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PubMed1993

Thyroglobulin glycosylation: location and nature of the N-linked oligosaccharide units in bovine thyroglobulin.

The cDNA sequence of bovine thyroglobulin (bTg) predicts 14 putative N-linked glycosylation sites. We have characterized the glycopeptides contained in a tryptic digest of bovine thyroglobulin in order to establish actual glycosylation sites. The distribution of oligosaccharide types within the known sites of N-linked glycosylation has also been examined. Each glycopeptide was subjected to neutral and amino sugar analysis, as well as sialic acid analysis. Thirteen of the 14 putative N-linked glycosylation sites in bTg were confirmed as glycopeptides in the mature protein. Nine of these confirmed glycosylation sites appear to bear complex or hybrid type oligosaccharide units and four contain oligosaccharide structures in which only mannose and glucosamine were seen. Complex or hybrid type glycosylation was confirmed at asparagine residues 91, 464, 476, 834, 928, 1121, 1757, 1851, and 2232, while oligosaccharides containing only mannose and glucosamine were found at asparagine residues 1346, 1995, 2104, and 2277. Analysis of the amino acid sequence in the region of each putative glycosylation site predicts a high probability of a beta turn at 10 of the 13 sites. While glycosylation was distributed through most of the length of the thyroglobulin sequence, no oligosaccharides containing only mannose and glucosamine were found in the N-terminal half of the molecule. Several of the glycosylated peptides showed microheterogeneity and occurred in two or more discrete peaks on HPLC. A single putative site at asparagine residue 179 was not recovered in the purified glycopeptide population.

Amino Acid Sequence↗

PubMed1984

Thyroglobulin structure-function: the effect of iodination on the structure of human thyroglobulin.

Thyroglobulin of very low iodine content has been prepared from a single non-toxic human goitre. The initial iodine content of the protein (0.038%) has been increased to levels of 0.16% and 0.85% by in vitro treatment with thyroid peroxidase and the resulting proteins studied with respect to their intrinsic fluorescence, circular dichroism spectra and binding of the hydrophobic probe 1,8-anilinonaphthalene sulfonic acid (ANS). While significant differences were observed between levels of iodination in both the ANS binding and intrinsic fluorescence of the thyroglobulin, no significant differences in the near and far UV circular dichroism spectra of the protein as a function of iodine content were observed. These data suggest that, the iodination of thyroglobulin effects specific areas of the protein without significant disruption of its overall secondary structure.

Chemical Phenomena↗

PubMed2005

Thyroglobulin antibodies in serum of patients with differentiated thyroid cancer: relationship between epitope specificities and thyroglobulin recovery.

BACKGROUND: Serum antibodies against thyroglobulin (TgAbs) are common in patients with differentiated thyroid cancer (DTC) and can interfere in thyroglobulin (Tg) assays. We identified the epitopes on Tg recognized by TgAb-positive sera from patients with DTC and examined the association between epitope specificity patterns and Tg recovery. METHODS: We tested 50 DTC sera for Tg epitope specificity, TgAbs, and Tg recovery. Epitope recognition was determined by use of a panel of 10 well-characterized Tg monoclonal antibodies directed against 6 Tg antigenic clusters (I-VI) in competitive reactions with test sera. Tg was measured by the Thyroglobuline IRMA (CIS bio international). Recovery of added Tg (TgREC) was determined by an in-house assay. RESULTS: Epitope recognition was restricted to immunodominant clusters in 58% of patients, whereas the rest were either broadly heterogeneous (16%) or nonreactive (26%). Median Tg recovery did not differ between sera with restricted and unrestricted specificities (69% vs 80%; P >0.05). TgREC was inversely correlated with the total number of epitopes recognized by sera (r = -0.66; P <0.001). CONCLUSIONS: TgAbs with both restricted and broad specificities are present in patients with DTC. TgAb interference is related to the number of epitopes recognized by sera rather than the pattern of epitope recognition.

