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Biomedical subjects

T Y Chen

Publications and source records attributed to T Y Chen.

At least 91 records · Page 5Linked to original sources
PubMed1996

Variations of the left and middle hepatic veins: application in living related hepatic transplantation.

The anatomic variations of the middle hepatic vein (MHV) and left hepatic vein (LHV) in 200 patients with normal liver function were analyzed using ultrasonography to clarify the feasibility of resecting the left lobe or left lateral segment in living subjects for living related hepatic transplantation (LRHT). The MHV and LHV form a common trunk in 70% of cases but drain independently into the inferior vena cava (IVC) in 30%. In 7% of cases, the left median vein (LMV) drains into the MHV, in 32% of cases the anterior superior segmental vein (ASSV) that drains segment 8 flows into the MHV. The distance between the two confluence points (LHV flows into MHV or IVC and LMV flows into the MHV) ranged from 0.3 cm to 2.5 cm with an average of 0.75 cm. The diameter of the LMV at the point that flows into MHV ranged from 0.3 cm to 0.9 cm. with an average of 0.61 cm. The distance from the IVC to the confluence of the MHV and LHV ranged from 0 cm to 3.5 cm with an average of 1.5 cm in those cases whose MHV and LHV presented as common trunks. Preoperative delineation of this complex venous anatomy is of paramount importance because the hepatic veins have to be transected in the cutting plane of the liver. The location of this plane is determined by the optimal graft volume required, and both the graft and the remnant liver have to retain perfect function. The venous anatomy would change the cutting plane in the living donor and the surgical method of anastomosis for the recipient.

Adult↗
PubMed1996

Photoelastic stress analysis of mandibular posterior cantilevered pontic.

The quasi-3D technique of photoelastic stress analysis was used to evaluate the stresses of mandibular posterior cantilevers for distal terminal abutments at various levels of periodontal support. The stress concentration index was selected to compare each model. The periodontal support of terminal abutment and the length of pontic must be considered, when a cantilever fixed partial denture is anticipated.

Alveolar Process↗
PubMed1996

Nonequilibrium gating and voltage dependence of the ClC-0 Cl- channel.

The gating of ClC-0, the voltage-dependent Cl- channel from Torpedo electric organ, is strongly influenced by Cl- ions in the external solution. Raising external Cl- over the range 1-600 mM favors the fast-gating open state and disfavors the slow-gating inactivated state. Analysis of purified single ClC-0 channels reconstituted into planar lipid bilayers was used to identify the role of Cl- ions in the channel's fast voltage-dependent gating process. External, but not internal, Cl- had a major effect on the channel's opening rate constant. The closing rate was more sensitive to internal Cl- than to external Cl-. Both opening and closing rates varied with voltage. A model was derived that postulates (a) that in the channel's closed state, Cl- is accessible to a site located at the outer end of the conduction pore, where it binds in a voltage-independent fashion, (b) that this closed conformation can open, whether liganded by Cl- or not, in a weakly voltage-dependent fashion, (c) that the Cl(-)-liganded closed channel undergoes a conformational change to a different closed state, such that concomitant with this change, Cl- ion moves inward, conferring voltage-dependence to this step, and (d) that this new Cl(-)-liganded closed state opens with a very high rate. According to this picture, Cl- movement within the pre-open channel is the major source of voltage dependence, and charge movement intrinsic to the channel protein contributes very little to voltage-dependent gating of ClC-0. Moreover, since the Cl- activation site is probably located in the ion conduction pathway, the fast gating of ClC-0 is necessarily coupled to ion conduction, a nonequilibrium process.

Animals↗
PubMed1996

C1-C2 fracture-dislocations in children and adolescents.

