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Biomedical subjects

J Fu

Publications and source records attributed to J Fu.

At least 181 records · Page 10Linked to original sources
PubMed1997

Epidermal growth factor reduces L-type voltage-activated calcium current density in GH4C1 rat pituitary cells.

Long-term treatment of rat pituitary tumor cells with epidermal growth factor (EGF) inhibits 45Ca2+ uptake, intracellular calcium levels and subsequent prolactin secretion in response to membrane depolarization. In the present study we have used whole-cell voltage-clamp and single-channel patch-clamp recording to determine directly the effects of EGF (10 nM for 48 h) on L-type calcium current density, the current-voltage relationship, single-channel amplitude, and opening and closing dwell times in rat GH4C1 pituitary tumor cells. Sustained, nimodipine-sensitive inward currents (barium as the carrier) with an activation threshold of approximately -30 mV were elicited in both control and EGF-treated GH4C1 cells by depolarization. Mean current density normalized to membrane capacitance was reduced to 45% of control after EGF treatment. There was no difference in the voltage-dependent activation of L-type channels between control and EGF-treated cells. Analysis of single-channel current recordings showed that EGF treatment had no effect on unitary current amplitude or channel open and close durations. These results suggest that EGF reduces the number of voltage-gated calcium channels in GH4C1 cell membranes, which likely contributes to the decreased calcium uptake.

Animals↗
PubMed1997

Epitope analysis of human T-cell response to MSP-1 of Plasmodium falciparum in malaria-nonexposed individuals.

BACKGROUND: MSP-1 of Plasmodium falciparum induces strong proliferative T cell responses even in malaria-nonexposed individuals. Epitopes recognized by malaria-nonimmune T cells have not been identified, and immunological mechanisms inducing such T cell responses remain to be uncovered. MSP-1 is a vaccine candidate, and it should be understood whether those epitopes have any roles in MSP-1-mediated protective immunity. The T epitopes-inducing malaria-naive T cell response was analyzed in the hope of understanding the underlying mechanisms. METHODS: Human T cell lines and clones reactive to MSP-1 of P. falciparum were established from malaria-nonexposed Japanese donors in vitro, and epitope peptides were identified. Sequences of those epitope peptides were compared to unrelated peptides in the data base. One of those peptides was tested for both binding to HLA-DR molecules and inducing proliferative responses of MSP-1-reactive T cells. RESULTS: There are at least 6 epitopes recognized by malaria-naive T cells under the restriction by HLA-DRB1*1502 or 0802. Important amino acids for the T cell recognition were identified for an MSP-1 peptide. A yeast peptide which shared those residues induced proliferative responses of MSP-1-reactive T cells. CONCLUSION: We identified T epitopes in the N-terminal region of MSP-1, some of which showed molecular similarities with unrelated environmental antigens, suggesting the presence of cross-reactive T epitopes in MSP-1. Cytokine production in response to those epitopes suggests regulatory functions of those T cells during primary infection with P. falciparum.

Amino Acid Sequence↗
PubMed1997

[Interleukin-6 behaves as an autocrine growth stimulator for a human lung giant cell carcinoma cell line].

OBJECTIVE: To study the effect of interleukin-6 (IL-6) on the growth of human pulmonary giant cell carcinoma cell line PG in vitro. METHODS: IL-6 mRNA level was detected by means of reverse transcriptase polymerase chain reaction (RT-PCR) and IL-6 receptor (IL-6R) mRNA was analyzed using Northern blotting hybridization. The production of IL-6 was detected by bioactive assay. The biological role of IL-6 produced by PG cells was assessed with anti-IL-6 neutralizing antibodies. RESULTS: PG cells expressed IL-6R mRNA. Recombinant human IL-6 promoted the proliferation of PG cells. PG cells also expressed IL-6 mRNA and produced bioactive IL-6. Treatment of PG cells with anti-IL-6 antibodies resulted in reduced growth of PG cells. CONCLUSION: The results indicate that IL-6 behaves as an autocrine growth stimulator for PG cells in vitro.

Antibodies↗
PubMed1997

[The inhibitory effect of antisense interleukin-6 on the growth of human lung carcinoma cells in vivo].

