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C Sidman

Publications and source records attributed to C Sidman.

11 recordsLinked to original sources
PubMed1999

Hypothalamic beta-endorphin concentrations are decreased in animals models of autoimmune disease.

Complex interactions between the neuroendocrine and the immune systems are present in autoimmune diseases. The central opioid peptide beta-endorphin (BE) has been shown to modulate peripheral immune responses in normal animals. In the present study we analyze the hypothalamic concentrations of this peptide in two models of spontaneous autoimmune disease, the MRL [corrected] lpr/lpr mouse, that develops a lupus-like autoimmune disease, and the obese strain (OS) chickens afflicted with spontaneous autoimmune thyroiditis. In both instances, hypothalamic concentrations of BE are significantly lower than normal controls. In MRL [corrected] lpr/lpr mice, BE is already lower at 1 month of age, when no clinical sign of the disease is yet present. Similarly, low levels of BE are observed in OS chickens before the onset of thyroiditis, i.e., already at the embryonic stage. Moreover, a further decrease of BE is observed in OS chickens in correspondence with the first signs of thyroid mononuclear infiltration. Considering the immunosuppressive effects exerted by central BE, these results are suggestive of the fact that in autoimmune disease prone animals the low hypothalamic concentrations may be one of several factors predisposing for the development of autoimmune disease.

Animals↗
PubMed1992

Targeted disruption of the mouse transforming growth factor-beta 1 gene results in multifocal inflammatory disease.

Transforming growth factor-beta 1 (TGF-beta 1) is a multifunctional growth factor that has profound regulatory effects on many developmental and physiological processes. Disruption of the TGF-beta 1 gene by homologous recombination in murine embryonic stem cells enables mice to be generated that carry the disrupted allele. Animals homozygous for the mutated TGF-beta 1 allele show no gross developmental abnormalities, but about 20 days after birth they succumb to a wasting syndrome accompanied by a multifocal, mixed inflammatory cell response and tissue necrosis, leading to organ failure and death. TGF-beta 1-deficient mice may be valuable models for human immune and inflammatory disorders, including autoimmune diseases, transplant rejection and graft versus host reactions.

Animals↗
PubMed1991

Optimization of binding capacity and specificity of protein G on various solid matrices for immunoglobulins.

Streptococcal protein G is a more versatile and efficient alternative to staphylococcal protein A in purifying immunoglobin G (IgG) isotypes from various animal species. Optimizations are most dramatic with goat IgG, which binds protein G 55 times better than protein A. Using GammaBind G (a recombinant form of protein G (Genex Corp.)), we optimized binding capacity and specificity for IgG. Protein G was covalently coupled to three different matrices (CNBr-Sepharose, Tresyl-Sepharose, and Affigel-10) and compared with protein A-CNBr-Sepharose. Equal volumes of human, mouse, and goat serum samples were equilibrated into Hepes/NaOH buffers with various ionic strengths (i.e., concentrations of NaCl) and pH values and allowed to bind to affinity columns of proteins G and A. Bound ligands were eluted with 8.0 M urea, 0.05-M Tris/HCl, pH 8.00. Bound fractions were assayed for protein concentration and analyzed by sodium dodecyl sulfate polyacrylamide electrophoresis. The optimal conditions for binding IgG to protein G are 1.0 M NaCl and pH 8.0 for human, mouse, and goat.

Animals↗
PubMed1981

Roles of protein and carbohydrate in glycoprotein processing and secretion. Studies using mutants expressing altered IgM mu chains.

The role of specific structural elements in glycoprotein metabolism and secretion was studied using the IgM mu chains from normal and mutant hybridoma cell lines. Five classes of altered mu chains were studied, all of which lacked various portions of the normal protein sequence, and three of which had one and the others two fewer carbohydrate units than wild type mu. One mutant secreted mu chains more rapidly than wild type cells. Two of the mutant cell lines secreted very little IgM, and both of these degraded intracellular mu chains at an abnormally high rate. Tunicamycin largely blocked IgM secretion in wild type and three mutant cell lines, but caused less inhibition in the two other mutant lines. When glycosylation in the two low secreting mutants was blocked by tunicamycin, degradation of mu chains was substantially reduced in one but unaffected in the other. All of the above properties were retained by the altered mu chains when the mutants were further hybridized with cells producing wild type mu. Overall, the various carbohydrate units and polypeptide sequences seem to play different roles in a single protein's metabolism and expression. The carbohydrate moieties may exert independent effects on protein degradation and on secretion.

