Biomedical subjects

Z Luo

Publications and source records attributed to Z Luo.

At least 145 records · Page 8Linked to original sources

PubMed1997

[The experimental studies of immune response of antigen-extracted bovine cancellous bone grafting].

Xenogeneic bone grafting is an alternative to autogeneic bone grafting, but the intense immune rejection makes its clinical practice limited. We performed lymphocytes proliferation assay, enzyme-linked immunosorbent assay, and histological observation to evaluate the levels of cellular and humoral immunity, and the tissue reaction to the grafting of BALB/c mice receiving fresh bovine cancellous bone (FCB), antigen-extracted bovine massive cancellous bone (MCB), antigen-extracted bovine granular cancellous bone (GCB). Lymphocyte proliferation was increased in an early phase of the grafting and persisted for a long period in FCB group. Meanwhile higher levels of specific antibody were detected. In MCB and GCB groups, lymphocyte proliferation and specific antibody production were not ascended and no significant difference was observed between MCB and GCB groups in these immunological responses. There were no appreciable histologic signs of immune or foreign body reaction both in MCB and GCB groups. The results suggested that MCB, GCB were characterized less antigenicity and can be used as osteoconductive material or a carrier of bone growth factors.

Animals↗

PubMed1997

[Diagnosis and surgical management of 22 patients with congenital coronary artery fistula].

Twenty-two patients underwent surgical treatment of coronary artery fistulas. The right coronary artery was the most common vessel of origin (68.2%), and the most frequent drainage site was the right ventricle (45.4%). The operation was performed with the use of extracorporeal circulation in 21 patients. Only one patient underwent distal ligation without the use of extracorporeal circulation. The absence of operative mortality and severe postoperative complication provide clear indications for surgical treatment. In view of currently improved and standardized techniques of extracorporeal circulation, we believe that it should be employed routinely.

Adolescent↗

PubMed1997

[The immune response in rats immunized systemically by the surface protein antigen P1 from streptococcus mutans conjugated with procholeragenoid].

This study was carried out to observe the antibody responses in rats after they were immunized with the surface protein P1 of streptococcus mutans when a special adjuvant was used. Antigen P1 was conjugated covalently with procholeragenoid (PCG), and then Sprague Dawley rats were immunized with P1 or the conjugated antigen P1-PCG subcutaneously or intragastrically. Anti-P1 antibody level was assayed at different time points by ELISA. The results showed that the levels of anti-P1 SIgA antibody in saliva rose when P1-PCG was given subcutaneously or intragastrically; the antibody level following the subcutaneous injection was higher and lasted longer, compared with that following the intragastric administretion. The level of anti-P1 IgG antibody in serum only rose when the rats were immunized subcutaneously. These results implied that mucosal immune response or humoral immune response could be induced subcutaneously when PCG was used as an adjuvant.

Animals↗

PubMed1997

[Effects of specific antibodies against the cell surface protein P1 of streptococcus mutans MT 6R upon adhered streptococci].

The sera and saliva were obtained from BALB/C mice by injection of the cell surface protein P1 and Freud's adjuvant. High antibody titers were showed in the sera and saliva by an enzyme-linked immunosorbent assay. The cells of S. mutans (serotype c, e and f) adhered on saliva-coated hydroxyapatite could be detached by the antibodies of the protein P1 of S. mutans MT 6R including in the sera and saliva (P < 0.05), but the antibodies had no influence on the cells of S. cricetus AHT, S. sobrinus OMZ176, S. sobrinus 6715 and S. rattus BHT (P > 0.05).

Animals↗

PubMed1997

[Effects of different dilution of specific antibodies against the cell surface protein P1 of S. mutans MT 6R upon its adherence].

The sera and saliva were obtained from BALB/C mice by injection of the cell surface protein P1 and Freud's adjuvant. High antibody titers were showed in the sera and saliva by an enzyme-linked immunosorbent assay. Different dilution of the specific antibodies against the protein P1 of S. mutans had different inhibition effects on adhering of S. mutans MT 6R. Adherence of streptococcus mutans MT 6R on saliva-coated hydroxyapatite was reduced significantly by using sera and salivary antibodies in dilution of 1:1, 1:2, 1:4, 1:8, 1:16, 1:32 (P < 0.05).

Animals↗

PubMed1997

[Conjugation and identification of the surface protein antigen P1 from streptococcus mutans MT6R with the cholera toxin B subunit and procholeragenoid].

