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At least 235 records · Page 13Linked to original sources

PubMed2005

Real-time nucleic acid sequence-based amplification is more convenient than real-time PCR for quantification of Plasmodium falciparum.

Determination of the number of malaria parasites by routine or even expert microscopy is not always sufficiently sensitive for detailed quantitative studies on the population dynamics of Plasmodium falciparum, such as intervention or vaccine trials. To circumvent this problem, two more sensitive assays, real-time quantitative nucleic acid sequence-based amplification (QT-NASBA) and real-time quantitative PCR (QT-PCR) were compared for quantification of P. falciparum parasites. QT-NASBA was adapted to molecular beacon real-time detection technology, which enables a reduction of the time of analysis and of contamination risk while retaining the specificity and sensitivity of the original assay. Both QT-NASBA and QT-PCR have a sensitivity of 20 parasites/ml of blood, but QT-PCR requires a complicated DNA extraction procedure and the use of 500 microl of venous blood to achieve this sensitivity, compared to 50 microl of finger prick blood for real-time QT-NASBA. Both techniques show a significant correlation to microscopic parasite counts, and the quantification results of the two real-time assays are significantly correlated for in vitro as well as in vivo samples. However, in comparison to real-time QT-PCR, the results of real-time QT-NASBA can be obtained 12 h earlier, with relatively easy RNA extraction and use of finger prick blood samples. The prospective development of multiplex QT-NASBA for detection of various P. falciparum developmental stages increases the value of QT-NASBA for malaria studies. Therefore, for studies requiring sensitive and accurate detection of P. falciparum parasites in large numbers of samples, the use of real-time QT-NASBA is preferred over that of real-time QT-PCR.

Animals↗

PubMed2003

Does frequency doubling technology perimetry reliably detect neurological visual field defects?

AIM: To determine the ability of frequency doubling technology (FDT) perimetry to detect visual field defects of neurological origin. METHODS: A total of 15 eyes of nine patients who all had complete hemianopias or quadrantanopias underwent the FDT 20-5 screening mode test and Humphrey 24-2 SITA Fast visual field test (HFA). The FDT results were scored according to the number of abnormal test locations (out of a maximum of 4) in each affected quadrant. FDT locations showing a defect of P< 2% were considered abnormal. RESULTS: Of the 15 eyes, six showed complete superior quadrantanopic and nine complete hemianopic field defects on HFA. Of 96 FDT test locations in these quadrants or hemifields only 38 were abnormal on FDT testing (40%). For the quadrantanopic field defects, five out of 24 locations were abnormal (21%). For the hemianopic field defects, 33 out of 72 locations were abnormal (49%). In three eyes (two with quadrantanopias and one with complete hemianopia), FDT perimetry failed to demonstrate any corresponding abnormality. CONCLUSIONS: The FDT screening test can fail to demonstrate complete hemianopic and quadrantanopic field defects. Users should be aware of this deficiency when using FDT to screen for field defects.

Adolescent↗

PubMed1992

Assessment of geometric treatment accuracy using time-lapse display of electronic portal images.

During the past two years, several electronic portal imaging systems have been introduced to the market by therapy accelerator manufacturers and other vendors. While these systems differ substantially in their detection technology, they are all capable of displaying portal images on a video screen in near real-time, and of creating multiple static (or "movie") images during each treatment. Major questions confront the users of such systems as to the best utilization of this wealth of information, and to its value in comparison to traditional weekly portal film methods. Using an "in-house" video based system, a new technique was established to aid in the assessment of on-line images so that immediate "go/no-go" decisions can be made by the therapy technologist. A video "movie-loop" is displayed which consists of the static image of the initial (approved) set-up, and the current treatment image. Multiple images of successive treatments can also be viewed in this "time-lapse" display mode to provide a quick visual means for review of an entire course of therapy. The on-line imaging system hardware is composed of a combination copper-plate/fluorescent-screen detector, a front surface mirror angled at 45 degrees to remove the camera from the direct radiation beam, and a high sensitivity SIT video camera. This assembly is attached to a rigid base and mounted directly to the isocentric gantry. The geometry is fixed to within +/- 1 mm and assures the precise day-to-day reproducibility which is necessary for the success of the time-lapse display technique. Experience with this technique shows it to enhance the user's ability to notice small changes in patient's position with respect to the radiation field. Radiation treatment sites reviewed using this procedure were Hodgkin's (mantle), Lung, Brain and extremities. Shifts in patient position on the order of several millimeters were readily detectable, as will be demonstrated in this paper. Somewhat surprisingly, grosser movements (greater than 1 cm) were also noted despite overall technical excellence as assessed by weekly portal filming. The eye senses day-to-day movement with greater ease when the fields are seen in time-lapse display than when compared as discrete portal images. Ultimately, persistent movement appreciated on the time-lapse display can suggest the need for a change in patient set-up or immobilization technique.

