Dual-Mode Graphene Field-Effect Transistor Biosensor with Isothermal Nucleic Acid Amplification.

Despite a substantial increase in testing facilities during the pandemic, access remains a major obstacle, particularly in low-resource and remote areas. This constraint emphasizes the need for high-throughput potential point-of-care diagnostic tools in environments with limited resources. Loop-mediated isothermal amplification (LAMP) is a promising technique, but improvements in sensitivity are needed for accurate detection, especially in scenarios where the virus is present in low quantities. To achieve this objective, we present a highly sensitive detection approach of a dual-mode graphene-based field-effect transistor (G-FET) biosensor with LAMP. The G-FET biosensor, which has a transparent graphene microelectrode array on a glass substrate, detects LAMP products in less than 30 min using both observable color changes and Dirac point voltage measurements, even in samples with low viral concentrations. This dual-mode G-FET biosensor emerges as a potential alternative to conventional RT-PCR for severe acute respiratory syndrome-associated coronavirus (SARS-CoV)-2 detection or point-of-care testing, particularly in resource-constrained scenarios such as developing countries. Moreover, its capacity for colorimetric detection with the naked eye enhances its applicability in diverse settings.

Gold nanostructures modified carbon-based electrode enhanced with methylene blue for point-of-care COVID-19 tests using isothermal amplification.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) envelope (E) and RNA-dependent RNA polymerase (RdRP) genes were detected via electrochemical measurements using a screen-printed carbon electrode (SPCE) (3-electrode system) coupled with a battery-operated thin-film heater based on the loop-mediated isothermal amplification (LAMP) technique. The working electrodes of the SPCE sensor were decorated with synthesized gold nanostars (AuNSs) to obtain a large surface area and improve sensitivity. The LAMP assay was enhanced using a real-time amplification reaction system to detect the optimal target genes (E and RdRP) of SARS-CoV-2. The optimized LAMP assay was performed with diluted concentrations (from 0 to 109 copies) of the target DNA using 30 µM of methylene blue as a redox indicator. Target DNA amplification was conducted for 30 min at a constant temperature using a thin-film heater, and the final amplicon electrical signals were detected based on cyclic voltammetry curves. Our electrochemical LAMP analysis of SARS-CoV-2 clinical samples showed an excellent correlation with the Ct value of real-time reverse transcriptase-polymerase chain reaction, indicating successful validation of results. A linear relationship between the peak current response and the amplified DNA was observed for both genes. The AuNS-decorated SPCE sensor with the optimized LAMP primer enabled accurate analysis of both SARS-CoV-2-positive and -negative clinical samples. Therefore, the developed device is suitable for use as a point-of-care test DNA-based sensor for the diagnosis of SARS-CoV-2.

Effect of Back-Channel Surface on Reliability of Solution-Processed In0.51Ga0.15Zn0.34O Thin-Film Transistors with Thin Active Layer.

We have investigated the degradation mechanism of solution-processed indium-gallium-zinc-oxide (IGZO) thin-film transistors. The threshold voltage shift (ΔVth) followed a linear function under negative gate bias stress (NBS), while it showed a stretched-exponential behavior under positive gate bias stress. The slope of ΔVth for stress time was rarely changed with variations below 0.3 mV/s. The thickness of the fabricated IGZO layer (In0.51Ga0.15Zn0.34O) was approximately 10 nm. The Debye length (LD) was larger than IGZO thickness (tIGZO) due to the fully depleted active layer under NBS. Therefore, the degradation phenomenon under NBS was related to the adsorption at back-channel surface. The back-channel surface could be affected by the gate bias under NBS, and the molecules adsorbed at the IGZO layer were positively charged and induced extra electrons by NBS. We verified that the number of positively charged adsorbates had a proportional relationship with the ΔVth based on the two-dimensional technology computer-aided design (TCAD) simulation. Furthermore, we investigated the degradation phenomenon with the ΔVth equation regarding the adsorbates, and the result confirmed that the adsorption process could cause the linear ΔVth. We experimentally confirmed the effect of back-channel surface by comparing the ΔVth between different atmospheric conditions and LD. Consequently, the reaction at the back-channel surface should be considered to develop the metal-oxide semiconductor devices.

