Biomedical subjects

M C Liu

Publications and source records attributed to M C Liu.

At least 55 records · Page 3Linked to original sources

PubMed2000

Retinoic acid-mediated G1 arrest is associated with induction of p27(Kip1) and inhibition of cyclin-dependent kinase 3 in human lung squamous carcinoma CH27 cells.

Retinoids are promising agents for the prevention and treatment of several human malignancies including lung cancer. In this study, the effect of retinoic acid (RA) on cell growth and the mechanism of growth modulation were examined in human lung squamous carcinoma CH27 cells. Here we report that RA mediated the dose- and time-dependent growth arrest in G1 phase, accompanied by the up-regulation of p27(Kip1) and the down-regulation of the cyclin-dependent kinase 3 (Cdk3) and p21(CIP1/Waf1) proteins. Furthermore, RA-induced growth arrest of CH27 cells was also associated with increased retinoic acid receptor beta (RARbeta) and reduced c-Myc expression. However, RA had no effect on the levels of cyclins A, D1, D3, E, or H, or on Cdk2, Cdk4, Cdk5, CDk6, Cdk7, p16(Ink4A), p15(Ink4B), p53, or pRb proteins in CH27 cells. Evaluation of the kinase activity of cyclin-Cdk complexes showed that RA increases p27(Kip1) expression in CH27 cells leading to markedly reduced cyclin A/Cdk2 kinase activity and slightly reduced cyclin E/Cdk2 kinase activity, with no effect on cyclin D/Cdk4 and cyclin D/Cdk6 activities. Moreover, coincident with the decrease in kinase activity was a drastic increase in cyclin A-bound p27(Kip1). These results suggest that increases in the levels of p27(Kip1) and its binding to cyclin A, as well as reduction of Cdk3 protein expression, are strong candidates for the cell cycle regulator that prevents the entry into the S phase in RA-treated CH27 cells, with prolongation of G1 phase and inhibition of DNA synthesis.

CDC2-CDC28 Kinases↗

PubMed2000

Mutational analysis of the substrate binding/catalytic domains of human M form and P form phenol sulfotransferases.

Human monoamine (M) form and simple phenol (P) form phenol sulfotransferases (PSTs) are greater than 93% identical in their primary sequences and yet display distinct substrate specificities and other enzymatic properties. Through the generation and characterization of a series of chimeric PSTs, we have previously demonstrated two highly variable regions within their sequences to be responsible for determining their substrate phenotypes (Sakakibara, Y., Takami, Y., Nakayama, T., Suiko, M., and Liu, M.-C. (1998) J. Biol. Chem. 273, 6242-6247). By employing the site-directed mutagenesis technique, the present study aims to identify and quantitatively evaluate the specific amino acid residues critical to the substrate binding and catalysis in these two enzymes. Twelve mutated M-PSTs and seven mutated P-PSTs were generated, expressed, and purified. Enzymatic characterization showed that, of the twelve mutated M-PSTs, mutations at residues Asp-86, Glu-89, and Glu-146 resulted in a dramatic decrease in V(max)/K(m) with dopamine as substrate, being greater than 450 times for the D86A/E89I/E146A mutated M-PST. With p-nitrophenol as substrate, the V(max)/K(m) determined for the D86A/E89I/E146A-mutated M-PST increased more than 25 times and approached that determined for the wild-type P-PST. These results indicated that the concerted action of the three mutated residues (D86A, E89I, and E146A) is sufficient for the conversion of the substrate phenotype of M-PST to that of P-PST. Among the mutated P-PSTs, the I89E- and A146E-mutated P-PSTs displayed considerable deviations in V(max)/K(m) with dopamine or p-nitrophenol as substrate. No corresponding changes, however, were detected with the opposite compound as substrate. These results indicated that, in contrast to M-PST, mutations at Ala-86, Ile-89, and Ala-146 to the corresponding residues in M-PST are not sufficient for rendering the change of P-PST substrate phenotype to that of M-PST. For both M-PSTs and P-PSTs, mutations at Lys-48 or His-108 led to the loss of sulfotransferase activities, indicating their importance in the catalytic mechanism.

