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At least 667 records · Page 37Linked to original sources
PubMed2007

Activin a efficiently specifies definitive endoderm from human embryonic stem cells only when phosphatidylinositol 3-kinase signaling is suppressed.

Human ESCs (hESCs) respond to signals that determine their pluripotency, proliferation, survival, and differentiation status. In this report, we demonstrate that phosphatidylinositol 3-kinase (PI3K) antagonizes the ability of hESCs to differentiate in response to transforming growth factor beta family members such as Activin A and Nodal. Inhibition of PI3K signaling efficiently promotes differentiation of hESCs into mesendoderm and then definitive endoderm (DE) by allowing them to be specified by Activin/Nodal signals present in hESC cultures. Under conditions where hESCs are grown in mouse embryo fibroblast-conditioned medium under feeder-free conditions, approximately 70%-80% are converted into DE following 5 days of treatment with inhibitors of the PI3K pathway, such as LY 294002 and AKT1-II. Microarray and quantitative polymerase chain reaction-based gene expression profiling demonstrates that definitive endoderm formation under these conditions closely parallels that following specification with elevated Activin A and low fetal calf serum (FCS)/knockout serum replacement (KSR). Reduced insulin/insulin-like growth factor (IGF) signaling was found to be critical for cell fate commitment into DE. Levels of insulin/IGF present in FCS/KSR, normally used to promote self-renewal of hESCs, antagonized differentiation. In summary, we show that generation of hESC-DE requires two conditions: signaling by Activin/Nodal family members and release from inhibitory signals generated by PI3K through insulin/IGF. These findings have important implications for our understanding of hESC self-renewal and early cell fate decisions.

Activins↗
PubMed1996

Endodermal sinus tumor of the ovary: imaging evaluation.

OBJECTIVE: Endodermal sinus tumor of the ovary is a rare complex malignant tumor that occurs in young women. We performed this study to determine the imaging characteristics of this tumor. CONCLUSION: Endodermal sinus tumor of the ovary presents as a large complex abdominal mass that can be predominantly cystic and should be considered in the differential diagnosis of complex abdominal masses in girls and young women. In addition, upon encountering a mass with these imaging characteristics in the proper clinical setting, serum alpha-fetoprotein levels should be measured to help make a presurgical diagnosis and to obtain a baseline value.

Adolescent↗
PubMed1997

Primary endodermal sinus tumor presenting with spinal cord compression. Case report.

Endodermal sinus tumor is an uncommon malignant germ-cell neoplasm. These tumors usually present in childhood or young adulthood as testicular or ovarian masses; however, mediastinal and intracranial tumors have been described. The authors report the occurrence of a primary paraspinal endodermal sinus tumor in a 21-month-old boy who presented with thoracic spinal cord compression. A review of the literature failed to reveal a similar case. The clinical presentation, radiographic characteristics, operative findings, and patient outcome are discussed.

Endodermal Sinus Tumor↗
PubMed1994

Endodermal sinus tumor: immunophenotypic expression of a carcinoma.

A series of five endodermal sinus tumors was studied for their cytoskeletal and other phenotypic markers. They included 2 ovarian, 2 testicular, and 1 inguinal tumors. The cytoskeletal expression was also studied by gel electrophoresis and immunoblotting. Every tumor was diffusely and strongly immunostained for cytokeratin. By SDS-PAGE and immunoblotting, cytokeratins 8 & 18 were detected. Vimentin was focally coexpressed in 4 cases. The stroma was diffusely immunostained for vimentin. None of them expressed desmin, neurofilament, or glial filament protein. Desmoplakin was expressed only in one ovarian tumor. Alpha-fetoprotein and S-100 protein were also diffusely positive among the neoplastic cells; intracytoplasmic globules were especially strongly immunostained. These findings suggest that endodermal sinus tumors represent a group of pure malignant epithelial neoplasms, and may be regarded as primitive carcinomas.

Adult↗
PubMed2001

Adenovirus-mediated increase of HNF-3 levels stimulates expression of transthyretin and sonic hedgehog, which is associated with F9 cell differentiation toward the visceral endoderm lineage.

