Biomedical subjects

Ruth Birbe

Publications and source records attributed to Ruth Birbe.

8 recordsLinked to original sources

PubMed2006

A validated quantitative assay to detect occult micrometastases by reverse transcriptase-polymerase chain reaction of guanylyl cyclase C in patients with colorectal cancer.

PURPOSE: Guanylyl cyclase C (GCC), a receptor for bacterial diarrheagenic enterotoxins, may be a prognostic and predictive marker to detect occult micrometastases in patients undergoing staging for colorectal cancer. However, quantification of GCC expression in tissues by the quantitative reverse transcription-PCR (qRT-PCR) has not undergone analytic and clinicopathologic validation. EXPERIMENTAL DESIGN: A technique to quantify GCC mRNA in tissues employing RT-PCR was developed and validated employing external calibration standards of RNA complementary to GCC. RESULTS: GCC qRT-PCR exhibited reaction efficiencies >92%, coefficients of variations <5%, linearity >6 orders of magnitude, and a limit of quantification of >25 copies of GCC cRNA. This assay confirmed that GCC mRNA was overexpressed by colorectal tumors from 41 patients, which correlated with increased GCC protein quantified by immunohistochemistry. Analyses obtained with 164 lymph nodes from patients free of cancer and 15 nodes harboring metastases established a threshold for metastatic disease of approximately 200 GCC mRNA copies/mug total RNA, with a sensitivity of 93% and specificity of 97%. GCC mRNA above that threshold was detected in 76 of 367 (approximately 21%) nodes free of disease by histopathology from 6 of 23 (26%) patients, suggesting the presence of occult micrometastases. CONCLUSIONS: Quantifying GCC mRNA in tissues by RT-PCR employing external calibration standards is analytically robust and reproducible, with high clinicopathologic sensitivity and specificity. This validated assay is being applied to approximately 10,000 lymph nodes in a prospective trial to define the sensitivity of GCC qRT-PCR for staging patients with colorectal cancer.

Adult↗

PubMed2006

Bile acids induce ectopic expression of intestinal guanylyl cyclase C Through nuclear factor-kappaB and Cdx2 in human esophageal cells.

BACKGROUND & AIMS: Although progression to adenocarcinoma at the gastroesophageal junction reflects exposure to acid and bile acids associated with reflux, mechanisms mediating this transformation remain undefined. Guanylyl cyclase C (GC-C), an intestine-specific tumor suppressor, may represent a mechanism-based marker and target of transformation at the gastroesophageal junction. The present studies examine the expression of GC-C in normal tissues and tumors from esophagus and stomach and mechanisms regulating its expression by acid and bile acids. METHODS: Gene expression was examined by reverse-transcription polymerase chain reaction, promoter analysis, immunohistochemistry, immunoblotting, and functional analysis. Promoter transactivation was quantified by using luciferase constructs and mutational analysis. DNA binding of transcription factors was examined by electromobility shift analysis. RESULTS: GC-C mRNA and protein were ectopically expressed in approximately 80% of adenocarcinomas arising in, but not in normal, esophagus and stomach. Similarly, in OE19 human esophageal cancer cells, deoxycholate and acid induced expression of GC-C. This was associated with the induction of expression of Cdx2, a transcription factor required for GC-C expression. In turn, induction of Cdx2 expression by deoxycholate was mediated by binding sites in the proximal promoter for nuclear factor kappaB (NF-kappaB). Furthermore, deoxycholate increased NF-kappaB activity, associated with nuclear translocation and Cdx2 promoter binding of the NF-kappaB subunit p50. Moreover, a dominant negative construct for NF-kappaB prevented deoxycholate-induced p50 nuclear translocation and activation of the Cdx2 promoter. CONCLUSIONS: Transformation associated with reflux at the gastroesophageal junction reflects activation by bile acid and acid of a transcriptional program involving NF-kappaB and Cdx2, which mediate intestinal metaplasia and ectopic expression of GC-C.

Adenocarcinoma↗

PubMed2005

Analysis of KIT mutations in sporadic and familial gastrointestinal stromal tumors: therapeutic implications through protein modeling.

