Comparison of CAPTIA syphilis G enzyme immunoassay with rapid plasma reagin test for detection of syphilis

The CAPTIA Syphilis G enzyme-linked immunosorbent assay compared favorably with the rapid plasma reagin test when used to screen for syphilis in a low-risk population. The sensitivity and specificity of the CAPTIA Syphilis G test were 100 and 97.8%, respectively, for 646 routine specimens and 100 and 99.2%, respectively, for 265 specimens from obstetrics patients. Overall, for 911 specimens, the CAPTIA Syphilis G test showed a sensitivity of 100%, a specificity of 98.2%, and positive and negative predictive values of 78.9 and 100%, respectively. For the same population, the rapid plasma reagin test showed a sensitivity and a specificity of 96.4 and 97.5%, respectively, and positive and negative predictive values of 72 and 99.8%, respectively.     

Comparison of polymerase chain reaction with culture and enzyme immunoassay for diagnosis of pertussis

The risk for human infection with Lyme disease appears linked to the abundance of infected vector ticks, principally Ixodes dammini Spielman, Clifford, Piesman & Corwin, in the eastern United States. Habitat destruction by burning, although not well studied, has long been considered as an effective alternative to synthetic insecticides as a means of reducing tick populations. We evaluated the effect of a single spring burning of the woodland understory on the transmission risk of Lyme disease spirochetes (Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner) on Shelter Island, Long Island, NY. Following a burn in early April 1991, the abundance of nymphal I. dammini was 49% lower in the burned portion of a woodlot compared with the unburned portion. However, risk of encountering nymphs infected with B. burgdorferi remained similar in both burned and unburned woods. It is suggested that burning vegetation may disproportionately kill deer-derived rather than rodent-derived nymphs, significantly reducing tick abundance without affecting transmission risk.     

Evaluation of an enzyme immunoassay kit for the detection of Clostridium difficile enterotoxin

The Premier Clostridium difficile toxin A enzyme immunoassay (EIA) kit was evaluated for the detection of C. difficile enterotoxin in fecal samples. A total of 314 samples was tested by culture, cytotoxin detection and EIA kit. Compared to a combined culture/cytotoxin result the Premier EIA kit had a sensitivity of 88.3%, a specificity of 100%, a predictive value positive of 100% and a predictive value negative of 87.4%. Test results were available within 3 hrs providing a rapid and reliable means of detecting C. difficile enterotoxin.     

Evaluation of an antigen-capture enzyme immunoassay for detection of Entamoeba histolytica in stool samples

In order to identify the prevalence of Entamoeba histolytica in tourists with diarrhoea returning from countries of the developing world, sensitivity and specificity of a commercially available enzyme immunoassay (EIA) kit for the detection of Entamoeba histolytica coproantigen in stool were evaluated. Five hundred seventy-seven specimens from 469 patients were examined by microscopy and EIA. Sixty-two specimens from 49 patients were considered positive for Entamoeba histolytica. Compared with microscopic examination of stool samples, the EIA was found to be slightly more sensitive (90.3% vs. 87.1%) and was 97.7% specific for Entamoeba histolytica.     

Preparation of respiratory syncytial virus subgroup A and B antigens for enzyme immunoassay antibody detection

A simplified method was described for purification of respiratory syncytial virus (RSV) subgroup A and B aimed to be used as antigens in enzyme immunoassay (EIA). The titer of each RSV subgroup and the amount of protein was determined from the visible band in 45% sucrose gradient. The quality of prepared RSV subgroup antigens for EIA was described in terms of the achievable final titer, the amount of protein, and EIA criss-cross titration. The RSV subgroup A and B antigens, diluted as 1:100 (low opalescent band in 45% sucrose layer) or 1:800 (high opalescent band in 45% sucrose layer) produced a positive reaction in EIA criss-cross titration with IgG antibodies from the patient's serum (convalescent phase) diluted as 1:25,600 (for RSV A) and 1:6,400 (for RSV B). This method offers shorter and more simplified steps of viral antigen purification, and provides acceptable quantity and quality of viral antigens appropriate for use in EIA.     

Competitive enzyme immunoassay for bovine growth hormone

We developed an enzyme immunoassay (EIA) for bovine GH (bGH) which is based on indirect competitive immunoassay in culture medium from a bovine pituitary cell culture. 40 microliters cell culture samples (or bGH standard) and bGH antibody (rabbit anti-bGH) were added to the 96 well microplate coated with secondary antibody (Goat anti-rabbit IgG), and incubated for 24 h at 37 degrees C. Biotin-label bGH was added and incubated further for 24 h at 37 degrees C, and biotinylated bGH was linked with streptoavidin-peroxidase. Substrates for peroxidase were added to the plate and incubated for 1 h at 4 degrees C. The enzyme reaction was stopped with 4N H2SO4, and the absorbency at 450 nm was measured with an ELISA Reader. The coefficients of intra-assay and inter-assay variations were 4.13 approximately 7.59% and 3.71 approximately 8.27%, respectively. The regression equation and correlation coefficients with the radioimmunoassay (RIA) were y(RIA) = 1.9986 x (EIA) - 1.3921 and 0.9701 (n = 27), respectively. Collectively, the present assay provides a reliable alternative to RIA and offers the major advantage of eliminating radioactive reagents and counting equipment.     

