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W Braun

Publications and source records attributed to W Braun.

At least 19 recordsLinked to original sources
PubMed1992

Comparison of the NMR solution structure and the x-ray crystal structure of rat metallothionein-2.

Metallothioneins are small cysteine-rich proteins capable of binding heavy metal ions such as Zn2+ and Cd2+. They are ubiquitous tissue components in higher organisms, which tentatively have been attributed both unspecific protective functions against toxic metal ions and highly specific roles in fundamental zinc-regulated cellular processes. In this paper a detailed comparison of the NMR solution structure [Schultze, P., Wörgötter, E., Braun, W., Wagner, G., Vasák, M., Kägi, J. H. R. & Wüthrich, K. (1988) J. Mol. Biol. 203, 251-268] and a recent x-ray crystal structure [Robbins, A. H., McRee, D. E., Williamson, M., Collett, S. A., Xoung, N. H., Furey, W. F., Wang, B. C. & Stout, C. D. (1991) J. Mol. Biol. 221, 1269-1293] of rat metallothionein-2 shows that the metallothionein structures in crystals and in solution have identical molecular architectures. The structures obtained with both techniques now present a reliable basis for discussions on structure-function correlations in this class of metalloproteins.

Amino Acid Sequence↗
PubMed1992

Cyclosporin A-cyclophilin complex formation. A model based on X-ray and NMR data.

The previously determined 3D NMR solution structure of cyclophilin-bound cyclosporin A (CsA) was docked onto the X-ray crystal structure of cyclophilin. Intermolecular nuclear Overhauser effects (NOE) between CsA and cyclophilin were used as constraints in a restrained energy minimization to generate a model of the complex which satisfied all the NOE distance constraints. The model shows that the residues 9 to 11 and 1 to 5 of the cyclic CsA molecule are in contact with cyclophilin. Comparing the model of the CsA-cyclophilin complex to the X-ray crystal structure of a complex of cyclophilin with a substrate for peptidyl-proline cis-trans isomerase activity, i.e. the linear tetrapeptide substrate ac-Ala-Ala-Pro-Ala-amc (ac, acetyl; amc, amidomethylcoumarin), one notices that the contacting peptide segments in the two ligands are oriented in opposite directions, and that the side chain of MeVal-11 of CsA superposes rather precisely with the position of the prolyl residue in ac-Ala-Ala-Pro-Ala-amc.

Amino Acid Isomerases↗
PubMed1992

Human cytomegalovirus (HCMV)-specific immunoglobulin E as a serologic marker for HCMV infection in immunocompromised patients.

An antibody capture assay using an enzyme-linked human cytomegalovirus (HCMV) antigen for the detection of specific immunoglobulin E (IgE) was established. IgG, M, and E responses to HCMV were studied in 497 sera obtained from 44 renal transplant recipients and 51 acquired immunodeficiency syndrome (AIDS) patients. The results were compared with those obtained from 58 HCMV-seropositive healthy individuals. HCMV-specific IgE was detected in 11 (91.7%) renal transplant recipients with primary HCMV infection. In contrast, antibodies of the IgG and IgM classes were detected in only 6 (50.0%) of these patients. Specific IgE was detected in 10 (90.9%) out of 11 renal allograft recipients suffering from secondary HCMV infection. Significant IgG titer rises and IgM were detected in 2 (18.2%) and 6 (54.6%) of these patients, respectively. IgG titer rises and IgM and IgE antibodies were seen in 5 (12.2%), 1 (2.4%) and 18 (43.9%) AIDS patients respectively. All healthy immunocompetent HCMV-seropositive individuals were tested IgE negative. The results obtained in our study indicate that IgE against HCMV is a more reliable serologic marker for primary and secondary HCMV infection than IgM in immunocompromised individuals, especially in organ transplant recipients, since it is not affected by the prophylactic application of HCMV hyperimmune globulin preparations.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Comparison of shell viral culture and serology for the diagnosis of human cytomegalovirus infection in neonates and immunocompromised subjects.