Adolescent↗

PubMed1980

[Thyroglobulin-binding and anti-thyroglobulin antibody-secreting lymphocytes in human peripheral blood (author's transl)].

Human peripheral blood lymphocytes were studied with the use of fluorescinated human thyroglobulin (FITC-Tg) for the presence of cells which bind human FITC-Tg (Tg-BL) and which secrete a thyroglobulin antibody (Tg-SL) by culturing them for 5 days with pokeweed mitogen. In seven out of fifteen (47%) patients with Hashimoto's thyroiditis, an average of 0.18% of lymphocytes were able to bind FITC-Tg, while only one out of six (17%) patients with Graves' disease was able to bind them. No Tg-BLs were detected in five patients with miscellaneous autoimmune diseases and five normal subjects. Tg-BLs were identified as B lymphocytes by their inability to make rosettes with sheep red blood cells. Tg-SLs were detected in six out of eight (75%) patients with Hashimoto's thyroiditis and two out of five (40%) patients with Graves' disease. The positive rates of Tg-BL and Tg-SL were fairly well correlated with the thyroglobulin antibody titers.

Antibodies↗

PubMed1983

[The role of thyroglobulin carbohydrates in its hormone-liberating function. Proteolysis of deglycosylated thyroglobulin].

The proteolysis of thyroglobulin was performed after partial cleavage of its carbohydrate moiety. It was demonstrated that enzymatic removal of some thyroglobulin sialic acids results in increasing its resistance to proteolysis. Apparently, sialic acids are essential for maintaining an optimal thyroglobulin conformation for the action of proteases at hormonal biosynthesis from the reserve form.

Animals↗

PubMed1993

Monoclonal anti-idiotypic antibodies against human anti-thyroglobulin autoantibodies recognize idiotopes shared by disease-associated and natural anti-thyroglobulin autoantibodies.

Monoclonal murine anti-idiotypic antibodies generated against purified human anti-thyroglobulin (TG) antibodies from a patient with Hashimoto's thyroiditis recognized two major clusters of idiotopes (1C2 and 1B1) on human anti-thyroglobulin antibodies which were framework and paratope-related. A survey of affinity-purified autoantibodies from Hashimoto's patients indicated that the 1C2 and 1B1 idiotopes are expressed on the disease-associated anti-TG antibodies from several patients. 1C2 and 1B1 idiotopes are also detected on affinity-purified anti-TG antibodies isolated from serum of healthy donors and with therapeutic preparations of immunoglobulins obtained from plasma pools of healthy individuals. The observation that both framework and paratope-related idiotopes are shared by natural and patients' autoantibodies suggests that the anti-TG autoantibodies found in sera of patients with Hashimoto's disease represent an abnormal expansion of normal autoreactive B cell clones rather than the emergency of an antigen-driven, disease-specific B cell response.

Animals↗

PubMed1980

Immunohistochemical study of the C-cell complex of dog thyroid glands with reference to the reactions of calcitonin, C-thyroglobulin and 19S thyroglobulin.

Continued from the previous study in fetal animals (Kameda et al. 1980), the development and maturation of C-cell complexes in postnatal dogs from newborn to adult were investigated by use of an immunoperoxidase method using antisera to calcitonin, C-thyroglobulin (C-Tg) and 19S thyroglobulin, respectively. The younger the animals were, the more numerous were undifferentiated cells and high columnar epithelial cells in the complexes. With increasing age, the constituent elements of the complexes progressively differentiated. In one type of complex there are a large number of C-cells in various developmental stages, as well as undifferentiated cells and cysts. C-cell complexes composed mostly of mature C-cells were regarded as the more highly differentiated structures of this type. A second type contains follicular cells in various stages of differentiation in addition to undifferentiated cells and C-cells, i.e., 19S-positive cell masses not yet organized into follicles, primordial follicles with small lacunae and comparatively larger follicles. The follicular cells in the complexes were similar with respect to immunoreaction and folliculogenesis to the cells of fetal thyroids, but they developed very slowly. In conclusion, the present study indicates that follicular thyroid cells can differentiate within C-cell complexes, i.e., they develop from cells of ultimobranchial body origin.

