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Biomedical subjects

H Zheng

Publications and source records attributed to H Zheng.

At least 253 records · Page 14Linked to original sources
PubMed1998

[A biomechanical evaluation of the effects of XW630 on the healing of experimental fracture].

The aim of this study was to evaluate whether tetracycline-estrone (XW630) plays a role in the healing of fracture. 120 rabbits were divided into 4 groups and subjected to osteotomies at the middle of both radials, and they were given XW630, estrone (E2), tetracycline (T) and 0.9% sodium chloride (C) respectively after operation by means of intramuscular injection (M) or local injection(L) in the fracture region. The biomechanical properties, including bending and compression, and the biochemical changes were tested at 30 days, 60 days and 90 days after osteotomy. The results showed that the bending stress and compression stress in the XW630(M) group were significantly higher than those in other groups at different periods after osteotomy. At 30 days after osteotomy, the bending ultimate stress in the XW630(M) group was 80% higher than that in group C, 76% higher than that in group E2, and 69% higher than that in group T. At 90 days after osteotomy, the bending ultimate stress in XW630(M) group increased to 80% of that of the normal radius, and it was 30% higher than that of group C, 34% higher than that of group E2 and 19.5% higher than that of group T. The biochemical changes corresponded with the changes biomechanical properties. These data suggest that XW630 given by intramuscular injection plays an obvious role in accelerating the healing of fracture. The medicine given by intramuscular injection is obviously more effective than that locally injected.

Animals↗
PubMed1998

[Study on the volatile oils of Murraya microphylla].

The essential oils from the leaves of Murraya microphylla (Merr. et Chun) Swing. growing in Sangya city, Hainan province have been studied by GC-MS and 22 compounds have been isolated and identified. Major compounds are identified as beta-terpinene (27.86%), decahdro-1, 1,7-trimethylene-1H-cyclopop[e] azulene (24.572%), 1,2,3,4,4 alpha, 5,6,8 alpha-octahydro-7-methyl-1-(1-methyl) naphthalene (11.426%), 3-carene (10.125%), 1, 1-dimethy1-2-(3-methyl-1, 3-butadienyl) cyclopropane (5.581%). According to Mr. Bipeixi's opinion, it exists two distinct sections within Murraya microphylla (Merr. et Chun) Swing. belongs to Murraya section Bergera. Monoterpene must be the dominated volatile fractions according Li Qian's opinion, but it is a exception. Maybe it has special taxonomic significance.

Chromatography, Gas↗
PubMed1998

[Retinal light damage: I. The influences of light intensity and exposure duration at moderate and low intensities of cyclic light].

PURPOSE: To study the influences of moderate- and low intensity of cyclic light exposure on the light damage of rat retina and its relationship with light intensity and exposure duration. METHODS: Twenty five 8-10 weeks old of female Sprague-Dawley rats were divided into 5 groups randomly. One group were as controls reared in dark-room, others were exposured to 12 hour light: 12 hour dark cyclic white xenon light from 3 to 28 days. The light intensities were 90-115 Lux(100 Lux), 400-650 Lux(500 Lux), 800-1,150 Lux(1,000 Lux), 1,400-1,650 Lux(1,500 Lux) separately. After various duration of exposure, the retina were evaluated with light microscopy, electron microscopy and morphometric study. RESULTS: Except for the intensity of 100Lux group, all of the other exposure intensities can induce the light damage of rat retina. The photoreceptor cells were affected most early. The higher of light intensity and the longer of exposure duration, the severer of the photoreceptor cell loss. In the severely damaged eye, RPE were also damaged. CONCLUSIONS: For the light damage of rat retina which is induced by moderate- or low intensity of cyclic light, the damage degree was both affected by light intensity and exposure duration.

Animals↗
PubMed1998

[Spectroscopic investigations on sol-gel transition of alginate solutions by addition of cupric ion].

Viscosity measurements and 13C-NMR, UV/VIS, and Raman spectroscopic studies have been carried out of various concentration of alginate solutions undergoing sol-gel transition induced by addition of cupric cation. From analyses of the spectra, a qualitative explaination was suggested of the interaction mode of the coordination between functional groups and cupric ions, the conformational change of polychains and the behaviour of solvent molecules druing the process of sol-gel transition. The mechanisms of phase transition of our system induced by the heavy metal ion have been discussed.

English Abstract↗
PubMed1998

[Molecular spectra study of fabrication reaction of lead styphnate].

The entire reaction process in the fabrication of lead styphnate in situ was analyzed by using laser Raman spectrometer and FTIR spectrometer, including reaction time determination, testing of the reactants proportions, and identification of the resultants in terms of molecular structure.

