RESUMEN
GH-releasing peptides (GHRPs) are synthetic peptides that bind to specific receptors and thereby stimulate the secretion of pituitary GH. In vivo it is uncertain whether these peptides act directly on somatotroph cells or indirectly via release of GHRH from the hypothalamus. In this study we compared the pituitary hormone response to GHRP-2 in 11 individuals with isolated GH deficiency (GHD) due to a homozygous mutation of the GHRH receptor (GHRH-R) gene and in 8 normal unrelated controls. Basal serum GH levels were lower in the GHD group compared with controls [0.11 +/- 0.11 (range, <0.04 to 0.38) vs. 0.59 +/- 0.76 microg/L (range, 0.04-2.12 microg/L); P = 0.052]. After GHRP-2 administration there was a 4.5-fold increase in serum GH relative to baseline values in the GHD group (0.49 +/- 0.41 vs. 0.11 +/- 0.11 microg/L; P = 0.002), which was significantly less than the 79-fold increase in the control group (46.8 +/- 17.6 vs. 0.59 +/- 0.76 microg/L; P = 0.008). Basal and post-GHRP-2 serum levels of ACTH, cortisol, and PRL were similar in both groups. Basal levels of serum TSH were significantly higher in the GHD group than in the control group (3.23 +/- 2.21 vs. 1.37 +/- 0.34 microIU/mL; P = 0.003). TSH levels in both groups did not change after GHRP-2 administration. These results suggest that an intact GHRH signaling system is not an absolute requirement for GHRP-2 action on GH secretion and that GHRP-2 has a GHRH-independent effect on pituitary somatotroph cells.
Asunto(s)
Hormona de Crecimiento Humana/deficiencia , Hormona de Crecimiento Humana/metabolismo , Mutación , Oligopéptidos/farmacología , Receptores de Neuropéptido/genética , Receptores de Hormona Reguladora de Hormona Hipofisaria/genética , Hormona Adrenocorticotrópica/sangre , Hormonas/farmacología , Hidrocortisona/sangre , Hipófisis/efectos de los fármacos , Hipófisis/metabolismo , Prolactina/sangre , Tirotropina/sangreRESUMEN
OBJECTIVE: To characterize clinically and hormonally the syndrome of autosomal recessive familial growth hormone deficiency (FGHD) recently identified in Itabaianinha, Sergipe, Brazil, caused by a novel mutation (mt) that inactivates the growth hormone-releasing hormone receptor (GHRH-R) gene. DESIGN: Clinical and hormonal evaluations were performed in 21 FGHD individuals (mt/mt group) aged 8 to 63 years, 13 heterozygotes for the GHRH-R mutation (wt/mt group) and 5 homozygotes for the wild type (wt) allele (wt/wt group), identified by genotyping of peripheral blood leukocyte DNA. METHODS: Clinical and hormonal characterization included physical examination and measurement of GH, IGF-I, IGF binding protein-3 (IGFBP-3), cortisol, prolactin, LH, FSH, and free thyroxine (FT4). RESULTS: Clinical features were consistent with isolated growth hormone deficiency. Height was significantly reduced in the mt/mt group compared with the wt/mt group (mean height standard deviation score (SDS) +/- s.d.: -7.35+/-1.37 vs -1.84+/-1.44 respectively, P<0. 0001), and the wt/wt group (-1.85 +/- 0.81, P=0.0007). The height of the 13 wt/mt subjects did not differ from the 5wt/wt individuals. Serum GH, IGF-I, IGF-I SDS, IGFBP-3 and IGFBP-3 SDS were all significantly lower in the mt/mt group than in the wt/mt and wt/wt groups. Two affected children treated with GH for 1 year showed a normal growth response. Serum IGF-I and IGF-I SDS were lower in wt/mt compared with wt/wt group, but did not reach statistical significance. IGF-I and IGF-I SDS correlated inversely with age in wt/mt group. CONCLUSIONS: FGHD due to an autosomal recessive GHRH-R gene mutation leads to marked dwarfism, phenotypically and hormonally indistinguishable from other forms of isolated GH deficiency. Heterozygotes for the GHRH-R mutation appear to have a partial defect in the GH/IGF axis, with no apparent height impairment.
