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Hironobu Koseki,1 Masato Tomita,2 Akihiko Yonekura,2 Takashi Higuchi,1 Sinya Sunagawa,2 Koumei Baba,3,4 Makoto Osaki2 1Department of Locomotive Rehabilitation Science, Unit of Rehabilitation Sciences, 2Department of Orthopedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto, Nagasaki, Japan; 3Industrial Technology Center of Nagasaki, Ikeda, Omura, Nagasaki, Japan; 4Affiliated Division, Nagasaki University School of Engineering, Bunkyo, Nagasaki, Japan Abstract: Metal-on-metal (MoM) bearings have become popular due to a major advantage over metal-on-polymer bearings for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII) may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM bearings in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo) alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding contact tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated contact pressure of 38.5 MPa (max: 57.8 MPa), a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated bearings had lower friction coefficients, higher resistance to catastrophic damage, and prevented the adhesion of wear debris. The results of this study suggest that the CII surface stabilizes the wear status due to the low friction coefficient and low infiltration of partner materials, and these properties also prevent the adhesion of wear debris and inhibit excessive wear. Carbon is considered to be biologically inert; therefore, CII is anticipated to be applicable to the bearing surfaces of MoM prostheses. Keywords: total hip arthroplasty, metal-on-metal, carbon ion implantation

Takayuki Shida,1 Hironobu Koseki,1 Itaru Yoda,1 Hidehiko Horiuchi,1 Hideyuki Sakoda,2 Makoto Osaki11Department of Orthopedic Surgery, Graduate School of Medicine, Nagasaki University, Nagasaki, Japan; 2Division of Medical Devices, National Institute of Health Sciences, Tokyo, JapanAbstract: Bacterial adhesion to the surface of biomaterials is an essential step in the pathogenesis of implant-related infections. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis to adhere to the surface of solid biomaterials, including oxidized zirconium-niobium alloy (Oxinium), cobalt-chromium-molybdenum alloy, titanium alloy, commercially pure titanium, and stainless steel, and performed a biomaterial-to-biomaterial comparison. The test specimens were physically analyzed to quantitatively determine the viable adherent density of the S. epidermidis strain RP62A (American Type Culture Collection [ATCC] 35984). Field emission scanning electron microscope and laser microscope examination revealed a featureless, smooth surface in all specimens (average roughness

Hironobu Koseki,1 Tomohiko Asahara,1 Takayuki Shida,1 Itaru Yoda,1 Hidehiko Horiuchi,1 Koumei Baba,2 Makoto Osaki11Department of Orthopedic Surgery, Graduate School of Medicine, Nagasaki University, 2Industrial Technology Center of Nagasaki, Nagasaki, JapanBackground: Pin site infection is the most common and significant complication of external fixation. In this work, the efficacy of pins coated with titanium dioxide (TiO2) for inhibition of infection was compared with that of stainless steel control pins in an in vivo study.Methods: Pins contaminated with an identifiable Staphylococcus aureus strain were inserted into femoral bone in a rat model and exposed to ultraviolet A light for 30 minutes. On day 14, the animals were sacrificed and the bone and soft tissue around the pin were retrieved. The clinical findings and histological findings were evaluated in 60 samples.Results: Clinical signs of infection were present in 76.7% of untreated pins, but in only 36.7% of TiO2-coated pins. The histological bone infection score and planimetric rate of occupation for bacterial colonies and neutrophils in the TiO2-coated pin group were lower than those in the control group. The bone-implant contact ratio of the TiO2-coated pin group was significantly higher (71.4%) than in the control pin group (58.2%). The TiO2 was successful in decreasing infection both clinically and histomorphometrically.Conclusion: The photocatalytic bactericidal effect of TiO2 is thought to be useful for inhibiting pin site infection after external fixation.Keywords: titanium dioxide, external fixation, bactericidal activity, Staphylococcus aureus

Shida T, Koseki H, Yoda I, et al. Int J Nanomed. 2013;8(1):3955–3961.On page 3955, please note that the first affiliation has changed from "Department of Orthopedic Surgery, Graduate School of Medicine, Nagasaki University, Nagasaki, Japan" to "Department of Orthopedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan".Read the original article

