Immunofluorometric activity-based probe analysis of active KLK6 in biological fluids

2008 ◽  
Vol 389 (6) ◽  
Author(s):  
Katerina Oikonomopoulou ◽  
Kristina K. Hansen ◽  
Amos Baruch ◽  
Morley D. Hollenberg ◽  
Eleftherios P. Diamandis
Keyword(s):  
Biological Fluids ◽  
Specific Antigen ◽  
Serine Proteinase ◽  
Cancer Biomarkers ◽  
Active Enzyme ◽  
Clinical Samples ◽  
Diagnostic Indices ◽  
Antibody Capture ◽  
Probe Assay ◽  
Enzyme Species

Abstract Immunoassay measurements of human kallikrein-related peptidases (KLKs) such as prostate-specific antigen (KLK3) are of great value as diagnostic indices of cancer. Despite extensive knowledge of the abundance of immunoreactive KLKs in normal and cancer-related settings, there is little information available about the proportion of immunoreactive KLK that represents active enzyme in such samples. Using KLK6 as a prototype enzyme, we have developed an assay using a serine proteinase-targeted activity-based probe coupled to antibody capture. By employing activity-based labeling, we were able to quantify the proportion of enzymatically active relative to total immunoreactive KLK6 in crude cerebrospinal fluid from routine analyses and ascites fluid from ovarian cancer patients, as well as in supernatants from cancer cell lines. Our approach allowed monitoring of pro-KLK6 conversion to its active enzyme species and demonstrated that up to 5% of immunoreactive KLK6 detected in clinical samples represents active enzyme. We suggest that this new activity-based probe assay will prove of value as a complement to routine KLK immunoassay measurements for validating KLKs as cancer biomarkers.

scholarly journals DNA aptamer-based detection of prostate cancer

2015 ◽  
Vol 69 (1) ◽  
Author(s):  
Pawan Jolly ◽  
Nello Formisano ◽  
Pedro Estrela
Keyword(s):  
Prostate Cancer ◽  
Point Of Care ◽  
Specific Antigen ◽  
Analytical Techniques ◽  
Cost Effective ◽  
Dna Aptamer ◽  
Clinical Samples ◽  
Gradual Transition ◽  
Long Term Stability ◽  
Promising Tool

AbstractThe use of aptamers in biosensing has attracted considerable attention as an alternative to antibodies because of their unique properties such as long-term stability, cost-effectiveness and adjustability to various applications. Among cancers, the early diagnosis of prostate cancer (PCa) is one of the greatest concerns for ageing men worldwide. One of the most commonly used biomarkers for PCa is prostate-specific antigen (PSA), which can be found in elevated levels in patients with cancer. This review presents the gradual transition of research from antibody-based to aptamerbased biosensors, specifically for PSA. A brief description on aptamer-based biosensing for other PCa biomarkers is also presented. Special attention is given to electrochemical methods as analytical techniques for the development of simple, sensitive and cost-effective biosensors. The review also focuses on the different surface chemistries exploited for fabrication and their applications in clinical samples. The use of aptamers represents a promising tool for the development of point-ofcare biosensors for the early detection of prostate cancer. In view of the unmatched upper hand of aptamers, future prospects are also discussed, not only in the point-of-care format but also in other novel applications.

scholarly journals Performance of the 4Kscore Test in Plasma and Serum and Stability of the Component Analytes in Clinical Samples

2018 ◽  
Vol 3 (2) ◽  
pp. 185-199 ◽  
Author(s):  
Christina E Higgins ◽  
Patricia Neybold ◽  
Marcella B Holdridge ◽  
Catherine R Barnes ◽  
Yan Dong ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Specific Antigen ◽  
Clinical Information ◽  
Target Population ◽  
Clinical Samples ◽  
Free Psa ◽  
Total Prostate Specific Antigen ◽  
Edta Plasma ◽  
The Stability ◽  
Intact Psa

