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Biomedical subjects

Z Xiao

Publications and source records attributed to Z Xiao.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Construction of three transgenic vectors carrying the latent membrane protein gene of Epstein-Barr virus].

In order to produce transgenic mice carrying the latent membrane protein(LMP) gene of Epstein-Barr virus(EBV) and to study the oncogenic role of LMP gene in vivo, three different transgenic vectors carrying the LMP gene were constructed. In pBR322-MT-LMP vector, the promoter of LMP gene is the regulation region of mouse metallothionein-I gene. In pMci3-LMP shuttle vector, the promoter of LMP gene is the replication origin(oriP) of EBV. In pMV-LMP-c-myc retroviral vector, the long terminal repeat (LTR) of mouse sarcomavirus serves as the promoter of LMP gene. The characterization and usefulness of these three transgenic vectors are also discussed.

Animals↗
PubMed1999

[Changes of TF and TFPI activities in patients with hypertension or coronary atherosclerotic heart disease].

OBJECT: To investigate the changes of tissue factor (TF) and tissue factor pathway inhibitor(TFPI) activities in patients with hypertension or coronary atherosclerotic heart (CAH) disease. METHODS: TF activity was measured by two-stage assay, and TFPI activity was detected according to Sandset's method. RESULTS: Plasma TF activity in both patients with hypertension and patients with CAH disease was higher than that of normal control(P < 0.05). CONCLUSION: Hypercoagulative state may be involved in the pathogenetic processes of hypertension and CAH diseases. TF and TFPI activities have the likelihood to become the accessory diagnostic indexes for hypertension and CAH diseases.

Adult↗
PubMed1999

[Acute flare-up of senile cardiopulmonary disease and multi-system organ failure].

In this paper we report 163 cases of senile cardiopulmonary disease. Among them, 60 sustained multi-system organ failure(36.9%). Of those 60, 19 patients died(death rate 31.7%). We believe that most of the acute attacks of senile cardiopulmonary disease were induced by pneumonia. Therefore it is very important to control infection while treating respiratory-circulation failure, pulmonary encephalopathia, shock, acid-base imbalance, and other complications.

Acute Disease↗
PubMed1999

[Treatment of late thoracolumbar fracture by transpedicular decompression using "PUMC trephine" 26 cases report].

OBJECTIVE: To introduce a new operation to treat late thoracolumbar fracture cases with neurological deficit or with kyphosis. METHODS: 26 cases were treated with "PUMC trephine" (designed by professor Ye Qibin). RESULTS: The kyphosis was (29.7 +/- 14.5) degrees Cobb's angle in pre-operation and (10 +/- 11.8) degrees in post-operation (P < 0.01). The angle of correction was (19.7 +/- +9.9) degrees. The height of the anterior edge of traumatic-vertebra was (16.3 +/- 5.7) mm in pre-operation and (22.2 +/- 6.3) mm in post-operation. The corrected height was (6.5 +/- 3.2) mm. The neurological deficit also got a better recovery in 17 of 19 cases, 12 of 15 cases obtained complete cure of incontinence. 11 of 15 case had sexual function recovery after following up 1-9 years (average 5.2 years) cases. CONCLUSIONS: Using "PUMC trephine" procedure was a new, simple, safety and less-traumatic technique for treatment of late thoracolumbar fracture through posterior approach.

Adult↗
PubMed1998

Platelet activation with unfractionated heparin at therapeutic concentrations and comparisons with a low-molecular-weight heparin and with a direct thrombin inhibitor.