A solid-phase enzyme immunoassay for serum ferritin

We describe an enzyme immunoassay for human serum ferritin in which antibody adsorbed on polystyrene tubes is used. Adsorbed gamma-globulins against human ferritin were first allowed to react with ferritin and a second antiferritin antibody, labeled with alkaline phosphatase, was added. The amount of bound enzyme/antibody conjugate was proportional to the ferritin titer in the assay. This method offers stable reagents that can be kept for many months at 4 degrees C. The average values for ferritin in normal men and women were, respectively, 58 and 43 microgram/liter. The lowest detectable concentration was 5 microgram/liter.     

Critical examination of an enzyme immunoassay for detection of positive IgM antibodies against toxoplasma in newborns

The Toxonostika IgM test, which has been examined in this study, is a modified antibody capture test (7). Evaluation with sera from newborns revealed that, like in the ELISA tested in 1988, doubtful or false positive results were obtained in 10% of the cases (6). Therefore, a positive toxoplasmosis IgM result in newborn sera should always be retested with another test system.     

Dipstick enzyme immunoassay for rinderpest antibody in cattle

A dipstick enzyme immunoassay (ELISA) has been standardized for the detection of rinderpest antibodies. One hundred and thirty bovine serum samples were analysed by the dipstick ELISA method and the results compared with the conventional plate ELISA method. The sensitivity was found to be similar in both methods. The dipstick ELISA does not require expensive micro-plates and an ELISA reader, and is recommended for use in field laboratories where the qualitative detection of rinderpest antibodies is required.     

Highly specific enzyme immunoassay for human chorionic gonadotropin

A highly specific enzyme immunoassay for determining hCG was established by using beta-D-galactosidase as label. In order to increase the specificity of the assay, an antiserum against whole hCG was purified on a column of hCG beta carboxyl-terminal peptide (residues 123-145) covalently linked to Sepharose 4B. The antibody (N101S) thus prepared showed a weak cross-reactivity with human LH in an assay using hCG-enzyme conjugate, but the slight cross-reactivity was virtually avoided when an hCG beta carboxyl-terminal peptide was used as a peptide in the enzyme conjugate. N101S antibody was compared with antiserum (B1B) directed against a carboxyl-terminal peptide (123-145). In hCG measurement N101S gave about 30 times higher sensitivity than B1B, although the former antibody was less sensitive to carboxyl-terminal peptides of hCG beta. The enzyme immunoassay using a combination of N101S antibody and a carboxyl-terminal peptide (130-145)-enzyme conjugate was able to detect as little as 0.25 mIU of hCG without the interference of LH. The performance and validity of this assay were comparable to those of conventional radioimmunoassay.     

Novel enzyme immunoassay and optimized DNA extraction for the detection of polymerase-chain-reaction-amplified viral DNA from paraffin-embedded tissue

Four different DNA extraction methods were compared to determine their ability to provide DNA for amplification of viral sequences from paraffin-embedded human tissue samples by polymerase chain reaction (PCR). The suitability of extraction methods was assessed using parameters like DNA yield, length of recovered DNA fragments, and duration. Furthermore, the efficiency of amplifying a human single-copy gene, the beta-globin gene, from DNA samples was tested. The best preservation of DNA molecules could be achieved by binding the DNA onto a silica column before further purification. Viral DNA sequences could be amplified by PCR in DNA extracted from routinely processed paraffin blocks from cases with clinically or morphologically suspected cytomegalovirus or Epstein-Barr virus infections. The PCR products were specified by a novel liquid hybridization assay called PCR-enzyme-linked immunosorbent assay. Using this assay, the time-consuming Southern hybridization could be replaced and the time requirement for the detection of PCR products could be reduced from 1 day to 4 hours. The assay system described here represents a reliable, sensitive, and specific method for the detection of viral DNA from paraffin-embedded tissue samples.     

A novel rapid enzyme immunoassay (Fluorophos BetaScreen) for detection of beta-lactam residues in ex-farm raw milk

A novel, qualitative enzyme immunoassay based on fluorescence detection for determination of beta-lactam antibiotics in raw, commingled milk (Fluorophos BetaScreen E. U. test) was evaluated. A dose-response profile for penicillin G was constructed by analysis of spiked milk samples. The limit of detection, defined as the concentration of penicillin G that resulted in 95% of the samples being evaluated as positive, was 1.8 micrograms/kg. The repeatability of the assay was very high both within and between the three participating milk quality testing laboratories. In total 5,061 randomly selected tanker milk samples were analyzed with the BetaScreen test and compared with the Delvotest SP. The agreement between the two tests was 99.7%. Probably due to a higher sensitivity to penicillin G, the BetaScreen test detected almost twice as many suspect positive tanker milk samples (0.45%) as the Delvotest SP (0.26%).     

