Hybrid layer width after conventional diamond, carbide and ultra-sound CVD burs.

OBJECTIVES: The aim of the present study was to evaluate hybrid layer thickness of primary molars sectioned with diamond, carbide and ultrasonic CVD burs. STUDY DESIGN: The occlusal enamel surfaces often molars were removed and superficial dentin was exposed. Three standardized cavities were prepared at mesial, central and distal exposed dentin with diamond, carbide and ultrasonic CVD burs, respectively. A self-etching adhesive system (Adhese, Ivoclar/Vivadent) was applied to prepared cavities and composite resin Z100 (3M/ESPE) was inserted according to manufacturers'instructions to hybridized dentin. Samples were light-cured and the crown was sectioned mesio-distally dividing the restored cavities in two halves which were observed under scanning electron microscopy (SEM), in order to quantitatively evaluate hybrid layer thickness (microm). Three repeated measures were performed at mesial, central and distal sites and mean values obtained were submitted to one-way analysis of variance (ANOVA). RESULTS: Data (mean +/- sd) obtained were (microm): 2.69 (0.44), 3.38 (1.23) and 2.72 (1.18)for diamond, carbide and CVD burs, respectively. No differences were observed among groups (p > 0.05). The adhesive systems promoted mechanical retention, uniform and continuous hybrid layer and resin tags formation at all dentin sites for all instruments tested. CONCLUSION: The results suggest that the minimally invasive cavities prepared with diamond, carbide and CVD for ultrasound, promoted hybrid layer formation with a similar thickness regardless the bur used.

Regulation of the activation of the Fanconi anemia pathway by the p21 cyclin-dependent kinase inhibitor.

Fanconi anemia (FA) is a rare disease characterized by congenital defects, progressive bone marrow failure and heightened cancer susceptibility. The FA proteins, BRCA1 and FANCD1/BRCA2 function cooperatively in the FA-BRCA pathway to repair damaged DNA. Activation of the FA-BRCA pathway occurs via the monoubiquitination of the FANCD2 and FANCI proteins, targeting these proteins to discrete nuclear foci where they function in DNA repair. The cellular regulation of FANCD2/I monoubiquitination, however, remains poorly understood. In this study, we have examined the roles of the p53 tumor suppressor protein, as well as its downstream target, the p21(Cip1/Waf1) cyclin-dependent kinase inhibitor, in the regulation of the activation of the FA-BRCA pathway. We demonstrate that, in contrast to p53, p21 has a major role in the regulation of the activation of the FA-BRCA pathway: p21 promotes S-phase and DNA damage-inducible FANCD2/I monoubiquitination and nuclear foci formation. Several lines of evidence establish that this effect is not a consequence of a defective G1-S checkpoint or altered cell-cycle progression in the absence of p21. Instead, we demonstrate that p21 is required for the transcriptional repression of the USP1 deubiquitinating enzyme upon exposure to DNA-damaging agents. In the absence of p21, persistent USP1 expression precludes the DNA damage-inducible accumulation of monoubiquitinated FANCD2 and FANCI. Consequently, p21(-/-) cells exhibit increased levels of mitomycin C-inducible complex chromosomal aberrations and elevated γH2AX nuclear foci formation. Our results demonstrate that p21 has a critical role in the regulation of the activation of the FA-BRCA pathway and suggest a broader role for p21 in the orchestration of DNA repair processes following exposure to DNA crosslinking agents.

Streptococcus mutans biofilm adhesion on composite resin surfaces after different finishing and polishing techniques.

