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The January 2022 Hunga Tonga-Hunga Ha'apai eruption was one of the most explosive volcanic events of the modern era1,2, producing a vertical plume that peaked more than 50 km above the Earth3. The initial explosion and subsequent plume triggered atmospheric waves that propagated around the world multiple times4. A global-scale wave response of this magnitude from a single source has not previously been observed. Here we show the details of this response, using a comprehensive set of satellite and ground-based observations to quantify it from surface to ionosphere. A broad spectrum of waves was triggered by the initial explosion, including Lamb waves5,6 propagating at phase speeds of 318.2 ± 6 m s-1 at surface level and between 308 ± 5 to 319 ± 4 m s-1 in the stratosphere, and gravity waves7 propagating at 238 ± 3 to 269 ± 3 m s-1 in the stratosphere. Gravity waves at sub-ionospheric heights have not previously been observed propagating at this speed or over the whole Earth from a single source8,9. Latent heat release from the plume remained the most significant individual gravity wave source worldwide for more than 12 h, producing circular wavefronts visible across the Pacific basin in satellite observations. A single source dominating such a large region is also unique in the observational record. The Hunga Tonga eruption represents a key natural experiment in how the atmosphere responds to a sudden point-source-driven state change, which will be of use for improving weather and climate models.
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For many chemical reactions, it remains notoriously difficult to predict and experimentally determine the rates and branching ratios between different reaction channels. This is particularly the case for reactions involving short-lived intermediates, whose observation requires ultrafast methods. The UV photochemistry of bromoform (CHBr3) is among the most intensely studied photoreactions. Yet, a detailed understanding of the chemical pathways leading to the production of atomic Br and molecular Br2 fragments has proven challenging. In particular, the role of isomerization and/or roaming and their competition with direct C-Br bond scission has been a matter of continued debate. Here, gas-phase ultrafast megaelectronvolt electron diffraction (MeV-UED) is used to directly study structural dynamics in bromoform after single 267 nm photon excitation with femtosecond temporal resolution. The results show unambiguously that isomerization contributes significantly to the early stages of the UV photochemistry of bromoform. In addition to direct C-Br bond breaking within <200 fs, formation of iso-CHBr3 (Br-CH-Br-Br) is observed on the same time scale and with an isomer lifetime of >1.1 ps. The branching ratio between direct dissociation and isomerization is determined to be 0.4 ± 0.2:0.6 ± 0.2, i.e., approximately 60% of molecules undergo isomerization within the first few hundred femtoseconds after UV excitation. The structure and time of formation of iso-CHBr3 compare favorably with the results of an ab initio molecular dynamics simulation. The lifetime and interatomic distances of the isomer are consistent with the involvement of a roaming reaction mechanism.
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Ice XIX and ice XV are both partly hydrogen-ordered counterparts to disordered ice VI. The ice XIX â XV transition represents the only order-to-order transition in ice physics. Using Raman and dielectric spectroscopies, we investigate the ambient-pressure kinetics of the two individual steps in this transition in real time (of hours), that is, ice XIX â transient ice VI (the latter called VI) and ice VI â ice XV. Hydrogen-disordered ice VI appears intermittent between 101 and 120 K, as inferred from the appearance and subsequent disappearance of the ice VI Raman marker bands. A comparison of the rate constants for the H2O ices reported here with those from D2O samples [Thoeny et al., J. Chem. Phys. 156, 154507 (2022)] reveals a large kinetic isotope effect for the ice XIX decay, but a much smaller one for the ice XV buildup. An enhancement of the classical overbarrier rate through quantum tunneling for the former can provide a possible explanation for this finding. The activation barriers for both transitions are in the 18-24 kJ/mol range, which corresponds to the energy required to break a single hydrogen bond. These barriers do not show an H/D isotope effect and are the same, no matter whether they are derived from Raman scattering or from dielectric spectroscopy. These findings favor the notion that a dipolar reorientation, involving the breakage of a hydrogen bond, is the rate determining step at the order-to-order transition.
