Biomedical subjects

Y Ke

Publications and source records attributed to Y Ke.

At least 73 records · Page 4Linked to original sources

PubMed1998

Opium alkaloid noscapine is an antitumor agent that arrests metaphase and induces apoptosis in dividing cells.

An alkaloid from opium, noscapine, is used as an antitussive drug and has low toxicity in humans and mice. We show that noscapine binds stoichiometrically to tubulin, alters its conformation, affects microtubule assembly, and arrests mammalian cells in mitosis. Furthermore, noscapine causes apoptosis in many cell types and has potent antitumor activity against solid murine lymphoid tumors (even when the drug was administered orally) and against human breast and bladder tumors implanted in nude mice. Because noscapine is water-soluble and absorbed after oral administration, its chemotherapeutic potential in human cancer merits thorough evaluation.

Animals↗

PubMed1998

Sodium channel protein expression enhances the invasiveness of rat and human prostate cancer cells.

Expression of Na+ channel protein was analysed in established cell lines of rat and human prostatic carcinoma origin by flow cytometry using a fluorescein-labelled polyclonal antibody. In many cell lines examined, the obtained frequency distribution profiles were bimodal and identified a subpopulation of cells which expressed high levels of Na+ channel protein. A significant positive correlation was demonstrated between the proportion of channel-expressing cells and the functional ability of individual cell lines to invade a basement membrane matrix in vitro. In addition, two transfectant cell lines containing rat prostate cancer genomic DNA were found to express significantly elevated levels of Na+ channel protein when compared with the original benign recipient cell line. Enhanced Na+ channel expression by two metastatic derivatives of these transfectant cells directly correlated with increased invasiveness in vitro. These studies strongly support the hypothesis that expression of Na+ channel protein and the metastatic behaviour of prostatic carcinoma cells are functionally related, either by endowing the membranes of these cells with specialised electrophysiological properties (e.g. enhancing their motility and/or secretory activities) and/or by perturbing endogenous mechanisms regulating ionic homeostasis within the cells.

Animals↗

PubMed1998

Antigen is required for the activation of effector activities, whereas interleukin 2 Is required for the maintenance of memory in ovalbumin-specific, CD8+ cytotoxic T lymphocytes.

The mechanisms that maintain memory in T cells are not completely understood. We have investigated the role of antigen and interleukin (IL)-2 in the growth and maintenance of CD8+ T cells using a cytolytic T cell line specific for ovalbumin (OVA)257-264 presented by H-2Kb. This line does not secrete IL-4 or IL-2; hence, stimulation with the OVA-transfected EL4 line (E.G7-OVA) does not induce proliferation without addition of exogenous growth factors. Furthermore, this line can be maintained continuously by weekly addition of irradiated, splenic filler cells and IL-2, with or without E.G7-OVA. Although IL-2 induced proliferation of these cytotoxic T lymphocytes (CTLs), production of interferon gamma and tumor necrosis factor alpha required stimulation of the CTL with E. G7-OVA. The kinetics of lymphokine secretion after stimulation by E. G7-OVA were the same whether the CTL had been maintained with or without antigen (Ag). In addition, both CTL lines killed E.G7-OVA target cells within 4 h. Thus, the effector functions of these CTLs were rapidly induced by T cell receptor (TCR) occupancy. CTLs cultured with or without Ag also served as memory T cells when parked for 100 d in unirradiated, syngeneic recipients without OVA. In the absence of OVA, the precursor frequency was identical in spleens of normal and beta2-microglobulin knockout recipients, but significantly less in IL-2 knockout mice. The decline of memory in the absence of IL-2 supports data from other investigators, suggesting that cell cycling is important to the maintenance of CD8+ T cell memory. These data also suggest that stimulation of OVA-specific CTLs by lymphokines seems to be more important to maintaining memory than stimulation of TCRs by cross-reactive peptides complexed to class I molecules.

Adoptive Transfer↗

PubMed1998

Equilibrium and kinetics of the folding of equine lysozyme studied by circular dichroism spectroscopy.

