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1.
Med Sci Monit ; 26: e919300, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31949123

RESUMO

BACKGROUND The aim of the present study was to investigate the clinical predictive value of pre-infarction angina (PIA) combined with mean platelet volume to lymphocyte count ratio (MPVLR) for no-reflow phenomenon and short-term mortality in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI). MATERIAL AND METHODS A total of 1009 STEMI patients who had undergone PCI were enrolled and subdivided into 4 groups based on the occurrence of PIA and the presence of MPVLR above or below the cutoff value. Analysis of the predictors of the no-reflow phenomenon and 90-day mortality was conducted. Further, evaluation and comparison of the clinical predictive value of PIA, MPVLR, and their combination were done. RESULTS Both MPVLR (odds ratio [OR]=1.476, 95% confidence interval [CI]: 1.401 to 1.756, P<0.001; hazard ratio [HR]=1.430, 95% CI: 1.287 to 1.643, P<0.001) and PIA (OR=0.905, 95% CI: 0.783 to 0.986, P<0.001; HR=0.878, 95% CI: 0.796 to 0.948, P<0.001) were independent predictors of no-reflow phenomenon and 90-day mortality. Spearman's rank correlation test revealed that MPVLR (r=-0.297, P<0.001), monocyte to lymphocyte count ratio (MLR) (r=-0.211, P<0.001) and neutrophil to lymphocyte count ratio (NLR) (r=-0.389, P<0.001) in peripheral blood were significantly negatively correlated with postoperative left ventricular ejection fraction (LVEF). Upon comparing the area under curve (AUC), the MPVLR combined with PIA achieved better performance in differentiating no-reflow phenomenon (AUC=0.847, 95% CI: 0.821 to 0.874) and 90-day mortality (AUC=0.790, 95% CI: 0.725 to 0.855), than the GRACE score, MPVLR and PIA alone, and had similar performance to all other pairwise combinations of the GRACE score, MPVLR and PIA. CONCLUSIONS High MPVLR and PIA were independent predictors of the no-reflow phenomenon and 90-day mortality in patients with STEMI after PCI. Moreover, Combined application of MPVLR and PIA can effectively predict the occurrence of the no-reflow phenomenon and 90-day mortality.

2.
ACS Appl Mater Interfaces ; 12(2): 2346-2353, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31877012

RESUMO

The development of advanced anode materials is crucial to enhance the performance of sodium-ion batteries (SIBs). In this study, SnSe2 nanoparticles chemically embedded in a carbon shell (SnSe2@C) were fabricated from Sn-organic frameworks and evaluated as an anode material for SIBs. The structural characterization demonstrated that there existed C-Sn chemical bonds between the SnSe2 nanoparticles and carbon shell, which could strongly anchor SnSe2 nanoparticles to the carbon shell. Such a structure can not only facilitate charge transfer but also ensure the structural stability of the SnSe2@C electrode. In addition, the carbon shell also helped in the dispersion of SnSe2 nanoparticles, thus offering more redox-active sites for Na+ storage. The as-prepared SnSe2@C nanocomposite could deliver good cycling stability and a superior rate capability of 324 mA h g-1 at 2 A g-1 for SIBs.

