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Biomedical subjects

C C Chou

Publications and source records attributed to C C Chou.

At least 37 records · Page 2Linked to original sources
PubMed2001

Increased stability of nucleophosmin/B23 in anti-apoptotic effect of ras during serum deprivation.

We obtained evidence that increased stability of nucleophosmin/B23 is involved in antiapoptotic effect of ras during serum deprivation. Nucleophosmin/B23 in serum-deprived (0% serum) NIH-3T3 cells was found to be highly unstable with a half-life less than 4 h. In contrast, nucleophosmin/B23 in serum-deprived ras-transformed (RAS-3T3) cells was as stable as that in serum-supplemented NIH-3T3 or RAS-3T3 cells. Treatment of RAS-3T3 cells with nucleophosmin/B23 antisense oligomer significantly potentiated the apoptosis induced by serum deprivation. Much less caspase-3 activity was noted in the lysate derived from serum-deprived RAS-3T3 cells compared with that in the lysate of serum-deprived NIH-3T3 cells. Cell permeable caspase-3 inhibitor added in the medium blocked the decrease of nucleophosmin/B23 and apoptosis induced by serum deprivation in NIH-3T3 cells. The inhibitor, on the other hand, promoted significant decrease of nucleolin/C23 in NIH-3T3 cells during serum deprivation. Unlike nucleolin/C23, down-regulation of nucleophosmin/B23 was thus not proliferation-dependent but caspase-3- and apoptosis-dependent. Our results indicate important relationships among ras, nucleophosmin/B23, activation of caspase-3, and induction of apoptosis.

3T3 Cells↗
PubMed2001

Screening procedure from cattle feces and the prevalence of Escherichia coli O157:H7 in Taiwan dairy cattle.

A procedure has been established for screening Escherichia coli O157:H7 from bovine feces. It consists of four steps: enrichment, selective culture, phenotyping and genotyping. Modified trypticase soy broth (mTSB) containing 20 microg/mL of novobiocin was used for the enrichment step. The selective culture step was done using sorbitol MacConkey agar containing 0.05 microg/mL of cefixime and 2.5 microg/mL of potassium tellurite. The phenotyping steps include: species confirmation as E. coli, serotyping to O157 and H7, and the detection of verocytotoxin (VT) production. Genotyping was made up of confirmation of the presence of the O157 antigen (rfb), the H7 antigen (ficC), the adherence factor (eaeA), hemolysin (hlyA), and VT production (vt I and vt II) by polymerase chain reaction. mTSB gave better enrichment for E. coli O157 than gram-negative (GN) broth. The detection limit for this screening procedure was 0.85 +/- 0.5 cfu/g. Using the screening procedure described above, E. coli O157 was found in four out of 3062 (0.13%) fresh bovine fecal specimens, and in two out of 78 (2.56%) dairy herds in Taiwan. Three out of the four detected strains were vt II producing E. coli O157:H7, while the other was E. coli O157:H7 which lacked VT-producing ability.

Animals↗
PubMed2001

[The decision-making process of pregnant women with positive reaction to maternal serum screening for Down's syndrome when facing amniocentesis].

The purpose of this study was to explore the decision-making process of pregnant women with positive reaction to maternal serum screening for Down's syndrome when facing amniocentesis. Seventeen pregnant women consented to participation in this study. The data were collected through semi-structured interviews and analyzed using the grounded theory method. The findings revealed that there were four decision-making patterns. Each pattern could be grouped into three stages: post-acknowledgement transition, decision-making transition, and after-decision transition. Most participants had psychological reactions, which included shock, fear, nervousness, worry, sadness, and stress. Their concerns during the decision-making transition stage were: confirmation of health, normality, and safety of the fetus, fear of abortion due to amniocentesis, clarification of relations between amniocentesis and maternal serum screening, opinions from physicians and family members, and fear of artificial abortion for unhealthy fetus. Concerns during the after-decision transition stage were: information relating to amniocentesis, the management of an abnormal fetus, the place for amniocentesis, preparation before amniocentesis, and inadequate time for making a decision. Coping strategies were developed to deal with their concerns.

Adult↗
PubMed2001

Endoscopic variceal ligation for intractable esophageal variceal bleeding in children with idiopathic extrahepatic portal vein occlusion: report of three cases.

