The interaction of signal transduction pathways in FRTL5 thyroid follicular cells: studies with stable expression of beta 2-adrenergic receptors.

Multiple signal transduction pathways interact in FRTL5 cells to promote thyroid follicular cell differentiated function and cell proliferation. In these cells, TSH is a tissue-specific mitogen that promotes DNA synthesis primarily through activation of adenylate cyclase. To further test the role of adenylate cyclase in regulating cell growth and differentiated function we have introduced into FRTL5 the human beta 2-adrenergic receptor (BAR) complementary DNA and have studied the ability of isoproterenol, alone and in combination with insulin-like growth factor I (IGF-I), to stimulate cAMP accumulation, iodide transport, [3H]thymidine incorporation into DNA, and cell growth. Wild-type FRTL5 were infected with a PLJ retroviral construct containing the BAR in either a sense (FRTL BAR) or antisense (FRTL RBAR) orientation, and cell populations were selected on the basis of resistance to the antibiotic geneticin. FRTL BAR expressed approximately 1.3 x 10(5) high affinity binding sites per cell for the beta 2-specific ligand, CGP-12177, while neither FRTL5 wild-type nor RBAR cells demonstrated any specific binding. FRTL BAR had significantly higher levels of intracellular cAMP, [3H]thymidine incorporation, and iodide uptake in the absence of added isoproterenol than FRTL RBAR or wild-type cells. In FRTL BAR, but not RBAR cells, isoproterenol stimulated a dose-dependent accumulation of cAMP, iodide uptake, [3H]thymidine incorporation, and cell growth. FRTL BAR and RBAR cells were equally responsive to TSH and to IGF-I. Isoproterenol enhanced the ability of IGF-I to stimulate [3H]thymidine incorporation in BAR but not RBAR cells. Isoproterenol partially inhibited the ability of TSH to stimulate cAMP generation and DNA synthesis. These studies demonstrate that activation of adenylate cyclase through the BAR introduced into FRTL5 cells by retroviral infection reproduces the range of biological effects in these cells stimulated by TSH and suggest that activation of adenylate cyclase is sufficient to stimulate thyroid differentiated function and cell growth. FRTL BAR cells will provide an interesting model system with which to study the heterologous regulation of both TSH and BARs through activation of a common signal transduction pathway, adenylate cyclase.

A point mutation in transthyretin increases affinity for thyroxine and produces euthyroid hyperthyroxinemia.

In a family expressing euthyroid hyperthyroxinemia, an increased association of plasma thyroxine (T4) with transthyretin (TTR) is transmitted by autosomal dominant inheritance and is secondary to a mutant TTR molecule with increased affinity for T4. Eight individuals spanning three generations exhibited the abnormality. Although five of eight individuals had elevated total T4 concentrations, all affected individuals were clinically euthyroid and all had normal free T4 levels. Purified TTR from the propositus had an affinity for 125I-T4 three times that of control TTR. Exons 2, 3, and 4 (representing greater than 97% of the coding sequence) of the TTR gene of DNA prepared from the propositus' peripheral blood leukocytes were amplified using the polymerase chain reaction (PCR) and were sequenced after subcloning. Exons 2 and 3 were indistinguishable from normal. In 50% of clones amplified from exon 4, a substitution of adenine (ACC) for guanine (GCC) in codon 109 resulted in the replacement of threonine-for-alanine, a mutation confirmed by amino acid sequencing of tryptic peptides derived from purified plasma TTR. The adenine-for-guanine substitution abolishes one of two Fnu 4H I restriction sites in exon 4. PCR amplification of exon 4 of TTR and restriction digestion with Fnu 4H I confirmed that five affected family members with increased binding of 125I-T4 to TTR are heterozygous for the threonine 109 substitution that increases the affinity of this abnormal TTR for T4.

The head circumference growth curve for Japanese children between 0-4 years of age: comparison with Caucasian children and correlation with stature.

