Nicotinamide adenine dinucleotide (NAD
) and its reduced form (NADH) are key cofactors serving as essential hydrogen acceptors and donors to facilitate energy and material conversions under mild ...conditions. We demonstrate direct electrochemical conversion to achieve highly efficient regeneration of enzymatically active 1,4-NADH using a Pt-modified TiO
catalyst grown directly on a Ti mesh electrode (Pt-TOT). Spectral analyses revealed that defects formed by the inclusion of Pt species in the lattice of TiO
play a critical role in the regeneration process. In particular, Pt-TOT containing approximately 3 atom% of Pt exhibited unprecedented efficiency in the electrochemical reduction of NAD
at the lowest overpotential to date. This exceptional performance led to the production of active 1,4-NADH with a significantly high yield of 86 ± 3% at -0.6 V
Ag/AgCl (-0.06 V
RHE) and an even higher yield of 99.5 ± 0.4% at a slightly elevated negative potential of -0.8 V
Ag/AgCl (-0.2 V
RHE). Furthermore, the electrochemically generated NADH was directly applied in the enzymatic conversion of pyruvic acid to lactic acid using lactate dehydrogenase.
Tumor progression is a complex process involving extracellular matrix (ECM) remodeling and stiffening. However, the mechanisms that govern these processes and their roles in tumor progression are ...still poorly understood. In this study, we performed bioinformatics, immunohistochemical, and biochemical analyses to examine if collagen cross-linking is associated with tumor stage and regional lymph node metastasis (RLNM) in oral squamous cell carcinoma (OSCC). We found that the genes encoding key enzymes for cross-linking are frequently overexpressed in oral, head, and neck cancers. Specifically, the enzymes lysyl hydroxylase 2 (LH2) or lysyl oxidase (LOX) and LOX-like 2 (LOXL2) were significantly upregulated in late-stage tumors and associated with poor patient prognosis. The protein levels of these enzymes in the primary human OSCC were also significantly increased in late-stage tumors and markedly elevated in the RLNM-positive tumors. Notably, while overall LOX/LOXL2-catalyzed collagen cross-links were enriched in late-stage and RLNM-positive tumors, LH2-mediated stable cross-links were significantly increased. To our knowledge, this is the first study to investigate the association of collagen cross-linking and expression of key enzymes regulating this process with OSCC stage. The data indicate a critical role for collagen cross-linking in OSCC tumor progression and metastasis, which may provide insights into development of novel therapeutic strategies to prevent OSCC progression.
The achievement of a strong and stable bond between composite resin and dentin remains a challenge in restorative dentistry. Over the past two decades, dental materials have been substantially ...improved, with better handling and bonding characteristics. However, little attention has been paid to the contribution of collagen structure/stability to bond strength. We hypothesized that the induction of cross-linking in dentin collagen improves dentin collagen stability and bond strength. This study investigated the effects of glutaraldehyde-and grape seed extract-induced cross-linking on the dentin bond strengths of sound and caries-affected dentin, and on the stability of dentin collagen. Our results demonstrated that the application of chemical cross-linking agents to etched dentin prior to bonding procedures significantly enhanced the dentin bond strengths of caries-affected and sound dentin. Glutaraldehyde and grape seed extract significantly increased dentin collagen stability in sound and caries-affected dentin, likely via distinct mechanisms.
Hydrogen is chemically flexible revealing three aspects; protium (H
0
), proton (H
+
), and hydride (H
-
), which are active toward hydrogenation reactions. While the reactivity of protium is ...characterized by the potential energy at a catalyst surface, electron transfer is of importance as an additional degree of freedom in the reactions with proton and hydride. A promising strategy is to make full use of these active hydrogen species for hydrogenation of stable molecules and achieve chemical transformation of these molecules, which we call “Hydrogenomics”. By reviewing recent studies on the hydrogenation of hydrocarbon, carbon dioxide, dinitrogen, and so on using these active hydrogen species on model metal surfaces, nanoscale electrocatalysts, and multimetallic polyhydride clusters, we discuss the fundamental concepts behind the reactions and possible control of the efficient and selective hydrogenation reactions.
Graphic Abstract
Summary Although recent animal studies have shown that undercarboxylated osteocalcin acts as a hormone regulating glucose metabolism and fat mass, little is known about the relationships in humans. ...We reported here for the first time that undercarboxylated osteocalcin were associated with glucose/fat metabolism in patients with type 2 diabetes. Introduction Recent studies have shown that undercarboxylated osteocalcin (ucOC) acts as a hormone regulating glucose metabolism and fat mass. We investigated the relationship between ucOC as well as other bone turnover markers serum OC, bone-specific alkaline phosphatase (BAP), and urinary N-terminal cross-linked telopeptide of type-I collagen versus serum levels of glucose, fasting serum C-peptide, and adiponectin as well as the amount of fat mass in type 2 diabetes. Methods A total of 180 men and 109 postmenopausal women were consecutively recruited, and radiographic and biochemical characteristics were collected. Fat mass was measured by dual X-ray absorptiometry (DXA) and computed tomography (CT). Results In men, ucOC negatively correlated with percent trunk fat (%trunk fat; by DXA) and visceral/subcutaneous fat ratio (by CT) as well as fasting plasma glucose and HbA₁c (at least p < 0.05). Multiple regression analysis showed that these associations were still significant independent of age, duration of diabetes, body stature, and renal function as well as glucose or fat metabolism, whereas BAP, another bone formation marker, did not correlate with any variable. On the other hand, although ucOC also negatively correlated with %fat and %trunk fat as well as HbA₁c (at least p < 0.05) in postmenopausal women, we found no significant association in multiple regression analysis. Conclusions These findings suggest that ucOC is associated with plasma glucose level and fat mass in men with type 2 diabetes.
