Antivibration gloves: effects on vascular and sensorineural function, an animal model.

Anti-vibration gloves have been used to block the transmission of vibration from powered hand tools to the user, and to protect users from the negative health consequences associated with exposure to vibration. However, there are conflicting reports as to the efficacy of gloves in protecting workers. The goal of this study was to use a characterized animal model of vibration-induced peripheral vascular and nerve injury to determine whether antivibration materials reduced or inhibited the effects of vibration on these physiological symptoms. Rats were exposed to 4 h of tail vibration at 125 Hz with an acceleration 49 m/s(2). The platform was either bare or covered with antivibrating glove material. Rats were tested for tactile sensitivity to applied pressure before and after vibration exposure. One day following the exposure, ventral tail arteries were assessed for sensitivity to vasodilating and vasoconstricting factors and nerves were examined histologically for early indicators of edema and inflammation. Ventral tail artery responses to an α2C-adrenoreceptor agonist were enhanced in arteries from vibration-exposed rats compared to controls, regardless of whether antivibration materials were used or not. Rats exposed to vibration were also less sensitive to pressure after exposure. These findings are consistent with experimental findings in humans suggesting that antivibration gloves may not provide protection against the adverse health consequences of vibration exposure in all conditions. Additional studies need to be done examining newer antivibration materials.

Inhibition of bacterial growth and biofilm production by constituents from Hypericum spp.

Biofilm embedded bacterial pathogens such as Staphylococcus spp., Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii are difficult to eradicate and are major sources of bacterial infections. New drugs are needed to combat these pathogens. Hypericum is a plant genus that contains species known to have antimicrobial properties. However, the specific constituents responsible for the antimicrobial properties are not entirely known, nor have most compounds been tested as inhibitors of biofilm development. The investigation presented here tested seven secondary metabolites isolated from the species Hypericum densiflorum, Hypericum ellipticum, Hypericum prolificum, and Hypericum punctatum as inhibitors of bacterial growth and biofilm production. Assays were conducted against Staphylococcus epidermidis, Staphylococcus aureus, clinical methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter baumannii. Five of the seven compounds demonstrated growth inhibition against the Gram-positive bacteria with minimum inhibitory concentrations (MIC) ranging from 1.95 µg/mL to 7.81 µg/mL. Four of the secondary metabolites inhibited biofilm production by certain Gram-positive strains at sub-MIC concentrations.

[Impact of vibration on impulse activity of neurons of ipsilateral medial vestibular nucleus of unilaterally delabyrinthined rats].

Background impulse activity of the neurons of ipsilateral medial vestibular nucleus of unilaterally delabyrinthined rats was studied on different days after operation as well as after 5-day vibration. It was found that in intact animals mean neuron discharge rate is 16.6+/-1.7 Hz. On day 2 after affection it falls to 14.7+/-0.9 Hz and returns to the baseline on day 7 after surgery (16.6+/-1.2 Hz). Vibration impact raises mean impulse frequency to 21.2+/-2.8 Hz. Characteristics and significance of the results obtained are discussed.

[The hypothalamic regulation of the activity of vestibular neurons during exposure to vibration]. / Gipotalamicheskaia reguliatsiia aktivnosti vestibuliarnykh neironov pri vozdeistvii vibratsii.

In acute experiments in rabbits the influence of stimulation of the ventromedial hypothalamic nucleus on the activity of neurons of vestibular Deiters' nucleus was studied under conditions of 15-day exposure to vibration (60 Hz, 0.8 mm, 3 h daily). The mechanisms are discussed which underlie the observed phenomena.

[Responses of different hypothalamic structures to stimulation of the viscero-caudal region of the nucleus of a the solitary tract of the medulla oblongata]. / Reaktsii neironov razlichnykh struktur gipotalamusa na razdrazhenie vistsero-kaudal'noi oblasti iadra odinochnogo puchka prodolgovatogo mozga.

Responses of single units of anterior, ventromedial, lateral and posterior hypothalamus to stimulation of the caudal viscero-receptive region of nucleus tractus solitarius were recorded in anesthetized and immobilized cats. The patterns of the responses were mainly excitatory in all structures under study. The highest degree of reactivity was found for units in the lateral and posterior hypothalamus. According to the latency of the evoked discharges three types of responses were revealed: short (6-12 msec), middle (13-22 msec) and long-latency (22-60 msec) responses. At relatively low frequencies of stimulation the reproducibility was rather poor. Possible projections from nucleus tractus solitarius to the hypothalamus are discussed.

