- Nicotinic Acetylcholine Receptor Signaling in Neuroprotection: SAK3-Induced Neuroprotection Is Mediated by Nicotinic Acetylcholine Receptors [BOOK]
- BOOKSpringer: Singapore
- Cholinergic neurotransmission plays a critical role in neuronal plasticity and cell survival in the central nervous system (CNS). Two types of acetylcholine receptors (AChRs), muscarinic AChRs (mAChR…
Cholinergic neurotransmission plays a critical role in neuronal plasticity and cell survival in the central nervous system (CNS). Two types of acetylcholine receptors (AChRs), muscarinic AChRs (mAChRs) and nicotinic AChRs (nAChRs), trigger intracellular signaling through G protein activity and ion influx, respectively. To assess mechanisms underlying neuroprotection through nAChRs, we developed SAK3, a novel modulator of nAChR activity. Recently, we found that SAK3 enhances T-type calcium channel activity, promoting ACh release in the hippocampal CA1 region of olfactory-bulbectomized mice. Here, we observed potent SAK3 neuroprotective activity in mice with 20-min bilateral common carotid artery occlusion (BCCAO) or hypothyroidism. Treatment of mice with the α7 nAChR-selective inhibitor methyllycaconitine (0.5 mg/kg/day, p.o.) antagonized SAK3-mediated neuroprotection and memory improvement in BCCAO mice. Single administration of the anti-Graves’ disease therapeutic methimazole (MMI) to female mice disrupted olfactory bulb (OB) glomerular structure, and cholinergic neurons largely disappeared in the medial septum followed by memory loss. Chronic SAK3 (0.5–1 mg/kg, p.o.) administration significantly rescued the number of cholinergic medial septum neurons in MMI-treated mice and improved cognitive deficits seen in those mice. Overall, our study suggests that, in mice, the novel nAChR modulator SAK3 can rescue neurons impaired by transient ischemia and hypothyroidism. We also address mechanisms common to SAK3-induced neuroprotection in both conditions.
- Increased remission rates after long-term methimazole therapy in patients with Graves' disease: Results of a randomized clinical trial. [Journal Article]
- TThyroid 2019 Jul 16
- BACKGROUND Studies differ regarding whether, compared to courses of conventional duration, longer-term antithyroid drug treatment increases frequency of remission in patients with Graves' hyperthyro…
BACKGROUND Studies differ regarding whether, compared to courses of conventional duration, longer-term antithyroid drug treatment increases frequency of remission in patients with Graves' hyperthyroidism. We prospectively conducted a randomized, parallel-group study comparing relapse rates in patients receiving longer-term vs. conventional-length methimazole courses. We also sought variables associated with relapse following the latter. METHODS We enrolled 302 consecutive patients with untreated first episodes of Graves' hyperthyroidism. After 18-24 months of methimazole, 258 patients (85.4%) were randomized to additional 36-102-month courses ("long-term group": n=130; scheduled total time on methimazole: 60-120 months) or discontinuation of methimazole ("conventional group": n=128). Patients were followed 48 months post-methimazole cessation. We performed Cox proportional hazards modeling to identify factors associated with relapse after conventional courses. FINDINGS Methimazole was given for 95±22 months in long-term patients and 19±3 months in the conventional group. Fourteen patients experienced cutaneous reactions and 2, liver enzyme elevations during the first 18 months of treatment; no further methimazole-related reactions were observed despite therapy for up to another 118 months. Hyperthyroidism recurred within 48 months post-methimazole withdrawal in 15% (18/119) of long-term patients vs. 53% (65/123) of conventional-group patients. In the conventional group, older age, higher triiodothyronine or thyrotropin receptor antibody concentrations, lower thyrotropin concentration, or possession of the rs1879877 CD28 polymorphism or the DQB1-05 HLA polymorphism were independently associated with relapse. INTERPRETATIONS Administration of low-dose methimazole for a total of 60-120 months safely and effectively treats Graves' hyperthyroidism, with much higher remission rates than attained using conventional 18-24-month courses. (Funded by the regular budget of the Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran; registered under identifier 5143 at the Iranian Registry of Clinical Trials, www.irct.ir/trial/5143).
