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C S Chen

Publications and source records attributed to C S Chen.

At least 163 records · Page 9Linked to original sources
PubMed1993

New fluorescent probes for protein kinase C. Synthesis, characterization, and application.

Fluorescent derivatives of the bisindolylmaleimide inhibitors of protein kinase C (PKC) were synthesized and tested with respect to their inhibitory potency, specificity, and usefulness as fluorescent cytological stains for PKC. Several of the fluorescent bisindolylmaleimide derivatives (fim-1, fim-2, and rim-1) acted as ATP-competitive catalytic site inhibitors and retained much of the potency and specificity of the parental compound. The R6-C1 and the PKC beta 1-overexpressing R6-PKC3 cell lines were used for testing fim-1 and rim-1 as cytological stains for PKC. Comparisons showed that the R6-PKC3 cells stained much more brightly than R6-C1 cells. When R6-PKC3 cells were treated with the phorbol ester phorbol 12-myristate 13-acetate (PMA) for 30 min, staining with fim-1 or anti-PKC beta 1 revealed a dramatic translocation of PKC to the cell periphery. When R6-PKC3 cells were exposed to PMA for 24 h to down-regulate PKC, cytoplasmic staining was drastically reduced. Staining patterns obtained with an antibody specific for PKC beta 1 and with fim-1 were remarkably similar except for mitochondrial staining, which was only seen with fim-1. A closer examination of the mitochondrial staining showed that mitochondria convert from filamentous to punctate shapes and cluster around the nucleus when cells are treated with PMA. This punctate morphology, perinuclear clustering, and staining with fim-1 persists when PKC is down-regulated. Overall, these results indicate that fim-1 and rim-1 can serve as useful fluorescent probes for PKC. The mitochondrial staining may be due to a PKC isoform resistant to down-regulation.

Animals↗
PubMed1993

Molecular rearrangements on chromosome 11q23 predominate in infant acute lymphoblastic leukemia and are associated with specific biologic variables and poor outcome.

Acute lymphoblastic leukemia (ALL) in infants generally shows distinctive biologic features and has a poor prognosis. Cytogenetic studies indicate that many infant leukemias have chromosome 11q23 translocations. Because of these findings and the distinct clinical features of infant leukemia, we investigated 30 cases of infant ALL for molecular defects of 11q23. Fourteen cases had cytogenetic abnormalities of 11q23, and all of them showed 11q23 rearrangements at the molecular level. An additional seven cases also had 11q23 molecular rearrangements, including one with normal cytogenetic analysis. Molecular abnormalities of 11q23 were significantly correlated with adverse prognostic factors, including age under 6 months, hyperleukocytosis, CD10- phenotype, and early treatment failure. Molecular analysis identified a group of infants with germline 11q23 that had a very good treatment outcome with a projected event-free survival of 80% at median follow-up of 46 months compared to 15% in infants with rearranged 11q23 (P < .001). These findings suggest that a high proportion (70%) of infants with ALL have 11q23 rearrangements and that these rearrangements are not always detectable by cytogenetic analysis. The presence of germline 11q23 DNA may identify a subgroup of infant ALL patients with a good outcome using current therapy and a different etiology for their ALL.

Blotting, Southern↗
PubMed1993

Nucleosides. 5. Synthesis of guanine and formycin B derivatives as potential inhibitors of purine nucleoside phosphorylase.

In an effort to develop potent human purine nucleoside phosphorylase (PNP) inhibitors as immunosuppressive and chemotherapeutic agents, several 8-aminoguanine derivatives were synthesized and evaluated as potential PNP inhibitors. These studies were designed to investigate the hydrophobic effect of a substituent on the N-9 of the purine heterocycle and/or the C-5' positions. Compounds such as 8-aminoguanosine, guanosine, formycin B, and 8-aminoacyclovir containing a p-(fluorosulfonyl)benzoyl moiety were synthesized. The affinity of these compounds to erythrocytic PNP was determined and none of these compounds showed a better affinity than those of the parent compounds. However, we found that the effect of hydrophobicity at the N-9 and the C-5' positions might play an important role in binding to the active site of PNP. Thus, 8-amino-5'-deoxy-5'-(phenylthio)guanosine (19) was found to be the best inhibitor in this series of compounds with a Ki = 0.45 microM.

