Search PubMed⌕ Search

Biomedical subjects

Z He

Publications and source records attributed to Z He.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Human cytomegalovirus inhibits the proliferation of CFU-MK in vitro].

OBJECTIVE: To investigate the effect of human cytomegalovirus (HCMV) on the proliferation of colony forming unit-megakaryocyte (CFU-MK). METHODS: Semi-solid CFU-MK culture system was used to observe the effect of HCMV AD169 strain on CFU-MK growth of 20 cord blood samples. HCMV DNA and immediate early antigen (IEA) mRNA in CFU-MK were detected by in situ-polymerase chain reaction (IS-PCR) and reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: HCMV AD169 suppressed the differentiation and proliferation of CFU-MK in vitro significantly. The suppression was in a dose-dependent fashion. HCMV DNA was successfully detected in colony cells from viral infection group, and did the expression of HCMV IEA mRNA. CONCLUSION: HCMV AD169 can directly infect megakaryocyte progenitor and suppress their proliferation and differentiation.

Cell Proliferation↗
PubMed2001

[A study of the acting mechanism of aspirin for resistance to oxidative damage].

OBJECTIVE: To explore the mechanism of aspirin for resistance to oxidative damage in endothelial cells. METHODS: Using cultured endothelial cells, we measured the levels of aspirin induced ferritin expression on resistance to hydrogen peroxide toxicity toward cells in the presence of the iron chelator desferrioxamine added to FeCl3. RESULTS: Aspirin at low concentration (0.1 mmol/L) induced significant increase of ferritin expression in a time- and concentration-dependent fashion up to 25% over basal levels(P < 0.05). Preincubating the cells for 8 h with aspirin (0.1 mmol/L) reduced lactate dehydrogenase(LDH) release rate by 50%, toxicity reduction by 40%, and significant decrease of malondialdehyde (MDA) production. Aspirin induced cytoprotection from H2O2 damage was also in a concentration- and time-dependent fashion. However, in the presence of the iron chelator desferrioxamine, aspirin enhanced ferritin synthesis was abrogated, in contrast, FeCl3 increased aspirin induced ferritin synthesis in cells. CONCLUSION: The study suggested that the antioxidation of aspirin was brought into action by affecting the cellular iron metabolism pathway to induce ferritin synthesis.

Antioxidants↗
PubMed2001

[An experimental study on effects of pingyangmycin on vessels].

OBJECTIVE: The aim of this study was to investigate the mechanism of Pingyangmycin sclerotherapy for cavernous hemangiomas. METHODS: Totally 9 rabbits (one as the control) were selected to be injected with Pingyangmycin and sodium morrhuate into the auricularis posterior vein, and then these veins were examined histologically 2, 7, 14 and 21 days after injection respectively. RESULTS: After injection, Pingyangmycin nonspecifically made the endothelia and veins defective, and induced proliferation of endothelial cells and smooth muscle cells after 7 days. Further, the veins became sclerostenosis 21 days after injection. On the other hand, sodium morrhuate caused thrombosis quickly and the vascular cavity disappeared. Finally, the thrombus became fibrogenesis. The local skin could be observed swollen and necrosis. CONCLUSION: Pingyangmycin is a better sclerosant for the therapy of cavernous hemangioma.

Animals↗
PubMed2001

[Study on reclassification of extremely thermoacidophilic archaea strain S5].

The further study on thermoacidophilic archaea strain S5, with has been identified as Sulfosphaerellus thermoacidophilum gen.nov.,sp.nov, has shown it was able to grow facultatively aerobically by means of two sulfur-metabolizing modes of chemolithotrophy which is the characteristic of Acidianus. And the 16SrRNA gene of strain S5 was amplified, cloned and sequenced, a phylogenetic tree was constructed on the 16SrRNA gene sequences. The tree clearly indicated that strain S5 formed the same lineage with Acidianus brierleyi. Thus strain S5 should be the member of Acidianus. However, there are only 44%, 22% and 23% genomic DNA similarity between S5 and A. brierleyi. A. infernus and A. ambivalens, respectively. And the G + C content of S5 DNA is 38%, which is 5% ~ 7% higher than the reported G + C contents of the other Acidianus species (31% or 32.7%) . In addition, strain S5 is a strictly chemolithoautotrophs, which is obviously different from facultative chemolithotrophs of A brierleyi. Based on the observed differences, strain S5 represents a new species within the genus Acidianus. A new species name, Acidianus tengchongenses, was proposed for it. The type strain is designated S5.

