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G Spira

Publications and source records attributed to G Spira.

At least 37 records · Page 2Linked to original sources
PubMed1992

Involvement of different S4 parts in the voltage dependency of Na channel gating.

Three synthetic peptides corresponding to parts of S4 of the first repeat of eel electroplax sodium channel were synthesized. The basic peptide was C1+ which corresponds to amino acids 210-223 (eel channel numbering) and two subfractions: an external fraction, C1+ex (amino acid 210-217); and an internal part, C1+in (amino acid 218-221). Peptide C1+ includes four of the charged amino acids of this domain; peptide C1+ex includes three of the charged amino acids and is closer to the external membrane surface (according to channel models) than peptide C1+in which includes the fourth charged amino acid alone. Antibodies generated in rabbits against these peptides were shown to be site specific. Using the whole-cell patch-clamp technique, we found that in rat dorsal root ganglion (DRG) cells, the antibodies against C1+in but not against C1+ex had an effect on the gating parameters. They shifted the Na-channel inactivation curve towards hyperpolarization and decreased the slope of the Na-channel activation curve. These results demonstrate that during the conformational changes associated with channel gating, the fourth charged amino acid of S4 must be accessible to antibodies given to the external solution. Furthermore, they indicate a specific involvement of S4 in the voltage dependency of the gating processes.

Amino Acid Sequence↗
PubMed1992

Depolarization exposes the voltage sensor of the sodium channels to the extracellular region.

Two domains of Na channels were mapped with site-specific antibodies raised in rabbit against synthetic peptides corresponding to a part of the voltage sensor of internal repeat 1-C1+ (amino acids 210-223) and to a region designated dipole (amino acids 1690-1699) of eel electroplax sodium channels. The antibodies bind to their respective domains in both purified and membrane-bound channels and immunoprecipitate the channels from eel electroplax and rat brain synaptosomes. Anti-C1+ depresses the action potential of rat sciatic nerve in a concentration-dependent way. It binds to the external side of rat brain synaptosomal vesicle, and its binding is potentiated by depolarization. Anti-dipole binds to the inner side of the vesicle, and the binding is inhibited by depolarization.

Action Potentials↗
PubMed1991

High plasma fibronectin levels in multiple myeloma patients: possible mechanisms and clinical implications.

Fibronectin (FN) has been implicated in the formation of cryoprecipitates in rheumatic diseases and is present in tissues where, under pathological conditions, immune complexes are frequently deposited. We found elevated levels of FN in the plasma of 92% of multiple myeloma patients tested compared with a group of normal subjects, although the level of FN did not correlate with the level of the paraprotein. We then characterized the interacting fragments on both molecules and found that under physiological conditions of pH and ionic strength both heavy and light chain of all multiple myeloma and normal IgG showed affinity to FN; the active fragment on FN was found to be the aminoterminal heparin-binding domain. These findings raise the possibility that FN might be implicated in some of the clinical symptoms of multiple myeloma.

Antibody Affinity↗
PubMed1988

T15 PC-binding monoclonal antibodies retain specificity when they switch from IgM to IgG.

The expression of some Ag-binding sites and their associated H and L chain V region genes are often dominated by one or another of the IgG subclasses. This is true of T15 anti-phosphorylcholine (PC) response in which the dominant T15 H (V1, DFL11.6 JH1) and L (VK22, JK5) chain V regions are seldom found associated with the gamma 2b or gamma 2a C regions in the circulation of BALB/c mice. In the present study we describe the characterization of gamma 2b, gamma 2a, and gamma 1 anti-PC antibodies obtained from IgM-producing hybridomas by Ig switching in culture. All switch variants retained the parental T15 idiotype, PC binding, and fine specificity. We thus conclude that the apparent in vivo restriction on the expressed T15 PC binding gamma 2 antibodies is not due to a conformational limitation on the expression of the anti-PC T15 binding site. Further, these studies confirm that in vitro switching can be used to generate mAb that are not readily available in vivo.

Animals↗
PubMed1987

Immunoglobulin synthesis in myelodysplastic syndromes: normal B-cell and immunoregulatory T-cell functions.

