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In this work, we proposed a convenient fluorescent assay for the detection of quinolones based on their inhibition towards the oxidation of o-phenylenediamine (OPD) by copper ions (Cu2+). Free Cu2+ can oxidize OPD into fluorescent 2,3-diaminophenzine followed by the formation of copper nanoparticles (CuNPs), which would further catalyze the oxidation of OPD. When quinolones were added, their strong binding affinity to Cu2+ inhibited the oxidase-like activity of Cu2+. So, the fluorescence intensity of the Cu2+–OPD system decreased obviously. The determination of quinolones can be achieved by using this fluorimetric assay without the use of complicated instruments and protocols. As demonstrated, this assay offered a highly sensitive readout for quinolones including nalidixic acid, cinoxacin, ciprofloxacin, and moxifloxacin in the linear ranges of 1.0–100 nM, 0.5–100 nM, 1.0–100 nM, and 0.1–100 nM, respectively. In addition, the developed assay was successfully applied to the direct analysis of quinolones in real amples. [ABSTRACT FROM AUTHOR]

In this work, we proposed a convenient fluorescent assay for the detection of quinolones based on their inhibition towards the oxidation of o-phenylenediamine (OPD) by copper ions (Cu2+). Free Cu2+ can oxidize OPD into fluorescent 2,3-diaminophenzine followed by the formation of copper nanoparticles (CuNPs), which would further catalyze the oxidation of OPD. When quinolones were added, their strong binding affinity to Cu2+ inhibited the oxidase-like activity of Cu2+. So, the fluorescence intensity of the Cu2+–OPD system decreased obviously. The determination of quinolones can be achieved by using this fluorimetric assay without the use of complicated instruments and protocols. As demonstrated, this assay offered a highly sensitive readout for quinolones including nalidixic acid, cinoxacin, ciprofloxacin, and moxifloxacin in the linear ranges of 1.0–100 nM, 0.5–100 nM, 1.0–100 nM, and 0.1–100 nM, respectively. In addition, the developed assay was successfully applied to the direct analysis of quinolones in real amples. [ABSTRACT FROM AUTHOR]

Background: Solitary fibrous tumor (SFT) is an infrequent spindle cell tumor derived from mesenchymal tissue, which can manifest in diverse anatomical locations, primarily in the pleural cavity and infrequently in the central nervous system. SFT is predominantly observed in individuals aged between 40 and 50 years old, with a slightly higher occurrence in males than in females., Observations: This case report describes a female, age 15, who had migraines for 2 months prior to the diagnosis of an intracranial tumor. Computed tomography and magnetic resonance imaging showed a mass located in the right parietooccipital region with surrounding edema and a compressed right lateral ventricle. Neurosurgery was utilized to successfully remove the mass, and single intracranial fibrous tumor (grade I) was identified by postoperative pathological analysis. During an 8-month follow-up period, the patient did not experience any recurrences., Lessons: SFT is often misdiagnosed as meningioma because of their similar imaging characteristics. However, identifying the distinctive features of SFT on magnetic resonance imaging can distinguish it from meningioma and help to select appropriate treatment. The complete preoperative imaging data for this case indicated a highly vascularized tumor. Preoperative vascular embolization treatment reduced any difficulties during the subsequent tumor resection and minimized intraoperative bleeding.

Alpha-defensins are mammalian antimicrobial peptides expressed mainly by cells of myeloid lineage or small intestinal Paneth cells. The peptides are converted from inactive 8.5-kDa precursors to membrane-disruptive forms by post-translational proteolytic events. Because rhesus myeloid pro-alpha-defensin-4 (proRMAD-4((20-94))) lacks bactericidal peptide activity in vitro, we tested whether neutrophil azurophil granule serine proteinases, human neutrophil elastase (NE), cathepsin G (CG), and proteinase-3 (P3) have in vitro convertase activity. Only NE cleaved proRMAD-4((20-94)) at the native RMAD-4 N terminus to produce fully processed, bactericidal RMAD-4((62-94)). The final CG cleavage product was RMAD-4((55-94)), and P3 produced both RMAD-4((55-94)) and RMAD-4(57-94). Nevertheless, NE, CG, and P3 digests of proRMAD4 and purified RMAD-4((62-94)), RMAD-4((55-94)), and RMAD-4(57-94) peptides had equivalent in vitro bactericidal activities. Bactericidal peptide activity assays of proRMAD-4((20-94)) variants containing complete charge-neutralizing D/E to N/Q or D/E to A substitutions showed that (DE/NQ)-proRMAD-4((20-94)) and (DE/A)-proRMAD-4((20-94)) were as active as mature RMAD-4((62-94)). Therefore, proregion Asp and Glu side chains inhibit the RMAD-4 component of full-length proRMAD-4((20-94)), perhaps by a combination of charge-neutralizing and hydrogen-bonding interactions. Although native RMAD-4((62-94)) resists NE, CG, and P3 proteolysis completely, RMAD-4((62-94)) variants with disulfide pairing disruptions or lacking disulfide bonds were degraded extensively, evidence that the disulfide array protects the alpha-defensin moiety from degradation by the myeloid converting enzymes. These in vitro analyses support the conclusion that rhesus macaque myeloid pro-alpha-defensins are converted to active forms by serine proteinases that co-localize in azurophil granules.

alpha-Defensins are mediators of mammalian innate immunity, and knowledge of their structure-function relationships is essential for understanding their mechanisms of action. We report here the NMR solution structures of the mouse Paneth cell alpha-defensin cryptdin-4 (Crp4) and a mutant (E15D)-Crp4 peptide, in which a conserved Glu(15) residue was replaced by Asp. Structural analysis of the two peptides confirms the involvement of this Glu in a conserved salt bridge that is removed in the mutant because of the shortened side chain. Despite disruption of this structural feature, the peptide variant retains a well defined native fold because of a rearrangement of side chains, which result in compensating favorable interactions. Furthermore, salt bridge-deficient Crp4 mutants were tested for bactericidal effects and resistance to proteolytic degradation, and all of the variants had similar bactericidal activities and stability to proteolysis. These findings support the conclusion that the function of the conserved salt bridge in Crp4 is not linked to bactericidal activity or proteolytic stability of the mature peptide.

The alpha-defensin antimicrobial peptide family is defined by a unique tridisulfide array. To test whether this invariant structural feature determines alpha-defensin bactericidal activity, mouse cryptdin-4 (Crp4) tertiary structure was disrupted by pairs of site-directed Ala for Cys substitutions. In a series of Crp4 disulfide variants whose cysteine connectivities were confirmed using NMR spectroscopy and mass spectrometry, mutagenesis did not induce loss of function. To the contrary, the in vitro bactericidal activities of several Crp4 disulfide variants were equivalent to or greater than those of native Crp4. Mouse Paneth cell alpha-defensins require the proteolytic activation of precursors by matrix metalloproteinase-7 (MMP-7), prompting an analysis of the relative sensitivities of native and mutant Crp4 and pro-Crp4 molecules to degradation by MMP-7. Although native Crp4 and the alpha-defensin moiety of proCrp4 resisted proteolysis completely, all disulfide variants were degraded extensively by MMP-7. Crp4 bactericidal activity was eliminated by MMP-7 cleavage. Thus, rather than determining alpha-defensin bactericidal activity, the Crp4 disulfide arrangement confers essential protection from degradation by this critical activating proteinase.