Animals↗

PubMed1984

Unusual scarcity of restriction site polymorphism in the human thyroglobulin gene. A linkage study suggesting autosomal dominance of a defective thyroglobulin allele.

Chromosomal DNA prepared from 90 unrelated individuals, mainly of Caucasian origin, was screened for restriction fragment length polymorphisms in the 3' 220 kilobase pairs (kb) of the human thyroglobulin (Tg) gene. The probes used were Tg cDNA fragments and subcloned single-copy genomic segments, isolated from a human cosmid library. All in all, 1164 nucleotides were screened using 15 different restriction enzymes. The average number of nucleotides screened was 354 per individual. Only one polymorphism was found in these 1164 nucleotides, with a minor allele frequency of 2.2%. This polymorphism, which is located in an intervening sequence, was found in healthy individuals and in a family with hereditary congenital hypothyroidism due to a defect in the synthesis and structure of thyroglobulin. The Mendelian segregation of polymorphism and goiter in ten family members suggests that the rare variant is linked to a normal Tg allele and provides strong evidence for autosomal dominant inheritance of this Tg synthesis defect.

Base Sequence↗

PubMed2006

Effects of percutaneous laser ablation treatment in benign solitary thyroid nodules on nodule volume, thyroglobulin and anti-thyroglobulin levels, and cytopathology of nodule in 1 yr follow-up.

OBJECTIVE: To investigate the effects of ultrasound (US)-guided percutaneous laser ablation (PLA) in the treatment of benign solid hypoactive thyroid nodules on nodule volume, thyroid functions, nodule cytology and patients' complaints. MATERIAL AND METHOD: Criteria for enrollment in the study were as follows: patients with euthyroid, benign, hypofunctional nodule who had compressive symptoms or cosmetic complaints, but considered inoperable, or who rejected surgical treatment. PLA procedure at 3-5 watts (W) was applied to 15 thyroid nodules of 12 patients (4 male and 8 female; age range 20-78 yr, mean age 47.42+/-17.05 yr), and patients were followed up for 12 months. Thyroid functions and nodule volumes (ultrasonographically) were evaluated. US-guided fine needle aspiration biopsy (FNAB) was performed before and after the procedure, and biopsy specimens were cytologically evaluated. RESULTS: The mean nodule volume before the procedure was 11.97 ml (min-max 0.95-26.30 ml). However, 12 months after the procedure the mean nodule volume was 2.21+/-2.32 ml (min-max 0.10-7.65 ml). The mean reduction in nodule volumes was 82%. Thyroglobulin levels reached peak values at 1 month after the procedure, and anti-thyroglobulin levels at 3 months after the procedure. FNAB performed at 12th month showed neutrophil polymorphs, macrophages, abundant cell debris, colloid, multinucleated giant cells, and small fragments of fibrous stroma which indicated that PLA procedure led to degenerative changes in nodules. CONCLUSION: US-guided PLA is a new, successful treatment method which is reliable in the long term in benign solid thyroid nodules for selected patients who are inoperable or do not prefer surgery.

Adult↗

PubMed1987

A sensitive enzyme immunoassay for anti-thyroglobulin antibody using Fab'-horseradish peroxidase conjugate. Evaluation of in vitro anti-thyroglobulin antibody synthesis by lymphocytes from patients with autoimmune thyroid disease.

