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Biomedical subjects

T P Foley

Publications and source records attributed to T P Foley.

At least 19 recordsLinked to original sources

Thyrotoxicosis in childhood.

Evidence supports the presence of a genetic predisposition to an abnormality in immune surveillance, with environmental factors precipitating the development of Graves' disease.

Child

The relationship between autoimmune thyroid disease and iodine intake: a review.

There is evidence to suggest that elevated levels of iodide in the diet are associated with autoimmune thyroid disease (ATD) in susceptible individuals, and that autoimmune thyroiditis (Hashimoto's disease) is less common in susceptible individuals who live in regions with dietary iodine deficiency. There are epidemiologic studies in endemic goiter areas that report an increase in ATD, particularly thyroiditis, after the therapeutic administration of iodized salt, bread and oil. Lymphocytic infiltration of the thyroid is rarely found in patients from severe endemic goiter regions, yet there is a reversal of this observation after dietary iodine supplementation. Thyroid antibodies, both thyroglobulin (TgAb) and peroxidase (TpAb) or microsomal, were not detected in serum from patients with endemic goiter, but became positive in 43% of subjects three and six months after therapy with iodized oil, and there developed transient hyperthyroidism. Similarly, the addition of iodine to the diet or the administration of iodine-containing medications increases the frequency of ATD and the severity of existing autoimmune thyroiditis. Furthermore, autoimmune thyroiditis has been induced by the administration of excess iodide to strains of chickens and rats that are genetically predetermined to develop the disease. We are beginning to understand the pathogenesis of ATD. In hyperthyroidism the evidence clearly supports the hypothesis that TSH receptor antibodies (TRAb) stimulate the TSH receptor to induce excessive and sustained secretion of thyroid hormones. Cellmediated immune mechanisms, such as antibody dependent cellmediated cytotoxicity (ADCC), initiate the lymphocytic infiltration and thyrocytotoxicity in autoimmune thyroiditis. The mechanisms that initiate the development of the abnormal immune response and the relationship of ATD with excess iodide are poorly understood. There is evidence that an increase in the iodination of thyroglobulin (Tg) enhances its immunogenicity. The results of clinical and experimental studies support the requirement of a genetic predisposition to the development of ATD that may be precipitated by exposure to certain environmental factors. Another mechanism supported by experimental data is the direct toxic effect of excess iodide on iodide-deficient thyroid glands. High concentrations of iodide after oxidation to iodine causes epithelial necrosis and inflammation associated with lipofuscin accumulation suggestive of toxicity mediated by lipid peroxidation from excessive amounts of free radicals. The epithelial damage would initiate inflammatory and immune responses. Although these mechanisms would relate to the onset of autoimmune thyroiditis on exposure to excessive amounts of iodide, the relationship of iodide intake and autoimmune hyperthyroidism is less clear.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals

Effects of perinatal undernutrition on elimination of immature myosin isoforms in the rat diaphragm.

The effect of perinatal undernutrition on the postnatal elimination of immature myosin isoforms in rat diaphragm muscle was examined using electrophoretic and immunocytochemical techniques. Electrophoresis of native myosin showed that neonatal bands were present in diaphragm muscles of both control and undernourished rats on day 4. By day 21, the neonatal bands were diminished in the control diaphragm compared with the diaphragm of the undernourished rats. Neonatal bands persisted on postnatal day 30 in the diaphragm of the undernourished rats but not in the diaphragm of control rats. No significant difference in the time course of elimination of embryonic myosin light chain (LCemb) was observed between the diaphragm muscles of control and undernourished rats with two-dimensional gel electrophoresis. Immunocytochemical analysis demonstrated embryonic myosin heavy chain (MHCemb) in all myofibers of the diaphragm muscle of both groups at day 4, but this isoform was not detected in either group by day 14. Reactivity with anti-neonatal myosin heavy chain (MHCneo) indicated that rate of elimination of the MHCneo was delayed in the undernourished state as compared with the normal rats (P less than 0.001). Serum triiodothyronine levels were measured at 14, 21, and 30 days and were significantly lower in the undernourished rats compared with age-matched controls. These data demonstrate that the normal postnatal decrease in MHCneo, but not MHCemb or LCemb, is affected by the nutritional state of the animal. We speculate that these alterations in myosin isoform transitions are induced by hypothyroidism associated with undernutrition.

