Synthesis of magnesium titanate nanocrystallites from a cheap and water-soluble single source precursor

Pure nanocrystallite magnesium titanate (MgTiO₃) was conveniently synthesized by thermal decomposition of a cheap and water-soluble heterobimetallic single source precursor [Mg(H₂O)₅]₂[Ti₂(O₂)₂O(NC₆H₆O₆)₂]·7H₂O at low temperature. This single source precursor was obtained in high yield and in a crystalline form from the quaternary system of MgO-Ti(OC₄H₉)₄-H₂O₂-H₃nta (H₃nta = nitrilotriacetic acid) at pH 4.0. It was characterized by elemental analysis, IR spectrum, NMR, thermal gravimetric analysis and X-ray single-crystal diffraction. The morphology, microstructure, and crystallinity of the resulting MgTiO₃ materials have been characterized by transmission electron microscopy and X-ray diffraction. The TEM image of the resulting MgTiO₃ powders only consists of the nano-scale crystallites with the crystalline size of 30-100 nm.     

Proterguride, a highly potent dopamine receptor agonist promising for transdermal administration in Parkinson's disease: interactions with alpha(1)-, 5-HT(2)- and H(1)-receptors

Dopamine receptor agonists play an important role in the treatment of Parkinson's disease and hyperprolactinemic conditions. Proterguride (n-propyldihydrolisuride) was already reported to be a highly potent dopamine receptor agonist, thus its action at different non-dopaminergic monoamine receptors, alpha(1A/1B/1D), 5-HT(2A/2B)- and histamine H(1), was investigated using different functional in vitro assays. The drug behaved as an antagonist at alpha(1)-adrenoceptors without the ability to discriminate between the subtypes (pA(2) values: alpha(1A) 7.31; alpha(1B) 7.37; alpha(1D) 7.35) and showed antagonistic properties at the histamine H(1) receptor. In contrast, at serotonergic receptors (5-HT(2A), 5-HT(2B)) proterguride acted as a partial agonist. The drug stimulated 5-HT(2A) receptors of rat tail artery in lower concentrations than 5-HT itself but failed to evoke comparable efficacy (proterguride: pEC(50) 8.34, E(max) 53% related to the maximum response to 5-HT; 5-HT: pEC(50) 7.03). Agonism at 5-HT(2B) receptors is presently considered to be involved in drug-induced valvular heart disease. Activation of 5-HT(2B) receptors in porcine pulmonary arteries by proterguride (pEC(50) 7.13, E(max) 49%; E(max) (5-HT) 69%), however, occurred at concentrations much higher than plasma concentrations achieving dopaminergic efficacy in humans. The results are discussed focussing on the relevance of action at 5-HT(2B) receptors as well as their significance for a transdermal administration of proterguride. Since it is well accepted that pulsatile dopaminergic stimulation is associated with treatment-related motor complications in the dopaminergic therapy of Parkinson's disease, the transdermal route of administration is of great clinical interest due to the possibility to achieve constant plasma concentrations.     

Deposition of iron titanate/titania ceramic composite thin films from a single molecular precursor

A heterobimetallic single molecular precursor, [Fe₂Ti₄(μ-O)₆(TFA)₈(THF)₆] (1) [TFA = trifluoroacetate, THF = tetrahydrofuran], was synthesized by the simple reaction of [Fe₃O(OAc)₆(H₂O)₃]NO₃·4H₂O [OAc = acetato] with tetrakis(2-ethoxyethanalato)titanium(IV) in the presence of trifluoroacetic acid in THF. The synthesized precursor was analyzed by melting point, CHN analysis, FTIR, single crystal X-ray diffraction and thermogravimetric analysis. Complex (1) crystallizes in the orthorhombic space group Pca2₁ with cell dimensions a = 19.2114(14), b = 20.4804(15) and c = 17.2504(12) Å, and the complex undergoes thermal decomposition at 490 °C to give a residual mass corresponding to an Fe₂TiO₅-TiO₂ composite mixture. The synthesized precursor was utilized for deposition of Fe₂TiO₅-TiO₂ composite thin films by aerosol-assisted chemical vapor deposition (AACVD) on glass substrates at 500 °C using argon as the carrier gas. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray powder diffraction (XRD) analyses of the thin films suggest the formation of good quality crystalline thin films of an Fe₂TiO₅-TiO₂ composite with an average grain size of 0.105-0.120 μm.     

