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At least 127 records · Page 7Linked to original sources

PubMed2005

Epigenetic changes in virus-associated human cancers.

Epigenetics of human cancer becomes an area of emerging research direction due to a growing understanding of specific epigenetic pathways and rapid development of detection technologies. Aberrant promoter hypermethylation is a prevalent phenonmena in human cancers. Tumor suppressor genes are often hypermethylated due to the increased activity or deregulation of DNMTs. Increasing evidence also reveals that viral genes are one of the key players in regulating DNA methylation. In this review, we will focus on hypermethylation and tumor suppressor gene silencing and the signal pathways that are involved, particularly in cancers closely associated with the hepatitis B virus, simian virus 40 (SV40), and Epstein-Barr virus. In addition, we will discuss current technologies for genome-wide detection of epigenetically regulated targets, which allow for systematic DNA hypermethylation analysis. The study of epigenetic changes should provide a global view of gene profile in cancer, and epigenetic markers could be used for early detection, prognosis, and therapy of cancer.

DNA Methylation↗

PubMed2006

A review of current and future molecular diagnostic tests for use in the microbiology laboratory.

Nucleic acid-based diagnostics gradually are replacing or complementing culture-based, biochemical, and immunological assays in routine microbiology laboratories. Similar to conventional tests, the first-generation deoxyribonucleic acid assays determined only a single analyte. Recent improvements in detection technologies have paved the way for the development of multiparameter assays using macroarrays or micro-arrays, while the introduction of closed-tube real-time polymerase chain reaction systems has resulted in the development of rapid microbial diagnostics with a reduced contamination risk. The use of these new molecular technologies is not restricted to detection and identification of microbial pathogens but also can be used for genotyping, allowing one to determine antibiotic resistance or to perform microbial fingerprinting.

Bacteria↗

PubMed2004

PCR-based detection of minority point mutations.

The need for detection of minority mutations (i.e., a few mutants within a high excess of wild-type alleles) arises frequently in the field of cancer and molecular genetics. Current mutation detection technologies are limited by several technical factors when it comes to the detection of minority point mutations, including generation of misincorporations by the DNA polymerase during PCR amplification. Primer ligation-mediated PCR methodologies for detection of mutations in an excess wild-type sequences are described, that can be applied for detection of both known and unknown minority point mutations. Furthermore, a new methodology is described, hairpin-PCR, which has the potential to completely eliminate PCR errors from amplified sequences, prior to minority mutation detection. Combination of these technologies can effectively tackle the problem of minority mutation detection, in order to pursue demanding applications such as identification of cancer cells at an early stage, detection of mutations in single cells, identification of minimal residual disease, or investigation of mechanisms of spontaneous mutagenesis.

DNA Mutational Analysis↗

PubMed2006

Defects can increase the melting temperature of DNA-nanoparticle assemblies.

DNA-gold nanoparticle assemblies have shown promise as an alternative technology to DNA microarrays for DNA detection and RNA profiling. Understanding the effect of DNA sequences on the melting temperature of the system is central to developing reliable detection technology. We studied the effects of DNA base-pairing defects, such as mismatches and deletions, on the melting temperature of DNA-nanoparticle assemblies. We found that, contrary to the general assumption that defects lower the melting temperature of DNA, some defects increase the melting temperature of DNA-linked nanoparticle assemblies. The effects of mismatches and deletions were found to depend on the specific base pair, the sequence, and the location of the defects. Our results demonstrate that the surface-bound DNA exhibit hybridization behavior different from that of free DNA. Such findings indicate that a detailed understanding of DNA-nanoparticle assembly phase behavior is required for quantitative interpretation of DNA-nanoparticle aggregation.

Base Pair Mismatch↗

PubMed2005

Operational effectiveness of suicide-bomber-detector schemes: a best-case analysis.

Standoff explosives-detection technologies allow, in principle, for the detection of pedestrian suicide bombers, although such sensors are not yet sufficiently affordable and reliable to justify widespread deployment. What if they were? Assuming the availability of cheap, perfectly sensitive and specific suicide-bomber-sensing devices, we analyze the operational effectiveness of sensor-based detector schemes in reducing casualties from random suicide-bombing attacks. We model the number of casualties resulting from pedestrian suicide bombings absent intervention, the reduction in casualties from alternative interventions, given timely detection of a suicide-bombing attack, and the probability of timely detection under best-case assumptions governing the performance of suicide-bomber-detector schemes in two different urban settings. Even under such optimistic assumptions, we find that the widespread deployment of suicide-bomber detectors will not reliably result in meaningful casualty reductions. Relaxing the best-case assumptions only makes matters worse. Investment in intelligence-gathering to prevent suicide bombers before they attack seems a wiser strategy than relying on sensor-based suicide-bomber-detector schemes.