[Neuronal reactions of the ventromedial hypothalamus to stimulation of gastric mechanoreceptors and to the intra-arterial administration of glucose and sodium chloride]. / Reaktsii neironov ventro-medial'nogo gipotalamusa na razdrazhenie mekhanoretseptorov zheludka i na vnutriarterial'noe vvedenie gliukozy i khloristogo natriia.

In anesthetized and immobilized cats, intact and with cut splanchnic nerves ("vagal" animals) of vagal nerves ("splanchnic" animals), high degree of responsiveness of hypothalamic neurons, with prevailing excitatory reactions, was found. The responses were obtained mainly to stimulation of gastric adapting mechanoreceptors. Information from the latters reaches the hypothalamic neurons through splanchnic and vagal afferents. Some hypothalamic mechanosensitive neurons were shown to be gluco- and osmosensitive and thereupon able to integrate both the neural and the humoral informations. The functional role of vagal and splanchnic mechanoreceptors of the stomach in activation of hypothalamic units and the "converging ability" of "visceral" neurons of the ventromedial hypothalamic feeding center, is discussed.

[Response of hypothalamic neurons to different groups of afferent fibers of the subdiaphragmatic vagus nerve]. / Reaktsii neironov gipotalamusa na razdrazhenie razlichnykh grupp afferentnykh volokon poddiafragmal'nogo bluzhdaiushchego nerva.

Responses of single units of posterior, anterior, ventromedial and lateral hypothalamus to stimulation of abdominal trunk of the vagus nerve were recorded in anesthetized cats simultaneously with the action potentials of the cervical region of the vagus nerve. 28.1% of the neurons responded to the stimulation, the pattern of responses being mainly excitatory. Vagal stimulation proved to be more effective for units of the lateral hypothalamus, 47.1% of the excitatory reactions followed stimulation of A gamma delta--B afferents and 40.4%--stimulation of C afferents of the vagus. Topical organization of the projection of these groups of visceral afferents to different regions of the hypothalamus was partially revealed. Responses of some A gamma sigma--B and C neurons to stimulation of vagus and sciatic nerves suggest convergence of visceral and somatic afferents to the "convergence" types of neurons. Some A gamma delta--B and C units, chiefly in the ventromedial hypothalamus, responded only to stimulation of visceral vagal afferents. The sensory properties of "visceral" neurons of the hypothalamus are discussed.

[Development of the hypothalamic-cortical interrelations in the ontogeny of the cat]. / Izuchenie razvitiia gipotalamo-korkovykh vzaimootnoshenii v ontogeneze koshki.

Under chloralose narcosis, employing the evoked potentials method, studies have been made on the projection of the posterior hypothalamus to the frontal cortex in 1-30 days old kittens. The animals were divided into 3 age groups: 1-9, 10-19 and 20-30 days. Studies of the EPs in different points of pericruciate zone showed that these potentials are observed in all the investigated points from the first days of postnatal life. The latent period of responses in the youngest animals varied from 40 to 80 ms, exhibiting insignificant fluctuations depending on the cortical zone investigated. From the very beginning of postnatal life, in the same cortical zone the EPs may be observed in response to stimulation of the ischiadic nerve as well. In older animals, the latent period of the EPs decreases in all the points, the decrease being most significant near the crucial fissure. To the 30th day of postnatal life, the EPs in this zone with respect to their latency and configuration became quite similar to those in adult animals. In the third age period, the latency varies from 6 to 10 ms in the focus of maximum activity; with the removal of the recording electrode from this zone the latent period of the hypothalamo-cortical responses increases up to 30-40 ms. Overlapping of the EPs in response to central and peripheral stimulation was observed at all age periods.

[Chronic liver diseases: secondary thymic insufficiency and immunocorrection with T-activin]. / Khronicheskie zabolevaniia pecheni: vtorichnaia timicheskaia nedostatochnost' i immunokorrektsiia T-aktivinom.