Peripheral blood cells from patients with myelodysplastic syndromes were assayed for B-cell and immunoregulatory T-cell functions. The B/T cell ratio in myelodysplastic patients (n = 11) was significantly higher than in controls (n = 12). These patients had a reduction in total T-cell (OKT3+) frequency and in T-cell subset (OKT4+/OKT8+) ratios. The response of patients' cells to both pokeweed mitogen (PWM) and phytohemagglutinin (PHA) was reduced, but patients' B cells responded normally to stimulation with Staphylococcus aureus Cowan (SAC). The levels of IgG and IgM detected in 7-day culture supernatants of PWM-stimulated patient and control cells were similar. Normal B-cell and immunoregulatory T-cell functions were subsequently demonstrated in allogeneic co-culture combinations of enriched T and B cells from patients and controls. The data presented indicate that the frequent infections of myelodysplastic patients are not causally related to impaired humoral mechanisms. The data also favor the possibility that the stem cell disorder in these syndromes is functionally expressed at a subsequent stage to the lymphoid differentiation pathway.

Antibody Formation↗
PubMed1987

Mapping a region associated with Na channel inactivation using antibodies to a synthetic peptide corresponding to a part of the channel.

Antibodies to the synthetic peptide (carrier-coupled) corresponding to amino acids 210-223 of the primary sequence of eel Na channel (C1+ peptide) were generated. The antipeptide antibodies were used to identify functional roles as well as the accessibility from the external membrane surface of the C1+ domains. Rabbit antipeptide antibodies bound specifically to the C1+ synthetic peptide and to an eel membrane fraction bearing a high density of Na channels. When applied to the external surface of cultured dorsal root ganglion cells obtained from newborn rats, the antibodies modify Na channel inactivation by shifting the steady-state Na current-inactivation parameter, h infinity, curve to more negative potentials in fast and slow Na currents. The rate of inactivation of the slow channel is shown to be increased. The antibodies do not have a significant effect on activation of the channels. Part of the amino acid sequence corresponding to C1+ peptide is therefore accessible, in the mammalian Na channel, from the external membrane surface and is associated with the inactivation gate.

Action Potentials↗
PubMed1986

Impaired immunoglobulin synthesis in multiple myeloma: a B-cell dysfunction.

Peripheral blood samples collected from normal individuals and patients with benign monoclonal gammopathy and multiple myeloma were separated and assayed for their T- and B-cell subpopulations as well as immunoglobulin (IgG, IgM) synthesis in vitro. To rule out any functional or quantitative alterations related to therapy, only newly diagnosed multiple myeloma patients and subjects with benign monoclonal gammopathy were included in our study. Multiple myeloma patients were further subdivided into two groups. Group A consisted of patients with low and intermediate tumor burdens, while group B included patients with high tumor mass. B- and T-cell subset analysis revealed an abnormal ratio between B/T and OKT4+/OKT8+ lymphocytes compared to healthy controls. These alterations were especially prominent in group B multiple myeloma. Immunoglobulin synthesis was studied in pokeweed-mitogen-stimulated lymphocyte cultures. The results indicate that the failure to synthesize and secrete immunoglobulin resides within the B-cell lineage and is probably due to a functional B-cell defect. T-cell immunoregulatory functions seem to be unaffected in both multiple myleoma and benign monoclonal gammopathy patients.

B-Lymphocytes↗
PubMed1986

[Determination of rotational defects of the femur by computer tomographic determination of the antetorsion angle of the femoral neck].

The first of all unexplained but persisting static complaints after femoral fractures are due to rotational deformities. The clinical examination can only sustain the suspicion of a rotational deformity but can not determine its exact extent. The usual X-ray determination of the anteversion angle in the technique of Dunn and Rippstein as a measure for torsional deformities is often very difficult, because of the exact positioning conditions of patients with posttraumatic axial deformities, soft tissue contractures and painful motility restrictions. With the total body computertomography we have a safe and quick technique, independent of the patient's positioning, to determine the anteversion angle without problems. In comparing the two sides, the rotational deformity can be recognized and its extent can exactly be measured. Because of the simple technique and the exact determination of rotatory deformity a computertomographic measuring of the anteversion of the femoral head always should be made before planning a corrective osteotomy to fix the extent of correction, whenever a total body scan is available.

