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Biomedical subjects

Y Chao

Publications and source records attributed to Y Chao.

At least 109 records · Page 6Linked to original sources
PubMed2001

The clinical features and prognostic factors of hepatocellular carcinoma patients with spinal metastasis.

OBJECTIVE: Hepatocellular carcinoma is the most common malignancy in Taiwan, and spinal metastasis is a serious complication in cancer patients. In this study, we aimed to delineate the clinical features, evaluate the radiotherapy response and analyse the prognostic features in hepatocellular carcinoma subjects with spinal metastasis. METHODS: From 1981 to 1997, 102 patients with spinal metastasis were enrolled, taken from the 5887 documented hepatocellular carcinoma patients treated at Taipei Veterans General Hospital. All the clinical and laboratory data were recorded, including: age; gender; liver biochemistry; tumour characteristics; Child-Pugh's score; performance status; number and location of vertebral metastasis; motor capacity; neurological symptoms and signs; response to radiotherapy of the spinal lesion; and survival. Prognostic factors in hepatocellular carcinoma patients with spinal metastasis were analysed using Cox's regression model. RESULTS: The most common symptoms in hepatocellular carcinoma patients with spinal metastasis were lower back pain (74.5%), thoracic numbness (52.9%) and lower limb weakness (51.0%). Of the 102 patients, 84 received palliative radiotherapy using 3000 cGy for spinal lesions. Of these 84 patients, 32.1% showed a complete response, 26.2% a partial response and 41.7% a non-response to the radiotherapy. Multivariate Cox's regression analysis revealed that responsive radiotherapy (complete response + partial response) and good performance status (score <or= 2) were significant positive prognostic factors for survival in hepatocellular carcinoma patients with spinal metastasis. CONCLUSIONS: Responsive radiotherapy can improve a hepatocellular carcinoma patient's quality of life by ameliorating the neurological condition and relieving pain, and can prolong survival in hepatocellular carcinoma patients with spinal metastasis.

Adolescent↗
PubMed2001

Sugar coordinately and differentially regulates growth- and stress-related gene expression via a complex signal transduction network and multiple control mechanisms.

In plants, sugars are required to sustain growth and regulate gene expression. A large set of genes are either up- or down-regulated by sugars; however, whether there is a common mechanism and signal transduction pathway for differential and coordinated sugar regulation remain unclear. In the present study, the rice (Oryza sativa cv Tainan 5) cell culture was used as a model system to address this question. Sucrose and glucose both played dual functions in gene regulation as exemplified by the up-regulation of growth-related genes and down-regulation of stress-related genes. Sugar coordinately but differentially activated or repressed gene expression, and nuclear run-on transcription and mRNA half-life analyses revealed regulation of both the transcription rate and mRNA stability. Although coordinately regulated by sugars, these growth- and stress-related genes were up-regulated or down-regulated through hexokinase-dependent and/or hexokinase-independent pathways. We also found that the sugar signal transduction pathway may overlap the glycolytic pathway for gene repression. alpha-Amylase and the stress-related genes identified in this study were coordinately expressed under sugar starvation, suggesting a convergence of the nutritional and environmental stress signal transduction pathways. Together, our studies provide a new insight into the complex signal transduction network and mechanisms of sugar regulation of growth and stress-related genes in plants.

DNA, Complementary↗
PubMed2001

Phase II trial of systemic recombinant interleukin-2 in the treatment of refractory nasopharyngeal carcinoma.

