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Mehta DV, Kim YS, Dixon D, Jetten AM. Characterization of the expression of the retinoid-related, testis-associated receptor (RTR) in trophoblasts. Placenta 2002; 23:281-7. [PMID: 11969338 DOI: 10.1053/plac.2001.0779] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Previous studies have provided evidence indicating that the nuclear orphan receptor RTR plays an important role during embryonic development and in spermatogenesis. In this study, we examine the expression of RTR in murine placenta and several human placental choriocarcinoma cell lines. Northern blot analysis showed high expression of RTR mRNA in placental tissue. In contrast to murine testis, which contains 7.4 and 2.3 kb transcripts, placental tissue expressed only the larger transcript. Examination of RTR expression in murine placental tissue by immunohistochemistry demonstrated the presence of RTR protein in the nuclei of giant trophoblasts and spongiotrophoblasts. RTR mRNA was also expressed in rat choriocarcinoma Rcho-1 cells and in the human placental choriocarcinoma cell lines BeWo, JAR, and JEG-3. In trophoblasts, RTR was co-expressed with the estrogen-related receptors ERR alpha and ERR beta. Giant trophoblast differentiation in Rcho-1 cells, characterized by induction of placental lactogen I (PL-I), was accompanied by a steady decrease in the expression of RTR mRNA and down-regulation of ERR beta expression while levels of ERR alpha mRNA did not change significantly. RTR was able to inhibit ERR alpha-mediated transactivation through the consensus RTR-response element (RTRE) likely by competing with ERR alpha for binding to the RTRE. These results suggest the possibility of cross-talk between RTR and ERR alpha receptor signalling pathways in trophoblasts.
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MESH Headings
- Animals
- Cell Differentiation
- Cell Line
- Choriocarcinoma/genetics
- Choriocarcinoma/metabolism
- DNA-Binding Proteins
- Female
- Gene Expression
- Humans
- Immunohistochemistry
- Male
- Mice
- Nuclear Receptor Subfamily 6, Group A, Member 1
- Pregnancy
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Receptor Cross-Talk
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, Retinoic Acid/genetics
- Receptors, Retinoic Acid/metabolism
- Testis/metabolism
- Trophoblasts/cytology
- Trophoblasts/metabolism
- Uterine Neoplasms/genetics
- Uterine Neoplasms/metabolism
- ERRalpha Estrogen-Related Receptor
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Dixon D, Martin P, Harkin-Jones E. The Effect of Material Factors on the Density and Cell Morphology of Chemically Foamed Polypropylene. CELLULAR POLYMERS 2001. [DOI: 10.1177/026248930102000603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This paper assesses the effect of various material factors on the cell morphology and density of extruded expanded polypropylene (EPP), rod samples produced using a range of commercial chemical blowing agents (CBAs). This work is part of a research project into the optimisation of the extrusion and subsequent thermoforming of EPP sheet for food packaging applications. In each case the agents were added to PP and extruded under identical processing conditions, and the resulting variations in foam density and cell morphology are reported and discussed. Trials were also carried out to quantify the effects on the foam of additives, such as pigment, sodium benzoate, co-polymer and regrind, and the grade of polymer used (nucleated and un-nucleated). A design of experiment (DOE) methodology was adopted for all of these latter tests. The chemical blowing agents tested, produced foams with markedly different cellular structures with cell densities in the range 4.77×104 to 1.45×106 cells/cm3. Of the other material factors tested the change in polymer grade and the addition of sodium benzoate were found to most significantly affect the density and cell morphology.
