Biomedical subjects

J Zhao

Publications and source records attributed to J Zhao.

At least 37 records · Page 2Linked to original sources

PubMed2006

Biogenesis of chlorophyll-binding proteins under iron stress in Synechocystis sp. PCC 6803.

The biogenesis of chlorophyll-binding proteins under iron stress has been investigated in vivo in a chlN deletion mutant of Synechocystis sp. PCC 6803. The chlN gene encodes one subunit of the light-independent protochlorophyllide reductase. The mutant is unable to synthesis chlorophyll in darkness, causing chlorophyll biosynthesis to become light dependent. When the mutant was propagated in darkness, essentially no chlorophyll and photosystems were detected. Upon return of the chlN deletion mutant to light, 77 K fluorescence emission spectra and oxygen evolution of greening cells under iron-sufficient or -deficient conditions were measured. The gradual blue shift of the photosystem I (PS I) peak upon greening under iron stress suggested the structural alteration of newly synthesized PS I. Furthermore, the rate of biogenesis of PS II was delayed under iron stress, which might be due to the presence of IsiA.

Bacterial Proteins↗

PubMed2006

Gene-activated matrices for cartilage defect reparation.

A cartilage defect has a very limited ability to repair itself spontaneously due to the shortage of blood. Many attempts have been made to restore the integrity of cartilage in clinical and experimental studies. Recently, tissue engineering has emerged as a new protocol for lost tissue regeneration. Meanwhile, the defect-repairing environment can be improved by gene therapy methods. Gene-activated matrices (GAM) fabricated with biomaterials and plasmids fill the cartilage defects to restore the integrity of joint surface, facilitating repair cell adhesion and proliferation as well as the synthesis of extracelluar matrix. And they also serve as a local gene delivery system, inducing therapeutic agent expression at the repair site. In the present study, we fabricated two- and three-dimensional matrices from chitosan and gelatin, then added a plasmid DNA encoding transforming growth factors-ss1 (TGF-ss1) for cartilage defect regeneration. First, we demonstrated primary chondrocytes could maintain their biological characteristics and secrete therapeutic proteins when they were cultured onto GAM in vitro. Subsequently we inserted three-dimensional GAM into cartilage defects of rabbit knee joints. With the results of the new cartilage tissue formation, we came to the conclusion that GAM was helpful for new tissue production and this therapeutic protocol provided a cheap, simple, and effective method for cartilage defect reparation.

Animals↗

PubMed2006

NMR characterization of recombinant transmembrane protein CB2 fragment CB2(180-233).

The expression of membrane proteins has been the bottleneck for their structural studies. Recently, we developed a method to obtain milligram quantities of isotope-labeled seven transmembrane G-protein coupled cannabinoid (CB) receptor fragment in E. coli. In order to verify this method and confirm the recombinant isotope-labeled CB2 fragment, 3D hetero-nuclear NMR techniques were used to analyze the structure of the fragment CB2(180-233) in DMSO-d6 solvent. The sequential assignments of TM5 and intra-cellular loop 3 were accomplished, which confirmed the experimental protocols of isotope-labeled recombinant protein expression, fusion protein cleavage, and membrane protein purification. The obtained structure also showed alpha-helix in the TM5 region, but it was interrupted by a disordered region (Gly204_ILe206). These results further revealed that our established approach is a promising method to express recombinant membrane proteins for their structural studies.

Amino Acid Sequence↗

PubMed2006

Inhibitory effect of Ca(2+) on ATP-mediated stimulation of NPR-A-coupled guanylyl cyclase in renal glomeruli from spontaneously hypertensive and normotensive rats.

Atrial natriuretic peptide (ANP) regulates blood pressure mainly through the occupation of the guanylyl cyclase-coupled receptor NPR-A, which requires ATP interaction for maximal activation. This study investigates the effect of extracellular Ca(2+) on ATP-mediated regulation of NPR-A-coupled guanylyl cyclase activity in glomerular membranes from Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). ATP induced a significant increase in basal and ANP(1-28)-stimulated guanylyl cyclase activity that was greater in SHR than in WKY. Extracellular Ca(2+) inhibited ATP-stimulated guanylyl cyclase activity in a concentration-dependent manner, but did not modify basal and ANP(1-28)-stimulated guanylyl cyclase activity. In the presence of ATP, NPR-A showed higher affinity for ANP(1-28) and lower Bmax. Ca(2+) did not modify NPR-A-ANP(1-28) binding properties. The different effects of extracellular Ca(2+) on ANP(1-28)- or ATP-mediated guanylyl cyclase activation suggest that these events are differentially regulated. Addition of extracellular Ca(2+) induced similar effects in hypertensive and normotensive rats, suggesting that it is not responsible for the elevated cGMP production observed in SHR.

