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Wahlström H, Lindberg A, Lindh J, Wallensten A, Lindqvist R, Plym-Forshell L, Osterman Lind E, Ågren EO, Widgren S, Carlsson U, Christensson D, Cedersmyg M, Lindström E, Olsson GE, Hörnfeldt B, Barragan A, Davelid C, Hjertqvist M, Elvander M. Investigations and actions taken during 2011 due to the first finding of Echinococcus multilocularis in Sweden. Euro Surveill 2012; 17. [DOI: 10.2807/ese.17.28.20215-en] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Echinococcus multilocularis is a parasite that can cause alveolar echinococcosis disease. After the first positive finding of E. multilocularis in Sweden in 2011, a consulting group with representatives from relevant authorities was summoned. In this group, all relevant information was shared, strategies for information dissemination and any actions to be taken due to the finding of E. multilocularis were discussed and decided. The present paper describes the actions taken during 2011 and the results thereof, including surveillance in animals, risk assessment for humans to become infected and recommendations given to the public. Further discussion about whether the parasite was introduced, and if so, how, as well as possible future development of the infection in animals and humans in Sweden and future actions are included.
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Affiliation(s)
- H Wahlström
- National Veterinary Institute, Uppsala, Sweden
| | - A Lindberg
- National Veterinary Institute, Uppsala, Sweden
| | - J Lindh
- Swedish Institute for Communicable Disease Control, Solna, Sweden
| | - A Wallensten
- Swedish Institute for Communicable Disease Control, Solna, Sweden
| | | | | | | | - E O Ågren
- National Veterinary Institute, Uppsala, Sweden
| | - S Widgren
- National Veterinary Institute, Uppsala, Sweden
| | - U Carlsson
- National Veterinary Institute, Uppsala, Sweden
| | | | - M Cedersmyg
- Swedish Board of Agriculture, Jönköping, Sweden
| | | | - G E Olsson
- Swedish University of Agricultural Sciences, Umeå, Sweden
| | - B Hörnfeldt
- Swedish University of Agricultural Sciences, Umeå, Sweden
| | - A Barragan
- Swedish Institute for Communicable Disease Control, Solna, Sweden
| | - C Davelid
- National Board of Health and Welfare, Stockholm, Sweden
| | - M Hjertqvist
- Swedish Institute for Communicable Disease Control, Solna, Sweden
| | - M Elvander
- National Veterinary Institute, Uppsala, Sweden
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2
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Abstract
Development and implementation of global animal disease surveillance has been limited by the lack of information systems that enable near real-time data capturing, sharing, analysis, and related decision- and policy-making. The objective of this paper is to describe requirements for global animal disease surveillance, including design and functionality of tools and methods for visualization and analysis of animal disease data. The paper also explores the potential application of techniques for spatial and spatio-temporal analysis on global animal disease surveillance, including for example, landscape genetics, social network analysis, and Bayesian modeling. Finally, highly pathogenic avian influenza data from Denmark and Sweden are used to illustrate the potential application of a novel system (Disease BioPortal) for data sharing, visualization, and analysis for regional and global surveillance efforts.
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Affiliation(s)
- A Perez
- Center for Animal Disease Modeling and Surveillance, School of Veterinary Medicine, University of California, Davis, USA.
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3
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Carlsson U, Wallgren P, Renström LHM, Lindberg A, Eriksson H, Thorén P, Eliasson-Selling L, Lundeheim N, Nörregard E, Thörn C, Elvander M. Emergence of Porcine Reproductive and Respiratory Syndrome in Sweden: Detection, Response and Eradication. Transbound Emerg Dis 2009; 56:121-31. [DOI: 10.1111/j.1865-1682.2008.01065.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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4
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Svantesson U, Carlsson U, Grimby G. Isokinetic measurements of calf muscle stiffness following fatiguing exertion. ISOKINET EXERC SCI 2004. [DOI: 10.3233/ies-2004-0180] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- U. Svantesson
- Rehabilitation Medicine, Göteborg University, Sweden
| | - U. Carlsson
- Rehabilitation Medicine, Göteborg University, Sweden
| | - G. Grimby
- Rehabilitation Medicine, Göteborg University, Sweden
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5
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Carlsson U, Henning GB, Svantesson U, Sunnerhagen K. Plantar flexor muscle action while sitting, standing and prone in patients with upper motor neuron lesion due to stroke. ISOKINET EXERC SCI 2003. [DOI: 10.3233/ies-2003-0148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- U. Carlsson
- Institute of Clinical Neuroscience – Rehabilitation Medicine, Göteborg, Sweden
| | - G.-B. Henning
- Institute of Clinical Neuroscience – Rehabilitation Medicine, Göteborg, Sweden
| | - U. Svantesson
- Institute of Occupational Therapy and Physical Therapy, Göteborg, Sweden
- Department of Orthopedic Surgery, Göteborg University, Göteborg, Sweden
| | - K.S. Sunnerhagen
- Institute of Clinical Neuroscience – Rehabilitation Medicine, Göteborg, Sweden
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6
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Gånheim C, Hultén C, Carlsson U, Kindahl H, Niskanen R, Waller KP. The acute phase response in calves experimentally infected with bovine viral diarrhoea virus and/or Mannheimia haemolytica. J Vet Med B Infect Dis Vet Public Health 2003; 50:183-90. [PMID: 12916692 DOI: 10.1046/j.1439-0450.2003.00658.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of this investigation was to study differences and similarities in the acute phase response of calves experimentally infected in the respiratory tract with either bovine viral diarrhoea virus (BVDV) or Mannheima haemolytica (Mh), or with a combination of both (BVDV/Mh). A non-inoculated control group was also included. The acute phase response was measured by serum or plasma concentrations of the acute phase proteins (APPs) haptoglobin, serum amyloid A (SAA) and fibrinogen, and of cortisol, prostaglandin F2alpha-metabolite and interferon-alpha (IFN-alpha) activity. Clinical symptoms were also recorded and were most severe in the BVDV/Mh group. The symptoms were mild to moderate in the BVDV group, while none, or very mild symptoms were observed in the Mh group. In all inoculated groups, a significant acute phase response was observed, with elevated values of haptoglobin, SAA and fibrinogen, while the control group remained unaffected throughout the study. In general, the magnitude of the response was similar, but the duration of elevated concentrations of APPs was significantly longer in the BVDV/Mh group than in the BVDV group, reflecting the duration of the clinical symptoms. However, in the single infection groups, the APP response and the clinical symptoms were not correlated. The IFN-alpha activity increased in all BVDV-inoculated animals, but no response in cortisol and PGF2alpha-metabolite concentrations was observed after infection. Basal levels of serum concentrations of haptoglobin, SAA and fibrinogen were established and may be used for evaluating calf health in herds. The duration of elevated haptoglobin, SAA and fibrinogen values did not differ significantly within groups indicating that their value as indicator of disease is equal.
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Affiliation(s)
- C Gånheim
- Department of Obstetrics and Gynaecology, Centre for Reproductive Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
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7
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Huber M, Lindgren M, Hammarström P, Mårtensson LG, Carlsson U, Eaton GR, Eaton SS. Phase memory relaxation times of spin labels in human carbonic anhydrase II: pulsed EPR to determine spin label location. Biophys Chem 2001; 94:245-56. [PMID: 11804734 DOI: 10.1016/s0301-4622(01)00239-3] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Phase memory relaxation times (T(M) or T(2)) of spin labels in human carbonic anhydrase II (HCA II) are reported. Spin labels (N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl)iodoacetamide, IPSL) were introduced at cysteines, by site-directed mutagenesis at seven different positions in the protein. By two pulse electron paramagnetic resonance (EPR), electron spin echo decays at 45 K are measured and fitted by stretched exponentials, resulting in relaxation parameters T(M) and x. T(M) values of seven positions are between 1.6 micros for the most buried residue (L79C) and 4.7 micros for a residue at the protein surface (W245C). In deuteriated buffer, longer T(M) are found for all but the most buried residues (L79C and W97C), and electron spin echo envelop modulation (ESEEM) of deuterium nuclei is observed. Different deuterium ESEEM patterns for W95C and W16C (surface residue) indicate differences in the local water concentration, or accessibility, of the spin label by deuterium. We propose T(M) as a parameter to determine the spin label location in proteins. Furthermore, these systems are interesting for studying the pertaining relaxation mechanism.
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Affiliation(s)
- M Huber
- Department of Molecular Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands.
