1 Sensors 2013, 13, ; doi: /s Article OPEN ACCESS sensors ISSN Selective Detection and Automated Counting of Fluorescently-Labeled Chrysotile Asbestos Using a Dual-Mode High-Throughput Microscopy (DM-HTM) Method Myoung-Ock Cho 1, Hyo Mi Chang 2, Donghee Lee 1,, Yeon Gyu Yu 2, Hwataik Han 3 and Jung Kyung Kim 3,4, * Department of Mechanical Engineering, Graduate School, Kookmin University, Jeongneung-ro 77, Seongbuk-gu, Seoul , Korea; s: (M.-O.C.); (D.L.) Department of Chemistry, Graduate School, Kookmin University, Jeongneung-ro 77, Seongbuk-gu, Seoul , Korea; s: (H.M.C.); (Y.G.Y.) School of Mechanical Systems Engineering, Kookmin University, Jeongneung-ro 77, Seongbuk-gu, Seoul , Korea; Department of Integrative Biomedical Science and Engineering, Graduate School, Kookmin University, Jeongneung-ro 77, Seongbuk-gu, Seoul , Korea Current address: Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, 1400 R street, Lincoln, NE 68588, USA. * Author to whom correspondence should be addressed; Tel.: ; Fax: Received: 16 February 2013; in revised form: 22 April 2013 / Accepted: 24 April 2013 / Published: 2 May 2013 Abstract: Phase contrast microscopy (PCM) is a widely used analytical method for airborne asbestos, but it is unable to distinguish asbestos from non-asbestos fibers and requires time-consuming and laborious manual counting of fibers. Previously, we developed a high-throughput microscopy (HTM) method that could greatly reduce human intervention and analysis time through automated image acquisition and counting of fibers. In this study, we designed a dual-mode HTM (DM-HTM) device for the combined reflection and fluorescence imaging of asbestos, and automated a series of built-in image processing commands of ImageJ software to test its capabilities. We used DksA, a chrysotile-adhesive protein, for selective detection of chrysotile fibers in the mixed dust-free suspension of crysotile and
2 Sensors 2013, amosite prepared in the laboratory. We demonstrate that fluorescently-stained chrysotile and total fibers can be identified and enumerated automatically in a high-throughput manner by the DM-HTM system. Combined with more advanced software that can correctly identify overlapping and branching fibers and distinguish between fibers and elongated dust particles, the DM-HTM method should enable fully automated counting of airborne asbestos. Keywords: asbestos; chrysotile; DksA; high-throughput microscopy; dual-mode imaging; reflection; fluorescence; image processing and analysis; automated counting 1. Introduction Asbestos is a type of silica compound comprised of microscopic bundles of silicate fibers that can easily become airborne . Asbestos has several advantages, including durability, heat resistance, and flame resistance; therefore, it has been used widely as a construction material. However, since it is reported that accumulation of asbestos in the body causes serious diseases such as lung cancer, malignant mesothelioma, and other respiratory symptoms, its use is prohibited in most developed countries. Despite regulations, asbestos contamination still remains to be a common problem and many people die from exposure to asbestos worldwide . There are several established methods to detect asbestos, including phase-contrast microscopy (PCM) , polarized microscopy (PLM) , X-ray diffraction analysis and transmission electron microscopy (TEM) . Although PCM is simple and cost-effective compared to other methods, it has some limitations. PCM cannot detect thin fibers with diameters less than 0.25 m due to a resolution limit, and it cannot clearly identify certain types of asbestos . However, asbestos fiber dimension is an important factor in determining respiratory disease risk. Both lung cancer and asbestosis have been strongly associated with exposure to thin asbestos fibers (<0.25 m) . In addition, the PCM method gives inaccurate results due to the subjective analysis of the operator. Relatively accurate methods, including EM, also require trained experts and expensive equipments. Thus, innovative techniques for detecting asbestos are being studied in many areas; for example, automated image analysis techniques to replace the conventional manual counting method have shown remarkable results. These methods are mostly based on the color dispersion of asbestos. Kawabata et al.  developed a qualitative asbestos detection method by modifying conventional methods, and they attempted to detect only asbestos fibers among many types of particles by using both color dispersion and shape information. The use of refraction phenomena or polarization also allows asbestos to be distinguished from other particles. Moriguchi et al.  and Nomoto et al.  attempted to automate the detection of asbestos by image matching, which uses dispersion staining to search for color changes between two images in order to identify the asbestos. However, due to the complicated process, their methods required enormous time for image processing and analysis, and inconspicuous color changes remained difficult to detect. An automated image acquisition system is another indispensable requirement for the development of automated airborne asbestos counting method. In our previous study , we developed a high-throughput microscopy (HTM) method and demonstrated the feasibility of automated image acquisition and
3 Sensors 2013, counting of asbestos-like fibers by comparing HTM results with conventional PCM. The proposed HTM method reduces the analysis time significantly from ~90 min to <5 min using a batch process executing a list of built-in commands of public domain freeware ImageJ, despite the fact that the field-of-view is enlarged by ~40-fold from mm 2 to mm 2. Accuracy of the HTM method was reasonably comparable to PCM when tested on Proficiency Analytical Testing (PAT) standard asbestos samples. A common limitation of the PCM and HTM methods, both of which are based on bright-field imaging, is their inability to distinguish asbestos from non-asbestos fibrous materials. In a recent study, Kuroda et al.  implanted a biotechnology into asbestos detection technique. They used DksA, a chrysotile-binding protein, to quantitatively detect chrysotile, based on a colorimetric method by using DksA-AP, and they also used DksA-GFP for fluorescence imaging. The same research group used a new protein, GatZ, to distinguish amosite and crocidolite, which are members of the amphibole mineral group, from chrysotile which belongs to the serpentine mineral group . These protein-based methods have distinct advantages of detecting specific types of asbestos over existing methods by tagging fluorescent dyes to those proteins bound to asbestos fibers. Mossman et al.  proposed that the biological effects from various kinds of asbestos fibers should be considered individually due to their different properties including chemical composition, morphology, and durability. Selective detection methods using specific proteins might solve these problems. Here, we aim to improve the selectivity of asbestos detection using the chrysotile-binding protein extracted by the recombinant protein production method together with a newly designed dual-mode high-throughput microscopy (DM-HTM) system, which can obtain both fluorescence and reflected light images by fast scanning of an asbestos sample slide followed by automated image processing and analysis based on ImageJ software for enumeration of the asbestos fibers. 