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Solvated in propylene carbonate, viscous phenol is studied using dielectric spectroscopy and shear rheology. In addition, several oxygen-17 and deuteron nuclear magnetic resonance (NMR) techniques are applied to specifically isotope labeled equimolar mixtures. Quantum chemical calculations are used to check the electrical field gradient at phenol's oxygen site. The chosen combination of NMR methods facilitates the selective examination of potentially hydrogen-bond related contributions as well as those dominated by the structural relaxation. Taken together the present results for phenol in equimolar mixtures with the van der Waals liquid propylene carbonate provide evidence for the existence of a very weak Debye-like process that originates from ringlike supramolecular associates.
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Using oxygen-17 as a nuclear probe, spin relaxometry was applied to study the high-density and low-density states of amorphous ice, covering temperatures below and somewhat above their glass transitions. These findings are put in perspective with results from deuteron nuclear magnetic resonance and with calculations based on dielectrically detected correlation times. This comparison reveals the presence of a wide distribution of correlation times. Furthermore, oxygen-17 central-transition echo spectra were recorded for wide ranges of temperature and pulse spacing. The spectra cannot be described by a single set of quadrupolar parameters, suggesting a distribution of H-O-H opening angles that is broader for high-density than for low-density amorphous ice. Simulations of the pulse separation dependent spin-echo spectra for various scenarios demonstrate that a small-step frequency diffusion process, assigned to the presence of homonuclear oxygen-oxygen interactions, determines the shape evolution of the pulse-separation-dependent spectra.
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In this work, trimethoxyboroxine (TMB) is identified as a small-molecule glass former. In its viscous liquid as well as glassy states, static and dynamic properties of TMB are explored using various techniques. It is found that, on average, the structure of the condensed TMB molecules deviates from threefold symmetry so that TMB's electric dipole moment is nonzero, thus rendering broadband dielectric spectroscopy applicable. This method reveals the super-Arrhenius dynamics that characterizes TMB above its glass transition, which occurs at about 204 K. To extend the temperature range in which the molecular dynamics can be studied, 11B nuclear magnetic resonance experiments are additionally carried out on rotating and stationary samples: Exploiting dynamic second-order shifts, spin-relaxation times, line shape effects, as well as stimulated-echo and two-dimensional exchange spectroscopy, a coherent picture regarding the dynamics of this glass former is gained.
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To characterize the structural relaxation of an aqueous solution of LiCl, frequency-dependent shear rheological experiments are carried out near its glass transition. Analyzed within the fluidity representation, the generic spectral shape that was previously found for a range of different kinds of glass formers is confirmed for the currently studied hydrogen-bonded fluid as well. Furthermore, the validity of the rheological equivalent of the Barton-Nakajima-Namikawa relation is demonstrated for the aqueous LiCl solution. Its mechanical response is compared with that obtained using dielectric spectroscopy, a technique which is sensitive to both the reorientational dynamics of the water molecules and the translational dynamics of the ionic species. The extent to which these electrical polarization processes are coupled to those governing the viscoelastic response is discussed, also in comparison with the behavior of other ion conducting liquids.
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Gravity waves (disturbances to the density structure of the atmosphere whose restoring forces are gravity and buoyancy) comprise the principal form of energy exchange between the lower and upper atmosphere. Wave breaking drives the mean upper atmospheric circulation, determining boundary conditions to stratospheric processes, which in turn influence tropospheric weather and climate patterns on various spatial and temporal scales. Despite their recognized importance, very little is known about upper-level gravity wave characteristics. The knowledge gap is mainly due to lack of global, high-resolution observations from currently available satellite observing systems. Consequently, representations of wave-related processes in global models are crude, highly parameterized, and poorly constrained, limiting the description of various processes influenced by them. Here we highlight, through a series of examples, the unanticipated ability of the Day/Night Band (DNB) on the NOAA/NASA Suomi National Polar-orbiting Partnership environmental satellite to resolve gravity structures near the mesopause via nightglow emissions at unprecedented subkilometric detail. On moonless nights, the Day/Night Band observations provide all-weather viewing of waves as they modulate the nightglow layer located near the mesopause (â¼ 90 km above mean sea level). These waves are launched by a variety of physical mechanisms, ranging from orography to convection, intensifying fronts, and even seismic and volcanic events. Cross-referencing the Day/Night Band imagery with conventional thermal infrared imagery also available helps to discern nightglow structures and in some cases to attribute their sources. The capability stands to advance our basic understanding of a critical yet poorly constrained driver of the atmospheric circulation.
