Differential localization and bacteriostasis of Vibrio campbellii among tissues of the Eastern oyster,Crassostrea virginica

In bivalve mollusks the roles of individual tissues in antimicrobial defense remain unclear. In this study, Crassostrea virginica were injected in the adductor muscle with 10⁵ live Vibrio campbellii. Major tissues were dissected at 10, 30, 60 or 120 min postinjection (PI); in each tissue undegraded (intact) bacteria were quantified by real-time PCR and culturable bacteria were enumerated by selective plating. At 10 min PI, accumulation of bacteria varied among tissues from approximately 2.4 × 10³ (labial palps, digestive gland) to 24.2 × 10³ (gonads) intact Vibrio g^?1. Neither distribution nor accumulation of intact bacteria changed with time except in the hemolymph. In most tissues, more than 80% of intact bacteria were culturable at 10 min PI and culturability decreased with time. In contrast, only 19% of intact bacteria in gonadal tissue could be cultured at 10 min PI, pointing to a major role for the gonadal tissues in antibacterial defense of molluscs.     

The effect of screw insertion angle and thread type on the pullout strength of bone screws in normal and osteoporotic cancellous bone models

Screw fixation can be extremely difficult to achieve in osteoporotic (OP) bone because of its low strength. This study determined how pullout strength is affected by placing different bone screws at varying angles in normal and OP bone models. Pullout tests of screws placed axially, and at angles to the pullout axis (ranging from 10° to 40°), were performed in 0.09 g cm^?3, 0.16 g cm^?3 and 0.32 g cm^?3 polyurethane (PU) foam. Two different titanium alloy bone screws were used to test for any effect of thread type (i.e. cancellous or cortical) on the screw pullout strength. The cancellous screw required a significantly higher pullout force than the cortical screw (p < 0.05). For both screws, pullout strength significantly increased with increasing PU foam density (p < 0.05). For screws placed axially, and sometimes at 10°, the observed mechanism of failure was stripping of the internal screw threads generated within the PU foam by screw insertion. For screws inserted at 10°, 20°, 30° and 40°, the resistance to pullout force was observed to be by compression of the PU foam material above the angled screw; clinically, this suggests that compressed OP bone is stronger than unloaded OP bone.     

Peri-implant reactivity and osteoinductive potential of immobilized rhBMP-2 on titanium carriers

Recombinant human BMP-2 (rhBMP-2) was immobilized non-covalently and covalently as a monolayer on plasma vapour deposited (PVD) porous commercially pure titanium surfaces in amounts of 5–8 μg cm^?2, providing a ca. 10-fold increase vs. previously reported values [37]. Dissociation of the immobilized [¹²⁵I]rhBMP-2 from the surface occurred in a two-phase exponential decay: a first rapid phase (ca. 15% of immobilized BMP-2) with a half-life of 1–2 days and a second slow sustained release phase (ca. 85% of immobilized BMP-2) with a half-life of 40–60 days. Dissociation rate constants of sustained release of k_?1 = 1.3–1.9 × 10^?7 s^?1 were determined, allowing an estimation of the binding constants (K_A) for the adsorbed rhBMP-2 monolayer, to be around 10¹² M^?1. The rhBMP-2-coated surfaces showed a high level of biological activity, as demonstrated by in vitro epifluorescence tests for alkaline phosphatase with MC3T3-E1 cells and in vivo experiments. In vivo osteoinductivity of rhBMP-2-coated implants was investigated in a gap-healing model in the trabecular bone of the distal femur condylus of sheep. Healing occurred without inflammation or capsule formation. The calculated concentration of released rhBMP-2 in the 1 mm gap ranged from 20 to 98 nM – well above the half-maximal response concentration (K_0.5) for inducing alkaline phosphatase in MC3T3-E1 cells. After 4, 9 and 12 weeks the bone density (BD) and bone-to-implant contact (BIC) of the explanted implants were assessed histomorphometrically. Implants with immobilized rhBMP-2 displayed a significant (2- to 4-fold) increase in BD and BIC values vs. negative controls after 4–9 weeks. Integration of implants by trabecular bone was achieved after 4 weeks, indicating a mean “gap-filling rate” of ～250 μm week^?1. Integration of implants by cortical bone was observed after 9 weeks. Control implants without rhBMP-2 were not osseointegrated. This study demonstrates the feasibility of enhancing peri-implant osseointegration and gap bridging by immobilized rhBMP-2 on implant surfaces which may serve as a model for future clinical applications.     