105 patients with chronic diffuse diseases of the liver were examined clinically, biochemically and immunologically. The examination included investigation of serum thymic activity, subpopulation of peripheral blood lymphocytes using monoclonal antibodies, immunoglobulins (A, M, G) and CIC. Thymic activity in the serum was low in chronic persistent hepatitis, much lower in chronic active hepatitis and the lowest in hepatic cirrhosis. Thymic activity correlated with the process activity and compensation, peripheral blood levels of T-lymphocytes, T-helpers, T-suppressors. The conclusion is made on thymic deficiency in chronic diffuse hepatic diseases. Correction of chronic secondary thymic insufficiency with T-activin produced a good clinical response.

[Influence of vibration on the spontaneous neuronal activity of the neurons of the superior vestibular nucleus].

The results of vibration action (5, 10 and 15 daily) on spontaneous neuronal activity of superior vestibular nucleus were studied using software for biological signals. Average histograms and autocorrelograms were drawn up after computerized interspike interval analysis. The results have demonstated that neurons of superior vestibular nucleus have mean frequency 14.0 +/- 1.4 Hz. The results obtained suggest significant reconstruction of spontaneous impulse activity in neurons of the superior vestibular nucleus within postvibration period.

[Postvibration changes in the spontaneous activity of neurons in the medial vestibular nucleus]. / Postvibratsionnye izmeneniia impul'snoi aktivnosti neironov medial'nogo vestibuliarnogo iadra.

The method of computer analyses was used for the research of the spectral changes of spontaneous neuronal activity of the medial vestibular nucleus ander vibration action (5, 10 and 15 daily). On the basis of neurons activity analyses it is possible to conclude that the majority of investigated units of flow and instability figured on different levels. The findings are discussed in respect to special points of functional meaning.

[Approaches to the creation of a model of cerebral thrombocytic microembolism and to research on the effects of drugs]. / Podkhody k sozdaniiu modeli trombotsitarnoi mikroémbolii mozga i issledovaniiu vliianiia na nee lekarstvennykh sredstv.

It is shown that the introduction of collagen into the carotid artery brings forth an increase in perfusion pressure during cat cerebral autoperfusion due to blockade of micro-vessels by platelet aggregates. This increase is of a transitory character and is accompanied by changes in the acid-base balance of the arterial blood towards acidosis. It has been established that papaverine and cavinton (vinpocetine) do not cause recanalization of the blocked microvessels, and in case of verapamil it is of a partial character. The infusion of prostacyclin brings about an almost total recanalization of microvessels and prevents intravascular aggregation upon collagen application. It is concluded that this model may prove useful in the selection of drugs for the pathological therapy of cerebral dysfunctions.

[The effect of stimulation of the amygdala basolateral nuclei on the neuron activity of Deiters vestibular nuclei in rabbits]. / Vliianie stimuliatsii bazolateral'nykh iader mindalevidnogo kompleksa na aktivnost' neironov vestibuliarnogo iadra Deitersa u krolikov.

A modulating character of the amygdala basolateral nuclei effect upon the vestibular sensory system was determined in rabbits [correction of rats]. A mechanism of the descending effect of the amygdaloid complex on the activity of the Deiters nucleus neurons, is discussed.

[Response of the hypothalamic neurons to stimulation of the vestibular nerve and lateral vestibular nucleus in rabbits]. / Reaktsii neironov gipotalamusa na stimuliatsiiu vestibuliarnogo nerva i lateral'nogo vestibuliarnogo iadra u krolika.

Effects of single, double, and rhythmic stimulation upon hypothalamic neurons responding to the 1st excitatory phase of lateral vestibular nucleus stimulation, were studied. The data obtained show that activation of some hypothalamic neurons following stimulation of the lateral vestibular nucleus has a monosynaptic character. The findings suggest that ascending afferents from the lateral vestibular nucleus to the hypothalamus pass via oligo- as well as polysynaptic pathways.

