Hell's Itch: A Unique Reaction to UV Exposure

We present a survey-based exploration of Hell's Itch, a severe dermatologic reaction often mistaken for sunburn, that reveals distinct symptoms including intense pain, unrelenting itching, paresthesia, and even suicidal ideation, differentiating it from a typical sunburn.

The Correlation of Sleep Disturbance and Location of Glioma Tumors: A Narrative Review

Sleep disturbance can occur when sleep centers of the brain, regions that are responsible for coordinating and generating healthy amounts of sleep, are disrupted by glioma growth or surgical resection. Several disorders cause disruptions to the average duration, quality, or patterns of sleep, resulting in sleep disturbance. It is unknown whether specific sleep disorders can be reliably correlated with glioma growth, but there are sufficient numbers of case reports to suggest that a connection is possible. In this manuscript, these case reports and retrospective chart reviews are considered in the context of the current primary literature on sleep disturbance and glioma diagnosis to identify a new and useful connection which warrants further systematic and scientific examination in preclinical animal models. Confirmation of the relationship between disruption of the sleep centers in the brain and glioma location could have significant implications for diagnostics, treatment, monitoring of metastasis/recurrence, and end-of-life considerations.

Moving beyond Titers

Vaccination to prevent and even eliminate disease is amongst the greatest achievements of modern medicine. Opportunities remain in vaccine development to improve protection across the whole population. A next step in vaccine development is the detailed molecular characterization of individual humoral immune responses against a pathogen, especially the rapidly evolving pathogens. New technologies such as sequencing the immune repertoire in response to disease, immunogenomics/vaccinomics, particularly the individual HLA variants, and high-throughput epitope characterization offer new insights into disease protection. Here, we highlight the emerging technologies that could be used to identify variation within the human population, facilitate vaccine discovery, improve vaccine safety and efficacy, and identify mechanisms of generating immunological memory. In today’s vaccine-hesitant climate, these techniques used individually or especially together have the potential to improve vaccine effectiveness and safety and thus vaccine uptake rates. We highlight the importance of using these techniques in combination to understand the humoral immune response as a whole after vaccination to move beyond neutralizing titers as the standard for immunogenicity and vaccine efficacy, especially in clinical trials.

The next frontier of oncotherapy: accomplishing clinical translation of oncolytic bacteria through genetic engineering

The development of a 'smart' drug capable of distinguishing tumor from host cells has been sought for centuries, but the microenvironment of solid tumors continues to confound therapeutics. Solid tumors present several challenges for current oncotherapeutics, including aberrant vascularization, hypoxia, necrosis, abnormally high pH and local immune suppression. While traditional chemotherapeutics are limited by such an environment, oncolytic microbes are drawn to it - having an innate ability to selectively infect, colonize and eradicate solid tumors. Development of an oncolytic species would represent a shift in the cancer therapeutic paradigm, with ramifications reaching from the medical into the socio-economic. Modern genetic engineering techniques could be implemented to customize 'Frankenstein' bacteria with advantageous characteristics from several species.

Epitope characterization of anti-drug antibodies-a tool for discovery and health: an overview of the necessity of early epitope characterization to avoid anti-drug antibodies and promote patient health

Introduction: The market for monoclonal antibody (mAb) therapies is growing rapidly as the pharmaceutical industry expands its development across a broad spectrum of diseases. Unfortunately, as shown in the recent failure of bococizumab by Pfizer, these treatments often stimulate the formation of problematic anti-drug antibodies (ADAs). ADAs can cause side effects and limit efficacy for many patients. To increase efficacy and decrease safety concerns from ADAs, immunogenicity characterization is needed early in the drug development process. Here, we present emerging techniques that hold promise to improve ADA assays and their potential applications to pharmaceutical development and personalized medicine.Areas covered: This manuscript outlines the importance of epitope characterization to better understand immunogenicity and describes a strategy for using this information in treating patients taking mAb therapies.Expert opinion: We propose using high-information assays to characterize epitopes to help mAb therapy engineering and potentially improve individual patient outcomes. To understand this, we will discuss three different aspects of ADAs: (1) the problem of ADAs and what is currently being done about them, (2) the current state of epitope characterization and how it is being utilized, and (3) how early epitope characterization can advance drug discovery and improve outcomes for patients taking mAb therapies.

