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Background: Ocular manifestations of the dengue fever virus include bilateral panuveitis that can occur after the acute systemic infection has resolved. In most reported cases, the inflammation resolves with topical or systemic steroid therapy. We report a case of chronic, refractory bilateral panuveitis and uveitic glaucoma that began during the acute phase of the systemic infection and required treatment with oral steroids, multiple steroid-sparing agents, and surgical therapy for glaucoma., Findings: A 22-year-old male with acute systemic dengue fever presented with bilateral pain and decreased vision. Clinical examination revealed bilateral panuveitis with elevated intraocular pressures. Management required oral steroids, mycophenolate mofetil, cyclosporine, and bilateral glaucoma valve implantation., Conclusion: This case highlights the fact that dengue-associated panuveitis can begin in the acute stage of systemic infection and persist long after convalescence with progression to chronic bilateral panuveitis and uveitic glaucoma. Dengue-associated chronic panuveitis with uveitic glaucoma may be effectively managed with a combination of steroid-sparing oral immunosuppression and glaucoma surgery. This is, to our knowledge, the first case of bilateral refractory dengue-associated panuveitis from the Caribbean treated with combination steroid-sparing oral immunosuppression and bilateral glaucoma valve implantation.

The effects of lipids on membrane proteins are likely to be complex and unique for each membrane protein. Here we studied different detergent/phosphatidylcholine reconstitution media and tested their effects on plasma membrane Ca(2+) pump (PMCA). We found that Ca(2+)-ATPase activity shows a biphasic behavior with respect to the detergent/phosphatidylcholine ratio. Moreover, the maximal Ca(2+)-ATPase activity largely depends on the length and the unsaturation degree of the hydrocarbon chain. Using static light scattering and fluorescence correlation spectroscopy, we monitored the changes in hydrodynamic radius of detergent/phosphatidylcholine particles during the micelle-vesicle transition. We found that, when PMCA is reconstituted in mixed micelles, neutral phospholipids increase the enzyme turnover. The biophysical changes associated with the transition from mixed micelles to bicelles increase the time of residence of the phosphorylated intermediate (EP), decreasing the enzyme turnover. Molecular dynamics simulations analysis of the interactions between PMCA and the phospholipid bilayer in which it is embedded show that in the 1,2-dioleoyl-sn-glycero-3-phosphocholine bilayer, charged residues of the protein are trapped in the hydrophobic core. Conversely, in the 1,2-dimyristoyl-sn-glycero-3-phosphocholine bilayer, the overall hydrophobic-hydrophilic requirements of the protein surface are fulfilled the best, reducing the thermodynamic cost of exposing charged residues to the hydrophobic core. The apparent mismatch produced by a 1,2-dioleoyl-sn-glycero-3-phosphocholine thicker bilayer could be a structural foundation to explain its functional effect on PMCA., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)

A new class of guest-induced, bi-radical self-assembled organic capsules is reported. They are formed by the inclusion of a tetramethylammonium (TMA) cation between two monomers of the stable trityl radical OX63. OX63 is extensively used in dissolution dynamic nuclear polarization (DNP) where it leads to NMR sensitivity enhancements of several orders of magnitude. The supramolecular properties of OX63 have a strong impact on its DNP properties. An especially relevant case is the polarization of choline-containing metabolites, where complex formation between choline and OX63 results in faster relaxation.

A major challenge for realizing quantum computation is finding suitable systems to embody quantum bits (qubits) and quantum gates (qugates) in a robust and scalable architecture. An emerging bottom-up approach uses the electronic spins of lanthanides. Universal qugates may then be engineered by arranging in a molecule two interacting and different lanthanide ions. Preparing heterometallic lanthanide species is, however, extremely challenging. We have discovered a method to obtain [LnLn'] complexes with the appropriate requirements. Compound [CeEr] is deemed to represent an ideal situation. Both ions have a doubly degenerate magnetic ground state and can be addressed individually. Their isotopes have mainly zero nuclear spin, which enhances the electronic spin coherence. The analogues [Ce2], [Er2], [CeY], and [LaEr] have also been prepared to assist in showing that [CeEr] meets the qugate requirements, as revealed through magnetic susceptibility, specific heat, and EPR. Molecules could now be used for quantum information processing.

A novel Dy-complex formulated as {[Dy2Ba(α-C4H3OCOO)8·(H2O)4]·2H2O}n, {Dy2Ba(α-fur)8}n, has been synthesized, structurally characterized, and magnetically and thermally investigated as a function of field and temperature, down to 85 mK. The α-furoate ligands consolidate 1D zig-zag chains formed by Dy2 dimers separated by Ba ions. Ab initio calculations were used to determine the easy anisotropy axis direction, the gyromagnetic tensor components and the energy levels of each Dy. The heat capacity and susceptibility measurements allowed us to conclude that intradimer and interdimer interactions are ferromagnetic and of the same order, J'/k(B) ≈ J''/k(B) = +0.55 K. In the absence of an applied magnetic field, the dynamic relaxation of the magnetization occurs through the fast (τ(T) ~ 10(-5) s) spin-reversal of each of the individual Dys through a quantum tunneling (QT) process. A long-range 3D ordered state is achieved at T(N) = 0.25 K, in which the ferromagnetically coupled zig-zag chains (J'/k(B) ≈ J''/k(B) = +0.528(1) K) running along the c-axis are antiferromagnetically coupled to the adjacent chains (J'''/k(B) = -0.021(1) K). Critical slowing down of the QT time constant is observed when the temperature approaches T(N). Under the application of a magnetic field, the QT relaxation is replaced by an Orbach process (with energy barrier U/k(B) = 68 K and τ0 ~ 10(-9) s at H = 2 kOe) and a very slow (τ(s) ∼ 0.2 s) relaxation process. We propose and demonstrate the proof of concept of a spintronic device, in which two different relaxation rates can be selected, and on/off switched by magnetic field biasing. The dynamical behavior of this compound is compared with another furoate to discuss the effect of competitive interactions.

