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Reuthner K, Aubele P, Menhart K, Rath P, Harrer DC, Herr W, Hahn J, Vogelhuber M, Heudobler D, Lueke F, Reichle A, Grube M. Case report: Sustained complete remission with all-oral MEPED therapy in a patient with Hodgkin's disease developing resistance to pembrolizumab. Front Pharmacol 2024; 15:1334233. [PMID: 38444946 PMCID: PMC10912635 DOI: 10.3389/fphar.2024.1334233] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 01/26/2024] [Indexed: 03/07/2024] Open
Abstract
Targeted chemotherapy and immune checkpoint inhibitors (ICPi) have expanded the spectrum of therapies for patients with relapsed/refractory (r/r) Hodgkin's disease and significantly improved the proportion of patients with long-term disease control. However, there is no standardized therapeutic option in case of further progression. Recently, we demonstrated that therapy with MEPED (metronomic chemotherapy, everolimus, pioglitazone, etoricoxib, dexamethasone) is highly effective in patients with r/r Hodgkin's disease. The benefit after pre-treatment with ICPi has not been studied, yet. Here, we report a patient with progressive Hodgkin's disease on Pembrolizumab for the first time who achieved sustained complete remission (CR) after initiation of MEPED therapy. A 57-year-old patient was pre-treated with brentuximab vedotin for relapsed advanced Hodgkin's disease and had received Pembrolizumab for progression from November 2020 to July 2022. Due to further progression, MEPED therapy was started in August 2022 and continued until May 2023. It consisted of a strictly oral daily (28-day cycle) application of low-dose treosulfan 250 mg, everolimus 15 mg, pioglitazone 45 mg, etoricoxib 60 mg, and dexamethasone 0.5 mg. Treatment response was evaluated by F-18 FDG-PET/CT (PET/CT). CR was defined by a negative Deauville score (DS) of 1-3. Already 3 months after starting MEPED, a CR (DS: 3) was confirmed by PET/CT in November 2022. The next follow-up in May 2023 continued to show CR (DS: 3). The therapy was very well tolerated. No hematological or other organ toxicity was observed. However, in May 2023 the patient presented with leg edema and weight gain, most likely due to pioglitazone and the PET/CT revealed suspected everolimus-induced pneumonitis, so MEPED was discontinued and diuretic therapy and treatment with prednisolone was started with gradual dose reduction. This resulted in a rapid complete resolution of the symptoms. The next PET-CT in July 2023 continued to show CR (DS: 3) without evidence of pneumonitis. Currently, therapy with MEPED has not been resumed. In conclusion, we demonstrate for the first time that MEPED therapy is highly effective in a patient with Hodgkin's disease who has been refractory to ICPi. Sustained CR was achieved over 11 months after initiation of MEPED therapy. Further studies on a larger patient cohort should be performed.
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Affiliation(s)
- K. Reuthner
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
| | - P. Aubele
- Medical Care Center (MVZ), Oncology, Hospital of Straubing, Straubing, Germany
| | - K. Menhart
- Department of Nuclear Medicine, University Hospital of Regensburg, Regensburg, Germany
| | - P. Rath
- Department of Nuclear Medicine, University Hospital of Regensburg, Regensburg, Germany
| | - D. C. Harrer
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
| | - W. Herr
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
| | - J. Hahn
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
| | - M. Vogelhuber
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
| | - D. Heudobler
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
- Bavarian Cancer Research Center (BZKF), University Hospital Regensburg, Regensburg, Germany
| | - F. Lueke
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
- Division of Personalized Tumor Therapy, Fraunhofer Institute for Toxicology and Experimental Medicine, Regensburg, Germany
| | - A. Reichle
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
| | - M. Grube
- Department of Internal Medicine III, Hematology and Oncology, University Hospital of Regensburg, Regensburg, Germany
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Cahyanto A, Rath P, Teo TX, Tong SS, Malhotra R, Cavalcanti BN, Lim LZ, Min KS, Ho D, Lu WF, Rosa V. Designing Calcium Silicate Cements with On-Demand Properties for Precision Endodontics. J Dent Res 2023; 102:1425-1433. [PMID: 37861249 DOI: 10.1177/00220345231198185] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023] Open
Abstract
Calcium silicate (C3S) cements are available in kits that do not account for patients' specific needs or clinicians' preferences regarding setting time, radiopacity, mechanical, and handling properties. Moreover, slight variations in powder components and liquid content affect cement's properties and bioactivity. Unfortunately, it is virtually impossible to optimize several cement properties simultaneously via the traditional "one variable at a time" strategy, as inputs often induce trade-offs in properties (e.g., a higher water-to-powder ratio [W/P] increases flowability but decreases mechanical properties). Herein, we used Taguchi's methods and genetic algorithms (GAs) to simultaneously analyze the effect of multiple inputs (e.g., powder composition, radiopacifier concentration, and W/P) on setting time, pH, flowability, diametral tensile strength, and radiopacity, as well as prescribe recipes to produce cements with predicted properties. The properties of cements designed with GAs were experimentally tested, and the results matched the predictions. Finally, we show that the cements increased the genetic expression of odonto/osteogenic genes, alkaline phosphatase activity, and mineralization potential of dental pulp stem cells. Hence, GAs can produce cements with tailor-made properties and differentiation potential for personalized endodontic treatment.
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Affiliation(s)
- A Cahyanto
- Department of Restorative Dentistry, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
- Department of Dental Materials Science and Technology, Faculty of Dentistry, Padjadjaran University, Bandung, Indonesia
| | - P Rath
- Faculty of Dentistry, National University of Singapore, Singapore
| | - T X Teo
- Department of Mechanical Engineering, College of Design and Engineering, National University of Singapore, Singapore
| | - S S Tong
- Department of Mechanical Engineering, College of Design and Engineering, National University of Singapore, Singapore
| | - R Malhotra
- Faculty of Dentistry, National University of Singapore, Singapore
| | - B N Cavalcanti
- Department of Cariology, Restorative Sciences and Endodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - L Z Lim
- Faculty of Dentistry, National University of Singapore, Singapore
| | - K S Min
- Department of Conservative Dentistry, School of Dentistry, Jeonbuk National University, Jeonju, Republic of Korea
| | - D Ho
- Department of Biomedical Engineering, College of Design and Engineering, National University of Singapore, Singapore
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- ORCHIDS: Oral Care Health Innovations and Designs Singapore, National University of Singapore, Singapore
| | - W F Lu
- Department of Mechanical Engineering, College of Design and Engineering, National University of Singapore, Singapore
| | - V Rosa
- Faculty of Dentistry, National University of Singapore, Singapore
- ORCHIDS: Oral Care Health Innovations and Designs Singapore, National University of Singapore, Singapore
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Rath P, Rapp J, Brilisauer K, Braun M, Kolukisaoglu Ü, Forchhammer K, Grond S. Hybrid Chemoenzymatic Synthesis of C7-Sugars for Molecular Evidence of in vivo Shikimate Pathway Inhibition. Chembiochem 2022; 23:e202200241. [PMID: 35508894 PMCID: PMC9401589 DOI: 10.1002/cbic.202200241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Indexed: 11/22/2022]
Abstract
The design of distinctive chemical synthesis strategies aims for the most efficient routes towards versatile compounds in drug target studies. Here, we establish a powerful hybrid synthetic approach of total chemical and chemoenzymatic synthesis to efficiently obtain various 7‐deoxy‐sedoheptulose (7dSh, 1) analogues, unique C7 sugars, for structure‐activity relationship studies. 7dSh (1) is a rare microbial sugar with in planta herbicidal activity. As natural antimetabolite of 3‐dehydroquinate synthase (DHQS), 7dSh (1) inhibits the shikimate pathway, which is essential for the synthesis of aromatic amino acids in bacteria, fungi, and plants, but absent in mammals. As glyphosate, the most used chemical herbicide faces restrictions worldwide, DHQS has gained more attention as valid target of herbicides and antimicrobial agents. In vitro and in vivo analyses of the C7‐deoxysugars confirm DHQS as enzymatic target, highlight the crucial role of uptake for inhibition and add molecular aspects to target mechanism studies of C7‐sugars as our contribution to global efforts for alternative weed‐control strategies.