3.
Biomater Sci ; 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31821399

RESUMO

Hepatocellular carcinoma (HCC) patients suffer from severe pain due to the serious systemic side effects and low efficiency of chemotherapeutic drugs, and it is important to develop novel drug delivery systems to circumvent these issues. In this study, a series of galactose-based glycopolymers, poly(N-(prop-2-enoyl)-ß-d-galactopyranosylamine)-b-poly(N-isopropyl acrylamide) (pGal(OH)-b-pNIPAA), were prepared through a sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and tetrabutylammonium hydroxide (TBAOH)-mediated removal of acetyl groups. Hydrophilic doxorubicin hydrochloride was introduced to undergo collaborative assembly with poly(N-(prop-2-enoyl)-ß-d-peracetylated galactosamine)-b-poly(N-isopropyl acrylamide) (pGal(Ac)-b-pNIPAA) via TBAOH treatment. pGal-b-pNIPAA/doxorubicin (DOX) delivery nanoparticles (GND NPs) formed by collaborative assembly were fully characterized by NMR, TEM and FT-IR, indicating the well-controlled formation of particles with uniform size and high efficiency in terms of drug loading and encapsulation compared with conventional adsorption methods. Meanwhile, the GND NPs were observed to be rapidly disintegrated under acidic conditions and resulted in an increased release of DOX. Cellular experiments showed that pGal-b-pNIPAA/DOX is apparently an asialoglycoprotein receptor (ASGPR)-mediated target of HCC, resulting in enhanced cellular uptake to HepG2 cells and anti-tumor efficacy in vitro. Furthermore, GND NPs III exerted more sustainable and effective anti-tumor effects compared to free DOX on a transgenic zebrafish TO(KrasG12V) model in vivo. These results indicated that the biocompatible nanomaterials developed by collaborative assembly with galactosyl diblock glycopolymers and DOX may serve as a promising candidates for targeting therapy of HCC.

4.
Mol Carcinog ; 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31793078

RESUMO

Circular RNAs (circRNAs) are involved in the regulation of gene expression in different physiological and pathological processes. These macromolecules can act as microRNA (miRNA) sponges and play an important role as gene regulators throughout the circRNA-miRNA pathway. In this study, we established a radioresistance model with the nasopharyngeal carcinoma cell line CNE-2, and then analyzed the differences in the circRNAs between radioresistant and normal nasopharyngeal carcinoma cell lines using a high-throughput microarray. Tested circRNAs included 1042 upregulated and 1558 downregulated circRNAs. Relevant signaling pathways associated with the circRNAs and their target miRNAs were analyzed using bioinformatics analysis to determine the radioresistance of the differentially expressed circRNAs. Curcumin was used to treat irradiated cell lines, and changes in the circRNA before and after curcumin treatment were analyzed to investigate the radiosensitization effects of curcumin. The results showed that curcumin could regulate the circRNA-miRNA-messenger RNA network and inhibit the epidermal growth factor receptor (EGFR), signal transducers and activators of transcription 3 (STAT3), and growth factor receptor-bound protein 2 (GRB2) to achieve radiosensitization. Thus, circRNA acted as a miRNA sponge and regulated the expression of miRNA, thereby affecting EGFR, STAT3, and GRB2 expression and radiosensitization.

5.
Environ Sci Technol ; 2019 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-31834792

RESUMO

Black carbon (BC) emissions from the Canadian oil sands (OS) surface mining facilities in Alberta were investigated using aircraft measurements. BC emission rates were derived with a top-down mass balance approach, and were found to be linearly related to the volume of oil sands ore mined at each facility. Two emission factors were determined from the measurements. Production-based BC emission factors were in the range of 0.6 to 1.7 g/tonne mined OS ore, whereas fuel based BC emission factors were between 95 and 190 mg/kg-fuel, depending upon the facility. The annual BC emission, at 707 ± 117 tonnes/year for the facilities, was determined using the production based emission factors and annual production data. Although this annual emission is in reasonable agreement with the BC annual emissions reported in the latest version of the Canadian national BC inventory (within 16%), the relative split between off road diesel and stack sources is significantly different between the measurements and the inventory. This measurement evidence highlights the fact that the stack sources of BC may be overestimated and the off road diesel sources may be underestimated in the inventory, and points to the need for improved BC emission data from diesel sources within facilities.

6.
Artigo em Inglês | MEDLINE | ID: mdl-31881117

RESUMO

Metal-organic frameworks (MOFs) are considered as promising materials with fascinating properties. Their widespread applications are sometimes hindered by intrinsic instability of frameworks. However, like a coin has two sides, the instability of MOFs can also be employed for decent utilizations. Here, we report a concept of taking MOFs as metal ion precursors for constructing functional nanocomposites by utilizing the instability of MOFs. The heterogeneous growth process of nanostructures on substrates involves releasing of metal ions, nucleating on substrates and forming covering structure. Specifically, the synthesized CoS with carbon nanotubes as substrates display enhanced performance in lithium-ion battery. Such strategy not only develops a new view for exploiting the instability of MOFs, but also supplies a potential prospect for designing versatile functional nanocomposites.