The present retrospective study compares the laboratory diagnosis of cytomegalic inclusion disease (CID) by the use of "shell vial culture" [i.e., immunoperoxidase staining of human cytomegalovirus (HCMV) early antigen in human fibroblasts 24 h postinoculation] to the results of serology (i.e. immunoglobulins IgG, IgM, and IgA HCMV antibody testing) in 21 infants with congenital or postnatally acquired HCMV infection, 5 patients with lymphoproliferative disorders, 35 human immunodeficiency virus (HIV)-seropositive patients who met the Centers for Disease Control (CDC) criteria for stages IVA and IVB of HIV infection, and 115 patients suffering from the acquired immunodeficiency syndrome, AIDS (stages IVC-IVE according to CDC criteria). HCMV infection was diagnosed by means of the shell vial culture inoculated with patient samples (e.g., urine, bronchoalveolar lavage, induced sputum, etc.) and serology in 163 (92.6%) and 65 (36.9%) patients, respectively. Viral shedding was detected by shell vial culture in 100% of the neonates, 80% of the patients suffering from lymphoproliferative disorders, 100% of the AIDS related complex (ARC) and 89.6% of the AIDS patients. In contrast, serologic testing for HCMV-specific antibodies was positive in only 28.6%, 42.9%, and 34.8% of the neonates, ARC, and AIDS patients, respectively. In lymphoma patients, serologic testing gave identical results (80%) to the shell vial culture technique. With the use of the shell vial procedure, active HCMV infection in immunocompromised subjects and neonates can be recognized more reliably than by serologic testing. Nevertheless, in a low percentage of patients (7.4%), virus isolation by the shell vial culture may fail to detect HCMV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[Distal intra-articular humerus fractures in adults. Results of surgical treatment].

Intra-articular fractures of the distal end of the humerus are severe injuries because stable anatomic reduction is difficult to achieve even operatively. They are often accompanied by nerve lesions and often lead to heterotopic para-articular ossifications. Functional recovery is only rarely complete. Follow-up of 54 cases of operatively treated fractures of this kind showed 56% excellent and good late results. In immediate operations we observed fewer infections, less ossification, and better functional results than after delayed operative treatment. We therefore recommend careful examination for nervous deficits, immediate stable internal fixation of the fractures displaying the ulnar nerve, and handling the soft tissue as gently as possible to avoid additional damage. Postoperative physiotherapy should also be started immediately.

Elbow Joint↗
PubMed1992

[Osseous leiomyoma--a first-time description].

In a 54-year old housewife presenting with left hip pain due to a circumscribed intraosseous lesion of the femoral neck, histological assessment following resection showed a benign intraosseous leiomyoma. Years ago a diagnosis of disseminated peritoneal leiomyomatosis had been made.

Bone Transplantation↗
PubMed1991

The NMR structure of cyclosporin A bound to cyclophilin in aqueous solution.

Cyclosporin A bound to the presumed receptor protein cyclophilin was studied in aqueous solution at pH 6.0 by nuclear magnetic resonance spectroscopy using uniform 15N- or 13C-labeling of cyclosporin A and heteronuclear spectral editing techniques. Sequence-specific assignments were obtained for all but one of the cyclosporin A proton resonances. With an input of 108 intramolecular NOEs and four vicinal 3JHN alpha coupling constants, the three-dimensional structure of cyclosporin A bound to cyclophilin was calculated with the distance geometry program DISMAN, and the structures resulting from 181 converged calculations were energy refined with the program FANTOM. A group of 120 conformers was selected on the basis of the residual constraint violations and energy criteria to represent the solution structure. The average of the pairwise root-mean-square distances calculated for the backbone atoms of the 120 structures was 0.58 A. The structure represents a novel conformation of cyclosporin A, for which the backbone conformation is significantly different from the previously reported structures in single crystals and in chloroform solution. The structure has all peptide bonds in the trans form, contains no elements of regular secondary structure and no intramolecular hydrogen bonds, and exposes nearly all polar groups to its environment. The root-mean-square distance between the backbone atoms of the crystal structure of cyclosporin A and the mean of the 120 conformers representing the NMR structure of cyclosporin A bound to cyclophilin is 2.5 A.

Amino Acid Isomerases↗
PubMed1991

Two-dimensional 1H nuclear magnetic resonance study of AaH IT, an anti-insect toxin from the scorpion Androctonus australis Hector. Sequential resonance assignments and folding of the polypeptide chain.

