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Biomedical subjects

C Li

Publications and source records attributed to C Li.

At least 829 records · Page 46Linked to original sources
PubMed1997

[Effects of IFN-alpha on the expressions of perforin and granzymes in IL-2 activated lymphocytes].

OBJECTIVE: To study the effect of IFN-alpha on the expressions of perforin and granzymes in IL-2-activated-lymphocytes. METHODS: NK and LAK activities were assayed by 4 hour standard 51Cr release test, the activity of perforin was detected by hemolysis method, expression of granzyme B was measured by ABC immunohistological method, expression of granzyme A was measured by BLT method. RESULTS: IFN-alpha significantly augmented the activities of NK and LAK in IL-2 activated peripheral blood lymphocytes (PBL) after 1 day culture. Perforin activity in lymphocytes was increased after 1 day exposure to IL-2 or IFN-alpha, and was enhanced when exposed to the combination of IL-2 and IFN-alpha. After 3 day culture, the perforin activity remained high in lymphocytes activated by IL-2 alone or in combination with IFN-alpha, while declined to control level in IFN-alpha exposed group. IL-2 and IFN-alpha alone or in combination had no effect on expression of granzyme A and B. CONCLUSION: IFN-alpha enhances the cytotoxicity of lymphocytes activated by IL-2. The mechanism might be that IFN-alpha upregulates the perforin expression.

Gene Expression Regulation↗
PubMed1997

[GM-CSF regulates the Vp16 induced leukemic cell apoptosis].

OBJECTIVE: To explore the regulatory effects of granulocyte-macrophage colony stimulating factor (GM-CSF) on the apoptosis of leukemic cells induced by Vp16. METHODS: High expression retrovirus vector, N2A/CMV/GM-CSF, was constructed and transferred into human leukemic cell line HL-60, and Vp16 (final concentration 10microg/ml) was administered to transferred or nontransferred HL-60 cells. RESULTS: After Vp16 treatment, characteristic changes for apoptosis emerged in HL-60 cells. However, these findings did not emerge in GM-CSF gene transferred HL-60 cells. CONCLUSION: GM-CSF can suppress the leukemic cell apoptosis induced by Vp16.

Apoptosis↗
PubMed1997

[Study on the relationship between the expression of adhesion molecules and the invasiveness of acute myeloid leukemia cells].

OBJECTIVE: To study the relationship between the expression of adhesion molecules CD49d (VLA-4) and CD11a (LFA-1) and the invasiveness of acute myeloid leukemia (AML) cells. METHODS: Peripheral blood and/or bone marrow samples from 50 AML patients were investigated by APAAP and Western blotting method. RESULTS: Extramedullary invasion developed in 32 of 50 patients (64%). The expression of CD49d and CD11a in the invasive group was much higher than that in the non-invasive group (P<0.005), while the difference between the leukemic cells from bone marrow and peripheral blood for CD49d/CD11a expression was not significant. CONCLUSION: AML cells might adhere to and get through vascular endothelium by CD49d/VCAM-1 and CD11a/ICAM-1 adhesion mechanism, and the expressions of CD49d and CD11a were not critically responsible for the release of leukemic cells from bone marrow.

Adolescent↗
PubMed1997

[In vitro reversal of homoharringtonine resistance by the combination of tamoxifen and verapamil].

OBJECTIVE: To investigate the reversal of homoharringtonine (HHT)-resistance by tamoxifen (TAM) or verapamil (VER) alone or in combination. METHODS: The drug-sensitivity test was performed with semisolid agar culture. RESULTS: The cytotoxicity of HHT to K562/S cells was not enhanced by TAM or VER alone or in combination,but HHT resistance in HHT resistant cells (K562/H20) was reversed by VER and TAM at nontoxic doses (4micromol/L or 8micromol/L). The IC50 of K562/H20 for HHT decreased from 446.8 +/- 0.08microg/L to 45.1 +/- 0.02microg/L in the presence of 4micromol/L of VER, to 22.4 +/- 0.03microg/L in 8micromol/L of VER, to 85.1 +/- 0.03microg/L in 4micromol/L of TAM and to 26.4 +/- 0.02microg/L in 8micromol/L of TAM. In the presence of combinations of 2micromol/L VER and 4micromol/L TAM and of 2micromol/L VER and 8micromol/L TAM, IC50 of K562/H20 decreased to 30.4 +/- 0.02microg/L and 4.3 +/- 0.04microg/L, respectively. CONCLUSION: HHT-resistance could be reversed by VER or TAM alone, and the combination of the two drugs showed a synergistic effect.

