Antifungal activities of D0870 against fluconazole-resistant Candida albicans.
(57/3718)
We compared the in vitro and in vivo antifungal activities of D0870, a new triazole antifungal agent, with those of other antifungal agents against 8 clinical isolates of fluconazole-resistant Candida albicans. Microdilution testing was performed according to National Committee for Clinical Laboratory Standards (NCCLS) document M27-T. Minimal inhibitory concentration of D0870 (<0.004-1.0 micro g/ml) was lower than those of fluconazole (2->64 microEg/ml) and itraconazole (0.031-8.0 microEg/ml). In systemic infection models with C. albicans in normal and immunosuppressed mice, D0870 at 0. 3-30 mg/kg/day for 5 days after infection prolonged survival of the animals and showed the highest efficacy among the triazole antifungal agents. At pH 7 and 37C in Sabouraud dextrose broth (SDB), D0870 inhibited the growth of C. albicans and acted cytocidally against one of the middle-resistant strains. In an in vivo study against this strain, D0870 at 10 mg/kg/day for 5 days after infection significantly reduced kidney colony counts (2850+406-997+537 CFU/kidney, P<0.05) on day 7 after infection in comparison with those of the control mice at 24 h after infection. Plasma concentration of D0870 after a single oral administration at 10 mg/kg maintained a sufficient level for interpretation of in vivo antifungal activities. These results suggest that D0870 has strong antifungal activities against clinical isolates of fluconazole-resistant C. albicans in vitro and in vivo, and that these strong activities are at least partially concerned with the fungicidal action. (+info)
Motility induced by human immunodeficiency virus-1 Tat on Kaposi's sarcoma cells requires platelet-activating factor synthesis.
(58/3718)
In the present study, we evaluated whether motility of Kaposi's sarcoma (KS) spindle cells induced by HIV-1 Tat protein is dependent on the synthesis of platelet-activating factor (PAF). The results obtained indicate that Tat induced a dose-dependent synthesis of PAF from KS cells at a concentration as low as 0.1 ng/ml. PAF production started rapidly after Tat stimulation, peaking at 30 minutes and declining thereafter. Tat-induced cell migration was also a rapid event starting at 30 minutes. The motility was abrogated by addition of a panel of chemically unrelated PAF receptor antagonists (WEB 2170, CV 3988, CV 6209, and BN 52021), suggesting that the synthesized PAF mediates the motogenic effect of Tat. This effect was also present on cells plated on a type-I collagen-, fibronectin-, or basement membrane extract-coated surface. Expression of PAF receptor-specific mRNA was detected in KS cells. In addition, examination of the cytoskeletal organization showed that Tat-mediated KS cell redistribution of actin filaments and shape change was also inhibited by a PAF receptor antagonist. Moreover, PAF receptor blockade prevented the up-regulation of beta1 integrin and the down-regulation of alphavbeta3 observed after stimulation of KS cells with Tat. In conclusion, the results of the present study indicate that Tat-induced PAF synthesis plays a critical role in triggering the events involved in motility of KS cells. (+info)
In-vitro activity of voriconazole (UK-109,496), LY303366 and other antifungal agents against oral Candida spp. isolates from HIV-infected patients.
(59/3718)
In this report we compare the activity of two new antifungal agents, voriconazole (UK-109,496) and LY303366 with the activities of other antifungals including fluconazole, itraconazole, 5-fluorocytosine (5FC) and amphotericin B against 219 oral Candida spp. isolates from HIV-infected patients. We used the broth microdilution method following the guidelines of the NCCLS. The in-vitro activity of voriconazole (UK-109,496) (MIC(90) 0.12 mg/L) and LY303366 (CMI(90) 0.25 mg/L) against clinical isolates of Candida spp. was excellent and comparable with that of amphotericin B (MIC(90) 0.5 mg/L), and better than those of fluconazole (MIC(90) > or = 64 mg/L), itraconazole (MIC(90) 4 mg/L) and 5FC (MIC(90) 1 mg/L). (+info)
The anticonvulsant BW534U87 depresses epileptiform activity in rat hippocampal slices by an adenosine-dependent mechanism and through inhibition of voltage-gated Na+ channels.