BACKGROUND: Interleukin-2 (IL-2) is a cytokine produced by activated T cells, which has shown powerful immunostimulatory and antineoplastic properties. Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus-associated cancer with abundant lymphocyte infiltration histologically. The activity of IL-2 in the treatment of NPC patients is currently unknown. A phase II study was, therefore, initiated to evaluate the efficacy, toxicity and immunological consequences of intravenous bolus IL-2 in patients with recurrent/metastatic NPC. METHODS: Between November 1996 and April 1997, 14 patients with recurrent/metastatic NPC were entered into the study. Recombinant IL-2 (Proleukin, Chiron) was injected by intravenous bolus every 8 h at 72,000 IU/kg for a maximum of 15 doses. After 7 days, patients were retreated with a second identical cycle of therapy. Those patients who were stable or responding to treatment 5-6 weeks later went on to receive another course (two cycles) of therapy. All patients received prophylactic antibiotics and antipyretic medicine. Response and toxicities were evaluated. Serial plasma level of TNF-alpha, IL-6, soluble IL-2 receptor, IL-10 and soluble CD8 were determined. RESULTS: Fourteen patients received a total of 34 cycles of therapy. No response was observed. Fifty percent had stable disease, 50% had progressive disease after a median of two cycles of therapy. There was one treatment-related death from acute myocardial infarction. Body weight increase (>5%) occurred in 80% of cycles, and hypotension (BP <80 mm Hg systolic) occurred in 53%. Serum creatinine increase (>2 mg%) occurred in 24% of cycles, and SGOT/SGPT increase (>3x) in 10% of cycles. Symptoms of somnolence, general malaise, nausea and vomiting, pruritus, xerostomia, desquamation were generally mild to moderate but rapidly reversible. CONCLUSION: The single modality of intravenous bolus IL-2 at the dose level of 72,000 IU/kg is clinically ineffective in NPC patients. Potential mechanisms of the ineffectiveness of IL-2 therapy on NPC patients are discussed.

Adult↗
PubMed2001

Preclinical evaluation of locoregional delivery of radiolabeled iododeoxyuridine and thymidylate synthase inhibitor in a hepatoma model.

UNLABELLED: We report improved incorporation of the radiolabeled-thymidine analog [125I/131I]5-iodo-2'-deoxyuridine ([125I/131I]IdUrd) into DNA by the addition of Thymitaq, a thymidylate synthase inhibitor, as a strategy of molecular radiotherapy for hepatoma treatment. METHODS: The synergistic effect of combination [125I]IdUrd and Thymitaq in clonogenic survival and DNA incorporation was shown on the human hepatoma cell line Hep3B. Radiobiodistribution of intrahepatic arterially injected [125I]IdUrd and Thymitaq was studied in a rat N1S1 hepatoma model. In vivo therapeutic effects of locoregional delivery of both drugs were evaluated in mouse subcutaneous hepatoma and ascitic hepatoma models. RESULTS: In a clonogenic assay, Thymitaq showed a synergistic effect with [125I]IdUrd but not cold IdUrd. Thymitaq had a dose-dependent modulation effect on DNA-[125I]IdUrd incorporation. The biodistribution study indicated a slower clearance rate of [125I]IdUdR in the hepatoma as well as an initially higher uptake of [125I]IdUrd into DNA when the [125I]IdUrd was combined with Thymitaq. In vivo studies showed a superior therapeutic effect of combination Thymitaq and [125I]IdUrd in both subcutaneous and ascites tumor models, but the combination of [131I]IdUrd and [125I]IdUrd may be more effective than Auger electron emitters alone for the treatment of subcutaneous tumor. CONCLUSION: The strategy of locoregional delivery of [125I/131I]IdUrd to a tumor site through an intrahepatic arterial, intratumoral, or intraperitoneal route in combination with Thymitaq is promising and may also have a favorable therapeutic index in vivo.

Animals↗
PubMed2001

An unusual cutaneous metastasis from hepatocellular carcinoma.

Cutaneous metastases from hepatocellular carcinoma are rare. In this report we detail a case of hepatocellular carcinoma with the unusual manifestations of multiple skin metastases. A 49-year-old male, who had received surgical resection of hepatocellular carcinoma one year prior, presented with multiple reddish-blue, firm, painless and nonulcerative cutaneous papules and nodules over the fingers, palms, toes, soles and back. Pathology of the cutaneous nodules showed characteristic hepatocellular carcinoma with trabecular gland formation. These lesions grew very rapidly and developed to cauliflower appearances which had not been described previously in the literature. The patient died of respiratory failure secondary to lung metastasis two months after the first appearance of the skin lesions.

Carcinoma, Hepatocellular↗
PubMed2001

[Degradation of methamidophos by Saccharomyces rouxii WY-3].

A strain of Yeast WY-3 was isolated from wastewater sample. It is capable of utilizing methamidophos as sole nitrogen and phosphorus sources, and also capable of utilizing methylamine, ethylamine and ammonium sulfate as nitrogen sources except nitrate and hydroxylamine. The yeast could grow in medinm containing 60% glucose and was identified as Saccharomyces rouxii WY-3. The strain contains a high active acid phosphatase. The crude enzyme was applied to a plate of polyacrylanide gel for electrophoresis, then activity was detected as white single band. Inhibiting test showed that sodium fluoride could seriously inhibit the activity of acid phosphatase to release phosphorus from methamidophos, wherease it make no effect on deamination of the strain WY-3 from methamidophos. After methamidophos was degraded by strain WY-3, toxity of the pesiticide reduced obviously, and its portion intermediate, methanol and inorganic phosphorus, were deteted.

