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Biomedical subjects

Z Cao

Publications and source records attributed to Z Cao.

At least 235 records · Page 13Linked to original sources
PubMed1992

Role of CAAT-enhancer binding protein isoforms in the cytokine regulation of acute-phase plasma protein genes.

Rat hepatic cells respond to interleukin (IL) -1, IL-6, and dexamethasone treatment by increasing the transcription rate of acute-phase plasma protein genes. The same conditions lead to changes in the expression of CAAT-enhancer binding protein (C/EBP) isoforms which are specific to the hepatic cell line. To identify the relationship between C/EBP isoforms and acute-phase protein gene activation, the hormone-specific expression of C/EBP alpha, beta, and delta was determined in H-35 and HTC cells and was compared to acute-phase liver. C/EBP beta was found to be the principal isoform in hepatoma cells and to be strongly stimulated by cytokines and dexamethasone in H-35 cells. Transactivating functions were observed for all three C/EBP isoforms by cotransfection of CAT gene reporter constructs containing cytokine and glucocorticoid response elements of acute-phase protein genes and expression plasmids for mouse C/EBP alpha, beta, and delta into rat and human hepatoma cells. The degree of C/EBP-mediated transactivation was, however, extremely variable among the different regulatory elements. Transcription run-on reactions with nuclei from transiently transfected H-35 cells indicated that cotransfected C/EBP beta increases basal expression of reporter gene constructs as well as the dexamethasone-mediated stimulation of constructs containing the glucocorticoid response elements of the rat alpha 1-acid glycoprotein gene, but did not accelerate or enhance hormone-dependent transcription activation of reporter gene plasmids containing the IL-6 regulatory element of the beta-fibrinogen gene. Activation of the reporter gene constructs appeared to be temporally and quantitatively correlated with the amount of nuclear C/EBP as determined by two-dimensional Western and Southwestern blot analyses.

Acute-Phase Proteins↗
PubMed1992

The role of GABAB receptor activation in absence seizures of lethargic (lh/lh) mice.

Lethargic (lh/lh) mice, which function as an animal model of absence seizures, have spontaneous seizures that have behavioral and electrographic features and anticonvulsant sensitivity similar to those of human absence seizures. Antagonists of the gamma-aminobutyric acidB (GABAB) receptor suppressed these seizures in lethargic mice, whereas agonists of GABAB receptors exacerbated them. Furthermore, GABAB receptor binding and synaptically evoked GABAB receptor-mediated inhibition of N-methyl-D-aspartate responses were selectively increased in lh/lh mice. Therefore, enhanced GABAB receptor-mediated synaptic responses may underlie absence seizures in lh/lh mice, and GABAB receptor antagonists hold promise as anticonvulsants for absence seizures.

Animals↗
PubMed1992

Calcium-regulated phosphorylation within the leucine zipper of C/EBP beta.

Alterations in intracellular calcium levels activate several signal transduction pathways resulting in distinct patterns of gene expression. Here, a pathway for calcium-mediated signals is demonstrated that involves C/EBP beta, a member of the bZip family of transcription factors. In pituitary cells C/EBP beta was phosphorylated in response to increased intracellular calcium concentrations as a consequence of the activation of a calcium-calmodulin-dependent protein kinase. Phosphorylation of serine at position 276 within the leucine zipper of C/EBP beta appeared to confer calcium-regulated transcriptional stimulation of a promoter that contained binding sites for C/EBP beta.

Amino Acid Sequence↗
PubMed1992

[Study of the estrogen receptor and progesterone receptor in human cervical carcinoma].

Three hundred and twelve different cervical specimens have been tested for estrogen (ER) and progesterone receptor (PR) content with dextran-coated charcoal method (DCC). The results showed that the concentrations of ER and PR in normal cervical tissues were higher than those in malignant cervical tissues, and that the percentage of positive scores for ER and PR in cervical squamous epithelial tissues were higher than that in malignant cervical tissues. That the variances of ER and PR in cervical malignant tumors were not parallel suggested that the production or/and the mechanism of receptor action might be impaired. The percentage of positive scores for ER was not correlated with the clinical stages whereas that of PR was inversely proportional to clinical stages. That some patient with cervical cancer had high level of PR and had both ER and PR positive implied the possibility for endocrine therapy. The content and distribution of ER and PR in normal cervical tissues are consistent with the effects of sex hormone.

