Biomedical subjects

J Zou

Publications and source records attributed to J Zou.

At least 91 records · Page 5Linked to original sources

PubMed1999

Protein Kinase C Mediates Prolactin Regulation of Mitochondrial Aspartate Aminotransferase Gene Expression in Prostate Cells.

Prolactin stimulates citrate accumulation in prostate cells by increasing the expression of mitochondrial aspartate aminotransferase (mAAT). In this study, we further investigated the mechanism of prolactin regulation of mAAT expression in rat lateral prostate and LNCaP and PC-3 prostate cancer cells. Prolactin and 12-O-tetra-decanoylphorbol 13-acetate (TPA) increased the mAAT mRNA level twofold to fourfold. In addition, prolactin and TPA increased protein kinase C (PKC) activity in prostate cells 20% to 60% and 40% to 210%, respectively. The effects of both prolactin and TPA on mAAT mRNA were eliminated by downregulation of PKC. The effect of prolactin and TPA on gene transcription was determined using mAAT-chloramphenicol acetyltransferase (CAT) reporter-gene constructs, transiently transfected into PC-3 cells. The 59 untranslated region of the precursor form (pmAAT) of the mAAT gene contains five sequences that are homologous to the consensus TPA response elements (TRE). Reporter constructs with various combinations of these sequences were used to assay prolactin stimulation of CAT transcription in PC-3 cells. Prolactin increased CAT expression in PC-3 cells transfected with a reporter gene containing four of the TRE consensus sequences. Another CAT reporter gene, which contained two of the putative TREs, was also stimulated by prolactin, but a third reporter, containing the two other TRE sequences, was not induced by prolactin. These results suggest that prolactin regulates mAAT at the transcriptional level. Moreover, because both prolactin and TPA induced PKC activity, and because the effects of prolactin and TPA were eliminated when PKC was downregulated, we postulate that the prolactin effect on mAAT expression is mediated via the diacylglycerol PKC signal transduction pathway in rat lateral prostate and human prostate cancer cells.

Journal Article↗

PubMed1999

[Affect of insulin-like growth factor I and estradiol on the growth of uterine leiomyoma].

To study roles of insulun-like growth factor 1(IGF-I) and estradiol(E2) in the growth of leiomyoma. Protein expressions of IGF-I receptor(IGF-I-R), estrogen receptor(ER), and cell proliferation associated nuclear antigen(ki-67) were analysed by streptavidin-peroxide method in 40 cases. Serum level and local concentration of IGF-I were determined by immunoradiometric assay(IRMA) in 20 cases. Serum level of estradiol was determined by radioimmunoassay in 20 cases. Twenty normal fertile women were studied as control. Protein expressions of IGF-I-R and ER in uterine leiomyoma were significantly higher than in myometrium(P < 0.05); and local concentration of IGF-I positively correlated with ki-67 (r = 0.6513, P < 0.05); and expression of estrogen receptor. The serum levels of IGF-I and E2 had no significant difference between leiomyoma patients and normal women. IGF-I and E2 promote the growth of leiomyoma and IGF-I may act as a mediator of estrogen.

Adult↗

PubMed1998

Repression of heat shock transcription factor HSF1 activation by HSP90 (HSP90 complex) that forms a stress-sensitive complex with HSF1.

Heat shock and other proteotoxic stresses cause accumulation of nonnative proteins that trigger activation of heat shock protein (Hsp) genes. A chaperone/Hsp functioning as repressor of heat shock transcription factor (HSF) could make activation of hsp genes dependent on protein unfolding. In a novel in vitro system, in which human HSF1 can be activated by nonnative protein, heat, and geldanamycin, addition of Hsp90 inhibits activation. Reduction of the level of Hsp90 but not of Hsp/c70, Hop, Hip, p23, CyP40, or Hsp40 dramatically activates HSF1. In vivo, geldanamycin activates HSF1 under conditions in which it is an Hsp90-specific reagent. Hsp90-containing HSF1 complex is present in the unstressed cell and dissociates during stress. We conclude that Hsp90, by itself and/or associated with multichaperone complexes, is a major repressor of HSF1.

