Biomedical subjects

J Chen

Publications and source records attributed to J Chen.

At least 937 records · Page 52Linked to original sources

PubMed2000

A recent outbreak of human immunodeficiency virus type 1 infection in southern China was initiated by two highly homogeneous, geographically separated strains, circulating recombinant form AE and a novel BC recombinant.

New outbreaks of human immunodeficiency virus type 1 (HIV-1) among injecting drug users (IDUs) are spreading in China along heroin trafficking routes. Recently, two separate HIV-1 epidemics among IDUs were reported in Guangxi, Southern China, where partial sequencing of the env gene showed subtype C and circulating recombinant form (CRF) AE. We evaluated five virtually full-length HIV-1 genome sequences from IDUs in Guangxi to determine the genetic diversity and the presence of intersubtype recombinants. Sequence analysis showed two geographically separated, highly homogeneous HIV-1 strains. B/C intersubtype recombinants were found in three IDUs from Baise City, in a mountainous region near the Yunnan-Guangxi border. These were mostly subtype C, with portions of the capsid and reverse transcriptase (RT) genes from subtype B. The subtype B portion of the capsid was located in the N-terminal domain, which has been shown to influence virus core maturation, virus infectivity, and binding to cyclophilin A, whereas the subtype B portion of RT was located in the palm subdomain, which is the active site of the enzyme. These BC recombinants differed from a BC recombinant found in Xinjiang Province in northwestern China. CRF AE strains were found in IDUs from Nanning, the capital of Guangxi, and in IDUs from Pingxiang City near the China-Vietnam border. The AE and BC recombinants were both remarkable for their low interpatient diversity, less than 1% for the full genome. Rapid spread of HIV-1 among IDUs may foster the emergence of highly homogeneous strains, including novel recombinants in regions with multiple subtypes.

Acquired Immunodeficiency Syndrome↗

PubMed2000

Identification and analysis of the K5 gene of Kaposi's sarcoma-associated herpesvirus.

Kaposi's sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8 (HHV-8), belongs to the gammaherpesvirus subfamily and encodes approximately 80 open reading frames (ORFs). Among them are a few candidates for immediate-early genes (e.g., K5). We developed a monoclonal antibody (MAb), 328C7, against the K5 antigen. This MAb reacted with the K5 gene product by immunoscreening of a cDNA library from BCBL-1 cells, and this result was confirmed by transfection of the K5 ORF into Cos-7 cells. After induction of lytic infection by treatment with 12-O-tetradecanoylphorbol-13-acetate, MAb 328C7 reacted with an antigen in the cytoplasm of BCBL-1 and BC-3 cells as early as after 4 h of induction. Immunoelectron microscopy showed that the K5 antigen was situated mainly in the endoplasmic reticulum but was not present on the virion or in the nucleus. Northern blotting with a K5-specific probe revealed a single transcript of 1.2 kb, while Western blotting showed the antigen to be a 36-kDa polypeptide. The 5' and 3' ends were then determined by rapid amplification of cDNA, followed by sequencing of RACE products, and a splice was revealed upstream of the K5 ORF. K5 expression was unaffected by the respective DNA and protein synthesis inhibitors phosphonoformic acid and cycloheximide plus actinomycin D, confirming its immediate-early nature. Transient-transfection assays showed that the K5 promoter was transactivated by ORF 50 (KSHV Rta), a homolog of Epstein-Barr virus Rta, but the K5 gene product exhibited no transregulation of its own promoter or those of DNA polymerase and the human immunodeficiency virus type 1 long terminal repeat. This is the first such analysis of an immediate-early gene product; determination of its specific biological function requires further investigation.

Animals↗

PubMed2000

Brome mosaic virus polymerase-like protein 2a is directed to the endoplasmic reticulum by helicase-like viral protein 1a.