2. Materials and Methods A fluorescent dye-tagging method was used for chrysotile visualization. Fluorescence imaging techniques of asbestos samples using fluorescent bio-probes have been basically developed by Kuroda et al.  and Ishida et al. . We used the DksA protein for HTM analysis to enhance the sensitivity and selectivity of detecting chrysotile asbestos, which has been widely used commercially in many countries. We also attempted automatic enumeration of chrysotile fibers tagged with a fluorescently-labeled protein as well as total fibrous materials in a high-throughput manner, by the DM-HTM device. The results of manual counting were compared with those from the automated analysis of asbestos images taken in both reflection and fluorescence modes Extraction of Chrysotile-Adhesive Protein DksA, comprised of 151 amino acids, is an -helical protein that can be divided into three distinct structural fragments. DksA is expected to bind to RNA polymerase (RNAP) and is required for control of rrna transcription by ppgpp in vivo . Genomic DNA from Escherichia coli (E. coli) was used as a template and amplified by the polymerase chain reaction (PCR) by using the primer set shown in Table 1. Amplified DNA fragments and the pet21- plasmid were digested with NheI and BamHI, respectively, and the DNA was inserted into the NheI and BamHI sites of pet21-. DNA inoculated
4 Sensors 2013, with the vector was transformed into DH5- competent cells and incubated for 16 h at 36 C on a Luria-Bertani (LB) agar plate. Table 1. A set of sequencing primers. Primer DksA-forward DksA-reverse DNA Sequence GGA ATT CGC TAG CAT GCA AGA AGG AAA CCG GAG CCG TTG GAT CCC CGC CAG CCA TCT GTT TTT CGC Recombinant DNA was extracted from the bacterial colony, and its sequence was identified. The recombinant DNA was transformed again into BL21 (DE3) cells and incubated for 16 h on an LB agar plate at 36 C. Some colonies were extracted and cultured in LB medium, followed by induction with 0.1 mm IPTG after growing up to 0.4 at OD 600. The transformed E. coli was lysed using a microfluidizer (M-110P; Microfluidics, Newton, MA, USA). The supernatant was collected following centrifugation at 10,000 g at 4 C for 20 min. We confirmed that the protein was expressed in the soluble form after separation on a 12% SDS-PAGE gel. The supernatant was also passed through a Ni-NTA His-tag affinity chromatography column (Clontech, Mountain View, CA, USA) and dialyzed using a commercial dialysis kit (20-kD Slide-A-Lyzer Dialysis Cassette; Thermo Scientific, Rockford, IL, USA). Figure 1(a) shows the overall process of recombinant protein production, whereas Figure 1(b,c) show the size and amount of the amplified DNA fragments and plasmid, respectively. Figure 1. The procedure for extraction of chrysotile-adhesive protein DksA. (a) A flow chart for recombinant protein production. (b) Amplified DNA fragment followed by polymerase chain reaction using E. coli genomic DNA (dotted circle: size = 453 bp). (c) pet21-α plasmid vector loaded on an agarose gel (dotted circle: size = 3~3.5 kbp).
5 Sensors 2013, Dual-Mode HTM Setup and Image Acquisition We modified the configuration of the HTM device partially so that the device could detect a fluorescence signal. Two linear stages (M-426A; Newport, Irvine, CA, USA) were cross-connected on an optical breadboard, and 2 linear actuators were connected to the stages to allow motion in the x- and y-directions. An objective lens (NT36-132; Edmund Optics, Barrington, NJ, USA) and a charge-coupled device (CCD) camera (IMB-20FT; imi tech, Anyang, Korea) were equipped on both sides of a 160 mm scope tube. A brightness-controllable, circular light-emitting diode (LED) was set around the objective. The epi-illumination configuration thus enabled HTM to acquire reflected light images of opaque asbestos samples with good contrast by reducing the background intensity. Several optical filters were added to the basic composition of HTM to allow fluorescence imaging. An emission filter (ET605/70m; Chroma, Bellows Falls, VT, USA) and a dichroic mirror (T565lpxr; Chroma) were used between the CCD camera and the scope tube, and an excitation filter (ET545/25x; Chroma) was added perpendicularly to the circular LED. A green LED (TouchBright X-3; Live Cell Instrument, Seoul, Korea) was used as a fluorescence light source so that the light filtered through the excitation filter excited the fluorescent dye on the asbestos and the emitted fluorescence could be detected. Figure 2 shows a schematic of our modified HTM device for dual-mode reflection and fluorescence imaging. Figure 2. A schematic of DM-HTM system for both reflection and fluorescence imaging. The stages were automatically controlled by an application software, Zaber Console (Zaber Technologies, Vancouver, Canada). We used a trigger system to acquire asbestos sample images automatically according to the motion of the stages, which traveled a preset distance in each direction every second. We used a custom-made signal conductor control box (Board Lab, Incheon, Korea) for this work. The signals from the stage actuators were sent to the CCD camera with 0.5 s delay time after amplified in the control box. The travel distance was set to 650 µm in the x-direction and 490 µm in the y-direction in accordance with the area of the display window in an image acquisition software (CamViewer; imi tech). After obtaining 108 reflection images within a slide sample in the area of 5 5 mm 2, fluorescence images were taken at the same locations with the green LED on.