Sequence-specific nuclear magnetic resonance assignments for the polypeptide backbone and for most of the amino acid side-chain protons, as well as the general folding of AaH IT, are described. AaH IT is a neurotoxin purified from the venom of the scorpion Androctonus australis Hector and is specifically active on the insect nervous system. The secondary structure and the hydrogen-bonding patterns in the regular secondary structure elements are deduced from nuclear Overhauser effects and the sequence locations of the slowly exchanging amide protons. The backbone folding is determined by distance geometry calculations with the DISMAN program. The regular secondary structure includes two and a half turns of alpha-helix running from residues 21 to 30 and a three-stranded antiparallel beta-sheet including peptides 3-5, 34-38, and 41-46. Two tight turns are present, one connecting the end of the alpha-helix to an external strand of the beta-sheet, i.e., turn 31-34, and another connecting this same strand to the central one, i.e., turn 38-41. These structure elements are very similar to the secondary structure reported in single crystals for either variant 3 from the scorpion Centruroides sculpturatus Ewing (CsE V3) or toxin II from the scorpion A. australis Hector (AaH II). The differences in the specificity of these related proteins, which are able to discriminate between mammalian and insect voltage-dependent sodium channels of excitable tissues, are most probably brought about by the position of the C-terminal peptide with regard to a hydrophobic surface common to all scorpion toxins examined thus far. This surface is made of an aromatic cluster that is surrounded by long hydrophobic side-chain residues, as well as the loops protruding out of it. Thus, the interaction of a given scorpion toxin with its receptor might well be governed by the presence of this solvent-exposed hydrophobic surface, whereas adjacent areas modulate the specificity of the interaction.

Amino Acid Sequence↗
PubMed1991

Efficient computation of three-dimensional protein structures in solution from nuclear magnetic resonance data using the program DIANA and the supporting programs CALIBA, HABAS and GLOMSA.

A novel procedure for efficient computation of three-dimensional protein structures from nuclear magnetic resonance (n.m.r.) data in solution is described, which is based on using the program DIANA in combination with the supporting programs CALIBA, HABAS and GLOMSA. The first part of this paper describes the new programs DIANA. CALIBA and GLOMSA. DIANA is a new, fully vectorized implementation of the variable target function algorithm for the computation of protein structures from n.m.r. data. Its main advantages, when compared to previously available programs using the variable target function algorithm, are a significant reduction of the computation time, and a novel treatment of experimental distance constraints involving diastereotopic groups of hydrogen atoms that were not individually assigned. CALIBA converts the measured nuclear Overhauser effects into upper distance limits and thus prepares the input for the previously described program HABAS and for DIANA. GLOMSA is used for obtaining individual assignments for pairs of diastereotopic substituents by comparison of the experimental constraints with preliminary results of the structure calculations. With its general outlay, the presently used combination of the four programs is particularly user-friendly. In the second part of the paper, initial results are presented on the influence of the novel DIANA treatment of diastereotopic protons on the quality of the structures obtained, and a systematic study of the central processing unit times needed for the same protein structure calculation on a range of different, commonly available computers is described.

Algorithms↗
PubMed1991

Complete relaxation matrix refinement of NMR structures of proteins using analytically calculated dihedral angle derivatives of NOE intensities.

A new method for refining three-dimensional (3D) NMR structures of proteins is described, which takes account of the complete relaxation pathways. Derivatives of the NOE intensities with respect to the dihedral angles are analytically calculated, and efficiently evaluated with the use of a filter technique for identifying the dominant terms of these derivatives. This new method was implemented in the distance geometry program DIANA. As an initial test, we refined 30 rigid distorted helical structures, using a simulated data set of NOE distance constraints for a rigid standard alpha-helix. The final root-mean-square deviations of the refined structures relative to the standard helix were less than 0.1 A, and the R-factors dropped from values between 7% and 32% to values of less than 0.5% in all cases, which compares favorably with the results from distance geometry calculations. In particular, because spin diffusion was not explicitly considered in the evaluation of 'exact' 1H-1H distances corresponding to the simulated NOE intensities, a group of nearly identical distance geometry structures was obtained which had about 0.5 A root-mean-square deviation from the standard alpha-helix. Further test calculations using an experimental NOE data set recorded for the protein trypsin inhibitor K showed that the complete relaxation matrix refinement procedure in the DIANA program is functional also with systems of practical interest.

Magnetic Resonance Spectroscopy↗
PubMed1991

[Plate osteosynthesis in the treatment of open femoral shaft fractures. Course in 65 cases].

