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Biomedical subjects

W Zhao

Publications and source records attributed to W Zhao.

At least 145 records · Page 8Linked to original sources
PubMed2000

Mutations in ribosomal protein L16 conferring reduced susceptibility to evernimicin (SCH27899): implications for mechanism of action.

A clinical isolate of Streptococcus pneumoniae (SP#5) that showed decreased susceptibility to evernimicin (MIC, 1.5 microgram/ml) was investigated. A 4,255-bp EcoRI fragment cloned from SP#5 was identified by its ability to transform evernimicin-susceptible S. pneumoniae R6 (MIC, 0.03 microgram/ml) such that the evernimicin MIC was 1.5 microgram/ml. Nucleotide sequence analysis of this fragment revealed that it contained portions of the S10-spc ribosomal protein operons. The nucleotide sequences of resistant and susceptible isolates were compared, and a point mutation (thymine to guanine) that causes an Ile52-Ser substitution in ribosomal protein L16 was identified. The role of this mutation in decreasing susceptibility to evernimicin was confirmed by direct transformation of the altered L16 gene. The presence of the L16 mutation in the resistant strain suggests that evernimicin is an inhibitor of protein synthesis. This was confirmed by inhibition studies using radiolabeled substrates, which showed that the addition of evernimicin at sub-MIC levels resulted in a rapid decrease in the incorporation of radiolabeled isoleucine in a susceptible isolate (SP#3) but was much less effective against SP#5. The incorporation of isoleucine showed a linear response to the dose level of evernimicin. The incorporation of other classes of labeled substrates was unaffected or much delayed, indicating that these were secondary effects.

Amino Acid Sequence↗
PubMed2000

Identification of vaccine candidates for experimental visceral leishmaniasis by immunization with sequential fractions of a cDNA expression library.

Visceral leishmaniasis caused by the intracellular parasite Leishmania donovani is a significant public health problem in many regions of the world. Because of its large genome and complex biology, developing a vaccine for this pathogen has proved to be a challenging task and, to date, protective recombinant vaccine candidates have not been identified. To tackle this difficult problem, we adopted a reductionist approach with the intention of identifying cDNA sequences in an L. donovani amastigote cDNA library that collectively or singly conferred protection against parasite challenge in a murine model of visceral leishmaniasis. We immunized BALB/c mice with plasmid DNA isolated and pooled from 15 cDNA sublibraries ( approximately 2,000 cDNAs/sublibrary). Following systemic challenge with L. donovani, mice immunized with 6 of these 15 sublibraries showed a significantly reduced (35- to 1,000-fold) hepatic parasite burden. Because of the complexity and magnitude of the sequential fractionation-immunization-challenge approach, we restricted our attention to the two sublibraries that conferred the greatest in vivo protection. From one of these two sublibraries, we identified several groups of cDNAs that afforded protection, including a set of nine novel cDNAs and, surprisingly, a group of five cDNAs that encoded L. donovani histone proteins. At each fractionation step, the cDNA sublibraries or the smaller DNA fractions that afforded in vivo protection against the parasite also induced in vitro parasite-specific T helper 1 immune responses. Our studies demonstrate that immunization with sequential fractions of a cDNA library is a powerful strategy for identifying anti-infective vaccine candidates.

Animals↗
PubMed2000

Assembly of retrovirus capsid-nucleocapsid proteins in the presence of membranes or RNA.

Retrovirus Gag precursor (PrGag) proteins direct the assembly of roughly spherical immature virus particles, while after proteolytic processing events, the Gag capsid (CA) and nucleocapsid (NC) domains condense on viral RNAs to form mature retrovirus core structures. To investigate the process of retroviral morphogenesis, we examined the properties of histidine-tagged (His-tagged) Moloney murine leukemia (M-MuLV) capsid plus nucleocapsid (CANC) (His-MoCANC) proteins in vitro. The His-MoCANC proteins bound RNA, possessed nucleic acid-annealing activities, and assembled into strand, circle (or sphere), and tube forms in the presence of RNA. Image analysis of electron micrographs revealed that tubes were formed by cage-like lattices of CANC proteins surrounding at least two different types of protein-free cage holes. By virtue of a His tag association with nickel-chelating lipids, His-MoCANC proteins also assembled into planar sheets on lipid monolayers, mimicking the membrane-associated immature PrGag protein forms. Membrane-bound His-MoCANC proteins organized into two-dimensional (2D) cage-like lattices that were closely related to the tube forms, and in the presence of both nickel-chelating lipids and RNAs, 2D lattice forms appeared similar to lattices assembled in the absence of RNA. Our observations are consistent with a M-MuLV morphogenesis model in which proteolytic processing of membrane-bound Gag proteins permits CA and NC domains to rearrange from an immature spherical structure to a condensed mature form while maintaining local protein-protein contacts.