6 Sensors 2013, Verification of Chrysotile-Adhesive Protein Three types of asbestos (chrysotile, amosite and crocidolite) were used to verify the adhesive property of the DksA protein. Two hundred microliters of dialyzed protein solution was mixed with 0.6 g of each asbestos sample under high salt conditions (100 mm NaCl), and the mixtures were incubated at 4 C for 30 min. Following centrifugation at 12,000 rpm for 1 min, the pellets were washed twice with phosphate-buffered saline. After boiling for 10 min, the lysates were separated on a 12% SDS-PAGE gel Detection of Fluorescently-Labeled Chrysotile Fibers We validated the performance of the fluorescence imaging mode of our modified HTM system using fluorescent beads (F8827; Invitrogen, Carlsbad, CA, USA) with a nominal diameter of 2 µm. We obtained the images of the fluorescent beads injected into the plastic sample chamber of known volume and counted them automatically using the image analysis software. The theoretical number of beads per milliliter can be estimated by the following mathematical formula: concentration of suspended beads (1) The purified protein was tagged with a fluorescent dye using a commercialized kit (Alexa Fluor 555 Protein Labeling Kit; Invitrogen) to visibly confirm the protein-bound asbestos. The concentration of dye-tagged protein was adjusted to 100 g/ml. Three types of asbestos samples (0.2 g each) were mixed with 5 L of dye-tagged protein in three sample tubes, while a second group of tubes was prepared as control asbestos samples mixed with pure dye without the protein. The sample tubes were incubated for 30 min after adding 100 mm NaCl to each tube to prevent nonspecific reactivity. Then the samples were washed three times with a washing buffer (0.1 M sodium carbonate, 1% Tween 80, and 1% polyethyleneimine), dropped on a slide glass, sealed with colorless nail-polish to avoid drying, and observed under a fluorescence microscope (BX51; Olympus, Tokyo, Japan). For quantitative analysis, the chrysotile sample suspension was serially diluted in four steps and three slides were prepared at each sample concentration. One hundred and eight images acquired at the individual slide in the reflection or fluorescence mode were analyzed to produce the total number of fibers, and an averaged value of three automatic counts was reported as fiber count per unit area. We also used mixed samples of chrysotile and amosite to assess the enhanced selectivity of our proposed method. The fluorescently-labeled chrysotile sample suspension with a concentration of 200 g/ml was serially diluted in four steps with an amosite suspension. We obtained both reflection and fluorescence images of the mixed asbestos samples using the DM-HTM device and enumerated fibers in each image automatically as described in the following section.
7 Sensors 2013, Image Processing and Analysis We used java-based public domain free software ImageJ (National Institutes of Health, Bethesda, MD, USA) as an image processing and analysis program and applied additional plugins to detect asbestos effectively. Several steps for image processing and analysis were applied to a stack of sample images in our previous study , such as Subtract Background, Auto Local Threshold, Smooth, and Analyze Particles. The irregularity of the background brightness in the image was reduced through the Subtract Background process, and we used Auto Local Threshold to correct background illumination by varying a window of radius r around the image. These images were set to 0 ~ in Circularity for the Analyze Particles process to detect fibers longer than 5 m with an aspect ratio 3 in accordance with the counting rules stated in NIOSH 7400 . The circularity defined as 4 (area/perimeter 2 ) is a function of the aspect ratio ( ), the ratio between the long axis and the short axis of the ellipse, as given below: In our previous study , the upper limit of the circularity was incorrectly set to 0.33 which corresponds to 7. Although we cannot exclude the possibility of omitting fibers with 3 < 7 in the automatic counting process, it would have not affected the result significantly because most asbestos samples used in our prior study had long and thin fibrous shapes with 7. Here we tried to enumerate all the fibers with 3 in line with the NIOSH 7400 method while excluding elliptical non-asbestos particles by setting a strict range of input parameter Size for the Analyze Particles process. In order to eliminate small-sized particles and large debris, Size, represented as pixel squares, was set according to the minimum and maximum area of asbestos in the images. We analyzed hundreds of both reflection and fluorescence images by running an in-house written macro which carried out a series of built-in commands consecutively to apply a pre-determined optimal set of parameters. The total fiber count can be converted into fiber density (f/mm 2 ) or fiber concentration (f/cc) for displaying results Manual Counts by A Human Researcher Automatic counting results from the DM-HTM method were compared with manual counts determined by a human researcher. Three slides were prepared at each concentration of serially diluted asbestos samples and images were taken at two areas per slide. A human researcher counted the total number of fibers in each set of 50 images out of 108 reflection images obtained in one area, and an average value of two manual counts was used for computing the fiber density. 3. Results and Discussion 3.1. Protein Expression We combined the chrysotile-adhesive protein, DksA, with the DM-HTM platform to enhance the efficiency of asbestos detection, and demonstrated that selective detection of chrysotile is feasible. Expression and purification of DksA protein were conducted according to the method reported by (2)
8 Sensors 2013, Kuroda et al. , with the following modifications. The optimized condition for protein expression was obtained as proved in Figure 3(a), which indicates that the sample in the Lane 2 incubated for 3 h at 37 C after 0.1 mm IPTG induction shows a greater protein yield. The protein was purified using Ni-NTA His-tag affinity chromatography and separated on a 12% SDS-PAGE gel. Figure 3. Purification of recombinant protein. (a) Result of IPTG induction test. Lane 1, before induction; Lane 2, 0.1 mm IPTG at 37 C for 3 h; Lane 3, 0.5 mm IPTG at 37 C for 3 h; Lane 4, protein marker (size = 24 kd); Lane 5, 0.1 mm IPTG at 18 C for 13 h; and Lane 6, 0.5 mm IPTG at 18 C for 13 h. (b) Results of protein purification. Lane 1 and Lane 3 are the first fractions of eluted protein through the purification column, and Lane 2 and Lane 4 are the third fractions. (c) Result of peptide mapping of the recombinant protein. (d) Verification of the properties of DksA adhered to chrysotile. Figure 3(b) shows an amount of DksA and its size having a purity more than 90%. After dialysis, the final purified protein was sent for N-terminal sequencing and the exact molecular weight was determined by MALDI-TOF, as shown in Figure 3(c). The size and the concentration of the protein were 20 kd and 2 µg/µl, respectively. We tested the protein against three types of asbestos chrysotile, amosite and crocidolite to check whether the purified protein bound only to chrysotile. The asbestos samples were incubated with the protein solution for 30 min and separated by boiling. After centrifugation, the supernatant was loaded onto a 12% SDS PAGE gel. Figure 3(d) shows the presence of DksA attached to the asbestos samples. Although the protein was slightly eluted from both amosite and crocidolite, it mostly bound to chrysotile, implying that the protein strongly and specifically attaches to the chrysotile fibers Selective Detection of Chrysotile by Fluorescence Imaging We also studied the properties of the protein bound to chrysotile through a conventional fluorescence microscopy. The three types of asbestos, chrysotile, amosite and crocidolite, were incubated with the
