Acetylation of cellulose in LiCl-N,N-dimethylacetamide: first report on the correlation between the reaction efficiency and the aggregation number of dissolved cellulose

The acylation of three cellulose samples by acetic anhydride, Ac(2)O, in the solvent system LiCl/N,N-dimethylacetamide, DMAc (4 h, 110 A degrees C), has been revisited in order to investigate the dependence of the reaction efficiency on the structural characteristics of cellulose, and its aggregation in solution. The cellulose samples employed included microcrystalline, MCC; mercerized cotton linters, M-cotton, and mercerized sisal, M-sisal. The reaction efficiency expresses the relationship between the degree of substitution, DS, of the ester obtained, and the molar ratio Ac(2)O/AGU (anhydroglucose unit of the biopolymer); 100% efficiency means obtaining DS = 3 at Ac(2)O/AGU = 3. For all celluloses, the dependence of DS on Ac(2)O/AGU is described by an exponential decay equation: DS = DS(o) - Ae(-[(Ac2O/AGU)/B]); (A) and (B) are regression coefficients, and DS(o) is the calculated maximum degree of substitution, achieved under the conditions of each experiment. Values of (B) are clearly dependent on the cellulose employed: B((M-cotton)) > B((M-sisal)) > B((MCC)); they correlate qualitatively with the degree of polymerization of cellulose, and linearly with the aggregation number, N(agg), of the dissolved biopolymer, as calculated from static light scattering measurements: (B) = 1.709 + 0.034 N(agg). To our knowledge, this is the first report on the latter correlation; it shows the importance of the physical state of dissolved cellulose, and serves to explain, in part, the need to use distinct reaction conditions for MCC and fibrous celluloses, in particular Ac(2)O/AGU, time, temperature.

Comparasion of two minimally invasive methods on the longevity of glass ionomer cement restorations: short-term results of a pilot study

The purpose of this study was to evaluate the clinical performance of glass ionomer cement (GIC) restorations comparing two minimally invasive methods in permanent teeth after 12 months. Fifty pregnant women (second trimester of pregnancy), mean age 22 ± 5.30 years, were treated by two previously trained operators. The treatment approaches tested were: chemomechanical method (CarisolvTM; MediTeam) and atraumatic restorative treatment (ART). A split-mouth study design was used in which the two treatments were randomly placed in 50 matched pairs of permanent teeth. The chemomechanical method (CM) was the test group and the ART was the control group. The treatments were performed in Public Health Centers. The tested restorative material was a high-strength GIC (Ketac Molar; 3M/ESPE). The restorations were placed according to the ART guidelines. Two calibrated independent examiners evaluated the restorations in accordance with ART criteria. The inter-examiner kappa was 0.97. Data were analyzed using 95% confidence interval on the binomial distribution and Fisher's exact test at 5% significance level. In a 12-month follow-up, 86% of the restorations were evaluated. In the test group (CM), 100% (CI=93.3-100%) of the restorations were considered successful. In the control group (ART) 97.6% (CI=87.4-99.9%) of the restorations were considered successful and 2.4% unsuccessful (marginal defect >0.5 mm). There was no statistically significant difference between the 12-mounth success rate for both groups (Fisher's exact test: P=0.49) and between the two operators (Fisher's exact test: P=1.00). Both minimally invasive methods, chemomechanical method and ART, showed a similar clinical performance after 12 months of follow up.

Use of flowable composite as intermediary layer in non-carious cervical lesions restored with composite resin: 48-month follow-up

PURPOSE: In this case report, the clinical performance of a microhybrid resin composite placed with or without a flowable resin composite was compared, over a 48-month period. CASE DESCRIPTION: The patient of this case report presented 2 pairs of equivalent cervical abfraction lesions, under occlusion. Four restorations were placed in teeth 34, 35, 44 and 45. The restorations were divided into groups (Single Bond + Filtek-Flow + Filtek Z250 or Single Bond + Filtek Z250) and the materials were applied according to the manufactures instructions. Two previously calibrated operators placed the restorations and two other independent examiners evaluated the restorations at baseline and after 48 months, according to the USPHS criteria and modified criteria for color match. CONCLUSION: After 48 months of evaluation the lesions restored with Filtek-Flow as a liner under Filtek Z250 did not show better clinical performance than the restorations without Filtek-Flow. All restorations showed a trend toward dark yellowing after 48 months.

