Biomedical subjects

Z Yao

Publications and source records attributed to Z Yao.

At least 73 records · Page 4Linked to original sources

PubMed2000

Effect of 1,25(OH)2D3 on the growth and apoptosis of breast cancer cell line MCF-7.

OBJECTIVE: To study the effect of 1, 25-dihydroxyvitamin D3(1,25(OH)2D3) on the growth and apoptosis of breast cancer cell line MCF-7. METHODS: Cell number was determined using the MTT method. Flow cytometric analysis was performed on cell cycles, and the percentage of apoptosis was counted. Apoptotic cells were quantified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and bcl-2 protein expression was estimated with Western blotting. RESULTS: After incubation with 1,25(OH)2D3 10(-7) mol/L for 48 hours, MCF-7 cells exhibited significant growth in a dose- and time-dependent manner. Flow cytometric analysis indicated that cell numbers in G0/G1 increased along with increasing apoptotic peak and percentage. With microscope and electron microscope observation, characteristics of apoptosis such as typical apoptotic bodies were commonly found. TUNEL also showed that 1,25(OH)2D3 10(-8) mol/L and 10(-7) mol/L groups had significantly high apoptosis percentage than control group with dose-dependence on induction apoptosis. And Western blot showed that 1,25(OH)2D3 10(-8) mol/L could down-regulate bcl-2 protein and 10(-7) mol/L could almost block bcl-2 protein expression. CONCLUSIONS: 1,25(OH)2D3 can inhibit cell growth with G0/G1 arrest, enhance the proliferation inhibition action of adriamycin, and induce apoptosis which may result from the down-regulation of the anti-apoptotic bcl-2 protein.

Apoptosis↗

PubMed2000

Antifungal therapy for treatment of cryptococcal meningitis.

OBJECTIVE: To compare the curative effects of three different antifungal regimens in the treatment of cryptococcal meningitis. METHODS: Twenty-two patients were divided into 3 groups: Group I was given intravenous amphotericin B alone or combination with flucytosine therapy. Group II received intravenous fluconazole alone or combination with flucytosine. The treatment of Group III was divided into two steps, where the patients received intrathecal amphotericin B plus intravenous amphotericin B with or without intravenous fluconazole until the mycological culture of cerebrospinal fluid (CSF) turned negative, followed by oral fluconazole or itraconazole as maintenance therapy until direct microscopic examination of CSF showed negative once a week for three consecutive weeks. RESULTS: Of the twenty-two patients, 17 (77.3%) were cured, 2 (9.1%) improved, 3 (13.6%) died, and one (4.5%) relapsed. Of the 8 patients in Group I, 5 were cured, 2 improved, one died and one relapsed; Of the 4 patients in Group II, 2 were cured, and 2 died; All the 10 patients in Group III were cured without any recurrence. CONCLUSION: The two-step therapeutic regimen may be suited to the treatment of cryptococcal meningitis.

Adolescent↗

PubMed2000

99mTc-MIBI and 99mTc-MDP scintimammography for detecting breast carcinoma.

OBJECTIVE: To assess the value of scintimammography with both 99mTc-MIBI and 99mTc-MDP in detecting breast cancer. METHODS: A total of 35 women with clinical findings of suspicious breast lesions were studied with both 99mTc-MIBI and 99mTc-MDP scintimammography. All patients underwent surgery within one week and the final diagnostic results (histopathological) were obtained. RESULTS: Eighteen of 35 abnormalities of breast were pathologically confirmed as breast cancer and 17 as benigN lesions. In this group of patients studied, the sensitivity, specificity and accuracy of 99mTc-MIBI scintimammography were 77.8%, 88.2% and 82.9%, respectively and those of 99mTc-MDP scintimammography were 72.2%, 88.2% and 80.0%, respectively. There was no significant difference between 99mTc-MIBI and 99mTc-MDP scintimammography. CONCLUSION: This study showed the high diagnostic accuracy of both 99mTc-MIBI and 99mTc-MDP scintimammography in detecting breast cancer. Both can be used as non-invasively assess breast cancer invasiveness before surgery.

Adult↗

PubMed2000

99mTc-HL91 "hot spot" imaging of mice bearing human carcinoma by gamma camera and the effects of tumor necrosis on imaging.

