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It was shown that tobacco leaf treatment with 100 mM H₂0₂ increased their content ofendogenous H₂0₂ and activities of catalase and hydrolases (acid phosphatase, proteases, and RNase) and also caused'various chang- es in the cell structure. In this case, programmed cell death (PCD) occurred in some cells, which was ob- served as chromatin condensation, cytoplasm collapse, etc. In the meantime, many cells displayed organelle activation rather than PCD. It is suggested that cells that undergo H₂0₂-dependent PCD release signaling molecules inducing protective mechanisms against oxidative stress in neighboring cells not exhibiting PCD.

The activity of hydrolases (protease, RNase) in uninfected and tobacco mosaic virus-infected tobacco leaves of the Samsun variety, untreated and treated with disodium salt of 2-acetyl-4-hydroxycarbonyl-methylthio-5-chlorocyclopent-4-en-1,3-dione (DS), was determined. It was shown that treatment of leaves with this compound significantly increased the activity of hydrolases in them compared to untreated leaves. In infected leaves treated with DS one day before infection, along with an increased level of hydrolases, one revealed more viral particles exposed to destructive changes in infected, rather than untreated, leaves. It is assumed that the DS-caused activation of hydrolases promotes the destruction of viral particles and is therefore one of the cell defense mechanisms induced by this compound that prevents the intracellular accumulation of virus.

Effect of chitosan on the mesophyll cell ultrastucture and activity of hydrolases in leaves of tobacco cv. Samsun was studied. It was shown that, in many cells, chitosan treatment stimulated the protein-synthesizing apparatus (nucleolus dimension and amount of both mitochondria and rough endoplasmic reticulum membranes increased) and, at the same time, caused some activation of lytic compartment expressed in the stimulation of the formation of dictyosomes, smooth ER elements and cytoplasmic vacuoles, which are all prominent constituents of this compartment. In biochemical experiments, it was established that chitosan substantially enhanced activity of hydrolases (acid phosphatase, RNase, proteases) in the leaves as compared to untreated leaves. In some cells chitosan treatment caused considerable destructive changes (condensation of nuclear chromatin, collapse of cytoplasm and so on) that can be classified as a result of programmed cell death development.

The activities of hydrolases (acid phosphatase, RNase, and proteases) in healthy and tobacco mosaic virus-infected leaves of Nicotiana tabacum L. var. Samsun, both untreated and treated with polysaccharides (PS) (1,3;1,6-β-D-glucan, fucoidan, and κ/β-carrageenan), were determined. The PS lead to substantial increase in the hydrolase level. The percentage of viral particles undergoing destructive change also increases in leaves treated with PS 24 h before infection. We suppose that the PS-mediated hydrolase activation promotes intracellular destruction of the viral particles and, thus, comprises one of the PS-induced protective mechanisms limiting intracellular viral accumulation.

Ultrastructural examination of tobacco mosaic virus-induced local lesions developing in leaves of Datura stramonium plants demonstrated that, in the central area of the lesions, the cell response to viral invasion was not uniform. Most cells exhibited an acute hypersensitive reaction and underwent rapid and complete necrosis. However, some cells, despite considerable virus accumulation and immediate contact with completely collapsed cells, maintained a certain degree of structural integrity. Analysis performed showed that the proportion of collapsed and uncollapsed cells in the lesion centre 3 to 5 days after infection did not change essentially. These data suggest that the absence of hypersensitive response in some cells in the lesion centre is not due to an early stage of infection but is likely caused by cell tolerance of the virus.

