Identification Of Nucleic Acids Research Articles

Light-Driven Mitochondrion-to-Nucleus DNA Cascade Fluorescence Imaging and Enhanced Cancer Cell Photoablation.

Nucleic acids are mainly found in the mitochondria and nuclei of cells. Detecting nucleic acids in the mitochondrion and nucleus in cascade mode is crucial for understanding diverse biological processes. This study introduces a novel nucleic acid-based fluorescent styrene dye (SPP) that exhibits light-driven cascade migration from the mitochondrion to the nucleus. By introducing N-arylpyridine on one side of the styrene dye skeleton and a bis(2-ethylsulfanyl-ethy)-amino unit on the other side, we found that SPP exhibits excellent DNA specificity (16-fold, FDNA/Ffree) and a stronger binding force to nuclear DNA (-5.09 kcal/mol) than to mitochondrial DNA (-2.59 kcal/mol). SPP initially accumulates in the mitochondrion and then migrates to the nucleus within 10 s under light irradiation. By tracking the damage to nucleic acids in apoptotic cells, SPP allows the successful visualization of the differences between apoptosis and ferroptosis. Finally, a triphenylamine segment with photodynamic effects was incorporated into SPP to form a photosensitizer (MTPA-SPP), which targets the mitochondria for photosensitization and then migrates to the nucleus under light irradiation for enhanced photodynamic cancer cell treatment. This innovative nucleic acid-based fluorescent molecule with light-triggered mitochondrion-to-nucleus migration ability provides a feasible approach for the in situ identification of nucleic acids, monitoring of subcellular physiological events, and efficient photodynamic therapy.

New Breakthroughs in the Diagnosis of Leptomeningeal Carcinomatosis: A Review of Liquid Biopsies of Cerebrospinal Fluid.

Leptomeningeal carcinomatosis represents a terminal stage and is a devastating complication of cancer. Despite its high incidence, current diagnostic methods fail to accurately detect this condition in a timely manner. This failure to diagnose leads to the refusal of treatment and the absence of clinical trials, hampering the development of new therapy strategies. The use of liquid biopsy is revolutionizing the field of diagnostic oncology. The dynamic and non-invasive detection of tumor markers has enormous potential in cancer diagnostics and treatment. Leptomeningeal carcinomatosis is a conditionwhere invasive tissue biopsy is not part of the routine diagnostic analysis, making liquid biopsy an essential diagnostic tool. Several elements in cerebrospinal fluid (CSF) have been investigated as potential targets of liquid biopsy, including free circulating tumor cells, free circulating nucleic acids, proteins, exosomes, and even non-tumor cells as part of the dynamic tumor microenvironment. This review aims to summarize current breakthroughs in the research on liquid biopsy, including the latest breakthroughs in the identification of tumor cells and nucleic acids, and give an overview of future directions in the diagnosis of leptomeningeal carcinomatosis.

DNA Framework-Engineered Assembly of Cyanine Dyes for Structural Identification of Nucleic Acids.

DNA nanostructures serve as precise templates for organizing organic dyes, enabling the creation of programmable artificial photonic systems with efficient light-harvesting and energy transfer capabilities. However, regulating the organization of organic dyes on DNA frameworks remains a great challenge. In this study, we investigated the factors influencing the self-assembly behavior of cyanine dye K21 on DNA frameworks. We observed that K21 exhibited diverse assembly modes, including monomers, H-aggregates, J-aggregates, and excimers, when combined with DNA frameworks. By manipulating conditions such as the ion concentration, dye concentration, and structure of DNA frameworks, we successfully achieved precise control over the assembly modes of K21. Leveraging K21's microenvironment-sensitive fluorescence properties on DNA nanostructures, we successfully discriminated between the chirality and topology structures of physiologically relevant G-quadruplexes. This study provides valuable insights into the factors influencing the dynamic assembly behavior of organic dyes on DNA framework nanostructures, offering new perspectives for constructing functional supramolecular aggregates and identifying DNA secondary structures.

Convergence of Surface-Enhanced Raman Scattering with Molecular Diagnostics: A Perspective on Future Directions.

