Influence of pulling direction on knot security: A laboratory research.

BACKGROUND: When tying knots, some surgeons do not pay particular attention to the direction in which they pull to lay down throws. We examine to what extent does pulling direction influence on knot security. METHODS: A total of 368 residents were instructed to tie knots with from 2 to 7 throws using silk braided suture in 3-0 gauge. The direction in which they pulled to lay down throws was recorded. Only the knots tied either by pulling in alternate directions (Group A) or in constant direction (Group C) from the first throw to the last were involved in statistical analysis. Tensile strength and untying rate of the knots were then measured for comparative analysis. RESULTS: For knots with from 2 to 7 throws, the tensile strength of the ones from Group A was significantly higher than that of the ones from Group C (p < 0.05), respectively. For knots with from 5 to 7 throws, the untying rate of the ones from Group A was significantly lower than that of the ones from Group C (p < 0.05), respectively. For the unraveled knots with from 2 to 7 throws (except for the ones with 5 throws), the tensile strength of the ones from Group A was significantly higher than that of the ones from Group C (p < 0.05), respectively. CONCLUSION: Pulling in constant direction results in inferior knot security. Surgeons must ascertain the influence of pulling direction on knot security, and try to achieve superior security with fewer throws to ensure patient safety.

Pseudomonas lijiangensis sp. nov., a novel phytopathogenic bacterium isolated from black spots of tobacco.

Three Gram-stain-negative, motile, with amphilophotrichous flagella, and rod-shaped bacteria (LJ1, LJ2T and LJ3) were isolated from lower leaves with black spots on flue-cured tobacco in Yunnan, PR China. The results of phylogenetic analysis based on 16S rRNA gene sequences indicate that all the strains from tobacco were closely related to the type strains of the Pseudomonas syringae group within the P. fluorescens lineage and LJ2T has the highest sequence identities with P. cichorii DSM 50259T (99.92 %), P. capsici Pc19-1T (99.67 %) and P. ovata F51T (98.94 %) . The 16S rRNA gene sequence identities between LJ2T and other members of the genus Pseudomonas were below 98.50%. The average nucleotide identity by blast (ANIb) values between LJ2T and P. cichorii DSM 50259T, P. capsici Pc19-1T and P. ovata F51T were less than 95 %, and the in silico DNA-DNA hybridization (isDDH) values (yielded by formula 2) were less than 70 %. The major fatty acids were C16  :  1ω7c and/or C16  :  1ω6c (summed feature 3), C16  :  0 and C18  :  1ω7c and/or C18  :  1ω6c (summed feature 8). The polar lipids profile of LJ2T consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, two unidentified phospholipids and one unidentified glycolipid. The predominant respiratory quinone was Q-9. The DNA G+C content of LJ2T was 58.4 mol%. On the basis of these data, we concluded that LJ2T represents a novel species of the genus Pseudomonas, for which the name Pseudomonas lijiangensis sp. nov. is proposed. The type strain of Pseudomonas lijiangensis sp. nov. is LJ2T (=CCTCC AB 2021465T=GDMCC 1.2884T=JCM 35177T).