Heptanuclear Cadmium Borovanadate Containing a Sandwich-Type Anionic Partial Structure {B20V12} as a Heterogeneous Photocatalyst for the Reduction of CO2 into CH4.

The novel heptanuclear cadmium borovanadate [Cd(en)3]{[Cd(H2O)(en)]6[B20V12O60(OH)2]}·8H2O (en = ethylenediamine) has been prepared under hydrothermal condition. It exhibits a 2D layered architecture that is built up from the [Cd(H2O)(en)]2+ coordination cations and new sandwich-type borovanadate anions [B20V12O60(OH)2]14- constructed by BO3, BO4, BO3(OH), and VO5 units. It features the first heptanuclear cadmium borovanadate containing the single valence of V4+ cations and unique B/V ratio (B/V = 20/12). Its thermal, magnetic, XPS, and optical properties have been systematically studied. The Eg (2.60 eV), EVB (1.69 eV), and ECB (-0.91 eV) were well determined by the UV-vis diffuse reflectance spectrum, UPS curve, and the formula ECB = EVB - Eg, respectively. The photocatalytic experiments revealed that the borovanadate could be selected as an effective and stable heterogeneous catalyst for the reduction of CO2 to CH4 by means of visible light (the amount for CH4 gas could reach 50.57 µmol·g-1·h-1 when the reaction time was 3 h). The recycling experiment and photocatalytic mechanism were also well investigated and established in detail.

Antiplatelet effects of the CEACAM1-derived peptide QDTT.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) restricts platelet activation via platelet collagen receptor GPVI/FcRγ-chain. In this study, screening against collagen-induced platelet aggregation was performed to identify functional CEACAM1 extracellular domain fragments. CEACAM1 fragments, including Ala-substituted peptides, were synthesized. Platelet assays were conducted on healthy donor samples for aggregation, cytotoxicity, adhesion, spreading, and secretion. Mice were used for tail bleeding and FeCl3-induced thrombosis experiments. Clot retraction was assessed using platelet-rich plasma. Extracellular segments of CEACAM1 and A1 domain-derived peptide QDTT were identified, while N, A2, and B domains showed no involvement. QDTT inhibited platelet aggregation. Ala substitution for essential amino acids (Asp139, Thr141, Tyr142, Trp144, and Trp145) in the QDTT sequence abrogated collagen-induced aggregation inhibition. QDTT also suppressed platelet secretion and "inside-out" GP IIb/IIIa activation by convulxin, along with inhibiting PI3K/Akt pathways. QDTT curtailed FeCl3-induced mesenteric thrombosis without significantly prolonging bleeding time, implying the potential of CEACAM1 A1 domain against platelet activation without raising bleeding risk, thus paving the way for novel antiplatelet drugs.

What is the context? The study focuses on Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) and its role in platelet activation, particularly through the GPVI/FcRγ-chain pathway.The research aims to identify specific fragments of CEACAM1's extracellular domain that could restrict platelet activation, without increasing bleeding risk.What is new? The researchers identified a peptide called QDTT derived from the A1 domain of CEACAM1's extracellular segment. This peptide demonstrated the ability to inhibit platelet aggregation, secretion, and GP IIb/IIIa activation.The study also revealed that specific amino acids within the QDTT sequence were essential for its inhibitory effects on collagen-induced aggregation.What is the impact? The findings suggest that the A1 domain-derived peptide QDTT from CEACAM1 could serve as a potential basis for developing novel antiplatelet drugs. This peptide effectively limits platelet activation and aggregation without significantly prolonging bleeding time, indicating a promising approach to managing thrombosis and related disorders while minimizing bleeding risks.

Causal relationship between gut microbiota, plasma metabolites, inflammatory cytokines and abdominal aortic aneurysm: a Mendelian randomization study.