The equilibrium unfolding and the kinetics of unfolding and refolding of equine lysozyme, a Ca2+-binding protein, were studied by means of circular dichroism spectra in the far and near-ultraviolet regions. The transition curves of the guanidine hydrochloride-induced unfolding measured at 230 nm and 292.5 nm, and for the apo and holo forms of the protein have shown that the unfolding is well represented by a three-state mechanism in which the molten globule state is populated as a stable intermediate. The molten globule state of this protein is more stable and more native-like than that of alpha-lactalbumin, a homologous protein of equine lysozyme. The kinetic unfolding and refolding of the protein were induced by concentration jumps of the denaturant and measured by stopped-flow circular dichroism. The observed unfolding and refolding curves both agreed well with a single-exponential function. However, in the kinetic refolding reactions below 3 M guanidine hydrochloride, a burst-phase change in the circular dichroism was present, and the burst-phase intermediate in the kinetic refolding is shown to be identical with the molten globule state observed in the equilibrium unfolding. Under a strongly native condition, virtually all the molecules of equine lysozyme transform the structure from the unfolded state into the molten globule, and the subsequent refolding takes place from the molten globule state. The transition state of folding, which may exist between the molten globule and the native states, was characterized by investigating the guanidine hydrochloride concentration-dependence of the rate constants of refolding and unfolding. More than 80% of the hydrophobic surface of the protein is buried in the transition state, so that it is much closer to the native state than to the molten globule in which only 36% of the surface is buried in the interior of the molecule. It is concluded that all the present results are best explained by a sequential model of protein folding, in which the molten globule state is an obligatory folding intermediate on the pathway of folding.

Animals↗

PubMed1998

Flip angle effects in STEAM and PRESS-optimized versus sinc RF pulses.

Flip angle dependence of the localized single-voxel 1H NMR spectroscopic sequences STEAM and PRESS using numerically optimized Shinnar-Le Roux (SLR) and conventional sinc RF pulses has been evaluated. Phantom experiments were used to evaluate voxel profiles from MR images of the selected voxels. Information on the total excited volume was recorded from the integrated area under the water peak in the localized spectrum at different flip angles (theta = 0 degrees-180 degrees). The voxel profiles for both the STEAM and PRESS sequences using the SLR RF pulses were found to be identical, unlike the case for the sinc RF pulses. The SLR RF pulses in the PRESS sequence were found to be more sensitive to flip angle variations. Localized, water-suppressed 1H NMR spectra recorded from the frontal gray matter in healthy volunteers (n = 3) showed less lipid contamination using the SLR RF pulses compared with the sinc RF pulses.

Area Under Curve↗

PubMed1998

Position 120-123, a potential active site of trichosanthin.

Trichosanthin (TCS) is a type-I ribosome-inactivating protein (RIP) with wide spectrum of biological and pharmacological activities. In the present study, a potential site on the TCS molecule (position 120-123) is identified which may be important for the biological activities of TCS. By using site-directed mutagenesis, position 120-123 of TCS was either deleted or changed from Lys-Ile-Arg-Glu (hydrophilic) to Ser-Ala-Gly-Gly (hydrophobic). Deletion of these residues rendered a TCS molecule completely deprived of ribosome inactivating activity, while hydrophobic replacement caused 4000-fold decrease in ribosome inactivating activity. The abortifacient activity of these two mutants was retained with decreased potency. This implies that position 120-123 of the native TCS molecule plays a critical role in maintaining its biological activity.

Abortifacient Agents, Nonsteroidal↗

PubMed1998

Prostatic stromal cell phenotype is directly modulated by norepinephrine.

