FNDC5/Irisin polymorphisms are associated with osteopenia in postmenopausal Mayan-Mestizo women.

OBJECTIVE: This study aimed to analyze the association between rs3480 and rs16835198 of FNDC5/Irisin and their haplotypes with variations in bone mineral density (BMD) and osteopenia/osteoporosis in postmenopausal Mayan-Mestizo women. METHODS: We studied 547 postmenopausal women of Maya-Mestizo origin. BMD was measured in the lumbar spine and total hip by dual-energy X-ray absorptiometry. DNA was obtained from blood leukocytes. rs3480 and rs16835198 of FNDC5/Irisin were studied using real-time PCR allelic discrimination. Differences between the means of BMD according to genotype were analyzed with covariance. Allele frequency differences were assessed by χ2 and logistic regression was used to test for associations. Pairwise linkage disequilibrium between polymorphisms was calculated by direct correlation r2, and haplotype analysis was conducted. RESULTS: Under a recessive model, we observed a significant association of rs3480 with the presence of osteopenia at the total hip and femoral neck (p = 0.008 and p = 0.003, respectively). For rs16835198, we found an association with osteopenia at the total hip and femoral neck in a dominant model (p = 0.043 and p = 0.009, respectively). CONCLUSIONS: We found an association of rs3480 with risk to present osteopenia at the total hip and femoral neck, while rs16835198 was associated as a protector for presence of osteopenia only at the femoral neck.

Real-space imaging of non-collinear antiferromagnetic order with a single-spin magnetometer.

Although ferromagnets have many applications, their large magnetization and the resulting energy cost for switching magnetic moments bring into question their suitability for reliable low-power spintronic devices. Non-collinear antiferromagnetic systems do not suffer from this problem, and often have extra functionalities: non-collinear spin order may break space-inversion symmetry and thus allow electric-field control of magnetism, or may produce emergent spin-orbit effects that enable efficient spin-charge interconversion. To harness these traits for next-generation spintronics, the nanoscale control and imaging capabilities that are now routine for ferromagnets must be developed for antiferromagnetic systems. Here, using a non-invasive, scanning single-spin magnetometer based on a nitrogen-vacancy defect in diamond, we demonstrate real-space visualization of non-collinear antiferromagnetic order in a magnetic thin film at room temperature. We image the spin cycloid of a multiferroic bismuth ferrite (BiFeO3) thin film and extract a period of about 70 nanometres, consistent with values determined by macroscopic diffraction. In addition, we take advantage of the magnetoelectric coupling present in BiFeO3 to manipulate the cycloid propagation direction by an electric field. Besides highlighting the potential of nitrogen-vacancy magnetometry for imaging complex antiferromagnetic orders at the nanoscale, these results demonstrate how BiFeO3 can be used in the design of reconfigurable nanoscale spin textures.

The nature of domain walls in ultrathin ferromagnets revealed by scanning nanomagnetometry.

The capacity to propagate magnetic domain walls with spin-polarized currents underpins several schemes for information storage and processing using spintronic devices. A key question involves the internal structure of the domain walls, which governs their response to certain current-driven torques such as the spin Hall effect. Here we show that magnetic microscopy based on a single nitrogen-vacancy defect in diamond can provide a direct determination of the internal wall structure in ultrathin ferromagnetic films under ambient conditions. We find pure Bloch walls in Ta/CoFeB(1 nm)/MgO, while left-handed Néel walls are observed in Pt/Co(0.6 nm)/AlOx. The latter indicates the presence of a sizable interfacial Dzyaloshinskii-Moriya interaction, which has strong bearing on the feasibility of exploiting novel chiral states such as skyrmions for information technologies.

Emission polarization control in semiconductor quantum dots coupled to a photonic crystal microcavity.

We study the optical emission of single semiconductor quantum dots weakly coupled to a photonic-crystal micro-cavity. The linearly polarized emission of a selected quantum dot changes continuously its polarization angle, from nearly perpendicular to the cavity mode polarization at large detuning, to parallel at zero detuning, and reversing sign for negative detuning. The linear polarization rotation is qualitatively interpreted in terms of the detuning dependent mixing of the quantum dot and cavity states. The present result is relevant to achieve continuous control of the linear polarization in single photon emitters.

Meningitis aguda iatrogénica postanestesia intradural por Streptococcus salivarius / No disponible

No disponible

Photophysical studies on antimalarial drugs.