BACKGROUND: Complex interconnections are evident among gut microbiota, circulating metabolites, inflammatory cytokines, and the pathogenesis of abdominal aortic aneurysms (AAA), with the causal dynamics yet to be comprehensively elucidated. The primary objective of this study was to elucidate the potential causal relationships involving gut microbiota-mediated plasma metabolites, inflammatory cytokines, and AAA. METHODS: We utilized data from genome-wide association studies predominantly comprising individuals of European ancestry, encompassing four major gut microbiota signatures, 233 plasma metabolite signatures (N = 136,016), 91 inflammatory cytokine signatures (N = 14,824), and AAA signatures (N = 1,458,875). Mendelian randomization (MR), employed in a two-sample format, was utilized as a tool to investigate the potential causal pathways from gut microbiota to the development of AAA. Additionally, a two-step MR approach was employed to dissect the impact of plasma metabolites and inflammatory cytokines on the relationship between gut microbiota and AAA and to ascertain the mediated fractions. RESULTS: Our findings indicate that five phylum or family-identical bacteria, 175 plasma metabolites, and seven inflammatory factors are causally associated with AAA. Among them, five bacterial species from the same phylum or family, identified from different GWAS data, were strongly associated with AAA. Of these, two exhibited negative causality and three exhibited positive causality. We found that the phylum Firmicutes and the families Oscillospiraceae might reduce the risk of AAA, whereas the families Prevotellaceae, Sutterellaceae, and Aminobacteriaceae might increase the risk of AAA. Further screening indicated that phylum Firmicutes id.1672 (GCST90017114) may confer a protective effect against AAA by reducing triglyceride levels in medium/small high-density lipoprotein (HDL). CONCLUSION: MR analysis has delineated a causal pathway from gut microbiota, through plasma circulating metabolites and inflammatory cytokines, to the pathogenesis of AAA. The role of intestinal flora and certain biomarkers may provide a reference for the diagnosis of AAA, and contribute to the prevention, diagnosis, and treatment of AAA disease.

Improved Catalytic Performance toward Selective Oxidation of Benzyl Alcohols Originated from New Open-Framework Copper Molybdovanadate with a Unique V/Mo Ratio.

A new organic-inorganic hybrid open-framework molybdovanadate with mixed-valences of vanadium (V4+ /V5+ =4/3) and molybdenum (Mo5+ /Mo6+ =8/2) cations has been synthesized. The complex possesses the unique V/Mo ratio (7/10), fascinating 8-C topological network and 1D 4-MR channels (7.793 Å×6.699 Å). Importantly, its catalytic activities for the selective oxidation of benzyl alcohol to benzaldehyde (oxidant: H2 O2 , 30 wt %) have been well evaluated. The results indicated that it exhibited improved catalytic activities (conv.: 96.8 %) compared with the catalyst (Cpyr)5 PV2 Mo5 W5 O40 [conv.: 88.51 %, Cpyr=(C16 H32 C5 H4 N)+ )], high recyclability and structural stability. Moreover, the conversions and selectivities (conv.: 82.4-92.5 %; sele.: 91.5-95.7 %) of the substrates containing electron donating groups (-OH, -CH3 , -OCH3 and -Cl) were significantly higher than those of the substrate containing electron withdrawing group (-NO2 ) (conv. 67.4 %; sele.: 80.8 %). This is due to the fact that the -NO2 with a large Hammett substituent constant is not conducive to the generation of transition state products. The studies revealed the complex could act as a highly efficient heterogeneous catalyst in selective oxidation of benzyl alcohols.

A capacitive humidity sensor based on all-protein embedded with gold nanoparticles @ carbon composite for human respiration detection.

Wool and silk fiber are the most extensive resources of protein fibers and have been used in the textile field for many years. The extracted biocompatible proteins are more and more widely used in flexible devices, sensors, tissue engineering, etc. Here, a fully biomaterial based flexible humidity sensor has been successfully fabricated for the first time. Interdigital electrodes of humidity sensor are printed on a transparent sensor substrate made of silk protein by inkjet printing. The humidity sensitive material is gold nanoparticles hosted nitrogen doped carbon (AuNPs@NC), which is fabricated by in situ dispersion of gold nanoparticles in a wool keratin assisted porous carbon precursor. The best treatment condition of the sensitive materials is obtained by comparing the sensitivity of humidity response. Moreover, the as-prepared biocompatible flexible sensor was successfully used to detect human respiration.

Flexible and disposable gold nanoparticles-N-doped carbon-modified electrochemical sensor for simultaneous detection of dopamine and uric acid.

