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PubMedDate not supplied

Rapid diagnosis of candidiasis and aspergillosis.

Published studies support the hypothesis that at least two antigens of Candida albicans and Candida tropicalis circulate in the bloodstream of patients with severe candidiasis. One antigen (probably mannan) is stable and the other (probably protein) is labile. The stabile antigen can rarely be detected without prior dissociation from antibody. Dissociation treatment destroys the labile antigen, leaving in doubt whether any is antibody bound. Dissociation steps have also been necessary for detection of Aspergillus fumigatus antigen in sera from patients with invasive aspergillosis. Concentrations of the stable antigens of both Candida and Aspergillus appear to be in the nanogram-per-milliliter range, generally lying at the limits of detection by conventional assays. Improvements in sensitivity and practicality are needed, but the tests are clearly promising.

Animals↗
PubMed2004

Advances in analytical technologies for environmental protection and public safety.

Due to the increased threats of chemical and biological agents of injury by terrorist organizations, a significant effort is underway to develop tools that can be used to detect and effectively combat chemical and biochemical toxins. In addition to the right mix of policies and training of medical personnel on how to recognize symptoms of biochemical warfare agents, the major success in combating terrorism still lies in the prevention, early detection and the efficient and timely response using reliable analytical technologies and powerful therapies for minimizing the effects in the event of an attack. The public and regulatory agencies expect reliable methodologies and devices for public security. Today's systems are too bulky or slow to meet the "detect-to-warn" needs for first responders such as soldiers and medical personnel. This paper presents the challenges in monitoring technologies for warfare agents and other toxins. It provides an overview of how advances in environmental analytical methodologies could be adapted to design reliable sensors for public safety and environmental surveillance. The paths to designing sensors that meet the needs of today's measurement challenges are analyzed using examples of novel sensors, autonomous cell-based toxicity monitoring, 'Lab-on-a-Chip' devices and conventional environmental analytical techniques. Finally, in order to ensure that the public and legal authorities are provided with quality data to make informed decisions, guidelines are provided for assessing data quality and quality assurance using the United States Environmental Protection Agency (US-EPA) methodologies.

Biosensing Techniques↗
PubMed1989

Fecal occult blood testing. Problems, pitfalls, and diagnostic concerns.

The diagnostic approach to the asymptomatic patient who has tested positive for fecal occult blood varies among clinicians. Colonoscopic evaluation is the procedure of choice in initiating the workup of patients 50 years of age and older. In younger patients, examination by sigmoidoscopy and barium enema using air for contrast (double contrast study) may be considered as an alternative to colonoscopy as the initial test. Evaluation of the upper gastrointestinal tract should be considered if a colonic source is not detected. The challenge in diagnostic test selection lies in choosing the most appropriate and cost-effective procedure for detecting disease, especially neoplastic lesions.

Barium Sulfate↗
PubMedDate not supplied

The likelihood of remaining normotensive following antihypertensive drug withdrawal.

OBJECTIVE: To determine the proportion and characteristics of mild hypertensives who remain normotensive after withdrawal from drug treatment. DESIGN: Longitudinal descriptive study. SETTING: A university family practice unit (FPU) and a large steel company (DOFASCO) in Hamilton, Ontario. PATIENTS: Participants were 107 of 125 (86%) eligible hypertensives at the two sites; 103 (96%) subjects completed the study. INTERVENTION: Subjects discontinued antihypertensive medication and were followed until blood pressure (BP) became elevated or for 12 months, whichever was shorter. MEASUREMENTS AND MAIN RESULTS: BPs were monitored according to a predefined schedule and before, during, and after mental and physical stress tests. Thirty-eight (37%, 95% confidence interval [CI] 27-46%) subjects remained normotensive at 12 months. Predictors of remaining normotensive included lower medicated standing diastolic blood pressure (DBP) (87.6 versus 91.8 mm Hg, 95% CI for the difference 2.2-6.2, p less than 0.001) and longer duration of normotension on drugs (12.6 months versus 8.7, 95% CI for the difference 0.9-6.9, p = 0.012). There was no significant relationship between maintenance of normotension and age, medication potency, duration of hypertension, weight, lying BP, change in heart rate, or BP during mental or physical stress tests; the power to detect a clinically important difference in lying DBP was 99% but for other variables was lower (21-75%). CONCLUSIONS: The probability of hypertensives' remaining normotensive for one year after drug withdrawal increases as the medicated standing DBP decreases and as the number of months of BP control while on medication increases. Studies with larger sample sizes are warranted to determine whether other variables may be significant predictors.

