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Biomedical subjects

F Qian

Publications and source records attributed to F Qian.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Expression of S.sonnei form I antigen gene and V.cholerae toxin B subunit gene in S.flexneri 2a strain and investigation of their immunoprotective response in mice].

The genes encoding S. sonnei form I O antigen and V. cholerae B subunit were cloned into an expression vector containing asd gene of Streptococcus mutans by gene recombination. The final recombination plasmid was transformed into the asd mutant of S. flexneri 2a (strain T32). Analysis of LPS silver staining and western blotting indicated that the genes encoding CT-B and form I O antigen could stably express in the asd mutant T32 strain. Immune protection tests in mice showed that the recombinant strain constructed in this study could provide 100% protection against the challenge from S. flexneri 2a and S. Sonnei and also showed a good immune protection (70%) against V. cholerae. This recombinant strain has the following advantages: trivalent, stable and no vector drug resistance markers.

Animals↗
PubMed1995

Chromosomal localization of the four genes (NFIA, B, C, and X) for the human transcription factor nuclear factor I by FISH.

Nuclear Factor I (NFI) proteins constitute a family of dimeric DNA-binding proteins with very similar, possibly identical, DNA-binding specificity. They function as cellular transcription factors and as replication factors for adenovirus DNA replication. Diversity in this protein family is generated by multiple genes, differential splicing, and heterodimerization. To determine the chromosomal position of NFI genes in the human genome, we isolated partial cDNA sequences derived from four independent genes: NFIA, NFIB, NFIC, and NFIX. Corresponding clones of genomic DNA served as probes for fluorescence in situ hybridization on human metaphase chromosomes. The NFIA and NFIB genes map to positions 1p31.2-p31.3 and 9p24.1, respectively. The NFIC and the NFIX genes were both localized to position 19p13.3 in the order centromere-NFIX-NFIC-telomere. Comparison of the position of NFI genes and JUN genes revealed a close physical linkage between members of the NFI and JUN gene families in the human genome.

Amino Acid Sequence↗
PubMed1995

Increased transcript levels of a methionine synthase during adhesion-induced activation of Chlamydomonas reinhardtii gametes.

Chlamydomonas gametes of opposite mating types interact through flagellar adhesion molecules called agglutinins leading to a signal transduction cascade that induces cell wall loss and activation of mating structures along with other cellular responses that ultimately result in zygote formation. To identify molecules involved in these complex cellular events, we have employed subtractive and differential hybridization with cDNA from mt+ gametes activated for fertilization and non-signaling, vegetative (non-gametic) cells. We identified 55 cDNA clones whose transcripts were regulated in activated gametes. Here we report the molecular cloning and characterization of the complementary DNA (cDNA) for one clone whose transcripts in activated gametes were several-fold higher than in normal gametes. Regulation of the transcript was not related simply to protein synthesis because it was not increased in cells synthesizing new cell wall proteins. The cDNA contained a single open reading frame (ORF) of 815 amino acids encoding a polypeptide of calculated relative mass of 87 kDa. Database search analysis and sequence alignment indicated that the deduced amino acid sequence exhibited 42% identity and 62% similarity to a class of prokaryotic methyl transferases (5-methyltetrahydrofolate-homocysteine methyl transferase; EC 2.1.1.14) known to be involved in the terminal step of de novo biosynthesis of methionine. This enzyme catalyzes transfer of a methyl group from 5-methyltetrahydrofolate to homocysteine resulting in methionine formation. Affinity-purified polyclonal antibodies raised against a bacterially produced GST-fusion protein identified a 85 kDa soluble protein in Chlamydomonas gametes. Southern blot hybridization indicated that the enzyme is encoded by a single-copy gene. The evidence presented in this paper raises the possibility that, in addition to its participation in de novo biosynthesis and regeneration of methionine, Chlamydomonas methionine synthase may play a role in adhesion-induced events during fertilization.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1995

Delayed dystonia with striatal CT lucencies induced by a mycotoxin (3-nitropropionic acid).

