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At least 163 records · Page 9Linked to original sources

Genetic profiling of chromosome 1 in breast cancer: mapping of regions of gains and losses and identification of candidate genes on 1q.

Chromosome 1 is involved in quantitative anomalies in 50-60% of breast tumours. However, the structure of these anomalies and the identity of the affected genes remain to be determined. To characterise these anomalies and define their consequences on gene expression, we undertook a study combining array-CGH analysis and expression profiling using specialised arrays. Array-CGH data showed that 1p was predominantly involved in losses and 1q almost exclusively in gains. Noticeably, high magnitude amplification was infrequent. In an attempt to fine map regions of copy number changes, we defined 19 shortest regions of overlap (SROs) for gains (one at 1p and 18 at 1q) and of 20 SROs for losses (all at 1p). These SROs, whose sizes ranged from 170 kb to 3.2 Mb, represented the smallest genomic intervals possible based on the resolution of our array. The elevated incidence of gains at 1q, added to the well-established concordance between DNA copy increase and augmented RNA expression, made us focus on gene expression changes at this chromosomal arm. To identify candidate oncogenes, we studied the RNA expression profiles of 307 genes located at 1q using a home-made built cDNA array. We identified 30 candidate genes showing significant overexpression correlated to copy number increase. In order to substantiate their involvement, RNA expression levels of these candidate genes were measured by quantitative (Q)-RT-PCR in a panel of 25 breast cancer cell lines previously typed by array-CGH. Q-PCR showed that 11 genes were significantly overexpressed in the presence of a genomic gain in these cell lines, and 20 overexpressed when compared to normal breast.

Breast Neoplasms↗

Genetic profile of acute myeloid leukemia.

Understanding genomic events and the cascade of their effects in cell function is crucial for identifying distinct subsets of acute myeloid leukemia and developing new therapeutic strategies. Conventional cytogenetics, fluorescence in situ hybridization investigations and molecular studies have provided much information over the past few years. This review will focus on major genomic mechanisms in acute myeloid luekemia and on the genes implicated in the pathogenesis of specific subtypes.

Acute Disease↗

Genetic profiling of human hepatocellular carcinoma.

The underlying molecular basis for the heterogeneity in human liver cancer, hepatocellular carcinoma (HCC), is largely unknown. As with most other human cancers, the heterogeneous nature of HCC has hampered both treatment and prognostic predictions. Global gene expression profiling of human cancers is a promising new technology for refining the diagnosis and prognosis of HCC as well as for identifying potential therapeutic targets. Improved molecular characterization of HCC from gene expression profiling studies will undoubtedly improve the prediction of treatment responses, improve the selection of treatments for specific molecular subtypes of HCC, and ultimately improve the clinical outcome of HCC patients. We review the recent advances in gene expression profiling of HCC and discuss the biological and clinical insights obtained from these studies.

Animals↗

Atypical enteropathogenic Escherichia coli strains: phenotypic and genetic profiling reveals a strong association between enteroaggregative E. coli heat-stable enterotoxin and diarrhea.

The virulence profiles of most atypical enteropathogenic Escherichia coli (EPEC) strains are unknown. A total of 118 typical and atypical strains of EPEC serotypes and non-EPEC serogroups isolated from children with or without acute diarrhea who were from different cities in Brazil were examined for virulence-associated markers and adherence to HEp-2 cells, and also had random amplified polymorphic DNA (RAPD) analysis performed. Atypical strains were identical to typical strains with regard to the virulence factors encoded on the locus of enterocyte effacement (LEE). In contrast with typical EPEC strains, none of the atypical strains reacted with the bfpA probe, and half of the strains hybridized with the perA probe. Most atypical strains presented Tir sequences that correlated with enteropathogenic or enterohemorrhagic E. coli (98%), had LEE inserted in either selC or pheU (88%), and presented a typeable intimin (52%). Eighteen new serotypes were found in the EPEC strains. Atypical and typical EPEC strains belonged to different RAPD clusters. Most atypical strains showed a localized-like adherence pattern (61.5%). Of the non-LEE-encoded virulence factors, enteroaggregative E. coli heat-stable enterotoxin was noted most frequently (45%) and was significantly associated with diarrhea (P=.01). Thus, this virulence marker may be used as an additional tool for the diagnosis of truly atypical pathogenic strains.

