Displaying publications 1 - 20 of 32 in total

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  1. A false-positive result with the American Society for Testing and Materials D5712-95 test method for protein given by a common vulcanization accelerator
    Chen SF, Teoh SC, Porter M
    J Allergy Clin Immunol, 1997 Nov;100(5):713-4.
    PMID: 9389305
    Matched MeSH terms: False Positive Reactions
  2. Letter: Disappointing results in Malaysia with the "Dill Glazko" eosin colour tests for chloroquine in urine
    Dondero TJ, Mariappan M
    Trans R Soc Trop Med Hyg, 1974;68(4):338-9.
    PMID: 4419901
    Matched MeSH terms: False Positive Reactions
  3. Evaluation of an Immunoglobulin E Capture Enzyme-Linked Immunosorbent Assay for the Early Diagnosis of Dengue
    Machain-Williams C, Reyes-Solis GC, Blitvich BJ, Laredo-Tiscareño V, Dzul-Rosado AR, Kim S, et al.
    Viral Immunol, 2023 Mar;36(2):101-109.
    PMID: 36862827 DOI: 10.1089/vim.2022.0110
    Dengue virus (DENV) is the etiological agent of dengue, the most important mosquito-transmitted viral disease of humans worldwide. Enzyme-linked immunosorbent assays (ELISAs) designed to detect DENV IgM are commonly used for dengue diagnosis. However, DENV IgM is not reliably detected until ≥4 days after illness onset. Reverse transcription-polymerase chain reaction (RT-PCR) can diagnose early dengue but requires specialized equipment, reagents, and trained personnel. Additional diagnostic tools are needed. Limited work has been performed to determine whether IgE-based assays can be used for the early detection of vector-borne viral diseases, including dengue. In this study, we determined the efficacy of a DENV IgE capture ELISA for the detection of early dengue. Sera were collected within the first 4 days of illness onset from 117 patients with laboratory-confirmed dengue, as determined by DENV-specific RT-PCR. The serotypes responsible for the infections were DENV-1 and DENV-2 (57 and 60 patients, respectively). Sera were also collected from 113 dengue-negative individuals with febrile illness of undetermined etiology and 30 healthy controls. The capture ELISA detected DENV IgE in 97 (82.9%) confirmed dengue patients and none of the healthy controls. There was a high false positivity rate (22.1%) among the febrile non-dengue patients. In conclusion, we provide evidence that IgE capture assays have the potential to be explored for early diagnosis of dengue, but further research is necessary to address the possible false positivity rate among patients with other febrile illnesses.
    Matched MeSH terms: False Positive Reactions
  4. Prevalence of latex allergy may be vastly overestimated when determined by in vitro assays
    Yeang HY
    Ann. Allergy Asthma Immunol., 2000 Jun;84(6):628-32.
    PMID: 10875493 DOI: 10.1016/S1081-1206(10)62415-5
    BACKGROUND:
    The prevalence of latex-specific IgE computed from the results of serologic assays is commonly thought to reflect, to a greater or lesser extent, the prevalence of latex allergy and its implied risk.

    OBJECTIVE:
    The study examines how imperfect test specificity of in vitro assays influences the precision of latex allergy prevalence that it estimates.

    METHODS:
    Various models encompassing a range of hypothetical test sensitivity and specificity values are investigated to gauge their influence on the estimate of latex allergy prevalence. The models examine these interactions in situations of high or low allergy prevalence.

    RESULTS:
    Serologic latex diagnostic assays with test specificity within the range of those of commercially available assays can greatly overestimate prevalence where the true prevalence is low (eg, of the order of one in 100 or one in 1,000). A formula to correct for errors in prevalence estimates arising from imperfect test sensitivity and specificity of an in vitro assay is presented.