Controversy exists regarding possible international and interracial differences in head circumferences of children. We undertook the present study in order to see if there was a difference in head circumference between Japanese and Caucasian children. The subjects consisted of a total of 42,392 Japanese children between 0 and 4 years of age surveyed from 1940 to 1980, and these data were compared with those of American and British children. We conclude that there is a significant ethnic difference in head circumference, as large as one channel of usual percentiles, between Japanese and Caucasian children. The results indicate that smaller head circumference in Japanese children primarily reflects smaller stature of the Japanese.

Somatostatin inhibits deoxyribonucleic acid synthesis induced by both thyrotropin and insulin-like growth factor-I in FRTL5 cells.

Somatostatin, a cyclic tetradecapeptide, is both a hypothalamic hormone and a paracrine peptide, with effects on many tissues. Despite the fact that somatostatin can inhibit various cellular events in a number of cell lines, somatostatin is a constituent of medium defined for optimal growth of FRTL5, a line of differentiated and nontransformed rat thyroid follicular cells. In the present study we have evaluated the role of somatostatin in the control of DNA synthesis in FRTL5 cells and have investigated the mechanisms of somatostatin interaction with pathways stimulated by TSH and insulin-like growth factor-I (IGF-I). Somatostatin inhibits TSH-stimulated DNA synthesis and cell proliferation in FRTL5 cells. Maximal effects are observed at somatostatin concentrations of 0.1-10 ng/ml, and the effects are diminished at somatostatin concentrations above 10 ng/ml. Somatostatin also inhibits (Bu)2cAMP-stimulated DNA synthesis, suggesting that the loci of somatostatin action are both proximal and distal to activation of adenylate cyclase. Somatostatin also inhibits DNA synthesis stimulated by insulin-like growth factor-I (IGF-I), a pleiotropic growth factor that works through non-cAMP-dependent pathways. The somatostatin analog octreotide is more potent than native somatostatin in inhibiting DNA synthesis stimulated by either TSH or IGF-I. Somatostatin does not alter TSH or IGF-I binding to FRTL5, demonstrating that somatostatin affects the postreceptor signal transduction pathways stimulated by these factors. We conclude that 1) the use of somatostatin in hormone-supplemented medium for FRTL5 is unnecessary and may inhibit cell growth; 2) somatostatin can inhibit the direct effects of IGF-I on peripheral tissues in addition to its ability to interfere with IGF-I synthesis by inhibiting the synthesis and release of pituitary GH; and 3) somatostatin is a useful tool for dissecting the pathways involved in mediating differentiated function and growth of FRTL5 cells.

Lack of linkage between height and weight and age at menarche during the secular shift in growth of Japanese children.

During the past century, Japanese children have shown a most dramatic secular trend toward earlier menarche and accelerated tempo of growth. In order to assess the inter-relationship between these dual secular trends, we analysed the data on height and weight measurements of Japanese children, collected by the Japanese Ministry of Education in the years from 1900 through 1986, with reference to various retrospective studies on the age of menarche among Japanese. Between 1950 and 1983, both the mean height and weight at menarche varied significantly but percentage of the mean height achieved at menarcheal age, as compared with the mature height, remained relatively stable at approximately 95%. The results indicate that the secular trend toward earlier menarche reflects largely, if not solely, the secular change in tempo of physical growth in Japanese children.

The binding characteristics and biological effects in FRTL5 cells of placental protein-12, an insulin-like growth factor-binding protein purified from human amniotic fluid.

We have studied the binding of recombinant human insulin-like growth factor I (hIGF-I), and hIGF-II, and rat IGF-II [rIGF-II (multiplication-stimulating activity)] to the human amniotic fluid IGF-binding protein placental protein-12 (PP12). PP12 displayed a 5- to 10-fold higher affinity for IGF-I compared to hIGF-II or rIGF-II. These differences in binding affinity were confirmed by both saturation binding analysis and competitive binding analysis using 125I-labeled IGF-I, hIGF-II, and rIGF-II and each of the unlabeled ligands. PP12 produced dose-dependent inhibition of IGF-I-stimulated [3H]thymidine incorporation in the rat thyroid follicular cell line FRTL5. Inhibition of IGF-I-stimulated thymidine incorporation paralleled the ability of PP12 to inhibit IGF-I binding to the surface of FRTL5. At a high concentration, PP12 also inhibited TSH-stimulated DNA synthesis but did not inhibit the binding of 125I-labeled TSH to FRTL5. Insulin did not inhibit the binding of 125I-labeled IGFs to PP12, and PP12 did not inhibit the ability of insulin to stimulate DNA synthesis. These data suggest that the ability of PP12 to inhibit TSH-stimulated DNA synthesis is through the inactivation of IGF produced endogenously by FRTL5. Low concentrations of PP12 produced a statistically significant enhancement of TSH-stimulated DNA synthesis; the mechanism by which this occurs remains unclear.