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53
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Combs D, Gouvier W, Dixon D. The role of attention in affect perception: an examination of Mirsky's four-factor model of attention in chronic schizophrenia. Arch Clin Neuropsychol 2001. [DOI: 10.1093/arclin/16.8.801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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54
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Couse JF, Dixon D, Yates M, Moore AB, Ma L, Maas R, Korach KS. Estrogen receptor-alpha knockout mice exhibit resistance to the developmental effects of neonatal diethylstilbestrol exposure on the female reproductive tract. Dev Biol 2001; 238:224-38. [PMID: 11784006 DOI: 10.1006/dbio.2001.0413] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Data indicate that estrogen-dependent and -independent pathways are involved in the teratogenic/carcinogenic syndrome that follows developmental exposure to 17beta-estradiol or diethylstilbestrol (DES), a synthetic estrogen. However, the exact role and extent to which each pathway contributes to the resulting pathology remain unknown. We employed the alphaERKO mouse, which lacks estrogen receptor-alpha (ERalpha), to discern the role of ERalpha and estrogen signaling in mediating the effects of neonatal DES exposure. The alphaERKO provides the potential to expose DES actions mediated by the second known ER, ERbeta, and those that are ER-independent. Wild-type and alphaERKO females were treated with vehicle or DES (2 microg/pup/day for Days 1-5) and terminated after 5 days and 2, 4, 8, 12, and 20 months for biochemical and histomorphological analyses. Assays for uterine expression of the genes Hoxa10, Hoxa11, and Wnt7a shortly after treatment indicated significant decreases in DES-treated wild-type but no effect in the alphaERKO. In contrast, the DES effect on uterine expression of Wnt4 and Wnt5a was preserved in both genotypes, suggesting a developmental role for ERbeta. Adult alphaERKO mice exhibited complete resistance to the chronic effects of neonatal DES exposure exhibited in treated wild-type animals, including atrophy, decreased weight, smooth muscle disorganization, and epithelial squamous metaplasia in the uterus; proliferative lesions of the oviduct; and persistent vaginal cornification. Therefore, the lack of DES effects on gene expression and tissue differentiation in the alphaERKO provides unequivocal evidence of an obligatory role for ERalpha in mediating the detrimental actions of neonatal DES exposure in the murine reproductive tract.
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Gerdom LE, Dixon D, Dipalma JA. Hemorrhoids, genital warts, and other perianal complaints. JAAPA 2001; 14:37-9, 43-4, 47. [PMID: 11599281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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56
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Bolto B, Dixon D, Eldridge R, King S. Cationic polymer and clay or metal oxide combinations for natural organic matter removal. WATER RESEARCH 2001; 35:2669-2676. [PMID: 11456166 DOI: 10.1016/s0043-1354(00)00552-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The effect of adding suspended matter in the form of clay or metal oxide when a cationic polymer was employed as the primary coagulant was found to be beneficial. The solids provide both an adsorbent for natural organic matter (NOM) and a nucleating species for precipitating the NOM-polymer complex. Metal oxides in conjunction with a cationic polymer were more promising than clay, with effectiveness in the order Fe2O3 > Fe3O4 > Al2O3 > MnO2. Magnesium oxide at a much lower dose was nearly as effective as ferric oxide, but of course raised the pH level significantly. A simpler and more convenient way of having reactive solids present was to add alum to form flocs; for one of the waters studied the alum dose could be reduced by 67% by adding 1 mg/L of polymer, to give equal or better performance than alum alone at the optimum dose.
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57
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Arai M, Billker O, Morris HR, Panico M, Delcroix M, Dixon D, Ley SV, Sinden RE. Both mosquito-derived xanthurenic acid and a host blood-derived factor regulate gametogenesis of Plasmodium in the midgut of the mosquito. Mol Biochem Parasitol 2001; 116:17-24. [PMID: 11463462 DOI: 10.1016/s0166-6851(01)00299-7] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Gametogenesis of Plasmodium in vitro can be induced by the combined stimulus of a 5 degrees C fall in temperature and the presence of xanthurenic acid (XA). In-vitro experiments showed that P. gallinaceum (EC(50)=80 nM) is much more sensitive to XA than P. berghei (9 microM), P. yoelii (8 microM), and P. falciparum (2 microM). However, in the mosquito vector, we do not know whether the temperature shift and XA are the only gametocyte-activating factors (GAF), nor do we know with certainty the true source(s) of XA in the mosquito blood meal. Previous studies indicate that XA is the only source of GAF in the mosquito. By defining, and then contrasting, the ability of an XA-deficient mutant of Aedes aegypti, with the wild-type mosquito to support exflagellation and ookinete formation in vivo, we determined the roles of parasite-, mosquito- and host blood-derived GAF in the regulation of gametogenesis of P. gallinaceum. Removal of both host and vector sources of GAF totally inhibited both exflagellation and ookinete production, whilst the lack of either single source resulted in only a partial reduction of exflagellation and ookinete formation in the mosquito gut. Both sources can be effectively replaced/substituted by synthetic XA. This suggests (1) both mosquito- and vertebrate-derived factors act as GAF in the mosquito gut in vivo; (2) the parasite itself is unable to produce any significant GAF activity. Studies are underway to determine whether vertebrate-derived GAF is XA. These data may form the basis of further studies of the development of new methods of interrupting malarial transmission.