OBJECTIVE: To evaluate the hypoxia-avid agent 99mTc-HL91 (99mTc labeled 4, 9-diaza-3, 3, 10, 10-tetramethyldodecan-2, 11-dione dioxime) as the tracer of tumor "hot spot" imaging and the influence of tumor necrosis on the image. METHODS: After injection of 99mTc-HL91, 6 nude mice bearing human breast cancer MCF-7 and 18 nude mice bearing human pancreatic adenocarcinoma were subjected to gamma camera imaging, postmortem analysis, and autoradiography and imaging of tumor sections. RESULTS: The image of tumor was identified 1 hour after injection of 99mTc-HL91. Images demonstrated gradually increased 99mTc-HL91 uptake in the tumor 1-12 hours after injection (P < 0.05-0.001). Six hours after injection, the radioactivity ratios of tumor to thorax and tumor to head were higher than 2.1. Six hours after injection, the radioactivity ratios of tumor to brain, muscle, blood, heart, lung and kidney in pancreatic adenocarcinoma bearing nude mice were 101.0 +/- 114.7, 30.0 +/- 30.3, 19.9 +/- 21.9, 14.4 +/- 15.1, 3.71 +/- 2.41 and 0.46 +/- 0.26, respectively, and the radioactivity ratios in breast cancer MCF-7 bearing nude mice were close to these figures. The radioactivity of non-necrotic tumor was 3.77 times that of necrotic tumor. However, the radioactivity ratios of tumor to liver, intestine and stomach were lower than 1.3. Autoradiographs and images of tumor sections showed that the radioactivity was higher in the region of solid tumor than in the necrotic region. CONCLUSION: 99mTc-HL91 via gamma camera positively identifies regional tumor in nude mice bearing human cancer. 99mTc-HL91 retention is lower in necrotic tumor than in non-necrotic tumor. The low radioactivity ratio of tumor to abdominal organs limits the application of 99mTc-HL91 in detecting abdominal tumors.

Adenocarcinoma↗

PubMed2000

[Effect of tamoxifen on apoptosis and drug resistance of breast cancer cells in vitro].

OBJECTIVE: To study the effect of estradiol (E2) and tamoxifen (TAM) on the apoptosis regulatory genes (bax, bcl-2) and mdr-1 in MCF-7 cells. METHODS: Immunohistochemistry, in situ hybridization were used to observe the changes in bax, bcl-2 and mdr-1 genes after treatment with E2 and TAM. RESULTS: E2 had ability to increase the expression of bcl-2 and mdr-1 but TAM decrease the expression of both. Synthetic bax oligodeoxynucleotide (ODN) was used as probe to perform in situ hybridization. It was shown that bax mRNA in MCF-7 cells was down-regulated by E2 and up-regulated by TAM. Significant correlation between bcl-2 and mdr-1 was observed after TAM treatment of MCF-7 cells (P < 0.05). CONCLUSION: TAM regulates cell apoptosis and inhibits development of drug-resistance of MCF-7 breast cancer.

Antineoplastic Agents, Hormonal↗

PubMed2000

[Etiological study on patients with seronegative viral hepatitis].

OBJECTIVE: To investigate the etiology of hepatitis patients who were seronegative for viral hepatitis A through E. METHODS: By using PCR, HBV DNA, HCV RNA, HEV RNA and HGV RNA were detected in sera of 104 patients with seronegative viral hepatitis. The partial nucleotide sequences of 2 HCV and 17 HEV isolates were analysed by direct sequencing. RESULTS: Among the 104 patients with seronegative viral hepatitis, the positive rates of HBV DNA, HCV RNA, HEV RNA and HGV RNA were 29.8%, 3.8%, 22.1% and 7.7%, respectively, with only 38 cases (36.6%) negative for the genome of all known hepatitis viruses. CONCLUSION: In addition to serological tests, the polymerase chain reaction of all known hepatitis viruses should be used to make the diagnosis of non-A - E hepatitis.

Base Sequence↗

PubMed2000

[Generation of cytotoxic T lymphocytes induced with HSP-PC70 derived from tumor cells].