9 Sensors 2013, fluorescent dye-labeled DksA protein, and observed under the fluorescence microscope. A second control group of the asbestos samples incubated with the pure dye was also observed to check the nonspecific reactivity. Figure 4 shows the result of the fluorescently-labeled protein and asbestos binding assay. Amosite and crocidolite can be seen in the phase contrast mode (Figure 4(a,c)), but invisible in the fluorescence mode (Figure 4(b)). Chrysotile can be observed more clearly in the fluorescence mode without background noise as shown in Figure 4(b). Figure 4. Protein binding test performed for three types of asbestos samples. (a) Phase contrast and (b) fluorescence images (pseudo-colored red) of asbestos fibers tagged with fluorescently-labeled DksA protein. (c) Phase contrast and (d) fluorescence images of asbestos fibers treated with fluorescent dye only without DksA protein. Bar = 100 µm. Fluorescence signal was not detected in any type of asbestos samples incubated with pure dye solution (Figure 4(d)), indicating that there was no nonspecific reactivity by the fluorescent dye and that the DksA protein bound specifically to the chrysotile fibers. The phase-contrast and fluorescence images acquired with the conventional fluorescence microscopy can be used as reference images for subsequent comparison with reflection and fluorescence images obtained by the DM-HTM system. The specificity of DksA binding to chrysotile has also been tested against all five remaining types of asbestos as well as ten different kinds of non-asbestos fibers by Ishida et al. [13,16]. A further test was conducted to confirm the selectivity of the protein against chrysotile. We created mixed samples of chrysotile and amosite at different concentration ratios, and then observed them using the DM-HTM device. We acquired both reflected light images and fluorescence images of the
10 Sensors 2013, mixed asbestos sample at the same positions on the slide. The images of the mixed asbestos samples are displayed in Figure 5. Figure 5. Reflection and fluorescence images of mixed samples of chrysotile and amosite at various concentration ratios. Reflection (left column) and fluorescence images (right column; pseudo-colored red). Concentration ratio of chrysotile to amosite: (a) 200/0, (b) 100/100, (c) 50/150, and (d) 25/175 µg/ml. Bar = 100 µm. As the amount of chrysotile was decreased with the increasing amount of amosite, it was difficult to detect chrysotile in the reflection mode at low concentrations of chrysotile owing to the interference by amosite. However, it was straightforward to identify the chrysotile fibers in the fluorescence images Automated and High-Throughput Counting of Chrysotile Using DM-HTM Our DM-HTM device was able to acquire both reflection and fluorescence images consecutively at the same positions of the sample slide. Additional light source and fluorescence filters were added to the HTM device, and the scan pathway was changed to the regression mode in order to return to the position where the first reflection image was taken, and to start acquiring fluorescence images. The capabilities of the DM-HTM system were tested by running the macro that automates a series of
11 Sensors 2013, built-in commands and plugins provided by the ImageJ. Figure 6(a) shows the result of counting the serially diluted fluorescent microbeads. The slope of the linear regression line through the origin is 0.89 (R 2 = 0.99) denoting that the measured number of particles (N measured ) is about 10% less than the theoretical number of particles (N theory ), presumably due to sample loss during pipetting and uneven distribution of particles in the chamber. Chrysotile samples that were diluted in four steps were prepared to prove the possibility of enhancing the sensitivity of detecting asbestos fibers in the fluorescence mode. We acquired reflection images of highly diluted samples at low intensity level of illumination deliberately making the images have lower contrast. The results from the analysis of both reflection and fluorescence images by DM-HTM were compared with the results from the manual counting method described in Section 2.6 and presented in Figure 6(b). Manual count represents the total number of fibers enumerated from a set of 50 reflection images by a human researcher and is considered to be the gold standard in this study. Figure 6. Validation of serially diluted microbead and fiber counts by automated image processing and analysis. (a) Comparison of theoretical (N theory ) and measured (N measured ) numbers of microspheres in fluorescence mode of DM-HTM method. (b) Comparison of chrysotile asbestos fiber counts determined by DM-HTM and manual counting. According to the slopes of the linear regression lines in Figure 6(b), we found that the automatic counts from reflection and fluorescence image analyses were 10% less and 25% greater than the manual counts, respectively. Although neither method accurately reproduces the manual counting, the correlation with the manual counts is higher for the reflection image analysis. This difference could be caused by uncounted small fibers and fibers with low contrast against the background during manual and automatic analyses of the bright-field reflection images (not shown here). Those undetectable small and low contrast chrysotile fibers can be seen and identified more sensitively in the fluorescence images resulting in automatic counts biased by 25% from the manual counts. The extent of bias is not peculiar to the mode of imaging but dependent on the quality of sample images and image processing scheme as well. Therefore standardization of the testing procedures from sample preparation to image acquisition and analysis is necessary to reduce the bias or to render the bias reproducible. The contrast of detecting asbestos fibers in the bright-field mode can be greatly enhanced with a differential interference contrast microscopy as reported in a recent study .
