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PubMed2003

Characteristics and treatment outcomes of leprosy patients detected during a leprosy elimination campaign in Mozambique compared with routinely detected patients.

The objective of this study is to assess whether the case-finding method is a determinant for diagnostic characteristics and treatment outcome of newly diagnosed leprosy patients in Northern Mozambique. This is a retrospective cohort study of 3202 patients on the differences between entrance characteristics and treatment outcome in self-reporting patients and patients detected during a leprosy elimination campaign (LEC) in 1999 in Northern Mozambique. As a consequence of LEC activities, 3 times more patients were found compared with the same period 1 year earlier. After the LEC, case detection remained higher in the years 2000-2002 compared with the years preceding the LEC. More young (<15 years) paucibacillary (PB) cases were diagnosed during LEC activities with, surprisingly, equal percentage of disability grades. No gender imbalance was found in diagnosed LEC patients contrary to self-reporting patient groups. Comparing patients detected during a LEC in 1999 with the passive group of 1998 and 1999 showed a slight but statistically significant better treatment result for the passive group. The classification of leprosy (in favour of PB) and age (in favour of older age groups) were also determinants for favourable treatment outcomes. Volunteers had a significantly better result of treatment compared with trained nurses and regardless of detection method. LEC proved to be a useful addition to the National Leprosy and Tuberculosis Programme in Northern Mozambique. As a result, many new cases were diagnosed and put on treatment and their treatment results were very satisfactory. LEC had a lasting impact on case finding. Volunteers make a valuable contribution to leprosy control in Mozambique because they have consistently better treatment results compared with nurses.

Adolescent↗

PubMed2004

[Detection of KatG 315 gene mutation associated with isoniazid resistance in Mycobacterium tuberculosis by template-directed dye-terminator incorporation with fluorescence polarization detection technology].

OBJECTIVE: To study the relationship between KatG 315 mutation and isoniazid (INH) resistance in M. tuberculosis by template-directed dye-terminator incorporation with fluorescence polarization detection (TDI-FP), and to develop a new method that can detect INH-resistant M. tuberculosis precisely and quickly. METHODS: Isolates of M. tuberculosis resistant to INH from 82 tuberculosis patients were cultured on culture medium with different INH concentrations. DNA of all M. tuberculosis samples was extracted and amplification of 271 bp KatG gene fragment was carried out by polymerase chain reaction (PCR). After digestion of the excess primers and dNTPs in PCR products by clean-up reagents, template-directed dye-terminator incorporation reaction was performed, and the Acyclo-terminators labeled Rhodamine 110 (R110) or 6-carboxytetramethylrhodamine (TAMRA) were incorporated into the detection primers specifically. Then fluorescence polarization value was measured using Victor2 multi-label counter and the genotypes of the mutation site in 315 condon of KatG gene of all samples were investigated. RESULTS: There were 15 out of the 29 isolates of M. tuberculosis with high INH-resistance showed G-->C mutation in 315 condon of KatG gene, including 4 isolates with both mutated and non-mutated trains, the mutation frequency being 52%. In 32 isolates of M. tuberculosis with low INH-resistance, 15 were mixed infection, the mutation frequency being 47%. No mutation in 315 condon of KatG gene was found in 21 susceptible isolates of M. tuberculosis. CONCLUSIONS: The G-->C mutation in 315 condon of KatG gene was associated with INH-resistance of M. tuberculosis. TDI-FP technology was a reliable, easy to use and high-through method to detect mutation of KatG gene. It may be a useful technique for the diagnosis of INH-resistance in the future.

Antitubercular Agents↗

PubMed2004

Responding to detection of aerosolized Bacillus anthracis by autonomous detection systems in the workplace.

Autonomous detection systems (ADSs) are under development to detect agents of biologic and chemical terror in the environment. These systems will eventually be able to detect biologic and chemical hazards reliably and provide approximate real-time alerts that an agent is present. One type of ADS that tests specifically for Bacillus anthracis is being deployed in hundreds of postal distribution centers across the United States. Identification of aerosolized B. anthracis spores in an air sample can facilitate prompt on-site decontamination of workers and subsequent administration of postexposure prophylaxis to prevent inhalational anthrax. Every employer who deploys an ADS should develop detailed plans for responding to a positive signal. Responding to ADS detection of B. anthracis involves coordinating responses with community partners and should include drills and exercises with these partners. This report provides guidelines in the following six areas: 1) response and consequence management planning, including the minimum components of a facility response plan; 2) immediate response and evacuation; 3) decontamination of potentially exposed workers to remove spores from clothing and skin and prevent introduction of B. anthracis into the worker's home and conveyances; 4) laboratory confirmation of an ADS signal; 5) steps for evaluating potentially contaminated environments; and 6) postexposure prophylaxis and follow-up.