7.
Huan Jing Ke Xue ; 40(6): 2793-2799, 2019 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854672

RESUMO

In the research, an anaerobic membrane bioreactor (AnMBR) was used to treat simulated salty organic wastewater, and the effect of salinity on reactor performance and membrane fouling properties was investigated. The results indicated that when the influent salinity increased gradually but was lower than 9.1 g·L-1, the reactor ran stably and the effluent performance was good. When the salinity increased to 10 g·L-1, the COD removal-efficiency, gas production, and methane content decreased significantly; meanwhile, the sludge concentration, sludge volume index (SVI), soluble microbial products (SMP), and extracellular polymeric substance (EPS) levels became elevated at first and then declined with the rising salinity. The system developed compact flocs and a high settling ability. The hollow fiber membrane module was run for three cycles in 118 d. The membrane operating cycle was extended from 31 d to 48 d with the increasing salinity, which favored the control of membrane fouling. SEM-EDX analysis results revealed that there were similar crystalline substances in the film membrane foulants, and Na, Mg, Al, Si, Cl, K, Ca, and Fe were the main inorganic elements. Excitation emission matrix (EEM) analysis results demonstrated that proteins and humic acids were the main components of the organic membrane foulants.


Assuntos
Reatores Biológicos , Membranas Artificiais , Salinidade , Eliminação de Resíduos Líquidos , Águas Residuárias , Anaerobiose , Reatores Biológicos/microbiologia , Matriz Extracelular de Substâncias Poliméricas , Substâncias Húmicas , Proteínas , Esgotos
8.
Environ Sci Technol ; 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31751130

RESUMO

Oil sands (OS) are an important type of heavy oil deposit, for which operations in Alberta, Canada, were recently found to be a large source of secondary organic aerosol (SOA). However, SOA formation from the OS mining, processing, and subsequent tailings, especially in the presence of NOx, remains unclear. Here, photooxidation experiments for OS-related precursors under high-NOx conditions were performed using an oxidation flow reactor, in which ∼95% of peroxy radicals (RO2) react with NO. The SOA yields under high-NOx conditions were found to be lower than yields under low-NOx conditions for all precursors, which is likely due to the higher volatilities of the products from the RO2 + NO pathway compared with RO2 + HO2. The SOA yields under high-NOx conditions show a strong dependence on pre-existing surface area (not observed in previous low-NOx experiments), again attributed to the higher product volatilities. Comparing the mass spectra of SOA formed from different precursors, we conclude that the fraction of m/z > 80 (F80) can be used as a parameter to separate different types of SOA in the region. In addition, particle-phase organic nitrate was found to be an important component (9-23%) of OS SOA formed under high-NOx conditions. These results have implications for better understanding the atmospheric processing of OS emissions.

9.
Environ Sci Technol ; 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31756294

RESUMO

The environmental risks and health impacts associated with particulate organophosphate flame retardants (OPFRs), which are ubiquitous in the global atmosphere, have not been adequately assessed due to the lack of data on the reaction kinetics, products, and toxicity associated with their atmospheric transformations. Here, the importance of such transformations for OPFRs are explored by investigating the reaction kinetics, degradation chemical mechanisms, and toxicological evolution of two OPFRs (2-ethylhexyl diphenyl phosphate (EHDP) and diphenyl phosphate (DPhP)) coated on (NH4)2SO4 particles upon heterogeneous OH oxidation. The derived reaction rate constants for the heterogeneous loss of EHDP and DPhP are (1.12 ± 0.22) × 10-12 and (2.33 ± 0.14) × 10-12 cm3 molecules-1 s-1, respectively. Using recently developed real-time particle chemical composition measurements, particulate products from heterogeneous photooxidation and the associated degradation mechanisms for particulate OPFRs are reported for the first time. Subsequent cytotoxicity analysis of the unreacted and oxidized OPFR particles indicated that the overall particle cytotoxicity was reduced by up to 94% with heterogeneous photooxidation, likely due to a significantly lower cytotoxicity associated with the oxidized OPFR products relative to the parent OPFRs. The present work not only provides guidance for future field sampling for the detection of transformation products of OPFRs, but also strongly supports the ongoing risk assessment of these emerging chemicals and most critically, their products.

