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This work summarizes one-pot synthetic approaches to spiro-fused (di)azoles, which are promising in terms of studying biological activity. Proposed approaches involve condensation reactions of (hetero)cyclic ketones, methylene active moieties, and N-nucleophiles, occurring under mild conditions by both stepwise and concerted mechanisms. The antimicrobial activity of signals from the proposed approaches of cyanosubstituted spiro-membered pyrazolines and pyrrolidines against gram-negative (P. aeruginosa, E. coli) and gram-positive (S. aureus) losses has been studied (EC50 determination (μg/ml)).The well-known component of broad-spectrum antimicrobial drugs, ciprofl oxacin, has been used as a control. It has been found that 3-amino-2-(4-nitrophenyl)-1,2-diazaspiro[4.5]dec-3-ene-4-carbonitrile exhibits the greatest inhibitory eff ect against selected gram-negative bacteria. In this case, the phenyl substituent at the second nitrogen atom of the pyrazoline ring plays an important role, since its replacement with an aroyl fragment reduces the studied eff ect by several tens of times, regardless of the type of the second ring. Substituted spiroindolinopyrrolizidinedicarbonitriles, containing cyano groups at the 2nd carbon atom of the pyrrolizidine ring and a phenyl substituent at the fi rst, also exhibit a moderate and high inhibitory eff ect. For pairs with the same type of substituent position, compounds containing a 3,4 Cl2 substituent in the phenyl fragment have the greatest antimicrobial activity.

The naturally produced, nonprotein amino acid β-N-methylamino-L-alanine (BMAA) has been proposed as a significant contributor to sporadic neurodegenerative disease development worldwide. However, the existing hypothesized mechanisms of toxicity do not adequately explain the role of BMAA in neurodegenerative disease development. There is evidence for BMAA-induced enzyme inhibition, but the effect of BMAA on human stress response enzymes has received little attention, despite the well-described role of oxidative stress in neurodegenerative disease development. The aim of this study was therefore to investigate the effect of BMAA on human catalase activity and compare it to the known inhibitor 3-amino-1,2,4-triazole. BMAA inhibited human erythrocyte catalase in a cell-free exposure to the same extent as the known inhibitor. Based on enzyme kinetics, the inhibition appears to be noncompetitive, possibly as a result of BMAA binding in the nicotinamide adenine dinucleotide phosphate (NADPH) binding site. BMAA-induced catalase inhibition was also observed in a human cell line culture. We therefore propose that BMAA-induced enzyme inhibition, specifically catalase inhibition, is a mechanism of toxicity that may contribute to the neurotoxicity of BMAA, further supporting the role of BMAA in neurodegenerative disease development. [ABSTRACT FROM AUTHOR]

The Michael addition of dehydroalanine-activated ester in situ generated from N,N-phthaloyl-serine with o-phenylenediamine followed by cyclization has been established under mild conditions, which afforded 3-phthalimido-1,5-benzodiazepine-2-one derivatives in moderate to good yields. [ABSTRACT FROM AUTHOR]

A new energetic salt, 3-amino-1,2,4-triazole dinitramide (ATADN), was synthesized through the combination of 3-amino-1,2,4-triazole cation and oxygen-rich dinitramide anion. The structure of ATADN was confirmed by single-crystal X-ray diffraction, elemental analysis, Fourier transform infrared spectroscopy, ultraviolet-visible spectrometry, and nuclear magnetic resonance spectroscopy. The thermal stability of ATADN was studied using differential scanning calorimetry, thermogravimetric analysis (TG), and TG tandem infrared spectrum. The thermal decomposition kinetics parameter was also calculated using the differential thermal analysis data based on Kissinger's method. Results indicated that ATADN exhibited resistance to thermal decompositions of up to 439 K, and a corresponding activation energy of Ea = 281.9 kJ·mol-1.Moreover, itsmechanical sensitivity and detonation properties were evaluated, which showed promising results for its potential application as a highly explosive compound. [ABSTRACT FROM AUTHOR]

Considerable attention has been paid to utilizing molybdenum (Mo) as a new generation of barrier layer material in the integrated circuit industry. However, there have a small amount of papers for Mo chemical mechanical polishing (CMP). In this study, the inhibition effect of 3-amino-1, 2, 4-triazole (ATA) on corrosion and CMP of Mo in the weakly alkaline slurry was investigated. Electrochemical experiment and chemical mechanical polishing experiment demonstrated that 100 ppm ATA has an excellent inhibition performance of Mo (removal rate of Mo decreased from 509 Å/min to 322 Å/min, static etching rate of Mo decreased from 839 Å/min to 208 Å/min and Mo surface roughness decreased from 9.48 nm to 1.01 nm). Langmuir adsorption isotherm analysis found that physical and chemical adsorption exists simultaneously between ATA and Mo. X-ray photoelectron spectroscopy analysis showed that the addition of ATA changed the contents of different kinds of Mo oxides. With the decreasing of MoO 3 , more MoO 2 was generated and protected Mo from corrosion. This paper is devoted to studying the inhibition effect of a traditional corrosion inhibitor on a new barrier layer material and analyzing its mechanism. Additionally, this paper is also helpful to prevent galvanic corrosion between Mo and other interconnection materials during CMP. • The addition of 100 ppm ATA decreases the removal rate, static etching rate and surface quality roughness of Mo. • ATA can chemically and physically adsorb on Mo surface and form a passivation film. • The addition of ATA can increase the content of MoO 2 on Mo surface to protect it from corrosion. [ABSTRACT FROM AUTHOR]

Benzazolo [2,1-b]quinazolinones and triazolo[2,1-b]quinazolinones were synthesized in high yields by the condensation reaction of an aldehyde and a cyclic β-diketone with 2 - aminobenzimidazole, 2 - aminobenzothiazole or 1, 2, 4 - triazole derivatives in 1 - butyl - 3 -methylimidazolium bromide as an ionic liquid under classic heating conditions within 5-60 minutes.

