Search PubMed⌕ Search

Biomedical subjects

H Y Lin

Publications and source records attributed to H Y Lin.

At least 127 records · Page 7Linked to original sources
PubMed1992

Expression cloning of TGF-beta receptors.

Using a powerful expression cloning method in COS cells, we have cloned the TGF-beta types II and III receptors. The type III TGF-beta receptor is a membrane-bound proteoglycan with a core protein of about 110 kDa. Stable expression of the type III receptor in L6 myoblasts leads to an apparent increase in the ability of the type II receptor to bind iodinated TGF-beta 1. The cloned type II receptor has a predicted protein core of about 60 kDa with a cysteine-rich extracellular domain, a single transmembrane domain, and a functional serine/threonine kinase domain that is homologous to the activin receptor and to the C. elegans protein daf-1. These results implicate serine/threonine phosphorylation as an important mechanism of TGF-beta action.

Animals↗
PubMed1992

Cloning, characterization, and expression of a human calcitonin receptor from an ovarian carcinoma cell line.

A human ovarian small cell carcinoma line (BIN-67) expresses abundant calcitonin (CT) receptors (CTR) (143,000 per cell) that are coupled, to adenylate cyclase. The dissociation constants (Kd) for the CTRs on these BIN-67 cells is approximately 0.42 nM for salmon CT and approximately 4.6 nM for human CT. To clone a human CTR (hCTR), a BIN-67 cDNA library was screened using a cDNA probe from a porcine renal CTR (pCTR) that we recently cloned. One positive clone of 3,588 bp was identified. Transfection of this cDNA into COS cells resulted in expression of receptors with high affinity for salmon CT (Kd = approximately 0.44 nM) and for human CT (Kd = approximately 5.4 nM). The expressed hCTR was coupled to adenylate cyclase. Northern analysis with the hCTR cDNA probe indicated a single transcript of approximately 4.2 kb. The cloned cDNA encodes a putative peptide of 490 amino acids with seven potential transmembrane domains. The amino acid sequence of the hCTR is 73% identical to the pCTR, although the hCTR contains an insert of 16 amino acids between transmembrane domain I and II. The structural differences may account for observed differences in binding affinity between the porcine renal and human ovarian CTRs. The CTRs are closely related to the receptors for parathyroid hormone-parathyroid hormone-related peptide and secretin; these receptors comprise a distinct family of G protein-coupled seven transmembrane domain receptors. Interestingly, the hCTR sequence is remotely related to the cAMP receptor of Dictyostelium discoideum (21% identical), but is not significantly related to other G protein-coupled receptor sequences now in the data bases.

Amino Acid Sequence↗
PubMed1992

A recombinant calcitonin receptor independently stimulates 3',5'-cyclic adenosine monophosphate and Ca2+/inositol phosphate signaling pathways.

Calcitonin (CT), a polypeptide hormone, regulates calcium homeostasis by activating surface receptors coupled to stimulation of adenylyl cyclase in bone and kidney cells. CT has also been reported to increase cytoplasmic Ca2+ in osteoclasts and renal tubule cells. Signaling pathways activated by a recombinant porcine renal calcitonin receptor transiently expressed in HEK-293 cells were studied. In cells expressing the recombinant CT receptor, salmon CT stimulated cAMP accumulation (EC50, 0.16 nM) and synthesis of inositol phosphates (IP; EC50, 3.7 nM). Two other recombinant receptors, the m1-muscarinic acetylcholine receptor and the LH receptor, activated synthesis of either IP or cAMP, respectively, but not both. Stable expression of the CT receptor in a CT receptor-deficient cell line, M18, restored the cells' ability to increase cytoplasmic Ca2+ in response to salmon CT. These results show that a single recombinant CT receptor can independently activate effector pathways mediated by cAMP and IP/Ca2+.

Animals↗
PubMed1992

Degradation of collagen fibrils by live cells: role of expression and activation of procollagenase.