Background: Bacterial contamination by airborne particles is one of the most important factors in the pathogenesis of surgical-site infections.Aim: This study aimed to identify the generation and behaviour of airborne particles around the feet of surgical staff while walking in and out of an operating theatre.Methods: Two physicians and two nurses walked in and out of a bio-clean theatre under laminar airflow, either individually or as a group. The generation and behaviour of airborne particles was filmed using a fine-particle visualization system, and the number of airborne particles per 2.83 m3 of air was counted using a laser particle counter. Each action was repeated five times, and particle counts were evaluated statistically.Findings: Airborne particles were generated from the floor and by the shoes and gown hems of the participants, whether walking individually or as a group. Numerous airborne particles were generated by the group, and significantly more particles, especially those measuring 0.3-0.5 μm, were carried up to the level of the operating table by the group than by individuals (P<0.01).Conclusions: The results of this study provide a clearer picture of the dispersion and distribution of airborne particles around the feet of staff walking in and out of an operating theatre. The findings suggest that to reduce the incidence of bacterial contamination and risk of surgical site infections, surgical staff should walk calmly and independently, if possible, near sterile areas. [ABSTRACT FROM AUTHOR]

The IGF2/ H19-imprinting control region ( ICR1) functions as an insulator to methylation-sensitive binding of CTCF protein, and regulates imprinted expression of IGF2 and H19 in a parental origin-specific manner. ICR1 methylation defects cause abnormal expression of imprinted genes, leading to Beckwith-Wiedemann syndrome ( BWS) or Silver-Russell syndrome ( SRS). Not only ICR1 microdeletions involving the CTCF-binding site, but also point mutations and a small deletion of the OCT-binding site have been shown to trigger methylation defects in BWS. Here, mutational analysis of ICR1 in 11 BWS and 12 SRS patients with ICR1 methylation defects revealed a novel de novo point mutation of the OCT-binding site on the maternal allele in one BWS patient. In BWS, all reported mutations and the small deletion of the OCT-binding site, including our case, have occurred within repeat A2. These findings indicate that the OCT-binding site is important for maintaining an unmethylated status of maternal ICR1 in early embryogenesis. [ABSTRACT FROM AUTHOR]

Accumulation of misfolded proteins in the endoplasmic reticulum (ER) induces the unfolded protein response (UPR), which alleviates protein overload in the secretory pathway. Although the UPR is activated under diverse pathological conditions, its physiological role during development and in adulthood has not been fully elucidated. Binding immunoglobulin protein (BiP) is an ER chaperone, which is central to ER function. We produced knock-in mice expressing a mutant BiP lacking the retrieval sequence to cause a defect in ER function without completely eliminating BiP. In embryonic fibroblasts, the UPR compensated for mutation of BiP. However, neonates expressing mutant BiP suffered respiratory failure due to impaired secretion of pulmonary surfactant by alveolar type II epithelial cells. Expression of surfactant protein (SP)-C was reduced and the lamellar body was malformed, indicating that BiP plays a critical role in the biosynthesis of pulmonary surfactant. Because pulmonary surfactant requires extensive post-translational processing in the secretory pathway, these findings suggest that in secretory cells, such as alveolar type II cells, the UPR is essential for managing the normal physiological ER protein overload that occurs during development. Moreover, failure of this adaptive mechanism may increase pulmonary susceptibility to environmental insults, such as hypoxia and ischemia, ultimately leading to neonatal respiratory failure.Cell Death and Differentiation (2007) 14, 1475–1485; doi:10.1038/sj.cdd.4402151; published online 20 April 2007 [ABSTRACT FROM AUTHOR]

Background and objective: Dynamic balance involving movement of the centre of gravity is important for the evaluation of street fitness after sedation. The purpose of this study was to compare the recovery of dynamic balance after intravenous sedation with propofol or midazolam, and to investigate the usefulness of simple dynamic balance tests in evaluating the recovery. Methods: Fourteen young male volunteers underwent intravenous sedation with propofol and midazolam for 1 h each at an interval of more than 1 week. Computerized dynamic posturography using a multi-axial tilting platform, the 10-m maximum-speed walking test and the timed ‘up & go’ test (subjects stand up from a chair, walk 5 m and back with maximum speed and sit down again) were performed before and after sedation. The increase in each variable of the tests described above represents a reduction of function. Results: The score of the computerized dynamic posturography was significantly lower in propofol sedation than that in mida.zolam sedation until 40 mm after the end of sedation (P = 0.006). The scores of maximum-speed walking test and timed ‘up & go’ test were significantly lower in propofol sedation than those in midazolam sedation till 60 mm after the end of sedation, respectively (P = 0.035 and 0.042). The timed ‘up & go’ and maximum-speed walking tests were well and significantly correlated with computerized dynamic posturography in midazolam sedation (timed ‘up & go’ test vs. computerized dynamic posturography: r = 0.66, P < 0.01; and maximum-speed walking test vs. computerized dynamic posturography: r = 0.53, P < 0.01). Conclusion: The timed ‘up & go’ and maximum-speed walking tests are useful simple dynamic balance tests well correlated with precise computerized dynamic posturography for the evaluation of the recovery of dynamic balance from midazolam sedation in younger adults. [ABSTRACT FROM AUTHOR]

