Usefulness of a newly developed high-speed polymerase chain reaction analysis system for the diagnosis of Clostridioides difficile infection.

INTRODUCTION: The incidence of Clostridioides difficile infection (CDI) has been continuously increasing and thereby became an important issue worldwide. Appropriate diagnosis, management, and infection control are required for patients with CDI. Enzyme immunoassay (EIA) is a widely used standard diagnostic tool for C. difficile-specific glutamate dehydrogenase (GDH) and C. difficile toxins (toxins A and B). However, the sensitivity of EIA in detecting C. difficile toxins has been reported to be relatively low, resulting in CDI underdiagnosis. Therefore, nucleic acid amplification tests (NAAT) are recently developed for higher sensitivity/specificity test. METHODS: In this study, a total of 279 stool samples submitted for CDI diagnosis were examined using an independently developed new high-speed polymerase chain reaction (PCR) device (PathOC RightGene, Metaboscreen). In parallel, results were compared with those of definitive diagnosis and conventional diagnostic methods (EIA, real-time PCR) to assess the inspection accuracy. RESULTS: PathOC RightGene showed high sensitivity (96.7%) and specificity (96.7%). Regarding the measurement time, C. difficile-specific and C. difficile toxin genes were simultaneously detected in approximately 25 min for one sample (including the preprocessing and measurement time). CONCLUSION: PathOC RightGene has been found to show both excellent sensitivity and rapidity and thus can be used for the reliable and early diagnosis, which are needed for the appropriate management of CDI.

Rapid detection assay of toxigenic Clostridioides difficile through PathOC RightGene, a novel high-speed polymerase chain reaction device.

Nucleic acid amplification tests for diagnosing Clostridioides difficile infections (CDI) are improving to become faster and more accurate. This study aimed to evaluate the accuracy of rapid detection of toxigenic C. difficile using the novel high-speed polymerase chain reaction (PCR) device, PathOC RightGene. These results were compared and evaluated with real-time PCR (qPCR) and enzyme immunoassays (EIA) kit. For this study, 102 C. difficile and 3 Clostridium species isolated from CDI patients were used. These C. difficile isolates were 85 toxigenic and 17 non-toxigenic strains. The results of qPCR served as a standard, and sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the PathOC Right Gene were 99.2%, 99.4%, 100%, 98.8%, and 99.3%, respectively. Turnaround time of qPCR and EIA was 85 and 30 minutes, whereas PathOC RightGene was only 25 minutes including DNA extraction. This novel high-speed PCR device detected toxigenic C. difficile rapidly and accurately.

Single-drop analysis of various proteases in a cancer cell lysate using a capillary-assembled microchip.

Single-drop analysis of two different real sample solutions (2 microL) while simultaneously monitoring the activity of two sets of ten different proteases on a single microfluidic device is presented. The device, called a capillary-assembled microchip (CAs-CHIP), is fabricated by embedding square glass sensing capillaries (reagent-release capillaries, RRC) in the polydimethylsiloxane (PDMS) lattice microchannel, and used for that purpose. First, the performance reliability was evaluated by measuring the fluorescence response of twenty caspase-3-sensing capillaries on a single CAs-CHIP, and a relative standard deviation of 1.5-8.2 (% RSD, n = 5 or 10) was obtained. This suggests that precise multiplexed protease-activity sensing is possible by using a single CAs-CHIP with multiple RRCs embedded. Then, using a single CAs-CHIP, real sample analysis of the activity of ten different caspases/proteases in cervical cancer (HeLa) cell lysate treated and untreated with the cell-death-inducer drug, doxorubicin, was simultaneously carried out, and a significant difference in enzyme activity between these two samples was observed. These results suggested the usefulness of the CAs-CHIP in the field of drug discovery.

"Drop-and-Sip" fluid handling technique for the reagent-release capillary (RRC)-based capillary-assembled microchip (CAs-CHIP): sample delivery optimization and reagent release behavior in RRC.

The experimental conditions of the sample delivery inside the reagent-release capillary-based capillary-assembled microchip (RRC-based CAs-CHIP) were optimized and the reagent release procedure in the RRC is discussed. Recently, our group introduced the basic concept of the "drop-and-sip" fluid handling technique (Anal. Chem., 2007, 79, 908). A microliter volume of sample solution is dropped on the inlet hole and is sipped into another hole, producing a sample plug flow in the main poly(dimethyl siloxane) (PDMS) channel, concurrently filling each sensing capillary that faces the main PDMS channel. However, the detailed evaluation of the successful sample delivery condition and the reagent release behavior in the RRC has not been fully discussed. Under our experimental conditions, ca. 0.6 - 2.4 s of sample plug-RRC contact time allowed the successful sample introduction into the RRC by capillary force without any reagent leakage or disturbance of the sample plug flow. On the other hand, reagent release behavior inside the RRC is governed by both convective and diffusive mass transport, which leads to a faster mixing time of the sample with reagents immobilized inside the RRC compared to that expected from the simple diffusion alone.

Development of a novel semi-quantitative analysis system for ultramicroscale samples by fluorescent capillary isoelectric focusing.

