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1.
Nanotechnology ; 34(20)2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36745915

RESUMO

We introduce a facile route for the top-down fabrication of ordered arrays of GaN nanowires with aspect ratios exceeding 10 and diameters below 20 nm. Highly uniform thin GaN nanowires are first obtained by lithographic patterning a bilayer Ni/SiNxhard mask, followed by a combination of dry and wet etching in KOH. The SiNxis found to work as an etch stop during wet etching, which eases reproducibility. Arrays with nanowire diameters down to (33 ± 5) nm can be achieved with a uniformity suitable for photonic applications. Next, a scheme for digital etching is demonstrated to further reduce the nanowire diameter down to 5 nm. However, nanowire breaking or bundling is observed for diameters below ≈20 nm, an effect that is associated to capillary forces acting on the nanowires during sample drying in air. Explicit calculations of the nanowire buckling states under capillary forces indicate that nanowire breaking is favored by the incomplete wetting of water on the substrate surface during drying. The observation of intense nanowire photoluminescence at room-temperature indicates good compatibility of the fabrication route with optoelectronic applications. The process can be principally applied to any GaN/SiNxnanostructures and allows regrowth after removal of the SiNxmask.

2.
Pharmacopsychiatry ; 49(2): 76-8, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26797932

RESUMO

In this article a case of carbamazepine overdose is reported. It is common to use immuno-based methods in the field of therapeutic drug monitoring but it might be difficult to adapt such values to toxicological cases. For carbamazepine overdoses it is recommended also to determine the metabolite carbamazepine-10,11-epoxide. Especially for critical conditions a definite substance identification should be performed. In addition, quantifying main metabolites is recommended for an acute clinical toxicological assessment.


Assuntos
Carbamazepina/administração & dosagem , Carbamazepina/farmacocinética , Monitoramento de Medicamentos/métodos , Overdose de Drogas/sangue , Carbamazepina/análogos & derivados , Carbamazepina/sangue , Carbamazepina/metabolismo , Carvão Vegetal/uso terapêutico , Overdose de Drogas/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade
3.
Scand J Med Sci Sports ; 26(7): 794-801, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26271769

RESUMO

Light has a stimulating effect on physical performance if scheduled according to the chronotype, but dose-dependent effects on performance have not yet been examined. Three groups of healthy men (25.1 ± 3.1 years) were exposed to light for different durations in a parallel group design before a 40-min time-trial. In each group, subjects were exposed to either bright light (BL, 4420 lx) or moderate light (ML, 230 lx) in a randomized order in a crossover design. The durations of light exposure were 120 min prior to and during exercise (2HEX; n = 16), 60 min prior to and during exercise (1HEX; n = 10), or only for 60 min prior to exercise (1H; n = 15). Total work performed during the time-trial in kJ in the 2HEX group was significantly higher in the BL setting (527 kJ) than in ML (512 kJ) (P = 0.002), but not in 1HEX (BL: 485 kJ; ML: 498 kJ) or 1H (BL: 519 kJ; ML: 514 kJ) (P = 0.770; P = 0.485). There was a significant (P = 0.006) positive dose-response relationship between the duration of light exposure and the work performed over the three doses of light exposure. A long duration light exposure is an effective tool to increase total work in a medium length time-trial in subjects normalized for their individual chronotype.


Assuntos
Desempenho Atlético , Ciclismo/fisiologia , Luz , Adulto , Ritmo Circadiano , Estudos Cross-Over , Feminino , Humanos , Masculino , Fatores de Tempo , Adulto Jovem
4.
Fortschr Neurol Psychiatr ; 84(S 02): S88-S91, 2016 Oct.
Artigo em Alemão | MEDLINE | ID: mdl-27806422

RESUMO

The results of laboratory tests for antineuronal antibodies in immune-mediated encephalitis nowadays are not only relevant for diagnostic purposes but are instead closely connected to outcome measures and treatment response. Besides the mere detection of antibodies, investigating the cerebrospinal fluid is indispensible to rule out an infectious etiology of encephalitis prior to the initiation of immunosuppressive treatment, whereas imaging studies are relevant to gain information on the temporal course of disease and for ruling out other etiologies, e. g. hippocampal gliomas. This work gives an overview on the clinical course and findings of laboratory, electroencephalography (EEG) and imaging studies in relevant types of autoimmune mediated encephalitis. Furthermore, it gives a synopsis on contemporary treatment strategies.