We have examined the conditions for dissolution by live cells of an extracellular matrix composed of reconstituted type I collagen fibrils, using three different cell types which express varying constitutive or inducible levels of procollagenase and collagenase inhibitor. The two major conclusions from these studies were that (i) expression of collagenase is a necessary but not sufficient requirement for dissolution of the collagen fibrils and that (ii) activation of procollagenase is a rate-limiting step. Cells which secreted high levels of procollagenase dissolved collagen fibrils only to the extent that they were able to activate the enzyme. Cells which also expressed inhibitor failed to activate procollagenase in the culture medium and did not dissolve the collagen fibrils unless procollagenase-activation was assisted by exogenous proteinase activity. Cells that did not express inhibitor ultimately did activate procollagenase but the process was slow and incomplete. Introduction of exogenous proteinase activity either in the form of plasminogen, plasmin, or trypsin stimulated collagen breakdown by several fold. Analysis of the culture medium sampled from such cultures showed that the stimulating effect of exogenous proteinases could be ascribed to three separate, but synergistic events: elevated expression of procollagenase, conversion of procollagenase to active form and inactivation of collagenase inhibitor. Two lines of evidence suggested that the dissolution of collagen fibrils in these cultures was mediated by a collagenase-dependent pathway: (i) the rate of dissolution closely mirrored the level of expression of collagenase and (ii) the process was blocked by inhibitory collagenase-specific antibodies.

Adult↗
PubMed1992

Analysis of one hundred and twenty five patients with primary liver cancer surviving more than five years.

During the period of 1958-1986, a series of 125 patients with pathologically proven hepatocellular carcinoma (HCC) surviving more than 5 years was collected in authors' institute. Thirty seven of them survived more than 10 years, the longest being 30 years. Of the entire series, 55.2% of patients was discovered by screening, 48.0% of patients was subclinical HCC, 80.0% of patients had solitary tumor, and 53.6% of patients had tumor size smaller than 5 cm. Pathological findings revealed that 90.2% of tumor was grade I and II (Edmondson grading) and 81.6% of patients associated with cirrhosis. The serum HBsAg was positive in 63% and anti-HBc in 80% of the patients who had checked the HBV markers. Of the 125 patients, 108 patients received resection, 67 patients were small HCC resection, 41 patients were non-small HCC resection, re-resection for subclinical recurrence or solitary lung metastasis was done in 26 patients with resection. Limited resection amounted to 54.6% of patients with resection. Of the 125 patients, 17 patients received palliative surgery other than resection, including hepatic artery ligation, cannulation, or their combination, etc. Eight out of the 17 patients received second stage resection due to marked shrinkage of tumor. It is concluded that early resection remained the major approach to get a long-term survivor, re-resection for subclinical recurrence is also of proved merit. Resection of huge tumor is still useful but less effective. Cyto-reduction and sequential resection is a new trend. Primary liver cancer (PLC) has long been recognized as incurable malignancy with extremely low 5-year survival rate. According to the cancer statistics in the United States, the relative 5-year survival rates for patients with PLC was 2% in 1960-1963, 3% in 1970-1973, 4% in 1974-1976, 3% in 1977-1980 and 5% in 1981-1986. Patients with PLC survived more than 5 years were rarely reported in the literature. In 1971, Curutchet collected worldwide data from 45 authors covering the period for 65 years (1905-1970), only 45 patients with PLC were found to be 5-year survivors. Thanks to the progress in tumor markers, particularly alpha fetoprotin (AFP) and new localization measurements, diagnosis and treatment are possible in subclinical stage. Based on combined strategies to the treatment of PLC including resection of small liver cancer, re-resection of subclinical recurrence after curative resection, multimodality treatment, and sequential resection after shrinkage of tumor, the 5-year survival of PLC has gradually increased.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Linkage of faulty major histocompatibility complex class I to autoimmune diabetes.

