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At least 289 records · Page 16Linked to original sources
PubMed2000

Validation of tissue microarray technology in breast carcinoma.

The recent development of tissue microarray technology has potentiated large-scale retrospective cohort studies using archival formalin-fixed, paraffin-embedded tissues. A major obstacle to broad acceptance of microarrays is that they reduce the amount of tissue analyzed from a whole tissue section to a disk, 0.6 mm in diameter, that may not be representative of the protein expression patterns of the entire tumor. In this study, we examine the number to disks required to adequately represent the expression of three common antigens in invasive breast carcinoma--estrogen receptor, progesterone receptor, and the Her2/neu oncogene--in 38 cases of invasive breast carcinoma. We compared the staining of 2 to 10 microarray disks and the whole tissue sections from which they were derived and determined that analysis of two disks is comparable to analysis of a whole tissue section in more than 95% of cases. To evaluate the potential for using archival tissue in such arrays, we created a breast cancer microarray of 8 to 11 cases from each decade beginning in 1932 to the present day and evaluated the antigenicity of these markers and others. This array demonstrates that many proteins retain their antigenicity for more than 60 years, thus validating their study on archival tissues. We conclude that the tissue microarray technique, with 2-fold redundancy, is a valuable and accurate method for analysis of protein expression in large archival cohorts.

Biomarkers, Tumor↗
PubMed2001

Effects of exercise on gene-expression profile in the rat hippocampus.

Exercise has beneficial effects on brain function, including the promotion of plasticity and the enhancement of learning and memory performance. Previously we found that exercise increases the expression of certain neurotrophic factors including brain derived neurotrophic factor in the rat hippocampus. To further explore the molecular mechanisms underlying these changes, we used high-density oligonucleotide microarrays containing probe sets representing approximately 5000 genes to analyze the level of gene transcripts in the hippocampus of rats voluntary running for 3 weeks in comparison with sedentary animals. An improved statistical approach for the analysis of DNA microarray data, Cyber-T, was utilized in data analysis. Here we show that exercise leads to changes in the level of a large number of gene transcripts, many of which are known to be associated with neuronal activity, synaptic structure, and neuronal plasticity. Our data indicate that exercise elicits a differential gene expression pattern with significant changes in genes of relevance for brain function.

Aging↗
PubMed2003

Distinct gene expression of osteopontin in patients with ulcerative colitis.

BACKGROUND: Ulcerative colitis (UC) is a multifactorial disorder of unknown etiology. Few studies have applied genome-wide gene expression analysis in colon tissue samples of UC. We report the analysis of mucosal gene expression in UC and noninflamed control specimens. MATERIALS AND METHODS: This study included 7 UC patients who received a total colectomy because of severe total colitis. Normal control colon tissues were obtained at least 10 cm from the area of pathology in 3 colon cancer patients. Ten colonic tissue samples (7 UC and 3 normal control samples) were subjected to high-density oligonucleotide array analysis. To compare differences in the level of gene expression between UC and control samples, Mann-Whitney U-test was used, with significance set at P < 0.05. RESULTS: Twenty-five genes had a 3.0 approximately 23.4-fold higher mRNA expression in UC samples compared with normal samples, whereas three genes had a 3.0 approximately 3.4-fold lower expression in UC samples compared with normal samples. Two genes showing more than a 10-fold increase expression in UC samples were a macrophage metalloelastase (L23808) and a osteopontin (AF052124). It has been said that macrophage metalloelastase is related to ulcer formation of the intestine, whereas osteopontin plays an important role in the pathogenesis of systemic lupus erythematosus and rheumatoid arthritis. CONCLUSION: Our present study supports the previous report that macrophage metalloelastase is related to ulcer formation of UC, and it also indicates the possibility that osteopontin plays an important role in the pathogenesis of UC via increased immune activity.

Adult↗
PubMed2002

An evaluation of tyramide signal amplification and archived fixed and frozen tissue in microarray gene expression analysis.