Bacterial Toxins↗

Genetic profiling of Gleason grade 4/5 prostate cancer: which is the best prostatic control tissue?

PURPOSE: We examined the variation in gene expression profiles of prostate cancer caused by zone specific genes. MATERIALS AND METHODS: Ten normal central zone, 10 transition zone (benign prostatic hyperplasia) and 6 normal peripheral zone tissues from radical retropubic prostatectomies were compared to each other and to 12 peripheral zone Gleason grade 4/5 cancers. Test chips and HuGeneFL6800 (Affymetrix, Inc., Santa Clara, California) chips were used to assay the transcribed genes. Data were obtained with the Microarray Suite Version 4.0.1 (Affymetrix, Inc.) and analyzed statistically. RESULTS: Substantially different gene expression profiles were found depending upon which of the 3 zonal tissues were used as a control. All 3 profiles were compared for efficiency (ability to locate genes) and for robustness (the magnitude of difference between the control and the Gleason grade 4/5 tissue). Microscopically normal appearing peripheral zone tissue at the gene level shows many characteristics of Gleason grade 4/5 cancer. CONCLUSIONS: Gene expression profiles of prostate cancer are affected by the zonal location of the control tissue and the cancer.

Down-Regulation↗

Prevalence, serotype distribution, antibiotic susceptibility and genetic profiles of mesophilic Aeromonas species isolated from hospitalized diarrhoeal cases in Kolkata, India.

A comprehensive study was performed to examine incidence, species distribution, drugs sensitivity, virulence genes and molecular fingerprints of Aeromonas species isolated from patients with acute diarrhoea over a period of 2 years in Kolkata, India. Following the Aerokey II scheme, more than 95 % of strains were identified to species level. Seven different species were encountered in this study, with Aeromonas caviae being dominant, followed by Aeromonas hydrophila and Aeromonas veronii biovar sobria. Thirty different serotypes were encountered, with O16, O83 and O85 being dominant, but no serotype was associated specifically with a single species. The majority of Aeromonas strains exhibited multidrug resistance. The alt and act genes, which encode heat-labile cytotonic and cytotoxic enterotoxins, were respectively found in 71.9 and 20.1 % of strains examined. Only 2.4 % of strains carried the heat-stable cytotonic enterotoxin (ast) gene. The hlyA gene was found in 28 % of Aeromonas strains. With few exceptions, genomic diversity of Aeromonas strains belonging to the same serotype was observed by random amplification of polymorphic DNA PCR and ribotyping. Different species of Aeromonas and different clones of Aeromonas species seem to be associated with hospitalized cases of diarrhoea in Kolkata, India.

Aeromonas↗

Identification of Sample Processing Errors in Microbiome Studies Using Host Genetic Profiles.

In microbiome studies, sample processing errors are frequent and difficult to detect, especially in large studies involving multiple sites, personnel, and sample types. We present two complementary approaches to identify such errors using host DNA profiled via metagenomic sequencing of microbiome samples. The first approach compares host SNPs inferred from metagenomics to independently obtained genotypes (e.g., microarray genotypes) to match samples to their donors, while the second method compares metagenomics-inferred SNPs between samples to identify samples supplied by the same donor. Furthermore, we demonstrate that combining these methods with experimental metadata provides greater confidence in the identification of errors. Analyzing a longitudinal vaginal microbiome dataset, we demonstrate the ability of our approach to identify mislabeled samples. Using subsampling, we further show that our methods are robust to low sequencing coverage. Overall, our analysis highlights the frequency of processing errors in microbiome studies. We therefore recommend applying error-detection methods in all studies with suitable data.

