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Biomedical subjects

H Zhu

Publications and source records attributed to H Zhu.

At least 487 records · Page 27Linked to original sources
PubMed1994

[Hair cell regeneration and recovery following gentamicin induced damage in the chick cochlea].

Two-day old chicks were given gentamicin (GM) and kanamycin (KM) for 10 days and then the cochleas were processed for both scanning electron microscopy and light microscopy on the same day and in 1, 2, 3, and 4 weeks following the last injection to examine hair cells regeneration and recovery. The result showed that hair cell loss was up to 40% in the base of the basilar papilla following GM and KM administration. One week after injection, however, most of the damaged region was replaced with regenerated hair cells. Three to four weeks later, the regenerated hair cells were developed into normal sensory hair cells. This experiment demonstrated that the hair cells in the chick cochlea were able to regenerate and recover following GM and KM induced damage.

Animals↗
PubMed1994

[Synchronous analysis of multi-channel spectrum for human resonance cavity].

The synchronous analysis of multichannel spectrum were used to determine the regulars, conditions and characters of the resonance when subjects pronounced. 140 subjects were selected for test and 1040 pieces of sound sample were collected, then the analysis of different parts (mouth, throat, head and chest) was done. The results of the analysis of variance showed that there was much difference among the various professional workers, different places of articulation, and patients with voice disorders in spectrum analysis (P < 0.001). Each part of resonance frequencies was put forward of pronouncing system. High frequency resonance comes from head and pharynx (above 2000 Hz high resonance cavity), and low frequency resonance comes from chest and larynx (less than 2000 Hz resonance cavity). We suggest that there are six degrees of clinical objective classification of the pathologic hoarseness.

Female↗
PubMed1994

[Glutamate receptor and GABA receptor expressed in amphibian oocytes after injection of chicken retina mRNA].

The glutamate receptor and GABA receptor of chicken retina were studied with the expression system of amphibian oocyte. Some important results were obtained: L-glutamate, kainate, AMPA and quisqualate could all induce rapid and smooth depolarizing currents in oocytes. NMDA, L-AP4, trans-ACPD and L-aspartate had no effects. The antagonism of kainate response by AMPA and quisqualate was found, and it seemed that AMPA, quisqualate and KA could act on the same receptor. Comparing the responses to L-Glu and NMDA, it was found that the mRNA abundance of metabotropic glutamate receptor and NMDA receptor in chicken retina was much lower than that of chicken brain. The GABA receptor in chicken retina was very different from that of bovine retina. And although about 10% of the GABA response was insensitive to bicuculline, but most GABA receptors in chicken retina were proved as GABAA receptors.

Animals↗
PubMed1994

[Studies on glycine receptor, acetylcholine receptor and ion channels expressed in amphibian oocytes after injection of chicken retina mRNA].

Glycine receptor, acetylcholine receptor and voltage dependent ion channels expressed in amphibian oocytes after injection of chicken retinal mRNA were studied by using voltage clamp technique. The current response to glycine was proved as small, and the acetylcholine receptor was identified as N type. Aspartate, serotonin and dopamine induced no responses. In addition, voltage dependent ion channels were detected, and were identified as delayed rectifier potassium channel and sodium channel.

Animals↗
PubMed1994

[Immunological detection of organophosphate resistance of Culex mosquitoes using anti-esterase monoclonal antibody].

Different strains of Culex mosquitoes (Cx. pipiens quinquefasciatus and Cx. Pipiens pallens) were immunologically-detected for organophosphate resistance with anti-esterase monoclonal antibody, and the results were compared with those detected by bioassay and biochemical microplate assay. It was found that the resistance-detection-rate detected by immunologic methods were higher than the corresponding data detected by the biochemical method, and the levels of resistance detected by sandwich-ELISA were higher than the corresponding levels detected by bioassay and the biochemical method. The thresholds for resistance in sandwich-ELISA were (at absorbence 450) > or = 0.5, and in microplate assay were (at absorbence 590) > or = 2.5 x 10(-3) mumol/min.mg protein. Dot-ELISA method was developed to meet the requirement of the field test and proved to be fast and convenient, especially in the detection of samples with higher esterase activity.

Animals↗
PubMed1994

[Synthesis of new fluorescent reagent and its application in solution fluorescence analysis].

In our laboratory we have designed and synthesized a new fluorescent CGE(N), which has a fluo-rigen and can react with active hydrogen in chemical compounds. We have studied its application in solution fluorescence, thin-layer fluorescence and solid fluorescence analysis. The results have indicated that CGE (N) is a good reagent in analysis. And the example of its application in solution fluorescence analysis is given in this paper.

Colchicine↗
PubMed1994

Aplysia cell adhesion molecules and serotonin regulate sensory cell-motor cell interactions during early stages of synapse formation in vitro.

