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Biomedical subjects

R C Smallridge

Publications and source records attributed to R C Smallridge.

At least 91 records · Page 5Linked to original sources
PubMed1986

Familial medullary thyroid carcinoma without associated endocrinopathies: a distinct clinical entity.

In an evaluation of 213 patients from 15 kindreds with familial medullary thyroid carcinoma (MTC), we detected 41 subjects from two kindreds (L and O) who had MTC but no extra-thyroidal manifestations (hyperparathyroidism, phaeochromocytomas or mucosal neuromas) of multiple endocrine neoplasia (MEN) type IIa or IIb. In screening 178 members of the L and O kindreds, we found no evidence that any of them had died from MTC. To assess whether the malignancy was relatively indolent in these families, 20 selected subjects from the two kindreds were compared with 33 MEN IIa subjects. Both groups had clinically occult disease which was diagnosed biochemically by documenting elevated plasma calcitonin (CT) levels following stimulation with intravenous calcium and pentagastrin. There were no differences in the peak stimulated plasma CT levels at the time of diagnosis (1055 +/- 236 pg/ml versus 1096 +/- 191 pg/ml) or the incidence of regional lymph node metastases (0/20 versus 1/33) in the two groups. The mean age at diagnosis, however, was significantly higher in patients of the L and O kindreds than in patients with MEN IIa (43.1 +/- 3.4 years versus 21.1 +/- 2.2 years; P less than 0.001) indicating that in the two kindreds the MTC either developed at a later age or grew more slowly. This study demonstrates that MTC may occur in a familial pattern distinct from its presentation as MEN IIa or MEN IIb. In this setting it appears to be the least aggressive form of MTC yet described.

Adolescent↗
PubMed1986

Angiotensin-converting enzyme: characteristics in human skin fibroblasts.

Angiotensin-converting enzyme, although most prominent in vascular endothelium, has been identified in numerous tissues. Recent studies have indicated that several hormones, including glucocorticoids and thyroid hormone, may affect the activity of this enzyme. In the present study, angiotensin-converting enzyme was examined in homogenates of cultured human skin fibroblasts. Angiotensin-converting enzyme activity was measured by a radiometric assay using [Glycine-1-14C] Hippuryl-L-histidyl-L-leucine (1.1 mmol/L) as substrate, and was expressed as nmol hippuric acid formed per minute/mg protein. Angiotensin-converting enzyme was identified in all five cell strains tested, and the activity observed was 0.97 +/- 0.18 nmol/min/mg protein (mean +/- SE). The optimum pH was between 6.9 and 7.6, and optimum temperature was 37 degrees C, with loss of activity of 55 degrees C and higher. Buffer strength was optimized at Tris 0.025 mol/L, and 1.0 mol/L NaCl. Activity increased linearly with protein concentration and with time, and the Km = 1.14 mmol/L. The most potent inhibitor of fibroblast ACE was captopril (SQ 14,225) with an IC50 = 10(-10) mol/L; other inhibitors included SQ 20,881, EDTA, and phenanthroline. Competitive substrates included angiotensin-I, substance P, and bradykinin. Four hormones, T3 (10(-9)-10(-7) mol/L), 1,25 (OH)2D3 (10(-8)-10(-7) mol/L), dexamethasone (10(-7)-10(-6) mol/L), and a synthetic androgen, R1881 (10(-8)-10(-7) mol/L) were incubated with cells for 72 hours. In all incubations, there was no significant effect on cellular ACE activity induced by any agent. Angiotensin-converting enzyme activity in serum free media was less than 1% of cell activity and was unaltered by hormone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcitriol↗
PubMed1986

Comparative absorption of inhaled and intramuscularly administered atropine.