Humans↗

PubMed2002

Advances in sol-gel based columns for capillary electrochromatography: sol-gel open-tubular columns.

The development of sol-gel open-tubular column technology in capillary electrochromatography (CEC) is reviewed. Sol-gel column technology offers a versatile means of creating organic-inorganic hybrid stationary phases. Sol-gel column technology provides a general approach to column fabrication for microseparation techniques including CEC, and is amenable to both open-tubular and monolithic columns. Direct chemical bonding of the stationary phase to the capillary inner walls provides enhanced thermal and solvent stability to sol-gel columns. Sol-gel stationary phases inherently possess higher surface area, and thus provide an effective one-step alternative to conventional open-tubular column technology. Sol-gel column technology is applicable to both silica-based and transition metal oxide-based hybrid stationary phases, and thus, provides a great opportunity to utilize advanced material properties of a wide range of nontraditional stationary phases to achieve enhanced selectivity in analytical microseparations. A wide variety of stationary phase ligands can be chemically immobilized on the capillary inner surface using a single-step sol-gel procedure. Sol-gel chemistry can be applied to design stationary phases with desired chromatographic characteristics, including the possibility of creating columns with either a positive or a negative charge on the stationary phase surface. This provides a new tool to control electroosmotic flow (EOF) in the column. Column efficiencies on the order of half a million theoretical plates per meter have been reported for sol-gel open-tubular CEC columns. The selectivity of sol-gel stationary phases can be easily fine-tuned by adjusting the composition of the coating sol solution. Open-tubular columns have significant advantages over their packed counterparts because of the simplicity in column making and hassle-free fritless operation. Open-tubular CEC columns possess low sample capacity and low detection sensitivity. Full utilization of the analytical potential of sol-gel open-tubular columns will require a concomitant development in the area of high-sensitivity detection technology.

Chromatography↗

PubMed2006

Effect of pioglitazone compared with glimepiride on carotid intima-media thickness in type 2 diabetes: a randomized trial.

