Search results for "Assay"
showing 10 items of 2241 documents
Phytochemical characterization and antioxidant activity of the aerial part extracts from two species of Matthiola wild in Sicily: Matthiola sinuata a…
2022
As part of a project aimed at investigating the specific and intraspecific taxa of Matthiola which grow spontaneously in Sicily (Italy), in this work our research has been focused on Matthiola tricuspidata and Matthiola sinuata. The phenolic and volatile compounds of the hydroalcoholic extracts from the aerial parts of the selected species have been characterized by HPLC-PDA/ESI-MS and SPME-GC/MS analyses. Moreover, the antioxidant capacity in vitro (1,1-diphenyl-2-picrylhydrazil (DPPH), reducing power and Fe2+ chelating activity assays) and the toxicity (Artemia salina lethality bioassay) of the extracts were investigated. The phytochemical analyses highlighted quite different phenolic and…
Siderophores and related outer membrane proteins in Vibrio spp. which are potential pathogens of fish and shellfish
1991
. A total of eight reference strains and 43 environmental isolates of Vibrio species that are potential fish pathogens, were assayed for the production and utilization of siderophores. Chemical and biological assays indicated that all species produced phenolate compounds and only some strains of V. cholerae non-O1, V. parahaemolyticus and V. fluvialis produced hydroxamates. Bioassays indicated that all species produced compounds that stimulated the growth of the homologous and the heterologous species in low-iron media. The catechol-type siderophores produced may be functionally related to enterobactin as demonstrated by bioassays with enterobactin-deficient mutants. However, the chromatogr…
Gold coated porous silicon nanocomposite as a substrate for photoluminescence-based immunosensor suitable for the determination of Aflatoxin B1.
2017
Abstract A rapid and low cost photoluminescence (PL) immunosensor for the determination of low concentrations of Aflatoxin B1 (AFB1) has been developed. This immunosensor was based on porous silicon (PSi) covered by thin gold layer (Au) and modified by antibodies against AFB1 (anti-AFB1). PSi layer was formed on silicon substrate, then the surface of PSi was covered by 30 nm layer of gold (PSi/Au) using electrochemical and chemical deposition methods and in such ways PSi/Au (El.) and PSi/Au (Chem.) structures were formed, respectively. In order to find PSi/Au the most efficiently suitable for PL-based sensor design, structure several different PSi/Au (El.) and PSi/Au (Chem.) structures were…
Porous silicon based photoluminescence immunosensor for rapid and highly-sensitive detection of Ochratoxin A.
2017
A rapid and low cost photoluminescence (PL) immunosensor for the determination of low concentrations of Ochratoxin A (OTA) has been developed. This immunosensor was based on porous silicon (PSi) and modified by antibodies against OTA (anti-OTA). PSi layer was fabricated by metal-assisted chemical etching (MACE) procedure. Main structural parameters (pore size, layer thickness, morphology and nanograins size) and composition of PSi were investigated by means of X-Ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. PL-spectroscopy of PSi was performed at room temperature and showed a wide emission band centered at 680 ± 20nm. Protein A was covalently immobilized …
Separation of Nanoparticles by Gel Electrophoresis According to Size and Shape
2007
We demonstrate the separation of gold and silver nanoparticles according to their size and shape by agarose gel electrophoresis after coating them with a charged polymer layer. The separation is monitored optically using the size- and shape-dependent plasmon resonance of noble metal particles and confirmed by transmission electron microscopy (TEM). Electrophoretic mobilities are quantitatively explained by a model based on the Henry formula, providing a theoretical framework for predicting gel mobilities of polymer coated nanoparticles.
The region 0.7615-0.796 m.u. of the HSV-1 genome determines suppression of humoral antibody formation against herpes simplex virus.
1991
The influence of genetic properties of parts of the HSV-1 genome on suppression of humoral antibody formation was investigated by using intratypic recombinants. The deleted strain HFEM (HSV-1) induces suppression. The MluI DNA fragment (coordinates 0.7615–0.796 m.u.) derived from the antibody inducing strain F1 (HSV-1) was transfected into the deleted strain HFEM to produce the recombinant virus R-MlCI and shown to restore antibody formation, as demonstrated by neutralization- and ELISA-tests. The intratypic recombinant viruses R-15, R-19 and R-26, produced by transfection of the Bam HI DNA-fragment B (0.738–0.809 m.u.) of strain Fl into the deleted strain HFEM, resulted in antibody formati…
Nanosecond pulsed electric field inhibits malignant melanoma growth by inducing the change of systemic immunity
2019
Background Nanosecond pulsed electric fields (nsPEFs) showed an inhibitory effect on proliferation of malignant melanoma. In this study, the growth of melanoma were inhibited by changing the systemic immunity. Material and Methods C57BL/6 mice with B16 malignant were exposed to 200 pulses of 100 ns duration, 30kV/cm. The mice were executed four days later. T lymphocyte has been extracted from spleen. Cell viability was evaluated by CCK-8 assay. CD3+CD4+ T cells, CD3+CD8+ T cells, regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC) were analyzed by flow cytometry. TNF-α, IL-2, IL-10, TGF-β, IFN– γ levels in supernatants were assessed by ELISA. Results C57 malignant melanoma…
The mitotic kinase Aurora-A promotes distant metastases by inducing epithelial-to-mesenchymal transition in ERα+ breast cancer cells
2013
In this study, we demonstrate that constitutive activation of Raf-1 oncogenic signaling induces stabilization and accumulation of Aurora-A mitotic kinase that ultimately drives the transition from an epithelial to a highly invasive mesenchymal phenotype in estrogen receptor α-positive (ERα(+)) breast cancer cells. The transition from an epithelial- to a mesenchymal-like phenotype was characterized by reduced expression of ERα, HER-2/Neu overexpression and loss of CD24 surface receptor (CD24(-/low)). Importantly, expression of key epithelial-to-mesenchymal transition (EMT) markers and upregulation of the stemness gene SOX2 was linked to acquisition of stem cell-like properties such as the ab…
Large-scale effects of migration and conflict in pre-agricultural groups: Insights from a dynamic model.
2016
The debate on the causes of conflict in human societies has deep roots. In particular, the extent of conflict in hunter-gatherer groups remains unclear. Some authors suggest that large-scale violence only arose with the spreading of agriculture and the building of complex societies. To shed light on this issue, we developed a model based on operatorial techniques simulating population-resource dynamics within a two-dimensional lattice, with humans and natural resources interacting in each cell of the lattice. The model outcomes under different conditions were compared with recently available demographic data for prehistoric South America. Only under conditions that include migration among c…
A way to follow the viability of encapsulated Bifidobacterium bifidum subjected to a freeze-drying process in order to target the colon: Interest of …
2012
The aim of this work was to apply flow cytometry in order to assess and compare the viability of freeze-dried entrapped bacteria with an usual technique by quantification by plate count techniques. It also aimed at studying the effect of various cryoprotectants on the viability of an entrapped Bifidobacterium bifidum subjected to freeze-drying to check their ability to be delivered all along the gastro-intestinal tract. The alginate-pectinate beads were chosen as the encapsulation matrix added with different protectants. The beads were characterized by scanning electron microscopy and the viability was checked by both methods. The best combination to improve viability of entrapped bacteria …