Archival formalin-fixed, paraffin-embedded and ethanol-fixed tissues represent a potentially invaluable resource for gene expression analysis, as they are the most widely available material for studies of human disease. Little data are available evaluating whether RNA obtained from fixed (archival) tissues could produce reliable and reproducible microarray expression data. Here we compare the use of RNA isolated from human archival tissues fixed in ethanol and formalin to frozen tissue in cDNA microarray experiments. Since an additional factor that can limit the utility of archival tissue is the often small quantities available, we also evaluate the use of the tyramide signal amplification method (TSA), which allows the use of small amounts of RNA. Detailed analysis indicates that TSA provides a consistent and reproducible signal amplification method for cDNA microarray analysis, across both arrays and the genes tested. Analysis of this method also highlights the importance of performing non-linear channel normalization and dye switching. Furthermore, archived, fixed specimens can perform well, but not surprisingly, produce more variable results than frozen tissues. Consistent results are more easily obtainable using ethanol-fixed tissues, whereas formalin-fixed tissue does not typically provide a useful substrate for cDNA synthesis and labeling.

Animals↗
PubMedDate not supplied

Differential gene expression between visceral and subcutaneous fat depots.

Abdominal obesity has been linked to the development of insulin resistance and Type 2 diabetes mellitus (DM2). By surgical removal of visceral fat (VF) in a variety of rodent models, we prevented insulin resistance and glucose intolerance, establishing a cause-effect relationship between VF and the metabolic syndrome. To characterize the biological differences between visceral and peripheral fat depots, we obtained perirenal visceral (VF) and subcutaneous (SC) fat from 5 young rats. We extracted mRNA from the fat tissue and performed gene array hybridization using Affymetrix technology with a platform containing 9 000 genes. Out of the 1 660 genes that were expressed in fat tissue, 297 (17.9 %) genes show a two-fold or higher difference in their expression between the two tissues. We present the 20 genes whose expression is higher in VF fat (by 3 - 7 fold) and the 20 genes whose expression is higher in SC fat (by 3 - 150 fold), many of which are predominantly involved in glucose homeostasis, insulin action, and lipid metabolism. We confirmed the findings of gene array expression and quantified the changes in expression in VF of genes involved in insulin resistance (PPARgamma leptin) and its syndrome (angiotensinogen and plasminogen activating inhibitor-1, PAI-1) by real-time PCR (qRT-PCR) technology. Finally, we demonstrated increased expression of resistin in VF by around 12-fold and adiponectin by around 4-fold, peptides that were not part of the gene expression platform. These results indicate that visceral fat and subcutaneous fat are biologically distinct.

Adipocytes↗
PubMed2002

Evaluation of the tissue microarray technique for immunohistochemical analysis in rectal cancer.

BACKGROUND: Immunohistochemical staining for tumor-associated proteins is widely used for the identification of novel prognostic markers. Recently, a tissue-conserving, high-throughput technique, tissue microarray, has been introduced. This technique uses 0.6-mm tissue core biopsy specimens, 500 to 1000 of which are brought into a new paraffin array block, which can be sectioned up to 100 times. METHODS: We evaluated the tissue microarray technique for immunohistochemical analysis in 20 rectal cancers. Immunohistochemical staining was performed for the proliferation marker Ki-67 and the tumor suppressor protein p53 in whole tissue sections and in tissue core biopsy specimens. RESULTS: The whole tissue sections were assessed by counting all cells in 10 high-power fields (x40), which resulted in a mean fraction of Ki-67-expressing tumor cells of 0.81 (range, 0.54-1.0). p53 expression assessed in whole tissue sections showed nuclear staining in 15 (75%) of 20 rectal carcinomas. For the tissue microarray technique, a median of 3 (range, 3-5) 0.6-mm tissue core biopsy specimens were studied from each of the 20 tumor specimens. The tissue microarray method gave a mean Ki-67 expression of 0.85 (range, 0.50-1.0) in tumor cell nuclei and showed p53 protein expression in the same 15 of 20 tumors as in the whole tissue sections. CONCLUSION: We conclude that the tissue microarray technique for immunohistochemical staining in rectal cancer yields staining of good quality and expression data for Ki-67 and p53 comparable to those obtained with whole tissue staining. The feasibility of tissue microarray thus enables time- and tissue-preserving studies of multiple markers in large tumor series.

Adult↗
PubMed2002

The distribution of caveolin-3 immunofluorescence in skeletal muscle fibre membrane defined by dual channel confocal laser scanning microscopy, fast Fourier transform and image modelling.