CONTEXT: Carotid artery intima-media thickness (CIMT) is a marker of coronary atherosclerosis and independently predicts cardiovascular events, which are increased in type 2 diabetes mellitus (DM). While studies of relatively short duration have suggested that thiazolidinediones such as pioglitazone might reduce progression of CIMT in persons with diabetes, the results of longer studies have been less clear. OBJECTIVE: To evaluate the effect of pioglitazone vs glimepiride on changes in CIMT of the common carotid artery in patients with type 2 DM. DESIGN, SETTING, AND PARTICIPANTS: Randomized, double-blind, comparator-controlled, multicenter trial in patients with type 2 DM conducted at 28 clinical sites in the multiracial/ethnic Chicago metropolitan area between October 2003 and May 2006. The treatment period was 72 weeks (1-week follow-up). CIMT images were captured by a single ultrasonographer at 1 center and read by a single treatment-blinded reader using automated edge-detection technology. Participants were 462 adults (mean age, 60 [SD, 8.1] years; mean body mass index, 32 [SD, 5.1]) with type 2 DM (mean duration, 7.7 [SD, 7.2] years; mean glycosylated hemoglobin [HbA1c] value, 7.4% [SD, 1.0%]), either newly diagnosed or currently treated with diet and exercise, sulfonylurea, metformin, insulin, or a combination thereof. INTERVENTIONS: Pioglitazone hydrochloride (15-45 mg/d) or glimepiride (1-4 mg/d) as an active comparator. MAIN OUTCOME MEASURE: Absolute change from baseline to final visit in mean posterior-wall CIMT of the left and right common carotid arteries. RESULTS: Mean change in CIMT was less with pioglitazone vs glimepiride at all time points (weeks 24, 48, 72). At week 72, the primary end point of progression of mean CIMT was less with pioglitazone vs glimepiride (-0.001 mm vs +0.012 mm, respectively; difference, -0.013 mm; 95% confidence interval, -0.024 to -0.002; P = .02). Pioglitazone also slowed progression of maximum CIMT compared with glimepiride (0.002 mm vs 0.026 mm, respectively, at 72 weeks; difference, -0.024 mm; 95% confidence interval, -0.042 to -0.006; P = .008). The beneficial effect of pioglitazone on mean CIMT was similar across prespecified subgroups based on age, sex, systolic blood pressure, duration of DM, body mass index, HbA(1c) value, and statin use. CONCLUSION: Over an 18-month treatment period in patients with type 2 DM, pioglitazone slowed progression of CIMT compared with glimepiride. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00225264

Adult↗

PubMedDate not supplied

Applications of biochemiluminescence to HACCP.

The hazard analysis critical control point) (HACCP) system is set up with the aim of ensuring the harmlessness of food along the process chain, from the producer to the ultimate consumer. To set up this system, it is necessary to perform an analysis to identify the dangers and the critical points of the process in real time. Living organisms are detected on the principle of measurement of cellular energy in the form of adenosine triphosphate (ATP), which is produced by all living cells and of particularly by microorganisms. The principle of the bioluminescence of firefly luciferase is applied, whereby a reduced form of luciferin, together with a molecule of oxygen and ATP in the presence of the enzyme luciferase, produces a reaction in which oxyluciferine is released, together with AMP. This is accompanied by a simultaneous release of photons, which are then quantified. The emission spectra recorded with the firefly luciferin/luciferase system is obtained with absolute sensitivity. The method of ATP assays here proposed is adapted for measuring the total content of different adenylates in the cell, i.e. the adenylate pool. ATP concentration is then measured through bioluminescence, i.e. the light is measured by a photomultiplier tube detector and the signal is converted to relative light units (RLU). Thus, RLU have a relationship with the amount of ATP present in the sample, which is not the case with traditional methods. Adequate levels of sensitivity are calculated with appropriate controls and the readings are translated into a statistical designation of positive or negative result. There are numerous illustrations of HACCP applications using biochemiluminescence (BCL) techniques as detection technology in food industry production lines and in control of critical points in real time in industrial applications.

Adenosine Triphosphate↗

PubMed1994

Mutation detection by denaturing gradient gel electrophoresis (DGGE).

The molecular analysis of genetic diseases relies on several technical approaches which allow genetic and physical mapping, characterization of the gene structure, expression studies, and identification of disease-causing mutations. Denaturing gradient gel electrophoresis (DGGE) allows the rapid screening for single base changes in enzymatically amplified DNA. The technique is based on the migration of double-stranded DNA molecules through polyacrylamide gels containing linearly increasing concentrations of a denaturing agent. In this review DGGE and the several modifications of the original protocol are presented. Moreover, its applications in human molecular genetics are summarized together with a preliminary comparison with other mutation detection technologies such as chemical cleavage, RNase protection, and single-strand conformation polymorphism.

Base Sequence↗

PubMed1974

Diffusion of anti-tumor drugs through membranes from hydrophilic methacrylate gels.