Adult↗
PubMed1994

petD mRNA maturation in Chlamydomonas reinhardtii chloroplasts: role of 5' endonucleolytic processing.

Complex processing of primary transcripts occurs during the expression of higher-plant chloroplast genes. In Chlamydomonas reinhardtii, most chloroplast genes appear to possess their own promoters, rather than being transcribed as part of multicistronic operons. By generating specific deletion mutants, we show that petD, which encodes subunit IV of the cytochrome b6/f complex, has an RNA processing site that is required for accumulation of monocistronic petD mRNA in petD promoter deletion mutants; in such mutants, transcription of petD originates from the upstream petA promoter. The 5' ends of transcripts initiated at the petD promoter are probably also generated by processing, since the 5' end of monocistronic petD mRNA is the same in wild-type strains as it is in the petD promoter mutants. The location and function of the processing site were further examined by inserting petD-uidA fusion genes into the chloroplast genome (uidA is an Escherichia coli gene that encodes beta-glucuronidase). When a promoterless petD-uidA fusion gene was inserted downstream of petA, a monocistronic uidA transcript accumulated, which was apparently initiated at the petA promoter and was processed at a site corresponding precisely to the petD mRNA 5' end. When a construct including only sequences downstream of +25 relative to the mature mRNA 5' end was inserted into the same site, a dicistronic petA-uidA transcript accumulated but no monocistronic uidA transcript could be detected, suggesting that a processing site lies at least partially within the region from -1 to +25. Beta-glucuronidase activity was not detected in transformants that accumulated only the dicistronic petA-uidA transcript, suggesting that the first 25 bp of the 5' untranslated region are required for translation initiation. One explanation for this translational defect is that Chlamydomonas chloroplasts cannot translate the second coding region of some dicistronic messages.

Animals↗
PubMed1998

How often does lateral spine DXA detect low bone mass in patients with both normal PA spine and hip?

The clinical utility of lateral bone mineral density (BMD) measurement for the diagnosis of osteoporosis remains controversial. Since both posterior-anterior (PA) spine and hip scans are universally performed, the true clinical utility of lateral dual-energy X-ray absorptiometry (DXA) should lie in its ability to detect low bone mass independent of both PA spine and hip. We examined lateral, PA and hip BMDs in 2134 referred Caucasian females aged 25-89 using the Hologic 2000. Compared only to PA scans, the additional percentages of women with very low BMD (T-score below -2.5 utilizing the National Health and Nutrition Examination Survey [NHANES] III normative database) on lateral were 7.3, 16.4, 28.2, 33.7, and 26.2% for age groups 25-49, 50-59, 60-69, 70-79, and 80-89, respectively. When the results from both PA and total hip measurements were combined, lower but still significant percentages were found: 5.4, 14.9, 24.4, 26.6, and 17.8% for age groups 25-49, 50-59, 60-69, 70-79, and 80-89, respectively. Utilizing the original Hologic normative database, the additional yield in women with a nonosteoporotic PA spine and femoral neck was quite low: 4.6, 8.5, 13.3, 10.0, and 2.5% for women age 25-49, 50-59, 60-69, 70-79, and 80-89, respectively. Thus, the lateral scans now add more additional patients into the very low BMD category. Whether the relationship to future fracture risk of low BMD and T-scores on lateral is similar to that of PA spine remains to be established.