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Betaine critically contributes to the control of hepatocellular hydration and provides protection of the liver from different kinds of stress. To investigate how the hepatocellular hydration state affects gene expression of enzymes involved in the metabolism of betaine and related organic osmolytes, we used quantitative RT-PCR gene expression studies in rat hepatoma cells as well as metabolic and gene expression profiling in primary hepatocytes of both wild-type and 5,10-methylenetetrahydrofolate reductase (MTHFR)-deficient mice. Anisotonic incubation caused coordinated adaptive changes in the expression of various genes involved in betaine metabolism, in particular of betaine homocysteine methyltransferase, dimethylglycine dehydrogenase, and sarcosine dehydrogenase. The expression of betaine-degrading enzymes was downregulated by cell shrinking and strongly induced by an increase in cell volume under hypotonic conditions. Metabolite concentrations in the culture system changed accordingly. Expression changes were mediated through tyrosine kinases, cyclic nucleotide-dependent protein kinases, and JNK-dependent signaling. Assessment of hepatic gene expression using a customized microarray chip showed that hepatic betaine depletion in MTHFR(-/-) mice was associated with alterations that were comparable to those induced by cell swelling in hepatocytes. In conclusion, the adaptation of hepatocytes to changes in cell volume involves the coordinated regulation of betaine synthesis and degradation and concomitant changes in intracellular osmolyte concentrations. The existence of such a well-orchestrated response underlines the importance of cell volume homeostasis for liver function and of methylamine osmolytes such as betaine as hepatic osmolytes.
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Betaína-Homocisteína S-Metiltransferase/metabolismo , Betaína/metabolismo , Dimetilglicina Desidrogenase/metabolismo , Fígado/metabolismo , Concentração Osmolar , Sarcosina Desidrogenase/metabolismo , Animais , Tamanho Celular/efeitos dos fármacos , Neoplasias Hepáticas Experimentais , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , Camundongos , Camundongos Transgênicos , Osmose , RNA Mensageiro/metabolismo , Ratos , Transcriptoma , Células Tumorais CultivadasRESUMO
Tandem mass spectrometry-based newborn screening correctly identifies individuals with very long-chain acyl-CoA dehydrogenase deficiency (VLCADD). However, a great number of healthy individuals present with identical acylcarnitine profiles during catabolism in the first three days of life. We routinely perform an enzyme activity assay as confirmation analysis in newborns identified by screening. Whereas VLCAD residual activities of less than 10% are clearly diagnostic and indicate patients at risk of clinical disease, the clinical relevance of higher residual activities is unclear. In this study we assess the molecular basis in 34 individuals with residual activities of 10-50%. We identify two pathogenic mutations in patients that result in residual activities as high as 22%, while individuals with residual activities of 25-50% either present with a heterozygous or no mutation in the VLCAD gene. In addition, confirmed heterozygous parents present with residual activities as low as 32%.In conclusion, we identify individuals with 2 pathogenic mutations and those with only one heterozygous mutation in the residual activity range of 20-30%. Whereas heterozygosity is generally regarded as clinically irrelevant, identification of 2 VLCAD mutations leads to precautions in the management of the children. Based on our data we anticipate that individuals with a residual enzyme activity >20% present with a biochemical phenotype but likely remain asymptomatic throughout life. Studies in greater patient numbers are needed to correlate residual activities >10% with the genotype and the outcome.