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8
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Owenius R, Osterlund M, Svensson M, Lindgren M, Persson E, Freskgård PO, Carlsson U. Spin and fluorescent probing of the binding interface between tissue factor and factor VIIa at multiple sites. Biophys J 2001; 81:2357-69. [PMID: 11566805 PMCID: PMC1301706 DOI: 10.1016/s0006-3495(01)75882-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The specific complex between the extracellular part of tissue factor (sTF) and factor VIIa (FVIIa) was chosen as a model for studies of the binding interface between two interacting proteins. Six surface-exposed positions in sTF, residues known to contribute to the sTF-FVIIa interaction, were selected for cysteine mutation and site-directed labeling with spin and fluorescent probes. The binding interface was characterized by spectral data from electron paramagnetic resonance (EPR) and steady-state and time-domain fluorescence spectroscopy. The labels reported on compact local environments at positions 158 and 207 in the interface region between sTF and the gamma-carboxyglutamic acid (Gla) domain of FVIIa, and at positions 22 and 140 in the interface region between sTF and the first epidermal growth factor-like (EGF1) domain of FVIIa. The tightness of the local interactions in these parts of the interface is similar to that seen in the interior of globular proteins. This was further emphasized by the reduced local polarity detected by the fluorescent label upon FVIIa binding, especially in the sTF-Gla region. There were indications of structural rigidity also at positions 45 and 94 in the interface region between sTF and the protease domain (PD) of FVIIa, despite the perturbed cofactor function of these sTF variants. The results of the present study indicate that the multi-probing approach enables comparison of the tightness and characteristics of interaction along the binding interface of a protein complex. This approach also increases the probability of acquiring reliable structural data that are descriptive of the wild-type proteins.
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Affiliation(s)
- R Owenius
- IFM-Department of Chemical Physics, Linköping University, SE-581 83 Linköping, Sweden
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9
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Svedhem S, Enander K, Karlsson M, Sjöbom H, Liedberg B, Löfås S, Mårtensson LG, Sjöstrand SE, Svensson S, Carlsson U, Lundström I. Subtle differences in dissociation rates of interactions between destabilized human carbonic anhydrase II mutants and immobilized benzenesulfonamide inhibitors probed by a surface plasmon resonance biosensor. Anal Biochem 2001; 296:188-96. [PMID: 11554714 DOI: 10.1006/abio.2001.5301] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [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: 11/22/2022]
Abstract
The development of commercial biosensors based on surface plasmon resonance has made possible careful characterization of biomolecular interactions. Here, a set of destabilized human carbonic anhydrase II (HCA II) mutants was investigated with respect to their interaction kinetics with two different immobilized benzenesulfonamide inhibitors. Point mutations were located distantly from the active site, and the destabilization energies were up to 23 kJ/mol. The dissociation rate of wild-type HCA II, as determined from the binding to the inhibitor with higher affinity, was 0.019 s(-1). For the mutants, dissociation rates were faster (0.022-0.025 s(-1)), and a correlation between faster dissociation and a high degree of destabilization was observed. We interpreted these results in terms of increased dynamics of the tertiary structures of the mutants. This interpretation was supported by entropy determinations, showing that the entropy of the native structure significantly increased upon destabilization of the protein molecule. Our findings demonstrate the applicability of modern biosensor technology in the study of subtle details in molecular interaction mechanisms, such as the long-range effect of point mutations on interaction kinetics.
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Affiliation(s)
- S Svedhem
- Division of Chemistry, Linköpings Universitet, Linköping, S-581 83, Sweden
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10
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Persson M, Harbridge JR, Hammarström P, Mitri R, Mårtensson LG, Carlsson U, Eaton GR, Eaton SS. Comparison of electron paramagnetic resonance methods to determine distances between spin labels on human carbonic anhydrase II. Biophys J 2001; 80:2886-97. [PMID: 11371461 PMCID: PMC1301472 DOI: 10.1016/s0006-3495(01)76254-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Four doubly spin-labeled variants of human carbonic anhydrase II and corresponding singly labeled variants were prepared by site-directed spin labeling. The distances between the spin labels were obtained from continuous-wave electron paramagnetic resonance spectra by analysis of the relative intensity of the half-field transition, Fourier deconvolution of line-shape broadening, and computer simulation of line-shape changes. Distances also were determined by four-pulse double electron-electron resonance. For each variant, at least two methods were applicable and reasonable agreement between methods was obtained. Distances ranged from 7 to 24 A. The doubly spin-labeled samples contained some singly labeled protein due to incomplete labeling. The sensitivity of each of the distance determination methods to the non-interacting component was compared.
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Affiliation(s)
- M Persson
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA
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11
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Hammarström P, Owenius R, Mårtensson LG, Carlsson U, Lindgren M. High-resolution probing of local conformational changes in proteins by the use of multiple labeling: unfolding and self-assembly of human carbonic anhydrase II monitored by spin, fluorescent, and chemical reactivity probes. Biophys J 2001; 80:2867-85. [PMID: 11371460 PMCID: PMC1301471 DOI: 10.1016/s0006-3495(01)76253-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [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: 11/22/2022] Open
Abstract
Two different spin labels, N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl)iodoacetamide (IPSL) and (1-oxyl-2,2,5,5-tetramethylpyrroline-3-methyl) methanethiosulfonate (MTSSL), and two different fluorescent labels 5-((((2-iodoacetyl)amino)-ethyl)amino)naphtalene-1-sulfonic acid (IAEDANS) and 6-bromoacetyl-2-dimetylaminonaphtalene (BADAN), were attached to the introduced C79 in human carbonic anhydrase (HCA II) to probe local structural changes upon unfolding and aggregation. HCA II unfolds in a multi-step manner with an intermediate state populated between the native and unfolded states. The spin label IPSL and the fluorescent label IAEDANS reported on a substantial change in mobility and polarity at both unfolding transitions at a distance of 7.4-11.2 A from the backbone of position 79. The shorter and less flexible labels BADAN and MTSSL revealed less pronounced spectroscopic changes in the native-to-intermediate transition, 6.6-9.0 A from the backbone. At intermediate guanidine (Gu)-HCl concentrations the occurrence of soluble but irreversibly aggregated oligomeric protein was identified from refolding experiments. At approximately 1 M Gu-HCl the aggregation was found to be essentially complete. The size and structure of the aggregates could be varied by changing the protein concentration. EPR measurements and line-shape simulations together with fluorescence lifetime and anisotropy measurements provided a picture of the self-assembled protein as a disordered protein structure with a representation of both compact as well as dynamic and polar environments at the site of the molecular labels. This suggests that a partially folded intermediate of HCA II self-assembles by both local unfolding and intermolecular docking of the intermediates vicinal to position 79. The aggregates were determined to be 40-90 A in diameter depending on the experimental conditions and spectroscopic technique used.
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Affiliation(s)
- P Hammarström
- Department of Chemistry, Linköping University, SE-581 83 Linköping, Sweden
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12
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Osterlund M, Owenius R, Carlsson K, Carlsson U, Persson E, Lindgren M, Freskgård PO, Svensson M. Probing inhibitor-induced conformational changes along the interface between tissue factor and factor VIIa. Biochemistry 2001; 40:9324-8. [PMID: 11478900 DOI: 10.1021/bi010283n] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Upon injury of a blood vessel, activated factor VII (FVIIa) forms a high-affinity complex with its allosteric regulator, tissue factor (TF), and initiates blood clotting. Active site-inhibited factor VIIa (FVIIai) binds to TF with even higher affinity. We compared the interactions of FVIIai and FVIIa with soluble TF (sTF). Six residues in sTF were individually selected for mutagenesis and site-directed labeling. The residues are distributed along the extensive binding interface, and were chosen because they are known to interact with the different domains of FVIIa. Fluorescent and spin probes were attached to engineered Cys residues to monitor local changes in hydrophobicity, accessibility, and rigidity in the sTF--FVIIa complex upon occupation of the active site of FVIIa. The results show that inhibition of FVIIa caused the structures around the positions in sTF that interact with the protease domain of FVIIa to become more rigid and less accessible to solvent. Thus, the presence of an active site inhibitor renders the interface in this region less flexible and more compact, whereas the interface between sTF and the light chain of FVIIa is unaffected by active site occupancy.