Influence of chitosan on the accumulation and state of tobacco mosaic virus (TMV) in the mesophyll cells of Nicotiana tabacum L. var Samsun leaves in early period of infection development (3 days after infection of leaves) has been studied. The virus accumulated in the cells of the leaves treated for 24 h before infection with chitosan to a lesser degree than in the control cells. The chitosan affected the formation of TMV-specific granular and tubular inclusions which are known to consist of the viral replicase components. Three days after infection of the leaves treated with the chitosan, a typical sign of the infection development was the predominant formation of granular inclusions which are known to appear at the early stages of TMV replication. The infected cells of the leaves untreated with chitosan contained mainly tubular inclusions which had been shown previously to be formed from granular ones at the last stages of the infection process. This indicates that chitosan treatment of the leaves leads to a delay of the development of infection. In phosphotungstic acid-stained suspensions obtained from the infected leaves, abnormal (swollen and "thin") TMV particles were observed along with normal ones. The appearance of abnormal virus particles seems to be caused by virus-induced activation of intracellular lytic processes. The most lytic activity in the infected cells as well as the highest number of abnormal viral particles was observed under the chitosan action. Therefore, it appears that chitosan-mediated stimulation of lytic processes causing destruction of TMV particles may be one of the protective mechanisms limiting virus accumulation in cells.

The effect of kappa/beta-carrageenan from red alda Tichocarpus crinitus on the development of a potato virus X (PVX) infection in the leaves of Datura stramonium L. has been studied. The treatment of leaves with carrageenan stimulates a protein synthesis in the cells, causing an increase in the size of nucleoli and in the number of mitochondria and membranes of the granular endoplasmic reticulum. At the same time, such treatment slightly stimulates lytic processes, causing an increase in the number of agranular endoplasmic reticulum cisterns, dictyosomes, and cytoplasmic vacuoles and the formation of cytoplasmic zones, transparent to electron microscopy. The carrageenan-induced stimulation of lytic processes results in the destruction of viral particles and can be considered as one of the defense mechanisms, preventing the intracellular accumulation of viruses. The carrageenan-stimulated formation of PVX-specific laminar structures, able to bind viral particles and, therefore, prevent their intracellular translocation and reproduction, represents another carrageenan-induced mechanism of the antiviral defense in plant cells.

The effect of disodium salt of 2-acetyl-4-hydroxycarbonylmethylthio-5-chlorocyclopent-4-en-1,3-dione on development of the infection caused by tobacco mosaic virus in the leaves of two Nicotiana tabacum L. cultivars--an oversensitive cultivar Xanthi-nc and systemically affected Samsun--was studied. The results suggest that this compound interferes with reproduction of the virus. This antiviral displayed the highest activity when applied in a mixture with the virus, presumably due to its action on both the plant and the virus.

Influence of fucoidan from brown alga Fucus evanescens C. Ag. on the development of infection induced by potato virus X (PVX) in Datura stramonium leaves was studied. It as been shown that 24 h after the treatment of the leaves with fucoidan and following infection of them with PVX the accumulation of virus particles in infected cells during early infection period was substantially less than that in untreated control. Using ultrastructure-morphometric analysis, it has been established that fucoidan treatment increases at protein-synthesizing capability of cells (nucleolus dimension, amount of mitochondria and rough endoplasmic reticulum membranes become increased). At the same time, the fucoidan treatment causes some activation of lytic compartment which leads to destruction of virus particles and, therefore, might be considered as one of fucoidan-dependent protective mechanisms limiting virus accumulation in cells. Fucoidan stimulation of the formation of PVX-specific laminated structures capable of virus particles binding is possibly another induced antiviral cell mechanism, preventing from virus reproduction and transposition.

The influence of kappa/beta-carrageenan from red marine alga Tichocarpus crinitus on the development of tobacco mosaic virus (TMV) infection in Xanthi-nc tobacco leaves was studied. It was shown that the number of necrotic lesions on the leaves inoculated with the mixture of TMV (2 microg/ml) and carrageenan (1 mg/ml) was reduced by 87%, compared to the leaves inoculated with the virus only. The suppression of virus infection was also observed when leaves were treated with carrageenan 24 h before or 24 h after leaf inoculation with TMV; however, in these cases, suppression was less evident than after inoculation with the virus-polysaccharide mixture. It is supposed that the antiviral activity of carrageenan applied together with TMV may be explained by its action not only on the plant but also on the virus itself. The inhibitory effect of carrageenan pretreatment can be explained by its favorable effect on tissue resistance to infection. The suppression of this resistance by actinomycin D indicates that carrageenan functions via its action on the cell genome.