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Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Acil-CoA Desidrogenase de Cadeia Longa/metabolismo , Erros Inatos do Metabolismo Lipídico/enzimologia , Doenças Mitocondriais/enzimologia , Doenças Musculares/enzimologia , Acil-CoA Desidrogenase de Cadeia Longa/genética , Síndrome Congênita de Insuficiência da Medula Óssea , Genótipo , Heterozigoto , Humanos , Recém-Nascido , Erros Inatos do Metabolismo Lipídico/genética , Doenças Mitocondriais/genética , Doenças Musculares/genética , Mutação , Triagem Neonatal/métodos , Fenótipo , Medição de RiscoRESUMO
BACKGROUND: Personalised feedback constitutes an important component of E- and M-mental health applications (E = electronic and M = mobile computing and communication technologies) for disease prevention and management. It can be used to increase motivation, highlight risks, change attitudes and counterbalance the lack of personal contact in computerised health interventions. Research suggests that compared with targeted or generic feedback, personalised feedback is a more effective intervention component. AIMS: To discuss challenges and options for the generation and delivery of personalised feedback in E- and M-mental health interventions. Suggestions for the development of normative, summative and ipsative feedback are provided. RESULTS: We demonstrate how information from (multiple) assessments and/or data from comparable samples can be integrated into statistically supported and user-friendly feedback without including test scores. CONCLUSION: Proposals made in this paper need to be the subject of empirical studies and should be tested in terms of their feasibility, acceptability and efficacy.
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Retroalimentação , Serviços de Saúde Mental , Telemedicina/métodos , Terapia Assistida por Computador/métodos , Humanos , Modelos Estatísticos , Valores de Referência , Reforço PsicológicoRESUMO
The interaction of intense light with matter gives rise to competing nonlinear responses that can dynamically change material properties. Prominent examples are saturable absorption (SA) and two-photon absorption (TPA), which dynamically increase and decrease the transmission of a sample depending on pulse intensity, respectively. The availability of intense soft X-ray pulses from free-electron lasers (FELs) has led to observations of SA and TPA in separate experiments, leaving open questions about the possible interplay between and relative strength of the two phenomena. Here, we systematically study both phenomena in one experiment by exposing graphite films to soft X-ray FEL pulses of varying intensity. By applying real-time electronic structure calculations, we find that for lower intensities the nonlinear contribution to the absorption is dominated by SA attributed to ground-state depletion; our model suggests that TPA becomes more dominant for larger intensities (>1014 W/cm2). Our results demonstrate an approach of general utility for interpreting FEL spectroscopies.
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The lack of available table-top extreme ultraviolet (XUV) sources with high enough fluxes and coherence properties has limited the availability of nonlinear XUV and x-ray spectroscopies to free-electron lasers (FELs). Here, we demonstrate second harmonic generation (SHG) on a table-top XUV source by observing SHG near the Ti M2,3 edge with a high-harmonic seeded soft x-ray laser. Furthermore, this experiment represents the first SHG experiment in the XUV. First-principles electronic structure calculations suggest the surface specificity and separate the observed signal into its resonant and nonresonant contributions. The realization of XUV-SHG on a table-top source opens up more accessible opportunities for the study of element-specific dynamics in multicomponent systems where surface, interfacial, and bulk-phase asymmetries play a driving role.
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Dietary modification with medium-chain triglyceride (MCT) supplementation is one crucial way of treating children with long-chain fatty acid oxidation disorders. Recently, supplementation prior to exercise has been reported to prevent muscular pain and rhabdomyolysis. Systematic studies to determine when MCT supplementation is most beneficial have not yet been undertaken. We studied the effects of an MCT-based diet compared with MCT administration only prior to exercise in very-long-chain acyl-CoA dehydrogenase (VLCAD) knockout (KO) mice. VLCAD KO mice were fed an MCT-based diet in same amounts as normal mouse diet containing long-chain triglycerides (LCT) and were exercised on a treadmill. Mice fed a normal LCT diet received MCT only prior to exercise. Acylcarnitine concentration, free carnitine concentration, and acyl-coenzyme A (CoA) oxidation capacity in skeletal muscle as well as hepatic lipid accumulation were determined. Long-chain acylcarnitines significantly increased in VLCAD-deficient skeletal muscle with an MCT diet compared with an LCT diet with MCT bolus prior to exercise, whereas an MCT bolus treatment significantly decreased long-chain acylcarnitines after exercise compared with an LCT diet. C8-carnitine was significantly increased in skeletal muscle after MCT bolus treatment and exercise compared with LCT and long-term MCT treatment. Increased hepatic lipid accumulation was observed in long-term MCT-treated KO mice. MCT seems most beneficial when given in a single dose directly prior to exercise to prevent acylcarnitine accumulation. In contrast, continuous MCT treatment produces a higher skeletal muscle content of long-chain acylcarnitines after exercise and increases hepatic lipid storage in VLCAD KO mice.