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Affiliation(s)
- M Osterlund
- IFM-Department of Chemistry, Linköping University, Linköping, Sweden
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13
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Hammarstrom P, Persson M, Carlsson U. Protein compactness measured by fluorescence resonance energy transfer. Human carbonic anhydrase ii is considerably expanded by the interaction of GroEL. J Biol Chem 2001; 276:21765-75. [PMID: 11278767 DOI: 10.1074/jbc.m010858200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [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: 01/13/2023] Open
Abstract
Nine single-cysteine mutants were labeled with 5-(2-iodoacetylaminoethylamino)naphthalene-1-sulfonic acid, an efficient acceptor of Trp fluorescence in fluorescence resonance energy transfer. The ratio between the fluorescence intensity of the 5-(2-acetylaminoethylamino)naphthalene-1-sulfonic acid (AEDANS) moiety excited at 295 nm (Trp absorption) and 350 nm (direct AEDANS absorption) was used to estimate the average distances between the seven Trp residues in human carbonic anhydrase II (HCA II) and the AEDANS label. Guanidine HCl denaturation of the HCA II variants was also performed to obtain a curve that reflected the compactness of the protein at various stages of the unfolding, which could serve as a scale of the expansion of the protein. This approach was developed in this study and was used to estimate the compactness of HCA II during heat denaturation and interaction with GroEL. It was shown that thermally induced unfolding of HCA II proceeded only to the molten globule state. Reaching this state was sufficient to allow HCA II to bind to GroEL, and the volume of the molten globule intermediate increased approximately 2.2-fold compared with that of the native state. GroEL-bound HCA II expands to a volume three to four times that of the native state (to approximately 117,000 A(3)), which correlates well with a stretched and loosened-up HCA II molecule in an enlarged GroEL cavity. Recently, we found that HCA II binding causes such an inflation of the GroEL molecule, and this probably represents the mechanism by which GroEL actively stretches its protein substrates apart (Hammarström, P., Persson, M., Owenius, R., Lindgren, M., and Carlsson, U. (2000) J. Biol. Chem. 275, 22832-22838), thereby facilitating rearrangement of misfolded structure.
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Affiliation(s)
- P Hammarstrom
- IFM-Department of Chemistry, Linköping University, SE-581 83 Linköping, Sweden
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14
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Carlsson U. [A wish to change the tradition]. Lakartidningen 2001; 98:2372. [PMID: 11402999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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15
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Carlsson U. [Children's rights and medical ethics]. Lakartidningen 2001; 98:1573. [PMID: 11330162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
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16
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Andersson D, Hammarström P, Carlsson U. Cofactor-induced refolding: refolding of molten globule carbonic anhydrase induced by Zn(II) and Co(II). Biochemistry 2001; 40:2653-61. [PMID: 11258876 DOI: 10.1021/bi000957e] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [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: 11/29/2022]
Abstract
The stability versus unfolding to the molten globule intermediate of bovine carbonic anhydrase II (BCA II) in guanidine hydrochloride (GuHCl) was found to depend on the metal ion cofactor [Zn(II) or Co(II)], and the apoenzyme was observed to be least stable. Therefore, it was possible to find a denaturant concentration (1.2 M GuHCl) at which refolding from the molten globule to the native state could be initiated merely by adding the metal ion to the apo molten globule. Thus, refolding could be performed without changing the concentration of the denaturant. The molten globule intermediate of BCA II could still bind the metal cofactor. Cofactor-effected refolding from the molten globule to the native state can be summarized as follows: (1) initially, the metal ion binds to the molten globule; (2) compaction of the metal-binding site region is then induced by the metal ion binding; (3) a functioning active center is formed; and (4) finally, the native tertiary structure is generated in the outer parts of the protein.
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Affiliation(s)
- D Andersson
- IFM-Department of Chemistry, Linköping University, SE-581 83 Linköping, Sweden
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17
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Andersson D, Carlsson U, Freskgård PO. Contribution of tryptophan residues to the CD spectrum of the extracellular domain of human tissue factor: application in folding studies and prediction of secondary structure. Eur J Biochem 2001; 268:1118-28. [PMID: 11179978 DOI: 10.1046/j.1432-1327.2001.01981.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The contribution to the circular dichroism (CD) spectrum made by each of the four Trp residues in the extracellular domain of human tissue factor, sTF (s designates soluble), was determined from difference CD spectra. The individual Trp CD spectra showed that all four residues contributed to the CD spectrum in almost the entire wavelength region investigated (180-305 nm). The sum of the individual spectra of each Trp residue in the near-UV region was qualitatively identical to the wild-type spectrum, clearly demonstrating that the Trp residues are the major contributors to the spectrum in this wavelength region. Trp CD bands interfere with the peptide bands in the far-UV region, leading to uncertainty in the predictions of the amounts of various types of secondary structure. Accordingly, the best prediction of secondary sTF structure content was achieved using a hypothetical Trp-free CD spectrum obtained after subtraction of all individual Trp spectra from the wild-type spectrum. The mutated Trp residues were also exploited as intrinsic probes to monitor the formation of local native-like tertiary structure by kinetic near-UV CD measurements. The global folding reaction was followed in parallel with a novel functional assay that registered the recovery of cofactor activity, i.e. stimulation of the amidolytic activity of Factor VIIa. From these measurements, it was found that sTF appears to regain FVIIa cofactor activity before the final side-chain packing of the Trp residues. The combined kinetic refolding results suggest that the compact asymmetric environments of the individual Trp residues in sTF are formed simultaneously, leading to the conclusion that the native tertiary structure of the whole protein is formed in a cooperative manner.
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Affiliation(s)
- D Andersson
- IFM-Department of Chemistry, Linköping University, Sweden
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18
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Abstract
In the present study, the torque or work produced during isometric, pure concentric and eccentric-concentric plantar flexions, performed in sitting, standing and prone were measured. The electromyographic (EMG) activity was measured from the soleus, gastrocnemius medialis, tibialis anterior and rectus femoris muscles. The isometric tests showed the highest torques in the standing test. The rectus femoris and gastrocnemius activities were lower in the prone than in the standing test. The sitting test showed lower activities in all muscles of the lower leg compared with the standing test. No differences in work between the prone and sitting tests were found during the concentric phases. Higher rectus femoris activity in the eccentric-concentric test and lower activity in the triceps surae during the concentric phases were seen in the sitting compared with the prone test. We conclude that tests of overall functional ability should be performed in the standing position while specific tests of the plantar flexors should be performed in the prone position.
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Affiliation(s)
- U Carlsson
- Department of Rehabilitation Medicine, Göteborg University, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden
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19
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Vince JW, Carlsson U, Reithmeier RA. Localization of the Cl-/HCO3- anion exchanger binding site to the amino-terminal region of carbonic anhydrase II. Biochemistry 2000; 39:13344-9. [PMID: 11063570 DOI: 10.1021/bi0015111] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [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: 11/28/2022]
Abstract
Human carbonic anhydrase II (CAII) possesses a binding site for an acidic motif (D887ADD) within the carboxyl-terminal region (Ct) of the human erythrocyte chloride/bicarbonate anion exchanger, AE1. In this study, the amino acid sequence comprising this AE1 binding site was localized to the first 17 residues of CAII, which form a basic patch on the surface of the protein. Truncation of the amino terminal of CAII by five residues resulted in a 3-fold reduction in the apparent affinity of the interaction with a GST fusion protein of the Ct of AE1 (GST-Ct) measured by a sensitive microtiter plate binding assay. Further amino-terminal truncation of CAII by 17 or 24 residues caused a loss of binding. The homologous isoform CAI does not bind AE1, despite having 60% sequence identity to CAII. One major difference between the two CA isoforms, within the amino-terminal region, is a high content of histidine residues in CAII (His3, -4, -10, -15, -17) not found in CAI. Mutation of pairs of these histidines (and one lysine) in CAII to the analogous residues in CAI (H3P/H4D or K9D/H10K or H15Q/H17S), or combinations of these various double mutants, did not greatly affect binding between GST-Ct and the mutant CAII. However, when all six of the targeted CAII residues were mutated to the corresponding sequence in CAI, binding of GST-Ct was lost. These results indicate that the AE1 binding site is located within the first 17 residues of CAII, and that the interaction is mediated by electrostatic interactions involving histidine and/or lysine residues. Further specificity for the interaction of AE1 and CAII is provided by a conserved leucine residue (L886) in AE1 that, when mutated to alanine, resulted in loss of GST-Ct binding to immobilized CAII. The binding of the basic amino-terminal region of CAII to an acidic Ct in AE1 provides a structural basis for linking bicarbonate transport across the cell membrane to intracellular bicarbonate metabolism.
