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Guan D, Tian L, Li W, Gao H. Using LDDMM and a kinematic cardiac growth model to quantify growth and remodelling in rat hearts under PAH. Comput Biol Med 2024; 171:108218. [PMID: 38428098 DOI: 10.1016/j.compbiomed.2024.108218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 01/20/2024] [Accepted: 02/25/2024] [Indexed: 03/03/2024]
Abstract
Pulmonary arterial hypertension (PAH) is a rapidly progressive and fatal disease, with right ventricular failure being the primary cause of death in patients with PAH. This study aims to determine the mechanical stimuli that may initiate heart growth and remodelling (G&R). To achieve this, two bi-ventricular models were constructed: one for a control rat heart and another for a rat heart with PAH. The growth of the diseased heart was estimated by warping it to the control heart using an improved large deformation diffeomorphic metric mapping (LDDMM) framework. Correlation analysis was then performed between mechanical cues (stress and strain) and growth tensors, which revealed that principal strains may serve as a triggering stimulus for myocardial growth and remodelling under PAH. The growth tensors, estimated from in vivo images, could explain 84.3% of the observed geometrical changes in the diseased heart with PAH by using a kinematic cardiac growth model. Our approach has the potential to quantify G&R using sparse in vivo images and to provide insights into the underlying mechanism of triggering right heart failure from a biomechanical perspective.
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Affiliation(s)
- Debao Guan
- School of Control Science and Engineering, Shandong University, China; School of Mathematics and Statistics, University of Glasgow, UK
| | - Lian Tian
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, UK
| | - Wei Li
- School of Control Science and Engineering, Shandong University, China
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, UK.
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2
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Furuhama A, Kitazawa A, Yao J, Matos Dos Santos CE, Rathman J, Yang C, Ribeiro JV, Cross K, Myatt G, Raitano G, Benfenati E, Jeliazkova N, Saiakhov R, Chakravarti S, Foster RS, Bossa C, Battistelli CL, Benigni R, Sawada T, Wasada H, Hashimoto T, Wu M, Barzilay R, Daga PR, Clark RD, Mestres J, Montero A, Gregori-Puigjané E, Petkov P, Ivanova H, Mekenyan O, Matthews S, Guan D, Spicer J, Lui R, Uesawa Y, Kurosaki K, Matsuzaka Y, Sasaki S, Cronin MTD, Belfield SJ, Firman JW, Spînu N, Qiu M, Keca JM, Gini G, Li T, Tong W, Hong H, Liu Z, Igarashi Y, Yamada H, Sugiyama KI, Honma M. Evaluation of QSAR models for predicting mutagenicity: outcome of the Second Ames/QSAR international challenge project. SAR QSAR Environ Res 2023; 34:983-1001. [PMID: 38047445 DOI: 10.1080/1062936x.2023.2284902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 11/13/2023] [Indexed: 12/05/2023]
Abstract
Quantitative structure-activity relationship (QSAR) models are powerful in silico tools for predicting the mutagenicity of unstable compounds, impurities and metabolites that are difficult to examine using the Ames test. Ideally, Ames/QSAR models for regulatory use should demonstrate high sensitivity, low false-negative rate and wide coverage of chemical space. To promote superior model development, the Division of Genetics and Mutagenesis, National Institute of Health Sciences, Japan (DGM/NIHS), conducted the Second Ames/QSAR International Challenge Project (2020-2022) as a successor to the First Project (2014-2017), with 21 teams from 11 countries participating. The DGM/NIHS provided a curated training dataset of approximately 12,000 chemicals and a trial dataset of approximately 1,600 chemicals, and each participating team predicted the Ames mutagenicity of each trial chemical using various Ames/QSAR models. The DGM/NIHS then provided the Ames test results for trial chemicals to assist in model improvement. Although overall model performance on the Second Project was not superior to that on the First, models from the eight teams participating in both projects achieved higher sensitivity than models from teams participating in only the Second Project. Thus, these evaluations have facilitated the development of QSAR models.
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Affiliation(s)
- A Furuhama
- Division of Genetics and Mutagenesis (DGM), National Institute of Health Sciences (NIHS), Kawasaki, Japan
| | - A Kitazawa
- Division of Genetics and Mutagenesis (DGM), National Institute of Health Sciences (NIHS), Kawasaki, Japan
| | - J Yao
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials (Chinese Academy of Sciences), Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (SIOC, CAS), Shanghai, China
| | - C E Matos Dos Santos
- Department of Computational Toxicology and In Silico Innovations, Altox Ltd, São Paulo-SP, Brazil
| | - J Rathman
- MN-AM, Nuremberg, Germany/Columbus, OH, USA
| | - C Yang
- MN-AM, Nuremberg, Germany/Columbus, OH, USA
| | | | - K Cross
- In Silico Department, Instem, Conshohocken, PA, USA
| | - G Myatt
- In Silico Department, Instem, Conshohocken, PA, USA
| | - G Raitano
- Laboratory of Environmental Toxicology and Chemistry, Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri IRCCS (IRFMN), Milano, Italy
| | - E Benfenati
- Laboratory of Environmental Toxicology and Chemistry, Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri IRCCS (IRFMN), Milano, Italy
| | | | | | | | | | - C Bossa
- Environment and Health Department, Istituto Superiore di Sanità (ISS), Rome, Italy
| | - C Laura Battistelli
- Environment and Health Department, Istituto Superiore di Sanità (ISS), Rome, Italy
| | - R Benigni
- Environment and Health Department, Istituto Superiore di Sanità (ISS), Rome, Italy
- Alpha-PreTox, Rome, Italy
| | - T Sawada
- Faculty of Regional Studies, Gifu University, Gifu, Japan
- xenoBiotic Inc, Gifu, Japan
| | - H Wasada
- Faculty of Regional Studies, Gifu University, Gifu, Japan
| | - T Hashimoto
- Faculty of Regional Studies, Gifu University, Gifu, Japan
| | - M Wu
- Massachusetts Institute of Technology, Cambridge, MA, USA
| | - R Barzilay
- Massachusetts Institute of Technology, Cambridge, MA, USA
| | - P R Daga
- Simulations Plus, Lancaster, CA, USA
| | - R D Clark
- Simulations Plus, Lancaster, CA, USA
| | | | | | | | - P Petkov
- LMC - Bourgas University, Bourgas, Bulgaria
| | - H Ivanova
- LMC - Bourgas University, Bourgas, Bulgaria
| | - O Mekenyan
- LMC - Bourgas University, Bourgas, Bulgaria
| | - S Matthews
- Computational Pharmacology & Toxicology Laboratory, Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - D Guan
- Computational Pharmacology & Toxicology Laboratory, Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - J Spicer
- Computational Pharmacology & Toxicology Laboratory, Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - R Lui
- Computational Pharmacology & Toxicology Laboratory, Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Y Uesawa
- Department of Medical Molecular Informatics, Meiji Pharmaceutical University, Tokyo, Japan
| | - K Kurosaki
- Department of Medical Molecular Informatics, Meiji Pharmaceutical University, Tokyo, Japan
| | - Y Matsuzaka
- Department of Medical Molecular Informatics, Meiji Pharmaceutical University, Tokyo, Japan
| | - S Sasaki
- Department of Medical Molecular Informatics, Meiji Pharmaceutical University, Tokyo, Japan
| | - M T D Cronin
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
| | - S J Belfield
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
| | - J W Firman
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
| | - N Spînu
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
| | - M Qiu
- Evergreen AI, Inc, Toronto, Canada
| | - J M Keca
- Evergreen AI, Inc, Toronto, Canada
| | - G Gini
- Department of Electronics, Information and Bioengineering (DEIB), Politecnico di Milano, Milano, Italy
| | - T Li
- Division of Bioinformatics and Biostatistics, National Center for Toxicological Research, U.S. Food and Drug Administration (NCTR/FDA), Jefferson, AR, USA
| | - W Tong
- Division of Bioinformatics and Biostatistics, National Center for Toxicological Research, U.S. Food and Drug Administration (NCTR/FDA), Jefferson, AR, USA
| | - H Hong
- Division of Bioinformatics and Biostatistics, National Center for Toxicological Research, U.S. Food and Drug Administration (NCTR/FDA), Jefferson, AR, USA
| | - Z Liu
- Division of Bioinformatics and Biostatistics, National Center for Toxicological Research, U.S. Food and Drug Administration (NCTR/FDA), Jefferson, AR, USA
- Integrative Toxicology, Nonclinical Drug Safety, Boehringer Ingelheim Pharmaceuticals, Inc, Ridgefield, CT, USA
| | - Y Igarashi
- Artificial Intelligence Center for Health and Biomedical Research, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
| | - H Yamada
- Artificial Intelligence Center for Health and Biomedical Research, National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
| | - K-I Sugiyama
- Division of Genetics and Mutagenesis (DGM), National Institute of Health Sciences (NIHS), Kawasaki, Japan
| | - M Honma
- Division of Genetics and Mutagenesis (DGM), National Institute of Health Sciences (NIHS), Kawasaki, Japan
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Guan D, Zhuan X, Luo X, Gao H. An updated Lagrangian constrained mixture model of pathological cardiac growth and remodelling. Acta Biomater 2023; 166:375-399. [PMID: 37201740 DOI: 10.1016/j.actbio.2023.05.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 05/03/2023] [Accepted: 05/10/2023] [Indexed: 05/20/2023]
Abstract
Progressive left ventricular (LV) growth and remodelling (G&R) is often induced by volume and pressure overload, characterized by structural and functional adaptation through myocyte hypertrophy and extracellular matrix remodelling, which are dynamically regulated by biomechanical factors, inflammation, neurohormonal pathways, etc. When prolonged, it can eventually lead to irreversible heart failure. In this study, we have developed a new framework for modelling pathological cardiac G&R based on constrained mixture theory using an updated reference configuration, which is triggered by altered biomechanical factors to restore biomechanical homeostasis. Eccentric and concentric growth, and their combination have been explored in a patient-specific human LV model under volume and pressure overload. Eccentric growth is triggered by overstretching of myofibres due to volume overload, i.e. mitral regurgitation, whilst concentric growth is driven by excessive contractile stress due to pressure overload, i.e. aortic stenosis. Different biological constituent's adaptations under pathological conditions are integrated together, which are the ground matrix, myofibres and collagen network. We have shown that this constrained mixture-motivated G&R model can capture different phenotypes of maladaptive LV G&R, such as chamber dilation and wall thinning under volume overload, wall thickening under pressure overload, and more complex patterns under both pressure and volume overload. We have further demonstrated how collagen G&R would affect LV structural and functional adaption by providing mechanistic insight on anti-fibrotic interventions. This updated Lagrangian constrained mixture based myocardial G&R model has the potential to understand the turnover processes of myocytes and collagen due to altered local mechanical stimuli in heart diseases, and in providing mechanistic links between biomechanical factors and biological adaption at both the organ and cellular levels. Once calibrated with patient data, it can be used for assessing heart failure risk and designing optimal treatment therapies. STATEMENT OF SIGNIFICANCE: Computational modelling of cardiac G&R has shown high promise to provide insight into heart disease management when mechanistic understandings are quantified between biomechanical factors and underlying cellular adaptation processes. The kinematic growth theory has been dominantly used to phenomenologically describe the biological G&R process but neglecting underlying cellular mechanisms. We have developed a constrained mixture based G&R model with updated reference by taking into account different mechanobiological processes in the ground matrix, myocytes and collagen fibres. This G&R model can serve as a basis for developing more advanced myocardial G&R models further informed by patient data to assess heart failure risk, predict disease progression, select the optimal treatment by hypothesis testing, and eventually towards a truly precision cardiology using in-silico models.