OBJECTIVE: Interleukin-6 (IL-6) has previously been implicated as a potential positive autocrine regulator of a human lung carcinoma cell lince PG. The purpose of the present study is to further evaluate the role of IL-6 in PG cells in vivo. METHODS: An antisense expression vector for IL-6 was constructed and introduced into PG cells. Antisense mRNA of IL-6 was detected by RNA-RNA dot blotting analysis. The production of bioactive IL-6 was measured by bioassay method. To determine the effect of antisense IL-6 cDNA on tumorigenicity, PG cells were inoculated subcutaneously into nude mice. RESULTS: Four transfectants, PGTAS1, PGTAS6, PGTAS8, PGTAS9, could express IL-6 antisense mRNA and secret decreased bioactive IL-6. The growth rate of 4 transfectants revealed was reduced in vitro. Comparing with the mice injected with the control PGTneo cells, the latent period of the mice inoculated with PGTAS6, PGTAS8, PGTAS9 cells was significantly increased, and the growth rate of the tumors was obviously decreased. The tumor size was markedly smaller. There was a negative correlation between the growth-inhibiting effect of IL-6 antisense gene and the amount of IL-6 secretion. CONCLUSION: These results indicate that IL-6 can function as an autocrine stimulator for PG cells in vivo as well as in vitro.

Animals↗
PubMed1997

[Color Doppler imaging analysis of ocular hemodynamics in low-tension glaucoma].

OBJECTIVE: To investigate ocular hemodynamics with color Doppler imaging, in low-tension glaucoma. METHODS: Nineteen patients with low-tension glaucoma (LTG) and 15 normal subjects were studied. The peak systolic velocity (Vmax), the end diastolic velocity (Vmin), the mean-enveloped velocity (Vmean), the pulse index (PI), the resistance index (RI) and S/D (Vmax/Vmin) of the ophthalmic artery (OA), the short posterior ciliary arteries (SPCA) and the central retinal artery (CRA) were compared in the two groups. RESULTS: (1) Compared with the normal subjects, the patients with LTG showed a decreased Vmax and Vmin in SPCA in bilateral eyes and Vmean in the right eye (P < 0.05), and a decreased RI and S/D in the left eye (P < 0.05). (2) Vmax and Vmean of CRA in LTG were lower than that in normal subjects (P < 0.01). (3) All six blood flow parameters of OA in the two groups were not significantly different from each other. CONCLUSIONS: Blood flow velocity of SPCA in LTG was lower than that in the normal subjects. The results support the theory that LTG is induced by the perfusion impairment of optic nerve head.

Aged↗
PubMed1997

[Interleukin-6 functions as an autocrine growth stimulator for a human lung adenocarcinoma cell line PAa].

OBJECTIVE: To study the effect of interleukin-6(IL-6) on the growth of a human lung adenocarcinoma cell line PAa in vitro. METHODS: IL-6 receptor (IL-6R) mRNA level was detected by means of reverse transcription polymerase chain reaction (RT-PCR) and IL-6 mRNA was analyzed using Northern blotting hybridization. The production of IL-6 was detected by bioassay. The biological effect of IL-6 released by PAa cells was assessed with anti-IL-6 neutralizing antibodies. RESULTS: PAa cells expressed IL-6R mRNA. Recombinant human IL-6 stimulated the proliferation of PAa cells. PAa cells also expressed IL-6 mRNA and produced bioactive IL-6. Treatment of PAa cells with anti-IL-6 antibodies resulted in decreased growth of PAa cells. CONCLUSION: These results demonstrate that IL-6 acts as an autocrine growth stimulator for PAa cells in vitro.

Adenocarcinoma↗
PubMed1997

[A study on the significance of p53 gene mutation, P53 protein positive staining and PCNA staining].

After obtaining the results of p53 gene mutation by a silver staining method to polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis, P53 protein staining and proliferation cell nuclear antigen (PCNA) index by double-blind method, multivariate correlation analysis two by two showed that PCR-SSCP, P53 positive protein staining and PCNA index had markedly correlation not only in oral precancerous lesions (OPL) but also in primary sites and regional metastatic lymph nodes of oral squamous cell carcinomas (OSCC). This indicated that the nature of the three indexes was the same. After introducing the sex and age of patients which have been proved to be related to the initiation and development of OPL and OSCC according to other researchers and are easy to be obtained in clinics, multivariate discriminatory analysis was carried on and three groups of discriminatory equations were gotten about the pathological grading of OPL and OSCC and metastasis condition of OSCC. The accuracy of these equations was 82.5%, 78% and 80%, individually. This suggests that the equations have applicable potentiality already.

Carcinoma, Squamous Cell↗
PubMed1997

[Detection of minimal residual disease after allogeneic bone marrow transplantation in chronic myeloid leukemia].

