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Ma L, Ge Y, Brown J, Choi SC, Elshikha A, Kanda N, Terrell M, Six N, Garcia A, Mohamadzadeh M, Silverman G, Morel L. Dietary tryptophan and genetic susceptibility expand gut microbiota that promote systemic autoimmune activation. bioRxiv 2024:2024.01.16.575942. [PMID: 38293097 PMCID: PMC10827173 DOI: 10.1101/2024.01.16.575942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Tryptophan modulates disease activity and the composition of microbiota in the B6.Sle1.Sle2.Sle3 (TC) mouse model of lupus. To directly test the effect of tryptophan on the gut microbiome, we transplanted fecal samples from TC and B6 control mice into germ-free or antibiotic-treated non-autoimmune B6 mice that were fed with a high or low tryptophan diet. The recipient mice with TC microbiota and high tryptophan diet had higher levels of immune activation, autoantibody production and intestinal inflammation. A bloom of Ruminococcus gnavus (Rg), a bacterium associated with disease flares in lupus patients, only emerged in the recipients of TC microbiota fed with high tryptophan. Rg depletion in TC mice decreased autoantibody production and increased the frequency of regulatory T cells. Conversely, TC mice colonized with Rg showed higher autoimmune activation. Overall, these results suggest that the interplay of genetic and tryptophan can influence the pathogenesis of lupus through the gut microbiota.
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Affiliation(s)
- Longhuan Ma
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX
| | - Yong Ge
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX
| | - Josephine Brown
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL
| | - Seung-Chul Choi
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX
| | - Ahmed Elshikha
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL
| | - Nathalie Kanda
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL
| | - Morgan Terrell
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL
| | - Natalie Six
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX
| | - Abigail Garcia
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX
| | - Mansour Mohamadzadeh
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX
| | | | - Laurence Morel
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX
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Ma L, Terrell M, Brown J, Castellanos Garcia A, Elshikha A, Morel L. TLR7/TLR8 activation and susceptibility genes synergize to breach gut barrier in a mouse model of lupus. Front Immunol 2023; 14:1187145. [PMID: 37483626 PMCID: PMC10358848 DOI: 10.3389/fimmu.2023.1187145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 06/21/2023] [Indexed: 07/25/2023] Open
Abstract
Background Mounting evidence suggests that increased gut permeability, or leaky gut, and the resulting translocation of pathobionts or their metabolites contributes to the pathogenesis of Systemic Lupus Erythematosus. However, the mechanisms underlying the induction of gut leakage remain unclear. In this study, we examined the effect of a treatment with a TLR7/8 agonist in the B6.Sle1.Sle2.Sle3 triple congenic (TC) mouse, a spontaneous mouse model of lupus without gut leakage. Materials and methods Lupus-prone mice (TC), TC.Rag1-/- mice that lack B and T cells, and congenic B6 healthy controls were treated with R848. Gut barrier integrity was assessed by measuring FITC-dextran in the serum following oral gavage. Claudin-1 and PECAM1 expression as well as the extent of CD45+ immune cells, B220+ B cells, CD3+ T cells and CD11b+ myeloid cells were measured in the ileum by immunofluorescence. NKp46+ cells were measured in the ileum and colon by immunofluorescence. Immune cells in the ileum were also analyzed by flow cytometry. Results R848 decreased gut barrier integrity in TC but not in congenic control B6 mice. Immunofluorescence staining of the ileum showed a reduced expression of the tight junction protein Claudin-1, endothelial cell tight junction PECAM1, as well as an increased infiltration of immune cells, including B cells and CD11b+ cells, in R848-treated TC as compared to untreated control mice. However, NKp46+ cells which play critical role in maintaining gut barrier integrity, had a lower frequency in treated TC mice. Flow cytometry showed an increased frequency of plasma cells, dendritic cells and macrophages along with a decreased frequency of NK cells in R848 treated TC mice lamina propria. In addition, we showed that the R848 treatment did not induce gut leakage in TC.Rag1-/- mice that lack mature T and B cells. Conclusions These results demonstrate that TLR7/8 activation induces a leaky gut in lupus-prone mice, which is mediated by adaptive immune responses. TLR7/8 activation is however not sufficient to breach gut barrier integrity in non-autoimmune mice.