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Affiliation(s)
- Debao Guan
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
| | - Xin Zhuan
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK.
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Guan D, Gao H, Cai L, Luo X. A new active contraction model for the myocardium using a modified hill model. Comput Biol Med 2022; 145:105417. [DOI: 10.1016/j.compbiomed.2022.105417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/11/2022] [Accepted: 02/21/2022] [Indexed: 11/16/2022]
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Mei Y, Guan D, Tong X, Liu Q, Hu M, Chen G, Li C. Association of cerebral infarction with vertebral arterial fenestration using non-Newtonian hemodynamic evaluation. Math Biosci Eng 2022; 19:7076-7090. [PMID: 35730297 DOI: 10.3934/mbe.2022334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
PURPOSE Cerebral artery fenestration is a rare vascular anomaly, but its existence has been increasingly documented. The association of cerebral infarction and fenestration is of great clinical interest, and the exact underlying mechanism remains unclear. This study aims to identify risk factors contributing to cerebral infarction by computational hemodynamics analysis. METHODS Eight patients with image findings of fenestration structure were recruited in this research, in which four suffered fenestration-related cerebral infarction (A series) while the other four (B series) were set as control matched by the fenestration size. Three-dimensional models were reconstructed from the MRA images and computational simulations with non-Newtonian flow model were performed to get interested hemodynamic characteristics. RESULTS The blood flow pattern was relatively separated along two channels of fenestration in series A compared with series B cases in Group 1-2, however, no significant difference was shown in Group 3-4. Quantitatively, planes were cut in the middle of fenestrations and the ratio of mass flow rate and area was calculated at systolic peak. Results showed that the side of the dominant blood supply was opposite between A and B series, and the dominant side was also opposite between small and large fenestrations. In infarction cases, the basilar top was distributed with larger areas of detrimental hemodynamic indicators and a larger concentrated high viscosity region. CONCLUSION The flow division condition throughout the fenestration structure has a key impact on further flow redistribution and flow pattern. The blood viscosity has the potential to be a useful tool in identifying the risk factors for cerebral infarction and more emphasis should be placed on the hemodynamic environment at superior cerebellar arteries.
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Affiliation(s)
- Yuqian Mei
- School of Medical Imaging, North Sichuan Medical College, Nanchong, China
- College of Life Science, Mudanjiang Medical University, Mudanjiang, China
| | - Debao Guan
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
| | - Xinyu Tong
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Qian Liu
- College of Life Science, Mudanjiang Medical University, Mudanjiang, China
| | - Mingcheng Hu
- Department of Radiology, Hongqi Hospital Affiliated to Mudanjiang Medical University, Mudanjiang, China
| | - Guangxin Chen
- Medical Image College, Mudanjiang Medical University, Mudanjiang, China
| | - Caijuan Li
- Department of Ultrasound, Hongqi Hospital Affiliated to Mudanjiang Medical University, Mudanjiang, China
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Qi J, Guan D, Nutter J, Wang B, Rainforth W. Insights into tribofilm formation on Ti-6V-4Al in a bioactive environment: Correlation between surface modification and micro-mechanical properties. Acta Biomater 2022; 141:466-480. [PMID: 35063707 DOI: 10.1016/j.actbio.2022.01.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 12/16/2021] [Accepted: 01/14/2022] [Indexed: 12/28/2022]
Abstract
Ti-6Al-4V has been used as a surgical implant material for a long time because of its combination of strength, corrosion resistance and biocompatibility. However, there remains much that is not understood about how the surface reacts with the environment under tribocorrosion conditions. In particular, the conditions under which tribofilms form and their role on friction and wear are not clear. To evaluate the complicated nature of the dynamic surface microstructural changes on the wear track, high resolution transmission electron microscopy (TEM), scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) have been used to characterise the structure and chemical composition of the tribofilm. Detailed analysis of the formation and structure of the tribofilm and the metal surface deformation behaviour were studied as a function of applied potential and the role of proteins in the lubricant. For the first time, graphitic and onion-like carbon structures from wear debris were found in the testing solution. The presence of carbon nanostructures in the tribocorrosion process and the formation of the tribofilm leads to an improved tribocorrosion behaviour of the system, in particular a reduction in wear and friction. A detailed, quantitative, analysis of surface deformation was undertaken, in particular, the geometrically necessary dislocation (GND) density was quantified using precession electron diffraction (PET). A clear correlation between applied potential, tribofilm formation and the surface strain was established. STATEMENT OF SIGNIFICANCE: The formation of tribofilm and microstructure modification of the Ti-6Al-4V surface during tribocorrosion in a physiological environment is not fully understood. In particular, the correlation between microstructural changes and electrochemical conditions is not clear. This study presents a detailed investigation of the structure and chemical composition of tribofilms at the nanoscale during tribocorrosion tests in simulated body fluid and gives a detailed and quantitative description of the evolved surface structure. A clear correlation between applied potential, tribofilm formation and the surface strain was established. Moreover, particular attention is paid to the wear debris particles captured from the lubricating solution, including nanocarbon onion structures. The implications for tribocorrosion of the alloy in its performance as an implant are discussed.
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Abstract
This work accompanies the first part of our study "effects of dispersed fibres in myocardial mechanics: Part I passive response" with a focus on myocardial active contraction. Existing studies have suggested that myofibre architecture plays an important role in myocardial active contraction. Following the first part of our study, we firstly study how the general fibre architecture affects ventricular pump function by varying the mean myofibre rotation angles, and then the impact of fibre dispersion along the myofibre direction on myocardial contraction in a left ventricle model. Dispersed active stress is described by a generalised structure tensor method for its computational efficiency. Our results show that both the myofibre rotation angle and its dispersion can significantly affect cardiac pump function by redistributing active tension circumferentially and longitudinally. For example, larger myofibre rotation angle and higher active tension along the sheet-normal direction can lead to much reduced end-systolic volume and higher longitudinal shortening, and thus a larger ejection fraction. In summary, these two studies together have demonstrated that it is necessary and essential to include realistic fibre structures (both fibre rotation angle and fibre dispersion) in personalised cardiac modelling for accurate myocardial dynamics prediction.
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Affiliation(s)
- Debao Guan
- School of Mathematics and Statistics, University of Glasgow, UK
| | - Yingjie Wang
- School of Mathematics and Statistics, University of Glasgow, UK
| | - Lijian Xu
- Centre for Perceptual and Interactive Intelligence, The Chinese University of Hong Kong, Hong Kong, China
| | - Li Cai
- School of Mathematics and Statistics, Northwestern Polytechnical University, Xi'an, China
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, UK
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, UK
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Guan D, Mei Y, Xu L, Cai L, Luo X, Gao H. Effects of dispersed fibres in myocardial mechanics, Part I: passive response. Math Biosci Eng 2022; 19:3972-3993. [PMID: 35341283 DOI: 10.3934/mbe.2022183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It is widely acknowledged that an imbalanced biomechanical environment can have significant effects on myocardial pathology, leading to adverse remodelling of cardiac function if it persists. Accurate stress prediction essentially depends on the strain energy function which should have competent descriptive and predictive capabilities. Previous studies have focused on myofibre dispersion, but not on fibres along other directions. In this study, we will investigate how fibre dispersion affects myocardial biomechanical behaviours by taking into account both the myofibre dispersion and the sheet fibre dispersion, with a focus on the sheet fibre dispersion. Fibre dispersion is incorporated into a widely-used myocardial strain energy function using the discrete fibre bundle approach. We first study how different dispersion affects the descriptive capability of the strain energy function when fitting to ex vivo experimental data, and then the predictive capability in a human left ventricle during diastole. Our results show that the chosen strain energy function can achieve the best goodness-of-fit to the experimental data by including both fibre dispersion. Furthermore, noticeable differences in stress can be found in the LV model. Our results may suggest that it is necessary to include both dispersion for myofibres and the sheet fibres for the improved descriptive capability to the ex vivo experimental data and potentially more accurate stress prediction in cardiac mechanics.