Binding Sites↗
PubMed1993

Purification and characterization of novel "2-arylpropionyl-CoA epimerases" from rat liver cytosol and mitochondria.

Investigation on the biochemical isomerization of ibuprofen led us to the successful purification of "2-arylpropionyl-CoA epimerase" from rat liver cytosol and mitochondria. The purified enzymes from both subcellular fractions exhibit similar physical and catalytic properties and are distinctly different from rat liver methylmalonyl-CoA epimerase. Both are monomeric proteins with an apparent molecular mass of 42 kDa and show similar contents of most amino acids. Their UV spectra gave no indication of any bound cofactors, and their enzyme activities were not affected by exposure to EDTA or metal ions (except Cu2+). These results suggest that the cytosolic and mitochondrial epimerases may be structurally related. The purified enzymes catalyze the epimerization of various 2-arylpropionyl-CoAs with some degree of stereochemical differentiation. For 2-(4-isobutylphenyl)propionyl-CoA, the equilibrium constant was estimated to be 1.5 in favor of the R-isomer. Evidence indicated that the proton exchange may be mediated by a 2-base mechanism and that a carboxylic residue in the active site may serve as a general base for proton abstraction.

Amino Acids↗
PubMed1993

A 13C NMR study on ibuprofen metabolism in isolated rat liver mitochondria.

A 13C NMR approach was taken to study the biotransformation of (R)- and (S)-[2-13C,2-2H]ibuprofen-CoA in isolated rat liver mitochondria. The 13C chemical shift induced by 2H substitution for the C-2 of [2-13C,2-2H]-ibuprofen-CoA is about 0.5 ppm relative to the corresponding 1H-bearing thioester. The C-2 resonances for [2-13C]- and [2-13C,2-2H]ibuprofen-CoA are 5 ppm downfield with respect to their acid counterparts. Consequently, this technique permits real time analyses of the metabolic fate of the doubly labeled substrate in a quantitative manner. The initial rate of the epimerization of (S)-[2-13C,2-2H]ibuprofen-CoA relative to the (R)-counterpart by intact mitochondria was estimated to be 1.5, which is in line with the equilibrium constant determined with the purified epimerase. Contrary to the reports by other groups, this 13C NMR study did not find spontaneous hydrolysis of the CoA-thioester upon being exposed to intact mitochondria. Current focus of this investigation is to extend this NMR methodology to the levels of whole cells and live animals to gain a better understanding of the enantioselective metabolism of ibuprofen.

Animals↗
PubMed1993

Differential expression of plasminogen activators and their inhibitors in an organotypic skin coculture system.

Using immunohistochemistry and in situ hybridization, we have characterized the expression and localization of components of the plasminogen activator proteolytic cascade in an organotypic coculture system which consists of a "dermal" portion (human dermal fibroblasts throughout a collagen matrix) and a stratified, well-differentiated epidermal portion. Specifically, the following components were examined: the enzymes urokinase-type plasminogen activator and tissue-type plasminogen activator and their type 1 and type 2 inhibitors. Urokinase plasminogen activator mRNA and antigen were found predominantly in the least differentiated, basal keratinocytes; in some fields there was also faint deposition of antigen beneath the basal cells. The distribution of plasminogen activator inhibitor type 1 was similar to that of urokinase, except that inhibitor type 1 antigen deposition beneath the basal cells appeared more intense and uniform. In contrast to the results with urokinase plasminogen activator and inhibitor type 1, tissue plasminogen activator mRNA and antigen were localized focally in the suprabasal, i.e. more differentiated, keratinocytes. Plasminogen activator inhibitor type 2 mRNA and antigen were detected in most epidermal layers, but were more intense suprabasally and often spared the basal layer. These studies demonstrate that the same type of cell, i.e. the keratinocyte, can express different components of the plasminogen activator cascade depending on its state of differentiation. The change in expression of plasminogen activator cascade components with keratinocyte differentiation suggests distinct epidermal functions for these components, related to cell-matrix interaction and epidermal differentiation.