Brome mosaic virus (BMV), a positive-strand RNA virus in the alphavirus-like superfamily, encodes RNA replication proteins 1a and 2a. 1a contains a C-terminal helicase-like domain and an N-terminal domain implicated in viral RNA capping, and 2a contains a central polymerase-like domain. 1a and 2a colocalize in an endoplasmic reticulum (ER)-associated replication complex that is the site of BMV-specific RNA-dependent RNA synthesis in plant and yeast cells. 1a also localizes to the ER in the absence of 2a or viral RNA replication templates. To investigate the determinants of 2a localization, we fused 2a to the green fluorescent protein (GFP), creating a functional GFP-2a fusion that supported BMV RNA replication and subgenomic mRNA transcription. In the absence of 1a, the GFP-2a fusion was found to be diffused throughout the cytoplasm and in punctate spots not associated with any cytoplasmic organelle so far tested. Formation of these spots was dependent on the C-terminal half of 2a and may represent aggregation of a fraction of 2a. When coexpressed with 1a, GFP-2a colocalized with 1a and ER-resident protein Kar2p in a partial or complete ring around the nucleus. Consistent with these results, cell fractionation showed that both the GFP-2a fusion and wild-type (wt) 2a remained soluble when expressed alone, while in cells coexpressing 1a, most of the GFP-2a fusion or wt 2a cofractionated with 1a in the rapidly sedimenting membrane fraction. Deletion analysis showed that the N-terminal 120-amino-acid segment of 2a, containing one of two 2a regions previously shown to interact with 1a, was necessary and sufficient for 1a-directed localization of GFP-2a derivatives to the ER. These results suggest that 1a, which also interacts independently with the ER and viral RNA, is a key organizer of RNA replication complex assembly.

Biological Transport↗

PubMed2000

Hepatocyte-specific mutation establishes retinoid X receptor alpha as a heterodimeric integrator of multiple physiological processes in the liver.

A large number of physiological processes in the adult liver are regulated by nuclear receptors that require heterodimerization with retinoid X receptors (RXRs). In this study, we have used cre-mediated recombination to disrupt the mouse RXRalpha gene specifically in hepatocytes. Although such mice are viable, molecular and biochemical parameters indicate that every one of the examined metabolic pathways in the liver (mediated by RXR heterodimerization with PPARalpha, CARbeta, PXR, LXR, and FXR) is compromised in the absence of RXRalpha. These data demonstrate the presence of a complex circuitry in which RXRalpha is integrated into a number of diverse physiological pathways as a common regulatory component of cholesterol, fatty acid, bile acid, steroid, and xenobiotic metabolism and homeostasis.

Animals↗

PubMed2000

Arginine N-methyltransferase 1 is required for early postimplantation mouse development, but cells deficient in the enzyme are viable.

Protein arginine N-methyltransferases have been implicated in a variety of processes, including cell proliferation, signal transduction, and protein trafficking. In this study, we have characterized essentially a null mutation induced by insertion of the U3betaGeo gene trap retrovirus into the second intron of the mouse protein arginine N-methyltransferase 1 gene (Prmt1). cDNAs encoding two forms of Prmt1 were characterized, and the predicted protein sequences were found to be highly conserved among vertebrates. Expression of the Prmt1-betageo fusion gene was greatest along the midline of the neural plate and in the forming head fold from embryonic day 7.5 (E7.5) to E8.5 and in the developing central nervous system from E8.5 to E13.5. Homozygous mutant embryos failed to develop beyond E6.5, a phenotype consistent with a fundamental role in cellular metabolism. However, Prmt1 was not required for cell viability, as the protein was not detected in embryonic stem (ES) cell lines established from mutant blastocysts. Low levels of Prmt1 transcripts (approximately 1% of the wild-type level) were detected as assessed by a quantitative reverse transcription-PCR assay. Total levels of arginine N-methyltransferase activity and asymmetric N(G), N(G)-dimethylarginine were reduced by 85 and 54%, respectively, while levels of hypomethylated substrates were increased 15-fold. Prmt1 appears to be a major type I enzyme in ES cells, and in wild-type cells, most substrates of the enzyme appear to be maintained in a fully methylated state.

Amino Acid Sequence↗

PubMed2000

FHL2 (SLIM3) is not essential for cardiac development and function.

LIM domain-containing proteins play critical roles in vertebrate development and cellular differentiation. Recently, four members of the four and one-half LIM protein (FHL) family have been identified and cloned. One of these, FHL2, is expressed in a restricted manner in the cardiovascular system throughout development into adulthood, suggesting that FHL2 may play an important role in cardiovascular development and function. Here we describe the generation and analysis of mice carrying a null mutation of the FHL2 gene. FHL2-deficient mice are viable and maintain normal cardiac function both before and after acute mechanical stress induced by aortic constriction. These data suggest that FHL2 is not essential for cardiac development and function.

