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Loss of salt-inducible kinase 1 (SIK1) triggers an increase in blood pressure (BP) upon a chronic high-salt intake in mice. Here, we further addressed the possible early mechanisms that may relate to the observed rise in BP in mice lacking SIK1. SIK1 knockout (sik1−/−) and wild-type (sik1+/+) littermate mice were challenged with either a high-salt (8% NaCl) or control (0.3% NaCl) diet for 7 days. Systolic BP was significantly increased in sik1−/− mice after 7 days of high-salt diet as compared with sik1+/+ mice and to sik1−/− counterparts on a control diet. The renin–angiotensin–aldosterone system and the sympathetic nervous system were assayed to investigate possible causes for the increase in BP in sik1−/− mice fed a 7-day high-salt diet. Although no differences in serum renin and angiotensin II levels were observed, a reduction in aldosterone serum levels was observed in mice fed a high-salt diet. Urinary L-DOPA and noradrenaline levels were significantly increased in sik1−/− mice fed a high-salt diet as compared with sik1−/− mice on a control diet. Similarly, the activity of dopamine β-hydroxylase (DβH), the enzyme that converts dopamine to noradrenaline, was significantly increased in the adrenal glands of sik1−/− mice on a high-salt intake compared with sik1+/+ and sik1−/− mice on a control diet. Treatment with etamicastat (50 mg/kg/day), a peripheral reversible DβH inhibitor, administered prior to high-salt diet, completely prevented the systolic BP increase in sik1−/− mice. In conclusion, SIK1 activity is necessary to prevent the development of salt-induced high blood pressure and associated SNS overactivity.

Since 1987, the CEA’s Committee for the establishment of analysis methods (CETAMA) has regularly implemented interlaboratory comparisons, entitled “evaluation of the quality results of analysis in the nuclear industry” (EQRAIN). Notably, the EQRAIN U and EQRAIN Pu interlaboratory comparisons assess proficiency in measuring a mass content of uranium or plutonium in reference solutions. This paper presents the results of measurement uncertainty assessments from EQRAIN U and EQRAIN Pu comparisons over 20 years of exercises (1997–2016). The mathematical approach developed in this work allowed to estimate the impact of short-term systematic and random errors to the overall uncertainty of each analytical method used in the interlaboratory comparison program. This statistical analysis shows a good consistency between measurement uncertainty values from EQRAINs and the measurement uncertainty target values established by the International Atomic Energy Agency for nuclear material balances (ITVs-2010).

Bacillus amyloliquefaciens MEP218 is a native isolate with a broad spectrum of antifungal activity against plant pathogenic fungi. The ability of strain MEP218 to antagonize phytopathogens is due to the production of cyclic lipopeptides (CLPs). In this work, different carbon (C) and nitrogen (N) sources and C to N ratios were evaluated in order to improve both, biomass and CLPs production by strain MEP218. Among the C and N sources and C to N ratios tested, glucose and NH4NO3 at the C to N ratio of 10:1 enhanced significantly biomass and CLPs yield. Moreover, CLPs produced in this medium exhibited higher antibacterial activity against Xanthomonas axonopodis pv. vesicatoria (Xav) than those obtained in the recommended medium for CLPs production. Interestingly, CLPs addition influenced the development of Xav biofilm on biotic and abiotic surfaces. A comparison of HPLC-chromatograms of CLPs obtained in the optimized medium versus the ones obtained in the recommended medium showed a notable increase of surfactin in the CLPs obtained in the optimized medium. Furthermore, two peaks with antibacterial activity against Xav, identified by mass spectrometry analysis as fengycins A and B, were detected in the CLPs from the strain MEP218, grown in the optimized culture medium. The results obtained in this work suggest that changes in C and N sources and C to N ratios affect the yield and type of CLPs produced by B. amyloliquefaciens MEP218. To the best of our knowledge, this is the first study to report the finding of fengycins with antibacterial activity. CLPs produced by the strain MEP218 are potential candidates for controlling bacterial spot disease in tomato and pepper. Fil: Medeot, Daniela Beatriz. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Biotecnología Ambiental y Salud - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Biotecnología Ambiental y Salud; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina Fil: Bertorello Cuenca, Magdalena. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina Fil: Liaudat, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina Fil: Alvarez, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina Fil: Flores Cáceres, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina Fil: Jofré, Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina

Four carbomethoxydiphenyl sulfone compounds are formed in the reaction of 4,4′-dibromo (I) and 4,4′-diiododiphenyl sulfone (II) with n-butyllithium in tetrahydrofuran at -60°C. Their mass and proton-nuclear megnetic resonance spectra are discussed.

In the original publication of the article, the values of u(s), u(r) and ITV for HKED were published incorrectly in Table 6.

To uncover the potential cardiovascular effects of human polymorphisms influencing transforming growth factor β1 (TGFβ1) expression, we generated mice with Tgfb1 mRNA expression graded in five steps from 10% to 300% normal. Adrenal expression of the genes for mineralocorticoid-producing enzymes ranged from 50% normal in the hypermorphs at age 12 wk to 400% normal in the hypomorphs accompanied with proportionate changes in plasma aldosterone levels, whereas plasma volumes ranged from 50% to 150% normal accompanied by marked compensatory changes in plasma angiotensin II and renin levels. The aldosterone/renin ratio ranged from 0.3 times normal in the 300% hypermorphs to six times in the 10% hypomorphs, which have elevated blood pressure. Urinary output of water and electrolytes are markedly decreased in the 10% hypomorphs without significant change in the glomerular filtration rate. Renal activities for the Na + , K + -ATPase, and epithelial sodium channel are markedly increased in the 10% hypomorphs. The hypertension in the 10% hypomorphs is corrected by spironolactone or amiloride at doses that do not change blood pressure in wild-type mice. Thus, changes in Tgfb1 expression cause marked progressive changes in multiple systems that regulate blood pressure and fluid homeostasis, with the major effects being mediated by changes in adrenocortical function.