Cell Differentiation↗
PubMed1993

Monitoring of cyclosporin A levels with radioimmunoassay in renal transplant recipients: comparison of monospecific and nonspecific assays.

Patients receiving cyclosporin A (CsA) therapy should be monitored carefully in order to avoid side effects and maintain immunosuppression. Radioimmunoassay is one of the most commonly used methods of monitoring CsA levels. The decision to use whole blood vs plasma or monospecific vs nonspecific monoclonal antibodies for the measurement of CsA levels has been a controversial issue. In this study, CsA levels in the whole blood and plasma were measured simultaneously with INCSTAR specific monoclonal antibodies in 20 renal transplant recipients (group A). There was a significant correlation between the CsA levels in the whole blood and plasma (R2 = 0.7379, p < 0.00001). However, at the therapeutic limit, the correlation was not good. The whole blood/plasma CsA concentration ratios were not correlated with the hematocrits of the patients. In another group of 20 renal transplant recipients (group B), CsA levels in whole blood and plasma were measured simultaneously with INCSTAR nonspecific monoclonal antibodies. There was a significant correlation between the CsA levels in whole blood and plasma (R2 = 0.6714, p < 0.00001). The whole blood/plasma ratios were significantly correlated with the hematocrits (R2 = 0.5457, p = 0.0002). The later finding could be due to the extensive cross-reactivity of nonspecific monoclonal antibodies with CsA metabolites, which are almost exclusively bound to the erythrocytes. The hematocrits in renal transplant recipients usually show significant change over a period of time. The plasma level may be more stable in such cases. However, measurement of whole blood levels also has several advantages, mainly from a technical aspect.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclosporine↗
PubMed1993

[Pheochromocytoma nuclear pattern analysis by flow cytometry].

Flow cytometric nuclear DNA analyses were performed on paraffin-embedded tissue samples taken from 39 patients with pheochromocytoma treated between 1981 and 1992. The Hedley technique was used for measurement of nuclear DNA contents. Only 30 cases out of the 39 tumors were available for the determination of DNA ploidy analyses. Ten cases (33.3%) showed a diploidy pattern, 8-cases (27%) showed an aneuploidy pattern and 12 cases (40%) revealed a tetraploidy pattern. Four cases of malignant pheochromocytoma with regional or distal metastasis had been noted during a mean follow-up period of 4.75 years. All these four cases showed tetraploidy nuclear pattern with vascular invasion on pathological examination, which was statistically significant (p < 0.001) in differentiation between benign and malignant pheochromocytoma. About one third of patients with tetraploidy appeared to have malignant tendencies and this was statistically significant (p < 0.05). None of the patients with either diploidy or aneuploidy pattern had disease progression. The location of the tumor (adrenal vs. extra-adrenal) and 24 hours urine total vanillylmandelic acid (VMA) amounts were not significantly different from the diploid, aneuploid or tetraploid groups. These results suggested that nuclear DNA ploidy pattern is an important independent, and useful prognostic factor for patients with pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1993

[Transtympanic electrocochleography in Menière's disease].

