Search PubMed⌕ Search

Biomedical subjects

Z Zhou

Publications and source records attributed to Z Zhou.

At least 397 records · Page 22Linked to original sources
PubMed1996

[An experimental study of cytology in the aqueous humor of rabbit eyes after intraocular lens implantation].

OBJECTIVE: The study was designed to count the number of white blood cells and observe their subset distribution in the aqueous humor after extracapsular lens extraction and intraocular lens (IOL) implantation in capsular bag in rabbits and to discuss the mechanism of postoperative intraocular inflammatory response. METHODS: 27 adult pigmented rabbits were divided into three groups: (1) The IOL was placed in the capsular bag after extracapsular lens extraction; (2) The extracapsular lens extraction; and (3) The control group without any surgical intervention. Aqueous humor samples were aspirated on the postoperative 1, 3, 7 and 14 days, and the total number of white blood cells in the aqueous humor and their subset distribution were counted. The data were analyzed by using analysis of variance of SAS software. RESULTS: There was a significantly higher number of inflammatory cells in the IOL implanted eyes than that in the eyes with only extracapsular lens extraction. CONCLUSIONS: In the early postoperative stage, there was a marked increase in the number of white blood cells and polymorphonuclear leukocytes in the IOL group, that is probably related to the mechanical ocular tissue damage and the breakdown of the blood-aqueous barrier induced by the operative procedures. There were a significant increase in the macrophages, eosinophiles, and lymphocytes in the IOL group, that suggests that an active immune response exist in the anterior ocular inflammation after IOL implantation.

Animals↗
PubMed1996

[An experimental study of tumor necrosis factor (TNF) and interleukin-1 (IL-1) in aqueous humor after intraocular lens implantation].

OBJECTIVE: The tumor necrosis factor (TNF) and interleukin-1 (IL-1) levels in aqueous humor after intraocular lens (IOL) implantation were studied in rabbit eyes and their effects on post-operative anterior ocular inflammation were discussed. METHODS: 27 adult pigmented rabbits were divided into three groups: (1) Lens extraction and intraocular lens (IOL) implantation in the capsular bag. (2) Simple extracapsular lens extraction, and (3) normal control group without surgical intervention. Aqueous humor samples were aspirated on days 1, 3, 7 and 14 postoperatively. A modified double-antibody indirect sandwich ELISA was used to detect for the presence of TNF. MTT colorimetry was used to detect for the presence of IL-1. The data were analysed statistically. RESULTS: TNF and IL-1 levels in the aqueous humor were significantly higher (P < 0.05) at 1, 3, 7, and 14 days postoperatively in IOL implanted group than that in the control group, and TNF levels in aqueous humor at 3, 7 and 14 days postoperatively and IL-1 levels at 1 and 3 days postoperatively were significantly higher (P < 0.05) in IOL implanted group than that in simple extracapsular lens extraction group (P < 0.05). In the postoperative 7-14 days, the TNF and in the 3 to 14 days the IL-1 in the aqueous humor reached their maximum levels in IOL implantation group. CONCLUSIONS: It is reasonable to consider that the increases of TNF and IL-1 levels may play critical roles in the anterior ocular inflammation response after IOL implantation.

Animals↗
PubMed1996

[The effect of Gynostemma pentaphyllum mak (GP) on carcinogenesis of the golden hamster cheek pouch induced by DMBA].

The purpose of the study is to examine the effect of GP during carcinogenesis of the golden hamster cheek pouches induced by DMBA. The results indicated that epithelial olysplasia and carcinoma in situ appeared respectively at 3 and 6 weeks. The formation of carcinoma was detected as early as 4 weeks which is earlier than that of former reports. The experiment proves that GP has positive anticarcinogenic function. Long-term observation in those the DMBA has been applied for 3 weeks found that epithelial dysplasia could reverse when GP was given. A compound prescription is better than GP alone.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

[Experimental study of adoptive immunotherapy for adenoid cystic carcinoma of the salivary gland].