Assuntos
Doenças Autoimunes/imunologia , Doenças Autoimunes/terapia , Encefalomielite/imunologia , Encefalomielite/terapia , Autoanticorpos/imunologia , Doenças Autoimunes/diagnóstico , Eletroencefalografia , Encefalomielite/diagnóstico , Humanos
5.
Scand J Med Sci Sports ; 23(2): 156-63, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21812823

RESUMO

Laboratory, psychological and performance parameters as possible indicators of physical strain and overload during highly demanding competition phases were evaluated in elite male football players. In two studies with the same objective, periods of high (HE: >270 min during 3 weeks before testing) and low (LE: <270 min) match exposure were compared over the course of an entire season. In study 1 (n=88 players of the first and second German leagues; age: 25.6 ± 4.3 years; body mass index (BMI): 23.2 ± 1.0 kg/m(2) ), blood count, CK, urea, uric acid, CRP and ferritin were determined. In study 2, 19 players of the third German league and the highest under-19 league (age: 19.7 ± 2.8 years; BMI: 22.8 ± 1.7 kg/m(2) ) were screened for individual vertical jump height, maximal velocity and by the Recovery-Stress-Questionnaire for Athletes (REST-Q Sport). The mean differences in exposure times were 180 min (study 1: quartiles: 105, 270 min) and 247 min (study 2: 180, 347 min), respectively. Significant differences were found neither in blood parameters (study 1; P>0.36) nor in physiological testing results or in REST-Q scores (study 2; P>0.20). A 3-week period of high match exposure in elite football players does not affect laboratory, psychometric and performance parameters.


Assuntos
Atletas , Futebol/fisiologia , Estresse Fisiológico/fisiologia , Adulto , Atletas/psicologia , Contagem de Células Sanguíneas , Proteína C-Reativa/análise , Creatina Quinase/sangue , Teste de Esforço , Ferritinas/sangue , Humanos , Masculino , Resistência Física/fisiologia , Aptidão Física/fisiologia , Recuperação de Função Fisiológica/fisiologia , Inquéritos e Questionários , Ureia/sangue , Ácido Úrico/sangue
6.
Sci Rep ; 13(1): 22620, 2023 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-38114558

RESUMO

Actin beta-like 2 (ACTBL2) was recently identified as a new mediator of migration in ovarian cancer cells. Yet, its impact on tumor-infiltrating and thus migrating leukocytes (TILs) remains to date unknown. This study characterizes the subset of ACTBL2-expressing TILs in epithelial ovarian cancer (EOC) and elucidates their prognostic influence on the overall survival of EOC patients with special regard to different histological subtypes. Comprehensive immunohistochemical analyses of Tissue-Microarrays of 156 ovarian cancer patients revealed, that a tumor infiltration by ACTBL2-positive leukocytes was significantly associated with an improved overall survival (OS) (61.2 vs. 34.4 months; p = 0.006) and was identified as an independent prognostic factor (HR = 0.556; p = 0.038). This significant survival benefit was particularly evident in patients with low-grade serous carcinoma (OS: median not reached vs. 15.6 months, p < 0.001; HR = 0.058, p = 0.018). In the present cohort, ACTBL2-positive TILs were mainly composed of CD44-positive cytotoxic T-cells (CD8+) and macrophages (CD68+), as depicted by double-immunofluorescence and various immunohistochemical serial staining. Our results provide significant evidence of the prognostic impact and cellular composition of ACTBL2-expressing TILs in EOC. Complementary studies are required to analyze the underlying molecular mechanisms of ACTBL2 as a marker for activated migrating leukocytes and to further characterize its immunological impact on ovarian carcinogenesis.