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Rosengarten P, Kelly AM, Dixon D. Does routine use of the 15-lead ECG improve the diagnosis of acute myocardial infarction in patients with chest pain? EMERGENCY MEDICINE (FREMANTLE, W.A.) 2001; 13:190-3. [PMID: 11482857 DOI: 10.1046/j.1442-2026.2001.00210.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE It has been suggested that the use of additional electrocardiogram leads might improve the diagnostic sensitivity of this test, thus potentially expanding eligibility for thrombolysis for patients suffering myocardial infarction. The aims of this study were to evaluate the role of the 15-lead electrocardiogram in the emergency department chest pain population and to determine whether the routine use of the extra leads expands the group of patients eligible to receive thrombolysis. METHODS Blinded, individual and independent analysis by two emergency physicians of paired 12- and 15-lead electrocardiograms from adult patients with a primary complaint of chest pain. The main outcome measure was the diagnosis of myocardial infarction eligible for thrombolysis. Data were analysed using descriptive statistics and kappa statistics for agreement between raters. RESULTS 540 electrocardiograms (270 sets) were analysed. Myocardial infarction qualifying for thrombolysis was identified (by consensus) in 21 cases. In no case did the 15-lead electrocardiograph identify a myocardial infarction qualifying for thrombolysis that was not identified on the 12-lead electrocardiogram. CONCLUSION In this study, the 15-lead electrocardiogram did not increase the number of thrombolysis-eligible myocardial infarctions identified when compared with the 12-lead electrocardiogram. This study is limited by the small patient sample size, and a large multicentre trial is recommended to compare the 12- and 15-lead electrocardiograms in the emergency department population where the incidence of posterior and right-sided myocardial infarction is ultimately known.
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59
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60
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Dixon D. Children's magazines and science in the nineteenth century. VICTORIAN PERIODICALS REVIEW 2001; 34:228-238. [PMID: 18572490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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61
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Furnham A, Dixon D, Harrison T, Rasmussen S, O'Connor R. Sex, social class, and estimating IQ: middle-class male subjects rate themselves most intelligent. Psychol Rep 2000; 87:753-8. [PMID: 11191383 DOI: 10.2466/pr0.2000.87.3.753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
153 sociology students specified parental occupation and job status before estimating their own and their parents' overall IQ. Male subjects, as predicted, gave a higher mean self-estimated score to themselves than did female subjects (113 vs 106). Fathers were awarded higher IQ scores than mothers (114 vs 107). Male subjects who had mothers in a higher social class gave themselves the highest mean score.
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62
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Leark R, Dixon D, Allen M, Llorente A. Cross-validation of diagnostic hit rates and performance differences between ADHD and normative groups of children on the test of variables of attention (T.O.V.A.). Arch Clin Neuropsychol 2000. [DOI: 10.1093/arclin/15.8.687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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63
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Newbold RR, DiAugustine RP, Risinger JI, Everitt JI, Walmer DK, Parrott EC, Dixon D. Advances in uterine leiomyoma research: conference overview, summary, and future research recommendations. ENVIRONMENTAL HEALTH PERSPECTIVES 2000; 108 Suppl 5:769-773. [PMID: 11035980 DOI: 10.1289/ehp.00108s5769] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Uterine leiomyomas (fibroids, myomas) are the most common tumors occurring in the genital tract of women over 30 years of age. These benign uterine smooth-muscle tumors are estimated to be clinically significant in at least 25% of the American female population during their reproductive years. Furthermore, when thorough pathologic examination of hysterectomy specimens has been performed in patients with or without clinical history of myomatous uteri, the incidence of fibroids is 77%, suggesting that these tumors are far more prevalent than estimated by clinical cases. In spite of their high prevalence, little is known concerning the etiology or the molecular basis of their development and growth. It is well known that leiomyoma growth is regulated by ovarian steroid hormones, yet the exact molecular pathway(s) involved in tumor growth and the role of genetic susceptibility/predisposition and the environment are unclear. This article is an overview of some of the topics addressed at the conference on Women's Health and the Environment: The Next Century--Advances in Uterine Leiomyoma Research. A summary of research needs and recommendations for future research directions based on conference discussions are also presented.