The role of doxorubicin in non-viral gene transfer in the lung

Proteasome inhibitors have been shown to increase adeno-associated virus (AAV)-mediated transduction in vitro and in vivo. To assess if proteasome inhibitors also increase lipid-mediated gene transfer with relevance to cystic fibrosis (CF), we first assessed the effects of doxorubicin and N-acetyl-l-leucinyl-l-leucinal-l-norleucinal in non-CF (A549) and CF (CFTE29o-) airway epithelial cell lines. CFTE29o- cells did not show a response to Dox or LLnL; however, gene transfer in A549 cells increased in a dose-related fashion (p < 0.05), up to approximately 20-fold respectively at the optimal dose (no treatment: 9.3 × 10⁴ ± 1.5 × 10³, Dox: 1.6 × 10⁶ ± 2.6 × 10⁵, LLnL: 1.9 × 10⁶ ± 3.2 × 10⁵ RLU/mg protein). As Dox is used clinically in cancer chemotherapy we next assessed the effect of this drug on non-viral lung gene transfer in vivo. CF knockout mice were injected intraperitoneally (IP) with Dox (25–100 mg/kg) immediately before nebulisation with plasmid DNA carrying a luciferase reporter gene under the control of a CMV promoter/enhancer (pCIKLux) complexed to the cationic lipid GL67A. Dox also significantly (p < 0.05) increased expression of a plasmid regulated by an elongation factor 1α promoter (hCEFI) approximately 8-fold. Although administration of Dox before lung gene transfer may not be a clinically viable option, understanding how Dox increases lung gene expression may help to shed light on intracellular bottle-necks to gene transfer, and may help to identify other adjuncts that may be more appropriate for use in man.     

Discovery of low mucus adhesion surfaces

Mucus secretion from the body is ubiquitous, and finding materials that resist mucus adhesion is a major technological challenge. Here, using a high throughput platform with photo-induced graft polymerization, we first rapidly synthesized, screened and tested a library of 55 different surfaces from six functional monomer classes to discover porcine intestinal low mucus adhesion surfaces using a 1 h static mucus adsorption protocol. From this preliminary screen, two chemistries, a zwitterionic ([2-(acryloyloxy)ethyl] trimethylammonium chloride) and a multiple hydroxyl (N-[tris(hydroxymethyl)methyl]acrylamide) surface, exhibited significantly low mucus adhesion from a Langmuir-type isotherm when exposed to increasing concentrations of mucus for 24 h. Apolar or hydrophobic interactions were likely the dominant attractive forces during mucus binding since many polar or hydrophilic monomers reduced mucus adhesion. Hansen solubility parameters were used to illustrate the importance of monomer polarity and hydrogen bonding in reducing mucus adsorption. For a series of polyethylene glycol (PEG) monomers with changing molecular weight from 144 g mol^?1 to 1100 g mol^?1, we observed an excellent linear correlation (R² = 0.998) between relative amount adsorbed and the distance from a water point in a specialized Hansen solubility parameter plot, emphasizing the role of surface–water interactions for PEG modified surfaces.     