The inhalation of atropine sulfate was investigated in a randomized, 4-period, rising-dose study. Atropine sulfate 2, 4, and 6 mg by inhalation, and atropine free base 1.67 mg (equivalent to 2.0 mg atropine sulfate) by intramuscular (IM) injection were given to 8 healthy, nonsmoking subjects. Serum atropine sulfate concentrations were monitored during an 8-h period by radioimmunoassay. Mean serum concentrations and area under the serum concentration-versus-time curves (AUC) increased as the inhaled dose increased. Peak concentrations (mean +/- SD) were 11.5 +/- 3.4, 16.4 +/- 6.2, and 18.0 +/- 3.1 ng/ml for the 2, 4, and 6 mg doses, and 11.7 +/- 2.5 ng/ml for the IM dose. The time to peak concentration for each dose was similar (mean, 0.8 to 1.9 h). The AUC ratio of the 2-mg inhaled and IM doses was 1.11 +/- 0.41. The observed bronchodilating, anticholinergic, and other pharmacologic effects were seen after all dose concentrations and were typical of atropine. This study showed that inhalation is an efficient way to administer atropine sulfate for systemic use.

Absorption↗
PubMed1986

Thyroid iodine content and serum thyroglobulin: cues to the natural history of destruction-induced thyroiditis.

Twenty-eight patients with destructive thyroiditis were followed to study the natural history of healing of thyroid gland injury. All had sequential measurements of thyroidal iodine [127I] content by fluorescent scanning (normal mean, 10.1 mg), 17 had serial serum thyroglobulin (Tg) measurements (normal, less than 21 ng/ml), and 13 had perchlorate discharge studies during the recovery phase. Seventeen patients had painful subacute thyroiditis (SAT), 9 had painless thyroiditis with thyrotoxicosis (PTT), and 2 had postpartum thyroiditis with thyrotoxicosis (PPT). Thyroidal iodine content decreased from a mean of 9.8 to a nadir of 3.8 mg in patients with SAT and from 8.5 to a nadir of 3.5 mg in patients with PTT. Mean serum Tg concentrations were highest (approximately 165 ng/ml) in both groups 1-3 months after the onset of symptoms. Abnormalities in both 127I content and Tg levels persisted for 2 or more yr in some individuals. No patient had detectable Tg antibodies by hemagglutination, but low titers were detected intermittently by sensitive RIA in 5 PTT patients. Microsomal antibodies were positive in only 1 of 16 SAT patients, but in 4 of 7 PTT patients and in both PPT patients. Three patients had positive perchlorate discharge tests (2 of 8 with SAT, 0 of 4 with PTT, and 1 of 1 with PPT). Permanent hypothyroidism occurred in 3 patients (2 with PTT; 1 with SAT and positive antibodies), but did not correlate with perchlorate results. HLA typing and serum immunoglobulin measurements were not useful for predicting the clinical course. These data indicate that several years may be necessary for complete resolution of destructive thyroiditis; many patients have evidence of thyroid injury persisting long after serum thyroid hormone and TSH levels become normal.

Adolescent↗
PubMed1986

Goitrous Hashimoto's thyroiditis. Lack of association with HLA antigens.

We studied HLA antigen frequency in 54 carefully selected patients with goitrous Hashimoto's thyroiditis. All had an appropriate clinical course, positive family history, antithyroid antibodies and/or a needle biopsy indicating chronic lymphocytic thyroiditis. We found no statistically significant association with any HLA-A, -B, -C or DR specificity.

Female↗
PubMed1985

Angiotensin-converting enzyme activity. A potential marker of tissue hypothyroidism in critical illness.

We measured serum angiotensin-converting enzyme (ACE) activity radiometrically as a possible indicator of reduced thyroid function in 57 euthyroid controls, 27 patients in a noncardiac intensive care unit (13 with medical and 14 with surgical disorders), and 29 patients having coronary artery bypass grafting. In the last group, blood was obtained preoperatively and one day and one month after surgery (group 1; n = 18) or preoperatively and six hours and one day after surgery (group 2; n = 11). Patients in group 1 had significant reductions in levels of serum thyroxine (T4), triiodothyronine (T3), and thyrotropin response to protirelin one day postoperatively. The ACE activity fell significantly. Patients in group 2 had low levels of T4, T3, thyrotropin, and ACE six hours postoperatively. All these levels remained low the next day, and free T4 and free T3 levels were also reduced; the reverse T3 level became elevated. Changes in ACE significantly paralleled changes in T3. The 27 patients without coronary artery bypass grafting also had significant reductions in serum T4, T3, and ACE levels. Dilution studies and dialysis of serum with low ACE activity failed to demonstrate an inhibitor to explain the reduced enzyme function.

