Biomedical subjects

H Y Song

Publications and source records attributed to H Y Song.

At least 55 records · Page 3Linked to original sources

PubMed1997

Benign biliary strictures associated with recurrent pyogenic cholangitis: treatment with expandable metallic stents.

OBJECTIVE: The purpose of this study was to determine the long-term effectiveness of expandable metallic stents in benign biliary strictures associated with recurrent pyogenic cholangitis and the differences in primary patency of the various types of stents deployed. SUBJECTS AND METHODS: During a 20-month period, 26 metallic stents (19 Gianturco-Rosch Z stents and seven Strecker stents) were used to treat benign biliary strictures associated with recurrent pyogenic cholangitis in 23 patients (11 men and 12 women; mean age, 42 years; range, 30-78 years). Insertion routes were percutaneous transhepatic biliary drainage tracts for 16 stents, T-tube tracts for seven stents, and retrograde endoscopic routes for three stents. The deployed locations were common hepatic or common bile ducts for 11 stents, right or left hepatic ducts for 10 stents, and segmental ducts for five stents. RESULTS: The initial technical success rate was 100%. Two stents in one patient migrated spontaneously. Primary stent patency for the remaining 24 stents was 34 months (range, 3-58 months). Primary stent patency of the Gianturco-Rosch Z and Strecker stents was 50 and 10 months, respectively (p < .05). Primary stent patency for the intrahepatic and extrahepatic ducts was 50 and 18 months, respectively (p = .05). Primary patency rates for all stents at 6, 12, 24, and 36 months were 92%, 75%, 67%, and 46%, respectively. The causes of stent obstruction were recurrent stone or sludge in eight stents and epithelial hyperplasia in five stents. CONCLUSION: We believe that metallic stent placement is not an effective long-term treatment technique for benign biliary stricture associated with recurrent pyogenic cholangitis.

Adult↗

PubMed1996

The tumor necrosis factor-inducible zinc finger protein A20 interacts with TRAF1/TRAF2 and inhibits NF-kappaB activation.

TRAF1 and TRAF2 form an oligomeric complex that associates with the cytoplasmic domains of various members of the tumor necrosis factor (TNF) receptor superfamily. TRAF2 action is required for activation of the transcription factor NF-kappaB triggered by TNF and the CD40 ligand. Here we show that TRAF1 and TRAF2 interact with A20, a zinc finger protein, whose expression is induced by agents that activate NF-kappaB. Mutational analysis revealed that the N-terminal half of A20 interacts with the conserved C-terminal TRAF domain of TRAF1 and TRAF2. In cotransfection experiments, A20 blocked TRAF2-mediated NF-kappaB activation. A20 also inhibited TNF and IL-1-induced NF-kappaB activation, suggesting that it may inhibit NF-kappaB activation signaled by diverse stimuli. The ability of A20 to block NF-kappaB activation was mapped to its C-terminal zinc finger domain. Thus, A20 is composed of two functionally distinct domains, an N-terminal TRAF binding domain that recruits A20 to the TRAF2-TRAF1 complex and a C-terminal domain that mediates inhibition of NF-kappaB activation. Our findings suggest a possible molecular mechanism that could explain A20's ability to negatively regulate its own TNF-inducible expression.

Cell Line↗

PubMed1996

Lacrimal canaliculus obstruction: nonsurgical treatment with a newly designed polyurethane stent.

A newly designed polyurethane stent was used to successfully treat 30 eyes (in 28 patients) with epiphora resulting from obstruction of the lacrimal canaliculus. After stent placement, epiphora resolved in all eyes. During follow-up, epiphora recurred in 20 eyes, but epiphora did not recur and the lacrimal canaliculus was patent in 12 eyes after the stent was removed. The stent appears to be valuable for nonsurgical treatment of obstruction of the lacrimal canaliculus.

Equipment Design↗

PubMed1996

Esophagorespiratory fistulae due to esophageal carcinoma: palliation with a covered Gianturco stent.

