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Su N, Wang J, Zhang H, Jin H, Miao B, Zhao J, Liu X, Li C, Wang X, Yang N. Identification and clinical validation of the role of anoikis-related genes in diabetic foot. Int Wound J 2024; 21:e14771. [PMID: 38468369 PMCID: PMC10928261 DOI: 10.1111/iwj.14771] [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: 11/22/2023] [Accepted: 01/28/2024] [Indexed: 03/13/2024] Open
Abstract
This study aims to investigate the role of anoikis-related genes in diabetic foot (DF) by utilizing bioinformatics analysis to identify key genes associated with anoikis in DF. We selected the GEO datasets GSE7014, GSE80178 and GSE68183 for the extraction and analysis of differentially expressed anoikis-related genes (DE-ARGs). GO analysis and KEGG analysis indicated that DE-ARGs in DF were primarily enriched in apoptosis, positive regulation of MAPK cascade, anoikis, focal adhesion and the PI3K-Akt signalling pathway. Based on the LASSO and SVM-RFE algorithms, we identified six characteristic genes. ROC curve analysis revealed that these six characteristic genes had an area under the curve (AUC) greater than 0.7, indicating good diagnostic efficacy. Expression analysis in the validation set revealed downregulation of CALR in DF, consistent with the training set results. GSEA results demonstrated that CALR was mainly enriched in blood vessel morphogenesis, endothelial cell migration, ECM-receptor interaction and focal adhesion. The HPA database revealed that CALR was moderately enriched in endothelial cells, and CALR was found to interact with 63 protein-coding genes. Functional analysis with DAVID suggested that CALR and associated genes were enriched in the phagosome component. CALR shows promise as a potential marker for the development and treatment of DF.
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Affiliation(s)
- Nan Su
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Jiwei Wang
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Hengrui Zhang
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Haoyong Jin
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Baojian Miao
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Jiangli Zhao
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Xuchen Liu
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Chao Li
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Xinyu Wang
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Ning Yang
- Department of Neurosurgery, Qilu Hospital, Cheeloo College of Medicine and Institute of Brain and Brain‐Inspired ScienceShandong UniversityJinanChina
- School of Medicine, Cheeloo College of MedicineShandong UniversityJinanChina
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Miao B, Feder L, Shrock JE, Milchberg HM. Phase front retrieval and correction of Bessel beams. Opt Express 2022; 30:11360-11371. [PMID: 35473082 DOI: 10.1364/oe.454796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 03/05/2022] [Indexed: 06/14/2023]
Abstract
Bessel beams generated with non-ideal axicons are affected by aberrations. We introduce a method to retrieve the complex amplitude of a Bessel beam from intensity measurements alone, and then use this information to correct the wavefront and intensity profile using a deformable mirror.
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Chou E, Ganti A, Katranji K, Cotarla I, Sharma C, Miao B, Garg M, Seal B. OFP01.09 Economic Burden of Metastatic Non-Small Cell Lung Cancer (mNSCLC) in a Large United States (US) Claims Database. J Thorac Oncol 2021. [DOI: 10.1016/j.jtho.2020.10.041] [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: 11/26/2022]
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Miao B, Feder L, Shrock JE, Goffin A, Milchberg HM. Optical Guiding in Meter-Scale Plasma Waveguides. Phys Rev Lett 2020; 125:074801. [PMID: 32857573 DOI: 10.1103/physrevlett.125.074801] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/05/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate a new highly tunable technique for generating meter-scale low density plasma waveguides. Such guides can enable laser-driven electron acceleration to tens of GeV in a single stage. Plasma waveguides are imprinted in hydrogen gas by optical field ionization induced by two time-separated Bessel beam pulses: The first pulse, a J_{0} beam, generates the core of the waveguide, while the delayed second pulse, here a J_{8} or J_{16} beam, generates the waveguide cladding, enabling wide control of the guide's density, depth, and mode confinement. We demonstrate guiding of intense laser pulses over hundreds of Rayleigh lengths with on-axis plasma densities as low as N_{e0}∼5×10^{16} cm^{-3}.