Molecular diagnostics (MD) is widely employed in multiple scientific disciplines, such as oncology, pathogen detection, forensic investigations, and the pharmaceutical industry. Techniques such as polymerase chain reaction (PCR) revolutionized the rapid and accurate identification of nucleic acids (DNA, RNA). More recently, CRISPR and its CRISPR-associated protein (Cas) have been a ground-breaking discovery that is the latest revolution in molecular biology, including MD. Surface-enhanced Raman scattering (SERS) is a very attractive alternative to fluorescence as the currently most widely used optical readout in MD. In this Perspective, milestones in the development of MD, SERS-PCR, and next-generation approaches to MD, such as Specific High-Sensitivity Enzymatic Reporter UnLOCKing (SHERLOCK) and DNA Endonuclease-Targeted CRISPR Trans Reporter (DETECTR), are briefly summarized. Our perspective on the future convergence of SERS with MD is focused on SERS-based CRISPR/Cas (SERS-CRISPR) since we anticipate many promising applications in this rapidly emerging field. We predict that major future developments will exploit the advantages of real-time monitoring with the superior brightness, photostability, and spectral multiplexing potential of SERS nanotags in an automated workflow for rapid assays under isothermal, amplification-free conditions.

P504 Prevalence of gastrointestinal infections in ulcerative colitis patients assessed with QIASTAT-DX® GASTROINTESTINAL PANEL 2

Abstract Background In inflammatory bowel disease (IBD), an acute clinical flare may be due to either disease exacerbation or an enteric infection. Thus, it is recommended to exclude infections before escalating IBD therapy. In this setting, conventional tests identify only a minimal proportion of infections (i.e. 10%). Whether nucleic acid multiplex tests can expand the range of detected pathogens and increase the overall prevalence is still a matter of debate. Methods We performed a single-center transversal prospective study at Fondazione IRCCS Policlinico Ca’ Granda. Stool samples from consecutive ulcerative colitis (UC) patients experiencing a disease flare and a group of patients in clinical remission were enrolled between February and October 2023 and tested with QIAstat-Dx Gastrointestinal Panel 2 (Qiagen GmbH, Hilden, Germany) for simultaneous qualitative detection and identification of nucleic acids from multiple viruses, bacteria, and parasites. Clinically active disease was defined as a Partial Mayo Score (PMS) of ≥2. Results Overall, 85 UC patients were enrolled. Demographics and clinical features are displayed in Table 1. Median age was 42 (18-79), 52% were males. The two most common treatment regimens were mesalamine (54%) and biologic/small molecule treatment (35%). 66 (78%) patients were clinically active, while 19 (22%) were in remission. In the active group, median bowel movements were 5 (3-15), 58 (88%) patients had loose stool, 32 (49%) reported abdominal pain, 40 (61%) urgency, 10 (15%) overnight symptoms, 6 (9%) fever. Median PMS was 5 (2-8). Median hemoglobin was 13.8 (8.2-16.4) g/dL, fecal calprotectin 508 (<5-4980) ug/g. Prevalence of gastrointestinal infections with QIAstat-Dx was 30 vs. 10% (p=0.13) in active vs. remission group, respectively. The most common infections were: C.Difficile infection (CDI) (4 cases), Cytomegalovirus (CMV) (4 cases) and enteropathogenic E.Coli (EPEC) (4 cases). Regarding viral and E. Coli infections, clinical remission (PMS <2) occurred spontaneously. As for CMV, Campylobacter spp., and CDI, all patients except one achieved remission following specific antimicrobial treatment. In one patient CMV infection led to hospital admission (circulating CMV DNA 35,395 IU/mL). The remaining patient did not receive specific antiviral therapy since sigmoidoscopy only detected isolated CMV+ cells, and remission was achieved with UC treatment escalation. Conclusion In UC patients experiencing a clinical flare, prevalence of gastrointestinal infections with QIAstat-Dx® Gastrointestinal Panel 2 is numerically higher than patients in remission. Further studies are needed to investigate whether increased detection could influence the clinical outcomes of IBD patients and time and costs for the healthcare system.

Nanozyme-assisted amplification-free CRISPR/Cas system realizes visual detection.

