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Biomedical subjects

O Meyer

Publications and source records attributed to O Meyer.

At least 361 records · Page 20Linked to original sources
PubMedDate not supplied

[Epiduroscopic diagnosis and treatment of epidural adhesions in chronic back pain syndrome of patients with previous surgical treatment: first results of 31 interventions].

AIM: Scars in the epidural space play an important role in the chronic lumbar pain syndrome of patients with previous surgical treatment. The results of surgical resection are frequently unsatisfactory. Discrepancies to imaging diagnostics are conspicuous. These are known from experience with endoscopic operations. Minimal adhesions may promote pain. Epiduroscopy is available for visualization of the epidural space. The objective of this study was to examine its possibilities in patients with previous surgical treatment. METHOD: 31 patients with chronic lumbar pain syndrome who had previously received surgical treatment were operated epiduroscopically. Mechanical instruments and the holmium:YAG laser were used for epidural adhesion. RESULTS: All patients showed adhesions. 24 patients also presented with adhesions on the contralateral side. There were marked discrepancies between imaging and intraoperative findings. The use of mechanical instruments was limited. The use of laser fibers resulted in greater possibilities. Back pain could be better influenced than leg pain. The procedure was limited by still-existing technical problems. CONCLUSION: Epiduroscopy offers a novel view of this compartment. Minimal adhesions which are not visible in imaging ean promote pain. They can be partially diagnosed and treated by epiduroscopy. There are still marked limitations to epiduroscopy due to technical problems. These must be minimized.

Adult↗
PubMedDate not supplied

Selenium in biology: facts and medical perspectives.

Several decades after the discovery of selenium as an essential trace element in vertebrates approximately 20 eukaryotic and more than 15 prokaryotic selenoproteins containing the 21st proteinogenic amino acid, selenocysteine, have been identified, partially characterized or cloned from several species. Many of these proteins are involved in redox reactions with selenocysteine acting as an essential component of the catalytic cycle. Enzyme activities have been assigned to the glutathione peroxidase family, to the thioredoxin reductases, which were recently identified as selenoproteins, to the iodothyronine deiodinases, which metabolize thyroid hormones, and to the selenophosphate synthetase 2, which is involved in selenoprotein biosynthesis. Prokaryotic selenoproteins catalyze redox reactions and formation of selenoethers in (stress-induced) metabolism and energy production of E. coli, of the clostridial cluster XI and of other prokaryotes. Apart from the specific and complex biosynthesis of selenocysteine, selenium also reversibly binds to proteins, is incorporated into selenomethionine in bacteria, yeast and higher plants, or posttranslationally modifies a catalytically essential cysteine residue of CO dehydrogenase. Expression of individual eukaryotic selenoproteins exhibits high tissue specificity, depends on selenium availability, in some cases is regulated by hormones, and if impaired contributes to several pathological conditions. Disturbance of selenoprotein expression or function is associated with deficiency syndromes (Keshan and Kashin-Beck disease), might contribute to tumorigenesis and atherosclerosis, is altered in several bacterial and viral infections, and leads to infertility in male rodents.

Animals↗
PubMedDate not supplied

The role of Se, Mo and Fe in the structure and function of carbon monoxide dehydrogenase.

