Fatigue behavior and crack initiation of CAD/CAM resin composite molar crowns

Objective: The aim of this study was to evaluate long-term fatigue behavior using an in vitro step-stress accelerated life test (SSALT), and to determine the crack initiation point using in silico finite element analysis for computer-aided designed and manufactured (CAD/CAM) molar crowns fabricated from three commercial CAD/CAM resin composite blocks: Cerasmart (CS; GC, Tokyo, Japan), Katana Avencia Block (KA; Kuraray Noritake Dental, Niigata, Japan), and Shofu Block HC (HC; Shofu, Kyoto, Japan). Methods: Fifty-one mandibular first molar crowns luted on a resin core die were embedded in acrylic resin and covered with a polyvinyl chloride tube. Single compressive tests were performed for five crowns. SSALT was conducted for 36 crowns using three profiles and reliabilities at 120,000 cycles, and a Weibull analysis was conducted. The maximum principal strain of each CAD/CAM resin composite crown model was analyzed by three-dimensional finite element analysis. Results: Fracture loads of CS and KA (3784 ± 144 N and 3915 ± 313 N) were significantly greater than that of HC (2767 ± 227 N) (p < 0.05). Fracture probabilities at 120,000 cycles were 24.6% (CS), 13.7% (KA), and 14.0% (HC). Maximum principal strain was observed around the mesiolingual cusps of CS and KA and the distobuccal cusp of HC. Significance: CAD/CAM resin composite molar crowns containing nano-fillers with a higher fraction of resin matrix exhibited higher fracture loads and greater longevity, suggesting that these crowns could be used as an alternative to ceramic crowns in terms of fatigue behavior.Yamaguchi S., Kani R., Kawakami K., et al. Fatigue behavior and crack initiation of CAD/CAM resin composite molar crowns. Dental Materials 34, 1578 (2018); https://doi.org/10.1016/j.dental.2018.07.002

A safeguard system for induced pluripotent stem cell-derived rejuvenated T cell therapy

The discovery of induced pluripotent stem cells (iPSCs) has created promising new avenues for therapies in regenerative medicine. However, the tumorigenic potential of undifferentiated iPSCs is a major safety concern for clinical translation. To address this issue, we demonstrated the efficacy of suicide gene therapy by introducing inducible caspase-9 (iC9) into iPSCs. Activation of iC9 with a specific chemical inducer of dimerization (CID) initiates a caspase cascade that eliminates iPSCs and tumors originated from iPSCs. We introduced this iC9/CID safeguard system into a previously reported iPSC-derived, rejuvenated cytotoxic T lymphocyte (rejCTL) therapy model and confirmed that we can generate rejCTLs from iPSCs expressing high levels of iC9 without disturbing antigen-specific killing activity. iC9-expressing rejCTLs exert antitumor effects in vivo. The system efficiently and safely induces apoptosis in these rejCTLs. These results unite to suggest that the iC9/CID safeguard system is a promising tool for future iPSC-mediated approaches to clinical therapy

Targeted reversion of induced pluripotent stem cells from patients with human cleidocranial dysplasia improves bone regeneration in a rat calvarial bone defect model

BackgroundRunt-related transcription factor 2 (RUNX2) haploinsufficiency causes cleidocranial dysplasia (CCD) which is characterized by supernumerary teeth, short stature, clavicular dysplasia, and osteoporosis. At present, as a therapeutic strategy for osteoporosis, mesenchymal stem cell (MSC) transplantation therapy is performed in addition to drug therapy. However, MSC-based therapy for osteoporosis in CCD patients is difficult due to a reduction in the ability of MSCs to differentiate into osteoblasts resulting from impaired RUNX2 function. Here, we investigated whether induced pluripotent stem cells (iPSCs) properly differentiate into osteoblasts after repairing the RUNX2 mutation in iPSCs derived from CCD patients to establish normal iPSCs, and whether engraftment of osteoblasts derived from properly reverted iPSCs results in better regeneration in immunodeficient rat calvarial bone defect models.MethodsTwo cases of CCD patient-derived induced pluripotent stem cells (CCD-iPSCs) were generated using retroviral vectors (OCT3/4, SOX2, KLF4, and c-MYC) or a Sendai virus SeVdp vector (KOSM302L). Reverted iPSCs were established using programmable nucleases, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-derived RNA-guided endonucleases, to correct mutations in CCD-iPSCs. The mRNA expressions of osteoblast-specific markers were analyzed using quantitative reverse-transcriptase polymerase chain reaction. iPSCs-derived osteoblasts were transplanted into rat calvarial bone defects, and bone regeneration was evaluated using microcomputed tomography analysis and histological analysis.ResultsMutation analysis showed that both contained nonsense mutations: one at the very beginning of exon 1 and the other at the initial position of the nuclear matrix-targeting signal. The osteoblasts derived from CCD-iPSCs (CCD-OBs) expressed low levels of several osteoblast differentiation markers, and transplantation of these osteoblasts into calvarial bone defects created in rats with severe combined immunodeficiency showed poor regeneration. However, reverted iPSCs improved the abnormal osteoblast differentiation which resulted in much better engraftment into the rat calvarial bone defect.ConclusionsTaken together, these results demonstrate that patient-specific iPSC technology can not only provide a useful disease model to elucidate the role of RUNX2 in osteoblastic differentiation but also raises the tantalizing prospect that reverted iPSCs might provide a practical medical treatment for CCD

Effect of plastic-type and photocatalyst concentration on plastic film degradation using TIO2

