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At least 613 records · Page 34Linked to original sources

PubMed2004

Quantitative detection of methylated SOCS-1 , a tumor suppressor gene, by a modified protocol of quantitative real time methylation-specific PCR using SYBR green and its use in early gastric cancer detection.

Although methylation-specific PCR (MSP) is a sensitive technique in the detection of DNA hypermethylation, it is not quantitative. Here we described a modified PCR protocol to quantify methylated SOCS-1 gene by real time MSP using SYBR green, which involves an additional PCR step after the 72 degrees C extension step. This modified protocol is also useful in the quantitative detection of methylated SOCS-1 gene in serum samples of gastric cancer patients.

Adult↗

PubMed2006

Detection of occult carcinomatous diffusion in lymph nodes from head and neck squamous cell carcinoma using real-time RT-PCR detection of cytokeratin 19 mRNA.

The aim of the present study was to evaluate the occult lymph node carcinomatous diffusion in head and neck squamous cell carcinoma (HNSCC). A total of 1328 lymph nodes from 31 patients treated between 2004 and 2005 were prospectively evaluated by routine haematoxylin-eosin-safran (HES) staining, immunohistochemistry (IHC) and real-time Taqman reverse-transcriptase polymerase chain reaction (real-time RT-PCR) assay. Amplification of cytokeratin 19 (CK19) mRNA transcripts using real-time RT-PCR was used to quantify cervical micrometastatic burden. The cervical lymph node metastatic rates determined by routine HES staining and real-time RT-PCR assay were 16.3 and 36.0%, respectively (P<0.0001). A potential change in the nodal status was observed in 13 (42.0%) of the 31 patients and an atypical pattern of lymphatic spread was identified in four patients (12.9%). Moreover, CK19 mRNA expression values in histologically positive lymph nodes were significantly higher than those observed in histologically negative lymph nodes (P<0.0001). These results indicate that real-time RT-PCR assay for the detection of CK19 mRNA is a sensitive and reliable method for the detection of carcinomatous cells in lymph nodes. This type of method could be used to reassess lymph node status according to occult lymphatic spread in patients with HNSCC.

Adult↗

PubMed2006

Detection of As(III) via oxidation to As(V) using platinum nanoparticle modified glassy carbon electrodes: arsenic detection without interference from copper.

The electrochemical detection of As(III) was investigated on a platinum nanoparticle modified glassy carbon electrode in 1 M aqueous HClO4. Platinum nanoparticle modified glassy carbon electrodes were prepared by potential cycling in 0.1 M aqueous KCl containing 1 mM K2PtCl6. In each potential cycle, the potential was held at + 0.5 V for 0.01 s and at -0.7 V for 10 s. 25 cycles were optimally used to prepare the electrodes. The resulting electrode surfaces were characterized with AFM. The response to arsenic(III) on the modified electrode was examined using cyclic voltammetry and linear sweep voltammetry. By using the As(III) oxidation peak for the analytical determination, there is no interference from Cu(II) if present in contrast to the other metal surfaces (especially gold) typically used for the detection of arsenic; Cu(II) precludes the use of the As(0) to As(III) peak for quantitative anodic stripping voltammetry measurements due to the formation of Cu3As2 and an overlapping interference peak from the stripping of Cu(0). After optimization, a LOD of 2.1 +/- 0.05 ppb was obtained using the direct oxidation of As(III) to As(V), while the World Health Organization's guideline value of arsenic for drinking water is 10 ppb, suggesting the method may have practical utility.

Journal Article↗

PubMed1999

Immunocytological detection of isolated tumour cells in the bone marrow of malignant melanoma patients: a new method for the detection of minimal residual disease.