A sensitive enzyme immunoassay (EIA) for the detection of anti-thyroglobulin (Tg) antibodies was developed using Fab'-horseradish peroxidase (HRP) conjugate. Anti-Tg antibody was assayed by incubation with a thyroglobulin-coated polystyrene ball and then with affinity-purified anti-IgG Fab'-HRP conjugate. The HRP activity was assayed fluorimetrically. The sensitivity was 625 amol/tube and anti-Tg antibody levels between 0.5 and 200 ng/ml could be determined. The recoveries of anti-Tg antibody added to human sera at three different concentrations were 94.2-101.0%. Both within- and between-assay coefficients of variation were below 10%. Significant correlation was observed between values by the EIA and TGHA method (Kendall's rank correlation coefficient = 0.712, P less than 0.001). The present EIA for anti-Tg antibody is sensitive enough to determine anti-Tg antibody synthesized in vitro by the lymphocytes from patients with autoimmune thyroid disease and normal subjects. The amounts of anti-Tg antibody synthesized by peripheral lymphocytes from patients with Hashimoto's disease were significantly greater than those from patients with Graves' disease, although serum levels of anti-Tg antibody were usually elevated in both groups of patients. The results obtained suggest that anti-Tg antibody is synthesized in a different manner in patients with Hashimoto's disease and in patients with Graves' disease.

Adult↗

PubMedDate not supplied

Quantitative analysis of rat thyroglobulin messenger RNA in FRTL-5 cells by competitive polymerase chain reaction with human thyroglobulin messenger RNA.

To measure relative expression level of mRNA in a small number of cultured rat thyroid cells (FRTL-5), we developed a system of a quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay. Human thyroglobulin mRNA in total RNA extracted from a human thyroid tissue was used as an internal control. FRTL-5 cells in a 24 well dish were lysed with denaturing solution containing human RNA. Total RNA was extracted followed by reverse transcription and polymerase chain reaction. After digestion with a restriction enzyme, PCR products were separated by electrophoresis and stained with Sybr Green I, then their fluorescence was measured with fluorescent image analyser. Increase of thyroglobulin mRNA in FRTL-5 cells stimulated by thyroid stimulating hormone (TSH) was observed by this technique. Because this method does not require a large number of cells or radioactive isotopes, it is as useful for the analysis of the relative expression level of mRNAs in the cells as the conservative methods such as Northern Blot.

Animals↗

PubMed1983

Should one measure serum thyroglobulin in the presence of anti-thyroglobulin antibodies?

Thyroglobulin auto-antibodies (anti-Tg) may affect measurement of serum thyroglobulin (Tg). We have assayed sera for Tg by RIA regardless of presence or absence of anti-Tg, and this study was designed to assess the influence of anti-Tg on the results. Binding of human anti-Tg by the second antibody in our RIA (sheep anti-rabbit immunoglobulin) is very low and sera containing anti-Tg of varying titres do not systematically affect assay of Tg regardless of concentration. In our follow-up study of patients with thyroid cancer, correlation between clinical state and Tg concentration is greater than 97% whether anti-Tg is present or absent. These results indicate that in our assay anti-Tg positive sera do not need to be excluded.

Antibody Affinity↗

PubMed1975

Thyroglobulin messenger RNA: translation of a 33-S mRNA into a peptide immunologically related to thyroglobulin.

Poly(UC)--Sepharose chromatography of the RNA extracted from a thyroid fraction sedimenting between 800 X g and 27000 X g allows the purification of two RNA fractions amounting each to 1% of the applied material. The first one is loosely bound to the column from which it is eluted at 25 degrees C. It is mainly composed of 16-S and 12-S RNA comprising no poly(A) sequences. This could correspond to mitochondrial rRNA. The second one, which is eluted at 50 degrees C, is poly(A)-rich and represents 33-S and 17--18-S RNA species. The 33-S RNA resists heating at 80 degrees C, suggesting that it is composed of one polynucleotide chain. When injected into Xenopus oocytes, the 33-S RNA specifically promotes the synthesis of a peptide with an apparent molecular weight of 185000 and an apparent sedimentation coefficient of 10-S. This peptide is immunologically related to thyroglobulin and could represent its main precursor. Under the conditions tested it does not polymerize spontaneously into 19-S thyroglobulin, suggesting that assembly of the molecule could require specific, post-translational alterations of the precursor and/or the presence of additional lighter subunits.

Animals↗

PubMed1977

Concentration of thyroglobulin, iodine contents of thyroglobulin and of iodoaminoacids in human neonates thyroid glands.

