Role of azaamino acid residue in beta-turn formation and stability in designed peptide.

The structural perturbation induced by C(alpha)-->N(alpha) exchange in azaamino acid-containing peptides was predicted by ab initio calculation of the 6-31G* and 3-21G* levels. The global energy-minimum conformations for model compounds, For-azaXaa-NH2 (Xaa=Gly, Ala, Leu) appeared to be the beta-turn motif with a dihedral angle of phi= +/- 90 degrees, psi=0 degrees. This suggests that incorporation of the azaXaa residue into the i+2 position of designed peptides could stabilize the beta-turn structure. The model azaLeu-containing peptide, Boc-Phe-azaLeu-Ala-OMe, which is predicted to adopt a beta-turn conformation was designed and synthesized in order to experimentally elucidate the role of the azaamino acid residue. Its structural preference in organic solvents was investigated using 1H NMR, molecular modelling and IR spectroscopy. The temperature coefficients of amide protons, the characteristic NOE patterns, the restrained molecular dynamics simulation and IR spectroscopy defined the dihedral angles [ (phi i+1, psi i+1) (phi i+2, psi i+2)] of the Phe-azaLeu fragment in the model peptide, Boc-Phe-azaLeu-Ala-OMe, as [(-59 degrees, 127 degrees) (107 degrees, -4 degrees)]. This solution conformation supports a betaII-turn structural preference in azaLeu-containing peptides as predicted by the quantum chemical calculation. Therefore, intercalation of the azaamino acid residue into the i+2 position in synthetic peptides is expected to provide a stable beta-turn formation, and this could be utilized in the design of new peptidomimetics adopting a beta-turn scaffold.     

Protective Role of miR-34c in Hypoxia by Activating Autophagy through BCL2 Repression

Hypoxia leads to significant cellular stress that has diverse pathological consequences such as cardiovascular diseases and cancers. MicroRNAs (miRNAs) are one of regulators of the adaptive pathway in hypoxia. We identified a hypoxia-induced miRNA, miR-34c, that was significantly upregulated in hypoxic human umbilical cord vein endothelial cells (HUVECs) and in murine blood vessels on day 3 of hindlimb ischemia (HLI). miR-34c directly inhibited BCL2 expression, acting as a toggle switch between apoptosis and autophagy in vitro and in vivo. BCL2 repression by miR-34c activated autophagy, which was evaluated by the expression of LC3-II. Overexpression of miR-34c inhibited apoptosis in HUVEC as well as in a murine model of HLI, and increased cell viability in HUVEC. Importantly, the number of viable cells in the blood vessels following HLI was increased by miR-34c overexpression. Collectively, our findings show that miR-34c plays a protective role in hypoxia, suggesting a novel therapeutic target for hypoxic and ischemic diseases in the blood vessels.     

The role of YKL-40 in the pathogenesis of autoimmune diseases: a comprehensive review

YKL-40, a chitinase-3-like protein 1 (CHI3L1) or human cartilage glycoprotein 39 (HC gp-39), is expressed and secreted by various cell-types including macrophages, chondrocytes, fibroblast-like synovial cells and vascular smooth muscle cells. Its biological function is not well elucidated, but it is speculated to have some connection with inflammatory reactions and autoimmune diseases. Although having important biological roles in autoimmunity, there were only attempts to elucidate relationships of YKL-40 with a single or couple of diseases in the literature. Therefore, in order to analyze the relationship between YKL-40 and the overall diseases, we reviewed 51 articles that discussed the association of YKL-40 with rheumatoid arthritis, psoriasis, systemic lupus erythematosus, Behçet disease and inflammatory bowel disease. Several studies showed that YKL-40 could be assumed as a marker for disease diagnosis, prognosis, disease activity and severity. It is also shown to be involved in response to disease treatment. However, other studies showed controversial results particularly in the case of Behçet disease activity. Therefore, further studies are needed to elucidate the exact role of YKL-40 in autoimmunity and to investigate its potential in therapeutics.     