Assuntos
Neoplasias Ovarianas , Humanos , Feminino , Carcinoma Epitelial do Ovário , Prognóstico , Neoplasias Ovarianas/patologia , Linfócitos T Citotóxicos/patologia , Linfócitos do Interstício Tumoral , Leucócitos/patologia
7.
Int J Sports Med ; 32(11): 875-81, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22020850

RESUMO

UNLABELLED: Often blood screening is repeatedly done in elite athletes although training and competition can affect its results and normal ranges for highly active individuals are widely unknown. This study was conducted to provide reference data in professional soccer players. 467 male soccer players of the 2 highest German leagues were observed over an entire season. Venous blood sampling was conducted 4 times in a standardized manner to determine complete blood count, AST, ALT, CK, creatinine, urea, uric acid, cholesterol, electrolytes, ferritin, CRP and TSH.There were significant changes during the season in hematocrit, creatinine, uric acid (decrease), CK, AST, urea, sodium, potassium, magnesium, and TSH (increase). Only the changes in hematocrit and CK were large enough to possibly interfere with clinical decisions in soccer players. Upper limits of the 95% confidence intervals exceeded population reference ranges slightly in AST, urea, creatinine, and potassium. The mean intraindividual coefficient of variation was below 10% in complete blood count (except leukocytes), creatinine, uric acid, total cholesterol, and all electrolytes. There seems to be a profound effect of elite soccer training and competition on hematocrit (plasma volume) and CK only. Spontaneous variability of most parameters is too small to justify repeated sampling only for routine screening. TRIAL REGISTRATION: NCT00946855 Effect of Elite Soccer Training on Routine Laboratory Parameters (SOCCERLAB), http://www.clinicaltrials.gov/ct2/show/NCT00946855?term=soccerlab&rank=1.


Assuntos
Atletas , Testes Hematológicos/métodos , Futebol/fisiologia , Adulto , Creatina Quinase/sangue , Alemanha , Hematócrito/métodos , Humanos , Masculino , Programas de Rastreamento/métodos , Valores de Referência , Adulto Jovem
8.
Poult Sci ; 90(10): 2169-73, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21933997

RESUMO

The breeding of male layer chickens is currently considered to be highly uneconomical. In Germany alone, 40 to 50 million newly hatched male chickens were killed annually immediately after hatching. Therefore, it is necessary to find a method for sexing chickens early in the embryonic development, preferably before incubation. The genotypic sex of an egg can be determined using information found in the germinal disc, so knowledge of the exact position of the germinal disc is essential for further sexing, or for other actions such as the in ovo injection of agents. Previous studies have shown that the germinal disc is located somewhere on top of the yolk. However, no studies have yet been performed that investigate the influence of time spent in horizontal storage on the position of the germinal disc. Magnetic resonance imaging was chosen to determine this influence on the position of the germinal disc. It was found that eggs placed horizontally for long periods of time before scanning had significant changes in the positions of their germinal discs compared with those of eggs scanned minutes after positioning. The position of the germinal disc in eggs, minutes after horizontal positioning, deviated 14.7 ± 0.6 mm from the maximum vertical plane of the egg (zero position) in the z-direction; eggs scanned after 96 h of horizontal positioning showed a deviation of only 4.9 ± 1.6 mm. The x-axis also exhibited changes in the position of the germinal disc over time. Immediately after horizontal positioning, the eggs showed a deviation of 0.4 ± 0.4 mm in the x-direction, whereas the deviation after 96 h was 2.9 ± 0.5 mm. These results show that horizontal positioning of the egg hours before the measurement is necessary.