Transition metal ions with long-lived spin states represent minimum size magnetic bits. Magnetic memory has often been associated with the combination of high spin and strong uniaxial magnetic anisotropy. Yet, slow magnetic relaxation has also been observed in some Kramers ions with dominant easy-plane magnetic anisotropy, albeit only under an external magnetic field. Here we study the spin dynamics of cobalt(II) ions in a model molecular complex. We show, by means of quantitative first-principles calculations, that the slow relaxation in this and other similar systems is a general consequence of time-reversal symmetry that hinders direct spin-phonon processes regardless of the sign of the magnetic anisotropy. Its magnetic field dependence is a subtle manifestation of electronuclear spin entanglement, which opens relaxation channels that would otherwise be forbidden but, at the same time, masks the relaxation phenomenon at zero field. These results provide a promising strategy to synthesize atom-size magnetic memories.

The insertion of the single-molecule magnet (SMM) [Mn(III)(salen)(H2O)]2(2+) (salen(2-) = N,N'-ethylenebis-(salicylideneiminate)) into a ferromagnetic bimetallic oxalate network affords the hybrid compound [Mn(III)(salen)(H2O)]2[Mn(II)Cr(III)(ox)3]2⋅(CH3OH)⋅(CH3CN)2 (1). This cationic Mn2 cluster templates the growth of crystals formed by an unusual achiral 3D oxalate network. The magnetic properties of this hybrid magnet are compared with those of the analogous compounds [Mn(III)(salen)(H2O)]2[Zn(II)Cr(III)(ox)3]2⋅(CH3OH)⋅(CH3CN)2 (2) and [In(III)(sal2-trien)][Mn(II)Cr(III)(ox)3]⋅(H2O)0.25⋅(CH3OH)0.25⋅(CH3CN)0.25 (3), which are used as reference compounds. In 2 it has been shown that the magnetic isolation of the Mn2 clusters provided by their insertion into a paramagnetic oxalate network of Cr(III) affords a SMM behavior, albeit with blocking temperatures well below 500 mK even for frequencies as high as 160 kHz. In 3 the onset of ferromagnetism in the bimetallic Mn(II) Cr(III) network is observed at Tc = 5 K. Finally, in the hybrid compound 1 the interaction between the two magnetic networks leads to the antiparallel arrangement of their respective magnetizations, that is, to a ferrimagnetic phase. This coupling induces also important changes on the magnetic properties of 1 with respect to those of the reference compounds 2 and 3. In particular, compound 1 shows a large magnetization hysteresis below 1 K, which is in sharp contrast with the near-reversible magnetizations that the SMMs and the oxalate ferromagnetic lattice show under the same conditions., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Direct measurements of the linear ac susceptibility and magnetic relaxation of a few Mn12 monolayers deposited on a μ-SQUID sensor are reported. In order to integrate the molecules into the device, DPN has been the technique of choice. It enabled the structuration of the molecules on the most sensitive areas of the sensor without the need for any previous functionalization of the molecule or the substrate, while controlling the number of molecular units deposited on each array. The measurements reveal that their characteristic SMM behaviour is lost, a fact that is attributed to molecular distortions originated by the strong surface tensions arising at the molecular interphases.

We show that the dynamic magnetic susceptibility and the superparamagnetic blocking temperature of an Fe(8) single molecule magnet oscillate as a function of the magnetic field H(x) applied along its hard magnetic axis. These oscillations are associated with quantum interferences, tuned by H(x), between different spin tunneling paths linking two excited magnetic states. The oscillation period is determined by the quantum mixing between the ground S=10 and excited multiplets. These experiments enable us to quantify such mixing. We find that the weight of excited multiplets in the magnetic ground state of Fe(8) amounts to approximately 11.6%.

