OBJECTIVEThe super-high-molecular-weight poly-DL-lactic acid (PDLLA), with the molecular weight of 900 kD, is a newly emerging biomaterial and potentially used in the therapy of bone fracture because of its excellent mechanical property. However the biocompatibility of this material has not been reported so far, therefore this experiment was designed to examine whether the super-high-molecular-weight PDLLA was harmful to creatures, when it was implanted in the body of animals for a long period.

METHODSThe material was prepared in small cuboids, with the size of 1.0 mm x 1.5 mm x 2.0 mm, and these blocks were implanted into the masseteric space of SD rats and, the activity of the SD-rats was monitored continuously. The animals were sacrificed in the 3rd, 6th, 9th, 12th months after the operation and, the specimens were taken out from the animals. The examination included anatomical, pathological and haematological methods. The data were analyzed with SPSS 8.0.

RESULTSThe wound healed well after the operation. Super-high-molecular-weight PDLLA degraded 6 months after the implantation. In the 3rd month after the operation, a thin fiber membrane around the materials was formed. In the 6th month, the membrane was much thinner than that in the 3rd month and completely disappeared in the 9th month. The pathological examination showed that slightly inflammatory reaction appeared in the tissue around these blocks in the 3rd month, but the inflammatory reactions were gradually remitted in the following 6th, 9th and 12th months. Further, the haematological examination did not show any abnormity during the 12-month observation period.

CONCLUSIONThe super-high-molecular-weight PDLLA can be degrade when it is implanted into the body of creatures, which proves its good biocompatibility.

Animals ; Biocompatible Materials ; chemistry ; metabolism ; Biodegradation, Environmental ; Bone Substitutes ; Implants, Experimental ; Lactic Acid ; chemistry ; metabolism ; Male ; Mandible ; metabolism ; surgery ; Molecular Weight ; Polyesters ; Polymers ; chemistry ; metabolism ; Rats ; Rats, Sprague-Dawley

Salmonella Typhi capsular polysaccharide vaccines were encapsulated in the Micro-particles made from polyethylene glycol-poly-DL-lactide (PELA). BALB/c mouse were divided into three groups with 20 mice in each. Mouse were immunized respectively with controlled release microencapsulated Salmonella Typhi capsular polysaccharide vaccines and Salmonella Typhi capsular polysaccharide vaccines by oral and subcutaneous administration. The mice blood and salvia were collected at the 2nd, 4th and 8th weeks respectively for the titrating of IgG and sIgA antibodies by RIA. At the 8th week, live typhoid bacteria were injected into the immunized mice for the calculation of the rate of immunization protection. The IgG titers of the controlled release microencapsulated Salmonella Typhi capsular polysaccharide vaccines group were higher than those of the other groups(P < 0.05). The IgA titers of the low groups of controlled release microencapsulated Salmonella Typhi capsular polysaccharide vaccines (oral and subcutaneous) were higher than those of the group of Salmonella Typhi capsular polysaccharide vaccines (P < 0.05). The immunization protection rates of the three groups were 40%, 100% and 60% respectively. The controlled release microencapsulated Salmonella Typhi capsular polysaccharide vaccines possess the advantages of releasing slowly in vivo and persisting long time immunogenicity.
Administration, Oral ; Animals ; Delayed-Action Preparations ; Female ; Immunoglobulin A, Secretory ; analysis ; Immunoglobulin G ; blood ; Injections, Subcutaneous ; Mice ; Mice, Inbred BALB C ; Microspheres ; Polysaccharides, Bacterial ; administration & dosage ; immunology ; Typhoid-Paratyphoid Vaccines ; administration & dosage ; immunology ; Vaccination

Objective:To explore the effect of long noncoding RNA(lncRNA)THAP7-AS1 on the glycolysis of gastric cancer(GC)cells by regulating methyltransferase-like 3(METTL3)mediated N6-methyladenosine(m6A)modification. Methods:Gene Expression Profiling Interactive Analysis(GEPIA)database was used to analyze the expression levels of THAP7-AS1 and METTL3 in GC tissues and their relationship with the overall survival of GC patients.Real-time fluorescence quantitative PCR and Western blotting were used to analyze the expression of THAP7-AS1,METTL3 mRNA,glucose transporter 1(GLUT1)mRNA,and METTL3 protein in GC tissues and paracancerous tissues samples collected from 80 GC patients in Department of Oncology,The Third Affiliated Hospital of Zunyi Medical University(the First People's Hospital of Zunyi),and the relationship between THAP7-AS1 levels and the clinicopathological characteristics of GC patients was analyzed.Real-time fluorescence quantitative PCR and Western blotting were used to verify the expression of THAP7-AS1,METTL3 mRNA,GLUT1 mRNA,and METTL3 protein in GES-1,BGC-823 and SGC-7901 cells.Lentiviral infection was used to knock-down THAP7-AS1 or overexpress METTL3 BGC-823 and SGC-7901 cells,and real-time fluorescence quantitative PCR and Western blotting were used to examine effect of different treatment on the expression of THAP7-AS1,METTL3 mRNA,GLUT1 mRNA,and METTL3 protein;colorimetry assay was used to detect the m6A modification level in the total RNA;methylated RNA immunoprecipitation(MeRIP)-quantitative PCR(qPCR)was used to detect the GLUT1 m6A modification level;glycolysis stress test kits were used to detect the extracellular acidification rate(ECAR),glucose uptake and lactate production of treated GC cells;Western blotting was used to examine the expression levels of METTL3,GLUT1,M2 type pyruvate kinase(PKM2)and lactic dehydrogenase(LDHA)proteins in treated GC cells;EdU staining,wound healing assay and Transwell invasion assay were used to evaluate the proliferation,migration and invasion of treated GC cells.Finally,a mouse model of subcutaneously transplanted GC tumor was established using nude mice,and the effect of knocking-down THAP7-AS1 was assessed by measuring the tumor volume and weight,as well as the expression levels of METTL3 and GLUT1 proteins in transplanted GC tumor tissues. Results:Analysis of the GEPIA database showed that the expression levels of THAP7-AS1 and METTL3 was higher in GC tissue than those in normal gastric tissues,and the expression levels of THAP7-AS1 and METTL3 are negatively correlated with overall survival of GC patients(P＜0.05).Compared with the paracancerous tissues(or normal gastric epithelial cells),the expression levels of THAP7-AS1,METTL3 mRNA,GLUT1 mRNA and METTL3 protein was significantly increased in GC tissues(or GC cells),and the higher the expression of THAP7-AS1,the higher the TNM stage,the lower the degree of tumor differentiation,and the easier the occurrence of microvascular infiltration and lymph node metastasis(P＜0.05).Knocking-down of THAP7-AS1 down-regulated the expression levels of METTL3 mRNA,GLUT1 mRNA and METTL3 protein,the m6A modification levels in total RNA and GLUT1,the ECAR levels,the glucose uptake,the lactate production,EdU positive rate,scratch healing rate,the number of invaded cells,and the expression levels of glycolysis-related proteins(METTL3,GLUT1,PKM2 and LDHA)in GC cells(P＜0.05).Overexpression of METTL3 could partially reverse these effects of THAP7-AS1 knock-down(P＜0.05).In vivo experiments showed that THAP7-AS1 knock-down can obviously inhibit the growth of transplanted GC tumors(P＜0.05). Conclusion:lncRNA THAP7-AS1 can promote the glycolysis which further promotes the proliferation,migration and invasion of GC cells by regulating METTL3 mediated m6A modification.