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1.
Strahlenther Onkol ; 197(9): 836-846, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34196725

RESUMO

PURPOSE: Dose, fractionation, normalization and the dose profile inside the target volume vary substantially in pulmonary stereotactic body radiotherapy (SBRT) between different institutions and SBRT technologies. Published planning studies have shown large variations of the mean dose in planning target volume (PTV) and gross tumor volume (GTV) or internal target volume (ITV) when dose prescription is performed to the PTV covering isodose. This planning study investigated whether dose prescription to the mean dose of the ITV improves consistency in pulmonary SBRT dose distributions. MATERIALS AND METHODS: This was a multi-institutional planning study by the German Society of Radiation Oncology (DEGRO) working group Radiosurgery and Stereotactic Radiotherapy. CT images and structures of ITV, PTV and all relevant organs at risk (OAR) for two patients with early stage non-small cell lung cancer (NSCLC) were distributed to all participating institutions. Each institute created a treatment plan with the technique commonly used in the institute for lung SBRT. The specified dose fractionation was 3â€¯× 21.5 Gy normalized to the mean ITV dose. Additional dose objectives for target volumes and OAR were provided. RESULTS: In all, 52 plans from 25 institutions were included in this analysis: 8 robotic radiosurgery (RRS), 34 intensity-modulated (MOD), and 10 3D-conformal (3D) radiation therapy plans. The distribution of the mean dose in the PTV did not differ significantly between the two patients (median 56.9 Gy vs 56.6 Gy). There was only a small difference between the techniques, with RRS having the lowest mean PTV dose with a median of 55.9 Gy followed by MOD plans with 56.7 Gy and 3D plans with 57.4 Gy having the highest. For the different organs at risk no significant difference between the techniques could be found. CONCLUSIONS: This planning study pointed out that multiparameter dose prescription including normalization on the mean ITV dose in combination with detailed objectives for the PTV and ITV achieve consistent dose distributions for peripheral lung tumors in combination with an ITV concept between different delivery techniques and across institutions.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Radiocirurgia , Radioterapia de Intensidade Modulada , Carcinoma Pulmonar de Células não Pequenas/patologia , Humanos , Pulmão/patologia , Neoplasias Pulmonares/patologia , Prescrições , Radiocirurgia/métodos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos
2.
Rev Sci Instrum ; 91(6): 061101, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32611046

RESUMO

The transition from old space to new space along with increasing commercialization has a major impact on space flight, in general, and on electric propulsion (EP) by ion thrusters, in particular. Ion thrusters are nowadays used as primary propulsion systems in space. This article describes how these changes related to new space affect various aspects that are important for the development of EP systems. Starting with a historical overview of the development of space flight and of the technology of EP systems, a number of important missions with EP and the underlying technologies are presented. The focus of our discussion is the technology of the radio frequency ion thruster as a prominent member of the gridded ion engine family. Based on this discussion, we give an overview of important research topics such as the search for alternative propellants, the development of reliable neutralizer concepts based on novel insert materials, as well as promising neutralizer-free propulsion concepts. In addition, aspects of thruster modeling and requirements for test facilities are discussed. Furthermore, we address aspects of space electronics with regard to the development of highly efficient electronic components as well as aspects of electromagnetic compatibility and radiation hardness. This article concludes with a presentation of the interaction of EP systems with the spacecraft.

3.
RSC Adv ; 9(20): 11521-11529, 2019 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-35520264

RESUMO

Production and secretion of biomolecules can provide new emergent functionalities to the synthesizing organism. In particular, the secretion of extracellular polymeric substances (EPS) by biofilm forming bacteria creates a biofilm matrix that protects the individual bacteria within the biofilm from external stressors such as antibiotics, chemicals and shear flow. Although the main matrix components of biofilms formed by Bacillus subtilis are known, it remains unclear how these matrix components contribute to the erosion stability of B. subtilis biofilms. Here, we combine different biophysical techniques to assess this relation. In particular, we quantify the importance of specific biofilm matrix components on the erosion behavior of biofilms formed by the well-studied Bacillus subtilis NCIB 3610. We find that the absence of biofilm matrix components decreases the erosion stability of NCIB 3610 biofilms in water, largely by abolishing the hydrophobic surface properties of the biofilm and by reducing the biofilm stiffness. However, the erosion resistance of NCIB 3610 biofilms is strongly increased in the presence of metal ions or the antibiotic ciprofloxacin. In the first case, unspecific ionic cross-linking of biofilm components or individual bacteria seems to be responsible for the observed effect, and in the second case there seems to be an unspecific interaction between the antibiotic and the biofilm matrix. Taken together, our results emphasize the importance of the biofilm matrix to reduce biofilm erosion and give insights into how the specific biomolecules interact with certain chemicals to fulfill this task.

