Colloidal structures in media simulating intestinal fed state conditions with and without lipolysis products

Purpose. To study the ultrastructure of biorelevant media and digestion products of self-nanoemulsifying drug delivery system (SNEDDS) at high level BS/PL conditions. Methods. Cryogenic transmission electron microscopy (Cryo-TEM) was employed to visualize the colloid structures in the biorelevant media and lipolytic products generated during hydrolysis of a SNEDDS formulation. Their electrical properties were investigated by measuring their zeta-potential values. Results. In the biorelevant media, vesicles (either unilamellar or multilamellar) and bilayer fragments are visualized. Occasionally, vesicles with an internal deformed structure are recognized, suggesting surface tension or uneven lateral stress. Visualization studies of the intermediate colloidal phases produced during digestion of a SNEDDS using the in vitro lipolysis model revealed the formation of similar structures as previously reported. The zeta-potential of the media was negatively charged and decreased from -23 to -35 mV with increasing surfactant/lipid load. Lower zeta-potential values (-16 mV) obtained for the structures formed during the lipid hydrolysis of the SNEDDS were probably due to the presence of calcium, which shields the surface, thereby reducing the charge. Conclusions. The diversity of these vesicles in terms of size, lamellarity, and internal organization advocate their important role during lipid digestion in the gastrointestinal milieu

Bacterial infection affects protein synthesis in primary lymphoid tissues and circulating lymphocytes of rats

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Speciation of uranyl nitrato complexes in acetonitrile and in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Complex formation between the uranyl ion and nitrate ions in acetonitrile and the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C(4)MiM][Tf2N]) has been studied by absorption, magnetic circular dichroism (MCD) and uranium L-III EXAFS spectroscopy. The experimental results point to the existence of a trinitrate species [UO2(NO3)(3)](-) with D-3h symmetry in both solvents. The atomic distances in the uranium(VI) coordination sphere for the trinitrato complex in acetonitrile are U-O-ax = 1.77 +/- 0. 01 angstrom and U-O-eq = 2.48 +/- 0.01 angstrom. EXAFS data show that the uranyl ion in the ionic liquid is surrounded by six oxygen atoms in the equatorial plane at a distance of 2.49 +/- 0.01 angstrom. The U-N distance of 2.92 +/- 0.01 angstrom indicates a bidentate coordination of the nitrate group in both solvents. A structural comparison is made between the uranyl trimtrato complex anion [UO2(NO3)(3)](-) and the uranyl tricarbonato complex anion [UO2(CO3)(3)](4-). No evidence is found for the presence of uranyl nitrato complexes in aqueous solution. The optical absorption, MCD and EXAFS spectra resemble those of the hydrated free uranyl ion. There are two axial oxygen atoms at 1.77 +/- 0.01 angstrom and five equatorial oxygen atoms at 2.41 +/- 0.01 angstrom. These values agree well with structural parameters obtained for the uranyl aqua ion.status: publishe

Protein Digestion, Absorption, and Metabolism.

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Quantitation in PET using isotopes emitting prompt single gammas: application to yttrium-86.

Several yttrium-90 labelled somatostatin analogues are now available for cancer radiotherapy. After injection, a large amount of the compound is excreted via the urinary tract, while a variable part is trapped in the tumour(s), allowing the curative effect. Unfortunately, the compound may also be trapped in critical tissues such as kidney or bone marrow. As a consequence, a method for assessment of individual biodistribution and pharmacokinetics is required to predict the maximum dose that can be safely injected into patients. However, (90)Y, a pure beta(-)particle emitter, cannot be used for quantitative imaging. Yttrium-86 is a positron emitter that allows imaging of tissue uptake using a PET camera. In addition to the positron, (86)Y also emits a multitude of prompt single gamma-rays, leading to significant overestimation of uptake when using classical reconstruction methods. We propose a patient-dependent correction method based on sinogram tail fitting using an (86)Y point spread function library. When applied to abdominal phantom acquisition data, the proposed correction method significantly improved the accuracy of the quantification: the initial overestimation of background activity by 117% was reduced to 9%, while the initial error in respect of kidney uptake by 84% was reduced to 5%. In patient studies, the mean discrepancy between PET total body activity and the activity expected from urinary collections was reduced from 92% to 7%, showing the benefit of the proposed correction method