This study evaluated Streptococcus mutans biofilm adhesion on the surface of three composite resins (nanofilled, Filtek Z350, 3M ESPE, Salt Lake City, UT, USA; nanohybrid, Vit-1-escence, Ultradent Products, South Jordan, UT, USA; and microhybrid, Esthet X, Dentsply, Milford, DE, USA) following different finishing and polishing techniques. Sixty standardized samples (6 × 3 mm) of each composite were produced and randomly divided into three finishing and polishing treatments (n=20): 1) control group: composite resin surface in contact with Mylar matrix strips with no finishing or polishing performed, 2) Sof-Lex aluminum oxide disc technique (3M ESPE, and 3) carbide bur finishing and Astrobrush polishing technique (Ultradent). Half the samples of each group were incubated in human saliva for 1 hour, and all the samples were subjected to S mutans (ATCC 35688) biofilm development. The mean log of CFU/mL present in the S mutans biofilm was calculated, and data were statistically analyzed by three-way analysis of variance and the Tukey test (p<0.05). Human saliva incubation promoted a significant increase of bacterial adherence on all three of the composites' surfaces, regardless of the polishing treatment performed (p<0.05). Of the three, the nanofilled composite (Filtek Z350) had the lowest bacterial adherence with each of the finishing and polishing techniques despite the presence or absence of human saliva (p<0.05). Mylar matrix strips (control group) promoted the lowest bacterial adhesion on the surface of the microhybrid and nanofilled composites in the absence of human saliva.

Phenotype analysis of lymphocytes of workers with chronic benzene poisoning.

Lifetime exposure to benzene is associated to a variety of blood disorders, and except for the risk of cancer, almost nothing is known concerning health impairment in individuals who are no longer exposed. In Brazil, this exposure is one of the serious problems in workplaces, and many workers have been laid off their jobs due to this intoxication, particularly in the State of Bahia, the largest producer of benzene in Latin America, which is the area of this study. From a larger study to describe health effects and genetic polymorphisms among workers with chronic benzene poisoning (CBP), this previous specific investigation analyzes the association between CBP and the pattern of sub-populations of lymphocytes. The study was performed with a CBP group (n=24) and a control group with other occupational diseases (n=24); both were selected at the Workers Health Study Center in the State of Bahia, Brazil. Clinical and epidemiologic variables were collected from medical records and from a detailed questionnaire. The average age was similar in the two groups (51.1 and 50.7, respectively). Analyzing the mean proportions of the sub-populations of lymphocytes, statistically significant differences were found for T cytotoxic cells (TCD8) (27.9; 19.4; p=0.002) and T helper memory cell (CD4CD45RO) (31.2; 37.0; p=0.015), respectively, for the CBP group and control group. These results should be viewed with caution because of the small sample size, but they strengthen a previous impression that workers exposed to benzene have their immune system impaired, even in the long term, which may contribute to some disorders and carcinogenesis process. These workers must be strictly followed up in a medical surveillance program. Although this problem has been known for a long time, this is the first attempt to study these specific effects in Brazil.

Ethnicity and glutathione S-transferase (GSTM1/GSTT1) polymorphisms in a Brazilian population.

The distribution of polymorphisms related to glutathione S-transferases (GST) has been described in different populations, mainly for white individuals. We evaluated the distribution of GST mu (GSTM1) and theta (GSTT1) genotypes in 594 individuals, by multiplex PCR-based methods, using amplification of the exon 7 of CYP1A1 gene as an internal control. In São Paulo, 233 whites, 87 mulattos, and 137 blacks, all healthy blood-donor volunteers, were tested. In Bahia, where black and mulatto populations are more numerous, 137 subjects were evaluated. The frequency of the GSTM1 null genotype was significantly higher among whites (55.4%) than among mulattos (41.4%; P = 0.03) and blacks (32.8%; P < 0.0001) from São Paulo, or Bahian subjects in general (35.7%; P = 0.0003). There was no statistically different distribution among any non-white groups. The distribution of GSTT1 null genotype among groups did not differ significantly. The agreement between self-reported and interviewer classification of skin color in the Bahian group was low. The interviewer classification indicated a gradient of distribution of the GSTM1 null genotype from whites (55.6%) to light mulattos (40.4%), dark mulattos (32.0%) and blacks (28.6%). However, any information about race or ethnicity should be considered with caution regarding the bias introduced by different data collection techniques, specially in countries where racial admixture is intense, and ethnic definition boundaries are loose. Because homozygous deletions of GST gene might be associated with cancer risk, a better understanding of chemical metabolizing gene distribution can contribute to risk assessment of humans exposed to environmental carcinogens.