Primary pleural epithelioid angiosarcoma manifesting as a loculated hemothorax: A case report and literature review focusing on CT findings.

Primary pleural angiosarcoma (PPA) is an extremely rare and clinically aggressive tumor. We report the case of a 66-year-old man having PPA with chest computed tomography (CT) scan showing a large oval-shaped, nonenhancing high attenuation cystic mass in the left hemithorax. Morphological and immunohistochemical findings supported the diagnosis of epithelioid angiosarcoma. Pleural angiosarcoma should be considered in the differential diagnosis of spontaneous hemothorax manifesting as high attenuation loculated pleural fluid on CT.

A Graphene-Based Enzymatic Biosensor Using a Common-Gate Field-Effect Transistor for L-Lactic Acid Detection in Blood Plasma Samples.

Lactate is an important organic molecule that is produced in excess during anaerobic metabolism when oxygen is absent in the human organism. The concentration of this substance in the body can be related to several medical conditions, such as hemorrhage, respiratory failure, and ischemia. Herein, we describe a graphene-based lactate biosensor to detect the concentrations of L-lactic acid in different fluids (buffer solution and plasma). The active surface (graphene) of the device was functionalized with lactate dehydrogenase enzyme using different substances (Nafion, chitosan, and glutaraldehyde) to guarantee stability and increase selectivity. The devices presented linear responses for the concentration ranges tested in the different fluids. An interference study was performed using ascorbic acid, uric acid, and glucose, and there was a minimum variation in the Dirac point voltage during detection of lactate in any of the samples. The stability of the devices was verified at up to 50 days while kept in a dry box at room temperature, and device operation was stable until 12 days. This study demonstrated graphene performance to monitor L-lactic acid production in human samples, indicating that this material can be implemented in more simple and low-cost devices, such as flexible sensors, for point-of-care applications.

Sensitive electrochemical biosensor combined with isothermal amplification for point-of-care COVID-19 tests.

We report an electrochemical biosensor combined with recombinase polymerase amplification (RPA) for rapid and sensitive detection of severe acute respiratory syndrome coronavirus 2. The electrochemical biosensor based on a multi-microelectrode array allows the detection of multiple target genes by differential pulse voltammetry. The RPA reaction involves hybridization of the RPA amplicon with thiol-modified primers immobilized on the working electrodes, which leads to a reduction of current density as amplicons accumulate. The assay results in shorter "sample-to-answer" times than conventional PCR without expensive thermo-cycling equipment. The limits of detection are about 0.972 fg/µL (RdRP gene) and 3.925 fg/µL (N gene), which are slightly lower than or comparable to that of RPA assay results obtained by gel electrophoresis without post-amplification purification. The combination of electrochemical biosensors and the RPA assay is a rapid, sensitive, and convenient platform that can be potentially used as a point-of-care test for the diagnosis of COVID-19.

High-Resolution Magnetic Resonance Imaging Findings of Reversible Cerebral Vasoconstriction Syndrome associated with Severe Anemia: A Case Report.

Ischemic stroke is one of the manifestations of reversible cerebral vasoconstriction syndrome (RCVS). Many precipitants and associated disorders of RCVS have been suggested. However, few case reports have indicated an association between anemia and RCVS. Here, we report a case of a 66-year-old female with severe iron deficiency anemia (IDA), who presented with ischemic stroke and cerebral vasoconstriction, which gradually improved with conservative treatment. High-resolution vessel wall magnetic resonance imaging findings and reversibility suggested the possibility of RCVS. In patients with RCVS and ischemic stroke, IDA should be considered. Prompt management should be delivered to prevent disease progression and recurrence.

Leiomyosarcoma of the Sigmoid Colon Causing Sigmoido-Rectal Intussusception: A Case Report.

The most common malignant tumors in the colon are adenocarcinomas, while leiomyosarcoma (LMS) are rare. Here, we report a case of LMS of the sigmoid colon in a 73-year-old man who presented with sigmoido-rectal intussusception, which was discovered by abdominal computed tomography. As LMS of the colon is uncommon and is rarely associated with intussusception, we have described the imaging features in this case report.

