A case of acute myocardial infarction in paced rhythm. Utility of the Barcelona algorithm.

We describe the case of a 70-year-old man with a pacemaker implant who presented to us with atypical chest pain. His admission ECG did not satisfy the criteria for myocardial infarction according to standard Sgarbossa criteria, and Smith modified Sgarbossa criteria. However, we applied the recently developed Barcelona algorithm, which is used to diagnose acute myocardial infarction in the presence of intrinsic left bundle branch block.Electrocardiographic criteria for an acute myocardial infarction were met. Lead V6 displayed a low voltage QRS complex (3 mm) with 1 mm ST depression, satisfying the Barcelona criteria for acute myocardial infarction. He underwent primary angioplasty for critical in-stent restenosis of the left anterior descending coronary artery. This is the first case report, to the best of our knowledge, where Barcelona algorithm has been used to diagnose acute coronary syndrome in right-ventricular paced rhythm.

Effect of Si substitution in ferromagnetic Pr2Fe17: a magnetocaloric material with zero thermal expansion operative at high temperature.

This article deals with the magnetic and thermal expansion properties of Pr2Fe16Si. This compound has been well characterized from the structural point of view by analysing X-ray diffraction (XRD) patterns. The temperature dependent behaviour of magnetization (M) and the structural parameters (lattice parameters, unit cell volume) suggest that the compound undergoes a second order phase transition from a paramagnetic to a ferromagnetic state at TC = 390 K, driven by an increase in bond length between iron atoms at 6c sites. The field-dependent behaviour of M below TC, and comparatively lower value of coercivity (Hc) have been explained by the role of Si atoms as pinning centres. In the ferromagnetic phase, the system is found to behave like an inhomogenous mean field system. The study of thermal expansion properties establishes that the compound is a zero thermal expansion material (αv = 5.3 × 10-6 K-1) operative in the temperature range T = 200-340 K. As a magnetocaloric material, Pr2Fe16Si possesses high RCP (87 J kg-1 at µ0H = 1.5 T), high operating temperature (390 K) and moderate |ΔSM|max.

Physical properties of RIr3 (R = Gd, Tb, Ho) compounds with coexisting polymorphic phases.

The binary compounds GdIr3, TbIr3 and HoIr3 are synthesized successfully and found to form with macroscopic co-existence of two polymorphic phases: AuBe5 (C15b) and AuCu3-type. The dc magnetization and heat capacity studies confirm that the C15b phase orders ferromagnetically, whereas the AuCu3 phase remains paramagnetic down to 2 K. The frequency dependent ac-susceptibility data, time dependent magnetic relaxation behavior and magnetic memory effect studies suggest that TbIr3 and HoIr3 are cannonical spin-glass systems, but no glassy feature could be found in GdIr3. The critical behavior of all three compounds has been investigated using the magnetization and heat capacity measurements around the transition temperature (TC). The critical exponents α, ß, γ and δ have been estimated using different techniques such as the Arrott-Noakes plot, Kouvel-Fisher plot and critical isotherm as well as analysis of specific heat data and study of magnetocaloric effect. The critical analysis study identifies the type of universal magnetic class in which the three compounds belong.

Transverse vibration driven large uniaxial negative and zero thermal expansion in boron bridged REPt3B framework materials.

In this work anomalous uniaxial thermal expansion behaviour at low temperatures along the c-direction of the tetragonal phase of different members of the antiperovskite REPt3B (RE = Sm, Gd-Tm) compounds is reported. Negative or zero thermal expansion (NTE/ZTE) behaviour in these compounds arises due to the transverse vibration of boron atoms in the linear Pt-B-Pt linkage. The coefficient of thermal expansion along the c-axis tends to become more negative in annealed compounds in comparison to those estimated for as-cast samples. While the as-cast TmPt3B and HoPt3B exhibit essentially ZTE behaviour, the NTE coefficient of annealed GdPt3B (∼-28 ppm K-1) is found to be even larger than that of the well known framework material ZrW2O8 (∼-9 ppm K-1) reported in the literature.

