Search results for "trains"

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…

Conflict-behaviour and temporal discrimination performance in the rat: Comparison between alprazolam and various conventional benzodiazepines

1990

The effects of phorbol esters on choline phospholipid hydrolysis in heart and brain

1990

The efflux of choline was determined in rat striatal slices, incubated chicken atria and perfused chicken hearts. 4 beta-Phorbol-12 beta,13 alpha-dibutyrate (PDB) and 4 beta-phorbol-12 beta-myristate, 13 alpha-acetate (PMA) were used to stimulate protein kinase C. The other phorbol esters, 4 beta-phorbol-13 alpha-acetate (PAc) and 4 alpha-phorbol-12 beta,13 alpha-didecanoate (4 alpha PDD), known to be inactive, were tested to evaluate the specificity of the responses. PDB markedly enhanced the efflux of choline in all of the three preparations. The PDB-evoked efflux of choline in incubated chicken atria was equal to the net production of choline and, therefore, was not caused by translocati…

Characteristics of lysosomal phosphomannosyl-enzyme receptors in the rat heart

1987

The receptor system recognizing mannose 6-phosphate groups of lysosomal enzymes has been characterized, e.g. in fibroblasts and liver cells. The purpose of this study was to demonstrate the presence of a phosphomannosyl receptor system in rat heart muscle. The characterization of receptors was accomplished with beta-N-acetylglucosaminidase (beta-GA) secreted by rat embryo fibroblasts after ammonium chloride stimulation. The receptor binding of ligand enzymes was saturated by adding increasing concentrations of beta-GA and the binding increased linearly when the content of membrane protein was increased. The binding of beta-GA was inhibited by mannose and glucose phosphates, especially manno…

Association of a polyuridylate-specific endoribonuclease with small nuclear ribonucleo-proteins which had been isolated by affinity chromatography us…

1983

Immunoglobulins, containing antibodies against U1-snRNP, have been prepared from a patient with systemic lupus erythematosus. After coupling these antibodies to a Sepharose matrix, U-snRNPs have been isolated and purified from rat liver nuclei by use of immunoaffinity chromatography. The resulting RNPs had the typical protein pattern of U-sn RNPs and a sedimentation coefficient of 12 S. The U-snRNP preparation was associated with an endoribonuclease which required Mg2+ for optimal activity. The enzyme, with an pH optimum of 6.2, degraded only poly(U). Other single-stranded polyribo- and polydeoxyribonucleotides, tRNA, as well as double-stranded RNA and DNA were not digested. The products of…

Use of monoclonal and polyclonal antibodies as structural and topographical probes for hepatic epoxide hydrolase

1983

AbstractMonoclonal antibodies have been prepared against rat liver epoxide hydrolase (EH), some of which gave precipitation lines on immunodiffusion against pure EH suggesting the presence of repetitive structural domains on the enzyme. Using ELISA, with polyclonal antibodies to rat and rabbit liver EH, reactivity and therefore structural similarities between EH of all species tested, including human, were observed. This was in contrast to immunodiffusion results demonstrating the limitations of the latter technique. Using monoclonal antibodies in ELISA, greatest structural similarity was between rat, mouse, and Syrian hamster EH and relatively little between rat and human. Two of the antib…

Endurance training decreases the alkaline proteolytic activity in mouse skeletal muscles.

1984

Alkaline and myofibrillar protease activities of rectus femoris, soleus, and tibialis anterior muscles and the pooled sample of gastrocnemius and plantaris muscles were analyzed in male NMRI-mice during a running-training program of 3, 10, or 20 daily 1-h sessions. The activity of citrate synthase increased during the endurance training, reflecting the increased oxidative capacity of skeletal muscles. The activities of alkaline and myofibrillar proteases continually decreased in the course of the training program in all muscles studied. Instead, the activity of beta-glucuronidase (a marker of lysosomal hydrolases) increased in all muscles. The highest activities were observed at the beginni…

The major isozyme of rat cardiac glutathione transferases. Its correspondence to hepatic transferase X.

1986

1. A major isozyme of rat heart glutathione transferase was purified to homogeneity by Sephadex G-200 gel filtration, ammonium sulfate precipitation, CM-cellulose chromatography and affinity chromatography on S-hexylglutathione-linked Sepharose 6B. 2. The purified isozyme was a dimer with an apparent relative molecular mass of 50000 composed of two Yb-size subunits (Mr= 26 500). The isozyme is immunologically related to rat liver glutathione transferase X and 3–3, especially closely to transferase X, and no immunological cross-reactivity with subunits 1 and 2 of hepatic glutathione transferases was observed. The isoelectric point (pI = 6.9) of the isozyme was identical with and the substrat…