Assuntos
Blastodisco/anatomia & histologia , Embrião de Galinha/anatomia & histologia , Animais , Blastodisco/química , Cruzamento , Feminino , Imageamento por Ressonância Magnética , Masculino , Análise para Determinação do Sexo/métodos , Análise para Determinação do Sexo/veterinária , Fatores de Tempo
9.
Rev Sci Instrum ; 92(12): 123004, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34972439

RESUMO

We present the design, integration, and operation of the novel vacuum ultraviolet (VUV) beamline installed at the free-electron laser (FEL) FLASH. The VUV source is based on high-order harmonic generation (HHG) in gas and is driven by an optical laser system synchronized with the timing structure of the FEL. Ultrashort pulses in the spectral range from 10 to 40 eV are coupled with the FEL in the beamline FL26, which features a reaction microscope (REMI) permanent endstation for time-resolved studies of ultrafast dynamics in atomic and molecular targets. The connection of the high-pressure gas HHG source to the ultra-high vacuum FEL beamline requires a compact and reliable system, able to encounter the challenging vacuum requirements and coupling conditions. First commissioning results show the successful operation of the beamline, reaching a VUV focused beam size of about 20 µm at the REMI endstation. Proof-of-principle photo-electron momentum measurements in argon indicate the source capabilities for future two-color pump-probe experiments.

10.
Cell Death Differ ; 15(3): 600-12, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18188168

RESUMO

The proteasome inhibitor bortezomib, which induces cell death in various cancer cell lines including lymphatic neoplasias, has recently been approved for the treatment of relapsed multiple myeloma. Important mechanisms of proteasome inhibitor-mediated tumor cell death are the inhibition of NF-kappaB activation and induction of the terminal unfolded protein response (UPR). However, little is known about effects of bortezomib on developing and mature lymphocytes. Therefore, Balb/C mice were injected with bortezomib and lymphocyte subsets were analyzed. This treatment resulted in dramatically decreased numbers of T and B lymphocyte precursors, while mature lymphocytes were only partially affected. Thymocytes were almost depleted 3 days after a single bortezomib injection, pro-B and pre-B cells already after 2 days. Thymocytes and B cell precursors recovered within 2 weeks. The decreased numbers of developing lymphocytes were due to apoptotic cell death accompanied by strongly increased caspase 3/7 activity. Within 8 h after bortezomib injection, there was a strong induction of heat shock protein 70 and C/EBP homologous protein in bone marrow B cells, indicating endoplasmic reticulum stress and activation of the terminal UPR, respectively. Hence, induction of apoptosis by proteasome inhibition can dramatically affect lymphocyte development, a fact which has important implications for the clinical use of bortezomib, especially in situations with ongoing lymphopoiesis.


Assuntos
Apoptose , Ácidos Borônicos/farmacologia , Células Precursoras de Linfócitos B/efeitos dos fármacos , Células Precursoras de Linfócitos T/efeitos dos fármacos , Inibidores de Proteases/farmacologia , Inibidores de Proteassoma , Pirazinas/farmacologia , Animais , Subpopulações de Linfócitos B/citologia , Subpopulações de Linfócitos B/efeitos dos fármacos , Células da Medula Óssea/efeitos dos fármacos , Células da Medula Óssea/imunologia , Bortezomib , Células Cultivadas , Feminino , Contagem de Linfócitos , Tecido Linfoide/citologia , Tecido Linfoide/efeitos dos fármacos , Tecido Linfoide/imunologia , Camundongos , Camundongos Endogâmicos BALB C , NF-kappa B/metabolismo , Células Precursoras de Linfócitos B/citologia , Células Precursoras de Linfócitos T/citologia , Dobramento de Proteína , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/efeitos dos fármacos , Timo/citologia , Timo/efeitos dos fármacos , Timo/imunologia
11.
Urologe A ; 57(9): 1031-1039, 2018 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-30088025