Amino Acid Sequence↗
PubMed2000

Cells degrade a novel inhibitor of differentiation with E1A-like properties upon exiting the cell cycle.

Control of proliferation and differentiation by the retinoblastoma tumor suppressor protein (pRB) and related family members depends upon their interactions with key cellular substrates. Efforts to identify such cellular targets led to the isolation of a novel protein, EID-1 (for E1A-like inhibitor of differentiation 1). Here, we show that EID-1 is a potent inhibitor of differentiation and link this activity to its ability to inhibit p300 (and the highly related molecule, CREB-binding protein, or CBP) histone acetylation activity. EID-1 is rapidly degraded by the proteasome as cells exit the cell cycle. Ubiquitination of EID-1 requires an intact C-terminal region that is also necessary for stable binding to p300 and pRB, two proteins that bind to the ubiquitin ligase MDM2. A pRB variant that can bind to EID1, but not MDM2, stabilizes EID-1 in cells. Thus, EID-1 may act at a nodal point that couples cell cycle exit to the transcriptional activation of genes required for differentiation.

Acetyltransferases↗
PubMed2000

Chronic metabolic sequelae of traumatic brain injury: prolonged suppression of somatosensory activation.

Injuries to the brain acutely disrupt normal metabolic function and may deactivate functional circuits. It is unknown whether these metabolic abnormalities improve over time. We used 2-deoxyglucose (2-DG) autoradiographic image-averaging to assess local cerebral glucose utilization (lCMR(Glc)) of the rat brain 2 mo after moderate (1.7-2.1 atm) fluid-percussion traumatic brain injury (FPI). Four animal groups (n = 5 each) were studied: sham-injured rats with and without stimulation of the vibrissae-barrel field ipsilateral to injury; and animals with prior FPI, with or without this stimulation. In sham-injured rats, resting lCMR(Glc) was normal, and vibrissae stimulation produced right-sided metabolic activation of the ventrolateral thalamic and somatosensory-cortical projection areas. In rats with prior injury, lCMR(Glc) contralateral to injury was normal, but lCMR(Glc) of the ipsilateral forebrain was depressed by approximately 38-45% compared with shams. Whisker stimulation in rats with prior trauma failed to induce metabolic activation of either cortex or thalamus. Image-mapping of histological material obtained in the same injury model was undertaken to assess the possible influence of injury-induced regional brain atrophy on computed lCMR(Glc); an effect was found only in the lateral cortex at the trauma epicenter. Our results show that, 2 mo after trauma, resting cerebral metabolic perturbations persist, and the whisker-barrel somatosensory circuit shows no signs of functional recovery.

Animals↗
PubMed2000

Osteocyte and osteoblast apoptosis and excessive bone deposition accompany failure of collagenase cleavage of collagen.

Mice carrying a targeted mutation (r) in Col1a1, encoding a collagenase-resistant form of type I collagen, have altered skeletal remodeling. In hematoxylin and eosin-stained paraffin sections, we detect empty lacunae in osteocytes in calvariae from Col1a1(r/r) mice at age 2 weeks, increasing through age 10-12 months. Empty lacunae appear to result from osteocyte apoptosis, since staining of osteocytes/periosteal osteoblasts with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling is increased in Col1a1(r/r) relative to wild-type bones. Osteocyte perilacunar matrices stained with Ab that recognizes collagenase collagen alpha1(I) chain cleavage ends in wild-type but not Col1a1(r/r) calvariae. Increased calvarial periosteal and tibial/femoral endosteal bone deposition was found in Col1a1(r/r) mice from ages 3-12 months. Calcein labeling of calvarial surfaces was increased in Col1a1(r/r) relative to wild-type mice. Daily injections of synthetic parathyroid hormone for 30 days increased calcein-surface labeling in wild-type but caused no further increase in the already high calcein staining of Col1a1(r/r) bones. Thus, failure of collagenase cleavage of type I collagen in Col1a1(r/r) mice is associated with osteocyte/osteoblast death but increases bone deposition in a manner that mimics the parathyroid hormone-induced bone surface activation seen in wild-type mice.