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Affiliation(s)
- B Miao
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| | - L Feder
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| | - J E Shrock
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| | - A Goffin
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| | - H M Milchberg
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
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Salehi F, Goers AJ, Hine GA, Feder L, Kuk D, Miao B, Woodbury D, Kim KY, Milchberg HM. MeV electron acceleration at 1 kHz with <10 mJ laser pulses: erratum. Opt Lett 2018; 43:1610. [PMID: 29601042 DOI: 10.1364/ol.43.001610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Indexed: 06/08/2023]
Abstract
In this erratum the funding section of Opt. Lett.42, 215 (2017)OPLEDP0146-959210.1364/OL.42.000215 has been updated.
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Woodbury D, Feder L, Shumakova V, Gollner C, Schwartz R, Miao B, Salehi F, Korolov A, Pugžlys A, Baltuška A, Milchberg HM. Laser wakefield acceleration with mid-IR laser pulses. Opt Lett 2018; 43:1131-1134. [PMID: 29489797 DOI: 10.1364/ol.43.001131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 01/30/2018] [Indexed: 06/08/2023]
Abstract
We report on, to the best of our knowledge, the first results of laser plasma wakefield acceleration driven by ultrashort mid-infrared (IR) laser pulses (λ=3.9 μm, 100 fs, 0.25 TW), which enable near- and above-critical density interactions with moderate-density gas jets. Relativistic electron acceleration up to ∼12 MeV occurs when the jet width exceeds the threshold scale length for relativistic self-focusing. We present scaling trends in the accelerated beam profiles, charge, and spectra, which are supported by particle-in-cell simulations and time-resolved images of the interaction. For similarly scaled conditions, we observe significant increases in the accelerated charge, compared to previous experiments with near-infrared (λ=800 nm) pulses.
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Salehi F, Goers AJ, Hine GA, Feder L, Kuk D, Miao B, Woodbury D, Kim KY, Milchberg HM. MeV electron acceleration at 1 kHz with <10 mJ laser pulses. Opt Lett 2017; 42:215-218. [PMID: 28081077 DOI: 10.1364/ol.42.000215] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/30/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate laser-driven acceleration of electrons to MeV-scale energies at 1 kHz repetition rate using <10 mJ pulses focused on near-critical density He and H2 gas jets. Using the H2 gas jet, electron acceleration to ∼0.5 MeV in ∼10 fC bunches was observed with laser pulse energy as low as 1.3 mJ. Increasing the pulse energy to 10 mJ, we measure ∼1 pC charge bunches with >1 MeV energy for both He and H2 gas jets.
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Brunetti L, Chapy H, Miao B, Kagan L. P232 Endogenous serum immunoglobulin levels in hospitalized patients. Ann Allergy Asthma Immunol 2016. [DOI: 10.1016/j.anai.2016.09.244] [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: 10/20/2022]
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Zhao DD, Huang ZY, Hong LQ, Liao T, Tang YE, Na N, Li H, Miao B, Hua XF, Sun QQ. [Massive hemorrhage caused by fungal infections after donation-after-cardiac-death kidney transplantation: clinical features, prevention and treatment experience]. Zhonghua Yi Xue Za Zhi 2016; 96:1570-2. [PMID: 27266684 DOI: 10.3760/cma.j.issn.0376-2491.2016.20.005] [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] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE To study the characteristics and prevention and treatment strategies of massive hemorrhage caused by fungal infections after donation-after-cardiac-death (DCD) kidney transplantation. METHODS A total of 91 cases of DCD kidney transplantation between August 25, 2013 and June 30, 2015 in Third Affiliated Hospital of Sun Yat-sen Univservity were retrospectively analyzed. The characteristics of and prevention and treatments strategies for postoperative massive hemorrhage caused by fungal infections were summarized. RESULTS Ninety-one cases of DCD kidney transplantation were divided into 2 groups based on regimens for preventing postoperative fungal infections: fluconazole prophylaxis group: a total of 26 cases of renal transplant before June 11, 2014 received fluconazole regimen, from postoperative day 0 to 2 weeks; micafungin prophylaxis group: a total of 65 cases of renal transplant after June 11, 2014 received micafungin regimen, also for 2 weeks from postoperative day 0. Two cases in fluconazole group developed postoperative massive hemorrhage. In case 1, the hemorrhage occurred at 2 weeks after transplantation. Graft nephrectomy was performed during surgical exploration for hemostasis, yet the massive hemorrhage relapsed 2 weeks later. Endoluminal exclusion of external iliac artery using endovascular covered stent-graft at the anastomosis site was performed and the massive bleeding was successfully stopped. The patient was restored to hemodialysis and waited for second kidney transplantation. Candia albicans was detected in the culture of blood and drainage liquid from incision. The other case of hemorrhage occurred at 3 weeks after transplantation. Graft nephrectomy plus endovascular exclusion using covered stent-graft were also performed to stop the massive bleeding. Massive fungal hyphae and spores were observed at the stump of renal graft artery under microscope. The patient received second kidney transplantation after 6 months successfully. No massive hemorrhage caused by fungal infections occurred in micafungin prophylaxis group. CONCLUSIONS Massive hemorrhage cased by fungal infections after DCD kidney transplantation is usually characterized by delayed and recurrent course, and may result in graft nephrectomy or even death of patients. Endovascular exclusion using covered stent can successfully stop bleeding and rescue life of patients. Two-week preemptive prophylaxis of fungal infections using micafungin can effectively prevent delayed fungal massive hemorrhage in DCD kidney transplantation.