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Affiliation(s)
- Longhuan Ma
- Department of Microbiology, Immunology, and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Morgan Terrell
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Josephine Brown
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Abigail Castellanos Garcia
- Department of Microbiology, Immunology, and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Ahmed Elshikha
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Laurence Morel
- Department of Microbiology, Immunology, and Molecular Genetics, University of Texas Health San Antonio, San Antonio, TX, United States
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Abboud G, Choi SC, Zhang X, Park YP, Kanda N, Zeumer-Spataro L, Terrell M, Teng X, Nündel K, Shlomchik MJ, Morel L. Glucose Requirement of Antigen-Specific Autoreactive B Cells and CD4+ T Cells. J Immunol 2023; 210:377-388. [PMID: 36602759 PMCID: PMC9898175 DOI: 10.4049/jimmunol.2200325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 12/05/2022] [Indexed: 01/06/2023]
Abstract
The activation of lymphocytes in patients with lupus and in mouse models of the disease is coupled with an increased cellular metabolism in which glucose plays a major role. The pharmacological inhibition of glycolysis with 2-deoxy-d-glucose (2DG) reversed the expansion of follicular helper CD4+ T cells and germinal center B cells in lupus-prone mice, as well as the production of autoantibodies. The response of foreign Ags was however not affected by 2DG in these mice, suggesting that B and CD4+ T cell activation by autoantigens is uniquely sensitive to glycolysis. In this study, we tested this hypothesis with monoclonal B cells and CD4+ T cells specific for lupus-relevant autoantigens. AM14 Vκ8R (AM14) transgenic B cells are activated by IgG2a/chromatin immune complexes and they can receive cognate help from chromatin-specific 13C2 CD4+ T cells. We showed that activation of AM14 B cells by their cognate Ag PL2-3 induced glycolysis, and that the inhibition of glycolysis reduced their activation and differentiation into Ab-forming cells, in the absence or presence of T cell help. The dependency of autoreactive B cells on glycolysis is in sharp contrast with the previously reported dependency of 4-hydroxy-3-nitrophenyl acetyl-specific B cells on fatty acid oxidation. Contrary to AM14 B cells, the activation and differentiation of 13C2 T cells into follicular helper CD4+ T cells was not altered by 2DG, which differs from polyclonal CD4+ T cells from lupus-prone mice. These results further define the role of glycolysis in the production of lupus autoantibodies and demonstrate the need to evaluate the metabolic requirements of Ag-specific B and T cells.
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Affiliation(s)
- Georges Abboud
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Seung-Chul Choi
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Xiaojuan Zhang
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Yuk Pheel Park
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Nathalie Kanda
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Leilani Zeumer-Spataro
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Morgan Terrell
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Xiangyu Teng
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Kirsten Nündel
- Department of Medicine, Division of Rheumatology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Mark J. Shlomchik
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Laurence Morel
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, USA
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Elshikha AS, Teng XY, Kanda N, Li W, Choi SC, Abboud G, Terrell M, Fredenburg K, Morel L. TLR7 Activation Accelerates Cardiovascular Pathology in a Mouse Model of Lupus. Front Immunol 2022; 13:914468. [PMID: 35860280 PMCID: PMC9289616 DOI: 10.3389/fimmu.2022.914468] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/08/2022] [Indexed: 02/06/2023] Open
Abstract
We report a novel model of lupus-associated cardiovascular pathology accelerated by the TLR7 agonist R848 in lupus-prone B6.Sle1.Sle2.Sle3 (TC) mice. R848-treated TC mice but not non-autoimmune C57BL/6 (B6) controls developed microvascular inflammation and myocytolysis with intracellular vacuolization. This histopathology was similar to antibody-mediated rejection after heart transplant, although it did not involve complement. The TC or B6 recipients of serum or splenocytes from R848-treated TC mice developed a reactive cardiomyocyte hypertrophy, which also presents spontaneously in old TC mice as well as in TC.Rag-/- mice that lack B and T cells. Each of these cardiovascular lesions correspond to abnormalities that have been reported in lupus patients. Lymphoid and non-lymphoid immune cells as well as soluble factors contribute to lupus-associated cardiovascular lesions in TC mice, which can now be dissected using this model with and without R848 treatment.
