Effect of Sodium Lauryl Sulfate on Sorption of Cells of the Electrogenic Bacterium Strain Micrococcus luteus on Carbon Cloth.

Results of a study into the effect of anionic surfactant sodium lauryl sulfate on the sorption of cells of the electrogenic bacteria strain Micrococcus luteus 1-I on the surface of carbon cloth used as electrodes in microbial fuel cell (MFC) technology are presented. Investigations using spectrophotometry, microscopy and microbiology revealed an increase in the degree of sorption of microbial cells on carbon cloth under the action of sodium lauryl sulfate at concentrations of 10 and 100 mg/l. The sorption of cells did not significantly differ from the control at a surfactant content of 200, 400 and 800 mg/l. It had no negative effect on bacterial growth in the concentration range from 10 to 800 mg/l. Due to the fairly high resistance of the electrogenic strain M. luteus 1-I to sodium lauryl sulfate, a widespread component of wastewater, it may be considered as a prospective bioagent for the treatment of domestic wastewater using MFC technology.

Electrochemical Characteristics of the Oxidation of Sulfur- and Iron-Containing Compounds by Acidophilic Microorganisms.

The electrochemical features of the interactions of sulfur- and iron-containing compounds (ferrous sulfate, elemental sulfur, pyrite tailings, cysteine, sodium thiosulfate) with a model acidophilic consortium, including the genera Leptospirillum, Sulfobacillus, Acidithiobacillus, Ferroplasma, and Acidiplasma, were studied. The method of cyclic voltammetry recorded redox processes at the electrode/solution interface in the presence of the studied sulfur- and iron-containing compounds. In general, the modeling consortium led to the intensification of these processes. The characteristics of the diffuse layer near the electrode/solution interface were studied using electrochemical impedance spectroscopy. The introduction of microorganisms and/or substrates into the supporting electrolyte led to a decrease in the slope and can be interpreted as evidence of their effect on the diffusion part of the double layer. Its contribution decreases in favor of ion transport. All this, in general, does not contradict the assumption of cell adsorption on the electrode surface. Confocal laser scanning microscopy confirmed this assumption and showed cell adhesion to the surface. The data obtained confirm the importance of bioelectrochemical processes of the studied group of microorganisms in biotechnological processes associated with the leaching of metals from sulfide ores.

Antioxidant activity of humic substances via bioluminescent monitoring in vitro.

This work considers antioxidant properties of natural detoxifying agents-humic substances (HS) in solutions of model inorganic and organic compounds of oxidative nature-complex salt K3[Fe(СN)6] and 1,4-benzoquinone. Bioluminescent system of coupled enzymatic reactions catalyzed by NAD(P)H: FMN-oxidoreductase and bacterial luciferase was used as a bioassay in vitro to monitor toxicity of the oxidizer solutions. Toxicities of general and oxidative types were evaluated using bioluminescent kinetic parameters-bioluminescence intensity and induction period, respectively. Antioxidant activity of HS was attributed to their ability to decrease both general and oxidative toxicities; the HS antioxidant efficiency was characterized with detoxification coefficients D GT and D OxT, respectively. Dependencies of D GT and D OxT on HS concentration and time of preliminary incubation of the oxidizers with HS were demonstrated. The optimal conditions for detoxification of the oxidizers were >20-min incubation time and 0.5 × 10(-4) to 2 × 10(-4) M of HS concentration. The present study promotes application of the enzymatic luminescent bioassay to monitor toxicity of pollutants of oxidative nature in environmental and waste waters in remediation procedures.

Bioluminescence as a tool for studying detoxification processes in metal salt solutions involving humic substances.

The paper considers effects of humic substances (HS), as natural attenuators of toxicity, on solutions of model inorganic pollutants, metal salts - Pb(NO(3))(2), СоСl(2), CuSO(4), Eu(NO(3))(3), СrСl(3), and K(3)[Fe(СN)(6)]. Luminous bacteria Photobacterium phosphoreum and bioluminescent system of coupled enzymatic reactions were used as bioassays to monitor toxicity of salt solutions. The ability of HS to decrease or increase toxicity was demonstrated. Detoxifying concentrations of HS were determined; detoxification coefficients were calculated at different times of exposure of salt solutions to HS. To study the combined effects of HS and salts on bioluminescent assay systems, the rates of biochemical reactions and bacterial ultrastructure were analyzed. The detoxifying effects were explained by: (1) decrease of free metal content in water solutions under metal-HS binding; (2) increase of biochemical reaction rates in a bioluminescent assay system under HS effect; (3) enhancement of mucous layers on cell surface as a response to unfavorable impact of toxicants. Detoxifying mechanisms (2) and (3) reveal the active role of bioassay systems in detoxification processes.