OBJECTIVE: To detect minimal residual disease (MRD) after allogeneic bone marrow transplantation (allo-BMT) in chronic myeloid leukemia (CML). METHODS: M-bcr/abl mRNA was assayed by reverse transcriptase polymerase chain reaction (RT-PCR) in bone marrow cells from 46 successfully sibling marrow engrafted CML patients. RESULTS: About 70% of the patients achieved genetic complete remission in 3 months post allo-BMT. Four patients were M-bcr/abc mRNA positive at 1.5 to 2 months post allo-BMT and turned to be negative at 3 to 9 months post allo-BMT. One patient was still M-bcr/abl(+) after disease-free survival(DFS) for more than 6 years, while another one was M-bcr/abl(-) after DFS for more than 4 years. CONCLUSION: RT-PCR is so far the most sensitive method for MRD detection in CML, but its limitation should not be ignored.

Adolescent↗
PubMed1997

[Construction and expression of a functional chimeric murine-human antibody directing against human cross-linked fibrin].

OBJECTIVE: In order to reduce the immunogenicity of the murine antifibrin monoclonal antibody (MAb) SZ-63 to human beings. METHODS: First of all, the cDNA sequences encoding the constant regions of the murine kappa light chain and gamma 1 heavy chain in the SZ-63 MAb were substituted with the corresponding human genomic sequences. Then the constructed MAb was cloned separately into two selectable expression vectors, and the latter were transfected into mouse myeloma cells (SP2/0) one by one. RESULTS: ELISA, Western blot and competition experiment results showed that there was 0.8 approximately 1.0 mg/L of chimeric 63 IgG in the conditioned medium of selected cell lines, and the expressed IgG had higher antifibrin D-Dimer capability than that of the original MAb. CONCLUSION: The expressed chimeric antibody can be used as a targeting agent for thrombus imaging and treatment.

Animals↗
PubMed1997

[Molecular evolution of MHC DQA genes. I. The maintenance of interallelic divergence and the influence of GC content on gene structure].

The analyses of the proportion of synonymous and missense nucleotide substitution (PS and PN) in different exons, antigen recognition sites (ARS) and non-ARS of EN2 (NAEN2) of 23 alleles at MHC DQA loci in 7 mammal species gave rise to the following findings. (1) PN was about twice as much as PS in ARS among the alleles at DQA1 of any given species, i.e. 7 alleles at HLA-DQA1 or 8 alleles at IaAa this accords with overdominant selection; (2) PS showed more or less the same as PN in ARS among different loci (DQA1 or DQA2 in different species, or DQA1 and DQA2 in one species) or NAEN2 of all comparative pairs, this conforms the expectation of neutral selection; (3) In exon4 and exon3, not only was the substitution proportion extremely low, but also PS was much higher than PN (the ratio PS over PN is 19.5 in alleles at IaAa of mouse and 4 among alleles at different loci), this coincides obviously with purification selection. The analysis of GC content of MHC DQA showed that its peaks were in the regions corresponding to the middle bulks of some domains, that the highest and constant level was in exon4 and that GC content in the third codon position (GC III content) associates inversely with PS. These results indicate that the specified maintenance mechanisms of interallelic diversity relevant to their functions exist in given exons corresponding to some domains of the same MHC DQA locus and GC III content is an important factor in keeping the structure and function of gene under selection constraint. The method for estimating nucleotide substitution proportion was modified.

Alleles↗
PubMed1997

[Molecular evolution of MHC DQA genes. II. Phylogenetic analysis based on nucleotide substitution and SCU bias].

Phylogenetics of 23 alleles at MHC DQA loci in 7 mammalian species was studied based on their nucleotide (NT) substitution and synonymous codon usage (SCU) bias. (1) It was demonstrated that the NT substitution rates are 1.0 x 10(-9) NT/site/yr for exon2 and 1.3 x 10(-9) NT/site/yr for exon2-4 in a large time scale, which is similar to other nuclear genes, while for mouse and rat the rates are nearly twice as high as above mentioned. (2) The DQA locus diversity and their interallelic diversity developed long after the radiation of mammalian 80Mya (million years ago). The bovine counterpart, of, and with the same recent ancestor of ovine DQA2, remains to be discovered. HLA-DQA2 locus split from HLA-DQA1 ancestor at the time between 12 approximately 20 Mya while allele diversity of HLA-DQA1 emerged and developed from 24 Mya to less than 1 Mya. (3) The phylogenetic trees based on SCU divergence reflect the phylogenetics of MHC DQA genes quite well generally in a new respect and reveal that HLA-DQA2 has a distinctive SCU bias different from all other MHC DQA locianalyzed. It indicates that SCU statistics plays an important and unique role in phylogenetic analysis of orthologous genes. The method to estimate the SCU divergence and SCU similarity was improved in this research.

Animals↗
PubMed1997

[Growth regulatory mechanisms of recombinant human interleukin-6 on human lung carcinoma cell lines].

