A general method to identify bacterial genes regulated by cell-to-cell signaling.
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Artificial Gene Fusion↗
Biomedical subjects
X Ding
Publications and source records attributed to X Ding.
Hypotensive and physiological effect of angiotensin converting enzyme inhibitory peptides derived from soy protein on spontaneously hypertensive rats.
Angiotensin converting enzyme (ACE) inhibitory peptides prepared from soy protein by the action of alcalase enzyme was tested for its hypotensive effect on spontaneously hypertensive rats (SHR). Captopril, an ACE inhibitor used widely for hypertension treatment, was also applied in comparison. A significant (p < 0.05) decrease in systolic blood pressure of SHR was observed when soy ACE inhibitory peptides were orally administrated at three different dose levels (100, 500, and 1000 mg/kg of body weight/day), whereas little change occurred in the blood pressure of normotensive rats even at the highest dose. After a month-long feeding, blood pressure readings of SHR fell by approximately 38 mmHg from the original level at the lowest dose; a steadily and progressively hypotensive effect existed for these soy ACE inhibitory peptides administration groups. An obvious fluctuation was observed at the third week, although Captopril had a stronger hypotensive effect. The ACE activity of serum, aorta and lung, and lipid content of serum of SHR upon administration of soy ACE inhibitory peptides did not show a significant difference from that of the control group, whereas the serum ACE activity increased and the aorta ACE activity decreased significantly (p < 0.05) for the Captopril group. Serum Na(+) concentration decreased significantly in both the peptides-treated groups and the Captopril-treated group in comparison with the control group, whereas no lowering effect was observed for serum K(+) and serum Ca(2+) concentrations. These results suggested that the hypotensive effect of ACE inhibitory peptides derived from soy protein could be at least partly attributed to the action on salt/water balance.
Angiotensin-Converting Enzyme Inhibitors↗
Mutations in the gene encoding lecithin retinol acyltransferase are associated with early-onset severe retinal dystrophy.
The chromophore of the visual pigments, 11-cis retinal, is derived from vitamin A (all-trans retinol) through a series of reactions that take place in retinal pigment epithelium (RPE); (ref. 1). The first of these reactions is catalyzed by lecithin retinol acyltransferase (LRAT); (ref. 2). We screened 267 retinal dystrophy patients for mutations in LRAT and identified disease-associated mutations (S175R and 396delAA) in three individuals with severe, early-onset disease. We showed that the S175R mutant has no acyltransferase activity in transfected COS-7 cells. Our findings highlight the importance of genetic defects in vitamin A metabolism as causes of retinal dystrophies and extend prospects for retinoid replacement therapy in this group of diseases.
Acyltransferases↗
Signal peptide-selection of cDNA cloned directly from the esophageal gland cells of the soybean cyst nematode Heterodera glycines.
Secretions from the esophageal gland cells of plant-parasitic nematodes play critical roles in the nematode-parasitic cycle. A novel method to isolate cDNA encoding putative nematode secretory proteins was developed that utilizes mRNA for reverse transcription-polymerase chain reaction derived from microaspiration of the esophageal gland cell contents of parasitic stages of the soybean cyst nematode Heterodera glycines. The resulting H. glycines gland cell cDNA was cloned into the pRK18 vector, and plasmid DNA was transformed into a mutated yeast host for specific selection of cDNA inserts that encode proteins with functional signal peptides. Of the 223 cDNA clones recovered from selection in yeast, 97% of the clones encoded a predicted signal peptide. Fourteen unique cDNA clones hybridized to genomic DNA of H. glycines on Southern blots and, among them, nine cDNA clones encoded putative extracellular proteins, as predicted by PSORT II computer analysis. Four cDNA clones hybridized to transcripts within the dorsal esophageal gland cell of parasitic stages of H. glycines, and in situ hybridization within H. glycines was not detected for eight cDNA clones. The protocol provides a direct means to isolate potential plant-parasitic nematode esophageal gland secretory protein genes.
Animals↗
Transdifferentiation of human islet cells in a long-term culture.