[Inhibitory analysis of the respiration of bacteroids from the nodules of yellow lupine]. / Ingibitornyi analiz dykhaniia bakteroidov iz kluben'kov zheltogo liupina

Oxygen uptake and reduction of C2H2 by bacteroids was found to be inhibited by low concentrations of cyanide and azide. However, oxygen uptake was not completely suppressed even by 10(-3) M KCN. Cyanide-resistant respiration was not inhibited by salicyl-hydroxamic acid, and seemed to be accomplished at the account of autoxidable flavo-proteins. A small light-reversible inhibition of respiration by carbon monoxide was found only in the bacteroids with a high rate of nitrogen fixation. Rotenone, antimycin A, and tenoyltrifluoroacetone inhibited oxygen uptake and methylene reduction. Nitrogen fixation, but not respiration, was inhibited by 2,4-dinitrophenol. An electron-transport chain coupled with phosphorylation is supposed to be built into the membranes of the bacteroids. The activity of peroxidase and cytochrome peroxidase was demonstrated in the bacteroids.

[Enzymatic reduction of legoglobin]. / Fermentativnoe vosstanovlenie legoglobina

During incubation in the buffer bacteroids Rizobium lupini liberate an enzymic system (ferri-Lb-reductase) capable of reducing ferri-Lb and ferri-Mb The hemoproteids reduction required the presence of cofactors (NADPH or NADH). The ferri-Lb-reductase activity was also found in the soluble fraction of nodules. It is assumed that bacteroids ferri-Lb-reductase, maintains Lb in a physiologically active reduced state into vegetable cells of the nodules "in vivo" as well.

[Metlegoglobin reductase from lupine nodules. Purification and properties]. / Metlegoglobinreduktaza kluben'kov liupina. Ochistka Svoistva.

The purification procedure and properties of metlegoglobin reductase from the soluble fraction of lupine (Lupinus luteus L.) nodules and from the proteins secreted by bacteroids Rhizobium lupini in vitro are described. The properties of both forms of enzyme were found to be similar. A metlegoglobin reductase preparation purified 125-fold with a yield of 21% was obtained. The enzyme is strictly specific to the cofactor (NADH). No substrate specificity was revealed. The enzyme reduces oxidized cytochrome c, Mb+, Lb+, Hb+ and exygen. The pH optimum for the enzyme is 7,4. The enzyme is inhibited by p-chloromercurybenzoate. In some properties the enzyme from lupine nodules is close to methemoglobin reductase from the erythrocytes. It was shown that apart from metlegoglobin reductase, bacteroids secrete some other proteins, which is indicative of a close interrelationship between the bacteroids and the plant in a symbiotic nitrogen-fixing system.

[Properties of metlegoglobin reductase from lupin root nodules]. / Svoistva metlegoglobinreduktazy kluben'kov liupina.

The interaction between metlegoglobin reductase from lupin root nodules cytosol and some substrates and inhibitors was studied. The Km values for electron acceptors: dichlorophenol indophenol, potassium ferricyanide, methylene blue and cytochrome c were 5.7 x 10(-5), 2.1 x 10(-5), 1.75 x 10(-4) and 2.5 x 10(-5) M, respectively. The Km value for electron donor NADH was 2.4 x 10(-5) M. Hydroxymercurybenzoate and ethylmaleimide inhibited the metlegoglobin reductase activity; the enzyme activity was also inhibited by NAD. Metlegoglobin reductase was inhibited by quinacrine, which confirmed the flavoproteid nature of the enzyme earlier discovered by the authors. Cytochrome b5 from rabbit liver microsomes can be an electron intermediate during cytochrome c reduction by metlegoglobin reductase. The temperature optimum of metlegoglobin reductase is 40 degrees. The enzyme is comparatively thermostable; and was inactivated by 85% only after 5 min heating at 100 degrees.

[Properties of metlegoglobin reductase from lupine nodules]. / Metlegoglobinreduktaza kluben'kov liupina. Hekotorye svo¿istva.

The purification and properties of metlegoglobin reductase from lupine (Lupinus luteus L.) nodules are described. The purification procedure results in a 1056-fold purification of the enzyme with a total yield of 21%. The enzyme possesses the NADH-diaphorase activity. Metlegoglobin reductase is heterogenous during electrophoresis and isoelectric focusing. Electrophoresis produces two vicinal active bands, while isoelectrofocusing results in four active fractions. The fraction possessing the highest activity has a pI of 4.4. The enzyme is a flavoprotein, in which all flavins are represented by FAD. The molecular weight of the enzyme is 30 000. In some properties metlegoglobin reductase from lupine nodules is similar to methemoglobin reductase from erythrocytes and metmyoglobin reductase from muscles.