Permeation parameters of four anti-tumor drugs across membranes prepared from hydrophilic methacrylate gels were measured and compared with the permeation of NaCl. It was found that by increasing the ratio of butyl methacrylate (BMA) to hydroxyethyl methacrylate (HEMA), the rate of diffusion can be lowered to practically zero at 20% BMA. However, this decrease is different with various drugs due to the interaction of the drug with the gel. Differences by a factor of two were found in our set of drugs. Therefore, each new drug should be tested in this way. In addition a routine testing of dialysing devices by an NaCl solution is suggested as a method for detecting technological imperfections and calibrating the deviations from standard parameters. A chemical modification of the membrane is recommended as the best way for controlling the permeation rate.

Acrylates↗

PubMed2006

Unique selective detectors for gas chromatography: nitrogen and sulfur chemiluminescence detectors.

Many of present day's complex analyses and challenging analytical tasks demand highly selective detection techniques for GC. Universal nitrogen/sulfur chemiluminescence detection is one of the most powerful analytical tools for gas chromatographic analysis. Its strength stems from the unique and beneficial characteristics of high selectivity, sensitivity, and equimolarity. The nitrogen/sulfur chemiluminescence detection technology has provided analytical solutions unsurpassed by any other techniques to a broad range of applications in petroleum characterization, food/beverage flavor analysis, and environmental monitoring. This paper presents a general review of this unique technology, including a brief description of operating principles, an overview of detector performance, practical discussions on instrument operation, and a sizable list of applications.

Chromatography, Gas↗

PubMed2006

Mass spectrometry-based proteomics for the detection of plant pathogens.

Plant diseases caused by fungi, oomycetes, viruses, and bacteria are devastating both to the economy and to the food supply of a nation. Therefore, the development of new, rapid methods to identify these pathogens is a highly important area of research that is of international concern. MS-based proteomics has become a powerful and increasingly popular approach to not only identify these pathogens, but also to better understand their biology. However, there is a distinction between identifying a pathogen protein and identifying a pathogen based upon the detection of one of its proteins and this must be considered before the general application of MS for plant pathogen detection is made. There has been a recent push in the proteomics community to make data from large-scale proteomics experiments publicly available in the form of a centralized repository. Such a resource could enable the use of MS as a universal plant pathogen detection technology.

Bacterial Proteins↗

PubMed1995

Environmental tobacco smoke and coronary heart syndromes: absence of an association.

Concerns about possible cardiovascular and especially coronary effects of environmental tobacco smoke (ETS) derive from the reported effects of active smoking. Despite similarities, however, ETS has composition and physical characteristics different from the mainstream smoke (MS) that active smokers inhale and appears relatively more chemically inert and less biologically active. ETS doses to nonsmokers are small and often below the sensitivity of detection technologies. They are several orders of magnitude less than MS doses in active smokers. Numerous epidemiologic studies report that the active smoking of less than 10 cigarettes/day is not associated with measurable risk of coronary heart disease (CHD). Thus, even assuming that ETS and MS have equivalent biologic activities, conceivable ETS doses to nonsmokers are far below apparent no-effect thresholds for active smoking. Hence, it is no surprise that epidemiologic reports are inconclusive about a possible association of ETS exposure and CHD, some suggesting a slight elevation, others a reduction of risk. Often, the elevations reported are higher than the CHD risk values associated with active smoking. Such equivocations likely result from the presence of contrasting protective or aggravating confounders, of which more than 200 have been reported in the literature--confounders that were not and could not be adequately controlled by any epidemiologic study. By scientific standards, the weight of evidence continues to falsify the hypothesis that ETS exposure might be a CHD risk factor.

Animals↗

PubMed2007

Metabolite profiling in blood plasma.

Metabolite profiling has been established as a multiparallel strategy for relative quantification of a mixture of compounds or compound classes using chromatography and universal detection technologies (gas chromatography-mass spectrometry [GC-MS], liquid chromatography-MS). Despite its origins dating back to the late 1960s, it was only in the 1980s that its use was acknowledged to diagnose metabolic disorders in men, especially for rapid screening of inborn errors. Even faster electrospray ionization-MS/MS screening methods replaced longish chromatographic methods, and method development had stopped despite its potential use for other, less imminent diseases such as likelihood assessments of type II diabetes mellitus or cardiovascular risk factor evaluation. In addition to its diagnostic use, profiling blood samples can be employed to investigate specific biochemical responses. The broader scope of analysis outweighs the disadvantages by taking compromises in method development and the reduced accuracy for specific metabolites. This chapter exemplifies the strategies in metabolite profiling by GC-MS. It gives experimental details on basic steps like blood plasma withdrawal, storage, protein precipitation, extraction, concentration, derivatization, data acquisition, raw data processing, and result data tranformation. A major difference to profiling plant tissues is that no fractionation step is utilized, enabling the analysis of primary metabolites like sugars and amino acids concomitant with lipids such as sterols and free fatty acids.