Dynamics of a Viscous Droplet in Return Bends of Microfluidic Channels

Return bends are frequently encountered in microfluidic systems. In this study, a three-dimensional spectral boundary element method for interfacial dynamics in Stokes flow has been adopted to investigate the dynamics of viscous droplets in rectangular return bends. The droplet trajectory, deformation, and migration velocity are investigated under the influence of various fluid properties and operational conditions, which are depicted by the Capillary number, viscosity ratio, and droplet size, as well as the dimensions of the return bend. While the computational results provide information for the design of return bends in microfluidic systems in general, the computational framework shows potential to guide the design and operation of a droplet-based microfluidic delivery system for cell seeding.

Characterizing Epitope Binding Regions of Entire Antibody Panels by Combining Experimental and Computational Analysis of Antibody: Antigen Binding Competition

Vaccines and immunotherapies depend on the ability of antibodies to sensitively and specifically recognize particular antigens and specific epitopes on those antigens. As such, detailed characterization of antibody-antigen binding provides important information to guide development. Due to the time and expense required, high-resolution structural characterization techniques are typically used sparingly and late in a development process. Here, we show that antibody-antigen binding can be characterized early in a process for whole panels of antibodies by combining experimental and computational analyses of competition between monoclonal antibodies for binding to an antigen. Experimental "epitope binning" of monoclonal antibodies uses high-throughput surface plasmon resonance to reveal which antibodies compete, while a new complementary computational analysis that we call "dock binning" evaluates antibody-antigen docking models to identify why and where they might compete, in terms of possible binding sites on the antigen. Experimental and computational characterization of the identified antigenic hotspots then enables the refinement of the competitors and their associated epitope binding regions on the antigen. While not performed at atomic resolution, this approach allows for the group-level identification of functionally related monoclonal antibodies (i.e., communities) and identification of their general binding regions on the antigen. By leveraging extensive epitope characterization data that can be readily generated both experimentally and computationally, researchers can gain broad insights into the basis for antibody-antigen recognition in wide-ranging vaccine and immunotherapy discovery and development programs.

Vaccine-induced antibodies to herpes simplex virus glycoprotein D epitopes involved in virus entry and cell-to-cell spread correlate with protection against genital disease in guinea pigs

Herpes simplex virus type 2 (HSV-2) glycoprotein D (gD2) subunit antigen is included in many preclinical candidate vaccines. The rationale for including gD2 is to produce antibodies that block crucial gD2 epitopes involved in virus entry and cell-to-cell spread. HSV-2 gD2 was the only antigen in the Herpevac Trial for Women that protected against HSV-1 genital infection but not HSV-2. In that trial, a correlation was detected between gD2 ELISA titers and protection against HSV-1, supporting the importance of antibodies. A possible explanation for the lack of protection against HSV-2 was that HSV-2 neutralization titers were low, four-fold lower than to HSV-1. Here, we evaluated neutralization titers and epitope-specific antibody responses to crucial gD2 epitopes involved in virus entry and cell-to-cell spread as correlates of immune protection against genital lesions in immunized guinea pigs. We detected a strong correlation between neutralizing antibodies and protection against genital disease. We used a high throughput biosensor competition assay to measure epitope-specific responses to seven crucial gD2 linear and conformational epitopes involved in virus entry and spread. Some animals produced antibodies to most crucial epitopes while others produced antibodies to few. The number of epitopes recognized by guinea pig immune serum correlated with protection against genital lesions. We confirmed the importance of antibodies to each crucial epitope using monoclonal antibody passive transfer that improved survival and reduced genital disease in mice after HSV-2 genital challenge. We re-evaluated our prior study of epitope-specific antibody responses in women in the Herpevac Trial. Humans produced antibodies that blocked significantly fewer crucial gD2 epitopes than guinea pigs, and antibody responses in humans to some linear epitopes were virtually absent. Neutralizing antibody titers and epitope-specific antibody responses are important immune parameters to evaluate in future Phase I/II prophylactic human vaccine trials that contain gD2 antigen.