PURPOSE: To evaluate therapeutic effects and complications of a covered Gianturco stent for esophagorespiratory fistulae. MATERIALS AND METHODS: Of 95 patients with esophageal carcinomas, 10 had esophagorespiratory fistulae and were treated with a silicone-covered Gianturco stent. The authors retrospectively assessed patients' food intake capacity and delayed problem of the stent. RESULTS: All fistulae were occluded without immediate complications. Two patients could swallow all foods; four, most foods; three soft foods; and one, only liquids. Clinical problems occurred between 1 and 24 weeks in four patients: reopened fistula (n = 1), recurrent fistula (n = 1) (both patients were successfully treated with another esophageal stent), and dyspnea (n = 2) due to tracheal compression by stent and tracheal invasion by tumor (one patient was treated with a tracheal stent). CONCLUSION: A silicone-covered modified Gianturco stent is effective for palliation of esophagorespiratory fistulae caused by esophageal cancer. Simultaneous use of a tracheal stent is recommended for extrinsic tracheal narrowing by the proximal tip of the stent and invasion by tumor.

Bronchial Fistula↗

PubMed1996

Nonsurgical placement of a nasolacrimal polyurethane stent: long-term effectiveness.

PURPOSE: To evaluate the long-term effectiveness of a polyurethane stent in the treatment of obstruction of the lacrimal sac and the nasolacrimal duct. MATERIALS AND METHODS: Fluoroscopically guided placement of a polyurethane nasolacrimal stent was evaluated in 283 obstructed lacrimal systems of 236 patients, with a follow-up period of more than 1 year (range, 52-134 weeks). The obstruction was at the junction between the lacrimal sac and the nasolacrimal duct in 192 systems, at the lacrimal sac in 52, and at the nasolacrimal duct in 39. The causes of obstruction were traumatic in 34 and idiopathic in 249 systems. RESULTS: Stent placement was technically successful in 270 systems (95%). At 7 days after stent placement, 235 (87%) of the 270 systems with successful placement demonstrated complete resolution of epiphora, 27 (10%) had partial resolution, and the remaining eight (3%) had no resolution. There was recurrence in 81 systems due to obstruction of the stent (n = 77) or obstruction of the common canaliculus (n = 4). The recurrence rate was much higher in the systems with obstruction at the lacrimal sac (64%) than in the systems with obstruction at the junction (26%) between the lacrimal sac and nasolacrimal duct or at the nasolacrimal duct (15%). CONCLUSION: Stent placement in the obstructed lacrimal system below the junction between the lacrimal sac and the nasolacrimal duct is valuable as an initial therapy.

Adolescent↗

PubMed1995

Association of a RING finger protein with the cytoplasmic domain of the human type-2 tumour necrosis factor receptor.

A human gene encoding a protein that specifically binds to the intracellular domain of the 75 kDa type-2 tumour necrosis factor (TNF) receptor (TNFR-2IC) has been identified using the yeast-based two-hybrid system. The N-terminal half of the TNF receptor-associated protein (TRAP) contains RING finger and zinc finger motifs often found in DNA-binding proteins including transcription factors. The 2.4 kb TRAP mRNA was barely detectable, if present at all, in lung, and variably expressed in heart, liver, placenta, brain, skeletal muscle, kidney and the pancreas; interestingly, the TRAP was more highly expressed in transformed cell lines than in normal tissues. This observation may be consistent with a role for this TRAP in promoting or regulating cellular proliferation. After in vitro transcription/translation and 35S labelling the TRAP was precipitated using a fusion protein consisting of glutathione S-transferase and the intracellular domain of TNFR-2 (TNFR-2IC), which showed that the two proteins directly interact in a mammalian cell-free system and also that identification of the TRAP was not an artifact of the two-hybrid system. By using truncated TNFR-2ICs for in vitro precipitation of 35S-TRAP, it was shown that the C-terminal half of the TNFR-2IC contains the domain necessary for interaction with TRAP. The TRAP identified in the present study shares considerable homology with, and may be the human homologue of, a mouse protein, TNF receptor-associated factor 2 (TRAF2), that binds mouse TNFR-2.

