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Biomedical subjects

P Zhou

Publications and source records attributed to P Zhou.

At least 145 records · Page 8Linked to original sources
PubMed1996

Overexpression of cyclin E in the HC11 mouse mammary epithelial cell line is associated with growth inhibition and increased expression of p27(Kip1).

To elucidate the role of cyclin E in cell growth and tumorigenesis in mammary epithelial cells, we have used retrovirus-mediated transduction to generate derivatives of the nontransformed HC11 mouse mammary epithelial cell line that stably express a human cyclin E cDNA (HU4). These derivatives expressed two distinct forms of the exogenous cyclin E protein, which were about M(r) 50,000 and M(r) 42,000, thus corresponding to endogenous cyclin E proteins found in human cells. In contrast to results obtained previously in fibroblasts, overexpression of the HU4 cyclin E cDNA in HC11 cells was associated with an increase in cell size, lengthening of G(1), and inhibition of both anchorage-dependent and independent growth. Furthermore, when quiescent serum-starved cells were restimulated with serum, entry into the S-phase was delayed in the overexpressor cells. Under these conditions, there was also delayed induction in the expression of the endogenous cyclin E protein and in other events involved in the G(1) transition. Despite the high level of expression of the exogenous cyclin E, the derivatives did not display increased cyclin E-associated in vitro kinase activity. The HC11 cells that overexpressed the exogenous cyclin E displayed an increase in the cyclin/cyclin-dependent kinase inhibitor p27(Kip1) in both asynchronous exponentially dividing and synchronous cell populations. These findings indicate that increased expression of this cyclin E cDNA in HC11 cells inhibits rather than stimulates growth and that this may be due to increased expression of the inhibitor p27(Kip1).

Animals↗
PubMed1996

Overexpression of cyclin D1 enhances gene amplification.

Defects in cell cycle control and increased genomic instability, including gene amplification, often occur during cancer development. Cyclin D1 plays a pivotal role in G1, and this gene is frequently amplified and overexpressed in several types of human cancer. This study demonstrates that ectopic overexpression of cyclin D1 in a rat liver epithelial cell line markedly increased the yield of cells containing amplified copies of the CAD gene. This effect was associated with a loss of G1-S checkpoint control, although the cyclin D1-overexpressing cells had a normal p53 gene. The capacity of cyclin D1 to enhance gene amplification may contribute to the process of genomic instability during tumor development.

Animals↗
PubMed1996

Activation of alveolar macrophage TNF and MCP-1 expression in vivo by a synthetic peptide of C-reactive protein.

Administration of multilamellar vesicles (MLV) encapsulating a synthetic peptide (RS-83277) derived from human C-reactive protein (CRP) augments anti-tumor activity of murine alveolar macrophages and reduces established pulmonary metastases of experimental tumors. To explore mechanisms involved in these phenomena, we investigated cytokine and integrin (CDllb) expression of bronchoalveolar lavage (BAL)-derived alveolar macrophages in control (blank MLV) and RS-83277-MLV-treated C57BI mice. Alveolar macrophage production of tumor necrosis factor alpha (TNF-alpha) and monocyte chemoattractant bioactivity increased at 48 h after treatment with RS-83277-MLV but not control MLV. Chemoattractant activity was neutralized by antibody to monocyte chemoattractant protein-1 (MCP-1), but not irrelevant immunoglobulin G(IgG). Changes were reflected by augmented TNF-alpha and MCP-1 mRNA levels in pulmonary tissue and enhanced CD11b expression on mononuclear leukocytes derived from total lung tissue, but not on BAL-derived alveolar macrophages. Results suggest that RS-83277-MLV treatment is associated with activation of alveolar macrophage TNF-alpha and MCP-1 production and up-regulation of adhesion molecules on pulmonary mononuclear leukocytes but not on alveolar macrophages.

Amino Acid Sequence↗
PubMed1996

Bacterial enzymes can add galactose alpha 1,3 to human erythrocytes and creates a senescence-associated epitope.