Amino Acid Sequence↗

PubMed2000

Sulfation of environmental estrogen-like chemicals by human cytosolic sulfotransferases.

To investigate whether sulfation, a major Phase II detoxification pathway in vivo, can be employed as a means for the inactivation/disposal of environmental estrogens, recombinant human cytosolic sulfotransferases were prepared and tested for enzymatic activities with bisphenol A, diethylstilbestrol, 4-octylphenol, p-nonylphenol, and 17alpha-ethynylestradiol as substrates. Of the seven recombinant enzymes examined, only SULT1C sulfotransferase #1 showed no activities toward the environmental estrogens tested. Among the other six sulfotransferases, the simple phenol (P)-form phenol sulfotransferase and estrogen sulfotransferase appeared to be considerably more active toward environmental estrogens than the other four sulfotransferases. Metabolic labeling experiments revealed the sulfation of environmental estrogens and the release of their sulfated derivatives by HepG2 human hepatoma cells. Moreover, sulfated environmental estrogens appeared to be incapable of penetrating through the HepG2 cell membrane.

Arylsulfotransferase↗

PubMed2000

Extensive surface phenotyping of alveolar macrophages in interstitial lung disease.

There is increasing evidence implicating activated macrophages in the pathogenesis of interstitial and other lung diseases. We investigated whether there was a unique pattern of cell surface expression that constituted a disease-specific phenotype on alveolar macrophages from patients with interstitial lung disease (ILD). Macrophage cell surface receptor expression of 19 selected markers was assessed by indirect immunofluorescence and flow cytometry in bronchoalveolar lavage (BAL) fluids from patients with idiopathic pulmonary fibrosis (IPF, n = 4), scleroderma (SCL-ILD, n = 14), mild asthma (n = 7), allergy without asthma (n = 2), and normal subjects (n = 9). There was increased expression of adhesion receptors (CD11c, CD29, CD36, CD44, CD49e, CD54), receptors involved in signal transduction and/or inflammation (CD13, CD45, CD53), and other markers (CD9, CD52, CD71, CD98, HLA Class I) on macrophages from ILD patients compared to the non-ILD group. Most markers upregulated on macrophages in ILD were significantly inversely correlated with clinical parameters of disease activity such as FEV(1), FVC, and DL(CO) and positively correlated with numbers of BAL neutrophils and eosinophils. Increased expression of several cell surface markers suggests that activated alveolar macrophages may contribute to the pathophysiology of IPF and SCL-ILD.

Adult↗

PubMed2000

Influence of renal function on the pharmacokinetics of cerivastatin in normocholesterolemic adults.

