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Biomedical subjects

S Muller

Publications and source records attributed to S Muller.

352 records · Page 20Linked to original sources
PubMedDate not supplied

Meningiomas of the paranasal sinuses.

Extracranial meningiomas are rare tumors, comprising approximately 2% of all meningiomas. Previously reported sites include the orbit, parapharyngeal space, and rarely, the paranasal sinuses. A retrospective chart review of patients with meningiomas was performed over the last 25 years, and three patients were identified with meningiomas involving the paranasal sinuses. The locations included the frontal sinus, the ethmoid sinus, and the sphenoid sinus. Presenting symptoms included facial pain and nasal obstruction; two patients noted facial swelling. Diagnosis was established via endoscopic transnasal biopsy in two patients. Computed tomographic (CT) guided biopsy was utilized to confirm the diagnosis in the third patient. Surgical extirpation was successfully performed with tumors arising from the ethmoid and frontal sinuses. The patient with neoplasm in the sphenoid sinus underwent radiation therapy. Extracranial meningiomas of the paranasal sinuses are rare tumors that may present a diagnostic and therapeutic challenge. We present three cases and discuss the clinical presentation, radiographic findings, diagnostic evaluation, and treatment options.

Adolescent↗
PubMedDate not supplied

Influence of mechanical stress on cell viability.

The cartilage is a hydrated connective tissue in joints that withstands and distributes mechanical forces. The chondrocytes utilize mechanical signals to regulate their metabolic activity through complex biological and biophysical interactions with the extracellular matrix (ECM). The aim of this work was to study the influence of mechanical stress on cells behavior cultured in 3D biosystems (alginate and alginate supplemented with hyaluronate). After mechanical stimulation, cell viability and cell death process were the main studied parameters. Our results indicated that viability and cell cycle progression were inhibited under mechanical stimulation, as far as the extracellular matrix was not yet synthesized. In contrast, on day 21, the mechanical stimulation had positive effect on these parameters.

Alginates↗
PubMedDate not supplied

IL-1beta synthesis by chondrocyte analyzed by 3D microscopy and flow cytometry: effect of Rhein.

Several factors are known to be involved in the destruction of the articular cartilage. Interleukin-1 (IL-1) plays an important role in the pathogenesis of osteoarthritis (OA) either directly or through the stimulation of catabolic factors. The action of IL-1 on articular cartilage is multifaceted and it most likely plays an important role in the mechanism of cartilage destruction. IL-1 suppresses the synthesis of the cartilage matrix components and promotes the degradation of cartilage matrix macromolecules. Diacerein is an anthraquinone molecule that has been shown to reduce the severity of OA, both in man and in animal models. The present study was designed to evaluate in vitro effects of diacerein on IL-1beta expression in LPS or IL-1alpha stimulated chondrocytes. Intracellular IL-1beta production was analysed in articular chondrocytes cultured in monolayer or in alginate 3D-biosystems in the presence of lipopolysaccharide (LPS) or IL-1alpha, with or without diacerein. The results show that LPS and IL-1alpha increase intracellular IL-1beta and Diacerein inhibited LPS-induced and IL-1alpha induced IL-1beta production by articular chondrocytes. Moreover, the effect of mechanical stimulation was analysed. An inhibitory effect of DAR at therapeutic concentrations on IL-1beta production in articular chondrocytes is suggested.

Alginates↗
PubMedDate not supplied

Longitudinal analysis of antibodies to histones, Sm-D peptides and ubiquitin in the serum of patients with systemic lupus erythematosus, rheumatoid arthritis and tuberculosis.

A longitudinal analysis of 12 lupus patients has been undertaken to assess their autoantibody reactivity by ELISA with histones, Sm-D peptides, ubiquitin and DNA. As controls patients with rheumatoid arthritis and tuberculosis were studied. Whereas the control groups showed little evidence of autoantibody reactivity 25% or more of the lupus patients had raised levels of autoantibodies against eight of the nine antigens tested. Of particular note was the fact that approximately 70% of the blood tested possessed antibodies reacting with Sm-D peptide 1-20. In contrast only one patient had anti-Sm antibodies by counter immunoelectrophoresis. In general the levels of antibodies to core histones reflected disease activity unlike the levels of anti-H1 antibodies. High levels of antibodies to ubiquitin often seemed to correlate inversely with active lupus and DNA antibody levels.

Adult↗
PubMedDate not supplied

Total chemical synthesis of ubiquitin using BOP reagent: biochemical and immunochemical properties of the purified synthetic product.

The complete ubiquitin molecule (76 residues) has been synthesized by the solid-phase method of Merrifield by using BOP as the coupling reagent. The crude product was purified by gel filtration, middle-pressure liquid chromatography and ion-exchange chromatography. Seven mg of a ca. 95% pure peptide was finally obtained; the overall yield of the synthesis was 1%. The final product was controlled by amino acid analysis and sequencing, HPLC and FAB-Mass spectrometry. Synthetic ubiquitin was found to be antigenically active in immunoblotting experiments and in an enzyme-linked immunosorbent assay with anti-ubiquitin antibodies as well as with anti-ubiquitin autoantibodies from autoimmune patients. Its activity was controlled in a conjugation enzymatic system and was found similar to that of commercial ubiquitin. The successful total synthesis of ubiquitin opens the way to the preparation of various stable analogs that should be useful for studying the intracellular metabolism of this molecular and its involvement in the protein degradation pathway.