Humans have abundant circulating anti-alpha (1,3-di)-galactosyl (alpha Gal) antibodies (anti-Gal). Anti-Gal has been implicated in the clearance of senescent human erythrocytes (RBCs). The nature of the anti-Gal-binding RBC epitope has defied explanation, given that humans repress expression of the alpha 1,3 galactosyltransferase (alpha 1,3 GT) enzyme. This study explored whether alpha Gal epitopes on human RBCs might be synthesized by alpha 1,3 GTs of bacterial origin that are translocated into the circulation during commensal colonization of the gut by gram-negative bacteria. We found that an acellular Klebsiella pneumoniae sonicate could add 3H-UDP-Gal to human RBCs in the alpha configuration at 37 degrees C in the presence of 6 mM MnCl2 (pH 7.6). Gradient anion-exchange chromatography of the Klebsiella sonicate yielded four fractions that could catalyze the addition of 3H-Gal to human RBCs. Size-exclusion chromatography of these anion-exchange fractions yielded peaks of high GT activity for each, but only those derived from the first, third, and last anion-exchange fractions incorporated Gal such that the RBCs bound anti-Gal by fluorescence-activated cell sorter, suggesting that these three GTs are alpha 1,3 GTs. Thus, Klebsiella spp. make at least four GTs that can add an alpha Gal to human cell surface acceptor structures. Three of these GTs can form alpha 1,3 Gal structures on human RBCs that bind anti-Gal, thereby creating "autoimmune" senescence-associated RBC epitopes.

Bacteria↗
PubMed1996

[Effects of shade of visible light cured composites on their polymerization]

Conversion degree of double bonds,microhardness and cure depth of different shade of two visible light cured composites were inspected by means of the Fourier transform infrared spectroscopy and other techniques.The results showed that polymerization in the deep of visible light cured composites was significantly affected by shade of resins.The cure uniformity and the cure depth of darker resins were lower than those of lighter ones.

Journal Article↗
PubMed1996

A one-hand operation gun for transrectal prostate biopsy.

OBJECTIVE: To develop a new automatic biopsy device (ABD) that enables a radiologist to obtain multiple samples with one hand and free the other hand to handle the ultrasonic scanner for continuous monitoring. MATERIALS AND METHODS: The new ABD developed by us in April 1994 enabled a radiologist to complete all the biopsy procedures including loading and reloading the spring system, firing the device, emptying the specimen, selecting the depth of needle advancement, and multiple sampling, simply by pressing 3 buttons in turn with his/her right thumb. Using this new ABD, transrectal prostate biopsy under the guidance of transrectal ultrasonic imaging was performed in 60 consecutive cases of prostate diseases. Each biopsy procedure was completed by a single radiologist, who was able to obtain multiple specimens with one biopsy needle, using only one hand and freeing the other hand for the manipulation of the ultrasonic scanner for guidance. RESULTS: A total of 265 satisfactory core tissue specimens of 285 needle passes (93%) were obtained from the 60 patients. Definite pathologic diagnoses were made for all the 60 patients (100%). No serious biopsy-related complications were observed. The main complications were hematuria in 24 of 60 (40%) patients and fever in 5 (8.3%). CONCLUSION: On the basis of our experience with the 60 patients, this new ABD can be operated smoothly and effectively with the right hand, while the left hand is freed to handle the ultrasonic transducer for continuous monitoring.

Biopsy, Needle↗
PubMed1996

[Detection of konjac glucomannan in seven Amorphophallus Blume species].

Seven Amorphophallus species were detected for konjac glucomananam (KGM). It has been found out that A. albus, A. konjac, A. yuloensis, A. xemengensis and A. dunnii are of higher contents of KGM (30%), but A. sinensis and A. yunnanensis are not as further comfirmed by TLC analysis. It follows that A. albus, A. konjac, A. yuloensis, A. xemengensis and A. dunnii are high quality resources of KGM, but A. sinensis and A. yunanensis cannot be used as substitutes for the above-cited five species.