Air Microbiology↗

PubMed1989

[Detection and stimulus-detection electromyography (EMG), blink-reflex and trigeminal (V2 and V3) somatosensory evoked potentials (SSEP) in peripheral facial paralyses induced by cold. Importance of the systematic use of V SSEP in facial paralyses induced by cold].

Thirty-six patients afflicted with cold-induced peripheral facial paralysis were examined by classical detection and stimulus-detection E.M.G. methods (Blink Reflex) complemented by V (V2, V3) S.E.P. These examinations were carried out 4 to 7 weeks after the deficiency set in. Detection and stimulus-detection E.M.G. is the best method of confirming clinical diagnosis of peripheral facial paralysis. If there is the slightest sign of Charles Bell, the Blink-Reflex is an excellent confirmation test. S.E.P. of the V allows infra-clinical damage to the nerve to be discerned in 45% of the cases. The cause of this damage is a subject of debate.

Blinking↗

PubMed1989

Immunoassay detection of drugs in racing horses. XI. ELISA and RIA detection of fentanyl, alfentanil, sufentanil and carfentanil in equine blood and urine.

We have developed and evaluated a one step enzyme-linked immunosorbent assay (ELISA) test for sufentanil and a 125I radioimmunoassay test for alfentanil as part of a panel of pre- and post-race tests for narcotic analgesics in racing horses. Our sufentanil ELISA test detects sufentanil with an I-50 of about 0.5 ng/ml. The test is rapid and economical in that it can be read with an inexpensive spectrophotometer, or even by eye. The test readily detects the presence of sufentanil or its metabolites in equine blood and urine from 1 to 24 hours respectively after administration of therapeutic or sub-therapeutic doses of this drug. Our sufentanil assay also cross-reacts with fentanyl, the methylated analogs of fentanyl (designer fentanyls), and carfentanil and detected these drugs in urine for several hours after their administration to horses. It does not, however, cross-react significantly with alfentanil. We have also developed an 125I radioimmunoassay for alfentanil. This test allows detection of alfentanil in blood and urine of horses for up to 4 hours after administration of this drug. As such, these tests are capable of improving the quality and reducing the cost of pre-race and post-race testing for fentanyl, sufentanil, carfentanil and alfentanil and a number of their congeners in racing horses. Similarly, these tests are capable of screening for these drugs in human drug abuse monitoring.

Alfentanil↗

PubMed1987

Immunoassay detection of drugs in horses. I. Particle concentration fluoroimmunoassay detection of fentanyl and its congeners.

We investigated the use of particle concentration fluorescence immunoassay (PCFIA) as a technique for drug detection in racing horses. The test was constructed from an antiserum to a carboxyfentanyl-BSA conjugate and carboxyfentanyl linked to b-Phycoerythrin. Using these reagents and a PCFIA apparatus levels of fentanyl as low as 0.1 ng/ml could be detected by the assay. In addition, cross-reactivity studies on this assay showed that the anti-serum cross-reacted well with carfentanil, sufentanil and the methylated analogs of fentanyl. We therefore evaluated the ability of these agents to produce pharmacological effects in the horse and the ability of this test to detect pharmacologically significant doses of this drug in racing horses. All of these agents produced good locomotor responses in horses at doses of between 0.1 and 10 micrograms/kg. Of these agents, carfentanyl was the most potent followed by 3-methylfentanyl, sufentanyl, alpha-methylfentanyl, and fentanyl. Similarly, when these agents were administered to horses at doses sufficient to produce a pharmacological response, all produced sufficient inhibition of fluorescence in the PCFIA system to enable their detection in post-race urines from these horses. Since PCFIA is a much faster technique than radioimmunoassay, is of approximately similar sensitivity, and requires much less instrumentation we concluded that this technique holds considerable promise as an equine drug testing technique.

Animals↗

PubMed1993

A set of anti-crystallin monoclonal antibodies for detecting lens specificities: beta-crystallin as a specific marker for detecting lentoidogenesis in cultures of chicken lens epithelial cells.