Animals↗

PubMed2000

Crk1, a novel Cdc2-related protein kinase, is required for hyphal development and virulence in Candida albicans.

Both mitogen-activated protein kinases and cyclin-dependent kinases play a role in hyphal development in Candida albicans. Using an oligonucleotide probe-based screen, we have isolated a new member of the Cdc2 kinase subfamily, designated Crk1 (Cdc2-related kinase). The protein sequence of Crk1 is most similar to those of Saccharomyces cerevisiae Sgv1 and human Pkl1/Cdk9. In S. cerevisiae, CRK1 suppresses some, but not all, of the defects associated with an sgv1 mutant. Deleting both copies of CRK1 in C. albicans slows growth slightly but leads to a profound defect in hyphal development under all conditions examined. crk1/crk1 mutants are impaired in the induction of hypha-specific genes and are avirulent in mice. Consistent with this, ectopic expression of the Crk1 kinase domain (CRK1N) promotes filamentous or invasive growth in S. cerevisiae and hyphal development in C. albicans. The activity of Crk1 in S. cerevisiae requires Flo8 but is independent of Ste12 and Phd1. Similarly, Crk1 promotes filamentation through a route independent of Cph1 and Efg1 in C. albicans. RAS1(V13) can also activate filamentation in a cph1/cph1 efg1/efg1 double mutant. Interestingly, CRK1N produces florid hyphae in ras1/ras1 strains, while RAS1(V13) generates feeble hyphae in crk1/crk1 strains.

Amino Acid Sequence↗

PubMed2000

Mooren's ulcer in China: a study of clinical characteristics and treatment.

AIMS: To investigate the clinical characteristics and compare the effects of several methods of treatment of Mooren's corneal ulcer. METHODS: 550 consecutive cases of Mooren's corneal ulcer were analysed in patients, including age, sex, laterality of eye, ulcer location, perforative rate, cure rate of surgeries, recurrent rate, the effects of conjunctiva excision, lamellar keratoplasty (LKP), and LKP plus 1% cyclosporin A eye drops. RESULTS: The average age of onset was 48.4 years of age. The ratio of males to females was 1:0. 74. 165 (30%) cases had the disease bilaterally, of which 52 (31.5%) occurred in the young age group and 113 (68.5%) in the old age group. Ulcers of 501 eyes (70.1%) were located at the limbus of the palpebral fissure. The perforation rate was 13.3%, with perforation of 41 eyes (43.2%) occurring in the young age group and 54 (56.8%) in the old age group. Postoperative recurrence rate was 25.6%. The cure rate of the first procedure of LKP plus 1% cyclosporin A eye drops was 73.7%. The final cure rate was 95.6%, and the postoperative preservation rate of the eye globe was 99.7%. CONCLUSION: This primary study provided the clinical characteristics of patients with Mooren's corneal ulcer in China. LKP plus 1% cyclosporin A eye drops was an effective treatment.

Administration, Topical↗

PubMed2000

Evidence for conserved tRNA genes in the 16S-23S rDNA spacer sequence and two rrn operons of Xylella fastidiosa.

The 16S-23S rDNA spacer of the type strain (ATCC 35879) of Xylella fastidiosa was amplified by PCR, cloned, and sequenced. The spacer sequence (455 bp) contains two tRNA (tRNA(ala) and tRNA(ile)) genes. Identical tRNA genes were also found in the 16S-23S spacer sequences of all the 51 strains of X. fastidiosa retrieved from the GenBank database. At this particular locus, the gene order of tRNA(ala)-tRNA(ile) is conserved among all the studied strains of Xylella and Xanthomonas, and different from those of other bacteria. Sequence analysis showed that Xanthomonas is the most closely related genus. Results from restriction endonuclease analysis suggested the presence of two rrn operons in the genome of a Xylella fastidiosa Pierce's disease strain.

Base Sequence↗

PubMed2000

Coincident microvillar actin bundle disruption and perinuclear actin sequestration in anoxic proximal tubule.