Chromatography, Thin Layer↗
PubMed1995

Noncovalent protein--oligonucleotide interactions monitored by matrix-assisted laser desorption/ionization mass spectrometry.

Positive ion mode matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was used to explore nonspecific interactions between proteins and oligonucleotides. The formation of noncovalent complexes showed correlation with the type of oligonucleotide bases and with the amino acid composition of the proteins. Among the four DNA homooligomers, abundant protein-nucleic acid complexes were detected for pd(T)n, whereas negligible attachment was evident for pd(A)n, pd(C)n, and pd(G)n. Mixed base sequence nucleic acids (pd(AGCTCAGCTT) and d(TTAGCAGCTT) also showed affinity to Arg-Lys. The protein affinity of pd(T)n turned out to be nonspecific and produced a larger variety of complexes when the number of basic residues in the protein was increased. Complexation of pd(T)n with small basic dipeptides (Arg-Lys or His-His) led to significant improvement in the mass resolution for positive ions. For example, the mass resolution of the pd(T)20/Arg-Lys complex exhibited about 4 times improvement over pd(T)20 alone. The protein--oligonucleotide interactions were also pH and matrix dependent. Lowering the pH from its original value (pH = 1.7) led to diminishing complex related signal, whereas increasing the pH resulted in the appearance of a larger variety of complexes. 2,5-Dihydroxybenzoic acid matrix demonstrated much greater tendency to produce complex ions than did the three other matrix materials we tested. A possible explanation of the observed phenomena was based on pH-controlled ion pair formation between oligonucleotides and proteins.

Acid-Base Equilibrium↗
PubMed1995

The specificity of the transforming growth factor beta receptor kinases determined by a spatially addressable peptide library.

Type I and II receptors for the transforming growth factor beta (TGF-beta) are transmembrane serine/threonine kinases that are essential for TGF-beta signaling. However, little is known about their in vivo substrates or signal transduction pathways. To determine the substrate specificity of these kinases, we developed combinatorial peptide libraries synthesized on a hydrophilic matrix that is easily accessible to proteins in aqueous solutions. When we subjected these libraries to phosphorylation by the cAMP-dependent protein kinase, we obtained the optimal peptide sequence RRXS (I/L/V), in perfect agreement with the substrate sequence deduced from mutagenesis and crystal structure analyses. By using the same libraries, we showed that the optimal substrate peptide for both the type I and II TGF-beta receptors was KKKKKK(S/T)XXX. Since the two kinases are thought to play different roles in intracellular signal transduction, it was a surprise to find that they have almost identical substrate specificity. Our method is direct, sensitive, and simple and provides information about the kinase specificity for all the amino acid residues at each position.

Activin Receptors, Type I↗
PubMed1995

Antisense to cyclin D1 inhibits growth and reverses the transformed phenotype of human esophageal cancer cells.

The cyclin D1 gene is amplified and overexpressed in a significant fraction of human esophageal tumors, and several other types of human cancer, but the functional significance of this overexpression has not been established. To further address the roles of cyclin D1 in growth control and tumorigenesis, we have overexpressed an antisense cyclin D1 cDNA construct, either constitutively or inducibly, in the HCE7 human esophageal cancer cell line in which cyclin D1 is amplified and expressed at high levels. The expression of antisense cyclin D1 led to decreased expression of cyclin D1 at both mRNA and protein levels, and this was associated with a marked inhibition of cell proliferation. Antisense cyclin D1 expressing cells displayed a decreased plating efficiency, increased doubling time, decreased saturation density, increased cell size, decreased cyclin D1-associated in vitro kinase activity, decreased anchorage-independent growth, and a loss of tumorigenicity in nude mice. These findings provide direct evidence that the overexpression of cyclin D1 in certain tumor cells contributes to their abnormal growth and tumorigenicity. The ability to revert the transformed phenotype of these cells with antisense cyclin D1 suggests that cyclin D1 may be a useful target in cancer therapy.

Cell Adhesion↗
PubMed1995

IL-12 prevents mortality in mice infected with Histoplasma capsulatum through induction of IFN-gamma.

