Echographic characterization of extraocular muscles in pediatric patients with thyroid dysfunction.

PURPOSE: To characterize the size of extraocular muscles (EOMs) in a pediatric population with thyroid dysfunction using orbital echography. METHODS: Patients under age 18 with thyroid dysfunction who presented to an academic ophthalmology department from 2009 to 2020 and received orbital echography were included in this IRB-approved retrospective study. Data collected included age, clinical activity score (CAS), thyroid stimulating immunoglobulin (TSI), and extraocular recti muscle thickness on echography. Patients were organized into three age cohorts, after which statistical analysis compared recti measurements to previously reported normal ranges. RESULTS: Twenty patients with thyroid dysfunction were included. When comparing average recti muscle thicknesses of study patients to those of previously published normal children in similar age ranges, the levator-superior rectus complex was significantly increased in all age groups of children with thyroid dysfunction (p-values = <.004), and the levator-superior rectus complex was most frequently enlarged compared to published normal values (78% of eyes). CAS was not correlated with EOM size in the youngest group (5-10 years old, p-values >.315) but was significantly correlated in older groups (11-17 years old, p-values <.027). TSI was not correlated with EOM size in any group (p-values >.206). CONCLUSIONS: Echographic reference ranges for EOMs in children with thyroid dysfunction were established. There are increased rates of levator-superior rectus complex enlargement in children with TED compared to adults with TED, and EOM size is correlated with CAS in children older than 10 years. Though limited, these findings may serve as an additional tool for ophthalmologists to ascertain disease activity in pediatric patients with thyroid dysfunction.

The Value of Adding Scribe Services to 2 Distinct Pediatric Subspecialties in the Era of the Electronic Medical Record.

To evaluate the impact of adding medical scribes to 2 distinct outpatient pediatric subspecialty clinics on provider burnout, visit length, and patient satisfaction. A total of 2 pediatric endocrinologists and 2 developmental-behavioral pediatrics/pediatrician (DBP) were randomly assigned based on days of the week to see patients aged 0 to 21 years in their clinics with and without in-person medical scribes from February 2019 to February 2020. Parent satisfaction rates were examined through pre- and postappointment surveys. Provider burnout rates were assessed through the Maslach Burnout Inventory-Human Services Survey. A retrospective comparative analysis of average appointment duration was undertaken considering the scribe/no scribe random allocation in the examination room. Funding for this pilot provided by the department of pediatrics budgeted funds. Over 2923 appointments during the project dates, 829 appointments were seen with a scribe. The average appointment time for a new DBP appointment was 61 minutes with scribes and 71 minutes without (P < .001). Return patient appointments in DBP averaged 31 minutes with scribes and 43 minutes without (P < .001). There was no significant difference in appointment duration for endocrinology with and without scribes. The average time for chart completion was reduced with the presence of scribes in DBP but not in endocrinology. Out of the 209 families surveyed, patient satisfaction rates with and without a scribe did not differ in that between 96% and 97% of respondents rated the appointment overall as "excellent" for each measure of provider communication with scribes present. Finally, from the Maslach Burnout Inventory-Human Services Survey, the average score across all 4 providers for Emotional Exhaustion and Depersonalization decreased during the project period, whereas Personal Accomplishment scores increased over the project period. Scribes might be more advantageous for some subspecialties that utilize prolonged narratives in clinic notes, like DBP, and an important avenue to consider in reducing provider burnout in busy ambulatory settings.

Sonographic Evaluation of Pediatric Thyroid Nodules.

A thyroid nodule detected clinically or incidentally at medical imaging is a common indication for ultrasonography (US) in the adult population. This scenario is less frequently the case in pediatric patients, and the approach to evaluation of thyroid nodules deserves modification in these patients because of the increased probability of malignancy in children, compared with adults. Evaluating a thyroid nodule with US in a systematic way requires familiarity with a number of features that can be assessed and the terms that the radiologist uses in each category. The probability of malignancy is influenced by certain features, and several models have emerged to integrate these details into an overall risk assessment to guide management and biopsy of thyroid nodules. Clinical features of thyroid cancer differ between pediatric and adult patients, and risk factors and certain genetic syndromes portend earlier manifestation of thyroid malignancy. This article provides a review of (a) US features of thyroid nodules with an emphasis on the predictive capacity for malignancy, focused on the pediatric age group when the data exist, (b) clinical information, including risk factors and genetic syndromes pertinent to the pediatric population, and (c) the state of the current literature and controversies in diagnosing and managing pediatric thyroid cancer. ©RSNA, 2017.

