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Biomedical subjects

J Liao

Publications and source records attributed to J Liao.

At least 91 records · Page 5Linked to original sources
PubMed1997

Specific inhibition of Stat3 signal transduction by PIAS3.

The signal transducer and activator of transcription-3 (Stat3) protein is activated by the interleukin 6 (IL-6) family of cytokines, epidermal growth factor, and leptin. A protein named PIAS3 (protein inhibitor of activated STAT) that binds to Stat3 was isolated and characterized. The association of PIAS3 with Stat3 in vivo was only observed in cells stimulated with ligands that cause the activation of Stat3. PIAS3 blocked the DNA-binding activity of Stat3 and inhibited Stat3-mediated gene activation. Although Stat1 is also phosphorylated in response to IL-6, PIAS3 did not interact with Stat1 or affect its DNA-binding or transcriptional activity. The results indicate that PIAS3 is a specific inhibitor of Stat3.

Amino Acid Sequence↗
PubMed1997

Association of glucose-regulated protein (grp78) with human keratin 8.

Keratin polypeptides 8 and 18 (K8/18) are intermediate filament proteins that are expressed in 'simple-type' epithelial cells. They associate with several proteins including the 70 kDa cytoplasmic heat shock proteins (hsp70). We identified the human 78 kDa glucose-regulated protein (grp78) as a keratin-associated protein. Keratin-grp78 association was noted after co-immunoprecipitation of K8/18 from HT29 detergent solubilized cell lysates, and appears to involve non-posttranslationally modified grp78. The grp78-K8/18 association is induced by culturing cells in the presence of tunicamycin or after glucose starvation. K8/18-bound grp78 can be dissociated by Mg-ATP and the association can be reconstituted in vitro using purified grp78, then redissociated again by Mg-ATP. Binding of grp78 occurs preferentially with K8, and when reconstituted does not depend on the posttranslational modification state of K8/18. Co-incubation of K8/18 with hsp70 and grp78 shows preferential association with hsp70. Our results demonstrate a direct association of grp78 with K8 under conditions that induce grp78 expression.

Adenosine Triphosphate↗
PubMed1997

Rapid identification and isolation of zebrafish cDNA clones.

A fast and economical approach, referred to as cDNA clone tagging, was adapted to identify and isolate zebrafish cDNA clones. The basic approach was to partially sequence the coding region of size selected cDNA clones and the partial sequences were then used as tags for identifying the clones through homology search. To benefit maximally from the tagging approach, two cDNA libraries, derived from embryonic and adult fish poly(A)+ RNAs, respectively, were constructed by unidirectional cloning; conceptually, they have the potential to represent all expressed zebrafish genes. A total of 1084 clones were sequenced from the two libraries, and 511 clones were identified, based on sequence homology. These identified clones were derived from at least 261 genes, encoding 48 translational machinery proteins, 47 cytosolic proteins, 43 cytoskeletal proteins, 41 nuclear proteins, 32 membrane proteins, 22 secreted proteins, 20 mitochondrial proteins and 8 proteins with an unknown location. Of the 261 distinct cDNA clones identified, 254 were isolated for the first time in the zebrafish. These tagged cDNA clones, identified and unidentified, provide rich resources for developmental analysis as well as mapping of zebrafish genome. The long-term objective of this study is to establish a tagged zebrafish gene library that can be accessed both by hybridization screening against the plasmid DNAs and by electronic screening using the sequence information.

Animals↗
PubMed1997

Growth hormone regulates ternary complex factors and serum response factor associated with the c-fos serum response element.