Benzoquinones↗

PubMed1998

Relationship between cellular uptake rate and chemical behavior of diammine/diaminocyclohexane platinum (II) complexes with oxygen-ligating anionic groups.

The uptake kinetics of the platinum (II) complexes of the formula Pt(NH3)2X, Pt(dach)X by human erythrocyte in the plasma isotonic buffer was studied. The results showed that across-membrane transport of all the platinum complexes studied follows a first-order kinetic process. The uptake rate constants decrease with the change of oxygen-ligating anionic group in the sequence: sulfato > selenato > anion of squaric acid > oxalato > anion of demethylcantharic acid > malonato and increase with increasing lipophilicity of carrier group. The relationship between uptake rate and reactivity of these complexes was established. The stereochemistry of dach isomers was shown without effect on the reactivity and the sequence.

Actins↗

PubMed1998

Detection of persistent vegetative bacteria and amplified viral nucleic acid from in-use testing of gastrointestinal endoscopes.

Hospital-acquired infection attributed to inadequate decontamination of gastrointestinal endoscopes prompted an in use evaluation of recommended procedures. Specimens were obtained from the internal channels of 123 endoscopes before, during and after decontamination by flushing with saline and brushing with a sterile brush, and examined for vegetative bacteria by broth and plate culture. Four endoscopy units were tested; the chemical disinfectants used were: 2% glutaraldehyde in Centres 1 and 2 (automated) and Centre 3 (manual); peracetic acid in Centre 4 (automated). Samples from patients in Centre 1 with known chronic hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV-1) infection were also examined for viral nucleic acid by ultracentrifugation, nucleic acid extraction, reverse transcription (for RNA) and polymerase chain reaction (PCR). No persistent vegetative bacteria were found following standard manual cleaning and disinfection for 20 min in 2% glutaraldehyde in Centres 2 and 3 (N = 37). At Centre 1, while plate culture yielded no growth, 34% of samples (10/29) grew vegetative bacteria in broth culture after cleaning and disinfection for 20 min in 2% glutaraldehyde. Investigation revealed an error in manual cleaning; no bacteria were detected in 37 samples taken after this was corrected. At Centre 4, despite the use of peracetic acid as a sterilant, three out of 20 (15%) of post decontamination samples grew bacteria; one contained persistent bacteria. HBV and HCV PCR analysis detected viral nucleic acid in three out of four and four out of six samples from viraemic patients undergoing endoscopy in Centre 1 during the period of improper manual washing. After proper cleaning was instituted, samples from nine out of nine HCV viraemic patients were negative. HIV RNA was detected in five of 14 samples taken from endoscopes after use on HIV positive patients but all post decontamination samples were negative. Detection of bacteria in washes from endoscope channels is a useful warning of a breakdown in decontamination practice. Inadequate brushing of internal channels may result in persistent HCV and HBV viral nucleic acid, the significance of which is not clear. These results reinforce the importance of adequate manual cleaning of endoscopes before chemical disinfection.

Bacteria↗

PubMed1998

Rainbow trout cytokine and cytokine receptor genes.

Transforming growth factor-beta (TGF-beta) and interleukin-1 beta (IL-1 beta) have been cloned from rainbow trout (Oncorhynchus mykiss) in our laboratory. The trout TGF-beta is typical of members of the cysteine knot cytokine family, and has highest homology to TGF-beta 1, TGF-beta 4 and TGF-beta 5. The gene organisation is different to other TGF-beta genes despite the presence of seven exons. Trout IL-1 beta has less homology to known IL-1 beta s (49-56% amino acid similarity) but shows clear conservation of the secondary structure of the "mature peptide". An interleukin-converting enzyme cut site is not apparent however, and it remains to be determined whether fish IL-1 beta must be cleaved for biological activity. The trout IL-1 beta gene consists of six exons, one less than in mammals, with the missing exon at the 5' end of the gene. Two trout chemokine receptors have also been isolated in our laboratory, having high homology to CXC-R4 and CC-R7 (67% and 56% nucleotide identity respectively). With a view to studying the biological effects of fish cytokines we have also cloned the inducible nitric oxide (iNOS) and cyclooxygenase (COX-2) genes in trout. Both have high homology to known mammalian and chicken genes, and have been shown to be inducible in trout.