Amino Acid Sequence↗

PubMed1995

Vascular endothelial cell growth factor promotes tyrosine phosphorylation of mediators of signal transduction that contain SH2 domains. Association with endothelial cell proliferation.

Vascular endothelial cell growth factor (VEGF), an endothelial cell-specific mitogen that plays an important role in angiogenesis, promotes the tyrosine phosphorylation of at least 11 proteins in bovine aortic endothelial cells (BAEC). Proteins immunoprecipitated from lysates of control- and VEGF-stimulated BAEC with antisera to phospholipase C-gamma (PLC-gamma) were fractionated by SDS-polyacrylamide gel electrophoresis and transferred to Immobilon-P. Evaluation of the Western blots with antisera to phosphotyrosine demonstrated that PLC-gamma and two proteins (100 and 85 kDa) that associate with PLC-gamma were phosphorylated in response to VEGF. By using antisera specific to other mediators of signal transduction that contain SH2 domains for immunoprecipitation, it was demonstrated that VEGF promotes phosphorylation of phosphatidylinositol 3-kinase, Ras GTPase activating protein (GAP), and the oncogenic adaptor protein NcK. Proteins of M(r) consistent with the VEGF receptors Flt-1 and Flk-1/KDR were also tyrosine phosphorylated in stimulated cells. Tyrosine-phosphorylated Nck, PLC-gamma, and two GAP-associated proteins, p190 and p62, were in GAP immunoprecipitates of VEGF-stimulated BAEC, and tyrosine-phosphorylated NcK was in phosphatidylinositol 3-kinase immunoprecipitates. These observations suggest that VEGF promotes formation of multimeric aggregates of VEGF receptors with proteins that contain SH2 domains and activate various signaling pathways. VEGF-promoted proliferation of endothelial cells and tyrosine phosphorylation of SH2 domain containing signaling molecules were inhibited by the tyrosine kinase inhibitor genistein.

Adaptor Proteins, Signal Transducing↗

PubMed1995

Identification of a protein with homology to hsp90 that binds the type 1 tumor necrosis factor receptor.

The yeast-based two hybrid has been used to identify a novel protein that binds to the intracellular domain of the type 1 receptor for tumor necrosis factor (TNFR-1IC). The TNF receptor-associated protein, TRAP-1, shows strong homology to members of the 90-kDa family of heat shock proteins. After in vitro transcription/translation and 35S labeling, TRAP-1 was precipitated using a fusion protein consisting of glutathione S-transferase and TNFR-1IC, showing that the two proteins directly interact. The ability of deletion mutants of TNFR-1 to interact with TRAP-1 was tested using the two hybrid system. This showed that the amino acid sequences that mediate binding are diffusely distributed outside of the domain in the C terminus of TNFR-1IC that signals cytotoxicity. The 2.4-kilobase TRAP-1 mRNA was variably expressed in skeletal muscle, liver, heart, brain, kidney, pancreas, lung, and placenta. TRAP-1 mRNA was also detected in each of eight different transformed cell lines. Identification of TRAP-1 may be an important step toward defining how TNFR-1, which does not contain protein tyrosine kinase activity, transmits its message to signal transduction pathways.

Amino Acid Sequence↗

PubMed1995

Myeloid progenitor cell regulatory effects of vascular endothelial cell growth factor.

Vascular endothelial cell growth factor (VEGF) is a ligand for the tyrosine kinase receptor Flk-1/KDR and Flt1 and is considered to be an endothelial cell specific mitogen that plays an important role in angiogenesis. Since Flk-1 mRNA has been detected in primitive and more mature hematopoietic cells, recombinant human VEGF was evaluated for its influence on hematopoiesis, which was assayed as in vitro colony formation by myeloid progenitor cells from human bone marrow. VEGF enhanced colony formation by mature subsets of granulocyte-macrophage and erythroid progenitor cells that had been stimulated with a colony stimulating factor. In contrast, VEGF inhibited colony formation by more immature subsets of granulocyte-macrophage, erythroid and multipotential progenitor cells synergistically stimulated to proliferate with a colony stimulating factor and either steel factor or the ligand for the Flt-3 receptor tyrosine kinase. VEGF produced effects similar to those given above on purified CD34 progenitor cells from bone marrow and VEGF effects were neutralized by VEGF antibodies. However, when assessed for effects on single sorted CD34 cells, VEGF only enhanced or suppressed colony formation by granulocyte-macrophage progenitor cells and the amplitude of the response was less than that observed when populations of these cells were tested. In the single cell assays, VEGF had no effect on colony formation by erythroid or multipotential progenitors. These results suggest that the effects of VEGF, which were not species specific, are mediated by both direct and indirect actions on the progenitors and thereby identify new activities for this important factor.