Animals↗
PubMed1997

[The killing effect of IL-2 and IFN-alpha activated bone marrow on K562 leukemic cell].

OBJECTIVE: To evaluate the killing effect of IL-2 and IFN-alpha activated bone marrow cells on K562 cells. METHODS: Semi-solid colony assay was used. RESULTS: Bone marrow from leukemia patients in remission was activated in vitro with IL-2 for 3 days. The activated bone marrow (ABM) displayed killing effects of 0.31 approximately 2.30 logs on K562 cells, this killing effects was further increased to 0. 30 approximately > 3.15 logs when IFN-alpha added with IL-2 to the marrow for activation. IL-2 alone or in combination with IFN-alpha showed no inhibition of CFU-GM and K562 cells. Compared with IL-2 or IFN-alpha alone, the combination of the two cytokines could more effectively maintain the killing effect of ABM on leukemic cells. CONCLUSION: IFN-alpha can augment the purging effect of IL-2 ABM and combination of the two cytokines can effectively maintain the cytotoxicity of ABM.

Bone Marrow Cells↗
PubMed1997

[Liposome-mediated gene transfer into bone marrow cells and its in vitro expansion].

OBJECTIVE: To explore the efficiency of liposome-mediated gene transfer into bone marrow cells and the stability of its expression. METHODS: Two marker genes (Neo and Lac Z) mediated by liposome were co-transferred into bone marrow cells. Following G418 screening,the positive cells were enriched and expanded in vitro. RESULTS: The liposome-mediated gene transfer rate in bone marrow cells was 13.33 +/- 2.68%, and after G418 screening, it was 46.06 +/- 3.47%. The blue colouring rates with X-gal staining of these cells were not significantly different before and after expansion. CONCLUSION: Liposome-mediated gene transfer in bone marrow cells is highly efficient and the expression of the transferred gene is stable.

Bone Marrow Cells↗
PubMed1997

[Relationship between bcl-X(L) expression and sensitivity to chemotherapy in acute myeloid leukemic cells].

OBJECTIVE: To investigate the characteristics and regulation of apoptosis in acute myeloid leukemic cells. METHODS: Flow cytometry, DNA electrophoresis and Northern blot were used to analyze the expression of bcl-X(L) before and after Vp16 treatment, and the relationships between bcl-X(L) expression and apoptotic sensitivity, clinical features and prognosis were also analyzed. RESULTS: Most of the leukemic cells from AML patients overexpressed bcl-X(L) mRNA. The expression of bcl-X(L) was still maintained high level after Vp16 treatment in patients with pretreatment overexpression. These patients were resistant to apoptosis, poor responsed to chemotherapy and associated with adverse prognostic features, such as high WBC counts, local leukemic infiltrations. Bone marrow cells from long-term remission AML patients and normal controls also showed bcl-X(L) downregulation after in vitro Vp16 treatment, but the apoptotic rates were lower than that in nonremissive AML. CONCLUSION: Overexpression of bcl-XL played an important role in leukemogenesis and drug resistance. Downregulation of bcl-X(L) was necessary but not sufficient to initiate apoptosis.

Adolescent↗
PubMed1997

[The spectrum analysis of high performance liquid chromatographic peak by ultraviolet-visible spectrophotometric detectors].

In the analysis of high performance liquid chromatography (HPLC), the qualification of chromatographic peak can be carried out by the methods of adding standard, comparing retention time and absorption spectrum etc. This paper reports a simple and practical method for measurement of absorption spectrum of HPLC peak by ultraviolet and visible variable wavelength detector. A BASIC program was edited with Shimadzu C-R4A data processor. Stopping the pump at the retention time we use the program to analyse absorption spectrum of the peak and the absorption spectrum of standard (Cr, PU, UA) by Shimadzu UV-2201 UV-VIS recording spectrophotometer and the absorption spectrum of standard (-S) with sample (-T) by this method are presented. The figure shows that the absorption spectra of the samples of Cr, PU and UA almost completely overlapped with those of the standards. The results showed that this method is reliable.

English Abstract↗
PubMed1997

[Development of a SIRI-TOFMS and the application research progress].

