• 제목/요약/키워드: False-negative results

검색결과 302건 처리시간 0.026초

An improvement of real-time polymerase chain reaction system based on probe modification is required for accurate detection of African swine fever virus in clinical samples in Vietnam

  • Tran, Ha Thi Thanh;Dang, Anh Kieu;Ly, Duc Viet;Vu, Hao Thi;Hoang, Tuan Van;Nguyen, Chinh Thi;Chu, Nhu Thi;Nguyen, Vinh The;Nguyen, Huyen Thi;Truong, Anh Duc;Pham, Ngoc Thi;Dang, Hoang Vu
    • Asian-Australasian Journal of Animal Sciences
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    • 제33권10호
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    • pp.1683-1690
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    • 2020
  • Objective: The rapid and reliable detection of the African swine fever virus (ASFV) plays an important role in emergency control and preventive measures of ASF. Some methods have been recommended by FAO/OIE to detect ASFV in clinical samples, including realtime polymerase chain reaction (PCR). However, mismatches in primer and probe binding regions may cause a false-negative result. Here, a slight modification in probe sequence has been conducted to improve the qualification of real-time PCR based on World Organization for Animal Health (OIE) protocol for accurate detection of ASFV in field samples in Vietnam. Methods: Seven positive confirmed samples (four samples have no mismatch, and three samples contained one mutation in probe binding sites) were used to establish novel real-time PCR with slightly modified probe (Y = C or T) in comparison with original probe recommended by OIE. Results: Both real-time PCRs using the OIE-recommended probe and novel modified probe can detect ASFV in clinical samples without mismatch in probe binding site. A high correlation of cycle quantification (Cq) values was observed in which Cq values obtained from both probes arranged from 22 to 25, suggesting that modified probe sequence does not impede the qualification of real-time PCR to detect ASFV in clinical samples. However, the samples with one mutation in probe binding sites were ASFV negative with OIE recommended probe but positive with our modified probe (Cq value ranked between 33.12-35.78). Conclusion: We demonstrated for the first time that a mismatch in probe binding regions caused a false negative result by OIE recommended real-time PCR, and a slightly modified probe is required to enhance the sensitivity and obtain an ASF accurate diagnosis in field samples in Vietnam.

모형 구성 과정에서 나타나는 초등학생의 인지, 감정적 반박 -인식적 감정을 중심으로- (Elementary Students' Cognitive-Emotional Rebuttals in Their Modeling Activity: Focusing on Epistemic Affect)

  • 한문현;김희백
    • 한국과학교육학회지
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    • 제37권1호
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    • pp.155-168
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    • 2017
  • 본 연구는 초등학생들이 모형 구성 과정에서 어떻게 인지, 감정적 반박을 사용했는지, 특히 그들의 감정과 인지적 과정이 어떻게 상호 작용하여 반박이 나타나게 되었는지 탐색한 것이다. 초등학교 5학년, 25명이 과학 수업의 일환으로 연구에 참여하였다. 6차시 동안 학생들은 지속적인 논의를 통해 인간 호흡 운동 시스템 모형을 구성하였다. 연구 결과에 따르면 초등학생들은 모형 구성 과정에서 정교화형 반박, 방어형 반박, 비난형 반박을 사용하였다. 인지적 비형형 상태와 연관된 부정적 인식적 감정과 인지적 과정의 상호작용을 통해 나타난 정교화형 반박은 소집단 모형을 정교화하는데 도움을 주었다. 반면 관계 악화와 관련된 부정적 인식적 감정과 인지적 과정의 상호작용을 통해 나타난 방어형 반박과 비난형 반박은 모형의 정교화를 이끌기보다는 다른 학생들의 제안, 설명을 배제하거나 공격하기 위해 사용되었고, 이 때의 부정적 인식적 감정은 다른 학생들의 바람직하지 않은 행동에 의해 생성되었다. 연구 결과는 학생들의 반박이 인식적 감정과 관련된 인식론적 역동에 의해 나타나게 됨을 보여준다. 본 연구는 학생들의 초보적, 수정될 필요가 있는 설명으로부터 부정적 인식적 감정이 생성되는 것은 모형 구성 과정에서 모형 발달을 돕는 정교화형 반박이 나타나게 되는 측면에서는 자연스러운 것이며, 정교화형 반박을 수용하도록 돕는 학생들의 감정 조절은 모형을 발달시키는데 도움이 될 수 있음을 논의한다. 또한 관계의 악화로 인해 나타날 수 있는 부정적 인식적 감정은 초등학생이 조절하기 어려우며, 이것이 협력적 모형 구성을 어렵게 할 수 있음을 제언한다.

