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Biomedical subjects

W F Beyer

Publications and source records attributed to W F Beyer.

At least 19 recordsLinked to original sources
PubMed2001

[Conservative nonpharmacological treatment of arthrosis].

There are different options for nonpharmacological therapies in osteoarthritis. An educational program and instruction of the patient are of major importance. There is evidence that manual physical therapy and exercise improve function and reduce pain in osteoarthritic joints. Thermal modalities are employed for short-term pain relief and change the intra-articular temperature. Electrotherapy, ultrasound, balneotherapy, and acupuncture show positive therapeutic effects. Orthotics, braces, and wedged insoles may be beneficial in selected cases. Based on the present findings, further investigations are needed to prove the effectiveness of various methods in physical therapy and nonpharmacological approaches to the management of osteoarthritis.

Exercise Therapy↗
PubMed2001

[Outcome measurement in musculoskeletal diseases: recommendation for a core set of scales for use in rehabilitation].

By application of a standardized core set of outcome measurement instruments, comparison between studies as well as meta-analyses in rehabilitation research can be facilitated. The German Society for Rheumatology has commissioned its working group on rehabilitation with the development of a proposal for such a core set of outcome measurement instruments. In a first step, dimensions for outcome measurement in rehabilitation were defined by a group of experts which represented rehabilitation hospitals, acute care hospitals, and research groups specialized in outcome measurement. The Delphi method was used in a multiple step consensus process. In a second step, instruments and procedures to operationalize the relevant dimensions were chosen. Reliability, validity, sensitivity to change, and practicability were used as criteria for selecting measurement instruments. The main intention of the proposed core set of outcome measurement instruments is to facilitate the processes of planning and carrying out rehabilitation research studies. Furthermore, the proposed instruments can be used for clinical documentation systems as well as for internal or external quality assurance programs.

Arthritis, Rheumatoid↗
PubMed2000

Bivalency and epitope specificity of a high-affinity IgG3 monoclonal antibody to the Streptococcus group A carbohydrate antigen. Molecular modeling of a Fv fragment.

The binding of Strep 9, a mouse monoclonal antibody (mAb) of the IgG3 subclass directed against the cell-wall polysaccharide of Group A Streptococcus (GAS), has been characterized. The intact antibody and proteolytic fragments of Strep 9 bind differently to GAS: the intact mAb and F(ab)2' have greater affinity for the carbohydrate epitope than the monomeric Fab or F(ab)'. A mode of binding in which Strep 9 binds bivalently to portions of the polysaccharide on adjacent chains on GAS is proposed. A competitive ELISA protocol using a panel of carbohydrate inhibitors shows that the branched trisaccharide, beta-D-GlcpNAc-(1-->3)-[alpha-L-Rhap-(1-->2)]-alpha-L-Rhap, and an extended surface are key components of the epitope recognized by Strep 9. Microcalorimetry measurements with the mAb and two synthetic haptens, a tetrasaccharide and a hexasaccharide, show enthalpy-entropy compensation as seen in other oligosaccharide-protein interactions. Molecular modeling of the antibody variable region by homology modeling techniques indicates a groove-shaped combining site that can readily accommodate extended surfaces. Visual docking of an oligosaccharide corresponding to the cell-wall polysaccharide into the site provides a putative model for the complex, in which a heptasaccharide unit occupies the site and the GlcpNAc residues of two adjacent branched trisaccharide units occupy binding pockets within the groove-shaped binding site.

Amino Acid Sequence↗
PubMed1996

Purification and characterization of the Cu,Zn SOD from Escherichia coli.

The periplasmic Cu,Zn superoxide dismutase has been purified to homogeneity by a procedure, which depended upon osmotic shock followed by two chromatographic columns. Its subunit weight, determined by electrospray ionization mass spectrometry, was found to be 15,737 +/- 1.6. The second derivative ultraviolet spectrum indicated a lack of tryptophan. The amino acid composition as well as a partial N-terminal amino acid sequence is reported. The specific activity was 3700 U/mg and the corresponding copper content was 0.77 atoms Cu/subunit. The enzyme was quite unstable and overnight dialysis against EDTA or even prolonged dialysis against neutral phosphate buffer caused partial loss of activity and of copper and visible precipitation. It is likely that some losses occurred during the isolation procedure, and if these could have been prevented the copper content would have been 1.0 Cu/subunit and the specific activity would have been 4800 U/mg. It now appears likely that gram negative bacteria will commonly be found to contain a periplasmic Cu,Zn SOD.

