1
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Abstract
SummaryChromogenic substrates for thrombin with high specificity are necessary for several functional assays, especially for the performance of photometric PT and APTT. A new approach to improve the specificity of chromogenic peptide substrates is made coupling tripeptide sequences selective for thrombin to derivatives of 5-amino-2-nitro benzoic acid (ANBA). Especially when the chromophore’s side chain is substituted by amines or amino acids hydrolysis rates by other enzymes like kallikrein, plasmin or factor Xa are decreased significantly compared to corresponding para-nitroanilides of the same amino acid sequence. On the other hand, most of these compounds are still sensitive thrombin substrates. KM-values for thrombin and other enzymes are in the same order of magnitude as corresponding pNA-peptides. ANBA peptide substrates may be useful to measure thrombin selectively in a mixture of other proteases like plasmin, factor Xa or kallikrein and for the colorimetric determination of PT and APTT.
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Affiliation(s)
- H-J Kolde
- The Research Laboratories of Behringwerke AG, Marburg/Lahn, Fed. Rep. of Germany
| | - R Eberle
- The Research Laboratories of Behringwerke AG, Marburg/Lahn, Fed. Rep. of Germany
| | - H Hebert
- The Research Laboratories of Behringwerke AG, Marburg/Lahn, Fed. Rep. of Germany
| | - N Heimburger
- The Research Laboratories of Behringwerke AG, Marburg/Lahn, Fed. Rep. of Germany
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2
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Meng W, Hebert H, Palmer C. A genome-wide association study suggests that the NADPH Oxidase 4 (NOX4) gene is associated with severe diabetic retinopathy in a Scottish diabetic population. Acta Ophthalmol 2017. [DOI: 10.1111/j.1755-3768.2017.02182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- W. Meng
- Population Health Sciences; University of Dundee; Dundee UK
| | - H. Hebert
- Population Health Sciences; University of Dundee; Dundee UK
| | - C. Palmer
- Centre for Pharmacogenetics and Pharmacogenomics; University of Dundee; Dundee UK
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3
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Nilsson H, Muyo ST, Bäckström M, Thomsson E, Ambort D, Koeck P, Thornton D, Hebert H, Hansson G. WS06.6 The supramolecular packing of the gel-forming MUC5B and MUC2 mucins and its importance for mucus secretion. J Cyst Fibros 2016. [DOI: 10.1016/s1569-1993(16)30095-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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4
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Nilsson H, Ambort D, Bäckström M, Thomsson E, Koeck P, Hebert H, Hansson G. WS12.1 Assembly of MUC2 N-terminal with relevance for mucus formation. J Cyst Fibros 2014. [DOI: 10.1016/s1569-1993(14)60076-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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5
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Nilsson H, Ambort D, Hansson G, Hebert H. 55* Molecular structure, packing and release of MUC2 with relevance to cystic fibrosis. J Cyst Fibros 2011. [DOI: 10.1016/s1569-1993(11)60074-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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6
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Purhonen P, Thomsen K, Maunsbach AB, Hebert H. Association of renal Na,K-ATPase alpha-subunit with the beta- and gamma-subunits based on cryoelectron microscopy. J Membr Biol 2007; 214:139-46. [PMID: 17557166 DOI: 10.1007/s00232-006-0056-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 11/29/2006] [Indexed: 11/28/2022]
Abstract
Na,K-ATPase transports Na(+) and K(+) across cell membranes and consists of alpha- and beta-subunits. Na,K-ATPase also associates with small FXYD proteins that regulate the activity of the pump. We have used cryoelectron microscopy of two-dimensional crystals including data to 8 A resolution to determine the three-dimensional (3-D) structure of renal Na,K-ATPase containing FXYD2, the gamma-subunit. A homology model for the alpha-subunit was calculated from a Ca(2+)-ATPase structure and used to locate the additional beta- and gamma-subunits present in the 3-D map of Na,K-ATPase. Based on the 3-D map, the beta-subunit is located close to transmembrane helices M8 and M10 and the gamma-subunit is adjacent to helices M2 and M9 of the alpha-subunit.
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Affiliation(s)
- P Purhonen
- Department of Biosciences and Nutrition and School of Technology and Health, Karolinska Institutet, Royal Institute of Technology, S-141 57, Huddinge, Sweden
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7
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Holm PJ, Bhakat P, Jegerschöld C, Gyobu N, Mitsuoka K, Fujiyoshi Y, Morgenstern R, Hebert H. Atomic model of microsomal glutathione transferase 1 from electron crystallography. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305096236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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8
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Hebert H, Purhonen P, Vorum H, Thomsen K, Maunsbach AB. Three-dimensional structure of renal Na,K-ATPase from cryo-electron microscopy of two-dimensional crystals. J Mol Biol 2001; 314:479-94. [PMID: 11846561 DOI: 10.1006/jmbi.2001.5137] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [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: 11/22/2022]
Abstract
The structure of Na, K-ATPase was determined by electron crystallography at 9.5 A from multiple small 2-D crystals induced in purified membranes isolated from the outer medulla of pig kidney. The density map shows a protomer stabilized in the E(2) conformation which extends approximately 65 A x 75 A x 150 A in the asymmetric unit of the P2 type unit cell. The alpha, beta, and gamma subunits were demonstrated in the membrane crystals with Western blotting and related to distinct domains in the density map. The alpha subunit corresponds to most of the density in the transmembrane region as well as the large hydrophilic headpiece on the cytoplasmic side of the membrane. The headpiece is divided into three separated domains, which are similar in overall shape to the domains of the calcium pump of the sarcoplasmic reticulum. One of these domains gives rise to a characteristic elongated projection onto the membrane plane while the putative nucleotide binding and phosphorylation domains form comparatively compact densities in the rest of the cytoplasmic part of the structure. Density on the extracellular face corresponds to the protein part of the beta subunit and is located as an extension of the transmembrane region perpendicular to the membrane plane. The structure of the lipid bilayer spanning part suggests the positions for the transmembrane helix from the beta subunit as well as the small gamma subunit present in this Na,K-ATPase. Two groups of ten helices from the catalytic alpha subunit corresponds to the remaining density in the transmembrane region. The present results demonstrate distinct similarities between the structure of the alpha subunit of Na,K-ATPase as determined here by cryo-electron microscopy and the reported X-ray structure of Ca-ATPase. However, conformational changes between the E(1) and E(2) forms are suggested by different relative positions of cytoplasmatic domains.