To study adoptive immunotherapy for adenoid cystic carcinoma of the salivary gland, we evaluate the influence of TNF-alpha or IFN-gamma on the activity of LAK cells when they acted at different stages of LAK cells killing target cells. The results in vitro experiment showed that ACC-2 was susceptible to LAK cytotoxicity. Both TNF-alpha and IFN-gamma could be an enhancer to augment IL-2-induced LAK cytotoxity against ACC-2, TNF-alpha should be used to induce LAK cells, but IFN-gamma is suitable to pretreat target cells ACC-2.

Carcinoma, Adenoid Cystic↗
PubMed1996

[Influence of temperature on the chemical constituents and pharmacological effects of semen Cassiae].

The influence of temperature on the chemical constituents and pharmacological effects of seeds of Cassia tora was examined. As the baking temperature was raised, the contents of free chrysophanol increased. The contents of antihepatotoxic constituents in the samples baked at different temperatures were compared. They decreased as the temperature rose. The pharmacological results basically accorded with the contents of the constituents.

Alanine Transaminase↗
PubMed1995

Crystal structure of human Charcot-Leyden crystal protein, an eosinophil lysophospholipase, identifies it as a new member of the carbohydrate-binding family of galectins.

BACKGROUND: The Charcot-Leyden crystal (CLC) protein is a major autocrystallizing constituent of human eosinophils and basophils, comprising approximately 10% of the total cellular protein in these granulocytes. Identification of the distinctive hexagonal bipyramidal crystals of CLC protein in body fluids and secretions has long been considered a hallmark of eosinophil-associated allergic inflammation. Although CLC protein possesses lysophospholipase activity, its role(s) in eosinophil or basophil function or associated inflammatory responses has remained speculative. RESULTS: The crystal structure of the CLC protein has been determined at 1.8 A resolution using X-ray crystallography. The overall structural fold of CLC protein is highly similar to that of galectins -1 and -2, members of an animal lectin family formerly classified as S-type or S-Lac (soluble lactose-binding) lectins. This is the first structure of an eosinophil protein to be determined and the highest resolution structure so far determined for any member of the galectin family. CONCLUSIONS: The CLC protein structure possesses a carbohydrate-recognition domain comprising most, but not all, of the carbohydrate-binding residues that are conserved among the galectins. The protein exhibits specific (albeit weak) carbohydrate-binding activity for simple saccharides including N-acetyl-D-glucosamine and lactose. Despite CLC protein having no significant sequence or structural similarities to other lysophospholipase catalytic triad has also been identified within the CLC structure, making it a unique dual-function polypeptide. These structural findings suggest a potential intracellular and/or extracellular role(s) for the galectin-associated activities of CLC protein in eosinophil and basophil function in allergic diseases and inflammation.

Acute Disease↗
PubMed1995

A controlled study of adenoviral-vector-mediated gene transfer in the nasal epithelium of patients with cystic fibrosis.