Journal Article↗
PubMed1984

Collagen orientation in compact bone: I. A new method for the determination of the proportion of collagen parallel to the plane of compact bone sections.

Previous work has shown that different types of osteons that have different mechanical properties with regard to tension and compression can be identified and studied by polarized light microscopy. This study reports the development of an automated method for the analysis of that proportion of collagen in transverse sections of human femurs that lies parallel with the plane of section. The method is based upon the use of circularly polarized light to detect collagen with a major component lying in the plane of the section, correcting the measurement for bright collagen under these circumstances with a corresponding darkfield measurement to determine the area of bone within each field of the section analyzed. The method has been validated in several different ways. The measured value of bright collagen under circularly polarized light depends upon the section thickness, since a linear relationship was found between section thickness and bright areas for a large number of microscopic fields. Plane parallel sections are therefore recommended for this study. The pattern of distribution of bright areas was the same for different observers and different set detection levels in any one section. The pattern found in adjacent sections from the same region of the shaft was identical.

Adult↗
PubMed1988

Determination of inositol phosphates and other biologically important anions by ion chromatography.

Ion chromatography has been applied to the simultaneous, multi-component determination of biologically important anions. More than 20 different biologically important anions were separated on high performance ion-exchange columns and detected using chemically suppressed conductivity. Application of the technique to the separation of inositol mono-, bis-, and trisphosphates shows that these compounds can be separated from the other ions tested and can be detected at concentrations that may be found in vivo. For inositol monophosphate, the conductivity was proportional to the amount of compound from less than 20 pmol to more than 400 nmol. Although alternative methods are available for assaying each of these anions individually, the advantages of ion chromatography lie in the sensitivity of detection, the speed of separation, and the ability to simultaneously determine numerous ions. This method should be broadly applicable to studies of second messengers, measurements of reaction rates, and various metabolic studies.

Carboxylic Acids↗
PubMed2005

Potential of nuclear quadrupole resonance in pharmaceutical analysis.

Nuclear quadrupole resonance is a radio frequency (rf) spectroscopic technique, closely related to NMR, which can be used to detect signals from solids containing nuclei with spin quantum number >1/2. It is nondestructive, highly specific and noninvasive, requires no static magnetic field, and as such is currently used in the detection of explosives and narcotics. Recent technological advances in pulsed NQR methods have shortened detection times, eliminated spurious signals, and enhanced the sensitivity of detection of 14N frequencies, which lie in the low rf range of 0.4-6 MHz, encouraging a wider range of "real world" applications. This Perspective highlights some of the advantages of NQR, the applications in which it could be used, such as the quantification of pharmaceuticals and the identification of polymorphs. Other roles could include detection, analysis, and quality control of pharmaceuticals at all stages of manufacture. Finally, recent advances which enhance even further the sensitivity of detection will be discussed.

Atenolol↗
PubMed1977

[A method for the determination of bromide in urine with an ion-sensitive electrode (author's transl)].

A potentiometric method for determining the concentration of bromide in human urine is described. On account of its specificity and precision, this method is especially suited for the determination of slightly elevated bromide concentrations due to occupational exposure to alkyl bromides. The rate of recovery is 102.5 to 112.5%, and the variability coefficients lie between 5.8 and 8.6%. The detection limit is about 0.013 mmol/l. The concentrations of bromide in the urine of a group of normal persons lie between 0.059 and 0.162 mmol/l.

Adolescent↗
PubMed2003

Automated detection of gray matter malformations using optimized voxel-based morphometry: a systematic approach.