Cu-catalyzed A3 (amine, aldehyde, and alkyne) coupling reactions were investigated for the synthesis of 3-amino-1,4-diynes. Although metal-catalyzed A3-coupling reactions have been extensively used to synthesize various propargylamines, the A3-coupling for the synthesis of 3-amino-1,4-diynes has been rarely reported. In this study, various symmetrical 3-amino-1,4-diynes were synthesized by the sequential Cu-catalyzed dealkynylation of propargyl aldehydes followed by A3-coupling. Unsymmetrical 3-amino-1,4-diynes were also synthesized in 49-85 % yields by Cu-catalyzed A3-coupling. [ABSTRACT FROM AUTHOR]

Two new complexes, [Cu(Hatz)(pdcam)(H2O)]. (H2O) (1) and [Cu(Hatz))(pdc)H2O]·(H2O) (2) (Hatz = 3-amino-1,2,4-triazolate, H2pdcam = 2,6-pyridine-dicarboxamide, H2pdc = 2,6-pyridine-dicarboxylato), were synthesized under hydrothermal conditions and were characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffraction. Both crystallize in monoclinic system, space group P2(1)/c with a = 12.9218(13), b = 6.3094(7), c = 16.4110(16) Å, β = 97.862(2)°, and Z = 4 for 1 and space group P 2(1)/c with a = 9.4290(9), b = 18.2847(18), c = 7.2576(7) Å, β = 101.6180(10)°, and Z = 4 for 2. X-ray analysis demonstrates that complexes 1 and 2 are discrete mononuclear species. The both Cu(II) atoms exhibit a tetragonal pyramid coordination, type 4 + 1. In two complexes, the coordination entities are further organized via hydrogen-bonding interactions to generate multifarious supramolecular networks. Thermal stabilities of two complexes were examined by thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Three 3-amino-1,2,4-triazole (Hatz)-based paramagnetic metal complexes, {[Co2(Hatz)2(nip)2]·H2O}n(1), [Co(atz)(nb)]n(2), and {[Co3(H2O)4(Hatz)6(btc)2]·11.5H2O} (3) (nip2−= 5-nitroisophathalate, nb–=p-nitrobenzolate, and btc3–= 1,2,4-benzenetricarboxylate), were respectively prepared by introducing differently carboxylate-containing rigid coligands. All these complexes were structurally and magnetically characterized by single-crystal and powder X-ray diffractions, elemental analysis, FT-IR spectra, thermogravimetric and magnetic measurements. Complex1has a four-connected CdSO4-type framework with binuclear subunits periodically extended by ditopicμ-N1, N3-Hatz and carboxylate-containing linkers. Tetrahedral CoIIions in2are periodically interlinked into an undulated layer by anionicμ3-N1,N2,N3-atz−connectors with deprotonated nb–spacers located on the both sides. By contrast, complex3is a centrosymmetric trinuclear molecule aggregated by six neutralμ-N1, N3-Hatz molecules. The structural difference of1–3is significantly due to the flexible binding modes adopted by triazolyl and carboxylate groups. Additionally,1exhibits a field-induced metamagnetic transition from an antiferromagnetic ordering to a weak ferromagnetic state resulting from the magnetic competition between triazolyl and carboxylate mediators. Instead, comparable antiferromagnetic couplings transmitted by cyclic triazolyl groups are observed in the nearest neighbors of2and3. [ABSTRACT FROM PUBLISHER]

Three 3-amino-1, 2, 4-triazole (atz)-based paramagnetic complexes, [Mn(atz)(pa)] n ( 1), {[Mn(atz)1.5(hip)] ·H2O} n ( 2), and [Mn(H2O)2(atz)2(nb)2] ( 3) (H2pa = o-phthalic acid, H2hip = 5-hydroxylisophthalic acid, and Hnb = p-nitrobenzoic acid) were prepared by introducing different carboxylate-containing aromatic coligands, and structurally and magnetically characterized. Helical MnII-atz and bent MnII-pa2- chains are crosslinked by sharing the same metal sites to generate a honeycomb-shaped framework of 1. The undulated MnII-atz layers constructed from 22-member metallomacrocycles are periodically supported by ditopic hip2- ligands to lead to a pillared-layer structure of 2. In contrast, complex 3 is a centrosymmetric mononuclear entity, which is assembled into a three-dimensional supramolecular network by abundant hydrogen-bonding interactions. The structural difference of 1- 3 is significantly due to the combinations of the flexible coordination modes adopted by the mixed atz and carboxylate groups. Weak and comparable antiferromagnetic couplings are observed in the nearest neighbors of 1- 3, which are cooperatively transmitted either by short carboxylate and/or atz heterobridges or by weak non-covalent interactions. [ABSTRACT FROM AUTHOR]

In this report a major sweet potato catalase was detected and identified from fully-expanded mature leaves using an in-gel activity staining assay with native- and SDS-PAGEs. The catalase activity was optimal from pH 8 to 12, and was repressed by β-mercaptoethanol and a catalase inhibitor 3-amino-1,2,4- triazole. However, catalase activity was much less affected by temperature within the range of 5 to 45°C. Temporal and spatial expression demonstrated that it was specifically detected in leaves, but not in roots and stems. Its activity increased from the immature L2 leaves, reached the maximum in the fully-expanded mature L3 leaves, slightly decreased in the partly-yellowing senescent L4 leaves, and was almost undetectable in the completely yellow L5 leaves, which were similar to the folded and unopened immature L1 leaves. The catalase levels approximately inversely correlated with the H2O2 amounts in leaves of different developmental stages. Dark and ethephon, an ethylene-releasing compound, also enhanced catalase activities from 6 h to 24 h, however, the enhanced activity decreased from 24 h to 48 h in detached leaves after treatment. The catalase levels also approximately inversely correlated with the H2O2 amounts in treated leaves. These data suggest a possible role for sweet potato catalase in coping with H2O2 scavenging in leaves. Based on these data we conclude that a major leaf-type catalase is identified in sweet potato leaves. Its activity level is maximal in mature leaves and becomes significantly lower in natural and in induced senescent leaves. The leaf-type sweet potato catalase likely functions in H2O2 removal in leaves. [ABSTRACT FROM AUTHOR]

We performed a uterotrophic assay, the Hershberger assay, and the 28-day repeated-dose toxicity study (enhanced OECD test guideline no. 407) of 3-amino-1,2,4-triazole based on the OECD draft protocols. In the uterotrophic assay, female SD rats were subcutaneously injected with the chemical at doses of 0, 100, 300, and 1,000 mg/kg on each of 3 days from postnatal day 20 to day 22, and no changes were observed. In the Hershberger assay, the test chemical was orally administered at doses of 0, 40, 200, and 1,000 mg/kg/day to castrated male Wistar rats for 10 consecutive days beginning on postnatal day 56, and no androgen agonistic and antagonistic changes were observed. Alternatively, when the test chemical was orally administered at doses 0, 5, 25, and 125 mg/kg/day for at least 28 days in the subacute oral toxicity study, thyroid follicular epithelial cell hypertrophy with increased thyroid weights was detected in the male and female rats in 25 and/or 125 mg/kg groups, and hypertrophy of the anterior pituitary cells with increased pituitary weights in male and female rats was also observed in the 125 mg/kg group. Furthermore, serum T3 and T4 values decreased and serum TSH values increased in male and female rats in the 125 mg/kg group. Therefore, 3-amino-1,2,4-triazole was concluded to have anti-thyroid acting as endocrine-mediated effects, but no estrogenic or androgenic effects. In addition, decreased body weight, and abnormal biochemical parameters attributed to thyroid, liver or kidney dysfunction were observed in male and female rats in the 25 and/or 125 mg/kg groups. [ABSTRACT FROM AUTHOR]

