Use of multimodality imaging, histology, and treatment feasibility to characterize a transgenic Rag2-null rat model of glioblastoma.

Many drugs that show potential in animal models of glioblastoma (GBM) fail to translate to the clinic, contributing to a paucity of new therapeutic options. In addition, animal model development often includes histologic assessment, but multiparametric/multimodality imaging is rarely included despite increasing utilization in patient cancer management. This study developed an intracranial recurrent, drug-resistant, human-derived glioblastoma tumor in Sprague-Dawley Rag2-Rag2 tm1Hera knockout rat and was characterized both histologically and using multiparametric/multimodality neuroimaging. Hybrid 18F-fluoroethyltyrosine positron emission tomography and magnetic resonance imaging, including chemical exchange saturation transfer (18F-FET PET/CEST MRI), was performed for full tumor viability determination and characterization. Histological analysis demonstrated human-like GBM features of the intracranially implanted tumor, with rapid tumor cell proliferation (Ki67 positivity: 30.5 ± 7.8%) and neovascular heterogeneity (von Willebrand factor VIII:1.8 to 5.0% positivity). Early serial MRI followed by simultaneous 18F-FET PET/CEST MRI demonstrated consistent, predictable tumor growth, with exponential tumor growth most evident between days 35 and 49 post-implantation. In a second, larger cohort of rats, 18F-FET PET/CEST MRI was performed in mature tumors (day 49 post-implantation) for biomarker determination, followed by evaluation of single and combination therapy as part of the model development and validation. The mean percentage of the injected dose per mL of 18F-FET PET correlated with the mean %CEST (r = 0.67, P < 0.05), but there was also a qualitative difference in hot spot location within the tumor, indicating complementary information regarding the tumor cell demand for amino acids and tumor intracellular mobile phase protein levels. Finally, the use of this glioblastoma animal model for therapy assessment was validated by its increased overall survival after treatment with combination therapy (temozolomide and idasanutlin) (P < 0.001). Our findings hold promise for a more accurate tumor viability determination and novel therapy assessment in vivo in a recently developed, reproducible, intracranial, PDX GBM.

Novel therapeutics and drug-delivery approaches in the modulation of glioblastoma stem cell resistance.

Glioblastoma (GBM) is a deadly malignancy with a poor prognosis. An important factor contributing to GBM recurrence is high resistance of GBM cancer stem cells (GSCs). While temozolomide (TMZ), has been shown to consistently extend survival, GSCs grow resistant to TMZ through upregulation of DNA damage repair mechanisms and avoidance of apoptosis. Since a single-drug approach has failed to significantly alter prognosis in the past 15 years, unique approaches such as multidrug combination therapy together with distinctive targeted drug-delivery approaches against cancer stem cells are needed. In this review, a rationale for multidrug therapy using a targeted nanotechnology approach that preferentially target GSCs is proposed with discussion and examples of drugs, nanomedicine delivery systems, and targeting moieties.

Development of CD133 Targeting Multi-Drug Polymer Micellar Nanoparticles for Glioblastoma - In Vitro Evaluation in Glioblastoma Stem Cells.

PURPOSE: Glioblastoma (GBM) is a malignant brain tumor with a poor long-term prognosis due to recurrence from highly resistant GBM cancer stem cells (CSCs), for which the current standard of treatment with temozolomide (TMZ) alone will unlikely produce a viable cure. In addition, CSCs regenerate rapidly and overexpress methyl transferase which overrides the DNA-alkylating mechanism of TMZ, leading to resistance. The objective of this research was to apply the concepts of nanotechnology to develop a multi-drug therapy, TMZ and idasanutlin (RG7388, a potent mouse double minute 2 (MDM2) antagonist), loaded in functionalized nanoparticles (NPs) that target the GBM CSC subpopulation, reduce the cell viability and provide possibility of in vivo preclinical imaging. METHODS: Polymer-micellar NPs composed of poly(styrene-b-ethylene oxide) (PS-b-PEO) and poly(lactic-co-glycolic) acid (PLGA) were developed by a double emulsion technique loading TMZ and/or RG7388. The NPs were covalently bound to a 15-nucleotide base-pair CD133 aptamer to target the CD133 antigen expressed on the surfaces of GBM CSCs. For diagnostic functionality, the NPs were labelled with radiotracer Zirconium-89 (89Zr). RESULTS: NPs maintained size range less than 100 nm, a low negative charge and exhibited the ability to target and kill the CSC subpopulation when TMZ and RG7388 were used in combination. The targeting function of CD133 aptamer promoted killing in GBM CSCs providing impetus for further development of targeted nanosystems for localized therapy in future in vivo models. CONCLUSIONS: This work has provided a potential clinical application for targeting GBM CSCs with simultaneous diagnostic imaging.

