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At least 253 records · Page 14Linked to original sources
PubMed1988

Direct detection of Mycoplasma pneumoniae antigen in clinical specimens by a monoclonal antibody immunoblot assay.

Throat swabs from patients with pharyngitis and sputum specimens from patients with atypical pneumonia were tested for the presence of a Mycoplasma pneumoniae polypeptide with a molecular weight of 43,000 with the use of an M. pneumoniae species-specific monoclonal antibody in an immunoblot assay. This 43,000-dalton polypeptide was detectable in 33 of 33 throat swabs from patients with pharyngitis that were positive for M. pneumoniae by conventional culture as well as a culture-amplified enzyme immunoassay. The 43,000-dalton polypeptide was also detected in three of three M. pneumoniae culture-positive sputum specimens. It was not detected in 3 sputum specimens culture-confirmed for Legionella pneumophila, 10 sputum specimens from normal persons, or 25 throat swabs also from normal persons. This immunoblot assay could be completed within five hours and may be an alternative method for detecting M. pneumoniae antigen directly in sputum or throat swab specimens.

Adult↗
PubMed2003

Direct detection of Vibrio cholerae and ctxA in Peruvian coastal water and plankton by PCR.

Seawater and plankton samples were collected over a period of 17 months from November 1998 to March 2000 along the coast of Peru. Total DNA was extracted from water and from plankton grouped by size into two fractions (64 micro m to 202 micro m and >202 micro m). All samples were assayed for Vibrio cholerae, V. cholerae O1, V. cholerae O139, and ctxA by PCR. Of 50 samples collected and tested, 33 (66.0%) were positive for V. cholerae in at least one of the three fractions. Of these, 62.5% (n = 32) contained V. cholerae O1; ctxA was detected in 25% (n = 20) of the V. cholerae O1-positive samples. None were positive for V. cholerae O139. Thus, PCR was successfully employed in detecting toxigenic V. cholerae directly in seawater and plankton samples and provides evidence for an environmental reservoir for this pathogen in Peruvian coastal waters.

Bacterial Proteins↗
PubMed2005

Direct detection of Nocardia spp. in clinical samples by a rapid molecular method.

We developed a 16S PCR-based assay for the rapid detection of Nocardia spp. directly from human clinical samples. The applicability of the assay was confirmed by using 18 samples from patients with nocardiosis as diagnosed by conventional cultures and 20 clinical samples from patients with confirmed tuberculosis used as negative controls.

Biopsy↗
PubMed2001

Detecting direction of coupling in interacting oscillators.

We propose a method for experimental detection of directionality of weak coupling between two self-sustained oscillators from bivariate data. The technique is applicable to both noisy and chaotic systems that can be nonidentical or even structurally different. We introduce an index that quantifies the asymmetry in coupling.

Journal Article↗
PubMed1994

[Direct detection of an antigen in immunoglobulin G Langmuir-Blodgett films based on a surface plasma resonance method and in a piezoelectric system].

The possibilities of direct antigen detection in unlabelled systems based on immunoglobulin G Langmuir-Blodgett films as a sensitive surface have been studied. It was shown that an increase in the monolayer number in an immunoglobulin G Langmuir-Blodgett film deposited onto a solid surface coated with a thin silver film (50 nm) resulted in the regeneration of the antigen-binding capacity of the upper antibody layer. This dependence can be used for the construction of a direct optical immunosensor based on surface plasmon resonance. Moreover, a model of a piesoelectric immunosensor on the basis of immunoglobulin G Langmuir-Blodgett films for direct ferritin detection has been proposed. The detection range of ferritin concentrations in solution is 10(-10)-10(-7) M.

Animals↗
PubMed1990

A new approach to the direct detection of free radicals in the intact myocardium.

A new method for the direct ESR detection of free radicals in rat myocardial tissue is described. Isolated rat atria are continuously monitored for heart rate and contractile force; at the end of the experimental period the beating organs are inserted into quartz ESR tubes and immediately frozen in liquid nitrogen. Spectra obtained from these preparations show the presence of very weak radical signals. When ESR spectra are recorded on samples obtained from pools of rat atria pulverized under liquid nitrogen, the radical lines are markedly stronger than those observed for intact organs; contaminating metals are also frequently detected. These findings indicate that crushing or grinding procedures carried out under liquid nitrogen produce artifactual ESR active species. The new method described in the present paper does not involve mechanical interventions and therefore should yield reliable artifact-free results.

Animals↗
PubMedDate not supplied

A comparison of commercially available monoclonal antibodies for direct and indirect immunofluorescence culture confirmation and direct detection of parainfluenza viruses.

