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Biomedical subjects

M Zhao

Publications and source records attributed to M Zhao.

At least 55 records · Page 3Linked to original sources
PubMed2001

[The inducibility of Amp C enzyme of Enterobacter cloacae and its susceptibility to enzyme inhibitor].

OBJECTIVE: To study the inducibility of Amp C enzyme of Enterobacrter cloacae and its susceptibility to enzyme inhibitor. METHODS: The in vitro activities of the fourth generation cephalosporins-cefepime, the third generation cephalosporins-cefuroxime, cefotaxime, ceftazidime combined with beta-lactamase inhibitor sulbactam against 10 strains of ceftazidime resistant Enterobacter cloacae selected from the hospitals was studied with agar two fold dilution method. The inducibility of beta-lactam antibiotics in common use clinically to Amp C enzyme and the inhibitory action of 3 inhibitors to Amp C enzyme were studied with ultraviolet spectrophotometry and RTPCR. RESULTS: Sulbactam can not enhance the activity of ceftazidime against Enterobacter cloacae. Cefepime has a strong activity against ceftazidime resistant Enterobacter cloacae. Imipenem has a strong inductive action to Amp C enzyme. Ro481220 has a strong inhibitory action to Amp C enzyme. CONCLUSION: Infections caused by Enterobacter cloacae producing Amp C enzyme can be treated by cefepime.

Bacterial Proteins↗
PubMed2001

Repression of the HSP70B promoter by NFIL6, Ku70, and MAPK involves three complementary mechanisms.

We have studied mechanisms of HSP70 gene regulation at 37 degrees C by the cellular factors NF-IL6 and Ku70. As both factors repress HSF1, we first examined whether phosphorylation on serine 303 and 307 of HSF1 by MAPK and GSK3, which has known to inhibit HSF1, was involved in the repression. However, repression by NF-IL6 was found using HSF1 mutants S303G and S307G refractory to the effects of MAPK and GSK3. We then examined whether NF-IL6 repressed HSP70B by a mechanism resembling Ku proteins. However, in Ku-deficient cells, NF-IL6 was still able to displace HSF1 from heat shock element (HSE) and repressed HSF1 activation. In addition, activation of the HSP 70B promoter by wild type, S303G, or S307G HSF1 was observed to be much more pronounced in Ku-deficient cells. In vitro translated Ku70 interacted with HSF1 by binding to and displacing it from HSE. These data indicate that the repression of the HSP70B promoter by NF-IL6, Ku70, and MAPK occurs independently of each other and involves three complementary mechanisms.

Amino Acid Substitution↗
PubMed2001

Defect in SHAP-hyaluronan complex causes severe female infertility. A study by inactivation of the bikunin gene in mice.

Hyaluronan (HA) associates with proteins and proteoglycans to form the extracellular HA-rich matrices that significantly affect cellular behaviors. So far, only the heavy chains of the plasma inter-alpha-trypsin inhibitor (ITI) family, designated as SHAPs (serum-derived hyaluronan-associated proteins), have been shown to bind covalently to HA. The physiological significance of such a unique covalent complex has been unknown but is of great interest, because HA and the ITI family are abundant in tissues and in plasma, respectively, and the SHAP-HA complex is formed wherever HA meets plasma. We abolished the formation of the SHAP-HA complex in mice by targeting the gene of bikunin, the light chain of the ITI family members, which is essential for their biosynthesis. As a consequence, the cumulus oophorus, an investing structure unique to the oocyte of higher mammals, had a defect in forming the extracellular HA-rich matrix during expansion. The ovulated oocytes were completely devoid of matrix and were unfertilized, leading to severe female infertility. Intraperitoneal administration of ITI, accompanied by the formation of the SHAP-HA complex, fully rescued the defects. We conclude that the SHAP-HA complex is a major component of the HA-rich matrix of the cumulus oophorus and is essential for fertilization in vivo.