Amino Acids↗

PubMed2002

The development of multiplex simple sequence repeat (SSR) markers to complement distinctness, uniformity and stability testing of rape (Brassica napus L.) varieties.

To assess the potential of multiplex SSR markers for testing distinctness, uniformity and stability of rape (Brassica napus L.) varieties, we developed three multiplex SSR sets composed of five markers each. These were used to measure the extent of diversity within and between a set of ten varieties using a fluorescence-based semi-automated detection technology. Also, we evaluated the significance of any correlation between SSRs, pedigree and five of the morphological characters currently used for statutory distinctness, uniformity and stability testing of rape varieties. An assignment test was allowed to identify 99% of the plants examined, with the correct variety based on the analysis of 48 individual plants for each variety. Principal coordinate analysis confirmed that a high degree of separation between varieties could be achieved. Varieties were separated in three groups corresponding to winter, spring and forage types. These results suggested that it should be possible to select a set of markers for obtaining a suitable separation. Diversity within varieties varied considerably, according to the variety and the locus examined. No significant correlation was found between SSR and morphological data. However, genetic distances measured by SSRs were correlated to pedigree. These results suggested that SSRs could be used for pre-screening or grouping of existing and candidate varieties, allowing the number of varieties that need to be grown for comparison to be reduced. Multiplex SSR sets gave high-throughput reproducible results, thus reducing the costs of SSR assessment. Multiplex SSR sets are a promising way forward for complementing the current variety testing system in B. napus.

Brassica napus↗

PubMed2005

Gene expression analysis of Escherichia coli grown in miniaturized bioreactor platforms for high-throughput analysis of growth and genomic data.

Combining high-throughput growth physiology and global gene expression data analysis is of significant value for integrating metabolism and genomics. We compared global gene expression using 500 ng of total RNA from Escherichia coli cultures grown in rich or defined minimal media in a miniaturized 50-microl bioreactor. The microbioreactor was fabricated out of poly(dimethylsiloxane) (PDMS) and glass and equipped to provide on-line, optical measurements. cDNA labeling for microarray hybridizations was performed with the GeniconRLS system. From these experiments, we found that the expression of 232 genes increased significantly in cells grown in minimum medium, including genes involved in amino acid biosynthesis and central metabolism. The expression of 275 genes was significantly elevated in cells grown in rich medium, including genes involved in the translational and motility apparatuses. In general, these changes in gene expression levels were similar to those observed in 1,000-fold larger cultures. The increasing rate at which complete genomic sequences of microorganisms are becoming available offers an unprecedented opportunity for investigating these organisms. Our results from microscale cultures using just 500 ng of total RNA indicate that high-throughput integration of growth physiology and genomics will be possible with novel biochemical platforms and improved detection technologies.

Bioreactors↗

PubMed2006

Imaging membrane potential in dendrites and axons of single neurons.

This review focuses on the use of imaging techniques to record electrical signaling in the fine processes of neurons such as dendrites and axons. Voltage imaging began with the use and development of externally applied voltage-sensitive dyes. With the introduction of internally applied dyes and advances in detection technology, it is now possible to record supra-threshold action potential responses, as well as sub-threshold synaptic potentials, in fine neuronal processes including dendritic spines. The development of genetically coded sensors, as well as variants of laser scanning microscopy such as second harmonic generation, offers promise for further advances in this field. Through the use and further development of these methods, optical imaging of membrane potential will continue to be a valuable tool for investigators wishing to explore the electrical events underlying single neuronal computation.