Two commercially available immunofluorescence monoclonal antibody (MAB) reagents (Bartels, Baxter Healthcare, Issaquah, WA; and Symex, Broken Arrow, OK) were evaluated as a means for detecting parainfluenza virus (PIV) both in shell-vial cultures and directly in clinical specimens. Bartels reagents are used in an indirect immunofluorescence assay (IFA) format and exist as MABs reactive with all three PIV serotypes, individually and in a pool. Symex reagents, also available individually and in a trivalent pool, are used in a direct immunofluorescence assay (DFA) format. Among a total of 299 respiratory specimens, 24 yielded PIV. In a shell-vial culture confirmation test, both the individual and pooled monoclonal antibody reagents from both Bartels and Symex detected all 24 PIV isolates. There were three apparent false-positive results with the Bartels pooled IFA reagents. Of the 299 specimens, 160 were also tested directly for the presence of PIV. There were 13 positive specimens among these 160. The Bartels and Symex monoclonal antibody reagents detected similar percentages of positive samples when used for direct detection (that is, 78.6-85.7). No false-positive results were obtained with any of the reagents in the direct-detection format.

Antibodies, Monoclonal↗
PubMed1999

Direct detection of Prevotella intermedia and P. nigrescens in suppurative oral infection by amplification of 16S rRNA gene.

A specific 16S rDNA PCR and subsequent hybridisation reaction was designed to discriminate between strains of Prevotella intermedia (n = 15) and P. nigrescens (n = 15). This technique was then used to detect the presence of these two bacterial species in acute suppurative oral infection. A total of 36 pus samples aspirated from 26 peri-apical abscesses, three root canals, three periodontal abscesses, two cases of refractory periodontitis, one cyst and one haematoma was examined. A portion of the pus sample was processed by PCR and the remainder of the specimen was subjected to routine culture. The PCR-based technique gave an identical pattern of detection of P. intermedia or P. nigrescens to that obtained by culture for 30 of the 36 specimens. Either P. intermedia or P. nigrescens was present in 14 samples and neither species was detected in 16 samples. In the remaining six samples the PCR method indicated the presence of one (n = 3) or both (n = 3) of the Prevotella species but neither or only one species was isolated by culture. It is concluded that the presence of P. intermedia and P. nigrescens in pus can be detected rapidly and specifically by direct PCR amplification of 16S rDNA. P. nigrescens was detected more frequently than P. intermedia in suppurative peri-apical infection both by culture and PCR.

Bacteroidaceae Infections↗
PubMed1987

The simultaneous direct detection of Mycoplasma pneumoniae and Legionella pneumophila antigens in sputum specimens by a monoclonal antibody immunoblot assay.

An immunoblot (Western) assay was developed employing a species-specific monoclonal antibody to a 43 kDa Mycoplasma pneumoniae membrane polypeptide and a species-specific monoclonal antibody to 29 kDa Legionella pneumophila outer membrane protein. This assay could simultaneously detect these two different antigens directly in sputum. The 43 kDa M. pneumoniae antigen was detected by this assay in each of three M. pneumoniae culture-confirmed sputum specimens. In addition, the 29 kDa L. pneumophila antigen was detected in three of three L. pneumophila culture-confirmed sputum specimens. Neither of these two specific antigens were detected in induced sputum specimens from ten normal individuals.

Antibodies, Monoclonal↗
PubMed1989

TestPack Chlamydia, a new rapid assay for the direct detection of Chlamydia trachomatis.

TestPack Chlamydia (Abbott Laboratories) is a rapid enzyme immunoassay for the direct antigen detection of Chlamydia trachomatis in endocervical specimens. The assay is self-contained, requires no specialized equipment, and yields results in less than 30 min. The clinical performance of TestPack Chlamydia versus chlamydial cell culture was evaluated with a total of 1,694 paired endocervical specimens. Discordant samples were further investigated by immunofluorescent staining and by Chlamydiazyme immunoassay, with confirmatory procedures. The sensitivity of TestPack Chlamydia with less-than-48-h-old specimens was 76.5%, while culture sensitivity was 86.7%. TestPack Chlamydia specificity was determined to be 99.5%. These results indicate that TestPack Chlamydia is an accurate test for chlamydial infection, with a positive predictive value of 96.2%. This assay is suitable for low-volume chlamydial testing in physician offices, clinics, and smaller laboratories.

Antigens, Bacterial↗
PubMed2005

Detection, direction discrimination, and off-frequency interference of center-frequency modulations and glides for vowel formants.

