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  • Cell & Developmental Biology  (5)
  • Polymer and Materials Science  (5)
  • Dihydroartemisinin  (2)
  • cloud point  (2)
  • 1
    ISSN: 1432-1041
    Keywords: Key words Pharmacokinetics ; Bioequivalence ; Mefloquine ; Uncomplicated falciparum malaria ; Dihydroartemisinin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: To assess the pharmacokinetics and relative bioavailability/bioequivalence of three commercial tablet formulations of mefloquine, i.e. Lariam (reference formulation), Mephaquin 100 Lactab and Eloquin-250, when given sequentially after dihydroartemisinin in Thai patients with acute uncomplicated falciparum malaria. Methods: Twenty-nine Thai patients with acute uncomplicated falciparum malaria were randomised to receive an initial dose of 300 mg dihydroartemisinin, followed by 1250 mg mefloquine (at 24 h and 30 h after dihydroartemisinin) given as either Lariam (n=10 cases), Mephaquin (n=9 cases) or Eloquin-250 (n=10 cases). Serial blood samples were obtained up to day 42 after treatment with mefloquine. Mefloquine concentrations were determined in whole blood by means of ultraviolet high-performance liquid chromatography. The pharmacokinetic parameters of mefloquine were estimated using non-compartmental and compartmental analysis. Results: The three combination regimens were well tolerated. Patients in all treatment groups had a rapid initial response. However, nine patients (four and five cases in regimen containing Mephaquin 100 Lactab and Eloquin-250, respectively) had reappearance of parasitaemia during the follow-up period. Mefloquine from the three formulations showed significantly different pharmacokinetic and bioavailability metrics. Significantly lower peak plasma concentrations (Cmax) and areas under the plasma concentration–time curve (AUC; AUC0–48h, AUC0–7days, and total AUC) were observed with Mephaquin 100 Lactab than with the other two formulations. Mean values for relative bioavailability of the test to standard products were 49.1% (Mephaquin 100 Lactab) and 72.4% (Eloquine-250). Based on the criteria set, the bioavailability of the two test products (Mephaquin 100 Lactab and Eloquine-250) was considered non-equivalent to the reference product with respect to the rate (tmax, Cmax) and extent (AUC0–48h, AUC0–7days, total AUC) of mefloquine absorption.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 53 (1998), S. 375-376 
    ISSN: 1432-1041
    Keywords: Key words Artesunate ; Dihydroartemisinin ; Pharmacokinetics ; Bioequivalence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-904X
    Keywords: nanocrystals ; submicron crystals ; suspensions ; steam sterilization ; physical stability ; surfactants ; cloud point ; ethyl diatrizoate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study the effects of formulation variables on the physical stability of a submicron crystal (nanocrystal) suspension under steam sterilization conditions. Methods. Suspensions of ethyl diatrizoate nanocrystals were prepared by wet milling in the presence of the surfactant poloxamine 908. Particle size distribution and zeta potential were measured by photon correlation spectroscopy. Results. On heating, the mean particle size of the nanocrystal suspension remained essentially unchanged up to 110°C, the cloud point of the stabilizing surfactant, but increased significantly above that temperature. The increase in particle size was a result of particle aggregation rather than crystal growth. Adding a cloud point booster to the suspension significantly minimized the particle aggregation at high temperatures. The purity of poloxamine 908 and the tonicity agent and buffer salt used also affected the heat stability of the suspension, the latter agents apparently through altering the surfactant cloud point. Conclusions. The aggregation of the ethyl diatrizoate nanocrystalline suspension under steam sterilization conditions was a result of phase separation of the stabilizing surfactant at its cloud point. When formulated with a cloud point booster to prevent the phase-separation, the suspension maintained its physical stability under steam sterilization without any significant change in particle size distribution.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-904X
    Keywords: nonionic surfactants ; cloud point ; cloud point boosters ; poloxamers ; poloxamines ; liquid formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To determine the cloud point of a variety of nonionic surfactants and to search for means to raise the surfactant cloud point in liquid formulations. Methods. Cloud points of nonionic surfactants were determined visually in a water bath. Organic compounds, many of which have been used as pharmaceutical excipients, were tested initially for effect on the cloud point of poloxamine 908. Four effective cloud point boosters (CPBs) from different structural classes were further tested on additional surfactants. Results. A number of compounds can raise the cloud point of nonionic surfactants. These cloud point boosters are classified into two categories: nonionic and ionic. The nonionic CPBs include poly(ethylene glycols), propylene glycol, methanol, ethanol, isopropanol, and 2-hydroxypropyl-β-cyclodextrin. They are effective at molar concentrations. The ionic CPBs include anionic and cationic surfactants, charged phospholipids, long chain fatty acids, and bile salts. They are effective at millimolar concentrations. Conclusions. The cloud point of nonionic surfactants used in liquid formulations can be modulated through the proper choice of excipient.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1058-8388
