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Biomedical subjects

H Y Lin

Publications and source records attributed to H Y Lin.

At least 109 records · Page 6Linked to original sources
PubMed1994

The types II and III transforming growth factor-beta receptors form homo-oligomers.

Affinity-labeling experiments have detected hetero-oligomers of the types I, II, and III transforming growth factor beta (TGF-beta) receptors which mediate intracellular signaling by TGF-beta, but the oligomeric state of the individual receptor types remains unknown. Here we use two types of experiments to show that a major portion of the receptor types II and III forms homo-oligomers both in the absence and presence of TGF-beta. Both experiments used COS-7 cells co-transfected with combinations of these receptors carrying different epitope tags at their extracellular termini. In immunoprecipitation experiments, radiolabeled TGF-beta was bound and cross-linked to cells co-expressing two differently tagged type II receptors. Sequential immunoprecipitations using anti-epitope monoclonal antibodies showed that type II TGF-beta receptors form homo-oligomers. In cells co-expressing epitope-tagged types II and III receptors, a low level of co-precipitation of the ligand-labeled receptors was observed, indicating that some hetero-oligomers of the types II and III receptors exist in the presence of ligand. Antibody-mediated cross-linking studies based on double-labeling immunofluorescence explored co-patching of the receptors at the cell surface on live cells. In cells co-expressing two differently tagged type II receptors or two differently tagged type III receptors, forcing one receptor into micropatches by IgG induced co-patching of the receptor carrying the other tag, labeled by noncross-linking monovalent Fab'. These studies showed that homo-oligomers of the types II and III receptors exist on the cell surface in the absence or presence of TGF-beta 1 or -beta 2. In cells co-expressing types II and III receptors, the amount of heterocomplexes at the cell surface was too low to be detected in the immunofluorescence co-patching experiments, confirming that hetero-oligomers of the types II and III receptors are minor and probably transient species.

Affinity Labels↗
PubMed1994

The transforming growth factor beta type II receptor can replace the activin type II receptor in inducing mesoderm.

The type II receptors for the polypeptide growth factors transforming growth factor beta (TGF-beta) and activin belong to a new family of predicted serine/threonine protein kinases. In Xenopus embryos, the biological effects of activin and TGF-beta 1 are strikingly different; activin induces a full range of mesodermal cell types in the animal cap assay, while TGF-beta 1 has no effects, presumably because of the lack of functional TGF-beta receptors. In order to assess the biological activities of exogenously added TGF-beta 1, RNA encoding the TGF-beta type II receptor was introduced into Xenopus embryos. In animal caps from these embryos, TGF-beta 1 and activin show similar potencies for induction of mesoderm-specific mRNAs, and both elicit the same types of mesodermal tissues. In addition, the response of animal caps to TGF-beta 1, as well as to activin, is blocked by a dominant inhibitory ras mutant, p21(Asn-17)Ha-ras. These results indicate that the activin and TGF-beta type II receptors can couple to similar signalling pathways and that the biological specificities of these growth factors lie in their different ligand-binding domains and in different competences of the responding cells.

Activin Receptors↗
PubMed1994

Thyroid hormone potentiates the antiviral action of interferon-gamma in cultured human cells.

Human interferon-gamma (hIFN gamma) exhibits a number of biological effects, including antiviral activity in homologous cells. The antiviral activity of recombinant (r) hIFN gamma, estimated by inhibition of vesicular stomatitis virus yield, was potentiated up to 120-fold in human fibroblast (BG-9) cells exposed to free L-T4 (0.5 x 10(-10) mol/L). Thyroid hormone alone did not induce the antiviral state in BG-9 cells. L-T3 also potentiated the antiviral action of rhIFN gamma, but D-T4 and D-T3 were ineffective. The antiviral effect of hIFN alpha in BG-9 cells was not influenced by thyroid hormone. Exposure of rhIFN gamma-treated BG-9 cells to L-T4 for only 3 h was sufficient to potentiate hIFN gamma-mediated antiviral activity. Similar potentiation by L-T4 of the antiviral effect of rhIFN gamma in HeLa cell cultures was also observed. Although the mechanism of potentiation of rhIFN gamma action by thyroid hormone is incompletely understood, the absence of antiviral activity of thyroid hormone alone indicates that the iodothyronine effect does not depend upon hormonal action on genes able to be stimulated by IFN gamma.

