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N Scherberg

Publications and source records attributed to N Scherberg.

12 recordsLinked to original sources
PubMed1998

Induction of oral tolerance in human autoimmune thyroid disease.

Our laboratory has reported suppression of experimental autoimmune thyroiditis in mice by oral feeding with antigen. Based on these data, we considered it possible that oral feeding of animal thyroglobulin (TG) might induce tolerance to antigen in human autoimmune thyroid disease (AITD). Thirteen patients receiving thyroid hormone replacement with synthetic thyroxine (T4) (five patients with Graves' disease, treated with radioiodine 4 to 11 years ago and eight patients with Hashimoto's thyroiditis) were randomly assigned to a test group (switched to replacement with desiccated thyroid from porcine thyroids) and a control group (maintained on synthetic T4). Humoral and cellular immunologic parameters were evaluated in addition to clinical parameters before and every 3 months after the onset of study for a year. At the onset of study, there was no difference in clinical parameters, or humoral and cellular immunity to thyroid autoantigens, except a finding that one thyroid peroxidase (TPO) peptide (100 approximately 119) appeared to stimulate peripheral blood mononuclear cells (PBMC) during in vitro microproliferation assay more in the test group than control group (p = 0.051 by t test). Additionally, almost all of TPO and thyrotropin receptor extracellular domain (TSHR) peptides were slightly more stimulatory to PBMC from the test group than the control group, although this was not statistically significant. After treatment, all variables were analyzed at each time point between groups (t test), and also were analyzed over time in each group (analysis of variance, ANOVA). Among the clinical parameters, thyrotropin (TSH) levels were unchanged and equal. Total serum T4 levels (p < 0.05 at 6 and 12 months after treatment) and free thyroxine indices (FT4I) (p < 0.05 at all time points after treatment) were lower in the test group than the control group. This is an expected result of treatment with desiccated thyroid. We found no change over time nor any difference between groups at time points for titers of antibodies to thyroid autoantigens, ie, human TG, human TPO, and recombinant human TSHR from Escherichia coli. However, cellular immunity, measured by in vitro microproliferation of PBMC to peptides of TPO or TSHR, showed significant differences between groups. At 12 months, stimulatory indices (SI) of PBMC to six peptides, containing the indicated amino acids (764 approximately 95, 100 approximately 119, 110 approximately 129, 261 approximately 275, 441 approximately 448, 708 approximately 727) of 10 TPO peptides, and one peptide (145 approximately 163) of 14 TSHR peptides were lower in the test group than control group (p < 0.05). SI of PBMC to phytohemagglutinin, purified protein derivative from mycobacteria, and tetanus toxoid were not different between groups nor changed over time in any group. In conclusion, treating patients with AITD with an antigen related to the autoantigen TG did not produce changes in humoral immunity parameters, while cellular immunity to certain peptides were apparently suppressed. While the results are both surprising and intriguing, we need more evidence to justify the use of autoantigen as a form of immunospecific therapy in patients with AITD.

Administration, Oral↗
PubMed1997

Monoclonal antibodies to rat calcitonin: their use in antigenic mapping and immunohistochemistry.

A library of monoclonal antibodies (mAbs) to rat calcitonin (rCT) was raised from several fusions. Antibodies were screened by enzyme-linked immunosorbent assay with solid phase rCT. Affinities for rCT ranged from 10(9)-10(11) M(-1). Some mAbs reacted preferentially with solid phase rCT, but not with liquid phase, 125I-labeled rCT. Cross-reactivity with human CT (hCT) was assessed using solid phase hCT. Although there are only two amino acid differences, at least nine of the mAbs do not cross-react with solid phase hCT. Several cross-reactive mAbs were chosen for immunohistochemical studies of human medullary thyroid carcinoma samples and showed strong positive staining. A 33 x 33 matrix solid-liquid mAb inhibition assay was carried out to probe the rCT molecule. Five different clusters of mAb were distinguished and interpreted as reflecting five distinct antigenic regions on the surface of the rCT molecule.