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64
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Dixon D, He H, Haseman JK. Immunohistochemical localization of growth factors and their receptors in uterine leiomyomas and matched myometrium. ENVIRONMENTAL HEALTH PERSPECTIVES 2000; 108 Suppl 5:795-802. [PMID: 11035985 DOI: 10.1289/ehp.00108s5795] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Immunolocalization of transforming growth factor alpha (TGF-Alpha), epidermal growth factor (EGF), insulinlike growth factor (IGF)-I, vascular endothelial growth factor (VEGF(165,189,121)), basic fibroblast growth factor (FGF)-2, EGF receptor (R), IGF-IRbeta, and FGFR-1 was studied in uterine leiomyomas and matched myometrial samples taken from seven women (42-47 years of age) in the proliferative phase of the menstrual cycle. Immunolocalization of growth factor peptides was accomplished with either monoclonal or polyclonal antibodies to the amino or carboxy terminus of growth factor peptides or their respective receptors, or against full-length recombinant growth factor. All reactions were conducted using the avidin-biotin complex method. Immunolocalization of TGF-alpha, EGF, EGF-R, IGF-I, IGF-IRbeta, FGF-2, FGFR-1, and VEGF was observed in the cytoplasm of smooth-muscle cells of leiomyomas and matched myometrium. The cytoplasm of vascular smooth-muscle cells expressed TGF-alpha, EGF, EGF-R, IGF-I, IGF-IRbeta, FGF-2, FGFR-1, and VEGF, whereas the vascular endothelium was positive for TGF-alpha, EGF, EGF-R, FGF-2, and FGFR-1 in both leiomyomas and matched myometria. Fibroblasts within the fibrous component of some leiomyomas were positive for IGF-I and FGF-2 and minimally positive for FGFR-1. In addition, the extracellular matrix of leiomyomas showed focal localization of FGF-2 and IGF-I in some tumors. When scores of intensity and percent positive staining were compared, IGF-IRbeta was significantly increased in the leiomyomas compared to matched myometria, whereas EGF was significantly decreased in the uterine leiomyomas compared to matched myometria. In summary, these data revealed growth factors to be expressed differentially in smooth muscle, vascular and fibroblastic cell types of leiomyomas and matched myometria. Specifically, IGF-IRbeta was significantly increased in leiomyomas; although a similar increase was seen with IGF-I peptide, statistical significance was not achieved. The EGF peptide was significantly decreased in the leiomyomas compared to matched myometrium. These data suggest that IGF-IRbeta and IGF-I peptide may be one of several growth factor/receptor pathways important in uterine leiomyoma growth during the proliferative phase of the menstrual cycle. In addition, decreased EGF may be secondary to the predominant estrogenic milieu present at time of sampling, as it has been proposed that progesterone, and not estrogen, may regulate EGF.
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Moore AB, He H, Yoshida A, Rico PJ, Haseman JK, Dixon D. Transforming growth factor-alpha, epidermal growth factor receptor, and PCNA immunoexpression in uterine leiomyosarcomas and leiomyomas in B6C3F1 mice. EXPERIMENTAL AND TOXICOLOGIC PATHOLOGY : OFFICIAL JOURNAL OF THE GESELLSCHAFT FUR TOXIKOLOGISCHE PATHOLOGIE 2000; 52:195-200. [PMID: 10930119 DOI: 10.1016/s0940-2993(00)80028-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
The role of growth factors in the development of murine uterine mesenchymal tumors is unknown. In this study, immunohistochemical expression of transforming growth factor alpha (TGF-alpha) and its receptor epidermal growth factor (EGF-R) was assessed in spontaneous uterine leiomyomas and leiomyosarcomas in B6C3F1 mice. Cell proliferation, which has been induced by some growth factors, was evaluated by immunohistochemical detection of an endogenous marker of cell proliferation, proliferating cell nuclear antigen (PCNA). PCNA labeling indices were determined and compared to the intensity and distribution of TGF-alpha staining in sequential sections of control myometrium or tumor tissue. Results showed uterine leiomyosarcomas had positive cytoplasmic staining for TGF-alpha; however, all uterine leiomyomas evaluated were negative. Positive EGF-R staining was also observed in the uterine leiomyosarcomas, but not in the leiomyomas. EGF-R immunoexpression was detected primarily within the cytoplasm of the leiomyosarcoma cells, with occasional nuclear immunoreactivity. Immunohistochemical staining for PCNA was more intense and there were increased numbers of positively staining nuclei in the leiomyosarcomas compared to samples of control myometrium or leiomyomas. The mean labeling index for the uterine leiomyosarcomas (7.40%) was significantly (p < 0.01) higher than that of leiomyomas (0.29%) and control uterine myometrium (0.13%). We conclude, that TGF-alpha and its receptor, EGF-R, are expressed more intensely in uterine leiomyosarcomas, compared to leiomyomas in B6C3F1 mice. Immunoexpression of TGF-alpha may be an important biomarker of malignancy in uterine smooth muscle tumors in mice. Futhermore, TGF-alpha may play a critical role in increased proliferation of uterine smooth muscle tumor cells as suggested by increased immunolocalization of PCNA in rodent leiomyosarcomas expressing TGF-alpha, although other factors regulating cell replication can not be ruled out.