The magnetic properties of hematite powders produced by a solid state nucleation-and-growth process are studied as a function of temperature T and applied field H. Independently of the temperature, there exists a soft magnetic contribution that is assigned to the canting of spins at the superficial shell of each particle and is not affected by the Morin transition. At 220

Because a newly described salt-inducible kinase 1 (SIK1) network is responsible for increases in active cell sodium transport in response to elevated intracellular sodium, we hypothesized that this network could mediate the effects of the mutant (hypertensive) form of alpha-adducin on Na,K-ATPase activity.Studies were performed in normotensive and hypertensive Milan rats and in a cell line of proximal tubule origin expressing transiently variants of alpha-adducin (human G460W/S586C; rat F316Y) that are associated with elevated blood pressure and result in increased Na,K-ATPase activity. Na,K-ATPase activity was determined as ouabain-sensitive rubidium transport.SIK1 activity (T182 phosphorylation) was significantly elevated in renal proximal tubule cells from Milan hypertensive rats (carrying a alpha-adducin mutation) when compared with normotensive controls. Similarly, SIK1 activity (T182 phosphorylation) was elevated in a normal renal proximal tubule cell line when transfected with the alpha-adducin variant carrying the human hypertensive mutation. Blocking the SIK1 network using negative mutants as well as different stages of its activation pathway prevented the effects induced by the hypertensive alpha-adducin.The SIK1 network may constitute an alternative target by which agents can modulate active sodium transport in renal epithelia and avoid the increases in systemic blood pressure that are associated with genetic mutations in the human alpha-adducin molecule.

First order reversal curves (FORCs) distributions are a powerful tool for investigating hysteresis and interactions in magnetic systems and have been widely applied. La–Co substitution in barium hexaferrites has also been extensively studied. The most effective substitution to improve the magnetic properties (coercive field and energy product) is given by x = y = 0.2 in the formula Ba 1 - x La x Fe 12 - y Co y O 19 . In this work, this stoichiometry is initially used to obtain a state where more than one phase is present. The magnetic behavior as a function of temperature was studied in order to have an insight into the magnetic interactions that originate a decrease in the magnetic performance of Ba hexaferrite magnets. The sample was structurally characterized by X-ray diffraction (XRD) and magnetically studied in a SQUID magnetometer. FORC distributions were used to study the dependence of the magnetic interactions with the temperature. FORC diagrams performed on the sample at different temperatures exhibit similar characteristics, such as the spread in the h c – h u plane and a spread out of the h c -axes. These features are interpreted in terms of exchange-interacting particles and dipolar interactions, respectively. As the temperature decreases, stronger interactions are noticed among hard and soft phases.

The selective catalytic oxidation of styrene with hydrogen peroxide was studied over Co–ZSM-5 catalysts which differ in the preparation methods. The catalysts were obtained from NH 4 + –ZSM-5 by wetness impregnation and ion-exchange techniques followed by different post-thermal treatments: oxidation and reduction. The characterization of acidic properties by FTIR of adsorbed pyridine revealed that new and strong Lewis sites (1452 cm −1 ), different from those characteristics of aluminum in the matrix (1456 cm −1 ) were generated by cobalt introduction. Styrene conversion shows an important increment over the exchanged samples as compared to the impregnated ones. This behavior may be explained by the high Lewis acid sites concentration. Benzaldehyde was the main product in all the samples under study. The samples’ magnetic properties were improved with the cobalt incorporation and the applied thermal treatments. The catalytic and magnetic properties of Co–ZSM-5 samples are discussed.

Co-containing molecular sieves with MFI structure was synthesized by the hydrothermal crystallization method and cobalt was incorporated in it by wet impregnation at different percentages. Thermal post-treatments were applied to Co-ZSM-5: calcination and reduction. X ray diffraction (XRD) and FTIR studies confirmed crystallinity, structure and orthorhombic symmetry of the obtained samples (Co-ZSM-5 calcined and Co-ZSM-5 reduced). The XRD, Raman spectroscopy, SEM and TPR techniques for the calcined samples showed the presence of Co3O4 which diminished in the reduced samples and Co0 appeared. The magnetic behavior of the materials was evaluated by magnetization (M) variation with applied magnetic field (H) at different temperatures. Low magnetization is observed in the calcined samples while high values are ttained in the reduced samples, due to the presence of metallic Co. Fil: Pierella, Liliana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; Argentina Fil: Saux, Clara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; Argentina Fil: Bertorello, Hector Raul. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina Fil: Bercoff, Paula Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina Fil: Botta, Pablo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Universidad de Santiago de Compostela; España Fil: Rivas, Jose. Universidad de Santiago de Compostela; España

Magnetic interactions in hexaferrite samples of Ba 1 - x La x + δ Fe 12 - x Co x O 19 composition were studied. The precursor powders—barium carbonate ( BaCO 3 ) , lanthanum oxide (La 2 O 3 ), hematite (Fe 2 O 3 ) and cobalt acetate—were milled for 100 h in air atmosphere and heat-treated for 1 h at 1000 ∘ C . The structural characterization was performed by X-ray diffraction. The FORC distributions show a single peak at high switching fields, indicating that the substituted systems are formed by weakly interacting particles. La excess induces the decoupling of the particles.

