Nanogel-Based Filler-Matrix Interphase for Polymerization Stress Reduction.

A novel filler-resin matrix interphase structure was developed and evaluated for dental composite restoratives. Nanogel additives were chemically attached to the filler surface to use this created interphase as a potential source of compliance to minimize stress development during polymerization. In addition, we evaluated the effects of free nanogel dispersion into the resin matrix, combined or not with nanogel-modified fillers. Nanogels with varied characteristics were synthesized (i.e., size, 5 and 11 nm; glass transition temperature, 28 °C to 65 °C). Glass fillers were treated with trimethoxyvinylsilane and further reacted with thiol-functionalized nanogels via a free radical thiol-ene reaction. γ-Methacryloxypropyltrimethoxysilane-surface treated fillers were used as a control. Composites were formulated with BisGMA/TEGDMA resin blend with 60 wt% fillers with nanogel-modified fillers and/or free nanogel additives at 15 wt% in the resin phase. Polymerization kinetics, polymerization stress, volumetric shrinkage, and rheological and mechanical properties were evaluated to provide comprehensive characterization. Nanogel-modified fillers significantly reduced the polymerization stress from 2.2 MPa to 1.7 to 1.4 MPa, resulting in 20% stress reduction. A significantly greater nanogel content was required to generate the same magnitude stress reduction when the nanogels were dispersed only in the resin phase. When the nanogel-modified filler surface treatment and resin-dispersed nanogel strategies were combined, there was a stress reduction of 50% (values of 1.2 to 1.1 MPa). Polymerization rate and volumetric shrinkage were significantly reduced for systems with nanogel additives into the resin. Notably, the flexural modulus of the materials was not compromised, although a slight reduction in flexural strength associated with the nanogel-modified interphase was observed. Overall, modest amounts of free nanogel additives in the resin phase can be effectively combined with a limited nanogel content filler-resin interphase to lower volumetric shrinkage and dramatically reduce overall polymerization stress of composites.

Construction of monomer-free, highly crosslinked, water-compatible polymers.

Polymeric dental adhesives require the formation of densely crosslinked network structures to best ensure mechanical strength and durability in clinical service. Monomeric precursors to these materials typically consist of mixtures of hydrophilic and hydrophobic components that potentially undergo phase separation in the presence of low concentrations of water, which is detrimental to material performance and has motivated significant investigation into formulations that reduce this effect. We have investigated an approach to network formation based on nanogels that are dispersed in inert solvent and directly polymerized into crosslinked polymers. Monomers of various hydrophilic or hydrophobic characteristics were copolymerized into particulate nanogels bearing internal and external polymerizable functionality. Nanogel dispersions were stable at high concentrations in acetone or, with some exceptions, in water and produced networks with a wide range of mechanical properties. Networks formed rapidly upon light activation and reached high conversion with extremely low volumetric shrinkage. Prepolymerizing monomers into reactive nanostructures significantly changes how hydrophobic materials respond to water compared with networks obtained from polymerizations involving free monomer. The modulus of fully hydrated networks formed solely from nanogels was shown to equal or exceed the modulus in the dry state for networks based on nanogels containing a hydrophobic dimethacrylate and hydrophilic monomethacrylate, a result that was not observed in a hydroxyethyl methacrylate (HEMA) homopolymer or in networks formed from nanogels copolymerized with HEMA. These results highlight the unique approach to network development from nanoscale precursors and properties that have direct implications in functional dental materials.

Improved dental adhesive formulations based on reactive nanogel additives.

Current challenges in adhesive dentistry include over-hydrophilic bonding formulations, which facilitate water percolation through the hybrid layer and result in unreliable bonded interfaces. This study introduces nanogel-modified adhesives as a way to control the material's hydrophobic character without changing the basic monomer formulation (keeping water-chasing capacity and operatory techniques unaltered). Nanogel additives of varied hydrophobicity were synthesized in solution, rendering 10- to 100-nm-sized particles. A model BisGMA/HEMA solvated adhesive was prepared (control), to which reactive nanogels were added. The increase in adhesive viscosity did not impair solvent removal by air-thinning. The degree of conversion in the adhesive was similar between control and nanogel-modified materials, while the bulk dry and, particularly, the wet mechanical properties were significantly improved through nanogel-based network reinforcement and reduced water solubility. As preliminary validation of this approach, short-term micro-tensile bond strengths to acid-etched and primed dentin were significantly enhanced by nanogel inclusion in the adhesive resins.

