Revised RNA2 sequence of the tetravirus, Nudaurelia capensis omega virus (NomegaV). Annotated Sequence Record.
Explore the source record for details and available documents.
Animal Diseases↗
Biomedical subjects
M Appel
Publications and source records attributed to M Appel.
Study of the toxicity of a new lipid complex formulation of amphotericin B.
OBJECTIVES: The aim of this study was to evaluate the toxicity of a new lipid complex formulation of amphotericin B (LC-AmB) produced by a simple process. METHODS: Toxicity was evaluated after daily administration for 21 consecutive days in female CD1 mice. Doses of LC-AmB up to 20 mg/kg were used, and compared with Fungizone at 0.5 mg/kg and Abelcet at 10 mg/kg. Acute toxicity after a single bolus injection was also determined, as well as the haemolytic activity and toxicity to mouse macrophages in vitro. RESULTS: LC-AmB reduced both the haemolytic activity of amphotericin B and its toxicity towards mouse peritoneal macrophages. Its acute toxicity (LD50 > 200 mg/kg in CD1 mice) was similar to that in the literature for the least toxic lipid formulations of amphotericin B. The relative liver weight increased slightly in mice treated daily with a dose of 20 mg/kg LC-AmB, as did the kidney weight in this group and the group treated with Fungizone. There was also a dose-dependent decrease in the haematocrit with all formulations. All treatments caused significant increases in transaminase levels. Total hepatic CYP 450 was slightly but not significantly increased in the groups treated with 20 mg/kg LC-AmB, Abelcet and Fungizone. However, expression of some isoforms of CYP 450 was reduced, the most marked being the hepatic CYP 3A1 after treatment with 20 mg/kg LC-AmB, Abelcet and Fungizone. The effects on hepatic function are probably related to accumulation in organs rich in phagocytic cells. CONCLUSION: LC-AmB did not induce any new toxicity compared with Abelcet and Fungizone.
Amphotericin B↗
Polymeric carriers for amphotericin B: in vitro activity, toxicity and therapeutic efficacy against systemic candidiasis in neutropenic mice.
OBJECTIVE: To study the toxicity and activity of two new amphotericin B formulations: poly(epsilon-caprolactone) nanospheres coated with poloxamer 188 (AmB-NP) and mixed micelles with the same surfactant (AmB-MM). MATERIALS AND METHODS: The toxicity of these formulations was evaluated in erythrocytes, J774.2 macrophages and LLCPK1 renal cells, as well as in mice. Activity was determined in clinical isolates and in neutropenic mice. Mice were made neutropenic with 5-fluorouracil, infected with Candida albicans and treated with the antifungal formulations for three consecutive days. AmB association in cells and accumulation in kidneys and liver of animals was quantified by HPLC. RESULTS: Both formulations decreased between 8- and 10-fold the MIC of the polyene against clinical isolates of C. albicans. However, their activity was lower than or equal to that of AmB-deoxycholate when it was assessed against C. albicans-infected macrophages. When given as a single intravenous dose in mice, AmB-MM and AmB-NP had an LD50 of 9.8 and 18.6 mg/kg, respectively, compared with 4 mg/kg for AmB-deoxycholate. Comparison of residual infection burdens in the liver and kidneys showed that AmB-deoxycholate (0.5 mg/kg) was more effective and faster in eradicating yeast cells than polymeric formulations. This fact can be related to a lower AmB accumulation inside macrophages and in liver and kidneys (about 1.5 mg drug/g tissue) of mice, compared with those detected for AmB-deoxycholate (4 mg drug/g). Overall, the efficacy of these formulations at 2 mg/kg was equal to that of AmB-deoxycholate at 0.5 mg/kg. CONCLUSIONS: AmB-MM and AmB-NP decreased the in vivo antifungal activity of AmB, and higher concentrations were therefore necessary to obtain a similar therapeutic effect. However, these higher concentrations were achievable owing to the reduced toxicity of these formulations.
Amphotericin B↗
A420983, a novel, small molecule inhibitor of LCK prevents allograft rejection.
Explore the source record for details and available documents.
Animals↗
Requirement of the JIP1 scaffold protein for stress-induced JNK activation.