Catalytic and electrocatalytic applications of supported metal nanoparticles are hindered due to an aggregation of metal nanoparticles and catalytic leaching under harsh operations. Hence, stable and leaching free catalysts with high surface area are extremely desirable but also challenging. Here we report a gold nanoparticles-hosted mesoporous nitrogen doped carbon matrix, which is prepared using bovine serum albumin (BSA) through calcination. BSA plays three roles in this process as a reducing agent, capping agent and carbon precursor, hence the protocol exhibits economic and sustainable. Gold nanoparticles at N-doped BSA carbon (AuNPs@NBSAC)-modified three-electrode strip-based flexible sensor system has been developed, which displayed effective, sensitive and selective for simultaneous detection of uric acid (UA) and dopamine (DA). The AuNPs@NBSAC-modified sensor showed an excellent response toward DA with a linear response throughout the concentration range from 1 to 50 µM and a detection limit of 0.05 µM. It also exhibited an excellent response toward UA, with a wide detection range from 5 to 200 µM as well as a detection limit of 0.1 µM. The findings suggest that the AuNPs@NBSAC nanohybrid reveals promising applications and can be considered as potential electrode materials for development of electrochemical biosensors.

Meso-Reconstruction of Wool Keratin 3D "Molecular Springs" for Tunable Ultra-Sensitive and Highly Recovery Strain Sensors.

Wool keratin (WK) consists of a large number of α-helices, which are just like many molecular-scale springs. Herein, the construction of 3D WK molecular spring networks are reported by cross-linking individual WK molecules via a Michael addition reaction. The as-prepared springs display a superior recovery capability with unusual nonlinear elasticity, very low dissipative energy, and turntable elastic constant achieved by adjusting the chemical crosslinking density of WK networks. Owing to these unique characteristics, the 3D WK networks based flexible strain sensors reveal a high sensitivity, broad sensing ranges, and extremely long and stable performance. While normal highly sensible strain sensors, obtained by highly sophisticated surface or bulk patterning, often exhibit a relatively narrow range of measurements and limited life cycles. Such the WK mediated sensing materials have widespread applications in wearable electronics, such as detection and tracking of different human motions, and even discern voice during speaking.

From Molecular Reconstruction of Mesoscopic Functional Conductive Silk Fibrous Materials to Remote Respiration Monitoring.

Turning insulating silk fibroin materials into conductive ones turns out to be the essential step toward achieving active silk flexible electronics. This work aims to acquire electrically conductive biocompatible fibers of regenerated Bombyx mori silk fibroin (SF) materials based on carbon nanotubes (CNTs) templated nucleation reconstruction of silk fibroin networks. The electronical conductivity of the reconstructed mesoscopic functional fibers can be tuned by the density of the incorporated CNTs. It follows that the hybrid fibers experience an abrupt increase in conductivity when exceeding the percolation threshold of CNTs >35 wt%, which leads to the highest conductivity of 638.9 S m-1 among organic-carbon-based hybrid fibers, and 8 times higher than the best available materials of the similar types. In addition, the silk-CNT mesoscopic hybrid materials achieve some new functionalities, i.e., humidity-responsive conductivity, which is attributed to the coupling of the humidity inducing cyclic contraction of SFs and the conductivity of CNTs. The silk-CNT materials, as a type of biocompatible electronic functional fibrous material for pressure and electric response humidity sensing, are further fabricated into a smart facial mask to implement respiration condition monitoring for remote diagnosis and medication.

Programing Performance of Silk Fibroin Superstrong Scaffolds by Mesoscopic Regulation among Hierarchical Structures.

To design higher-strength natural scaffold materials, wool keratin (WK) rich in α-helix structures is used as a well-defined foreign substrate, which induces the formation of ß-crystallites in silk fibroin (SF). Consequently, the macroscopic properties of silk materials (such as the rheological properties of SF hydrogels and the mechanical properties of stents) can be manipulated by governing the change in the hierarchical mesoscopic structure of silk materials. In this work, by monitoring the structure and morphology in the SF gel process, the mechanism of the effect of keratin on SF network formation was speculated, which was further used to design ultra-high-strength protein scaffolds. It has been confirmed that WK accelerates the gelation of SF by reducing the multistep nucleation barrier and increasing the primary nucleation sites, and then establishing a high-density SF domain network. The modulus of the protein composite scaffold prepared by this facile strategy can reach 11.55 MPa, and the MC-3T3 cells can grow well on the scaffold surface. The results suggest that freeze-dried biocompatible SF-based scaffolds are potential candidates for bone tissue engineering.