Aerosolized In Vivo 3D Localization of Nose-to-Brain Nanocarrier Delivery Using Multimodality Neuroimaging in a Rat Model-Protocol Development.

The fate of intranasal aerosolized radiolabeled polymeric micellar nanoparticles (LPNPs) was tracked with positron emission tomography/computer tomography (PET/CT) imaging in a rat model to measure nose-to-brain delivery. A quantitative temporal and spatial testing protocol for new radio-nanotheranostic agents was sought in vivo. LPNPs labeled with a zirconium 89 (89Zr) PET tracer were administered via intranasal or intravenous delivery, followed by serial PET/CT imaging. After 2 h of continuous imaging, the animals were sacrificed, and the brain substructures (olfactory bulb, forebrain, and brainstem) were isolated. The activity in each brain region was measured for comparison with the corresponding PET/CT region of interest via activity measurements. Serial imaging of the LPNPs (100 nm PLA-PEG-DSPE+89Zr) delivered intranasally via nasal tubing demonstrated increased activity in the brain after 1 and 2 h following intranasal drug delivery (INDD) compared to intravenous administration, which correlated with ex vivo gamma counting and autoradiography. Although assessment of delivery from nose to brain is a promising approach, the technology has several limitations that require further development. An experimental protocol for aerosolized intranasal delivery is presented herein, which may provide a platform for better targeting the olfactory epithelium.

Polymeric micelles for anticancer drug delivery.

Polymeric micelles have gained interest as novel drug delivery systems for the treatment and diagnosis of cancer, as they offer several advantages over conventional drug therapies. This includes drug targeting to tumor tissue, in vivo biocompatibility and biodegradability, prolonged circulation time, enhanced accumulation, retention of the drug loaded micelle in the tumor and decreased side effects. This article provides an overview on the current state of micellar formulations as nanocarriers for anticancer drugs and their effectiveness in cancer therapeutics, including their clinical status. The type of copolymers used, their physicochemical properties and characterization as well as recent developments in the design of functional polymeric micelles are highlighted. The article also presents the design and outcomes of various types of stimuli-responsive polymeric micelles.

Effect of methotrexate conjugated PAMAM dendrimers on the viability of MES-SA uterine cancer cells.

The aim of this work was to synthesize methotrexate (MTX)-polyamidoamine (PAMAM) dendritic nanoconjugates and to study their effect on cell viability in uterine sarcoma cells. The amide-bonded PAMAM dendrimer-MTX conjugates were prepared by conjugation between the amine-terminated G5 dendrimer and the carboxylic groups of the MTX using a dicyclohexylcarbodiimide coupling reaction. The formation of conjugates was evaluated by ultraviolet (UV) and (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy studies. The cell survival of MES-SA cells, a uterine sarcoma cell line, was evaluated in the presence of the dendrimer-MTX nanoconjugate, using appropriate controls. The UV and (1)H NMR study confirmed the formation of covalent bonds between the drug and the dendrimer. The cell viability study indicated that the nanoconjugates had significantly improved cell killing compared to the free MTX.

Recent Trends in Detection of Huntingtin and Preclinical Models of Huntington's Disease.

Huntington's disease is a genetically inherited neurodegenerative disease that is characterized by neuronal cell death in the brain. Molecular biology techniques to detect and quantify huntingtin protein in biological samples involve fluorescence imaging, western blotting, and PCR. Modified cell lines are widely used as models for Huntington's disease for preclinical screening of drugs to study their ability to suppress the expression of huntingtin. Although worm and fly species have been experimented on as models for Huntington's disease, the most successful animal models have been reported to be primates. This review critically analyses the molecular biology techniques for detection and quantitation of huntingtin and evaluates the various animal species for use as models for Huntington's disease.

RNAi-based therapies for Huntington's disease: delivery challenges and opportunities.

Huntington's disease (HD) is a polyglutamine neurodegenerative disease caused by a mutation in the HTT gene coding for the Huntingtin protein (HTT). Unfortunately, there is no cure for HD and there is also no known way to modify the disease progression. RNAi approaches offer the promise of a certain degree of control over the disease. However, there are several challenges in potential use of RNAi in the treatment of HD. This article will discuss the details of RNAi technology as applied to the treatment of HD, and novel approaches to overcome the drug delivery challenges.

Designing Paclitaxel drug delivery systems aimed at improved patient outcomes: current status and challenges.