Adult↗
PubMed1985

Effects of exercise and physical fitness on the pituitary-thyroid axis and on prolactin secretion in male runners.

The effects of acute exercise and thyrotropin-releasing hormone on the pituitary-thyroid axis were examined in men placed into three well-defined categories of physical fitness. There were 20 sedentary men, 22 joggers (running four to 20 miles per week) and 18 marathoners (running 30 to 100 miles per week) who participated. During treadmill exercise, the mean VO2 max differed among all groups, being 38.5, 45.0, and 60.3 mL/kg . min in the sedentary, jogger, and marathon groups, respectively. Serum was obtained before, immediately after, and one hour after exercise for measurement of thyroxine (T4), triiodothyronine (T3), reverse T3, thyrotropin (TSH), and prolactin. Basal values of all hormones did not differ among the groups. Maximal short-term treadmill exercise produced no change in serum T4, T3, reverse T3, or TSH. Prolactin rose significantly by a similar amount in all three subject groups. On a separate day, ten individuals from each group received thyrotropin releasing hormone (TRH; 500 micrograms IV). Neither the peak TSH response nor the total TSH secreted during two hours after TRH differed among groups. The mean total prolactin secretion in the joggers and marathoners was 48% and 45% greater, respectively, than in the sedentary men. Five subjects in each group also underwent a TRH test immediately postexercise. Similar to the results on the nonexercise day, the integrated TSH response to TRH was similar in all three groups, whereas the integrated PRL response to TRH was increased by 52% and 78% in the two conditioned groups. Post-TRH sera from one subject in each group were fractionated on a Sephadex G-100 column.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Atropine serum concentrations after multiple inhaled doses of atropine sulfate.

Atropine may be given by inhalation for bronchodilation. Intravenous atropine at doses of 0.32 to 1 mg yields serum levels of 2 to 6 ng/ml, with an elimination t1/2 of about 4 hours. Efficient inhalation of large single doses leads to similar concentrations in some individuals, but under clinical conditions drug delivery may be less efficient. Of concern is accumulation of the drug in the body with multiple-dose therapy. We measured serum levels of atropine after single inhaled doses and again after 48 to 72 hours of inhalation every 4 to 6 hours in 11 subjects. The drug was administered by therapists at doses and techniques commonly used in the clinical setting. Serum concentrations of atropine were negligible after the first dose in all subjects but were detectable in six of nine subjects who received the drug for more than 48 hours. Three of the subjects had levels greater than 2 ng/ml.

Absorption↗
PubMed1985

A longitudinal evaluation of thyroid function in critically ill surgical patients.

Thyroid hormone alterations (known as the "sick-euthyroid syndrome") are common following major surgery, but the time course for appearance and recovery from these alterations has not previously been longitudinally studied in a large group of surgical patients. The authors prospectively studied 59 patients undergoing major surgery (coronary artery bypass grafting, pneumonectomy, or subtotal colectomy). Compared with preoperative values, the mean serum T4, T3, free T3, and TSH concentrations decreased significantly (p less than 0.05) following surgery. Serum reverse T3 and T3 resin uptake index increased, while free T4 levels remained unchanged. These changes were seen within 6 hours of surgery and normalized by 1 week after surgery. Although the serum TSH response to TRH was normal before and after surgery in 56 of the 59 patients, the maximal TRH-induced increase in serum TSH and the integrated serum TSH response to TRH were suppressed in the early perioperative period. This postoperative TSH suppression correlated with elevated postoperative plasma dopamine concentrations (r = 0.57, p less than 0.05). Three patients with compensated primary hypothyroidism were detected in the study and represent the first documentation of serial thyroid hormone and TSH levels in hypothyroid patients undergoing major surgery. These patients had similar changes in thyroid hormone values compared with euthyroid patients. The serum TSH response to TRH was suppressed into the normal range in two of these patients on the day following surgery. The authors conclude that the sick-euthyroid syndrome occurs within a few hours of major surgery and remits with convalescence. Postoperative decreases in serum TSH may mask the diagnosis of hypothyroidism. Surgical consultants should be aware of these rapid postoperative changes so that thyroid function tests are properly interpreted in patients who have undergone major surgery.