Robust Reference Intervals for Serum Kappa and Lambda Free Light Chains from a Multi Centre Study Population from Hyderabad, India: Myeloma Diagnostic Implications

  • Mohammed, Noorjahan;Chandran, Priscilla Abraham;Kandregula, Madhavi;Mattaparthi, Ratna Deepika;Gundeti, Sadasivudu;Volturi, Jyotsna;Darapuneni, Radhika;Raju, Sree Bhushan;Dattatreya, Palanki Satya
    • Asian Pacific Journal of Cancer Prevention
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    • 제17권5호
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    • pp.2605-2610
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    • 2016
  • The International Myeloma Working Group considers the serum free light chain (SFLC) assay to be an adjunct to traditional tests. Apart from the FLC ratio, the absolute values of individual free light chains also are gaining importance as they appear to be more relevant in certain clinical settings. Automated assays are available for their determination. As laboratories put new test systems into use catering to different disease populations, they are required by accreditation and certification bodies to verify or establish performance specifications, including reference intervals (RIs) representative of their population. Our aim was to establish local RIs for SFLC in a multicentre representative healthy population using a robust method. There was no significant relationship between SFLC levels and age, gender and creatinine levels. The 95% RI for ${\kappa}SFLC$ was 4.81 to 33.86mg/L, for ${\lambda}$ SFLC was 5.19 to 23.67mg/L and for ${\kappa}/{\lambda}SFLC$ was 0.36 to 2.33, significantly higher than the values given by the manufacturer. The ${\kappa}/{\lambda}$ SFLC ratio at 2.23, covering 100% of the data, showed 72% sensitivity (95% CI=39.0 - 94.0), 100% specificity (95% CI=71.5 - 100.0), 100% PPV (95% CI=21.5 - 100.0), 95% NPV (95% CI=75.4 - 99.9), and 79% accuracy (95% CI=56.0 - 93.0). In the patient group, kit RI for ${\kappa}/{\lambda}$ SFLC ratio classified 45.5% (n=5) as positive vs 9.1% (n=1) positive by the study RI, while the kit RI for kappa FLC classified 90.9% (n=10) as positive vs 54.5% (n=6), indicating increased probability of false positive test results with the kit RI when applied to our patient population. Appropriate and specific reference intervals and criteria values result in fewer false-positive and false-negative results which means fewer wrong or missed diagnoses.

Ultrasonographic Features of Triple-Negative Breast Cancer: a Comparison with Other Breast Cancer Subtypes

  • Yang, Qi;Liu, Hong-Yan;Liu, Dan;Song, Yan-Qiu
    • Asian Pacific Journal of Cancer Prevention
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    • 제16권8호
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    • pp.3229-3232
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    • 2015
  • Background: Triple-negative breast cancer (TNBC) is known to be associated with aggressive biologic features and a poor clinical outcome. Therefore, early detection of TNBC without missed diagnosis is a requirement to improve prognosis. Preoperative ultrasound features of TNBC may potentially assist in early diagnosis as characteristics of disease. Purpose: To retrospectively evaluate the sonographic features of TNBC compared to ER (+) cancers which include HER(-) and HER2 (+), and HER2 (+) cancers which are ER (-). Materials and Methods: From June 2012 through June 2014, sonographic features of 321 surgically confirmed ER (+) cancers (n=214), HER2 (+) cancers (n=66), and TNBC (n=41) were retrospectively reviewed by two ultrasound specialists in consensus. The preoperative ultrasound and clinicopathological features were compared between the three subtypes. In addition, all cases were analyzed using morphologic criteria of the ACR BI-RADS lexicon. Results: Ultrasonographically, TNBC presented as microlobulated nodules without microcalcification (p=0.034). A lower incidence of ductal carcinoma in situ (p<0.001), invasive tumor size that is>2 cm (p=0.011) and BI-RADS category 4 (p<0.001) were significantly associated with TNBC. With regard to morphologic features of 41 TNBC cases, ultrasonographically were most likely to be masses with irregular (70.7%) microlobulated shape (48.8%), be circumscribed (17.1%) or have indistinct margins (17.1%) and parallel orientation (68.9%). Especially TNBC microlobulated mass margins were more more frequent than with ER (+) (2.0%) and HER2 (+) (4.8%) cancers. Conclusions: TNBC have specific characteristic in sonograms. Ultrasonography may be useful to avoid missed diagnosis and false-negative cases of TNBC.

