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One of the most common ways to reduce vibration in aircraft engines is the use of damping devices. Squeeze-film dampers are the dampers most widely used in aircraft engine designs. The efficiency of squeeze-film dampers is determined by their damping capacity which depends, among other parameters, on the static pressure of oil supply to the damper. This article proposes a method for calculating the static pressure in the feed groove of a hydrodynamic damper depending on the geometric size of the end gap and the value of the lubricant supply pressure. The parameters influencing the static pressure in the damper end gap are determined. Calculations are performed for different values of a hydrodynamic damper end gap, the number and diameter of the supply ports. All calculations presented in the article were performed for a short squeeze-film damper with end gaps and throttles. For comparison of parameters, the dynamic pressure was also calculated for a long squeeze-film damper. It was shown that the size of the end gap has the strongest impact on the pressure in the groove of a squeeze-film damper. It was also shown that the dynamic pressure in the gap may be significantly higher than the static pressure of supply, and failure of the lubricating film may result. In addition, it was also shown that the size of the damper end clearance affects the lubricant flow through the damper.

The article describes a method for experimental evaluation of the stiffness of an elastic damper ring. A thin-walled low-stiffness ring with uniformly distributed smooth protrusions on the inner and outer surfaces acts as a damper ring. Despite the widespread use of such a design in domestic and foreign mechanical engineering, control of the characteristics of this element and, accordingly, of the support as a whole remains quite difficult. A numerical model was developed, the reliability of which is confirmed by analytical calculations. To check the data obtained by numerical calculations, a special device was designed, which was installed on the galdabini tensile testing machine, where a series of measurements was carried out. Analysis of the data obtained showed a significant difference between the numerical, analytical and experimental data, which can be explained by the discrepancy between the equipment used and the boundary conditions of the theoretical model. The parameters of the device were selected in such a way that its rigidity was much higher than the rigidity of the elastic ring under study. The paper describes the improvement of both the design of the device and the method for determining the stiffness of the elastic ring of the damper using the specified measuring equipment. After making corrections, the obtained data on the scatter of the stiffness of the elastic ring are in good agreement with the analytical and numerical dependence, which makes it possible to use the data of the latter to refine the analytical methods in the future

The article presents the results of monitoring the rotor vibration occurring in gas-pumping units. An assessment of the effect of vibration loads on seal leakage has been carried out. The maximum amplitudes and frequencies of vibration of rotors of gas-pumping units under operating conditions have been determined. A dynamic model of a "dry" seal is proposed, in which axial, angular and bending vibrations of the seal rings are realized. The theoretical definition of the rotor vibration parameters admissible for the operation of "dry" compaction is carried out.

A method for measuring the precise geometric shape of a flexible elastic ring of a damper of a gas-turbine engine bearing is described. The ring stiffness is estimated analytically with account for the real measured geometry. A comparison with the experimental data is carried out. The recommendations on the numerical model with a real press fit of a flexible ring in the bearing are provided.

Using computer analysis, a minimal sequence of Arg136-Asn137-Trp138-Asp139 that can bind to IgE C3 and C4 fragments was determined for the high-affinity receptor FcɛRI, a key protein of IgE-dependent allergic reactions of the immediate type. A number of peptides containing the Arg-Asn-Trp-Asp sequence were proposed as model analogues of the FcɛRI receptor. It was shown that these peptides manifested immunobiological effects and bound to IgE. The peptides were demonstrated to bind to IgE serum antibodies specific to the Dermatophagoides pteronyssinus allergen isolated from plasma of patients with allergic bronchial asthma.

A problem of increasing free power turbine (FPT) service life at the expense of a change to sliding bearings is considered. The differential equations for the rotor motion are derived with account for its design features. Also presented are the calculated data on forced vibrations of the system and the utility of FPT support updating is analyzed.

High-affinity receptor FcepsilonR1 is a key substance which participates in IgE-dependent allergic reactions of immediate type. A minimal sequence Arg136-Asn137-Trp138-Asp139, which takes part in binding with C3 and C4 fragments of IgE was determined by methods of computer analysis. As possible analogs of FcepsilonR1 receptor, capable of binding to Fc-fragment IgE, a number of peptide compounds containing this sequence were proposed. Biological researches have shown that these peptides possess immunobiological effect and bind to IgE. Studied the ability of peptides to bind with IgE class serum antibodies specific to allergen Dermatophagoides pteronyssinus in patients with allergic bronchial asthma.