Abstract: Telomere shortening and redox imbalance have been related to the aging process. We used cultured mouse embryonic fibroblasts (MEF) isolated from mice lacking telomerase activity (Terc−/−) to analyze the redox balance and the functional consequences promoted by telomerase deficiency. Comparison with wild-type (WT) MEF showed that Terc−/− MEF had greater oxidant damage, showing higher superoxide anion and hydrogen peroxide production and lower catalase activity. Restoration of telomerase activity in Terc−/− MEF increased catalase expression and activity. TGF-β1 and collagen type IV levels were higher in Terc−/− than in WT MEF. TGF-β1 promoter activity decreased when Terc−/− MEF were incubated with exogenous catalase, suggesting that catalase deficiency is the cause of the TGF-β1 increase. Similar results were obtained in vivo. Homogenized renal cortex from 6-month-old Terc−/− showed higher oxidant capacity, lower catalase activity, greater oxidative damage, and higher TGF-β1 and fibronectin levels than that from WT mice. In summary, telomerase deficiency reduces catalase activity, determining a redox imbalance that promotes overexpression of TGF-β1 and extracellular matrix proteins. [Copyright &y& Elsevier]

Abstract: A novel three-dimensional organic–inorganic hybrid solid [Zn3(3atrz)2(H2O)2(MoO4)2] n (1) (3atrz=3-amino-1,2,4-triazole) constructed from two-dimensional Mo–O–Zn bimetallic oxide networks was prepared under hydrothermal condition and characterized. Unprecedented {Zn6Mo6} 12 metal central-membered inorganic rings together with novel {Zn6(3atrz)6} metal–organic coordination rings exist in this structure. [Copyright &y& Elsevier]

Abstract: Peroxisomes generate hydrogen peroxide, a reactive oxygen species, as part of their normal metabolism. A number of pathological situations exist in which the organelle''s capacity to degrade the potentially toxic oxidant is compromised. It is the peroxidase, catalase, which largely determines the functional antioxidant capacity of the organelle, and it is this enzyme that is affected in aging, in certain diseases, and in response to exposure to specific chemical agents. To more tightly control the enzymatic activity of peroxisomal catalase and carefully document the effects of its impaired action on human cells, we employed the inhibitor 3-amino-1,2,4-triazole. We show that by chronically reducing catalase activity to approximately 38% of normal, cells respond in a dramatic manner, displaying a cascade of accelerated aging reactions. Hydrogen peroxide and related reactive oxygen species are produced, protein and DNA are oxidatively damaged, import into peroxisomes and organelle biogenesis is corrupted, and matrix metalloproteinases are hyper-secreted from cells. In addition, mitochondria are functionally impaired, losing their ability to maintain a membrane potential and synthesize reactive oxygen species themselves. These latter results suggest an important redox-regulated connection between the two organelle systems, a topic of considerable interest for future study. [Copyright &y& Elsevier]

Abstract: Glutathione (GSH), as the major small-molecule antioxidant in cells, has been implicated in the regulation of cell proliferation and apoptosis. Salvicine (SAL), a novel diterpenoid quinone compound, exhibits potent antitumor activities both in vitro and in vivo by poisoning topoisomerase II (Topo II) and has entered Phase II clinical trials for cancer therapy. Herein, we provide further evidence that SAL-induced DNA double-strand breaks (DSBs) and apoptosis by GSH depletion drives H2O2 generation and Topo II inhibition. Our data reveal that treatment with SAL results in a pronounced increase in intracellular H2O2 and is accompanied by the occurrence of DNA DSBs and apoptosis in epithelial HeLa cells. Furthermore, SAL was also noted to trigger a dramatic depletion of intracellular GSH via its direct reaction with GSH. Importantly, the introduction of GSH and overexpression of catalase antagonized SAL-mediated DNA DSBs and apoptosis, and the GSH synthesis inhibitor dl-buthionine-[S,R]-sulfoximine reduced SAL-mediated H2O2 generation, indicating that SAL-mediated H2O2 generation is derived from intracellular GSH depletion. Notably, SAL-mediated Topo II inhibition was also concentration-dependently reversed by GSH. Furthermore, we found that Topo II-defective HL-60/MX2 cells were almost completely resistant to SAL-induced DNA DSBs, suggesting that, in addition to its direct inhibitory effect on Topo II, SAL-mediated H2O2 generation may also trigger DNA DSBs via poisoning of Topo II. All these findings together suggest that GSH-depletion-driven H2O2 generation and Topo II inhibition are both critical for SAL-induced DNA DSBs and apoptosis. [Copyright &y& Elsevier]

Abstract: Rat astrocytes accumulate extensive DNA single-strand breakage in response to agents promoting activation of NADPH oxidase. Proinflammatory stimuli, as bacterial lipopolysaccharide associated with interferon-γ, caused a rapid/robust burst of superoxide radicals, sensitive to NADPH oxidase inhibition, followed by dismutation to H2O2, the species resulting in DNA damage via a Fenton-type reaction. There was no contribution of superoxide radical/H2O2 of mitochondrial origin and there was no evidence for the formation/involvement of peroxynitrite. On the other hand, astrocytes were virtually invulnerable to the DNA-damaging effects of exogenous peroxynitrite, an agent causing DNA strand scission in other cell types, via the Ca2+-dependent mitochondrial formation of superoxide radical/H2O2. Resistance was not dependent on scavenging of peroxynitrite but, rather, on insufficient mitochondrial Ca2+ accumulation. Hence, different manipulations resulting in an increase of the mitochondrial Ca2+ pool were invariably associated with the formation of DNA-damaging levels of H2O2. In conclusion, it appears that the strategy adopted by astrocytes to avoid inflammation-dependent genotoxic events, in particular those mediated by peroxynitrite, is to prevent mitochondrial Ca2+ accumulation, critical for the formation of secondary species largely responsible for DNA damage induced by peroxynitrite. [Copyright &y& Elsevier]

Abstract: Cadmium (Cd) is a known industrial and environmental pollutant. In the present work, an in vivo spin-trapping technique was used in conjunction with electron spin resonance (ESR) spectroscopy to investigate free radical generation in rats following administration of cadmium chloride (CdCl2, 40 μmol/kg) and the spin trapping agent α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN, 1 g/kg). In Cd-treated rats, POBN radical adducts were formed in the liver, were excreted into the bile, and exhibited an ESR spectrum consistent with a carbon-centered radical species probably derived from endogenous lipids. Isotope substitution of dimethyl sulfoxide [(CH3)2SO] with 13C demonstrated methyl radical formation (POBN/ 13CH3). This adduct indicated the production of hydroxyl radical, which reacted with [(13CH3)2SO] to form 13CH3, which then reacted with POBN to form POBN/ 13CH3. Depletion of hepatic glutathione by diethyl maleate significantly increased free radical production, whereas inactivation of Kupffer cells by gadolinium chloride and chelation of iron by desferal inhibited it. Treatment with the xanthine oxidase inhibitor allopurinol, the catalase inhibitor aminobenzotriazole, or the cytochrome P450 inhibitor 3-amino-1,2,4-triazole had no effect. This is the first study to show Cd generation of reactive oxygen- and carbon-centered radical species by involvement of both iron mediation through iron-catalyzed reactions and activation of Kupffer cells, the resident liver macrophages. [Copyright &y& Elsevier]