10.
Opt Express ; 27(20): 27459-27476, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31684512

RESUMO

The ray-optics (RO) model is a reasonable method to calculate optical force in geometrical optics regime. However, the RO model fails to calculate the optical force produced by diffractive optical field and other arbitrary structured light beams. We propose the Fourier ray (FR) method to calculate the optical force for arbitrary incident beams. Combining the Fourier optics and the geometrical optics, the FRs are defined as rays that inlay on the plane waves weighted by the Fourier angular spectrum of the incident beam. According to traditional RO model and FR method, we can analyze optical forces on a microsphere immersed in various beams. To validate the FR method, forces of the fundamental Gaussian beam and Airy beam are respectively calculated and compared with traditional method. In addition, optical forces in three arbitrary structured light beams are demonstrated as well. Our simulations show that the FR method is able to evaluate the optical forces generated by diffractive optical field and complex structured light beams, and give a solid prediction of their trapping performances. In RO regime, the Fourier ray method is a universal method to predict the interaction between bead and complex optical field.

11.
Cell Death Dis ; 10(10): 752, 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31582742

RESUMO

Long non-coding RNAs (lncRNAs) have been suggested as important regulators of cancer development and progression in hepatocellular carcinoma (HCC). Nevertheless, the clinical value and biological roles of LINC00978 in HCC remain unclear. In this study, we detected the expression of LINC00978 in tumor tissues and serum of HCC patients, examined the roles of LINC00978 in HCC progression and elucidated the underlying molecular mechanisms. We found that LINC00978 expression was upregulated in tumor tissues and serum of HCC patients. Higher serum levels of LINC00978 could distinguish HCC patients from hepatitis and liver cirrhosis patients and healthy controls. LINC00978 knockdown inhibited HCC cell proliferation, migration and invasion while promoted cell cycle arrest and apoptosis. Overexpression of LINC00978 led to the opposite effects. LINC00978 knockdown also inhibited HCC growth and metastasis in mouse tumor models. Mechanistically, LINC00978 bound to EZH2 and mediated its accumulation at the promoter region of p21 and E-cadherin genes, leading to the trimethylation of H27K3 and the inhibition of p21 and E-cadherin expression. Moreover, the simultaneous depletion of p21 and E-cadherin expression reversed the inhibitory effects of LINC00978 knockdown on HCC cell proliferation, migration, and invasion. Taken together, these findings suggest that LINC00978 promotes HCC progression by inhibiting p21 and E-cadherin expression via EZH2-mediated epigenetic silencing. LINC00978 may represent a novel biomarker for HCC diagnosis, prognosis, and therapy.

12.
Lab Chip ; 19(23): 3974-3978, 2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31659359

RESUMO

Carbon dots with different emission fluorescence have a great number of potential applications for various areas from in vitro imaging and biotherapy, due to the good biosafety of red fluorescent CDs, to efficient ion detection and photocatalysis, due to the excellent photoluminescence properties of blue fluorescent carbon dots. Traditional methods for the synthesis of full-spectrum carbon dots require 24 h of synthesis and complex column chromatography. In this paper, a facile and efficient microfluidic method to continuously synthesize small and uniform carbon dots with full-spectrum emission fluorescence is developed for the first time. The synthesis process could be reduced to 20 minutes. Through XPS analysis and DFT calculations, it is quantitatively revealed that the number of primary amino groups determines the energy gap of the carbon dots and thus determines the fluorescence emission wavelength of the carbon dots. Applications for precise Fe3+ detection and in vitro bio-imaging were successfully implemented, showing great potential application value of the carbon dots.