Pancreatic islet cells are the targets of an autoimmune response in type I diabetes. In the nonobese diabetic (NOD) mouse model of autoimmune diabetes, expression of major histocompatibility complex (MHC) class I proteins was inversely correlated with diabetes; in this mouse a mutation in the MHC class II-linked gene for the putative MHC class I peptide transporter was also present. Mice deficient in MHC class I expression because they do not produce beta 2-microglobulin also developed late onset autoimmune diabetes. In cells from humans with type I diabetes expression of MHC class I was decreased; subsets of prediabetics categorized as most likely to become hyperglycemic also had low MHC class I. T cell responses to self antigens are faulty in diabetics. In sets of genetically identical twins that are discordant for diabetes, the defect appeared to reside with the antigen presenting cell. Thus, a lack of surface MHC class I protein is associated with autoimmune diabetes; the concomitant defect in antigen presentation may impair the development of self tolerance, which could result in autoimmune disease.

Animals↗
PubMed1991

Expression cloning and characterization of the TGF-beta type III receptor.

The rat TGF-beta type III receptor cDNA has been cloned by overexpression in COS cells. The encoded receptor is an 853 amino acid protein with a large N-terminal extracellular domain containing at least one site for glycosaminoglycan addition, a single hydrophobic transmembrane domain, and a 41 amino acid cytoplasmic tail with no obvious signaling motif. Introduction of the cDNA into COS cells and L6 myoblasts induces expression of a heterogenously glycosylated 280-330 kd protein characteristic of the type III receptor that binds TGF-beta 1 specifically. In L6 myoblasts lacking the endogenous type III receptor, expression of the recombinant receptor leads to an increase in the amount of ligand bound and cross-linked to surface type II TGF-beta receptors. This indicates that the type III receptor may regulate the ligand-binding ability or surface expression of the type II receptor.

Amino Acid Sequence↗
PubMed1991

Expression cloning of an adenylate cyclase-coupled calcitonin receptor.

A calcitonin receptor complementary DNA (cDNA) was cloned by expression of a cDNA library from a porcine kidney epithelial cell line in COS cells. The 482-amino acid receptor has high affinity for salmon calcitonin (dissociation constant Kd approximately 6 nM) and is functionally coupled to increases in intracellular cyclic adenosine monophosphate (cAMP). The receptor shows no sequence similarity to other reported G protein-coupled receptors but is homologous to the parathyroid hormone-parathyroid hormone-related peptide (PTH-PTHrP) receptor, indicating that the receptors for these hormones, which regulate calcium homeostasis, represent a new family of G protein-coupled receptors.

Adenylyl Cyclases↗
PubMed1991

Cloning and functional expression of a vascular smooth muscle endothelin 1 receptor.

By screening a cDNA library derived from the A10 rat vascular smooth muscle cell line for functional expression in COS cells, we have isolated a high-affinity receptor for endothelin 1 (Kd = 476 pM) and endothelin 2. The affinity of the cloned endothelin receptor for endothelin 3 is greater than 100 times less in A10 cells and in a CHO cell line stably transformed by the endothelin receptor cDNA. The 426-amino acid receptor polypeptide has seven putative hydrophobic transmembrane domains and is presumed to be a member of the family of guanine nucleotide-binding regulatory (G) protein-coupled receptors. Microinjection of in vitro transcripts of the cloned cDNA into CHO cells confers a transient increase in intracellular calcium in response to endothelin 1, indicating that the receptor is functional and couples to the appropriate G protein(s). RNA analysis reveals high expression in rat lung and heart, tissues known to exhibit binding to iodinated endothelin 1.

Amino Acid Sequence↗
PubMed1991

Production of human interferon-beta by Sendai virus and poly(rI).poly(rC): inhibition by neomycin.

Neomycin inhibits the production of interferon-beta (IFN-beta) in human fibroblast cells in response to Sendai virus or to poly(rI).poly(rC) in a concentration-dependent manner, and to the greatest extent effective when added prior to or up to 2 h after induction. This inhibitory effect is negated when the protein kinase C activator, SC-9, is present during IFN-beta production in response to poly(rI).poly(rC), but not in response to Sendai virus. These results suggest that in human cells both virus and poly(rI).poly(rC) utilize an early neomycin-sensitive signal transduction step for the production of IFN-beta; because neomycin binds specific phosphatidylinositol phosphates, both of these inducers very likely require hydrolysis of these phosphates.

