Biomedical subjects

J S Wei

Publications and source records attributed to J S Wei.

At least 19 recordsLinked to original sources

PubMed2001

Coronary smooth muscle differentiation from proepicardial cells requires rhoA-mediated actin reorganization and p160 rho-kinase activity.

We recently reported that the first detectable expression of SMC-specific proteins during coronary smooth muscle cell (CoSMC) differentiation from isolated proepicardial cells was restricted to cells undergoing epithelial-to-mesenchymal transformation (EMT). The objectives of this study were to examine more closely the relation between actin cytoskeletal rearrangements and serum response factor (SRF)-dependent transcription, and to specifically test whether rhoA-GTPase signaling is required for CoSMC differentiation. We report here that PDGF-BB stimulates EMT and promotes SRF-dependent expression of SMC marker genes calponin, SM22alpha, and SMgamma(actin) (SMgammaA) in proepicardial cells. C3 exoenzyme or rhoGDI, inhibitors of rhoA signaling, blocked PDGF-BB-induced EMT, prevented actin reorganization into stress fibers, and inhibited CoSMC differentiation. Incubation with the selective p160 rho-kinase (p160RhoK) inhibitor Y27632 (RKI) blocked EMT, prevented the appearance of calponin and SMgammaA-positive cells, and abolished expression and nuclear localization of SRF. To test the role of RhoK signaling for CoSMC differentiation in vivo, quail proepicardial organs (PEOs) were pretreated with RKI or vehicle and then grafted into age-matched host chick embryos to produce a chimeric epicardium. The ability of grafted cells to participate in coronary vessel formation was monitored by staining with antibodies for quail cell nuclear antigen and SMC marker proteins. Proepicardial cells pretreated with RKI failed to form CoSMCs in vivo. Time course studies traced this deficiency to a failure of epicardial-derived mesenchymal cells to migrate into or survive within the myocardium. In summary, these data point to important roles for rhoA-RhoK signaling in molecular pathways controlling cytoskeletal reorganization, SRF-dependent transcription, and cell survival that are required to produce CoSMCs from proepicardial cells.

Actins↗

PubMed2001

Homocysteine thiolactone induces apoptotic DNA damage mediated by increased intracellular hydrogen peroxide and caspase 3 activation in HL-60 cells.

The cytotoxicity of homocysteine derivatives on chromosomal damage in somatic cells is not well established. The present study used reactive homocysteine derivative of homocysteine thiolactone (Hcy) to investigate its causal effect on apoptotic DNA injury in human promyeloid HL-60 cells. Our results demonstrated that Hcy induced cell death and features of apoptosis including increased phosphotidylserine exposure on the membrane surface, increased apoptotic cells with hypoploid DNA contents, and internucleosomal DNA fragmentation, all of which occurred in a time- and concentration-dependent manner. Hcy treatment also significantly increased intracellular reactive oxygen species H2O2, which coincided with the elimination of caspase 3 proenzyme levels and increased caspase 3 activity at the time of the appearance of apoptotic DNA fragmentation. Preincubation of Hcy-treated HL-60 cells with catalase completely scavenged intracellular H2O2, thus inhibiting caspase 3 activity and protecting cells from apoptotic DNA damage. In contrast, superoxide dismutase failed to inhibit Hcy-induced DNA damage. Taken together, these results demonstrate that Hcy exerted its genotoxic effects on HL-60 cells through an apoptotic pathway, which is mediated by the activation of caspase 3 activity induced by an increase in intracellular hydrogen peroxide.

Apoptosis↗

PubMed2001

Glioma cell motility is associated with reduced transcription of proapoptotic and proliferation genes: a cDNA microarray analysis.