13.
Brain Behav ; 9(9): e01369, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31397082

RESUMO

OBJECTIVES: Interleukin-33, a newly identified member of interleukin-1 family, had been confirmed to play a crucial role in regulating inflammatory responses in various disease. However, the exact role of interleukin-33 in the disease process of acute ischemic stroke still remains unclear. This study aims to demonstrate the relationship between interleukin-33 levels and long-term functional outcome as well as ischemic stroke recurrence. METHODS: Three hundred and four first-ever acute ischemic stroke patients were recruited and basic information and history of all subjects taken within 72 hr on admission. The functional outcome was estimated by Barthel index. The multivariate logistic regression was used to analyze the prognosis, while the Cox proportional hazard model was applied to assess the recurrence risk. RESULTS: Out of 304 subjects, 259 patients successfully completed scheduled two-year follow-up. We found that higher interleukin-33 levels correlated positively with better prognosis as compared with those with lower interleukin-33 levels who presented with poorer outcome (62.45 ± 20.50 ng/ml vs. 51.58 ± 19.16 ng/ml, p < .001). After adjustment of all confounders, interleukin-33 was associated with the one-year prognosis with an adjusted odds ratio of 0.956 (95% confidence interval, 0.937-0.976, p < .001). Furthermore, interleukin-33 levels were also closely related to recurrent ischemic stroke with an adjusted hazard ratio of 0.979 (95% confidence interval, 0.961-0.997, p = .025). CONCLUSIONS: IL-33 can be used to predict the long-term outcomes and ischemic stroke recurrence in first-ever acute ischemic stroke patients.

14.
Angew Chem Int Ed Engl ; 58(38): 13584-13589, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31329345

RESUMO

Although sodium ion batteries (SIBs) possess many beneficial features, their rate performance, cycling stability, and safety need improvement for commercial applications. Based on the mechanisms of the sodium ions storage in carbon materials, herein we present a multiple active sites decorated amorphous carbon (MAC) with rich structural defects and heteroatom doping as an anode material for SIBs. The full utilization of fast bonding-debonding processes between the active sites and sodium ions could bring a capacitive strategy to achieve superior sodium storage properties. Consequently, after materials characterization and electrochemical evaluation, the as-prepared electrode could deliver high rate and long-life performance. This active-site-related design could be extended to other types of electrode materials, thereby contributing to future practical SIB applications.

15.
Environ Pollut ; 252(Pt B): 1902-1909, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31227346

RESUMO

Inhalation exposure to flame retardants used as additives to minimize fire risk and plasticizers is ubiquitous in human daily activities, but has not been adequately assessed. To address this research gap, the present study conducted an assessment of human health risk for four age groups through inhalation exposure to size fractionated particle-bound and gaseous halogenated flame retardants (polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs)) and organophosphate esters (OPEs) at indoor and outdoor environments (school, office, and residence) in three districts of a megacity (Guangzhou, China). Results demonstrated that OPEs were the dominant components among all targets. Indoor daily intakes of PBDEs and OPEs were 13-16 times greater than outdoor levels for all age groups. Gaseous OPEs contributed significantly greater than particle-bound compounds to daily intakes of all target compounds. Based on the different life scenarios, hazard quotient (HQ) and incremental life cancer risk (ILCR) from adults exposure to PBDEs and OPEs in indoor and outdoor settings were the greatest, followed by adolescents, children, and seniors. The estimated HQ and ILCR for all age groups both indoors and outdoors were lower than the safe level (HQ = 1 and ILCR = 10-6), indicating that the potential health risk for local residents in Guangzhou via inhalation exposure to atmospheric halogenated flame retardants and OPEs was low.


