Crystal structure and magnetic behavior of a copper(II)-(pyrazine 2,3-dicarboxylate) coordination polymer: 3D architecture stabilized by H-bonding

Reaction of Cu(ClO₄)₂ · 6H₂O and pyrazine 2,3-dicarboxylate (pzdc) in aqueous ammonia medium results [Cu(pyrazine 2,3-dicarboxylate)(H₂O)₂] · H₂O (1). The X-ray single crystal structure reveals that the compound is a 1D polymeric sinusoidal infinite chain which through intra- and inter-molecular hydrogen bonding interactions, involving lattice and coordinated water molecules with dicarboxylate oxygens and pyrazine nitrogens, gives rise to a 3D architecture. The variable temperature magnetic measurements show weak antiferromagnetic interactions between the Cu(II) centers. The best fit parameters through the typical equation for a uniform copper (II) chain are: J=−0.25 cm⁻¹, g=2.17, R=1.3×10−6. The EPR spectrum does not alter with temperature (from r.t. to 4 K). The spectra are typical for square-pyramidal geometry of copper(II) ions, g_∥=2.24 and g_⊥=2.10 (average g=2.15, in good agreement to the value obtained by susceptibility fit).     

Two μ1,5-dicyanamide bridged 2D and 3D metal complexes formed by covalent bonding and weak interactions

One 2D and one 3D dicyanamide bridged complexes, [Cu(dca)₂(et₂-en)]_n (1) and [Mn(dca)₂(im)₂]_n (2) [dca=dicyanamide, et₂-en=N,N-diethyl-ethylenediamine, im=imidazole], have been synthesized. Both the complexes are 1D by covalent bonding but interchain H-bonding promotes dimensionality. Moreover, π-π interaction among the imidazole ligands also plays an important role to have an interlocked 3D structure for 2. Magnetic study of both the complexes shows weak antiferromagnetic interaction between the metal centers. The magnetic data have been fitted with appropriate equations yielding best fit parameters for 1: J=−0.58±0.02 cm⁻¹, g=2.11±0.01 with R=3.2×10⁻⁶ and for 2, J=−0.21 cm⁻¹, g=2.00 and R=5.6×10⁻⁴.     

“Free” Copper: A New Endogenous Chemical Mediator of Inflammation in Birds

For acceptance of any chemical agent as an endogenous chemical mediator of inflammation, the agent in question must fulfill some biological requirements which are (a) it should be ubiquitously present in tissues in inactive form, (b) it should be activated during process of inflammation whose increase should be identifiable, (c) it should induce or amplify some events of inflammation, (d) there must be some natural inhibitor of such active form in tissues, (e) it should be able to induce inflammatory reaction after exogenous injection, (f) such reaction should be inhibited by exogenous use of their antagonists, and (g) it should be amplified by use of agonists. Copper in its protein free or protein bound form are reported to act as pathogenic factor in inflammatory processes due to oxidative stress. But their role as endogenous chemical mediator of inflammation does not appear to be investigated thoroughly in light of abovementioned biological criterion of mediator. Present study aims at thorough exploration on role of free copper as endogenous chemical mediator of inflammation in light of above facts. It was done by estimation of total copper, protein-bound copper, and free copper along with estimation of free radical generation, increase in vascular permeability, and cellular infiltration during acute inflammatory reaction induced by carrageenan and concanavalin using chicken skin as test model. It was further evaluated by use of exogenous free copper in experimental model and their subsequent inhibition and amplification by chemical chelators of copper. Present study confirms that free copper fulfilled all the biological requirements for accepting it as an endogenous chemical mediator of inflammation.     

