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World Journal of Hepatology 2012年第3期4卷 81-90页

作者： Radan Bruha karel dvorak Jaromir Petrty 4th Department of Internal Medicine General Teaching HospitalFirst Faculty of Medicine Charles University l4th Department of Internal Medicine General Teaching HospitalFirst Faculty of Medicine Charles University

Alcohol use disorders affect millions of individuals worldwide.Alcohol consumption is directly associated with liver disease mortality and accounts for elevated social and economic costs.Alcoholic liver disease(ALD) may take the form of acute involvement(alcoholic hepatitis)or chronic liver disease(steatosis,steatohepatitis,fibrosis and cirrhosis).The severity and prognosis of alcohol-induced liver disease depends on the amount,pattern and duration of alcohol consumption,as well as on the presence of liver inflammation,diet,nutritional status and genetic predisposition of an individual.While steatosis is an almost completely benign disease,liver cirrhosis is associated with marked morbidity,mortal-ity and life expectancy shortening.The median survival of patients with advanced cirrhosis is 1-2 years.Se-vere acute alcoholic hepatitis(AH)is associated with mortality as high as 50%.It has been managed with corticoids,pentoxifylline and enteral nutrition,although evidence based data are still conflicting.Some author suggest that pentoxifylline could be a better first-line treatment in patients with severe AH.Absolute abstinence is a basic condition for any treatment of acute or chronic ALD,the other therapeutical procedure being of a supportive nature and questionable significance.Acamprosate appears to be an effective treatment strategy for supporting continuous abstinence in alco-hol dependent patients.Patients with advanced liver cirrhosis who demonstrably abstain can be considered for liver transplantation,which leads to a markedly pro-longed life expectancy.The crucial step in ALD preven-tion is in the prevention of alcohol abuse,whereas the prevention of liver injury in active alcohol abusers is not clinically applicable.

关键词： Alcohol Alcoholic liver disease Liver cirrho-sis Liver fibrosis Steatohepatitis Steatosis

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Degradable magnesium-hydroxyapatite interpenetrating phase composites processed by current assisted metal infiltration in additive-manufactured porous preforms

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Journal of Magnesium and Alloys 2022年第12期10卷 3641-3656页

作者： Mariano Casas-Luna Edgar B.Montufar Norbert Hort Sebastian Díaz-de-la-Torre JoséClaudio Méndez-García Lucie Vištejnová Adam Brínek AlešDanhel karel dvorak Jozef Kaiser Ladislav Celko Central European Institute of Technology Brno University of TechnologyPurkynova 123Brno 61200Czech Republic Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Straße 1Geesthacht 21502Germany Institute of Product and Process Innovation Leuphana University LüneburgUniversitätsallee 1Lüneburg 21335Germany Centro de Investigación e Innovación Tecnológica Instituto Politécnico NacionalCerrada de Cecati s/nMexico City 02250Mexico Biomedical Center Faculty of Medicine in PilsenCharles UniversityAlej Svobody 1655/76Plzen 32300Czech Republic Institute of Biophysics of the Czech Academy of Sciences Královopolská135Brno 61265Czech Republic Faculty of Civil Engineering Brno University of TechnologyPurkynova 139Brno 61200Czech Republic

This work explores ceramic additive manufacturing in combination with liquid metal infiltration for the production of degradable interpenetrating phase magnesium/hydroxyapatite(Mg/HA) composites. Material extrusion additive manufacturing was used to produce stoichiometric,and calcium deficient HA preforms with a well-controlled open pore network, allowing the customization of the topological relationship of the composite. Pure Mg and two different Mg alloys were used to infiltrate the preforms by means of an advanced liquid infiltration method inspired by spark plasma sintering, using a novel die design to avoid the structural collapse of the preform. Complete infiltration was achieved in 8 min, including the time for the Mg melting. The short processing time enabled to restrict the decomposition of HA due to the reducing capacity of liquid Mg. The pure Mg-base composites showed compressive yield strength above pure Mg in cast state. Mg alloy-based composites did not show higher strength than the bare alloys due to grain coarsening, but showed similar mechanical properties than other Mg/HA composites that have significantly higher fraction of metallic phase. The composites showed faster degradation rate under simulated body conditions than the bare metallic component due to the formation of galvanic pairs at microstructural level. Mg dissolved preferentially over HA leaving behind a scaffold after a prolonged degradation period. In turn, the fast production of soluble degradation products caused cell metabolic changes after 24 h of culture with not-diluted material extracts. The topological optimization and reduction of the degradation rate are the topics for future research.