Alpha-Globulins↗
PubMed2001

Monitoring of biological responses of tumor cells after irradiation with 99mTc-MIBI--an in vitro study.

To explore the possibility to employ 99mTc-MIBI to monitor biological response of tumor cells after irradiation and to observe the relation between the radiation doses and the uptake levels of 99mTc-MIBI in tumor cells, the cells were irradiated with a single dose of 2 Gy, 10 Gy and 20 Gy respectively. The uptake of 99mTc-MIBI in each dosage group was determined before and 24, 48, 72 h after irradiation respectively. Apoptosis index (AI), plating efficiency (PE) of tumor cells was simultaneously determined. There was a positive correlation between uptake levels of 99mTc-MIBI and AI(r = -0.91, P < 0.05). A negative correlation was noted between the uptake levels and PE (r = -0.86, P < 0.05). It is suggested that 99mTc-MIBI may be used as a tracer to monitor the change of viability state of tumor cells after being irradiated with different doses.

Animals↗
PubMed2001

Dynamic renal scintigraphy in diagnosis of upper urinary tract obstruction in transplanted kidney.

Nuclide renal dynamic imaging was performed on 88 (110 times) transplanted kidney. Two kinds of renal scintigraphic characteristics were identified in recipients with supravesical obstruction of the graft. First, the regular type was characterized by radioactivity defect area in kidney parenchyma during early uptake period followed by ureteropelvic retention. Second, the tubular type was typified by cortical retention and attenuation in collecting system during the whole test period with a special sign of "hollow kidney". Non-obstructive dilated calyces showed similar signs as the regular type. Acute rejection reaction and tubule necrosis demonstrated obstructive time-activity curves. However, the radioactivity retention appeared in cortex. It was suggested that dilated calyces and obstructive renogram might not be reliable evidence for upper urinary tract obstruction. The signs of radioactivity attenuation in kidney parenchyma during early uptake period followed by ureteropelvic retention may be more valuable for the evaluation. As for tubular obstruction, specified "hollow kidney" was the characteristic sign which is helpful for the diagnosis.

Adolescent↗
PubMed2001

Cytokine expression in rat molar gingival periodontal tissues after topical application of lipopolysaccharide.

It is well known that proinflammatory cytokines produced by host cells play an important role in periodontal tissue destruction. However, the localization of the cytokines in in vivo periodontal tissues during development of periodontal disease has not been determined. Immunohistochemical expression of proinflammatory cytokines including IL-1alpha, IL-1beta, and TNF-alpha was examined at 1 and 3 h, and 1, 2, 3, and 7 days after topical application of lipopolysaccharide (LPS; 5 mg/ml in physiological saline) from E. coli into the rat molar gingival sulcus. In the normal periodontal tissues, a small number of cytokine-positive epithelial cells were seen in the junctional epithelium (JE), oral sulcular and oral gingival epithelium, in addition to macrophages infiltrating in the subjunctional epithelial area and osteoblasts lining the alveolar bone surface. Epithelial remnants of Malassez existing throughout periodontal ligament were intensely positive for IL-1beta but negative for the other two cytokines. At 3 h after the LPS treatment, almost all cells in the JE were strongly positive for the cytokines examined. In addition, several cytokine-positive cells, including neutrophils, macrophages, and fibroblasts, were seen in the subjunctional epithelial connective tissue. At day 2, expression of the cytokines in the JE gradually decreased, while cytokine-positive cells in the connective tissue increased in number. Positive staining of the cytokines was seen in osteoclasts and preosteoclasts which appeared along the alveolar bone margin in this period. The number of cytokine-positive cells decreased by day 7. These findings indicate that, in addition to macrophages, neutrophils, and fibroblasts, the JE cells are a potent source of TNF-alpha, IL-1alpha, and IL-1beta reacting to LPS application, and suggest that JE cells may play an important role in the first line of defense against LPS challenge, and the proinflammatory cytokines transiently produced by various host cells may be involved in the initiation of inflammation and subsequent periodontal tissue destruction.