Development of a Peristaltic Micropump for Bio-Medical Applications Based on Mini LIPCA

This paper presents the design, fabrication, and experimental characterization of a peristaltic micropump. The micropump is composed of two layers fabricated from Polydimethylsiloxane （PDMS） material. The first layer has a rectangular channel and two valve seals. Three rectangular mini lightweight piezo-composite actuators are integrated in the second layer, and used as actuation parts. Two layers are bonded, and covered by two Polymethyl Methacrylate （PMMA） plates, which help increase the stiffness of the micropump. A maximum flow rate of 900μL.min 1 and a maximum backpressure of 1.8 kPa are recorded when water is used as pump liquid. We measured the power consumption of the micropump. The micropump is found to be a promising candidate for bio-medical application due to its bio-compatibility, portability, bidirectionality, and simple effective design.     

阿哈湖深层水中微生物和硫酸还原菌数量及群落结构空间变化

采用荧光原位杂交法分析了贵州阿哈湖深层水环境中总微生物、真细菌和硫酸盐还原菌数量。结果表明:该湖水中微生物总量为1.6×107个.L-1,真细菌占微生物总量的52.9%,且微生物总量和真细菌数量垂直变化无明显差异。随着水体深度的增加,活性微生物数量增加,且微生物的群落结构更加复杂。阿哈湖深层水体中有一定数量的硫酸盐还原菌存在。     

半干旱黄土丘陵区纯林土壤腐殖质异化特征及与其他性质的关系

纯林长期生长或多代连栽必然会导致土壤腐殖质含量和构成发生异化,探究这种异化特征及其与土壤其他性质的关系可以为纯林管理或混交改造提供科学依据。通过对半干旱黄土丘陵区南泥湾林场8种典型纯林土壤腐殖质及其他性质进行系统检测,结果表明:(1)侧柏林土壤腐殖质含量最高(34.61 g/kg),腐殖化程度和稳定性一般;白榆和白桦林土壤的腐殖质含量中等(19.69—23.58 g/kg)、腐殖化程度和稳定性最佳;茶条槭和小叶杨林土壤的腐殖质含量(20.59—22.53 g/kg)和构成均为中等水平;油松、沙棘和刺槐林土壤的腐殖质质量较低(11.77—13.81 g/kg),且腐殖化程度较低,稳定性相对最差;(2)与胡敏酸含量存在显著相互促进作用(P0.05)的土壤性质为CEC、N、微生物量和蛋白酶活性(相关系数0.769—0.926,下同),存在显著相互抑制作用的为有效Cu(-0.793);与富啡酸存在显著相互促进作用的为N、CEC、微生物量、蔗糖酶和磷酸酶活性(0.836—0.955),存在显著相互抑制作用的为有效Cu(-0.822);与胡敏素存在显著相互促进作用的为N、CEC、微生物量、磷酸酶活性和有效Zn(0.766—0.951),存在显著相互抑制作用的为脱氢酶活性(-0.784)。(3)腐殖质构成与其他性质的相关性均不显著(P0.05),其中相对有利于提高胡敏酸/腐殖酸含量之比的土壤性质为蛋白酶、蔗糖酶和过氧化氢酶活性,而不利的是脱氢酶活性;相对有利于提高胡敏酸/富啡酸含量之比的为速效K、CEC和脲酶活性,而不利的是脱氢酶活性。(4)总体而言土壤腐殖质含量较之腐殖质构成与其他性质之间具有更大的相关性;向土壤增施N肥可以促进腐殖质的形成,增加K肥则有利于腐殖质构成的改善,而通过混交改造或增加林下植被是促进纯林土壤腐殖质化过程和解决土壤退化的根本措施。     

Imobilization of β-glucosidase using the cellulose-binding domain of Bacillus subtilis endo-β-1,4-glucanase

A recombinant plasmid pβCBD was constructed for immobilization of Cellulomonas fimi β-glucosidase (Cbg) using the cellulose-binding domain (CBD) of Bacillus subtilis BSE 616 endo-β-1,4-glucanase (Beg). The Cbg-CBD _Beg fusion protein, 80 kDa, was expressed in Escherichia coli and immobilized to Avicel. Cellobiose was completely hydrolyzed with the immobilized fusion protein. The fusion protein bound to Avicel retained full activity during continuous operation for 24 h at 4°C. This revised version was published online in November 2006 with corrections to the Cover Date.     

