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PubMed1991

Urine protein determination in dogs and cats: comparison of dipstick and sulfasalicylic acid procedures.

Protein levels in urine specimens from 91 dogs and 65 cats were evaluated by sulfasalicylic acid precipitation (SSA) and dipstick methods. The dipstick frequently yielded reactions for protein that were greater than the level of protein indicated by SSA (i.e., false positive reactions), although no false negative reactions for protein were noted. All urine specimens with protein levels equal to or greater than 100 mg/dl by SSA had dipstick results of 3 +. Results of this study suggest that dipstick analysis for urine protein is an adequate screening procedure for the selection of urines for quantitative analysis of protein and creatinine to assess proteinuria.

Journal Article↗
PubMed1974

Use of immunoperoxidase for the rapid identification of human myxoviruses and paramyxoviruses in tissue culture.

The immunoperoxidase method, using commercially available antisera, was compared with standard virological methods for the identification and typing of 77 isolates of human myxoviruses and paramyxoviruses. Results of typing using neutralization tests and the immunoperoxidase technique were identical for 76 of the 77 isolates. With the immunoperoxidase method there was one false negative reaction, but no false positive reactions. Cross-reactivity between influenza A (soluble) and A(2)/HK antisera with influenza A isolates was noted, but did not interfere with the interpretation of results. It is concluded that the immunoperoxidase method is ideally suited for the rapid identification and typing of common human respiratory viruses on a routine basis. It offers a number of decided advantages over both immunofluorescence and standard virological methods.

Antigens, Bacterial↗
PubMed1994

Accumulation of 99mTc-glutathione in head and neck tumors.

Glutathione labelled with 99mTc was used to study blood clearance and normal distribution in 3 healthy volunteers and in 10 patients with biopsy-proven tumors in the head and neck region. Static scintigrams were obtained at 1, 3, 6, and 24 h. ROIs over tumors and normal soft tissues were compared to obtain T/N ratios. In normal subjects blood clearance reached a plateau at 6 h; no radio-activity accumulation in the head and neck region was observed. Only the cardiac blood pool, the liver, the kidneys and the urinary bladder were evident. Excretion was via the kidneys. Malignant tumors and metastases were well visualized in 7 patients (true-positive), starting at 1 h. The mean T/N ratio was 2.69 +/- 0.77. The best images were obtained at 3-6 h. 1 false-positive (granulamatous reaction), 1 false-negative (malignant epithelial tumor in the radix of tongue) and 1 true-negative (angiofibroma) results were obtained. 99mTc-GSH is a potential radiopharmaceutical for the scintigraphic visualization of head and neck tumors. Further clinical studies are warranted to show its sensitivity and accuracy.

Adult↗
PubMed1981

Comparative efficiency of brilliant green, bismuth sulfite, Salmonella-Shigella, hektoen enteric, and xylose lysine desoxycholate agars for the recovery of Salmonella from foods: collaborative study.

The relative efficiency of brilliant green (BG), bismuth sulfite (BS), Salmonella-Shigella (SS), xylose lysine desoxycholate (XLD), and Hektoen enteric (HE) agars for the recovery of Salmonella from 5 foods was collaboratively studied in 11 laboratories. The analytical efficiency of various paired combinations of the 5 agars was statistically compared according to 3 parameters: (1) productivity or recovery of Salmonella, (2) rate of enumeration of cultures that were false positive for Salmonella, and (3) rate of enumeration of false-negative reactions. In descending order of productivity, the sequential ranking was BS, XLD, HE, BG, and SS agars. In ascending order, the rates of false-positive reactions based on a statistical analysis of paired agar combinations was HE, BS, BG and XLD (tie), and SS agars. Analogously, in ascending order, the sequence of false-negative reaction rates was BS, XLD, HE, BG, and SS agars. The combination of BS, XLD, and HE agars is more efficient for recovery of Salmonella from foods than is the present official combination of BG, BS, and SS agars. The revision of official final action method 46.054 to replace the combination of BG, BS, and SS agars with a combination of BS, XLD, and HE agars has been adopted official first action.