For insight into the mechanisms of gene regulation by growth hormone (GH), the regulation of transcription factors associated with the serum response element (SRE) located upstream of c-fos was examined. The SRE can mediate induction of reporter expression in response to GH. For insight into the mechanism by which GH regulates transcription factors, regulation of SRE-associated proteins by GH was examined. In nuclear extracts from 3T3-F442A fibroblasts, several SRE-binding complexes were identified by electrophoretic mobility shift assay. GH treatment for 2-10 min transiently increased binding of two complexes; binding returned to control values within 30 min. The two GH-stimulated complexes were supershifted by antibodies against the serum response factor (SRF), indicating that they contained SRF or an antigenically related protein. One of the GH-stimulated complexes was supershifted by antibody against Elk-1, suggesting that it contains a ternary complex factor (TCF) such as Elk-1 in addition to SRF. Induction of binding by GH was lost when the SRF binding site in the SRE was mutated, and mutation of either the SRF or TCF binding site altered the pattern of protein binding to the SRE. Mutation of the SRF or TCF binding site in SRE-luciferase plasmids inhibited the ability of GH to stimulate reporter expression, supporting a role for both SRF and TCF in GH-induced transcription of c-fos via the SRE. The TCF family member Elk-1 is capable of mediating GH-stimulated transcription, since GH-stimulated reporter expression was mediated by the transcriptional activation domain of Elk-1. Consistent with this stimulation, GH rapidly and transiently stimulated the serine phosphorylation of Elk-1. The increase was evident within 10 min and subsided after 30 min. Taken together, these data indicate that SRF and TCF contribute to GH-promoted transcription of c-fos via the SRE and are consistent with GH-promoted phosphorylation of Elk-1 contributing to GH-promoted transcriptional activation via the SRE.

3T3 Cells↗
PubMed1997

Immunohistochemical studies on Waf1p21, p16, pRb and p53 in human esophageal carcinomas and neighboring epithelia from a high-risk area in northern China.

To better understand the roles of p53 and cell cycle-regulating protein alterations in human esophageal carcinogenesis, we investigated immunohistochemically the distribution patterns of Waf1p21, pRb, p16 and p53 in 22 cases of surgically resected esophageal cancer as well as in the neighboring non-cancerous squamous epithelia. Waf1p21 protein was detected in 13 of the 20 cases of well-differentiated squamous-cell carcinoma (SCC), where the Waf1p21-positive cells were located mainly in the interior layers of the cancer nests. Conversely, p53-positive cells were found mostly in the peripheral layers. Cells containing both Waf1p21- and p53-positive immunostaining were not observed in a double-immunostaining experiment. p16 was detected in both the nucleus and cytoplasm in 3 of the 22 cases of SCC. All of these p16-positive cancers showed an absence of pRb immunostaining; this result is consistent with the idea that expression of p16 is regulated negatively by pRb. Eleven of the 22 esophageal SCCs (50%) showed extensive pRb immunostaining cells, and the remaining 11 cases displayed a few pRb-positive cells or an absence of pRb immunostaining. In a majority of the morphologically normal squamous-cell epithelia samples, immunostaining of Waf1p21 and pRb was found in most of the cells in the parabasal layers (proliferation compartment), where PCNA-positive cells also resided. In the pre-cancerous lesions, Waf1p21 and pRb were detected in cells surrounding the top of the lesioned region, p16-positive cells were scattered in the basal cell hyperplastic and dysplastic lesions and p53-positive cells existed in 2 distinct patterns: "scattered" and "focal".

Carcinoma, Squamous Cell↗
PubMed1997

Stress, apoptosis, and mitosis induce phosphorylation of human keratin 8 at Ser-73 in tissues and cultured cells.

Simple epithelia express keratins 8 (K8) and 18 (K18) as their major intermediate filament proteins. We previously showed that several types of cell stress such as heat and virus infection result in a distinct hyperphosphorylated form of K8 (termed HK8). To better characterize K8/18 phosphorylation, we generated monoclonal antibodies by immunizing mice with hyperphosphorylated keratins that were purified from colonic cultured human HT29 cells pretreated with okadaic acid. One antibody specifically recognized HK8, and the epitope was identified as 71LLpSPL which corresponds to K8 phosphorylation at Ser-73. Generation of HK8 occurs in mitotic HT29 cells, basal crypt mitotic cells in normal mouse intestine, and in regenerating mouse hepatocytes after partial hepatectomy. Prominent levels of HK8 were also generated in HT29 cells that were induced to undergo apoptosis using anisomycin or etoposide. In addition, mouse hepatotoxicity that is induced by chronic feeding with griseofulvin resulted in HK8 formation in the liver. Our results demonstrate that a "reverse immunological" approach, coupled with enhancing in vivo phosphorylation using phosphatase inhibitors, can result in the identification of physiologic phosphorylation states. As such, K8 Ser-73 phosphorylation generates a distinct HK8 species under a variety of in vivo conditions including mitosis, apoptosis, and cell stress. The low steady state levels of HK8 during mitosis, in contrast to stress and apoptosis, suggest that accumulation of HK8 may represent a physiologic stress marker for simple epithelia.