Characterization of ThOX proteins as components of the thyroid H(2)O(2)-generating system

We have recently cloned two thyroid-specific cDNAs encoding new members of the NADPH oxidase family. ThOX1 and ThOX2 proteins are colocalized with thyroperoxidase at the apical membrane of human thyroid cells. In the present study we have determined their subcellular localization and maturation in relation to their enzymatic activity. A majority of ThOX proteins accumulated inside the cell and only a small fraction was expressed at the surface. Western blots demonstrated that ThOX's are glycoproteins of 180,000 and 190,000. When totally deglycosylated the molecular weight of both ThOX1 and ThOX2 drops to 160,000. Ca(2+) stimulates the basal H(2)O(2) generation in PC Cl3 cells at a level corresponding to 20% of the leukocyte H(2)O(2) production stimulated by PMA. Nonthyroid cell lines transfected with ThOX1 and ThOX2 show only a single immunoreactive band in Western blot analysis, corresponding to the protein of 180,000. This "immature" protein remains exclusively intracellular and does not present any enzymatic activity. This is not modified by coexpression of thyroperoxidase and p22(Phox). Transfection of ThOX cDNAs into PLB-XCGD cells does not reconstitute their NADPH oxidase activity. We conclude that (1) the thyroid contains some elements of the leukocyte H(2)O(2)-generating system but not all of them; (2) ThOX's are predominantly or exclusively located inside the cell in thyrocytes or in transfected cells, respectively, and as such they are inactive; (3) ThOX's cannot replace gp91(Phox) in the leukocyte; and (4) the thyroid H(2)O(2)-generating system is analogous to the leukocyte system with regard to ThOX's and gp91(Phox) but very different in other aspects. Additional thyroid-specific components are probably required to get complete protein processing and full enzymatic activity in the thyroid.     

Characterization of a dinuclear Mn(II) tri(μ-carboxylato) complex with the hindered hydrotris(3,5-diisopropyl-1-pyrazolyl)borate (=TpPr2) ligand: intramolecular hydrogen bonding interaction between the protonated TpPr2 and Mn-coordinating carboxylate ligands

A dinuclear Mn(II) di(μ-hydroxo) complex having hydrotris(3,5-diisopropyl-1-pyrazolyl)borate (=Tp^iPr₂) reacted with benzoic acid to yield a dinuclear Mn(II) tri(μ-carboxylato) complex, Tp^iPr₂Mn-(μ-OBz)₃-Mn(Tp^iPr₂H). X-ray crystallography reveals the unsymmetrical coordination environments for the manganese centers. One of the two Tp^iPr₂ ligands, which bound to the five-coordinated Mn center, is protonated by the action of the third carboxylic acid and the resulting non-Mn-binding N–H moiety forms an intramolecular hydrogen bond with the oxygen donor of a carboxylate ligand. Steric congestion in the bimetallic core results in the large separation of the manganese centers bridged by the syn-anti carboxylate ligand.     

Oriented solids as a colloid suspension in nematic liquid crystal – New tool for IR-spectroscopic and structural elucidation of inorganic compounds and glasses

Possibilities of the linear-polarized infrared (IR-LD) spectroscopy of oriented colloid suspensions in nematic liquid crystals, for structural and local structural elucidation for first time are demonstrated of inorganic compounds and glasses. The advantages of the method for tellurite and borate glasses are shown. The IR-band assignment of the typical local structural units in the glasses are proposed by a comparison with the IR-characteristics of appropriate crystalline analogues as α-TeO₂, V₂O₅, MoO₃ · H₂O and its high temperature form. The IR-spectroscopic characteristics of BO₃, BO₄ and boroxol ring are elucidated, using crystalline β-BaB₂O₄, SrB₄O₇, H₃BO₃ and B₂O₃ as model systems, where the structural moieties have been refined by single crystal X-ray diffraction.     