Adenosine Triphosphate↗

PubMed2006

[Comparative study on clinical features of 215 patients with acute and subacute severe hepatitis.].

BACKGROUND: To analyze the clinical features of acute severe hepatitis (ASH) and subacute severe hepatitis (SSH) by comparison analysis. METHODS: The clinical features of 215 cases with ASH and SSH from 1995 to 2005 were retrospectively analyzed by using chi-test, t-test and regression analysis. RESULTS: The most common cause of ASH or SSH was hepatitis B virus (HBV) infection (>30%). Anti-tuberculosis therapy was the main cause of drug-induced ASH or SSH. The incidences of hepatic encephalopathy were 78.13% and 43.05% respectively (P less than 0.001). Prothrombin activity was less than 20% and less than 30%, respectively in cases with ASH and SSH. The most common complications of ASH were hepatic encephalopathy, imbalance of electrolyte and cerebral edema, and that of SSH were ascites, imbalance of electrolyte and hepatic encephalopathy. Prothrombin time, ratio of WBC and neutrophil count were positively related to case fatality of ASH or SSH. Prothrombin activity and total cholesterol (TC) were negatively correlated with fatality of ASH or SSH. Total bilirubin, blood ammonia and creatinine were also positively correlated with fatality of SSH; chlolinesterase, triglyceride, PLT, albumin were negatively correlated with fatality of SSH. CONCLUSION: ASH and SSH are two different entities because of obvious differences in the ages of suffering, the incidence and occurring time of hepatic encephalopathy, abnormality of function of blood coagulation and the marker for predicting prognosis. Severe abnormality of function of blood coagulation is an important marker with high sensitivity and specificity in ASH or SSH patients without hepatic encephalopathy.

Hepatitis↗

PubMed2005

Analysis of the chromosomal region 19q13.4 in two Chinese families with recurrent hydatidiform mole.

BACKGROUND: Familial recurrent hydatidiform mole is an extremely rare autosomal recessive condition in which affected individuals have a predisposition to molar pregnancies that are diploid but biparental, rather than androgenetic, in origin. A gene for this condition has been previously mapped to a 1.1 Mb region of chromosome 19q13.4. However, investigation of further families is needed to refine the location of the specific gene(s) involved. METHODS: We have recently identified two novel Chinese families in which four affected women had recurrent pregnancy loss including 14 complete hydatidiform moles (CHM). Fluorescent microsatellite genotyping was used to determine the origin of CHM in both families. Using a panel of polymorphic microsatellite markers, genotyping and haplotype analysis of the 19q13.4 chromosomal region was performed in both families. RESULTS: Genotyping of CHM from affected individuals confirmed their biparental origin and diagnosis of familial recurrent hydatidiform mole in both families. However, no significant homozygosity for the 19q13.4 candidate region was found in affected members of either family. CONCLUSION: Genotyping and haplotype analysis has shown that a mutation in 19q13.4 is unlikely to be responsible for recurrent CHM in the two Chinese families investigated and provides further evidence to support the hypothesis that, although extremely rare, this condition shows genetic heterogeneity.

China↗

PubMed2005

General rules for predicting phase transitions in perovskites due to octahedral tilting.

Recent experiments on several oxide perovskites reveal that they undergo tilt phase transitions to higher-symmetry phases on increasing pressure and that dTc/dP<0, contrary to a general rule previously proposed for such zone-boundary transitions. We show that the negative slope of the phase boundary is a consequence of the octahedra in these perovskites being more compressible than the extra-framework cation sites. Conversely, when the octahedra are stiffer than the extra-framework cation sites, the phase transition temperatures increase with increasing pressure, dTc/dP>0.

Journal Article↗

PubMed2005

Calcium changes and the response to methyl jasmonate in rice lodicules during anthesis.