Vowels are mainly classified by the positions of peaks in their frequency spectra, the formants. For normal-hearing subjects, change detection and direction discrimination were measured for linear glides in the center frequency (CF) of formantlike sounds. A CF rove was used to prevent subjects from using either the start or end points of the glides as cues. In addition, change detection and starting-phase (start-direction) discrimination were measured for similar stimuli with a sinusoidal 5-Hz formant-frequency modulation. The stimuli consisted of single formants generated using a number of different stimulus parameters including fundamental frequency, spectral slope, frequency region, and position of the formant relative to the harmonic spectrum. The change detection thresholds were in good agreement with the predictions of a model which analyzed and combined the effects of place-of-excitation and temporal cues. For most stimuli, thresholds were approximately equal for change detection and start-direction discrimination. Exceptions were found for stimuli that consisted of only one or two harmonics. In a separate experiment, it was shown that change detection and start-direction discrimination of linear and sinusoidal formant-frequency modulations were impaired by off-frequency frequency-modulated interferers. This frequency modulation detection interference was larger for formants with shallow than for those with steep spectral slopes.

Auditory Threshold↗
PubMed1995

Direct detection of recombinant gene expression by two genetically engineered yeasts in soil on the transcriptional and translational levels.

The expression of a recombinant gene by yeasts seeded into soil samples was directly measured by analyzing transcripts and gene product occurrences in soil extracts. Two yeast species, Saccharomyces cerevisiae WHL292 and Hansenula polymorpha LR9-Apr4, both engineered by a synthetic gene sequence encoding the mammalian peptide aprotinin, produced and secreted this peptide in batch cultures at concentrations of 90 and 64 ng ml-1, respectively. In S. cerevisiae, the aprotinin gene was located on plasmid p707 and expressed constitutively. H. polymorpha carried the gene chromosomally integrated, and its expression was inducible by methanol. To detect aprotinin transcripts, cells were directly lysed in the soil samples and the crude lysates were hybridized to oligo(dT)-coated magnetized polystyrene beads (Dynabeads). After separation and purification in a magnetic field, aprotinin mRNA was detected by reverse transcriptase PCR with aprotinin gene-specific primers. Transcripts from 10 cells g of soil-1 were sufficient for detection. When 10(7) cells of S. cerevisiae were inoculated into soil, aprotinin mRNA was detectable during the first 4 days. Addition of methanol and a combined nutrient solution was necessary to induce aprotinin gene expression of H. polymorpha in soil. Aprotinin could be detected directly in soil extracts by an indirect enzyme-linked immunosorbent assay with monoclonal aprotinin-specific antibodies. The detection threshold was 45 pg g of soil-1. In presterilized soil inoculated with S. cerevisiae (10(6) CFU g-1), aprotinin accumulated during the first 10 days to 12 ng g of soil-1 and then remained constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Direct detection of 16S rRNA using oligonucleotide microarrays assisted by base stacking hybridization and tyramide signal amplification.

A simple method has been developed and validated for direct, sensitive detection and specific identification of 16S rRNA. We first report our direct investigation of discrimination efficiency for sequence variations in RNA using oligonucleotide microarrays assisted by base stacking hybridization, and demonstrate that the sequence variations of double base substitution, single base substitution and single base deletion in RNA could be directly identified. With the help of tyramide signal amplification (TSA), the detection sensitivity of this method for four clinically important bacterial species was below 0.5, 5, 1 and 1 ng of total RNA, which are 100-1000 fold more sensitive than the published methods.

DNA Probes↗
PubMed2003

Direct detection of Actinomyces spp. from infected root canals in a Chinese population: a study using PCR-based, oligonucleotide-DNA hybridization technique.

OBJECTIVES: The poor sensitivity of phenotypic identification techniques has hampered the taxonomic differentiation of Actinomyces. Hence we developed a sensitive and specific, PCR-based oligonucleotide-DNA hybridization technique to detect Actinomyces spp. and, used this method to detect these organisms in samples directly obtained from infected root canals. METHODS: A total of 32 samples from 28 Chinese patients, with primary root canal infections, aseptically exposed at the first patient visit, were studied. Whole bacterial genomic DNA was isolated directly from paper point samples. The variable regions of 16S ribosomal DNA of bacteria were amplified and labeled with digoxigenin for further hybridization and detection. A total of seven oligonucleotide probes specific for A. bovis, A. gerencseriae, A. israelii, A. meyeri, catalase-negative A. naeslundii (genospecies 1 and 2), catalase-positive A. naeslundii genospecies 2 and A. odontolyticus were used. RESULTS: 16 of the 32 teeth were infected with one or more Actinomyces species. The prevalence rates of the examined species were: A. odontolyticus 31.3%, A. meyeri 9.4%, A. naeslundii 9.4%, A. israelii 6.3% and A. gerencseriae 3.1%; no A. bovis was detected in any of the canals. Furthermore, A. odontolyticus was isolated more frequently from root canals with caries or a history of caries (Fisher's exact test: P=0.0496; Odds ratio=9.00, 95% confidence interval: 0.97-83.63), and A. naeslundii was significantly associated with traumatized teeth (Fisher's exact test: P=0.0121; Odds ratio=57.00, 95% confidence interval: 2.10-1546.90). However, no significant correlation was found between Actinomyces spp. and clinical symptoms and signs, such as pain, swelling, percussion to tenderness, sinus and periapical radiolucency. CONCLUSION: Actinomyces spp. may be important pathogens of root canal infections. A. naeslundii in particular may be related with traumatized teeth. A. odontolyticus appears to be involved in infections related to caries, exposure of dentinal tubules during cavity preparation and/or leaking restoration, but further clarification with large samples is necessary.