Comparison of Culture, Conventional and Real-time PCR Methods for Listeria monocytogenes in Foods

  • Kim, Dong-Hyeon;Chon, Jung-Whan;Kim, Hyunsook;Kim, Hong-Seok;Choi, Dasom;Kim, Young-Ji;Yim, Jin-Hyeok;Moon, Jin-San;Seo, Kun-Ho
    • 한국축산식품학회지
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    • 제34권5호
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    • pp.665-673
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    • 2014
  • We compared standard culture methods as well as conventional PCR and real-time PCR for the detection of Listeria monocytogenes (L. monocytogenes) in milk, cheese, fresh-cut vegetables, and raw beef that have different levels of background microflora. No statistical differences were observed in sensitivity between the two selective media in all foods. In total, real-time PCR assay exhibited statistically excellent detection sensitivity (p<0.05) and was less time consuming and laborious as compared with standard culture methods. Conventional culture methods showed poor performance in detecting L. monocytogenes in food with high levels of background microflora, generating numerous false negative results. While the detection of L. monocytogenes in fresh cut vegetable by culture methods was hindered only by L. innocua, various background microflora, such as L. innocua, L. welshimeri, L. grayi, and Enterococcus faecalis appeared on the two selective media as presumptive positive colonies in raw beef indicating the necessity of improvement of current selective media. It appears that real-time PCR is an effective and sensitive presumptive screening tool for L. monocytogenes in various types of foods, especially foods samples with high levels of background microflora, thus complementing standard culture methodologies.

Development of a Novel Immunochromatographic Assay for Rapid Detection of OXA-23 β-lactamase-producing Acinetobacter baumannii

  • Ji, Gil Young;Song, Hyung Geun;Jo, Mi Young;Hong, Seung Bok;Shin, Kyeong Seob
    • 대한의생명과학회지
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    • 제22권2호
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    • pp.29-36
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    • 2016
  • Among the several agents causing carbapenem resistance of Acinetobacter baumannii, the most common cause is OXA-23 ${\beta}$-lactamase, which is known to hydrolyze carbapenem. To effectively control dissemination of carbapenem-resistant Acinetobacter baumannii (CRAB), development of both rapid and easy-to-use detection methods are required. The aim of this study is to develop a novel immunochromatographic assay (ICA) for rapid detection of OXA-23 ${\beta}$-lactamase. Of the seven monoclonal antibodies (mAbs) screened by ELISA, four mAbs (4G6, 4H6, 6G4, 9A4) exhibited high reactivity. Of these four specific antibodies, the combination of 6G4/4G6 showed the greatest reactivity and this combination of mAbs (6G4/4G6 mAbs) was used to develop the OXA-23 ${\beta}$-lactamase ICA. Of 102 A. baumannii isolates tested, the OXA-23 ${\beta}$-lactamase ICA results were consistent with PCR analysis except one false positive and one false negative isolate. The overall sensitivity and specificity were 98.36% and 97.56%, respectively. In conclusion, to the best of our knowledge, we have developed the first specific antibody set to detect OXA-23 ${\beta}$-lactamase using an ICA kit. This novel ICA can be used as a reliable and easy-to-use immunological assay for detection of OXA-23 ${\beta}$-lactamase producing CRAB in clinical laboratories.

Comparative Evaluation of Intron Prediction Methods and Detection of Plant Genome Annotation Using Intron Length Distributions

  • Yang, Long;Cho, Hwan-Gue
    • Genomics & Informatics
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    • 제10권1호
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    • pp.58-64
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    • 2012
  • Intron prediction is an important problem of the constantly updated genome annotation. Using two model plant (rice and $Arabidopsis$) genomes, we compared two well-known intron prediction tools: the Blast-Like Alignment Tool (BLAT) and Sim4cc. The results showed that each of the tools had its own advantages and disadvantages. BLAT predicted more than 99% introns of whole genomic introns with a small number of false-positive introns. Sim4cc was successful at finding the correct introns with a false-negative rate of 1.02% to 4.85%, and it needed a longer run time than BLAT. Further, we evaluated the intron information of 10 complete plant genomes. As non-coding sequences, intron lengths are not limited by a triplet codon frame; so, intron lengths have three phases: a multiple of three bases (3n), a multiple of three bases plus one (3n + 1), and a multiple of three bases plus two (3n + 2). It was widely accepted that the percentages of the 3n, 3n + 1, and 3n + 2 introns were quite similar in genomes. Our studies showed that 80% (8/10) of species were similar in terms of the number of three phases. The percentages of 3n introns in $Ostreococcus$ $lucimarinus$ was excessive (47.7%), while in $Ostreococcus$ $tauri$, it was deficient (29.1%). This discrepancy could have been the result of errors in intron prediction. It is suggested that a three-phase evaluation is a fast and effective method of detecting intron annotation problems.