Animals↗

PubMed1995

Nonsurgical placement of a nasolacrimal polyurethane stent.

PURPOSE: To describe the placement of a nasolacrimal polyurethane stent with a new introducer set and hook. MATERIALS AND METHODS: The authors designed a soft polyurethane stent, an introducer that does not require balloon dilation, and a hook that can remove a ball-tipped guide wire from the inferior nasal meatus under fluoroscopic guidance. The stent was placed in 51 lacrimal systems in 44 outpatients who had complete obstruction of the lacrimal sac or nasolacrimal duct. RESULTS: Stent placement was technically successful and well tolerated in 50 of 51 nasolacrimal systems. The procedure lasted an average of 16 minutes (range, 10-33 minutes). After stent placement, 47 of 50 eyes showed complete resolution of epiphora, and the other three showed partial resolution. During follow-up, no stents migrated, and one stent became blocked. The stent was reopened by means of forceful irrigation of saline solution through the superior punctum. CONCLUSION: Placing a polyurethane nasolacrimal stent by use of the new introducer and hook simplifies the technique, shortens operating time, reduces cost, and makes the procedure well tolerated by patients.

Adolescent↗

PubMed1995

Self-expandable metallic stents in high-risk patients with benign prostatic hyperplasia: long-term follow-up.

PURPOSE: To evaluate the long-term clinical utility of self-expandable metallic Z stents in benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: Under fluoroscopic guidance, 14 multiple-connected Z stents (10 mm in diameter fully expanded, 30-60 mm in length) were placed in 13 patients with bladder obstruction from BPH and high operative risks. The stents were placed in the prostatic urethra with 2-20-mm protrusion into the urinary bladder in six patients (group A) and entirely within the prostatic urethra in seven patients (group B). RESULTS: Eleven of 13 patients could void immediately, and the other two patients with atonic bladder voided within 8 weeks. Maximum urine flow rates just after stent placement were 8-27 mL/sec. Two patients died of unrelated causes within 2 months. During the follow-up period (mean, 37 months) in the other 11 patients, all patients in group A but none in group B underwent surgery owing to stone formation where the stent protruded into the bladder. CONCLUSION: Expandable Z stents are effective in patients with BPH but should not protrude into the urinary bladder because of stone formation.

Aged↗

PubMed1995

Preoperative chemoradiotherapy for locoregional esophageal cancer: preliminary report.

Conventional treatment of esophageal cancer with surgery or radiation alone has afforded few long-term survivors. In order to improve outcome and determine the efficacy of a combined modality approach, this prospective study was performed. Between May 1993 and August 1994, 27 patients with loco-regional squamous cell carcinoma of the esophagus were treated with 2 courses of combined fluorouracil(1000mg per square meter of body-surface area daily for 5 days) and cisplatin(60mg per square meter on the first day)(D1 and D29) plus 48Gy of radiation therapy(RT) over 4 weeks. A transhiatal esophagectomy was planned 3-4 weeks after chemoradiotherapy. Twenty-seven patients completed a full course of therapy. Clinical response was evaluable in 26 patients: 22 patients showed improvement and relief from dysphagia, 2 patients stable disease, and 2 patients progression. One patient died of sepsis 1 week after completion of chemoradiotherapy and was excluded from the analysis. Ten patients underwent operation after chemoradiation. Of them, 5 showed complete histologic response. One of the complete responders died of recurred disease 8.5months after operation, the other 2 patients died of sudden death, and sepsis from wound deheiscence 7 days after operation, respectively. Nine patients refused operation because of excellent relief of their dysphagia and 6 patients were denied because of disease progression(2), fear of operations(2), old age and family member's disapprovement(1), and underlying liver cirrhosis(1). The last one patient was awaiting for operation. Of 13 patients who refused or denied operation, 6 patients finished further chemotherapy and radiatherapy(external radiation 1200 cGy+intracavitary radiation 900 cGy, 2 cycles of 5FU+cisplatin). This intensive preoperative chemoradiotherapy is feasible, and allows for a high rate of resectability and a high rate of complete pathologic response in a locoregional esophageal cancer. Toxicity is considerable but manageable. This study warrants further investigation.