The only one set of Sputter Initiated Resonance Ionization-Time of Flight Mass Spectrometer (SIRI-TOFMS) in China was designed and developed. A liquid gallium ion source with micron level diameter of beam, frame-style piezoeletric ceramic sub-micron sample manipulator, a secondary electron imaging system and a computer controlled precise targeting system as well as a real colour big screen image displaying system were added so as to improve its microanalysis capability. By means of this apparatus, trace analysis of Au in minerals and Cu in standard steel samples were carried out. The detection limit of them is 40ng/ and microg/g level, respectively. Aside from the above detections, other preliminary researches ere also performed.

English Abstract↗
PubMed1997

Persistent spontaneous oral dyskinesias in haloperidol-withdrawn rats neonatally lesioned with 6-hydroxydopamine: absence of an association with the Bmax for [3H]raclopride binding to neostriatal homogenates.

To investigate the influence of dopamine (DA) nerves on haloperidol (HAL)-induced oral dyskinesias, rats were first injected at 3 days after birth with 6-hydroxydopamine HBr (200 micrograms i.c.v., salt form; 6-OHDA) or vehicle, after desipramine HCl (20 mg/kg i.p., 1 hr) pretreatment. Two months later HAL (1.5 mg/kg/day, 2 days a week for 4 weeks, then daily for 10 months) was added to the drinking water of half the rats. Numbers of vacuous chewing movements, recorded in 1-min increments every 10 min for 1 hr, increased from < 5 to about 17 oral movements per session in intact rats, 14 weeks after instituting HAL (P < .01 vs. intact rats drinking tap water). In HAL-treated 6-OHDA-lesioned rats, oral activity increased to > 30 oral movements per session (P < .01 vs. HAL-treated intact rats). These levels of oral activity persisted in intact and 6-OHDA-lesioned rats as long as HAL was administered. After 11 months of HAL treatment, but 8 or 9 days after HAL withdrawal, DA was found to be reduced 97%, whereas serotonin was increased 29% in the striatum of 6-OHDA-lesioned rats. In HAL-treated intact and lesioned rats the Bmax for DA D2 binding sites was elevated about 70%. With reverse transcription polymerase chain reaction, the mRNA level for DA D2L but not D2S receptors was also found to be elevated about 70%. In a fraction of 6-OHDA-lesioned rats that were observed for 8 months after HAL withdrawal, oral activity persisted without decrement and was not accompanied by a change in the Bmax or mRNA level for DA D2 receptors. These findings demonstrate that in rats largely DA-denervated as neonates, long-term HAL treatment produces an unusually high number of oral movements that persists for 8 months after HAL withdrawal and is not accompanied by an increase in DA D2 receptor expression.

Animals↗
PubMed1997

Developmental and Photoregulation of Three Neurospora crassa Carotenogenic Genes during Conidiation Induced by Desiccation

Neurospora crassa asexual sporulation (conidiation) is induced by different cues including desiccating aerial environments. Three of the genes that are expressed during this developmental pathway are the albino (al) genes, which encode carotenoid biosynthetic enzymes. If conidiation is induced by nutrient deprivation in liquid culture, two overlapping al-3 mRNAs, al-3 (m) and al-3 (c), are expressed (Arpaia et al., 1995, Dev. Biol. 170, 620-635). Here we quantitate accumulation of each of the four albino gene messages, al-1, al-2, al-3 (m), and al-3 (c), in conidiating wild-type cultures and in cultures of two mutants defective in photoinduced carotenogenesis, wc-1 and wc-2. Of the four albino gene transcripts, only al-1 expression is developmentally regulated in wild-type cultures conidiating in darkness. Expression of all four albino gene transcripts is developmentally regulated in conidiating wc-1 or wc-2 cultures. Unlike other albino gene transcripts, expression of al-3 (c) is photoregulated only early in conidiation. The fld and fl mutants are defective in conidiation with development halting at distinct early stages of spore formation. In desiccated fld and fl cultures al-1, al-2, and al-3 (m) transcript accumulation is observed to peak early and then decline, while al-3 (c) transcript accumulation increases with time.

Journal Article↗
PubMed1997

Prevalence of human papillomavirus in middle ear carcinoma associated with chronic otitis media.

