Compositional and histological comparison of carbonate apatite fabricated by dissolution–precipitation reaction and Bio-Oss<Superscript>®</Superscript>

Carbonate apatite (CO₃Ap) is an inorganic component of bone. This study aimed to compare the composition and tissue response to of CO₃Ap (CO₃Ap-DP) fabricated by the dissolution–precipitation reaction using calcite as a precursor and Bio-Oss®, which is widely used in orthopedic and dental fields as a synthetic bone substitute. X-ray diffraction and Fourier transform infrared results showed that CO₃Ap-DP and Bio-Oss® were both B-type carbonate apatite with low crystallinity. The average sizes of CO₃Ap-DP and Bio-Oss® granules were 450?±?58 and 667?±?168μ?m, respectively, and their carbonate contents were 12.1?±?0.6 and 5.6?±?0.1?wt%, respectively. CO₃Ap-DP had a larger amount of CO₃ than Bio-Oss® but higher crystallinity than Bio-Oss®. When a bone defect made at the femur of rabbits was reconstructed with CO₃Ap-DP and Bio-Oss®, CO₃Ap-DP granules were partially replaced with bone, whereas Bio-Oss® remained at 8 weeks after implantation. CO₃Ap-DP granules elicited a significantly larger amount of new bone formation at the cortical bone portion than Bio-Oss® at 4 weeks after the implantation. The results obtained in the present study demonstrated that CO₃Ap-DP and Bio-Oss® showed different behavior even though they were both classified as CO₃Ap. The CO₃ content in CO₃Ap played a more important role than the crystallinity of CO₃Ap for replacement to bone and high osteoconductivity.

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Antioxidant activity of Magnolol, honokiol, and related phenolic compounds

The antioxidant activity of 10 Japanese and Chinese crude drugs (Kampo drugs) was determined in vitro. Extract of Magnolia cortex, which had the highest antioxidant activity, contained phenolic compounds magnolol and honokiol. However, inhibitory effects of these compounds on lipid oxidation were weaker than that of α-tocopherol as measured by thiobarbituric acid assay. The structure-activity relationship of phenolic compounds showed that antioxidant activities were in the order 4-allyl-2,6-dimethoxyphenol ≥ p,p′-biphenol > eugenol > 2-allyl-6-methylphenol > honokiol > magnolol > caffeic acid > p-ethylphenol > guaiacol. As expected, these results showed that an electron donor and/or bulky groups at the ortho- or para-position of the phenol were required for inhibition of lipid oxidation. Electron spin resonance spin trapping experiments showed that phenol compounds with an allyl substituent on their aromatic rings directly scavenged superoxide (O ₂ ⁻ ), and that only eugenol trapped hydroxyl radicals. These findings suggest that phenolic compounds that contain allyl groups may be effective antioxidants because of the scavenging ability of O ₂ ⁻ or hydroxyl radical, whereas other phenols, without an allyl moiety such as α-tocopherol, may play a role in the termination of free radical chain reactions.     

Preparation of modified styrene-divinylbenzene copolymers having different physical structures and their adsorption characteristics of nonionic surfactants

Several α-oxoethylated and α-hydroxyethylated styrene-divinylbenzene (St-DVB) resins having different degrees of crosslinking and porosity were prepared and their adsorption behaviour toward a nonionic surfactant, decaethyleneglycol nonylphenyl monoether, was investigated. The increment of the adsorption capacity caused by the introduction of the α-hydroxyethyl groups was remarkable in the less crosslinked resin. The α-hydroxyethylated resin derived from the St-DVB resin synthesized with 10 vol.-% DVB and 100 – 120 vol.-% of 2,2,4-trimethylpentane showed the highest capacity among the resins tested. The significance of both macroporosity and gel porosity in the effective adsorption of the nonionic surfactant was elucidated. A column operation using proposed resins was carried out and versatility was evaluated in terms of the breakthrough capacity.     

Is the Efficiency of RNA Silencing Evolutionarily Regulated?

Small interfering RNAs (siRNAs) and microRNAs (miRNAs) regulate gene expression in a sequence-specific manner. Genes with partial complementarity to siRNA/miRNA sequences in their 3′-untranslated regions (UTRs) are suppressed by a mechanism referred to as the siRNA off-target effect or miRNA-mediated RNA silencing. However, the determinants of such RNA silencing efficiency are poorly understood. Previously, I and co-workers reported that the efficiency of RNA silencing is strongly correlated with the thermodynamic stability of base pairing in the duplex formed within an siRNA/miRNA and between the seed region and its target mRNA. In this review, I first summarize our previous studies that identified the thermodynamic parameter to estimate the silencing efficiency using the calculated base pairing stability: siRNAs downregulate the expression of off-target genes depending on the stability of binding between the siRNA seed region (nucleotides 2–8) and off-target mRNAs, and miRNAs downregulate target mRNA expression depending on the stability of the duplex formed between the 5′ terminus of the miRNA and its target mRNA. I further discuss the possibility that such thermodynamic features of silencing efficiency may have arisen during evolution with increasing body temperature in various organisms.     