Adult↗

PubMed1995

[Effect of angiotensin II on vasopressin gene transcription in the hypothalamus of rats].

Experiments were carried out in male Sprague-Dawley rats. 3'-end digoxigenin-labeled 26 bp oligonucliotide probe was used to detect the vasopressin (AVP) mRNA in the hypothalamus. Dot blotting technique was used in the investigation of AVP gene transcription level. The results showed that continuous intracerebroventricular administration (i.c.v.) of angiotensin II at a rate of 0.2 nmol/h for 2 days by using a miniosmotic pump resulted in a significant increase in daily water intake. An increase of AVP gene transcription level in the hypothalamus was also observed, but statistically insignificant. When daily water intake was limited (25 ml/d), continuous i.c.v. infusion of ANG II caused a significant increase in hypothalamic AVP gene transcription. It was also observed that hypothalamic AVP gene transcription level increased after salt loading and dehydration. However, intraperitoneal application of angiotensin converting enzyme inhibitor captopril (5 mg/(kg.d)) or i.c.v. nonpeptide angiotensin II receptor antagonist Dup753 (0.9 nmol/h) did not attenuate the increase of AVP gene transcription level induced by salt loading or dehydration. It is therefore suggested that the administration of ANG II enhances AVP gene transcription in the hypothalamus, especially when water intake is limited. However, this increase does not involve the participation of endogenous ANG II.

Angiotensin II↗

PubMed1994

Aggregation of the intracellular domain of the type 1 tumor necrosis factor receptor defined by the two-hybrid system.

The yeast-based two hybrid system has been used to determine whether oligomerization of the intracellular domain of the 55-kDa type 1 tumor necrosis factor (TNF) receptor may occur during TNF action. This assay depends upon reconstitution of the function of the GAL4 transcriptional activator through interaction of a protein fused to the GAL4 DNA binding domain with a protein fused to the transcriptional activation domain of GAL4. Fusion of the type 1 TNF receptor intracellular domain with the DNA binding domain and the transactivation domain of GAL4 led to activation of the lacZ indicator gene, demonstrating interaction of the receptor intracellular domain with itself. A HeLa cell cDNA library was searched for proteins that interact with the intracellular domain of the type 1 TNF receptor. A protein corresponding to amino acids 329-426 in the type 1 TNF receptor intracellular domain was identified by this screen. The aggregation domain was further defined by testing the ability of deletion mutants of the type 1 TNF receptor intracellular region to interact with the complete intracellular domain. These experiments map the aggregation domain to a sequence of amino acids previously shown to be responsible for mediating TNF-induced cytotoxicity. These results suggest that aggregation of type 1 TNF receptor intracellular domains may be important in TNF signal transduction.

Cloning, Molecular↗

PubMed1994

SH2-containing phosphotyrosine phosphatase Syp is a target of p210bcr-abl tyrosine kinase.

