Search results for "STRAINS"
showing 10 items of 589 documents
Development and validation of a radioimmunoassay for serum melatonin.
1989
A radioimmunoassay using N-[3-(4-hydroxy-3-[4-hydroxy-3- [125I]iodophenylpropionyl)]-5-methoxytryptamine as tracer for determination of melatonin in the serum of different species is described. Melatonin antisera were raised in rabbits by immunization with a bovine serum albumin conjugate of N-[3-(2-aminoethyl)-5-methoxy indole] hemisuccinamide. A single high affinity, specific antiserum was obtained. In contrast to previous studies, the tracer was synthesised in one step in the absence of water, giving an excellent yield of highly pure product. No chromatographic purification step was needed. Polyethylene glycol in combination with goat antirabbit immunoglobulins was used to separate bound…
Influence of melatonin and serotonin on the number of rat pineal ?synaptic? ribbons and spherules in vitro
1985
Previous studies have shown that the "synaptic" ribbons (SR) and spherules (SS) of the mammalian pineal gland may respond differently under physiological and various experimental conditions. The aim of the present study was to gain insight into the mechanisms that may be responsible for the numerical changes of these organelles during a 24-h cycle. As the possibility exists that the structures are influenced by substances synthesized within the pinealocyte, rat pineal glands were cultured with and without added melatonin or serotonin, using an experimental protocol such that the addition of melatonin and serotonin mimicks the circadian changes of the respective substances within the pineal.…
Adolescent pre-exposure to ethanol or MDMA prolongs the conditioned rewarding effects of MDMA
2011
Adolescents often take ethanol (EtOH) in combination with MDMA (3,4-methylenedioxymethylamphetamine). In the present work we studied the effect of repeated intermittent adolescent pre-exposure to both drugs on the behavioral and neurochemical effects of MDMA in mice. Sixteen days after pre-treatment, the rewarding and reinstating effects of MDMA in the conditioned place preference (CPP) paradigm were evaluated, along with the levels of biogenic amines, basal motor activity and corticosterone response to different challenges. Pre-exposure to EtOH, MDMA or EtOH+MDMA did not affect the CPP induced by 10mg/kg of MDMA. However, adolescent exposure to EtOH or MDMA increased the duration of the co…
Effect of legume grains as a source of dietary protein on the quality of organic lamb meat.
2011
BACKGROUND: This study evaluated the effects on lamb growth, carcass traits and meat quality of replacing conventional soybean meal in the diet with alternative legume grains. RESULTS: Twenty-eight male lambs of Comisana breed weighing 16.9 ± 2.7 kg at weaning (66 ± 6 days old) were assigned to one of four diets. Until slaughter at 129 ± 6 days of age, each group received ad libitum pelleted alfalfa hay and concentrates differing in the source of protein: chickpea, faba bean, pea or soybean meal. Lambs fed chickpea showed higher dry matter and protein intakes from concentrate than those fed soybean. Lambs' growth, carcass weight and net dressing percentage did not vary by protein source, al…
Vitamin K epoxide reductase activity in the metabolism of epoxides
1985
Abstract The importance of vitamine K epoxide reductase for the metabolism of a range of structurally diverse epoxides has been investigated. Vitamin K 1 epoxide is reduced by rat liver microsomes at a rate of 0.47 nmoles/g liver/min. The rate of menadione oxide reduction is not significantly higher than the non-enzymatic reduction rate. No measurable reduction of benzo[ a ]pyrene 4,5-oxide, benzo[ a ]pyrene 7,8-oxide, phenanthrene 9,10-oxide, styrene 7,8-oxide, and dieldrin has been detected, nor could trichothecene T-2 toxin inhibit reduction of vitamin K 1 epoxide. Thus, vitamin K epoxide reductase is very specific for vitamin K 1 epoxide. Taking into account the range of structurally di…
Bisdihydrodiols, rather than dihydrodiol oxides, are the principal microsomal metabolites of tumorigenic trans-3,4-dihydroxy-3,4-dihydrodibenz[a,h]an…
1994
Several studies on metabolism and biological activity of tumorigenic dibenz[a,h]anthracene (DBA) and its derivatives have led to the conclusion that the M-region dihydrodiol, trans-3,4-dihydroxy-3,4-dihydro-DBA (DBA-3,4-dihydrodiol), is the precursor of the ultimate mutagenic and tumorigenic metabolite of DBA with the presumed structure of a bay-region dihydrodiol oxide. Incubations of DBA-3,4-dihydrodiol (50 microM) with the microsomal hepatic fraction of Sprague-Dawley rats pretreated with Aroclor 1254 yielded more than 13 metabolites upon separation by HPLC. anti-3,4-Dihydroxy-1,2-epoxy-1,2,3,4-tetrahydro-DBA [0.27 nmol/(nmol of P450.15 min)] could be identified for the first time by UV …
Enzymatic and pharmacokinetic studies on the metabolism of branched chain alpha-keto acids in the rat.
