Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 415 records · Page 23Linked to original sources

PubMed1999

Cytokines and apoptotic molecules in experimental melanin-protein induced uveitis (EMIU) and experimental autoimmune uveoretinitis (EAU).

The cytokine profile and occurrence of apoptosis during experimental melanin-protein induced uveitis (EMIU) were investigated and compared with that of experimental autoimmune uveoretinitis (EAU). EMIU or EAU was induced in Lewis rats. Eyes were collected at different time points after immunization. Cytokine mRNA expression was identified in the inflammatory cells in the uvea of EMIU rats; IL-2, IFN-gamma and IL-12 increased at the peak of the inflammation, and then tapered off as inflammation subsided. IL-4 and IL-10 increased at the peak of ocular inflammation, and persisted with inflammation resolved. Fas and FasL were expressed consistently in ocular resident cells of EMIU, but were elevated in EAU. In EAU, Bcl-2 expression showed a sharp peak in inflammatory cells but not in the resident cells. In EMIU, high levels of Bcl-2 were present and persisted in both ocular resident and inflammatory cells. Expression of Bax was relatively stable in both EAU and EMIU. Cellular DNA fragmentation was detected in the retinal glial cells of EAU and some inflammatory cells of EMIU. In EMIU, the dynamics of Th1 cytokines were consistent with the ocular inflammation, whereas persistent expression of Th2 cytokines was consistent with their known regulatory role. The continuous high expression of Bcl-2 and the high ratio of Bcl-2 to Bax in the eyes of EMIU may possibly contribute to prevention of ocular tissue damage, and of inflammatory cells from undergoing apoptosis, thus resulting in chronic recurrent inflammation.

Animals↗

PubMed1999

Receptor-mediated interleukin-2 gene transfer into human hepatoma cells.

Receptor-mediated gene delivery is an attractive method for gene transfer in vitro and shows promise for in vivo gene therapy applications. In the current study, we have selected the cytokine interleukin-2 (IL-2) gene to explore the feasibility of receptor-mediated gene transfer into human hepatocellular carcinoma HepG2 cells, using Epstein-Barr virus (EBV)-based vectors. We have developed a targeted DNA delivery system for the treatment of liver cancer by gene therapy. This system utilizes the hepatocyte-specific asialoglycoprotein receptor, which is uniquely expressed on liver cell membranes but not present on other cell types. Galactosylated histone, a ligand to the asialoglycoprotein receptors, was synthesized, and a new EBV-based expression vector bearing the human IL-2 cDNA was constructed and conjugated to the ligand through ionic interactions. The ligand/IL-2 DNA complex was able to bind specifically to cell-surface receptors on the target cell and, when incubated with HepG2 cells, resulted in elevated levels of IL-2 gene expression. These results indicate that therapeutic genes like IL-2 in ligand/DNA complex can be transferred into hepatoma cells via the hepatocyte receptor. This study constitutes an encouraging first step in the assessment of receptor-mediated gene transfer as a technique for gene therapy in liver cancer.

Animals↗

PubMed1999

Expanded tumor-reactive CD4+ T-cell responses to human cancers induced by secondary anti-CD3/anti-CD28 activation.

Generation of tumor-reactive T cells in large numbers ex vivo is a requisite step in the adoptive immunotherapy of patients. We examined the immune responses of T cells derived from tumor vaccine-primed lymph nodes activated with anti-CD3 alone and with an anti-CD3/anti-CD28 combination. Nylon wool-purified CD3+ cells were isolated from vaccine-primed lymph nodes obtained from melanoma, renal cell, and head and neck cancer patients. In the absence of antigen-presenting cells, activation with anti-CD3/anti-CD28 greatly enhanced subsequent T-cell expansion in interleukin 2 (>100-fold), compared to anti-CD3 alone. CD4+ T cells were preferentially stimulated. In four of eight patients, we found evidence of CD4+ cellular responses to autologous tumors by cytokine release assays. Positively selected CD4+ cells activated with anti-CD3/anti-CD28 released greater amounts of cytokine (IFN-gamma and granulocyte macrophage colony-stimulating factor) in response to autologous tumors compared to cells activated by anti-CD3 alone. The CD4+ reactivity was MHC class II restricted and appeared to be associated with the expression of class II molecules on the vaccinating tumor cells. The CD4+ T-cell responses to class II-restricted tumor-associated antigens in patients with renal cell cancers represent unique findings.

