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991.
Sinikka Vainiotalo Antti Zitting Sven Jacobsson Juha Nickels Heimo Koskinen Heikki Savolainen 《Archives of toxicology》1984,55(2):137-142
Polymethylmethacrylate was thermally degraded in air at 300° C and the volatile decomposition products studied with gas chromatography-mass spectrometry. The main product was monomeric methacrylate, although many other compounds existed among the products. Electron spin resonance spectroscopy revealed the presence of free radicals. Wistar rats were exposed to the fumes of the plastic (300° C) and their lungs and brain studied for biochemical effects. In the lung, the activity of 7-ethoxycoumarin O-deethylase decreased and an initial inhibition of glutathione peroxidase and superoxide dismutase was observed. The contents of reduced nonprotein sulfhydryl groups were decreased in the lung and brain. The exposures enhanced the activities of acetylcholine esterase, creatine kinase and NADPH-diaphorase in the brain. Scanning electron microscopy of the exposed lungs showed disorganization of ciliated cells, and the epithelial serous cells (Clara cells) were damaged. 相似文献
992.
Abstract: The interferons (IFNs) have become accepted therapy in a range of haematological and non-haematological malignancies. The mechanism behind IFN's antitumour action is, however, unclear. Interferons (IFNs) are capable of modulating a variety of cellular responses. One prominent effect of IFNs is their cell growth inhibitory activity, which has also been suggested to be of major importance in their antitumour action. In the present review we will discuss the cellular events leading to a decreased number of cells following IFN treatment, the molecular mechanisms underlying these phenomena, and the importance of these effects in a clinical perspective. 相似文献
993.
Mogens Joost Larsen Ejgil Kirkegaard Sven Poulsen Ole Fejerskov 《Community dentistry and oral epidemiology》1989,17(4):204-206
The aim of the present study was to describe the intraoral pattern of dental fluorosis among fluoride tablet consumers. One hundred and forty-two children, of whom 56 had participated in a fluoride tablet program of 0.5/1.0 mg NaF per day were examined blindly for possible fluoride-induced enamel changes. A low prevalence of dental fluorosis was found among non-participants. The later in life the tooth was formed, the higher was the prevalence. The subjects who had participated in the fluoride tablet program showed a significantly higher prevalence of fluorosis. They could be divided into three groups: Group 1 exhibited a tooth prevalence pattern not statistically different from that of the non-participants, group 2 showed dental fluorosis in almost all teeth except in those formed before the start of the tablet program. In group 3 the early and the late formed teeth showed very little fluorosis while those formed in the few years just after the initiation of the fluoride tablet intake were affected by fluorosis. 相似文献
994.
Sven Björkman Jonas åkeson Fritiof Nilsson Kenneth Messeter Bodil Roth 《Journal of pharmacokinetics and pharmacodynamics》1992,20(6):637-652
Mass balance pharmacokinetics, with simultaneous blood sampling from an artery and the internal jugular vein, was used to characterize the cerebral uptake of ketamine, norketamine, and midazolam in normoventilated pigs. Intravenous injections of ketamine or midazolam decreased the cerebral blood flow (CBF)by one third, as measured by intermittent
133Xewashout. By means of pharmacodynamic models, the effects on the CBFcould be predicted from the arterial drug concentrations. The high-resolution CBFvs. time curves thus generated allowed the calculation of cerebral drug levels from arteriovenous concentration gradients in spite of a continuously changing regional blood flow. By their effects on the CBF,ketamine and midazolam decreasetheir own rateof transport to the brain, the immediate 30-35% drops in CBFgiving similar reductions in initial net influx of drug. Physiological pharmacokinetic models assuming a constant regional blood flow are therefore not appropriate. Under clinical conditions, the CBFis determined mainly by the effects of the anesthetics and by the arterial CO
2
tension. CBFchanges in either direction influence the transport of drugs to the brain and may consequently result in impaired or exaggerated drug effects.The study was supported by grants from the Swedish Medical Research Council (B91-14X-00084-27A), the Medical Faculty at Lund University, Malmö General Hospital, The Tore Nilsson Foundation for Medical Research, Warner-Lambert Scandinavia AB, Roche-Produkter AB, and the Laerdal Foundation for Acute Medicine. 相似文献
995.
Gregory A. Helm Charles G. diPierro Patricia E. Palmer Nathan E. Simmons Sven O.E. Ebbesson 《Brain research bulletin》1996,39(2):83-87
The retinal afferents to the basal optic nucleus in the frog, Rana Pipiens, were labeled anterogradely with biocytin and subsequently studied at the electron microscopic level. Labeled synaptic terminals in the nucleus varied in size from 0.5 μm to 2.0 μm and made symmetric synaptic contacts with large and small dendrites, although very rare axospinous and axosomatic contacts were also demonstrated. 相似文献
996.
