Chromatic stability of acrylic resins of artificial eyes submitted to accelerated aging and polishing

Esthetics and durability of materials used to fabricate artificial eyes has been an important eissue since artificial eyes are essential to restore esthetics and function, protect the remaining tissues and help with patients'' psychological therapy. However, these materials are submitted to degrading effects of environmental agents on the physical properties of the acrylic resin.

Objective

This study assessed the color stability of acrylic resins used to fabricate sclera in three basic shades (N1, N2 and N3) when subjected to accelerated aging, mechanical and chemical polishing.

Material and methods

Specimens of each resin were fabricated and submitted to mechanical and chemical polishing. Chromatic analysis was performed before and after accelerated aging through ultraviolet reflection spectrophotometry.

Results

All specimens revealed color alteration following polishing and accelerated aging. The resins presented statistically significant chromatic alteration (p<0.01) between the periods of 252 and 1008 h.

Conclusions

Both polishing methods presented no significant difference between the values of color derivatives of resins.     

Proteasome inhibitor bortezomib impairs both myelofibrosis and osteosclerosis induced by high thrombopoietin levels in mice

Primary myelofibrosis (PMF) is the most serious myeloproliferative disorder, characterized by clonal myeloproliferation associated with cytokine-mediated bone marrow stromal reaction including fibrosis and osteosclerosis. Current drug therapy remains mainly palliative. Because the NF-kappaB pathway is implicated in the abnormal release of cytokines in PMF, the proteasome inhibitor bortezomib might be a potential therapy. To test its effect, we used the lethal murine model of myelofibrosis induced by thrombopoietin (TPO) overexpression. In this TPO(high) model, the development of the disease is related to a deregulated MPL signaling, as recently described in PMF patients. We first demonstrated that bortezomib was able to inhibit TPO-induced NF-kappaB activation in vitro in murine megakaryocytes. It also inhibited NF-kappaB activation in vivo in TPO(high) mice leading to decreased IL-1alpha plasma levels. After 4 weeks of treatment, bortezomib decreased TGF-beta1 levels in marrow fluids and impaired marrow and spleen fibrosis development. After 12 weeks of treatment, bortezomib also impaired osteosclerosis development through osteoprotegerin inhibition. Moreover, this drug reduced myeloproliferation induced by high TPO level. Finally, bortezomib dramatically improved TPO(high) mouse survival (89% vs 8% at week 52). We conclude that bortezomib appears as a promising therapy for future treatment of PMF patients.     

Antiinflammatory, antioxidant and cytotoxic actions of beta-glucan-rich extract from Geastrum saccatum mushroom

The Geastrum saccatum a mushroom, native to Brazil, is produced under natural conditions in the unexplored reserve of Mata da Estrela-RN. This species has curative properties for eye infections and diseases such as asthma. The tissues of this mushroom contain carbohydrates, proteins, lipids, moisture and ashes in amounts of 42.3%, 37.05%, 9.01, 1.4% and 10.2%, respectively. An extract from this mushroom was characterized by chemical analyses and (13)C and (1)H NMR spectroscopy. It contains high amount of glucose and traces of galactose. The signal appearing at 103.5 ppm was assigned to C1 of beta-glucose. The signals observed between 20 and 40 ppm suggest the presence of a glucan-protein compound. This glucan inhibited the lipid peroxidation at the dose of 0.27 mg/mL (59.1%) and it can protect cells against oxidative stress by scavenging of the hydroxyl (77%) and superoxide (88.4%) radicals at 0.27 mg/mL. The glucan (30 mg/kg) reduces the polymorphonuclear cell migration (57.6%). The ear edema induced by croton oil was inhibited by glucan (60.4% at 10 mg/kg) and by its association with diclofenac (5 mg/kg) (89.2%) or L-NAME (60 mg/kg) (86.23%). Histological analyses of the ear edema induced by croton oil in the presence of glucan (10, 30 or 50 mg/kg) showed a reduced degree of the polymorphonuclear cell migration. We concluded that the glucan has antioxidant, and antiinflammatory properties as well as its antiinflammatory effect are mediated by inhibition of both nitric oxide synthase (NOS) and cyclooxygenase (COX).     

