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J L Hu

Publications and source records attributed to J L Hu.

At least 19 recordsLinked to original sources
PubMed2001

Polymorphism of flagellin A gene in Helicobacter pylori.

AIM: To study the polymorphism of flagellin A genotype and its significance in Helicobacter pylori (H. pylori). METHODS: As the template, genome DNA was purified from six clinical isolates of H. pylori from outpatients, and the corresponding flagellin A fragments were amplified by polymerase chain reaction. All these products were sequenced. These sequences were compared with each other, and analyzed by software of FASTA program. RESULTS: Specific PCR products were amplified from all of these H. pylori isolates and no length divergence was found among them. Compared with each other, the highest ungapped identity is 99.10%, while the lowest is 94.65%. Using FASTA program, the alignments between query and library sequences derived from different H. pylori strains were higher than 90%. CONCLUSION: The nucleotide sequence of flagellin A in H. pylori is highly conservative with incident divergence. This information may be useful for gene diagnosis and further study on flagellar antigen phenotype.

Base Sequence↗
PubMed2001

Relationship between genotype and phenotype of flagellin C in Salmonella.

AIM: To discover the relationship between the genotype and antigen serotype of flagellin C among Salmonella strains. METHODS: Fragment of Salmonella flagellin C in plasmid pLS408 was cloned, sequenced and compared with the corresponding sequence in other strains. Salmonella strains including two typhi strains, one paratyphoid strain, one enteritidis and one typhimurium strain were isolated from outpatients. Genome DNA was purified respectively from these clinical isolates, then the corresponding flagellin C fragment was amplified by polymerase chain reaction,and the amplification products were analyzed by agarose gel electrophoresis. RESULTS: The cloned fragment includes 582 nucleotides encoding the variable region and partial conservative region of Salmonella flagellin C in plasmid pLS408. With comparison to the corresponding sequences reported previously, there is only a little difference from other strains with the same flagellar serotype in both nucleotide and amino acid level. Specific PCR products were amplified in Salmonella strains with flagellar serotype H-1-d including S. muenchen, typhi and typhimurium, but not in S. paratyphoid C or S. enteritidis strains. CONCLUSION: In this experiment, the specificity of nucleotide sequence could be found in flagellin C central variable regions as it exists in flagellar serotypes in Salmonella. It may be helpful to developing a rapid, sensitive, accurate and PCR-based method to detect Salmonella strains with serotype H-1-d.

Amino Acid Sequence↗
PubMed2001

[ICAM-1 expression of rat brain microvascular endothelial cells caused by fluid shear force].

We studied the effect of shear stress (SS) on intercellular adhesion molecule-1 (ICAM-1) expression of rat brain microvascular endothelial cells (RBMECs) using the parallel plate flow chamber method. It was demonstrated that RBMECs showed a time-dependent, but not a force-dependent, upregulation in ICAM-1 expression. Endothelial cell surface expression of ICAM-1 in the supernatants of RBMECs exposed to SS was not changed, thus excluding the possibility that the upregulated expression is due to the factors synthesized by these cells. These data throw light on understanding the signal transduction pathway inside the endothelial cells under the effect of SS.

Animals↗
PubMed2000

Pertussis toxin treatment prevents 5-HT(5a) receptor-mediated inhibition of cyclic AMP accumulation in rat C6 glioma cells.

We have investigated the functional coupling of the rat 5HT(5a) receptor subtype to adenylate cyclase in a rat C6 glioma cell line. In 5HT(5a) receptor-transfected cells, 5HT caused a concentration-dependent inhibition of forskolin-stimulated cAMP accumulation, with an EC(50) value of 41 nM and a maximal effect of 57% inhibition. This effect was dependent on the concentration of forskolin used to elevate cAMP levels. Methiothepin (1 mcM), which has high affinity for the 5HT(5a) receptor, antagonized the 5HT(5a) receptor-mediated inhibition, and unmasked a stimulation of cAMP formation similar to that observed in untransfected cells, whereas ketanserin (0.1 mcM) enhanced the inhibitory effect of 5HT. Pertussis toxin treatment (0.5 mcg/ml) completely blocked the inhibitory effect of 5HT on cAMP formation, also revealing increase in cAMP accumulation. Pretreatment of the transfected membranes with pertussis toxin abolished subsequent ADP-ribosylation of a 41 kDa protein, correlating the cAMP effect with a functional uncoupling of an inhibitory G protein from its receptor. These results demonstrate an efficient functional coupling of the rat 5HT(5a) receptor to the inhibition of adenylate cyclase via a pertussis toxin-sensitive G[alpha(i)], inhibitory G-protein.