CEACAM1 Inhibited IκB-α/NF-κB Signal Pathway Via Targeting MMP-9/TIMP-1 Axis in Diabetic Atherosclerosis.

Atherosclerosis (AS) is the most common and serious complication in type 2 diabetes mellitus (T2DM). Recent studies have emphasized that inflammation is the main cause of atherosclerosis. Studies have shown that carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1) regulates the expression of matrix metallopeptidase 9 (MMP-9) after ischemic stroke to reduce inflammation. The aim of this study was to elucidate potential molecular mechanism of CEACAM1 on the inflammatory response in atherosclerosis. The serum levels of CEACAM1, MMP-9, and tissue inhibitors of metalloproteinase 1 (TIMP-1) in T2DM patients and healthy control was detected. The results showed that the levels of CEACAM1 and TIMP-1 were significantly decreased, and the levels of MMP-9 were significantly higher than those in the control group. Moreover, we also observed the effect of CEACAM1 on atherosclerosis in T2DM rats. Hematoxylin & eosin (HE) staining and oil red staining showed that CEACAM1 recombinant protein reduced intima-media thickness and the area of atherosclerotic plaques. To further explore the molecular mechanism of CEACAM1 regulating MMP-9/TIMP-1, we conducted experiments in rat aorta vascular endothelial cells and rat aorta smooth muscle cells. The result showed that CEACAM1 inhibits inflammatory response via MMP-9/TIMP-1 axis. Taken together, CEACAM1 attenuates diabetic atherosclerosis by inhibition of IκB/NF-κB signal pathway via MMP-9/TIMP-1 axis, which indicate that CEACAM1 is potentially amenable to therapeutic manipulation for clinical application in atherosclerosis in T2DM.

The CEACAM1-derived peptide QLSN impairs collagen-induced human platelet activation through glycoprotein VI.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) regulates collagen-mediated platelet activation through its cytoplasmic immunoreceptor tyrosine-based inhibition motifs (ITIMs). However, the function of CEACAM1's extracellular cleavage fragments is currently unknown. In the present study, we used mass spectrometry (MS) to identify 9 cleavage fragments shed by matrix metallopeptidase 12 (MMP-12), and then we synthesized peptides with sequences corresponding to the fragments. QLSNGNRTLT (QLSN), a peptide from the A1-domain of CEACAM1, significantly attenuated collagen-induced platelet aggregation. QLSN also attenuated platelet static adhesion to collagen. Additionally, QLSN reduced human platelet secretion and integrin αIIbß3 activation in response to glycoprotein VI (GPVI)-selective agonist, convulxin. Correspondingly, QLSN treatment significantly decreased convulxin-mediated phosphorylation of Src, protein kinase B (Akt), spleen tyrosine kinase (Syk) and phospholipase Cγ2 (PLCγ2) in human platelets. These data indicate that the CEACAM1-derived peptide QLSN inhibits GPVI-mediated human platelet activation. QLSN could potentially be developed as a novel antiplatelet agent.

Silk Composite Electronic Textile Sensor for High Space Precision 2D Combo Temperature-Pressure Sensing.

Wearable electronic textiles based on natural biocompatible/biodegradable materials have attracted great attention due to applications in health care and smart clothes. Silkworm fibers are durable, good heat conductors, insulating, and biocompatible, and are therefore regarded as excellent mediating materials for flexible electronics. In this paper, a strategy on the design and fabrication of highly flexible multimode electronic textiles (E-textile) based on functionalized silkworm fiber coiled yarns and weaving technology is presented. To achieve enhanced temperature sensing performance, a mixture of carbon nanotubes and an ionic liquid ([EMIM]Tf2 N) is embedded, which displays top sensitivity of 1.23% °C-1 and stability compared with others. Furthermore, fibrous pressure sensing based on the capacitance change of each cross-point of two yarns gives rise to highly position dependent and sensitivity sensing of 0.136 kPa-1 . Based on weaving technologies, a unique combo textile sensor, which can sense temperature and pressure independently with a position precision of 1 mm2 , is obtained. The application to intelligent gloves endows the position dependent sensing of the weight, and temperature distribution sensing of the temperature.