OBJECTIVE: To investigate the killing effect of cytotoxic T lymphocytes (CTLs) induced with heat shock protein-peptide complexes (HSP-PC70) derived from tumor cells. METHODS: Cell culture, flow cytometric analysis, affinity chromatography for protein extraction and purification, SDS-PAGE, Western blotting, CTL induction and expansion, and LDH release were used. RESULTS: 63.5% of the HcaF cells expressed HSP-PC70 on their membrane by FCM analysis under physiological condition, and the expression was 75.5% of the stressed cells (P < 0.01). HcaF cells had high HSP70 expression and inducibility. The cytotoxic activity of the CTLs induced with HSP70 obtained by affinity chromatography from HcaF cells was 84.2%, 47.9% and 14.8% respectively at E/T ratio of 50 : 1, 25 : 1 and 12.5 : 1. The CTLs were CD8 positive T cells. All mice which received CTL injection got long period survival (over 90 days, P < 0.01), compared with control group (10.6 days). CONCLUSION: HSP-PC70 derived from tumor cells has strong immunogeneicity, and can activate CTLs with high peculiarity and killing activity. HSP-PC70 induced CTL adoptive immunotherapy can be a promising treatment for human to fight cancers.

Animals↗

PubMed2000

Dynamic changes of serum vascular endothelial growth factor levels in a rat myocardial infarction model.

OBJECTIVE: To investigate the dynamic changes of serum vascular endothelial growth factor (VEGF) levels in a rat model of acute myocardial infarction. MATERIALS AND METHODS: Eighty-eight adult male Sprague-Dawley rats weighing approximately 270 g we used in this study. Eighty rats were subjected to left coronary artery ligation, with 8 rats for each different duration of infarct. Eight sham-operated animals in which the left coronary artery was surgically exposed without ligation were used as controls. Blood samples were drawn from the right atrium before (sham animals) and 1, 3, 6, 12, 24 h and 2, 3, 5, 7, 14 d after myocardial infarction. The concentrations of serum VEGF were measured by a sensitive enzyme-linked imosorbent assay with a rabbit polyclonal antibody specific for VEGF. RESULTS: In the 8 control animals, the mean concentration of serum VEGF was 66.99 +/- 17.83 pg/ml. Six hours after myocardial infarction, the level of serum VEGF significantly increased to 125.68 +/- 28.07 pg/ml (P < 0.01 vs x sham controls), and reached a peak (240.61 +/- 70.63 pg/ml. P < 0.01 vs x sham animals) at 24 h after ligation and then decreased gradually over the remaining 2 weeks. However, the level remained significantly elevated for 14 d (107.64 +/- 30.13 pg/ml, P < 0.01 vs x sham controls). CONCLUSION: The present study shows that the levels of serum VEGF are markedly increased until 14 d in the rat model of acute myocardial infarction. The increased serum VEGF level may play an important role in the angiogenesis associated with myocardial infarction.

Animals↗

PubMed2000

[The study of induced circular dichroism of phenylalanine bridged metal bis-porphyrin].

L- and D-phenylalanine bridged zinc bis-porphyrin with the connecting chain at ortho and para position of two phenyl rings [o,o-C2-Phe-C2-(TPP)2Zn2 and p,p-C2-Phe-C2-(TPP)2Zn2] have been synthesized and characterized. o,o-C2-Phe-C2-(TPP)2Zn2 exhibited strong induced circular dichroism (ICD). While p,p-C2-Phe-C2-(TPP)2Zn2 exhibited no significant ICD. The ICD of present complexes were mainly determined by the pi-pi interaction and chiral excition coupling between two porphyrin moieties of the molecules. Our results also indicated that the existence of chiral center in a porphyrin molecule does not mean it would surely exhibit ICD.

Chelating Agents↗

PubMed2000

[The spectra and thermodynamics of axial coordination reaction of tailed valine tetraphenylporphintozinc with pyrimidine].

The electronic absorption spectra and thermodynamics of axial coordination reaction of 5-(4-valine butoxyphenyl)-10,15,20-tri(4-chlorophenyl)porphintozinc with pyrimidine in CHCl3 were studied. Coordination numbers and equilibrium constants of axial coordination reaction were measured by visible spectra techniques. The changes of standard molar enthalpies and standard molar entropies of reaction were obtained from the plots of ln beta vs 1/T. The influence of temperature on the axial reaction was discussed.