Antiplatelet activity of Croton celditifolius

Croton celtidifolius Baill is a tree found in the Atlantic Forest South of Brazil, mainly in Santa Catarina. The bark and leaf infusions of this medicinal plant have been popularly used for the treatment of inflammatory diseases. The anti-aggregant activity of C. celtidifolius crude extract (CE) and the column chromatography (CC) isolated compounds flavonoids, catechin and gallocatechin were evaluated in human blood platelets. The platelet-rich plasma (PRP) was incubated with different concentrations of flavonóides (50 - 200 µg/mL) to be tested before platelet aggregation was induced by the agonists adenosine 5'diphosphate (ADP) and collagen. At 200 µg/mL the CE, catechin and gallocatechin markedly inhibited platelet aggregation with the aggregant agents. Using ATP production as an index of platelet secretory capacity, we observed a decreased production of ATP in platelets treated with flavonoids when stimulated by collagen. On the other hand, the flavonoids did not promote inhibitory effect on prothrombin time (PT), thromboplastin time (APTT) and thrombin time (TT). In conclusion, these observations suggest that C. celtidifolius is likely to exert an inhibitory action on platelets in vitro by suppressing secretion and platelet aggregation.

Novos paradigmas e velhos discursos: analisando processos de adolescentes em conflito com a lei

Este artigo evidencia análises contidas na dissertação cujo objetivo foi analisar os discursos dos operadores jurídico-sociais em processos judiciais de Varas da Infância e Juventude de duas cidades brasileiras. Os direitos das crianças e adolescentes, a questão social e a análise do discurso configuraram-se como referenciais teóricos e de análise. Resultados evidenciaram discursos de proteção e revelaram também a intenção de punição. A questão social foi ignorada pelos operadores a despeito dos contextos em que ocorreram as infrações.

Some aspects of acetylation of untreated and mercerized sisal cellulose

We report here on some aspects of the acetylation in LiCl/N,N-dimethylacetamide, DMAc, of untreated and mercerized sisal cellulose, hereafter designated as sisal and M-sisal, respectively. Fiber mercerization by NaOH solution has resulted in the following changes: 29.9% decrease in the index of crystallinity; 16.2% decrease in the degree of polymerization and 9.3% increase in α-cellulose content. A light scattering study of solutions of sisal, M-sisal, microcrystalline and cotton celluloses in LiCl/DMAc has shown that they are present as aggregates, with (an apparent) average aggregation numbers of 5.2, 3.2, 9.8, and 35.3, respectively. The presence of these aggregates affects the accessibility of cellulose during its functionalization. A study of the evolution of the degree of substitution, DS, of cellulose acetate as a function of reaction time showed an increase up to 5 h, followed by a decrease at 7 h. Possible reasons for this decrease are discussed. As expected, M-sisal gave a higher DS that its untreated counterpart.

Agregação de cadeias de acetatos de celulose em LiCl/DMAc: avaliação via viscosimetria

Celulose de linter foi acetilada, visando obter acetatos de celulose com diferentes Graus de Substituição (GS) em meio homogêneo, usando cloreto de lítio/N,N-dimetilacetamida (LiCl/DMAc) como sistema de solvente, e anidrido acético como reagente acetilante. A agregação entre cadeias de celulose ou acetatos de celulose (GS 0,8, 1,5 e 2,0) em solução foi avaliada através de medidas viscosimétricas. Os resultados mostraram que a formação de agregados no sistema de solvente utilizado (LiCl/DMAc) é diferente para celulose e acetatos, e dependente da temperatura e do GS, no caso dos acetatos. Este trabalho corresponde à primeira etapa de um estudo em que se pretende preparar filmes de acetatos, assim como de acetatos reforçados com celulose, diretamente a partir de soluções destes em LiCl/DMAc. Os resultados apresentados permitem uma escolha melhor embasada do intervalo de concentração mais adequado para preparação de filmes, a partir de soluções de acetatos e celulose nesse sistema de solvente.