AIMS: Immunocytologically detected isolated tumour cells indicate a poor prognosis. This has been shown in breast, gastrointestinal and lung cancer, and might thereby help to indicate adjuvant therapy. Immunocytology has been proved to be a reliable technique and enables a phenotypic tumour cell characterization. We find this technique superior to molecular biological techniques such as reverse transcriptase polymerase chain reaction RT-PCR. So far, immunocytological studies have not been performed in malignant melanoma patients and our study aimed to establish this approach in melanoma patients. METHODS: Twenty melanoma patients who underwent surgery for lymph-node metastasis using a radical lymphadenectomy were studied. Using the immunoperoxidase method, cytospins of bone marrow aspirates (1.5x10(6)cells per patient) were stained with the monoclonal antibody HMB-45. Nineteen patients who were surgically treated but did not suffer from malignant melanoma were included as a control group. RESULTS: Four of the 20 patients showed isolated tumour cells in the aspirate. Three of these patients had stage IV disease. One patient had a stage III tumour (1/7; 14.3%). One patient was classified as stage II and did not show tumour cells in the bone marrow. No staining cells were found in the control group (n=19). CONCLUSIONS: Our study demonstrates that the immunocytological approach can be used as a new technique to detect occult tumour cell dissemination in malignant melanoma patients and supports previous findings in carcinoma of the stomach, colon, pancreas and other tumours.

Adult↗

PubMed1988

[Clinical detection of 2,511 breast cancers 1977-1986. Efficiency of legal early cancer detection studies].

From 1977 to 1986, inclusively, 2511 patients with breast cancer were analysed. The following factors were evaluated: patients attitude toward screening programs, the method of cancer detection, the relation between tumor-size and axillary nodes metastases and efficiency of the currently in Germany used screening program. 65.9% of the patients underwent regular annual preventive physical examination, 15.2% irregular and 18.9% no examination. Only 12.7% of cancers were detected through the screening program, in 85% the patients discovered their tumors. Cancers up to 0.5 cm had in 25% lymph-nodes metastases and tumors up to 1.0 cm had in 27% of cases axillary nodes metastases. Breast cancers between 1.1 cm and 2.0 cm had a bad prognosis: the axillary metastases occurred in 34%-45%. Surprisingly, there were no differences in tumor size, percentage of residual tumor and frequency of axillary lymph-nodes metastases between patients who took regularly part in preventive physical examination and those never taking part. Women who irregularly participated in the program had the most unfavourable prognosis.

Biopsy↗

PubMed1989

Favourable effect of detergent on antigen detection and comparison of enzyme linked detection systems in an ELISA for Chlamydia trachomatis.

The influence of addition of detergents to the antigen on sensitivity of an ELISA for the detection of Chlamydia trachomatis was investigated. Of the detergents tested, only octyl-beta-d-glucopyranoside and sodiumdesoxycholate gave respectively a two- to fourfold and an eightfold increase in sensitivity. The effect was only present within a narrow range of detergent concentrations. The optimal detergent concentration was strongly dependent on the protein concentration in the antigen preparation. For optimal detection of the bound chlamydial antigen, enzyme and biotin labeled secondary antibodies were compared. The biotin labeled antibodies were combined with enzyme labeled streptavidin-biotin complex (SBC). Color development was obtained with both types of conjugates by using either o-phenylenediamine (OPD) or an enzyme amplification system. The best results were obtained with the SBC method and OPD.

Antigens, Bacterial↗

PubMedDate not supplied

Detection of o-tyrosine in irradiated chicken by reverse-phase HPLC and fluorescence detection.

A method for the measurement of o-tyrosine in irradiated chicken has been developed. The procedure involves the solvent extraction and removal of free o-tyrosine, which is present in unirradiated tissue, followed by acid hydrolysis of bound o-tyrosine in the proteinaceous residue and measurement of the cleaved residues by HPLC with fluorescence detection. Bound o-tyrosine was not detected above 0.01 mg/kg in unirradiated tissue but was observed, in increasing amounts of up to 5.18 mg/kg, when the tissue was irradiated at doses of between 2.5 and 20 kGy. The precision of the analysis was assessed by duplicate determinations, the agreement between duplicates and their respective means averaged 1.7% as defined by the term [(a-b)/(a+b)] x 100% where a and b are the repeat determination values.

Animals↗

PubMed2005

Estimation of a method detection limit for an in vivo XRF arsenic detection system.

An x-ray fluorescence measurement system has been developed with an 125I source to detect arsenic in superficial layers of phantoms and tissue. Based on in vivo measurements, in conjunction with Monte Carlo simulations, the detection limit for arsenic in skin ranges between 2.6+/-0.5 and 5.7+/-1.1 microg g(-1), depending on skin thickness and assuming that arsenic is uniformly distributed in the skin. The effect of skin arsenic distribution was also examined.

Arsenic↗

PubMedDate not supplied

Detection of alcohol misuse using a routine test panel: the early detection of alcohol consumption (EDAC) test.