[Child and adolescent mortality due to external causes: trends from 1979 to 1995]. / Mortalidade por causas externas em crianças e adolescentes: tendências de 1979 a 1995.

OBJECTIVE: To analyze the magnitude and trends of mortality due to external causes in specific age groups, from 0 to 19 years old in a population living in the city of Recife, Brazil, from 1979 to 1995. METHODS: Data from the Mortality Data System of the Ministry of Health and Health Department of Pernambuco State was used. The studied population, aged 0 to 19 years old, represented 41.8% of total city population in 1991. A time series exploratory ecological model was created to analyze trends in mortality coefficients due to external causes. Using simple linear regression these coefficients were assessed in specific age groups categorized by gender. RESULTS AND CONCLUSIONS: In the time series, mortality coefficients due to external causes showed an increasing trend, in particular due to homicides among adolescents, where the coefficient increased on average 3.05 per year, yielding a relative increase of 601, 3% over the study period. In 1995, more than 90% of these homicides were perpetrated with fire weapons. These data reinforce the seriousness of this problem and the need to deal with it, taking into account the difficulties in determining the causes of violence.

[Underlying cause of death from external causes: validation of official data in Recife, Pernambuco, Brazil]. / Causa básica da morte por causas externas: validação dos dados oficiais em Recife, Pernambuco, Brasil.

OBJECTIVE: To validate the underlying cause of death recorded on the death certificates for individuals under 20 years of age who died from external causes in 1995 in Recife, Pernambuco, Brazil. METHODS: We divided the study into two stages, coding and validation. In both stages we compared the official data concerning causes of death to the data we obtained during our study. We grouped the death certificates into 5 broad categories according to the cause of death; we later subdivided them into 14 categories. We also individually compared the death certificates applying the four-digit system of the International Classification of Diseases, Ninth Revision (ICD-9). We assessed the agreement between the official data and our data in terms of sensitivity and the kappa coefficient. We took as the standard the categorization of the cause of death that we had made during our investigation. RESULTS: In the coding stage, considering all the external causes of death, the overall agreement between the official data and our study data was 94% for the 5 categories, 92% for the 14 categories, and 81% for the four-digit ICD-9 system. In the validation stage the overall agreement was 94% for the 5 categories, 91% for the 14 categories, and 73% for the four-digit ICD-9 system. CONCLUSIONS: Our results suggest that for the death certificates to be reliable, the Institute of Legal Medicine must fill them out following recommended standards. In addition, hospitals and police departments must use greater care in completing the transfer slips that accompany the bodies that are sent to the Institute. More accurate data need to be generated and disseminated for a society to better understand its patterns of violence.

[Fulfilling of variables in the declarations of external cause of death of children and adolescents in Recife from 1979 to 1995]. / Preenchimento de variáveis nas declarações de óbitos por causas externas de crianças e adolescentes no Recife, de 1979 a 1995.

This article analyzes the completion of death certificates related to external causes in children and adolescents residing in Recife, Pernambuco State, Brazil, from 1979 to 1995. The analysis focused on the extent to which the following variables were filled in: personal data (occupation, level of schooling, medical care, confirmation of diagnosis by post-mortem, and type of violence) and place (location and municipality of both occurrence and death). Using the chi-squared method, quantitative and/or qualitative flaws were found in most of the variables analyzed. In 1995, the "schooling" and "medical care" variables were recorded in only 5.7% and 17.9% of cases, respectively. Mismatches were observed between data on place of death and medical care, as well as between place of accident and number of accidents. The results suggest a dissociation between the objective of including the variable in the death certificate and its social function. The study provides the public sector with support for improved collecting and critical analysis of data in the mortality information system.

Pulmonary function response to EDTA, an additive in nebulized bronchodilators.