Chemical disorder driven reentrant spin cluster glass state formation and associated magnetocaloric properties of Nd2Ni0.94Si2.94.

In this work, we report the synthesis of a new ternary intermetallic compound, Nd2Ni0.94Si2.94, that forms in single phase only in a defect crystal structure. The compound exhibits an antiferromagnetic transition below 7.2 K (TN) followed by a spin cluster freezing behaviour below 2.85 K (Tf), which makes the compound a reentrant spin cluster glass system. The detailed studies of dc and ac magnetization, heat capacity, non-equilibrium dynamical behaviour, viz., aging effect, temperature and field dependent magnetic relaxation and magnetic memory effect establish the compound to be a cluster-glass material below freezing temperature. The interplay between competing exchange coupling (c/a ≃ 1.04 ⇒ JNN ≃ JNNN) and chemical disorder driven variation in the electronic environment among the Nd ions has been argued to be responsible for such a metastable state formation. A considerable value of MCE parameters (-ΔS ∼ 11.4 J kg-1 K-1, RCP ∼ 160 J kg-1 and ΔTad ∼ 5.2 K for a field change of 70 kOe) is obtained for this magnetically frustrated glassy compound.

Observation of short range order driven large refrigerant capacity in chemically disordered single phase compound Dy2Ni0.87Si2.95.

In this work, we report the successful synthesis of a new intermetallic compound Dy2Ni0.87Si2.95 forming in single phase only with a chemically disordered structure. The random distribution of Ni/Si and crystal defects create a variation in the local electronic environment between the magnetic Dy ions. In the presence of both disorder and competing exchange interactions driven magnetic frustration, originating due to c/a ∼ 1, the compound undergoes spin freezing behaviour below 5.6 K. In the non-equilibrium state below the spin freezing behaviour, the compound exhibits aging phenomena and magnetic memory effects. In the magnetically short-range ordered region, much above the freezing temperature, an unusual occurrence of considerable magnetic entropy change, -ΔSmaxM ∼ 21 J kg-1 K-1 with large cooling power RCP ∼ 531 J kg-1 and adiabatic temperature change, ΔTad ∼ 10 K for a field change of 70 kOe, is observed for this short range ordered cluster-glass compound without any magnetic hysteresis loss.

Atrial fibrillation and stroke prevention: is warfarin still an option?--No.

Atrial fibrillation is a common arrhythmia that increases the risk of stroke by 4.5 times. Anticoagulant/antithrombotic therapy in atrial fibrillation has been inconsistent and inappropriate. Warfarin enjoyed the monopoly of being the primary medication used to reduce the risk of thromboembolic events. Warfarin has many limitations in its use as an ideal anticoagulant. To overcome this difficulty, now there are two main alternative groups to warfarin namely, direct thrombin inhibitors (ximelagatran and dabigatran) and factor Xa inhibitors (apixaban, rivaroxaban, edoxaban, etc.). The advantages of the newer anticoagulants over the conventional warfarin are numerous. There are three landmark trials which have shown some light to the path of newer anticoagulant era, which include the following: RE-LY, ROCKET AF and ARISTOTLE. Head to head comparison of warfarin with newer anticoagulants showed the superiority of newer anticoagulants over warfarin in terms of efficacy and favorable side effect profile. After few decades of using warfarin, it's high time to enter into the era of newer anticoagulants and bid adieu to warfarin.

Global oral health inequalities: oral infections-challenges and approaches.

Four oral mucosal infections were identified as Global Oral Health Priorities: (a) HIV and associated viral, bacterial, and fungal infections; (b) tuberculosis; (c) NOMA; and (d) sexually transmitted diseases. Huge global inequalities exist in all four. HIV-associated infections constitute the major challenge. Oral manifestations of AIDS can be specifically diagnostic, indicating a significant role for dentists within health teams. The World Workshops in Oral Health & Disease in AIDS have identified a research program, elements of which are being implemented. Data on oral mucosal involvement in tuberculosis, syphilis, and gonorrhea are incomplete in developed countries and virtually non-existent in low- and middle-income countries, indicating the need for further epidemiological studies. Oral manifestations of tuberculosis and sexually transmitted diseases are largely associated with general health, so action programs should be integrated with agencies treating the systemic diseases. NOMA is very much in the oral health domain. It is a preventable disease associated with malnutrition and unidentified bacterial factors. Prevalence is probably grossly overestimated at present; but nevertheless it constitutes a challenge to the profession, especially in the NOMA belt. Current treatment is surgical, but plans for its eradication should be achievable. The global oral health community, especially the IADR, has a major role to play.