4.
Phys Rev E ; 97(4-1): 043203, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29758751

RESUMO

Three-dimensional plasma crystals are often described as Yukawa systems for which a phase transition between the crystal structures fcc and bcc has been predicted. However, experimental investigations of this transition are missing. We use a fast scanning video camera to record the crystallization process of 70 000 microparticles and investigate the existence of the fcc-bcc phase transition at neutral gas pressures of 30, 40, and 50 Pa. To analyze the crystal, robust phase diagrams with the help of a machine learning algorithm are calculated. This work shows that the phase transition can be investigated experimentally and makes a comparison with numerical results of Yukawa systems. The phase transition is analyzed in dependence on the screening parameter and structural order. We suggest that the transition is an effect of gravitational compression of the plasma crystal. Experimental investigations of the fcc-bcc phase transition will provide an opportunity to estimate the coupling strength Γ by comparison with numerical results of Yukawa systems.

5.
US CLIVAR Rep ; n/a2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31633127

RESUMO

The Arctic has warmed more than twice as fast as the global average since the mid 20th century, a phenomenon known as Arctic amplification (AA). These profound changes to the Arctic system have coincided with a period of ostensibly more frequent events of extreme weather across the Northern Hemisphere (NH) mid-latitudes, including extreme heat and rainfall events and recent severe winters. Though winter temperatures have generally warmed since 1960 over mid-to-high latitudes, the acceleration in the rate of warming at high-latitudes, relative to the rest of the NH, started approximately in 1990. Trends since 1990 show cooling over the NH continents, especially in Northern Eurasia. The possible link between Arctic change and mid-latitude climate and weather has spurred a rush of new observational and modeling studies. A number of workshops held during 2013-2014 have helped frame the problem and have called for continuing and enhancing efforts for improving our understanding of Arctic-mid-latitude linkages and its attribution to the occurrence of extreme climate and weather events. Although these workshops have outlined some of the major challenges and provided broad recommendations, further efforts are needed to synthesize the diversified research results to identify where community consensus and gaps exist. Building upon findings and recommendations of the previous workshops, the US CLIVAR Working Group on Arctic Change and Possible Influence on Mid-latitude Climate and Weather convened an international workshop at Georgetown University in Washington, DC, on February 1-3, 2017. Experts in the fields of atmosphere, ocean, and cryosphere sciences assembled to assess the rapidly evolving state of understanding, identify consensus on knowledge and gaps in research, and develop specific actions to accelerate progress within the research community. With more than 100 participants, the workshop was the largest and most comprehensive gathering of climate scientists to address the topic to date. In this white paper, we synthesize and discuss outcomes from this workshop and activities involving many of the working group members. Workshop findings: Rapid Arctic change - Emergence of new forcing (external and internal) of atmospheric circulation: Rapid Arctic change is evident in the observations and is simulated and projected by global climate models. AA has been attributed to sea ice and snow decline (regionally and seasonally varying). However this cannot explain why AA is greatest in winter and weakest in summer. It was argued at the workshop that other factors can also greatly contribute to AA including: increased downwelling longwave radiation from greenhouse gases (including greater water vapor concentrations from local and remote sources); increasing ocean heat content, due to local and remote processes; regional and hemispheric atmospheric circulation changes; increased poleward heat transport in the atmosphere and ocean; and cloud radiative forcing. In particular, there is emerging observational evidence that an enhanced poleward transport of sensible and latent heat plays a very important role in the AA of the recent decades, and that this enhancement is mostly fueled by changes in the atmospheric circulation. We concluded that our understanding of AA is incomplete, especially the relative contributions from the different radiative, thermodynamic, and dynamic processes.Arctic mid-latitude linkages - Focusing on seasonal and regional linkages and addressing sources of inconsistency and uncertainty among studies: The topic of Arctic mid-latitude linkages is controversial and was vigorously debated at the workshop. However, we concluded that rapid Arctic change is contributing to changes in mid-latitude climate and weather, as well as the occurrence of extreme events. But how significant the contribution is and what mechanisms are responsible are less well understood. Based on the synthesis efforts of observational and modeling studies, we identified a list of proposed physical processes or mechanisms that may play important roles in linking Arctic change to mid-latitude climate and weather. The list, ordered from high to low confidence, includes: increasing geopotential thickness over the polar cap; weakening of the thermal wind; modulating stratosphere-troposphere coupling; exciting anomalous planetary waves or stationary Rossby wave trains in winter and modulating transient synoptic waves in summer; altering storm tracks and behavior of blockings; and increasing frequency of occurrence of summer wave resonance. The pathway considered most robust is the propagation of planetary/Rossby waves excited by the diminished Barents-Kara sea ice, contributing to a northwestward expansion and intensification of the Siberian high leading to cold Eurasian winters. Opportunities and recommendations: An important goal of the workshop was achieved: to hasten progress towards consensus understanding and identification of knowledge gaps. Based on the workshop findings, we identify specific opportunities to utilize observations and models, particularly a combination of them, to enable and accelerate progress in determining the mechanisms of rapid Arctic change and its mid-latitude linkages.Observations: Due to the remoteness and harsh environmental conditions of the Arctic, in situ observational time series are highly limited spatially and temporally in the region.Six recommendations to expand approaches using observational datasets and analyses of Arctic change and mid-latitude linkages include: Synthesize new Arctic observations;Create physically-based sea ice-ocean surface forcing datasets;Systematically employ proven and new metrics;Analyze paleoclimate data and new longer observational datasets;Utilize new observational analysis methods that extend beyond correlative relationships; andConsider both established and new theories of atmospheric and oceanic dynamics to interpret and guide observational and modeling studies.Model experiments: We acknowledge that models provide the primary tool for gaining a mechanistic understanding of variability and change in the Arctic and at mid-latitudes. Coordinated modeling studies should include approaches using a hierarchy of models from conceptual, simple component, or coupled models to complex atmospheric climate models or fully coupled Earth system models. We further recommend to force dynamical models with consistent boundary forcings.Three recommendations to advance modeling and synthesis understanding of Arctic change and mid-latitude linkages include: Establish a Modeling Task Force to plan protocols, forcing, and output parameters for coordinated modeling experiments (Polar Amplification Model Intercomparison Project; PAMIP);Furnish experiment datasets to the community through open access (via Earth System Grid); andPromote analysis within the community of the coordinated modeling experiments to understand mechanisms for AA and to further understand pathways for Arctic mid-latitude linkages.