Efficacy and safety of left atrial appendage closure in non-valvular atrial fibrillation in patients over 75 years.

Percutaneous left atrial appendage closure (LAAC) may decrease risks of stroke and bleeding in elderly patients with non-valvular atrial fibrillation (NVAF), but it is still lacking of evidence. The present study aimed at evaluating the efficacy and safety of LAAC in patients with NVAF over 75 years. 351 patients with NVAF who underwent LAAC were retrospectively analyzed on the LAAC procedure characteristics and the clinical follow-up according to age (age ≥ 75 years or < 75 years). Out of the 351 patients, LAA were successfully closed in 347 patients (98.9%), including 341 with Watchman (WM) device and 6 with Amplatzer cardiac plug (ACP) device because of the WM device-incompatible anatomy. There were no significant differences in total LAAC success rate and procedure-related major complications within 7 days between the groups aged ≥ 75 years and aged < 75 years. After a nearly 2-year follow-up, there was an increased trend of major bleedings and all bleedings in the group aged ≥ 75 years, but there were no significant differences between both groups in all-cause death, cardiovascular death, stroke/TIA/system embolism, device thrombus and device gap (> 5 mm). Kaplan-Meier analysis revealed that the relative risk of annual thromboembolic events between the observed values and the expected ones based on CHA2DS2-VASc score in the group aged ≥ 75 years decreased more obviously (61.9% vs. 54.3%); however, the relative risk of bleedings between the observed values and the expected ones based on HAS-BLED score in the younger group aged < 75 years decreased more significantly (59.6% vs. 29.2%). LAAC in patients with advanced age (age ≥ 75 years), has the same level of efficacy, safety and feasibility as in the younger patients aged < 75 years. Thus, LAAC may be an ideal choice to prevent stroke in NVAF patients with advanced age.

Platelet Carcinoembryonic Antigen Cell Adhesion Molecule 5 (CEACAM5) as a Possible Novel Diagnostic Tool for Evaluation of Acute Coronary Syndrome.

BACKGROUND Acute coronary syndrome (ACS) occurs approximately every 40 seconds, and was an underlying cause of death in 1 out of every 7 deaths. More accurate indicators are needed to distinguish patients with ACS from patients manifesting negative changes in electrocardiogram (ECG) and myocardial enzymes. This study aimed to investigate whether the expression of platelet carcinoembryonic antigen cell adhesion molecule-5 (CEACAM5/CEA/CD66e) could help predict ACS. MATERIAL AND METHODS We enrolled 82 participants (mean age 60 years, 33 females and 49 males). The expression of CEA on washed human platelets was assessed using two-color flow cytometry. The CEA levels on platelets and in serum of these 82 consecutive patients were detected using two-color whole-blood flow cytometry analysis and a custom-made Luminex multiplex assay, respectively. RESULTS CEA was expressed on the surface of human platelets. The expression of platelet CEA (P<0.01), but not serum CEA (P=0.30), was significantly higher in patients with ACS compared to patients with normal coronary artery. Increased platelet CEA levels could serve as a new independent indicator for ACS (P=0.0003). Platelet CEA testing (P=0.000002), as well as cardiac troponin I (cTnI) (P=0.0005), can diagnose ACS with high sensitivity and specificity, and, combined with cTnI (P<0.0001), can improve the diagnostic value. CONCLUSIONS Platelet CEA expression was higher in individuals presenting with ACS. Hence, platelet CEA might be a novel and reliable biomarker for ACS. Large-scale studies are needed to confirm this hypothesis.

Association of matrix metalloprotease 1, 3, and 12 polymorphisms with rheumatic heart disease in a Chinese Han population.

