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H Li

Publications and source records attributed to H Li.

At least 541 records · Page 30Linked to original sources
PubMed2000

Synthesis, conformational analysis and bioactivity of Lan-7, a lanthionine analog of TT-232.

A sandostatin analog, TT-232 (D-Phe-c[Cys-Tyr-D-Trp-Lys-Cys]-Thr-NH2), exhibits strong antitumor effects both in vitro and in vivo. In order to study the structure-activity relationships of TT-232, we designed and synthesized an analog of TT-232, namely Lan-7, in which the disulfide bridge is replaced by a lanthionine monosulfide bridge. Conformational analysis by NMR spectroscopy and computer simulations revealed that Lan-7 and TT-232 adopt very similar conformations in solution, which are quite different from the preferred conformations of sandostatin. Lan-7 has significant growth inhibition effects on a number of human tumor cell lines. It can also induce apoptosis in human ovarian carcinoma 2008 cells. At the same time, Lan-7 produced no toxicity to normal human hematopoietic progenitor cells. All of these results indicate that the modification we made does not alter the anti-tumor activity of TT-232.

Antineoplastic Agents↗
PubMed2000

A general test of association for complex diseases with variable age of onset.

Analysis of age of onset is a key factor in linkage and association studies of some complex genetic traits. Recent methodological developments are mainly concentrated on binary or quantitative traits, in which age of onset information is ignored. We propose a linkage disequilibrium-based Cox model and a robust score test for testing association between a marker and a disease with variable age of onset. The proposed model is semi-parametric, with an unspecified baseline hazard function. Simulation results indicate that the proposed methods have correct error rates and good statistical power, even in the presence of population admixture. This approach offers a solution to the problem of testing for marker associations when there is a variable age of onset.

Age of Onset↗
PubMed2000

Role for interferon-gamma in rat strains with different susceptibility to experimental autoimmune myasthenia gravis.

Experimental autoimmune myasthenia gravis (EAMG) is caused by autoantibodies against the nicotinic acetylcholine receptor (AChR) at the neuromuscular postsynaptic membrane and represents an animal model of myasthenia gravis in human. Recent studies highlighted the roles of TH1 cytokines (IFN-gamma, IL-12), rather than TH2 cytokines (IL-4), in the pathogenesis of EAMG by using homozygous (-/-) knockout mice with an EAMG-susceptible genetic background. To further evaluate a role for IFN-gamma, we injected recombinant rat IFN-gamma (rrIFN-gamma) at the time of immunization with AChR in complete Freund's adjuvant to EAMG-susceptible Lewis rats and EAMG-resistant Wistar Furth (WF) rats. RrIFN-gamma enhanced Lewis rat EAMG. The exacerbated muscular weakness was associated with higher levels of anti-AChR IgG and enhanced TNF-alpha responses. Anti-AChR IgG antibody levels were augmented to a similar extent as in Lewis rats, however, the identical immunization and IFN-gamma injection induced only mild and transient EAMG in WF rats due to the default TH3 phenotype development and inherent low TH1 responses. We conclude that IFN-gamma plays a major role in the pathogenesis of EAMG in the Lewis rat, but fails to break disease resistance in the WF rat.

Animals↗
PubMed2000

Fish uptake of inorganic and mucus complexes of lead.

Carassius auratus were exposed to lead in synthetic water. Mucus secreted from the fish was measured and characterized for its lead binding capacity. The increase in mucus concentration in the water depended on secretion and degradation rates and the former was speeded up by lead. The complexation between mucus and lead can be described based on a single-site interaction model. Lead speciation in the system with or without mucus was calculated using chemical equilibrium modeling. The dominant species of lead was PbCO(3)(0). Other major species included Pb(OH)(+), Pb(OH)(2)(0), Pb(CO(3))(2)(2-), Pb-mucus, and Pb(2+), among which free lead and lead hydroxo complexes were available to fish uptake.

Animals↗
PubMed2000

Molecular and cytokinetic pretreatment risk assessment in endometrial carcinoma.