Amino Acid Sequence↗
PubMed1996

Cartilage thickness measurement in magnetic resonance imaging.

To assess the accuracy of cartilage thickness measurements in magnetic resonance imaging (MRI), we compared data obtained by cartilage thickness measurements in MRI with corresponding histological sections of 14 human proximal tibial articular surfaces. Each proximal tibial articular surface was cut into five medial and lateral slices and each of these slices was divided into three sectors providing 420 sectors, 406 of which were evaluated in our study. The overall correlation coefficient (r) was 0.96. Topographical differences were found. The lowest correlation coefficient in our series was observed in the anterior part of the medial tibial plateau (r = 0.88). Cartilage thickness measurements in MRI were more accurate in cartilage thicker than 2 mm (r = 0.94) than in thinner cartilage layers (r = 0.73). There were no significant differences in cartilage thickness measurements in different grades of osteoarthritis. However, the mean percentage difference between cartilage thickness in MRI and histology was about 10% in our series.

Cartilage, Articular↗
PubMed1995

Lesions of the alar ligaments. In vivo and in vitro studies with magnetic resonance imaging.

STUDY DESIGN: This study analyzed anatomic characteristics of the alar ligaments and the possibility of imaging them with magnetic resonance imaging. Also determined was whether artificial ruptures of the alar ligament can be recognized experimentally. OBJECTIVE: To determine the ability of magnetic resonance imaging to visualize normal, torn, resected alar ligaments. SUMMARY OF BACKGROUND DATA: There are no studies about computed tomography or magnetic resonance imaging findings of alar ligaments and after anatomic sections. Direct visualization of the complete ligament is not possible for computed tomography. No precise diagnostic method for showing a ruptured alar ligaments has been described. Magnetic resonance imaging seems to be the method of choice for distinguishing between normal and pathologic soft tissue. METHODS: Fifteen specimens from accident victims underwent anatomic dissection. In addition, ligaments from three groups were examined: 1) eight volunteers, 2) seven patients, and 3) 17 fresh cadaveric specimen before anatomic exploratory dissection. In seven of these specimens, one ligament was cut to simulate an artificial disruption and magnetic resonance imaging was repeated. RESULTS: Lesions of the alar ligaments were found in four of 15 prepared specimens. Using magnetic resonance imaging, the alar ligaments could be identified in all volunteers, patients, and specimen except one. No ruptures were found in the 17 specimens. Of the seven resected specimens, all cuts could be demonstrated by magnetic resonance imaging. CONCLUSION: Magnetic resonance imaging is useful for showing lesions of the alar ligaments because of a high soft tissue contrast, plane independence imaging, possibility of functional scans, and secondary reconstruction from three-dimensional data sets.

Atlanto-Occipital Joint↗
PubMed1994

NADPH: ferredoxin oxidoreductase acts as a paraquat diaphorase and is a member of the soxRS regulon.

Soluble extracts of Escherichia coli contain four NADPH:paraquat diaphorases that were separable by anion-exchange HPLC over Mono Q. One of these was induced when the cells were exposed to paraquat. This was the case in a soxRS-competent strain but not in a soxRS-null strain, while a soxRS-constitutive strain overexpressed this diaphorase without the stimulus of exposure to paraquat. This NADPH:paraquat diaphorase could use cytochrome c or nitroblue tetrazolium as an electron acceptor, whereas O2 was a relatively poor acceptor. This diaphorase was identified as the NADPH:ferredoxin reductase. A role for reduced ferredoxin and flavodoxin in the adaptive soxRS response to oxidative stress and in the regulation of the redox status of soxR is discussed.

Amino Acid Sequence↗
PubMed1994

Membrane topology and mutational analysis of the TolQ protein of Escherichia coli required for the uptake of macromolecules and cell envelope integrity.

