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Van Den Ham KM, Little MR, Bednarski OJ, Fusco EM, Mandal RK, Mitra R, Li S, Doumbo S, Doumtabe D, Kayentao K, Ongoiba A, Traore B, Crompton PD, Schmidt NW. Creation of a non-Western humanized gnotobiotic mouse model through the transplantation of rural African fecal microbiota. Microbiol Spectr 2023; 11:e0155423. [PMID: 37819130 PMCID: PMC10714993 DOI: 10.1128/spectrum.01554-23] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 09/05/2023] [Indexed: 10/13/2023] Open
Abstract
IMPORTANCE There is increasing evidence that microbes residing within the intestines (gut microbiota) play important roles in the well-being of humans. Yet, there are considerable challenges in determining the specific role of gut microbiota in human diseases owing to the complexity of diverse internal and environmental factors that can contribute to diseases. Mice devoid of all microorganisms (germ-free mice) can be colonized with human stool samples to examine the specific contribution of the gut microbiota to a disease. These approaches have been primarily focused on stool samples obtained from individuals in Western countries. Thus, there is limited understanding as to whether the same methods used to colonize germ-free mice with stool from Western individuals would apply to the colonization of germ-free mice with stool from non-Western individuals. Here, we report the results from colonizing germ-free mice with stool samples of Malian children.
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Affiliation(s)
- Kristin M. Van Den Ham
- Department of Pediatrics, Ryan White Center for Pediatric Infectious Diseases and Global Health, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Morgan R. Little
- Department of Pediatrics, Ryan White Center for Pediatric Infectious Diseases and Global Health, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Olivia J. Bednarski
- Department of Pediatrics, Ryan White Center for Pediatric Infectious Diseases and Global Health, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Elizabeth M. Fusco
- Department of Pediatrics, Ryan White Center for Pediatric Infectious Diseases and Global Health, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Rabindra K. Mandal
- Department of Pediatrics, Ryan White Center for Pediatric Infectious Diseases and Global Health, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Riten Mitra
- Department of Bioinformatics and Biostatistics, University of Louisville, Louisville, Kentucky, USA
| | - Shanping Li
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Safiatou Doumbo
- Mali International Center of Excellence in Research, Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Didier Doumtabe
- Mali International Center of Excellence in Research, Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Kassoum Kayentao
- Mali International Center of Excellence in Research, Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Aissata Ongoiba
- Mali International Center of Excellence in Research, Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Boubacar Traore
- Mali International Center of Excellence in Research, Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Peter D. Crompton
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Nathan W. Schmidt
- Department of Pediatrics, Ryan White Center for Pediatric Infectious Diseases and Global Health, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Logan BR, Fu D, Howard A, Fei M, Kou J, Little MR, Adom D, Mohamed FA, Blazar BR, Gafken PR, Paczesny S. Validated graft-specific biomarkers identify patients at risk for chronic graft-versus-host disease and death. J Clin Invest 2023; 133:e168575. [PMID: 37526081 PMCID: PMC10378149 DOI: 10.1172/jci168575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 06/16/2023] [Indexed: 08/02/2023] Open
Abstract
BACKGROUNDChronic graft-versus-host disease (cGVHD) is a serious complication of allogeneic hematopoietic cell transplantation (HCT). More accurate information regarding the risk of developing cGVHD is required. Bone marrow (BM) grafts contribute to lower cGVHD, which creates a dispute over whether risk biomarker scores should be used for peripheral blood (PB) and BM.METHODSDay 90 plasma proteomics from PB and BM recipients developing cGVHD revealed 5 risk markers that were added to 8 previous cGVHD markers to screen 982 HCT samples of 2 multicenter Blood and Marrow Transplant Clinical Trials Network (BMTCTN) cohorts. Each marker was tested for its association with cause-specific hazard ratios (HRs) of cGVHD using Cox-proportional-hazards models. We paired these clinical studies with biomarker measurements in a mouse model of cGVHD.RESULTSSpearman correlations between DKK3 and MMP3 were significant in both cohorts. In BMTCTN 0201 multivariate analyses, PB recipients with 1-log increase in CXCL9 and DKK3 were 1.3 times (95% CI: 1.1-1.4, P = 0.001) and 1.9 times (95%CI: 1.1-3.2, P = 0.019) and BM recipients with 1-log increase in CXCL10 and MMP3 were 1.3 times (95%CI: 1.0-1.6, P = 0.018 and P = 0.023) more likely to develop cGVHD. In BMTCTN 1202, PB patients with high CXCL9 and MMP3 were 1.1 times (95%CI: 1.0-1.2, P = 0.037) and 1.2 times (95%CI: 1.0-1.3, P = 0.009) more likely to develop cGVHD. PB patients with high biomarkers had increased likelihood to develop cGVHD in both cohorts (22%-32% versus 8%-12%, P = 0.002 and P < 0.001, respectively). Mice showed elevated circulating biomarkers before the signs of cGVHD.CONCLUSIONBiomarker levels at 3 months after HCT identify patients at risk for cGVHD occurrence.FUNDINGNIH grants R01CA168814, R21HL139934, P01CA158505, T32AI007313, and R01CA264921.