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Affiliation(s)
- Pascal Rath
- Eberhard Karls Universitat Tubingen, Institute of Organic Chemistry, Biomolecluar Chemistry, Auf der Morgenstelle 18, 72076, Tuebingen, GERMANY
| | - Johanna Rapp
- Eberhard Karls Universitat Tubingen, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Auf der Morgenstelle 28, 72076, Tuebingen, GERMANY
| | - Klaus Brilisauer
- Eberhard Karls Universitat Tubingen, Institute of Organic Chemistry, Biomolecular Chemistry, Auf der Morgenstelle 18, 72076, Tuebingen, GERMANY
| | - Marvin Braun
- Eberhard Karls Universitat Tubingen, Center for Plant Molecular Biology (ZMBP), Auf der Morgenstelle 32, 72076, Tuebingen, GERMANY
| | - Üner Kolukisaoglu
- Eberhard Karls Universitat Tubingen, Center for Plant Molecular Biology (ZMBP), Auf der Morgenstelle 32, 72076, Tuebingen, GERMANY
| | - Karl Forchhammer
- Eberhard Karls Universitat Tubingen, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Auf der Morgenstelle 28, 72076, Tuebingen, GERMANY
| | - Stephanie Grond
- Eberhard Karls Universität Tübingen Mathematisch-Naturwissenschaftliche Fakultät: Eberhard Karls Universitat Tubingen Mathematisch-Naturwissenschaftliche Fakultat, Institute of Organic Chemistry, Auf der Morgenstelle 18, 72076, Tübingen, GERMANY
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Barman C, Rath P, Bhattacharya A. A Non-Fourier Bioheat Transfer Model for Cryosurgery of Tumor Tissue with Minimum Collateral Damage. Comput Methods Programs Biomed 2021; 200:105857. [PMID: 33280936 DOI: 10.1016/j.cmpb.2020.105857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/15/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND OBJECTIVES Incorporation of non-Fourier heat conduction while studying heat transfer phenomena in biological materials has emerged has an important approach as it predicts better and more realistic results than Fourier based models. In this article we have proposed a non-Fourier computational model and applied the same to simulate cryosurgery of lung tumor and attempted minimization of freezing damage of healthy lung tissue using pulsed laser irradiation. METHODS A non-Fourier bioheat transfer model for phase change in biological tissues is solved via a Fourier heat conduction based solution approach. A unified model is proposed combining all variants of bioheat models: Fourier's heat conduction based Pennes' bioheat model, hyperbolic heat conduction model and dual phase lag model. The proposed model takes into account the different thermophysical properties of frozen and unfrozen regions. In order to mimic the actual biotransport process, the blood perfusion and metabolic heat generation are switched off in the frozen region. Implicit source based enthalpy method is used to model phase change process. A new iterative enthalpy update equation is developed for capturing evolution of freezing front implicitly. Finite Volume based numerical discretization technique is used to discretize the governing PDE. The resulting discrete algebraic equation set is solved implicitly by Tri-diagonal Matrix Algorithm. The proposed model is verified with existing results from the literature. RESULTS For Fourier heat conduction, freezing time of 99.99% of tumor is 1247s, which increases to 1267s for τq= 5s (τT= 0s) and again reduces to 1255s for τq= 5s and τT= 3s. τq and τT are phase lag parameters for non-Fourier heat conduction. For τq= 5s and τT= 0.05s, the freezing damage of healthy tissue decreases by 23.76% when pulsed laser irradiation (Io = 106 W/m2) is used to warm the neighboring healthy tissue. CONCLUSIONS So non-Fourier bioheat transport models are better and more accurate in predicting temperature history, freezing time and freezing front propagation as compared to Fourier based models. Pulsed laser irradiation can prove to be a very efficient technique in minimizing collateral damage during cryosurgery.
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Affiliation(s)
- C Barman
- Heat Transfer Laboratory, School of Mechanical Sciences, Indian Institute of Technology, Bhubaneswar, Odisha, India, 752050
| | - P Rath
- Heat Transfer Laboratory, School of Mechanical Sciences, Indian Institute of Technology, Bhubaneswar, Odisha, India, 752050.
| | - A Bhattacharya
- Heat Transfer Laboratory, School of Mechanical Sciences, Indian Institute of Technology, Bhubaneswar, Odisha, India, 752050
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Rapp J, Rath P, Kilian J, Brilisauer K, Grond S, Forchhammer K. A bioactive molecule made by unusual salvage of radical SAM enzyme byproduct 5-deoxyadenosine blurs the boundary of primary and secondary metabolism. J Biol Chem 2021; 296:100621. [PMID: 33811856 PMCID: PMC8102628 DOI: 10.1016/j.jbc.2021.100621] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/25/2021] [Accepted: 03/30/2021] [Indexed: 12/26/2022] Open
Abstract
5-Deoxyadenosine (5dAdo) is the byproduct of many radical S-adenosyl-l-methionine enzyme reactions in all domains of life. 5dAdo is also an inhibitor of the radical S-adenosyl-l-methionine enzymes themselves, making it necessary for cells to construct pathways to recycle or dispose of this toxic metabolite. However, the specific pathways involved have long remained unexplored. Recent research demonstrated a growth advantage in certain organisms by using 5dAdo or intermediates as a sole carbon source and elucidated the corresponding salvage pathway. We now provide evidence using supernatant analysis by GC-MS for another 5dAdo recycling route. Specifically, in the unicellular cyanobacterium Synechococcus elongatus PCC 7942 (S. elongatus), the activity of promiscuous enzymes leads to the synthesis and excretion first of 5-deoxyribose and subsequently of 7-deoxysedoheptulose. 7-Deoxysedoheptulose is an unusual deoxy-sugar, which acts as an antimetabolite of the shikimate pathway, thereby exhibiting antimicrobial and herbicidal activity. This strategy enables organisms with small genomes and lacking canonical gene clusters for the synthesis of secondary metabolites, like S. elongatus, to produce antimicrobial compounds from primary metabolism and enzymatic promiscuity. Our findings challenge the view of bioactive molecules as sole products of secondary metabolite gene clusters and expand the range of compounds that microorganisms can deploy to compete for their ecological niche.
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Affiliation(s)
- Johanna Rapp
- Interfaculty Institute of Microbiology and Infection Medicine, Microbiology/Organismic Interactions, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Pascal Rath
- Institute of Organic Chemistry, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Joachim Kilian
- Center for Plant Molecular Biology, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Klaus Brilisauer
- Interfaculty Institute of Microbiology and Infection Medicine, Microbiology/Organismic Interactions, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Stephanie Grond
- Institute of Organic Chemistry, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Karl Forchhammer
- Interfaculty Institute of Microbiology and Infection Medicine, Microbiology/Organismic Interactions, Eberhard Karls Universität Tübingen, Tübingen, Germany.
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Sethy N, Sutar A, Rath P, Jha V, Ravi P, Tripathi R. A review of radio chemical analysis and estimation of 210Po in soil matrices. Journal of Radiation Research and Applied Sciences 2019. [DOI: 10.1016/j.jrras.2015.07.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- N.K. Sethy
- Health Physics Division, Bhabha Atomic Research Centre, Health Physics Unit, Jaduguda, Jharkhand, 832102, India
| | - A.K. Sutar
- Deparment of Chemistry, Ravenshaw University, Cuttack, Odisha, India
| | - P. Rath
- School of Applied Sciences, KIIT University, Bhubaneswar, Odisha, India
| | - V.N. Jha
- Health Physics Division, Bhabha Atomic Research Centre, Health Physics Unit, Jaduguda, Jharkhand, 832102, India
| | - P.M. Ravi
- Health physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India
| | - R.M. Tripathi
- Health physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India
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7
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Brilisauer K, Rapp J, Rath P, Schöllhorn A, Bleul L, Weiß E, Stahl M, Grond S, Forchhammer K. Cyanobacterial antimetabolite 7-deoxy-sedoheptulose blocks the shikimate pathway to inhibit the growth of prototrophic organisms. Nat Commun 2019; 10:545. [PMID: 30710081 PMCID: PMC6358636 DOI: 10.1038/s41467-019-08476-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [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: 07/10/2018] [Accepted: 01/09/2019] [Indexed: 11/17/2022] Open
Abstract
Antimetabolites are small molecules that inhibit enzymes by mimicking physiological substrates. We report the discovery and structural elucidation of the antimetabolite 7-deoxy-sedoheptulose (7dSh). This unusual sugar inhibits the growth of various prototrophic organisms, including species of cyanobacteria, Saccharomyces, and Arabidopsis. We isolate bioactive 7dSh from culture supernatants of the cyanobacterium Synechococcus elongatus. A chemoenzymatic synthesis of 7dSh using S. elongatus transketolase as catalyst and 5-deoxy-d-ribose as substrate allows antimicrobial and herbicidal bioprofiling. Organisms treated with 7dSh accumulate 3-deoxy-d-arabino-heptulosonate 7-phosphate, which indicates that the molecular target is 3-dehydroquinate synthase, a key enzyme of the shikimate pathway, which is absent in humans and animals. The herbicidal activity of 7dSh is in the low micromolar range. No cytotoxic effects on mammalian cells have been observed. We propose that the in vivo inhibition of the shikimate pathway makes 7dSh a natural antimicrobial and herbicidal agent. Mother Nature is a valuable resource for the discovery of drug and agricultural chemicals. Here, the authors show that 7-deoxy-sedoheptulose produced by a cyanobacterium is an antimicrobial and herbicidal compound that acts through inhibition of 3-dehydroquniate synthase in the shikimate pathway.
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Affiliation(s)
- Klaus Brilisauer
- Institute of Organic Chemistry, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany.,Microbiology, Organismic Interactions, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Johanna Rapp
- Microbiology, Organismic Interactions, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Pascal Rath
- Institute of Organic Chemistry, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
| | - Anna Schöllhorn
- Microbiology, Organismic Interactions, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Lisa Bleul
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Eberhard Karls Universität Tübingen, Eugenstraße 6, 72076, Tübingen, Germany
| | - Elisabeth Weiß
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Eberhard Karls Universität Tübingen, Eugenstraße 6, 72076, Tübingen, Germany
| | - Mark Stahl
- Center for Plant Molecular Biology, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Stephanie Grond
- Institute of Organic Chemistry, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany.
| | - Karl Forchhammer
- Microbiology, Organismic Interactions, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany.
