Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Promotion”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed2001

Overexpressed growth hormone (GH) synergistically promotes carcinogen-initiated liver tumour growth by promoting cellular proliferation in emerging hepatocellular neoplasms in female and male GH-transgenic mice.

BACKGROUND/AIMS: Growth hormone (GH), when overexpressed in male and female GH-transgenic mice, is known to induce liver tumours within 1 year. This study aimed to gain a clearer understanding of the interaction between GH and tumour cells in vivo. METHODS/RESULTS: The carcinogen diethylnitrosomine (DEN) was administered to neo-natal transgenic and non-transgenic mice maintained in a "hepatocarcinogenesis resistant" genetic background (C57BL/6J). Macroscopic, microscopic and liver weight/body weight ratio analyses revealed that carcinogen-induced hepatocarcinogenesis was dramatically accelerated in young GH-transgenic mice compared to non-transgenic counterparts. Image analysis of microscopic hepatocellular neoplasms showed rapidly increasing tumour burdens, and neoplastic foci size over time in young adult GH-transgenic mice. The magnitude of enhanced tumour growth was equivalent in both male and female transgenic mice, whereas much lower and sexually dimorphic tumour growth rates (males>females) were observed in non-transgenic mice treated with DEN. BrdU labelling experiments demonstrated that rapid tumour growth in carcinogen-treated GH-transgenic mice was due to the promotion of cell proliferation in emerging lesions. Tumour cell proliferation in young GH-transgenic mice was 2.6- and 4-fold higher, respectively, than that observed in similar age male and female non-transgenic mice. Interestingly, both GH-transgenic and non-transgenic mice displayed progressively slower tumour growth rates in older animals. CONCLUSION: Overall, GH synergistically promotes carcinogen-induced hepatocarcinogenesis in both sexes of GH-transgenic mice by stimulating tumour cell proliferation.

Animals↗
PubMed2002

Supernatants of stored polymorphonuclear neutrophils exhibit growth-promoting activity in several cell lines: perforin expression in polymorphonuclear neutrophils and its role in down-regulation of growth-promoting activity.

BACKGROUND AND OBJECTIVES: Polymorphonuclear neutrophils (PMNs) play important roles in the host immune defence. This study was performed to identify roles of PMNs other than those already known. MATERIALS AND METHODS: PMNs were separated from the peripheral blood of healthy individuals and stored in vitro for 24 h in the presence or absence of an anti-human Fc receptor (FcR) gamma III antibody, namely, anti-CD16 monoclonal antibody (mAb). Stored supernatants were harvested and incubated with several leukaemia and transformed cell lines for 48 h. The increase in growth rate was assessed by the increase in the amount of 3H-thymidine incorporated into these cells. Expression of perforin on PMNs, which is thought to decrease cell viability, was elucidated by flow cytometry (FCM) analysis. The presence of perforin in the stored supernatants was determined using an enzyme-linked immunosorbent assay (ELISA). A serine protease inhibitor, which is known to block the effect of perforin, was added to the cultures of several leukaemia and transformed cell lines to confirm the effect of perforin in reducing cell viability. RESULTS: Growth promotion of some cell lines cultured with the stored supernatants of PMNs was observed both in the presence and absence of anti-CD16 mAb, which was used as a trigger molecule of PMNs. This was particularly notable in the case of Raji and Daudi (both Burkitt lymphoma) cell lines and Epstein-Barr virus (EBV)-transformed B-lymphoblastoid cell lines (B-LCLs) derived from healthy individuals. Perforin expression was observed in both freshly prepared and stored PMNs, regardless of the presence or absence of anti-CD16 mAb. ELISA also detected perforin in the stored supernatants in both the presence and absence of anti-CD16 mAb. The increase in growth rate was induced in the presence of not only a serine protease inhibitor but also an anti-perforin mAb. CONCLUSIONS: Stored supernatants of PMNs exhibit up-regulation of cell growth in several cell lines; this up-regulation is particularly prominent in B-lineage cell lines. Furthermore, perforin appeared to be expressed on PMNs constitutively and secreted into the extracellular fluid. Results of this study strongly suggest that the growth-promoting activity in supernatants of stored PMNs is partially inhibited by perforin, which is thought to be produced by PMNs themselves.

B-Lymphocytes↗
PubMed2003

Tumour necrosis factor-alpha- vs. growth factor deprivation-promoted cell death: different receptor requirements for mediating nerve growth factor-promoted rescue.

