Covalently immobilised type I collagen facilitates osteoconduction and osseointegration of titanium coated implants.

BACKGROUND/OBJECTIVE: Plasma-sprayed titanium coating (TC) with rough surfaces has been successfully applied in hip or knee prostheses. This study aimed to investigate the osteoconduction and osseointegration of Type I collagen covalently immobilised on TC (TC-AAC) compared with those of TC. METHODS: In vitro, the migration of human mesenchymal stem cells (hMSCs) on TC and TC-AAC was observed by scanning electron microscopy and visualised fluorescent live/dead assay. In vivo, a rabbit model with femur condyle defect was employed, and implants of TC and TC-AAC were embedded into the femur condyles. RESULTS: Collagen immobilised on TC could promote hMSCs' migration into the porous structure of the TC. Micro computed tomography images showed that bone trabeculae were significantly more abundant around TC-AAC implants than around TC implants. Fluorescence micrographs indicated more active new-bone formation around implants in the TC-AAC group than in the TC group. The measurement of bone-implant contact on histological sections indicated significantly greater osteointegration around TC-AAC implants than around TC ones. CONCLUSION: Immobilised Type I collagen could improve the osteoconduction and osseointegration of TC implants.

An evaluation of association between a novel hippocampal biology related SNP (rs7294919) and schizophrenia.

Recent genetic analyses have implicated several candidate susceptibility variants for schizophrenia. The single nucleotide polymorphism (SNP) rs7294919 is likely a schizophrenia-susceptibility variant according to its significant association with hippocampal volume, hippocampus function, and cognitive performance as well as the nominal association with schizophrenia. However, all previous analyses were conducted only in Europeans, and whether rs7294919 is associated with schizophrenia in other populations are yet to be tested. Here, we conducted a case-control analysis of rs7294919 with schizophrenia in six independent Chinese (N = 3) and Japanese (N = 3) samples, including a total of 7,352 cases and 10,824 controls. The results of our association analysis were not able to confirm the association of rs7294919 with schizophrenia (p = 0.51 in total samples, odds ratio = 1.02 for allele[C]). The absence of rs7294919's association in Chinese and Japanese suggest a potential genetic heterogeneity in the susceptibility of schizophrenia on this locus and also demonstrate the difficulties in replicating associations of schizophrenia across different ethnic populations.

Meta-analysis and brain imaging data support the involvement of VRK2 (rs2312147) in schizophrenia susceptibility.

Recent genome-wide association studies have reported a set of schizophrenia susceptibility genes, but many of them await further replications in additional samples. Here we analyzed 5 genome-wide supported variants in a Han Chinese sample, and the variant rs2312147 at VRK2 showed significant association, which was confirmed in the meta-analysis combining multiple Asian and European samples (P=3.17×10(-4), N=7498). Rs2312147 is also associated with brain structure in healthy subjects, including the total brain volume and the white matter volume. Gene expression analyses indicated an up-regulation of VRK2 in schizophrenia patients. Our data provide further evidence for the contribution of VRK2 to schizophrenia.

ZNF804A and schizophrenia susceptibility in Asian populations.

ZNF804A, a recently identified risk gene for schizophrenia, has been extensively investigated and the principle finding for this locus has been the association with SNP rs1344706 in populations of European ancestries. However, in Asian populations, only a few studies have been conducted for rs1344706 and the results were inconsistent. Here, we studied rs1344706 and schizophrenia susceptibility in multiple Asian case-control samples (10 Chinese and 2 Japanese samples; N = 21,062), and the meta-analyses indicated non-significant association of rs1344706 with schizophrenia (P = 0.26), suggesting the same SNP identified in European samples is not predisposing risk in Asians. Further genotyping and association analyses of a set of SNPs spanning the entire genomic region of ZNF804A (520 kb) identified no association except for SNP rs359895 (P = 7.8 x 10(-5) , N = 5,172), a newly reported risk SNP located in the ZNF804A promoter region with functional implications. This suggests that ZNF804A may also contribute to schizophrenia susceptibility in Asians although the risk SNP is different from that in Europeans, and it was supported by the detected up-regulation of ZNF804A mRNA expression in the blood cells of Chinese schizophrenia patients compared with normal controls (P = 0.004). Additionally, the linkage disequilibrium (LD) structure analyses using data from HapMap indicated distinct LD blocks across ZNF804A between Chinese and Europeans, which may explain the different association patterns between them, and also highlight the compounding difficulty of genetic studies of complex diseases like schizophrenia when studying multiple ethnic populations.

Genome-wide supported psychosis risk variant in ZNF804A gene and impact on cortico-limbic WM integrity in schizophrenia.