BACKGROUND: Some nebulized bronchodilator solutions contain additives, such as EDTA, benzalkonium chloride (BAC), or both. OBJECTIVE: Although BAC-induced bronchoconstriction has been well documented in patients with asthma, there is no information on the effects of EDTA on FEV(1) when inhaled in the amounts that would be administered during emergency department treatment of asthma. METHODS: Eighteen subjects with stable asthma and airway responsiveness to methacholine were randomly assigned to inhale up to four 600-microg nebulized doses of EDTA, BAC (positive control), and normal saline (placebo) in a double-blind crossover manner on separate days. FEV(1) was measured 15 minutes after each dose. Treatments were repeated every 20 minutes until FEV(1) decreased by 20% or greater or a maximum of 4 doses were administered. RESULTS: Mean +/- SD maximum percent decrease in FEV(1) was 1.8% +/- 5.8% after EDTA, 16.6% +/- 13.9% after BAC, and 3.6% +/- 8.2% after placebo (P <.001); there was no significant difference between EDTA and placebo. CONCLUSION: The amount of EDTA contained in maximum recommended doses of nebulized bronchodilators does not induce bronchospasm. In contrast, BAC induces clinically important bronchospasm, which could decrease the efficacy of a bronchodilator during an emergency.

[Risk factors, clinical and laboratory aspects of asthma in children] / Fatores de risco, aspectos clínicos e laboratoriais da asma em crianças.

OBJECTIVE: To evaluate the clinical and laboratory aspects and the risk factors associated with asthma in children treated at the Pediatric Outpatient Clinic of Hospital Universitário Júlio Müller. METHODS: A case-control study including 59 asthmatic children (cases) and 104 nonasthmatic children (controls). The following factors were considered for risk analysis: parents level of education, domestic exposure to allergens, passive smoking, breast feeding, low income, and family history of allergy. Samples of blood were collected for hemogram and to determine the total serum IgE as well as the one specific to allergens. Immediate hypersensitivity skin tests were performed with puncture for the detection of the following allergens: house dust mite, animals, molds, and cockroaches with positive (histamine) and negative controls (physiologic solution). A logistic regression model was used to calculate the odds ratio (OR) and 95% confidence intervals (95%CI) adjusted for risk factors and for confounding factors. RESULTS: Among the risk factors studied, sex, parents low level of education, low income, length of the breast feeding period, and passive smoking were not associated with the presence of asthma. The domestic exposure to allergens was similar in both groups except for the higher frequency of pets at the homes of control patients (chi-square=16.9; P<0.05). Paternal history of rhinitis was the only association with asthma (OR=3.33; 95%CI: 1.03-11.17; P<0.05). The asthmatic children presented higher frequency of positive reactions to skin tests than the controls, mainly to house dust mites: Dermatophagoides pteronyssinus (69.5%), Dermatophagoides farinae (59.3%) and Blomia tropicalis (59.3%); cockroaches: Periplaneta americana (59.3%), and cat: Felis domesticus (37.3%), with OR between 11.2-21.0; P<0.05. Eosinophilia and serum levels of total IgE were more elevated in the group of asthmatic children (P<0.05). The positivity of the specific IgE test for Dermatophagoides pteronyssinus and Blomia tropicalis was higher in the cases than in the controls (P<0.05). The multivariate analysis showed that sensitization to the allergens produced by cockroaches (OR=9.26; 95%CI: 2.59-33.4), animals (OR=3.93; 95%CI: 1.05-14.67) and house dust mites (OR=3.74; 95%CI: 1.18-11.8) were the most important risk factors for asthma. CONCLUSIONS: The sensitization to indoor allergens, mainly to house dust mites, cockroaches, and cats showed a strong association with asthma in this study.

Ocular-specific delivery of timolol by sequential bioactivation of its oxime and methoxime analogs.