The CRISPR (clustered regularly interspaced short palindromic repeats)/Cas (CRISPR associated) system has proven to be a powerful tool for nucleic acid detection due to its inherent advantages of effective nucleic acid identification and editing capabilities, and is therefore known as the next-generation of molecular diagnostic technology. However, the detection technologies based on CRISPR/Cas systems require preamplification of target analytes; that is, target gene amplification steps through isothermal amplification or PCR before detection to increase target analyte concentrations. This creates a number of testing limitations, such as extended testing time and the need for more sophisticated testing instruments. To overcome the above limitations, various amplification-free assay strategies based on CRISPR/Cas systems have been explored as alternatives, which omit the preamplification step to increase the concentrations of the target analytes. Nanozymes play a pivotal role in enhancing the sensitivity of CRISPR-based detection, enabling visual and rapid CRISPR assays. The utilization of nanozyme exceptional enzyme-like catalytic activity holds great promise for signal amplification in both electrochemical and optical domains, encompassing strategies for electrochemical signal sensors and colorimetric signal sensors. Rather than relying on converting a single detection target analyte into multiple analytes, these methods focus on signal amplification, the main mechanism of which involves the ability to form a large number of reporter molecules or to improve the performance of the sensor. This exploitation of nanozymes for signal amplification results in the heightened sensitivity and accuracy of detection outcomes. In addition to the strategies that improve sensor performance through the application of nanozymes, additional methods are needed to achieve visual signal amplification strategies without preamplification processes. Herein, we review the strategies for improving CRISPR/Cas systems that do not require preamplification, providing a simple, intuitive and preamplification-free CRISPR/Cas system detection platform by improving in-system one-step amplification programs, or enhancing nanozyme-mediated signal amplification strategies.

Dengue Fever: Etiology, Diagnosis, Prevention and Treatment

Dengue fever (break-bone fever) is a viral disease transmitted by Aedes mosquitoes. It is caused by the Dengue virus, which is a single positive-stranded RNA virus belonging to the Flaviviridae family. Dengue fever is prevalent in tropical and subtropical areas and is a significant public health concern in many countries, including`g Nigeria. The disease is characterized by symptoms such as high fever, headache, body aches, nausea, vomiting, swollen glands, and rash. In severe cases, dengue fever can lead to complications such as bleeding, organ impairment, and dengue shock syndrome. Diagnosing dengue fever can be challenging, especially in areas where it is endemic. In endemic locations, diagnosis is often made clinically based on the patient's reported symptoms and a physical examination. Tourniquet testing, which involves applying a blood pressure cuff and counting any petechial hemorrhages, can help in the diagnosis. Laboratory methods, including full blood count, cell culture, nucleic acid identification (PCR), and serology, can be used to confirm the diagnosis. Preventing dengue fever involves controlling the mosquito vector and protecting oneself from mosquito bites. Measures such as eliminating mosquito breeding sites, using insect repellents, wearing protective clothing, and using bed nets can help prevent mosquito bites. Vaccination against dengue is also available, with the Dengvaxia vaccine being used in some countries. There is no specific antiviral treatment for dengue fever. Management focuses on supportive care, maintaining a healthy fluid balance, and relieving symptoms such as fever and pain. Severe cases may require hospitalization and intensive medical care. In Nigeria, dengue fever is often misdiagnosed or overlooked due to similarities with other febrile illnesses like malaria. This can lead to underreporting and inadequate management of dengue cases. Increasing awareness among healthcare professionals and the general population is crucial for early detection and appropriate management of dengue fever in Nigeria. In conclusion dengue fever is a viral disease transmitted by mosquitoes, primarily Aedes species. It is a significant global health concern, including in Nigeria. Early diagnosis, prevention measures, and supportive care are essential in managing dengue fever and reducing its impact on public health. This review is aimed at discussing the current issues of Dengue fever with focus on Nigeria.