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Affiliation(s)
- H Hebert
- Karolinska Institutet Department of Biosciences, Center for Structural Biochemistry, Novum, Huddinge, S-141 57, Sweden.
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9
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Abstract
Electron crystallography as a structural determination technique has grown dramatically in use over recent years. Improvements in microscopes, equipment, practical techniques, computation facilities and image processing methods are reflected in the increasing number of near-atomic resolution structures that have been published. In this review we shall summarize the techniques involved in structure determination of soluble proteins using electron crystallography. Many soluble protein structures have been investigated in this manner over the past two decades. Here we present several examples where a variety of approaches have been used to gradually increase the information obtained.
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Affiliation(s)
- M J Ellis
- Center for Structural Biochemistry, Karolinska Institutet, Novum, S-141 57, Huddinge, Sweden
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10
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Schmidt-Krey I, Mitsuoka K, Hirai T, Murata K, Cheng Y, Fujiyoshi Y, Morgenstern R, Hebert H. The three-dimensional map of microsomal glutathione transferase 1 at 6 A resolution. EMBO J 2000; 19:6311-6. [PMID: 11101503 PMCID: PMC305867 DOI: 10.1093/emboj/19.23.6311] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Microsomal glutathione transferase 1 (MGST1) is representative of a superfamily of membrane proteins where different members display distinct or overlapping physiological functions, including detoxication of reactive electrophiles (glutathione transferase), reduction of lipid hydroperoxides (glutathione peroxidase), and production of leukotrienes and prostaglandin E. It follows that members of this superfamily constitute important drug targets regarding asthma, inflammation and the febrile response. Here we propose that this superfamily consists of a new class of membrane proteins built on a common left-handed four-helix bundle motif within the membrane, as determined by electron crystallography of MGST1 at 6 A resolution. Based on the 3D map and biochemical data we discuss a model for the membrane topology. The 3D structure differs significantly from that of soluble glutathione transferases, which display overlapping substrate specificity with MGST1.
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Affiliation(s)
- I Schmidt-Krey
- Karolinska Institutet, Center for Structural Biochemistry, Department of Biosciences, Novum, S-141 57 Huddinge, Germany
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11
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Abstract
The modulation transfer function (MTF) and the geometric errors of two flatbed scanners, a slow-scan CCD (SSC) camera and film, have been measured and compared. The geometric errors of the SSC camera and film have been measured using diffraction spots from a lipid crystal. The SSC camera was shown to have the smallest geometric errors while film had the best MTF. Even though film had the best MTF, this is significantly reduced when scanning the film, so that the MTF of the film and scanner combined are comparable to the MTF of the SSC camera.
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Affiliation(s)
- J Hesse
- Karolinska Institute, Department of Bioscience at Novum, S-14157 Huddinge, Sweden
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12
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Schmidt-Krey I, Murata K, Hirai T, Mitsuoka K, Cheng Y, Morgenstern R, Fujiyoshi Y, Hebert H. The projection structure of the membrane protein microsomal glutathione transferase at 3 A resolution as determined from two-dimensional hexagonal crystals. J Mol Biol 1999; 288:243-53. [PMID: 10329140 DOI: 10.1006/jmbi.1999.2683] [Citation(s) in RCA: 30] [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: 11/22/2022]
Abstract
The formation of two-dimensional crystals of the membrane-bound enzyme microsomal glutathione transferase is sensitive to fractional changes in the lipid-to-protein ratio. Variation of this parameter results in crystal polymorphism. The projection structure of a p6 crystal form of the enzyme has been determined by the use of electron crystallography. The unit cell at 3 A resolution is comprised of two trimers. The hexagonal p6 and the orthorhombic p21212 crystal types have common elements in the packing arrangement which imply dominant crystal contacts. An overall structural similarity between the protein molecules in the two crystal forms is suggested by the projection maps. Furthermore, a comparison of the p6 and p21212 projection maps identifies additional corresponding protein densities which could not be assigned to the microsomal glutathione transferase trimer previously. Surprisingly, an ambiguity of the rotational orientation was found for trimers interspersed at certain positions within the crystal lattice.
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Affiliation(s)
- I Schmidt-Krey
- Center for Structural Biochemistry, Department of Biosciences, Karolinska Institutet, Huddinge, S-141 57, Sweden.