6.
Rev Sci Instrum ; 87(9): 093505, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27782568

RESUMO

New complex-plasma facility, Plasmakristall-4 (PK-4), has been recently commissioned on board the International Space Station. In complex plasmas, the subsystem of µm-sized microparticles immersed in low-pressure weakly ionized gas-discharge plasmas becomes strongly coupled due to the high (103-104 e) electric charge on the microparticle surface. The microparticle subsystem of complex plasmas is available for the observation at the kinetic level, which makes complex plasmas appropriate for particle-resolved modeling of classical condensed matter phenomena. The main purpose of PK-4 is the investigation of flowing complex plasmas. To generate plasma, PK-4 makes use of a classical dc discharge in a glass tube, whose polarity can be switched with the frequency of the order of 100 Hz. This frequency is high enough not to be felt by the relatively heavy microparticles. The duty cycle of the polarity switching can be also varied allowing to vary the drift velocity of the microparticles and (when necessary) to trap them. The facility is equipped with two videocameras and illumination laser for the microparticle imaging, kaleidoscopic plasma glow observation system and minispectrometer for plasma diagnostics and various microparticle manipulation devices (e.g., powerful manipulation laser). Scientific experiments are programmed in the form of scripts written with the help of specially developed C scripting language libraries. PK-4 is mainly operated from the ground (control center CADMOS in Toulouse, France) with the support of the space station crew. Data recorded during the experiments are later on delivered to the ground on the removable hard disk drives and distributed to participating scientists for the detailed analysis.