BACKGROUND: The growing use of heparin in acute thrombotic disorders, coupled with the availability of many new antithrombotic agents, emphasizes the need for adequate characterization of the platelet effects of the various anticoagulants. Controversial platelet effects have been reported with heparin (eg, enhanced platelet activation in vitro with high doses and no such effect in vivo at therapeutic doses). This study examined platelet receptor activation and platelet aggregation at therapeutic concentrations of unfractionated heparin (UFH), of enoxaparin, a low-molecular-weight heparin, and of argatroban, a direct thrombin inhibitor. METHODS AND RESULTS: Platelet P-selectin (CD62) and activated GP IIb/IIIa (PAC-1) expression on platelet membrane was quantified in whole blood as well as platelet aggregation in platelet-rich plasma in 43 patients with unstable angina before and during treatment with UFH or enoxaparin. Studies were also carried out in blood of seven normal volunteers after addition ex vivo of UFH (0.25 U/mL), enoxaparin (0.25 U/mL), argatroban (1 ng/mL), and normal saline. UFH in patients with unstable angina increased the percentage of circulating platelets positive to PAC-1 from 2.7+/-1.7% to 4.4+/-3.4% (P<.05) and to CD62 from 1.6+/-0.9% to 2.7+/-1.5% (P<.01). Platelets were also hyperresponsive to stimulation with ADP and with the thrombin-receptor agonist peptide. Aggregation to ADP increased from 6.8+/-4.6% to 11.2+/-7.0% and to TRAP from 5.2+/-3.5% to 11.1+/-6.0% (P<.001). The addition of UFH to blood of normal volunteers resulted also in activation of GP IIb/IIIa receptors, expression of P-selectin, and enhanced platelet aggregation. Enoxaparin had only minor effects on platelet activation in vivo and ex vivo, and argatroban, evaluated ex vivo, had no detectable effects. CONCLUSIONS: Therapeutic concentrations of UFH are associated with platelet activation.

Adenosine Diphosphate↗
PubMed1998

Atmospheric mercury deposition on Fanjing Mountain Nature Reserve, Guizhou, China.

Fanjing Mountain Nature Reserve (FMNR) is surrounded with several Hg emission sources within distances of 100-200 km. At the two sites studied, Tongren and Danzai, Hg emission and deposition fluxes, Hg concentration in the air, soil and other samples are all several hundred times higher than at other relatively clean areas. Hg accumulation in soil and moss at FMNR varies with the sampling heights. Total Hg deposition to this area has been estimated to be 115 micrograms m-2 y-1 using moss bag technique. Dry deposition was determined to be about 5.2 micrograms m-2 month-1 during March to June, corresponding to more than 50% of the total deposition.

Air Pollutants, Occupational↗
PubMed1998

Children's support for elderly parents in urban and rural China: results from a national survey.

This study examines the factors that determine adult children's financial support for elderly parents, using data from the China Survey on Support Systems for the Elderly conducted in 1992. The findings support the hypotheses of need-based transfers. In both urban and rural areas, children's financial transfers to their elderly parents are based on the parents' need, and familial support compensates for inequalities in elderly persons' access to public resources. The data also suggest that elderly support is an outcome of short- and long-term arrangements between generations. Elderly Chinese, especially those in urban areas, have short-term exchanges with their adult children, providing housing or other services and receiving financial support in return. Also, adult children's support for elderly parents may be a repayment of parental investment made in them earlier.

Journal Article↗
PubMed1998

Impaired G protein function in gallbladder muscle from progesterone-treated guinea pigs.

This study was designed to elucidate the mechanism of action of progesterone on gallbladder smooth muscle in guinea pigs. Adult male guinea pigs were treated with either progesterone (2 mg.kg-1.day-1) or saline for 7 days. Gallbladder muscle cells were isolated by enzymatic digestion with collagenase. Contractile responses to agonists were expressed as percent shortening from control cell length. [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S)-binding properties of G proteins were assessed in crude membranes of gallbladder muscle with or without cholecystokinin octapeptide (CCK-8) stimulation. Gallbladder muscle cells from progesterone-treated guinea pigs exhibited an impaired contractile response to CCK-8, GTP gamma S, or aluminum fluoride but a normal response to potassium chloride or D-myo-inositol 1,4,5-trisphosphate compared with controls. Western blot analysis of gallbladder muscle revealed the presence of Gi1-2, Gi3, Gq/11, and Gs proteins. The maximal contraction induced by CCK-8 was blocked by pertussis toxin and Gi alpha 3-specific antibodies, but not by Gi alpha 1-2 or Gq/11 alpha antibodies. CCK-8 caused a significant increase in [35S]GTP gamma S binding to Gi alpha 3, but not to Gq/11 alpha or Gi alpha 1-2. The stimulation of Gi alpha 3 binding, however, was significantly reduced in gallbladder muscle membranes from progesterone-treated guinea pigs compared with that in control animals. In conclusion, progesterone might cause gallbladder hypomotility by downregulating Gi3 proteins.