We describe a clinical syndrome of delayed dystonia in children subsequent to initial gastrointestinal symptoms and acute noninflammatory encephalopathy. The syndrome was caused by the ingestion of mildewed sugarcane containing the Arthrinium-produced mycotoxin, 3-nitropropionic acid (3-NPA). In the severely affected patients, intoxication usually was heralded by coma, with dystonia appearing 7 to 40 days after recovery from the coma. The dystonia was manifested as choreoathetosis, torsion spasms, or painful paroxysmal spasms of the extremities and was neither progressive nor reversible. CTs of the dystonic patients consistently showed bilateral hypodensities in the lenticular nuclei. The pathogenesis of the selective lenticular lesions induced by 3-NPA is not yet clear.

Carbohydrates↗
PubMed1994

Transcriptional regulation of cathepsin B expression in B16 melanomas of varying metastatic potential.

The highly metastatic B16a melanoma has been shown to express higher levels of cathepsin B (CB) mRNA when compared to the less metastatic variants, B16-F1 and B16-F10, and with normal mouse tissues. This increased expression is now shown to be due to increased gene transcription by nuclear run-off assays and measurements of mRNA stability. Transient expression assays, using promoter fragments from the mouse and human CB genes, demonstrated that both promoters were more active in B16a than in the less metastatic melanomas, B16-F1 and B16-F10. The differential gene expression did not depend on the presence of multiple Sp1 sites in both promoters. A Gel shift assay revealed a specific CB promoter binding protein whose levels are correlated with CB expression and the metastatic potential of the three B16 melanoma variants. These results indicate that the increased expression of CB in the B16a melanoma is due to a specific increase in the amount or activity of a transcriptional activator of the CB gene. The ability of the human CB promoter to activate gene expression in B16a melanoma cells suggests similarities in the regulation of CB expression in tumors from humans and mice.

Animals↗
PubMed1994

Expression of the integrin alpha 4 beta 1 on melanoma cells can inhibit the invasive stage of metastasis formation.

Among a series of adhesion molecules, expression of integrin alpha 4 beta 1 showed a unique inverse correlation with the invasive potential of B16 melanoma cell lines. When an alpha 4 cDNA was introduced into an alpha 4-beta 1+ highly invasive melanoma line, alpha 4 beta 1 heterodimers were expressed on the surface. Matrigel invasion by the alpha 4+ beta 1+ cells was reduced. Pulmonary metastasis was also suppressed when the transfectants were placed subcutaneously, but not when injected intravenously. Expression of alpha 4 beta 1 promoted homotypic intercellular adhesion. The homotypic adhesion was abrogated, and the alpha 4+ beta 1+ (less invasive cell lines) increased matrigel invasion following the anti-alpha 4 MAb treatment. These results suggest that integrin alpha 4 beta 1 could play a role in controlling melanoma cell metastasis at the invasive stage.

Animals↗
PubMed1994

Excimer laser deposition of hydroxyapatite thin films.

We have demonstrated a new and simple in situ method to fabricate adherent and dense hydroxyapatite (HA) coatings at relatively low deposition temperatures (500-600 degrees C). Under optimum processing conditions, the HA coatings possess a nominal Ca:P ratio of 1.65 and exhibit a fully crystalline single-phase structure. This deposition technique is based on the application of a pulsed excimer laser (wavelength lambda = 248 nm, pulse duration tau = 25 x 10(-9) s) to ablate a dense stoichiometric HA target. The HA target was prepared by standard ceramic coprecipitation techniques followed by cold pressing and further sintering at 1200 degrees C in air. High substrate temperatures (> or = 600 degrees C) during film deposition led to phosphorus deficient coatings because of re-evaporation of phosphorus during the deposition process. The stabilization of various calcium and phosphorus phases in the film was controlled by a number of process parameters such as substrate temperature, chamber pressure and presence of water vapour in the chamber. This is particularly advantageous for production of HA coatings, since it is known that HA decomposes at high temperatures due to the uncertainty in the starting material stoichiometry. Rutherford backscattering spectrometry, energy dispersive X-ray analysis, transmission electron microscopy, scanning electron microscopy and X-ray diffraction techniques were employed to determine the structure-processing relationships. Qualitative scratch measurements were conducted to determine the adhesion strength of the films.