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Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Acil-CoA Desidrogenase de Cadeia Longa/genética , Músculo Esquelético/metabolismo , Condicionamento Físico Animal , Triglicerídeos/metabolismo , Acil Coenzima A/metabolismo , Ração Animal , Animais , Carnitina/análogos & derivados , Carnitina/metabolismo , Lipídeos/química , Camundongos , Camundongos Knockout , Oxazinas/farmacologia , Oxigênio/químicaRESUMO
Long-chain acylcarnitines accumulate in long-chain fatty acid oxidation defects, especially during periods of increased energy demand from fat. To test whether this increase in long-chain acylcarnitines in very long-chain acyl-CoA dehydrogenase (VLCAD(-/-)) knock-out mice correlates with acyl-CoA content, we subjected wild-type (WT) and VLCAD(-/-) mice to forced treadmill running and analyzed muscle long-chain acyl-CoA and acylcarnitine with tandem mass spectrometry (MS/MS) in the same tissues. After exercise, long-chain acyl-CoA displayed a significant increase in muscle from VLCAD(-/-) mice [C16:0-CoA, C18:2-CoA and C18:1-CoA in sedentary VLCAD(-/-): 5.95 +/- 0.33, 4.48 +/- 0.51, and 7.70 +/- 0.30 nmol x g(-1) wet weight, respectively; in exercised VLCAD(-/-): 8.71 +/- 0.42, 9.03 +/- 0.93, and 14.82 +/- 1.20 nmol x g(-1) wet weight, respectively (P < 0.05)]. Increase in acyl-CoA in VLCAD-deficient muscle was paralleled by a significant increase in the corresponding chain length acylcarnitine. Exercise resulted in significant lowering of the free carnitine pool in VLCAD(-/-) muscle. This is the first study demonstrating that acylcarnitines and acyl-CoA directly correlate and concomitantly increase after exercise in VLCAD-deficient muscle.
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Acil Coenzima A/análise , Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Carnitina/análogos & derivados , Músculo Esquelético/química , Esforço Físico/fisiologia , Acil-CoA Desidrogenase de Cadeia Longa/genética , Animais , Peso Corporal , Carnitina/análise , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias Musculares/enzimologiaRESUMO
OBJECTIVE: The purpose of this study was to investigate the effects of abuse conditions, including realistic crash scenarios, on Li ion battery systems in E-vehicles in order to develop safe practices and priorities when responding to accidents involving E-vehicles. METHOD: External fire tests using a single burning item equipment were performed on commercial Li ion battery cells and battery packs for electric vehicle (E-vehicle) application. The 2 most common battery cell technologies were tested: Lithium iron phosphate (LFP) and mixed transition metal oxide (lithium nickel manganese cobalt oxide, NMC) cathodes against graphite anodes, respectively. The cell types investigated were "pouch" cells, with similar physical dimensions, but the NMC cells have double the electric capacity of the LFP cells due to the higher energy density of the NMC chemistry, 7 and 14 Ah, respectively. Heat release rate (HRR) data and concentrations of toxic gases were acquired by oxygen consumption calorimetry and Fourier transform infrared spectroscopy (FTIR), respectively. RESULTS: The test results indicate that the state of charge (SOC) affects the HRR as well as the amount of toxic hydrogen fluoride (HF) gas formed during combustion. A larger number of cells increases the amount of HF formed per cell. There are significant differences in response to the fire exposure between the NMC and LFP cells in this study. The LFP cells generate a lot more HF per cell, but the overall reactivity of the NMC cells is higher. However, the total energy released by both batteries during combustion was independent of SOC, which indicates that the electric energy content of the test object contributes to the activation energy of the thermal and heat release process, whereas the chemical energy stored in the materials is the main source of thermal energy in the batteries. CONCLUSIONS: The results imply that it is difficult to draw conclusions about higher order system behavior with respect to HF emissions based on data from tests on single cells or small assemblies of cells. This applies to energy release rates as well. The present data show that mass and shielding effects between cells in multicell assemblies affect the propagation of a thermal event.