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Yoshida A, Newbold RR, Dixon D. Abnormal cell differentiation and p21 expression of endometrial epithelial cells following developmental exposure to diethylstilbestrol (DES). Toxicol Pathol 2000; 28:237-45. [PMID: 10805141 DOI: 10.1177/019262330002800203] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Gene expression relevant to abnormal cell differentiation and altered cell cycle in endometrial epithelial cells was investigated immunohistochemically in developing mouse uteri exposed neonatally to diethylstilbestrol (DES). Female CD-1 mice were given daily s.c. injections of 2 microg of DES in corn oil or were given corn oil alone (control) at 1-5 days of age and euthanatized at 5, 6, 7, 8, 15, and 22 days of age. The endometrial epithelial cells of DES-treated mice at 5-8 days of age showed enhanced staining intensity for the estrogen receptor alpha (ER alpha), whereas the stromal cells showed decreased staining reaction; the epithelial cells showed that the protein encoded by the c-fos proto-oncogene, which plays a key role in regulating diverse estrogen-related cellular differentiation patterns, was enhanced. These cells also showed increased expression of lactoferrin, a sensitive protein marker of estrogen exposure, although the staining intensity decreased after exposure ended. The stain for p21 protein, a mitotic inhibitor which suppresses cyclin-dependent kinase activity, showed frequent positively stained cells in DES-treated mice at 5-15 days of age, whereas no accumulation of p53 protein of either wild or mutant type was detected immunohistochemically in these cells. These results indicate that suppressed cell cycle activity of endometrial epithelial cells and abnormal estrogen-related differentiation at the developmental stage following neonatal DES exposure may be caused, in part, by transient altered expression of ER alpha and expression of the p21 gene, which appears to be induced by a p53-independent mechanism.
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67
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Leark R, Dixon D, Hoffman T, Huynh D. An investigation into the effects of malingering on the test of variables of attention (TOVA) in a college aged sample. Arch Clin Neuropsychol 1999. [DOI: 10.1093/arclin/14.8.726b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Dixon D, Marks M. Making mergers, acquisitions & alliances work. What health care leaders need to know to avoid common pitfalls. HEALTH FORUM JOURNAL 1999; 42:30-3. [PMID: 10662150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
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Yoshida A, Newbold RR, Dixon D. Effects of neonatal diethylstilbestrol (DES) exposure on morphology and growth patterns of endometrial epithelial cells in CD-1 mice. Toxicol Pathol 1999; 27:325-33. [PMID: 10356709 DOI: 10.1177/019262339902700308] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The effects of neonatal diethylstilbestrol (DES) exposure on the morphology and proliferating patterns of endometrial epithelial cells were investigated at various stages of development in mice. Female CD-1 mice were given daily subcutaneous injections of 2 micrograms of DES in corn oil or corn oil alone (control) at 1-5 days of age and were killed at 5, 6, 7, 8, 15, and 22 days of age. At 5 days of age, the uteri of DES-treated mice had expanded lumina and undulated luminal surfaces lined by slightly elongated epithelial cells. At 6-8 days of age, marked infolding of clusters of hypertrophic elongated luminal epithelial cells was present; uteri had disorganized endometrial stromal and myometrial layers. At 15 and 22 days of age, the tissues from DES-treated mice had decreased numbers of endometrial glands, minimal stromal fibrosis, and smaller uterine horns than did the controls. Ultrastructurally, the endometrial epithelial cells of DES-treated mice at 5 and 8 days of age had distorted nuclei with condensed matrix and abundant secretory granules associated with rough endoplasmic reticulum and Golgi apparatus. At 8 days of age, an accumulation of fingerlike cytoplasmic processes that extended into the separated intercellular spaces and along the basal aspects of the endometrial epithelial cells were also observed. At 5-8 days of age, the proliferative activity of endometrial epithelial cells in DES-treated mice, identified by bromodeoxyuridine labeling, was significantly lower (10.5-1.7%) than that of the controls (25.5-19.8%). In situ analysis of endometrial luminal epithelial cells for DNA fragmentation representing apoptosis revealed < or = 0.1% and > 10% in the DES-treated and control mice at 5-8 days of age, respectively. The data show that cell cycle kinetics, in addition to changes in morphology, are altered in the developing mouse uterus following neonatal exposure to DES.