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Stokes PA, Rath P, Manoach DS, Stickgold R, Prerau MJ. 0999 Characterizing Clinical Population Differences in Transient Oscillation Features in the Sleep EEG. Sleep 2018. [DOI: 10.1093/sleep/zsy061.998] [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] [Indexed: 11/14/2022] Open
Affiliation(s)
- P A Stokes
- Massachusetts General Hospital, Charlestown, MA
| | - P Rath
- Massachusetts General Hospital, Charlestown, MA
| | - D S Manoach
- Massachusetts General Hospital, Charlestown, MA
| | - R Stickgold
- Beth Israel Deaconess Medical Center, Boston, MA
| | - M J Prerau
- Massachusetts General Hospital, Charlestown, MA
- Massachusetts General Hospital, Charlestown, MA
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Costa R, Seth A, Chandra P, Bhal V, Nanjappa M, Rath P, Kalaricka M, Wander G, Mahajan A, Kumaran A, Koshy A, Goel P, Kumar V, Kaul U, Trehan V. 1968Quantitative angiographic analysis in patients with de novo native coronary artery lesions treated with novel poly-l-lactide based sirolimus-eluting bioresorbable vascular scaffold: MeRes-1 Trial. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx502.1968] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Suneeta K, Rath P, Sri HKA. Chitosan from shrimp shell (Crangon crangon) and fish scales (Labeorohita): Extraction and characterization. ACTA ACUST UNITED AC 2016. [DOI: 10.5897/ajb2015.15138] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Ravindran V, Jain R, Thabah M, Nalawade A, Kumar P, Agrawal S, Rath P, Upadhyaya S, Kaushik V, Kiran R, Sekhri R, Sekhri V, Shukla J, Pandey K, Malviya S, Ghosh P, Pandey B. FRI0449 Incidence and Prevalence of Psoriatic Arthritis in South East Asia. Ann Rheum Dis 2016. [DOI: 10.1136/annrheumdis-2016-eular.4702] [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: 11/03/2022]
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Pani GK, Rath P, Barik R, Senapati PK. The Effect of Selective Additives on the Rheological Behavior of Power Plant Ash Slurry. Particulate Science and Technology 2015. [DOI: 10.1080/02726351.2014.990657] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Rath P, Gruhler N, Khasminskaya S, Nebel C, Wild C, Pernice WHP. Waferscale nanophotonic circuits made from diamond-on-insulator substrates. Opt Express 2013; 21:11031-11036. [PMID: 23669959 DOI: 10.1364/oe.21.011031] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Wide bandgap dielectrics are attractive materials for the fabrication of photonic devices because they allow broadband optical operation and do not suffer from free-carrier absorption. Here we show that polycrystalline diamond thin films deposited by chemical vapor deposition provide a promising platform for the realization of large scale integrated photonic circuits. We present a full suite of photonic components required for the investigation of on-chip devices, including input grating couplers, millimeter long nanophotonic waveguides and microcavities. In microring resonators we measure loaded optical quality factors up to 11,000. Corresponding propagation loss of 5 dB/mm is also confirmed by measuring transmission through long waveguides.
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Affiliation(s)
- P Rath
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
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Affiliation(s)
- R Singh
- Department of General Surgery, T N Medical College & B Y L Nair Ch Hospital, Mumbai, India.
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Brognaro E, Ghods A, Feinstein D, Glick R, Connolly KJ, Meetze K, Boudrow A, Gyuris J, Han M, Hingtgen S, Figueiredo JL, Farrar C, Farrar C, Deubgen M, Martinez-Quintanilla J, Bhere D, Shah K, Marino AM, Lang SS, Boucher K, Sievert AJ, Madsen PJ, Slaunwhite E, Brewington D, Storm PB, Resnick AC, Poon C, Wu W, Pontifex C, Al-Najjar M, Artee Luchman H, Chesnelong C, Chan J, Weiss S, Gregory Cairncross J, Blough M, Brennan PM, Baily J, Diaz M, Ironside JW, Sansom O, Brunton V, Frame M, Tome CML, Miller LD, Debinski W, Borges AR, Larrubia PL, Marques JMB, Cerdan SG, Ozawa T, Huse JT, Squatrito M, Holland EC, Lee MH, Amlin-Van Schaick J, Broman K, Reilly K, Miller CR, Vitucci M, Bash R, White KK, Schmid RS, Pham CD, Flores C, Snyder D, Bigner DD, Sampson JH, Mitchell DA, Lal B, Rath P, Ajala O, Goodwin RC, Mughal S, Laterra JJ, Corwin D, Holdsworth C, Stewart R, Baldock A, Rockne R, Swanson K, Corwin D, Holdsworth C, Stewart R, Baldock A, Rockne R, Swanson K, Mikheev AM, Ramakrishna R, Stoll EA, Mikheeva SA, Beyer RP, Born D, Rockhill JK, Silber JR, Horner PJ, Rostomily R, Higgins DM, Wang R, Schroeder M, Carlson B, Yamada R, Meyer FB, Sarkaria JN, Henley JR, Parney IF, Chae M, Zhang L, Peterson TE, Schroeder MA, Sarkaria JN. LAB-TUMOR MODELS (IN VIVO/IN VITRO). Neuro Oncol 2012. [DOI: 10.1093/neuonc/nos241] [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: 11/14/2022] Open
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He H, Emmett MR, Marshall AG, Ji Y, Conrad CA, Priebe W, Colman H, Lang FF, Madden TL, Kristoffersen K, Stockhausen MT, Poulsen HS, Binder ZA, Orr B, Lim M, Weingart JD, Brem H, Olivi A, Riggins GJ, Gallia GL, Litofsky NS, Miller DC, Rath P, Anthony DC, Feng Q, Franklin C, Pei L, Free A, Kirk MD, Shi H, Timmer M, Theiss H, Juerchott K, Ries C, Paron I, Franz W, Selbig J, Guo K, Tonn JC, Schichor C, Zhou YH, Hu Y, Pioli PD, Rajneesh K, Limoli CL, Yu L, Hess KR, Linskey ME, Faber F, Guo K, Jaeger D, Thorsteinsdottir J, Albrecht V, Tonn JC, Schichor C, Price R, Song J, Zimmerman P, Duale H, Rivera A, Kaur B, Parada L, Cook C, Chiocca EA, Kwon CH, Munoz DM, Guha A, Estrada-Bernal A, Van Brocklyn JR, Gu C, Mahasenan KV, Joshi K, Gupta S, Mattson A, Li C, Nakano I, Chi AS, Rheinbay E, Wakimoto H, Gillespie S, Kasif S, Rabkin SD, Martuza RL, Bernstein BE, Skirboll SL, Wurdak H, Zhu S, Romero A, Lorger M, Watson J, Chiang CY, Zhang J, Natu VS, Lairson LL, Walker JR, Trussell CM, Harsh GR, Vogel H, Felding-Habermann B, Orth AP, Miraglia LJ, Rines DR, Schultz PG, Hide T, Takezaki T, Nakamura H, Makino K, Kuratsu JI, Kondo T, Yao J, Kim YW, Koul D, Almeida JS, Weinstein JN, Alfred Yung WK, Joshi K, Miyazaki T, Chaudhury AR, Nakano I, Wong AJ, Del Vecchio C, Mitra S, Han SY, Holgado-Madruga M, Gupta P, Golebiewska A, Brons NH, Bjerkvig R, Niclou SP, Ramm P, Vollmann-Zwerenz A, Beier C, Aigner L, Bogdahn U, Kalbitzer HR, Hau P, Sanzey M, Golebiewska A, Vallar L, Niclou SP, Tamura K, Aoyagi M, Ando N, Ogishima T, Wakimoto H, Yamamoto M, Ohno K, Perin A, Fung KH, Longatti P, Guiot MC, Del Maestro RF, Rossi S, Stechishin O, Weiss S, Stifani S, Goodman L, Gao F, Gumin J, Ezhilarasan R, Love P, George A, Colman H, Lang F, Aldape K, Sulman EP, Soeda A, Lee DH, Shaffrey ME, Oldfield EH, Park DM, Dietrich J, Han R, Noble M, Yang MY, Liu X, Madhankumar AB, Sheehan J, Slagle-Webb B, Connor JR, Fu J, Shen RJ, Colman H, Lang FF, Alfred Yung WK, Koul D, Kaluzova M, Machaidze R, Nduom ENK, Burden CT, Hadjipanayis CG, Lei L, Sonabend A, Guarnieri P, Ludwig T, Rosenfeld S, Bruce J, Canoll P, Vaillant BD, Bhat K, Balasubramaniyam V, Wang S, Gumin J, Sulman E, Lang F, Aldape K, Colman H, Sulman EP, Ezhilarasan R, Goodman LD, Love PN, George A, Aldape K, Soules M, Zhu T, Flack C, Talsma C, Hamm L, Muraszko K, Fan X, Aoyagi M, Matsuoka Y, Tamura K, Ando N, Kawano Y, Ohno K, Kobayashi D, Kumagai J, Frank RT, Najbauer J, Aboody KS, Aboody KS, Najbauer J, Metz M, Garcia E, Aramburo S, Valenzuela V, Gutova M, Annala AJ, Barish M, Danks M, Kim SU, Portnow J, Hofstetter C, Gursel D, Mubita L, Holland E, Boockvar J, Monje M, Freret M, Masek M, Edwards MS, Fisher PG, Vogel H, Beachy P. Stem Cells. Neuro Oncol 2010. [DOI: 10.1093/neuonc/noq116.s18] [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: 11/12/2022] Open
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Rath P, Panda UC, Bhatta D, Sahu KC. Use of sequential leaching, mineralogy, morphology and multivariate statistical technique for quantifying metal pollution in highly polluted aquatic sediments--a case study: Brahmani and Nandira Rivers, India. J Hazard Mater 2009; 163:632-44. [PMID: 18762380 DOI: 10.1016/j.jhazmat.2008.07.048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2007] [Revised: 05/22/2008] [Accepted: 07/04/2008] [Indexed: 05/02/2023]
Abstract
The particle size distribution, geochemical composition and sequential leaching of metals (Fe, Mn, Ni, Cu, Co, Cr, Pb, Zn and Cd) are carried out in core sediments (<88 microm) from the Brahmani and Nandira Rivers, India. To confirm the contamination of downstream sediments by fly ash, mineralogical and morphological characterizations were carried out. High environmental risk of Co, Pb and Ni is due to their higher availability in exchangeable fraction. The metals like Zn, Cu and Mn represent an appreciable portion in the carbonate phase. Metals such as Zn, Pb, Cd, Co and Ni are associated with reducible phase may be due to adsorption. The organic bound Cu, Zn, and Pb seem to be second dominant fraction among non-lithogenous in Nandira sediments. Factor analysis data reveals that textural parameters, Fe-Mn oxy/hydroxides, organic precipitation and coal fly ash disposals, are individually responsible for the enrichment of heavy metals. The relationships among the stations are highlighted by cluster analysis to identify the contamination levels.