To make an effective antigen to prevent dental caries, the surface protein antigen P1(Ag I/II) was purified and identified by the rabbit anti-Ag I/II serum and was covalently conjugated to CTB and PCG by SPDP respectively. GM1-ELISA showed that both the conjugated P1-CTB and P1-PCG possess the ability to bind GM1 specifically without losing the antigenicity of P1. This results showed that the conjugated antigens could be used in the immune prevention against dental caries.

Antigens, Bacterial↗

PubMed1997

[A primary observation of the active immune prevention effects against dental caries using the streptococcus mutans surface protein P1 in rats].

To observe the anti-caries effects of a small dose of the surface protein antigen P1. The SD rats were immunized with P1-CTB and P1-PCG through IN (intranasal immunization) and IG (intragastric immunization). The results showed that caries was reduced heavily. There was no obvious difference between IN and IG. P1-CTB and P1-PCG can be used as an antigen to prevent the dental caries, but much further research work still need to do.

Animals↗

PubMed1997

[An animal model for the mucosal immunization with the surface protein antigen P1 from streptococcus mutans and immune enhancement of cholera toxin].

To study the immune enhancement of cholera toxin by developing an mucosal immune animal model, SD rats were immunized using different antigen composition through intragastric route (I.G). The results showed that the effects of immunization became stronger after P1 was conjugated to cholera toxin B subunit (CTB) or procholeragenoid (PCG). Even microgram dose of P1 could induce the rising of anti-P1 SIgA antibodies in the rat's saliva, but the antibodies risied little without this adjuvant. These implayed that the conjugation was much necessary in IG immunization. The immune enhancement of PCG was greater than that of CTB.

Animals↗

PubMed1997

[Determination of sulpride in human plasma by high performance liquid chromatography].

This paper describes a reliable method for the pharmacokinetic study of Sulpride in human plasma by reversed-phase high performance liquid chromatography. To compensate the loss of Sulpride during the extraction procedure we used an internal standard very similar in chemical structure and UV absorbance to those of Sulpride. The mobile phase was methanol-water-acetic acid (60:30:1) with a flow rate of 1.2 mL/min. A UV detector was used at 290 nm. The linear range was 5-100 mg/L and the detectable limit was 1.0 mg/L. The recovery and RSD were 97.95%-99.96% and 2.6%-5.1% respectively. The results showed that this method is a sensitive and accurate one which makes the pharmacokinetic study of Sulpride possible. If the concentration was too low to be detected by UV monitor, a fluorescence detector could be used with the excitation wavelength at 299 nm and emission at 342 nm. We analyzed the plasma samples from 30 day-treated psychotic patients and got the satisfactory results.

Antidepressive Agents↗

PubMed1997

[The protective role of heat shock gene expression on hydrogen peroxide induced pulmonary alveolar macrophages].

The aim of this study is to determine whether heat-induced heat shock gene expression in rat pulmonary alveolar macrophages (PAMs) would protect PAMs against hydrogen peroxide (H2O2)-mediated cell killing. In response to sublethal heat shock at 42 degrees C for 2 h, the cells synthesized heat shock protein 70 kD (HSP70) and other different molecular weight heat shock proteins, which were detected with gel electrophoresis after [35S]-methionin labeling cellular protein and Western blotting analysis in PAMs. Northern blot analysis showed the induction of HSP70 mRNA with heat shock treatment. Futhermore, with heat shock, there was a significant increment of survival cells after H2O2 (1,2,3 mmol.L-1, 45 min) exposure. This increase was blocked both by Cycloheximide and by Actinomycin D, and was associated with inhibition of synthesis of HSP70 protein and transcription of HSP70 mRNA. These results strongly suggest that expression of heat shock gene (especially HSP70 gene) plays an important role in the intracelluar mechanism of cytoprotection against H2O2 in rat PAMs.

Animals↗

PubMed1997

[The effects of deferoxamine on bovine pulmonary endothelial cell injury induced by hydrogen peroxide].

The effect of deferoxamine (DFX), the ferric iron chelator, on bovine pulmonary endothelial cell (BPAEC) injury induced by hydrogen peroxide (H2O2) was examined in vitro. It was found that, when compared with unpretreated cells, H2O2-induced the release of lactate dehydrogenase and the production of thiobarbituric acid reactive substances were decreased, at the meantime the cellular activites of catalase and superoxide dismutase were maintained in DFX (2 mmol.L-1) pretreated BPAECs challenged by 1 mmol.L-1 H2O2. These data indicate that DFX provided almost complete protection against H2O2-mediated cytotoxicity. This suggests that intracellular iron may play an essential role in the endothelial cell injury mediated by H2O2.

Animals↗

PubMed1996

Identification of multiple rabbit flavin-containing monooxygenase form 1 (FMO1) gene promoters and observation of tissue-specific DNase I hypersensitive sites.