English Abstract↗
PubMed1997

The beta-amyloid precursor protein of Alzheimer's disease enhances neuron viability and modulates neuronal polarity.

beta-Amyloid precursor protein (betaPP) can reside at neuron and glial cell surfaces or undergo proteolytic processing into secreted fragments. Although betaPP has been studied extensively, its precise physiological role is unknown. A line of transgenic knock-out mice selectively deficient in betaPP survive and breed but exhibit motor dysfunction and brain gliosis, consistent with a physiological role for betaPP in neuron development. To elucidate these functions, we cultured hippocampal neurons from wild-type and betaPP-deficient mice and compared their ability to attach, survive, and develop neurites. We found that hippocampal neurons from betaPP-deficient mice had diminished viability and retarded neurite development. We also compared the effects of betaPP secretory products, released from wild-type astrocytes, on process outgrowth from wild-type and betaPP-deficient hippocampal neurons. Outgrowth was enhanced at 1 d in the presence of wild-type astrocytes, as compared with betaPP-deficient astrocytes. However, by 3 d, neurons had shorter axons but more minor processes with more branching when cocultured with wild-type astrocytes, as compared with betaPP-deficient astrocytes. Our data demonstrate that cell-associated neuronal betaPP contributes to neuron viability, axonogenesis, and arborization and that betaPP secretory products modulate axon growth, dendrite branching, and dendrite numbers.

Alzheimer Disease↗
PubMed1997

Persistent systemic production of human factor IX in mice by skeletal myoblast-mediated gene transfer: feasibility of repeat application to obtain therapeutic levels.

Myoblast-mediated gene transfer and its repeated applications were tested for achieving a long-term stable systemic production of human factor IX (hFIX) at a therapeutic level in SCID mice. Primary skeletal myoblasts were stably transfected with a hFIX expression plasmid vector, pdLMe4 betaA-hIXm1, which contains a hFIX minigene under the control of a beta-actin promoter with muscle creatine kinase enhancers. Myotubes derived from the myoblasts produced 1,750 ng hFIX/10(6) cells/24 hours in culture. hFIX secretion by the myoblasts and thereof derived myotubes were equally efficient, and myotubes were shown to have a sufficient secretory capacity to handle a substantially elevated production of hFIX. After intramuscular injection of 5, 10, and 20 x 10(6) myoblasts, SCID mice stably produced hFIX into the systemic circulation proportional to the number of implanted cells, and the expression levels were maintained for at least up to 10 months (end of the experiment). Additional cell injections administered to animals that originally received 10 x 10(6) cells approximately 2 months later elevated the systemic hFIX levels to an average of 182 +/- 21 ng/mL, a therapeutic level, which persisted for at least 8 months (end of the experiment). These results indicate that long-term, stable systemic production of hFIX at therapeutic levels can be achieved by repeated application of myoblast-mediated gene transfer.

Animals↗
PubMed1997

Presenilin 1 is required for Notch1 and DII1 expression in the paraxial mesoderm.

Approximately 10% of cases of Alzheimer's disease are familial and associated with autosomal dominant inheritance of mutations in genes encoding the amyloid precursor protein, presenilin 1 (PS1) and presenilin 2 (PS2). Mutations in PS1 are linked to about 25% of cases of early-onset familial Alzheimer's disease. PS1, which is endoproteolytically processed in vivo, is a multipass transmembrane protein and is a functional homologue of SEL-12, a Caenorhabditis elegans protein that facilitates signalling mediated by the Notch/LIN-12 family of receptors. To examine potential roles for PS1 in facilitating Notch-mediated signalling during mammalian embryogenesis, we generated mice with targeted disruptions of PS1 alleles (PS1-/- mice). PS1-/- embryos exhibited abnormal patterning of the axial skeleton and spinal ganglia, phenotypes traced to defects in somite segmentation and differentiation. Moreover, expression of mRNA encoding Notch1 and Dll1 (delta-like gene 1), a vertebrate Notch ligand, is markedly reduced in the presomitic mesoderm of PS1-/- embryos compared to controls. Hence, PS1 is required for the spatiotemporal expression of Notch1 and Dll1, which are essential for somite segmentation and maintenance of somite borders.

Animals↗
PubMed1997

In vitro and in vivo resistance to cisplatin in cells that have lost DNA mismatch repair.