Antibodies, Monoclonal↗

PubMed1999

[A comparative study of HLA-A locus in northern and southern Chinese bymeans of PCR/SSOP typing].

OBJECTIVE: To compare the HLA-A locus in a population selected from Beijing (northern group) with that in a population selected from Guangzhou (southern group). METHODS: HLA typing was performed by using PCR/SSOP method. A pair of primer and 54 probes were used. RESULTS: In 18 alleles identified, the differences in gene frequency between northern and southern Chinese were found. In northern group, A*0205, 0210 and 2901 were absent, and the frequencies of A*2601, 3001 and 3101 were higher than those of southern group; while in southern group, A*3103, 3201 and 6801 were absent, the frequencies of A*0203 and 1101 were higher than those of northern group; and in addition, six subtypes of A2 serological specificity, namely A*0201, 0203, 0205, 0206, 0207 and 0210, were found, in which A*0201 predominated. CONCLUSION: There are some differences in the genetic background of northern and southern Chinese. A2 subtypes have important implications for unrelated-donor transplantation.

Alleles↗

PubMed1999

Retigabine N-glucuronidation and its potential role in enterohepatic circulation.

The metabolism of retigabine in humans and dogs is dominated by N-glucuronidation (), whereas in rats, a multitude of metabolites of this new anticonvulsant is observed (). The comparison of the in vivo and in vitro kinetics of retigabine N-glucuronidation in these species identified a constant ratio between retigabine and retigabine N-glucuronide in vivo in humans and dog. An enterohepatic circulation of retigabine in these species is likely to be the result of reversible glucuronidation-deglucuronidation reactions. Rats did not show such a phenomenon, indicating that enterohepatic circulation of retigabine via retigabine N-glucuronide does not occur in this species. In the rat, 90% of retigabine N-glucuronidation is catalyzed by UDP-glucuronosyltransferase (UGT)1A1 and UGT1A2, whereas family 2 UGT enzymes contribute also. Of ten recombinant human UGTs, only UGTs 1A1, 1A3, 1A4, and 1A9 catalyzed the N-glucuronidation of retigabine. From the known substrate specificities of UGT1A4 toward lamotrigine and bilirubin and our activity and inhibition data, we conclude that UGT1A4 is a major retigabine N-glucuronosyl transferase in vivo and significantly contributes to the enterohepatic cycling of the drug.

Animals↗

PubMed1999

Known mutations of apoB account for only a small minority of hypobetalipoproteinemia.

Low LDL cholesterol and apoB levels in plasma cosegregate with mutations of apoB in some kindreds with familial hypobetalipoproteinemia. Approximately 35 apoB mutations, many specifying apoB truncations, have been described. Based on the centile nomenclature where the full-length nature apoB consisting of 4536 amino acids is designated as apoB-100, only those truncations of apoB >25% of normal length are detectable in plasma. Previously, we reported on five unrelated kindreds with familial hypobetalipoproteinemia in whom although no apoB truncations were detectable in plasma, low apoB levels were nevertheless linked to the apoB gene. In one of those kindreds, we reported a donor splice site mutation in intron 5 (specifying apoB- 4). We now describe a nonsense mutation in exon 10 (apoB-9) in two of the other unrelated families. Both the apoB-4 and apoB-9 mutations have been reported by others in unrelated families. Recurrent mutations of apoB-40 and apoB-55 also have been reported, suggesting that recurrent mutations of apoB may account for an appreciable proportion of familial hypobetalipoproteinemia kindreds. To test this hypothesis, we searched for four apoB mutations whose products are not detected in plasma including the apoB-4, apoB-9, and two other previously reported mutations in exons 21 and 25. We studied three groups with plasma cholesterols <130 mg/dl in whom no apoB truncations were detected in plasma: a) 28 FHBL probands from St. Louis, b) 151 individual St. Louisians, and c) 28 individual Sicilians. One subject from the 28 kindreds and two subjects among 151 hypobeta individuals from St. Louis harbored the exon 10 mutation. None of the other mutations were detected. Thus, among hypobeta lipoproteinemic subjects without any detectable apoB truncations in plasma, <5% had an apoB truncation-producing mutation. As only about 0.5% of hypobeta lipoproteinemic subjects have plasma-detectable apoB truncations, our data suggest that the known apoB truncations account for only a small proportion of hypocholesterolemia.