Calcium↗
PubMed1992

The -6.1-kilobase chicken lysozyme enhancer is a multifactorial complex containing several cell-type-specific elements.

In the chromatin domain of the chicken lysozyme gene of myeloid and oviduct cells, which both have the potential to activate the gene, a developmentally stable DNase I-hypersensitive site is formed around 6.1 kb upstream of the gene. This implies that this DNA region, which has previously been demonstrated to function as a transcriptional enhancer element in myeloid cells, is intimately involved in the cell-type-specific activation of the lysozyme gene locus. Deletion analysis identifies a 157-bp minimal fragment that confers the same promacrophage-specific enhancer activity as the originally described 562-bp -6.1-kb enhancer fragment. By introducing specific point mutations, we demonstrate in transient gene transfer experiments that the minimal fragment consists of at least six adjacent elements, each substantially contributing to enhancer function. The compact multifactorial enhancer complex includes a nuclear factor I (NF-I)/TGGCA binding site, homologies to AP1, and octanucleotide or enhancer core consensus motifs. Point mutation of the NF-I binding site results in the loss of NF-I binding in vitro and enhancer activity in vivo after gene transfer. Surprisingly, four overlapping oligonucleotides, each consisting of at least two elements of the -6.1-kb enhancer, confer myeloid-cell-specific enhancer activity. We found several myeloid-cell-specific DNA-binding proteins interacting with the -6.1-kb enhancer, a result consistent with that described above. Therefore, we suggest that more than a single trans-acting factor mediates the cell type specificity of the -6.1-kb enhancer.

Animals↗
PubMed1992

Hemodynamic assessment of intravenous Isosorbidi Dinitras in coronary heart disease.

This study investigates the systemic hemodynamic effects of intravenous Isosorbidi Dinitras, Isoket (ISDN) in 20 patients with coronary arterial disease to test the validity of the hypothesis concerning the relief of myocardial ischemia. Patients were eligible for the study if they had angina with coronary angiographic records or if they were cases of post-myocardial infarction. Before and after ISDN infusion the following measurements were recorded or calculated: heart rate (HR); systolic, diastolic and mean aortic pressure (ASP, ADP, AP); systolic and mean pressure of the left ventricle (LVSP, LVP); end-diastolic pressure in the LV (LVEDP); left ventricular contractility (dp/dt max); the double products (DP, HR x LVSP) and myocardial perfusion pressure in the LV (LVPP). After ISDN the ASP, AP and LVEDP decreased while HR, ADP, dp/dt and DP showed no significant changes. However, LVEDP was significantly decreased from 20 +/- 7 to 12 +/- 5 mmHg (P less than 0.01) with increased LVPP from 49 +/- 12 to 56 +/- 13 mmHg (P less than 0.01), which may be favourable for the relief of myocardial ischemia. There was no significant change of dp/dt max with decreased LVEDP after ISDN. It is suggested that the left ventricle can maintain normal performance at lower intracardial volume (preload) in these patients.

Adult↗
PubMed1991

The structure of the mouse cathepsin B gene and its putative promoter.

