[Stability of biocatalysts on the basis of carrageenan-immobilized Escherichia coli during continuous synthesis of L-malic acid]. / Stabil'nost' biokatalizatorov na osnove immobilizovannykh v karraginan kletok Escherichia coli v protsesse nepreryvnogo sinteza L-iablochnoi kisloty.

Continuous enzymatic synthesis of L-malic acid from potassium fumarate in packed-bed flow reactors was investigated. Carrageenan-immobilized Escherichia coli cells were used as a biocatalyst. The operational stability of the biocatalyst fumarase activity was studied, and conditions for preserving high activity of the biocatalyst were determined.

[Experience in the surgical treatment of chronic suppurative lung disease in children]. / Opyt khirurgicheskogo lecheniia khronicheskikh nagnoitel'nykh zabolevanii legkikh u detei.

UNLABELLED: Operations were performed on 750 children with cystic hypoplasia and dysontogenetic and acquired bronchiectases. The operation volume: pulmonectomy, lobectomy, combined resections, resection of pulmonary tissue with extirpation of bronchi, extirpation of bronchi. COMPLICATIONS: atelectasis, pneumonia, intrapleural hemorrhage were encountered in 87 (11.6%) children. Six (0.8%) children died. Recurrent or residual bronchiectases were found in 27 children, 18 underwent a second operation. Recurrences were encountered mainly in children with dysontogenetic bronchiectases.

[The effect of composition and ionic strength of external solution on the aspartate-ammonia lyase and fumarate hydratase activity in Escherichia coli cells]. / Vliianie sostava i ionnoi sily vneshnego rastvora na aktivnost' aspartat-ammiak-liazy i fumarat-gidratazy v kletkakh Esherichia coli.

It was found that the nonspecific effect of ionic strength of the external solution on the enzymatic activity of E. coli cells consists in rapid changes in the permeability of cell membranes interacting with the substrate. This effect depends on the initial substrate concentration, i.e., ionic strength of the external solution, and is maintained for some time as the substrate concentration decreases. Chloramphenicol, a protein synthesis inhibitor, and sodium azide, a respiration inhibitor (300 micrograms/ml and 200 microM, respectively) do not change the enzymatic activity of E. coli cells during the synthesis of L-aspartic and L-malic acids from fumaric acid. The kinetic equations of L-aspartate and L-malate synthesis are described by equations of zero and intermediate (between zero and first) order, respectively.

[Determination of 3,4-dioxyphenyl-L-alanine by spectrophotometric and chromatographic methods in enzymatic synthesis using microbial cells]. / Opredelenie 3,4-dioksifenil-L-alanina spektrofotometricheskim i khromatograficheskim metodami v fermentativnom sinteze s pomoshch'iu kletok mikroorganizmov.

A possibility of using the ninhydrin reaction for 3,4-dihydroxyphenyl-L-alanine (DOPA) determining during the synthesis from pyrocatechol and ammonium pyruvate was verified by using free and immobilized cells of Citrobacter freundii, st. 62. Spectrophotometric assay was performed at the adsorption maximum for the DOPA-ninhydrin complex at 390 nm. DOPA can be reliably quantified in the presence of all components at 20-fold and greater dilution of the reaction mixture. A high-sensitive quantitative assay of the reaction mixture was developed based on phase-reversed HPLC. A quantitative correlation was observed between spectrophotometric and chromatographic assays. The assays were employed to study in detail the initial period and equilibrium of DOPA synthesis and its characteristic features, which made it possible to construct a kinetic model of the process.

[Isolation of spheroplasts from Escherichia coli 85 for aspartate-ammonia-lyase localization]. / Poluchenie sferoplastov iz Escherichia coli 85 dlia opredeleniia lokalizatsii spartat-ammiak-liazy.

Conditions were determined for preparation of spheroplasts from E. coli under the action of lysozyme in the presence of EDTA. The preparation took from 10 to 15 min. The degree of conversion to spheroplasts was monitored spectrophotometrically at 660 nm. The spheroplasts formed were unstable in Tris-HCl buffer and immediately lysed, but they were more stable in 1 M sucrose. At lysozyme concentrations above 40 micrograms/ml of the reaction mixture, the cells lysed to a greater extent. The distribution of aspartate ammonia-lyase activity between the precipitate of the spheroplasts and the supernatant allowed the authors to suggest that aspartase should be located in the cytoplasm.

[Enzymatic synthesis of L-malic acid from fumaric acid using immobilized Escherichia coli cells]. / Enzimaticheskii sintez L-iablochnoi kisloty iz fumarovoi s pomoshch'iu immobilizovannykh kletok Escherichia coli.