BACKGROUND: Rheumatic heart disease (RHD) is an autoimmune disease triggered by acute rheumatic fever (ARF). Matrix metalloproteinases (MMPs) play an important role in the modulation of immune responses. The purpose of this study was to evaluate the association of MMP1, 3, and 12 promoter polymorphisms with RHD in a Han population in Southern China since the 3 genes are localized on the same chromosome and have a combined effect. METHODS: DNA samples were obtained from 90 adult patients with RHD and 90 control subjects. Polymorphisms in MMP1 (rs1799750), MMP3 (rs3025058), and MMP12 (rs2276109) were genotyped by direct sequencing. Differences in genotype and allele frequencies of these polymorphisms were compared between the cases and the controls using Unconditional logistic regression models and Chi-squared test. RESULTS: The 2G/2G genotype of rs1799750 in MMP1 was associated with a significantly higher risk of RHD when compared with the 1G/1G genotype (OR = 3.227; 95% CI:1.118-9.31; p = 0.03). The frequency of allele 2G was higher in patients with RHD compared to the controls (69.4% vs. 58.9%; p = 0.048) No significant differences in genotype and allele frequencies of rs3025058 in MMP3 and rs2276109 in MMP12 were found between the patients with RHD and the controls (p > 0.05). CONCLUSIONS: Our results suggest that rs1799750 in MMP1 might be a risk factor for RHD in a Han population in Southern China, and individuals carrying the 2G/2G genotype are likely more susceptible to RHD. In contrast, rs3025058 in MMP3 and rs2276109 in MMP12 might not contribute to the risk of developing RHD in this population. Further studies with larger samples and other ethnic populations are required to confirm these findings.

Ultrastable, highly luminescent quantum dot composites based on advanced surface manipulation strategy for flexible lighting-emitting.

Although quantum dots (QDs) have remarkable potential application in flexible light emitting diodes (LED), the loss of solvent-protected QDs leads to low quantum yield (QY) and poor stability, severely restricting the development. Flexible QD LEDs (Q-LEDs) with three primary colors were fabricated by mixing CdS/ZnS, CdSe@ZnS/ZnS, and CdSe/CdS QDs with polydimethylsiloxane (PDMS) by in situ hydrosilylation based surface manipulation strategy, which endows the device with highly ultrastable and luminescent performance. The surface manipulation strategy mainly includes the control of solvent dosage, purification times of QDs, concentration of QDs in PDMS, and oxidation on the preparation process of the QDs and PDMS composites. The highest QY of CdSe@ZnS/ZnS-PDMS composite is 82.03%, higher than the QY (80%) of the QD solution. After UV bleaching, organic solvents (acetone, ethanol and water), and heating treatment, the QYs of the QDs and PDMS maintain a high value, manifesting their good stability. Q-LED hybrid light-emitting devices were further fabricated by a molding technique demonstrating satisfied current and thermal stability. Flexible Q-LEDs can be expended to other shapes, such as fibers and blocks, indicating the huge potential of QD-polymer composites for light sources and displays etc.

Matrix metalloproteinase12 facilitated platelet activation by shedding carcinoembryonic antigen related cell adhesion molecule1.

Platelets express several MMPs that modulate their activation, which in turn regulates thrombosis, but the exact mechanism is unclear. This study evaluated the platelet expression of MMP12 and platelet activation by shedding CEACAM1 mediated by MMP12. Expression of MMP12 was measured by RT-PCR, Western blot (WB), and casein zymography in platelet from whole blood by gel filtration over plateletpheresis. The site of CEACAM1 cleavage by MMP12 was determined by high performance liquid chromatography (HPLC), mass spectrometry, WB and flow cytometry (FCM). Furthermore, the regulation of platelet aggregation, release and adhesion by MMP12-dependent shedding of platelet CEACAM1 was analyzed. We have observed that human platelets express MMP12. In addition, CEACAM1 as enzymatic substrates of MMP12 have also been found in this study. MMP12 can cleave the CEACAM1 exodomain at several sites and generated several short peptides. Among these fragments, one peptide, WYKG was identified, whose cutting sits were S66/W67 and A83/I84. We also found that MMP12 facilitated type I collagen induced platelet aggregation, adhesion and alpha granule secretion. Similarly, one short peptide, WYKG, facilitated type I collagen induced platelet alpha granule secretion. We conclude that platelet express MMP12 may facilitate platelet activation through shedding of CEACAM1.

Effect of the Solvent Temperatures on Dynamics of Serine Protease Proteinase K.