Porphyrins↗

PubMed1999

Caspase-mediated cleavage and functional changes of hematopoietic progenitor kinase 1 (HPK1).

Activation of c-Jun N-terminal kinase (JNK) by Fas ligation is caspase-dependent, suggesting that caspases may regulate activators of the JNK pathway. Here, we report that an upstream activator of JNK, hematopoietic progenitor kinase 1 (HPK1), was cleaved during apoptosis. Cleavage of HPK1 was blocked by peptide inhibitors for caspases. HPK1 was efficiently processed by recombinant caspase 3 in vitro. A conserved caspase recognition site, DDVD (amino acids 382 - 385), was found in the HPK1 protein sequence. By testing HPK1 proteins with in vivo and in vitro cleavage assays, we showed that aspartic acid residue 385 is the target for caspases. HPK1 cleavage separated the amino N-terminal kinase domain from the carboxyl C-terminal regulatory domain, and enhanced HPK1 kinase activity. Unlike the full-length HPK1, the N-terminal cleaved product failed to bind adaptor molecules Grb2 (growth factor receptor-bound protein 2) and Crk (CT10 regulator of kinase). The C-terminal fragment, although having three proline-rich domains, bound to Grb2 and Crk less efficiently than the full-length HPK1 protein. Taken together, the cleavage of HPK1 by caspase profoundly changed its biochemical properties.

Apoptosis↗

PubMed1999

A novel src homology 3 domain-containing adaptor protein, HIP-55, that interacts with hematopoietic progenitor kinase 1.

Hematopoietic progenitor kinase 1 (HPK1) is a member of the mitogen-activated protein kinase kinase kinase kinase (MAP4K) family and an upstream activator of the c-Jun N-terminal kinase (JNK) signaling cascade. HPK1 interacts, through its proline-rich domains, with growth factor receptor-bound 2 (Grb2), CT10-regulated kinase (Crk), and Crk-like (CrkL) adaptor proteins. We identified a novel HPK1-interacting protein of 55 kDa (HIP-55), similar to the mouse SH3P7 protein, containing an N-terminal actin-binding domain and a C-terminal Src homology 3 domain. We found that HPK1 bound to HIP-55 both in vitro and in vivo. When co-transfected, HIP-55 increased HPK1's kinase activity as well as JNK1's kinase activity. A dominant-negative HPK1 mutant blocked activation of JNK1 by HIP-55 showing that HIP-55 activates the JNK1 signaling pathway via HPK1. Our results identify a novel protein, HIP-55, that binds to HPK1 and regulates the JNK1 signaling cascade.

Amino Acid Sequence↗

PubMed1999

Mediation of TNF receptor-associated factor effector functions by apoptosis signal-regulating kinase-1 (ASK1).

Tumor necrosis factor-alpha (TNF), a major inflammatory cytokine, generates a wide variety of cellular responses via key cytoplasmic adaptor molecules named TNF receptor-associated factors (TRAFs). We report that TRAF2, TRAF5 and TRAF6 associate with apoptosis signal-regulating kinase 1 (ASK1), and a catalytically-inactive ASK1 mutant blocks stress-activated protein kinase (SAPK)/Jun NH2-terminal kinase (JNK) activation by these TRAFs. A truncated derivative of TRAF2, which inhibits SAPK activation by TNF, blocks TNF-induced ASK1 activation. Furthermore, protection from TNF-induced cell death conferred by an ASK1 mutant is dependent upon TRAF2. Hence, ASK1 is a common mediator of TRAF-regulated SAPK and apoptosis signaling, and the TRAF2 - ASK1 connection completes the signaling cascade from TNF to SAPK/JNK activation.

Animals↗

PubMed1999

The activity of microsomal triglyceride transfer protein is essential for accumulation of triglyceride within microsomes in McA-RH7777 cells. A unified model for the assembly of very low density lipoproteins.