Microarray analysis of complementary DNA (cDNA) allows large-scale, comparative, gene expression profiling of two different cell populations. This approach has the potential for elucidating the primary transcription events and genetic cascades responsible for increased glioma cell motility in vitro and invasion in vivo. These genetic determinants could become therapeutic targets. We compared cDNA populations of a glioma cell line (G112) exposed or not to a motility-inducing substrate of cell-derived extracellular matrix (ECM) proteins using two sets of cDNA microarrays of 5,700 and 7,000 gene sequences. The data were analyzed considering the level and consistency of differential expression (outliers) and whether genes involved in pathways of motility, apoptosis, and proliferation were differentially expressed when the motility behavior was engaged. Validation of differential expression of selected genes was performed on additional cell lines and human glioblastoma tissue using quantitative RT-PCR. Some genes involved in cell motility, like tenascin C, neuropilin 2, GAP43, PARG1 (an inhibitor of Rho), PLCy, and CD44, were over expressed; other genes, like adducin 3y and integrins, were down regulated in migrating cells. Many key cell cycle components, like cyclin A and B, and proliferation markers, like PCNA, were strongly down regulated on ECM. Interestingly, genes involved in apoptotic cascades, like Bcl-2 and effector caspases, were differentially expressed, suggesting the global down regulation of proapoptotic components in cells exposed to cell-derived ECM. Overall, our findings indicate a reduced proliferative and apoptotic activity of migrating cells. cDNA microarray analysis has the potential for uncovering genes linking the phenotypic aspects of motility, proliferation, and apoptosis.

Apoptosis↗

PubMed2001

Classification and diagnostic prediction of cancers using gene expression profiling and artificial neural networks.

The purpose of this study was to develop a method of classifying cancers to specific diagnostic categories based on their gene expression signatures using artificial neural networks (ANNs). We trained the ANNs using the small, round blue-cell tumors (SRBCTs) as a model. These cancers belong to four distinct diagnostic categories and often present diagnostic dilemmas in clinical practice. The ANNs correctly classified all samples and identified the genes most relevant to the classification. Expression of several of these genes has been reported in SRBCTs, but most have not been associated with these cancers. To test the ability of the trained ANN models to recognize SRBCTs, we analyzed additional blinded samples that were not previously used for the training procedure, and correctly classified them in all cases. This study demonstrates the potential applications of these methods for tumor diagnosis and the identification of candidate targets for therapy.

Burkitt Lymphoma↗

PubMed1999

Folate deficiency induces a cell cycle-specific apoptosis in HepG2 cells.

The human hepatoma HepG2 cell line was chosen as a representative of solid tissue-derived cell systems in which folate metabolism and apoptosis induction have not been thoroughly investigated. HepG2 cells were cultivated in the control or folate-deficient media (control media lacking of folate, glycine, thymidine and hypoxanthine) for 4 wk. This resulted in a decrease in intracellular folate levels to 32% of the control within 1 wk, which was followed by growth arrest and greater cell death rates. These disturbances of folate deficiency coincided with apoptotic induction, as characteristically shown by nucleosomal DNA fragmentation of 180-200 base pair multimers, nuclear chromatin condensation and positive terminal transferase-mediated dUTP nick end labeling assay. Apoptosis coincided with an accumulation of cells in S-phase, a subsequent G2/M phase block and a significant increase in mean protein content as evaluated by flow cytometric analyses employing a double-staining method. The growth and cell cycle arrest under folate-deficient conditions was independent of a change of p53 expression as measured by an enzyme-linked immunosorbent assay. Supplementation of 2 micromol/L folate normalized cell cycles and diminished DNA fragmentation. Taken together, these data indicate that HepG2 cells cultivated in folate-deficient medium have a low folate concentration, decreased growth and viability, and increased apoptotic propensity. This occurrence of apoptosis was associated with a cell cycle-specific mechanism and independent of p53-mediated pathway.

Apoptosis↗

PubMed1998

Detection of endogenous digitalis-like immunoreactive factors in human blood.