Extrahepatic portal vein occlusion (EPVO) is an important cause of extrahepatic portal hypertension and variceal hemorrhage in children. We report 3 children with a diagnosis of EPVO and intractable esophageal variceal bleeding who underwent scheduled endoscopic variceal ligation (EVL) and prophylactic propranolol therapy for eradication of esophageal varices. Complete variceal obliteration was achieved in all 3 children following 3-4 treatment sessions. There were no significant complications or gastrointestinal hemorrhage during a follow-up period of 9 to 31 months after variceal eradication. In conclusion, EVL and long-term propranolol prophylaxis is safe and effective in eradicating bleeding esophageal varices in children with EPVO.

Child↗
PubMed2001

Torsade de pointes induced by metoclopramide in an elderly woman with preexisting complete left bundle branch block.

There is a growing list of drugs implicated in acquired long QT syndrome and torsade de pointes. However, the torsadogenic potential of metoclopramide, a commonly used antiemetic and prokinetic drug, has not been reported in the literature, despite its chemical similarity to procainamide. We report on a 92-year-old woman with preexisting complete left bundle branch block who developed torsade de pointes after intravenous and oral administration of metoclopramide. This patient also developed torsade de pointes when cisapride and erythromycin were given simultaneously. These two episodes were suppressed successfully after discontinuing the offending drugs and administering class IB drugs. This is the first documentation that metoclopramide provokes torsade de pointes clinically. Metoclopramide should be used cautiously in patients with a risk of torsade de pointes.

Aged↗
PubMed2000

Telomere-binding and Stn1p-interacting activities are required for the essential function of Saccharomyces cerevisiae Cdc13p.

Yeast Saccharomyces cerevisiae Cdc13p is the telomere-binding protein that protects telomeres and regulates telomere length. It is documented that Cdc13p binds specifically to single-stranded TG(1-3) telomeric DNA sequences and interacts with Stn1p. To localize the region for single-stranded TG(1-3) DNA binding, Cdc13p mutants were constructed by deletion mutagenesis and assayed for their binding activity. Based on in vitro electrophoretic mobility shift assay, a 243-amino-acid fragment of Cdc13p (amino acids 451-693) was sufficient to bind single-stranded TG(1-3) with specificity similar to that of the native protein. Consistent with the in vitro observation, in vivo one-hybrid analysis also indicated that this region of Cdc13p was sufficient to localize itself to telomeres. However, the telomere-binding region of Cdc13p (amino acids 451-693) was not capable of complementing the growth defects of cdc13 mutants. Instead, a region comprising the Stn1p-interacting and telomere-binding region of Cdc13p (amino acids 252-924) complemented the growth defects of cdc13 mutants. These results suggest that binding to telomeres by Cdc13p is not sufficient to account for the cell viability, interaction with Stn1p is also required. Taken together, we have defined the telomere-binding domain of Cdc13p and showed that both binding to telomeres and Stn1p by Cdc13p are required to maintain cell growth.

Cyclin B↗
PubMed2000

Recovery of low-temperature stressed E. coli O157:H7 and its susceptibility to crystal violet, bile salt, sodium chloride and ethanol.

This study was conducted to investigate the alteration of some characteristics of E. coli O157:H7 subjected to various periods of storage at -5, -18 and -28 degrees C. Results revealed that the low-temperature treatments increased the susceptibility of E. coli O157:H7 to crystal violet, bile salt, sodium chloride and ethanol. In general, the susceptibility of E. coli O157:H7 subjected to storage at -18 degrees C increased most significantly. The susceptibility of E. coli O157:H7 to the tested agents increased as the period of low-temperature storage extended, regardless of storage temperature. Among the various nitrogen and carbon sources tested, tryptone and soytone were the most effective nitrogen sources, while glucose and maltose were the most effective carbon sources for the growth of the low-temperature stressed cells. When growing the stressed E. coli O157:H7 in media containing the same nitrogen source or carbon source, their lag period increased as the time of frozen storage increased. It was also noted that in general, the recovery of the low-temperature stressed E. coli O157:H7 was highest on tryptic soy agar followed by Modified eosin methylene blue agar, while recovery on MaConkey sorbitol agar and Modified MaConkey sorbitol agar was lowest.

Bile Acids and Salts↗
PubMed2000

Determination of amphetamine and methamphetamine in serum via headspace derivatization solid-phase microextraction-gas chromatography-mass spectrometry.