Adult↗
PubMed1985

Evidence of extraocular muscle restriction in autoimmune thyroid disease.

Patients with Graves' disease lacking eye symptoms frequently have abnormal intraocular pressure (IOP) increases on upward gaze (greater than or equal to 3 mm Hg) indicative of apparent subclinical ophthalmopathy. Because of the close relationship between Graves' disease (GD) and Hashimoto's thyroiditis (HT), we examined 30 patients with a history of HT as well as 26 patients with a history of GD, 4 patients with a history of subacute thyroiditis, 1 patient with a history of silent thyroiditis, and 25 normal subjects for the presence of IOP abnormalities at 15 degrees and 25 degrees upgaze. While all of the patients were asymptomatic, had no exophthalmos, and were euthyroid at the time of the exam, Hertel exophthalmometer readings (mean +/- SD) for the patients with GD were significantly higher (P less than 0.005) than those for either the HT patients or normal subjects (17.1 +/- 2.4 vs. 14.5 +/- 2.3 vs. 14.4 +/- 4.2 mm, respectively). At 15 degrees upgaze, IOP abnormalities occurred in 25% and 13% of patients with GD and HT, respectively. At 25 degrees upgaze, these figures rose to 54% for the GD patients and 37% in HT patients. Only 1 of 25 normal subjects had elevated IOP changes on upgaze, as did the 1 patient with silent thyroiditis, but the patients with subacute thyroiditis did not. These data suggest the frequent presence of extraocular muscle restriction in patients with a history of HT as well as in patients with a history of GD. Maximal detection of these IOP abnormalities requires that patients be examined at 25 degrees upgaze. These data support the belief that the autoimmune bases of both GD and HT are closely linked, at least as manifested by eye muscle involvement.

Adult↗
PubMed1984

Androgen receptor abnormalities in identical twins with oligospermia. Clinical and biochemical studies.

Identical twin brothers presented with oligospermia, small testes, normal male phenotypes, elevated serum luteinizing hormone levels, and normal or elevated serum testosterone levels. Both men had low to low-normal cytosol androgen receptor binding capacity in cultured fibroblasts from pubic skin biopsy specimens. Qualitative abnormalities of cellular androgen receptors were suggested by low-normal or low nuclear androgen uptake in fibroblasts from both brothers as well as abnormal thermolability and subnormal molybdate stabilization of androgen receptors from one brother. In vivo androgen sensitivity was assessed in one twin following administration of testosterone or the non-aromatizable androgen fluoxymesterone. Fluoxymesterone suppressed serum luteinizing hormone and serum testosterone/estradiol-binding globulin, and although testosterone suppressed both serum luteinizing hormone and serum follicle-stimulating hormone, the suppression of serum luteinizing hormone by testosterone was subnormal. Both subjects showed marked exaggeration of the serum 17-hydroxyprogesterone increase after administration of human chorionic gonadotropin, despite normal serum testosterone increases, suggesting a block in testicular 17,20-desmolase, which converts 17-hydroxyprogesterone to testosterone. These studies suggest that oligospermia and block of the enzyme 17,20-desmolase may be the earliest manifestations of androgen resistance, and the finding of the syndrome of oligospermia, normal male phenotype, and androgen receptor abnormalities in identical twins indicates a genetic etiology of this disorder.