Malformations of cortical development (MCD) are a recognized cause of epilepsy. Their special significance lies in the fact that, once detected and delineated, they are amenable to surgical removal. However, diagnosis from high-resolution MRI is still difficult, time-consuming, and highly dependent on individual expertise. We have recently proposed a simple procedure to detect cortical dysplasias, using automated procedures available within SPM99 (Wellcome Department, University College London, UK). Here, we aimed to systematically determine the best combination of processing parameters, using an optimized voxel-based morphometry approach. We included 20 patients with a known MCD and compared them to a normal database of 53 healthy, age- and gender-matched controls. The approaches taken during spatial normalization and a number of other parameters were systematically altered in order to find the best combination of parameters. Overall, 99 different approaches were evaluated in different ways. As far as possible, automatic processing and evaluation steps were used. With the number of candidate regions for MCD limited to five per patient, the best approaches resulted in the correct identification of up to 16 of 20 malformations. However, a number of approaches failed to perform well. The reasons for these failures and the implications this has for other studies are discussed. We conclude that voxel-based morphometry is able to detect cortical malformations with a high degree of accuracy. However, specific problems seem to arise when using an optimized protocol for voxel-based morphometry, indicating that this protocol may not be optimal for all voxel-based studies on brain morphology. Our approach, involving systematic alterations of parameters and evaluation, may be useful for other studies.

Adolescent↗
PubMed2000

Standardization and quality control of PCR analyses.

In the very beginning of polymerase chain reaction (PCR) tests entering the field of diagnosis of infectious agents, the introduction of this technology into routine diagnosis was hampered by its frequent tendency to create false-positive results because of contamination. This problem is now widely solved by the introduction of the uracil-N-glycosylase (UNG) anticontamination technology. However, care must still be taken to avoid other sources of producing false positive results. They might additionally derive from human error and/or insufficient PCR amplification and detection protocols. A special case lies in the fact that PCR also amplifies DNA from dead organisms rendering a result diagnostically correct as positive, but clinically as false-positive. In PCR, as in any other diagnostic test, the risk of creating a false-negative result also exists. In such a case, the most probable source besides human error, low target or poor amplification and detection protocols is an inhibition caused by interfering substances in a patient's sample. Strategies to recognize and overcome this issue are discussed in this article. Finally a few results from quality control studies on amplification technologies in the diagnosis of infectious agents are reviewed.

False Negative Reactions↗
PubMed2005

Identification of the critical residues involved in peptidoglycan detection by Nod1.

Nod1 is an intracellular pattern recognition molecule activated following bacterial infection, which senses a specific muropeptide (l-Ala-d-Glu-meso-DAP (diaminopimelic acid); "Tri(DAP)") from peptidoglycan. Here we investigated the molecular basis of Tri(DAP) sensing by human (h) Nod1. Our results identified the domain responsible for Tri(DAP) detection in the center of the concave surface of hNod1 leucine-rich repeat domain. Amino acid residues critical for sensing define a contiguous surface patch that is largely conserved in Nod1 proteins from different species. Accordingly, the distinct specificities of human versus murine Nod1 toward muropeptide detection were also found to lie in this central cleft. Several splicing variants of Nod1 lacking repeats 7-9 have been characterized recently, the relative balance of which is thought to correlate with the onset of asthma or inflammatory bowel disease. We demonstrated that these isoforms failed to transduce NF-kappaB activation upon muropeptide stimulation. This study provided insights into the molecular mechanisms responsible for the detection of bacterial peptidoglycan by Nod1 and suggested that defects in Nod1-dependent peptidoglycan sensing may contribute to elicit certain inflammatory disorders.

Adaptor Proteins, Signal Transducing↗
PubMed1986

Regional assignment of Y-linked DNA probes by deletion mapping and their homology with X-chromosome and autosomal sequences.