Abstract: dlk1 is an epidermal growth factor (EGF)-like homeotic protein containing an intracellular region, a single transmembrane domain, and an extracellular region possessing six EGF-like repeats and a protease-target sequence. dlk1 functions as a modulator of adipogenesis, and other differentiation processes. The molecular mechanisms by which dlk1 regulates these processes are unclear. It has been reported that different Dlk1 mRNA spliced variants, encoding for isoforms possessing the protease-target sequence or not, determine the production of membrane-associated or soluble, secreted extracellular dlk1 proteins that appear to affect adipogenesis of 3T3-L1 cells differently. In particular, only soluble variants inhibit this process. Some recent evidence suggest that dlk1 may modulate extracellular stimuli inducing differentiation. Thus, an enforced decrease of Dlk1 expression in BALB/c 3T3 cells, which results in an increase of their adipogenic potential in response to insulin-like growth factor 1 (IGF-1), modifies the kinetics and levels of activation of ERK1/2 triggered by it. In this work, we identified a strong and specific interaction between the protease-target dlk1 region and the non-IGF binding region of IGF binding protein 1 (IGFBP1), a protein that binds to IGFs and modulates their action. We also observed that the increased adipogenic potential of 3T3-L1 cells caused by diminishing Dlk1 expression through transfection with an antisense Dlk1 expression construct was inhibited by the presence of IGFBP1 in the differentiation medium. On the other hand, the presence of IGFBP1 in the culture medium slightly increased the adipogenic potential of control 3T3-L1 cells, expressing regular levels of Dlk1. These data suggest that membrane dlk1 variants bind to extracellular IGFBP1/IGF-1 complexes, which may favor the release of IGF-1 and increase the local concentration of free IGF-1 that can enhance IGF receptor signaling, leading to adipogenesis. [Copyright &y& Elsevier]

Abstract: The mutagenicities of various carcinogens induced by liver microsomes are increased in the presence of liver cytosol in rodents. It still remains, however, to be clarified which factor or factors in the cytosol enhance(s) the microsome-mediated mutagenicities. In the present study, we sought to identify the enhancing factor in liver cytosol prepared from rats using the microsome-mediated Salmonella mutagenicity induced by 2-amino-6-methyldipyrido [1,2-a:3′,2′-d] imidazole (Glu-P-1). By a series of chromatographic steps, we purified a 16-kDa protein on SDS-PAGE from the cytosol of rat livers. Partial amino acid sequences of this protein revealed that the 16-kDa protein was copper, zinc-superoxide dismutase (CuZn-SOD). The purified CuZn-SOD enhanced the microsome-mediated mutagenicities of several heterocyclic amines and aromatic amines. Furthermore, bovine and human CuZn-SOD also enhanced the microsome-mediated mutagenicity of Glu-P-1. The CuZn-SOD caused an increase in the mutagenicity of N-hydroxylated Glu-P-1 formed from Glu-P-1 by the microsomes, although CuZn-SOD did not affect either the formation or the stability of the N-hydroxylated derivative. These findings suggest that the enhancing cytosol factor for the mutagenicity of Glu-P-1 is CuZn-SOD, which stimulates the mutagenicity of N-hydroxylated Glu-P-1 without changing its metabolism. [Copyright &y& Elsevier]

Abstract: Insulin-like growth factors (IGFs) belong to a family of growth factors with structural homology to proinsulin. Up till now, no specific details regarding the transcriptional regulation by autocrine, paracrine or endocrine effector molecules in vivo have been described for the IGF-II gene. This is in big contrast to IGF-I gene transcription which has been studied more extensively. To better understand how the IGF-II gene is controlled at the gene transcription level, we have isolated the common carp IGF-II gene together with the 5′-flanking region by genomic library screening. The mature IGF-II protein was encoded by exon 2 and exon 3. Transient transfection of the 5′-flanking region containing a TATA box-like sequence into cultured eukaryotic cells revealed that it is a strong promoter with definitive tissue specificity. Nucleotides between −301 and −62 in the promoter are essential to drive the basal IGF-II gene expression; whereas nucleotides between −891 and −416 in the promoter are responsible for the growth hormone activation. Using electrophoretic mobility shift assay and yeast one-hybrid screening, it was demonstrated that α1-antitrypsin could bind specifically to the nucleotide position −301 to −262 of the gene promoter. Co-transfection studies revealed that the over-expression of α1-antitrypsin increased the IGF-II promoter activity by 3.4-fold, further confirming that α1-antitrypsin acts as a trans-acting factor on the IGF-II promoter. [Copyright &y& Elsevier]

Abstract: Catalase (CAT; EC 1.11.1.6) isolated from leaves of the halophytic plant Mesembryanthemum crystallinum is characterized by a high apparent molecular mass of about 320kDa, and high resistance to denaturing agents (10% ME). SDS-treatment breaks active oligomeric CAT into the less active and putatively dimeric form of 160kDa apparent molecular mass. Three subunits are resolved after denaturing PAGE: 79, 74 and 62kDa. Higher molecular masses of subunits coincide with increased activity of CAT. M. crystallinum leaf CAT reveals a diel variation in the resistance to denaturing factors and the stability of CAT is increased in a light-dependent manner both in C3- and in CAM-induced plants. Unchanged level of leaf CAT transcripts is documented in the diurnal cycle of C3 plants and after salinity-induced crassulacean acid metabolism (CAM). [Copyright &y& Elsevier]

The inhibitor of catalase 3-amino-1,2,4-triazole (AMT) was used to study the physiological role of catalase in the yeast Saccharomyces cerevisiae under starvation. It was shown that AMT at the concentration of 10 mM did not affect the growth of the yeast. In vivo and in vitro the degree of catalase inhibition by AMT was concentration- and time-dependent. Peroxisomal catalase in bakers’ yeast was more sensitive to AMT than the cytosolic one. In vivo inhibition of catalase by AMT in S. cerevisiae caused a simultaneous decrease in glucose-6-phosphate dehydrogenase activity and an increase in glutathione reductase activity. At the same time, the level of protein carbonyls, a marker of oxidative modification, was not affected. Possible mechanisms compensating the negative effects caused by AMT inhibition of catalase are discussed. [ABSTRACT FROM AUTHOR]