Although in the burning of liquid fuel floating on water the fuel burning itself is similar to that of the simple fuel, the presence of the water underneath introduces a number of effects that are caused by the transfer of heat from the fuel to the water. One of the main effect is the disruptive burning of the fuel known as boilover that is caused by the water boiling and splashing, which results in the explosive burning of the fuel. From a practical point of view, it appears that there are two important aspects of the problem, one is the onset of boilover, the second its intensity. In the present work, the liquid heating is analyzed as a semi-infinite conduction problem with a surface suddenly increased to a constant temperature (boiling point), the penetration of the thermal wave being a function of time (of the order of , where α is the thermal diffusivity of the liquid). This analysis provides predictions for the times at which the nucleation of the water starts (assumed to occur when the water/fuel interface reaches a constant level of superheat ≃120°C). They are in satisfactory agreement with the measurements. These measurements were conducted in two laboratories and address the major issues of the thin layer boilover process by analyzing the effect of the variation of the key parameters of the problem (fuel layer thickness, pool diameter and fuel type). Knowing that the fuel layer remaining before nucleation is closely related to the thickness of the superheated water layer (water that gasifies), it is shown that the boilover intensity can be estimated on the basis of the pre-boilover fuel mass ratio. The thicker these layers, the more intense is the boilover. Fuels used as support of the proposed analysis include single-component fuels and multicomponent fuels. [ABSTRACT FROM AUTHOR]

A computational fluid dynamic model with full coupling between gaseous and liquid phases is developed to predict burning rates of small- to medium-size pool fires. Rates of fuel release are calculated using predictions of flame feedback to the surface of the pool. Favre-averaged Navier-Stokes equations are solved to describe flow in the gaseous phase. Hydrocarbon combustion is described using an eddy breakup model. The heat conduction equation in the region with a regressing surface is solved to model liquid vaporization. A pool fire is modeled as an unsteady process, from the time of ignition until convergence to a quasi-steady burning rate. Comparisons are made to a number of experiments reported in the literature and include burning rates for different fuels, as well as total and radiative flame feedback to the burning surface. [ABSTRACT FROM AUTHOR]

The high-affinity IgE receptor (FcεRI) and the low-affinity IgG receptor (FcγRIII) on mast cells are the key molecules involved in triggering the allergic reaction. These receptors share the common β subunit (FcRβ) which contains an immunoreceptor tyrosine-based activation motif and transduces the signals of these receptors' aggregation. In rodents, FcRβ is essential for the cell surface expression of the FcεRI. In humans, the FcRβ gene was reported to be one of the candidate genes causing atopic diseases. However, the role of FcRβ in vivo still remains ambiguous. To elucidate the functions of FcRβ, we developed the mice lacking FcRβ [FcRβ(-/-)]. The FcRβ(-/-) mice lacked the expression of the FcεRI on mast cells and IgE-mediated passive cutaneous anaphylaxis (PCA) was not induced in FcRβ(-/-) mice as was expected. In these mice, the expression of IgG receptors on mast cells was augmented but the IgG-mediated PCA reaction was attenuated. Although with bone marrow-derived cultured mast cells from FcRβ(-/-), adhesion to fibronectin and Ca2+ flux upon aggregation of IgG receptors were enhanced, mast cells co-cultured with 3T3 fibroblasts exhibited impaired degranulation on receptor aggregation. These observations indicate that FcRβ accelerates the degranulation of mature mast cells via the IgG receptor in connective tissues. [ABSTRACT FROM PUBLISHER]