Identification of phagocytic cells,NK-like cytotoxic cell activity and the production of cellular exudates in the coelomic cavity of adult zebrafish

Coelomic cavity (CC) cells of mature zebrafish harvested by lavage with media or trypsin–EDTA contained 0.80–1.20 × 10⁵ and 2.0–3.5 × 10⁵ cells, respectively. Media lavage was composed of granulocytes (60–80%), lymphocytes (10–20%), and NCC (4–10%). Granulocytes had large electron dense cytoplasmic paracrystalline granules and a segmented nucleus; they expressed plastin-1, myeloid specific peroxidase and MCSF mRNA; and they were NCAMP-1⁺. Lymphocytes had B- and T-cell specific mRNA and were NCAMP-1^? and NCCRP-1^?. NCC were 3 μm, NCAMP-1⁺ and NCCRP-1⁺ and did not express B- and T-cell specific mRNA. Additionally, trypsin lavage contained monocytes (marginated chromatin, low nuclear:cytoplasm ratio, sparse cytosolic granules) and macrophages (non-segmented nuclei, no margination of chromatin, abundant electron dense granules). E. coli injected into the CC were phagocytosed in a dose and time dependent fashion by granulocytes, monocytes and macrophages. NCC lysed mammalian target cells and NCAMP-1 expressing hybridoma cells in redirected lysis assays.     

TBX6-associated congenital scoliosis (TACS) as a clinically distinguishable subtype of congenital scoliosis: further evidence supporting the compound inheritance and TBX6 gene dosage model

PurposeTo characterize clinically measurable endophenotypes, implicating the TBX6 compound inheritance model.MethodsPatients with congenital scoliosis (CS) from China(N = 345, cohort 1), Japan (N = 142, cohort 2), and the United States (N = 10, cohort 3) were studied. Clinically measurable endophenotypes were compared according to the TBX6 genotypes. A mouse model for Tbx6 compound inheritance (N = 52) was investigated by micro computed tomography (micro-CT). A clinical diagnostic algorithm (TACScore) was developed to assist in clinical recognition of TBX6-associated CS (TACS).ResultsIn cohort 1, TACS patients (N = 33) were significantly younger at onset than the remaining CS patients (P = 0.02), presented with one or more hemivertebrae/butterfly vertebrae (P = 4.9 × 10^‒8), and exhibited vertebral malformations involving the lower part of the spine (T8–S5, P = 4.4 × 10^‒3); observations were confirmed in two replication cohorts. Simple rib anomalies were prevalent in TACS patients (P = 3.1 × 10^‒7), while intraspinal anomalies were uncommon (P = 7.0 × 10^‒7). A clinically usable TACScore was developed with an area under the curve (AUC) of 0.9 (P = 1.6 × 10^‒15). A Tbx6^{-/mh (mild-hypomorphic)} mouse model supported that a gene dosage effect underlies the TACS phenotype.ConclusionTACS is a clinically distinguishable entity with consistent clinically measurable endophenotypes. The type and distribution of vertebral column abnormalities in TBX6/Tbx6 compound inheritance implicate subtle perturbations in gene dosage as a cause of spine developmental birth defects responsible for about 10% of CS.     

Methanosaeta sp., the major archaeal endosymbiont of Metopus es

Epifluorescence microscopy and whole cell in situ hybridization analysis revealed the presence of Methanosaeta sp. as endosymbionts in Metopus es. Direct microscopic observation under epifluorescent microscope showed the presence of long slender rods with an average length of 3.4 μm. The number of methanogenic rods varied from 792 ± 12 in a single M. es cell with a biovolume of 3.4 × 10⁵ μm³. At the exponential growth stage, a single symbiotic methanogen in M. es produced about 1 fmol methane/h leading to a methane production rate of 0.85 pmol/ciliate/h. The presence of endosymbiotic methanogens in the domain archaea and Methanosaeta sp. was confirmed by FISH with ARCH 915 and MX 825 oligonucleotide probes specific to domain archaea and Methanosaeta respectively. The homogenized cells of M. es also showed bright fluorescing rods with MX 825 hybridization. The culture obtained on inoculation of the released endosymbiotic organisms on Methanosaeta-specific medium lent support to the growth of long slender rods having the same range of mean length (3.6 μm) as that of the endosymbiotic methanogens observed. Both intra- and extracellular production of acetate was detected in M. es culture.     