Acidianus↗
PubMed2001

[Study on the Apriona germari(Hope) larvae's intestinal bacterial flora].

Intestinal flora of 47 Apriona germari(Hope) larvae, collected from fields, had been isolated and identified. The results showed that the predominant bacteria were Staphylococcus. Its viable count was 7.63 +/- 0.21, and the detection rate was 100%. Meanwhile, a strain of cellulose-utilizing bacterium was isolated from the fore-midgut fluid of A. germari larvae with the cellulose-congo red agar medium. The bacterium was tentatively identified as Cellulomonas. The detection rate of the cellulolytic bacterium was 23.40%, and the count was 3.84 +/- 0.54 approximately. Its contribution to the borer's cellulose digestion needs further investigations.

Animals↗
PubMed2000

Definition of the anterior choroidal artery territory in rats using intraluminal occluding technique.

This manuscript delineates the territory of the anterior choroidal artery (AChA) in rats, as defined by the induction of an AChA infarction. By advancing a 0.24-mm surgical suture up the internal carotid artery (ICA) to a point 0.5-2 mm proximal to the middle cerebral artery (MCA) origin, the AChA could be occluded and a reliable AChA distribution infarction was produced in 62% (23/37) of animals. The infarct volume, as defined by TTC staining, was 55+/-7 mm(3). Maps of the infarction, generated by measuring the entire area of overlapping coronal slices, demonstrated that the internal capsule was always damaged. Other areas that might be affected included the hippocampus, thalamus, amygdaloid complex, piriform cortex, dorsal caudatoputamen, and lateral ventricular wall. Positioning the coated suture proximal to the AChA produced a much smaller infarct involving the medial and lateral hypothalamus, preoptic region, optic chiasm, and marginal region of the internal capsule near to the lateral hypothalamus exempt from AChA territory damage. A causative relationship between AChA occlusion and a deep cerebral infarct centered on the internal capsule was further established by: (1) identifying the AChA on the non-ischemic side with colored silicone perfusion, and subsequent similar delineation on the ischemic side, and (2) delineating infarction in the silicone perfused AChA region using hematoxylin and eosin staining and the TUNEL method. The AChA usually originated from the ICA (91% of cases), 1.75+/-0.12 mm proximal to the MCA bifurcation. Approximately 27% of the AChAs had periamygdaloid branch(es) on its initial segment.

Animals↗
PubMed2000

Cloning and heterologous expression of a sulfur oxygenase/reductase gene from the thermoacidophilic archaeon Acidianus sp. S5 in Escherichia coli.

A thermoacidophilic, obligately chemolithotrophic, facultatively aerobic archaebacterium, Acidianus sp. S5, was isolated from acidothermal springs in southwest China. The sulfur oxygenase/reductase (SOR) gene of Acidianus sp. S5 was cloned and expressed in Escherichia coli. Several primers were designed and successfully applied for detection and cloning of the sor gene. A 3.7-kb EcoRI fragment containing the sor gene and three neighboring open reading frames was sequenced. Sequence analysis indicated that the sor gene of Acidianus sp. S5 showed 81% identity to the sor gene of Acidianus ambivalens. E. coli cells carrying the sor gene on pBV220SOR were able to overproduce SOR upon a temperature shift from 30 to 42 degrees C. SOR produced in E. coli catalyzes the oxidation of elemental sulfur and concomitant production of sulfite, thiosulfate and hydrogen sulfide. The recombinant enzyme exhibits the same catalytic properties as the one from Acidianus S5.

Amino Acid Sequence↗
PubMed2000

The semaphorin receptor plexin-B1 specifically interacts with active Rac in a ligand-dependent manner.