12 Sensors 2013, We also evaluated our DM-HTM with mixed asbestos samples as described in Section 2.4. Representative reflection and fluorescence images of the mixed chrysotile and amosite are given in Figure 5. The contrast of the reflection images taken at normal illumination level is much higher than those used for Figure 6(b) and the background noise such as debris and air bubble is noticeable in some images (Figure 7(c)). Figure 7. Results from analyses of reflection and fluorescence images. (a) Automatic fiber counts of the mixed asbestos samples (chrysotile and amosite) against chrysotile concentrations. (b) Automatic fiber counts of chrysotile samples against chrysotile concentrations. Representative reflection image (c) with high background noise level and corresponding fluorescence image (pseudo-colored red) (d). Bar = 100 µm. Figure 7(a) shows the automatic counts of the mixed asbestos samples against chrysotile concentrations. Since the amosite concentration is inversely related with the chrysotile concentration and the size of amosite is much smaller than chrysotile in the mixed sample, the amount of amosite is greater than chrysotile. Therefore the total fiber count from the reflection image analysis is decreased with increasing chrysotile concentration. However, since only the chrysotile fibers are visible in the fluorescence mode, the number of fibers determined by fluorescence image analysis is directly proportional to the chrysotile concentration. Figure 7(b) shows the automatic counts of chrysotile samples against chrysotile concentrations. Reflection image analysis resulted in fluctuation and overestimation of the fiber counts in the sample slide where air bubbles were formed, by erroneously recognizing their menisci as fibers. In contrast, the fiber count from fluorescence image analysis is linearly increased with the chrysotile concentration regardless of background noise level in the sample slide. Non-fluorescent debris and bubble images appeared in the reflection image are removed completely in the fluorescence image as exhibited in Figure 7(c,d). This tendency to over count has not been considered in the existing PCM method that
13 Sensors 2013, is based on manual counting in bright-field mode by human naked eye. We may reveal and compensate those biased errors accompanied by manual counting through our DM-HTM method. We enhanced the sensitivity and selectivity of the HTM method to detect chrysotile exclusively from low-concentration samples containing small and thin fibers and asbestos of different types by the fluorescently-labeled chrysotile-adhesive protein and the DM-HTM system. In particular the background noise, which is often considered to be fibers in bright-field imaging mode, was reduced by approximately 90% in the fluorescence imaging mode. It was reported that chrysotile fibers that are as thin as nm can be detected using Cy3-labeled DksA protein . It is promising that the proposed DM-HTM method should realize fully automated counting of airborne asbestos if combined with more advanced software that can identify overlapping and branching fibers and distinguish between fibers and oval-shaped debris. 4. Conclusions We have improved the selectivity of asbestos detection by using the chrysotile-binding protein extracted by the recombinant protein production method together with our newly designed dual-mode high-throughput microscopy (DM-HTM) system. We demonstrated that our DM-HTM method can accomplish high-throughput identification and enumeration of fluorescently-labeled chrysotile fibers exclusively in the fluorescence imaging mode as well as total fibers in the reflection mode with fast scanning of asbestos sample slides followed by automated image processing and analysis. We also proved that the sensitivity is enhanced for the samples with tiny asbestos fibers that are not detected in low contrast bright-field images. The DM-HTM method can be improved substantially to enable the fully automated counting of airborne asbestos by combining with more advanced image processing technique that can correctly identify overlapping, cross-linking and branching fibers and properly differentiate fibers from elongated dust particles. Integration of DM-HTM with a new sampling and pretreatment procedure will extend the application of the protein-based method to on-site and real-time detection of airborne asbestos. Acknowledgments This research was supported by grants from the Converging Research Center Program (No. 2012K001383) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology, and also from the Human Resources Development Program (No ) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) funded by the Ministry of Knowledge Economy, Republic of Korea. Conflict of Interest The authors declare no conflict of interest. References 1. Perry, A. A Discussion of Asbestos Detection Techniques for Air and Soil; U.S. Environmental Protection Agency: Washington, DC, USA, 2004.
