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Biomedical subjects

C J Wu

Publications and source records attributed to C J Wu.

At least 73 records · Page 4Linked to original sources
PubMed1997

Alterations of DNA methylation by glutathione depletion.

One of the most consistent findings in cancer cells is an overall decrease of 5-methylcytosine content in DNA. The causes that lead to this alteration are not known. We have shown in a recent study that the methyl-donor, methionine (Met), can easily be depleted and that O- and S-methylation can be impaired in response to glutathione (GSH) depletion. This is because mammalian cells are capable of resynthesizing GSH after GSH is depleted, and GSH turnover occurs at the expense of Met. An extensive utilization of Met for the resynthesis of GSH causes Met depletion and impairment in methylation. In the present study we now demonstrate that GSH depletion has a significant impact on DNA methylation. An i.p. dose of a model GSH-depleting hepatotoxin, bromobenzene (BB), caused a progressive impairment in genomic DNA methylation in the Syrian hamster. The administration of a single i.p. dose of Met labeled with [14CH3]Met to BB-treated hamsters at either 1, 3, 5.5 or 9 h after BB resulted in an increase of methyl-group incorporation into liver genomic DNA at 24 h after BB. With respect to the time points chosen for Met administration, methyl-group incorporation found in the BB + Met groups were 1-, 2-, 4- and 12-fold of the controls that received only Met. We further employed an in vitro methylation assay using specific bacterial SssI CpG methylase as the catalyzing enzyme to demonstrate that BB caused a progressive increase of unmethylated CpG sites in genomic DNA. Interestingly, the time response curve of global DNA methylation in vitro showed an identical pattern to that observed in the in vivo experiment. The results provide strong evidence that GSH-depleting agents significantly impair cytosine methylation. Thus, alterations in gene expression could result from a high dose and/or prolonged exposure to GSH-depleting agents, e.g. medications, chemotherapeutic agents and environmental toxins.

Animals↗
PubMed1997

Transradial coronary angiography and angioplasty in Chinese patients.

Radial artery punctures for diagnostic coronary angiography or coronary balloon angioplasty were performed in 211 patients with a success rate of 98% (207 patients). In the four failed transradial accesses, the procedure was accomplished via the transfemoral route. Major local vascular complications included one arteriovenous fistula, one pseudo-aneurysm, and one ischemic contracture of the right hand. Reduced radial pulses were noted in 25 (12%) patients at follow-up without ischemic manifestations. Transradial diagnostic coronary angiography was successfully completed in 184 (98%) of 187 patients. The technical success for balloon angioplasty was obtained in 73 (97%) of 75 patients. Clinical success was observed in 68 (91%) patients; balloon angioplasty resulted in one nonfatal myocardial infarction and four late deaths (3 cardiac and 1 stroke). We believe that transradial catheterization for diagnostic coronary angiography and balloon angioplasty in our relatively small built Chinese population is a safe and practical alternative approach.

Adult↗
PubMed1997

Sequence variations between two Epstein-Barr virus LMP 1 variants have no effect on the activation of NF-kappaB activity.