This study evaluates solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) to determine trace levels of amphetamine and methamphetamine in serum. Headspace post-derivatization in a laboratory-made design with heptafluorobutyric anhydride vapor following SPME was compared with that without derivatization SPME. The SPME experimental procedures to extract amphetamine and methamphetamine in serum were optimized with a relatively non-polar poly(dimethylsiloxane) coated fiber at pH 9.5, extraction time for 40 min and desorption at 260 degrees C for 2 min. Experimental results indicate that the concentration of the serum matrix diluted to a quarter of original (1:3) ratio by using one volume of buffer solution of boric acid mixed with sodium hydroxide and two volumes of water improves the extraction efficiency. Headspace derivatization following SPME was performed by using 6 microl 20% (v/v) heptafluorobutyric anhydride ethyl acetate solution at an oil bath temperature of 270 degrees C for 10 s. The precision was below 7% for analysis for without derivatization and below 17% for headspace derivatization. Detection limits were obtained at the ng/l level, one order better obtained in headspace derivatization than those achieved without derivatization. The feasibility of applying the methods to determine amphetamine and methamphetamine in real samples was examined by analyzing serum samples from methamphetamine abused suspects. Concentrations of the amphetamine and methamphetamine ranged from 6.0 microg/l (amphetamine) to 77 microg/l (methamphetamine) in serum.

Amphetamines↗
PubMed2000

Cloning and expression of ZAK, a mixed lineage kinase-like protein containing a leucine-zipper and a sterile-alpha motif.

A novel mixed lineage kinase-like protein ZAK, containing a leucine-zipper (LZ) and a sterile-alpha motif (SAM), was cloned. This cDNA has 2456 bp and encodes a protein of 800 amino acids that contains a kinase catalytic domain, a leucine-zipper and a SAM. The molecular weight of this protein is 91kDa. Northern blot analysis revealed that the expression of this ZAK gene is found in various parts of human tissues. We also found that ZAK proteins might form homodimers or oligomers in mammalian cells. MLKs have been proposed to function as mitogen-activated protein kinase kinase kinase in pathways leading to MAPK cascade. The expression of ZAK in mammalian cells specifically leads to the activation of the JNK/SAPK pathway as well as the activation of transcription factor, NF-kappaB. Overexpression of the ZAK gene induces the apoptosis of a hepatoma cell line.

Amino Acid Sequence↗
PubMed2000

Tyr115, gln165 and trp209 contribute to the 1, 2-epoxy-3-(p-nitrophenoxy)propane-conjugating activity of glutathione S-transferase cGSTM1-1.

We investigated the epoxidase activity of a class mu glutathione S-transferase (cGSTM1-1), using 1,2-epoxy-3-(p-nitrophenoxy)propane (EPNP) as substrate. Trp209 on the C-terminal tail, Arg107 on the alpha4 helix, Asp161 and Gln165 on the alpha6 helix of cGSTM1-1 were selected for mutagenesis and kinetic studies. A hydrophobic side-chain at residue 209 is needed for the epoxidase activity of cGSTM1-1. Replacing Trp209 with histidine, isoleucine or proline resulted in a fivefold to 28-fold decrease in the k(cat)(app) of the enzyme, while a modest 25 % decrease in the k(cat)(app) was observed for the W209F mutant. The rGSTM1-1 enzyme has serine at the correponding position. The k(cat)(app) of the S209W mutant is 2. 5-fold higher than that of the wild-type rGSTM1-1. A charged residue is needed at position 107 of cGSTM1-1. The K(m)(app)(GSH) of the R107L mutant is 38-fold lower than that of the wild-type enzyme. On the contrary, the R107E mutant has a K(m)(app)(GSH) and a k(cat)(app) that are 11-fold and 35 % lower than those of the wild-type cGSTM1-1. The substitutions of Gln165 with Glu or Leu have minimal effect on the affinity of the mutants towards GSH or EPNP. However, a discernible reduction in k(cat)(app) was observed. Asp161 is involved in maintaining the structural integrity of the enzyme. The K(m)(app)(GSH) of the D161L mutant is 616-fold higher than that of the wild-type enzyme. In the hydrogen/deuterium exchange experiments, this mutant has the highest level of deuteration among all the proteins tested. We also elucidated the structure of cGSTM1-1 co-crystallized with the glutathionyl-conjugated 1, 2-epoxy-3-(p-nitrophenoxy)propane (EPNP) at 2.8 A resolution. The product found in the active site was 1-hydroxy-2-(S-glutathionyl)-3-(p-nitrophenoxy)propane, instead of the conventional 2-hydroxy isomer. The EPNP moiety orients towards Arg107 and Gln165 in dimer AB, and protrudes into a hydrophobic region formed by the loop connecting beta1 and alpha1 and part of the C-terminal tail in dimer CD. The phenoxyl ring forms strong ring stacking with the Trp209 side-chain in dimer CD. We hypothesize that these two conformations represent the EPNP moiety close to the initial and final stages of the reaction mechanism, respectively.

