Ginsenoside Rb1 Prevents H2O2-Induced HUVEC Senescence by Stimulating Sirtuin-1 Pathway

We have previously reported that Ginsenoside Rb1 may effectively prevent HUVECs from senescence, however, the detailed mechanism has not demonstrated up to now. Recent studies have shown that sirtuin-1 (Sirt1) plays an important role in the development of endothelial senescence. The purpose of this study was to explore whether Sirt1 is involved in the action of Ginsenoside Rb1 regarding protection against H2O2-induced HUVEC Senescence.Senescence induced by hydrogen peroxide (H2O2) in human umbilical vein endothelial cells (HUVECs) was examined by analyzing plasminogen activator inhibitor-1 (PAI-1) expression, cell morphology, and senescence-associated beta-galactosidase (SA-β-gal) activity. The results revealed that 42% of control-treated HUVECs were SA-β-gal positive after treatment by 60 µmol/L H2O2, however, this particular effect of H2O2 was decreased more than 2-fold (19%) in the HUVECs when pretreated with Rb1 (20 µmol/L) for 30 min. Additionally, Rb1 decreased eNOS acetylation, as well as promoted more NO production that was accompanied by an increase in Sirt1 expression. Furthermore, upon knocking down Sirt1, the effect of Rb1 on HUVEC senescence was blunted.The present study indicated that Ginsenoside Rb1 acts through stimulating Sirt1 in order to protect against endothelial senescence and dysfunction. As such, Sirt1 appears to be of particular importance in maintaining endothelial functions and delaying vascular aging

Cloning and Characterization of Genes Involved in Nostoxanthin Biosynthesis of Sphingomonas elodea ATCC 31461

Most Sphingomonas species synthesize the yellow carotenoid nostoxanthin. However, the carotenoid biosynthetic pathway of these species remains unclear. In this study, we cloned and characterized a carotenoid biosynthesis gene cluster containing four carotenogenic genes (crtG, crtY, crtI and crtB) and a β-carotene hydroxylase gene (crtZ) located outside the cluster, from the gellan-gum producing bacterium Sphingomonas elodea ATCC 31461. Each of these genes was inactivated, and the biochemical function of each gene was confirmed based on chromatographic and spectroscopic analysis of the intermediates accumulated in the knockout mutants. Moreover, the crtG gene encoding the 2,2′-β-hydroxylase and the crtZ gene encoding the β-carotene hydroxylase, both responsible for hydroxylation of β-carotene, were confirmed by complementation studies using Escherichia coli producing different carotenoids. Expression of crtG in zeaxanthin and β-carotene accumulating E. coli cells resulted in the formation of nostoxanthin and 2,2′-dihydroxy-β-carotene, respectively. Based on these results, a biochemical pathway for synthesis of nostoxanthin in S. elodea ATCC 31461 is proposed

Involvement of Flavonoids from the Leaves of Carya cathayensis Sarg. in Sirtuin 1 Expression in HUVEC Senescence

Atherosclerosis is the commonest cause of death in the world and one of the most important processes that occurs with increasing age because it is accompanied by progressive endothelial dysfunction. Recent studies demonstrated that Sirtuin 1 (SIRT1) might potentially affect cell senescence. However, the effect of SIRT1 on the regulation of human umbilical vein endothelial cell (HUVEC) senescence with total flavonoids (TFs) has not been addressed previously. This study investigated how SIRT1 functions in the process of HUVEC senescence when TFs are present and identified the potential molecular mechanisms involved. Using a model of HUVEC senescence induced by angiotensin II, TFs pretreatment reduced the percentage of senescence-associated β-galactosidase (SA-β-gal) cells and p53 mRNA expression. The level of SIRT1 protein and E2F1 decreased during HUVEC senescence and could be partially recovered when cells were coincubated with TFs, while the levels of proteins p53 and p21 increased during cell senescence and diminished in response to the TFs treatment. When coincubated with 20 mM nicotinamide, the results with SA-β-gal-positive cells and the expression of SIRT1, E2F1, p53, and p21 were contrary to that obtained with only TFs pretreatment. The data indicate that the TFs exert their effect on HUVEC senescence through SIRT1

Wave-Induced Instantaneous Liquefaction of a Non-Cohesive Seabed around Buried Pipelines: A Liquefaction-Associated Non-Darcy Flow Model Approach

In complex marine environments, the wave-induced instantaneous liquefaction of the seabed is a key issue for the long-term safety control of marine structures. Existing computational frameworks for instantaneous liquefaction result in unreasonable tensile stresses in a non-cohesive seabed. To address this issue, a liquefaction-associated non-Darcy flow model has been proposed, but it has only been applied to the scenario of a pure seabed without a structure. In this study, we applied the previously proposed non-Darcy flow model to investigate the mechanism of wave-seabed-structure interactions under extreme wave loading considering a pipeline fully buried in a non-cohesive seabed. By comparing the liquefaction depths in the presence and absence of structures, it was found that the existence of structures weakens the attenuation of the pore pressure amplitude and influences the overall pore pressure distribution. Parametric studies were conducted. It was found that the liquefaction depth from the non-Darcy model is approximately 0.73 times that from the traditional Darcy model, regardless of whether or not a pipeline is involved. A quantitative relationship between the wave loading and structural size was established. The liquefied zone above the buried pipeline was found to be smaller than that in a pure seabed without a structure. A tentative explanation is provided for this phenomenon

