Search results for "STRAINS"
showing 10 items of 589 documents
Differential effect of insulin and epidermal growth factor on the mRNA translocation system and transport of specific poly(A+) mRNA and poly(A-) mRNA…
1990
The efficiency of efflux of rapidly labeled poly(A)-containing mRNA from isolated rat liver nuclei was found to be modulated by insulin and epidermal growth factor (EGF) in a biphasic but opposite way. At physiological concentrations (10 pM insulin and 1 pM EGF), maximal stimulation of the transport rate by insulin (to 137%) and maximal inhibition by EGF (to 69%) were obtained; at higher concentrations (greater than 100 pM and greater than 10 pM, respectively), the amount of poly(A)-containing mRNA released into the postnuclear supernatant was nearly identical with the level found in untreated nuclei (= 100%). Using mRNA entrapped into closed nuclear envelope (NE) vesicles as a model system…
Proteins from rat liver cytosol which stimulate mRNA transport. Purification and interactions with the nuclear envelope mRNA translocation system.
1986
Two polysome-associated proteins with particular affinities for poly(A) have been purified from rat liver. These proteins stimulate the efflux of mRNA from isolated nuclei in conditions under which such efflux closely stimulates mRNA transport in vivo, and they are therefore considered as mRNA-transport-stimulatory proteins. Their interaction with the mRNA-translocation system in isolated nuclear envelopes has been studied. The results are generally consistent with the most recently proposed kinetic model of mRNA translocation. One protein, P58, has not been described previously. It inhibits the protein kinase that down-regulates the NTPase, it enhances the NTPase activity in both the prese…
Genetically engineered V79 chinese hamster cell expression of purified cytochromeP-450iib1 monooxygenase activity
1989
Chinese hamster V79 fibroblasts, frequently used as target cells in short-term tests for mutagenicity, do not possess measurable monooxygenase activity; in particular, enzymatic oxidation of testosterone (T) cannot be demonstrated. If these V79 cells, however, had been transfected with the cDNA-encoding rat liver cytochrome P-450IIB1 under control of the SV40 early promoter, they stably expressed monooxygenase activity. These so-called SD1 cells then oxidatively metabolized T at a rate of 27 pmol/mg protein/min, converting it to 16 alpha- and 16 beta-hydroxy-T as well as 4-androsten-3,17-dione as sole metabolites in a ratio of 1.1:1.0:1.6. The regio- and stereoselective conversion of T by S…
Near fatal percutaneous paraquat poisoning
1983
A fatal paraquat poisoning can occur when relatively large areas of skin are contaminated with a concentrated solution of paraquat (Gramoxone). A paraquat absorption takes place of the same magnitude as that with an equal dose per os. In the presence of mechanical or chemical lesion of the skin the percutaneous paraquat absorption is distinctly enhanced.
Morphometric and cytophotometric nuclear analysis of altered hepatocyte foci induced by N-nitrosomorpholine (NNM) and aflatoxin B1 (AFB1) in liver of…
1987
The progressive morphological changes in the liver during neoplastic transformation have been studied by histological, cytophotometric and morphometric methods in male Wistar rats treated with two carcinogens: N-nitrosomorpholine (NNM) and aflatoxin B1 (AFB1). Cytophotometric and morphometric analysis of hepatocyte nuclei using Feulgen-stained tissue sections were performed in morphologically normal hepatic parenchyma and in early preneoplastic foci composed of altered hepatocytes. Foci of clear cells, mixed cells and large basophilic cells possessed a ploidy distribution similar to the surrounding non-transformed parenchyma, while the small hyperbasophilic cell foci were predominantly dipl…
In-vivo confocal real-time mini-microscopy in animal models of human inflammatory and neoplastic diseases
2007
Background and study aims Although various improvements in tissue imaging modalities have recently been achieved, in-vivo molecular and subsurface imaging in the field of gastroenterology remains a technical challenge. In this study we evaluated a newly developed, handheld, miniaturized confocal laser microscopy probe for real-time in-vivo molecular and subsurface imaging in rodent models of human disease. Materials and methods The minimicroscope uses a 488-nm, single line laser for fluorophore excitation. The optical slice thickness is 7 microm, the lateral resolution 0.7 microm. The range of the z-axis is 0-250 microm below the tissue surface. Imaging was performed using different fluores…
Morphology and chronology of ischemic mucosal changes in the small intestine
1983
The morphology and chronology of an absolute ischemia was investigated on the small intestine of man and rat. It could be shown that the morphogenesis of ischemic damage to the intestinal mucosa in man does not differ from that in the rat. However, there are crucial and in therapeutic terms significant differences in the time course of the ischemic damage to the intestinal mucosa. Whereas in the small intestine of the rat, the first appreciable alterations - detachment and disruption of the lining epithelium at the villous tip - are already to be observed after absolute ischemia lasting 15 min, in the human small intestine the same lesions only occur after 4 h. A comparable complete necrosi…
Comparison of the effects of valproate, ethosuximide, phenytoin, and pentobarbital on cerebral energy metabolism in the rat.
1987
The acute effects of valproate (200 and 400 mg/kg), ethosuximide (200 and 400 mg/kg), phenytoin (25 and 50 mg/kg), and pentobarbital (30 and 60 mg/kg) on cerebral energy metabolism of rats were studied by measuring the cerebral content of energy metabolites and by evaluating the rate of metabolite utilization following decapitation. The treatments did not affect the levels of phosphocreatine (PCr), ATP, ADP, and AMP, but did enhance the glycogen or glucose stores. Pentobarbital induced a decrease in lactate, whereas valproate led to a decrease in pyruvate and an increase in lactate. Calculation of the metabolite fluxes after decapitation showed that all treatments delayed the rate of ATP ut…
Day/night changes of pineal gland volume and pinealocyte nuclear size assessed over 10 consecutive days
1984
Previous studies aimed at elucidating day/night changes of pineal gland size and pinealocyte nuclear volume have yielded contradictory results. The aim of the present investigation was to examine the above parameters over a period of 10 successive days, at 6-hour intervals under a lighting regimen of LD 12:12 (7 a.m. to 7 p.m.). It was found that changes in pineal gland volume could not be correlated with the light/dark phases; instead, a rhythm with a two-day period was encountered. Pinealocyte nuclear volume, by contrast, showed clear circadian changes, exhibiting troughs during photophase and peaks during scotophase. In this experimental series, the karyometric results conformed to the m…
Non-linear Intestinal Absorption Kinetics of Cefadroxil in the Rat
1989
Abstract Absorption of Cefadroxil in a selective intestinal absorption area (the proximal third of the small intestine) of the anaesthetized rat, at seven initial perfusion concentrations, ranging from 0·01 to 10·0 mg mL−1, is shown to be a non-linear transport mechanism. With the aid of computer-fitting procedures based on differential and integrated forms of Michaelis-Menten equation, Vm and Km values of 36·7–37·3 mg h−1 and 12·0–13·0 mg, respectively, were found. The statistical parameters were better than those obtained both for first-order and for combined Michaelis-Menten and first-order kinetics. There is no evidence for substantial passive diffusion processes. The results reported h…