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Affiliation(s)
- J W Vince
- Medical Research Council Group in Membrane Biology, Departments of Medicine and Biochemistry, Room 7344, Medical Sciences Building, University of Toronto, Toronto, Ontario, Canada M5S 1A8
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20
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Abstract
The postural function in 52 patients with normal pressure hydrocephalus (NPH) and in 19 patients with subcortical arteriosclerotic encephalopathy (SAE) was analysed bedside and in 17 of the NPH, 10 of the SAE and 23 healthy individuals (HI) also examined with a force platform. At the bedside examination, no differences in postural functions between NPH and SAE patients were found. The NPH patients improved more in the postural than in motor functions after shunt surgery. The NPH patients had a larger sway area and a higher backward directed velocity of centre of pressure than HI. The direction of the inclination in the sagittal plane was neutral or forward in the NPH and the SAE patients while it was backward in HI. The postural function was better in positions with open eyes in all 3 groups, but significantly less in the NPH patients, indicating a misinterpretation of afferent visual stimuli in the brainstem postural centre.
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Affiliation(s)
- E Blomsterwall
- Department of Physiotherapy, Sahlgrenska University Hospital, Göteborg University, Sweden.
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21
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Osterlund M, Owenius R, Persson E, Lindgren M, Carlsson U, Freskgård PO, Svensson M. Spectroscopic probing of the influence of calcium and the gla domain on the interaction between the first EGF domain in factor VIIa and tissue factor. Eur J Biochem 2000; 267:6204-11. [PMID: 11012674 DOI: 10.1046/j.1432-1327.2000.01693.x] [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: 11/20/2022]
Abstract
The binding of factor VIIa (FVIIa) to tissue factor (TF) initiates blood coagulation. The binary complex is dependent on Ca2+ binding to several sites in FVIIa and is maintained by multiple contacts distributed throughout the various domains. Although the contributions from various residues and domains, including the Ca2+ coordination, to the global binding energy have been characterized, their importance for specific local interactions is virtually unknown. To address this aspect, we have attached four spectroscopic probes to an engineered Cys residue replacing Phe140 in soluble TF (sTF). This allows the monitoring of local changes in hydrophobicity and rigidity upon complex formation at the interface between the first epidermal growth factor-like (EGF1) domain of FVIIa and sTF. The fluorescent labels used sense a more hydrophobic environment and the spin labels are dramatically immobilized when FVIIa binds sTF. The results obtained with a 4-carboxyglutamic acid (Gla)-domainless derivative of FVIIa indicate that the Gla domain has no or minimal influence on the interaction between EGF1 and sTF. However, there is a difference in local Ca2+ dependence between Gla-domainless and full-length FVIIa.
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Affiliation(s)
- M Osterlund
- IFM-Department of Chemistry, and IFM-Department of Chemical Physics, Linköping University, Sweden; Tissue Factor/Factor VII Research, Novo Nordisk A/S, Mâlov, Denmark
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22
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Abstract
Solving the protein folding problem is one of the most challenging tasks in the post genomic era. Identification of folding-initiation sites is very important in order to understand the protein folding mechanism. Detection of residual structure in unfolded proteins can yield important clues to the initiation sites in protein folding. A substantial number of studied proteins possess residual structure in hydrophobic regions clustered together in the protein core. These stable structures can work as seeds in the folding process. In addition, local preferences for secondary structure in the form of turns for beta-sheet initiation and helical turns for alpha-helix formation can guide the folding reaction. In this respect the unfolded states, studied at increasing structural resolution, can be the Rosetta Stone of the protein folding problem.
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Affiliation(s)
- P Hammarström
- IFM-Department of Chemistry, Linköping University, Linköping, S-581 83, Sweden
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23
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Hammarström P, Persson M, Owenius R, Lindgren M, Carlsson U. Protein substrate binding induces conformational changes in the chaperonin GroEL. A suggested mechanism for unfoldase activity. J Biol Chem 2000; 275:22832-8. [PMID: 10811634 DOI: 10.1074/jbc.m000649200] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [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: 11/06/2022] Open
Abstract
Chaperonins are molecules that assist proteins during folding and protect them from irreversible aggregation. We studied the chaperonin GroEL and its interaction with the enzyme human carbonic anhydrase II (HCA II), which induces unfolding of the enzyme. We focused on conformational changes that occur in GroEL during formation of the GroEL-HCA II complex. We measured the rate of GroEL cysteine reactivity toward iodo[2-(14)C]acetic acid and found that the cysteines become more accessible during binding of a cysteine free mutant of HCA II. Spin labeling of GroEL with N-(1-oxyl-2,2,5, 5-tetramethyl-3-pyrrolidinyl)iodoacetamide revealed that this additional binding occurred because buried cysteine residues become accessible during HCA II binding. In addition, a GroEL variant labeled with 6-iodoacetamidofluorescein exhibited decreased fluorescence anisotropy upon HCA II binding, which resembles the effect of GroES/ATP binding. Furthermore, by producing cysteine-modified GroEL with the spin label N-(1-oxyl-2,2,5, 5-tetramethyl-3-pyrrolidinyl)iodoacetamide and the fluorescent label 5-((((2-iodoacetyl)amino)ethyl)amino)naphthalene-1-sulfonic acid, we detected increases in spin-label mobility and fluorescence intensity in GroEL upon HCA II binding. Together, these results show that conformational changes occur in the chaperonin as a consequence of protein substrate binding. Together with previous results on the unfoldase activity of GroEL, we suggest that the chaperonin opens up as the substrate protein binds. This opening mechanism may induce stretching of the protein, which would account for reported unfoldase activity of GroEL and might explain how GroEL can actively chaperone proteins larger than HCA II.
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Affiliation(s)
- P Hammarström
- IFM Department of Chemistry and Chemical Physics, Linköping University, S-581 83 Linköping, Sweden
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24
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Svantesson U, Takahashi H, Carlsson U, Danielsson A, Sunnerhagen KS. Muscle and tendon stiffness in patients with upper motor neuron lesion following a stroke. Eur J Appl Physiol 2000; 82:275-9. [PMID: 10958369 DOI: 10.1007/s004210000216] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [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: 11/26/2022]
Abstract
The objective of this study was to investigate muscle and tendon stiffness in the triceps surae muscles in patients who had previously had a stroke. The participants were 12 men showing slight to moderate degrees of muscle tonus in the affected leg. All patients showed minimal or no overt clinical motor symptoms, and all walked without mechanical aid. Muscle strengths in isometric and isokinetic activities were measured, as was passive resistance during plantarflexion in each leg. Walking speed was also measured. Evaluations of physical performance and muscle tone were made. Muscle and tendon stiffness was calculated from measurements whilst passively stretching during electrical stimulation, separately for each leg. Muscle strength was significantly higher in the non-affected than in the affected leg. Muscle stiffness was significantly higher in the affected leg than in the non-affected leg. Tendon stiffness was significantly higher in the non-affected than in the affected leg. The higher muscle stiffness in the affected leg might enhance the possibility for storing elastic energy during preactivation. Lower tendon stiffness in the affected leg might reduce the development of fatigue in movements at low velocities.
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Affiliation(s)
- U Svantesson
- Göteborg University, Department of Rehabilitation Medicine, Sahlgrenska University Hospital, Sweden.
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25
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Sunnerhagen KS, Carlsson U, Sandberg A, Stålberg E, Hedberg M, Grimby G. Electrophysiologic evaluation of muscle fatigue development and recovery in late polio. Arch Phys Med Rehabil 2000; 81:770-6. [PMID: 10857522] [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: 02/16/2023]
Abstract
OBJECTIVES To study aspects of fatigue in late-polio patients and healthy controls. We hypothesized that late-polio subjects would develop more peripheral fatigue, assessed with surface electromyography (EMG), and that no major differences would exist between the two groups in neuromuscular junction transmission. DESIGN Case-control study. SETTING University hospital laboratory. SUBJECTS Ten patients with a history of polio (mean age, 54 yrs, SD = 5; mean time since polio onset, 49 yrs, SD = 7) and a matched control group (mean age, 52 yrs, SD = 8). METHODS A protocol with a stepwise force increase up to 80% of maximal voluntary contraction ending with an 8-minute recovery period was performed twice, first with surface EMG and then with electrical stimulation and surface-recorded evoked M-response. MAIN OUTCOME MEASURES Surface EMG analysis of voluntary activity and evoked M-response. RESULTS No significant differences existed between groups in the relative decrease during the fatigue protocol. The recovery of force was slower in the late-polio subjects. A reduction in the root mean square (RMS) value during recovery was seen in the polio group, although a normalization of the mean power frequency (MPF) was seen in both groups. CONCLUSION The weakness during the fatigue procedure was not caused by neuromuscular blockade, because electrical nerve stimulation evoked a normal response. The weakness after exercise was the result of a slow recovery that may reflect both central and peripheral fatigue.