Physiological and pathological aging of the central nervous system (CNS) is characterized by functional neuronal impairments which may lead to perturbed cell homeostasis and eventually to neuronal death. Many toxic events may underlie age-related neurodegeneration. These include the effects of beta amyloid, Tau and mutated presenilin proteins, free radicals and oxidative stress, pro-inflammatory cytokines and lack of growth factor support, which can be individually or collectively involved. Taken individually, these toxicants can induce very diverse cell responses, thus requiring individually targeted corrective interventions upstream of common cell death (apoptotic) pathways. Recent preliminary evidence suggests that the pro-inflammatory cytokine tumour necrosis factor alpha (TNFalpha) and growth factor withdrawal can both activate a common apoptotic pathway in nerve growth factor (NGF)-responsive PC12 cells involving caspase 3, albeit through very distinct upstream pathways: the former through active signalling and the latter through passive or lack of survival signalling. Here, we show that NGF can rescue PC12 cells from both growth factor withdrawal- and TNFalpha-promoted cell death. However, NGF rescue from growth factor withdrawal requires NGF signalling through the high-affinity tyrosine kinase receptor (TrkA), while NGF rescue from TNFalpha-promoted cell death requires NGF signalling through the low-affinity p75NTR receptor. These results strengthen the idea that prevention of age- or pathology-associated neurodegeneration may require varied molecular approaches reflecting the diversity of the toxicants involved, possibly acting simultaneously.

Animals↗
PubMed1984

Defining a bacteriophage T4 late promoter: bacteriophage T4 gene 55 protein suffices for directing late promoter recognition.

The RNA polymerase from bacteriophage T4-infected Escherichia coli, which specifically initiates transcription at phage T4 late promoters, is extensively modified by ADP-ribosylation of core subunits and by binding several virus-encoded subunits. We show here that one of these subunits, the phage T4 gene 55 protein, designated gp55, alone endows unmodified RNA polymerase core enzyme from uninfected E. coli with the ability to selectively initiate transcription at the phage T4 late promoters, without participation by E. coli RNA polymerase o- subunit.

DNA-Directed RNA Polymerases↗
PubMed1995

DNA-strand exchange promoted by RecA protein in the absence of ATP: implications for the mechanism of energy transduction in protein-promoted nucleic acid transactions.

DNA-strand exchange promoted by Escherichia coli RecA protein normally requires the presence of ATP and is accompanied by ATP hydrolysis, thereby implying a need for ATP hydrolysis. Previously, ATP hydrolysis was shown not to be required; here we demonstrate furthermore that a nucleoside triphosphate cofactor is not required for DNA-strand exchange. A gratuitous allosteric effector consisting of the noncovalent complex of ADP and aluminum fluoride, ADP.AIF4-, can both induce the high-affinity DNA-binding state of RecA protein and support the homologous pairing and exchange of up to 800-900 bp of DNA. These results demonstrate that induction of the functionally active, high-affinity DNA-binding state of RecA protein is needed for RecA protein-promoted DNA-strand exchange and that there is no requirement for a high-energy nucleotide cofactor for the exchange of DNA strands. Consequently, the free energy needed to activate the DNA substrates for DNA-strand exchange is not derived from ATP hydrolysis. Instead, the needed free energy is derived from ligand binding and is transduced to the DNA via the associated ligand-induced structural transitions of the RecA protein-DNA complex; ATP hydrolysis simply destroys the effector ligand. This concept has general applicability to the mechanism of energy transduction by proteins.

Adenosine Diphosphate↗
PubMed1993

Cytochrome P450-mediated metabolism of tumour promoters modifies the inhibition of intercellular communication: a modified assay for tumour promotion.