Ethnicity and glutathione S-transferase (GSTM1/GSTT1) polymorphisms in a Brazilian population

The distribution of polymorphisms related to glutathione S-transferases (GST) has been described in different populations, mainly for white individuals. We evaluated the distribution of GST mu (GSTM1) and theta (GSTT1) genotypes in 594 individuals, by multiplex PCR-based methods, using amplification of the exon 7 of CYP1A1 gene as an internal control. In São Paulo, 233 whites, 87 mulattos, and 137 blacks, all healthy blood-donor volunteers, were tested. In Bahia, where black and mulatto populations are more numerous, 137 subjects were evaluated. The frequency of the GSTM1 null genotype was significantly higher among whites (55.4 percent) than among mulattos (41.4 percent; P = 0.03) and blacks (32.8 percent; P < 0.0001) from São Paulo, or Bahian subjects in general (35.7 percent; P = 0.0003). There was no statistically different distribution among any non-white groups. The distribution of GSTT1 null genotype among groups did not differ significantly. The agreement between self-reported and interviewer classification of skin color in the Bahian group was low. The interviewer classification indicated a gradient of distribution of the GSTM1 null genotype from whites (55.6 percent) to light mulattos (40.4 percent), dark mulattos (32.0 percent) and blacks (28.6 percent). However, any information about race or ethnicity should be considered with caution regarding the bias introduced by different data collection techniques, specially in countries where racial admixture is intense, and ethnic definition boundaries are loose. Because homozygous deletions of GST gene might be associated with cancer risk, a better understanding of chemical metabolizing gene distribution can contribute to risk assessment of humans exposed to environmental carcinogens.

[Historical issues in case-control studies]. / Aspectos históricos dos estudos caso-controle.

This paper presents the main issues in the evolution of case-control studies (CCS) as of the late 1980s. The comparison of two groups regarding exposure to a risk factor has been known since the 18th century. The latter half of the 19th century witnessed a decline in the "Epidemiology of Populations", and the first CCS were only done in the 1920s. Improvement of the method occurred in the latter half of the 20th century, related to increased mortality from chronic diseases, especially in research on lung cancer and smoking. The main scientific contributions to the method were: use of the odds ratio as an estimate of relative risk; definition of statistical data analysis for retrospective studies; calculation of attributed risk and etiologic fraction; and discussion of the essence of CCS. Critics pointed to the method's possible weakness and susceptibility to bias. Application of CCS increased in the final decades of the 20th century in various areas of Epidemiology and has been considered an important tool to improve Public Health.

[Clinical and laboratorial repercussions of the nasal CPAP in preterm newborns] / Repercussões clínicas e laboratoriais do CPAP nasal em recém-nascidos pré-termo.

OBJECTIVE: Evaluate the efficacy and problems associated with nasal CPAP use. METHODS: 96 preterm newborns needing nasal CPAP either as initial ventilatory support or as weaning from the ventilator were studied prospectively. RESULTS: Nasal CPAP was used in children weighing 480g to 2,450g and corrected gestational age of 24 to 39 weeks. It was indicated in cases of apnea (12.5%), hyaline membrane disease (32.3%), pneumonia (4.2%), transient tachypnea (22%), and weaning from the ventilator (29%). The last indication was more frequent in children with lower weight (p<0.01). The median time in nasal CPAP was 60.3h. After CPAP installation, there was a significant improvement in the respiratory distress that was not shown in the blood gases analysis. The percentage of children with nasal hyperemia, nasal bleeding, abdominal distention and children that could be fed was directly proportional to how long they had been in nasal CPAP. Children weighting

Analysis of gonadotropin pulsatility in hirsute women with normal menstrual cycles and in women with polycystic ovary syndrome.

