Narrowing Signal Distribution by Adamantane Derivatization for Amino Acid Identification Using an α-Hemolysin Nanopore.

The rapid progress in nanopore sensing has sparked interest in protein sequencing. Despite recent notable advancements in amino acid recognition using nanopores, chemical modifications usually employed in this process still need further refinements. One of the challenges is to enhance the chemical specificity to avoid downstream misidentification of amino acids. By employing adamantane to label proteinogenic amino acids, we developed an approach to fingerprint individual amino acids using the wild-type α-hemolysin nanopore. The unique structure of adamantane-labeled amino acids (ALAAs) improved the spatial resolution, resulting in distinctive current signals. Various nanopore parameters were explored using a machine-learning algorithm and achieved a validation accuracy of 81.3% for distinguishing nine selected amino acids. Our results not only advance the effort in single-molecule protein characterization using nanopores but also offer a potential platform for studying intrinsic and variant structures of individual molecules.

Evaluation of Online Andrology Medical Services in Central Regions of China During the COVID-19 Pandemic: A Cross-Sectional Data Analysis Study.

To provide an overview of the current situation, challenges, and trends in online medical services from the perspective of andrology and promote the development of online medical services. Users of the Learning Alliance of Urology, who mainly worked in central regions of China, were invited to complete the questionnaire that included information on the participants and their institutions and their involvement in and concerns for online medical services. We received 875 complete responses. The percentage of online andrology patients at most institutions was less than 30%. The most common services were online appointment registration (92.7%) and online payment (81.8%). Online chat consultation (77.7%) was the most common form of consultation. Only 1 in 5 of the institutions had constructed their Internet hospital. Factors related to the percentage of online andrology patients included specialized andrology clinics and wards, sufficient time for doctors to provide online services, more diversified services, and online clinic training. The biggest challenge for online medical services was diagnosis and treatment safety. It is essential to raise awareness of online medical services for hospitals and patients and strengthen standardized management and training of online medical services, especially applicable to central regions of China. However, online medical services cannot wholly replace offline services due to insufficient diagnosis and treatment.

Influences of temperature and salinity on holistic network performability of multi-AUV cooperative systems.

This study proposes holistic network performability as a reliability index of multiple autonomous underwater vehicle (AUV) (multi-AUV) cooperative systems and deduces the reliability of communication links. Temperature and salinity vary in different areas of the sea. The influence mechanism of temperature and salinity on holistic network performability is discussed. An example is provided to show the influences of temperature and salinity on holistic network performability. Corresponding trends of holistic network performability with the influences of temperature and salinity can be obtained. The trends show that the holistic network performability of multi-AUV cooperative systems exhibit ladder-like increases with temperature and salinity. In each ladder, the value of holistic network performability changes rapidly at high salinity or low temperature. The study on the change of the reliability of multi-AUV cooperative systems under different temperatures and salinities provides a theoretical basis for the reliability research of multi-AUV cooperative systems and provides reference for future practical application of multi-AUV cooperative systems and other network systems.

Structure-activity relationship analysis of curcumin analogues on anti-influenza virus activity.

Curcumin (Cur) is a commonly used colouring agent and spice in food. Previously, we reported that Cur inhibits type A influenza virus (IAV) infection by interfering with viral haemagglutination (HA) activity. To search for a stable Cur analogue with potent anti-IAV activity and to investigate the structure contributing to its anti-IAV activity, a comparative analysis of structural and functional analogues of Cur, such as tetrahydrocurcumin (THC) and petasiphenol (Pet), was performed. The result of time-of-drug addition tests indicated that these curcuminoids were able to inhibit IAV production in cell cultures. Noticeably, Pet and THC inhibit IAV to a lesser extent than Cur, which is in line with their effect on reducing plaque formation when IAV was treated with Cur analogues before infection. Unexpectedly, both THC and Pet did not harbour any HA inhibitory effect. It should be noted that the structure of Pet and THC differs from Cur with respect to the number of double bonds present in the central seven-carbon chain, and structure modelling of Cur analogues indicates that the conformations of THC and Pet are distinct from that of Cur. Moreover, simulation docking of Cur with the HA structure revealed that Cur binds to the region constituting sialic acid anchoring residues, supporting the results obtained by the inhibition of HA activity assay. Collectively, structure-activity relationship analyses indicate that the presence of the double bonds in the central seven-carbon chain enhanced the Cur -dependent anti-IAV activity and also that Cur might interfere with IAV entry by its interaction with the receptor binding region of viral HA protein.

Inhibition of enveloped viruses infectivity by curcumin.

Curcumin, a natural compound and ingredient in curry, has antiinflammatory, antioxidant, and anticarcinogenic properties. Previously, we reported that curcumin abrogated influenza virus infectivity by inhibiting hemagglutination (HA) activity. This study demonstrates a novel mechanism by which curcumin inhibits the infectivity of enveloped viruses. In all analyzed enveloped viruses, including the influenza virus, curcumin inhibited plaque formation. In contrast, the nonenveloped enterovirus 71 remained unaffected by curcumin treatment. We evaluated the effects of curcumin on the membrane structure using fluorescent dye (sulforhodamine B; SRB)-containing liposomes that mimic the viral envelope. Curcumin treatment induced the leakage of SRB from these liposomes and the addition of the influenza virus reduced the leakage, indicating that curcumin disrupts the integrity of the membranes of viral envelopes and of liposomes. When testing liposomes of various diameters, we detected higher levels of SRB leakage from the smaller-sized liposomes than from the larger liposomes. Interestingly, the curcumin concentration required to reduce plaque formation was lower for the influenza virus (approximately 100 nm in diameter) than for the pseudorabies virus (approximately 180 nm) and the vaccinia virus (roughly 335 × 200 × 200 nm). These data provide insights on the molecular antiviral mechanisms of curcumin and its potential use as an antiviral agent for enveloped viruses.