Decorporation of systemically distributed americium by a novel orally administered diethylenetriaminepentaacetic acid (DTPA) formulation in beagle dogs.

Novel decorporation agents are being developed to protect against radiological accidents and terrorists attacks. Radioactive americium is a significant component of nuclear fallout. Removal of large radioactive materials, such as 241Am, from exposed persons is a subject of significant interest due to the hazards they pose. The objective of this study was to evaluate the dose-related efficacy of daily doses of NanoDTPA™ Capsules for decorporating Am administered intravenously as a soluble citrate complex to male and female beagle dogs. In addition, the efficacy of the NanoDTPA™ Capsules for decorporating 241Am was directly compared to intravenously administered saline and DTPA. Animals received a single IV administration of 241Am(III)-citrate on Day 0. One day after radionuclide administration, one of four different doses of NanoDTPA™ Capsules [1, 2, or 6 capsules d(-1) (30 mg, 60 mg, or 180 mg DTPA) or 2 capsules BID], IV Zn-DTPA (5 mg kg(-1) pentetate zinc trisodium) as a positive control, or IV saline as a placebo were administered. NanoDTPA™ Capsules, IV Zn-DTPA, or IV saline was administered on study days 1-14. Animals were euthanized on day 21. A full necropsy was conducted, and liver, spleen, kidneys, lungs and trachea, tracheobronchial lymph nodes (TBLN), muscle samples (right and left quadriceps), gastrointestinal (GI) tract (stomach plus esophagus, upper and lower intestine), gonads, two femurs, lumbar vertebrae (L1-L4), and all other soft tissue remains were collected. Urinary and fecal excretion profiles were increased approximately 10-fold compared to those for untreated animals. Tissue contents were decreased compared to untreated controls. In particular, liver content was decreased by approximately eightfold compared to untreated animals. The results from this study further demonstrate that oral NanoDTPA™ Capsules are equally efficient compared to IV Zn-DTPA in decorporation of actinides.

Large intestine-targeted, nanoparticle-releasing oral vaccine to control genitorectal viral infection.

Both rectal and vaginal mucosal surfaces serve as transmission routes for pathogenic microorganisms. Vaccination through large intestinal mucosa, previously proven protective for both of these mucosal sites in animal studies, can be achieved successfully by direct intracolorectal (i.c.r.) administration, but this route is clinically impractical. Oral vaccine delivery seems preferable but runs the risk of the vaccine's destruction in the upper gastrointestinal tract. Therefore, we designed a large intestine-targeted oral delivery with pH-dependent microparticles containing vaccine nanoparticles, which induced colorectal immunity in mice comparably to colorectal vaccination and protected against rectal and vaginal viral challenge. Conversely, vaccine targeted to the small intestine induced only small intestinal immunity and provided no rectal or vaginal protection, demonstrating functional compartmentalization within the gut mucosal immune system. Therefore, using this oral vaccine delivery system to target the large intestine, but not the small intestine, may represent a feasible new strategy for immune protection of rectal and vaginal mucosa.

Identification of stabilized dynorphin derivatives for suppressing tolerance in morphine-dependent rats.

PURPOSE: Modulatory actions on morphine-induced effects, such as tolerance and withdrawal, have been noted for dynorphin A(1-13) [Dyn A(1-13)] and similar peptides. These are currently of limited therapeutic potential due to extensive metabolism by human metabolic enzymes resulting in a half-life of less than 1 min in human plasma. The purpose of this study was to identify stabilized dynorphin A (Dyn A) derivatives, to determine their metabolic routes in human plasma, and to assess whether the pharmacodynamic activity is retained. METHODS: The stability of peptides in human plasma was tested using in vitro metabolism studies with and without enzyme inhibitors. Identification of the generated metabolites was performed by mass spectrometry after high performance liquid chromatography (HPLC) separation. The in vivo activity of a stabilized dynorphin was tested by tail-flick assay in morphine-tolerant rats. RESULTS: Though amidation of the Dyn A(1-13) was able to stop the majority of C-terminal degradation, metabolism of Dyn A(1-10) amide continued by captopril sensitive enzymes, suggesting that Dyn A(1-13) amide is a better candidate for additional stabilization. Two Dyn A(1-13) amide derivatives further stabilized at the N-terminal end, [D-Tyr1]-Dyn A(1-13) amide and [N-Met-Tyr1]-Dyn A(1-13) amide, showed half-lives in plasma of 70 and 130 min, respectively. The most stable derivative [N-Met-Tyr1]-Dyn A(1-13) amide was tested successfully for retention of the pharmacological activity in modulating antinociceptive activity. CONCLUSIONS: [N-Met-Tyr1]-Dyn A(1-13) amide showed significant stability and antinociceptive activity in the tail-flick test, thus pointing to the clinical potential of this derivative in the management of pain as well as its potential activity in suppressing opiate tolerance and withdrawal.

Cytoprotective role of taurine in a renal epithelial cell culture model.

Taurine (TAU) is a sulfur-containing amino acid that has been shown to decrease during aging and is believed to be important for cytoprotection. A decrease in TAU could exacerbate the accumulation of free radical-induced damage that may lead to cell death during the aging process. We have shown previously that TAU directly inhibits dopamine (DA) and (-)-3-(3,4-dihydroxyphenyl)-L-alanine (L-dopa) oxidation. Experiments were conducted to establish a cytoprotective role for TAU. Porcine renal epithelial cells were treated for 1 hr with iron and catecholamines (L-dopa and DA) to produce cytotoxicity by a free radical and quinone mechanism in the absence and presence of 10 or 20mM TAU. Viability assays, protein, and DNA measurements were performed after a 24hr recovery period. In some experiments, cells were extracted immediately after the insult for DA and TAU content measurements using high performance liquid chromatography with electrochemical detection. Catecholamine-induced cytotoxicity caused a 50% loss in cell viability, and 10 or 20mM TAU provided significant protection from cytotoxicity and maintained the functional integrity of the cells. Photomicrographs showed attenuation in cell loss and swelling in the presence of TAU. Pretreatment with 1mM TAU followed by exposure to iron and L-dopa in the presence of 1mM TAU caused a moderate but non-significant increase in cell survival. These data conclusively show that TAU can play a cytoprotective role in the LLC-PK(1) cell culture model.