Aptamer-graphene oxide for highly sensitive dual electrochemical detection of Plasmodium lactate dehydrogenase

A 90 mer ssDNA aptamer (P38) enriched against Plasmodium falciparum lactate dehydrogenase (PfLDH) through SELEX process was immobilized over glassy carbon electrode (GCE) using graphene oxide (GO) as an immobilization matrix, and the modified electrode was investigated for detection of PfLDH. The GO was synthesized from powdered pencil graphite and characterized by XRD based on the increased interlayer distance between graphitic layers from 0.345 nm for graphite to 0.829 nm for GO. The immobilization of P38 on GO was confirmed by I_D/I_G intensity ratio in Raman spectra where, the ratio were 0.67, 0.915, and 1.35 for graphite, GO and P38-GO, respectively. The formation of the P38 layer over GO-GCE was evident from an increase in the surface height in AFM analysis of the electrode from ∼3.5 nm for GO-GCE to ∼27 nm for P38-GO-GCE. The developed aptasensor when challenged with the target, a detection of as low as 0.5 fM of PfLDH was demonstrated. The specificity of the aptasensor was confirmed through a voltametric measurement at 0.65 V of the reduced co-factor generated from the PfLDH catalysis. Studies on interference from some common proteins, storage stability, repeatability and analysis of real samples demonstrated the practical application potential of the aptasensor.     

Materials Effect in Sensing Performance Based on Surface Plasmon Resonance Using Photonic Crystal Fiber

Plasmonics - This article explores the effect of sensing performances with subject to change in different types of material and this study is carried out by the support of plasmon-coated photonic...     

Long-term cultured human skin mast cells are suitable for pharmacological studies of anti-allergic drugs due to high responsiveness to FcεRI cross-linking

Human skin mast cells proliferated in the presence of interleukin (IL)-4+SCF (expanding 18-fold in 8 weeks) and acquired profound responsiveness towards high affinity IgE receptor (FcεRI) cross-linking, liberating about 75% of their histamine. In a proof-of-concept, we found that these cells are useful for pharmacological testing. Even a subtle inhibition of degranulation can be visualized. This model might prove valuable in tests of novel anti-allergic drugs.     

Effect of nucleotides on the oligomeric state of human lactoferrin

Lactoferrin (LF) is a multifunctional acute-phase protein involved in nonspecific defense against bacteria, viruses, and cancer diseases and is present in human barrier fluids, blood, and milk. Small-angle X-ray scattering (SAXS) and light scattering (LS) demonstrated for the first time that LF occurs in the form of oligomers, with a high monomer unit number in the solution. The degree of LF oligomerization depends on the LF concentration and the storage period of non-frozen neutral LF solutions. The average inertial radius of scattering particles (R _g) reaches 100–450 Å at LF concentrations comparable with those in human milk, while R _g of LF monomers is 26.7 Å. LF forms complexes with various nucleotides and hydrolyzes them. The addition of ATP or AMP to LF solutions accelerates LF oligomerization and increases R _g to 600–700 Å, regardless of the initial degree of LF oligomerization. According to the different models (sphere, plate, and cylinder) of LF aggregates, its complexes with such R _g presumably contain several tens to thousands of LF monomers. The possible role of oligomeric complexes in multiple biological functions of LF is discussed.     

Characterization of heterotrimeric nucleotide-depleted Gα(i)-proteins by Bodipy-FL-GTPγS fluorescence anisotropy

Recombinant heterotrimeric G-protein α_i1, α_i2 and α_i3 subunits were purified in GDP-depleting conditions by affinity chromatography using StrepII-tagged β₁γ₂ subunits. Real-time monitoring of fluorescence anisotropy of Bodipy-FL-GTPγS was used for characterization of nucleotide binding properties and inactivation of the purified proteins. All GDP-depleted α_i were unstable at room temperature and therefore nucleotide binding could be characterized only in a nonequilibrium state. In comparison to Mg²⁺, Mn²⁺ inhibited nucleotide binding to all α_i-heterotrimers studied and accelerated nucleotide release. Mn²⁺ had stabilizing effect on the nucleotide free state of the α_i1 subunit, whereas both Mn²⁺ as well as G-protein activation by mastoparan destabilized the α_i2 subunit.     