Higher expression of SATB2 in hepatocellular carcinoma of African Americans determines more aggressive phenotypes than those of Caucasian Americans

In the United States, Hepatocellular Carcinoma (HCC) incidence has tripled over the past two decades. The disease has disproportionately affected minority and disadvantaged populations. The purpose of this study was to examine the expression of SATB2 gene in HCC cells derived from African Americans (AA) and Caucasian Americans (CA) and assess its oncogenic potential by measuring cell viability, spheroid formation, epithelial‐mesenchymal transition (EMT), stem cell markers and pluripotency maintaining factors in cancer stem cells (CSCs). We compared the expression of SATB2 in human primary hepatocytes, HCC cells derived from AA and CA, and HCC CSCs. Hepatocellular carcinoma cells derived from AA expressed the higher level of SATB2 than those from CA. By comparison, normal human hepatocytes did not express SATB2. Higher expression of SATB2 in HCC cells from AA was associated with greater growth rate, cell viability, colony formation and EMT characteristics than those from CA. Knockout of SATB2 in CSCs by Crispr/Cas9 technique significantly inhibited the expression of SATB2 gene, stem cell markers (CD24, CD44 and CD133), pluripotency maintaining factors (c‐Myc, KLF4, SOX2 and OCT4), and EMT compared with non‐targeting control group. The expression of SATB2 was negatively correlated with miR34a. SATB2 rescued the miR‐34a‐mediated inhibition of CSC's viability. These data suggest that SATB2 is an oncogenic factor, and its higher expression may explain the disparity in HCC outcomes among AA.     

Characterisation of 24-kD proteins from rat testes using polyclonal sera reactive to human sperm antigens

A group of antigens of 24-kD Mr from rat testes were characterised biochemically. These antigens were part of a larger molecule of approximately 200 kD. On treatment with disulfide bond reducing agent, the 200-kD molecule was reduced to subunits. Immunoreactivity was confined to a doublet of approximately 24 kD and a single band of approximately 50 kD Mr after the reduction. Glycoprotein in nature, this antigen shared immunoreactive epitopes with a 40-kD antigen on human spermatozoa. Antiserum raised in rabbits against the 24-kD antigen from rat testes reacted with antigens on the acrosome of human spermatozoa. Agglutination of sperm could be induced by the antiserum. The carbohydrate residue could be removed by mannosidase digestion. Chemical deglycosylation studies showed a slight decrease in molecular weight. Immunoreactivity was however not completely lost after chemical deglycosylation. Isoelectric focusing of the antigen identified nine isoelectric species. Two relatively minor species showed immunoreactivity. Acrosome-reacted spermatozoa showed loss of antigens from acrosome.     

Inhibition of ribosome assembly factor PNO1 by CRISPR/Cas9 technique suppresses lung adenocarcinoma and Notch pathway: Clinical application

Growth is crucially controlled by the functional ribosomes available in cells. To meet the enhanced energy demand, cancer cells re-wire and increase their ribosome biogenesis. The RNA-binding protein PNO1, a ribosome assembly factor, plays an essential role in ribosome biogenesis. The purpose of this study was to examine whether PNO1 can be used as a biomarker for lung adenocarcinoma and also examine the molecular mechanisms by which PNO1 knockdown by CRISPR/Cas9 inhibited growth and epithelial–mesenchymal transition (EMT). The expression of PNO1 was significantly higher in lung adenocarcinoma compared to normal lung tissues. PNO1 expression in lung adenocarcinoma patients increased with stage, nodal metastasis, and smoking. Lung adenocarcinoma tissues from males expressed higher PNO1 than those from females. Furthermore, lung adenocarcinoma tissues with mutant Tp53 expressed higher PNO1 than those with wild-type Tp53, suggesting the influence of Tp53 status on PNO1 expression. PNO1 knockdown inhibited cell viability, colony formation, and EMT, and induced apoptosis. Since dysregulated signalling through the Notch receptors promotes lung adenocarcinoma, we measured the effects of PNO1 inhibition on the Notch pathway. PNO1 knockdown inhibited Notch signalling by suppressing the expression of Notch receptors, their ligands, and downstream targets. PNO1 knockdown also suppressed CCND1, p21, PTGS-2, IL-1α, IL-8, and CXCL-8 genes. Overall, our data suggest that PNO1 can be used as a diagnostic biomarker, and also can be an attractive therapeutic target for the treatment of lung adenocarcinoma.