Increased Oral Bioavailability of Resveratrol by Its Encapsulation in Casein Nanoparticles.

Resveratrol is a naturally occurring polyphenol that provides several health benefits including cardioprotection and cancer prevention. However, its biological activity is limited by a poor bioavailability when taken orally. The aim of this work was to evaluate the capability of casein nanoparticles as oral carriers for resveratrol. Nanoparticles were prepared by a coacervation process, purified and dried by spray-drying. The mean size of nanoparticles was around 200 nm with a resveratrol payload close to 30 µg/mg nanoparticle. In vitro studies demonstrated that the resveratrol release from casein nanoparticles was not affected by the pH conditions and followed a zero-order kinetic. When nanoparticles were administered orally to rats, they remained within the gut, displaying an important capability to reach the intestinal epithelium. No evidence of nanoparticle "translocation" were observed. The resveratrol plasma levels were high and sustained for at least 8 h with a similar profile to that observed for the presence of the major metabolite in plasma. The oral bioavailability of resveratrol when loaded in casein nanoparticles was calculated to be 26.5%, 10 times higher than when the polyphenol was administered as oral solution. Finally, a good correlation between in vitro and in vivo data was observed.

Lessons from 11C-dihydrotetrabenazine imaging in a xenograft mouse model of rat insulinoma: is PET imaging of pancreatic beta cell mass feasible?

BACKGROUND: The feasibility of beta cell mass (BCM) imaging and quantification with positron emission tomography (PET) in the pancreas is controversial. In an effort to shed some light on this topic, we have used a xenograft model of rat insulinoma (RIN) in mice, mimicking an intramuscular islet transplantation situation. METHODS: A total of 105 RIN cells were subcutaneously implanted in nude mice (N.=8). Tumor size and glycaemia levels were determined daily. Rat C-peptide was measured to demonstrate rat insulin production. PET imaging with 11C-(+)-α-dihydrotetrabenazine (11C-DTBZ) was done at 3 and 4 weeks and compared with 18F-FDG and 18F-DOPA studies in the same mice. Ex-vivo autoradiography with 11C-DTBZ was carried out in frozen sections of tumors. VMAT2 expression was measured by Western-blot and immunohistochemistry in tumors and RIN cells. RESULTS: Functional rat insulin production in mice was demonstrated by substantial decrease in glycaemia (<50 mg/dL by week 4) and rat C-peptide levels (7.2±2.6 ng/mL) similar to those measured in control rats. PET studies showed that tumor imaging with 11C-DTBZ at four (N.=8) and five (N.=5) weeks was negative; only bigger tumors could be seen with 18F-DOPA. In explanted tumors 11C-DTBZ autoradiography was negative, albeit VMAT2 expression measured by Western-blot and immunohistochemistry was lower than in cultured RIN cells. CONCLUSIONS: Although insulinomas are fully functional it does not seem feasible to use 11C-DTBZ for in-vivo measuring of BCM. This might either be due to inherent technical limitations of PET, decrease in VMAT2 expression in the tumors due to unknown reasons, or other biological limiting facts.

Comparison of staging using [68Ga]Ga-PSMA-11 PET/CT and histopathological results in intermediate- and high-risk prostate cancer patients treated with radical prostatectomy and pelvic lymph node dissection.

OBJECTIVE: To evaluate the diagnostic accuracy of [68Ga]Ga-PSMA-11 PET/CT (PET-PSMA) in local and loco-regional nodal staging compared with histopathological results in intermediate- and high-risk prostate cancer patients treated with radical prostatectomy (RP) and pelvic lymph node dissection (PLND). MATERIALS Y METHODS: A total of 122 intermediate- and high-risk prostate cancer (PCa) patients staged with PET-PSMA and treated with RP (36/122) and RP plus PLND (86/122) from December 2018 to December 2023 were included. Visual and semiquantitative analysis findings using the SUVmax of the molecular imaging were correlated with histopathological results. RESULTS: The primary tumor was visible by PET-PSMA in 96.7% of the patients. A positive correlation was found between PSA levels and SUVmax (Spearman's r: 0.303, p < 0.001). PET-PSMA detected nodal involvement in 25/89 patients (28.08%). The sensitivity, specificity, and diagnostic accuracy of PET-PSMA for detecting nodal involvement were 75%, 82.2%, and 80.9%, respectively. Patients with PSA levels >20 ng/ml, Gleason score ≥7b, ISUP grade >2, and extracapsular extension showed significantly higher SUVmax values. No differences were observed in SUVmax between risk groups or in other histopathological variables. CONCLUSIONS: PET-PSMA is an effective tool for the initial staging of intermediate- and high-risk PCa. SUVmax values were significantly higher in patients with unfavorable clinical features.