Apolipoproteins B↗

PubMed1999

Estrogen receptor methylation is associated with improved survival in adult acute myeloid leukemia.

Estrogen receptor methylation (ERM) is a frequent molecular alteration in adult acute myeloid leukemia (AML). In this study, we sought to determine the clinical characteristics and prognostic significance of ERM in AML. ERM was determined for 268 patients who had leukemic blasts available for molecular analysis. ERM was measured by Southern blot analysis, and results were obtained for 261 patients (ages 17-69). ERM ranged from 0-99.1%, with a median of 25%. One hundred sixty patients (61%) had ERM values over 15% and were considered ERM+. In a subset of patients analyzed, ERM+ samples had markedly lower ER gene expression compared with ERM- samples. In multiple regression analyses of patient and disease characteristics at diagnosis, two factors had significant independent association with ERM: ERM decreased with increasing age (P = 0.0001) and was significantly lower in patients with French-American-British classification M4 or M5 (P = 0.0019). In regression analyses of outcome measures, ERM had no significant impact on complete remission rate after initial induction therapy. However, ERM+ patients had significantly better overall survival [OS; 18% at 6 years; 95% confidence interval (CI), 12-24% versus 9%; CI, 3-14% for ERM- patients; P = 0.022]. In multiple regression analyses, OS increased with increasing ERM (P = 0.0044). Similar results were seen for relapse-free survival (23% at 6 years; CI, 15-32% for ERM+ versus 10%; CI, 2-19% for ERM-), although the effect of ERM was not statistically significant (P = 0.15 in multiple regression analysis). Our results indicate that ERM at diagnosis may be a favorable prognostic factor for OS in adult AML.

Acute Disease↗

PubMed1999

[Inhibitory effect of replication and expression of HDV by antisense oligodeoxynucleotides in H1 delta 9 cell].

OBJECTIVE: To study inhibitory effect of an antisense oligodeoxynucleotide (ASODN) and its phosphorothioate (S-ASODN) on replication and expression of HDV in H1 delta 9 cell. METHODS: In previous studies, it was proved that the ASODNs which are complementary to genomic HDV ribozyme self-cleavage site and stem I regions can inhibit availably genomic HDV ribozyme activity. In the present study, a 15-mer ASODN and S-ASODS which are complementary to this region (nucleotide 684-698) were added to medium of cultured H1 delta 9 cell. HDAg and HDV cDNA were detected by ELISA and Dot blot hybridization. RESULTS: Twenty-fourth hour after 6 mumol/L ASODN and S-ASODN were added, both the secreting amount of HDAg in the supernatant and HDV RNA were inhibited. The inhibiting rates were 76.14% and 84.50% respectively. When the concentration of S-ASODN was 2, 4, 6 mumol/L, the inhibiting rate showed the feature of dosage dependence. Inhibitory effect of ASODN and S-ASODN were similar in the same dosage. CONCLUSION: The results suggest that ASODN and S-ASODN can availably inhibit replication and expression of HDV in H1 delta 9 cell.

Hepatitis Delta Virus↗

PubMed1999

Adoptive T-cell immunotherapy of cancer.

Adoptive T-cell therapy involves the passive transfer of antigen-reactive T cells to a tumor-bearing host in order to initiate tumor rejection. Based upon animal models, effector T cells with tumor-specific reactivity are superior to non-specific effector T cells in mediating tumor regression in vivo. Both CD4+ and CD8+ T cells are capable of initiating tumor rejection after adoptive transfer. Several different culture methods have been reported that permit in vitro expansion of immune T cells while retaining tumor specificity. The ability to generate human tumor-specific effector T cells capable of mediating tumor rejection in vivo has provided tools to identify tumor-associated antigens. Future directions in this field involve the selective isolation and expansion of subpopulations of T cells critical to initiating tumor rejection, and the use of molecular techniques to generate effector T cells.

