883 resultados para Rapid solidification
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The range of novel psychoactive substances (NPS) including phenethylamines, cathinones, piperazines, tryptamines, etc. is continuously growing. Therefore, fast and reliable screening methods for these compounds are essential and needed. The use of dried blood spots (DBS) for a fast straightforward approach helps to simplify and shorten sample preparation significantly. DBS were produced from 10 µl of whole blood and extracted offline with 500 µl methanol followed by evaporation and reconstitution in mobile phase. Reversed-phase chromatographic separation and mass spectrometric detection (RP-LC-MS/MS) was achieved within a run time of 10 min. The screening method was validated by evaluating the following parameters: limit of detection (LOD), matrix effect, selectivity and specificity, extraction efficiency, and short-term and long-term stability. Furthermore, the method was applied to authentic samples and results were compared with those obtained with a validated whole blood method used for Routine analysis of NPS. LOD was between 1 and 10 ng/ml. No interference from Matrix compounds was observed. The method was proven to be specific and selective for the analytes, although with limitations for 3-FMC/flephedrone and MDDMA/MDEA. Mean extraction efficiency was 84.6 %. All substances were stable in DBS for at least a week when cooled. Cooling was essential for the stability of cathinones. Prepared samples were stable for at least 3 days. Comparison to the validated whole blood method yielded similar results. DBS were shown to be useful in developing a rapid screening method for NPS with simplified sample preparation. Copyright © 2013 John Wiley & Sons, Ltd
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Temporary transcoronary unipolar pacing is a validated simple, effective, and safe alternative to temporary transvenous pacing of the right ventricle for the treatment of relevant bradyarrhythmias complicating percutaneous coronary intervention. We describe the use of rapid transcoronary pacing to aid precise placement of a stent in the left main coronary artery bifurcation.
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Abstract We demonstrate the use of Fourier transform infrared spectroscopy (FTIRS) to make quantitative measures of total organic carbon (TOC), total inorganic carbon (TIC) and biogenic silica (BSi) concentrations in sediment. FTIRS is a fast and costeffective technique and only small sediment samples are needed (0.01 g). Statistically significant models were developed using sediment samples from northern Sweden and were applied to sediment records from Sweden, northeast Siberia and Macedonia. The correlation between FTIRS-inferred values and amounts of biogeochemical constituents assessed conventionally varied between r = 0.84–0.99 for TOC, r = 0.85– 0.99 for TIC, and r = 0.68–0.94 for BSi. Because FTIR spectra contain information on a large number of both inorganic and organic components, there is great potential for FTIRS to become an important tool in paleolimnology.
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Geochemical investigation of Martian meteorites (SNC meteorites) yields important constraints on the chemical and geodynamical evolution of Mars. These samples may not be representative of the whole of Mars; however, they provide constraints on the early differentiation processes on Mars. The bulk composition of Martian samples implies the presence of a metallic core that formed concurrently as the planet accreted. The strong depletion of highly siderophile elements in the Martian mantle is only possible if Mars had a large scale magma ocean early in its history allowing efficient separation of a metallic melt from molten silicate. The solidification of the magma ocean created chemical heterogeneities whose ancient origin is manifested in the heterogeneous 142Nd and 182W abundances observed in different meteorite groups derived from Mars. The isotope anomalies measured in SNC meteorites imply major chemical fractionation within the Martian mantle during the life time of the short-lived isotopes 146Sm and 182Hf. The Hf-W data are consistent with very rapid accretion of Mars within a few million years or, alternatively, a more protracted accretion history involving several large impacts and incomplete metal-silicate equilibration during core formation. In contrast to Earth early-formed chemical heterogeneities are still preserved on Mars, albeit slightly modified by mixing processes. The preservation of such ancient chemical differences is only possible if Mars did not undergo efficient whole mantle convection or vigorous plate tectonic style processes after the first few tens of millions of years of its history.
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A microbiopsy system for fast excision and transfer of biological specimens from donor to high-pressure freezer was developed. With a modified, commercially available, Promag 1.2 biopsy gun, tissue samples can be excised with a size small enough (0.6 mm x 1.2 mm x 0.3 mm) to be easily transferred into a newly designed specimen platelet. A self-made transfer unit allows fast transfer of the specimen from the needle into the specimen platelet. The platelet is then fixed in a commercially available specimen holder of a high-pressure freezing machine (EM PACT, Leica Microsystems, Vienna, Austria) and frozen therein. The time required by a well-instructed (but not experienced) person to execute all steps is in the range of half a minute. This period is considered short enough to maintain the excised tissue pieces close to their native state. We show that a range of animal tissues (liver, brain, kidney and muscle) are well preserved. To prove the quality of freezing achieved with the system, we show vitrified ivy leaves high-pressure frozen in the new specimen platelet.