Carcinoma, Squamous Cell↗
PubMed1992

[Effect of radix Astragali and radix ginseng in enhancing the metabolism of human myocardial cells in vitro].

Our experiment indicated that in Radix Astragali and Radix Ginseng treated human myocardial cell cultures the level of LDH and SDH elevated in varying degrees and in Radix Ginseng treated cells the cAMP showed higher levels but in Radix Ginseng treated ones the same was not observed. This suggests that the metabolism of myocardial cells is enhanced by Radix Astragali or Radix Ginseng.

Cells, Cultured↗
PubMed1992

A scanning electron microscopic observation of inner carious dentin after cleansing and of the dentin-resin interface.

Inner carious dentin after cleansing and the dentin-resin interface were observed with scanning electron microscopy. Results suggested that, similar to 10% citric acid-3% ferric chloride solution, 10% ethylenediaminetetraacetic acid may thoroughly remove the smear layer on the surface of inner carious dentin and make it possible for the dentinal bonding agent to penetrate the cleansed dentin to form an acid-proof layer and dense resin tags. These changes may improve the bond strength as well as tubule aperture seal. Ethylenediaminetetraacetic acid is not destructive to collagen, and may be of negligible toxicity to the pulp of intact dentin.

Acid Etching, Dental↗
PubMed1992

Indoor air pollution and pulmonary function in children.

Pulmonary function in winter time in 1,343 school children aged 10-13 years was measured in four cities located in northern and southern part of China. The results showed that FVC, FEV1, PEF, V75, V50 and V25 in children living in homes with coal stoves were decreased by 1.5-10.7% compared with children living in homes with gas or LPG stoves in Chengde and Shanghai. In contrast to this, no significant difference in pulmonary function was found in Shenyang and Wuhan. It suggested that this phenomenon was related to indoor air pollution, and partly related to passive smoking or outdoor air pollution.

Air Pollution, Indoor↗
PubMed1991

Regulated expression of three C/EBP isoforms during adipose conversion of 3T3-L1 cells.

In an effort to identify protein factors that play a regulatory role in the differentiation of adipocytes, we have isolated two genes that encode polypeptides related to CCAAT/enhancer-binding protein (C/EBP; hereafter termed C/EBP alpha). The proteins encoded by these C/EBP-related genes, termed C/EBP beta and C/EBP delta, exhibit similar DNA-binding specificities and affinities compared with C/EBP alpha. Furthermore, C/EBP beta and C/EBP delta readily form heterodimers with one another as well as with C/EBP alpha. The transcriptional activating capacity of these two newly identified C/EBP isoforms was demonstrated by transient transfection experiments in which expression vectors encoding C/EBP beta and C/EBP delta were observed to induce transcription from the promoter of the serum albumin gene in cultured hepatoma cells. The mRNAs encoding C/EBP beta and C/EBP delta were detected in a number of tissues, most of which corresponded to sites of expression of C/EBP alpha. The expression pattern of C/EBP beta and C/EBP delta during adipose conversion of 3T3-L1 cells was examined by Western and Northern blotting assays. In contrast to the expression profile of the gene encoding C/EBP alpha, whose product is not detectable until the late phase of adipocyte differentiation, the c/ebp beta and c/ebp delta genes were actively expressed very early during adipocyte differentiation. Moreover, transcription of the c/ebp beta and c/ebp delta genes was observed to be induced directly by adipogenic hormones. The accumulation of C/EBP beta and C/EBP delta reached a maximal level during the first 2 days of differentiation and declined sharply before the onset of C/EBP alpha accumulation. The temporal pattern of expression of these three C/EBP isoforms during adipocyte differentiation may reflect the underpinnings of a regulatory cascade that controls the process of terminal cell differentiation.

Adipose Tissue↗
PubMed1991

[Immunodiagnosis of ovarian cancer].