Pediatric differentiated thyroid carcinoma: trends in practice and outcomes over 40 years at a single tertiary care institution.

BACKGROUND: This study aims to analyze changes in characteristics, practice and outcomes of pediatric differentiated thyroid cancer (DTC) at our tertiary care institution. METHODS: Patients <21 years of age diagnosed between 1973 and 2013 were identified. Clinicopathological data, treatment and outcomes were obtained by a retrospective review. RESULTS: Thirteen males and 68 females were divided into Group A (n=35, diagnosed before July 1993) and Group B (n=46, diagnosed after July 1993). Group B was more likely to undergo neck ultrasound (US) (70% vs. 23%, p<0.0001) and fine-needle aspiration (FNA) biopsy (80% vs. 26%, p<0.0001). Patients in Group B more often underwent total thyroidectomy as a definitive surgical treatment (87% vs. 69%, p=0.04). There was no difference in radioactive iodine use. Recurrence-free survival was similar. CONCLUSIONS: Increased use of US and FNA has affected initial surgical management in the latter part of the study, possibly due to extension of adult DTC guidelines. The effects of the new pediatric DTC guidelines need further study.

Iodide transport: implications for health and disease.

Disorders of the thyroid gland are among the most common conditions diagnosed and managed by pediatric endocrinologists. Thyroid hormone synthesis depends on normal iodide transport and knowledge of its regulation is fundamental to understand the etiology and management of congenital and acquired thyroid conditions such as hypothyroidism and hyperthyroidism. The ability of the thyroid to concentrate iodine is also widely used as a tool for the diagnosis of thyroid diseases and in the management and follow up of the most common type of endocrine cancers: papillary and follicular thyroid cancer. More recently, the regulation of iodide transport has also been the center of attention to improve the management of poorly differentiated thyroid cancer. Iodine deficiency disorders (goiter, impaired mental development) due to insufficient nutritional intake remain a universal public health problem. Thyroid function can also be influenced by medications that contain iodide or interfere with iodide metabolism such as iodinated contrast agents, povidone, lithium and amiodarone. In addition, some environmental pollutants such as perchlorate, thiocyanate and nitrates may affect iodide transport. Furthermore, nuclear accidents increase the risk of developing thyroid cancer and the therapy used to prevent exposure to these isotopes relies on the ability of the thyroid to concentrate iodine. The array of disorders involving iodide transport affect individuals during the whole life span and, if undiagnosed or improperly managed, they can have a profound impact on growth, metabolism, cognitive development and quality of life.

TSH regulates pendrin membrane abundance and enhances iodide efflux in thyroid cells.

Thyroid hormones are essential for normal development and metabolism. Their synthesis requires transport of iodide into thyroid follicles. The mechanisms involving the apical efflux of iodide into the follicular lumen are poorly elucidated. The discovery of mutations in the SLC26A4 gene in patients with Pendred syndrome (congenital deafness, goiter, and defective iodide organification) suggested a possible role for the encoded protein, pendrin, as an apical iodide transporter. We determined whether TSH regulates pendrin abundance at the plasma membrane and whether this influences iodide efflux. Results of immunoblot and immunofluorescence experiments reveal that TSH and forskolin rapidly increase pendrin abundance at the plasma membrane through the protein kinase A pathway in PCCL-3 rat thyroid cells. The increase in pendrin membrane abundance correlates with a decrease in intracellular iodide as determined by measuring intracellular (125)iodide and can be inhibited by specific blocking of pendrin. Elimination of the putative protein kinase A phosphorylation site T717A results in a diminished translocation to the membrane in response to forskolin. These results demonstrate that pendrin translocates to the membrane in response to TSH and suggest that it may have a physiological role in apical iodide transport and thyroid hormone synthesis.

Endothelin-1 impairs alveolar epithelial function via endothelial ETB receptor.