Seven hybridoma lines which produced monoclonal antibodies against lens crystallins were established. They could detect alpha A-, alpha B-, gamma-, delta-, and several beta-crystallins of different species of animals with high avidities. Although immunohistological analysis of chicken and mouse lenses showed the typical distributions of each crystallin as have been reported so far, the ectopic expression of alpha B or delta-crystallin was observed in the brain or the kidney of chicken, respectively. Subsequently, crystallin production during the process of lentoidogenesis in cultures of chicken lens epithelial cells was examined with these antibodies. Western blot analysis revealed that beta-crystallins were not detected in cultured cells before lentoidogenesis, although all other crystallins were detected throughout the culture period. Immunostaining of cultures indicated clearly that expression of beta-crystallins was restricted to lentoid bodies. These data confirmed the lens fiber specificity of beta-crystallins as previously reported in the messenger RNA level. In addition, we found that small-size delta-crystallin (48 kDa) accumulated before the onset of lentoidogenesis. These results strongly suggest that the differentiated state of lens cells in vitro could be classified by examination of the expression pattern of crystallins. In addition, the anti-crystallin monoclonal antibodies produced in this study could be useful for detecting lens specificities.

Animals↗

PubMed1993

[Evaluation of usefulness of a new generation of tests for detection in humans of antibodies for 9,12 antigens of Salmonella. I. Occurrence and level of antibodies detected by DOT-ELISA, latex and passive hemagglutination tests].

The study was aimed at evaluation of usefulness of immunoenzymatic Dot-ELISA test and an own latex test (OL) for diagnosis of infections evoked by group D Salmonella in humans with application of passive hemagglutination test (OHS) as a relation test. Samples of blood donors, persons suspected of infection with group D Salmonella and of patients with acute gastroenteritis, were tested. In highest percentage of tested samples of serum derived from blood donors (84.5%), antibodies for 9, 12 antigen with Dot-ELISA were detected in immunoglobulin G class. In class IgM these antibodies were found in 46.5% of tested samples, whereas in IgA class only in 11.9% of samples. By application of passive hemagglutination, antibodies against 9, 12 antigen were detected in 56.8% of serum samples from blood donors and by application of a latex test in 8.7% of samples. Evaluation of antibody level of somatic antigen of group D Salmonella in healthy people formed a basis for determination for each of tests of a borderline serum titer accepted as diagnostically significant for specific antigenic stimulation. It permitted for analysis of variability of differences between the level of antibodies for 9, 12 antigen determined in blood donor serum and in patients from other two groups. By all three tests antibodies for 9, 12 antigen were detected significantly more frequently than in blood donors only in samples from patients suspected of Salmonella D infections. In highest percentage of samples (80.4%) these antibodies were detected by the Dot-ELISA test in IgM and IgG classes, slightly lower in OL (70.7% of samples) and in lowest in OHB (57.4% of samples). In samples of serum from patients with acute gastroenteritis, antibodies against 9, 12 antigen were found significantly more frequently than in blood donors only by the Dot-ELISA test in all classes of immunoglobulins (IgM-87.4%, IgA-56.2% and IgG-62.5% of serum samples).

Adult↗

PubMed1993

The role of antigen detection in pneumococcal carriers: a comparison between cultures and capsular antigen detection in upper respiratory tract secretions.

During the winter season upper respiratory tract secretions from 166 patients with stable chronic obstructive pulmonary disease (COPD) or asthma were simultaneously cultured for Streptococcus pneumoniae and tested for pneumococcal capsular antigen. Latex agglutination was employed to investigate the effect of pneumococcal carriership on pneumococcal capsular antigen detection in upper respiratory tract secretions. All specimens originating from the oropharynx, nasopharynx and saliva were both cultured and investigated in parallel for the presence of antigen. The recovery of pneumococci from the different areas was unequally distributed (oropharynx 29%, nasopharynx 8%, and saliva 16%), with the highest isolation rate from the oropharynx alone. Only 4 (3%) of the oropharyngeal swabs, 1 (1%) of the nasopharyngeal swabs and 14 (9%) of the saliva specimens yielded both pneumococcal antigen and a positive culture for S. pneumoniae. A further 9 (6%) of the oropharyngeal swabs, 5 (3%) of the nasopharyngeal swabs, and 50 (33%) of the saliva specimens were antigen positive only, with no pneumococci isolated on culture. It is speculated that these reactions were due to cross-reacting microorganisms (especially alpha-haemolytic streptococci) present in saliva and contaminating the oropharynx and the nasopharynx. Quantitative cultures of 9 oropharyngeal swabs yielded S. pneumoniae in concentrations too low to be detectable by latex agglutination. The study indicates that there is a poor relation between pneumococcal colonization and antigen detection in the oropharynx and nasopharynx. Antigen present in these secretions is probably not an important disrupting factor by contamination when detecting pneumococcal antigen in washed sputum. The false positive antigen results in saliva are probably due to cross-reactions with alpha-haemolytic streptococci.