In mammalian cells, active sodium transport and its derived functions (e.g., plasma membrane potential) are dictated by the activity of the Na + ,K + -ATPase (NK), whose regulation is essential for maintaining cell volume and composition, as well as other vital cell functions. Here we report the existence of a salt-inducible kinase-1 (SIK1) that associates constitutively with the NK regulatory complex and is responsible for increases in its catalytic activity following small elevations in intracellular sodium concentrations. Increases in intracellular sodium are paralleled by elevations in intracellular calcium through the reversible Na + /Ca 2+ exchanger, leading to the activation of SIK1 (Thr-322 phosphorylation) by a calcium calmodulin-dependent kinase. Activation of SIK1 results in the dephosphorylation of the NK α-subunit and an increase in its catalytic activity. A protein phosphatase 2A/phosphatase methylesterase-1 (PME-1) complex, which constitutively associates with the NK α-subunit, is activated by SIK1 through phosphorylation of PME-1 and its dissociation from the complex. These observations illustrate the existence of a distinct intracellular signaling network, with SIK1 at its core, which is triggered by a monovalent cation (Na + ) and links sodium permeability to its active transport.

Structural and magnetic properties of melt-spun Nd4.5Fe72Co3Cr2Al1B17.5 ribbons were studied by means of differential scanning calorimetry, Mossbauer effect spectroscopy, X-ray diffraction and first-order reversal curve distributions. The presence of a solid solution (Fe, Co) in ribbons annealed at 6851C for 10 min was detected from Mossbauer spectra. Correlations between the observed structural changes at higher annealing temperatures and modifications in the interaction fields of precipitated phases are discussed. r 2007 Elsevier B.V. All rights reserved.

We study the magnetization reversal of a two-particle system with partial exchange coupling. We assume that the particles are discs and that the exchange coupling occurs through one of their plane faces extending up to 5 l w into each particle ( l w =( A / K ) 1/2 ). The easy axis of particle 1 coincides with the direction of the applied magnetic field H and the one corresponding to particle 2 is such that both easy axis are parallel to the contact face. We assume that the spins reorientation across the contact plane is similar to that of a Bloch wall. We write the free energy E of the system in terms of the fraction β of volume affected by exchange coupling, taking into account the anisotropy and exchange energies due to the spin reorientation and to the fraction (1- β ) of non-interacting particles’ volume. For a given volume V the fraction β can be varied by sliding one particle with respect to the other, changing only the contact area. We calculate the ratio E / KV as function of H considering the easy axis of particle 2 at different angles with respect to the easy axis of particle 1. We determine magnetic moments switching paths together with the energy barrier Δ E for switching. We find a general expression of the form Δ E / KV =(1− H / H 0 ) z , with H 0 = H 0 ( β , ω ) and z = z 0 + α ( ω ) β , being z 0 and H 0 (0, ω ) equal to the values for non-interacting particles. We discuss the switching behavior as a function of ω and H .

We have previously reported that dopamine increased active Na+ transport in rat lungs by upregulating the alveolar epithelial Na,K-ATPase. Here we tested whether alveolar epithelial cells produce dopamine and whether increasing endogenous dopamine production by feeding rats a 4% tyrosine diet (TSD) would increase lung liquid clearance. Alveolar Type II cells express the enzyme aromatic-L-amino acid decarboxylase (AADC) and, when incubated with the dopamine precursor, 3-hydroxy-L-tyrosine (L-dopa), produce dopamine. Rats fed TSD, a precursor of L-dopa and dopamine, had increased urinary dopamine levels, which were inhibited by benserazide, an inhibitor of AADC. Rats fed TSD for 15, 24, and 48 hours had a 26, 46, and 45% increase in lung liquid clearance, respectively, as compared with controls. Also, dopaminergic D1 receptor antagonist--but not dopaminergic D2 receptor antagonist--inhibited the TSD-mediated increase in lung liquid clearance. Alveolar Type II cells isolated from the lungs of rats after they had been fed TSD for 24 hours demonstrated increased protein abundance of Na,K-ATPase alpha1 and beta1 subunits. Basolateral membranes isolated from peripheral lung tissue of tyrosine-fed rats had increased Na,K-ATPase activity and Na,K-ATPase alpha1 subunit. These data provide the first evidence that alveolar epithelial cells produce dopamine and that increasing endogenous dopamine increases lung liquid clearance.

The preparation of ZnFe 2 O 4 from mechanochemically activated reactive mixtures Zn–Fe 3 O 4 is studied. The physicochemical and structural evolution of the system is analyzed by X-ray diffraction, vibrating sample magnetometry, differential thermal analysis and scanning electron microscopy. The activated mixtures reacted towards the formation of ZnFe 2 O 4 at lower temperatures than the non-activated ones. In addition, thermal treatments as a function of time revealed a non-expected magnetic behavior of some mixtures. In order to interpret this observation, a qualitative diffusional reaction model is proposed.

