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Chen DZ, Chee SP. Femtosecond laser-assisted cataract surgery for complex cataracts - A review. Indian J Ophthalmol 2024; 72:629-636. [PMID: 38648431 DOI: 10.4103/ijo.ijo_2996_23] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 01/25/2024] [Indexed: 04/25/2024] Open
Abstract
Since its inception in 2009, femtosecond laser-assisted cataract surgery (FLACS) has become an alternative to conventional phacoemulsification cataract surgery (CPCS). Clinical studies were unable to demonstrate superior visual outcomes, but revealed reduced endothelial cell loss. More recently, the cost-effectiveness of FLACS over CPCS in routine cataract surgeries has been challenged. However, the unique abilities of FLACS to customize anterior capsulotomies precisely, soften and fragment the nucleus without capsular bag stress, and create corneal incisions may have special utility in complex cataract and less-common scenarios. In this article, we review the unique role of FLACS in complex cataract surgeries and how it could play a role to improve the safety and predictability of nonroutine cataract surgery.
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Affiliation(s)
- David Z Chen
- Department of Ophthalmology, National University Hospital, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Soon-Phaik Chee
- Department of Ophthalmology, National University Hospital, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Department of Ocular Inflammation and Immunology, Singapore National Eye Centre, Singapore
- Department of Cataract, Singapore Eye Research Institute, Singapore
- Department of Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore
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2
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Chen DZ, Hernstadt DJ, Lin HA, Chee SP. Rupture of a posterior polar cataract after peribulbar block. Can J Ophthalmol 2024:S0008-4182(24)00075-9. [PMID: 38604238 DOI: 10.1016/j.jcjo.2024.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 02/09/2024] [Accepted: 03/12/2024] [Indexed: 04/13/2024]
Affiliation(s)
| | | | | | - Soon-Phaik Chee
- National University Hospital, Singapore; Singapore National Eye Centre, Singapore; Singapore Eye Research Institute, Singapore; Duke-NUS Medical School, Singapore
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3
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Chen DZ, Wang CX, Huecker JB, Russell AJ, Anadkat MJ. Risk of keratinocyte carcinomas following extracorporeal photopheresis among lung transplant recipients: A retrospective cohort study. J Am Acad Dermatol 2024; 90:388-390. [PMID: 37802186 DOI: 10.1016/j.jaad.2023.09.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 09/25/2023] [Accepted: 09/28/2023] [Indexed: 10/08/2023]
Affiliation(s)
- David Z Chen
- Washington University School of Medicine, St. Louis, Missouri
| | - Cynthia X Wang
- Division of Dermatology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Julia B Huecker
- Washington University School of Medicine, St. Louis, Missouri
| | - Aaron J Russell
- Division of Dermatology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri; Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, Missouri
| | - Milan J Anadkat
- Division of Dermatology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri.
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4
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Ganapathy A, Ballard DH, Chen DZ, Schneider M, Lanier MH, Mazaheri P, Ilahi O, Kirby JP, Raptis CA, Mellnick VM. Preoperative computed tomography in Fournier's gangrene does not delay time to surgery. Emerg Radiol 2023; 30:711-717. [PMID: 37857761 DOI: 10.1007/s10140-023-02177-y] [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: 09/14/2023] [Accepted: 10/12/2023] [Indexed: 10/21/2023]
Abstract
PURPOSE Fournier's gangrene (FG), a rapidly progressive necrotizing soft tissue infection of the external genitalia and perineum, necessitates urgent surgical debridement. The time to surgery effect of preoperative computed tomography (CT) in managing this condition is yet to be fully explored. The purpose of this study was to assess whether obtaining a preoperative CT in patients with FG impacts the time to surgical intervention. METHODS This was a single-center retrospective study of patients who underwent CT prior to surgical debridement of FG during a 9-year period vs patients who did not undergo CT. In 76 patients (male = 39, mean age = 51.8), 38 patients with FG received a preoperative CT, and 38 patients with FG did not receive CT prior to surgical debridement. Time to operating room and outcome metrics were compared between CT and non-CT groups. RESULTS The time from hospital presentation to surgical intervention was not significantly different between patients who underwent CT and those who did not (6.65 ± 3.71 vs 5.73 ± 4.33 h, p = 0.37). There were also no significant differences in cost ($130,000 ± $102,000 vs $142,000 ± $152,000, p = 0.37), mortality (8 vs 7, p = 1), duration of hospital stay (15.5 ± 15 vs 15.7 ± 11.6 days, p = 0.95), average intensive care unit stay (5.82 ± 5.38 days vs 6.97 ± 8.58 days, p = 0.48), and APACHE score (12 ± 4.65 vs 13.9 ± 5.6, p =0.12). CONCLUSION Obtaining a preoperative CT did not delay surgical intervention in patients with FG.
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Affiliation(s)
- Aravinda Ganapathy
- School of Medicine, Washington University in St. Louis, St. Louis, MO, 63110, USA
| | - David H Ballard
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd; Campus Box 8131, St. Louis, MO, 63110, USA.
| | - David Z Chen
- School of Medicine, Washington University in St. Louis, St. Louis, MO, 63110, USA
| | - McGinness Schneider
- School of Medicine, Washington University in St. Louis, St. Louis, MO, 63110, USA
| | - M Hunter Lanier
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd; Campus Box 8131, St. Louis, MO, 63110, USA
| | - Parisa Mazaheri
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd; Campus Box 8131, St. Louis, MO, 63110, USA
| | - Obeid Ilahi
- Department of Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - John P Kirby
- Department of Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Constantine A Raptis
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd; Campus Box 8131, St. Louis, MO, 63110, USA
| | - Vincent M Mellnick
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd; Campus Box 8131, St. Louis, MO, 63110, USA
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Kalidindi Y, Ganapathy AK, Nayak Y, Elumalai A, Chen DZ, Bishop G, Sanchez A, Albers B, Shetty AS, Ballard DH. Computed Tomography Attenuation of Three-Dimensional (3D) Printing Materials-Depository to Aid in Constructing 3D-Printed Phantoms. Micromachines (Basel) 2023; 14:1928. [PMID: 37893365 PMCID: PMC10609050 DOI: 10.3390/mi14101928] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/06/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023]
Abstract
Three-dimensionally printed phantoms are increasingly used in medical imaging and research due to their cost-effectiveness and customizability, offering valuable alternatives to commercial phantoms. The purpose of this study was to assess the computed tomography (CT) attenuation characteristics of 27 resin materials from Formlabs, a 3D printing equipment and materials manufacturer. Cube phantoms (both solid and hollow constructions) produced with each resin were subjected to CT scanning under varying tube current-time products with attenuation measurements recorded in Hounsfield units (HU). The resins exhibited a wide range of attenuation values (-3.33 to 2666.27 HU), closely mimicking a range of human tissues, from fluids to dense bone structures. The resins also demonstrated consistent attenuation regardless of changes in the tube current. The CT attenuation analysis of FormLabs resins produced an archive of radiological imaging characteristics of photopolymers that can be utilized to construct more accurate tissue mimicking medical phantoms and improve the evaluation of imaging device performance.
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Affiliation(s)
- Yuktesh Kalidindi
- School of Medicine, Saint Louis University, St. Louis, MO 63104, USA;
| | - Aravinda Krishna Ganapathy
- School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; (A.K.G.); (Y.N.); (D.Z.C.)
| | - Yash Nayak
- School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; (A.K.G.); (Y.N.); (D.Z.C.)
| | - Anusha Elumalai
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.E.); (G.B.); (A.S.); (A.S.S.)
| | - David Z. Chen
- School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; (A.K.G.); (Y.N.); (D.Z.C.)
| | - Grace Bishop
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.E.); (G.B.); (A.S.); (A.S.S.)
| | - Adrian Sanchez
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.E.); (G.B.); (A.S.); (A.S.S.)
| | - Brian Albers
- St. Louis Children’s Hospital Medical 3D Printing Center, BJC Healthcare, St. Louis, MO 63110, USA;
| | - Anup S. Shetty
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.E.); (G.B.); (A.S.); (A.S.S.)
| | - David H. Ballard
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.E.); (G.B.); (A.S.); (A.S.S.)
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Chen DZ, Ganapathy A, Nayak Y, Mejias C, Bishop GL, Mellnick VM, Ballard DH. Analysis of Superficial Subcutaneous Fat Camper's and Scarpa's Fascia in a United States Cohort. J Cardiovasc Dev Dis 2023; 10:347. [PMID: 37623360 PMCID: PMC10455117 DOI: 10.3390/jcdd10080347] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/03/2023] [Accepted: 08/07/2023] [Indexed: 08/26/2023] Open
Abstract
Together, the Camper's and Scarpa's fasciae form the superficial fat layer of the abdominal wall. Though they have clinical and surgical relevance, little is known about their role in body composition across diverse patient populations. This study aimed to determine the relationship between patient characteristics, including sex and body mass index, and the distribution of Camper's and Scarpa's fascial layers in the abdominal wall. A total of 458 patients' abdominal CT examinations were segmented via CoreSlicer 1.0 to determine the surface area of each patient's Camper's, Scarpa's, and visceral fascia layers. The reproducibility of segmentation was corroborated by an inter-rater analysis of segmented data for 20 randomly chosen patients divided between three study investigators. Pearson correlation and Student's t-test analyses were performed to characterize the relationship between fascia distribution and demographic factors. The ratios of Camper's fascia, both as a proportion of superficial fat (r = -0.44 and p < 0.0001) and as a proportion of total body fat (r = -0.34 and p < 0.0001), showed statistically significant negative correlations with BMI. In contrast, the ratios of Scarpa's fascia, both as a proportion of superficial fat (r = 0.44 and p < 0.0001) and as a proportion of total body fat (r = 0.41 and p < 0.0001), exhibited statistically significant positive correlations with BMI. Between sexes, the females had a higher ratio of Scarpa's facia to total body fat compared to the males (36.9% vs. 31% and p < 0.0001). The ICC values for the visceral fat, Scarpa fascia, and Camper fascia were 0.995, 0.991, and 0.995, respectively, which were all within the 'almost perfect' range (ICC = 0.81-1.00). These findings contribute novel insights by revealing that as BMI increases the proportion of Camper's fascia decreases, while the ratio of Scarpa's fascia increases. Such insights expand the scope of body composition studies, which typically focus solely on superficial and visceral fat ratios.