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Affiliation(s)
- P Rath
- Department of Chemistry, KIIT (Kalinga Institute of Industrial Technology) University, Bhubaneswar 751024, Orissa, India.
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Baral S, Das S, Chaudhury GR, Swamy Y, Rath P. Adsorption of Cr(VI) using thermally activated weed Salvinia cucullata. Chemical Engineering Journal 2008; 139:245-255. [DOI: 10.1016/j.cej.2007.07.090] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
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Baral SS, Das SN, Rath P, Roy Chaudhury G, Swamy YV. Removal of Cr(VI) from aqueous solution using waste weed, Salvinia cucullata. Chemistry and Ecology 2007; 23:105-117. [DOI: 10.1080/02757540701197697] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
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Saner F, Gensicke J, Rath P, Fruhauf N, Gu Y, Paul A, Radtke A, Malagó M, Broelsch C. Safety Profile of Concomitant Use of Caspofungin and Cyclosporine or Tacrolimus in Liver Transplant Patients. Infection 2006; 34:328-32. [PMID: 17180587 DOI: 10.1007/s15010-006-5657-8] [Citation(s) in RCA: 34] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Accepted: 05/29/2006] [Indexed: 11/30/2022]
Abstract
BACKGROUND Caspofungin is the first substance of a new class of antifungal agents, the echinocandins that interfere with fungal cell wall synthesis by inhibition of glucan synthesis. Alanine aminotransferase (ALT) elevations were seen in phase I studies of patients receiving caspofungin and cyclosporine A (CyA). Actually, there is no information regarding hepatotoxicity in liver transplant patients treated concomitantly with caspofungin and immunosuppressant agents like CyA or tacrolimus (TAC). PATIENTS AND METHODS We conducted a retrospective study in 12 liver transplant patients (9 patients Child C, 3 patients acute liver failure) to assess the hepatic safety of simultaneous administration of caspofungin with CyA or TAC. Caspofungin was administered as first-line agent to patients for a 2-week period with either proofed invasive fungal infection (IFI) (n = 4), IFI-probable (n = 4), and IFI-possible (n = 4). All patients received concomitantly CyA or TAC as immunosuppressant agent. RESULTS Two patients died within the first 10 days after start of treatment, caused by gram-negative rods. All other ten patients completed the 14-day treatment period. No liver enzyme elevation was recorded in these patients and administration of caspofungin with CyA or TAC was well tolerated without hepatotoxicity. CONCLUSION The concomitant use of caspofungin with CyA or TAC in liver transplant patients is safe and seemed to be without hepatotoxic effect.
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Affiliation(s)
- F Saner
- Dept. of General Surgery and Transplantation, University Essen, Hufelandstr. 55, 45122, Essen, Germany.
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Arora R, Saha A, Malhotra D, Rath P, Kar P, Bamezai R. Promoter and intron-1 region polymorphisms in the IFNG gene in patients with hepatitis E. Int J Immunogenet 2006; 32:207-12. [PMID: 15932627 DOI: 10.1111/j.1744-313x.2005.00512.x] [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] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Allelic and genotype variations in the promoter region and the dinucleotide (CA)(n) repeat region in intron 1 of the interferon-g (IFNG) gene were analysed by direct sequencing and simple sequence length polymorphism (SSLP), respectively, in patients with acute hepatitis, and the prevalence was compared with that in healthy controls. Our results showed a significant association of heterozygous genotypes (CA)12/(CA)14 and (CA)12/(CA)16 in intron 1 of the IFNG gene in all categories of patients with acute hepatitis, classified on the basis of presence or absence of hepatitis E virus (HEV), in comparison with healthy controls. A novel polymorphism, -288 A-->T [from the translational start site, as per Human Genome Organization (HUGO) nomenclature], in the promoter region of the IFNG gene leading to a loss of the consensus domain for the interferon-stimulated response element (ISRE), as predicted by in silico analysis, was observed in 12.5% of patients with acute HEV infection. However, no significant difference in allele or genotype frequency was observed for the -288 promoter polymorphism, although the heterozygous -288 A/T genotype showed a moderate risk in patients with acute HEV infection alone (P = 0.29, odds ratio = 1.964, confidence interval = 0.46-8.45). The data suggest that the genotype at intron 1 of IFNG might affect susceptibility to acute hepatitis in HEV infection, which warrants further elucidation in a larger sample and also functional studies.
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Affiliation(s)
- R Arora
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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Shtoyerman-Chen R, Friedman E, Figer A, Carmel M, Patael Y, Rath P, Fidder HH, Bar-Meir S, Theodor L. The I1307K APC polymorphism: prevalence in non-Ashkenazi Jews and evidence for a founder effect. Genet Test 2002; 5:141-6. [PMID: 11551102 DOI: 10.1089/109065701753145628] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A missense mutation within the APC gene, I1307K, was described in Ashkenazi individuals at risk for colorectal cancer (CRC) and in the general population. The anecdotal reporting of the occurrence of this mutation in some non-Ashkenazi individuals led us to hypothesize that within the Jewish people, the I1307K polymorphism may reflect a founder mutation, and that the mutation is not restricted to ethnic Ashkenazis. To test that notion, and to establish the occurrence rate of the I1307K polymorphism in non-Ashkenazi Jewish populations, we screened Iraqi and Moroccan Jews and consecutive Jewish CRC patients and performed haplotype analysis with APC-linked markers in two I1307K carrier families. We analyzed Jewish individuals: 210 Moroccans, 160 Iraqis, 148 Ashkenazi, and 349 CRC patients (227 Ashkenazi and 122 non-Ashkenazi). The mutation detection scheme included PCR followed by denaturing gradient gel electrophoresis (DGGE) or modified restriction analysis (MRA). Haplotypes were assessed using three intragenic and three flanking markers. The I1307K polymorphism was detected in 29/227 Ashkenazi (12.8%), 2/122 (1.6%) non-Ashkenazi CRC patients, and in 2 individuals each (approximately 1%) within the Moroccan and Iraqi populations. Allelic pattern analysis in all our I1307K carriers, revealed a common haplotype for the three intragenic markers tested, in all mutation carriers, regardless of ethnic origin. The I1307K polymorphism, therefore, exists in all ethnic Jewish populations: Ashkenazi and non-Ashkenazi, with or without colon cancer. Jewish I1307K mutation carriers share a common allelic pattern with APC-linked markers. This strongly supports the notion of a founder mutation for I1307K.
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Affiliation(s)
- R Shtoyerman-Chen
- Department of Gastroenterology, Chaim Sheba Medical Center, Tel-Hashomer, Israel.
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Udolph G, Rath P, Chia W. A requirement for Notch in the genesis of a subset of glial cells in the Drosophila embryonic central nervous system which arise through asymmetric divisions. Development 2001; 128:1457-66. [PMID: 11262244 DOI: 10.1242/dev.128.8.1457] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [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: 11/20/2022]
Abstract
In the Drosophila central nervous system (CNS) glial cells are known to be generated from glioblasts, which produce exclusively glia or neuroglioblasts that bifurcate to produce both neuronal and glial sublineages. We show that the genesis of a subset of glial cells, the subperineurial glia (SPGs), involves a new mechanism and requires Notch. We demonstrate that the SPGs share direct sibling relationships with neurones and are the products of asymmetric divisions. This mechanism of specifying glial cell fates within the CNS is novel and provides further insight into regulatory interactions leading to glial cell fate determination. Furthermore, we show that Notch signalling positively regulates glial cells missing (gcm) expression in the context of SPG development.
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Affiliation(s)
- G Udolph
- Developmental Neurobiology Laboratory, Institute of Molecular and Cell Biology, 117609 Singapore
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Chen-Shtoyerman R, Figer A, Fidder HH, Rath P, Yeremin L, Bar Meir S, Friedman E, Theodor L. The frequency of the predominant Jewish mutations in BRCA1 and BRCA2 in unselected Ashkenazi colorectal cancer patients. Br J Cancer 2001; 84:475-7. [PMID: 11207040 PMCID: PMC2363769 DOI: 10.1054/bjoc.2000.1598] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is presently unclear whether carriers of BRCA1 mutations have an increased risk for colorectal cancer (CRC). To gain insight into this issue, 225 unselected Ashkenazi Jewish CRC patients were tested for the presence of the three common Jewish BRCA1/2 germline mutations: 185delAG and 5382insC (BRCA1) and 6174delT (BRCA2). A total of four carriers was found (4/225, 1.78%). This frequency is similar to the estimated normal Ashkenazi population frequency, thus suggesting that these specific mutations do not contribute to CRC predisposition.