Membrane domains rich in caveolin-3 overlie sarcomeric actin in skeletal muscle. The membrane exhibits a regular array of caveolin-3 immunofluorescence using confocal laser scanning microscopy (CLSM). Fourier analysis of tissue imaged by CLSM accurately defines a repeating intensity with a long-axis spacing of 1.48 microm confirmed by measurement of direct images. Reverse fast Fourier transform (FFT) and image-modelling allow reconstruction of the pattern. Mathematical modelling has allowed replication of several features of the FFT, including the second order maxima that confirm the relatively high information content of the original images. Measurements of membrane-pattern primary long-axis spacings are consistent with our measurements of the I-band sarcomere repeat in similarly prepared specimens labelled with fluorescent phalloidin or imaged using differential interference contrast microscopy. Dual-channel CLSM analysis of the sarcomeric banding pattern of actin and the repeating pattern of muscle fibre membrane caveolin showed that caveolae overlie the I-band. The anti-caveolin immunofluorescence is deficient over the Z-disc and maximal toward each of the I-band extremities. A mechanism of membrane shape change in which membrane-lipid molecules are interposed between more stable anchored rafts associated with caveolae can be envisaged. Thus, increasing girth and reducing length of the sarcolemma in rapid contraction may be explained.

Animals↗
PubMed2002

Extensive and divergent circadian gene expression in liver and heart.

Many mammalian peripheral tissues have circadian clocks; endogenous oscillators that generate transcriptional rhythms thought to be important for the daily timing of physiological processes. The extent of circadian gene regulation in peripheral tissues is unclear, and to what degree circadian regulation in different tissues involves common or specialized pathways is unknown. Here we report a comparative analysis of circadian gene expression in vivo in mouse liver and heart using oligonucleotide arrays representing 12,488 genes. We find that peripheral circadian gene regulation is extensive (> or = 8-10% of the genes expressed in each tissue), that the distributions of circadian phases in the two tissues are markedly different, and that very few genes show circadian regulation in both tissues. This specificity of circadian regulation cannot be accounted for by tissue-specific gene expression. Despite this divergence, the clock-regulated genes in liver and heart participate in overlapping, extremely diverse processes. A core set of 37 genes with similar circadian regulation in both tissues includes candidates for new clock genes and output genes, and it contains genes responsive to circulating factors with circadian or diurnal rhythms.

Animals↗
PubMed2002

Extraction and amplification of DNA from formalin-fixed, paraffin-embedded tissues.

Formalin-fixed, paraffin-embedded tissue (PET) is an invaluable resource for retrospective molecular genetic studies, but the extraction of high-quality genomic DNA from the PET may be problematic. We report a simple method that significantly improves the ability to amplify DNA recovered from formalin-fixed PET. Based on the standard procedure of a commercially available DNA preparation kit, the QIAamp DNA mini kit or the HighPure DNA preparation kit, we developed this method by eliminating the xylene/ethanol extraction step and adding a heat-treatment step. With this method, we have observed a five- to 10-fold increase in amplification efficiency of a fragment in a range of 90 to 386 base pairs. We also have obtained much higher amplification efficiencies for a multiplex polymerase chain reaction.

Base Sequence↗
PubMed2003

Real-time quantitative RT-PCR of cyclin D1 mRNA in mantle cell lymphoma: comparison with FISH and immunohistochemistry.

Presence of the balanced translocation t(11;14)(q13;q32) and the consequent overexpression of cyclin D1 found in mantle cell lymphoma (MCL) has been shown to be of important diagnostic value. Although many molecular and immunohistochemical approaches have been applied to analyze cyclin D1 status, correlative studies to compare different methods for the diagnosis of MCL are lacking. In this study, we examined 39 archived paraffin specimens from patients diagnosed with a variety of lymphoproliferative diseases including nine cases meeting morphologic and immunophenotypic criteria for MCL by: (1) real-time quantitative RT-PCR to evaluate cyclin D1 mRNA expression; (2) dual fluorescence in situ hybridization (FISH) to evaluate the t(11;14) translocation in interphase nuclei; and (3) tissue array immunohistochemistry to evaluate the cyclin D1 protein level. Among the nine cases of possible MCL, seven cases showed overexpression of cyclin D1 mRNA (cyclin D1 positive MCL) and two cases showed no cyclin D1 mRNA increase (cyclin D1 negative "MCL-like"). In six of seven cyclin D1 positive cases, the t(11;14) translocation was demonstrated by FISH analysis; in one case FISH was unsuccessful. Six of the seven cyclin D1 mRNA overexpressing cases showed increased cyclin D1 protein on tissue array immunohistochemistry; one was technically suboptimal. Among the two cyclin D1 negative MCL-like cases, FISH confirmed the absence of the t(11;14) translocation in both cases. All other lymphoproliferative diseases studied were found to have low or no cyclin D1 mRNA expression and were easily distinguishable from the cyclin D1 overexpressing MCLs by all three techniques. In addition, to confirming the need to assess cyclin D1 status, as well as, morphology and immunophenotyping to establish the diagnosis of MCL, this study demonstrates good correlation and comparability between measure of cyclin D1 mRNA, the 11;14 translocation and cyclin D1 protein.

