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Biomedical subjects

M Zhao

Publications and source records attributed to M Zhao.

At least 271 records · Page 15Linked to original sources
PubMed1996

Directed migration of corneal epithelial sheets in physiological electric fields.

PURPOSE: To characterize the effects of small applied electric fields (EFs) (100 to 250 mV/ mm) on cultured bovine corneal epithelial cell (CEC) sheets and to determine how EFs interact with other environmental cues in directing CEC sheet migration. METHODS: Primary cultures of bovine CECs were exposed to EFs in medium with or without serum, epithelial growth factor, basic fibroblast growth factor, or transforming growth factor-beta 1. Cell sheet migration was traced using an image analyzer. RESULTS: Cell sheets migrated toward the cathode (negative pole). The directional migration was voltage dependent, and, at low field strength (up to 200 mV/mm), it required serum in the medium. Sheets showed no migration responses up to 200 mV/mm in serum-free medium, whereas those in medium with serum showed evident migration toward the cathode, at an average rate of approximately 15 microns/h (n = 15 approximately 20) at 150 mV/mm. When serum was present, the threshold was below 100 mV/mm, very close to the measured wound field strength (approximately 42 mV/mm). After supplementing serum-free medium with individual growth factors or with combinations of epithelial growth factor, basic fibroblast growth factor, and transforming growth factor-beta 1, significant restoration of cathode-directed migration occurred at 150 mV/ mm. Lamellipodia were abundant at the leading edges of migrating sheets, extending the area of sheets covered. The extension of cell membranes toward the cathode was more prominent in cell sheets than in single cells. CONCLUSIONS: The endogenous EFs generated by wounded cornea could play an important role by interacting with other environmental factors to promote changes in shape and in directed migration of CEC sheets.

Animals↗
PubMed1996

Protective effect of interleukin-1 receptor antagonist on oleic acid-induced lung injury.

OBJECTIVE: To observe the changes of interleukin-1 (IL-1), nitric oxide (NO) and nitric oxide synthase (NOS) in mice with oleic acid-induced acute lung injury (ALI) and the protective effects of interleukin-1 receptor antagonist (IL-1ra). MATERIAL AND METHODS: Male Kunming mice were divided into control, oleic acid and IL-1ra groups. The control group mice were injected saline; the oleic acid group mice were injected oleic acid (0.2 ml/kg): and the IL-1ra group mice were injected the IL-1ra (20 mg/kg). Lung index, lung wet-to-dry weight ratio, and total protein, cell analysis, nitric oxide measurement, NOS activity in BALF, lung pathology examination were made after an hour of administration of drug. RESULTS: Preadministration of IL-1ra to the mouse with ALI decreased the lung index, lung wet-to-dry weight ratio and leakage of protein from pulmonary capillary, elevated PaO2, and attenuated lung histologic injury. It was found that in bronchoalveolar lavage fluid (BALF), NO amount and lung NOS activity increased in oleic acid group, BALF NO amount and lung NOS activity decreased obviously after given IL-1ra. CONCLUSIONS: This study demonstrated the protective effect of IL-1ra on oleic acid-induced lung injury, NO may participate in the pathological process of lung injury.

Animals↗
PubMed1996

[The PCR amplification, cloning, sequencing, expression in E. coli of gene encoding endoflagella subunit protein (fla B) from Leptospira interrogans serovar lai].

A pair of oligonucleotide primers were designed by ourselves to amplify the endoflagella gene of L. interrogans serovar lai. A fragment about 840 bp was generated with PCR and inserted into plasmid pUC8 after the fragment and pUC8 were digested respectively with Bam HI and Pst I. A recombinant plasmid (designated as pLF1) was obtained. SDS-PAGE analysis indicated that a 33 kd was expressed in E. coli JM103 harboring pLF1 and the expression level of the protein was 11% of total bacterial soluble proteins. Western blot analysis showed that the protein band could be recognized by the antiserum against the endoflagella (Axiall filament) of Leptospira interrogans serovar lai. Nucleotide seguence data showed an open reading frame encoding 282 aminoacids residues, corresponding to a protein of molecular weight 33.6 kd. The G + C content of endoflagella subunit protein gene was 48 mol%. Therefore, the G + C content of the leptospiral fla B Gene is significantly higher than the reported 39 mol% G + C content of leptospiral genome of L.interrogans serovar lai but similar to the G + C of the Treponema pallidum genome. Comparison of the deduced endoflagellar subunit protein (fla B) amino acid sequence with flagellins from other bacteria revealed a high level of identity with the Treponema pallidum fla B proteins. Immunization/protection experiment was performed on the model of BALB/c mice and showed that the survival rate in the group JM103-pLF1 was higher than that in the group JM103-pUC8, but statistically the difference between them was significant (P < 0.05) and pLF1 did not induce significant levels of agglutinating antibodies against L.interrogans serovar lai.