Hydraulic permeability of multilayered collagen gel scaffolds under plastic compression-induced unidirectional fluid flow

Under conditions of free fluid flow, highly hydrated fibrillar collagen gels expel fluid and undergo gravity driven consolidation (self-compression; SC). This process can be accelerated by the application of a compressive stress (plastic compression; PC) in order to generate dense collagen scaffolds for tissue engineering. To define the microstructural evolution of collagen gels under PC, this study applied a two-layer micromechanical model that was previously developed to measure hydraulic permeability (k) under SC. Radially confined PC resulted in unidirectional fluid flow through the gel and the formation of a dense lamella at the fluid expulsion boundary which was confirmed by confocal microscopy of collagen immunoreactivity. Gel mass loss due to PC and subsequent SC were measured and applied to Darcy’s law to calculate the thickness of the lamella and hydrated layer, as well as their relative permeabilities. Increasing PC level resulted in a significant increase in mass loss fraction and lamellar thickness, while the thickness of the hydrated layer dramatically decreased. Permeability of lamella also decreased from 1.8 × 10^?15 to 1.0 × 10^?15 m² in response to an increase in PC level. Ongoing SC, following PC, resulted in a uniform decrease in mass loss and k with increasing PC level and as a function SC time. Experimental k data were in close agreement with those estimated by the Happel model. Calculation of average k values for various two-layer microstructures indicated that they each approached 10^?15–10^?14 m² at equilibrium. In summary, the two-layer micromechanical model can be used to define the microstructure and permeability of multi-layered biomimetic scaffolds generated by PC.     

Three-dimensional quantification of susceptibility artifacts from various metals in magnetic resonance images

Susceptibility artifacts generated in magnetic resonance (MR) images were quantitatively evaluated for various metals using a three-dimensional (3-D) artifact rendering to demonstrate the correlation between magnetic susceptibility and artifact volume. Ten metals (stainless steel, Co–Cr alloy, Nb, Ti, Zr, Mo, Al, Sn, Cu and Ag) were prepared, and their magnetic susceptibilities measured using a magnetic balance. Each metal was embedded in a Ni-doped agarose gel phantom and the MR images of the metal-containing phantoms were taken using 1.5 and 3.0 T MR scanners under both fast spin echo and gradient echo conditions. 3-D renderings of the artifacts were constructed from the images and the artifact volumes were calculated for each metal. The artifact volumes of metals decreased with decreasing magnetic susceptibility, with the exception of Ag. Although Sn possesses the lowest absolute magnetic susceptibility (1.8 × 10^?6), the artifact volume from Cu (?7.8 × 10^?6) was smaller than that of Sn. This is because the magnetic susceptibility of Cu was close to that of the agarose gel phantom (?7.3 × 10^?6). Since the difference in magnetic susceptibility between the agarose and Sn is close to that between the agarose and Ag (?17.5 × 10^?6), their artifact volumes were almost the same, although they formed artifacts that were reversed in all three dimensions.     

Development of a novel multiplex PCR for the detection and differentiation of Salmonella enterica serovars Typhi and Paratyphi A

In this study, we developed a multiplex polymerase chain reaction (mPCR) assay for pan-Salmonella detection as well as for specific detection of serovars Typhi and Paratyphi A. The assay detects members of the Salmonella genus by amplifying the outer membrane protein C (ompC). The presence of either Salmonella serovar Typhi or Paratyphi A is indicated by amplification of the putative regulatory protein gene STY4220, which is common to both serovars. Further differentiation of the serovars was achieved by targeting the intergenic region (SSPAI) between SSPA1723a and SSPA1724 in serovar Paratyphi A, and stgA, a fimbrial subunit protein, in serovar Typhi. mPCR was evaluated using 124 clinical and reference Salmonella serovars. S. enterica serovars Typhi and Paratyphi A were detected at 100% specificity and sensitivity. Each PCR reaction detected approximately 1 pg of Salmonella genomic DNA. Sensitivity of the PCR when tested on 8-h-enriched spiked blood samples of serovars Typhi and Paratyphi A was estimated at 4.5 × 10⁴–5.5 × 10⁴ CFU/ml, with similar detection levels observed for spiked fecal samples. This mPCR could prove to be a useful diagnostic tool for the detection and differentiation of serovars Typhi and Paratyphi A.     