Journal Article↗

Genetic profiling of dendritic cells exposed to live- or ultraviolet-irradiated Chlamydia muridarum reveals marked differences in CXC chemokine profiles.

Chlamydia trachomatis is a major cause of sexually transmitted disease worldwide for which an effective vaccine is being actively pursued. Current vaccine efforts will be aided by elucidating the interaction between Chlamydia and dendritic cells (DCs). Protective immunity appears to develop slowly following natural infection in humans, and early vaccine trials using inactivated C. trachomatis resulted in partial, short-lived protection with possible enhanced inflammatory pathology during re-infection. Thus, immunity following natural infection with live chlamydia may differ fundamentally from immune responses induced by immunization with inactivated chlamydia. We explored this conjecture by studying the response of DCs exposed to either viable or inactivated [ultraviolet (UV) -irradiated] chlamydia elementary bodies (EBs; designated as Live-EB and UV-EB, respectively) using Affymetrix GeneChip microarrays. Thirty-one immunologically characterized genes were differentially expressed by DCs following exposure to Live-EB or UV-EB, including two glutamic acid-leucine-arginine cysteine-X-cysteine (ELR CXC) neutrophil chemoattractant chemokines, Cxcl1 (KC), and Cxcl2 (MIP-2). Up-regulation of these genes by Live-EB as compared to UV-EB was verified by quantitative reverse transcription-polymerase chain reaction and increased chemokine secretion was confirmed by enzyme-linked immunosorbent assay both in vitro and in vivo. Immunofluorescence and fluorescence-activated cell sorter analysis of chlamydia-infected lung tissue confirmed that Live-EB but not UV-EB induced significant DC and neutrophil infiltration during infection. These observations demonstrate that the development of an antichlamydial immune response is dramatically influenced by chlamydial viability. This has implications as to why early inactivated chlamydial vaccines were ineffective and suggests that new vaccine design efforts may benefit from in vitro DC screening for ELR chemokine expression profiles.

Animals↗

Genetic profiling of aortic allografts: prothymosin alpha as potential target?

Transplant arteriosclerosis is the result of intima proliferation in large vessels upon organ transplantation. Obliteration of the vascular lumen will ultimately lead to ischemia and late graft failure. Gene array analysis was performed to identify factors involved in the pathogenesis of transplant arteriosclerosis. Aortic transplants from Dark Agouti to Wistar Furth rats were performed to identify potential target genes. Hierarchical clustering of genes specifically upregulated in allogeneic but not in syngeneic aortas revealed 19 genes. A gene that fulfilled these criteria is prothymosin alpha (PTMA), a regulator of estrogen receptor transcriptional activity. PTMA gene and protein expression levels were confirmed by PCR and immunohistochemistry. Estrogen receptor staining was increased in allogeneic aortas. Furthermore, cyclin D1 a downstream target of PTMA, was also up regulated in allogeneic aortas. In conclusion, PTMA was identified as potential candidate gene involved in transplant arteriosclerosis.

Animals↗

Tailored therapy to fit individual profiles. Genetics and coronary artery disease.

In the twentieth century, coronary artery disease (CAD) was the major cause of morbidity and mortality in western societies. Genetics and environmental influences clearly contribute to CAD. Our genetic makeup contributes to not only coronary risk factors, but also determines an individual's response to environmental challenges such as diet, drugs, and tobacco. Genetic testing is likely to be more predictive of our predisposition to CAD than current conventional testing of known risk factors. Therapy aimed at altering the regulation of genes or their transcribed proteins may prove appropriate in individual patients, depending on their genetic background. The understanding of our genetic predisposition to CAD may enable targeted environmental modification strategies aimed at individuals at greatest risk. Both in terms of the huge costs of drugs to society and in terms of needless medicalization, genotyping in order to tailor therapy might become a routine part of risk management earlier than we think.

Angioplasty, Balloon, Coronary↗

Genetic profiling of alpha 1-adrenergic receptor subtypes by oligonucleotide microarrays: coupling to interleukin-6 secretion but differences in STAT3 phosphorylation and gp-130.