구강내 병변의 세침흡인 세포학적 소견 (Fine Needle Aspiration Cytology of Intraoral Lesions)

  • 이호정;공경엽;정동해;허주령;김온자
    • 대한세포병리학회지
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    • 제9권2호
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    • pp.155-159
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    • 1998
  • Fine needle aspiration cytology(FNAC) has become a popular method for the diagnosis of a wide variety of both superficial and deep-seated lesions. However, there are few reports about the potential of FNAC for the diagnosis of intraoral lesions. We experienced 44 FNACS from intraoral lesions at Asan Medical Center: 22 from the palate, 6 from the tongue, 5 from the parapharyngeal space, 5 from the lip, 2 from the floor of mouth, 1 from the buccal mucosa, and 3 from other intraoral sites. Histological confirmation was obtained in 32 cases and we analyzed 27 cases excluding 5 cases of inadequate aspirates. Diagnosis was specifically made in 19 of 27 cases(70%) including 1 mucoepidermoid carcinoma, 1 undifferentiated carcinoma, 1 chordoma, 9 pleomorphic adenomas, 1 neurofibroma, and 6 benign lesions. There were three false negative cases(sensitivity, 62.5%) and no false positive cases(specificity, 100%): Two cases diagnosed as "cystic lesion" were confirmed to be mucoepidermoid carcinomas and a case diagnosed as pleomorphic adenoma was proved to be adenoid cystic carcinoma. The results of our study suggest that FNAC is a useful technique in the diagnosis of intraoral lesion.

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망혼용단말 탐지방법에 대한 연구 및 자동탐지시스템 구현 (A Study on Detection Method of Multi-Homed Host and Implementation of Automatic Detection System for Multi-Homed Host)

  • 이미화;윤지원
    • 정보보호학회논문지
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    • 제28권2호
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    • pp.457-469
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    • 2018
  • 본 연구에서는 망혼용단말(Multi-homed host)이 사라지지 않는 근본원인과 위험성을 알아보았다. 또한, 지금까지 연구 개발된 망혼용단말 탐지방법에 대해 비교 분석하여 개선사항을 도출하였다. 도출한 개선사항을 반영하여 망혼용단말을 효과적으로 탐지할 수 있는 자동 탐지시스템 모델을 제안하고 구현하였다. 아울러, 개발한 탐지시스템을 실제 망분리 기관과 유사한 가상실험환경에 설치한 후, 망혼용단말을 유형별로 발생시켜가며 탐지시스템의 기능과 성능을 측정하였다. 본 연구 범위에서는 오탐과 미탐 없이 정상 작동됨을 확인하였다. 제안한 탐지시스템은 에이전트(Agent) 기반 방식 중, 망혼용단말 탐지를 목표로한 최초의 학술 연구이다.

전기전도도(電氣傳導度) 측정(測定)에 의한 유우(乳牛) 준임상형(準臨床型) 유방염(乳房炎)의 진단(診斷)에 관한 연구(硏究) 1. 전기전도도법(電氣傳導度法)과 간접검진법(間接檢診法)(CMT 및 총체세포수(總體細胞數))과의 비교(比較) (Studies on the Diagnosis of Subclinical Mastitis in Cows by the Measurement of the Electrical Conductivity: 1. Comparison of Various Methods of Handling Conductivity Data with the Use of California Mastitis Test and Direct Somatic Cell Count)

  • 강병규
    • 대한수의학회지
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    • 제24권1호
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    • pp.91-98
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    • 1984
  • A total of 466 foremilk from dairy farms in Chonnam district was examined for the subclinical mastitis over a period of one year, using a method of the electrical conductivities(EC); absolute conductivity(AC) and differential conductivity(DC) and quarter difference value(QD), in relation to the California mastitis test(CMT) and the direct somatic cell count(DSCC). The compatibility and efficiency rating between the EC values and the other screening tests was conducted. Obtained results are summarized as follows. 1. A linear relationship was found between the EC values and the CMT scores and direct somatic cell counts and it was found that electrical conductivity measurements were comparable with other screening tests for diagnosing animals with mastitis. 2. Compatibilities between the EC and CMT were 70.4% in AC, 74.6% in DC and 70.7% in QD, and that of the EC and DSCC were 53.0% in AC, 63.1% in DC and 53.2% in QD. On the other hand, relative efficiency ratings of Postle's equation between EC and CMT were 37.3% in AC, 26.5% in DC and 13.6% in QD, and that of the EC and DSCC were 33.1% in AC, 20.2% in DC and 11.9% in QD. 3. In the foremilk samples collected from damaged quarters determined by EC, the false positive rate wart higher than the false negative rate, and consequently tests of EC produced lower compatibility or efficiency rating scores. These tendencies suggested that any factors other than the mastitic condition influencing the EC values might be existed.

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