Animals↗
PubMed2000

Molecular cloning, expression, and characterization of rat homolog of human AP-2alpha that stimulates neuropeptide Y transcription activity in response to nerve growth factor.

Neuropeptide Y (NPY) plays an important role in the central regulation of neuronal activity, endocrine and sexual behavior, and food intake. Although transcription activity of the NPY gene in PC12 cells is regulated by a number of agents such as nerve growth factor (NGF), the mechanism responsible for the NGF-elicited increase in the transcription of the NPY gene remains to be explored. In this study, we isolated and characterized a nuclear protein that is bound to NGF-response elements (NGFRE) that lie between nucleotide -87 and -33 of the rat NPY promoter gene. This nuclear protein is identical to the rat homolog of human transcription factor AP-2alpha. We further demonstrated that rat AP-2a promotes efficient NPY transcription activity in response to NGF. Finally, we provide direct evidence that the mice lacking transcription factor AP-2alpha exhibit reduced expression of NPY mRNA compared with wild-type mice, further supporting the hypothesis that AP-2alpha is an important transcription factor in regulating NPY transcription activity.

Amino Acid Sequence↗
PubMed2000

Comparative neuroprotective efficacy of prolonged moderate intraischemic and postischemic hypothermia in focal cerebral ischemia.

OBJECT: The purpose of this study was to compare the effects of prolonged hypothermia on ischemic injury in a highly reproducible model of middle cerebral artery (MCA) occlusion in rats. METHODS: Male Sprague-Dawley rats were anesthetized with halothane and subjected to 120 minutes of temporary MCA occlusion by retrograde insertion of an intraluminal nylon suture coated with poly-L-lysine through the external carotid artery into the internal carotid artery and the MCA. Two levels of prolonged postischemic cranial hypothermia (32 degrees C and 27 degrees C) and one level of intraischemic cranial hypothermia (32 degrees C) were compared with the ischemic normothermia (37 degrees C) condition. Target cranial temperatures were maintained for 3 hours and then gradually restored to 35 degrees C over an additional 2-hour period. The animals were evaluated using a quantitative neurobehavioral battery of tests before inducing MCA occlusion, during occlusion (at 60 minutes postonset in all rats except those in the intraischemic hypothermia group), and at 24, 48, and 72 hours after reperfusion. The rat brains were perfusion fixed at 72 hours after ischemia, and infarct volumes and brain edema were determined. Both intraischemic and postischemic cooling to 32 degrees C led to similar significant reductions in cortical infarct volume (by 89% and 88%, respectively) and total infarct volume (by 54% and 69%, respectively), whereas postischemic cooling to 27 degrees C produced lesser reductions (64% and 49%, respectively), which were not statistically significant. All three hypothermic regimens significantly lessened hemispheric swelling and improved the neurological score at 24 hours. The authors' data confirm that a high degree of histological neuroprotection is conferred by postischemic cooling to 32 degrees C, which is virtually equivalent to that observed with intraischemic cooling to the same level. CONCLUSIONS: These results may be relevant to the design of future clinical trials of therapeutic hypothermia for acute ischemic stroke.

Animals↗
PubMed2000

[Cloning and primary analysis of 3 'end genome of two alphaviruses isolated from Hainan Province of China].