Agar↗
PubMed1976

Reliability of chemical tests for fecal occult blood in hospitalized patients.

In 39 hospitalized patients with suspected gastrointestinal bleeding and given intravenous 51Cr-labeled red cells, reactions of three chemical spot tests for fecal occult blood were compared with the "true" blood loss as determined by stool radioassay. Guaiac reagent and orthotolidine (Hematest) tablets were extremely sensitive, but yielded false-positive reaction rates of 72% and 76%, respectively on the 240 stool specimens compared. A modified guaiac test (Hemoccult) exhibited a false positive rate of 12%. Of the 27 patients entering the study due to positive guaiac or Hematest screening tests, 17 (63%) were not bleeding. Hemoccult, approximately 1/4 as sensitive as guaiac and Hematest, could miss lesions with low rates of bleeding unless multiple stools were tested. While barium had no effect, iron therapy or laxatives tended to lower both false-positive and false-negative reactions for all reagents. A positive Hemoccult test usually indicated significant gastrointestinal bleeding and would appear to be the test of choice provided at least 3 stools are tested to minimize false-negative results.

Barium Sulfate↗
PubMed1987

[Methodologic problems in the detection of indole formation by anaerobic pathogens].

The demonstration of indole formation is of great value for the identification of pathogenic anaerobes. A reduction of the pH to values below the critical range of 5.1-5.3 in complex media 5.5 in simple testing substrates, respectively, which is caused by the presence of fermentable carbohydrates and will result in false-negative reactions. For this reason, the indol test should be performed with an adequate buffer capacity and an addition of fermentable carbohydrates should be avoided. Strains showing a false-negative reaction in the spot indole test can be reliably accounted for by means of the rapid test in buffered tryptophan solution described here without having to use additional anaerobic culture methods.

Bacteriological Techniques↗
PubMed2001

Comparison of different enrichment broths and background flora for detection of heat-injured Listeria monocytogenes in whole milk.

Various primary enrichment broths, including University of Vermont medium (UVM), Listeria enrichment broth (LEB), modified LEB, and aerobic and anaerobic L-PALCAMY, were compared with aerobic and anaerobic Pennsylvania State University (PSU) broths for the detection of severely heat-injured (62.8 degrees C for 5, 10, or 15 min; no colony appearance after heat injury on aerobic Trypticase soy agar containing 0.6% yeast extract and modified Oxford medium) Listeria monocytogenes Scott A. Anaerobic conditions were produced by adding L-cysteine and then purging the headspace with N2. The effect of uninjured background flora (10(3) CFU/ml of Enterococcus faecium) on frequency of detection was examined. Anaerobic PSU broth resulted in the lowest false-positive rate and the highest frequency of detection of severely heat-injured L. monocytogenes compared with UVM, LEB, and modified LEB (P < 0.05). The presence of E. faecium significantly enhanced the detection of heat-injured (10 min at 62.8 degrees C) L. monocytogenes in aerobic and anaerobic PSU and aerobic and anaerobic L-PALCAMY broths (P < 0.05). The highest concentration of uninjured E. faecium (>10(6) CFU/ml) inhibited the detection of heat-injured L. monocytogenes (P < 0.05). A heat-resistant, LiCl-tolerant Lactobacillus isolate from raw milk increased the rate of both false-positive and false-negative reactions.

Aerobiosis↗
PubMed1976

The value of the skin test and complement fixation test in the diagnosis of chronic pulmonary histoplasmosis.

Histoplasmin skin test results in patients with chronic pulmonary histoplasmosis from Missouri and Texas were compared to results in a previous study of U.S. Navy recruits. When consideration was given to geographic areas from which persons from each group were admitted to the study, it was found that the recruits were as likely to have a positive skin test as were those with the disease. In a similar manner, the Texas histoplasmosis patients were compared to groups of patients from that state with chronic obstructive pulmonary disease and with pulmonary tuberculosis. Again, no significant differences were found. It was concluded that the histoplasmin skin test is not of value in the diagnosis of chronic pulmonary histoplasmosis. Histoplasmosis complement fixation test data from the chronic pulmonary histoplasmosis group were compared to data from the chronic obstructive pulmonary disease and pulmonary tuberculosis groups. The usefulness of the complement fixation test in chronic pulmonary histoplasmosis is limited, as with any test, by false-positive and false-negative reactions. A decision theory method was used to define the limits of usefulness.