QUALITY OF LIFE INDICATORS FOR THE PATIENTS WHO SUFFERED FROM COMMUNITY-ACQUIRED PNEUMONIA CAUSED BY SARS-CoV-2

Introduction. Respiratory pathology, both acute and chronic, remains one of the key problems of modern medicine in Ukraine and in the world in general, which is explained by its significant prevalence, negative impact on patients' work capacity, their quality of life, as well as the economic burden on society. The aim of the study – to analyze the subjective state of health using the SF-36 questionnaire for patients who undergone community-acquired pneumonia caused by SARS-CoV-2 in 1 year after inpatient treatment. Research Methods. A retrospective study of the medical records of 208 patients who had been hospitalized for non-hospital pneumonia with a negative smear test for the SARS-CoV-2 virus was conducted. The severity of pneumonia was calculated according to the PORT scale. The comparison group consisted of patients with SARS-CoV-2 nucleic acid identification and the absence. A telephone survey to assess the quality of life of the participants of the first stage of our study 1 year after discharge from the hospital were performed. The general investigator SF-36 was used to assess quality of life. Statistical analysis of data was carried out using the "STATISTICA 7.0" software. Results and Discussion. Physical functioning according to SF-36 was the lowest in the observation group IV and probably differed in relation to the data of the observation group II and the comparison group. Analyzing the general state of health, the values were found to be probably lower for patients who suffered from community-acquired pneumonia of 3rd and 4th categories of severity compared to the data of the observation group II and the comparison group. Conclusion. Thus, it was established low quality of life in patients after pneumonia caused by COVID-19. Practical value of the work consists in improving diagnostics and therapy, as well as improving the rehabilitation of patients who suffered from community-acquired pneumonia caused by SARS-CoV-2.

Markers of quality of life in patients with nosocomial pneumonia caused by SARS-CoV-2

Objective — to investigate and analyze total white blood cell count and leukogram in an order with community-acquired pneumonia caused by SARS-CoV-2 and to establish their relationship with subjective health assessment using the SF-36 tool 1 year after hospital discharge.
 Materials and methods. A retrospective study of the medical records of 208 patients who were hospitalized for community-acquired pneumonia with a negative smear test for the SARS-CoV-2 virus was conducted. The main group consisted of patients with SARS-CoV-2 nucleic acid identification and signs of pneumonia. According to the severity of pneumonia, patients were divided into three groups: II group —patients with pneumonia of category 2 of complexity (n = 124), group III — patients with pneumonia of category 3 of complexity (n = 68), group IV — patients with pneumonia of category 4 of complexity (n = 16). The comparison group consisted of patients with SARS-CoV-2 nucleic acid identification and the absence of pneumonia. Charlson’s comorbidity index (Charlson Comorbidity Index) for the general prognosis of mortality was calculated using a special computer program. The general questionnaire SF-36 was used to assess the quality of life. Statistical analysis of data was carried out using the Statistica 7.0 software.
 Results and discussion. Probably higher values ​​of the total number of leukocytes were established in the patients of the studied groups compared to the comparison group. At the same time, this indicator in patients of the IV group statistically significantly exceeded the similar data of the II and III groups. The increase in leukocytes as the complexity of pneumonia progressed was mainly due to segmented neutro­phils. In patients with acquired pneumonia of the 3rd and 4th severity category caused by SARS-CoV-2 1 year after discharge from the hospital, the indicators of physical and psychological components of health are likely to be lower, while increasing age is likely to be associated with a decrease in quality of life.
 Conclusions. In patients with community-acquired pneumonia caused by COVID-19, an increase in the content of leukocytes upon admission to the hospital is associated with a decrease in indicators of physical and psychological components of health 1 year after discharge from the hospital.

CRISPR based biosensing: An ultrasensitive theranostic tool for the detection of early Breast Cancer biomarkers – A mini review

According to The International Agency for Research on Cancer (IARC) survey, the most commonly diagnosed breast cancer (BC) encumbrance will rise to ˃3 million with ˃1 million bereavements per year by 2040. This creates a high demand for effective early diagnosis of BC to reduce psychological and economic distress. Recently, the body fluid cancer biomarkers detection, a minimally invasive method has an imperative role to identify the cancer stages for developing new strategies for early diagnosis. Traditional complicated and sophisticated detection tool preparation and time consuming detection technologies are lately replaced with nanotechnology incorporated Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated protein (CRISPR/Cas) technology based biosensors. This technology is an in vitro, next generation ultrasensitive diagnostic device meant to achieve highly specific, ultra-sensitive, and rapid identification of BC nucleic acids, protein biomarkers, whole cells, and small molecules. Till date, many reviews focussing on the use of this technology in diagnosing contagious diseases, liver and colon cancers and later state BC biomarkers are published. Yet review article highlighting the CRISPR/Cas modified biosensors and point-of-care devices (POCDs), exclusively for early BC detection is rarely reported. Hence, this review involves critical thinking on CRISPS-Cas based biosensors research published between Jan 2017–Nov 2022 especially for early BC biomarkers based liquid biopsy diagnosis to develop ultrasensitive and rapid POC tool. The challenges faced by the researchers to bring out CRISPR based biosensing into real time and the future perspectives are also briefed at the end.