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13
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Koeck PJ, Kagawa HK, Ellis MJ, Hebert H, Trent JD. Two-dimensional crystals of reconstituted beta-subunits of the chaperonin TF55 from Sulfolobus shibatae. Biochim Biophys Acta 1998; 1429:40-4. [PMID: 9920382 DOI: 10.1016/s0167-4838(98)00218-0] [Citation(s) in RCA: 15] [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] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We have obtained 2-dimensional crystals of the beta-subunits of the chaperonin TF55 from Sulfolobus shibatae reconstituted into oligomers in the absence of alpha-subunits. The subunits form rings with 9-fold rotational symmetry which arrange themselves in a trigonal lattice. From electron micrographs of negatively stained specimens we have calculated a projection map in plane group p312 showing the rings in top-view.
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Affiliation(s)
- P J Koeck
- Karolinska Institute, Department of Bioscience at Novum, Huddinge, Sweden.
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14
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Schmidt-Krey I, Lundqvist G, Morgenstern R, Hebert H. Parameters for the two-dimensional crystallization of the membrane protein microsomal glutathione transferase. J Struct Biol 1998; 123:87-96. [PMID: 9843664 DOI: 10.1006/jsbi.1998.4018] [Citation(s) in RCA: 25] [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: 11/22/2022]
Abstract
Various crystallization parameters were investigated to obtain two-dimensional crystals of the detoxification enzyme microsomal glutathione transferase for structural analysis by electron crystallography. The protein was crystallized by reconstitution of the solubilized trimer into proteoliposomes. Crystallization occurs when minimal amounts of lipid in the range of three lipid molecules per protein trimer are added to the dialysate. Once crystals were obtained, the effect of several parameters on the crystallization was determined. The temperature and initial detergent concentration were found to be crucial parameters in influencing the size of the crystals, and conclusions could be drawn about the rate dependence of the crystallization process. Two highly ordered crystal forms, which are suitable for structural analysis by electron crystallography, were obtained under the two-dimensional crystallization conditions described here.
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Affiliation(s)
- I Schmidt-Krey
- Department of Biosciences, Karolinska Institutet, Huddinge, S-141 57, Sweden
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15
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Ellis MJ, Knapp S, Koeck PJ, Fakoor-Biniaz Z, Ladenstein R, Hebert H. Two-dimensional crystallization of the chaperonin TF55 from the hyperthermophilic archaeon Sulfolobus solfataricus. J Struct Biol 1998; 123:30-6. [PMID: 9774542 DOI: 10.1006/jsbi.1998.4002] [Citation(s) in RCA: 24] [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: 11/22/2022]
Abstract
Oligomers of the chaperonin TF55 from Sulfolobus solfataricus have been successfully crystallized in two dimensions via their interaction with a phospholipid monolayer at the air/liquid interface. Oligomer orientation was dependent upon the lipid headgroup used. A neutral lipid monolayer gave rise to small paracrystalline areas of TF55 side views, whereas a negatively charged lipid monolayer resulted in large coherent crystalline areas of the chaperonin in an end-on orientation. These 2D crystals had p312 symmetry (a = b = 162 A, gamma = 60 degrees). Two-dimensional projection structures of the end-on arrays were produced by electron microscopy and image processing techniques. Under the conditions used to grow the crystals, the protein formed complexes of two stacked nine-subunit rings with threefold symmetry.
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Affiliation(s)
- M J Ellis
- Department of Biosciences, Karolinska Institutet, Huddinge, S-141 57, Sweden.
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16
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Hebert H, Schmidt-Krey I, Morgenstern R, Murata K, Hirai T, Mitsuoka K, Fujiyoshi Y. The 3.0 A projection structure of microsomal glutathione transferase as determined by electron crystallography of p 21212 two-dimensional crystals. J Mol Biol 1997; 271:751-8. [PMID: 9299324 DOI: 10.1006/jmbi.1997.1216] [Citation(s) in RCA: 38] [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
Two-dimensional crystals of rat microsomal glutathione transferase were grown during dialysis of detergent-solubilized enzyme after addition of a small amount of phospholipid. The crystals had two-sided plane group symmetry p21212 with a calibrated unit cell size of a=91.90 A, b=90.83 A. Electron diffraction patterns were recorded showing significant reflections extending to 3.0 A. A combination of these structure factor amplitudes with phases from high-resolution images following image processing was used to calculate a projection map of the protein. The asymmetric unit of the structure consists of three microsomal glutathione transferase molecules. The local 3-fold axis at the center of the trimer is delineated by six parallel alpha-helices, two from each monomer. The two helices differ significantly in their respective projection structure. The inner helical core of the trimer is partly surrounded by elongated domains with extensions towards the helices and which contain resolved density maxima at a spacing of 4 to 5 A. A well-defined strong peak is localized close to the elongated domain and at a distance of about 9.5 A from two of the inner helices.
