RESUMO
Studying ocular biomechanics presents apparent interest because of certain clinical situations when in vivo evaluation of mechanical properties can help with both diagnosis and treatment. This literature review considers the approaches to studying deformation properties of various ocular structures: dynamometric methods, elastotonometry, ophthalmic mechanography, photoelasticity method, ultrasound methods, analysis of pneumatic applanation of the cornea, atomic force microscopy, holographic interferometry, optical coherence elastography. Knowledge of the particularities of tissue deformation during examination with various methods can expand our understanding of the mechanisms of pathological changes in different structures of the organ of vision, which can help develop new methods of diagnosis and treatment.
Assuntos
Córnea , Interferometria , Fenômenos Biomecânicos , Córnea/diagnóstico por imagem , Humanos , Interferometria/métodosRESUMO
Most foreign authors currently recommend the protocol and charts developed for the Early Treatment Diabetic Retinopathy Study (ETDRS) as the gold standard for evaluation of visual acuity (VA) in clinical trials and studies. Not every medical facility has equipment required for performing visometry by that method, while Sivtsev tables are found universally. OBJECTIVE: To compare ETDRS and the more common Sivtsev visometry methods. MATERIAL AND METHODS: The study included 100 volunteers - students of the Sechenov University. All participants were examined for VA in both eyes without correction using ETDRS "R" chart and Sivtsev table. Visometry with "R" ETDRS chart involved calculation of the number of named letters, then the number was translated into logarithmic notation by the conventional method. Sivtsev visometry findings were translated into logarithmic notation by two methods: first - standard, line-by-line, second - experimental, letter-by-letter. Subjects were divided into two groups: high VA (higher than 0.4 in decimal scale) and low VA - everyone else. RESULTS: The best agreement with ETDRS was found in letter-by-letter method of Sivtsev table interpretation, especially in the group with high VA with the lowest 95% limits of agreement (LoA) of ±0.157 logMAR, or 8 letters on ETDRS. Clinically significant were also LoA in comparison of ETDRS with line-by-line calculation method in the group with high VA and in letter-by-letter method without dividing groups by VA. CONCLUSION: The use of Sivtsev table in standardized multicenter studies is only reasonable when the ETDRS charts are unavailable.
Assuntos
Retinopatia Diabética , Testes Visuais , Olho , Humanos , Reprodutibilidade dos Testes , Transtornos da Visão , Testes Visuais/métodos , Acuidade VisualRESUMO
The application of atomic force microscopy (AFM) in ophthalmology is considered with respect of the classical anatomical division of the eye into anterior and posterior segments. The review presents the findings of published research studies that involved AFM as a method for assessing anatomical and functional condition of the structures of anterior eye segment. One significant line of research is related to the use of AFM technologies for evaluation of morphological and biomechanical characteristics of various parts of the eye lens. That topic draws interest due to the need of furthering the understanding of cataractogenesis, as well as the significance of the anatomical and functional characteristics of the lens capsule in the mechanism of accommodation and modern phaco surgery.
Assuntos
Cristalino , Acomodação Ocular , Elasticidade , Microscopia de Força AtômicaRESUMO
Starting from 2009, monitoring studies of swamp regimes have been conducted at the swampland station located in the north-eastern Altai. Here, we present the results of biological activity (indices of microorganisms abundance, respirometric indicator, catalase activity) in peat deposits of eutrophic (Turochak) and mesotrophic (Kutyushskoye) swamps during 2012-2013 vegetation periods with different levels of marsh water and oxidation-reduction conditions.
Assuntos
Gases de Efeito Estufa/metabolismo , Microbiologia do Solo , Áreas Alagadas , SibériaRESUMO
The abundance and taxonomic structure of soil bacterial communities have been studied in different geomorphological parts of the Yakhroma floodplain. It has been found that the numbers of bacteria reach a peak in calcareous peat soil under forest near the floodplain terrace, decreasing to a minimum in soddy alluvial soil near the riverbed. All soils are characterized by the presence of different ecological-trophic bacterial groups capable of peat destruction. Seasonal dynamics of the structure of bacterial communities and, in some soil types, its spatial dynamics accounted for by changes in the botanical structure of peat across its profile have been revealed. All peat soils in the floodplain have high contents of organic matter and neutral pH and, therefore, are favorable biotopes for the development of saprotrophic bacteria. This, in turn, largely accounts for high productivity and stability of this agroecosystem as a whole.