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Affiliation(s)
- Brent R. Logan
- Division of Biostatistics and Center for International Blood and Marrow Transplant Research, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Denggang Fu
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Alan Howard
- Be The Match and Center for International Blood and Marrow Transplant Research, Minneapolis, Minnesota, USA
| | - Mingwei Fei
- Be The Match and Center for International Blood and Marrow Transplant Research, Minneapolis, Minnesota, USA
| | - Jianqun Kou
- Division of Biostatistics and Center for International Blood and Marrow Transplant Research, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Morgan R. Little
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Djamilatou Adom
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Fathima A. Mohamed
- Department of Pediatrics, Division of Blood & Marrow Transplant & Cellular Therapy, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Bruce R. Blazar
- Department of Pediatrics, Division of Blood & Marrow Transplant & Cellular Therapy, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Philip R. Gafken
- Proteomics & Metabolomics shared resource, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Sophie Paczesny
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, USA
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Perez-Leighton C, Little MR, Grace M, Billington C, Kotz CM. Orexin signaling in rostral lateral hypothalamus and nucleus accumbens shell in the control of spontaneous physical activity in high- and low-activity rats. Am J Physiol Regul Integr Comp Physiol 2016; 312:R338-R346. [PMID: 28039192 DOI: 10.1152/ajpregu.00339.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 12/21/2016] [Accepted: 12/21/2016] [Indexed: 01/04/2023]
Abstract
Spontaneous physical activity (SPA) describes activity outside of formal exercise and shows large interindividual variability. The hypothalamic orexin/hypocretin peptides are key regulators of SPA. Orexins drive SPA within multiple brain sites, including rostral lateral hypothalamus (LH) and nucleus accumbens shell (NAcSh). Rats with high basal SPA (high activity, HA) show higher orexin mRNA expression and SPA after injection of orexin-A in rostral LH compared with low-activity (LA) rats. Here, we explored the contribution of orexin signaling in rostral LH and NAcSh to the HA/LA phenotype. We found that HA rats have higher sensitivity to SPA after injection of orexin-A in rostral LH, but not in NAcSh. HA and LA rats showed similar levels of orexin receptor expression in rostral LH, and activation of orexin-producing neurons after orexin-A injection in rostral LH. Also, in HA and LA rats, the coinjection of orexin-A in rostral LH and NAcSh failed to further increase SPA beyond the effects of orexin-A in rostral LH. Pretreatment with muscimol, a GABAA receptor agonist, in NAcSh potentiated SPA produced by orexin-A injection in rostral LH in HA but not in LA rats. Our results suggest that a feedback loop from orexin-responsive neurons in rostral LH to orexin neurons and a the NAcSh-orexin neuron-rostral LH circuit regulate SPA. Overall, our data suggest that differences in orexin sensitivity in rostral LH and its modulation by GABA afferents from NAcSh contribute to individual SPA differences.