In order to examine the usefulness of the electrocochleography (ECoG) in the diagnosis of Menière's disease and establish the diagnostic criteria in Chinese, transtympanic ECoG was performed on 18 normal ears, 22 Menière's ears and 14 ears with cochlear type sensorineural hearing loss other than Menière's disease. Although the Menière's ears had larger mean summating potential (SP) than the normal ears, the difference between both groups was not statistically significant. The mean amplitude and latency of the action potential (AP) in Menière's ears decreased and elongated significantly, but neither was sensitive enough in diagnosing Menière's disease. The SP/AP amplitude ratio not only made significant difference among 3 groups, but also had good diagnostic sensitivity (59.1%) and specificity (92%) in diagnosing Menière's disease while using the 95% upper confidence limit of the normative data (i.e., 34%). The SP/AP amplitude ratio of Menière's ears tended to increase while the mean hearing level of 4-8 KHz deteriorated. Also, abnormal enlargement of the SP/AP amplitude ratio in Menière's disease tended to be the result of decreased AP amplitude.

Action Potentials↗
PubMed1993

[The application of non-annealing thermoluminescent dosimetry (TLD)].

Conventional use of Thermoluminescence (TL) in radiation dosimetry is very time-consuming. It requires repeating the procedures of preheating and annealing. In an attempt to simplify these procedures, we conducted an experiment of non-annealing TL dosimetry. This article reports the experiment's results. We adopted Lithium Fluoride (LiF) chip (TLD-100) in polystyrene under the exposure of Co-60, and the result was taken by HAR-SHAW-4000 TL reading system. The TL response was analyzed, including linearity, reproducibility and fading test. Because non-annealing TL response was greatly influenced by residual electron, TLD calibration curves were separated into two parts: (1) high dose region (HDR, 50-1500 cGy); (2) low dose region (LDR, 0-50 cGy). When TL dosimeters were exposed to a single high does (about 500 cGy), the HDR could be reproduced within 3% and fit a good linearity. For LDR, we had to give up the tail of glow curve in the high temperature region. We could then get good linearity and reproducibility. Furthermore, fading of non-annealing was apparently larger than annealing. We could control the fading of non-annealing was apparently larger than annealing. We could control the fading influence within 1% by taking the TL reading one hour after exposure. On the other hand, a combination of photon and electron exposure was also performed by non-annealing TL dosimetry. The results were compatible with Co-60 exposure in the same system.

Humans↗
PubMed1993

[Ventilation tube insertion for treating adult otitis media with effusion].

The etiologic factors and treatment of otitis media with effusion (OME) in children are well described and established. On the contrary, little has been published with regard to OME in adults and its treatment. To further investigate this problem, we reviewed the records of all adult patients who had received ventilation tube (VT) insertion for OME in VGH-Taipei from 1983 to 1986. There were 335 VT insertions performed on 140 adult patients whose follow-up periods were longer than 6 months. Among them, fifty patients received more than one VT insertion due to recurrence of OME in one or both ears. The average follow-up period was more than 4 years. The coexistence of nasal diseases was found in 46% of the adult OME patients. The mean extrusion time of the VT was 10.2 months. After VT insertions, the improvements of mean air conduction and mean air-bone conduction gap were 10.1 and 11.8 dB respectively. After the extrusion or removal of VT, there was no recurrence of OME in 50 ears (14.9%). Recurrence of OME occurred in 199 ears (59.4%). Dry persistent perforations of the eardrums were found in 27 ears (8.1%). Discharging persistent perforations were noted in 24 ears (7.2%). No recurrence of OME was observed in 24.2% of the ears with serous effusion fluids, whereas only 4.8% of the ears with mucoid fluids were free from recurrence during the follow-up period. Post-intubation otorrhea, which was the most common complication, developed in 92 ears (27.5%). Our results suggest that the recurrence rate of OME after extrusion of VT is high in the adult patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1992

Current seroepidemiology of hepatitis D virus infection among hepatitis B surface antigen carriers of general and high-risk populations in Taiwan.