The synthesis and magnetostructural properties of a new low-dimensional magnetic system based on α-furoate ligands, {[Dy(α-C4H3OCOO)(μ-(α-C4H3OCOO))2(H2O)3]}n, abbreviated {Dy(α-fur)3}n, are reported. X-ray diffraction experiments results evidence the presence of two different Dy coordination environment types differing only in the position of one of the furoate ligands. The crystallographic structure is formed by polymeric chains along the c-axis, each composed of just one Dy type, coupled within the bc-plane with chains of the same Dy type. These planes, each of them containing only one Dy type, are randomly stacked along the a-axis. The magnetic behaviour was studied by magnetization, static and dynamic susceptibility, heat capacity measurements and ab initio simulations. The directions of the easy axes of magnetization, gyromagnetic values and energy level structures of the two Dy types were obtained from ab initio calculations. {Dy(α-fur)3}n exhibits slow magnetic relaxation dynamics below 10 K. The two Dy types with different coordination environments behave as single-ion magnets, with different thermal activation energies of 80.5(6) K and 32.4(5) K, until they reach, upon cooling, a quantum tunneling (QT) regime. Magnetic diluted samples, substituting Dy by Y, {Y(x)Dy(1-x)(α-fur)3}n, were prepared to study the effect of intercluster interactions. Decreasing the Dy interaction by dilution by 90-95% leaves the activation energy unchanged, but shifts the transition to the QT regime to lower temperatures. At T = 2.4 K the tunneling time constant has been shown to decrease weakly with the field in the x = 0 case, and more strongly for x = 0.9. As the external field increases, quantum tunneling is quenched and a new slow relaxation appears that is identified at high fields as caused by a direct relaxation process. As the temperature is decreased, interchain AF coupling becomes effective and gives rise to the occurrence of an antiferromagnetic 3D order transition at T(N) = 0.66 K. From all the evidence, it is concluded that within each bc-plane Dy ions arrange in chains along the c-direction, having weak uncompensated ferromagnetic spin-canted intrachain coupling and antiferromagnetic interchain coupling.

A complete isostructural series of dinuclear asymmetric lanthanide complexes has been synthesized by using the ligand 6-[3-oxo-3-(2-hydroxyphenyl)propionyl]pyridine-2-carboxylic acid (H3L). All complexes have the formula [Ln2(HL)2(H2L)(NO3)(py)(H2O)] (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14), Y (15); py = pyridine). Complexes of La to Yb and Y have been crystallographically characterized to reveal that the two metal ions are encapsulated within two distinct coordination environments of differing size. Whereas one site maintains the coordination number (nine) through the whole series, the other one increases from nine to ten owing to a change in the coordination mode of an NO3(-) ligand. This series offers a unique opportunity to study in detail the lanthanide contraction within complexes of more than one metal. This analysis shows that various representative parameters proportional to this contraction follow a quadratic decay as a function of the number n of f electrons. Slater's model for the atomic radii has been used to extract, from these decays, the shielding constant of 4f electrons. The average of O⋅⋅⋅O distances within the coordination polyhedra shared by both metals and of the Ln⋅⋅⋅Ln separations follow also a quadratic decay, therefore showing that such dependence holds also for parameters that receive the contribution of two lanthanide ions simultaneously. The magnetic behavior has been studied for all nondiamagnetic complexes. It reveals the effect of the spin-orbit coupling and a weak antiferromagnetic interaction between both metals. Photoluminescent studies of all the complexes in the series reveal a single broad emission band in the visible region, which is related to the coordinated ligand. On the other hand, the Nd, Er, and Yb complexes show features in the near-IR region due to metal-based transitions., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Intensive care medicine in Chile is still in its dawn. It has experienced a progressive growth in the last decade, but continues to be weak. Although investments in the discipline have increased fivefold, there is still a severe deficiency of intensive care specialists. This issue will represent a serious problem in the near future. The Ministry of Health gathered an expert committee to study the problem and propose solutions for the future development of the discipline.

Magnetic properties of Au nanoparticles deposited on an archaeal S layer are reported. X-ray magnetic circular dichroism and superconducting quantum interference device magnetometries demonstrate that the particles are strongly paramagnetic, without any indication of magnetic blocking down to 16 mK. The average magnetic moment per particle is M(part)=2.36(7) μ(B). This contribution originates at the particle's Au 5d band, in which an increased number of holes with respect to the bulk value is observed. The magnetic moment per Au atom is 25 times larger than any measured in other Au nanoparticles or any other configurations up to date.

A robust, stable and processable family of mononuclear lanthanoid complexes based on polyoxometalates (POMs) that exhibit single-molecule magnetic behavior is described here. Preyssler polyanions of general formula [LnP(5)W(30)O(110)](12-) (Ln(3+) = Tb, Dy, Ho, Er, Tm, and Yb) have been characterized with static and dynamic magnetic measurements and heat capacity experiments. For the Dy and Ho derivatives, slow relaxation of the magnetization has been found. A simple interpretation of these properties is achieved by using crystal field theory.

The polyoxometalate clusters with formula [Gd(W(5) O(18) )(2) ](9-) and [Gd(P(5) W(30) O(110) )](12-) each carry a single magnetic ion of gadolinium, which is the most widespread element among magnetic refrigerant materials. In an adiabatic demagnetization, the lowest attainable temperature is limited by the presence of magnetic interactions that bring about magnetic order below a critical temperature. We demonstrate that this limitation can be overcome by chemically engineering the molecules in such a way to effectively screen all magnetic interactions, suggesting their use as ultra-low-temperature coolers., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report ac susceptibility and continuous wave and pulsed EPR experiments performed on GdW10 and GdW30 polyoxometalate clusters, in which a Gd3+ ion is coordinated to different polyoxometalate moieties. Despite the isotropic character of gadolinium as a free ion, these molecules show slow magnetic relaxation at very low temperatures, characteristic of single molecule magnets. For T≲200  mK, the spin-lattice relaxation becomes dominated by pure quantum tunneling events, with rates that agree quantitatively with those predicted by the Prokof'ev and Stamp model [Phys. Rev. Lett. 80, 5794 (1998)]. The sign of the magnetic anisotropy, the energy level splittings, and the tunneling rates strongly depend on the molecular structure. We argue that GdW30 molecules are also promising spin qubits with a coherence figure of merit Q(M)≳50.