The predicted transmembrane fragment 17 of the human multidrug resistance protein 1 (MRP1) behaves as an interfacial helix in membrane mimics

The human multidrug resistance protein MRP1 (or ABCC1) is one of the most important members of the large ABC transporter family, in terms of both its biological (tissue defense) and pharmacological functions. Many studies have investigated the function of MRP1, but structural data remain scarce for this protein. We investigated the structure and dynamics of predicted transmembrane fragment 17 (TM17, from Ala₁₂₂₇ to Ser₁₂₅₁), which contains a single Trp residue (W₁₂₄₆) involved in MRP1 substrate specificity and transport function. We synthesized TM17 and a modified peptide in which Ala₁₂₂₇ was replaced by a charged Lys residue. Both peptides were readily solubilized in dodecylmaltoside (DM) or dodecylphosphocholine (DPC) micelles, as membrane mimics. The interaction of these peptides with DM or DPC micelles was studied by steady-state and time-resolved Trp fluorescence spectroscopy, including experiments in which Trp was quenched by acrylamide or by two brominated analogs of DM. The secondary structure of these peptides was determined by circular dichroism. Overall, the results obtained indicated significant structuring (∼50% α-helix) of TM17 in the presence of either DM or DPC micelles as compared to buffer. A main interfacial location of TM17 is proposed, based on significant accessibility of Trp₁₂₄₆ to brominated alkyl chains of DM and/or acrylamide. The comparison of various fluorescence parameters including λ_max, lifetime distributions and Trp rotational mobility with those determined for model fluorescent transmembrane helices in the same detergents is also consistent with the interfacial location of TM17. We therefore suggest that TM17 intrinsic properties may be insufficient for its transmembrane insertion as proposed by the MRP1 consensus topological model. This insertion may also be controlled by additional constraints such as interactions with other TM domains and its position in the protein sequence. The particular pattern of behavior of this predicted transmembrane peptide may be the hallmark of a fragment involved in substrate transport.     

Nischarin as a functional imidazoline (I1) receptor

Gene matching shows that Nischarin is a mouse homologue of human imidazoline receptor antisera-selective (IRAS) protein, a viable candidate of the imidazoline (I1) receptor. Nischarin and IRAS share the functions of enhancing cell survival, growth and migration. Bioinformatics modeling indicates that the IRAS and Nischarin may be transmembrane proteins and the convergence information raises the interesting possibility that Nischarin might serve as the I1-receptor. To test this hypothesis, we developed antibodies against the Nischarin protein, and conducted signal transduction (functional) studies with the I1-receptor agonist rilmenidine in the presence and absence of Nischarin antisense oligodeoxynucleotides (ODNs). NIH3T3 cells transfected with the Nischarin cDNA and incubated with the newly synthesized antibody expressed a 190 kD band. The antibody identified endogenous Nischarin in differentiated PC12 cells around 210 kD, which is consistent with reported findings in other cells of neuronal origin. The immunoflourescence findings showed the targeted protein to be associated with the cell membrane in PC12 cells. Nischarin ODNs abolished the expression of Nischarin in PC12 cells. Equally important, the Nischarin ODNs eliminated the production of MAPK(p42/44), a recognized signal transduction product generated by I1-receptor activation in differentiated PC12 cells. Together, the present findings suggest that Nischarin may serve as the functional I1-receptor or at least share a common signaling pathway in the differentiated PC12 cells.     

Haemocyanin oxygen binding and the physiological ecology of a range of talitroidean amphipods (Crustacea)

Summary Haemolymph PO₂ and pH of two amphipod species, Apohyale pugettensis (aquatic) and Megalorchestia californiana (semi-terrestrial) in vivo were examined during immersion and emersion at 15 and 25°C, and also after activity in air at 15°C. For M. californiana arterial O₂ tensions were higher in air than in water. This situation was reversed in A. pugettensis, although all O₂ tensions measured for both species were comparatively high. No arterial-venous PO₂ difference was apparent in the haemolymph of quiescent M. californiana. Haemocyanin (Hc) was 100% saturated in vivo only in the following; A. pugettensis in water (15 and 25°C) and air (15°C), and M. californiana in air (15°C). The Hc of both species becomes important in O₂ transport during activity; under such circumstances the haemolymph of M. californiana delivered more O₂ to the tissues than did that of A. pugettensis, despite the greater O₂ content of the latter. The animals studied here may exhibit a stage (size class?) where cutaneous gas exchange is sufficient for resting aerobic metabolism while specialized respiratory carriers (and respiratory structures) are important in meeting the increased aerobic demands of activity or environmental stress.Abbreviations Hc haemocyanin - PO₂ partial pressure of oxygen     

