Search results for "L-lactate"
showing 10 items of 93 documents
Influence of inorganic pyrophosphate on the kinetics of muscle pyruvate kinase: a simple nonallosteric feedback model.
2002
Potassium pyrophosphate was used instead of ATP as a model ligand for magnesium cation for the study of effector influence on the kinetics of pyruvate kinase muscle isozyme M1. The pyruvate kinase activation by low concentration of pyrophosphate and inhibition by high concentration of pyrophosphate was considered to be the result of reversible reactions of magnesium cation with pyrophosphate, ADP, ATP, and PEP. The apparent Km and Vm or in some cases the pseudo-first order reaction rate constant (instead of Km and Vm) of pyruvate kinase at any given pyrophosphate concentration were analysed as a function of concentration of free magnesium cation and its complexes with all ligands present in…
A hypothetical model of the influence of inorganic phosphate on the kinetics of pyruvate kinase
2000
This paper presents a simple solution to the problem of approximating the calculated curve of reaction progress to the measured curve which is usually disturbed by initial oscillation of auxiliary lactate dehydrogenase (LDH) reaction. The experiments leading to the determination of the apparent Km for phosphoenolpyruvate (PEP) and Vm were performed. For precise estimation of kinetic parameters (Km and Vm) of the M1 isozyme of pyruvate kinase (PK), measured by coupling it to LDH reaction, the sequence of Michaelis‐Menten for pyruvate kinase and second-order kinetics for lactate dehydrogenase reaction as well as a non-zero initial concentration of lactate was assumed. The functions of apparen…
Interactions of silica nanoparticles with lung epithelial cells and the association to flotillins
2012
Amorphous silica nanoparticles (aSNPs) gain increasing popularity for industrial and therapeutic claims. The lung with its surface area of 100-140 m(2) displays an ideal target for therapeutic approaches, but it represents also a serious area of attack for harmful nanomaterials. The exact nature of the cytotoxic effects of NPs is still unknown. Furthermore, cellular pathways and the destiny of internalized NPs are still poorly understood. Therefore, we examined the cytotoxicity (MTS, LDH) and inflammatory responses (IL-8) for different-sized aSNPs (30, 70, 300 nm) on our lung epithelial cells line NCI H441 and endothelial cell line ISO-HAS-1. Additionally, colocalization studies have been c…
Triclosan induces Fas receptor-dependent apoptosis in mouse neocortical neurons in vitro
2014
Triclosan (TCS) is a commonly used antimicrobial agent in personal care and sanitizing products, as well as in household items. Numerous studies have demonstrated the presence of TCS in various human tissues. Several studies have reported the accumulation of TCS in fish and human brain tissue. The aim of the present study was to investigate the effect of TCS on apoptosis in mouse neocortical neurons after 7 days of culture in vitro following 3, 6 and 24 h of exposure. To explore the mechanism underlying the effects of TCS in neurons, we studied the activation and protein expression of the Fas receptor (FasR) and caspase- 8, caspase-9 and caspase-3, as well as DNA fragmentation in TCS-treate…
Effects of propanil on the European eel Anguilla anguilla and post-exposure recovery using selected biomarkers as effect criteria
2008
Abstract The aim of this study was to assess the physiological response of Anguilla anguilla to propanil and the degree of recovery after being moved to clean water. Preliminary acute toxicity test was carried out in the laboratory and the median lethal concentration (LC50) at 96 h was calculated as 31.33 mg/L (29.60–33.59 mg/L). NOEC and LOEC values (at 96 h) were also calculated as 20 and 25 mg/L, respectively. The fish were exposed to 0.63 and 3.16 mg/L of propanil for 72 h and allowed to recover for 144 h. Total proteins (TPs), γ -glutamil transpeptidase ( γ -GT), alanin aminotransferase (AlAT), alkaline phosphatase (AP), lactate dehydrogenase (LDH) and water content (WC) were assayed i…
In human endothelial cells rapamycin causes mTORC2 inhibition and impairs cell viability and function.