Previously, based on distinct requirement of microsomal triglyceride transfer protein (MTP) and kinetics of triglyceride (TG) utilization, we concluded that assembly of very low density lipoproteins (VLDL) containing B48 or B100 was achieved through different paths (Wang, Y. , McLeod, R. S., and Yao, Z. (1997) J. Biol. Chem. 272, 12272-12278). To test if the apparent dual mechanisms were accounted for by apolipoprotein B (apoB) length, we studied VLDL assembly using transfected cells expressing various apoB forms (e.g. B64, B72, B80, and B100). For each apoB, enlargement of lipoprotein to form VLDL via bulk TG incorporation was induced by exogenous oleate, which could be blocked by MTP inhibitor BMS-197636 treatment. While particle enlargement was readily demonstrable by density ultracentrifugation for B64- and B72-VLDL, it was not obvious for B80- and B100-VLDL unless the VLDL was further resolved by cumulative rate flotation into VLDL(1) (S(f) > 100) and VLDL(2) (S(f) 20-100). BMS-197636 diminished B100 secretion in a dose-dependent manner (0.05-0.5 microM) and also blocked the particle enlargement from small to large B100-lipoproteins. These results yield a unified model that can accommodate VLDL assembly with all apoB forms, which invalidates our previous conclusion. To gain a better understanding of the MTP action, we examined the effect of BMS-197636 on lipid and apoB synthesis during VLDL assembly. While BMS-197636 (0.2 microM) entirely abolished B100-VLDL(1) assembly/secretion, it did not affect B100 translation or translocation across the microsomal membrane, nor did it affect TG synthesis and cell TG mass. However, BMS-197636 drastically decreased accumulation of [(3)H]glycerol-labeled TG and TG mass within microsomal lumen. The decreased TG accumulation was not a result of impaired B100-VLDL assembly, because in cells treated with brefeldin A (0.2 microgram/ml), the assembly of B100-VLDL was blocked yet lumenal TG accumulation was normal. Thus, MTP plays a role in facilitating accumulation of TG within microsomes, a prerequisite for the post-translational assembly of TG-enriched VLDL.

Animals↗

PubMed1999

Drug delivery of anticancer agents: water soluble 4-poly (ethylene glycol) derivatives of the lignan, podophyllotoxin.

This paper reports on the synthesis and in vivo oncolytic activity of a series of water-soluble acyl derivatives of polyethylene glycol (PEG) conjugated podophyllotoxin. Some analogs of the polymer conjugate showed significantly better activity in a murine leukemia model than native podophyllotoxin suspended in an intralipid emulsion. Additionally, when tested intravenously against a solid lung tumor (A549) model, some conjugated analogs were equivalent to the podophyllotoxin/intralipid emulsion, while those compounds demonstrating slower rates of plasma hydrolysis (in vitro) appeared to cause greater toxicity. There appeared to be an overall correlation between the in vivo antitumor activity of the conjugate and its rate of hydrolysis in vitro, with those showing faster release possessing greater antitumor activity. In conclusion, the solubilization and predictable release of podophyllotoxin from a PEG carrier was achieved and resulted in some derivatives demonstrating, at a minimum, equivalency with podophyllotoxin when administered on an equal molar basis. Further studies may be warranted to assess the PEG-conjugates pharmacokinetics and therapeutic indices in leukemic models.

Animals↗

PubMed1999

[Study on a purified and inactivated Japanese encephalitis vaccine prepared on Vero cells using SA14-14-2 attenuated virus strain].

OBJECTIVE: To develop a kind of new Japanese Encephalitis (JE) vaccine prepared on Vero cells. METHODS: A JE attenuated virus strain SA14-14-2 was adapted on Vero cells for preparation of purified inactivated vaccine. Comparison of the growth curves of SA14-14-2 in roller bottle and in spinner flask was made. After the virus inoculation and absorption on Vero cells for 2 hours, cultures were replaced with serum-free MEM, the culture supernatants were harvested on day 2,4,6 after inoculation. The virus fluids were pooled, concentrated by 8% PEG, and purified on 15%-60% sucrose density gradients. The purified virus was inactivated with 0.02% formalin. RESULTS: It showed that virus titer was higher and maintained longer in roller bottle. Mice vaccinated twicely with 0.5 microgram dose of the purified inactivated vaccine induced neutralizing antibody titers equal to that of the mice vaccinated with primary hamster kidney inactivated vaccine. CONCLUSION: This Vero cell prepared purified and inactivated JE vaccine made by SA14-14-2 strain could be used for human as a kind of new JE vaccine.