OBJECTIVE: To further characterize the HBbl7 and Ml viruses isolated from Hainan Province by molecular biology. METHODS: The fragment containing partial El and 3'untranslated region of each of the viral isolate was amplified by RT-PCR, then subcloned. Recombinant was screened and sequenced. Analysis and comparison were carried out. RESULTS: 1.6kb fragment was amplified from HBbl7 and a 1.3kb was from Ml Comparison of sequences showed, in 3'untranslated region the nucleotide homology between HBbl7 and T48, the prototype of Ross River virus, is 99%, between Ml and Sagiyama virus is 98%. In the partial El sequence, the nucleotide (amino acid) homology between HBbl7 and T48 is 99%(99%),between Ml and Sagiyama virus is 97%(99%), and between Ml and Cetah virus is 94% (98%). CONCLUSIONS: Sequence analysis showed HBb17 virus belongs to Ross River virus, Ml virus belongs to Sagiyama virus or Cetah virus.

Alphavirus↗
PubMed2000

[Effects of salinity and alkalinity on plankton and water chemical factors].

This paper dealt with the effects of increasing salinity and alkalinity on the chemical and hydrobiological factors in saline-alkaline ponds. The experiment was conducted in Daluhu Aquaculture Company, Gaoqing County, Shandong Province during July and August, 1998. Raw salt and NaHCO3 were used to adjust the salinity and alkalinity. The results showed that increasing alkalinity from HCO3- rsulted in the reduction of pH value, calcium ion concentration and COD in a short term. When alkalinity was increased from 6.64 +/- 0.40 to 13.47 +/- 0.31 mmol.L-1, no significant effect on plankton was observed. However, when salinity was increased from 2.10 +/- 0.22 to 11.29 +/- 0.99 g.L-1, it decreased the plankton biomass, species number and diversity index decreased, and affected the composition of plankton community structure.

Animals↗
PubMed2000

Hemostatic abnormalities associated with acute promyelocytic leukemia and corrective effects of all-trans-retinoic acid or arsenic trioxide treatment.

OBJECTIVE: To study in vivo effect of all-trans-retinoic acid (ATRA) or arsenic trioxide (As2O3) on the expression of tissue factor (TF) and the hemostatic disorders, a series of parameters were measured in bone marrow blasts and plasma from acute promyelocytic leukemia (APL) patients. METHODS: The plasma variables were measured by ELISA or chromogenic study. The TF transcription was assessed using reverse transcription-polymerase chain reaction technique (RT-PCR). RESULTS: The blast cell procoagulant activity (PCA), TF antigen of APL cell lysates, as well as the transcription of APL TF mRNA elevated at diagnosis, were reduced after ATRA or As2O3 therapy. The plasma level of platelet alpha-granular membrane protein-140, soluble fibrinomonomer complex, thrombomodulin, tissue plasminogen activator and D-dimer significantly increased, fibrinogen, antigen level of protein C, plasminogen, alpha 2-plasminogen inhibitor and plasminogen activator inhibitor decreased at diagnosis, were restored to normal after complete remission but protein C activity and protein S remained elevated in ATRA group. CONCLUSIONS: There existed activation of platelets and consumption of anticoagulants as well as activation of coagulation and fibrinolytic system before treatment. Both ATRA and As2O3 therapy down-regulated the expression of TF mRNA, decreased the PCA and TF level in APL cells, inhibited coagulation activation, secondary hyperfibrinolysis and recorrected other hemostatic abnormalities, thus greatly improved the bleeding symptom in early stage of the treatment.

Adolescent↗
PubMed2000

Impact of RT-PCR monitoring on the long-term survival in acute promyelocytic leukemia.

OBJECTIVE: To evaluate the impact of kinetics of molecular remission via retro-transcriptase polymerase chain reaction (RT-PCR) assay on the long-term survival in patients with acute promyelocytic leukemia (APL). METHODS: Seventy patients with newly-diagnosed APL in remission were involved in this study. Monitoring of minimal residual disease (MRD) was performed regularly by RT-PCR assay for PML-RAR alpha during consolidation. RESULTS: A 5-year relapse-free survival (RFS) and overall-survival (OS) were estimated as 46.8% +/- 8.4% and 69.9% +/- 9.4% for the whole group. Fifty-two (74.3%) patients got negative RT-PCR result at least once. Serial monitoring of RT-PCR was available in 38 cases and 24 (63.2%) patients presented with persistent negative PCR results. The achievement and continuous negative RT-PCR result was significantly related to the RFS. CONCLUSIONS: Achievement of negative RT-PCR in remission is associated with favorable RFS and OS. Continuous negative RT-PCR results are associated with long-term relapse-free survival and may be considered as potentially curative. RT-PCR assay for detection of MRD should be performed regularly during post-remission period as an important prognostic factor.

