Ultrabright NIR fluorescent mesoporous silica nanoparticles

Near-infrared (NIR) water-dispersible fluorescent tags are of big importance for biomedical imaging. Bright, stable, biocompatible NIR fluorescent nanoparticles have great translation potential to improve diagnosis of early stages of different diseases. Here we report on the synthesis of exceptionally bright ("ultrabright") fluorescent meso(nano)porous silica nanoparticles of 28 ± 3 nm in diameter. The NIR fluorescent dye LS277 is encapsulated inside these silica nanoparticles. The wavelengths of the maximum excitation/fluorescence of the particles are 804/815 nm. The absorptivity coefficient of the particles is 2.1 × 10⁸ M^-1 cm^-1 at 805 nm and the quantum yield of the dye increased by a factor of 5 after encapsulating to 1.5%. The fluorescent brightness of these particles is more than 2000× higher than the fluorescence of one molecule of LS277 in water. When exited in NIR spectral region (>700 nm), these particles are up to 4× brighter than QD800 commercial quantum dots emitting at 800 nm. We demonstrate that the synthesized NIR mesoporous silica nanoparticles easily internalize 4T1luc breast tumor cells, and remain bright for more than 9 weeks whereas the dye is completely bleached by that time.

Bioactivity of beaver castoreum constituents using principal components analysis

North American beaver (Castor canadensis) were observed to sniff from the water and make land visits to some synthetic chemical components of castoreum placed on experimental scent mounds (ESM). In previous analysis, the elicitation (presence/absence), completeness, and/or strength (number, duration) of these key responses served as separate measures of biological activity. In this paper, we used principal components analysis (PCA) to combine linearly six related measures of observed response and one index of overnight visitation calculated over all trials. The first principal component accounted for a majority of the variation and allowed ranking of the samples based on their composite bioactivity. A second PCA, based only on response trials (excluding trials with no responses), showed that responses to the synthetic samples, once elicited, did not vary greatly in completeness or strength. None of the samples evoked responses as complete or strong as the castoreum control. Castoreum also elicited more multiple land visits (repeated visits to the ESM by the same individual or by more than one family member) than the synthetic samples, indicating that an understanding of the castoreum chemosignal requires consideration of responses by the family unit, and not just the land visit by the initial responder.

Matrix protein of vesicular stomatitis virus: a potent inhibitor of vascular endothelial growth factor and malignant ascites formation

Malignant ascites is common in various types of cancers and is difficult to manage. Vascular endothelial growth factor (VEGF) has a pivotal role in malignant ascites. The matrix protein of vesicular stomatitis virus (VSVMP) has been shown to inhibit host gene expression and induce the apoptosis of cancer cells. The present study was designed to determine whether VSVMP suppresses the formation of ascites in ascites-producing peritoneal carcinomatosis. BALB/c female mice, 6-8 weeks old, bearing peritoneal tumors of H22 or MethA cells received an intraperitoneal administration of 50 μg VSVMP/250 μg liposome complexes, 50 μg empty plasmid/250 μg liposome complexes or 0.9% NaCl solution, respectively, every 2 days for 3 weeks. Administration of VSVMP resulted in a significant inhibition in ascites formation, improvement in health condition and prolonged survival of the treated mice. Decreased peritoneum osmolarity and reduced tumor vascularity coincided with dramatic reductions in the VEGF level in ascites fluid and plasma. Examination of floating tumor cells collected from the peritoneal wash revealed an apparently increased number of apoptotic cells and profound downregulation of VEGF mRNA in the VSVMP-treated mice. Our data indicate for the first time that in BALB/c mice bearing H22 or MethA cell peritoneal tumors, VSVMP may inhibit VEGF production and suppress angiogenesis, consequently abolishing ascites formation.

