989 resultados para biological aspects


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The first synthesis of two selenyldeoxycyclitols (4-bromo-2-phenylselenyl conduritol F and 6-phenylselenylconduritol F) is reported via a chemoenzymatic enantioselective route. The key step of the synthesis is the selenolysis of a vinyl epoxide. The new compounds were evaluated for their capacity to inhibit the growth of different microorganisms using a modification of the agar diffusion technique with thin layer chromatography plates as support. (C) 2009 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Morphoanatomic aspects of Psidium guajava L. (Myrtaceae) leaves. Psidium guajava L. is a perennial shrub, native of tropical America used in Latin American traditional medicine as antimicrobial, antidiarrheic, and in the treatment of diabetes. The morphoanatomical characteristics and histochemistry of the crude drug, whole or powdered, used in pharmaceutical formulations were presented. The main diagnostic characters for the identification of its leaves in the present paper were: venation, trichomes type, number of layers of epidermal cells, mesophyll type and location/type of crystals of calcium oxalate. The morphoanatomical analysis has been proven to be a rapid method for quality control of the crude drug used for medicinal purposes.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

beta-Lactam antimicrobials are known to have a low concentration/therapeutic response. However, extending the period in which beta-lactam are free in the plasma does directly influence therapeutic outcomes. The objective of this study was to evaluate the influence of Pluronic (R) F68 on the antimicrobial activity of ceftazidime when admixed with aminophylline in parenteral solutions by the evaluation of its minimal inhibitory concentration (MIC) within 24 h. Ceftazidime, aminophylline, and Pluronics (R) F68 were evaluated using the MIC method against Escherichia coli and Pseudomonas aeruginosa, with these compounds individually and associated in the same parenteral solutions. When Pluronics (R) F68 was admixtured with ceftazidime alone or with ceftazidime and aminophylline, it was possible to observe lower MIC values not only at 24 h but also at 0 h for both microorganisms. This indicates that Pluronics (R) F68 may be able to enhance ceftazidime antimicrobial activity in the presence or absence of aminophylline. This fact suggests that Pluronics (R) F68 can be applied to allow the administration of ceftazidime under continuous infusion in parenteral solutions, beneficiating hospital pharmacotherapy. It may also be possible to reduce ceftazidime doses in formulations achieving the same therapeutic results. (C) 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:715-720, 2011

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The scope of this research work was to investigate biogas production and purification by a two-step bench-scale biological system, consisting of fed-batch pulse-feeding anaerobic digestion of mixed sludge, followed by methane enrichment of biogas by the use of the cyanobacterium Arthrospira platensis. The composition of biogas was nearly constant, and methane and carbon dioxide percentages ranged between 70.5-76.0% and 13.2-19.5%, respectively. Biogas yield reached a maximum value (about 0.4 m(biogas)(3)/kgCOD(i)) at 50 days-retention time and then gradually decreased with a decrease in the retention time. Biogas CO(2) was then used as a carbon source for A. platensis cultivation either under batch or fed-batch conditions. The mean cell productivity of fed-batch cultivation was about 15% higher than that observed during the last batch phase (0.035 +/- 0.006 g(DM)/L/d), likely due to the occurrence of some shading effect under batch growth conditions. The data of carbon dioxide removal from biogas revealed the existence of a linear relationship between the rates of A. platensis growth and carbon dioxide removal from biogas and allowed calculating carbon utilization efficiency for biomass production of almost 95%. (C) 2009 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this study was the design of a set of benzofuroxan derivatives as antimicrobial agents exploring the physicochemical properties of the related substituents. Topliss` decision tree approach was applied to select the substituent groups. Hierarchical cluster analysis was also performed to emphasize natural clusters and patterns. The compounds were obtained using two synthetic approaches for reducing the synthetic steps as well as improving the yield. The minimal inhibitory concentration method was employed to evaluate the activity against multidrug-resistant Staphylococcus aureus strains. The most active compound was 4-nitro-3-(trifluoromethyl)[N`-(benzofuroxan-5-yl) methylene] benzhydrazide (MIC range 12.7-11.4 mu g/mL), pointing out that the antimicrobial activity was indeed influenced by the hydrophobic and electron-withdrawing property of the substituent groups 3-CF(3) and 4-NO(2), respectively. (C) 2011 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The synthesis, structural aspects, pharmacological assays, and in vitro photoinduced cytotoxic properties of [Ru(NO)(ONO)(pc)] (pc = phthalocyanine) are described. Its biological effect on the B16F10 cell line was studied in the presence and absence of visible light irradiation. At comparable irradiation levels, [Ru(NO) (ONO)(pc)] was more effective than [Ru(pc)] at inhibiting cell growth, suggesting that occurrence of nitric oxide release following singlet oxygen production upon light irradiation may be an important mechanism by which the nitrosyl ruthenium complex exhibits enhanced biological activity in cells. Following visible light activation, the [Ru(NO)(ONO)(pc)] complex displayed increased potency in B16F10 cells upon modifications to the photoinduced dose; indeed, enhanced potency was detected when the nitrosyl ruthenium complex was encapsulated in a drug delivery system. The liposome containing the [Ru(NO)(ONO)(pc)] complex was over 25% more active than the corresponding ruthenium complex in phosphate buffer solution. The activity of the complex was directly proportional to the ruthenium amount present inside the cell, as determined by inductively coupled plasma mass spectroscopy. Flow cytometry analysis revealed that the photocytotoxic activity was mainly due to apoptosis. Furthermore, the vasorelaxation induced by [Ru(NO)(ONO)(pc)], proposed as NO carrier, was studied in rat isolated aorta. The observed vasodilation was concentration-dependent. Taken together, the present findings demonstrate that the [Ru(NO)(ONO)(pc)] complex induces vascular relaxation and could be a potent anti-tumor agent. Nitric oxide release following singlet oxygen production upon visible light irradiation on a nitrosyl ruthenium complex produces two radicals and may elicit phototoxic responses that may find useful applications in photodynamic therapy. Crown Copyright (C) 2011 Published by Elsevier Inc. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Several sesquiterpene lactone were synthesized and their inhibitive activities on phospholipase A(2) (PLA(2)) from Bothrops jararacussu venom were evaluated. Compounds Lac01 and Lac02 were efficient against PLA(2) edema-inducing, enzymatic and myotoxic activities and it reduces around 85% of myotoxicity and around 70% of edema-inducing activity. Lac05-Lac08 presented lower efficiency in inhibiting the biological activities studied and reduce the myotoxic and edema-inducing activities around only 15%. The enzymatic activity was significantly reduced. The values of inhibition constants (K(1)) for Lac01 and Lac02 were approximately 740 mu M, and for compounds Lac05-Lac08 the inhibition constants were approximately 7.622-9.240 mu M. The enzymatic kinetic studies show that the sesquiterpene lactones inhibit PLA(2) in a non-competitive manner. Some aspects of the structure-activity relationships (topologic, molecular and electronic parameters) were obtained using ab initio quantum calculations and analyzed by chemometric methods (HCA and PCA). The quantum chemistry calculations show that compounds with a higher capacity of inhibiting PLA(2) (Lac01-Lac04) present lower values of highest occupied molecular orbital (HOMO) energy and molecular volume (VOL) and bigger values of hydrophobicity (LogP). These results indicate some topologic aspects of the binding site of sesquiterpene lactone derivatives and PLA(2). (C) 2010 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Metarhizium spp. is an important worldwide group of entomopathogenic fungi used as an interesting alternative to chemical insecticides in programs of agricultural pest and disease vector control. Metarhizium conidia are important in fungal propagation and also are responsible for host infection. Despite their importance, several aspects of conidial biology, including their proteome, are still unknown. We have established conidial and mycelial proteome reference maps for Metarhizium acridum using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF MS). In all, 1130 +/- 102 and 1200 +/- 97 protein spots were detected in ungerminated conidia and fast-growing mycelia, respectively. Comparison of the two protein-expression profiles reveled that only 35 % of the protein spots were common to both developmental stages. Out of 94 2-DE protein spots (65 from conidia, 25 from mycelia and two common to both) analyzed using mass spectrometry, seven proteins from conidia, 15 from mycelia and one common to both stages were identified. The identified