Antiviral Agents↗
PubMed1994

Truncation of the porcine calcitonin receptor cytoplasmic tail inhibits internalization and signal transduction but increases receptor affinity.

A series of mutant porcine calcitonin receptors with progressively truncated carboxy termini have been expressed in COS and HEK 293 cells. All forms of the receptor, including those totally lacking the cytoplasmic tail, were able to bind 125I-labeled salmon calcitonin. However, removal of C-terminal domains resulted in multiple functional changes in the receptor. First, compared with the wild type receptor, affinity of binding of salmon calcitonin was increased for truncated receptors, whether determined in intact transfected cells or in cell membranes. Second, internalization of the ligand-receptor complex was greatly attenuated for mutants truncated by 44 or 83 amino acids but not for an intermediate form truncated by 63 amino acids. Third, truncation affected signal transduction, which for the porcine calcitonin receptor occurs by generation of intracellular cAMP and Ca2+. The magnitude of adenylate cyclase responses was much reduced for the same mutants defective in internalization. Under conditions where expression of each receptor form was approximately equal, the magnitude of intracellular Ca2+ responses was decreased by C-terminal truncation. These results draw attention to the functional significance of the cytoplasmic tail of the porcine calcitonin receptor and suggest intramolecular interactions between the carboxy terminus and other receptor domains and/or cellular regulatory elements.

Amino Acid Sequence↗
PubMed1994

Scleroderma after silicone augmentation mammoplasty: report of a case.

The development of connective tissue diseases in patients who have had silicone gel breast implants has not been previously described in Taiwan. Herein, we report a 44-year-old female patient who underwent a silicone gel breast implant approximately 10 years prior to the onset of scleroderma. She developed generalized sclerosis, severe defective esophageal clearance, and severe reduction of gas exchange with DLco 37% of predicted value. Immunologic tests revealed that the antinuclear antibody titer was 1:2,560 with speckled pattern and positive anti-Scl-70 antibody. In spite of prednisolone and D-penicillamine treatment, her condition deteriorated. However, following the removal of the prosthesis, short-term subjective and objective improvements in both skin lesions and pulmonary function were noted. It is important that plastic surgeons, rheumatologists, and dermatologists, as well as primary care physicians, be aware of the possible association of sclerosis with silicone gel breast implants.

Adult↗
PubMed1994

TGF-beta receptors: structure and function.

The transforming growth factor beta (TGF-beta) superfamily of dimeric polypeptide growth factors regulate cell growth and differentiation and play important roles in embryonic development and the immune response. The molecular cloning of three types of high affinity cell-surface receptors (type I, type II and type III) for these growth factors provide insights into their poorly understood mechanisms of action. Here we focus on the structure of these receptors and on the complex interactions which occur between different receptors that are necessary for ligand-induced signal transduction. The type I and type II receptors are both related transmembrane serine/threonine kinase receptors which may hetero-oligomerize to transduce proper signals. The type III receptor modulates the binding of ligands to the signaling complex of type I and type II receptors. These findings suggest that serine/threonine phosphorylation and heteromeric receptor interactions are important elements of TGF-beta induced signaling.

Animals↗
PubMed1994

[Experience of anesthesia during transthoracic endoscopic sympathectomy for palmar hyperhidrosis: comparison between double-lumen endobronchial tube ventilation and laryngeal mask ventilation].

