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C Zhou

Publications and source records attributed to C Zhou.

At least 181 records · Page 10Linked to original sources
PubMed1997

The expression cassette determines the functional activity of ribozymes in mammalian cells by controlling their intracellular localization.

In order to better understand the influence of RNA transcript context on RNA localization and catalytic RNA efficacy in vivo, we have constructed and characterized several expression cassettes useful for transcribing short RNAs with well defined 5' and 3' appended flanking sequences. These cassettes contain promoter sequences from the human U1 snRNA, U6 snRNA, or tRNA Meti genes, fused to various processing/stabilizing sequences. The levels of expression and the sub-cellular localization of the resulting RNAs were determined and compared with those obtained from Pol II promoters normally linked to mRNA production, which include a cap and polyadenylation signal. The tRNA, Ul, and U6 transcripts were nuclear in localization and expressed at the highest levels, while the standard Pol II promoted transcripts were cytoplasmic and present at lower levels. The ability of these cassettes to confer ribozyme activity in vivo was tested with two assays. First, an SIV-growth hormone reporter gene was transiently transfected into human embryonic kidney cells expressing an anti-SIV ribozyme. Second, cultured T lymphocytes expressing an anti-HIV ribozyme were challenged with HIV. In both cases, we found that the ribozymes were effective only when expressed as capped, polyadenylated RNAs transcribed from Pol II cassettes that generate a cytoplasmically localized ribozyme that facilitates co-localization with its target. We also show that the inability of the other cassettes to support ribozyme-mediated inhibitory activity against their cytoplasmic target is very likely due to the resulting nuclear localization of these ribozymes. These studies demonstrate that the ribozyme expression cassette determines its intracellular localization and, hence, its corresponding functional activity.

Animals↗
PubMed1997

Gene regulation studies of aromatase expression in breast cancer and adipose stromal cells.

The expression of aromatase in human breast tumors was studied using the reverse transcription-polymerase chain reaction (RT-PCR) method on 70 breast tissue specimens. An RT-PCR analysis using two oligonucleotide primers derived from exon II of the human aromatase gene revealed that aromatase mRNA was detected in all but three tissue specimens. Furthermore, primer-directed RT-PCR was performed to determine the exon I usage in aromatase mRNA in these breast tumor specimens. The analysis revealed that exons I.3 and PII are the two major exons I present in aromatase mRNA isolated from breast tumors, suggesting that promoters I.3 and II are the major promoters driving aromatase expression in breast cancer and surrounding adipose stromal cells (ASCs). Recently, the regulatory properties of a 696-base pair region that contains promoter II, and is situated immediately upstream of exon II of the human aromatase gene, were investigated. Detailed DNase 1 footprinting analysis, DNA mobility shift assays, and chloramphenicol acetyltransferase (CAT) functional studies of this genomic region were performed and led to the identification of a segment (B1) that could act as a promoter (probably promoter I.3) in adipose stromal and breast cancer cells. The study further revealed that the B1 region could be divided into two domains which were designated RE1 and RE2. RE1 was found to have the promoter activity, and RE2 was found to regulate the promoter activity of RE1, but in different manners in MCF-7 cells (as an example of breast cancer cells) and in ASCs. RE2 was found to function as a positive regulatory element in MCF-7 cells and as a negative regulatory element in ASCs, respectively. It was also found that in several breast cancer cell lines, including MCF-7, the promoter activities of both promoter II and promoter I.3 were found to be suppressed by a negative regulatory element, a silencer, present in the 162 bp fragment which is located upstream from promoter II and downstream from promoter I.3. The precise position of the silencer element (termed S1) was localized by deletion mutation and DNase 1 footprinting analysis, and the silencing activity of S1 on promoter I.3 (in B1 fragment) was confirmed by CAT plasmid transfection experiments. UV crosslinking experiments are being performed to examine the regulatory proteins interacting with the silencer element. These studies serve as the basis for the further characterization of the regulatory mechanism of aromatase expression in human breast cancer and ASCs.

Adipose Tissue↗
PubMed1997

A new method for computerized tomography diagnosis of early transtentorial hernia.