This review deals with information on the relationship of the immunity system and the lipid transport system. The data of literature and the results obtained by the authors indicated that an elevated level of cholesterol in the blood serum is associated with the increased activity of the immunity system. On the one hand, lipids and their metabolites produce an immunomodulating effect and, on the other hand, biologically active molecules, synthesized by immunocompetent cells in the process of their activation and proliferation, regulate lipid metabolism.

Beta-oxidation of acyl-CoAs in mammalian peroxisomes can occur via either multifunctional enzyme type 1 (MFE-1) or type 2 (MFE-2), both of which catalyze the hydration of trans-2-enoyl-CoA and the dehydrogenation of 3-hydroxyacyl-CoA, but with opposite chiral specificity. Amino acid sequence alignment of the 2-enoyl-CoA hydratase 2 domain in human MFE-2 with other MFE-2s reveals conserved protic residues: Tyr-347, Glu-366, Asp-370, His-406, Glu-408, Tyr-410, Asp-490, Tyr-505, Asp-510, His-515, Asp-517, and His-532. To investigate their potential roles in catalysis, each residue was replaced by alanine in site-directed mutagenesis, and the resulting constructs were tested for complementation in a yeast. After additional screening, the wild type and noncomplementing E366A and D510A variants were expressed and characterized. The purified proteins have similar secondary structural elements, with the same subunit composition. The E366A variant had a k(cat)/K(m) value 100 times lower than that of the wild type MFE-2 at pH 5, whereas the D510A variant was inactive. Asp-510 was imbedded in a novel hydratase 2 motif found in the hydratase 2 proteins. The data show that the hydratase 2 reaction catalyzed by MFE-2 requires two protic residues, Glu-366 and Asp-510, suggesting that their catalytic role may be equivalent to that of the two catalytic residues of hydratase 1.

A new quantitative method for the determination of the DNA-se activity of bacteria, based on the prevention of the clot formation of DNA with rivanol under the action of microbial DNA-ses, has been developed. The sensitivity of this method is 0.005-0.01 units of activity (1-2 ng) of the enzyme in a sample for 1 hour of incubation; the variation coefficient of the method is 8-9%. The use of this method has made it possible to reduce the time of the identification of S.aureus by 2-3 days in comparison with the commonly used methods. As revealed on the model of differentiation between S.aureus and S.epidermidis, the methods of multivariate statistical analysis (dispersion, discriminant, cluster methods) may find wide application for the discrimination of bacteria. They are supposed to be used for the interspecific identification of coagulase-negative staphylococci.

The content of insoluble guanine fractions originating from micromites in specimens of house dust, collected in the dwellings of 15 healthy persons with no signs of allergy and 64 patients with atopic bronchial asthma (ABA), was studied. The content of these fractions in house dust in the dwellings of ABA patients was significantly higher than that in house dust in the dwellings of healthy persons (0.76 +/- 0.119 in comparison 0.31 +/- 0.040, p0.05). A high content of guanine was detected in house dust of the dwellings of 74.1% of ABA patients and 33.3% of healthy persons, which was indicative of the importance of mite contamination in the formation of ABA.

The intravenous injection of 3 beta-(2-hydroxy-2-[3H]ethoxy)cholest- 5-ene into rats with the cannulated common bile duct resulted in the primary accumulation of radioactivity in liver (24%) and spleen (12%) tissues, bile (7%), and blood serum (15%) after 3 hours. The distribution of 3 beta-(2-hydroxy-2-[3H]ethoxy)cholest-5-ene throughout various tissues was close to that of [14C]cholesterol being administrated under the same conditions. The analysis of radioactive products from blood serum showed that 40-60% of 3 beta-(2-hydroxy-2-[3H]ethoxy)- cholest-5-ene was converted to the acyl derivative under experimental conditions.