Biodegradation, Environmental↗
PubMed2001

[Determination of shrinkage and bending strength of GI-II infiltrated ceramic].

OBJECTIVE: To determine the shrinkage and strength of GI-II Infiltrated Ceramic for providing scientific basis of its clinical use. METHODS: The adobes by slip-casting alumina powder of GI-II Infiltrated Ceramic were sintered at 1125 degrees C for 2 hours. The sintered alumina bodies were then divided into two groups and infiltrated by melt glass at 1125 degrees C and 1100 degrees C respectively for 6 hours. The length of the infiltrated ceramic specimens before and after fabrication was determined to calculate shrinkage. Their strength values were obtained by 3-point bending test. RESULTS: The infiltrated ceramic infiltrated at 1125 degrees C was 0.289 +/- 0.155% in shrinkage, 367.7 +/- 76.1 MPa in strength, and 4.79 in Weibull modulus; that infiltrated at 1100 degrees C was 0.253 +/- 0.043%, 377.5 +/- 64.4 MPa, and 5.52, respectively. There was no statistically significant difference between those two groups. But their strength values were statistically high, compared with 300 MPa. CONCLUSION: The shrinkage of GI-II Infiltrated Ceramic could be compensated by brushing spacer on dies and expansion of die stone. Its strength satisfied the requirement for clinical use of all-ceramic bridge materials. This kind of high-strength and low-shrinkage ceramic could be used for fabricating all ceramic crown and bridge core.

Aluminum Oxide↗
PubMed2001

[Shear bond strengths of four types of adhesive resin agents to GI II glass infiltrated ceramic].

OBJECTIVE: The shear bond strength of four adhesive resins bonded to GI II glass infiltrated alumina ceramic was investigated in this experiment. METHODS: A total of 40 ceramic blocks and 40 tooth blocks were prepared and divided into 4 experimental groups, including group A (CereDual and silicoating), group B (Calibra and silicoating), group C (Panavia) and group D (Super C&B and silicoating). The shear strength of four different bonding systems to dentin was tested respectively. The data were statistically analyzed. RESULTS: More than 13 MPa of bonding strength was achieved using the traditional Bis GMA bonding resin (groups A and B), and more than 16 MPa was obtained using the improved Bis GMA bonding resin (group C and D). There was statistical difference between groups A, B and group C, D. CONCLUSION: It can be implied that an ideal bonding can be obtained by using different bonding materials and processing the dentin surface with the suitable conditioner.

Dental Bonding↗
PubMed2001

[Shear strength of bond of the dentin to GI-II glass-infiltrated alumia ceramic agter varying modes of surface conditioning].

OBJECTIVE: The adequate surface conditioning method for GI-II glass infiltrated alumia ceramic was investigated. METHODS: The test specimens were divided into 3 groups (A. HF + silicon, B. sandblasting + silicone and C. thermal silicoating + silicone). Shear bonding strengths of porcelain bonded to dentin were tested. RESULTS: The bond strength of group A and B slightly increased after one day but decreased sharply after 30 days. However, no statistical significance was observed. The group C showed a pronounced enlargement of bond strength after one day and had a durable bond after 30 days' thermal cycling. It is statistically significant when group C was compared with group A and B. CONCLUSION: It can be inferred that silicoating method be a better way for glass infiltrated alumia ceramic bonding.

Aluminum Oxide↗
PubMed2001

[Biological assessment of sintered titanium alloy for dental crown and bridge by means of slip casting].

OBJECTIVE: To evaluate the biological safety of sintered titanium alloy for dental crown and bridge, and provide a sound scientific basis for dental clinical practice. METHODS: A series of tests, including acute toxicity test, cytotoxity test (agar overlay), sensitization test, oral mucous membrane irritation test, haemolysis test and micronucleus test were conducted to examine the dental crown/bridge-used titanium alloy which is processed with vacuum-sintered powder metallurgy. RESULTS: The haemolysis rate of this material was 2.21% (less than 5%), an index of good blood compatibility. Cytotoxic effect was not observed in cell culture, nor was toxic effect observed in mouse toxicity test. Local mucous membrane irritation reaction was not found. No potential mutagenicity of this material was noted. CONCLUSION: Dental crown/bridge-used titanium alloy material is of reliable was noted biological safety in dental clinical application.