HO-1 and JAK-2/STAT-1 signals are involved in preferential inhibition of iNOS over COX-2 gene expression by newly synthesized tetrahydroisoquinoline alkaloid, CKD712, in cells activated with lipopolysacchride

We found that CKD712, an S enantiomer of YS49, strongly inhibited inducible nitric oxide synthase (iNOS) and NO induction but showed a weak inhibitory effect on cyclooxygenase-2 (COX-2) and PGE(2) induction in LPS-stimulated RAW 264.7 cells. We, therefore, investigated the molecular mechanism(s) responsible for this by using CKD712 in LPS-activated RAW264.7 cells. Treatment with either SP600125, a specific JNK inhibitor or TPCK, a NF-kappaB inhibitor, but neither ERK inhibitor PD98059 nor p38 inhibitor SB203580, significantly inhibited LPS-mediated iNOS and COX-2 induction. CKD712 inhibited NF-kappaB (p65) activity and translocation but failed to prevent JNK activation. However, AG490, a specific JAK-2/STAT-1 inhibitor, efficiently prevented LPS-mediated iNOS induction but not the induction of COX-2, and CKD712 completely blocked STAT-1 phosphorylation by LPS, suggesting that the NF-kappaB and JAK-2/STAT-1 pathways but not the JNK pathway are important for CKD712 action. Interestingly, CKD712 induced heme oxygenase 1 (HO-1) gene expression in LPS-treated cells. LPS-induced NF-kappaB and STAT-1 activation was partially prevented by HO-1 overexpression. Furthermore, HO-1 siRNA partly reversed not only the LPS-induced NF-kappaB activation and STAT-1 phosphorylation but also inhibition of these actions by CKD 712. Additionally, silencing HO-1 by siRNA prevented CKD712 from inhibiting iNOS expression but not COX-2. When examined plasma NO and PGE(2) levels and iNOS and COX-2 protein levels in lung tissues of mice injected with LPS (10 mg/kg), pretreatment with CKD712 greatly prevented NO and iNOS induction in a dose-dependent manner and slightly affected PGE(2) and COX-2 production as expected. Taken together, we conclude that inhibition of JAK-2/STAT-1 pathways by CKD 712 is critical for the differential inhibition of iNOS and COX-2 by LPS in vitro and in vivo where HO-1 induction also contributes to this by partially modulating JAK-2/STAT-1 pathways.     

Affinity-based proteomics reveal cancer-specific networks coordinated by Hsp90

Most cancers are characterized by multiple molecular alterations, but identification of the key proteins involved in these signaling pathways is currently beyond reach. We show that the inhibitor PU-H71 preferentially targets tumor-enriched Hsp90 complexes and affinity captures Hsp90-dependent oncogenic client proteins. We have used PU-H71 affinity capture to design a proteomic approach that, when combined with bioinformatic pathway analysis, identifies dysregulated signaling networks and key oncoproteins in chronic myeloid leukemia. The identified interactome overlaps with the well-characterized altered proteome in this cancer, indicating that this method can provide global insights into the biology of individual tumors, including primary patient specimens. In addition, we show that this approach can be used to identify previously uncharacterized oncoproteins and mechanisms, potentially leading to new targeted therapies. We further show that the abundance of the PU-H71-enriched Hsp90 species, which is not dictated by Hsp90 expression alone, is predictive of the cell's sensitivity to Hsp90 inhibition.