Suitability of DCPs with Screw Locking Elements to allow sufficient interfragmentary motion to promote secondary bone healing of osteoporotic fractures

This paper analyses the suitability of a system comprising a Dynamic Compression Plate (DCP) and Screw Locking Elements (SLEs) to allow sufficient interfragmentary motion to promote secondary bone healing in osteoporotic fractures.Four fixation systems were mounted on bone-simulating reinforced epoxy bars filled with solid rigid polyurethane foam. Group 1, used for comparison purposes, represents a system comprised of a Locking Compression Plate (LCP) and eight locking screws. Groups 2 and 3 represent a system comprised of a DCP plate with eight cortical screws and two SLEs placed on the screws furthest from (group 2) and nearest to (group 3) the fracture. Group 4 represents the system comprised of a DCP plate with SLEs placed on all eight cortical screws. Cyclic compression tests of up to 10,000 load cycles were performed in order to determine the parameters of interest, namely the stiffnesses and the interfragmentary motion of the various configurations under consideration. Tukey's multiple comparison test was used to analyse the existence or otherwise of significant differences between the means of the groups.At 10,000 cycles, interfragmentary motion at the far cortex for group 2 was 0.60 ± 0.04 mm and for group 3 0.59 ± 0.03 mm (there being no significant differences: p = 0.995). The mean interfragmentary motion at the far cortex of the LCP construct was 70% less than that of the two groups with 2SLEs (there being significant differences: p = 1.1 × 10^?8). In the case of group 4 this figure was 45% less than in groups 2 and 3 (there being significant differences: p = 5.6 × 10^?6). At 10,000 cycles, interfragmentary motion at the near cortex for group 2 was 0.24 ± 0.06 mm and for group 3 0.24 ± 0.03 mm (there being no significant differences: p = 1.000). The mean interfragmentary motion at the near cortex of the LCP construct was 70.8% less than that of the two groups with 2SLEs (there being significant differences: p = 0.011). In the case of group 4 this figure was 66.7% less than in groups 2 and 3 (there being significant differences: p = 0.016). The mean stiffness at 10,000 cycles was 960 ± 110 N mm^?1 for group 2 and 969 ± 53 N mm^?1 for group 3 (there being no significant differences: p = 1.000). For group 1 (the LCP construct) the mean stiffness at 10,000 cycles was 3144 ± 446 N mm^?1, 3.25 times higher than that of groups 2 and 3 (there being significant differences: p = 0.00002), and 1.6 times higher than that of the DCP + 8SLEs construct (1944 ± 408 N mm^?1, there being significant differences: p = 0.007).It is concluded that using the DCP + 2SLEs construct sufficient interfragmentary motion is ensured to promote secondary bone healing. However, if too many SLEs are used the result may be, as with the LCP, an excessively rigid system for callus formation.     

Oxidation of elemental sulfur,tetrathionate and ferrous iron by the psychrotolerant Acidithiobacillus strain SS3

Mesophilic iron and sulfur-oxidizing acidophiles are readily found in acid mine drainage sites and bioleaching operations, but relatively little is known about their activities at suboptimal temperatures and in cold environments. The purpose of this work was to characterize the oxidation of elemental sulfur (S⁰), tetrathionate (S₄O₆^2?) and ferrous iron (Fe²⁺) by the psychrotolerant Acidithiobacillus strain SS3. The rates of elemental sulfur and tetrathionate oxidation had temperature optima of 20° and 25 °C, respectively, determined using a temperature gradient incubator that involved narrow (1.1 °C) incremental increases from 5° to 30 °C. Activation energies calculated from the Arrhenius plots were 61 and 89 kJ mol^?1 for tetrathionate and 110 kJ mol^?1 for S⁰ oxidation. The oxidation of elemental sulfur produced sulfuric acid at 5 °C and decreased the pH to approximately 1. The low pH inhibited further oxidation of the substrate. In media with both S⁰ and Fe²⁺, oxidation of elemental sulfur did not commence until all available ferrous iron was oxidized. These data on sequential oxidation of the two substrates are in keeping with upregulation and downregulation of several proteins previously noted in the literature. Ferric iron was reduced to Fe²⁺ in parallel with elemental sulfur oxidation, indicating the presence of a sulfur:ferric iron reductase system in this bacterium.     