Animals↗

PubMed1999

Hematopoietic progenitor kinase 1 is a component of transforming growth factor beta-induced c-Jun N-terminal kinase signaling cascade.

The c-Jun N-terminal kinase (JNK) signaling pathway is involved in transforming growth factor beta (TGF-beta) signaling in a variety of cell systems. We report here that hematopoietic progenitor kinase 1 (HPK1), a novel Ste20-like protein serine/threonine kinase, serves as an upstream mediator for the TGF-beta-activated JNK1 cascade in 293T cells. TGF-beta treatment resulted in a time-dependent activation of HPK1, which was accompanied by similar kinetics of JNK1 activation. The activation of JNK1 by TGF-beta was abrogated by a kinase-defective HPK1 mutant but not by a kinase-defective mutant of kinase homologous to Ste20/Sps1. This result indicates that HPK1 is specifically required for TGF-beta-induced activation of JNK1. We also found that TGF-beta-induced JNK1 activation was blocked by a kinase-defective mutant of TGF-beta-activated kinase 1 (TAK1). In addition, interaction between HPK1 and TAK1 was observed in transient transfection assays, and this interaction was enhanced by TGF-beta treatment. Both stress-activated protein kinase/extracellular signal-regulated kinase kinase (SEK) and mitogen-activated protein kinase kinase 7 (MKK7) are immediate upstream activators of JNK1. Although SEK and MKK7 acted downstream of TAK1, only a kinase-defective SEK mutant blocked TGF-beta-induced activation of JNK1, indicating that the TGF-beta signal is relayed solely through SEK, but not MKK7, in vivo. Furthermore, TGF-beta-induced activating protein 1 activation was blocked by a HPK1 mutant, as well as by TAK1 and SEK mutants. Taken together, these studies establish a potential cascade of TGF-beta-activated interacting kinases beginning with HPK1, a Ste20 homolog, and ending in JNK1 activation: HPK1 --> TAK1 --> SEK --> JNK1.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1999

Identification of domains in apolipoprotein B100 that confer a high requirement for the microsomal triglyceride transfer protein.

The microsomal triglyceride transfer protein (MTP) is required for the assembly and secretion of apoB-containing lipoproteins. To investigate the role of MTP in lipoprotein assembly, we determined the ability of carboxyl-terminally truncated forms of apoB to be secreted from cells treated with the MTP inhibitor 4'-bromo-3'-methylmetaqualone (Benoist, F., Nicodeme, E., and Grand-Perret, T. (1996) Eur. J. Biochem. 240, 713-720). In Caco-2 and mhAT3F cells that produce apoB100 and apoB48, the inhibitor preferentially blocked apoB100 secretion. When the inhibitor was tested on McA-RH7777 cells stably transfected with cDNAs encoding human apoB100, apoB72, apoB53, apoB29, and apoB18, the secretion of apoB100, apoB72, and apoB53 was preferentially impaired relative to apoB48 and shorter forms. To delineate the region between apoB48 and apoB53 that has a high requirement for MTP, we used puromycin to generate a range of truncated forms of apoB in HepG2 cells. The secretion of apoB53 and longer forms of apoB was markedly affected by low concentrations of the MTP inhibitor (approximately 1 microM), whereas apoB51 and smaller forms of apoB were only affected at higher concentrations (> 10 microM). The size-related sensitivity to MTP inhibitor was not due to late processing or retention, since the same result was observed when nascent lipoproteins were isolated from the endoplasmic reticulum. The MTP inhibitor did not alter the density of the secreted lipoproteins, indicating that each apoB polypeptide requires a minimally defined amount of lipid to attain a secretable conformation. Our results suggest that the folding of the domain between apoB51 and apoB53 has a high requirement for lipid. This domain is predicted to form amphipathic alpha-helices and to bind lipid reversibly. It proceeds and is followed by rigid amphipathic beta-sheets that are predicted to associate with lipid irreversibly. We speculate that these domains enable apoB to switch from a stable lipid-poor conformation in apoB48 to another lipid-rich conformation in apoB100 during lipoprotein assembly.

Apolipoprotein B-100↗