OBJECTIVE: The influence of impaired renal function on the pharmacokinetics of single and multiple doses of cerivastatin was evaluated in this nonrandomized, non-blinded, 7-day, multiple-dose study. METHODS: Thirty-five adults between the ages of 21 years and 75 years with normal renal function (CL(CR) >90 ml/min/1.73 m2, n = 9), or patients with either mild (CL(CR) 61 ml/min/1.73 m2 to < or =90 ml/min/1.73 m2, n = 9), moderate (CL(CR) 30 ml/min/1.73 m2 to < or =60 ml/ min/1.73 m2, n = 8), or severe (CL(CR) <30 ml/min/ 1.73 m2, but not on dialysis, n = 9) renal impairment were given cerivastatin 0.3 mg daily each evening for 7 days. The steady-state pharmacokinetics of cerivastatin, including the area under the concentration-time curve (AUC)0-24, peak plasma concentration (Cmax), time to reach Cmax (tmax) and elimination half-life (t1/2), were determined on day 1 and day 7. The logarithm of the pharmacokinetic variables was analyzed using analysis of variance (ANOVA). Safety assessments included physical examination, fundoscopy, vital signs, electrocardiogram (ECG), adverse events, and laboratory safety indices. RESULTS: The day-1 AUC in patients with mild renal impairment was similar to that of patients with normal function (19.6 microg/h/l vs 19.2 microg/h/l, respectively). However, the AUC for cerivastatin patients with moderate or severe renal impairment was 40-60% higher (30.8 microg/h/l and 29.0 microg/h/l, respectively). Cmax values for patients with normal, mild, moderate, and severe renal impairment were 3.3, 3.4, 4.6, and 5.2 microg/l, respectively. This modest increase in plasma cerivastatin levels is nearly equivalent to a 0.4-mg daily dose, which has been recently approved in the United States. The mean t1/2 of cerivastatin was less than 4.5 h in all patients, indicating that renal dysfunction did not promote cerivastatin accumulation. This observation was confirmed by the finding that the cerivastatin plasma levels on day 1 and day 7 were similar in all patient groups. Furthermore, the mean AUC and Cmax values for both demethylated and hydroxylated cerivastatin were similar in the patients with the most severe renal dysfunction to the corresponding values in healthy subjects. Cerivastatin was well tolerated in all patients irrespective of renal function. Adverse events were observed in 37% of the subjects; nearly all were mild and generally of short duration, and most resolved without intervention. Incidence of adverse events was similar across all three renal groups and the control group. There were no clinically significant laboratory changes other than those consistent with renal disease. CONCLUSION: This study demonstrates that dosage adjustment of the daily 0.3-mg cerivastatin dose in patients with significant renal impairment is likely unnecessary.

Adult↗

PubMed2000

Unique features of breast cancer in Taiwan.

Between April 1990 and December 1997, 811 consecutive patients with 830 newly diagnosed breast cancers having their primary treatments in our institution were included in this study. Sixty three percent of breast cancer patients were premenopausal. The early-onset breast cancer (age < or = 40) composed 29.3% of all patients. The five-year survival rate of all patients was 80.4% (95% confidence interval [CI], 76.2-84.6%). The five-year overall survival rate for stage 0 was 95.7% (95% CI, 87.3-100%), stage I, 93.9% (95% CI, 88.9-98.9%), stage II, 88.5% (95% CI, 82.0-95.1%), stage III, 65.0% (95% CI, 54.0-75.9%), and stage IV, 18.5% (95% CI, 3.4-33.7%). Multivariate analysis of primary operable breast cancer revealed that axillary lymph node involvement, high nuclear grade and early-onset breast cancer (age < or = 40) were poor prognostic factors. The early-onset breast cancer had a more aggressive clinical behavior than that of the older age group, their five-year disease-free survival rates for stage I, stage II and stage III diseases being only 64.7%, 66.5%, and 43.3%, respectively. In these patients the only meaningful prognostic factor was extensive axillary lymph node metastasis (> or = 10). In summary, breast cancer patients in Taiwan tend to be younger than their counterpart in western countries. The early-onset breast cancer had poorer prognostic features for all stages comparing to the older age group. Standard pathologic factors are not good predictors of their outcome. For these patients new biologic markers need to be sought to distinguish between high and low risk and the treatment strategy for them should be guided by the aggressive characteristics of the disease.

Adult↗

PubMed2000

Simultaneous single-cell detection of two mutations for cystic fibrosis.

PURPOSE: A single-cell diagnosis procedure using polymerase chain reaction (PCR) technology was developed to simultaneously detect two cystic fibrosis (CF) mutations (DF-508, W1282X). METHODS: The reported test procedures made use of specific cell lines (lymphoblasts, fibroblasts) of known CF mutation status to determine the efficiency of signal generation and prevalence of allele dropout (ADO) during amplification. RESULTS: Using cells carrying the DF-508 mutation, the PCR signal efficiency for the affected homozygous, normal homozygous, and carrier heterozygote cell populations were 91%, 81%, and 92%, respectively. The total combined PCR efficiency was 87.7% and the ADO rate was 5.7%. For W1282X carrier heterozygote cells, the PCR signal efficiency was 82.0% and the ADO rate was 8.7%. CONCLUSIONS: Methods have been developed to detect two common mutations simultaneously for CF in single-cell assays. The high signal efficiencies and low ADO rates obtained in these tests allow those embryos from couples wishing to avert the transmission of this serious genetic disease to their offspring to be screened by preimplantation genetic diagnosis.