Adult↗

PubMed1995

Detection of the heat-stable toxin coding gene (ST-gene) in enterotoxigenic Escherichia coli: development of a colour amplified PCR detection system.

Screening biological samples using the polymerase chain reaction (PCR) has obvious advantages compared with current molecular analytical methods based on gel electrophoresis and/or hybridisation, both of which are expensive and time-consuming, therefore the development of a PCR assay format that is applicable to large sample numbers and that can readily use equipment commonly found in diagnostic laboratories would be advantageous. This report describes the development of a colour amplified PCR detection system which is simple in design and could be universally applied to the detection of any DNA template. As an example, the system has been applied in the detection of the heat-stable toxin coding gene (ST-gene) from enterotoxigenic Escherichia coli (ETEC). The assay is sensitive, detecting 10 fg of a purified DNA template and 270 cfu of an ST-gene-positive ETEC strain.

Bacterial Toxins↗

PubMed1998

Use of nonbreakpoint DNA probes to detect the t(X;18) in interphase cells from synovial sarcoma: implications for detection of diagnostic tumor translocations.

Fluorescence in situ hybridization studies using non-breakpoint DNA probes were performed to detect the X;18 translocation on 4-microm sections of synovial sarcoma from paraffin blocks. This was done by using commercially available, large target unique sequence DNA probes for regions of the X chromosome short-arm and the 18 chromosome long-arm together with centromere probes for the alternate chromosomes. We determined that such probe combinations could detect the presence of the diagnostic X;18 translocation in interphase cells. Spatial association of dual color signals from the X centromere and the 18 unique sequence probe, as well as between an 18 centromere and the X unique sequence probe, was seen in a significantly higher percentage of synovial sarcoma cells (81.1% +/- 7.7%, confidence interval 95%) than in control nonsynovial soft tissue sarcomas (14.7% +/- 8.3%) and control peripheral blood lymphocytes (5.6% +/- 0.6%). The observed spatial association supports the use of this strategy to detect the X;18 translocation in synovial sarcoma and suggests that this technique could be applied in the diagnosis of other types of tumors with characteristic translocations when histopathological findings are inconclusive. This study is the first report describing the use of nonbreakpoint unique sequence probes for detecting translocations in tumors on paraffin-embedded slides.

Chromosomes, Human, Pair 18↗

PubMedDate not supplied

Determination of the Fusarium mycotoxins nivalenol, deoxynivalenol, 3-acetyldeoxynivalenol, and 15-O-acetyl-4-deoxynivalenol in contaminated whole wheat flour by liquid chromatography with diode array detection and gas chromatography with electron capture detection.

A rapid and sensitive method was developed for simultaneous detection of nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-A-DON), and 15-O-acetyl-4-deoxynivalenol (15-A-DON) in wheat flour. Samples were extracted with acetonitrile-water (84 + 16), and the extract was filtered and purified by a column containing a combination of charcoal, celite, and other adsorbents. For screening analysis, the column eluate was only extracted with ethyl acetate. After evaporation of the solvent, the dried residue was redissolved in acetonitrile-water (2 + 8) and then analyzed by reversed-phase liquid chromatography (LC) with diode array detection. Recoveries of NIV, DON, 3-A-DON, and 15-A-DON from whole wheat flour spiked at 2 levels were 49-55, 92-97, 98-100, and 100-105%, respectively. To quantitate mycotoxin amounts lower than 1 ppm, purified column extracts were evaporated to dryness, derivatized with heptafluorobutyric anhydride, and analyzed by gas chromatography with electron capture detection (GC-ECD). Average recoveries of NIV, DON, 3-A-DON, and 15-A-DON from whole wheat flour spiked at 2 levels, were 45-52, 91-103, 81-85, and 84-92%, respectively. GC-ECD detection limits for all mycotoxins tested at a signal-to-noise ratio of 4:1 were < 30 ng/g. Results of GC-ECD analysis for whole wheat flour samples spiked with mycotoxins at 3 and 10 ppm compared well with results (2.8 and 9.9 ppm) for the same samples analyzed by LC.

