operated animals (control; by 36 and 14%, respectively). Homocysteine level in the intact and clipped kidneys of treated rats was 40% higher than in the control. However, no differences were found in homocysteine level in the ischemic and intact kidneys of treated animals. Cysteine concentration in the clipped kidney was lower than in the kidneys of intact and sham-operated animals (by 1.6 and 1.5 times, respectively). Glutathione concentration in the ischemic kidney did not differ from the control. No differences were revealed in the content of aminothiols in liver samples from rats of the treatment and control groups. Our results suggest that functional inactivation of one kidney is accompanied by impairment of homocysteine catabolism (trans-sulfonation).

[Effect of hepatoprotector remaxol infusion on liver function in obstructive jaundice model in rats].

Remaxol is a new infusion hepatoprotector that contains succinic acid, inosine, methionine and methylglucamine. The hepatoprotective effect of remaxol on the liver function has been studied on the model of obstructive jaundice in rats, on the terms of one and two weeks after ligation of the common bile duct (M. A. Aller, et al., 2004). Sixty rats were randomly divided into six groups: sham-operated rats with cholestasis, 0.9% NaCl treated rats with cholestasis, and remaxol treated rats with cholestasis, all on the one week (per os n=10) and two weeks (n=10) terms. Remaxol was injected into the tail vein in a dose of 1 ml/100 g during the first week after the induction of cholestasis. The rats were removed from the experiment after one and two weeks of postoperative period, respectively. The size and weight of the liver and the degree of ascites were measured, and the blood samples were taken to analyze for bilirubin, alkaline phosphatase, gamma-glutamyl transpeptidase, alanineaminotransferase, aspartataminotransferase. Morphological changes in the liver were also studied. The biochemical parameters of blood and morphological evolution of tissue of liver in both one and two weeks after the induction of cholestasis showed a significant hepatoprotective effect of remaxol.

[Plasma membrane focal defects in structurally normal cells].

The technique of perfusion fixation through the rat kidney vasculature was modified to ensure the highest possible level of cell preservation close to that under in vivo conditions. Electron microscopic analysis of the tissue specimens treated in such a way revealed local defects of the plasma membrane in a number of cells than that otherwise looked normal. These findings together with the evidence for reparability of such defects and some data on the purely artificial nature of certain alterations should be taken into consideration in order to avoid misinterpretations while diagnosing the biopsy specimens.

[The significance of investigation of the endothelium function in diagnosis and assessment of effectiveness of treatment of infective endocarditis].

The complex state of the endothelium function was studied in 25 patients with infective endocarditis in the preoperative and early terms after surgery. A reliable elevation of all indices of endothelium dysfunction independent of the localization of the formed heart disease was detected. Against the background of operative treatment reliable changes demonstrating an improved functional state of the endothelium were noted in the early postoperative period.

Effect of pancragen on blood glucose level, capillary permeability and adhesion in rats with experimental diabetes mellitus.

The effects of tetrapeptide pancragen (Lys-Glu-Asp-Trp-NH2) on blood glucose level and permeability and adhesion of mesenteric capillaries were studied in Wistar rats with experimental streptozotocin-induced diabetes mellitus. Oral pancragen produced a pronounced hypoglycemic effect during treatment. Intramuscular pancragen normalized the adhesion of mesenteric capillary endothelium, but did not modify capillary permeability. The results indicate homeostatic and endothelioprotective effects of pancragen during the early period of diabetes mellitus.

[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.

[Effect of He-Ne laser irradiation on the functional activity of smooth muscle cells in the portal vein]. / Vliianie izlucheniia He-Ne lazera na funktsional'nuiu aktivnost' gladkomyshechnykh kletok vorotnoi veny krys.

Irradiation of the rat portal vein's fragments with the He-Ne laser for 3, 5 and 10 minutes reduced the fragments tone by half. Frequency of phasic and tonic contractions did not change, their amplitude, however, increased by neatly 40% as compared with the initial level. The NO synthase blocker N-nitro-L-arginine administered prior to the irradiation had no effect on the above parameters. The data obtained suggest that the decrease of the vessel tone is due to production of the EDRF and cGMP. The increase in the amplitude of phasic and tonic contractions of the vein's smooth muscle cells is associated with an increased Ca++ entry in each contraction cycle.

[Effects of parathyroid hormone and parathyroid hypertensive factor on myocardial mechanical properties in normotensive rats]. / Vliianie paratireoidnogo gormona i paratireoidnogo gipertenzivnogo faktora na mekhanicheskie svoistva miokarda normotenzivnykh krys.

After a 10-minute incubation, both the parathyroid hypertensive factor (PHF) and parathyroid hormone (PTH) reduced myocardial contractility and accelerated myocardial relaxation. Effects of the PTH and PHF on myocardial inotropic characteristics were of opposite directions.