Chronic Disease↗
PubMed1995

Occupational allergic contact dermatitis from ethyl cyanoacrylate.

Glues based on cyanoacrylates are widely used as contact adhesives for metal, glass, rubber, plastics and textiles, as well for biological materials, including binding tissues and sealing wounds in surgery. In this paper, an apprentice cobbler with an occupational allergic contact dermatitis from an ethyl cyanoacrylate glue, in which the major monomer was shown to be the sensitizer, is reported. Initial patch testing with the cyanoacrylate glue dissolved in acetone with the Finn Chamber (aluminium) technique yielded false-negative reactions. Positive test reactions were obtained with the same preparations using Van der Bend chambers. With petrolatum as vehicle for the glue, there was no difference between Finn Chamber technique and Van der Bend chamber technique. The role of aluminium in the false-negative reactions is discussed.

Abdomen↗
PubMedDate not supplied

[[Evaluation of various methods of studying fecal occult blood].

Occult blood testing for detection of asymptomatic colorectal cancer is an old concept. The authors review the literature about the screening value of current tests. Among the chemical tests, Hemoccult is the most popular and the best studied. Sensitivity and specificity are moderate. False negative reactions are due either to the test itself (high level of sensitivity, loss of reactivity) or to the tumour (intermittent or insufficient bleeding, localization etc...). False positive reactions are due to the interference of a high peroxidase diet. The Hemoccult test is nevertheless interesting because it is simple, cheap and well accepted. Detected cancers tend to be at a relatively early stage: 60 to 80% of Dukes A or B. New methods--Hemoquant and immunochemical methods--are being developed. Their high degree of sensitivity and specificity for human hemoglobin makes them too complex and too costly. Whatever the efficacity of a test to detect occult blood may be, we must know whether the screening of an asymptomatic population could decrease the mortality rate of colorectal cancer, before using it on a large scale. Only long-term controlled trials can give us an answer in the future.

Colorectal Neoplasms↗
PubMed1992

Comparative study of TRUE Test and Finn Chamber patch test techniques in Singapore.

This is a report on a comparative study of the reactivity of TRUE Test and Finn Chamber patch test techniques. 413 patients attending a contact dermatitis clinic in Singapore were simultaneously patch tested with panels 1 and 2 of the TRUE Test standard series and with corresponding allergens (Hermal, Hamburg) using Finn Chambers. The left/right application of the TRUE Test and Finn Chambers was randomized. The concordance of positive patch test reactions to the 2 test techniques was studied. The number of patient with positive reactions was 38% and 42% for TRUE Test and Finn Chamber techniques, respectively (n.s.). The overall concordance of positive patch test reactions was 64% (209/328). 13% (42/328) of positive reactions appeared on TRUE Test only and 24% (77/328) on Finn Chamber only. When only relevant positive reactions were considered, the concordance rate was 67%; 11.6% of positive reactions appeared on TRUE Test only and 21% on Finn Chamber only. Positive reactions to p-phenylenediamine (PPD) and neomycin were more frequent with the Finn Chamber technique than with TRUE Test, i.e., false negative reactions to PPD and neomycin were more likely to occur with TRUE Test. It appeared that the TRUE Test and Finn Chamber techniques were comparable when used for patch testing. However false negative and false positive patch test reactions can occur when using either technique.

Adolescent↗
PubMed1970

Further studies on metachromasia in cultured human fibroblasts. Staining of glycosaminoglycans (mucopolysaccharides) by Alcian blue in salt solutions.