- The Th1 chemokine MIG in Graves' Disease: a narrative review of the literature. [Journal Article]
- CTClin Ter 2019 Jul-Aug; 170(4):e285-e290
- Type-1 helper (Th1) dependent chemokines, such as monokine induced by interferon (IFN)-γ (MIG) seem to contribute to the Graves' disease (GD) pathogenesis. The thyrocytes secrete the chemokine (C-X-C…
Type-1 helper (Th1) dependent chemokines, such as monokine induced by interferon (IFN)-γ (MIG) seem to contribute to the Graves' disease (GD) pathogenesis. The thyrocytes secrete the chemokine (C-X-C motif) ligand (CXCL)10 under the IFN-γ influence. Therefore, high levels of MIG in peripheral liquids indicate a Th1 orientated immune response and are associated with the active phase of GD in hyperthyroid patients (newly diagnosed and relapsing). Methimazole (MMI), used for the hyperthyroidism treatment, causes a reduction of the MIG secretion by isolated thyrocytes, a decrease of serum MIG levels and leads to a shift from a Th1 to Th2 response in patients with GD in the active phase. The Th1 lymphocytes recruited in the tissues enhance the IFN-γ and tumor necrosis factor (TNF)-α production, that in turn stimulate MIG secretion from these cells; this mechanism originates an amplification feedback loop, causing a perpetuation of the autoimmune process. It has been seen that peroxisome proliferator-activated receptors (PPAR)-γ and PPAR-α activators can modulate the IFN-γ induced MIG secretion in vitro, in GD thyrocytes. More studies are needed to examine the interactions between cytokines and chemokines in the GD pathogenesis and to evaluate the role of MIG as a new therapeutic target.
- Mouse Model of Thyroid Cancer Progression and Dedifferentiation Driven by STRN-ALK Expression and Loss of p53: Evidence for the Existence of Two Types of Poorly Differentiated Carcinoma. [Journal Article]
- TThyroid 2019 Jul 12
- CONCLUSIONS: In this study, we generated a new mouse model of multi-step thyroid cancer dedifferentiation with evidence of progression from PTC to PDTC and ATC. Further, PDTC in these mice showed two distinct histologic appearances correlated with levels of expression of thyroid differentiation and iodine metabolism genes, suggesting a possibility of existence of two PDTC types with different functional characteristics and potential implication for therapeutic approaches to these tumors.
- Autoimmune Hepatitis Refractory to Treatment Due to Underlying Grave's Disease. [Case Reports]
- CCureus 2019 May 04; 11(5):e4598
- A 24-year-old Hispanic woman presented to our facility with a two-week history of abdominal pain, nausea, vomiting, diarrhea, jaundice, and scleral icterus. Initial laboratory workup revealed elevate…
A 24-year-old Hispanic woman presented to our facility with a two-week history of abdominal pain, nausea, vomiting, diarrhea, jaundice, and scleral icterus. Initial laboratory workup revealed elevated transaminases, direct hyperbilirubinemia, and positive anti-smooth muscle antibody. Liver biopsy confirmed the diagnosis of autoimmune hepatitis and our patient was started on oral prednisone therapy. Her liver enzymes initially began to normalize but then spontaneously started up-trending. She was subsequently readmitted to the hospital for further management, at which time she also complained of palpitations, heat intolerance, and sweating. Laboratory workup revealed hyperthyroidism secondary to Grave's disease. Our patient was not a candidate for methimazole or propylthiouracil treatment due to her hepatic dysfunction, so she was started on hydrocortisone due to its secondary effect of decreased conversion of thyroxine to triiodothyronine. She achieved biochemical remission of her autoimmune hepatitis on this regimen and was transitioned back to oral prednisone therapy. Her liver enzymes normalized once she underwent radioactive iodine ablation of her thyroid. This clinical course suggests that autoimmune hepatitis with concurrent Grave's disease may be refractory to treatment until the underlying hyperthyroid state is corrected.
