Biomedical subjects

R Takayanagi

Publications and source records attributed to R Takayanagi.

At least 19 recordsLinked to original sources

PubMed1995

cDNA cloning of a NGFI-B/nur77-related transcription factor from an apoptotic human T cell line.

A human T lymphoid cell line, PEER, dies by apoptosis in the presence of PMA and calcium ionophore. A new gene, TINUR, was cloned from apoptotic PEER cells. The expression of the TINUR gene is induced within 1 h after the cross-linking of the T cell Ag receptor complex. TINUR belongs to the NGFI-B/nur77 family of the steroid receptor superfamily and is an orphan receptor. TINUR binds to the same DNA sequence as NGFI-B/nur77. We also propose that the NGFI-B/nur77 family can be classified into two subtypes.

Amino Acid Sequence↗

PubMed1995

[A case of primary hypothyroidism with pituitary enlargement and abnormal secretion of growth hormone and prolactin].

A case of primary hypothyroidism accompanied by pituitary enlargement and pituitary dysfunction is documented. A 27-year-old woman was admitted to our hospital for further examination of pituitary enlargement. Endocrinological examination revealed that she had primary hypothyroidism. Her TSH level in serum was elevated to more than 300 microU/ml. She also had pituitary dysfunction such as hypersecretion of prolactin in response to TRH and paradoxical rise of GH to glucose load. Serum antibodies against the pituitary gland were negative. Magnetic resonance imaging (MRI) examination showed an enlarged pituitary gland extending to supraseller cistern, which was homogeneously enhanced after Gadolinium-DTPA treatment. Treatment with 50-100 micrograms of levothyroxine sodium normalized her thyroid function and secretion of GH and prolactin. In addition, periodic MRI examination demonstrated a gradual decrease in the size of the pituitary gland after the treatment. The above clinical course indicates that pituitary enlargement in this patient occurred as a result of primary hypothyroidism. The mechanism of the abnormal secretion of TSH, GH and prolactin secondary to primary hypothyroidism was discussed.

Adult↗

PubMed1995

Type 1 angiotensin II receptors of adrenal tumors.

The present study was designed to clarify the transcriptional regulation of the human type 1 angiotensin II receptor (AT1) gene and its pathophysiological roles in steroidogenesis by adrenal tumors. A cDNA encoding type 1 angiotensin II receptor (AT1) was isolated from a human liver cDNA library encoding a protein of 359 amino acids with seven transmembrane segments. It is very likely that human has only one type of AT1 receptor, in contrast with rodents. A genomic clone containing 217 bp of exon 1 and 2558 bp of the 5'-flanking region of human AT1 receptor gene was isolated. Its proximal promoter region contained putative TATA and GC boxes, CRE and AP1 sites. Aldosterone-producing adenoma (APA) contained significantly higher levels of mRNA for AT1 and ACTH receptors than normal tissues adjacent to APA. There were no mutations within the cytoplasmic third loops of AT1 and ACTH receptors in APAs examined. APA showed increased expression of the mRNA for P450c11 and decreased expression of the mRNA for P450c17. These results suggest that renin-independent overproduction and clinically observed ACTH-dependent production of aldosterone in APAs may results from the enhanced transcription of P450c11 and ACTH receptor genes. The mechanism of the discordantly increased expression of AT1 receptor in APA remains to be clarified.

Adenoma↗

PubMed1995

Aromatase in bone cell: association with osteoporosis in postmenopausal women.