We have cloned and partially characterized the rabbit FMO1 gene as a first approach to understanding mechanisms controlling its tissue-specific expression. The isolated clones contain 14 kb of 5' flanking information and approximately 30 kb of the structural gene, but do not include the 3'-end. Two upstream exons were defined, both encoding 5' leader information. The first exon, termed exon 0, contains information not previously reported. The second exon, termed exon 1, contains information previously reported for the rabbit FMO1 cDNA. Protein coding information begins seven nucleotides from the start of exon 2. A single transcription start site was localized in exon 1, while a cluster of sites were defined in exon 0, consistent with two alternative promoters. Transcripts initiating in exon 0 do not contain exon 1 information due to alternative processing and represent the major FMO1 mRNA. Neither promoter contains a TATA box or GC islands, although the exon 1 promoter does share some sequence identity with initiator-type elements. Homologous sequences to several known transcription factor binding sites were found in the upstream region of the FMO1 promoters. Both promoters were active in directing luciferase expression when transiently transfected into human HepG2 cells, although the data are consistent with both requiring upstream enhancer sequences. Consistent with this observation, DNase I hypersensitive sites were mapped to a 600-bp region immediately upstream of exon 0 using liver nuclei. No such sites were detected with nuclei from lung. Differential DNA methylation also was not observed between these two tissues.

Animals↗

PubMed1996

Involvement of p21cip-1 and p27kip-1 in the molecular mechanisms of steel factor-induced proliferative synergy in vitro and of p21cip-1 in the maintenance of stem/progenitor cells in vivo.

Steel factor (SLF) is a hematopoietic cytokine that synergizes with other growth factors to induce a greatly enhanced proliferative state of hematopoietic progenitor cells and factor-dependent cell lines. Even though the in vivo importance of SLF in the maintenance and responsiveness of stem and progenitor cells is well documented, the molecular mechanism involved in its synergistic effects are mainly unknown. Some factor-dependent myeloid cell lines respond to the synergistic proliferative effects of SLF plus other cytokines in a manner similar to that of normal myeloid progenitor cells from bone marrow and cord blood. We show here that SLF can synergize with granulocyte-macrophage colony-stimulating factor (GM-CSF) to induce an enhanced phosphorylation of the retinoblastoma gene product and a synergistic increase in the total intracellular protein level of the cyclin-dependent kinase inhibitor, p21cip-1, which is correlated with a simultaneous decrease in p27kip-1 in the human factor-dependent myeloid cell line, M07e. Moreover, these cytokines synergize to increase p21cip-1 binding and decrease p27kip-1 binding to cyclin-dependent kinase-2 (cdk2), an enzyme required for normal cell cycle progression; these inverse events correlated with increased cdk2 kinase activity. It is also shown that exogenous purified p21cip-1 can displace p27kip-1 already bound to cdk2 in vitro. These data implicate increased p21cip-1 and decreased p27kip-1 intracellular concentrations and their stoichiometric interplay in the enhanced proliferative status of cells stimulated by the combination of SLF and GM-CSF. In support of these findings, it is shown that hematopoietic progenitor cells from mice lacking p21cip-1 are defective in SLF synergistic proliferative response in vitro. Moreover, the cycling status of marrow and spleen progenitors and absolute numbers of marrow progenitors were significantly decreased in the p21cip-1 -/-, compared with the +/+ mice. We conclude that the cdk threshold regulators p21cip-1 and p27kip-1 play a critical role in the normal mitogenic response of M07e cells and murine myeloid progenitor cells to these cytokines and particularly in the SLF synergistic proliferative response that is important to the normal maintenance of the stem/progenitor cell compartment.

Animals↗

PubMed1996

Oligomerization activates c-Raf-1 through a Ras-dependent mechanism.

The c-Raf-1 proto-oncoprotein is a Ras-GTP-regulated protein kinase that associates in situ with 14-3-3 proteins, which are naturally dimeric. In COS cells, recombinant Raf is found in oligomeric assemblies. To examine whether induced oligomerization can alter Raf kinase activity, sequences encoding the FK506-binding protein FKBP12 were fused to the amino terminus of c-Raf-1, introducing a binding site for FK506. Oligomerization of recombinant FKBP-Raf in situ, induced by the addition of the dimeric FK506 derivative FK1012A, activated Raf kinase activity at least half as well as epidermal growth factor (EGF). As with EGF, activation of FKBP-Raf by FK1012A is entirely Ras-GTP dependent. Thus oligomerization of Raf per se promotes Raf activation through a Ras-dependent mechanism.

Biopolymers↗

PubMed1996

Induction of acetylcholine receptor gene expression by ARIA requires activation of mitogen-activated protein kinase.