Investigation of TiO2 anatase (1 0 1), (1 0 0) and (1 1 0) facets as immobilizer for a potential anticancer RNA aptamer: a classical molecular dynamics simulation

One of the most outstanding properties of TiO₂ nanosheets is their lack of harmful effects on the public health and environment, which makes them an appropriate agent for medical applications such as drug delivery. Interaction of an RNA aptamer with (1 0 1), (1 0 0) and (1 1 0) surfaces of TiO₂ anatase were investigated using the molecular dynamics simulation. The structural parameters including root-mean-square deviation and fluctuation, and the distance between the center-of-mass of RNA aptamer and the considered surfaces were discussed in detail. Besides, the effect of water between adsorbed aptamer and surface was investigated and analyzed by the help of dipole moment orientation, hydrogen bonds and density profile of these water molecules. Analysis of the structural parameters and interaction energies shows that the (1 1 0) surface is energetically more favorable for the adsorption of considered RNA aptamer than the (1 0 0) and (1 0 1) surfaces. Consequently, our results suggest a great potential of (1 1 0) surface of TiO₂ as an efficient candidate for drug delivery applications.     

A novel function of peroxiredoxin 1 (Prx-1) in apoptosis signal-regulating kinase 1 (ASK1)-mediated signaling pathway

We report a novel function of peroxiredoxin-1 (Prx-1) in the ASK1-mediated signaling pathway. Prx-1 interacts with ASK1 via the thioredoxin-binding domain of ASK1 and this interaction is highly inducible by H2O2. However, catalytic mutants of Prx1, C52A, C173A, and C52A/C173A, could not undergo H2O2 inducible interactions, indicating that the redox-sensitive catalytic activity of Prx-1 is required for the interaction with ASK1. Prx-1 overexpression inhibited the activation of ASK1, and resulted in the inhibition of downstream signaling cascades such as the MKK3/6 and p38 pathway. In Prx-1 knockdown cells, ASK1, p38, and JNK were quickly activated, leading to apoptosis in response to H2O2. These findings suggest a negative role of Prx-1 in ASK1-induced apoptosis.     

Toxicity of the mycotoxins fumonisins B1 and B2 and Alternaria alternata f. sp. lycopersici toxin (AAL) in cultured mammalian cells

Fumonisins B₁ and B₂ and AAL toxin are a series of structurally related mycotoxins. Fumonisins B₁ and B₂, produced by Fusarium moniliforme Sheldon induce toxic hepatitis and hepatomas in rats and leukoencephalomalacia in horses. The cancer-promotion assay which has been used to guide their purification is slow and consumes large amounts of sample. We have examined a series of cultured mammalian cell lines in order to develop a more rapid and sensitive bioassay system, which may be useful for examining structure-activity relationships and the mechanism(s) of action of these toxins. Of 9 rat hepatoma cell lines tested, all except the two most de-differentiated lines were sensitive to the three toxins, with a toxic response visible by 48 h. Approximate IC₅₀ values for the most sensitive hepatoma line, H4TG, were 4, 2 and 10 g/ml for fumonisins B₁, B₂ and AAL toxin, respectively in 100 l cultures. Among 15 cell lines from other sources, only MDCK dog kidney epithelial cells were sensitive (IC₅₀ = 2.5, 2 and 5 g/ml, respectively). Studies in co-cultures of sensitive and insensitive cell lines and in cultures of a sensitive cell line over a range of cell densities indicated that cytotoxicity of fumonisins B₁ and B₂ does not involve metabolite activation to a derivative stable enough to diffuse to adjacent cells.Abbreviations AAL toxin Alternaria alternata f. sp. lycopersici toxin - IC₅₀ concentration giving 50% inhibition of cell proliferation     

Model studies on a synthetically facile series of N-substituted phenyl-N′-pyridin-3-yl ureas leading to 1-(3-pyridylcarbamoyl) indolines that are potent and selective 5-HT2C/2B receptor antagonists

A model series of 5-HT_2C antagonists have been prepared by rapid parallel synthesis. These N-substituted phenyl-N′-pyridin-3-yl ureas were found to have a range of 5-HT_2C receptor affinities and selectivities over the closely related 5-HT_2A receptor. Extrapolation of simple SAR, derived from this set of compounds, to the more active but synthetically more complex 1-(3-pyridyl-carbamoyl)indoline series allowed us to target optimal substitution patterns and identify potent and selective 5-HT_2C/2B antagonists.     