AIMS: This study describes the derivation and validation of the early detection of alcohol consumption (EDAC) test, which uses linear discriminant function (LDF) analysis for the identification of alcohol misuse. This form of LDF aims to predict a categorical dependent variable (alcohol misuse) on the basis of several independent, predictor variables (routine laboratory tests). METHODS: EDAC was developed to classify individuals as heavy or light drinkers using a database of 1599 subjects recruited from 25 sites in the USA. The predictor variables for the LDF were 36 routine chemistry and haematology analytes. RESULTS: The EDAC model produced 80.7% sensitivity and 84.4% specificity, with an overall correct classification rate of 82.5%. Using a stepwise method, 20 of the 36 routine tests used in the LDF were selected as the optimal predictor variables. The top three variables with the highest contribution in the stepwise EDAC model were: bilirubin ratio (direct to total), aspartate aminotransferase and albumin. CONCLUSIONS: This study shows that LDF analysis in conjunction with new, user-friendly computer packages is a practical and cost-effective laboratory tool for detecting excessive drinking using blood constituents ordered routinely in a variety of clinical settings. Diagnostic performance can be adjusted to achieve higher specificity rates.

Adolescent↗

PubMed1997

A theoretical framework for evaluating the sensitivity of surveillance for detecting wild poliovirus: I. Factors affecting detection sensitivity in a person with acute flaccid paralysis.

Surveillance for cases of acute flaccid paralysis provides a means for detecting circulating wild poliovirus in a population and therefore is crucial to the global polio eradication effort. An initial step toward developing a more general framework for understanding the sensitivity of the acute flaccid paralysis surveillance system is presented by first specifying four categories of sensitivity involved: laboratory sensitivity, specimen sensitivity, person sensitivity, and population sensitivity. Using this framework, estimates for specimen sensitivity (the probability that virus will be detected in a specimen collected from an infected person) and the prevalence of infection are derived and applied to surveillance data from three regions. On the basis of the framework, our analysis indicates that a second specimen may significantly increase person sensitivity under some circumstances but provides little improvement under others.

False Negative Reactions↗

PubMed1996

Detection of the mec-A gene and phenotypic detection of resistance in Staphylococcus aureus isolates with borderline or low-level methicillinresistance.

Eighty-three isolates of Staphylococcus aureus for which MICs of methicillin of 4-16 mg/L had previously been recorded were tested for the presence of the mecA gene with a DNA probe and a PCR assay. There was complete agreement between the results obtained by these methods; 39 isolates were mecA-positive and 44 were mecA-negative. Using the presence of mecA as the defining standard, several phenotypic methods for determining resistance to methicillin were evaluated and a high-inoculum, agar-incorporation breakpoint test was found to offer the best combination of high sensitivity and high specificity. However twenty-seven of the 44 mecA-negative strains were methicillin-resistant according to agar dilution MICs (MIC > 4 mg/L on at least one of the four media used) but none had MICs exceeding 32 mg/L. One of the mecA-positive strains had a methicillin MIC of only 8 mg/L and did not appear to be heteroresistant. The clinical significance of these two groups of 'atypical' isolates may need further investigation. This study highlights the problems of detecting reliably S. aureus with low level methicillin resistance by phenotype methods and the usefulness of direct detection of the mecA gene.

Bacterial Proteins↗

PubMed1998

Swelling detection for volume regulation in the primitive eukaryote Giardia intestinalis: a common feature of volume detection in present-day eukaryotes.

It is increasingly evident that cell swelling is associated with the triggering of many biological processes, including progression of the cell cycle, hormonal response, and gene expression. However, the mechanism by which cell swelling is initially sensed and converted into intracellular signals is still ill-defined. We report here an early event in the detection of cell swelling and initiation of the volume regulatory response in Giardia intestinalis, an ancient representative of the eukaryotic kingdom. Giardial cell swelling, irrespective of the extent, was sensed at a cell volume of 1.06 x isosmotic volume (the threshold volume), at which the transition of the volume regulatory transport system from the 'resting' to the 'open' state occurred. Irreversible modification by p-chloromercuribenzoate (pCMB) and N-ethylmaleimide (NEM) of reduced thiols affected the threshold volume, but in opposing manners: pCMB increased the threshold volume to 1.14 x and NEM decreased to 0.85 x isosmotic volume. The simple modification of the threshold volume by NEM caused a drastic reduction of giardial cell volume under isosmotic conditions, with a process strikingly similar to the opening of mitochondrial permeability transition pore, a causative event in stress-induced programmed cell death. Substantial evidence supports the hypothesis that modulation of the membrane thiol moieties at the threshold volume, causing the 'all-or-nothing' type of swelling detection, represents the event linking cell swelling to the second messenger systems for volume regulation in present eukaryotes. Pathophysiological implications of alteration of the threshold volume are discussed.