The role of metabolism of tumour promoters on the inhibition of intercellular communication was investigated in a modified V79 metabolic cooperation system. V79 cells, which stably express different rat cytochrome P450 enzymes (CYP1A1, CYP1A2 or CYP2B1), were used in the metabolic cooperation assay. The inhibitory effect on intercellular communication of four compounds was changed in cells expressing cytochrome P450 enzymes, compared to cells without. The phorbol ester TPA and di(2-ethylhexyl)phthalate blocked intercellular communication in all the cell lines tested, but expression of CYP1A1 enzyme reduced the inhibitory activity in these cells. Diethylstilbestrol caused inhibition only with cells containing cytochrome P450 enzymes. In contrast, the benzene metabolite hydroquinone inhibited metabolic cooperation preferentially in cells without cytochrome P450 enzymes. The inhibition of metabolic cooperation by another benzene metabolite, phenol, was not affected by the cytochrome P450 enzymes. The inhibitory activity of several chemicals that have not been tested previously was analysed in the new metabolic cooperation assay. The inhibitory activity of none of these chemicals was affected by cytochrome P450-associated metabolism. 7-Octylindolactam V was as potent as TPA, whereas the related indolactam V was 100-fold less active. The carcinogenic aromatic amine 4-aminobiphenyl, but not its primary metabolite 4-hydroxyaminobiphenyl, inhibited metabolic cooperation. Other known carcinogens, ochratoxin A, aflatoxin B1 and 4-nitrobiphenyl, did not inhibit metabolic cooperation in either V79 cells expressing or cells not expressing cytochrome P450. We conclude that cytochrome P450-associated metabolism plays an important role in the inhibition of gap junctional intercellular communication of some tumour promoters. The modified metabolic cooperation assay presented here is valuable for detecting some inhibitory chemicals which have been 'false negative' in previous assays for gap junctional intercellular communication. The assay also discloses that cytochrome P450 metabolism alters intercellular communication by a mechanism other than metabolism of the exogenous inhibitor.

Animals↗
PubMed1996

Promotional timetables: an exploratory investigation of age norms for promotional expectations and their association with job well-being.

Using data representative of the U.S. working population, this research explores age norms for promotional expectations and assesses whether or not they carry with them psychological consequences. Findings reveal some degree of normativity in promotion expectations during two age brackets of the work life span, and they are consistent across assorted structural features. Normative expectations, however, were not associated with job well-being when other relevant factors were included in the analysis. Current job conditions were most clearly linked to well-being.

Adolescent↗
PubMed1991

Ethylene Promotes Elongation Growth and Auxin Promotes Radial Growth in Ranunculus sceleratus Petioles.

Submergence induces elongation in the petioles of Ranunculus sceleratus L., after a rise in endogenous ethylene levels in the tissue. Petioles of isolated leaves also elongate 100% in 24 hours when treated with ethylene gas, without a change in the radius. Application of silver thiosulfate, aminoethoxyvinylglycine (AVG), abscisic acid (ABA), or methyl jasmonate inhibits this elongation response. Gibberellic acid treatment promotes ethylene-induced elongation, without an effect on the radius. Indoelastic acid (IAA) induces radial growth in the petioles, irrespective of the presence or absence of added ethylene. High concentrations of IAA will also induce elongation growth, but this is largely due to auxin-induced ethylene synthesis; treatment with silver thiosulfate, AVG, ABA, or methyl jasmonate inhibit this auxin-promoted elongation growth. However, the radial growth induced by IAA is not affected by gibberellic acid, and not specifically inhibited by ABA, methyl jasmonate, silver thiosulfate, or AVG. These results support the idea that petiole cell elongation during "accommodation growth" can be separated from radial expansion. The radial expansion may well be regulated by IAA. However, effects of high levels of IAA are probably anomalous, since they do not mimic normal developmental patterns.

Journal Article↗
PubMed1998

Gibberellins promote flowering of arabidopsis by activating the LEAFY promoter

The gibberellin class of plant hormones has been implicated in the control of flowering in several species. In Arabidopsis, severe reduction of endogenous gibberellins delays flowering in long days and prevents flowering in short days. We have investigated how the differential effects of gibberellins on flowering correlate with expression of LEAFY, a floral meristem identity gene. We have found that the failure of gibberellin-deficient ga1-3 mutants to flower in short days was paralleled by the absence of LEAFY promoter induction. A causal connection between these two events was confirmed by the ability of a constitutively expressed LEAFY transgene to restore flowering to ga1-3 mutants in short days. In contrast to short days, impairment of gibberellin biosynthesis caused merely a reduction of LEAFY expression when plants were grown in long days or with sucrose in the dark. As a first step toward identifying other small molecules that might regulate flowering, we have developed a rapid in vitro assay for LEAFY promoter activity.

Journal Article↗
PubMed1990

lck suppresses gene expression from various promoters including human T-cell leukemia virus type I promoter.

The T-lymphocyte-specific tyrosine kinase gene, lck, is expressed in T-lymphocyte cell lines, except for several human T-cell leukemia virus type I(HTLV-I)-transformed T-lymphocyte cell lines, which produce HTLV-I. By introducing an lck-expression vector, we found that lck product suppresses gene expression from HTLV-I promoter in a transient assay. Moreover, various other promoters of cellular genes or viruses were found to have their transcriptional activity repressed by lck.