Explosions↗

PubMed2002

[The developing trend of the clinical laboratory].

The clinical laboratory technology has gradually changed the traditional detection methods. The new detection technology provides a more rapid and more accurate way for the disease diagnosis. The designs of the clinical laboratory equipments pay more attention to human factors, low cost and benefit for environment protection.

Clinical Laboratory Information Systems↗

PubMed1999

Fast-in situ hybridization and immunoenzymatic color pigment detection of mouse bone marrow micronucleus.

The development of a whole mouse genomic DNA probe coupled to color pigment painting detection methodology can accurately verify mouse micronuclei induced by chemicals or drugs leading to a lower probability of potential artifacts. Using color pigment painting detection of probes in conjunction with Wright's Giemsa counterstain instead of the current fluorescence detection technology ensures low cost, high resolution permanent documentation of slides for a particular test compound. The permanent color pigment-detected micronuclei and adjoining counterstain allows slides to be stored for future analysis without enhancing the signal or adding antifading agents that are associated with fluorescence detection. Combining innovative technology such as fast-in situ hybridization of DNA probes with immunoenzymatic color pigment detection provides rapid verification of true micronuclei (DNA containing) within 2-3 hr.

Animals↗

PubMed2004

Feasibility study for a microchip-based approach for noninvasive prenatal diagnosis of genetic diseases.

Fetal DNA in maternal plasma may represent a source of genetic material for prenatal noninvasive diagnosis of genetic diseases. We evaluated a cohort of physiological pregnancies to determine if fetal DNA can be retrieved at any gestational week in sufficient quantity to be analyzed with advanced mutation detection technologies. We performed fetal DNA quantification by real-time polymerase chain reaction (PCR) on the SRY gene in 356 women sampled from 6 to 40 gestational weeks. Fetal DNA was retrieved at any week. All female fetuses were correctly identified. In 5 of 188 (2.6%) male-bearing pregnancies, no amplification was obtained. For noninvasive testing, complete clearance of fetal DNA after delivery is mandatory. Long-term persistence was not detected in women with previous sons or abortions. These findings confirm that maternal plasma may represent the optimal source of fetal genetic material. For noninvasive diagnosis of genetic diseases, we evaluated microchip technology. The detection limit for a minority allele determined by diluting a mutated DNA into a wild-type plasma sample was 5 genome equivalents, indicating that the test might be applied to the identification of paternally inherited fetal alleles in maternal plasma. The addition of peptide nucleic acids (PNAs) to either the PCR reaction or the chip hybridization mixture allowed approximately 50% inhibition of wild-type allele signals.

Adult↗

PubMed2004

Approaches for analyzing human mutations and nucleotide sequence variation: a report from the Seventh International Mutation Detection meeting, 2003.

The Seventh International Symposium on Mutations in the Human Genome, Mutation Detection 2003, was held during 2-6 July 2003 in Palm Cove near Cairns, Australia. The meeting was organized under the auspices of the Human Genome Organisation (HUGO) as a satellite meeting of the International World Congress of Genetics, held in Melbourne the following week. Meeting participants reported on advances in mutation detection technologies, including advances in high-throughput detection systems for SNP genotyping applicable to the international haplotype mapping project (HapMap); and bioinformatics tools, including databases for handling and processing growing amounts of genome variation data. This meeting report summarizes the presentations and cites related articles from the special issue of Human Mutation (Volume 23#5, May 2004; available online at www.wiley.com/humanmutation).

Base Sequence↗

PubMed1998

Comparison of gel technology and red cell affinity column technology in antibody detection.

Both column (gel) agglutination technology and red cell affinity column technology (ReACT) have been approved by the Food and Drug Administration for antibody detection and identification. Parallel studies using these two methods were performed on 100 samples to evaluate their sensitivity, advantages, and disadvantages. Sixteen significant antibodies, anti-D(2), -C(1), -E(1), -c(1), -C,D(1), -K(4), -S(1), -Fya(3), -Jka(1), and -Jkb(1), were found during the study. MTS-Gel detected one anti-D due to Rh immune globulin but missed one anti-Jka. ReACT missed one anti-D and one anti-Jkb. MTS-Gel detected one anti-I and one anti-H whereas ReACT detected two anti- H but not anti-I. No false positive reactions were found by either method. Sensitivity based on this study for MTS-Gel is 93.3% and ReACT is 86.7%. Advantages for MTS-Gel included the small volume needed for testing, and the reaction was stable for 48 hours; for ReACT, there was less spin time and no special pipette was needed. Disadvantages for MTS-Gel included the need for a special pipette and manual preparation of 0.8% RBC suspensions, and the disadvantages for ReACT included the small column for reaction reading and the reaction was stable for only 24 hours.

