Hypothesis testing in an errors-in-variables model with heteroscedastic measurement errors

In many epidemiological studies it is common to resort to regression models relating incidence of a disease and its risk factors. The main goal of this paper is to consider inference on such models with error-prone observations and variances of the measurement errors changing across observations. We suppose that the observations follow a bivariate normal distribution and the measurement errors are normally distributed. Aggregate data allow the estimation of the error variances. Maximum likelihood estimates are computed numerically via the EM algorithm. Consistent estimation of the asymptotic variance of the maximum likelihood estimators is also discussed. Test statistics are proposed for testing hypotheses of interest. Further, we implement a simple graphical device that enables an assessment of the model`s goodness of fit. Results of simulations concerning the properties of the test statistics are reported. The approach is illustrated with data from the WHO MONICA Project on cardiovascular disease. Copyright (C) 2008 John Wiley & Sons, Ltd.

Implants of polyanionic collagen matrix in bone defects of ovariectomized rats

In recent years, there has been a great interest in the development of biomaterials that could be used in the repair of bone defects. Collagen matrix (CM) has the advantage that it can be modified chemically to improve its mechanical properties. The aim of the present study was to evaluate the effect of three-dimensional membranes of native or anionic (submitted to alkaline treatment for 48 or 96 h) collagen matrix on the consolidation of osteoporosis bone fractures resulting from the gonadal hormone alterations caused by ovariectomy in rats subjected to hormone replacement therapy. The animals received the implants 4 months after ovariectomy and were sacrificed 8 weeks after implantation of the membranes into 4-mm wide bone defects created in the distal third of the femur with a surgical bur. Macroscopic analysis revealed the absence of pathological alterations in the implanted areas, suggesting that the material was biocompatible. Microscopic analysis showed a lower amount of bone ingrowth in the areas receiving the native membrane compared to the bone defects filled with the anionic membranes. In ovariectomized animals receiving anionic membranes, a delay in bone regeneration was observed mainly in animals not subjected to hormone replacement therapy. We conclude that anionic membranes treated with alkaline solution for 48 and 96 h presented better results in terms of bone ingrowth.

New antimicrobial therapies used against fungi present in subgingival sites-A brief review

Although the main reservoir of Candida spp. is believed to be the buccal mucosa, these microorganisms can coaggregate with bacteria in subgingival biofilm and adhere to epithelial cells. The treatment of periodontal disease includes scaling and root planning (SR?) associated with proper oral hygiene. However, some patients may have negative responses to different therapeutic procedures, with a continuous loss of insertion, so the use of antimicrobials is needed as an adjuvant to SRP treatment. The use of a broad-spectrum antibiotic, such as tetracycline and metronidazole, as an aid in periodontal treatment has also been a factor for the development of superinfections by resistant bacteria and Candida species, even in patients with HIV. In the dental practice, the most commonly used antifungals are nystatin and fluconazole. However, the introduction of new drugs like the next generation of azoles is essential before the onset of emergent species in periodontal disease. Plants are good options for obtaining a wide variety of drugs. This alternative could benefit a large population that uses plants as a first treatment option. Plants have been used in medicine for a long time and are extensively used in folk medicine, because they represent an economic alternative, are easily accessible and are applicable to various diseases. Herein, we briefly review the literature pertaining the presence of Candida sp. in periodontal pockets, the conventional antifungal resistance and new therapies that include natural antifungal agents are reviewed. (C) 2011 Elsevier Ltd. All rights reserved.

Magnetic images of the disintegration process of tablets in the human stomach by ac biosusceptometry

Oral administration of solid dosage forms is usually preferred in drug therapy. Conventional imaging methods are essential tools to investigate the in vivo performance of these formulations. The non-invasive technique of ac biosusceptometry has been introduced as an alternative in studies focusing on gastrointestinal motility and, more recently, to evaluate the behaviour of magnetic tablets in vivo. The aim of this work was to employ a multisensor ac biosusceptometer system to obtain magnetic images of disintegration of tablets in vitro and in the human stomach. The results showed that the transition between the magnetic marker and the magnetic tracer characterized the onset of disintegration (t(50)) and occurred in a short time interval (1.1 +/- 0.4 min). The multisensor ac biosusceptometer was reliable to monitor and analyse the in vivo performance of magnetic tablets showing accuracy to quantify disintegration through the magnetic images and to characterize the profile of this process.