1983
Michaelis-constants and enzyme activities for dehydrogenation and transamination of the three branched chain alpha-keto acids in liver, kidney, skeletal muscle, and brain of rats are reported. After oral load only 11-22% of the keto acids pass the liver unchanged. Blood levels in pharmacokinetic and absorption studies are related to the Michaelis-constants. At the low keto-acid concentrations after oral application, dehydrogenation in the non-hepatic tissues is supposed to prevail over transamination. Data on feed efficiency of branched chain alpha-keto acids reported in the literature support this view. The chance for transamination is better after intravenous administration. The transfera…
Sulfotransferase-mediated chlorination of 1-hydroxymethylpyrene to a mutagen capable of penetrating indicator cells.
1990
Methylated polycyclic aromatic hydrocarbons are common in the human environment. Many of them are stronger carcinogens than their purely aromatic congeners. They may be metabolized to benzylic alcohols. We report here on biochemical and toxicological characteristics of 1-hydroxymethylpyrene (HMP), a typical representative of this class of compounds. Rat liver cytosol, fortified with 3'-phosphoadenosine-5'-phosphosulfate, converted HMP into its sulfate ester (HMPS), HMPS bound covalently to isolated DNA. In physiological buffer at 37 degrees C, HMPS had a half-life of 2 min, the major decomposition product being HMP. Thus, cyclic activation is possible. When Cl- anions were present at physio…
gd T cells condition dendritic cells in vivo for priming pulmonary CD8 T cell responses against Mycobacterium tuberculosis
2006
gammadelta T cells and dendritic cells are quickly recruited to the lungs shortly after intranasal vaccination with BCG, but the functional in vivo interplay between these two cell populations and its role in the induction of adaptive immune responses is unclear. Using TCR-deficient mice and bone marrow chimeras, we show here that gammadelta T cells provide a non-redundant early source of IFN-gamma in vivo, which enhances IL-12 production by lung dendritic cells. The in vivo-conditioned dendritic cells, in turn, prime a more efficient lung CD8 T cell response against Mycobacterium tuberculosis. Thus, strategies exploiting gammadelta T cell function and IFN-gamma production could be valuable…
Epitope specificity and Ia restriction of T cell responses to insulin in a system of complementing Ir genes: analysis with primed lymph node T cells …
1983
The antibody response of (H-2b X H-2k)F1 mice to pig insulin (PI) has previously been shown to be under the control of H-2-linked, complementing Ir genes. In addition, this response was reported to depend on the genetic background of the parental strains (Keck, K., Eur. J. Immunol. 1977. 7: 811). Here it is demonstrated that the secondary in vitro response of proliferating T cells shows the same dependence on H-2-linked Ir genes yet an influence of the background genes could not be detected. The complementing genes were mapped to the Kb, I-Ab and Kk, I-Ak regions. For restimulation of F1 T cells by PI, the Ir genes of both parental chromosomes have to be expressed in the same antigen-presen…