Using hydrodynamic focusing to predictably alter the diameter of synthetic silk fibers

Spiders and silkworms provide a model of superior processing for multifunctional and highly versatile high-performance fibers. Mimicking the spider's complex control system for chemical and mechanical gradients has remained an ongoing obstacle for synthetic silk production. In this study, the use of hydrodynamic fluid focusing within a 3D printed biomimetic spinning system to recapitulate the biological spinneret is explored and shown to produce predictable, small diameter fibers. Mirroring in silico fluid flow simulations using a hydrodynamic microfluidic spinning technique, we have developed a model correlating spinning rates, solution viscosity and fiber diameter outputs that will significantly advance the field of synthetic silk fiber production. The use of hydrodynamic focusing to produce controlled output fiber diameter simulates the natural silk spinning process and continues to build upon a 3D printed biomimetic spinning platform.

The Complex Relationship between Virulence and Antibiotic Resistance

Antibiotic resistance, prompted by the overuse of antimicrobial agents, may arise from a variety of mechanisms, particularly horizontal gene transfer of virulence and antibiotic resistance genes, which is often facilitated by biofilm formation. The importance of phenotypic changes seen in a biofilm, which lead to genotypic alterations, cannot be overstated. Irrespective of if the biofilm is single microbe or polymicrobial, bacteria, protected within a biofilm from the external environment, communicate through signal transduction pathways (e.g., quorum sensing or two-component systems), leading to global changes in gene expression, enhancing virulence, and expediting the acquisition of antibiotic resistance. Thus, one must examine a genetic change in virulence and resistance not only in the context of the biofilm but also as inextricably linked pathologies. Observationally, it is clear that increased virulence and the advent of antibiotic resistance often arise almost simultaneously; however, their genetic connection has been relatively ignored. Although the complexities of genetic regulation in a multispecies community may obscure a causative relationship, uncovering key genetic interactions between virulence and resistance in biofilm bacteria is essential to identifying new druggable targets, ultimately providing a drug discovery and development pathway to improve treatment options for chronic and recurring infection.

Prostate-Specific Membrane Antigen Targeted Polymersomes for Delivering Mocetinostat and Docetaxel to Prostate Cancer Cell Spheroids

Prostate cancer cells overexpress the prostate-specific membrane antigen (PSMA) receptors on the surface. Targeting the PSMA receptor creates a unique opportunity for drug delivery. Docetaxel is a Food and Drug Administration-approved drug for treating metastatic and androgen-independent prostate cancer, and mocetinostat is a potent inhibitor of class I histone deacetylases. In this study, we prepared reduction-sensitive polymersomes presenting folic acid on the surface and encapsulating either docetaxel or mocetinostat. The presence of folic acid allowed efficient targeting of the PSMA receptor and subsequent internalization of the polymeric vesicles in cultured LNCaP prostate cancer cell spheroids. The intracellular reducing agents efficiently released docetaxel and mocetinostat from the polymersomes. The combination of the two drug-encapsulated polymersome formulations significantly (p < 0.05) decreased the viability of the LNCaP cells (compared to free drugs or control) in three-dimensional spheroid cultures. The calculated combination index value indicated a synergistic effect for the combination of mocetinostat and docetaxel. Thus, our PSMA-targeted drug-encapsulated polymersomes has the potential to lead to a new direction in prostate cancer therapy that decreases the toxicity and increases the efficacy of the drug delivery systems.