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Affiliation(s)
- Claudio Perez-Leighton
- Center for Integrative Medicine and Innovative Science, Facultad de Medicina, Universidad Andres Bello, Santiago, Region Metropolitana, Chile.,Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota; and
| | - Morgan R Little
- Geriatric Research Education and Clinical Center, Minneapolis Veterans Affairs Health Care System, Minneapolis, Minnesota.,Minnesota Obesity Center, University of Minnesota, Minnesota
| | - Martha Grace
- Geriatric Research Education and Clinical Center, Minneapolis Veterans Affairs Health Care System, Minneapolis, Minnesota
| | - Charles Billington
- Geriatric Research Education and Clinical Center, Minneapolis Veterans Affairs Health Care System, Minneapolis, Minnesota.,Minnesota Obesity Center, University of Minnesota, Minnesota.,Department of Medicine, University of Minnesota, Minneapolis, St. Paul, Minnesota
| | - Catherine M Kotz
- Geriatric Research Education and Clinical Center, Minneapolis Veterans Affairs Health Care System, Minneapolis, Minnesota; .,Minnesota Obesity Center, University of Minnesota, Minnesota.,Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota
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Noble EE, Mavanji V, Little MR, Billington CJ, Kotz CM, Wang C. Exercise reduces diet-induced cognitive decline and increases hippocampal brain-derived neurotrophic factor in CA3 neurons. Neurobiol Learn Mem 2014; 114:40-50. [PMID: 24755094 PMCID: PMC4143428 DOI: 10.1016/j.nlm.2014.04.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 04/01/2014] [Accepted: 04/07/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Previous studies have shown that a western diet impairs, whereas physical exercise enhances hippocampus-dependent learning and memory. Both diet and exercise influence expression of hippocampal brain-derived neurotrophic factor (BDNF), which is associated with improved cognition. We hypothesized that exercise reverses diet-induced cognitive decline while increasing hippocampal BDNF. METHODS To test the effects of exercise on hippocampal-dependent memory, we compared cognitive scores of Sprague-Dawley rats exercised by voluntary running wheel (RW) access or forced treadmill (TM) to sedentary (Sed) animals. Memory was tested by two-way active avoidance test (TWAA), in which animals are exposed to a brief shock in a specific chamber area. When an animal avoids, escapes or has reduced latency to do either, this is considered a measure of memory. In a second experiment, rats were fed either a high-fat diet or control diet for 16 weeks, then randomly assigned to running wheel access or sedentary condition, and TWAA memory was tested once a week for 7 weeks of exercise intervention. RESULTS Both groups of exercised animals had improved memory as indicated by reduced latency to avoid and escape shock, and increased avoid and escape episodes (p<0.05). Exposure to a high-fat diet resulted in poor performance during both the acquisition and retrieval phases of the memory test as compared to controls. Exercise reversed high-fat diet-induced memory impairment, and increased brain-derived neurotrophic factor (BDNF) in neurons of the hippocampal CA3 region. CONCLUSIONS These data suggest that exercise improves memory retrieval, particularly with respect to avoiding aversive stimuli, and may be beneficial in protecting against diet induced cognitive decline, likely via elevated BDNF in neurons of the CA3 region.
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Affiliation(s)
- Emily E Noble
- Minnesota Obesity Center, 1334 Eckles Avenue, Saint Paul, MN 55108, USA; Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, Saint Paul, MN 55108, USA
| | - Vijayakumar Mavanji
- Veterans Affairs Medical Center, One Veterans Drive, Research Route 151, Minneapolis, MN 55417, USA; Minnesota Obesity Center, 1334 Eckles Avenue, Saint Paul, MN 55108, USA
| | - Morgan R Little
- Minnesota Obesity Center, 1334 Eckles Avenue, Saint Paul, MN 55108, USA; Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, Saint Paul, MN 55108, USA
| | - Charles J Billington
- Veterans Affairs Medical Center, One Veterans Drive, Research Route 151, Minneapolis, MN 55417, USA; Minnesota Obesity Center, 1334 Eckles Avenue, Saint Paul, MN 55108, USA; Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, Saint Paul, MN 55108, USA; Department of Medicine, University of Minnesota, Minneapolis, MN 554553, USA
| | - Catherine M Kotz
- Veterans Affairs Medical Center, One Veterans Drive, Research Route 151, Minneapolis, MN 55417, USA; Minnesota Obesity Center, 1334 Eckles Avenue, Saint Paul, MN 55108, USA; Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, Saint Paul, MN 55108, USA; Graduate Program in Neuroscience, University of Minnesota, 321 Church Street SE, Minneapolis, MN 55455, USA
| | - ChuanFeng Wang
- Veterans Affairs Medical Center, One Veterans Drive, Research Route 151, Minneapolis, MN 55417, USA; Minnesota Obesity Center, 1334 Eckles Avenue, Saint Paul, MN 55108, USA; Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, Saint Paul, MN 55108, USA.