Optimal conditions were chosen for cultivation of Escherichia coli 85 cells with a rather high fumarate-hydratase activity on a cheap medium containing no edible raw material. An active biocatalyst for the synthesis of L-malic acid from fumaric acid was obtained based on E. coli 85 cells immobilized in carrageenan. The enzymatic synthesis of L-malic acid from potassium fumarate was kinetically studied and optimized. Some thermodynamic parameters of fumaric acid hydration into malic acid were determined. A technique for assaying the reaction mixture was developed that involved high performance liquid chromatography.

[Kinetic study of 3,4-dihydroxyphenyl-L-alanine synthesis in Citrobacter freundii cells immobilized in carrageenan]. / Kineticheskoe izuchenie sinteza 3,4-dioksifenil-L-alanina kletkami Citrobacter freundii, immobilizovannymi v karraginan.

A kinetic study was carried out of the enzymatic synthesis of 3,4-dihydroxyphenyl-L-alanine (DOPA) by the Citrobacter freundii 62 cells, possessing tyrosine-phenol-lyase (TPL) activity, immobilized in carrageenan, and optimum conditions of the reaction were found. The dependence of the TPL activity and its stability on the conditions of the DOPA synthesis was investigated. The TPL activity was higher and more stable in the immobilized cells as compared to free ones.

[Aspartase activity of Escherichia coli, strain 85, cells grown on glucose-mineral medium with yeast extract]. / Aspartaznaia aktivnost' kletok Escherichia coli, shtamm 85, vyrashchennykh na gliukozomineral'noi srede s drozhzhevym ékstraktom

The conditions for cultivation of E. coli 85 on a glucose-mineral medium with a yeast extract were optimized. The cells obtained had a high aspartate ammonia-lyase activity. The aspartase activity was determined kinetically both by consumption of the substrate, ammonium fumarate, and by accumulation of the product, aspartic acid.

[Aspartase activity and the stability of Escherichia coli cells immobilized in different carrageenan samples]. / Aspartaznaia aktivnost' i stabil'nost' kletok Escherichia coli, immobilizovannykh v razlichnye obraztsy karraginana.

The cells of Escherichia coli 85 immobilized in carrageenan from various sources were being studied for the aspartase activity and stability. These properties of the resultant preparations which display a relatively high and stable biocatalytic activity were shown to be almost independent of the raw material from which carrageenan was obtained and of the degree of its purification.

[Comparison of the aspartase activity and its stability in Escherichia coli cells immobilized on polyacrylamide gel and carrageenan]. / Sravnenie aspartaznoi aktivinosti i ee stabil'nosti u kletok Escherichia coli, immobilizovannykh v poliakrilamidnyi gel' i karraginan.

The conditions for immobilization of Escherichia coli cells (Soviet strain 85) on the natural polysaccharide carrier carrageenan (Soviet-made) were investigated and kinetic regularities of the aspartase reaction catalysed by immobilized in carrageenan cells of E. coli 85 were established. The conditions for retaining a high aspartase activity and stability of biocatalysts based on the E. coli 85 cells immobilized in PAAG and carrageenan were determined using full-loaded tanks for continuous synthesis of L-aspartic acid. The time-stable aspartase activity of the biocatalyst can be increased by treating the beads of the catalyst with bifunctional reagents (hexamethylenediamine, glutaraldehyde), the most active catalyst for the biotechnological synthesis of L-aspartic acid being obtained when carrageenan is used.

[Enzymatic synthesis of 3,4-dihydroxyphenyl-L-alanine by free and immobilized Citrobacter freundii cells]. / Fermentativnyi sintez 3,4-dioksifenil-L-alanina svobodnymi i immobilizovannymi kletkami Citrobacter freundii.

The Citrobacter freundii 62 cells immobilized in PAAG and possessing the tyrosine-phenol-lyase (TPL) activity catalyse the synthesis of 3,4-dihydroxyphenyl-L-alanine (DOPA) from pyrocatechol and ammonium pyruvate. The synthesis of DOPA was studied using both free and immobilized bacterial cells. When the concentration of pyrocatechol is over 0.1 M the TPL activity of the cells is inhibited. The concentration of pyrocatechol can be increased up to 0.3 M by using an equimolar mixture of pyrocatechol and boric acid. The addition of ascorbic acid as an antioxidant results in a lower TPL activity of both free and immobilized bacterial cells.

[Study methods for localizing enzymes in the cells of gram-negative bacteria (a review)]. / Metody issledovaniia lokalizatsii fermentov v kletkakh gramotritsatel'nykh bakterii (obzor).

