Objective:To study the stress distribution in bone with different densities around dental implants in different shape.Methods:Dental implants in the shape of cylinder,thread and steps were implanted into the mandibular bone at the position of the first molar with 4 different densities respectively.Three-dimension finite element models were rebuilt and stress distribution in the bone around implants were investigated. Results:In the same load and bone density conditions, cylindrical implant resulted in lowest peak stress value,the same implant in mandibular bone with higher density produced lower stress peak value.Conclusion:Dental implatns in the shape of cylinder and higher density of the bone around the implant may reduce stress concentration.

Using the CT data, we have constructed the finite element models of human femur distally amputated at high-position, middle-position and low-position, along with distally osseointegrated implant under the maximal load during a normal walking cycle. Results of finite element analysis revealed: the maximal stress of implant is produced near the exit of the amputated limb, where the fatigue breakpoint caused by cyclic stress would take place. With the ascending of truncated position, the peri-implant interfacial stress of bone increases. There is severe stress-shielding at the bone-implant interface, and there is concentration of stress at the end of implant and at the 3/4 point of femur, which would lead to bone loss and bone resorption and would shorten the longevity of implant. The results also showed that the curvature of natural bone has notable effect on the stress distribution, which should not be neglected. These data may provide reliable reference for the design and research of osseointegarted artificial limb.
Artificial Limbs ; Computer Simulation ; Femur ; physiology ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Models, Biological ; Osseointegration ; physiology ; Prosthesis Design ; Stress, Mechanical

Objective:The study aims to investigate the characteristic baseline information about genetic lineages, drug-resistance genes, virulence genes and evolutionary relationships of food-borne Listeria monocytogenes (Lm) isolates from Nanshan district of Shenzhen.Methods:The whole genomes of 46 Lm isolates during 2009-2019 were extracted and sequenced (Illumina PE-150, 100×). The CLC Genomics Workbench 12.0 was used to assemble and align Lm genomes, analyze their housekeeping genes, drug-resistance genes and virulence genes, and construct a k-mer phylogenetic tree.Results:After assembly, all genomes satisfied analytical conditions (contigs N50>20 kb). The medians of GC content, gene count and gene size were 38.3%, 5 960 and 2 952 608 bp, respectively. Based on the Lm genomic reference database, the local k-mer phylogenetic tree had 14 clusters of which the genetic distance was wide. The 46 Lm isolates were classified as Lineage 1 (21), Lineage 2 (23) and Lineage 3 (2). The most common ST type of Lineage 1 was ST87, followed by ST3, ST59, ST224 and ST429, whereas the major ST types of Lineage 2 included ST8 and ST9, the rest being ST121, ST155, ST199, ST204 and ST321. However, Lineage 3 only had ST299. The part of Lm strains carried five drug-resistance genes, such as fosX (17), tetM (6), dfrG (4), catB3 (1) and mefA (1). Furthermore, all strains possessed nine virulence genes, including flaA, iap, actA, hly, mpl, prfA, plcA, plcB and inlB. Nevertheless, six isolates and three of them respectively carried the mutant inlA and inlJ, and other two isolates lacked inlC.Conclusion:The food-borne Lm isolates from Nanshan district of Shenzhen presented genetic and evolutionary diversity. Noted that the drug-resistant strains, which also owned abundant virulence genes with specific functions, could lead to serious infections, particularly those isolates from raw poultry and Flammulina velutipes. It was implied that the local region was at risk due to Listeriosis by food. This study offered reference for prevention, control and treatment of Lm infection to the Greater Bay Area.

Objective:The study aims to investigate the characteristic baseline information about genetic lineages, drug-resistance genes, virulence genes and evolutionary relationships of food-borne Listeria monocytogenes (Lm) isolates from Nanshan district of Shenzhen.Methods:The whole genomes of 46 Lm isolates during 2009-2019 were extracted and sequenced (Illumina PE-150, 100×). The CLC Genomics Workbench 12.0 was used to assemble and align Lm genomes, analyze their housekeeping genes, drug-resistance genes and virulence genes, and construct a k-mer phylogenetic tree.Results:After assembly, all genomes satisfied analytical conditions (contigs N50>20 kb). The medians of GC content, gene count and gene size were 38.3%, 5 960 and 2 952 608 bp, respectively. Based on the Lm genomic reference database, the local k-mer phylogenetic tree had 14 clusters of which the genetic distance was wide. The 46 Lm isolates were classified as Lineage 1 (21), Lineage 2 (23) and Lineage 3 (2). The most common ST type of Lineage 1 was ST87, followed by ST3, ST59, ST224 and ST429, whereas the major ST types of Lineage 2 included ST8 and ST9, the rest being ST121, ST155, ST199, ST204 and ST321. However, Lineage 3 only had ST299. The part of Lm strains carried five drug-resistance genes, such as fosX (17), tetM (6), dfrG (4), catB3 (1) and mefA (1). Furthermore, all strains possessed nine virulence genes, including flaA, iap, actA, hly, mpl, prfA, plcA, plcB and inlB. Nevertheless, six isolates and three of them respectively carried the mutant inlA and inlJ, and other two isolates lacked inlC.Conclusion:The food-borne Lm isolates from Nanshan district of Shenzhen presented genetic and evolutionary diversity. Noted that the drug-resistant strains, which also owned abundant virulence genes with specific functions, could lead to serious infections, particularly those isolates from raw poultry and Flammulina velutipes. It was implied that the local region was at risk due to Listeriosis by food. This study offered reference for prevention, control and treatment of Lm infection to the Greater Bay Area.

ObjectiveTo explore the effect of interaction of hypertension and abdominal obesity on morbidity of diabetes and to provide the scientific bases for preventing diabetes. MethodsA total of 11 914 people who took the physical examination in 2019 were examined with cluster sampling method for the interaction analysis. The data was collected by physical measurements and laboratory tests. SPSS 16.0 and interaction models were used for data analysis. ResultsIn the subjects there were 75.19% with abdominal obesity， 47.99% with hypertension， 16.26% with diabetes， and 39.42% had abdominal obesity plus hypertension. Multivariate logistic regression analysis showed， after adjusting gender and age， the abdominal obesity（OR=1.29， 95%CI：1.14‒1.46） and hypertension （OR=2.93， 95%CI： 2.63‒3.26） were related to high risk of diabetes. There was no multiplicative interaction effect between abdominal obesity and hypertension （OR=0.98，95%CI： 0.76‒1.27）. The additive interaction was significant between abdominal obesity and hypertension with RERI=0.53（95%CI：0.09‒0.98）， AP=0.14（95%CI：0.02‒0.26）， and SI=1.24（95%CI：1.01‒1.52）. ConclusionThere is a synergistic effect on morbidity of diabetes between abdominal obesity and hypertension. The improvement of weight and control of blood pressure could prevent significantly the diabetes.