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Affiliation(s)
- Debao Guan
- School of Mathematics and Statistics, University of Glasgow, UK
| | - Yuqian Mei
- School of Medical Imaging, North Sichuan Medical College, Sichuan, China
| | - Lijian Xu
- Centre for Perceptual and Interactive Intelligence, The Chinese University of Hong Kong, Hong Kong, China
| | - Li Cai
- School of Mathematics and Statistics, Northwestern Polytechnical University, Xi'an, China
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, UK
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, UK
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Guan D, Martínez A, Luigi-Sierra MG, Delgado JV, Landi V, Castelló A, Fernández Álvarez J, Such X, Jordana J, Amills M. Detecting the footprint of selection on the genomes of Murciano-Granadina goats. Anim Genet 2021; 52:683-693. [PMID: 34196982 DOI: 10.1111/age.13113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2021] [Indexed: 01/14/2023]
Abstract
Artificial selection is one of the major forces modifying the genetic composition of livestock populations. Identifying genes under selection could be useful to elucidate their impact on phenotypic variation. We aimed to identify genomic regions targeted by selection for dairy and pigmentation traits in Murciano-Granadina goats. Performance of a selection scan based on the integrated haplotype score test in a population of 1183 Murciano-Granadina goats resulted in the identification of 77 candidate genomic regions/SNPs. The most significant selective sweeps mapped to chromosomes 1 (69.86 Mb), 4 (41.80-49.95 Mb), 11 (65.74 Mb), 12 (31.24 and 52.51 Mb), 17 (34.76-37.67 Mb), 22 (31.75 Mb), and 26 (26.69-31.05 Mb). By using previously generated RNA-Seq data, we built a catalogue of 6414 genes that are differentially expressed across goat lactation (i.e. 78 days post-partum, early lactation; 216 days post-partum, late lactation; 285 days post-partum, dry period). Interestingly, 183 of these genes mapped to selective sweeps and several of them display functions related with lipid, protein, and carbohydrate metabolism, insulin signaling, cell proliferation, as well as mammary development and involution. Of particular interest are the CSN3 and CSN1S2 genes, which encode two major milk proteins. Additionally, we found three pigmentation genes (GLI3, MC1R, and MITF) co-localizing with selective sweeps. Performance of a genome-wide association study and Sanger sequencing and TaqMan genotyping experiments revealed that the c.801C>G (p.Cys267Trp) polymorphism in the melanocortin 1 receptor (MC1R) gene is the main determinant of the black (GG or GC genotypes) and brown (CC genotypes) colorations of Murciano-Granadina goats.
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Affiliation(s)
- D Guan
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain
| | - A Martínez
- Departamento de Genética, Universidad de Córdoba, Córdoba, 14071, Spain
| | - M G Luigi-Sierra
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain
| | - J V Delgado
- Departamento de Genética, Universidad de Córdoba, Córdoba, 14071, Spain
| | - V Landi
- Departamento de Genética, Universidad de Córdoba, Córdoba, 14071, Spain.,Department of Veterinary Medicine, University of Bari "Aldo Moro", SP. 62 per Casamassima km. 3, Valenzano, 70010, Italy
| | - A Castelló
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain.,Departament de Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain
| | - J Fernández Álvarez
- Asociación Nacional de Criadores de Caprino de Raza Murciano-Granadina (CAPRIGRAN), Fuente Vaqueros, Granada, 18340, Spain
| | - X Such
- Group of Research in Ruminants (G2R), Department of Animal and Food Science, Universitat Autònoma de Barcelona (UAB), Bellaterra, 08193, Spain
| | - J Jordana
- Departament de Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain
| | - M Amills
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain.,Departament de Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain
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Guan D, Yao J, Luo X, Gao H. Effect of myofibre architecture on ventricular pump function by using a neonatal porcine heart model: from DT-MRI to rule-based methods. R Soc Open Sci 2020; 7:191655. [PMID: 32431869 PMCID: PMC7211874 DOI: 10.1098/rsos.191655] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 02/26/2020] [Indexed: 05/17/2023]
Abstract
Myofibre architecture is one of the essential components when constructing personalized cardiac models. In this study, we develop a neonatal porcine bi-ventricle model with three different myofibre architectures for the left ventricle (LV). The most realistic one is derived from ex vivo diffusion tensor magnetic resonance imaging, and other two simplifications are based on rule-based methods (RBM): one is regionally dependent by dividing the LV into 17 segments, each with different myofibre angles, and the other is more simplified by assigning a set of myofibre angles across the whole ventricle. Results from different myofibre architectures are compared in terms of cardiac pump function. We show that the model with the most realistic myofibre architecture can produce larger cardiac output, higher ejection fraction and larger apical twist compared with those of the rule-based models under the same pre/after-loads. Our results also reveal that when the cross-fibre contraction is included, the active stress seems to play a dual role: its sheet-normal component enhances the ventricular contraction while its sheet component does the opposite. We further show that by including non-symmetric fibre dispersion using a general structural tensor, even the most simplified rule-based myofibre model can achieve similar pump function as the most realistic one, and cross-fibre contraction components can be determined from this non-symmetric dispersion approach. Thus, our study highlights the importance of including myofibre dispersion in cardiac modelling if RBM are used, especially in personalized models.
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Affiliation(s)
- Debao Guan
- School of Mathematics & Statistics, University of Glasgow, Glasgow, UK
| | - Jiang Yao
- Dassault Systemes, Johnston, RI, USA
| | - Xiaoyu Luo
- School of Mathematics & Statistics, University of Glasgow, Glasgow, UK
| | - Hao Gao
- School of Mathematics & Statistics, University of Glasgow, Glasgow, UK
- Author for correspondence: Hao Gao e-mail:
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Guan D, Ahmad F, Theobald P, Soe S, Luo X, Gao H. On the AIC-based model reduction for the general Holzapfel-Ogden myocardial constitutive law. Biomech Model Mechanobiol 2019; 18:1213-1232. [PMID: 30945052 PMCID: PMC6647490 DOI: 10.1007/s10237-019-01140-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/19/2019] [Indexed: 12/11/2022]
Abstract
Constitutive laws that describe the mechanical responses of cardiac tissue under loading hold the key to accurately model the biomechanical behaviour of the heart. There have been ample choices of phenomenological constitutive laws derived from experiments, some of which are quite sophisticated and include effects of microscopic fibre structures of the myocardium. A typical example is the strain-invariant-based Holzapfel–Ogden 2009 model that is excellently fitted to simple shear tests. It has been widely used and regarded as the state-of-the-art constitutive law for myocardium. However, there has been no analysis to show if it has both adequate descriptive and predictive capabilities for other tissue tests of myocardium. Indeed, such an analysis is important for any constitutive laws for clinically useful computational simulations. In this work, we perform such an analysis using combinations of tissue tests, uniaxial tension, biaxial tension and simple shear from three different sets of myocardial tissue studies. Starting from the general 14-parameter myocardial constitutive law developed by Holzapfel and Ogden, denoted as the general HO model, we show that this model has good descriptive and predictive capabilities for all the experimental tests. However, to reliably determine all 14 parameters of the model from experiments remains a great challenge. Our aim is to reduce the constitutive law using Akaike information criterion, to maintain its mechanical integrity whilst achieving minimal computational cost. A competent constitutive law should have descriptive and predictive capabilities for different tissue tests. By competent, we mean the model has least terms but is still able to describe and predict experimental data. We also investigate the optimal combinations of tissue tests for a given constitutive model. For example, our results show that using one of the reduced HO models, one may need just one shear response (along normal-fibre direction) and one biaxial stretch (ratio of 1 mean fibre : 1 cross-fibre) to satisfactorily describe Sommer et al. human myocardial mechanical properties. Our study suggests that single-state tests (i.e. simple shear or stretching only) are insufficient to determine the myocardium responses. We also found it is important to consider transmural fibre rotations within each myocardial sample of tests during the fitting process. This is done by excluding un-stretched fibres using an “effective fibre ratio”, which depends on the sample size, shape, local myofibre architecture and loading conditions. We conclude that a competent myocardium material model can be obtained from the general HO model using AIC analysis and a suitable combination of tissue tests.
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Affiliation(s)
- Debao Guan
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
| | - Faizan Ahmad
- School of Engineering, Cardiff University, Cardiff, UK
| | | | - Shwe Soe
- School of Engineering, Cardiff University, Cardiff, UK
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK.
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
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Guan D, Mármol-Sánchez E, Cardoso TF, Such X, Landi V, Tawari NR, Amills M. Genomic analysis of the origins of extant casein variation in goats. J Dairy Sci 2019; 102:5230-5241. [PMID: 30928270 DOI: 10.3168/jds.2018-15281] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 02/05/2019] [Indexed: 12/29/2022]
Abstract
The variation in the casein genes has a major impact on the milk composition of goats. Even though many casein polymorphisms have been identified so far, we do not know yet whether they are evolutionarily ancient (i.e., they existed before domestication) or young (i.e., they emerged after domestication). Herewith, we identified casein polymorphisms in a data set of 106 caprine whole-genome sequences corresponding to bezoars (Capra aegagrus, the ancestor of domestic goats) and 4 domestic goat (Capra hircus) populations from Europe, Africa, the Far East, and the Near East. Domestic and wild goat populations shared a substantial number of casein SNP, from 36.1% (CSN2) to 55.1% (CSN1S2). The comparison of casein variation among bezoars and the 4 domestic goat populations demonstrated that more than 50% of the casein SNP are shared by 2 or more populations, and 18 to 44% are shared by all populations. Moreover, the majority of casein alleles reported in domestic goats also segregate in the bezoar, including several alleles displaying significant associations with milk composition (e.g., the A/B alleles of the CSN1S1 and CSN3 genes, the A allele of the CSN2 gene). We conclude that much of the current diversity of the caprine casein genes comes from ancient standing variation segregating in the ancestor of modern domestic goats.