Amino Acid Substitution↗
PubMed2000

The crystal structure of phosphoglucose isomerase/autocrine motility factor/neuroleukin complexed with its carbohydrate phosphate inhibitors suggests its substrate/receptor recognition.

Phosphoglucose isomerase catalyzes the reversible isomerization of glucose 6-phosphate to fructose 6-phosphate. In addition, phosphoglucose isomerase has been shown to have functions equivalent to neuroleukin, autocrine motility factor, and maturation factor. Here we present the crystal structures of phosphoglucose isomerase complexed with 5-phospho-D-arabinonate and N-bromoacetylethanolamine phosphate at 2.5- and 2.3-A resolution, respectively. The inhibitors bind to a region within the domains' interface and interact with a histidine residue (His(306)) from the other subunit. We also demonstrated that the inhibitors not only affect the enzymatic activity of phosphoglucose isomerase, but can also inhibit the autocrine motility factor-induced cell motility of CT-26 mouse colon tumor cells. These results indicate that the substrate and the receptor binding sites of phosphoglucose isomerase and autocrine motility factor are located within close proximity to each other. Based on these two complex structures, together with biological and biochemical results, we propose a possible isomerization mechanism for phosphoglucose isomerase.

Animals↗
PubMed2000

Capillary zone electrophoresis for the determination of atovaquone in serum.

A rapid and simple capillary zone electrophoresis (CZE) method has been developed for the determination of atovaquone in serum. The drug was extracted from equine serum-chloroform (1:3, v/v) at greater than 80% recovery and assayed in buffer containing 25 mM sodium borate (pH 9.1) and 25% acetonitrile. A 100 microm I.D. fused-silica capillary was used and the detection was by UV-diode array at 254 nm; the migration time was approximately 8 min. Intra- and inter-assay variabilities were less than 7.8% and 5.8%, respectively, and the accuracy of the assay (expressed as % bias) ranged from 4.5 to -5.2%. The working assay range was from 2 to 100 microg/ml. This sensitivity could be increased by concentrating during the extraction procedure. Replacement of acetonitrile with 75 mM surfactant 3-(dimethyldodecylammonio)propanesulfonate gave similar sensitivity and provided an additional option to facilitate the separation of atovaquone on multiple-drug samples.

Antifungal Agents↗
PubMed2000

Growth of bifidobacteria in soymilk and their survival in the fermented soymilk drink during storage.

Growth of Bifidobacterium infantis CCRC 14633 and B. longum B6, in soymilk was investigated in the present study. It was found that soymilk could support the growth of both organisms tested. B. infantis grew better than B. longum in soymilk. Supplementation of bifitose (isomaltooligosccharie), glucose, lactose or galactose to soymilk increased the growth of B. infantis and B. longum as determined after 48 h of fermentation. On the other hand, addition of yeast extract, peptone, tryptone, casitone or N-Z-Case plus to soymilk enabled B. infantis to reach its maximum population in a shorter cultivation time of 24 h. Acid production by B. longum and B. infantis in soymilk was mainly non-growth associated, while in the yeast extract-supplemented soymilk, acid produced by B. infantis was found to be growth-associated. Populations of B. longum reduced more than did B. infantis in the prepared fermented soymilk drink during storage period. Viable population of both test organisms reduced less in the fermented drink held at 5 degrees C than at 25 degrees C. After a 10-day storage at 5 degrees C, viable B. infantis and B. longum reduced by 0.44 and 3.18 log CFU/ml, respectively, in the fermented drink. Addition of sucrose to the fermented drink resulted in an increased reduction of viable bifidobacteria during the storage period. This phenomenon was most prominent with B. infantis in the fermented drink held at 25 degrees C.