Surveillance assessment for veterinary biocidal products in Korea: A laboratory investigation.

Veterinary biocides used in animal husbandry have the potential to cause human health concerns. Biocidal products for veterinary use, which contain pesticides approved in Korea, comprise 49 active ingredients within 234 products. Within 17 of these products there are 3 ingredients which are highly hazardous pesticides: coumaphos, dichlorvos and methomyl. In this study, the content of the active ingredients of 160 products sold domestically was investigated. Samples were collected for 119 biocidal products for veterinary use. These were analysed by high-performance liquid chromatography (HPLC) and gas chromatography (GC). Seventeen products were noncompliant (insufficient or excess quantity of active ingredients). The ingredients that were below the stated concentrations were amitraz, chlorpyrifos-methyl, cypermethrin, cyromazine, dichlorvos, fipronil, muscamone and trichlorfon. The ingredients that exceeded the stated concentrations were abamectin, fluvalinate and pyriproxyfen. The noncompliance rate in biocidal products for veterinary use was 9.19%. The results of this study show that three highly hazardous pesticides (coumaphos, dichlorvos and methomyl) and 10 active ingredients (abamectin, amitraz, chlorpyrifos-methyl, cypermethrin, cyromazine, fipronil, fluvalinate, muscamone, pyriproxyfen and trichlorfon) deviated from the stated concentrations. Thus, management plans should be established to ensure compliant veterinary drugs by post-distribution quality control, such as planning for regular inspection.

All-solution-processed colour-tuneable tandem quantum-dot light-emitting diode driven by AC signal.

We demonstrate a novel structure for a quantum-dot light-emitting diode (QD-LED) with wide-range colour-tuneable pixels, fabricated via full solution processing. The proposed device has a symmetrical structure produced via stacking of an inverted-structure diode with a green QD emission layer (EML) and normal-structure diode with a red QD EML. It is an electron-only device; however, a charge generation layer in the middle of the device generates holes for the formation of excitons. Depending on the polarity of the applied voltage, either the bottom inverted unit or the top normal unit is operated, thereby emitting green or red light, respectively. The working mechanism of the device is investigated via analysis of the charge generation mechanism and carrier transport path. In addition, the colour tunability is verified using a simple alternating current (AC) driving scheme; the duty cycle modulation of the AC signal enables fine colour adjustment over a broad range, from pure green to pure red. Thus, our colour-tuneable QD-LED with vertically stacked independently operated sub-pixels can open a promising pathway towards cost-effective ultra-high-resolution displays.

Rapid Determination of Benzylpenicillin Resistance in Staphylococcus aureus Bacteraemia Model.

Rapid determination of antimicrobial susceptibility/resistance is an important factor in selecting an appropriate antimicrobial treatment and eradicating infections promptly. Conventional antimicrobial susceptibility tests (ASTs) are very time consuming. Thus, we developed a liquid chromatography-mass spectrometry (LC-MS/MS) method for rapidly determining the resistance of Staphylococcus aureus to penicillin-G in an animal-infection model. This technique will be able to detect those resistant strains whose resistance mechanism specifically controlled by penicillinase. The resistance status of S. aureus against penicillin-G was determined by conventional AST. Cultured S. aureus cells were inoculated to chicken for developing bacteraemia. The solution of penicillin-G was intravenously administered (10 mg/kg b.w.) to chickens just after infection detection. Blood samples were collected at different intervals after drug administration. The concentration of active penicillin-G and its metabolites were determined from the bacteria-free blood supernatant by utilizing the LC-MS/MS method. Evidence of infection in chicken was observed within 5 h of bacterial inoculation. The penicillinase enzyme generated by S. aureus transforms the active penicillin-G to an inactive metabolite by hydrolysis, which is evident by the mass shift from 335.10600 to 353.11579 Da as quantified using liquid chromatography quadrupole time-of-flight mass spectrometry (LC/Q-TOF/MS). The signal intensity of inactive/hydrolysed penicillin-G is several-fold greater than that of the active penicillin-G in the blood sample of chicken infected with resistant strain and treated with penicillin-G. The antimicrobial resistance index (ARI) value of resistant S. aureus strain was more than 1, demonstrating the penicillin-G-resistance pattern of that strain. This method is able to determine the extent of ß-lactam antimicrobial resistance within 1.5 h from the patient's blood and is complementary with those existing AST methods which are usually practicing in the evaluation of ß-lactam antibiotic resistance.