Amino Acid Sequence↗

PubMed1998

Correlation between glutathione oxidation and trimerization of heat shock factor 1, an early step in stress induction of the Hsp response.

The heat shock protein (Hsp) response is induced by heat shock and a large variety of different chemicals. Searching for a common denominator of these different inducers, we and others developed the notion that all inducers may generate abnormally folded, i.e. non-native, proteins, and that such non-native proteins may trigger the Hsp response. Experimentation prompted by this notion resulted, for example, in the demonstration that chemically denatured proteins, introduced in cells by microinjection, can activate the response. Based on the chemical nature of inducers and on results reported from several studies, we hypothesized that inducers of the Hsp response may be generally capable of triggering oxidation of non-protein thiols, particularly glutathione. Such oxidation is known to lead to formation of glutathione-protein mixed disulfides and protein-protein disulfides. Presumably, thiol adduction and cross-linking would affect the structure of proteins involved, resulting in unfolding of a fraction of these proteins, causing heat shock factor (Hsf) activation. To test the feasibility of this hypothesis, thirteen different inducers were selected, and it was shown that all chemical inducers as well as heat shock cause drastic oxidation of glutathione under conditions under which they induce HSE DNA-binding activity. Under the same conditions, all chemical inducers and heat shock also cause trimerization of Hsf1. For several inducers, it was also shown that they enhance thiol oxidation of proteins. Finally, in vitro experiments support the notion that activation of Hsf1 does not require oxidation of the factor itself or of its coregulators. These results are in complete agreement with the above hypothesis.

Arsenites↗

PubMed1998

[Heat shock response in experimental acute middle ear bacterial infection].

OBJECTIVE: To investigate the association between bacteria antigen and inner ear antigen and effects of stress on the expression spectrum and level of the antigen bearing hsp70 related epitope. METHODS: Use monoclonal antibody against mammiferous hsp70 to recognize the related antigens of Bacillus pyocyaneus, Bacillus proteus, Bacillus coli, Staphylococcus aureus and Klebsiella pneumoniae with modified western blotting. The expression level of hsp70 in unstressed guinea pig inner ear was tested. An animal model of middle ear acute infection by Klebsiella pneumoniae was established. The dynamic changes of mammiferous hsp70 epitope related proteins were tested with modified western blotting. RESULTS: All the bacteria antigens recognized by anti-mammiferous hsp70 antibody were not of the hsp70 family and the expression level of hsp70 in normal guinea pig was extraordinarily low. Klebsiella pneumoniae expressed 70,000 dalton and 17,000 dalton hsp after its invasion into guinea pig middle ear. 70,000 dalton antigen expressed most intensely at 3rd day of invasion and then fell. 17,000 dalton antigen was expressed most intensely at 5th day of invasion and then fell. The expression of 70,000 dalton hsp was much weaker than 31,000 dalton hsp at acute periods of middle ear infection. CONCLUSIONS: The elevated expression of hsp both in bacteria and inner ear during middle ear acute infection provides material base for immune impairment on inner ear induced by bacterial infection. The low molecular weight hsp may be involved in the inner ear autoimmune impairment.

Animals↗

PubMed1997

Cloning and molecular characterization of an Arabidopsis thaliana RING zinc finger gene expressed preferentially during seed development.