Microporous calcium phosphate ceramics as tissue engineering scaffolds for the repair of osteochondral defects: Biomechanical results

This work investigated the suitability of microporous β-tricalcium phosphate (TCP) scaffolds pre-seeded with autologous chondrocytes for treatment of osteochondral defects in a large animal model. Microporous β-TCP cylinders (Ø 7 mm; length 25 mm) were seeded with autologous chondrocytes and cultured for 4 weeks in vitro. Only the upper end of the cylinder was seeded with chondrocytes. Chondrocytes formed a multilayer on the top. The implants were then implanted in defects (diameter 7 mm) created in the left medial femoral condyle of ovine knees. The implants were covered with synovial membrane from the superior recess of the same joint. For the right knees, an empty defect with the same dimensions served as control. Twenty-eight sheep were split into 6-, 12-, 26- and 52 week groups of seven animals. Indentation tests with a spherical (Ø 3 mm) indenter were used to determine the biomechanical properties of regenerated tissue. A software-based limit switch was implemented to ensure a maximal penetration depth of 200 μm and maximal load of 1.5 N. The achieved load, the absorbed energy and the contact stiffness were measured. Newly formed cartilage was assessed with the International Cartilage Repair Society Visual Assessment Scale (ICRS score) and histomorphometric analysis. Results were analysed statistically using the t-test, Mann–Whitney U-test and Wilcoxon test. Statistical significance was set at p < 0.05. After 6 weeks of implantation, the transplanted area tolerated an indentation load of 0.05 ± 0.20 N. This value increased to 0.10 ± 0.06 N after 12 weeks, to 0.27 ± 0.18 N after 26 weeks, and 0.27 ± 0.11 N after 52 weeks. The increase in the tolerated load was highly significant (p < 0.0001), but the final value was not significantly different from that of intact cartilage (0.30 ± 0.12 N). Similarly, the increase in contact stiffness from 0.87 ± 0.29 N mm?¹ after 6 weeks to 3.14 ± 0.86 N mm^?1 after 52 weeks was highly significant (p < 0.0001). The absorbed energy increased significantly (p = 0.02) from 0.74 × 10^?6 ± 0.38 × 10^?6 Nm after 6 weeks to 2.83 × 10^?6 ± 1.35 × 10^?6 Nm after 52 weeks. At 52 weeks, the International Cartilage Repair Society (ICRS) scores for the central area of the transplanted area and untreated defects were comparable. In contrast, the score for the area from the edge to the centre of the transplanted area was significantly higher (p = 0.001) than the score for the unfilled defects. A biomechanically stable cartilage was built outside the centre of defect. After 52 weeks, all but one empty control defect were covered by bone and a very thin layer of cartilage (ICRS 7 points). The empty hole could still be demonstrated beneath the bone. The histomorphometric evaluation revealed that 81.0 ± 10.6% of TCP was resorbed after 52 weeks. The increase in TCP resorption and replacement by spongy bone during the observation period was highly significant (p < 0.0001). In this sheep trial, the mechanical properties of microporous TCP scaffolds seeded with transplanted autologous chondrocytes were similar to those of natural cartilage after 52 weeks of implantation. However, the central area of the implants had a lower ICRS score than healthy cartilage. Microporous TCP was almost fully resorbed at 52 weeks and replaced by bone.     