Gene cluster analysis for the biosynthesis of elgicins, novel lantibiotics produced by <it>paenibacillus elgii </it>B69

<p>Abstract</p> <p>Background</p> <p>The recent increase in bacterial resistance to antibiotics has promoted the exploration of novel antibacterial materials. As a result, many researchers are undertaking work to identify new lantibiotics because of their potent antimicrobial activities. The objective of this study was to provide details of a lantibiotic-like gene cluster in <it>Paenibacillus elgii </it>B69 and to produce the antibacterial substances coded by this gene cluster based on culture screening.</p> <p>Results</p> <p>Analysis of the <it>P. elgii </it>B69 genome sequence revealed the presence of a lantibiotic-like gene cluster composed of five open reading frames (<it>elgT1</it>, <it>elgC</it>, <it>elgT2</it>, <it>elgB</it>, and <it>elgA</it>). Screening of culture extracts for active substances possessing the predicted properties of the encoded product led to the isolation of four novel peptides (elgicins AI, AII, B, and C) with a broad inhibitory spectrum. The molecular weights of these peptides were 4536, 4593, 4706, and 4820 Da, respectively. The N-terminal sequence of elgicin B was Leu-Gly-Asp-Tyr, which corresponded to the partial sequence of the peptide ElgA encoded by <it>elgA</it>. Edman degradation suggested that the product elgicin B is derived from ElgA. By correlating the results of electrospray ionization-mass spectrometry analyses of elgicins AI, AII, and C, these peptides are deduced to have originated from the same precursor, ElgA.</p> <p>Conclusions</p> <p>A novel lantibiotic-like gene cluster was shown to be present in <it>P. elgii </it>B69. Four new lantibiotics with a broad inhibitory spectrum were isolated, and these appear to be promising antibacterial agents.</p

Antiplatelet Aggregation and Antithrombosis Efficiency of Peptides in the Snake Venom of Deinagkistrodon acutus: Isolation, Identification, and Evaluation

Two peptides of Pt-A (Glu-Asn-Trp 429 Da) and Pt-B (Glu-Gln-Trp 443 Da) were isolated from venom liquor of Deinagkistrodon acutus. Their antiplatelet aggregation effects were evaluated with platelet-rich human plasma in vitro; the respective IC50 of Pt-A and Pt-B was 66 μM and 203 μM. Both peptides exhibited protection effects on ADP-induced paralysis in mice. After ADP administration, the paralysis time of different concentration of Pt-A and Pt-B lasted as the following: 80 mg/kg Pt-B (152.8 ± 57.8 s) < 40 mg/kg Pt-A (163.5 ± 59.8 s) < 20 mg/kg Pt-A (253.5 ± 74.5 s) < 4 mg/kg clopidogrel (a positive control, 254.5 ± 41.97 s) < 40 mg/kg Pt-B (400.8 ± 35.9 s) < 10 mg/kg Pt-A (422.8 ± 55.4 s), all of which were statistically shorter than the saline treatment (666 ± 28 s). Pulmonary tissue biopsy confirmed that Pt-A and Pt-B prevented the formation of thrombi in the lung. Unlike ADP injection alone, which caused significant reduction of peripheral platelet count, Pt-A treatment prevented the drop of peripheral platelet counts; interestingly, Pt-B could not, even though the same amount of Pt-B also showed protection effects on ADP-induced paralysis and thrombosis. More importantly, intravenous injection of Pt-A and Pt-B did not significantly increase the hemorrhage risks as clopidogrel

HPLC elution profiles of the pigments extracted from the wild-type and the knockout mutants.

<p>Solid lines, the wild-type and the knockout mutants; dashed lines, the control assays. A, wild-type; B, Δ<i>crtZ</i>; C, Δ<i>crtG</i>; D, Δ<i>crtZG</i>; E, Δ<i>crtY</i>. The major pigments were identified as nostoxanthin (peak 1, λ_max: 274, 450, 476; [M+H]⁺: 601), caloxanthin (peak 2, λ_max: 276, 450, 476; [M+H]⁺: 585), zeaxanthin (peaks 3, 8 and 10, λ_max: 275, 450, 476; [M+H]⁺: 569), 2,2′-dihydroxy-β-carotene (peak 5, λ_max: 272, 450, 476; [M+H]⁺: 569), β-carotene (peaks 4, 6, 7, 9,11 and 12, λ_max:452, 476; [M+H]⁺: 537) and lycopene (peak 13 and 14, λ_max:296, 362, 446, 470, 502; [M+H]⁺: 537).</p