OBJECTIVES: To evaluate the response of prostatic stromal cells in vitro to the action of the agonist norepinephrine and to examine the role of cell density in this response. METHODS: Stromal cells isolated from transurethral chippings of patients with benign prostatic hyperplasia (BPH) were seeded onto tissue culture dishes either at high density (9 x 10(3) cells/cm2) or at low density (1.5 x 10(3) cells/cm2). Norepinephrine was added at concentrations in the range of 2.5 to 50 microM. Cells were harvested at the moment of confluence, labeled with monoclonal antibodies to four cytoskeletal proteins, and analyzed by flow cytometry. RESULTS: Sparsely plated stromal cells showed a consistent biphasic response in which a small fall in immunofluorescence occurred in the range of 5 to 15 microM norepinephrine but was thereafter followed by a progressive rise in fluorescence to 50 microM, indicating increased expression of smooth-muscle-associated cytoskeletal proteins. The shape of flow-cytometric frequency-distribution histograms for smooth-muscle myosin, desmin, and talin suggested that all mesenchymal cells in the stromal cultures were similarly modulated by norepinephrine. However, the effect on smooth-muscle actin was different in that a subpopulation of hyperreactive cells was identified. Densely plated stromal cells did not show a similar biphasic response to norepinephrine but instead demonstrated an overall downward trend, indicating a progressively diminished expression of these cytoskeletal proteins. CONCLUSIONS: Norepinephrine stimulation directly modulates BPH-derived prostatic stromal cells toward a differentiated smooth-muscle phenotype as evidenced by increased expression of cytoskeletal proteins. The effect of norepinephrine on cultures is cell-density-dependent, suggesting that intercellular communication is an important factor in coordinating the differentiation responses. This study has revealed a specific interaction between physical and humoral stimuli, which influences in part the phenotype of prostatic stromal cells. Such interaction is likely to determine the development of clinical BPH, and also the response of any individuals following therapeutic intervention using selective alpha-adrenergic blockade.

Cell Count↗

PubMed1998

Generation of metastatic variants by transfection of a rat non-metastatic epithelial cell line with genomic DNA from rat prostatic carcinoma cells.

Prostate cancer is the second leading cause of male death from malignant disease in Europe and in the USA. Failure to prevent or eliminate metastatic dissemination is a fundamental problem underlying the current inadequate treatment of prostate cancer, and novel therapeutic strategies are required if this disease is to be successfully managed. No independent markers are yet available to predict the behaviour of any individual prostate cancer, particularly its potential to metastasize, and there is now an urgent prerequisite to identify and characterize genes specifically involved in determining the metastatic phenotype of prostate cancer cells before any biologically appropriate treatment modality can be devised. To identify DNA sequences that trophically promote the metastatic phenotype, we have established a new transfection assay with which to monitor activity of prostate cancer genomic DNA. Rat prostatic G and AT6.1 cell lines derived from the same original Dunning R3327 rat prostatic carcinoma exhibit, respectively, low- and high-metastatic phenotypes when grown in syngeneic Copenhagen rats. Rat mammary epithelial cell line 'Rama 37' derived originally from Wistar-Furth rats yields benign non-metastasizing adenomas when inoculated subcutaneously into syngeneic animals. In this report, the Rama 37 cell line is successfully used as the recipient cell-line for transfected DNA fragments extracted from rat prostatic carcinoma G and AT6.1 cells. New metastatic variants of Rama 37 cells have been generated. Enzymatically fragmented genomic DNA from rat metastatic prostate carcinoma cell lines was co-transfected together with plasmid pSV2neo into parental Rama 37 cells, followed by culture in the presence of Geneticin-G418 to select for the transfected cells. To enable subsequent identification of metastasis-promoting DNA sequences, the fragmented genomic DNA sequences were covalently attached to specifically engineered linker DNA molecules to flank the genomic DNA before transfection. Thereafter, the resulting transfectants were pooled and inoculated into mammary fat pads of female Wistar-Furth rats. Metastases produced by the transfectant cells in vivo were reestablished from secondary tumours and probed for the presence of the specific synthetic oligonucleotide sequences that flanked, and hence identified, the presence of the transfected DNA. These new metastatic cells are shown to provide a sensitive assay system with which to detect DNA sequences responsible for conveying the metastatic phenotype of prostate cancer when inoculated into syngeneic rats.

Animals↗

PubMed1998

Ecto-ATPase: an activation marker necessary for effector cell function.

Ecto-ATPase, a transmembrane enzyme that catalyzes the hydrolysis of extracellular ATP (ATPe) to ADP and inorganic phosphate, is expressed upon cell activation. Ecto-ATPase is inhibited by non-hydrolyzable ATP analogues, which are competitive inhibitors of the catalytic reaction, and the ATP analogue affinity label. 5'-p-(fluorosulfonyl)benzoyl adenosine (5'-FSBA), which irreversibly inhibits the catalytic activity. These nucleotide antagonists do not cross the cell membrane and are specific for ecto-ATPase in T cells, B cells and NK cells. Inhibition of ecto-ATPase by both reversible and irreversible nucleotide antagonists results in the inhibition of antigen-induced cytokine secretion and cytolytic activity of T cells. Likewise, granule release and cytolytic activity of NK cells as well as antibody secretion and spontaneous proliferation by B-cell hybridomas are inhibited. Inhibition of ecto-ATPase does not influence effector cell-target cell conjugate formation, but acts, in part, by regulating the influx of extracellular calcium that is necessary to maintain cellular activation. Thus, further elucidation of ecto-ATPase regulation and expression and its interaction with intracellular signal transduction events will provide a basis for understanding the role of the hydrolysis of ATPe by ecto-ATPase in lymphocyte effector function.