Cyclin D1↗
PubMed2003

Tissue inhibitor of metalloproteinase-3 downregulation in lymphangioleiomyomatosis: potential consequence of abnormal serum response factor expression.

Pulmonary lymphangioleiomyomatosis (LAM) is characterized by abnormal smooth muscle-like cell proliferation leading to tissue destruction and cyst formation. We demonstrate that serum response factor (SRF), a critical smooth muscle transcription factor, is overexpressed in LAM cells. To determine whether abnormal SRF levels might have a pathogenic role in LAM, we transfected SRF into mouse lung fibroblasts and performed a cDNA array analysis. High SRF level upregulated the expression of matrix metalloproteinase (MMP)-2 and MMP-14, two MMPs previously shown to be increased in LAM. In addition, SRF down-regulated tissue inhibitor of metalloproteinase (TIMP)-3, one of their inhibitors. TIMP-3 inhibition was further confirmed by reverse transcriptase/polymerase chain reaction, immunoblotting, and immunostaining of human lung fibroblasts transfected with SRF fused to DsRed2 (a red variant of green fluorescent protein). To determine the in vivo significance of our findings, we immunostained 12 LAM cases for TIMP-3. In eight of them, TIMP-3 was ubiquitously present in normal lung parenchyma, but it was absent in LAM lesions. In the remaining cases, including two out of five normal control lungs, the antibody immunoreacted exclusively with elastin, probably due to suboptimal tissue processing. Because timp-3-null mice develop spontaneous emphysema, our findings suggest that SRF-mediated TIMP-3 inhibition might contribute to the tissue damage seen in LAM.

Animals↗
PubMed2001

Gene expression abnormalities in human glial tumors identified by gene array.

Novel genes specific for human oligodendroglioma and glioblastoma multiforme (GBM) were detected using the gene array analysis [18,376 genes Gene Discovery Array (GDA) from Incyte Genomics, Inc.]. Eleven genes were chosen based on the highest ratios of differential expression identified by GDA between histologically normal adjacent tissue and brain tumor tissue. The differential expression of those 11 genes was verified by semiquantitative RT-PCR and Northern analysis on 22 samples of glial and other tumors of the brain, as well as of normal embryonic and adult brain tissue. Gene no. 5 (an EST) was more expressed by GDA analysis in histologically normal adjacent brain tissue than in the corresponding oligodendroglioma. By RT-PCR, this gene was expressed in a number of brain tumors but not in normal adult and embryonic brain. By GDA analysis, gene no. 7 (oligophrenin-1) gave the highest ratio compared to other genes in brain tissue adjacent to the GBM vs. GBM. By RT-PCR, oligophrenin-1 was expressed in tumors and tumor-adjacent tissue, whereas meningioma and corpus callosum were negative. Gene no. 11 (an EST) was expressed only in brain tumors but not in normal brain by Northern analysis (message size 1.5 kb) and RT-PCR. GDA analysis successfully identified genes preferentially expressed in brain tumors, which was confirmed by Northern analysis and semiquantitative RT-PCR. The validity of gene arrays for tumor-specific gene discovery is discussed. Study of differential gene expression in glial tumors should help identify the mechanism/s of transformation of normal glial cells to malignant.

Brain Neoplasms↗
PubMed2002

Retriever and CompareTable, two informatics tools for data analysis of high-density oligonucleotide arrays.