3 beta-(2-Hydroxyethoxy)-, 3 beta-(4'-hydroxybutoxy)-, 3 beta-(6-hydroxyhexyloxy)-, 3 beta-(9-hydroxynonyloxy)-, and 3 beta-(2-hydroxy-2-[3H]ethoxy)cholest-5-enes were synthesized. By means of a spin probe, the influence of the synthesized compounds on the phase transition of dimyristoylphosphatidylcholine were estimated. Time and dose dependences of the incorporation of 3 beta-(2-hydroxy-2-[3H]ethoxy)cholest-5-ene into rabbit hepatocytes (the primary culture) were studied. 3 beta-(2-Hydroxyethoxy)- and 3 beta-(4-hydroxybutoxy)cholest-5-enes were shown to inhibit cholesterol biosynthesis from [14C]acetate in rabbit hepatocyte cultures upon a 24-hour preincubation.

Peroxisomes are capable of beta-oxidizing a variety of substrates including the CoA esters of straight chain fatty acids, 2-methyl-branched fatty acids and the bile acid intermediates di- and trihydroxycoprostanic acids. The first reaction of peroxisomal beta-oxidation is catalyzed by an acyl-CoA oxidase. Rat liver peroxisomes contain three acyl-CoA oxidases: 1) palmitoyl-CoA oxidase, oxidizing straight chain acyl-CoAs; 2) pristanoyl-CoA oxidase, oxidizing 2-methyl-branched acyl-CoAs; and 3) trihydroxycoprostanoyl-CoA oxidase, oxidizing the CoA esters of the bile acid intermediates (Van Veldhoven, P.P., Vanhove, G., Asselberghs, S., Eyssen, H. J., and Mannaerts, G. P. (1992) J. Biol. Chem. 267, 20065-20074). We have now investigated whether the third step of peroxisomal beta-oxidation, catalyzed by a 3-hydroxyacyl-CoA dehydrogenase, is also catalyzed by multiple enzymes, using the 3-hydroxyacyl-CoA derivatives of palmitic acid, 2-methylpalmitic acid, and trihydroxycoprostanic acid as the substrates to monitor the dehydrogenase activities. In order to avoid contamination with mitochondrial 3-hydroxyacyl-CoA dehydrogenases, highly purified peroxisomes from untreated rats were employed as the enzyme source. Subfractionation of the peroxisomes revealed that the major portion of the dehydrogenase activities with all three substrates was present in the peripheral membrane protein fraction. Separation of this fraction on various chromatographic columns resulted in the purification of the well known multifunctional protein, a 78-kDa monomeric protein that displays 3-hydroxyacyl-CoA dehydrogenase plus hydratase activity, as well as of four additional novel dehydrogenases with different substrate specificities. Three of the enzymes are monomeric proteins of 35 kDa, 56 kDa, and 79 kDa, respectively. The latter enzyme also displays hydratase activity. The fourth enzyme is a dimer of 89 kDa, the subunits of which form a doublet at 40 kDa. The exact physiological role of each of the 3-hydroxyacyl-CoA dehydrogenases requires further investigation.

The NBT reduction test was used to assess the neutrophilic activities in 49 patients with bronchial asthma. 12 healthy donors were examined for control. The NBT test values were lower in health than in asthma: 8.8 +/- +0.97 vs. 12.8 +/- 0.7%, respectively, p0.05. Addition of a specific fungal allergen resulted in a twofold increase of the count of formasan-positive cells. A lower, but still a significant increase of the count of active granulocytes was induced in the asthmatics by home dust allergen (17.7 +/- 0.91%). The results of induced NBT test and of the reaction of antigen-specific injury of the granulocytes were in excellent correlation (r = 0.65, p0.05). There was no correlation of this test data with those of indirect Shelley's test or skin tests. This fact indicates the contribution of both the immediate and delayed mechanisms to the pathogenesis of fungal bronchial asthma.

Primary culture of rabbit hepatocytes was used for study the influence of hypolipidemic drug bezafibrate on bile acid production. Bezafibrate inhibits bile acid synthesis from endogenous and exogenous (lipoprotein) cholesterol at concentration range 1-10 micrograms/ml. Such inhibitory action of bezafibrate on bile acid synthesis should be kept in mind while applying hypolipidemic treatment.