The Control of Mineralization on Natural and Implant Surfaces

The generation of minerals such as calcium phosphates on the surfaces of dental and joint replacement implants is beneficial since the facilitation of bone formation permits their fixation. In contrast, the prevention of crystallization is desired on other surfaces such as kidney and cardiac valve prostheses. A key to the development of successful biomaterials is therefore an understanding of the factors that control crystal nucleation, growth and dissolution in aqueous solution. The Constant Composition method was used to investigate the influence of factors such as solution composition, ionic strength, pH and temperature on the crystallization and dissolution of the calcium phosphates, brushite (DCPD), octacalcium phosphate (OCP), hydroxyapatite (HAP) and fluorapatite (FAP). In parallel with these studies, a contact angle method along with surface tension component theory was employed to investigate the roles of interfacial free energy in mineralization and demineralization. Values of the interfacial tensions, -4.2, 4.3, 10.4 and 18.5 mJm-2 obtained from contact angle measurements for DCPD, OCP, HAP and FAP, respectively, compare well with those calculated from dissolution kinetics experiments and provide information concerning the growth and dissolution mechanisms. The exploitation of these approaches is illustrated in studies of the coating of specific calcium phosphate phases on titanium metal and alloy surfaces and nucleation and growth of OCP on polymer surfaces modified by silanization to produce amine- and carboxylterminated end groups. In all these reactions involving the calcium phosphates, concomitant dissolution reactions are often involved. Constant Composition kinetic studies have shown that the rate of these reactions decrease markedly with time despite a sustained driving force, and eventually, the rates approach zero even though crystals remain in the undersaturated solutions. Dissolution can be reinitiated by exposing the crystals to the solutions of different undersaturations. These results suggest that dislocation sizes play a significant role in the dissolution kinetic processes.

Exposure-response (E-R) analysis to facilitate phase III (P3) dose selection for AMG 479 (A479) in combination with gemcitabine (G) to treat metastatic pancreatic cancer (mPC)

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Background: A479 is an investigational, fully human monoclonal antibody against IGF1R. In a phase II study, 125 pts with mPC were randomized 1:1:1 to A479, placebo (P), or conatumumab in combination with G. Addition of A479 (12 mg/kg IV, Q2W) to G (1000 mg/m2) showed evidence of improved OS and PFS (Kindler, JCO 2010:28 abstr 4035). An E-R analysis was done to inform P3 dose selection for A479.

Methods: A population PK model of A479 was constructed using data from multiple studies. An E-R analysis was performed with pts from the A479+G and P+G arms (∼40 pts/arm). The effect of estimated steady-state area under the curve (AUCss) on OS and PFS was evaluated with a Cox proportional hazard model. Effects of potential confounding factors on OS- AUCss and PFS-AUCss associations were assessed by multivariate analysis. Exposure-safety data were analyzed with descriptive statistics and linear regression. P3 doses for A479 were explored with Monte Carlo simulations using population PK and parametric survival models.

Results: There was a positive association between OS or PFS and higher AUCss in the A479+G arm (P<0.001, <0.001) that remained even when data from the A479+G and P+G arms were combined (P=0.033, 0.022). Pts with AUCss ≥ median (19.2 mg·h/μL) had longer median OS and PFS (16.0, 7.6 months) than pts with AUCss < median (4.7, 1.9 months). OS-AUCss and PFS-AUCss associations were significant after adjusting for potential confounding factors. Sensitivity E-R analyses were done to confirm the modeling results. The incidence of most adverse events was similar between the AUCss < and ≥ median groups, although the incidence of grade ≥3 hyperglycemia, neutropenia, and thrombocytopenia trended higher in pts with AUCss ≥ median. Population PK indicated 1.7-fold higher clearance of A479 in mPC than non-mPC pts. No G-A479 PK interactions were identified. PK simulations showed similar AUCss of A479 in mPC pts at 20 mg/kg and in non-mPC pts at 12 mg/kg. Simulations projected improved OS and PFS with 20 mg/kg vs 12 mg/kg A479.

Conclusions: Increased exposure to A479 is associated with improved clinical outcomes in mPC. This supports the evaluation of 20 mg/kg A479 in P3.

[Table: see text]