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Affiliation(s)
- David Z. Chen
- School of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; (D.Z.C.); (A.G.)
| | - Aravinda Ganapathy
- School of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; (D.Z.C.); (A.G.)
| | - Yash Nayak
- School of Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA;
| | - Christopher Mejias
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (C.M.); (G.L.B.); (V.M.M.)
| | - Grace L. Bishop
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (C.M.); (G.L.B.); (V.M.M.)
| | - Vincent M. Mellnick
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (C.M.); (G.L.B.); (V.M.M.)
| | - David H. Ballard
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; (C.M.); (G.L.B.); (V.M.M.)
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Tan DNH, Tan M, Liew H, Shen L, Ngiam KY, Chen DZ. A data-driven approach to evaluate factors affecting resident performance in cataract surgery. Int Ophthalmol 2023:10.1007/s10792-023-02730-1. [PMID: 37160586 DOI: 10.1007/s10792-023-02730-1] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 04/22/2023] [Indexed: 05/11/2023]
Abstract
PURPOSE To evaluate the operative duration and clinical performance of ophthalmology residents performing standard phacoemulsification cataract surgeries using information available from electronic health records (EHR). METHODS This is a retrospective cohort study. De-identified surgical records of all standard phacoemulsifications performed in a tertiary institution between 1st January 2015 and 8th August 2018 were retrieved from the hospital EHR. The main outcome measures were improvement in operative duration with case experience, corrected distance visual acuity (CDVA) improvement, and intra-operative complication rates. RESULTS Twelve ophthalmology residents performed a total of 1427 standard phacoemulsifications. The median operative duration was 27 min (interquartile range, 22-34 min), which improved from 31 to 24 min (before the 101st case [Group 1] versus 101st case onwards [Group 2], p < 0.001). Gradient change analysis (non-linear regression) showed significant reduction until the 100th case (p = 0.043). Older patients (0.019), worse pre-operative CDVA (0.343), and surgery performed by Group 1 (1.115) were significantly associated with operative duration above 30 min. LogMAR CDVA improved from a mean of 0.57 ± 0.52 pre-operatively to 0.10 ± 0.18 post-operatively (p < 0.001). Posterior capsule rupture (PCR) rate decreased from 4.0% [Group 1] to 2.1% [Group 2] (p = 0.096), while overall complication rate decreased from 8.9% to 3.1% (p < 0.001). CONCLUSION The median operative duration reduced consistently with surgical experience for the first 100 cases. Older patients, poorer pre-operative VA, and surgical experience of less than 100 cases were significantly associated with an operative duration above 30 min. There was a statistically significant decrease in complication rate between Group 1 and 2.
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Affiliation(s)
- Darren Ngiap Hao Tan
- Department of Ophthalmology, National University Hospital, Level 7, 1E Kent Ridge Road, Singapore, 119228, Singapore
| | - Marcus Tan
- Department of Ophthalmology, National University Hospital, Level 7, 1E Kent Ridge Road, Singapore, 119228, Singapore
| | - Hariz Liew
- Department of Ophthalmology, National University Hospital, Level 7, 1E Kent Ridge Road, Singapore, 119228, Singapore
| | - Liang Shen
- Biostatistics Unit, Yong Loo Lin School of Medicine, Singapore, Singapore
| | - Kee Yuan Ngiam
- Division of General Surgery (Endocrine and Thyroid Surgery), Department of Surgery, National University Hospital, Singapore, Singapore
| | - David Z Chen
- Department of Ophthalmology, National University Hospital, Level 7, 1E Kent Ridge Road, Singapore, 119228, Singapore.
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8
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Goenadi CJ, Chew KL, Gopal L, Chen DZ. Clinical outcome of bacterial endogenous endophthalmitis in 15 patients. Ann Acad Med Singap 2023. [DOI: 10.47102/annals-acadmedsg.2022407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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9
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Jin EY, Chen DZ. Comparison of complication rates between femtosecond laser-assisted cataract surgery and conventional phacoemulsification cataract surgery. Int J Ophthalmol 2023; 16:156-158. [PMID: 36659940 PMCID: PMC9815983 DOI: 10.18240/ijo.2023.01.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/26/2022] [Indexed: 12/30/2022] Open
Affiliation(s)
- Eric Y Jin
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - David Z Chen
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore,Department of Ophthalmology, National University Hospital, Singapore 119074, Singapore
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10
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Goenadi CJ, Chew KL, Gopal L, Chen DZ. Clinical outcome of bacterial endogenous endophthalmitis in 15 patients. Ann Acad Med Singap 2023; 52:44-47. [PMID: 36730805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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11
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Zhang LS, Ling PY, Chen Y, Chen DZ. [Progress in the effect of human epididymis protein 4 on sperm maturation]. Zhonghua Yu Fang Yi Xue Za Zhi 2022; 56:1123-1126. [PMID: 35922242 DOI: 10.3760/cma.j.cn112150-20220314-00236] [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: 06/15/2023]
Abstract
Human epididymis protein 4(HE4) is a secretory glycoprotein found in human distal epididymis epithelial cells. It is often used in the early diagnosis, efficacy evaluation and monitoring of ovarian cancer, and also has been considered as an effective serum marker for many other types of cancer. However, its function in the process of sperm maturation is not fully unknown. The maturation of sperm in epididymis is characterized by the acquisition of motility and fertilization. As a member of the whey acid protein (WAP) family, several studies proposed the importance of HE4 in the maturity of sperm in epididymis. This article reviews the effect of HE4 on spermatozoa maturation in epididymis, which provides basis for the evaluation of male reproductive ability, early detection, early diagnosis and pathogenesis of male infertility.
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Affiliation(s)
- L S Zhang
- State Key Laboratory of Reproductive Medicine of Nanjing Medical university, Nanjing 210000, China
| | - P Y Ling
- State Key Laboratory of Reproductive Medicine of Nanjing Medical university, Nanjing 210000, China
| | - Y Chen
- Research Institute for Reproductive Health and Genetic Diseases, Wuxi 214002, China
| | - D Z Chen
- Research Institute for Reproductive Health and Genetic Diseases, Wuxi 214002, China
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12
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Chen DZ, Chai C, Tan A, Ray M. Microbial patterns of Acanthamoeba keratitis at a Singapore ophthalmic referral hospital: A 5-year retrospective observational study. Ann Acad Med Singap 2021; 50:494-496. [PMID: 34195759 DOI: 10.47102/annals-acadmedsg.2020507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Affiliation(s)
- David Z Chen
- Department of Ophthalmology, National University Hospital, Singapore
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Abstract
ABSTRACT
Introduction: Teleophthalmology may assist the healthcare sector in adapting to limitations imposed on
clinical practice by a viral pandemic. A scoping review is performed in this study to assess the current
applications of teleophthalmology for its suitability to diagnose, monitor or manage ophthalmological
conditions with accuracy.
Methods: A search of PubMed was conducted for teleophthalmology-related articles published from
1 January 2018 to 4 May 2020. Only articles that focused on the use of teleophthalmology in terms of
diagnosis and management, as well as its benefits and detriments, were included. The Mixed Methods
Appraisal Tool (MMAT) was used to assess the quality of the included articles.
Results: A total of 38 articles were assessed at the full-text level. There were 2 qualitative studies and
1 quantitative randomised controlled trial, while the majority were either quantitative descriptive studies
(19, 50.0%) or quantitative non-randomised studies (16, 42.1%). Overall, 8 studies described reducing
manpower requirements, 4 described reducing direct patient–doctor contact, 17 described storage of
medical imaging and clinical data, and 9 described real-time teleconferencing. The MMAT analysis
revealed limitations in appropriate sampling strategy in both quantitative non-randomised studies (9 of
16, 56.3%) and quantitative descriptive studies (9 of 19, 47.4%). Cost-effectiveness of teleophthalmology
was not performed in any included study.
Conclusion: This current review of the various aspects of teleophthalmology describes how it may
potentially assist the healthcare sector to cope with the limitations imposed by a viral pandemic through
technology. Further research is required to evaluate the cost-effectiveness of the various strategies.