Staining with Alcian blue in various concentrations of magnesium chloride (alcianophilia) has been found to be a useful supplement to metachromatic staining to detect increased cellular concentrations of glycosaminoglycans (mucopolysaccharides). In many instances alcianophilia at 0.3 M MgCl(2) is more specific than metachromasia and does not give "false positives" sometimes found in normal individuals and in those with cystic fibrosis, Gaucher's disease, familial amaurotic idiocy, and pseudoxanthoma elasticum. On the other hand, it gives a "false negative" reaction in the Sanfilippo syndrome (perhaps because the characteristically elevated glycosaminoglycan in this disease, heparan sulfate, is not synthesized by cultured skin fibroblasts), and in the Marfan syndrome. It detects the Maroteaux-Lamy syndrome, which metachromasia does not. The "false positives" given by metachromasia in all six families studied thus far are genuine, reproducible reactions that can be traced through at least three generations of normal individuals within a family. There is therefore, in these families, a genetic factor that causes such metachromasia, but it is not increased glycosaminoglycan concentration.

Adult↗
PubMed1997

Patch testing to detect corticosteroid allergy: is it adequate?

Whilst patch testing with corticosteroids in ethanol is more sensitive than either petrolatum or the cream formulation, the frequency of false-negative reactions is not known. We have compared patch testing with corticosteroid at 1% in ethanol with intradermal (i.d.) tests using 1 mg corticosteroid suspended in normal saline. Patch tests with tixocortol pivalate and budesonide detected all patients allergic to hydrocortisone and budesonide, respectively. For other corticosteroids, the use of ethanol as a vehicle resulted in both false-positive and false-negative reactions. In particular, patch tests with hydrocortisone-17-butyrate missed 30% of all positive reactions detected by i.d. testing. There may be a case for advising the avoidance of this steroid in all patients who are positive on patch testing to tixocortol pivalate and budesonide.

Anti-Inflammatory Agents↗
PubMed1980

A comparison of the IFA and the ELISA for the demonstration of antibodies against schistosome gut-associated polysaccharide antigens in schistosomiasis.

The applicability of two immunodiagnostic techniques was studied for the detection of antibodies against schistosome gut-associated polysaccharide antigens in human schistosomiasis mansoni: the immunofluorescent antibody reaction (IFA) using Rossman's fixed paraffin sections of adult worms and the enzyme-linked immunosorbent assay (ELISA) with a trichloroacetic acid soluble fraction of total adult worm antigens (AWA-TCA). With the IFA, gut-associated polysaccharide antigens could be demonstrated with an anti-IgM conjugate in a high percentage of the sera tested, although false-negative reactions were occasionally recorded. The use of an anti-IgG conjugate resulted in the demonstration of antibodies against additional antigens in the parenchyma of the worm and on the tegument. Specific IgM antibodies were present in higher concentrations in the sera from children than in those from adults. Using AWA-TCA as the antigen preparation in the ELISA, only antibodies against the circulating anodic antigen (CAA) could be demonstrated. Pretreatment of the ELISA-plates with poly-L-lysine to couple AWA-TCA was not necessary. The ELISA was successfully applied with anti-Ig, anti IgG, and anti-IgM conjugates. With anti-Ig conjugate the test was very sensitive and gave less false-negative reactions than the IFA. There was a significant difference between Ig, IgG, and IgM titres of children and adults. The use of an immunogalactosidase assay with a fluorogenic substrate in the ELISA, resulted in a test which was able to detect antibodies at ten times higher dilutions than with the immunoperoxidase assay.

Adolescent↗
PubMed1982

Delayed cutaneous hypersensitivity testing.

The topic of delayed cutaneous hypersensitivity testing is reviewed. When skin tests are used to determine whether an individual is anergic, T cell immunity is evaluated. Skin testing can be used to determine the causative organisms of infection or to discover an immunologic deficiency state. Characteristic skin lesions usually develop after intradermal injection of the antigen. Skin testing uses the most ubiquitous environmental antigens and those that are safe, cheap, and effective. Important issues dealing with skin tests include false-positive and false-negative reactions, which antigens to use in an antigen "battery," their lack of standardization, and the method of administration. Despite the problems, skin testing remains an easy, relatively safe method of assessing the immune system. Some investigators are developing more reliable testing methods and alternative antigens. Further research is needed to develop a reliable method for assessing delayed cutaneous hypersensitivity.