Previously, we reported that the LMP 1 gene of Epstein-Barr virus (EBV) derived from nasopharyngeal carcinoma (NPC) tissues (i.e., NLMP 1 gene) was able to transform BALB/c3T3 cells. On the other hand, LMP 1 gene of B95-8 strain (i.e., BLMP 1 gene) was not able to transform these cells (Chen et aL, 1992). Further studies indicated that a 10-amino-acid deletion in the carboxyl terminus of NLMP 1 played an important role in transformation (Li et al., 1996). In this study, we tested if this 10-amino-acid deletion affected the induction of NF-kappaB activity by LMP 1. The long terminal repeat of the human immunodeficiency virus type 1 (HIV-1 LTR) contained two copies of NF-kappaB sites and was used to construct the Luc gene-based reporter plasmid, p kappaB-Luc. Plasmid p kappaB-Luc was co-transfected with plasmids containing the NLMP 1 gene, BLMP 1 gene, and their chimeric or deletion constructs, respectively, into C-33A and BALB/c3T3 cells. The activation was then measured by the luciferase activity. Results showed that the full-length proteins induced a similar level of NF-kappaB activity, the two 3' mutants (R15delta and D4delta) still induced a relatively high level of activity, and the two 5' deletion mutants (delta3058 and delta3243) of NLMP 1 gene did not show any significant activation in C-33A cells. However, none of these LMP 1 proteins induced NF-kappaB activity in BALB/c3T3 cells. Using subcellular fractionation analysis and an immunocytostaining method, the truncated proteins of delta3058 and delta3243 were detected in the cytoplasm of the cells whereas the full-length NLMP 1 protein was located at the cytoplasmic membrane. Stable BALB/c3T3 cell clones that expressed both truncated proteins were established and then their ability to induce tumors in nude mice was examined. Data showed that both truncated NLMP 1 proteins still maintained partial transformation activity. Our results suggested that there was no direct correlation between NF-kappaB activation and transformation activity of LMP 1 in BALB/c3T3 cell transformation and that the amino-terminal membrane-spanning domain was important for maintaining both functions of LMP 1.

3T3 Cells↗
PubMed1997

Multidrug-resistant gene expression in small-cell lung cancer.

The development of drug resistance can contribute to treatment failure in small-cell lung cancer (SCLC). In this report, we investigate p-glycoprotein-mediated multidrug resistance (MDR) in these patients. Tumor tissue was obtained prior to treatment and at relapse if possible, short-term culture was carried out, and these tumor cells were analyzed for MDR gene expression by slot blot and reverse transcriptase polymerase chain reaction (RT-PCR) and northern blot analysis. Three cell lines were also established from short-term cultures. Twenty-four patients with MDR(-) and seven with MDR +(++) were available for survival analysis. Median survival for MDR (-) patients was 10 months, whereas for MDR +(++) patients it was 2 months. This was statistically significance (p < 0.0007). The presence of MDR1 gene expression also correlated with the lack of response to chemotherapy (p < 0.001). Increased MDR1 gene expression is usually present in patients with more tumor burden at initial diagnosis. Furthermore, loss of MDR1 gene expression can occur in intrinsically MDR(+) SCLC cells after multiple passages in drug-free media. We concluded that increased MDR1 gene expression is present in a small number of SCLC both before and after chemotherapy and usually signifies poor survival and no response to chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Expression of a streptomycete leaderless mRNA encoding chloramphenicol acetyltransferase in Escherichia coli.

The chloramphenicol acetyltransferase (cat) gene from Streptomyces acrimycini encodes a leaderless mRNA. Expression of the cat coding sequence as a leaderless mRNA from a modified lac promoter resulted in chloramphenicol resistance in Escherichia coli. Transcript mapping with nuclease S1 confirmed that the 5' end of the cat message initiated at the A of the AUG translational start codon. Site-directed mutagenesis of the lac promoter or the cat start codon abolished chloramphenicol resistance, indicating that E. coli initiated translation at the 5' terminal AUG of the cat leaderless mRNA. Addition of 5'-AUGC-3' to the 5' end of the cat mRNA resulted in translation occurring also from the reading frame defined by the added AUG triplet, suggesting that a 5'-terminal start codon is an important recognition feature for initiation and establishing reading frame during translation of leaderless mRNA. Addition of an untranslated leader and Shine-Dalgarno sequence to the cat coding sequence increased cat expression in a cat:lacZ fusion; however, the level of expression was significantly lower than when a fragment of the bacteriophage lambda cI gene, also encoding a leaderless mRNA, was fused to lacZ. These results indicate that in the absence of an untranslated leader and Shine-Dalgarno sequence, the streptomycete cat mRNA is translated by E. coli; however, the cat translation signals, or other features of the cat mRNA, provide for only a low level of expression in E. coli.

Chloramphenicol↗
PubMed1997

[Screening new photosensitizers from Chinese medicinal herbs and searching for herbal photodynamic killing effects on human stomach cancer cells].