A series of Y recombinants have been isolated from Y-specific DNA libraries and regionally located on the Y chromosome using a Y deletion panel constructed from individuals carrying structural abnormalities of the Y chromosome. Of twenty recombinants examined twelve have been assigned to Yp and eight to Yq. Five of the Yp recombinants map between Yp11.2 and Ypter and one can only be assigned to Yp. Of the former, four detect homologies on the X chromosome between Xq13 and Xq24 and the latter one between Xp22.3 and Xpter. The sixth recombinant detects autosomal homologous sequences. The six remaining Yp probes are located between Ycen and Yp11.2. One of these detects a homology on the X chromosome at Xq13-Xq24 and a series of autosomal sequences, two detect uniquely Y-specific sequences and three a complex pattern of autosomal homologies. The remaining eight recombinants have been assigned to three intervals on Yq. Of three recombinants located between Ycen and Yq11.21 two detect only Y sequences and one additional autosomal homologies. Two recombinants lie in the interval Yq11.21-Yq11-22, one of which detects only Y sequences and the other an Xp homology between Xp22.3 and Xpter. Finally, the three remaining Yq recombinants all detect autosomal homologies and are located between Yq11.22 and Yq12. The divergence between homologies on different chromosomes has been examined for three recombinants by washing Southern Blots at different levels of stringency. Additionally, Southern analysis of DNA from flow sorted chromosomes has been used to identify autosomes carrying homologies to two of the Y recombinants.

Chromosome Deletion↗
PubMed2003

Detection of spectral signatures in multispectral MR images for classification.

This paper presents a new spectral signature detection approach to magnetic resonance (MR) image classification. It is called constrained energy minimization (CEM) method, which is derived from the minimum variance distortionless response in passive sensor array processing. It considers a bank of spectral channels as an array of sensors where each spectral channel represents a sensor and object spectral signature in multispectral MR images are viewed as signals impinging upon the array. The strength of the CEM lies on its ability in detection of spectral signatures of interest without knowing image background. The detected spectral signatures are then used for classification. The CEM makes use of a finite impulse response (FIR) filter to linearly constrain a desired object while minimizing interfering effects caused by other unknown signal sources. Unlike most spatial-based classification techniques, the proposed CEM takes advantage of spectral characteristics to achieve object detection and classification. A series of experiments is conducted and compared with the commonly used c-means method for performance evaluation. The results show that the CEM method is a promising and effective spectral technique for MR image classification.

Algorithms↗
PubMed1989

Choroideremia and deafness with stapes fixation: a contiguous gene deletion syndrome in Xq21.

The study of contiguous gene deletion syndromes by using reverse genetic techniques provides a powerful tool for precisely defining the map location of the genes involved. We have made use of individuals with overlapping deletions producing choroideremia as part of a complex phenotype, to define the boundaries on the X chromosome for this gene, as well as for X-linked mixed deafness with perilymphatic gusher (DFN3). Two patients with deletions and choroideremia are affected by an X-linked mixed conductive/sensorineural deafness; one patient, XL-62, was confirmed at surgery to have DFN3, while the other patient, XL-45, is suspected clinically to have the same disorder. A third choroideremia deletion patient, MBU, has normal hearing. Patient XL-62 has a cytogenetically detectable deletion that was measured to be 7.7% of the X chromosome by dual laser flow cytometry; the other patient, XL-45, has a cytogenetically undetectable deletion that measures only 3.3% of the X chromosome. We have produced a physical map of the X-chromosome region containing choroideremia and DFN3 by using routine Southern blotting, chromosome walking and jumping techniques, and long-range restriction mapping to generate and link anonymous DNA sequences in this region. DXS232 and DXS233 are located within 450 kb of each other on the same SfiI and MluI fragments and share partial SalI fragments of 750 and greater than 1,000 kb but are separated by at least one SalI site. In addition, DXS232, which lies outside the MBU deletion, detects the proximal breakpoint of this deletion. We have isolated two new anonymous DNA sequences by chromosome jumping from DXS233; one of these detects a new SfiI fragment distal to DXS233 in the direction of the choroideremia gene, while the other jump clone is proximal to DXS233 and detects a new polymorphism. These data refine the map around the loci for choroideremia and for mixed deafness with stapes fixation and will provide points from which to isolate candidate gene sequences for these disorders.

Adolescent↗
PubMed2001

The application of ICP-SMS, GF-AAS and HG-AFS to the analysis of water and sediment samples from a temperate stratified estuary.