Antigens, Fungal↗
PubMed1988

Evaluation of excretory-secretory antigens for the serodiagnosis of swine trichinellosis.

Groups of hog sera from endemic and non-endemic areas for swine trichinellosis in Yugoslavia were tested by ELISA using excretory-secretory (ES) antigens collected from T. spiralis muscle larvae maintained in vitro for 24, 48 or 72 h. The 24-h ES had the highest level of specificity for T. spiralis infection. Antigen preparations recovered after 48 or 72 h yielded an increasing rate of false-positive reactions. Additional antigens occurred in the 48- and 72-h ES preparations as determined by gel electrophoresis and monoclonal antibody binding. The occurrence of false-negative reactions was directly correlated with T. spiralis worm burdens. Hogs with muscle larvae densities greater than 10 larvae per gram were all positive by ELISA. Among 17 hogs with less than 10 larvae per gram, only one hog was negative by ELISA with 24-h ES antigen; the false-negative rate was higher with 48- and 72-h ES. These results show that ES antigen produced during the first 24 h of in vitro cultivation is highly specific for the immunodiagnosis of swine trichinellosis.

Animals↗
PubMed1990

Rapid identification of Pasteurella multocida organisms responsible for haemorrhagic septicaemia using an enzyme-linked immunosorbent assay.

Haemorrhagic septicaemia (HS) is caused by specific serotypes of Pasteurella multocida and is one of the major economic diseases of cattle and buffalo in South East Asia. Definitive diagnosis of the disease-causing organism with the available methods is labour intensive and not totally reliable, consequently, an ELISA system to identify P multocida organisms which cause HS was developed. One hundred and twenty-four P multocida isolates were tested, 58 were type strains and 66 were field isolates. Analysis of these strains indicated the assay had a specificity of 99 per cent and sensitivity of at least 86 per cent. The sensitivity could be an underestimate, as five isolates assumed to be false negative reactions may not all be HS-causing strains. The HS ELISA provides a rapid, simple, accurate and inexpensive diagnostic assay for identification of HS causing organisms but does not represent a new typing system for P multocida. This assay will also enable countries to assess the impact of HS more accurately.

Animals↗
PubMed1986

Testing for antibodies to AIDS-associated retrovirus (HTLV-III/LAV) by indirect fixed cell immunofluorescence: specificity, sensitivity, and applications.

Seropositivity to the AIDS-associated retrovirus, HTLV-III/LAV, has profound implications. Simple and reliable tests are needed to detect such antibodies. A rapid, sensitive indirect immunofluorescence assay (IFA) on acetone-fixed virus-producing CEM/LAV-N1 cells was adapted for detection of human antibodies to HTLV-III/LAV. Specific and nonspecific patterns of of immunofluorescent reactivity were easily distinguished, and results paralleled those obtained by Western blotting and radioimmunoprecipitation (RIP), indicating that there is no need to confirm IFA positivity. In contrast, the commercial enzyme-linked immunosorbent assay (ELISA) was less reliable. False positives occurred with sera from seven hemophiliacs that were negative on Western blots, and false-negative reactions were observed on two occasions. These involved low-titer AIDS-patients' sera that were positive on Western blots, and from one of which virus was successfully isolated. Our results emphasize the requirement for confirmatory assays when the ELISA test is used for primary screening of sera for antibodies to HTLV-III/LAV. The IFA method is especially well-suited to quantitative analysis of serum antibody levels. Our data suggest that serum antibody titers rise as disease progression occurs, ultimately falling as severe complications ensue. It is suggested that in laboratories where the demand for HTLV-III/LAV antibody testing is not excessive (1,000-2,000 sera/month), IFA could serve as the only serological assay for both screening and epidemiological purposes.

Acquired Immunodeficiency Syndrome↗