(60/3718)
1. The cellular and molecular actions of BW534U87 were studied using intracellular and extracellular recordings from the CA1 region of rat hippocampal slices and whole-cell voltage-clamp recordings of recombinant human brain type IIA Na+ channels expressed in Chinese hamster ovary (CHO) cells. 2. Normal excitatory and inhibitory postsynaptic potentials evoked in hippocampal slices were unaffected by BW534U87 or the adenosine deaminase inhibitor EHNA. However, epileptiform activity was depressed by BW534U87 (50 micronM) and this inhibition was reversed by the adenosine receptor antagonist 8-phenyl theophylline (8-PT, 30 micronM). EHNA (10 micronM) mimicked the effects of BW534U87. Furthermore, BW534U87 enhanced the inhibitory effects of exogenous adenosine on evoked synaptic potentials. BW534U87 (50 micronM) also voltage- and use-dependently inhibited action potentials elicited by current injection, independent of the adenosine system, since it was not affected by 8-PT. 3. In CHO cells expressing the recombinant human brain Na+ channel, BW534U87 produced a concentration- and voltage-dependent inhibition of Na+ currents with a half-maximal inhibitory concentration of 10 micronM at a Vh of -60 mV. Use-dependent inhibition was evident at high-frequencies (20x20 ms pulse train at 10 Hz). 4 In conclusion, BW534U87 blocks hippocampal epileptiform activity by a dual mechanism. The first action is similar to that produced by EHNA and is dependent on endogenous adenosine probably by inhibition of adenosine deaminase. Secondly, BW534U87 directly inhibits voltage-gated Na+ channels in a voltage- and frequency-dependent manner. Both actions of BW534U87 are activity-dependent and may synergistically contribute to its overall anticonvulsant effects in animal models of epilepsy. (+info)
Effect of A2A adenosine receptor stimulation and antagonism on synaptic depression induced by in vitro ischaemia in rat hippocampal slices.
(61/3718)
1. In the present study we investigated the role of A2A adenosine receptors in hippocampal synaptic transmission under in vitro ischaemia-like conditions. 2. The effects of adenosine, of the selective A2A receptor agonist, CGS 21680 (2-[p-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamidoade nos ine ), and of selective A2A receptor antagonists, ZM 241385 (4-(2-[7-amino-2-(2-furyl)- inverted question mark1,2,4 inverted question mark-triazolo inverted question mark2,3-a inverted question mark inverted question mark1,3, 5 inverted question marktriazin-5-ylamino]ethyl)phenol) and SCH 58261 (7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2, 4-triazolo[1,5-c]pyrimidine), have been evaluated on the depression of field e.p.s.ps induced by an in vitro ischaemic episode. 3. The application of 2 min of in vitro ischaemia brought about a rapid and reversible depression of field e.p.s.ps, which was completely prevented in the presence of the A1 receptor antagonist DPCPX (1, 3-dipropyl-8-cyclopentylxanthine) (100 nM). On the other hand both A2A receptor antagonists, ZM 241385 and SCH 58261, by themselves did not modify the field e.p.s.ps depression induced by in vitro ischaemia. 4. A prolonged application of either adenosine (100 micronM) or CGS 21680 (30, 100 nM) before the in vitro ischaemic episode, significantly reduced the synaptic depression. These effects were antagonized in the presence of ZM 241385 (100 nM). 5. SCH 58261 (1 and 50 nM) did not antagonize the effect of 30 nM CGS 21680 on the ischaemia-induced depression. 6. These results indicate that in the CA1 area of the hippocampus the stimulation of A2A adenosine receptors attenuates the A1-mediated depression of synaptic transmission induced by in vitro ischaemia. (+info)
Mechanosensitive properties of gastric vagal afferent fibers in the rat.