Contribution of dendritic cell immunoreceptor (DCIR) polymorphisms in susceptibility of systemic lupus erythematosus and primary Sjogren’s syndrome

Dendritic cell immunoreceptor (DCIR) has previously shown an association with rheumatoid arthritis (RA) in Caucasians and Han Chinese. This study was aimed to further investigate whether DCIR polymorphisms are novel susceptibility factors for other autoimmune diseases, i.e. systemic lupus erythematosus (SLE) and primary Sjogren’s syndrome (SS). A total of 1502 patients with SLE, 476 patients with primary SS, and 1278 non-related healthy controls were enrolled in the study. The single-nucleotide polymorphisms (SNPs) rs2377422 and rs10840759 were genotyped using TaqMan assay. The differences in allelic and genotypic distribution between two groups were assessed using Pearson chi-square test, and logistic regression adjusting for age and sex, respectively. P-value <0.025 was considered statistically significant by Bonferroni correction. The SNP rs2377422 confers an increased susceptibility risk to both SLE (allele model: P = 7.65 × 10⁻⁴, OR 1.20; genotype recessive model: P = 0.012, OR 1.29), and primary SS (allele model: P = 3.74 × 10⁻⁴, OR 1.31; genotype dominant model: P = 1.62 × 10⁻⁴, OR 2.02). There is no association between rs10840759 and SLE or primary SS. In conclusion, DCIR SNP rs2377422 is a novel genetic susceptibility factor for both SLE and primary SS.     

Association study of rs924080 and rs11209032 polymorphisms of IL23R-IL12RB2 in a Northern Chinese Han population with Behcet’s disease

ObjectivesTwo genome-wide association studies (GWAS) have identified the IL-23 receptor- IL-12 receptor β2 (IL23R-IL12RB2) as the susceptibility genetic region in Turkish and Japanese population with Behçet’s disease (BD). We investigated the association of this region with BD in a Northern Chinese Han population.MethodsA total of 407 patients with BD and 421 healthy controls were genotyped for single nucleotide polymorphisms (SNPs) rs924080 and rs11209032 using the Sequenom MassArray system.ResultsStatistically significant associations with BD were detected at two SNPs namely, rs924080 and rs11209032, both, by allele analysis (OR = 1.58, 95% CI = 1.25–2.00, P_c = 2.52 × 10⁻⁴, and OR = 1.45, 95% CI = 1.19–1.76, P_c = 3.46 × 10⁻⁴, respectively), and genotype analysis (P_c = 1.22 × 10⁻³ and P_c = 1.77 × 10⁻³, respectively). Significant differences were observed in the genotype frequency distribution for these SNPs under the additive, dominant and recessive models (all P_c < 0.05). The haplotypes (AT and GC) formed by the two SNPs were associated with BD (all permutation P < 0.05). A meta-analysis also appeared to support the association of the two SNPs with BD.ConclusionSNPs (rs924080 and rs11209032) of the IL23R-IL12RB2 region were found to be associated with BD in a Northern Chinese Han population.     

Accurate characterization of pure silicon-substituted hydroxyapatite powders synthesized by a new precipitation route

This paper presents a new aqueous precipitation method to prepare silicon-substituted hydroxyapatites Ca₁₀(PO₄)_6?y(SiO₄)_y(OH)_2?y(V_OH)_y (SiHAs) and details the characterization of powders with varying Si content up to y = 1.25 mol mol_SiHA^?1. X-ray diffraction, transmission electron microscopy, solid-state nuclear magnetic resonance and Fourier transform infrared spectroscopy were used to accurately characterize samples calcined at 400 °C for 2 h and 1000 °C for 15 h. This method allows the synthesis of monophasic SiHAs with controlled stoichiometry. The theoretical maximum limit of incorporation of Si into the hexagonal apatitic structure is y < 1.5. This limit depends on the OH content in the channel, which is a function of the Si content, temperature and atmosphere of calcination. These results, particularly those from infrared spectroscopy, raise serious reservations about the phase purity of previously prepared and biologically evaluated SiHA powders, pellets and scaffolds in the literature.     