Journal Article↗

PubMed2001

Resonance light scattering particles as ultrasensitive labels for detection of analytes in a wide range of applications.

We have developed a new detection technology that uses resonance light scattering (RLS) particles as labels for analyte detection in a wide range of formats including immuno and DNA probe type of assays in solution, solid phase, cells, and tissues. When a suspension of nano sized gold or silver particles is illuminated with a fine beam of white light, the scattered light has a clear (not cloudy) color that depends on composition and particle size. This scattered light can be used as the signal for ultrasensitive analyte detection. The advantages of gold particles as detection labels are that (a) their light producing power is equivalent to more than 500,000 fluorescein molecules, (b) they can be detected at concentrations as low as 10(-15) M in suspension by eye and a simple illuminator, (c) they do not photobleach, (d) individual particles can be seen in a simple student microscope with dark field illumination, (e) color of scattered light can be changed by changing particle size or composition for multicolor multiplexing, and (f) they can be conjugated with antibodies, DNA probes, ligands, and protein receptors for specific analyte detection. These advantages allow for ultra-sensitive analyte detection with easiness of use and simple and relatively inexpensive instrumentation. We have shown that our RLS technology can indeed be used for ultra-sensitive detection in a wide range of applications including immuno and DNA probe assays in solution and solid phases, detection of cell surface components and in situ hybridization in cells and tissues. Most of the assay formats described in this article can be adapted for drug fast throughput screening.

Animals↗

PubMed2000

Rapid analysis of covalently and non-covalently fluorophore-labeled proteins using ultra-thin-layer sodium dodecylsulfate gel electrophoresis.

Gel electrophoresis is one of the most frequently used tools for the separation of complex biopolymer mixtures. In recent years, there has been considerable activity in the separation and characterization of protein molecules by sodium dodecylsulfate (SDS) gel electrophoresis with particular interest in using this technique to separate on the basis of size and to estimate molecular mass and protein purity. Although the method is informative, it is cumbersome, time consuming and lacks automation. In this paper we report an automated, high-performance SDS gel electrophoresis system that is based on electric-field-mediated separation of SDS-protein complexes using an ultra-thin-layer platform. The integrated fiber optic bundle-based scanning laser-induced fluorescence detection technology readily provided high sensitivity, real-time detection of the migrating solute molecules. Rapid separations of covalently and non-covalently labeled proteins were demonstrated in the molecular mass range 14,000 to 205,000 in less than 9 and 16 min, respectively. Excellent quantitation and lane-to-lane migration time reproducibility were found for all the solute components using the multilane separation platform. The limit of detection was found to be 1.5-3 ng/band for both labeling methods, with excellent linearity over a six times serial double-dilution range. Molecular mass calibration plots were compared for both covalently and non-covalently labeled proteins. A linear relationship was found between the molecular mass and electrophoretic mobility in the case of covalently labeled samples, while a non-linear relationship was revealed for the non-covalently labeled samples.

Calibration↗

PubMed2003

High throughput screening technologies for direct cyclic AMP measurement.

A study comparing five different cAMP detection technologies in terms of sensitivity, robustness, and feasibility for HTS is presented. In this report, the following methods are described: a nonhomogeneous DELFIA, and the homogeneous methods based on time-resolved fluorescence (HTRF), luminescent singlet oxygen channeling or ALPHAScreen, FP, and high-affinity enzyme complementation. DELFIA had the highest sensitivity, whereas ALPHAScreen and HTRF shared several advantages, including high sensitivity, broad dynamic range, and minimal reagent addition steps. For G(s)-coupled antagonist screens, we found HTRF and ALPHAScreen the more sensitive and HTS-compatible techniques.

Animals↗

PubMedDate not supplied

Sonographic findings in cases of missed gallstones.

UNLABELLED: PURPOSE. We retrospectively evaluated sonographic findings in 946 cases of gallstones to determine whether the false-negative rate for gallstone detection by sonography has decreased as a result of technologic advances over the past 15 years. METHODS: We reviewed preoperative sonographic reports, operative notes, and pathologic reports for 614 women and 332 men (ages 22-78 years) seen over a 2.5-year period and compared sonographic findings with surgical pathologic findings after cholecystectomy. Sonograms for patients whose gallstones were missed on sonography were reviewed by 3 board-certified radiologists. RESULTS: Preoperative sonography of the gallbladder accurately predicted the presence of gallstones in 934 cases (98.7%). Gallstones were not identified by sonography in the remaining 12 cases. In those cases, sonography revealed polyps in 5, sludge in 5, sludge plus a polyp in 1, and neither stones nor polyps in 1. Thus, the false-negative rate was 1.3%. CONCLUSIONS: Despite improvements in sonographic technology, detection of small gallstones remains difficult in some cases. Adherent gallstones can mimic gallbladder polyps. Our false-negative rate for detection of gallstones was no different from that in earlier studies.