Alpha(1)-adrenoceptor subtypes (alpha(1A)-, alpha(1B)-, alpha(1D)-) are known to couple to similar signaling pathways, although differences among the subtypes do exist. As a more sensitive assay, we used oligonucleotide microarrays to identify gene expression changes in Rat-1 fibroblasts stably expressing each individual subtype. We report the gene expressions that change by at least a factor of 2 or more. Gene expression profiles significantly changed equally among all three subtypes, despite the unequal efficacy of the inositol phosphate response. Gene expressions were clustered into cytokines/growth factors, transcription factors, enzymes, and extracellular matrix proteins. There were also a number of individual subtype-specific changes in gene expression, suggesting a link to independent pathways. In addition, all three alpha(1)-AR subtypes robustly stimulated the transcription of the prohypertrophic cytokine interleukin (IL)-6, but differentially altered members of the IL-6 signaling pathway (gp-130 and STAT3). This was confirmed by measurement of secreted IL-6, activated STAT3, and gp-130 levels. Activation of STAT3 Tyr705 phosphorylation by the alpha(1)-ARs was not through IL-6 activation but was synergistic with IL-6, suggesting direct effects. Interestingly, alpha(1B)-AR stimulation caused the dimerization-dependent phosphorylation of Tyr705 on STAT3 but did not activate the transcriptional-dependent phosphorylation of Ser727. The alpha(1B)-AR also constitutively down-regulated the protein levels of gp-130. These results suggest that the alpha(1B)-AR has differential effects on the phosphorylation status of the STAT3 pathway and may not be as prohypertrophic as the other two subtypes.

Animals↗

Use of genetic profiling in leprosy to discriminate clinical forms of the disease.

Leprosy presents as a clinical and immunological spectrum of disease. With the use of gene expression profiling, we observed that a distinction in gene expression correlates with and accurately classifies the clinical form of the disease. Genes belonging to the leukocyte immunoglobulin-like receptor (LIR) family were significantly up-regulated in lesions of lepromatous patients suffering from the disseminated form of the infection. In functional studies, LIR-7 suppressed innate host defense mechanisms by shifting monocyte production from interleukin-12 toward interleukin-10 and by blocking antimicrobial activity triggered by Toll-like receptors. Gene expression profiles may be useful in defining clinical forms of disease and providing insights into the regulation of immune responses to pathogens.

Algorithms↗

Nonradioactive method to study genetic profiles of natural bacterial communities by PCR-single-strand-conformation polymorphism.

We describe a new method for studying the structure and diversity of bacterial communities in the natural ecosystem. Our approach is based on single-strand-conformation polymorphism (SSCP) analysis of PCR products of 16S rRNA genes from complex bacterial populations. A pair of eubacterial universal primers for amplification of the variable V3 region were designed from the 16S rRNA sequences of 1,262 bacterial strains. The PCR conditions were optimized by using genomic DNAs from five gram-positive and seven gram-negative strains. The SSCP analysis of the PCR products demonstrated that a bacterial strain generated its characteristic band pattern and that other strains generated other band patterns, so that the relative diversity in bacterial communities could be measured. In addition, this method was sensitive enough to detect a bacterial population that made up less than 1.5% of a bacterial community. The distinctive differences between bacterial populations were observed in an oligotrophic lake and a eutrophic pond in a field study. The method presented here, using combined PCR amplification and SSCP pattern analyses of 16S rRNA genes, provides a useful tool to study bacterial community structures in various ecosystems.

Bacteria↗

Genetic profiling of the oral microbiota associated with severe early-childhood caries.