An extended polypyrazolyl ligand has been used to assemble Mn ions into high spin entities, in the form of one stable molecule composed of two well defined clusters. The slow relaxation of the magnetisation observed is demonstrated to arise from each "half-SMM" composing this molecular cluster pair., (This journal is © The Royal Society of Chemistry 2012)

A very exciting prospect in coordination chemistry is to manipulate spins within magnetic complexes for the realization of quantum logic operations. An introduction to the requirements for a paramagnetic molecule to act as a 2-qubit quantum gate is provided in this tutorial review. We propose synthetic methods aimed at accessing such type of functional molecules, based on ligand design and inorganic synthesis. Two strategies are presented: (i) the first consists in targeting molecules containing a pair of well-defined and weakly coupled paramagnetic metal aggregates, each acting as a carrier of one potential qubit, (ii) the second is the design of dinuclear complexes of anisotropic metal ions, exhibiting dissimilar environments and feeble magnetic coupling. The first systems obtained from this synthetic program are presented here and their properties are discussed.

Lipid-protein interactions play an essential role in the regulation of biological function of integral membrane proteins; however, the underlying molecular mechanisms are not fully understood. Here we explore the modulation by phospholipids of the enzymatic activity of the plasma membrane calcium pump reconstituted in detergent-phospholipid mixed micelles of variable composition. The presence of increasing quantities of phospholipids in the micelles produced a cooperative increase in the ATPase activity of the enzyme. This activation effect was reversible and depended on the phospholipid/detergent ratio and not on the total lipid concentration. Enzyme activation was accompanied by a small structural change at the transmembrane domain reported by 1-aniline-8-naphtalenesulfonate fluorescence. In addition, the composition of the amphipilic environment sensed by the protein was evaluated by measuring the relative affinity of the assayed phospholipid for the transmembrane surface of the protein. The obtained results allow us to postulate a two-stage mechanistic model explaining the modulation of protein activity based on the exchange among non-structural amphiphiles at the hydrophobic transmembrane surface, and a lipid-induced conformational change. The model allowed to obtain a cooperativity coefficient reporting on the efficiency of the transduction step between lipid adsorption and catalytic site activation. This model can be easily applied to other phospholipid/detergent mixtures as well to other membrane proteins. The systematic quantitative evaluation of these systems could contribute to gain insight into the structure-activity relationships between proteins and lipids in biological membranes.

This work describes the usability studies conducted in the development of an experience-sampling methodology (ESM) system running in a mobile device. The goal of the system is to improve the accuracy and ecology in gathering daily self-report data in individuals suffering a chronic pain condition, fibromyalgia. The usability studies showed that the developed software to conduct ESM with mobile devices (smartphones, cell phones) can be successfully used by individuals with fibromyalgia of different ages and with low level of expertise in the use of information and communication technologies. 100% of users completed the tasks successfully, although some have completely illiterate. Also there seems to be a clear difference in the way of interaction obtained in the two studies carried out.

We show that a chemically engineered structural asymmetry in [Tb2] molecular clusters renders the two weakly coupled Tb3+ spin qubits magnetically inequivalent. The magnetic energy level spectrum of these molecules meets then all conditions needed to realize a universal CNOT quantum gate. A proposal to realize a SWAP gate within the same molecule is also discussed. Electronic paramagnetic resonance experiments confirm that CNOT and SWAP transitions are not forbidden.

Background: During the perioperative period an adequate intravascular volume must be maintained. Current recommendations overestimate perioperative volume requirements., Aim: To compare perioperative volume administration using standard monitoring methods or guided by left ventricular filling parameters., Material and Methods: Twenty-four patients subjected to colon resection were randomized to monitoring by electrocardiography, blood and central venous pressure, or by transesophageal echocardiography. In the latter, volume administration was adjusted to maintain basal values of left ventricular end diastolic volume and cardiac index., Results: Patients with the standard monitoring system and transesophageal echocardiographic monitoring received 21.1 ± 12 and 6.3 ± 2 ml/kg/h of fluids during the perioperative period, respectively (p < 0.01)., Conclusions: The use of transesophageal echocardiography significantly reduced the perioperative fluid administration.

We show that a crystal of mesoscopic Fe(8) single-molecule magnets is an experimental realization of the quantum Ising model in a transverse field, with dipolar interactions. Quantum annealing has enabled us to explore the quantum and classical phase transitions between the paramagnetic and ferromagnetic phases, at thermodynamical equilibrium. The phase diagram and critical exponents that we obtain agree with expectations for the mean-field universality class., (© 2011 American Physical Society)

The terdentate anionic picolinate-based nitronyl nitroxide (picNN) free radical forms neutral and robust homoleptic complexes with rare earth-metal ions. The nonacoordinated Tb(3+) complex Tb(picNN)(3)·6H(2)O is a single-molecule magnet with an activation energy barrier Δ = 22.8 ± 0.5 K and preexponential factor τ(0) = (5.5 ± 1.1) × 10(-9) s. It shows magnetic hysteresis below 1 K., (© 2011 American Chemical Society)