    Keywords: CRABP-I ; P19 cells ; DNA methylation ; Gene expression ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The mouse cellular retinoic acid binding protein-I (CRABP-I) gene is specifically up-regulated by retinoic acid (RA) in P19 mouse embryonal carcinoma cells, and its expression in animals is spatially and temporally restricted to RA-sensitive tissues during embryonic development. This study demonstrates that, in adult mouse tissues and P19 cells where the expression of CRABP-I is detected at the basal level, the 5′- flanking region of the CRABP-I gene is hypermethylated at the C residues of all the Hpa II sites. Conversely, in mouse embryos during early stages of development when the expression of CRABP-I gene is detected at a much higher level, this region is demethylated at these Hpa II sites. In P19, enhancement on the RA-induced up-regulation of CRABP-I can be observed in cells treated with 5-azacytidine (5-AzaC) in conjunction with RA, where partial demethylation in the 5′-flanking region of CRABP-I gene is observed. Nuclear run-on experiments indicate that increased message levels of CRABP-I in P19 cells can be accounted for, at least partially, by increases in its transcription rates. The induction of retinoic acid receptor (RAR) β by RA can also be enhanced by 5-AzaC, but to a much lesser degree. In contrast, all the Hpa II sites in the structural gene portion, at least in the first two exons, are fully demethylated at the C residues. © 1994 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 1741-1750 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The reinforcement of a natural rubber compound by various surface-modified precipitated silicas was compared. Compound physical properties were determined for two silicas differing in surface area and were used as controls to evaluate these silicas after surface modification by using either a bifunctional organosilane coupling agent (γ-mercaptopropyl-trimethoxysilane) or a new surface modification process. This new process is based on the in situ polymerization of organic monomers solubilized inside surfactant bilayers that are adsorbed onto the silica surface to afford silicas modified with styrene-butadiene and styrene-isoprene copolymers. Both surface modification processes afford materials that dramatically increase the compound cure rate, thereby significantly reducing T90 cure times, while also improving tensile properties, tear strength, abrasion resistance, and compression set of the cured compound. The silane-modified silica gives a higher flex-cracking resistance than do the silicas modified by the in situ polymerization of organic monomers, whereas these latter silicas significantly increase rebound resilience and offer greater overall improvements in rubber compound performance. The rubber compound physical properties obtained using the modified, higher surface area Hi-Sil® 255 silica are generally improved relative to those obtained using the modified Hi-Sil® 233 silica. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 38 (1989), S. 2171-2182 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Butyl acrylate was graft copolymerized onto gelatin using ceric ammonium nitrate as redox initiator. A series of grafted products with various gelatin-to-butyl acrylate ratios were prepared. The molecular weight of the grafted side chains and the number of grafting sites were measured. The possible grafting sites on gelatin macromolecules were pointed out through amino acid analysis. The electron micrograph and DSC analysis showed that the grafted chain (PBA) and backbone gelatin were in separated phases. The graft copolymer was used in the receiving layer of the dye transfer blank film, and the photographic, dye transfer printing, and some physicomechanical properties were studied with satisfactory results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 117-122 
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Structures of poly(ether ether ketone ketone)-poly(ether biphenyl ether ketone ketone) copolymers were studied by using small angle X-ray scattering and the one-dimensional electron density correlation function method. The results revealed that structures of the aggregated state of the copolymers depend closely on the biphenyl content (nb). When nb = 0.35, invariant Q, long period L, average thickness of crystal lamellae d̄, electron density difference ηc - ηa and degree of crystallinity Wc, x assume minimum values.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 18 (1997), S. 23-30 
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal structure of poly(aryl ether biphenyl ether ketone ketone) (PEDEKK) was determined to comprise a two-chain orthorhombic unit cell with dimensions a = 0.778 nm, b = 0.606 nm and c = 2.375 nm by using wide-angle X-ray diffraction (WAXD). According to the orthorhombic system, the 12 reflections of this polymer were indexed. The crystallite size increases with increasing the crystallization temperature. The results of the degree of crystallinity (Wc,x) calculated from WAXD were compatible with those from density (Wc,d) and calorimetry (Wc,h) measurements.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 18 (1997), S. 921-925 
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of 2,3-O-carboxymethylcelluloses (CMC's), which are regioselectively substituted at the C-2 and C-3 position, were prepared and their water solubility was examined. It was found that the lower limit for the degree of substitution (DS) value of water-soluble 2,3-O-CMC is about 0.3. This value was almost the same as that of CMC prepared in a slurry of isopropyl alcohol/water with isopropyl chloroacetate and sodium hydroxide, showing that the uniform alkylation is rather important to convert cellulose into water-soluble derivatives.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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