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Affiliation(s)
- H Hebert
- Department of Biosciences, Karolinska Institutet, Huddinge, S-141 57, Sweden
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17
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Ellis MJ, Hebert H, Thelestam M. Staphylococcus aureus alpha-toxin: characterization of protein/lipid interactions, 2D crystallization on lipid monolayers, and 3D structure. J Struct Biol 1997; 118:178-88. [PMID: 9169228 DOI: 10.1006/jsbi.1997.3849] [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: 02/04/2023]
Abstract
Staphylococcus aureus alpha-toxin was characterized with respect to surface activity and its interaction with lipid monolayers. The protein alone had a detergent-like behavior at the air/water interface. Its affinity was higher for negatively charged than for neutral phospholipids. The interaction was pH dependent, showing a maximum increase at pH 7.0. Only a small part of the protein oligomer appeared to be inserted into the monolayers. Crystalline sheets of alpha-toxin were formed using negatively charged phospholipids. Electron microscopy of such areas, at different tilt angles, allowed reconstruction of a three-dimensional model following image processing. The sheets analyzed consisted of two protein layers arranged on a tetragonal lattice. Under the conditions used to grow the crystals the toxin formed 90-A-wide cylinders with a height of 70 A. One of the imposed fourfold axes running perpendicular to the plane of the crystalline layer is positioned at a protein-deficient region which forms a 25-A-wide pore through the oligomer.
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Affiliation(s)
- M J Ellis
- Centre for Structural Biochemistry, Karolinska Institutet, Huddinge, Sweden.
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18
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Abstract
A low-resolution three-dimensional model of membrane-bound H,K-ATPase from pig gastric mucosa has been reconstructed by electron microscopy and image processing of two-dimensional crystals in negative stain. The crystal formation is induced by magnesium and vanadate, which stabilize the E2 conformation of the enzyme. The unit cell, with a size of a = b = 123 A, gamma = 90 degrees, has tetragonal p4 symmetry. There are four separate alpha beta protomers within each unit cell. The high-contrast region is limited to the cytoplasmic part of the protein. The total volume of the observed asymmetric protein domain corresponds to a molecular mass of 80-90 kDa. It consists mainly of a large pear-shaped domain measuring 60 x 45 A2, with a height of 50 A as measured perpendicular to the membrane plane. A small stalk segment, 20 A in length, forms a connection to the transmembrane region.
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Affiliation(s)
- Y Xian
- Department of Biosciences at Novum, Karolinska Institutet, Huddinge, Sweden
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19
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Abstract
Through the use of electron crystallography, it has been possible to obtain high resolution structural information regarding a mammalian protein that spans the lipid bilayer. Two-dimensional crystals of the detoxification enzyme microsomal glutathione transferase were induced by slow detergent removal from a mixture containing low amounts of phospholipid. Images of specimens stabilized in tannin were collected using electron cryomicroscopy. The projection structure at 4 A shows tightly packed trimers of the protein. Each of them contains an inner core of six parallel alpha-helices delineating a central low density region. The helical bundle is partly surrounded by elongated domains.
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Affiliation(s)
- H Hebert
- Center for Structural Biochemistry, Karolinska Institutet, Novum, Huddinge, Sweden
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20
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Knapp S, Schmidt-Krey I, Hebert H, Bergman T, Jörnvall H, Ladenstein R. The molecular chaperonin TF55 from the Thermophilic archaeon Sulfolobus solfataricus. A biochemical and structural characterization. J Mol Biol 1994; 242:397-407. [PMID: 7932699 DOI: 10.1006/jmbi.1994.1590] [Citation(s) in RCA: 21] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The purification and characterization of a new type of thermostable chaperonin from the archaebacterium Sulfolobus solfataricus is described. The chaperonin forms a hetero-oligomeric complex of two different, but closely related, subunits, which we have assigned TF55-alpha and TF55-beta. Their N-terminal sequences and amino acid residue compositions are reported. Two-dimensional projections of the chaperonin have been reconstructed from electron microscopy images, showing a 9-fold symmetrical complex, about 17.5 nm in height and 16 nm in diameter, with a central cavity of 4.5 nm. The complex is resistant to denaturing agents at room temperature and only pH values lower than 2 lead to dissociation. The separated subunits do not reassemble spontaneously but require Mg2+ and ATP for complex formation. Both subunits are necessary for formation of the TF55 oligomer. Significant structural changes have been observed after phosphorylation, thus providing evidence for a structural mobility during the chaperonin-assisted folding process of a protein. The phosphorylation reaction is modulated by potassium and magnesium ions. Magnesium seems to have an inhibitory effect, whereas potassium enhances this reaction.
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Affiliation(s)
- S Knapp
- Karolinska Institutet, NOVUM, Center for Structural Biochemistry, Huddinge, Sweden
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21
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Abstract
The cytolysin Perfringolysin O was applied to lipid layers and the obtained ring-shaped oligomers analyzed by electron microscopy and image processing. The final result shows the periodic repeat of 2.4 nm along the outer rim of the ring. The asymmetric protein unit, corresponding to one monomer, spans the ring from the convex to the concave surface. It shows a clear protein peak close to the outer radius and less density in the middle of the oligomer. The number of monomers in the average ring is 50, and the inner radius of the aggregate is approximately 15 nm.
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Affiliation(s)
- A Olofsson
- Center for Structural Biochemistry, Karolinska Institutet, NOVUM, Huddinge, Sweden
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22
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Hebert H, Olofsson A, Thelestam M, Skriver E. Oligomer formation of staphylococcal alpha-toxin analyzed by electron microscopy and image processing. FEMS Microbiol Immunol 1992; 5:5-12. [PMID: 1419115 DOI: 10.1111/j.1574-6968.1992.tb05880.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The 12S oligomeric form of Staphylococcus aureus alpha-toxin has been studied with electron microscopy after incubation of the toxin with membrane preparations or liposomes. The target material originated from human platelets. Different electron microscopic preparation techniques were used including negative staining, freeze-fracture and vitrification in liquid ethane. Analysis of micrographs with image processing methods revealed two groups of ring-like structures corresponding to alpha-toxin oligomers. One form measured 75 A in diameter and had a high stain density in the central protein deficient part while the other was larger with a diameter of 100 A and less stain accumulation in the center. The conditions under which the latter were formed suggest that this corresponds to an inactive loosely-bound form of the toxin. The high stain density in the smaller particle is consistent with the presence of a penetrating pore in this structure.
