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Biomedical subjects

N Amino

Publications and source records attributed to N Amino.

At least 271 records · Page 15Linked to original sources
PubMed1986

Radioreceptor assay of anti-TSH receptor antibody activity: comparison of assays using unextracted serum and immunoglobulin fractions, and standardization of expression of activities.

A radioreceptor assay for TSH receptor antibodies developed by Shewring and Smith is described in which unextracted serum is used. The assay is simple and reproducible. TSH-binding inhibitor immunoglobulin (TBII) activity determined using unextracted serum correlated well with that determined using the immunoglobulin fraction purified with polyethylene glycol. The assay detected TSH receptor antibodies in 81 of 85 patients (95%) with untreated Graves' disease, no patients with Graves' disease in remission, and 7 of 57 patients (12%) with Hashimoto's disease. TSH-binding inhibitor activity of a human TSH preparation (Kabi Diagnostica) was not detectable at 100 mU/L, but detectable at 1,000 mU/L. Consistent with this, TBII activity was not detectable in hypothyroid patients with goitrous Hashimoto's disease, whose serum TSH concentrations were 11-520 mU/L. Of 57 patients with Hashimoto's disease positive TBII activity was detected in only 7 of 15 patients (46%) with primary atrophic hypothyroidism. Five of these had very high TBII activities (greater than 90% inhibition of labelled TSH binding), and no linear dose-response relationship was observed in dilution experiments. For exact determination of TBII activity in specimens with high activities, serum samples were diluted with normal pooled serum and activities were expressed in U/ml by comparison with values for standard serum, prepared from bovine TSH diluted with normal pooled serum. In this way, samples with TBII activities of 1-50 U/ml (20-90% inhibition of binding of labelled TSH) showed linear dose-response relations in dilution experiments, and the dilution curves of all samples examined were parallel to the standard curve. This standardization procedure was used in determining the half life of TBII.

Autoantibodies↗
PubMed1985

[Contribution of amino acid deficiency to primary hypothyroidism associated with protein-calorie malnutrition].

A 68-year-old male patient without any previous thyroidal disease developed three times of transient primary hypothyroidism associated with protein-calorie malnutrition (PCM). Because of his diabetes mellitus, alcoholic hepatitis, chronic pancreatitis and blind loop syndrome, his nutritional balance was easily disturbed leading to PCM. Although he recurrently developed primary hypothyroidism associated with PCM, this condition was completely restored by protein-calorie repletion. The possibility of dietary iodine deficiency was negated by the observation that his daily urinary iodine secretion was more than 4 mg/day. Plasma amino acid analysis revealed severe depletion of phenylalanine, tyrosine and other essential amino acids and raised the possibility that this hypothyroidism was caused by amino acid deficiency. In order to clarify the mechanisms of this primary hypothyroidism, we have investigated the change of thyroid functions during protein-calorie repletion by total parenteral nutrition (TPN). We then removed iodine from the nutrients for TPN to ascertain that iodine deficiency was not the cause of the primary hypothyroidism in the present case. In spite of the removal of iodine, serum T4 and T3 suddenly increased from 1.1 micrograms/dl and less than 25 ng/dl to 3.5 micrograms/dl and 59 ng/dl, respectively, in a few days after the beginning of TPN. They continued to increase thereafter and reached 6.3 micrograms/dl and 115 ng/dl in 6 weeks. Serum free T4 also showed a sudden increase from 0.56 ng/dl to 1.7 ng/dl after TPN and remained above 1.3 ng/dl thereafter. Serum reverse T3 showed a rapid increase after TPN, but, 4 weeks later, returned to the previous level before TPN. Serum TSH decreased from 120 microU/ml to 17 microU/ml in a few days after TPN and reached a level within normal range in 4 weeks. Serum TBG gradually increased from 10.7 micrograms/ml to 29.2 micrograms/ml in 6 weeks. These results show that the T4 synthesis was extremely impaired by PCM in spite of the strong stimulation by TSH and that this suppression of T4 synthesis by PCM led the patient recurrently to the primary hypothyroidism. We have next investigated the possibility whether the deficiency of phenylalanine and tyrosine could cause a suppression of T4 synthesis because tyrosine is an important substrate of T4. For this purpose we removed phenylalanine and tyrosine from TPN and added iodine to prevent iodine deficiency due to prolonged iodine-depleted nutrition. Reduction of phenylalanine and tyrosine resulted in a marked decrease in serum T4, T3 and TBG in 7 weeks, but gave no change to free T4. Serum TSH remained within normal range.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1985

Familial OKT4 epitope deficiency: studies on antigen density and lymphocyte function.