OBJECTIVES: To detect the activity of interleukin-6 (rhIL-6) on human lung cancer and the influences of recombinant human IL-6 (rhIL-6) on the in vitro growth of high-metastatic human lung giant cell carcinoma cell line PG and low-metastatic human lung adenocarcinoma cell line PAa. METHODS: The effects of rhIL-6 on the expressions of IL-6, IL-6R, c-myc, c-fos and c-jun mRNAs were analyzed by Northern blotting hybridization. RESULTS: rhIL-6 could stimulate the in vitro growth of both PG and PAa cells, in a dose-and-time-dependent manner. Both PG and PAa cells were shown to express IL-6 and IL-6R identified by reverse transcription PCR analysis. Northern blotting hybridization revealed that rhIL-6 up-regulated mRNA levels of IL-6, IL-6R and c-myc rather than those of c-fos and c-jun. CONCLUSION: These data suggest that rhIL-6 may promote the proliferation of human lung cancer cell lines PG and PAa, which might, at least partly, be related to the up-regulation of expressions of IL-6, IL-6R, c-myc gene transcript.

Adenocarcinoma↗
PubMed1996

RAGE and amyloid-beta peptide neurotoxicity in Alzheimer's disease.

Amyloid-beta peptide is central to the pathology of Alzheimer's disease, because it is neurotoxic--directly by inducing oxidant stress, and indirectly by activating microglia. A specific cell-surface acceptor site that could focus its effects on target cells has been postulated but not identified. Here we present evidence that the 'receptor for advanced glycation end products' (RAGE) is such a receptor, and that it mediates effects of the peptide on neurons and microglia. Increased expressing of RAGE in Alzheimer's disease brain indicates that it is relevant to the pathogenesis of neuronal dysfunction and death.

Alzheimer Disease↗
PubMed1996

Site-directed mutagenesis of residues in a conserved region of bovine aspartyl (asparaginyl) beta-hydroxylase: evidence that histidine 675 has a role in binding Fe2+.

The roles in catalysis of several residues in bovine aspartyl (asparaginyl) beta-hydroxylase that are located in a region of homology among alpha-ketoglutarate-dependent dioxygenases were investigated using site-directed mutagenesis. Previous studies have shown that when histidine 675, an invariant residue located in this highly conserved region, was mutated to an alanine residue, no enzymatic activity was detected. A more extensive site-directed mutagenesis study at position 675 has been undertaken to define the catalytic role of this essential residue. The partial hydroxylase activity observed with some amino acid replacements for histidine 675 correlates with the potential to coordinate metals and not with size, charge, or hydrophobic character. Furthermore, the increase in Km for Fe2+ observed with the H675D and H675E mutant enzymes can account for their partial activities relative to wild type. No significant changes in the Km for alpha-ketoglutarate (at saturating Fe2+) or Vmax were observed for these mutants. These results support the conclusion that histidine 675 is specifically involved in Fe2+ coordination. Further site-directed mutagenesis of other highly conserved residues in the vicinity of position 675 demonstrates the importance of this region of homology in catalysis for Asp (Asn) beta-hydroxylase and, by analogy, other alpha-ketoglutarate-dependent dioxygenases.

Amino Acid Sequence↗
PubMed1996

Recombinant dengue type 1 virus NS5 protein expressed in Escherichia coli exhibits RNA-dependent RNA polymerase activity.

The complete nonstructural NS5 gene of dengue type 1 virus, Singapore strain S275/90 (D1-S275/90) was expressed in Escherichia coli as a glutathione S-transferase (GST) fusion protein (126 kDa). The GST-NS5 fusion protein was purified and the recombinant NS5 protein released from the fusion protein by thrombin cleavage. The recombinant NS5 had a predicted molecular weight of 100 kDa and reacted with antiserum against D1-S275/90 virus in Western blot analysis. The purified recombinant NS5 protein possessed RNA-dependent RNA polymerase activity which was inhibited (>99%) by antibodies against the recombinant NS5 protein. The polymerase product was shown to be a negative-stranded RNA molecule, of template size, which forms a double-stranded complex with the template RNA.

Animals↗
PubMed1996

An easily constructed carbon fiber recording and microiontophoresis assembly.

Traditional multibarreled pipette electrodes are still widely used in microiontophoresis studies. Although better electrodes have been introduced, they are difficult and time-consuming to make. Construction of a carbon fiber recording and microiontophoresis assembly is described here. The construction of a carbon fiber electrode assembly is easy and carbon fibers have excellent characteristics for recording extracellular single unit activity. Signal-to-noise ratio of the carbon fiber electrode is maintained when combined with microiontophoresis. The electrode assembly can be used repeatedly, if cleaned properly, and it can be used to make marking lesions upon completion of an experiment.

Animals↗