Nicotinamide adenine dinucleotide (NAD+) and its reduced form (NADH) are key cofactors serving as essential hydrogen acceptors and donors to facilitate energy and material conversions under mild ...conditions. We demonstrate direct electrochemical conversion to achieve highly efficient regeneration of enzymatically active 1,4-NADH using a Pt-modified TiO2 catalyst grown directly on a Ti mesh electrode (Pt-TOT). Spectral analyses revealed that defects formed by the inclusion of Pt species in the lattice of TiO2 play a critical role in the regeneration process. In particular, Pt-TOT containing approximately 3 atom% of Pt exhibited unprecedented efficiency in the electrochemical reduction of NAD+ at the lowest overpotential to date. This exceptional performance led to the production of active 1,4-NADH with a significantly high yield of 86 ± 3% at −0.6 V vs. Ag/AgCl (−0.06 V vs. RHE) and an even higher yield of 99.5 ± 0.4% at a slightly elevated negative potential of −0.8 V vs. Ag/AgCl (−0.2 V vs. RHE). Furthermore, the electrochemically generated NADH was directly applied in the enzymatic conversion of pyruvic acid to lactic acid using lactate dehydrogenase.
Abstract
The aim of this study was to develop a head–chest phantom that could mimic the physique of a Japanese 0.5-year-old child and to investigate the current status of exposure dose in infant head ...computed tomography examinations in Japan. The phantom was produced by machine processing, and radiophotoluminescence glass dosemeters were installed in the phantom for dose measurement. Organ doses were measured for seven different head scan protocols routinely used in three hospitals. In this study, the average dose of the brain and lens within the scan region was equivalent to that measured using infant phantoms in previous studies. In contrast, the doses of both salivary glands and thyroid glands adjacent to the scan region were 1.4–1.8 times higher than those in previous studies. Expansion of the scan area accompanied by a transition of the scan mode from non-helical to helical may have resulted in the differences in organ doses.
Abstract
In this study, we devised a novel method estimating the bowtie filter shapes by imaging luminescence from a polyethylene terephthalate (PET) resin with X-ray irradiation in a computed ...tomography (CT) scanner. The luminescence distribution of the PET resin corresponding to the thickness of bowtie filter was imaged using a charge-coupled device camera. On the assumption that the material of bowtie filter is aluminium (Al), the shape of bowtie filters was estimated from the correlation between Al attenuation curves and the angular-dependent luminance attenuation profiles according to the thickness of bowtie filters. Dose simulations based on the estimated bowtie filter shapes were performed using head and body PMMA phantoms with 16 and 32 cm in diameter. The simulated values of head and body weighted CT dose index (CTDIw) based on bowtie filter shape by the luminescence imaging method agreed within ~9% with the measured values by a dosemeter.
Data from the radiation monitoring network surrounding the Fukushima Dai-ichi Nuclear Power Plant (FNPP) revealed that the radiation levels generally decayed faster at a highly-contaminated area than ...at neighboring moderately-contaminated areas during the first month after the Fukushima nuclear accident in March, 2011. Two possible mechanisms are considered: secondary transport of radioactive dust by wind or rain, and nonuniform radionuclide ratio of contamination between radioiodine (
131
I) and radiocesium (
134
Cs and
137
Cs). The composition data from soil does not favor the latter scenario, except for the local coastal region south of the FNPP, while inter-regional transport from the highly-contaminated area to the moderately-contaminated areas explains both the general difference in the decay rate in the entire area and the relatively slow decay at a high-dose rate anomaly 40 km northwest of the FNPP.
The Mars Express (MEX) Ion Mass Analyser (IMA) found that the detection rate of the ring-like distribution of protons in the solar wind outside of the bow shock to be quite different between Mars ...orbital summer (around perihelion) and orbital winter (around aphelion) for four Martian years, while the north–south asymmetry is much smaller than the perihelion–aphelion difference. Further analyses using eight years of MEX/IMA solar wind data between 2005 and 2012 has revealed that the detection frequency of the pick-up ions originating from newly ionized exospheric hydrogen with certain flux strongly correlates with the Sun–Mars distance, which changes approximately every two years. Variation due to the solar cycle phase is not distinguishable partly because this effect is masked by the seasonal variation under the MEX capability of plasma measurements. This finding indicates that the variation in solar UV has a major effect on the formation of the pick-up ions, but this is not the only controlling factor.
•First time statistics of pick-up ions upstream of the Martian bow shock.•First time examination of solar-cycle variation of pick-up ions at any planet.•Unexpectedly strong perihelion–aphelion difference in pick-up ions detection.•Solar UV is major but not the only controlling factor to ionize exospheric hydrogen.•Variation due to the solar cycle phase is not distinguishable.
PDF