The balance and cross-talk between natruretic and antinatruretic hormone receptors plays a critical role in the regulation of renal Na+ homeostasis, which is a major determinant of blood pressure. Dopamine and angiotensin II have antagonistic effects on renal Na+ and water excretion, which involves regulation of the Na+,K+-ATPase activity. Herein we demonstrate that angiotensin II (Ang II) stimulation of AT1 receptors in proximal tubule cells induces the recruitment of Na+,K+-ATPase molecules to the plasmalemma, in a process mediated by protein kinase Cβ and interaction of the Na+,K+-ATPase with adaptor protein 1. Ang II stimulation led to phosphorylation of the α subunit Ser-11 and Ser-18 residues, and substitution of these amino acids with alanine residues completely abolished the Ang II-induced stimulation of Na+,K+-ATPase-mediated Rb+ transport. Thus, for Ang II-dependent stimulation of Na+,K+-ATPase activity, phosphorylation of these serine residues is essential and may constitute a triggering signal for recruitment of Na+,K+-ATPase molecules to the plasma membrane. When cells were treated simultaneously with saturating concentrations of dopamine and Ang II, either activation or inhibition of the Na+,K+-ATPase activity was produced dependent on the intracellular Na+ concentration, which was varied in a very narrow physiological range (9–19 mm). A small increase in intracellular Na+ concentrations induces the recruitment of D1 receptors to the plasma membrane and a reduction in plasma membrane AT1 receptors. Thus, one or more proteins may act as an intracellular Na+ concentration sensor and play a major regulatory role on the effect of hormones that regulate proximal tubule Na+ reabsorption.

Insulin secretion is controlled by the β cell′s metabolic state, and the ability of the secretory granules to undergo exocytosis increases during glucose stimulation in a membrane potential-independent fashion. Here, we demonstrate that exocytosis of insulin-containing secretory granules depends on phosphatidylinositol 4-kinase (PI 4-kinase) activity and that inhibition of this enzyme suppresses glucose-stimulated insulin secretion. Intracellular application of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P 2 ] stimulated exocytosis by promoting the priming of secretory granules for release and increasing the number of granules residing in a readily releasable pool. Reducing the cytoplasmic ADP concentration in a way mimicking the effects of glucose stimulation activated PI 4-kinase and increased exocytosis whereas changes of the ATP concentration in the physiological range had little effect. The PI(4,5)P 2 -binding protein Ca 2+ -dependent activator protein for secretion (CAPS) is present in β cells, and neutralization of the protein abolished both Ca 2+ - and PI(4,5)P 2 -induced exocytosis. We conclude that ADP-induced changes in PI 4-kinase activity, via generation of PI(4,5)P 2 , represents a metabolic sensor in the β cell by virtue of its capacity to regulate the release competence of the secretory granules.

The present study demonstrates that stimulation of hormonal receptors of proximal tubule cells with the serotonin-agonist 8-hydroxy-2-(di-n-propylamino) tetraline (8-OH-DPAT) induces an augmentation of Na+,K+-ATPase activity that results from the recruitment of enzyme molecules to the plasmalemma. Cells expressing the rodent wild-type Na+,K+-ATPase α-subunit had the same basal Na+,K+-ATPase activity as cells expressing the α-subunit S11A or S18A mutants, but stimulation of Na+,K+-ATPase activity was completely abolished in either mutant. 8-OH-DPAT treatment of OK cells led to PKCβ-dependent phosphorylation of the α-subunit Ser-11 and Ser-18 residues, and determination of enzyme activity with the S11A and S18A mutants indicated that both residues are essential for the agonist-dependent stimulation of Na+,K+-ATPase activity. When cells were treated with both dopamine and 8-OH-DPAT, an activation of Na+,K+-ATPase was observed at basal intracellular sodium concentration (∼9 mM), and this activation was gradually reduced and became a significant inhibition as the concentration of intracellular sodium gradually increased from 9 to 19 mM. Thus, besides the antagonistic effects of dopamine and 8-OH-DPAT, intracellular sodium modulates whether an activation or an inhibition of Na+,K+-ATPase is produced. British Journal of Pharmacology (2002) 137, 1380–1386. doi:10.1038/sj.bjp.0704962

The main objective of this study was to develop and test the applicability of a sensitive, accurate, and precise liquid chromatographic (LC) method for evaluating the stability characteristics of a new bisisoxazolylnaphthoquinone, 2-(3,5-dimethyl-4-isoxazolylamino)-N-(3,5-dimethyl-4-isoxazolyl)-1,4-naphthoquinone-4-imine compound 1. The method was shown to be selective and stability-indicating. Isocratic elution with a mobile phase of methanol–water (75 + 25, v/v) on a reversed-phase column with UV detection at ambient temperature completely resolved compound 1 from its degradation products. The LC system was calibrated by plotting peak responses versus known concentrations of a reference standard by using an internal standardization procedure. Complete elution occurred after 12 min with a peak symmetry factor of 0.95 for the drug peak. The kinetic degradation of compound 1 was studied over a pH range of 0.88–14.00 to determine the kinetic parameters involved in its decomposition path in aqueous solution.