Retinoic acid-induced differentiation of mouse F9 embryonal carcinoma cells toward the visceral endoderm lineage is accompanied by increased expression of the Forkhead Box (Fox) transcription factors hepatocyte nuclear factor 3a (HNF-3alpha) and HNF-3beta, suggesting that they play a crucial role in visceral endoderm development. Retinoic acid stimulation results in a cascade of HNF-3 induction in which HNF-3alpha is a primary target for retinoic acid action and its increase is required for subsequent induction of HNF-3beta expression. Increased expression of HNF-3beta precedes activation of its known target genes, including transthyretin (TTR), Sonic hedgehog (Shh), HNF-1alpha, HNF-1beta, and HNF-4alpha. In order to examine whether increased HNF-3 expression is sufficient to induce expression of its downstream target genes without retinoic acid stimulation, we have used adenovirus-based expression vectors to increase HNF-3 protein levels in F9 cells. We demonstrate that adenovirus-mediated increase of HNF-3alpha levels in F9 cells is sufficient to induce activation of endogenous HNF-3beta levels followed by increased TTR and Shh expression. Furthermore, we show that elevated HNF-3beta levels stimulate expression of endogenous TTR and Shh without retinoic acid stimulation. Moreover, ectopic HNF-3 levels in undifferentiated F9 cells are insufficient to induce HNF-3alpha, HNF-1alpha, HNF-1beta, and HNF-4alpha expression, suggesting that their transcriptional activation required other regulatory proteins induced by the retinoic acid differentiation program. Finally, our studies demonstrate the utility of cell infections with adenovirus expressing distinct transcription factors to identify endogenous target genes, which are assembled with the appropriate nucleosome structure.

Adenoviridae↗
PubMed1999

Signals governing extraembryonic endoderm formation in the mouse: involvement of the type 1 parathyroid hormone-related peptide (PTHrP) receptor, p21Ras and cell adhesion molecules.

The formation of parietal endoderm (PE) from primitive endoderm (PrE) immediately after implantation of the early mouse embryo can be seen as the earliest example of an epithelio-mesenchyme transition (EMT) in murine development. Since EMT and EMI (epithelium-mesenchyme interactions) are at the very heart of morphogenesis, identifying molecular mechanisms governing these processes is of utmost importance. An excellent in vitro model system to study PE formation, i.e. F9 embryonal carcinoma cells, is available to this end. In the present paper we review our own recent results and those of others using these cells, and present our current view on the molecular mechanisms involved in PE formation.

Animals↗
PubMed2000

Mediastinal endodermal sinus tumour: surgical role in chemotherapy resistant cases.

We report two cases of aggressive mediastinal endodermal sinus tumours (EST) detected incidentally on a chest radiograph. The patients were being investigated for minor chest complaints. After three courses of cisplatin-based chemotherapy the tumour marker levels declined. However, the tumour size continued to increase. Complete surgical removal was possible in one case and significant reduction in tumour mass was achieved in the other. Reduction in the viable, tumour tissue load made the residual tumour sensitive to postoperative chemotherapy. It is important to be aware of endodermal sinus tumours refractory to chemotherapy which may require early surgical intervention.

Adult↗
PubMed2005

Gene transfer into mouse prepancreatic endoderm by whole embryo electroporation.

CONTEXT: Understanding gene function in the developing pancreas is a major issue for pancreatic cell therapy. The in vivo analysis of gene function has essentially been performed by modulating gene expression in transgenesis. A faster and easier method is electroporation of mouse embryos. This technique, coupled with whole embryo culture, enables one to deliver genes and analyze their effects in a spatially and temporally regulated manner. OBJECTIVE: We wanted to adapt the electroporation technique for gene transfer of whole e8.5 mouse embryos into the endoderm to allow expression of transgenes in the pancreas or liver. RESULTS: Using two platinum plate electrodes, low voltage and a precise positioning of the embryo in the electroporation cuvette we could target and express DNA constructs in the prepancreatic or prehepatic territories, identified with cell markers. We also demonstrated that this technique is a valuable tool in the study of transcriptional regulation in the developing endoderm. CONCLUSIONS: Targeted electroporation of whole embryos is a useful method of characterizing the gene network which controls pancreatic development.