Influência de diferentes sistemas de solvente água-etanol sobre as propriedades físico-químicas e espectroscópicas dos compostos macrocíclicos feofitina e clorofila α

This work focus on the influence of solvent on the photophysical properties of chlorophyll α and pheophytin. Both compounds are related to the photosynthesis process and are considered prototypes of photosensitizers in Photodynamic Therapy. Fluorescence measurements were developed using water/ethanol mixtures at different compositions, since both solvents could be employed in biological applications. The spectroscopic properties of these compounds undergo profound changes depending on water content in the ethanol due to auto-aggregation processes. The major hydrophobicity and the lower dielectric constant of ethanol when compared with water precluded significantly the auto-aggregation process of these compounds.

Confiabilidade da informação sobre hospitalizações por causas externas de um hospital público em São José dos Campos, São Paulo, Brasil

OBJETIVO: Conhecer a qualidade dos dados de internação por causas externas em São José dos Campos, São Paulo. MÉTODO: Foram estudadas as internações pelo Sistema Único de Saúde por lesões decorrentes de causas externas no primeiro semestre de 2003, no Hospital Municipal, referência para o atendimento ao trauma no Município, por meio da comparação dos dados registrados no Sistema de Informações Hospitalares com os prontuários de 990 internações. A concordância das variáveis relativas à vítima, à internação e ao agravo foi avaliada pela taxa bruta de concordância e pelo coeficiente Kappa. As lesões e as causas externas foram codificadas segundo a 10ª revisão da Classificação Internacional de Doenças, respectivamente, capítulos XIX e XX. RESULTADOS: A taxa de concordância bruta foi de boa qualidade para as variáveis relativas à vítima e à internação, variando de 89,0% a 99,2%. As lesões tiveram concordância ótima, exceto os traumatismos do pescoço (k=0,73), traumatismos múltiplos (k=0,67) e fraturas do tórax (k=0,49). As causas externas tiveram concordância ótima para acidentes de transporte (k=0,90) e quedas (k=0,83). A confiabilidade foi menor para agressões (k=0,50), causas indeterminadas (k=0,37), e complicações da assistência médica (k=0,03). Houve concordância ótima nos acidentes de transporte em pedestres, ciclistas e motociclistas. CONCLUSÃO: A maioria das variáveis de estudo teve boa qualidade no nível de agregação analisado. Algumas variáveis relativas à vítima e alguns tipos de causas externas necessitam de aperfeiçoamento da qualidade dos dados. O perfil da morbidade hospitalar encontrado confirmou os acidentes de transporte como importante causa externa de internação hospitalar no Município.

Recovery and upgrading bovine rumen protein by extrusion: effect of lipid content on protein disulphide cross-linking, solubility and molecular weight

Bovine rumen protein with two levels of residual lipids (1.9 per cent or 3.8 per cent) was subjected to thermoplastic extrusion under different temperatures and moisture contents. Protein solubility in different buffers, disulphide cross-linking and molecular weight distribution were determined on the extrudates. After extrusion, samples with 1.9 per cent residual lipids content had a higher concentration of protein insoluble by undetermined forces, irrespective of feed moisture and processing temperature used. Lipid content of 3.8 per cent in the feed material resulted in more protein participating in the extrudate network through non-covalent interactions (hydrophobic and electrostatic) and disulphide bonds. A small dependency of the extrusion process on moisture and temperature and a marked dependency on lipid content, especially phospholipid, was observed, Electrophoresis under non-reducing conditions showed that protein extrusion with low feed moisture promoted high molecular breakdown inside the barrel, probably due to intense shear force, and further protein aggregation at the die end

A rational protocol for the successful crystallization of l-amino-acid oxidase from Bothrops atrox

Despite the valuable contributions of robotics and high-throughput approaches to protein crystallization, the role of an experienced crystallographer in the evaluation and rationalization of a crystallization process is still crucial to obtaining crystals suitable for X-ray diffraction measurements. In this work, the difficult task of crystallizing the flavoenzyme l-amino-acid oxidase purified from Bothrops atrox snake venom was overcome by the development of a protocol that first required the identification of a non-amorphous precipitate as a promising crystallization condition followed by the implementation of a methodology that combined crystallization in the presence of oil and seeding techniques. Crystals were obtained and a complete data set was collected to 2.3 A resolution. The crystals belonged to space group P2(1), with unit-cell parameters a = 73.64, b = 123.92, c = 105.08 A, beta = 96.03 degrees. There were four protein subunits in the asymmetric unit, which gave a Matthews coefficient V (M) of 2.12 A3 Da-1, corresponding to 42% solvent content. The structure has been solved by molecular-replacement techniques.