Animals↗

PubMed1999

Reduction of 5-hydroxytryptamine (5-HT)(1A)-mediated temperature and neuroendocrine responses and 5-HT(1A) binding sites in 5-HT transporter knockout mice.

The aim of the present study was to determine whether alterations in 5-hydroxytryptamine (5-HT)(1A) receptors would be found in knockout mice lacking the serotonin transporter (5-HTT). Hypothermic and neuroendocrine responses to the 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)tetraline (8-OH-DPAT) were used to examine the function of 5-HT(1A) receptors. Initial studies evaluated the dose-response and time course of 8-OH-DPAT-induced hypothermia and hormone secretion in normal CD-1 mice (the background strain of the 5-HTT knockout mice). 8-OH-DPAT dose-dependently produced hypothermic responses that peaked at 20 min postinjection. 8-OH-DPAT-induced hypothermia was blocked by the 5-HT(1A) antagonist WAY-100635. 8-OH-DPAT dose-dependently increased the concentrations of plasma oxytocin, corticotropin, and corticosterone. In the 5-HTT knockout (-/-) mice, the hypothermic response to 8-OH-DPAT (0.1 mg/kg s.c.) was completely abolished. Furthermore, 5-HTT-/- mice had significantly attenuated plasma oxytocin and corticosterone responses to 8-OH-DPAT. No significant changes in the hypothermic or hormonal responses to 8-OH-DPAT were observed in heterozygous (5-HTT+/-) mice. [(3)H]8-OH-DPAT- and [(125)I]MPPI [4-(2'-methoxyphenyl)-1-[2'-[N-(2"-pyridinyl)-iodobenzamido]ethyl] pip erazine]-binding sites in the hypothalamus and [(125)I]MPPI-binding sites in the dorsal raphe were significantly decreased in 5-HTT-/- mice. The results indicate that lack of the 5-HTT is associated with a functional desensitization of 5-HT(1A) receptor responses to 8-OH-DPAT, which may be a consequence, at least in part, of the decrease in density of 5-HT(1A) receptors in the hypothalamus and dorsal raphe of 5-HTT-/- mice.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1999

[Gene analysis of acute sporadic HEV in the southern areas of China].

OBJECTIVE: To investigate the existing different gene sequences of hepatitis E virus (HEV) in the southern areas of China. METHODS: Eight acute-phase sera of sporadic patients with hepatitis E in Xiamen were tested by reverse transcription--polymerase chain reaction(RT-PCR). Two cases of them were positive. The fifth passage culture of Guangzhou G93-2 strain of HEV was also detected by RT-PCR. The positive RT-PCR products underwent cloning and nucleotide sequencing. RESULTS: The homology of nucleotide and the amino acid between Xiamen X-S1 and Guangzhou G93-2 strain are 99.2% and 97.5%. The homology of nucleotide and the amino acid sequences of Xiamen strain and Guangzhou strain are 79.9% and 86.3% compared with the Burmese strain (Bur-121) and our country Xinjiang strain (87A), and are 77.4% and 86.3% against Mexican strain. CONCLUSION: The results suggest that there is a different genotype of HEV in the southern areas of China.

Acute Disease↗

PubMed1999

Role of base excision repair in protecting cells from the toxicity of chloroethylnitrosoureas.

The chloroethylnitrosoureas react extensively with cellular DNA to produce a variety of DNA adducts, including a deoxycytidine-deoxyguanosine (dC-dG) cross-link that is clearly cytotoxic. It is now well established that O6-alkylguanine-DNA-alkyltransferase can prevent formation of this dC-dG cross-link and thereby diminish the toxicity of the chloroethylnitrosoureas. Besides alkyltransferase, DNA glycosylases from various species can also contribute to cellular resistance to the chloroethylnitrosoureas, but the mechanism for this increased resistance has not been established. It is known, however, that several chloroethylnitrosoureas-modified DNA bases, including the exocyclic adduct, N2,3-ethanoguanine, are released by Escherichia coli 3-methyladenine DNA glycosylase II. In the study described here, we examined the possibility that this enzyme might act on the exocyclic intermediate in dC-dG formation, 1,O6-ethanodeoxyguanosine, and prevent-dC-dG cross-linking in this way. However, the presence of E. coli 3-methyladenine DNA glycosylase II does not decrease the amount of dC-dG cross-link formed when chloroethylnitrosourea reacts with DNA, and we conclude that this enzyme does not recognize 1,O6-ethanodeoxyguanosine. Therefore, its contribution to resistance probably resides in its action on other nitrosourea-induced DNA modifications.