OBJECTIVE: Our objective was to determine whether cytokinetic and molecular analyses of curettage specimens can provide a mechanism for triage of patients with endometrial cancer before initiating definitive surgical treatment. METHODS: Pretreatment analysis consisted of flow cytometric determination of ploidy, S-phase fraction (SPF), and proliferative index (PI) and immunohistochemical determination of expression of proliferating cell nuclear antigen, HER-2/neu, and p53 in curettage specimens from 134 patients with endometrial carcinoma who subsequently had surgical staging and definitive surgical treatment. Fisher's exact test or chi(2) was used to examine the association between pretreatment variables and traditional surgical-pathologic indices. The log-rank test was used for univariate survival analysis. Cox proportional hazards identified the most important molecular factors. RESULTS: Nondiploid status, SPF >/=9%, and PI >/=14% were associated with the traditional posttreatment prognostic indices, stage, grade, and histologic subtype. Univariate survival analysis demonstrated a correlation between nondiploid status, SPF >/=9%, PI >/=14%, and p53 overexpression and decreased progression-free survival (PFS) and disease-related survival (DRS). Stepwise Cox regression analysis identified p53 overexpression and SPF >/=9% as the most significant pretreatment molecular risk factors. A model stratifying patients according to whether none, one, or both of these two pretreatment factors were present showed that when both factors are present the risk for recurrence was higher (RR = 7.07; 95% confidence interval [CI], 3.06-16.38; P < 0.01) and death due to disease was higher (RR = 9.93; 95% CI, 3.92-25.19; P < 0.01) than when no factors are present. In the group with both factors, 5-year PFS and DRS estimates were 41 and 44%, respectively, compared with 86 and 86% and 90 and 92% for the "none" and "one" groups, respectively. CONCLUSION: When observed simultaneously, increased SPF and p53 overexpression defined a group of patients at high risk for rapid recurrence and death due to disease. Pretreatment molecular analysis of curettage specimens could provide a mechanism of triage that could be applied before definitive surgical treatment.

Adult↗
PubMed2000

Hyperestrogenism: a relevant risk factor for the development of cancer from endometriosis.

OBJECTIVE: Endometriosis is extremely common in developed countries. Obesity is a major health concern and may cause hyperestrogenism. Hormonal replacement, particularly unopposed estrogens after hysterectomy, is becoming popular. Because endometriosis is ectopic endometrium, hyperestrogenism (either endogenous or exogenous) may cause hyperplasia or transformation into cancer. This study was conducted to describe the main clinical and pathologic features of malignancies in endometriosis and define the treatment and outcome and to compare patients who had cancer arising in endometriosis with patients who had endometriosis but no cancer. METHODS: Patients who had tumors from endometriosis diagnosed from 1986 to 1997 were analyzed retrospectively. Each patient was matched with two control patients (endometriosis without cancer) treated during the same study interval. Clinical and epidemiologic variables were compared to identify risk factors for the development of cancer. RESULT: We identified 31 patients with cancer developing from endometriosis. Fifteen women were obese, 9 had a history of endometriosis, and 9 were taking unopposed estrogen. Endometrioid adenocarcinoma was the most common histologic type (16 patients). When the patients with cancer were compared with controls, no significantly higher risk for the development of cancer was found with prolonged use of unopposed estrogens or with higher body mass index, but a trend was observed. When obesity and use of unopposed estrogens were considered together, the difference was statistically significant (P = 0.05). CONCLUSION: Hyperestrogenism, either endogenous or exogenous, is a significant risk factor for the development of cancer from endometriosis. The prevalences of endometriosis, obesity, and use of hormonal replacement therapy in women in developed countries are increasing, and this trend justifies the assumption that cancer developing in endometriosis might become more common in the future.

Adenocarcinoma, Clear Cell↗
PubMed2000

Characterization of the Ground State of Br(2) by Laser-Induced Fluorescence Fourier Transform Spectroscopy of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) System.

The laser-induced fluorescence (LIF) spectrum of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) system of Br(2) was recorded by Fourier transform spectroscopy (FTS). The LIF spectra were obtained by using continuous-wave dye laser excitation in the spectral region 16 800-18 000 cm(-1). About 1800 rotationally resolved lines were recorded in 96 fluorescence progressions, originating from the 10 </= v' </= 22 vibrational levels of the B(3)Pi(0(+))(u) state and involving the 2 </= v" </= 29 levels of the X(1)Sigma(+)(g) ground state of the three isotopomers of bromine, (79)Br(2), (81)Br(2), and (79,81)Br(2). These data, together with (79)Br(2) data from a previous FTS absorption study [S. Gerstenkorn, P. Luc, A. Raynal, and J. Sinzelle, J. Phys. (France) 48, 1685-1696 (1987)], were analyzed to yield improved Dunham constants for the ground state. A Rydberg-Klein-Rees (RKR) potential energy curve was computed for the X(1)Sigma(+)(g) state (v" = 0-29). The equilibrium bond length was found to be R(e)(X(1)Sigma(+)(g)) = 2.2810213(20) Å. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Fourier Transform Spectroscopy of Chemiluminescence from the SrO A(1)Sigma(+)-X(1)Sigma(+) Transition.