Nucleic Acid Analytical Techniques - Current era of Development Perspectives in Diagnosis Field

Nucleic acid identification, separation, purification, sequencing, diagnosis mapping, etc. are emerging field of bioscience. While designing acceptable method is crucial part of analyser. The repetitive task assigned during method the development and controlling the internal as well as external parameters may design a prominent approach for identification. The interpretation is also directed towards functional complexity of genetic disorders. The high-resolution techniques are minimize the biological barriers in recent developments and focusing on independent structure. The nucleic acid analysis is increasing in the field of bioscience and most preferable application in diagnostic laboratories at commercial scale. Identification of nucleic acid sequence will going to be applied in the analytical aspects like forensic samples, medicines, diseases identification, staging and few more environmental applications. The paper highlights the recent developments of laboratory methods in nucleic acid analysis and their commercial paradigm is necessary in current era of developmental perspectives in diagnosis field.

Evidence of a novel cross-species transmission by ovine papillomaviruses.

Ovine papillomavirus (OaPV) comprises four genotypes; OaPV1, OaPV2 and OaPV4 are fibropapillomaviruses within the genus Deltapapillomavirus, whereas OaPV3 is an epitheliotropic virus that belongs to the genus Dyokappapapillomavirus. To date, all of them have been known to infect sheep only. OaPV1, OaPV2 and OaPV4 have been associated with ovine cutaneous and mucosal fibropapillomas, whereas OaPV3 is a key factor in the squamous cell carcinoma pathway of the sheep skin. Whole blood samples obtained from 128 cattle at public slaughterhouses were investigated using droplet digital polymerase chain reaction (ddPCR). ddPCR is a new-generation PCR technique that enables an accurate and absolute quantification of target molecules with high sensitivity and specificity. All OaPVs were detected by identification and quantification of nucleic acids using specific fluorescent probes. Of 128 blood samples, 100 (∼78%) showed OaPV infections. Further, 42, 35 and 23 blood samples showed single, double and triple OaPV infections, respectively. OaPV1 was responsible for 22 single infections, OaPV2 caused 16 single infections and OaPV3 and OaPV4 caused two single infections each. OaPV1 and OaPV2 were the most frequent ovine viruses in dual and triple infections. In many blood samples, both ovine deltapapillomavirus and dyokappapapillomaviruswere found to be transcriptionally active, as shown by the detection and quantification of E5 oncogene transcripts for OaPV1, L1 transcripts for OaPV2, E6 and E7 transcripts for OaPV3 and E6 for OaPV4. OaPVs were found in the blood samples from cattle that shared grasslands rich in bracken ferns known to contain immunosuppressant substances. Furthermore, OaPVs were also found in cattle from intensive livestock farming without any contact with sheep. Because OaPV DNA was detected in both grass hay and corn silage, it is conceivable that these feed may be the viral sources.

Principles and Applications of Loop-Mediated Isothermal Amplification to Point-of-Care Tests.

For the identification of nucleic acids, which are important biomarkers of pathogen-mediated diseases and viruses, the gold standard for NA-based diagnostic applications is polymerase chain reaction (PCR). However, the requirements of PCR limit its application as a rapid point-of-care diagnostic technique. To address the challenges associated with regular PCR, many isothermal amplification methods have been developed to accurately detect NAs. Isothermal amplification methods enable NA amplification without changes in temperature with simple devices, as well as faster amplification times compared with regular PCR. Of the isothermal amplifications, loop-mediated isothermal amplification (LAMP) is the most studied because it amplifies NAs rapidly and specifically. This review describes the principles of LAMP, the methods used to monitor the process of LAMP, and examples of biosensors that detect the amplicons of LAMP. In addition, current trends in the application of LAMP to smartphones and self-diagnosis systems for point-of-care tests are also discussed.