Analysis of biological tissues in infant chest for the development of an equivalent radiographic phantom

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genotoxicity in primary human peripheral lymphocytes after exposure to radiopacifiers in vitro

Taking into consideration that DNA damage plays an important role in carcinogenesis, the purpose of this study was to evaluate whether some radiopacifiers widely used in clinical practice are able to induce genetic damage in primary human cells in vitro. Human peripheral lymphocytes obtained from 10 healthy volunteers were exposed to barium sulphate (BaSO(4)), zirconium oxide (ZnO(2)) and bismuth oxide (Bi(2)O(3)) at final concentrations ranging from 1 to 1000 mu g/mL for 1 h at 37 degrees C. The negative control group was treated with vehicle control (phosphate buffer solution) for 1 h at 37 degrees C and the positive control group was treated with hydrogen peroxide (at 100 mu M) for 5 min on ice. Results were analyzed by the Friedman non-parametric test. The results pointed all compounds tested out did not induce DNA breakage in human peripheral lymphocytes as depicted by the mean tail moment and tail intensity in all concentrations tested. In summary, our results indicate that exposure to these radiopacifiers may not be a factor that increases the level of DNA lesions in human peripheral lymphocytes as detected by single cell gel (comet) assay.

In vitro microhardness of glass ionomer cements

This study evaluated the surface microhardness of four glass ionomer cements and a composite resin (Fuji IX, Ketac Molar, Vidrion R, Vitromolar and Z 250). Ten specimens of each glass ionomer cement with 8.0 mm diameter and 5.0 mm high dimensions were made and Vicker's microhardness measurements were taken at 1 day and 1 week after initial setting reaction. The results were analyzed using Student's T test and Tukey test (p < 0.05) and demonstrated that the values of microhardness increased after 1 week, with the exception of Fuji IX. Resin composite Z250 presented the greatest values for microhardness.

Antibacterial activity of four glass ionomer cements used in atraumatic restorative treatment

The in vitro antibacterial activity of four glass ionomer cements ( Fuji IX, Ketac Molar, Vidrion R and Vitromolar) indicated for Atraumatic Restorative Treatment ( ART) was studied against strains of bacteria involved in the development of oral diseases, Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus and Actinomyces viscosus. The agar plate diffusion test was used for the cultures, which included chlorhexidine as a positive control. The results demonstrated that all the cements evaluated presented antibacterial activity. Based on the results of this study, it can be concluded that Fuji IX and Ketac Molar presented the most effective antibacterial activity considering the ART approach.

Characterization and in vitro evaluation of bacterial cellulose membranes functionalized with osteogenic growth peptide for bone tissue engineering

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Three-Dimensional Ultrasonographic Assessment of Fetal Total Lung Volume as a Prognostic Factor in Primary Pleural Effusion

Objectives-The purpose of this study was to predict perinatal outcomes using fetal total lung volumes assessed by 3-dimensional ultrasonography (3DUS) in primary pleural effusion.Methods-Between July 2005 and July 2010, total lung volumes were prospectively estimated in fetuses with primary pleural effusion by 3DUS using virtual organ computer-aided analysis software. The first and last US examinations were considered in the analysis. The observed/expected total lung volumes were calculated. Main outcomes were perinatal death (up to 28 days of life) and respiratory morbidity (orotracheal intubation with mechanical respiratory support >48 hours).Results-Twelve of 19 fetuses (63.2%) survived. Among the survivors, 7 (58.3%) had severe respiratory morbidity. The observed/expected total lung volume at the last US examination before birth was significantly associated with perinatal death (P < .01) and respiratory morbidity (P < .01) as well as fetal hydrops (P < .01) and bilateral effusion (P = .01).Conclusions-Fetal total lung volumes may be useful for the prediction of perinatal outcomes in primary pleural effusion.