RATIONALE: Endothelin-1 (ET-1) is increased in patients with high-altitude pulmonary edema and acute respiratory distress syndrome, and these patients have decreased alveolar fluid reabsorption (AFR). OBJECTIVES: To determine whether ET-1 impairs AFR via activation of endothelial cells and nitric oxide (NO) generation. METHODS: Isolated perfused rat lung, transgenic rats deficient in ETB receptors, coincubation of lung human microvascular endothelial cells (HMVEC-L) with rat alveolar epithelial type II cells or A549 cells, ouabain-sensitive 86Rb+ uptake. MEASUREMENTS AND MAIN RESULTS: The ET-1-induced decrease in AFR was prevented by blocking the endothelin receptor ETB, but not ETA. Endothelial-epithelial cell interaction is required, as direct exposure of alveolar epithelial cells (AECs) to ET-1 did not affect Na,K-ATPase function or protein abundance at the plasma membrane, whereas coincubation of HMVEC-L and AECs with ET-1 decreased Na,K-ATPase activity and protein abundance at the plasma membrane. Exposing transgenic rats deficient in ETB receptors in the pulmonary vasculature (ET-B(-/-)) to ET-1 did not decrease AFR or Na,K-ATPase protein abundance at the plasma membrane of AECs. Exposing HMVEC-L to ET-1 led to increased NO, and the ET-1-induced down-regulation of Na,K-ATPase was prevented by the NO synthase inhibitor l-NAME, but not by a guanylate cyclase inhibitor. CONCLUSIONS: We provide the first evidence that ET-1, via an endothelial-epithelial interaction, leads to decreased AFR by a mechanism involving activation of endothelial ETB receptors and NO generation leading to alveolar epithelial Na,K-ATPase down-regulation in a cGMP-independent manner.

Pendred syndrome and iodide transport in the thyroid.

Pendred syndrome is an autosomal recessive disorder characterized by sensorineural hearing impairment, presence of goiter, and a partial defect in iodide organification, which may be associated with insufficient thyroid hormone synthesis. Goiter development and development of hypothyroidism are variable and depend on nutritional iodide intake. Pendred syndrome is caused by biallelic mutations in the SLC26A4 gene, which encodes pendrin, a transporter of chloride, bicarbonate and iodide. This review discusses the controversies surrounding the potential role of pendrin in mediating apical iodide efflux into the lumen of thyroid follicles, and discusses its functional role in the kidney and the inner ear.

Hypoxia-mediated degradation of Na,K-ATPase via mitochondrial reactive oxygen species and the ubiquitin-conjugating system.

We set out to determine whether cellular hypoxia, via mitochondrial reactive oxygen species, promotes Na,K-ATPase degradation via the ubiquitin-conjugating system. Cells exposed to 1.5% O2 had a decrease in Na,K-ATPase activity and oxygen consumption. The total cell pool of alpha1 Na,K-ATPase protein decreased on exposure to 1.5% O2 for 30 hours, whereas the plasma membrane Na,K-ATPase was 50% degraded after 2 hours of hypoxia, which was prevented by lysosome and proteasome inhibitors. When Chinese hamster ovary cells that exhibit a temperature-sensitive defect in E1 ubiquitin conjugation enzyme were incubated at 40 degrees C and 1.5% O2, the degradation of the alpha1 Na,K-ATPase was prevented. Exogenous reactive oxygen species increased the plasma membrane Na,K-ATPase degradation, whereas, in mitochondrial DNA deficient rho(0) cells and in cells transfected with small interfering RNA against Rieske iron sulfur protein, the hypoxia-mediated Na,K-ATPase degradation was prevented. The catalase/superoxide dismutase (SOD) mimetic (EUK-134) and glutathione peroxidase overexpression prevented the hypoxia-mediated Na,K-ATPase degradation and overexpression of SOD1, but not SOD2, partially inhibited the Na+ pump degradation. Accordingly, we provide evidence that during hypoxia, mitochondrial reactive oxygen species are necessary to degrade the plasma membrane Na,K-ATPase via the ubiquitin-conjugating system.

Augmentation of endogenous dopamine production increases lung liquid clearance.