It has been established that ductal cells or precursor cells within the ductal tree of the pancreas can differentiate into islet cells. Although islet cells can also form exocrine cells, it is unclear whether they arise from precursor (stem) cells or from mature endocrine cells by transdifferentiation. Using a defined culture medium and technique for islet purification, for the first time we were able to maintain human islets in culture for more than a year. Multilabeling immunohistochemical and immunoelectron microscopic examination of the islets at different days of culture using islet cell markers (antibodies to hormones, neuron-specific enolase, chromogranin A) and ductal cell markers (cytokeratins 7 and 19, carbonic anhydrase II, DU-PAN2, CA 19-9, and MUC1) revealed that endocrine cells gradually transdifferentiate to ductal, acinar, and intermediary cells. Although islet hormone secretion ceased after day 28 in culture, endocrine cells were still detectable at day 60. However, later, all endocrine and exocrine cells were replaced by undifferentiated cells that expressed neuron-specific enolase, chromogranin A, laminin, vimentin, cytokeratin 7 and 19, alpha-1-antitrypsin, transforming growth factor-alpha, and epidermal growth factor receptor. Our data thus show that, under proper conditions, human islets can be maintained in vitro over a long period and that, in the culture condition, islet cells seem to transdifferentiate to exocrine cells and undifferentiated cells, which may be considered pancreatic precursor (stem) cells.
Biomarkers↗
Indole can act as an extracellular signal in Escherichia coli.
Previous work has shown that lacZ fusions to the cysK, astD, tnaB, and gabT genes in Escherichia coli are activated by self-produced extracellular signals. Using a combination of ethyl acetate extraction, reversed-phase C(18) chromatography, and thin-layer chromatography, we have purified an extracellular activating signal from E. coli supernatants. Mass spectrometry revealed a molecule with an m/z peak of 117, consistent with indole. Nuclear magnetic resonance analysis of the purified E. coli factor and synthetic indole revealed identical profiles. Using synthetic indole, a dose-dependent activation was observed with lacZ fusions to the gabT, astD, and tnaB genes. However, cysK::lacZ and several control fusions were not significantly activated by indole. Conditioned medium prepared from a tnaA (tryptophanase) mutant, deficient in indole production, supported 26 to 41% lower activation of the gabT and astD fusions. The residual level of activation may be due to a second activating signal. Activation of the tnaB::lacZ fusion was reduced by greater than 70% in conditioned medium from a tnaA mutant.
Amino Acid Transport Systems↗
Hepatitis B virus genotype distribution among chronic hepatitis B virus carriers in Shanghai, China.
OBJECTIVE: Hepatitis B virus (HBV) genotype distribution is still unclear in China, where a high prevalence of HBV infection exists, although it is well known that HBV can be classified into six genotypes based on intergroup divergence. The aim of this study was to investigate the epidemiological distribution of HBV genotypes and to clarify further the genotype-related differences in the pathogenicity of HBV. METHODS: Seminested PCR and restriction fragment length polymorphism analysis were conducted in 97 asymptomatic HBV carriers (ASC) and 46 chronic hepatitis (CH), 37 liver cirrhosis (LC) and 44 hepatocellular carcinoma (HCC) patients in Shanghai, China. RESULTS: Two hundred and twenty samples (98.2%) were positive for HBV DNA, and of these, 3 (1.4%), 38 (17.2%) and 179 (81.4%) were classified as genotype A, B and C, respectively. There was a statistically significant difference in the distribution of genotypes B and C among various categories of liver diseases (p < 0.01). The distribution of genotype C showed an increasing trend from ASC, CH and LC to the HCC group; in contrast, the distribution of genotype B showed a decreasing trend in the same order. HBeAg positivity was higher in genotype C than in genotype B in all the subjects or in the ASC group alone (p < 0.05, p < 0.01, respectively). More severe liver damage and a higher mean age were observed in genotype C than in genotype B (p < 0.01, p < 0.05, respectively). CONCLUSIONS: These results indicate the following: (1) genotypes A, B and C of HBV exist in Shanghai, China; (2) genotype C is the major genotype in this area; (3) genotype C is associated with the development of severe liver diseases, and (4) genotype B has a relatively good prognosis.