14 Sensors 2013, DCOMM. Asbestos in the workplace: a difficult legacy. World Work 2004, 50, Asbestos and Other Fibers by PCM: Method In NIOSH Manual of Analytical Methods (NMAM), 4th ed.; DHHS (NIOSH) Publication: Cincinnati, OH, USA, Asbestos (bulk) by PLM: Method In NIOSH Manual of Analytical Methods (NMAM), 4th ed.; DHHS (NIOSH) Publication: Cincinnati, OH, USA, Asbestos by TEM: Method In NIOSH Manual of Analytical Methods (NMAM), 4th ed.; DHHS (NIOSH) Publication: Cincinnati, OH, USA, Dement, J.M.; Wallingford, K.M. Comparison of phase contrast and electron microscopic methods for evaluation of occupational asbestos exposures. Appl. Occup. Environ. Hyg. 1990, 5, Stayner, L.; Kuempel, E.; Gilbert, S.; Hein, M.; Dement, J. An epidemiological study of the role of chrysotile asbestos fibre dimensions in determining respiratory disease risk in exposed workers. Occup. Environ. Med. 2008, 65, Kawabata, K.; Komori, Y.; Mishima, T.; Asama, H. An asbestos fiber detection technique utilizing image processing based on dispersion color. Part. Sci. Technol. 2009, 27, Moriguchi, Y.; Hotta, K.; Takahashi, H. Asbestos detection from microscope images using support vector random field of local color features. LNCS 2009, 5507, Nomoto, A.; Hotta, K.; Takahashi, H. An asbestos counting method from microscope images of building materials using summation kernel of color and shape. LNCS 2009, 5507, Cho, M.-O.; Yoon, S.; Han, H.; Kim, J.K. Automated counting of airborne asbestos fibers by a high-throughput microscopy (HTM) method. Sensors 2011, 11, Kuroda, A.; Nishimura, T.; Ishida, T.; Hirota, R.; Nomura, K. Detection of chrysotile asbestos by using a chrysotile-binding protein. Biotechnol. Bioeng. 2008, 99, Ishida, T.; Alexandrov, M.; Nishimura, T.; Minakawa, K.; Chihirota, R.; Sekiguchi, K.; Kohyama, N.; Kuroda, A. Selective detection of airborne asbestos fibers using protein-based fluorescent probes. Environ. Sci. Technol. 2010, 44, Mossman, B.T.; Bignon, J.; Corn, M.; Seaton, A.; Gee, J.B. Asbestos: Scientific developments and implications for public policy. Science 1990, 247, Perederina, A.; Svetlov, V.; Vassylyeva, M.N.; Tahirov, T.H.; Yokoyama, S.; Artsimovitch, I.; Vassylyev, D.G. Regulation through the secondary channel-structural framework for ppgpp-dksa synergism during transcription. Cell 2004, 118, Ishida, T.; Alexandrov, M.; Nishimura, T.; Minakawa, K.; Hirota, R.; Sekiguchi, K.; Kohyama, N.; Kuroda, A. Evaluation of sensitivity of fluorescence-based asbestos detection by correlative microscopy. J. Fluoresc. 2012, 22, Zarubiieva, I.; Hwang, G.B.; Lee, J.S.; Bae, G.-N.; Oh, Y.-M.; Park, S.-W.; Lee, T.J.; Lee, H.J.; Woo, D.H.; Lee, S.; et al. Asbestos imaging and detection with differential interference contrast microscopy. Aerosol Air Qual. Res. 2013, 13, by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).
Aerosol and Air Quality Research, 13: 1145 1150, 2013 Copyright Taiwan Association for Aerosol Research ISSN: 1680-8584 print / 2071-1409 online doi: 10.4209/aaqr.2012.04.0094 Asbestos Imaging and Detection
Asbestos Presence in a Factory that Produced Asbestos-Containing Products Hana Fajkovi Department of Geology, Faculty of Science, University of Zagreb, Horvatovac 95, 10000 Zagreb, Croatia, e-mail: (email@example.com)
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Real-Time PCR Vs. Traditional PCR Description This tutorial will discuss the evolution of traditional PCR methods towards the use of Real-Time chemistry and instrumentation for accurate quantitation. Objectives
PATHOGEN DETECTION SYSTEMS BY REAL TIME PCR Results Interpretation Guide Pathogen Detection Systems by Real Time PCR Microbial offers real time PCR based systems for the detection of pathogenic bacteria
Essentials of Real Time PCR About Real-Time PCR Assays Real-time Polymerase Chain Reaction (PCR) is the ability to monitor the progress of the PCR as it occurs (i.e., in real time). Data is therefore collected
Western Blot Analysis with Cell Samples Grown in Channel-µ-Slides Polyacrylamide gel electrophoresis (PAGE) and subsequent analyses are common tools in biochemistry and molecular biology. This Application
Influence of Fiber Type, Size, and Number in Human Disease: Conclusions from Fiber Burden Analysis Andrew Churg, MD Department of Pathology University of British Columbia Vancouver, BC, Canada Techniques,
HIS-Select Nickel Affinity Gel Catalog Number P6611 Storage Temperature 2 8 C TECHNICAL BULLETIN Product Description HIS-Select Nickel Affinity Gel is an immobilized metalion affinity chromatography (IMAC)
Lab 10: Bacterial Transformation, part 2, DNA plasmid preps, Determining DNA Concentration and Purity Today you analyze the results of your bacterial transformation from last week and determine the efficiency
Integrated Protein Services Custom protein expression & purification Version DC04-0012 Expression strategy The first step in the recombinant protein generation process is to design an appropriate expression
Integrated Protein Services Custom protein expression & purification Last date of revision June 2015 Version DC04-0013 www.iba-lifesciences.com Expression strategy The first step in the recombinant protein
To make Glycerol Stocks of Plasmids ** To be done in the hood and use RNase/DNase free tips** 1. In a 10 ml sterile tube add 3 ml autoclaved LB broth and 1.5 ul antibiotic (@ 100 ug/ul) or 3 ul antibiotic
National Institute of Standards & Technology Certificate Standard Reference Material 1866b Common Commercial Asbestos This standard reference material (SRM) is comprised of three commercial-grade asbestos
ab185916 Hi-Fi cdna Synthesis Kit Instructions for Use For cdna synthesis from various RNA samples This product is for research use only and is not intended for diagnostic use. Version 1 Last Updated 1
Protocol for Cloning GFP into Mammalian cells Studiepraktik 2013 Molecular Biology and Molecular Medicine Aarhus University Produced by the instructors: Tobias Holm Bønnelykke, Rikke Mouridsen, Steffan
Common Course Topics Biology 1414: Introduction to Biotechnology I Assumptions Students may be enrolled in this course for several reasons; they are enrolled in the Biotechnology Program, they need a science
BIOTECHNOLOGY Levels: 11-12 Units of Credit: 1.0 CIP Code: 51.1201 Prerequisite: Biology or Chemistry Skill Certificates: #708 COURSE DESCRIPTION is an exploratory course designed to create an awareness
292PR 01 G-Biosciences 1-800-628-7730 1-314-991-6034 firstname.lastname@example.org A Geno Technology, Inc. (USA) brand name Classic Immunoprecipitation Utilizes Protein A/G Agarose for Antibody Binding (Cat.