Animals↗
PubMed2001

Synthesis and analgesic effects of kyotorphin-steroid linkers.

Kyotorphin (KTP, H-Tyr-Arg-OH) was covalently bonded with hydrocortisone or estrone to form the corresponding hydrocortisone-21-O-yl-succinyl-Tyr-ArgOH or estrone-3-O-yl-acyl-Tyr-Arg-OH. Their analgesic activities were investigated using the tail flick test. The potency of the two linkers were significantly higher than that of KTP and the mixture of KTP and hydrocortisone or estrone in the CNS and/or the periphery administration.

Analgesics↗
PubMed2001

Dendrimer-encapsulated metal nanoparticles: synthesis, characterization, and applications to catalysis.

This Account reports the synthesis and characterization of dendrimer-encapsulated metal nanoparticles and their applications to catalysis. These materials are prepared by sequestering metal ions within dendrimers followed by chemical reduction to yield the corresponding zerovalent metal nanoparticle. The size of such particles depends on the number of metal ions initially loaded into the dendrimer. Intradendrimer hydrogenation and carbon-carbon coupling reactions in water, organic solvents, biphasic fluorous/organic solvents, and supercritical CO2 are also described.

Biocompatible Materials↗
PubMed2001

Non-invasive detection of apoptosis using magnetic resonance imaging and a targeted contrast agent.

The C2 domain of synaptotagmin I, which binds to anionic phospholipids in cell membranes, was shown to bind to the plasma membrane of apoptotic cells by both flow cytometry and confocal microscopy. Conjugation of the protein to superparamagnetic iron oxide nanoparticles allowed detection of this binding using magnetic resonance imaging. Detection of apoptotic cells, using this novel contrast agent, was demonstrated both in vitro, with isolated apoptotic tumor cells, and in vivo, in a tumor treated with chemotherapeutic drugs.

Animals↗
PubMed2001

Molecular cytogenetic characterization and clinical relevance of additional, complex and/or variant chromosome abnormalities in acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is characterized by typical morphological manifestation, t(15;17) translocation and active response to all-trans retinoic acid (ATRA) in the great majority of patients. However, a subset of APL cases may present atypical phenotypic, cytogenetic or molecular features at different stages of the disease. The biological and clinical significance of these features sometimes remains obscure. In this study, 284 APL patients were cytogenetically analyzed and precise diagnosis was performed according to the molecular cytogenetic results. Twenty-six APL patients were identified as having additional, complex and/or variant chromosomal abnormalities at diagnosis or at relapse, 16 of them being further analyzed using fluorescence in situ hybridization (FISH) or chromosome painting (CP). Interestingly, some of these chromosomal aberrations were found to be associated with atypical morphology and/or drug response, indicating a genotype-phenotype correlation. Analysis of the complex karyotype may also allow a better understanding of the levels of cellular origin of the leukemogenesis. Examination of the remission induction and survival data showed that the presence of the additional/complex chromosome abnormalities was related to the prognosis in both primarily diagnosed and relapsed patients in this series.

Adolescent↗
PubMed2001

The recovery of cognitive function after general anesthesia in elderly patients: a comparison of desflurane and sevoflurane.