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Affiliation(s)
- Ahmed S. Elshikha
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
- Department of Pharmaceutics, Zagazig University, Zagazig, Egypt
| | - Xiang Yu Teng
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Nathalie Kanda
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Wei Li
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Seung-Chul Choi
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Georges Abboud
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Morgan Terrell
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Kristianna Fredenburg
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
| | - Laurence Morel
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, United States
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Abstract
A high prevalence of metabolic syndrome (MetS) has been reported in multiple cohorts of systemic lupus erythematosus (SLE) patients, most likely as one of the consequences of autoimmune pathogenesis. Although MetS has been associated with inflammation, its consequences on the lupus immune system and on disease manifestations are largely unknown. The metabolism of immune cells is altered and overactivated in mouse models as well as in patients with SLE, and several metabolic inhibitors have shown therapeutic benefits. Here we review recent studies reporting these findings, as well as the effect of dietary interventions in clinical and preclinical studies of SLE. We also explore potential causal links between systemic and immunometabolism in the context of lupus, and the knowledge gap that needs to be addressed.
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Affiliation(s)
- Morgan Terrell
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Laurence Morel
- Correspondence: Dr. Laurence Morel, Department of Pathology, Immunology and Laboratory Medicine, University of Florida, 1600 SW Archer Rd, Gainesville, FL 32610-0275, USA.
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6
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Elshikha AS, Brown J, Kanda N, Ge Y, Teng X, Abboud G, Choi SC, Terrell M, Garrett TJ, Mohamadzadeh M, Morel L. The gut microbiota transfers the therapeutic effect of inhibiting glucose metabolism in lupus-prone mice. The Journal of Immunology 2022. [DOI: 10.4049/jimmunol.208.supp.174.02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease in which autoantibodies induce tissue damage including the kidney. Gut microbial dysbiosis contributes to SLE pathogenesis. An abnormal metabolism is a characteristic feature of SLE in which the inflammatory functions of CD4+ T cells rely on glycolysis. We have shown that treatment with 2-deoxy-D-glucose (2DG), a glycolysis inhibitor, reduced the expansion of germinal centers and eliminated the production of autoantibodies, ameliorating disease in lupus-prone mice, including (NZB × NZW)F1 and (NZW x BXSB)F1. Here we show that the 2DG treatment also maintained gut bacterial diversity, reduced the changes in bacterial populations that occurred as disease developed in these mice, and that it altered the distribution of fecal metabolites. We investigated the effect of fecal microbiota transplantation (FMT) from 2DG-treated or control mice into pre-autoimmune lupus-prone mice of the same strain. In both strains, FMT from 2DG-treated mice was highly protective, with a reduction or elimination of anti-dsDNA IgG production, immune cell activation, and renal pathology compared to FMT from control mice. Overall, our results demonstrated for the first time that the therapeutic effect of glucose inhibition in lupus is transferable through the gut microbiota. This implicates either a direct effect of glucose on pathogenic gut bacteria, or an indirect effect through the immune system normalized by glucose inhibition.