Animals↗
PubMed1997

Characterization of early pulmonary hyperproliferation and tumor progression and their inhibition by black tea in a 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis model with A/J mice.

The pathogenesis of pulmonary tumors induced by a tobacco carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and its inhibition by black tea have been characterized. Female A/J mice (6 weeks old) were treated with a single dose of NNK (103 mg/kg of body weight, i.p.) on day 0, and the cell proliferation index was measured by the incorporation of bromodeoxyuridine (BrdUrd) immunohistochemically. The number of BrdUrd-labeled cells increased in the bronchiolar epithelium from day 2 to day 14, with the highest proliferation rate observed on day 5. By day 35, the BrdUrd-labeling index returned to the level of the control group. Further examination of the day 35 samples revealed the presence of foci of hyperproliferative cells in the bronchiolar epithelium, particularly in the bronchiolalveolar regions. These proliferating bronchiolar epithelial cells (Clara cells) may be the initiated sites for pulmonary tumorigenesis. In this short-term model, administration of black tea polyphenols (0.3%) through the drinking water starting 24 h after NNK treatment significantly inhibited NNK-induced early bronchiolar cell proliferation on day 5. In long-term studies, adenomas were observed in 100% (15 of 15) of the mice at week 16, with 7.8 +/- 0.8 tumors per mouse. At week 52, a malignant tumor incidence of 80% (41 of 51 mice) and a malignant tumor multiplicity of 2.39 +/- 0.19 were observed. The growth patterns of the malignant tumors, which included solid, papillary, and mixed types, may be associated with the cellular origin of the tumor. The cell proliferation indices, as measured by proliferating cell nuclear antigen immunohistochemistry, were significantly higher in dysplasia within adenoma than in adenoma, and significantly higher in adenoma at week 52 than in adenoma at week 16. Administration of black tea, starting 16 weeks after a single dose of NNK, inhibited the progression of adenoma to adenocarcinoma as determined by both malignant tumor incidence and multiplicity. The cell proliferation rate in adenomas was also suppressed by black tea treatment. The present work demonstrates the antiproliferative activities of black tea and its polyphenols. Such activities, at the early and late stages of lung tumorigenesis, may be important for the cancer-chemopreventive activities of black tea.

Animals↗
PubMed1997

Black tea constituents, theaflavins, inhibit 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice.

The present study investigated the inhibitory activity against lung tumorigenesis by a group of characteristic black tea polyphenols, theaflavins. In a short-term study, female A/J mice were treated with a single dose of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK; 103 mg/kg b.w., i.p.) on day 0, and 0.1 and 0.3% theaflavins were administered as the sole source of drinking fluid starting 24 h after NNK treatment. The proliferation index of the lung tissues was measured by the incorporation of bromodeoxyuridine (BrdU) immunohistochemically. The highest NNK-induced proliferation rate of bronchiolar cells, observed on day 5, was significantly decreased by 0.3% theaflavins (proliferation index, 1.51 +/- 0.08 versus 2.35 +/- 0.16). In a long-term lung tumorigenesis study, pulmonary adenomas were observed in 100% (30/30) of the mice at week 16 after NNK treatment. Administration of theaflavins (0.1%) as the sole source of drinking fluid, starting 2 days after the NNK treatment until the termination of the experiment, significantly reduced the tumor multiplicity and volume by 23% (8.5 +/- 0.6 versus 6.5 +/- 0.6 tumors/mouse) and 34% (0.08 versus 0.05 mm3 per tumor), respectively. The proliferation index in lung adenomas was also significantly inhibited by theaflavins. The present work demonstrates the inhibitory action of theaflavins against NNK-induced pulmonary hyperproliferation and tumorigenesis.