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Affiliation(s)
- H Hebert
- Center for Structural Biochemistry, Karolinska Institutet, NOVUM, Huddinge, Sweden
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23
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Hebert H. Oligomer formation of staphylococcal α-toxin analyzed by electron microscopy and image processing. FEMS Microbiol Lett 1992. [DOI: 10.1016/0378-1097(92)90069-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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24
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Abstract
Trypsin treatment of staphylococcal alpha-toxin cleaves the molecule into two roughly equally sized parts, which results in inactivation of the toxin. Tetragonal arrays of oligomers, closely resembling the native ones, can however be formed on lipid layers. From tilted views of negatively stained crystals a 3D structure to 23 A resolution has been determined by electron microscopy and image processing. On comparison with the 3D structure of the native alpha-toxin (Olofsson et al., J. Mol. Biol. 214, 299-306, 1990) the subdomains are more separated, confirming the differences found when comparing the projection maps (Olofsson et al., J. Struct. Biol. 106, 199-204, 1991). The tryptic cleavage takes place in a postulated hinge region. The results are consistent with the hypothesis that the conformational change required for inducing the membrane permeabilizing property takes place in this region. Furthermore, we present a refined projection map at approximately 10 A resolution based on the analysis of a large number of crystals using unbending methods.
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Affiliation(s)
- A Olofsson
- Center for Structural Biochemistry, Karolinska Institutet, Huddinge, Sweden
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25
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Abstract
Two-dimensional crystallization of membrane-bound H,K-ATPase (EC 3.6.1.36) in vesicle preparations from parietal cells of hog gastric mucosa was induced by an imidazole buffer containing Mg2+ and VO3- ions. A continuous reorganization of the protein molecules started within a few hours by the formation of linear arrays. At later stages confluent two-dimensional crystals were formed. Electron microscopy and image processing showed that these were of a single tetragonal type. The asymmetric unit consisted of one pear-shaped protein domain corresponding to a H,K-ATPase protomer. Through stain-deficient contact regions four adjacent protein units were connected forming a tetrameric structure.
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Affiliation(s)
- H Hebert
- Center for Structural Biochemistry, Karolinska Institute, Novum, Huddinge, Sweden
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26
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Skriver E, Kavéus U, Hebert H, Maunsbach AB. Three-dimensional structure of Na,K-ATPase determined from membrane crystals induced by cobalt-tetrammine-ATP. J Struct Biol 1992; 108:176-85. [PMID: 1336671 DOI: 10.1016/1047-8477(92)90017-5] [Citation(s) in RCA: 17] [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: 12/26/2022]
Abstract
The three-dimensional structure of Na,K-ATPase has been analyzed with electron microscopy and image processing. The enzyme, purified from pig kidney outer medulla, was arranged in a new form of tetragonal two-dimensional membrane crystals after incubation with cobalt-tetrammine-ATP, a stable MgATP complex analogue. Each continuous protein domain, as delineated by negative stain, consists of two alpha beta-protomers related by a dyad axis. The two rod-like regions are connected by a bridge displaced about 20 A away from the center of the structure toward the lipid bilayer. The domain connecting the two promoters is more constricted and closer to the center of the structure in the Co(NH3)4ATP-induced crystals than in the vanadate-induced p21 crystals. These observations suggest that the difference between previously analyzed dimers of two-dimensional p21 crystals induced with vanadate/magnesium and dimers of p4 crystals induced with Co(NH3)4ATP reflects two different conformational states of the enzyme.
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Affiliation(s)
- E Skriver
- Department of Cell Biology, University of Aarhus, Denmark
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Abstract
Staphylococcus aureus alpha-toxin was treated with trypsin, which inactivates the toxin. Two-dimensional crystals of the modified protein were produced on preformed lipid layers. The projection structure obtained by electron crystallographic analysis of a large number of crystals showed tetragonal p4 symmetry and a resolution of approximately 12 A. The fragments of the toxin, 17 and 18 kDa large, were arranged in a way resembling those observed earlier for the native protein (Olofsson et al., J. Mol. Biol. 214, 299-306, 1990). However, after trypsin treatment the stain-deficient region corresponding to one alpha-toxin monomer shows two separated subdomains of similar size. This separation is probably related to the inability of the modified toxin to undergo the conformational change thought to be essential for the membrane-damaging effect.