Genome-wide association, case association genetic and meta-analytic studies have highlighted ZNF804A as a robust genome-wide supported susceptibility gene for schizophrenia (SCZ). In view of the possible involvement of ZNF804A gene in early neurodevelopment and cellular processes including oligodendrocyte proliferation and differentiation, we examined the effect of ZNF804A on brain WM (WM) integrity in patients with SCZ. Based on extant data in healthy controls (HC), we hypothesized that ZNF804A risk variant rs1344706 is associated with lower fractional anisotropy (FA) in brain regions within cortico-limbic circuits, namely frontal, parietal, medial temporal lobes, and cingulate gyri in SCZ. A total of 200 Chinese participants (125 patients with DSM-IV diagnosis of SCZ and 75 controls) were genotyped using blood samples, a subset of 153 participants (89 patients with DSM-IV diagnosis of SCZ and 64 controls) underwent structural magnetic resonance imaging and diffusion tensor imaging (DTI). There are significant effects of diagnosis (left cingulate gyrus: Adjusted F(1,149) = 9.36, P = 0.003) and diagnosis-genotype interactions (left parietal lobe: Adjusted F(1,147) = 7.39, P = 0.007; right parietal lobe: Adjusted F(1,147) = 6.95, P = 0.009; right medial temporal lobe: Adjusted F(1,147) = 8.79, P = 0.004; left cingulate gyrus: Adjusted F(1,147) = 8.02, P = 0.005). Specifically, we found that patients with SCZ who are risk T homozygotes have lower FA in bilateral parietal lobes, and left cingulate gyrus compared with G carriers. Compared with risk T homozygotes in HC, patients with SCZ who are risk T homozygotes have decreased FA in bilateral parietal lobes, and left cingulate gyrus as well as right medial temporal lobe. Our findings suggest that ZNF804A risk variant influence WM integrity involving cortico-limbic brain regions in SCZ and highlight the importance of investigating the impact of genome-wide supported risk factors on intermediate phenotypes with potential to shed light on the neurobiology of SCZ.

[The antibacterial activity of plasma sprayed silver-containing hydroxyapatite coatings].

PURPOSE: To study the antibacterial activity of plasma sprayed silver-containing hydroxyapative(HA) coatings. METHODS: Silver-containing HA coatings were prepared on titanium substrated by vacuum plasma spraying (VPS). The samples were divided into 4 groups according to weight percent of the antimicrobial: group HA0 (0%),group HA1 (1%),group HA3 (3%) and group HA5 (5%). The antimicrobial properties against Streptococcus mutans were assayed with the pellicle-sticking method. RESULTS: When the weight percent of the silver was >3%, the silver-containing HA coatings exhibited significant anti-bacterial effects against Streptococcus mutans. CONCLUSION: The silver-containing HA coating has good inhibitory effect on Streptococcus mutans.

[Study on the slow release of silver ion from silver containing antibacterial HA coating material].

PURPOSE: To study the slow release of silver ion from silver containing antibacterial HA coating material. METHODS: Ti coated with HA samples were prepared using vacuum plasma spraying. In group 1, HA coating materials contained 5%(wt%) silver-zirconium phosphate antimicrobial. In Group 2, pure HA coating materials were used. The samples were immersed into the newborn calf serum and stored under anaerobic environment at constant temperatures of 37 degrees centigrade, avoiding light. The newborn calf serum was set as control. The Ag(+) ion concentration was detected and calculated using atomic absorption spectroscopy at 1,7,14 days. RESULTS: The Ag(+) ion contents of group 1 were 250 ng, 425 ng and 417 ng respectively at the end of 1,7,14 days. The release rate of Ag(+) ion became slow with the lapse of time. The release of Ag(+) ion became stable during 7-14 days. The Ag(+) ion content decreased on the 14th day. The Ag(+) ion content of group 2 could be ignored. CONCLUSIONS: The release of Ag(+) ion from silver containing HA coating materials is little and becomes stable on the 7th day. There might be reabsorption of Ag(+) ion on the 14th day.

[Preparation and structural detection of antibacterial hydroxyapatite coating material on Ti implant].

PURPOSE: To investigate the method for preparing antibacterial hydroxyapatite coating material on Ti implant,and detect its surface feature, chemical composition and the crystal structure. METHODS: The antibacterial hydroxyapatite coating material which contained silver-zirconium phosphate antimicrobial was prepared on the Ti implant by using vacuum plasma spraying technology. Samples were divided into 4 groups according to weight percent of the antimicrobial: group A (0), group B (2%), group C (5%) and group D (10%). The surface feature of each sample was observed under scanning electric microscope. The chemical composition and the crystal structure was detected by electronic probe and X-ray diffraction method respectively. RESULTS: The surface feature of each sample showed globular granule with caky structure and air pore. The crystal structure of group A, B, C mainly showed characteristic absorption band of Ca10(OH)2(PO4)6 which degraded while antimicrobial content increased. Except Ca10(OH)2(PO4)6 and CaZr (PO4)2, Na6CaP2O09 also appeared in group D. Ag+ could not be detected by electronic probe in group A and B. The contents of Ag+ in group C and D were similar. CONCLUSION: The antibacterial hydroxyapatite coating material which contained silver can be prepared on the Ti implant by using vacuum plasma spraying technology. The appropriate weight percent of the antimicrobial was 5%.