The present review systematizes the literature data on localization of enzymes in cells of Gram-negative bacteria. It centres round the methods used for studying the enzyme localization. The criteria according to which one can locate an enzyme in bacterial cells are discussed.

[Fumarate hydratase activity of various Escherichia coli strains]. / Fumarat-gidrataznaia aktivnost' razlichnykh shtammov Escherichia coli.

The fumarate hydratase activity of intact cells was determined for 36 strains of Escherichia coli, receiver from the All-Union Collection of Microorganisms, to reveal a producer of L-malic acid. A research was made to find optimal media for cultivating microorganisms possessing the fumarate hydratase activity. Spectrophotometric and chromatographic methods were chosen to detect malic acid in the complete reaction mixture, which are available for kinetic study of the malic acid synthesis from potassium fumarate.

[Late development of tumors in the liver of dogs after long-term external gamma-radiation]. / Razvitie opukholei v pecheni sobak v otdalennye sroki posle dlitel'nogo vneshnego gamma-oblucheniia.

Development of tumors in the liver of dogs exposed to gamma-quanta for 3 and 6 years at dose--rates of 0.0006, 0.0017 and 0.0034 Gy/day was studied 1-10 years after termination of the exposure. The results are summarized in this work. Tumors were found in 27 out of 89 dogs. The number of benign and malignant tumors was virtually the same (13 and 14). In the first place were hepatoma, among benign neoplasms (9 out of 13), and liver cancer, among malignant tumors (12 out of 14). Neoplasms were more frequent (32%) in exposed animals than in the controls (19%). Tumors were almost two times more frequent and developed earlier after 6 year- than after-3-year-irradiation.

[Immobilization of Citrobacter freundii cells with tyrosine phenol-lyase activity by entrapment in natural gels]. / Immobilizatsiia kletok Citrobacter freundii s tiroz-infenol-liaznoi aktivnost'iu metodom vkliucheniia v prirodnye geli.

A comparative study on immobilization of Citrobacter freundii cells by entrapment in carrageenan, agar, agar-agar, and gelatin gels (5, 10, and 15%) was carried out. Gelatin gels were treated with glutaraldehyde to make them more rigid. As a result, the tyrosine phenol-lyase activity of these samples was less than that of free cells (about 40%). The yield of TP-lyase activity was 40--60% when cells were immobilized in 5% and 7% agar and agar-agar gels. The cells entrapped in carrageenan gels, the concentration of which was varied from 2 to 10%, possessed the highest tyrosine phenol-lyase activity (up to 90%). The efficiency of cell entrapment was high for all the carrier and equal to 70--90%. The plastic strength and swelling of the above gels, as well as the phenol adsorption on the carriers and the release of the bacterial cells from them were studied under the conditions of tyrosine phenol-lyase reaction.

[Hemodynamics of the lesser circulation in prolonged hypokinesia (based on data from a morphological study)]. / K voprosu o sostoianii gemodinamiki malogo kruga krovoobrashcheniia pri dlitel'noi gipokinezii (po dannym morfologicheskogo issledovaniia).

This paper presents data on pulmonary circulation of rats during prolonged hypokinesia (30 to 165 days). It was found that the hypokinetic exposure of 30 to 60 days produced venous and, in particular, capillary plethora associated with blood redistribution and pooling in the lungs. As the exposure continued, the plethora level decreased due to the development of compensatory-adaptive reactions in the lung vessels. For instance, on hypokinetic day 90 small arteries of the muscle type developed a spasm which accelerated circulation stabilization. By hypokinetic days 120-165 pulmonary circulation returned to normal due to the further development of compensatory-adaptive mechanisms in lung vessels (tendency for hypertrophy of the media of small arteries and increase of its cross-sectional area).

[Stability of the biocatalysts of L-aspartic acid synthesis based on immobilized Escherichia coli cells]. / Stabil'nost' biokatalizatorov sinteza L-asparaginovoi kisloty na osnove immobilizovannykh kletok Escherichia coli.

Experiments were carried out to investigate the process of a continuous enzymatic synthesis of L-aspartic acid from ammonium fumarate in uniform filling flow reactors. Escherichia coli (Soviet strain 85) cells immobilized in polyacrylamide gel granules reinforced by a solid carrier were used as biocatalysts. The conditions, under which a high aspartase activity of the biocatalyst and a stable hydrodynamic performance of the reactor were maintained, were determined. The main kinetic characteristics of a continuous performance of the reactor for 150 days were obtained.