Decreased carbon-11-flumazenil binding in early Alzheimer's disease.

Neuronal loss in Alzheimer's disease, a better correlate of cognitive impairment than amyloid deposition, is currently gauged by the degree of regional atrophy. However, functional markers, such as GABA(A) receptor density, a marker of neuronal integrity, could be more sensitive. In post-mortem hippocampus, GABA(A) messenger RNA expression is reduced even in mild cognitive impairment. We measured whole-brain GABA(A) binding potential in vivo using [(11)C]-flumazenil positron emission tomography and compared GABA(A) binding with metabolic and volumetric measurements. For this purpose, we studied 12 subjects, six patients with early Alzheimer's disease and six healthy controls, with [(11)C]-flumazenil and [(18)F]-fluorodeoxyglucose positron emission tomography, as well as with high-resolution magnetic resonance imaging. Data were evaluated with both voxel-based parametric methods and volume of interest methods. We found that in early Alzheimer's disease, with voxel-based analysis, [(11)C]-flumazenil binding was decreased in infero-medial temporal cortex, retrosplenial cortex and posterior perisylvian regions. Inter-group differences reached corrected significance when using an arterial input function. Metabolism measured with positron emission tomography and volumetric measurements obtained with magnetic resonance imaging showed changes in regions affected in early Alzheimer's disease, but, unlike with [(11)C]-flumazenil binding and probably due to sample size, the voxel-based findings failed to reach corrected significance in any region of the brain. With volume of interest analysis, hippocampi and posterior cingulate gyrus showed decreased [(11)C]-flumazenil binding. In addition, [(11)C]-flumazenil hippocampal binding correlated with memory performance. Remarkably, [(11)C]-flumazenil binding was decreased precisely in the regions showing the greatest degree of neuronal loss in post-mortem studies of early Alzheimer's disease. From these data, we conclude that [(11)C]-flumazenil binding could be a useful marker of neuronal loss in early Alzheimer's disease.

Radiolabeled Risperidone microSPECT/CT Imaging for Intranasal Implant Studies Development.

The use of intranasal implantable drug delivery systems has many potential advantages for the treatment of different diseases, as they can provide sustained drug delivery, improving patient compliance. We describe a novel proof-of-concept methodological study using intranasal implants with radiolabeled risperidone (RISP) as a model molecule. This novel approach could provide very valuable data for the design and optimization of intranasal implants for sustained drug delivery. RISP was radiolabeled with 125I by solid supported direct halogen electrophilic substitution and added to a poly(lactide-co-glycolide) (PLGA; 75/25 D,L-Lactide/glycolide ratio) solution that was casted on top of 3D-printed silicone molds adapted for intranasal administration to laboratory animals. Implants were intranasally administered to rats, and radiolabeled RISP release followed for 4 weeks by in vivo non-invasive quantitative microSPECT/CT imaging. Percentage release data were compared with in vitro ones using radiolabeled implants containing either 125I-RISP or [125I]INa and also by HPLC measurement of drug release. Implants remained in the nasal cavity for up to a month and were slowly and steadily dissolved. All methods showed a fast release of the lipophilic drug in the first days with a steadier increase to reach a plateau after approximately 5 days. The release of [125I]I- took place at a much slower rate. We herein demonstrate the feasibility of this experimental approach to obtain high-resolution, non-invasive quantitative images of the release of the radiolabeled drug, providing valuable information for improved pharmaceutical development of intranasal implants.

