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Biomedical subjects

C L Wu

Publications and source records attributed to C L Wu.

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

Allelic imbalance on chromosome 3p in oral dysplastic lesions: an early event in oral carcinogenesis.

We have demonstrated previously a loss of constitutional heterozygosity on the short arm of chromosome 3 in approximately 50% of oral squamous cell carcinomas. In the present study, we have investigated 30 oral dysplastic lesions (DLs), presenting clinically as either erythroplakias or leukoplakias with histopathological features of either severe epithelial dysplasia or carcinoma in situ, for LOH on chromosome 3p using 15 microsatellite markers. Thirteen of the 30 LDs (approximately 43%) showed allelic imbalance at one or more loci. The pattern of loss in these lesions defined three noncontiguous regions of interstitial deletions that overlap with those defined for oral squamous cell carcinomas. These data indicate that the alteration of tumor suppressor genes on chromosome 3p is probably an early event in oral carcinogenesis. Additionally, 7 of the 30 DLs showed microsatellite instability. However, the frequency of loci showing microsatellite instability per lesion was low.

Alleles↗
PubMed1996

Molecular characterization of a plasmid-borne (pTC82) chloramphenicol resistance determinant (cat-TC) from Lactobacillus reuteri G4.

Lactobacillus reuteri G4 contains a 7.0-kb plasmid (pTC82) encoding resistance to chloramphenicol (Cm). Determination of the nucleotide sequence of the genetic determinant (cat-TC) encoding resistance to Cm on pTC82 revealed an open reading frame for a 238-amino-acid Cm acetyltransferase (CAT) monomer. This structural cat gene, 714 bp in length, was highly related (ca. 95% nucleotide and ca. 81% amino acid identity) to the 648-bp cat gene from Staphylococcus aureus plasmid pC194. A total of 6 bp transversions and 4 bp deletions was observed along the whole DNA sequence of cat-TC compared to that of cat-pC194. To determine the activity of the putative cat-TC gene, recombinant plasmid pUC8217 containing the cat determinant from pTC82 was subjected to a maxicell analysis. The observed molecular mass of the synthesized protein, based on electrophoretic mobility, was in reasonable agreement with the 27.3 kDa predicted from the DNA sequence. This is the first reported nucleotide sequence of a Cm-resistance determinant from L. reuteri and also the first evidence of adding Lactobacillus to the list of versatile bacterial genera which naturally acquire the cat-pC194 gene in the microbial ecological system.

Amino Acid Sequence↗
PubMed1996

Expression of dominant-negative mutant DP-1 blocks cell cycle progression in G1.

Unregulated expression of the transcription factor E2F promotes the G1-to-S phase transition in cultured mammalian cells. However, there has been no direct evidence for an E2F requirement in this process. To demonstrate that E2F is obligatory for cell cycle progression, we attempted to inactivate E2F by overexpressing dominant-negative forms of one of its heterodimeric partners, DP-1. We dissected the functional domains of DP-1 and separated the region that facilitate heterodimer DNA binding from the E2F dimerization domain. Various DP-1 mutants were introduced into cells via transfection, and the cell cycle profile of the transfected cells was analyzed by flow cytometry. Expression of wild-type DP-1 or DP-1 mutants that bind to both DNA and E2F drove cells into S phase. In contrast, DP-1 mutants that retained E2F binding but lost DNA binding arrested cells in the G1 phase of the cell cycle. The DP-1 mutants that were unable to bind DNA resulted in transcriptionally inactive E2F complexes, suggesting that the G1 arrest is caused by formation of defective E2F heterodimers. Furthermore, the G1 arrest instigated by these DP-1 mutants could be rescued by coexpression of wild-type E2F or DP protein. These experiments define functional domains of DP and demonstrate a requirement for active E2F complexes in cell cycle progression.

Animals↗
PubMed1996

Nuclear localization of DP and E2F transcription factors by heterodimeric partners and retinoblastoma protein family members.