Actinomyces↗
PubMed2002

[Direct detection of mycobacterium tuberculosis complex in clinical specimens by gen-probe amplified direct test].

The amplified Mycobacterium tuberculosis direct test (MTD) (Gen-Probe Inc., San Diego, CA, USA) is a rapid technique of nucleic acid amplification which can be used directly on processed clinical specimens. It is based on the enzymatic amplification of ribosomal RNA via DNA intermediates, with detection of amplified product by an acridinum-ester-labeled DNA probe. The purpose of this study was to evaluate the clinical utility of this test for diagnosis of tuberculosis by comparing the sensitivity and specificity of the test with acid-fast smear, mycobacterial culture and clinical evaluation. The study included 399 specimens from patients, suspected of Tb which were submitted to the microbiological laboratory of our Institute over a 12 months period. Compared with bacterioscopy, conventional culture on L-J and rapid systems of cultivation (Bactec-450 Tb, MB/Bact, Bactec 960 MGIT) MTD had a sensitivity 93.2% and specificity 98.5%. We conclude, that MTD test which is completed within 6-8 hours, when used rationally, mainly in conjunction with routine smear and culture is a useful, rapid diagnostic test for suspected tuberculosis patients.

Bacteriological Techniques↗
PubMed1997

Direct detection of Mycobacterium tuberculosis complex in nonrespiratory specimens by Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test.

The Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test (AMTDT) was adapted for the detection of Mycobacterium tuberculosis complex in 224 nonrespiratory specimens from 188 patients. The sensitivity and specificity of the AMTDT for such specimens, after resolution of discrepant results, were 85.7 and 100%, respectively. Pretreatment of nonrespiratory specimens with sodium dodecyl (lauryl) sulfate is mandatory to obtain consistent and reproducible AMTDT results. The use of 500 microliters of decontaminated specimen improves the sensitivity of the test. Because the AMTDT detects stable rRNA from noncultivable bacilli, it is not useful for monitoring patients receiving treatment.

Bacterial Typing Techniques↗
PubMed1996

Direct detection of Epstein-Barr viral antigen in nasopharyngeal swabs from patients with infectious mononucleosis.

OBJECTIVE: To determine whether direct immunologic detection of Epstein-Barr virus (EBV) early antigen diffuse component (EA-D) from nasopharyngeal swabs is a feasible approach to the development of a rapid diagnostic test for infectious mononucleosis (IM). METHODS: Nasopharyngeal swabs from 20 patients presenting with a presumptive diagnosis of IM (having the classic triad of symptoms-acute pharyngitis, fever, and lymphadenopathy) and 5 controls were assayed for EA-D. EBV serologic testing and a heterophil antibody titer (HAT) test also were performed. EA-D was assayed by polyacrylamide gel electrophoresis and subsequent transfer to a nylon membrane, followed by immunoblotting with a monoclonal antibody. RESULTS: EA-D was detected in 17 of 20 patients (85%) with presumptive diagnoses of IM and in 1 of 5 normal subjects and was highly significant in predicting IM (p < 0.01). There was no significant difference in numbers of positive and negative results using either EA-D assay or HAT test in patients with IM (p < 0.35). Pharyngeal exudate in the 17 pharyngitis patients with this variable documented was significantly correlated with positive EA-D (p < 0.01), but not with the HAT test (p < 1.00). CONCLUSIONS: Immunologic detection of EBV-derived antigens from nasopharyngeal swabs is a potential early diagnostic tool for clinically suspected IM. Sensitivity and specificity in pediatric and adult populations, patients with other viral etiologies, and patients with streptoccocal pharyngitis should be determined in subsequent investigations.

Adolescent↗