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Campbell L, Rehr JJ, Schenter GK, McCarthy MI, Dixon D. XAFS Debye-Waller factors in aqueous Cr+3 from molecular dynamics. JOURNAL OF SYNCHROTRON RADIATION 1999; 6:310-312. [PMID: 15263290 DOI: 10.1107/s0909049598018202] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1998] [Accepted: 12/21/1998] [Indexed: 05/24/2023]
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71
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Dixon D, Fordham-Skelton T. Plant-microbe interactions. CURRENT OPINION IN PLANT BIOLOGY 1998; 1:283-284. [PMID: 10066613 DOI: 10.1016/1369-5266(88)80046-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Dixon D, Fordham-Skelton T. Physiology and metabolism. CURRENT OPINION IN PLANT BIOLOGY 1998; 1:195. [PMID: 10066597 DOI: 10.1016/s1369-5266(98)80103-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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73
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Dixon D, Moyana T, King MJ. Elevated expression of the cdc25A protein phosphatase in colon cancer. Exp Cell Res 1998; 240:236-43. [PMID: 9596996 DOI: 10.1006/excr.1998.3940] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nuclear protein phosphatase cdc25A has been postulated to be a protooncogene. The total nuclear phosphotyrosyl protein phosphatase (PTP) activity and the expression of cdc25A were compared in normal and cancerous colon epithelial tissue. Nuclei derived from normal mucosal epithelium and tumors were analyzed for phosphotyrosyl protein phosphatase activity using the malachite green assay and a synthetic phosphotyrosyl peptide based on the sequence of cdc2, a known cdc25A phosphotyrosyl protein substrate. Tumorigenesis resulted in elevated nuclear PTP activity (343.0 +/- 37.0% of normal epithelial PTP activity) in 52% (29 of 56) of colon tumors. In all cases elevated nuclear PTP activity correlated with an increase in the expression of cdc25A. The changes in PTP activity observed were not due to any increase in the rate of growth of the colonic mucosa as no corresponding changes occurred with PTP activity under conditions of rapid mucosal growth.
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Trukhanova LS, Hong HH, Sills RC, Bowser AD, Gaul B, Boorman GA, Turusov VS, Devereux TR, Dixon D. Predominant p53 G-->A transition mutation and enhanced cell proliferation in uterine sarcomas of CBA mice treated with 1,2-dimethylhydrazine. Toxicol Pathol 1998; 26:367-74. [PMID: 9608642 DOI: 10.1177/019262339802600310] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mouse uterine tumors were examined for genetic alterations in the ras proto-oncogene and p53 tumor suppressor gene and for other biologically relevant immunohistochemical markers that may increase our understanding of the events that occur in uterine cancer. Fourteen dimethylhydrazine (DMH)-induced uterine sarcomas, including 3 primary malignant fibrous histiocytomas (MFH), 7 transplanted MFH, 3 stromal sarcomas, and 1 undifferentiated sarcoma, were first screened by immunohistochemistry for p53 missense mutations, followed by single strand conformation polymorphism analysis and DNA sequencing for the identification of point mutations. There was 100% correlation between p53 protein immunopositivity and subsequent detection of p53 mutations in DMH-induced malignant fibrous histiocytomas. All MFH had a characteristic p53 G:C-->A:T transition mutation, consistent with O6-methylguanine mispairing with thymine, the most common DNA lesion caused by alkylating agents. DMH-induced uterine MFH with p53 mutations also had a higher proliferative rate (qualitatively evaluated by immunohistochemical detection of proliferating cell nuclear antigen) when compared with other DMH-induced sarcomas. Uterine sarcomas were further evaluated for biological end points, such as estrogen receptor and desmin. Neoplastic cells from stromal sarcomas (SS), undifferentiated sarcomas (US), and MFH did not stain for desmin. The estrogen receptor was detected in normal uteri and a small portion of MFH, SS, and US. Our data suggest that DMH-induced uterine sarcomas are not consistent with smooth muscle cell origin and that a subset of these tumors, specifically DMH-induced malignant fibrous histiocytomas, have unique p53 G:C-->A:T transitions and a high proliferative rate.
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