The RING (Really Interesting New Gene) finger is a zinc-binding domain that is found in proteins from a variety of species. This paper reports the cloning and characterization of, as yet, only the second RING finger protein gene from plants, A-RZE, in Arabidopsis thaliana. In addition to the RING-finger motif, A-RZF also contains a putative nuclear localization signal. A-RZF is encoded by a single copy gene with an intron of 595 bp interrupting the 5' leader sequence and the coding region. Northern blot analysis indicated that A-RZF is expressed preferentially during seed development. The RING-finger motif, putative nuclear localization signal, and unique expression pattern, predict an important role during seed development for A-RZF.

Amino Acid Sequence↗

PubMed1997

Prolactin regulation of mitochondrial aspartate aminotransferase and protein kinase C in human prostate cancer cells.

Citrate production is a major physiological function of the prostate that is regulated by testosterone and prolactin. Mitochondrial aspartate aminotransferase (mAAT) is a key enzyme in the metabolic pathway of prostate citrate production. In addition, prolactin stimulates expression of mAAT in the rat lateral prostate. In this report we establish the role of prolactin in the regulation of mAAT in two prostate cancer cell lines, LNCaP and PC-3. LNCaP cells respond to hormonal stimulation with increased secretion of prostate specific products. PC-3 cells, on the other hand, are testosterone independent and apparently do not respond to other growth factors either. Results showed that both LNCaP and PC-3 cells responded to prolactin with increased mAAT activity and an increased steady state level of mAAT mRNA. Prolactin also increased protein kinase C (PKC) activity in both these cell lines. Treatment of LNCaP and PC-3 cells with the phorbol ester 12-O-tetradecanoylphorbol (TPA) caused the same effect on mAAT activity and mRNA level as prolactin. The results suggest that the diacylglycerol-PKC signal transduction system mediates the prolactin effect on mAAT. In addition, these results also show that the prolactin effect on mAAT is independent of androgens since PC-3 cells reportedly lack androgen receptor expression. Thus, these results provide evidence that prolactin is a physiological regulator of prostate function in human as well as rat prostate. In addition, the results also show that though prostate cancer cells are androgen independent, they remain responsive to prolactin. This could have important implications for the treatment and management of prostate cancer.

Animals↗

PubMed1997

Differential associations between the cytoplasmic regions of the interleukin-12 receptor subunits beta1 and beta2 and JAK kinases.

The role of the cytoplasmic regions of interleukin-12 receptors (IL-12R) beta1 and beta2 in stimulating proliferation was examined. The transmembrane and cytoplasmic regions of IL-12Rbeta1 or IL-12Rbeta2 were fused to the extracellular domain of the epidermal growth factor (EGF) receptor, yielding chimeric receptors E12R1 and E12R2, respectively. These chimeras were stably transfected into BaF3 cells, a factor-dependent murine pro-B cell line. Only E12R2 or E12R1+E12R2 transfectants were capable of EGF-dependent proliferation. EGF-dependent phosphorylation of E12R2, JAK2, Tyk2, and STAT3 was observed. JAK2 was phosphorylated in E12R1-, E12R2-, and E12R1+E12R2-expressing cells. However, direct associations were detectable only between E12R2 and JAK2. Tyk2 phosphorylation was observed only in cells expressing E12R1 or E12R1+E12R2. In parallel with this activation pattern, direct interactions only between Tyk2 and E12R1 were demonstrable. Phosphorylation of STAT3 was observed in cells expressing E12R1, E12R2, and E12R1+E12R2. The expression levels of STAT4 protein in BaF3 cells are undetectable by the methods employed here; therefore, STAT4 phosphorylation was not observed. Taken together, the data indicate that differential interactions take place between the cytoplasmic regions of the two IL-12R subunits and JAK2/Tyk2 and that the cytoplasmic region of IL-12Rbeta2 alone is capable of delivering a proliferative signal.

Barium Compounds↗

PubMed1997

Synthesis, antitumor activity and acute toxicity of diammine/diamino-cyclohexane platinum(II) complexes with oxygen-ligating leaving group.