The influence of cyclopentane beta,beta'-triketones on the ultrastructure of root cap meristematic cells of Cucumis sativus L. under inhibition of root growth by these compounds was studied. It was shown that treatment of the seedlings by these substances at the concentration of 100 microg/ml caused, on the one hand, stimulation of protein-synthesizing apparatus (increase in the nucleolus size and in the number of mitochondria and rough endoplasmic reticulum membranes) and, on the other hand, stimulation of lytic processes. The fact that the used compounds, causing inhibition of the seedling growth, do not suppress but stimulate protein-synthesizing activity of the cells, according to existing concept, testifies to the compound-mediated induction of the cell resistance to unfavourable factors. Consequently, these compounds, in contrast with growth inhibitors suppressing cell metabolism completely, possess properties peculiar to retardants, growth inhibitors valuable for crop production.

Transgenic tobacco plants (Nicotiana tabacum cv. SR1) expressing extracellular pancreatic ribonuclease from Bos taurus and characterized by an increased level of ribonuclease activity in leaf extracts were challenged with tobacco mosaic virus. The transgenic plants exhibited a significantly higher level of protection against the virus infection than the control non-transformed plants. The protection was evidenced by the absence (or significant delay) of the appearance of typical mosaic symptoms and the retarded accumulation of infectious virus and viral antigen. These results demonstrate that modulation of extracellular nuclease expression can be efficiently used in promoting protection against viral diseases.

The fragmentation of the biologically active 1,3;1,6-beta-D-glucan Antivir by endo-1,3-beta-D-glucanase LIV from crystalline styles of the marine mollusk Spisula sachalinensis was carried out. It was found that low molecular mass oligomers possessing a stabilizing effect on membranes and anti-viral activity against tobacco mosaic virus appeared in the process of enzymatic hydrolysis of Antivir. Biological activity of 1,3;1,6-beta-D-glucooligo- and polysaccharides was found to be associated with molecular mass (polymerization degree (n) not less than 14) and with presence of intralinked beta-1,6-connected monosaccharide residues. Probably, decrease in molecular mass is compensated by increase in number of intralinked beta-1,6-connected monosaccharide residues.

The influence of culture conditions and plasmids on immunoglobulin (Ig)-binding activity of two isogenic strains of Yersinia pseudotuberculosis (plasmid-free strain 48(-)82(-) and strain 48(+)82(+) bearing plasmids pYV48 and pVM82) was studied. The highest activity was observed in the bacteria grown on glucose-containing liquid medium in the stationary growth phase. The Ig-binding activity of the bacteria cultured on the liquid medium at pH 6.0 was about 1.5-fold higher than that of the bacteria grown at pH 7.2. Expression of the Ig-binding proteins (IBPs) was most influenced by temperature of cultivation. The IBP biosynthesis was activated in the bacteria grown at 4 degrees C and markedly decreased in those grown at 37 degrees C. The Ig-binding activity of lysates from the bacteria was caused by proteins with molecular weights of 7-20 kD. The activities of the plasmid-free and plasmid-bearing Y. pseudotuberculosis strains (48(-)82(-) and 48(+)82(+), respectively) were analyzed, and the plasmids were shown to have no effect on the IBP expression and biosynthesis, which seemed to be determined by chromosomal genes.