Cell Line↗

PubMed2000

Primer system for single cell detection of double mutation for Tay-Sachs disease.

PURPOSE: Nearly 100% of infantile Tay-Sachs disease is produced by two mutations occurring in the alpha chain of the lysosomal enzyme beta-N-acetylhexosaminidase (HEXA) in the Ashkenazi Jewish population. Although others have described primer systems used to amplify both sites simultaneously, few discuss the allele dropout problems inherent in this test. Our goal was to construct a more robust test enabling stronger signal generation for single cell preimplantation genetic diagnosis and to investigate the occurrence of allele dropout. METHODS: New nested primers were designed to optimize detection of both major Tay-Sachs mutations. Four hundred fifty-seven single cells, including normal cells and those carrying mutations of either the 4bp insertion exon 11 or splice-site intron 12 defects, were used to screen a new primer system. RESULTS: Based on PCR amplified product analysis, total efficiency of amplification was 85.3%, (390/457). The allele dropout rate for the 4bp insertion mutation in exon 11 and splice-site mutation in intron 12 was 4.8% and 5.8%, respectively. CONCLUSIONS: Multiple mutation detection and analysis within the Tay-Sachs disease gene (HEXA) is possible using single cells for clinical preimplantation genetic diagnosis. Alternative PCR primers and conditions offer various methods for developing systems compatible to specific program requirements.

Base Sequence↗

PubMed2000

Blood glutathione and cysteine changes in cardiovascular disease.

The need to investigate aminothiols such as glutathione (GSH), cysteine (Cys), and homocysteine (Hcy) in blood is stimulated by the current interest in hyperhomocysteinemia as a risk factor for atherosclerosis. Our current goal was to determine whether various cardiovascular (CV) diseases altered levels of GSH and Cys in blood and the relationships between these two thiols. Blood samples from 96 patients with atherosclerosis and other CV diseases were analyzed and compared with those from 33 control subjects. In CV patients, GSH levels were normal, but free plasma Cys was significantly higher (P < .0001). In patients with atherosclerosis, bound plasma Cys was 21% higher than that in control subjects (P < .0001), and in patients with other CV diseases it was 14% higher (P = .023). Also, in patients with CV diseases, correlations of free GSH with free Cys (P < .007) and total GSH and Cys with age (P < .04) differed from that in control subjects. There were no differences related to functional disability or duration of disease. A key finding was that these abnormal levels of plasma Cys occurred in both atherosclerotic and non-atherosclerotic CV diseases. These results indicate that high levels of oxidized and bound Cys in CV patients create an oxidative environment that may increase susceptibility to vascular damage.

Adult↗

PubMed2000

Blood glutathione decreases in chronic diseases.

Previously a high blood glutathione level was correlated with long life span in the mouse and rat and in healthy elderly human beings. This raised the question of whether low glutathione levels occur in unhealthy subjects. To this end, 74 consecutive patients newly admitted to the hospital, with ages ranging from 21 to 89 years and diagnosed with chronic diseases, were studied along with 32 healthy control subjects. Blood samples were analyzed for reduced (GSH) and oxidized (GSSG) glutathione with a high-performance liquid chromatography-dual electrochemical method. The data were integrated with the clinical diagnoses and statistically analyzed. Marked total glutathione decreases from the control levels occurred in over 36% of the patients with chronic diseases including cancer and genitourinary, gastrointestinal, cardiovascular, and musculoskeletal diseases (P < .001). The deficit was due to low GSH concentrations and not to GSSG, which was the same as that in the control subjects. The conclusion is that a decrease in GSH is a risk factor for chronic diseases that may be used to monitor the severity and progress of the diseases. Future work is necessary to elucidate the mechanism of action.