Histoplasma capsulatum is a pathogenic fungus found in discrete geographic locations throughout the world. The fungus invades the reticuloendothelial organs such as the spleen and liver of immunocompetent hosts where it is usually controlled. However, in individuals with immune deficiency, histoplasmosis is a severe and potentially fatal disease. Resistance to this infection is due primarily to a cellular immune response mediated by T cells and macrophages. Moreover, IFN-gamma is critical in activating macrophages to kill the organism. Herein we study the regulation of cytokine induction in mice infected with H. capsulatum and the effects of IL-12 in the course of infection. Mice infected with H. capsulatum and treated with neutralizing Abs to IFN-gamma, TNF-alpha, or IL-12 experienced accelerated mortality, indicating that endogenous production of these cytokines plays an important role in response to infection. In contrast, mice treated with IL-12 or a neutralizing Ab to IL-4 at the initiation of infection had substantially diminished mortality. Moreover, mice infected and treated with IL-12 show a two- to threefold increase in the amount of IFN-gamma following in vitro stimulation with specific H. capsulatum Ag compared with the control infected mice. The protective effect of IL-12 could be abrogated if a neutralizing Ab to IFN-gamma was given at the same time, demonstrating that the role of IL-12 in protection was mediated by IFN-gamma. Additionally, infected mice treated with IL-12 had a severalfold decrease in the colony counts of H. capsulatum in spleen cells after 5 days of infection as compared with control animals. Lastly, spleen cells from infected animals treated with IL-12 showed a striking decrease in their proliferative response to mitogen or H. capsulatum Ag. Responses could be restored by adding inhibitors of IFN-gamma or of nitric oxide to the in vitro cultures. The above observations suggest that IL-12 may be useful in immunologic intervention against this opportunistic pathogen.

Animals↗
PubMed1995

Lymphoid enhancer factor 1 directs hair follicle patterning and epithelial cell fate.

T cell-specific transcription factor (TCF-1) and lymphoid enhancer factor 1 (LEF-1) have been implicated exclusively in the regulation of T cell-specific genes. The only adult tissue other than thymus known to express these factors is spleen and lymph node, which contain low levels of LEF-1 and no TCF-1. We noticed that genes involved in hair-specific gene expression possess LEF-1/TCF-1 consensus motifs located in similar positions relative to their TATA box. We show that of the two factors only LEF-1 is expressed in hair follicles; it can be cloned in both splice forms from human skin keratinocytes and it can bind to these sites in the hair promoters. We show that LEF-1 mRNA is present in pluripotent ectoderm, and it is up-regulated in a highly restricted pattern just before the formation of underlying mesenchymal condensates and commitment of overlying ectodermal cells to invaginate and become hair follicles. New waves of ectodermal LEF-1 spots appear concomitant with new waves of follicle morphogenesis. To test whether LEF-1 patterning might be functionally important for hair patterning and morphogenesis, we used transgenic technology to alter the patterning and timing of LEF-1 over the surface ectoderm. Striking abnormalities arose in the positioning and orientation of hair follicles, leaving a marked disruption of this normally uniform patterning. This provides the first direct evidence that ectodermal cues are critical in establishing these developmental processes, which at later stages are known to be influenced by underlying mesenchyme. Remarkably, elevated LEF-1 in the lip furrow epithelium of developing transgenic animals triggered these cells to invaginate, sometimes leading to the inappropriate adoption of hair follicle and tooth cell fates. Collectively, our findings demonstrate that ectodermal expression of LEF-1 plays a central role in gene expression, pattern formation, and other developmental processes involving epithelial-mesenchymal associations.

Alternative Splicing↗
PubMed1995

Combined synthetic/CD strategy for the preparation and configurational assignments of model acyclic 1,3-polyols with a 1,2-diol terminal.