Keywords: Artificial intelligence, health informatics, ophthalmology, teleconsultation, telemedicine
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Lin HA, Chen DZ, Tan CWT. Neuro-Behçet's disease presenting as isolated intracranial hypertension. Ann Acad Med Singap 2021; 50:88-89. [PMID: 33623963 DOI: 10.47102/annals-acadmedsg.2020189] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Hazel A Lin
- Department of Ophthalmology, National University Hospital, Singapore
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15
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Chen DZ, Aquino MCD, Chng WJ, Koh VTC. Daratumumab-induced transient myopic shift and its proposed mechanisms. Clin Exp Ophthalmol 2020; 49:81-83. [PMID: 33084180 DOI: 10.1111/ceo.13874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 10/12/2020] [Accepted: 10/16/2020] [Indexed: 11/26/2022]
Affiliation(s)
- David Z Chen
- Department of Ophthalmology, National University Hospital, Singapore, Singapore
| | | | - Wee Joo Chng
- National University Cancer Institute, National University Health System, Singapore, Singapore.,Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore.,Cancer Science Institute of Singapore, National University Health System, Singapore, Singapore
| | - Victor T C Koh
- Department of Ophthalmology, National University Hospital, Singapore, Singapore
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16
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Chen DZ, Sng CCA, Sangtam T, Thomas A, Shen L, Huang PK, Cheng J. Phacoemulsification vs phacoemulsification with micro‐bypass stent implantation in primary angle closure and primary angle closure glaucoma: A randomized single‐masked clinical study. Clin Exp Ophthalmol 2020; 48:450-461. [DOI: 10.1111/ceo.13721] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 12/15/2019] [Accepted: 12/30/2019] [Indexed: 12/11/2022]
Affiliation(s)
- David Z. Chen
- Department of OphthalmologyNational University Hospital Singapore Singapore
| | - Chelvin C. A. Sng
- Department of OphthalmologyNational University Hospital Singapore Singapore
- Glaucoma ServiceMoorfields Eye Hospital London UK
- Singapore Eye Research Institute Singapore Singapore
| | - Tiakumzuk Sangtam
- Department of Ophthalmology and Visual ScienceKhoo Teck Puat Hospital Singapore Singapore
| | - Anoop Thomas
- Department of Ophthalmology and Visual ScienceKhoo Teck Puat Hospital Singapore Singapore
| | - Liang Shen
- Biostatistics Unit, Yong Loo Lin School of MedicineNational University of Singapore Singapore Singapore
| | - Philemon K. Huang
- Department of Ophthalmology and Visual ScienceKhoo Teck Puat Hospital Singapore Singapore
| | - Jason Cheng
- Department of Ophthalmology and Visual ScienceKhoo Teck Puat Hospital Singapore Singapore
- Department of OphthalmologyUniversity of New South Wales, Liverpool Hospital Sydney Australia
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Eckerdt F, Bell JB, Beauchamp EM, Clymer J, Blyth GT, Kosciuczuk EM, Ma Q, Chen DZ, Horbinski C, Goldman S, Munshi HG, Hashizume R, Platanias LC. Potent Antineoplastic Effects of Combined PI3Kα-MNK Inhibition in Medulloblastoma. Mol Cancer Res 2019; 17:1305-1315. [PMID: 30842251 PMCID: PMC6548590 DOI: 10.1158/1541-7786.mcr-18-1193] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [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: 11/10/2018] [Revised: 01/15/2019] [Accepted: 03/01/2019] [Indexed: 12/28/2022]
Abstract
Medulloblastoma is a highly malignant pediatric brain tumor associated with poor outcome. Developing treatments that target the cancer stem cell (CSC) population in medulloblastoma are important to prevent tumor relapse and induce long-lasting clinical responses. We utilized medulloblastoma neurospheres that display CSC characteristics and found activation of the PI3K/AKT pathway in sphere-forming cells. Of all class IA PI3Ks, only the PI3Kα isoform was required for sphere formation by medulloblastoma cells. Knockdown of p110α, but not p110β or p110δ, significantly disrupted cancer stem cell frequencies as determined by extreme limiting dilution analysis (ELDA), indicating an essential role for the PI3Kα catalytic isoform in medulloblastoma CSCs. Importantly, pharmacologic inhibition of the MAPK-interacting kinase (MNK) enhanced the antineoplastic effects of targeted PI3Kα inhibition in medulloblastoma. This indicates that MNK signaling promotes survival in medulloblastoma, suggesting dual PI3Kα and MNK inhibition may provide a novel approach to target and eliminate medulloblastoma CSCs. We also observed a significant reduction in tumor formation in subcutaneous and intracranial mouse xenograft models, which further suggests that this combinatorial approach may represent an efficient therapeutic strategy for medulloblastoma. IMPLICATIONS: These findings raise the possibility of a unique therapeutic approach for medulloblastoma, involving MNK targeting to sensitize medulloblastoma CSCs to PI3Kα inhibition.
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Affiliation(s)
- Frank Eckerdt
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
- Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Jonathan B Bell
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
| | - Elspeth M Beauchamp
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
- Division of Hematology/Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
- Medicine Service, Jesse Brown VA Medical Center, Chicago, Illinois
| | - Jessica Clymer
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
- Division of Hematology/Oncology/Stem Cell Transplantation, Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois
| | - Gavin T Blyth
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
| | - Ewa M Kosciuczuk
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
- Division of Hematology/Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
- Medicine Service, Jesse Brown VA Medical Center, Chicago, Illinois
| | - Quanhong Ma
- Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - David Z Chen
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
| | - Craig Horbinski
- Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Stewart Goldman
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
- Division of Hematology/Oncology/Stem Cell Transplantation, Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois
| | - Hidayatullah G Munshi
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
- Division of Hematology/Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
- Medicine Service, Jesse Brown VA Medical Center, Chicago, Illinois
- Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Rintaro Hashizume
- Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Leonidas C Platanias
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois.
- Division of Hematology/Oncology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
- Medicine Service, Jesse Brown VA Medical Center, Chicago, Illinois
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Chen DZ, Koh V, Tan M, Tan CS, Nah G, Shen L, Bhargava M, Cheng CY, Zhao P, Wong TY, Saw SM. Peripheral retinal changes in highly myopic young Asian eyes. Acta Ophthalmol 2018; 96:e846-e851. [PMID: 29575821 DOI: 10.1111/aos.13752] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [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: 05/28/2017] [Accepted: 02/08/2018] [Indexed: 11/28/2022]
Abstract
PURPOSE To determine the type and prevalence of peripheral retinal changes and its relationship with axial length (AL) in a population of young Asian adult males. METHODS This was a cross-sectional study of male subjects aged between 19 and 25 years old. High myopes [spherical equivalent refraction, (SER) < -6.00 D] were recruited and underwent further ocular investigations including dilated retinal photography and binocular indirect ophthalmoscopy by two trained ophthalmologists. The frequency of peripheral retinal changes within high myopes was correlated with axial length and also compared with a group of emmetropes (SER between -0.50 D and +1.00 D). RESULTS A total of 593 high myopes and 156 emmetropes were recruited. White without pressure (WWOP; n = 458, 46.5%) and lattice degeneration (LD; n = 109, 14.6%) were the commonest findings, and their prevalence was significantly higher among high myopes (LD, 16.9% versus 5.8%; WWOP, 57.2% versus 5.8%; both p < 0.001). Among high myopes, temporal LD was more common (71%) and 35% had more than one area in the same eye. Increasing AL was associated with LD (odds ratio 1.28, p = 0.01) and retinal holes (odd's ratio 1.44, p = 0.02) on multivariate analysis. CONCLUSION White without pressure (WWOP) and LD were the commonest peripheral retinal changes. One-third of high myopes with LD had more than one area in the same eye. Increasing AL was associated with LD and retinal holes. Studies in older adults should be conducted to develop clinical guidelines for the management of high myopes.