We tested the hypothesis that the level of intracellular sodium modulates the hormonal regulation of the Na(+),K(+)-ATPase activity in proximal tubule cells. By using digital imaging fluorescence microscopy of a sodium-sensitive dye, we determined that the sodium ionophore monensin induced a dose-specific increase of intracellular sodium. A correspondence between the elevation of intracellular sodium and the level of dopamine-induced inhibition of Na(+),K(+)-ATPase activity was determined. At basal intracellular sodium concentration, stimulation of cellular protein kinase C by phorbol 12-myristate 13-acetate (PMA) promoted a significant increase in Na(+),K(+)-ATPase activity; however, this activation was gradually reduced as the concentration of intracellular sodium was increased to become a significant inhibition at concentrations of intracellular sodium higher than 16 mm. Under these conditions, PMA and dopamine share the same signaling pathway to inhibit the Na(+),K(+)-ATPase. The effects of PMA and dopamine on the Na(+),K(+)-ATPase activity and the modulation of these effects by different intracellular sodium concentrations were not modified when extracellular and intracellular calcium were almost eliminated. These results suggest that the level of intracellular sodium modulates whether hormones stimulate, inhibit, or have no effect on the Na(+),K(+)-ATPase activity leading to a tight control of sodium reabsorption.

The solid state reaction between Al and Fe3O4 (magnetite) using mechanochemical activation of powder mixtures under Ar atmosphere is studied. The phase evolution during the reaction is analyzed by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), differential thermal analysis (DTA) and scanning electron microscopy (SEM). At 37 minutes of high-energy ball-milling the disappearance of reactive phases and the production of α-Fe, FeAl2O4 and α-Al2O3 is observed, together with significant changes in the magnetic behavior of the system. The composition and properties of samples heated up to 1200°C are also investigated. The behavior of the saturation magnetization M s is interpreted on the basis of the formation of a variable composition spinel phase Fe [Al x Fe2−x ] O4 with 0 ≤ x ≤ 2 and a canting effect due to the presence of Al3+ ions in the spinel structure.

Essential hypertension is associated with alterations of sodium homeostasis, which promote abnormal accumulation of water in the intravascular compartment leading to blood pressure elevations. Salt-inducible kinase 1 (SIK1) belongs to the AMPK family and a single nucleotide polymorphism within the human SIK1 gene is associated with hypertension [lower SIK1 activity is associated with higher blood pressure (HBP)]. SIK1 network mediates sodium-dependent signals that modulate the activity of the Na+,K+-ATPase. We aimed to study the role of SIK1 in cardiovascular and renal homeostasis using SIK1 knockout (KO) mice. No differences in BP were observed between sik1-/- and sik1+/+ mice under 0.3% NaCl diet; however, the sik1-/- mice challenged with an acute or chronic 8% NaCl diet showed increased SBP. We found that under an 8% NaCl diet, Na+, K+ and Cl- excretion was significantly lower in sik1-/- mice compared with wild type mice, despite similar plasma aldosterone levels. The impaired ability of sik1-/- to eli...

As part of their preformulation evaluation, four in vitro protozoocidal 3,4-dimethyl-5-isoxazolylnaphthoquinones (ANQ-1–4) were investigated by differential scanning calorimetry (DSC), simultaneous differential thermal analysis–thermogravimetry–derivative thermogravimetry (DTA–TG–DTG), and Fourier transform infrared spectroscopy (FTIR). X-ray powder diffractometry (XRPD), thermomicroscopy and polarized light microscopy were used as an aid to interpret the thermoanalytical curves. The study demonstrated that the compounds are crystalline solids, unaffected by oxygen, safely manipulated at room temperature (RT) and also at higher temperatures as solids; however, all decompose exothermically at about their mp. Polycrystalline mixtures or undesirable solvates were not detected. All the compounds are insoluble in water and n-hexane and slightly soluble in ethanol, indicating that all are candidates to improve their solubilities in order to avoid formulation problems.

A new synthetic gel was obtained by bulk polymerization of castor oil, acrylic acid and acrylamide. This paper describes the ability of this gel to uptake heavy metals and nitrate ions from aqueous solutions as demonstrated in our laboratory. Determinations, before and after batch experiments, were carried out using atomic absorption and UV spectroscopy. These results showed that Al+3, Fe+3 and Pb+2 ions were effectively adsorbed.

The complexation of 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (I) with a highly soluble cyclodextrin, hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was studied in aqueous media by solubility methods. I is an antibacterial and trypanocidal agent that is undergoing preclinical testing. Unfortunately, I exhibits low water solubility, and it is therefore difficult to prepare the solutions for biological tests. I inclusion took place with 1:1 stoichiometry. The stability constants of the I complexes calculated from the slope and the intercept of the phase solubility diagrams are larger in the less ionized form, whereas greater overall solubility is obtained in basic media.

The structure and magnetic properties of different magnetic compounds are studied. The compounds are produced by first milling 80% Ba hexaferrite and 20% Fe for 40 h (giving severely deformed hexaferrite plus Fe), and for 60 h (giving magnetite plus Ba carbonate). These two precursors are annealed at 850, 900 and 1000°C in air and characterized by their structure and magnetic properties. When the precursor consists of deformed hexaferrite and Fe, the thermal treatment promotes the elimination of defects in the hexaferrite and the oxidation of Fe to hematite and some magnetite. In the other case, that is, when the precursor is magnetite and Ba carbonate the annealing produces the re-transformation to the original hexaferrite and the excess of magnetite transforms to hematite. In this situation the annealing at 1000°C produces a compound with a coercivity of 4.4 kOe and a maximum magnetization at 15 kOe of over 51 emu/g, values which are comparable to the ones in the literature for this material considering that the fraction of hexaferrite in the samples is 80%.

Water, ethanol and n -hexane solubility and pH–solubility behavior of a homologous series of isoxazolyl–naphthoquinone derivatives, which exhibit important biological activity, were studied. Their p K a values were determined spectrophotometrically as well as from their pH–solubility profiles. Also, the molar aqueous solubility of these compounds was estimated with the equations developed by Yalkowsky and Valvani using the data of their melting points and octanol/water partition coefficients.