Adult↗
PubMed1985

Isolation and characterization of anti-monosialoganglioside monoclonal antibody 19-9 class-switch variants.

Three different monoclonal antibody isotypes, IgG1, IgG2b, and IgG2a, were derived by selection of isotype-switch variants from the CO-19-9 hybridoma. All three antibodies retained their binding specificities and affinities and bound to the same epitope--as defined by the anti-idiotype analysis. Availability of gamma 1, gamma 2b, and gamma 2a Ig heavy chain variants directed against the same epitope on the monosialoganglioside antigen permitted detailed analysis of their Fc fragment receptor (FcR) binding affinities, their cytolytic activities (antibody-dependent, macrophage-mediated cytotoxicity) in vitro, and their tumoricidal activities in vivo. Analysis of the binding of three isotypes to the human FcR expressed by U937 cells induced by gamma interferon has shown that only IgG2a proteins bound to high-affinity FcR, but not IgG1 or IgG2b variants. Although all three isotypes were active in the antibody-dependent, macrophage-mediated cytotoxicity assay with murine thioglycolate-elicited macrophages, the IgG2a gave the highest percentage of lysis; similar results were obtained in the same assay with human monocytes as effector cells. In the nude mice experiment, only the IgG2a variant inhibited growth of human colorectal carcinoma, while IgG1 and IgG2b were ineffective. Thus, selection of isotype-switch variants resulted in the conversion of monoclonal antibody from noncytolytic to cytolytic with possible immunotherapeutic application.

Animals↗
PubMed1985

Serum immunoglobulin-lipid complexes in plasma cell dyscrasia.

Immunoglobulin-lipid complexes (SILC) are found in the serum of all patients with monoclonal gammopathy. Fractionation by density gradient ultracentrifugation, Sephadex G-200 chromatography and Sepharose protein A affinity, followed by extensive immunoassaying for immunoglobulins and lipoproteins, does not confirm the accepted assumption that SILC are immune complexes between monoclonal immunoglobulins and lipoproteins. Lipid extraction of monoclonal fractions isolated on protein A columns followed by thin-layer chromatography shows a lipid pattern characteristic of the one found in cellular membranes. It is proposed that SILC are hydrophobic complexes between immunoglobulins and lipids, as described in membranes of B lymphocytes.

Chromatography, Gel↗
PubMed1984

The identification of monoclonal class switch variants by sib selection and an ELISA assay.

Monoclonal antibodies can now be generated against a wide variety of antigens. However, a potentially useful monoclonal antibody may be of the wrong class or subclass for a particular task. Antibodies of the desired class can be obtained by identifying rare subclones in which the variable region has been rearranged to a new constant region. We describe here the use of sib selection and an enzyme-linked immunoassay (ELISA) for isolating such class and subclass switch variants from 2 IgM and 1 IgG3 producing hybridoma. The relative simplicity of ELISA assays makes it feasible to apply this approach to many different hybridomas. Since commercial affinity purified class and subclass specific antibodies are now available, the method can be used by any laboratory. Furthermore, the technique does not require that the switch variants express surface immunoglobulin and enriches for hybridomas secreting higher amounts of antibody.

Animals↗
PubMed1984

Plasma cholesterol concentration and extra lipid band in monoclonal gammopathies.

Plasma lipids and lipoproteins were studied in 21 patients with benign monoclonal gammopathy, 21 patients with multiple myeloma and seven patients with Waldenström's macroglobulinaemia. Results were compared with those of a control group, age and sex matched. Low plasma cholesterol levels in all three patient groups were associated with low HDL-cholesterol concentrations. Apo A-I, but not apo B, was significantly reduced. Sixty per cent of the patients exhibited an extra lipid band on plasma lipoprotein electrophoresis, which could be an immunoglobulin-lipid complex. In these patients plasma and LDL-cholesterol levels were significantly lower than in those patients in whom this band was absent. No correlation was found between the severity of the disease and plasma lipid pattern.