Amino Acid Sequence↗
PubMed1996

[Comparative observation on the relationship between the MEFV and the visual inspection of small airway].

OBJECTIVE: To compare the relationship between the MEFV and the visual inspection of small airway. METHODS: According to the result on small airway function test (MEFV), the patients were divided into two group: MEFV abnormal group and MEFV normal group. Their bronchus and peripheral airway were observed with bronchofiberscope and ultra-thin bronchofiberscope. The visual appearance of the airways was scored in the light of the presence or absence of erythema, edema, secretions, etc. RESULTS: The score of visual appearance observed or bronchitis index (BI) in small airway was 7.7 +/- 0.8 (BI: 3.0 +/- 0.8) and 4.7 +/- 1.6 (BI: 1.5 +/- 0.5) respectively in MEFV abnormal group and in MEFV normal group, namely the score in MEFV abnormal group was significantly higher than that of normal group (P < 0.01). The degree of pathological change in small airway was significantly correlated with the results of V25, V50, r = -0.6271, (P < 0.05) and r = 0.6964, (P < 0.02). CONCLUSION: The abnormal of MEFV may reflect inflamative pathological changes of small airway.

Asthma↗
PubMed1996

Surgical treatment of spinal tumor (analysis of 32 cases).

With the advance of spinal surgery in the last decade, surgical treatment of spinal tumors has been no longer limited to simple laminectomy. The principles of surgical treatment of spinal tumors include: (1) anterior approach for the anterior lesion and posterior approach for the posterior lesion; (2) combined anterior and posterior approach for extensive lesions and (3) internal fixation for spinal stability. 32 cases of spinal tumors were treated on the basis of the above guiding principles and 84% (27/32) showed excellent or good results.

Adult↗
PubMed1996

[Experimental research on the distribution of insulin in condyle during mandibular functional protrusion in growing rats].

The purpose of this study is to evaluate insulin change in condylar cartilage during functional advancement of rat mandible by immunohistochemical technique (ABC method) in order to provide further information about the role of insulin in orthopedics and the relationship between insulin and proliferation of condylar cartilage. Staining gradient of insulin is observed in condylar cartilage, with the stain deepest in the geriminal layer, medial in the transitional, least in the maturational layer. The posterior region of condylar cartilage in the experimental groups is shown to have thickened significantly as compared with the control groups, especially the germinal layer. Stained-positive cells exhibit deeper stain and higher percentage. The stain in the other layers is also more obvious than that in the control groups. The results suggest: Insulin level in condyle changes with the different cartilage layers. Insulin distribution appears higher when condylar chondrocytes proliferate rapidly and lower when they differentiate actively. Functional orthopedics may stimulate the growth of condylar cartilage and raise the insulin level. The demonstrates that insulin correlates with hyperplasia of conylar chondrocytes.

Animals↗
PubMed1996

[Research on the recombinant plasmid pDJH2 of L. interrogans serovar lai: sequencing and alignment with other known bacterial Omp sequence].