Squamous cell carcinoma of the middle ear (MESCC) is an uncommon tumor and is associated with a history of long-term chronic otitis media (COM) in most cases. Although the human papillomaviruses (HPVs) have been implicated in many human neoplasms, its role in the pathogenesis of MESCC has not been studied. Polymerase chain reaction (PCR) using consensus primers for the detection of HPV types 6, 11, 16, 18, 31, 33, 52b, and 58 was applied in screening fourteen cases of MESCC from archival material. Further subtyping was performed by restriction enzyme digestion of PCR products and by in situ hybridization method on tissue sections. Of the fourteen cases of MESCC, eleven were found to have HPV DNA. HPV-16 was detected in all positive cases. Five cases revealed both HPV-16 and -18. A history of long-term COM (> 3 years) was found in thirteen of the cases. This is the first report to localize HPV-16/18 in MESCC on both the tissue level and the molecular level. The high prevalence of HPV in COM-associated MESCC therefore provides a good model to explain the pathogenesis of chronic-inflammation-related human malignancies.

Adult↗
PubMed1997

Developmental and photoregulation of three Neurospora crassa carotenogenic genes during conidiation induced by desiccation.

Neurospora crassa asexual sporulation (conidiation) is induced by different cues including desiccating aerial environments. Three of the genes that are expressed during this developmental pathway are the albino (al) genes, which encode carotenoid biosynthetic enzymes. If conidiation is induced by nutrient deprivation in liquid culture, two overlapping al-3 mRNAs, al-3 (m) and al-3 (c), are expressed (Arpaia et al., 1995, Dev. Biol. 170, 620-635). Here we quantitate accumulation of each of the four albino gene messages, al-1, al-2, al-3 (m), and al-3 (c), in conidiating wild-type cultures and in cultures of two mutants defective in photoinduced carotenogenesis, wc-1 and wc-2. Of the four albino gene transcripts, only al-1 expression is developmentally regulated in wild-type cultures conidiating in darkness. Expression of all four albino gene transcripts is developmentally regulated in conidiating wc-1 or wc-2 cultures. Unlike other albino gene transcripts, expression of al-3 (c) is photoregulated only early in conidiation. The fld and fl mutants are defective in conidiation with development halting at distinct early stages of spore formation. In desiccated fld and fl cultures al-1, al-2, and al-3 (m) transcript accumulation is observed to peak early and then decline, while al-3 (c) transcript accumulation increases with time.

Carotenoids↗
PubMed1997

Synthesis, biodistribution and imaging properties of indium-111-DTPA-paclitaxel in mice bearing mammary tumors.

UNLABELLED: Paclitaxel, an antineoplastic agent that stabilizes microtubules and arrests cells in the G2/M cell cycle phase, has shown activity against many common cancers, including ovarian and breast tumors. In order to evaluate the potential value of radiolabeled paclitaxel as an imaging tool in tumors, we synthesized 111In-DEPA-paclitaxel and investigated its biodistribution and gamma scintigraphic imaging properties. METHODS: Mice bearing a paclitaxel-responsive mammary tumor (MCA-4) were used. DTPA-paclitaxel was labeled with 111In with a radiochemical yield of 84% and radiochemical purity of 90%. Each mouse received 5 microCi of radiotracers intravenously for biodistribution studies and 100 microCi for gamma scintigraphic studies. Indium-111-DTPA was used as a control. RESULTS: In tumor-bearing mice, 111In-DTPA was characterized by rapid clearance from the plasma with negligible retention in the tumor, the liver and other body parts. In contrast, 111In-DTPA-paclitaxel exhibited a pharmacological profile resembling that of paclitaxel. Furthermore, a significant uptake of 111In-DTPA-paclitaxel was observed in the tumor. The tumor-to-muscle ratios were 2.64, 3.16 and 6.94 at 30 min, 2 hr and 24 hr, respectively, although absolute uptake in the tumor decreased from 1.95% (injected dose/g) at 30 min to 0.21% at 24 hr after injection. The tumor-to-blood ratio reached 50 at 24 hr after injection. Gamma scintigraphy and autoradiographic studies clearly showed the retention of radiolabeled paclitaxel in the tumor 24 hr after injection. CONCLUSION: These studies suggest that 111In-DTPA-paclitaxel may be clinically useful in studying the uptake of paclitaxel in solid tumors.

Animals↗
PubMed1997

Increased beta-catenin protein and somatic APC mutations in sporadic aggressive fibromatoses (desmoid tumors).

