Search results for "Intracellular"
showing 10 items of 821 documents
At reduced temperature, endocytic membrane traffic is blocked in multivesicular carrier endosomes in rat cardiac myocytes.
1998
Temperatures around 20 degrees C are known to block degradation of endocytosed material by preventing its transport to lysosomes, accordingly reduced temperature has been widely used to define endosomes. Newer studies have revealed that the low temperature block is proximal to perinuclear late endosomes, but it is not clear whether the block is already in early endosomes, or whether the traffic proceeds to multivesicular carrier endosomes which mediate transport from early to late compartments. We have now focused on this problem using rat cardiac myocytes. First, cell fractionation on Percoll gradients showed that at reduced temperatures (22 degrees C and 26 degrees C), with prolonged chas…
Functional assays of oxidative stress using genetically engineered Escherichia coli strains.
2003
Oxidative stress may be induced in bacteria by exogenous biocidal agents and is involved in endogenous metabolism. The oxyR operon is a main sensor of oxidative stress and oxyR-deficient bacteria show enhanced sensitivity to oxidative stress and increased accumulation of intracellular reactive oxygen species (ROS). Flow cytometric functional assays in bacteria are limited by the impaired penetration of vital dyes trough the cell wall. Escherichia coli B WP2 strains possess an altered cell-wall lipopolysaccharide that leads to increased membrane permeability. Flow cytometric analysis of WP2 strains is a convenient alternative for cytometric assays of bacterial function. This unit presents pr…
Multiparametric characterization by flow cytometry of flow-sorted subpopulations of a human hepatoma cell line useful for drug research
2004
Background Primary cultured hepatocytes are the closest model to the liver for drug research. However, to overcome its limited availability, the search for hepatic cell lines as an alternative to primary cultures is a matter of current interest. In particular, highly differentiated hepatocellular carcinomas have been proposed as in vitro tools for routine experiments in hepatotoxicity and drug metabolism. Methods Cell populations were selected by fluorescence-activated cell sorting based on low and high relative expressions of P-glycoprotein. These cell lines were characterized after 21 days in culture by multiparametric analysis with flow cytometry providing direct information on key cellu…
Lack of correlation between trehalose accumulation, cell viability and intracellular acidification as induced by various stresses in Saccharomyces ce…
1998
A pma1-1 mutant of Saccharomyces cerevisiae with reduced H+-ATPase activity and the isogenic wild-type strain accumulated high levels of trehalose in response to a temperature upshift to 40 éC and after addition of 10% ethanol, but only modest levels in response to a rapid drop in external pH and after addition of decanoic acid. There was, however, no correlation between the absolute levels of trehalose in the stressed cells and their viability. All these treatments induced a significant decrease in intracellular pH, and surprisingly, this decrease was very similar in both strains, indicating that intracellular acidification could not be the triggering mechanism for trehalose accumulation i…
In vivo imaging of an elicitor-induced nitric oxide burst in tobacco
2000
A growing body of evidence suggests that nitric oxide (NO), an important signalling and defence molecule in mammals, plays a key role in activating disease resistance in plants, acting as signalling molecule and possibly as direct anti-microbial agent. Recently, a novel fluorophore (diaminofluorescein diacetate, DAF-2 DA) has been developed which allows bio-imaging of NO in vivo. Here we use the cell-permeable DAF-2 DA, in conjunction with confocal laser scanning microscopy, for real-time imaging of NO in living plant cells. Epidermal tobacco cells treated with cryptogein, a fungal elicitor from Phytophthora cryptogea, respond to the elicitor with a strong increase of intracellular NO. NO-i…
Tumour tissue monitoring during photodynamic and hyperthermic treatment using bioimpedance spectroscopy.
2003
Electrical bioimpedance spectroscopy is a fast and relatively easily applicable method for tissue characterization. In the frequency range up to 10 MHz, current conduction through tissue is mainly determined by tissue structure, i.e. the extra- and intra-cellular compartments and the insulating cell membranes. Therefore, changes in the extra- and intra-cellular fluid volumes are reflected in the impedance spectra. Investigations of tumours (DS sarcoma, implanted on the hind foot dorsum of rats) during treatment with localized hyperthermia (HT), photodynamic therapy (PDT) and the combination of these two components were carried out using impedance spectroscopy in the frequency range of 37 Hz…
The neuroprotective actions of corticotropin releasing hormone
2005
Corticotropin-releasing hormone (CRH) modulates the activity of the hypothalamic-pituitary-adrenal (HPA) axis, and has a key role in mediating neuroendocrine effects that occur in response to stressful stimuli. Disruption of the CRH system however has been shown to be closely associated with the progression of Alzheimer's disease (AD), and these observations prompted an investigation into the potential neuroprotective effects of the hormone. In addition to its regulatory affects on the molecular processes that underlie AD i.e., amyloid precursor protein (APP) processing and potentially tau phosphorylation, evidence is provided that the neuroprotective effects of CRH are mediated by a number…
Gated mesoporous silica nanoparticles for the controlled delivery of drugs in cancer cells
2015
In recent years, mesoporous silica nanoparticles (MSNs) have been used as effective supports for the development of controlled-release nanodevices that are able to act as multifunctional delivery platforms for the encapsulation of therapeutic agents, enhancing their bioavailability and overcoming common issues such as poor water solubility and poor stability of some drugs. In particular, redox-responsive delivery systems have attracted the attention of scientists because of the intracellular reductive environment related to a high concentration of glutathione (GSH). In this context, we describe herein the development of a GSH-responsive delivery system based on poly(ethylene glycol)- (PEG-)…
Enzyme-responsive silica mesoporous supports capped with azopyridinium salts for controlled delivery applications
2012
11 páginas, 7 figuras, 3 tablas y 2 esquemas
Cathepsin-B Induced Controlled Release from Peptide-Capped Mesoporous Silica Nanoparticles
2014
New capped silica mesoporous nanoparticles for intracellular controlled cargo release within cathepsin B expressing cells are described. Nanometric mesoporous MCM-41 supports loaded with safranin O (S1-P) or doxorubicin (S2-P) containing a molecular gate based on a cathepsin B target peptidic sequence were synthesized. Solids were designed to show "zero delivery" and to display cargo release in the presence of cathepsin B enzyme, which selectively hydrolyzed in vitro the capping peptide sequence. Controlled delivery in HeLa, MEFs WT, and MEFs lacking cathepsin B cell lines were also tested. Release of safranin O and doxorubicin in these cells took place when cathepsin B was active or presen…