OBJECTIVE: To evaluate a new scanning method designed for the diagnosis of early transtentorial hernia as compared with the routine scanning method (parallel to orbitomeatal line). METHODS: 102 patients with unilateral high intracranial pressure and 100 volunteers without any cranial symptoms and signs were scanned on (1) the plane perpendicular to the plane of clivus and (2) the plane parallel to orbitomeatal line, a line joining the apex of the dorsum sellae and the lowest point of the clivus. RESULTS: Vertical-to-clivus scanning method directly demonstrated the temporal transtentorial hernia in 48 of 102 patients with unilateral high intracranial pressure, but the orbitomeatal line scanning method was not able to show this direct finding. The projected tissue of the temporal lobe could be obviously shown and the degree of the hernia could be judged directly on the CT imaging with the vertical-to-clivus scanning method. Therefore, the CT diagnosis criterion of the hernia was suggested as follows: the hernia would be determined if the downward shift of the temporal lobe was more than 3 mm and suspected if less than 3 mm with ipsilateral high intracranial pressure. CONCLUSION: This new method presented a superiority in showing the temporal transtentorial hernia for the patients with a cranial emergency.

Adult↗
PubMed1997

Changes of ultrasonography and two serum biochemical indices for hepatic fibrosis in schistosomiasis japonica patients one year after praziquantel treatment.

OBJECTIVE: To observe the changes of abdominal sonography and 2 biochemical indicators for hepatic fibrosis before and after treatment with praziquantel in schistosomiasis japonica patients. METHODS: Fifty-five persons infected with Schistosoma japonicum and treated with praziquantel were examined with ultrasonography and serum hyaluronic acid (HA) and type III procollagen (PC III) before and 1 year after treatment, and their data were compared with those in 55 normal controls. RESULTS: With comparison of the data before praziquantel treatment, the length of the left liver lobe and the spleen in 55 patients all decreased (P < 0.01) 1 year after treatment. No significant change was seen in interior diameter (d) of the portal vein, while a decrease in the ratio of the exterior diameter (D) and interior diameter of the second branch of the portal vein was very significant (P < 0.01). Compared with the data in normal control, significantly higher levels in the thickness of the left lobe, the maximum oblique diameter of the right lobe, the length of the spleen, spleen index, the interior diameter of the portal vein and D/d ratio were seen in the patients both before and after treatment. The abnormal rate of the 2 serum parameters for hepatic fibrosis decreased significantly after treatment. CONCLUSIONS: Parameters of hepatic fibrosis either by ultrasonography or by the 2 biochemical tests showed a significant improvement in 55 patients 1 year after treatment, although some of the indices did not yet return to normal levels.

Adolescent↗
PubMed1997

[A four-box multi-function testing system of pharmacology reaction].

The organism position matrix method, a new method of testing pharmacology reaction is proposed. On the basis of the method, we have developed a four-box multi-function testing system which can test the spontaneous activity, analgesic effect, and learning and memory ability of 1 to 4 mice in three dimensions respectively. Four quantitative parameters, the total distance, the movement intensity, the vertical number and the jumping number are put forward to describe the spontaneous activity. The starting time of continuous jumping and the jumping number are used to describe the analgesic effect. The time from the electrical shock to escape onto a safety platform and the number of the electrical shock are used to describe the learning and memory ability. The system has the characteristics of good repeatability, high efficiency, quantitative and automatic control.

Animals↗
PubMed1996

Mechanism and structure based inhibitors of phospholipase C enzymes.

PI-specific PLC enzymes are a key component of phosphatidylinositol-mediated signaling pathways since the hydrophobic product, diacylglycerol, activates protein kinase C and the water-soluble product, inositol trisphosphate, is involved in Ca2+ mobilization. Nonspecific, or PC-PLC, enzymes can generate diacylglycerol without Ca2+ mobilization. A series of inhibitors, both lipophilic and water-soluble, have been synthesized to target each of these two classes of PLC enzymes. Design of the inhibitors was based on proposed enzyme mechanisms and available crystal structures. The solution conformations of the lipophilic phospholipid analogs, (diheptanoylphosphatidyl(2-O-methyl)inositol for PI-PLC and a dihexanoyl-sn-(3-N-benzylaminoglycero)phosphoramidocholine for PC-PLC, have been determined using NMR methodology and the interaction of these compounds with bacterial enzymes has been examined. Water-soluble inhibitors include strained cyclic phosphonates for PI-PLC and vanadate for PC-PLC. An eventual goal of this work is to generate compounds that specifically target each type of intracellular PLC activity.

Bacillus cereus↗
PubMed1996

Apoptosis of mouse MS-2 fibrosarcoma cells induced by photodynamic therapy with Zn (II)-phthalocyanine.