We have previously reported that dopamine increased active Na+ transport in rat lungs by upregulating the alveolar epithelial Na,K-ATPase. Here we tested whether alveolar epithelial cells produce dopamine and whether increasing endogenous dopamine production by feeding rats a 4% tyrosine diet (TSD) would increase lung liquid clearance. Alveolar Type II cells express the enzyme aromatic-L-amino acid decarboxylase (AADC) and, when incubated with the dopamine precursor, 3-hydroxy-L-tyrosine (L-dopa), produce dopamine. Rats fed TSD, a precursor of L-dopa and dopamine, had increased urinary dopamine levels, which were inhibited by benserazide, an inhibitor of AADC. Rats fed TSD for 15, 24, and 48 hours had a 26, 46, and 45% increase in lung liquid clearance, respectively, as compared with controls. Also, dopaminergic D1 receptor antagonist--but not dopaminergic D2 receptor antagonist--inhibited the TSD-mediated increase in lung liquid clearance. Alveolar Type II cells isolated from the lungs of rats after they had been fed TSD for 24 hours demonstrated increased protein abundance of Na,K-ATPase alpha1 and beta1 subunits. Basolateral membranes isolated from peripheral lung tissue of tyrosine-fed rats had increased Na,K-ATPase activity and Na,K-ATPase alpha1 subunit. These data provide the first evidence that alveolar epithelial cells produce dopamine and that increasing endogenous dopamine increases lung liquid clearance.

The GTP-binding protein RhoA mediates Na,K-ATPase exocytosis in alveolar epithelial cells.

The purpose of this study was to define the role of the Rho family of small GTPases in the beta-adrenergic regulation of the Na,K-ATPase in alveolar epithelial cells (AEC). The beta-adrenergic receptor agonist isoproterenol (ISO) increased the Na,K-ATPase protein abundance at the plasma membrane and activated RhoA in a time-dependent manner. AEC pretreated with mevastatin, a specific inhibitor of prenylation, or transfected with the dominant negative RhoAN19, prevented ISO-mediated Na,K-ATPase exocytosis to the plasma membrane. The ISO-mediated activation of RhoA in AEC occurred via beta2-adrenergic receptors and involved Gs-PKA as demonstrated by incubation with the protein kinase A (PKA)-specific inhibitors H89 and PKI (peptide specific inhibitor), and Gi, as incubation with pertussis toxin or cells transfected with a minigene vector for Gi inhibited the ISO-mediated RhoA activation. However, cells transfected with minigene vectors for G12 and G13 did not prevent RhoA activation by ISO. Finally, the ISO-mediated Na,K-ATPase exocytosis was regulated by the Rho-associated kinase (ROCK), as preincubation with the specific inhibitor Y-27632 or transfection with dominant negative ROCK, prevented the increase in Na,K-ATPase at the plasma membrane. Accordingly, ISO regulates Na,K-ATPase exocytosis in AEC via the activation of beta2-adrenergic receptor, Gs, PKA, Gi, RhoA, and ROCK.

Scorpion venom decreases lung liquid clearance in rats.

It has been reported that scorpion venom causes respiratory failure and pulmonary edema. However, the effects of this toxin on lung edema clearance have not been previously studied. We examined the effects of scorpion (Tityus serrulatus) venom on the ability of the lung to clear fluid and on alveolar epithelial Na,K-ATPase. The wet-to-dry lung weight ratio was increased in anesthetized rats injected intraperitonally with scorpion venom. Lung edema clearance decreased by up to approximately 60% in rats injected with the venom. Na,K-ATPase alpha1- and beta1-subunit protein abundance and activity decreased at the basolateral membranes of alveolar epithelial type II cells incubated with scorpion venom as compared with that of control animals. There was no difference in cell injury in alveolar epithelial type II cells incubated with scorpion venom for 60 minutes compared with that of control animals. We provide here the first evidence that scorpion venom decreases lung liquid clearance, probably by downregulating Na,K-ATPase in the alveolar epithelium.

Beta-adrenergic agonists regulate Na-K-ATPase via p70S6k.