The Leptospira whole cell vaccine (LWCV) currently used in China is safe and effective, out the immunity following vaccination with two doses of the fluid medium vaccine is of low order. The duration of immunity conferred by this vaccine is rather short, six months or at most one year. Therefore, it is necessary to develop new generation vaccines against Leptospirosis for the developing world. In this paper we report the sequencing of the insert fragment of pDJH2 from genomic DNA of L. interrogans sevovar lai strain 017 and its alignment with other bacterial omp sequences. A genomic library of Leptospira interrogaans serovar lai strain 017 was constructed with the plasmid vector pUC18. A recombinant plasmid designated pJDH2 was screened from the genomic library. Inserted fragment of pDH2 is 1.9 kb by gel electrophoresis. Immunization/protection was studied in BALB/c mice model. The results showed highly significant difference between pDJH2 and pUC18 (control). Inserted fragment of pDJH2 DNA sequencing was performed by Dr Yan Zhengxin (Max-Planck-Institut for Biology. Tubingen, Germany). Insert fragment was cloned into pBluescript II KS-(stratagene) and sequenced by using AB1 (Applied Bio Systems, Model 373A). Two open reading frames of 565 and 662 nucleotides were identified. There were identifiable initiation codons, terminators, Shine-Dalgano ribosome combining site, Pribnow boxes and Sextama boxes within the 2 sequenced regions. Nucleotide sequences were analysed using Gene Work, a suit of computer program developed by Department of Biochemistry St. Jude Children's Research Hospital Memphis. U.S.A. The results of formatted alignment showed the predicted nucleotide sequence of ORF1 of the serovar lai had significant similarity with ORF2 (49.36%). L. kirschneri ompL1 (49.26%), Borrelia burgdoferi omp (48.97%), Treponema phagedenis omp (47.3%); Salmonella typhimurium ompC(46.87%), Yersinia enterocolitica ompH (46.7%), Leptospira borgpeterseni pfap (46.3%), and Serratia marcescens omp (43.3%). The close relationship of the pDJH2 ORF1 and ORF2 nucleotide sequences from Leptospira kirschneri ompL 1 is apparent. Whether the recombinant pDJH2 will prove useful for vaccine development remains to be tested.

Animals↗
PubMed1996

[Subclones of fragment DNA recombinant rpDJH2 of L. interrogans serovar lai strain 017 and it's expression of high level in E. coli].

Fragment of 1.9 kb recombinant DNA of pDJH2 was linked with vectors pT7-7 and pRSETs. Then they were transformed into E. coli JM109 (DE3) respectively. Expression of subclones was achieved in E. coli JM109 (DE3) with IPTG inducement. SDS-PAGE showed that the molecular weights of products were 68kd and 23 kd respectively. The amount of production seemed to be higher than that of the outer membrane proteins of L. interrogans serovar strain 017 in nature. Immunoblotting of pDJt and pDJrB2 (both are subclones) with the specific antiserum of anti-OMP of L. interrogans serovar lai strain 017 and the experiment of initiative immuno-protection in guinea pigs showed both protein-68 kd and 23 kd might be the antigens of immuno-protection on the outer membrane of L. interrogans serovar lai strain 017.

Animals↗
PubMed1996

[A preliminary study of the preventive and blocking effect of green tea grown in mengding mountain area on the esophageal cancer in rats].

Three groups (positive control or nitrosamine alone group, test group and control group) were included in this experiment. After the begining of the experiment, the rats of test group were given 2% green tea (common grade) solution by free drinking daily for 24 weeks. After 2 weeks of the begining of the experiment, the rats of the nitrosamine alone group and test group were injected with MANA, 5 mg/kg weekly for 20 weeks. The animals were sacrificed at 4 intervals. The incidence rates of esophageal cancer in the rats of the two groups sacrified at every interval were significantly different. The result suggested that green tea should have a preventive and blocking effect on the occurrence of esophageal cancer in rats.

Animals↗
PubMed1996

[The relationship between the retinal lipid peroxidation or antioxidation and age in rats].

OBJECTIVE: To investigate the relationship between the retinal lipid peroxidation (LPO) or antioxidation and age. METHODS: The thiobarbituric acid (TBA) and chemical luminescence methods, were used to detect the retinal malondialdehyde (MDA) content produced by LPO and superoxide dismutase (SOD) activity which represents the antioxidation ability of retina in 22 rats different ages. RESULTS: The retinal MDA contents were 0.18 +/- 0.06, 0.16 +/- 0.06, 0.38 +/- 0.11, 0.49 +/- 0.09 nmol/mg protein respectively in 5, 12, 18, 24 months old (F test, P < 0.01); the retinal SOD activities were 0.99 +/- 0.30, 2.48 +/- 0.56, 0.70 +/- 0.35, 0.85 +/- 0.57 U/mg protein respectively in 5, 12, 18, 24 months old rats (F test, P < 0.01). CONCLUSIONS: The retinal MDA content increased and SOD activity decreased with aging. The cumulative effects of the long-term photochemical damage and decreased antioxidation ability in retina might be the causes of the increased retinal LPO.