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Affiliation(s)
- K S Sunnerhagen
- Department of Rehabilitation Medicine, Göteborg University, Sweden
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26
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Affiliation(s)
- U Carlsson
- IFM-Department of Chemistry, Linköping University, S-581 83 Linköping, Sweden
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27
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Hammarström P, Persson M, Freskgârd PO, Mârtensson LG, Andersson D, Jonsson BH, Carlsson U. Structural mapping of an aggregation nucleation site in a molten globule intermediate. J Biol Chem 1999; 274:32897-903. [PMID: 10551854 DOI: 10.1074/jbc.274.46.32897] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [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: 11/06/2022] Open
Abstract
Protein aggregation plays an important role in biotechnology and also causes numerous diseases. Human carbonic anhydrase II is a suitable model protein for studying the mechanism of aggregation. We found that a molten globule state of the enzyme formed aggregates. The intermolecular interactions involved in aggregate formation were localized in a direct way by measuring excimer formation between each of 20 site-specific pyrene-labeled cysteine mutants. The contact area of the aggregated protein was very specific, and all sites included in the intermolecular interactions were located in the large beta-sheet of the protein, within a limited region between the central beta-strands 4 and 7. This substructure is very hydrophobic, which underlines the importance of hydrophobic interactions between specific beta-sheet containing regions in aggregate formation.
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Affiliation(s)
- P Hammarström
- Department of Physics Measurement Technology, Linköping University, SE-581 83 Linköping, Sweden
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28
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Owenius R, Osterlund M, Lindgren M, Svensson M, Olsen OH, Persson E, Freskgård PO, Carlsson U. Properties of spin and fluorescent labels at a receptor-ligand interface. Biophys J 1999; 77:2237-50. [PMID: 10512843 PMCID: PMC1300504 DOI: 10.1016/s0006-3495(99)77064-5] [Citation(s) in RCA: 43] [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: 11/16/2022] Open
Abstract
Site-directed labeling was used to obtain local information on the binding interface in a receptor-ligand complex. As a model we have chosen the specific association of the extracellular part of tissue factor (sTF) and factor VIIa (FVIIa), the primary initiator of the blood coagulation cascade. Different spectroscopic labels were covalently attached to an engineered cysteine in position 140 in sTF, a position normally occupied by a Phe residue previously characterized as an important contributor to the sTF:FVIIa interaction. Two spin labels, IPSL [N-(1-oxyl-2,2,5, 5-tetramethyl-3-pyrrolidinyl)iodoacetamide] and MTSSL [(1-oxyl-2,2,5, 5-tetramethylpyrroline-3-methyl)methanethiosulfonate], and two fluorescent labels, IAEDANS [5-((((2-iodoacetyl)amino) ethyl)amino)naphthalene-1-sulfonic acid] and BADAN [6-bromoacetyl-2-dimethylaminonaphthalene], were used. Spectral data from electron paramagnetic resonance (EPR) and fluorescence spectroscopy showed a substantial change in the local environment of all labels when the sTF:FVIIa complex was formed. However, the interaction was probed differently by each label and these differences in spectral appearance could be attributed to differences in label properties such as size, polarity, and/or flexibility. Accordingly, molecular modeling data suggest that the most favorable orientations are unique for each label. Furthermore, line-shape simulations of EPR spectra and calculations based on fluorescence depolarization measurements provided additional details of the local environment of the labels, thereby confirming a tight protein-protein interaction between FVIIa and sTF when the complex is formed. The tightness of this local interaction is similar to that seen in the interior of globular proteins.
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Affiliation(s)
- R Owenius
- IFM-Department of Chemical Physics, Linköping University, SE-581 83 Linköping, Sweden
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29
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Abstract
Altogether 218 sheep sera from 40 flocks in different parts of Sweden were screened for antibodies to bovine coronavirus (BCV). Nineteen per cent of the sera were positive and there was a significantly higher frequency (p < 0.05) of at least one positive sample in flocks with more than 100 adult sheep than in smaller flocks. There was also a significantly higher frequency (p < 0.001) of positive samples from sheep older than 4 years than from younger ones. Only a weak relationship between BCV positivity (2 or more positive samples, p < 0.05) and cattle contact was demonstrated in this study. Possible transmission routes and other factors that could have affected the result are discussed. In light of our finding that all 5 sheep experimentally exposed to BCV through contact with infectious cow faeces seroconverted, we conclude that the antibodies found in Swedish sheep are probably the result of BCV infections directly or indirectly transmitted from cattle.
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30
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Borén K, Andersson P, Larsson M, Carlsson U. Characterization of a molten globule state of bovine carbonic anhydrase III: loss of asymmetrical environment of the aromatic residues has a profound effect on both the near- and far-UV CD spectrum. Biochim Biophys Acta 1999; 1430:111-8. [PMID: 10082939 DOI: 10.1016/s0167-4838(98)00283-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Bovine muscle carbonic anhydrase (isoenzyme III; BCAIII) exhibited a three-state unfolding process at equilibrium upon denaturation in guanidine hydrochloride (GuHCl). The stable folding intermediate appeared to be of molten globule type. The stability towards GuHCl in terms of mid-point concentrations of denaturation were very similar for BCAIII and human CAII (HCAII). It was further demonstrated that the aromatic amino acid residues contributed significantly to the circular dichroism (CD) spectrum in the far-UV wavelength region during the native-->molten globule state transition. Thus, the ellipiticity change at 218 nm was shown to monitor the loss of tertiary interactions of aromatic side chains at the first unfolding transition as well as the rupture of secondary structure at the second unfolding transition. Similar aromatic contributions to the far-UV CD spectrum, but with varying magnitudes, were also noted for BCAII and HCAII, further emphasizing that interference of aromatic residues should not be neglected at wavelengths that normally are assigned to secondary structural changes.
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Affiliation(s)
- K Borén
- IFM/Department of Chemistry, Linköping University, SE-581 83, Linköping, Sweden
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31
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Persson M, Hammarström P, Lindgren M, Jonsson BH, Svensson M, Carlsson U. EPR mapping of interactions between spin-labeled variants of human carbonic anhydrase II and GroEL: evidence for increased flexibility of the hydrophobic core by the interaction. Biochemistry 1999; 38:432-41. [PMID: 9890926 DOI: 10.1021/bi981442e] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [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
Human carbonic anhydrase II (HCA II) interacts weakly with GroEL at room temperature. To further investigate this interaction we used electron paramagnetic resonance (EPR) spectroscopy to study HCA II cysteine mutants spin-labeled at selected positions. From our results it is evident that protein-protein interactions can be specifically mapped by site-directed spin-labeling and EPR measurements. HCA II needs to be unfolded to about the same extent as a GuHCl-induced molten-globule intermediate of the enzyme to interact with GroEL. The interaction with GroEL includes interactions with outer parts of the HCA II molecule, such as peripheral beta-strands and the N-terminal domain, which have previously been shown to be rather unstable. As a result of the interaction, the rigid and compact hydrophobic core exhibits higher flexibility than in the molten globule, which is likely to facilitate rearrangements of misfolded structure during the folding process. The degree of binding to GroEL and accompanying inactivation of the enzyme depend on the stability of the HCA II variant, and nonspecific hydrophobic interactions appear to be most important in stabilizing the GroEL-substrate complex.
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Affiliation(s)
- M Persson
- IFM-Department of Chemistry, Linköping University, Sweden
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32
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Tråvén M, Carlsson U, Lundén A, Larsson B. Serum antibodies to bovine coronavirus in Swedish sheep. Acta Vet Scand 1999; 40:69-74. [PMID: 10418197 PMCID: PMC8043158] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/1998] [Accepted: 12/07/1998] [Indexed: 02/13/2023] Open
Abstract
Altogether 218 sheep sera from 40 flocks in different parts of Sweden were screened for antibodies to bovine coronavirus (BCV). Nineteen per cent of the sera were positive and there was a significantly higher frequency (p < 0.05) of at least one positive sample in flocks with more than 100 adult sheep than in smaller flocks. There was also a significantly higher frequency (p < 0.001) of positive samples from sheep older than 4 years than from younger ones. Only a weak relationship between BCV positivity (2 or more positive samples, p < 0.05) and cattle contact was demonstrated in this study. Possible transmission routes and other factors that could have affected the result are discussed. In light of our finding that all 5 sheep experimentally exposed to BCV through contact with infectious cow faeces seroconverted, we conclude that the antibodies found in Swedish sheep are probably the result of BCV infections directly or indirectly transmitted from cattle.