We have recently reported that the beta-adrenergic agonist isoproterenol regulates the alveolar epithelial cell Na-K-ATPase via MAPK/extracellular signal-regulated kinase and rapamycin-sensitive pathways. Here we report that isoproterenol phosphorylated the protein S6 kinase (p70S6k) in alveolar epithelial cells, which was inhibited by both rapamycin and the MEK1/2 inhibitor U-0126. In alveolar epithelial cells transfected with a p70S6k dominant negative construct, isoproterenol did not increase Na-K-ATPase total protein expression, whereas in cells transfected with a rapamycin-resistant mutant, the isoproterenol-mediated increase in Na-K-ATPase was not prevented by rapamycin. Accordingly, we provide here first evidence that isoproterenol regulates Na-K-ATPase via p70S6k in alveolar epithelial cells.

Cyclic stretch activates ERK1/2 via G proteins and EGFR in alveolar epithelial cells.

Mechanical stimuli are transduced into intracellular signals in lung alveolar epithelial cells (AEC). We studied whether mitogen-activated protein kinase (MAPK) pathways are activated during cyclic stretch of AEC. Cyclic stretch induced a rapid (within 5 min) increase in extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in AEC. The inhibition of Na(+), L-type Ca(2+) and stretch-activated ion channels with amiloride, nifedipine, and gadolinium did not prevent the stretch-induced ERK1/2 activation. The inhibition of Grb2-SOS interaction with an SH3 binding sequence peptide, Ras with a farnesyl transferase inhibitor, and Raf-1 with forskolin did not affect the stretch-induced ERK1/2 phosphorylation. Moreover, cyclic stretch did not increase Ras activity, suggesting that stretch-induced ERK1/2 activation is independent of the classical receptor tyrosine kinase-MAPK pathway. Pertussis toxin and two specific epidermal growth factor receptor (EGFR) inhibitors (AG-1478 and PD-153035) prevented the stretch-induced ERK1/2 activation. Accordingly, in primary AEC, cyclic stretch activates ERK1/2 via G proteins and EGFR, in Na(+) and Ca(2+) influxes and Grb2-SOS-, Ras-, and Raf-1-independent pathways.

Dopamine activates ERKs in alveolar epithelial cells via Ras-PKC-dependent and Grb2/Sos-independent mechanisms.

Recently it has been described that dopamine (DA), via dopaminergic type 2 receptors (D(2)R), activates the mitogen-activated protein kinase extracellular signal-regulated kinase (MAPK/ERK) proteins in alveolar epithelial cells (AEC), which results in the upregulation of Na(+)-K(+)-ATPase. In the present report, we used AEC to investigate the signaling pathway that links DA with ERK activation. Incubation of AEC with DA resulted in rapid and transient stimulation of ERK activity, which was mediated by Ras proteins and the serine/threonine kinase Raf-1. Pretreatment of AEC with Src homology 3 binding peptide, which blocks the interaction between Grb2 and Sos, did not prevent DA activation of ERK. Diacylglycerol (DAG)-dependent protein kinase C (PKC) isoenzymes, involved in the DA-mediated activation of ERK proteins as pretreatment with either bisindolylmaleimide or Ro-31-8220, prevented the phosphorylation of Elk-1, and quinpirole, a D(2)R activator, stimulates the translocation of PKCepsilon. Together, the data suggest that DA activated MAPK/ERK via Ras, Raf-1 kinase, and DAG-dependent PKC isoenzymes, but, importantly and contrary to the classical model, this pathway did not involve the Grb2-Sos complex formation.

El transporte iónico epitelial en la defensa pulmonar / The epithelia ion transport in the protection of the respiratory system

El transporte iónico juega un papel importante como primera línea de defensa pulmonar, manteniendo una capa de líquido de cantidad y características adecuadas para el buen funcionamiento del clearance mucociliar. Dentro de estos mecanismos de transporte iónico, destacan la absorción de Na+ y la secreción de Cl-, primordiales en el mantenimiento del equilibrio. Patologías genéticas, innatas o adquiridas pueden alterar este equilibrio entre absorción y secreción, resaltando la Fibrosis quística como patología genética que altera los mecanismos de transporte iónico, caracterizándose por aumento en la absorción de sodio y disminución en la secreción de Cl- a lo largo del epitelio de las vías aéreas lo que hace que estos pacientes sean susceptibles a infecciones recurrentes. El estudio del transporte de iones ha permitido la investigación de nuevas estrategias terapeúticas para estos pacientes, entre los que se destacan la amilorida en aerosol para disminuir la absorción de Na+ y ATP y UTP para mejorar la secreción de CL-