Aluminum Compounds↗
PubMed1998

Signal transduction pathways mediating CCK-induced gallbladder muscle contraction.

The signal transduction that mediates CCK-induced contraction of gallbladder muscle was investigated in the cat. Contraction was measured by scanning micrometry in single muscle cells isolated enzymatically with collagenase. Production of D-myo-inositol 1,4, 5-trisphosphate (IP3) and sn-1,2-diacylglycerol (DAG) was quantitated using HPLC and TLC, respectively. Protein kinase C (PKC) activity was determined by measuring the phosphorylation of a specific substrate peptide from myelin basic protein, Ac-MBP-(4-14). CCK-induced contraction was blocked by incubation in strontium medium, pertussis toxin (PTx), and antibodies against Gialpha3 or betagamma-subunits but was not blocked by Ca2+-free medium or by antibodies against Gq/11alpha, Gialpha1-2, or Goalpha. The contraction induced by CCK was inhibited by the phospholipase C (PLC) inhibitor U-73122, anti-PLC-beta3 antibody, and the IP3 receptor antagonist heparin but was not inhibited by the the phospholipase D inhibitor propranolol or antibodies against PLC-beta1 or PLC-beta2. Western blot analysis of gallbladder muscle revealed the presence of PLC-beta2 and PLC-beta3 but not PLC-beta1. CCK caused a 94% increase in IP3 generation and an 86% increase in DAG generation. A low dose of CCK caused PKC translocation, and CCK-induced contraction was blocked by the PKC inhibitor H-7. A high dose of CCK, however, caused no PKC translocation, and its contraction was blocked by the calmodulin antagonist CGS9343B. In conclusion, CCK contracts cat gallbladder muscle by stimulating PTx-sensitive Gi 3 protein coupled with PLC-beta3, producing IP3 and DAG. Low doses activate PKC, whereas high doses activate calmodulin.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1998

[Clinical of 50 cases of aged patients with pneumonia caused by gram-negative bacteria].

The diagnosis and treatment of 50 cases of aged patients with pneumonia caused by gram-negative G-bacteria (from Feb. 1993 to Aug. 1997) were analyzed. Before the results of drug sensitive tests were reported, aminoglycosides plus broad-spectrum semisynthetic penicillin or first generation cephalosporin could improve the curative effect in patients with good renal function. Bacterial culture and drug sensitive tests were crucial for choosing the proper antibiotics.

Aged↗
PubMed1998

[Diagnostic value of p53 protein examination in lung cancer through preoperative fibro-optic bronchoscope brushing and biospy].

OBJECTIVE: To study the expression of p53 protein in lung cancer and benign pulmonary diseases through preoperative fibro-optic bronchoscope brushing and biospy as an approach to early diagnosis of lung cancer and to explore correlation between the expression of the gene product and metastatic involvement of hilar or mediastial lymph nodes. METHODS: Using a monoclonal antibody against p53, the expression of p53 protein was determined by immunocyto-histochemical techniques. RESULTS: Positive staining of p53 protein of cells obtained form bronchoscopic brushing and biospy was 33.3% (12/36) and 47.2% (17/36) respectively in lung cancer patients. There was 61.1% (22/36) positive staining of cells harvested by brushing plus biospy in lung cancer. No correlation between p53 protein expression and cell differentiation, histologic type or pTNM staging. No p53 expression was observed in benign pulmonary diseases. CONCLUSION: p53 protein expression in cells collected from bronchoscopic brushing and biopsy may be useful in the diagnosis of lung cancer.