Complex magnetic properties associated with competing local and itinerant magnetism in [Formula: see text].

Ternary intermetallic compound [Formula: see text] has been synthesized in single phase and characterized by x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX) analysis, magnetization, heat capacity, neutron diffraction and muon spin rotation/relaxation ([Formula: see text]SR) measurements. The polycrystalline compound was synthesized in single phase by introducing necessary vacancies in Co/Si sites. Magnetic, heat capacity, and zero-field neutron diffraction studies reveal that the system undergoes magnetic transition below [Formula: see text]4 K. Neutron diffraction measurement further reveals that the magnetic ordering is antiferromagnetic in nature with an weak ordered moment. The high temperature magnetic phase has been attributed to glassy in nature consisting of ferromagnetic clusters of itinerant (3d) Co moments as evident by the development of internal field in zero-field [Formula: see text]SR below 50 K. The density-functional theory (DFT) calculations suggest that the low temperature magnetic transition is associated with antiferromagnetic coupling between Pr 4f and Co 3d spins. Pr moments show spin fluctuation along with unconventional orbital moment quenching due to crystal field. The evolution of the symmetry and the crystalline electric field environment of Pr-ions are also studied and compared theoretically between the elemental Pr and when it is coupled with other elements such as Co. The localized moment of Pr 4f and itinerant moment of Co 3d compete with each other below [Formula: see text]20 K resulting in an unusual temperature dependence of magnetic coercivity in the system.

Studies on magnetocaloric effect of Tb2Ni0.90Si2.94 compound.

A comparative study has been carried out on the magnetocaloric properties of as-cast and annealed Tb2Ni0.90Si2.94 intermetallic compound. While the as-cast material exhibits ferromagnetic cluster-glass behaviour below 9.9 K coexisting with antiferromagnetic (AFM) interaction, the annealed system shows AFM ordering below 13.5 K and spin freezing occurs below 4 K. The compound exhibits moderate magnetocaloric performance with maximum isothermal entropy changes (-ΔS M) 8.8 and 10.9 J kg-1 K-1, relative cooling power (RCP) 306 and 365 J kg-1, along with adiabatic temperature change (ΔT ad) 5.5 and 8.15 K for 70 kOe magnetic field change in as-cast and annealed forms, respectively. The estimated magnetic entropy change is found to be larger for annealed sample in comparison to that of as-cast analogue. However, the full width at half maxima (FWHM) of -ΔS M(T) behaviour is larger in as-cast compound due to the presence of inherent structural disorder which reduces with thermal annealing. A positive isothermal entropy change (-ΔS M) and adiabatic temperature change (ΔT ad) is observed for the as-cast compound in the measured field and temperature region. In contrast, the annealed system exhibits inverse magnetocaloric effect in the low field and temperature region where AFM interactions dominate. Magnetocaloric effect (MCE) is used as a tool to establish a subtle correlation between the observed magnetocaloric effect and the reported magnetic properties of the system.

Evolutionarily conserved pathways of energetic connectivity in protein families.

For mapping energetic interactions in proteins, a technique was developed that uses evolutionary data for a protein family to measure statistical interactions between amino acid positions. For the PDZ domain family, this analysis predicted a set of energetically coupled positions for a binding site residue that includes unexpected long-range interactions. Mutational studies confirm these predictions, demonstrating that the statistical energy function is a good indicator of thermodynamic coupling in proteins. Sets of interacting residues form connected pathways through the protein fold that may be the basis for efficient energy conduction within proteins.

Photoreceptor deactivation and retinal degeneration mediated by a photoreceptor-specific protein kinase C.