Novel Nasal Epithelial Cell Markers of Parkinson's Disease Identified Using Cells Treated with α-Synuclein Preformed Fibrils.

Parkinson's disease (PD) is the most common neurodegenerative movement disorder, characterized by olfactory dysfunction in the early stages. α-Synuclein pathologies in the olfactory organs are shown to spread to the brain through the nose-brain axis. We first developed a nasal epithelial PD cellular model by treating RPMI-2650 cells with α-synuclein preformed fibrils (PFF). Upon uptake of PFF, RPMI-2650 cells showed mitochondrial proteome alteration and downregulation of parkin, which has previously been identified as a nasal biomarker of PD. Functional cluster analysis of differentially expressed genes in RPMI-2650 cells revealed various pathways affected by α-synuclein pathology, including the detection of chemical stimulus involved in sensory perception, olfactory receptor activity, and sensory perception of smell. Among genes that were most affected, we validated, by real-time quantitative PCR, the downregulation of MAP3K8, OR10A4, GRM2, OR51B6, and OR9A2, as well as upregulation of IFIT1B, EPN1, OR1D5, LCN, and OTOL1 in PFF-treated RPMI-2650 cells. Subsequent analyses of clinical samples showed a downregulation of OR10A4 and OR9A2 transcripts and an upregulation of IFIT1B in cells isolated from the nasal fluid of PD patients, as compared to those from the controls (cutoff value = 0.5689 for OR9A2, with 72.4% sensitivity and 75% specificity, and 1.4658 for IFIT1B, with 81.8% sensitivity and 77.8% specificity). Expression levels of these nasal PD markers were not altered in nasal fluid cells from SWEDD (scans without evidence of dopaminergic deficits) patients with PD-like motor symptoms. These nasal markers were significantly altered in patients of PD with hyposmia compared to the control hyposmic subjects. Our results validated the α-synuclein-treated nasal epithelial cell model to identify novel biomarkers for PD and suggest the utility of olfactory transcripts, along with olfactory dysfunction, in the diagnosis of PD.

Monitoring the hemostasis process through the electrical characteristics of a graphene-based field-effect transistor.

Graphene-based transistors are promising devices in the evaluation of carrier density in biological analytes. We report on the design and fabrication of a graphene-based field-effect transistor for monitoring and assessing the interaction between the coagulation factors based on the charge carrier density in a blood sample. When biochemical reactions occurred during the coagulation cascade process, a dopant effect was noticed on the graphene surface by the change in Dirac point voltage values. Additional experiments were performed using blood samples treated with activators (vitamin K, calcium chloride, and thromboplastin reagent) and inhibitors (heparin drugs) to evaluate the selectivity of the graphene field-effect transistor devices. Since the transfer characteristic curves presented divergent behaviours for different levels of procoagulants and anticoagulants, the measurements showed that the devices can assess changes in the concentrations of factors that inhibit or accelerate the cascade process when using untreated and treated samples. Reproducibility was verified by testing samples from different sources. To the best of our knowledge, this study is the first to demonstrate the potential of graphene in monitoring the hemostasis process through the analysis of the electrical properties of human whole blood.

Evaluation of Quality Control Methods for Foot-And-Mouth Disease Vaccines by High-Performance Liquid Chromatography.

