Biocompatible Silica-Polyethylene Glycol-Based Composites for Immobilization of Microbial Cells by Sol-Gel Synthesis.

Biocatalysts based on the methylotrophic yeast VKM Y-2559 immobilized in polymer-based nanocomposites for the treatment of methanol-containing wastewater were developed. The organosilica composites with different matrix-to-filler ratios derived from TEOS/MTES in the presence of PEG (SP-composite) and from silicon-polyethylene glycol (STP-composite) differ in the structure of the silicate phase and its distribution in the composite matrix. Methods of fluorescent and scanning microscopy first confirmed the formation of an organosilica shell around living yeast cells during sol-gel bio-STP-composite synthesis.

Impact of hydrophilic polymers in organosilica matrices on structure, stability, and biocatalytic activity of immobilized methylotrophic yeast used as biofilter bed.

The impact of hydrophilic polymers in an organosilica matrix on the features and performance of immobilized methylotrophic yeast cells used as biocatalysts was investigated and described. Yeast cells were immobilized in a matrix made of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) by one-step sol-gel route of synthesis in the presence of polyethylene glycol (PEG) or polyvinyl alcohol (PVA). Organosilica shells were spontaneously built around cells as a result of yeast immobilization at a TEOS to MTES ratio of 85/15 vol% and hydrophilic polymer (PEG or PVA).

A kinetic approach to the formation of two-mediator systems for developing microbial biosensors as exemplified by a rapid biochemical oxygen demand assay.

This work proposes a method of forming a microorganism-mediator(s) receptor system, in which the rates of separate stages of mediator bioelectrocatalysis are used as the basis for the development of biosensors for the biochemical oxygen demand (BOD) rapid assay. In the presence of a ferrocene mediator, the yeast was shown to enable oxidation of a larger range of substrates as compared with other investigated microorganisms-bacteria and yeast The rate constants of the interaction of the yeast with nine compounds, electron transfer mediators, were determined; the best mediator for these microorganisms was found to be neutral red (  = 0.681 ± 0.

Use of biocompatible redox-active polymers based on carbon nanotubes and modified organic matrices for development of a highly sensitive BOD biosensor.

This work investigated the use of redox-active polymers based on bovine serum albumin and chitosan, covalently bound to mediators neutral red and ferrocene and containing carbon nanotubes, for immobilization of Paracoccus yeei VKM B-3302 bacteria. The structures of produced polymers were studied by IR spectroscopy and scanning electron microscopy. Cyclic voltammetry and impedance spectroscopy found the electrochemical characteristics of the investigated systems: the heterogeneous electron transfer rate constant, the constant of the rate of interaction with P.

Registration of BOD using bacteria isolated from activated sludge.

This work investigated the properties of VKM B-3302 bacteria isolated from activated sludge and immobilized in an N-vinylpyrrolidone-modified poly(vinyl alcohol) matrix. The developed hydrogel formed a network structure to enable the entrapment of microbial cells with their viability and biocatalytic properties preserved, which ensured the technological possibility of replicating expendable biosensor receptor elements. A new ratio of the components for the synthesis selected in this work enabled producing a copolymer of an earlier undescribed chemical structure, which can be efficiently used for immobilization of highly sensitive bacteria.

Three-Dimensional Organization of Self-Encapsulating Bacterial Cells.

Self-organized bacteria have been the subject of interest for a number of applications, including the construction of microbial fuel cells. In this paper, we describe the formation of a self-organized, three-dimensional network that is constructed using B-1280 cells in a hydrogel consisting of poly(vinyl alcohol) (PVA) with -vinyl pyrrolidone (VP) as a cross-linker, in which the bacterial cells are organized in a particular side-by-side alignment. We demonstrated that nonmotile cells are able to reorganize themselves, transforming and utilizing PVA-VP polymeric networks through the molecular interactions of bacterial extracellular polysaccharide (EPS) components such as acetan, cellulose, dextran, and levan.