OBJECTIVE: To find new photosensitizers from Chinese medicinal herbs for cancer photodynamic therapy. METHODS: The extracts of thirteen herbs were examined: (1) Their fluorescence excitation wave lengths and emission wave lengths; (2) Their fluorescence intensity in living cells and (3) Their distribution and localization in the living cells and the fixed cells both stained in each extract, and responses of cell fluorescence intensity to pH value change. Furthermore, the herb's anticancer photosensitive efficiencies were studied by using BCG-823 human stomach cancer cells. RESULTS: Cortex phellodendri and Rhizoma Coptidis, were found with optimal fluorescence properties as photosensitizers in this test. The latter could remarkably reduce the cell metabolic viability, proliferative ability and increased the cell mortality when the cells exposed to both drugs and luminance but not only to drug. CONCLUSIONS: The potential of Chinese medicine as new kind of photosensitizer and its possibility for use in anticancer photodynamic therapy are existed.

Drug Screening Assays, Antitumor↗
PubMed1997

Transfer of the E6 and E7 genes of human papillomavirus type 18 into human epithelial cells via recombinant retrovirus infection.

A retroviral vector carrying the E6 and E7 genes of HPV type 18 was transfected into a packaging cell line, Ampho psi 2. Thirteen recombinant viruses carrying the E6 and E7 genes were obtained. The titers of these recombinant viruses were estimated by infecting BALB/c3T3 cells and then counting the number of G418r colonies. Presence of HPV E6/E7 genes was confirmed by the PCR method and sequence-specific primers. The expression of E7 gene was examined by RT-PCR method. Results showed that the titers were ranged between 0.2 and 1.2 x 10(3) CFU/ml and the E7 transcripts were detected in all 13 cell clones. These E6 and E7-containing cell clones were able to grow in soft agar, indicating the E6/E7 delivered by the recombinant retroviruses retained their transformation function. These recombinant viruses were then used to infect human NPC cell lines, NPC-TW076 and -TW039 and cell clones resistant to G418 were obtained. Using Western blot analysis and HPV type 18 E6-specific monoclonal antibody, HPV-CIP5, these cells were shown to contain a protein with a molecular mass of 18 kDa. Our data indicated that the HPV E6/E7-containing recombinant retroviruses were capable of infecting human cell lines. The potential of using these recombinant retroviruses to immortalize human primary epithelial cells was discussed.

3T3 Cells↗
PubMed1997

Percutaneous transluminal angioplasty of the right coronary artery having an anomalous origin: two cases report.

Percutaneous transluminal coronary angioplasty was performed on 2 patients, each having an anomalous origin of the right coronary artery with anterior-superior orientation. Each patient had experienced post-infarction angina after an inferior wall myocardial infarction without antecedent thrombolytic therapy. The procedures were successfully performed with appropriate selection and manipulation of the guiding catheter. Our findings indicate that the Amplatz left catheter is the guiding catheter of choice in catheterizing a right coronary artery of anomalous origin with anterior-superior orientation.

Aged↗
PubMed1996

Post-transcriptional regulation of H-ferritin gene expression in human monocytic THP-1 cells by protein kinase C.

The mRNA coding for H-ferritin was highly induced in human monocytic THP-1 cells following treatment with phorbol 12-myristate 13-acetate (PMA). The induction was detected at 3 h, reached maximal levels at 12 h, and was sustained for up to 48 h subsequent to PMA exposure. PMA-induced up-regulation of H-ferritin gene expression was also observed in other leukaemic cell lines, HL60 and U937, but not in non-leukaemic cell types, including human fibroblasts, endothelial cells and smooth muscle cells. The effect of PMA could be completely blocked by the protein kinase C inhibitor, H-7. Furthermore, treatment of THP-1 cells with bacterial phospholipase C also produced a marked increase in expression of H-ferritin mRNA, suggesting the activation of protein kinase C was responsible for the accumulation of mRNA. Nuclear run-off experiments demonstrated that PMA did not increase the transcriptional rate of the H-ferritin gene. In contrast, the half-life of the H-ferritin mRNA measured in the presence of actinomycin D was greatly prolonged in PMA-treated cells. The induction of H-ferritin mRNA by PMA required no protein synthesis. Conversely, treatment of THP-J cells with protein synthesis inhibitor, cycloheximide, resulted in a 4-5-fold increase in H-ferritin mRNA. The increase in the stability of the H-ferritin mRNA was also observed in cells treated with cycloheximide. Taken together, these results suggest that the stability of H-ferritin mRNA in THP-1 is subjected to regulation via a protein kinase C-mediated phosphorylation on existing putative protein factor(s).