CO dehydrogenase (EC 1.2.99.2) catalyzes the oxidation of CO according to the following equation: CO + H2O-->CO2 + 2 e- + 2 H+. It is a selenium-containing molybdo-iron-sulfur-flavoenzyme, which has been crystallized and structurally characterized in its oxidized state from the aerobic CO utilizing bacteria Oligotropha carboxidovorans and Hydrogenophaga pseudoflava. Both CO dehydrogenase structures show only minor differences, and the enzymes are dimers of two heterotrimers. Each heterotrimer is composed of a molybdoprotein, a flavoprotein, and an iron-sulfur protein. CO oxidation takes place at the molybdoprotein which contains a 1:1 mononuclear complex of molybdopterin-cytosine dinucleotide and a Mo-ion, along with a catalytically essential S-selanylcysteine. The latter is appropriately positioned in the SeMo-active site by a unique VAYRCSFR active site loop. In H. pseudoflava the arginine preceeding the cysteine in the active site loop is modified to a Cgamma-hydroxy arginine residue which has no obvious function. The substituents in the first coordination sphere of the Mo-ion are the enedithiolate sulfur atoms of the molybdopterin-cytosine dinucleotide, two oxo- and a sulfido-group. Extended X-ray absorption fine structure spectroscopy (EXAFS), along with the crystal structure of CO dehydrogenase (23.2 U mg(-1)) at 1.85 A resolution, have identified a sulfur atom at 2.3 A from the Mo-ion. The sulfur reacts with cyanide yielding thiocyanate. The corresponding inactive desulfo-CO dehydrogenase shows a typical desulfo inhibited-type of Mo-electron paramagnetic resonance (EPR) spectrum. Structural changes at the SeMo-site during catalysis are suggested by the Mo to Se distance of 3.7 A and the Mo-S-Se angle of 113 degrees in the oxidized enzyme which increase to 4.1 A, and 121 degrees, respectively, in the reduced enzyme. The intramolecular electron transport chain in CO dehydrogenase involves the following prosthetic groups and minimal distances: CO-->[Mo of the molybdenum cofactor] - 14.6 A - [2Fe-2S]I - 12.4 A - [2Fe-2S]II - 8.7 A - [FAD].

Aldehyde Oxidoreductases↗
PubMedDate not supplied

Multicenter validation of recombinant, natural and synthetic antigens used in a single multiparameter assay for the detection of specific anti-nuclear autoantibodies in connective tissue disorders.

OBJECTIVES: We investigated the feasibility of using a single multi-parameter test based mainly on recombinant autoantigens for the detection of anti-nuclear autoantibodies, and analyzed the agreement between this test format and conventional techniques. METHODS: The presence of autoantibodies was determined by a line immunoassay (LIA) in 755 sera derived from patients with different autoimmune connective tissue disorders. All sera were previously tested by standard assays that are routinely used at the 8 participating European centers. RESULTS: The overall sensitivity and specificity of autoantibody detection by LIA was similar or higher as compared to combined conventional techniques (CCT). In particular, the detection of anti-Ro52 in systemic lupus erythematosus (SLE) sera (P = 0.004) and anti-LA in both SLE (P < 0.0009) and in Sjögren's syndrome (P < 0.0009) sera was significantly more sensitive when using LIA compared to CCT. By contrast, CCT was never more sensitive than LIA for any of the markers. CONCLUSION: The LIA is a reliable alternative to a combination of conventional techniques for the detection of specific anti-nuclear autoantibodies. The multi-parameter test also reveals autoantibody reactivities that may not be detected when only a limited number of conventional techniques are applied.

Antibodies, Antinuclear↗
PubMedDate not supplied

Differences in understanding and application of 1987 ACR criteria for rheumatoid arthritis and 1991 ESSG criteria for spondylarthropathy. A pilot survey.

OBJECTIVES: To determine areas of agreement and disagreement among experts in the interpretation of the published criteria for RA (ACR) and spondylarthropathies ( ESSG). METHODS: Thirty-two experts (16 from France and 16 from 10 other countries) replied anonymously to a mailed questionnaire. RESULTS: Tenosynovitis and 'sausage-like' painless swelling of the toes were considered as criteria for RA by 18 and 14 experts, respectively. The definition of symmetry differed widely among experts (symmetry of only one group of joints was sufficient for 13). Twenty-five experts considered erosions of other joints than the wrists and fingers as a criterion for RA, 17 thought that fulfilment of criteria could be achieved cumulatively, and 19 would appreciate clarifications of the current criteria. Among possible clarifications for RA, it was frequently recommended that morning stiffness and nodules be eliminated and that new marker antibodies, X-rays of the feet, and exclusion criteria be added. Twenty-three of the 29 experts who gave an opinion (79%) agreed with the notion of SP in the absence of axial signs and sacroiliitis, 26/31 (84%) indicated that a patient can have both RA and SP, and 19/30 (63%) thought that RA and SP could be regarded as syndromes more than diseases. Only 5/32 experts relied more on the criteria than on their clinical judgement in diagnosing RA. CONCLUSIONS: There would seem to be a needfor the optimisation of RA and ESSG criteria, particularly within the context of early arthritis.