The phosphorylation of proteins at tyrosine residues is critical in cellular signal transduction and neoplastic transformation. These mechanisms are regulated by the activities of both protein-tyrosine kinases and protein-tyrosine phosphatases. Recent studies have identified a novel protein-tyrosine phosphatase, termed Syp, that is widely expressed in various tissues. Syp encodes a cytoplasmic phosphatase that contains two Src homology 2 (SH2) domains. Since SH2 domains have been shown to target the association of signal-transducing molecules to activated tyrosine kinases, experiments were performed to determine whether Syp might form specific complexes with p210bcr-abl, a fusion protein believed to be involved in the pathogenesis of chronic myelogenous leukemia and, thus, possibly alter or mediate p210bcr-abl tyrosine kinase activity. We found that Syp was highly and constitutively tyrosine phosphorylated in three different murine cell lines transfected with a p210bcr-abl expression vector. Furthermore, p210bcr-abl, Syp, and Grb2 formed stable complexes in BCR-ABL-expressing cells. Complex formation between p210bcr-abl and Syp was mediated in vitro by the NH2-terminal SH2 domain of Syp. Last, p210bcr-abl tyrosine kinase was effectively dephosphorylated by Syp in vitro. These results suggest an interaction between Syp and BCR-ABL protein, which might play a role in cellular transformation of BCR-ABL.

Animals↗

PubMed1994

Crystallization and characterization of colicin E1 channel-forming polypeptides.

Crystals of the channel-forming domain of colicin E1 from E. coli were grown by vapor diffusion at pH 6.4 and higher pH values. Cleavage of the colicin molecule with trypsin or thermolysin produced two of the pore-forming polypeptides used in these experiments. The third polypeptide was purified from a constructed plasmid that overexpresses only the C-terminal domain of colicin E1. Polypeptide crystals are tetragonal with space group I4, have one monomer in the asymmetric unit, and diffract to 2.2-2.4 A. Unit cell parameters for the tryptic and thermolytic polypeptides are a = 102.9 A and c = 35.6 A. Crystals of the overexpressed polypeptide have unit cell parameters of a = 87.2 A and c = 59.1 A. The crystals were characterized by precession photography, and native data sets of each channel-forming fragment were collected on a Siemens-Nicolet area detector. The crystallization and characterization of these polypeptides are the first steps in the structure determination of the channel-forming domain of colicin E1.

Amino Acid Sequence↗

PubMed1994

Nasolacrimal duct obstruction treated nonsurgically with use of plastic stents.

PURPOSE: To evaluate the clinical utility of plastic stents in treatment of complete obstruction of the nasolacrimal duct. MATERIALS AND METHODS: Nineteen plastic stents were successfully placed under fluoroscopic guidance in 16 consecutive patients with epiphora due to complete obstruction of the nasolacrimal duct. After balloon dilation of the obstructed area, the stents were placed in the lacrimal system with the head portion lying in the dilated lacrimal sac and the body in the nasolacrimal duct and projecting into the inferior meatus of the nasal cavity. RESULTS: Complete resolution of epiphora was accomplished in 15 (79%) of 19 eyes and partial resolution in the remaining four (21%) eyes. CONCLUSION: These preliminary results with use of plastic nasolacrimal stents are encouraging.

Adolescent↗

PubMed1994

Balloon dacryocystoplasty: results in the treatment of complete and partial obstructions of the nasolacrimal system.

PURPOSE: To evaluate the effectiveness of balloon dacryocystoplasty (DCP) in the treatment of complete and partial obstruction of the nasolacrimal system (NLS). MATERIALS AND METHODS: Fluoroscopically guided balloon DCP was attempted in 57 eyes of 50 consecutive patients with complete obstruction of the NLS and 24 eyes of 22 patients with partial obstruction of the NLS. With nasal endoscopic guidance, a 0.018-inch guide wire was introduced through the superior punctum into the inferior meatus of the nasal cavity and pulled out through the nare with a hemostat. A deflated angioplasty balloon catheter was introduced in a retrograde direction over the guide wire, and the balloon was dilated. RESULTS: Initial technical and clinical success was achieved in 29 of 57 eyes (51%) with complete obstruction and 17 of 24 eyes (71%) with partial obstruction. The 2-year cumulative clinical patency rates were 25% and 20% for partial and complete obstructions, respectively. The overall cumulative patency rate for all 81 eyes was 23%. CONCLUSION: Balloon DCP is simple and safe but has high failure and recurrence rates.

Adolescent↗