关键词： Interpenetrating phase composite Biodegradable metal Topological relationship Direct ink writing Metal infiltration Computed aided design

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Osteopontin: A non-invasive parameter of portal hypertension and prognostic marker of cirrhosis

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World Journal of Gastroenterology 2016年第12期22卷 3441-3450页

作者： Radan Bruha Marie Jachymova Jaromir Petrtyl karel dvorak Martin Lenicek Petr Urbanek Tomislav Svestka Libor Vitek 4~(th) Department of Internal Medicine 1~(st) Faculty of Medicine and General University Hospital Charles University in Prague Institute of Clinical Biochemistry and Laboratory Diagnostics 1~(st) Faculty of Medicine Charles University in Prague Department of Internal Medicine Central Military Hospital and 1~(st) Faculty of Medicine Charles University in Prague

AIM: To investigate the relationship between osteopontin plasma concentrations and the severity of portal hypertension and to assess osteopontin prognostic value.METHODS: A cohort of 154 patients with confirmed liver cirrhosis(112 ethylic, 108 men, age 34-72 years)were enrolled in the study. Hepatic venous pressure gradient(HVPG) measurement and laboratory and ultrasound examinations were carried out for all patients. HVPG was measured using a standard catheterization method with the balloon wedge technique. Osteopontin was measured using the enzyme-linked immunosorbent assay(ELISA) method in plasma. Patients were followed up with a specific focus on mortality. The control group consisted of 137 healthy age- and sex- matched individuals.RESULTS: The mean value of HVPG was 16.18 ± 5.6 mm Hg. Compared to controls, the plasma levels of osteopontin in cirrhotic patients were significantly higher(P 10 mm Hg and 65% for those with HVPG ≤ 10 mm Hg(P = 0.0086, odds ratio(OR), 2.92, 95% confidence interval(CI): 1.09-7.76). Osteopontin showed a similar prognostic value to HVPG. Patients with osteopontin values above 80 ng/m L had significantly lower cumulative survival compared to those with osteopontin ≤ 80 ng/m L(37% vs 56%, P = 0.00035; OR = 2.23, 95%CI: 1.06-4.68).CONCLUSION: Osteopontin is a non-invasive parameter of portal hypertension that distinguishes patients with clinically significant portal hypertension. It is a strong prognostic factor for survival.

关键词： Cirrhosis Complications of cirrhosis Hepatic venous pressure gradient Osteopontin Portal hypertensio

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Transonic Instability in Entrance Part of Mixing Chamber of High-Speed Ejector

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Journal of Thermal Science 2005年第3期14卷 258-263,271页

作者： Vaclav dvorak Pavel Safarik Technical University of Liberec Faculty of Mechanical Engineering Division of Power Engineering Halkova 6 461 17 Liberec Czech Republic Ph.DCzech Technical University in Prague Faculty of Mechanical Engineering 207- Institute of Fluid Dynamics and Power Engineering Division of Fluid Dynamics and Thermodynamics. Technicka 4 166 07 Praha 6 Czech Republic

The paper deals with experimental and numerical study of flow structure in two-dimensional model of supersonic ejector. Schlieren pictures of flow structure were taken, static pressure distributions on side wall were measured and Fluent software to calculate the flow structure in supersonic ejector was used. For certain region of back pressure ratio pb/p02 and stagnation pressure ratio of both streams p01/p02 the terminal shock wave is close to the trailing edge of the primary flow nozzle and a transonic instability occurs. The instability causes the movement of position of boundary layer separation, the structure of shock waves changes and all flow structure oscillates. The movie of these regimes during schlieren experiments was taken and relevant numerical modelling was performed.