In this study the results of 65 open femoral shaft fractures treated by plating are reported. The follow up of these cases proved that the osteosynthesis by plate is the treatment of choice in most of open femoral shaft fractures. The overall rate of postoperative complications was 23%. There were 5 deep infections concerning third-grade open fractures in two patients. In 10 cases a second operation was necessary because of delayed union; in 8 of these 10 fractures a homologous cancellous bone graft was performed during the first operation. Regarding to these complications an autologous bone transplantation should be carried out after primary plating of open femoral shaft fractures in order to improve vascularity and stability of the fracture. To reduce the unsatisfying rate of infections in III.-grade open fractures the treatment by external pin fixation in these cases should be preferred.

Adolescent↗
PubMed1991

[Conservative therapy of fractures of the thoracic and lumbar spine. Indications, treatment regimen, results].

In this study the results of conservatively treated stable fractures of the thoracolumbar spine in 112 cases are reported. The follow-up of these patients was carried out by clinical and radiological examinations. It proved that functional treatment used in 94% of all cases was superior in its results and lack of pain to Böhler the method according of closed correction and immobilization by cast. The radiological examination showed no coherence between narrowing of the verebra after early mobilization and function of the spine. A three point corset in addition to this therapy seems to be without any advantage.

Adult↗
PubMed1991

[Femoral head preserving therapy in medial femoral neck fractures. A clinical study of the effects of treatment method on the outcome].

The main problem with fractures of the femoral neck is the high incidence of avascular necrosis and non-union. While the rate of pseudarthroses has been lowered by treatment with stable compression screws, no effect of this technique on the incidence of head necrosis is evident. The reasons for this are rupture of vessels, wide dislocation of fragments and diminution of blood supply owing to intracapsular hematoma. Since 1982 we have been using a defined indications and therapy schedule for these fractures, which is based on the main principle of open operative treatment in younger patients. This procedure is the only one that makes accurate reduction and stable internal fixation of fragments possible. With the opening of the capsule and evacuation of the hematoma pressure on the blood vessels is relieved. The analysis of data recorded in 81 patients treated with open reduction and stable internal fixation revealed that poor functional results and avascular necrosis occur especially in fractures of Garden's stages III and IV that are operated on longer than 6 h after the trauma is sustained. Therefore, the operation should be performed as soon as possible as an emergency procedure to reduce the likelihood of such severe complications.

Femoral Neck Fractures↗
PubMed1990

Diagnosis, therapy, and outcome of ventricular septal defects in the 1st year of life: a two-dimensional colour-Doppler echocardiography study.

Between January 1987 and July 1989 a ventricular septal defect (VSD) as a single cardiac lesion was detected in 269 small infants aged less than 1 year. The diagnosis was achieved by two-dimensional echocardiography and Doppler colour flow mapping using subcostal, parasternal, apical, and suprasternal views. VSDs were divided into perimembraneous, muscular, malalignment, and subpulmonary defects. Septal defects in complex lesions and atrioventricular defects were excluded. In group 1 (174 infants up to 4 weeks of age, mean 10 days) 125 muscular (71.8%), 35 (20.1%) perimembraneous, 12 (6.9%) malalignment, and 2 (1.1%) subpulmonary defects were diagnosed. One baby had a combined perimembraneous and muscular defect. In another baby a malalignment defect was associated with an av-canal. In group 2 (95 infants aged 4 weeks to 1 year, mean 4.0 months), 57 (60%) muscular, 32 (33.6%) perimembraneous and 6 (6.3%) malalignment defects were found. Within the maximum observation period of 13 months, spontaneous closure occurred in 72 (42.6%) of 169 infants who had a sufficient follow up. Sixty-four had a muscular (88.9%) and 8 (11.1%) a perimembraneous defect. Surgical intervention was required in 11 patients: five perimembraneous defects were closed, one was palliated. Five infants with a malalignment defect were palliated. The malalignment defect frequently needed surgical intervention even in newborns; it never closed spontaneously. About 10% of patients with perimembraneous septal defect required surgery. Spontaneous closure rarely occurred in early infancy. Muscular VSDs were most frequent but virtually never required therapy. Spontaneous closure rate was about 50% during the 1st year of life.

Echocardiography, Doppler↗