Using collaborative learning to improve diabetes care and outcomes: The VIDA project

The prevalence of diabetes in Mexico among those 20–64 years of age has increased from 7.2% in 1993 to 10.7% in 2000. National population-based surveys in Mexico demonstrated that 50% of the total population with diabetes had blood glucose levels of 200 mg/dl or higher. Thus, diabetes care has become one of the most important public health challenges in this country. The aim of the study was to improve the quality of diabetes care in primary health care centers using the chronic care model and the breakthrough series (BTS) collaborative methodology.MethodsTen public health centers in the cities of Xalapa and Veracruz were randomly selected to participate in the project. Five of the health centers were randomly assigned to receive the intervention (intervention group) and the other five followed usual care (usual care group). The intervention was evaluated by A1c test before and after the intervention in both groups of patients. Patients were followed for 18 months from November 2002 to May 2004. Results were adjusted for the clustering of patients within practices and baseline measure.ResultsThe proportion of people with good glycemic control (A1c < 7%) among those in the intervention group increased from 28% before the intervention to 39% after the intervention. The proportion of patients achieving three or more quality improvement goals increased from 16.6% to 69.7% (p < 0.001) among the intervention group while the usual care group experienced a non-significant decrease from 12.4% to 5.9% (p = 0.118). The focus on the primary care team and the participation of people with diabetes were strategic elements incorporated into the methodology, expected to ensure sustainability of continued improvement of health outcomes.ConclusionsThe intervention introduced modifications to solve problems identified by health teams in their practice and improved process and outcome measures of quality diabetes care. Most of the actions were directed at four components of the chronic care model: self-management support, decision support, delivery system design, and clinical information systems.     

Endoscopic treatment of vesicoureteral reflux—a 20-year follow-up

Endoscopic reflux therapy has gained more and more popularity, and the use of this method is increasing.These imaging patterns (well known by pediatric radiologists) should be known by the general radiologist as the first young patients treated 20 years ago are now adults.     

14. EXPOSURE AND EFFECT MONITORING OF WORKERS IN THE COBALT/HARD METAL INDUSTRIES: ABSENCE OF SIGNIFICANT GENOTOXIC EFFECTS

An increased lung cancer risk is associated with occupational exposure to mixtures of cobalt metal and metallic carbide particles, but when exposure is to cobalt metal alone. The current TLV-TWA was established without consideration of carcinogenicity data. The present study was designed to assess whether an increased cancer risk can be detected in workers currently exposed on average to the TLV-TWA (20 μg/m3).     

Indications for a threshold of chemically-induced aneuploidy in vitro in human lymphocytes

The possible existence of a threshold for compounds inducing chromosomal loss was investigated for four known aneugens (colchicine, COL; carben-dazim, MBC; mebendazole, MEB; nocodazole, NOC) and two clastogens (methyl methanesulfo-nate, MMS; mitomycin C, MMC) using the micronu-cleus (MN) test in human lymphocytes. The presence of a whole chromosome in the MN was studied by fluorescent in situ hybridization (FISH) using a synthetic pancentromeric oligonucleotide probe. FISH was applied on two different MN preparations: cytokinesis-blocked MN (MNCB) assay, and MN sorted by flow cytometry. At subtoxic concentrations analyzed by MNCB and FISH, COL, MEB, MBC, and NOC induced a concentration-dependent increase in centromere-positive MN (MNCen+), MMC seemed to induce an increase in both types of MN (MNCen- and MNCen+), while MMS induced only MNCen-. On the sorted micronuclei (in a wide range of low to subtoxic concentrations), the concentration-effect profile for MNCen+, with the four aneugens tested, showed a statistically nonsignificant increase over a range of concentrations, followed by a second range of high concentrations with a statistically significant increase. To analyze the existence of a threshold, a piecewise linear regression was applied to the data. The first concentration that showed a statistically significant increase in MNCen+ was chosen as a breakpoint (0.037 μM for COL, 2.62 μM for MBC, 0.27 μM for MEB, and 0.066 μM for NOC). The statistical correlation between observed and predicted values showed a high correlation (r = 0.99), indicating a clear threshold for aneuploidy induction. However, for MMS the concentration-effect profile for MNCen+ showed a continuous concentration-dependent decrease with no threshold. With the two cytotoxicity assays used (Bio-Rad and MTT), no significant reduction was detected either in the protein content or in mitochondrial succinate dehydrogenase activity with all chemicals tested for MN induction. Therefore, our data suggest that the observed thresholds were not due to indirect toxic effects but to real aneugenic effects. © 1995 Wiley-Liss, Inc.