This review presents data on the cellular-molecular mechanisms regulating angiogenesis associated with the vascular endothelium. Existing concepts hold that the control of angiogenesis involves ...activated endothelial cells and their precursors (progenitor cells), which synthesize and release angiogenic molecules with different chemical structures and mechanisms of biological action, but all allowing these cells to control each stage of angiogenesis directly or indirectly. Balanced functioning of the system of molecular stimulators and inhibitors of angiogenesis is particularly important for the brain, as excessive formation of blood vessels, like inadequate development of blood vessels, leads in certain conditions to rapid and irreversible changes in nervous tissue. Post-operative neurorepair cannot occur without adequate reperfusion of the injured part of the brain, which can be supported by timely stimulation of angiogenesis, while intensification of this process in tumors, conversely, has adverse consequences. Tumor growth and metastasis are significantly linked with increases in the level of vascularization of malignant tissue, while blockade of angiogenesis is not infrequently the only productive method of limiting tumor growth. However, we have insufficient knowledge of the mechanisms regulating angiogenesis in the brain at the cellular-molecular level in physiological conditions and pathology, so angiogenic influences do not always produce the expected effect.
A novel electrochemical methods namely standard free anodic stripping voltammetry and anodic stripping voltammetric titration are proposed for determination of dissolved sulfide concentration. 2Ag
+
...+
S
2−
→
Ag
2S reaction is used to provide the information. The anodic stripping voltammetric response of unreacted silver-ions at the glassy carbon electrode is used as analytical signal. Results reliability and accuracy are confirmed by analysis of model solutions, spiked natural and tap waters and recovery study, with a recovery of 100
±
5% (
n
=
7) obtained. The approaches show the detection limit (3
σ
blank) of 2–5
×
10
−10
mol
L
−1 and the relative standard deviation of 2–5% for repeated measurements.
The capillaries containing MMP-2 and its tissue inhibitor TIMP-2 were examined in cerebral cortex and white matter obtained from intact Wistar rats (
n
=5) and the rats with progressing experimental ...renovascular hypertension (
n
=35). In hypertensive rats, the changes in intensity of the immunohistochemical reaction and in the density of capillaries expressing TIMP-2 significantly differed from the corresponding values in MMP-2-positive capillaries, which resulted in pronounced deviation of MMP-2/TIMP-2 index from the control level (especially in cerebral cortex) probably attesting to enhanced risk of complications in cases with arterial hypertension.
Pial arteries of different diameter were studied in intact rats and after 6-month modeling of chronic tobacco smoking in rats. Expression of tachykinin NK1 receptors in pial arteries was studied by ...biomicroscopy and immunohistochemical methods. Chronic tobacco smoking induced considerable reorganizations of the arterial bed. The intensity of changes depended on the diameter of vessels. In small pial vessels that directly participate in the blood supply to the brain, pronounced vasodilatation and enhanced expression of NK
1
receptors in the endothelium mediating the effects of substance P were observed; the number of these vessels also increased. The intensity of the response to tobacco smoke components decreased with increasing vessel diameter.
To study the distribution of MMP-2 and MMP-9 and their inhibitors (TIMP-2 and TIMP-1 respectively) in the brain vascular bed of rats exposed to chronic tobacco smoke.
Localization and expression of ...MMP-2, MMP-9, TIMP-2 and TIMP-1 in the pial branches (I-V order vessels), intracerebral arteries and capillaries of rats exposed to tobacco smoke were studied for 36 weeks. The level of enzymatic activity was assessed by the relative quantity of enzymopositive arteries and amount of fragments per 1 mm
and rate of immunohistochemical reaction. Specific capillary density per mm
of brain tissue and optical density of the immunohistochemical product were calculated.