E2F is a family of transcription factors implicated in the regulation of genes required for progression through G1 and entry into the S phase. The transcriptionally active forms of E2F are heterodimers composed of one polypeptide encoded by the E2F gene family and one polypeptide encoded by the DP gene family. The transcriptional activity of E2F/DP heterodimers is influenced by association with the members of the retinoblastoma tumor suppressor protein family (pRb, p107, and p130). Here the intracellular distribution of E2F and DP proteins was investigated in transiently transfected Chinese hamster and human cells. In transfected cells, DP-1 did not accumulate in the nucleus unless it was coexpressed with the heterodimeric partners E2F-1, E2F-2, or E2F-3. Domain mapping experiments showed that regions of E2F-1 and DP-1 that are required for stable association of the two proteins were also required for nuclear localization of DP-1. Unlike E2F-1, -2, and -3, E2F-4 did not accumulate in the nucleus unless it was coexpressed with DP-2, p107 and p130, but not pRb, stimulated nuclear localization of E2F-4, either alone or in combination with DP-2. These results indicate that DP proteins preferentially associate with specific E2F partners, and suggest that the ability of specific E2F/DP heterodimers to localize in the nucleus contributes to the regulation of E2F activity.

Animals↗
PubMed1996

The use of fiberoptic endoscopy in anesthesia.

The fiberoptic bronchoscope has contributed greatly to the practice of anesthesiology over the past 30 years. It has become an indispensable tool in the approach to the difficult airway, as well as the placement and positioning of double-lumen tubes for thoracic surgery. The equipment, preparation, and methods for using the endoscope in anesthesia, are presented here.

Anesthesia↗
PubMed1996

Education, age, and the cumulative advantage in health.

The positive association between educational attainment and health is well established, but the way in which the education-based gap in health varies with age is not. Do the health advantages of high educational attainment and disadvantages of low educational attainment diverge or converge with age? The cumulative advantage perspective predicts a diverging SES gap in health with age, but past evidence does not allow us to accept or reject the hypothesis. We address this issue in two samples, cross-sectionally and over time, with three health measures. The first data set consists of a 1990 telephone interview of a national probability sample of U.S. households. There are 2,031 respondents, aged 18 to 90. The second is a national probability sample of U.S. households in which 2,436 respondents aged 20 to 64 were interviewed by telephone in 1979 and reinterviewed in 1980. We find that the gap in self-reported health, in physical functioning, and in physical well-being among people with high and low educational attainment increases with age. The health advantage of the well educated is larger in older age groups than in younger. Health advantages of high income and disadvantages of low income also diverge with age, but household income does not explain education's positive effect.

Activities of Daily Living↗
PubMed1996

[Methicillin-resistant Staphylococcus aureus: an alarming problem in Chang Gung Memorial Hospital].

Strains of methicillin-resistant Staphylococcus aureus (MRSA) have become increasingly common in the United States and in many other countries since 1975. The prevalence of MRSA colonization and infection has increased in acute-care and chronic-care facilities, outpatient clinics, and in the community. We reviewed the sensitivity test of antibiotics in Chang Gung Memorial Hospital system, and revealed a steady decrease in sensitivity to Cephalothin, Oxacillin and Clindamycin during the past 10 years. It is still sensitive to Vancomycin. However, the amount of Vancomycin prescribed in the hospital system has increased three-folds during the recent 4 years. The purpose of this article is to review the MRSA in this hospital and to describe measures used to control MRSA transmission.

Methicillin Resistance↗
PubMed1995

Marchantinquinone, isolated from Reboulia hemisphaerica, as inhibitor of lipid peroxidation and as free radical scavenger.

The antioxidant effect of marchantinquinone was studied using various models. Marchantinquinone inhibited Fe(2+)-induced lipid peroxidation in rat brain homogenate in a concentration-dependent manner with an IC50 15.3 +/- 2.9 microM. Marchantinquinone was less effective than alpha-tocopherol and BHT in reducing the stable free radical diphenyl-2-picrylhydrazyl (DPPH). The IC0.200 were 37.5 +/- 2.5, 9.2 +/- 1.6 and 14.5 +/- 2.5 microM, respectively. Marchantinquinone also scavenged peroxyl radical derived from 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) in aqueous system with a stoichiometric factor of 0.9 +/- 0.1. Furthermore, it prevented conjugated-diene formation and apolipoprotein B (apo B) oxidation of LDL. However, marchantinquinone did not chelate Fe2+ or possess superoxide anion and hydroxyl radical scavenging activity. It also did not scavenge 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN)-derived peroxyl radical in hexane. These results indicate that marchantinquinone may be an effective antioxidant and can protect rat brain homogenate and LDL against oxidation.

