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781.
Kitchen AM O'Leary DS Scislo TJ 《American journal of physiology. Heart and circulatory physiology》2006,290(2):H807-H812
We have previously shown that activation of P2X purinoceptors in the subpostremal nucleus tractus solitarius (NTS) produces a rapid bradycardia and hypotension. This bradycardia could occur via sympathetic withdrawal, parasympathetic activation, or a combination of both mechanisms. Thus we investigated the relative roles of parasympathetic activation and sympathetic withdrawal in mediating this bradycardia in chloralose-urethane anesthetized male Sprague-Dawley rats. Microinjections of the selective P2X purinoceptor agonist alpha,beta-methylene ATP (25 pmol/50 nl and 100 pmol/50 nl) were made into the subpostremal NTS in control animals, after atenolol (2 mg/kg i.v.), a beta1-selective antagonist, and after atropine methyl bromide (2 mg/kg i.v.), a muscarinic receptor antagonist. The bradycardia observed with activation of P2X receptors at the low dose of the agonist is mediated almost entirely by sympathetic withdrawal. After beta1-adrenergic blockade, the bradycardia was reduced to just -5.1 +/- 0.5 versus -28.8 +/- 5.1 beats/min in intact animals. Muscarinic blockade did not produce any significant change in the bradycardic response at the low dose. At the high dose, both beta1-adrenergic blockade and muscarinic blockade attenuated the bradycardia similarly, -37.4 +/- 6.4 and -40.6 +/- 3.7 beats/min, respectively, compared with -88.0 +/- 11 beats/min in control animals. Double blockade of both beta1-adrenergic and muscarinic receptors virtually abolished the response (-2.5 +/- 0.8 beats/min). We conclude that the relative contributions of parasympathetic activation and sympathetic withdrawal are dependent on the extent of P2X receptor activation. 相似文献
782.
783.
It was shown that dihydroxyacetone phosphate may exist in both monomeric DHAP (C3H7O6P) and dimeric DHAP-dimer (C6H14O12P2) form. Monomeric DHAP was obtained in the form of four crystalline salts: CaCl(DHAP)·2.9H2O (7a), Ca2Cl3(DHAP)·5H2O (7b), CaCl(DHAP)·2H2O (7c), and CaBr(DHAP)·5H2O (7d) by crystallization from aqueous solutions containing DHAP acid and CaCl2 or CaBr2, or by direct crystallization from a solution containing DHAP precursor and CaCl2. At least one of the salts is stable and may be stored in the crystalline state at room temperature for several months. The dimeric form was obtained by slow saturation of free DHAP syrup with ammonia at −18 °C and isolated in the form of its hydrated diammonium salt (NH4)2(DHAP-dimer)·4H2O (8). The synthesis of the compounds, their crystallization, and crystal structures determined by X-ray crystallography are described. In all 7a-d monomeric DHAP exists in the monoanionic form in an extended (in-plane) cisoid conformation, with both hydroxyl and ester oxygen atoms being synperiplanar to the carbonyl O atom. The crucial structural feature is the coordination manner, in which the terminal phosphate oxygen atoms act as chelating as well as bridging atoms for the calcium cations. Additionally, the DHAP monoanions chelate another Ca2+ by the α-hydroxycarbonyl moiety, in a manner observed previously in dihydroxyacetone (DHA) calcium chloride complexes. In dimeric 8 the anion is a trans isomer with the dioxane ring in a chair conformation with the hydroxyl groups in axial positions and the phosphomethyl group in an equatorial position. 相似文献
784.
Elżbieta Bonda-Ostaszewska Tadeusz Włostowski Alicja Krasowska Paweł Kozłowski 《Acta theriologica》2012,57(4):289-294
Seasonal changes in lipid droplet size and lipid peroxidation in the brown adipose tissue (BAT) of wild bank voles were examined. In addition, a role of photoperiod in these changes was studied; bank voles were held from the birth under long photoperiod (LP) for 12 weeks, and then half of them was transferred to short photoperiod (SP) for 6 weeks and another one remained under LP. In the wild bank voles the absolute BAT weight was seasonally constant, while the significant differences in the lipid droplet size were observed. The smallest lipid droplets (mean, 11 μm2) were seen in winter; they increased by 30 % in spring and reached the highest size (24 μm2) in summer. Lipid peroxidation in the BAT did not differ significantly between the seasons, although high intraseason variation of this process was noted. The laboratory experiment revealed that the size of lipid droplets was determined by photoperiod; SP induced 13-fold decrease, and continuous exposure to LP brought about a further 2.5-fold increase in the size of lipid droplets. Conversely, a significant decrease in lipid peroxidation was seen in LP bank voles in comparison with the SP animals. The data indicate that short photoperiod is responsible for the small size of lipid droplets in the BAT of bank voles during winter, which may be a necessary requirement for high thermogenic capacity of the tissue. Photoperiod appears also to affect lipid peroxidation in the BAT of these animals. 相似文献
785.