The c-Jun N-terminal kinase (JNK) signal transduction pathway is activated in response to the exposure of cells to environmental stress. Components of the JNK signaling pathway interact with the JIP1 scaffold protein. JIP1 is located in the neurites of primary hippocampal neurons. However, in response to stress, JIP1 accumulates in the soma together with activated JNK and phosphorylated c-Jun. Disruption of the Jip1 gene in mice by homologous recombination prevented JNK activation caused by exposure to excitotoxic stress and anoxic stress in vivo and in vitro. These data show that the JIP1 scaffold protein is a critical component of a MAP-kinase signal transduction pathway.
Adaptor Proteins, Signal Transducing↗
Tamoxifen encapsulation within polyethylene glycol-coated nanospheres. A new antiestrogen formulation.
When dealing with solid tumors in vivo, pegylated long-circulating carrier systems show, after intravenous administration, an attractive extravasation profile with an enhanced localization in the tumoral interstitium. These systems could be of help for the delivery of cancer fighting drugs, such as Tamoxifen, a well known antiestrogen used in breast cancer therapy that possesses an extended biodistribution in vivo. This work aimed at encapsulating Tamoxifen in long-circulating poly(MePEGcyanoacrylate-co-hexadecylcyanoacrylate) 1:4 nanospheres. Tamoxifen-loaded poly(MePEGcyanoacrylate-co-hexadecylcyanoacrylate) nanospheres were successfully synthesized and characterized in terms of hydrophilicity/hydrophobicity by a model made up from near infrared spectra using principal component analysis. Zeta potential, drug loading, encapsulation efficiency, as well as biological effect, in vitro release and nanospheres integrity were also investigated. Even though near infrared spectroscopy could not detect Tamoxifen, it revealed that Pluronic F68 was associated with the pegylated nanospheres. HPLC measurements demonstrated that Tamoxifen was encapsulated in the pegylated nanospheres following a partition equilibrium between the polymeric and the aqueous phases. The Tamoxifen encapsulated in the nanospheres still showed a transcription inhibitory activity in ex vivo experiments. However, zeta potential and in vitro release suggested that Tamoxifen was essentially localized at the nanoparticles surface, resulting in an important and immediate drug release.
Drug Delivery Systems↗
Reduction of no synthase expression and tumor necrosis factor alpha production in macrophages by amphotericin B lipid carriers.
The present study compared the abilities of different lipid carriers of amphotericin B (AMB) to activate murine peritoneal macrophages, as assessed by their capacities to produce nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha). Although AMB alone did not induce NO production, synergy was observed with gamma interferon but not with lipopolysaccharide. This synergy could not be explained by the mobilization of the nuclear activation factor NF-kappaB by AMB. On the other hand, AMB induced TNF-alpha production without a costimulator and no synergy was observed. Anti-TNF-alpha antibodies did not influence NO production, and an inhibitor of NO synthase did not affect TNF-alpha production, indicating that the production of one of these effector molecules was independent of that of the other. The incorporation of AMB into lipid carriers reduced NO and TNF-alpha production with all formulations but more so with liposomes than with lipid complexes. NO production was correlated with the induction of NO synthase II, revealed by Western blotting. The extent of association of AMB with macrophages depended on the formulation, especially on the AMB/lipids ratio: the higher the ratio was, the greater the AMB association with macrophages. However, there was no clear correlation between AMB association with macrophages, whether internalized or bound to the membrane, and immunostimulating effects. These results may explain the reduced toxicities of lipid-based formulations of AMB.
Adjuvants, Immunologic↗
Chk2/hCds1 functions as a DNA damage checkpoint in G(1) by stabilizing p53.
Chk2/hcds1, the human homolog of the Saccharomyces cerevisiae RAD53/SPK1 and Schizosaccharomyces pombe cds1 DNA damage checkpoint genes, encodes a protein kinase that is post-translationally modified after DNA damage. Like its yeast homologs, the Chk2/hCds1 protein phosphorylates Cdc25C in vitro, suggesting that it arrests cells in G(2) in response to DNA damage. We expressed Chk2/hCds1 in human cells and analyzed their cell cycle profile. Wild-type, but not catalytically inactive, Chk2/hCds1 led to G(1) arrest after DNA damage. The arrest was inhibited by cotransfection of a dominant-negative p53 mutant, indicating that Chk2/hCds1 acted upstream of p53. In vitro, Chk2/hCds1 phosphorylated p53 on Ser-20 and dissociated preformed complexes of p53 with Mdm2, a protein that targets p53 for degradation. In vivo, ectopic expression of wild-type Chk2/hCds1 led to increased p53 stabilization after DNA damage, whereas expression of a dominant-negative Chk2/hCds1 mutant abrogated both phosphorylation of p53 on Ser-20 and p53 stabilization. Thus, in response to DNA damage, Chk2/hCds1 stabilizes the p53 tumor suppressor protein leading to cell cycle arrest in G(1).