[Competition between redox mediator and oxygen in the microbial fuel cell].

The maximal rates and effective constants of 2,6-dichlorphenolindophenol and oxygen reduction by bacterim Gluconobacter oxydans in bacterial fuel cells under different conditions were evaluated. In an open-circuit mode, the rate of 2,6-dichlorphenolindophenol reduction coupled with ethanol oxidation under oxygen and nirogen atmospheres were 1.0 and 1.

Silica sol-gel encapsulated methylotrophic yeast as filling of biofilters for the removal of methanol from industrial wastewater.

This research suggests the use of new hybrid biomaterials based on methylotrophic yeast cells covered by an alkyl-modified silica shell as biocatalysts. The hybrid biomaterials are produced by sol-gel chemistry from silane precursors. The shell protects microbial cells from harmful effects of acidic environment.

[Bioanode for a microbial fuel cell based on Gluconobacter oxydans inummobilized into a polymer matrix].

Acetic acid bacteria Gluconobacter oxydans subsp. industrius RKM V-1280 were immobilized into a synthetic matrix based on polyvinyl alcohol modified with N-vinylpyrrolidone and used as biocatalysts for the development ofbioanodes for microbial fuel cells. The immobilization method did not significantly affect bacterial substrate specificity.

Yeast-based self-organized hybrid bio-silica sol-gels for the design of biosensors.

The methylotrophic Pichia angusta VKM Y-2559 and the oleaginous Cryptococcus curvatus VKM Y-3288 yeast cells were immobilized in a bimodal silica-organic sol-gel matrix comprised of tetraethoxysilane (TEOS), the hydrophobic additive methyltriethoxysilane (MTES) and the porogen polyethylene glycol (PEG). Under carefully optimized experimental conditions, employing basic catalysts, yeast cells have become the nucleation centers for a silica-organic capsule assembled around the cells. The dynamic process involved in the formation of the sol-gel matrix has been investigated using optical and scanning electron microscopic techniques.

BOD biosensor based on the yeast Debaryomyces hansenii immobilized in poly(vinyl alcohol) modified by N-vinylpyrrolidone.

An amperometric biosensor for assessing the biochemical oxygen demand (BOD) was formed by immobilizing Debaryomyces hansenii VKM Y-2482 yeast cells in poly(vinyl alcohol) modified by N-vinylpyrrolidone. Modification provided for a high sensitivity and stability of the bioreceptor. A high oxidative activity of the receptor element and the absence of any toxic effect of assayed compounds were shown for 34 substrates (alcohols, carbohydrates, carboxylic acids, amino acids, nitrophenols and surfactants) that may occur in wastewaters.

[Stereotypes of adaptive adjustment of the organism and their manifestations in the structure of morbidity in population and professional groups].

The results of theoretical analysis and generalizations of long-term works of the author on the physiological-hygienic and clinical studies of the body in the adult population, exposed to influence of extremely pronounced environmental factors and conditions of employment are reported. The result of generalization - the theory of adaptive adjustment of the organism in extreme conditions - is presented as a system of postulates. The features of disease as a manifestations of the phenomenon of the side effects of adaptive adjustment of the organism are considered.

[Receptor elements for biosensors in two ways of methylotrophic yeast immobilization].

Receptor elements for biosensors based on Hansenula polymorpha NCYC 495 In yeast cells for ethanol assay were developed using two ways of cell immobilization, i.e., physical adsorption on a glass fiber membrane and covalent binding on a modified nitrocellulose membrane.

[Microbial biosensors for detection of biological oxygen demand (a review)].

The review briefs recent advances in application of biosensors for determining biological oxygen demand (BOD) in water. Special attention is focused on the principles of operation of microbial BOD sensors; the information about biorecognition elements in such systems and the methods used for immobilization of biological components in film biosensors is summarized. Characteristics of some BOD sensor models are considered in detail.

[Use of blue-green algae for biogas production].