Microchemistry provides methods to analyze small quantities of chemical substances, including proteins, nucleic acids, and carbohydrates in various fields such as biomedical research, tissue engineering, molecular biology, and regeneration medicine. We therefore developed a fluorescent capillary isoelectric focusing (fluorescent cIEF) system for protein detection at an ultramicroscale volume, which aimed to isolate and identify, from a heterogeneous mixture of transduced cells, induced pluripotent stem cells (iPSCs) that could be fully reprogrammed. In addition, we demonstrated that the SOX2 protein, which is indispensable for the acquisition of pluripotency, could be detected by this new fluorescent cIEF system to identify iPSCs in the early phase of complete reprogramming. This method took less than 1 h for completion, including the time required for the antibody-antigen (Ab-Ag) reaction, and required as few as approximately three cells. Thus, this system could help improve iPSC generation as well as cut costs and reduce workloads.

Enzyme-release capillary as a facile enzymatic biosensing part for a capillary-assembled microchip.

A simple capillary enzymatic biosensor was developed. This was prepared by simply coating a dissolvable membrane containing enzyme/s on the inner wall of a square glass capillary. An easy measurement was carried out by capillary force sample introduction with concurrent enzyme release and a reaction with a certain substrate. Enzyme-release capillary (ERC) biosensors showed long-term storage stability of at least two weeks for a beta-galactoside derivative and glucose. Moreover, this could be integrated on a capillary-assembled microchip (CAs-CHIP) to broaden its multiple analyte sensing potential for clinical diagnostic applications.

Integration of multianalyte sensing functions on a capillary-assembled microchip: simultaneous determination of ion concentrations and enzymatic activities by a "drop-and-sip" technique.

A general and simple implementation of simultaneous multiparametric sensing in a single microchip is presented by using a capillary-assembled microchip (CAs-CHIP) integrated with the plural different reagent-release capillaries (RRCs), acting as various biochemical sensors. A novel "drop-and-sip" technique of fluid handling is performed with a microliter droplet of a model sample solution containing proteases (trypsin, chymotrypsin, thrombin, elastase) and divalent cations (Ca2+, Zn2+, Mg2+) that passes through the microchannel with the aid of a micropipette as a vacuum pump, concurrently filling each RRC via capillary force. To avert the evaporation of the nanoliter sample volume in each capillary, PDMS oil is dropped on the outlet hole of the CAs-CHIP exploiting the capillary force that results in spontaneous sealing of all the RRCs. In addition, this high-speed sample introduction alleviates the possibility of protein adsorption and capillary cross-contamination, allowing a reliable and multianalyte determination of a sample containing many different proteases and divalent cations by using the fluorescence image analysis. Presented results suggested the possible application of this microchip in the field of drug discovery and systems biology.

Multiple enzyme linked immunosorbent assay system on a capillary-assembled microchip integrating valving and immuno-reaction functions.

Multiple enzyme linked immunosorbent assay (ELISA) chip is developed by using capillary-assembled microchip (CAs-CHIP) technique, which involves simple embedding of 2-3mm length of square capillaries possessing valving and immuno-reaction functions into the microchannels fabricated on a PDMS substrate. In contrast to the previously reported ELISA chips, our system enables not only the flexible design of the multi-ELISA chip required for many different diagnostic purposes, but also the valving operation required for a reliable analysis. Here, a thermo-responsive polymer-immobilized capillary was used together with a small Peltier device, as a valving part, and different antibody-immobilized capillaries were used as immuno-reaction part. Sample solution and detecting reagent solutions were sequentially introduced through the valving capillary, and the valve is closed to completely stop the solution flow inside the immuno-reaction capillaries and detected using thermal lens microscope (TLM). Different anti-IgGs (human, goat, chicken) were immobilized and used as ELISA parts of CAs-CHIP. Sequential introductions of the mixed IgG solution, mixed enzyme-antibody solution and substrate solution facilitated the multiple determinations of 0.1 ng mL(-1) IgGs (human, goat, chicken) with total analysis time of about 30 min. The valve-integrated multi-ELISA chip developed here can be applied for many different diagnostic purposes by using different immuno-reaction capillaries necessary for a specific clinical diagnostic application.

Inhibition of proteasome activity by tyropeptin A in PC12 cells.

Tyropeptin A, a potent proteasome inhibitor not reported before, was produced by Kitasatospora sp. MK993-dF2. In this study, we investigated the effects of tyropeptin A on proteasome activity in PC12 cells. Tyropeptin A inhibited the intracellular proteasome activity in a dose-dependent way and seemed to cause neurite outgrowth. As expected, ubiquitinated proteins that should be substrates for the proteasome accumulated in cells treated with tyropeptin A. Hence, it appears that tyropeptin A can permeate into cells and there inhibit the intracellular proteasome activity.

Panepophenanthrin, from a mushroom strain, a novel inhibitor of the ubiquitin-activating enzyme.

Screening for inhibitors of the ubiquitin-proteasome pathway, considered to regulate important cellular events and linked to serious diseases as well, led to isolation of a new compound, panepophenanthrin, from the fermented broth of a mushroom strain, Panus rudis Fr. IFO 8994. This is the first inhibitor of the ubiquitin-activating enzyme, which is indispensable for the ubiquitin-proteasome pathway. The structure of panepophenanthrin was determined by NMR and X-ray crystallographic analyses as 1,3a,10-trihydroxy-10c-(3-hydroxy-3-methylbut-1-enyl)-5,5-dimethyl-1,2,3,3a,5,5a,8,9,10,10a,10b,10c-dodecahydro-4-oxa-2,3,8,9-diepoxyacephenanthrylen-7-one.