    CONCLUSION:
    While serologic assays for latex IgE pose few hazards to the patient and are useful for confirming the diagnosis of latex allergy, the test results may vastly overestimate the true prevalence of latex allergy and its associated risks in situations where latex allergy is actually rare.
    Matched MeSH terms: False Positive Reactions
  5. Fulltext Clinical significance of Mantoux test in Malaysian patients
    Yaacob I, Ahmad Z
    Med J Malaysia, 1990 Sep;45(3):231-4.
    PMID: 2152084
    The value of tuberculin skin testing in the diagnosis of active tuberculosis remains uncertain. Interpretation of tuberculin tests would be easier if the tuberculin test profiles in different communities were accurately known. We reviewed 468 Mantoux test reactions in patients coming to Hospital Universiti Sains Malaysia with suspected tuberculosis. Eighty six percent of patients with active tuberculosis had a positive Mantoux test. Forty two percent of the cases of positive Mantoux test did not have evidence of active tuberculosis. Most of these cases had evidence of past infection with tuberculosis. We conclude that Mantoux test is a sensitive but a non-specific test in the diagnosis of active tuberculosis.
    Study site: outpatients, inpatients; Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
    Matched MeSH terms: False Positive Reactions
  6. False-positive widal test in nontyphoid Salmonella infections
    Pang T, Pothocheary SD
    Southeast Asian J. Trop. Med. Public Health, 1989 Mar;20(1):163-4.
    PMID: 2672364
    Matched MeSH terms: False Positive Reactions
  7. Seroreactivity to syphilis in Malaysian blood donors and expectant mothers
    Jegathesan M, Fan YH, Ong KJ
    Southeast Asian J. Trop. Med. Public Health, 1975 Sep;6(3):413-8.
    PMID: 1241163
    Seroreactivity to syphilis is high among Malaysian blood donors and expectant mothers indicating a high degree of treponemal infection. Further epidemiological studies are required to ascertain what proportion of these could be syphilis and what porportion yaws. Blood donors hava a higher reactivity rate than expectant mothers, the reasons probably being soical. The titres obtained in the VDRL test appear to have a relation to FTA-ABS reactivity although this is not to say treponematosis can be excluded on the basis of low titre VDRL results.
    Matched MeSH terms: False Positive Reactions
  8. Seroprevalence of hepatitis C virus infection among blood donors in a teaching hospital in northeastern Malaysia
    Haslina MN, Khairiah Y, Zainy DZ, Shafini MY, Rosnah B, Marini R
    Southeast Asian J. Trop. Med. Public Health, 2012 May;43(3):668-73.
    PMID: 23077846
    The aim of this study was to determine the prevalence of HCV infection and the signal/cutoff (S/CO) value for false reactive, false positive, indeterminate and true positive HCV infection among apparently healthy blood donors in our area. This retrospective study was conducted at the Transfusion Medicine Unit, Hospital Universiti Sains Malaysia from June 2008 to June 2009. Blood samples were screened for anti-HCV using enzyme immunoassay (EIA). Reactive cases were confirmed by recombinant immunoblot assay (RIBA). Sixty-one blood donors were found to be reactive after the first screening test. Twenty-nine blood donors had reactive repeat screening, with only 9 samples being true positives. The S/ CO for false reactive, false positive, indeterminate and true positive anti-HCV samples were 1.02 to 1.45, 1.01 to 2.09, 1.07 to 2.43 and 35.95 to 119.89, respectively. The analysis showed the low incidence of HCV infections among blood donors in our area, however, thorough donor screening and stringent selection criteria are still recommended to eliminate high risk donors to improve our blood transfusion service.
    Matched MeSH terms: False Positive Reactions
  9. Fulltext An audit of intraoperative frozen section in Johor
    Khoo JJ
    Med J Malaysia, 2004 Mar;59(1):50-5.
    PMID: 15535336 MyJurnal
    A 4-year-review was carried out on intraoperative frozen section consultations in Sultanah Aminah Hospital, Johor Bahru. Two hundred and fifteen specimens were received from 79 patients in the period between January 1999 and December 2002. An average of 2.72 specimens per patient was received. The overall diagnostic accuracy was high, 97.56%. The diagnoses were deferred in 4.65% of the specimens. False positive diagnoses were made in 3 specimens (1.46%) and false negative diagnoses in 2 specimens (0.98%). This gave an error rate of 2.44%. The main cause of error was incorrect interpretation of the pathologic findings. In the present study, frozen sections showed good sensitivity (97.98%) and specificity (97.16%). Despite its limitations, frozen section is still generally considered to be an accurate mode of intraoperative consultation to assist the surgeon in deciding the best therapeutic approach for his patient at the operating table. The use of frozen section with proper indications was cost-effective as it helped lower the number of reoperations. An audit of intraoperative frozen section from time to time serves as part of an ongoing quality assurance program and should be recommended where the service is available.