Arthritis, Rheumatoid↗
PubMedDate not supplied

Vascular endothelial cell injury in progressive systemic sclerosis and other connective tissue diseases.

The growth inhibition of in vitro vascular endothelial cell cultures by sera from patients with connective tissue diseases was studied. Seven out of 30 sera from patients with progressive systemic sclerosis (PSS) exhibited a cytotoxic effect. The cytotoxic serum factor(s) was not specific to patients with PSS, it was also demonstrated in sera from patients with other connective tissue diseases with vascular symptoms (11 out of 27 sera from patients with a mixed connective tissue disease, MCTD; 5 out of 34 sera from patients with a systemic lupus erythematosus, SLE). The cytotoxic effect was not specific for vascular endothelial cells, it was also found on fibroblast cells cultures. Inhibitor(s) of cell growth in vitro was independent of antinuclear and anticytoplasmic antibodies and appeared as a common feature of all connective tissue diseases with vascular symptoms.

Antibodies↗
PubMedDate not supplied

Relapsing polychondritis - pathogenic role of anti-native collagen type II antibodies. A case report with immunological and pathological studies.

A patient with relapsing polychondritis and Sjogren's syndrome is reported. Diagnosis was confirmed by ear cartilage biopsy. Antibodies against rat costal cartilage were present in the patient's serum. Antinative collagen type II antibodies were detected using a passive hemagglutination technique and the titer grossly correlated with the clinical course. Direct immunofluorescence using the patient's ear cartilage as a target suggested that anti-collagen antibodies might play a major pathogenic role in the course of relapsing polychondritis.

Antibodies↗
PubMedDate not supplied

Anti-RA 33 antinuclear autoantibody in rheumatoid arthritis and mixed connective tissue disease: comparison with antikeratin and antiperinuclear antibodies.

Besides rheumatoid factor (RF), antikeratin antibodies (AKA) and antiperinuclear factor (APN), anti-RA 33 antibody has been described as a highly specific antinuclear antibody for rheumatoid arthritis (RA). In this study RA 33 antibodies were detected using Western blotting with HeLa cell nuclear extract in a group of 94 RA patients and 259 controls. Anti-RA 33 was present in 35% of 94 RA patients, with a similar frequency in RF positive (32%) and RF-negative (45%) RA patients. RA-33 antibody was also present in 60% of a group of 30 patients with anti-U1 RNP positive mixed connective tissue disease. The specificity of anti-RA 33 for RA was 84.6%. Anti-RA 33 antibody was already present in sera from 23.5% of 18 patients with RA of less than one year's duration. Anti-RA 33 antibody was the only positive immunological marker in 3/20 cases of seronegative adult RA. No correlations were found between anti-RA 33 antibody and AKA or APF. Patients with erosive RA and patients whose ESR was > or = 50 mm after 1 hour were more likely to be anti-RA 33 positive (47.6% vs 24.4% and 42.8% vs 29.4%). These results suggest that anti-RA 33 antibody, in the absence of anti-U1-RNP antibodies, can be added to the list of the helpful serological markers for rheumatoid arthritis.

Adult↗
PubMedDate not supplied

[Superantigens and their implication in autoimmune diseases].