In vitro studies have shown that loss of DNA mismatch repair due to lack of either hMSH2 or hMLH1 activity results in low-level resistance to cisplatin but not to oxaliplatin, an analogue that produces a different type of DNA adduct. No information is currently available on whether this low-level resistance is sufficient to result in enrichment of mismatch repair-deficient cells during drug exposure in vitro or to account for clinical failure of treatment in vivo. Mixed populations of cells containing a minority of DNA mismatch repair-deficient cells constitutively expressing green fluorescence protein were exposed repeatedly in vitro to cisplatin and oxaliplatin. Treatment with cisplatin resulted in a gradual enrichment for DNA mismatch repair-deficient cells, whereas treatment with oxaliplatin did not. MSH2-/- and MSH2+/+ embryonic stem cells were established as xenografts in athymic nude mice. Animals were treated 48 h after tumor implantation with a single LD10 dose of either cisplatin or oxaliplatin. MSH2-/- tumors were significantly less responsive to cisplatin than MSH2+/+ tumors, whereas there was no difference in sensitivity to oxaliplatin. These results demonstrate that the degree of cisplatin resistance conferred by loss of DNA mismatch repair is sufficient to produce both enrichment of mismatch repair-deficient cells during treatment in vitro and a large difference in clinical responsiveness in vivo. The results identify loss of DNA mismatch repair as a mechanism of resistance to cisplatin but not oxaliplatin.

Adenocarcinoma↗
PubMed1997

Conserved mutations in human ferritin H pseudogenes: a second functional sequence or an evolutionary quirk?

This paper describes a search for a second functional human ferritin H gene in a collection of genomic clones. Nine new H-like sequences have been mapped to chromosomes 1p22-31, 1q32-42, 2q32-33, 3q21-23, 13q12, 14, 17p11-pter and X. These were examined for evidence of possible functionality by sequencing and by searching for possible introns. All except an uncharacterized sequence on chromosome 13 appear to be processed pseudogenes. However, nearly all share several conserved differences with the known functional sequence. These differences occur at regions of unusual structure. It is not known whether these sequences are derived from a second functional gene or from site-specific mutations in the generation of pseudogenes from the known functional gene. We also show that several hominoids contain H gene families with similar complexities to humans and that most of the human genes have counterparts in chimpanzees and gorillas.

Animals↗
PubMed1997

Development of a Rhodococcus equi-Escherichia coli plasmid shuttle vector.

Isolates of Rhodococcus equi from pneumonic foals possess an 85- or 90-kb virulence-associated plasmid. A prominent, thermoregulated surface antigen, VapA, encoded by these plasmids is thought to be important in virulence. A 135-kb fragment containing the origin of replication of R. equi strain 103 virulence-associated plasmid (pOTS) was identified, sequenced, and its location identified. A simple R. equi-Escherichia coli shuttle plasmid (pRE-1) derived from the E. coli plasmid pACYC177 and the pOTS ori was developed. The plasmid transformed readily and was stable in either host and expressed kanamycin resistance but not beta-lactamase in R. equi. An improved 5.9-kb vector, pRE-7, was developed from pRE-1 and pBluescript. Subcloning of vapA into the multiple cloning site of the beta-galactosidase gene of pRE-7 resulted in weak expression of the gene both in E. coli and R. equi. The shuttle vector may be useful in examining regulation of virulence gene expression in R. equi.

Bacterial Proteins↗
PubMed1997

Molecular characterization and ultrastructural localization of Plasmodium falciparum Hsp 60.

Heat shock proteins (Hsp) are a group of highly conserved proteins which are widely represented phylogenetically. Genes for members of the Hsp 70, 90 and 60 families have been cloned from the human malaria parasite Plasmodium falciparum. In this study, we have cloned and expressed the P. falciparum Hsp 60 (PfHsp60) in E. coli. The sequence analysis identified a previously unknown intron of 257 bp beginning after the nucleotide 142 in the coding sequence. Antisera raised against the recombinant PfHsp60 was employed in immunoprecipitation studies with biosynthetically labeled parasite extracts to investigate regulation of expression of PfHsp60 at various temperatures. In contrast to the three to four fold accumulation of PfHsp60 transcripts in heat shocked parasites (37-40 degrees C), the expression of PfHsp60 was not induced in the blood stages of P. falciparum. On the other hand, the effect of heat induction on PfHsp70 was seen both at the level of specific mRNA and protein. In these studies we also observed co-immunoprecipitation of a number of other cellular proteins suggesting possible interaction with PfHsp60. Immunofluorescence analysis indicated the presence of PfHsp60 in the cytoplasm of all the various stages of the parasite. In addition, immunoelectron microscopic analysis distinctly localized PfHsp60 in the mitochondrion of P. falciparum. This study suggests that different mechanisms are involved in the regulation of expression of various members of the heat shock proteins in the parasite.