Adenocarcinoma↗
PubMed1998

[Cloning and expression of subunit genes of pertussis toxin and its immunological evaluation].

OBJECTIVE: To clone the gene encoding pertussis toxin (PT) from Bordetella Pertussis CS strain and five genes encoding subunits of PT, to investigate the possibility of expressing the genes encoding for mature methionyl subunits of PT in insect cell and to evaluate the immunological characteristics of recombinant subunits. METHODS: The genes encoding for PT and its subunits were cloned by PCR and confirmed by restriction enzyme digestion and Southern blot. Using recombinant baculovirus technology, the recombinant subunits were expressed in Sf9 insect cells and analyzed by immunofluorescence assay. The immunological properties of recombinant subunits were analyzed by ELISA. RESULTS: The genes encoding for PT and its subunits were cloned and expressed in Sf9 cells. The level of specific antibodies against nature PT induced by five recombinant subunits polymerized was higher than that unpolymerized and polymerized by four recombinant subunits (without S1) in mice. The results indicate that PT subunits had weak ability to induce specific antibodies against PT, and also anti-nature PT sera had poor recognition to PT subunits. CONCLUSION: The ability of PT to induce specific antibody is conformation dependent of intact PT, and antibody induction domains are located dominantly in S1 subunit of intact PT.

Animals↗
PubMed1998

Mechanism of gallbladder relaxation in the cat: role of norepinephrine.

We investigated the mechanisms of neurally mediated relaxation of cat gallbladder muscle. Muscle strips from the gallbladder corpus placed in the muscle bath with oxygenated Krebs' solution developed spontaneous active tension. Tension was measured with isometric force transducers, and muscle relaxation was expressed as percent decrease of active basal tension. Electrical field stimulation (EFS) evoked a tetrodotoxin-sensitive and hexamethonium-insensitive frequency-dependent relaxation with a maximal relaxation at 20 Hz. Gallbladder muscle strips also relaxed in response to increasing concentrations of vasoactive intestinal peptide (VIP), isoproterenol and, after pretreatment with phentolamine, norepinephrine. Nitric oxide synthase inhibitors N omega-nitro-L-arginine and N omega-nitro-L-arginine methyl ester at a concentration of 100 microM, which blocked EFS-induced relaxation in the lower esophageal sphincter, had no significant effect on EFS-induced gallbladder muscle relaxation. The VIP antagonists VIP10-28 and [4Cl-D-Phe6,Leu17]VIP at a concentration of 10 microM that blocked exogenous VIP-induced gallbladder relaxation also had no effect on the relaxation caused by EFS. In contrast, either propranolol or guanethidine at concentrations of > or = 1 microM significantly reduced EFS-evoked gallbladder relaxation (P < .01, analysis of variance). It is concluded that norepinephrine utilizing beta adrenergic receptors mediates EFS-stimulating postganglionic intramural neurons in the cat gallbladder.

Animals↗
PubMed1998

Biodistribution of Photofrin II and 5-aminolevulinic acid-induced protoporphyrin IX in normal rat bladder and bladder tumor models: implications for photodynamic therapy.

Photodynamic therapy (PDT) has been considered as a potential therapy for superficial bladder carcinomas. Cutaneous photosensitivity and reduction of bladder capacity are the two well-known complications following systemic administration of the commonly used photosensitizer, Photofrin II (PII). The objective of the present study was to evaluate whether intravesical (i.b.) instillation of photosensitizers for PDT of bladder cancer might be a more suitable treatment method. Female Fischer rats were utilized to develop orthotopic and heterotopic bladder tumor models. Rats bearing orthotopic bladder tumors were treated either intravesically or intravenously with graded doses of 5-aminolevulinic acid (ALA) or PII. Normal rats received the same doses of ALA or PII. As well, rats bearing heterotopic tumor were studied for comparison. The biodistribution times (times allowed for tissue uptake and bioconversion following drug administration) were 2, 4 or 6 h. Porphyrin fluorescence intensities within tumor, urothelium, submucosa, bladder muscularis and abdominal muscle were quantitated by confocal laser scanning microscopy. Following intravenous (i.v.) injection of ALA, tumor protoporphyrin IX (PpIX) levels peaked at 4 h and diminished by 6 h. The PpIX ratios of tumor-to-bladder mucosa, submucosa and muscle layers were 3:1, 5:1 and 8:1, respectively, 4 h following 1000 mg/kg ALA injection. After ALA instillation, the optimal biodistribution time appeared to be 4 h. Bladder instillation provided comparable tumor labeling with the i.v. route, but lost selectivity of PpIX accumulation between tumor and normal urothelium. The PpIX ratio of tumor-to-bladder muscularis was 5:1. After i.b. instillation of PII, porphyrin fluorescence was detected only within tumor and urothelium, while porphyrin fluorescence was mainly located in bladder submucosa following i.v. injection. Intravesical administration of ALA or PII might be feasible for PDT of superficial bladder cancers.