OBJECTIVE: To study the relation between plasma gonadotropin pulsatility, androgen levels, and estrogen levels in patients with polycystic ovary syndrome (PCOS), in hirsute women with normal menstrual cycles, and in healthy women. DESIGN: Prospective study. SETTING: University medical center-based cellular and molecular endocrinology laboratory. PATIENT(S): Eight healthy women (group 1), 9 hirsute women with normal menstrual cycles (group 2), and 19 women with PCOS (group 3). INTERVENTION(S): Plasma concentrations of LH and FSH were measured by RIA every 15 minutes for 12 hours. MAIN OUTCOME MEASURE(S): Rhythmic parameters of 12-hour LH and FSH secretion. RESULT(S): Rhythmic parameters of 12-hour LH secretion were significantly higher in patients with PCOS (group 3) than in controls (group 1) or in hirsute women with normal menstrual cycles (group 2). The frequency of LH pulses was statistically higher in patients with PCOS (group 3) than in controls (group 1). Statistically significant correlations were found when the frequency of LH pulses was plotted against basal LH concentrations and rhythmic parameters of 12-hour LH secretion. CONCLUSION(S): Luteinizing hormone pulse amplitude was higher in patients with PCOS than in hirsute women with normal menstrual cycles or in healthy women. The LH pulse frequency was increased only in patients with PCOS compared with healthy women and not in hirsute women with normal menstrual cycles.

Microleakage evaluation of pit and fissure sealants done with different procedures, materials, and laser after invasive technique.

This study evaluated the microleakage of pit and fissure sealants after different surface preparation (invasive technique and laser irradiation) and the use of different materials (fluoride resin-filled sealant, resin-modified glass ionomer cement and adhesive system). Eighty-four pre molars were used in this study, which were divided into seven groups. After the accomplishment of the different treatments, these were submitted to thermocycling process and assess for microleakage by examination under an epifluorescent microscope and scored zero to seven. Two specimens of each group were observed under scanning electron microscope (SEM). The results showed that laser irradiation did not lessen microleakage in pit and fissures when using a filled-resin sealant with fluoride or a resin-modified glass ionomer cement. The use of laser irradiation and adhesive system, followed by a resin-filled sealant with fluoride, showed the lowest microleakage scores in pit and fissures. Comparing this group to the resin-modified glass ionomer cement group, there was statistical significance. The use of a adhesive system decreased microleakage when using a fluoride resin-filled sealant with or without previous laser irradiation; although it was not statistically significant.

Non-Hodgkin's lymphoma risk derived from exposure to organic solvents: a review of epidemiologic studies.

The rate of non-Hodgkin's lymphomas (NHL) has increased around the world during the last decades. Apart from the role of the human immunodeficiency virus (HIV) infection in the development of NHL, exposure to chemical agents like phenoxyacetic pesticides, hair dyes, metal fumes and organic solvents are suspected to be involved. The present review evaluates the results of studies that directly or indirectly searched for an association between solvent exposure and NHL. The selected studies comprised those published from 1979 to 1997, designed to investigate risk factors for NHL, whether specifically looking for solvent exposure or for general risks in which solvent exposure could be included. In 25 of the 45 reviewed studies (55.5%), fifty-four statistically significant associations between NHL and solvent exposure related occupations or industries were reported. Statistical significance was more frequently shown in studies where solvent exposure was more accurately defined. In eighteen of such studies, 13 (72.2%) defined or suggested organic solvents as possible risk factors for NHL.

A 2-year clinical evaluation of fluoride-containing pit and fissure sealants placed with an invasive technique.

The aim of this study was to clinically evaluate fluoride-containing sealants in teeth subjected to minimal enamel reduction (preventive resin restorations). Two hundred fourteen sealants (109 FluroShield and 105 Delton Fluor) were applied in 153 teeth of 32 subjects. The sealants were evaluated for superficial irregularities, marginal adaptation, retention, and caries after 6, 12, 18, and 24 months. After 6, 12, and 18 months, the attendance at recall was 100.00%. After 24 months, 93.75% of subjects returned for reevaluation. Although total or partial loss of sealant occurred in a few instances, no occlusal caries was found in any tooth at any recall. No statistically significant differences in the results of the clinical evaluation were found between sealant in the maxillary and mandibular dentitions.