OBJECTIVE: C1-C2 is the predominant level of cervical spine injuries in children and adolescents. Either a fracture of the dens or atlantoaxial dislocation (AAD) without fracture of the dens can occur. We present a number of cases to compare their clinical presentations and discuss the preferred method of treatment. MATERIAL AND METHODS: There were 12 cases of type II odontoid fracture and 10 cases of AAD without fracture over a 13-year period. There was a male predominance and traffic collisions were the major cause of injury. Two thirds of the dens fractures were in children over 13 years of age and seven out of ten dislocations without fracture were under 13 years of age. Eight patients with fractured dens suffered from spinal cord injuries but six of those with dislocations were neurologically intact. Two patients of fractured dens and one with AAD presented with chronic myelopathies because of undetected injuries. RESULTS: Three patients expired because of irreversible respiratory failure. Most of the fractured dens achieved bony union after 3 months of halo-vest immobilization but those patients with AAD without fracture usually needed a fusion procedure. Transoral decompression was performed in two cases of dens fracture malunion. All of the survivors of the dens fracture returned to normal or independent daily living. Six of the AAD patients returned to normal, one had a mild neural deficit, and one had persistent spastic quadriparesis. CONCLUSIONS: There is a higher incidence of atlantoaxial dislocation without fracture in children under 13 years of age and a higher incidence of dens fractures in those over 13 years of age. Those with fractures of the dens are more likely to present with evidence of neural injury while those with AAD are more likely to be neurologically intact; however, a correct diagnosis and proper management are mandatory to prevent chronic myelopathy. Halo-vest immobilization is sufficient for most fractures of the dens in children, with AAD usually requiring a fusion.

Adolescent↗
PubMed1996

Clinical characteristics of and response to combination chemotherapy and subsequent application of international prognostic index in non-Hodgkin's lymphoma--an experience from a medical center in Southern Taiwan.

A retrospective analysis was performed of 117 non-Hodgkin's lymphoma (NHL) patients (72 male and 45 female, mean age 55 years) treated at NCKUH between July 1988 and December 1993. Of the 115 patients who could be classified by Ann Arbor staging system, 26 patients (22.2%) were in stage 1; 23 (19.7%) in stage 2; 29 (24.8%) in stage 3; and 37 (31.6%) in stage 4. According to the International Working Formulation, three patients (2.6%) were low grade NHL, 90 (76.9%) were intermediate, and 8 (6.8%) were high grade NHL. Histologically, diffuse large cell NHL accounted for 52.1% of cases, followed by 16.2% of cases exhibiting diffuse mixed NHL. Immunophenotype analysis was available in 95 cases, which revealed 76 (80%) cases exhibiting B-cell origin, 17 (18%) cases exhibiting diffuse mixed NHL. Immunophenotype analysis was available in 95 cases, which revealed 76 (80%) cases exhibiting B-cell origin, 17 (18%) cases exhibiting T-cell origin and 2 (2%) cases were of null cell type. All patients underwent two groups of induction chemotherapy, either CHOP (Cyclophosphamide, Epirubicin, Oncovin, and Prednisolone), or "modified" COPBLAM (Cyclophosphamide, Epirubicin, Oncovin, and Prednisolone), or "modified" COPBLAM (Cyclophosphamide, Epirubicin, Oncovin, Vinblastine, Bleomycin, Procarbazine, and Prednisolone). Seventy-two cases treated through COPBLAM and 45 cases treated through CHOP were evaluated. The response rate (RR) to COPBLAM treatment was 72.2% and was 68.9% for the CHOP group (P = 0.51). The 5-year overall survival rate (OAS) was 44.1% for COPBLAM, versus 40% for CHOP (P = 0.15). The disease-free survival (DFS) was 72.6% at 63 months for COPBLAM and 58% at 51 months for CHOP (P = 0.16). Neither B cell nor T-cell lineages of NHL showed any statistical difference in RR (P = 0.53, DFS (P = 0.58) or OAS (P = 0.97) to the different treatments. Using multiple logistic analysis, two independent factors, high LDH and advanced stage, were found to adversely affect the rate of complete remission. The application of the International Prognostic Index to our patients needs modification, which suggests the necessity of more evaluation before it can accurately be applied to all international series of NHL.

Adult↗
PubMed1996

Induction therapy of newly diagnosed acute nonlymphocytic leukemia with idarubicin and cytosine arabinoside--the Taiwan experience.