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Affiliation(s)
- D Guan
- Department of Animal Genetics, Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas-Institut de Recerca i Tecnologia Agroalimentàries-Universitat Autònoma de Barcelona-Universitat de Barcelona (CSIC-IRTA-UAB-UB), Campus Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - E Mármol-Sánchez
- Department of Animal Genetics, Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas-Institut de Recerca i Tecnologia Agroalimentàries-Universitat Autònoma de Barcelona-Universitat de Barcelona (CSIC-IRTA-UAB-UB), Campus Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - T F Cardoso
- Department of Animal Genetics, Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas-Institut de Recerca i Tecnologia Agroalimentàries-Universitat Autònoma de Barcelona-Universitat de Barcelona (CSIC-IRTA-UAB-UB), Campus Universitat Autònoma de Barcelona, Bellaterra 08193, Spain; CAPES Foundation, Ministry of Education of Brazil, Brasilia D.F., 70.040-020 Brazil
| | - X Such
- Departament de Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - V Landi
- Departamento de Genética, Universidad de Córdoba, Córdoba 14071, Spain
| | - N R Tawari
- Computational and Systems Biology, Genome Institute of Singapore, 60 Biopolis Street, Genome, #02-01, Singapore 138672
| | - M Amills
- Department of Animal Genetics, Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas-Institut de Recerca i Tecnologia Agroalimentàries-Universitat Autònoma de Barcelona-Universitat de Barcelona (CSIC-IRTA-UAB-UB), Campus Universitat Autònoma de Barcelona, Bellaterra 08193, Spain; Departament de Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
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Gao J, Guan D, Xu D, Zhao L, Zhang L, Li M. Eco-environmental synthesis of vinyl benzoate through transesterification catalyzed by Pd/C catalyst. B CHEM SOC ETHIOPIA 2018. [DOI: 10.4314/bcse.v32i2.13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Guan D, Li Y, Peng X, Zhao H, Mao Y, Cui Y. Thymoquinone protects against cerebral small vessel disease: Role of antioxidant and anti-inflammatory activities. J BIOL REG HOMEOS AG 2018; 32:225-231. [PMID: 29685000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cerebral small vessel disease (CSVD) is a leading cause of progressive decline of cognition and a major risk factor for stroke. Thymoquinone (TQ) is the major biological component of Nigella sativa (N. sativa) and its extracts. We explored the possible protective effect of TQ against CSVD in strokeprone spontaneously hypertensive SHRsp rats. Morris water maze and novel object recognition tests were conducted to evaluate memory and cognitive function. mRNA expression of inflammatory factors were determined and oxidative stress was evaluated. We showed that TQ markedly decreased the level of systolic blood pressure in SHRsp rats. TQ reduced the escape latency time and the time spent in the target quadrant in the Morris water maze test in SHRsp rats. TQ also decreased the time spent with the novel object in SHRsp rats in both short- and long-term memory tests. TQ markedly increased the capacity to distinguish between familiar objects and novel objects in the SHRsp rats in the short- and long-term memory tests. The mRNA expression of IL-1β, IL-6, monocyte chemoattractant protein-1 and cyclooxygenase-2 in the brain of SHRsp rats was remarkably decreased by TQ, indicating the reduction of inflammation. Moreover, TQ increased the activities of superoxide dismutase and catalase, decreased the malondialdehyde level and increased glutathione level in the brain of SHRsp rats, indicating the attenuation of oxidative stress. In summary, we found that TQ could effectively attenuate the blood pressure and the injury of memory and cognition under the condition of CSVD. The anti-inflammatory and antioxidant activities of TQ may be responsible for its protective effect. We demonstrate that TQ is a novel candidate for the treatment of CSVD and its neurological outcome.
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Affiliation(s)
- D Guan
- Department of The Second Clinical Medical College, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan, China
| | - Y Li
- Henan University of Traditional Chinese Medicine, Zhengzhou, Henan, China
| | - X Peng
- Henan University of Traditional Chinese Medicine, Zhengzhou, Henan, China
| | - H Zhao
- Department of The Second Clinical Medical College, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan, China
| | - Y Mao
- Department of The Second Clinical Medical College, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan, China
| | - Y Cui
- Department of The Second Clinical Medical College, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan, China
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Liang F, Guan D, Alastruey J. Determinant Factors for Arterial Hemodynamics in Hypertension: Theoretical Insights From a Computational Model-Based Study. J Biomech Eng 2018; 140:2663689. [DOI: 10.1115/1.4038430] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Indexed: 11/08/2022]
Abstract
Hypertension is a well-documented predictive factor for cardiovascular events. Clinical studies have extensively demonstrated the differential hemodynamic consequences of various antihypertensive drugs, but failed to clearly elucidate the underlying mechanisms due to the difficulty in performing a quantitative deterministic analysis based on clinical data that carry confounding information stemming from interpatient differences and the nonlinearity of cardiovascular hemodynamics. In the present study, a multiscale model of the cardiovascular system was developed to quantitatively investigate the relationships between hemodynamic variables and cardiovascular properties under hypertensive conditions, aiming to establish a theoretical basis for assisting in the interpretation of clinical observations or optimization of therapy. Results demonstrated that heart period, central arterial stiffness, and arteriolar radius were the major determinant factors for blood pressures and flow pulsatility indices both in large arteries and in the microcirculation. These factors differed in the degree and the way in which they affect hemodynamic variables due to their differential effects on wave reflections in the vascular system. In particular, it was found that the hemodynamic effects of varying arteriolar radius were considerably influenced by the state of central arterial stiffness, and vice versa, which implied the potential of optimizing antihypertensive treatment by selecting proper drugs based on patient-specific cardiovascular conditions. When analyzed in relation to clinical observations, the simulated results provided mechanistic explanations for the beneficial pressure-lowering effects of vasodilators as compared to β-blockers, and highlighted the significance of monitoring and normalizing arterial stiffness in the treatment of hypertension.
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Affiliation(s)
- Fuyou Liang
- School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE), Shanghai Jiao Tong University, Shanghai 200240, China e-mail:
| | - Debao Guan
- School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jordi Alastruey
- School of Biomedical Engineering and Imaging Sciences, King's College London, St Thomas' Hospital, London SE1 7EH, UK
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Guan D, Liang F, Gremaud PA. Comparison of the Windkessel model and structured-tree model applied to prescribe outflow boundary conditions for a one-dimensional arterial tree model. J Biomech 2016; 49:1583-1592. [PMID: 27062594 DOI: 10.1016/j.jbiomech.2016.03.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 03/18/2016] [Accepted: 03/23/2016] [Indexed: 11/30/2022]
Abstract
One-dimensional (1D) modeling is a widely adopted approach for studying wave propagation phenomena in the arterial system. Despite the frequent use of the Windkessel (WK) model to prescribe outflow boundary conditions for 1D arterial tree models, it remains unclear to what extent the inherent limitation of the WK model in describing wave propagation in distal vasculatures affect hemodynamic variables simulated at the arterial level. In the present study, a 1D model of the arterial tree was coupled respectively with a WK boundary model and a structured-tree (ST) boundary model, yielding two types of arterial tree models. The effective resistances, compliances and inductances of the WK and ST boundary models were matched to facilitate quantitative comparisons. Obtained results showed that pressure/flow waves simulated by the two models were comparable in the aorta, whereas, their discrepancies increased towards the periphery. Wave analysis revealed that the differences in reflected waves generated by the boundary models were the major sources of pressure wave discrepancies observed in large arteries. Additional simulations performed under aging conditions demonstrated that arterial stiffening with age enlarged the discrepancies, but with the effects being partly counteracted by physiological aortic dilatation with age. These findings suggest that the method adopted for modeling the outflow boundary conditions has considerable influence on the performance of a 1D arterial tree model, with the extent of influence varying with the properties of the arterial system.
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Affiliation(s)
- Debao Guan
- SJTU-CU International Cooperative Research Center, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Fuyou Liang
- SJTU-CU International Cooperative Research Center, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration(CISSE), Shanghai 200240, China
| | - Pierre A Gremaud
- Department of Mathematics, North Carolina State University, Raleigh, NC 27695, USA
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Guan D, Factor D, Liu Y, Wang Z, Kao HY. The epigenetic regulator UHRF1 promotes ubiquitination-mediated degradation of the tumor-suppressor protein promyelocytic leukemia protein. Oncogene 2015; 34:5206. [PMID: 26424573 DOI: 10.1038/onc.2015.314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Guan D, Lim JH, Peng L, Liu Y, Lam M, Seto E, Kao HY. Deacetylation of the tumor suppressor protein PML regulates hydrogen peroxide-induced cell death. Cell Death Dis 2014; 5:e1340. [PMID: 25032863 PMCID: PMC4123062 DOI: 10.1038/cddis.2014.185] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 03/18/2014] [Accepted: 03/26/2014] [Indexed: 12/29/2022]
Abstract
The promyelocytic leukemia protein (PML) is a tumor suppressor that is expressed at a low level in various cancers. Although post-translational modifications including SUMOylation, phosphorylation, and ubiquitination have been found to regulate the stability or activity of PML, little is known about the role of its acetylation in the control of cell survival. Here we demonstrate that acetylation of lysine 487 (K487) and SUMO1 conjugation of K490 at PML protein are mutually exclusive. We found that hydrogen peroxide (H2O2) promotes PML deacetylation and identified SIRT1 and SIRT5 as PML deacetylases. Both SIRT1 and SIRT5 are required for H2O2-mediated deacetylation of PML and accumulation of nuclear PML protein in HeLa cells. Knockdown of SIRT1 reduces the number of H2O2-induced PML-nuclear bodies (NBs) and increases the survival of HeLa cells. Ectopic expression of wild-type PML but not the K487R mutant rescues H2O2-induced cell death in SIRT1 knockdown cells. Furthermore, ectopic expression of wild-type SIRT5 but not a catalytic defective mutant can also restore H2O2-induced cell death in SIRT1 knockdown cells. Taken together, our findings reveal a novel regulatory mechanism in which SIRT1/SIRT5-mediated PML deacetylation plays a role in the regulation of cancer cell survival.