A comparison of effects of two hypocholesterolemic drugs--mevinolin and glycyrrhizinic acid, on cholesterol and bile acid metabolism in cultured rabbit hepatocytes has been carried out. The following parameters have been determined: i) cholesterol synthesis from [2-14C]acetate; ii) bile acid production from newly synthesized and [4-14C]-labeled HDL2 cholesterol, and, iii) total cholesterol efflux into the incubation medium Mevinolin (0.5 microgram/ml) inhibited [2-14C] acetate incorporation into cholesterol by more than 90%. Conversely, glycyrrhizinic acid did not influence cholesterol synthesis even when used at high (100 micrograms/ml) concentrations but stimulated the conversion of endogenous (by 37%) and exogenous (by 18%) cholesterol into bile acids and increased, in addition, the proportion of bile acids in the total sterol pool released from hepatocytes into the incubation medium. At the same time, mevinolin used at 0.5 microgram/ml decreased the bile acid production by endogenous (by 27%) and exogenous (by 40%) cholesterol. The data obtained suggest that glycyrrhizinic acid exerts hypocholesterolemic action by stimulation of cholesterol conversion into bile acids without any effect on cholesterol synthesis. As for mevinolin, it has a cholesterol-suppressing effect via a mechanism of cholesterol synthesis inhibition only.

In our study the influence of oxidated cholesterol derivatives (7 alpha, 7 beta-oxicholesterol, 7-ketocholesterol, cholestene-3-one) on binding and degradation of beta-VLDL by human and rabbit hepatocytes was investigated. Cholesterol oxy derivatives inhibit the degradation of beta-VLDL in rabbit hepatocyte culture. There is no such effect with human hepatocytes. However beta-VLDL binding with human hepatocytes is significantly decreased under oxidated cholesterol derivatives influence.

Primary cultures of rabbit hepatocytes were used to investigate the effect of purified (B-100 free) chylomicron remnants (CR) on lipid and bile acid metabolism. ApoB-100-containing lipoproteins were removed from the CR-enriched plasma fraction by affinity column chromatography on Sepharose 4B conjugated with anti-apoB-100 monoclonal antibodies. CR were shown to stimulate the accumulation of neutral lipids in hepatocytes in a dose-response manner. After 24-hour preincubation of rabbit hepatocytes with 50 micrograms protein/ml CR the cellular neutral lipid content increased: 1.9-4-fold for triglycerides, 1.5-3.7-fold for free cholesterol and 1.5-2.5-fold for esterified cholesterol. This accumulation was accompanied by a decreasing incorporation of [14C] acetate into cholesterol (80-90%) and triglycerides (70-80%). At the same time the incorporation of [14]oleate into triglycerides increased by 50-65%. The inhibited biosynthesis of fatty acids might account for this effect. No effect of CR on cholesterol esterification by [14C]oleate was observed. CR increased the amount of triglycerides and free cholesterol secreted in very low density lipoproteins (VLDL). The secretion of taurocholic acid was decreased. These data confirm our hypothesis that dietary cholesterol is preferentially secreted by hepatocytes within VLDL but is not accumulated as cholesterol esters or oxidized to bile acids.

The effect of individual oxysterols--products of auto-oxidation of cholesterol on bile acid synthesis by cultivated rabbit hepatocytes was studied. Relative rates of bile acid synthesis were measured as the conversion of 4-14C cholesterol-HDL2 into total 4-14C labeled bile acids. 7 beta-hydroxycholesterol and 3,5-cholestane-7-dione strongly inhibited bile acid synthesis at concentrations 1-10 micrograms/ml. These data support the hypothesis that oxidized cholesterol derivatives accelerate the development of hypercholesterolemia in rabbits fed on cholesterol containing diet.

Using human and rabbit hepatocyte cultures, the effects of khellin and timefurone on lipoprotein metabolism were studied with special reference to the following parameters: i) binding and degradation of 125I-labeled low density lipoproteins (LDL); ii) apoprotein B (apo-B) secretion measured by immunoenzymatic assay, iii) [35S]methionine labeled apo-B and apo-E within the composition of very low density lipoproteins (VLDL); iiii) total cholesterol synthesis and cholesterol secretion within the composition of VLDL. The therapeutic concentrations (0.1-10 micrograms/ml) of the above drugs had no appreciable effect on the binding and degradation of 125I-LDL but inhibited the secretion of apo-B VLDL, leaving the apo-E VLDL unaffected. This was paralleled with inhibition of cholesterol synthesis (by 30-50%) and VLDL secretion. These results suggest that khellin and timefurone mediate the hypolipidemic effect via the reduction of the intracellular synthesis of cholesterol and secretion of apo-B containing VLDL by hepatocytes.