Semaphorin molecules serve as axon guidance signals that regulate the navigation of neuronal growth cones. Semaphorins have also been implicated in other biological processes, including the immune response. Plexins, acting either alone or in complex with neuropilins, have recently been identified as functional semaphorin receptors. However, the mechanisms of signal transduction by plexins remain largely unknown. We have demonstrated a direct interaction between plexin-B1 and activated Rac. Rac specifically interacts with the cytosolic domain of plexin-B1, but not with that of plexin-A3 or -C1. Neither RhoA nor Cdc42 interacts with plexin-B1, indicating that the Rac/plexin-B1 interaction is highly specific. The binding of GTP and the integrity of the Rac effector domain are required for the interaction with plexin-B1. Furthermore, we have identified that a Cdc42/Rac interactive binding (CRIB) motif in the cytosolic domain of plexin-B1 is essential for its interaction with active Rac. We have also observed that the semaphorin CD100, a ligand for plexin-B1, stimulates the interaction between plexin-B1 and active Rac. Our results support a model by which activated Rac plays a role in mediating semaphorin signals, resulting in reorganization of actin cytoskeletal structure.

Amino Acid Motifs↗
PubMed2000

PCD1, a novel gene containing PDZ and LIM domains, is overexpressed in several human cancers.

In an effort to discover novel genes differentially expressed in human pancreatic cancer, we have identified a gene named PCD1 (pancreatic cancer derived) that is up-regulated in pancreatic dysplasia and cancer relative to normal pancreatic ductal epithelium. We cloned the full length (4572 bp) of this gene, which encodes a novel protein of 1064 amino acids containing a PDZ domain and a LIM domain. An alternatively spliced form with a deletion of 30 bp in the coding region was also found. In situ hybridization results showed that PCD1 is highly expressed in a significant percentage of colon, breast, liver, lung, pancreas, stomach, and prostate tumor tissues but is expressed in very few normal tissues. Northern blot hybridization confirmed the overexpression of PCD1 in colon and breast tumor tissues and also showed strong expression of PCD1 in the heart as well as in HeLa cells. Real-time quantitative reverse transcription-PCR verified the overexpression of PCD1 in primary colon tumors or in liver metastases relative to normal colon tissues in five of eight patients. The PCD1 gene maps to human chromosome 13q21.33. Because of its high levels of expression in neoplastic tissues and the presence of both PDZ and LIM domains, we suggest that PCD1 may play an important role in cytoskeletal reorganization during carcinogenesis.

Amino Acid Sequence↗
PubMed2000

Spatio-temporal interaction with disease mapping.

Markov chain Monte Carlo methods are used to estimate mortality rates under a Bayesian hierarchical model. Spatial correlations are introduced to examine spatial effects relative to both regional and regional changes over time by groups. A special feature of the models is the inclusion of longitudinal variables which will describe temporal trends in mortality or incidences for different population groups. Disease maps are used to illustrate the role of different parameters in the model and pinpointing areas of interesting patterns. The methods are demonstrated by male cancer mortality data from the state of Missouri during 1973-1992. Of special interest will be the geographic variations in the trend of lung cancer mortality over the recent past. Marginal posterior distributions are used to examine effects due to spatial correlations and age difference in temporal trends. Numerical results from the Missouri data show that although spatial correlations exist, they do not have a large effect on the estimated mortality rates.

Aged↗
PubMed2000

Perception of brassinosteroids by the extracellular domain of the receptor kinase BRI1.

An assay was developed to study plant receptor kinase activation and signaling mechanisms. The extracellular leucine-rich repeat (LRR) and transmembrane domains of the Arabidopsis receptor kinase BRI1, which is implicated in brassinosteroid signaling, were fused to the serine/threonine kinase domain of XA21, the rice disease resistance receptor. The chimeric receptor initiates plant defense responses in rice cells upon treatment with brassinosteroids. These results, which indicate that the extracellular domain of BRI1 perceives brassinosteroids, suggest a general signaling mechanism for the LRR receptor kinases of plants. This system should allow the discovery of ligands for the LRR kinases, the largest group of plant receptor kinases.

Arabidopsis↗
PubMed2000

Viral recombinant vaccines to the E6 and E7 antigens of HPV-16.