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Affiliation(s)
- D Guan
- Department of Biochemistry, School of Medicine, Case Western Reserve University, and Comprehensive Cancer Center of Case Western Reserve University, Cleveland, OH, USA
| | - J H Lim
- Department of Biochemistry, School of Medicine, Case Western Reserve University, and Comprehensive Cancer Center of Case Western Reserve University, Cleveland, OH, USA
| | - L Peng
- H Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Y Liu
- Department of Biochemistry, School of Medicine, Case Western Reserve University, and Comprehensive Cancer Center of Case Western Reserve University, Cleveland, OH, USA
| | - M Lam
- Department of Dermatology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH, USA
| | - E Seto
- H Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - H-Y Kao
- Department of Biochemistry, School of Medicine, Case Western Reserve University, and Comprehensive Cancer Center of Case Western Reserve University, Cleveland, OH, USA
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King PDC, Hatch RC, Bianchi M, Ovsyannikov R, Lupulescu C, Landolt G, Slomski B, Dil JH, Guan D, Mi JL, Rienks EDL, Fink J, Lindblad A, Svensson S, Bao S, Balakrishnan G, Iversen BB, Osterwalder J, Eberhardt W, Baumberger F, Hofmann P. Large tunable Rashba spin splitting of a two-dimensional electron gas in Bi2Se3. Phys Rev Lett 2011; 107:096802. [PMID: 21929260 DOI: 10.1103/physrevlett.107.096802] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Indexed: 05/13/2023]
Abstract
We report a Rashba spin splitting of a two-dimensional electron gas in the topological insulator Bi(2)Se(3) from angle-resolved photoemission spectroscopy. We further demonstrate its electrostatic control, and show that spin splittings can be achieved which are at least an order-of-magnitude larger than in other semiconductors. Together these results show promise for the miniaturization of spintronic devices to the nanoscale and their operation at room temperature.
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Affiliation(s)
- P D C King
- School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, United Kingdom
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Guan D, Higgs MH, Horton LR, Spain WJ, Foehring RC. Contributions of Kv7-mediated potassium current to sub- and suprathreshold responses of rat layer II/III neocortical pyramidal neurons. J Neurophysiol 2011; 106:1722-33. [PMID: 21697446 DOI: 10.1152/jn.00211.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
After block of Kv1- and Kv2-mediated K(+) currents in acutely dissociated neocortical pyramidal neurons from layers II/III of rat somatosensory and motor cortex, the remaining current is slowly activating and persistent. We used whole cell voltage clamp to show that the Kv7 blockers linopirdine and XE-991 blocked a current with similar kinetics to the current remaining after combined block of Kv1 and Kv2 channels. This current was sensitive to low doses of linopirdine and activated more slowly and at more negative potentials than Kv1- or Kv2-mediated current. The Kv7-mediated current decreased in amplitude with time in whole cell recordings, but in most cells the current was stable for several minutes. Current in response to a traditional M-current protocol was blocked by muscarine, linopirdine, and XE-991. Whole cell slice recordings revealed that the Q₁₀ for channel deactivation was ∼2.5. Sharp electrode current-clamp recordings from adult pyramidal cells demonstrated that block of Kv7-mediated current with XE-991 reduced rheobase, shortened the latency to firing to near rheobase current, induced more regular firing at low current intensity, and increased the rate of firing to a given current injection. XE-991 did not affect single action potentials or spike frequency adaptation. Application of XE-991 also eliminated subthreshold voltage oscillations and increased gain for low-frequency inputs (<10 Hz) without affecting gain for higher frequency inputs. These data suggest important roles for Kv7 channels in subthreshold regulation of excitability, generation of theta-frequency subthreshold oscillations, regulation of interspike intervals, and biasing selectivity toward higher frequency inputs.
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Affiliation(s)
- D Guan
- Department of Anatomy and Neurobiology, University of Tennessee, Memphis, TN 38163, USA
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Mugabe C, Liggins RT, Guan D, Manisali I, Chafeeva I, Brooks DE, Heller M, Jackson JK, Burt HM. Development and in vitro characterization of paclitaxel and docetaxel loaded into hydrophobically derivatized hyperbranched polyglycerols. Int J Pharm 2010; 404:238-49. [PMID: 21093563 DOI: 10.1016/j.ijpharm.2010.11.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 11/03/2010] [Accepted: 11/10/2010] [Indexed: 12/31/2022]
Abstract
In this study we report the development and in vitro characterization of paclitaxel (PTX) and docetaxel (DTX) loaded into hydrophobically derivatized hyperbranched polyglycerols (HPGs). Several HPGs derivatized with hydrophobic groups (C(8/10) alkyl chains) (HPG-C(8/10)-OH) and/or methoxy polyethylene glycol (MePEG) chains (HPG-C(8/10)-MePEG) were synthesized. PTX or DTX were loaded into these polymers by a solvent evaporation method and the resulting nanoparticle formulations were characterized in terms of size, drug loading, stability, release profiles, cytotoxicity, and cellular uptake. PTX and DTX were found to be chemically unstable in unpurified HPGs and large fractions (∼80%) of the drugs were degraded during the preparation of the formulations. However, both PTX and DTX were found to be chemically stable in purified HPGs. HPGs possessed hydrodynamic radii of less than 10nm and incorporation of PTX or DTX did not affect their size. The release profiles for both PTX and DTX from HPG-C(8/10)-MePEG nanoparticles were characterized by a continuous controlled release with little or no burst phase of release. In vitro cytotoxicity evaluations of PTX and DTX formulations demonstrated a concentration-dependent inhibition of proliferation in KU7 cell line. Cellular uptake studies of rhodamine-labeled HPG (HPG-C(8/10)-MePEG(13)-TMRCA) showed that these nanoparticles were rapidly taken up into cells, and reside in the cytoplasm without entering the nuclear compartment and were highly biocompatible with the KU7 cells.
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Affiliation(s)
- C Mugabe
- Division of Pharmaceutics and Biopharmaceutics, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
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Guan D, Pettis G. Intergeneric conjugal gene transfer fromEscherichia colito the sweet potato pathogenStreptomyces ipomoeae. Lett Appl Microbiol 2009; 49:67-72. [DOI: 10.1111/j.1472-765x.2009.02619.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Guan D, Joerger RD, Kniel KE, Calci KR, Hicks DT, Pivarnik LF, Hoover DG. Effect of high hydrostatic pressure on four genotypes of F-specific RNA bacteriophages. J Appl Microbiol 2007; 102:51-6. [PMID: 17184319 DOI: 10.1111/j.1365-2672.2006.03064.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIMS The pressure responses of four genotypes of F-specific RNA bacteriophages, f2, GA, Qbeta and SP, were evaluated with respect to pressure magnitude, treatment temperature and suspending medium. METHOD AND RESULTS The pressure responses were studied with respect to pressure magnitude (350 to 600 MPa), treatment temperature (-10 to 50 degrees C) and suspending media. Phages f2 and GA had much higher pressure resistances than Qbeta and SP. Pressure resistances of Qbeta and SP were enhanced with increase in salt concentrations in the range of 350 to 600 MPa from -10 to 50 degrees C in PBS. Qbeta and SP had greater pressure resistances when suspended in phosphate-buffered saline (PBS) with added glucose (5%, w/w), UHT whole milk and Dulbecco's Modified Eagle's Medium plus 10% fetal bovine sera than they did in PBS. Two surfactants, sucrose laurate and monolaurin, and one chelating agent, ethylenediamine tetraacetic acid (EDTA), increased the pressure resistance of Qbeta and SP, but had modest effect on either f2 or GA. CONCLUSIONS Four representative F-specific RNA bacteriophages, f2 (serotype I), GA (serotype II), Qbeta (serotype III) and SP (serotype IV) showed different resistances to hydrostatic pressure in the range of 350-600 MPa. SIGNIFICANCE AND IMPACT OF THE STUDY This study screened for practical surrogates of HAV for validation of commercial high hydrostatic pressure processing.
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Affiliation(s)
- D Guan
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA
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Guan D, Tkatch T, Surmeier DJ, Armstrong WE, Foehring RC. Kv2 subunits underlie slowly inactivating potassium current in rat neocortical pyramidal neurons. J Physiol 2007; 581:941-60. [PMID: 17379638 PMCID: PMC2170822 DOI: 10.1113/jphysiol.2007.128454] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We determined the expression of Kv2 channel subunits in rat somatosensory and motor cortex and tested for the contributions of Kv2 subunits to slowly inactivating K+ currents in supragranular pyramidal neurons. Single cell RT-PCR showed that virtually all pyramidal cells expressed Kv2.1 mRNA and approximately 80% expressed Kv2.2 mRNA. Immunocytochemistry revealed striking differences in the distribution of Kv2.1 and Kv2.2 subunits. Kv2.1 subunits were clustered and located on somata and proximal dendrites of all pyramidal cells. Kv2.2 subunits were primarily distributed on large apical dendrites of a subset of pyramidal cells from deep layers. We used two methods for isolating currents through Kv2 channels after excluding contributions from Kv1 subunits: intracellular diffusion of Kv2.1 antibodies through the recording pipette and extracellular application of rStromatoxin-1 (ScTx). The Kv2.1 antibody specifically blocked the slowly inactivating K+ current by 25-50% (at 8 min), demonstrating that Kv2.1 subunits underlie much of this current in neocortical pyramidal neurons. ScTx (300 nM) also inhibited approximately 40% of the slowly inactivating K+ current. We observed occlusion between the actions of Kv2.1 antibody and ScTx. In addition, Kv2.1 antibody- and ScTx-sensitive currents demonstrated similar recovery from inactivation and voltage dependence and kinetics of activation and inactivation. These data indicate that both agents targeted the same channels. Considering the localization of Kv2.1 and 2.2 subunits, currents from truncated dissociated cells are probably dominated by Kv2.1 subunits. Compared with Kv2.1 currents in expression systems, the Kv2.1 current in neocortical pyramidal cells activated and inactivated at relatively negative potentials and was very sensitive to holding potential.