7.
Epidemiol Infect ; 144(15): 3170-3175, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27311302

RESUMO

Accurate data on the incidence of West Nile virus (WNV) disease are important for directing public health education and control activities. The objective of this project was to assess the underdiagnosis of WNV neuroinvasive disease through laboratory testing of patients with suspected viral meningitis or encephalitis at selected hospitals serving WNV-endemic regions in three states. Of the 279 patients with cerebrospinal fluid (CSF) specimens tested for WNV immunoglobulin M (IgM) antibodies, 258 (92%) were negative, 19 (7%) were positive, and two (1%) had equivocal results. Overall, 63% (12/19) of patients with WNV IgM-positive CSF had WNV IgM testing ordered by their attending physician. Seven (37%) cases would not have been identified as probable WNV infections without the further testing conducted through this project. These findings indicate that over a third of WNV infections in patients with clinically compatible neurological illness might be undiagnosed due to either lack of testing or inappropriate testing, leading to substantial underestimates of WNV neuroinvasive disease burden. Efforts should be made to educate healthcare providers and laboratorians about the local epidemiology of arboviral diseases and the optimal tests to be used in different clinical situations.


Assuntos
Encefalite Viral/epidemiologia , Meningite Viral/epidemiologia , Febre do Nilo Ocidental/epidemiologia , Vírus do Nilo Ocidental/isolamento & purificação , Adolescente , Adulto , Idoso , Anticorpos Antivirais/líquido cefalorraquidiano , Arizona/epidemiologia , California/epidemiologia , Criança , Encefalite Viral/líquido cefalorraquidiano , Encefalite Viral/virologia , Feminino , Hospitais , Humanos , Incidência , Masculino , Meningite Viral/líquido cefalorraquidiano , Meningite Viral/virologia , Pessoa de Meia-Idade , Minnesota/epidemiologia , Vigilância da População , Febre do Nilo Ocidental/líquido cefalorraquidiano , Febre do Nilo Ocidental/complicações , Adulto Jovem
8.
Fungal Biol Rev ; 26(2-3): 61-72, 2012 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-23189087

RESUMO

The pathogenic fungus Cryptococcus neoformans exhibits a striking propensity to cause central nervous system (CNS) disease in people with HIV/AIDS. Given that cryptococcal infections are generally initiated by pulmonary colonization, dissemination requires that the fungus withstand phagocytic killing, cross the alveolar-capillary interface in the lung, survive in the circulatory system and breach the blood-brain barrier. We know little about the molecular mechanisms underlying dissemination, but there is a rapidly growing list of mutants that fail to cause CNS disease. These mutants reveal a remarkable diversity of functions and therefore illustrate the complexity of the cryptococcal-host interaction. The challenge now is to extend the analysis of these mutants to acquire a detailed understanding of each step in dissemination.

9.
Phys Rev Lett ; 102(4): 045001, 2009 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-19257428

RESUMO

An attraction between negatively charged micron-sized plastic particles was observed in the bulk of a low-pressure gas-discharge plasma under microgravity conditions. This attraction had led to the formation of a boundary-free dust cluster, containing one big central particle with a radius of about 6 microm and about 30 1 microm-sized particles situated on a sphere with a radius of 190 microm and with the big particle in the center. The stability of this boundary-free dust cluster was possible due to its confinement by the plasma flux on the central dust particle.

10.
Phys Rev E Stat Nonlin Soft Matter Phys ; 71(5 Pt 2): 056401, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-16089654

RESUMO

Observations of complex plasmas under microgravity conditions onboard the International Space Station performed with the Plasma-Kristall experiment-Nefedov facility are reported. A weak instability of the boundary between the central void (region free of microparticles) and the microparticle cloud is observed at low gas pressures. The instability leads to periodic injections of a relatively small number of particles into the void region (by analogy this effect is called the "trampoline effect"). The trajectories of injected particles are analyzed providing information on the force field inside the void. The experimental results are compared with theory which assumes that the most important forces inside the void are the electric and the ion drag forces. Good agreement is found clearly indicating that under conditions investigated the void formation is caused by the ion drag force.

11.
Phys Rev E Stat Nonlin Soft Matter Phys ; 72(1 Pt 2): 016406, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16090098

RESUMO

An experimental determination of particle charge in a bulk dc discharge plasma covering a wide range of neutral gas pressures, was recently reported [S. Ratynskaia, Phys. Rev. Lett. 93, 085001 (2004)]. The charges obtained were several times smaller than the predictions of collisionless orbital motion limited theory. This discrepancy was attributed to the effect of ion-neutral collisions. In the present paper a more detailed description of this experiment is provided and additional experimental results obtained with particles of different sizes are reported. The measurements are compared with molecular dynamics simulations of particle charging for conditions similar to those of the experiment, with other available experimental data on particle charge in the bulk of gas discharges, and with a simple analytical model accounting for ion-neutral collisions. All the considered evidence indicates that ion-neutral collisions represent a very important factor, which significantly affects (reduces) the particle charge under typical discharge conditions.