Most cancerous lesions of the uterine cervix are linked to persistent infections with human papillomaviruses (HPV), most notably HPV-16 or -18. Vaccine-induced immune responses to the HPV early antigens E6 and E7, which contribute to cell transformation and are thus expressed in these cervical cancers, could potentially eradicate malignant cells. We generated recombinant vaccines based on E1-deleted adenovirus human strain 5 or on vaccinia virus strain Copenhagen expressing either the E6 or E7 oncoproteins of HPV-16. The different vaccines were compared in two experimental mouse tumor models employing Balb/c or C57Bl/6 mice. Data presented here demonstrate that depending on the model either CD4(+) or CD8(+) T cells provide protection to tumor cell challenge, resulting in striking differences in the efficacy of the four vaccines under investigation.

Adenoviruses, Human↗
PubMed2000

LMP1 of Epstein-Barr virus suppresses cellular senescence associated with the inhibition of p16INK4a expression.

Epstein-Barr virus is associated with a number of human proliferative and malignant diseases. It is capable of immortalizing human primary B-lymphocytes in vitro. Studies indicate that latent membrane protein LMP1 is one of the viral proteins essential for this process. In this report, LMP1 was shown to prevent primary mouse embryonic fibroblasts from entering into replicative senescence in vitro. It further suppresses the senescence-associated induction of p16INK4a, commonly believed to be a key regulator of replicative senescence. In addition, LMP1 was shown to prevent premature senescence provoked by oncogenic ras in mouse embryonic fibroblasts, and to inhibit the oncogene ras-mediated induction of p16INK4a and p21WAF1. In parallel, LMP1 also prevents ras-induced premature senescence in rat embryonic fibroblasts REF52 and human diploid fibroblasts IMR90. Moreover, LMP1 is capable of suppressing the p16INK4a promoter in REF52 and Saos-2 cells in a promoter reporter assay. Our findings suggest that with the expression of p16INK4a and replicative senescence being suppressed, LMP1 may play a key role in Epstein-Barr virus-associated proliferative diseases, and it may further contribute to cancer development by preventing premature senescence induced by mitogenic oncogenes.

Animals↗
PubMed2000

Characterization of the functionally related sites in the neural inducing gene noggin.

Previously we have shown that blocking bone morphogenetic protein (BMP) receptor signaling by a dominant negative BMP receptor causes neurogenesis in Xenopus animal caps (ACs), whereas the physiological neural inducer noggin acts as a homodimer physically binding to BMP-4 and disrupting its signaling at the ligand level. The present study attempted to elucidate the relationship between the structure and function of noggin. By replacing some cysteine residues with serine residues through a site-directed mutagenesis strategy, we generated three noggin mutants, C145S, C205S, and C(218, 220, 222)S (3CS). Although mRNAs encoded by these mutants were translated as efficiently as wild-type (WT) noggin mRNA, they behaved differently when expressed in vivo. Expression of WT noggin or C205S in Xenopus ACs converted the explants (prospective ectoderm) into neural tissue, indicated by the neural-like morphology and expression of the pan neural marker NCAM in the ACs. In contrast, ACs expressing C145S or 3CS sustained an epidermal fate like the control caps. Similar results were observed in the mesoderm where C205S (but not C145S and 3CS) displayed dorsalizing activity as well as WT noggin. Altogether, our results suggest that Cys145 alone or Cys(218, 220, 222) as a whole in noggin protein is required for the biological activities of noggin, probably participating in the dimerization of noggin with BMP-4 or itself.

Animals↗
PubMed2000

Nuclear factor-kappaB activation is involved in LMP1-mediated transformation and tumorigenesis of rat-1 fibroblasts.

The mechanism of latent membrane protein LMP1 of EBV in inducing cell transformation and tumorigenesis was investigated in Rat-1 fibroblasts. A plasmid encoding a site-specific mutant of LMP1 defective in binding to tumor necrosis factor receptor-associated death domain protein was constructed. This LMP1(TRADD) gene is 75% defective in nuclear factor (NF)-kappaB activation and 100% defective in activator protein-1 activation. When introduced into Rat-1 cells through retrovirus, the Rat-1-LMP1(TRADD) cells showed a significant reduction of focus formation and decreased tumor growth in nude mice as compared with Rat-1-LMP1 cells, suggesting that NF-kappaB or activator protein-1 activation may be important for LMP1-induced cell transformation. To further delineate the determinants of LMP1-mediated cellular transformation, a retrovirus with a dominant-negative I kappaB alpha was introduced into the transformed Rat-1-LMP1 cells. The presence of I kappaB alpha significantly suppressed both focus formation and tumorigenicity of Rat-1-LMP1 cells. Our results suggest that the activation of NF-kappaB may play an important role in LMP1-mediated cell transformation and tumorigenesis.