Chromatography, High Pressure Liquid↗

PubMed1999

[Application of fluorescence insitu hybridization technique for prenatal diagnosis of chromosome abnormality in amniotic cells].

OBJECTIVE: To study the technique and diagnostic value of fluorescence in situ hybridization (FISH) in chromosome abnormality for prenatal diagnosis. METHODS: Amniocenteses were performed in 34 pregnant women of 16-23 gestational weeks with indications for prenatal diagnosis. The amniotic fluid samples were cultured in Chang's medium. The metaphase chromosomes were hybridized in situ with the human centromere probes, alpha-satellites DNA probes of X, Y, 13, 21, 18 chromosomes and all primer chromosome probes. These probes were conjugated by Biotin and Dioxin then. The treated slides were examined and taken photos under the fluoromicroscope. RESULTS: By FISH technique, normal karyotypes were shown in 31 cases: 16 cases of 46, XY, 15 cases of 46, XX. Abnormalities were found in 3 patients which were 47, XY + 21; 47, XY + 18 and 45, X/46, X, r (X) respectively. CONCLUSION: Using FISH technique to detect chromosome abnormalities in amniotic fluid for prenatal diagnosis is a reliable method which is rapid and accurate. It has higher sensitivity and specificity in finding chromosome structure abnormalities and marking chromosome DNA sequences.

Adult↗

PubMed1999

[A study on the T-cell subsets and glucocorticoid receptor in children with anaphylactoid purpura].

To study the changes of T-cell subsets and glucocorticoid receptor (GCR) in children with anaphylactoid purpura. T-cell subsets and GCR were measured respectively by cytotoxicity assay and GCR radioligand-binding assay in peripheral blood lymphocytes from 35 children with anaphylactoid purpura and 35 normal children. The result showed that the average percentages of CD3+, CD4+ cell subtypes and the CD4+/CD3+ ratio were 46.03% +/- 9.40%, 31.06% +/- 6.80% and 1.23 +/- 0.33 respectively, and the GCR numbered 3060 +/- 2153 binding sites per cell in the study group, on the other hand, the average percentages of CD3+, CD4+ cell subtypes and the CD4+/CD3+ ratio were 53.11% +/- 5.40%, 35.01% +/- 4.41% and 1.52 +/- 0.26 respectively, and the GCR numbered 5210 +/- 1639 binding sites per cell in the control group. These indicate that and that patients with anaphylactoid purpura may have abnormal immunomodulations and decreased GCR numbers per cell, which may have effects on the immune dysfunctions in the pathogenesis of anaphylactoid purpura.

Adolescent↗

PubMed1999

[Role of red nucleus in inhibiting nociceptive responses of rat spindle afferent].

Using extracellular recording techniques, the effect of excitation of red nucleus (RN) on C-responses of wide dynamic range (WDR) neurons and the roles of RN in the inhibitory effect of spindle afferent activated by succinycholine (SCH) on C-responses of WDR neurons were studied. Stimulation of RN caused a significant reduction of nociceptive responses of WDR neurons, which was significantly attenuated by intravenous cyproheptadine and contralateral lesion of RN. These results suggest that the inhibitory effect on nociceptive responses of WDR neurons caused by RN stimulation was partly mediated by 5-HT and RN plays an important role in analgesia induced by the muscle spindle afferent activity.

Afferent Pathways↗

PubMed1999

[Diagnosis of sex chromosome abnormality by fluorescence in-situ hybridization].