Basophil degranulation test (BDT) was used in examinations of patients suffering from allergies. A modified technique was employed with toluidine blue staining and basophil scintillation in a counter chamber. The examinees were divided into three groups. Group 1 (n = 34) consisted of patients suffering from atopic bronchial asthma with suspected sensitization to home dust. Group 2 included 118 patients with a history of allergy to penicillin. Group 3 consisted of 51 patients with drug allergies (streptomycin, vitamin B1, procaine, analgin intolerance). In all the cases specific diagnosis was confirmed by skin and provocation test. 71.4 percent of the patients with sensitization to home dust allergen showed positive results in BDT, as did 68.6 percent of Group 3 subjects. Of the cases with penicillin sensitization confirmed by application test 91.7 percent were positive in BDT, of those with positive intradermal tests, 66.7 percent were BDT-positive, this being probably explained by individual sensitivity of the patients. These results recommend BDT, an informative and simple technique, for wide practice.

The supernatant obtained after centrifugation of a suspension of viable lymph gland cells from immunized animals induced sensitivity to lysis in vitro by specific antigen in lymph gland cells from intact mice in vivo. After chromatography of the supernatant on Sephadex G-200, this property was localized in fraction 3 (molecular weight about 30,000). Deoxyribonuclease, trypsin, and deproteinization did not affect this fraction, but ribonuclease deprived it of its inducing properties.

The lymph node viable cells suspension of immunized mice was centrifugated. The supernatant was chromatographed in Sephadex G-200, and fractions were deproteinized. The deproteinized third fraction (Mol wt 30000) stimulated specifically the plaque-forming cells of intact mice immunized by SRBC. It restored the capacity to antibody production in the lethally irradiated intact mice protected by the syngeneic bone marrow. The activity of this fraction disappeared following treatment with RNA-ase, but not with DNA-ase or trypsin. The first and the second deproteinized fractions of the supernatant inhibited non-specifically the viable lymph node cells of the immunized animals in the intact mice immunized with SRBC.

Migration of leukocytes and macrophages from capillary tubes placed in a well containing medium was measured by counting the number of cells coming out into the medium. The method is highly sensitive and enables a small number of cells to be used with a large number (up to 600 or more) of capillary tubes. Sodium azide, phytohemagglutinin, and incubation at 4°C inhibited migration of the cells from the capillary tubes. Dead cells did not migrate from the tubes into the medium. Tuberculin and Bacillus Calmette-Guerin (BCG) vaccine inhibited migration of macrophages of guinea pigs immunized with BCG but not with staphylococcal allergen, and vice versa.

Blood leukocytes from 30 patients with allergy to tuberculin and bacterial antigens were treated with antithymus (ATS) or anti-immunoglobulin serum (AIGS), after which the leukocyte migration inhibition (LMI) test was carried out with these antigens. ATS abolished LMI by tuberculin and sometimes by bacterial antigens (staphylococcal, streptococcal, etc.). AIGS frequently abolished LMI caused by bacterial antigens but not by tuberculin. In other cases treatment with any serum abolished LMI by antigens or, conversely, it was abolished only by treatment with both antisera in turn. The type of lymphocytes (T or B) determining the reaction to the same antigen in the secondary immune response differed in different patients and also differed in the same patient for different antigens. Five types of interaction between lymphocytes and antigen in the LMI test were distinguished.

Specific antitumor sensitization in patients with gastric cancer was detected by the leukocyte migration inhibition test. After preincubation for 24 h at 4°C in serum-free medium, areactive leukocytes from patients with gastric cancer in stages III–IV reacquired the ability to react specifically to allogenic antigens of a tumor in the same location. Preincubation did not affect inhibition by cancer antigens of migration of leukocytes from patients with noncancerous diseases. The supernatants of preincubated leukocytes from cancer patients contained substances inhibiting migration of the indicator leukocytes.

A factor capable of lysing in vitro, in the presence of a specific antigen, the cells of the lymph nodes and the thymus of intact mice was revealed in the supernatant obtained after the centrifugation of a suspension of viable cells of the lymph nodes and the thymus of the immunized mice. It was found by immunochemical methods that this factor had a mol. wt. of about 30000 dalton and an electrophoretic mobility in polyacrylamide gel exceeding that of mouse blood serum albumin. Besides, it was revealed by the precipitation reaction in agar that it was not an immunoglobulin or its chains.