TolQ is a 230-amino-acid protein required to maintain the integrity of the bacterial envelope and to facilitate the import of both filamentous bacteriophage and group A colicins. Cellular fractionation experiments showed TolQ to be localized to the cytoplasmic membrane. Bacteria expressing a series of TolQ-beta-galactosidase and TolQ-alkaline phosphatase fusion proteins were analyzed for the appropriate enzyme activity, membrane location, and sensitivity to exogenously added protease. The results are consistent with TolQ being an integral cytoplasmic membrane protein with three membrane-spanning regions. The amino-terminal 19 residues as well as a small loop in the 155 to 170 residue region appear exposed in the periplasm, while the carboxy terminus and a large loop after the first transmembrane region are cytoplasmic. Amino-terminal sequence analysis of TolQ purified from the membrane revealed the presence of the initiating formyl methionine group, suggesting a rapid translocation of the amino-terminal region across the cytoplasmic membrane. Analysis of various tolQ mutant strains suggests that the third transmembrane region as well as parts of the large cytoplasmic loop are necessary for activity.

Amino Acid Sequence↗
PubMed1992

The structure of human mitochondrial manganese superoxide dismutase reveals a novel tetrameric interface of two 4-helix bundles.

The 2.2 A resolution crystal structure of recombinant human manganese superoxide dismutase, a homotetrameric enzyme that protects mitochondria against oxygen-mediated free radical damage, has been determined. Within each subunit, both the N-terminal helical hairpin and C-terminal alpha/beta domains contribute ligands to the catalytic manganese site. Two identical 4-helix bundles, symmetrically assembled from the N-terminal helical hairpins, form novel tetrameric interfaces that stabilize the active sites. Structurally altered polymorphic variants with reduced activity, such as tetrameric interface mutant Ile-58 to Thr, may produce not only an early selective advantage, through enhanced cytotoxicity of tumor necrosis factor for virus-infected cells, but also detrimental effects from increased mitochondrial oxidative damage, contributing to degenerative conditions, including diabetes, aging, and Parkinson's and Alzheimer's diseases.

Amino Acid Sequence↗
PubMed1992

Visualization of purified fibronectin-transglutaminase complexes.

It has been reported previously (Turner, P.M., and Lorand, L. (1989) Biochemistry 28, 628-635) that human erythrocyte transglutaminase forms a noncovalent complex with human plasma fibronectin near its collagen-binding domain. In the present study, we show by nondenaturing electrophoresis that guinea pig liver transglutaminase, similarly to the erythrocyte enzyme, forms a complex with human fibronectin. Studies of anisotropic shifts of fluorescein-labeled liver and erythrocyte transglutaminases, upon addition of fibronectin, indicated that both transglutaminases bind to fibronectin with a stoichiometry of about 2:1. Polymerization of fibrinogen by human erythrocyte transglutaminase was inhibited after complex formation with fibronectin. Complexes of fibronectin with either erythrocyte or liver transglutaminase were isolated by glycerol gradient zone sedimentation and examined by rotary shadowing electron microscopy. The globular transglutaminase could be readily identified binding to the thin fibronectin strand. The binding site for transglutaminase was within 5-10 nm of the N terminus of fibronectin, consistent with its proximity to the collagen-binding domain. Under some experimental conditions, the complex of fibronectin with erythrocyte transglutaminase appeared as a ring-shaped structure in which two transglutaminase molecules had probably dimerized. The molecular weight of the erythrocyte transglutaminase was determined by sedimentation equilibrium to be 71,440 +/- 830.

Animals↗
PubMed1991

TolA: a membrane protein involved in colicin uptake contains an extended helical region.

The group A colicins and the DNA of many single-stranded filamentous bacteriophage are able to use combinations of the Tol proteins to gain entrance into or across the membrane of Escherichia coli. The TolA protein is a 421-amino acid residue integral membrane protein composed of three domains. Domain I, consisting of the amino-terminal 47 amino acids, contains a 21-residue hydrophobic segment that anchors the protein in the inner membrane. The remaining 374 amino acids, containing the other two domains, reside in the periplasmic space. Domain III, consisting of the carboxyl-terminal 120 residues, is considered to be the functional domain based on the location of the tolA592 deletion mutation. The internal 262 amino acids comprise domain II, which connects domains I and III together via short regions of polyglycine. It contains a large number of 3- to 5-residue polyalanine stretches, many of which have a repeat of the sequence Lys-Ala-Ala-Ala-(Glu/Asp). Circular dichroism analysis of different portions of TolA show domain II to be predominantly alpha-helical in structure while domain III contains approximately 10% helical structure.