Digitalis-like immunoreactive factors (DLIF) are special types of steroids with lactone rings in their structures. Clinically, this type of compound can be used as medicine for heart failure; thus, the elevated endogenous DLIF found under certain pathological conditions are interferent substances in digoxin immunoassay. Endogenous DLIF with biological and immunological properties similar to cardiotonic drugs, such as digoxin, have been found in several tissues and body fluids of animals and humans. Since these endogenous Na+, K(+)-ATPase inhibitors can be considered hormones in nature, immunoassays must be selected detection of them to achieve the required sensitivity and specificity. In this study, we used three sets of in-house formulated immunoassays for DLIF and ouabain-like factors (OLF) detection. Using a polyclonal antibody-based ouabain enzyme immunoassay, the mean +/- S.E.M. of OLF in the sera of 10 healthy individuals were determined to be (9.1 +/- 0.9) x 10(-11) M. Using a monoclonal antibody-based ouabain enzyme immunoassay, the mean +/- S.E.M of OLF in the sera of 10 healthy individuals was (8.2 +/- 1.2) x 10(-11) M while using a antibody fragment Fab-based enzyme immunoassay for digoxin, the mean +/- S.E.M of DLIF in 11 healthy individuals was (4.0 +/- 1.2) x 10(-10) M. In conclusion, our immunological data indicate that DLIFs are normal constituents of human blood. Although DLIF is the major component, coexistence of OLF with DLIF in healthy individuals can not be excluded.

Animals↗

PubMed1997

Hemin-induced membrane sulfhydryl oxidation: possible involvement of thiyl radicals.

Sublytic levels (microM) of hemin destabilized RBC membrane as indicated by ghost fragmentation pattern using a laser viscodiffractometer. Furthermore, electron microscopic study shows that 5 microM of hemin induced echinocytic transformation whereas higher hemin concentration (40 microM) induced spherocytic transformation. In addition, hemin oxidized sulfhydryl groups in a dose dependent fashion and Electron Spin Resonance study suggests that such oxidation may involve a thiyl radical. Moreover, sulfhydryl compounds enhanced hemin-induced lipid peroxidation. Desferroxamine could prevent hemin-induced sulfhydryl oxidation as well as hemin-induced decrease in membrane stability. In contrast, vitamin E could effectively prevent hemin-induced lipid peroxidation but could not prevent hemin-mediated membrane destabilization.

Deferoxamine↗

PubMed1996

Enhanced vesiculation exacerbates complement-dependent hemolysis in glucose-6-phosphate dehydrogenase deficient red blood cells.

Glucose-6-phosphate dehydrogenase (G6PD) deficient red blood cells (RBCs) are known to be more susceptible to oxidant-induced hemolysis. Erythrocytes from G6PD-deficient individuals are significantly more susceptible to Ca(2+)-induced vesiculation than normal control cells. The enhanced susceptibility of G6PD-deficient RBCs to Ca(2+)-induced vesiculation is not due to ATP depletion. The remnant G6PD-deficient RBCs following vesiculation are more sensitive to complement-mediated hemolysis than control normal RBCs. A strong positive correlation exists between the level of Ca(2+)-induced vesiculation and the extent of complement mediated hemolysis.

Calcium↗

PubMed1996

Purification and characterization of endogenous digoxin-like immunoreactive factors in chicken blood.

Studies have been performed to determine whether an endogenous material capable of binding to digoxin antibodies is present in the chicken plasma. In the blood of 12 chickens without feed control, endogenous digoxin-like immunoreactive factors (DLIF) binding of digoxin antibodies in enzyme immunoassays amounted to 866 / 302 pg digoxin equivalents/mL of plasma (mean +/- SEM). Immunoreactivity of DLIF increased to 1848***331 pg/mL with a double value of control after boiling and acid pretreating the plasma. The major purification steps employed in this report were gel filtration column chromatography, high performance liquid chromatography (HPLC) and isoelectric focusing (IEF). Using HPLC for the separation, at least 10 chicken DLIFs with different molecular weight (MW) have been found. The MW of the smallest is 300 daltons (Da) while the largest is 100 kDa. The value of the isoelectric point of the most abundant type of DLIF from untreated chicken plasma is 6.3 as determined by IEF. The partially purified DLIF inhibits Na+, K(+)-ATPase from a porcine cerebral cortex as well as three human red blood cell membrane preparations in a dose-response fashion.