Microplastics, small plastic pieces less than 5 mm in size, are one of the most con- cerning pollutants that can be harmful to the environment and its biota today. Because of their high abundance and small particle size, microplastics are known to be easily ingested by micro organisms and affect many organisms as they move through the food chain. In addition, there is concern that microplastics can be vectors of hazardous substances as they are known to adsorb persistent organic pollutants (POPs) in the environment. However, an efficient treatment method for removing microplastics in wastewater has yet to be established. In recent years, research on introducing photocatalytic o idative degradation systems into wastewater treatment plants (WWTPs) was reported for the potential removal of microplastics from wastewater. Neverthe less, previous reports only focused on developing and evaluating photocatalysts suitable for microplastic degradation, and the e amination of the effects of the types of plastic and photocat alyst concentration on microplastic degradation remains limited. The aim of this study is to eval uate the effect of plastic type and photocatalyst concentration on the degradation of plastic. We used four types of plastic films in the e periment: low-density polyethylene (LDPE), high-den sity polyethylene (HDPE), polypropylene (PP) and polyethylene terephthalate (PET), where the degradation of the plastic was measured by weight. The most used and commercially available TiO2 (P25) was used as a photocatalyst with different concentrations from 0.001 to 1.0 g L-1. The plastic degradation e periment used 3.30 cm squares films with 25 to 30 µm thickness under ultraviolet light irradiation using nine black-light fluorescent lamps (6 W; wavelength: 340-400 nm). The degradation and surface morphology of the plastic film was evaluated by measuring weight loss, carbonyl inde , and scanning electron microscopy. The result showed the LDPE had the highest weight loss compared to other plastic types, which could be due to its simple structure consisting solely of C-H single bonds. Additionally, the highest degradation rate was observed when the photocatalyst concentration was 0.01 g L-1. The reason for the degradation rate decrease at concentrations above 0.01 g L-1 was probably due to the self-light shielding effect of TiO . The low degradation rate at a lower concentration of less than 0.01 g L-1 could be due to insufficient catalyst concentration. In the future, it will be important to analyze the degradation pathways by measuring intermediates during the degrading process for each plastic type.departmental bulletin pape

Movements and Population Structure of Humpback Whales in the North Pacific

Despite the extensive use of photographic identification methods to investigate humpback whales in the North Pacific, few quantitative analyses have been conducted. We report on a comprehensive analysis of interchange in the North Pacific among three wintering regions (Mexico, Hawaii, and Japan) each with two to three subareas, and feeding areas that extended from southern California to the Aleutian Islands. Of the 6,413 identification photographs of humpback whales obtained by 16 independent research groups between 1990 and 1993 and examined for this study, 3,650 photographs were determined to be of suitable quality. A total of 1,241 matches was found by two independent matching teams, identifying 2,712 unique whales in the sample (seen one to five times). Site fidelity was greatest at feeding areas where there was a high rate of resightings in the same area in different years and a low rate of interchange among different areas. Migrations between winter regions and feeding areas did not follow a simple pattern, although highest match rates were found for whales that moved between Hawaii and southeastern Alaska, and between mainland and Baja Mexico and California. Interchange among subareas of the three primary wintering regions was extensive for Hawaii, variable (depending on subareas) for Mexico, and low for Japan and reflected the relative distances among subareas. Interchange among these primary wintering regions was rare. This study provides the first quantitative assessment of the migratory structure of humpback whales in the entire North Pacific basin

The Anti-Aging Potential of Extracts from Chaenomeles sinensis

The Chaenomeles sinensis fruit is used as an effective antitussive agent, analgesic, and diuretic in traditional Chinese medicine. It has been reported that C. sinensis fruit extracts have antimicrobial and anti-inflammatory effects. However, there are very few reports about the effects of C. sinensis extracts on skin. In this study, we investigated the effect of C. sinensis extracts on skin aging. The results of in vitro assays showed that whole fruit extracts of C. sinensis had superoxide dismutase (SOD)-like activity and inhibited the activity of dermal extracellular matrix proteases: Elastase and collagenase. The inhibitory effect of the whole fruit (containing seeds) extract on elastase activity was higher than that of the sarcocarp (seeds removed) extract. Further, the sarcocarp extract showed a higher level of SOD-like activity and a greater inhibitory effect on collagenase activity than the whole fruit extract. In particular, among the three activities studied, the sarcocarp extract showed the most significant inhibitory effect on collagenase activity at low concentrations. The polyphenol-rich fraction obtained from the sarcocarp showed significant collagenase inhibition. Based on these results, we concluded that phenolic compounds from C. sinensis sarcocarp have the potential to protect against skin aging through anti-collagenase activity

Effect of Moisture on the Orientation Birefringence of Cellulose Esters

Orientation birefringence and its wavelength dispersion are studied for hot-drawn films of cellulose esters such as cellulose triacetate (CTA), cellulose diacetate (CDA), and cellulose acetate propionate (CAP) exposed to three different humidities of environments. Hot-drawn CTA films show negative birefringence that decreases with increasing wavelength. On the other hand, CDA and CAP films show positive birefringence that increases with increasing wavelength, i.e., the so-called extraordinary wavelength dispersion of birefringence. Upon exposure to high humidity environment, the orientation birefringence of CDA and CAP decreases. The decrease is prominent for the samples containing a large amount of water. CTA, however, shows an increase in magnitude of its negative orientation birefringence with increasing moisture content. The results can be explained by the increase of the polarizability anisotropy perpendicular to the stretching direction in the cellulose esters. It is found from ATR-FTIR measurements that hydrogen bonds are formed between carbonyl groups of cellulose esters and water molecules. Considering that orientation birefringence of cellulose esters is determined mainly by ester groups, the formation of hydrogen bonds contributes to the polarizability anisotropy, thus affecting the orientation birefringence