Animals↗
PubMed2000

Production and molar yield of 2-phenylethanol by Pichia fermentans L-5 as affected by some medium components.

In this study, the effects of carbon sources and various levels of sucrose (0-30%) yeast extract (0-1.25%) and phenylalanine (0-0.2%) on the production of 2-phenylethanol by Pichia fermentans L-5 were investigated. Results revealed that among the 11 carbon sources tested, glycerol and sucrose were suitable carbon sources for P. fermentans L-5 resulting in production of higher amounts of 2-phenylethanol. In the medium that contained 18% sucrose, P. fermentans L-5 produced the highest amount of 2-phenylethanol, 283.4 mg/l with a molar yield of 0.77, was noted among the various levels of sucrose tested. Increasing the amount of phenylalanine added to the culture medium to 1.0% resulted in increased production of phenylethanol. Enhanced production of 2-phenylethanol, 453.1 mg/l by P. fermentans L-5 with a molar yield of 0.71 for phenylethanol was obtained in the medium containing 18% sucrose, 0.25% yeast extract and 0.1% phenylalanine after 16 h of fermentation.

Journal Article↗
PubMed2000

Growth and survival of Escherichia coli O157:H7 and Listeria monocytogenes in egg products held at different temperatures.

Growth and survival of Escherichia coli O157:H7 and Listeria monocytogenes in steamed eggs and scrambled eggs held at different temperatures (5, 18, 22, 37, 55, and 60 degrees C) were investigated in the present study. Among the holding temperatures tested, both pathogens multiplied best at 37 degrees C followed by 22, 18, and 5 degrees C. In general, E. coli O157:H7 grew better in the egg products than L. monocytogenes did at all the storage temperatures tested except at 5 degrees C. E. coli O157:H7 did not grow in steamed eggs and scrambled eggs held at 5 degrees C. L. monocytogenes showed a slight population increase of approximately 0.6 to 0.9 log CFU/g in these egg products at the end of the 36-h storage period at 5 degrees C. The population of both pathogens detected in the egg products was affected by the initial population, holding temperature, and length of the holding period. It was also noted that L. monocytogenes was more susceptible than E. coli O157:H7 in steamed eggs held at 60 degrees C. After holding at 60 degrees C for 1 h, no detectable viable cells of L. monocytogenes with a population reduction of 5.4 log CFU/g was observed in steamed eggs, whereas a lower population reduction of only approximately 0.5 log CFU/ml was noted for E. coli O157:H7.

Animals↗
PubMed2000

The role of free to total prostate-specific antigen ratio for prostate cancer in screening patients with total serum levels between 4 and 20 ng/ml.

BACKGROUND: We retrospectively tried to determine if the free to total prostate-specific antigen (f/t PSA) ratio could improve the specificity of PSA in prostate cancer screening of patients with total serum levels between 4 and 20 ng/ml. METHODS: Two hundred ninety-five patients with serum PSA levels from 4 to 20 ng/ml had undergone sextant prostate needle biopsy. Each patient had no prior history of prostate cancer, acute urine retention, or prostatitis. Prebiopsy free PSA values were measured in 155 patients. Total PSA levels were determined with the AxSYM enzyme-linked immunosorbent assay. Free PSA levels were measured with the AxSYM microparticle enzyme immunoassay. RESULTS: Mean f/t PSA ratios were 0.114+/-0.004 in men of the cancer group and 0.161+/-0.008 in men of the benign group (p<0.002). Based on the analysis of sensitivity and specificity in relation to f/t PSA ratios, use of the 18% cutoff point could detect 89% of cancer cases, and at the same time could avoid 35% of unnecessary prostate biopsies. The areas under the receiver-of-characteristic curve for f/t PSA ratio and total PSA were 0.649 and 0.545, respectively. CONCLUSION: Serum f/t PSA ratios were significantly lower in patients with prostate cancer than in patients with benign disease. The determination of an appropriate f/t PSA ratio should be based on the generated data such as that demonstrated in this study in order to improve diagnostic accuracy and specificity for patients with equivocal PSA values and to avoid conducting unnecessary prostate biopsies.

Aged↗