Oral Immunogenicity of Enterotoxigenic Escherichia coli Outer Membrane Vesicles Encapsulated into Zein Nanoparticles Coated with a Gantrez® AN-Mannosamine Polymer Conjugate.

Enterotoxigenic Escherichia coli (ETEC) represents a major cause of morbidity and mortality in the human population. In particular, ETEC infections affect children under the age of five from low-middle income countries. However, there is no licensed vaccine against this pathogen. ETEC vaccine development is challenging since this pathotype expresses a wide variety of antigenically diverse virulence factors whose genes can be modified due to ETEC genetic plasticity. To overcome this challenge, we propose the use of outer membrane vesicles (OMVs) isolated from two ETEC clinical strains. In these OMVs, proteomic studies revealed the presence of important immunogens, such as heat-labile toxin, colonization factors, adhesins and mucinases. Furthermore, these vesicles proved to be immunogenic after subcutaneous administration in BALB/c mice. Since ETEC is an enteropathogen, it is necessary to induce both systemic and mucosal immunity. For this purpose, the vesicles, free or encapsulated in zein nanoparticles coated with a Gantrez®-mannosamine conjugate, were administered orally. Biodistribution studies showed that the encapsulation of OMVs delayed the transit through the gut. These results were confirmed by in vivo study, in which OMV encapsulation resulted in higher levels of specific antibodies IgG2a. Further studies are needed to evaluate the protection efficacy of this vaccine approach.

Preclinical safety of negatively charged microspheres (NCMs): Optimization of radiolabeling for in vivo and ex vivo biodistribution studies after topical administration on full-thickness wounds in a rat model.

Negatively charged microspheres (NCMs) are postulated as a new form of treatment for chronic wounds. Despite the efficacy shown at clinical level, more studies are required to demonstrate their safety and local effect. The objective of the work was to confirm the lack of NCM systemic absorption performing a biodistribution study of the NCMs in an open wound rat animal model. To this end, radiolabeling of NCMs with technetium-99 m was optimized and biodistribution studies were performed by in vivo SPEC/CT imaging and ex vivo counting during 24 h after topical administration. The studies were performed on animals treated with a single or repeated dose to study the effect of macrophages during a prolonged treatment. NCM radiolabeling was achieved in a simple, efficient and stable manner with high yield. SPECT/CT images showed that almost all NCMs (about 85 %) remained on the wound for 24 h either after single or multiple administrations. Ex vivo biodistribution studies confirmed that there was no accumulation of NCMs in any organ or tissue except in the wound area, suggesting a lack of absorption. In conclusion, NCMs can be considered safe as local wound treatment since they remain at the administration area.

A new animal model of atrophy-hypertrophy complex and liver damage following Yttrium-90 lobar selective internal radiation therapy in rabbits.

Lobar selective internal radiation therapy (SIRT) is widely used to treat liver tumors inducing atrophy of the treated lobe and contralateral hypertrophy. The lack of animal model has precluded further investigations to improve this treatment. We developed an animal model of liver damage and atrophy-hypertrophy complex after SIRT. Three groups of 5-8 rabbits received transportal SIRT with Yttrium 90 resin microspheres of the cranial lobes with different activities (0.3, 0.6 and 1.2 GBq), corresponding to predicted absorbed radiation dose of 200, 400 and 800 Gy, respectively. Another group received non-loaded microspheres (sham group). Cranial and caudal lobes volumes were assessed using CT volumetry before, 15 and 30 days after SIRT. Liver biochemistry, histopathology and gene expression were evaluated. Four untreated rabbits were used as controls for gene expression studies. All animals receiving 1.2 GBq were euthanized due to clinical deterioration. Cranial SIRT with 0.6 GBq induced caudal lobe hypertrophy after 15 days (median increase 34% -ns-) but produced significant toxicity. Cranial SIRT with 0.3 GBq induced caudal lobe hypertrophy after 30 days (median increase 82%, p = 0.04). No volumetric changes were detected in sham group. Transient increase in serum transaminases was detected in all treated groups returning to normal values at 15 days. There was dose-dependent liver dysfunction with bilirubin elevation and albumin decrease. Histologically, 1.2 GBq group developed permanent severe liver damage with massive necrosis, 0.6 and 0.3 GBq groups developed moderate damage with inflammation and portal fibrosis at 15 days, partially recovering at 30 days. There was no difference in the expression of hepatocyte function and differentiation genes between 0.3 GBq and control groups. Cranial SIRT with 0.3 GBq of 90Y resin microspheres in rabbits is a reliable animal model to analyse the atrophy-hypertrophy complex and liver damage without toxicity.