An ELISA-based platform for rapid identification of structure-dependent nucleic acid–protein interactions detects novel DNA triplex interactors

Unusual nucleic acid structures play vital roles as intermediates in many cellular processes and, in the case of peptide nucleic acid (PNA)–mediated triplexes, are leveraged as tools for therapeutic gene editing. However, due to their transient nature, an understanding of the factors that interact with and process dynamic nucleic acid structures remains limited. Here, we developed snapELISA (structure-specific nucleic acid-binding protein ELISA), a rapid high-throughput platform to interrogate and compare up to 2688 parallel nucleic acid structure–protein interactions in vitro. We applied this system to both triplex-forming oligonucleotide–induced DNA triplexes and DNA-bound PNA heterotriplexes to describe the identification of previously known and novel interactors for both structures. For PNA heterotriplex recognition analyses, snapELISA identified factors implicated in nucleotide excision repair (XPA, XPC), single-strand annealing repair (RAD52), and recombination intermediate structure binding (TOP3A, BLM, MUS81). We went on to validate selected factor localization to genome-targeted PNA structures within clinically relevant loci in human cells. Surprisingly, these results demonstrated XRCC5 localization to PNA triplex-forming sites in the genome, suggesting the presence of a double-strand break intermediate. These results describe a powerful comparative approach for identifying structure-specific nucleic acid interactions and expand our understanding of the mechanisms of triplex structure recognition and repair.

Ultra-Sensitive and Rapid Detection of Pathogenic Yersinia enterocolitica Based on the CRISPR/Cas12a Nucleic Acid Identification Platform.

Yersinia enterocolitica is a dangerous foodborne human pathogen that mainly causes gastroenteritis. Ideal methods for the detection of pathogens in food should be rapid, sensitive, specific, and cost effective. To this end, novel in vitro nucleic acid identification methods based on clustered, regularly interspaced short palindromic repeats (CRISPR)-associated protein (Cas) endonuclease have received increasing attention. In this study, a simple, visual, and ultrasensitive method, based on CRISPR/Cas12a with recombinase polymerase amplification (RPA), was developed for the detection of Y. enterocolitica. The results show that a specific attachment invasion locus gene (ail) can be rapidly detected using a CRISPR/Cas12a-RPA-based system. Application of the method to raw pork, which was artificially infected with Y. enterocolitica, achieved an estimated detection limit of 1.7 CFU/mL in less than 45 min, and this was 100 times lower compared with qPCR. The results indicated that the CRISPR/Cas12a-RPA system has good potential for monitoring pathogenic Y. enterocolitica in the chilled meat supply chain.

Advances in Nucleic Acid Amplification-Based Microfluidic Devices for Clinical Microbial Detection

Accurate and timely detection of infectious pathogens is urgently needed for disease treatment and control of possible outbreaks worldwide. Conventional methods for pathogen detection are usually time-consuming and labor-intensive. Novel strategies for the identification of pathogenic nucleic acids are necessary for practical application. The advent of microfluidic technology and microfluidic devices has offered advanced and miniaturized tools to rapidly screen microorganisms, improving many drawbacks of conventional nucleic acid amplification-based methods. In this review, we summarize advances in the microfluidic approach to detect pathogens based on nucleic acid amplification. We survey microfluidic platforms performing two major types of nucleic acid amplification strategies, namely, polymerase chain reaction (PCR) and isothermal nucleic acid amplification. We also provide an overview of nucleic acid amplification-based platforms including studies and commercialized products for SARS-CoV-2 detection. Technologically, we focus on the design of the microfluidic devices, the selected methods for sample preparation, nucleic acid amplification techniques, and endpoint analysis. We also compare features such as analysis time, sensitivity, and specificity of different platforms. The first section of the review discusses methods used in microfluidic devices for upstream clinical sample preparation. The second section covers the design, operation, and applications of PCR-based microfluidic devices. The third section reviews two common types of isothermal nucleic acid amplification methods (loop-mediated isothermal amplification and recombinase polymerase amplification) performed in microfluidic systems. The fourth section introduces microfluidic applications for nucleic acid amplification-based detection of SARS-CoV-2. Finally, the review concludes with the importance of full integration and quantitative analysis for clinical microbial identification.