2008
Aim Drug-eluting stents are widely used to prevent restenosis but are associated with late endothelial damage. To understand the basis for this effect, we have studied the consequences of a prolonged incubation with rapamycin on the viability and functions of endothelial cells. Methods and results Human umbilical vein or aorta endothelial cells were exposed to rapamycin in the absence or in the presence of tumour necrosis factor α (TNFα). After a 24 h-incubation, rapamycin (100 nM) caused a significant cell loss associated with the increase of both apoptosis and necrosis, as quantified by propidium iodide staining, caspase 3 activity, and lactate dehydrogenase release. Rapamycin also impair…
Fermentation Products of Commensal Bacteria Alter Enterocyte Lipid Metabolism
2020
eferred to byJia Wen, John F. RawlsFeeling the Burn: Intestinal Epithelial Cells Modify Their Lipid Metabolism in Response to Bacterial Fermentation ProductsCell Host & Microbe, Volume 27, Issue 3, 11 March 2020, Pages 314-316; International audience; Despite the recognized capacity of the gut microbiota to regulate intestinal lipid metabolism, the role of specific commensal species remains undefined. Here, we aimed to understand the bacterial effectors and molecular mechanisms by which Lactobacillus paracasei and Escherichia coli regulate lipid metabolism in enterocytes. We show that L-lactate produced by L. paracasei inhibits chylomicron secretion from enterocytes and promotes lipid stora…
Enzym-histochemische Studien am cervicalen Dr�senfeld des Uterus
1972
Durch enzym-histochemische Untersuchungen an Cervices soll Einblick in den Stoffwechsel des cervicalen Drusenfeldes gewonnen werden. Hierfur wurden insbesondere die Enzyme des Glucosestoffwechsels, der Fettsaureoxydation, des Pentosephosphatstoffwechsels, des Citronensaurecyclus sowie des NADH- und NADPH-Diaphorese-Systems und des Aminosaurestoffwechsels untersucht. Die einheitliche Nachweistechnik erlaubt in Form eines Art Screening-Tests eine Information uber die vorhandenen Aktivitaten der einzelnen Enzyme, wobei — abgesehen von einem Enzym des Glucosestoffwechsels, namlich der Alkoholdehydrogenase und des Aminosaurestoffwechsels, der Glutamatdehydrogenase — alle Fermente nachgewiesen we…
Lymphocytes from hepatic inflammatory infiltrate kill rat hepatocytes in primary culture
1990
In the last few years it has become possible in the liver to isolate lymphocytes from inflammatory infiltrates and to culture them in vitro. Most of the lymphocyte clones obtained are CD 8 + cytotoxic cells, but interactions between these lymphocytes and hepatocytes in primary culture have not been analysed previously. In this study, cloned human T lymphocytes from liver biopsies and from the peripheral blood of patients with chronic hepatitis B or primary biliary cirrhosis, after phenotypical and functional characterization into CD 8+ or CD 4+ cytotoxic lymphocytes, were activated in an antigen-independent fashion by adding either anti CD 3 or anti CD 2/R-3 monoclonal antibodies to the cel…
Possible reason for preferential damage to renal tubular epithelial cells evoked by amphotericin B
1996
An important determinant of nephrotoxicity, which is the major complication of long-term amphotericin B treatment, is dysfunction of distal tubular epithelial cells. The underlying cause for this rather selective damage to the cells is unknown. In the present investigation, it was shown that kidney epithelial cells were initially damaged by amphotericin B at concentrations of 2.5 to 10 micrograms/ml, as demonstrable by a dramatic drop in cellular K+ levels. Cells could recover from the initial toxic action of the polyene if they were kept in medium of neutral pH, and cellular K+ levels returned to normal after 6 h. However, the recovery mechanisms failed at lower pHs of 5.6 to 6.0. At low p…