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Grothe HL, Little MR, Sjogren PP, Chang AA, Nelson EF, Yuan C. Altered protein conformation and lower stability of the dystrophic transforming growth factor beta-induced protein mutants. Mol Vis 2013; 19:593-603. [PMID: 23559853 PMCID: PMC3611947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 03/18/2013] [Indexed: 12/02/2022] Open
Abstract
PURPOSE Transforming growth factor beta-induced protein (TGFBIp) is a widely expressed extracellular matrix protein that plays roles in cell adhesion and migration, differentiation, apoptosis, bone morphogenesis, and carcinogenesis. Mutations of TGFBIp have been linked to stromal corneal dystrophies, a group of protein conformational diseases characterized by abnormal protein aggregations in the cornea. However, the underlying pathogenic mechanism remains elusive due to a lack of insight into the molecular properties of the disease-causing mutants. In the current study, we applied spectroscopic tools to compare the conformation and protein stability of recombinant wild-type (WT) TGFBIp to two dystrophic mutants, R124C and R555W. METHODS A serum-free expression system was used to produce the recombinant TGFBIp proteins. Fluorescence and far-ultraviolet circular dichroism spectroscopies were used to compare WT and dystrophic mutants under various conditions. RESULTS Our results showed that dystrophic mutants were processed differentially by the expressing cells and produced different proteolytic fragment patterns by proteolysis. Intrinsic tryptophan fluorescence studies revealed moderate shifts in the emission maxima and increased quenching by iodide ion of mutant TGFBIp, suggesting a different conformation than WT protein. Denaturation experiments indicated a difference in protein stability between WT and mutant proteins. Under oxidizing conditions, the mutants produced higher 1-anilinonaphthalene-8-sulfonic acid and thioflavin T fluorescence signals than the WT, indicating increased protein unfolding and fibril formation, respectively. Finally, far-ultraviolet circular dichroism spectroscopy revealed that WT TGFBIp undergoes concentration-dependent conformational changes; similar experiments were not possible on mutant TGFBIp, which remained soluble only at low concentrations. CONCLUSIONS Our study provides new evidence for the pathogenic mechanism of dystrophic mutants. Although mutant TGFBIp has moderate but consistent structural perturbations, other factors such as oxidation or degradation may be required to cause the phenotypic abnormal aggregations.
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Grothe HL, Little MR, Cho AS, Huang AJ, Yuan C. Denaturation and solvent effect on the conformation and fibril formation of TGFBIp. Mol Vis 2009; 15:2617-26. [PMID: 20011632 PMCID: PMC2790481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Accepted: 11/30/2009] [Indexed: 11/17/2022] Open
Abstract
PURPOSE Transforming growth factor beta-induced protein (TGFBIp) aggregates into the phenotypic amyloid fibrils and/or non-amyloid deposits in corneal dystrophies and other disorders. While significant progress has been made in molecular genetics to successfully establish the link between the missense mutations of TGFBI and TGFBIp-related corneal dystrophies, the underlying mechanism for the abnormal aggregation remains elusive due to the lack of insights into the conformational perturbations induced by mutations. In the present study, we examined the effects of denaturants and a co-solvent on recombinant TGFBIp, with a focus on protein conformational changes and amyloid fibril formation. METHODS Recombinant TGFBIp was subjected to various spectroscopic studies, such as far-ultraviolet circular dichroism (far-UV CD), intrinsic tryptophan fluorescence and quenching, and 1-anilinonaphthalene-8-sulfonic acid (ANS) fluorescence, under various denaturing conditions (urea and guanidine hydrochloride [GndHCl], acidic pH, and trifluoroethanol [TFE, co-solvent]). A thioflavin T (ThT) fluorescence assay was used to determine the fibril formation of TGFBIp. In addition, a rabbit polyclonal antibody against the oligomer precursors that initiate the formation of amyloid fibrils was also used in dot blot experiments to detect the formation of prefibrillar precursors. RESULTS The purified recombinant TGFBIp is in the folded state according to its intrinsic tryptophan fluorescence analyses. A single-step unfolding process was observed in the GndHCl denaturation experiment. Results from far-UV CD, intrinsic tryptophan fluorescence, and ANS fluorescence experiments showed that TFE exerted its solvent effects by initially unfolding and transforming TGFBIp to a beta-sheet-enriched conformer at 20%. When increased to 40%, TFE changed TGFBIp into a non-native alpha-helix conformer. Although GndHCl and TFE led to protein unfolding, enhanced fibril formation could only be observed in the presence of TFE and at acidic pH, according to the ThT fluorescence assays. The paradigmatic protofibrillar TGFBIp oligomers were also detected during the fibril formation by the dot blot experiment. CONCLUSIONS Our results suggest that protein unfolding may serve as the prerequisite but is not sufficient for the fibrillogenesis. Other factors, such as the solvent used, fragmentation, or pH, may also be crucial for the formation of TGFBIp fibrils.