Adenosine Diphosphate Ribose↗
PubMed1999

Antitumor components from an actinomycete strain 6011W.

Three bioactive compounds that inhibited nucleoside transport were isolated from the cultured broth of Streptoverticillium sp. 6011W. The structures of those compounds were characterized as cinnamamide, N-(tetrahydro-2-oxo-3-thienyl)-acetamide and benzamide, respectively. They all inhibited radiolabeled thymidine transport into Ehrlich carcinoma cells, with IC50 values of 30.4, 97.2 and 85.4 microM, respectively. When administered i.p., cinnamamide not only inhibited the growth of transplanted tumors but also reduced the number of lung metastases in mice bearing Lewis lung carcinoma. The results suggest that nucleoside transport inhibition assay is a valuable model to search for antitumor agents of natural origin.

Actinomycetales↗
PubMed1997

[Ceramide pathway].

Ceramide may be generated from many metabolism routes. As a novel second messenger, ceramide plays important roles in a variety of physiologic or pathologic events relating to cellular growth, proliferation, differentiation, apoptosis and injuries. It is expected that new insights into the ceramide pathway would promote our understanding of the complex mechanisms for signal transduction.

Animals↗
PubMed1996

Enhancement of glucocorticoid receptor-mediated gene expression by cellular stress: evidence for the involvement of a heat shock-initiated factor or process during recovery from stress.

Recent reports have demonstrated the ability of cellular stress to cause a large increase in the maximal levels of steroid receptor-mediated gene expression, a process we refer to as the heat shock potentiation effect (HSPE). In the present work, we have analyzed the time of appearance of the HSPE on the glucocorticoid receptor (GR) of L929 cells stably-transfected with the MMTV-CAT reporter plasmid (LMCAT2 cells). In LMCAT2 cells exposed to heat shock (43 degrees C, 2-h) before addition of 1 microM dexamethasone, the first appearance of HSPE (CAT levels greater than hormone-alone) occurred at 8 h of recovery and continued to increase by 24 h of recovery. Treatment of LMCAT2 cells with 1 microM dexamethasone for 2 h before heat or chemical shock (sodium arsenite) resulted in the same delayed onset pattern for the HSPE. Based on a [35S]methionine assay and tests of L929 cells stably transfected with the constitutive pSV2-CAT reporter, evidence is provided that the delayed appearance of the HSPE is not due to the heat shock block of general protein synthesis or to specific repression of CAT mRNA expression or translation. By using short-term incubations (4 h) with dexamethasone during the recovery period, the peaks of HSPE expression during recovery were determined to be 12-16 h for CAT enzyme activities, and 4-8 h for CAT mRNA expression. Taken together, these results provide evidence that the timing of the HSPE is not dependent on the rate of GR activation, or on the type of stress, but rather on a factor or process that is either synthesized or activated during the recovery period following stress.

Animals↗
PubMed1995

Antibiotic C3368-A, a fungus-derived nucleoside transport inhibitor, potentiates the activity of antitumor drugs.

Antibiotic C3368-A (CA) is produced by a fungus strain from a soil sample collected in Antarctica. CA markedly inhibited radiolabeled thymidine and uridine transport in mouse Ehrlich carcinoma cells, its 50% inhibitory concentration (IC50) being 4.6 and 7.7 microM, respectively. In clonogenic assay, CA displayed a synergistic effect with methotrexate (MTX), mitomycin C (MMC), 5-fluorouracil (5FU), and Adriamycin (ADR) against human oral epidermoid carcinoma KB cells. CA also markedly enhanced the inhibitory effect of 5FU and ADR on the proliferation of human hepatoma BEL-7402 cells as determined by the p-nitrophenyl-N-acetyl-beta-D-glucosaminide (NAG) enzyme-reaction assay. 5FU or ADR cytotoxicity was not augmented by CA in human fetal lung 2BS cells. In vivo, CA significantly potentiated the inhibitory effect of MMC against colon carcinoma 26 in mice. No significant augmentation of toxicity by the combination was found in treated mice. The results suggest that CA, the newly found nucleoside-transport inhibitor, may be useful in potentiation of the effect of antitumor drugs.