Aged↗
PubMed1984

[Localization of enlarged parathyroid glands in hyperparathyroidism. Experiences with and role of computed tomography].

40 patients with primary hyperparathyroidism, 2 with and 38 without previous surgery had computed tomography (CT) and ultrasonography (US) preoperatively. CT correctly identified enlarged glands in 75%, US in 80%. In 7.5% US was correctly negative. In 12.5% CT has shown only a correct suspicion. Us was false positive in 2.5%, CT in 5%. US was false negative in 10%, CT in 7.5%.

Female↗
PubMed1983

Detection of IgD 'hidden' lambda light chain.

Immunoelectrophoresis and immunodiffusion of some IgD myeloma proteins fail to demonstrate precipitin bands between the light chain and anti-light chain serum. Reduction and alkylation of purified IgD preparation was found to render the molecule reactive to anti-lambda serum. Iodinated IgD myeloma protein was successfully precipitated by both anti-delta and anti-lambda antibodies. Both antisera precipitated heavy and light chains of a MW of 70,000 and 24,000 daltons respectively. In addition, a band of 39,000 daltons was also evident. Reduction and alkylation of the iodinated molecule, followed by precipitation with anti-delta serum demonstrated only the 70,000 and 39,000 daltons bands. The present report indicates that by sensitive techniques, such as iodination and immunoprecipitation, non-reactive hidden light chains can be detected in IgD lambda molecules.

Electrophoresis, Polyacrylamide Gel↗
PubMed1983

Primary sclerosing cholangitis associated with immunodeficiency.

An infant, first admitted at the age of 5 months with diarrhea (which was adequately treated with formula), was readmitted at the age of 1 year with poor weight gain, steatorrhea, and hepatomegaly. Liver function test results were compatible with cholestatic jaundice, and hepatobiliary scintigraphy visualized dilated bile ducts and evidence of hepatocellular disease. Exploratory laparotomy, liver biopsy, and cholangiography disclosed pathologic and roentgenographic findings of primary sclerosing cholangitis (PSC). The patient proved to be immunodeficient, pointing to the possible pathogenetic role of immunodeficiency in causing PSC in some patients. It is important to look for the disease in immunodeficient children and in patients with ulcerative colitis, and to consider PSC in the differential diagnosis of cholestatic jaundice.

Bile Ducts↗
PubMed1983

Low-molecular-weight (61K) mu chain in P3HR-1 cells and various derived somatic hybrids.

The expression of a truncated 61K mu chain in the Burkitt lymphoma lien P3HR-1 and a derived ouabain and TG-resistant subline, PUT, and in various somatic cell hybrids with PUT as one of their parents is described. Both PUT and P3HR-1 contain intracellular mu and kappa chains, but express no membrane immunoglobulin. Immunoprecipitation of 14C-labeled amino acid or [3H]glucosamine-labeled P3HR-1 extracts with anti-mu serum brought down the same 61K mu chain. Anti-light-chain sera did not precipitate the truncated mu chain. P3HR-1 is a clonal derivative of the Burkitt lymphoma (BL) line Jijoye. The parental Jijoye line is membrane-IgM positive and contains two normal-sized mu chains. Both are precipitable by anti-mu and anti-kappa sera. In addition, anti-mu also precipitated a 61K mu chain. A 61K mu chain was also identified in the following somatic hybrids: PICATPO, an autohybrid of two different P3HR-1 sublines, PUTRAL and PUT/ARH-77, derived from the fusion of PUT with the membrane-IgG-positive BL line Rael and the lymphoblastoid cell line (LCL) ARH-77, respectively, and the HP-1 (PUT/HL-60) hybrid, derived from the fusion of PUT with the granulocytic leukemia line, HL-60. The 61K mu chain could not be detected in some other BL/BL hybrid combinations, namely RAMPUT (PUT/Ramos) and NAMPUT (PUT/Namalva). The anti-light-chain serum (lambda or kappa) had no detectable effect on the truncated 61K mu chain in any of the cases tested, suggesting a lack of assembly between the 61K mu chain and the light chain.

Cells, Cultured↗