Assuntos
Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Exposição por Inalação/efeitos adversos , Exposição por Inalação/análise , Organofosfatos/análise , Plastificantes/análise , Adolescente , Adulto , Poluição do Ar em Ambientes Fechados/análise , Criança , China , Gases , Habitação , Humanos , Pessoa de Meia-Idade , Medição de Risco , Adulto Jovem
16.
Environ Pollut ; 252(Pt A): 236-244, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31153028

RESUMO

Current air quality models usually underestimate the concentration of ambient air sulfate, but the cause of this underestimation remains unclear. One reason for the underestimation is that the sulfate formation mechanism in the models is incomplete, and does not adequately consider the impact of the synergistic effects of high concentrations of multiple pollutants on sulfate formation. In this work, the roles of gaseous NO2, NH3 and solution ionic strength in the formation of sulfate in the aqueous phase were quantitatively investigated using a glass reactor and a 30 m3 smog chamber, separately. The results showed that sulfate formation was enhanced to different degrees in the presence of gas-phase NO2, NH3 and their coexistence as solutes in both liquid solution and aerosol water. NH3 enhances the aqueous oxidation of SO2 by NO2 mainly by accelerating the uptake of SO2 through increased solubility. More importantly, we found that high ionic strength in aerosol water could significantly accelerate the aqueous oxidation of SO2, resulting in unexpectedly high S(VI) formation rates. We estimate that under severe haze conditions, heterogeneous oxidation of SO2 by NO2 on aerosols may be much shorter than that through gas phase oxidation by OH, aided by high ionic strengths in aerosols. Considering the existence of complex air pollution conditions with high concentrations of NO2, NH3 and aerosol water, as expected in typical urban and suburban settings, the sulfate formation mechanisms revealed in the present work should be incorporated into air quality models to improve the prediction of sulfate concentrations.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Amônia/química , Monitoramento Ambiental/métodos , Nitritos/química , Sulfatos/análise , Dióxido de Enxofre/química , Aerossóis/análise , Concentração Osmolar , Oxirredução , Material Particulado/análise , Solubilidade , Sulfatos/química , Água
17.
Environ Sci Technol ; 53(12): 6794-6803, 2019 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-31117542

RESUMO

The current uncertainties in the reactivity and atmospheric persistence of particle-associated chemicals present a challenge for the prediction of long-range transport and deposition of emerging chemicals such as organophosphate flame retardants, which are ubiquitous in the global environment. Here, the OH-initiated heterogeneous oxidation kinetics of organophosphate flame retardants (OPFRs) coated on inert (NH4)2SO4 and redox-active FeSO4 particles were systematically determined as a function of relative humidity (RH). The derived reaction rate constants for the heterogeneous loss of tricresyl phosphate (TCP; kTCP) and tris(2-butoxyethyl) phosphate (TBEP; kTBEP) were in the range of (2.69-3.57) × 10-12 and (3.06-5.55) × 10-12 cm3 molecules-1 s-1, respectively, depending on the RH and coexisting Fe(II) content. The kTCP (coated on (NH4)2SO4) was relatively constant over the investigated RH range while kTBEP was enhanced by up to 19% with increasing RH. For both OPFRs, the presence of Fe(II) enhanced their k by up to 53% over inert (NH4)2SO4. These enhancement effects (RH and Fe(II)) were attributed to fundamental changes in the organic phase state (higher RH lowered particle viscosity) and Fenton-type chemistry which resulted in the formation of reactive oxygen species, respectively. Such findings serve to emphasize the importance of ambient RH, the phase state of particle-bound organics in general, and the presence of coexisting metallic species for an accurate description of the degradation kinetics and aging of particulate OPFRs in models used to evaluate their atmospheric persistence.


Assuntos
Retardadores de Chama , Umidade , Ferro , Organofosfatos , Oxirredução
18.
Exp Eye Res ; 184: 258-265, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31077713