The protein kinase C (PKC) family of serine-threonine kinases has been implicated in the regulation of a variety of signaling cascades. One member of this family, eye-PKC, is expressed exclusively in the Drosophila visual system. The inaC (inactivation-no-afterpotential C) locus was shown to be the structural gene for eye-PKC. Analysis of the light response from inaC mutants showed that this kinase is required for the deactivation and rapid desensitization of the visual cascade. Light adaptation was also defective in inaC mutant flies. In flies carrying the retinal degeneration mutation rdgB, absence of eye-PKC suppressed photoreceptor cell degeneration. These results indicate that eye-PKC functions in the light-dependent regulation of the phototransduction cascade in Drosophila.

Arrestin function in inactivation of G protein-coupled receptor rhodopsin in vivo.

Arrestins have been implicated in the regulation of many G protein-coupled receptor signaling cascades. Mutations in two Drosophila photoreceptor-specific arrestin genes, arrestin 1 and arrestin 2, were generated. Analysis of the light response in these mutants shows that the Arr1 and Arr2 proteins are mediators of rhodopsin inactivation and are essential for the termination of the phototransduction cascade in vivo. The saturation of arrestin function by an excess of activated rhodopsin is responsible for a continuously activated state of the photoreceptors known as the prolonged depolarized afterpotential. In the absence of arrestins, photoreceptors undergo light-dependent retinal degeneration as a result of the continued activity of the phototransduction cascade. These results demonstrate the fundamental requirement for members of the arrestin protein family in the regulation of G protein-coupled receptors and signaling cascades in vivo.

Negative pressure driven valence instability of Eu in cubic Eu(0.4)La(0.6)Pd(3).

We report the change in the valency of Eu-ions in the binary intermetallic cubic compound EuPd(3) induced by La doping at rare-earth sites. Doping of La generates negative chemical pressure in the lattice, resulting in a significant increase of the lattice parameter without altering the simple-cubic structure of the compound. Results of dc-magnetic measurements suggest that this increase in the lattice parameter is associated with the valence transition of Eu-ions from Eu(3+) to a mixed-valent state. As Eu(2+)-ions possess a large magnetic moment, this valence transition significantly modifies the magnetic behavior of the compound. In contrast to introducing boron at the vacant body center site of the unit cell to change the valency of Eu-ions, as in the case of EuPd(3)B, our results suggest it can also be altered by doping a rare-earth ion of larger size at the lattice site of Eu in EuPd(3).

Spatial localization of the K+ channel selectivity filter by mutant cycle-based structure analysis.

The structurally well-characterized scorpion toxin Agitoxin2 inhibits ion permeation through Shaker K+ channels by binding to the external pore entryway. Scanning mutagenesis identified a set of inhibitor residues critical for making energetic contacts with the channel. Using thermodynamic mutant cycle analysis, we have mapped channel residues relative to the known inhibitor structure. This study constrains the position of multiple channel residues within the pore-forming loops; in one stretch, we have been able to map five out of seven contiguous residues to the inhibitor interaction surface, including those involved in ion selectivity. One interaction in particular, that of K27M on the inhibitor with Y445F on the channel, is unique in that it depends on the K+ ion concentration. These results reveal a shallow vestibule formed by the pore loops at the K+ channel entryway. The selectivity filter is located at the center of the vestibule close to (approximately 5 A) the extracellular solution.

C. elegans locomotory rate is modulated by the environment through a dopaminergic pathway and by experience through a serotonergic pathway.

Caenorhabditis elegans modulates its locomotory rate in response to its food, bacteria, in two ways. First, well-fed wild-type animals move more slowly in the presence of bacteria than in the absence of bacteria. This basal slowing response is mediated by a dopamine-containing neural circuit that senses a mechanical attribute of bacteria and may be an adaptive mechanism that increases the amount of time animals spend in the presence of food. Second, food-deprived wild-type animals, when transferred to bacteria, display a dramatically enhanced slowing response that ensures that the animals do not leave their newly encountered source of food. This experience-dependent response is mediated by serotonergic neurotransmission and is potentiated by fluoxetine (Prozac). The basal and enhanced slowing responses are distinct and separable neuromodulatory components of a genetically tractable paradigm of behavioral plasticity.