The A(1)Sigma(+)-X(1)Sigma(+) chemiluminescence spectrum of SrO was observed using a Fourier transform spectrometer. SrO was produced in a Broida-type oven from the Sr + N(2)O reaction. A total of 75 bands from (88)SrO, (87)SrO, and (86)SrO were measured in the range of 7600-13 600 cm(-1) at a resolution of 0.04 cm(-1). The vibrational levels of the ground state were observed up to v" = 12 and over 10 000 rovibrational lines with J as high as 153 were analyzed at a precision of about 0.005 cm(-1). Significantly improved spectral constants for the ground state were obtained by representing the perturbed excited state by term values and by adding the known microwave data and infrared data to our fit. Strong perturbations were observed in the upper A state. The vibrational levels of the A(1)Sigma(+) state were measured up to v' = 8 and some new perturbations are reported. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Expression of huntingtin-associated protein-1 in neuronal cells implicates a role in neuritic growth.

Huntingtin-associated protein-1 (HAP1) binds more tightly to mutant huntingtin, but its function and distribution in neurites are not clear. Using PC12 cells and cultured hippocampal neurons, we found that two HAP1 isoforms, HAP1-A and HAP1-B, have different subcellular localizations. While most HAP1-B is diffusely distributed within the cytoplasm, HAP1-A is enriched in the growth cones and neuritic puncta of developing neurons. In mature neurons and adult brain neurons, however, HAP1-A is concentrated in axon terminals and associated with synaptic vesicles. Transfection of HAP1-A in PC12 cells significantly promotes neurite extension, with HAP1-A distributed in the distal regions of the growing neurites. Cotransfection of mutant huntingtin with HAP1-A in PC12 cells results in the accumulation of HAP1-A on huntingtin aggregates and the inhibition of neurite promotion by HAP1-A. This study suggests that HAP1-A has a function in neuritic development and synaptic function and that mutant huntingtin may alter this function.

Amino Acid Sequence↗
PubMed2000

Study on P16 gene in acute leukemia.

To study the change of suppressing cancer gene P16 in acute leukemia, the P16 antigen expression of leukemia cell surfaces in 61 cases were investigated with ABC assay and gene structural defects in 51 cases of acute leukemia were examined with multiple comparative PCR method. It was found that antigen expression of P16 in leukemia was obviously lower than that innormal subjects (P < 0.001). At the same time, antigen expression in All was lower than that AML (P < 0.05). No significant difference was found between the complete remission (CR) and non-remission (NR) subjects from AML and ALL groups (P > 0.05). THe exon 2 of P16 gene showed homozygous deletion only inn 4 cases out of 30 cases in ALL. No structural defect was revealed in 21 cases of AML. It was suggested that expression defect of P16 gene was a main cause in development and progression of acute leukemia, and structural defect of exon 2 was not a primary molecular event.

Adolescent↗
PubMed2000

The effect of estrogen on the restoration of bone mass and bone quality in ovariectomized rats.

To evaluate the effect of estrogen on its ability to restore the bone mass and bone quality in ovariectomized rats by examining the changes of bone morphology and histomorphometry, 3-month-old rats were divided randomly into 4 groups: normal control, ovariectomized (OVX), sham-operated (Sham-O) and OVX plus estrogen (OVX + E2). Treatment initiated from the day 8 weeks after operation and continued for 12 weeks. Bone morphology and histomorphometry were examined afterwards. Results showed that comparing to control group, the trabecular bone in OVX appeared thinner and reduced in the amount. The connectivity between trabecula was decreased and the structure disordered. The free-end of trabecula was increased. The cavity of bone marrow enlarged. After treatment with estrogen, above changes improved remarkably by different degree, although did not reach the normal face. The bone histomorphometry results demonstrated that estrogen treatment increased bone mass and the amount of trabecula by 129% and 132% respectively (P < 0.05). The activity of bone resorption decreased significantly and the rate of bone formation increased to 203%. These results suggest that treatment of ovariectomized rats with estrogen can not only increase bone mass, also improve the bone structure and enhance the property of bone mechanics.

