Polymerization behavior and thermal characteristics of two new composites at five temperatures: refrigeration to preheating

PURPOSE

Heat of composite polymerization (HP) indicates setting efficacy and temperature increase of composite in clinical procedures. The purpose of this in vitro experimental study was to evaluate the effects of 5 temperatures on HP of two new composites.

MATERIALS AND METHODS

From each material (Core Max II [CM] and King Dental [KD]), 5 groups of 5 specimens each were prepared and their total HPs (J/gr) were measured and recorded, at one of the constant temperatures 0℃, 15℃, 23℃, 37℃ and 60℃ (2 × 5 × 5 specimens) using a differential scanning calorimetry (DSC) analyzer. The data were analyzed using a two-way ANOVA, a Tukey''s test, an independent-samples t-test, and a linear regression analysis (α=0.05).

RESULTS

No polymerization reactions occurred at 0℃; then this temperature was excluded from statistical analyses. The mean HP of the remaining 20 KD specimens was 20.5 ± 14.9 J/gr, while it was 40.7 ± 12.9 J/gr for CM. The independent-samples t-test showed that there were significant differences between the HP of the two materials at the temperatures 15℃ (P=.0001), 23℃ (P=.0163), 37℃ (P=.0039), and 60℃ (P=.0106). Linear regression analysis showed statistically significant correlations between environment temperatures and HP of CM (R²=0.777).

CONCLUSION

Using CM is advantageous over conventional composite because of its better polymerization capacity. However due to its high HP, further studies should assess its temperature increase in vivo. Preheating KD is recommended. Refrigerating composites can negatively affect their polymerization potential.     

Role of corvids in epidemiology of west Nile virus in southern California

The invasion of different southern California landscapes by West Nile virus (WNV) and its subsequent amplification to epidemic levels during 2004 enabled us to study the impact of differing corvid populations in three biomes: the hot Colorado desert with few corvids (Coachella Valley), the southern San Joaquin Valley (Kern County) with large western scrub-jay but small American crow populations, and the cool maritime coast (Los Angeles) with a large clustered American crow population. Similar surveillance programs in all three areas monitored infection rates in mosquitoes, seroconversion rates in sentinel chickens, seroprevalence in wild birds, numbers of dead birds reported by the public, and the occurrence of human cases. Infection rates in Culex tarsalis Coquillett and sentinel chicken seroconversion rates were statistically similar among all three areas, indicating that highly competent mosquito hosts were capable of maintaining enzootic WNV transmission among less competent and widely distributed avian hosts, most likely house sparrows and house finches. In contrast, infection rates in Culex pipiens quinquefasciatus Say were statistically higher in Kern and Los Angeles counties with elevated corvid populations than in Coachella Valley with few corvids. Spatial analyses of dead corvids showed significant clusters near known American crow roosts in Los Angeles that were congruent with clusters of human cases. In this area, the incidence of human and Cx. p. quinquefasciatus infection was significantly greater within corvid clusters than without, indicating their importance in virus amplification and as a risk factor for human infection. In contrast the uniform dispersion by territorial western scrub-jays resulted in a high, but evenly distributed, incidence of human disease in Kern County.     

Determining hepatitis C virus genotype distribution among high-risk groups in Iran using real-time PCR

AIM:To assess hepatitis C virus(HCV)genotype patterns among high-risk Iranian groups,using real-time RT-PCR.METHODS:In this study,we evaluated the distribution of different HCV genotypes among injection drug users and other high-risk groups over a 4-year period(from 2009 to 2012)using real-time polymerase chain reaction(PCR).Sera from 888 HCV-infected patients residing in southern and southwest Iran were genotyped using real-time PCR with common primers and specific probes.These patients were grouped into distinct exposure categories.Illicit drug users constituted the primary group and were further evaluated for HCV genotype distribution and parameters such as age range.RESULTS:Of the examined HCV-infected patients,62%were substance abusers,although the route of transmission could not be determined in approximately 30%of these patients.HCV genotyping revealed that Gt1 was the most prevalent genotype among the drug users as well as among patients with thalassemia,hemophilia,solid organ recipients and those on hemodialysis.Mixed infections were only seen in addict groups,where Gt2 genotype was also found.The highest frequencies in HCV-positive addict patients were observed in the 31-40 age group.Our research also showed that the addiction age has increased,whereas the addiction rate has dropped in this region.Most illicit drug users had more than one risk factor such as tattoo and/or a history of imprisonment.CONCLUSION:This study revealed that the most common HCV-infection route and HCV-genotype in southern and southwest Iran was illicit drug abuse and Gt1,respectively.     

