2‑Nitro-thioglycosides: α- and β‑Selective Generation and Their Potential as β‑Selective Glycosyl Donors

Michael-type addition of thiolates to 2-nitro-d-glucal or to 2-nitro-d-galactal derivatives readily provides 2-deoxy-2-nitro-1-thioglycosides. Kinetic and thermodynamic reaction control permitted formation of either the α- or preferentially the β-anomers, respectively. Addition of achiral and chiral thiourea derivatives to the reaction mixture increased the reaction rate; the outcome is substrate-controlled. The 2-deoxy-2-nitro-1-thioglycosides are excellent glycosyl donors under arylsulfenyl chloride/silver triflate (ArSCl/AgOTf) activation, and they provide, anchimerically assisted by the nitro group, mostly β-glycosides

Regioselective Acylation of Diols and Triols: The Cyanide Effect

Central topics of carbohydrate chemistry embrace structural modifications of carbohydrates and oligosaccharide synthesis. Both require regioselectively protected building blocks that are mainly available via indirect multistep procedures. Hence, direct protection methods targeting a specific hydroxy group are demanded. Dual hydrogen bonding will eventually differentiate between differently positioned hydroxy groups. As cyanide is capable of various kinds of hydrogen bonding and as it is a quite strong sterically nondemanding base, regioselective <i>O</i>-acylations should be possible at low temperatures even at sterically congested positions, thus permitting formation and also isolation of the kinetic product. Indeed, 1,2-<i>cis</i>-diols, having an equatorial and an axial hydroxy group, benzoyl cyanide or acetyl cyanide as an acylating agent, and DMAP as a catalyst yield at −78 °C the thermodynamically unfavorable axial <i>O</i>-acylation product; acyl migration is not observed under these conditions. This phenomenon was substantiated with 3,4-<i>O</i>-unproteced galacto- and fucopyranosides and 2,3-<i>O</i>-unprotected mannopyranosides. Even for 3,4,6-<i>O</i>-unprotected galactopyranosides as triols, axial 4-<i>O</i>-acylation is appreciably faster than <i>O</i>-acylation of the primary 6-hydroxy group. The importance of hydrogen bonding for this unusual regioselectivity could be confirmed by NMR studies and DFT calculations, which indicate favorable hydrogen bonding of cyanide to the most acidic axial hydroxy group supported by hydrogen bonding of the equatorial hydroxy group to the axial oxygen. Thus, the “cyanide effect” is due to dual hydrogen bonding of the axial hydroxy group which enhances the nucleophilicity of the respective oxygen atom, permitting an even faster reaction for diols than for mono-ols. In contrast, fluoride as a counterion favors dual hydrogen bonding to both hydroxy groups leading to equatorial <i>O</i>-acylation

Continuous Production of Graphite Nanosheets by Bubbling Chemical Vapor Deposition Using Molten Copper

We report a bubbling chemical vapor deposition method for mass production of high-quality graphite nanosheets using molten copper as the catalyst for continuous growth. Bubbles containing precursor gas (CH₄ or natural gas) are produced by inserting an aerator into molten copper. High-quality graphite nanosheets with a thickness ranging from a few to 40 graphitic layers are grown on bubble surfaces and carried to the copper surface. The production rate can be as high as 9.4 g/h using a crucible with a volume of 3 L. The high quality of the graphite nanosheets is demonstrated by composites with very high conductivity. The highly conductive composite shows excellent performance in an electromagnetic interference (EMI) shielding application with an EMI effectiveness of >70 dB at X band. Moreover, except for precursor gases, the lack of other chemicals in the growth process makes it an environmentally friendly approach. Natural gas can also be used as the precursor, making it a low-cost production. In addition, the naturally crumpled feature of the graphite nanosheets should allow them to ber used in multiple applications, because restacking can be prevented

Conjugative Transfer of Dioxin–Catabolic Megaplasmids and Bioaugmentation Prospects of a <i>Rhodococcus</i> sp.

Genetic bioaugmentation, in which bacteria harboring conjugative plasmids provide catabolic functions, is a promising strategy to restore dioxin-contaminated environments. Here we examined the conjugative transfer of the dioxin–catabolic plasmids pDF01 and pDF02 harbored by <i>Rhodococcus</i> sp. strain p52. A mating experiment using strain p52 as a donor showed that pDF01 and pDF02 were concomitantly and conjugatively transferred from strain p52 to a <i>Pseudomonas aeruginosa</i> recipient at a conjugation frequency of 3 × 10^–4 colonies per recipient. pDF01 and pDF02 were isolated from the <i>P. aeruginosa</i> transconjugant and identified by Southern hybridization, and they were localized in the transconjugant cells by fluorescence in situ hybridization. Moreover, the catabolic plasmids functioned in the transconjugant, which gained the ability to use dibenzofuran and chlorodibenzofuran for growth, and they were maintained in 50% of the transconjugant cells for 30 generations without selective pressure. Furthermore, conjugative transfer of the catabolic plasmids to activated sludge bacteria was detected. Sequencing of pDF01 and pDF02 revealed the genetic basis for the plasmids’ conjugative transfer and stable maintenance, as well as their cooperation during dioxin catabolism. Therefore, strain p52 harboring pDF01 and pDF02 has potential for genetic bioaugmentation in dioxin-contaminated environments

Diversity-Oriented Enzymatic Modular Assembly of ABO Histo-blood Group Antigens

Enzymatic synthesis of all 15 naturally occurring human ABH antigens was achieved using a diversity-oriented enzymatic modular assembly (EMA) strategy. Three enzyme modules were developed, each one-pot multienzyme module comprises a glycosyltransferase and one or two corresponding sugar nucleotide generating enzyme(s). These multienzyme cascade processes provide an efficient and convenient platform for collective synthesis of all 15 ABH antigens in three operationally simple steps from five readily available disaccharide acceptors and three simple free sugars as donor precursors

HCV replication up-regulates DR4 and DR5.

