No abstract

Highly methylated Long Interspersed Nucleotide Elements 1 (LINE-1) constitute approximately 20% of the human genome, thus serving as a surrogate marker of global genomic DNA methylation. To date, there is still lacking a consensus about the precise location in LINE-1 promoter and its methylation threshold value, making challenging the use of LINE-1 methylation as a diagnostic, prognostic markers in cancer. This study reports on a technical standardization of bisulfite-based DNA methylation analysis, which ensures the complete bisulfite conversion of repeated LINE-1 sequences, thus allowing accurate LINE-1 methylation value. In addition, the study also indicated the precise location in LINE-1 promoter of which significant variance in methylation level makes LINE-1 methylation as a potential diagnostic biomarker for lung cancer. A serial concentration of 5-50-500 ng of DNA from 275 formalin-fixed paraffin-embedded lung tissues were converted by bisulfite; methylation level of two local regions (at nucleotide position 300–368 as LINE-1.1 and 368–460 as LINE-1.2) in LINE-1 promoter was measured by real time PCR. The use of 5 ng of genomic DNA but no more allowed to detect LINE-1 hypomethylation in lung cancer tissue (14.34% versus 16.69% in non-cancerous lung diseases for LINE-1.1, p < 0.0001, and 30.28% versus 32.35% for LINE-1.2, p < 0.05). Our study thus highlighted the optimal and primordial concentration less than 5 ng of genomic DNA guarantees the complete LINE-1 bisulfite conversion, and significant variance in methylation level of the LINE-1 sequence position from 300 to 368 allowed to discriminate lung cancer from non-cancer samples.

Products containing beneficial bacteria for humans have been widely used recently. The bacteria in these products generally belong to the genus Lactobacillus. Among the species of this genus, Lactobacillus casei attracts a lot of interest due to their valuable properties. With these properties, many L.casei strains can be used as probiotics. Based on the recommendation of FAO/WHO for probiotic bacteria, in our study strain LC 304.08 was identified based on morphology and biochemical properties as well as nucleotide sequence of 16S rDNA. The strain was then evaluated for its properties in vitro such as the ability to survive at low pH and in the presence of bile salt, the ability to produce antibacterial substances and enzyme as well as its safety regarding hemolytic and antibiotic resistance. The results showed that the strain was identified as Lactobacillus casei. It survived well at low pH and in the presence of bile salt, and it produced β-galactosidase with the activity of 81 ± 1.1 (U/mL). In addition, the strain was safe regarding its hemolytic activity and antibiotic resistance.

No abstract

Lactobacillus plantarum is widely used in many fields, especially in medicine. In this study, besides thestrain’s morphology (i.e, the colony and the cell under microscrope and scan electronic microscope), antibacterial activities against some pathogenic bacteria and the nucleotide sequences encoded for bacteriocin PlnA, PlnEF and the cold shock protein (Csp) of L. plantarum UL487 isolated form Tofu (Hue) were studiedby agar diffusion method and cloning. The results showed that: i) the morphology of the colony and the cell of the strain were typical for lactic acid bacteria; ii) UL487 owned antibacterial activities against some pathogenic bacteria such as Staphylococcus aureus VTCCB 658, Bacillus cereus VTCCB 613 and Salmonella enterica VTCCB 480; and iii) the nucleotide sequences encoded for bacteriocin PlnA, PlnEF and the amino acid of the cold shock protein (Csp) of the strain were 96%, 99% and 94% identical  to those of the L. plantarum in the Gen Bank, respectively.