Aging

Longitudinal assessment of L-thyroxine therapy for congenital hypothyroidism.

We evaluated the longitudinal response in 43 infants with congenital primary hypothyroidism during the first year of L-thyroxine therapy. Diagnosis was confirmed by serum thyroid hormone measurements by 4 weeks of age in 38 infants and between 40 and 80 days of age in the remainder. This group of infants was divided by radionuclide thyroid imaging into 34 infants with thyroid dysgenesis and nine with dyshormonogenesis. The group with thyroid dysgenesis was subdivided into 21 infants with athyreosis and 13 with residual thyroid tissue (11 ectopic and 2 hypoplastic glands). L-Thyroxine therapy, at an average dose of 10 to 14 micrograms/kg/day, was begun immediately after diagnosis, and serum concentration of total thyroxine, free thyroxine, triiodothyronine, reverse triiodothyronine, and thyroid-stimulating hormone were determined serially. Serum concentration of total and of free thyroxine became normal within 1 week of the start of therapy in all groups. Despite a similarly mild degree of hypothyroidism at diagnosis observed in infants with dyshormonogenesis or with ectopia or hypoplasia, those with dyshormonogenesis had a more sensitive response to initial thyroid hormone replacement than did patients with thyroid dysgenesis, as judged by L-thyroxine does and thyroid-stimulating hormone suppression. We conclude that the prompt restoration of clinical and biochemical euthyroidism during early infancy with doses of L-thyroxine between 10 and 14 micrograms/kg/day is a safe and effective method of therapy for children with congenital hypothyroidism.

Congenital Hypothyroidism

Juvenile Graves disease: usefulness and limitations of thyrotropin receptor antibody determinations.

Thyrotropin receptor antibodies (TRAb) were measured in serum from 49 patients with active and inactive juvenile Graves disease, and the results were compared with values from control subjects and patients with Hashimoto disease. With a thyrotropin binding inhibition immunoglobulin (TBII) assay, TRAb were found in serum from 25 (93%) of 27 patients with untreated, active Graves disease. The TRAb values remained positive in 20 (72%) of 29 patients during the first 6 months of antithyroid therapy and in 13 (54%) of 24 patients during the second 6 months. After discontinuation of antithyroid therapy, 15 patients experienced 18 episodes of relapse of thyrotoxicosis; during relapse TRAb values were positive in all but one patient. Among 19 patients who remained clinically and biochemically euthyroid after cessation of antithyroid therapy, TRAb were not detected in 28 (78%) of 36 serum specimens. Of the eight positive values from six patients, no antiidiotypic antibodies were found, and thyroid stimulating immunoglobulins (TSI) were not detected in four specimens. The TRAb determination correctly predicted the subsequent clinical course in 26 (72%) of 36 patients. Furthermore, TRAb values and results of triiodothyronine suppression tests were in agreement in 27 of 36 patients, or 75% of the time. TSI were present in serum from only 19 (73%) of 26 patients with active disease; however, TSI were negative in all patients with inactive Graves disease. During the management of Graves disease, TRAb measurements by TBII determinations are valuable in the diagnosis of active disease, assist in the decision to discontinue antithyroid drug therapy, and are useful as the T3 suppression test to predict the clinical course of the disease. The TSI measurement is most useful to determine the activity of the disease when TRAb values are positive in a euthyroid patient.

Adolescent

Clinical studies with recombinant-DNA-derived methionyl human growth hormone in growth hormone deficient children.

Thirty-six children with growth hormone deficiency were treated for up to 48 months with methionyl human growth hormone (hGH) synthesised by DNA recombinant methods. The growth rate for these children increased from 3.2 +/- 1.1 cm/yr to 10.5 +/- 2.2 cm/yr (mean +/- SD). This was similar to the effect of pituitary hGH in ten GH deficient children, 3.8 +/- 1.0 to 10.1 +/- 1.1 cm/yr. Serum somatomedin C rose from 0.26 +/- 0.23 U/ml to 0.79 +/- 0.53 U/ml after 6 months of methionyl-hGH therapy, similar to the effect of pituitary hGH. The incidence of antibody formation to methionyl-hGH was higher than that observed with pituitary hGH (Kabi) but poor growth was observed only in the one patient on methionyl-hGH who acquired high-titre high-binding-capacity antibodies to hGH. No consistent changes in levels of antibodies to Escherichia coli proteins were detected. No other allergic manifestations or systemic side-effects were demonstrable.

