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Biomedical subjects

C M Payne

Publications and source records attributed to C M Payne.

At least 37 records · Page 2Linked to original sources
PubMed1999

Bile salt activation of stress response promoters in Escherichia coli.

Bile salts are prevalent in the mammalian intestine, a natural habitat of Escherichia coli. The bile salts deoxycholate, chenodeoxycholate, ursodeoxycholate, and glycocholate were tested for their effect on induction of 13 specific stress response genes. The most consistently activated E. coli promoters were those for genes micF, osmY, and dinD. MicF and osmY gene products are associated with membrane functions and are responsive to oxidative stress. DinD is induced by DNA damage as part of the SOS response. These results indicate that bile acids, to which E. coli are naturally exposed, induce expression of specific stress response genes, possibly in response to membrane perturbation, oxidative stress, and DNA damage. Altered expression of stress-response genes may also promote interaction of E. coli with cells of the colonic epithelium.

Bacterial Proteins↗
PubMed1999

Manipulating large genomic clones via in vivo recombination in bacteria.

Transgenesis is proving to be a powerful technique in studying the molecular genetics of hypertension. The ability to target specific mutations resulting in either loss of function, by gene deletion, the insertion of reporter sequences, or the subtle change of function by nucleotide replacement, can facilitate the understanding of gene function and its role in the manifestation of diseases. However an inherent problem associated with transgenic studies is the lack of consistent expression observed between independent lines of animals which have integrated the same transgene, a phenomenon known as 'position effect'. Small transgenes are almost invariably subject to position effect due to the absence of essential regulatory elements required to maintain an open chromatin structure. This phenomenon may be overcome if larger transgenes, isolated using vectors such as yeast artifical chromosomes (YACs), bacterial artificial chromosomes (BACs) or P1-based vectors, are used. Studies using such transgenes have reported levels of expression which are consistent between lines and dependent upon the number of copies integrated. The introduction of modifications into these large genomic clones is not practical by traditional restriction endonuclease strategies and so is dependent upon in vivo recombination to maintain structural integrity. Here we demonstrate the modification of a 100 Kb P1 clone spanning the renin locus using the BAC targeting strategy described by Yang et al (Nat Biotechnol 1997; 15: 859-865).

Animals↗
PubMed1999

Reactive nitrogen species in colon carcinogenesis.

The role of reactive nitrogen species (RNS) in colon carcinogenesis is multifactorial and affects diverse processes, such as proliferation, apoptosis, differentiation, tumorigenesis, and metastases. This review describes the stages in colon carcinogenesis where nitric oxide (NO) and inducible NO synthase (NOS2) may influence the progression of a normal mucosa to overt metastatic cancer. Overexpression of NOS2 and an increase in the generation of NO and other RNS may lead to apoptosis resistance, DNA damage, mutation, up-regulation of COX-2, increased proliferation, an increase in oxidative stress and an increase in tumor vascularity and metastatic potential. Therefore, future goals are to establish mechanistically based biomarkers to assess individuals at risk for colon cancer and to implement chemopreventive and dietary strategies that reduce colon cancer risk. An understanding of NO signaling pathways in colon epithelial cells should provide the basis for novel biomarker development. Colon cancer prevention may be achieved effectively by chemically interfering with key components of the NO signaling pathways, changing dietary habits to reduce fat and increase antioxidant-containing vegetables, and dietary supplementation to increase DNA repair.

Animals↗
PubMed1999

Role of nitric oxide and peroxynitrite in bile salt-induced apoptosis: relevance to colon carcinogenesis.

Previous work from our laboratory indicated that the bile salt sodium deoxycholate (NaDOC) induced apoptosis in cultured cells and in normal goblet cells of the colonic mucosa. We also reported that the normal-appearing flat mucosa of patients with colon cancer exhibited apoptosis resistance. Using immunofluorescence in conjunction with confocal microscopy, we now report that high physiological concentrations (0.5 mM) of NaDOC result in the formation of nitrotyrosine residues, a footprint for the formation of reactive nitrogen species, including peroxynitrite, in plasma membrane-associated proteins of HT-29 cells. Because peroxynitrite is formed from the reaction between nitric oxide and superoxide anion, we specifically looked at the role of nitric oxide and superoxide anion in NaDOC-induced apoptosis. Pretreatment of cells with the inhibitor/antioxidants, N-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthase, copper (II) 3,5-diisopropyl salicylate hydrate, a superoxide dismutase mimetic compound, and Trolox, a water-soluble analog of alpha-tocopherol, alone or in combination, sensitized cells to apoptosis induced by 0.5 mM NaDOC. These results suggest that nitric oxide may be part of a signaling pathway that is responsible for apoptosis resistance. The results also indicate that nitric oxide does not appear to protect cells against NaDOC-induced apoptosis by scavenging superoxide anion.