Animals↗
PubMed2001

[Characterization of alumina adobe and sintered body of GI-infiltrated ceramic].

OBJECTIVE: This study was conducted to elucidate the mechanism of formation of porous structure by investigating the porosity of the alumina adobe and sintered body of GI-II Infiltrate Ceramic, and its role in strengthening and toughening this kind of ceramic composite. METHODS: The alumina powder size-mass distribution was obtained by BI-XDC powder size analysis device; the open pore parameters of alumina adobe and sintered body were analyzed using the mercury pressure method. Their fracture surfaces were observed under scanning electronic microscope. RESULTS: Fine powder had two main size groups of 0.09-0.1 micron and 0.2-0.5 micron, respectively, and coarse powder, with size between 1.5 to 4.5 microns, occupied the majority of powder mass. Alumina adobe's pores became larger after sintering. The median pore radii of adobe and sintered body were 0.2531 micron and 0.3081 micron, respectively; the average pore radii changed from 0.0956 micron to 0.1102 micron. Under scanning electronic microscope, fine alumina powders were fused partially together and their surfaces were blunted, but coarse powders did not show such phenomena. CONCLUSION: The alumina size distribution contributes to the formation of porous structure of alumina sintered body. This porous structure is not only the shape skeleton but also the mechanical skeleton of GI-II Infiltrated Ceramic. It plays an important role in raising the mechanical properties of this kind of ceramic composite.

Aluminum Oxide↗
PubMed2000

Selective production of L-aspartic acid and L-phenylalanine by coupling reactions of aspartase and aminotransferase in Escherichia coli.

With L-aspartate (L-Asp) as the amino donor, L-phenylalanine (L-Phe) can be prepared from phenylpyruvate (PPA) via an amination reaction mediated by aminotransferase (encoded by aspC). On the other hand, L-Asp can be produced by an aspartase (encoded by aspA) -catalyzed reaction using fumaric acid as substrate. To overproduce aspartase in Escherichia coli, the aspA gene was cloned and overexpressed 180 times over the wild-type level. The use of AspA-overproducing E. coli strain for L-Asp production exhibited an 83% conversion, approaching to the theoretical yield, whereas the wild-type strain obtained scarcely L-Asp. Furthermore, the recombinant strain overproducing both AspA and AspC was able to produce L-Asp and L-Phe simultaneously by using fumaric acid and PPA as substrates. As a result, the conversion yields obtained for L-Asp and L-Phe were 78% and 85%, respectively. In sharp contrast, the wild-type strain attained a conversion of L-Phe less than 15% and an undetectable level of L-Asp. This result illustrates a potential and attractive process to yield both L-Asp and L-Phe by coupling AspA and AspC. A further study on the repeated use of the recombinant strain immobilized with calcium alginate showed that after eight batch runs L-Asp conversion maintained roughly constant (around 75%), whereas L-Phe conversion dropped to 65% from 81%. This result indicates the stability of AspA being superior to AspC.

Journal Article↗
PubMed2000

Bacterial cellulose production by Acetobacter xylinum in a 50-L internal-loop airlift reactor.

Bacterial cellulose (BC) production was realized in a batch cultivation of Acetobacter xylinum subsp. sucrofermentans BPR2001 in a 50-L internal-loop airlift reactor. When the bacterium was cultivated with air supply, 3.8 g/L of BC was produced after 67 hours. When oxygen-enriched gas was supplied, the concentration of BC was doubled and the production rate of BC was 0.116 g/L. h, which was two times higher than that of air-supplied culture and comparable to that in a mechanically agitated stirred-tank fermentor. Bacterial cellulose produced by the airlift reactor formed a unique ellipse pellet (BC pellet), different from the fibrous form which was produced in an agitated stirred-tank fermentor. The BC-pellet suspension was demonstrated to have a higher volumetric oxygen transfer coefficient than the fibrous BC suspension in a 50-L internal-loop airlift reactor. The mixing time of BC-pellet suspension in the airlift reactor was also shorter than that in water.

Air↗
PubMed2000

Recombinant Escherichia coli cell for d-p-hydroxyphenylglycine production from d-N-carbamoyl-p-hydroxyphenylglycine.