RESUMO

PURPOSE: The occurrence of presbyopia and cataract is closely related to changes in the mechanical properties of the crystalline lens. There are no established methods so far for in vivo assessment. By introducing ultrasound elastography, we proposed group velocity (Vg) of an induced shear wave as a new biomarker to characterize the mechanical properties of the lens in our previous study. Here, we investigated the effect of the ultrasound frequency on measurement accuracy and validated the results with a conventional ex vivo compression testing. We also demonstrated a change trend in Vg and its correlation with age in a rabbit model. METHODS: Eight New Zealand white rabbits were fed normally from the fourth to seventh month. An ultrasound elastography system was developed to measure Vgin vivo on every eye once per month. The performances when using a high-frequency (L22-11v) and low-frequency (L11-4v) probe were compared. Rabbits were sacrificed after in vivo measurements by the end of the seventh month and this was followed by ex vivo ultrasound measurements and conventional compression tests on the extracted lenses. RESULTS: The results demonstrated that there were no significance differences in Vg between measurements with high-frequency (USE-HF) and low-frequency (USE-LF) probes in the same month-age group. The mean Vg and the standard deviation of four rabbits that were 7 months old were 2.37 ±â€¯0.24  m/s, 2.36 ±â€¯0.25 m/s, 2.43 ±â€¯0.26 m/s and 2.44 ±â€¯0.38 m/s, with USE-HF for ex vivo and in vivo measurements and USE-LF for ex vivo and in vivo measurements, respectively. There were no significant differences (p > 0.05) and they were all in agreement with the results of compression tests, which was 16.16 ±â€¯1.84 kPa in Young's modulus. The results also showed that Vg increased with age. In combination with the results of our previous study, Vg showed a relatively sharp increase from 2 to 5 months, while it had a slight increase from 5 to 7 months. CONCLUSIONS: The USE-HF and USE-LF has comparable accuracy in Vg measurements while USE-HF had an advantage regarding better spatial resolution. The change trend of Vg was in accord with the growth phase of New Zealand white rabbits, which usually results in sexual maturity at 5 months old. This implies that Vg can be used as a biomarker parameter for evaluating the mechanical properties of the lens undergoing physiological changes.

19.
Carbohydr Polym ; 217: 232-239, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31079681

RESUMO

Heparan sulfate (HS) and heparin, representative members of the glycosaminoglycans, possess distinct biological functions in terms of their specific interactions with hundreds of binding proteins. However, the structural properties of HS and heparin are complex due to their variable repeating motifs, different chain lengths and sulfation patterns. A concise chemoenzymatic approach has been developed to obtain well-defined low molecular weight (LMW) HS analogues. Pasteurella multocida heparosan synthase-2 (PmHS2) was utilized to fabricate the HS backbones with controllable chain lengths ranging from 14mer to 26mer. Moreover, regioselective and overall sulfation were conducted by chemical approach. The persulfated HS analogues exhibited more potent beta-site amyloid precursor protein (APP)-cleaving enzyme-1 (BACE-1) inhibitory activity than heparin and enoxaparin, and enhanced BACE-1 inhibitions were also found with the increasing molecular size of the HS analogues. This approach supplies the promising LMW HS analogues for the potential development of novel anti-Alzheimer's drugs.


Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Heparitina Sulfato/análogos & derivados , Inibidores de Proteases/química , Sequência de Carboidratos , Glicosiltransferases/química , Heparitina Sulfato/síntese química , Humanos , Peso Molecular , Pasteurella multocida/enzimologia , Inibidores de Proteases/síntese química
20.
Nat Commun ; 10(1): 1863, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-31015411

RESUMO

The oil and gas (O&G) sector represents a large source of greenhouse gas (GHG) emissions globally. However, estimates of O&G emissions rely upon bottom-up approaches, and are rarely evaluated through atmospheric measurements. Here, we use aircraft measurements over the Canadian oil sands (OS) to derive the first top-down, measurement-based determination of the their annual CO2 emissions and intensities. The results indicate that CO2 emission intensities for OS facilities are 13-123% larger than those estimated using publically available data. This leads to 64% higher annual GHG emissions from surface mining operations, and 30% higher overall OS GHG emissions (17 Mt) compared to that reported by industry, despite emissions reporting which uses the most up to date and recommended bottom-up approaches. Given the similarity in bottom-up reporting methods across the entire O&G sector, these results suggest that O&G CO2 emissions inventory data may be more uncertain than previously considered.

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