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RK Gherardi JP Farcet A Créange P Claudepierre D Malapert FJ Authier MH Delfau-Larue 《Canadian Metallurgical Quarterly》1998,51(2):384-389
The aim of this study was to describe an high-performance liquid chromatographic assay for the simultaneous determination of two HIV protease inhibitors, saquinavir and ritonavir, in human serum. The method involved extraction of ritonavir and saquinavir from serum with the aid of solid-phase extraction C18 cartridges followed by high-performance liquid chromatography with a C8 column and ultraviolet detection set at a wavelength of 240 nm. The assay was linear and has been validated over the concentrations range of 0.5-32 microg/ml for ritonavir and 0.075-4.8 microg/ml for saquinavir, from 600 microl serum extracted. In future, the assay will be used to support human population pharmacokinetic studies, and therapeutic drug monitoring for ritonavir and saquinavir. 相似文献
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Summary The thermally stimulated depolarization currents(TSDC) from polyurethanes based on 4,4-dibenzyle diisocyanate(DBDI) and both saturated and unsaturated polyesters were studied over the temperature range 240–410 °K. Pour relaxation peaks were observed. The structure of the TSDC thermograms, location and intensity of the constituent peaks depend both on the urethane content and thermal history of the polymerr The morphological structure of the samples was evidenced using electron microscopy method. 相似文献
65.
C Hountondji K Bulygin A Woisard P Tuffery JB Créchet M Pech KH Nierhaus G Karpova S Baouz 《Chembiochem : a European journal of chemical biology》2012,13(12):1791-1797
Previously we have shown that the CCA end of a P‐tRNA can be crosslinked with the RPL36AL protein of the large subunit of mammalian ribosomes; it belongs to the L44e protein family present in all eukaryotic and archaeal ribosomes. Here we confirm and extend this finding and demonstrate that: 1) this crosslink is specific for a tRNA at the P/E hybrid site, as a tRNA in all other tRNA positions of pre‐translocational ribosomes could not be crosslinked with a ribosomal protein, 2) the crosslink was formed most efficiently with C74 and C75 of P/E‐tRNA, but could also connect the ultimate A of this tRNA with Lys53 of protein RPL36AL, 3) this protein contains seven monomethylated residues (three lysyl and three arginyl residues, as well as glutaminyl residue 51), 4) Q51 is part of a conserved GGQ motif in the L44e proteins in eukaryotic 80S ribosomes that is identical to the universally conserved motif of release factors implicated in promoting peptidyl‐tRNA hydrolysis, and 5) the large number of modifications, in which some of the residues were methylated to about 50 %, might indicate that protein RPL36AL is a preferential target for regulation. 相似文献
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Hoffmeister CR Durli TL Schaffazick SR Raffin RP Bender EA Beck RC Pohlmann AR Guterres SS 《Nanoscale research letters》2012,7(1):251
The aim of the present study was to develop a transdermal system for controlled delivery of melatonin combining three strategies: nanoencapsulation of melatonin, drying of melatonin-loaded nanocapsules, and incorporation of nanocapsules in a hydrophilic gel. Nanocapsules were prepared by interfacial deposition of the polymer and were spray-dried using water-soluble excipients. In vitro drug release profiles were evaluated by the dialysis bag method, and skin permeation studies were carried out using Franz cells with porcine skin as the membrane. The use of 10% (w/v) water-soluble excipients (lactose or maltodextrin) as spray-drying adjuvants furnished redispersible powders (redispersibility index approximately 1.0) suitable for incorporation into hydrogels. All formulations showed a better controlled in vitro release of melatonin compared with the melatonin solution. The best controlled release results were achieved with hydrogels prepared with dried nanocapsules (hydrogels > redispersed dried nanocapsules > nanocapsule suspension > melatonin solution). The skin permeation studies demonstrated a significant modulation of the transdermal melatonin permeation for hydrogels prepared with redispersible nanocapsules. In this way, the additive effect of the different approaches used in this study (nanoencapsulation, spray-drying, and preparation of semisolid dosage forms) allows not only the control of melatonin release, but also transdermal permeation. 相似文献
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I Huez L Créancier S Audigier MC Gensac AC Prats H Prats 《Canadian Metallurgical Quarterly》1998,18(11):6178-6190
The mRNA of vascular endothelial growth factor (VEGF), the major angiogenic growth factor, contains an unusually long (1,038 nucleotides) and structured 5' untranslated region (UTR). According to the classical translation initiation model of ribosome scanning, such a 5' UTR is expected to be a strong translation inhibitor. In vitro and bicistronic strategies were used to show that the VEGF mRNA translation was cap independent and occurred by an internal ribosome entry process. For the first time, we demonstrate that two independent internal ribosome entry sites (IRESs) are present in this 5' UTR. IRES A is located within the 300 nucleotides upstream from the AUG start codon. RNA secondary structure prediction and site-directed mutagenesis allowed the identification of a 49-nucleotide structural domain (D4) essential to IRES A activity. UV cross-linking experiments revealed that IRES A activity was correlated with binding of a 100-kDa protein to the D4 domain. IRES B is located in the first half of the 5' UTR. An element between nucleotides 379 and 483 is required for its activity. Immunoprecipitation experiments demonstrated that a main IRES B-bound protein was the polypyrimidine tract binding protein (PTB), a well-known regulator of picornavirus IRESs. However, we showed that binding of the PTB on IRES B does not seem to be correlated with its activity. Evidence is provided of an original cumulative effect of two IRESs, probably controlled by different factors, to promote an efficient initiation of translation at the same AUG codon. 相似文献
70.
K M?der Y Crémmilleux AJ Domb JF Dunn HM Swartz 《Canadian Metallurgical Quarterly》1997,14(6):820-826
PURPOSE: The purpose of this study was to compare drug release and polymer erosion from biodegradable P(FAD-SA) polyanhydrides in vitro and in vivo in real time and with minimal disturbance of the investigated system. METHODS: P(FAD-SA) 20:80 and P(FAD-SA) 50:50 polymer tablets were loaded with the spin probe 3-carboxy-2,2,5,5-tetramethyl-pyrrollidine-1-oxyl (PCA) and implanted subcutaneously in the neck of rats or placed in 0.1 M phosphate buffer. 1.1 GHz EPR spectroscopy experiments and 7T MRI studies (T1 and T2 weighted) were performed. RESULTS: A front of water penetration was visible by MRI in vitro in the case of P(FAD-SA) 20:80, but not for P(FAD-SA) 50:50. For both polymers, the thickness of the tablets decreased with time and a insoluble, easy deformable residue remained. Important processes such as edema, deformation of the implant, encapsulation and bioresorption were observable by MRI in vivo. P(FAD-SA) 50:50 was almost entirely absorbed by day 44, whereas an encapsulated residue was found for P(FAD-SA) 20:80 after 65 days. The EPR studies gave direct evidence of a water penetration induced changes of the microenvironment inside the tablet. EPR signals were still detectable in P(FAD-SA) 20:80 implants after 65 days, while the nitroxide was released in vitro within 16 days. CONCLUSIONS: Important parameters and processes such as edema, deformation of the tablet, microviscosity inside the tablet and encapsulation can be monitored in real time by the combined use of the noninvasive techniques MRI and EPR leading to better understanding of the differences between the in vitro and in vivo situation. 相似文献