The family of a case of hereditary deficiency of OKT4 epitope on helper T cells was investigated. A 30-year-old woman was found to have hardly any OKT4+ T cells (0.7%, normal 24-51%), but normal OKT3, OKT8, OKT11, OKIa1, Leu1, Leu2a, Leu3a, Leu7, and B1 positive cells. The response to mitogens (PHA, PWM, and Con A) and helper-or suppressor-T-cell functions of her peripheral lymphocytes were normal. She had normal helper-T-cell populations detected with OKT4A (39.1%) and Leu3a (39.5%) monoclonal antibodies. One of her sisters had the same defect, but other members of the family had normal lymphocyte subsets. Lymphocyte functions were also found to be normal in all family members examined. The peak position of the fluorescence intensity of OKT4+ cells was about half that of normal controls in five members of this family. Considering that these were carriers of OKT4 epitope deficiency, the OKT4 epitope abnormality was inherited as an autosomal codominant trait in this family. Similar OKT4 epitope deficiency with normal Leu3a+ and OKT4A+ cells was found in 38 of 8866 (0.43%) other subjects in Japan by the examination of routine blood samples.

Adult↗
PubMed1985

Bovine thyrotropin inhibits DNA synthesis inversely with stimulation of cyclic AMP production in cultured porcine thyroid follicles.

The effects of bovine thyrotropin (TSH) on DNA synthesis and cyclic AMP production were studied in porcine thyroid follicles using suspension culture. During the early 72 hours incubation, the time-dependent uptake of [3H]thymidine by the follicles was observed. In the presence of 10 mU/ml TSH, the uptake of [3H] thymidine was significantly depressed at 72 hours incubation. TSH inhibition of [3H] thymidine incorporation was related to its concentration and the 50% inhibition was observed by using 1.0 mU/ml TSH. Under the same conditions, cyclic AMP production was stimulated by TSH and the stimulation was observed to be related to TSH concentration. In these experiments, the incubation time was 30 min. Dibutyryl cyclic AMP, an analogue of cyclic AMP, inhibited the [3H] thymidine uptake at 72 hours incubation. From these results, it is suggested that TSH inhibits DNA synthesis, and that the inhibition may be mediated by cyclic AMP that is produced by TSH stimulation.

Animals↗
PubMed1985

Highly sensitive immunoenzymometric assay for human thyrotropin.

A sensitive assay procedure for immunoenzymometric assay of serum thyrotropin (TSH) was developed by making several modifications of the Enzymun-Test TSH kit (Boehringer, Mannheim GmbH). Serum samples were first incubated in plastic tubes precoated with monoclonal antibodies specific to the beta subunit of human TSH. After the tubes were washed, the TSH bound to the tubes was detected with peroxidase-conjugated polyclonal antibodies to TSH. The sensitivity of the assay was 0.2 milli-int. unit/L, and the intra-and interassay CVs were less than 10%. Analytical recovery was 96 to 106%. The normal basal range of TSH was 0.5 to 4.8 milli-int. units/L. The basal levels of TSH in all but one of 48 thyrotoxic patients with Graves' disease were less than 0.2 milli-int. unit/L, clearly different from those of normal subjects. Thyrotoxic patients in early normal pregnancy showed TSH concentrations of 1.7 to 2.9 milli-int. units/L by conventional double-antibody radioimmunoassay, possibly from cross reactivity with human choriogonadotropin, but undetectable TSH by this method. Measurement of basal TSH by this sensitive assay can be used as an initial screening test for thyroid dysfunction.

Adult↗
PubMed1985

Enzyme immunoassay of free thyroxin in dried blood samples on filter paper.