Adolescent↗
Rapid amplification of a water channel-like gene and its flanking sequences from the Methanothermobacter marburgensis genome using a single primer PCR strategy.
In this study, we isolated a water channel-like gene and its flanking sequences from an archaeal genome using only a set of PCR. This method should greatly simplify gene cloning procedures and improve the efficiency of cloning.
Journal Article↗
Electrochemical characteristics of thin nickel hexacyanoferrate films formed on gold and thiol self-assembled monolayers modified gold electrodes.
Nickel hexacyanoferrate (NiHCF) film was prepared and characterized on gold and thiol self-assembled monolayers (SAMs)-modified gold electrodes. It was found that the film exhibited some different electrochemical characteristics compared with that found on a carbon electrode. In the presence of K+, the film exhibited a redox peak at about 0.5 V. The peak potential shifted linearly with the K+ concentration over the range of about 0.1 mM - 0.1 M with slopes of 54 - 60 mV per log[K+]. However, in solutions containing Na+, Li+ or NH4+ ion the film did not generate well-defined peaks, or even a visible redox peak. Therefore, the film showed a selective potential response to K+. The voltammetric behavior of NiHCF film varied with thiols, the preparation procedure and the solution pH. Under certain conditions, the characteristics of the film could be improved to some extent.
Journal Article↗
Identification of a new human CYP2A gene fragment with close linkage to CYP2GP1.
Human genomic libraries were screened to identify CYP2G-related cytochrome P450 genes. A genomic fragment comprising exons 7 through 9 of CYP2GP1 and exons 6 through 9 of a previously unidentified CYP2A gene, designated CYP2A7P2, was isolated from an EMBL3 library; the two genes were arranged in outward opposite directions with about 8 kbp of intervening sequence. The same structure was also detected in a bacteriophage P1 clone, which contained a full-length CYP2GP1 gene, exons 6 through 9 of CYP2A7P2, and the CYP2B7 gene. However, additional CYP2A-related exons as well as other CYP2A genes, CYP2A7P1, CYP2B6, CYP2F1, and CYP2GP2 were not detected. These results indicate that CYP2A7P2 is located near CYP2B7 in the middle of the CYP2A-2B-2F gene cluster on chromosome 19. Furthermore, an analysis of CYP2A sequence alignment suggests that CYP2A7P2 may be derived from the same ancestral gene that gave rise to CYP2A7P1, which was corrupted by a large insertion at intron 5.
Adult↗
Molecular regulation of genes encoding xenobiotic-metabolizing enzymes: mechanisms involving endogenous factors.
It is widely recognized that xenobiotic-metabolizing enzymes play a fundamental role in the basic processes of carcinogenesis and toxicity on one hand, and chemoprevention and drug efficacy on the other. Realization that different factors can profoundly affect the expression of these enzymes at the genome level has resulted in an enhanced appreciation of the importance these genes play in our modern industrialized age. There continues to be rapid proliferation of studies addressing the molecular regulation of these genes. The discovery of common signal transduction pathways and transcription factors that dictate tissue and developmental-specific expression, as well as variation in expression within a given tissue, suggest that there may be significant interaction among these various regulatory systems. This report is a summary of a symposium that was part of the Structure, Function and Regulation of Cytochromes P450 and Xenobiotic Metabolizing Enzymes satellite meeting of the 2000 joint meeting of the American Society for Biochemistry and Molecular Biology, the American Society for Pharmacology and Experimental Therapeutics, the French Pharmacological Society, and the Pharmacological Society of Canada held in Boston, Massachusetts. This symposium brought together several speakers who addressed specific receptor-mediated signal transduction pathways involved in the regulation of xenobiotic-metabolizing enzymes, as well as other molecular mechanisms whereby endogenous factors are involved in controlling tissue- and developmental-specific expression.
Enzymes↗
CYP1B1 expression in human lung.