Most drugs used in the treatment of malaria produce phototoxic side effects in both the skin and the eye. Cutaneous and ocular effects that may be caused by light include changes in skin pigmentation, corneal opacity, cataract formation and other visual disturbances including irreversible retinal damage (retinopathy) leading to blindness. The mechanism for these reactions in humans is unknown. We irradiated a number of antimalarial drugs (amodiaquine, chloroquine, hydroxychloroquine, mefloquine, primaquine and quinacrine) with light (lambda > 300 nm) and conducted electron paramagnetic resonance (EPR) and laser flash photolysis studies to determine the possible active intermediates produced. Each antimalarial drug produced at least one EPR adduct with the spin-trap 5,5-dimethyl-1-pyrroline N-oxide in benzene: superoxide/hydroperoxyl adducts (chloroquine, mefloquine, quinacrine, amodiaquine and quinine), carbon-centered radical adducts (all but primaquine), or a nitrogen-centered radical adduct only (primaquine). In ethanol all drugs except primaquine produced some superoxide/hydroperoxyl adduct, with quinine, quinacrine, and hydroxychloroquine also producing the ethoxyl adduct. As detected with flash photolysis and steady-state techniques, mefloquine, quinine, amodiquine and a photoproduct of quinacrine produced singlet oxygen ([symbol: see text]delta = 0.38; [symbol: see text]delta = 0.36; [symbol: see text]delta = 0.011; [symbol: see text]delta = 0.013 in D2O, pD7), but only primaquine quenched singlet oxygen efficiently (2.6 x 10(8) M-1 s-1 in D2O, pD7). Because malaria is a disease most prevalent in regions of high light intensity, protective measures (clothing, sunblock, sunglasses or eye wraps) should be recommended when administering antimalarial drugs.

Interfering with Greg Louganis, your sister's bobby pins and glycoprotein 41.

AIDS: The rate of HIV replication is estimated to be about 10 billion particles a day, and the cell's structure is its primary defense against infection. Cell membranes provide a defense against infection by forming a tight bond, preventing cells from being invaded by other organisms. The complex process of how HIV enters a cell is explained, and various parts of the process are illustrated. One key step in the process is fusion, which is when a virus particle attaches to a T cell, and the virus and cell merge together, allowing the virus to enter the cell. Researchers hope to find ways to interfere with fusion, so as to prevent HIV infection. Trimeris, Inc. has developed a new drug called T-20, or pentafuside, that is capable of preventing HIV from infecting a target cell. Results from studies of T-20 are provided, and ongoing studies are described.^ieng

Body changes and blood abnormalities: the lipodystrophy and fat redistribution conundrum.

AIDS: Both AIDS and antiretroviral treatments have been associated with body changes. The most common term used to characterize these changes is lipodystrophy. Body changes include increased abdominal girth, fat accumulation at the base of the neck, enlarged breasts in both sexes, loss of fat in the face and extremities, and the appearance of prominent veins. Blood abnormalities associated with the condition include insulin resistance and increased levels of cholesterol, triglycerides, and glucose. There may also be an increased risk of cardiac complications. Researchers are seeking the causes of the fat redistribution and lipid and glucose abnormalities. A discussion of managing and treating these conditions is included.^ieng

Ich bin eine Berliner: the hope for remission of HIV.

AIDS: Early in the AIDS epidemic, researchers had hoped to find a way to eradicate HIV from the body. It was soon realized that HIV can persist in long-lived, resting CD4 T cells, and total eradication of the virus is probably unlikely. However, scientists would like to duplicate the results of the HIV-infected Berlin patient who initially received an anti-HIV drug combination that lowered his viral load to below the lower limit of quantification. Eventually he discontinued treatment permanently. As of the 6th Conference on Retroviruses and Opportunistic Infections, the Berlin patient has shown no evidence of virologic rebound despite having discontinued his treatment. Although HIV was still detected in his lymph nodes and resting CD4 T cells, researchers believe his HIV is under control. Duplicating the results of the Berlin patient requires finding the answers to several key questions, such as whether treatment during acute infection is necessary and whether intermittent therapy is important. Some researchers are studying interleukin-2 (IL-2) to see if IL-2 can clear latent reservoirs of infected, resting CD4 T cells.^ieng

Why the fat lady hasn't sung: the limits of HAART.

AIDS: Despite the promise of highly active antiretroviral therapies (HAART) to potentially suppress HIV, the ability of the virus to hide in reservoirs makes HIV difficult to eradicate. The virus' ability to remain latent in cells, and continue to replicate, makes targeting and eliminating known reservoirs only a partial solution. Recognizing the continuing multiplication of viral cells may alter future treatment strategies. Following the theory of David Ho, MD, implementation of HAART produces a gradual decline in the levels of HIV. HAART protects new cells being produced, while older infected cells eventually die off. A more recent model concludes that HIV continues to infect new cells possibly because of non-uniform drug distribution to various tissues. The virus is produced in the lymphoid tissue in bursts, responding to the immune system. These "viral bursts" are diminished by HAART, which slowly decreases their size and number, and consequently decreases the number of new cells infected. The newer theory calls for less disturbance of latently infected cells, and greater use of drugs with the best pharmacokinetics, like ABT-378/r, efavirenz (Sustiva), Indinavir (Crixivan) and Ritonavir (Norvir).^ieng

How good does your virus look in a bikini? Or, does viral fitness matter?

