The etiology of congenital hypothyroidism (CH) may play an important role in determining disease severity, outcome, and, therefore, its treatment schedule. Radionuclide imaging (RI) is currently the most precise diagnostic technique to establish the etiology of CH. Conventional ultrasound can identify an athyrotic condition at the normal neck position and has gained acceptance for the initial evaluation of CH; however, its ability in delineating ectopic thyroid is limited. We used color Doppler ultrasonography (CDU) to assess blood flow and morphology in the detection of ectopic thyroid in 11 CH patients disclosed by neonatal screening; thyroid glands were undetectable at the normal location by gray-scale ultrasonography (GSU). The patients studied consisted of two infants for initial investigation and nine children for reevaluating the cause of CH. All of the patients underwent GSU, CDU, RI, and magnetic resonance imaging (MRI) investigation. We set RI as the defining diagnostic test for detecting ectopic thyroid and compared the imaging of CDU with those of GSU and MRI. The results of RI showed 10 ectopic thyroids and one athyreosis. In the patients with ectopic thyroid, the sensitivity of CDU, GSU, and MRI for detecting ectopic thyroid was 90, 70, and 70%, respectively. We conclude that CDU is superior to GSU and MRI for detecting ectopic thyroid and that CDU may be adopted as the diagnostic tool for the initial investigation of suspected CH.
To determine the clinical utility of thyroid ultrasonography in the diagnosis of congenital hypothyroidism (CH) before initiation of therapy, ultrasonographic images of the thyroid gland with a high-resolution transducer were obtained in 204 healthy infants aged from newborn to 12 months (Group A), and 174 infants suspected of having CH detected by neonatal mass screening (Group B). The thyroid gland was imaged by transverse scanning at the anatomic site of the thyroid gland. The maximal width of thyroid on the transverse section in the normal location was measured. By comparing with the normal thyroid gland size and location obtained from Group A, 174 infants of Group B were divided into four subgroups: 1) Normal in size (n = 117), 2) Enlarged (n = 33), 3) Small (n = 1) and 4) Invisible in the normal location (n = 23). They were compared with the final diagnoses based on the results of chemical laboratory data and scintigraphic findings. The sensitivity and the specificity for the presence or absence of the thyroid gland in the normal location were 96% (22/23) and 99% (150/151), respectively. Both subgroups of normal and enlarged sized gland included healthy infants (false positive), transient hyperthyrotropinaemia, transient hypothyroidism and CH due to dyshormonogenesis. We conclude that ultrasonography is useful for determining the presence or absence of the thyroid gland in the normal location, whereas normal and enlarged sized glands require further examination to complete the diagnosis.
Abstract.We examined clinical, endocrinological and molecular biological aspects of an estrogen-secreting adrenal carcinoma in an 18-month-old male to clarify the pathogenesis of this condition.An 18-month-old boy was referred for evaluation of progressive bilateral gynecomastia and appearance of pubic hair. The patient had elevated plasma estradiol (349 pg/ml) and testosterone (260 ng/dl) levels that completely suppressed FSH and LH levels, and was subsequently diagnosed with an adrenal tumor on the right side. After removal of a 300-g adenocarcinoma, gynecomastia regressed and essentially normal hormone levels were restored.Aromatase activity in the tumor tissue determined by the 3H-water method was 71.0-104.4 pmol/min/mg protein.High levels of aromatase protein and mRNA in the tumor tissue were also demonstrated, while neither aromatase activity nor protein was detected in normal adrenal glands. To investigate the regulation of aromatase expression in the adrenal carcinoma, we examined the usage of alternate promoters responsible for aromatase gene transcription.In the present case, the amounts of aromatase mRNA utilizing gonadal types of exon lc (I.3) and id (II) were significantly higher than those that using other exon is. This result suggested that the utilization of a gonadal-type exon 1 might be involved in the overproduction of aromatase in estrogen-secreting adrenal carcinoma.
G protein-coupled receptors (GPCRs) generally accommodate specific ligands in the orthosteric-binding pockets. Ligand binding triggers a receptor allosteric conformational change that leads to the activation of intracellular transducers, G proteins and β-arrestins. Because these signals often induce adverse effects, the selective activation mechanism for each transducer must be elucidated. Thus, many orthosteric-biased agonists have been developed, and intracellular-biased agonists have recently attracted broad interest. These agonists bind within the receptor intracellular cavity and preferentially tune the specific signalling pathway over other signalling pathways, without allosteric rearrangement of the receptor from the extracellular side1–3. However, only antagonist-bound structures are currently available1,4–6, and there is no evidence to support that biased agonist binding occurs within the intracellular cavity. This limits the comprehension of intracellular-biased agonism and potential drug development. Here we report the cryogenic electron microscopy structure of a complex of Gs and the human parathyroid hormone type 1 receptor (PTH1R) bound to a PTH1R agonist, PCO371. PCO371 binds within an intracellular pocket of PTH1R and directly interacts with Gs. The PCO371-binding mode rearranges the intracellular region towards the active conformation without extracellularly induced allosteric signal propagation. PCO371 stabilizes the significantly outward-bent conformation of transmembrane helix 6, which facilitates binding to G proteins rather than β-arrestins. Furthermore, PCO371 binds within the highly conserved intracellular pocket, activating 7 out of the 15 class B1 GPCRs. Our study identifies a new and conserved intracellular agonist-binding pocket and provides evidence of a biased signalling mechanism that targets the receptor–transducer interface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.