Cytochrome P450 1B1 is a recently recognized phase I bioactivating enzyme with high affinity for both inhaled tobacco carcinogens and 17beta-estradiol. We evaluated the human lung expression of this multifunctional member of the P450 superfamily across 16 individuals. Expression of CYP1B1 was evaluated by qualitative reverse transcription-polymerase chain reaction and Western immunoblots performed on human tumor and nontumor lung tissue. Expression at both mRNA and protein levels was then correlated with smoking history, plasma biomarkers of tobacco exposure (nicotine and cotinine), gender, and tumor histology. CYP1B1 mRNA and protein were detected in 94 and 100% of individuals, respectively. Multivariate analysis confirmed that there were more subjects displaying CYP1B1 mRNA expression in tumor than nontumor tissue (p = 0.0003). Correlation of CYP1B1 protein with plasma cotinine levels was statistically marginal (p = 0.027). Self-reported smoking history, gender, and tumor histology did not correlate with gene expression in the multivariate model. After multivariate modeling for confounding factors, the expression patterns of 5 of 16 individuals appeared to differ from the group as a whole for mRNA and/or protein. We conclude that CYP1B1 is commonly expressed in human lung and hypothesize that it may be an important phase I enzyme with respect to human lung carcinogen metabolism, warranting an understanding of regulatory control and coding region polymorphisms.
Aryl Hydrocarbon Hydroxylases↗
Treatment of 104 cases of chemotherapy-induced leukopenia by injection of drugs into Zusanli.
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Acupuncture Points↗
Depentylation of the rat esophageal carcinogen, methyl-n-pentylnitrosamine, by microsomes from various human and rat tissues and by cytochrome P450 2A3.
Methyl-n-pentylnitrosamine (MPN) is carcinogenic for the rat esophagus. To determine organ specificity for MPN activation by human tissues, microsomes isolated from human organs (snap-frozen <6 h after death or removed surgically) were incubated with [pentyl-(3)H]MPN, and [(3)H]pentaldehyde formation was measured by high-pressure liquid chromatography of its 2,4-dinitrophenylhydrazone using radioflow assay. With 100 microM MPN, mean depentylation rates were 6.6 (liver), 2.9 to 3.8 (kidney, stomach, small intestine, and colon), and 0.4 to 1.6 (esophagus, lung, and skin) pmol of pentaldehyde/mg of protein/min. Of 14 human esophagi, four showed relatively high depentylation rates of 3.3 to 4.1 pmol/mg/min. Apparent K(m) was 80 to 160 microM (V(max), 3-15 pmol/mg/min) for three esophagi, 90 to 130 (2 livers), and 1330 (1 kidney) microM. Rat tissues showed mean depentylation rates for 100 microM MPN of 24.9 (liver), 14.5 (esophagus), 7.0 (lung), and 0.0 to 2.7 (5 other tissues) pmol/mg/min. MPN depentylation by rat cytochrome P450 2A3 showed an apparent K(m) of 8 microM (V(max), 70 pmol/nmol of P450/min) and was competitively inhibited by the CYP2A inhibitor coumarin (apparent K(i), 4 microM). Coumarin (0.4 mM) inhibited microsomal depentylation of 100 microM MPN by 37 to 62% for human esophagus, liver, kidney, and colon and for rat esophagus but not for rat liver and lung. MPN depentylation by rat esophageal microsomes increased up to 90% on adding P450 reductase. The results indicate organ-specific MPN metabolism by rat but not human esophagus. Nevertheless, the relatively high activity of four human esophagi might indicate increased susceptibility of some individuals to carcinogenesis by unsymmetrical dialkylnitrosamines.
Adult↗
[Production of transgenic lamb integrated with modified human anti-trypsin gene].