Animals↗
PubMed1995

Does thyroidectomy, radioactive iodine therapy, or antithyroid drug treatment alter reactivity of patients' T cells to epitopes of thyrotropin receptor in autoimmune thyroid diseases?

The effect of treatment on thyroid antibody production and T cell reactivity to thyroid antigens was studied in 15 patients with Graves' disease (GD) before and after thyroidectomy, 19 patients with GD before and after radioactive iodine (RAI) therapy, and 9 patients maintained euthyroid on antithyroid drugs (ATD). Twenty subjects matched for age and sex without known thyroid disease served as controls. In GD patients, the responses of peripheral blood mononuclear cells (PBMC) and TSH receptor (TSHR)-specific T cell lines to recombinant human TSHR extracellular domain, thyroglobulin, and TSHR peptides were examined on the day of surgery or RAI therapy (day 0) and also 6-8 weeks and 3-6 months thereafter. Reactivity to TSHR peptides before surgery was heterogeneous and spanned the entire extracellular domain. Six to 8 weeks after subtotal thyroidectomy, the number of patients' PBMC responding to any peptide and the average number of recognized peptides decreased. A further decrease in the T cell reactivity to TSHR peptides was observed 3-6 months after surgery. The responses of PBMC from Graves' patients before RAI therapy were less than those in the presurgical group. Six to 8 weeks after RAI therapy, the number of patients responding to any peptide and the average number of recognized peptides increased. Three to 6 months after RAI, T cell responses to TSHR peptides were less than those 6-8 weeks after RAI therapy, but still higher than the values on day 0. Responses of PBMC from patients with GD, maintained euthyroid on ATD, were lower than those before surgery or RAI therapy. The reactivity of T cell lines in different groups reflected a pattern similar to PBMC after treatment. TSHR antibody and microsomal antibody levels decreased after surgery, but increased after RAI therapy. The difference in the number of recognized peptides by patients' PBMC before RAI and surgery may reflect the effect of long term therapy with ATD in the patients before RAI vs. the shorter period in patients before surgery. The decreased T cell reactivity to thyroid antigens after thyroidectomy could be the result of removal of a major part of the thyroid gland or redistribution of suppressor-inducer T cells. The increased T cell response after RAI therapy is probably epitope specific, rather than a response to the whole TSHR molecule. Synchronous recognition of peptides 158-176 and 248-263 is important for the development of GD, and the loss of recognition of one of these epitopes may be an early sign of immune remission and a predictor of euthyroidism.

Adult↗
PubMed1992

Site-specific incorporation of [125I]iododeoxyuridine into DNA.

A procedure for the incorporation of [125I]IdU into specific sites in DNA is described. The approach depends upon attachment of radioiododeoxyuridine to a controlled pore glass support which is then used for automated synthesis of an oligomer. The resulting oligomer, containing a terminal 3'[125I]iododeoxyuridine, is used as a primer during DNA synthesis catalyzed by the Taq polymerase employing thermal cycling. The product formed includes the radioiodonucleotide at a single internal site determined by the length of the oligomer.

Base Sequence↗
PubMed1992

Differential elimination of radioiodine from single- and double-stranded 125I-DNA.

[125I]Iododeoxyuridyl residues in heat-denatured I-DNA underwent deiodination in solutions of sodium bisulfite. In 0.5 M bisulfite containing 1 M trimethylamine, 92% of the iodine was released from denatured DNA in 2.5 min at 60 degrees C. By contrast iodine in native I-DNA remained stably bound under the same condition. The deiodination of [125I]I-deoxyuridine residues incorporated by enzymatic copying of oligomers 60 nucleotides in length was found to be pairing dependent. While 125I in iododeoxyuridine paired to deoxyadenosine in a complementary oligomer remained approximately equal to 90% covalently bound in the presence of 1 M bisulfite at 60 C, when the iodouridylate residue was mismatched greater than 96% was eliminated in 4 min. The presence of mismatches in the two nucleotides adjacent to a [125I]iododeoxyuridine/deoxyadenosine pair increased the elimination of iodine. The results indicate that the deiodination reaction might be applied for the rapid detection of variations in natural DNA sequences.