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Affiliation(s)
- David Z. Chen
- Vision Performance Centre; Military Medicine Institute; Singapore Singapore
- Department of Ophthalmology; National University Health System; Singapore Singapore
| | - Victor Koh
- Vision Performance Centre; Military Medicine Institute; Singapore Singapore
- Department of Ophthalmology; National University Health System; Singapore Singapore
| | - Marcus Tan
- Vision Performance Centre; Military Medicine Institute; Singapore Singapore
| | - Colin S. Tan
- National Healthcare Group Eye Institute; Tan Tock Seng Hospital; Singapore Singapore
- Fundus Image Reading Center; National Healthcare Group Eye Institute; Singapore Singapore
| | - Gerard Nah
- Vision Performance Centre; Military Medicine Institute; Singapore Singapore
| | - Liang Shen
- Biostatistics Unit; Yong Loo Lin School of Medicine; National University of Singapore; Singapore Singapore
| | - Mayuri Bhargava
- Vision Performance Centre; Military Medicine Institute; Singapore Singapore
| | - Ching-Yu Cheng
- Singapore Eye Research Institute; Singapore National Eye Centre; Singapore Singapore
| | - Paul Zhao
- Vision Performance Centre; Military Medicine Institute; Singapore Singapore
| | - Tien Yin Wong
- Singapore Eye Research Institute; Singapore National Eye Centre; Singapore Singapore
- Department of Ophthalmology; Yong Loo Lin School of Medicine; National University of Singapore; Singapore Singapore
| | - Seang-Mei Saw
- Singapore Eye Research Institute; Singapore National Eye Centre; Singapore Singapore
- Department of Ophthalmology; Yong Loo Lin School of Medicine; National University of Singapore; Singapore Singapore
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19
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Kim OV, Litvinov RI, Chen J, Chen DZ, Weisel JW, Alber MS. Compression-induced structural and mechanical changes of fibrin-collagen composites. Matrix Biol 2017; 60-61:141-156. [PMID: 27751946 PMCID: PMC5392380 DOI: 10.1016/j.matbio.2016.10.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [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: 04/30/2016] [Revised: 09/30/2016] [Accepted: 10/13/2016] [Indexed: 12/29/2022]
Abstract
Fibrin and collagen as well as their combinations play an important biological role in tissue regeneration and are widely employed in surgery as fleeces or sealants and in bioengineering as tissue scaffolds. Earlier studies demonstrated that fibrin-collagen composite networks displayed improved tensile mechanical properties compared to the isolated protein matrices. Unlike previous studies, here unconfined compression was applied to a fibrin-collagen filamentous polymer composite matrix to study its structural and mechanical responses to compressive deformation. Combining collagen with fibrin resulted in formation of a composite hydrogel exhibiting synergistic mechanical properties compared to the isolated fibrin and collagen matrices. Specifically, the composite matrix revealed a one order of magnitude increase in the shear storage modulus at compressive strains>0.8 in response to compression compared to the mechanical features of individual components. These material enhancements were attributed to the observed structural alterations, such as network density changes, an increase in connectivity along with criss-crossing, and bundling of fibers. In addition, the compressed composite collagen/fibrin networks revealed a non-linear transformation of their viscoelastic properties with softening and stiffening regimes. These transitions were shown to depend on protein concentrations. Namely, a decrease in protein content drastically affected the mechanical response of the networks to compression by shifting the onset of stiffening to higher degrees of compression. Since both natural and artificially composed extracellular matrices experience compression in various (patho)physiological conditions, our results provide new insights into the structural biomechanics of the polymeric composite matrix that can help to create fibrin-collagen sealants, sponges, and tissue scaffolds with tunable and predictable mechanical properties.
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Affiliation(s)
- O V Kim
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, United States; Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN 46556, United States
| | - R I Litvinov
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, United States
| | - J Chen
- Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, IN 46556, United States
| | - D Z Chen
- Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, IN 46556, United States
| | - J W Weisel
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, United States.
| | - M S Alber
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN 46556, United States; Department of Mathematics, University of California Riverside, CA 92521, United States; Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
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Chen H, Chen DZ, Fan S, Hong L, Wang D. SNCR De-NOx within a moderate temperature range using urea-spiked hydrazine hydrate as reductant. Chemosphere 2016; 161:208-218. [PMID: 27427778 DOI: 10.1016/j.chemosphere.2016.07.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 01/11/2016] [Revised: 05/22/2016] [Accepted: 07/04/2016] [Indexed: 05/26/2023]
Abstract
In this research, urea-spiked hydrazine hydrate solutions are used as reductants for the Selective Non-Catalytic Reduction (SNCR) De-NOx process below 650 °C. The urea concentration in the urea/hydrazine hydrate solutions is chosen through experimental and theoretical studies. To determine the mechanism of the De-NOx process, thermogravimetric analysis (TGA) of the urea/hydrazine hydrate solutions and their thermal decomposition in air and nitrogen atmospheres were studied to understand their decomposition behaviours and redox characteristics. Then a plug flow reactor (PFR) model was adopted to simulate the De-NOx processes in a pilot scale tubular reactor, and the calculated De-NOx efficiency vs. temperature profiles were compared with experimental results to support the mechanism and choose the proper reductant and its reaction temperature. Both the experimental and calculated results show that when the urea is spiked into hydrazine hydrate solution to make the urea-N content approximately 16.7%-25% of the total N content in the solution, better De-NOx efficiencies can be obtained in the temperature range of 550-650 °C, under which NH3 is inactive in reducing NOx. And it is also proved that for these urea-spiked hydrazine hydrate solutions, the hydrazine decomposition through the pathway N2H4 + M = N2H3 + H + M is enhanced to provide radical H, which is active to reduce NO. Finally, the reaction routes for SNCR De-NOx process based on urea-spiked hydrazine hydrate at the proper temperature are proposed.
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Affiliation(s)
- H Chen
- Thermal and Environmental Engineering Institute, Tongji University, 200092, Shanghai, China
| | - D Z Chen
- Thermal and Environmental Engineering Institute, Tongji University, 200092, Shanghai, China.
| | - S Fan
- Thermal and Environmental Engineering Institute, Tongji University, 200092, Shanghai, China
| | - L Hong
- Thermal and Environmental Engineering Institute, Tongji University, 200092, Shanghai, China
| | - D Wang
- Thermal and Environmental Engineering Institute, Tongji University, 200092, Shanghai, China; Institute of Energy and Environment Engineering, Shanghai University of Electric Power, 200090, China
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21
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Lee SW, Jafary-Zadeh M, Chen DZ, Zhang YW, Greer JR. Size Effect Suppresses Brittle Failure in Hollow Cu60Zr40 Metallic Glass Nanolattices Deformed at Cryogenic Temperatures. Nano Lett 2015; 15:5673-5681. [PMID: 26262592 DOI: 10.1021/acs.nanolett.5b01034] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
To harness "smaller is more ductile" behavior emergent at nanoscale and to proliferate it onto materials with macroscale dimensions, we produced hollow-tube Cu60Zr40 metallic glass nanolattices with the layer thicknesses of 120, 60, and 20 nm. They exhibit unique transitions in deformation mode with tube-wall thickness and temperature. Molecular dynamics simulations and analytical models were used to interpret these unique transitions in terms of size effects on the plasticity of metallic glasses and elastic instability.
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Affiliation(s)
- Seok-Woo Lee
- Division of Engineering and Applied Science, California Institute of Technology , 1200 E California Blvd, Pasadena, California 91125, United States
- Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut , Unit 3136, 97 North Eagleville Road, Storrs, Connecticut 06269-3136, United States
| | - Mehdi Jafary-Zadeh
- Institute of High Performance Computing, A*STAR, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - David Z Chen
- Division of Engineering and Applied Science, California Institute of Technology , 1200 E California Blvd, Pasadena, California 91125, United States
| | - Yong-Wei Zhang
- Institute of High Performance Computing, A*STAR, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - Julia R Greer
- Division of Engineering and Applied Science, California Institute of Technology , 1200 E California Blvd, Pasadena, California 91125, United States
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Gallant BM, Gu XW, Chen DZ, Greer JR, Lewis NS. Tailoring of interfacial mechanical shear strength by surface chemical modification of silicon microwires embedded in Nafion membranes. ACS Nano 2015; 9:5143-5153. [PMID: 25872455 DOI: 10.1021/acsnano.5b00468] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The interfacial shear strength between Si microwires and a Nafion membrane has been tailored through surface functionalization of the Si. Acidic (-COOH-terminated) or basic (-NH2-terminated) surface-bound functionality was introduced by hydrosilylation reactions to probe the interactions between the functionalized Si microwires and hydrophilic ionically charged sites in the Nafion polymeric side chains. Surfaces functionalized with SiOx, Si-H, or Si-CH3 were also synthesized and investigated. The interfacial shear strength between the functionalized Si microwire surfaces and the Nafion matrix was quantified by uniaxial wire pull-out experiments in an in situ nanomechanical instrument that allowed simultaneous collection of mechanical data and visualization of the deformation process. In this process, an axial load was applied to the custom-shaped top portions of individual wires until debonding occurred from the Nafion matrix. The shear strength obtained from the nanomechanical measurements correlated with the chemical bond strength and the functionalization density of the molecular layer, with values ranging from 7 MPa for Si-CH3 surfaces to ∼16-20 MPa for oxygen-containing surface functionalities. Hence surface chemical control can be used to influence the mechanical adhesion forces at a Si-Nafion interface.
