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1.
2.
Nitric oxide synthesis in the CNS endothelium and macrophages differs in its sensitivity to inhibition by arginine analogues. 总被引:9,自引:0,他引:9
L E Lambert J P Whitten B M Baron H C Cheng N S Doherty I A McDonald 《Life sciences》1991,48(1):69-75
Inhibition of nitric oxide production by arginine analogues was examined in three cell systems; macrophages, CNS tissue and endothelial cells. Nitric oxide production was assessed indirectly using in vitro assays measuring nitrite production (macrophages), cGMP elevation (CNS) and acetylcholine-induced relaxation of aortic ring segments (endothelium). NG-monomethyl-L-arginine and NG-amino-L-arginine possessed similar inhibitory activity in all three assays, while NG-nitro-L-arginine displayed a striking selectivity for inhibition of brain and endothelial cell nitric oxide synthesis, with IC50 values of 0.05 microM in the CNS versus 200 microM in macrophages. These results suggest that distinct enzymes are responsible for nitric oxide synthesis in different cell types, and indicate that it may be possible to selectively modulate nitric oxide production in vivo. 相似文献
3.
When carrot cell cultures, after growth in semicontinuous culture, were transferred to media containing excess nutrients, they grew at different rates. The growth rates were generally higher after semicontinuous culture at higher dilution rates. There appears to be a limit on dilution rate above which growth rate does not increase. These changes were also displayed by clones from the parental culture. The possibility that these changes in growth rate reflect a need for the cultures to adapt to their new conditions is discussed. The growth rates of the cultures is markedly increased at 25 degrees C compared with 22 degrees C with little further increase at 28 degrees C. Growth rate is altered by less than 20% when pH is changed from 4.5 to either 5.5 or 4.2. The rates of anthocyanin accumulation by the cultures were similar under all conditions tested except at 22 degrees C. They were larger than the rates of dry weight accumulation. In contrast, the amounts of anthocyanin accumulated in the clones and in the parental cultures grown at pH 5.5 instead of pH 4.5 were very different. The observations were interpreted as showing that the clones differ in the rate of metabolism but not in the rate of synthesis of anthocyanins and that at pH 5.5 the rate of metabolism of anthocyanins but not the rate of synthesis is higher than it is at pH 4.5. The use of semicontinuous cultures as a source of inoculum for batch cultures rather than as a source of biomass for extraction of chemicals is discussed. 相似文献
4.
The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds. 相似文献
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6.
Hrushikesh S. Chaudhari Omkar S. Palkar KM Abha Mishra Kalyan K. Sethi 《Journal of biochemical and molecular toxicology》2023,37(9):e23417
During the period of COVID-19, the occurrences of mucormycosis in immunocompromised patients have increased significantly. Mucormycosis (black fungus) is a rare and rapidly progressing fungal infection associated with high mortality and morbidity in India as well as globally. The causative agents for this infection are collectively called mucoromycetes which are the members of the order Mucorales. The diagnosis of the infection needs to be performed as soon as the occurrence of clinical symptoms which differs with types of Mucorales infection. Imaging techniques magnetic resonance imaging or computed tomography scan, culture testing, and microscopy are the approaches for the diagnosis. After the diagnosis of the infection is confirmed, rapid action is needed for the treatment in the form of antifungal therapy or surgery depending upon the severity of the infection. Delaying in treatment declines the chances of survival. In antifungal therapy, there are two approaches first-line therapy (monotherapy) and combination therapy. Amphotericin B ( 1 ) and isavuconazole ( 2 ) are the drugs of choice for first-line therapy in the treatment of mucormycosis. Salvage therapy with posaconazole ( 3 ) and deferasirox ( 4 ) is another approach for patients who are not responsible for any other therapy. Adjunctive therapy is also used in the treatment of mucormycosis along with first-line therapy, which involves hyperbaric oxygen and cytokine therapy. There are some drugs like VT-1161 ( 5 ) and APX001A ( 6 ), Colistin, SCH 42427, and PC1244 that are under clinical trials. Despite all these approaches, none can be 100% successful in giving results. Therefore, new medications with favorable or little side effects are required for the treatment of mucormycosis. 相似文献
7.
A reevaluation of floral and vegetative morphology together with data from analysis of floral fragrance and flavonoid co-pigment
chemistry suggest that specific status is warranted for the two kinds ofPhalaenopsis violacea Witte known informally as the “Bornean type” and the “Malayan type.”Phalaenopsis violacea var.bellina Rchb.f. is elevated to specific rank, providing a name for the “Bornean type” plants. 相似文献
8.
The accumulation of anthocyanin by clones and subclones from a cell suspension culture of wild carrot (Daucus carota L.) has been measured under standard conditions. Clones which accumulate low amounts of anthocyanin were shown, by recloning after maintenance by serial passage, to have become heterogenous and to contain cells with increased accumulation of anthocyanin. There appears to be a maximum amount of anthocyanin that clones can accumulate. Clones which accumulate the maximum amount of anthocyanin were shown by recloning after maintenance by serial passaging, to have become heterogenous and to contain many cells which accumulate less than the maximum possible amount of anthocyanin. When clones which accumulate the maximum amount of anthocyanin are maintained by serial passage, the decline in anthocyanin accumulation is different in different media. The results indicate that the changes in the ability of cells to accumulate anthocyanin involve no qualitative change in the genetic information of the cells, i.e., the changes are not the consequence of mutations. 相似文献
9.
W. Mark Whitten 《American journal of botany》1981,68(3):435-442
Monarda didyma L. and M. clinopodia L. occasionally form introgressive populations in the mountains of eastern Tennessee and western North Carolina. Monarda didyma produces large red scentless nectar-rich flowers and is pollinated primarily by the Ruby-throated Hummingbird (Archilochus colubris [Linnaeus]). The smaller, white, scented flowers of Monarda clinopodia produce small amounts of nectar and are pollinated mainly by bumblebees (Bombus spp.). The two species are highly interfertile and have strongly overlapping flowering periods. Differences in pollinator sets and pollinator constancy appear to be only partial barriers to hybridization. Lack of suitable habitats for the establishment of hybrid progeny might be the most important isolating mechanism between the two species. 相似文献
10.
Cytochrome P-448 (mol wt 55,000 Daltons) from rabbit liver was purified to a specific content of 16.6 nmol/mg. Mice were immunised with this preparation, their spleens removed and dissociated lymphocytes hybridised with myeloma cells. Four monoclonal antibodies against cytochrome P-448 were raised and partially characterised. All four antibodies interacted with cytochrome P-448 in intact microsomal fractions and selectively immunoadsorbed cytochrome P-448 from solubilised microsomal preparations. One of the antibodies inhibited benzo[a] pyrene hydroxylase activity in a reconstituted system, one had no effect on activity and two increased activity. The possible applications of such antibodies are discussed. 相似文献