It is shown that considerable amount of virus particles accumulates in the parenchymal cells infected with any of strains of tobacco mosaic virus (TMV) isolated from affected plants of papper (TMV-p), tomato (TMV-t), eggplant (TMV-e). Along with normal, abnormal (swolled and "thin") virions were found that testifies to their destruction. In reply to infection, activation of the lysosomal compartment was observed in the cells that expressed in the formation of cytoplasmic vacuoles, dyctiosomes, smooth endoplasmic reticulum elements, different vesicles, mitochondria with invaginations, multivesicular bodies. It is established that the investigating strains, in dependence on degree of stimulation of lysosomal compartment and development of intracellular lytic processes causing the destruction of virus particles and cellular structures, may be arranged as follows: TMV-p, TMV-e, TMV-t.

A comparative study was made of the ultrastructure of parenchyma leaf cells of different soybean varieties systemically infected with soybean mosaic virus (SMV). It has been shown that virus accumulation and formation of virus-specific cylindrical inclusions (CIs) occur in the infected cells, in addition to intracellular changes showing stimulation of lytic processes, such as activation of smooth endoplasmic reticulum and Golgi apparatus, formation of cytoplasmic vacuoles, cytosegresomes, myelin-like bodies, different disturbances in the structure of cell organelles. Many infected cells demonstrated microbodies with invagination in which cylindrical inclusions were often found showing signs of destruction. It is suggested that such microbodies possess autophagic activity towards CIs. A possible relation of the observed virus-induced ultrastructural cell changes with the degree of SMV affection of investigated varieties is discussed

A study was made of the ultrastructure of root cap meristematic cells in the seedlings of Cucumis sativus L., whose growth was inhibited by the action of 2-acetyl-4-metylcyclopent-4-en-1,3-dione (AMCD). It is shown that the treatment of seeds by this substance at a concentration of 100 microg/ml leads to the main root inhibition by 73% and, as compared to the control, causes the highest changes in mitochondria that do not reach normal dimensions and undergo degeneration. AMCD caused significant changes in the cell walls that in test samples unusually became electron-dense. Deposits of osmiophylic substance, presumably consisting of terpenoid-like compounds, were often found in the cytoplasm of treated cells as well as in the extracellular space. In many cells, plasmalemma and amiloplast membranes underwent destructive changes. We discuss a possible relation between inhibitory effect of AMCD on the root growth, and its influence on the ultrastructure in investigated cells.

Wide use of angiotensin-converting enzyme (ACE) inhibitors in clinical settings is to a certain extent associated with a small number of side effects developing after taking the above medicines. The most prominent ill effects of ACE inhibitors include hypotension, acute renal impairement in those patients presenting with stenosis of the renal artery or manifest circulatory insufficiency, hyperpotassemia developing because of taking potassium-storing diuretics; cough, Quincke's edema, headache, syncope, orthostatic hypotension, nausea, diarrhea, skin eruption.

Overall sixty patients with hypertensive disease were examined for clinical effectiveness of the prolonged-action inhibitor angiotensine-converting enzyme renitek (enalapril maleate, MJD). The treatment schedule included placebo over two weeks, renitek as monotherapy, 20 mg daily, over 6 weeks, if the patients failed to derive any benefit from the therapy, they were placed on a 4-week combined therapy of renitek plus hydrochlorothiazide. Renitek was found to dispel cardialgias, reduce frequency of attacks of cardiac angina. In the hemodynamic structure, a positive inotropic effect was identified as was reduction of energy expenditure of the myocardium, total peripheral vascular resistance, diminution of post- and preloads on the myocardium, with the mass of the left ventricular myocardium growing less.

The authors developed a system of adaptive bioregulation based on the principle of biological feedback. Sixty hypertensive patients with the initial forms of cerebrovascular disturbances and 30 clinically healthy subjects were examined. Adaptive bioregulation is successfully realized in the technical system with a visual control of changes in the REG area. The treatment is associated with normalization of the tonus, vessel blood filling, arterial pressure and clinical status of patients. Adaptive bioregulation may be one of the methods of treatment of patients with cerebrovascular pathology. The effect of its use is determined by the duration and nature of the disease.