Asunto(s)
Hormona del Crecimiento/deficiencia , Heterocigoto , Homocigoto , Hormonas/sangre , Mutación , Receptores de Neuropéptido/genética , Receptores de Hormona Reguladora de Hormona Hipofisaria/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Brasil , Niño , Enanismo/genética , Femenino , Genes Recesivos , Humanos , Masculino , Persona de Mediana Edad , LinajeRESUMEN
Hypergonadotropic hypogonadism is characterized by decreased gonadal function due to the inability of the gonads to respond to pituitary gonadotropins. Hypergonadotropic hypogonadism in females has many causes, among which are ovarian dysgenesis and abnormalities of the ovarian receptors for the pituitary gonadotropins. We evaluated a woman who presented with amenorrhea due to hypergonadotropic hypogonadism, but who had structurally normal ovaries. She is a sister of two previously identified 46,XY male pseudohermaphrodites with Leydig cell hypoplasia. Injection of hCG did not cause any change in plasma levels of estradiol or progesterone, suggesting complete ovarian resistance to LH. Analysis of the DNA sequence of the LH receptor gene revealed that the patient is homozygous for the same single base change as her two brothers. This mutation causes substitution of an alanine residue by a proline at position 593. In vitro analysis of the mutant LH receptor in cultured human embryonic kidney 293 cells documented that the receptor is unable to stimulate adenylyl cyclase in response to hCG. Plasma levels of estradiol and progesterone were low, whereas LH and FSH levels were increased. On histological analysis of the ovary, follicles were seen at all developmental stages. Nonetheless, primary amenorrhea had been present for 5 yr, and repeated measurements of plasma estradiol and progesterone indicate that ovulation does not occur. These results document the existence of inherited LH resistance as a cause of primary amenorrhea in women. The combined clinical and molecular observations are consistent with previous experimental data suggesting that in humans, LH is necessary for ovulation but follicular maturation can occur in the presence of FSH alone.
Asunto(s)
Amenorrea/genética , Mutación , Receptores de HL/genética , Adulto , Amenorrea/etiología , Amenorrea/fisiopatología , Resistencia a Medicamentos/genética , Femenino , Humanos , Hipogonadismo/etiología , Hipogonadismo/genética , Hipogonadismo/fisiopatología , Masculino , Ovario/patología , Ovario/fisiopatología , Linaje , Hipófisis/fisiopatología , Receptores de HL/metabolismoRESUMEN
Association of pheochromocytoma and pregnancy is rare and usually related to high maternal and fetal mortality rates. Maternal effects of the tumor have been studied extensively and the clinical outcome has markedly improved during the last decade. However, the role of excess catecholamines on fetal development has been discussed very little. We report here a case of pheochromocytoma during pregnancy. In which catecholamine levels from the cord blood were low despite simultaneous elevated maternal values (1.93 and 29.46 nmol/l norepinephrine, respectively), possibly owing to the high activity of the catecholamine degradative enzymes monoamine oxidase and COMT at the placental level. We suggest that in pregnancies complicated by pheochromocytoma, fetal well-being may be related mainly to good control of maternal blood pressure instead of the amount of catecholamines in the fetal circulation, because the placenta performs a protective role through an effective process of hormone inactivation.
Asunto(s)
Neoplasias de las Glándulas Suprarrenales/sangre , Catecolaminas/sangre , Sangre Fetal/química , Recién Nacido/sangre , Feocromocitoma/sangre , Complicaciones Neoplásicas del Embarazo/sangre , Adulto , Femenino , Humanos , Intercambio Materno-Fetal/fisiología , Monoaminooxidasa/análisis , Norepinefrina/sangre , Placenta/enzimología , Placenta/fisiología , EmbarazoRESUMEN
BACKGROUND: The diagnosis of medullary thyroid carcinoma (MTC) depends on the calcitonin immunohistochemistry. Familial MTC is associated with C-cell hyperplasia (CCH), whereas sporadic MTC is not. A specific and sensitive calcitonin immunohistochemistry is necessary for the diagnosis of MTC and CCH. METHODS: An affinity-purified anti-calcitonin antiserum (APxCT) was used for immunohistochemistry of the thyroids of 15 patients with MTC. The thyroids of five patients with familial MTC were studied in detail, with each gland sectioned in 48 areas. RESULTS: Between three and ten independent MTC were found in each thyroid, and CCH was found in all five patients (24.2%, varying from 8.4-56.3% of the 48 areas from each thyroid). MTC and CCH were localized mainly in the middle third and in the central axis of the thyroid lobes. They often were found together in the same area (in a total of 21 areas for the five thyroids sectioned in 48 areas) but ten areas with MTC did not have CCH, and 37 areas with CCH did not have MTC. In ten thyroids partially studied, CCH was indicated in three patients thought to have sporadic MTC. In two thyroids, with follicular and papillary carcinoma, a higher density of C-cells was found around the tumors, but disease was not characterized as CCH. CONCLUSIONS: APxCT antiserum increased the immunohistochemical specificity and sensitivity. The distinction of the familial from the sporadic MTC requires a careful and extensive search of CCH. C-cells in high density may be found around follicular cell carcinomas, being a potential source of diagnostic error.