In the past year we had 36 patients operated for transthoracic endoscopic sympathectomy to treat palmar hyperhidrosis. The first group composed of 17 patients receiving anesthesia with double-lumen endobronchial-tube ventilation from July-92 to April-93, and the second group composed of 19 patients receiving anesthesia with laryngeal mask ventilation from April-93 to August-93. During right lung collapse for sympathectomy, the first group patients' SaO2 (oxygen saturation) decreased from 99.65 +/- 0.62 mmHg (pre-operation) to 95.12 +/- 5.48 mmHg (at cauterization), 95.24 +/- 5.41 mmHg (5 minutes after cauterization) and resumed 99.53 +/- 0.62 mmHg after the procedure completed. During left lung collapse for left side sympathectomy, the same group patients' SaO2 decreased from 99.59 +/- 0.62 mmHg to 97.35 +/- 3.06 mmHg, 97.82 +/- 2.53 mmHg and resumed 99.65 +/- 0.49 mmHg respectively. The second group using laryngeal mask ventilation had SaO2 changes during right side sympathectomy from 99.68 +/- 0.58 mmHg (pre-cauterization) to 99.74 +/- 0.45 mmHg (when cauterization), 99.79 +/- 0.42 mmHg (5 minutes after cauterization) and resumed 99.84 +/- 0.37 mmHg after the procedure completed. During left side sympathectomy the second group patients' SaO2 changed from 99.84 +/- 0.39 mmHg to 99.42 +/- 1.50 mmHg, 99.47 +/- 1.46 mmHg and resumed 99.74 +/- 0.59 mmHg respectively. After 2-Way ANOVA with repeated measures of the SaO2 value, we could see that no matter what side operation, there were differences existed between these two groups (< 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Allopurinol hypersensitivity syndrome.

Allopurinol hypersensitivity syndrome (AHS) is an infrequent but life-threatening adverse reaction of allopurinol therapy. The records of 38 patients with the allopurinol hypersensitivity syndrome evaluated at the Veterans General Hospital-Taipei were reviewed. The clinical pictures included fever, rash, leukocytosis, eosinophilia, impaired renal function and hepatocellular injury. Nine patients died (24%) and the major cause of death was infection. The use of corticosteroids increased neither survival nor mortality rate. Twenty-six percent of patients were treated with allopurinol for asymptomatic hyperuricemia, which was not an established indication of the drug, should be avoided. The most important factor of mortality was toxic epidermal necrolysis (TEN) (p < 0.001 compared with other skin lesions). As there is no way to identify the risk group of patients or to make effective treatment for AHS, the only means of minimizing the incidence of AHS is to limit the allopurinol therapy to accepted indications and to adjust the dosage for the patient's renal function.

Adrenal Cortex Hormones↗
PubMed1993

The transforming growth factor beta receptors types I, II, and III form hetero-oligomeric complexes in the presence of ligand.

Transforming growth factors beta (TGF-beta s) are disulfide-linked dimers. In Rat-1 cells both radioiodinated TGF-beta 1 and -beta 2 bind to and can be chemically cross-linked to type I and II receptors (which are thought to mediate effects of cell growth suppression and gene activation), to type III proteoglycan receptors, and to a novel approximately 50-kDa protein. After detergent solubilization of cells that were cross-linked with radioiodinated TGF-beta, antibodies specific for the type II receptor precipitated labeled receptor types I and III as well as type II. In these cells, the type III receptor is the predominant TGF-beta-binding protein, and antibodies specific for it precipitate mainly this cross-linked receptor. Thus, in the presence of TGF-beta ligand, receptor types II and III and types II and I form heteromeric complexes. The majority of the type III receptor does not associate with receptor types I and II, probably reflecting the relative amounts of the three receptors on the surface of Rat-1 cells. Since TGF-beta 1 but not TGF-beta 2 binds to the exoplasmic domain of the type II receptor in the absence of the type III receptor, and since both TGF-beta 1 and -beta 2 bind with high affinity to the type III receptor, we suggest that TGF-beta 2, and possibly TGF-beta 1, bind initially to the type III receptor. The TGF-beta 2-type III receptor complex would then interact with a type II receptor, thus modulating the affinity of the type II receptor for TGF-beta 2.

Amino Acid Sequence↗
PubMed1993

Growth inhibition by transforming growth factor beta (TGF-beta) type I is restored in TGF-beta-resistant hepatoma cells after expression of TGF-beta receptor type II cDNA.

The growth of human hepatoma Hep 3B cells is potently inhibited by TGF-beta 1 (ID50 = 0.2 ng/ml, 8 pM). A mutant cell line was derived that was not inhibited in growth by TGF-beta 1 at 5 ng/ml (200 pM) and that lacked TGF-beta receptor type II (TGF-beta RII) gene. Transfection of the cloned cDNA for human TGF-beta RII to this mutant cell line restored receptor expression as well as the inhibition in growth by TGF-beta 1. In both wild-type and mutant cells stably transfected with TGF-beta RII cDNA, TGF-beta RII coimmunoprecipitated with TGF-beta receptor type I in the presence of ligand. These experiments provide direct evidence for the role of TGF-beta RII in the inhibitory effect of TGF-beta on growth and suggest that TGF-beta RII acts by means of a heteromeric surface complex with TGF-beta receptor type I.