Chloramphenicol O-Acetyltransferase↗
PubMed2006

Prenatal genetic testing kits sold at your local pharmacy: promoting autonomy or promoting confusion?

Research groups around the world are developing non-invasive methods of prenatal genetic diagnosis, in which foetal cells are obtained by maternal blood test. Meanwhile, an increasing number of genetic tests are sold directly to the public. I extrapolate from these developments to consider a scenario in which PNGD self-testing kits are sold directly to the public. Given the opposition to over-the-counter genetic tests and the continuing controversy surrounding PNGD, it is reasonable to expect objections to PNGD self-testing kits. I focus on one potential objection, that PNGD self-testing kits would undermine the autonomy of potential test subjects. More specifically, that 'direct to the public' PNGD would fail to ensure that consumers exercise authority in the following PNGD-related choices: Should I use PNGD? Based on the results of the PNGD test, should I continue or terminate my pregnancy? Under the current system, PNGD is provided by health care practitioners, who are required to counsel women both before and after the test. In contrast, 'direct to the public' PNGD would allow women to make their PNGD-related decisions outside the context of the health care system. I compare these two decision-making contexts, arguing that the health care system is not unequivocally better at promoting the autonomy of potential test subjects. Therefore the promotion of autonomy does not constitute a strong argument against such test kits. Other objections may be more persuasive, so I do not offer an overall assessment of the acceptability of 'direct to the public' PNGD.

Abortion, Eugenic↗
PubMedDate not supplied

Effects of biologically active tumour-promoting and non-promoting phorbol esters on in vitro growth of melanocytic cells.

Sapintoxin A (SAP A), a naturally occurring biologically active but non-promoting phorbol ester, acts as an effective in vitro mitogen for freshly derived human melanocytes. Seven days after addition of 50 nM SAP A there was a four to fivefold increase in melanocyte number over that observed in untreated control cultures comparable to that achieved with a 50 nM concentration of 12-0-tetradecanoylphorbol 13-acetate (TPA). The fluorescent stage 2 promoter sapintoxin D (SAP D) also supported the growth of these cells, with a 50 nM dose producing an increase in cell number comparable to that observed with 200 nM TPA. Similar results were obtained with an established, but non-tumorigenic, line of murine melanocytes. The same compounds exerted a potent anti-proliferative effect against transformed melanocyte lines of murine and human origin associated with morphological alterations and an increase in melanin production consistent with induced cytodifferentiation.

Cell Division↗
PubMed1991

Induction of Epstein-Barr virus lytic cycle by tumor-promoting and non-tumor-promoting phorbol esters requires active protein kinase C.

Exposure to the tiglian 12-O-tetradecanoylphorbol-13-acetate (TPA) represents one of the most efficient and widely used protocols for inducing Epstein-Barr virus (EBV)-infected cells from latent into lytic cycle. Since TPA is both a potent tumor promoter and a potent activator of the cellular protein kinase C (PKC), we sought to determine whether either of these activities was closely linked to EBV lytic cycle induction. A panel of TPA structural analogs, encompassing tiglians with different spectra of biological activities, was assayed on a number of EBV-positive B-lymphoid cell lines. Lytic cycle induction correlated with the capacity to activate PKC, not with tumor promoter status; some nonpromoting tiglians were as efficient as TPA in inducing lytic cycle antigen expression. We then sought more direct evidence for an involvement of PKC in the induction process. In initial experiments, 1-(5-isoquinolinyl sulphonyl)-2-methylpiperazine (H-7), the best available pharmacological inhibitor of PKC, completely blocked the induction of the lytic cycle by TPA and its active analogs. This is consistent with, but does not prove, a requirement for active PKC in the induction process, since H-7 targets PKC preferentially but also has some effects on other kinases. We therefore turned to the synthetic pseudosubstrate peptide PKC(19-36) as a means of specific PKC inhibition and to the closely related but inactive peptide PKC(19-Ser-25-36) as a control. Using the technique of scrape loading to deliver the peptides into cells of an adherent EBV-positive target line, we found that the pseudosubstrate peptide PKC(19-36) completely and specifically blocked tiglian-induced entry of the cells into the lytic cycle. The evidence both from TPA analogs and from enzyme inhibition studies therefore indicates that the pathway linking TPA treatment to lytic cycle induction involves active PKC. Interestingly, inhibition of PKC had no effect upon the spontaneous entry into lytic cycle which occurs in naturally productive cell lines, suggesting that spontaneous entry is signalled by another route.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMedDate not supplied

Aspirin shares a short-term effect, inhibition of pyruvate kinase activity with tumor-promoting agents, but fails to promote rat liver carcinogenesis.

