Search results for "Transformation"

Transformational Teaching in Physical Education and Students’ Leisure-Time Physical Activity: The Mediating Role of Learning Climate, Passion and Sel…

2020

In the context of education, this study examined the relationship between perceiving a transformational physical education (PE) teacher and student&rsquo

Rat liver endothelial and Kupffer cell-mediated mutagenicity of polycyclic aromatic hydrocarbons and aflatoxin B1.

1990

The ability of isolated rat liver endothelial and Kupffer cells to activate benzo(a)pyrene (BP), trans-7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene (DDBP), trans-1,2-dihydroxy-1,2-dihydrochrysene (DDCH), and aflatoxin B1 (AFB1) to mutagenic metabolites was assessed by means of a cell-mediated bacterial mutagenicity assay and compared with the ability of parenchymal cells to activate these compounds. Endothelial and Kupffer cells from untreated rats were able to activate AFB1 and DDBP; DDBP was activated even in the absence of an NADPH-generating system. Pretreating the animals with Aroclor 1254 strongly enhanced the mutagenicity of the dihydrodiol, whereas the mutagenicity of AFB1 showed a sligh…

DNA binding, adduct characterisation and metabolic activation of aflatoxin B1 catalysed by isolated rat liver parenchymal, Kupffer and endothelial ce…

1991

In vitro studies with rat liver parenchymal, Kupffer and endothelial cells isolated from male Sprague-Dawley rats were undertaken to investigate cell-specific bioactivation of aflatoxin B1, DNA binding and adduct formation. In the mutagenicity studies, using homogenates of all three separated liver cell populations (co-incubated with NADP+ and glucose-6-phosphate as cofactors for the cytochrome P-450 monooxygenase system) parenchymal, Kupffer and endothelial cells were able to activate aflatoxin B1 to a metabolite mutagenic to Salmonella typhimurium TA 98. In the case of nonparenchymal cells (i.e. Kupffer and endothelial cells) 10-fold higher concentrations of aflatoxin B1 had to be used to…

Reductive and oxidative metabolism of nitrofurantoin in rat liver.

1980

The elimination of nitrofurantoin was studied in the isolated rat liver using a recirculating hemoglobin-free perfusion system. The most rapid clearance of nitrofurantoin (0.1 mM) was found under hypoxia (8 ml/min) or anoxia (11 ml/min) indicating a fast and oxygen-sensitive reductive metabolism. The hepatic elimination of nitrofurantoin under anaerobic conditions apparently is not catalyzed by xanthine oxidase, aldehyde oxidase or cytochrome P-450 as judged from the lack of influence of the inhibitors (0.1 mM) allopurinol, menadione, metyrapone, α-naphthoflavone or of carbon monoxide (50%; v/v). Under aerobic conditions the hepatic clearance of nitrofurantoin is rather low (1 ml/min) indic…

Novel Antihypertensive Lactoferrin-Derived Peptides Produced by Kluyveromyces marxianus: Gastrointestinal Stability Profile and In Vivo Angiotensin I…

2014

Novel antihypertensive peptides released by Kluyveromyces marxianus from bovine lactoferrin (LF) have been identified. K. marxianus LF permeate was fractionated by semipreparative high performance liquid chromatography and 35 peptides contained in the angiotensin I-converting enzyme (ACE)-inhibitory fractions were identified by using an ion trap mass spectrometer. On the basis of peptide abundance and common structural features, six peptides were chemically synthesized. Four of them (DPYKLRP, PYKLRP, YKLRP, and GILRP) exerted in vitro inhibitory effects on ACE activity and effectively decreased systolic blood pressure after oral administration to spontaneously hypertensive rats (SHRs). Stab…

Large differences in metabolic activation and inactivation of chemically closely related compounds: effects of pure enzymes and enzyme induction on t…

1981

Metabolic Activation of the (+)-S,S- and (−)-R,R-Enantiomers of trans-11,12-Dihydroxy-11,12-dihydrodibenzo[a,l]pyrene:  Stereoselectivity, DNA Adduct…

1997

Polycyclic aromatic hydrocarbons require metabolic activation in order to exert their biological activity initiated by DNA binding. The metabolic pathway leading to bay or fjord region dihydrodiol epoxides as ultimate mutagenic and/or carcinogenic metabolites is thought to play a dominant role. For dibenzo[a,l]pyrene, considered as the most potent carcinogenic polycyclic aromatic hydrocarbon, the formation of the fjord region syn- and/or anti-11,12-dihydrodiol 13,-14-epoxide (DB[a,l]PDE) diastereomers has been found to be the principal metabolic activation pathway in cell cultures leading to DNA adducts. In order to further elucidate the stereoselectivity involved in this activation pathway…

Characterization of DNA adducts at the bay region of dibenz[a,h]anthracene formed in vitro

1993

Bay region diolepoxide-DNA adducts of dibenz[a,h]anthracene (DBA) formed in vitro were identified and their absolute stereochemistry was assigned. After activation of [5,12-14C]DBA with liver microsomes obtained from Aroclor 1254 treated male Sprague-Dawley rats in the presence of calf thymus DNA for 1 h, the amount of DNA adducts was found to be 9.9 +/- 2.4 pmol/mg DNA, calculated on the basis of the portion of radioactivity eluted from the HPLC reversed-phase column with a water/acetonitrile gradient. Bay region diolepoxide-DNA adducts represented 27.5% of radioactivity associated with DNA adducts. The absolute configuration of the various adducts was determined from the reaction of the (…

Tumor dedifferentiation: an important step in tumor invasion.

1985

Tumor invasion in vivo was studied by light and electron microscopy as well as by immunofluorescence microscopy. Special regard was paid to the grade of tumor differentiation. Dimethylhydrazine-induced murine colonic carcinomas comprising a differentiated and an undifferentiated tumor type with low and high invasiveness respectively, were used. At the invasion front of both tumor types a striking dissociation of the organized tumor cell complexes into isolated tumor cells was found together with a loss of most of the cytological features of differentiation. It is supposed that this process mobilizes the tumor cells from the main tumor bulk enabling them to invade the host tissue by active l…

The Major Virus-Producing Cell Type during Murine Cytomegalovirus Infection, the Hepatocyte, Is Not the Source of Virus Dissemination in the Host

2008

SummaryThe course of systemic viral infections is determined by the virus productivity of infected cell types and the efficiency of virus dissemination throughout the host. Here, we used a cell-type-specific virus labeling system to quantitatively track virus progeny during murine cytomegalovirus infection. We infected mice that expressed Cre recombinase selectively in vascular endothelial cells or hepatocytes with a murine cytomegalovirus for which Cre-mediated recombination would generate a fluorescently labeled virus. We showed that endothelial cells and hepatocytes produced virus after direct infection. However, in the liver, the main contributor to viral load in the mouse, most viruses…