Rabies epidemiology,prevention and control in Nigeria: Scoping progress towards elimination

BackgroundHuman rabies remains a significant public health problem in Africa with outbreaks reported in most countries. In Nigeria–the most populous country in Africa–rabies causes a significant public health burden partly due to perennial obstacles to implementing a national prevention and control program.MethodsWe conducted a scoping review using standard Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify and select published articles from Nigeria during 1978–2020 reporting on rabies virus infections (human, canine, livestock, and wildlife), canine bites, knowledge, attitudes and practices (KAP) surveys on rabies and canine ecology studies. We extracted information on study location, year and additional details of each study such as rabies prevalence, general characteristics of offending dogs, dog vaccination status and health-seeking behaviours.FindingsBetween 1978 and 2020, 90 published articles met our inclusion criteria. The prevalence of rabies virus antigen detection varied between 3% and 28%, with more studies in the north. Most bites were unprovoked from dog bite studies (36.4%-97%), by dogs with low vaccination rates (12–38%). A more significant proportion of biting dogs were owned (31–90%). Laboratory confirmation for biting was available for only a small proportion of studies (6%; n = 2/32). Of the dogs surveyed during ecology studies, indigenous dogs accounted for the majority (62–98%), used mostly for security purposes (52–98%), with the vaccination rate between 15% and 38% in most states. Studies conducted in areas distant from rabies diagnostic facilities accounted for more human rabies cases and fewer dog rabies cases.ConclusionSignificant improvements are necessary to achieve the elimination of human rabies mediated via dogs by 2030.     

ICAM-3 (CD50) is expressed by human mast cells: induction of homotypic mast cell aggregation via ICAM-3

Intercellular adhesion molecule-3 (ICAM-3, CD50), an adhesion receptor of the immunoglobulin superfamily, is suggested to play a key role in adhesive cellular interactions during the initial phase of an immune response. We here provide evidence that ICAM-3 is abundantly expressed by cells of the human mast cell line HMC-1 and, to a lower degree, by purified skin mast cells, as demonstrated by flow-cytometry, ELISA and RT-PCR. ICAM-3 immunoprecipitated from surface biotinylated HMC-1 cells migrates as a broad band of Mr 124,000 by Western blot analysis. We also demonstrate that monoclonal antibodies directed against ICAM-3 are capable of inducing rapid HMC-1 cell aggregation, the extent of which strongly depends on the epitope recognized by the mAb applied. Interestingly, although inhibitable by two of six mAbs against LFA-1, HMC-1 aggregation induced via ICAM-3 appears to be mediated by an adhesive pathway independent of LFA-1. Dermal mast cells are also aggregated with anti-ICAM-3 mAbs, a phenomenon which has not been described before for isolated tissue mast cells. However, this process displays slower kinetics, as compared to HMC-1 cells. That anti-ICAM-3 mAbs are able to mediate biological effects is further illustrated by their capability to increase stimulation-dependent release of the pro-inflammatory cytokines interleukin-6 (IL-6) and IL-8 from HMC-1 cells. Taken together, these results indicate that ICAM-3 is not only expressed by immature and mature human mast cells, but also possesses functional relevance and may therefore play a significant role in mast cell associated processes.     

Lactoferrin interacts with nucleotides

Lactoferrin (LF) is an iron-binding glycoprotein found predominantly in milk and in granulocytes. LF is extremely polyfunctional protein some biological functions of which are determined by its capacity to bind iron, but many other functions are iron-independent. In this article we show for the first time that LF interacts with a number of various mononucleotides.