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Affiliation(s)
- Heather L. Grothe
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN
| | - Morgan R. Little
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN
| | - Angela S. Cho
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN
| | - Andrew J.W. Huang
- Department of Ophthalmology and Visual Sciences, Washington University, St. Louis, MO
| | - Ching Yuan
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN
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Armien AG, Hu S, Little MR, Robinson N, Lokensgard JR, Low WC, Cheeran MCJ. Chronic cortical and subcortical pathology with associated neurological deficits ensuing experimental herpes encephalitis. Brain Pathol 2009; 20:738-50. [PMID: 20002440 DOI: 10.1111/j.1750-3639.2009.00354.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Long-term neurological sequela is common among herpes simplex encephalitis (HSE) survivors. Animal models for HSE are used to investigate mechanisms of acute disease, but little has been done to model chronic manifestations of HSE. The current study presents a detailed, systematic analysis of chronic neuropathology, including characterization of topography and sequential progression of degenerative lesions and inflammation. Subsequent to intranasal HSV-1 infection, inflammatory responses that were temporally and spatially distinct persisted in infected cortical and brain stem regions. Neutrophils were present exclusively within the olfactory bulb and brain stem regions during the acute phase of infection, while the chronic inflammation was marked by plasma cells, lymphocytes and activated microglia. The chronic lymphocytic infiltrate, cytokine production, and activated microglia were associated with the loss of cortical neuropile in the entorhinal cortex and hippocampus. Animals surviving the acute infection showed a spectrum of chronic lesions from decreased brain volume, neuronal loss, activated astrocytes, and glial scar formation to severe atrophy and cavitations of the cortex. These lesions were also associated with severe spatial memory deficits in surviving animals. Taken together, this model can be utilized to further investigate the mechanisms of neurological defects that follow in the wake of HSE.
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Affiliation(s)
- Anibal G Armien
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, MN, USA
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Ropp PA, Little MR, Cheng PW. Mucin biosynthesis: purification and characterization of a mucin beta 6N-acetylglucosaminyltransferase. J Biol Chem 1991; 266:23863-71. [PMID: 1836212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We have purified, to apparent homogeneity, a mucin beta 6N-acetylglucosaminyltransferase (beta 6GlcNAc transferase) from bovine tracheal epithelium. Golgi membranes were isolated from a 0.25 M sucrose homogenate of epithelial scrapings by discontinuous sucrose gradient centrifugation. The Golgi membranes were solubilized with 1% Triton X-100 in the presence of 1 mM Gal beta 1-3GalNAc alpha benzyl (Bzl) to stabilize the beta 6GlcNAc transferase. The solubilized enzyme was bound to a UDP-hexanolamine-Actigel-ALD Superflow affinity column equilibrated with 1 mM Gal beta 1-3GalNAc alpha Bzl and 5 mM Mn2+. Elution of the enzyme with 0.5 mM UDP-GlcNAc resulted in a 133,800-fold purification with a 1.3% yield and a specific activity of 70 mumol/min/mg protein. Radioiodination of the purified enzyme followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography revealed a single band at 69,000 Da. Kinetic analyses of the beta 6GlcNAc transferase-catalyzed reaction showed an ordered sequential mechanism in which UDP-GlcNAc binds to the enzyme first and UDP is released last. The Km values for UDP-GlcNAc and Gal beta 1-3GalNAc alpha Bzl were 0.36 and 0.14 mM, respectively. Acceptor competition studies showed that the purified beta 6GlcNAc transferase can use core 1 and core 3 mucin oligosaccharides as well as GlcNAc beta 1-3Gal beta R as acceptor substrates. Proton NMR analyses of the three products demonstrated that GlcNAc was added in a beta 1-6 linkage to the penultimate GalNAc or Gal, suggesting that this enzyme is capable of synthesizing all beta 6GlcNAc structures found in mucin-type oligosaccharides.