We report the synthesis, structures and magnetic properties of a series of chromium(III) metal-centered triangle (or "star") clusters, [Cr(4){RC(CH(2)O)(3)}(2)(4,4'-R'(2)-bipy)(3)Cl(6)] [R = Et, R' = H (2); R = HOCH(2), R' = H (3); R = Et, R' = (t)Bu (4)], prepared by two-step solvothermal reactions starting from [CrCl(3)(thf)(3)]. The product of the first stage of this reaction is the salt [Cr(bipy)(2)Cl(2)](2)[Cr(2)Cl(8)(MeCN)(2)] (1). In the absence of the diimine, a different family of tetrametallics is isolated: the butterfly complexes [Cr(4){EtC(CH(2)O)(3)}(2){NH(C(R)NH)(2)}(2)Cl(6)] (R = Me (5), Et (6), Ph (7)] where the chelating N-acetimidoylacetamidine NH(C(R)=NH)(2) ligands are formed in situ via condensation of the nitrile solvents (RCN) under solvothermal conditions. Magnetic measurements show the chromium stars to have an isolated S = 3 ground state, arising from antiferromagnetic coupling between the central and peripheral metal ions, analogous to the well-known Fe(III) stars. Bulk antiferromagnetic ordering is observed at 0.6 K. The butterfly complexes have a singlet ground state, with a low-lying S = 1 first excited state, due to dominant wing-body antiferromagnetic coupling.

Background: The Chilean Ministry of Health has implemented regulatory rules for the consumption of anti-biotics since September 1999, with sales restriction limited only with medical prescription., Aim: To analyze the impact of established regulatory measures from 2000 to 2008., Material and Methods: A retrospective analysis of antibiotics sales in pharmacies from 2000 to 2008 was performed. The information was obtained from the International Marketing System (IMS Health), an auditing system of pharmacy sales. The consumption unit used was the Defined Daily Dose per 1000 inhabitants/day (DDD)., Results: From 2000 to 2002 the regulatory rules had a great impact, but since 2002 the antibiotic consumption increased, especially amoxicillin, returning to similar levéis observed in 1998., Conclusions: The regulatory measures had an initial impact, but there was not reinforcement in the time and there was no further control. It is necessary to assume a permanent task and support of the authorities of health to edúcate the population about the implications of the inadequate use of antimicrobials and his effect on the microbial ecology.

We report a detailed experimental study of maghemite nanoparticles, with sizes ranging from 1.6 to 6 nm, synthesized inside a biological mould of apoferritin. The structural characterization of the inorganic cores, using TEM and x-ray diffraction, reveals a low degree of crystalline order, possibly arising from the nucleation and growth of multiple domains inside each molecule. We have also investigated the molecular structure by means of atomic force microscopy in liquid. We find that the synthesis of nanoparticles inside apoferritin leads to a small, but measurable, decrease in the external diameter of the protein, probably associated with conformational changes. The magnetic response of the maghemite cores has been studied by a combination of techniques, including ac susceptibility, dc magnetization and Mössbauer spectroscopy. From the equilibrium magnetic response, we have determined the distribution of magnetic moments per molecule. The results show highly reduced magnetic moments. This effect cannot be ascribed solely to the canting of spins located at the particle surface but, instead, it suggests that magnetoferritin cores have a highly disordered magnetic structure in which the contributions of different domains compensate each other. Finally, we have also determined, for each sample, the distribution of the activation energies required for the magnetization reversal and, from this, the size-dependent magnetic anisotropy constant K. We find that K is enormously enhanced with respect to the maghemite bulk value and that it increases with decreasing size. The Mössbauer spectra suggest that low-symmetry atomic sites, probably located at the particle surface and at the interfaces between different crystalline domains, are the likely source of the enhanced magnetic anisotropy.

In this work, we studied how an amphipathic peptide of the surface of the globular protein thioredoxin, TRX94-108, acquires a native-like structure when it becomes involved in an apolar interaction network. We designed peptide variants where the tendency to form alpha-helical conformation is modulated by replacing each of the leucine amino acid residues by an alanine. The induction of structure caused by sodium dodecyl sulfate (SDS) binding was studied by capillary zone electrophoresis, circular dichroism, DOSY-NMR, and molecular dynamics simulations (MDS). In addition, we analyzed the strength of the interaction between a C18 RP-HPLC matrix and the peptides. The results presented here reveal that (a) critical elements in the sequence of the wild-type peptide stabilize a SDS/peptide supramolecular cluster; (b) the hydrophobic nature of the interaction between SDS molecules and the peptide constrains the ensemble of conformations; (c) nonspecific apolar surfaces are sufficient to stabilize peptide secondary structure. Remarkably, MDS shed light on a contact network formed by a limited number of SDS molecules that serves as a structural scaffold preserving the helical conformation of this module. This mechanism might prevail when a peptide with low helical propensity is involved in structure consolidation. We suggest that folding of peptides sharing this feature does not require a preformed tightly-packed protein core. Thus, the formation of specific tertiary interactions would be the consequence of peptide folding and not its cause. In this scenario, folding might be thought of as a process that includes unspecific rounds of structure stabilization guiding the protein to the native state., (2010 Wiley-Liss, Inc.)

