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- Barauskas, Justas, et al.
(författare)
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Synthesis and aqueous phase behavior of 1-glyceryl monooleyl ether
- 2005
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 1873-4367 .- 0927-7765. ; 41:1, s. 49-53
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of 1-glyceryl monooleyl ether (GME) has been accomplished yielding material of high purity (99.6%). The aqueous phase behavior of synthesized lipid has been investigated by using polarized microscopy and small angle X-ray diffraction. As a result, a partial temperature-composition phase diagram has been constructed. GME forms a reversed micellar solution and reversed hexagonal liquid crystalline phase at low and high hydration, respectively. The hexagonal phase coexists with excess water and is stable up to about 63 degreesC. These findings make GME an interesting alternative to glycerol monoesters in various fields of applications. (C) 2004 Elsevier B.V. All rights reserved.
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| 4. |
- Barauskas, Justas, et al.
(författare)
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Towards redox active liquid crystalline phases of lipids: a monoolein/water system with entrapped derivatives of ferrocene
- 2003
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Ingår i: Chemistry and Physics of Lipids. - 0009-3084. ; 123:1, s. 87-97
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Tidskriftsartikel (refereegranskat)abstract
- The phase and electrochemical behavior of the aqueous mixtures of monoolein (MO) and synthetic ferrocene (Fc) derivatives containing long alkyl chains -(Z)-octadec-9-enoylferrocene (1), (Z)-octadecen-9-ylferrocene (2), and ferrocenylmethyl (Z)-octadec-9-enoate (3)-were studied. At low hydration, the reversed micelles (L-2 phase) and cubic Q(230) phase of MO can accommodate relatively high amounts ( > 6 wt.%) of the Fc-derivative 2, whereas at high hydration, the pseudoternary cubic phase Q(224) is destabilized even at about 2 wt.% of this Fc. Increasing the Fc-derivative content induces L-alpha L-2 and L-alpha --> reversed bicontinuous cubic phase (Q(II)) H-II transitions depending upon hydration. A rough study of the MO system containing compounds I and 3 indicates very similar phase behavior to that of the MO/2/H2O system. Compound 2 apparently has no effect on the lipid monolayer thickness in the pseudoternary L-alpha, H-II and Q(II) liquid crystalline phases of MO. Within a 3D-structure of the Q224 phase, derivatives 1-3 exhibit electrochemical activity on the gold electrode. The one-electron redox conversion processes are electro-chemically quasi-reversible and controlled by diffusion. The values of apparent diffusion coefficient (D-app) and heterogeneous electron-transfer rate constant (k(s)) of Fcs are significantly lo er in the cubic,phase matrix when compared to the acetonitrile solution. By contrast, the MO H-II phase with entrapped Fc-derivatives does not exhibit electrochemical activity on the electrode surface. It is suggested that the diffusional anisotropy and/or localized aggregation of compounds 1-3 within a 2D-structure of the H-II phase account(s) for the latter observation. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.
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| 5. |
- Frisch, M, et al.
(författare)
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Cultural bias in the AAP's 2012 Technical Report and Policy Statement on male circumcision
- 2013
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Ingår i: Pediatrics. - : American Academy of Pediatrics (AAP). - 1098-4275 .- 0031-4005. ; 131:4, s. 796-800
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Tidskriftsartikel (refereegranskat)abstract
- The American Academy of Pediatrics recently released its new Technical Report and Policy Statement on male circumcision, concluding that current evidence indicates that the health benefits of newborn male circumcision outweigh the risks. The technical report is based on the scrutiny of a large number of complex scientific articles. Therefore, while striving for objectivity, the conclusions drawn by the 8 task force members reflect what these individual physicians perceived as trustworthy evidence. Seen from the outside, cultural bias reflecting the normality of nontherapeutic male circumcision in the United States seems obvious, and the report’s conclusions are different from those reached by physicians in other parts of the Western world, including Europe, Canada, and Australia. In this commentary, a different view is presented by non–US-based physicians and representatives of general medical associations and societies for pediatrics, pediatric surgery, and pediatric urology in Northern Europe. To these authors, only 1 of the arguments put forward by the American Academy of Pediatrics has some theoretical relevance in relation to infant male circumcision; namely, the possible protection against urinary tract infections in infant boys, which can easily be treated with antibiotics without tissue loss. The other claimed health benefits, including protection against HIV/AIDS, genital herpes, genital warts, and penile cancer, are questionable, weak, and likely to have little public health relevance in a Western context, and they do not represent compelling reasons for surgery before boys are old enough to decide for themselves.
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| 6. |
- Talaikyte, Z, et al.
(författare)
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Interactions of cyclic AMP and its dibutyryl analogue with a lipid layer in the aqueous mixtures of monoolein preparation and dioleoyl phosphatidylcholine as probed by X-ray diffraction and Raman spectroscopy
- 2004
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Ingår i: Journal of Biological Physics. - 0092-0606. ; 30:1, s. 83-96
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Tidskriftsartikel (refereegranskat)abstract
- Interactions of adenosine 3':5'-cyclic monophosphate (cAMP) and N-6,2'-O-dibutyryl-adenosine 3':5'-cyclic monophosphate (dbcAMP) with a lipid layer composed of monoolein-based preparation and dioleoyl phosphatidylcholine ( DOPC) were investigated by small-angle X-ray diffraction (SAXD) and Raman spectroscopy. The reversed hexagonal (H-II) MO/DOPC/H2O phase of 65:15:20 wt.% composition was selected as a reference system. SAXD revealed that entrapment (at the expense of water) of 3 wt.% cAMP into the reference system did not change the polymorphic form and structural parameters of the phase. The same content of dbcAMP induced the transition from the HII phase to the reversed bicontinuous cubic phase of space group Ia3d. This transition is explained by the increase of lipid head-group area due to the penetration of the acylated adenine group of dbcAMP into the polar/apolar region of lipid layer. The conclusion is supported by Raman spectroscopy, showing the disruption/weakening of hydrogen bonding in the MO/DOPC-based matrix at the N1- and N3-sites of the dbcAMP adenine ring. As distinct from dbcAMP, cAMP remains mostly in the water channels of the HII phase, although the phosphate residue of nucleotide interacts with the quaternary ammonium group of DOPC. Both nucleotides increase the population of gauche isomers in the DOPC choline group.
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