(62/3718)
Single, teased fiber recordings were made from the decentralized right cervical vagus nerve (hyponodal) of the rat. A total of 67 afferent fibers that responded to gastric distension (GD) were studied: 9 fibers were stimulated by phasic balloon GD, 58 by more natural fluid GD. All balloon GD-responsive fibers had resting activity (3.1 imp/s), and 57/58 fluid GD responsive fibers had resting activity (1.3 imp/s). All balloon GD-responsive fibers exhibited a dynamic response to phasic distension followed by slow adaptation, whereas fluid GD-responsive fibers exhibited increasing responses as intragastric pressure increased, followed typically by slow adaptation. Responses to graded GD were studied in all fibers, and all gave increasing responses to increasing pressures (5-60 mmHg). Thresholds for response varied between 0 and 18 mmHg. Mean response thresholds for two durations of fluid GD (30 and 60 s) were 5.6 and 3.9 mmHg; the mean response threshold to phasic balloon GD (30 s duration) was 5.3 mmHg. The potential sensitizing effect of platelet activating factor (PAF, 50 or 100 ng. kg(-1). min(-1) for 20 min) infused into the gastric artery was studied in 20 fibers. Fifteen fibers exhibited an increase in spontaneous activity; intragastric pressure also slightly increased during PAF infusion. The increase in activity produced by PAF was attenuated in the presence of the PAF receptor antagonist WEB 2086. After PAF-induced acute inflammation of the stomach, three of five fibers studied did not exhibit any change in response to graded GD. The present study characterized distension-sensitive afferent fibers in the right cervical vagus innervating the stomach of the rat by balloon GD and fluid GD. The results document that all distension-sensitive gastric vagal afferent fibers encoded the intensity of GD, but none had response thresholds in what might be considered the noxious range. PAF infusion activated mechanosensitive gastric vagal afferent fibers, but acute inflammation produced by PAF did not sensitize responses to GD. (+info)
Adenosine inhibits a non-inactivating K+ current in bovine adrenal cortical cells by activation of multiple P1 receptors.
(63/3718)
1. Bovine adrenal zona fasciculata (AZF) cells express a non-inactivating K+ current (IAC) that sets the resting potential while it is activated by intracellular ATP. In whole-cell patch clamp recordings from bovine AZF cells, we found that adenosine selectively inhibited IAC by a maximum of 78.4 +/- 4.6 % (n = 8) with an IC50 of 71 nM. The non-selective adenosine receptor agonist NECA effectively inhibited IAC by 79.3 +/- 2.9 % (n = 24) at a concentration of 100 nM. 2. Inhibition of IAC was mediated through multiple P1 adenosine receptor subtypes. The A1-selective agonist CCPA (10 nM), the A2A-selective agonist CGS 21680 (100 nM) and the A3-selective agonist IB-MECA (10 nM) inhibited IAC by 64.8 +/- 8.4, 78.4 +/- 4.6 and 69.3 +/- 6.9 %, respectively. 3. Specific adenosine receptor subtype antagonists including DPCPX (A1), ZM 241385 (A2A) and MRS 1191 (A3) effectively blocked inhibition of IAC by adenosine receptor-selective agonists. 4. A mixture of the three adenosine receptor antagonists completely suppressed inhibition of IAC by adenosine, but failed to alter inhibition by external ATP which acts through a separate P2 nucleotide receptor. 5. Inhibition of IAC by adenosine or NECA was eliminated by substituting GDP-beta-S for GTP in the pipette, or by replacing ATP with AMP-PNP or UTP. 6. In addition to inhibiting IAC, adenosine (10 microM) depolarized AZF cells by 46.2 +/- 5.8 mV (n = 6). 7. These results show that bovine AZF cells express at least three adenosine receptor subtypes (A1, A2A, A3), each of which is coupled to the inhibition of IAC K+ channels through a G-protein-dependent mechanism requiring ATP hydrolysis. Adenosine-mediated inhibition of IAC is associated with membrane depolarization. Adenosine and other purines may co-ordinate the stress-induced secretion of corticosteroids and catecholamines from the adrenal gland. (+info)
Microdilution susceptibility testing of amphotericin B, itraconazole, and voriconazole against clinical isolates of Aspergillus and Fusarium species.
(64/3718)
We compared the activities of amphotericin B, itraconazole, and voriconazole against clinical Aspergillus (n = 82) and Fusarium (n = 22) isolates by a microdilution method adopted from the National Committee for Clinical Laboratory Standards (NCCLS-M27A). RPMI 1640 (RPMI), RPMI 1640 supplemented to 2% glucose (RPMI-2), and antibiotic medium 3 supplemented to 2% glucose (AM3) were used as test media. MICs were determined after 24, 48, and 72 h. A narrow range of amphotericin B MICs was observed for Aspergillus isolates, with minor variations among species. MICs for Fusarium isolates were higher than those for Aspergillus isolates. MICs of itraconazole were prominently high for two previously defined itraconazole-resistant Aspergillus fumigatus isolates and Fusarium solani. Voriconazole showed good in vitro activity against itraconazole-resistant isolates, but the MICs of voriconazole for F. solani were high. RPMI was the most efficient medium for detection of itraconazole-resistant isolates, followed by RPMI-2. While the significance remains unclear, AM3 lowered the MICs, particularly those of amphotericin B. (+info)