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Affiliation(s)
- R Chen-Shtoyerman
- Gastroenterology Institute, Chaim Sheba Medical Center, Tel-Hashomer, 52621, Israel
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Lass-Flörl C, Rath P, Niederwieser D, Kofler G, Würzner R, Krezy A, Dierich MP. Aspergillus terreus infections in haematological malignancies: molecular epidemiology suggests association with in-hospital plants. J Hosp Infect 2000; 46:31-5. [PMID: 11023720 DOI: 10.1053/jhin.2000.0799] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [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: 11/11/2022]
Abstract
During a three-year period nine patients with haematological diseases after myeloablative chemotherapy died from invasive fungal infections caused by Aspergillus terreus. The hospital inanimate environment was monitored and A. terreus was cultured from potted plants in the vicinity of the patients. The patients (N = 14) and the environmental isolates (N = 2) were fingerprinted by RAPD-PCR with four different primers. Based on RAPD patterns the patients' isolates were differentiated into five different types; the environmental isolates represented two types. The isolates of four patients were identical to those found in the environment. Five additional patients were infected by RAPD types not found in the environment. One patient was infected with two different types. The data indicate a hospital-acquired infection in many of the patients and underline the need for careful environmental monitoring of units in which high-risk patients are housed.
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Affiliation(s)
- C Lass-Flörl
- Institute of Hygiene, University of Innsbruck, Austria.
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Tichler T, Ghodsizade E, Katz A, Rath P, Berger R, Brenner H. [Dose-intensive chemotherapy with continuous infusion 5-fluorouracil]. Harefuah 1999; 137:387-90, 430. [PMID: 11419042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
54 patients with advanced malignancy refractory to chemotherapy were studied to evaluate efficacy and toxicity of continuous infusion of 5-fluorouracil (5FU) given for 3 weeks. We report results of the first 156 courses given in combination with other drugs. 19 (37%) of the 54 responded, including 3 (6%) with complete response. Toxicity was acceptable, with mucositis in 13 (26%) and 3 (6%) with grade II-III toxicity. Results and toxicity profile were compatible with further disease-oriented studies using this dose-intensive program.
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Liu X, Lee MJ, Coleman M, Rath P, Nilsson A, Fischer WB, Bizounok M, Herzfeld J, Karstens WF, Raap J, Lugtenburg J, Rothschild KJ. Detection of threonine structural changes upon formation of the M-intermediate of bacteriorhodopsin: evidence for assignment to Thr-89. Biochim Biophys Acta 1998; 1365:363-72. [PMID: 9711293 DOI: 10.1016/s0005-2728(98)00088-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The behavior of threonine residues in the bacteriorhodopsin (bR) photocycle has been investigated by Fourier transform infrared difference spectroscopy. L-Threonine labeled at the hydroxyl group with 18O (L-[3-(18)O]threonine) was incorporated into bR and the bR-->M FTIR difference spectra measured. Bands are assigned to threonine vibrational modes on the basis of 18O induced isotope frequency shifts and normal mode calculations. In the 3500 cm-1 region, a negative band is assigned to the OH stretch of threonine. In the 1125 cm-1 region, a negative band is assigned to a mixed CH3 rock/CO stretch mode. The frequency of both these bands indicates the presence of at least one hydrogen bonded threonine hydroxyl group in light adapted bR which undergoes a change in structure by formation of the M intermediate. Spectral changes induced by the substitution Thr-89-->Asn but not Thr-46-->Asn or Asp-96-->Asn are consistent with the assignment of these bands to Thr-89. These results along with another related study on the mutant Thr-89-->Asn indicate that the active site of bR includes Thr-89 and that its interaction with the retinylidene Schiff base and Asp-85 may play an important role in regulating the color of bacteriorhodopsin and the transfer of a proton to the Schiff base.
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Affiliation(s)
- X Liu
- Physics Department, Boston University, MA 02215, USA
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Rath P, Delange F, Degrip WJ, Rothschild KJ. Hydrogen bonding changes of internal water molecules in rhodopsin during metarhodopsin I and metarhodopsin II formation. Biochem J 1998; 329 ( Pt 3):713-7. [PMID: 9445403 PMCID: PMC1219097 DOI: 10.1042/bj3290713] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Rhodopsin is a 7-helix, integral membrane protein found in the rod outer segments, which serves as the light receptor in vision. Light absorption by the retinylidene chromophore of rhodopsin triggers an 11-cis-->all-trans isomerization, followed by a series of protein conformational changes, which culminate in the binding and activation of the G-protein transducin by the metarhodopsin II (Meta II) intermediate. Fourier transform IR difference spectroscopy has been used to investigate the structural changes that water, as well as other OH- and NH-containing groups, undergo during the formation of the metarhodopsin I (Meta I) and Meta II intermediates. Bands associated with the OH stretch modes of water are identified by characteristic downshifts upon substitution of H2(18)O for H2O. Compared with earlier work, several negative bands associated with water molecules in unphotolysed rhodopsin were detected, which shift to lower frequencies upon formation of the Meta I and Meta II intermediates. These data indicate that at least one water molecule undergoes an increase in hydrogen bonding upon formation of the Meta I intermediate, while at least one other increases its hydrogen bonding during Meta II formation. Amino acid residue Asp-83, which undergoes a change in its hydrogen bonding during Meta II formation, does not appear to interact with any of the structurally active water molecules. Several NH and/or OH groups, which are inaccessible to hydrogen/deuterium exchange, also undergo alterations during Meta I and Meta II formation.
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Affiliation(s)
- P Rath
- Department of Physics and Molecular Biophysics Laboratory, Boston University, MA 02215, USA
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Abstract
A key step in visual transduction is the light-induced conformational changes of rhodopsin that lead to binding and activation of the G-protein transducin. In order to explore the nature of these conformational changes, time-resolved Fourier transform infrared spectroscopy was used to measure the kinetics of hydrogen/deuterium exchange in rhodopsin upon photoexcitation. The extent of hydrogen/deuterium exchange of backbone peptide groups can be monitored by measuring the integrated intensity of the amide II and amide II' bands. When rhodopsin films are exposed to D2O in the dark for long periods, the amide II band retains at least 60% of its integrated intensity, reflecting a core of backbone peptide groups that are resistant to H/D exchange. Upon photoactivation, rhodopsin in the presence of D2O exhibits a new phase of H/D exchange which at 10 degrees C consists of fast (time constant approximately 30 min) and slow (approximately 11 h) components. These results indicate that photoactivation causes buried portions of the rhodopsin backbone structure to become more accessible.
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Affiliation(s)
- P Rath
- Department of Physics, Boston University, Massachusetts 02215, USA
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Abstract
A question of fundamental importance concerning the biosynthesis of integral membrane proteins is whether transmembrane secondary structure can insert spontaneously into a lipid bilayer. It has proven to be difficult to address this issue experimentally because of the poor solubility in aqueous solution of peptides and proteins containing these extremely hydrophobic sequences. We have identified a system in which the kinetics and thermodynamics of alpha-helix insertion into lipid bilayers can be studied systematically and quantitatively using simple spectroscopic assays. Specifically, we have discovered that a 36-residue polypeptide containing the sequence of the C-helix of the integral membrane protein bacteriorhodopsin exhibits significant solubility in aqueous buffers free of both detergents and denaturants. This helix contains two aspartic acid residues in the membrane-spanning region. At neutral pH, the peptide associates with lipid bilayers in a nonhelical and presumably peripheral conformation. With a pKa of 6.0, the peptide inserts into the bilayer as a transbilayer alpha-helix. The insertion reaction proceeds rapidly at room temperature and is fully reversible.
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Affiliation(s)
- J F Hunt
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511, USA.
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Russell TS, Coleman M, Rath P, Nilsson A, Rothschild KJ. Threonine-89 participates in the active site of bacteriorhodopsin: evidence for a role in color regulation and Schiff base proton transfer. Biochemistry 1997; 36:7490-7. [PMID: 9200698 DOI: 10.1021/bi970287l] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [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: 02/04/2023]
Abstract
Bacteriorhodopsin (bR) functions as a light-driven proton pump in the purple membrane of Halobacterium salinarium. A major feature of bR is the existence of an active site which includes a retinylidene Schiff base and amino acid residues Asp-85, Asp-212, and Arg-82. This active site participates in proton transfers and regulates the visible absorption of bacteriorhodopsin and its photointermediates. In this work we find evidence that Thr-89 also participates in this active site. The substitution Thr-89 --> Asn (T89N) results in changes in the properties of the all-trans retinylidene chromophore of light-adapted bR including a redshift of the visible lambda(max) and a downshift in C=N and C=C stretch frequencies. Changes are also found in the M and N intermediates of the T89N photocycle including shifts in lambda(max), a downshift of the Asp-85 carboxylic acid C=O stretch frequency by 10 cm(-1), and a 3-5-fold decrease in the rate of formation of the M intermediate. In contrast, the properties of the 13-cis retinylidene chromophore of dark-adapted T89N as well as the K and L intermediates of the T89N photocycle are similar to the wild-type bacteriorhodopsin. These results are consistent with an interaction of the hydroxyl group of Thr-89 with the protonated Schiff base of light-adapted bR and possibly the N intermediate but not the 13-cis chromophore of dark-adapted bR or the K and L intermediates. Thr-89 also appears to influence the rate of Schiff base proton transfer to Asp-85 during formation of the M intermediate, possibly through an interaction with Asp-85. In contrast, the hydroxyl group of Thr-89 is not obligatory for proton transfer from Asp-96 to the Schiff base during formation of the N intermediate.