Cell Differentiation↗
PubMed1996

Translation of vph mRNA in Streptomyces lividans and Escherichia coli after removal of the 5' untranslated leader.

The Streptomyces vinaceus viomycin phosphotransferase (vph) mRNA contains an untranslated leader with a conventional Shine-Dalgarno homology. The vph leader was removed by ligation of the vph coding sequence to the transcriptional start site of a Streptomyces or an Escherichia coli promoter, such that transcription would initiate at the first position of the vph start codon. Analysis of mRNA demonstrated that transcription initiated primarily at the A of the vph AUG translational start codon in both Streptomyces lividans and E. coli; cells expressing the unleadered vph mRNA were resistant to viomycin indicating that the Shine-Dalgarno sequence, or other features contained within the leader, was not necessary for vph translation. Addition of four nucleotides (5'-AUGC-3') onto the 5' end of the unleadered vph mRNA resulted in translation initiation from the vph start codon and the AUG triplet contained within the added sequence. Translational fusions of vph sequence to a Tn5 neo reporter gene indicated that the first 16 codons of vph coding sequence were sufficient to specify the translational start site and reading frame for expression of neomycin resistance in both E. coli and S. lividans.

Amino Acid Sequence↗
PubMed1996

Concurrent 5-fluorouracil, daily low-dose cisplatin, and radiotherapy in stage IIIB cervical cancer. A phase II prospective study.

Between June 1987 and May 1991, 30 patients with Stage IIIB cervical cancers were treated using synchronous radiotherapy, 5-fluorouracil (5-FU), and daily low-dose cisplatin. External radiotherapy (3,600-3,960 cGy) was given to the whole pelvis in 4 weeks. Two courses of intracavitary brachytherapy were given 2 weeks later. Parametrial boost was then given. Continuous infusion of 5-FU 750 mg/m2 was given for 5 days during the first and third week of pelvic irradiation. Cisplatin (6 mg/m2) was given 30 min before every irradiation in the second and fourth week. The complete response rate was 87%. The 3-year local control rate was 77%. The 3-year overall and disease-free survival rate was 66% and 56%, respectively. Distant metastases were the major causes of treatment failure. Toxicities were acceptable. Our preliminary results indicate that this synchronous combination treatment is feasible. Further follow-up is required to determine whether this regimen has a genuine favorable impact on survival and chronic toxicity.

Adenocarcinoma↗
PubMed1996

Inguinal hernia in children: US versus exploratory surgery and intraoperative contralateral laparoscopy.

PURPOSE: To analyze the value of ultrasound (US) in the preoperative recognition of clinically apparent and inapparent inguinal hernias (or patent processus vaginalis). MATERIALS AND METHODS: Two hundred sixty children (197 boys, 63 girls), in whom a clinical diagnosis of inguinal hernia (226 unilateral hernias, 34 bilateral hernias) had been made, underwent US examination with a 7.0-MHz linear-array transducer. The contralateral internal inguinal ring was evaluated by means of intraoperative laparoscopy in 141 patients. The 197 boys were grouped together by age (< 12 months, 12-24 months, 24-48 months, 48-72 months, and > 72 months). RESULTS: In the 260 patients who underwent inguinal herniorrhaphy, 246 hernias (95%) were correctly diagnosed at US based on criteria of an internal inguinal ring width greater than 4 mm in diameter or the presence of fluid or organs in the inguinal canal at rest or during straining. A total of 473 hernias were confirmed surgically and 459 (97%) hernias were correctly detected at US. A statistically significant difference in the mean width of the internal inguinal ring of the five age groups was found between patients at rest and during straining (P < .05) in US measurement of the 197 surgically proved cases in boys. CONCLUSION: US is a noninvasive, readily available, and highly accurate (95%) method for evaluating the presence of inguinal hernia in children at risk, especially when the clinical findings are equivocal or normal. US can provide an objective measure in determining the advisability of exploratory inguinal surgery in such cases.