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Affiliation(s)
- M. Tråvén
- Department of Ruminant Medicine and Veterinary Epidemiology, Section of Ruminant Medicine, P.O. Box 7019, S-750 07 Uppsala, Sweden
| | - U. Carlsson
- Department of Ruminant Medicine and Veterinary Epidemiology, Section of Ruminant Medicine, P.O. Box 7019, S-750 07 Uppsala, Sweden
| | - A. Lundén
- Department of Veterinary Microbiology, Section of Parasitology, Swedish University of Agricultural Sciences, Uppsala, USA
| | - B. Larsson
- Swedish Board of Agriculture, Jönköping, Sweden
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33
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Svantesson U, Carlsson U, Takahashi H, Thomée R, Grimby G. Comparison of muscle and tendon stiffness, jumping ability, muscle strength and fatigue in the plantar flexors. Scand J Med Sci Sports 1998; 8:252-6. [PMID: 9809382 DOI: 10.1111/j.1600-0838.1998.tb00479.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An isokinetic dynamometer was used to measure plantar flexion muscle strength at 60 degrees/s and 200 degrees/s in 10 healthy young men (mean age 25 years). Muscle and tendon stiffnesses were determined on the dynamometer by the use of electrical stimulation and passive stretch (200 degrees/s). Differences in jumping heights between squat and counter-movement jumps were calculated from flight times. The number of heel-rises performed until exhaustion, standing on one leg, were counted. Stepwise regression analysis showed that differences in jumping height increased with lower muscle strength and with higher muscle and tendon stiffnesses, indicating that elastic components may be of more importance in persons with lower muscle strength. The number of heel-rises was negatively dependant on tendon stiffness, indicating that increased stiffness may enhance the development of fatigue.
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Affiliation(s)
- U Svantesson
- Department of Rehabilitation Medicine, Sahlgrenska University Hospital, Göteborg University, Sweden
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34
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Hammarström P, Kalman B, Jonsson BH, Carlsson U. Pyrene excimer fluorescence as a proximity probe for investigation of residual structure in the unfolded state of human carbonic anhydrase II. FEBS Lett 1997; 420:63-8. [PMID: 9450551 DOI: 10.1016/s0014-5793(97)01488-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [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: 02/05/2023]
Abstract
The excimer fluorescence from two pyrenyl moieties attached to cysteines in human carbonic anhydrase II has been monitored to characterize residual structure retained under strong denaturing conditions. A position in beta-strand 3, N67C, together with the single naturally occurring cysteine 206 in beta-strand 7, were used as attachment sites. The eximer formation by the pyrenyls, requiring proximity of the probes, revealed an unfolding transition at a GuHCl concentration significantly higher than that required to induce unfolding of the molten globule state as monitored by CD. These results indicate that the excimer transition monitors the unfolding of a residual compact structure that spans beta-strands 3-7. This region constitutes the central and the most hydrophobic part of the molecule, emphasizing the importance of hydrophobic interaction in maintaining residual structure under strong unfolding conditions.
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Affiliation(s)
- P Hammarström
- IFM-Department of Chemistry, Linköping University, Sweden
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35
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Persson M, Carlsson U, Bergenhem N. GroEL provides a folding pathway with lower apparent activation energy compared to spontaneous refolding of human carbonic anhydrase II. FEBS Lett 1997; 411:43-7. [PMID: 9247139 DOI: 10.1016/s0014-5793(97)00663-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The kinetics of the refolding of the enzyme, human carbonic anhydrase II (HCA II), at different temperatures, together with the Escherichia coli chaperonin GroEL, has been studied. The Arrhenius plots for the spontaneous, GroEL-assisted, and GroEL/ES-assisted refolding of HCA II show that the apparent activation energy (E(a)) is lower in the presence of the chaperonin GroEL alone than for the spontaneous reaction, whereas the apparent activation energy for the GroEL/ES-assisted reaction is almost the same as for the spontaneous reaction (85, 46, and 72 kJ/mol, for the spontaneous, GroEL, and GroEL/ES-assisted reactions, respectively).
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Affiliation(s)
- M Persson
- IFM/Department of Chemistry, Linköping University, Sweden
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36
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Jonasson P, Aronsson G, Carlsson U, Jonsson BH. Tertiary structure formation at specific tryptophan side chains in the refolding of human carbonic anhydrase II. Biochemistry 1997; 36:5142-8. [PMID: 9136875 DOI: 10.1021/bi961882a] [Citation(s) in RCA: 28] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The refolding reaction of human carbonic anhydrase II has been characterized by use of seven variants in which tryptophan residues have been replaced by Phe or Cys, in each case giving proteins with six tryptophans. Intrinsic tryptophan fluorescence was used to monitor the refolding in the 2 ms-60 s time range, and kinetic traces showing the contributions from each particular tryptophan were obtained by calculation of differences between the wild-type protein and the variants. Earlier assignment [Mårtensson, L.-G., Jonasson, P., Freskgard, P.-O., Svensson, M., Carlsson, U., & Jonsson, B.-H. (1995) Biochemistry 34, 1011-1021] of specific fluorescence properties to each tryptophan, especially regarding energy transfer and intrinsic fluorescence quenching, has made it possible to use the kinetic data to describe the formation of tertiary structure at defined tryptophan residues. In summary, it was found that tertiary structure is formed earlier at those tryptophans that are associated with the central core of beta-strands than at tryptophan residues in the N-terminal minidomain.
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Affiliation(s)
- P Jonasson
- Department of Biochemistry, Umeå University, Sweden
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37
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Andersson D, Freskgård PO, Jonsson BH, Carlsson U. Formation of local native-like tertiary structures in the slow refolding reaction of human carbonic anhydrase II as monitored by circular dichroism on tryptophan mutants. Biochemistry 1997; 36:4623-30. [PMID: 9109672 DOI: 10.1021/bi961925n] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [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: 02/04/2023]
Abstract
In the present study, near-UV CD kinetic measurements on mutants, in which one Trp residue had been replaced, were performed to probe the development of asymmetric environments around specific Trp residues during the refolding of human carbonic anhydrase II (HCAII). In addition, the formation of the active site was probed by the binding of a fluorescent sulfonamide inhibitor. The development of the individual Trp CD spectra during refolding was obtained by subtracting the CD spectrum of the mutant lacking one Trp from that of HCAII at different time points. The same method was used for the particular Trp residues to obtain the kinetic CD traces monitored at a specific wavelength (270 nm). Trp residues 16, 97, and 245 were analyzed. Trp16 probes the N-terminal domain (amino acid residues 1-25), and this part is forming its tertiary structure slower than the major domain (amino acid residues 26-260) of the protein molecule, which contains the active site and a dominating beta-sheet. An essentially native structure of the major domain seems to act as a template for the correct folding of the N terminus. Trp97 is located in a hydrophobic cluster comprising beta-strands 3-5 in the protein core. Previously, we have shown that this region is remarkably stable and compact, and stopped-flow fluorescence data indicate that Trp97 is buried in an apolar compact cluster within a few milliseconds [Svensson, M., Jonasson, P., Freskgård, P.-O., Jonsson, B.-H., Lindgren, M., Martensson, L.-G., Gentile, M., Bóren, K., & Carlsson, U. (1995) Biochemistry 34, 8606-8620; Jonasson, P., Aronsson, G., Carlsson, U., & Jonsson, B.-H. (1997) Biochemistry 36 (in press)]. Here it is shown that the development of the native tertiary structure at Trp97 occurs in the minute time domain. Trp245 is located in a long loop between the N-terminal domain and the core structure. Although this Trp has attained native-like fluorescence properties within the dead time of the CD experiment, it assumes a native-like asymmetric environment even slower than Trp97. Thus, the investigated Trp residues develop their native CD bands at different rates, showing that formation of native-like tertiary structure is occurring with varying rates in different regions of the protein.