Bioluminescence assays: effects of quinones and phenols.

The influence of a series of quinones and phenols on bacteria bioluminescence systems was investigated. Three bioluminescence systems used in ecological monitoring were compared: (1) water-soluble; (2) immobilized in starch gel coupled enzyme systems: NADH:FMN-oxidoreductase-luciferase; (3) luminescent bacteria. Bioluminescence inhibition constants of quinones and phenols and bioluminescence induction periods were compared. These kinetic parameters are proportional to quinone concentrations and depend on the quinone redox potential. Different effects of the substances are related to structure and properties of the bioluminescence systems. The set of bioluminescence assays for quinones and phenols monitoring should include two bioluminescence systems: 1 (or 2) and 3.

[Effect of quinones on enzymatic bioluminescence of NADH-dependent systems]. / Deistvie khinonov na fermentativnye bioliuminestsentnye NADH-zavisimyesistemy.

The effects of a number of quinones on the bioluminescence characteristics of a three-component enzymatic system containing alcohol dehydrogenase, bacterial luciferase, and NADH-FMN oxidoreductase were studied to find the most sensitive kinetic parameters of the system intended to be used in biological testing. Both direct and back reactions catalyzed by alcohol dehydrogenase were studied in the presence and in the absence of quinones. The kinetic parameters of the bioluminescent system were found to depend on the redox potentials and concentrations of quinones. The quinone-induced effects were shown to be associated with changes in the NAD+/NADH ratio in the chain of NADH-dependent enzymes. The three-enzyme system based on alcohol dehydrogenase is suggested as a bioluminescence test for ecological monitoring of waste water.

Bringing impacted mandibular second premolars into occlusion.

Impaction of the mandibular second premolars is relatively rare and may offer general dentists and orthodontists special challenges during treatment. The authors discuss two cases involving impacted mandibular second premolars that had migrated before eruption. Surgical and orthodontic therapies were used to bring the teeth into occlusion. The authors emphasize early diagnosis and a collaborative approach between the dental professionals involved in treating these affected patients.

Bioluminescent method in studying the complex effect of sewage components.

The inhibition of bacterial luminescence has been used in testing industrial enterprises sewage. The toxicity of the sewage is less than the total toxicity of separate components due to neutralization of quinone products of polyphenol oxidation in the reactions with the other phenol components of sewage. Toxicity increase is due to their influence on the cell membrane. Studies of cell ultrastructure confirm this fact. The studied mechanism of the complex effect allowed a more accurate forecast of the ecological situation during the discharge of phenol compounds and metals. It also showed the necessity of taking into account the complex effect of sewage components on contaminant discharge into water reservoirs.

Maxillary canine-lateral incisor transposition--orthodontic management.

A case of maxillary canine-lateral incisor complete transposition is presented. Treatment options for transposed teeth, including alignment in their transposed positions, extraction of one or both transposed teeth, and orthodontic alignment to their normal positions in the arch, are discussed. The orthodontic technique and sequence used in this challenging case to align the fully transposed teeth to their normal position in the dental arch are described.

[Bioluminescent method of assessing the toxicity of colored substances in waste waters from celluose sulfate manufacture]. / Bioliuminestsentnyi metod otsenki toksichnosti okrashennykh veshchestv stochnykh vod sul'fattselliuloznogo proizvodstva.

The aim of this work was to study the applicability of a bioluminescent technique for assaying the toxicity of solutions containing lignin sulfate and coloured compounds isolated from the sewage of the sulfate-cellulose industry after biological purification. Solutions of the studied compounds (pH 7.0) quenched the bioluminescence of the luminescent bacterium Beneckea harveyi in proportion to their colour index and their content of phenol hydroxyls. This biotest based on quenching the luminescence of bacteria under the action of a toxic agent is rapid and highly reproducible. Therefore, it can be used for assaying the toxicity of sulfate-cellulose industry sewage containing hardly oxidizible coloured compounds. The toxic action of sewage can be predicted basing in the found dependence between the colour index of solutions containing coloured compounds and the intensity of bacterial bioluminescence.