We describe a double-antibody enzyme immunoassay for determination of free thyroxin (FT4) in dried blood samples on filter paper, with use of a T4-beta-D-galactosidase complex. The measurable range of FT4 concentration in two 3-mm blood discs, each of which contained about 2.7 microL of blood, was 1.9 to 93 ng/L, as determined by comparison with concentrations of FT4 in known serum standards. FT4 in blood samples dried on filter paper was stable for at least four weeks when kept dry at -20 degrees C, room temperature, or 37 degrees C. The mean coefficients of variation were 7.6% (within assay) and 6.4% (between assays). Results for FT4 by this method correlated well with those for serum determined by radioimmunoassay (r = 0.98). The proposed method can be used to differentiate persons with hyper- and hypothyroidism from normal subjects and those with abnormal concentrations of thyroxin-binding globulin. The procedure seems suited for screening studies.

Adult↗
PubMed1984

HLA-A and -B antigens in Japanese patients with congenital hypothyroidism and their parents.

The frequency of HLA-A and B antigens were studied in 32 Japanese patients with congenital hypothyroidism due to thyroid dysgenesis, and in their parents. The incidence of the Aw24 antigen was significantly higher in 27 mothers of patients with ectopic thyroid (91.3%, corrected P less than 0.037) and it seemed to be slightly higher in patients (77.7%) than in controls (56.8%). The Aw24 antigen was also found in 4 patients with thyroid hypoplasia and their mothers. No difference was found in the incidences of the antigen in the fathers of patients and in controls. The haplotype frequencies were not significantly different in controls, patients and their parents. These findings suggest that the gene for susceptibility to congenital hypothyroidism due to thyroid dysgenesis is closely linked to the gene for the HLA-A locus of the patients' mothers.

Adolescent↗
PubMed1984

Relation of structural polarity to responses of cyclic 3', 5'-adenosine monophosphate accumulation and thyroid hormone release in cultured human thyroid follicles.

The relationship of structural polarity to functional activities was examined in cultured human thyroid follicles, which were isolated from the thyroid gland of patients with Graves' disease by collagenase treatment. Structural polarity was examined morphologically by electron microscopy, while the functional response to bovine TSH was examined by measuring intracellular cAMP accumulation and T3 release. In freshly isolated thyroid follicles, structural polarity was normal and TSH induced significant cAMP accumulation but no significant release of T3. After culture for 5 days the structural polarity of thyroid follicles became inverted in the absence of thyroid stimulators, but normal polarity was retained in the presence of TSH or dibutyryl cAMP [Bu)2 cAMP). The response to TSH of cAMP accumulation increased markedly after culture in either the presence or absence of TSH, suggesting that cAMP accumulation in response to TSH is not related to structural polarity. In contrast, thyroid follicles cultured without thyroid stimulators showed no significant T3 release in response to TSH, whereas those cultured with TSH or (Bu)2 cAMP showed significant T3 release in response to TSH. These data indicate that in cultured human thyroid follicles, the responses to TSH of cAMP accumulation and T3 release are not always correlated. Among many other explanations, the results were at least compatible with the idea that normal structural polarity is necessary for thyroid hormone release in response to TSH.

Bucladesine↗
PubMed1984

Enzyme immunoassay of free thyroxin in serum.

We describe a double-antibody enzyme immunoassay for free thyroxin (FT4) in serum with use of beta-D-galactosidase conjugated to thyroxin. The method is uninfluenced by thyroxin-binding globulin or albumin. Values for FT4 so determined correlated well with those determined by radioimmunoassay (r = 0.98) and equilibrium dialysis (r = 0.89). The mean variability (CV) within and between assays was 7.4% and 7.6%, respectively. The measurable range of FT4 in serum was 2.8 to 109 ng/L. The FT4 concentrations in serum as determined by this method were 8.4 to 15.5 ng/L for 26 normal adult subjects; 26 to greater than 109 ng/L for 10 patients with hyperthyroidism; less than 2.8 to 8.0 ng/L for seven patients with hypothyroidism; 7.3 to 15.8 ng/L for eight pregnant women; and 12.2 and 13.5 ng/L for two patients with low concentrations of thyroxin-binding globulin.

Adult↗