Animals↗

PubMed1996

Correlation of membrane lipid peroxidation with oxidation of hemoglobin variants: possibly related to the rates of hemin release.

Experiments were performed to delineate the biochemical mechanism of hemoglobin (Hb)-catalyzed lipid peroxidation in human red blood cells (RBCs). Using a modified Langmuir trough lipid monolayer technique, we found that oxidized Hb induced an increase in lipid monolayer surface pressure, suggesting that oxidized Hb readily releases its heme moiety into the lipid monolayer. To confirm our interpretation that oxidized Hb readily releases its heme moiety, we monitored the fluorescence of Hb tryptophan upon oxidation of Hb. We found an increase in Hb fluorescence in the aqueous phase of our monolayer system after the addition of H2O2. The increase in fluorescence should reflect the departure of heme from globin due to a decrease in fluorescent quenching effect by the heme moiety. The rate of increase in lipid monolayer surface pressure upon Hb oxidation differed from Hb to Hb with an order of Hb E > F > S > A. The ability of various Hbs to affect lipid peroxidation in the RBC membrane, as monitored by the parinaric acid oxidation technique, followed this same order. In addition, hemin was shown to be a more potent catalyst of lipid peroxidation in RBC membrane than nonheme irons.

Adult↗

PubMed1994

Detection of a novel lactate dehydrogenase isozyme and an apparent differentiation-associated shift in isozyme profile in hepatoma cell lines.

A hitherto unreported lactate dehydrogenase (LD) isoenzyme, which migrates electrophoretically to the relative position between LD2 and LD3 has been identified in the electropheratogram in 7 of 7 (100%) cultured hepatoma cell lines with various degrees of differentiation and is thus given the name LD2-3. LD2-3 seems to be specific for hepatoma cells because this atypical isoenzyme can not be detected in other tumor cell lines. In addition, the hepatoma cell lines also show a distinct pattern of LD isoenzyme and the isoenzyme pattern varies with the degree of differentiation. Hence, the expression pattern of LD isoenzyme phenotypes may provide a good marker for the investigation of human hepatoma cell differentiation.

Carcinoma, Hepatocellular↗

PubMed1994

Enhanced susceptibility of erythrocytes deficient in glucose-6-phosphate dehydrogenase to alloxan/glutathione-induced decrease in red cell deformability.

It has been hypothesized that enhanced oxidant sensitivity of glucose-6-phosphate dehydrogenase (G6PD) deficient red cells(RBCs) is the underlying mechanism for drug- or chemical-induced hemolytic crises in G6PD-deficiency. To further test this hypothesis, we used an alloxan-glutathione system to mimic oxidative stress and see how oxidative damage might affect RBC deformability. RBC deformability, a major determinant of RBC survival in vivo, was monitored by a laser viscodiffractometer. Under our experimental conditions, GSH alone had very little effect on the deformability of either normal or G6PD-deficient RBCs. In contrast, alloxan alone induced a small but significant decrease in the deformability of either normal or G6PD-deficient RBCs. Interestingly, alloxan and GSH together induced a further decrease in the deformability of either normal or G6PD-deficient RBCs. The decrease in deformability in G6PD-deficient RBCs was much more profound than in normal RBCs. In addition, an alloxan-vitamin C system produced a similar deleterious effect on RBC deformability as that produced by the alloxan-GSH system. Appreciable amount of hydroxyl radicals was generated by both alloxan-GSH and alloxan-vitamin C systems as evidenced by the production of hydroxylated products of salicylate which was used as a radical trap. Moreover, salicylate could ameliorate the deleterious effect of the alloxan system on the deformability of RBCs. Taken together, our results demonstrated that G6PD-deficient RBCs were particularly susceptible to oxidant-induced damage leading to a dramatic decrease in their deformability and thus provided strong support for the hypothesis that enhanced oxidant sensitivity of G6PD-deficient RBCs is the underlying mechanism for accelerated destruction of these RBCs in vivo.