Abstract Background The 4Kscore Test determines a personalized risk score for aggressive prostate cancer by combining the blood sample measurements of total prostate-specific antigen (tPSA), free PSA (fPSA), intact PSA (iPSA), and human kallikrein-related peptidase 2 (hK2) with patient clinical information to generate the patient risk's score; thus, accuracy and precision of the 4Kscore depend on the reliability of these measurements. Although tPSA and fPSA are measured on a Food and Drug Administration (FDA)-approved platform, the performance of the iPSA and hK2 assays in the clinical setting has not previously been reported. Methods Analytical performance was determined for the iPSA and hK2 assays in both serum and EDTA plasma, according to Clinical and Laboratory Standards Institute guidelines. Equivalence of the 4Kscore in both sample matrices was demonstrated in a 353-patient clinical cohort, and the stability of endogenous iPSA and hK2 for at least 3 days was demonstrated in a smaller subset. Results Intralaboratory and interlaboratory precision of the iPSA and hK2 assays in both matrices was comparable with that of FDA-approved tPSA and fPSA assays (<18% for iPSA; <8% for hK2). The picogram per milliliter sensitivity and wide dynamic range of the iPSA and hK2 assays allowed for accurate measurements in the target population. The 4Kscore generated in either matrix up to 3 days after collection is equivalent to that measured within 24 h of collection (Passing–Bablok slope 95% CI: plasma, 0.999–1.034; serum, 0.997–1.040). Conclusions The robust performance of component assays and reliable stability of the endogenous analytes in clinical samples proven here ensures an accurate 4Kscore Test result.

The Multiple Active Enzyme Species of γ-Aminobutyric Acid Aminotransferase Are Not Isozymes

2000 ◽  
Vol 374 (2) ◽  
pp. 248-254 ◽  
Author(s):  
Yumee Kim Koo ◽  
Dhirendra Nandi ◽  
Richard B. Silverman
Keyword(s):  
Active Enzyme ◽  
Aminobutyric Acid ◽  
Enzyme Species

Prostate-specific antigen in serum occurs predominantly in complex with alpha 1-antichymotrypsin

1991 ◽  
Vol 37 (9) ◽  
pp. 1618-1625 ◽  
Author(s):  
H Lilja ◽  
A Christensson ◽  
U Dahlén ◽  
M T Matikainen ◽  
O Nilsson ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Monoclonal Antibodies ◽  
Serum Concentration ◽  
Prostate Specific Antigen ◽  
Proteinase Inhibitors ◽  
Specific Antigen ◽  
Serine Proteinase ◽  
Gel Chromatography ◽  
Extracellular Proteinase ◽  
Rabbit Igg

Abstract Immunologic measurements of the serum concentration of prostate-specific antigen (PSA), an abundant prostatic-secreted serine proteinase, are frequently used to monitor patients with prostate cancer, though it has not been ascertained whether this immunoreactivity represents a PSA zymogen, the active proteinase, or PSA complexed to extracellular proteinase inhibitors. To characterize the PSA immunoreactivity in serum, we used monoclonal antibodies produced against PSA and a polyclonal rabbit IgG against alpha 1-antichymotrypsin in the design of three noncompetitive PSA assays: assay T, which detected PSA both when present as the active proteinase and when complexed to alpha 1-antichymotrypsin; assay F, which recognized the active proteinase but most poorly detected PSA complexed to alpha 1-antichymotrypsin; and assay C, which was specific for PSA complexed to alpha 1-antichymotrypsin. We used the three assays to measure PSA immunoreactivity in 64 patients' sera and in the effluent after gel chromatography of sera from four patients. This identified an 80- to 90-kDa complex between PSA and alpha 1-antichymotrypsin as the predominant fraction of the PSA immunoreactivity in blood plasma; an immunoreactive 25- to 40-kDa compound was the minor fraction.

scholarly journals Immunofluorometric Assay of Human Kallikrein 10 and Its Identification in Biological Fluids and Tissues

2001 ◽  
Vol 47 (2) ◽  
pp. 237-246 ◽  
Author(s):  
Liu-Ying Luo ◽  
Linda Grass ◽  
David J C Howarth ◽  
Pierre Thibault ◽  
Huy Ong ◽  
...  
Keyword(s):  
Biological Fluids ◽  
Expression System ◽  
Specific Antigen ◽  
Cross Reactivity ◽  
Yeast Expression System ◽  
Disease States ◽  
Pichia Pastoris Yeast ◽  
Sandwich Type ◽  
Kallikrein 2 ◽  
Concentration Changes