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Affiliation(s)
- Betar M Gallant
- †Division of Chemistry and Chemical Engineering, ‡Division of Engineering and Applied Sciences, §The Kavli Nanoscience Institute at Caltech, and ∥The Beckman Institute at Caltech, California Institute of Technology, Pasadena, California 91125, United States
| | - X Wendy Gu
- †Division of Chemistry and Chemical Engineering, ‡Division of Engineering and Applied Sciences, §The Kavli Nanoscience Institute at Caltech, and ∥The Beckman Institute at Caltech, California Institute of Technology, Pasadena, California 91125, United States
| | - David Z Chen
- †Division of Chemistry and Chemical Engineering, ‡Division of Engineering and Applied Sciences, §The Kavli Nanoscience Institute at Caltech, and ∥The Beckman Institute at Caltech, California Institute of Technology, Pasadena, California 91125, United States
| | - Julia R Greer
- †Division of Chemistry and Chemical Engineering, ‡Division of Engineering and Applied Sciences, §The Kavli Nanoscience Institute at Caltech, and ∥The Beckman Institute at Caltech, California Institute of Technology, Pasadena, California 91125, United States
| | - Nathan S Lewis
- †Division of Chemistry and Chemical Engineering, ‡Division of Engineering and Applied Sciences, §The Kavli Nanoscience Institute at Caltech, and ∥The Beckman Institute at Caltech, California Institute of Technology, Pasadena, California 91125, United States
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Chen DZ, Koh V, Sng C, Aquino MC, Chew P. Complications and outcomes of primary phacotrabeculectomy with mitomycin C in a multi-ethnic asian population. PLoS One 2015; 10:e0118852. [PMID: 25775362 PMCID: PMC4361399 DOI: 10.1371/journal.pone.0118852] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 01/17/2015] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To determine the occurrence of intraoperative and postoperative complications up to three years after primary phacotrabeculectomy with intraoperative use of Mitomycin C (MMC) in primary open angle (POAG) and primary angle closure glaucoma (PACG) patients, and the effect of postoperative complications on surgical outcome. METHODS Retrospective review of 160 consecutive patients with POAG (n = 105) and PACG (n = 55), who underwent primary phacotrabeculectomy with MMC at the National University Hospital, Singapore, from January 1, 2008 to December 31, 2010. Data was collected using a standardized form that included patient demographic information, ocular characteristics and postoperative complications, including hypotony (defined as intraocular pressure < 6 mmHg), shallow anterior chamber (AC) and hyphema. RESULTS The mean age ± standard deviation (SD) of patients was 68.2 ± 8.2 years. No patient lost light perception during duration of follow-up. 77% of the postoperative complications occurred within the first month only. The commonest complications were hypotony (n = 41, 25.6%), hyphema (n = 16, 10.0%) and shallow AC (n = 16, 10.0%). Five patients (3.1%) required reoperation for their complications. Early hypotony (defined as hypotony < 30 days postoperatively) was an independent risk factor for surgical failure (hazard ratio [HR], 5.1; 95% CI, 1.6-16.2; p = 0.01). Hypotony with another complication was also a risk factor for surgical failure (p < 0.02). CONCLUSIONS Hypotony, hyphema and shallow AC were the commonest postoperative complications in POAG and PACG patients after phacotrabeculectomy with MMC. Most complications were transient and self-limiting. Early hypotony within the first month was a significant risk factor for surgical failure.
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Affiliation(s)
- David Z. Chen
- Department of Ophthalmology, National University Health System, Singapore, Singapore
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- * E-mail:
| | - Victor Koh
- Department of Ophthalmology, National University Health System, Singapore, Singapore
| | - Chelvin Sng
- Department of Ophthalmology, National University Health System, Singapore, Singapore
| | - Maria C. Aquino
- Department of Ophthalmology, National University Health System, Singapore, Singapore
| | - Paul Chew
- Department of Ophthalmology, National University Health System, Singapore, Singapore
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24
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Gu XW, Jafary-Zadeh M, Chen DZ, Wu Z, Zhang YW, Srolovitz DJ, Greer JR. Mechanisms of failure in nanoscale metallic glass. Nano Lett 2014; 14:5858-5864. [PMID: 25198652 DOI: 10.1021/nl5027869] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The emergence of size-dependent mechanical strength in nanosized materials is now well-established, but no fundamental understanding of fracture toughness or flaw sensitivity in nanostructures exists. We report the fabrication and in situ fracture testing of ∼70 nm diameter Ni-P metallic glass samples with a structural flaw. Failure occurs at the structural flaw in all cases, and the failure strength of flawed samples was reduced by 40% compared to unflawed samples. We explore deformation and failure mechanisms in a similar nanometallic glass via molecular dynamics simulations, which corroborate sensitivity to flaws and reveal that the structural flaw shifts the failure mechanism from shear banding to cavitation. We find that failure strength and deformation in amorphous nanosolids depend critically on the presence of flaws.
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Affiliation(s)
- X Wendy Gu
- Division of Chemistry and Chemical Engineering and ‡Division of Engineering and Applied Science, California Institute of Technology , 1200 E. California Blvd., Pasadena, California 91125, United States
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25
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Song XD, Xue XY, Chen DZ, He PJ, Dai XH. Application of biochar from sewage sludge to plant cultivation: Influence of pyrolysis temperature and biochar-to-soil ratio on yield and heavy metal accumulation. Chemosphere 2014; 109:213-20. [PMID: 24582602 DOI: 10.1016/j.chemosphere.2014.01.070] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [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: 10/15/2013] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 05/24/2023]
Abstract
Applying biochar products from sewage sludge (SS) pyrolysis as soil amendment for plant cultivation was investigated in this study with special attention paid to heavy metal accumulation in the plants when pyrolysis temperature and biochar-to-soil mass ratio (C:S) were changed. Biochar obtained at four different temperatures were adopted as soil amendment for Allium sativum L. garlic plant cultivation. Experimental results revealed that biochars were rich in nutrient contents and they improved garlic yields. Although contents of heavy metals including As, Zn, Pb, Ni, Cd, Cr and Cu, etc. were elevated in the biochars compared to local soil, they fell within the acceptable limits for land application and SS is a suitable biochar resource, especially biochar produced at 450°C had rich micropores, relatively stable functional groups in structure and rugged surface to contact well with soil, conducive to its usage as a biochar. The garlic grew faster when planted in the biochar-amended soil and had higher final dry matter yields than those planted in the reference soil, especially biochar produced at 450°C corresponding to the highest final yields. The C:S ratio related to the highest garlic yields changed when the pyrolysis temperature was changed and this ratio was 1:4 for the biochar produced at 450°C. General heavy metal accumulation in the garlic occurred only for the most enriched Zn and Cu, and mainly in the roots & bulbs; in addition this bioaccumulation was increasing as leaching from biochar increased but not increasing with C:S ratio. The garlic planted in soil amended with biochar of 450°C contained the lowest level of heavy metals compared to other biochars. Those results indicated that heavy metal accumulation in plants can be inhibited through proper pyrolysis temperature choice and prevention of heavy metal leaching from the SS biochar.
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Affiliation(s)
- X D Song
- Thermal & Environmental Engineering Institute, Tongji University, 200092 Shanghai, China
| | - X Y Xue
- Thermal & Environmental Engineering Institute, Tongji University, 200092 Shanghai, China
| | - D Z Chen
- Thermal & Environmental Engineering Institute, Tongji University, 200092 Shanghai, China.
| | - P J He
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 200092 Shanghai, China
| | - X H Dai
- National Engineering Research Centre for Urban Pollution Control, College of Environmental Science and Engineering, Tongji University, 200092 Shanghai, China
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Yang L, Yang J, Liu KF, Qin B, Chen DZ. A combined compensation method for the output voltage of an insulated core transformer power supply. Rev Sci Instrum 2014; 85:063302. [PMID: 24985809 DOI: 10.1063/1.4884340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
An insulated core transformer (ICT) power supply is an ideal high-voltage generator for irradiation accelerators with energy lower than 3 MeV. However, there is a significant problem that the structure of the segmented cores leads to an increase in the leakage flux and voltage differences between rectifier disks. A high level of consistency in the output of the disks helps to achieve a compact structure by improving the utilization of both the rectifier components and the insulation distances, and consequently increase the output voltage of the power supply. The output voltages of the disks which are far away from the primary coils need to be improved to reduce their inhomogeneity. In this study, by investigating and comparing the existing compensation methods, a new combined compensation method is proposed, which increases the turns on the secondary coils and employs parallel capacitors to improve the consistency of the disks, while covering the entire operating range of the power supply. This method turns out to be both feasible and effective during the development of an ICT power supply. The non-uniformity of the output voltages of the disks is less than 3.5% from no-load to full-load, and the power supply reaches an output specification of 350 kV/60 mA.
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Affiliation(s)
- L Yang
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - J Yang
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - K F Liu
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - B Qin
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - D Z Chen
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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Au Eong DTM, Chen DZ, Au Eong KG. Detailed drawing of a dislocated intraocular lens visualised by a patient. Clin Exp Ophthalmol 2014; 42:893-4. [DOI: 10.1111/ceo.12348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Accepted: 04/15/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Denise TM Au Eong
- Singapore International Eye Cataract Retina Centre; Mount Elizabeth Medical Centre and Farrer Park Medical Centre; Singapore
| | - David Z Chen
- Yong Loo Lin School of Medicine; National University of Singapore; Singapore
| | - Kah-Guan Au Eong
- Singapore International Eye Cataract Retina Centre; Mount Elizabeth Medical Centre and Farrer Park Medical Centre; Singapore
- Department of Ophthalmology and Visual Sciences; Khoo Teck Puat Hospital; Singapore
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Chen DZ, Jang D, Guan KM, An Q, Goddard WA, Greer JR. Nanometallic glasses: size reduction brings ductility, surface state drives its extent. Nano Lett 2013; 13:4462-4468. [PMID: 23978318 DOI: 10.1021/nl402384r] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report tensile experiments on Ni80P20 metallic glass samples fabricated via a templated electroplating process and via focused ion beam milling, which differed only in their surface energy states: Ga-ion-irradiated and as-electroplated. Molecular dynamics simulations on similar Ni80Al20 systems corroborate the experimental results, which suggest that the transition from brittle to ductile behavior is driven by sample size, while the extent of ductility is driven by surface state.
