effect of finishing and polishing time on microleakage of composite restorations

Composite resins require time to complete their polymerization. This process usually reaches its maximum rate after 24 hours. On the other hand, immediately after restoration, water sorption results in hygroscopic expansion of composite resins and the mentioned two factors usually reachequilibrium after a week. Considering the effect of mentioned processes on the microleakage of composite restorations, the purpose of the present study was to evaluate the effect of finishing and polishing time on the mean microleakage of composite restorations. In this in-vitro experimental study, 60 sound human premolar teeth were selected. A standard Class V cavity was prepared measuring 1.5 mm in depth, 3 mm in width and 2 mm in length on the buccal surface of each tooth and incrementally restored with composite resin. Next, the teeth were randomly divided into 4 groups. The teeth in groups 1, 2, 3 and 4 were finished and polished immediately, 15 min, 24 h and one week after storage in distilled water at 37°C, respectively. Specimens in each group were subjected to 500 thermal cycles. The teeth were then coated with adhesive wax and nail varnish and immersed in 2% fuchsin solution for 24h. The specimens were washed and each sample was longitudinally sectioned in half by a diamond saw. Both halves were evaluated in terms of dye penetration under a stereomicroscope at 28X magnification. For each sample, the section with greater degree of microleakage was selected. Kruskal Wallis test and Mann Whitney U test were used for data analysis with a 99.1% confidence interval. The lowest mean microleakage was observed in the occlusal margin of group 3 teeth; while the highest mean microleakage belonged to the occlusal and gingival margins of teeth in group 2. A significant difference was noted between the 4 groups in occlusal margin microleakage [P<0.009]. However, no such difference was found in gingival margin. This study showed that the finishing and polishing timewas effective on the mean microleakage in the enamel margin of composite restorations. The best time of finishing and polishing was 24h after the restoration. Time of finishing and polishing had no effect on microleakage in dentin margins of restorations. Key words: Composite resins, polishing, microleakage

[Expression of recombinant Hc domain of Clostridium botulinum neurotoxin A in E. coli and its purification as a vaccine candidate against botulism]

Botulism is a lethal disease which is caused by the one of the neurotoxins of the 7 types of Clostridium botulinum. The carboxylic domain of the heavy chain of Clostridium botulinum bype A neurotoxin [BoNT/A-Hc], is highly capable of activating immune system and is used for production of a vaccine against botulism. The aim of this study was to express and produce soluble form of BoNT/A-Hc in recombinant E.coli. Hc part of BoNT/A was subcloned in pET28a vector and clone was expressed in E.coli BL21 [DE3]. Then the best recombinant clones were selected based on three main factors: expression, growth and plasmid stability. Then protein expression was evaluated in LB and M9 media and the protein was purified by resin column chromatography. In flask culture, under optimal conditions of bacterial culture yielded 52mg of BoNT/A-Hc soluble protein from each liter of culture medium. According to the results of this study, selection of suitable strains on the basis of important growth indices of the bacteria, expression of recombinant protein and plasmid stability can lead to in increased efficiency of the recombinant protein production

Effects of Fig tree [Ficus carica] leaf extracts on serum and liver cholesterol levels in hyperlipidemic rats

The effects of three Ficus carica leaf extracts on the total cholesterol levels [TC] of serum and liver were investigated in experimentally-induced nutritional hyperlipidemic rats. In nine treatment groups [n=5 each group], hyperlipidemic rats were treated daily with hydromethanolic [total] extract [2.5, 5, 10 mg/kg, intraperitoneal [ip]] and its aqueous fractions, namely fraction A [10, 50,250 mg/kg, ip] and fraction B [10, 50,250 mg/kg, ip] for eight days. In negative and positive control groups, animals received normal and hyperlipidemic diets with ip injections of normal saline, respectively. The lipid-lowering effect of total extract on liver cholesterol was more pronounced than that of serum. Fraction A caused a significant dose-dependent decrease in cholesterol levels in both the serum and the liver [p<0.05]. Fraction A at dosages of 10, 50 and 250 mg/kg lowered the TC in serum from 1.40 +/- 0.26 mmol/L [mean +/- standard deviation; untreated hyperlipidemic group] to 1.06 +/- 0.14, 1.04 +/- 0.07 and 0.90 +/- 0.08 mmol/L, respectively. At 50 and 250 mg/kg, it lowered the TC in liver significantly from 59.86 +/- 10.35 mg/g [untreated] to 42.61 +/- 12.08 and 37.16 +/- 5.59 mg/g, respectively. Fraction B lowered the level of TC in the serum and liver, but the results of this treatment were conflicting. Phytochemical screening showed that total extract had moderate levels of flavonoids and a large amount of tannins, which may account for the observed effects on decreasing TC levels. In conclusion, Ficus carica leaf extracts have been shown to decrease liver and serum TC levels in hyperlipidemic rats

Study of the correlation between transcutaneous bilirubin levels [Jh20-1 bilirubinometer] and serum bilirubin levels [laboratory]

Hyperbilirubinemia is a common benign problem in neonates. Nonetheless, if untreated, severe hyperbilirubinemia is potentially neurotoxic. The standard method for diagnosis of hyperbilirubinemia is determination of serum bilirubin levels in the laboratory that requires a blood sample which is both painful and stressful for neonates and entails cost and time. The objective of this study was to study the correlation between transcutaneous bilirubin levels [JH 20-1 bilirobinometer] and serum bilirubin levels. This prospective study was done on 100 jaundiced newborn term infants from March to October, 2006. Initial clinical assessment of jaundice was carried out by a physician [researcher] and simultaneously, blood sample was collected and a JH20-1 bilirubinometer was applied at two sites; forehead and sternum. The study group consisted of 57 boys and 43 girls diagnosed as jaundiced neonates. The mean serum bilirubin and mean transcutaneous bilirubin levels at forehead and sternum were 13.35, 12.95 and 12.46 mg/dl, respectively. The correlation coefficient of bilirubin levels estimated by the bilirubinometer at the forehead and sternum and serum levels were 0.773 and 0.731, respectively. At bilirubin levels higher than 12 mg/dl [cut off point], the bilirubinometer had a decreased sensitivity, but an increased specificity. Transcutaneous bilirubin measurements using JH20-1 bilirubinimeter correlate well with total serum bilirubin levels, but when bilirubin levels are higher than 12mg/dl, sensitivity of the device is reduced and therefore not reliable

Valproate-risperidone versus valproate-lithium combination in acute mania

We evaluated the efficacy of valproate plus risperidone versus valproate plus lithium combination in the treatment of acute mania. In 2-week, randomized, double-blind, parallel group study, 46 acute manic patients according to DSM-IV criteria were randomly assigned to receive combination of valproate 20 mg/ kg/day plus risperidone 2-4 mg/day [n=23] or lithium600-1200 mg/day [n=23]. The assessment of efficacy measures were according to Young Mania Rating Scale [YMRS] and Clinical Global Impressions-Severity [CGI-S] and Improvement [CGI-I] scale. Other effectiveness measures included YMRS response [YMRS reduction >50%] and YMRS remission [YMRS total scores