MMP-2 and TIMP-2 were found in all segments of the arterial course in control animals. In rats exposed to tobacco smoking, the expression of MMP-2 increased only in intracerebral arteries and capillaries while TIMP-2 level decreased. MMP-9 and TIMP-1 were noted only in single vessels, mainly small pial and intracerebral arteries, in intact animals. In rats exposed to tobacco smoke, MMP-9 expression significantly increased in all segments of the arterial course whereas the increase in TIMP-1 was observed mainly in large pial arteries.
In physiological conditions, the dynamic balance between MMP-2 and TIMP-2 maintains basic tissue metabolism. Products of tobacco combustion are inductors of the inducible MMP-9 which promotes morphofunctional changes. The imbalance in MMP-9 - TIMP-1 system causes the degradation of extracellular matrix in different segments of the brain arterial course promoting the development of cerebral dysfunction.
The experiment has determined the characteristic features of callusogenesis, regeneration as well as of receiving resistant to fusariosis of potatoes cell lines in simulated conditions of biotic ...stress. The technologic elements of potato cell selection towards its resistance to Fusarium oxysporum and Fusarium sabucinum were presented. We succeeded in separating the lines which during a 3-year period of research were characterised by a higher resistance point as compared to the original varieties Gurman and Tyras. The plantsregenerants received on the selective medium were characterised by higher resistance (by 10-35 %) to the pathogens action as compared to the regenerants of a control variant. The received lines were estimated on their yield capacity and starch content. The lines deviations on economically valuable indices either increased or decreased as to characteristic value. Herewith, the deviation upward is 25-75 % depending on characteristic. The combination of maximal characteristic values was found in lines 12 and 28 of Gurman variety. The received lines were given to the selection-breeding plot for further testing.
To study an effect of chronic smoking on cerebral hemodynamics and cerebrovascular reactivity in different segments of the arterial system of the brain in men.
Male patients enrolled in the study ...were divided into two groups: controls (n=11) and smokers (n=24) with index 30.7 pack-year smoking history. Haemorheological parameters: viscosity of blood, aggregation of erythrocytes, hematocrit, fibrinogen were evaluated in both groups. Using carotid duplex ultrasound (MyLab 50 Esaote, Italy), intima-media thickness (IMT) of common carotid arteries (CCA) was measured. Parameters of cerebral hemodynamics were evaluated using transcranial Doppler ultrasound (Nicolet Companion Biomedikal, USA). Tests of the cerebrovascular reactivity were used to study arteries of three levels: common carotid arteries, middle cerebral arteries (MCA) and pial arteries.
An increase in erythrocytes, hemoglobin, hematocrit, viscosity of blood, aggregation of erythrocytes and fibrinogen was found in the group of smokers compared to the control group. There were an increase in IMT of CCA by more than 50% and a decrease in the mean flow velocity in CCA in smokers. Also smoking decreased MCA mean flow velocity, but this decrease was 2-3 times smaller than in the common carotid arteries. Vasoconstrictor reactions prevailed in MCA, as indicated by the increase in the peripheral vascular resistance index. An increase in vasospastic reactions in pial arteries in smokers was discovered. At the same time, the vasodilatation reaction was maintained or not significantly reduced in pial arteries.
Chronic smoking is one of the significant factors causing changes in haemorheological parameters, damage of vascular wall, initiation of atherogenesis and disturbance of cerebral hemodynamics. The study of velocity characteristics and peripheral vascular resistance indices in the group of smokers revealed different reactions of different segments of the brain arterial system.
Various reactions of fruit crop species and varieties to the increase in air temperature are noted. The adaptation of fruit plants to overheating is connected with the functioning of protective ...mechanisms, which are particular for each species: the detoxication of ammonia formed during protein decomposition or protection of proteins from destruction (in the plum). The capability of plants to survive high temperatures depends on the genotypic properties of a variety, period of manifestation of the temperature stress factor, and duration of its action in separate years. A universal physiological and biological heat tolerance criterion in fruit crop varieties is the degree of change in protein concentration in plant leaves affected by the stress factor.