Animals↗
PubMed2000

Determination of idarubicin in human urine by capillary zone electrophoresis with amperometric detection.

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection, has been developed for the determination of idarubicin in human urine. A carbon disk electrode was used as working electrode. The optimal conditions of separation and detection were pH 5.6 phosphate buffer (0.20 mol/L), 22 kV for the separation voltage and 1.00 V (vs. Ag/AgCl, 3 mol/L KCl) for the detection potential. The linear range was from 4.0 x 10(-7) to 2.0 x 10(-5) mol/L with a regression coefficient of 0.9986, and the detection limit was 8.0 x 10(-8) mol/L. The method was directly applied to the determination of idarubicin in spiked human urine without any other sample pretreatment except filtration, and the assay results were satisfactory.

Antibiotics, Antineoplastic↗
PubMed2000

Human cytotoxic T-lymphocyte responses specific for peptides of the wild-type Wilms' tumor gene (WT1 ) product.

The product of the Wilms' tumor gene WT1 is a transcription factor overexpressed not only in leukemic blast cells of almost all patients with acute myeloid leukemia, acute lymphoid leukemia, and chronic myeloid leukemia, but also in various types of solid tumor cells. Thus, it is suggested that the WT1 gene plays an important role in both leukemogenesis and tumorigenesis. Here we tested the potential of WT1 to serve as a target for immunotherapy against leukemia and solid tumors. Four 9-mer WT1 peptides that contain HLA-A2.1-binding anchor motifs were synthesized. Two of them, Db126 and WH187, were determined to bind to HLA-A2.1 molecules in a binding assay using transporter associated with antigen processing-deficient T2 cells. Peripheral blood mononuclear cells from an HLA-A2.1-positive healthy donor were repeatedly sensitized in vitro with T2 cells pulsed with each of these two WT1 peptides, and CD8(+) cytotoxic T lymphocytes (CTLs) that specifically lyse WT1 peptide-pulsed T2 cells in an HLA-A2.1-restricted fashion were induced. The CTLs also exerted specific lysis against WT1-expressing, HLA-A2.1-positive leukemia cells, but not against WT1-expressing, HLA-A2.1-negative leukemia cells, or WT1-nonexpressing, HLA-A2. 1-positive B-lymphoblastoid cells. These data provide the first evidence of human CTL responses specific for the WT1 peptides, and provide a rationale for developing WT1 peptide-based adoptive T-cell therapy and vaccination against leukemia and solid tumors.

CD3 Complex↗
PubMed2000

Phosphorylation is required for high-affinity binding of DBP, a yeast mitochondrial site-specific RNA binding protein.

All yeast mitochondrial mRNAs terminate at their 3' ends with a conserved dodecamer sequence, a site for high-affinity binding by DBP (dodecamer binding protein). Using purified DBP, we show that binding requires an intact dodecamer site and is enhanced by the presence in an oligonucleotide of the immediate 4-5 upstream nucleotides. Binding affinity varied from 0.25 to 0.85 nM towards a set of RNA oligonucleotides containing messenger specific upstream sequences in addition to the dodecamer site. Furthermore, we show that phosphatase treatment of DBP abolishes its specific binding, indicating the involvement of reversible phosphorylation in the regulation of its binding activities. This finding will further our understanding of the mechanism of DBP in the regulation of RNA metabolism in yeast mitochondria.

Base Sequence↗
PubMed2000

A simple and accurate method for determination of microsatellite total allele content differences between DNA pools.

DNA pooling is a potential tool for the efficient analysis of the large numbers of samples and DNA markers that are necessary for genome-wide association studies. A simple accurate method for measuring total allele differences in comparisons between two pools containing large numbers of DNA samples is presented. This method compares relative peak height differences between electrophoretograms for each allele of a microsatellite. The method was evaluated by the analysis of 11 microsatellite markers and DNA pooled sample sizes of 50, 100, and 200 individual DNA samples from the same number of different subjects. Pools were created from previously individually genotyped subjects and constructed so that the pool comparisons would provide real total allele differences varying from 0% to 55%. Calculated pool differences were then compared with the real total allele differences determined by individual genotyping results. Together over 200 comparisons demonstrated a correlation coefficient of 0.96, which compared favorably with other previous methods of analysis. This method could provide a rapid screen for total allele differences of greater than 10%, a threshold that should be applicable to detecting low relative risk genes in common diseases. Therefore, these studies suggest that DNA pooling could be a useful tool in association studies for the determination of candidate regions for a range of complex genetic diseases.