On-off phenomenon in a child with tetrahydrobiopterin deficiency due to 6-pyruvoyl tetrahydropterin synthase deficiency (BH4 deficiency).

Marked fluctuations in mobility, known as the on-off phenomenon, frequently emerge during the course of chronic treatment with levodopa in patients with Parkinson's disease. Similar fluctuations in mobility and mental status have been observed in a 10-year-old Japanese girl with tetrahydrobiopterin deficiency (BH4 deficiency) while receiving neurotransmitter and biopterin supplement. In order to define the underlying mechanisms for the phenomenon in our patient, we studied the temporal relationship between plasma levodopa levels and clinical status during oral (2.0 mg/kg per day) and continuous intravenous (2.0 mg/kg per 12 h) administration of the drug. Following each oral levodopa dose, the plasma concentration of levodopa peaked at 60-90 ng/ml within 60 min and fell to 5-15 ng/ml within 2 h. The clinical state of the patient varied acutely in parallel with the plasma levodopa concentrations. The clinical swings completely disappeared when the plasma levodopa concentrations were stabilized between 120-150 ng/ml by continuous infusion. Paradoxically, on awakening from sleep, she was invariably ambulatory despite very low plasma levodopa levels (less than 10 ng/ml). These observations indicate that the on-off phenomenon in our patient reflect the fluctuations of plasma levodopa levels as demonstrated in Parkinson's disease, but there may be substantial differences in levodopa transport across the blood-brain barrier and/or striatal dopamine-receptor interaction between Parkinson's disease and BH4 deficiency.

An immunohistochemical and ultrastructural study of an unusual case of multiple non-X histiocytoma.

An immunohistochemical and ultrastructural study of an atypical case of multiple non-X histiocytoma was done. There was involvement of the skin, lungs, and liver in a 3-month-old male infant. Microscopic examination of the cutaneous tumors revealed a dense infiltration of cells with polymorphous large nuclei and abundant eosinophilic cytoplasm in the entire dermis. Both immunohistochemical and electron microscopic studies suggested that the tumors were non-X histiocytomas. The patient's condition deteriorated with dyspnea due to rapid enlargement of tumor masses in the liver and lungs. However, at 5 months of age, the cutaneous nodules and pulmonary and hepatic lesions showed a tendency to involute. Furthermore, at 12 months of age, they were no longer detectable. The patient at 24 months of age was well with normal development. To date, no recurrence of the disease has been observed.

The physical growth of Japanese children from birth to 18 years of age. Cross-sectional percentile growth curve for height and weight.

The purpose of this paper is to set forth the standards of weight and height for the Japanese children and to discuss the mathematical methods utilized for the study. In 1980, Japanese Ministry of Health and Welfare and Ministry of Education conducted a nationwide survey of weight and height in a total of some 680,000 children from birth to 18 years of age. These data were utilized for the present study. In order to draw a mathematically designed smooth curve, we divided the subjects into 4 age groups and expressed each percentile curve of the age range in terms of a polydimensional and polynominal function using the least square method. In comparison with the presently available eye-fit cross-sectional percentile growth curve, our growth curve appears to better simulate physical growth of the contemporary Japanese children.

An unusually mild variant of Hunter's syndrome in a 14-year-old boy. Normal growth and development.

An unusually mild variant of Hunter's syndrome was described in a 14-year-old Japanese boy. He has maintained normal growth (25th percentile on the growth curve), and development (IQ 120-130) until 14 years and 4 months of age.