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Affiliation(s)
- D Guan
- Department of Anatomy and Neurobiology, University of Tennessee, 855 Monroe Avenue, Memphis, TN 38163, USA
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Abstract
Pyramidal neurons from layers II/III of somatosensory and motor cortex express multiple Kv1 α-subunits and a current sensitive to block by α-dendrotoxin (α-DTX). We examined functional roles of native Kv1 channels in these cells using current-clamp recordings in brain slices and current- and voltage-clamp recordings in dissociated cells. α-DTX caused a significant negative shift in voltage threshold for action potentials (APs) and reduced rheobase. Correspondingly, a ramp-voltage protocol revealed that the α-DTX–sensitive current activated at subthreshold voltages. AP width at threshold increased with successive APs during repetitive firing. The steady-state threshold width for a given firing rate was similar in control and α-DTX, despite an initially broader AP in α-DTX. AP voltage threshold increased similarly during a train of spikes under control conditions and in the presence of α-DTX. α-DTX had no effect on input resistance or resting membrane potential and modest effects on the amplitude or width of a single AP. Accordingly, experiments using AP waveforms (APWs) as voltage protocols revealed that α-DTX–sensitive current peaked late during the AP repolarization phase. Application of α-DTX increased the rate of firing to intracellular current injection and increased gain (multiplicative effects), but did not alter spike-frequency adaptation. Consistent with these findings, voltage-clamp experiments revealed that the proportion of outward current sensitive to α-DTX was highest during the interval between two APWs, reflecting slow deactivation kinetics at −50 mV. Finally, α-DTX did not alter the selectivity of pyramidal neurons for DC versus time-varying stimuli.
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Affiliation(s)
- D Guan
- Department of Anatomy and Neurobiology, University of Tennessee, 855 Monroe Avenue, Memphis, TN 38163, USA
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Malkin R, Jackson S, Nguyen J, Yang Z, Guan D. Reply to “On the Optimal Defibrillation Waveform—How to Reconcile Theory and Experiment?”. IEEE Trans Biomed Eng 2006. [DOI: 10.1109/tbme.2006.878554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Guan D, Lee JCF, Tkatch T, Surmeier DJ, Armstrong WE, Foehring RC. Expression and biophysical properties of Kv1 channels in supragranular neocortical pyramidal neurones. J Physiol 2005; 571:371-89. [PMID: 16373387 PMCID: PMC1796796 DOI: 10.1113/jphysiol.2005.097006] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Potassium channels are extremely diverse regulators of neuronal excitability. As part of an investigation into how this molecular diversity is utilized by neurones, we examined the expression and biophysical properties of native Kv1 channels in layer II/III pyramidal neurones from somatosensory and motor cortex. Single-cell RT-PCR, immunocytochemistry, and whole cell recordings with specific peptide toxins revealed that individual pyramidal cells express multiple Kv1 alpha-subunits. The most abundant subunit mRNAs were Kv1.1 > 1.2 > 1.4 > 1.3. All of these subunits were localized to somatodendritic as well as axonal cell compartments. These data suggest variability in the subunit complexion of Kv1 channels in these cells. The alpha-dendrotoxin (alpha-DTX)-sensitive current activated more rapidly and at more negative potentials than the alpha-DTX-insensitive current, was first observed at voltages near action potential threshold, and was relatively insensitive to holding potential. The alpha-DTX-sensitive current comprised about 10% of outward current at steady-state, in response to steps from -70 mV. From -50 mV, this percentage increased to approximately 20%. All cells expressed an alpha-DTX-sensitive current with slow inactivation kinetics. In some cells a transient component was also present. Deactivation kinetics were voltage dependent, such that deactivation was slow at potentials traversed by interspike intervals during repetitive firing. Because of its kinetics and voltage dependence, the alpha-DTX-sensitive current should be most important at physiological resting potentials and in response to brief stimuli. Kv1 channels should also be important at voltages near threshold and corresponding to interspike intervals.
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Affiliation(s)
- D Guan
- Department of Anatomy and Neurobiology, University of Tennessee, 855 Monroe Avenue, Memphis, TN 38163, USA
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Abstract
OBJECTIVE CYP3A is the major enzyme responsible for metabolism of the calcineurin inhibitors cyclosporine (CsA) and tacrolimus. Our objective was to determine the relationship between genetic polymorphisms of CYP3A5 with respect to interindividual variability in CsA and tacrolimus pharmacokinetics. METHODS Kidney transplant recipients receiving CsA (n = 137) or tacrolimus (n = 30) were genotyped for CYP3A5*3 and *6 by a PCR/RFLP method. The patients were grouped according to the CYP3A5 genotype. Dose-adjusted trough levels were correlated with the corresponding genotype. RESULTS At 3, 6, and 12 months, the tacrolimus dose-adjusted trough levels (dose-adjusted C0) showed a statistically significant difference between the group of CYP3A5*3/*3 (n = 19) and the group of CYP3A5*1 allele carriers. The former was higher than the latter. The CsA dose-adjusted C0 and the actual C0 did not display a significant relation (P < .05) between the group of CYP3A5*3/*3 and the group of CYP3A5*1 allele carriers. CONCLUSION Patients with the CYP3A5*3/*3 genotype require less tacrolimus to reach target concentrations compared to those with the CYP3A5*1 allele.
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Affiliation(s)
- Y Zhao
- The First Hospital of Tsinghua University, Beijing, China
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Guan D, Kniel K, Calci KR, Hicks DT, Pivarnik LF, Hoover DG. Response of four types of coliphages to high hydrostatic pressure. Food Microbiol 2005; 23:546-51. [PMID: 16943050 DOI: 10.1016/j.fm.2005.09.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 09/14/2005] [Accepted: 09/14/2005] [Indexed: 11/18/2022]
Abstract
Pressure inactivation of four types of coliphages, varphiX 174 (ssDNA virus), MS2 (ssRNA virus), lambda imm434 (dsDNA virus) and T4 (dsDNA virus), was studied to evaluate their potential as human enteric viral surrogates for use in validation of commercial pressure processing treatments. Phage varphiX 174 demonstrated an unexpected high resistance to pressure with no more than 1-log(10) reduction observed following exposures to 350-600 MPa. There was no greater than 1-log(10) reduction below 500 MPa for MS2 in modified phosphate-buffered saline, but a 3.3-log(10) reduction was observed for MS2 pressurized at 600 MPa. Coliphages lambda imm434 and T4 were relatively sensitive to pressure in demonstrating inactivation at 350 MPa. At 21 degrees C, lambda imm434 was inactivated in modified phosphate-buffered saline or Dulbecco's Modified Eagle's Medium plus 5% fetal bovine sera by at least 7.5-log(10) when exposed to 400 MPa for 5 min. Treatment at 450 MPa for 5 min was necessary to obtain a log(10) reduction of 6-7 for T4.
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Affiliation(s)
- D Guan
- Department of Animal and Food Sciences, University of Delaware, Newark, 19716-2150, USA
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Abstract
OBJECTIVE To investigate the expression of CD158b on peripheral blood lymphocytes after kidney transplantation. METHODS Sixty two kidney transplant patients were divided into two groups (normal group and rejection group) according to pathologic results and clinical situation. Blood samples were assessed for percentage of CD3+; CD19+; CD3-CD16/56+; CD3+CD158b+; CD19+CD158b+, and CD3-CD16/56+CD158b+ subsets. RESULTS The percentages of CD3+ cells preop as well as at 1 and 7 postoperative and the day acute rejection happened were 60.06 +/- 4.67, 40.43 +/- 4.11, 31.67 +/- 4.04, and 39.21 +/- 5.20, respectively. The percentages of CD3-CD16/56+ were 21.65 +/- 1.79, 33.84 +/- 5.45, 38.10 +/- 4.86, and 39.53 +/- 4.80, respectively. The percentages of CD3+CD158b+ were 1.46 +/- 0.31, 1.88 +/- 0.70, 2.03 +/- 1.04, and 0.65 +/- 0.12, respectively. The percentages of CD3-CD16/56+CD158b+ were 5.87 +/- 1.24, 3.57 +/- 0.57, 2.82 +/- 0.45, and 1.60 +/- 0.33, respectively. CONCLUSIONS The percentage of CD3+ cells in the normal and the rejection groups decreased significantly. The percentages of CD158b+T cells decreased significantly after acute rejection. The percentage of CD158b+NK cells decreased significantly after kidney transplantation, decreasing gradually after acute rejection. The percentage of CD158b+ total T cells decreased significantly following acute rejection. The percentage of CD3-CD16/56+CD158b+ of total NK cells decreased significantly after kidney transplantation and after acute rejection. Because few factors interfere with the expression of CD158b on NK cells, monitoring of this marker may be accurate and sensitive.
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Affiliation(s)
- N Kang
- The Department of Urology and Pathology, Beijing Chaoyang Hospital, Beijing, China
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Al-Holy M, Quinde Z, Guan D, Tang J, Rasco B. Thermal inactivation of Listeria innocua in salmon (Oncorhynchus keta) caviar using conventional glass and novel aluminum thermal-death-time tubes. J Food Prot 2004; 67:383-6. [PMID: 14968974 DOI: 10.4315/0362-028x-67.2.383] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Differences in the come-up times and thermal inactivation parameters of Listeria innocua in salmon (Oncorhynchus keta) caviar containing 2.5% salt using conventional thermal-death-time (TDT) glass tubes and a novel aluminum tube were tested and compared. Generally, the come-up times and decimal reduction times (D-values) were shorter and the change in temperature required to change the D-value (z-value) was longer in the aluminum than in the glass tubes. The D-values at 60, 63, and 65 degrees C for the aluminum TDT tubes were 2.97, 0.77, and 0.40 min, respectively, and for the glass TDT tubes, these values were 3.55, 0.84, and 0.41 min. The z-values were 5.7 degrees C in the aluminum and 5.3 degrees C in the glass. Because of the shorter come-up time, the aluminum TDT tubes may provide a more precise measurement of microbial thermal inactivation than the glass TDT tubes, particularly for viscous materials, solid foods, and foods containing particulate matter.
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Affiliation(s)
- M Al-Holy
- Department of Food Science and Human Nutrition, Box 646376, Washington State University, Pullman, Washington 99164-6376, USA.