Tadeusz Penczak 《Environmental Biology of Fishes》1999,54(3):237-252
We compared post- and pre-introduction data for the upper Pilica River and its tributaries to investigate the impact of introduced non-native brown trout on native fish communities. Extirpations of species were recorded. More changes concerned differences in abundance and distribution in the investigated rivers rather than extirpations. Human stressors (pollution, regulation) obviously helped the invasion of trout. Repeated introduction to one tributary of the Pilica enabled brown trout to survive for 10 years, despite the presence of pike and the recent appearance of domestic pollution. 相似文献
786.
Costs and benefits for phytophagous myrmecophiles: when ants are not always available 总被引:1,自引:0,他引:1
Costs and benefits in mutualistic associations between ants and phytophagous myrmecophiles are context dependent. We collected information from the literature on costs and benefits of myrmecophily in aphids, coccids, membracids and lycaenids. A key result of the literature survey is that investment in mutualism with ants entails costs paid not only when ants are present (direct costs) but also when they are absent (indirect costs). We incorporated such a trade-off in a model that investigates the fitness consequences of the decision of a potential myrmecophile whether or not to invest in cooperation with ants. The model shows that whether myrmecophily should be favoured depends on the rate of increase of the population, and, if there are indirect costs, on the frequency of habitats with ants. Both direct and indirect costs can limit or prevent the evolution of myrmecophily even when ants are abundant. To understand the patterns of associations in the field we therefore need to measure the benefits and costs of myrmecophily both in the presence and in the absence of ants. 相似文献
787.
Aleksandra Wysocka Karolina Mann Henryk Bursig Juliusz Dec Tadeusz S. Gaździk 《Cell and tissue banking》2010,11(2):209-215
Autologous chondrocyte implantation has been shown to be a promising method for treatment of deep articular cartilage defects.
The hyaline cartilage formed by implanted autologous chondrocytes has biomechanical properties similar to those of natural
articular cartilage. Between June 2006 and September 2008 we performed Autologous chondrocyte implantation (ACI) in 50 patients
and the chondrocytes were supported in fibrin glue. The cartilage biopsy samples were taken from the non-weight bearing area
of the patient’s femoral condyle and the samples were transferred to the cell culture laboratory. Chondrocyte were kept in
culture about 20 days. Fibrin glue was used as a three dimensional carrier for chondrocyte implantation. A 450 ml of patient’s
own blood was collected prior to transplantation to produce autologous fibrinogen. Alternatively the allogenic fibrinogen
was prepared from Regional Blood Center voluntary donors. Before surgery the chondrocyte suspension was mixed with fibrin
glue and gel—like fibrograft was prepared. The total number of cells and the size of fibrograft depended on the defect size
in the knee. Our results suggest that ACI technique with fibrin glue is a promising method for treatment of cartilage defect. 相似文献
788.
Shuzo Urata Jacqueline Weyer Nadia Storm Yukiko Miyazaki Petrus Jansen van Vuren Janusz Tadeusz Paweska Jiro Yasuda 《Journal of virology》2016,90(6):3257-3261
The recently identified arenavirus Lujo virus (LUJV) causes fatal hemorrhagic fever in humans. We analyzed its mechanism of viral release driven by matrix protein Z and the cell surface glycoprotein precursor GPC. The L domains in Z are required for efficient virus-like particle release, but Tsg101, ALIX/AIP1, and Vps4A/B are unnecessary for budding. LUJV GPC is cleaved by site 1 protease (S1P) at the RKLM motif, and treatment with the S1P inhibitor PF-429242 reduced LUJV production. 相似文献
789.
Tadeusz Zwierzyński Andrzej Joachimiak MirosŁawa Barciszewska Katarzyna Kulińska Jan Barciszewski 《Chemico-biological interactions》1982,42(1):107-116
The effect of the alkaloid sparteine on arginyl-tRNA formation was studied. It was demonstrated that sparteine sulfate in the concentration range 10–60 mM inhibits the charging reaction when amino acid, ATP and tRNA are used as variable substrates. The mode of action is different for all substrates studied. It was concluded that at high sparteine concentration the pattern of inhibition for all varied substrates is generally uncompetitive. A non-competitive mechanism for amino acid and tRNA was observed at low sparteine concentration, but in the case of ATP it is also uncompetitive. 相似文献
790.