The mouse cathepsin B gene and its flanking regions were cloned and characterized. The gene contains 10 exons and 9 introns spanning about 20 kb. Although the exon-intron organization of the mouse cathepsin B gene showed some similarity to the rat cathepsin H and L genes, significant differences were found. In particular, the highly conserved sequence that contains the catalytically active cysteine in these genes is split at different sites by an intron. As with other thiol proteinases, there is no obvious correspondence between the coding exons and structural or functional units within preprocathepsin B. These results suggest that the lysosomal thiol proteinase genes are evolutionarily ancient and that intron shifting has occurred subsequent to their divergence from a common ancestral form. The 5'-flanking region and exon 1 sequences in the mouse cathepsin B gene have a high GC content of approximately 72%. The 5'-flanking region also contains several potential Sp1 binding sites, but lacks TATA and CAAT motifs. These characteristics suggest that cathepsin B is a "housekeeping" gene and its transcription may be controlled by multiple transcription factors, including Sp1.

Amino Acid Sequence↗
PubMed1991

The expression of cathepsin B and other lysosomal proteinases in normal tissues and in tumors.

The mRNA for the lysosomal proteinases cathepsins B, D, H, L, and S are broadly distributed in normal rodent tissues. Although total cathepsin mRNA levels generally parallel the protein catabolic activity of the tissues, the expressions of the individual enzymes do not appear to be linked. Thus, the relative proportions of the individual messages are found to vary from tissue to tissue. Further evidence for the independent regulation of lysosomal proteinase expression is derived from observations of selective increases in mRNA levels for individual proteinases in rodent tumors. Only cathepsin B mRNA is elevated in a highly metastatic murine B16a melanoma and in a Walker-256 rat carcinosarcoma, while Moloney murine sarcoma virus-transformed fibroblasts express increased mRNA for cathepsins B, D, and L and normal levels for H and S. To address the regulation of cathepsin B expression, the mouse cathepsin B gene and its 5'-upstream region were cloned. The gene has 10 exons and 9 introns spanning about 20 kilobases. The 5'-upstream region and exon 1 are GC-rich with several potential Sp1 binding sites. TATA and CAAT motifs adjacent to the transcription start site are not evident. These properties are characteristic of mammalian "housekeeping" genes. B16 melanoma cells contain three cathepsin B transcripts of 2.2, 4.0 and 5.0 kilobases. The two larger messages, which were not found in normal tissues, contain unusually long 3'-untranslated regions resulting from the alternative cleavage and polyadenylation of the 3' end of the cathepsin B pre-mRNA in B16 melanomas. As all three messages encoded normal preprocathepsin B, cathepsin B secretion by melanoma cells is probably due to posttranslational mechanisms and not to alternative splicing or gene mutation.

Animals↗
PubMed1990

Molecular cloning of rat precursor cathepsin H and the expression of five lysosomal cathepsins in normal tissues and in a rat carcinosarcoma.

1. A rat cathepsin H cDNA was isolated from a rat liver cDNA library with synthetic oligonucleotide probes. 2. DNA sequence analysis indicated that it codes for rat preprocathepsin H. 3. Using this clone together with the cDNA for cathepsins B, D, L and S as probes, the expression of five major lysosomal proteinases was investigated in ten different normal rat tissues and in a rat carcinoma. 4. The common feature of their expression is that the five cathepsins have relatively high mRNA levels in lung and kidney, suggesting that they all play important roles in organs engaged in active protein metabolism. 5. In other tissues, the concentrations of the five cathepsin mRNAs are significantly different. This may indicate that their expressions are differentially regulated and that they may have specialized functions in specific tissues. 6. The cathepsin B mRNA level is at least 2.5-fold higher in the rat W256-carcinoma than in any of the normal rat tissues surveyed. 7. In contrast, the mRNA levels for the other four cathepsins show no comparable elevations. 8. This finding is consistent with previous observations reporting a correlation between cathepsins B expression and malignant tumors.

Amino Acid Sequence↗
PubMed1990

[Kalman filtering-titrimetry: potentiometric titration of benzalkonium bromide].