From October 1993 to December 1994, 26 patients with newly diagnosed and untreated acute nonlymphocytic leukemia (ANLL) received induction chemotherapy with the 3 + 7 regimen, i.e., idarubicin (IDA) 12 mg/m2/d for 3 days any cytosine arabinoside (Ara-C) 100 mg/m2/d for 7 days. Complete remission (CR) was achieved in 80.8% of the whole group and in 66.7% (two of three) of the elderly subgroup (age > or = 60 years). Seventeen patients achieved a CR after only one course, whereas four needed two courses. Toxicity was tolerable. All of the patients experienced myelosuppression, and infection episodes were noted in all except one patients. Other toxicities included vomiting (62%, mostly mild to moderate, grade I/II), diarrhea (46%, mostly grade I), mucositis (65%, mostly grade I), and alopecia (100%). None presented with liver dysfunction or cardiotoxicity. Of the 21 complete responders, one refused further consolidation, 20 received either two additional courses of IDA/Ara-C or high-dose Ara-C as consolidation, and one died of infectious complications during consolidation. As of May 1995, nine had relapsed, and 11 (55%) continued in CR for 6 to 21 months (median, 14.5). All four patients who needed two courses of IDA/ Ara-C to achieve remission had relapsed, with either high-dose Ara-C or allogeneic bone marrow transplantation (BMT) as postremission therapy. We suggest that induction failure with one course of IDA/Ara-C is a poor prognostic factor in ANLL.

Adult↗
PubMed1996

SS-A/Ro antibodies in Chinese patients with systemic lupus erythematosus and Sjögren's syndrome.

Serum from 53 patients with systemic lupus erythematosus (SLE) and 23 patients with primary Sjögren's syndrome (SS) were studied for anti-52-kDa SS-A/Ro, anti-60-kDa SS-A/Ro, and anti-SS-B/La antibodies by immunoblotting and enzyme-linked immunosorbent assay (ELISA). By immunoblotting, anti-SS-A/Ro was detected in 16 (30%) patients with SLE and 17 (74%) patients with SS. Anti-SS-B/La was detected in 22 (41%) patients with SLE and 15 (65%) patients with SS. Serum from 14 of the 16 SLE patients with anti-SS-A/Ro reacted with the 60-kDa protein and 15 serum samples from these patients recognized the 52-kDa protein. Serum with anti-60-kDa SS-A/Ro alone was not found. Serum from all of the 17 SS patients with anti-SS-A/Ro reacted with the 52-kDa protein, whereas serum from only two of these patients recognized the 60-kDa protein. By ELISA, the frequency of anti-SS-A/Ro (antibodies to the 60-kDa and/or 52-kDa of SS-A/Ro proteins) in patients with SLE and SS was 43/53 (81%) and 15/23 (65%), respectively. Anti-48-kDa SS-B/La was found in 28% and 48% of SLE and SS patients, respectively. Serum from 77% of SLE patients and 48% of SS patients reacted with the 60-kDa SS-A/Ro protein. Serum from 45% of SLE patients and 52% of SS patients reacted with the 52-kDa SS-A/Ro protein. Patients with SLE had significantly higher titers of antibodies to 60-kDa SS-A/Ro compared with patients with SS. Anti-SS-A/Ro and anti-SS-B/La are common in both SLE and SS. The different reactivities of anti-52-kDa and anti-60-kDa antibodies in serum from patients with SLE and SS may represent differences in conformation-dependent epitopes of SS-A/Ro autoantigens.

Adult↗
PubMed1996

[Post-obstructive pulmonary edema following extubation--report of two cases].

Pulmonary edema may develop in healthy patients after anesthesia. It usually results from upper airway obstruction which may be caused by laryngospasm or aspiration. Increased inspiratory effort following airway obstruction significantly produces negative intrathoracic pressure that may lead to pulmonary edema. We reported two cases of post-obstructive pulmonary edema following extubation. They were essentially healthy young males, one of whom received urethroplasty and the other received pulmonary blebectomy. Their hemodynamic and ventilatory conditions had been kept stable during surgery. Upper airway obstruction followed by pulmonary edema developed immediately after extubation, which was successfully treated without any sequelae.