Acyclic 1,3-polyols or skipped polyols are widely distributed in nature. Particularly skipped 1,3-polyols with a terminal 1,2-diol group are present in numerous antifungal polyene macrolides in various masked forms. Although over 200 polyene macrolides are known, the planar structures of only about 40 have been determined, while those for which the full stereochemistry has been elucidated is less than ten. No simple method exists for configurational assignments of the 1,3-polyols moieties; moreover, this class of compounds are difficult to crystallize. In order to develop a general chiroptical method for structure determination of acyclic 1,3-polyols, we have combined a divergent synthetic approach with CD to prepare all possible stereoisomers of 1,2,4-triols, 1,2,4,6-tetrols and 1,2,4,6,8-pentols. The current set of reference polyols should be useful for setting up reference CD libraries and for model studies leading to a general method for configurational assignment of acyclic polyols. This strategy can be used to synthesize further extended members of acyclic 1,3-polyols and mixed 1,2/1,3-polyols which can be used for structural investigations of polyene macrolides and related compounds.

Circular Dichroism↗
PubMed1995

Human monocytes produce monocyte chemoattractant protein 1 (MCP-1) in response to a synthetic peptide derived from C-reactive protein.

We reported previously that a synthetic peptide (RS-83277) derived from human C-reactive protein (CRP) augmented human monocyte/macrophage tumoricidal activity and cytokine production. RS-83287, a synthetic peptide derived from a different CRP site, was ineffective. Because chemoattractant properties have been attributed to some CRP-derived peptides, we hypothesized that RS-83277, in addition to activating effects, might promote human monocyte chemotaxis. Results indicated that neither CRP peptide RS-83277 nor RS-83287 was, itself, a chemoattractant. RS-83277, but not RS-83287, however, elicited time-dependent production of monocyte chemoattractant activity in conditioned media (CM) of cultured human mononuclear leukocytes and purified, adherent monocytes (MO). CM from nonadherent MO contained no activity, indicating that adherence was required for monocyte response. Monocyte chemoattractant activity was dose-dependent and was removed by treatment with immobilized antibody to human monocyte chemoattractant protein 1 (MCP-1) but not by irrelevant IgG. These results indicate that a specific peptide segment of CRP acts upon human adherent monocytes to promote production of the autocrine chemotactic and activating factor MCP-1. Data suggest that degraded CRP represents a complex source of biologically active peptides which, among other effects, may amplify monocyte recruitment to sites of injury.

C-Reactive Protein↗
PubMed1995

Human astrocyte growth regulation: interleukin-4 sensitivity and receptor expression.

We previously reported that interleukin-4 (IL-4) inhibited proliferation of a human astrocytic cell line derived from non-neoplastic adult cortex. To determine whether this effect was receptor-associated and/or limited to only non-neoplastic astrocytes, we examined IL-4 responsiveness and receptor expression in human astrocytic cell lines derived from three different sources: non-neoplastic cerebral cortex (lines P1N, P2N, W3N); neoplastic low grade astrocytoma (LGA) (lines FRLGA, RTLGA); and highly malignant glioblastoma multiforme (GBM) (lines STTG1, CRTG2, WITG3, RUTG4). All lines except RUTG4 GBM expressed IL-4 receptor mRNA. Proliferation and DNA synthesis were markedly suppressed by IL-4 in a dose- and time-dependent manner in all non-neoplastic astrocyte and LGA lines, but not (0/4) GBM. This negative growth-regulatory effect of IL-4 was blocked by specific antibody to human IL-4 receptor but not by irrelevant IgG. In contrast, IL-4 stimulated interleukin-6 (IL-6) secretion in non-neoplastic astrocytes and LGA as well as in GBM cells expressing IL-4 receptor; secretion was undetectable in RUTG4 GBM which did not express receptor. These results indicate that: (i) responsiveness to IL-4 occurs in both non-neoplastic and neoplastic human astroglia; (ii) responsiveness is associated with IL-4 receptor expression; and (iii) sensitivity to negative growth signalling by IL-4 occurs selectively in astrocytes from non-neoplastic cortex or low grade neoplasia but not from highly malignant GBM.

Astrocytes↗