To clarify the possible action of adrenal androgen on bone cell, the existence, characteristics and regulation of aromatase in human osteoblast-like osteosarcoma cells (HOS) and primary cultured osteoblast-like cells from normal human bones (HO) were examined in this study. Significant positive correlation between bone mineral density (BMD) and serum dehydroepiandrosterone sulfate (DHEA-S) was found in 120 postmenopausal women (51-99 years old) but no correlation was seen between BMD and serum estradiol (E2). In subset analysis, strongly positive correlation of serum DHEA-S and estrone (E1) with BMD was observed in postmenopausal women aged less than 69 years old. Administration of DHEA to ovariectomized rat significantly increased BMD and decreased relative osteoid volume in femur. These in vivo findings strongly suggested that serum adrenal androgen may be converted to estrogen in peripheral organ, especially, osteoblast and be important steroids to maintain BMD. [3H]DHEA was converted to [3H]androstenedione and [3H]androstenedione to [3H]estrone in primary cultured human osteoblast. Osteoblast-like cells showed aromatase activity, and an apparent Km and the Vmax were 4.74 +/- 0.78 nM (mean +/- SD, n = 3) and 0.83 +/- 0.79 fmol/mg protein/h for HOS, and 4.6 +/- 2.9 nM and 279 +/- 299 fmol/mg protein/h (mean +/- SD, n = 19) for HO, respectively. The aromatase activity was significantly increased by dexamethasone in a dose-dependent manner. Reverse transcription-polymerase chain reaction analysis revealed that dexamethasone increased the transcript of P450AROM gene. Osteoblast-specific promoters were also determined. Dexamethasone and 1 alpha,25-dihydroxyvitamin D3 synergistically enhanced aromatase activity and P450AROM mRNA expression. These results demonstrate that adrenal androgen, DHEA, is converted to E1 in osteoblast by P450AROM which is positively regulated by glucocorticoid and 1 alpha,25-dihydroxyvitamin D3 and important to maintain BMD in the 6 to 7th decade, after menopause.

Aged↗

PubMed1995

Up-regulation of high-affinity dehydroepiandrosterone binding activity by dehydroepiandrosterone in activated human T lymphocytes.

Although evidence indicates that dehydroepiandrosterone (DHEA) exerts direct physiological effects, its mechanism of action remains unknown. DHEA binding sites were examined using a whole-cell binding assay in a human T lymphoid cell line, PEER, revealing that a single class of high-affinity binding sites for DHEA (dissociation constant = 7.4 +/- 0.53 nmol/L, mean +/- SE, n = 4) was greatly increased when treated with DHEA, phorbol-12-myristate-13-acetate, and the Ca2+ ionophore A23187. Bound [3H]DHEA was displaced sensitively by DHEA and secondarily by dihydrotestosterone, but not effectively by other steroids, including DHEA sulfate. These results not only indicate the existence of a DHEA receptor, but also suggest that T cells become susceptible to regulation by DHEA during the process of signal-induced activation.

Binding Sites↗

PubMed1995

In vivo and in vitro evidence for the production of inhibin-like immunoreactivity in human adrenocortical adenomas and normal adrenal glands: relatively high secretion from adenomas manifesting Cushing's syndrome.

To clarify whether adrenal gland secretes inhibin in vivo in physiological or pathological conditions, we measured the levels of inhibin-like immunoreactivity (inhibin-LI) in adrenal veins (A-vein) and compared them with those in inferior vena cava (IVC) using blood samples obtained at catheterization of adrenal vein in the patients with adrenal adenoma manifesting Cushing's syndrome (Cs), aldosterone-producing adenoma, clinically non-functioning adenoma and normal adrenal gland. The tumor sides of A-veins in the patients with adenomas and also both sides of A-veins in subjects with normal adrenal glands showed significantly higher contents of inhibin-LI than their IVC. When the inhibin-LI secretion rate from adrenal gland was estimated by the difference between the levels of A-vein (tumor side) and IVC, Cs adenomas showed the highest secretion rate. Similarly, the tissue inhibin-LI content and the basal secretion rate of inhibit-LI from primary cultured cells were the highest in Cs adenomas. These findings indicated that normal adrenal glands and adrenocortical adenomas produced and secreted inhibin-LI into the general circulation in vivo and Cs adenomas have relatively high capacity for secreting inhibin-LI, and the present study provided the first in vivo evidence for adrenal inhibin-LI production in pathological conditions.

Adrenal Cortex Neoplasms↗

PubMed1995

Cushing's disease preceding sarcoidosis.