Chromatography, Gas↗

PubMed1998

Development of a dual-probe detection system for positron emission radiotracer detection.

BACKGROUND: Positron emission radiotracers are very useful in biochemical and pharmacological research. The purpose of this work was to develop and build a simple and inexpensive dual-probe detector system (DPDS) for detecting the activity of positron emission radiotracers. MATERIALS AND METHODS: The design of the DPDS was based on the coincident detection of two 511 KeV annihilation gamma-rays, which determined the positron activity in the body. A pair of sodium iodide (NaI) scintillators coupled to a photomultiplier tube (PMT) were positioned face-to-face as in a dual-probe system. The signals from each probe were then sent to a preamplifier, a linear amplifier, a single channel analyzer (SCA), and the primary and secondary coincidence units, respectively, to determine the number of total coincidence events and random events. Validation of basic characteristics, including stability, sensitivity, linearity and geometric counting efficiency, were tested. RESULTS: The sensitivity and linearity of the DPDS worked well in detecting radioactivity within 100 microCi. The DPDS was very stable in continuous counting for more than 2 hours. The geometric counting efficiency changed less than 5% when the source was placed 2 cm from the central coincidence line. CONCLUSION: This DPDS is a promising tool for positron emission radiotracer detection. It may be helpful in future in both clinical and basic biomedical research, such as neuroreceptor occupancy or glucose metabolic studies. Eventually, we will be able to use the DPDS in the human or animal body for evaluating position emission radiotracer metabolism and distribution.

Humans↗

PubMed2006

Factors influencing F-wave latency detection of lumbosacral root lesions using a detection theory based model.

OBJECTIVE: To evaluate the F-wave dilution hypothesis; which implies that absolute F-wave latencies obscure the much smaller delay associated with slow intra-lesion conduction, such is caused by nerve root compression in lumbosacral radiculopathy. A corollary objective is to determine how F-wave measurement and pathological factors influence diagnostic accuracy. METHODS: An analytical model is developed based on signal detection theory and a number of simplifying assumptions. Diagnostic accuracy, quantified by the area under the receiver operating characteristic (ROC) curve, is determined for various model realizations derived from the clinical and experimental neurophysiology literature. A preliminary experimental validation of model predictions is also performed. RESULTS: Absolute F-wave latency does not influence the accuracy of focal lesion detection. F-wave latency variance and lesion pathology are the determinant factors. F-wave latencies and distal latencies are estimated to have qualitatively similar detection characteristics, although distal latencies have quantitatively better diagnostic efficacy for comparable focal pathology. Preliminary experimental results support the modeled dependence of diagnostic accuracy on latency variance and lesion severity. CONCLUSIONS: Absolute F-wave latency does not dilute slow conduction within focal lesions, such as in lumbosacral radiculopathy. The dominant measurement factor is F-wave latency variance. SIGNIFICANCE: To maximize the diagnostic utility of F-wave latencies, focus must be placed on reducing latency variance, such as through correction for demographic covariates. This model calls into question the F-wave dilution hypothesis.

Adolescent↗

PubMed2006

Effective cervical neoplasia detection with a novel optical detection system: a randomized trial.

OBJECTIVE: To assess whether the use of a novel optical detection system (ODS) as an adjunct to colposcopy increases the detection of biopsy-confirmed CIN 2,3. METHODS: This is a multicenter two-arm randomized trial comparing colposcopy alone with colposcopy plus a pre-commercial ODS system that utilizes fluorescence, white light tissue reflectance, and cervical video imaging. Patients were recruited from 13 colposcopy clinics in a variety of practice settings. 2299 women referred for the evaluation of an abnormal cervical cytology were randomized with stratification by cytology; subsequently 113 women were excluded for a variety of reasons. The main study outcomes were differences in true-positive rates (CIN 2,3 and cancer identified) and false-positive rates between the study arms. RESULTS: The true-positive (TP) rates were 14.4% vs. 11.4% (p=0.035, one-sided) for the combined colposcopy and ODS arm compared to colposcopy-only arm, respectively, in women with either an atypical squamous cell (ASC) or low-grade squamous intraepithelial lesion (LSIL) cytology result. TP rates were similar between the two arms among women referred for the evaluation of HSIL. The 26.5% gain in true-positives observed with the use of ODS and colposcopy among women referred for an ASC or LSIL cytology was achieved with only a fractional increase in number of biopsies obtained per patient (0.30) and a modest increase in false-positive rate (4%). In the combined colposcopy and ODS arm among women with ASC or LSIL, the PPV of biopsies indicated by ODS was 15.0% and the PPV of biopsies indicated by colposcopy was 15.2%. Joint hypothesis testing indicates that ODS and colposcopy provides benefit compared to colposcopy alone among women with ASC or LSIL. CONCLUSIONS: Combining ODS with colposcopy provides a clinically meaningful increase in the detection of CIN 2,3 in women referred for the evaluation of mildly abnormal cytology results.