Action Potentials↗

PubMed2006

Cell cycle checkpoints: the role and evaluation for early diagnosis of senescence, cardiovascular, cancer, and neurodegenerative diseases.

Maintenance of genomic integrity is critical for prevention of a wide variety of adverse cellular effects including apoptosis, cellular senescence, and malignant cell transformation. Under stress conditions and even during an unperturbed cell cycle, checkpoint proteins play the key role in genome maintenance by and mediating cellular response to DNA damage, and represent an essential part of the "cellular stress response proteome". Intact checkpoint signal transduction cascades check the presence of genome damage, trigger cell cycle arrest, and forward the information to the protein core of cell cycle machinery, replication apparatus, repair, and/or apoptotic protein cores. Genetic checkpoint defects lead to syndromes that demonstrate chromosomal instability, increased sensitivity to genotoxic stress, tissue degeneration, developmental retardation, premature aging, and cancer predisposition that is most extensively studied for the ATM-checkpoint mutated in Ataxia telangiectasia. Tissue specific epigenetic control over the function of cell cycle checkpoints can be, further, misregulated by aberrant DNA methylation status. The consequent checkpoint dysregulation may result in tissue specific degenerative processes such as degeneration and calcification of heart aortic valves, diabetic cardiomyopathy, hyperhomocysteinemic cerebrovascular, peripheral vascular and coronary heart diseases, neurodegenerative disorders (Alzheimer and Parkinson diseases, amyotrophic lateral sclerosis, glaucoma), and accelerated aging frequently accompanied with cancer. This review focuses on the checkpoints shown to be crucial for unperturbed cell cycle regulation, dysregulation of which might be considered as a potential molecular marker for early diagnosis of and therapy efficiency in neurodegenerative, cardiovascular and cancer diseases. An application of the most potent detection technologies such as "Disease Proteomics and Transcriptomics" also considered here, allows a most specific selection of diagnostic markers.

Animals↗

PubMed2007

Molecular diagnosis of neurofibromatosis type 1: 2 years experience.

Our experience of providing an NF1 gene diagnostic mutation detection service as part of the U.K. Genetic Testing Network (UKGTN) is presented. A total of 169 unrelated individuals suspected of having neurofibromatosis type I (NF1) were referred for NF1 diagnostic testing over a 2 year period. Mutation analysis of the entire NF1 coding region and the flanking splice sites was carried out, and included the use of a combination of FISH, dHPLC and MLPA. Possible disease causing mutations were identified in 109 (64%) cases. These comprised 88 different sequence alterations, of which 57 were novel. Out of the 169 cases referred, there were 102 patients with reliable clinical data, of whom 78 satisfied the NIH diagnostic criteria for NF1. Within this better defined cohort of NF1 patients, NF1 mutations were identified in 61 individuals (78%), showing the importance of clinical selection on overall test sensitivity, and highlighting the problem of full clinical data collection in the audit of routine services. As mutation detection technologies advance, facilitating direct sequencing of all coding and flanking non-coding regions of the NF1 gene, the development of an even more cost-effective, quick and sensitive diagnostic test for future testing of NF1 is discussed.

Alternative Splicing↗

PubMed2006

Cultural and Immunological Detection Methods for Salmonella spp. in Animal Feeds - A Review.

Food-borne salmonellosis continues to be a major public health concern, and contamination with Salmonella spp. in pre-harvest animal production is considered a primary contributor to this problem. Animal feeds can easily become contaminated during primary production, feed mixing and processing as well as during feeding. Consequently, monitoring and surveillance of feeds and feed ingredients for Salmonella spp. contamination may be useful or necessary in the prevention and control of this organism. Cultural and immunological detection methods for salmonellae have been used or suggested as possible approaches for use in animal feeds. Cultural methods remain advantageous owing to their ability to detect viable bacterial cells, while immunological methods have the capability of detecting nonculturable bacterial cells. Advancements and improvements in both methodologies offer opportunities for eventual routine use of these detection technologies in animal feed assays.

Animal Feed↗