Affinity Labels↗
PubMed1993

Plasma arginase concentration measured by an enzyme-linked immunosorbent assay (ELISA) in normal adult population.

Human liver arginase has many biological effects on lymphocytes, macrophages, liver cells, and tumor cells, in addition to its major role in the liver urea cycle. We have developed a sandwich enzyme-linked immunosorbent assay (ELISA) method to quantitate arginase concentrations in plasma that can be applied to various body fluids. The sensitivity was 2.5 ng/mL. The coefficients of variation were good both in intra- and inter-assay. Using this method to study the stability of an arginase preparation, we found that plasma arginase was stable for only 1 or 2 days even at temperatures as low as 4 degrees C. The mean plasma level was 41.0 +/- 3.3 ng/mL (mean +/- SE) in 143 normal subjects. There was no age difference in the general population and in the male group. However, in the female group, the plasma arginase level increased with age (p = 0.05). Its biological significance was unclear. As a whole, the ELISA method for the measurement of arginase concentration in the body fluid is convenient and reliable.

Age Distribution↗
PubMed1993

Receptors for the TGF-beta superfamily: multiple polypeptides and serine/threonine kinases.

Members of the transforming growth factor beta (TGF-beta) superfamily of peptide growth factors have profound effects on the growth and differentiation of many cell types. Insights into the poorly understood mechanisms of action of these ligands have come from the recent molecular cloning of two types of high-affinity receptors - type II and type III - for TGF-beta superfamily members. The cell surface expression of the type III receptor, a membrane-bound proteoglycan, appears to modulate the binding of ligand to the type II receptor, which is a transmembrane serine/threonine kinase. These results provide evidence for interactions between different receptor types, and suggest that serine/threonine phosphorylation is an important element in TGF-beta-induced signalling.

Journal Article↗
PubMed1993

The 170-kDa glucose-regulated stress protein is an endoplasmic reticulum protein that binds immunoglobulin.

Anoxia, glucose starvation, calcium ionophore A23187, EDTA, glucosamine, and several other conditions that adversely affect the function of the endoplasmic reticulum (ER) induce the synthesis of the glucose-regulated class of stress proteins (GRPs). The primary GRPs induced by these stresses migrate at 78 and 94 kDa (GRP78 and GRP94). In addition, another protein of approximately 150-170 kDa (GRP170) has been previously observed and is coordinately induced with GRP78 and GRP94. To characterize this novel stress protein, we have prepared an antisera against purified GRP170. Immunofluorescence, Endoglycosidase H sensitivity, and protease resistance of this protein in microsomes indicates that GRP170 is an ER lumenal glycoprotein retained in a pre-Golgi compartment. Immunoprecipitation of GRP170 with our antibody coprecipitates the GRP78 (also referred to as the B cell immunoglobulin-binding protein) and GRP94 members of this stress protein family in Chinese hamster ovary cells under stress conditions. ATP depletion, by immunoprecipitation in the presence of apyrase, does not affect the interaction between GRP78 and GRP170 but results in the coprecipitation of an unidentified 60-kDa protein. In addition, GRP170 is found to be coprecipitated with immunoglobulin (Ig) in four different B cell hybridomas expressing surface IgM, cytoplasmic Ig light chain only, cytoplasmic Ig heavy chain only, or an antigen specific secreted IgG. In addition, in IgM surface expressing WEHI-231 B cells, anti-IgM coprecipitates GRP78, GRP94, as well as GRP170; antibodies against GRP170 and GRP94 reciprocally coprecipitate GRP94/GRP170 as well as GRP78. Results suggest that this 170-kDa GRP is a retained ER lumenal glycoprotein that is constitutively present and that may play a role in immunoglobulin folding and assembly in conjunction or consecutively with GRP78 and GRP94.