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Affiliation(s)
- T S Russell
- Physics Department, Boston University, Massachusetts 02215, USA
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Rath P, Spudich E, Neal DD, Spudich JL, Rothschild KJ. Asp76 is the Schiff base counterion and proton acceptor in the proton-translocating form of sensory rhodopsin I. Biochemistry 1996; 35:6690-6. [PMID: 8639619 DOI: 10.1021/bi9600355] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [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: 02/01/2023]
Abstract
Both sensory rhodopsin I, a phototaxis receptor, and bacteriorhodopsin, a light-driven proton pump, have homologous residues which have been identified as critical for bacteriorhodopsin functioning. This includes Asp76, which in the case of bacteriorhodopsin (Asp85) functions as both the Schiff base counterion and the proton acceptor. Sensory rhodopsin I exists in a pH dependent equilibrium between two different forms in the absence of its transducer protein HtrI. At pH below 7, it exists primarily in a blue form (lambda max = 587 nm) which functions as a phototaxis signal transducer when complexed to HtrI, while at higher pH, it converts to a purple proton-transporting form similar to bacteriorhodopsin (lambda max = 550 nm). We report ATR-FTIR difference spectra obtained from both low- and high-pH forms of purified sensory rhodopsin I reconstituted into lipid vesicles. The low-pH species has an ethylenic C = C stretch mode at 1520 cm-1 which shifts to 1526 cm-1 in the high-pH form. No frequency shift was found for the mutant D76N, in agreement with visible absorption measurements. Weak negative/positive bands at 1763/1751 cm-1 previously assigned to a perturbation of the C = O stretch mode of Asp76 during S373 formation in the low-pH form are replaced by a single intense positive band near 1749 cm-1 in the high-pH form. These results along with the effects of H/D exchange show that Asp76 is protonated in the signal-transducing form of sensory rhodopsin I and is ionized and functions as the counterion and Schiff base proton acceptor in the proton-transporting high-pH form of sensory rhodopsin I similar to bacteriorhodopsin.
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Affiliation(s)
- P Rath
- Department of Physics, Boston University, Boston, Massachusetts 02215, USA
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34
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Ludlam CF, Arkin IT, Liu XM, Rothman MS, Rath P, Aimoto S, Smith SO, Engelman DM, Rothschild KJ. Fourier transform infrared spectroscopy and site-directed isotope labeling as a probe of local secondary structure in the transmembrane domain of phospholamban. Biophys J 1996; 70:1728-36. [PMID: 8785331 PMCID: PMC1225141 DOI: 10.1016/s0006-3495(96)79735-7] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [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: 02/02/2023] Open
Abstract
Phospholamban is a 52-amino acid residue membrane protein that regulates Ca(2+)-ATPase activity in the sarcoplasmic reticulum of cardiac muscle cells. The hydrophobic C-terminal 28 amino acid fragment of phospholamban (hPLB) anchors the protein in the membrane and may form part of a Ca(2+)-selective ion channel. We have used polarized attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy along with site-directed isotope labeling to probe the local structure of hPLB. The frequency and dichroism of the amide I and II bands appearing at 1658 cm-1 and 1544 cm-1, respectively, show that dehydrated and hydrated hPLB reconstituted into dimyristoylphosphatidycholine bilayer membranes is predominantly alpha-helical and has a net transmembrane orientation. Specific local secondary structure of hPLB was probed by incorporating 13C at two positions in the protein backbone. A small band seen near 1614 cm-1 is assigned to the amide I mode of the 13C-labeled amide carbonyl group(s). The frequency and dichroism of this band indicate that residues 39 and 46 are alpha-helical, with an axial orientation that is approximately 30 degrees relative to the membrane normal. Upon exposure to 2H2O (D2O), 30% of the peptide amide groups in hPLB undergo a slow deuterium/hydrogen exchange. The remainder of the protein, including the peptide groups of Leu-39 and Leu-42, appear inaccessible to exchange, indicating that most of the hPLB fragment is embedded in the lipid bilayer. By extending spectroscopic characterization of PLB to include hydrated, deuterated as well as site-directed isotope-labeled hPLB films, our results strongly support models of PLB that predict the existence of an alpha-helical hydrophobic region spanning the membrane domain.
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Affiliation(s)
- C F Ludlam
- Department of Physics, Boston University, Massachusetts 02215, USA
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35
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Nilsson A, Rath P, Olejnik J, Coleman M, Rothschild KJ. Protein conformational changes during the bacteriorhodopsin photocycle. A Fourier transform infrared/resonance Raman study of the alkaline form of the mutant Asp-85-->Asn. J Biol Chem 1995; 270:29746-51. [PMID: 8530365 DOI: 10.1074/jbc.270.50.29746] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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: 01/31/2023] Open
Abstract
Bacteriorhodopsin is a light-driven proton pump, which undergoes a photocycle consisting of several distinct intermediates. Previous studies have established that the M-->N step of this photocycle involves a major conformational change of membrane embedded alpha-helices. In order to further investigate this conformational change, we have studied the photocycle of the high pH form of the mutant Asp-85-->Asn (D85Nalk). In contrast to wild type bacteriorhodopsin, D85Nalk has a deprotonated Schiff base and a blue-shifted absorption near 410 nm, yet it still transports protons in the same direction as wild type bacteriorhodopsin (Tittor, J., Schweiger, U., Oesterhelt, D. and Bamberg, E. (1994) Biophys. J., 67, 1682-1690). Resonance Raman spectroscopy of D85Nalk and D85Nalk regenerated with retinal labeled at the C-15 position with deuterium reveals the existence of an all-trans configuration of the chromophore. Fourier transform infrared difference spectroscopy shows that the photocycle of this light-adapted form involves similar events as the wild type bacteriorhodopsin photocycle including the M-->N protein conformational change. These results help to explain the ability of D85Nalk to transport protons and demonstrate that the M-->N conformational change can occur even in the photocycle of an unprotonated Schiff base form of bacteriorhodopsin.
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Affiliation(s)
- A Nilsson
- Physics Department, Boston University, Massachusetts 02215, USA
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36
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Coleman M, Nilsson A, Russell TS, Rath P, Pandey R, Rothschild KJ. Asp 46 can substitute Asp 96 as the Schiff base proton donor in bacteriorhodopsin. Biochemistry 1995; 34:15599-606. [PMID: 7492563 DOI: 10.1021/bi00047a027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [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: 01/25/2023]
Abstract
Bacteriorhodopsin functions as a light-driven proton pump in the purple membrane of Halobacterium salinarium. A variety of studies have established that a proton is transferred over an approximately 10 A distance from Asp 96 to the retinylidene Schiff base during the M --> N transition of the bR photocycle. In order to further explore the mechanism of this Schiff base reprotonation, we compared the properties of the double mutant Thr 46 --> Asp/Asp 96 --> Asn (T46D/D96N), the single mutants Asp 96 --> Asn (D96N) and Thr 46 --> Asp (T46D), and wild-type bR. In contrast to D96N, which exhibits a very slow M decay, T46D/D96N has an M decay close to that of wild-type bR. FTIR difference spectroscopy detects bands in the carboxyl and carboxylate stretch region of T46D/D96N consistent with the deprotonation of Asp 46 during the M --> N transition. In addition, bands associated with structural changes of Asn 96 in the mutant D96N are absent in T46D/D96N. Resonance Raman spectroscopy provides evidence that both T46D/D96N and T46D have a long-lived N-like species in their photocycles. These data demonstrate that Asp 46 can substitute for Asp 96 as the proton donor group in the reprotonation pathway of the Schiff base during the M --> N transition. However, N decay is delayed in comparison to wild-type bR. This may be due to a partial block in the proton pathway leading from the cytoplasmic medium to Asp 46.
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Affiliation(s)
- M Coleman
- Physics Department, Boston University, Massachusetts 02215, USA
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37
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Rath P. Palama Settlement: 100 years of serving a neighborhood's needs. Hawaii Med J 1995; 54:774-5. [PMID: 8586547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The founding of Palama Settlement brought to those who might not be able to afford it public health nurses for maternal care and nutrition, well-baby clinics, tuberculosis clinics, medical and dental clinics, and eventually major support of medical needs during and after the attack on Pearl Harbor. Palama Settlement celebrates its centennial year with many of its early functions assumed by state and private organizations, but it is prepared to enter the next 100 years of service to the community. Palama was founded by James Arthur Rath with the purpose of serving the community; many people today remember their childhood and Palama Settlement.
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Abstract
Bovine rod rhodopsin and membrane-carboxyl group mutants are expressed using the recombinant baculovirus expression system. Biosynthesis of wild-type and the mutant D83N is normal. The mutations E122L and E134D/R affect glycosylation and translocation. After regeneration, purification and reconstitution in retina lipids a wild-type photosensitive pigment with spectral and photolytic properties identical to native bovine rod rhodopsin is generated. Only the mutations D83N and E122L affect the spectral properties and then only slightly. All mutations induce a shift in the Meta I<==>Meta II equilibrium towards Meta I (E134D/R) or Meta II (D83N, E122L). FT-IR analysis shows that the mutation E134D/R does not significantly affect the carboxyl-vibration region but, in particular in the case of E134R, affects secondary structural changes upon Meta II formation. E122L also has an effect on secondary structural changes and in addition eliminates a negative band at 1728 cm-1. The mutation D83N removes a pair of negative/positive bands from the carboxyl-vibration region, indicating that Asp83 stays protonated upon formation of Meta II but undergoes a change in hydrogen bonding.