RESUMO

Digitalization cannot be understood as an off-the-shelf product, bought as a one-time purchase in a warehouse. It rather requires a constantly developing vision, which comes with a continuous transformation process, hand in hand with strategic innovation management. Thus, digitalization means understanding the digital maturity level of an enterprise and the digital skills of the employees. Besides an investment in products, a successful digitalization process also necessitates consideration of the cost to release employees from their obligations in order to contribute to the process as well as for a dedicated and continuing staff training and education program. While digitalization in Germany is underdeveloped regarding both the national health infrastructure and the level of digitalization in hospitals, German clinics are recognizing more and more the importance of digitalization and are initiating digitalization strategies. In this regard, we can learn from our European partners, who have partially established advanced and innovative solutions. Looking into these flagship projects can help to see potentials and to identify valuable building blocks for our own strategy.


Assuntos
Atenção à Saúde , Registros Eletrônicos de Saúde , Troca de Informação em Saúde , Hospitais/tendências , Assistência ao Paciente/tendências , Registros Eletrônicos de Saúde/tendências , Previsões , Alemanha , Humanos
12.
Curr Biol ; 11(11): 822-35, 2001 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-11516643

RESUMO

BACKGROUND: Taste is an important sensory modality in most animals. In Drosophila, taste is perceived by gustatory neurons located in sensilla distributed on several different appendages throughout the body of the animal. Here we show that the gustatory receptors are encoded by a family of at least 54 genes (Gr genes), most of which are expressed exclusively in a small subset of taste sensilla located in narrowly defined regions of the fly's body. RESULTS: BLAST searches with the predicted amino acid sequences of 6 7-transmembrane-receptor genes of unknown function and 20 previously identified, putative gustatory receptor genes led to the identification of a large gene family comprising at least 54 genes. We investigated the expression of eight genes by using a Gal4 reporter gene assay and found that five of them were expressed in the gustatory system of the fly. Four genes were expressed in 1%-4% of taste sensilla, located in well-defined regions of the proboscis, the legs, or both. The fifth gene was expressed in about 20% of taste sensilla in all major gustatory organs, including the taste bristles on the anterior wing margin. Axon-tracing experiments demonstrated that neurons expressing a given Gr gene project their axons to a spatially restricted domain of the subesophageal ganglion in the fly brain. CONCLUSIONS: Our findings suggest that each taste sensillum represents a discrete, functional unit expressing at least one Gr receptor and that most Gr genes are expressed in spatially restricted domains of the gustatory system. These observations imply the potential for high taste discrimination of the Drosophila brain.


Assuntos
Proteínas de Drosophila , Drosophila/fisiologia , Genes de Insetos , Proteínas de Insetos/genética , Proteínas de Membrana/genética , Proteínas do Tecido Nervoso/genética , Receptores de Superfície Celular/genética , Órgãos dos Sentidos/fisiologia , Paladar/genética , Sequência de Aminoácidos , Animais , Células Quimiorreceptoras/química , Proteínas de Insetos/classificação , Proteínas de Membrana/classificação , Dados de Sequência Molecular , Família Multigênica , Proteínas do Tecido Nervoso/classificação , Percepção/fisiologia , Receptores de Superfície Celular/classificação , Homologia de Sequência de Aminoácidos , Distribuição Tecidual
13.
J Am Coll Cardiol ; 3(3): 690-5, 1984 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-6693641