The application of Kalman filtering and smoothing to titrimetry has been investigated. The method is suitable for titration systems in both thermodynamic equilibrium and non-equilibrium (dynamic). Particularly, Kalman filtering and smoothing can give correct results in cases when other traditional methods failed. The effect of model noise, titration rate and sampling time was also examined on the accuracy of the filtering titrimetry. The proposed method has been applied to potentiometric titration and rapid determination of benzalkonium bromide.

Benzalkonium Compounds↗
PubMed1989

Expression of five cathepsins in murine melanomas of varying metastatic potential and normal tissues.

The relative levels of mRNAs for cathepsins B, D, H, L, and S in eight normal murine tissues and three murine melanoma variants, B16-F1, B16-F10, and B16a, have been analyzed by RNA dot blot and densitometry. A direct correlation was observed between the levels of cathepsin B mRNA and the metastatic potentials of these three melanoma variants. The relative amount of cathepsin B mRNA in B16a, which is the melanoma variant with the highest metastatic potential, was at least 3 times greater than that found in any of the normal murine tissues surveyed. Similar results were obtained in analyses of either solid tumors or of cultures of tumor cells, confirming that the tumor cells themselves were the source for the elevated expression of cathepsin B mRNA. Northern blot analysis revealed the presence of three cathepsin B transcripts of 5.0, 4.0, and 2.2 kilobases in the melanoma variants, while only the 2.2-kilobase transcript was seen in the normal murine tissues. Concurrently with the mRNA analysis, enzyme assays for cathepsin B activity were also performed using synthetic peptide substrates. The assays revealed increased cathepsin B activities in the melanoma variants, corresponding well with the increased cathepsin B mRNA levels, and in addition demonstrated that all three of the melanoma variants secreted a latent form of cathepsin B into conditioned medium, which could be activated by limited proteolysis with pepsin. The levels of the latent enzyme released by the murine melanoma variants correlated well with the levels of cathepsin B mRNA and with the metastatic potentials as determined by spontaneous metastasis form a s.c. site.

Animals↗
PubMed1989

[Determination of flecainide concentration in blood plasma by HPLC and pharmacokinetic parameters in volunteers].

A high performance liquid chromatographic method (ultraviolet detection) for the determination of flecainide concentration in human plasma was reported. Flurazepam (dalmadorm) was used as the internal standard. A mixture of methanol and deionized water containing ion paired reagent served as the mobile phase. The regression equation of flecainide was: y = 0.0017x + 0.0131, r = 0.9975. The extraction recoveries exceeded 94%, and the coefficients of variation (both within the same day and in different days) were less than 5%. The pharmacokinetic parameters in Chinese volunteers after taking flecainide were: Ka = 0.908h-1, T1/2 = 8.131h, peats time = 3.487h, AUC = 441.8ng.h/ml. The mean plasma concentration of flecainide in cases responded well to this drug was 423.6 +/- 227.4ng/ml.

Adult↗
PubMed1989

Radioimmunotherapy for hepatocellular carcinoma (HCC) using 131I-anti HCC isoferritin IgG: preliminary results of experimental and clinical studies.

Based on radioimmunoimaging for HCC using 131I-anti HCC isoferritin IgG, the experimental and clinical studies on radioimmunotherapy for HCC were reported. Thirty-six nude mice bearing human HCC were used for the study of labeled IgG, pure 131NaI and pure IgG. In the labeled IgG group, the tumor inhibition rate was significantly higher than that in other groups (81%, 60%, and 18%, respectively, p less than 0.05). The tumor cell DNA analysis showed the tumor cell was inhibited in the S stage of the cell cycle. Twenty pathologically proven unresectable HCC patient were treated by 131I-antihuman HCC isoferritin IgG 20-55mCi monthly for 1-3 times (via hepatic arterial catheter or intravenously). The short-term response was promising, a decline in AFP level and shrinkage of tumor were observed in 80% (12/15) and 65% (13/20) of patients respectively. Sequence resection was successful in five patients (5/20) after radioimmunotherapy. No marked toxic effects were noted in our limited experience, but some problems remain to be discussed.

Adult↗