Amino Acid Sequence↗
PubMed1991

In vivo competition between iron and manganese for occupancy of the active site region of the manganese-superoxide dismutase of Escherichia coli.

Three forms of the dimeric manganese superoxide dismutase (MnSOD) were isolated from aerobically grown Escherichia coli which contained 2 Mn, 1 Mn and 1 Fe, or 2 Fe, respectively. These are designated Mn2-MnSOD, Mn,Fe-MnSOD, and Fe2-MnSOD. Substitution of iron in place of manganese, eliminated catalytic activity, decreased the isoelectric point, and increased the native electrophoretic anodic mobility, although circular dichroism, high performance liquid chromatography gel exclusion chromatography, and sedimentation equilibrium revealed no gross changes in conformation. Moreover, replacement of iron by manganese restored enzymatic activity. Fe2-MnSOD and the iron-superoxide (FeSOD) of E. coli exhibit distinct optical absorption spectra. These data indicate that the active site environments of E. coli MnSOD and FeSOD must differ. They also indicate that competition between iron and manganese for nascent MnSOD polypeptide chains occurs in vivo, and copurification of these variably substituted MnSODs can explain the substoichiometric manganese contents and the variable specific activities which have been reported for this enzyme.

Amino Acids↗
PubMed1990

Aseptic osteonecrosis of the humeral trochlea (Hegemann's disease).

A differential diagnosis of diseases affecting the elbow joint in children should also give due consideration to osteonecroses. They are very rare in the context of the humeral trochlea, the case with which we are concerned being one of a total of 15. In the light of this syndrome's relative rarity, we will report on the case of a 7-year-old boy. This is also the first time that a MR image of Hegemann's disease has been shown.

Adolescent↗
PubMed1990

[Functional diagnosis of early arthroses of the extremities].

Patient history and clinical examination are important for the diagnosis of degenerative joint disease. Here the typical statements of a patient suffering from early osteoarthritis are described and, as far as possible, explained. The joint in question must be systematically examined. Furthermore, the neighboring joints and soft-tissue structures, i.e., muscles, tendons etc., should be examined and evaluated with respect to their importance in hindering the functional chain. The neuroreflectory mechanisms involved herein are described.

Humans↗
PubMed1989

Differences between the manganese- and the iron-containing superoxide dismutases of Escherichia coli detected through sedimentation equilibrium, hydrodynamic, and spectroscopic studies.

The genome of Escherichia coli codes for two superoxide dismutases that may contain either iron (FeSOD) or manganese (MnSOD) at the active site. The crystal structures of MnSODs from two bacterial sources (but not E. coli) have been completed, and structural comparisons with the crystal structure of the FeSOD from either E. coli or Pseudomonas ovalis have been made. Despite the low degree (less than 50%) of sequence homology between the E. coli enzymes, the two proteins are suggested to be structurally homologous. Nonetheless, these enzymes exhibit absolute metal cofactor specificity in conferring enzymatic activity to the inactive apoenzyme. This observation is surprising considering the identity of the active site ligands and the similarities in their geometry and surrounding environment. Using analytical ultracentrifugation, we have determined that the solution properties of these two proteins are different. Thus dialysis of FeSOD but not of MnSOD against phosphate buffer in the presence or absence of EDTA caused dissociation of the homodimer. This dissociation appeared to be related to the loss of iron from native FeSOD. Thus, apoFeSOD but not apoMnSOD existed predominantly as a monomer at protein concentrations below 150 micrograms/mL. ApoMnSOD showed no evidence for dissociation under these conditions. Fluorescence data suggest that the tryptophan environments for the two enzymes are also different. The results of these physical measurements lead us to propose that subtle differences, perhaps at the subunit contact faces, exist in the structures of these crystallographically similar proteins.

Apoenzymes↗