Asunto(s)
Calcitonina/análisis , Carcinoma/patología , Sueros Inmunes , Glándula Tiroides/patología , Neoplasias de la Tiroides/patología , Adolescente , Adulto , Calcitonina/inmunología , Carcinoma/química , Niño , Cromatografía de Afinidad , Familia , Femenino , Humanos , Hiperplasia/patología , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Glándula Tiroides/química , Neoplasias de la Tiroides/químicaRESUMEN
A female newborn whose mother was taking propylthiouracil (PTU) for Graves' disease, presented with transient thyrotoxicosis (serum triiodothyronine 1,710 ng/dl) and signs of acute hepatic injury. Jaundice and choluria were evident on her fourth day of life. Serum total bilirubin reached 14 mg/dl, with a direct fraction of 11 mg/dl. Serum alanine aminotransferase and aspartate aminotransferase showed moderate elevations (110 IU/l and 61.5 IU/l, respectively), as well as the alkaline phosphatase which increased to about twice the upper limit of normal. When incubated with PTU, the patient's cultured peripheral lymphocytes underwent transformation to more than twice the values found in 2 controls, with a stimulation index (SI) of 3.19, compared to SI of 1.45 and 1.15 for the controls, suggesting a hypersensitivity mechanism involved in the hepatic injury. Although about 20 cases of PTU induced hepatic damage were reported in the medical literature, this is, as far as we know, the first description of neonatal liver injury probably caused by placental transfer of this drug.
Asunto(s)
Enfermedad Hepática Inducida por Sustancias y Drogas/sangre , Activación de Linfocitos/efectos de los fármacos , Intercambio Materno-Fetal , Propiltiouracilo/efectos adversos , Alanina Transaminasa/sangre , Fosfatasa Alcalina/sangre , Aspartato Aminotransferasas/sangre , Bilirrubina/sangre , Células Cultivadas , Femenino , Humanos , Recién Nacido , Embarazo , Propiltiouracilo/farmacología , Tirotoxicosis/inducido químicamenteRESUMEN
The early diagnosis of medullary thyroid carcinoma was made in two among six examined siblings belonging to two sibships that were offsprings of multiple endocrine neoplasia type II parents. The calcitonin secretory reserve was determined by a combined test using Ca++ (2 mg/kg) and pentagastrin (0.5 mcg/kg), intravenously. Two abnormal tests made on different days supported the diagnosis. Basal calcitonin levels were moderately high (90-500 pg/ml; NL = 15-85 pg/ml) and peak levels were also abnormal (480-1500 pg/ml; NL less than 320 pg/ml), in both cases. Total thyroidectomy associated to prophylactic resection of lymph nodes from central neck region were performed in both. A small nodule (3-5 mm) was found in each lobe in both cases. Pathological and immunocytochemical data supported the diagnosis of medullary thyroid carcinoma. C-cell hyperplasia was present in the peritumoral zones. Pheochromocytoma and definite hyperparathyroidism were not detected in these cases. Two years after surgery, basal and stimulated serum calcitonin levels remained normal. Carcinoembryonic antigen levels were and continue to be normal, in both. These seem to be the first cases published in this country in which this early diagnosis was made.
Asunto(s)
Neoplasia Endocrina Múltiple/complicaciones , Neoplasias de la Tiroides/complicaciones , Adolescente , Adulto , Calcitonina/sangre , Antígeno Carcinoembrionario/análisis , Niño , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Neoplasia Endocrina Múltiple/genética , Radioinmunoensayo , Neoplasias de la Tiroides/diagnóstico , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/cirugíaRESUMEN
The occurrence of chronic mucocutaneous candidiasis accompanying polyglandular autoimmune syndrome type I is reported in a female aged 13. Apart the candidiasis, since the age of 3, she had convulsions beginning at 6, cataract at 9, teeth abnormalities, and basal ganglia calcifications. Laboratory data confirmed the diagnosis of hypoparathyroidism. This picture was accompanied by intestinal malabsorption, leading to a state of progressive malnutrition, with intense hypoalbuminemia and anemia. Although the pathophysiology of malabsorption, in these cases, is still not clear, the therapeutic response to pancreatin, in the present case, suggested pancreatic insufficiency, reinforced by the normal d-xylose test and the small intestinal biopsy with inexpressive result.