Apoptosis↗
PubMed1998

Inhibitory effect of selenomethionine on the growth of three selected human tumor cell lines.

Selenium supplementation has been shown for many years to work as an anticarcinogenic agent both in epidemiology and in in vitro studies. Selenium supplementation has recently been shown to decrease total cancer incidence. However, the mechanism of action of selenium as an anticarcinogenic agent has yet to be elucidated. Selenomethionine was the predominant form of selenium in the dietary supplement in the study by Clark et al. (Clark, L.C., Combs, G.F., Turnbull, W.B., Slate, E.H., Chalker, D.K., Chow, J., Davis, L.S., Glover, R.A., Graham, G.F., Gross, E.G., Krongrad, A., Lesher, J.L., Park, H.K., Sanders, B.B., Smith, C.L., Taylor, J.R. and The Nutritional Prevention of Cancer Study Group (1996) Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin: a randomized controlled trial. J. Am. Med. Assoc., 276 (24), 1957-1963) and therefore we evaluated the growth inhibitory effects of selenomethionine against human tumor cells. Selenomethionine was tested against each of three human tumor cell lines (MCF-7/S breast carcinoma, DU-145 prostate cancer cells and UACC-375 melanoma) and against normal human diploid fibroblasts. All cell lines demonstrated a dose-dependent manner of growth inhibition by selenomethionine. Selenomethionine inhibited the growth of all of the human tumor cell lines in the micromolar (microM) range (ranging from 45 to 130 microM) while growth inhibition of normal diploid fibroblasts required 1 mM selenomethionine, approximately 1000-fold higher than for the cancer cell lines. In short, normal diploid fibroblasts were less sensitive than the cancer cell lines to the growth inhibitory effects of selenomethionine. Furthermore, we show that selenomethionine administration to these cancer cell lines results in apoptotic cell death and aberrant mitoses. These results demonstrate the differential sensitivity of tumor cells and normal cells to selenomethionine.

Antineoplastic Agents↗
PubMed1998

Special techniques in diagnostic electron microscopy.

The power of electron microscopy as a diagnostic tool can be amplified considerably by the application of ancillary preparative and analytic methods. Subcellular chemistry and structure can be examined by various forms of microprobe analysis and by special staining methods, including cytochemical, immunocytochemical, and negative staining. Qualitative ultrastructural examination can be augmented by morphometric analysis. Correlative microscopic survey methods can be used as a means of targeting ultrastructural investigations. This article provides an overview of the use of these special techniques in the diagnosis and classification of tumors and other selected pathologic processes.

Diagnosis, Differential↗
PubMed1998

The stress-response proteins poly(ADP-ribose) polymerase and NF-kappaB protect against bile salt-induced apoptosis.

Bile salts induce apoptosis and are implicated as promoters of colon cancer. The mechanisms by which bile salts produce these effects are poorly understood. We report that the cytotoxic bile salt, sodium deoxycholate (NaDOC), activates the key stress response proteins, NF-kappaB and poly(ADP-ribose) polymerase (PARP). The activation of NF-kappaB and PARP, respectively, indicates that bile salts induce oxidative stress and DNA damage. The pre-treatment of cells with specific inhibitors of these proteins [pyrrolidine dithiocarbamate (NF-kappaB inhibitor) and 3-aminobenzamide (PARP inhibitor)] sensitizes cells to the induction of apoptosis by NaDOC, indicating that these stress response pathways are protective in nature. Colon cancer risk has been reported to be associated with resistance to apoptosis. We found an increase in activated NF-kappaB at the base of human colon crypts that exhibit apoptosis resistance. This provides a link between an increased stress response and colon cancer risk. The implications of these findings with respect to apoptosis and to colon carcinogenesis are discussed.