12.
Dev Biol (Basel) ; 120: 101-11, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16050162

RESUMO

Although payment of blood donors is rejected by the WHO, the FDA, the EU, and the Red Cross (RC), in Germany, monetary compensation of expenses is permitted not only for plasmapheresis but also for whole blood donation. The structure and organisation of the institutions ensuring the blood supply in Germany and the pertaining aspects of blood safety will be discussed. Data reported to the health authorities show that the frequency of transfusion-transmitted infection markers in the German donor population is low and that only very few infections have been transmitted through blood. This is underlined by a detailed analysis of the paid donor population of a small university blood service (UBS). The analysis documents a very stable and reliable cohort of predominantly repeat donors. Unpaid RC donors of blood units transfused to patients at the university hospital of Marburg showed a sixteen-times higher sero-conversion rate than those of the UBS (p < 0.0001). However, in a survey, 77% of the paid donors denied continuation of blood donation in the event of payment being stopped. Therefore non-remuneration would result in acute blood supply shortages. Since increased blood shortages are to be expected anyway in the near future, all measures improving the supply of safe blood, including monetary compensation, should be objectively discussed without prejudice.


Assuntos
Doadores de Sangue , Compensação e Reparação , Plasma , Doadores de Sangue/psicologia , Transfusão de Sangue , Alemanha , Humanos , Organização Mundial da Saúde
13.
Phys Rev Lett ; 93(8): 085001, 2004 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-15447195

RESUMO

The charge of dust particles is determined experimentally in a bulk dc discharge plasma in the pressure range 20-100 Pa. The charge is obtained by two independent methods: one based on an analysis of the particle motion in a stable particle flow and another on an analysis of the transition of the flow to an unstable regime. Molecular-dynamics simulations of the particle charging for conditions similar to those of the experiment are also performed. The results of both experimental methods and the simulations demonstrate good agreement. The charge obtained is several times smaller than predicted by the collisionless orbital motion theory, and thus the results serve as an experimental indication that ion-neutral collisions significantly affect particle charging.

14.
Phys Rev Lett ; 90(5): 055003, 2003 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-12633365

RESUMO

The first experiment on the decharging of a complex plasma in microgravity conditions was conducted. After switching off the rf power, in the afterglow plasma, ions and electrons rapidly recombine and leave a cloud of charged microparticles. Because of microgravity, the particles remain suspended in the experimental chamber for a sufficiently long time, allowing precise measurements of the rest particle charge. A simple theoretical model for the decharging is proposed which agrees quite well with the experiment results and predicts the rest charge at lower gas pressures.

15.
Transfusion ; 41(1): 56-60, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11161246

RESUMO

BACKGROUND: Recently, the in vitro bleeding time test (IVBT) was proved to be a very sensitive screening method for the detection of vWD, showing rather good correlation between the closure time and the level of vWF. The vWF levels have been found to be significantly lower in healthy humans who are group O than in those who belong to the other ABO blood groups (non-group O). The aim of this study was to detect whether these differences in vWF levels in normal persons correspond to differences in nonvascular primary hemostasis when investigated by the IVBT. MATERIAL AND METHODS: Healthy blood donors (n = 162) without evidence of hemostatic disorders, without ingestion of drugs for at least 2 weeks, and with normal in vivo bleeding time endpoints, normal factor VIII clotting activity levels, normal structure of vWF multimers, and normal ristocetin-induced platelet aggregation were examined by IVBT. IVBT was performed with two automated systems (Thrombostat 4000, VDG [TST]; and a platelet function analyzer (PFA-100, Dade Behring [PFA]). CaCl2 and ADP were used as aggregants for the two TST tests (TST-CaCl2 and TST-ADP), and ADP- or epinephrine (Epi)-coated membranes were used with the two PFA tests (PFA-ADP and PFA-Epi). RESULTS: Closure time in the IVBT significantly correlated with the blood groups, but in reverse order (as did blood volume; data not shown): TST-ADP (mean +/- SD): group O, 89 +/- 14.6 seconds versus non-group O, 82 +/- 13 seconds (p<0.01); TST-CaCl(2): group O, 154 +/- 28.9 seconds versus non-group O, 140 +/- 31.3 seconds (p<0.01); PFA-ADP: group O, 91 +/- 13.4 seconds versus non-group O, 86 +/- 11.9 seconds (p<0.05); PFA-Epi: group O, 112 +/- 15.4 seconds versus non-group O, 104 +/- 16.7 seconds (p<0.05). Donors with vWF < or =77.5 % had longer closure time than those with vWF >77.5 % (p<0.05). CONCLUSION: Significant ABO-group-specific differences in nonvascular primary hemostasis could be found by IVBT. The differences are small, however, and lie within the normal range. Whether these differences have any biologic relevance can only be speculated.