Assuntos
Bactérias/crescimento & desenvolvimento , Ecossistema , Microbiologia do Solo , Solo , Rios , Federação RussaRESUMO
Dynamics of the taxonomic structure of epiphytic bacterial communities of the rhizosphere and phyllosphere of seven weed species was studied. The major types of isolated organisms were identified using phenotypic and molecular biological approaches. Dispersion analysis revealed that the ontogenesis stage and plant organ were the factors with the greatest effect on the taxonomic structure of the communities. The dominant microorganisms of weeds were similar to those of cultivated plants. The minor components revealed in the spectra of bacterial communities of weeds belonged to poorly studied genera of chemolithotrophic proteobacteria.
Assuntos
Plantas Daninhas/microbiologia , Proteobactérias/classificação , Proteobactérias/genéticaRESUMO
The microcosm method was used to demonstrate an increase in bacterial numbers and drastic changes in the taxonomic structure of saprotrophic bacteria as a result of mechanical grinding of Sphagnum moss. Ekkrisotrophic agrobacteria predominant in untreated moss were replaced by hydrolytic bacteria. Molecular biological approaches revealed such specific hydrolytic bacteria as Janthinobacterium agaricum and Streptomyces purpurascens among the dominant taxa. The application of kinetic technique for determination of the physiological state of bacteria in situ revealed higher functional diversity of hydrolytic bacteria in ground moss than in untreated samples. A considerable decrease of the C/N ratio in ground samples of living Sphagnum incubated using the microcosm technique indicated decomposition of this substrate.
Assuntos
Consórcios Microbianos , Sphagnopsida/química , Sphagnopsida/microbiologia , Biodiversidade , Carbono/metabolismo , Nitrogênio/metabolismo , Oxalobacteraceae/isolamento & purificação , Oxalobacteraceae/metabolismo , Microbiologia do Solo , Streptomyces/isolamento & purificaçãoRESUMO
Very large microbial biomass was revealed in peat bogs by means of fluorescence microscopy. In ombrotrophic peatlands, the pool of the dry-weight microbial biomass in the 1.5-m layer constituted 3-4 t/ha and was twice as high as in the minerotrophic peat bogs. Fungal biomass was predominant (55-99%) in ombrotrophic peatlands, while bacterial biomass predominated in minerotrophic peatlands (55-86%). In ombrotrophic peatlands, the microbial biomass was concentrated in the upper layers, while in minerotrophic peatlands, it was uniformly distributed in the bulk. After drainage, the microbial pool in the ombrotrophic peatlands increased twofold; that in the minerotrophic peatlands remained at the same level. The potential activity of nitrogen fixation and denitrification was revealed across the whole profile of the peatlands. The average values of these potential activities were five times higher in the minerotrophic peatlands, where bacterial biomass predominated.
Assuntos
Bactérias/isolamento & purificação , Biomassa , Fungos/isolamento & purificação , Microbiologia do Solo , Cromatografia Gasosa , Contagem de Colônia Microbiana , Fixação de Nitrogênio , Federação Russa , Solo/análise , Áreas AlagadasRESUMO
The population density of bacteria in peat deposits along the landscape profile of the Vasyugan Marsh has been found to be as high as tens of millions of CFU/g peat. The abundance and diversity of bacteria increased with depth within the peat deposit, correlating with an increasing level of peat degradation. Variations in these parameters with depth and season were greater in peat deposits located in transaccumulative and transitional positions than in the sedge-sphagnum bogs located at the eluvial region of the profile. In the upper 1-m-thick layer of the peat deposits studied, bacilli, represented by five species, dominated, whereas, in the deeper layers, spirilla and myxobacteria prevailed. These bacteria were major degraders of plant polymers. Unlike the bacterial communities found in the peat deposits of European Russia, the dominant taxa in the studied peat deposits of Western Siberia are represented by bacteria resistant to extreme conditions.
Assuntos
Bactérias/isolamento & purificação , Microbiologia do Solo , Bactérias/classificação , Bactérias/metabolismo , Biodegradação Ambiental , Contagem de Colônia Microbiana , Plantas/metabolismo , Polímeros/metabolismo , Sibéria , Solo/análiseRESUMO
Some microbiological parameters, such as the fungal mycelium length, the number of fungal spores, the distribution profiles of micromycetes, the viability of fungal propagules, the length distribution of micromycete hyphae, and the proportion between fungal spores and yeastlike cells, can be used to determine the degree of soil contamination with oil and the concentration that is inhibitory to the micromycete complexes of highmoor peats.