关键词：跨音速流动不稳定性混频震动波排除器

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Supersonic Flow Structure in the Entrance Part of a Mixing Chamber of 2D Model Ejector

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Journal of Thermal Science 2003年第4期12卷 344-349页

作者： Vaclav dvorak Pavel Safarik Technical University in Liberec Faculty of Mechanical Engineering Department of Power Engineering Equipment. Halkova 6461 17 Liberec Czech RepublicCzech Technical University in Prague Faculty of Mechanical Engineering 207.1 Institute of Fluid Dynamics and Power Engineering Division of Fluid Dynamics and Thermodynamics. Technicka 4 166 07 Praha 6 Czech Republic

The paper deals with experimental and numerical results of investigation into supersonic and transonic flow past a two-dimensional model ejector. Results of optical measurements show a flow structure and flow parameter development in the entrance part of the mixing chamber of the ejector. Numerical results are obtained by means of both the straight solution of shock waves in supersonic flow field using classical relations of parameters of shock waves and the Fluent 6 program. Results of numerical solutions are compared with experimental pictures of flow fields. Flow structure development in the mixing chamber is analysed in detail.

关键词：冲击波剪切层边界层分离超音速流超音速喷射

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Optimal design of velocity sensor for open channel flow using CFD

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International Journal of Agricultural and Biological Engineering 2017年第3期10卷 130-142页

作者： Joseph Scot dvorak Naiqian Zhang Department of Biosystems and Agricultural Engineering University of KentuckyLexingtonKentucky 40546-0276USA Department of Biological and Agricultural Engineering Kansas State UniversityManhattanKansas 66506USA

In this study,computational fluid dynamics(CFD)was used to design the geometry of a new velocity sensor for measuring open channel flows.This sensor determined velocity by observing the travel of dye carried in the flow.Evaluation of this design required the development of fluid dynamics models to determine potential errors in fluid velocity measurement due to velocity changes caused by intrusion of the sensor in the fluid.It also required an analysis technique to determine the expected sensor response to the flow fields that resulted from the CFD modeling.These models were then used to improve the geometry of the sensor to minimize the measurement error.Starting with a simple design for the sensor geometry,the CFD analysis modeled the open channel flow around the sensor as turbulent using both the k-ωand k-εReynolds Averaged Navier-Stokes(RANS)turbulence models.The model predicted that the original sensor design would underestimate the free-stream velocities of open channels by 7.9%to 2.0%across a range from 0.1 m/s to 5.0 m/s.After using CFD to improve the sensor design,the velocity measurement error was limited to less than 4%across the same velocity range.

关键词： computational fluid dynamics flow measurement sensors flow velocity open channel

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Pneumatic Measurements Downstream of a Radial Turbine Nozzle Cascade

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Journal of Thermal Science 2010年第1期19卷 42-46页

作者： Martin LUXA Rudolf dvorak David SIMURDA Jan VIMMR Department of Fluid Dynamics Institute of Thermomechanicsv.v.i.Academy of Science of the Czech RepublicPragueCzech Republic Department of Mechanics University of West Bohemia in PilsenPlzeňCzech Republic

This paper deals mainly with pneumatic measurements on a radial turbine nozzle cascade.The full radial cascade guarantees the exit flow field periodicity downstream of it.A special traversing mechanism with a five -hole conical probe moving along a circular path behind the cascade was used for flow field investigation in this type of cascade with very low aspect ratio.The analyses of results of 2D and 3D pneumatic measurements including loss coefficient values are presented.