The destructive process of mouse MS-2 fibrosarcoma induced by photodynamic therapy (PDT) with liposome-administered Zn(II)-phthalocyanine (ZnPc) was studied by electron microscopy. Pronounced ultrastructural changes characteristic of apoptosis were observed for several tumour cells, including early occurrence of condensation and margination of chromatin, disappearance of nuclear pores, karyopyknosis, karyorrhexis, protuberance formation at the cell surface and cell fragmentation. The findings indicate that apoptosis was involved in the process of tumour cell death induced by ZnPc-PDT. The detailed mechanism and pathways controlling this phenomenon need to be elucidated further.

Animals↗
PubMed1996

Aromatase gene expression and its exon I usage in human breast tumors. Detection of aromatase messenger RNA by reverse transcription-polymerase chain reaction.

The expression of aromatase in human breast tumors has been studied by the reverse-transcription polymerase chain reaction (RT-PCR) method on 70 breast tissue specimens. An RT-PCR analysis using two oligonucleotide primers derived from the exon II of the human aromatase gene revealed that aromatase mRNA was detected in all but three tissue specimens. Furthermore, primer-directed RT-PCR was performed to determine the exon I usage in aromatase mRNA in these breast tumor specimens. The analysis has revealed that exons I.3 and PII are the two major exon Is present in aromatase mRNA isolated from breast tumors, suggesting that promoters I.3 and II are the major promoters driving aromatase expression in breast cancer and surrounding adipose stromal cells. The RT-PCR analysis also detected two products, I.3A (334 bp in length) and I.3B (222 bp in length), when it was carried out using a primer derived from exon I.3 and a reverse primer derived from exon II. The nucleotide sequences of these products have been determined and indicate that I.3A contains a region which was previously thought to be an intron. In addition, RT-PCR analyses of RNA isolated from eight pairs of breast tumor and neighboring normal tissue specimens were performed to evaluate the exon I usage and the distribution of I.3A- and I.3B-containing aromatase RNA messages in breast tumor and neighboring normal tissues. The results suggest that I.3B- and I.3A-containing messages are mainly present in breast tumor and neighboring normal tissues, respectively. Finally, the exon I/promoter usage for aromatase expression in eight cell lines (skin fibroblast, MCF-7, MDA-MB-231, T-47D, SK-BR-3, JAR, OVCAR-3, and human adipose stromal cells) was examined by primer-directed RT-PCR analyses. These studies provide a basis for further evaluation of the control mechanism of aromatase expression and estrogen biosynthesis in breast tumors.

Adipose Tissue↗
PubMed1996

Expression of hammerhead ribozymes by retroviral vectors to inhibit HIV-1 replication: comparison of RNA levels and viral inhibition.

We have analyzed expression of anti-HIV-1 hammerhead ribozymes in the context of retroviral vectors. To determine optimal vector designs for ribozyme expression, we compared three vectors, each of which contained the same pair of anti-HIV-1 hammerhead ribozymes in tandem. Despite the presence of vastly different amounts of vector-derived flanking sequences, the ribozymes produced by each vector had similar cleavage activity when assayed in vitro. The ribozyme vectors were packaged into amphotropic virion and used to transduce human CEM T lymphocytes. Analysis by Northern blot and RNAse protection assays demonstrated that the highest steady-state levels of ribozyme-containing transcripts were produced by a vector in which the ribozymes were expressed under transcriptional control of the vector MoMuLV LTR. Despite these differences in the levels of ribozyme transcripts achieved by the vectors, their ability to confer resistance to HIV-1 replication was similar. Therefore, other factors than the absolute levels of ribozymes play a role in determining the effectiveness of ribozyme vectors to inhibit HIV-1. These may include structural features of the transcripts that affect the antisense effects of the ribozyme constructs, the actual catalytic activity of the ribozymes, their RNA folding, the binding of proteins, and the intracellular localization. Greater understanding of these factors may permit more effective application of ribozymes to inhibit gene expression.

Base Sequence↗
PubMed1996

[Fertilization in vitro and embryo transfer by combined long-acting gonadotropin releasing hormone agonist and gonadotropin for superovulation in patients with refractory polycystic ovary syndrome].

OBJECTIVE: To investigate the efficacy of the treatment for polycystic ovary syndrome (PCOS) patients by combined long acting gonadotropin-releasing hormone agonist (GnRHa) and gonadotropin. METHODS: Nineteen women with PCOS who had failed to conceive on treatment with conventional fertilization in vitro-embryo transfer (IVF-ET) protocol underwent 26 cycles of IVF-ET by combined long-acting and gonadotropin stimulation. A self-control group consisted of 19 PCOS women who had received 19 treatment cycles with conventional IVF-ET stimulation protocol more than 6 months previously. RESULTS: A comparison of these two groups showed that treatment with combined long-acting GnRHa and gonadotropin improved the in vitro fertility rate (76.2%) and pregnancy rate (38.5%). CONCLUSION: Patients with refractory PCOS should be referred for IVF-ET, using long-acting GnRHa before gonadotropin as the stimulation protocol.