A series of new complexes with mixed ligands of the type [ML(C3H3O2)2]· nH2O (( (1) M=Mn, n=1; (2) M=Co(II), n=2; (3) M=Ni(II), n=4; (4) M=Cu(II), n=1.5; (5) M=Zn(II), n=0; L=3-amino-1,2,4-triazole and (C3H3O2)=acrylate anion) were synthesized and characterised by chemical analysis and IR data. In all complexes the 3-amino-1,2,4-triazole acts as bridge while the acrylate acts as bidentate ligand except for complex (5) where it is found as unidentate. The thermal behaviour steps were investigated in nitrogen flow. The thermal transformations are complex processes according to TG and DTG curves including dehydration, acrylate ion and 3-amino-1,2,4-triazole degradation respectively. The final products of decomposition are the most stable metal oxides, except for complex (4) that leads to metallic copper. [ABSTRACT FROM AUTHOR]

Abstract: Heterocyclic amines (HCAs), such as Trp-P-1, PhIP, and IQ, are notorious food-born carcinogens. This study examined the inhibitory effects of HCAs on the expression of interleukin-8 (IL-8), which is an important chemokine for the initiation of innate immune responses that function by recruiting immune cells to inflamed sites. Among HCA types tested, only Trp-P-1 showed a robust inhibition of the lipopolysaccharide (LPS)-induced IL-8 expression at both mRNA and protein levels in a human monocytic cell-line, THP-1. However, Trp-P-1 did not inhibit the DNA-binding abilities of the transcription factors NF-κB, AP-1, and NF-IL6, all of which are known to regulate IL-8 transcription. Meanwhile, treatment with actinomycin D facilitated the Trp-P-1-induced down-regulation of IL-8 expression in LPS-stimulated THP-1 cells, implying that the inhibition might be due to a decrease in the stability of IL-8 mRNA rather than an attenuation of IL-8 transcription. Furthermore, Trp-P-1 also inhibited phosphorylation of p38 MAP kinase, which is involved in the regulation of IL-8 mRNA stability. Exogenous addition of ionomycin rescued both the IL-8 protein levels and phosphorylation of p38 MAP kinase inhibited by Trp-P-1. Collectively, these results suggest that Trp-P-1 suppresses LPS-induced IL-8 production in human monocytic cells through down-regulation of an intracellular calcium/p38 MAP kinase-dependent pathway, leading to the reduction of IL-8 mRNA stability. [Copyright &y& Elsevier]

Abstract: SF3b155 and p14 are essential components of spliceosome core that recognize the branch point adenosine, a critical step in splicing in eukaryotes. Trypanosomes are unusual since every transcribed gene is processed by trans-splicing instead of cis-splicing. Thus, the trans-spliceosome emerges as an interesting anti-parasitic drug target since this process is not present in mammalian hosts. Here, we present the orthologues of these proteins in Trypanosoma cruzi that interact strongly with each other. To define similarities and differences with the human pair, we performed a detailed alanine scan analysis that allowed us to identify the regions and the critical amino acids of T. cruzi SF3b155 involved in interaction with p14. We demonstrate that the T. cruzi SF3b155 interface is larger and contains more complex elements than its human counterpart. Additionally, our results provide the first insights into the core of the putative mRNA processing complex of trypanosomes. [Copyright &y& Elsevier]

Abstract: The bacterial metabolite kinamycin F, which is being investigated as a potent antitumor agent, contains an unusual and potentially reactive diazo group, a paraquinone, and a phenol functional group. Kinamycin F reacted with glutathione (GSH) in a complex series of reactions which suggested that kinamycin F may have its cytotoxicity modulated by GSH. Consistent with this idea, 2-oxo-4-thiazolidinecarboxylic acid treatment to increase cellular GSH levels and buthionine sulfoximine treatment to decrease GSH levels resulted in decreased and increased kinamycin F cytotoxicity, respectively, in K562 leukemia cells. Kinamycin F weakly bound to DNA and induced DNA damage in K562 cells that was independent of GSH levels. The GSH-promoted DNA nicking induced by kinamycin F in vitro was attenuated by deferoxamine, dimethyl sulfoxide, and catalase, which indicated that DNA damage initiated by this agent occurred in an iron-, hydrogen-peroxide-, and hydroxyl-radical-dependent manner. Electron paramagnetic resonance spectroscopy experiments showed that the GSH/kinamycin F system produced a semiquinone free radical and that the hydrogen peroxide/peroxidase/kinamycin F system generated a phenoxyl free radical. In conclusion, the results indicated that kinamycin F cytotoxicity may be due to reductive and/or peroxidative activation to produce DNA-and protein-damaging species. [Copyright &y& Elsevier]

Abstract: Rhodopsin kinase (RK) is a conserved component of the light adaptation and recovery pathways shared among rod and cone photoreceptors of a variety of species. To gain insight into transcriptional mechanisms driving RK and potentially other genes of similar spatial profile, the components and the interactions of the highly compact enhancer/promoter region (E/P) upstream of the human RK gene were examined. Cross-species comparison outlined an active 49-bp widely shared E/P core as the major site of conservation in the entire 5′ flanking sequence. The area consisted of a bicoid-type homeodomain recognition cassette and a unique T-rich module interacting with TATA-binding proteins. Homeodomain interactions involved primarily Crx and secondarily Otx2. Both strongly stimulated the E/P. In the absence of Crx, persistent E/P activity shifted from the outer retina to the inner to follow the Otx2 pattern. The spatial patterns were largely unaffected by the absence of rod transcription factors, Nrl and Nr2e3, and the RK transcriptional activity preceded the surge in rod-specific transcription. Conserved bicoid homeodomain factors thus appear to be the key factors governing localization of RK E/P activity in retina and photoreceptors. [Copyright &y& Elsevier]

Abstract: We have cloned, expressed, isolated and characterized a hexameric tyrosine-coordinated heme protein (HTHP) from the marine bacterium Silicibacter pomeroyi. HTHP shows peroxidase and catalase activity and has a high thermal stability. As-isolated HTHP has absorption maxima at 407, 495, 504, 532 and 622 nm wavelength. Upon reduction maxima at 430, 564 and 596 nm wavelength are discernible. The crystal structure of HTHP reveals a hexameric, ring-like arrangement of six monomers. Each monomer binds a solvent accessible heme group, which is stabilized by the interaction of three neighboring monomers. The pocket around the heme distal side is positively charged due to three conserved arginine residues in direct vicinity. The heme iron is penta-coordinated with a tyrosine residue as proximal ligand. The coordinating hydroxyl-group of the tyrosine ligand interacts with the guanidinium group of a nearby arginine residue, an arrangement closely resembling the catalytic dyad found in monofunctional heme-containing catalases and coral allene oxide synthases, which are b-type cytochromes with tyrosine coordination trans to an empty coordination site. Despite the similarity in heme coordination HTHP is functionally and structurally unrelated to catalases and other heme-containing proteins. Its hexameric arrangement, solvent accessible heme binding pocket and heme coordination by tyrosine render HTHP a unique protein with unusual properties. A database search against complete and incomplete genomes shows that the 76 amino acid residues sequence of HTHP is unrelated to characterized proteins, but is homologous to orfs found in a phylogenetically diverse set of bacteria with sequence identities of 30–76%. We therefore propose that HTHP is the prototype of a new class of heme proteins. [Copyright &y& Elsevier]