17-alpha-Hydroxyprogesterone↗
PubMed1984

Circadian growth hormone and prolactin blood concentration during a self-limited viral infection and artificial hyperthermia in man.

Growth hormone and prolactin blood concentrations were measured in five human volunteers over 28-hour periods including 24 hourly samples (0800 to 0800 hours) followed by an oral glucose tolerance test (0800 to 1100 hours) both preexposure and during the peak febrile phase of a self-limited viral infection, Sandfly fever. Several months after recovery, three of the subjects were studied for 24-hour periods while they sat in a tub of water at 41 degrees C for 2 hours from 1300 to 1500 hours. During all studies, mealtimes (0800 hours, 1130 hours, 1630 hours) and dark phase (2300 to 700 hours) were fixed. Growth-hormone concentrations were strikingly elevated throughout the 24-hour study done during the febrile period of Sandfly fever infection (P less than .01) except for the period of normal nocturnal release when they were not significantly different from the baseline study. No additional nocturnal surge was noted the already elevated growth-hormone values during the viral-induced fever. Growth-hormone values tended to decline slowly during the night but increased considerably during the glucose-tolerance test the following morning. These changes were similar to responses previously reported in patients with cases of malnutrition. A clear-cut increase in growth-hormone concentrations (P less than .001) was also seen during a brief 2-hour period of artificial hyperthermia, suggesting that elevated body temperature alone may explain part of the increase in growth-hormone values seen during the fever of infection. A nocturnal surge of growth hormone was still seen in the artificial hyperthermia study, albeit somewhat delayed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

3'-Monoiodothyronine degradation in rat liver homogenate: enzyme characteristics and documentation of deiodination by high-pressure liquid chromatography.

Characteristics of 3'-monoiodothyronine (3'-T1) degradation were examined in vitro in rat tissue homogenates. In rat liver homogenates, 3'-T1 degradation was optimal at pH 7.4, and was dependent upon time, temperature, and tissue concentration. The Michaeli's constant (Km) = 0.84 mumol/L. 3'-T1 degradation was enhanced by dithiothreitol and inhibited by propylthiouracil, sodium ipodate, ANS, and sodium azide but not by methimazole. Animals that fasted for three days had significant reductions in both hepatic T4 to T3 conversion (199 +/- 12 v 116 +/- 12 pg T3 generated/mg protein; P less than 0.001) and 3'-T1 degradation (588 +/- 31 v 148 +/- 53 pg 3'-T1 degraded/mg protein; P less than 0.001). To document that 3'-T1 degradation was occurring by deiodination, both liver and kidney homogenates were incubated with 125I-3'-T1 (approximately 3 microCi; 13.1 nmol/L). The reaction products were separated on a reverse-phase high pressure liquid chromatography (HPLC) column. In both tissues an iodide peak was generated, and no other radiolabeled peaks appeared except for 125I-3'-T1. These data suggest that 3'-T1 is metabolized by phenolic-ring monodeiodination and is enzymic in nature.

Animals↗
PubMed1984

Thyrotropin secretion in starved rats is enhanced by somatostatin antiserum.