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Endothelial function typically precedes clinical manifestations of cardiovascular disease and provides a potential mechanism for the associations observed between cardiovascular disease and sleep quality. This study examined how subjective and objective indicators of sleep quality relate to endothelial function, as measured by brachial artery flow-mediated dilation (FMD). In a clinical research centre, 100 non-shift working adults (mean age: 36 years) completed FMD testing and the Pittsburgh Sleep Quality Index, along with a polysomnography assessment to obtain the following measures: slow wave sleep, percentage rapid eye movement (REM) sleep, REM sleep latency, total arousal index, total sleep time, wake after sleep onset, sleep efficiency and apnea-hypopnea index. Bivariate correlations and follow-up multiple regressions examined how FMD related to subjective (i.e., Pittsburgh Sleep Quality Index scores) and objective (i.e., polysomnography-derived) indicators of sleep quality. After FMD showed bivariate correlations with Pittsburgh Sleep Quality Index scores, percentage REM sleep and REM latency, further examination with separate regression models indicated that these associations remained significant after adjustments for sex, age, race, hypertension, body mass index, apnea-hypopnea index, smoking and income (Ps < 0.05). Specifically, as FMD decreased, scores on the Pittsburgh Sleep Quality Index increased (indicating decreased subjective sleep quality) and percentage REM sleep decreased, while REM sleep latency increased (Ps < 0.05). Poorer subjective sleep quality and adverse changes in REM sleep were associated with diminished vasodilation, which could link sleep disturbances to cardiovascular disease.
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Agitation is a major problem in acute schizophrenia. Still, only limited evidence exists on antipsychotic efficacy in severely agitated patients after the first 24 hours. We aimed to investigate the efficacy of oral haloperidol, risperidone, and olanzapine in reducing psychotic agitation in severely agitated patients with schizophrenia or schizophreniform or schizoaffective disorder over 96 hours using a prospective, randomized, rater-blinded, controlled design within a naturalistic treatment regimen. We enrolled 43 severely agitated patients at acute care psychiatric units. Participants were randomly assigned to receive either daily haloperidol 15 mg, olanzapine 20 mg, or risperidone 2 – 6 mg over 5 days. Positive and Negative Syndrome Scale psychotic agitation (PANSS-PAS) subscore was the primary outcome variable. A mixed model analyses was applied. All drugs were effective for rapid tranquillization within 2 hours. Over 5 days, the course differed between agents (p < 0.001) but none was superior. Dropouts occurred only in the risperidone and olanzapine groups. Men responded better to treatment than women during the initial 2 hours (p = 0.046) as well as over the 5 day course (p < 0.001). No difference between drug groups was observed regarding diazepam or biperiden use. Oral haloperidol, risperidone, and olanzapine seem to be suitable for treating acute severe psychotic agitation in schizophrenia spectrum disorders. We observed a gender effect with poorer outcome in women.
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Studies were performed to test the hypothesis that type I hypersensitivity underlies worm induced intestinal fluid secretion and the rapid rejection of Trichinella spiralis from immunized rats, and the two events may be related in a cause-effect manner.^ Two approaches were taken. One was to determine whether inhibition of anaphylaxis-mediated Cl$\sp{-}$ and fluid secretion accompanying a secondary infection impedes worm rejection from immune hosts. The other was to determine whether induction of intestinal fluid secretion in nonimmune hosts interfered with worm establishment. In both studies, fluid secretion was measured volumetrically 30 min after a challenge infection and worms were counted.^ In immunized rats indomethacin did not affect the worm-induced fluid secretion when used alone, despite inhibiting mucosal prostaglandin synthesis. Fluid secretion was reduced by treatment with diphenhydramine and further reduced by the combination of diphenhydramine and indomethacin. The paradoxical effects of indomethacin when used alone compared with its coadministration with diphenhydramine is explained by the enhancing effect of indomethacin on histamine release. Abolishing net fluid secretion in these studies had no effect on rapid worm rejection in immune hosts.^ Worm establishment was reduced in recipients of immune serum containing IgE antibodies. Net intestinal fluid secretion induced in normal rats by PGE$\sb2$, cholera toxin, or hypertonic mannitol solution had no effect on worm establishment compared with untreated controls.^ In a related experiment, worm-induced intestinal fluid secretion and worm rejection in immune rats were partially blocked by concurrent injection with 5-HT$\sb2$ and 5-HT$\sb3$ blockers (Ketanserin and MDL-72222), suggesting that 5-HT is involved. This possible involvement was supported in that treatment of nonimmune rats with 5-HT significantly inhibited worm establishment in the intestine.^ Results indicate that anaphylaxis is the basis for both worm-induced intestinal fluid secretion and rapid rejection of T. spiralis in immune rats, but these events are independent of one another. 5-HT is a possible mediator of worm rejection, however, its mechanism of action is related to something other than fluid secretion. ^