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Affiliation(s)
- A Olofsson
- Center for Structural Biochemistry, Karolinska Institutet, Huddinge, Sweden
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Thelestam M, Olofsson A, Blomqvist L, Hebert H. Oligomerisation of cell-bound staphylococcal alpha-toxin in relation to membrane permeabilisation. Biochim Biophys Acta 1991; 1062:245-54. [PMID: 2004111 DOI: 10.1016/0005-2736(91)90399-s] [Citation(s) in RCA: 22] [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: 12/29/2022]
Abstract
We have studied the kinetics of staphylococcal alpha-toxin oligomerisation in relation to membrane permeabilisation, using as targets cultured adrenocortical Y1 cells, rabbit red blood cells (RRBC), human platelets, and liposomes prepared of lipids extracted from platelets. After isolation of membranes from toxin-treated cells, oligomeric toxin was detected (i) by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) followed by autoradiography or Western blotting, and (ii) by electron microscopy of negatively stained specimens. alpha-Toxin was found to oligomerise on all membranes independently of the temperature. On RRBC and Y1 cells most of the membrane associated toxin appeared converted to the oligomeric form. Hexamers were always present along with membrane permeabilisation. However, hexamers were also detected at conditions when membrane permeabilisation did not occur; at low temperature, in the presence of high concentrations of Ca2+, and after pretreatment of cells with concanavalin A (Con A). Addition of a neutralising monoclonal antibody (MAb) to cell-bound toxin collected it into aggregates much larger than the hexamers. By contrast hexameric toxin remained after addition of a non-neutralising MAb. Our data suggest that the active toxin species is not monomeric, and support the hypothesis that alpha-toxin permeabilises membranes by forming hexameric protein-lined transmembrane channels.
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Affiliation(s)
- M Thelestam
- Department of Bacteriology, Karolinska Institutet, Stockholm, Sweden
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Abstract
Two-dimensional membrane crystals of renal Na,K-ATPase were analyzed by electron microscopy and image processing. The particular property of the crystals in this work was that they showed unit cell parameters similar to the previously studied p21 crystals but lacked the dyad axis as observed in nominal 0 degrees-projections. A three-dimensional reconstruction revealed that structural differences between alpha beta-units of the enzyme gave rise to the asymmetry. A high degree of two-fold rotational symmetry was observed in the middle of the structure while the protein units had different three-dimensional shapes at levels above and below the central sections. The simultaneous coexistence of different forms of Na,K-ATPase suggests that the conformational flexibility of the enzyme plays an important role in the pumping process.
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Affiliation(s)
- H Hebert
- Department of Medical Biophysics, Karolinska Institutet, Stockholm, Sweden
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Abstract
Interaction of the pore-forming protein alpha-toxin from Staphylococcus aureus with lipid components from platelet membranes induces crystal formation of the toxin oligomers. Structure analysis of crystalline areas in either sodium phosphotungstic acid or a sodium phosphotungstic acid/glucose mixture has been performed with electron microscopy and image processing. Ordered domains extending up to a few micrometers were observed, particularly after application of alpha-toxin to pre-formed lipid layers. The crystals, showing tetragonal symmetry, formed either separate two-dimensional sheets or three-dimensional piles of layers. The corresponding unit cell parameter of the single layer was a = b = 109.4 A (standard deviation 2.1 A, n = 21). Incubation of the toxin with intact membranes or extracted lipids as well as application of the lipid layer technique resulted in congruous crystalline properties. The projected averaged alpha-toxin oligomer shows cyclic symmetry with a stain-filled space in the centre. The bulk of the three-dimensional model consists of four asymmetric protein units forming a ring. In addition, a small domain covers the central cavity at the face of the protein opposite to the underlying lipid. The conditions under which the tetragonal arrays are formed on the lipid layers suggest that the alpha-toxin molecule is in a conformation binding to a hydrophobic surface rather than fully inserted into a lipid bilayer.
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Affiliation(s)
- A Olofsson
- Department of Medical Biophysics, Karolinska Institutet, Stockholm, Sweden
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Skriver E, Maunsbach AB, Hebert H, Scheiner-Bobis G, Schoner W. Two-dimensional crystalline arrays of Na,K-ATPase with new subunit interactions induced by cobalt-tetrammine-ATP. J Ultrastruct Mol Struct Res 1989; 102:189-95. [PMID: 2561364 DOI: 10.1016/0889-1605(89)90013-x] [Citation(s) in RCA: 23] [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: 01/01/2023]
Abstract
Purified membrane-bound Na,K-ATPase incubated with cobalt-tetrammine-ATP [Co(NH3)4ATP], which is a stable MgATP complex analog, shows two new types of membrane crystals, a new p21 form and a p4 form. The building blocks of the crystalline arrays correspond to (alpha beta)2 dimers of the enzyme protein suggesting that alpha-alpha interaction may be important in the pumping process.
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Affiliation(s)
- E Skriver
- Department of Cell Biology, University of Aarhus, Denmark
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Olofsson A, Kavéus U, Thelestam M, Hebert H. The projection structure of alpha-toxin from Staphylococcus aureus in human platelet membranes as analyzed by electron microscopy and image processing. J Ultrastruct Mol Struct Res 1988; 100:194-200. [PMID: 3225479 DOI: 10.1016/0889-1605(88)90026-2] [Citation(s) in RCA: 24] [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: 01/04/2023]
Abstract
Most strains of Staphylococcus aureus produce alpha-toxin, a 33-kDa membrane active protein which is considered to be an important virulence factor of this bacterium. When alpha-toxin interacts with membranes an oligomeric from of the toxin can be seen by electron microscopy as characteristic ring structures in the membrane. A two-dimensional study of these annular structures, incorporated in membranes of human platelets, was performed, introducing a partly new method for rotational alignment of individual particles. It is shown that the averaged oligomer consists of six subunits. At neutral pH the outer diameter of the ring is about 75 A. The stain-filled pore or cavity in the center has a diameter of about 25 A. The size of the hexamer is increased if the pH is lowered.