Ultra-low dose whole-body CT for attenuation correction in a dual tracer PET/CT protocol for multiple myeloma.

PURPOSE: To investigate within phantoms the minimum CT dose allowed for accurate attenuation correction of PET data and to quantify the effective dose reduction when a CT for this purpose is incorporated in the clinical setting. METHODS: The NEMA image quality phantom was scanned within a large parallelepiped container. Twenty-one different CT images were acquired to correct attenuation of PET raw data. Radiation dose and image quality were evaluated. Thirty-one patients with proven multiple myeloma who underwent a dual tracer PET/CT scan were retrospectively reviewed. 18F-fluorodeoxyglucose PET/CT included a diagnostic whole-body low dose CT (WBLDCT: 120 kV-80mAs) and 11C-Methionine PET/CT included a whole-body ultra-low dose CT (WBULDCT) for attenuation correction (100 kV-40mAs). Effective dose and image quality were analysed. RESULTS: Only the two lowest radiation dose conditions (80 kV-20mAs and 80 kV-10mAs) produced artifacts in CT images that degraded corrected PET images. For all the other conditions (CTDIvol ≥ 0.43 mGy), PET contrast recovery coefficients varied less than ± 1.2%. Patients received a median dose of 6.4 mSv from diagnostic CT and 2.1 mSv from the attenuation correction CT. Despite the worse image quality of this CT, 94.8% of bone lesions were identifiable. CONCLUSION: Phantom experiments showed that an ultra-low dose CT can be implemented in PET/CT procedures without any noticeable degradation in the attenuation corrected PET scan. The replacement of the standard CT for this ultra-low dose CT in clinical PET/CT scans involves a significant radiation dose reduction.

Mannosylated Nanoparticles for Oral Immunotherapy in a Murine Model of Peanut Allergy.

Peanut allergy is one of the most prevalent and severe of food allergies with no available cure. The aim of this work was to evaluate the potential of an oral immunotherapy based on the use of a roasted peanut extract encapsulated in nanoparticles with immunoadjuvant properties. For this, a polymer conjugate formed by the covalent binding of mannosamine to the copolymer of methyl vinyl ether and maleic anhydride was first synthetized and characterized. Then, the conjugate was used to prepare nanoparticles with an important capability to diffuse through the mucus layer and reach, in a large extent, the intestinal epithelium, including Peyer's patches. Their immunotherapeutic potential was evaluated in a model of presensitized CD1 mice to peanut. After completing therapy, mice underwent an intraperitoneal challenge with peanut extract. Nanoparticle-treatment was associated with both less serious anaphylaxis symptoms and higher survival rates than control, confirming the protective effect of this formulation against the challenge.

Modulation of the fate of zein nanoparticles by their coating with a Gantrez® AN-thiamine polymer conjugate.