protein spots exclusive to conidia contained sequences similar to known fungal stress-protector proteins (such as heat shock proteins (HSP) and 6-phosphogluconate dehydrogenase) plus the fungal allergen Alt a 7, actin and the enzyme cobalamin-independent methionine synthase. The identified protein spots exclusive to mycelia included proteins involved in several cell housekeeping biological processes. Three proteins (HSP 90, 6-phosphogluconate dehydrogenase and allergen Alt a 7) were present in spots in conidial and mycelial gels, but they differed in their locations on the two gels. (c) 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Inaccurate species identification confounds insect ecological studies. Examining aspects of Trichogramma ecology pertinent to the novel insect resistance management strategy for future transgenic cotton, Gossypium hirsutum L., production in the Ord River Irrigation Area (ORIA) of Western Australia required accurate differentiation between morphologically similar Trichogramma species. Established molecular diagnostic methods for Trichogramma identification use species-specific sequence difference in the internal transcribed spacer (ITS)-2 chromosomal region; yet, difficulties arise discerning polymerase chain reaction (PCR) fragments of similar base pair length by gel electrophoresis. This necessitates the restriction enzyme digestion of PCR-amplified ITS-2 fragments to readily differentiate Trichogramma australicum Girault and Trichogramma pretiosum Riley. To overcome the time and expense associated with a two-step diagnostic procedure, we developed a “one-step” multiplex PCR technique using species-specific primers designed to the ITS-2 region. This approach allowed for a high-throughput analysis of samples as part of ongoing ecological studies examining Trichogramma biological control potential in the ORIA where these two species occur in sympatry.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Comparisons among loci with differing modes of inheritance can reveal unexpected aspects of population history. We employ a multilocus approach to ask whether two types of independently assorting mitochondrial DNAs (maternally and paternally inherited: F- and M-mtDNA) and a nuclear locus (ITS) yield concordant estimates of gene flow and population divergence. The blue mussel, Mytilus edulis, is distributed on both North American and European coastlines and these populations are separated by the waters of the Atlantic Ocean. Gene flow across the Atlantic Ocean differs among loci, with F-mtDNA and ITS showing an imprint of some genetic interchange and M-mtDNA showing no evidence for gene flow. Gene flow of F-mtDNA and ITS causes trans-Atlantic population divergence times to be greatly underestimated for these loci, although a single trans-Atlantic population divergence time (1.2 MYA) can be accommodated by considering all three loci in combination in a coalescent framework. The apparent lack of gene flow for M-mtDNA is not readily explained by different dispersal capacities of male and female mussels. A genetic barrier to M-mtDNA exchange between North American and European mussel populations is likely to explain the observed pattern, perhaps associated with the double uniparental system of mitochondrial DNA inheritance.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Nature-based tourism has grown in importance in recent decades, and strong links have been established between it and ecotourism. This reflects rising incomes, greater levels of educational attainment and changing values, especially in the Western world. Nature-based tourism is quite varied. Different types of such tourism are identified and their consequences for sustainability of their resource-base are briefly considered. The development and management of nature-based tourism involves many economic aspects, several of which are discussed. For example, one must consider the economics of reserving or protecting land for this type of tourism. What economic factors should be taken into account? Economists stress the importance of taking into account the opportunity costs involved in such a decision. This concept is explained. However, determining the net economic value of an area used for tourism is not straightforward. Techniques for doing this, such as the travel cost method and stated value methods, are introduced. Natural areas reserved for tourism may have economic value not only for tourism but also jointly for other purposes, such as conserving wildlife, maintaining hydrological cycles and so on. These other purposes, should be taken into account when considering the use of land for nature-based tourism. According to one economic point of view, land should be used in a way that maximises its total economic value. While this approach has its merits, it does not take into account the distribution of benefits from land use and its local impacts on income and employment. These can be quite important politically and for nature conservation, and are discussed. Finally, there is some discussion of whether fees charged to tourists for access to environmental resources should discriminate between domestic tourists and foreigners.