Alanine↗

PubMed1991

Carrier detection and prenatal diagnosis in 98 families of haemophilia A by linkage analysis and direct detection of mutations.

489 individuals from 98 families with a haemophilia A member were studied with restriction fragment length polymorphisms (RFLPs) for carrier detection and prenatal diagnosis. Five intragenic polymorphisms revealed with the restriction enzymes BclI, XbaI, BglI, HindIII and AlwNI and one extragenic multiallelic polymorphism (St14) at the DXS52 locus were used. The combination of the five intragenic polymorphisms did not add significantly more information than just the BclI and XbaI polymorphisms because of strong linkage disequilibrium. The sequences surrounding the intronic restriction sites of the BclI and XbaI RFLPs are known so they can be rapidly analysed using the polymerase chain reaction (PCR). 68.6% of the women were heterozygous for either the BclI or XbaI RFLP and this heterozygosity rate increased to 98.6% when the St14 extragenic polymorphism was included. Linkage analysis using these RFLPs led to the classification of over 90% of the women as carriers or normal and 98.6% of the carriers were heterozygous. Prenatal diagnosis was successful in the 16 foetuses tested and all could be classified as carrier, normal or haemophiliac. Five TaqI restriction sites in the coding region of the factor VIII gene can detect a C to T transition that results in an in-frame stop codon. These five sites were amplified by PCR in 119 haemophiliacs and tested for an abnormal TaqI restriction pattern. A stop codon was found in three haemophiliacs at exons 18, 22 and 24. The same analysis revealed three deletions, two involving the last exon 26 and one exons 23-26.

Alleles↗

PubMed1993

Human kidney: endothelin isoforms detected by HPLC with radioimmunoassay and receptor subtypes detected using ligands BQ123 and BQ3020.

Animal kidneys are exquisitely sensitive to the effects of endothelin (ET), but little is known of its binding characteristics, isoform prevalence, or receptor subtype distribution in human kidney. We investigated these parameters using high-performance liquid chromatography, radioimmunoassay (RIA), and the recently synthesized ETA and ETB receptor-selective peptide ligands BQ123 (cyclo[D-Asp-L-Pro-D-Val-L-Leu-D-Trp-]) and BQ3020 (Ala11,15-Ac-ET-1[6-21]). Fresh-frozen normal segments of kidneys excised for carcinoma were solid-phase-extracted using Amprep C2 columns, and parallel eluates were oxidized. All were subjected to RIA for ET and pro-ET-1, in triplicate. ET isoforms were characterized by RP-HPLC and subsequent RIA of eluates. Total amounts of immunoreactive ET were 6.9 +/- 3.8 and 4.5 +/- 1.6 pmol/g wet weight in medulla and cortex, respectively. Reverse-phase high performance liquid chromatography showed peaks of immunoreactivity with retention times identical to synthetic ET-1 and metsulphoxide ET-1. ET-2, ET-3, and pro-ET-1 were not detected. Saturation assays using 0.01-8.0 nM 125I-ET-1 or 125I-BQ3020, gave Kd values (mean +/- SEM) of 0.17 +/- 0.04 and 0.36 +/- 0.06 nM, respectively, with Bmax values of 57.7 +/- 15.4 and 30.0 +/- 5.0 fmol/mg protein, respectively. Hill coefficients were 0.86 +/- 0.03 and 0.77 +/- 0.04, but a two-site fit was not preferred. Receptor autoradiography has detected both subtypes, mainly present in medulla, with ETB predominating.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1995

Statistical pitfalls in detecting age-of-onset anticipation: the role of correlation in studying anticipation and detecting ascertainment bias.