The present studies investigated acute disruption of microvillar actin cytoskeleton and actin association with other cytoskeletal components in ATP-depleted rabbit proximal tubular cells. Video-enhanced differential-interference contrast microscopy and confocal microscopy were used to follow the fate of F-actin during the disruption of microvilli. Within individual cells, all microvilli collapsed simultaneously. Microvillar actin filaments underwent a parallel decrease in length. Using a sequential cytoskeletal extraction protocol and electron microscopy, we revealed in the present studies the coincident sequestration of a distinct, perinuclear pool of actin that was primarily absent in control cells. Actin sequestration progressed in a duration-dependent manner, occurring as early as 15 min of anoxia when cellular ATP dropped to <5% of control level. Phalloidin staining and depolymerization treatment showed the majority (>90%) of this sequestered actin to be F-actin. A microvillar actin bundling protein villin was also sequestered in the same perinuclear complex of anoxic proximal tubules. In conclusion, the present results demonstrate a coincident microvillar actin bundle disruption and the perinuclear sequestration of F-actin in ATP-depleted proximal tubular cells.

Actins↗

PubMed2000

pH-sensitivity of fast responsive superporous hydrogels.

Stimuli-sensitive hydrogels (or smart hydrogels) are hydrogels that swell or shrink in response to small changes in environmental conditions in which they are placed. While the extent of swelling or shrinking may be large, the kinetics of such changes is slow, since the diffusion of water into and out of the hydrogel is a slow process. To obtain fast responses, we have prepared superporous hydrogels (SPHs) that can swell or shrink extremely fast regardless of their dimensions. The swelling and shrinking are orders of magnitude faster than expected for a nonporous hydrogel of the same dimensions. Water molecules are taken up into the SPHs by capillary forces, and this makes water uptake much faster than diffusion. The swelling ratio of the poly(acrylamide-co-acrylic acid) (p(AM-co-AA)) SPHs was dependent on the pH and ionic strength of the medium. The effect of pH was most pronounced and the effect of ionic strength was observed at all pH values. SPHs made at pH around 5 showed transient maximum swelling when exposed to pH 1.2 medium due to the transient low hydrogen ion concentration inside the swelling SPHs. The p(AM-co-AA) SPHs showed repeated swelling and shrinking by alternating the medium pH between 1.2 and 7.5, and the changes in swelling ratio was quite fast occurring in a matter of a minute. This fast sensitivity may make the stimuli sensitive hydrogels useful in many applications not previously possible. These materials can be used for applications where a single-piece hydrogel is more advantageous than hydrogel microparticulates.

Acrylamides↗

PubMed2000

The role of pre-injury IQ in the determination of intellectual impairment from traumatic head injury.

The subjects were 17 head trauma patients whose pre-injury IQ and post-injury IQ scores on the Chinese Revised Version of the Wechsler Adult Intelligence Scale (WAIS-RC) were collected and analyzed. All patients had a neuroradiological imaging study. Changes in IQ scores were compared with neuroradiological findings and clinical determinations on the presence or absence of intellectual impairment from head trauma that were made by neuropsychiatrists without knowledge of pre-injury IQ scores. Thirteen patients were clinically determined not to have suffered intellectual impairment, primarily because their post-injury IQs on the WAIS-RC were higher than 70. However, 3 of the 13 had significantly higher pre-injury IQ scores, and they also showed brain damage on CT or MRI. Consideration of pre-injury IQ can improve the determination of intellectual impairment from head injury.

Adult↗

PubMed2000

Evaluation of electron beam tomographic coronary arteriography with three-dimensional reconstruction in healthy subjects.

In this study, the authors evaluated the performance characteristics of contrast-enhanced electron-beam tomography (EBT) with three-dimensional reconstruction in defining the coronary artery lumen in healthy subjects. Thirty patients with normal coronary angiograms by selective coronary arteriography (SCA) underwent contrast-enhanced EBT examination. Measured parameters included degree of luminal enhancement, intravascular contrast-to-noise ratio (CNR), and diameter and length of visualized lumen. Ventricular cavity, aortic blood pool, and coronary artery attenuation were found to be significantly different before and after intravenous injection of contrast material (p < 0.001). CNR decreased from proximal to distal segments within each vessel (p < 0.001), with a peak of 11.2 +/- 2.3 occurring in the proximal left anterior descending coronary artery (LAD) to a low of 4.8 +/- 2.0 in the distal left circumflex (LCX). Luminal diameters visualized by EBT had no significant difference with that of SCA (p > 0.05). Therefore, EBT angiography with three-dimensional reconstruction allows for noninvasive coronary arteriography revealing long segments of the major coronary arteries in normal subjects.