UNLABELLED: We evaluated the cognitive recovery profiles in elderly patients after general anesthesia with desflurane or sevoflurane. After IRB approval, 70 ASA physical status I-III consenting elderly patients (> or =65 yr old) undergoing total knee or hip replacement procedures were randomly assigned to one of two general anesthetic groups. Propofol and fentanyl were administered for induction of anesthesia, followed by either desflurane 2%-4% or sevoflurane 1%-1.5% with nitrous oxide 65% in oxygen. The desflurane (2.5 +/- 0.6 MAC. h) and sevoflurane (2.7 +/- 0.5 MAC. h) concentrations were adjusted to maintain comparable depths of hypnosis using the electroencephalogram bispectral index monitor. The Mini-Mental State (MMS) test was used to assess cognitive function preoperatively and postoperatively at 1, 3, 6, and 24-h intervals. The use of desflurane was associated with a more rapid emergence from anesthesia (6.3 +/- 2.4 min versus 8.0 +/- 2.8 min) and a shorter length of stay in the postanesthesia care unit (213 +/- 66 min versus 241 +/- 87 min). However, there were no significant differences between the Desflurane and the Sevoflurane groups when the MMS scores were compared preoperatively, and postoperatively at 1, 3, 6, and 24 h. Compared with the preoperative (baseline) MMS scores, the values were significantly decreased at 1 h postoperatively (27.8 +/- 1.7 versus 29.5 +/- 0.5 in the Desflurane group, and 27.4 +/- 1.7 versus 29.2 +/- 1.0 in the Sevoflurane group, respectively). However, the MMS scores returned to preoperative baseline levels within 6 h after surgery. At 1 h and 3 h after surgery, 51% and 11% (versus 57% and 9%) of patients in the Desflurane (versus Sevoflurane) Group experienced cognitive impairment. In conclusion, desflurane is associated with a faster early recovery than sevoflurane after general anesthesia in elderly patients. However, recovery of cognitive function was similar after desflurane and sevoflurane-based anesthesia. IMPLICATIONS: Desflurane was associated with a faster early recovery than sevoflurane after general anesthesia in elderly patients. However, recovery of cognitive function was similar with both volatile anesthetics.

Aged↗
PubMed2001

Comparison of long-term immunosuppression for limb transplantation using cyclosporine, tacrolimus, and mycophenolate mofetil: implications for clinical composite tissue transplantation.

This study compared the efficacy of long-term intermittent immunosuppression in preventing the rejection of a limb transplant across the strongest histocompatibility barrier in ACI --> Lewis rats using the conventional immunosuppressive agent cyclosporine-A and the newer immunosuppressive agents FK-506 (tacrolimus) and RS-61443 (mycophenolate mofetil). The recipient animals were immunosuppressed daily for 14 days postoperatively, followed by long-term intermittent, twice-weekly immunosuppression using cyclosporine 25 mg/kg, RS-61443 30 mg/kg, or FK-506 2 mg/kg. All three immunosuppressive agents were able to prolong the rejection of the skin component of a limb transplant compared with nonimmunosuppressed controls. Eight of nine animals receiving cyclosporine immunosuppression showed signs of rejection of the skin component of the limb transplant while continuing to receive long-term immunosuppression and had a mean rejection time of 61.6 days. Seven of 10 animals immunosuppressed with RS-61443 also showed signs of rejection while still receiving immunosuppression, with a mean rejection time of 43.6 days. Nine of 10 animals receiving FK-506 immunosuppression showed no signs of skin rejection, but died of bacterial pneumonia between 273 and 334 days after transplantation, with a mean rejection time of 296.1 days. There was no statistically significant difference between intermittent immunosuppression with cyclosporine and RS-61443, but FK-506 was significantly superior to both cyclosporine and RS-61443. The implication of this study is that FK-506, but not cyclosporine or RS-61443, is probably the only single immunosuppressive agent capable of preventing rejection of the skin component of a composite tissue transplant. Combination immunosuppression with FK-506 and RS-61443, therefore, may be required to allow composite tissue transplantation to become a predictable clinical reality in the future.

Animals↗
PubMed2001

Targeted disruption of the transition protein 2 gene affects sperm chromatin structure and reduces fertility in mice.