Polymacron enzyme immunoassay system for detection of naturally contaminating Salmonella in foods, feeds, and environmental samples

A simple dot blot enzyme immunoassay was developed to screen enrichment broth cultures for the presence of Salmonella. This unique system utilizes macroporous polyester cloth (Polymacron) with an inexpensive hemoglobin coating to provide a high-affinity adsorbent for lipopolysaccharide (LPS) antigens in test samples. Bound LPS antigens are then detected using a monoclonal antibody conjugate recognizing a core oligosaccharide epitope common to all salmonellae frequently found in foods and related samples. The entire test (not including enrichment culture) could be completed in less than 1 h. The performance of this assay was evaluated in the analysis of enrichment broth cultures from a variety of egg and dairy products, chicken carcasses, animal feeds, and food-processing plant environmental samples for the presence of Salmonella.     

Application of enzyme immunoassay for postchemotherapy evaluation of human strongyloidiasis

Primer extension preamplification (PEP) increases the scope and capacity of single cell genetic diagnosis by generating sufficient template to perform multiple subsequent DNA analyses using the polymerase chain reaction. We report the simultaneous analysis of single cells at five commonly deleted dystrophin exons and at the ZFX/ZFY loci. Ninety three percent of PEP reactions with single amniocytes, chorionic villus cells and blastomeres were successful, and a blinded analysis of single lymphoblasts from affected males resulted in 93% diagnostic accuracy, demonstrating its applicability in preimplantation prevention of Duchenne muscular dystrophy. Transfer of unaffected male embryos and improved diagnostic reliability are achieved with the ability to perform replicate multilocus analyses from the same blastomere.     

Q390高强抗震钢板残余应力检测方法对比及分析

利用盲孔法、X-Ray法、中子衍射法和超声法对Q390高强抗震板及U形弯曲件进行残余应力检测,并对这4种方法测试得到的应力结果进行分析研究。结果表明,以上4种检测方法均要考虑其特定的检测应用范围,X-Ray法针对钢板表面下微米级深度的微米级晶格尺度范围局部点应力进行检测,中子衍射法可在毫米级尺度局部区域进行应力检测,盲孔法反映的是因毫米尺度钻孔导致的钢板表面孔周边的应力变化,超声法则可以通过连续扫描检测整个钢板残余应力的宏观分布变化。因此,对于工业钢板,超声法测试残余应力更加科学、合理、准确。同时,通过U形试样建立稳定的应力应变场,利用超声设备使用不同参考态对Q390高强抗震板弯曲件及退火弯曲件进行测试,结果表明,测试参考态的选取对应力测试结果影响很大,材料各向异性的影响对应力测试结果不可忽视。     

Mass-sensing, multianalyte microarray immunoassay with imaging detection

Miniaturization of ligand binding assays may reduce costs by decreasing reagent consumption, but it is less apparent that miniaturized assays can simultaneously exceed the sensitivity of macroscopic techniques by analyte "harvesting" to exploit the total analyte mass available in a sample. Capture reagents (avidin or antibodies) immobilized in 200-microm diameter zones are shown to substantially deplete analyte from a liquid sample during a 1-3-h incubation, and the assays that result sense the total analyte mass in a sample rather than its concentration. Detection of as few as 10(5) molecules of analyte per zone is possible by fluorescence imaging in situ on the solid phase using a near-infrared dye label. Single and multianalyte mass-sensing sandwich array assays of the IgG subclasses show the sensitivity and specificity of ELISA methods but use less than 1/100 the capture antibody required by the 96-well plate format.     

A monoclonal inhibition enzyme immunoassay for detection of antibodies against hepatitis B core antigen: confirmation of an immunodominant epitope

We examined the situational antecedents of binge eating episodes and tested for consistency in the antecedents. We evaluated the antecedents of two successive binges via structured interviews with 50 normal-weight nonpurging females who regularly binge. Cluster analysis yielded two categories of binge-promoting situations: solitary negative affect situations and social eating situations. When this empirically derived classification of binge situations was used, the two successively occurring binges did not systematically fall into the same cluster. Consistency on other measures was also modest. Implications of these findings for conceptual models of binge eating and treatment, including the prospect of individually tailored interventions, are discussed.     

Evaluation of a new enzyme immunoassay for Clostridium difficile toxin A

AIM: To evaluate a new enzyme immunoassay (EIA) method for detection of Clostridium difficile toxin by comparing it to cytotoxicity assay. To investigate the nature of false negative and false positive EIA results by evaluating clinical and therapeutic parameters. METHODS: 737 consecutive diarrhoeal specimens collected from patients clinically suspected of having C difficile colitis were tested for the presence of C difficile toxin by EIA for toxin A and by cytotoxicity assay. Clinical data were evaluated in all cases positive by either method. RESULTS: With the cytotoxicity assay as a gold standard, the specificity of EIA for toxin detection was 99.3% and the sensitivity was 62.2%. No false negative EIA specimens were obtained from patients already being treated for C difficile colitis. Among patients with cytotoxicity positive specimens, those with EIA positive samples had no clinical features distinguishing them from patients with EIA negative samples. CONCLUSIONS: Although specific, the new EIA method directed against toxin A lacks sensitivity compared to cytotoxicity. False negative EIA tests are not associated with concurrent treatment for C difficile colitis nor with any specific clinical features examined in our study.