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Affiliation(s)
- P A Ropp
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599
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Abstract
Twenty young (45 years or younger) and 20 older (55 years or older) adult patients with mild hypertension were enrolled in this study to compare the hemodynamic effects of labetalol versus placebo in two age groups. Ten patients in each group were randomly assigned to receive either a single oral dose of labetalol (200 mg) or placebo. Hemodynamic parameters were recorded immediately before and two hours after ingestion. Labetalol was more effective than placebo in significantly lowering systolic blood pressure (-11 versus + 5 mm Hg, -23 versus + 4 mm Hg), diastolic blood pressure (-9 versus + 2 mm Hg, -12 versus + 5 mm Hg), and total systemic resistance (-259 versus + 42 dynes-sec cm-5, -390 versus + 74 dynes-sec cm-5) in young and older hypertensive subjects, respectively. There was no significant changes in heart rate, stroke volume index, or cardiac index in either age group. These data indicate that labetalol lowers blood pressure in young an older hypertensives primarily by reducing peripheral resistance and that the antihypertensive effect may be somewhat greater in older patients.
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Affiliation(s)
- J C Buell
- Division of Cardiology, Texas Tech University Health Sciences Center, Lubbock 79430
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Abstract
This paper has reviewed the number of chromatographic methods by which one may determine the absolute configuration of sugars. Both indirect methods (converting the enantiomeric pair into diastereomers) and direct methods (using chiral stationary phases) have been discussed. Resolving reagents for the indirect methods include chiral hydroxy compounds, chiral amines, and chiral thiols; with subsequent separation of the diastereomers either by gas-liquid chromatography or by high pressure liquid chromatography. Direct methods discussed have exclusively utilized chiral substitution of organopolysiloxane phases for the separation of enantiomeric sugars as volatile derivatives by gas-liquid chromatography.
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Cheng PW, Wingert WE, Little MR, Wei R. Mucin biosynthesis. Properties of a bovine tracheal mucin beta-6-N-acetylglucosaminyltransferase. Biochem J 1985; 227:405-12. [PMID: 3924025 PMCID: PMC1144859 DOI: 10.1042/bj2270405] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We have characterized a bovine tracheal mucin beta-6-N-acetylglucosaminyltransferase that catalyses the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to the C-6 of the N-acetylgalactosamine residue of galactosyl-beta 1----3-N-acetylgalactosamine. Optimal enzyme activity was obtained between pH 7.5-8.5, at 5mM-MnCl2, and at 0.06-0.08% (v/v) Triton X-100 (or Nonidet P-40), or 0.5-5.0% (v/v) Tween 20. Ba2+, Mg2+ and Ca2+ could partially replace Mn2+, but Co2+, Fe2+, Cd2+ and Zn2+ could not. Sodium dodecyl sulphate, cetylpyridinium chloride, sodium deoxycholate, octyl beta-D-glucoside, digitonin and alkyl alcohols were less effective in enhancing enzyme activity, and dimethyl sulphoxide was ineffective. The apparent Michaelis constants were 1.25 mM for UDP-N-acetylglucosamine, 0.94-3.34 mM for freezing-point-depressing glycoprotein and 0.19 mM for periodate-treated blood-group-A porcine submaxillary mucin. Asialo ovine submaxillary mucin could not serve as the glycosyl acceptor. The structure of the 14C-labelled oligosaccharide obtained by alkaline-borohydride treatment of the product was identified as Gal beta 1----3(Glc-NAc beta 1----6)N-acetylgalactosaminitol by beta-hexosaminidase treatment, gas chromatography-mass spectrometry and 1H-n.m.r. (270 MHz) analysis. The enzyme is important in the regulation of mucin oligosaccharide biosynthesis.
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