Ovarian tumor associated antigen was isolated from human serous cystadenocarcinomas of ovary and purified by using affinity chromatography columns coupled to anti-normal female serum and anti-normal ovarian tissue gamma globulin. Antiserum was prepared from New Zealand white rabbits. The antiserum was absorbed with normal female serum and extracts of normal ovarian tissue thoroughly. The absorbed antiserum was appraised by immunodiffusion, immunoelectrophoresis and counter-immunoelectrophoresis with intensifiers. The absorbed antiserum has a specific immune precipitin with extracts of ovarian tumor tissue. Counter-immunoelectrophoresis with intensifiers was used to detect the ovarian tumor associated antigen in the tissue and serum of various patients. Twenty-eight of 40 ovarian tumor extracts and 1 of 5 cervical carcinoma extracts showed the presence of the cancer antigen. 14/40 were positive in the sera of ovarian tumor patients and 6/10 positive in the sera of ovarian serous cystadenocarcinoma patients; 1/5 positive in the sera of cervical carcinoma patients and 2/10 positive in the sera of ovarian cysts patients. No positive result for the sera of normal females was noted. The specificity, sensitivity and accuracy of the method were 94.7%, 42.3% and 83.3%, respectively.

Adenocarcinoma↗
PubMed1991

[Preparation of monoclonal antibodies against chorionic gonadotropin receptor and study of its characteristics].

We reported the production of monoclonal antibodies (McAbs) against chorionic gonadotropin hormone (CG) receptor by fusing spleen cells of BALB/c mice which had been immunized by purified bacteria (Pseudomonas maltophilia) CG receptor with mouse myeloma line SP2/0. Four hybridoma cell lines secreting CG receptor McAbs were obtained (ED490 DG390, AB890 and GE590). The titers of specific antibodies of both mice ascites and culture supernatant were 10(-2)-10(-6) and 1-10(-2) respectively, by solid phase ELISA. Double-Immunodiffusion test showed that the McAb GE590 was IgG1, and the McAbs ED490, DG390 and AB890 were IgG2b Immunoprecipitation indicated that 125I-HCG could bind the HCG receptor which had reacted with McAbs ED490, AB890 and DG390, suggesting that they may recognize the receptor with different antigenic determinant. Interaction of McAb GE590 with the receptor showed that the increased concentration of GE590 was in inverse proportion to the amount of 125I-HCG binding receptor, indicating that both the McAb and 125I-HCG could recognize a common site of receptor and that increased concentration of McAb GE590 may induce some change in conformation and structure of the receptor. Our study suggested that these McAbs may be used for studying structure of CG receptor.

Animals↗
PubMed1991

Increased AMPA-sensitive quisqualate receptor binding and reduced NMDA receptor binding in epileptic human hippocampus.

Based on results from the kindling model of epilepsy, we hypothesized that enhanced binding of radioligands to the NMDA receptor and decreased binding to the alpha-amino-3-hydroxy-5-methyl-4- isoxazolepropionate (AMPA)-sensitive quisqualate (ASQ) receptor would be found within epileptic hippocampi of humans with complex partial epilepsy (CPE). To test these hypotheses, we used tissue that was surgically removed from patients with intractable CPE, and control tissue that was obtained at autopsy. We used autoradiographic techniques to measure ASQ receptor binding (with 3H-AMPA as the radioligand) and binding to 2 sites on the NMDA receptor/channel complex: the agonist recognition site (with 3H-glutamate) and the phencyclidine (PCP) binding site that resides within the NMDA channel [with 3H-N-(1-[thienyl]cyclohexyl) piperidine (TCP) in the presence of saturating concentrations of NMDA and glycine]. Measurements of receptor binding were corrected for pathologic alterations in neuronal density. Contrary to our expectations, ASQ receptor binding was significantly increased (100%; p less than 0.02) in the dentate gyrus stratum moleculare in patients with CPE (n = 8), and it was unchanged in other hippocampal regions. In nearby sections from the same specimens, binding was significantly decreased to the agonist recognition site of the NMDA receptor in the stratum oriens of area CA3 (46%; p less than 0.05) and was also decreased to the PCP site in the stratum radiatum and stratum oriens of CA3 (44% and 74%, respectively; p less than 0.05). The increase in ASQ receptor binding may contribute to hyperexcitability in these epileptic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Regulation of cell-type-specific transcription and differentiation of the pituitary.