    Matched MeSH terms: False Positive Reactions
  10. Use of capnography delaying the diagnosis of tracheal intubation
    Chan YK, Zuraidah S, Tan PS
    Anaesthesia, 1998 Dec;53(12):1207-8.
    PMID: 10193227
    There was a delay in making the correct diagnosis of tracheal intubation in a parturient who developed severe bronchospasm after intubation because we relied on the capnogram.
    Matched MeSH terms: False Positive Reactions
  11. A pseudo-cryptococcal artefact derived from leucocytes in wet India ink mounts of centrifuged cerebrospinal fluid
    Thiruchelvan N, Wuu KY, Arseculeratne SN, Ashraful-Haq J
    J Clin Pathol, 1998 Mar;51(3):246-8.
    PMID: 9659271
    Wet India ink mounts of cerebrospinal fluid (CSF) are useful in the laboratory diagnosis of cryptococcal meningitis. Pseudo-cryptococcal artefacts in such mounts have been attributed to leucocytes in CSF but their mode of formation has not been explained. This report describes the reproduction of such an artefact in cryptococcus free CSF-leucocyte mixtures that had been subjected to high speed centrifugation. The viscosity of DNA that could provide a morphological pseudo-capsule, and the yellow-green fluorescence of the pseudo-capsular material on staining with acridine-orange, suggest that lymphocytic nuclear DNA, which possibly leaked out after damage to the lymphocyte membrane by centrifugation, was responsible for this artefact.
    Matched MeSH terms: False Positive Reactions
  12. Fulltext The Kveim test in leprosy
    Krishnamurthy S, Verghese R, Job CK
    Int. J. Lepr. Other Mycobact. Dis., 1975;43(4):333-8.
    PMID: 1241690
    The response to lepromin and Kveim antigens was compared and studied in 15 leprosy patients who were tuberculin negative. Of the 11 lepromin positive tuberculoid patients, 4 were Kveim positive, 1 was equivocal, and the rest were negative. Of the four lepromin negative lepromatous patients, one gave a positive Kveim test while the other three were negative. It has been shown that false-positive Kveim reactions are found in a higher percentage of South Indian leprosy patients than in those of other backgrounds, such as Japanese and Malaysian Chinese patients. It is also suggested that no definite relationship exists between the reaction of leprosy patients to lepromin and Kveim antigens. We further suggest that the anergy exhibited by lepromatous patients to the antigen of M. leprae is specific, as evidenced by the positive Kveim response in one lepromatous patient.
    Matched MeSH terms: False Positive Reactions
  13. Clinical judgement perplexed by initially undisclosed use of herbal medicine and unexpected cross-reactivity of immunoassay
    Liu KT, Lee CW
    Malays J Pathol, 2017 Aug;39(2):189-192.
    PMID: 28866703
    We report a case of symptomatic bradycardia caused by consumption of a Chinese herbal medicine which was initially undisclosed to the attending emergency physician. The scientific name of the herb is Panax japonicus. Electrocardiogram revealed sinus bradycardia. Laboratory tests were normal except for the detection of a high serum digoxin level. Further interrogation of the patient eventually disclosed ingestion of the herb which, however, did not contain any digoxin. Other active ingredients in the herb include various types of ginsenoside. These are digoxin-like substances that had caused the observed false-positive detection of digoxin by fluorescence polarization immunoassay due to cross-reactivity. Our case-report provides an important insight about a blind-spot in the field of laboratory medicine (clinical pathology), namely, the false positive detection of digoxin due to crossreactivity in the immunoassay when we come across digoxin-like substances in clinical scenarios, which has barely received attention in the medical literature. It also conveys a clear educational message that with full understanding of the laboratory methodology and its mechanistic rationale there are actually some tricks-of-the-trade that allow us to optimize the specificity of the biochemical tests and the treatment of digoxin-like substances overdose.
    Matched MeSH terms: False Positive Reactions
  14. A new deformable model based on fractional Wright energy function for tumor segmentation of volumetric brain MRI scans
    Ibrahim RW, Hasan AM, Jalab HA
    Comput Methods Programs Biomed, 2018 Sep;163:21-28.
    PMID: 30119853 DOI: 10.1016/j.cmpb.2018.05.031
    BACKGROUND AND OBJECTIVES: The MRI brain tumors segmentation is challenging due to variations in terms of size, shape, location and features' intensity of the tumor. Active contour has been applied in MRI scan image segmentation due to its ability to produce regions with boundaries. The main difficulty that encounters the active contour segmentation is the boundary tracking which is controlled by minimization of energy function for segmentation. Hence, this study proposes a novel fractional Wright function (FWF) as a minimization of energy technique to improve the performance of active contour without edge method.