Sporadic aggressive fibromatosis (also called desmoid tumor) is a monoclonal proliferation of spindle (fibrocyte-like) cells that is locally invasive but does not metastasize. A similarity to abdominal fibromatoses (desmoids) in familial adenomatous polyposis and a cytogenetic study showing partial deletion of 5q in a subset of aggressive fibromatoses suggests that the adenomatous polyposis coli (APC) gene plays a role in its pathogenesis. APC helps regulate the cellular level of beta-catenin, which is a downstream mediator in Wnt (Wingless) signaling. beta-Catenin has a nuclear function (binds transcription factors) and a cell membrane function (is a component of epithelial cell adherens junctions). Six cases of aggressive fibromatosis of the extremities from patients without familial adenomatous polyposis, or a family history of colon cancer, were studied. Immunohistochemistry, using carboxy and amino terminus antibodies to APC, and DNA sequencing showed that three of the six contained an APC-truncating mutation, whereas normal tissues did not contain a mutation. Western blot and Northern dot blot showed that all six tumors had a higher level of beta-catenin protein than surrounding normal tissues, despite containing similar levels of beta-catenin mRNA. Immunohistochemistry localized beta-catenin throughout the cell in tumor tissues, although it localized more to the periphery in cells from normal tissues. Reverse transcription polymerase chain reaction showed that the tumors expressed N-cadherin but not E-cadherin (a pattern of expression of proteins making up adherens junctions similar to fibrocytes), suggesting that the specific adherens junctions present in epithelial cells are not necessary for beta-catenin function. Increased beta-catenin may cause the growth advantage of cells in this tumor through a nuclear mechanism. The increased protein level, relative to the RNA level, suggests that beta-catenin is degraded at a lower rate compared with normal tissues. In some cases, this is caused by a somatic mutation resulting in a truncated APC protein.

Adenomatous Polyposis Coli Protein↗
PubMed1997

The CAG repeats number of spinocerebellar ataxia type 1 gene in normal Taiwanese and in patients with dominant inherited ataxia.

Spinocerebellar ataxia type 1 (SCA 1) is an autosomal dominant disorder characterized by neurodegeneration of the cerebellum, spinal cord and brainstem. This neurodegeneration disease is associated with expansion of unstable CAG repeats within the coding region of the gene. We are conducting a local survey of the normal population and candidate patients to analyze the CAG repeats in SCA 1 gene. So far, we have collected peripheral blood from 78 normal individuals and 10 patients with dominant inherited ataxia disorders, and assayed the SCA1 CAG trinucleotide repeat using genomic polymerase chain reaction (PCR). Even though no local SCA 1 patients have been identified, we have established the distributions of the CAG repeat units of SCA 1 gene in the normal population in Taiwan. The normal range of CAG repeats is from 22 to 33 repeats, with the most common being 30 repeats. The range is relatively narrow compared to that reported for other ethnic groups. In addition, direct genomic PCR analysis of the SCA 1 gene from villous DNA has been successful in our laboratory. Screening of SCA 1 patients from patients with dominant inherited ataxia is currently underway in our laboratory. Here, we demonstrate that our molecular analysis technique makes possible the quick and accurate diagnosis of SCA1 patients and prenatal screening for SCA 1 families.

Ataxin-1↗
PubMed1997

Construction and identification of a recombinant adenovirus which expresses human interferon-gamma.

An E1-deleted adenoviral vector, pAdl2/RSV-IFN-bpA, harboring human IFN-gamma cDNA, and plasmid pJM17 were cotransfected into a human embryo kidney cell line 293 by the calcium-phosphate precipitation method. Six strains of recombinant adenovirus (rAd) were obtained after 11-day incubation. PCR analysis indicated that all six rAds contained human IFN-gamma cDNA. The biological activity of IFN-gamma was detected in the supernatant of the cultured 293 cells following rAd infection, and it could be blocked by the antibody against IFN-gamma. The B16F10 cells infected with the purified rAd (RSV/IFN-01) didn't show cytopathic effect (CPE), and more biological activity of IFN-gamma was detected in the supernatant of the infected B16F10 cells with increased MOI (multiple of infection) values. Therefore, the recombinant adenovirus constructed in this study can express and secrete human IFN-gamma.

Adenoviruses, Human↗