Animals↗
PubMed1981

Differing requirements for glycosylation in the secretion of related glycoproteins is determined neither by the producing cell nor by the relative number of oligosaccharide units.

Previous reports, using a variety of myeloma cell lines and activated normal B cells, have shown that different classes of immunoglobulins have different carbohydrate requirements for secretion. Thus, secretion of IgM and IgE was almost totally blocked by the antibiotic tunicamycin, secretion of IgA was partially inhibited, and secretion of IgG was essentially unaffected (Hickman, S., Kulczycki, A., Jr., Lynch, R. G., and Kornfeld, S. (1977) J. Biol. Chem. 252, 4402-4408; Hickman S., (1978) J. Immunol. 121, 990-996). Here, similar experiments using hybridoma cell lines secreting IgM and IgG or IgD are reported. Tunicamycin prevented the majority of IgM secretion but did not affect IgG secretion in cells producing both isotypes. This shows that the differential effects of tunicamycin on IgM and IgG secretion are due to factors intrinsic to the respective heavy chain polypeptides themselves, rather than to other properties of the producing cells. The secretion of IgD, which is as heavily glycosylated as IgM, was not inhibited by tunicamycin. Thus, the simple degree of immunoglobulin heavy chain glycosylation does not determine the extent of the requirement for glycosylation in the secretion of that isotype.

Animals↗
PubMed1981

B lymphocyte differentiation and the control of IgM mu chain expression.

The biosynthesis of IgM mu polypeptides was studied in isolated populations of normal B lymphocytes and in various IgM-producing cell lines. Membrane and secretory mu were found to be distinct polypeptide species, with separate biosynthetic intermediates from the translation stage onwards. Various B cell populations express different portions of the two biosynthetic mu pathways. Normal, resting small B lymphocytes do not secrete detectable mu and lack the ater intermediate forms of secretory mu. However, they apparently possess, and translate, secretory mu mRNA, and show earlier secretory mu intermediate protein forms. Resting B cells thus exert posttranslational control over secretory mu expression. Since the later intermediate forms of secretory mu, which are lacking in small B cells, are due to carbohydrate modifications of the mu chain, it is suggested that the carbohydrate portion may be involved in regulating the expression of the secretory mu glycoprotein. In contrast to small B cells, highly differentiated IgM-secreting cells control the expression of membrane mu by a pretranslational mechanism.

Animals↗
PubMed1981

The role of DNA rearrangement and alternative RNA processing in the expression of immunoglobulin delta genes.

We have established the exon-intron structure of the gene coding for the constant (C) region of the mouse immunoglobulin delta heavy chain, using DNA clones isolated from BALB/c embryos and the delta mRNA extracted from two delta-producing hybridomas, B1-8. delta 1 and GCL2.8. At least three types of C delta gene structures are identified. A 2.7 kb delta mRNA reveals six exons. This delta mRNA may code for a membrane-bound delta chain. A second delta mRNA of 1.8 kb shares the first (5' side relative to direction of transcription) three exons with the 2.7 kb delta mRNA and in addition contains a fourth exon unique to this mRNA species. This delta mRNA most likely codes for a secreted delta chain. A third delta mRNA, also of 1.8 kb, shares the first four exons and a part of the fifth exon with the 2.7 kb mRNA. Its function, if any, remains unclear. We investigated the question of how a lymphocyte can produce the mu and delta heavy chains simultaneously, using the hybridoma GCL 2.8, which makes both IgM and IgD. Results of Southern gel blot analysis and gene cloning experiments indicate that this cell utilizes the same rearranged VH gene for the synthesis of the mu and delta chains, and yet maintains the embryonic configuration for the C mu and C delta genes and for the intervening region. Based on these results, we conclude that the VH sequence is spliced alternatively to the C mu or C delta sequence during processing of the primary RNA transcript. An alternative mechanism for the expression of the delta gene is found in hybridoma B1-8. delta 1, which actively secretes delta chains and synthesizes no mu chain. This mechanism involves deletion of the C mu gene, which brings the complete VH gene closer to the C delta gene.

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