Search results for "ACTIVATION"
showing 10 items of 2079 documents
In vitro generated human memory-like T cells are CD95 type II cells and resistant towards CD95-mediated apoptosis
2006
An adaptive immune response implies expansion of activated T cells and subsequent elimination to maintain homeostasis in a process called activation-induced cell death. Some cells, however, differentiate into memory cells and ensure a strong secondary immune response. To analyze the apoptosis phenotype of memory T cells on a cellular and molecular level, we have established an in vitro model of T cell activation and generation of cells phenotypically and functionally similar to memory cells. These long-term cultured T cells show a CD95-resistant phenotype, although they are still sensitive towards TCR/CD3-mediated apoptosis. Biochemical analysis revealed that these cells shift from CD95 typ…
Depletion of delta 9 desaturase (EC 1.14.99.5) activity in lactating rat during protein restriction.
2000
The effects of protein restriction on the activity of delta9 desaturase (EC 1.14.99.5) were investigated in lactating rats. A control group was fed a balanced diet (20% casein) for 14 days, whereas the experimental groups were fed a low-protein diet (8% casein), supplemented with or without L-methionine (0.4%), for 14 days. The enzyme activity was measured by incubations of hepatic microsomal pellets with (1-14C) stearic acid. Results showed a decreased delta9 desaturase activity, after 2,7 and 14 days of depleted diet, of -50, -40 and -33% respectively, compared with control. The supplementation of the low-protein diet with 0.4% methionine, which favours food consumption as well as growth,…
Influence of spontaneous hypertension on n-3 delta-6-desaturase activity and fatty acid composition of rat hepatocytes.
1995
The first and rate limiting step in the conversion of alpha-linolenic acid is catalyzed by the delta-6-desaturase enzyme. The activity of such an enzyme was studied in order to investigate the n-3 Polyunsaturated Fatty Acid biogenesis during hypertension. Rat isolated hepatocyte n-3 delta-6-desaturase activity was higher in 1 month old Spontaneously Hypertensive Rats — prehypertensive period- as compared to normotensive Wistar Kyoto rats, whereas there was no significant difference at 12 months — hypertensive period-. Our data indicate no correlation between the directly measured enzyme activity and the changes in hepatocyte n-3 fatty acid compositions. The loss of hepatocyte n-3 delta-6-de…
Oxidative stress induces the expression of the major histocompatibility complex in murine tumor cells.
2001
The effect of t-butyl hydroperoxide (t-BOOH) on the induction of the Major Histocompatibility Complex (MHC) class I genes has been studied in two cell clones (B9 and G2) of the methylcholanthrene-induced murine fibrosarcoma GR9. These two clones were selected based on their different biological and biochemical behavior specially related to their tumor induction capability when injected into a BALB/c mouse. t-BOOH (0.125 mM) induced the expression of H-2 molecules in both cell clones. In B9 cell clone, in which MHC basal expression is very low or absent, t-BOOH significantly induced H-2Kd, H-2Dd and H-2Ld molecules. In G2 cell clone the expression of MHC class I genes was also enhanced by th…
The role of metallothionein and selenium in metal detoxification in the liver of deep-sea fish from the NW Mediterranean Sea
2014
8 pages, 1 figure, 5 tables
Structural and functional diversity of the lectin repertoire in teleost fish: Relevance to innate and adaptive immunity
2011
Protein–carbohydrate interactions mediated by lectins have been recognized as key components of innate immunity in vertebrates and invertebrates, not only for recognition of potential pathogens, but also for participating in downstream effector functions, such as their agglutination, immobilization, and complement-mediated opsonization and killing. More recently, lectins have been identified as critical regulators of mammalian adaptive immune responses. Fish are endowed with virtually all components of the mammalian adaptive immunity, and are equipped with a complex lectin repertoire. In this review, we discuss evidence suggesting that: (a) lectin repertoires in teleost fish are highly dive…
Using the Hermite Regression Formula to Design a Neural Architecture with Automatic Learning of the “Hidden” Activation Functions
2000
The value of the output function gradient of a neural network, calculated in the training points, plays an essential role for its generalization capability. In this paper a feed forward neural architecture (αNet) that can learn the activation function of its hidden units during the training phase is presented. The automatic learning is obtained through the joint use of the Hermite regression formula and the CGD optimization algorithm with the Powell restart conditions. This technique leads to a smooth output function of αNet in the nearby of the training points, achieving an improvement of the generalization capability and the flexibility of the neural architecture. Experimental results, ob…
Continuous flow synthesis of amine oxides by oxidation of tertiary amines
2019
The synthesis of N-methylmorpholine N-oxide by oxidation of N-methylmorpholine with hydrogen peroxide was implemented in a microstructured reactor for increased safety and larger-scale applications. The active oxidant, peroxymonocarbonate HCO4− is formed in situ from the equilibrium reaction of hydrogen peroxide and bicarbonate. The bicarbonate can be induced by hydration of carbon dioxide. Elaborate studies on the influence of the catalyst concentration and temperature were carried out and the observed activation energy was determined. Elevated temperatures up to 60 °C and a carbon dioxide concentrations of 1 wt% led to a conversion for N-methylmorpholine of approximately 98% within 13.90 …
Steam catalytic cracking of naphtha over ZSM-5 zeolite for production of propene and ethene: Micro and macroscopic implications of the presence of st…
2012
One option to produce more ethene and propene can be to crack naphtha type fractions in dedicated smaller FCC units. We present here the results obtained for high temperature steam catalytic cracking (SCC) of a representative naphtha product (n-heptane) with ZSM-5. It has been found that under those conditions the presence of steam produces an irreversible dealumination of the zeolite as well as a reversible deactivation due to the interaction of water with active sites with a negative effect on protolytic cracking. A kinetic decay model that takes into account the two phenomena has been developed. The apparent activation energy is lower in the presence of steam. It appears that whilst the …
Viscosity Arrhenius parameters correlation: extension from pure to binary fluid mixtures
2015
Knowledge of fluids’ physicochemical properties is mandatory for the design and optimisation of industrial processes and products. A data quantity of most importance, in this regard, turns out to be the value of fluid viscosity. Many empirical and semi-empirical formulas have been proposed in the literature to describe the viscosity of pure liquids and binary liquid mixtures. Recently, an interesting equation is proposed for pure solvents correlating the two parameters in the viscosity Arrhenius-type equation, namely the activation energy (Ea) and the pre-exponential factor (As). This paper aims to extend the said correlation to binary liquid mixtures. To achieve this purpose, statistical m…