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Affiliation(s)
- G L DeCaluwé
- Department of Biochemistry F.M.W., University of Nijmegen, The Netherlands
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39
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Zwas ST, Goshen E, Rath P, Brenner H, Klein E, Ben-Ari G. Detection efficiency of colorectal carcinoma recurrence using technetium pertechnetate-anti-carcinoembryonic antigen monoclonal antibody BW 431/26. Cancer 1995; 76:215-22. [PMID: 8625094 DOI: 10.1002/1097-0142(19950715)76:2<215::aid-cncr2820760209>3.0.co;2-a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND A new anti-carcinoembryonic antigen (CEA) antibody, BW 431/26 (Scintimun, Behring-Werke, Marburg, Germany), labeled with technetium pertechnetate (Tc-99m), is an intact immunoglobulin G1 monoclonal antibody that has been used to image colorectal cancer (CRC). This report is part of a prospective multicenter clinical trial initiated by the International Atomic Energy Agency to evaluate the role of this antibody in radioimmunoimaging of patients with suspected disease recurrence. METHODS A group of 31 consecutive patients underwent radioimmunoimaging with Tc-99m-BW 431/26 after resection of their primary CRC. Patient referral was based on either a persistent rise in serum CEA levels of unknown origin and/or questionable findings by other imaging studies. Whole-body planar scans and single photon emission computed tomography scans of selected body regions (e.g., chest, abdomen) were performed up to 24 hours after the intravenous antibody injection. Pathologic antibody concentration localizations by radioimmunoimaging were correlated with surgical, clinical, and other imaging modality findings to validate the accuracy of radioimmunoimaging in detecting CRC recurrence. RESULTS A total of 75 detected tumoral lesions was evaluated: 26 of 75 were of known origin (36%), and 49 of 75 were of unknown origin (65%). There were four true-negative lesions, one false-negative lesion, and no false-positive lesions; all others were true-positive lesions. Sensitivity was 96.8%, specificity 100%, and accuracy 98.6%. The study was easy to perform, without untoward side effects on patients after antibody administration. CONCLUSIONS Anti-CEA antibody radioimmunoimaging is a highly reliable diagnostic procedure in detecting CRC recurrence and is useful especially for the diagnosis of patients with rising CEA blood levels of unknown origin, thereby significantly affecting patient management. Radioimmunoimaging should become part of the diagnostic workup of patients suspected of having CRC recurrence.
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Affiliation(s)
- S T Zwas
- Department of Nuclear Medicine, Chaim Sheba Medical Center, Tel Hashomer, Israel
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40
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Sonar S, Marti T, Rath P, Fischer W, Coleman M, Nilsson A, Khorana HG, Rothschild KJ. A redirected proton pathway in the bacteriorhodopsin mutant Tyr-57-->Asp. Evidence for proton translocation without Schiff base deprotonation. J Biol Chem 1994; 269:28851-8. [PMID: 7961844] [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: 01/28/2023] Open
Abstract
Light-driven proton pumping in bacteriorhodopsin involves deprotonation of the retinylidene Schiff base during M formation and reprotonation during N formation as key steps. This study reports on the spectroscopic characterization of the bacteriorhodopsin mutant Tyr-57-->Asp (Y57D). The results reveal that although formation of the M intermediate and Schiff base deprotonation is blocked, the mutant still exhibits a significant level of light-driven proton translocation. The photocycle of Y57D involves formation of K and L intermediates accompanied by the normal chromophore isomerization and changes in the hydrogen bonding of Asp-96 and Asp-115. However, an additional Asp residue deprotonates during formation of the L intermediate along with a transmembrane alpha-helical structural change that normally occurs upon N formation. We postulate that proton transport in Y57D occurs through a redirected pathway that does not involve the deprotonation of the Schiff base. Chromophore isomerization, which normally results in the transfer of a proton from the Schiff base to Asp-85, instead causes the deprotonation of Asp-57 in Y57D, most likely through an interaction involving Asp-212. This deprotonation of Asp-57 causes the release of a proton into the extracellular medium. Reprotonation of Asp-57 occurs through the Schiff base reprotonation pathway, which consists of a hydrogen-bonded network of residues spanning from Asp-96 to Asp-212. The results also indicate that the transmembrane alpha-helical structural changes observed during N formation (Rothschild, K.J., Marti, T., Sonar, S., He, Y.W., Rath, P., Fischer, W., Bousche, O., and Khorana, H. G. (1993) J. Biol. Chem. 268, 27046-27052) do not require deprotonation of Asp-96 or of the Schiff base.
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Affiliation(s)
- S Sonar
- Physics Department, Boston University, Massachusetts 02215
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41
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Sonar S, Marti T, Rath P, Fischer W, Coleman M, Nilsson A, Khorana H, Rothschild K. A redirected proton pathway in the bacteriorhodopsin mutant Tyr-57–>Asp. Evidence for proton translocation without Schiff base deprotonation. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)61985-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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42
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Rath P, Bovee-Geurts PH, DeGrip WJ, Rothschild KJ. Photoactivation of rhodopsin involves alterations in cysteine side chains: detection of an S-H band in the Meta I-->Meta II FTIR difference spectrum. Biophys J 1994; 66:2085-91. [PMID: 8075342 PMCID: PMC1275934 DOI: 10.1016/s0006-3495(94)81003-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [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: 01/28/2023] Open
Abstract
FTIR difference spectroscopy has been used to study the role of cysteine residues in the photoactivation of rhodopsin. A positive band near 2550 cm-1 with a low frequency shoulder is detected during rhodopsin photobleaching, which is assigned on the basis of its frequency and isotope shift to the S-H stretching mode of one or more cysteine residues. Time-resolved studies at low temperature show that the intensity of this band correlates with the formation and decay kinetics of the Meta II intermediate. Modification of rhodopsin with the reagent NEM, which selectively reacts with the SH groups of Cys-140 and Cys-316 on the cytoplasmic surface of rhodopsin, has no effect on the appearance of this band. Four other cysteine residues are also unlikely to contribute to this band because they are either thio-palmitylated (Cys-322 and Cys-323) or form a disulfide bond (Cys-110 and Cys-187). On this basis, it is likely that at least one of the four remaining cysteine residues in rhodopsin is structurally active during rhodopsin photoactivation. The possibility is also considered that this band arises from a transient cleavage of the disulfide bond between cysteine residues 110 and 187.
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Affiliation(s)
- P Rath
- Department of Physics, Boston University, Massachusetts 02215
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43
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Rath P, Olson KD, Spudich JL, Rothschild KJ. The Schiff base counterion of bacteriorhodopsin is protonated in sensory rhodopsin I: spectroscopic and functional characterization of the mutated proteins D76N and D76A. Biochemistry 1994; 33:5600-6. [PMID: 8180184 DOI: 10.1021/bi00184a032] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [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: 01/29/2023]
Abstract
Both sensory rhodopsin I (SR-I), a phototaxis receptor, and bacteriorhodopsin (BR), a light-driven proton pump, share residues which have been identified as critical for BR functioning. This includes Asp76, which in the case of bacteriorhodopsin (Asp85) functions both as the Schiff base counterion and proton acceptor. We found that substituting an Asn for Asp76 (D76N) in SR-I has no effect on its visible absorption unlike the analogous mutation (D85N) in BR which shifts the absorption to longer wavelengths. The mutated proteins D76N and D76A are also fully functional as phototaxis receptors in contrast to BR, where the analogous substitutions block proton transport. D76N was also found to exhibit a spectrally normal SR587-->S373 transition. However, FTIR difference spectroscopy reveals that two bands in the SR587-->S373 difference spectrum at 1766/1749 cm-1 (negative/positive), assigned to the C=O stretch mode of a carboxylic acid, disappear in D76N, although no changes are observed in the carboxylate region. In addition, the kinetics and yield of this photoreaction are altered. On this basis, it is concluded that, unlike Asp85 in bacteriorhodopsin, Asp76 is protonated in SR-I and undergoes an increase in its hydrogen bonding during the SR587-->S373 transition. This model accounts for the difference in color of SR-I and BR and the finding that Asn can substitute for Asp76 without greatly altering the SR-I phenotype. Interestingly, parallels exist between this residue and Asp83 in the visual receptor rhodopsin which has recently been found to exist in a protonated form and to undergo an almost identical change in hydrogen bonding during rhodopsin activation.