Aging↗
PubMed1996

Effects of Arg-Gly-Asp-Ser on Ca2+ transport of myocardial sarcoplasmic reticulum in rat septic shock.

AIM: To study the effects of Arg-Gly-Asp-Ser (RGDS), a synthetic short peptide of fibrinogen degradation, on the Ca2+ transport function of cardiac sarcoplasmic reticulum in rat septic shock. METHODS: RGDS 5 mumol.kg-1 was injected i.v. at 4 h and 14 h after cecal ligation and puncture (CLP) operation on rats. Highly purified membrane of sarcoplasmic reticulum (SR) was prepared from rat hearts. Assays were made of ATP-dependent Ca2+ uptake by cardiac SR and [3H] ryanodine binding to SR. RESULTS: The initial rate and the capacity of SR Ca2+ uptake were increased by 104% (P < 0.01) and 12% (P < 0.05), respectively, paralleled by an increase in Ca(2+)-ATPase activity and a decrease in calcium accumulation of myo- cardium of septic rats, whereas the Bmax and Kd values of Ca2+ activated [3H]ryanodine binding to SR were unaffected after RGDS administration. CONCLUSIONS: The results indicated that RGDS have cardioprotective effects of maintaining Ca2+ homeostasis of cardiac myocytes by enhancing SR Ca2+ uptake in rat septic shock.

Animals↗
PubMed1995

Discovery of a brain promoter from the human transferrin gene and its utilization for development of transgenic mice that express human apolipoprotein E alleles.

Transgenic mice carrying heterologous genes directed by a 670-bp segment of the regulatory sequence from the human transferrin (TF) gene demonstrated high expression in brain. Mice carrying the chimeric 0.67kbTF-CAT gene expressed TF-CAT in neurons and glial cells of the nucleus basalis, the cerebrum, corpus callosum, cerebellum, and hippocampus. In brains from two independent TF-CAT transgenic founder lines, copy number of TF-CAT mRNA exceeded the number of mRNA transcripts encoding either mouse endogenous transferrin or mouse endogenous amyloid precursor protein. In two transgenic founder lines, the chloramphenicol acetyltransferase (CAT) protein synthesized from the TF-CAT mRNA was estimated to be 0.10-0.15% of the total soluble proteins of the brain. High expression observed in brain indicates that the 0.67kbTF promoter is a promising director of brain expression of heterologous genes. Therefore, the promoter has been used to express the three common human apolipoprotein E (apoE) alleles in transgenic mouse brains. The apoE alleles have been implicated in the expression of Alzheimer disease, and the human apoE isoforms are reported to interact with different affinities to the brain beta-amyloid and tau protein in vitro. Results of this study demonstrate high expression and production of human apoE proteins in transgenic mouse brains. The model may be used to characterize the interaction of human apoE isoforms with other brain proteins and provide information helpful in designing therapeutic strategies for Alzheimer disease.

Alleles↗
PubMed1995

Multiple lineages of tumors express a common tumor antigen, P1A, but they are not cross-protected.

Whether tumors of different lineages share common Ags is a critical issue for understanding anti-tumor immune responses and for designing Ag-specific tumor immunotherapy. Because of lack of cross-protection among individually derived tumors, it has been proposed that tumor Ags are specific for individual tumors. Here we show that lack of cross-protection is not due to lack of a shared tumor Ag. Thus, a plasmocytoma J558 transfected with the costimulatory molecule B7 activates a cross-reactive CTL response in vivo. The major Ag recognized by the cross-reactive CTL is P1A, which is expressed in mastocytoma P815, plasmocytoma J558, and fibrosarcoma Meth A. Surprisingly, no significant cross-protection can be detected among P1A-expressing tumors after immunization with either P1A-expressing or B7-transfected P815 cells. Our results demonstrate that multiple lineages of tumors are not cross-protected even though they share a tumor Ag that can be recognized by CTL. These results have important implications for tumor immunotherapy.

Amino Acid Sequence↗
PubMed1995

Evidence for the covalent binding of SHAP, heavy chains of inter-alpha-trypsin inhibitor, to hyaluronan.