Potassium pyroantimonate precipitation was used to locate loosely bound calcium in rice (Oryza sativa L.) lodicules before and after anthesis, and flowering of panicles was accelerated by treatment with methyl jasmonate. From 1 day to 4 h before anthesis, the number of calcium precipitates in the cell walls and vacuole membranes decreased gradually, whereas they increased remarkably in the cytoplasm and nucleolus. At the beginning of anthesis, the number of calcium granules in lodicules reduced sharply, but there was a large accumulation of flocculent precipitates in the vacuoles. After anthesis, the flocculent precipitates decreased in number until they disappeared, whereas the granular precipitates started to accumulate once again. The rice florets treated with 2 mM methyl jasmonate were induced to open within 10-30 min and they then closed 0.5-1 h later. The nucleolus, cytoplasm, and vacuole membrane of the lodicule cells contained many calcium granules during flowering, although the cell walls lacked calcium. At 1 h after treatment, the number of calcium granules had decreased, while flocculent precipitates were regularly observed in the nondegenerated cells. At 6 h after treatment, calcium grains started to reappear in the cell walls. These changes in calcium precipitates before and after anthesis indicate that the opening and closing of florets correlates with the calcium level in lodicule cells. In addition, excised panicles, with florets judged to be nearing anthesis, were soaked in 2-200 mM EGTA solution for 2 min after treatment with 2 mM methyl jasmonate. The results indicate that EGTA had an antagonistic effect on the methyl jasmonate-induced floret opening in rice.

Acetates↗

PubMed2005

Characterization of developmental autolysis in myxobacterial fruiting body morphogenesis with profiling of amino acids using capillary electrophoresis method.

Capillary electrophoresis equipped with Laser-induced fluorescence (CE-LIF), combining with micro-culture technique was employed to determine extracellular amino acids in single myxobacterial fruiting body morphogenesis. The result showed that in the early aggregation stage, there was a remarkable increase of extracellular amino acids, which was produced by developmentally induced autolysis. The amino acids were then consumed by the vegetative cells in aggregation stage. In the following developmental events, the extracellular amino acids were kept at low level, which indicated that in the stages of fruiting body formation and myxospore development, there was no further cell autolysis. Using this novel method may provide detailed insight into the mechanisms of the developmental phenomena.

Amino Acids↗

PubMed2005

The signaling and apoptotic effects of TNF-related apoptosis-inducing ligand in HIV-1 associated dementia.

HIV-1 Associated Dementia (HAD) develops during progressive HIV-1 infection and is characterized by cognitive impairments, behavioral disorders and potential progressive motor abnormality. Abnormal inflammation within the central nervous system (CNS), activation of macrophage/microglia and involvement of proinflammatory cytokines have been suggested as primary factors in the pathogenesis of HAD. Impairment of neuronal function and neuronal cell death are believed to be the end pathophysiological result of HAD. TNF-related apoptosis-inducing ligand (TRAIL), a member of the TNF family of cytokines, was suggested to participate in apoptotic cell death during HAD. As a death ligand, TRAIL was originally thought to target only tumor cells. TRAIL is not typically present in CNS; however, emerging data show that TRAIL can be induced by immune stimuli on macrophage and microglia, major disease effector cells during HAD. Upregulated TRAIL may then cause neuronal apoptosis through direct interaction with TRAIL receptors on neurons or through macrophage death-mediated release of neurotoxins. In this review, we summarize the pivotal role of TRAIL in HAD and TRAIL-initiated intracellular death cascades that culminate in neuronal apoptosis as observed in HAD.

AIDS Dementia Complex↗

PubMed2005

Antitumor effect of beta-elemene in non-small-cell lung cancer cells is mediated via induction of cell cycle arrest and apoptotic cell death.

Beta-elemene is a novel anticancer drug, which was extracted from the ginger plant. However, the mechanism of action of beta-elemene in non-small-cell lung cancer (NSCLC) remains unknown. Here we show that beta-elemene had differential inhibitory effects on cell growth between NSCLC cell lines and lung fibroblast and bronchial epithelial cell lines. In addition, beta-elemene was found to arrest NSCLC cells at G2-M phase, the arrest being accompanied by decreases in the levels of cyclin B1 and phospho-Cdc2 (Thr-161) and increases in the levels of p27(kip1) and phospho-Cdc2 (Tyr-15). Moreover, beta-elemene reduced the expression of Cdc25C, which dephosphorylates/activates Cdc2, but enhanced the expression of the checkpoint kinase, Chk2, which phosphorylates/ inactivates Cdc25C. These findings suggest that the effect of beta-elemene on G2-M arrest in NSCLC cells is mediated partly by a Chk2-dependent mechanism. We also demonstrate that beta-elemene triggered apoptosis in NSCLC cells. Our results clearly show that beta-elemene induced caspase-3, -7 and -9 activities, decreased Bcl-2 expression, caused cytochrome c release and increased the levels of cleaved caspase-9 and poly(ADP-ribose) polymerase in NSCLC cells. These data indicate that the effect of beta-elemene on lung cancer cell death may be through a mitochondrial release of the cytochrome c-mediated apoptotic pathway.