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Affiliation(s)
- D D Zhao
- Department of Kidney Transplantation, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510760, China
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Goers AJ, Hine GA, Feder L, Miao B, Salehi F, Wahlstrand JK, Milchberg HM. Multi-MeV Electron Acceleration by Subterawatt Laser Pulses. Phys Rev Lett 2015; 115:194802. [PMID: 26588390 DOI: 10.1103/physrevlett.115.194802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 06/05/2023]
Abstract
We demonstrate laser-plasma acceleration of high charge electron beams to the ∼10 MeV scale using ultrashort laser pulses with as little energy as 10 mJ. This result is made possible by an extremely dense and thin hydrogen gas jet. Total charge up to ∼0.5 nC is measured for energies >1 MeV. Acceleration is correlated to the presence of a relativistically self-focused laser filament accompanied by an intense coherent broadband light flash, associated with wave breaking, which can radiate more than ∼3% of the laser energy in a ∼1 fs bandwidth consistent with half-cycle optical emission. Our results enable truly portable applications of laser-driven acceleration, such as low dose radiography, ultrafast probing of matter, and isotope production.
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Affiliation(s)
- A J Goers
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - G A Hine
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - L Feder
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - B Miao
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - F Salehi
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - J K Wahlstrand
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - H M Milchberg
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
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Dong C, Miao B, Tan C, Wei D, Wu Y. An Estimate of a Change Point in Variance of Measurement Errors and Its Convergence Rate. COMMUN STAT-THEOR M 2015. [DOI: 10.1080/03610926.2012.762395] [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: 10/27/2022]
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Zhao D, Wang L, Na N, Huang Z, Miao B, Hong L. A model of isolated, vascular whole thymus transplantation in nude rats. Transplant Proc 2012; 44:1394-8. [PMID: 22664022 DOI: 10.1016/j.transproceed.2011.10.055] [Citation(s) in RCA: 5] [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: 09/23/2011] [Accepted: 10/27/2011] [Indexed: 11/29/2022]
Abstract
BACKGROUND We used a model of vascularized thymus lobes as a whole isolated organ transplantation in rats. MATERIALS AND METHODS Male Fisher rats (F344, RT11v1; n = 10) and male homozygous Rowett nude rats (rnu/rnu; n = 10) were used as donors and recipients, respectively. Both vascular lobes of the thymus as a whole isolated organ were heterotopically transplanted to the neck of recipients. The right common carotid artery of the donor thymus was anastomosed end-to-end to the homonymous artery of the recipient. The anterior vena cava and the left brachiocephalic vein of the donor thymus were anastomosed end-to-side to the right and left external jugular veins of the recipient, respectively. Histological examination was used to monitor graft viability; graft function was assessed using flow cytometry (FCM) and immunologic effects by skin grafts in vivo. RESULTS All recipients survived. Preparation of the donors and recipients took 35.6 ± 5.5 minutes and 60.3 ± 15.1 minutes, respectively. The blood supply to the thymus graft was patent. Histology of the thymus on postoperative days 14, 56, and 112 revealed viable grafts with preserved microarchitecture. FCM analysis showed 37.18 ± 11.1% CD3+ T cells at day 21 after transplantation. Skin grafts from F344 and Rowett rats survived 8-10 and more than 30 days, respectively, whereas all third-party Sprague Dawley grafts were rejected within 5 days. CONCLUSION We developed a novel model of isolated, direct vascularized whole thymus transplantation in nude rats, in which both lobes of the fully vascularized thymus were harvested en bloc for successful transplantation.