Supported b R01 AI143313
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Affiliation(s)
| | - Josephine Brown
- 1Department of Pathology, Immunology, and Laboratory Medicine, Univ. of Florida
| | - Nathalie Kanda
- 1Department of Pathology, Immunology, and Laboratory Medicine, Univ. of Florida
| | - Yong Ge
- 2Department of Infectious Diseases and Immunology, Univ. of Florida
| | - Xiangyu Teng
- 1Department of Pathology, Immunology, and Laboratory Medicine, Univ. of Florida
| | - Georges Abboud
- 1Department of Pathology, Immunology, and Laboratory Medicine, Univ. of Florida
| | - Seung-Chul Choi
- 1Department of Pathology, Immunology, and Laboratory Medicine, Univ. of Florida
| | - Morgan Terrell
- 1Department of Pathology, Immunology, and Laboratory Medicine, Univ. of Florida
| | - Timothy J Garrett
- 1Department of Pathology, Immunology, and Laboratory Medicine, Univ. of Florida
| | | | - Laurence Morel
- 1Department of Pathology, Immunology, and Laboratory Medicine, Univ. of Florida
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7
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Ma L, Brown J, Kanda N, Terrell M, Ge Y, Mohamadzadeh M, Morel L. A combination of genetic factors and dietary tryptophan shapes gut microbial dysbiosis in a lupus-prone mouse model. The Journal of Immunology 2022. [DOI: 10.4049/jimmunol.208.supp.174.03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
Gut microbial dysbiosis, impaired intestinal barrier and altered tryptophan metabolism have been reported in lupus patients. Dietary tryptophan modulated disease activity and modified the composition of microbiota in triple congenic (TC), B6.Sle1.Sle2.Sle3, lupus-prone mice. However, whether this modification is facilitated by tryptophan acting directly on the microbiota, or indirectly through lupus genetic susceptibility remains unknown. To address this question, we transplanted fecal samples from TC and B6 control mice into germ-free or antibiotic-treated B6 mice that were fed with high or low tryptophan. Tryptophan enriched different species of bacteria from transferred TC and B6 microbiota. A bloom of Ruminococcus gnavus, a bacterium associated with human lupus nephritis, only emerged in the recipients of TC microbiota fed with high tryptophan. Further, recipient mice showed distinct fecal metabolite profiles based on dietary tryptophan and the TC or B6 origin of the microbiota. Interestingly, both genetics and tryptophan impaired gut barrier integrity in recipient mice. These results suggest that the dysbiotic lupus microbiota is shaped by a combination of dietary tryptophan and genetic background, the latter most likely through autoimmune inflammation. In particular, the exclusive expansion of the pathobiont Ruminococcus gnavus by high tryptophan from the microbiota of lupus-prone mouse demonstrate that the interplay of genetic and environmental factors can influence the pathogenesis of lupus through modifying gut microbiota and gut permeability.
This work was supported by a grant from the NIH R01 AI43313 to Laurence Morel.
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Affiliation(s)
- Longhuan Ma
- 1Department of Pathology, Immunology, and Laboratory Medicine, University of Florida
| | - Josephine Brown
- 1Department of Pathology, Immunology, and Laboratory Medicine, University of Florida
| | - Nathalie Kanda
- 1Department of Pathology, Immunology, and Laboratory Medicine, University of Florida
| | - Morgan Terrell
- 1Department of Pathology, Immunology, and Laboratory Medicine, University of Florida
| | - Yong Ge
- 2Department of Infectious Diseases and Immunology, University of Florida
- 3Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, University of Florida
| | - Mansour Mohamadzadeh
- 2Department of Infectious Diseases and Immunology, University of Florida
- 3Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, University of Florida
| | - Laurence Morel
- 1Department of Pathology, Immunology, and Laboratory Medicine, University of Florida
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8
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Dennis M, Granger A, Ortiz A, Terrell M, Loukos M, Schober J. The anatomy of the musculocutaneous latissimus dorsi flap for neophalloplasty. Clin Anat 2017; 31:152-159. [PMID: 29178203 DOI: 10.1002/ca.23016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 11/22/2017] [Indexed: 12/22/2022]
Abstract