Adult↗

PubMed2000

Prediction of programmed-temperature retention values of naphthas by artificial neural networks.

It is proposed for the first time a method of prediction of the programmed-temperature retention times of components of naphthas in capillary gas chromatography using artificial neural networks. People are used to predict the programmed-temperature retention time using many formulas such as the integral formula, which requires that four parameters must be determined by calculation or experiments. However the results obtained by the formula are not so good to meet the demand of industry. In order to predict retention time accurately and conveniently, artificial neural networks using five-fold cross-validation and leave-20%-out methods have been applied. Only two parameters: density and isothermal retention index were used as input vectors. The average RMS error for predicted values of five different networks was 0.18, whereas the RMS error of predictions by the integral formula was 0.69. Obviously, the predictions by neural networks were much better than predictions by the formula, and neural networks need fewer parameters than the formula. So neural networks can successfully and conveniently solve the problem of predictions of programmed-temperature retention times, and provide useful data for analysis of naphthas in petrochemical industry.

Chemical Industry↗

PubMed2000

Synthesis and biological evaluation of 1,3-oxathiolane 5-azapyrimidine, 6-azapyrimidine, and fluorosubstituted 3-deazapyrimidine nucleosides.

(2R,5S)-5-Amino-2-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]- 1,2,4-triazine-3(2H)-one (8) and (2R,5R)-5-amino-2-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]-1,2,4-tr iazine-3(2H)-one (9) have been synthesized via a multi-step procedure from 6-azauridine. (2R,5S)-4-Amino-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]-1,3, 5-triazine-2(1H)-one (11) and (2R,5R)-4-amino-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]- 1,3,5-triazine-2(1H)-one (12), and the fluorosubstituted 3-deazanucleosides (19-24) have been synthesized by the transglycosylation of (2R,5S)-1-[2-[[(tert-butyldiphenylsilyl) oxy]methyl]-1,3-oxathiolan-5-yl] cytosine (2) with silylated 5-azacytosine and the corresponding silylated fluorosubstituted 3-deazacytosines, respectively, in the presence of trimethylsilyl trifluoromethanesulfonate as the catalyst in anhydrous dichloroethane, followed by deprotection of the blocking groups. These compounds were tested in vitro for cytotoxicity against L1210, B16F10, and CCRF-CEM tumor cell lines and for antiviral activity against HIV-1 and HBV.

Animals↗

PubMed2000

Manganese administration induces the increased production of dopamine sulfate and depletion of dopamine in Sprague-Dawley rats.

Sprague-Dawley rats were used as an experimental model for investigating the effects of manganese poisoning on the serum levels of unsulfated and sulfated forms of dopamine and its biosynthetic precursors, L-Dopa and L-p-tyrosine. Groups of rats were treated daily with Mn(2+) (20 mg or 40 mg; in the form of MnSO(4)) or Na(+) (20 mg; in the form of Na(2)SO(4)). High performance liquid chromatography (HPLC) analysis of the serum samples taken after a 50-day experimental period revealed that the serum level of dopamine sulfate increased by more than 10 times compared with untreated control rats or rats treated with sodium sulfate. In contrast, there was a dramatic decrease (by as much as 4.8 times) in the serum level of unsulfated dopamine in manganese-treated rats. The serum levels of L-Dopa sulfate and L-p-tyrosine sulfate were also markedly elevated, although not as much as those of dopamine sulfate. Meanwhile, the serum levels of unsulfated L-Dopa and L-p-tyrosine showed no dramatic changes. Atomic absorption spectrophotometric analysis revealed in general an accumulation of manganese in the four organ samples taken from manganese-treated rats. Compared with liver, heart, and kidney, the highest degree of manganese accumulation in manganese-treated rats appeared to be in brain. These results together suggested a role for manganese in stimulating the dopamine-sulfating sulfotransferases in brain, thereby leading to the depletion of dopamine in vivo.