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Affiliation(s)
- D Andersson
- IFM-Department of Chemistry, Linköping University, Sweden
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38
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Billsten P, Freskgård PO, Carlsson U, Jonsson BH, Elwing H. Adsorption to silica nanoparticles of human carbonic anhydrase II and truncated forms induce a molten-globule-like structure. FEBS Lett 1997; 402:67-72. [PMID: 9013861 DOI: 10.1016/s0014-5793(96)01431-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [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: 02/03/2023]
Abstract
Human carbonic anhydrase II pseudo-wild type (HCAIIpwt) and two truncated variants were adsorbed to approximately 9 nm silica nanoparticles. Ellipsometry was used as an indirect measure of protein adsorption. The structural changes of adsorbed proteins were investigated with the use of circular dichroism (CD), intrinsic fluorescence, ANS binding ability and inhibitor binding capacity. It was found that the variants that were truncated at positions 5 and 17 in the N-terminal end attain a molten-globule-like state after interaction with the silica nanoparticles. In contrast, the more stable HCAIIpwt retained most of its native structure after 24 h adsorption to silica nanoparticles. The result suggests that surface induced unfolding may give rise to intermediates similar to those for unfolding induced by, for example GuHCl. Thus, the intermediate observed has some features of the molten globule.
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Affiliation(s)
- P Billsten
- IFM-Laboratory of Applied Physics, University of Linköping, Sweden.
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Persson M, Carlsson U, Bergenhem NC. GroEL reversibly binds to, and causes rapid inactivation of, human carbonic anhydrase II at high temperatures. Biochim Biophys Acta 1996; 1298:191-8. [PMID: 8980645 DOI: 10.1016/s0167-4838(96)00125-2] [Citation(s) in RCA: 19] [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] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The initial yield of reactivation of GuHCl denatured human carbonic anhydrase II does not change with temperature between 3 and 35 degrees C. At temperatures above 35 degrees C, the enzymatic activity is not stable, but decreases over time. If the bacterial chaperonin GroEL is present during reactivation, the initial yield is lower compared to the spontaneous reaction at temperatures of 35-50 degrees C. However, unlike the spontaneous reactivation, the enzymatic activity with time in the presence of GroEL. In the presence of GroEL, native HCA II incubated at elevated temperatures will rapidly loose enzymatic activity to the same value as during reactivation at that particular temperature; most of the activity will recover if the temperature is lowered when GroEL is present. It is evident that there is an equilibrium between an inactive intermediate of HCA II, probably bound to GroEL, and active enzyme. Furthermore, proline isomerization is part of the rate-limiting step of refolding even in the presence of GroEL, and it is very noteworthy that prolyl isomerase will influence the refolding of HCA II in the presence of GroEL.
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Affiliation(s)
- M Persson
- IFM/Dept. of Chemistry, Linköping University, Sweden
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Borén K, Freskgård PO, Carlsson U. A comparative CD study of carbonic anhydrase isoenzymes with different number of tryptophans: impact on calculation of secondary structure content. Protein Sci 1996; 5:2479-84. [PMID: 8976556 PMCID: PMC2143327 DOI: 10.1002/pro.5560051210] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [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: 02/03/2023]
Abstract
The CD spectra of human carbonic anhydrase I and II and bovine carbonic anhydrase III were recorded and analyzed. The 3D structures of these isoenzymes are known, showing very similar secondary structure and polypeptide-chain fold. The tryptophan content, however, differs between the isoenzymes, i.e., isoenzymes I, II, and III possess 6, 7, and 8 tryptophans, respectively. All of the tryptophans except the additional tryptophans in isoenzymes II and III, i.e., W245 and W47, are conserved. Despite the fact that X-ray structure determinations showed that the isoenzymes had highly similar secondary structure, the contents of alpha-helix and beta-sheet structure differed considerably when using different CD algorithms for estimation of the fractions of various secondary structural elements. This shows that aromatic amino acids also interfere in the wavelength region (far-UV) used to calculate the amount of secondary structure. Such interference is especially problematic when analyzing proteins like carbonic anhydrase, which consist mainly of beta-structure that gives rise to weak ellipticity bands, compared to the bands arising from alpha-helical structure.
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Affiliation(s)
- K Borén
- IFM-Department of Chemistry, Linköping University, Sweden
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41
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Carlsson U. ["The best for the Children"--a paradoxical concept]. Lakartidningen 1996; 93:1512. [PMID: 8667746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Carlsson U, Brudin L, Eliasson I, Hansson BG. Hepatitis A vaccination by intracutaneous low dose administration: a less expensive alternative. Scand J Infect Dis 1996; 28:435-8. [PMID: 8953668 DOI: 10.3109/00365549609037934] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We investigated the immune response to three different intracutaneous (i.c.) doses of inactivated hepatitis A vaccine: 72, 144, and 216 ELISA units (EU). The response was measured using a quotient score derived from a commercial enzyme-linked immunosorbent assay (HAVAB Abbott) and translated to IU per liter using a World Health Organization standard serum for hepatitis A virus antibody. The results were compared with the results obtained after an intramuscular (i.m.) full dose, i.e. 1,440 EU, at 0 and 6-12 months. As estimated from antibody concentration, 3 lots of 144 EU i.c. with 100% or two lots of 216 EU i.c. with 98% seroconversion results in at least as good early protection as the standard immunization with one lot of 1,440 EU i.m., (79% with our method). Indeed, only two doses of 144 EU vaccine (90% seroconversion) seem to give results comparable to the standard procedure. After the booster dose the median antibody concentration is 1,290 IU/l for the 144 EU vaccine and 837 for the 216 EU one, compared with an antibody response of 990 IU/l for the standard 1,440 EU i.m. vaccination. In conclusion, three doses of 144 EU vaccine i.c. or, as an alternative, two doses of 216 EU at monthly intervals give good early protection (e.g. before travel). After the booster dose, which is given 6 months to 1 year later, the serological response is comparable to the standard procedure of two doses of the 1,440 EU vaccine given i.m. and with 100% seroconversion in all three programs.
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Affiliation(s)
- U Carlsson
- Department of Infectious Diseases, Kalmar Hospital, Sweden
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Abstract
In the past year, interesting new information concerning various aspects of the folding process of beta-sheet proteins has been gleaned. Kinetic and equilibrium folding intermediates have been characterized. Studies of extensively denatured states and of model peptide fragments have enabled important steps to be taken towards an understanding of the initiation of the folding process of beta-sheet proteins. Site-directed mutagenesis has been used in combination with various probes to monitor folding events.
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Affiliation(s)
- U Carlsson
- Department of Chemistry, Linköping University, Sweden
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Svensson M, Jonasson P, Freskgård PO, Jonsson BH, Lindgren M, Mårtensson LG, Gentile M, Borén K, Carlsson U. Mapping the folding intermediate of human carbonic anhydrase II. Probing substructure by chemical reactivity and spin and fluorescence labeling of engineered cysteine residues. Biochemistry 1995; 34:8606-20. [PMID: 7612602 DOI: 10.1021/bi00027a010] [Citation(s) in RCA: 49] [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: 01/26/2023]
Abstract
Several conformation-sensitive parameters have shown that human carbonic anhydrase II exists as a stable and compact equilibrium folding intermediate of molten globule type. In this study we have continued a previously initiated mapping of the intermediate structure. Cys residues were engineered, one at a time, into various regions of the protein structure, so as to obtain chemically reactive probes and handles for spectroscopic probes. These probes were used to specifically report on conformational changes accompanying the folding process. Thus, the accessibility of the introduced Cys residues to specific chemical labeling by radioactive iodoacetate was used to monitor the stability and compactness of the substructure surrounding each Cys residue. In addition, a spin-label (nitroxide radical) and a fluorescent probe (IAEDANS) were attached to the inserted SH-groups to give complementary information. The mobility of the spin-label was used to indicate local changes in structure, and the fluorophore was used to probe local changes in polarity at various stages of unfolding. Much of the predominant beta-structure, consisting of 10 beta-strands extending throughout the entire molecule, appears to be compact and largely intact in the intermediate. Thus, beta-strands 3-7, probed at positions 68, 97, 118, 123, 206, and 245, seem to have a native-like structure in the folding intermediate. In contrast, a more flexible structure is found around positions 56, 176, and 256 in the peripheral beta-strands 1, 2, and 9, showing that the stability of the secondary structure in the intermediate state is less in the outer parts of the protein. A hydrophobic region, containing beta-strands 3-5, seems to be remarkably stable and is not ruptured until strong denaturing conditions (5 M GuHCl) are applied. The stability of this hydrophobic beta-core appears to increase toward the center. This stable region is contained in the middle of a sequentially continuous antiparallel structure that spans beta-strands 2-6, suggesting that this part might represent a site where folding is initiated.