DNA↗
PubMed1986

Translational control of insulin biosynthesis. Evidence for regulation of elongation, initiation and signal-recognition-particle-mediated translational arrest by glucose.

The biosynthesis of insulin in the islets of Langerhans is strongly controlled at the translational level by glucose. We have used a variety of experimental approaches in efforts to dissect the mechanisms underlying the stimulatory effect of glucose. To assess its effects on rates of peptide-chain elongation, isolated rat islets were labelled with [3H]leucine at different glucose concentrations in the presence or absence of low concentrations of cycloheximide. Under these conditions, at glucose concentrations up to 5.6 mM, endogenous insulin mRNA did not become rate-limiting for the synthesis of insulin, whereas stimulation of non-insulin protein synthesis was abolished by cycloheximide at all glucose concentrations, indicating either that insulin synthesis is selectively regulated at the level of elongation at glucose concentrations up to 5.6 mM, or that at these concentrations inactive insulin mRNA is transferred to an actively translating pool. Glucose-induced changes in the intracellular distribution of insulin mRNA in cultured islets were assessed by subcellular fractionation and blot-hybridization using insulin cDNA probes. At glucose concentrations above 3.3 mM, cytoplasmic insulin mRNA was increasingly transferred to fractions co-sedimenting with ribosomes, and relatively more of the ribosome-associated insulin mRNA became membrane-associated, consistent with effects of glucose above 3.3 mM on both the initiation of insulin mRNA and SRP (signal recognition particle)-mediated transfer of cytosolic nascent preproinsulin to the endoplasmic reticulum. When freshly isolated islets were homogenized and incubated with 125I-Tyr-tRNA, run-off incorporation of 125I into preproinsulin was increased by prior incubation of the islets at 16.7 mM-glucose. The addition of purified SRP receptor increased the run-off incorporation of [125I]iodotyrosine into preproinsulin, especially when the islets had been preincubated at 16.7 mM-glucose. These findings taken together suggest that glucose may stimulate elongation rates of nascent preproinsulin at concentrations up to 5.6 mM, stimulates initiation of protein synthesis involving both insulin and non-insulin mRNA at concentrations above 3.3 mM, and increases the transfer of initiated insulin mRNA molecules from the cytoplasm to microsomal membranes by an SRP-mediated mechanism that involves the modification of interactions between SRP and its receptor.

Animals↗
PubMed1977

Iodination-deiodination. A radiochemical method for detection of structure and changes in structure in RNA.

Bound iodine is released from radioiodinated nucleotides in polymers exposed to sodium bisulfite. The rate of bisulfite-catalyzed deiodination of pyrimidines can be controlled both by change of temperature of pH and is also dependent on the molecular association of the nucleotide. The rate of release of iodine from iodocytidine in polycytidylate is greater than the rate of elimination from RNA. Experiments testing the influence of base-pairing of the iodopyrimidines in synthetic polynucleotides showed that pairing of the substituted nucleotide protected the iodine bond. The rates of bisulfite-catalyzed deiodination of several radioiodinated RNAs were measured. The action of bisulfite on all single stranded RNAs tested was multiphasic consisting of a rapid early deiodination reaction supplanted by a slower phase which was followed by reacceleration of release. The release of iodine from double stranded RNA and DNA-RNA duplexes was retarded in comparison with the release from ribosomal and messenger RNA fractions. The deiodination profiles of single and double stranded RNA suggested that the intermediate stage iodine release is governed by melting of paired zones of low stability. Late release may result from destablization of the molecule through the addition of bisulfite to the pyrimidine ring or deamination. The effect of several substances expected to complex with polynucleotides was tested. Acridine orange and ethidium bromide increased loss of iodine from ribosomal RNA but slightly decreased elimination from double stranded viral RNA. A basic protein fraction isolated from ribosomal particles accelerated the deiodination of ribosomal RNA. While the destabilization caused by this protein fraction was greater than that caused by an equal amount of albumin, as tested the effect was non-specific. The results show that a change in sensitivity to chemical deiodination may folow the interaction of small amounts of protein with polynucleotides.

Animals↗