Adult↗

PubMed2000

Endotoxin in pooled pericardial blood contributes to the systemic inflammatory response during cardiac surgery.

Although endotoxin has been implicated as an important contributor to the systemic inflammatory response (SIR) during cardiopulmonary bypass (CPB), its source remains unclear. While gut translocation has traditionally been perceived as the primary source of endotoxemia, accumulation of endotoxin in pooled pericardial blood may represent an additional source of endotoxin that is continually reinfused into the CPB circuit. Eighteen patients undergoing primary coronary revascularization procedures were prospectively evaluated. Shed blood pooled in the pericardial space was returned to the CPB circuit through cardiotomy suction catheters at 45 min after placement of the aortic cross-clamp. Simultaneous samples of pooled pericardial and peripheral arterial blood were obtained and analyzed by a limulus amebocyte lysate assay for the determination of endotoxin concentration, and an enzyme-linked immunosorbent assay for tumor necrosis factor (TNF-alpha) levels. Significant elevations in endotoxin were demonstrated in pooled pericardial blood samples compared with arterial blood (3.5 +/- 0.5 vs 0.8 +/- 0.2 pg/ml; p < 0.05). TNF-alpha levels were below the limits of detection in both samples. These data implicate pooled pericardial blood as an important primary source of endotoxin that, when continually reinfused throughout CPB, may contribute to the overall SIR. Because endotoxemia has been identified as an important predictor of adverse outcomes following cardiac surgery, removal of endotoxin antigen in shed pericardial blood, prior to its reinfusion into the CPB circuit, may provide a directed means to improve perioperative outcome without compromising established blood conservation techniques.

Adult↗

PubMed2000

Galactose metabolism by the mouse with galactose-1-phosphate uridyltransferase deficiency.

The ability of mice deficient in galactose-1-phosphate uridyltransferase (GALT) to metabolize galactose was determined in animals weaned to a mouse chow diet for a 4-wk period. When given [14C]galactose intraperitoneally, these animals slowly oxidized the sugar, excreting only 5.5% of the dose as 14CO2 in 4 h, whereas normal animals excreted 39.9%. These results mimic those seen in human galactosemic patients given isotopic galactose. When given 10 micromol of [1-13C]galactose, normal animals excrete small amounts of labeled galactose and galactonate but no galactitol in urine whereas GALT-deficient mice excrete significant amounts of all of these as labeled compounds in urine. When challenged with galactose, only about 20% of the dose is excreted in urine, and even on the chow diet, significant amounts of galactose, galactonate, and galactitol are excreted in urine. These compounds are also found to be present in liver, kidney, and brain, except that galactonate is not found in brain. Galactose-1-phosphate accumulates in red blood cells to levels found in humans exposed to large amounts of galactose, and galactose-1-phosphate is found in increased amounts in liver, kidney, and brain of GALT-deficient animals. There was no difference in the hepatic concentration of uridine diphosphate galactose and uridine diphosphate glucose between normal and GALT-deficient mice. The explanation for the presence of galactose and its conversion products in tissues and urine of affected mice appears to be related to the presence of approximately 1.75% of galactose-containing carbohydrates in the chow, which becomes bioavailable to mice. Despite the presence of galactose and its metabolites in tissues and urine and impaired ability to oxidize the sugar, the GALT-deficient animals are indistinguishable from normal animals and do not exhibit the phenotype of humans with GALT-deficiency galactosemia.

Animals↗

PubMed2000

Galactose breath testing distinguishes variant and severe galactose-1-phosphate uridyltransferase genotypes.