Checkpoint Kinase 2↗
Reduction of the uptake by a macrophagic cell line of nanoparticles bearing heparin or dextran covalently bound to poly(methyl methacrylate).
Amphiphilic and fluorescent covalently labelled core-shell nanoparticles based on poly(methyl methacrylate) (PMMA), were prepared by random copolymerisation of N-Vinyl carbazole (NVC) with MMA, initiated on polysaccharidic radicals, yielding diblock copolymers of either dextran-P(MMA-NVC) (Nanodex* particles), or heparin-P(MMA-NVC) (Nanohep* particles). Nanoparticles made from random copolymers of P(MMA-NVC) (PMMA*) were used as controls. The interactions between particles and a J774A1 murine macrophage-like cell line were quantified by direct measurement of the cell-associated fluorescence. The association with the cells occurred within 30 min. Nanodex* and Nanohep* showed considerably less association than the control PMMA* particles. Some of the particle uptake could be attributed to phagocytosis, but more than 50% of the cell-associated fluorescence persisted at low temperature or in the presence of cytochalasin B. The results suggest that both the adsorption and the internalisation processes can be inhibited by the presence of the polysaccharide chains. In conclusion, these results confirm that nanoparticles prepared with heparin or dextran chains on their surface, probably in a brush-like configuration, show "stealth" properties in vitro as had previously been observed in vivo. If this biomimetic approach can also be applied to biodegradable polymers, these systems would provide at least an alternative to PEG-modified particles as long-circulating drug carriers systems or imaging agents.
Animals↗
Stealth PEGylated polycyanoacrylate nanoparticles for intravenous administration and splenic targeting.
The aim of the present work was to investigate the biodistribution characteristics of PEG-coated polycyanoacrylate nanoparticles prepared by the nanoprecipitation/solvent diffusion method using the previously synthesized poly(MePEGcyanoacrylate-hexadecylcyanoacrylate) copolymer. It was observed that [14C]-radiolabeled PEGylated nanoparticles remained for a longer time in the blood circulation after intravenous administration to mice, compared to the non-PEGylated poly(hexadecylcyanoacrylate) (PHDCA) nanoparticles. Furthermore, hepatic accumulation was dramatically reduced, whereas a highly increased spleen uptake was shown. The PEGylation degree of the polymer seemed not to affect the in vivo behavior of the nanoparticles, whereas previously obtained in vitro data have shown a modification of plasma protein adsorption depending on the density of PEG at the surface of the particles. Moreover, the study of the in vitro cytotoxicity of the nanoparticles revealed that the PEGylation of the cyanoacrylate polymer reduced its toxicity. These results open up interesting perspectives for the targeting of drugs to other tissues than the liver.
Animals↗
Ability of doxorubicin-loaded nanoparticles to overcome multidrug resistance of tumor cells after their capture by macrophages.
PURPOSE: Investigation of the ability of doxorubicin-loaded nanoparticles (NP/Dox) to overcome multidrug resistance (MDR) when they have first been taken up by macrophages. METHODS: The growth inhibition of P388 sensitive (P388) and resistant (P388/ADR) tumor cells was evaluated in a coculture system consisting of wells with two compartments. The tumor cells were seeded into the lower compartment, the macrophages were introduced into the upper part in which the drug preparations were also added. RESULTS: Doxorubicin exerted lower cytotoxicity on tumor cells in coculture compared with direct contact. In P388/ADR, NP/Dox cytotoxicity was far higher than that of free doxorubicin (Dox). Three different formulations of cyclosporin A (either free (CyA), loaded to nanoparticles (NP/CyA) or in a combined formulation with doxorubicin (NP/Dox-CyA)), were added to modulate doxorubicin efficacy. The addition of cyclosporin A to Dox increased drug cytotoxicity. Both CyA added to NP/Dox and NP/Dox-CyA were able to bypass drug resistance. CONCLUSIONS: Despite the barrier role of macrophages, NP/Dox remained far more cytotoxic than Dox against P388/ADR. Both NP/Dox + CyA and NP/Dox-CyA allowed to overcome MDR, but the last one should present greater advantage in vivo by confining both drugs in the same compartment, hence reducing the adverse effects.
