Biomedical subjects

Yan Fu

Publications and source records attributed to Yan Fu.

44 records · Page 3Linked to original sources

PubMed2003

Mutation and expression of the p53 gene during chemical hepatocarcinogenesis in F344 rats.

Inactivation of the p53 gene is one of the most frequent genetic alterations in carcinogenesis. We studied gene mutations, the mRNA expression of p53, and the accumulation of p53 protein in chemical hepatocarcinogenesis in rats. Samples consisting of 44 precancerous foci and 18 cancerous foci were collected by laser capture microdissection (LCM), and analyzed for mutations in rat p53 gene exons 5-8 by PCR-single-strand conformational polymorphism (PCR-SSCP). We found that 25 PCR-SSCP bands of exons 6/7 and 8 were altered in 22/62 (35.4%) LCM samples. Direct p53 gene sequencing showed that 20/62 (9 precancer, 11 cancer) (32.3%) LCM samples exhibited 34 point mutations. Ten LCM samples exhibited double or triple mutations in exons 6/7 and 8 simultaneously. A quantitative analysis of p53 mRNA showed that p53 mRNA peaked at an early stage (week 6) in the precancerous lesion, 20 times that of adjacent normal tissue, and returned to normal by week 23. Similar to precancer, p53 mRNA in cancer was five times as high as that of adjacent normal tissue at week 12, and was closer to normal at week 23. When p53 mRNA declined from a high to low, positive immunostaining for the p53 protein began to be seen in precancerous and cancerous foci, suggesting that the p53 protein had accumulated in these foci. Results show that p53 gene mutation is present in initial chemical hepatocarcinogenesis and p53 mRNA concentration is clearly elevated before gene mutation. Once the p53 gene has mutated, mRNA concentration progressively declines, suggesting that mutation leads to inactivation of the p53 gene.

Animals↗

PubMed2003

Forkhead transcription factor Foxf2 (LUN)-deficient mice exhibit abnormal development of secondary palate.

The forkhead genes encode a transcription factor involved in embryogenesis and pattern formation in multicellular organisms. They are mammalian transcriptional regulators that bind DNA as a monomer through their forkhead domain. The Foxf2 (LUN) mRNA is expressed in the mesenchyme directly adjacent to the ectoderm-derived epithelium in the developing tongue and in the mesenchyme adjacent to the endoderm-derived epithelium in the gastrointestinal (GI) tract, lungs, and genitalia. To investigate the developmental role of the Foxf2 gene during embryogenesis, we disrupted the Foxf2 gene and showed that these mutant mice died shortly after birth. Mice lacking the Foxf2 gene were found to develop cleft palate and an abnormal tongue. In addition, we found that the GI tract and the lungs of Foxf2-deficient newborn mice were normal in both morphology and function. These results suggest that the Foxf2 gene plays key roles in palatogenesis by reshaping the growing tongue.

Animals↗

PubMed2003

Medium effects on fluorescence of ciprofloxacin hydrochloride.

The medium (pH, organic solvents, cyclodextrin (CD) or surfactants) effects on the fluorescence of ciprofloxacin hydrochloride (CPFX.HCl) were studied in detail. It is found that the three acid constants of ciprofloxacin (CPFX) are near to each other. Therefore the relation curve between pH and fluorescence intensity has no strident change and keeps relative stable in the pH range of 2-7. When pH was in the range of 5.5-6.0, the fluorescence intensity of CPFX reached the max. The kind and amount of organic solvent added to the luminescent system have various effects. Ethanol quenched fluorescence and the fluorescence excitation wavelength is red shift at first and then blue shift. Acetone has complicated effects on the fluorescence properties of CPFX.HCl solution. The experiment result shows that acetone is really a quencher when its volume content in the system is from 0 to 20%, but when its content is 90%, the signal intensity is unexpectedly one and a half times as much as that of no acetone. This means that there is a strong interaction between the acetone and CPFX; CPFX.H(+) could be included into the gamma-CD but the capping effect is not notable. The effect of cationic surfactant cetyltrimethylammonium bromide and non-ionic surfactant TX-100 and TX-80 on CPFX fluorescence was unimpressive, but the anionic surfactant's effect is aberrant. The fluorescence intensity of CPFX.HCl solution experiences three stages of increasing, decreasing and increasing in turn, as sodium dodecyl sulfate is adding gradually. But for sodium lauryl sulfonate, there are only two stages of decreasing and increasing with the concentration increasing. It is problematic to illustrate clearly the effect mechanism of acetone and anionic surfactant at present. Undoubtedly, the experimental results in this paper should be useful in practice works and the research is worth studying still further.

Ciprofloxacin↗

PubMed2003

[Quantitative analysis of p53 and related genes mRNA in rat hepatocarcinogenesis induced by 3'-Me-DAB].