We present a 32-year-old-woman with Cushing's disease and sarcoidosis. She had been diagnosed as having Cushing's disease in 1985. She had transsphenoidal surgery followed by pituitary radiation. Subsequently her plasma cortisol level gradually decreased to normal range. In 1991, she manifested bilateral hilar lymphadenopathy on chest X-ray, erythema nodosum, subcutaneous nodules and granulomatous uveitis. From the histological findings of the skin lesions, the patient was diagnosed as having sarcoidosis. Interestingly, an inverse relationship between the disease activity of sarcoidosis and the level of serum cortisol in Cushing's disease was observed in the clinical course of this patient. Co-existence of Cushing's disease and sarcoidosis is very rare. Since the therapeutic significance of steroids in sarcoidosis has been well established, this case provides insight to the relationship between sarcoidosis and steroids.

Adrenocorticotropic Hormone↗

PubMed1994

[A case of Rathke's cleft cyst with panhypopituitarism].

A 41-year-old man was admitted to our hospital because of general fatigue, sexual debility and finger stiffness. Endocrinological examinations revealed that he had panhypopituitarism, resulting in secondary adrenal insufficiency, hypothyroidism and gonadal failure. Computed tomography (CT) of the head demonstrated a low density intrasellar mass, while brain magnetic resonance imaging (MRI) showed a high intensity mass extending from the intrasellar to suprasellar region in both T1WI and T2WI. The mass was removed by transsphenoidal surgery and histologically diagnosed as Rathke's cleft cyst. Replacement with hydrocortisone and levothyroxine sodium greatly improved the clinical symptoms. Rathke's cleft cyst causing panhypopituitarism is relatively rare. The clinical and endocrinological characteristics of Rathke's cleft cyst were discussed based on the findings in 49 Japanese cases including this case and two other cases we have experienced.

Adult↗

PubMed1994

Pancreastatin-like immunoreactivity of cerebrospinal fluid in patients with Alzheimer type dementia: evidence of aberrant processing of pancreastatin in Alzheimer type dementia.

The concentrations of pancreastatin-like immunoreactivity (PST-LI) of the cerebrospinal fluid (CSF) were measured in the patients with Alzheimer type dementia (ATD) and in age-matched normal subjects. The mean PST-LI concentration in the CSF of ATD patients was significantly lower than that of normal subjects. Gel chromatographic analysis revealed that the main PST-LI peak of ATD's CSF eluted at molecular weight (MW) 13.5 kDa. However, the age-related change of the molecular forms of PST-LI in CSF was observed in normal subjects as following; PST-LI in neonatal CSF showed one peak at MW 13.5 kDa, that of 16-64-year-old showed two peaks at MW 13.5 and 5.4 kDa, however, only one main peak was shown at MW 5.4 kDa in the CSFs of 72-85-year-old. These findings suggest that the production of PST-LI was decreased and the proteolytic cleavage, which should process big PST to PST (1-52) in normal subjects, was altered to that of neonatal type in the CNS of the patients with ATD.

Aged↗

PubMed1994

Molecular cloning and characterization of the promoter for human type-1 angiotensin II receptor gene.

We isolated a genomic clone containing 2558 bp of the 5'-flanking region and 217 bp of the first exon for the human type-1 angiotensin II receptor (AT1) gene. Primer extension and RNAase protection analyses identified a transcriptional start site (+1) at 39 and 114 bp downstream of putative TATA and GC boxes, respectively. Chimeras containing 2.6 kbp(-2558 to +79) of the 5'-flanking region and chloramphenicol acetyltransferase (CAT) gene expressed a significant CAT activity when transfected into bovine aortic smooth muscle cells (BASMC), but not the cells which had no detectable AT1 receptors, such as HeLa cells and primary cultured human skin fibroblasts. Deletion of the 5'-flanking region up to position -114 resulted in more than 20-fold increase of the reporter activity in BASMC, suggesting the presence of negatively regulating element(s) in the upstream promoter region. These results indicate that we have cloned a functional promoter for the human AT1 receptor gene.