Animals↗
PubMed2006

Primary yolk sac tumor (endodermal sinus tumor) of the vulva: case report and review of the literature.

INTRODUCTION: Endodermal sinus tumor (EST) or primary yolk sac tumor (YST) of the vulva is extremely rare and a highly malignant germ cell tumor. Only nine cases of vulvar YST have been reported to the world literature to date. We present the tenth case of endodermal sinus tumor of the vulva. CASE: A 32-year-old white virgin presented with a 3.5 cm right labial mass without any other signs or symptoms. Excisional biopsy showed YST with a predominantly solid pattern. Unilateral hemivulvectomy with bilateral inguinal lymphadenectomy was performed. Six months after surgery there was a recurrence. She was treated with three courses of the BEP regimen (bleomycin, etoposide, cisplatin). The patient refused to take any further treatment including radiotherapy. The serum alpha-fetoprotein (AFP) was not elevated at the initial diagnosis however it was elevated during recurrence. The patient is alive with the disease 42 months after the first appearance of the vulvar mass.

Adult↗
PubMedDate not supplied

[Immunological localization of alpha-fetoprotein in the proximal endoderm and its significance in extra-embryonic differentiation of teratocarcinomas in the mouse].

The ABC technique using a specific anti-mouse alpha-foetoprotein (AFP) serum permits identification of groups of extraembryonic proximal endoderm cells in certain teratocarcinomas. These AFP+ cells are always associated with trophoblastic and parietal endodermal patterns and structures. These observations strongly support the hypothesis of a common precursor to the extraembryonic tissues which appears during the first phases of egg development.

Animals↗
PubMed1985

Congenital polycystic tumor of the atrioventricular node. Autopsy study with immunohistochemical findings suggesting endodermal derivation.

Atrioventricular node congenital polycystic tumor, a lesion that causes heart block and sudden unexpected death, has been postulated to arise from the lymphatics, foregut endoderm, cardiac mesoderm, and mesothelium since its initial description in 1911. No theory concerning the histogenesis of this tumor has been completely satisfactory, either from an embryologic or a clinical standpoint. Biologic studies including cell culture systems from the lesions as well as optimal ultrastructural examination have been compromised due to postmortem autolysis. We studied four examples of this entity by standard histochemical stains for mucopolysaccharides, and by modified immunohistochemical labeling for carcinoembryonic antigen, factor VIII, and keratin. Results suggest an origin from foregut endoderm. The lesion has not been reported to be outside the region of the atrioventricular junction, but was demonstrated in the thymus gland in one of our cases.

Adult↗
PubMed1989

An extensive increase of junctional communication capacity in endoderm development of the Xenopus embryo.

The present result shows that in blastula and gastrula stages although endoderm cells of the Xenopus embryo may be electrically coupled with each other, most of them can not detectably transfer the 376 dalton molecular weight tracer, the carboxyfluorescein, to their contiguous neighbor cells. They become capable of such junctional dye transfer at the end of gastrulation. This transition reflects temporally well ordered development of junctional communication capacity from low to high level, which may be related to the developmental program of endodermal cellular differentiation. The time course of this transition provides a measure for study of the effects of various factors on the development of junctional communication capacity in this embryo.

Animals↗
PubMed1988

The synthesis of peptides in enteroendocrine cells developing in explanted presumptive endoderm.

Peptide immunoreactivity was studied in grafts of endoderm from chick or quail embryos (19 hours, corresponding to stage 4- to 5 according to Hamburger and Hamilton) in the coelom of a 48 hour host embryo. The presence of gastrin, glucagon, cholecystokinin, VIP, substance P, somatostatin, bombesin, motilin, secretin, pancreatic polypeptide, neurotensin and insulin was demonstrated. The nature of the peptide(s) generally matched the regional differentiation of the enteric epithelium and the underlying mesodermal components. The findings are compatible with the concept of heterogeneity of the endoderm due to migration of epiblast derived cells.