Adult↗

PubMed2004

Detecting true lies: police officers' ability to detect suspects' lies.

Ninety-nine police officers, not identified in previous research as belonging to groups that are superior in lie detection, attempted to detect truths and lies told by suspects during their videotaped police interviews. Accuracy rates were higher than those typically found in deception research and reached levels similar to those obtained by specialized lie detectors in previous research. Accuracy was positively correlated with perceived experience in interviewing suspects and with mentioning cues to detecting deceit that relate to a suspect's story. Accuracy was negatively correlated with popular stereotypical cues such as gaze aversion and fidgeting. As in previous research, accuracy and confidence were not significantly correlated, but the level of confidence was dependent on whether officers judged actual truths or actual lies and on the method by which confidence was measured.

Adult↗

PubMed2004

Signal detection theory applied to three visual search tasks--identification, yes/no detection and localization.

Adding distracters to a display impairs performance on visual tasks (i.e. the set-size effect). While keeping the display characteristics constant, we investigated this effect in three tasks: 2 target identification, yes-no detection with 2 targets, and 8-alternative localization. A Signal Detection Theory (SDT) model, tailored for each task, accounts for the set-size effects observed in identification and localization tasks, and slightly under-predicts the set-size effect in a detection task. Given that sensitivity varies as a function of spatial frequency (SF), we measured performance in each of these three tasks in neutral and peripheral precue conditions for each of six spatial frequencies (0.5-12 cpd). For all spatial frequencies tested, performance on the three tasks decreased as set size increased in the neutral precue condition, and the peripheral precue reduced the effect. Larger set-size effects were observed at low SFs in the identification and localization tasks. This effect can be described using the SDT model, but was not predicted by it. For each of these tasks we also established the extent to which covert attention modulates performance across a range of set sizes. A peripheral precue substantially diminished the set-size effect and improved performance, even at set size 1. These results provide support for distracter exclusion, and suggest that signal enhancement may also be a mechanism by which covert attention can impose its effect.

Attention↗

PubMed2000

Modification of screening immunoassays to detect sub-threshold concentrations of cocaine, cannabinoids, and opiates in urine: use for detecting maternal and neonatal drug exposures.

Testing for drugs of abuse in urine is commonplace in emergency departments and neonatal units. However, the clinical sensitivity of immunochemical screening methods is limited by the threshold concentrations used to distinguish between positive and negative specimens. Immunochemical screening methods for cocaine metabolite (benzoylecgonine), cannabinoids, and opiates in urine were recalibrated to detect drugs at lower threshold concentrations. The precision and linearity of the signals at the modified thresholds were verified by diluting drug-positive urine specimens to concentrations below the conventional cutoff concentration and measuring the rate signals in triplicate. To assess the clinical performance of the modified methods, specimens that tested negative using the unmodified assays were re-screened at the lower threshold, and specimens that re-screened positive were submitted for gas chromatographic/mass spectrometric (GC/MS) confirmation. Reproducibility of sub-threshold measurements was comparable to the unmodified assays, and rate separations between successive dilutions were sufficient to give semi-quantitative results. Using the lower thresholds, drugs were detected in 4-5% of the subjects that had screened negative at the conventional threshold concentration. GC/MS analysis confirmed the presence of cannabinoids and cocaine metabolite in 74% and 84%, respectively, of urine specimens that re-screened positive. Morphine, codeine, hydromorphone, or hydrocodone was detected by GC/MS analysis in 31% of opiate-positive re-screens.

Adult↗