We previously reported that lung edema clearance was stimulated by dopamine (DA). The purpose of this study was to determine whether the DA-mediated stimulation of edema clearance occurs via an adrenergic or dopaminergic regulation of alveolar epithelial Na, K-ATPase. When isolated perfused rat lungs were coinstilled with DA and SCH 23390 (a specific D(1) receptor antagonist), there was a dose-dependent attenuation of the stimulatory effects of DA. Coinstillation with S-sulpiride (a specific D(2) receptor antagonist) or propranolol (a beta-adrenergic antagonist) did not alter DA-stimulated clearance. Similarly, the specific dopaminergic D(1) agonist fenoldopam increased lung edema clearance, but quinpirole (a specific dopaminergic D(2) agonist) did not. (125)I-SCH 23982 binding studies suggested that D(1) receptors are expressed on alveolar type II (ATII) cells with an apparent dissociation constant (K(d)) of 4.4 nM and binding maximum (Bmax) 9.8 pmol/mg. Consistent with these results, the D(1) receptor messenger RNA (mRNA) and protein were detected in ATII cells by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. These data demonstrate a novel mechanism involving the activation of dopaminergic D(1) receptors which mediates DA-stimulated edema removal from rat lungs.

Dopamine (DA) inhibits rodent proximal tubule Na+,K+-ATPase via stimulation of protein kinase C (PKC). However, direct stimulation of PKC by phorbol 12-myristate 13-acetate (PMA) results in increased Na+,K+-ATPase. LY333531, a specific inhibitor of the PKC-beta isoform, prevents PMA-dependent activation of Na+,K+-ATPase, but has no effect on DA inhibition of this activity. A similar result was obtained with a PKC-beta inhibitor peptide. Concentrations of staurosporine, that inhibits PKC-zeta, prevent DA-dependent inhibition of Na+,K+-ATPase and a similar effect was obtained with a PKC-zeta inhibitor peptide. Thus, PMA-dependent stimulation of Na+,K+-ATPase is mediated by activation of PKC-beta, whereas inhibition by DA requires activation of PKC-zeta.

The lipophilic character of a series of new isoxazolyl-naphthoquinones has been studied. Partition chromatography procedures (RP-HPLC and RP-TLC) were developed for determining the log Po-w(n-octanol/water partition coefficient) values. The experimental values from these methods were validated by comparison with those obtained from the conventional shake flask method, except with the more lipophilic because they have poor water solubility. Also, the log Po-w was calculated using a CLOGP computer programme.

A Ba-hexaferrite/Fe composite is synthesized using a high-energy ball mill. Changes in the crystalline structure and magnetic properties are studied with the aid of X-ray diffraction and magnetization measurements. The product after an 80 h mill is magnetite (Fe 3 O 4 ) and barium carbonate (BaCO 3 ). After heating up to 1300 K in air and Ar atmospheres it is found that in the former case the product is phase M (BaFe 12 O 19 ) and hematite (α-Fe 2 O 3 ) with improved magnetic properties while in the second, BaFe 12 O 19 and Fe 3 O 4 are obtained. This is a magnetic composite material having both dipolar and exchange couplings. The coercivity observed is explained in terms of the modified Brown's equation for inverse domain nucleation fields.

1. The aim of this study was to investigate the mechanism of control of Na+,K+-ATPase activity by the cAMP-protein kinase A (PKA) pathway in rat proximal convoluted tubules. For this purpose, we studied the in vitro action of exogenous cAMP (10-3 M dibutyryl-cAMP (db-cAMP) or 8-bromo-cAMP) and endogenous cAMP (direct activation of adenylyl cyclases by 10-5 M forskolin) on Na+,K+-ATPase activity and membrane trafficking. 2. PKA activation stimulated both the cation transport and hydrolytic activity of Na+,K+-ATPase by about 40%. Transport activity stimulation was specific to the PKA signalling pathway since (1) db-cAMP stimulated the ouabain-sensitive 86Rb+ uptake in a time- and dose-dependent fashion; (2) this effect was abolished by addition of H-89 or Rp-cAMPS, two structurally different PKA inhibitors; and (3) this stimulation was not affected by inhibition of protein kinase C (PKC) by GF109203X. The stimulatory effect of db-cAMP on the hydrolytic activity of Na+,K+-ATPase was accounted for by an increased maximal ATPase rate (Vmax) without alteration of the efficiency of the pump, suggesting that cAMP-PKA pathway was implicated in membrane redistribution control. 3. To test this hypothesis, we used two different approaches: (1) cell surface protein biotinylation and (2) subcellular fractionation. Both approaches confirmed that the cAMP-PKA pathway was implicated in membrane trafficking regulation. The stimulation of Na+,K+-ATPase activity by db-cAMP was associated with an increase (+40%) in Na+, K+-ATPase units expressed at the cell surface which was assessed by Western blotting after streptavidin precipitation of biotinylated cell surface proteins. Subcellular fractionation confirmed the increased expression in pump units at the cell surface which was accompanied by a decrease (-30%) in pump units located in the subcellular fraction corresponding to early endosomes. 4. In conclusion, PKA stimulates Na+,K+-ATPase activity, at least in part, by increasing the number of Na+-K+ pumps in the plasma membrane in proximal convoluted tubule cells.