Paclitaxel is one of the most widely used and effective antineoplastic agents derived from natural sources. It has a wide spectrum of antitumor activity, particularly against ovarian cancer, breast cancer, nonsmall cell lung cancer, head and neck tumors, Kaposi's sarcoma, and urologic malignancies. It is a highly lipophilic compound with a log P value of 3.96 and very poor aqueous solubility of less than 0.01 mg/mL. In addition, the compound lacks functional groups that are ionizable which could potentially lead to an increase in its solubility with the alteration in pH. Therefore, the delivery of paclitaxel is associated with substantial challenges. Until the introduction of Abraxane, only commercial formulation was solution of paclitaxel in cremophor, which caused severe side effects. However, in recent years, a number of approaches have been reported to solubilize paclitaxel using cosolvents and inclusion complexes. In addition, innovative approaches have been reported for passive targeting of tumors using nanoparticles, nanosuspensions, liposomes, emulsions, micelles, implants, pastes and gels. All approaches for delivery of improved therapeutic outcome have been discussed in this paper.

Paraganglioma of the oropharynx.

Paraganglioma is a rare tumor in head and neck region. A 35 years male presented with huge swelling of tonsillar region occupying a large portion of oropharynx. Tumor had been dissected out transorally. HPE showed extra-adrenal paraganglioma. It is being reported because of its rare clinical presentation and unusual surgical approach.

Effect of microfluidization parameters on the physical properties of PEG-PLGA nanoparticles prepared using high pressure microfluidization.

The objective of this work was to develop uniformly distributed poly(ethylene glycol) grafted poly(lactide-co-glycolide) (PEG-PLGA) nanoparticles of mean size range approximately 100-200 nm using ethyl acetate as the solvent. In the multiple emulsion solvent evaporation method a high pressure microfluidization process was adopted to produce the W/O/W multiple emulsion. Non-toxic ethyl acetate was used to solubilize PEG-PLGA. The mean size of nanoparticles obtained was less than 180 nm. The particle size and size distribution were dependent on the microfluidization conditions applied. Mean particle size steadily increased from 121 nm at three passes to 172 nm at 20 passes of the microfluidizer, indicating that over-processing may be detrimental to PEG-PLGA nanoparticles prepared using this technique. There was no significant alteration of the PEG-PLGA matrix, as evidenced from the differential scanning calorimetric studies.

Barriers to scholarship in dentistry, medicine, nursing, and pharmacy practice faculty.

There has been an increased emphasis on scholarly activities by health sciences faculty members given the importance of the promotion of public health over the last 50 years. Consequently, faculty members are required to place greater emphasis on scholarly activities while maintaining their teaching and service responsibilities. This increasing requirement of scholarly activities has placed great demands on clinical practice faculty members and it has made their management of clinical practice, teaching responsibilities, and expectations for promotion and tenure a difficult task. This retrospective literature review identifies barriers to the scholarship activities of clinical faculty members in dentistry, medicine, nursing, and pharmacy and discusses strategies for enabling faculty members to pursue scholarly activities in the current health science academic environment. The review indicates commonalities of barriers across these 4 disciplines and suggests strategies that could be implemented by all of these disciplines to enable clinical practice faculty members to pursue scholarly activities.

Effect of excipient and processing variables on adhesive properties and release profile of pentoxifylline from mucoadhesive tablets.

The bioavailability and onset of action of drugs with high first-pass metabolism can be significantly improved by administration via the sublingual route. The objective of this study was to evaluate the effect of polymer type and tablet compaction parameters on the adhesive properties and drug release profile from mucoadhesive sublingual tablet formulations. Pentoxifylline was selected as the model drug because it has poor oral bioavailability due to extensive first-pass metabolism. Two polymers known to possess mucoadhesive properties, carbomer and hydroxypropyl methyl cellulose (HPMC), were used to prepare the formulations. Tablets were prepared by using direct compression technique and evaluated for in vitro dissolution, drug-excipient interactions, and adhesive properties. In general, there was a decrease in the rate of drug release with an increase in the concentration of polymers. No drug-excipient interactions were evident from differential scanning calorimetry or high-performance liquid chromatography analysis. For the formulations containing HPMC, the force of mucoadhesion increased with an increase in the concentration of polymer; however, for carbomer formulations, no such correlation was observed. Force of mucoadhesion decreased as a function of hydration time in both of the polymers.

Bronchoprotection with formoterol via dry powder and metered-dose inhalers in patients with asthma.