Perspectives for nature protection and energy-saving, by using blue-green algae, are discussed. Utilization of their phyto biomass for biogas manufacture will lead to the environmental normalization of the Transdniestria and allow one to have about 19,000,000 m3 of methane only from the water area of only one Kremenchug water basin each vegetative period (70 days).

[The dorsal hippocampus injury influences chronobiological effects of depressants and antidepressants in rats].

The administration of depressant reserpine and antidepressant imipramine in rats is manifested by opposite trends in the chronobiological aspect of behavior. Reserpine disorganizes the circadian locomotion rhythm and increases the rhythmological index of depression in the forced swim test. In contrast, imipramine increases the circadian rhythm contrast and decreases the index of depression.

[Standard and hyperfractionated irradiation for locally advanced tumors (T3NOMO) of the larynx].

Two modalities of radiotherapy of locally advanced tumors (T3N0M0) of the larynx were compared in the treatment of 89 patients. Forty-six patients of group I received 2 Gy daily, 5 times a week (COD 65-70 Gy), while 43 patients of group 11--1.1 Gy of multifractionated radiation twice a day, at 4-hr interval (COD 70-75 Gy).

[Choice of the optimal variant of plastic surgery in head and neck tumors].

Indications for planning primary and delayed operations for head and neck tumors have been evolved on the basis of our 15-year experience with 667 reconstructive surgeries (550 patients) 425 of which (77%) were conducted in one stage.

[Primary and delayed combined plastic repair of pharngoesophagostomies in patients with laryngopharyngeal cancer].

Primary and delayed combined plastic surgery using massive musculocutaneous pedicle flaps composed of musculus pectoralis major, musculus sternocleidomastoideus, musculus trapezius in combination with cellulocutaneous and skin flaps provides appropriate plastic repair of total and subtotal defects of the pharynx and cervical esophagus after combined interventions for oropharyngeal cancer stage III-IV. Composite flaps warrant good and satisfactory functional and cosmetic outcomes in the majority of patients without additional hospital stay.

[Morphological and biological features of squamous cell carcinoma of the larynx].

The study of morphological and biological criteria of laryngeal squamous cell carcinoma in 81 patients proved essential in the disease prognosis. In grade I malignancy 90 +/- 6.7% of patients were 3 years free of recurrences and metastases, in grade 11 - 76 +/- 8.

[DNA ploidy of tumor cells in prognostication of the course of malignant neoformations].

DNA flow cytometry (FCM) was used for the clinical prognosis in patients undergone surgical removal of a tumor. The relationship between the structure of the tumor cell population (ploidy) and the frequency, time of a relapse onset (recurrence, metastasis), and the survival length were analyzed. All the patients had presurgical treatment (chemo- and/or radiotherapy).

[Reconstructive surgery and organ-sparing methods in the treatment of patients with laryngeal and oral cavity tumors].

Some advances have been recently made to improve survival rates among patients with common advanced larynx and oropharyngeal cancer. In this connection, it is essential to improve the quality of such patients' life. A total 382 patients with Degrees III-IV laryngeal and oral cancers were followed up.

[Laryngeal reconstruction after extensive frontolateral resections in locally disseminated laryngeal cancer].

In the department of upper respiratory and gastrointestinal tract tumors of the Russian Cancer Research Center one-stage laryngeal reconstruction after extensive frontal-lateral resection for cancer stage III (T3N0M0) was performed in 11 patients. Two variants of the reconstruction were used: plastic reconstruction of the laryngeal defect with a dermal-muscle graft involving m. sternohyoideus and with down retraction of the epiglottis.

[Statistics and prehospital diagnosis of malignant neoplasms of upper respiratory tract in Russia].

In 1990 in Russia there were 12,264 newly diagnosed cases of upper respiratory tract cancer and 7562 relevant lethal cases. The authors provide data on such cancer incidence rate by site, groups of population, sex, age, type of tumor. Standardized incidence and mortality rates for various regions of Russia are indicative of the trend to the rates increase and relevant economic losses.