<p>(A) The mRNA level of DR4, DR5, DcR1, and DcR2 in 9–13 and Huh7 cells was measured using real-time RT-PCR. (B) Huh7 and 9–13 cell lysates were subjected to western blot analyses using a rabbit polyclonal antibody against DR4 or DR5. (C) The DR4 reporter plasmid (DR4/−1156; 100 ng) or DR5 reporter plasmid (DR5/−1192; 100 ng) was co-transfected with the <i>Renilla</i> luciferase reporter plasmid (100 ng) into 9–13 or Huh7 cells cultured in a 24-well plate. After 2 days, the cells were harvested, and the luciferase activity was measured. (A and C) The data from the 9–13 cells were normalized to Huh7 cells to directly show the fold induction caused by HCV. The data are presented with the SD from three independent experiments, and statistical significance was calculated by <i>t</i> test, * indicates a <i>p</i> value less than 0.05.</p

JFH-1 infection up-regulates the expression of DR4 and DR5.

<p>(A) Western blot analysis was performed to measure the expression of DR4 and DR5 in Huh7.5.1 cells infected with JFH-1 1, 2, 3 days post-infection (MOI 0.02). (B) Real-time PCR was performed to measure the mRNA levels of DR4 and DR5 in Huh7.5.1 cells infected with JFH-1 (MOI 0.02) 3 days post-infection. (C) The DR4 reporter plasmid (DR4/−1156; 100 ng) or DR5 reporter plasmid (DR5/−1192; 100 ng) was co-transfected with the <i>Renilla</i> luciferase reporter plasmid (50 ng) into Huh7.5.1 cells, 6 hr later, cells were infected with JFH-1 (MOI 0.5). After 3 days, the cells were harvested, and the luciferase activity was measured. The data from the infected cells were normalized to Huh7.5.1 cells to directly show the fold induction caused by HCV. (D) Huh7.5.1 cells were infected with JFH-1 (MOI 0.5), 3 days later, cells were treated with indicated concentration of TRAIL for 2 hr, and stained with annexin V and PI. The proportion of apoptotic cells was measured using flow cytometry. The data are presented with the SD from three independent experiments, and statistical significance was calculated by <i>t</i> test or two-way ANOVA, * indicates a <i>p</i> value less than 0.05.</p

HCT116 orthotopic transplantation in the nude mice model.

<p>Orthotopic transplantation of control un-transfected HCT116 cells and NIBP knockdown cells in nude mice. Primary tumors weighed less in mice transplanted with NIBP knockdown HCT116 cells compared to mice transplanted with control un-transfected HCT116 cells (967 ± 515 mg <i>vs</i>. 1738 ± 396 mg; <i>p</i> = 0.036).</p

HCV-mediated increased DR4 and DR5 expression is MEK1 dependent.

<p>Huh7 and 9–13 cell lysates (A) or Huh7.5.1 and JFH-1 infected Huh7.5.1 cell (MOI 0.02) lysates (B) were subjected to western blot analyses using antibodies against phospho-MEK1 or MEK1. (C) Untreated 9–13 cells or 9–13 cells treated with 100 µM PD98059, 100 µM SP600125 or DMSO for 2 days were harvested and subjected to western blot analyses using antibodies against DR4 or DR5. (D) The MEK1-specific siRNA or control siRNA (100 pmol) was transfected into 9–13 cells cultured in 6-well plates. 2 days post-transfection, the expression of MEK1, DR4 and DR5 was determined using western blot analyses. (E) Huh7.5.1 cells were transfected with the MEK1-specific siRNA or control siRNA and infected with JFH-1 (MOI 0.02) 6 hr post transfection. 3 days post infection, the expression of MEK1, DR4 and DR5 was determined using western blot analyses. (F) Huh7.5.1 cells were transfected with indicated siRNA, and the expression of MEK1 was measured by using western blot 2 days later. (G) 9–13 cells were transfected with MEK1 siRNA1, MEK1 siRNA2 or scramble RNA, 3 days post transfection, cells were treated indicated concentration of TRAIL for 2 hr, and stained with annexin V and PI. The proportion of apoptotic cells was analyzed by using flow cytometry. (H) Huh7.5.1 cells were transfected with MEK1 siRNA1, MEK1 siRNA2 or scramble RNA, 6 hr later, cells were infected with JFH-1 (MOI 0.5), 3 days post infection, cells were treated indicated concentration of TRAIL for 2 hr, and stained with annexin V and PI. The proportion of apoptotic cells was analyzed by using flow cytometry. The data are presented with the SD from three independent experiments, and statistical significance was calculated by two-way ANOVA, * indicates a <i>p</i> value less than 0.05.</p

CRC patient clinicopathological characteristics and IRS values for NIBP, p-p65, p-ERK1/2, and p-JNK1/2 immunohistochemical expression.

<p>CRC patient clinicopathological characteristics and IRS values for NIBP, p-p65, p-ERK1/2, and p-JNK1/2 immunohistochemical expression.</p