A study of the value of trabecular bone score in fracture risk assessment of postmenopausal women

Objective

Trabecular Bone Score (TBS) is an index of bone microarchitecture that provides additional skeletal information to areal Bone Mineral Density (aBMD). Recently TBS data has been used to optimize the Fracture Risk Assessment Tool (FRAX) predictive value. The aim of this study was to evaluate the clinical value of TBS on FRAX algorithm.

Final oocyte maturation with a dual trigger compared to human chorionic gonadotropin trigger in antagonist co-treated cycles: A randomized clinical trial

Objective

This clinical trial compared the effect of a dual trigger treatment (combination of gonadotropin-releasing hormone (GnRH) agonist and human chorionic gonadotropin (hCG) and hCG alone on oocyte quality and metaphase II oocytes’ number.

Interleukin-6 Genetic Variation and Susceptibility to Gastric Cancer in an Iranian Population

Background: Despite recent decrease in the incidence of gastric cancer, it is still a common type of cancer in the north of Iran. Many evaluations have shown that polymorphisms of cytokine genes like that for interleukin 6 (IL-6), which play important roles in regulation of the immune response, can increase the risk of gastric cancer. This study examined the role of the IL-6-174 gene polymorphism in susceptibility in an Iranian population. Method: Genomic DNA was extracted from peripheral whole blood of 100 patients and 361 healthy controls. Genotyping was accomplished by the sequence-specific primer-polymerase chain reaction (SSP-PCR) method and statistical analyses were carried out using Fisher’s exact test. Frequencies of the IL-6-174 G/C genotypes were determined under co-dominant, dominant, and recessive genetic models. Results: An association between the polymorphism of IL-6 -174 G/C and susceptibility to gastric cancer was observed. The frequency of G allele was higher in patients (78%) than in controls (70.5 %) (OR=1.48, 95% CI=1.01-2.20, P=0.04). Conclusions: The high G allele and G/G genotype frequency in patients compared to control subjects suggests that the IL-6 -174 G/C polymorphism may influence the susceptibility to gastric cancer. In addition, the demographic information showed that most of the subjects were male (69.0%) that gastric cancer is related to environmental factors.     

The effect of educational package on functional status and maternal self-confidence of primiparous women in postpartum period: a randomized controlled clinical trial

Objective: The aim of this study was to determine the effect of a training package on functional status and self-confidence of primiparous women in the postpartum period.

Method: This randomized controlled clinical trial was conducted on 136 primiparous women who were referred to health centers in Tabriz, Iran, for their second postpartum care (10–15 days after delivery). These women were randomly assigned to education (n=?68) and control (n?=?68) groups. The education group was provided with a face-to-face training session, three phone sessions, and a booklet. The control group received the routine postpartum care on days 1–3, 10–15 and 42–60. Participants completed the functional status and maternal self-confidence questionnaires before the interventio n and eight weeks postpartum. Independent t, chi-square and Fisher’s exact tests were used for data analysis.

Results: No statistically significant difference was observed between the two groups in terms of sociodemographic characteristics, except for infant’s gender (p?>?.05). At six weeks after the intervention and by adjusting for baseline scores and infant’s sex, mean scores of functional status (adjusted mean difference: 0.9; 95% CI: 0.8–1.03, p?p?Conclusion: This study showed that training women has a positive effect in increasing their self-confidence and improving their functional status.     

Improved diffusion imaging through SNR‐enhancing joint reconstruction

Quantitative diffusion imaging is a powerful technique for the characterization of complex tissue microarchitecture. However, long acquisition times and limited signal‐to‐noise ratio represent significant hurdles for many in vivo applications. This article presents a new approach to reduce noise while largely maintaining resolution in diffusion weighted images, using a statistical reconstruction method that takes advantage of the high level of structural correlation observed in typical datasets. Compared to existing denoising methods, the proposed method performs reconstruction directly from the measured complex k‐space data, allowing for Gaussian noise modeling and theoretical characterizations of the resolution and signal‐to‐noise ratio of the reconstructed images. In addition, the proposed method is compatible with many different models of the diffusion signal (e.g., diffusion tensor modeling and q‐space modeling). The joint reconstruction method can provide significant improvements in signal‐to‐noise ratio relative to conventional reconstruction techniques, with a relatively minor corresponding loss in image resolution. Results are shown in the context of diffusion spectrum imaging tractography and diffusion tensor imaging, illustrating the potential of this signal‐to‐noise ratio‐enhancing joint reconstruction approach for a range of different diffusion imaging experiments. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.