Adolescent↗
PubMed2000

[Relationship between isometric exercise and myocardial ischemia in patients with coronary artery disease: an Echo-Doppler study].

OBJECTIVE: To study the relationship between isometric exercise and myocardial ischemia in patients with coronary artery disease (CAD). METHODS: Twenty CAD patients and 10 normal subjects were included in our study. All subjects performed maximal brief isometric exercise (BIE), maximal sustained isometric exercise (SIE) and dynamic exercise (DE). Hemodynamic parameters and cardiac function were measured by Echo-Doppler technique. To avoid influence of different baseline values, increment (delta%) of exercise response was used as parameter for significant analysis: delta% = (exercise values - baseline values)/baseline values x 100%. RESULTS: Positive exercise testing (PET) showed no evidence of myocardial ischemia during BIE and SIE even though their rates of perceived exertion (RPE) were similar to DE. delta% heart rate (HR) and delta% rate pressure product (RPP) were higher during DE than during SIE and BIE in negative exercise testing (NET) and normal controls (NOR) (P < 0.01), except PET during DE and SIE; delta% systolic blood pressure (SBP) was higher during DE than during BIE in NOR (P < 0.01). delta% SBP in NOR and NET during SIE was higher than during BIE (P < 0.05). delta% diastolic blood pressure (DBP) was the highest during SIE among exercises in all gropus (P < 0.05). There were no significant inter-group differences of delta% HR, delta% SBP, delta% DBP and delta% RPP during SIE, BIE and DE, except that delta% SBP during SIE was higher in NET than in NOR and PET (P < 0.05). In NOR, delta% ejection fraction (EF), delta% fractional shortening of the minor-semi axis (SF), delta% cardiac output (CO), delta% E/A was higher during DE than during SIE and BIE (P < 0.01). delta% stroke volume (SV) was similar during DE, SIE and BIE. There were no significant differences in delta% EF, delta% SF, delta% CO, delta% SV and delta% E/A during DE, SIE and BIE in both NET and PET, except lower delta% CO in NET during SIE and BIE than DE (P < 0.01). There were no inter-group differences in delta% EF, delta% SF, delta% CO and delta% E/A, except that delta% E/A was higher during SIE in NET than PET (P < 0.01). During DE, NOR and NET had higher delta% SV, delta% SF, delta% CO and delta% E/A than PET (P < 0.05). CONCLUSIONS: The incidence of myocardial ischemia in CAD patients was lower during isometric exercise than dynamic exercise at similar perceived exertion levels. Isometric exercise might protect the myocardium from ischemia through high coronary artery perfusion pressure and long perfusion duration. We suggest that application of isometric exercise in a cardiac rehabilitation program may have reasonable physiological background.

Aged↗
PubMed2000

[The mechanism of docetaxel-induced apoptosis in human lung cancer cells].

OBJECTIVE: To study the mechanism of docetaxel-induced apoptosis. METHODS: Morphological study, DNA gel electrophoresis, flow cytometry and fluorescin labeled Annexin V to detect apoptosis, RT-PCR to detect the gene related with apoptosis. RESULTS: Human lung cancer A549 cells treated with docetaxel induced cell cycle arrest at G2M phase, leading to apoptosis. The morphology of A549 showed nuclear chromatine condensation and fragmentation. Typical ladder pattern of DNA fragmentation was observed. Sub-G1 peak was found by flow cytometry. Transcription of Fas gene was enhanced, while no change in c-myc and bcl-2 genes. Annexin labeling results revealed the co-existence of cell apoptosis and necrosis in docetaxel-treated A549 cells. CONCLUSION: Docetaxel induces apoptosis and necrosis of human lung cancer. The induction of apoptosis may be related to expression of Fas.

