Identification of nitroglycerin‐induced cysteine modifications of pro‐matrix metalloproteinase‐9

Nitroglycerin (NTG), an important cardiovascular agent, has been shown recently to activate matrix metalloproteinase‐9 (MMP‐9) in biological systems, possibly leading to destabilization of atherosclerotic plaques. The chemical mechanism for this activation, particularly on the cysteine switch of the pro‐form of MMP‐9 (proMMP‐9), has not been investigated and was examined here using nano‐flow liquid chromatography coupled to mass spectrometry. In order to obtain high sequence coverage, two orthogonal enzymes (trypsin and GluC) were employed to digest the protein in parallel. Two complementary activation methods, collision‐induced dissociation (CID) and electron‐transfer dissociation (ETD), were employed for the identification of various modifications. A high‐resolution Orbitrap analyzer was used to enable confident identification. Incubation of NTG with proMMP‐9 resulted in the formation of an unstable thionitrate intermediate and oxidation of the cysteine switch to sulfinic and irreversible sulfonic acid derivatives. The unstable thionitrate modification was confirmed by both CID and ETD in the proteolytic peptides produced by both trypsin and GluC. Incubation of proMMP‐9 with diethylenetriamine NONOate (a nitric oxide donor) led to sulfonic acid formation, but no observable sulfinic acid modification. Extensive tyrosine nitration by NTG was observed at Tyr‐262, in close proximity to an oxidized Cys‐256 of proMMP‐9. The intramolecular interaction between these two residues toward NTG‐induced oxidation was examined using a synthesized peptide representing the sequence in this domain, PWCSTTANYDTDDR, and the modification status was compared against an analog in which Cys was substituted by Ala. We observed a thionitrate product, extensive Cys oxidative modifications and enhanced tyrosine nitration with the Cys peptide but not with the Ala analog. Our results indicated that neighboring Cys and Tyr residues can facilitate each other's oxidation in the presence of NTG. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation of novel phosphor using intercalation of tobermorite

The emission intensity of phosphors is often subject to concentration quenching after doping of the activator in the host crystal rises above a certain limit. This study describes the preparation of novel phosphors based on tobermorite that do not exhibit concentration quenching. In the preparation of phosphors, Eu³⁺ ions are exchanged with intercalated Ca²⁺ ions within the tobermorite by dipping in EuCl₃ solution. The emission intensity of the Eu³⁺ doped tobermorite increased with increasing Eu/Ca atomic ratio and attained a maximum value of 8.6% for a Eu/Ca atomic ratio of 0.22. Heating of the phosphor at 800 °C resulted in a three-fold improvement in emission intensity.     

Evaluation of cartilage defect at medial femoral condyle in early osteoarthritis of the knee

OBJECTIVE: The purpose of this study was to evaluate cartilage defect at medial femoral condyle on MRI in early osteoarthritis and to compare with early osteoarthritis with meniscal tear without clear cartilage defect. MATERIALS AND METHODS: Twelve patients with medial pain of the knee and cartilage defect without meniscal tear by MRI were studied for cartilage defect. There were two males and 10 females with cartilage defect, and they were between 42 and 61 years of age (average, 51.6). Fifteen patients with medial pain of the knee and meniscal tear and without clear cartilage defect had been studied as meniscal tear cases. There were five males and 10 females with meniscal tear, and they were between 45 and 61 years of age (average 54.5). In both groups, knee injuries by trauma and Kellgren radiographic grade III and IV osteoarthritis were excluded. We compared cartilage defect cases and meniscal tear cases by gender, age, medial meniscus displacement ratio from the edge of the tibial medial joint surface, femorotibial angle (FTA) and Mikulicz line. We measured medial meniscus displacement ratio by the proportion of medial meniscus lesion protruding from the edge of tibial medial joint surface to all the medial meniscus width on MRI. For the evaluation of Mikulicz line, we measured the score by the length from tibial medial joint surface to Mikulicz line to tibial plateau width. chi(2) Test was used for gender, and Mann-Whitney U test was used for age, medial meniscus displacement ratio, FTA and Mikulicz line. RESULTS: Statistically significant difference was not observed between cartilage defect cases and meniscal tear cases for age and gender. Medial meniscus displacement ratio was 13+/-12.3% in cartilage defect cases and 50.4+/-20.1% in meniscal tear cases. Medial meniscus displacement ratio in cartilage defect cases was significantly smaller than in meniscal tear cases (P=.0001). FTA was 174.9+/-2.2 degrees in cartilage defect cases and 178.3+/-4.8 degrees in meniscal tear cases. FTA in cartilage defect cases was significantly smaller than in meniscal tear cases (P=.00390). The score by the length from tibial medial joint surface to Mikulicz line to tibial plateau width was 35.8+/-11.8% in cartilage defect cases and 21.7+/-15.8% in meniscal tear cases. Mikulicz line in cartilage defect cases passes more laterally than in meniscal tear cases significantly (P=.0264). CONCLUSION: In this study, we reported cartilage defect cases at medial femoral condyle in the early osteoarthritis of the knee. We think that these cases were different from early osteoarthritis with meniscal tear in alignment of lower limb and onset mechanism. It is necessary to evaluate meniscus and cartilage in MRI when we diagnose middle-aged patients with medial pain of the knee and without remarkable changes of X-ray.     