Animals↗
PubMed1994

Potentiation of glucocorticoid receptor-mediated gene expression by heat and chemical shock.

We have examined the effects of heat shock on glucocorticoid receptor (GR)-mediated gene transcription in an L929 cell line derivative (LMCAT2) stably transfected with the mouse mammary tumor virus-chloramphenicol acetyltransferase (MMTV-CAT) reporter plasmid. Exposure of the LMCAT2 cells to heat or chemical shock resulted in a large increase in dexamethasone (Dex)-induced expression of CAT enzyme activity. This potentiation of hormone-induced MMTV-CAT expression was dependent on the magnitude of the stress event and on the Dex concentration, with maximal increases observed for 1 microM Dex after 2 h at 43 C or 2 h at 200 microM sodium arsenite. Heat shock potentiation of MMTV-CAT expression was not seen in an L929 cell derivative devoid of GR or in LMCAT2 cells treated with RU486 antagonist, suggesting that this effect of stress on CAT gene expression was mediated by the GR. Using a quantitative Western blot procedure, the amount of GR protein in the nucleus of cells subjected to combined heat shock and Dex treatment was no greater than the amount of nuclear GR in cells treated with hormone alone, indicating that the stress potentiation effect was not the result of increased nuclear translocation or retention by the GR. In addition, equally strong potentiations of MMTV-CAT expression were observed for cells subjected to heat shock either before or after Dex-mediated translocation of the GR to the nucleus. Thus, the major effect of stress on GR transcription enhancement activity appears to occur after the GR is bound to its high affinity nuclear acceptor sites. We have used a series of MMTV-CAT reporter constructs containing varying portions of the long terminal repeat regulatory region to show that a putative heat shock transcription factor-binding sequence at position -437 of the long terminal repeat is not required for this effect of heat shock on MMTV-CAT expression. A stress-induced increase in hormone-mediated CAT gene expression was observed for a minimal CAT reporter controlled by two synthetic glucocorticoid response elements and a TATA box sequence. Thus, it is unlikely that any DNA-binding transcription factor, other than GR, is required for this effect of stress on transcription by the hormone-bound GR. Based on these results, a model of heat shock enhancement of GR-mediated gene expression is developed in which stress acts on the DNA-bound GR, on a putative heat shock-activated adaptor, or on components of the RNA-polymerase-II complex.

Animals↗
PubMed1994

[Labeling of granulocytic granules with RNase-gold probes].

By using ribonuclease-gold (RNase-G) probes, ultrastructural localization of ribonucleic acid (RNA) was performed in inflammatory cells from gastric mucosa biopsies of gastric cancer and gastritis, and in peripheral leukocytes from normal subjects as well as from granulocytic leukemia patients. Electron microscopically, the azurophilic granules of monocytes and lymphocytes in gastric mucosa were not labeled by RNase-G, while various cytoplasmic granules of neutrophils, eosinophils and basophils were all positively labeled. Labeling of the peripheral leukocytes from normal subjects was the same as above. It is important to find in the present study that the cytoplasmic granules of the peripheral leukemic cells from granulocytic leukemia patients were not labeled by RNase-G. The significance of the afore-mentioned findings lies on one hand in the fact that it could make a revision of the conventional views of the granular composition. On the other hand, the data indicate that the RNase-G technique is potentially explorable for future clinical utilization.

Adenocarcinoma↗
PubMed1994

Detection of antigen-specific immune complexes in sera of gastric and esophageal cancer patients.