    METHOD: In this study, we implement FWF as an energy minimization function to replace the standard gradient-descent method as minimization function in Chan-Vese segmentation technique. The proposed FWF is used to find the boundaries of an object by controlling the inside and outside values of the contour. In this study, the objective evaluation is used to distinguish the differences between the processed segmented images and ground truth using a set of statistical parameters; true positive, true negative, false positive, and false negative.

    RESULTS: The FWF as a minimization of energy was successfully implemented on BRATS 2013 image dataset. The achieved overall average sensitivity score of the brain tumors segmentation was 94.8 ± 4.7%.

    CONCLUSIONS: The results demonstrate that the proposed FWF method minimized the energy function more than the gradient-decent method that was used in the original three-dimensional active contour without edge (3DACWE) method.

    Matched MeSH terms: False Positive Reactions
  15. Detection of Epstein-Barr virus DNA in nasopharyngeal carcinoma using a non-radioactive digoxigenin-labelled probe
    Permeen AM, Sam CK, Pathmanathan R, Prasad U, Wolf H
    J Virol Methods, 1990 Mar;27(3):261-7.
    PMID: 2157729
    The presence of Epstein Barr virus (EBV) DNA in biopsies from the post-nasal space (PNS) of patients suspected of nasopharyngeal carcinoma (NPC) was detected by in situ cytohybridization with an EBV DNA probe labelled with the novel labelling compound digoxigenin. The digoxigenin probe was hybridised to cryostat sections of NPC biopsies and subsequently detected by an enzyme immunoassay procedure. It was found that in situ cytohybridization using the digoxigenin probe was much more rapid and sensitive (96 h compared to five weeks) than the current method of using 3H-labelled probe. Using the digoxigenin EBV probe, it was found that in all the eighteen NPC biopsies tested, EBV DNA was detected in malignant epithelial cells and infiltrating lymphocytes. EBV DNA was also detected in some normal epithelial cells in these NPC biopsies. EBV DNA was not detected in epithelial cells of non-malignant biopsies.
    Matched MeSH terms: False Positive Reactions
  16. Fulltext Phenotypic detection of metallo-β-lactamase in imipenem-resistant Pseudomonas aeruginosa
    Khosravi Y, Loke MF, Chua EG, Tay ST, Vadivelu J
    ScientificWorldJournal, 2012;2012:654939.
    PMID: 22792048 DOI: 10.1100/2012/654939
    Carbapenems are the primary choice of treatment for severe Pseudomonas aeruginosa infection. However, the emergence of carbapenem resistance due to the production of metallo-β-lactamases (MBLs) is of global concern. In this study, 90 imipenem- (IPM- or IP-) resistant P. aeruginosa (IRPA) isolates, including 32 previously tested positive and genotyped for MBL genes by PCR, were subjected to double-disk synergy test (DDST), combined disk test (CDT), and imipenem/imipenem-inhibitor (IP/IPI) E-test to evaluate their MBLs detection capability. All three methods were shown to have a sensitivity of 100%. However, DDST was the most specific of the three (96.6%), followed by IP/IPI E-test interpreted based on the single criteria of IP/IPI ≥8 as positive (62.1%), and CDT was the least specific (43.1%). Based on the data from this evaluation, we propose that only IRPA with IP MIC >16 μg/mL and IP/IPI ≥8 by IP/IPI E-test should be taken as positive for MBL activity. With the new dual interpretation criteria, the MBL IP/IPI E-test was shown to achieve 100% sensitivity as well as specificity for the IRPA in this study. Therefore, the IP/IPI E-test is a viable alternative phenotypic assay to detect MBL production in IRPA in our population in circumstances where PCR detection is not a feasible option.
    Matched MeSH terms: False Positive Reactions
  17. Fulltext Does performance of breast self-exams increase the probability of using mammography: evidence from Malaysia
    Dunn RA, Tan A, Samad I
    Asian Pac J Cancer Prev, 2010;11(2):417-21.
    PMID: 20843127
    OBJECTIVES: Breast self-examination (BSE) was evaluated to see if it is a significant predictor of mammography.

    METHODS: The decisions of females above age 40 in Malaysia to test for breast cancer using BSE and mammography are jointly modeled using a bivariate probit so that unobserved attributes affecting mammography usage are also allowed to affect BSE. Data come from the Malaysia Non-Communicable Disease Surveillance-1, which was collected between September 2005 and February 2006.

