Synchrotron radiation-based micro-computed tomographic analysis of apical transportation of different Nickel–Titanium rotary systems in curved root canals An in vitro study

Background: In the last few decades, the availability of synchrotron sources has initiated revolutionary advances in X-ray imaging. Aims: The study aimed to evaluate the incidence of apical transportation after root canal preparation with ProTaper Gold (PTG), Hyflex electro discharge machining (HEDM), Reciproc (RPC), and WaveOne Gold (WOG) using synchrotron radiation-based micro-computed tomographic (SR–?CT) analysis. Materials and Methods: Forty mandibular molars were assigned to four experimental groups (n = 10) according to the file system used for the root canal preparation: Group 1: PTG (25/0.08), Group 2: HEDM (25/0.08), Group 3: RPC (25/0.08), and Group 4: WOG (25/0.07). The specimens were scanned on SR–?CT system before and after the root canal preparation. Apical transportation was assessed at 1, 2, 3, 4, and 5 mm section. Statistical Analysis: Two-way analysis of variance and Wilcoxon Mann–Whitney test was used. Results: No significant difference was found between the groups. Transportation in the mesial direction was of greater magnitude than distal transportation for all the files systems. Conclusion: SR–?CT can be used as a reliable diagnostic tool for further implications.

Demineralization of tooth enamel following radiation therapy; An in vitro microstructure and microhardness analysis

Objective: The objective of this study is to evaluate the effects of radiotherapy doses on mineral density and percentage mineral volume of human permanent tooth enamel. Materials and Methods: Synchrotron radiation Xray microcomputed tomography (SRμCT) and microhardness testing were carried out on 8 and 20 tooth samples, respectively. Enamel mineral density was derived from SRμCT technique using ImageJ software. Microhardness samples were subjected to Vickers indentations followed by calculation of microhardness and percentage mineral volume values using respective mathematical measures. Data were analyzed using paired t-test at a significance level of 5%. Qualitative analysis of the enamel microstructure was done with two-dimensional projection images and scanned electron micrographs using μCT and field emission scanning electron microscopy, respectively. Results: Vickers microhardness and SRμCT techniques showed a decrease in microhardness and an increase in mineral density, respectively, in postirradiated samples. These changes were related to mineral density variation and alteration of hydroxyapatite crystal lattice in enamel surface. Enamel microstructure showed key features such as microporosities and loss of smooth homogeneous surface. These indicate tribological loss and delamination of enamel which might lead to radiation caries. Conclusions: Tooth surface loss might be a major contributing factor for radiation caries in head-and-neck cancer patients prescribed to radiotherapy. Such direct effects of radiotherapy cause enamel abrasion, delamination, and damage to the dentinoenamel junction. Suitable measures should, therefore, be worked out to protect nontarget oral tissues such as teeth while delivering effective dosages to target regions

Apolipoprotein modifying effects of statins and fibrate in various age groups of coronary artery disease patients.

These days apolipoproteins especially apo B and apo A I are thought to be better predictors of risk of coronary artery disease as compared to lipids and lipoprotein cholesterol. Lifestyle modification and use of lipid modifying drugs such as statins and fibrates have proven effective in reducing the risk of coronary artery disease. Statins and fibrates are known to possess anti-atherosclerotic properties in addition to lipid modifying effects. Extensive data is available regarding lipid modification especially lowering of low density lipoprotein-cholesterol levels by these drugs. But the data regarding the effect of statins and fibrates, on apolipoprotein levels is scanty. Hence the present study was aimed at assessing the effect of statins (atorvastatin, simvastatin) and fenofibrate on serum apo B and apo A I levels in addition to their lipid modifying effects in various age groups of coronary artery disease patients. One hundred patients suffering from coronary artery disease were randomly assigned to 10 mg atorvastatin, 10 mg simvastatin and 200 mg fenofibrate, separately (without any combination). All the patients were divided into three age groups; group I (35-45 years), group II (46-55 years) and group III (> 55 years). Significant modification was observed in lipid and lipoprotein profile of coronary artery disease patients when treated with these drugs (statins and fibrates). A significant increase in serum apo A I (p < 0.01) and decline in serum apo B levels (p < 0.01) was observed in case of coronary artery disease patients after 16 weeks treatment, though the effect started after 1 month. All the three drugs reduced serum apo B levels in a comparable manner. Fenofibrate increased serum high density lipoprotein-cholesterol and apo A I levels more as compared to statins. It had nearly, proportionate effect in increasing high density lipoprotein-cholesterol and apo A I levels and reducing serum low density lipoprotein-cholesterol and apo B levels while the effect was disproportionate in case of atorvastatin and simvastatin. All the three drugs not only corrected lipid and lipoprotein cholesterol levels but also modified, apolipoprotein levels in a positive direction in coronary artery disease patients. Advancing age had no appreciable effect on the efficacy of these drugs.

Isolation of 4-aminopyridine resistant mutants affecting alkali-insoluble glucan content of cell walls in Saccharomyces cerevisiae.

Saccharomyces cerevisiae cells when grown on synthetic medium plates containing 10 mM of 4-aminopyridine (4-AP) undergo cell lysis. Using an ethylmethane sulfonate mutagenesis (EMS) screen, 4-AP resistant mutants (apr) were isolated which could grow on inhibitory concentration of 4-AP. Eighty mutants were obtained that were recessive, monogenic and formed two complementation groups. To identify genes, whose products might be interacting with the apr loci, extragenic suppressors were isolated, which reverted 4-AP resistance phenotype of apr mutants. The suppressors, when genetically characterized, were found to be recessive and represented two loci with overlapping functions. Representative alleles from apr mutants were analyzed for cell wall composition. They were found to have a higher amount of alkali-insoluble glucan signifying the role of alkali-insoluble glucan in cell wall maintenance.

Demostracion de un efecto espiroqueticida de los productos quimicos anticonceptivos sobre Treponema pallidum. / Demonstration of spirocheticial effect of chemical contraceptives on Treponema pallidum

Se ensayaron cinco productos anticonceptivos para uso intravaginal y una preparacion germicida vaginal para determinar su efecto en Treponema pallidum. Los resultados hacen pensar que posiblemente esos productos podrian ser de utilidad para prevenir la transmision de la sifilis de persona a persona

Embryonic control of isocitrate lyase activity in cotyledons of germinating soybean.

The activity of isocitrate lyase (EC 4.1.3.1) in the cotyledons of germinating soybean is controlled by the embryonic axis. Plant growth regulators like gibberellic acid, indole acetic acid and 2,4 dichlorophenoxy acetic acid are able to increase the enzyme activity in cotyledons of whole seedlings but not in dissected cotyledons. The control of induction of the enzyme activity during germination by the embryo could be mediated by the elaboration of kinetin.