Cytosolic calcium transients: spatial localization and role in Drosophila photoreceptor cell function.

Drosophila phototransduction is a phosphoinositide-mediated and Ca(2+)-regulated signaling cascade ideal for the dissection of feedback regulatory mechanisms. To study the roles of intracellular Ca2+ ([Ca2+]i) in this process, we developed novel techniques for the measurement of [Ca2+]i in intact photoreceptors. We genetically engineered flies that express a UV-specific rhodopsin in place of the normal rhodopsin, so that long wavelength light can be used to image [Ca2+]i changes while minimally exciting the photoreceptor cells. We show that activation with UV generates [Ca2+]i increases that are spatially localized to the rhabdomeres and that are entirely dependent on the influx of extracellular Ca2+. Application of intracellular Ca2+ chelators of varying affinities demonstrates that the Ca2+ influx initially generates a large-amplitude transient that is crucial for negative regulation. Internal Ca2+ stores were revealed by discharging them with thapsigargin. But, in contrast to proposals that IP3-sensitive stores mediate phototransduction, thapsigargin does not mimic or acutely interfere with photoexcitation. Finally, we identify a photoreceptor-specific PKC as essential for normal kinetics of [Ca2+]i recovery.

A molecular pathway for light-dependent photoreceptor apoptosis in Drosophila.

Light-induced photoreceptor apoptosis occurs in many forms of inherited retinal degeneration resulting in blindness in both vertebrates and invertebrates. Though mutations in several photoreceptor signaling proteins have been implicated in triggering this process, the molecular events relating light activation of rhodopsin to photoreceptor death are yet unclear. Here, we uncover a pathway by which activation of rhodopsin in Drosophila mediates apoptosis through a G protein-independent mechanism. This process involves the formation of membrane complexes of phosphorylated, activated rhodopsin and its inhibitory protein arrestin, and subsequent clathrin-dependent endocytosis of these complexes into a cytoplasmic compartment. Together, these data define the proapoptotic molecules in Drosophila photoreceptors and indicate a novel signaling pathway for light-activated rhodopsin molecules in control of photoreceptor viability.

Role of random magnetic anisotropy on the valence, magnetocaloric and resistivity properties in a hexagonal Sm2Ni0.87Si2.87 compound.

In this work, we report the effect of random magnetic anisotropy (RMA) on the valence, magnetocaloric and resistivity properties in a glassy intermetallic material Sm2Ni0.87Si2.87. On the basis of detailed studies on the valence band and core level electronic structure, we have established that both the Sm3+ and Sm2+ ions are present in the system, suggesting the compound to be of mixed valence in nature. The significant observation of positive magnetic entropy change in zero-field cooled measurement has been argued due to the presence of RMA that develops due to local electronic environmental variations between the rare-earth ions in the system. The quantum interference effect caused by the elastic electron-electron interaction is responsible for the resistivity upturn at low-temperature for this disordered metallic conductor.

Unusual bidirectional frequency dependence of dynamical susceptibility in hexagonal intermetallic Pr2Ni0.95Si2.95.

In this study, the synthesis of a novel ternary intermetallic compound Pr2Ni0.95Si2.95 forming in single phase only by deliberately introducing vacancies in Ni/Si site is reported. The detailed studies on dc magnetization, heat capacity, ac magnetization & associated dynamical scaling, different types of non-equilibrium dynamical behaviour, viz., magnetic relaxation behaviour as a function of wait time and temperature, aging phenomena, and magnetic memory effect firmly establish that the compound exhibits spin freezing behaviour below 3.3 K (Tf). However, below Tf, temperature dependence of ac susceptibility data exhibit an additional peak that shows reverse frequency dependence to that generally observed in a glassy system. The unusual bidirectional frequency dependence in a single magnetic system is of significant interest and rarely reported in literature. Competing exchange interaction arising from c/a ~ 1 and crystallographic randomness driven magnetic phase separation has been argued to be responsible for such observation. The reverse frequency shift of the low temperature peak has been described on the basis of a simple phenomenological model proposed in this work.