The iodine and protein concentrations, the iodoamino acids content of thyroglobulin (TG) were determined in 17 thyroid tissues from human neonates who died from 3 hours to 47 days after birth. Total iodine concentration of neonate tissues increased with life duration. TG concentration was related to the survival duration of the neonates. Increase of the iodine content was associated to the increase of the TG content: mean value was 0.16 mug 127I/100 mug TG in neonates who died within the first 20 hours after birth, 0.25 mug in neonates who survived 26 to 72 hours and 0.43 mug in neonates living more than 10 days. Expressed as iodine content to total iodine ratio, iodoamino acid percentages were not related to the tissue. When the iodoamino acids were expressed in residues per molecule of TG, iodtyrosines, thyroxine and triiodothyronine increased with duration of survival. These variations in iodine content and concentration of thyroglobulin could be related to acute hormonal changes in serum observed in early neonatal period.

Humans↗

PubMed1995

Assay of thyroglobulin in serum with thyroglobulin autoantibodies: an unobtainable goal?

Measurement of thyroglobulin (Tg) in serum with anti-Tg autoantibodies (TgAb) represents a difficult challenge. Immunoradiometric assays (IRMA) employing monoclonal anti-Tg antibodies not cross-reacting with endogenous TgAb have recently been developed and proposed for Tg assays in TgAb-positive sera. The aim of the present investigation was to assess the clinical reliability of this approach. Assays of serum Tg in patients with and without TgAb using one such monoclonal antibody IRMA (Thyroglobulin IRMA-Pasteur; IRMA-1) were compared with those obtained by a conventional IRMA employing polyclonal anti-Tg antibodies (HTGK-Sorin; IRMA-2). Preliminary studies for assessment of the interference of TgAb showed that the recovery of added Tg was significantly higher (P < 0.01) when determined by IRMA-1 (64.6 +/- 23%) than by IRMA-2 (49.5 +/- 20%). Study groups included 79 patients with differentiated thyroid carcinoma (DTC) treated by total thyroidectomy and radioiodine ablation; 24 had no metastases or residual thyroid tissue, 31 had a thyroid residue, and 24 had metastatic disease. Seventy-five patients with autoimmune thyroid disease (47 with Graves' and 28 with Hashimoto's disease) were also included. In TgAb-negative sera from DTC patients, similar Tg concentrations were found by both IRMA, i.e. undetectable in most patients with no residual thyroid or neoplastic tissue, low to moderately elevated in the majority of those with residual thyroid tissue, and markedly elevated in all patients with metastatic disease. Serum Tg was undetectable by both assays in several TgAb-positive sera from DTC patients with residual thyroid tissue or metastatic disease, respectively, in whom a detectable or even high serum Tg concentration was expected. Despite the lower in vitro interference of TgAb in IRMA-1, there was no difference between the two assays. In the group of patients with thyroid autoimmune disease, serum Tg concentrations were found to be high in TgAb-negative sera and much lower in TgAb-positive sera by both IRMAs. In conclusion, the present study demonstrates that the use of a monoclonal antibody IRMA for serum Tg, although less susceptible to in vitro TgAb interference, does not necessarily provide any substantial advantage with respect to a conventional polyclonal IRMA in detecting Tg in TgAb-positive sera. The finding of undetectable or lower than expected serum Tg by either method in TgAb-positive serum may well reflect a truly reduced serum Tg concentration. This might be due to an accelerated Tg metabolic clearance in the presence of TgAb.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed2003

Recognition pattern of thyroglobulin autoantibody from hypothyroid dogs to tryptic peptides of canine thyroglobulin.