Base Sequence↗

PubMed1994

Unique change of pancreastatin-like immunoreactivity in cerebrospinal fluid by aging.

Using a specific antiserum for the C-terminal glycine amide region of human pancreastatin (PST), pancreastatin-like immunoreactivity (PST-LI) was measured in cerebrospinal fluid (CSF) from 447 subjects (368 +/- 10.8 pmol/l, mean +/- S.E.M.) free from endocrine diseases. The CSF contents of PST-LI showed a mountain-shape type change which peaked at 40 years of age. The highest concentration was found in the group of ages 40-49 years old (412 +/- 22.9 pmol/l) and the lowest concentration was found in the group of ages 80-89 years old (293.2 +/- 45.2 pmol/l) among various age groups. Gel chromatographic examination revealed the presence of two major forms (MW 13,500 and 5,400) of PST-LI in CSF. Because of the character of this antibody, the large molecular form is possibly an N-terminally elongated PST and the other may be PST-52. This may be the first report on the unique age-related change of PST concentration in CSF.

Adolescent↗

PubMed1994

[Isolated gonadotropin deficiency and secretory discrepancy of cortisol and adrenal androgen by hemochromatosis secondary to congenital dyserythropoietic anemia].

A 37-yr-old woman was admitted to our hospital for evaluation of diabetes mellitus, liver cirrhosis and primary amenorrhea. Serological and hematological examinations revealed that she suffered from hemochromatosis secondary to congenital dyserythropoietic anemia (CDA), characterized by ineffective hematopoiesis and erythropoietic dysplasia. Iron deposition was suggested by MRI on the pancreas, liver and pituitary gland. Endocrinological examinations demonstrated that she had isolated gonadotropin deficiency and ovarian failure, resulting in hypogonadotropic hypogonadism. In addition, despite normal responses of serum cortisol and plasma aldosterone to ACTH and furosemide-standing tests, respectively, serum dehydroepiandrosterone (DHEA) responded poorly to ACTH test, suggesting selective damage of zona reticularis in adrenocortical steroidogenesis in association with hemochromatosis.

Adrenal Cortex↗

PubMed1994

Sertoli cell function declines earlier than Leydig cell function in aging Japanese men.

In order to evaluate the age-related changes in Leydig cell and Sertoli cell function, we measured serum levels of total testosterone (TT), free testosterone (FT), inhibin, LH and FSH in 116 healthy Japanese men, aged 24-92 years. Serum TT remained constant up to the age of 80 years and decreased thereafter. Serum FT declined linearly with aging and was significantly lower in men in their forties than in younger men (24-39 years old). Serum inhibin levels also declined with aging, with serum concentrations significantly lower in men older than 40 and markedly lower in men over 80 years old. LH and FSH were elevated in men over 60 and 40 years old, respectively. We also examined relationships between gonadotropins and gonadal hormones in these men divided into three age groups, young (24-39 years old), middle aged (40-59 years old) and aged (60-92 years old) men. Although there was a significant inverse correlation between LH and TT or FT for the entire population, subset analysis demonstrated that this inverse correlation was confined to men over 60 years old. In fact, in young men, TT and FT were positively correlated with LH. Overall, there was also an inverse correlation between FSH and inhibin. In subset analysis this relationship was present in both middle aged and aged men. These findings suggest that in Japanese men testicular endocrine functions decline after the fourth decade of life, and that Sertoli cell function declines earlier than Leydig cell function.

Adult↗

PubMed1994

In-vitro evidence for the regulation of 17,20-lyase activity by cytochrome b5 in adrenocortical adenomas from patients with Cushing's syndrome.

