Lactose and benign ovarian tumours in a case-control study.
(41/1513)
We investigated the relation between benign ovarian tumours and lactose among 746 case women identified at seven New York metropolitan hospitals and 404 community controls, age and hospital frequency matched to the expected case distribution. No increase in risk was found for lactose (highest quartile versus lowest: adjusted odds ratio = 0.82 (95% CI 0.57-1.20) or for any other lactose foods. (+info)
IGF-II promotes mesoderm formation.
(42/1513)
IGF-II is abundant in the nascent mesoderm of the gastrulating mouse embryo. Its function at this developmental stage is unknown. We investigated it by following the in vitro and in vivo differentiation of several androgenetic, biparental, parthenogenetic, and androgenetic Igf2 -/- murine ES cell lines; these cells differed in endogenous IGF-II levels because Igf2 is paternally expressed in the mouse embryo in most tissues. The expression of mesoderm markers and the subsequent formation of muscle structures were correlated with endogenous IGF-II level during teratoma formation and during in vitro differentiation. In addition, the absence of Igf2 in androgenetic Igf2 -/- ES cells led to a severe impairment of mesoderm development, demonstrating the dependence of the preferential mesoderm development of androgenetic ES cells upon Igf2 activity, among the numerous known imprinted genes. The addition of exogenous IGF-II to in vitro differentiation culture medium led to a specific increase in the expression of mesoderm markers. Thus, we propose a novel model in which the binding of IGF-II to its principal signaling receptor, IGF1R, at the surface of mesoderm precursor cells increases the formation of mesoderm cells. (+info)
The management of mature cystic teratomas in children and adolescents: a retrospective analysis.
(43/1513)
Mature cystic teratomas (MCT) are the most common ovarian tumours seen in children and adolescents. Fifty-two patients <21 years of age had surgical removal of an MCT, 14 of whom were approached laparoscopically. Compared with laparotomy, those patients managed laparoscopically had a significantly shorter hospital stay. Intra-operative tumour spillage occurred in 27 (52%) patients; there were no cases of chemical peritonitis. Available follow-up data on 34 (65%) patients revealed seven pregnancies occurring at a median of 70 months (46-123) postoperatively, including four in patients with intraoperative MCT spill. There were no cases of tumour recurrence during the follow-up period among the 27 (52%) patients managed with ovarian cystectomy. These results demonstrate that some of the conclusions regarding the contemporary management of MCT in adults are applicable to children and adolescents. (+info)
Requirement of the RNA editing deaminase ADAR1 gene for embryonic erythropoiesis.
(44/1513)
The members of the ADAR (adenosine deaminase acting on RNA) gene family are involved in site-selective RNA editing that changes adenosine residues of target substrate RNAs to inosine. Analysis of staged chimeric mouse embryos with a high contribution from embryonic stem cells with a functional null allele for ADAR1 revealed a heterozygous embryonic-lethal phenotype. Most ADAR1+/- chimeric embryos died before embryonic day 14 with defects in the hematopoietic system. Our results suggest the importance of regulated levels of ADAR1 expression, which is critical for embryonic erythropoiesis in the liver. (+info)
Alleviation of murine leukemia virus repression in embryonic carcinoma cells by genetically engineered primer binding sites and artificial tRNA primers.
(45/1513)
The primer binding site (PBS) plays pivotal roles during reverse transcription of retroviruses and also is the target of a cellular host defense impeding the transcription of murine leukemia virus (MLV) harboring a proline (pro) PBS in embryonic cells. Both the PBS and the tRNA primer are copied during reverse transcription and anneal as complementary DNA sequences creating the PBS of the integrated provirus. The pro PBS of MLV can be exchanged by PBS sequences matching endogenous or engineered tRNAs to allow replication of Akv MLV-derived vectors in fibroblasts. Here we use the PBS escape mutant B2 to demonstrate the capacity of the synthetic tRNA(B2) to function in reverse transcription in competition with endogenous tRNAs in fibroblasts and embryonic carcinoma (EC) cells. We further show symmetry between PBS and the primer by the ability of the synthetic tRNA(B2) to confer escape from EC repression of a PBS-Pro vector. Of a panel of vectors with the repressed pro PBS substituted for other natural or artificial PBS sequences, all except one efficiently expressed the neo marker gene when transferred to NIH/3T3 and EC cells, hence avoiding PBS-mediated silencing in EC cells. A non-natural PBS matching an artificially designed tRNA molecule conferred no further relief from repression than that attained with the B2 escape mutant or the natural alternative PBSs. Interestingly, a vector harboring a PBS matching tRNA(Lys1.2) suffered repression similar to the wild-type PBS-Pro but was partially rescued by a single point mutation of the PBS. (+info)
Combination of a teratoma and embryonal carcinoma of the testis in SD IGS rats: a report of two cases.
(46/1513)
Testicular tumors of germ cell origin are extremely rare in rats. We encountered 2 cases of teratoma and embryonal carcinoma in the testes of 8- and 10-week-old Sprague-Dawley IGS rats. A unilateral tumor mass with bilateral testicular atrophy was observed macroscopically in both cases. Microscopic examination revealed that the tumor mass had characteristic features of a teratoma and was composed of several types of differentiated cells and tissues at various stages of maturation. Embryonal carcinoma tissue, composed of undifferentiated cells with an embryonic and anaplastic appearance, was observed within the tumor mass. In addition, foci of intratubular teratomas and embryonal carcinomas were observed in the testis on the side without any obvious mass. No obvious germ cells were observed in the seminiferous tubules in the remnant nontumorous area. Furthermore, intratubular transition of cells was observed from the embryonal carcinoma tissue to the squamous epithelium. This finding indicates that an embryonal carcinoma differentiates toward a teratoma even at a very early stage of development of the germ cell tumor. (+info)
Determination of hypoxic region by hypoxia marker in developing mouse embryos in vivo: a possible signal for vessel development.
(47/1513)
Hypoxia is a well-known signal for angiogenesis, but the recent proposal that hypoxia exists in developing embryonic tissues and that it induces vascular development remains to be proven. In the present study, we demonstrate the presence of hypoxia in normal developing embryos by means of a hypoxia marker, pimonidazole, and its associated antibody. Our data clearly show that hypoxia marker immunoreactivity was highly detected in developing neural tubes, heart, and intersomitic mesenchyme at an early stage of organogenesis, suggesting that hypoxia may exist in the early stages of embryo development. We also found that hypoxia inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) were spatiotemporally co-localized with possible hypoxic regions in embryos. Investigation of platelet endothelial cell adhesion molecule (PECAM) expression provides evidence that endothelial cells proliferate and form the vessels in the hypoxic region in developing organs. Furthermore, we found that hypoxia induced both HIF-1alpha and VEGF in F9 embryonic stem and differentiated cells. Thus, we suggest that hypoxia may exist widely in developing embryonic tissues and that it may act as a signal for embryonic blood vessel formation in vivo. (+info)
Intrapericardial teratoma--a report of two cases.
(48/1513)
Two rare cases of intra-pericardial teratoma in infants are reported. The presenting symptoms were either due to pericardial effusion and cardiac tamponade or due to compression of the tracheo-bronchial tree. The tumors were well encapsulated and were attached to the ascending aorta. Histologically, they were composed of derivatives of the three germ cell layers. (+info)