Adenosine Triphosphatases↗

PubMed1998

Cerebral 1H MR spectroscopy and neuropsychologic status of patients with hepatic encephalopathy.

OBJECTIVE: Our objective was to assess the metabolite levels (myo-inositol [ml], choline [Cho], creatine [Cr], glutamate or glutamine [Glx], and N-acetyl-L-aspartate [NAA]) visible on 1H MR spectroscopy in patients with subclinical and mild hepatic encephalopathy before and after liver transplantation and to correlate these data with the results of neuropsychiatric tests and related clinical findings. SUBJECTS AND METHODS: A stimulated-echo sequence was used to localize a single voxel in the parietal region. Seventeen patients and 13 healthy volunteers were investigated. Nine of the 17 patients also were investigated after liver transplantation. A battery of neuropsychologic tests also was administered to patients to assess frontal, memory, and motor functions. RESULTS: Before liver transplantation, significant reductions in mI:Cr (51%) and Cho:Cr (11%) and a significant increase in Glx:Cr (20%) were observed in patients compared with the respective ratios in healthy subjects. Patients also were significantly impaired on neuropsychologic tests measuring frontal and motor performance, but not memory. Impairment on the frontal index showed a significant correlation with mI:Cr levels; likewise, performance on the motor index showed a significant correlation with serum ammonia levels before transplantation. MR spectroscopy after liver transplantation showed changes in the metabolite ratios compared with the pretransplantation status. Even though the Glx:Cr ratios decreased after transplantation, the mI:Cr ratio remained lower than those of healthy subjects. CONCLUSION: The relationship of changes in the metabolite ratios recorded from a voxel in the posteromedial parietal lobe to the neuropsychologic findings before and after liver transplantation is a major finding.

Adult↗

PubMed1998

[Studies of loss of heterozygosity(LOH) in Chinese human gastric cancer tissues].

OBJECTIVE: To identify the LOH frequency in Chinese gastric cancer samples and locate lost region of gastric cancer-related tumor suppressor gene. METHODS: Thirty microsatellite markers were used to examine 42 cases of tumor-normal paired gastric cancer tissues for LOH on all chromosomes (except Y) using polymerase chain reaction(PCR). RESULTS: The total frequency of LOH in 42 gastric cancer was 27.7%. High frequencies of LOH (> or = 40%) were observed at loci D3S1067, D3S1577, D6S430, D15S205, D17S945, and D5S407, D2S136, D2S147, D13S175, D14S68, D8S279 loci had LOH frequency > or = 30%. Significantly more LOH cases were observed in the poorly differentiated type and the signet-cell type than in well differentiated type of gastric cancers (P = 0.00699 and 0.0001). The incidence of LOH in signet-cell cancer was even significantly higher than that in poorly differentiated gastric carcinomas(P = 0.0019). LOH was not found in 4 cases with well differentiated gastric cancer. CONCLUSION: The most common LOH occurred at D3S1577, D3S1067, D5S407, D6S430, D8S279, D15S205 and D17S945 might imply the existence of potential tumor suppressor genes of gastric cancer.

Adenocarcinoma↗

PubMed1998

[Angiographic observation of immediate effect of electric pulse stimulation at Zhiyang point on coronary artery].