BACKGROUND: Determination of device comparability for new inhaled medications is essential. OBJECTIVE: To evaluate the methacholine bronchoprotection afforded by formoterol, 12 microg, delivered via Clickhaler and Aerolizer dry powder inhalers and a pressurized metered-dose inhaler (pMDI) in mild-to-moderate asthmatic patients. METHODS: Two separate randomized, double-blind, double-dummy, crossover studies were performed. Peak bronchoprotection (30 minutes) was measured after administration of a single dose in a placebo-controlled study (n = 16). First-dose (8 hours) and trough (12 hours) protection were evaluated after 2 weeks (n = 28). Doubling dilution differences (DDD) in the methacholine provocation concentration that caused a decrease in forced expiratory volume in 1 second of 20% from baseline were compared, with equivalence defined if the 95% confidence interval was within the predefined equivalence limits of +/- 1.5 DDD (peak) and +/- 1.0 DDD (trough). RESULTS: For peak single-dose effects, DDD (95% confidence interval) data showed significant protection vs placebo for all devices but no significant differences among active inhalers. For trough first-dose effects, there was significant protection vs baseline for all devices and equivalence for Clickhaler vs Aerolizer (-0.41; -0.85 to 0.04) and Aerolizer vs pMDI (-0.27; -0.66 to 0.13) but not for Clickhaler vs pMDI (-0.68; -1.12 to -0.23). For trough effects after 2 weeks, there was significant residual protection from baseline and equivalence for Clickhaler vs Aerolizer (-0.32; -0.94 to 0.30), Clickhaler vs pMDI (0.34; -0.96 to 0.27), and Aerolizer vs pMDI (-0.02; -0.57 to 0.52). CONCLUSIONS: Formoterol delivered by 3 different inhalers exhibited a significant degree of peak and trough bronchoprotection after single and repeated dosing, with most comparisons being within predefined equivalence limits.

Dose-response comparison of budesonide dry powder inhalers using adenosine monophosphate bronchial challenge.

BACKGROUND: Bronchial hyperresponsiveness to adenosine monophosphate, an indirect measure of airway inflammation, is a sensitive marker of inhaled corticosteroid efficacy. OBJECTIVE: To evaluate the relative therapeutic efficacy of budesonide delivered via Clickhaler and Turbuhaler dry powder inhalers in patients with mild-to-moderate persistent asthma. METHODS: In a double-masked, dose-response crossover study, 27 patients received inhaled budesonide in cumulative sequential doubling dose increments, 2 weeks per dose, of 200, 400, and 800 microg/d. Each treatment block was preceded by 1- to 3-week placebo run-in and washout periods. End points were measured after each placebo (ie, baseline) and treatment period. Adenosine monophosphate bronchial challenge was the primary outcome, and exhaled nitric oxide, serum eosinophilic cationic protein, spirometry, domiciliary peak expiratory flow, symptoms, and rescue medication use were the secondary outcomes. RESULTS: For the adenosine monophosphate provocation concentration that caused a decrease in forced expiratory volume in 1 second of 20% (PC20), a significant overall dose-response effect (P = .006) was found, and there was no significant difference between the devices (P = .8). The relative microgram dose potency ratio between Clickhaler and Turbuhaler was 1.11 (95% confidence interval [CI], 0.50-2.46). After administration of the highest dose of budesonide, the mean doubling dilution shift in adenosine monophosphate PC20 from placebo baseline was 3.46 (95% CI, 2.66-4.27) with the Clickhaler vs 3.41 (95% CI, 2.47-4.35) with the Turbuhaler. A significant overall dose-response effect was demonstrated for exhaled nitric oxide (P = .03) but not for any of the other secondary outcome measures. There were no significant differences between the devices for any of the outcome measures. CONCLUSION: Inhaled budesonide exhibited overall dose-response effects on adenosine monophosphate PC20 delivered via Turbuhaler and Clickhaler, with no significant difference between the devices.

Development of mucoadhesive dosage forms of buprenorphine for sublingual drug delivery.

The development of mucoadhesive formulations of buprenorphine for intended sublingual usage in the treatment of drug addiction is described. The formulations include mucoadhesive polymer films, with or without plasticizers, and mucoadhesive polymer tablets, with or without excipients that enhance drug release and/or improve tablet compaction properties. The mucoadhesive polymers studied include carbomers such as Carbopol 934P, Carbopol 974P, and the polycarbophil Noveon AA-1, with excipients chosen from pregelatinized starch, lactose, glycerol, propylene glycol, and various molecular weights of polyethylene glycol. The development of plasticizer-containing mucoadhesive polymer films was feasible; however, these films failed to release their entire drug content within a reasonable period. Thus, they were not determined suitable for sublingual usage because of possible loss by ingestion during routine meal intakes. The mucoadhesive strength of tablet formulations containing Noveon AA-1 appears to be slightly superior to the Carbopol-containing tablets. However, the Carbopol 974P formulations exhibited superior drug dissolution profiles while providing adequate mucoadhesive strength. The tablet formulations containing Carbopol 974P as mucoadhesive polymer, lactose as drug release enhancer, and PEG 3350 as compaction enhancer exhibited the best results. Overall, the mucoadhesive tablet formulations exhibited superior results compared with the mucoadhesive film formulations.