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Affiliation(s)
- M Svensson
- IFM-Department of Chemistry, Linköping University, Sweden
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Lindgren M, Svensson M, Freskgård PO, Carlsson U, Jonasson P, Mårtensson LG, Jonsson BH. Characterization of a folding intermediate of human carbonic anhydrase II: probing local mobility by electron paramagnetic resonance. Biophys J 1995; 69:202-13. [PMID: 7669898 PMCID: PMC1236238 DOI: 10.1016/s0006-3495(95)79892-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The spin-labeling method was used to investigate human carbonic anhydrase, HCA II, undergoing unfolding induced by guanidine-HCI (Gu-HCI). The spin-probe, N-(2,2,5,5-tetramethyl-1-yloxypyrrolidinyl-3-yl)iodoacetamide, was attached covalently to the single cysteine (position 206) in the enzyme. The electron paramagnetic resonance spectrum of the folded structure showed the characteristic slow motional spectra. When the concentration of the denaturing agent, Gu-HCI, was gradually increased, new spectral components with narrower lines evolved to give complex electron paramagnetic resonance spectra, apparently containing superimposed contributions from several components of different mobility. By a differentiation technique, it was possible to follow the relative increase of the narrow components as a function of Gu-HCI concentration. The amplitude of difference spectra versus Gu-HCI concentration showed two distinct maxima, indicating the existence of a folding intermediate state/structure. The results were found to agree with optical absorption data, which showed similar transitions at the same Gu-HCI concentrations. From line-shape simulations assuming a Brownian diffusion model, the rotational diffusion constants for the spin-label in the folded, folding intermediate, and unfolded structures were determined. The relative abundances of the three conformations in the region 0-4 M Gu-HCI were obtained by least squares fitting of the simulated spectra to the experimental ones. The folding intermediate was found to have a maximum population of 39 +/- 4% at approximately 0.7 M Gu-HCI.
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Affiliation(s)
- M Lindgren
- Department of Chemical Physics, Linköping University, Sweden
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Persson M, Aronsson G, Bergenhem N, Freskgård PO, Jonsson BH, Surin BP, Spangfort MD, Carlsson U. GroEL/ES-mediated refolding of human carbonic anhydrase II: role of N-terminal helices as recognition motifs for GroEL. Biochim Biophys Acta 1995; 1247:195-200. [PMID: 7696308 DOI: 10.1016/0167-4838(94)00227-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The presence of GroEL/ES during the refolding of human carbonic anhydrase II (pseudo-wild type) was found to increase the yield of active enzyme from 65 to 100%. This chaperone action on the enzyme could be obtained by adding GroEL alone, and the time-course in that case was only moderately slower than the spontaneous process. Truncated forms of carbonic anhydrase, in which N-terminal helices were removed, also served as protein substrates for GroEL/ES. This demonstrates that N-terminally located helices are not obligatory as recognition motifs.
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Affiliation(s)
- M Persson
- IFM-Department of Chemistry, Linköping University, Sweden
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47
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Paton DJ, Carlsson U, Lowings JP, Sands JJ, Vilcek S, Alenius S. Identification of herd-specific bovine viral diarrhoea virus isolates from infected cattle and sheep. Vet Microbiol 1995; 43:283-94. [PMID: 7785188 DOI: 10.1016/0378-1135(94)00107-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [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: 01/27/2023]
Abstract
Thirteen pestiviruses isolated from ruminants on four different farms in Sweden were compared antigenically and genetically. On two farms, viruses were isolated from both cattle and sheep, a third farm contained only sheep and a fourth only cattle. Seven viruses were isolated from six different cattle and six viruses were isolated from five different sheep. Epitope conservation between the viruses was studied with a panel of 32 monoclonal antibodies, revealing that all of the isolates were BVDV-like. However, certain epitopes present in isolates from cattle were lost following virus transmission to sheep. In vitro amplification of the 5'-untranslated region of the 13 isolates by the polymerase chain reaction (PCR) and subsequent analyses of amplified products with restriction enzymes also indicated that all 13 isolates belong to the BVDV group of pestiviruses. A fragment of the E2 (gp53) gene of each virus was amplified by PCR and a comparison of the amplified sequence of 188 nucleotides separated the isolates into four groups each of which could be identified with a particular farm of origin. The 13 isolates were thus herd-specific rather than species-specific demonstrating that BVDV is readily transmitted between cattle and sheep.
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Affiliation(s)
- D J Paton
- Central Veterinary Laboratory (Weybridge), Addlestone, Surrey, UK
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48
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Abstract
BACKGROUND AND STUDY AIMS A benzodiazepine is generally used when sedation is required for endoscopy, whilst the newer agent propofol appears to have a more suitable pharmacokinetic profile. The aim of this study was to compare the quality of sedation provided by midazolam and propofol under controlled conditions. PATIENTS AND METHODS Ninety healthy outpatients requesting sedation at diagnostic gastroscopy were prospectively randomized to receive a bolus dose of either midazolam 0.06 mg/kg or propofol 0.6 mg/kg, followed by repeat doses of 50% of the initial dose as required. No topical anesthesia was used. The endoscopist and the patient replied to a questionnaire. RESULTS Patients receiving propofol tolerated endoscopy better (p = 0.01); reached a deeper maximum level of sedation (p = 0.001); and recovered more rapidly (p = 0.001). There was a similar frequency of amnesia for the procedure (propofol 67% vs. midazolam 65%); of oxygen desaturation (four patients in each group, < 85%); and of perceived patient comfort (p = 0.5). CONCLUSIONS Compared to midazolam, propofol facilitated gastroscopy to a greater extent. However, due to its narrower therapeutic range, propofol is the more demanding agent to administer, thus making it less universally applicable than midazolam.
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Affiliation(s)
- U Carlsson
- Department of Surgery, General Hospital, Oskarshamn, Sweden
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49
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Abstract
Truncations and mutations in the N-terminus of human carbonic anhydrase II were constructed in order to establish what role this part of the protein plays in the folding and stability of the protein. When incubated in various concentrations of guanidine hydrochloride (GuHCl), HCAII unfolds in two transitions, with an intermediate state at about 1.3 M GuHCl. N-Terminal truncations of 5, 17, or 24 amino acid residues destabilize the native state by 4-5 kcal/mol, relative to the intermediate state, but these amino acid residues have virtually no effect on the stability of the intermediate state relative to the unfolded state. These truncated variants of HCAII still have a high enzymatic activity. Deletion of 28 or more amino acid residues, however, results in inactive enzyme variants. The rates at which the active site is formed are practically unaffected by the removal of the 24-amino acid segment, i.e., the active site forms independently of the N-terminus. By using the tryptophans in positions 5 and 16 as intrinsic probes, we conclude that the structure of the N-terminal region is formed very late in folding. The results strongly indicate that this process is dependent on the prior formation of an enzymatically active native-like structure of the rest of the protein.
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Affiliation(s)
- G Aronsson
- Department of Biochemistry, Umeå University, Sweden
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50
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Mårtensson LG, Jonasson P, Freskgård PO, Svensson M, Carlsson U, Jonsson BH. Contribution of individual tryptophan residues to the fluorescence spectrum of native and denatured forms of human carbonic anhydrase II. Biochemistry 1995; 34:1011-21. [PMID: 7827017 DOI: 10.1021/bi00003a036] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.5] [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: 01/27/2023]
Abstract
Measurements were made of fluorescence spectra produced by pseudo-wild-type human carbonic anhydrase II and mutants in which the tryptophan residues had been replaced by phenylalanine or cysteine residues. 2D NMR spectra of 15N-labeled proteins indicated that the mutations had essentially no long range effects on structure and that the pertubations of structure in the vicinity of the mutated Trp were small. The individual contributions of the seven tryptophan residues were deduced from measurements on native proteins and on proteins subjected to various denaturing conditions. Trp97 and Trp245 are the major fluorescence emitters in the native state, contributing 52% and 38%, respectively, to the total fluorescence intensity. Comparisons of the fluorescence yield of pseudo-wild-type human carbonic anhydrase II and mutant proteins also indicate net energy transfer from Trp16 to Trp5 and from Trp192 to Trp209. The fluorescence from Trp5 is efficiently quenched by His64. In addition, acrylamide quenching of fluorescence was used to probe the environment of tryptophans in proteins incubated in 0, 1.5, and 5 M guanidine hydrochloride. The results indicate that the part of the native protein that corresponds to beta-strands 3-7 forms a compact core in a molten globule intermediate.
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