Transcription of genes encoding nicotinic acetylcholine receptor (AChR) subunits (alpha, beta, gamma or epsilon, and delta) is highest in nuclei localized to the synaptic region of the muscle, which contributes to maintain a high density of AChRs at the postjunctional membrane. ARIA (AChR inducing activity) is believed to be the trophic factor utilized by motor neurons to stimulate AChR synthesis in the subsynaptic area. To elucidate the signaling mechanism initiated by ARIA, we established stable C2C12 cell lines carrying the nuclear lacZ gene under the control of the mouse epsilon subunit promoter or chicken alpha subunit promoter. ARIA stimulated tyrosine phosphorylation of erbB proteins in these C2C12 cells within 15 s with a peak at 5 min. Immediately following tyrosine phosphorylation of erbB proteins, mitogen-activated protein (MAP) kinase was activated which occurred within 30 s and peaked at 8 min after ARIA stimulation. Concomitantly, expression of AChR genes was induced by ARIA. ARIA-induced AChR subunit transgene expression was observed only in differentiated myotubes and not in myoblasts, suggesting that downstream signaling component(s) are regulated in a manner dependent on the myogenic program. Inhibition of the MAP kinase activity by using a specific MAP kinase kinase inhibitor or by overexpressing dominant negative mutants of Raf or MAP kinase kinase attenuated or abolished the ARIA-induced activation of AChR alpha and epsilon subunit gene expression. These results indicate that regulation of AChR gene expression by ARIA in C2C12 cells requires activation of the MAP kinase signaling pathway.

Androstadienes↗

PubMed1996

Role of an upstream open reading frame in mediating arginine-specific translational control in Neurospora crassa.

The Neurospora crassa arg-2 transcript contains an upstream open reading frame (uORF) specifying a 24-residue leader peptide and is subject to a novel form of negative translational regulation in response to arginine. The role of the arg-2 uORF in arginine-specific negative regulation was investigated by using translational fusions of wild-type and mutant arg-2 sequences to the Escherichia coli lacZ reporter gene specifying beta-galactosidase. The wild-type uORF conferred Arg-specific regulation on the reporter gene in N. crassa, but mutated or truncated uORFs did not, as determined by measurements of beta-galactosidase activity produced in N. crassa strains expressing arg-2-lacZ fusion genes. All effects on reporter gene expression were posttranscriptional, as determined by measurement of RNA levels. Both sequence-dependent and sequence-independent effects of uORFs were observed. Genes containing the wild-type uORF or a 21-codon mutated uORF showed reduced translation in comparison with that of a gene lacking a uORF. Both uORF-containing transcripts showed reduced association with polysomes relative to transcripts lacking a uORF, but only the transcript with the wild-type uORF showed a reduced average number of ribosomes associated with it in response to arginine addition. Direct translational fusions between uORF sequences and lacZ sequences indicated that the uORF is translated. Overlapping the uORF with the lacZ initiation codon indicated that ribosome reinitiation at a downstream start codon is not integral to uORF-mediated, Arg-specific translational regulation. These studies provide direct biochemical evidence for arg-2 uORF function in translational control.

Arginine↗

PubMed1996

A method for co-localization of tubular lysosomes and microtubules in macrophages: fluorescence microscopy of individual cells.

Routinely used procedures for chemical fixation often fail to preserve delicate membrane-bounded tubular structures in a variety of cell types. Fixation procedures commonly employed in immunocytochemical studies for localization of structural proteins, such as those found in cytoskeletal elements, may also degrade these tubular structures. Here we describe a procedure that preserves the elaborate tubular lysosome system found in stimulated macrophages and allows the subsequent immunofluorescence localization of microtubules in the same cells. Use of this methodology permits the assessment of the spatial relationship between tubular lysosomes and microtubules in macrophages.

Animals↗

PubMed1996

[Regenerating axons selectively reinnervate their target organs after the peripheral nerves were tubulated].

This study investigated target specificity during axonal regeneation of a mixed motor and sensory nerve after the canine tibial nerves were tubulated. 10mm gap of tibial nerve was connected by silicone tube. Three months later, the second operation was performed by spinal dorsal root ganglion (DRG) resection at the experimental side. Five months later, histalogical analysis results reveal that the regenerating motor nerve fibre of mixed nerve selectively grew into motor branches. The mean number of regenerated motor nerve fibers grew into its motor branches was 1199, and the number of that into its sensory branch was only 21. This result suggests that regenerating motor and sensory axons of mixed nerve can across 10-mm silicone chamber and be able to select their distal target organs exectly.

Animals↗