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Affiliation(s)
- D Z Chen
- Division of Engineering and Applied Sciences and ‡Department of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91106, United States
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Xiao K, Zhou B, Hu XS, Chen DZ. WE-C-108-06: Accelerating Collapsed Cone Convolution/Superposition Dose Calculation On GPU Using Spatial Decomposition. Med Phys 2013. [DOI: 10.1118/1.4815529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Habegger L, Balasubramanian S, Chen DZ, Khurana E, Sboner A, Harmanci A, Rozowsky J, Clarke D, Snyder M, Gerstein M. VAT: a computational framework to functionally annotate variants in personal genomes within a cloud-computing environment. ACTA ACUST UNITED AC 2012; 28:2267-9. [PMID: 22743228 DOI: 10.1093/bioinformatics/bts368] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
UNLABELLED The functional annotation of variants obtained through sequencing projects is generally assumed to be a simple intersection of genomic coordinates with genomic features. However, complexities arise for several reasons, including the differential effects of a variant on alternatively spliced transcripts, as well as the difficulty in assessing the impact of small insertions/deletions and large structural variants. Taking these factors into consideration, we developed the Variant Annotation Tool (VAT) to functionally annotate variants from multiple personal genomes at the transcript level as well as obtain summary statistics across genes and individuals. VAT also allows visualization of the effects of different variants, integrates allele frequencies and genotype data from the underlying individuals and facilitates comparative analysis between different groups of individuals. VAT can either be run through a command-line interface or as a web application. Finally, in order to enable on-demand access and to minimize unnecessary transfers of large data files, VAT can be run as a virtual machine in a cloud-computing environment. AVAILABILITY AND IMPLEMENTATION VAT is implemented in C and PHP. The VAT web service, Amazon Machine Image, source code and detailed documentation are available at vat.gersteinlab.org.
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Affiliation(s)
- Lukas Habegger
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA.
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Sboner A, Habegger L, Pflueger D, Terry S, Chen DZ, Rozowsky JS, Tewari AK, Kitabayashi N, Moss BJ, Chee MS, Demichelis F, Rubin MA, Gerstein MB. FusionSeq: a modular framework for finding gene fusions by analyzing paired-end RNA-sequencing data. Genome Biol 2010; 11:R104. [PMID: 20964841 PMCID: PMC3218660 DOI: 10.1186/gb-2010-11-10-r104] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 08/12/2010] [Accepted: 10/21/2010] [Indexed: 12/03/2022] Open
Abstract
We have developed FusionSeq to identify fusion transcripts from paired-end RNA-sequencing. FusionSeq includes filters to remove spurious candidate fusions with artifacts, such as misalignment or random pairing of transcript fragments, and it ranks candidates according to several statistics. It also has a module to identify exact sequences at breakpoint junctions. FusionSeq detected known and novel fusions in a specially sequenced calibration data set, including eight cancers with and without known rearrangements.
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Affiliation(s)
- Andrea Sboner
- Program in Computational Biology and Bioinformatics, Yale University, 300 George Street, New Haven, CT 06511, USA.
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Zhou B, Hu XS, Chen DZ, Yu C. WE-D-303A-09: A Multi-FPGA Accelerator for Dose Calculation in Radiation Therapy. Med Phys 2009. [DOI: 10.1118/1.3182536] [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: 11/07/2022] Open
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Zhao DF, Chen DZ, Lv JS, Lang R, Jin ZK, Qing H. Establishment of an animal model of biliary ischemic stenosis with clamping in mice. Transplant Proc 2008; 40:1303-5. [PMID: 18589092 DOI: 10.1016/j.transproceed.2008.01.079] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 01/16/2008] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The objective of this study was to explore a method to establish biliary ischemic stenosis in mice. METHODS After the optimal time of biliary ischemia was determined, 20 Kunming mice were equally divided into 2 groups. In the experimental group a 0.4-cm length of common bile duct was clamped for 90 minutes with 2 micro-vessel clamps (width = 0.1 cm). The common bile duct was not clamped in the control group. Twenty-one days later, biliary tract visualization was performed in all mice. Blood samples were collected from the inferior vena cava to determine the serum levels of total bilirubin (TBIL) and alanine aminotransferase (ALT). Meanwhile, samples of the common bile duct and liver tissue were extracted for microscopic examination to observe morphological changes. RESULTS In the experimental group, obvious dilatation of the common bile duct appeared over the clamp site. There was no dilatation of the common bile duct in the control group. Twenty-one days later, serum levels of TBIL and ALT were significantly higher among the experimental compared with the control group. Microscopic examination showed that the part of common bile duct at the clamp site was significantly expanded, with a smaller or occluded bile duct lumen necrotic mucosa with determination, and tubular wall with fibrosis and excrustation. A few dead liver cells and many inflammatory cells were observed in liver tissue samples. CONCLUSIONS A biliary ischemic stenosis model was established using a clamping method in mice, which may provide a reliable technique for basic and clinical research into mechanisms of biliary ischemic stenosis after liver transplantation.
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Affiliation(s)
- D F Zhao
- Department of Hepatobiliary Surgery, Chaoyang Hospital Capital University of Medical Sciences, Beijing, China
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Yang YJ, Chen DZ, Li LX, Kou JT, Lang R, Jin ZK, Han DD, He Q. Sirolimus-based immunosuppressive therapy in liver transplant recipient with tacrolimus-related chronic renal insufficiency. Transplant Proc 2008; 40:1541-4. [PMID: 18589147 DOI: 10.1016/j.transproceed.2008.01.081] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 11/11/2007] [Accepted: 01/25/2008] [Indexed: 11/15/2022]
Abstract
BACKGROUND While providing potent immunosuppression for liver transplant recipients, calcineurin inhibitors (CNI) exhibit nephrotoxicity as a major side effect. The purpose of this study was to evaluate the safety and efficacy of conversion from CNI to sirolimus (SRL) among liver transplant recipients with CNI-induced chronic nephrotoxicity. METHODS Between January 2004 and June 2005, we performed conversion in 16 recipients after a median period of 8.5 months after liver transplantation. The indication for conversion was CNI-related nephrotoxicity with a serum creatinine (sCr) value >132.6 umol/L. Renal function was measured before and after conversion to SRL. Clinical and laboratory data related to the clinical course of the patients were recorded to investigate the safety and efficacy of conversion. RESULTS Sixteen patients were converted to SRL after developing nephrotoxicity. Their renal function improved gradually after conversion. The levels of sCr decreased significantly within the first 30 days (164.1 +/- 12.48 micromol/L to 130.1 +/- 5.573 micromol/L), and over the next 60 days after conversion (97.86 +/- 11.69 micromol/L to 90.7 +/- 8.95 micromol/L) (P < .01). Similarly, the mean glomerular filtration rate (GFR) increased significantly during the same period. Four recipients experienced hypercholesterolemia, 1 with ankle edema, and 1 with acute rejection. The median follow-up was 2.4 years. No patient discontinued SRL due to side effects. No patient needed dialysis or kidney transplantation during the study period. CONCLUSIONS SRL is a safe, effective replacement agent as primary immunosuppressive therapy following withdrawal of CNIs in liver transplant recipients with CNI-induced chronic nephrotoxicity.
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Affiliation(s)
- Y J Yang
- Beijing Chaoyang Hospital, Capital University of Medical Science/Beijing Organ Transplantation Center, Beijing, China
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Provance DW, Addison EJ, Wood PR, Chen DZ, Silan CM, Mercer JA. Myosin-Vb functions as a dynamic tether for peripheral endocytic compartments during transferrin trafficking. BMC Cell Biol 2008; 9:44. [PMID: 18687135 PMCID: PMC2533098 DOI: 10.1186/1471-2121-9-44] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Accepted: 08/07/2008] [Indexed: 12/14/2022] Open
Abstract
Background Myosin-Vb has been shown to be involved in the recycling of diverse proteins in multiple cell types. Studies on transferrin trafficking in HeLa cells using a dominant-negative myosin-Vb tail fragment suggested that myosin-Vb was required for recycling from perinuclear compartments to the plasma membrane. However, chemical-genetic, dominant-negative experiments, in which myosin-Vb was specifically induced to bind to actin, suggested that the initial hypothesis was incorrect both in its site and mode of myosin-Vb action. Instead, the chemical-genetic data suggested that myosin-Vb functions in the actin-rich periphery as a dynamic tether on peripheral endosomes, retarding transferrin transport to perinuclear compartments. Results In this study, we employed both approaches, with the addition of overexpression of full-length wild-type myosin-Vb and switching the order of myosin-Vb inhibition and transferrin loading, to distinguish between these hypotheses. Overexpression of full-length myosin-Vb produced large peripheral endosomes. Chemical-genetic inhibition of myosin-Vb after loading with transferrin did not prevent movement of transferrin from perinuclear compartments; however, virtually all myosin-Vb-decorated particles, including those moving on microtubules, were halted by the inhibition. Overexpression of the myosin-Vb tail caused a less-peripheral distribution of early endosome antigen-1 (EEA1). Conclusion All results favored the peripheral dynamic tethering hypothesis.