Animals↗
PubMed1997

Combining time and intensity effects in assessing operator information-processing load.

A quantitative description of the human information processor is required for predicting operator workload and performance from the simulated task time line data generated by task network models and related methods. Although many models of workload exist, few appear to be well founded in theory or to provide a satisfactory basis for a quantitative representation of operator load. Adherents of both time- and intensity-based models of operator load individually claim success for their methods, which might suggest that both factors are operating in determining operator workload and performance. This paper describes a study that explicitly investigates the relationship between a time-based factor and an intensity-based factor (amount of information to be processed) within a simulated air traffic control environment. A model is developed that posits that the load on the human information-processing system results directly from the ratio of the time necessary to process the required information to the time allowable for making a decision. This ratio, which can be identified with time pressure, determines subjective estimates of workload as well as operator performance. The model is tested against the data from the air traffic control simulation.

Adult↗
PubMed1997

An abundant zebrafish cDNA clone encodes a ras-like protein which is expressed ubiquitously.

An abundant clone from a zebrafish embryonic cDNA library was identified and sequenced. It encodes a ras-like protein, being 94-95% identical to vertebrate Ran, ras-related nuclear protein. The zebrafish Ran mRNA is expressed in all tissues examined and throughout embryogenesis; therefore, it is likely that the Ran protein functions in all types of cells.

Amino Acid Sequence↗
PubMed1997

[Screening new photosensitizers from Chinese medicinal herbs and searching for herbal photodynamic killing effects on human stomach cancer cells].

OBJECTIVE: To find new photosensitizers from Chinese medicinal herbs for cancer photodynamic therapy. METHODS: The extracts of thirteen herbs were examined: (1) Their fluorescence excitation wave lengths and emission wave lengths; (2) Their fluorescence intensity in living cells and (3) Their distribution and localization in the living cells and the fixed cells both stained in each extract, and responses of cell fluorescence intensity to pH value change. Furthermore, the herb's anticancer photosensitive efficiencies were studied by using BCG-823 human stomach cancer cells. RESULTS: Cortex phellodendri and Rhizoma Coptidis, were found with optimal fluorescence properties as photosensitizers in this test. The latter could remarkably reduce the cell metabolic viability, proliferative ability and increased the cell mortality when the cells exposed to both drugs and luminance but not only to drug. CONCLUSIONS: The potential of Chinese medicine as new kind of photosensitizer and its possibility for use in anticancer photodynamic therapy are existed.

Drug Screening Assays, Antitumor↗
PubMed1997

[Endoscopic and CT evaluation of three types of intranasal ethmoidectomies].

To evaluate the curative effects and complications of conventional, microscopic and endoscopic intranasal ethmoidectomuies, 130 cases of sinusitis and polys (stage II) were operated on with intranasal ethmoidectomies. There were 40 conventional, 40 microscopic, and 50 endoscopic ethmoidectomies, followed-up with endoscopy and CT scanning. The results showed that 1. the relieve of symptoms in the endoscopic group(94.0%) was obviously better than the conventional (60.0%) and the microscopic groups (70.0%, P < 0.01): 2. the clinical cure rate in the endoscopic group (86.0%) was obviously higher than the conventional (40.0%) and the microscopic groups (52.5%, P < 0.01); the CT scans showed a normal ratio in the endoscopic group(82.0%) obviously higher than those in the conventional (22.5%) and microscopic groups (37.5%, P < 0.01); 3. the complication ratio in the endoscopic group(12.0%) was slightly higher than those in the conventional(5.0%) and the microscopic groups (2.5%, P > 0.05). The intranasal endoscopic ethmoidectomy was more successful than the conventional and microscopic ethmoidectomies, but attention should be paid to the possibility of complications.