Adult↗
PubMed1996

[Image morphological quantitative analysis of pathological changes of intra-acinar arteries in experimental pulmonary artery hypertension and outcomes of treatment].

The relative ratios of vessel lumen area/total area (EA/TA), vessel wall area/total area (MA/TA) and vessel wall thickness/vessel external diameter (WD/TD) of intra-acinar arteries were studied with image analysor in 35 rats of experimental pulmonary artery hypertension and outcomes of treatment. All the rats were divided into control group (R0), hypertension group (R1) and treated groups (R2), (R3) and (R4). The results showed relative ratios of EA/TA decreased significantly in the palmonary artery hypertension group in comparison with the control and treated groups, while the values of WA/TA and WD/TD increased significantly. The results may be valuable for morphological quantitative study, diagnosis of pulmonary artery hypertension and prediction of the disease prognosis.

Alkaloids↗
PubMed1996

[Loss of CDKN2 gene and amplification of cyclin D1 gene in human esophageal cancer].

The products of both CDKN2 and cyclin D1 genes are negative and positive regulators respectively in cell cycle. To study the involvement of the CDKN2 tumor suppressor gene and cyclin D1 oncogene in esophageal cancer development, we examined the situation of both genes in 21 pairs of primary human esophageal cancers and the mucosa adjacent to the cancers and also in four esophageal cancer cell lines by means of molecular biological and immunohistochemical techniques. Homozygous deletion was observed in 6 out of the 21 primary cancers and with lymph node metastasis in 5 out of the 6 cases. Loss of expression of p16 protein was identified immunohistochemically in 8 out of 21 primary cancers. Amplification of cyclin D1 was found in 12 out of 21 primary cancers and in 5 esophageal mucosa adjacent to the tumors, accompanying with overexpression of cyclin D1 protein. Homozygous deletion was observed in one (EC8712) out of the four cell lines, while by Northern and immunohisto chemistry analysis, loss of transcription of CDKN2 mRNA and loss of p16 protein expression were observed in two cell lines (EC8712 and EC8501). Amplification and overexpression of cyclin D1 were found in two cell lines (EC8733 and EC8501). These findings suggest that loss of CDKN2 gene and amplification of cyclin D1 gene are involved in esophageal cancers and that cyclin D1 alteration may be a earlier molecular event while CDKN2 to be a later one.

Carcinoma, Squamous Cell↗
PubMed1996

[Evaluation of radiotherapy for state I ovarian carcinoma].

To investigate the role of radiotherapy for stage I epithelial ovarian carcinoma, the results in 91 patients treated from 1970-1989 were retrospectively analysed. There were 60 patients treated by operation combined with chemotherapy, 31 patients by operation combined with chemotherapy and radiotherapy. Patients in both groups were comparable with regard to age, clinical stage, histology grade, type of operation and chemotherapeutic regimen. The 5-year actuarial survival rate was 78.3% for those receiving additional radiotherapy and 72.4% for those without additional radiotherapy. The recurrence rate was 32.2% with a median recurrence time of 34 months in the former group while 60.6% and 18.6% months for the latter. Radiotherapy did not confer survival advantage in the treatment of stage I ovarian cancer, but it could decrease recurrence rate and delay onset of recurrence.

Adenocarcinoma, Mucinous↗
PubMed1996

[The expression of Rb, p16 and cyclin D1 in 41 esophageal cancers].

D-type cyclins being considered as oncogenes promote progression of the cell through the G1 phase of the cell cycle by CDK4 mediated phosphorylation of the retinoblastoma protein. The activities of CDK4 is constrained by inhibitors such as p16, the product of the CDKN2 in tumor cells and primary tumors suggests that p16 acts as a tumor suppressor. We examined these proteins and genes by immunohistochemistry and in situ hybridization techniques in 41 primary esophageal cancers. Overexpression of cyclin D1 was revealed in 26/41 samples (63.4%) and also in the mucosa adjacent to the cancers in 10 of 26 cyclin D1 overexpression samples, which also have high levels of cyclin D1. P16 was undetectable in 13 of 41 samples. Interestingly, 17 of 24 Rb positive cancers had no or low p16, while 9 Rb-negative cancers showed high levels of p16. These results suggest that the overexpression of cyclin D1 may be a common molecular abnormality and an early molecular event in esophageal cancer, followed either by Rb loss, as occurred in Rb negative samples, or by loss of p16, as occurred in p16 negative samples. Cyclin D1 overexpression and Rb inactivation can coexist in esophageal cancer. However, there is a reciprocity between Rb inactivation and p16 expression in esophageal cancer. Thus, abnormality in the negative feedback regulatory pathway of cyclin D1/CDK4, Rb and p16 may be involved in the molecular mechanism of esophageal cancer.