Three atomic spectrometry techniques, namely sector field inductively coupled plasma mass spectroscopy, graphite furnace atomic absorption spectrometry and hydride generation atomic fluorescence spectroscopy (ICP-SMS, GF-AAS and HG-AFS, respectively), housed at separate independent laboratories, were used to analyse water and sediment samples collected from the Huon River Estuary, SE Tasmania (Australia) in the Austral spring 1998. A dithiocarbamate-chelation/back-extraction technique was used to separate and preconcentrate Co, Ni, Cu, Zn, Cd and Pb from eight collected water samples prior to analysis by ICP-SMS and GF-AAS. A number of other elements in the waters were analysed directly (Mn, Fe and Zn by GF-AAS; As by HG-AFS), or following sample dilution (1 + 19: V, Mn, Fe, As, Mo, Ba and U by ICP-SMS). Where possible, previously corroborated GF-AAS and HG-AFS techniques were used to verify obtained ICP-SMS results. From the analysis of four reference waters (SLEW-1 and -2, SLRS-3 and NASS-5), good agreement, to within +/- 10-20%, was typically found between certified (or information only values) and measured results (irrespective of analytical technique). Exceptions included Zn (and sometimes Fe) that could not be quantified by ICP-SMS due to elevated blank signals, and As which was found to lie below ICP-SMS detection limits. For Huon Estuary water samples, inter-method agreement was within +/- 10-20% (for those elements amenable to analysis by more than one technique). Nitric acid extracts of two certified reference materials (Buffalo River Sediment and BCSS-1) and six Huon Estuary sediments were analysed by ICP-SMS (for Al, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd and Pb) and HG-AFS (for As). Results from the certified reference materials indicated extraction efficiencies of 60 70% (for most elements). A close correlation between ICP-SMS and HG-AFS was obtained for leachable As in the sediments. In terms of potential inorganic contaminants, the Huon Estuary was found to be a relatively 'clean' water system. The elemental concentrations measured in water and sediment samples from this region were found to lie within current Australian guidelines for estuaries. In general, no one analytical technique was able to accurately determine all elements in all samples from this relatively pristine estuarine environment. A combination of all three analytical techniques was necessary for the successful analysis of the elements considered in this study.

Environmental Monitoring↗
PubMed2006

Chromosomal changes: induction, detection methods and applicability in human biomonitoring.

The objective of this state of the art paper is to review the mechanisms of induction, the fate, the methodology, the sensitivity/specificity and predictivity of two major cytogenetic endpoints applied for genotoxicity studies and biomonitoring purposes: chromosome aberrations and micronuclei. Chromosomal aberrations (CAs) are changes in normal chromosome structure or number that can occur spontaneously or as a result of chemical/radiation treatment. Structural CAs in peripheral blood lymphocytes (PBLs), as assessed by the chromosome aberration (CA) assay, have been used for over 30 years in occupational and environmental settings as a biomarker of early effects of genotoxic carcinogens. A high frequency of structural CAs in lymphocytes (reporter tissue) is predictive of increased cancer risk, irrespective of the cause of the initial CA increase. Micronuclei (MN) are small, extranuclear bodies that arise in dividing cells from acentric chromosome/chromatid fragments or whole chromosomes/chromatids that lag behind in anaphase and are not included in the daughter nuclei in telophase. The cytokinesis-block micronucleus (CBMN) assay is the most extensively used method for measuring MN in human lymphocytes, and can be considered as a "cytome" assay covering cell proliferation, cell death and chromosomal changes. The key advantages of the CBMN assay lie in its ability to detect both clastogenic and aneugenic events and to identify cells which divided once in culture. Evaluation of the mechanistic origin of individual MN by centromere and kinetochore identification contributes to the high sensitivity of the method. A number of findings support the hypothesis of a predictive association between the frequency of MN in cytokinesis-blocked lymphocytes and cancer development. Recent advances in fluorescence in situ hybridization (FISH) and microarray technologies are modifying the nature of cytogenetics, allowing chromosome and gene identification on metaphase as well as in interphase. Automated scoring by flow cytometry and/or image analysis will enhance their applicability.

Cell Division↗