Animals↗
PubMed2000

Identification of differentially expressed genes in nasopharyngeal carcinoma by means of the Atlas human cancer cDNA expression array.

PURPOSE: To investigate genes of critical areas, including cell cycle/growth control, apoptosis, oncogene/tumor suppressors and growth factor/cytokines, that are differentially expressed in nasopharyngeal carcinoma. METHODS: The Human Cancer cDNA Atlas, which contains 588 genes relating to tumor biology, was used to screen normal nasopharyngeal tissue, nasopharyngeal cancer (NPC). The reverse transcription/polymerase chain reaction was used to confirm the expression pattern of some genes identified by Atlas hybridization. RESULTS: The differentially expressed cell cycle/growth control regulators in NPC showed a stronger tendency toward cell proliferation with the up-regulation of cyclin D1, cyclin D2 etc. The expression pattern of apoptosis-related genes demonstrated the up-regulation of both anti-apoptotic factors such as the BCL-2-related protein A1, TRAF3, the inhibitor of apoptosis protein A1 (IAPI) and apoptotic pathway elements such as Fas/Apo-1, Apo-2 ligand etc. Among oncogenes/tumor suppressors, MDM2, STAT1 and STAT2 were found to be up-regulated in NPC. The expression profile of growth factors/cytokines showed the up-regulation of many growth-enhancing factors such as EGR1, tumor-derived growth factor 1, platelet-derived growth factor A chain etc. as well as Th1-type cytokines e.g. interleukin-1beta and interferons. A smaller number of genes were down-regulated in nasopharyngeal cancer, such as those encoding ERK1, Raf, secreted apoptosis-related protein 1, CD27BP, transforming growth factor beta2, pre-B-cell-stimulating factor homologue etc. CONCLUSION: The consistent tendency toward cell proliferation, the possibility of a stronger antiapoptotic force that operates on the normal apoptotic pathway, or the autocrine or paracrine growth factors may account for the development of NPC. Some genes are reported for the first time to have changed expression in nasopharyngeal carcinoma. The simple, quick, and high-throughput method of profiling gene expression by cDNA array hybridization provides us with a quick overview of key factors that may be involved in NPC, and may identify genes suitable for further study of carcinogenesis mechanism or targets for possible molecular diagnosis or therapy.

Apoptosis↗
PubMed2000

Microbial Biomass and Community Structure in a Sequence of Soils with Increasing Fertility and Changing Land Use.

The microbial biomass and community structure of eight Chinese red soils with different fertility and land use history was investigated. Two community based microbiological measurements, namely, community level physiological profiling (CLPP) using Biolog sole C source utilization tests and phospholipid fatty acid (PLFA) profiles, were used to investigate the microbial ecology of these soils and to determine how land use alters microbial community structure. Microbial biomass-C and total PLFAs were closely correlated to organic carbon and total nitrogen, indicating that these soil microbial measures are potentially good indices of soil fertility in these highly weathered soils. Metabolic quotients and C source utilization were not correlated with organic carbon or microbial biomass. Multivariate analysis of sole carbon source utilization patterns and PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure. PLFAs showed these differences more than CLPP methods. Consequently, PLFA analysis was a better method for assessing broad-spectrum community differences and at the same time attempting to correlate changes with soil fertility. Soils from tea orchards were particularly distinctive in their CLPP. A modified CLPP method, using absorbance readings at 405 nm and different culture media at pH values of 4.7 and 7.0, showed that the discrimination obtained can be influenced by the culture conditions. This method was used to show that the distinctive microbial community structure in tea orchard soils was not, however, due to differences in pH alone.

Journal Article↗