关键词：气动测量喷嘴叶栅径向涡轮出口流场损失系数级联型周期性

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Bile acids as endogenous etiologic agents in gastrointestinal cancer

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World Journal of Gastroenterology 2009年第27期15卷 3329-3340页

作者： Harris Bernstein Carol Bernstein Claire M Payne Katerina dvorak Department of Cell Biology and Anatomy College of Medicine and Arizona Cancer Center University of ArizonaTucson Arizona 85724 United States Department of Cell Biology and Anatomy College of Medicine University of ArizonaTucson Arizona 85724 United States Hematology/Oncology Southern Arizona Veterans Affairs Health Care System Tucson Arizona 85723 United States

Bile acids are implicated as etiologic agents in cancer of the gastrointestinal (GI) tract, including cancer of the esophagus, stomach, small intestine, liver, biliary tract, pancreas and colon/rectum. Deleterious effects of bile acid exposure, likely related to carcinogenesis, include: induction of reactive oxygen and reactive nitrogen species; induction of DNA damage; stimulation of mutation; induction of apoptosis in the short term, and selection for apoptosis resistance in the long term. These deleterious effects have, so far, been reported most consistently in relation to esophageal and colorectal cancer, but also to some extent in relation to cancer of other organs. In addition, evidence is reviewed for an association of increased bile acid exposure with cancer risk in human populations, in specific human genetic conditions, and in animal experiments. A model for the role of bile acids in GI carcinogenesis is presented from a Darwinian perspective that offers an explanation for how the observed effects of bile acids on cells contribute to cancer development.

关键词：胆汁酸消化道肿瘤病原体内源性细胞凋亡人类基因 DNA损伤胃肠道

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Advanced Robotics to Address the Translational Gap in Tendon Engineering

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Cyborg and Bionic Systems 2022年第1期2022卷 221-238页

作者： Iain L.Sander Nicole dvorak Julie A.Stebbins Andrew J.Carr Pierre-Alexis Mouthuy Botnar Research Centre Nufield Department of OrthopaedicsRheumatologyand Musculoskeletal SciencesUniversity of OsfordWindmill RoadOxford 0X37LDUK Oxford Gait Laboratory Nfield Orthopaedic CentreTebbit CentreWindmill RoadOxford 0X37HEUK

Tendon disease is a significant and growing burden to healthcare systems.One strategy to address this challenge is tssueengineering.A widely held view in this feld is that mechanical stimulation provided to constructs should replicate themechanicaienvironment of native tissue as closely as possible.We review recent tendon tissue engineering studies inthisarticle and highlight limitations of conventional uniaxial tensile bioreactors used in current literature.Advanced roboticplatforms such as musculoskeletal humanoid robots and soft robotic actuators are promising technologies which may helpaddress translational gaps in tendon tissue engineering We suggest the proposed benets of these technologies and identifyrecent studies which have worked to implement these technologies in tssue engineering.Lastly,key chalenges to addressinadapting these robotic technologies and proposed future research directions for tendon tssue engineering are discussed.

关键词： directions limitations Tendon

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Role of interleukin-6 in Barrett's esophagus pathogenesis

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World Journal of Gastroenterology 2013年第15期19卷 2307-2312页

作者： Katerina dvorak Bohuslav dvorak Department of Cellular and Moleculart Medicine The University of ArizonaTucsonAZ 85724United States Department of Pediatrics and Steele Children's Research Center The University of ArizonaTucsonAZ 85724United States

Barrett's esophagus (BE) is a metaplastic lesion of the distal esophagus arising as a consequence of chronic gastroesophageal reflux disease. Multiple studies show that BE is associated with increased risk of esophageal adenocarcinoma (EAC). Epidemiological studies and animal models demonstrate that chronic inflammation triggered by repeated exposure to refluxate predisposes to the development of BE and EAC. The chronic inflammation is associated with cytokine alterations. Interleukin 6 (IL-6) is a cytokine that stimulates cell proliferation and apoptosis resistance is frequently increased in different cancers. Importantly, IL-6 and transcriptional factor signal transducer and activator of transcription 3 (STAT3) that is activated by IL-6 are also increased in BE and EAC. This review critically appraises the role of IL-6/STAT3 pathway in progression of BE to EAC from the published evidence currently available.

关键词： Barrett’s esophagus Interleukin 6 Bile acids Inflammation Apoptosis

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