Administration, Oral↗

PubMed2000

Adjuvant sequential chemotherapy with doxorubicin plus cyclophosphamide, methotrexate, and fluorouracil (ACMF) with concurrent radiotherapy in resectable advanced breast cancer.

Doxorubicin (Adriamycin) is an anthracycline effective in breast cancer. Despite a worldwide acceptance of Adriamycin in the adjuvant chemotherapy to maximize the survival benefit in the higher risk patients with breast cancer with promising results, oncologists in general do not favorably consider anthracyclines in the adjuvant treatment setting because of concern about the acute and chronic drug-related toxicity. For high-risk patients with breast cancer with more than three positive axillary lymph nodes, this series adopted a modified sequential regimen of ACMF first with Adriamycin (A) as a single agent in 3-weekly administration for three courses, and then a combination of cyclophosphamide, methotrexate, fluorouracil (CMF) every 3 to 4 weeks for six courses given in an outpatient setting concurrent with radiation therapy as an adjuvant treatment. A total of 56 patients underwent modified radical mastectomy and 3 others breast conservation surgery for their invasive breast cancer. Forty-seven (84%) patients completed the intended adjuvant treatment and 1 patient died of infection from treatment-related neutropenia. As a whole, the 3-year overall survival and disease-free survival rates of 56 patients analyzed were 82.3% and 64.4%, respectively. In this high-risk group, patients with four to nine positive nodes showed a slightly better trend of survival than those with 10 or more positive nodes without reaching statistically significant difference (36-month overall survival: 90.9% vs. 72.5%, p = 0.06; disease-free survival: 78.7% vs. 47.8%, p = 0.38). In this entire group of patients, locoregional recurrence was absent. A total of 55 episodes of grade III and IV hematologic toxicity were observed, with only one death from neutropenic sepsis. This modified ACMF regimen offers a good survival rate in breast cancer patients with more than three positive axillary lymph nodes. When these patients are carefully managed, the morbidity and mortality related to the treatment are low.

Adult↗

PubMed2000

Effect of recombinant human platelet-activating factor-acetylhydrolase on allergen-induced asthmatic responses.

Platelet-activating factor (PAF) is a potent lipid mediator associated with key features of asthma such as airway constriction, eosinophil infiltration, edema, and mucus accumulation. Regulation of PAF occurs primarily through degradation to biologically inactive lyso-PAF by cellular and secreted PAF-acetylhydrolase (PAF-AH). We evaluated the effect of human recombinant PAF-AH (rPAF-AH) on the dual phase asthmatic response in atopic subjects with mild asthma. Effects on induced sputum cell counts and differentials, eosinophilic cationic protein (ECP), and tryptase were evaluated. Enrolled subjects demonstrated a positive skin test and a dual asthmatic response to allergen inhalation challenge. Fourteen subjects received rPAF-AH (1 mg/kg) or placebo intravenously in a randomized, double blind, placebo-controlled, two-period crossover study. Treatment with rPAF-AH did not significantly reduce either the early- or late-asthmatic response. Sputum eosinophil cell counts were not affected by treatment, but there was a trend toward a reduction in sputum neutrophils. No significant change in sputum ECP and tryptase was observed between rPAF-AH and placebo. Thus, at the dose studied, the unique anti-PAF agent rPAF-AH demonstrated no significant effect on the allergen-induced dual-phase asthmatic response.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed2000

Locoregional recurrence in patients with one to three positive axillary nodes after mastectomy without adjuvant radiotherapy.