Introduction To Real Time Quantitative PCR (qpcr) SABiosciences, A QIAGEN Company www.sabiosciences.com The Seminar Topics The advantages of qpcr versus conventional PCR Work flow & applications Factors
Bacterial Transformation and Plasmid Purification Chapter 5: Background History of Transformation and Plasmids Bacterial methods of DNA transfer Transformation: when bacteria take up DNA from their environment
Protocol for GenomePlex Whole Genome Amplification from Formalin-Fixed Parrafin-Embedded (FFPE) tissue Application Guide... 2 I. Description... 2 II. Product Components... 2 III. Materials to be Supplied
Analysis of Asbestos in Soil Hazel Davidson Technical Marketing Manager Diversity of asbestos materials Methods of analysis Problems and issues The way forward Types of asbestos: Chrysotile (white), Amosite
Product Manual Rapid GST Inclusion Body Solubilization and Renaturation Kit Catalog Number AKR-110 FOR RESEARCH USE ONLY Not for use in diagnostic procedures Introduction Bacteria are widely used for His
THE His Tag Antibody, mab, Mouse Cat. No. A00186 Technical Manual No. TM0243 Update date 01052011 I Description.... 1 II Key Features. 2 III Storage 2 IV Applications.... 2 V Examples - ELISA..... 2 VI
Page 1 of 6 skip navigational links This is an archive page. The links are no longer being updated. Statement by Gregory R. Wagner, M.D. Director, Division of Respiratory Disease Studies National Institute
RealStar HBV PCR Kit 1.0 11/2012 RealStar HBV PCR Kit 1.0 For research use only! (RUO) Product No.: 201003 96 rxns INS-201000-GB-02 Store at -25 C... -15 C November 2012 altona Diagnostics GmbH Mörkenstraße
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APPLICATION NOTE Real-Time PCR Real-time PCR: Understanding C t Real-time PCR, also called quantitative PCR or qpcr, can provide a simple and elegant method for determining the amount of a target sequence
CLONING IN ESCHERICHIA COLI Introduction: In this laboratory, you will carry out a simple cloning experiment in E. coli. Specifically, you will first create a recombinant DNA molecule by carrying out a
Expression and Purification of Recombinant Protein in bacteria and Yeast Presented By: Puspa pandey, Mohit sachdeva & Ming yu DNA Vectors Molecular carriers which carry fragments of DNA into host cell.
ab185915 Protein Sumoylation Assay Ultra Kit Instructions for Use For the measuring in vivo protein sumoylation in various samples This product is for research use only and is not intended for diagnostic
Introduction pglo Bacterial Transformation Biotechnology refers to technology used to manipulate DNA. The procedures are often referred to as genetic engineering. DNA is the genetic material of all living
BIODIVERSITY I BIOL1051 Microscopy Professor Marc C. Lavoie email@example.com MAJOR FUNCTIONS OF MICROSCOPES MAGNIFY RESOLVE: => INCREASE CONTRAST Microscopy 1. Eyepieces 2. Diopter adjustment
Genomic DNA Extraction Kit INSTRUCTION MANUAL Table of Contents Introduction 3 Kit Components 3 Storage Conditions 4 Recommended Equipment and Reagents 4 Introduction to the Protocol 4 General Overview
INSTRUCTION MANUAL ZymoPURE Plasmid Gigaprep Kit Catalog Nos. D4204 (Patent Pending) Highlights The fastest spin-column based procedure for purifying up to 10 mg of ultra-pure endotoxin-free transfection-grade
Lecture 13: DNA Technology DNA Sequencing Genetic Markers - RFLPs polymerase chain reaction (PCR) products of biotechnology DNA Sequencing determine order of nucleotides in a strand of DNA > bases = A,
Threshold and Analysis of Small Particles on the BD Accuri C6 Flow Cytometer Contents 2 Thresholds 2 Setting the Threshold When analyzing small particles, defined as particles smaller than 3.0 µm, on the
Endereço eletrônico http://www.atsdr.cdc.gov/asbestos/asbestos_whatis.html Search Index Home Glossary Contact Us CONTENTS Asbestos What Is Asbestos? Polarized Light Microscopy Slide of Asbestos Fibers.