Circulating thyroglobulin autoantibody (TgAA) was analyzed using the Western immunoblot for determination of the dominant epitopes recognized by TgAA on tryptic peptides of canine thyroglobulin (cTg) in hypothyroid dogs. TgAA was measured in hypothyroid dogs, non-hypothyroid dogs with skin diseases and clinically normal dogs. Five of the 7 hypothyroid dogs, 1 of the 8 dogs with skin diseases and 1 of the 4 normal dogs were positive for TgAA. Four of the 5 TgAA-positive hypothyroid dogs were Golden Retrievers, and 3 of them showed high antibody titers. The sera of TgAA positive-dogs reacted to several peptides, and their patterns varied from sample to sample. Sera from 3 dogs with high titers of TgAA reacted broadly to high molecular weight peptides ranging from 45 to 90 kDa. These Western immunoblot patterns of the sera were disappeared after pretreatment with sufficient amount of intact cTg. All serum samples of both TgAA positive dogs and negative controls reacted to low molecular weight peptides ranging from 15 to 20 kDa. These immunoblot patterns of the sera were not disappeared even after pretreatment with sufficient amount of intact cTg. These findings show the possibility that the epitopes recognized by TgAA depend upon individual dogs with hypothyroidism and these autoantibodies recognize conformational epitopes on the cTg molecule.

Animals↗

PubMed1984

[Investigations on the mechanism(s) of the production of anti-thyroid hormone antibodies 3:Production of anti-rabbit thyroglobulin and anti-thyroid hormone antibodies in rabbits immunized with rabbit thyroglobulin].

Recently, the presence of anti-thyroid hormone antibodies has been reported in many cases of thyroidal and non-thyroidal disorders. In order to elucidate the immunological mechanism(s) in the production of anti-thyroid hormone antibodies, we immunized outbred rabbits and mice with different H-2 and Igh allotypes with human thyroglobulin (HTg) and showed that the production of both anti-HTg and anti-thyroid hormone antibodies is genetically controlled. In our present study, rabbit thyroglobulin (RTg) was purified from 4 rabbit thyroid glands and was immunized in two rabbits (RG-I, RG-2). The two rabbits were then serially bled and tested for the presence of anti-RTg and anti-thyroid hormone antibodies. In both rabbits, the production of anti-RTg and anti-thyroid hormone antibodies was observed. The binding constant of anti-RTg, anti-T4 and anti-T3 antibodies in RG-1 were 6 X 10(9)M-1, 9.5 X 10(8)M-1, 4.6 X 10(8)M-1, and those in RG-2 were 6.5 X 10(9)M-1, 5.6 X 10(8)M-1, 1.6 X 10(8)M-1, respectively. These results further strengthen the possibility that the antigen of the anti-thyroid hormone antibodies observed in various disorders so far reported is the HTg molecule. In addition, the fact that anti-RTg antibodies had a higher binding constant and capacity than anti-thyroid hormone antibodies suggests that the antigenic site(s) of RTg, which contains thyroid hormones, is not highly immunogenic.

Animals↗

PubMed1985

An enzyme linked immunosorbent assay (ELISA) for measurement of human serum thyroglobulin. Evaluation of the influence of thyroglobulin auto-antibodies.

The aim of the study was to develop an enzyme linked immunosorbent assay (ELISA) for measuring thyroglobulin (Tg) in human serum and to evaluate the influence of serum thyroglobulin auto-antibodies (TgAb) on the ELISA. The sensitivity of the ELISA was 2.1 micrograms/l. Serum Tg levels in healthy controls were from less than 2.1 to 55.5 micrograms/l (n = 46) (95% reference range). With serum Tg concentrations between 19.6 to 90 micrograms/l the within-assay coefficient of variation (CV) was from 4.5 to 6.6% (n = 12) and the between-assay CV from 8.5 to 10.5% (n = 6). The recovery from 20 to 89 micrograms Tg/l serum was from 93 to 101%. There was significant correlation between serum Tg concentrations measured by the ELISA and a RIA method in healthy controls (r = 0.85, n = 46, p less than 0.001) and in patients with differentiated thyroid carcinoma (r = 0.97, n = 28, p less than 0.001). The TgAb interfered with the serum Tg determination both in the ELISA and in the RIA method. The assay is simple and easy to perform, and the equipment is inexpensive and useful for large-scale serum Tg measurements as an alternative to RIA.

Adolescent↗