The aim of this work was to evaluate the mucus-permeating properties of nanocarriers using zein nanoparticles (NPZ) coated with a Gantrez® AN-thiamine conjugate (GT). NPZ were coated by incubation at different GT-to-zein ratios: 2.5% coating with GT (GT-NPZ1), 5% (GT-NPZ2) and 10% (GT-NPZ3). During the process, the GT conjugate formed a polymer layer around the surface of zein nanoparticles. For GT-NPZ2, the thickness of this corona was estimated between 15 and 20 nm. These nanocarriers displayed a more negative zeta potential than uncoated NPZ. The diffusivity of nanoparticles was evaluated in pig intestinal mucus by multiple particle tracking analysis. GT-NPZ2 displayed a 28-fold higher diffusion coefficient within the mucus layer than NPZ particles. These results align with in vivo biodistribution studies in which NPZ displayed a localisation restricted to the mucus layer, whereas GT-NPZ2 were capable of reaching the intestinal epithelium. The gastro-intestinal transit of mucoadhesive (NPZ) and mucus-permeating nanoparticles (GT-NPZ2) was also found to be different. Thus, mucoadhesive nanoparticles displayed a significant accumulation in the stomach of animals, whereas mucus-penetrating nanoparticles appeared to exit the stomach more rapidly to access the small intestine of animals.

The effect of thiamine-coating nanoparticles on their biodistribution and fate following oral administration.

Thiamine-coated nanoparticles were prepared by two different preparative methods and evaluated to compare their mucus-penetrating properties and fate in vivo. The first method of preparation consisted of surface modification of freshly poly(anhydride) nanoparticles (NP) by simple incubation with thiamine (T-NPA). The second procedure focused on the preparation and characterization of a new polymeric conjugate between the poly(anhydride) backbone and thiamine prior the nanoparticle formation (T-NPB). The resulting nanoparticles displayed comparable sizes (about 200 nm) and slightly negative surface charges. For T-NPA, the amount of thiamine associated to the surface of the nanoparticles was 15 µg/mg. For in vivo studies, nanoparticles were labelled with either 99mTc or Lumogen® Red. T-NPA and T-NPB moved faster from the stomach to the small intestine than naked nanoparticles. Two hours post-administration, for T-NPA and T-NPB, >30% of the given dose was found in close contact with the intestinal mucosa, compared with a 13.5% for NP. Interestingly, both types of thiamine-coated nanoparticles showed a greater ability to cross the mucus layer and interact with the surface of the intestinal epithelium than NP, which remained adhered in the mucus layer. Four hours post-administration, around 35% of T-NPA and T-NPB were localized in the ileum of animals. Overall, both preparative processes yielded thiamine decorated carriers with similar physico-chemical and biodistribution properties, increasing the versatility of these nanocarriers as oral delivery systems for a number of biologically active compounds.

(13)N-ammonia PET as a measurement of hindlimb perfusion in a mouse model of peripheral artery occlusive disease.

UNLABELLED: Peripheral arterial occlusive disease (PAOD) is a leading cause of mortality and morbidity in the western world. The development of noninvasive methods for assessment and comparison of the efficacy of novel therapies in animal models is of great importance. METHODS: Hindlimb ischemia was induced in nude mice by ligation and excision of the left femoral artery (n = 5) or the left iliac artery (n = 10). Assessment of limb perfusion was performed by small-animal PET analysis after intravenous injection of (13)N-ammonia between 24 h and 30 d after surgery using the ratio of perfusion between the left limb (ischemic) and the right limb (control). Activity concentration per area unit was calculated in regions of interest placed on 1-mm-thick images for numeric calculations, and the iliac and the femoral models were compared. In addition, histopathologic studies were performed to assess the degree of necrosis (hematoxylin-eosin) and fibrosis (sirius red). Immunohistochemistry analyses for identification of arterioles (alpha-smooth muscle actin) and endothelium-capillaries-(Bandeiraea simplicifolia I [BS-I] lectin) were also performed. RESULTS: Perfusion in both hindlimbs of control animals was similar (median of the left-to-right ratio = 0.99). Twenty-four hours after ischemia, perfusion of the ischemic limb (% mean +/- SD) was 33.3 +/- 10.6 and 22.1 +/- 9.9 in the femoral and iliac models, respectively. Spontaneous recovery of perfusion in the hindlimb that underwent surgery was significantly lower in the iliac model at day +15 (73.2 +/- 15.5 vs. 51.9 +/- 11.3; P < 0.01). Fibrosis increased progressively until day +30, whereas muscle necrosis was maximal at day +7 with a moderate reduction by day +30. In accordance with this positive effect, there was a statistically significant increase in the area covered with smooth muscle-coated vessels (arterioles) at day +30 in comparison with day 7 (P < 0.05). In addition, a correlation between (13)N-ammonia uptake and the amount of necrosis (r = -0.73; P = 0.06) and fibrosis (r = -0.67; P = 0.05) at day +30 was found. CONCLUSION: (13)N-Ammonia imaging allows semiquantitative evaluation of hindlimb perfusion in surgical mouse models of acute hindlimb ischemia. Although spontaneous perfusion recovery is observed in both models, the iliac model shows a substantially lower recovery and is hence better suited for assessment of new therapeutic strategies for acute hindlimb ischemic disease.