In transgender surgery, the ideal neophallus is one that: (a) is constructed using a reproducible procedure, (b) possesses tactile and erogenous sensation, (c) is large and rigid enough (naturally, or using a prosthesis) to permit penetrative intercourse, (d) leaves acceptable donor site morbidity, (e) results in esthetically satisfactory appearance, and (f) allows for voiding while standing. The musculocutaneous latissimus dorsi (MLD) flap has favorable results in the area of neophalloplasty. Among its advantages are acceptable donor site appearance, stiffness sufficient for intercourse, and esthetically satisfactory genital appearance. The anatomy of the MLD flap supports the creation of a neophallus for transsexual anatomy revision. Herein, we give an overview of the advantages and disadvantages of the procedure, and the anatomical details and surgical steps involved. Novel illustrations were created from standard surgical text descriptions to clarify this topic for surgical training and patient understanding and decision making. A review of the relevant literature regarding the anatomy, procedure development, and outcomes is presented. The MLD flap uses part of the latissimus dorsi muscle with branches of the thoracodorsal vessels and nerve to construct a neophallus. A thin strip of muscle around the pedicle is harvested, resulting in a slightly curvilinear scar. The blood supply is connected to the femoral artery and saphenous vein or the deep inferior epigastric artery and vein, while the nerve is connected to the ilioinguinal nerve or the obturator nerve. The MLD flap for neophalloplasty is a reliable graft with a well concealed scar and low donor site morbidity. Clin. Anat. 31:152-159, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- M Dennis
- Lake Erie College of Osteopathic Medicine, Erie, Pennsylvania
| | - A Granger
- School of Medicine, St. George's University, West Indies, Grenada.,Department of Neurology, NYU Langone Hospital - Brooklyn, Brooklyn, New York
| | - A Ortiz
- School of Medicine, St. George's University, West Indies, Grenada
| | - M Terrell
- Lake Erie College of Osteopathic Medicine, Erie, Pennsylvania
| | - M Loukos
- School of Medicine, St. George's University, West Indies, Grenada
| | - J Schober
- Pediatric Urology, University of Pittsburgh Medical Center - Hamot Hospital, Erie, Pennsylvania
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9
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Kim S, Dennis M, Holland J, Terrell M, Loukas M, Schober J. The anatomy of forearm free flap phalloplasty for transgender surgery. Clin Anat 2017; 31:145-151. [PMID: 29178477 DOI: 10.1002/ca.23014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 11/22/2017] [Indexed: 11/07/2022]
Affiliation(s)
- S Kim
- St. George's University, Grenada, West Indies
| | - M Dennis
- Lake Erie College of Osteopathic Medicine, Erie, Pennsylvania, 16509
| | - J Holland
- St. George's University, Grenada, West Indies
| | - M Terrell
- Lake Erie College of Osteopathic Medicine, Erie, Pennsylvania, 16509
| | - M Loukas
- St. George's University, Grenada, West Indies
| | - J Schober
- Pediatric Urology, University of Pittsburgh Hamot Medical Center, Erie, Pennsylvania, 16503
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10
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Zartler ER, Jenney FE, Terrell M, Eidsness MK, Adams MW, Prestegard JH. Structural basis for thermostability in aporubredoxins from Pyrococcus furiosus and Clostridium pasteurianum. Biochemistry 2001; 40:7279-90. [PMID: 11401576 DOI: 10.1021/bi0026831] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [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: 11/29/2022]
Abstract
The structures of apo- and holorubredoxins from Pyrococcus furiosus (PfRd) and Clostridium pasteurianum (CpRd) have been investigated and compared using residual dipolar couplings to probe the origin of thermostability. In the native, metal (Fe or Zn) containing form, both proteins can maintain native structure at very high temperatures (>70 degrees C) for extended periods of time. Significant changes in either structure or backbone dynamics between 25 and 70 degrees C are not apparent for either protein. A kinetic difference with respect to metal loss is observed as in previous studies, but the extreme stability of both proteins in the presence of metal makes thermodynamic differences difficult to monitor. In the absence of metal, however, a largely reversible thermal denaturation can be monitored, and a comparison of the two apoproteins can offer insights into the origin of stability. Below denaturation temperatures apo-PfRd is found to have a structure nearly identical to that of the native holo form, except immediately adjacent to the metal binding site. In contrast, apo-CpRd is found to have a structure distinctly different from that of its holo form at low temperatures. This structure is rapidly lost upon heating, unfolding at approximately 40 degrees C. A PfRd mutant with the hydrophobic core mutated to match that of CpRd shows no change in thermostability in the metal-free state. A metal-free chimera with residues 1-15 of CpRd and the remaining 38 residues of PfRd is severely destabilized and is unfolded at 25 degrees C. Hence, the hydrophobic core does not seem to be the key determinant of thermostability; instead, data point to the hydrogen bond network centered on the first 15 residues or the interaction of these 15 residues with other parts of the protein as a possible contributor to the thermostability.