BACKGROUND & OBJECTIVE: p53 gene mutations and abnormal expression of p53 in hepatocarcinoma have been reported, but alteration in mRNA level is not yet understood. In order to find out the alteration in mRNA levels of p53, glutathione S-transferase P (GST-P), alpha-fetoprotein (AFP), and albumin in genesis, developing, and prognosis of hepatocarcinoma, quantitative analysis of mRNA levels of p53, GST-P, AFP, and albumin in prehepatocarcinoma and hepatocarcinoma foci was performed. METHODS: During hepatocarcinogenesis of F344 rat induced by 3'-methyl-4-dimethylamino-azobenzene (3'-Me-DAB), the levels of these mRNAs were quantitatively analyzed by LightCycler V3 System real-time RT-PCR after capturing accurately micro-foci in prehepatocarcinoma and hepato-carcinoma of rats with laser capture microdissection (LCM). RESULTS: At the 6th, 12th and 24th experiment weeks, the p53 mRNA levels in all of prehepatocarcinoma foci were markedly higher than those in the adjacent normal tissues (all of P < or = 0.001), and gradually decreased from the 6th week to the 24th week (P < 0.01). The content of p53 mRNA in hepatocarcinoma foci was higher than that in normal tissue (P = 0.028 and 0.013), but lower than that in prehepatocarcinoma foci. At 24th weeks, the sections of livers exhibited intensive immunostaining of p53 protein in prehepatocarcinoma and hepatocarcinoma foci. At any time-point of experiment, GST-P mRNA levels in prehepatocarcinoma foci were significantly higher than those in the adjacent normal liver tissue and hepatocarcinoma foci (all of P < 0.001). The concentration of AFP mRNA was the highest (P < 0.001) and that of albumin mRNA was the lowest (P < 0.01) in hepatocarcinoma foci as compared with adjacent normal tissue and prehepatocarcinoma foci. The GST-P protein and AFP protein were expressed strongly in prehepatocarcinoma and hepatocarcinoma foci, respectively. CONCLUSION: GST-P and AFP mRNA overexpressed in prehepatocarcinoma and hepatocarcinoma foci respectively will be profitable markers for diagnosis during hepatocarcinogenesis. The p53 mRNA highly expressed at early stage of prehepatocarcinoma and hepatocarcinoma, but the increasing concentration of p53 protein was found at later stage.

Actins↗

PubMed2003

[The application of denaturing high performance liquid chromatography in detection of novel polymorphisms in PAI-1gene].

OBJECTIVE: To detect single nucleotide polymorphisms(SNPs) in codon region of plasminogen activator inhibitor-1 (PAI-1) gene and associate them with development of coronary artery disease(CAD). METHODS: Denaturing high performance liquid chromatography(DHPLC) and DNA sequencing were used to scan all of exons in PAI-1 gene in 93 CAD patients and 123 control subjects. RESULTS: Two polymorphisms in exon 2, G43A and G49A, which results in missense mutation Ala15Thr and Val17Ile, were found. Heterozygotes for these variants as well as wild type homozygotes were only found in all subjects. The association of genotypes with CAD development and with PAI 1 antigen level were evaluated. The comparison of genotype frequency distribution between two groups revealed that there were more heterozygous carriers of mutation at both polymorphic sites in control than in CAD subjects, but there was no statistically significant difference between them. And genotypes of both polymorphisms were not associated with PAI-1 level. CONCLUSION: Two SNPs in exon 2 of PAI-1 gene were identified by DHPLC method. Both polymorphisms were not associated with the incidence of CAD.

Aged↗

PubMed2002

The origin and genetic diversity of Chinese native chicken breeds.

The first 539 bases of mitochondrial DNA D-loop region of six Chinese native chicken breeds (Gallus gallus domesticus) were sequenced and compared to those of the red junglefowl (Gallus gallus), the gray junglefowl (Gallus sonneratii), the green junglefowl (Gallus varius) and Lafayette's junglefowl (Gallus lafayettei) reported in GenBank, and the phylogenetic trees for the chickens were constructed based on the D-loop sequences. The results showed that the four species of the genus Gallus had great differences among each other the G. g. domesticus was closest to the red junglefowl in Thailand and its adjacent regions, suggesting the Chinese domestic fowl probably originatedfrom the red junglefowl in these regions. The two subspecies of Thailand, G. g. gallus and G. g. spadiceus, should belong to one subspecies because of their resemblance. In the case of native breeds, there existed a great difference between the egg breeds and general purpose breeds, which suggested different maternal origins of the two types.

Animals↗

PubMed2002

[Study on the properties of solid substrate room temperature phosphorescence of the antibody labeled with fluorescein isothiocynate].

The properties of room temperature phosphorescence (RTP) of the labeled goat anti-human antibody(with fluorescein isothiocynate GAHAb-FITC) and labeled rabit anti-goat antibody(RAGAb-FITC) with FITC in different dilution ratios on many kinds of solid substrates were studied in detail. It is found that on the polyamide membrane, only using Pb(Ac)2 as a heavy atom perturber, both the labeled antibodies and their antigen-antibody conjugated compound with the human immunoglobulin G remained excellent RTP properties of isothiocyanate fluorescein, lambda ex(max)/lambda em(max) = 525/650 nm, the relation of RTP intensity to the concentration was linear in a certain range. The conditions for immunological reaction and RTP emission were optimized. The result means that it is possible to develop a new immunoassay named as solid substrate room temperature phosphorescence immunoassay (SS-RTP-IA), which combines both the specificity of immunological reaction and high sensitivity of luminescence analysis.

Animals↗

PubMedDate not supplied

Diversity of endogenous small non-coding RNAs in Oryza sativa.

Small non-coding RNAs play important roles in regulating cell functions by controlling mRNA turnover and translational repression in eukaryotic cells. Here we isolated 162 endogenous small RNA molecules from Oryza sativa, which ranged from 16 to 35 nt in length. Further analysis indicated that they represented a diversity of small RNA molecules, including 17 microRNAs (miRNAs), 30 tiny non-coding RNAs (tncRNAs) and 20 repeat-associated small interfering RNAs (rasiRNAs). Among 17 miRNAs, 13 were novel miRNA candidates and their potential targets were important regulatory genes in the rice genome. We also found that a cluster of small RNAs, including many rasiRNAs, matched to a nuclear DNA fragment that evolutionarily derived from chloroplast. These results demonstrate clearly the existence of distinct types of small RNAs in rice and further suggest that small RNAs may control gene regulation through diverse mechanisms.

Base Sequence↗