Germline Whole-Gene Deletion of FH Diagnosed from Tumor Profiling

Hereditary leiomyomatosis and renal cell carcinoma (HL (RCC)) entails cutaneous and uterine leiomyomatosis with aggressive type 2 papillary RCC-like histology. HLRCC is caused by pathogenic variants in the FH gene, which encodes fumarate hydratase (FH). Here, we describe an episode of young-onset RCC caused by a genomic FH deletion that was diagnosed via clinical sequencing. A 35-year-old woman was diagnosed with RCC and multiple metastases: histopathological analyses supported a diagnosis of FH-deficient RCC. Although the patient had neither skin tumors nor a family history of HLRCC, an aggressive clinical course at her age and pathological diagnosis of FH-deficient RCC suggested a germline FH variant. After counseling, the patient provided written informed consent for germline genetic testing. She was simultaneously subjected to paired tumor profiling tests targeting the exome to identify a therapeutic target. Although conventional germline sequencing did not detect FH variants, exome sequencing revealed a heterozygous germline FH deletion. As such, paired tumor profiling, not conventional sequencing, was required to identify this genetic deletion. RCC caused by a germline FH deletion has hitherto not been described in Japan, and the FH deletion detected in this patient was presumed to be of maternal European origin. Although the genotype-phenotype correlation in HLRCC-related tumors is unclear, the patient’s family was advised to undergo genetic counseling to consider additional RCC screening.     

Long‐term changes in Japanese women's facial skin color

It has been suggested that skin color changes not only with advancing age but also with the times. The purpose of this study was to investigate changes in Japanese women's facial skin color over 25 years, as well as the changes in skin pigmentation that affect skin color. First, skin color changes in terms of Munsell color values were investigated. A total of 3181 Japanese women residing in the greater Tokyo area were enrolled, and datasets were collected using spectrophotometers, designated as the 1991, 2001, 2005, and 2015 data. The mean Munsell hue, value, and chroma were calculated for each measurement year. Next, the concentrations of melanin and hemoglobin were calculated from spectral data, to investigate changes in skin pigmentations. Finally, Monte Carlo simulations were performed to verify that the suggested changes in skin pigmentations brought about skin color changes. As a result, skin color significantly changed toward high lightness, low saturation, and high yellowness from the 1991 data to the 2001 data. From the 2005 to 2015 data, the skin color distribution shifted toward lower saturation and increased redness. In addition, the concentration of hemoglobin decreased significantly from the 1991 data to the 2001 data, while the melanin concentration decreased significantly from the 2005 data to the 2015 data.     

Comparison of Macro and Microtribological Property of Molybdenum Disulfide Film Exposed to LEO Space Environment

Macro- and microtribological properties of the MoS₂ film exposed to atomic oxygen, ultraviolet rays and radiation both in low earth orbit (LEO) and in ground-based facility were evaluated relevance to micro/nano satellites. MoS₂ samples are exposed to LEO space environment by the space environment exposure device experiment on international space station. Laser-detonation atomic oxygen beam source was used for atomic oxygen simulation on the ground. X-ray photoelectron spectroscopy and energy dispersive spectroscopy measurements suggested that electron beam and ultraviolet exposure did not affect chemical structure of MoS₂ surfaces. However, atomic oxygen-exposed and flight samples showed surface oxidation. It was found that the macroscopic friction coefficient of the flight sample was similar to that of the control sample. In contrast, remarkable increase in friction coefficient in microscopic properties was observed.     

Oral sustained delivery of paracetamol from in situ gelling xyloglucan formulations

The purpose of this study was to evaluate the potential of a xyloglucan formulation with in situ gelling properties for the oral sustained delivery of paracetamol. Gelation of dilute aqueous solutions of the polysaccharide xyloglucan occurred in rabbit and rat stomachs as the orally administered chilled solutions attained body temperature. In vitro studies demonstrated diffusion-controlled release of paracetamol from the gels over a period of 6 hr. The bioavailabilities of paracetamol from the xyloglucan gels formed in situ in the stomachs of rabbits after oral administration of the liquid formulations were similar to that of a commercially available suspension containing an identical dose of paracetamol.     

Titanium Fiber Plates for Bone Tissue Repair

Titanium plates are widely used in clinical settings because of their high bone affinity. However, owing to their high elastic modulus, these plates are not suitable for bone repair since their proximity to the bone surface for prolonged periods can cause stress shielding, leading to bone embrittlement. In contrast, titanium fiber plates prepared by molding titanium fibers into plates by simultaneously applying compression and shear stress at normal room temperature can have an elastic modulus similar to that of bone cortex, and stress shielding will not occur even when the plate lies flush against the bone's surface. Titanium fibers can form a porous structure suitable for cell adhesion and as a bone repair scaffold. A titanium fiber plate is combined with osteoblasts and shown that the titanium fiber plate is better able to facilitate bone tissue repair than the conventional titanium plate when implanted in rat bone defects. Capable of being used in close contact with bone for a long time, and even capable of promoting bone repair, titanium fiber plates have a wide range of applications, and are expected to make great contributions to clinical management of increasing bone diseases, including bone fracture repair and bone regenerative medicine.