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Affiliation(s)
- E R Zartler
- Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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11
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Seyer K, Newland C, Terrell M, Dalmotas D. The effect of mass, stiffness and geometry on injury outcome in side impacts - a parametric study. Stapp Car Crash J 2000; 44:1-11. [PMID: 17458714 DOI: 10.4271/2000-01-sc01] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This paper reports on a cooperative research project between the Australian Department of Transport and Regional Services and Transport Canada. This project was a parametric study aimed at better understanding the effects on side impact injury risk of: * Trolley mass * Barrier stiffness * Barrier stiffness distribution * Barrier face height above ground * Crabbed or perpendicular impact * Impact Speed The following observations on injury risk can be made from the tests: * The 2 largest effects for the driver are increasing the height of the barrier face (mainly thoracic) and test speed (all body regions). * Increasing the trolley mass, with a bullet / target mass ratio less than 1, has the effect of increasing only the pubic force. * Doubling the barrier stiffness increases injury risk in only the pelvic area. * The custom high and stiff element (attempting to replicate an SUV) increases both pelvic and abdominal loading.
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Affiliation(s)
- K Seyer
- Australian Department of Transport and Regional Services
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12
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Al-Hashimi HM, Valafar H, Terrell M, Zartler ER, Eidsness MK, Prestegard JH. Variation of molecular alignment as a means of resolving orientational ambiguities in protein structures from dipolar couplings. J Magn Reson 2000; 143:402-406. [PMID: 10729267 DOI: 10.1006/jmre.2000.2049] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Residual dipolar couplings for pairs of proximate magnetic nuclei in macromolecules can easily be measured using high-resolution NMR methods when the molecules are dissolved in dilute liquid crystalline media. The resulting couplings can in principle be used to constrain the relative orientation of molecular fragments in macromolecular systems to build a complete structure. However, determination of relative fragment orientations based on a single set of residual dipolar couplings is inherently hindered by the multi-valued nature of the angular dependence of the dipolar interaction. Even with unlimited dipolar data, this gives rise to a fourfold degeneracy in fragment orientations. In this Communication, we demonstrate a procedure based on an order tensor analysis that completely removes this degeneracy by combining residual dipolar coupling measurements from two alignment media. Application is demonstrated on (15)N-(1)H residual dipolar coupling data acquired on the protein zinc rubredoxin from Clostridium pasteurianum dissolved in two different bicelle media.
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Affiliation(s)
- H M Al-Hashimi
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, USA
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13
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Abstract
Visual acuity of amlyopic eyes, measured under binocular viewing conditions, was improved by reducing the contrast of targets presented to the normal eye. Improvement was also obtained by adjusting the temporal relationship between inputs to the normal and amblyopic eye. Optimal acuity was obtained by alternately presenting targets to the two eyes at rates centered about 2 and 7 Hz. These results are interpreted in terms of binocular contour interaction and metacontrast suppression. They suggest that a portion of the amblyope's acuity loss during binocular viewing conditions results from excessive masking by the dominant normal eye.
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