PURPOSE: To retrospectively assess the risk of locoregional recurrence (LRR) and analyze the prognostic factors of this pattern of failure in patients with breast cancer and one to three positive axillary lymph nodes treated with modified radical mastectomy (MRM) without adjuvant radiotherapy. METHODS: From April 1991 through December 1997, 649 patients received a diagnosis of invasive breast cancer, and 545 were treated with MRM. Eighty-one of these patients who were found to have one to three positive axillary nodes and had a minimum follow-up of 2 years were included in this study. None of the 81 patients received adjuvant radiation therapy after mastectomy; 43 patients received adjuvant chemotherapy; and 60 patients received adjuvant hormone therapy. The median duration of follow-up was 39 months. RESULTS: Thirteen patients had LRR during follow-up, all within 2 years after mastectomy. The 3-year LRR rate was 14%. The 3-year rates of distant metastasis for patients with and without LRR were 48% and 14% (p = 0.03), respectively. The 3-year survival rates for patients with and without LRR were 73% and 87% (p = 0.01), respectively. In univariate analysis, age (p = 0.01), estrogen receptor (ER) status (p = 0.02), and the addition of hormone therapy (p < 0.001) were significant risk factors for LRR; in multivariate analysis, negative ER status (p = 0.02) was the only statistically significant risk factor. The 3-year LRR rates for ER-negative patients and those with positive or unknown ER status were 31% and 11%, respectively. CONCLUSIONS: LRR after mastectomy is a substantial clinical problem, despite the use of adjuvant chemotherapy and/or hormone therapy. Further randomized trials of postmastectomy radiotherapy for patients with one to three positive axillary nodes and specific risk factors are urgently needed to determine its potential benefit in locoregional control and survival, especially for young and ER-negative patients.

Adult↗

PubMed1999

Involvement of cyclin-dependent kinase activities in CD437-induced apoptosis.

A novel synthetic retinoid, 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437), is a selective ligand of the RARgamma nuclear receptor. We examined the in vitro effects of CD437 and found that CD437 induces S phase arrest within 24 to 48 h, followed by cell death, in the p53-negative Hep3B and the p53-positive HepG2 human hepatoma cell lines. Based on observations of cellular and nuclear fragmentation, chromatin condensation, and DNA fragmentation, the CD437-mediated cell-killing effect appears to be due to apoptosis. On morphological examination, a number of CD437-treated cells were found to have increased 5- to 10-fold in size and persisted as single giant cells without cell division, while the remainder underwent nuclear division (multiple nuclei) but were unable to complete cytokinesis, and finally all died by apoptosis. In HepG2 cells that possessed wild-type p53, CD437-induced S phase arrest and apoptosis were accompanied by the up-regulation of cyclin A, cyclin B, p53, p21(CIP1/Waf1), Bad, and Bcl-Xs proteins and by a decrease in Bcl-2 protein levels. In Hep3B cells, CD437-mediated S phase arrest and apoptosis were also associated with a concomitant up-regulation of cyclin A, cyclin B, Bad, and Bcl-Xs. However, Hep3B cells did not express p53 or Bcl-2 messages. Olomoucine and roscovitine, the potent p34(cdc2) and CDK2 inhibitors, effectively blocked CD437-mediated cyclin A- and B-dependent kinase activation and prevented CD437-induced cell death. Furthermore, antisense oligonucleotide complementary to cyclin A and B mRNA significantly rescued CD437-induced apoptosis. These findings suggest that activation of cyclin A- and B-dependent kinases is a critical determinant of apoptotic death mediated by CD437.

Antineoplastic Agents↗

PubMed1999

Computer-aided development of a high-performance liquid chromatographic method for the determination of hydroxyanthraquinone derivatives in Chinese herb medicine rhubarb.

With computer simulation predicting separation in reversed-phase gradient elution, a method to separate and determine five hydroxyanthraquinone derivatives having a wide range of polarity in extract of Chinese herbal medicine rhubarb has been developed. The software DryLab was used to model the retention behavior of the compounds as a function of gradient conditions, based on data from two scouting gradient runs. Under the optimized conditions, i.e. column, Zorbax RX-C18, 5 microm, 15x0.46 cm; solvent A, 36 mM triethylamine phosphate (TEAP), pH=2.5; solvent B, ACN; gradient, 36/36/80/80% B at 0/5.5/20.5/25.5 min; flow-rate, 1.00 ml/min; temperature, ambient, the method was successfully applied to monitor the quality of rhubarb from different sources. The effect of sample preparation procedures on extraction efficiency was also examined.

Anthraquinones↗