Previous studies have demonstrated that serum TSH and GH decrease during fasting. Taking advantage of the fact that somatostatin antiserum administration is an effective, specific method of blocking endogenous somatostatin activity, we performed the present investigation to explore whether known fasting-induced increases in somatostatin might underlie the mechanism(s) of this decrement. After a 48 hour fast, two groups of male rats were anesthetized and an indwelling right atrial catheter inserted. The control rats (n = 11) were injected with normal sheep serum and the experimental rats (n = 9) were injected with a specific antiserum to cyclic somatostatin; one and one-half hours later, blood was collected in a basal state after which 200 ng TRH was injected. The basal mean (+/- SE) T3 and T4 concentrations were 23 +/- 3 ng/dl and 1.9 +/- 0.1 ug/dl, respectively, in the fasted control group and 30 +/- 2 ng/dl and 2.3 +/- 0.2 ug/dl in the fasted somatostatin antiserum injected rats. While serum T4 and T3 levels were statistically unchanged between these two groups, basal TSH increased from 537 +/- 81 ng/ml in the control rats to 2913 +/- 742 ng/ml in the somatostatin antiserum-treated rats (P less than 0.05). Basal growth hormone levels were also higher in the somatostatin antiserum-injected rats (196 +/- 19 ng/ml vs 72 +/- 7 ng/ml (P less than 0.0025). TSH peak values following TRH injection were not different in the two study groups. In summary, the present study indicates that: (1) somatostatin antiserum increases both basal GH and TSH values in fasting rats; and (2) somatostatin and TRH may act through different pathways to modulate TSH secretion. By implication, therefore, it is suggested that enhanced somatostatin-like activity may represent one mechanism mediating the fasting-induced decrement observed in serum TSH and GH.

Animals↗
PubMed1984

Low serum thyroxine and high serum triiodothyronine in nephrotic rats: etiology and implications for bioavailability of protein-bound hormone.

Traditionally, it has been thought that the bioavailable fraction of circulating serum hormones, i.e. that which is available for cellular uptake and is physiologically active, is limited to the free (nonprotein bound) hormone. However, recent evidence, based on acute organ uptake of labeled hormone, suggests that the amount of hormone which is bioavailable in vivo may exceed that which is calculated to be free in vitro. To explore the bioavailability of circulating protein-bound thyroid hormones under steady state conditions in vivo, we altered serum thyroid hormone-binding proteins in rats by inducing nephrotic syndrome with puromycin aminonucleoside. Nephrotic rats (serum albumin, 1.1 g/dl) were found to have a marked reduction in serum T4 [2.1 +/- 0.2 (SEM) vs. 6.5 +/- 0.3 microgram/dl; P less than 0.01] and an elevation of serum T3 [141 +/- 8 vs. 51 +/- 2 ng/dl; P less than 0.01]. Estimated T4 production rate was normal in nephrotic rats, and the 3- to 4-fold increase in T4 MCR appeared to account for the marked reduction in serum T4. By contrast, increased serum T3 levels in nephrotic rats reflected both a reduction (55%) in T3 MCR and an increased rate of peripheral conversion of T4 to T3. A circulating inhibitor of T4 binding to serum proteins appeared to be present in nephrotic rats. The changes in the various serum components of thyroid hormone [T4-binding prealbumin (TBPA)-bound, albumin-bound, free] produced by nephrotic syndrome were compared with the corresponding changes in indices of thyroid hormone bioavailability (MCR, urinary excretion, hepatic content, TSH suppression, single pass extraction by liver). These comparisons suggested that nephrotic syndrome results in increased bioavailability of circulating T4 and decreased bioavailability of circulating T3. The bioavailable fraction of circulating T3 in vivo seemed to include both free T3 and that which is albumin bound in vitro. The bioavailable fraction of circulating T4 resembled free T4 more than non-TBPA-bound T4 (= albumin bound + free), although a nephrosis-induced increase in bioavailability of TBPA-bound T4 was also possible. We conclude that nephrotic rats have low serum T4, which is related to accelerated T4 clearance, and high serum T3, which is related both to decreased T3 clearance and increased peripheral conversion of T4 to T3. Under steady state conditions in vivo, bioavailable circulating T3 appears to include both free T3 and the T3 that is bound to albumin in vitro.

Animals↗
PubMed1983

Serum angiotensin-converting enzyme. Alterations in hyperthyroidism, hypothyroidism, and subacute thyroiditis.