OBJECTIVE: To evaluate angiographical diameter and pressure changes of coronary artery and heart rate in patients with coronary heart disease (CHD) or suspected CHD immediately after electric pulse stimulation of Zhiyang (Du. 9) point. METHODS: Twenty-four patients including 21 males and 3 females with an average age of 48.7 years. Parameters of electric pulse stimulation were as follows: the positive pulse range was 440 V, the negative pulse range was 160 V, the cycle was 8 ms, frequency was 125 Hz, the positive pulse width was 0.8 ms, the negative was 0.4 ms, and the output voltage 9 V. Coronary arteriography was performed by using Judkins technique, and intracoronary pressure with heart rate and any response of patients to the stimulation were recorded pre- and post-stimulation for 90 seconds. The relative diameter of left main coronary artery (LMCA), left anterior descending artery (LAD), left circumflex coronary artery (LCx), and right coronary artery (RCA) before and after the stimulation was measured in the same magnification and their results with recordings of intracoronary pressure and heart rate was analyzed. RESULTS: A mild dilation effect was observed in all coronary arteries with an average dilation of 8.3% (6.3%-15%) in LMCA, 7.7% (5%-11.8%) in LAD, 8.5% (6.7%-11.1%) in LCx, and 9.1% (6.1%-13.3%) in RCA. No significant difference was found in the change of the diameter of LMCA, LAD, LCx and RCA before and after the stimulation and between them. No significant change of an intracoronary pressure was shown in three patients, an increase of intracoronary systolic and diastolic pressure by 36% and 13% was identified in one, and a decrease by 21% and 31% in another patient. Heart rate was decreased by 2.3% in those five patients. CONCLUSIONS: Electric pulse stimulation of Zhiyang point could immediately produce mild dilation effect on coronary arteries, slight decrease on the heart rate, and different effects was produced in intracoronary pressure.

Acupuncture Points↗

PubMed1998

Use of DNA transfer in the induction of metastasis in experimental mammary systems.

The metastatic spread of cancer is a little understood process, in part because it is difficult to model the entire process using experimental approaches in vitro. The ability to transfer DNA into non-metastatic mammary cells and to observe the induction of metastasis in vivo provides a means for identifying DNA sequences that are associated with the development of metastatic capability. Using these techniques, a metastasis-associated cytoskeletal calcium binding protein, S100A4 (p9Ka), has been identified as an inducer of metastatic capability in benign rat mammary epithelial cells. Metastasis can also be induced in the rat mammary epithelial cells by fragments of DNA from metastatic, but not from benign, human breast tumour cells. These non-coding fragments of DNA act via the induction of osteopontin, an extracellular, integrin binding, calcium binding protein. Since both osteopontin and S100A4 are thought to be associated with malignancy in human breast cancer specimens, gene transfer techniques can identify genes for metastasis-inducing proteins that may play a role in breast cancer, and further suggest that cell migration/motility might be important in the metastatic process.

Animals↗

PubMed1998

Proton MR spectroscopy in Lesch-Nyhan disease.

In vivo proton spectra for four patients with Lesch-Nyhan disease and four control subjects matched for age and sex were acquired from voxels (1.5 x 1.5 x 1.5 cm3) placed in the prefrontal cortex and striatum. The patients with Lesch-Nyhan disease had decreased metabolites, especially N-acetylaspartate and glutamate/glutamine, only in the prefrontal cortex as compared with the control group. These findings suggest axonal loss in the prefrontal area of this population. The cortical glutamate/glutamine peak decrement does not confirm cytopathologic studies of Lesch-Nyhan disease and deserves further investigation.

Adolescent↗

PubMed1997

Fourier-transform infrared spectroscopic studies on the coordination of the side-chain COO- groups to Ca2+ in equine lysozyme.

Interactions between Ca2+ and the Asp side chains in the Ca2+-binding site of equine lysozyme were investigated by Fourier-transform infrared (FT-IR) spectroscopy. In the spectrum of equine lysozyme, the intensities of the bands at about 1595 cm-1 and 1578 cm-1 in the region of the COO antisymmetric stretches increased upon Ca2+ binding. In the region of the COO- symmetric stretches, the loss of intensity at about 1388 cm-1 and gains of intensities at about 1423 cm-1 and 1403 cm-1 were observed due to Ca2+ binding to equine lysozyme. The spectral changes for equine lysozyme indicate that the COO- groups of Asp85, Asp90 and Asp91 in the Ca2+-binding site coordinate to Ca2+ in the pseudo-bridging mode, where divalent metal cation is bound to one of the two oxygens in the COO- group and a water molecule is hydrogen bonded to the other oxygen. The results presented here provide further evidence for a high degree of similarity between Ca2+-binding lysozyme and alpha-lactalbumin. The effects of Ca2+ binding on the main-chain conformation of equine lysozyme were compared with those of bovine alpha-lactalbumin and hen egg-white lysozyme.