Since aspirin was found to cause a persistent decrease in pyruvate kinase activity, which is a prominent characteristic of the hepatic promoters, the effect of aspirin on hepatic tumorigenesis in the rat has been studied. Male Wistar rats were initiated with a diet containing 0.06% 3'-methyl-4-dimethylamino-azobenzene for 4 weeks. They were divided into 3 groups and each group was fed one of the following diets containing either 0, 0.5 or 1% aspirin. At the end of a 58-week experimental period, no differences were observed in the incidence of hepatic lesions and hepatocellular carcinomas among the groups. Thus, it was concluded that aspirin does not promote nor inhibit the postinitiation step of hepatic tumorigenesis in the rat.

Animals↗
PubMed1995

Inhibitory effect of natural carotenoids on Epstein-Barr virus activation activity of a tumor promoter in Raji cells. A screening study for anti-tumor promoters.

As a screening study for anti-tumor promoters, 51 carotenoids with diverse structures were examined for their inhibitory effects on the Epstein-Barr virus activation activity of 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. The results showed that most of the carotenoids exhibited inhibitory activity, and in general, no cytotoxicity on Raji cells was observed in the assay. Among the carotenoids, beta-cryptoxanthin, lutein, and lactucaxanthin showed the strongest inhibitory activity, superior to the well known anti-tumor promoter, beta-carotene. Heteroxanthin, peridinin, and halocynthiaxanthin showed cytotoxicity at the high concentration (1000 molar ratio per TPA), but indicated a strong inhibitory effect at the lower concentrations, which were only weakly toxic (500 and 100 molar ratios). Based on these results, the essential moiety for the activity of carotenoids was considered to be the 3-hydroxy-epsilon-end group.

Antineoplastic Agents, Phytogenic↗
PubMed1990

Studies on the antitumor-promoting activity of naturally occurring substances. II. Inhibition of tumor-promoter-enhanced phospholipid metabolism by umbelliferous materials.

Ninety-five extracts prepared from 14 kinds of Umbelliferous materials were studied to determine their effects on tumor-promoter-induced phenomena in vitro. Of the materials, 5 Chinese crude drugs, two Bai-Hua Qian-Hu classified as Q-I and Q-II types, the root of Peucedanum praeruptorum Dunn., Zi-Hua Qian-Hu, the root of P. decursivum Maxim., Tang-Bai-Zhi, the root of Angelica dahurica Benth, et Hook. var. pai-chi Kimura, Hata et Yen., Dang-Gui, the root of A. acutiloba Kitagawa and 2 Umbelliferous plants, ashita-ba. A. keiskei Koidz., and ama-nyuu, A. edulis Miyabe, showed potent inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated 32Pi incorporation into phospholipids of cultured cells. From the active fraction of the crude drug "Tang-Bai-Zhi," imperation (1), isoimperatoin (2), oxypeucedanin (3), pabulenol (4), neobyakangelicol (5) and byakangelicin (6) were identified as active or inactive principles. Compound 4 had not previously been isolated from Tang-Bai-Zhi, A. dahurica var. pai-chi. We also discuss the structure-activity relationship among the above 6 kinds of linear-type furanocoumarins, together with 3 kinds of antitumor-promoter coumarins having the same skeleton, psoralen (7), bergapten (8) and xanthotoxin (9), obtained from "ashita-ba" (eaten as a vegetable in Japan). Among the compounds in the present experiment, compounds 1 and 2 showed potent inhibitory activity at the concentration of 50 micrograms/ml and 3-9 were found to have less or no activity.

Animals↗
PubMed1992

Studies on inhibitors of skin tumor promotion. XI. Inhibitory effects of flavonoids from Scutellaria baicalensis on Epstein-Barr virus activation and their anti-tumor-promoting activities.

To search for possible anti-tumor-promoters, fourteen flavones obtained from the root of Scutellaria baicalensis were examined for their inhibitory effects on the Epstein-Barr virus early antigen (EBV-EA) activation by a short-term in vitro assay. Among these flavones, 5,7,2'-trihydroxy- and 5,7,2',3'-tetrahydroxyflavone showed remarkable inhibitory effects on the EBV-EA activation, and the effect of the latter on Raji cell cycle was also examined by flow cytometer. These two flavones exhibited remarkable inhibitory effects on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test.

Animals↗