PURPOSE: Gastrointestinal stromal tumors (GIST) are characterized by expressing a gain-of-function mutation in KIT, and to a lesser extent, PDGFR. Imatinib mesylate, a tyrosine kinase inhibitor, has activity against GISTs that contain oncogenic mutations of KIT. In this study, KIT and PDGFRalpha mutation status was analyzed and protein modeling approaches were used to assess the potential effect of KIT mutations in response to imatinib therapy. EXPERIMENTAL DESIGN: Genomic DNA was isolated from GIST tumors. Exons 9, 11, 13, and 17 of c-KIT and exons 12, 14, and 18 of PDGFRalpha were evaluated for oncogenic mutations. Protein modeling was used to assess mutations within the juxtamembrane region and the kinase domain of KIT. RESULTS: Mutations in KIT exons 9, 11, and 13 were identified in GISTs with the majority of changes involving the juxtamembrane region of KIT. Molecular modeling indicates that mutations in this region result in disruption of the KIT autoinhibited conformation, and lead to gain-of-function activation of the kinase. Furthermore, a novel germ-line mutation in KIT was identified that is associated with an autosomal dominant predisposition to the development of GIST. CONCLUSIONS: We have used protein modeling and structural analyses to elucidate why patients with GIST tumors containing exon 11 mutations are the most responsive to imatinib mesylate treatment. Importantly, mutations detected in this exon and others displayed constitutive activation of KIT. Furthermore, we have found tumors that are both KIT and PDGFRalpha mutation negative, suggesting that additional, yet unidentified, abnormalities may contribute to GIST tumorigenesis.

Adult↗

PubMed2005

Guanylyl cyclase C is a marker of intestinal metaplasia, dysplasia, and adenocarcinoma of the gastrointestinal tract.

Gastrointestinal (GI) tumors continue to be major causes of cancer-related mortality, in part, reflecting metastases that escape detection by histopathology. Moreover, although approximately 10% of carcinomas arise from unknown locations, these tumors frequently originate in the GI tract. Guanylyl cyclase C (GC-C) is a receptor selectively expressed by intestinal epithelial cells whose persistent expression by colorectal carcinomas and ectopic expression by adenocarcinomas of the upper GI tract suggest its use as a marker for GI malignancies. Here, expression of GC-C protein, identified by immunohistochemistry, was examined in tissues and tumors arising from the human GI tract. Guanylyl cyclase C protein was expressed by epithelial cells from the duodenum to the rectum, but not by those in normal esophagus and stomach. Expression was retained in tubular adenomas, inflammatory bowel disease, premalignant lesions, and in primary and metastatic adenocarcinomas from the colon, including metastases to lymph nodes and liver. Moreover, GC-C was ectopically expressed in all cases of dysplasia and adenocarcinomas arising from intestinal metaplasia in esophagus and stomach. Thus, GC-C appears to be an immunohistochemical marker for identifying adenocarcinomas of unknown origin, metastases in patients undergoing staging for GI adenocarcinomas, and intestinal metaplasia, dysplasia, and tumors arising therein in the upper GI tract.

Adenocarcinoma↗

PubMed2004

Gliosarcoma arising from an anaplastic ependymoma: a case report of a rare entity.

We report the first case of a gliosarcoma arising from an anaplastic ependymoma and the second case of gliosarcoma arising from any type of ependymal neoplasm. The patient was a 48-year-old woman with a solid and cystic, peripherally enhancing, 7-cm right frontal mass lesion. Histologically, the lesion displayed characteristics of anaplastic ependymoma (grade III, World Health Organization scale). The tumor recurred despite multiple cycles of postoperative radiation and chemotherapy. After the fourth recurrence, the tumor displayed a biphasic pattern of differentiation. The first pattern was similar to the original anaplastic ependymoma, whereas there was a second new sarcomatous pattern resembling fibrosarcoma that was admixed with and overrunning the ependymal component. The spectrum of gliosarcoma is therefore expanded to include not only astrocytic and oligodendroglial components but ependymal components as well.

Brain Neoplasms↗

PubMed2004

Hepatocyte growth factor treatment ameliorates diarrhea and bowel inflammation in a rat model of inflammatory bowel disease.