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Tang P, Zhao YC, Chen DZ, Xia FY. Volatility of heavy metals during incineration of tannery sludge in the presence of chlorides and phosphoric acid. Waste Manag Res 2008; 26:369-376. [PMID: 18727329 DOI: 10.1177/0734242x08092024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Knowledge of the behaviour of heavy metals in the combustion process is a most important factor in selecting disposal alternatives for waste materials. Accordingly, in this work, the vaporization behaviour of highly concentrated heavy metals (Pb, Zn, Cu and Cr) in tannery sludge were investigated experimentally. The sludge was spiked with various chlorine compounds (i.e. PVC, FeCl3, CaCl2 and NaCl) and pre-treated with phosphoric acid in order to evaluate the capacity of enhancement and weakening of the volatility of the heavy metals contained in tannery sludge. The experimental results show that the vaporization percentages increased with increasing ratio of Cl/sludge and temperature, and the accelerating and increasing effect of the addition of chlorides on the vaporization percentage of heavy metals was dependent on the release capacity of chlorine radicals. The vaporization percentages of lead and zinc increased by 15-20%, whereas those of copper and chromium increased by only about 3 and 10% at 800 degrees C. However, heavy metals were not expected to be completely released in the combustion process in spite of the high ratio of Cl/sludge. Alternately, heavy metals contained in tannery sludge can be immobilized effectively by pre-treatment with phosphoric acid. When the 85% phosphoric acid accounted for 10% of dry basis of tannery sludge, the phosphate-treated sludge showed the lowest vaporization percentage of about 3-15% with formation of Ca18Cu3(PO4)14, Ca9Cr(PO4)7, Ca19Zn2(PO4)14 and PbMgP2O7 in the bottom ash.
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Affiliation(s)
- P Tang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Engineering, Tongji University, Shanghai, China.
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Roedersheimer K, Chen DZ, Luan S, Xing L. SU-FF-T-105: The Impact of Multileaf Collimator Rotation in IMRT Planning. Med Phys 2005. [DOI: 10.1118/1.1997776] [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: 11/07/2022] Open
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Wang C, Luan S, Chen DZ, Hu X, Yu C. SU-FF-T-97: A Generalized MLC Segmentation Algorithm for Step-And-Shoot IMRT with No Tongue-And-Groove Error. Med Phys 2005. [DOI: 10.1118/1.1997768] [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: 11/07/2022] Open
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Chen DZ, Qi M, Auborn KJ, Carter TH. Indole-3-carbinol and diindolylmethane induce apoptosis of human cervical cancer cells and in murine HPV16-transgenic preneoplastic cervical epithelium. J Nutr 2001; 131:3294-302. [PMID: 11739883 DOI: 10.1093/jn/131.12.3294] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [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: 11/15/2022] Open
Abstract
Dietary indole-3-carbinol (I3C) has clinical benefits for both cervical cancer and laryngeal papillomatosis, and causes apoptosis of breast cancer cells in vitro. We asked whether I3C and its major acid-catalyzed condensation product diindolylmethane (DIM), which is produced in the stomach after consumption of cruciferous vegetables, could induce apoptosis of cervical cancer cell lines. We also asked whether this effect could be observed in vivo. In vitro, both I3C and DIM caused accumulation of DNA strand breaks in three cervical cancer cell lines. Induction of apoptosis was confirmed by nuclear morphology, nucleosome leakage, altered cytoplasmic membrane permeability and caspase 3 activation. Neither I3C nor DIM caused apoptotic changes in normal human keratinocytes. In C33A cervical cancer cells, DIM was more potent than I3C [dose at which the number of viable cells was 50% of that in untreated cultures (LD(50)) = 50-60 micromol/L for DIM and 200 micromol/L for I3C in a mitochondrial function assay] and faster acting. Furthermore, I3C reduced Bcl-2 protein in a time- and dose-dependent manner. In HPV16-transgenic mice, which develop cervical cancer after chronic estradiol exposure, apoptotic cells were detected in cervical epithelium by TdT-mediated dUTP nick-end labeling staining and by immunohistochemical staining of active caspase 3 only in mice exposed to 17beta-estradiol (E2) and fed I3C. Rare apoptotic cells were also observed by hematoxylin and eosin staining in the spinous layer of the cervical epithelium in both control and transgenic mice. Estradiol reduced the percentage of these late-stage apoptotic cells in the cervical epithelium of transgenic, E2-treated mice, but this reduction was prevented by I3C. These data confirm the proapoptotic action of I3C on transformed cells in vitro, extend the observations to cervical cancer cells and to DIM and show for the first time that dietary I3C results in increased apoptosis in target tissues in vivo.
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Affiliation(s)
- D Z Chen
- North Shore-Long Island Jewish Research Institute, Manhasset, NY 11030, USA
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Abstract
Theoretical results and practical experience indicate that feedforward networks can approximate a wide class of functional relationships very well. This property is exploited in modeling chemical processes. Given finite and noisy training data, it is important to encode the prior knowledge in neural networks to improve the fit precision and the prediction ability of the model. In this paper, as to the three-layer feedforward networks and the monotonic constraint, the unconstrained method, Joerding's penalty function method, the interpolation method, and the constrained optimization method are analyzed first. Then two novel methods, the exponential weight method and the adaptive method, are proposed. These methods are applied in simulating the true boiling point curve of a crude oil with the condition of increasing monotonicity. The simulation experimental results show that the network models trained by the novel methods are good at approximating the actual process. Finally, all these methods are discussed and compared with each other.
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Affiliation(s)
- C W Chen
- Department of Chemical Engineering, Zhejiang University, Hangzhou, People's Republic of China
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Abstract
Candida glycerinogenes, an osmotolerant yeast isolated from a natural sample in an environment of high osmotic pressure, had a modest sugar-tolerance and an extremely high glycerol productivity. The optimum conditions for glycerol formation by C. glycerinogenes were a temperature of 29-33 degrees C and a pH of 4-6. The optimum medium for glycerol production consisted of 230-250 g glucose/l, 2 g urea/l and 5 ml corn steep liquor/l (55-65 mg phosphates/l); the pH was not adjusted. The highest yield of glycerol was 64.5% (w/w) based on consumed glucose from 240 g glucose/l, and the highest concentration of glycerol was 137 g/l from 260 g glucose/l. These results were obtained by using a 30-l agitated fermentor under optimal fermentation conditions. In ten batch-fermentations carried out in a 50,000-l airlift fermentor, an average yield of glycerol of 50.67% (w/w) and an average glycerol concentration of 121.9 g/l were obtained from an average 240.6 g glucose/l.
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Affiliation(s)
- J Zhuge
- Research Center of Industrial Microorganisms and Research and Design Center of Glycerol Fermentation, School of Biotechnology, South-Yangtze University, Wuxi, China.
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Meng Q, Qi M, Chen DZ, Yuan R, Goldberg ID, Rosen EM, Auborn K, Fan S. Suppression of breast cancer invasion and migration by indole-3-carbinol: associated with up-regulation of BRCA1 and E-cadherin/catenin complexes. J Mol Med (Berl) 2001; 78:155-65. [PMID: 10868478 DOI: 10.1007/s001090000088] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Indole-3-carbinol (I3C) is a compound occurring naturally in cruciferous vegetables and has been indicated as a promising agent in preventing breast cancer development and progression. In the present study we have investigated the effect of I3C on the cell migration and invasion behavior in estrogen receptor positive MCF-7 and estrogen receptor negative MDA-MB-468 human breast cancer cell lines. Both MCF-7 and MDA-MB-468 were poorly invasive cell lines and exhibited modest invasion and migration capacity in the presence of fibronectin as the chemoattractant. I3C (50 or 100 microM) elicited a significant inhibition of in vitro cell adhesion, migration, and invasion as well as in vivo lung metastasis formation in both cell lines. I3C also suppressed the 17beta-estradiol stimulated migration and invasion in estrogen-responsive MCF-7 cells. These results indicate that anti-invasion and antimigration activities of I3C occur via estrogen-independent and estrogen-dependent pathways. Moreover, I3C significantly caused a dose-dependent increase in E-cadherin, three major catenins (alpha, beta, and gamma-catenin) and BRCA1 expression. Our current finding is the first demonstration that I3C can activate the function of invasion suppressor molecules associated with the suppression of invasion and migration in breast cancer cells. Thus, clinical application of I3C may contribute to the potential benefit for suppression of breast cancer invasion and metastasis.
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Affiliation(s)
- Q Meng
- Department of Radiation Oncology, Long Island Jewish Medical Center, The Long Island Campus for the Albert Einstein College of Medicine, New Hyde Park, New York 11042, USA
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Chen DZ, Cui H. [Analysis of multi-wavelength overlapping chromatographic data by orthogonal projection resolution]. Se Pu 2000; 18:100-3. [PMID: 12541580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023] Open
Abstract
Orthogonal projection resolution(OPR) has been proved to be a high performance chromatographic data processing technique. In this paper, it is applied to the resolution of multi-wavelength chromatographic overlapping peaks. When the highest number of degree of overlapping in chromatogram is less than or equal to the number of wavelengths used, a real resolved chromatogram can be completely obtained from multi-wavelength chromatographic overlapping peaks by this method. When based on dual wavelength chromatographic data analysis, a new method, namely dual wavelength characteristic information analysis (DWCI), used for the base line correction, determination of number of components and region of pure components signal. Analysis of overlapping cases of every components in the overlapping chromatogram is also proposed. DWCI has been successfully used for the analysis of overlapping chromatogram with dual peaks of three components and with single peak of two components. But based on single wavelength chromatographic data, the analysis of these overlapping peaks is a very difficult and complicated problem.
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Affiliation(s)
- D Z Chen
- Department of Chemistry, Huaihua Teacher's College, Huaihua 418008, China.