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Zhang Y, Guan DL, Xia CQ, Han ZY, Xu JJ, Gao JZ, Wu KR, Zhang YG, Guan D. Relationship between the expression levels of CD61, CD63, and PAC-1 on platelet surface in peripheral blood and the transplanted kidney function. Transplant Proc 2003; 35:1360-3. [PMID: 12826159 DOI: 10.1016/s0041-1345(03)00469-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To analyze the relationships between the expression levels of CD61, CD63, and PAC-1 on the platelet surface and the incidences of acute rejection and tubular necrosis as well as the recovery of graft function after renal transplantation. METHODS The expression levels of CD61, CD63, and PAC-1 on platelet surfaces were assayed by flow cytometry in 86 patients with different stages of uremia before and after transplantation. Patients were divided into three groups: 29 patients with normal graft function, 30 with acute rejection, and 27 with acute tubular necrosis. Patients with acute rejection were randomly assigned into groups treated with or without anticoagulants. RESULTS The expression levels of CD61, CD63, and PAC-1 on platelet surfaces significantly increased (P <.05) among patients with acute rejection, as compared with those with normal graft function or acute tubular necrosis. Compared with controls, the expression levels of CD61, CD63, and PAC-1 were lower among acute rejection patients who, received anticoagulant therapy. The recovery time for graft function shorter and, the 1-year patients and graft survival rates higher. CONCLUSIONS The pretransplant expression levels of CD61, CD63, and PAC-1 on platelet surface were significantly higher among patients with acute rejection, suggesting that this complication rather than acute tubular necrosis may be related to platelet activation. Patients with acute rejection displayed benefit from anticoagulant therapy.
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Affiliation(s)
- Y Zhang
- Department of Urology, Chaoyang Hospital, Capital Medical University, Beijing, China
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Guan D, Gray P, Kang DH, Tang J, Shafer B, Ito K, Younce F, Yang T. Microbiological Validation of Microwave-Circulated Water Combination Heating Technology by Inoculated Pack Studies. J Food Sci 2003. [DOI: 10.1111/j.1365-2621.2003.tb09661.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Li Y, Zhao Y, Guan D. [Land degradation and landscape ecological construction in Liaoning Province]. Ying Yong Sheng Tai Xue Bao 2001; 12:601-4. [PMID: 11758393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
The degradation degree, area and distribution of three types of degraded land caused by erosion, desertification and salinization were investigated in Liaoning Province by using landsat TM 1:250,000 and GIS Data. The area of eroded, desertificated and salinized land occupied 92.5%, 3.39% and 2.22% of the total provincial land area, respectively. Therefore, the land in this province was classified into three degradation regions: contemporary erosion degradation, geological erosion degradation, and desertification and salinization degradation region. The characteristics and the cause of degradation for each region were also analyzed. According to the local situation and the theory of landscape ecology, some landscape construction and restoration models were proposed.
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Affiliation(s)
- Y Li
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016.
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Guan D, Date T. [Determination of DNA binding domains in hepatitis C virus core protein]. Zhonghua Gan Zang Bing Za Zhi 2001; 9:160-2. [PMID: 11412392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
OBJECTIVE To determine the DNA binding domain in hepatitis C virus core protein and otelucidate the significance of binding. METHODS Segments of hepatitis C virus core protein were expressed in E.coli as fusion forms with glutathion S-transferase (GST). The core proteins were immobilized in SDS-PAGE gel after removing SDS from the gel by washing. (32)P-ATP labeled oligonucleotides were electrophoresed through the gel in TAE buffer. The binding of DNA with core protein was detected by autoradiography. RESULTS There were at least two DNA binding domains in the HCV core protein, the first locating at 10~16aa and the second at 46-70aa. The second region was divided into three adjacent parts, which could bind core protein independently. Core protein bound to single strand DNA as well as to double strand DNA without sequence specificity. CONCLUSIONS DNA binding regions of HCV core protein locate at its N-terminus. The binding regions of HCV core protein overlap its nucleus transfer signals and they bind to target DNA unselectively, suggesting a possible mechanism for its multifunction. The result provides basic data for understanding the biological function of HCV core protein.
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Affiliation(s)
- D Guan
- Department of Infectious Disease, 202nd Hospital of PLA, Shenyang 110003, China
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Guan D. [Energy production of plants in grass, Dicranopteris dichotoma and Rhodomyrtus tomentosa communities in Hong Kong]. Ying Yong Sheng Tai Xue Bao 2001; 12:374-8. [PMID: 11758416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
With harvest method and caloric value analysis, this paper studied the caloric values, standing energy, net fixed energy and net standing energy increment of three plant communities i.e., grass, Dicranopteris dichotoma and Rhodomyrtus tomentosa, in Hong Kong. The results showed that the caloric value was higher in D. dichotoma community and lower in grass community. The standing energy of plants in grass, D. dichotoma and R. tomentosa community was 18,638, 38,436 and 65,632 kJ.m-2; net fixed energy was 13,286, 20,354 and 18,784 kJ.m-2.yr-1; and net standing energy increment was 3437, 9626 and 6695 kJ.m-2.yr-1, respectively. Compared with southern subtropical evergreen broad-leaved forest, the standing energy, net fixed energy and net standing energy increment were lower in grass, D. dichotoma and R. tomentosa communities, which resulted from deforestation and other human disturbance. This indicated that vegetation conversion due to human disturbance would reduce the utilization coefficient of solar energy. Net fixed energy was also found to be reduced significantly with increasing intensity of human disturbance.
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Affiliation(s)
- D Guan
- Department of Environmental Science, Zhongshan University, Guangzhou 510275.
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Guan D, Zhu T, Xing Y. [Geostrophic deviation analysis of regional effects of protective forest system in reducing windspeed in north Liaoning plain]. Ying Yong Sheng Tai Xue Bao 2001; 12:23-6. [PMID: 11813426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
East Asian synoptic charts and ground wind data in April and May of four counties of north Liaoning plain were selected to calculate the regional effects of protective forest system in reducing windspeed by geostrophic deviation method. The results show that the protection effects increased with increasing forestration area. Different protection effects of protective forest appeared at different daytime, with the greatest at 14:00 and smallest at 2:00, and the average windspeed reduced 13.3%. The characteristics of the geostrophic deviation method was also discussed.
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Affiliation(s)
- D Guan
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016
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Affiliation(s)
- J Wang
- Institute of Urology, Beijing Red Cross Chaoyang Hospital, Beijing, China
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He B, Han X, Liu J, Han Z, Guan D, Gao J. [MMF and CyA in the prevention of early acute rejection after renal transplantation]. Zhonghua Wai Ke Za Zhi 2000; 38:683-5. [PMID: 11832139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To investigate the effect of MMF and low dose CyA on the prevention of early acute rejection after renal transplantation. METHODS 146 patients with kidney transplantation were analyzed retrospectively from December 1997 to January 1999. These patients were divided into two groups according to the immunosuppressive regimen: Aza group (78 patients) and MMF group (68 patients). All patients met the following criteria: HLA mismatch </= 3 loci, lymphocytes toxicity test < 10%, PRA < 20% for second or third transplantation, warm ischemia time 5-11 minutes, and cold ischemia time 3-24 hours. RESULTS There were 24 patients with acute rejection episodes (30.77%) in the Aza group; and 10 patients (14.71%) in the MMF group, (P < 0.05). The dosage of CyA and blood concentration of CyA were significantly different; 6.00 +/- 1.21 mg x kg(-1) x d(-1) and 286.00 +/- 20.02 microg/L in the Aza group; 4.00 +/- 1.14 mg x kg(-1) x d(-1) and 204.00 +/- 20.18 microg/L in the MMF group (P < 0.001). CONCLUSIONS MMF with low dose CyA based triple regimen could prevent the acute rejection episodes effectively at the early period of post transplantation. This triple regimen can reduce the acute rejection episodes by 50%. To some extent, low dose CyA may avoid nephrotoxicity. The long-term effect of this regimen on allograft is still needed to observe.
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Affiliation(s)
- B He
- Department of Urology, Beijing Red Cross Chaoyang Hospital, Capital University of Medical Sciences, Beijing 100020, China
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Guan D, Fang Z. Advances in TCM treatment of primary hepatocarcinoma. J TRADIT CHIN MED 2000; 20:223-6. [PMID: 11038988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- D Guan
- Preclinical School of Shanghai University of TCM and Pharmacy
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He B, Guan D, Gao J, Han X, Liu J, Han Z, Xu J. [Simultaneous pancreas-kidney transplantation for the treatment of type I diabetes with end-stage renal disease]. Zhonghua Wai Ke Za Zhi 2000; 38:582-4. [PMID: 11832112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To demonstrate whether simultaneous pancreas-kidney transplantation is practical for the treatment of Type I diabetes with end-stage renal disease. METHODS Eight cases of combined pancreas-kidney transplantation were performed in our institute. The age ranged from 35 years to 48 years (average 43.46 years). All cases were diagnosed as type I diabetes with end-stage nephropathy, two cases with blindness due to retinopathy. The case history ranged from 2 years to 22 years. Pancreas allograft was placed in the right iliac fossa with pancreas exocrine drainage to bladder, whereas renal allograft the in left iliac fossa. Initial immunosuppression regimen is quadruple. RESULTS Seven patient could be insulin free after transplantation, with normal fasting blood glucose. One patient received insulin treatment for 40 days after operation. One patient survived 1 year and 9 months after transplantation with normal functioning pancreas allograft and kidney allograft. Four patient survived 2 months with normal allograft function. Fasting blood glucose was between 4.5 and 6.2 mmol/L; Cr was between 53 and 106 micromol/L. Diet control was not necessary. Two patient died of encephalorrhagia, and 1 pancreatic vascular thrombosis and necrotic pancreatitis. CONCLUSIONS Combined pancreas-kidney transplantation is feasible to treat type I diabetes with end-stage nephropathy. Functional pancreas allograft could be procured in the present condition. Pancreatic exocrine is drained to bladder. The diagnosis of acute rejection could be made earlier by detecting urine amylase. Heparin should be added in order to prevent pancreatic thrombosis.