Apoptosis↗
PubMed1998

Liposuction for axillary hyperhidrosis.

A 23-year-old woman presented with a 10 year history of excessive sweating (hyperhidrosis), mostly in the axillae, and to a lesser extent the groin and hands. Initial treatment with a sedative antihistamine and topical Driclor (aluminium chloride hexahydrate in 2% alcohol) for 14 weeks resulted in no improvement. Axillary liposuction, a short and simple procedure, then produced a very satisfactory result.

Adult↗
PubMed1998

Different bile acids exhibit distinct biological effects: the tumor promoter deoxycholic acid induces apoptosis and the chemopreventive agent ursodeoxycholic acid inhibits cell proliferation.

Epidemiological studies have suggested that the concentration and composition of fecal bile acids are important determining factors in the etiology of colon cancer. However, the mechanism by which these compounds influence tumor development is not understood. To begin to elucidate their mechanism of action, four bile acids, cholic acid, chenodeoxycholic acid, deoxycholic acid (DCA), and ursodeoxycholic acid, were examined for their effects on the growth of several different tumor cell lines. We found that incubating cells with chenodeoxycholic acid or DCA caused morphological changes, seen by electron and light microscopy, that were characteristic of apoptosis, whereas incubating cells with ursodeoxycholic acid inhibited cell proliferation but did not induce apoptosis. Cholic acid had no discernible effect on cells. Notably, the apoptosis induced by DCA could be suppressed by inhibiting protein kinase C activity with calphostin C. These results indicate that different bile acids exhibit distinct biological activities and suggest that the cytotoxicity reported for DCA may be due to its capacity to induce apoptosis via a protein kinase C-dependent signaling pathway.

Anticarcinogenic Agents↗
PubMed1997

Excess putrescine accumulation inhibits the formation of modified eukaryotic initiation factor 5A (eIF-5A) and induces apoptosis.

DH23A cells, an alpha-difluoromethylornithine-resistant variant of the parental hepatoma tissue culture cells, express high levels of stable ornithine decarboxylase. Aberrantly high expression of ornithine decarboxylase results in a large accumulation of endogenous putrescine and increased apoptosis in DH23A cells when alpha-difluoromethylornithine is removed from the culture. Treatment of DH23A cells with exogenous putrescine in the presence of alpha-difluoromethylornithine mimics the effect of drug removal, suggesting that putrescine is a causative agent or trigger of apoptosis. Accumulation of excess intracellular putrescine inhibits the formation of hypusine in vivo, a reaction that proceeds by the transfer of the butylamine moiety of spermidine to a lysine residue in eukaryotic initiation factor 5A (eIF-5A). Treatment of DH23A cells with diaminoheptane, a competitive inhibitor of the post-translational modification of eIF-5A, causes both the suppression of eIF-5A modification in vivo and induction of apoptosis. These data support the hypothesis that rapid degradation of ornithine decarboxylase is a protective mechanism to avoid cell toxicity from putrescine accumulation. Further, these data suggest that suppression of modified eIF-5A formation is one mechanism by which cells may be induced to undergo apoptosis.

Animals↗
PubMed1997

Thioredoxin, a gene found overexpressed in human cancer, inhibits apoptosis in vitro and in vivo.

The redox protein thioredoxin plays an important role in controlling cancer cell growth through regulation of DNA synthesis and transcription factor activity. Thioredoxin is overexpressed by a number of human primary cancers and its expression is decreased during dexamethasone-induced apoptosis of mouse WEHI7.2 thymoma cells. We examined the ability of WEHI7.2 cells stably transfected with human thioredoxin cDNA showing increased levels of cytoplasmic thioredoxin to undergo apoptosis in vitro and in vivo. The cells were protected from apoptosis induced by dexamethasone, staurosporine, etoposide, and thapsigargin, but not by N-acetyl-sphingosine. When inoculated into severe combined immunodeficient mice, the trx-transfected cells formed tumors that showed increased growth compared to wild-type, as well as bcl-2-transfected, WEHI7.2 cells. The trx- and bcl-2-transfected cell tumors both showed less spontaneous apoptosis than tumors formed by the wild-type cells. Unlike tumors formed by the wild-type and bcl-2-transfected WEHI7.2 cells, trx-transfected cell tumors did not show growth inhibition upon treatment with dexamethasone. This study suggests that increased thioredoxin expression in human cancers may result in an increased tumor growth through inhibition of spontaneous apoptosis and a decrease in the sensitivity of the tumor to drug-induced apoptosis.