Alloxan↗

PubMed1994

Sequential liver and bone biochemical changes in hyperthyroidism: prospective controlled follow-up study.

OBJECTIVE: To reexamine the prevalence and sequential changes of liver and bone biochemical abnormalities in patients with hyperthyroidism. METHODS: A consecutive series of 95 patients with hyperthyroidism and 66 controls with euthyroid goiter seen during same period were studied. The patients were treated with propylthiouracil (PTU) 300 mg/day for 2 months, followed by 100-150 mg/day for 3 months and a subsequent maintenance dose of 100 mg/day. Serum aspartate amino-transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT), bilirubin, ALP isoenzymes, and hepatitis markers were studied before therapy and at 2 and 5 months after PTU therapy was begun. RESULTS: Seventy-two [75.8%, confidence interval (CI) 67.2-84.4%] of the 95 patients had at least one biochemical abnormality. AST, ALT, ALP, GGT, and bilirubin were elevated in 27.4%, 36.8%, 64.2%, 16.8%, and 5.3%, respectively. Of the 34 patients with ALT elevation, 62% showed gradual normalization of ALT, whereas 38% (CI 21.9-54.5%) showed transient, asymptomatic, but significant (p < 0.025) further elevation of ALT during PTU therapy. Overt hepatitis developed in one patient. None of these changes was due to hepatitis A, B, C, or delta virus infection or autoimmune hepatitis. Changes of serum GGT parallel those of ALT. In contrast, serum ALP (primarily bone isoenzyme) rose significantly (p < 0.01) as T4 and T3 levels declined at 2 months after therapy. CONCLUSIONS: The results suggest that hyperthyroidism is often associated with abnormal biochemical tests, particularly ALP elevation, and thus may pose diagnostic confusion. The increase of bone isoenzyme accounts for the elevations in total ALP level before and during therapy. Serum ALT and GGT abnormalities usually subside during PTU therapy, but transient asymptomatic PTU hepatotoxicity occurs in one-third of the patients. Discontinuation of PTU is not required unless overt hepatitis develops.

Adolescent↗

PubMed1993

Alkaline phosphatase activity during sphinganine potentiation of retinoic acid-induced differentiation of human promyelocytic leukemia cell line, HL-60.

Sphinganine (SP) pre-treatment potentiated the retinoic acid (RA)-induced (4-96h exposures) differentiation and increase of alkaline phosphatase (ALP) activity. A higher percentage of SP pre-treated cells in RA exposures resembled mature myelocytes or granulocytes; greater increase in ALP activity was observed. In cells exposed to RA alone for only a period of 24h, the ALP activity could still increase and reach a similar maximum ALP activity (8.5-10.0 units/mg protein) at 48h as it was under continuous RA treatment. In all cells with longer exposures (24-96h) to RA, SP pre-treatment increased ALP activity to more or less the same higher maximum (14.0-15.5 units/mg protein). SP, added 24h before or concomitantly, but not 24 nor 48h after the addition of RA, could potentiate the RA-induced differentiation and increase of ALP activity.

Alkaline Phosphatase↗

PubMed1993

High-molecular-mass alkaline phosphatase as a tumor marker for colorectal cancer: comparison of two test methods.

We measured high-molecular-mass alkaline phosphatase (HiMwALP) in serum samples from patients with colorectal cancer by polyacrylamide gel electrophoresis (PAGE) and by column chromatography on diethylaminoethyl (DEAE)-cellulose. Determination of carcinoembryonic antigen (CEA) by an enzyme immunoassay, a frequently used cancer assessment method, was used for comparison. We studied patients with primary colorectal cancer (n = 72), using others with hemorrhoids (n = 38) for a comparison group. HiMwALP activities twice those of pooled normal sera were adopted as cutoff values. The diagnostic sensitivity of the PAGE method for 72 colorectal cancer patients was 63% vs 36% for the DEAE method and 50% for the CEA method. The diagnostic specificities of the PAGE, DEAE, and CEA methods were 89%, 79%, and 95%, respectively. Using both HiMwALP (PAGE method) and CEA for the detection of primary colorectal cancer increased the sensitivity to 72% but decreased specificity to 87%.