BACKGROUND: Cystic fibrosis is a monogenic disease that deranges multiple systems of ion transport in the airways, culminating in chronic infection and destruction of the lung. The introduction of a normal copy of the cystic fibrosis transmembrane conductance regulator (CFTR) gene into the airway epithelium through gene transfer is an attractive approach to correcting the underlying defects in patients with cystic fibrosis. We tested the feasibility of gene therapy using adenoviral vectors in the nasal epithelium of such patients. METHODS: An adenoviral vector containing the normal CFTR complementary DNA in four logarithmically increasing doses (estimated multiplicity of infection, 1, 10, 100, and 1000), or vehicle alone, was administered in a randomized, blinded fashion to the nasal epithelium of 12 patients with cystic fibrosis. Gene transfer was quantitated by molecular techniques that detected the expression of CFTR messenger RNA and by functional measurements of transepithelial potential differences (PDs) to assess abnormalities of ion transport specific to cystic fibrosis. The safety of this treatment was monitored by nasal lavage and biopsy to assess inflammation and vector replication. RESULTS: The adenoviral vector was detected in nasal-lavage fluid by culture, the polymerase chain reaction (PCR), or both in a dose-dependent fashion for up to eight days after vector administration. There was molecular evidence of gene transfer by reverse-transcriptase PCR assays or in situ hybridization in five of six patients treated at the two highest doses. However, the percentage of epithelial cells transfected by the vector was very low (< 1 percent), and measurement of PD across the epithelium revealed no significant restoration of chloride transport or normalization of sodium transport. At the lower doses of vector, there were no toxic effects. However, at the highest dose there was mucosal inflammation in two of three patients. CONCLUSIONS: In patients with cystic fibrosis, adenoviral-vector-mediated transfer of the CFTR gene did not correct functional defects in nasal epithelium, and local inflammatory responses limited the dose of adenovirus that could be administered to overcome the inefficiency of gene transfer.

Adenoviruses, Human↗
PubMed1995

Amperometric detection of stimulus-induced quantal release of catecholamines from cultured superior cervical ganglion neurons.

Amperometry has been used for real-time electrochemical detection of the quantal release of catecholamines and indolamines from secretory granules in chromaffin and mast cells. Using improved-sensitivity carbon fiber electrodes, we now report the detection of quantal catecholamine release at the surface of somas of neonatal superior cervical ganglion neurons that are studded with axon varicosities containing synaptic vesicles. Local application of a bath solution containing high K+ or black widow spider venom, each of which greatly enhances spontaneous quantal release of transmitter at synapses, evoked barrages of small-amplitude (2-20 pA), short-duration (0.5-2 ms) amperometric quantal "spikes". The median spike charge was calculated as 11.3 fC. This figure corresponds to 3.5 x 10(4) catecholamine molecules per quantum of release, or approximately 1% that evoked by the discharge of the contents of a chromaffin granule.

Animals↗
PubMed1995

Fractional calcium currents through recombinant GluR channels of the NMDA, AMPA and kainate receptor subtypes.

1. Simultaneous fluorescence and whole-cell current measurements using the calcium indicator dye fura-2 were made in HEK 293 cells expressing recombinant glutamate receptor (GluR) channels, and fractional Ca2+ currents (the proportion of whole-cell current carried by Ca2+; Pf) were determined. 2. Cells expressing N-methyl-D-aspartate receptor (NMDAR) channels showed glutamate activated Ca2+ inflow in the voltage range -60 to 40 mV in normal extracellular solution. Ca2+ inflow decreased in a voltage-dependent manner at membrane potentials more negative than -30 mV due to Mg2+ block. Voltage dependence of block at negative potentials was stronger in cells expressing the NR1-NR2A as compared with cells expressing NR1-NR2C subunits. 3. Fractional Ca2+ currents through NMDARs were independent of extracellular Mg2+ and varied between 8.2% (NR1-NR2C subunits) and 11% (NR1-NR2A subunits) in normal extracellular solution (1.8 mM Ca2+) at -60 mV membrane potential. Pf values increased with increasing [Ca2+]o in the range of 0.5-10mM [Ca2+]o in a saturating fashion. 4. In cells expressing alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor (AMPAR) subunits which were unedited at the Q/R site of the putative transmembrane segment TM2 (Q-form), or in cells coexpressing unedited and edited subunits (R-form), the glutamate-evoked Ca2+ inflow increased from 20 to -80 mV in an almost linear way. 5. Fractional Ca2+ currents through AMPAR channels depended on subunit composition. Pf values of Q-form homomeric channels at -60 mV and 1.8 mM [Ca2+]o were between 3.2 and 3.9%. They were slightly voltage dependent and increased with [Ca2+]o in the range 1.8-10mM. Pf values in cells co-expressing Q- and R-form subunits were almost one order of magnitude smaller (0.54%). 6. Relative concentrations of Q-form and R-form GluR-B subunit-specific cDNAs used for cell transfection determined the expression of functionally different heteromeric AMPARS. Pf decreased with increasing relative concentration of R-form encoding CDNAs from 3.4 to 1.4%, demonstrating that editing of the Q/R site of GluR-B subunits decreases Ca2+ inflow through heteromeric AMPARs. 7. Cells expressing the GluR-6 subunit of the kainate receptor (KAR) family were characterized by Pf values which depended on the editing in the TM1 and TM2 segments. Pf values were largest for the Q-form (1.55-2.0%) and lowest for R-form channels (< 0.2%), suggesting that Q/R site editing also decreases Ca2+ inflow through KAR channels. Cells co-expressing both subunit forms showed an intermediate value (0.58%).(ABSTRACT TRUNCATED AT 400 WORDS)