Animals↗
PubMed1995

Prevention of emesis after strabismus repair in children: a prospective, double-blinded, randomized comparison of droperidol versus ondansetron.

STUDY OBJECTIVE: To compare the effectiveness of ondansetron with droperidol in preventing postoperative emesis in children after strabismus repair. DESIGN: Randomized, double-blind study. PATIENTS AND SETTING: 57 ASA physical status I and II children aged 3 to 14 years, undergoing outpatient strabismus repair in two separate study centers. INTERVENTIONS: Patients were randomized to receive either 0.15 mg/kg intravenous (i.v.) ondansetron or 0.075 mg/kg i.v. droperidol shortly after induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Number of episodes of emesis and times to discharge from the recovery room and ambulatory center were assessed. Twenty-nine (94%) of 31 children who received ondansetron and 21 (81%) of 26 children who received droperidol were emesis-free (p = NS). There were no significant differences in the number of episodes of emesis on the day after surgery or times to discharge. CONCLUSIONS: Ondansetron is at least as effective as droperidol in reducing the frequency of emesis in children after strabismus repair, and it did not shorten times to discharge home. The low number of patients in our study may have masked a difference in effect between the two groups. The clinician should decide whether the increased cost of ondansetron justifies its use over other antiemetics.

Adolescent↗
PubMed1995

In vivo association of E2F and DP family proteins.

The mammalian transcription factor E2F plays an important role in regulating the expression of genes that are required for passage through the cell cycle. This transcriptional activity is inhibited by association with the retinoblastoma tumor suppressor protein (pRB) or its relatives p107 and p103. The first cDNA from the E2F family to be cloned was designated E2F-1, and multiple E2F family members have now been identified. They bind to DNA as heterodimers, interacting with proteins known as DP. Here we demonstrate that DP is also a family of polypeptides with at least two members (hDP-1 and hDP-2). Both hDP-1 and hDP-2 bind to all E2F family members in vivo, and each complex is capable of activating transcription. However, the various E2F/DP complexes display strong differences in the ability to bind to either pRB or p107 in vivo, and the specificity of pRB or p107 binding is mediated by the E2F subunit.

Amino Acid Sequence↗
PubMed1995

Stiff-man syndrome: report of a case.

A 40-year-old Taiwanese farmer developed progressive stiffness and pain in the lower back with intermittent cramps over a 3-year period. The cramps were extremely painful and the patient was sensitive to any sudden movement or external stimulation. His lower back was so stiff that the patient had great difficulty performing daily activities and walked with a rigid and straight back. The stiffness of the muscles subsided during normal sleep. Except for a left S1 radiculopathy, no other neurologic abnormalities were noted. Electromyography showed spontaneous continuous muscle fiber activity which was markedly suppressed after a trial with 20 mg intravenous diazepam. The muscular stiffness disappeared during treatment with oral diazepam 80 mg daily, which was tapered to 15 mg daily without any recurrence of spasm for 20 months. This is the first report of stiff-man syndrome in a Taiwanese patient and emphasizes the importance of recognizing this treatable disease.

Adult↗
PubMed1994

Deletion mapping on the short arm of chromosome 3 in squamous cell carcinoma of the oral cavity.

Loss of heterozygosity indicative of the presence of tumor suppressor genes on chromosome 3p is commonly observed in carcinomas of various tissues. We have examined loss of heterozygosity on chromosome 3p in 27 oral squamous cell carcinomas using 15 highly informative microsatellite polymorphisms and constructed a deletion map of chromosome 3p. Overall, loss of heterozygosity at one or more loci was observed in 14 tumors (approximately 52%). A majority of these tumors (86%) show loss in more than one area. Three distinct regions were identified: 3p13-3p21.1, 3p21.3-3p23, and 3p25. These data suggest a role for at least three tumor suppressor genes on chromosome 3p in oral squamous carcinomas. The regions of deletions overlap with those described for carcinomas of other tissues and parallel those observed in lung carcinomas. This may reflect the common etiology of the two cancers.

Carcinoma, Squamous Cell↗
PubMed1994

Comparison of techniques for measurement of gelatinases/type IV collagenases: enzyme-linked immunoassays versus substrate degradation assays.

