Interfacial shear strength of bioactive‐coated carbon fiber reinforced polyetheretherketone after in vivo implantation

Despite the excellent osseointegration of carbon‐fiber‐reinforced polyetheretherketone (CFR/PEEK) with a surface hydroxyapatite (HA) coating, the bone‐implant interfacial shear strength of HA‐coated CFR/PEEK after osseointegration is unclear. We examined the interfacial shear strength of HA‐coated CFR/PEEK implants after in vivo implantation in a rabbit femur‐implant pull‐out test model. HA coating was performed by a newly developed method. Uncoated CFR/PEEK, HA‐coated blasted titanium alloy, and uncoated blasted titanium alloy were used as control implants. The implants were inserted into drilled femoral cortex, and pull‐out tests were conducted after 6 and 12 weeks of implantation to determine maximum interfacial shear strength. The HA‐coated CFR/PEEK (15.7 ± 4.5 MPa) and HA‐coated titanium alloy (14.1 ± 6.0 MPa) exhibited significantly larger interfacial shear strengths than the uncoated CFR/PEEK (7.7 ± 1.8 MPa) and the uncoated titanium alloy (7.8 ± 2.1 MPa) at 6 weeks. At 12 weeks, only the uncoated CFR/PEEK (8.3 ± 3.0 MPa) exhibited a significantly smaller interfacial shear strength, as compared to the HA‐coated CFR/PEEK (17.4 ± 3.6 MPa), HA‐coated titanium alloy (14.2 ± 4.8 MPa), and uncoated titanium alloy (15.0 ± 2.6 MPa). Surface analysis of the removed implants revealed detachment of the HA layer in both the HA‐coated CFR/PEEK and titanium alloy implants. The proposed novel HA coating method of CFR/PEEK significantly increased interfacial shear strength between bone and CFR/PEEK. The achieved interfacial shear strength of the HA‐coated CFR/PEEK implant is of the same level as that of grit‐blasted titanium alloy with HA. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1618–1625, 2012     

Red-green and yellow-blue opponent-color responses as a function of retinal eccentricity.

Using the hue cancellation technique, I measured the spectral sensitivities of red-green (r-g) and yellow-blue (y-b) opponent-color responses of two color-normal observers at 0 (fovea), 3.3, 10, 21, and 31 degrees along the horizontal meridian of the temporal retina. The stimulus size as a function of retinal eccentricity was varied according to the cortical magnification factor. I found that the net spectral sensitivity (i.e. corrected for macular pigment) of the r-g channel was approximately constant as a function of retinal eccentricity. On the other hand, the net spectral sensitivity of the y-b channel was not constant. For the y-b channel I found a constant spectral sensitivity as a function of eccentricity when no macular correction was made. This means that the y-b system changes its yellow and blue responses with eccentricity to counterbalance the effects of macular pigment.     

Effect of hepatotoxic or nephrotoxic agents on the induction of colon cancers in rats by 1,2-dimethylhydrazine

The effects of liver injury induced by p,p′-diaminodiphenylmethane (DDPM) and of kidney injury induced by N-(3,5-dichlorophenyl)succinimide (NDPS) on 1,2-dimethylhydrazine (DMH) colon carcinogenesis were examined in rats. Prior administration of either DDPM or NDPS before DMH injection resulted in no significant differences in tumor incidences, but differences were noted in histological pattern, tumor size, and extent of invasion.     

Comparative study of interaction mode of diazepines with human serum albumin and alpha 1-acid glycoprotein.

The binding of nine diazepines to human serum albumin (HSA) and to alpha 1-acid glycoprotein (AGP) was investigated by means of fluorescence and circular dichroism (CD) spectroscopies. The binding parameters of diazepam obtained from fluorescence agreed with those obtained from CD measurements. Diazepines have one tight binding site on both HSA and AGP. The binding parameters (nK) of the diazepine: HSA systems are slightly higher than those of diazepine:AGP systems. The relationship between the binding parameters for these two serum proteins and the physicochemical parameters of diazepines was studied by multiple regression analysis to elucidate the binding mode. Moreover, the effects of long-chain fatty acids and cesium chloride on the binding of diazepines to HSA and AGP were also studied. The driving force for the binding of diazepines to both proteins appears to be hydrophobic interaction. In addition, steric effects and electrostatic interactions may also contribute to the binding of diazepines to HSA and AGP, respectively.     

Vinyl polymerization by metal complexes, 21. Initiation mechanism of vinyl polymerization by amine-copper(ii) complexes in the presence of carbon tetrachloride

In order to elucidate the initiation mechanism of the vinyl polymerization by amine-copper(II) complexes in aqueous solution, in the presence of carbon tetrachloride, the reaction of amine-copper(II) complexes with carbon tetrachloride was studied by ESR, visible spectroscopy, and the spin trapping method. The ESR signal of copper(II) disappeared during the reaction, suggesting the reduction of copper(II) to copper(I) in the initial step of the reaction. This reduction was also ascertained both by visible spectral changes and by the cuproin coloration method. The initiation mechanism is discussed based on these results and the information about the initiating free radical species by the spin trapping method.     

Evaluation of urinary 8-hydroxydeoxyguanine in healthy Japanese people

The urinary concentration of 8-hydroxydeoxyguanine (8-OHdG), which is a biomarker of oxidative DNA damage, was measured in 248 healthy Japanese, and its correlations with life style, urinary metal elements, serum antioxidants, and other plasma or serum factors were investigated. The mean urinary concentration of 8-OHdG was 15.2+/-5.71 ng/mg creatinine. Mean urinary 8-OHdG was not significantly different in terms of age (<45, >or=45), gender, smoking (no, <20, >or=20), and alcohol consumption (no, occasionally, sometimes and usually). Moreover, multiple regression analysis showed a significant association between urinary 8-OHdG and urinary arsenic (As) or chromium (Cr), and a tendency for association between the former and aluminum (Al) and nickel (Ni). Age, gender and plasma or serum factors including antioxidants, lipid peroxide, HbA1c, BUN, and iron did not show such an association. The present study suggests that natural exposure to toxic metal elements such as As, Cr, and Ni may influence oxidative DNA damage in healthy people under usual environmental management. Therefore, the measurement of urinary metals such as As, Ni and Cr is prerequisite for the study of the relationship between urinary 8-OHdG and other variable factors.