RESUMO

A prospective study was made of 57 asymptomatic patients, 1 to 24 months after acute myocardial infarction, 17 with (Group I) and 40 without (Group II) ventricular fibrillation during the acute event. None of the 57 patients had symptomatic arrhythmias, uncontrolled heart failure or unstable angina. There was no significant difference between the two patient groups in time from acute myocardial infarction, medication used or left ventricular ejection fraction. Repetitive forms of arrhythmia (Lown grade 4) were more prevalent (29 versus 16%, not significant) during 24 hour ambulatory monitoring in patients in Group I (ventricular fibrillation group). Programmed extrastimulation was performed using 1 to 3 twice-threshold, 2 ms decremental extrastimuli delivered during right ventricular drive. Of the 17 patients in Group I, 8 had no induced arrhythmia (less than or equal to 4 extra responses), 4 had nonsustained ventricular tachycardia and 5 had sustained ventricular tachycardia (degenerating into ventricular fibrillation requiring electrical reversion in 4). None of the 40 patients in Group II had induced sustained ventricular tachycardia (p less than 0.005), although 9 had nonsustained ventricular tachycardia. Patients with ventricular fibrillation during acute myocardial infarction may have an increased risk for ventricular tachycardia or ventricular fibrillation that may be exposed by programmed electrical stimulation even when not yet clinically manifest.


Assuntos
Infarto do Miocárdio/complicações , Taquicardia/etiologia , Fibrilação Ventricular/complicações , Adulto , Idoso , Cateterismo Cardíaco , Estimulação Elétrica , Eletrofisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
14.
J Am Coll Cardiol ; 10(6): 1249-53, 1987 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-3119687

RESUMO

Ventricular fibrillation during coronary angiography with Renografin-76 (meglumine sodium diatrizoate) has been attributed to the calcium-binding additives sodium citrate and sodium ethylenediaminetetraacetic acid (EDTA), which may produce repolarization changes manifested as prolongation of the QT interval. Angiovist-370 is a newer form of meglumine sodium diatrizoate that contains calcium EDTA as its additive and thus has a decreased calcium-binding effect. Eight hundred sixteen patients were prospectively randomized to receive either Renografin-76 or Angiovist-370. Ventricular fibrillation occurred in 10 of 410 patients receiving Renografin-76 and in 0 of 406 patients given Angiovist-370 (p less than 0.0005). Clinical data were analyzed without knowledge of other data in the 10 patients treated with Renografin-76 who had ventricular fibrillation (Group I), 103 randomly selected patients who also received Renografin-76 but had no ventricular fibrillation (Group II) and 108 randomly selected patients given Angiovist-370 (Group III). Of several variables examined, only the QT interval differentiated patients receiving Renografin-76 and Angiovist-370. The mean corrected QT interval (QTc interval) before coronary angiography was slightly but not significantly (p = 0.7) higher in Group I than in Groups II and III. Ten seconds after the first left coronary artery injection it was more prolonged in Groups I and II (0.552 and 0.561 second, respectively) than in Group III (0.448 second) (p less than 0.00005). Similarly, 10 seconds after the first right coronary artery injection it was significantly longer in Groups I and II (0.545 and 0.544 second) than in Group III (0.477 second) (p less than 0.00005).(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Cálcio/metabolismo , Citratos/efeitos adversos , Angiografia Coronária , Diatrizoato de Meglumina/efeitos adversos , Diatrizoato/efeitos adversos , Ácido Edético/efeitos adversos , Fibrilação Ventricular/induzido quimicamente , Citratos/farmacologia , Ácido Cítrico , Combinação de Medicamentos/efeitos adversos , Ácido Edético/farmacologia , Eletrocardiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Distribuição Aleatória , Fibrilação Ventricular/fisiopatologia
15.
Dalton Trans ; 44(14): 6466-72, 2015 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-25749307

RESUMO

A trimetallic Ir(iii) based complex () was synthesized and fully characterized by spectroscopic and electrochemical methods. A detailed comparison to its mono- () and bimetallic () analogue regarding the photocatalytic reduction of CO2 is outlined. In particular, the effect of intramolecular quenching, provided by ethyl tethers, was investigated. Moreover, the relationship between the photophysical properties, the lifetime of the excited state, the quenching efficiency and the catalytic performance is presented. Notably, the covalent linkage of the Ir(iii) moieties within the three-armed ligand structure (complex ) leads to a twofold increase of the turn over number (TON) compared to its monometallic analogue . Taking in account the quantum efficiency of 10% and the TONCO = 60 (per Ir(iii) center), complex is a highly active Ir(iii) based photocatalyst.