Two novel tetranuclear, star-shaped iron(III) clusters, [Fe(4)(acac)(6)(Br-mp)(2)] and [Fe(III) (4)(acac)(6)(tmp)(2)], are described. Both have S=5 ground states resulting from antiferromagnetic nearest-neighbour superexchange interactions, with J=-8.2 cm(-1) and J=-8.5 cm(-1) for 1 and 2, respectively. Energy barriers for the relaxation of the magnetisation of approximately 12 cm(-1) were derived from AC susceptibility measurements. Magnetic resonance measurements revealed a zero-field splitting parameter D=-0.34 cm(-1) for both complexes. AC susceptibility measurements in solution demonstrated that the complexes are reasonably stable in solution. Interestingly, the magnetisation relaxation slows down significantly in frozen solution, in contrast to what is generally observed for single-molecule magnets. This was shown to result from a large increase in tau(0), the prefactor in the Arrhenius equation, with the energy barrier remaining unchanged.

A new ligand has been synthesized with the aim of favoring distinct coordination environments within lanthanide polynuclear complexes. It has led to the formation of three unsymmetrical [Ln(III)(2)] (Ln = Gd, Tb, Eu) complexes, exhibiting weak antiferromagnetic coupling and, for Eu and Tb, high single-ion magnetic anisotropy. All of these attributes are necessary for these clusters to behave as possible 2qubit quantum gates.

We report the experimental results that show the operation of superconducting quantum interference device (SQUID) microsusceptometers immersed in the (3)He-(4)He mixture inside the mixing chamber of a dilution refrigerator at high frequency (1 MHz) and down to very low temperatures (13 mK). The devices are based on highly sensitive and easy-to-use commercial SQUID sensors. The integrated susceptometers are fabricated by rerouting some connections of the SQUID's input circuit. Examples of measurements on molecular magnets Mn(12) and HoW(10) are shown.

The equilibrium susceptibility of uniaxial paramagnets is studied in a unified framework which permits us to connect traditional results of the theory of quantum paramagnets, S = 1/2,1,3/2,..., with molecular magnetic clusters, S∼5,10,20 all the way up (S = 30,50,100,...,) to the theory of classical superparamagnets. This is done using standard tools of quantum statistical mechanics and linear-response theory (the Kubo correlator formalism). Several features of the temperature dependence of the susceptibility curves (crossovers, peaks, deviations from Curie law) are studied and their scalings with S identified and characterized. Both the longitudinal and transverse susceptibilities are discussed, as well as the response of the ensemble with anisotropy axes oriented at random. For the latter case a simple approximate formula is derived too, and its range of validity assessed, which could be used in the modelization of experiments.

The first two families of polyoxometalate-based single-molecule magnets (SMMs) are reported here. Compounds of the general formula [Ln(W(5)O(18))(2)](9-) (Ln(III) = Tb, Dy, Ho, and Er) and [Ln(SiW(11)O(39))(2)](13-) (Ln(III) = Tb, Dy, Ho, Er, Tm, and Yb) have been magnetically characterized with static and dynamic measurements. Slow relaxation of the magnetization, typically associated with SMM-like behavior, was observed for [Ln(W(5)O(18))(2)](9-) (Ln(III) = Ho and Er) and [Ln(SiW(11)O(39))(2)](13-) (Ln(III) = Dy, Ho, Er, and Yb). Among them, only the [Er(W(5)O(18))(2)](9-) derivative exhibited such a behavior above 2 K with an energy barrier for the reversal of the magnetization of 55 K. For a deep understanding of the appearance of slow relaxation of the magnetization in these types of mononuclear complexes, the ligand-field parameters and the splitting of the J ground-state multiplet of the lanthanide ions have been also estimated.

Intravenous antimicrobial consumption has not been evaluated previously in Chile. In order to know this consumption (in DDD per 100 bed days), associated factors and antimicrobial control systems across the country, a questionnaire was sent to evaluate these features during 2005. A total of 29 public hospitals and private clinics answered this poll, 20 belonging to the public health system (69%). Only 48.1% declared to have an independent antimicrobial committee and 17.2% allowed unrestricted antimicrobial use. Glycopeptides and carbapenems were the most regulated compounds (75.9 and 82.8%, respectively). Antimicrobial controls systems were more frequently declared among public hospitals and only non-public hospitals permitted free use of antimicrobials. Global consumption reached 59.98 DDD per 100 bed-days, with beta-lactams representing 74.3% of this consume (44.57 DDD per 100), and cephalosporins 43% (25.78 DDD per 100). Chloramphenicol, penicillin G and cloxacillin use was significantly higher among public hospitals. The opposite was observed for imipenem-cilastatin, linezolid, cefuroxime and caspofungin with higher consumes observed among non-public hospitals. In a multivariate analysis, increased cefazolin use was independently associated with sites allowing unrestricted use, and ciprofloxacin consumption with non-public hospitals. Institutions with decreased susceptibility to imipenem-cilastatin among non-fermentative gram negative bacilli showed a higher use of this compound and linezolid consumption paralleled vancomycin-resistant enterococci prevalence. It is necessary to reinforce governmental regulations about antimicrobial use issued during 1999.