SARS-CoV-2 Breath Tests Implementation for the Rapid COVID-19 Surveillance: A Game Changer?- A Review of Existing Data

The Coronavirus Disease 2019 (COVID-19) pandemic has been spread across the globe for almost a year, causing economic, social, and psychological impacts with yet unknown dimensions. In emerging and reemerging pathogen surveillance and detection, polymerase chain reaction (PCR) is a classic laboratory technique that has been widely used for the amplification and identification of nucleic acids. Analysis of volatile organic compounds (VOCs) in breath has been long reviewed as a potential diagnostics tool for many diseases. The overall specificity for SARS-CoV-2 of these methods was a calculated 69%,30 which is a low value for reliable detection. Breath tests are not a sufficiently evidence-based approach for rapid screening and to "secure" or creating "sanctuary" regions for touristic purposes. Therefore, policy-makers must cautiously point out the importance of further evaluation and structured studies confronting gold-standards with new devices.

COVID-19 ‘asymptomatic’ patients: an old wives’ tale

ABSTRACT Introduction A novel virus, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was reported via nucleic acid identification in December, 2019. ‘Asymptomatic cases’ have arised as an obstacle for an accurate diagnosis, curtailing the elimination of the ongoing pandemic. Areas covered In this review, we analyze the definition of symptoms and the principles of diagnosing COVID-19. Also, we explore the major reasons for cases presenting a phenotype with mild symptoms. Host, viral and environmental aspects for a COVID-19 leading to mild symptoms are being highlighted. A final aspect regarding a rational asymptomatic COVID-19 is presumed. Expert opinion Diagnosing a pandemic via a sole test can be risky. Epidemiological administration should be more accurate and precise, not only for the societal pandemic levels and following policies, but for the same scientific community, that studies SARS-CoV-2 and its mutants. Several other issues should be answered before analyzing human genome for the asymptomatic scenario.

Conductance and tunnelling current characteristics for individual identification of synthetic nucleic acids with a graphene device.

Based on combined density functional theory and non-equilibrium Green's function quantum transport studies, in the present work we have demonstrated the quantum interference (QI) effect on the transverse conductance of Hachimoji (synthetic) nucleic acids when placed between the oxygen-terminated zigzag graphene nanoribbon (O-ZGNR) nanoelectrodes. We theorize that the QI effect could be well preserved in π-π coupling between a target nucleobase molecule and the carbon-based nanoelectrodes. Our study indicates that the QI effect, such as anti-resonance or Fano-resonance, affects the variation of transverse conductance depending on the nucleobase conformation. Furthermore, a variation of up to 2-5 orders of magnitude is observed in the conductance upon rotation for all the nucleobases. The current-voltage (I-V) characteristics results suggest a distinct variation in the electronic tunnelling current across the proposed nanogap device for all five nucleobases with the applied bias voltage ranges from 0.1-1.0 V. The different rotation angles keep the distinct feature of the nucleobases in both transverse conductance and tunnelling current features. Both features could be utilized in an accurate synthetic DNA sequencing device.

An RNA-cleaving threose nucleic acid enzyme capable of single point mutation discrimination.

Threose nucleic acid has been considered a potential evolutionary progenitor of RNA because of its chemical simplicity, base pairing properties and capacity for higher-order functions such as folding and specific ligand binding. Here we report the in vitro selection of RNA-cleaving threose nucleic acid enzymes. One such enzyme, Tz1, catalyses a site-specific RNA-cleavage reaction with an observed pseudo first-order rate constant (kobs) of 0.016 min-1. The catalytic activity of Tz1 is maximal at 8 mM Mg2+ and remains relatively constant from pH 5.3 to 9.0. Tz1 preferentially cleaves a mutant epidermal growth factor receptor RNA substrate with a single point substitution, while leaving the wild-type intact. We demonstrate that Tz1 mediates selective gene silencing of the mutant epidermal growth factor receptor in eukaryotic cells. The identification of catalytic threose nucleic acids provides further experimental support for threose nucleic acid as an ancestral genetic and functional material. The demonstration of Tz1 mediating selective knockdown of intracellular RNA suggests that functional threose nucleic acids could be developed for future biomedical applications.