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The influence of alkaline and the neutral grade of magnesium aluminometasilicate as a porous solid carrier for the liquid self-emulsifying formulation with ibuprofen is investigated. Ibuprofen is dissolved in Labrasol, then this solution is adsorbed on the silicates. The drug to the silicate ratio is 1:2, 1:4, and 1:6, respectively. The properties of formulations obtained are analyzed, using morphological, porosity, crystallinity, and dissolution studies. Three solid self-emulsifying (S-SE) formulations containing Neusilin SG2 and six consisting of Neusilin US2 are in the form of powder without agglomerates. The nitrogen adsorption method shows that the solid carriers are mesoporous but they differ in a specific surface area, pore area, and the volume of pores. The adsorption of liquid SE formulation on solid silicate particles results in a decrease in their porosity. If the neutral grade of magnesium aluminometasilicate is used, the smallest pores, below 10 nm, are completely filled with liquid formulation, but there is still a certain number of pores of 40–100 nm. Dissolution studies of liquid SEDDS carried out in pH = 1.2 show that Labrasol improves the dissolution of ibuprofen as compared to the pure drug. Ibuprofen dissolution from liquid SE formulations examined in pH of 7.2 is immediate. The adsorption of the liquid onto the particles of the silicate causes a decrease in the amount of the drug released. Finally, more ibuprofen is dissolved from S-SE that consist of the neutral grade of magnesium aluminometasilicate than from the formulations containing the alkaline silicate.KEY WORDS: dissolution, ibuprofen, labrasol, magnesium aluminometasilicate, self-emulsifying powder 相似文献
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Dr. Benedykt Fuliński 《Development genes and evolution》1922,51(1):575-586
Ohne Zusammenfassung
Mit 2 Textabbildungen. 相似文献
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Proteases, also referred to as peptidases, are the enzymes that catalyse the hydrolysis of peptide bonds in polipeptides.
A variety of biological functions and processes depend on their activity. Regardless of the organism’s complexity, peptidases
are essential at every stage of life of every individual cell, since all protein molecules produced must be proteolytically
processed and eventually recycled. Protease inhibitors play a crucial role in the required strict and multilevel control of
the activity of proteases involved in processes conditioning both the physiological and pathophysiological functioning of
an organism, as well as in host-pathogen interactions. This review describes the regulation of activity of bacterial proteases
produced by dangerous human pathogens, focusing on the Staphylococcus genus. 相似文献
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Artur J Sabat Benedykt Wladyka Klaudia Kosowska-Shick Hajo Grundmann Jan Maarten van Dijl Julia Kowal Peter C Appelbaum Adam Dubin Waleria Hryniewicz 《BMC microbiology》2008,8(1):129
Background
Staphylococcus aureus expresses several proteases, which are thought to contribute to the virulence of this bacterium. Here we focus on aureolysin, the major thermolysin-like metalloprotease. Despite the importance of aureolysin in the physiology and pathogenesis of S. aureus, relatively little information was so far available concerning the aur gene diversity and mobility within and between the major subdivisions of the S. aureus population. Therefore, an epidemiologically and genetically diverse collection of S. aureus strains was used to determine the range of aureolysin (aur) gene polymorphism. 相似文献7.
Staphylococcal cysteine proteases are implicated as virulence factors in human and avian infections. Human strains of Staphylococcus aureus secrete two cysteine proteases (staphopains A and B), whereas avian strains express staphopain C (ScpA2), which is distinct from both human homologues. Here, we describe probable reasons why the horizontal transfer of a plasmid encoding staphopain C between avian and human strains has never been observed. The human plasma serine protease inhibitor α1-antichymotrypsin (ACHT) inhibits ScpA2. Together with the lack of ScpA2 inhibition by chicken plasma, these data may explain the exclusively avian occurrence of ScpA2. We also clarify the mechanistic details of this unusual cross-class inhibition. Analysis of mutated ACHT variants revealed that the cleavage of the Leu383-Ser384 peptide bond results in ScpA2 inhibition, whereas hydrolysis of the preceding peptide bond leads to ACHT inactivation. This evidence is consistent with the suicide-substrate-like mechanism of inhibition. 相似文献
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Natalia Stach Magdalena Kalinska Michal Zdzalik Radoslaw Kitel Abdulkarim Karim Karol Serwin Wioletta Rut Katrine Larsen Abeer Jabaiah Magdalena Firlej Benedykt Wladyka Patrick Daugherty Henning Stennicke Marcin Drag Jan Potempa Grzegorz Dubin 《Structure (London, England : 1993)》2018,26(4):572-579.e4
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Kalińska M Kantyka T Greenbaum DC Larsen KS Władyka B Jabaiah A Bogyo M Daugherty PS Wysocka M Jaros M Lesner A Rolka K Schaschke N Stennicke H Dubin A Potempa J Dubin G 《Biochimie》2012,94(2):318-327
Human strains of Staphylococcus aureus secrete two papain-like proteases, staphopain A and B. Avian strains produce another homologous enzyme, staphopain C. Animal studies suggest that staphopains B and C contribute to bacterial virulence, in contrast to staphopain A, which seems to have a virulence unrelated function. Here we present a detailed study of substrate preferences of all three proteases. The specificity of staphopain A, B and C substrate-binding subsites was mapped using different synthetic substrate libraries, inhibitor libraries and a protein substrate combinatorial library. The analysis demonstrated that the most efficiently hydrolyzed sites, using Schechter and Berger nomenclature, comprise a P2–Gly↓Ala(Ser) sequence motif, where P2 distinguishes the specificity of staphopain A (Leu) from that of both staphopains B and C (Phe/Tyr). However, we show that at the same time the overall specificity of staphopains is relaxed, insofar as multiple substrates that diverge from the sequences described above are also efficiently hydrolyzed. 相似文献