Is Parkinson disease associated with lysosomal integral membrane protein type-2?: Challenges in interpreting association data

Several genetic risk factors have been identified for Parkinson disease (PD), including mutations in glucocerebrosidase (GBA1). Recently, two single nucleotide polymorphisms (SNPs) described as SCARB2 SNPs were reported to be associated with PD. SCARB2 is an attractive candidate gene for PD as it encodes for lysosomal integral membrane protein type 2 (LIMP-2), a protein involved in transporting glucocerebrosidase from the ER to the lysosome. The first SNP, rs6812193, located 64 kb upstream of SCARB2, was identified in a Parkinson disease Genome Wide Association study of Americans with European ancestry (p = 7.6 × 10^? 10, OR = 0.84), but was not replicated in a study in the Han Chinese. The second SNP, rs6825004, located within intron 2 of SCARB2 was reported in an association study of Parkinson disease in Greece (p = 0.02, OR = 0.68). We explored whether the two SNPs impact SCARB2 expression or LIMP-2 protein levels, testing fifteen control samples. First, the genotypes for each subject were determined for both SNPs using a Taqman assay. Then, RNA and protein were extracted from the corresponding cell pellets. Neither the relative RNA expression by real-time PCR, nor LIMP-2 levels on Western blots correlated with SNP genotype. Thus, these two reported SNPs may not be related to SCARB2 and demonstrate the challenges in interpreting some association studies. While LIMP-2 could still play a role in PD pathogenesis, this study does not provide evidence that the SNPs identified are in fact related to LIMP-2.     

Effect of silicon content on the sintering and biological behaviour of Ca10(PO4)6-x(SiO4)x(OH)2-x ceramics

Silicated hydroxyapatite powders (Ca₁₀(PO₄)_6-x(SiO₄)_x(OH)_2-x; Si_xHA) were synthesized using a wet precipitation method. The sintering of Si_xHA ceramics with 0 ? x ? 1 was investigated. For 0 ? x ? 0.5, the sintering rate and grain growth decreased slightly with the amount of silicate. For larger amounts, the sintering behaviour differed with the formation of secondary phases before total densification. Sintering parameters (temperature and time) were adjusted to each composition to produce dense materials having similar microstructure without formation of these secondary phases. Dense ceramics made of pure hydroxyapatite and Si_xHA containing various amounts of silicate (up to x = 0.6) were biologically tested in vitro with human osteoblast-like cells. The proliferation of cells on the surface of the ceramics increased up to 5 days of culture, indicating that the materials were biocompatible. However, the silicon content did not influence the cell proliferation.     

Polygenic risk scores and breast and epithelial ovarian cancer risks for carriers of BRCA1 and BRCA2 pathogenic variants

PurposeWe assessed the associations between population-based polygenic risk scores (PRS) for breast (BC) or epithelial ovarian cancer (EOC) with cancer risks for BRCA1 and BRCA2 pathogenic variant carriers.MethodsRetrospective cohort data on 18,935 BRCA1 and 12,339 BRCA2 female pathogenic variant carriers of European ancestry were available. Three versions of a 313 single-nucleotide polymorphism (SNP) BC PRS were evaluated based on whether they predict overall, estrogen receptor (ER)–negative, or ER-positive BC, and two PRS for overall or high-grade serous EOC. Associations were validated in a prospective cohort.ResultsThe ER-negative PRS showed the strongest association with BC risk for BRCA1 carriers (hazard ratio [HR] per standard deviation = 1.29 [95% CI 1.25–1.33], P = 3×10⁻⁷²). For BRCA2, the strongest association was with overall BC PRS (HR = 1.31 [95% CI 1.27–1.36], P = 7×10⁻⁵⁰). HR estimates decreased significantly with age and there was evidence for differences in associations by predicted variant effects on protein expression. The HR estimates were smaller than general population estimates. The high-grade serous PRS yielded the strongest associations with EOC risk for BRCA1 (HR = 1.32 [95% CI 1.25–1.40], P = 3×10⁻²²) and BRCA2 (HR = 1.44 [95% CI 1.30–1.60], P = 4×10⁻¹²) carriers. The associations in the prospective cohort were similar.ConclusionPopulation-based PRS are strongly associated with BC and EOC risks for BRCA1/2 carriers and predict substantial absolute risk differences for women at PRS distribution extremes.