Assuntos
Biomassa , Fungos/efeitos dos fármacos , Óleos/farmacologia , Microbiologia do Solo , Poluentes do Solo/farmacologia , Fungos/fisiologia , PetróleoRESUMO
The analysis of the micromycete complexes of oligotrophic peat deposits in the Vasyugan Marsh by direct count and culture methods showed that the micromycete carbon comprises no more than 3% of the total peat carbon and that the microscopic fungal biomass varies from 2 to 13 tons/hectare, depending on the season and the peat deposit thickness. Fungal spores were found in all layers of the peat deposits, whereas the mycelium was found only in the active peat layer. The high abundance of eukaryotic cells in the peats was due to the presence of yeastlike cells rather than fungal spores. Analyses by culture methods showed that micromycetes were present in all peat layers and that their abundance tended to decrease with depth, except for yeasts, which were uniformly distributed in a vertical direction. The micromycete complexes of the peat deposits were similar in the diversity and abundance of dominant species but differed in the composition of minor species. Peat yeasts were dominated by ascomycetes.
Assuntos
Fungos/isolamento & purificação , Microbiologia do Solo , Ascomicetos/isolamento & purificação , Contagem de Colônia Microbiana , Fungos/classificação , Fungos Mitospóricos/isolamento & purificação , Estações do Ano , SibériaRESUMO
The initial concentration of prokaryotic microorganisms, the type of their growth, doubling time, and the growth dynamics of bacteria and actinomycetes in three types of soil (meadow, chestnut, and soddy forest) were evaluated by the luminescence microscopic analysis of soil samples incubated in a humid chamber for 1 day. Soddy forest and chestnut soils differed in most of the parameters analyzed. Meadow soil was close to soddy forest soil in some parameters and to chestnut soil in other parameters. All soil suspensions exhibited high growth rates of bacteria and actinomycetes, indicating that the fraction of viable microorganisms in the soils was high.
Assuntos
Actinobacteria/isolamento & purificação , Bactérias/isolamento & purificação , Microbiologia do Solo/normas , Actinobacteria/crescimento & desenvolvimento , Bactérias/crescimento & desenvolvimento , Técnicas Bacteriológicas , Medições Luminescentes , Fatores de TempoRESUMO
The study of the root-associated microbial complexes of affected and healthy rose plants of two cultivars (Grand gala and Royal velvet) grown in a greenhouse showed that the biomass of eukaryotic microorganisms in the rhizoplane and rhizosphere of healthy rose plants and in the surrounding soil was considerably lower than in the same loci of affected plants. In contrast, the biomass of root-associated prokaryotic microorganisms was higher in the case of healthy than in the case of affected rose plants. The root-associated bacterial complexes of both affected and healthy rose plants were dominated by the genera Arthrobacter, Rhodococcus, and Myxobacterium and did not contain phytopathogenic bacteria. The root-associated fungal complex of healthy roses was dominated by fungi of the genus Trichoderma, whereas that of the affected rose plants was dominated by the species Aureobasidium microstictum. The affected cane cuttings and cankers occurring on affected canes were found to contain Coniothyrium fuckelii (the causal fungus of rose stem canker) and sclerotia of Botrytis cinerea (the causal fungus of gray rot). The micromycete complex of healthy rose plants was not so diverse as was the micromycete complex of affected rose plants.
Assuntos
Bactérias/isolamento & purificação , Rosa/microbiologia , Microbiologia do Solo , Arthrobacter/isolamento & purificação , Bactérias/classificação , Myxococcales/isolamento & purificação , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia , Rhodococcus/isolamento & purificação , Especificidade da EspécieRESUMO
The synecological analysis of bacterial communities from the Protva River flood-plain biogeocenosis showed that all of the horizons contain spirilla, which are typical hydrobionts, and pigmented coryneform bacteria associated with the herbaceous plants of the flood-plain meadows. The alluvial meadow soils of the inundated regions of the floodplain differed from the unflooded regions of the flood-plain in that they had a more diverse bacterial population continuously distributed over the soil profile.
Assuntos
Bactérias/classificação , Ecossistema , Microbiologia do Solo , Água Doce/microbiologia , Federação RussaRESUMO
General regularities in the structure of the microbial communities of southern taiga soil ecosystems and taxonomic differences between the microbial communities of soils with different hydrothermal characteristics are discussed with reference to the main types of soils of the Central State Forest Biosphere Reserve.