The goal of this study was to determine the kinetic parameters involved in the decomposition of 2-(5-methyl-4-isoxazolylamino)-N-(5-methyl-4-isoxazolyl)-1,4-naphthoquinone-4-imine (1) in aqueous solution and to identify the main degradation products. An isocratic HPLC assay was used to study the degradation rate of 1. The products of hydrolysis were identified by comparison of their retention times with those of authentic samples. The amount of 1 and the two degradation products resulting from storage of 1 in various buffer solutions was followed in function of time by a reversed-phase HPLC stability-indicating method. The observed degradation rates followed pseudo-first-order kinetics at constant pH, temperature and ionic strength. The log k–pH-profile was constructed at 35°C from the first-order rate constants obtained from studies at pH values ranging from 0.88 to 10.80 (μ=0.5 M). Hydrolysis in the acidic and alkaline media resulted in the formation of two degradation products in each case. The pH-rate profile of 1 in buffer solution was adequately described using a four-term rate equation. The obtained pH-rate profile indicated specific acid–base catalysis with a region of maximum stability between pH 6.40 and 7.40 which can be adequate for formulations of 1.

The synthesis of a new cross-linked structure, with sucrose and diepoxide monomers, possessing the properties of a highly swellable hydrogel polymer is reported. Characterization studies of its structure and water effects were carried out in dried and hydrated samples by CP-MAS 13C n.m.r., by wide-band 1H and 2H n.m.r. and by differential thermal analysis. The results indicate that the sample is completely amorphous and disordered, that methyl groups are present and that there is strong water structuring due to hydrogen bonding, with an absence of free water at low levels of hydration. Two processes are manifest in the temperature dependence of the 2H line width.

Dopamine (DA) inhibition of Na+,K+-ATPase in proximal tubule cells is associated with increased endocytosis of its α and β subunits into early and late endosomes via a clathrin vesicle-dependent pathway. In this report we evaluated intracellular signals that could trigger this mechanism, specifically the role of phosphatidylinositol 3-kinase (PI 3-K), the activation of which initiates vesicular trafficking and targeting of proteins to specific cell compartments. DA stimulated PI 3-K activity in a time- and dose-dependent manner, and this effect was markedly blunted by wortmannin and LY 294002. Endocytosis of the Na+,K+-ATPase α subunit in response to DA was also inhibited in dose-dependent manner by wortmannin and LY 294002. Activation of PI 3-K generally occurs by association with tyrosine kinase receptors. However, in this study immunoprecipitation with a phosphotyrosine antibody did not reveal PI 3-K activity. DA-stimulated endocytosis of Na+,K+-ATPase α subunits required protein kinase C, and the ability of DA to stimulate PI 3-K was blocked by specific protein kinase C inhibitors. Activation of PI 3-K is mediated via the D1receptor subtype and the sequential activation of phospholipase A2, arachidonic acid, and protein kinase C. The results indicate a key role for activation of PI 3-K in the endocytic sequence that leads to internalization of Na+,K+-ATPase α subunits in response to DA, and suggest a mechanism for the participation of protein kinase C in this process.

The effects of the hydroxypropyl- β -cyclodextrin (HPCD) on the solubility of 2-hydroxy- N -(5-methyl-3-isoxazolyl)-1,4-naphthoquinone-4-imine ( I ) were investigated. I is an experimental drug for the treatment of cancer which exhibits low water solubility and it is therefore difficult to prepare the solutions for biological tests. The presence of an ionizable hydroxyl moiety (p K a =5.80) increases the solubility via pH adjustment, but only a solubility of 0.124 mg/ml was obtained at pH 8.00. I was found to form inclusion complexes in either its neutral or its anionic form with HPCD. Although the stability constant of the I complex is larger in the neutral form, a greater overall solubility is obtained when I is in its ionized form. A 270-fold solubility enhancement is possible by using a combined approach of pH adjustment and complexation with HPCD.

Inositol hexakisphosphate (InsP 6 ), the dominant inositol phosphate in insulin-secreting pancreatic β cells, inhibited the serine-threonine protein phosphatases type 1, type 2A, and type 3 in a concentration-dependent manner. The activity of voltage-gated L-type calcium channels is increased in cells treated with inhibitors of serine-threonine protein phosphatases. Thus, the increased calcium channel activity obtained in the presence of InsP 6 might result from the inhibition of phosphatase activity. Glucose elicited a transient increase in InsP 6 concentration, which indicates that this inositol polyphosphate may modulate calcium influx over the plasma membrane and serve as a signal in the pancreatic β cell stimulus-secretion coupling.

In this paper, a series of different adsorbents for pseudobiospecific ligand affinity chromatography is presented. They were obtained using ligands as histidine, Cu 2+ - or Zn 2+4 -chelating iminodiacetic acid and Cibacron Bhue F3GA dye, attached to poly(butadiene-hydroxyethylmethacrylate) (PB-HEMA) matrix. The histidine and metal-iota-chelating iminodiacetic acid were attached on matrix through epichlorohydrin (ECH) or 1,4-butanediol diglycidyl ether (BDGE) as spacers and activators, while dye was directly bound onto the matrix.

