Search results for "biology"
showing 10 items of 59551 documents
Modellmembranen auf Oberflächen. Verankert und doch mobil
2008
Membranmodelle, die auf Festkorperoberflachen verankert sind, ermoglichen es, elektrische Verfahren sowie oberflachenanalytische und abbildende Methoden einzusetzen. So kann mit Membranen auf Oberflachen die laterale Organisation von Lipiden und Proteinen bis in den Nanometerbereich hinein visualisiert werden. Gleichzeitig sind diese Membranen sehr stabil und damit attraktiv fur verschiedene Bereiche der Biosensorik. Durch eine individuelle Adressierung kleinster mikrometergroser Membranareale mit verschiedenen Lipidkompositionen ist es moglich geworden, die Bindung von Proteinen an funktionale Membranen auf kleinstem Raum zu quantifizieren und zu parallelisieren. Fur die Untersuchung von T…
Exploring the Chemoselectivity towards Cysteine Arylation by Cyclometallated Au III Compounds: New Mechanistic Insights
2020
To gain more insight into the factors controlling the efficient cysteine arylation by cyclometalated Au(III) complexes, the reaction between selected gold compounds and different peptides was investigated by high‐resolution liquid chromatography electrospray ionization mass spectrometry (HR‐LC‐ESI‐MS). The deducted mechanisms of C–S cross‐coupling, also supported by density functional theory (DFT) and quantum mechanics/molecular mechanics (QM/MM) calculations, evidenced the key role of secondary peptidic gold binding sites in favouring the process of reductive elimination.
Electrostatic complementarity in pseudoreceptor modeling based on drug molecule crystal structures: the case of loxistatin acid (E64c)
2015
After a long history of use as a prototype cysteine protease inhibitor, the crystal structure of loxistatin acid (E64c) is finally determined experimentally using intense synchrotron radiation, providing insight into how the inherent electronic nature of this protease inhibitor molecule determines its biochemical activity. Based on the striking similarity of its intermolecular interactions with those observed in a biological environment, the electrostatic potential of crystalline E64c is used to map the characteristics of a pseudo-enzyme pocket.
Self-assembled Pt2L2 boxes strongly bind G-quadruplex DNA and influence gene expression in cancer cells
2017
Supramolecular Pt(ii) quadrangular boxes bind native and G-quadruplex DNA motifs in a size-dependent fashion. Three Pt molecular squares of distinct size show biological activity against cancer cells and heavily influence the expression of genes known to form G-quadruplexes in their promoter regions. The smallest Pt-box displays less activity but more selectivity for a quadruplex formed in the c-Kit gene.
Montanacin-L and montanacin-K two previously non-described acetogenins from Annona montana twigs and leaves
2020
A phytochemical study on Annona montana twigs and leaves led to the isolation of eleven annonaceous acetogenins, including two previously non-described compounds, montanacin-L and montanacin-K. Their structures were elucidated by extensive analyses of spectroscopic data (IR, UV, HRTOFMS, EI-MS and 1H, 13C and 2D NMR). The ACGs montanacin-L, montanacin-K, montanacin-D and montanacin-E were evaluated for their toxicity against Spodoptera frugiperda Smith (Lepidoptera: Noctuidae). Results revealed that montanacin-D and montanacin-K exhibited insecticide action. Fil: Ruiz Hidalgo, José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; …
Herbicidal value of essential oils from oregano-like flavour species
2017
ABSTRACTChemical composition and phytotoxicity of oregano, marjoram and Thymus mastichina essential oils against Portulaca oleracea L., Lolium multiflorum Lam. and Echinochloa crus-galli (L.) Beauv. has been investigated. Seventy-seven compounds reaching 97.3% and 99.4% were identified by gas chromatography–mass spectrometry. Carvacrol (60.42 ± 0.07%), p-cymene (15.52 ± 0.02%) and γ-terpinene (5.19 ± 0.02%) were the main compounds in oregano essential oil, whereas large amounts of 1,8-cineol (59.59 ± 0.85%, 49.49 ± 0.37%), linalool (13.05 ± 0.04%, 5.66 ± 0.01%) and α-terpineol (3.36 ± 0.10%, 5.59 ± 0.01%), followed by β-pinene (4.35 ± 0.39, 5.54 ± 0.01%) and α-pinene (4.11 ± 0.53, 4.28 ± 0.…
A new polyketide from the bark of Hypericum roeperianum Schimp. (Hypericaceae)
2019
The isolation and spectroscopic data of a hitherto undescribed polyketide (1) from Hypericum roeperianum Schimp. (Hypericaceae) together with six known compounds (2–7) is herein reported. The struc...
The effect of bone marrow-derived stem cells associated with platelet-rich plasma on the osseointegration of immediately placed implants
2020
Background Stem cells associated with growth factors have been shown to improve bone healing and the osseointegration of dental implants. A Brazilian miniature pig model was used to evaluate the effect of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) associated with platelet-rich plasma (PRP) on the osseointegration of immediately placed dental implants. Material and methods A total of four male adult miniature pigs were used in this study. BM-MSCs from each pig were isolated from the iliac crest and expanded in vitro. The undifferentiated BM-MSCs were mixed with autologous PRP and implanted in the post-extraction sockets at the experimental sites before implant placement …
Analysis of salivary detection of P16INK4A and RASSF1A promoter gene methylation and its association with oral squamous cell carcinoma in a Colombian…
2019
Background Epigenetic factors play a fundamental role in the etiopathogenesis of oral squamous cell carcinoma (OSCC). This study evaluated if salivary detection of P16INK4A/RASSF1A gene promoter methylation might be linked to the clinical/histological features of OSCC in a Colombian population. Material and Methods Methylation-specific polymerase chain reaction (MSP-PCR) was used to detect the methylation frequency of P16INK4A/RASSF1A genes in DNA obtained from whole saliva collected of 40 healthy controls (HC) and 43 OSCC patients. Determination of the clinical performance of MSP-PCR assay was based on standard algorithms derived from two-way contingency table analysis. The association of …
Determination and Toxicology Studies of Quaternary Ammonium Salts in Solution after Organoclay Processing
2018
Organoclays have potential to be used as additives in various facade paints and other finishing materials. Such new innovative materials must be rigorously tested for them to have no impact on environment. Focus of this study was to develop HPLC – TOF/MS method for determining quaternary ammonium salts in various material washing solutions and to determine organoclay toxicity by performing acute toxicity test on Daphnia magna. From the obtained results, it was possible to conclude that organoclays can be safely used as additives in various materials with low or no impact on environment. We determined that organoclays are significantly less toxic then some quaternary ammonium salts on its ow…