Adult↗
PubMed1995

Structural and functional analysis of the human KB cell folate receptor gene P4 promoter: cooperation of three clustered Sp1-binding sites with initiator region for basal promoter activity.

The human folate receptors (hFRs) are important in the cellular accumulation of folates and antifolates. We described the structure of the human KB cell FR (hFR-KB) gene and identified two discrete promoter regions (P1 and P4) upstream from exons 1 and 4, respectively (Elwood et al., 1993). To further understand the molecular basis of hFR expression, we have now analyzed the basal transcription of the P4 promoter localized upstream of a major transcription start site. The sequence upstream from exon 4 contains several potential transcriptional factor-binding sites and a consensus initiator region sequence at the transcription start site but does not contain canonical TATA or CAAT boxes. While deletion of a 5' flanking sequence from nt -1023 to nt -605 of P4 promoter region decreases the luciferase reporter gene expression in KB cells to 54-70% of control construct, the removal of the sequence between nt -292 and nt -46 markedly decreases the activity to 3%. DNase I footprints and competitive mobility shift and supershift mobility assays indicate that Sp1 or Sp1-related nuclear protein(s) bind to three clustered GC-rich regions within the sequence between nt -292 and nt -46 of the hFR-KB P4 promoter. Both in vitro and in vivo analyses of the expression of promoter constructs containing site-specific mutation(s) of these three Sp1-binding sites and initiator sequence demonstrate that each of three Sp1 sites and the initiator sequence are required for optimum promoter activity and that they interact cooperatively in this P4 promoter of the hFR-KB gene.

Base Sequence↗
PubMed1995

Stress analysis of four-unit fixed bridges on abutment teeth with reduced periodontal support.

The variable properties of photoelastic models and the difficulty of fabrication of the model limit experimental designs. The 'material fringe value' is introduced into the definition of the 'stress concentration index' by multiplying the fringe orders. Three levels of periodontal support in three photoelastic models (nine cases) were compared quantitatively by determining the stress concentration induced in periodontium by point loading vertically on a span of the fixed partial denture of four units length. The results indicate that comparison among photoelastic models is possible and useful. The stress concentration effects produced by the second molar were more prominent and determinant than that by the first premolar in the periodontium of the abutments.

Alveolar Bone Loss↗
PubMed1995

Specificity of antinuclear antibodies in primary biliary cirrhosis.

OBJECTIVE: To study the specific autoantibodies against nuclear antigens in patients with primary biliary cirrhosis (PBC). METHODS: Sera from 21 patients with PBC were tested for antinuclear antibody (ANA) by indirect immunofluorescence on human epithelial (HEp)-2 cells, and for antibodies to various nuclear antigens by enzyme linked immunosorbent assay (ELISA) using different purified proteins or recombinant proteins as antigens. RESULTS: ANA detected in 10 of 21 patients (48%) with PBC included five anti-centromere antibody (ACA), two speckled, two homogeneous and one nuclear dot staining. ACA were present in 24% of PBC patients. By ELISA, anti-histone antibodies were detected in 81% of PBC patients, anti-ssDNA antibodies in 71% and anti-dsDNA in 10%, anti-topoisomerase-1 antibodies in 24%, anti-Sm/RNP antibodies in 24%, anti-La-48(SS-A) antibodies in 21%, and anti-Ro-60(SS-A) and anti-Ro-52(SS-A) antibodies in 30% and 25%, respectively. CONCLUSIONS: The high frequencies of various antibodies directed against intracellular proteins and nucleic acids in patients with PBC suggests that PBC is a multisystem autoimmune disease which is similar to other systemic autoimmune diseases.

Antibodies, Antinuclear↗
PubMed1995

Hepatocellular carcinoma with metastasis to right atrium--a report of three cases.