16.
ACS Appl Mater Interfaces ; 7(15): 7979-86, 2015 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-25719416

RESUMO

Transition metal chalcogenides with lamellar structure are known for their use in tribological applications although limited to vacuum due to their easy degradation in the presence of oxygen and/or moisture. Here we present a tailored WSex coating with low friction (0.07) and low wear rates (3×10(-7) mm3 Nm(-1)) even in ambient air. To understand the low friction behavior and lower chemical reactivity a tribological study is carried out in a high-vacuum tribometer under variable pressure (atmospheric pressure to 1×10(-8) mbar). A detailed investigation of the film nanostructure and composition by advanced transmission electron microscopy techniques with nanoscale resolution determined that the topmost layer is formed by nanocrystals of WSe2 embedded in an amorphous matrix richer in W, a-W(Se). After the friction test, an increased crystalline order and orientation of WSe2 lamellas along the sliding direction were observed in the interfacial region. On the basis of high angle annular dark field, scanning transmission electron microscopy, and energy dispersive X-ray analysis, the release of W atoms from the interstitial basal planes of the a-W(Se) phase is proposed. These W atoms reaching the surface, play a sacrificial role preventing the lubricant WSe2 phase from oxidation. The increase of the WSe2 crystalline order and the buffer effect of W capturing oxygen atoms would explain the enhanced chemical and tribological response of this designed nanocomposite material.

17.
Clin Pharmacol Ther ; 19(5 Pt 1): 515-22, 1976 May.
Artigo em Inglês | MEDLINE | ID: mdl-1277706

RESUMO

The effect of clinical doses of lidocaine on ventricular refractoriness was investigated in man. Effective refractory period (ERP) and functional refractory period (FRP) were determined in 11 normokalemic patients via a catheter at the right ventricular apex using programmed extra-stimuli and a ventricular electrogram recorded from the pacing catheter. No subject had recent ischemia or infarction. Measurements were repeated after clinical doses of lidocaine that produced therapeutic blood levels. Lidocaine caused no significant change in ERP or FRP during ventricular or atrial drive, or sinus rhythm with unchanged cycle length (CL). During sinus rhythm ERP/CL was unchanged. In 4 of 5 patients, lidocaine did not abolish echo phenomena observed during ventricular drive. This study demonstrates that ventricular refractoriness can be safely measured in man. Clinical doses of lidocaine did not alter right ventricular refractory periods. Lidocaine action is not explained by alteration of ventricular refractoriness, at least in muscle remote from the site of acute infarction.


Assuntos
Ventrículos do Coração/efeitos dos fármacos , Lidocaína/farmacologia , Idoso , Eletrocardiografia , Feminino , Humanos , Lidocaína/sangue , Masculino , Microeletrodos , Pessoa de Meia-Idade , Marca-Passo Artificial , Período Refratário Eletrofisiológico/efeitos dos fármacos
18.
Clin Pharmacol Ther ; 24(3): 274-82, 1978 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-688720

RESUMO

Ventricular extrastimulation was performed in 11 patients evaluated for chronic recurrent ventricular tachycardia, before and after a 1-gm procainamide infusion. Extrastimulation caused only nonsustained extra beats (less than 4) in 3 patients. Sustained tachycardia was induced in 7 patients in the basal state, of which 6 continued to have inducible tachycardia after procainamide was given (5.2 to 9.8 mg/L). The zone of coupling intervals that initiated tachycardia was unchanged or widened in these 6 patients because ventricular refractoriness was unchanged or because the tachycardia zone shifted to later diastole by an interval at least equivalent to the prolongation of ventricular refractoriness. Post-procainamide tachycardia cycle length was prolonged in all patients, by an average 51 msec. The one patient who responded to procainamide had a shortened ventricular refractory period, but the greatest slowing of tachycardia. Finally, sustained ventricular tachycardia could be induced in the eleventh patient only following procainamide administration, consistent with his clinical history. These results suggest that procainamide often may be ineffective in preventing sustained ventricular tachycardia, and that slowed conduction, rather than prolonged refractoriness, is the basis for the procainamide antiarrhythmic effect. Our data emphasize that antiarrhythmic drug effectiveness be evaluated in terms of effect on sustained arrhythmia rather than suppression of isolated ectopic beats.