Superantigens, unlike conventional antigens, are capable of stimulating cell growth and differentiation of a large proportion of T cells (10 -40%). There are two types of superantigens: endogenous retroviral superantigens (described only in mice) and bacterial superantigens. Bacterial superantigens are heat-resistant enterotoxins responsible for Staphylococcus food poisoning or toxic shock syndromes. T lymphocyte proliferation is associated with production of large quantities of cytokines, including interleukin-1, 2, 4, 6 and tumour necrosis factor which induce the symptoms observed in toxic syndromes. These superantigens form trimolecular complexes with the beta chains on the outer peptide pouch of class II HLA molecules and with certain families of V beta chains of the T-cell receptors on CD4 and CD8 lymphocytes. Unlike conventional antigens, superantigens do not have to be processed in small-sized peptides before presentation to T-cell receptors by the class II HLA molecules. The late consequences of T-cell activation by superantigens are either a deletion of the T-lymphocytes carrying V beta chains in families specific for a superantigen, or an anergy. The oligoclonal characteristic of T-lymphoid populations infiltrating the central nervous system, the synovial membrane or the salivary glands suggests that superantigens are implicated in the pathogenesis of certain autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, and Sjögren's syndrome. Certain Staphylococcus superantigens could be the cause of Kawasaki's syndrome.

Animals↗
PubMedDate not supplied

Neurological manifestations of systemic lupus erythematosus: role of antiphospholipid antibodies.

Antiphospholipid antibodies (APL) are associated with venous and arterial thrombosis in SLE patients. Various thrombotic and non-thrombotic neurological manifestations have been reported in SLE but whether or not they are related to the presence of APL antibodies remains uncertain. To assess the possible association between neurological involvement in SLE and APL antibodies, IgG anticardiolipin antibodies (IgG ACL) were looked for using an ELISA technique in 92 consecutive SLE patients seen over a one-year period. Other APL determinations included VDRL and lupus anticoagulant (LAC) testing using APTT and the diluted thromboplastin time. Twenty-four SLE patients presented with neurological manifestations (40 episodes): 15/24 (62.5%) were found positive for APL antibodies (11 VDRL, 8 LAC, 7 ACL antibodies) versus 22/68 patients (32%) without neurological symptoms (p < 0.01). APL antibodies antedated neurological symptoms in 13/16 cases. Neurological manifestations were subsequently divided into 3 groups: thrombotic (n = 14), psychosis and convulsions (n = 15), miscellaneous (n = 10). No correlation was found between APL antibodies and any of the 3 subgroups. Among patients with neurological SLE, APL antibodies were present in two with valvular heart disease, as well as in seven with a history of either deep vein thrombosis, livedo reticularis or miscarriage. Among 7 patients with thrombocytopenia and neurological symptoms, 6 had APL antibodies. These data suggest that APL syndrome is associated with neuro-ophthalmological manifestations of SLE regardless of whether or not the mechanism of neurological involvement is thrombotic. SLE patients with APL antibodies may be at risk for future neurological manifestations. However, it is still questionable that APL positivity has definite therapeutic consequences.

Adolescent↗
PubMedDate not supplied

Effect of potato starch, cornstarch and sucrose on aberrant crypt foci in rats exposed to azoxymethane.

Studies have shown that different kinds of carbohydrates are able to modify the development of colo-rectal cancer in animals as well as humans. In the present study with rats sucrose and two types of starches were investigated for their effects on the development of aberrant crypt foci (ACF), which have been proposed to represent preneoplastic lesions of colorectal cancer. Fifty-six three-week-old male Wistar rats were randomly assigned to four groups and dosed subcutaneously with AOM (15 mg/kg body wt) once a week for 2 weeks. At the end of the dosing period the animals were allocated to their respective diets. Group I was fed the basic diet; in Group II the carbohydrate pool in the diet was replaced by sucrose, in Group III by potato starch and in Group IV by cornstarch. Animals receiving the potato starch diet showed a statistically significant reduction in body weight gain. A statistically significantly lower number of ACF in all categories but small were demonstrated in animals given potato starch, and in addition an effect was seen in the relative distribution of ACF with fewer of the larger ACF. No effect of sucrose or cornstarch was seen. Explanations of the inhibitory effect in the potato starch group on the development of ACF could either be the lower daily caloric intake or the substantial amounts of resistant starch in the potato starch used.

Animals↗