Abstract: This article reviews the synthesis of ruthenium phthalocyanine and naphthalocyanine complexes highlighting important advances, and examines their physical properties and applications. [Copyright &y& Elsevier]

Abstract: The release of zinc (Zn) from glutamatergic synapses contributes to the neuropathology of ischemia, traumatic brain injury, and stroke. Astrocytes surround glutamatergic synapses and are vulnerable to the toxicity of Zn, which impairs their antioxidative glutathione (GSH) system and elevates the production of reactive oxygen species (ROS). It is not known whether one or both of these actions are the primary cause of Zn-induced cell death in astrocytes. Using primary rat astrocyte cultures we have examined whether Zn-mediated impairment of GSH redox cycling is the main source of its toxicity. Zn acetate at concentrations of 100 μM or greater were found to inactivate glutathione reductase (GR) via an NADPH-dependent mechanism, while concentrations of 150 μM and above caused substantial cell death. Furthermore, Zn increased the ratio of GSSG:GSH in astrocytes, increased their export of GSSG, slowed their clearance of exogenous H2O2, and promoted the intracellular production of ROS. In contrast, the GR inhibitor, carmustine, did not induce cell death, cause the production of ROS, or alter the GSH thiol redox balance. Taken together these results indicate that Zn toxicity in astrocytes is primarily associated with the generation of intracellular ROS, rather than the inhibition of GR. [Copyright &y& Elsevier]

Background & Aims: There is convincing evidence from animal and human studies that infection with parasitic helminths can alleviate the histopathology and symptoms of colitis. Here the ability of the rat tapeworm Hymenolepis diminuta to affect the course of oxazolone-induced colitis (a TH2 model) was assessed. Methods: Mice were infected with H diminuta and 8 days later they received oxazolone (3 mg in 50% EtOH, intrarectal). On autopsy (3 or 7 days postoxazolone), disease severity was assessed by macroscopic clinical scores, histologic damage scores, myeloperoxidase and eosinophil peroxidase activity, and cytokine synthesis. Results: As gauged by all markers of gut function, infection with H diminuta caused a significant exacerbation of oxazolone-induced colitis. Indeed, while mice receiving oxazolone only began to recover ∼3–4 days posttreatment, the cotreated group continued to deteriorate. Helminth infection, independent of oxazolone administration, enhanced IL-4, IL-5, IL-10, and IL-13 production from in vitro stimulated immune cells and evoked increases in colonic eosinophil peroxidase of cotreated mice. Finally, while knockout of natural killer (NK) and NK-T cells by administration of a neutralizing NK1.1 antibody reduced the inflammation in oxazolone and oxazolone + H diminuta-treated animals, mice in the latter group still displayed significant colitis. Conclusions: We have shown that H diminuta infection is beneficial in other models of colitis. The current data is presented as a caveat to the position that parasitic helminths in general can be considered as a therapy for heterogeneous inflammatory disorders without careful analysis of the immunologic basis of the condition. [Copyright &y& Elsevier]

Abstract: Corrosion of copper in aerated acidic chloride pickling (0.5 M HCl) solutions and its inhibition by 3-amino-1,2,4-triazole-5-thiol (ATT) have been investigated using electrochemical techniques and weight-loss measurements, along with Raman spectroscopy. Electrochemical measurements for copper after varied immersion periods of 0, 24, and 48 h showed that the presence of ATT and the increase of its concentration significantly decrease cathodic, anodic, corrosion () currents and corrosion rates (), as well as the dissolution currents at 300 mV vs Ag/AgCl, while increasing polarization resistance (), degree of surface coverage (θ) and inhibition efficiency (IE%) to a great extent. Weight-loss measurements after different immersion periods of 6 to 48 h revealed that the dissolution of copper decreased to a minimum and the corresponding IE% increased with increasing ATT concentration. The detection of ATT molecules on the copper surface by Raman spectroscopy indicated that inhibition of copper corrosion is achieved by strong adsorption of ATT molecules onto the copper surface. [Copyright &y& Elsevier]

Abstract: Symbiotic cnidarians are marine invertebrates harboring photosynthesizing microalgae (named zooxanthellae), which produce great amounts of oxygen and free radicals upon illumination. Studying antioxidative balance is then crucial to understanding how symbiotic cnidarians cope with ROS production. In particular, it is suspected that oxidative stress triggers cnidarian bleaching, i.e., the expulsion of zooxanthellae from the animal host, responsible for symbiotic cnidarian mass mortality worldwide. This study therefore investigates catalase antioxidant enzymes and their role in bleaching of the temperate symbiotic sea anemone Anemonia viridis. Using specific separation of animal tissues (ectoderm and endoderm) from the symbionts (zooxanthellae), spectrophotometric assays and native PAGE revealed both tissue-specific and activity pattern distribution of two catalase electrophoretypes, E1 and E2. E1, expressed in all three tissues, presents high sensitivity to the catalase inhibitor aminotriazole (ATZ) and elevated temperatures. The ectodermal E1 form is responsible for 67% of total catalase activity. The E2 form, expressed only within zooxanthellae and their host endodermal cells, displays low sensitivity to ATZ and relative thermostability. We further cloned an ectodermal catalase, which shares 68% identity with mammalian monofunctional catalases. Last, 6 days of exposure of whole sea anemones to ATZ (0.5 mM) led to effective catalase inhibition and initiated symbiont expulsion. This demonstrates the crucial role of this enzyme in cnidarian bleaching, a phenomenon responsible for worldwide climate-change-induced mass mortalities, with catastrophic consequences for marine biodiversity. [Copyright &y& Elsevier]

Abstract: SmCAR (Schistosoma mansoni constitutive androstane receptor) is a schistosome homologue of the CAR/PXR/VDR group of nuclear receptors. The P box sequence in the DNA binding domain (DBD) of SmCAR, which is essential in determining the DNA binding specificity of nuclear receptors, is different from its vertebrate homologues. Previous data demonstrates that SmCAR binds to a hormone response element containing a single half site AGTGCA as a monomer. SmRXR1 and SmRXR2 are two S. mansoni homologues of vertebrate retinoid X receptors (RXRs). RXRs usually heterodimerize with various nuclear receptors. Yeast-two hybrid analyses, in vitro pull-down and co-immunoprecipitation assays demonstrated that SmCAR interacts with SmRXR1 but not SmRXR2. Using chimeras consisting of the DBD of SmCAR and the ligand binding domain (LBD) of mouse (m) CAR, we show that despite a different P box, SmCAR DBD shares DNA binding specificity with mCAR. However, the SmCAR DBD does exhibit some of the DNA binding properties specific to SmCAR. Studies of the chimeras also demonstrated that the SmCAR DBD is able to heterodimerize with the DBD of human RXR, allowing high affinity DNA binding. Based on this study and previous results, we conclude that SmCAR may recognize its cognate hormone response element via two mechanisms: binding to DNA monomerically or heterodimerizing with SmRXR1. We also demonstrate that a transcription activation function-1 (AF-1) is located in the SmCAR A/B domain. [Copyright &y& Elsevier]

