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Biomedical subjects

Michael Reiss

Publications and source records attributed to Michael Reiss.

50 records · Page 3Linked to original sources
PubMed2002

Unsupervised imaging, registration and archiving of tissue microarrays.

Tissue microarray (TMA) technology offers several advantages over traditional methods of specimen preparation by maximizing limited tissue resources and providing the means for visualizing molecular targets. Currently, the primary methods used to evaluate arrays involves the interactive review of TMA samples while they are viewed by microscope and are subjectively evaluated and scored. The process is slow, tedious and prone to error. In order to facilitate large-scale, multi-institutional studies a more automated and reliable means for processing tissue microarrays is needed. We have developed a web-based prototype which features automated imaging, registration and intelligent archiving of tissue microarrays in multi-user, network environments.

Databases, Factual↗
PubMed2001

Betaglycan inhibits TGF-beta signaling by preventing type I-type II receptor complex formation. Glycosaminoglycan modifications alter betaglycan function.

Transforming growth factor (TGF)-beta is a multifunctional growth factor with important roles in development, cell proliferation, and matrix deposition. It signals through the sequential activation of two serine/threonine kinase receptors, the type I and type II receptors. A third cell surface receptor, betaglycan, serves as a co-receptor for TGF-beta in some cell types, enhancing TGF-beta-mediated signaling. We have examined the function of betaglycan in renal epithelial LLC-PK1 cells that lack endogenous betaglycan. We demonstrate that the expression of betaglycan in LLC-PK1 cells results in inhibition of TGF-beta signaling as measured by reporter gene expression, thymidine incorporation, collagen production, and phosphorylation of the downstream signaling effectors Smad2 and Smad3. In comparison, the expression of betaglycan in L6 myoblasts enhances TGF-beta signaling, which is consistent with the published literature. The effects of betaglycan in LLC-PK1 cells are not mediated by ligand sequestration or increased production of a soluble form of the receptor, which has been reported to serve as a ligand antagonist. We demonstrate instead that in LLC-PK1 cells, unlike L6 cells, expression of betaglycan prevents association between the type I and type II TGF-beta receptors, which is required for signaling. This is a function of the glycosaminoglycan modifications of betaglycan. Betaglycan in LLC-PK1 cells exhibits higher molecular weight glycosaminoglycan (GAG) chains than in L6 cells, and a GAG- betaglycan mutant does not inhibit TGF-beta signaling or type I/type II receptor association in LLC-PK1 cells. Our data indicate that betaglycan can function as a potent inhibitor of TGF-beta signaling by a novel mechanism and provide support for an essential but complex role for proteoglycan co-receptors in growth factor signaling.

Activin Receptors, Type I↗
PubMedDate not supplied

Sequential high-dose alkylating therapy and stem cell support for high-risk stage III breast cancer.

Patients who receive neoadjuvant chemotherapy for locally advanced breast cancer and have four or more ipsilateral axillary lymph nodes involved at surgery are at high risk for recurrence, with a median time to relapse of 18 months. We offered such patients high-dose chemotherapy with stem cell rescue. Patients received cyclophosphamide or paclitaxel and granulocyte colony-stimulating factor (G-CSF) to mobilize stem cells. Melphalan 140 mg/m2 was then given with stem cell rescue. Twenty-four to 35 days later, thiotepa 900 mg/m2 was given with stem cell rescue. Patients with hormone receptor-positive tumors received tamoxifen. We treated 14 patients in this fashion from 1995 to 1998. The mean age was 46.7 years. The majority of cancers were stage IIIB (79%). Thirteen women underwent mastectomy after anthracycline-containing chemotherapy and 50% had more than seven positive lymph nodes. Hospitalization was principally for neutropenic fever. Other morbidities were pneumonitis, cardiomyopathy, and grade 3/4 white blood cell (WBC) toxicity. No patient died of a treatment-related complication. Seven of 14 relapsed at 10, 12, <15, 15, 17, 21, and 36 months, with median follow-up of 26.5 months. Time to relapse in this small series is only modestly improved over historical experience with standard-dose adjuvant chemotherapy. Alternative strategies for treating locally advanced breast cancer should be pursued.

Adult↗
PubMedDate not supplied

Loss of Smad signaling in human colorectal cancer is associated with advanced disease and poor prognosis.

PURPOSE: Based largely on in vitro investigations and animal studies, investigators believe that disruptions of transforming growth factor-beta (TGF-beta) signaling contribute to the development and progression of human colorectal cancer. The purpose of this study was to directly assess the status of the TGF-beta signaling pathway in colorectal cancer and determine the effects of its disruption on clinical behavior and outcome. MATERIALS AND METHODS: Smad proteins are the principal intracellular components of the TGF-beta signaling pathway. We conducted a high-throughput analysis of the expression patterns of Smad2, phosphorylated (activated) Smad2 (pSmad2), and Smad4 in more than 600 human colorectal cancer specimens assembled in tissue microarrays. RESULTS: The vast majority (93.8%; 95% CI: 92%-96%) of colorectal cancers expressed phosphorylated Smad2, indicating the ability of the tumors to survive and proliferate within a microenvironment that contains bioactive TGF-beta. Twelve of 633 (1.9%; 95% CI: 1%-3%) cases failed to express Smad2, and 15 of 641 (2.3%; 95% CI: 1%-4%) cases failed to express Smad4. Moreover, 29 of 615 (4.7%; 95% CI: 3%-7%) of cases expressed Smad2 but not its activated form (pSmad2), suggesting the presence of a TGF-beta receptor defect. Based on an analysis of 577 cases for which clinical outcome information was available, failure to express Smad2, pSmad2, or Smad4 was associated with advanced-stage disease, the presence of lymph node metastases, and a significantly shorter overall survival (median survival: 35 vs 58 months). DISCUSSION: Loss of Smad activation and/or expression occurs in approximately 10% of colorectal cancers. This subset has a poor prognosis because of its association with advanced disease and the presence of lymph node metastases at diagnosis.

Cell Division↗