Calcium Channel Agonists↗
PubMed1995

Electrostatic effects of surface acidic amino acid residues on the oxidation-reduction potentials of the flavodoxin from Desulfovibrio vulgaris (Hildenborough).

The flavodoxin from Desulfovibrio vulgaris (Hildenborough) is a member of a family of small, acidic proteins that contain a single noncovalently bound flavin mononucleotide (FMN) cofactor. These proteins function as low-potential one-electron transferases in bacteria. A distinguishing feature of these flavoproteins is the dramatic decrease in the midpoint potential of the semiquinone/hydroquinone couple of the FMN upon binding to the apoprotein (-172 mV for FMN free in solution versus -443 mV when bound), a perturbation thought to be essential for physiological function. The structural basis of this phenomenon is not yet thoroughly understood. In this study, the contribution of six acidic residues (Asp62, Asp63, Glu66, Asp95, Glu99, and Asp106) to the perturbation of the redox properties of the cofactor has been investigated. These residues are clustered about the FMN binding site within 13 A of the N(1) atom of the cofactor. Using oligonucleotide-directed mutagenesis, these residues were neutralized in various combinations through the substitution of asparagine for aspartate and glutamine for glutamate. Seventeen mutant flavodoxins were generated in which one to all six acidic residues were systematically neutralized, often in various spatial configurations. There was no obvious correlation between the midpoint potentials for the oxidized/semiquinone couple and general electrostatic environment, although some differences were noted. However, the midpoint potential for the semiquinone/hydroquinone couple for each of the mutants was less negative than that of the wild type. These increases are strongly correlated with the number of acid to amide substitutions, with an average contribution of about 15 mV per substitution. Collectively, the unfavorable electrostatic environment provided by these acidic residues accounts for approximately one-third of the large midpoint potential shift for the semiquinone/hydroquinone couple that typifies the flavodoxin family, apparently through the destabilization of the flavin hydroquinone anion.

Amino Acids, Dicarboxylic↗
PubMed1995

Action potential-induced quantal secretion of catecholamines from rat adrenal chromaffin cells.

Using single rat adrenal chromaffin cells, we examined the coupling of action potential activity to quantal release of catecholamines by combining perforated patch current-clamp recording with electrochemical microcarbon fiber amperometry. Chromaffin cells display steeper dependence of quantal release on action potential frequency than many nerve terminals, as well as more desynchronized release following an action potential. Also in contrast to neurons, in chromaffin cells, a major chemical secretagogue (acetylcholine) triggers potent quantal release even in the absence of electrical activity. These findings are consistent with an hypothesis that a major component of exocytosis from chromaffin cells involves diffusion of Ca2+ to secretion sites which are less well co-localized with Ca2+ channels than those in nerve terminals.

Action Potentials↗
PubMed1995

Functional characterization of the cis-regulatory elements of the rat ribophorin I gene.