Abstract: A thermoplastic elastomer having supramolecular hydrogen bonded network was prepared by the melt mixing of maleated ethylene propylene diene rubber and maleated high density polyethylene in presence of 3-amino-1,2,4-triazole (ATA), which acts as a coupling agent. The hydrogen bonded network formation in the blend system enhanced the physical properties of the blend. The storage modulus and glass transition temperature of the elastomer–plastic blend containing ATA was found to be increased as compared to the blend without ATA. It was observed that polyblends containing ATA exhibit a rubbery plateau above the melting temperature of the maleated high density polyethylene. Reprocessability study confirmed the thermoplastic elastomeric nature of the polyblend system. [Copyright &y& Elsevier]

Abstract: A FTZ-F1-related orphan nuclear receptor SmFTZ-F1α was previously identified from Schistosoma mansoni. The deduced SmFTZ-F1α protein contains a highly conserved DNA binding domain (DBD, C domain), a less conserved ligand binding domain (LBD, E domain) and three highly variable regions, the N-terminal A/B domain (108aa), a large hinge region (D domain, 1027aa) and an F domain (220aa). Herein, we characterize the DNA binding properties and the transactivation activity of SmFTZ-F1α. In in vitro assays, SmFTZ-F1α bound as a monomer to a response element (FF1RE: TCAAGGTCA) recognized by mammalian steroidogenic factor 1 (SF-1), and to related sequences (p14: TTAAGGTCA and SmFF1a-2: CGAAGGTCA) derived from known schistosome gene promoters. Competition assays with p14 oligonucleotides containing a single mutation at each nucleotide position defined the optimum DNA sequence required for SmFTZ-F1α binding. The optimal consensus sequence for SmFTZ-F1α binding is TN(A/G)AGGTC(A/G) (N: any base). This sequence is similar but not identical to the SF-1 response element (SFRE) consensus sequence [(T/C)CAAGG(T/C)C(A/G)]. By performing yeast one-hybrid assays, the ability of SmFTZ-F1α to bind productively to a p14-derived 9-base pair sequence was demonstrated in vivo. The ability of the full-length SmFTZ-F1α to transactivate reporter gene expression was shown to be A/B domain-dependent in a yeast system. In addition, the hinge region contained an unexpected activation function (AF) domain, termed AF-3, while no transactivation activity was detected within the E/F domain. This AF-3 region (from aa 982 to aa 1110) revealed a strong autonomous transactivation activity, which was masked when it was present in the full-length SmFTZ-F1α. Taken together, our results suggest that SmFTZ-F1α possesses the characteristic DNA binding specificity of FTZ-F1 subfamily members and the capacity to transactivate a reporter gene. [Copyright &y& Elsevier]

Abstract: Cardiovascular disease (CVD) is a human health crisis that remains the leading cause of death worldwide. The cytochrome P450 (CYP) class of enzymes are key metabolizers of both xenobiotics and endobiotics. Many CYP enzyme families have been identified in the heart, endothelium and smooth muscle of blood vessels. Furthermore, mounting evidence points to the role of endogenous CYP metabolites, such as epoxyeicosatrienoic acids (EETs), hydroxyeicosatetraenoic acids (HETEs), prostacyclin (PGI2), aldosterone, and sex hormones, in the maintenance of cardiovascular health. Emerging science and the development of genetic screening have provided us with information on the differences in CYP expression among populations and groups of individuals. With this information, a link between CYP expression and activity and CVD, such as hypertension, coronary artery disease (CAD), myocardial infarction, heart failure, stroke, and cardiomyopathy and arrhythmias, has been established. In fact many currently used therapeutic modalities in CVD owe their therapeutic efficacy to their effect on CYP metabolites. Thus, the evidence for the involvement of CYP in CVD is numerous. Concentrating on treatment modalities that target the CYP pathway makes ethical sense for the affected individuals and decreases the socioeconomic burden of this disease. However, more research is needed to allow the integration of this information into a clinical setting. [Copyright &y& Elsevier]

Abstract: For the first time a monosaccharide (methyl α-d-mannopyranoside) has been used as starting material for the synthesis of novel σ-receptor ligands. The hept-3-ulopyranoside dimethyl ketals 14 and 15 were obtained from the nitrile 7 via two synthetic routes. After selective hydrolysis of the ketone dimethyl acetal, various amino substituents were introduced into position 3. High σ1-receptor affinity and selectivity was attained with equatorially arranged amino substituents in position 3 and a dichlorophenylacetamide moiety in position 7. The anomeric mixture of dimethylamines 26α/β displayed the highest σ1-receptor affinity (K i =21nM) within this small series of test compounds. [Copyright &y& Elsevier]

Abstract: A series of 3-amino-1,2,4-benzotriazine-1,4-dioxide derivatives 1 have been synthesized and evaluated for their cytotoxic activity in vitro against human leukemia cell lines: Molt-4, K562, HL60, human liver cancer cell Hep-G2, human prostate cancer cell PC-3 in hypoxia. Most of the compounds showed more potent activity than TPZ. Compounds 1i and 1m displayed encouraging superior activity against Molt-4 and HL-60 cell lines. Three potential derivatives received the test of the activity in hypoxia and in normoxia against Molt-4 and HL-60 cell lines and showed obvious hypoxia selectivity. Further mechanism study revealed that the cytotoxic activities of compounds 1i and 1k in Molt-4 cells might be mediated by modulation of p53 protein expression and mitochondrial membrane potential (ΔΨ m). [Copyright &y& Elsevier]