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Recently it has been proposed that the evaluation of effects of pollutants on aquatic organisms can provide an early warning system of potential environmental and human health risks (NRC 1991). Unfortunately there are few methods available to aquatic biologists to conduct assessments of the effects of pollutants on aquatic animal community health. The primary goal of this research was to develop and evaluate the feasibility of such a method. Specifically, the primary objective of this study was to develop a prototype rapid bioassessment technique similar to the Index of Biotic Integrity (IBI) for the upper Texas and Northwestern Gulf of Mexico coastal tributaries. The IBI consists of a series of "metrics" which describes specific attributes of the aquatic community. Each of these metrics are given a score which is then subtotaled to derive a total assessment of the "health" of the aquatic community. This IBI procedure may provide an additional assessment tool for professionals in water quality management.^ The experimental design consisted primarily of compiling previously collected data from monitoring conducted by the Texas Natural Resource Conservation Commission (TNRCC) at five bayous classified according to potential for anthropogenic impact and salinity regime. Standardized hydrological, chemical, and biological monitoring had been conducted in each of these watersheds. The identification and evaluation of candidate metrics for inclusion in the estuarine IBI was conducted through the use of correlation analysis, cluster analysis, stepwise and normal discriminant analysis, and evaluation of cumulative distribution frequencies. Scores of each included metric were determined based on exceedances of specific percentiles. Individual scores were summed and a total IBI score and rank for the community computed.^ Results of these analyses yielded the proposed metrics and rankings listed in this report. Based on the results of this study, incorporation of an estuarine IBI method as a water quality assessment tool is warranted. Adopted metrics were correlated to seasonal trends and less so to salinity gradients observed during the study (0-25 ppt). Further refinement of this method is needed using a larger more inclusive data set which includes additional habitat types, salinity ranges, and temporal variation. ^
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1,25-dihydroxyvitamin D3 [1,25(OH)2D 3] exerts pleiotropic effects on osteoblasts via both long-term nuclear receptor-mediated and rapid membrane-initiated pathways during bone remodeling and mineral homeostasis. This study explored the membrane transducers that mediate rapid effects of 1,25(OH)2D3 on osteoblasts, including sphingomyelinase (SMase) and L-type voltage sensitive calcium channels (VSCCs). ^ It was previously demonstrated that 1,25(OH)2D3 stimulates transmembrane influx of Ca2+ through VSCCs in ROS 17/2.8 osteoblasts, however the molecular identity of 1,25(OH)2D 3-regulated VSCC has not been known. In this study, on the basis of in vitro tests of three unique ribozymes specifically cleaving a1C mRNA, I transfected ROS 17/2.8 cells with vectors coding recombinant ribozyme modified with U1 snRNA structure, and successfully selected stable clonal cells in which the expression of a1C was strikingly reduced. Ca2+ influx studies in these cells compared to control transfectants showed selective attenuation of depolarization- and 1,25(OH)2D3-regulated Ca2+ responses. These results allow us to conclude that the cardiac ( a1C ) subtype of the L-type VSCC is the major membrane transducer of Ca 2+ influx in osteoblasts. ^ I also demonstrated that 1,25(OH)2D3 induces a rapid hydrolysis of membrane sphingomyelin (SM) in ROS 17/2.8 cells, with the concomitant generation of ceramide, detectable at 15 minute, and maximal at 1 hour after addition. Sphingosine, sphingosine-1-phosphate (SPP) and sphingosylphosphorylcholine (SPC), downstream products of SM hydrolysis, but not ceramide, elicit Ca 2+ release from intracellular stores. Considering ceramide, sphingosine, and SPP as second messengers modulating intracellular kinases or phosphatases, these findings implicate sphingolipid-signaling pathways in transducing rapid effects of 1,25(OH)2D3 on osteoblasts. In structure/function analyses of sphingolipid signaling, it was observed that psychosine elicits Ca2+ release from intracellular stores. This challenges the dogma that sphingosine phosphorylation permits mobilization of Ca2+ , because psychosine is a sphingosine analog galactosylated at 1-carbon, preventing phosphorylation at that site. Psychosine is the pathological metabolite found in patients with Krabbe's disease, suggesting that psychosine disrupts the physiological sphingolipid signaling by chronic release of Ca2+ from intracellular stores. ^ Slower SM turnover than Ca2+ influx through VSCCs in response to 1,25(OH)2D3 demonstrates ceramide does not mediate the 1,25(OH)2D3-induced Ca2+ signaling, a conclusion endorsed further by the failure of ceramide to induce Ca 2+ signaling. ^