Foot-and-mouth disease (FMD) is considered one of the highly contagious viral infections affecting livestock. In Korea, an FMD vaccination policy has been implemented nationwide since 2010 for the prevention and control of FMD. Since the vaccines are imported from various countries, standardized quality control measures are critical. In this study, we aimed to validate a high-performance liquid chromatography (HPLC) device in the Animal and Plant Quarantine Agency lab and identify an appropriate FMD vaccine pretreatment method for HPLC-a simple, reliable, and practical method to measure antigen content. Based on the analyses of specificity, linearity, accuracy, repeatability, intermediate precision, limits of detection, and limits of quantification using FMD standard samples, we validated the method using a standard material. Overall, we confirmed that the HPLC technique is effective for the quantitative assessment of the FMD virus 146S antigen in Korea. Using commercial FMD vaccines, we evaluated three separation methods and identified the method using n-pentanol and trichloroethylene as optimal for HPLC analysis. Our HPLC method was effective for the analytical detection of the antigen content in FMD vaccine, and it may be useful as a reference method for national lot-release testing.

Effects of Corrosion on Mechanical Properties of Welded Carbon Steel Pipe in District Heating Water.

This study examined the effect of corrosion on mechanical properties of welded carbon steel pipe in district heating water. To evaluate the corrosion properties, potentiodynamic tests were conducted and a galvanostatic test was used to accelerate corrosion. Tensile tests and microstructure observations were performed to figure out the degradation of the corroded region, and stress intensity factors were calculated. As a result of the potentiodynamic tests, welded carbon steel pipe showed uniform corrosion and the total charge was calculated. Using the galvanostatic test, the current density at the equivalent aging time was applied to the specimens. The tensile tests showed that according to corrosion damages, mechanical properties were degraded due to corrosion. Through the microstructure observations and calculations of stress intensity factors, the corrosion of the welded carbon steel pipe induced the degradation of mechanical properties. The mode of fracture was changed from ductile to brittle fracture with increasing aging time.

Biomechanical influence of lateral meniscal allograft transplantation on knee joint mechanics during the gait cycle.

BACKGROUND: This study evaluated the influence of meniscal allograft transplantation (MAT) on knee joint mechanics during normal walking using finite element (FE) analysis and biomechanical data. METHODS: The study included 20 patients in a transpatellar group and 25 patients in a parapatellar group. Patients underwent magnetic resonance imaging (MRI) evaluation after lateral MAT as a baseline input for three-dimensional (3D) and FE analyses. Three different models were compared for lateral MAT: intact, transpatellar approach, and parapatellar approach. Analysis was performed using high kinematic displacement and rotation inputs based on the kinematics of natural knees. ISO standards were used for axial load and flexion. Maximum contact stress on the grafted menisci and maximum shear stress on the articular surface of the knee joint were evaluated with FE analysis. RESULTS: Relatively high maximum contact stresses and maximum shear stresses were predicted in the medial meniscus and cartilage of the knee joint during the loading response for all three knee joint models. Maximum contact stress and maximum shear stress in the meniscus and cartilage increased on the lateral side after lateral MAT, especially during the first 20% of the stance phase of the gait cycle. The transpatellar approach was most similar to the intact knee model in terms of contact stresses of the lateral grafted and medial meniscus, as well as maximum shear stresses during the gait cycle. In addition, the transpatellar model had lower maximum contact stress on the menisci than did the parapatellar model, and it also had lower maximum shear stress on the tibial cartilage. CONCLUSIONS: Therefore, the transpatellar approach may reduce the overall risk of degenerative osteoarthritis (OA) after lateral MAT.

Acetylcholinesterase activity in the brain of wild birds in Korea-2014 to 2016.

Acetylcholinesterase (AChE) activity level can be used as a diagnostic marker for anticholinesterase pesticide poisoning. In this study, we aimed to establish a baseline level of normal brain AChE activity in wild birds. AChE activity was measured in the brains of 87dead wild birds (26 species). The level of AChE activity ranged from 6.40 to 15.9 µmol/min/g of brain tissue in normal wild birds. However, the brain tissue AChE activity level in wild birds exposed to organophosphate (OP) pesticide was 48.0%-96.3% of that in the normal birds. These results may serve as reference values to facilitate routine diagnosis and monitoring of OP-poisoned wild birds.

Guideline on safety evaluation of cell-based medicinal products for animal use.