Angiotensin-converting enzyme (ACE) activity was measured in the serum samples of 247 patients with varying thyroid states. In 60 hyperthyroid patients, the mean (+/- SD) ACE level of 29.5 +/- 9.7 units/mL was higher than in all other groups. The serum ACE level was 17.0 +/- 5.1 units/mL in 129 euthyroid subjects and differed from the level of 13.9 +/- 5.1 units/mL observed in 34 hypothyroid patients. Twenty-four patients receiving exogenous thyroid hormone had elevated serum thyroxine values. Their mean serum triiodothyronine level was in the normal range, and the mean ACE level did not differ from the euthyroid mean. The mean serum ACE level fell from 30.8 to 17.4 units/mL in 35 hyperthyroid patients studied before and after therapy. In 12 hypothyroid subjects, the mean serum ACE level rose from 11.6 to 15.8 units/mL after thyroid hormone replacement. In eight of ten patients with transient hyperthyroidism (subacute thyroiditis or painless thyrotoxic thyroiditis), their highest ACE levels were observed in the hyperthyroid or transition phase and fell progressively with the lowest values being recorded during the hypothyroid or early recovery phases. Thus, ACE activity may respond to thyroid hormone, and interpretation of serum ACE levels may require knowledge of the patient's thyroid status. Serum ACE may be useful as a probe for exploring peripheral thyroid hormone action.

Adolescent↗
PubMed1983

Partial characterization and clinical correlation of circulating human immunoglobulins directed against thyrotrophin binding sites in guinea pig fat cell membranes. Development of a direct enzyme immunoassay.

To obviate several problems inherent in indirect thyroid-stimulating hormone (TSH) receptor antibody assays, we developed an enzyme-linked immunosorbent assay (ELISA) that measures antibodies binding to guinea pig fat cell membrane, which contain high concentrations of TSH receptors. Solubilized guinea pig fat cell membranes were adsorbed to plastic microtiter plates and served as the solid-phase antigen. Test sera and affinity-purified alkaline phosphatase-conjugated anti-human IgG were co-incubated with membranes, after which p-nitrophenyl phosphate was added. Results were read when a positive control reached a standard color change (OD405nm). Specificity of this assay was demonstrated by the inability of albumin, insulin, TSH subunits, propranolol, or dexamethasone to block binding 30. normal subjects had a mean OD value of 0.080 +/- 0.050 (SD). 23 of 25 untreated Graves' patients had OD values at least 2 SD above the normal mean (Grave's mean +/- SD; 0.46 +/- 0.33, P less than 0.001) and in each case 10(-6) M TSH inhibited the binding by at least 60%, suggesting that the immunoglobulins were directed at the TSH receptor. Seven of 25 serum samples from patients with Hashimoto's disease, seven of 23 serum samples from patients with transient hyperthyroidism (subacute thyroiditis or painless thyrotoxic thyroiditis), and two of 10 samples from patients with thyroid carcinoma had significant elevations in the titers of membrane-directed immunoglobulins. Graves' patients who were treated with ablative therapy at least 6 mo earlier and who were euthyroid when restudied continued to have abnormally elevated membrane-directed immunoglobulins in six of eight samples studied. Further studies involved the substitution of affinity-purified alkaline phosphatase anti-IgM antisera for the anti-IgG antisera routinely used. Seven of 12 serum samples from patients with Graves' disease had significant elevations in binding which in every instance was inhibited by greater than 60% by 10(-6) M TSH. In sum, the present results indicate that (a) we have developed a sensitive, specific, reproducible, convenient ELISA for the measurement both of the total amount of circulating membrane-directed antibodies and of TSH-displaceable membrane-directed immunoglobulins. (b) This ELISA detected significant elevations in TSH-displaceable guinea pig membrane binding in 23 of 25 untreated Graves' patients as well as in approximately 30% of patients with Hashimoto's thyroiditis and subacute thyroiditis. (c) Elevated membrane directed antibodies may continue to be present many months or years after restoration of the euthyroid state. (d) Circulating membrane binding IgM immunoglobulins have been detected in patients with Graves' disease. Further studies using this ELISA should prove useful in a variety of investigative and clinical studies.

Adipose Tissue↗