Long-term facilitation of sensorimotor synapses of Aplysia in culture by serotonin (5-HT) is accompanied by two changes: an increase in the number of sensory cell branches and varicosities contacting the major axons of the target motor cell L7, and a downregulation of Aplysia cell adhesion molecules (apCAM) from the surface of the presynaptic sensory cell. We tested the hypothesis that the two changes may be linked; the 5-HT-induced decrease of apCAM levels from sensory neurites may defasciculate sensory neurites from each other and make the surface of the motor axons a more attractive substrate for new growth and synapses. We used developing cultures to examine the relationship of neuritic branching, varicosity formation, and efficacy of the connections formed by sensory cells to levels of apCAM expression on the motor cell. We then determined the consequences of 5-HT applied during the early period of interaction between sensory and motor cells (day 1 or 2 in culture) on the pattern of sensory cell growth and synapse formation. We report that the number of sensory cell branches and varicosities, and the ability of sensory growth cones to fasciculate with L7 axons and form chemical connections correlate with the level of apCAM expression on different regions of L7. Early exposure to 5-HT increased the number of sensory cell branches and varicosities contacting newly regenerated distal neurites of L7 to levels that would normally occur when the sensory neurites interact with the major proximal axons of L7. Treatment with 5-HT also modulated the efficacy of the developing synaptic connections. The change in synapse efficacy was accompanied by an increase in the formation of new sensory varicosities and branches with pioneering growth cones extending on the major axons of L7. The results are consistent with the hypothesis that treatment with 5-HT modulates local differences in the expression of cell adhesion molecules on the surface of the interacting cells making motor neurites more attractive for sensory growth cones, thereby affecting new sensory neuritic growth and synapse formation.

Animals↗
PubMed1994

Receptor chimeras indicate that the met tyrosine kinase mediates the motility and morphogenic responses of hepatocyte growth/scatter factor.

The met protooncogene is a receptor tyrosine kinase for hepatocyte growth factor/scatter factor (HGF/SF). HGF/SF is a multifunctional cytokine secreted mainly by mesenchymal cells that stimulates movement, invasion, and morphogenesis of some epithelial and endothelial cells and mitogenicity of others. Although the met receptor tyrosine kinase is a high affinity receptor for HGF/SF, it is not known whether this receptor can mediate the pleiotropic functions of HGF/SF. To investigate this in epithelial cells that normally respond to HGF/SF, we generated a chimeric receptor containing the extracellular domain from the colony stimulating factor 1 (CSF-1) receptor fused to the transmembrane and cytoplasmic domain of the met receptor. We show that the CSF-MET chimera, when expressed in Madin-Darby canine kidney (MDCK) epithelial cells, is fully functional. Treatment of MDCK cells expressing the chimera with CSF-1 leads to cell dissociation and scattering, as well as invasion and tubule formation of cells grown in collagen matrices. This effect is dependent on a functional met kinase. Stimulation of the receptor chimera with CSF-1 leads to activation of the met kinase and tyrosine phosphorylation of the chimeras in vivo, whereas a kinase inactive mutant chimera shows no biological response to CSF-1. These findings demonstrate that stimulation of the met kinase is sufficient and essential to mediate the motogenic, invasive, and morphogenic responses of MDCK cells to HGF/SF and that this is a suitable system for a detailed analysis of the molecular signaling events involved in these responses.

Amino Acid Sequence↗
PubMed1993

The hemoglobins of the bullfrog, Rana catesbeiana. The cDNA-derived amino acid sequences of the alpha chains of adult hemoglobins B and C: their roles in deoxygenation-induced aggregation.

The adult bullfrog (Rana catesbeiana) has two major tetrameric hemoglobins, B and C, which share a common beta chain but have different alpha chains. Components B and C associate upon deoxygenation to form a complex of the form BC2, a trimer of tetramers that depends on contacts between the alpha B and alpha C chains. Nucleotide sequences of cDNA transcripts for these chains have been determined. Transcripts were identified by analysis of the amino acid compositions of the tryptic peptides of the components and by partial amino acid sequencing. These results, together with the amino acid sequence of the beta chain (Tam, L.-T., Gray, G. P., and Riggs, A. F. (1986) J. Biol. Chem. 261, 8290-8294), permit an analysis of the structures of the alpha 2 beta 2 tetramers of hemoglobins B and C. Molecular modeling suggests possible residues at the alpha B-alpha C interfaces in the BC2 trimer and additional alpha C-alpha C contacts that would form a closed ring of six alpha chain subunits that would further stabilize the BC2 trimer. Phylogenetic analysis of the alpha B sequence suggests that it may be a "tadpole" chain, the temporal expression of which has shifted from larva to adult.