Using the murine monoclonal antibodies against human gastric cancer cell antigens designated MG7 and MGd1, we developed a sandwich ELISA to detect the levels of antigen-specific immune complexes (IC) in human sera. By this assay, only 6.7%(6/90) of healthy blood donors and 9.2%(6/65) of patients with chronic gastritis had antigen-specific IC in sera exceeding the cut-off value. Whereas 21.4%(6/28) of patients with colorectal cancer, 18.2%(4/22) of patients with hepatocellular cancer, 11.4%(4/35) of patients with lung cancer and 9.5%(2/21) of patients with breast cancer had elevated levels of the antigen-specific IC. In contrast, 58.7%(54/92) of patients with gastric cancer and 53.3%(24/45) of patients with esophageal cancer were positive for this antigen-specific IC. Determination of levels of antigen-specific IC in sera may be useful in serologic diagnosis of patients with gastric and esophageal cancer.

Animals↗
PubMed1994

[The expression of mutant p53 gene in gastric carcinoma].

Loss or inactivation of p53 gene--a suppressor oncogene has been considered to be one of the important mechanisms in the development of human tumors. One of the evidences for mutation of allelic gene of p53 is the identification of p53 protein concentrated in the nuclei of related cells. By using ABC immunohistochemical method, we studied the expression of p53 in cryostatic sections of the tumor tissue and adjacent mucosa resected from 38 patients with gastric cancer. p53 was found to be positive in the nuclei with intensive staining in 24 out of 38 cases with carcinoma (63.2%). p53 positive cells were distributed diffusively in the cancer tissue. All the adjacent mucosa specimens except 10 were negatively stained with p53 monoclonal antibody. These 10 specimens including 3 with dysplasia and 4 with metaplasia were only weakly stained. p53 was also found to be positive in 18 out of 23 cancer patients with metastasis in perigastric lymph nodes (78.3%). We also studied in the same section the nucleolar organizer region-associated proteins (AgNORs) with using silver staining technique to find if there is any relationship between p53 gene mutation and the activity of rRNA transcription of tumor cells. The number of AgNORs dots per nucleus detected in gastric cancer sections with positive staining of p53 (9.9 + 2.14) was greater than those with p53 negative staining (7.2 + 1.68). There was a significant statistical difference between the two groups (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1991

Diagnostic significance of gastric cancer associated antigens (MG-AGS) in serum, ascitic fluid and gastric juice.

A group of monoclonal antibodies against gastric cancer, pooled in equal proportions, was used to investigate their corresponding antigens (MG-Ags) in serum and body fluid of patients with gastrointestinal cancer and benign diseases using microsphere-ELISA method. The mean serum level (plus 3 standard deviations) in 59 normal subjects was arbitrarily set as the positive threshold value. The positive rate was found to be 68.8% (135/196) in sera of patients with gastric cancer, 70% (14/20) in colonic cancer, 72.2% (24/33) in rectal cancer, 43.8% (7/16) in esophageal cancer, 45.5% (5/11) in cholecystic cancer and 34.9% (15/43) in lung cancer, which, however, was not found in primary liver cancer, pancreatic cancer and ovarian cancer. In 214 patients with benign diseases, a false positive rate was 7.48%. In gastric juice and ascitic fluid of patients with gastric cancer, the positive rates were found to be 61.7% (27/44) and 83.3% (20/24) respectively. These antigens were also determined repeatedly in sera of patients with gastric cancer who had undergone gastrectomy. It was found that the level of MG-Ags in sera began to decrease at 8-10 days after operation. These results suggest that the determination of MG-Ags is useful in the diagnosis of gastrointestinal cancer and evaluation of the treatments.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1990

Studies on gastrin in duodenal ulcer.

By immunocytochemical method and radioimmunoassay, the gastrin secreting cells (G cells) and gastrin concentration in antral mucosa, gastric juice and serum in 20 patients with duodenal ulcer (DU) were studied. The number of G cells and gastrin concentration in antral mucosa showed no significant difference as compared with normal control. The number of G cells in patients with DU and antral atrophy was much higher than those with antral atrophy but with DU. It indicated that G cells were increased in number in DU, and the gastrin concentration in gastric juice (271.11 +/- 255.25 pg/ml) was much higher than in sera (74.71 +/- 43.07 pg/ml). G cells were distributed in different parts of pyloric glands, showing that gastrin in gastric juice should come directly from G cells. The disturbance of feedback mechanism in regulating gastric acidity might be an important role in hypersecretion of gastric acid in DU. The increase of gastrin concentration in gastric juice might be closely related to hyperplasia of parietal cells.

Adult↗