Placental Volumes Measured by 3-Dimensional Ultrasonography in Normal Pregnancies From 12 to 40 Weeks' Gestation

Objective. The purpose of this study was to construct nomograms of placental volumes according to gestational age and estimated fetal weight. Methods. From March to November 2007, placental volumes were prospectively measured by ultrasonography in 295 normal pregnancies from 12 to 40 weeks' gestation and correlated with gestational age and estimated fetal weight. Inclusion criteria were healthy women, singleton pregnancies with normal fetal morphologic characteristics on ultrasonography, and confirmed gestational age by first-trimester ultrasonography. Results. The mean placental volume ranged from 83 cm(3) at 12 weeks to 427.7 cm(3) at 40 weeks. Linear regression yielded the following formula for the expected placental volumes (ePV) according to gestational age (GA): ePV` (cm(3)) = -64.68 + 12.31 x GA (r = 0.572; P < .001). Placental volumes also varied according to estimated fetal weight (EFW), and the following mathematical equation was also obtained by linear regression: ePV = 94.19 + 0.09 x EFW (r = 0.505; P < 0.001). Conclusions. Nomograms of placental volumes according to gestational age and estimated fetal weight were constructed, generating reference values.

Magnetoresistive sensors in a new biomagnetic instrumentation for applications in gastroenterology

Anisotropic Magnetoresistive (AMR) sensors shows a new possibility to detect magnetic fields produced by magnetic particles present in the gastrointestinal (GI) tract. A system that uses excitation and detection of magnetic field was developed using AMR sensor. A magnetic flux concentrator was also studied to increase the sensitivity of AMR in this work.

Gastric motility evaluated by electrogastrography and alternating current biosusceptometry in dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Prevalence and nonrandom distribution of exonic mutations in interferon regulatory factor 6 in 307 families with Van der Woude syndrome and 37 families with popliteal pterygium syndrome

Purpose: Interferon regulatory factor 6 encodes a member of the IRF family of transcription factors. Mutations in interferon regulatory factor 6 cause Van der Woude and popliteal pterygium syndrome, two related orofacial clefting disorders. Here, we compared and contrasted the frequency and distribution of exonic Mutations in interferon regulatory factor 6 between two large geographically distinct collections of families with Van der Woude and between one collection of families with popliteal pterygium syndrome. Methods: We performed direct sequence analysis of interferon regulatory factor 6 exons oil samples from three collections, two with Van der Woude and one with popliteal pterygium syndrome. Results: We identified mutations in interferon regulatory factor 6 exons in 68% of families in both Van der Woude collections and in 97% of families with popliteal pterygium syndrome. In sum, 106 novel disease-causing variants were found. The distribution of mutations in the interferon regulatory factor 6 exons in each collection was not random; exons 3, 4, 7, and 9 accounted for 80%. In the Van der Woude collections, the mutations were evenly divided between protein truncation and missense, whereas most mutations identified in the popliteal pterygium syndrome collection were missense. Further, the missense mutations associated with popliteal pterygium syndrome were localized significantly to exon 4, at residues that are predicted to bind directly to DNA. Conclusion: The nonrandom distribution of mutations in the interferon regulatory factor 6 exons suggests a two-tier approach for efficient mutation screens for interferon regulatory factor 6. The type and distribution of mutations are consistent with the hypothesis that Van der Woude is caused by haploinsufficiency of interferon regulatory factor 6. Oil the other hand, the distribution of popliteal pterygium syndrome-associated mutations suggests a different, though not mutually exclusive, effect oil interferon regulatory factor 6 function. Genet Med 2009:11(4):241-247.

Preparation and evaluation of an experimental luting glass ionomer cement to be used in dentistry

The aim of this paper is to compare the fluoride-releasing and mechanical properties of an experimental luting glass ionomer cement, which has a modified composition and a commercial luting cement. The experimental powder was obtained by sol-gel process and then, it was used to prepare the experimental cements. The properties of cement pastes, such as setting time and working time, microhardness and diametral tensile strength were determined. Fluoride release from GICs was evaluated at time intervals of 1, 7, 14, 21 and 28 days in deionized water. Atomic force microscopy (AFM) analyses showed that the surface of the experimental cements is more homogeneous than commercial GICs. The mechanical properties and the measure of liberation of fluoride of the two cements were influenced by ratio powder:liquid and chemical composition of the precursor powders. Experimental cements released less fluoride than commercial cements. However, this liberation was more constant during the analyzed period. Thus, the results obtained in this study indicated that the composition of the experimental powder modified by the niobium can lead the formation of the polysalt matrix with good mechanical properties. In other words, we can say that experimental powder offered considerable promise for exploitation in dental field.