Effect of incorporation of polyethylene and glass fiber on the microleakage of silorane-based and methacrylate-based composites in class II restorations: an in vitro study

Microleakage is one of the most important problems in composite restorations. One way to reduce the microleakage is decreasing the total amount of resin by insertion of fibers in composite restorations. This study aimed to compare the microleakage of Silorane and methacrylate-based composites [a nanohybrid] in Class II restorations with gingival margins on the root surface, with or without placing glass and polyethylene fiber.60 extracted sound third mandibular molars were disinfected. Class II slot cavities were provided on both proximal sides of each tooth. Based on application of composites and fibers, the teeth were randomly divided into 6 groups [n=20]. group1: Z350; group2: Z350 + polyethylene fiber; group3: Z350 + glass fiber; group4: P90; group5: P90 + polyethylene fiber; and group6: P90 + glass fiber. The specimens were thermocycled, immersed in 2% basic fuchsine dye solution, and then sectioned to assess dye penetration under stereomicroscope [40X]. Results were statically analyzed by Kruskal-Wallis and Mann-Witney tests at a significance level of p<0.05.There was a significant decrease in microleakage in Silorane composite when compared to nanohybrid composite [p<0.001]. There was not any significant difference among groups with or without fiber inserts.The use of Silorane composite reduces the microleakage in comparison with nanohybrid composite and fiber insertion had no effect on the microleakage in class II silorane and nanohybrid composite restorations with gingival margins below the CEJ

[Rapidisolation and molecular detection of streptomycin-producing streptomycetes]

Streptomyces species are mycelial, aerobic gram-positive bacteria that are isolated from soil and produce a diverse range of antibiotics. Streptomyces griseus produces the antibiotic, streptomycin and forms spores even in a liquid culture. The gene cluster for the production of Streptomycin antibiotic contains strR gene that encodes StrR, a pathway-specific regulator. Then, this pathway-specific regulator induces transcription of other streptomycin production genes in the gene cluster. The overall aim of this work was rapid isolation and molecular detection of streptomycin-producing Streptomycetes, especially S. griseus, from Iranian soils in order to manipulate them for increased production of streptomycin. This research used new initiative half-specific medium for isolation of Streptomycetes from natural environments, called FZmsn. The fifty colonies of Streptomyces strains grown on the surface of FZmsn medium isolated from environmental samples were defined on the basis of their morphological characteristics and light microscope studies. A set of primers was designed to detect strR by OLIGO software. In colony-PCR reactions followed by gel electrophoresis, 6 colonies from Streptomyces strains colonies were detected as S. griseus colonies. These native Streptomyces strains will be used for genetic manipulation of S. griseus in order to increase production levels of streptomycin

Dietary overlap between invasion ctenophora [M . leidyi ] and anchovy [C. engrauliformis] in the southern parts of Caspian Sea

Mnemiopsis leidyi, native to America, Invaded the Caspian Sea in 1999. By the end of 2000, the entire sea was accupied with them. In parallel, a sharp decline in pelagic fish such accurrred. This survey was studied the relationship between the M. leidyi and this decline. Dietary analysis was conducted on anchovy sprat [Clupeonnela engrauliformis] and M. leidyi from August 2001 to October 2002 in the coastal water in the southern parts of Caspian Sea, in Iran. M. leidyi was caught by plankton net, [the mesh size -5 mm], at three depth at 5, 10 and 15 m. Sprat was caught by fisheries boat at Babolasar fishery harbor. Samples were not fixed in M. leidyi common fixative, 96% Ethanol were used. The Schoener index analysis reflected a similar diet composition of both species, with an critical level of overlap [>89 in Babolsar samples and >84 in Noushahar samples]. This competition is one of the reasons for the decline of anchovy sprat. also, the results show M. leidyi is feeding on fish eggs, but effects of this factor on anchovy population is less than feeding competition. Controlling of M. leidyi population is reducing the pressure of its invasion and the effective approach is introduces a predator to the Caspian Sea