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Affiliation(s)
- B He
- Institute of Urology, Capital University of Medical Sciences, Beijing 100020, China
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Guan D, Zhu T. [Wind tunnel experiment on canopy structural parameters of isolated tree and wind velocity field characters nearby]. Ying Yong Sheng Tai Xue Bao 2000; 11:202-4. [PMID: 11767595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
The canopy structural parameters(porosity beta and permeability alpha) of isolated tree, and the wind velocity field character nearby were analyzed by wind tunnel experiment. The results show that alpha and beta fitted the function of alpha = beta 0.6, and the wind velocity nearby decreased in ellipsoid contour. The contour increased with increasing tree height and canopy width, and decreased with increasing permeability (or porosity). The isotach became the shape of ellipses or elliptic segments in horizontal and vertical plans.
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Affiliation(s)
- D Guan
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015
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44
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Li Z, Wang L, Guan D. [Landscape heterogeneity of urban vegetation in Guangzhou]. Ying Yong Sheng Tai Xue Bao 2000; 11:127-30. [PMID: 11766569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Seven indexes were used to study the landscape heterogeneity of vegetation in Guangzhou City. The results show that the patch density was 11.8 patches.km-2 and the line corridor density was 1.87 km.km-2. In old urban area, the vegetation landscape was characterized by small patches, heavy fragmentation, high diversity and random distribution, showing a highly heterogeneous spatial pattern, while in new urban area, the vegetation landscape was characterized by big patches and even distribution. Therefore, when the size of vegetation area was the same, the even distribution of vegetation could improve the landscape heterogeneity and make the ecological function more effective.
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Affiliation(s)
- Z Li
- College of Earth and Environmental Sciences, Zhongshan University, Guangzhou 510275
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Jin C, Guan D, Zhu T. [Spectral characteristics of solar radiation in broadleaved Korean pine forest in Changbai Mountain]. Ying Yong Sheng Tai Xue Bao 2000; 11:19-21. [PMID: 11766579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Based on the measurement above and below forest canopy and meteorological data, the spectral characteristics of solar radiation in broadleaved Korean pine forest in Changbai Mountain was analyzed. The results show that the photosynthetically active radiation(PAP) coefficients of total radiation, direct radiation and scatter radiation changed daily and yearly, with an annual averages of 0.46, 0.43 and 0.56 respectively. The average reflectivity, transmissitvity and absorptivity of single leaves of different tree species in Korean pine forest were 27.0%, 23.4%, 49.6% respectively. Single leaves nearly absorbed all of the ultraviolet radiation(UV) and 71.8% of photosynthetically active radiation, but transmitted 9.6% and reflected 18.6%. As for near-infrared radiation (NIR), the reflectivity and transmissitivity of leaves were a little less than the absorptivity. The forest canopy absorbed 93.9% PAR and 94.1% UV, but reflected and transmitted less. It absorbed 59.2%, reflected 26.3% and transmitted 14.4% NIR.
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Affiliation(s)
- C Jin
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015.
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46
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Han R, Yang G, Yin J, Wu X, Guan D. [Spectrophotometric assay of polyethyene glycol in urine using ammonium ferrothiocyanate aqueous-chloroform system]. Guang Pu Xue Yu Guang Pu Fen Xi 1999; 19:478-480. [PMID: 15819098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A spectrophotometric method for the quantitative determination of polyethylene glycol-600 (PEG-600) in urine is based on partitioning a chromophore present in ammonium ferrothiocyanate reagent into an aqueous phase and a chloroform phase in the presence of PEG. The method is simple and reproducible, and can detect PEG in a concentration of 0.25 g/L. It gives a linear response over a range of 0.25-2.5 g/L. The recovery of PEG-600 in urine is 107% and relative standard deviation is less than 5%.
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Affiliation(s)
- R Han
- School of Chemistry and Chemical Engineering, Zhengzhou University, 450052 Zhengzhou
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47
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Pan G, Hanaoka T, Yamano Y, Hara K, Ichiba M, Wang Y, Zhang J, Feng Y, Shujuan Z, Guan D, Gao G, Liu N, Takahashi K. A study of multiple biomarkers in coke oven workers--a cross-sectional study in China. Carcinogenesis 1998; 19:1963-8. [PMID: 9855010 DOI: 10.1093/carcin/19.11.1963] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We conducted a cross-sectional molecular epidemiological study of coke oven workers exposed to the established carcinogen polycyclic aromatic hydrocarbons (PAHs) to evaluate the relationships between both traditional 'exposure markers' and a series of biomarkers, including urinary 1-hydroxypyrene as a marker of internal dose, leukocyte aromatic DNA adducts as markers of biologically effective dose, serum p53 protein as a response marker and genetic polymorphisms of cytochrome P4501A1 and glutathione S-transferase MI as susceptibility markers. Twenty-five male subjects each were randomly selected from the top, middle and bottom work areas of the oven, and the control plant. They were matched for age and smoking status. The mean levels of PAH exposure, monitored by stationary and personal samplers, and of worker urinary 1-hydroxypyrene differed significantly between the top, middle and bottom of the oven and control work areas. The highest stationary and personal PAH concentrations and 1-hydroxypyrene levels were demonstrated at the top work area. Good correlations were found between the stationary PAH levels, personal PAH levels and urinary 1-hydroxypyrene levels. No positive correlations were demonstrated between aromatic DNA adduct levels and current or cumulative PAH exposure dose. In the presence of genetic polymorphisms of cytochrome P4501A1, a positive correlation was demonstrated between aromatic DNA adducts and urinary 1-hydroxypyrene levels. There was also a significant correlation between serum p53 protein levels and the cumulated benzo[a]pyrene exposure dose. Although these biomarkers have certain limitations, they are applicable to cancer epidemiology, and may contribute to our understanding of the mechanisms of carcinogenesis.
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Affiliation(s)
- G Pan
- Liaoning Public Health and Anti-epidemic Station Heping District, Shenyang, People's Republic of China
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Spannagel AW, Reeve JR, Liddle RA, Guan D, Green GM. An amino-terminal fragment of LCRF, LCRF-(1-35), has the same activity as the natural peptide. Am J Physiol 1997; 273:G754-8. [PMID: 9316481 DOI: 10.1152/ajpgi.1997.273.3.g754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A cholecystokinin (CCK)-releasing peptide, luminal CCK-releasing factor (LCRF), has been purified from rat jejunal secretion. Amino acid analysis and mass spectral analysis showed that the purified peptide is composed of 70-75 amino acid residues and has a mass of 8,136 Da. Microsequence analysis of LCRF yielded an amino acid sequence for the amino-terminal 41 residues. To determine the biologically active region of the molecule, a peptide was synthesized consisting of the amino-terminal 35 amino acids of LCRF. In this study, intraduodenal infusion of LCRF-(1-35) significantly stimulated pancreatic secretion in conscious rats. The dose-response curves to LCRF-(1-35) and to monitor peptide were similar and biphasic, with higher doses producing submaximal pancreatic secretory responses. The CCK-A receptor antagonist MK-329 abolished the pancreatic secretory response to intraduodenally infused LCRF-(1-35). These results demonstrate that LCRF biological activity is contained within the amino-terminal 35-amino acid portion of LCRF, and this fragment may be useful for investigating the role of LCRF in gastrointestinal function.
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Affiliation(s)
- A W Spannagel
- Department of Physiology, University of Texas Health Science Center, San Antonio 78284-7756, USA
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Xia S, Guan D, Lu S. [Reform of the pedicled abdominal subcorium vascular-net flap and its clinical application]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 1997; 11:291-2. [PMID: 9867932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
In order to resolve the shortcomings of traditional pedicled abdominal skin flap, the pedicled abdominal subcorium vascular-net flap was reformed and applied clinically. Twenty-eight cases with scar on hand or wrist were treated, including 20 males and 8 females. The age was ranged from 18 to 35 years old. The key point in the design was rotating 45 degrees of the flap from the primary site toward the pedicle. The ratio of the length to width of the flap was 1-1.8 : 1, and the wound of the donor site was covered by direct suture. Five to seven days later, all the flaps were divided and survived. The advantages of this flap were as follows: skin-grafting on the donor site was not necessary; the time needed for cutting the pedicle was shortened, and the flap is thinner than the traditional flap.
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Affiliation(s)
- S Xia
- Department of Hand Surgery, 2nd Clinical Hospital of Harbin Medical University, P.R. China
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50
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Abstract
Patients with early non-insulin-dependent diabetes mellitus (NIDDM) empty glucose solutions from their stomachs more rapidly than non-diabetic control subjects, and this exacerbates postprandial hyperglycaemia. To determine if accelerated gastric emptying occurred in a rat model of NIDDM and influenced postprandial hyperglycaemia, gastric emptying of glucose was measured, and the effect of slowing the gastric emptying rate on postprandial hyperglycaemia was observed. We tested eight male obese Zucker diabetic rats and eight age-matched lean Zucker controls at 10-13 weeks of age to measure gastric emptying of glucose (by gamma scintigraphy). Rats fasted overnight were gavaged with 30% glucose at 1 ml/100 g body weight. Separately, six Zucker diabetic rats and six lean controls were tested for sensitivity to the inhibitory effects of cholecystokinin and secretin on gastric emptying. The diabetic rats emptied glucose significantly faster than controls (t1/2 = 37.3 +/- 1.5 vs 58.8 +/- 2.3 min in controls), and aging exaggerated this differential. Camostat, a stimulant of cholecystokinin and secretin release, added to the glucose meal significantly slowed gastric emptying (t1/2 = 123 +/- 23 and 166 +/- 19 min, diabetic vs lean, respectively), and significantly reduced postprandial hyperglycaemia in diabetic rats. Compared to Zucker lean controls, Zucker diabetic rats were as sensitive (cholecystokinin) or more sensitive (secretin) to gastrointestinal hormones that inhibit gastric emptying. The results demonstrate accelerated gastric emptying in a rat model of NIDDM, consistant with similar observations in humans with early NIDDM. These results also support the proposal that interventions to slow gastric emptying improve glucose control in this disease.
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Affiliation(s)
- G M Green
- Department of Physiology, University of Texas Health Science Center at San Antonio 78284-7756, USA
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