Animals↗
PubMed1986

Regional and temporal differences in the parietal endoderm of the midgestation mouse embryo.

The morphological appearance of parietal endoderm (PE) cells from ninth to fourteenth day mouse embryos was examined by light and scanning electron microscopy, and their behaviour in vitro was studied using time-lapse video recordings. At all ages, the PE cells proximal to the placenta had a predominantly blebby phenotype whilst, in all but the youngest embryos studied, the distal cells were smooth and rounded. In the older embryos, the cells in the middle and distal regions had numerous short filopodia and were sometimes very large and flattened. Time-lapse studies on tenth day preparations showed intense motile activity (though little net movement) of the PE cells in the proximal region, with relatively little activity in more distal regions. The cell activity was generally less in eleventh day preparations, though it was still significantly greater in the proximal zone than elsewhere. The significance of these observations for understanding the development of the parietal endoderm is discussed.

Animals↗
PubMed1995

[Response of ovarian endodermal sinus tumor to combination chemotherapy with cis-platinum, vincristine and bleomycin or vincristine, actinomycin and cyclophosphamide].

The treatment results of 63 cases of ovarian endodermal sinus tumor admitted to Peking Union Medical College Hospital from August 1977 through April 1992 by combination chemotherapy were reported. Patients were divided into three groups. The first group received full courses of vincristine, actinomycin and cyclophosphamide (VAC) or cis-platinum, vincristine and bleomycin (PVB) chemotherapy in adequate dosages (37 cases). The second group also received VAC or PVB chemotherapy but in inadequate dosages (17 cases). The third group took no VAC or PVB chemotherapy but some other chemotherapeutic drugs (9 cases). 28 of the 63 patients died. The 35 surviving patients have been followed for 1 to 15 years. The sustained remission rates were 81.1%, 23.5% and 11.1% for the first, second and third group respectively. As the ovarian endodermal sinus tumor is very sensitive to VAC or PVB chemotherapy an extensive or aggressive cytoreductive surgery and retroperitoneal lymphadenectomy seemed to be not necessary. Such a point of view is demonstrated by our preliminary study. The treatment results for the primary cases are significantly better than that of the recurrent cases. The sustained remission rate is 94.7% for the former while that for the latter is 66.7%.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

An amphioxus Pax gene, AmphiPax-1, expressed in embryonic endoderm, but not in mesoderm: implications for the evolution of class I paired box genes.

Class I paired box genes are widely distributed through the animal phyla but only fruitfly Pox meso and vertebrate Pax-1 and Pax-9 have been adequately characterized. These vertebrate genes have several developmental functions, but their role in patterning the axial skeleton has received the most attention. Because axial skeletons appear after the origin of the vertebrates, special interest attaches to the possible functions of the precursors of Pax-1 and Pax-9 in the invertebrate ancestor of the vertebrates. As a proxy for this ancestor, we studied amphioxus, which is widely thought to be the closest living invertebrate relative of the vertebrates. A cDNA library from developing amphioxus yielded an unequivocal class I paired box gene, AmphiPax-1, that is 2.5 kb long. The gene encodes a 337 amino acid protein that includes a paired domain in which the amino acids are 92% identical to the paired domain amino acids of mouse and human Pax-1 and Pax-9. In situ hybridization detects AmphiPax-1 expression only in the endoderm of the developing pharynx; within this tissue, expression becomes strikingly down-regulated in regions that will fuse with the overlying ectoderm to form gill slits. No transcripts of AmphiPax-1 ever become detectable in any mesodermal structures. We think it likely that, during animal evolution, class I paired box genes originally functioned in endoderm development and were only later co-opted for other roles in mesoderm development; however, other scenarios cannot be ruled out until homologues of these genes are studied in more invertebrate phyla and in the lower vertebrates.

Amino Acid Sequence↗