In order to assess the current seroepidemiology of hepatitis D virus (HDV) infection in Taiwan where hepatitis B virus (HBV) is hyperendemic, a total of 756 voluntary blood donors, 641 prostitutes, 1,014 patients with sexually transmitted diseases (STDs), and 628 drug abusers were studied. Radioimmunoassays were used for testing HBV infection markers and antibody against HDV (anti-HDV) among HBsAg carriers. The anti-HDV prevalence among HBsAg carriers was significantly higher in STD patients (9.6%), prostitutes (33.1%), and drug abusers (68.1%) than in blood donors from the general population (2.2%). The prevalence gradually increased with age in blood donors and STD patients, but reached a plateau at a young age in prostitutes and drug abusers. Males had a higher prevalence than females in blood donors (2.7% vs. 0), STD patients (8.2% vs. 7.5%), and drug abusers (69.0% vs. 57.1%), but the difference was not statistically significant. STD patients with syphilis had a higher prevalence (19.5%) than those affected with non-ulcerating STDs (5.3%). While unlicensed prostitutes had a lower prevalence (13.6%) than licensed prostitutes (44.9%), intravenous drug abusers had a higher prevalence (73.1%) than non-intravenous drug abusers (34.6%). There was a twofold increase in anti-HDV prevalence from 1986 to 1989 among prostitutes, but the prevalence remained unchanged in the general population and drug abusers. HDV infection remains limited to the high-risk groups and spread mainly by promiscuity and needle sharing in Taiwan.

Adult↗
PubMed1992

cDNA cloning and gene expression of the major prolamins of rice.

A full-length cDNA (pS 18) encoding the 16 kDa rice prolamin composed of 158 amino acids was sequenced. Analysis of N-terminal amino acid sequence of a major rice prolamin indicated that an 18 amino acid signal peptide was removed from 16 kDa precursor prolamin to form the 14 kDa prolamin during seed development. Synthesis of the 16 kDa precursor prolamin began around 8 days after flowering (DAF), increased remarkably at 8-11 DAF and gradually reached maximum levels with the maturation of rice seeds.

Amino Acid Sequence↗
PubMed1992

Levels of direct-acting mutagens, total N-nitroso compounds in nitrosated fermented fish products, consumed in a high-risk area for gastric cancer in southern China.

A high gastric cancer mortality in Fujian province (Peoples Republic of China) has been associated with the consumption of certain salted fermented fish products such as fish sauce (FS). We have investigated the levels and nature of N-nitroso compounds (NOC) and genotoxins present, before and after nitrosation, in 49 FS samples collected from villages in this high-risk area, pooled into six samples. The concentrations of total NOC before nitrosation ranged from 0.2 to 16 mumoles/l, and after nitrosation at pH 2 and pH 7, they rose by up to 4800- and 100-fold, respectively. In nitrosated samples, 40-50% of total NOC was not extractable into organic solvents; volatile N nitrosamines accounted for 1-2% and N-nitrosamino acids for 8-16% of total NOC. None of the FS samples exhibited genotoxic activity, but after nitrosation all were weakly active in the SOS chromotest. The highest SOS-inducing potency was observed with nitrosated ethyl acetate extracts of most samples. The formation of methylating agents was measured by incubation of nitrosated FS with DNA and subsequent analysis of 7-methylguanine adduct. 2 of the 6 nitrosated FS samples caused a slight increase in DNA methylation. 1 pooled home-made FS sample (the only one tested) contained tumour promoter-like substances, as measured by expression of certain EBV genes in Raji cells. HPLC fractionation of ethyl acetate extracts of FS samples allowed identification of three UV-absorbing peaks that, upon nitrosation, produced direct-acting genotoxins. This genotoxicity was partly ascribed to the formation of nitrite-derived arene diazonium cations that were characterized by a coupling reaction with N-ethyl-1-naphthylamine and thin-layer chromatography.

China↗
PubMed1992

Morphological changes in the respiratory system of mice after inhalation of mosquito-coil smoke.