With the increased use of cell therapy in the veterinary sector, there is a growing demand for the development of cell-based medicinal products and the determination of their safety. Currently, the Korean Animal and Plant Quarantine Agency has established a guideline for evaluating the safety of cell-based medicinal products for animal use. The guideline includes items related to definition, classification, management, manufacturing procedure and quality control (standard and test method), stability testing, toxicity testing, pharmacological testing, and performance of clinical trials. In addition, testing protocols related to safety assessment of animal cell-based products such as chromosome karyotyping, tumorigenicity testing, confirmatory testing of biodistribution and kinetics, and target animal safety testing are described in detail. Moreover, because cell-based medicinal products are novel therapies, deviations from traditional designs may be justified in order to obtain relevant safety information on the treatment. Additionally, this guideline can be amended on the basis of new scientific findings.

Pharmacokinetic and pharmacodynamic integration of enrofloxacin against Salmonella Enteritidis after administering to broiler chicken by per-oral and intravenous routes.

It is crucial to optimize the dose of fluoroquinolones to avoid antibiotic resistance and to attain clinical success. We undertook this study to optimize the dose of enrofloxacin against Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) in chicken by assessing its pharmacokinetic/pharmacodynamic (PK/PD) indices. The antibacterial activities of enrofloxacin against S. Enteritidis were evaluated. After administering 10 mg/kg body weight (b.w.) of enrofloxacin to broiler chickens of both sexes by intravenous (IV) and peroral (PO) routes, blood samples were drawn at different intervals and enrofloxacin concentrations in plasma were determined. PK/PD indices were calculated by integrating the PK and PD data. The elimination half-lives (T1/2), time required to reach peak concentration (Tmax), peak concentration (Cmax), and area under curve (AUC) after administering enrofloxacin by PO and IV routes were 25.84 ± 1.40 h, 0.65 ± 0.12 h, 3.82 ± 0.59 µg/mL, and 20.84 ± 5.0 µg·h/mL, and 12.84 ± 1.4 h, 0.22 ± 0.1 h, 6.74 ± 0.03 µg/mL, and 21.13 ± 0.9 µg.h/mL, respectively. The bioavailability of enrofloxacin was 98.6% ± 8.9% after PO administration. The MICs of enrofloxacin were 0.0625-1 µg/mL against S. Enteritidis strains, and the MIC50 was 0.50 µg/mL. The Cmax/MIC50 were 7.64 ± 0.2 and 13.48 ± 0.7 and the 24 h AUC/MIC50 were 41.68 ± 0.1 and 42.26 ± 0.3 after administering the drug through PO and IV routes, respectively. The data in this study indicate that the application of 50 mg/kg b.w. of enrofloxacin to chicken through PO and IV routes with a dosing interval of 24 h can effectively cure S. Enteritidis infection, indicating the need for a 5-fold increase in the recommended dosage of enrofloxacin in chicken.

High-content analysis of in vitro hepatocyte injury induced by various hepatotoxicants.

In vitro prediction of hepatotoxicity can enhance the performance of non-clinical animal testing for identifying chemical hazards. In this study, we assessed high-content analysis (HCA) using multi-parameter cell-based assays as an in vitro hepatotoxicity testing model using various hepatotoxicants and human hepatocytes such as HepG2 cells and human primary hepatocytes (hPHs). Both hepatocyte types were exposed separately to multiple doses of ten hepatotoxicants associated with liver injury whose mechanisms of action have been described. HCA data were obtained using fluorescence probes for nuclear size (Hoechst), mitochondrial membrane potential (TMRM), cytosolic free calcium (Fluo-4AM), and lipid peroxidation (BODIPY). Cellular alterations were observed in response to all hepatotoxicants tested. The most sensitive parameter was TMRM, with high sensitivity at a low dose, next was BODIPY, followed by Fluo-4AM. HCA data from HepG2 cells and hPHs were generally concordant, although some inconsistencies were noted. Both hepatocyte types showed mild or severe mitochondrial impairment and lipid peroxidation in response to several hepatotoxicants. The results demonstrate that the application of HCA to in vitro hepatotoxicity testing enables more efficient hazard identification, and further, they suggest that certain parameters could serve as sensitive endpoints for predicting the hepatotoxic potential of chemical compounds.