Hepatocellular carcinoma (HCC) is one of the most common neoplasma in Taiwan. The tumor itself has the tendency of extension into the venous system, such as to the portal vein, hepatic vein and inferior vena cava (IVC), but intra-atrial metastasis is unusual. Antemortem diagnosis was difficult before the availability of two-dimensional echocardiography (2-DE). Sometimes, the first symptoms and signs are cardiogenic manifestations such as dyspnea on exertion, syncope, edema of the lower legs, and shock. Clinicians may mistakenly make the wrong diagnosis of heart failure. Because of this, we hereby report three cases of HCC with right intra-atrial metastasis to raise the physician's awareness. All three cases initially presented as right side heart failure. Imaging study revealed hepatocellular carcinoma with right intra-atrial metastasis. Two of the three cases died within one month after diagnosis.

Aged↗
PubMed1995

Double pylorus: report of a longitudinal follow-up in two refractory cases with underlying diseases.

Double pylorus is either a congenital abnormality or an acquired complication of peptic ulcer disease. We had followed two patients for 3 and 5 yr, respectively, to observe the processes of formation and the prognosis of double pylorus. Initially, duodenal ulcer was found in one patient with diabetes mellitus and chronic renal failure, and gastric ulcer was found in the other with chronic obstructive pulmonary disease. Both developed double pylorus with refractory courses. In spite of intensive medical treatment, both of them had persistent ulcers in the fistulous tract and failed to develop reepithelization. Helicobacter pylori was found in all of the specimens of gastroduodenal biopsies in both cases. Therefore, we believe that the refractory courses of double pylorus may be related to the underlying diseases and/or the presence of H. pylori. Antibacterial treatment of H. pylori or surgical intervention should be considered for patients with this condition.

Aged↗
PubMed1994

Calcium-calmodulin modulation of the olfactory cyclic nucleotide-gated cation channel.

Although several ion channels have been reported to be directly modulated by calcium-calmodulin, they have not been conclusively shown to bind calmodulin, nor are the modulatory mechanisms understood. Study of the olfactory cyclic nucleotide-activated cation channel, which is modulated by calcium-calmodulin, indicates that calcium-calmodulin directly binds to a specific domain on the amino terminus of the channel. This binding reduces the effective affinity of the channel for cyclic nucleotides, apparently by acting on channel gating, which is tightly coupled to ligand binding. The data reveal a control mechanism that resembles those underlying the regulation of enzymes by calmodulin. The results also point to the amino-terminal part of the olfactory channel as an element for gating, which may have general significance in the operation of ion channels with similar overall structures.

Amino Acid Sequence↗
PubMed1994

Subunit 2 (or beta) of retinal rod cGMP-gated cation channel is a component of the 240-kDa channel-associated protein and mediates Ca(2+)-calmodulin modulation.

The cGMP-gated cation channel mediating visual transduction in retinal rods was recently found to comprise at least two subunits, 1 and 2 (or alpha and beta). SDS gels of the purified channel show, in addition to a 63-kDa protein band (subunit 1), a 240-kDa protein band that binds Ca(2+)-calmodulin, a modulator of the channel. To examine any connection between subunit 2 and the 240-kDa protein, cGMP-gated channels formed from the expressed cloned subunits in human embryonic kidney (HEK) 293 cells were tested for Ca(2+)-calmodulin effect. Homooligomeric channels formed by subunit 1 alone showed no sensitivity to Ca(2+)-calmodulin, and neither did heterooligomeric channels formed by subunit 1 and the short alternatively spliced form of subunit 2 (2a). By contrast, the cGMP half-activation constant (K1/2) for heterooligomeric channels formed from subunit 1 and the long form of subunit 2 (2b) was increased 1.5- to 2-fold by Ca(2+)-calmodulin, similar to the increase observed for the native channel. In Western blots of rod outer segment membranes, a subunit 2-specific antibody also recognized the 240-kDa protein. Finally, amino acid sequences derived from peptide fragments of the bovine 240-kDa protein showed approximately 80% identity to regions of subunit 2b of the human channel. These results together suggest that subunit 2b of the rod channel is a component of the 240-kDa protein and that it mediates the Ca(2+)-calmodulin modulation of the channel.

Amino Acid Sequence↗