Simple automated system for simultaneous production of 11C-labeled tracers by solid supported methylation.

We herein describe a simple setup for the automated simultaneous synthesis of L-[methyl-11C]methionine and N-[methyl-11C]choline by solid-supported methylation. The setup is extremely simple and easy to adapt to other automated systems and due to its versatility, the method can be utilized for the production of other radiopharmaceuticals requiring a simple [11C]methylation step. Furthermore, it can be used for multiple simultaneous synthesis.

In vivo study of the mucus-permeating properties of PEG-coated nanoparticles following oral administration.

The aim of this work was to investigate the mucus-permeating properties of poly(ethyleneglycol)-coated nanoparticles prepared from the copolymer of methyl vinyl ether and maleic anhydride (Gantrez® AN) after oral administration in rats. Nanoparticles were "decorated" with PEGs of different molecular masses (PEG2000, PEG6000 and PEG10000) at a PEG-to-polymer ratio of 0.125. All the PEG-coated nanoparticles displayed a mean size of ∼150 nm, slightly negative ζ values and a "brush" conformation as determined from the calculation of the PEG density. For in vivo studies, nanoparticles were labelled with either (99m)Tc or fluorescent tags. Naked nanoparticles displayed a higher ability to interact with the mucosa of the stomach than with the small intestine. However, these interactions were restricted to the mucus layer covering the epithelial surface, as visualised by fluorescence microscopy. On the contrary, PEG-coated nanoparticles moved rapidly to the intestine, as determined by imaging, and, then, were capable to develop important interactions with the mucosa, reaching the surface of the epithelium. These mucus permeating properties were more intense for nanoparticles coated with PEG2000 or PEG6000 than with PEG10000. However, the capability of nanocarriers to develop adhesive interactions within the mucosa decreased when prepared at excessive PEG densities.

Molecular imaging techniques to study the biodistribution of orally administered (99m)Tc-labelled naive and ligand-tagged nanoparticles.

PURPOSE: Study by molecular imaging the biodistribution of poly(anhydride) nanoparticles after oral administration. PROCEDURES: Poly (anhydride) nanoparticles (NP) and cyclodextrin-tagged nanoparticles (CD-NP) were radiolabelled with (99m)Tc. Radiochemical purity was measured with a double-solvent chromatography system and the absence of undesirable components was confirmed by size and polydispersion measurement of the technetium-labelled nanoparticles by photon correlation spectroscopy. Single photon emission computed tomography (SPECT) fused computed tomography (CT) in vivo molecular imaging was used for biodistribution studies in small animals. RESULTS: SPECT-CT images revealed activity only in the gastrointestinal tract. Thirteen percent of the given dose of CD-NP and 3% of the given dose of conventional NP were found in the stomach at 8 h. CONCLUSION: No evidence of translocation or distribution out of gastrointestinal tract was found. CD-NP moved significantly more slowly inside the gut than conventional NP, probably due to their physico-chemical structure that allows stronger interactions with the gut mucosa.

Design and performance evaluation of single-use whole-sterile "plug & play" kits for routine automated production of [(11)C]choline and [(11)C]methionine with radiopharmaceutical quality.