Cell Line↗
PubMed1991

[Cyclosporin A for treatment in nephrotic syndrome of childhood--a preliminary report].

We treated five, three steroid resistant and 2 steroid dependent nephrotic syndrome with oral cyclosporin A and prednisolone. All children received more than eight weeks course of prednisolone, and were in a critically ill status from their nephrotic syndrome and by steroid-toxic side effects. Cyclosporin A was started at 7 mg/kg/day and titrated to maintain serum level of 150-250 ng/ml. Prednisolone was given initially at a dose of 1 mg/kg/day x 1 month, subsequently at a dose of 0.4 mg/kg/day x 1 month, then 0.2 mg/kg/day x 4 months. After a total course of six months, cyclosporin A was tapered to 3.5 mg/kg/day. Prednisolone was maintained at a dose of 0.2 mg/kg/day. Renal biopsies of the 3 steroid resistant children showed membranous glomerulonephritis with focal segmental glomerulosclerosis, focal segmental glomerulosclerosis and IgM nephropathy respectively. These three cases all went into complete remission within four weeks. Among them, one case relapsed twice within one year. Renal biopsies of the two steroid dependent children showed minimal change and focal segmental glomerulosclerosis respectively. These two cases went into complete remission within three weeks sustained up to a year. Side effects of cyclosporin A were observed in one patient with gum hypertrophy and two patients with hirsutism. Other side effects were not found. After cyclosporin A treatment for one year, the renal biopsy of the relapsing patient showed no interstitial fibrosis or tubular atrophy. In conclusion, cyclosporin A was found to be effective in steroid resistant and dependent patients. The duration of cyclosporin A treatment is so far unknown. It needs further evaluation in the future.

Child↗
PubMed1991

[Candida arthritis: report of two cases].

Candida arthritis is extremely rare. However, there has been a steady increase in the incidence of candida arthritis during the last decade because of increasing candida infections in immunocompromised hosts, drug addicts, premature babies, and those who have received prosthetic joint operations or intraarticular injections of steroids. We report herein two cases of candida arthritis: a 27-year-old man with aplastic anemia and transfusional hemosiderosis, and a 60-year-old man with osteoarthritis who received repeated intra-articular injections of steroids. Definite diagnoses were made after repeated smear examinations of synovial fluids. In the first case, candida arthritis occurred about 2 weeks after an antecedent candidemia. Although the arthritis relapsed once due to inadequate antifungal treatment, it was finally successfully treated with systemic amphotericin B, oral ketoconazole and surgical drainage of the synovial fluid. In the second case, it took several months to make the diagnosis. The patient was also treated with amphotericin B, ketoconazole, and surgery with a satisfactory outcome. We conclude that since candida arthritis is a slow, less destructive joint infection, it can almost always be resolved. Also, late orthopedic complications can be avoided by early diagnosis and prompt treatment, including aggressive antifungal therapy, adequate drainage and necessary surgical intervention.

Adult↗
PubMed1990

Effect of calmodulin antagonists on the interferon system: induction and action of interferons.

Synthesis of interferon (IFN) in response to Sendai virus and the development of the resulting antiviral state were studied in human (BG-9) and murine (L-929) fibroblast cell cultures in the presence of the calmodulin antagonists, trifluoperazine (TFP) and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). Compared to control cultures, 16-fold and 8-fold more IFN was formed in human and murine cells, respectively, when 10 microM TFP was present in the medium for 24 h prior to IFN induction with Sendai virus. W-7 did not affect IFN production in human cells, but enhanced it in L-929 cells by 4- to 8-fold. TFP inhibited the antiviral state induced by homologous IFN in the two cell systems, and at 20 microM, there was a 3,000-fold increase in vesicular stomatitis virus (VSV) yield. It also reduced the maintenance of the antiviral state in human cells. In contrast, W-7 had no effect on the development of the antiviral state in either of the two cell systems. Thus, calcium-calmodulin dependent cellular processes are involved in both induction of IFN and its action. The several patterns response to TFP and W-7 may reflect different ligand-binding sites on calmodulin.