Recombinant Escherichia coli cell containing D-amidohydrolase was employed to convert D-N-carbamoyl-p-hydroxyphenylglycine (D-CpHPG) to D-p-hydroxyphenylglycine (D-pHPG). Biotransformations under pH 7 and 40 degrees C allowed to complete conversion of D-CpHPG into D-pHPG. Under the same reaction pH, the D-amidohydrolase activity of the cell in the phosphate buffer was higher than that in the Tris buffer. The activity decreased with the increase of phosphate buffer concentration. Instead of using buffer, the reaction pH maintained constant at 7 by titrating with 1 N HCl resulted in a higher D-pHPG production rate. Flocculating the cell suspension with chitosan and cross-linked by glutaraldehyde made the cell recovery for repeated use much easier. Both the cross-linking and (PMSF; a protease inhibitor) treatments could increase the cell reusability and storage stability. However, the cross-linking decreased the D-amidohydrolase activity of the cell to about 50%. The D-amidohydrolase activities of free and cross-linked cell were inhibited at substrate concentration higher than 150 mM and 100 mM, respectively. The conversion of 150 mM D-CpHPG to D-pHPG could be completed within 7 h for the free cell at the concentration of 10% (wet weight/volume).

Journal Article↗
PubMed2000

Integration of computer-assembled digital images and text data as evidence for the oncological record.

Digitally created visual images of pertinent patient data have been integrated with text information to formulate a visual evaluation and summary sheet (VESS) using computer processing. The VESS incorporates images of a patient's physical appearance, radiological images, pharmacokinetic graphs, and text information into a 1-page document of the patient's condition. Thus, computer processing of digital images and other information helps to refine patient data presentation, analysis, interpretation, and communication. This form of data management is especially valuable in oncological research, where clinical trials demand rapid, ongoing assessment of results and analysis of large amounts of data. The VESS is an effective mechanism for monitoring both the progress of individual patients and the endpoints of the overall clinical trial.

Diagnostic Imaging↗
PubMed2000

Activation of MAD 2 checkprotein and persistence of cyclin B1/CDC 2 activity associate with paclitaxel-induced apoptosis in human nasopharyngeal carcinoma cells.

Paclitaxel (Taxol) is a microtubule-interfering agent that induced persistent and transient G2/M arrest before apoptosis in human nasopharyngeal carcinoma (NPC) cells at high and low concentrations, respectively. In this study, we intended to explore the underlying molecular events and found that cellular cyclin B1/CDC 2 kinase activity was increased and persisted for >6 h upon paclitaxel treatment both at high and low concentrations. Furthermore, activation of MAD 2 checkprotein could account for the loss of cyclin B1 ubiquitination and the persistence of cyclin B1/CDC 2 activation in the cases. To investigate the involvement of cyclin B1 and MAD 2 activation in paclitaxel-induced apoptosis, we introduced affinity-purified anti-cyclin B1 and MAD 2 antibodies into NPC cells by electroporation before the further paclitaxel treatment. The antibodies against cyclin B1 and MAD 2 indeed attenuated paclitaxel-induced cytotoxicity and DNA fragmentation. Our study suggests that activation of cyclin B1/CDC 2 and MAD 2 were the M-phase events required for paclitaxel-induced apoptosis in NPC cells. The dys-regulated cyclin B1/CDC 2 activation could enhance the prometaphase progression, but activation of MAD 2 rendered cells inable to exit from the metaphase. Under this circumstance, cells were probably going to "mitotic catastrophe" and ultimately, destined to apoptosis.

Antibodies↗
PubMed2000

Life-threatening haemorrhage from a sternal metastatic hepatocellular carcinoma.

Rupture of the tumour is a catastrophic complication of hepatocellular carcinoma. The prognosis in patients with a ruptured hepatocellular carcinoma is usually unfavourable. We describe a 46-year-old man who suffered from visible massive tumour haemorrhage due to a hepatitis B-related hepatocellular carcinoma that metastasized to the sternal bone. The prominent tumour mass was bulging over the anterior chest wall on the sternum of the patient, and bled spontaneously. This episode of life-threatening haemorrhage was stopped by surgical ligation of the bleeding site. Palliative radiotherapy shrank the tumour mass size and prevented further possible bleeding. This is likely to be the first reported case with a visible spontaneous tumour bleeding from a sternal metastatic hepatocellular carcinoma.

Bone Neoplasms↗