    RESULTS: Having ever performed BSE is positively associated with having ever undergone mammography among Malay (adjusted OR=7.343, CI=2.686, 20.079) and Chinese (adjusted OR=3.466, CI=1.330, 9.031) females after adjusting for household income, education, marital status and residential location. Neither relationship is affected by jointly modelling the decision problem. Although the association is also positive for Indian females when mammography is modelled separately (adjusted OR=5.959, CI=1.546 - 22.970), the relationship is reversed when both decisions are modelled separately.

    CONCLUSIONS: De-emphasizing BSE in Malaysia may reduce mammography screening among a large proportion of the population. Previous work on the issue in developed countries may not apply to nations with limited resources.
    Matched MeSH terms: False Positive Reactions
  18. Fulltext Diagnostic accuracy of reused Pronto Drytest and CLOtest in the detection of Helicobacter pylori infection
    Jamaludin S, Mustaffa N, Che Hamzah NA, Syed Abdul Aziz SH, Lee YY
    BMC Gastroenterol, 2015;15:101.
    PMID: 26264957 DOI: 10.1186/s12876-015-0332-0
    Unchanged substrate in a negative rapid urease test may be reused to detect Helicobacter pylori (H. pylori). This could potentially reduce costs and wastage in low prevalence and resource-poor settings. We thus aimed to investigate the diagnostic accuracy of reused Pronto Dry and CLOtest kits, comparing this to the use of new Pronto Dry test kits and histopathological evaluation of gastric mucosal biopsies.
    Matched MeSH terms: False Positive Reactions
  19. Specificity and sensitivity of a rapid dipstick test (Brugia Rapid) in the detection of Brugia malayi infection
    Rahmah N, Taniawati S, Shenoy RK, Lim BH, Kumaraswami V, Anuar AK, et al.
    Trans R Soc Trop Med Hyg, 2002 1 31;95(6):601-4.
    PMID: 11816429
    A total of 753 serum samples from 6 institutions in 3 countries (Malaysia, Indonesia and India) were used to evaluate an immunochromatographic rapid dipstick test, Brugia Rapid, for diagnosis of Brugia malayi infection. The samples comprised sera from 207 microfilaria-positive individuals and 546 individuals from filaria non-endemic areas. The latter consisted of 70 individuals with soil-transmitted helminth infections, 68 with other helminth infections, 238 with protozoan infections, 12 with bacterial and viral infections and 158 healthy individuals. The dipstick is prepared with a goat anti-mouse antibody control line and a B. malayi recombinant-antigen test line. First, the dipstick is dipped into a well containing diluted patient serum, thus allowing specific anti-filarial antibody in the serum to react with the recombinant antigen. Then the dipstick is placed into an adjacent well containing reconstituted anti-human IgG4-gold. After 10 min, development of 2 red-purplish lines denotes a positive result and one line indicates a negative reaction. The overall results of the evaluation showed 97% sensitivity, 99% specificity, 97% positive predictive value and 99% negative predictive value. Brugia Rapid is thus a promising diagnostic tool for detection of B. malayi infection, and would be especially useful for the brugian filariasis elimination programme.
    Matched MeSH terms: False Positive Reactions
  20. Effectiveness of a dot-blot immunoassay of anti-Rickettsia tsutsugamushi antibodies for serologic analysis of scrub typhus
    Weddle JR, Chan TC, Thompson K, Paxton H, Kelly DJ, Dasch G, et al.
    Am J Trop Med Hyg, 1995 Jul;53(1):43-6.
    PMID: 7625532
    We compared a commercially available dot-blot immunoassay system with the indirect immunofluorescence assay (IFA) in tests of known negative and known positive sera from scrub typhus cases. Using a panel of 100 sera from patients with various rickettsial and nonrickettsial infections, we observed that the IFA was 99% specific and the dipstick assay was 98% specific. In tests of 91 sera (30 negative and 61 positive for scrub typhus antibodies) from a study of febrile patients in Malaysia, using the standard of an IFA titer < 1:64 as negative, an IFA titer > 1:128 as positive, and an IFA titer = 1:64 as either positive or negative (supported by clinical records), dipsticks were 83% specific and 90% sensitive. The quantitative correlation of the dipsticks to IFA titers was confirmed by significant differences in geometric means of inverse IFA titers corresponding to the number of positive dipstick spots (no dots = 8.5, one dot = 43.3, two dots = 206.7, and three dots = 676.9). The assay would enable physicians and public health workers who deal with patients to quickly diagnose and appropriately treat most cases of the disease, especially in areas of high prevalence where the proportion of false-positive results to true-positive results would be low.
    Matched MeSH terms: False Positive Reactions
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