The ribophorin I gene encodes a rough endoplasmic reticulum (RER) specific membrane protein which is a subunit of the oligosaccharyltransferase. To establish the functional activity of its promoter region we have performed transient gene transcription experiments employing plasmid constructs that contain 5' flanking regions of the ribophorin I gene cloned upstream of the CAT reporter gene. Among the restriction fragments obtained from the 1.3-kilobase 5' flanking region, a proximal fragment (-42 to +24) containing two GC-rich elements was required for basic promoter activity, while a fragment (-364 to +24) encoding an additional GC-box and an octamer like motif at -233 conferred the maximal promoter activity. In order to investigate the functionality of an octomer-like sequence co-transfection experiments were performed with Oct-2 cDNA and the CAT reporter gene containing the ribophorin I fragment (-364 to +24). A 3-4-fold increase in the transcriptional activity was observed with this construct. In addition, gel shift experiments showed Oct-2 binding to this construct. These results indicate that Oct-2 is most likely involved in the regulation of the ribophorin I gene transcription. We suggest that the GC-rich elements are necessary for constitutive ribophorin I expression while octamer motif binding proteins function synergistically with the GC-rich element binding proteins to increase the expression of the ribophorin I gene during the proliferation of RER.

Animals↗
PubMed1995

DNA polymerase epsilon links the DNA replication machinery to the S phase checkpoint.

Inhibition of DNA synthesis induces transcription of DNA damage-inducible genes and prevents mitotic entry through the action of the S phase checkpoint. We have isolated a mutant, dun2, defective for both of these responses. DUN2 is identical to POL2, encoding DNA polymerase epsilon (pol epsilon). Unlike sad1 mutants defective for multiple cell cycle checkpoints, pol2 mutants are defective only for the S phase checkpoint and the activation of DUN1 kinase necessary for the transcriptional response to damage. Interallelic complementation and mutation analysis indicate that pol epsilon contains two separable essential domains, an N-terminal polymerase domain and a C-terminal checkpoint domain unique to epsilon polymerases. We propose that DNA pol epsilon acts as a sensor of DNA replication that coordinates the transcriptional and cell cycle responses to replication blocks.

Alleles↗
PubMed1995

Estrogen and progesterone receptors in malignant mixed mesodermal tumors of the ovary.

Malignant mixed mesodermal tumors of the ovary occur in less than 1% of cases of ovarian cancer. They have a dismal prognosis and the most effective type of therapy is still not known. All cases of malignant mixed mesodermal tumor of the ovary between January 1, 1985 and May 1, 1994 operated on by the gynecologic oncology service are the subject of this report. Data were obtained from the hospital and office records of the patients. Nine patients who had their primary surgery by the gynecologic oncology service were found to have the diagnosis of malignant mixed mesodermal tumor of the ovary. Homologous tumors were found in five patients and heterologous tumors in four. Homologous tumors (mean survival 15.2 months) showed a better survival than heterologous tumors (mean survival 6.5 months; P = 0.001). An elevated estrogen receptor status was shown to correspond to longer survival (P < 0.0001). Six specimens were considered to be estrogen receptor positive and three were receptor negative. The mean survival in those patients who had a positive estrogen receptor status, 13.7 months, with a median of 7.5 months was significantly higher than those who were not positive, 6.7 months (P = 0.019) with a median of 6.25 months. All specimens were progesterone receptor negative. Malignant mixed mesodermal tumors of the ovary have a dismal prognosis, no effective therapy, and controversial prognostic indicators. Increasing estrogen receptor status appeared to correlate with longer mean survival. Larger, multi-institutional studies need to be done to determine the overall significance of these findings.

Female↗
PubMed1995

Characterization of human homologue of 4-1BB and its ligand.