Abstract: Ethanol is a well-established developmental toxicant; however, the molecular and cellular mechanism(s) of toxicity remains unclear. It has been suggested that ethanol metabolism leads to oxidative stress resulting in an increase in cell death. Alcohol developmental toxicity has not been well studied in zebrafish; however, zebrafish represent an excellent vertebrate model for investigating and understanding normal and aberrant development. To evaluate ethanol metabolism dependent toxicity, chemical inhibitors of the ethanol metabolizing enzymes were utilized. Embryos co-exposed to ethanol and a combination of ethanol metabolism inhibitors led to a significant increase in the occurrence of pericardial edema. Further, in the presence of the inhibitor mixture there was an increase in developmental malformations at lower ethanol concentrations. Cell death has been implicated as a potential explanation for ethanol-dependent toxicity. Using cell death assays, ethanol significantly increased embryonic cell death. To determine if oxidative stress underlies cardiovascular dysfunction, embryos were co-exposed to ethanol and several antioxidants. The antioxidants, glutathione and lipoic acid, partially attenuated the incidence of pericardial edema. The effectiveness of the antioxidants to protect the embryos from ethanol-induced cell death was also evaluated. The antioxidants provided no protection against cell death. Thus, ethanol-mediated pericardial edema and cell death appear to be mechanistically distinct. [Copyright &y& Elsevier]

Abstract: In reactions of (2,3-anti)-3-amino-1,2-diols with diphosgene and phosgene and their conversion into 1,3-oxazolidin-2-ones, some differences in the stereochemistry of the reactions have been found with these two reagents. The reactions with phosgene afforded the expected cis-oxazolidinones, and in the reaction with diphosgene under the same reaction conditions, the trans-oxazolidinones were also obtained. [Copyright &y& Elsevier]

Abstract: A heterocyclic amine, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) is one of the potent food-borne dietary carcinogens derived mainly from burnt meat products. In the present study, we investigated the immunosuppressive effect of Trp-P-1 on the blastogenesis of lymphocytes prepared from spleen and thymus of Balb/c mice. Trp-P-1 inhibited, in a dose-dependent manner, proliferation of splenocytes in response to a B-cell mitogen, lipopolysaccharide and of both splenocytes and thymocytes in response to T-cell mitogens, concanavalin A and phytohemagglutinin, or non-receptor-mediated stimuli, phobol 12-myristate 13-acetate/ionomycin. Interestingly, Trp-P-1-inhibited proliferation in the splenocytes was restored almost completely by N-acetyl-l-cysteine (NAC) and partially by glutathione (GSH), whereas no effect was found when superoxide dismutase and catalase were used. Moreover, Trp-P-1 enhanced the mitogen-induced NF-κB binding activity to its cognate binding sequences, which is known to be mediated by intracellular reactive oxygen species (ROS) generation. Collectively, these results suggest that the immunosuppressive effect of Trp-P-1 is mediated by suppressing blastogenesis of lymphocytes via intracellular generation of ROS sensitive to NAC and/or GSH. [Copyright &y& Elsevier]

The overexpression of LIM-only protein 2 (LMO2) in T-cells, as a result of chromosomal translocations, retroviral insertion during gene therapy, or in transgenic mice models, leads to the onset of T-cell leukemias. LMO2 comprises two protein-binding LIM domains that allow LMO2 to interact with multiple protein partners, including LIM domain-binding protein 1 (Ldb1, also known as CLIM2 and NLI), an essential cofactor for LMO proteins. Sequestration of Ldb1 by LMO2 in T-cells may prevent it binding other key partners, such as LMO4. Here, we show using protein engineering and enzyme-linked immunosorbent assay (ELISA) methodologies that LMO2 binds Ldb1 with a twofold lower affinity than does LMO4. Thus, excess LMO2 rather than an intrinsically higher binding affinity would lead to sequestration of Ldb1. Both LIM domains of LMO2 are required for high-affinity binding to Ldb1 (K D=2.0×10−8 M). However, the first LIM domain of LMO2 is primarily responsible for binding to Ldb1 (K D=2.3×10−7 M), whereas the second LIM domain increases binding by an order of magnitude. We used mutagenesis in combination with yeast two-hybrid analysis, and phage display selection to identify LMO2-binding “hot spots” within Ldb1 that locate to the LIM1-binding region. The delineation of this region reveals some specific differences when compared to the equivalent LMO4:Ldb1 interaction that hold promise for the development of reagents to specifically bind LMO2 in the treatment of leukemia. [Copyright &y& Elsevier]

Abstract: Hydroxyurea is an approved treatment for sickle cell disease. Oxidation of hydroxyurea results in the formation of nitric oxide (NO), which also has drawn considerable interest as a sickle cell disease therapy. Although patients on hydroxyurea demonstrate elevated levels of nitric oxide-derived metabolites, little information regarding the site or mechanism of the in vivo conversion of hydroxyurea to nitric oxide exists. Chemiluminescence detection experiments show the ability of crude rat liver homogenate to convert hydroxyurea to nitrite/nitrate, evidence for NO production. Nitrite/nitrate form at therapeutic concentrations of hydroxyurea in a clinically relevant time frame. Electron paramagnetic resonance (EPR) studies show the formation of iron nitrosyl complexes during this incubation and experiments with labeled hydroxyurea show the NO derives from the drug. Gas chromatography–mass spectrometry measurements indicate the hydrolysis of hydroxyurea to hydroxylamine in this system. Incubation of hydroxylamine with crude rat liver homogenate also generates nitrite/nitrate and iron nitrosyl complexes. A line of evidence including inhibitor studies, EPR spectroscopy, and nitrite/nitrate detection identifies catalase as a possible oxidant for the conversion of hydroxyurea to NO. These results reveal the ability of liver tissue to convert hydroxyurea to nitric oxide and provide insight into the metabolism of this drug. [Copyright &y& Elsevier]

Background/Aims: In liver diseases, reactive oxygen species (ROS) are involved in cell death and liver injury, but the mechanisms are not completely elucidated. To elucidate the mechanisms of hepatocyte cell death induced by the ROS superoxide anions and hydrogen peroxide, primary cultures of hepatocytes were exposed to the superoxide anion donor menadione (10–50μmol/L) or H2O2 (1–5mmol/L). Hepatocytes were also treated with caspases and MAPKs inhibitors, superoxide dismutase (PEG-SOD) and SNAP, a nitric oxide donor. Apoptosis was determined by measuring caspase-9, -6, -3 activation and cleaved PARP, and necrotic cell death by Sytox Green staining. Results: (1) Menadione (50μmol/L) induces JNK phosphorylation, caspase-9, -6, -3 activation, PARP cleavage and apoptosis. Superoxide anions-induced apoptosis is dependent on JNK activity. Menadione (50μmol/L) induces the phosphorylation of ERK1/2 and this attenuates cell death. (2) H2O2 increases necrotic cell death at high concentration or when H2O2 detoxification is impaired. H2O2 does not activate MAPKs signalling. (3) PEG-SOD prevents ERK1/2-, JNK- phosphorylation, caspase activation and apoptosis induced by menadione. Glutathione depletion increases menadione-induced apoptosis. (4) SNAP abolishes menadione-induced apoptosis but increases necrotic cell death. Conclusions: In normal hepatocytes, superoxide anions-induced caspase activation and apoptosis is dependent on JNK activity and totally abolished by superoxide scavengers. [Copyright &y& Elsevier]