We previously showed that serum-derived 85-kDa proteins (SHAPs, serum-derived hyaluronan associated proteins) are firmly bound to hyaluronan (HA) synthesized by cultured fibroblasts. SHAPs were then identified to be the heavy chains of inter-alpha-trypsin inhibitor (ITI) (Huang, L., Yoneda, M., and Kimata, K. (1993) J. Biol. Chem. 268, 26725-26730). In this study, the SHAP.HA complex was isolated from pathological synovial fluid from human arthritis patients. The SHAP.HA complex was digested with thermolysin, followed by CsCl gradient centrifugation. The HA-containing fragments thus obtained were further digested with chondroitinase AC II and subjected to TSK gel high performance liquid chromatography (HPLC). Peptide-HA disaccharide-containing fractions (the SHAP.HA binding regions) were further purified by reverse phase HPLC. Major peaks were analyzed by protein sequencing and mass spectrometry (electrospray ionization mass spectrometry and collision induced dissociation-MS/MS). By comparison with the reported C-terminal sequences of the human ITI family, the peptides were found to correspond to tetrapeptides derived from the C termini of heavy chains 1 of and 2 of inter-alpha-trypsin inhibitor (HC1 and HC2), and heavy chain 3 of pre-alpha-trypsin inhibitor (HC3), respectively, and a heptapeptide from HC1. Mass spectrometric analyses suggested that the C-terminal Asp of each heavy chain was esterified to the C6-hydroxyl group of an internal N-acetylglucosamine of HA chain. This report is the first demonstration to give evidence for the covalent binding of proteins to HA.

Alpha-Globulins↗
PubMed1995

Distribution and activity of calcineurin in rat tissues. Evidence for post-transcriptional regulation of testis-specific calcineurin B.

Calcineurin (CN), a Ca2+/calmodulin-regulated phosphatase 2B, plays an important role in many biological processes including T-cell signal transduction. In the present study, the distribution and activity of CN were investigated in rat tissues. CN has a wide tissue distribution, as measured by enzyme-linked immunosorbent assay. CN concentrations are 0.2-0.6 micrograms/mg protein in most tissues, while the brain contains 3-10-fold higher concentrations. Immunohistochemical analyses using a monoclonal antibody to CN B subunit reveals that CN is not evenly distributed but concentrated in specific cells, especially in the brain, kidneys and testis. The specific enzymic activity of CN in tissues is around 10 pmol.min.mg protein-1, except in brain and liver (60 pmol.min-1.mg protein-1 compared to 3.6 pmol.min-1.mg protein-1). The immunosuppressants cyclosporin A and tacrolimus, but not rapamycin, inhibit the phosphatase activity of CN derived from most tissues tested, while CN activity from liver was resistant to cyclosporin A. Furthermore, transcripts and protein of the common CN B subunit and of the testis-specific form of CN B subunit were analyzed. The common CN B subunit transcripts and protein are detected in all tissues. Transcripts for the 'testis-specific' CN B subunit are also found in brain, lung, thymus and heart, while the protein is only detected in testis. This indicates that the testis-specific CN B subunit gene expression is regulated at both transcriptional and posttranscriptional levels. The findings demonstrate that CN is a widely distributed protein phosphatase and that its activity is regulated in a tissue-specific manner.

Amino Acid Sequence↗
PubMed1995

Mutational analysis and an alternatively spliced product of B7 defines its CD28/CTLA4-binding site on immunoglobulin C-like domain.

Costimulatory molecules B7 and B7-2 interact with T cell surface receptors CD28/CTLA4 and deliver a costimulatory signal essential for T cell growth. However, the structure basis of this interaction is not known. B7 and B7-2 are members of immunoglobulin (Ig) superfamily and their extracellular portion consists of an IgV- and IgC-like domain. Here we report that a naturally occurring, alternatively spliced form of B7 reveals that exon 3-encoded IgC domain is essential for CD28/CTLA4 binding. Mutational analysis of B7 demonstrates a critical role of several amino acids around loops between strands B and C and D and E, for binding CTLA4/CD28. These amino acids are clustered to form a single binding site centered at 201Y. A comparison of the effects of mutations on the binding of CD28 and CTLA4 reveals that CD28 and CTLA4 binds to the same site on B7. These results have important implications on the role of CTLA4 and CD28 in T cell costimulation. The structure of the CD28/CTLA4-binding site also provides valuable information for immune intervention targeted at the B7/B7-2-CD28/CTLA4 interactions.

Abatacept↗