Apoptosis↗

PubMed2005

Antiproliferative effect of beta-elemene in chemoresistant ovarian carcinoma cells is mediated through arrest of the cell cycle at the G2-M phase.

Elemene is a natural antitumor plant drug. However, the effect of elemene on cell growth in ovarian cancer is unknown. In this study, we show that beta-elemene inhibited the proliferation of cisplatin-resistant human ovarian cancer cells and their parental cells, but had only a marginal effect in human ovary cells, indicating differential inhibitory effects on cell growth between ovarian cancer cells and normal ovary cells. We also demonstrated for the first time that beta-elemene markedly enhanced cisplatin-induced growth inhibition in resistant cells compared to sensitive cells. In addition, cell cycle analysis revealed a synergistic effect of beta-elemene and cisplatin on the induction of cell cycle G2-M arrest in our resistant ovarian carcinoma cells. Furthermore, we showed that treatment of these cells with both drugs downregulated cyclin B1 and Cdc2 expression, but elevated the levels of p53, p21waf1/cip1, p27kip1 and Gadd45. Finally, the combination of beta-elemene and cisplatin was found to increase the phosphorylation of Cdc2 and Cdc25C, which leads to a reduction in Cdc2-cyclin B1 activity. These novel findings suggest that beta-elemene sensitizes chemoresistant ovarian carcinoma cells to cisplatin-induced growth suppression partly through modulating the cell cycle G2 checkpoint and inducing cell cycle G2-M arrest, which lead to blockade of cell cycle progression.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2005

An experimental evaluation of ablation devices for the local treatment of the liver resection edge.

UNLABELLED: Surgical margin is the only technical variable that has an impact on long-term outcome after liver resection. In this study we compared radiofrequency (RFA), cryotherapy, diathermy and argon beam for the local treatment of liver resection edge. METHODS: Sixty eight ablations were produced on the surface of ex vivo sheep liver using the various modalities. Cryoablations were produced using both the Cryotech and the Erbe probes. Radiofrequency ablations were produced using a custom-made surface application probe and the RITA 1500 generator. Conmed 7500 system was used to produce diathermy and argon beam coagulation. RESULTS: Argon beam and the diathermy resulted in ablation to maximum depth of 3.5 mm with endpoint and spray modes at various power setting. RF ablation resulted in consistent ablations the diameter of which varied in a linear manner to the time of RF application and the depth of the ablations with the length of electrode deployment. Cryotherapy was as effective as RFA with both the cryotherapy systems but the Erbe trocar probe resulted in a deeper ablation, whereas the Cryotech paddle probe resulted in a larger diameter ablation. CONCLUSIONS: RF and cryotherapy are equally effective as liver edge ablation device. Diathermy and argon are considered less effective. Cryotherapy requires expensive complex equipment that at least with liquid nitrogen systems requires to be prepared for use and this may not be available if the need for edge treatment during resection was unplanned.

Animals↗

PubMed2005

Obstetric complications in patients with schizophrenia and their unaffected siblings.

OBJECTIVE: We sought to explore whether obstetric complications (OCs) are more likely to occur in the presence of familial/genetic susceptibility for schizophrenia or whether they themselves represent an independent environmental risk factor for schizophrenia. METHODS: The presence of OCs was assessed through maternal interview on 216 subjects, comprising 36 patients with schizophrenia from multiply affected families, 38 of their unaffected siblings, 31 schizophrenic patients with no family history of psychosis, 51 of their unaffected siblings and 60 normal comparison subjects. We examined the familiality of OCs and whether OCs were commoner in the patient and sibling groups than in the control group. RESULTS: OCs tended to cluster within families, especially in multiply affected families. Patients with schizophrenia, especially those from multiply affected families, had a significantly higher rate of OCs compared to normal comparison subjects, but there was no evidence for an elevated rate of OCs in unaffected siblings. CONCLUSION: Our data provides little evidence for a link between OCs and genetic susceptibility to schizophrenia. If high rates of OCs are related to schizophrenia genes, this relationship is weak and will only be detected by very large sample sizes.

Adolescent↗

PubMed2005

Detection of porcine circovirus type 2, porcine parvovirus and porcine pseudorabies virus from pigs with postweaning multisystemic wasting syndrome by multiplex PCR.