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Affiliation(s)
- A Olofsson
- Department of Medical Biophysics, Karolinska Institutet, Stockholm, Sweden
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Hebert H, Skriver E, Söderholm M, Maunsbach AB. Three-dimensional structure of renal Na,K-ATPase determined from two-dimensional membrane crystals of the p1 form. J Ultrastruct Mol Struct Res 1988; 100:86-93. [PMID: 2850317 DOI: 10.1016/0889-1605(88)90061-4] [Citation(s) in RCA: 15] [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] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Electron microscopy and image processing were used to reconstruct a three-dimensional model of membrane-bound monomeric renal Na,K-ATPase from negatively stained two-dimensional crystals of the p1 type. Correlation methods were applied to obtain projection averages which were aligned by a phase difference minimization procedure. The self-consistency of the reconstruction process was high as determined by correlation between experimental projections and projections of the calculated model. The three-dimensional model of the Na,K-ATPase promoter in the p1 crystal form contains three characteristic domains, a protein dense ellipsoid, a small globular stain deficient domain, and a connecting low-contrast region. The latter is thought to correspond to the lipid-penetrating part of the Na,K-ATPase promoter. The location of this domain gives the protein an asymmetric distribution in the bilayer so that it is exposed primarily on one side proposed to correspond to the intracellular face.
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Affiliation(s)
- H Hebert
- Department of Cell Biology, University of Aarhus, Denmark
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Abstract
The assembly of vanadate-induced two-dimensional membrane crystals of Na,K-ATPase was analyzed by electron microscopy and image processing. Electron micrographs of negatively stained linear arrays of protein molecules were recorded and processed by correlation averaging methods. The arrays were compared with fully developed p21 crystals of the enzyme. On the basis of similarity in protein form, symmetry, and packing arrangement it was concluded that the fully developed crystals are built of tightly packed ribbons. Assembly pathways for two-dimensional membrane crystals of Na,K-ATPase are proposed.
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Affiliation(s)
- M Söderholm
- Department of Medical Biophysics, Karolinska Institutet, Stockholm, Sweden
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Olofsson A, Kavéus U, Hebert H. Digitization of electron micrographs: a comparison of three different types of scanners. J Electron Microsc Tech 1988; 8:381-8. [PMID: 3199222 DOI: 10.1002/jemt.1060080407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Some aspects of digitization of electron micrographs have been investigated. The performances of a flat-bed, a rotating drum, and a diode array scanner have been evaluated. Estimates have been achieved for resolution, mechanical and optical stability, and optical density response. It is concluded that for routine transmission electron microscopy of, for example, negatively stained biologic specimens, a diode array scanner produces data good enough to obtain resolutions at a level normally expected. High speed is the major advantage with this type of equipment. However, for high-resolution work it is necessary to use a conventional scanner with a relatively slow scan speed.
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Affiliation(s)
- A Olofsson
- Department of Medical Biophysics, Karolinska Institutet, Stockholm, Sweden
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Abstract
Human fibrinogen was observed by electron microscopy following rotary shadowing with tungsten. Structure analysis of the molecules was performed by image processing of electron micrographs. A method is described for selection, alignment, and classification of molecules. The widely accepted overall trinodular structure of the protein was observed. The flexibility about the central domain of the molecule was quantitatively analyzed. A Gaussian distribution of this conformational parameter was obtained having an average corresponding to a maximally extended structure. Correspondence analysis applied to the aligned images showed that the degree of folding of the molecule was continuously distributed. The averaged structure of fibrinogen was estimated to be 450 A long. The central domain had a diameter of 50 A and the peripheral domains were 90 A long and 50 A wide. The latter regions had two separated maxima of scattering density.
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Affiliation(s)
- L Beijbom
- Department of Medical Biophysics, Karolinska Institutet, Stockholm, Sweden
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Hebert H, Skriver E, Hegerl R, Maunsbach AB. Structure of two-dimensional crystals of membrane-bound Na,K-ATPase as analyzed by correlation averaging. J Ultrastruct Res 1985; 92:28-35. [PMID: 3007778 DOI: 10.1016/0889-1605(85)90124-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The structure of two-dimensional crystals of membrane-bound Na,K-ATPase from rabbit kidney has been analyzed with a correlation averaging procedure. Two principally different crystal forms are observed with p1 and p21 symmetry, respectively. In the p1 form the averaged projection structure shows a triangular shaped protein domain interpreted as a protomer (alpha beta-unit) of Na,K-ATPase. In the p21-form the stain-deficient area is extended toward a twofold symmetry axis. The results are in good agreement with a previous analysis where Fourier methods were applied to well ordered crystals of pig kidney Na,K-ATPase and illustrate that the correlation averaging procedure can be used for the analysis of membrane crystals of Na,K-ATPase showing curved lattice lines.
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Turpin F, Le Doussal V, Floiras JL, Tubiana-Hulin M, Lemoine F, Hebert H, Clavel B. [Metastatic malignant thymoma]. Presse Med 1984; 13:2189-92. [PMID: 6239155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Three cases of metastatic malignant thymoma are reported. In all three cases the tumour was invasive and excision was only partial or impossible. Histologically, these tumours were of epithelial origin with a variable lymphocytic component. Metastases were initially present in one case and in the other two developed within the first year. Partial remission was obtained with different drug combinations in only one case, and it was of short duration. The authors emphasize the increased frequency and poor prognosis of these tumours and the need for multiple chemotherapy and loco-regional treatment in the management of invasive thymomas.
