An international database and integrated analysis tools for the study of cancer gene expression.

Researchers working collaboratively in Brazil and the United States have assembled an International Database of Cancer Gene Expression. Several strategies have been employed to generate gene expression data including expressed sequence tags (ESTs), serial analysis of gene expression (SAGE), and open reading-frame expressed sequence tags (ORESTES). The database contains six million gene tags that reflect the gene expression profiles in a wide variety of cancerous tissues and their normal counterparts. All sequences are deposited in the public databases, GenBank and SAGEmap. A suite of informatics tools was designed to facilitate in silico analysis of the gene expression datasets and are available through the NCI Cancer Genome Anatomy Project web site (http://cgap.nci.nih.gov).

In silico analysis of cancer through the Cancer Genome Anatomy Project.

The Cancer Genome Anatomy Project (CGAP) was designed and implemented to provide public datasets, material resources and informatics tools to serve as a platform to support the elucidation of the molecular signatures of cancer. This overview of CGAP describes the status of this effort to develop resources based on gene expression, polymorphism identification and chromosome aberrations, and we describe a variety of analytical tools designed to facilitate in silico analysis of these datasets.

Sequence databases and microarrays as tools for identifying prostate cancer biomarkers.

Identification, acquisition, and assessment of molecular markers that could be adopted as surrogate endpoints for evaluating a response to prostate cancer intervention strategies is highly desirable. Recent advances in the fields of genomics and biotechnology have dramatically increased the quantity and accessibility of molecular information that is relevant to the study of prostate carcinogenesis. One major advance involves the construction of comprehensive databases that archive gene sequences and gene expression data. This information is in a format suitable for virtual queries designed to distinguish the molecular differences between normal and cancer cells. A second major advance uses robotic tools to construct microarrays comprising thousands of distinct genes expressed in prostate tissues. Such arrays offer a powerful approach for monitoring the expression of thousands of genes simultaneously and provide access for techniques designed to assess patterns or "fingerprints" of gene expression that may ultimately be used as signatures of response to therapeutic intervention.

Surface-activated bovine platelets do not spread, they unfold.

The present study has examined the response of bovine platelets to surface activation and compared it to the reaction of human cells. Human platelets react to surfaces by losing their discoid shape, extending pseudopods, converting to dendritic forms, and finally, spreading into thin films resembling pancakes. Bovine platelets do not spread, they unfold. Surface activation causes them to transform from discs to irregular, flattened shapes resembling dendritic platelets, but they are unable to fill in spaces between pseudopods, a step required for spreading. Bovine platelets lack the surface-connected open canalicular system (OCS), which serves as a reservoir of membrane for human platelet spreading. Its absence may be the major factor in the failure of bovine platelet spreading, but there are other possible factors. Circumferential microtubules are more resistant to disassembly in surface-activated bovine than human cells, and their stability as rings or fractured bundles may limit spreading. Actin filament assembly is similar in human and bovine platelets, but the organization is different. Human platelets form a peripheral weave of actin that expands the membrane between pseudopods. A peripheral weave does not form in surface-activated bovine platelets. The absence of the OCS and differences in cytoskeletal organization in bovine platelets may also affect spreading of the surface membrane. Fibrinogen-gold (Fgn-Au) probes added to spread human platelet move from pseudopods and the cell margin toward the center and concentrate in the OCS. Fgn-Au particles bind to surface-activated bovine cells, but move very little, or not at all. All of these factors may contribute to the inability of bovine platelets to react to surfaces by spreading like human cells, but absence of the OCS appears to be the major cause.

Gold-labeled bovine fibrinogen for study of human platelets.

Fibrinogen coupled to colloidal gold has proven to be a useful agent for probing the glycoprotein IIb-IIIa receptor on human and bovine platelets at the ultrastructural level. The reagent has helped to demonstrate fundamental differences in the reorganization of the fibrinogen receptors on human and cattle platelets following surface activation. However, commercial preparations of human fibrinogen have not yielded a stable reagent in our hands when coupled to colloidal gold. The present study has substituted bovine for human fibrinogen. Bovine fibrinogen gold proved to be a more stable reagent and could be substituted for human fibrinogen gold in all experiments on human and bovine platelets.

Cysteamine blocks somatostatin secretion without altering the course of insulin or glucagon release. A new model for the study of islet function.

Cysteamine (300 mg/kg) administered subcutaneously depletes pancreatic somatostatin to 36% of control levels, but does not alter pancreatic insulin or glucagon content. Although perfusion of pancreata from normal animals with glucose (300 mg/dl) markedly stimulated somatostatin release, pancreata from cysteamine-treated animals failed to secrete somatostatin in response to glucose. Cysteamine treatment was without effect on insulin and glucagon release under the conditions tested. The isolated perfused pancreas from the cysteamine-treated rat provides a model for further investigations into regulation of islet hormone release in the absence of stimulated somatostatin release.

Effect of muscimol on glucose-stimulated somatostatin and insulin release from the isolated, perfused rat pancreas.

This study examines the effect of muscimol, a high affinity, specific gamma-aminobutyric acid (GABA) agonist, on glucose-stimulated somatostatin and insulin release from the isolated, perfused rat pancreas. Perfusion with low glucose (50 mg/dl) conditions resulted in basal somatostatin release of 46 +/- 4 pg/ml. Basal insulin release was less than 20 microU/ml. High glucose (300 mg/dl) conditions stimulated somatostatin and insulin release. Steady-state levels of somatostatin and insulin release under high glucose conditions were 425 +/- 12 pg/ml and 419 +/- 18 microU/ml, respectively. Perfusion with medium containing 1 microM muscimol inhibited glucose-stimulated somatostatin release by 38%, whereas the course of glucose-stimulated insulin release was unaffected. Tentative conclusions from this study are (1) that GABA is potentially a modulator of islet somatostatin but not insulin release, and (2) the fact that somatostatin, an inhibitor of insulin, can be suppressed 38% without coincidental increase in insulin release seems to indicate that, under high glucose conditions, somatostatin is without a significant paracrine effect on the beta-cells.