The determination of the composition of the microbial community in the oral cavity is usually based on cultivation methods; however, nearly half of the bacteria in the saliva and the dental plaque are not cultivable. In this study, we evaluated the difference in oral microbial diversity between children with severe early-childhood caries (S-ECC) and caries-free (CF) controls by means of a cultivation-independent approach called denaturing gradient gel electrophoresis (DGGE). Pooled dental plaque samples were collected from 20 children aged 2 to 8 years. Total microbial genomic DNA was isolated from those subjects, and a portion of the 16S rRNA gene locus was PCR amplified by using universal primers. We observed that the mean species richness of the bacterial population was greater in the CF children (n = 12) (42 +/- 3.7) than in the S-ECC children (n = 8) (35 +/- 4.3); the difference was statistically significant (P = 0.005). The overall diversity of plaque samples as measured by the Shannon index was 3.5 for the S-ECC group and 3.7 for the CF group (P = 0.004). Differences in DGGE profiles were distinguished on the basis of a cluster analysis. Sequence analysis of excised DGGE bands consisted of 2.7 phylotypes, on average. After adjusting for the number of observed bands, we estimated that the S-ECC group exhibited 94.5 total phylotypes and that the CF group exhibited 113.4. These results suggest that the microbial diversity and complexity of the microbial biota in dental plaque are significantly less in S-ECC children than in CF children.

Bacterial Typing Techniques↗

Genetic profiling of enterohemorrhagic Escherichia coli strains in relation to clonality and clinical signs of infection.

Sixty-seven human strains of enterohemorrhagic Escherichia coli (EHEC) (from patients with more or less severe symptoms) were serogrouped and arranged according to pulsed-field gel electrophoresis (PFGE) patterns. We used PCR to investigate the strains according to known or putative virulence factors, and associations with disease were studied. All EHEC strains with the same PFGE pattern belonged to the same serogroup. On the contrary, two serogroups (O157 and O8) included strains with different PFGE patterns. We found several different combinations of chromosomal and plasmid-borne determinants, encoding the putative virulence factors, among the strains. As judged from clinical symptoms, there was no marked difference in pathogenicity among the strains and their combinations of virulence traits. All strains of O157 had the genes coding for verocytotoxin (VT) 2, intimin (eaeA), E. coli hemolysin (E-hly), and secreted serine protease (espP). Among EHEC non-O157 strains, the genes coding for VT1 and VT2 were equally dispersed. EaeA positivity was just as common among VT1- as VT2-positive strains. Among the plasmid-borne determinants, E-hly and espP were the most common and E-hly might be a pathogenicity marker among EHEC non-O157 strains. The conclusion is that PFGE is a very useful tool in epidemiological studies. The EHEC plasmids are heterogeneous in their gene composition, with the four plasmid-borne determinants found in many combinations. There was no reliable correlation between chromosomal and plasmid-borne virulence factors and human disease.

Adolescent↗

Identification of molecular markers specific for pancreatic neuroendocrine tumors by genetic profiling of core biopsies.

BACKGROUND: There is a paucity of known molecular markers that distinguish pancreatic neuroendocrine tumors from other pancreatic tumor types. We hypothesized that novel markers for pancreatic neuroendocrine tumors could be identified with molecular fingerprinting of pooled RNA samples from core biopsies. METHODS: Total RNA was harvested from nine core biopsies of normal pancreas, pancreatitis, pancreatic adenocarcinoma, pancreatic adenocarcinoma metastases, and pancreatic neuroendocrine tumors. RNA from each group of samples was pooled and hybridized to an oligonucleotide-based microarray. Four genes (ANG2, NPDC1, ELOVL4, and CALCR) were selected for further investigation by reverse transcriptase polymerase chain reaction from the top 20 highest expressed genes, on the basis of potential as novel markers. RESULTS: Neuroendocrine tumors were most unique from normal pancreas. Pancreatitis, pancreatic adenocarcinoma, and metastases are more closely related to each other and to normal pancreas. ANG2 was overexpressed in 89% of neuroendocrine tumors, compared with 22% of normal pancreas, making it the best potential molecular marker or therapeutic target of the four genes selected for analysis. CONCLUSION: We have identified a specific set of molecular markers for pancreatic neuroendocrine tumors distinct from pancreatitis and pancreatic adenocarcinoma. These novel markers may prove useful as molecular markers or therapeutic targets unique to pancreatic neuroendocrine tumors.

Adenocarcinoma↗