Carcinoma, Squamous Cell↗
PubMed1996

[Observation of relationship between function and structure of experimental pulmonary artery hypertension in rats and inhibitory effect of garlicin and other herbal medicines].

The paper deals with the treatment of the pulmonary artery hypertention in rats caused by monocrotaline with garlicin, liqustrazine and berbamine and studies the relationship between the function and structure of pulmonary artery and pulmonary artery hypertension before and after use of hypotensive agents. The results show that there is a close relationship between the function and structure of pulmonary artery and pulmonary hypertension, and the inhibitory effect of garlicin is the strongest among the three herbal medicines. The pathogenesis is also studied.

Alkaloids↗
PubMed1995

Retroviral-mediated gene expression in human myelomonocytic cells: a comparison of hematopoietic cell promoters to viral promoters.

Gene transfer into human hematopoietic stem cells with expression targeted to the maturing myelomonocytic progeny has applications for gene therapy of genetic diseases affecting granulocytes and macrophages. We hypothesized that promoters of myeloid-specific genes that are upregulated with myelomonocytic differentiation would also upregulate expression of an exogenous gene in a retroviral vector. Moloney murine leukemia virus (MoMuLV)-based retroviral vectors using promoters from hematopoietic genes (CD11b, CD18, and CD34) were compared with vectors with viral promoters (MoMuLV long terminal repeat [LTR], cytomegalovirus [CMV], and simian virus 40 [SV40]). Human glucocerebrosidase (GC) cDNA was the reporter gene. HL60 cells were transduced with these vectors and vector-derived GC activity was compared in undifferentiated HL-60 cells and the same cells differentiated into granulocytes using dimethyl sulfoxide or monocyte/macrophages using phorbol myristate acetate. In undifferentiated HL-60 cells, vector-derived GC activity was the highest when it was controlled by the MoMuLV LTR. In HL-60 cells differentiated into granulocytes, vector-derived GC activity transcribed from the CD11b, MoMuLV LTR, and CMV promoters was equivalent to 1.7, 1.5, and 1.5 times the normal endogenous GC activity, respectively, and 0.8, 2.0, and 3.6 times the normal GC activity, respectively, in those differentiated into macrophages. With granulocytic differentiation, the CD11b promoter showed maximal induction in GC activity (8-fold); with macrophage differentiation, the CD11b promoter showed a fourfold induction in GC expression. The CD11b promoter also generated significant levels of GC activity in the myelomonocytic progeny of transduced CD34+ cells. Expression from the CD11b promoter, unlike that from the CMV or the MoMuLV LTR promoters, was relatively myelomonocyte-specific, with minimal expression observed in Jurkat T cells or HeLa carcinoma cells. The induction of expression from the CD11b promoter with differentiation in HL-60 cells correlates with the developmental regulation of the CD11b gene. Retroviral vectors using the CD11b promoter have potential utility for gene therapy of disorders affecting the myelomonocytic lineage.

Antigens, CD34↗
PubMed1995

Morphological features of collateral innervation and supernumerary innervation in the skeletal muscles of presenile rats.

Using silver impregnation either with or without cholinesterase staining, this study was designed to investigate the morphological patterns of remodeling in both the arborization of axon terminals and in the subneural apparatus of the motor endplate in adult rats (3, 6, and 12 months old). The coincidental growth of the nerve terminal and muscle fiber was observed to continue, and the number of muscle fibers remained unchanged up to 12 months of age. In 12-month-old muscles, as compared with those of the younger subjects, the frequencies of 1) terminals with signs of degeneration, growth, or both, 2) denuded postsynaptic cholinesterase sites not associated with the overlying axon, 3) collateral innervation, and 4) supernumerary innervation, were all seen to have increased. The functional terminal innervation ratio was increased to 1.06. The characteristic features consisted of enhanced collateral formation by means of ultraterminal sprouting, and of multiple axons proceeding to an already innervated endplate. An imbalance between growth and degeneration in the motor endplates during the presenile stages is thus a likely stimulus for the particular compensatory changes to increase the size of the motor unit.

Aging↗