Amino Acid Sequence↗
PubMedDate not supplied

Synthesis and antigenic properties of reduced peptide bond pseudopeptide analogues of a histone H3 hexapeptide.

Pseudopeptide analogues of the C-terminal hexapeptide of histone H3 (-Ile-Arg-Gly-Glu-Arg-Ala-OH) were obtained by systematically replacing, in each analogue, one peptide bond at a time by a reduced peptide bond psi (CH2-NH). The resulting analogues were then examined, in ELISA and in the BIAcore system, for their ability to bind polyclonal and monoclonal antibodies generated against the parent natural peptide and the protein. The comparative results show that reduced bond pseudopeptide analogues can mimic the parent peptide. These results present the first unequivocal example for the potent applicability of reduced peptide bond pseudopeptides in the immunological field.

Amino Acid Sequence↗
PubMedDate not supplied

Enhanced immunogenicity and cross-reactivity of retro-inverso peptidomimetics of the major antigenic site of foot-and-mouth disease virus.

Retro-inverso analogues of peptides corresponding to the major antigenic site 141-159 of VP1 from two foot-and-mouth disease virus variants have been synthesized and tested for their antigenic and immunogenic properties. Antibodies to the L- and retro-inverso peptides were produced by injecting rabbits with peptides covalently coupled to small unilamellar liposomes containing monophosphoryl lipid A as adjuvant. When compared to the antibody response raised against the L-peptides, the duration of the IgG response that was induced by the retro-inverso peptides was significantly longer and the titer of anti-peptide antisera was much higher. Antibodies to retro-inverso peptides cross-reacted equally well with the respective parent L-peptides. These results, obtained with a viral sequence which was found previously to represent a good candidate for possible vaccination, show that retro-inverso peptidomimetics could be useful for enhancing the immunogenicity of peptides.

Amino Acid Sequence↗
PubMedDate not supplied

Highly specific, cross-reactive sequences recognized by an anti-HBsAg antibody identified from a positional scanning synthetic combinatorial library.

The binding specificity of a monoclonal antibody (MAb 12) known to recognize the surface antigen of hepatitis B virus (HBsAg) was studied using a positional scanning synthetic combinatorial library. A hexapeptide library totaling more than 30 x 10(6) sequences, made up of 120 mixtures having a single position defined with individual amino acids and the remaining five positions composed of mixtures of amino acids, was screened by competitive enzyme-linked immunosorbent assay (ELISA). This led to the identification of Ac-STTSMM-NH2 (IC50 = 170 nM), which specifically inhibited the interaction between HBsAg and MAb 12. One of the most active individual mixtures from the library was Ac-XXXPXX-NH2; however, none of the individual peptides synthesized containing proline at the fourth position showed significant activity (IC50 > 100,000 nM). To identify the individual peptide(s) responsible for the activity of Ac-XXXPXX-NH2, a bidirectional iterative synthesis and selection process was carried out. A completely different but active peptide sequence was identified (Ac-SVGPPH-NH2, IC50 = 165 nM). The two different hexapeptide sequences were prepared as linear homo- and heterodimer peptides in an attempt to improve the antigenicity. Of the four different sequences prepared, one heterodimer (Ac-STTSMMGGGSVGPPH-NH2) was found by ELISA to have a 10-fold improvement in activity over the two individual hexapeptides, and was equal to the inhibitory activity of the protein antigen. The equilibrium affinity constant of the MAb 12 toward this heterodimer sequence was 50-fold higher than the protein antigen when measured in a biosensor system. Since motifs from these two hexapeptides, namely, -STTS- and -GP-, were located in the primary sequence of the protein (residues 114-120, subtype ad), overlapping hexapeptides of this region were synthesized and assayed. The most active hexapeptide, namely, Ac-TTSTGP-NH2 (IC50 = 2.3 microM), was 10-fold less active than either hexapeptide found from the library. Extending the specific motif sequences to eleven residues resulted in an analog (Ac-STTSTGPSRTC-NH2) having an equilibrium affinity constant similar to the heterodimer. The combined use of positional scanning libraries and the iterative synthesis and selection process in this study illustrates the power of these methods for the identification of novel peptides that inhibit anti-protein antibodies. These methods can be directly applied to the development of improved immunodiagnostics.

Amino Acid Sequence↗
PubMedDate not supplied

[Isolation and long-term cultivation of rabbit embryonic stem cells].

A cell line similar to embryonic stem cells has been isolated from 5-day rabbit embryos. After the disruption of zona pellucida, embryos were mechanically separated into cel aggregates, which were then cultivated on a feeder layer of primary mouse embryonic fibroblasts. Cells similar to embryonic stem cells had high nuclear-to-cytoplasm ratio. It has been demonstrated for the first time that the inner cell mass and embryonic stem cells of rabbits expressed the activity of alkaline phosphatase. Between 10 and 30% of cells retained this expression and pluripotent characteristics up to the 23rd transfer. After 14-17 transfers the obtained embryonic cells could be induced to differentiation in vitro, which resulted in the formation of embryoid bodies. After the 23rd transfer, the line of rabbit embryonic cells was lost as a result of its differentiation.

Alkaline Phosphatase↗