Amino Acid Sequence↗
PubMed1993

Induction of apoptosis in fibroblasts by IL-1 beta-converting enzyme, a mammalian homolog of the C. elegans cell death gene ced-3.

The mammalian interleukin-1 beta-converting enzyme (ICE) has sequence similarity to the C. elegans cell death gene ced-3. We show here that overexpression of the murine ICE (mICE) gene or of the C. elegans ced-3 gene causes Rat-1 cells to undergo programmed cell death. Point mutations in a region homologous between mICE and CED-3 eliminate the ability of mICE and ced-3 to cause cell death. The cell death caused by mICE can be suppressed by overexpression of the crmA gene, a specific inhibitor of ICE, as well as by bcl-2, a mammalian oncogene that can act to prevent programmed cell death. Our results suggest that ICE may function during mammalian development to cause programmed cell death.

Animals↗
PubMed1993

The extracellular hemoglobin of the earthworm, Lumbricus terrestris. Determination of subunit stoichiometry.

The giant extracellular hemoglobin of the earthworm, Lumbricus terrestris, has four major O2-binding chains, a, b, and c (forming a disulfide-linked trimer) and d ("monomer"). Participation of additional "linker" chains L1, L2, and L3 is necessary for the assembly of the approximately 3,900+ kDa two-tiered hexagonal structure. We have determined the proportions of linker chains, trimer, and chain d in the hemoglobin by reverse phase high performance liquid chromatography which resolves all of the components and also permits simultaneous determination of the heme content. The proportions of components were determined by two independent procedures: integration of the absorbance peaks at 220 nm and amino acid analysis of the peak fractions. The results indicate that the weight proportion of linker chains is 0.163 +/- 0.023. This value, together with molecular masses determined both by amino acid sequence analysis and by matrix-assisted laser desorption mass spectrometry, gives a molar ratio of abcd chains to linkers of 8:1, corresponding to the minimal unit (abcd)2.L. This ratio suggests that 24 (abcd)2 units and 24 linker chains form the complete structure with a total calculated mass of polypeptide of 3,975 kDa with hemes on chains a, b, c and d and on one linker. The calculated heme content is 3.1% not including carbohydrate. This accounts for a measured heme content of 3.0% on a polypeptide basis. Additional mass (approximately 133 kDa, 3.4%), attributed to carbohydrate, brings the total mass to 4,108 kDa with a minimum molecular mass/heme of 20,500 Da. The presence of equimolar quantities of three unique linker chains means that the apparent one-twelfth structural units seen by electron microscopy cannot all be identical.

Amino Acid Sequence↗
PubMed1993

Sensate and insensate in-shoe plantar pressures.

In the individual with loss of protective sensation, the presence of high plantar pressures has been considered a risk factor for the development of plantar ulceration. Previous studies of insensate plantar pressures have measured a limited number of isolated, barefoot steps in a laboratory setting. Such isolated snapshots of barefoot plantar pressures do not give us insight into possible step-to-step variations or what plantar pressures occur when wearing shoes. The purpose of this study was to quantitatively examine and compare in-shoe plantar pressures during continuous walking by normal sensate and diabetic insensate subjects. A portable, insole data-acquisition system was used for pressure measurement during 4 minutes of normal continuous walking. Seven pressure sensors were placed in each insole under posterior and anterior heels, the metatarsal heads, and hallux. Twelve sensate and five insensate subjects were studied. We found that the insensate group had higher plantar pressures under posterior and anterior heels and the first metatarsals compared with the sensate group. From the study of the coefficients of variation, we demonstrated a larger step-to-step variation in plantar pressures for the insensate during continuous walking, suggesting the need for caution in interpreting the data from isolated force plate steps when studying insensate individuals.

Adult↗
PubMed1993

Beta-COP is essential for transport of protein from the endoplasmic reticulum to the Golgi in vitro.

Using a novel in vitro assay which allows us to distinguish vesicle budding from subsequent targeting and fusion steps, we provide the first biological evidence that beta-COP, a component of non-clathrin-coated vesicles believed to mediate intraGolgi transport, is essential for transport of protein from the ER to the cis-Golgi compartment. Incubation in the presence of beta-COP specific antibodies and F(ab) fragments prevents the exit of vesicular stomatitis virus glycoprotein (VSV-G) from the ER. These results demonstrate that beta-COP is required for the assembly of coat complexes mediating vesicle budding. Fractionation of rat liver cytosol revealed that a major biologically active form of beta-COP was found in a high molecular pool (> 1,000 kD) distinct from coatomer and which promoted efficient vesicle budding from the ER. Surprisingly, rab1B could be quantitatively coprecipitated with this beta-COP containing complex and was also essential for function. We suggest that beta-COP functions in an early step during vesicle formation and that rab1B may be recruited as a component of a precoat complex which participates in the export of protein from the ER via vesicular carriers.