Assuntos
Sistema ABO de Grupos Sanguíneos/fisiologia , Hemostasia/fisiologia , Tempo de Sangramento , Feminino , Humanos , Masculino , Valores de Referência , Fator de von Willebrand/análise
16.
Platelets ; 12(8): 462-70, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11798395

RESUMO

UNLABELLED: With the PFA-100 a sensitive and specific screening test for primary haemostasis has recently become available. An important part of the device is a capillary, providing a defined haemodynamic resistance for the perfusion of the aperture. A modified method to measure platelet function (VCP2) is presented in which the capillary essentially is replaced with an 'electronic capillary' by clamping the pressure/flow relationship. RESULTS AND CONCLUSION: Closure time (CT) and blood volume (BV) as determined by PFA-100 and VCP2 correlated well within (r = 0.922 - 0.952) and between the two methods (r = 0.86). The test variability (CV) of CT could be significantly reduced in the VCP2 method (collagen/epi 3.9 vs. 5.9%, p<0.05; collagen/ADP 3.3 vs. 6.9%, p<0.001), thus considerably increasing test reliability and reducing test variance. In preliminary clinical studies the VCP2 system showed comparable sensitivity for vWD and slightly less sensitivity regarding ASA ingestion. The test spectrum of VCP2 could be extended to more thrombocytopenic samples (< or =20 000/microl) even in combination with low haematocrit levels (20%), thus perhaps permitting the determination of the bleeding risk in bone marrow hypoplasia. Additionally, the sensitivity and applicability can easily be adapted to the desired need only by software modifications.


Assuntos
Aspirina/análogos & derivados , Tempo de Sangramento/métodos , Plaquetas/patologia , Plaquetas/fisiologia , Doenças Hematológicas/sangue , Hemostasia/fisiologia , Aspirina/análise , Tempo de Sangramento/instrumentação , Doenças da Medula Óssea/sangue , Capilares , Feminino , Hematócrito , Humanos , Masculino , Reprodutibilidade dos Testes , Trombocitopenia/sangue , Doenças de von Willebrand/sangue
17.
Artigo em Alemão | MEDLINE | ID: mdl-11824328

RESUMO

Adequate periop. analysis of hemostasis taking into account also disorders of primary hemostasis considerably contributes to prevention, early detection and appropriate treatment of hemostatic disturbances. Standard transfusion protocols are advisable in massive transfusion with respect to logistic problems. We describe an effective standard protocol based on the initial administration of blood components (red cells, plasma, platelets) in a certain fixed ratio which then is adapted according to the laboratory test results and the clinical situation of the patient. In addition, as soon as the hemostasis shows critical values, coagulation factor concentrates (prothrombin complex, fibrinogen, seldom single coagulation factors) are administered. Furthermore, desmopressin and antifibrinolytics can be successfully used in disorders of primary hemostasis, and additionally antifibrinolytics in hyperfibrinolysis or unclear diffuse bleeding.


Assuntos
Fatores de Coagulação Sanguínea/administração & dosagem , Transfusão de Componentes Sanguíneos , Hemostasia/efeitos dos fármacos , Adulto , Volume Sanguíneo/fisiologia , Desamino Arginina Vasopressina/administração & dosagem , Fibrinólise/efeitos dos fármacos , Humanos , Assistência Perioperatória
18.
Mund Kiefer Gesichtschir ; 4(4): 228-33, 2000 Jul.
Artigo em Alemão | MEDLINE | ID: mdl-10994322