Multiplex PCR was established to detect porcine circovirus type 2 (PCV-2), porcine parvovirus (PPV) and porcine pseudorabies virus (PRV) and applied to samples from 137 piglets exhibiting clinical signs of postweaning multisystemic wasting syndrome (PMWS). PCV-2 DNA was detected from all samples. Moreover, 43 samples were positive for PPV but negative for PRV; 11 samples were positive for PRV but negative for PPV; and 35 samples were positive both for PPV and PRV. These results suggests that PCV-2 co-infection with PRV and PPV may play an important role in PMWS. Also, multiplex PCR is an appropriate candidate method for diagnosis of PCV-2, PRV and PPV simultaneously in field cases.

Animals↗

PubMed2005

Lentivirus-mediated gene transfer of viral interleukin-10 delays but does not prevent cardiac allograft rejection.

Human immunodeficiency virus (HIV)-based lentiviral vectors expressing viral interleukin-10 (vIL-10) were used to transduce rat cardiac allografts with the aim of extending graft survival. vIL-10 expression was first shown, by RT-PCR, to persist in transduced heart isografts for at least 28 days after transduction. Cardiac transplants were performed in a fully allogeneic rat strain combination (Lewis to DA); allografts transduced by vectors expressing vIL-10 showed significantly prolonged survival (14.5 vs 7.5 days median survival time). Mixed lymphocyte reactions (MLRs) were used to determine the influence, in vitro, of vIL-10 on alloantigen-induced T-cell proliferation. Bioactive vIL-10, produced by DA rat aortic endothelial cells transduced with HIV-PGK-vIL-10, was added to MLRs at different time points and lymphocyte proliferation was assessed by uptake of [3H]thymidine. T-cell proliferation was inhibited by >80% when vIL-10 was added to the MLR at day 1, 2 or 3 of coculture. The inhibitory effect was significantly decreased when addition of vIL-10 was delayed until day 4 or 5 (47 and 35% inhibition, respectively). The extended graft survival time is comparable to that using adenoviral vectors delivering vIL-10 in a similar rat strain combination. The limited improvement in survival may be due to lack of inhibition of the early phase of the alloimmune response as suggested by in vitro studies confirming that maximum suppression of the MLR by vIL-10 can only be achieved if the cytokine is present at the initiation of alloimmune recognition. The delay in expression of vIL-10 from the lentiviral vector means that protocols must be developed to suppress the early stages of alloimmune stimulation before vIL-10 is produced.

Animals↗

PubMed2005

Linkage analysis of chromosome 1 with essential hypertension and blood pressure quantitative traits in Chinese families.

Summary Several recent studies have linked human chromosome 1p to essential hypertension (EH) or blood pressure (BP) levels. In an independent population of 148 hypertensive families from China we tested these findings. Thirty highly informative microsatellite markers spanning about 284 cM were genotyped. Qualitative linkage analysis was conducted using non-parametric linkage analysis implemented within the GENEHUNTER 2.0 software, whereas quantitative analysis was performed with the variance-component method integrated in the S.O.L.A.R. 1.7.4. software with an additional Haseman-Elston method using the SAGE/SIBPAL2 program. We observed suggestive linkage between D1S2890 (1p31, 80.9 cM) and hypertension using the multipoint non-parametric linkage analysis (NPL = 2.19, P = 0.01). In the quantitative analysis we didn't observe a significant excess of identity-by-descent allele sharing between the systolic blood pressure levels and the markers. However, the D1S207 microsatellite marker (1p21) which is located about 107 cM from the telomere of 1p showed weak linkage evidence with the diastolic blood pressure levels (LOD = 1.42). These findings suggest linkage of 1p31 with essential hypertension in the ethnic Chinese, and provide a potential clue for future studies involving candidate genes for hypertension.

Adult↗

PubMed2005

Two new triterpenoid saponins from Symplocos chinensis.

Two new triterpenoid saponins, symplocososides X (1) and Y (2) have been isolated from the roots of Symplocos chinensis, and their structures elucidated as 21beta-O- cinnamoyl-22alpha-O-(2-methylbutanoyl)-15alpha, 16alpha, 28-trihydroxyolean-12-ene-3beta-O-[beta-D-glucopyranosyl (1 --> 2)]-alpha-L-arabinofuranosyl (1 --> 4)-beta-D-glucuronopyranoside (1) and 21beta-O-cinnamoyl-22alpha-O-(2-methylbutanoyl)-15alpha, 16alpha, 28-trihydroxyolean-12-ene-3beta-O-(3-O-acetyl)-[beta-D-glucopyranosyl (1 --> 2)]-alpha-L-arabinofuranosyl (1 --> 4)-beta-D-glucuronopyranoside (2) by spectral and chemical methods. Their antitumor activities have also been tested.

Antineoplastic Agents, Phytogenic↗