In order to clarify the relation between the reactivity of the leaving groups in cisplatin-like complexes and their activity / toxicity, six new complexes of the formula Pt(NH3)2X and Pt(dach)X (where X is selenato, anion of squaric acid, or demethylcantharic acid) have been synthesized and compared. These complexes have been characterized by elemental analysis, infrared spectroscopy, and conductivity measurements. Six human neoplastic cell lines (HCT, KB, BGC, HL-60, K-563 and Bel-7402) were used to screen these compounds. The results demonstrated that four of them have comparable IC50 and even lower IC50 in a few kinds of tumor cell lines compared to cisplatin. Their LD50 values showed that the toxicity of these platinum complexes is related to the reactivity of the leaving groups. All of these complexes have lower acute toxicity than cisplatin, but the anticancer activity is not affected.

Actins↗

PubMed1997

The chirality selectivity in the uptake of platinum (II) complexes with 1,2-cyclohexanediamine isomers as carrier ligand by human erythrocytes.

The uptake kinetics of cisplatin analogs of 1,2-cyclohexanediamine(dach) isomers with various leaving groups, by human erythrocytes in plasma isotonic buffer, were studied. The experimental results showed that the uptake rate constants (k values) decrease with the change of leaving group in the sequence: chloride (Cl) > squaric acid (SA) > oxalate (OX) > demethylcantharic acid (DA), with the same dach isomer as carrier group. It is noteworthy that for the platinum (II) complexes with the same leaving group, the k values always reduce as: 1R, 2R-dach > 1R, 2S-dach > 1S, 2S-dach. This result reflects the chirality selectivity. No differences in reactivity to protein thiols and effects on membrane permeability were found for the R,R-, R,S-, S,S-isomeric complexes. It is proposed that the chirality selectivity in uptake is due to the recognition of the chirality of the platinum complexes by the erythrocyte membrane. The interactions between the chiral platinum complexes and the head groups of the membrane phospholipid molecules are probably involved.

Cell Membrane Permeability↗

PubMed1997

Modification of seed oil content and acyl composition in the brassicaceae by expression of a yeast sn-2 acyltransferase gene.

A putative yeast sn-2 acyltransferase gene (SLC1-1), reportedly a variant acyltransferase that suppresses a genetic defect in sphingolipid long-chain base biosynthesis, has been expressed in a yeast SLC deletion strain. The SLC1-1 gene product was shown in vitro to encode an sn-2 acyltransferase capable of acylating sn-1 oleoyl-lysophosphatidic acid, using a range of acyl-CoA thioesters, including 18:1-, 22:1-, and 24:0-CoAs. The SLC1-1 gene was introduced into Arabidopsis and a high erucic acid-containing Brassica napus cv Hero under the control of a constitutive (tandem cauliflower mosaic virus 35S) promoter. The resulting transgenic plants showed substantial increases of 8 to 48% in seed oil content (expressed on the basis of seed dry weight) and increases in both overall proportions and amounts of very-long-chain fatty acids in seed triacylglycerols (TAGs). Furthermore, the proportion of very-long-chain fatty acids found at the sn-2 position of TAGs was increased, and homogenates prepared from developing seeds of transformed plants exhibited elevated lysophosphatidic acid acyltransferase (EC 2.3.1.51) activity. Thus, the yeast sn-2 acyltransferase has been shown to encode a protein that can exhibit lysophosphatidic acid acyltransferase activity and that can be used to change total fatty acid content and composition as well as to alter the stereospecific acyl distribution of fatty acids in seed TAGs.

1-Acylglycerol-3-Phosphate O-Acyltransferase↗

PubMed1997

[Effects of specific antibodies against the cell surface protein P1 of streptococcus mutans MT 6R upon adhered streptococci].