OBJECTIVE: To evaluate the diagnostic value of fluorescence in-situ hybridization (FISH) in sex chromosome abnormality. METHOD: alpha-satellits DNA probes of X, Y chromosomes were used to FISH with blood samples from 19 patients with primary anemia or of gonad dysplasia. Five infertile men who were detected abnormal by G-banding analysis during metaphase and interphase. Samples from healthy men and women were used as positive controls and reactions with hybridization fluid without probes as negative controls. RESULTS: The karyotypes, 45, X; 45, X/46, XX/47, XXX; 45, X/46, XY; 47, XXY; 45, X/46, XXX were detected by FISH. Others were not detected by G banding such as 45, X/46, X,r? 46, X,r? but were found to be 45, X/46, X,r(X), 46, X, r(X), by FISH technique, confirming to be X ring chromosome. A female patient whose karyotype was 45, X/46, X, mar. by G banding. But G banding technique could not analyze the property of the marker and FISH revealed the marker was dici(yq), that is dicentric chromosome Y with two long arms of equal length. The real karyotype was 45, X/46, X, dici(yq) mosaicism. It belonged to Y chromosome abnormal and gonadal dysplasia syndrome. CONCLUSION: FISH can help to detect those chromosome abnormalities which can not be confirmed by traditional cytogenetics. It is of value in studying the complex chromosome mutation such as sex chromosome abnormality, unknown little marker, ring chromosome, mosaiciasm and translocation.

Adolescent↗

PubMed1999

[Remnant abnormal clonal hematopoiesis in patients with paroxysmal nocturnal hemoglobinuria of clinical remission].

OBJECTIVE: To observe the abnormal clonal hematopoiesis status in patients with paroxysmal nocturnal hemoglobinuria(PNH) attained complete clinical remission(CCR). METHODS: Immunofluorescence labeling and flow cytometry were used to detect the expression of CD59 in bone marrow mononuclear cells and peripheral red blood cell and the number of bone marrow CD34+ hematopoietic stem/progenitor cells. RESULTS: In two patients in CCR, the coexistence of normal and abnormal hematopoiesis could still be found. However, the percentage of normal cells with CD59+ phenotype in peripheral red blood cells, bone marrow mononuclear cells and CD34+ hematopoietic stem/progenitor cells were significantly higher as compared with those in patients without remission, indicating that the normal hematopoiesis gradually regained dominance over the abnormal one when the disease approached remission. CONCLUSIONS: In PNH patients in CCR, remnant abnormal (CD59-) cells could still be found in peripheral blood and bone marrow. It seems not necessary to climinate thoroughly all abnormal clones to achieve CCR in patients with PNH, and the dominance of abnormal hematopoicsis could vanish under some presently unknown mechanism.

Antigens, CD34↗

PubMed1999

A recombinant multi-epitope, multi-stage malaria vaccine candidate expressed in Escherichia coli.

OBJECTIVE: To construct and evaluate a recombinant multi-epitope, multistage malaria vaccine candidate expressed in Escherichia coli (E. coli). METHODS: A hybrid gene (HGF) encoding several putative immunodominant T or T/B epitopes from MSP-1, MSP-2, Pf155/RESA of Plasmodium falciparum (P. falciparum) and two immune-stimulating epitopes from interleukin-1 and tetanus toxin was synthesized. Two copies of HGF and a copy of gene encoding Pattaroyo's Spf66 were connected together to construct a sandwich hybrid gene HGFSP. The gene was cloned into an expression vector pWR450-I for production of a fusion protein with beta-galactosidase. Efficacy of this vaccine candidate in inducing specific immunity against malaria parasites was evaluated. RESULTS: Immunization of different species of animals with purified recombinant peptide showed that the peptide was able to induce remarkable antibody response to the immunized peptide as well as falciparum malaria parasites. The epitopes included in the construct could induce antibodies against the intact parasite proteins as demonstrated by western blotting, indicating the epitopes retained their antigenicity in the new peptide construct. Antibodies from animals immunized with recombinant HGFSP peptide exhibited good ability in inhibition of the in vitro growth of malaria parasites, augmentation of phagocytosis of the parasites or infected RBC by phagocytes, and facilitation of antibody dependent cell mediated cytotoxicity to the cultured malaria parasites. CONCLUSION: The recombinant peptide seems to be a potential candidate which is valuable for further investigation.

Animals↗