Animals↗

PubMed1997

Elevated expression of calcium-binding protein p9Ka is associated with increasing malignant characteristics of rat prostate carcinoma cells.

Northern and Western blotting techniques were used to study expression of the mRNA and corresponding protein product of the S100-related calcium-binding molecule p9Ka in 6 different metastatic cell lines of the Dunning R3327 rat prostate cancer model. In cells with the lowest metastatic capability (G cells), p9Ka mRNA was barely detectable. In 2 weakly metastatic cell lines (AT-1 and AT-2), p9Ka transcript amounts were, respectively, 6.29 +/- 0.74 and 5.55 +/- 1.11 times that detected in the G cells. In 3 highly metastatic cell lines (AT-3, MAT-LyLu and MAT-Lu), the amounts of p9Ka mRNA were, respectively, 12.85 +/- 2.82, 13.06 +/- 1.69 and 11.62 +/- 1.81 times that expressed in the G cells. Western blot analyses detected no p9Ka protein in the G cells. The amounts of p9Ka protein expressed by tumour cells of intermediate metastatic capability (AT-1 and AT-2) were 3.4 +/- 1.3 microg and 3.3 +/- 1.4 microg, respectively, per 1 x 10(6) cells. The amounts of p9Ka protein expressed by the tumour cells of highest metastatic capability (AT-3, MAT-LyLu and MAT-Lu) were 8.3 +/- 1.1 microg, 8.7 +/- 1.6 microg and 9.6 +/- 1.7 microg, respectively, per 1 x 10(6) cells. Our data reveal a direct association between the elevated expression of mRNA and the p9Ka protein amounts and the increased metastatic capability of individual prostatic cancer cell lines. We suggest that calcium-binding protein p9Ka may play an important role in the metastatic behaviour of rat prostate cancer.

Animals↗

PubMed1997

Gamma delta T lymphocytes regulate the induction and maintenance of oral tolerance.

Oral administration of Ag, over a period of several days, induces a state of tolerance that is associated with activation of CD8+ T cells that can transfer unresponsiveness to naive syngeneic hosts. We previously demonstrated that these T cells are not CTL precursors and that they inhibit responses by CD8+ CTL, as well as Ab and CD4+ T cell responses. Activation of noncytolytic, CD8+ suppressor T cells by oral Ag is a process that is not understood. In these studies, we asked whether depletion of the gamma delta T cells altered induction of oral tolerance. Injection of the anti-delta-chain Ab (GL3) down-modulated the expression of gamma delta TCR and inhibited the induction of oral tolerance to OVA, as measured by Ab, CD4+, and CD8+ T cell responses. GL3 did not activate IL-2 secretion that could be detected in the serum, nor did it induce IL-2R expression by intraepithelial lymphocytes, suggesting that GL3 inhibited the function of gamma delta T cells rather than activating them. This interpretation is supported by our observation that oral administration of Ag did not induce tolerance in TCR-delta knockout mice. These data suggest that gamma delta T cells play a critical, active role in tolerance induced by orally administered Ag.

Animals↗

PubMed1997

FHIT mutations in human primary gastric cancer.

Allelic deletion of multiple regions on the short arm of chromosome 3 (3p) implies the presence of multiple important tumor suppressor genes in human carcinogenesis. The FHIT gene, identified recently in chromosome 3p14.2, shows frequent allelic deletion and aberrant transcripts in gastrointestinal tumors. After determining the intron sequences flanking each of the coding exons of the FHIT gene and designing intron primers to facilitate mutation analysis of genomic DNA samples, we analyzed the complete coding sequences in matched cancer and normal tissues from 40 cases with primary gastric cancer using intron primers, PCR-single-strand conformation polymorphism analysis, and direct sequencing. A somatic missense mutation in exon 6, codon 61, ACG (threonine) --> ATG (methionine) was found in a signet ring cell adenocarcinoma. We also evaluated allelic deletion in these tumors by PCR-based microsatellite analysis; allelic deletion occurred in 42.1% (16 of 38) of evaluable cases. This is the first report of a somatic missense mutation of the FHIT gene in a primary tumor. Presence of a point mutation and frequent allelic deletions are consistent with the hypothesis that FHIT gene alterations are involved in the development of primary gastric cancers.

Acid Anhydride Hydrolases↗