To obtain detailed information about the effect of the solvent temperatures on protein dynamics, multiple long molecular dynamics (MD) simulations of serine protease proteinase K with the solute and solvent coupled to different temperatures (either 300 or 180 K) have been performed. Comparative analyses demonstrate that the internal flexibility and mobility of proteinase K are strongly dependent on the solvent temperatures but weakly on the protein temperatures. The constructed free energy landscapes (FELs) at the high solvent temperatures exhibit a more rugged surface, broader spanning range, and higher minimum free energy level than do those at the low solvent temperatures. Comparison between the dynamic hydrogen bond (HB) numbers reveals that the high solvent temperatures intensify the competitive HB interactions between water molecules and protein surface atoms, and this in turn exacerbates the competitive HB interactions between protein internal atoms, thus enhancing the conformational flexibility and facilitating the collective motions of the protein. A refined FEL model was proposed to explain the role of the solvent mobility in facilitating the cascade amplification of microscopic motions of atoms and atomic groups into the global collective motions of the protein.

Engineering of fluorescent emission of silk fibroin composite materials by material assembly.

This novel materials assembly technology endows the designated materials with additional/enhanced performance by fixing "functional components" into the materials. Such functional components are molecularly recognized and accommodated by the designated materials. In this regard, two-photon fluorescence (TPF) organic molecules and CdTe quantum dots (QDs) are adopted as functional components to functionalize silk fibers and films. TPF organic molecules, such as, 2,7-bis[2-(4-nitrophenyl) ethenyl]-9,9-dibutylfluorene (NM), exhibit TPF emission quenching because of the molecular stacking that leads to aggregation in the solid form. The specific recognition between -NO2 in the annealed fluorescent molecules and the -NH groups in the silk fibroin molecules decouples the aggregated molecules. This gives rise to a significant increase in the TPF quantum yields of the silk fibers. Similarly, as another type of functional components, CdTe quantum dots (QDs) with different sizes were also adopted in the silk functionalization method. Compared to QDs in solution the fluorescence properties of functionalized silk materials display a long stability at room temperature. As the functional materials are well dispersed at high quantum yields in the biocompatible silk a TPF microscope can be used to pursue 3D high-resolution imaging in real time of the TPF-silk scaffold.

Expression of matrix metalloproteinase-12 in aortic dissection.

BACKGROUND: Aortic dissection(AD) is an acute process of large blood vessels characterized by dangerous pathogenic conditions and high disability and high mortality. The pathogenesis of AD remains debated. Matrix metalloproteinase-12 (MMP-12) participates in many pathological processes such as abdominal aortic aneurysm, atherosclerosis, emphysema and cancer. However, this elastase has rarely been assessed in the presence of AD. The aim of the present study was to investigate the expression of MMP-12 in aortic tissue so as to offer a better understanding of the possible mechanisms of AD. METHODS: The protein expression levels of MMP-12 were analyzed and compared in aorta tissue and the blood serum samples by reverse transcription polymerase chain reaction(RT-PCR), Western blotting, immuno-histochemistry, fluorescence resonance energy transfer ( FRET ) activity assay and enzyme-linked immuno sorbent assay ( ELISA ), respectively. Ascending aorta tissue specimens were obtained from 12 patients with an acute Stanford A-dissection at the time of aortic replacement, and from 4 patients with coronary artery disease (CAD) undergoing coronary artery bypass surgery. Meanwhile, serum samples were harvested from 15 patients with an acute Stanford A-dissection and 10 healthy individuals who served as the control group. RESULTS: MMP-12 activity could be detected in both AD and CAD groups, but the level in the AD group was higher than those in the CAD group (P < 0.05). MMP-12 proteolysis existed in both serum samples of the AD and healthy groups, and the activity level in the AD group was clearly higher than in the healthy group (P < 0.05). For AD patients, MMP-12 activity in serum was higher than in the aorta wall (P < 0.05). MMP-12 activity in the aortic wall tissue can be inhibited by MMP inhibitor v (P < 0.05). CONCLUSION: The present study directly demonstrates that MMP-12 proteolytic activity exists within the aorta specimens and blood samples from aortic dissection patients. MMP-12 might be of potential relevance as a clinically diagnostic tool and therapeutic target in vascular injury and repair.