The transcription of rat prolactin and growth hormone genes in vitro requires a pituitary transcription factor, specific to certain cell types in the pituitary, which currently appears to be the PUF-I/Pit-1/GHF-1 protein. This factor binds to cis-regulatory elements in the 5' region of both genes and exerts a positive influence on transcription initiation presumably by interacting with general transcription factors. The PUF-I/Pit-1/GHF-1 transcriptional regulatory protein probably has an important role in not only the differentiation of the pituitary lactotroph/somatotroph cell lineage; it is also expressed in the early development of the nervous system but its function there is less well documented. It appears to be one member of a family of trans-activator proteins involved in differential gene expression in several cell types.

Animals↗
PubMed1990

[3H]prostaglandin uptake in vivo by rabbit uterine tissues and blastocysts.

Day-6 pregnant rabbits were anesthetized and subjected to a mid-ventral laparotomy. [3H] Prostaglandin F2alpha) (PGF2alpha) [3H]PGE2, [14C]Urea or [14C]Sucrose were instilled into the uterine lumen via the uterotubal junction. The amounts instilled/uterine horn were respectively 3.7 +/- 0.3, 3.5 +/- 0.3, 5.7 +/- 1.3 and 2.7 +/- 1.6 muCi in 20mul of buffer. Animals were killed at 1, 2, 9, 19 or 21 h after radioactive instillation, and the amounts of radioactivity in blastocysts, uterine tissue, peritoneal cavity washings and urine evaluated by liquid scintillation spectrometry. A gradient of radioactivity was observed from the uterotubal junction to the cervical end of the uterus. Large amounts of [3H]PG were found in the injected horn and associated blastocysts with a considerable crossover to the non-injected horn, but little in the associated blastocysts. Much of the blastocysts associated- [3H]PG remained unmetabolized. Large amounts of metabolized [3 H] were found in urine. [14C]Urea was taken up by uterine tissue in the injected horn, but there was little cross over to the non-injected horn. Urea was also found in urine. Much of the [14C]Sucrose remained in the injected horn, and little was recovered from the urine. It was found that at 9 h, but not at 19 h, after [3 H]PG instillation, the PG was localized at the site of the blastocysts in the injected but not in the contralateral horn. Significantly more [3H]PGF2alpha than [3H]PGE2 was localized in this situation. [14C]Urea was not localized at the site of the blastocysts in urea injected horns. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Production and characterization of anti-human hepatocellular carcinoma monoclonal antibodies].

The hepatocellular carcinoma (HCC) cell line, QGY-7703, derived from a Chinese patient, was used to immunize the BALB/c mice. Fifteen hybridomas producing McAb that reacted with QGY-7703 cells were isolated from 858 hybridomas created in three cell fusions. In further studies two McAb, namely, AQGY1 and A-QGY2, were selected which specifically stained HCC cells grown in vitro. The reactivity of these McAb was not removed by the absorption by homogenates of the normal liver, but was by homogenates of HCC cells. A-QGY1 and A-QGY2 also reacted definitely with HCC cells in liver tissues of HCC patients, but neither with other cells in the tissues nor with nontransformed liver tissues of the same patients. Furthermore these two McAb stained the adult or fetal liver tissues, nor all of the other normal or tumor tissues that had been tested. Blocking and absorbing experiments revealed that A-QGY1 and AQGY2 antigens had no immunohomogenicity with antigens such as HBsAg, HBcAg, HBeAg, AFP and CEA. The specificity of these two McAb may be used potentially for the sero diagnosis, histologic identification, radioimmunoimaging and destruction of human hepatocellular carcinoma.

Antibodies, Monoclonal↗
PubMed1990

[Electron microscopic observation of the effects of Rhodiola kirilowii (Regel.) Maxim. in preventing damage of the rat viscera by a hypoxic high altitude environment].

This paper has shown that the pathologic damages done to rat's viscera due to hypoxic environment of altitude can be reduced significantly by oral administrations of Shengmaiyin, Danshen-Chuanxiong mixture and Rhodiola kirilowii. Shengmaiyin that maintains interior substances in the plate layer bodies proves more effective than Danshen-Chuanxiong mixture, while the latter excels in preventing capillary contraction, thus improving blood circulation. Rhodiola kirilowii has the effects of both Shengmaiyin and Danshen-Chuanxiong mixtures.

Altitude Sickness↗