[Elimination of quinones from aqueous environments by phenols and the effect of their mixtures on the luminescence of Beneckea harveyi bacteria]. / Eliminirovanie khinonov iz vodnykh sred fenolami i vliianie ikh smesei na svechenie bakterii Beneckea harveyi.

In the mixture of hydroquinone with other phenols the content of quinones has been measured by potentiometrical and polarographical methods. The decrease of quinone content in the mixture in comparison with the pure solution has been noted. The toxicity of solution estimated according to extinction of luminescence of bacteria at adding other phenols decreases.

[Quenching of the luminescence of phosphorescent bacteria as a test for assessing the toxicity of the phenol components of sewage]. / Gashenie liuminestsentsii svetiashchikhsia bakterii kak test dlia otsenki toksichnosti fenol'nykh komponentov stokov.

The object of this work was to estimate whether the luminescence of luminescent bacteria could be used as a biological test for assessment of the toxicity of phenol compounds in sewage. The toxicity of phenol compounds for luminescent bacteria was compared in terms of three indices: the quenching of luminescence, the inhibition of dehydrogenase activity and the ability to grow. Among the three indices, the quenching of luminescence was characterized by the highest sensitivity and the most rapid response.

A biometric study of tooth size and dental crowding.

A study was conducted for the purpose of comparing mesiodistal tooth widths between a group of patients with good tooth alignment and a group of patients with crowded dental arches. Crowded arches were defined as those with more than 4 mm. of space deficiency. The hypothesis tested was whether the arches with more than 4 mm. of crowding consistently had larger teeth than the ones with lesser or no crowding. The difference in sizes between the groups (forty males and forty females) for all teeth measured was found to be statistically significant (p less than 0.001). The multivariate data analysis indicated that the two groups were derived from two different populations and that the maxillary lateral incisors and second premolars and the mandibular canines and premolars were particularly different in these groups. It was also determined that the teeth in males were uniformly larger than in females, but not to a statistically significant level. There was less correlation, however, between the sex and the status of the tooth alignment in dental arches, so that both sexes had similar distribution of crowding versus noncrowding. On the basis of this study of eighty North American Caucasians, it is suggested that one should consider the sum of mesiodistal widths of teeth, in addition to the arch length analysis, in formulating an orthodontic treatment plan. When the cumulative tooth mass of the twenty permanent teeth is 140 mm. or more, the clinician may want to consider extraction therapy for such a case.

[Polarographic study of quinones formed during oxidation of caffeic and chlorogenic acids]. / Poliarograficheskoe izuchenie khinonov, obrazuiushchikhsia pri okislenii kofeinoi i khlorogenovoi kislot

Polarographic behaviour of a number of substituted ortho-benzenquinones was studied in weakly acidic, neutral and weakly caustic solutions (up to pH --9.0). Half-wave potential depends on the solution pH, indicating protonization of the carbonyl groups of the quinones. Protonization is probably stipulated by the hydroxonium ions. Protonization may take place not only under the action of water, but also under the effect of other acidic components, as indicated by the dependence of E1/2 on the undissociated acetic acid centrifugation. The condensation and polymerization reactions are characteristic for the ortho-quinones. A shift of the quinone potential indicates dimerization of the electrode products.

Effect of edgewise treatment and retention on manidbular incisors.

This study consisted of analyzing clinical records of fifty cases treated for correction of Class I malocclusion with varying degrees of bimaxillary protrusion and anterior mandibular crowding. Thrity of these cases required extraction of all four first premolars. Parameters characterizing changes in position of mandibular incisors during treatment with edgewise appliances and during retention and shortly afterward were studied. All the parameters indicated rather similar changes for the nonextraction and the extraction groups. The relapse of anterior mandibular crowding was significantly larger (p less than or equal to 0.05) in the nonextraction group. The IMPA and interincisal angle changed significantly more in the extraction group. Upon testing for validity of the mesiodistal to faciolingual indices, it was determined that they predicted stability of the achieved alignment of mandibular incisors. There were, however, individual cases in both groups which did not follow the central tendency. It was observed that the mesiodistal diameters of mandibular incisirs were somewhat larger in the extraction cases. There was only one pair of parameters that showed a moderately high intercorrelation (r equals 0.68); that was between correction of the anterior crowding and relapse of the intercanine expansion. It was observed that the more correction took place, the more readily expanded canines would relapse. An over-all impression is that the mandibular incisors change little in their position to each other and relative to the other structures of the mouth. The question remains: Is this due to our ability to control them well, or due to an inability to move and maintain them in their new position?