Despite recent progress in understanding membrane protein folding, little is known about the mechanisms stabilizing these proteins. Here we characterize the kinetic thermal stability of CopA, a thermophilic P(IB)-type Cu+-ATPase from Archaeoglobus fulgidus. When heterologously expressed in Escherichia coli, purified and reconstituted in mixed micelles, CopA retained thermophilic characteristics with maximum activity at 75 degrees C. Incubation of CopA in the absence of substrates at temperatures in the 66-85 degrees C range led to an irreversible exponential decrease in enzyme activity suggesting a two-state process involving fully-active and inactive molecules. Although CopA inactivated much slower than mesophilic proteins, the activation energy was similar to that observed for mesophilic P-type ATPases. The inactivation process was found to be associated with the irreversible partial unfolding of the polypeptide chain, as assessed by Trp fluorescence, Phe UV spectroscopy, far UV circular dichroism, and 1-aniline-8-naphtalenesulfonate binding. However, the inactive thermally denatured protein still conserves large hydrophobic regions and considerable secondary structure.

Metal-organic sub-50 nm spherical particles that exhibit single-molecule magnet behaviour have been fabricated by direct precipitation of Mn(12)O(12) clusters in a mixture of acetonitrile and toluene.

A highly asymmetric Ni(II) cluster [Ni(4)(OH)(OMe)(3)(Hphpz)(4)(MeOH)(3)](MeOH) (1) (H(2)phpz=3-methyl-5-(2-hydroxyphenyl)pyrazole) has been prepared and its structure determined by means of single-crystal X-ray diffraction by using synchrotron radiation. Variable-temperature bulk-magnetization measurements show that the complex exhibits intramolecular-ferromagnetic interactions leading to a spin ground state S=4 with close-lying excited states. Magnetization and high-frequency EPR measurements suggest the presence of sizable Ising-type magnetic anisotropy, with zero-field splitting parameters D=-0.263 cm(-1) and E=0.04 cm(-1) for the spin ground state, and an isotropic g value of 2.25. The presence of both axial and transverse anisotropy was confirmed through low-temperature specific heat determinations down to 300 mK, but no slow relaxation of the magnetization was observed by AC measurements down to 1.8 K. Interestingly, AC susceptibility measurements down to temperatures as low as 23 mK showed no indication of slow relaxation of the magnetization in 1. Thus, despite the presence of an anisotropy barrier (U approximately 4.21 cm(-1) for the purely axial limit), the magnetization relaxation remains extremely fast down to the lowest temperatures. The estimated quantum tunneling rate, Gamma>0.667 MHz, makes this complex a prime candidate for observation of coherent tunneling of the magnetization.

CopA, a thermophilic ATPase from Archaeoglobus fulgidus, drives the outward movement of Cu(+) across the cell membrane. Millimolar concentration of Cys dramatically increases ( congruent with 800%) the activity of CopA and other P(IB)-type ATPases (Escherichia coli ZntA and Arabidopsis thaliana HMA2). The high affinity of CopA for metal ( congruent with 1 microM) together with the low Cu(+)-Cys K(D) (<10(-10)M) suggested a multifaceted interaction of Cys with CopA, perhaps acting as a substitute for the Cu(+) chaperone protein present in vivo. To explain the activation by the amino acid and further understand the mechanism of metal delivery to transport ATPases, Cys effects on the turnover and partial reactions of CopA were studied. 2-20 mM Cys accelerates enzyme turnover with little effect on CopA affinity for Cu(+), suggesting a metal independent activation. Furthermore, Cys activates the p-nitrophenyl phosphatase activity of CopA, even though this activity is metal independent. Cys accelerates enzyme phosphorylation and the forward dephosphorylation rates yielding higher steady state phosphoenzyme levels. The faster dephosphorylation would explain the higher enzyme turnover in the presence of Cys. The amino acid has no significant effect on low affinity ATP K(m) suggesting no changes in the E(1)<-->E(2) equilibrium. Characterization of Cu(+) transport into sealed vesicles indicates that Cys acts on the cytoplasmic side of the enzyme. However, the Cys activation of truncated CopA lacking the N-terminal metal binding domain (N-MBD) indicates that activation by Cys is independent of the regulatory N-MBD. These results suggest that Cys is a non-essential activator of CopA, interacting with the cytoplasmic side of the enzyme while this is in an E1 form. Interestingly, these effects also point out that Cu(+) can reach the cytoplasmic opening of the access path into the transmembrane transport sites either as a free metal or a Cu(+)-Cys complex.

With the intention of quantifying what occurs, between the members of the equipment of health in the public and deprived scope of the city of Cordoba, the present investigation is carried out. Comparative cross-sectional design observacional on stratified sample of doctors and fisioterapeutas. The data collection was made by means of survey of car-reports of "Maslach Burnout Inventory" (MBI). 479 professionals were studied, 22.3% (107) they were Fisioterapeutas and Kinesiólogos and 77.7% (372) Doctors of different specialties. It is possible to be concluded that in the public scope, the values of emotional fatigue are in the published ranks, despersonalizaci6n and lack of personal accomplishment is smaller. Between the hospitals they do not differ significantly. In the General Hospital of the Provincial scope, the Burnout is similar to the one of other countries and superior to the one of both local. In the private scope the levels of emotional fatigue are significantly greater than in the public, in the Service of Emergency the values exceed the published ranks. Between Pre-Residentes, the stress levels are moderate and they do not seem to vary; the Burnout would be below the awaited levels. Stress average of fisioterapeutas and kinesiólogos is in moderate levels and is smaller to the one of doctors of the public scope of the city of Cordova, but comparable to the one of the clinical residents and. The specialists Legal Medicine of the Fiscal Public Ministry, present/display the highest percentage of syndrome of complete Burnout.