RESUMO

The use of deposited autologous blood instead of allogenic blood is recommended in cases of elective maxillofacial operations if the blood transfusion probability is more than 10%. As an alternative, the controlled intraoperative normovolemic hemodilution and the preoperative use of EPO (Erytropoetin) should be considered. In a retrospective study, we analyzed 438 patients who underwent orthognathic surgery. The perioperative blood loss was determined in order to calculate the transfusion probability in case of the acceptance of 7.5 g/dl hemoglobin as the critical value in patients without cardiac failures. Only four patients undergoing Le Fort I osteotomy (1.55%) or bimaxillary osteotomy (3.03%) had to be transfused. Therefore, the statistical transfusion need was clearly below 10%. Due to this, there was no general need for autologous blood donation. However, in individual cases with low hemoglobin and/or low blood volume, a transfusion need can be predicted. In those few cases, autologous blood donation may be indicated. However, in case of a more conservative indication to transfusion (hemoglobin 10 g/dl), more than 10% of the patients with bimaxillary osteotomies would have been transfused. Autologous blood donation is then indicated according to the German regulations for transfusion. If low hemoglobin values are accepted, the exact individual blood demand should be calculated, a blood saving operation technique should be used, adequate postoperative warding is necessary, and compatible allogenic red cell concentrates should be quickly available.


Assuntos
Transfusão de Sangue Autóloga , Má Oclusão/cirurgia , Osteotomia , Adulto , Perda Sanguínea Cirúrgica/fisiopatologia , Feminino , Hemoglobinometria , Humanos , Masculino , Fatores de Risco
20.
Immunology ; 98(1): 111-5, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10469241

RESUMO

Environmental factors contribute to the pathogenesis of type 1 diabetes (insulin-dependent diabetes mellitus). Multiple low doses of streptozotocin (MLDS) induce hyperglycaemia and insulitis in mice. Previously we demonstrated that adhesion of lymphocytes to endothelium of islets is only increased when donor animals were diabetic and recipient mice had received 5 mg/kg streptozotocin (STZ). Therefore we used streptozotocin to evaluate the immunological relevance of such an irritation of islets. Lymphocytes, separated from diabetic mice (MLDS), were fluorescently labelled and injected to recipient mice that had received 5 mg/kg STZ. With in vivo microscopy we measured lymphocyte flow and adherence in islets. Expression of vascular cell adhesion molecule-1 (VCAM-1) and intracellular adhesion molecule-1 (ICAM-1) in the pancreas was assessed using immunohistochemistry. Very late antigen-4 (VLA-4) and leucocyte function-associated antigen-1 (LFA-1) expression on transferred lymphocytes was measured with flow cytometry. Pretreatment of recipients with antibodies to cytokines or silica reduced lymphocyte adherence to islet endothelium from 2.04% (goat immunoglobulin G; IgG) or 1.82% (rat IgG) to 0.47, 0.58, 0.39 or 0. 19% for monoclonal antibody (mAb) interferon-gamma (IFN-gamma), polyclonal antibody (pAb) tumour necrosis factor-alpha (TNF-alpha), pAb interleukin (IL)-1alpha or silica, respectively. Reduced adhesion was associated with a decreased expression of VCAM-1 and ICAM-1 in islets of treated recipients compared with mice treated with 5 mg/kg STZ alone. In conclusion, pretreatment of recipients with 5 mg/kg STZ leads to an increased expression of adhesion molecules in the islets and lymphocyte adhesion to islet endothelium in vivo, demonstrating an immune response of the islets. Prevention of increased expression of ICAM-1 or VCAM-1 and reduction of lymphocyte adhesion in islets by silica or antibody indicate an involvement of macrophages and macrophage derived cytokines in the generation of this immune response.


Assuntos
Citocinas/imunologia , Diabetes Mellitus Experimental/imunologia , Ilhotas Pancreáticas/imunologia , Linfócitos/fisiologia , Animais , Anticorpos Monoclonais/farmacologia , Adesão Celular/imunologia , Distribuição de Qui-Quadrado , Diabetes Mellitus Experimental/metabolismo , Citometria de Fluxo , Imuno-Histoquímica , Integrina alfa4beta1 , Integrinas/análise , Molécula 1 de Adesão Intercelular/análise , Interferon gama/imunologia , Interleucina-1/imunologia , Ilhotas Pancreáticas/química , Antígeno-1 Associado à Função Linfocitária/análise , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência , Receptores de Retorno de Linfócitos/análise , Estatísticas não Paramétricas , Fator de Necrose Tumoral alfa/imunologia , Molécula 1 de Adesão de Célula Vascular/análise
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