OBJECTIVE: The electron transfer system molecules, NADPH-cytochrome P450 reductase (Red) and cytochrome b5 (b5) are known to increase the relative activity of 17,20-lyase to 17 alpha-hydroxylase in vitro. Consistent with this hypothesis, we have reported recently that adrenocortical adenomas from patients with Cushing's syndrome that produced exceptionally high concentrations of androgens also contained more b5 mRNA as well as greater 17,20-lyase activity than adenomas that produced low concentrations of androgens. This finding was suggestive but inconclusive in linking b5 functionally to this difference in adenoma 17,20-lyase activity. In the present study, we have extended this finding by examining the effect of b5 on microsomal 17,20-lyase activity using an antibody against cytochrome b5. DESIGN: Biochemical quantitation of the content of b5 and Red activity in the microsomal fraction of the tumours and determination of 17,20-lyase activity in the microsomes in the presence or absence of an antibody against b5. PATIENTS: Seven patients with a clinical diagnosis of Cushing's syndrome secondary to benign adrenocortical adenoma were studied. MEASUREMENTS: The microsomal activities of 17 alpha-hydroxylase, 17,20-lyase and 3 beta-hydroxysteroid dehydrogenase were measured by in-vitro enzyme assay with thin layer chromatography. Microsomal Red activity was assayed by measuring NADPH-dependent cytochrome c reduction reaction. Cytochrome b5 concentration was determined by spectrophotometric analysis. RESULTS: An in-vitro enzyme assay of microsomal fractions from the adenoma showed that the 17,20-lyase activities of two adenomas that produced high concentrations of adrenal androgen were threefold greater than those of five other adenomas that produced low concentrations of androgens. Cytochrome b5 concentrations were greater in the two adenomas with high 17,20-lyase activity than in the other adenomas, while no significant difference in Red activity was observed among all the adenomas. The increased 17,20-lyase activity in the two adenomas was partially but significantly antagonized by an antibody against b5. CONCLUSIONS: These results suggest that differences in tissue b5 are functionally associated with differences in 17,20-lyase activity in adrenocortical adenomas in Cushing's syndrome, resulting in a dissociated secretion of cortisol and androgens in some patients.

Adenoma↗

PubMed1994

Mechanism of abnormal production of adrenal androgens in patients with adrenocortical adenomas and carcinomas.

The production of adrenal androgens can be modulated by the activities of steroidogenic enzymes and by the electron transfer system, NADPH-cytochrome P450 reductase (Red) and cytochrome b5 (b5), both of which have been shown to increase 17,20-lyase activity in vitro. To clarify the mechanism of diminished secretion of adrenal androgens in patients with adrenocortical adenoma and Cushing's syndrome and of excess secretion in patients with adrenocortical carcinoma, we investigated the enzymatic activities of cytochrome P45017 alpha, 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), and Red as well as the content of b5 in five adenomas, three carcinomas, and two normal adrenal glands. An in vitro enzyme assay using a microsomal fraction of the tissues indicated that all the tumors had almost the same degree of 17 alpha-hydroxylase activities as the normal adrenals. However, the relative activity ratio of 17,20-lyase to 17 alpha-hydroxylase of the three adenomas was markedly diminished, and 3 beta-HSD activity was apparently lower in the three carcinomas. The messenger RNA concentrations of P45017 alpha were similar in all tumors, whereas those of 3 beta-HSD were markedly lower in the carcinomas than in other tissues. Both the content of b5 and the activity of Red were significantly lower in the adenomas. These results suggest that low concentrations of adrenal androgens in patients with adrenocortical adenomas are mainly due to low 17,20-lyase activity, which may be explained in part by a lower content of b5 and Red. In addition, high concentrations of adrenal androgens in patients with adrenocortical carcinoma are mainly due to the diminished activity of 3 beta-HSD.

3-Hydroxysteroid Dehydrogenases↗

PubMed1994

No mutation in cytochrome P450 side chain cleavage in a patient with congenital lipoid adrenal hyperplasia.