Abstract Background: The human kallikrein 10 gene [KLK10, also known as normal epithelial cell-specific 1 gene (NES1)] is a member of the human kallikrein gene family. The KLK10 gene encodes for a secreted serine protease (hK10). We hypothesize that hK10 is secreted into various biological fluids and that its concentration changes in some disease states. The aim of this study was to develop a sensitive and specific immunoassay for hK10. Methods: Recombinant hK10 protein was produced and purified using a Pichia pastoris yeast expression system. The protein was used as an immunogen to generate mouse and rabbit polyclonal anti-hK10 antisera. A sandwich-type immunofluorometric assay was then developed using these antibodies. Results: The hK10 immunoassay has a detection limit of 0.05 μg/L. The assay is specific for hK10 and has no detectable cross-reactivity with other homologous kallikrein proteins, such as prostate-specific antigen (hK3), human glandular kallikrein 2 (hK2), and human kallikrein 6 (hK6). The assay was linear from 0 to 20 μg/L with within- and between-run CVs <10%. hK10 is expressed in many tissues, including the salivary glands, skin, and colon and is also detectable in biological fluids, including breast milk, seminal plasma, cerebrospinal fluid, amniotic fluid, and serum. Conclusions: We report development of the first immunofluorometric assay for hK10 and describe the distribution of hK10 in biological fluids and tissue extracts. This assay can be used to examine the value of hK10 as a disease biomarker.

scholarly journals Padlock Probe Assay for Detection and Subtyping of Seasonal Influenza

2018 ◽  
Vol 64 (12) ◽  
pp. 1704-1712 ◽  
Author(s):  
Felix Neumann ◽  
Iván Hernández-Neuta ◽  
Malin Grabbe ◽  
Narayanan Madaboosi ◽  
Jan Albert ◽  
...  
Keyword(s):  
Seasonal Influenza ◽  
Rolling Circle Amplification ◽  
High Specificity ◽  
Clinical Samples ◽  
Padlock Probe ◽  
Rolling Circle ◽  
Diagnostic Assays ◽  
Padlock Probes ◽  
Probe Assay ◽  
Digital Quantification

Abstract BACKGROUND Influenza remains a constant threat worldwide, and WHO estimates that it affects 5% to 15% of the global population each season, with an associated 3 to 5 million severe cases and up to 500000 deaths. To limit the morbidity and the economic burden of influenza, improved diagnostic assays are needed. METHODS We developed a multiplexed assay for the detection and subtyping of seasonal influenza based on padlock probes and rolling circle amplification. The assay simultaneously targets all 8 genome segments of the 4 circulating influenza variants—A(H1N1), A(H3N2), B/Yamagata, and B/Victoria—and was combined with a prototype cartridge for inexpensive digital quantification. Characterized virus isolates and patient nasopharyngeal swabs were used for assay design and analytical validation. The diagnostic performance was assessed by blinded testing of 50 clinical samples analyzed in parallel with a commercial influenza assay, Simplexa™ Flu A/B & RSV Direct. RESULTS The assay had a detection limit of 18 viral RNA copies and achieved 100% analytical and clinical specificity for differential detection and subtyping of seasonal circulating influenza variants. The diagnostic sensitivity on the 50 clinical samples was 77.5% for detecting influenza and up to 73% for subtyping seasonal variants. CONCLUSIONS We have presented a proof-of-concept padlock probe assay combined with an inexpensive digital readout for the detection and subtyping of seasonal influenza strains A and B. The demonstrated high specificity and multiplexing capability, together with the digital quantification, established the assay as a promising diagnostic tool for seasonal influenza.

scholarly journals Role of a novel race-related tumor suppressor microRNA located in frequently deleted chromosomal locus 8p21 in prostate cancer progression