Animals↗
PubMed1996

Bile acid activation of the gadd153 promoter and of p53-independent apoptosis: relevance to colon cancer.

Bile acids are strongly implicated in the etiology of colon cancer. Bile acids also induce apoptosis, and this action may be a key to understanding their role in colon cancer. However the mechanism of bile acid induction of apoptosis is not known. We present evidence of bile acid activation of the gadd153 promoter (a promoter activated by DNA damaging agents). We also show that bile acid induction of apoptosis is p53-independent. In addition, bile salts were found to induce blebbing preceding the actual morphological onset of apoptosis, which indicates early cytoskeletal alterations.

Journal Article↗
PubMed1995

Apoptosis overview emphasizing the role of oxidative stress, DNA damage and signal-transduction pathways.

Apoptosis (programmed cell death) is a central protective response to excess oxidative damage (especially DNA damage), and is also essential to embryogenesis, morphogenesis and normal immune function. An understanding of the cellular events leading to apoptosis is important for the design of new chemotherapeutic agents directed against the types of leukemias and lymphomas that are resistant to currently used chemotherapeutic protocols. We present here a review of the characteristic features of apoptosis, the cell types and situations in which it occurs, the types of oxidative stress that induce apoptosis, the signal-transduction pathways that either induce or prevent apoptosis, the biologic significance of apoptosis, the role of apoptosis in cancer, and an evaluation of the methodologies used to identify apoptotic cells. Two accompanying articles, demonstrating classic apoptosis and non-classic apoptosis in the same Epstein-Barr virus-transformed lymphoid cell line, are used to illustrate the value of employing multiple criteria to determine the type of cell death occurring in a given experimental system. Aspects of apoptosis and programmed cell death that are not covered in this review include histochemistry, details of cell deletion processes in the sculpting of tissues and organs in embryogenesis and morphogenesis, and the specific pathways leading to apoptosis in specific cell types. The readers should refer to the excellent books and reviews on the morphology, biochemistry and molecular biology of apoptosis already published on these topics. Emphasis is placed, in this review, on a proposed common pathway of apoptosis that may be relevant to all cell types.

Animals↗
PubMed1995

Evaluation of cell death in EBV-transformed lymphocytes using agarose gel electrophoresis, light microscopy and electron microscopy. I. Induction of classic apoptosis by the bile salt, sodium deoxycholate.

In this study, we examined the effect of different concentrations of sodium deoxycholate (NaDOC), a secondary bile salt, on an Epstein-Barr virus transformed human lymphoid cell line (NC-37). We found that NaDOC induces classic apoptosis in a dose-dependent manner at 0.1-0.4 mM doses, and necrosis at much higher concentrations (0.8-3.1 mM). This is the first demonstration that a bile salt can induce apoptosis in any cell type. The mode of cell death was determined using morphologic methods (light and electron microscopy) as the gold standard. Standard agarose gel electrophoretic techniques were applied to identify the "ladder" of DNA fragments that have been associated with apoptosis in certain cell types. Although DNA fragmentation was observed during the apoptotic death of NC-37 cells, we were not able to identify a "ladder" pattern of fragmentation. Two other types of cells, however, that previously have been reported to display a characteristic "ladder" pattern of DNA fragmentation, glucocorticoid-treated WEHI7.2 cells and isolated human neutrophils, did display the "ladder" pattern. This study emphasizes the need to examine morphology when identifying the mode of cell death induced by a new agent.

Apoptosis↗
PubMed1995

Evaluation of cell death in EBV-transformed lymphocytes using agarose gel electrophoresis, light microscopy and electron microscopy. II. Induction of non-classic apoptosis ("para-apoptosis") by tritiated thymidine.