To evaluate the impact of oxidized derivatives of cholesterol on the development of hypercholesterolemia in rabbits, the secretion of very low density lipoprotein (VLDL) apoproteins and lipids was studied in cultures of hepatocytes obtained from: i) control rabbits, ii) rabbits fed on purified cholesterol (PCH), and, iii) rabbits fed on old commercial cholesterol (OCH) containing 5% of oxidized cholesterol derivatives. The rabbits fed on OCH for 6 weeks revealed a 5-fold increase in the serum cholesterol level compared with that in PCH-fed rabbits. The secretion of VLDL apoproteins and lipids by hepatocytes of two cholesterol-fed groups was similar, but was 2-3 times as high as that of cells from control rabbits. The cholesterol ester content in hepatocytes and the secretion of VLDL cholesterol esters by hepatocytes from OCH-fed rabbits was dramatically increased in comparison with hepatocytes from control and PCH-fed rabbits. These effects appear to be caused by the activation of cholesterol esterification by oxidized cholesterol derivatives. The rapid development of hypercholesterolemia in OCH-fed rabbits is at least partly associated with the stimulation of hepatic VLDL production.

An examination of 79 children has shown that in acute hematogenic osteomyelitis lower parameters of non-specific resistance and immunity are of prognostic value. The administration of Pentoxyl and Levimizol improves the state of immunity and exerts a positive clinical effect.

Under study was the effect of various bacterial allergens on the migration of blood leucocytes from capillaries in vitro in 23 patients with acute appendicitis and in 18 healthy individuals. Bacterial allergens wound suppress leucocytes migration in all patients. Most frequently, sensibilization to allergens of hemolytic staphylococcus and hemolytic streptococcus was found. In 4 healthy persons this methods indicated sensibilization to some allergens. The interaction of activity sensibilized lymphocytes and passively sensibilized polynuclears of the appendix with bacterial antigens is assumed to tigger the hyperergic reaction in acute appendicitis.

Staphylococcal toxin at a concentration of 10(-3) inhibits in vitro the rosette-formation of lymphocytes, taken from healthy donors and patients with purulent septic diseases, with sheep and mouse red blood cells, changes the ratio of lymphocyte subpopulation, modifies the spontaneous antigen- and mitogen-dependent migration of leukocytes. The latter phenomenon is not linked with disturbances in the lymphokine-producing activity of lymphocytes, but results from changes in the migration properties of granulocytes.

The effect of tumor antigens and those of gastric mucosa on rosette-formation by T-lymphocytes of blood and sheep red blood cells was studied in 65 gastric cancer patients by means of a spontaneous E-rosette-formation variation test. Antigens of original tumor extracts stimulated rosette-formation in 55.4% of patients, more frequently in cases of stage I-II tumors than in those of stage IV. After antigens of normal mucosa were removed from tumor extracts the frequency of positive tests did not change significantly in gastric cancer group, whereas, in controls, it dropped from 26.4 to 7.5%. Tumor antigens tested did not produce the same effect on the rosette-formation by B-lymphocytes with mouse red blood cells.

The application of Dimexid and Dekaris is shown to give better results in the treatment of patients with chronic osteomyelitis.

The rate of synthesis and secretion of lipid and apoprotein components of lipoprotein fractions and of proteins of the nonlipoprotein fraction d greater than 1.21 g/ml by human hepatocytes in culture was determined. The cells were incubated for 18 hours in the media containing [14C] acetate or [3H]-marked leucine in the presence of bezafibrate or without it. VLDL, HDL and d greater than 1.21 g/ml fractions were separated by differential ultracentrifugation. The lipids were divided using thin-layer chromatography, and the apoprotein-using SDS-electrophoresis in polyacrylamide gel. Bezafibrate in the therapeutic concentration of 10 microM specifically inhibits apoprotein and VLDL lipid secretion. Lowered secretion of all VLDL apoproteins was revealed, which points to a decrease in the number of secreted particles. The effect of bezafibrate was found to be associated with the inhibition of the intracellular synthesis of lipids. The secretion of HDL proteins and of d greater than 1.21 g/ml fraction proteins was unchanged with 10 microM of bezafibrate.