Single-step,paper-based concentration and detection of a malaria biomarker

The lateral-flow immunoassay (LFA) is an inexpensive and rapid paper-based assay that can potentially detect infectious disease biomarkers in resource-poor settings. Despite its many advantages that make it suitable for point-of-care diagnosis, LFA is limited by its inferior sensitivity relative to sophisticated laboratory-based assays. Our group previously introduced the use of a micellar aqueous two-phase system (ATPS), comprised of the nonionic Triton X-114 surfactant, to concentrate biomarkers in a sample and enhance their detection with LFA. However, achieving complete phase separation and target concentration using the Triton X-114 system required many hours, and the concentrated sample needed to be manually extracted and applied to LFA. Here, we successfully integrated the concentration and detection steps into a single step that occurs entirely within a portable paper-based diagnostic strip. In a novel approach, we applied the micellar ATPS to a 3-D paper design and effectively reduced the macroscopic phase separation time from 8 h to approximately 3 min. The 3-D design was integrated with LFA to simultaneously concentrate and detect Plasmodium lactate dehydrogenase (pLDH), a malaria biomarker, in both phosphate-buffered saline and fetal bovine serum within 20 min at room temperature. Compared to a conventional LFA setup with a pLDH detection limit of 10 ng μL⁻¹, our single-step diagnostic successfully detected pLDH at 1.0 ng μL⁻¹, demonstrating a 10-fold detection limit improvement and resulting in a sensitive and user-friendly assay that can be used at the point-of-care. The integration of a micellar ATPS and LFA represents a new platform that can improve and promote the use of paper-based diagnostic assays for malaria and other diseases within resource-poor settings.     

Ethylene–propylene copolymerization behavior of ansa‐dimethylsilylene(fluorenyl)(amido)dimethyltitanium complex: Application to ethylene–propylene–diene or ethylene–propylene–norbornene terpolymers

Copolymerization behavior of ethylene (E) and propylene (P) using ansa‐dimethylsilylene(fluorenyl)(amido)dimethyltitanium complex was investigated. P was more reactive than E regardless of the chain‐end monomer unit, which was very unusual in the coordination polymerization system. The terpolymerizations of E, P and norbornene (NB) or 5‐ethylidene‐2‐norbornene (5E2N) were also performed. The each content in the E/P/NB terpolymer was independently controlled by the initial concentration of NB and E/P feed ratio. Glass transition temperature (T_g) of the terpolymer was raised in proportion to the NB content and close to that of the corresponding NB/E random copolymer with the same NB content. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 685–691     

Onion (Allium cepa L.)-Derived Nanoparticles Inhibited LPS-Induced Nitrate Production,However, Their Intracellular Incorporation by Endocytosis Was Not Involved in This Effect on RAW264 Cells

The aim of this study was to evaluate the involvement of nanoparticles prepared from Allium cepa L. as anti-inflammatory agents. In the present study, we identified nanoparticles from Allium cepa L. using the ultracentrifugation exosome purification method. The nanoparticles were referred to as 17,000× g and 200,000× g precipitates, and they contained quercetins, proteins, lipids, and small-sized RNA. The nanoparticles inhibited nitric oxide production from lipopolysaccharide (LPS)-stimulated RAW264 cells without cytotoxic properties. Cellular incorporation was confirmed by laser microscopic observation after PKH26 staining. The inhibition of caveolae-dependent endocytosis and macropinocytosis significantly prevented the incorporation of the nanoparticles but had no effect on the inhibition of nitric oxide in RAW264 cells. Collectively, the identified nanoparticles were capable of inhibiting the LPS response via extracellular mechanisms. Taken together, the way of consuming Allium cepa L. without collapsing the nanoparticles is expected to provide an efficient anti-inflammatory effect.     

Study of photoanode kinetics at metal-free phthalocyanine in an organic p/n bilayer with respect to the pH conditions employed

Using an organic p/n bilayer comprised of 3,4,9,10-perylenetetracarboxyl-bisbenzimidazole (PTCBI, an n-type semiconductor) and 29H,31H-phthalocyanine (H₂Pc, a p-type semiconductor) as a photoanode in the presence of Fe^II(CN)₆^4? (an electron donor), the oxidation kinetics on the H₂Pc surface was investigated with respect to the pHs employed (i.e. pH = 4, 7, and 10). The kinetic analysis of the rate-limiting charge transfer between H₂Pc and Fe^II(CN)₆^4? was conducted by assuming the Langmuir adsorption equilibrium at the H₂Pc/water interface. In addition to a demonstration of the PTCBI/H₂Pc photoanode under the weakly acidic–alkaline conditions, the present work evidently shows that the photoanodic reaction is kinetically independent of the pH conditions employed.     

Pattern-effect-free all-optical wavelength conversion using a hydrogenated amorphous silicon waveguide with ultra-fast carrier decay

Ultra-fast carrier decay, recently discovered in a hydrogenated amorphous silicon waveguide, can be exploited for pattern-effect-free all-optical signal processing based on optical Kerr nonlinearity. In this study, we utilized a 10 Gbit/s RZ-OOK data stream as a pump for degenerate four-wave mixing in a low-loss hydrogenated amorphous silicon waveguide. The propagation loss of the waveguide used was 1.0±0.2 dB/cm at 1550 nm. Unlike crystalline silicon waveguides, no noticeable difference was observed in the BER characteristics between the cases of PRBS 2(7)-1 and 2(31)-1.