Annexin A5↗
PubMed2000

[Effect of yiqi yangyin huoxue recipe on endothelin and nitric oxide of type 2 diabetic patients with deficiency of both Qi-Yin and blood stasis syndrome].

OBJECTIVE: To study the effect of Yiqi Yangyin Huoxue recipe (YQYYHX) in treating type 2 diabetes mellitus (DM) patients with deficiency of both Qi-Yin (DQY) and blood stasis Syndrome. METHODS: Forty-one type 2 DM patients compared with those in the control group were observed. RESULTS: After treatment, the endothelin (ET) level of the treated group reduced significantly, and the total effective rate of blood sugar lowering were as follows: Fasting blood glucose (FBG) 87.80%, 2 hours postprandial plasma blood glucose (PBG) 90.24%. CONCLUSION: YQYYHX is effective in improving the patient's vascular endothelia cell functions by reducing the plasma ET level, clinical symptoms and blood sugar lowering.

Adult↗
PubMed2000

[Clinical study on treatment of mild-middle degree congestive heart failure with integrated traditional Chinese and Western medicine].

OBJECTIVE: To evaluate the effect of combined use of Chinese herbal medicine, Captopril and Metoprolol in treating mild-middle degree congestive heart failure. METHODS: One hundred and fifty patients studied were divided into 3 groups, the Group A treated with Chinese herbal medicine, Group B treated with Captopril plus Metoprolol and Group C treated with both Chinese and western medicines. Parameters on cardiac functions were observed and compared 3 weaks and 3 months after treatment respectively. RESULTS: (1) The cure rate in the Group A, B and C was 72%, 86% and 94% respectively. (2) Effect of echocardiogram: ultrasound cardiogram showed that the left ventricular diastolic diameter in Group C was less significantly than that in Group A and B (P < 0.05). (3) The eject fraction in Group C was higher than that in the other two groups (P < 0.05). (4) The 24 hours dynamic electrocardiogram demonstrated a significant lowering occurrence of ventricular premature contraction in Group C in comparing with that in Group A and B (P < 0.05). CONCLUSION: Good effect would be expected in treating mild-middle degree congestive heart failure by using Chinese herbal medicine combined with Captopril and Metoprolol.

Adrenergic beta-Antagonists↗
PubMed2000

[Effects of all-trans retinoic acid and arsenic trioxide on tissue factor expression of acute promyelocytic leukemia cells].

OBJECTIVE: To investigate the effects of all-trans retinoic acid (ATRA) and arsenic trioxide (As(2)O(3)) on both tissue factor (TF) expression and procoagulant activity (PCA) of acute promyelocytic leukemia (APL) cells in vivo and in vitro. METHODS: The PCA of APL blasts freshly isolated from the APL patients treated with ATRA or As(2)O(3) was detected using a one-stage clotting assay; the TF antigen was detected by ELISA and TF mRNA by RT-PCR. The maturation sensitivity (NB4) or resistant subclones (NB4-R1) of the promyelocytic NB4 cell line as well as U937 cells transfected with pMSCV-PML-RARa treated with or without ATRA or As(2)O(3) were also examined. RESULTS: Both ATRA and As(2)O(3) time-dependently down-regulated the TF antigen, its mRNA transcription and membrane PCA of APL cells in vivo and in vitro. The TF antigen level in PML-RARa(+) U937 cells was significantly higher than that in U937 cells transfected with retrovirus vector (890 pg/8 x 10(5) +/- 80 pg/8 x 10(5) cell and 728 pg/8 x 10(5) +/- 86 pg/8 x 10(5) cell, respectively). Both ATRA and As(2)O(3) down-regulated the TF antigen of the U937 cells transfected with or without PML-RARa. CONCLUSION: Tissue factor expression and PCA of APL cells can be down-regulated by ATRA and As(2)O(3). By down-regulating the TF expression, As(2)O(3) might also be used to improve the DIC-related hemorrhage of APL. It is also suggested that elevated TF antigen in the PML-RARa(+) U937 cells may be related with the fusion protein PML-RARa, while the down-regulation effect of ATRA and As(2)O(3) on the TF expression of U937 cells might not be involved in the fusion protein.

Adolescent↗