Animals↗
Interactions between a macrophage cell line (J774A1) and surface-modified poly (D,L-lactide) nanocapsules bearing poly(ethylene glycol).
The interactions of naked and surface-modified poly(D,L-lactic acid) (PLA) nanocapsules (NC), where polyethyleneglycol (PEG) was adsorbed or covalently attached, have been studied with a macrophage-like cell line. The fluorescent oil marker, DiD, was successfully encapsulated in NCs in order to follow their interactions with cells. The cell-associated fluorescence obtained with PEG-PLA NC was about 3- to 13-fold lower than that obtained with naked-PLA NC. The effects of PEG chain length, its content as a percentage of total polymer and NC concentration in the culture medium were evaluated. PEG-PLA NC showed dramatically reduced fluorescence association with cells during an 18 h incubation compared with naked-PLA NC, showing that covalent attachment of PEG is important for the persistence of low uptake. The best results in reducing cell-associated fluorescence were obtained with a surface-modified PEG-PLA NC bearing a chain with 20000 MW. Increasing the percentage of PEG produced a reduction in marker association for a given PEG chain length. Moreover, when the PEG-containing poloxamer was simply adsorbed, marker association was dependent on the extent of dilution and the type of serum in the culture medium. Serum proteins, especially immunoglobulins, increased cell-associated fluorescence for PEG-adsorbed NC, but had very little effect on PEG-PLA NC. Marker association was only partially inhibited in the presence of cytochalasin B. The mechanisms of cell-NC interaction depended on the characteristics of the NC surface in each formulation. When the NC was physically separated from cells no diffusion of fluorescent marker in aqueous medium occurred. Nevertheless, collision-mediated transfer of DiD from NC to J774 cells was a non-negligible route of marker transfer, mainly for naked NC. However, this collision-mediated transfer was reduced for the PEG-PLA NC probably due to the restricted contact between NC and cells afforded by PEG steric hindrance at the surface.
Animals↗
Production of ex vivo expanded hematopoietic cells and progenitors in a closed bioreactor, starting with a small volume marrow collection: A feasibility study in patients with poor-risk breast cancer and receiving high-doses of cyclophosphamide.
We report a clinical pilot study conducted in 6 women with poor-prognosis breast cancer. The goal was to evaluate the feasibility and safety of producing hematopoietic progenitors and cells from a small marrow sample, for clinical use after high-dose cyclophosphamide. A small volume marrow collection was obtained, using local anesthesia and conscious sedation, before the first of two chemotherapy cycles. Cells were cryopreserved, and later thawed to inoculate two Aastrom Biosciences Inc Replicell bioreactors, on time to reinfuse ex vivo expanded cells after the second chemotherapy cycle. Patients recovered neutrophils and platelets at similar times after the first and second chemotherapy cycles, and showed comparable clinical events. This pilot study prepares future randomized trials, designed to evaluate clinical benefits associated with the use of ex vivo expanded cells in the setting of multicycle high-dose chemotherapy.
Aged↗
A nonsense mutation (R242X) in the branched-chain alpha-keto acid dehydrogenase E1alpha subunit gene (BCKDHA) as a cause of maple syrup urine disease. Mutations in brief no. 160. Online.
Mutation analysis of DNA from cultured amniocytes with absent branched-chain alpha-ketoacid dehydrogenase activity revealed a C to T transition producing a nonsense mutation (R242X) in exon 7 of the gene encoding the E1a subunit of this multienzme complex (BCKDHA). This pregnancy occured in a large consanguinous pedigree with mutiple individuals with maple syrup urine disease (MSUD). PCR amplification of the region surrounding exon 7 allowed the identification of this mutation as well as two other previously identified mutations which cause MSUD.
3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
Modulation of nitric oxide production in RAW 264.7 cells by transforming growth factor-beta and interleukin-10: differential effects on free and encapsulated immunomodulator.
The mouse macrophage cell line RAW 264.7 can be stimulated to produce nitric oxide (NO) by muramyltripeptide cholesterol included within biodegradable poly(D,L-lactide) nanocapsules (NC MTPChol). The aim of this work was to determine whether one or both of the cytokines transforming growth factor-beta (TGF-beta) and interleukin-10 (IL-10) could be responsible for feedback control seen at high concentrations. Activated RAW 264.7 cells produced TGFbeta1. When exogenous TGF-beta1 was added during stimulation, a dose-dependent inhibition of NO production was observed when NC MTP-Chol was used, whereas activation by the soluble muramyl dipeptide (MDP) was not affected. Furthermore, addition of a blocking antibody to TGF-beta arrested the fall in NO production seen at high concentrations of NC MTP-Chol. Addition of IL-10 during RAW 264.7 cell activation also reduced NO production; however, in this case, both NC MTP-Chol and MDP were equally affected. The presence of anti-IL-10 antibody during activation significantly increased NO production.