Abstract: The 5-HT1A and the DA D2 receptor agonists 8-OH-DPAT (0.05–3.2 mg kg–1 subcutaneously, –20 min.) and quinpirole (0.08–1.25 mg kg–1 subcutaneously, –20 min.), respectively, both partially antagonized reserpine-induced (5 mg kg–1 subcutaneously, –16 hr) suppression of spontaneous motor activity in the rat. Four different aspects of the spontaneous motor activity were recorded in a photocell-equipped open-field (8x8 photocells, 90 mm apart, defining two horizontal planes): locomotor activity (all photocell counts at the lower level); rearing (all photocell counts at the upper level); forward locomotion (the proportion movements across the arena); peripheral activity (the proportion locomotor activity as picked up by the photocell beam closest to the wall, i.e. 25 mm). As denned by these variables, the pattern of activity produced by 8-OH-DPAT or quinpirole were indistinguishable, The effects produced by 8-OH-DPAT were fully antagonized by the 5-HT1 antagonist (–) pindolol (4 mg kg–1 subcutaneously, –30 min.), but not by the DA D2 receptor antagonist raclopride (2 mg kg–1 subcutaneously, –30 min.) nor by the 5-HT2 receptor antagonist ritanserin (2 mg kg–1 subcutaneously, –30 min.), whereas effects produced by quinpirole were fully antagonized by raclopride (2 mg kg–1 subcutaneously, –30 min.). Effects produced by quinpirole, but not 8-OH-DPAT, were potentiated by administration of the DA D1 agonist SKF-38,393 (3 mg kg–1 subcutaneously, –20 min.). It is concluded that effects by 8-OH-DPAT on spontaneous motor activity in the reserpine treated rat primarily are due to stimulation of postsynaptic 5-HT1A receptors. 相似文献
997.
This report describes a patient who suffered from several complaints, which by herself were attributed to her amalgam fillings. Analysis of mercury in plasma and urine showed unexpectedly high concentrations. 63 and 223 nmol/l. respectively. Following removal of the amalgam fillings, the urinary excretion of mercury became gradually normalized, and her symptoms declined. 相似文献
998.
Sven Edelfors 《Basic & clinical pharmacology & toxicology》1981,48(1):61-64
Abstract: Rats were fed a lithium-containing diet for five weeks (40 mmol LiCl/kg fodder). Plasma lithium concentration was 0.44 mmol Li+/1 plasma. The synaptosomes were isolated and incubated with 3H-glucosamine for 60 min. The glycopeptides and the gangliosides were extracted and the sialic acid content and the 3H-sialic acid content were measured. The lithium treatment produced an increase in the synaptosomal glycopeptide content. The sialic acid content was simultaneously increased in glycopeptides as well as gangliosides. The specific activity of sialic acid was reduced to 75% of the control value in the sialoglycopeptide fraction. 相似文献
999.
The effects of alaproclate and zimeldine on memory retrieval were examined in male Swiss Webster mice using a one-trial inhibitory avoidance task. All drugs were administered IP prior to the retention test 24 h after training. Both drugs were found to facilitate memory retrieval significantly in a dose-and time-dependent fashion that could not be explained in terms of non-specific effects of the drug (illness, lack of motility, etc.) at the time of the test. The temporal effects of alaproclate and zimeldine on memory closely followed their course of concentration of the drug within the blood stream. The facilitation of retrieval induced by alaproclate and zimeldine was blocked by the putative serotonergic receptor agonist quipazine but not blocked by the antagonist cyproheptadine. Pretreatment with quipazine alone in a group of animals trained to a shock level which normally results in high levels of suppression was not sufficient to produce memory impairment, suggesting that quipazine was probably antagonizing the facilitative effects of alaproclate and zimeldine directly, rather than overriding the facilitation through an indirect action on retrieval in general. The present results lend further support to the suggestion that serotonin plays a significant role in memory. 相似文献
1000.
Undetectable levels of circulating interferon were found in 35 splenectomized patients and in 14 controls. In addition, no differences in virus, purified protein derivative (PPD), and phytohaemagglutinin (PHA) induced interferon production were observed between the patients and the controls. Virus induced lymphocyte transformation tended to be reduced after splenectomy, but only the herpes simplex virus (HSV) induced transformation index was significantly reduced in splenectomized patients without residual splenic tissue (P < 0.05). In contrast, the PHA lymphocyte transformation was unchanged in patients and controls. The number of natural viral antibodies in splenectomized patients did not differ from that of controls. Furthermore, there were no major differences in the magnitude of the titers of the sero-positive cases between the various groups. Thus, splenectomy does not interfere with interferon production in vitro, and as seen from natural viral antibodies, no impairment of humoral immunity was observed. The reduced HSV lymphocyte transformation may indicate an impaired lymphocyte function after splenectomy. 相似文献