ASSOCIATION OF A MYOSIN MOTOR WITH MEMBRANE-BOUNDED PIGMENT GRANULES IN FRESHWATER SHRIMP CHROMATOPHORES: EVIDENCE FROM THE NITELLA ACTIN-CABLE ASSAY

We have adapted an actin-mosin motility assay to examine the interactions in vitro between actin cables isolated from the giant internodal cells of the freshwater alga, Nitella, and pigment granules extracted from red ovarian chromatophores of the freshwater palaemonid shrimp, Macrobrachium olfersi. The chromatophore pigment mass consists of large (0.5-1.0-mu m diameter) membrane-bounded granules, and small (140-nm diameter), a membranous granules, both structurally continuous with the abundant smooth endoplasmic reticulum. Our previous immunocytochemical studies show a myosin motor to be stably associated with the pigment mass; however, to which granule type or membrane the myosin motor is attached is unclear. Here, we show that sodium vanadate, a myosin ATPase inhibitor, markedly increases the affinity of isolated, large, membrane-bounded granules for Nitella actin cables to which they become permanently attached. This interaction does not occur in granule preparations containing ATP with uninhibited, active myosin without vanadate. We propose that a stable state of elevated affinity is established between the granule-located myosin motor and the Nitella actin cables, resulting from a vanadate-inhibited acto-myosin-ADP complex. This finding provides further evidence for a myosin motor positioned on the surface of the membrane-bounded pigment granules in shrimp ovarian chromatophores.

Variations on a theme: diversification of cuticular hydrocarbons in a clade of cactophilic Drosophila

Background: We characterized variation and chemical composition of epicuticular hydrocarbons (CHCs) in the seven species of the Drosophila buzzatii cluster with gas chromatography/mass spectrometry. Despite the critical role of CHCs in providing resistance to desiccation and involvement in communication, such as courtship behavior, mating, and aggregation, few studies have investigated how CHC profiles evolve within and between species in a phylogenetic context. We analyzed quantitative differences in CHC profiles in populations of the D. buzzatii species cluster in order to assess the concordance of CHC differentiation with species divergence. Results: Thirty-six CHC components were scored in single fly extracts with carbon chain lengths ranging from C(29) to C(39), including methyl-branched alkanes, n alkenes, and alkadienes. Multivariate analysis of variance revealed that CHC amounts were significantly different among all species and canonical discriminant function (CDF) analysis resolved all species into distinct, non-overlapping groups. Significant intraspecific variation was found in different populations of D. serido suggesting that this taxon is comprised of at least two species. We summarized CHC variation using CDF analysis and mapped the first five CHC canonical variates (CVs) onto an independently derived period (per) gene + chromosome inversion + mtDNA COI gene for each sex. We found that the COI sequences were not phylogenetically informative due to introgression between some species, so only per + inversion data were used. Positive phylogenetic signal was observed mainly for CV1 when parsimony methods and the test for serial independence (TFSI) were used. These results changed when no outgroup species were included in the analysis and phylogenetic signal was then observed for female CV3 and/or CV4 and male CV4 and CV5. Finally, removal of divergent populations of D. serido significantly increased the amount of phylogenetic signal as up to four out of five CVs then displayed positive phylogenetic signal. Conclusions: CHCs were conserved among species while quantitative differences in CHC profiles between populations and species were statistically significant. Most CHCs were species-, population-, and sex-specific. Mapping CHCs onto an independently derived phylogeny revealed that a significant portion of CHC variation was explained by species' systematic affinities indicating phylogenetic conservatism in the evolution of these hydrocarbon arrays, presumptive waterproofing compounds and courtship signals as in many other drosophilid species.

EXISTENCE RESULTS FOR NEUTRAL INTEGRO-DIFFERENTIAL EQUATIONS WITH UNBOUNDED DELAY

In this paper we discuss the existence of mild, strict and classical solutions for a class of abstract integro-differential equations in Banach spaces. Some applications to ordinary and partial integro-differential equations are considered.

Existence Results for Abstract Partial Neutral Integro-differential Equation with Unbounded Delay

In this paper we study the existence and regularity of mild solutions for a class of abstract partial neutral integro-differential equations with unbounded delay.