- Association between genetic polymorphisms of SLCO1B1 and susceptibility to methimazole-induced liver injury. [Journal Article]
- BCBasic Clin Pharmacol Toxicol 2019 Jun 26
- Methimazole (MMI) has been used in the therapy of Grave's disease (GD) since 1954, and drug-induced liver injury (DILI) is one of the most deleterious side effects. Genetic polymorphisms of drug-meta…
Methimazole (MMI) has been used in the therapy of Grave's disease (GD) since 1954, and drug-induced liver injury (DILI) is one of the most deleterious side effects. Genetic polymorphisms of drug-metabolizing enzymes and drug transporters have been associated with drug-induced hepatotoxicity in many cases. The aim of this study was to investigate genetic susceptibility of the drug-metabolizing enzymes and drug transporters to the MMI-DILI. A total of 44 GD patients with MMI-DILI and 118 GD patients without MMI-DILI development were included in the study. Thirty-three single nucleotide polymorphisms (SNPs) in twenty candidate genes were genotyped. We found that rs12422149 of SLCO2B1, rs2032582_AT of ABCB1, rs2306283 of SLCO1B1 and rs4148323 of UGT1A1 exhibited a significant association with MMI-DILI; however, no significant difference existed after Bonferroni correction. Haplotype analysis showed that the frequency of SLCO1B1*1a (388A521T) was significantly higher in MMI-DILI cases than that in the control group (OR = 2.21, 95% CI = 1.11-4.39, P = 0.023), while the frequency of SLCO1B1*1b (388G521T) was significantly higher in the control group (OR = 0.52, 95% CI = 0.29-0.93, P = 0.028). These results suggested that genetic polymorphisms of SLCO1B1 were associated with susceptibility to MMI-DILI. The genetic polymorphism of SLCO1B1 may be important predisposing factors for MMI-induced hepatotoxicity.
- GeneReviews®: Fibrous Dysplasia/McCune-Albright Syndrome [BOOK]
- BOOKUniversity of Washington, Seattle: Seattle (WA)
- Fibrous dysplasia/McCune-Albright syndrome (FD/MAS), the result of an early embryonic postzygotic somatic activating pathogenic variant in GNAS (encoding the cAMP pathway-associated G-protein, Gsα), …
Fibrous dysplasia/McCune-Albright syndrome (FD/MAS), the result of an early embryonic postzygotic somatic activating pathogenic variant in GNAS (encoding the cAMP pathway-associated G-protein, Gsα), is characterized by involvement of the skin, skeleton, and certain endocrine organs. However, because Gsα signaling is ubiquitous, additional tissues may be affected. Café au lait skin macules are common and are usually the first manifestation of the disease, apparent at or shortly after birth. Fibrous dysplasia (FD), which can involve any part and combination of the craniofacial, axial, and/or appendicular skeleton, can range from an isolated, asymptomatic monostotic lesion discovered incidentally to severe disabling polyostotic disease involving practically the entire skeleton and leading to progressive scoliosis, facial deformity, and loss of mobility, vision, and/or hearing. Endocrinopathies include: Gonadotropin-independent precocious puberty resulting from recurrent ovarian cysts in girls and autonomous testosterone production in boys; Testicular lesions with or without associated gonadotropin-independent precocious puberty; Thyroid lesions with or without non-autoimmune hyperthyroidism; Growth hormone excess; FGF23-mediated phosphate wasting with or without hypophosphatemia in association with fibrous dysplasia; and Neonatal hypercortisolism. The prognosis for individuals with FD/MAS is based on disease location and severity.