Adult↗
PubMed1997

[The in vitro inhibitory effect of CD8+ cells from patients with aplastic anemia on normal CFU-GM growth was blocked by cimetidine].

OBJECTIVE: To investigate the effect of histamine type II (H2) receptors on the inhibition of hematopoiesis by CD8+ cells from aplastic anemia (AA) patients. METHODS: The effects of CD8+ cells and/or cimetidine, alone or in combination, on normal human CFU-GM growth were studied by using CFU-GM assay. RESULTS: The CD8+ cells from the peripheral blood of AA patients significantly suppressed the growth of normal allogeneic CFU-GM. This inhibitory effect could be blocked by 0.5 x 10(-5) mol/L or 1.0 x 10(-5) mol/L cimetidine. 1.0 x 10(-5) mol/L cimetidine alone slightly inhibited the growth of normal CFU-GM, but 0.5 x 10(-5) mol/L cimetidine did not. CONCLUSION: H2 receptor antagonist cimetidine abolished the suppressive effect of AA patients CDB+ cells on the growth of normal CFU-GM.

Adult↗
PubMed1997

[Analysis of PTH amino acids by micellar electrokinetic capillary chromatography].

A useful method for separation of 19 PTH amino acids by micellar electrokinetic capillary chromatography has been developed. Experiments were performed at 35 degrees C with 14kV power, 50microm x 57cm fused-silica capillary column and UV absorption detector. Each new capillary was washed with 0.1mol/L NaOH and deionized water, each for 15min, before use. Samples were injected into the capillary by applying pressure (3402Pa) for 5s. Absorption detection was at 200nm. The running buffer was made up of 50mmol/L sodium dodecyl sulfate (SDS), 50mmol/L sodium of phosphate and borate (pH 7. 0). The infulence of operation voltage, pH of buffer, temperature and SDS concentration on the amino acids migration has been studied. The coefficients of variaton of migration time and peak area of 19 PTH amino acids were below 1.0% and 5.0% respectively. The detection limits were 0.1-0.25pmol.

Amino Acids↗
PubMed1997

[Capillary isoelectric focusing of protein].

A capillary isoelectric focusing (CIEF) method was developed for the separation of proteins with different pI. Uncoated capillary (57 cm x 50 microm i.d.) was used instead of commercial coated column because of its ease in use and a longer lifetime. Polymeric additive, methylcellulose (MC-1500), acts as dynamic coating of the silica wall to suppress electroendosmosis. TEMED was used to extend the pH range of ampholine. Taurine was added to the ampholyte mixture to eliminate the aggregation of proteins. The uniform design, a new experimental design method suited for experiments of a large number of factors and levels, was used for the optimization of experimental conditions, such as concentrations of ampholine, MC-1500, TEMED and Taurine. U6* (6(4)) table was chosen to arrange experiments. Regression equations of maximum current, mean migration time and criterion of resolution power were obtained after the treatment of experimental results by SAS software. Optimized experimental conditions were obtained according to multivariate regression equations. Carrier ampholyte which consists of 3.2%-4.8% ampholine 3-10, 0.06%-0.18% MC-1500, 0.8% TEMED and 1%-2% taurine will produce good resolution. Cathode and anode solutions were 20 mmol/L NaOH and 20 mmol/L HsPO4, respectively. Low pressure (34.5kPa) was applied at the inlet of the capillary simultaneously after 31 minutes of isoelectric focusing at 25 kV to mobilize the focused acidic protein zone to pass through the detector. Human serum albumin (HSA) and human epidermal growth factor (hEGF) were separated by this method using an ampholyte mixture of 4% ampholine 3-10, 0.8% TEMED, 1% taurine and 0.12% MC-1500. Data analysis indicated that the coefficients of variation of pressure and the method are all 1.2%. The results demonstrated that the method established is applicable to basic, neutral and acidic proteins, and can be used for the determination of pI by internal calibration.

Ampholyte Mixtures↗