2019 ◽  
Vol 40 (5) ◽  
pp. 633-642 ◽  
Author(s):  
Divya Bhagirath ◽  
Thao Ly Yang ◽  
Z Laura Tabatabai ◽  
Varahram Shahryari ◽  
Shahana Majid ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Tumor Suppressor ◽  
Cell Lines ◽  
Cancer Progression ◽  
Specific Antigen ◽  
Tumor Grade ◽  
Clinical Samples ◽  
Mesenchymal Transition ◽  
Microrna Genes

Abstract The prostate cancer (PCa) genome is characterized by deletions of chromosome 8p21–22 region that increase significantly with tumor grade and are associated with poor prognosis. We proposed and validated a novel, paradigm-shifting hypothesis that this region is associated with a set of microRNA genes—miR-3622, miR-3622b, miR-383—that are lost in PCa and play important mechanistic roles in PCa progression and metastasis. Extending our hypothesis, in this study, we evaluated the role of a microRNA gene located in chromosome 8p—miR-4288—by employing clinical samples and cell lines. Our data suggests that (i) miR-4288 is widely downregulated in primary prostate tumors and cell lines; (ii) miR-4288 expression is lost in metastatic castration-resistant PCa; (ii) miR-4288 downregulation is race-related PCa alteration that is prevalent in Caucasian patients and not in African Americans; (iii) in Caucasians, miR-4288 was found to be associated with increasing tumor grade and high serum prostate-specific antigen, suggesting that miR-4288 downregulation/loss may be associated with tumor progression specifically in Caucasians; (iv) miR-4288 possess significant potential as a molecular biomarker to predict aggressiveness/metastasis; and (v) miR-4288 is anti-proliferative, is anti-invasive and inhibits epithelial-to-mesenchymal transition; and (vi) miR-4288 directly represses expression of metastasis/invasion-associated genes MMP16 and ROCK1. Thus, the present study demonstrates a tumor suppressor role for a novel miRNA located with a frequently lost region in PCa, strengthening our hypothesis that this locus is causally related to PCa disease progression via loss of microRNA genes. Our study suggests that miR-4288 may be a novel biomarker and therapeutic target, particularly in Caucasians.

scholarly journals Laboratory Diagnostic Techniques for Entamoeba Species

2007 ◽  
Vol 20 (3) ◽  
pp. 511-532 ◽  
Author(s):  
R. Fotedar ◽  
D. Stark ◽  
N. Beebe ◽  
D. Marriott ◽  
J. Ellis ◽  
...  
Keyword(s):  
Entamoeba Histolytica ◽  
Diagnostic Tests ◽  
New Technologies ◽  
Specific Antigen ◽  
Gastrointestinal Symptoms ◽  
Public Health Problem ◽  
Intestinal Lumen ◽  
Molecular Diagnostic ◽  
Clinical Samples ◽  
Diagnostic Laboratory

SUMMARY The genus Entamoeba contains many species, six of which (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanni) reside in the human intestinal lumen. Entamoeba histolytica is the causative agent of amebiasis and is considered a leading parasitic cause of death worldwide in humans. Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms, there is still no convincing evidence of a causal link between the presence of these two species and the symptoms of the host. New approaches to the identification of E. histolytica are based on detection of E. histolytica-specific antigen and DNA in stool and other clinical samples. Several molecular diagnostic tests, including conventional and real-time PCR, have been developed for the detection and differentiation of E. histolytica, E. dispar, and E. moshkovskii in clinical samples. The purpose of this review is to discuss different methods that exist for the identification of E. histolytica, E. dispar, and E. moshkovskii which are available to the clinical diagnostic laboratory. To address the need for a specific diagnostic test for amebiasis, a substantial amount of work has been carried out over the last decade in different parts of the world. The molecular diagnostic tests are increasingly being used for both clinical and research purposes. In order to minimize undue treatment of individuals infected with other species of Entamoeba such as E. dispar and E. moshkovskii, efforts have been made for specific diagnosis of E. histolytica infection and not to treat based simply on the microscopic examination of Entamoeba species in the stool. The incorporation of many new technologies into the diagnostic laboratory will lead to a better understanding of the public health problem and measures to control the disease.

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