Alleles↗
PubMed2000

Oxidative metabolites of 5-S-cysteinyldopamine inhibit the alpha-ketoglutarate dehydrogenase complex: possible relevance to the pathogenesis of Parkinson's disease.

A characteristic change in the substantia nigra of Parkinson's disease patients is an apparent accelerated rate of dopamine oxidation as evidenced by an increased 5-S-cysteinyldopamine (5-S-CyS-DA) to dopamine ratio. However, 5-S-CyS-DA is more easily oxidized than dopamine to give 7-(2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothiazine-3-carboxylic acid (DHBT-1). Previous studies have demonstrated that DHBT-1 can be accumulated by intact rat brain mitochondria and inhibits complex I but not complex II respiration. In this study, it is shown that DHBT-1 also inhibits the alpha-ketoglutarate dehydrogenase complex (alpha-KGDH) but not cytochrome c oxidase (complex IV). The inhibition of alpha-KGDH is dependent on the oxidation of DHBT-1, catalyzed by an unknown constituent of the inner mitochondrial membrane, to an electrophilic o-quinone imine that covalently modifies active site sulfhydryl residues. The latter conclusion is based on the ability of > or = equimolar glutathione to block the inhibition of alpha-KGDH by DHBT-1, without altering its rate of mitochondrial membrane-catalyzed oxidation, by scavenging the electrophilic o-quinone intermediate forming glutathionyl conjugates which have been isolated and spectroscopically characterized. Activities of mitochondrial alpha-KGDH and complex I, but not other respiratory complexes, are decreased in the parkinsonian substantia nigra. Such changes together with evidence for accelerated dopamine oxidation, increased formation of 5-S-CyS-DA and the ease of oxidation of this conjugate to DHBT-1 which inhibits alpha-KGDH and complex I, without affecting other respiratory enzyme complexes, suggests that the latter putative metabolite might be an endotoxin that contributes to the alpha-KGDH and complex I defects in Parkinson's disease.

Animals↗
PubMed2000

Bradykinin protects the rabbit heart after cardioplegic ischemia via NO-dependent pathways.

BACKGROUND: Depressed myocardial performance is an important clinical problem after open heart surgery. We hypothesized pretreating with bradykinin would pharmacologically precondition the heart and improve post-ischemic performance, and induce myocardial preconditioning by activating nitric oxide synthase. METHODS: Thirty-three rabbit hearts underwent retrograde perfusion with Krebs-Henseleit buffer (KHB) followed by 50 minutes of 37 degrees C cardioplegic ischemia with St. Thomas' cardioplegia solution (StTCP). Ten control hearts received no pretreatment. Ten bradykinin-pretreated hearts received a 10-minute infusion of 0.1 microMol/L bradykinin-enriched KHB and cardioplegic arrest with 0.1 microMol/L bradykinin-enriched StTCP. Six other hearts received 0.1 microMol/L HOE 140, a selective B2 receptor antagonist, added to both the 0.1 microMol/L bradykinin-enriched KHB and 0.1 microMol/L bradykinin-enriched StTCP solutions. Finally, six other hearts received 100 microMol/L of N-omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase, added to both the 0.1 microMol/L bradykinin-enriched KHB and 0.1 microMol/L bradykinin-enriched StTCP solutions. RESULTS: Bradykinin pretreatment significantly improved postischemic performance and coronary flow (CF) compared with control (LVDP: 53 +/- 5* vs 27 +/- 4 mm Hg; +dP/dtmax: 1,025 +/- 93* vs 507 +/- 85 mm Hg/s; CF: 31 +/- 3* vs 22 +/- 2 mL/min; *p < 0.05). Both HOE 140 and L-NAME abolished bradykinin-induced protection, resulting in recovery equivalent to untreated controls. CONCLUSIONS: Bradykinin pretreatment improves recovery of ventricular and coronary vascular function via nitric oxide-dependent mechanisms. Pharmacologic preconditioning by bradykinin pretreatment may be an important new strategy for improving myocardial protection during heart surgery.

Animals↗