- Association of HLA-C*03:02 with methimazole-induced liver injury in Graves' disease patients. [Journal Article]
- BPBiomed Pharmacother 2019 Jun 12; 117:109095
- Methimazole (MMI) has been used for the treatment of Graves' Disease (GD) for more than half a century. The MMI treatment has been reported to be associated with hepatotoxicity. Previous studies have…
Methimazole (MMI) has been used for the treatment of Graves' Disease (GD) for more than half a century. The MMI treatment has been reported to be associated with hepatotoxicity. Previous studies have demonstrated that human leukocyte antigen (HLA) genetic polymorphisms were associated with many drugs-induced liver injuries. To investigate HLA genetic susceptibility to MMI-induced liver injury (MMI-DILI), we characterized both HLA class I and class Ⅱ in a well-characterized phenotypic cohort with 40 MMI-DILI cases and 118 MMI-tolerant controls. Among the 40 MMI-DILI cases, 57.5% were women and 50% were cholestatic liver damage with occurring time from days to months after MMI dosing. The frequency of HLA-C*03:02 was 6.7% (5/75) in the MMI-DILI case patients and 6.4% (4/62) in MMI-induced cholestatic/mixed liver damage, which were significantly different from the percentage of 0.4% (1/231) in the MMI-tolerant patients (odds ratio (OR) = 15.4, 95% confidence interval (CI) = 1.77-133.9, adjusted P = 0.0292; OR=14.9, 95% CI=2.38-182.9, adjusted P = 0.0323; respectively). HLA-A*02:01 was also found to be associated with MMI-induced cholestatic/mixed liver injury (OR = 3.13, 95%CI=1.45-6.91, adjusted P = 0.0464). The present study demonstrated that individuals carrying HLA-C*03:02 allele are at increased risk of developing MMI-induced DILI. These results may assist doctors to prevent the occurrence of hepatotoxicity in GD patients receiving MMI.
- An assay for screening xenobiotics for inhibition of rat thyroid gland peroxidase activity. [Journal Article]
- XXenobiotica 2019 Jun 19; :1-5
- 1. A number of chemicals have been shown to produce disruption of the thyroid gland, resulting in reduced thyroid hormone synthesis, by a mechanism involving inhibition of thyroid peroxidase (TPO) ac…
1. A number of chemicals have been shown to produce disruption of the thyroid gland, resulting in reduced thyroid hormone synthesis, by a mechanism involving inhibition of thyroid peroxidase (TPO) activity (EC 126.96.36.199). 2. An assay was developed for rat thyroid gland microsomal TPO activity, employing L-tyrosine as the physiological substrate, with analysis of the formation of the 3-iodo-L-tyrosine (3MIT) metabolite by ultra-performance liquid chromatography-mass spectrometry-mass spectrometry. 3. Formation of 3MIT was linear with respect to both rat thyroid gland microsomal protein concentration and incubation time, whereas only small quantities of 3,5-diodo-L-tyrosine were formed. 4. Studies were performed with nine known TPO inhibitors. The most potent inhibitors were 3-amino-1,2,4-triazole, ethylene thiourea, methimazole and 6-propyl-2-thiouracil which had IC50 values (i.e. concentration to produce a 50% inhibition of enzyme activity) of 0.059, 0.791, 1.07 and 1.96 μM, respectively, whereas the least potent inhibitor was sodium perchlorate which had an IC50 value of 13,800 µM. 5. For five inhibitors, where literature data were available, the observed IC50 values obtained in this study employing rat thyroid gland microsomes and L-tyrosine as substrate were similar to those previously reported using the spectrophotometric guaiacol oxidation assay.
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- Alterations in atrial ion channels and tissue structure promote atrial fibrillation in hypothyroid rats. [Journal Article]
- EEndocrine 2019 Jun 07
- CONCLUSIONS: AERP shortening due to altered protein levels of ion channels and atrial structural changes increased the susceptibility to AF in hypothyroidism. Thyroid replacement therapy could prevent electrical and structural remodeling under hypothyroid condition.