The sera and saliva were obtained from BALB/C mice by injection of the cell surface protein P1 and Freud's adjuvant. High antibody titers were showed in the sera and saliva by an enzyme-linked immunosorbent assay. The cells of S. mutans (serotype c, e and f) adhered on saliva-coated hydroxyapatite could be detached by the antibodies of the protein P1 of S. mutans MT 6R including in the sera and saliva (P < 0.05), but the antibodies had no influence on the cells of S. cricetus AHT, S. sobrinus OMZ176, S. sobrinus 6715 and S. rattus BHT (P > 0.05).

Animals↗

PubMed1997

[Effects of different dilution of specific antibodies against the cell surface protein P1 of S. mutans MT 6R upon its adherence].

The sera and saliva were obtained from BALB/C mice by injection of the cell surface protein P1 and Freud's adjuvant. High antibody titers were showed in the sera and saliva by an enzyme-linked immunosorbent assay. Different dilution of the specific antibodies against the protein P1 of S. mutans had different inhibition effects on adhering of S. mutans MT 6R. Adherence of streptococcus mutans MT 6R on saliva-coated hydroxyapatite was reduced significantly by using sera and salivary antibodies in dilution of 1:1, 1:2, 1:4, 1:8, 1:16, 1:32 (P < 0.05).

Animals↗

PubMed1996

Cloning of a cDNA encoding the 21.2 kDa oleosin isoform from Arabidopsis thaliana and a study of its expression in a mutant defective in diacylglycerol acyltransferase activity.

A full-length cDNA clone (pA23) of 832 bp encoding an oleosin from Arabidopsis thaliana was isolated by differential screening of a silique-specific cDNA library with probes prepared from poly(A)+ RNA isolated from developing seeds of wild-type (WT) Arabidopsis and from mutant AS11 with a lesion affecting diacylglycerol acyltransferase (DGAT) activity during embryo development. The encoded protein has a calculated molecular mass of 21.2 kDa, and its amino acid sequence shows strong sequence homology and structural similarity to other known oleosins. Transcription of the oleosin gene during seed development was both reduced and delayed in AS11 compared to WT. However, the level of oleosin protein did not appear to be down-regulated during seed development, and at maturity, the overall level of oleosin protein was similar in both WT and AS11. These findings indicate that regulation of oleosin gene expression is part of a highly complex, and co-ordinated expression of storage lipid biosynthesis and related (oleosin) genes during oilseed development.

Acyltransferases↗

PubMed1996

Establishment of an in-use testing method for evaluating disinfection of surgical instruments using the duck hepatitis B model.

Nosocomial transmission of hepatitis B virus (HBV), associated with interventional procedures, has been attributed to its survival on improperly decontaminated instruments. To date, guidelines for chemical disinfection of potentially contaminated heat-sensitive instruments have been based largely on extrapolation of data from in-vitro disinfectant testing. Direct infectivity testing has not been possible for HBV because of the lack of a practical culture assay or susceptible experimental animal model. In this study the related duck hepadnavirus was used to simulate in-vivo transmission of a HBV during surgery, and to evaluate the effectiveness of 2% glutaraldehyde disinfection of surgical laparoscopes. Multiple laparoscopic liver biopsies were performed on 'biohazardous' duck hepatitis B (DHBV) positive ducks. Laparoscopes were then subjected to different disinfection regimes using 2% glutaraldehyde, and residual infectivity tested by placing their tips into the peritoneal cavities of uninfected four-day-old ducklings. Direct transmission of DHBV occurred in all ducks when laparoscopes were not washed. Rinsing with water lowered the transmission rate to 64% and no infection transmission occurred after 5 min of contact time with the disinfectant. In contrast, previous in-vitro studies had shown complete viral inactivation after a shorter period of disinfection. It is postulated that the longer inactivation time observed in our study may be a result of surface interactions of virus and instrument, interfering with disinfectant access or activity. Tests of instrument surface samples for viral DNA by the polymerase chain reaction (PCR) did not correlate with transmission of virus infection in vivo. PCR is an inappropriate test for evaluating the efficacy of disinfectant action despite its sensitivity. This in use method will allow testing of other decontamination procedures and their effectiveness on more complex surgical instruments.

Animals↗