AIDS: Many patients are experiencing viral breakthrough while using highly active antiretroviral therapy (HAART). Patients should prepare themselves for the likelihood of viral resistance and weigh their options in advance. One study showed that viral resistance to one protease inhibitor may be different from resistance to a different protease inhibitor. Cross-resistance between drugs also limits the number and types of regimens available to a patient who is undergoing breakthrough. A study by Richard D'Aquila, MD, and colleagues deduced that the timing of a change in protease-based treatment is important to the success of the transition. Further studies need to be conducted to apply this hypothesis to a wider variety of protease inhibitor therapies, but if it holds true, it could possibly alter the order in which certain protease inhibitors are prescribed to maximize effectiveness, and preserve viable subsequent treatments.^ieng

Antiretrovirals for the heavily experienced patient: hefty plans to holidays.

AIDS: When seeking alternative therapies for treatment-experienced patients, several issues must be addressed. Considerations for various therapies include determining what is an acceptable level of viral load to be achieved, and how many drugs should be used in combination regimens. Clinical data supporting these approaches are detailed. To provide effective treatments for experienced patients, pharmaceutical companies should design drugs that differ considerably from current drugs, which are achieving positive results mainly in treatment-naive populations. A glossary of terms used in the article is provided.^ieng

Characterization of the transient intermediates generated from the photoexcitation of nabumetone: a comparison with naproxen.

The photochemical and photophysical properties of nabumetone (4-[6-methoxy-2-naphthyl]-2-butanone) were examined employing conventional and time-resolved spectroscopic techniques. The naphthalene-like nabumetone triplet is formed with 29% efficiency in acetonitrile. Singlet oxygen formation was also detected in this solvent with a phi delta value of 0.19. A naphthalene-like radical cation absorption, formed via biphotonic processes, was also detected. The reactivity of both the triplet and radical cation of nabumetone toward different substrates was examined. The photochemical properties of nabumetone are compared with those of naproxen, a structurally related acidic nonsteroidal anti-inflammatory drug. For these two anti-inflammatory agents, a type II photosensitization process is most likely responsible for their phototoxicity.

The effects of custom tray material on the accuracy of master casts.

PURPOSE: The accuracy of master cast reproduction by a polyvinylsiloxane impression material using two visible-light-curing resin and an autopolymerizing polymethyl methacrylate resin custom tray materials was investigated. MATERIALS AND METHODS: Custom trays were fabricated from a master cast that had three index points marked on both the inner and outer vestibules. Impressions were made of the master cast using Extrude and then poured in Die Keen Green stone. The distances between the reproduced index points were measured to +/- 0.01 mm with a traveling microscope and the algebraic norms calculated for each tray material. RESULTS: No differences (p > .05) were found in the dimensions of the inner index points, while the separations of the outer index points indicated that there were differences in the accuracy of reproduction (p < .01) by the three tray materials. The index points reproduced on the casts, compared with the master cast, were closer together for the Triad Blue trays than for the TruTray and Ontray impression trays. CONCLUSIONS: All three tray materials produced acceptable casts, but the greatest accuracy was achieved with TruTray, followed by Ontray. Triad Blue produced casts that were slightly smaller than the master. In practice, the small measured differences in cast dimensions may not have clinical significance.

Influence of solvent polarity and proticity on the photochemical properties of norfloxacin.

The fluoroquinolone antibacterial norfloxacin (NF) is a moderate photosensitizer of singlet molecular oxygen (1O2). We have studied photosensitization by NF as a function of medium polarity and proticity in solvent mixtures. We have used 1,4-dioxane and propylene carbonate mixtures to keep proticity constant while modulating polarity, and water/D2O and ethylene carbonate mixtures to alter proticity without large changes in polarity. The absorption spectrum of NF was little affected by solvent changes, as compared to the fluorescence spectrum that exhibited as much as a 50 nm blue-shift, e.g. 1,4-dioxane versus D2O. The quantum yield of NF fluorescence saturated at an almost 10 times higher value (approximately 0.14) when proticity was increased by added water, up to 0.2 mol fraction, to ethylene carbonate. Less pronounced, the increasing polarity in 1,4-dioxane/propylene carbonate mixtures affected the fluorescence yield much less. Norfloxacin produces 1O2 and is able to quench 1O2. The rate constant for 1O2 quenching is 4.5 x 10(7) M-1 s-1 in propylene carbonate but decreases ca four times in D2O. The quantum yield of 1O2 photogeneration was also up to five times higher in solvents that were both protic and polar than vice versa. Our data show that NF is more photochemically active in an environment that is both protic and polar. This suggests the involvement of polar excited state(s) and possible proton/hydrogen transfer during photoexcitation. Similar processes may initiate the phototoxic response reported in some patients treated with the fluoroquinolone drugs. The phototoxicity of NF and other fluoroquinolone antibiotics may strongly depend on their localization in hydrophilic or hydrophobic cell/tissue regions.