There is an extensive literature dating back to the late 1950's, on the damaging biological effects of radiolabeling DNA in vivo. Nonetheless, tritiated thymidine has often been used to label DNA in studies of programmed cell death (apoptosis). In the present study, we have investigated the effects of incorporation of tritiated thymidine into the DNA of an Epstein-Barr virus-transformed cell line (NC-37) in the absence of any other apoptosis-inducing agent. Cells were incubated in media containing 1-20 microCi/ml [methyl-3H]-thymidine ([3H]-TdR). At each concentration of tritiated thymidine used, cell proliferation ceased within 12 hours of incubation. The mode of cell death caused by tritiated thymidine incorporation was evaluated using DNA degradation patterns and cellular morphology. DNA degradation, in the absence of a "ladder" pattern, was shown by agarose gel electrophoresis. Electron microscopy was used as the "gold standard" to evaluate the specific morphologic type of cell death that accompanied the DNA degradation. Although some of the features of apoptosis were present, the cells lacked the early margination of the chromatin within an intact nucleus and surface blebbing leading to apoptotic body formation, two characteristic morphological features of apoptosis. We, therefore, coined the term "para-apoptosis" to be more precise about the morphologic type of cell death. The percent of para-apoptotic cells was quantitated by light microscopy using whole mount preparations (cytospins). The morphologic criteria of chromatin condensation, nuclear fragmentation, increase in cell density and cytoplasmic vacuolization were used for the evaluation of para-apoptosis by light microscopy of cytospin preparations. In the absence of tritiated thymidine, < 2% of the cells became apoptotic/para-apoptotic after 43 hours of incubation. However, at all concentrations of tritiated thymidine used in the incubation medium (1-20 microCi/ml), the number of para-apoptotic cells increased. In addition, we detected perturbations in the timing of the cell cycle of the surviving cells and an increase in the number of micronuclei after only one division cycle. The induction of para-apoptosis and micronuclei formation represent two distinct modes of cell death caused by tritiated thymidine incorporation. These studies emphasize the necessity for morphological examination in characterizing the induction of cell death in a new experimental system.

Apoptosis↗
PubMed1994

Programmed cell death of the normal human neutrophil: an in vitro model of senescence.

The present study provides experimental data which indicate that the neutrophil is ideal for studying programmed cell death or apoptosis in vitro. Neutrophils can be obtained from human peripheral blood in large numbers with minimal experimental manipulation and are easily separated from other leukocytes, providing nearly pure cell suspensions. The neutrophil life span in vitro is sufficiently short to allow observations to be made within eight hours after experimental manipulation. Neutrophils can also be easily maintained in serum-free, chemically defined media which can be systematically altered, thereby defining specific variables that influence the apoptotic process. Since the neutrophils do not need an exogenous trigger to undergo programmed cell death, it is also an excellent model to study senescence. It was determined from this study that neutrophils undergo apoptosis most efficiently at 37 degrees C, a temperature requirement for physiologic cell death. Neutrophils undergo apoptosis at a slightly faster rate and maintain membrane integrity better when incubated in a tissue culture medium (e.g., RPMI 1640) compared with a balanced salt solution (e.g., HBBB). Cycloheximide, an inhibitor of protein synthesis, was shown to accelerate apoptosis in a dose-dependent manner. The presence of Zn++ significantly decreased the rate of apoptosis, whereas the presence of Ca++ and Mg++ had no apparent effect. These studies indicate that the process of senescence, culminating in cell death, is subject to modulation by a variety of agents and experimental conditions. In addition, the ultrastructural features of neutrophils undergoing programmed cell death in vitro were compared in detail to those occurring in vivo and were found to be comparable.

Apoptosis↗
PubMed1994

Clinical paths for cardiac surgery patients: a multidisciplinary approach to quality improvement outcomes.

Implementation of clinical paths has resulted in a successful multidisciplinary approach for monitoring quality improvement outcomes in a select group of cardiovascular patients. This article defines clinical paths and explains their development, implementation, and evaluation. It also discusses how variances (which are defined as discrepancies between expected and actual events) were identified and how this information led to actions to improve patient outcomes. The roles of each health care professional are discussed in relation to clinical paths, and positive outcomes for the nurse, other health care professionals, and the institution are presented.

Clinical Protocols↗