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Polymorphus (Profilicollis) sphaerocephalus (Bremser in Rudolphi, 1819) Van Cleave, 1947 (Polymorphidae) cystacanths were recovered from 5 species of grapsid crabs (Paragrapsus gaimardii (Milne Edwards, 1837), Paragrapsus laevis (Dana, 1852), Paragrapsus quadridentatus (Milne Edwards, 1837), Brachynotus spinosus (Milne Edwards, 1853), and Cyclograpsus granulosus (Milne Edwards, 1853)) and 1 species of portunid crab (Nectocarcinus integrifrons (Linnaeus, 1766)) from intertidal zones in southern temperate waters of Australia. Cystacanths of Corynosoma stanleyi Smales, 1986 (Polymorphidae) were also recovered from P. gaimardii, P. quadridentatus, and C. granulosus. Polymorphus (P.) sphaerocephalus was the most prevalent (100%) in C. granulosus at Flinders I. and C. stanleyi was most prevalent (59.1%) in C. granulosus at Dunally Channel, Tasmania.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Three different aspects of the morphological organisation of deep-sea fish retinae are reviewed: First, questions of general cell biological relevance are addressed with respect to the development and proliferation patterns of photoreceptors, and problems associated with the growth of multibank retinae, and with outer segment renewal are discussed in situations where there is no direct contact between the retinal pigment epithelium and the tips of rod outer segments. The second part deals with the neural portion of the deep-sea fish retina. Cell densities are greatly reduced, yet neurohistochemistry demonstrates that all major neurotransmitters and neuropeptides found in other vertebrate retinae are also present in deep-sea fish. Quantitatively, convergence rates in unspecialised parts of the retina are similar to those in nocturnal mammals. The differentiation of horizontal cells makes it unlikely that species with more than a single visual pigment are capable of colour vision. In the third part. the diversity of deep-sea fish retinae is highlighted. Based on the topography of ganglion cells, species are identified with areae or foveae located in various parts of the retina, giving them a greatly improved spatial resolving power in specific parts of their visual fields. The highest degree of specialisation is found in tubular eyes. This is demonstrated in a case study of the scopelarchid retina, where as many as seven regions with different degrees of differentiation can be distinguished, ranging from an area giganto cellularis, regions with grouped rods to retinal diverticulum. (C) 1998 Elsevier Science Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Women's Health Australia (WHA) project is a longitudinal study of several cohorts of Australian women, which aims to examine the relationships between biological, psychological, social and lifestyle factors and women's physical health, emotional well-being, and their use of and satisfaction with health care. Using the Medicare database as a sampling frame (with oversampling of women from rural and remote areas), 106,000 women in the three age groups 18-23, 45-50 and 70-75 were sent an invitation to participate and a 24-page self-complete questionnaire. Reminder letters, a nation-wide publicity campaign, information brochures, a freecall number for inquiries, and the option of completing the questionnaire by telephone in English or in the respondent's own language, were used to encourage participation. Statutory regulations precluded telephone follow-up of non-respondents. Response rates were 41% (N = 14,792), 54% (N = 14,200) and 36% (N = 12,614) for the three age groups. Comparison with Australian census data indicated that the samples are reasonably representative of Australian women in these age groups, except fur a somewhat higher representation of women who are married or in a defacto relationship, and of women with post-school education. The most common reason for non-participation was lack of interest or time. Personal circumstances, objections to the questionnaire or specific items in it, and concerns about confidentiality were the other main reasons. Recruitment of three representative age-group cohorts of women, and the maintenance of these cohorts over a number of years, will provide a valuable opportunity to examine associations over time between aspects of women's lives and their physical and emotional health and well-being.