c-Jun NH2-terminal kinase decreases ubiquitination and promotes stabilization of p21(WAF1/CIP1) in K562 cell

Proteasome-dependent degradation of regulatory proteins is a known mechanism of cell cycle control. p21(WAF1/CIP1) (p21), a negative regulator of the cell division cycle, exhibits proteasome-sensitive turnover and ubiquitination. In the present study, we analyzed the regulatory effects of JNK1 on p21 protein accumulation in p53 null K562 cells. We found that JNK1 (wild type, WT) mediated H(2)O(2)-induced p21 protein up-regulation. Over-expression of JNK1 (WT) could elevate endogenous p21 protein level but did not affect p21 mRNA level and also prolong the p21 half-life as well as inhibited the p21 ubiquitination. These findings indicated that JNK1 could regulate cellular p21 level via inhibiting ubiquitination of p21, which provided a new insight for analyzing the regulatory effect of JNK after stress.     

Germanium tetra(tertiary butoxide): Synthesis, structure and its utility as a precursor for the preparation of europium doped germanium oxide nanoparticles

Germanium tetra(tertiary butoxide), [Ge(O^tBu)₄], has been prepared by the reaction of GeCl₄ with KOBu^t in benzene. It is a monomeric crystalline solid having a distorted tetrahedral configuration, defined by the coordination of four OBu^t groups around germanium atom. The TG analysis showed that the compound is thermally stable and volatilizes at around 130 °C. Europium doped and un-doped germanium oxide nanoparticles were prepared based on the urea hydrolysis of Ge(O^tBu)₄/Eu(OOCCH₃)₃ in ethylene glycol medium at 150 °C followed by heating the resulting product at 750 °C. The nanoparticles were characterized by XRD, TEM and PL measurements. The europium doped nanoparticles, which were nearly monodispersed (∼30 nm), showed luminescence and the Eu³⁺ ions were occupying the surface of the GeO₂ nanoparticles.     

In vitro and in vivo pharmacological profile of 4-(4-fluorobenzylidene)-1-[2-[5-(4-fluorophenyl)-1H-pyrazol-4-yl] ethyl] piperidine (NRA0161)

Atypical antipsychotic properties of 4-(4-fluorobenzylidene)-1-[2-[5-(4-fluorophenyl)-1H-pyrazol-4-yl]ethyl] piperidine (NRA0161) were investigated by in vitro receptor affinities, in vivo receptor occupancies and findings were compared with those of risperidone and haloperidol in rodent behavioral studies. In in vitro receptor binding studies, NRA0161 has a high affinity for human cloned dopamine D(4) and 5-HT(2A) receptor with Ki values of 1.00 and 2.52 nM, respectively. NRA0161 had a relatively high affinity for the alpha(1) adrenoceptor (Ki; 10.44 nM) and a low affinity for the dopamine D(2) receptor (Ki; 95.80 nM). In in vivo receptor binding studies, NRA0161 highly occupied the 5-HT(2A) receptor in rat frontal cortex. In contrast, NRA0161 did not occupy the striatal D(2) receptor. In behavioral studies, NRA0161, risperidone and haloperidol antagonized the locomotor hyperactivity in mice, as induced by methamphetamine (MAP). At a higher dosage, NRA0161, risperidone and haloperidol dose-dependently antagonized the MAP-induced stereotyped behavior in mice and NRA0161 dose-dependently and significantly induced catalepsy in rats. The ED(50) value in inhibiting the MAP-induced locomotor hyperactivity was 30 times lower than that inhibiting the MAP-induced stereotyped behavior and 50 times lower than that which induced catalepsy.These findings suggest that NRA0161 may have atypical antipsychotic activities yet without producing extrapyramidal side effects.     

Sensitivity of cultured rat hepatocytes to aflatoxin B1 and benzo(a)pyrene

Summary We have tested the sensitivity of a cloned rat hepatocyte line, RL-PR-C, to aflatoxin B₁ and benzo(a)pyrene as a function of population-doubling level. The cells were much more sensitive to the cytotoxic action of these agents subsequent to 230 population doublings. This sensitivity corresponded to the enhanced inducibility of arylhydrocarbon hydroxylase activity by 3-methylcholanthrene. Supported by Grants CA 21258 and CA 12056 from the National Cancer Institute.