A galactose breath test that quantitates [1-(13)C]galactose conversion to 13CO2 provides information on the whole body galactose oxidative capacity. As there is little information on the relationship between whole body oxidation and the genotype in patients with galactosemia, we measured the 13CO2 excretion for 2 h after administration of [1-(13)C]galactose in 37 patients (3-48 y old) with galactose-1-phosphate uridyltransferase (GALT) deficiency and 20 control subjects (3-37 y old). Eleven patients with the common Q188R/Q188R genotype and no detectable erythrocyte GALT activity eliminated <2% of a bolus of [1-(13)C]galactose as 13CO2 compared with 8.47 to 28.23% in controls. This defines a severe metabolic phenotype. Seven patients with one Q188R allele and a second mutant allele such as L195P, E308K, V151A, M142K, or Q344K and one patient with a K285N/unknown genotype also released <2% as 13CO2 in 2 h. The presence of N314D or S135L as the second mutant allele does not impair total body galactose oxidation, as individuals with the GALT genotype of Q188R/N314D, K285N/N314D, and Q188R/S135L had normal 2-h galactose breath tests. Subjects with S135L/S135L, N314D/N314D, S135L/deltaT2359 as well as other rarer genotypes such as R258C/Y209C, E203K/IVSC-N314D, K285N/T138M, Q188R/D113N, S135L/F171S, R148W/N314D, and IVSC-N314D/N314D oxidized galactose comparable to controls. The dissociation of residual erythrocyte GALT activity and whole body galactose oxidative capacity is exemplified by blacks with a S135L/S135L genotype and absent erythrocyte GALT activity. An oral 2-h [1-(13)C]galactose breath test distinguishes severe and variant GALT genotypes and enables delineation of the extent of impaired galactose metabolism in an array of patients who possess diverse GALT mutations. It may prove to be useful in establishing whether a patient is capable of manifesting disease similar to patients with a Q188R/Q188R genotype.

Adolescent↗

PubMed2000

Effect of tea polyphenols and tea pigments on the inhibition of precancerous liver lesions in rats.

The objective of this study was to investigate the inhibitory effect of tea components, tea polyphenols and tea pigments, on precancerous liver lesions in rats. A rat liver precancerous lesion model was established by multiple low-dosage N-nitrosodiethylamine (NDEA) injections, followed by intraperitoneal CCl4 injection and partial hepatectomy (PH). Tea pigments (0.1%) or tea polyphenols (0.1%) were given to Wistar rats in drinking water during the eight weeks of the experiment. The number and area of glutathione S-transferase Pi-positive foci in the rat liver were used as biomarkers of precancerous liver lesions. Western and Northern blot techniques were used to detect rat liver GST-Pi expression at the protein and mRNA levels. At the end of the experiment, tea polyphenols and tea pigments significantly decreased the number and area of GST-Pi-positive foci that were overexpressed in the NDEA-CCl4-PH-treated rats compared with the positive control group. The results also showed that GST-Pi mRNA and protein expression increased significantly in the NDEA-CCl4-PH-treated group, which is consistent with the changing of GST-Pi-positive foci. Tea pigments and tea polyphenols had an inhibitory effect on the overexpression of GST-Pi mRNA and protein in NDEA-CCl4-PH-treated rats. These results suggest that tea pigments and tea polyphenols are effective in preventing the occurrence and progression of precancerous liver lesions in rats.

Animals↗

PubMed2000

The extracellular domain suppresses constitutive activity of the transmembrane domain of the human TSH receptor: implications for hormone-receptor interaction and antagonist design.

Among glycoprotein hormone receptors the TSH receptor (TSHR) is the most susceptible to constitutive activation by mutations in various regions of the molecule, including mutations in the extracellular domain (ECD) and extracellular loops of the transmembrane domain (TMD). To understand the role of the ECD in TSHR activation we have tested several TSHR constructs with major deletions of the ECD. Previous studies reported very low expression of such truncated glycoprotein hormone receptors, which prevented reliable assessment of their ligand-binding and basal constitutive activities. We have eliminated this problem using TSHR tagged at its N-terminus with a hemagglutinin tag (HA) recognized by the HA-specific monoclonal antibody. Based on such quantitation the TSHR deletion mutant missing 386 N-terminal amino acid residues, constituting 98% of the entire ECD, showed 4-7 fold higher normalized basal activity compared to activity of the corresponding wild-type (WT) TSHR construct. This increase in basal activity was significantly inhibited by linking the common alpha-subunit of glycoprotein hormones at the N-terminus of the truncated TSH receptor. The role of a hypothetical activating fragment (409-418) in TSHR activation was further studied using peptides and mutagenesis of charged residues. This study provides important evidence supporting the "two-state" model of TSHR activation and the potential role of proteolytic cleavage for receptor activation. Accordingly, the mechanism of hormone-induced receptor activation is dependent, at least in part, on the elimination of inhibitory interactions within the receptor. Such intra-molecular inhibition of TSHR may include electrostatic interactions between the ECD and extracellular loops of TMD. Moreover, the truncated, constitutively active receptors described herein provide new insights valuable in the design of TSHR antagonists.

Animals↗