Animals↗
PubMed1997

Expression of the DNA mismatch repair proteins hMLH1 and hPMS2 in normal human tissues.

hMLH1 and hPMS2 are part of the DNA mismatch repair complex. Mutations in these genes have been linked to hereditary non-polyposis colon cancer; they also occur in a variety of sporadic cancers. Western blot analysis and immunohistochemistry demonstrated that hMLH1 and hPMS2 are widely expressed nuclear proteins with a distribution pattern very similar to that previously described for hMSH2. These observations showing similar localization of hMLH1 and hPMS2 with hMSH2 are consistent with the biochemical function of these proteins in DNA mismatch repair.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Influence of oxygen on radiation-induced DNA damage in testicular cells of C3H mice.

Radiation-induced DNA single-strand break (ssb) induction and rejoining were measured in murine testicular cells using the alkaline comet assay. Individual cells in different stages of differentiation were identified on the basis of DNA content. As expected, induction of DNA ssb in testis cells irradiated on ice was independent of ploidy, and the extent of damage was similar to that produced in cells from other normal tissues. However, in vivo irradiation of air-breathing mice produced more ssb in haploid than tetraploid germ cells, although their rates of rejoining were similar and comparable to repair rates of cells from other normal tissues. In addition, irradiation of testis in situ produced only half as much damage as irradiation in vitro, and this could be explained only in part by the rapid ssb rejoining occurring during irradiation and cell isolation. A lower cellular oxygenation was postulated to account for the apparent resistance of testis cells to induction of breaks and the difference in induction in relation to DNA content. This was confirmed when carbogen inhalation and treatment with nicotinamide not only increased the overall degree of ssb induction in all these cells, but also reduced differences between cells of different ploidies. Results using the hypoxic cell cytotoxin RSU 1069 confirmed that the extent of hypoxia was not as severe in the testis as in the SCCVII murine tumour. It can be concluded from these data that the oxygenation of all testis cells is low enough to confer radioresistance, and that haploid testis cells are less hypoxic than tetraploid spermatocytes.

Animals↗
PubMed1997

Epstein-Barr virus-infected lymphocytes in non-neoplastic lymph nodes of patients infected with human immunodeficiency virus.

Non-Hodgkin's lymphomas occurring in AIDS patients (AIDS-NHL) are known to be highly associated with Epstein-Barr virus (EBV). However, there have been no previous detailed studies of the distribution of EBV-infected non-neoplastic lymphoblasts, which may act as precursors of AIDS-NHL. In the present study, an attempt was made to detect such EBV-infected cells in patients' lymphoid organs. Fifteen non-neoplastic lymph nodes obtained from HIV-positive individuals were processed for in situ demonstration of EBV-encoded small RNA (EBER-1) and EBV-encoded latent membrane protein 1 (LMP-1). An increased number of EBER-1-expressing cells were observed (9/15). EBER-1-positive cells were present much more frequently in advanced cases, as evaluated using the histopathologic criteria of Grundmann (1/6 cases showing irregular follicular hyperplasia; 3/4 showing the beginning follicular destruction; 2/2 showing progressive follicular destruction; 3/3 showing follicular involution). LMP-1 was detected in 3/9 EBER-1-positive cases, and all three of these cases were at the most advanced stage. Furthermore, cells expressing LMP-1 were larger (62.83 +/- 6 microm2) than EBER-1+ LMP-1- cells (29.05 +/- 7 microm2). These results indicate that cells with latent expression of the EBV gene increase in number in lymphoid organs of HIV-infected individuals at an advanced stage and that some of the cells are in a transformed state. It is possible to speculate that these cells are precursors of AIDS-NHL.

Cell Count↗
PubMed1997

Limited excitatory local effector function of gastric vagal afferent intraganglionic terminals in rats.

Intraganglionic laminar endings (IGLEs) are complex terminal structures of vagal afferent origin, distributed throughout the myenteric plexus of the esophagus and gastrointestinal tract and without a known function. They may serve local effector function by means of peripheral axon reflexes, analogously to dorsal root afferents. To test this possibility, vagal afferent fibers were antidromically activated by suprathreshold electrical stimulation of the cervical vagus nerve in anesthetized rats that underwent prior supranodose vagotomy, and responses of myenteric neurons were monitored with Fos immunocytochemistry. Stimulation of vagal afferents produced Fos expression in a slightly, but significantly, higher proportion of myenteric plexus neurons of the gastric corpus (1.02 +/- 0.21%, P < 0.05) and esophagus (1.59 +/- 0.46%, P < 0.05) than in control animals with sham-stimulation (corpus, 0.12 +/- 0.05%; esophagus, 0.18 +/- 0.18%). Stimulation of vagal efferents produced widespread Fos induction in myenteric neurons. Given the many enteric neurons in close anatomic contact with IGLEs and the low proportion of Fos activated neurons after selective afferent stimulation, the results do not support a widespread excitatory local effector function of IGLEs. However, inhibitory effects and/or weak excitatory synaptic inputs that do not engage Fos expression cannot be ruled out.

Analysis of Variance↗