High-density oligonucleotide arrays are widely employed for detecting global changes in gene expression profiles of cells or tissues exposed to specific stimuli. Presented with large amounts of data, investigators can spend significant amounts of time analyzing and interpreting this array data. In our application of GeneChip arrays to analyze changes in gene expression in viral-infected epithelium, we have needed to develop additional computational tools that may be of utility to other investigators using this methodology. Here, I describe two executable programs to facilitate data extraction and multiple data point analysis. These programs run in a virtual DOS environment on Microsoft Windows 95/98/2K operating systems on a desktop PC. Both programs can be freely downloaded from the BioTechniques Software Library (www.BioTechniques.com). The first program, Retriever, extracts primary data from an array experiment contained in an Affymetrix textfile using user-inputted individual identification strings (e.g., the probe set identification numbers). With specific data retrieved for individual genes, hybridization profiles can be examined and data normalized. The second program, CompareTable, is used to facilitate comparison analysis of two experimental replicates. CompareTable compares two lists of genes, identifies common entries, extracts their data, and writes an output text file containing only those genes present in both of the experiments. The output files generated by these two programs can be opened and manipulated by any software application recognizing tab-delimited text files (e.g., Microsoft NotePad or Excel).

Computational Biology↗
PubMed2001

Gene expression profile analysis by DNA microarrays: promise and pitfalls.

DNA microarrays represent a technological intersection between biology and computers that enables gene expression analysis in human tissues on a genome-wide scale. This application can be expected to prove extremely valuable for the study of the genetic basis of complex diseases. Despite the enormous promise of this revolutionary technology, there are several issues and possible pitfalls that may undermine the authority of the microarray platform. We discuss some of the conceptual, practical, statistical, and logistical issues surrounding the use of microarrays for gene expression profiling. These issues include the imprecise definition of normal in expression comparisons; the cellular and subcellular heterogeneity of the tissues being studied; the difficulty in establishing the statistically valid comparability of arrays; the logistical logjam in analysis, presentation, and archiving of the vast quantities of data generated; and the need for confirmational studies that address the functional relevance of findings. Although several complicated issues must be resolved, the potential payoff remains large.

Gene Expression Profiling↗
PubMed2000

Gene expression profiles of human endometrial cancer samples using a cDNA-expression array technique: assessment of an analysis method.

The recently developed cDNA expression array technique can be used to generate gene-expression fingerprints of tumour specimens. To gain insight into molecular mechanisms involved in the development and progression of cancer, this cDNA expression array technique could be a useful tool, however, no established methods for interpreting the results are yet available. We used the Atlas cancer cDNA expression array (Clontech, USA) for analysing total RNA isolated from four human endometrial carcinoma samples (two cell-lines and two tissue samples), one benign endometrial tissue sample and a human breast cancer cell-line, in order to develop a method for analysing the array data. The obtained gene-expression profiles were highly reproducible. XY-scatterplots and regression analysis of the logarithmic transformed data provided a practical method to analyse the data without the need of preceding normalization. Three genes (Decorin, TIMP3 and Cyclin D1) were identified to be differentially expressed between the benign endometrial tissue sample and the endometrial carcinoma samples (tissue and cell-lines). These three genes may potentially be involved in cancer progression. A higher degree of similarity in gene-expression profile was found between the endometrial samples (tissue and cell-lines) than between the endometrial samples and the breast cancer cell-line, which is indicative for an endometrial tissue-specific gene-expression profile.

DNA, Complementary↗
PubMed2003

Database for renal collecting duct regulatory and transporter proteins.

The mammalian kidney collecting duct plays an important role in the fine regulation of Na, K, water, and acid-base balance. Functional genomic and proteomic studies of the kidney offer new opportunities in the understanding of renal physiology and pathophysiology, and the collecting duct is an appropriate target tissue because of the relative simplicity of its cells and the ease of isolating or culturing large numbers of collecting duct cells. Study of the collecting duct includes assessment of gene expression and protein regulation and abundance. For example, DNA and protein microarrays can be used to quantitate gene expression and protein regulation and abundance under varying physiological conditions. An Internet-accessible database has been devised for major collecting duct proteins involved in transport and regulation of cellular processes. The individual proteins included in this database are those culled from literature searches and from previously published studies involving cDNA arrays and serial analysis of gene expression (SAGE). Design of microarray targets for the study of kidney collecting duct tissues is facilitated by the database, which includes links to curated base pair and amino acid sequence data, relevant literature, and related databases. Use of the database is illustrated by a search for water channel proteins, aquaporins, and by a subsequent search for vasopressin receptors. Links are shown to the literature and to sequence data for human, rat, and mouse, as well as to relevant web-based resources. Extension of the database is dynamic and is done through a maintenance interface. This permits creation of new categories, updating of existing entries, and addition of new ones.