Assuntos
Procainamida/uso terapêutico , Taquicardia/tratamento farmacológico , Idoso , Estimulação Cardíaca Artificial , Eletrocardiografia , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Período Refratário Eletrofisiológico/efeitos dos fármacos , Taquicardia/fisiopatologia , Fatores de Tempo
19.
Am J Cardiol ; 46(6): 1033-8, 1980 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-7446417

RESUMO

Fifteen consecutive patients with coronary artery disease had rapid (158 to 272 beats/min) and sustained ventricular tachycardia induced by the extrastimulus technique, and received procainamide infusion. Before the study, all but one patient had severe symptoms with tachycardia, and six had survived apparent sudden death. Procainamide consistently slowed ventricular tachycardia. However, in traditional doses (1 g infusion, plasma concentration greater than 4 micrograms/ml), it prevented induction of ventricular tachycardia in only 2 of the 15 patients. Induction of ventricular tachycardia was facilitated by procainamide in 10 patients. Larger doses of procainamide (plasma concentration 20.2 micrograms/ml +/- 9.7 [mean +/- standard deviation]) prevented induction of ventricular tachycardia in one of eight patients. Rapid ventricular rates (more than 210 beats/min) that were not slowed (by 50 percent or more) after a 1 g infusion of the drug predicted failure of procainamide to prevent ventricular tachycardia. Therefore, procainamide slowed but did not prevent induced ventricular tachycardia in most of these patients with coronary artery disease at risk of sudden death.


Assuntos
Doença das Coronárias/tratamento farmacológico , Procainamida/uso terapêutico , Taquicardia/tratamento farmacológico , Adulto , Idoso , Antiarrítmicos , Doença das Coronárias/complicações , Feminino , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia , Taquicardia/complicações
20.
Am J Cardiol ; 56(7): 403-6, 1985 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-4036819

RESUMO

Recent studies have shown that pain at rest in patients with unstable angina pectoris is often caused by transient reduction in regional myocardial perfusion. Coronary spasm has been implicated as a mechanism of this phenomenon. Recent reports have documented the occurrence of intracoronary thrombus in patients with unstable angina. Previous surveys have estimated a 6 to 12% frequency of intracoronary thrombus in this syndrome, but have not examined whether this incidence is related to how recent the angina at rest was. Angiograms of 119 patients with unstable angina who had rest pain within 14 days of angiography and 35 patients with stable angina were surveyed. Patients with unstable angina were subgrouped according to how recent angina at rest was at the time of angiography. Group I consisted of 44 patients in whom rest pain occurred within 24 hours before angiography. The 75 patients in group II had angina at rest between 1 and 14 days before angiography. Patients in group II had stable angina. The angiographic criterion for intracoronary thrombus was an intraluminal filling defect, surrounded by contrast medium on 3 sides, located just distal to or within a coronary stenosis, as assessed by each of 2 independent observers blinded to the nature of the anginal syndrome and its temporal proximity. Intracoronary thrombi were found in 44 of 119 patients with unstable angina (37%) and 0 of 35 patients with stable angina (p less than 0.00002). Intracoronary thrombi were found in 23 of 44 patients (52%) in group I and 21 of 75 (28%) in group II (p less than 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Angina Pectoris/diagnóstico por imagem , Angiografia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Descanso
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