Adult↗

PubMed2004

Brain stimulation as a therapy for epilepsy.

The failure of current antiepileptic therapies to adequately treat a significant number of epileptic patients highlights the need for the development of new treatments for the disorder. A new strategy that is currently being developed is to deliver electrical stimulation directly to the brain to decrease or prevent seizure activity. Clinical evidence that electrical stimulation could interfere with seizure activity was initially reported in the 1930's. However, many of these early studies consisted of case reports or were poorly controlled. In addition, there were a number of studies that failed to observe any beneficial effect of brain stimulation on seizures. More recently, deep brain stimulation has been used successfully to treat patients with movement disorders and vagus nerve stimulation has been shown to effectively decrease seizure activity in a select population of epilepsy patients. These advances have led to a reexamination of the potential therapeutic benefits of deep brain stimulation for the treatment of epilepsy. There is now experimental and clinical evidence that direct electrical stimulation of the brain can prevent or decrease seizure activity. However, several fundamental questions remain to be resolved. They include where in the brain the stimulus should be delivered and what type of stimulation would be most effective. One goal of this research is to combine the beneficial aspects of electrical stimulation with seizure detection technology in an implantable responsive stimulator. The device will detect the onset of a seizure and deliver an electrical stimulus that will safely block seizure activity without interfering with normal brain function.

Animals↗

PubMed2005

Cancer epigenetics.

The field of cancer epigenetics is evolving rapidly on several fronts. Advances in our understanding of chromatin structure, histone modification, transcriptional activity and DNA methylation have resulted in an increasingly integrated view of epigenetics. In response to these insights, epigenetic therapy is expanding to include combinations of histone deacetylase inhibitors and DNA methyltransferase inhibitors. Zebularine, an orally administerable DNA methyltransferase inhibitor, has been a very promising recent addition to our arsenal of potentially useful drugs for epigenetic therapy. Aberrant DNA methylation patterns provide three powerful diagnostic applications as classification markers, sensitive detection markers, and risk assessment markers. Classification studies continue to increase in marker complexity, now incorporating microarrays, high-throughput bisulfite genomic sequencing and mass spectrometry, as the field moves to human epigenome projects. Sensitive detection technology has expanded from primarily blood-based cancer detection to include applications on a wide diversity of sample sources and is now also making inroads as a molecular risk assessment tool.

Antineoplastic Agents↗

PubMed2001

Enabling large-scale pharmacogenetic studies by high-throughput mutation detection and genotyping technologies.

BACKGROUND: Pharmacogenetics is a scientific discipline that examines the genetic basis for individual variations in response to therapeutics. Pharmacogenetics promises to develop individualized medicines tailored to patients' genotypes. However, identifying and genotyping a vast number of genetic polymorphisms in large populations also pose a great challenge. APPROACH: This article reviews the recent technology development in mutation detection and genotyping with a focus on genotyping of single nucleotide polymorphisms (SNPs). CONTENT: Novel mutations/polymorphisms are commonly identified by conformation-based mutation screening and direct high-throughput heterozygote sequencing. With a large amount of public sequence information available, in silico SNP mapping has also emerged as a cost-efficient way for new polymorphism identification. Gel electrophoresis-based genotyping methods for known polymorphisms include PCR coupled with restriction fragment length polymorphism analysis, multiplex PCR, oligonucleotide ligation assay, and minisequencing. Fluorescent dye-based genotyping technologies are emerging as high-throughput genotyping platforms, including oligonucleotide ligation assay, pyrosequencing, single-base extension with fluorescence detection, homogeneous solution hybridization such as TaqMan, and molecular beacon genotyping. Rolling circle amplification and Invader assays are able to genotype directly from genomic DNA without PCR amplification. DNA chip-based microarray and mass spectrometry genotyping technologies are the latest development in the genotyping arena. SUMMARY: Large-scale genotyping is crucial to the identification of the genetic make-ups that underlie the onset of diseases and individual variations in drug responses. Enabling technologies to identify genetic polymorphisms rapidly, accurately, and cost effectively will dramatically impact future drug and development processes.

Genotype↗

PubMed2002

A GCMSD/ECD method for the simultaneous determination of toxaphene and toxaphene congeners.

The methodology presented combines mass selective detection technology for routine automated total toxaphene determinations with electron capture detection confirmation of congener results. Total toxaphene values were calculated using a custom developed series of data analysis macroinstructions (macros) that eliminate potential interferences and collate peak areas. These macros create multi-level calibration tables with results automatically corrected for surrogate and performance standards. It is possible to produce congener data that provides results from both detectors in one report from a single injection.

Gas Chromatography-Mass Spectrometry↗