Troubleshooting Sequencing Data Troubleshooting Sequencing Data No recognizable sequence (see page 7-10) Insufficient Quantitate the DNA. Increase the amount of DNA in the sequencing reactions. See page
Lecture 36: Basics of DNA Cloning-II Note: Before starting this lecture students should have completed Lecture 35 Sequential steps involved in DNA cloning using plasmid DNA as vector: Molecular cloning
Aurora Forensic Sample Clean-up Protocol 106-0008-BA-D 2015 Boreal Genomics, Inc. All rights reserved. All trademarks are property of their owners. http://www.borealgenomics.com firstname.lastname@example.org
ASBESTOS CONTROL PLAN POLICY It is the long term plan of Emily Carr University to have an asbestos free workplace. In the interim, The University plans to manage asbestos hazards based on prioritization
PowerFecal DNA Isolation Kit Catalog No. Quantity 12830-50 50 Preps Instruction Manual Inhibitor Removal Technology (IRT) is a registered trademark of MO BIO Laboratories, Inc. and is covered by the following
WESTERN BLOTTING TIPS AND TROUBLESHOOTING GUIDE TIPS FOR SUCCESSFUL WESTERB BLOTS TROUBLESHOOTING GUIDE 1. Suboptimal protein transfer. This is the most common complaint with western blotting and could
Microbiology Laboratory: MOLECULAR IDENTIFICATION OF UNKNOWN BACTERIA Classical Microbiology courses are typically structured to introduce the identification of bacterial species using a series of biochemical
Supplemental Text/Tables PCR Amplification and Sequencing PCR was carried out in a reaction volume of 20 µl using the ABI AmpliTaq GOLD kit (ABI, Foster City, CA). Each PCR reaction contained 20 ng genomic
Revision No.: ZJ0002 Issue Date: Aug 7 th, 2008 HBV Quantitative Real Time PCR Kit Cat. No.: HD-0002-01 For Use with LightCycler 1.0/LightCycler2.0/LightCycler480 (Roche) Real Time PCR Systems (Pls ignore
Application Note Separation of three monoclonal antibody variants using MCSGP Category Matrix Method Keywords Analytes ID Continuous chromatography, Biochromatography; FPLC Protein A-purified monoclonal
Cat. No. CS-330 Amount 1 Kit For in vitro use only. Quality guaranteed for 3 months. Store at 4 C. Application Screen for thermal stability of proteins as a function of the FUNDAMENTAL variables ph and
A Modified Wizard SV Genomic DNA Purification System Protocol to Purify Genomic DNA... A Modified Wizard SV Genomic DNA Purification System Protocol to Purify Genomic DNA from Shed Reptile Skin ABSTRACT
Identification and characterization of Verocytotoxin-producing Escherichia coli (VTEC) by Real Time PCR amplification of the main virulence genes and the genes associated with the serogroups mainly associated
Revised Fall 2011 The Techniques of Molecular Biology: Forensic DNA Fingerprinting The techniques of molecular biology are used to manipulate the structure and function of molecules such as DNA and proteins
Page 1 of 8 Purpose: To determine the concentration of infectious particles in an AAV vector sample. This process involves serial dilution of the vector in a TCID50 format and endpoint determination through
Quantum Prep Plasmid Miniprep Kit Instruction Manual Catalog #732-6100 For Technical Service Call Your Local Bio-Rad Office or in the U.S. Call 1-800-424-6723 Table of Contents Section 1 Introduction...
Page 1 of 7 Agencourt RNAdvance Cell v2 Total RNA Isolation from Cultured Cells Please refer to http://www.agencourt.com/technical for updated protocols and refer to MSDS instructions http://www.beckmancoulter.com/customersupport/msds/msds.asp
Bacterial Transformation with Green Fluorescent Protein pglo Version Table of Contents Bacterial Transformation Introduction..1 Laboratory Exercise...3 Important Laboratory Practices 3 Protocol...... 4
ChIP TROUBLESHOOTING TIPS Creative Diagnostics Abstract ChIP dissects the spatial and temporal dynamics of the interactions between chromatin and its associated factors CD Creative Diagnostics info@creative-
Product Manual Pure-IP Western Blot Detection Kit Catalog Number PRB-5002 20 blots FOR RESEARCH USE ONLY Not for use in diagnostic procedures Introduction The technique of immunoprecipitation (IP) is used
Introduction to Flow Cytometry presented by: Flow Cytometry y Core Facility Biomedical Instrumentation Center Uniformed Services University Topics Covered in this Lecture What is flow cytometry? Flow cytometer
Detection of Multiple Reporter Dyes in Real-time, On-line PCR Analysis with the LightCycler System Gregor Sagner, Cornelia Goldstein, and Rob van Miltenburg Roche Molecular Biochemicals, Penzberg, Germany
Nucleic Acid Purity Assessment using A 260 /A 280 Ratios A common practice in molecular biology is to perform a quick assessment of the purity of nucleic acid samples by determining the ratio of spectrophotometric
Supplemental Information (legend on next page) S1 Figure S1. Toehold Switch Design and First-Generation In Vivo Characterization, Related to Figure 1 (A) Trigger and switch plasmid copy number comparison.
ASBESTOS IN SETTLED DUST: A BRIEF REVIEW Background: Federal, State, and local asbestos regulations have established criteria for worker exposures, building occupancy, clearance levels, bulk sampling and