During mammalian spermiogenesis, major restructuring of chromatin takes place. In the mouse, the histones are replaced by the transition proteins, TP1 and TP2, which are in turn replaced by the protamines, P1 and P2. To investigate the role of TP2, we generated mice with a targeted deletion of its gene, Tnp2. Spermatogenesis in Tnp2 null mice was almost normal, with testis weights and epididymal sperm counts being unaffected. The only abnormality in testicular histology was a slight increase of sperm retention in stage IX to XI tubules. Epididymal sperm from Tnp2-null mice showed an increase in abnormal tail, but not head, morphology. The mice were fertile but produced small litters. In step 12 to 16 spermatid nuclei from Tnp2-null mice, there was normal displacement of histones, a compensatory translationally regulated increase in TP1 levels, and elevated levels of precursor and partially processed forms of P2. Electron microscopy revealed abnormal focal condensations of chromatin in step 11 to 13 spermatids and progressive chromatin condensation in later spermatids, but condensation was still incomplete in epididymal sperm. Compared to that of the wild type, the sperm chromatin of these mutants was more accessible to intercalating dyes and more susceptible to acid denaturation, which is believed to indicate DNA strand breaks. We conclude that TP2 is not a critical factor for shaping of the sperm nucleus, histone displacement, initiation of chromatin condensation, binding of protamines to DNA, or fertility but that it is necessary for maintaining the normal processing of P2 and, consequently, the completion of chromatin condensation.

Animals↗
PubMed2001

Computerized hemodynamic evaluation of the cerebral circulation for bypass.

This article describes details of the application of computer modeling of cerebral blood circulation. A brief review of the different computer modeling techniques and the current models used today for predicting surgical options for bypass surgery are presented. The use of phase contrast MR for estimating intracranial flow rates makes these models even more accurate. Two case studies are presented with computer simulation results with verification of predicted outcome both clinically and from actual flow of measurements.

Brain↗
PubMed2001

[Effects of vascular endothelial growth factor on adhesion molecular expression of hepatocellular carcinoma HepG].

OBJECTIVE: To study the effect of vascular endothelial growth factor (VEGF) on homotypic adhesion and E-cadherin of hepatocellular carcinoma cells. METHODS: We measured the function of homotypic adhesion with (3)H-TdR infiltration and the expression of E-cadherin with laser scanning confocal microscope. RESULTS: After 60, 90, 120min, the values (dpm/min) of (3)H-TdR infiltration in HepG(2) cells induced by 1ng/ml, 5ng/ml VEGF were 1758.67+/-289.46, 1380.03+/-328.55, 2657.43 +/- 310.31 and 3124.30+/-262.14, 2245.60+/-273.24, 2091.52+/-213.84. The values by 10ng/ml VEGF were 1232.32+/-201.04, 2337.50+/-333.04, 2236.99 +/- 237.07, which were significantly lower than those in control group (P<0.05 or 0.01). The expression of E-cadherin in hepatocellular carcinoma cells induced by 5ng/ml VEGF was 352+/-56 and much lower than that in control group (757+/-103, P<0.01). CONCLUSIONS: VEGF can decrease homotopic adhesion of hepatocellular carcinoma HepG(2) cell, which is connected with the less expression of E-cadherin in hepatocellular carcinoma HepG(2) cell.

Cadherins↗
PubMed2001

[Latent adenovirus infection in chronic obstructive pulmonary disease].

OBJECTIVE: To study latent adenovirus infection in the stable stage of chronic obstructive pulmonary disease(COPD). METHOD: The bronchial epithelial cells and alveolar macrophages from 12 patients with chronic bronchitis, 10 patients with COPD, 6 patients with asthma and 8 healthy volunteers were obtained by bronchosocpy. The adenoviral DNA was determined in the epithelial cells and macrophages. All patients were in the stable stage. The polymerase chain reaction(PCR) was used for detection of the adenoviral genome E1A. RESULTS: The E1A region of adenovirus was found in the epithelial cells of COPD and chronic bronchitis patients (27%), not found in the patients with asthma and normal volunteers. Furthermore, E1A DNA was much more commonly in the COPD patients (50%) than in the patients with chronic bronchitis (8%) (P < 0.05). CONCLUSIONS: Latent adenoviral infection was present in the stable stage of COPD and may be related to the pathogenesis of the disease.

Adenoviridae↗