Acetylmuramyl-Alanyl-Isoglutamine↗
Reversion of multidrug resistance with polyalkylcyanoacrylate nanoparticles: towards a mechanism of action.
Polyalkylcyanoacrylate (PACA) nanoparticles loaded with doxorubicin allowed multidrug resistance to be overcome in vitro. However, increased cytotoxicity is not always correlated with an increased level of intracellular drug. Although we have previously shown that PACA nanoparticles are not endocytosed by tumour cells, we report here that a direct interaction between nanoparticles and cells is a necessary requirement for overcoming resistance. In addition, the results showed that the degradation products of PACA (mainly polycyanoacrylic acid) in the presence of doxorubicin are able to increase both accumulation and cytotoxicity, thus suggesting the formation of a doxorubicin-polycyanoacrylic acid ion pair. It is therefore concluded that resistance is overcome as a result of both the adsorption of nanoparticles to the cell surface and increased doxorubicin diffusion by the accumulation of an ion pair at the plasma membrane.
Animals↗
In-vitro and in-vivo evaluation of a new amphotericin B emulsion-based delivery system.
The in-vitro and in-vivo toxicity and activity of a new emulsion-based delivery system for amphotericin B (AmB-E) and of deoxycholate-amphotericin B (Fungizone) were studied. In vitro, Candida albicans and human red blood cells (RBCs) were treated with either product and dose-response curves for various cellular effects (changes in potassium cell content, haemoglobin leakage from RBCs and colony-forming ability of fungal cells) were obtained. AmB-E was less toxic than Fungizone against human RBCs and equally active against C. albicans cells. In-vivo studies showed that the LD50 of AmB-E and Fungizone in noninfected OF1 mice were 7.24 and 3.46 mg/kg, respectively. The therapeutic efficacy of AmB-E was assessed in murine candidiasis. Firstly, the efficacy of equal doses (0.8 mg/kg) of AmB-E and Fungizone was evaluated in infected mice. Both formulations increased the survival time compared to the control and were equally effective in reducing the cfu counts in the kidney. In the same model of infection, the maximum tolerated doses (MTD) of Fungizone and AmB-E were determined in order to study the efficacies of Fungizone and AmB-E at their respective MTD. AmB-E significantly increased the number of long-term survivors compared with Fungizone (MTD:2 and 1 mg/kg, respectively). Thus, AmB-E was more effective than Fungizone for treatment of systemic mycoses at the MTD.
Amphotericin B↗
Early assessment of outcome by ST-segment analysis after thrombolytic therapy in acute myocardial infarction.
As an early marker of outcome, the sum of ST-segment elevation resolution between the electrocardiogram before and 3 hours after initiation of thrombolysis was investigated in 77 patients with acute myocardial infarction. Prospectively, three groups were defined according to complete (> or = 70%, n = 34), partial (< 70% to > or = 30%, n = 26), or no (< 30%, n = 17) ST resolution. There were considerable differences in the enzyme-determined infarct size (alpha-hydroxybutyrate dehydrogenase release for complete, partial, and no ST resolution: 529 +/- 397 IU/L, 689 +/- 484 IU/L, and 1293 +/- 742 IU/L, respectively; p = 0.0001) and the angiographic left ventricular function 1 week later (ejection fraction 58% +/- 10%, 53% +/- 13%, and 43% +/- 12%, respectively, p < 0.01; regional dyssynergic area 24 +/- 19, 39 +/- 23, and 50 +/- 21 U2, respectively, p < 0.01). Early reperfusion as assessed by creatine kinase release measured in 15-minute intervals was 90%, 65%, and 18%, respectively (p = 0.0001). Differences in degrees of ST-elevation resolution at 3 hours may help facilitate timely screening of patients for appropriate therapeutic intervention. Patients with complete ST resolution may be considered for early discharge, and patients with no ST resolution may be candidates for an early invasive approach or additional thrombolytic therapy.
Cardiac Catheterization↗