This experiment is to produce the human mAAT(modified anti-trypsin) which cures the emphysema specifically through mammalian galactophore of transgenic goat. 56 goats were selected as donor for superovulation by FSF + LH microinjection in this experiment. The pronucleic embryos were injected with human mAAT gene after fertilization in vivo, and transferred to the donors or receptors directly. The superovulation was better in March and May than in December with the number of ovulation of 19.50, 21.70 and 16.06, and number of fertilized embryos of 4.31, 6.48 and 3.57 per-animal respectively. The pregnant rates were 18.18% and 25% respectively after transferred to donors and receptors with natural estrus. The donors also can be used as the embryo receptor with no remarkable decrease of pregnant rate. 29 lamb were labored. 4 positive transgenic lamb were checked by PCR, PCR-Southern and Southern analysis. The integrated efficiency of foreign DNA was 13.79% with microinjection of high copy number of foreign DNA fragment.
Animals↗
[Evaluation of p53, p21waf1, and PCNA in the diagnosis on lung cancer].
OBJECTIVE: To evaluate the diagnostic value of p53, p21waf1 and PCNA on diagnosis of lung cancer. METHODS: One hundred and fourteen lung cancer patients and 89 cases with benign pulmonary diseases were studied on the expression of p53, p21waf1 and PCNA by immunohistochemical staining. The differences of p53, p21waf1 and PCNA expression status between these two groups were compared and the diagnostic value of these three markers was evaluated. RESULTS: (1) The positive rates of p53, p21waf1 and PCNA expression in lung cancer were 47.37%, 75.44% and 80.70%, all significantly higher than that in benign pulmonary diseases (P < 0.001), with odds ratio 39.15, 5.75, 6.76 respectively. (2) The positive likelihood ratio of p53 was 21.08, higher than that of p21waf1 and PCNA. Specificity and Youden index were also higher than those of p21waf1 and PCNA, but the sensitivity of p53 was low. (3) The sensitivity and specificity of p53 and PCNA parallel test were 89.47% and 60.67% respectively. CONCLUSIONS: (1) The expression of p53, p21waf1 and PCNA in lung cancer cases were all upregulated. These three markers all seemed to have strong links with lung cancer. (2) p53 was shown a good marker for lung cancer diagnosis. (3) The diagnostic value of p53 and PCNA parallel test was rather high.
Biomarkers, Tumor↗
Experiment study of effect of perfluorohexyloctane on corneal endothelial cells.
PURPOSE: To investigate the effect of Perfluorohexyloctane (F6H8) on corneal endothelial cells(CEC) of rabbit eyes. METHODS: Fifteen New Zealand white rabbits were divided into two groups: experimental group(F6H8) and control group(BSS). All rabbits underwent anterior chamber injection of 0.15 ml F6H8 or BSS. Slit-lamp biomicroscopy and corneal endothelium photography were performed pre-operatively and postoperatively. Histopathological examination and Transmission electron microscopy(TEM) were done after the rabbits were sacrificed. RESULTS: All the corneas were clear. Since 4 weeks after operation, the endothelial cells were markedly irregular in size and shape and the number of endothelial cells was markedly decreased. Multilayered retrocorneal membranes(RCM) grew gradually 2 weeks after surgery. Vacuolar degeneration was seen in some endothelial cells. Nuclear degeneration and edema of plasma were seen in TEM. CONCLUSION: Corneal endothelial cell degenerated after contacting with F6H8 for 2-4 weeks. As a silicone solvent, it should be removed completely after injection. We don't recommend it to be used as a new intraocular temponade.
Animals↗
[Surgery treatment of retinal detachment with Marfan syndrome].
PURPOSE: To detect the reattachment rate and visual function outcome of Pars Plana Lensectomy, vitrectomy and scleral encircling (PPL + PPV + SE) to treat retinal detachment (RD) with Marfan syndrome. METHODS: A retrospective study of 11 cases of 14 eyes with Marfan syndrome who submitted to PPL + PPV + SE. RESULTS: All the cases were followed up for four - 46 months (means 31.2 months). Retinal reattachment rate was 85.7%, visual acuity were 0.3 or better in eight cases. CONCLUSION: PPL + PPV + SE is a safe and effective treatment for retinal detachment with Marfan syndrome.
Adolescent↗