The role of silicon in plant tissue culture

Growth and morphogenesis of in vitro cultures of plant cells, tissues and organs are greatly influenced by the composition of the culture medium. Mineral nutrients are necessary for the growth and development of plants. Several morpho-physiological disorders such as hooked leaves, hyperhydricity, fasciation and shoot tip necrosis are often associated with the concentration of inorganic nutrient in the tissue culture medium. Silicon (Si) is the most abundant mineral element in the soil. The application of Si has been demonstrated to be beneficial for growth, development and yield of various plants and to alleviate various stresses including nutrient imbalance. Addition of Si to the tissue culture medium improves organogenesis, embryogenesis, growth traits, morphological, anatomical and physiological characteristics of leaves, enhances tolerance to low temperature and salinity, protects cells and against metal toxicity, prevents oxidative phenolic browning and reduces the incidence of hyperhydricity in various plants. Therefore, Si possesses considerable potential for application in a wide range of plant tissue culture studies such as cryopreservation, organogenesis, micropropagation, somatic embryogenesis and secondary metabolites production

Bioinformatics challenges in molecular epidemiology of cancers

Molecular epidemiology is the integration of molecular biologic techniques into epidemiologic study. With the advances in understanding of carcinogenesis and the human genome, there has been an evolution in the field of cancer epidemiology. However, traditional analyses of single genetic variants often fail to identify susceptibility genes for cancer risk. In particular, recent technological evolution has enabled high-throughput analyses for a number of genetic variants and driven accumulation of unprecedentedly large genome data, imposing bioinformatics challenges. These studies aim to integrate the genetic basis of complex diseases including cancers in which the interplay of multiple genetic and environmental risk factors may play an important role. Here we outline currently available approaches for detecting variants of cancer risk. We also review upcoming bioinformatics challenges and technical aspects in the field of molecular epidemiology, and discuss their future impact on the understanding of carcinogenesis and personalized strategies for cancer prevention and therapy

Biosynthesis of phenylpropanoids and their protective effect against heavy metals in nitrogen-fixing black locust (Robinia pseudoacacia)

Purpose: To examine the effect of various heavy metals (HMs) on phenylpropanoid pathway compounds in Robinia pseudoacacia.Methods: A series of pot culture experiments were performed to understand how the metabolic profile of phenylpropanoid compounds were affected by various HMs, such as redox-active HMs (AgNO3 and CuCl2), and non-redox-active HMs (HgCl2). Phenylpropanoid compound level was evaluated by high performance liquid chromatography.Results: The total phenylpropanoid level in leaves increased significantly in all the treated groups when compared to that in the untreated group (p < 0.05). However, a significant effect on the total phenylpropanoid levels was only found for redox-active HMs (p < 0.05), whereas non-redox-active HMs showed less accumulation. Chlorogenic acid and rutin were the two major phenylpropanoid compounds found after the plants were subjected to redox and non-redox-active HMs stress. However, when compared to these two compounds, the levels of catechin hydrate, epicatechin, p-coumaric acid, kaempferol, and quercetin were lower. Caffeic acid level was significantly decreased in both redox and non-redox-active HMs when compared to that in the control (p < 0.05). In addition, trans-cinnamic acid accumulation was altered based on the types and concentration of HMs.Conclusion: Phenylpropanoid metabolic pathway participated in the HM tolerance process for the protection of R. pseudoacacia from oxidative damage caused by HMs, thus allowing the species to grow in highly HMs-contaminated areas. Keywords: Heavy metals, Non-redox-active metals, Phenylpropanoid compounds, Redox-active metals, Robinia pseudoacaci

The Outcomes of Hypertransfusion in Major ABO Incompatible Allogeneic Stem Cell Transplantation

Major ABO incompatibility may be potentially associated with immediate or delayed hemolysis and delayed onset of erythropoiesis in patients receiving allogeneic hematopoietic stem cell transplantation (HSCT). To determine if hemolysis can be prevented by the inhibition of graft erythropoiesis, we performed hypertransfusion and assessed red cell transfusion requirement and independence. Between October 1995 and December 2001, 28 consecutive patients receiving major ABO incompatible HSCT at Samsung Medical Center were hypertransfused to maintain their hemoglobin levels at 15 g/dL or more. We retrospectively compared the outcomes of these patients with those of 47 patients at Asan Medical Center whose target hemoglobin levels were 10 g/dL. Reticulocyte engraftment was significantly delayed in hypertransfused group (51 days vs. 23 days; p=.001). There was no significant difference in the total amount of red cells transfused within 90 days post-HSCT (25 units vs. 26 units; p=.631). No significant difference in the time to red cell transfusion independence was observed between the two groups (63 days vs. 56 days; p=.165). In conclusion, we failed to improve red cell transfusion requirement and independence in major ABO incompatible HSCT with hypertransfusion

A Comparison of Dimensional Standard of Several Nickel-Titanium Rotary Files

Objectives The aim of this study was to compare the dimensional standard of several nickel-titanium (Ni-Ti) rotary files and verify the size conformity. Materials and Methods ProFile (Dentsply Maillefer), RaCe (FKG Dentaire), and TF file (SybronEndo) #25 with a 0.04 and 0.06 taper were investigated, with 10 in each group for a total of 60 files. Digital images of Ni-Ti files were captured under light microscope (SZX16, Olympus) at 32×. Taper and diameter at D1 to D16 of each files were calculated digitally with AnalySIS TS Materials (OLYMPUS Soft Imaging Solutions). Differences in taper, the diameter of each level (D1 to D16) at 1 mm interval from (ANSI/ADA) specification No. 101 were statistically analyzed using one-way ANOVA and Scheffe\u27s post-hoc test at 95% confidence level. Results TF was the only group not conform to the nominal taper in both tapers (p \u3c 0.05). All groups except 0.06 taper ProFile showed significant difference from the nominal diameter (p \u3c 0.05). Conclusions Actual size of Ni-Ti file, especially TF, was different from the manufacturer\u27s statements