Male ICR mice were exposed to mosquito-coil smoke with d-allethrin or without d-allethrin at airborne particles concentration of 1.27 mg/m3, 7 h/day, 7 days/week for 1, 3, 6, and 12 months. Additional groups of air exposure animals served as controls. At 1 month after exposure, the histopathological lesions included the loss of cilia, and the alteration of the alveolar pattern in the treated and the sham mice. Volume fractions of the type I and II cells were smaller (0.028 +/- 0.006, 0.044 +/- 0.002) in the treated group than those of the controls (0.049 +/- 0.008, 0.059 +/- 0.003). Fractions of the lumina of vessels and the vessel wall decreased in both the treated and the sham groups as compared to the control group. However, the volume fraction of alveolar air space increased significantly in both treated and sham groups as compared to the controls (0.619 +/- 0.022, 0.685 +/- 0.018 vs. 0.507 +/- 0.025). After 3- and 6-months exposure, the lesions observed in the trachea persisted. The intercellular fibrosis in the lung was increased in both the treated and sham groups at 6 months and became more severe at the later stages. At 12-months exposure, an increase in vascularity of the alveolar wall was observed and fine granular debris was frequently present in the alveolar space. The fraction volumes of the type II cells in the treated group and the type I cells in the sham group were significantly increased (0.059 +/- 0.010, 0.042 +/- 0.003) compared with those of the controls (0.038 +/- 0.008, 0.033 +/- 0.003). However, the fraction volume of air space and vessel lumen were not different among the three groups. Finally, there were no differences in the morphologic appearance of the airways and the lung periphery between the treated and the sham-exposed animals.

Allethrins↗
PubMed1992

Inhibition of tonoplast ATPase by 2',3'-dialdehyde derivative of ATP.

The 2',3'-dialdehyde derivative of ATP (dial-ATP) has been shown to be an affinity label for the ATP binding site of the H(+)-ATPase from tonoplast of etiolated mung bean seedlings (Vigna radiata L.). The dial-ATP caused marked inactivation of enzymatic activities of both membrane-bound and soluble ATPase and its associated proton translocation. The inactivation was reversible, but could be stabilized by NaBH(4). The sodium dodecyl sulfatepolyacrylamide gel electrophoresis pattern revealed that the dial-ATP binding site was in the large (A) subunit of ATPase. The inhibition could be substantially protected by its physiological substrate ATP, pyrophosphate, and nucleotides in the decreasing order: ATP > pyrophosphate > ADP = AMP > GTP > CTP = UTP. A Lineweaver-Burk plot showed that the mode of inhibition was competitive with respect to ATP. Loss of ATPase activity followed pseudo-first order kinetics with a K(i) of 4.1 millimolar, a minimum inactivation half-time of 20 seconds, and a pseudo-first order rate constant of 0.035 s(-1). The double logarithmic plot of apparent rate constant versus dial-ATP concentration gave a slope of 0.927, indicating that inactivation results from reaction of at least one lysine residue at the catalytic site of the large subunit. Labeling studies with [(3)H]dial-ATP indicate that the incorporation of approximately 1 mole of dial-ATP per mole ATPase is sufficient to completely inhibit the ATPase. A working model of nonequivalent subunits for enzymatic mechanism of vacuolar ATPase is suggested.

Journal Article↗
PubMed1992

Subcapsular hematoma of spleen--a complication following extracorporeal shock wave lithotripsy for ureteral calculus.

Splenic trauma with hematoma following extracorporeal shock wave lithotripsy (ESWL) is very rare. We reported a case of subcapsular hematoma of spleen with impending rupture following ESWL for ureteral calculus. This case was noted to have liver cirrhosis and splenomegaly, and received a total of 2000 shock waves under 18 kilovoltage. The subcapsular hematoma occurred 2 months later. Splenectomy was undertaken for a symptomatic huge subcapsular hematoma and thrombocytopenia. We reviewed the literature and concluded that portal hypertension with severe coagulopathy are contraindications for ESWL, even in case with ureteral calculus.

Female↗