Attempts to detect anticipation in datasets have been hampered by two statistical problems: confusion about the role of correlation, and ascertainment bias. We show three things. (1) Correlation and anticipation are two distinct phenomena, such that neither high nor low correlation necessarily reveals anything about anticipation. (2) Nor does correlation analysis (or its cousin, regression analysis) offer a way to detect ascertainment bias, as has been suggested. Demonstration of "regression to the mean" does not necessarily indicate the presence of ascertainment bias, either. (3) Finally, under certain special circumstances, one can test for anticipation without regard for ascertainment bias. However, these circumstances are limited and may prove of little practical value.

Adult↗

PubMed1999

Automatic cardiac LV boundary detection and tracking using hybrid fuzzy temporal and fuzzy multiscale edge detection.

This paper describes a new fully automatic fuzzy multiresolution-based algorithm for cardiac left ventricular (LV) epicardial and endocardial boundary detection and tracking on a sequence of short axis (SA) echocardiographic images of a complete cardiac cycle. This is a necessary step for automatic quantification of cardiac function using echo images. The proposed method is a "center-based" approach in which epicardial and endocardial boundary edge points are searched for on radial lines emanating from the LV center point. The central point of the LV cavity is estimated using a fuzzy-based technique in which the "uncertain" spatial, morphological, and intensity information of the image are represented as fuzzy sets and then combined by fuzzy operators. Edge-detection stage uses multiscale spatial and temporal information in a fuzzy multiresolution framework to identify a single moving edge point for each one of the epicardial and endocardial boundaries over the M radii in the N frames of a complete cardiac cycle. The raw extracted edge points are then processed in the wavelet domain to reduce the effects of noise from the boundaries and papillary muscles from the endocardial boundary extraction process. Finally, a uniform cubic B-spline approximation method is used to define the closed LV boundaries. Experiments with simulated and real echocardiographic images are presented.

Algorithms↗

PubMed2001

A low-cost fiber-optic instrument to colorimetrically detect patients with Barrett's esophagus for early detection of esophageal adenocarcinoma.

In Barrett's esophagus, the precursor to esophageal adenocarcinoma, the squamocolumnar junction (SCJ) between the normal esophagus and the stomach like mucosa is proximally displaced. Currently it can be detected only by an expensive upper GI endoscopic procedure. We have developed a minimally invasive and easy to operate colorimetric instrument for the low-cost detection of Barrett's esophagus. The instrument is based on a flexible, narrow diameter, fiber-optic probe that performs a colorimetric scan of the esophageal lumen. The instrument was clinically evaluated in 50 subjects. The instrument could identify both symmetric and asymmetric SCJ's. The SCJ locations determined by the colorimetric instrument correlated strongly (R2 = 0.89) with those determined by endoscopy. The instrument identified the SCJ locations accurately (Mean of difference +/- SEM: 0.97 +/- 1.72 cm) and reproducibly (Mean of absolute difference +/- SEM: 1.33 +/- 1.40 cm). The instrument has a 90% sensitivity of identifying patients with Barrett's esophagus, based on the clinical algorithm that if the SCJ is located at a distance less than 37 cm from the teeth, then the subject has Barrett's esophagus, otherwise the subject does not have Barrett's esophagus. In conclusion, the colorimetric instrument has the potential of being a cost-effective way of determining patients likely to have Barrett's esophagus in the population.

Adenocarcinoma↗

PubMed2005

Ultrawideband microwave breast cancer detection: a detection-theoretic approach using the generalized likelihood ratio test.

Microwave imaging has been suggested as a promising modality for early-stage breast cancer detection. In this paper, we propose a statistical microwave imaging technique wherein a set of generalized likelihood ratio tests (GLRT) is applied to microwave backscatter data to determine the presence and location of strong scatterers such as malignant tumors in the breast. The GLRT is formulated assuming that the backscatter data is Gaussian distributed with known covariance matrix. We describe the method for estimating this covariance matrix offline and formulating a GLRT for several heterogeneous two-dimensional (2-D) numerical breast phantoms, several three-dimensional (3-D) experimental breast phantoms, and a 3-D numerical breast phantom with a realistic half-ellipsoid shape. Using the GLRT with the estimated covariance matrix and a threshold chosen to constrain the false discovery rate (FDR) of the image, we show the capability to detect and localize small (<0.6 cm) tumors in our numerical and experimental breast phantoms even when the dielectric contrast of the malignant-to-normal tissue is below 2:1.

Algorithms↗