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OBJECTIVE: The study of HIV-1 rapid progressors has been limited to specific case reports. Nevertheless, identification and characterization of the viral and host factors involved in rapid progression are crucial when attempting to uncover the correlates of rapid disease outcome. DESIGN: We carried out comparative functional analyses in rapid progressors (n = 46) and standard progressors (n = 46) early after HIV-1 seroconversion (≤1 year). The viral traits tested were viral replicative capacity, co-receptor usage, and genomic variation. Host CD8 T-cell responses, humoral activity, and HLA immunogenetic markers were also determined. RESULTS: Our data demonstrate an unusual convergence of highly pathogenic HIV-1 strains in rapid progressors. Compared with standard progressors, rapid progressor viral strains show higher in-vitro replicative capacity (81.5 vs. 67.9%; P = 0.025) and greater X4/DM co-receptor usage (26.3 vs. 2.8%; P = 0.006) in early infection. Limited or absent functional HIV-1 CD8 T-cell responses and neutralizing activity were measured in rapid progressors. Moreover, the increase in common HLA allele-restricted CD8 T-cell escape mutations in rapid progressors acts as a signature of uncontrolled HIV-1 replication and early impairment of adaptive cellular responses. CONCLUSION: Our data support a dominant role for viral factors in rapid progressors. Robust HIV-1 replication and intrinsic viral properties limit host adaptive immune responses, thus driving rapid disease progression.
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We address under what conditions a magma generated by partial melting at 100 km depth in the mantle wedge above a subduction zone can reach the crust in dikes before stalling. We also address under what conditions primitive basaltic magma (Mg # >60) can be delivered from this depth to the crust. We employ linear elastic fracture mechanics with magma solidification theory and perform a parametric sensitivity analysis. All dikes are initiated at a depth of 100 km in the thermal core of the wedge, and the Moho is fixed at 35 km depth. We consider a range of melt solidus temperatures (800-1100 degrees C), viscosities (10-100 Pa s), and densities (2400-2700 kg m(-3)). We also consider a range of host rock fracture toughness values (50-300 MPa m(1/2)) and dike lengths (2-5 km) and two thermal structures for the mantle wedge (1260 and 1400 degrees C at 100 km depth and 760 and 900 degrees C at 35 km depth). For the given parameter space, many dikes can reach the Moho in less than a few hundred hours, well within the time constraints provided by U series isotope disequilibria studies. Increasing the temperature in the mantle wedge, or increasing the dike length, allows additional dikes to propagate to the Moho. We conclude that some dikes with vertical lengths near their critical lengths and relatively high solidus temperatures will stall in the mantle before reaching the Moho, and these may be returned by corner flow to depths where they can melt under hydrous conditions. Thus, a chemical signature in arc lavas suggesting partial melting of slab basalts may be partly influenced by these recycled dikes. Alternatively, dikes with lengths well above their critical lengths can easily deliver primitive magmas to the crust, particularly if the mantle wedge is relatively hot. Dike transport remains a viable primary mechanism of magma ascent in convergent tectonic settings, but the potential for less rapid mechanisms making an important contribution increases as the mantle temperature at the Moho approaches the solidus temperature of the magma.
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The rapid unloading of ice from the southeastern sector of the Greenland ice sheet between 2001 and 2006 caused an elastic uplift of similar to 35 mm at a GPS site in Kulusuk. Most of the uplift results from ice dynamic-induced volume losses on two nearby outlet glaciers. Volume loss from Helheim Glacier, calculated from sequential digital elevation models, contributes about similar to 16 mm of the observed uplift, with an additional similar to 5 mm from volume loss of Kangerdlugssuaq Glacier. The remaining uplift signal is attributed to significant melt-induced ice volume loss from the ice sheet margin along the southeast coast between 62 degrees N and 66 degrees N.