Graft copolymerization of sucrose acrylate (SA) onto 55 μm films of poly(vinyl chloride) (PVC) was investigated with benzophenone or 2,2′-azoisobutironitrile as the initiator. The grafting reactions were carried out in a closed cell containing the films to be treated with a solution of the sensitizer and the monomer. In this system, ultraviolet light through a quartz window initiated the reaction by exciting the initiator used. The grafting took place on a PVC surface layer, from the solution. The homopolymer formed during copolymerization was removed by washing. The percentage of grafting was determined by gravimetric measurements and by dye adsorption (crystal violet), and the characterization of PVC(g)SA was carried out by the use of infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis. The weathering behavior of PVC(g)SA was studied with microorganisms in a growing medium, and the degradation was monitored by the weight loss of the films, FTIR, and SEM. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1195–1201, 1997

The tautomeric binary system consisting of N-(3,4-dimethyl-5-isoxazolyl)-4-amino-1,2-naphthoquinone (1),m.p. 156‡C, and 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinon-4-imine (2),m.p. 218‡C, was studied by DTA-TG-DTG and IR spectrometry. Crystals of 1, left in contact with their mother liquor during 4 months, exhibited thermal behaviour similar to that of physical mixtures of 1 and 2, which reveal the presence of a eutectic at about 146‡C.

The application of the second-derivative UV spectrophotometry for determining the stability of 3-bromo-N-bromo-N-(3,4-dimethyl-5-isoxazolyl-4-amine)-1,2-naphthoquinone in ethanolic solutions is described. The validity of this method was evaluated using synthetic mixtures of the intact drug and its degradation products and by statistical analysis of the calibration data. In order to verify the usefulness of this method for stability studies, recovery experiments by the standard addition method were also carried out.

Dopamine (DA) produces a natriuresis attributed in part to inhibition of Na,K-ATPase activity (NKA) in the proximal tubule (PCT), and impairment in this inhibition has been linked to several forms of hypertension in animals. Here we examined whether the intracellular signaling mechanisms involved are the same in the early and late phases of this phenomenon. DA (1 microM) inhibited NKA similarly after 15 min (by 38%) or 180 min (by 36%) incubation, taken to represent short-term (ST) and sustained (Sd) pump regulation, respectively. Calphostin C, a specific inhibitor of protein kinase C (PKC), completely blocked the ST action of DA on NKA, whereas IP20, a specific inhibitor of protein kinase (PKA), had no effect. In contrast, IP20 completely abolished the Sd (180 min) inhibition by DA, whereas calphostin C had only a partial or variable effect. The DA-1 agonist fenoldopam (which does not activate PKC but increases cAMP) alone failed to inhibit the pump at 180 min (as it does also in the short-term in PCT), suggesting that ST inhibition is required for the Sd effect to occur. Furthermore, PTH1-34, a known ST inhibitor of NKA suppressed the pump at 180 min (by 46%), but unlike in the short-term, this effect was completely prevented by IP20. In contrast, PTH3-34, which does not stimulate adenylyl cyclase or activate PKA, caused only a small (19%) and variable Sd inhibition. In conclusion, short-term inhibition of the PCT pump by dopamine is mediated via PKC, whereas the sustained inhibition requires the PKA pathway in addition to the ongoing PKC-mediated effect.

New pseudoaffinity chromatography supports were prepared and characterized from poly(sucrose acrylate) crosslinked with MDI or TDI and Cibacron Blue dye as ligand. Blue gels were useful in the retention of albumin and the results are reported.

The property of albumin to bind long-chain fatty acids was exploited for the development of adsorbents containing them as ligands to isolate that protein. The synthesis of gels containing oleic or ricinoleic acids bonded to a synthetic matrix and the capacity to retain albumin are presented. The probable retention of other proteins (gelatin and lysozyme) was also tested.

An RP-HPLC procedure was developed for determining the lipophilicity of a series of isoxazolyl-naphthoquinones which possess antibacterial, trypanosidal and antineoplasic activity. The experimental results were compared with theoretical log P values, and it was found that there was a good relationship between the two methods, except for very lipophilic compounds.

Synthetic crosslinked polymers from oligomers of butadiene-co-acrylic acid (Mω 5000) or oligomers of butadiene (Mω 6000) and acrylic acids were obtained after grafting reactions using varying reactant ratios. Characterization of the new crosslinked polymers were carried out by use of FTIR, H-NMR, and 13 C-NMR in the solid state and also with the swollen products in D 2 O, DMF D7, or DMSO D6. Determinations of swelling in distilled water for the different synthesized hydrogels showed increase in the V/Vo ratios as the concentrations of anions (carboxylate) became higher. These values were sensitive to different pH values and changes in the concentrations of electrolytes. Different behavior was observed for the polymers obtained from mass and from synthesis in benzene. SEM analysis of the surfaces of the polymers obtained in mass showed a fibrous structure (with lower contents of carboxylic groups, and more swellable and with greater capacity to retain albumin). A porous surface was observed for products obtained in benzene (with higher content of carboxyl groups and capacity to retain cations such as copper and malachite green).

Synthetic crosslinked polymers were obtained by reacting oligomers of polybutadiene (av. mol. wt. ∼6000) with acrylamide and acrylic acid. Characterization of these new block-crosslinked polymers was carried out by FTIR, 1 H-NMR, 13 C-NMR, SEM analyses, DTA, and DTG. The polymers were washed with benzene, ethanol, water, and acetone and then dried at high vacuum. Determinations of the swelling ratio Vs/Vo for the poly (BuAAAm)H, acid form, and poly (BuAAAm)Na, sodium form, were carried out in distilled water, at different pH values and concentrations of electrolytes. Kinetic studies with diffusion of solvents were related to the network structures of the poly (BuAAAm) in acid and sodium forms.