Molecular basis of lipoid adrenal hyperplasia (lipoid CAH) in a Japanese patient was investigated. A 46XY Japanese female patient was clinically diagnosed as having lipoid CAH based on her clinical history of adrenal crisis at birth and the low basal concentrations of cortisol, aldosterone, adrenal androgens and testosterone in serum. In vitro studies of testicular mitochondrial enzymes confirmed a specific impairment of cholesterol side chain cleavage (SCC) activity. However, in spite of the virtual reduction of SCC activity, the amounts of immunodetectable P450scc, adrenodoxin reductase, and adrenodoxin in testicular mitochondria were almost same as those of normal testis. Furthermore, the size of each protein was similar to that of normal testis. Enzymatic amplification of the complementary DNA encoding P450scc from the patient's testis RNA and its nucleotide analysis by direct sequencing revealed no mutation. These results indicate that defective P450scc is not the lesion in this patient, confirming a previous report showing no P450scc mutations in patients with lipoid CAH. The exact lesion causing lipoid CAH in this patient is currently unknown.

Adolescent↗

PubMed1994

Catechol estrogens are more potent antioxidants than estrogens for the Cu(2+)-catalyzed oxidation of low or high density lipoprotein: antioxidative effects of steroids on lipoproteins.

In order to clarify the mechanism of antiatherogenic action of several steroids such as estrogens, dehydroepiandrosterone (DHEA) and dexamethasone, we investigated the effects of various steroids on the copper (Cu2+)-catalyzed oxidation of low density lipoprotein (LDL) or high density lipoprotein (HDL) in 0.15 M NaCl by measuring thiobarbituric acid-reactive substances (TBARS). At a concentration of 10(-5) M, estrogens strongly protected against LDL oxidation by 0.5 microM Cu2+ in the following order of inhibition: estradiol (E2) (75%), estrone (E1) (35%) and estriol (E3) (30%). However, the corresponding metabolites of these estrogens, the catechol estrogens, had an even more protective effect on LDL oxidation by 0.5 microM Cu2+ in the following order of inhibition: 2-hydroxyestradiol (2-OHE2) (98%), 2-OHE1 (97%) and 2-OHE3 (96%). E2 and 2-OHE2 from 10(-7) M to 10(-5) M inhibited LDL oxidation in a dose-dependent manner, with a more marked effect for oxidation by 0.1 microM Cu2+ than by 0.5 microM Cu2+. 10(-5) M dexamethasone produced a slight (10%) but significant inhibition of LDL oxidation by 0.5 microM Cu2+. In addition, the estrogens and catechol estrogens were also effective in protecting against HDL oxidation by 0.5 microM Cu2+. Other steroids including DHEA and DHEA-sulfate had no antioxidative effects on either LDL or HDL in this system. These results indicate that estrogens and their metabolites, the catechol estrogens, exert antioxidative effects on both LDL and HDL. The catechol estrogens may be more important antioxidants than estrogens for both LDL and HDL.(ABSTRACT TRUNCATED AT 250 WORDS)

Antioxidants↗

PubMed1994

Single amino acid substitution (840Arg-->His) in the hormone-binding domain of the androgen receptor leads to incomplete androgen insensitivity syndrome associated with a thermolabile androgen receptor.

We have characterized the androgen receptor in a Japanese girl and her maternal cousin in a family with incomplete androgen insensitivity syndrome, and have investigated the molecular basis. Whole-cell androgen binding assay in cultured genital skin fibroblasts from both patients showed a normal maximum binding capacity and a normal apparent dissociation constant. However, androgen binding in fibroblasts from both patients decreased to 30% when the assay temperature was raised from 30 degrees C to 41 degrees C, indicating the presence of the thermolability of ligand binding to the androgen receptor. Sequence analysis of the coding exons of the androgen receptor gene from the patients revealed a single nucleotide substitution at position 2881 in exon G, resulting in the conversion of arginine (CGT) to histidine (CAT) at amino acid position 840 in the hormone-binding domain of the androgen receptor. The family study showed that the mothers and the maternal grandmother of the patients are heterozygous carriers for this mutation, whereas the father does not carry it, supporting the view that androgen insensitivity syndrome is an X chromosome-linked disorder. The single amino acid substitution may explain the qualitative abnormality of the androgen receptor displaying thermolability, which is thought to be the pathogenesis of incomplete androgen insensitivity syndrome in the patients.

Androgen-Insensitivity Syndrome↗