BACKGROUND/PURPOSE: Transfection of the HLA-B27 gene into normal Fischer rats induces phenotypic changes similar to inflammatory bowel disease (IBD). This study investigated the benefits of 2 doses of hepatocyte growth factor (HGF) on the manifestations of IBD in this rat model. METHODS: Fischer rats and HLA-B27 rats were divided into 4 groups: Fischer rats treated with saline, HLA-B27 rats treated with saline, HGF at 150 microg/kg/d, and HGF at 300 microg/kg/d. HGF or saline was infused for 14 days via an osmotic pump attached to a catheter in the internal jugular vein. After treatment, rats were evaluated for diarrhea and reduction in gross and microscopic bowel inflammation. Statistics were determined using analysis of variance (ANOVA). A P value < or =.05 was considered significant. RESULTS: Administration of HGF at 150 microg/kg/d decreased diarrhea by 40%, gross inflammation by 41%, and microscopic inflammation by 72% (P < or =.05). At 300 microg/kg/d HGF decreased diarrhea by 46%, gross inflammation by 45%, and microscopic inflammation by 54% (P < or =.05). CONCLUSIONS: HGF administration reduces the clinical manifestations of IBD in this rat model. Similar effects were seen at both doses of HGF administration, implying that there is a plateau above which further increases in HGF levels provides no added benefit. HGF administration may be clinically useful in the management of IBD.

Animals↗

PubMed2004

Glucagonlike peptide-2 analogue: a possible new approach in the management of inflammatory bowel disease.

BACKGROUND/PURPOSE: Glucagonlike peptide-2alpha (GLP-2alpha) has been shown to be a growth factor for the small intestine. This study investigated the benefits of intravenous and intraluminal administration of GLP-2alpha using a rat model of inflammatory bowel disease (IBD). METHODS: Normal Fisher rats and HLA-B27 (IBD) rats were treated for 14 days as follows: Fisher, intravenous saline (n = 6); HLA-B27, intravenous saline (n = 6); HLA-B27, intravenous GLP-2alpha (50 microg/kg/d; n = 5); Fisher, intraluminal saline (n = 5); HLA-B27, intraluminal saline (n = 5); or intraluminal GLP-2alpha (50 microg/kg/d; n = 5). Rats were evaluated for frequency of diarrhea, and the bowel was analyzed for gross and microscopic lesions. Statistical evaluations were determined using analysis of variance (ANOVA). A P value of.05 was significant. RESULTS: Intravenous GLP-2alpha decreased diarrhea and the number of bowel lesions (P <.05). Microscopic inflammation was reduced by 24% but was not statistically significant. Intraluminal GLP-2alpha decreased the number of small intestine lesions (P <.05) and the microscopic inflammation (P <.05) but did not significantly reduce diarrhea or the overall number of bowel lesions. CONCLUSIONS: GLP-2alpha ameliorates the signs of IBD in HLA-B27 rats. Intravenous GLP-2alpha reduces diarrhea more effectively than intraluminal administration, and both routes are equally effective in ameliorating inflammation. GLP-2alpha potentially provides a new modality for the treatment of IBD.

Analysis of Variance↗

PubMed2003

Multifocal epithelioid angiosarcoma of bone: a potential pitfall in the differential diagnosis with metastatic carcinoma.

A case of multifocal epithelioid angiosarcoma of the femur, tibia, fibula, and astragalus in a 54-year-old man is reported. The tumor was composed of nests and cords of malignant cells with epithelioid morphology, with foci of vascular differentiation, necrosis, and hemorrhage. By immunohistochemistry, the neoplastic cells showed positivity for endothelial cell markers (CD31, CD34, factor VIII-related antigen, and Ulex europaeus agglutinin I), epithelial markers (cytokeratins and epithelial membrane antigen), and vimentin. The authors' findings point out the need for a panel of antibodies for the careful search of histologic features of vascular differentiation to correctly diagnose vascular bone tumors with epithelioid features, especially in evaluating small core biopsy specimens in which a sheetlike rather than obviously vasoformative architecture may lead to an erroneous diagnosis of metastatic carcinoma.

Biomarkers↗