Adolescent

[TSH-screening program for congenital hypothyroidism. Experiences with early thyrotropin (TSH) screening].

14,919 newborn infants were screened for congenital hypothyroidism within the last 5 years using a sensitive TSH method. 10 infants with congenital hypothyroidism were discovered thus presenting a frequency of 1:4500. Four of these infants showed abnormally high TSH levels and normal thyroxine levels. The determination of TSH in cord blood--or combined with the screening program for phenylketonuria--in eluate of dried filter paper specimens is the most sensitive test for primary hypothyroidism without false negative results and a low false positive recall rate of 0.16%. After initiation of therapy with thyroxine the TSH level falls unless therapy is delayed for longer. In the latter case TSH levels may remain elevated for several months despite therapy with thyroxine. We would suggest to start therapy with triiodothyronine for up to 14 days prior to initiation of the usual thyroxine therapy.

Congenital Hypothyroidism

Screening for congenital hypothyroidism: results of screening one million North American infants.

Pilot programs for screening of newborn infants for congenital hypothyroidism began in North America in 1972. To date, the five oldest programs (Quebec, Pittsburgh, Toronto, Oregon Regional, and New England Regional) have screened 1,046,362 infants. A total of 277 infants with congenital hypothyroidism have been detected and seven have been missed, resulting in a total of 284 affected infants in the screened population and an overall incidence of one in 3,684 live births. Of the affected infants, 246 were determined to have primary hypothyroidism, an incidence of one in 4,254 births. Ten infants with secondary-tertiary hypothyroidism were detected in Quebec, Oregon, and Toronto, an incidence of one in 68,200 births. Of all the infants with primary hypothyroidism who were adequately studied, 63% were determined to have aplastic or hypoplastic glands, 14% normal or enlarged glands, and 23% ectopic thyroid tissue. The estimated minimum incidence of infants with TBG deficiency is one in 8,913 births. Only 8 of the 277 detected infants were suspected clinically to have congenital hypothyroidism prior to the time of confirmation of the diagnosis at 4 to 8 weeks of age. The cost of screening varied from $0.70 to $1.60 per infant, depending on which costs were included in the estimate. Preliminary evidence from Quebec suggests that infants treated in the program have normal developmental testing scores at 18 months of age.

Alpha-Globulins

Neonatal hypothyroidism detected by the Northwest Regional Screening Program.

The Northwest Regional Screening Program to detect congenital hypothyroidism in infants born in Oregon, Montana, Alaska, and Idaho (combined birthrate of 69,000/ yr) was added to our ongoing screening program in 1975. The program utilizes dried blood filter paper specimens collected routinely in the first few days of life in all four states and again at about 6 weeks of age in Oregon only. The screening test consist of an initial thyroxine (T4) measurement; a thyroid-stimulating hormore (TSH) determination is performed on those specimens with T4 concentrations in the lowest 3% group. Serum samples obtained by venipuncture are requested for confirmation of the diagnosis. In the first two years of the program, 25 infants with primary hypothyroidism were detected amont 110,667 infants screened, a frequency of 1:4,430. Fourteen cases of thyroxine-binding globulin deficiency were also detected, a frequency of 1:7,900. Using the T4 followed by TSH testing approach, the frequency of request for repeat specimens was 0.4% in Oregon and 0.05% in the other states. The cost per specimen was $1.96. The majority of infants lacked clinical signs or symptoms of hypothyroidism; only one infant was clinically suspected of having hypothyroidism prior to detection. The most common neonatal symptoms were constipation, lethargy, and prolonged jaundice, while the most common physical signs were hypotonia, umbilical hernia, and large fontanels. Thyroid scans showed the most common etiology to be thyroid aplasia, followed by an ectopic gland, hypoplasia, and goiter. Serum T4 concentrations were lowest in those infants with aplasia, intermediate in infants with an ectopic gland or hypoplasia, and normal in the infant with the goiter. Neonatal hypothyroidism varies in degree and has several different causes; the capacity to secrete thyroid hormone, the duration before hypothyroidism becomes clinically manifest, and possibly the eventual prognosis for intellectual function depend on the nature of the underlying cause. While the mean age at treatment was 59 days, the goal of diagnosing congenital hypothyroidism and treating affected infants by 1 month of age seems realistic.