The human homologue of 4-1BB (H4-1BB) cDNA was isolated from PMA plus ionomycin-treated human peripheral T-cell cDNA libraries. The amino acid sequence deduced from the nucleotide sequence showed that the protein is composed of 255 amino acids with 2 potential N-linked glycosylation sites. The molecular weight of its protein backbone is calculated to be 27 kDa. The H4-1BB contains features such as signal sequence and transmembrane domain, indicating that it is a receptor protein. This protein showed 60% identity of amino acid sequence to mouse 4-1BB. In the cytoplasmic domain there are 5 regions of amino acid sequences conserved from mouse to human, indicating that these residues might be important in the 4-1BB function. H4-1BB mRNA was detected in unstimulated peripheral blood T cells and was inducible in T-cell lines such as Jurkat and CEM. H4-1BB-AP, a fusion protein between the H4-1BB extracellular domain and alkaline phosphatase, was used to identify the ligand for the H4-1BB. Although the H4-1BB ligand was detected in both T and B cells of human peripheral blood, the ligand was preferentially expressed in primary B cells and B-cell lines. Daudi, a B-cell lymphoma, was one of the B-cell lines that carried a higher number of ligands. Scatchard analysis showed that the Kd = 1.4 x 10(9) M and the number of ligands in Daudi cell was 4.2 x 10(3).

3T3 Cells↗
PubMed1995

Myocardial stunning: a therapeutic conundrum.

Dobutamine and pyruvate are two inotropic agents with different mechanisms of action. Although both agents alter postischemic myocardial dysfunction, their potential metabolic effects in the setting of in vivo myocardial stunning have not been addressed. In this study, the effects of dobutamine and pyruvate on systolic wall thickening, myocardial phosphorylation potential index, interstitial fluid adenosine level, and myocardial oxygen consumption in in vivo stunned porcine myocardium were assessed. Stunning was induced with a 10-minute occlusion of the left anterior descending coronary artery. After 30 minutes of reperfusion, pigs were treated with either intravenous dobutamine (10 micrograms/kg per minute) or intracoronary pyruvate (1 ml/min, 150 mmol/L solution, pH 7.4). Infusion of both agents resulted in a marked improvement in regional systolic wall thickening. The dobutamine effect, however, produced a marked increase in myocardial oxygen consumption and was associated with an increase in interstitial adenosine caused by myocardial de-energization, because the myocardial phosphorylation potential index ratio decreased from 0.17 +/- 0.02 to 0.09 +/- 0.02 (p < 0.05). In contrast, pyruvate enhanced myocardial energy status, because the myocardial phosphorylation potential index ratio increased from 0.20 +/- 0.03 to 0.55 +/- 0.08 (p < 0.01). These experimental findings suggest that under certain circumstances the use of beta-receptor agonists to treat myocardial stunning may be suboptimal, if not undesirable. Further investigation is warranted to determine the optimum therapy for the stunned heart.

Adenosine↗
PubMed1995

Immunologic effects of low-dose polyethylene glycol-conjugated recombinant human interleukin-2 in common variable immunodeficiency.

Children or adults with the primary immunodeficiency disease, common variable immunodeficiency (CVI), have abnormally low levels of at least two of the three serum Ig isotypes. Although there appear to be intrinsic B cell defects, many have poor T cell proliferation and deficient secretion of IL-2, IL-4, IL-5 interferon-gamma, and B cell differentiation factor. Because the addition of various T cell factors can enhance Ig secretion in vitro in CVI, we have hypothesized that the B cells in this disease may be defective because they lack appropriate investigating the in vivo effects of recombinant IL-2 using a new biologic, polyethylene glycol-conjugated recombinant IL-2 (PEG-IL-2). In these studies, CVI patients were treated with weekly subcutaneous injections of PEG-IL-2. After 12 weeks, each patient had enhanced T cell proliferation, normal IL-2 production, boosted BCDF secretion, and B cells responsive to differentiation signals. During PEG-IL-2 treatment, four of five patients produced detectable serum antibody to keyhole limpet hemocyanin. These data suggest that CVI, which has the phenotype of B cell deficiency, may be caused by a lack of appropriate T cell signals for B cell maturation.

Adolescent↗