The functions of membrane proteins are highly dependent on their phospholipid environment. In this article, we have used a hydrophobic photolabeling method to study the noncovalent interactions between plasma membrane calcium pump (PMCA) and surrounding phospholipids. With this approach, we determined (1) the number of lipid molecules in close contact with the transmembrane surface, i.e., the lipid-protein stoichiometry, and (2) the distribution of lipid molecules among different regions of the protein. PMCA was photolabeled in mixed micelles containing detergent, the phosphatidylcholine photoactivatable analog 1-palmitoyl-2-[9-[2'-[125I]iodo-4'- (trifluoromethyldiazirinyl)-benzyloxycarbonyl]-nonaoyl]-sn-glycero-3-phosphocholine, and different amounts of dimyristoyl phosphatidylcholine (PC). The stoichiometry was estimated after the extent of the labeling reaction had been independently assessed. We determined a maximum number of 17 +/- 1 molecules of PC in close contact with the transmembrane surface per PMCA molecule. In addition, a semiquantitative description of the phospholipid environment around different regions of PMCA was carried out after limited proteolysis of the photolabeled protein. The distribution of labels among the N-terminal (1-322), the central (323-660), and the C-terminal (661-1,205) regions was 26, 36, and 38%, respectively.

Time-dependent specific heat experiments on the molecular nanomagnet Fe8 and the isotopic enriched analogue 57Fe8 are presented. The inclusion of the 57Fe nuclear spins leads to a huge enhancement of the specific heat below 1 K, ascribed to a strong increase in the spin-lattice relaxation rate gamma arising from incoherent, nuclear-spin-mediated magnetic quantum tunneling (MQT) in the ground doublet. Since gamma is found comparable to the expected tunneling rate, the MQT process has to be inelastic. A model for the coupling of the tunneling spins to the lattice is presented. Under transverse field, a crossover from nuclear-spin-mediated to phonon-induced tunneling is observed.

We use neutron diffraction to probe the magnetization components of a crystal of Mn12 single-molecule magnets. Each of these molecules behaves, at low temperatures, as a nanomagnet with spin S = 10 and strong anisotropy along the crystallographic c axis. The application of a magnetic field H(perpendicular) perpendicular to c induces quantum tunneling between opposite spin orientations, enabling the spins to attain thermal equilibrium. For T approximately < 0.9(1) K, this equilibrium state shows spontaneous magnetization, indicating the onset of ferromagnetism. These long-range magnetic correlations nearly disappear for mu0H(perpendicular) approximately > 5.5 T, possibly suggesting the existence of a quantum critical point.

Malignant middle cerebral territory infarction represents 5 to 10% of all brain infarctions. Its mortality is 80%, due to brain herniation and it is not reduced by medical treatment. Decompressive hemicraniectomy reduces mortality to 12%, and the subsequent quality of life of patients is acceptable. We report two male patients aged 61 and 54 years, with a malignant middle cerebral territory infarction who were treated with decompressive hemicraniectomy. After two years of follow up, both patients are self-sufficient and live at home with their families.

Polysaccharide 23 valent pneumococcal vaccine commercially available from 1983 includes 23 serotypes of Streptococcus pneumoniae, representing near 90% of strains involved in invasive pneumococcal disease in immune competent adults. Vaccine confers protection against invasive pneumococcal disease. Immunization is recommended in adults over 65 years old, in patients affected by chronic diseases (cardiopathies, COPD, nephropathies, diabetes mellitus, hepatic cirrhosis, chronic breakage in brain-blood barrier, functional or anatomical asplenia, alcoholism), in immunocompromised hosts, including HIV infection, chemotherapy treatment and hematological malignancies. Influenza vaccine is prepared with particulated antigens, including two influenza A strains and one influenza B strain, selected according to influenza epidemiological worldwide surveillance the year before. On account of continuous antigenic changes (drifts), it is necessary to modify the vaccine antigen's composition yearly. Cost/effectiveness evaluation has confirmed the efficacy of influenza vaccine in reducing morbidity and mortality associated to influenza epidemic and health economical resources involved in patient care. Besides, clinical trials have confirmed that immunization reduces the risk of acquiring pneumonia, of hospitalization and death in elderly people during the influenza epidemic, when vaccine antigenic composition is similar to the circulating strains. Vaccination is recommended annually in healthy adults over 65 years old, in patients with chronic diseases (cardiopathies, COPD, nephropathies, diabetes mellitus, hepatic cirrhosis, chronic breakage of blood-brain barrier, functional or anatomical asplenia, alcoholism). It is also recommended in women who will be in the second or third trimester of pregnancy during the influenza season, in immunocompromised hosts, in institutionalized patients (geriatrics), health care workers, and travelers to geographical areas that are affected by the influenza epidemic.

Can magnetic interactions between single-molecule magnets (SMMs) in a crystal establish long-range magnetic order at low temperatures deep in the quantum regime, where the only electron spin fluctuations are due to incoherent magnetic quantum tunneling (MQT)? Put inversely: can MQT provide the temperature dependent fluctuations needed to destroy the ordered state above some finite T(c), although it should basically itself be a T-independent process? Our experiments on two novel Mn4 SMMs provide a positive answer to the above, showing at the same time that MQT in the SMMs has to involve spin-lattice coupling at a relaxation rate equaling that predicted and observed recently for nuclear-spin-mediated quantum relaxation.