Animals↗
PubMed1993

Cooperative DNA binding of p53 with TFIID (TBP): a possible mechanism for transcriptional activation.

The p53 tumor-suppressor gene product, a sequence-specific DNA-binding protein, has been shown to act both as a transcriptional activator and repressor in vivo and in vitro. Consistent with its roles in regulating transcription are recent observations that p53 binds directly to the TATA box-binding protein (TBP) subunit of the basal transcription factor TFIID. Here, we show that p53 cooperates with either recombinant TBP or partially purified TFIID in binding to a DNA fragment containing both a specific p53-binding site (RGC) and a TATA box (RGC-TATA). Surprisingly, both TBP and TFIID also stimulate p53 binding to DNA containing a specific p53-binding site but lacking a TATA box. These data are supported by the observation that p53 and Drosophila TBP combinatorily activate transcription in vivo. Our results suggest that p53 activates transcription through the formation of a more stable p53-TFIID-promoter complex. We also examined whether p53 might affect the ability of TBP or TFIID to interact with DNA containing a TATA box but lacking a p53-binding site. Although p53 strongly inhibited the interaction of TBP with such DNA, it had virtually no effect on TFIID binding. Thus, transcriptional repression by p53 may require additional functions other than inhibiting TBP binding.

Base Sequence↗
PubMed1993

The xynC gene from Fibrobacter succinogenes S85 codes for a xylanase with two similar catalytic domains.

The xynC gene of Fibrobacter succinogenes S85 codes for a 66.4-kDa xylanase which consists of three distinct domains separated by two flexible regions rich in serine residues. Domains A and B of XynC code for catalytic domains with 56.5% identity and 9.6% similarity with each other, and both domains share homology with xylanases of Ruminococcus flavefaciens, Neocallimastix patriciarum, Clostridium acetobutylicum, Bacillus pumilus, Bacillus subtilis, and Bacillus circulans. More than 88% of the xylanase activity of Escherichia coli cells carrying the original 13-kb recombinant plasmid was released from intact cells by cold water washes. The major products of hydrolysis of xylan by both domains were xylose and xylobiose, indicating that the xynC gene product exhibits catalytic properties similar to those of the XynA xylanases from R. flavefaciens and N. patriciarum. So far, these features are not shared broadly with bacteria from other environments and may indicate specific selection for this domain structure in the highly competitive environment of the rumen.

Amino Acid Sequence↗
PubMed1993

A novel, tissue-restricted zinc finger protein (HF-1b) binds to the cardiac regulatory element (HF-1b/MEF-2) in the rat myosin light-chain 2 gene.

The AT-rich element MEF-2 plays an important role in the maintenance of the muscle-specific expression of a number of cardiac and skeletal muscle genes. In the MLC-2 gene, an AT-rich element (HF-1b) which contains a consensus MEF-2 site is required for cardiac tissue-specific expression. The present study reports the isolation and characterization of a cDNA which encodes a novel C2H2 zinc finger (HF-1b) that binds in a sequence-specific manner to the HF-1b/MEF-2 site in the MLC-2 promoter. A number of independent criteria suggest that this HF-1b zinc finger protein is a component of the endogenous HF-1b/MEF-2 binding activity in cardiac muscle cells and that it can serve as a transcriptional activator of the MLC-2 promoter in transient assays. These studies suggest that, in addition to the previously reported RSRF proteins, structurally divergent transcriptional factors can bind to MEF-2-like sites in muscle promoters. These results underscore the complexity of the regulation of the muscle gene program via these AT-rich elements in cardiac and skeletal muscle.

Amino Acid Sequence↗
PubMed1993

Study of occupational lung cancer in asbestos factories in China.

A retrospective cohort study (1972-81) of occupational cancers in asbestos (chrysotile) factories has been previously published. In this paper the results of continued tracing and interviewing of members of this cohort from 1982 to 1986 is reported. The cohort included 5893 persons (45,974 person-years for men and 39,445 person-years for women). Malignant tumours played a large part in causes of death (36.9%). There were 183 cancers and 67 lung cancers among 496 deaths. The mortality due to lung cancer had a tendency to increase. By comparison with a control group, the RR of lung cancer was 5.32 (p < 0.01), and the SRR of lung cancer was 4.2 (p < 0.01), significantly higher than those of a control group. Among 148 cases of death from asbestosis there were 33 cases complicated with lung cancer (22.3%). The dose-response relations between exposure to asbestos and incidence of asbestosis and lung cancer were also studied in one asbestos factory. There was a positive correlation. A synergistic effect was found between cigarette smoking and lung cancer. Preventive and control measures and exposure limits for asbestos dust in the air of workplaces were recommended.

Asbestos, Serpentine↗