Aminolevulinic Acid↗
PubMed1997

Dynamic distribution of chemoattractant receptors in living cells during chemotaxis and persistent stimulation.

While the localization of chemoattractant receptors on randomly oriented cells has been previously studied by immunohistochemistry, the instantaneous distribution of receptors on living cells undergoing directed migration has not been determined. To do this, we replaced cAR1, the primary cAMP receptor of Dictyostelium, with a cAR1-green fluorescence protein fusion construct. We found that this chimeric protein is functionally indistinguishable from wild-type cAR1. By time-lapse imaging of single cells, we observed that the receptors remained evenly distributed on the cell surface and all of its projections during chemotaxis involving turns and reversals of polarity directed by repositioning of a chemoattractant-filled micropipet. Thus, cell polarization cannot result from a gradient-induced asymmetric distribution of chemoattractant receptors. Some newly extended pseudopods at migration fronts showed a transient drop in fluorescence signals, suggesting that the flow of receptors into these zones may slightly lag behind the protrusion process. Challenge with a uniform increase in chemoattractant, sufficient to cause a dramatic decrease in the affinity of surface binding sites and cell desensitization, also did not significantly alter the distribution profile. Hence, the induced reduction in binding activity and cellular sensitivity cannot be due to receptor relocalization. The chimeric receptors were able to "cap" rapidly during treatment with Con A, suggesting that they are mobile in the plane of the cell membrane. This capping was not influenced by pretreatment with chemoattractant.

Animals↗
PubMed1997

Shear stress induction of the endothelial nitric oxide synthase gene is calcium-dependent but not calcium-activated.

Arterial levels of shear stress (25 dynes/cm2) can elevate constitutive endothelial nitric oxide synthase (eNOS) gene expression in cultured endothelial cells (Ranjan et al., 1995). By PhosphorImaging of Northern blots, we report that the eNOS/glyceraldehyde 3-phosphate dehydrogenase (GAPDH) messenger RNA (mRNA) ratio in bovine aortic endothelial cells (BAEC) increased by 4.8- and 7.95-fold after 6-hr shear stress exposure of 4 and 25 dynes/cm2, respectively. Incubation of BAEC with dexamethasone (1 microM) had no effect on shear stress induction of eNOS mRNA. Buffering of intracellular calcium in BAEC with bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)-ester (BAPTA/AM) reduced shear stress induction of eNOS mRNA by 70%. Yet, stimulation of BAEC with ionomycin (0.1-1.0 microM) for 6-24 hr to elevate intracellular calcium had no effect on eNOS mRNA. These studies indicated that the shear stress induction of eNOS mRNA was a calcium-dependent, but not calcium-activated, process. Shear stress was a very potent and rapid inducer of the eNOS mRNA, which could not be mimicked with phorbol myristrate acetate or endotoxin. Inhibition of tyrosine kinases with genistein (10 microM) or tyrphostin B46 (10 microM) or inhibition of G-protein signaling with guanosine 5'-O-(2-thiodiphosphate) (GDP-betaS) (600 microM, 6-hr preincubation) did not block the shear stress elevation of eNOS mRNA.

Animals↗