Adenosine Triphosphate↗
PubMed1993

Community-based epidemiological study on hyperuricemia in Pu-Li, Taiwan.

A community-based survey to study the prevalence and factors associated with hyperuricemia was carried out by the Yang-Ming Crusade from 1987 to 1988 in Pu-Li Township, Taiwan. A total of 1,738, out of 2,573 registered residents over 30 years of age, were contacted for at least one of the two home-visit interviews or for a fasting blood test. The prevalence of hyperuricemia (> or = 458.2 mumol/L for men; > or = 392.7 mumol/L for women) was 17.3%. The prevalence increased with age. Men had a higher prevalence than women (20.3% vs 14.6%). To study the significant correlates of hyperuricemia, univariate analyses and logistic regression were used. The logistic regression analysis showed that after simultaneously controlling the covariates, four variables were significantly correlated with hyperuricemia: blood pressure, creatinine, triglyceride and organ meat consumption.

Adult↗
PubMed1992

Cloning of a Rab3 isotype predominantly expressed in adipocytes.

We have isolated the cDNA for Rab3D, an additional member of the small molecular weight GTP-binding protein family. Rab3D message is abundant in mouse adipocytes. It is increased during differentiation of 3T3-L1 cells into adipocytes, temporally coincident with the appearance of the insulin-sensitive glucose transporter GLUT4. Rab3D is a close homolog of Rab3A, which is found on the cytoplasmic surface of neurosecretory vesicles and which may be involved in their regulated secretion. Since our previous work showed that in permeabilized adipocytes nonhydrolizable GTP analogs mimic insulin in triggering exocytosis of GLUT4-containing vesicles, Rab3D may be involved in the insulin-induced exocytosis of GLUT4-containing vesicles in adipocytes.

3T3 Cells↗
PubMed1992

Expression cloning and characterization of the canine parietal cell gastrin receptor.

Gastrin is an important stimulant of acid secretion by gastric parietal cells and is structurally related to the peptide hormone cholecystokinin (CCK). The pharmacologic properties of the parietal cell gastrin receptor are very similar to the predominant CCK receptor in the brain, CCK-B. Neither the gastrin nor the CCK-B receptor have been cloned thus far, making it difficult to resolve whether these two receptors are distinct. We have isolated a clone encoding the canine gastrin receptor by screening a parietal cell cDNA expression library using a radioligand-binding strategy. Nucleotide sequence analysis revealed an open reading frame encoding a 453-amino acid protein with seven putative hydrophobic transmembrane domains and significant homology with members of the beta-adrenergic family of G protein-coupled receptors. The expressed recombinant receptor shows the same binding specificity for gastrin/CCK agonists and antagonists as the canine parietal cell receptor. Gastrin-stimulated phosphatidylinositol hydrolysis and intracellular Ca2+ mobilization in COS-7 cells expressing the cloned receptor suggest second-messenger signaling through phospholipase C. Affinity labeling of the expressed receptor in COS-7 cells revealed a protein identical in size to the native parietal cell receptor. Gastrin receptor transcripts were identified by high-stringency RNA blot analysis in both parietal cells and cerebral cortex, suggesting that the gastrin and CCK-B receptors are either highly homologous or identical.

Amino Acid Sequence↗
PubMed1992

Expression cloning of the TGF-beta type II receptor, a functional transmembrane serine/threonine kinase.

A cDNA encoding the TGF-beta type II receptor protein has been isolated by an expression cloning strategy. The cloned cDNA, when transfected into COS cells, leads to overexpression of an approximately 80 kd protein that specifically binds radioiodinated TGF-beta 1. Excess TGF-beta 1 competes for binding of radioiodinated TGF-beta 1 in a dose-dependent manner and is more effective than TGF-beta 2. The predicted receptor structure includes a cysteine-rich extracellular domain, a single hydrophobic transmembrane domain, and a predicted cytoplasmic serine/threonine kinase domain. A chimeric protein containing the intracellular domain of the type II receptor and expressed in E. coli can phosphorylate itself on serine and threonine residues in vitro, indicating that the cytoplasmic domain of the type II receptor is a functional kinase. This result implicates serine/threonine phosphorylation as an important mechanism of TGF-beta receptor-mediated signaling.

Amino Acid Sequence↗