We herein describe the design and performance evaluation of single-use whole-sterile "plug & play" kits for routine automated production of [(11)C]methionine and [(11)C]choline for human use. Kits were designed for maximal simplicity and ease of using modules from Eckert & Ziegler Modular Lab System. The use of all-disposable sterile medical-grade material, helps ensure safety and cGMP compliance. The quick set-up and removal ("plug & play") also reduces radiation burden to operator.

Dual tracer 11C-choline and FDG-PET in the diagnosis of biochemical prostate cancer relapse after radical treatment.

PURPOSE: The purpose of this study was to evaluate a dual tracer 2-deoxy-2-[F-18]fluoro-D: -glucose (FDG) and (11)C-choline positron emission tomography (PET) protocol in the detection of biochemical prostate cancer relapse. PROCEDURES: Seventy-three patients (median Prostate Specific Antigen (PSA) Test value 2.7 ng/ml (1.1-5.4)) after radical treatment. PET scans were performed by means of a ECAT-Exact HR+ in the first 18 patients and in a PET/computed tomography Biograph II in the remaining 55 patients. RESULTS: The sensitivity of (11)C-choline and FDG was 60.6% and 31%. In PSA levels over 1.9 ng/ml, sensitivity increased to 80% and 40%, respectively. In the group receiving adjuvant hormone therapy, the diagnostic yields were 71.2% and 43%, respectively. While (11)C-choline-PET could not differentiate well and poorly differentiated Gleason score patients, FDG-PET results were almost significant (p = 0.058). CONCLUSIONS: A PSA value higher than 1.9 ng/ml determines a significant increase in the diagnostic yield. Adjuvant hormonotherapy has no influence on the PET results. FDG has a better correlation with the Gleason score than (11)C-choline.

Synthesis of S-[13N]nitrosoglutathione (13N-GSNO) as a new potential PET imaging agent.

In the present paper, a fast and reproducible method for the synthesis of S-[(13)N]nitrosoglutathione is reported for the first time. The labeling strategy is based on the production of [(13)N]NO(3)(-) via the (16)O(p,alpha)(13)N nuclear reaction in water, as opposed to the standardized production of [(13)N]NH(4)(+) in 2mM aqueous ethanol. Following the reduction of [(13)N]NO(3)(-) to [(13)N]NO(2)(-), the reaction with glutathione in the presence of hydrochloric acid led to the desired radiotracer with a good radiochemical yield (24.2+/-2.0% end of synthesis, n=5) in a short production time (3min from the end of bombardment).

Bioadhesive properties and biodistribution of cyclodextrin-poly(anhydride) nanoparticles.

This work describes the preparation, characterization and evaluation of the nanoparticles formed by the copolymer of methyl vinyl ether and maleic anhydride (Gantrez) AN) and cyclodextrins, including beta-cyclodextrin (CD) hydroxypropyl-beta-cyclodextrin (HPCD) and 6-monodeoxy-6-monoamino-beta-cyclodextrin (NHCD). The cyclodextrin-poly(anhydride) nanoparticles were prepared by a solvent displacement method and characterized by measuring the size, zeta potential, morphology and composition. For bioadhesion studies, nanoparticles were fluorescently labelled with rhodamine B isothiocianate (RBITC). For in vivo imaging biodistribution studies, (99m)Tc-labelled nanoparticles were used. Nanoparticles displayed a size of about 150nm and a cyclodextrin content which was found optimal under the following experimental conditions: cyclodextrin/poly(anhydride) ratio of 0.25 by weight, 30min of incubation time between the cyclodextrin and the polymer. Moreover, the oligosaccharide content was higher with CD than with NHCD and HPCD. Overall, cyclodextrin-poly(anhydride) nanoparticles displayed homogeneous bioadhesive interactions within the gut. The intensity of these interactions was higher than for control nanoparticles. The high bioadhesive capacity was observed for HPCD-NP and NHCD-NP which can be related with their rough morphology and, thus, a higher specific surface than for smooth nanoparticles (CD-NP). Finally, from in vivo studies, no evidence of translocation of distribution to other organs was observed when these nanoparticles were orally administered.