Adult↗

PubMed1992

Alkaline phosphatase activity during differentiation of the human promyelocytic leukemia cell line, HL-60.

The differentiation of HL-60 promyelocytic cells toward mature myelocytic cells induced by retinoic acid (RA) was accompanied by a quantitative similar increase in alkaline phosphatase (ALP) activity. The potentiation of RA-induced differentiation and the enhancement of ALP activity by sphinganine seemed to correlate with each other. The combination of RA and sphinganine increased in parallel the percentage of mature cells and the ALP activities. Short exposures (4-8h) of HL-60 cells to RA promoted differentiation and ALP activity to a fraction (about 50%) of their maximums which were achieved in cells after 24h or longer RA exposure. Our results indicate that the key step for the induction of ALP activity and the differentiation by RA probably takes place within 24h of incubation.

Alkaline Phosphatase↗

PubMed1992

Metformin-induced lactic acidosis: report of a case.

Lactic acidosis associated with diabetic patients receiving metformin therapy is rare but may cause significant morbidity and mortality. In nearly all reported cases of metformin-associated lactic acidosis, contraindications to its use were noted, especially renal insufficiency. We describe a 59-year-old diabetic man treated with metformin for more than three years. During the third year of use, he experienced progressive renal function impairment, and during the final month of use, he became azotemic. He was maintained on continuous ambulatory peritoneal dialysis. Several days prior to admission, he suffered from epigastralgia, nausea and vomiting, followed by progressive dyspnea which was Kussmaul in nature. Profound hypotension developed and he sank progressively into a coma. Wide-anion gap metabolic acidosis without ketonemia was detected. His blood lactate level was elevated and metformin-induced lactic acidosis was substantiated. An elevated plasma metformin level of greater than 50 mg/mL was determined later by high-performance chromatography. Rigorous treatment including bicarbonate therapy, bicarbonate hemodialysis and vasoactive agents as well as supportive measures were provided. With a return of pH to normal, the hypotension resolved and his consciousness level slowly improved. Our patient survived this disastrous event, but some neurologic sequelae remained. In order to avoid this life-threatening metabolic disturbance, patients with any contraindications should not be prescribed metformin.

Acidosis, Lactic↗

PubMed1992

Apolipoprotein levels in normolipidemic non-insulin-dependent diabetes mellitus.

The purpose of this study was to examine the change in apolipoprotein and lipoprotein levels in patients with normolipidemic untreated non-insulin-dependent diabetes mellitus (NIDDM). Fifteen untreated, non-obese male NIDDM patients without hyperlipidemia were chosen, and 15 healthy subjects, matched for age, sex, body weight, alcohol consumption and cigarette smoking served as the control group. We observed that the concentrations of plasma total cholesterol (TC), triacylglycerol (TG) and very low density lipoprotein cholesterol (VLDL-C) were identical in both NIDDM and control groups. The levels of low-density lipoprotein cholesterol (LDL-C) were slightly increased in the diabetic group, but the difference did not reach statistical significance in our study. High-density lipoprotein cholesterol (HDL-C) was lower in the NIDDM group than in the controls. Significantly increased TC/HDL-C and LDL-C/HDL-C ratios were found in NIDDM patients compared with controls. The apolipoprotein A-I (apo A-I) and apolipoprotein A-II (apo A-II) levels were decreased in NIDDM patients, while the apolipoprotein B (apo B) level remained similar to that of the control subjects. The ratio of apo A-I/apo B was decreased significantly in the NIDDM group. Our results suggest that NIDDM patients are at higher risk of coronary heart disease, even if they remain normolipidemic.

Adult↗