Search results for "Trace"
showing 10 items of 3218 documents
[35] Determination of oxidized glutathione in blood: High-performance liquid chromatography
1994
Publisher Summary The measurement of glutathione status is important in determining oxidative stress in tissues and biological fluids. The ratio of reduced to oxidized glutathione (GSH/GSSG) is a good indicator of the oxidative stress that may occur under physiological and pathological conditions. Changes in GSSG levels have been considered as intracellular signals able to modulate enzyme activity. Thus, it is important to have accurate methods to determine GSSG in biological fluids and in cells. In many cases, it is possible to use tissues, such as liver, muscle, or brain to determine GSH/GSSG. However, especially in human studies, samples from these tissues are not readily available; the …
The Myristoylated Alanine-Rich C-Kinase Substrate (MARCKS) is Sequentially Phosphorylated by Conventional, Novel and Atypical Isotypes of Protein Kin…
1995
The myristoylated alanine-rich C-kinase substrate (MARCKS) is the major protein kinase C (PKC) substrate in many cell types including fibroblasts and brain cells. Here we describe the phosphorylation of MARCKS and the site specificity for different PKC isotypes. Conventional (c)PKC beta 1, novel (n)PKC delta and nPKC epsilon efficiently phosphorylated the MARCKS protein in vitro. The Km values were extremely low, reflecting a high affinity between kinases and substrate. The apparent affinity of nPKC delta (Km = 0.06 microM) was higher than that of nPKC epsilon and cPKC beta 1 (Km = 0.32 microM). The rate of substrate phosphorylation was inversely correlated with affinity and decreased in th…
Stromal Interaction Molecule 1 (STIM1) Is Involved in the Regulation of Mitochondrial Shape and Bioenergetics and Plays a Role in Oxidative Stress
2012
Calcium ions are involved in a plethora of cellular functions including cell death and mitochondrial energy metabolism. Store-operated Ca(2+) entry over the plasma membrane is activated by depletion of intracellular Ca(2+) stores and is mediated by the sensor STIM1 and the channel ORAI1. We compared cell death susceptibility to oxidative stress in STIM1 knock-out and ORAI1 knockdown mouse embryonic fibroblasts and in knock-out cells with reconstituted wild type and dominant active STIM1. We show that STIM1 and ORAI1 deficiency renders cells more susceptible to oxidative stress, which can be rescued by STIM1 and ORAI1 overexpression. STIM1 knock-out mitochondria are tubular, have a higher Ca…
Molecular basis of early epithelial response to streptococcal exotoxin: role of STIM1 and Orai1 proteins
2011
Streptolysin O (SLO) is a cholesterol-dependent cytolysin (CDC) from Streptococcus pyogenes. SLO induces diverse types of Ca(2+) signalling in host cells which play a key role in membrane repair and cell fate determination. The mechanisms behind SLO-induced Ca(2+) signalling remain poorly understood. Here, we show that in NCI-H441 cells, wild-type SLO as well as non-pore-forming mutant induces long-lasting intracellular Ca(2+) oscillations via IP(3) -mediated depletion of intracellular stores and activation of store-operated Ca(2+) (SOC) entry. SLO-induced activation of SOC entry was confirmed by Ca(2+) add-back experiments, pharmacologically and by overexpression as well as silencing of ST…
The iron-regulatory hormone hepcidin: A possible therapeutic target?
2015
The maintenance of stable extracellular and intracellular iron concentrations requires the coordinated regulation of iron transport into plasma. Iron is a fundamental cofactor for several enzymes involved in oxidation-reduction reactions. The redox ability of iron can lead to the production of oxygen free radicals, which can damage various cellular components. Therefore, the appropriate regulation of systemic iron homeostasis is decisive in vital processes. Hepcidin has emerged as the central regulatory molecule of systemic iron homeostasis. It is synthesized in hepatocytes and in other cells and released into the circulation. It inhibits the release of iron from enterocytes of the duodenum…
Twenty Years of Airborne Water Vapor and Total Water Measurements of a Diode Laser Based Photoacoustic Instruments
2020
We present relevant issues collected over twenty years of development and operation of an airborne water vapour / total water detector based on photoacoustic spectroscopy. The WaSulHygro instrument possesses high selectivity, short response time, and wide dynamic range, that are key requirements against trace gas measurement systems for applications in atmospheric sciences. Besides the major properties of WaSul-Hygro we discuss our efforts to develop a robust instruments that have proved its long-term reliability over the last fifteen years operating on-board a commercial aircraft within the framework of the CARIBIC project.2
A discourse on human hair fibers and reflections on the conservation of drug molecules
1996
A gross discourse on human hair fibers and their formation is presented stressing the various interdisciplinary aspects, such as the morphological, biological, structural and biochemical data considered to be important in the field of hair analysis. An attempt is made to explain the incorporation of drug molecules during hair fiber formation by using the classical concepts of drug absorption based on lipoid theory and the pH-partition hypothesis as well as a modern biological approach on the permeability of cell membranes. In addition to the physiochemical considerations of the transport properties of a particular drug molecule such as a) the lipophilicity, which determines permeability thr…
PET Imaging of the Impact of Extracellular pH and MAP Kinases on the p-Glycoprotein (Pgp) Activity
2012
The functional activity of p-glycoprotein (Pgp) can be increased in vitro by an extracellular acidosis via activation of MAP kinases (p38, ERK1/2). In order to study these effects in vivo a new (68)Ga-labeled PET tracer was developed which serves as a substrate of the Pgp and therefore indirectly mirrors the Pgp activity. For in vivo studies, experimental tumors were imaged under acidic conditions (inspiratory hypoxia, injection of lactic acid) and during inhibition of MAP kinases in a μ-PET system. In vitro, [(68)Ga]MFL6.MZ showed an accumulation within the cells of about 20% which was increased to 30% by Pgp inhibition. In solid tumors a marked tracer uptake was observed showing spatial h…
Golgi Fragmentation in Neurodegenerative Diseases: Is There a Common Cause?
2019
In most mammalian cells, the Golgi complex forms a continuous ribbon. In neurodegenerative diseases, the Golgi ribbon of a specific group of neurons is typically broken into isolated elements, a very early event which happens before clinical and other pathological symptoms become evident. It is not known whether this phenomenon is caused by mechanisms associated with cell death or if, conversely, it triggers apoptosis. When the phenomenon was studied in diseases such as Parkinson’s and Alzheimer’s or amyotrophic lateral sclerosis, it was attributed to a variety of causes, including the presence of cytoplasmatic protein aggregates, malfunctioning of intracellular traffic and/or alterations i…
Modeling of intracellular transport in realistic cell geometries
2018
The transport of molecules inside cells is a complex process, the characterization of which is important to gain full understanding of cellular processes. Understanding of intracellular transport is also important for medical applications, for example when analyzing transport of medicine inside cells. The intracellular environment is very complex, and at least the most crucial parts of this complexity must be accounted for to solve transport problems in cells. In this thesis the results of studies in modeling intracellular transport are presented. The aim of the work was to model intracellular transport of proteins and viral capsids in realistic cell environments. To this end, microscopic m…