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Fontes de Energia Elétrica , Incêndios , Cobalto , Humanos , Lítio , Manganês , Níquel , ÓxidosRESUMO
Patients with inborn errors of long-chain fatty acid oxidation accumulate disease-specific acylcarnitines and triacylglycerols in various tissues. Some of these patients present significant cardiac diseases such as arrhythmias and cardiomyopathy. The mechanism of how fatty acid accumulation is involved in disease pathogenesis is still unclear but apoptosis of cardiomyocytes has been suggested to be one possible mechanism of cardiomyopathy development. In this study, we measured lipid uptake and intracellular lipid accumulation after incubation of HL1 cardiomyocytes with different saturated and monounsaturated long- and medium-chain fatty acid species for various time periods and at different physiological concentrations. We assessed apoptosis induction by analyzing the mitochondrial membrane potential and TLR-4 expression as well as the composition of the accumulating triacylglycerols. We identified only 14:1 and 16:1 monounsaturated fatty acids potentially leading to an increase in TLR-4 expression and disruption of the mitochondrial membrane potential, resulting in apoptosis and necrosis in cultured cardiomyocytes. This study demonstrates significant toxicity of especially those fatty acid species in vitro that significantly accumulate in fatty acid oxidation defects presenting with cardiac disease such as very long-chain acyl-CoA dehydrogenase, carnitine acylcarnitine translocase and carnitine palmitoyl-CoA transferase deficiencies.
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Apoptose/efeitos dos fármacos , Ácidos Graxos Insaturados/farmacologia , Ácidos Graxos/farmacologia , Miócitos Cardíacos/efeitos dos fármacos , Acil-CoA Desidrogenase de Cadeia Longa/genética , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ácidos Graxos/metabolismo , Ácidos Graxos/toxicidade , Ácidos Graxos Insaturados/metabolismo , Ácidos Graxos Insaturados/toxicidade , Expressão Gênica/efeitos dos fármacos , L-Lactato Desidrogenase/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Microscopia de Fluorescência , Miócitos Cardíacos/metabolismo , Necrose/induzido quimicamente , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Receptor 4 Toll-Like/genética , Triglicerídeos/metabolismoRESUMO
The aim of this study was to evaluate a novel third-generation enzyme-linked immunosorbent assay (ELISA) for the high-sensitivity detection of autoantibodies to proteinase-3 (PR3) in patients with Wegener's granulomatosis (WG). First- and second-generation ELISA for the detection of antineutrophil cytoplasmic antibodies (ANCA) frequently demonstrate insufficient sensitivity due to inadequate presentation of autoantigenic epitopes. Human PR3 was immobilized on the solid phase of ELISA plates by anchoring technique. Anti-PR3 reactivity was measured in 34 C-ANCA positive patients with WG, 11 MPO-ANCA-positive patients with other autoimmune vasculitides, 65 patients with systemic lupus erythematosus (SLE), and 137 healthy blood donors. Thirty-three of 34 patients with WG (97.1%) showed positive anti-PR3 IgG antibody reactivity. None of 11 MPO-ANCA positive vasculitis patients, none of 137 blood donors, and 3 of 65 SLE patients expressed elevated IgG reactivity to PR3 (specificity: 98.4%). Comparison with another third-generation ELISA did not reveal different qualitative results. However, there was no significant correlation between quantitative results of both assays. Receiver operating characteristic (ROC) curve analysis revealed a significantly better assay performance compared with first (direct)- and second (capture)-generation assays (P = 0.011 and P = 0.001, respectively). Third-generation (anchor) anti-PR3 ELISA exhibit significantly higher sensitivity than previous generation assays. Anchoring of PR3 renders the granulocyte protein more autoantigenic compared with direct or capture immobilization.