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Hacene K, Le Doussal V, Brunet M, Lemoine F, Guerin P, Hebert H. Prognostic index for clinical Stage I cutaneous malignant melanoma. Cancer Res 1983; 43:2991-6. [PMID: 6850610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Thirteen variables were evaluated for their significance in predicting the survival of 148 patients in a retrospective study with clinical Stage I cutaneous malignant melanoma. The variables studied were histological type, tumor thickness, level of invasion, mitotic activity, pigmentation type, existence of ulceration, presence of lymphocytic infiltration, cell type, sex and age of the patient, site of melanoma, and wide local excision preceded or not by contact radiotherapy and associated or not with lymphadenectomy. When these variables were individualized, only seven were significantly related to survival: histological type; tumor thickness; level of invasion; mitotic activity; pigmentation type; existence of ulceration; and sex of the patient. Multivariate analysis based on Breslow's version of the Cox proportional-hazards model was performed on a group of 110 patients. This analysis demonstrated that 5 of the original 13 variables (i.e., mitotic activity, tumor thickness, sex, lymphadenectomy, and site of primary melanoma) could be used to develop a prognostic model. A Gompertz distribution which provided for an appropriate smoothing of the Breslow model estimates was used to derive a simple prognostic index and to predict the survival of individual patients. Fifty-four patients in a prospective study were subsequently evaluated with the Gompertz model in order to test the prognostic accuracy of the model for the five variables.
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Jørgensen PL, Skriver E, Hebert H, Maunsbach AB. Structure of the Na,K pump: crystallization of pure membrane-bound Na,K-ATPase and identification of functional domains of the alpha-subunit. Ann N Y Acad Sci 1982; 402:207-25. [PMID: 6301331 DOI: 10.1111/j.1749-6632.1982.tb25743.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Abstract
Extensive formation of two-dimensional crystals of the proteins of the pure membrane-bound (Na+ +K+)-ATPase is induced during prolonged incubation with vanadate and magnesium. Some membrane crystals are formed in medium containing magnesium and phosphate. Computer-averaged images of the two-dimensional crystals show that the unit cell in vanadate-induced crystals contains a protomeric alpha beta-unit of the enzyme protein. In phosphate-induced crystals an (alpha beta) 2-unit occupies one unit cell suggesting the interactions between alpha beta-units can be of importance in the function of the Na+, K+ pump.
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Hebert H, Lindberg M. Granules in basophil leukocytes from guinea pig dermis and granules isolated from basophil leukocytes in guinea pig blood and bone marrow: a structural study by electron microscopy and optical diffraction. J Ultrastruct Res 1982; 78:215-25. [PMID: 7086935 DOI: 10.1016/s0022-5320(82)80025-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Le Doussal V, Hebert H. [Ultrastructural examination in tumoral breast pathology]. Arch Anat Cytol Pathol 1982; 30:135-139. [PMID: 7138096] [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: 05/21/2023]
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Le Doussal V, Brunet M, Guérin P, Hacene K, Lasry S, Marcotorchino F, Michaud P, Hebert H, Gest J. [Prognostic histopathological features of malignant melanoma. New statistical approaches (author's transl)]. Nouv Presse Med 1981; 10:2561-3. [PMID: 7279632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The records of 203 patients with cutaneous malignant melanoma treated at the Centre René Huguenin, Saint-Cloud, from october, 1959 to december, 1978 were reviewed. Histological data from 155 patients were retained after re-examination. The melanomas, which had previously been classified according to Clark's system of histological type and degree of invasiveness, were re-evaluated according to the thickness, were re-evaluated according to the thickness of the tumour as measured by Breslow's ocular micrometric method. Other histological data, as well as clinical and therapeutic data, were gathered together. One hundred and fifty cases were found to be suitable for standard single and multifactorial analysis, and 96 records contained sufficient information to be analyzed by the new "similarly aggregation" method developed by IBM. Two significant results emerged from the study: the thickness of the tumor is the single most important prognostic factor, as it correlates with the incidence of recurrences, metastases and deaths; by using a small number of clinical and histological variables, it seems possible to draw a profile of every new patient, to classify him in a well-determined prognostic category and, consequently, to institute a complementary treatment when needed.
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Hebert H. The crystal structure of phenylpropanolamine hydrochloride (2-amino-1-phenyl-1-propanol hydrochloride). Acta Crystallogr B Struct Sci 1979. [DOI: 10.1107/s056774087900844x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
At the end of the last century it was established that the different nerve cells along a neuronal path do not come into direct physical contact with one another, but that there are narrow gaps between them, called synapses (Sherrington, 1897; Ramón y Cajal, 1906). Elliot (1905) made the basic experimental observation that the propagation of nerve impulses across a synapse might be mediated by specific chemical agents (see Fig. i). Such substances are now called neurotransmitters, and some 20 different compounds putatively responsible for synaptic transmission in different parts of the nervous system are known at present, e.g. a few recently isolated polypeptides. The most extensively studied transmitters are acetylcholine and the catecholamine group, consisting of dopamine (a), noradrenaline (b), and adrenaline (c).
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