Congenital Hypothyroidism

Variation in values for iodothyronine hormones, thyrotropin, and thyroxine-binding globulin in normal umbilical-cord serum with season and duration of storage.

We measured concentrations of thyroxine, triiodothyronine, reverse triiodothyronine, thyroxine-binding globulin, and thyrotropin in pooled samples of cord sera from normal newborns. Sera collected in winter contain significantly (p less than 0.05) higher concentrations of the first tour--14.9, 13.4, 9k9, and 7.5%, respectively--than do sera collected in summer; thyrotropin concentrations are similar in samples collected during winter and summer (p greater than 0.05). With storage, the values for the thyronines and thyrotropin decreased progressively at rates between 0.9 and 5.3% per year; those for thyroxine-binding globulin did not change significantly.

Blood Specimen Collection

1-deamino-8-D-arginine vasopressin in the treatment of central diabetes insipidus in childhood.

The effectiveness of therapy with carbamazepine and clofibrate (oral therapy), intramuscular pitressin-in-oil, and intranasal 1-deamino-8-D-arginine vasopressin has been compared in 15 children with partial or complete central diabetes insipidus. Mean daily urine volume without therapy was 5.4 l and dropped to 1.1 and 1.6 l/day while receiving pitressin and DDAVP, respectively. Oral agents decreased the daily urine volume to 2.2 l in patients with partial DI, with good symptomatic control except for some nocturia. These agents had no effect in patients with complete DI and did not alter pitressin requirements. Duration of pitressin action was 24 to 36 hours with a significant incidence of hyponatremia. The duration of DDAVP effect was 8 to 20 hours, varying in individual patients. Children with partial DI required smaller doses of DDAVP and the duration of action was longer than in those with complete DI. Control of serum electrolytes was excellent using two doses per day and nocturia was eliminated. All patients who had received pitressin had growth hormone antibodies, but continued to grow normally unless there was pre-existing growth hormone deficiency. These antibodies gradually disappeared after approximately one year of therapy with oral agents or DDAVP. DDAVP did not alter growth hormone, cortisol, or prolactin levels during sleep. DDAVP is the antidiuretic therapy of choice in children with either complete or partial DI; to date, no side effects have been demonstrated.

Adolescent

The effect of cyproheptadine and human growth hormone on adrenocortical function in children with hypopituitarism.

The cortisol response to insulin hypoglycemia was determined in ten hypopituitary children treated for four months with both growth hormone and cyproheptadine, and in six other children with hypopituitarism treated for four months with hGH alone. All patients had previously normal responses to orally administered metyrapone. There was no demonstrable difference in the F responses to insulin hypoglycemia before and four months following its discontinuation in the patients receiving hGH alone. In the ten patients on combined therapy the F response to insulin hypoglycemia was normal in five and subnormal in five patients. These ten patients were retested at least two months after cessation of CPH therapy. The F response reverted to normal in four of the five patients in whom it had been subnormal. There was no significant change in the five patients with initial normal response. No patients had signs or symptoms of glucocorticoid insufficiency. In some cases, long-term administration of CPH to children with hypopituitarism is associated with decreased F response to insulin hypoglycemia; this may represent decreased adrenocortical reserve in these patients. The previously reported enhancement of growth of hypopituitary children treated with hGH and CPH may in part be a result of decreased F production.

Adrenal Cortex

Thyroid antibodies in children and adolescents with thyroid disorders.

Thyroid antibodies were determined by three different techniques in the sera of 125 children and adolescents with thyroid disorders and in the sera of 53 short, normal children without thyroid dysfunction. The incidence of antithyroglobulin antibodies in patients with thyroiditis was highest when measured by radioimmunoassay (85%), less than when measured by hemagglutination (24%), and least by antimicrosomal antibodies (7%). No patient who had initially negative serum for RATA subsequently had positive tests during follow-up of five to 24 months, whereas eight of 31 patients with initially negative serum for ATA later developed positive tests. Treatment appeared to have a suppressive effect on RATA, but not on ATA titers, in hypothroid patients with clinical thyroiditis. The incidence of hypothyroidism in the patients with clinical thyroiditis on initial presentation was significant (37%) and suggests that identification of children and adolescents with thyroiditis is important to ensure adequate medical follow-up.

Adolescent