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Autoanticorpos/sangue , Ensaio de Imunoadsorção Enzimática/métodos , Granulomatose com Poliangiite/diagnóstico , Mieloblastina/imunologia , Anticorpos Anticitoplasma de Neutrófilos/sangue , Enzimas Imobilizadas/imunologia , Humanos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Cell hydration changes critically affect liver metabolism and gene expression. In the course of gene expression studies using nylon cDNA-arrays we found that hyperosmolarity (405 mosmol/l) suppressed the betaine-homocysteine methyltransferase (Bhmt) mRNA expression in H4IIE rat hepatoma cells. This was confirmed by Northern blot and real-time quantitative RT-PCR analysis, which in addition unraveled a pronounced induction of Bhmt mRNA expression by hypoosmotic (205 mosmol/l) swelling. Osmotic regulation of Bhmt mRNA expression was largely paralleled at the levels of Bhmt protein and enzymatic activity. Like hyperosmotic NaCl, hyperosmotic raffinose but not hyperosmotic urea suppressed Bhmt mRNA expression, suggesting that cell shrinkage rather than increased ionic strength or hyperosmolarity per se is the trigger. Hypoosmolarity increased the expression of a reporter gene driven by the entire human BHMT promoter, whereas destabilization of BHMT mRNA was observed under hyperosmotic conditions. Osmosensitivity of Bhmt mRNA expression was impaired by inhibitors of tyrosine kinases and cyclic nucleotide-dependent kinases. The osmotic regulation of BHMT may be part of a cell volume-regulatory response and additionally lead to metabolic alterations that depend on the availability of betaine-derived methyl groups.
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Betaína-Homocisteína S-Metiltransferase/metabolismo , Carcinoma Hepatocelular/enzimologia , Regulação Enzimológica da Expressão Gênica , Neoplasias Hepáticas/enzimologia , Equilíbrio Hidroeletrolítico , Animais , Betaína/metabolismo , Betaína-Homocisteína S-Metiltransferase/genética , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Carcinoma Hepatocelular/fisiopatologia , Linhagem Celular Tumoral , Tamanho Celular , Proteínas Quinases Reguladas por Nucleotídeo Cíclico/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/fisiopatologia , Concentração Osmolar , Osmose , Regiões Promotoras Genéticas , Inibidores de Proteínas Quinases/farmacologia , Proteínas Tirosina Quinases/metabolismo , RNA Mensageiro/metabolismo , Rafinose/química , Rafinose/metabolismo , Ratos , Solução Salina Hipertônica/metabolismo , Sarcosina/análogos & derivados , Sarcosina/metabolismo , Transdução de Sinais , Fatores de Tempo , Transcrição Gênica , Transfecção , Ureia/química , Ureia/metabolismoRESUMO
A multimodal treatment protocol with immunoadsorption (IA) as the central element was used in the treatment of myasthenic crisis (MC). Fifteen patients with MC were treated in repeated, uninterrupted 7-day cycles until mobilization with: (i) large-volume IA using an antihuman-IgG adsorber, days 1-5; (ii) intravenous immunoglobulin substitution (0.3-0.5 g/kg body weight [BW]/day), days 5-7; and (iii) immunosuppression with cyclophosphamide (1-2 mg/kg BW/day) and prednisolone (0.5-1 mg/kg BW/day), until remission. Patients required a median of 8 days of mechanical ventilation, 12 days in the intensive care unit, and 35 days of hospitalization. Functional improvement compared to their precrisis condition was attained by 14 of 15 patients. MG severity score improved by a mean of 10 points, quality of life score by 9.8 points, and Karnofsky index by 29 points in 14 of 15 patients. Improvements remained stable and no further crises occurred during long-term follow-up, which averaged 4.4 years. No fatalities due to MC occurred. The results demonstrate that our protocol is a potent therapeutic approach in the treatment of MC.