Radiolabeled substrate degradation assays and gelatin zymography are routinely employed to assay 72 kDa gelatinase A (MMP-2) and 92 kDa gelatinase B (MMP-9) in biological fluids. Enzyme-linked immunosorbent assays (ELISA) have recently been developed for the quantitation of these matrix metalloproteinases (MMP). In this study, we have compared ELISA to standard substrate degradation assays for measurement of MMP-2 and MMP-9 in human plasma and tumor-conditioned media. Gelatin Sepharose chromatography and gel filtration chromatography were employed as partial purification procedures for MMP-2 and MMP-9. The ELISA data for MMP-2 and MMP-9 are linear on a log:log regression curve over a wide range of MMP concentrations and are specific for the designated gelatinase, with no overlap detected with related metalloproteinases. The minimum detectable concentrations of MMP-2 and MMP-9 were approximately 0.5 ng/ml and 0.2 ng/ml, respectively, in the ELISA as compared to 4 ng/ml and 3 ng/ml, respectively, in gelatin zymography. The [3H]gelatin degradation assay required a combination of > 50 ng/ml of MMP-2 and MMP-9 for detection. Although gelatin zymography was less sensitive than ELISA (primarily due to the smaller sample volume employed) and was more difficult to quantitate, this procedure offers the important advantage of being able to distinguish between latent and activated gelatinases.

Collagenases↗
PubMed1994

Ondansetron decreases emesis after tonsillectomy in children.

We performed a double-blind, randomized, placebo-controlled trial to investigate the efficacy and safety of ondansetron in preventing vomiting after tonsillectomy with or without adenoidectomy in children. Sixty children were premedicated with 0.5 mg/kg of oral midazolam and underwent inhaled induction and maintenance of anesthesia with halothane and nitrous oxide. Intravenous morphine 0.075 mg/kg, vecuronium 0.1 mg/kg, and either ondansetron 0.15 mg/kg (maximum = 8 mg), or saline placebo were administered after intravenous catheter placement. All episodes of postoperative vomiting on the day of surgery and the following day were recorded. There were no significant differences between the two groups with regard to age, weight, sex, time to endotracheal intubation, duration of surgery, duration of anesthesia, or number of patients having adenoidectomy. More patients in the ondansetron group received dexamethasone as part of the surgeon's routine protocol (P = 0.03). Twenty-three children (77%) who received ondansetron were emesis-free as opposed to only eight (27%) in the placebo group (P < 0.001). This was especially evident in the number of children who had two or more episodes of vomiting; 17 children (57%) who received placebo had two or more episodes of vomiting as opposed to only two children (7%) who received ondansetron. The incidence of emesis on the day after the surgery did not differ between the two groups. Three children who received ondansetron and one who received placebo complained of abdominal cramping on the night of the surgery. There were no other complaints or complications. Analysis of the 51 children who did not receive dexamethasone revealed similar results.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1994

Gastric volume and pH in infants fed clear liquids and breast milk prior to surgery.

Recommendations for fasting intervals prior to anesthesia in pediatric patients have changed in recent years. There are few data concerning infants less than 1 yr of age fed clear liquids or breast milk before surgery. We performed a prospective, blinded study to determine residual gastric volumes and pH in this population. Approximately 2 h prior to surgery, 46 formula-fed infants ingested up to 8 oz of clear liquids and 24 breast-fed infants nursed as usual. After induction of general anesthesia and tracheal intubation, gastric fluid samples were aspirated by a blinded researcher who measured gastric volume and pH. Sufficient gastric fluid for analysis was obtained from 10 (22%) of the infants fed clear liquids and 8 (33%) of the breast-fed infants. For the group fed clear liquids, the residual gastric volume was 0.3 +/- 0.9 mL/kg and the pH was 2.1 +/- 1.4. Eight (17%) had gastric volumes > or = 0.4 mL/kg, 2 (4%) had gastric volumes > or = 1 mL/kg, and 9 (90%) of 10 measured had pH < or = 2.5. In the breast-fed group the residual gastric volume was 0.71 +/- 1.1 mL/kg (P = not significant [NS]) and the pH was 2.6 +/- 1 (P = NS). All eight (33%) breast-fed infants had gastric volumes > or = 0.4 mL/kg (P = NS), seven (29%) had gastric volumes > or = 1 mL/kg (P = 0.03), and four (50%) of eight measured had pH < or = 2.5 (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