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Affiliation(s)
- P Rath
- Department of Physics, Boston University, Massachusetts 02215
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44
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Rothschild KJ, Marti T, Sonar S, He YW, Rath P, Fischer W, Khorana HG. Asp96 deprotonation and transmembrane alpha-helical structural changes in bacteriorhodopsin. J Biol Chem 1993; 268:27046-52. [PMID: 8262942] [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: 01/29/2023] Open
Abstract
The M-->N transition in the photocycle of bacteriorhodopsin involves the transfer of a proton from Asp96 to the retinylidene Schiff base, possibly through a network of hydrogen-bonded amino acid residues and water molecules (Rothschild, K. J., He, Y. W., Sonar, S., Marti, T., and Khorana, H. G. (1992) J. Biol. Chem. 267, 1615-1622). A conformational change of the protein backbone is also observed during this transition. In this work, we have investigated the effects of replacing the residue Thr46, which might be part of this chain, with an aspartic acid. Both Fourier transform infrared and resonance Raman spectroscopy show that the chromophore structure of this mutant (T46D) is normal. However, N formation is accelerated and N decay is significantly slowed compared to wild-type bacteriorhodopsin. This effect causes the N intermediate to accumulate under steady-state illumination thereby facilitating spectroscopic studies under normal pH conditions. Fourier transform infrared difference spectroscopy reveals that like native bacteriorhodopsin, N formation in T46D involves deprotonation of Asp96, reprotonation of the Schiff base, and a change in the backbone secondary structure. However, in contrast to bacteriorhodopsin, bands assigned to the C = O stretch mode of the carboxylic acid group of Asp96 are upshifted by 10 cm-1 reflecting a change in the Asp96 environment and a drop in its effective pKa throughout the photocycle. This change in the pKa can directly account for changes in the photocycle kinetics and indicates that Asp96 deprotonation/protonation are the rate limiting steps in the formation and decay of the N intermediate. By studying the effects of H/D exchange, evidence is found that the backbone structural changes involve transmembrane alpha-helices. It is proposed that these structural changes serve to modulate the local environment and protonation state of Asp96 during the photocycle and are also essential for formation of the proton conducting hydrogen bonded network which functions during Schiff base reprotonation.
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Affiliation(s)
- K J Rothschild
- Physics Department, Boston University, Massachusetts 02215
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45
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Rothschild KJ, Marti T, Sonar S, He YW, Rath P, Fischer W, Khorana HG. Asp96 deprotonation and transmembrane alpha-helical structural changes in bacteriorhodopsin. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74216-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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46
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Rath P, DeCaluwé LL, Bovee-Geurts PH, DeGrip WJ, Rothschild KJ. Fourier transform infrared difference spectroscopy of rhodopsin mutants: light activation of rhodopsin causes hydrogen-bonding change in residue aspartic acid-83 during meta II formation. Biochemistry 1993; 32:10277-82. [PMID: 8399169 DOI: 10.1021/bi00090a001] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.2] [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: 01/30/2023]
Abstract
Fourier transform infrared (FTIR) difference spectroscopy and site-directed mutagenesis have been used to investigate structural changes which occur during rhodopsin photoactivation at the level of individual amino acid residues. The rhodopsin-->bathorhodopsin FTIR difference spectra of the mutants Asp-83-->Asn (D83N) and Glu-134-->Asp (E134D) incorporated into membranes are similar to that of native rhodopsin in the photoreceptor membrane, demonstrating that the retinal chromophores of these mutants undergo a normal 11-cis to all-trans photoisomerization. Two bands assigned to the C = O stretching mode of Asp and/or Glu carboxylic acid groups are absent in the D83N rhodopsin-->metarhodopsin II FTIR difference spectrum. Corresponding changes are not observed in the carboxylate C = O stretching region. The most straightforward explanation is that the carboxylic acid group of Asp-83 remains protonated in rhodopsin and its bleaching intermediates but undergoes an increase in its hydrogen bonding during the metarhodopsin I-->metarhodopsin II transition. The mutant E134D produced a normal rhodopsin-->bathorhodopsin and rhodopsin-->metarhodopsin II difference spectrum, but a fraction of misfolded protein was observed, supporting earlier evidence that Glu-134 plays a role in proper protein insertion and/or folding in the membrane.
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Affiliation(s)
- P Rath
- Department of Physics, Boston University, Massachusetts 02215
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47
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Rath P, Marti T, Sonar S, Khorana HG, Rothschild KJ. Hydrogen bonding interactions with the Schiff base of bacteriorhodopsin. Resonance Raman spectroscopy of the mutants D85N and D85A. J Biol Chem 1993; 268:17742-9. [PMID: 8349659] [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: 01/30/2023] Open
Abstract
The bacteriorhodopsin (bR) mutants Asp-85-->Asn (D85N) and Asp-85-->Ala (D85A) have a red-shifted chromophore absorption and exhibit no proton pumping (Otto, H., Marti, T., Holz, M., Mogi, T., Stern, L., Engel, F., Khorana, H. G., and Heyn, M. P. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 1018-1022) consistent with the hypothesis that Asp-85 functions as a counterion and proton acceptor for the retinal Schiff base (Braiman, M. S., Mogi, T., Marti, T., Stern, L. J., Khorana, H. G., and Rothschild, K. J. (1988) Biochemistry 27, 8516-8520). Resonance Raman spectroscopy reveals that these mutants contain a mixture of all-trans and 13-cis/C = N syn chromophores, similar to dark-adapted purple membrane and acid-induced or deionized blue membrane. At high NaCl concentrations, both mutants adopt a predominantly all-trans chromophore structure similar to acid purple membrane. A comparison of the Schiff base C = NH+ stretch frequency (vC = N) and deuterium isotope shift for D85N, D85A as well as various forms of bR, including light-adapted bR, blue membrane, and acid purple membrane, provides information about hydrogen bonding interactions to the Schiff base. D85N has as strong a hydrogen bond as light-adapted bR despite the loss of the negative charge at residue 85. In contrast, D85A has a weaker hydrogen bond. These results can be explained if a direct interaction exists between the Schiff base and Asn-85 in D85N and between the Schiff base and a substituted water molecule in D85A. Many of the properties of wild type bR, D85N, D85A, blue membrane, and acid purple membrane can be explained on the basis of changes in the local hydrogen bonding near the Schiff base.
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Affiliation(s)
- P Rath
- Physics Department and Program in Cellular Biophysics, Boston University, Massachusetts 02215
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48
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Rath P, Marti T, Sonar S, Khorana H, Rothschild K. Hydrogen bonding interactions with the Schiff base of bacteriorhodopsin. Resonance Raman spectroscopy of the mutants D85N and D85A. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(17)46767-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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49
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Rath P, Krebs MP, He Y, Khorana HG, Rothschild KJ. Fourier transform Raman spectroscopy of the bacteriorhodopsin mutant Tyr-185-->Phe: formation of a stable O-like species during light adaptation and detection of its transient N-like photoproduct. Biochemistry 1993; 32:2272-81. [PMID: 8443170 DOI: 10.1021/bi00060a020] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [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: 01/30/2023]
Abstract
Near-infrared FT-Raman spectroscopy can be used to measure the vibrations of the bacteriorhodopsin (bR) chromophore without the disadvantage of conventional visible resonance Raman spectroscopy, where the visible excitation drives the bR photoreactions. We utilized this technique to investigate the light-dark adaptation of bacteriorhodopsin and the mutant Tyr-185-->Phe (Y185F) at room temperature in solution. Compared to wild-type bR, both the FT-Raman and resonance Raman spectra of the light-adapted Y185F displayed new features characteristic of the vibrations of the O intermediate. Light adaptation of Y185F was found to involve a 13-cis, C=N syn-->all-trans isomerization of the retinal chromophore which produces a species similar to bR570 and a second O-like species. Dark adaptation, which was much slower in Y185F compared to wild-type bR, involved a parallel decay of the bR570 and O-like species and resulted in a decreased all-trans:13-cis ratio compared to wild type. Further evidence for the existence of an O-like species in Y185F comes from pump-probe Raman difference spectroscopy, where a red pump beam is found to produce a species very similar to the N intermediate in the photocycle. This species is shown by stroboscopic Raman measurements to exist transiently even at high pH. We postulate that when the Y185F chromophore has an all-trans structure the effective pKa of Asp-85 and Asp-212 is elevated in Y185F due to the disruption of the Asp-212/Tyr-185 hydrogen bond, thereby accounting for the increased protonation of these residues in the O-like species.
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Affiliation(s)
- P Rath
- Physics Department, Boston University, Massachusetts 02215
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Berland J, Rocha P, Choussat A, Lefebvre T, Fernandez F, Rath P. Balloon mitral valvotomy by using the Twin-AT catheter: immediate results and complications in 110 patients. Cathet Cardiovasc Diagn 1993; 28:126-33. [PMID: 8448795 DOI: 10.1002/ccd.1810280207] [Citation(s) in RCA: 8] [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: 01/30/2023]
Abstract
Balloon mitral valvotomy, using a new Twin AT catheter (two balloons attached side by side over one shaft), was performed in 110 consecutive cases. The age of the patients ranged from 19-78 yr (mean 46 +/- 15). From a total of 94 females and 16 males, 23 of the patients (22%) had mitral valve calcification, 47 patients (46%) had atrial fibrillation, and 39 patients (37%) had mitral regurgitation (< +2). Twenty patients (18%) presented with restenosis following surgical commissurotomy. Total catheterization time was 101 +/- 26 min and the duration of the valvotomy procedure was 37 +/- 21 min in these cases. For the entire population, there was a significant reduction in mitral valve gradient (15 +/- 6 to 4.8 +/- 2.6 mmHg, p < .001), an increase in mitral valve area (MVA) (1.1 +/- 0.3 to 2.35 +/- 0.7 cm2, p < .001), and a decrease in mean pulmonary arterial pressure (31 +/- 12 to 26 +/- 11, p < .002) after the balloon mitral valvotomy. Sixteen patients (14%) developed significant left to right shunt, and in 22 patients (20%) mitral regurgitation increased moderately but without resulting in emergency valve replacement. There was one incidence of embolic episode and one pericardial tamponade. Adequate hemodynamic results (MVA > 1.5 cm2 and % increase in MVA > or = 50%) without major complications were obtained in 99 cases. In 9 patients with severely diseased valve (2 previous commissurotomy, one restenosis after balloon valvotomy), or small left ventricular cavity, insufficient results were obtained by the Twin-AT catheter.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Berland
- Service de Cardiologie, Hospital Charles Nicolle, Rouen, France
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