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Chen DZ, Patel DV, Hackbarth CJ, Wang W, Dreyer G, Young DC, Margolis PS, Wu C, Ni ZJ, Trias J, White RJ, Yuan Z. Actinonin, a naturally occurring antibacterial agent, is a potent deformylase inhibitor. Biochemistry 2000; 39:1256-62. [PMID: 10684604 DOI: 10.1021/bi992245y] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.0] [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: 11/30/2022]
Abstract
Peptide deformylase (PDF) is essential in prokaryotes and absent in mammalian cells, thus making it an attractive target for the discovery of novel antibiotics. We have identified actinonin, a naturally occurring antibacterial agent, as a potent PDF inhibitor. The dissociation constant for this compound was 0.3 x 10(-)(9) M against Ni-PDF from Escherichia coli; the PDF from Staphylococcus aureus gave a similar value. Microbiological evaluation revealed that actinonin is a bacteriostatic agent with activity against Gram-positive and fastidious Gram-negative microorganisms. The PDF gene, def, was placed under control of P(BAD) in E. coli tolC, permitting regulation of PDF expression levels in the cell by varying the external arabinose concentration. The susceptibility of this strain to actinonin increases with decreased levels of PDF expression, indicating that actinonin inhibits bacterial growth by targeting this enzyme. Actinonin provides an excellent starting point from which to derive a more potent PDF inhibitor that has a broader spectrum of antibacterial activity.
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Affiliation(s)
- D Z Chen
- Versicor, Inc., Fremont, California 94555, USA
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Jin L, Qi M, Chen DZ, Anderson A, Yang GY, Arbeit JM, Auborn KJ. Indole-3-carbinol prevents cervical cancer in human papilloma virus type 16 (HPV16) transgenic mice. Cancer Res 1999; 59:3991-7. [PMID: 10463597] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Mice that express transgenes for human papillomavirus type 16 under a keratin 14 promoter (K14-HPV16 mice) develop cervical cancer when they are given 17beta-estradiol chronically. We asked whether the antiestrogenic phytochemical indole-3-carbinol (I3C), found in cruciferous vegetables, administered at physiological doses, would prevent the cervical-vaginal cancer that is promoted in these mice by high doses of estrogen. We compared mice that were fed a control diet with those that were fed a diet supplemented with 2000 ppm I3C. In the group fed the control diet, at a dose of estradiol of 0.125 mg per 60-day release, 19 of 25 transgenic mice developed cervical-vaginal cancer within 6 months, and the remainder had dysplasia. Only 2 mice of 24 in the group fed the I3C supplemented diet developed cancer, and the remainder had dysplasia or hyperplasia. I3C reduced dysplasia in the nontransgenic mice. Similar results were obtained at a higher dose of estradiol (0.250 mg per 60-day release), and I3C helped to prevent morbidity associated with retention of fluid in the bladder that frequently occurred with the higher estradiol dose. Additionally, I3C appeared to reduce skin cancer in transgenic mice. These data indicate that I3C is a useful preventive for cervical-vaginal cancer and, possibly, other cancers with a papillomavirus component.
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Affiliation(s)
- L Jin
- Department of Otolaryngology, Long Island Jewish Medical Center, The Long Island Campus of Albert Einstein College of Medicine, New Hyde Park, New York 11040, USA
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Yuan F, Chen DZ, Liu K, Sepkovic DW, Bradlow HL, Auborn K. Anti-estrogenic activities of indole-3-carbinol in cervical cells: implication for prevention of cervical cancer. Anticancer Res 1999; 19:1673-80. [PMID: 10470100] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND Cervical cancer constitutes the second most common cancer in women. Estrogen promotes development of cervical cancer in cells infected with high risk human papillomaviruses (HPVs). We asked whether the phytochemical indole-3-carbinol (I3C) has anti-estrogenic activities in cervical cells with the goal of preventing cancer in HPV infected cells. MATERIALS AND METHODS Using the cervical cancer cell line CaSki, we evaluated expression of HPV and cytochrome p450 (CYP) enzymes by Northern, RNase protection or quantitative RT-PCR. I3C binding to estrogen receptor was measured by competition with estradiol. Estrogen metabolites were measured by gas chromarography-mass spectrometry (GC-MS). RESULTS Estradiol increased expression of HPV oncogenes whereas I3C and the estrogen metabolite 2-hydroxyestrone (2-OHE) abrogated the estrogen-increased expression of HPV oncogenes. Both I3C and 2-OHE competed with estradiol for estrogen receptor binding. I3C enhanced gene expression of CYP enzymes responsible for 2-hydroxylation of estrogen, and induced the formation of 2-OHE. CONCLUSION I3C has anti-estrogenic activities which should prevent cancer in cervical cells.
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MESH Headings
- Anticarcinogenic Agents/pharmacology
- Binding, Competitive
- Carcinoma, Squamous Cell/enzymology
- Carcinoma, Squamous Cell/pathology
- Carcinoma, Squamous Cell/prevention & control
- Carcinoma, Squamous Cell/virology
- Cervix Uteri/drug effects
- Cervix Uteri/enzymology
- Cervix Uteri/virology
- Cytochrome P-450 CYP1A1/biosynthesis
- Cytochrome P-450 CYP1A1/genetics
- Cytochrome P-450 CYP1A2/biosynthesis
- Cytochrome P-450 CYP1A2/genetics
- Cytochrome P-450 Enzyme System/biosynthesis
- Enzyme Induction/drug effects
- Estradiol/pharmacology
- Estrogen Antagonists/pharmacology
- Female
- Gene Expression Regulation, Neoplastic/drug effects
- Gene Expression Regulation, Viral/drug effects
- Humans
- Hydroxyestrones/pharmacology
- Indoles/pharmacology
- Neoplasm Proteins/biosynthesis
- Oncogene Proteins, Viral/biosynthesis
- Oncogene Proteins, Viral/genetics
- Oncogenes/drug effects
- Papillomaviridae/genetics
- Papillomaviridae/pathogenicity
- Papillomaviridae/physiology
- Papillomavirus E7 Proteins
- Papillomavirus Infections/enzymology
- Papillomavirus Infections/pathology
- RNA, Messenger/biosynthesis
- RNA, Neoplasm/biosynthesis
- RNA, Viral/biosynthesis
- Receptors, Estrogen/drug effects
- Receptors, Estrogen/metabolism
- Repressor Proteins
- Reverse Transcriptase Polymerase Chain Reaction
- Tumor Cells, Cultured
- Tumor Virus Infections/enzymology
- Tumor Virus Infections/pathology
- Tumor Virus Infections/virology
- Uterine Cervical Neoplasms/enzymology
- Uterine Cervical Neoplasms/pathology
- Uterine Cervical Neoplasms/prevention & control
- Uterine Cervical Neoplasms/virology
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Affiliation(s)
- F Yuan
- Long Island Jewish Medical Center, Albert Einstein College of Medicine, Department of Otolaryngology, New Hyde Park, NY 11040, USA
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49
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Huang ZY, Liao CX, Chen DZ. [Effect of radix Salviae miltiorrhizae on production of free radical products from lung during cardiopulmonary bypass operation]. Zhongguo Zhong Xi Yi Jie He Za Zhi 1996; 16:451-3. [PMID: 9387742] [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: 02/05/2023]
Abstract
Thirty patients of heart valve replacement were randomly divided into two groups, one as Radix Salviae Miltiorrhizae (RSM) treatment group and the other as control group. Blood samples were taken from right atrium (RA) and left atrium (LA) before cardiopulmonary bypass operation (CPB) and 10 min, 45 min, 2 hours, 6 hours after the removal of the aortic cross-clamp to observe the level of peroxidation product and the changes in leucocyte count. The results showed that the number of leucocyte in LA was smaller than that in RA and the amount of peroxidation product in LA was higher than that in RA (P < 0.01-0.05) during the early phase of the lung reperfusion in control group. There was no significant difference (P > 0.05) in the amount of peroxidation product and the number of leucocyte between LA and RA in RSM treatment group. The results demonstrated that RSM could markedly prevent the lung leucocyte aggregation and reduce the production of lung free radical products. It suggested that the effect of RSM of reducing the production of lung free radical products was related to its effect of preventing the lung leucocyte aggregation.
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Affiliation(s)
- Z Y Huang
- Cardiovascular Surgery Department, Affiliated Union Hospital, Fujian Medical College, Fuzhou
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50
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Abstract
Pharmacological characteristics of [3H]taurine release evoked by nitric oxide (NO) were investigated using mouse cerebral cortical neurons in primary culture. NO generators such as S-nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside (SNP) dose-dependently increased [3H]taurine release from neurons. Such stimulatory effects of NO generators were completely abolished by hemoglobin, a NO radical scavenger, indicating that these [3H]taurine releases might be due to NO liberated from SNAP and SNP. Sodium withdrawal from incubation buffer significantly inhibited the SNAP- and SNP-induced [3H]taurine releases, whereas the removal of calcium showed no alterations in the [3H]taurine release evoked by NO generators. Beta-Alanine and guanidinoethane sulfonate, inhibitors of carrier-mediated taurine transport system, inhibited the SNAP- and SNP-evoked releases of [3H]taurine in a dose-dependent manner. These results indicate that the NO-evoked [3H]taurine release from cerebral cortical neurons is mediated by the reverse process of sodium-dependent carrier-mediated taurine transport system.
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Affiliation(s)
- D Z Chen
- Department of Pharmacology, Kyoto Prefectural University of Medicine, Japan
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