Animals↗
PubMed1990

Effect of protein kinase C inhibitors on interferon-beta production by viral and non-viral inducers.

Induction of interferon-beta (IFN-beta) in human (BG-9), simian (CV-1) and mouse (L-929) cell lines by Sendai virus and by poly(rI). poly(rC) has been studied for its possible dependence on protein kinase C (PKC) through the use of pharmacological inhibitors (K252a and H-7) of PKC. Exposure of BG-9, CV-1 or L-929 cells to K252a (greater than or equal to 0.025 microM), a staurosporine derivative, 24 h before or after induction of IFN with poly(rI).poly(rC), inhibited by greater than 95% the production of IFN-beta. In contrast, virus-induced IFN production was enhanced threefold or more by K252a in BG-9 and L-929 but not in CV-1 cells. A naphthalene sulphonamide inhibitor of PKC, H-7, at greater than or equal to 5 microM, decreased poly(rI).poly(rC)-induced IFN production in BG-9 and CV-1 cells by 75 to 94%, but had no effect on IFN production in L-929 cells. Viral induction of IFN was not affected significantly by H-7 in BG-9, CV-1 and L-929 cells. In contrast to these results, the calmodulin inhibitor, trifluoperazine (5 to 15 microM) did not affect IFN-beta production by poly(rI).poly(rC) but significantly enhanced IFN production by Sendai virus in both human and murine cell lines. Thus, in human and simian fibroblasts the induction of IFN-beta by poly(rI).poly(rC) appears to be PKC-dependent, whereas viral induction of IFN-beta is not. Results with K252a implicate PKC in non-viral induction of IFN in mouse fibroblasts, as well. Direct measurements of PKC activity in BG-9 cells exposed to several concentrations of K252a showed that the membrane PKC activity is significantly more sensitive to inhibition by K252a than is cytosolic PKC activity. In L-929 cells, K252a inhibited membrane PKC activity similarly, but was less effective as an inhibitor of cytosolic enzyme activity than in BG-9. These studies support an integral role for PKC activity, particularly membrane-associated activity, in non-viral [poly(rI).poly(rC)] induction of IFN-beta in human, simian and mouse fibroblasts.

Animals↗
PubMed1989

Cyclosporine-induced hyperuricemia and gout.

To evaluate the frequency and the pathogenesis of hyperuricemia and gout during cyclosporine therapy, we studied renal-transplant recipients who were treated with either cyclosporine and prednisone (n = 129) or azathioprine and prednisone (n = 168). Among the patients with stable allograft function and serum creatinine concentrations below 265 mumol per liter, hyperuricemia was more common in the cyclosporine group than in the azathioprine group (84 percent vs. 30 percent; P = 0.0001). Gout developed in nine patients (7 percent) in the cyclosporine group, but no episodes occurred in the azathioprine group. Serum urate levels became elevated in 90 percent of the patients in the cyclosporine group who were treated with diuretics, as compared with 60 percent of those not treated with diuretics (P = 0.001); in the azathioprine group, the corresponding values were 47 percent and 15 percent (P = 0.0001). Serum urate levels did not correlate with trough blood cyclosporine levels in a selected subgroup (n = 40) of patients from the cyclosporine group, who were studied from 4 to 96 weeks after transplantation. Detailed studies of urate metabolism in six cyclosporine-treated patients revealed normal turnover rates for urate and decreases in creatinine and urate clearance, as compared with seven control subjects. We conclude that hyperuricemia is a common complication of cyclosporine therapy and is caused by decreased renal urate clearance. Gouty arthritis is the cause of considerable morbidity among renal-transplant recipients who receive cyclosporine.

Adult↗