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Affiliation(s)
- D Zhao
- Department of Kidney Transplantation, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
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Li G, Miao B, Hu Q, Qin G. Effect of current sheets on the solar wind magnetic field power spectrum from the Ulysses observation: from Kraichnan to Kolmogorov scaling. Phys Rev Lett 2011; 106:125001. [PMID: 21517318 DOI: 10.1103/physrevlett.106.125001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Indexed: 05/30/2023]
Abstract
The MHD turbulence theory developed by Iroshnikov and Kraichnan predicts a k(-1.5) power spectrum. Solar wind observations, however, often show a k(-5/3) Kolmogorov scaling. Based on 3 years worth of Ulysses magnetic field data where over 28,000 current sheets are identified, we propose that the current sheet is the cause of the Kolmogorov scaling. We show that for 5 longest current-sheet-free periods the magnetic field power spectra are all described by the Iroshnikov-Kraichnan scaling. In comparison, for 5 periods that have the most number of current sheets, the power spectra all exhibit Kolmogorov scaling. The implication of our results is discussed.
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Affiliation(s)
- G Li
- Department of Physics and CSPAR, University of Alabama in Huntsville, Alabama 35899, USA.
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Chen Y, Zhang K, Miao B, Wang B, Hou J. Temperature dependence of morphology and diameter of silicon nanowires synthesized by laser ablation. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(02)00671-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Guan H, Gong Q, Miao B. [Inquiries about methods of primary eye care and prevention of blindness]. Zhonghua Yan Ke Za Zhi 2001; 37:9-11. [PMID: 11864379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To inquire about the methods of developing primary eye care (PEC) and prevention of blindness. METHODS The methods of developing PEC and prevention of blindness in recent 10 years were analyzed retrospectively. RESULTS Five grades of PEC network were established. The training courses 1 007 times were held in Nantong, and the epidemiological survey of the blind was carried out for 6 817 259 people. The blind persons were 13 496 in number, and the prevalence of blindness was 0.20%. Cataract operations were performed on 83.16% of the treatable cataract blind persons. The successful rate of cataract surgery was 98.22%. Eight counties became the national advanced counties of prevention of blindness. Nantong city became the first national advanced city of prevention of blindness in 1997. CONCLUSIONS PEC is the basis of prevention of blindness. To bring PEC into line with the primary health care (PHC) is the key point of developing PEC. Affordable operation, promising quality of the operative procedure and combination of survey and treatment are the three essential factors of developing PEC and prevention of blindness. To create national advanced county and city is the motive force of developing prevention of blindness.
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Affiliation(s)
- H Guan
- Department of Ophthalmology, Affiliated Hospital, Nantong Medical College, Nantong 226001, China
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Abstract
Re-investigation of the aerial parts of Iva frutescens resulted in the isolation of three sesquiterpenes, two of which are new natural products, and their structures were established by spectral data.
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Affiliation(s)
- A A Ahmed
- Department of Chemistry, Faculty of Science, El-Minia University, Egypt
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Abstract
Mge1, a GrpE-related protein in the mitochondrial matrix of the budding yeast Saccharomyces cerevisiae, is required for translocation of precursor proteins into mitochondria. The effect of Mge1 on nucleotide release from Ssc1, an Hsp70 of the mitochondrial matrix, was analyzed. The release of both ATP and ADP from Ssc1 was stimulated in the presence of Mge1, therefore we conclude that Mge1 functions as a nucleotide release factor for Ssc1. Mge1 bound stably to Ssc1 in vitro; this interaction was resistant to high concentrations of salt but was disrupted by the addition of ATP. ADP was much less effective in releasing Mge1 from Ssc1 whereas ATP gamma S and AMPPNP could not disrupt the Ssc1/Mge1 complex. Ssc1-3, a temperature sensitive SSC1 mutant protein, did not form a detectable complex with Mge1. Consistent with the lack of a detectable interaction, Mge1 did not stimulate nucleotide release from Ssc1-3. A conserved loop structure on the surface of the ATPase domain of DnaK has been implicated in its interaction with GrpE. Since the single amino acid change in Ssc1-3 lies very close to the analogous loop in Ssc1, the role of this loop in the Ssc1:Mge1 interaction was investigated. Deletion of the loop abolished the physical and functional interaction of Ssc1 with Mge1, suggesting that the loop in Ssc1 is also important for the Ssc1:Mge1 interaction. Two mutants with single amino acid changes within the loop did not eliminate the stable binding of Mge1, yet the binding of Mge1 did not stimulate the release of nucleotides from the mutant SSC1 proteins. We propose that the loop region of Ssc1 is important for the physical interaction between Mge1 and Ssc1, and for generation of a conformational change necessary for Mge1-induced nucleotide release.