S-(-)- Timolol maleate was oxidized, using the modified Pfitzner-Mofatt method, to the corresponding keto analog, which was then coupled with either hydroxylamine or methoxyamine in the same reaction medium. The products separated, timolone oxime (TO) or timolone methoxime (TMO), were found to be a mixture of both E and Z isomers with the Z isomer in higher concentration. Both isomers could be separated on silica column. No isomerization of any of the isomers could be detected whether in buffers or biological fluids. TMO salts were found to be stable in slightly acidic buffer. The Z isomer of TMO is more stable than the E isomer. Both TO and TMO showed pronounced reduction of the intraocular pressure (IOP) in normotensive rabbits, when instilled into the conjunctival sac. Reduction of IOP caused by either TO or TMO was higher than the reduction produced with the same dose of timolol maleate. Equal doses of any of the TMO isomers or the mixture of isomers gave almost the same percent reduction of IOP. TMO and TO did not show cardiovascular effects when administered intravenously to rabbits or rats. Both are good candidates to be used for topical management of glaucoma without producing systemic side effects.

Ocular-specific chemical delivery systems of betaxolol for safe local treatment of glaucoma.

Novel ketomethoxime (BMO) and oxime (BO) analogs of betaxolol (B) were prepared through the oxidation of betaxolol, followed by quenching of the ketone with the appropriate oxyamine. The Z isomers were kinetically favored and thermodynamically more stable. Isomerization to reach an equilibrium mixture of Z/E was observed for all pure isomers in buffers. Equilibration is much faster, however in biological fluids. Ocular administration of any of the oxime derivatives, delivers betaxolol specifically to the eye tissues, with the highest concentration in the iris ciliary body. Both BMO and BO, when applied topically, showed marked reduction of intraocular pressure (IOP) in normotensive rabbits. No effect on isoproterenol-induced tachycardia in rabbits and rats were observed, even after iv. administration. Very mild eye irritation, which was less than that of betaxolol hydrochloride, was observed particularly with BMO maleate, which is an excellent candidate for safe treatment of glaucoma.

Mutational analysis of a plant heat shock element.

A total of 32 mutations were generated within the TATA-proximal site 1 (-72 to -47) of soybean heat shock gene Gmhsp17.5E in order to functionally define the optimal configuration of sequences within the heat shock element (HSE). Mutants were tested in vivo utilizing sunflower tumors transformed by a T-DNA based vector. Promoter activity was determined by S1 nuclease hybrid protection analysis of tumor transcripts. A total of five repeats (5'-nGAAn-3' or 5'-nTTCn-3') which comprise the HSE at site 1 were required for full transcription induction by heat stress. Analysis of non-conserved bases flanking the central trinucleotide block indicated that 5'-aGAAg'-3' is the optimum sequence for the 5 bp repeat.

Anemia em pessoas da cidade de Cáceres/MT e suas relaçöes com renda per capita / Anemia in inhabitants of Cáceres/MT and its relation with income per capita

Foram estudadas a anemia e suas relaçöes com a renda per capita em 1178 pessoas na cidade de Cáceres, Mato Grosso, Brasil nas faixas etárias de 6 a 14 anos (ambos os sexos), 15 a 45 anos do sexo feminino e 15 a 45 anos do sexo masculino. Encontrou-se maior prevalência de pessoas anêmicas nas faixas de renda < 1/4 do salário mínimo e 1/4 - 1/2 do salário mínimo nas três faixas etárias estudadas. Observou-se associaçäo estatística entre a renda per capita e as médias de hemoglobina para as três faixas etárias

Study of colostrum of a patient with selective IgA deficiency.

In a study of immunological factors in colostrum, we detected an 18-year old primipara with selective IgA deficiency and with a history of 3 previous hospitalizations for bronchopneumonia. Peripheral blood studies showed: IgG = 1240 mg%; IgM = 160 mg, and undetectable IgA on two different occasions. B lymphocyte measurement by immunofluorescence for membrane immunoglobulins, T lymphocyte determination by rosette formation with sheep red cells, and T lymphocyte determination with monoclonal antibodies of the Ortho series showed normal results. Salivary IgA was undetectable. The colostrum results were: undetectable IgA (mean, 19.2 g/l); IgM, 22,2 g/l (mean, 2.3 g/l); IgG, 1.3 g/l (mean, 0.7 g/l), and lysozyme, 214.2 mu/ml (mean, 157.1 mu/ml). The very high IgM levels detected in the colostrum of these patients are interpreted to be a compensatory factor for the lack of IgA.