Animals↗
PubMed2003

[Aspiration biopsy RNA diagnosis].

Recent advances in molecular-based techniques, especially RNA analyses such as differential display, serial analysis of gene expression(SAGE) and DNA arrays, have enabled us to detect the specific changes in mRNA in cancer tissues rapidly and easily. We have established a new method of preoperative molecular-based diagnosis of thyroid carcinomas, one of the most common cancers in females. This technique, Aspiration Biopsy RNA Diagnosis, ABRD, allows us to perform preoperative RNA analysis of the tumors by extracting RNA from tumor cells obtained by fine needle aspiration biopsies(FNABs). For example, by ABRD detection of oncofetal fibronectin or calcitonin mRNA in FNABs, three types of thyroid carcinomas, papillary, anaplastic and medullary carcinomas, were accurately diagnosed preoperatively without the help of cytological or pathological examinations by a skillful pathologist. Further, by real-time monitoring RT-PCR measuring the expression levels of these cancer-specific mRNAs, a fully automated system was established. Because ABRD can be performed without any severe invasion to the patients, in the near future, when more reliable systems of quantitative RNA analysis are developed, ABRD will probably become one of the standard tests for preoperative diagnosis of cancer.

Biopsy, Needle↗
PubMed2001

Web-based tissue microarray image data analysis: initial validation testing through prostate cancer Gleason grading.

Tissue microarray technology promises to enhance tissue-based molecular research by allowing improved conservation of tissue resources and experimental reagents, improved internal experimental control, and increased sample numbers per experiment. Organized, well-validated collection and analysis of the voluminous image data produced by tissue microarray technology is critical to maximize its value. Web-based technology for visual analysis and searchable storage of microarray image data could provide optimal flexibility for research groups in meeting this goal, but this approach has not been examined scientifically. Toward this goal, a prostate tissue microarray block containing 432 tissue cores (0.6 mm diameter) was constructed. Moderately compressed (200 kb).jpg images of each tissue spot were acquired and were saved using a naming convention developed by the SPORE Prostate Tissue Microarray Collaborative Group. Four hundred three tissue array spot images were uploaded into a database developed for this study and were converted to.fpx format to decrease Internet transmission times for high-resolution image data. In phase I of the image analysis portion of the study, testing and preliminary analysis of the Web technology was performed by 2 pathologists (M.A.R. and G.S.B.). In phase II, 2 pathologists (J.I.E. and T.M.W.) with no previous exposure to this technology and no knowledge of the structure of the study were presented a set of 130 sequential tissue spot images via the Web on their office computers. In phase III, the same pathologists were presented a set of 193 images, including all 130 from phase II and 63 others, with image presentation order randomized. With each zoomable tissue spot image, each pathologist was presented with a nested set of questions regarding overall interpretability of the image, presence or absence of cancer, and predominant and second most frequent Gleason grade. In phases II and III of the study, 319 of 323 (99%) image presentations using this Web technology were rated interpretable. Comparing the 2 pathologists' readings in phases II and III, Gleason grade determinations by each pathologist were identical in 179 of 221 (81%) determinations and were within 1 point of each other in 221 of 221 (100%) determinations, a performance rate similar to if not better than that previously reported for direct microscopic Gleason grading. Interobserver comparison of Gleason score determinations and intraobserver comparisons for Gleason grade and score also showed a pattern of uniformity similar to those reported in direct microscope-based Gleason grading studies. Interobserver (7.5%) and intraobserver (5% and 3%) variability in determining whether diagnosable cancer was present point out the existence of a "threshold effect" that has rarely been studied but may provide a basis for identification of features that are most amenable to improved diagnostic standardization. In summary, storage and analysis of tissue microarray spot images using Web-based technology is feasible and practical, and the quality of images obtained using the techniques described here appears adequate for most tissue-based pathology research applications. HUM PATHOL 32:417-427.

Databases, Factual↗