Effects of Particle Size of Curcumin Solid Dispersions on Bioavailability and Anti-Inflammatory Activities.

The delivery of curcumin (CUR) using the solid dispersion system (CUR solid dispersions; C-SDs) has been shown to improve CUR bioavailability. However, it is unclear how different particle sizes of C-SDs affect the bioavailability and biological activities of CUR. Hence, we prepared C-SDs in different sizes using food-grade excipients and evaluated their bioavailability and biological activities. By pulverizing large particle sizes of C-SDs using zirconia beads, we successfully prepared C-SDs I-IV (particle size: (I) 120, (II) 447, (III) 987, (IV) 1910 nm). When administrated orally in rats, the bioavailability of CUR was increased with decreasing C-SDs size, most likely by improving its solubility in micelles. When administrated intravenously in rats, blood concentrations of CUR were increased with increasing particle size, suggesting that larger C-SDs presumably control the metabolic conversion of CUR. In RAW264 cells, more CUR was taken up by cells as their sizes reduced, and the more potent their anti-inflammatory activities were, suggesting that smaller C-SDs were taken up through a number of cellular uptake pathways. Altogether, the present study showed an evident effect of C-SDs size on their bioavailability and anti-inflammatory activities-information that serves as a basis for improving the functionality of CUR.

Pharmacokinetics of Morphine in Rats with Adjuvant-induced Arthritis.

We investigated the in vivo dynamics and analgesic effect of morphine using an adjuvant-induced arthritis (AA) rat as a model of chronic inflammation. Morphine generally binds to µ-opioid receptors in the brain to exert its effects. After several minutes, it is metabolized by glucuronidation via a UDP-glucuronosyltransferase (UGT). Here, we showed that in AA rats, UGT activity in liver microsomes was reduced. Morphine-free serum fractions in AA rats were also decreased (control, 84.9%; AA, 63.9%) and the expression of ATP-binding cassette, sub-family B (MDR/TAP), member 1 (ABCB1), which plays a crucial role in morphine bile excretion, decreased to 23.0% that of the control group. However, we observed no significant difference between the AA and control groups regarding blood concentrations of morphine and morphine-3-glucuronide. In contrast, the analgesic effect of morphine increased 4-fold in AA rats. Our results showed that the pharmacokinetics of morphine is not changed, but the pharmacodynamics of morphine is enhanced in chronic inflammation.

Gaf-1b is an alternative splice variant of Gaf-1/Rip11.

Gaf-1/Rip11 encoded by the clone KIAA0857 participates in endosomal recycling through the interaction with both gamma-SNAP, a member of the soluble NSF attachment protein family, and a small GTPase, Rab11. Gaf-1/Rip11 and other Rab11-interacting proteins constitute a novel protein family that is involved in the endocytic pathways. Here we report the presence of an alternative splice variant of Gaf-1/Rip11 named Gaf-1b. Gaf-1b also interacts with gamma-SNAP and is expressed ubiquitously in tissues except for liver. Subcellular fractionation analysis revealed that Gaf-1b, as well as Gaf-1/Rip11, is mainly present in the microsomal fraction. Overexpression of Gaf-1b, like that of Gaf-1/Rip11, affected the morphology of recycling endosomes. These results suggest that Gaf-1b has a similar function to Gaf-1/Rip11.

Mapping of functional domains of gamma-SNAP.

gamma-Soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (gamma-SNAP) is capable of stabilizing a 20 S complex consisting of NSF, alpha-SNAP, and SNAP receptors (SNAREs), but its function in vesicular transport is not fully understood. Our two-hybrid analysis revealed that gamma-SNAP, unlike alpha-SNAP, interacts directly with NSF, as well as Gaf-1/Rip11, but not with SNAREs. Gaf-1/Rip11 is a gamma-SNAP-associated factor that belongs to the Rab11-interacting protein family. To gain insight into the molecular basis for the interactions of gamma-SNAP with NSF and Gaf-1/Rip11, we determined the regions of the three proteins involved in protein-protein interactions. gamma-SNAP bound to NSF via its extreme C-terminal region, and the full-length NSF was needed to interact with gamma-SNAP. Both the N-terminal and C-terminal regions of gamma-SNAP were required for the binding to Gaf-1/Rip11. Gaf-1/Rip11 bound to gamma-SNAP via its C-terminal domain comprising a putative coiled-coil region. Although the C-terminal domain of Gaf-1/Rip11 also interacts with Rab11, the binding of gamma-SNAP and Rab11 to Gaf-1/Rip11 was not mutually exclusive. Rather, Gaf-1/Rip11 was capable of serving a link between gamma-SNAP and Rab11. A complex comprising gamma-SNAP and Gaf-1/Rip11 was disassembled in a process coupled to NSF-mediated ATP hydrolysis, suggesting that the interaction between gamma-SNAP and Gaf-1/Rip11 is of functional significance.