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Affiliation(s)
- B Miao
- Department of Biomolecular Chemistry, University of Wisconsin, Madison 53706, USA
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Schilke B, Forster J, Davis J, James P, Walter W, Laloraya S, Johnson J, Miao B, Craig E. The cold sensitivity of a mutant of Saccharomyces cerevisiae lacking a mitochondrial heat shock protein 70 is suppressed by loss of mitochondrial DNA. J Biophys Biochem Cytol 1996; 134:603-13. [PMID: 8707841 PMCID: PMC2120932 DOI: 10.1083/jcb.134.3.603] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
SSH1, a newly identified member of the heat shock protein (hsp70) multigene family of the budding yeast Saccharomyces cerevisiae, encodes a protein localized to the mitochondrial matrix. Deletion of the SSH1 gene results in extremely slow growth at 23 degrees C or 30 degrees C, but nearly wild-type growth at 37 degrees C. The matrix of the mitochondria contains another hsp70, Ssc1, which is essential for growth and required for translocation of proteins into mitochondria. Unlike SSC1 mutants, an SSH1 mutant showed no detectable defects in import of several proteins from the cytosol to the matrix compared to wild type. Increased expression of Ssc1 partially suppressed the cold-sensitive growth defect of the SSH1 mutant, suggesting that when present in increased amounts, Ssc1 can at least partially carry out the normal functions of Ssh1. Spontaneous suppressors of the cold-sensitive phenotype of an SSH1 null mutant were obtained at a high frequency at 23 degrees C, and were all found to be respiration deficient. 15 of 16 suppressors that were analyzed lacked mitochondrial DNA, while the 16th had reduced amounts. We suggest that Ssh1 is required for normal mitochondrial DNA replication, and that disruption of this process in ssh1 cells results in a defect in mitochondrial function at low temperatures.
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Affiliation(s)
- B Schilke
- Department of Biomolecular Chemistry, University of Wisconsin, Madison 53706, USA
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Gambill BD, Voos W, Kang PJ, Miao B, Langer T, Craig EA, Pfanner N. A dual role for mitochondrial heat shock protein 70 in membrane translocation of preproteins. J Biophys Biochem Cytol 1993; 123:109-17. [PMID: 8408191 PMCID: PMC2119813 DOI: 10.1083/jcb.123.1.109] [Citation(s) in RCA: 226] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The role of mitochondrial 70-kD heat shock protein (mt-hsp70) in protein translocation across both the outer and inner mitochondrial membranes was studied using two temperature-sensitive yeast mutants. The degree of polypeptide translocation into the matrix of mutant mitochondria was analyzed using a matrix-targeted preprotein that was cleaved twice by the processing peptidase. A short amino-terminal segment of the preprotein (40-60 amino acids) was driven into the matrix by the membrane potential, independent of hsp70 function, allowing a single cleavage of the presequence. Artificial unfolding of the preprotein allowed complete translocation into the matrix in the case where mutant mt-hsp70 had detectable binding activity. However, in the mutant mitochondria in which binding to mt-hsp70 could not be detected the mature part of the preprotein was only translocated to the intermembrane space. We propose that mt-hsp70 fulfills a dual role in membrane translocation of preproteins. (a) Mt-hsp70 facilitates unfolding of the polypeptide chain for translocation across the mitochondrial membranes. (b) Binding of mt-hsp70 to the polypeptide chain is essential for driving the completion of transport of a matrix-targeted preprotein across the inner membrane. This second role is independent of the folding state of the preprotein, thus identifying mt-hsp70 as a genuine component of the inner membrane translocation machinery. Furthermore we determined the sites of the mutations and show that both a functional ATPase domain and ATP are needed for mt-hsp70 to bind to the polypeptide chain and drive its translocation into the matrix.
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Affiliation(s)
- B D Gambill
- Department of Biomolecular Chemistry, University of Wisconsin-Madison 53706
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