Adolescent↗
PubMed1996

Usefulness of intracardiac echocardiography in complex transseptal catheterization during percutaneous transvenous mitral commissurotomy.

OBJECTIVE: To examine the utility of intracardiac echocardiography in guiding complex transseptal catheterization of patients undergoing percutaneous transvenous mitral commissurotomy. DESIGN: We assessed this procedure in high-risk patients in whom transseptal catheterization is technically complex and more demanding. MATERIAL AND METHODS: Fifteen patients with mitral stenosis were studied. Twelve patients had giant left atria (70 mm or more), two had atrial septal aneurysms, and one had severe kyphoscoliosis. A newly developed 8-F 10-MHz intracardiac transducer catheter was placed in the right atrium through an 8-F Mullins sheath inserted from the left femoral vein. Echocardiographic images were used to confirm the septal position of the Brockenbrough needle tip before septal punctures. RESULTS: Transseptal puncture was successful and uncomplicated in all 15 patients. Use of intracardiac echocardiography eliminated the need for atrial angiography. Before transseptal puncture, the needle tip was identified to be in contact with the atrial septum, as an echogenic point with its acoustic shadow and septal indentation. In addition, in the two patients with aneurysms, puncture of the thin-walled aneurysms was avoided. CONCLUSION: Intracardiac echocardiography facilitates safe complex transseptal catheterization in patients with mitral stenosis and giant left atria, atrial septal aneurysms, or severe kyphoscoliosis.

Cardiac Catheterization↗
PubMed1995

Human papillomavirus type 18 DNA in gestational trophoblastic tissues and choriocarcinomas.

The objectives of our study were to better understand carcinogenesis of gestational trophoblastic tumors and to investigate the possible presence of human papillomavirus types 16 and 18 DNA sequences in these tumors. Amplification-based DNA methodology was used on 11 hydatidiform moles, 5 invasive moles, 8 choriocarcinomas and 9 normal early placental tissues. Human papillomavirus type 16 DNA was not found in any of these tissues. Although human papillomavirus type 18 DNA was also not found in the 9 normal placentas and 5 invasive moles, it was present in 2 of the 11 (18%) hydatidiform moles and in 4 of the 8 (50%) choriocarcinomas.

Base Sequence↗
PubMed1995

Twice-per-day fractionated high versus continuous low dose rate intracavitary therapy in the radical treatment of cervical cancer: a nonrandomized comparison of treatment results.

PURPOSE: To compare the efficacy of two twice-per-day fractionated high dose rate (HDR) brachytherapies with a historical control group treated with low dose rate (LDR) brachytherapy for cervical cancer patients. METHODS AND MATERIALS: From 1985 to 1988, 92 patients with cancer of the cervic were treated by remote-controlled, HDR brachytherapy, six fractions of 7 Gy per fraction (42 Gy) at point A (HDR-6). Fifty-seven patients were treated with four fractions of 8 Gy per fraction (32 Gy) at point A (HDR-4). A twice-per-day program was used for all HDR patients by two split courses. As a historical control, treatment results of 259 patients treated with LDR brachytherapy (40 Gy in two split courses) were compared with those of the two HDR regimens. All patients received whole pelvic external irradiation, 36-45 Gy (mostly 40 Gy) before brachytherapy. RESULTS: Five-year local control rates were not significantly different for the three groups (HDR-6 = 82.0%, HDR-4 = 85.5%, and LDR = 89.5%, respectively). Five-year survival rates were also comparable (67.7%, 77.9%, and 74.1%, respectively). However, late complications were lower in HDR-4 than HDR-6 (11.0% vs. 25.6%). CONCLUSIONS: Both 5-year local control and survival rates were comparable among the three groups. However, HDR-4, which was more biologically equivalent to our LDR regimen, showed fewer complications compared to HDR-6. In addition, our twice-per-day schedule shortened the hospital stay.

Adult↗