An Osteoconductive Antibiotic Bone Eluting Putty with a Custom Polymer Matrix

With the rising tide of antibiotic resistant bacteria, extending the longevity of the current antibiotic arsenal is becoming a necessity. Developing local, controlled release antibiotic strategies, particularly for difficult to penetrate tissues such as bone, may prove to be a better alternative. Previous efforts to develop an osteoconductive local antibiotic release device for bone were created as solid molded composites; however, intimate contact with host bone was found to be critical to support host bone regrowth; thus, an osteocondconductive antibiotic releasing bone void filling putty was developed. Furthermore, a controlled releasing polymer matrix was refined using pendant-functionalized diols to provide tailorable pharmacokinetics. In vitro pharmacokinetic and bioactivity profiles were compared for a putty formulation with an analogous composition as its molded counterpart as well as four new pendant-functionalized polymers. A best-fit analysis of polymer composition in either small cylindrical disks or larger spheres revealed that the new pendant-functionalized polymers appear to release vancomycin via both diffusion and erosion regardless of the geometry of the putty. In silico simulations, a valuable technique for diffusion mediated controlled release models, will be used to confirm and optimize this property.

Polymer-controlled release of tobramycin from bone graft void filler

Despite clinical, material, and pharmaceutical advances, infection remains a major obstacle in total joint revision surgery. Successful solutions must extend beyond bulk biomaterial and device modifications, integrating locally delivered pharmaceuticals and physiological cues at the implant site, or within large bone defects with prominent avascular spaces. One approach involves coating clinically familiar allograft bone with an antibiotic-releasing rate-controlling polymer membrane for use as a matrix for local drug release in bone. The kinetics of drug release from this system can be tailored via alterations in the substrate or the polymeric coating. Drug-loaded polycaprolactone coating releases bioactive tobramycin from both cadaveric-sourced cancellous allograft fragments and synthetic hybrid coralline ceramic bone graft fragments with similar kinetics over a clinically relevant 6-week timeframe. However, micron-sized allograft particulate provides extended bioactive tobramycin release. Addition of porogen polyethylene glycol to the polymer coating formulation changes tobramycin release kinetics without significant impact on released antibiotic bioactivity. Incorporation of oil-microencapsulated tobramycin into the polymer coating did not significantly modify tobramycin release kinetics. In addition to releasing inhibitory concentrations of tobramycin, antibiotic-loaded allograft bone provides recognized beneficial osteoconductive potential, attractive for decreasing orthopedic surgical infections with improved filling of dead space and new bone formation.

A critical comparison of protein microarray fabrication technologies

Of the diverse analytical tools used in proteomics, protein microarrays possess the greatest potential for providing fundamental information on protein, ligand, analyte, receptor, and antibody affinity-based interactions, binding partners and high-throughput analysis. Microarrays have been used to develop tools for drug screening, disease diagnosis, biochemical pathway mapping, protein-protein interaction analysis, vaccine development, enzyme-substrate profiling, and immuno-profiling. While the promise of the technology is intriguing, it is yet to be realized. Many challenges remain to be addressed to allow these methods to meet technical and research expectations, provide reliable assay answers, and to reliably diversify their capabilities. Critical issues include: (1) inconsistent printed microspot morphologies and uniformities, (2) low signal-to-noise ratios due to factors such as complex surface capture protocols, contamination, and static or no-flow mass transport conditions, (3) inconsistent quantification of captured signal due to spot uniformity issues, (4) non-optimal protocol conditions such as pH, temperature, drying that promote variability in assay kinetics, and lastly (5) poor protein (e.g., antibody) printing, storage, or shelf-life compatibility with common microarray assay fabrication methods, directly related to microarray protocols. Conventional printing approaches, including contact (e.g., quill and solid pin), non-contact (e.g., piezo and inkjet), microfluidics-based, microstamping, lithography, and cell-free protein expression microarrays, have all been used with varying degrees of success with figures of merit often defined arbitrarily without comparisons to standards, or analytical or fiduciary controls. Many microarray performance reports use bench top analyte preparations lacking real-world relevance, akin to "fishing in a barrel", for proof of concept and determinations of figures of merit. This review critiques current protein-based microarray preparation techniques commonly used for analytical and function-based proteomics and their effects on array-based assay performance.

A resorbable antibiotic-eluting polymer composite bone void filler for perioperative infection prevention in a rabbit radial defect model

Nearly 1.3 million total joint replacement procedures are performed in the United States annually, with numbers projected to rise exponentially in the coming decades. Although finite infection rates for these procedures remain consistently low, device-related infections represent a significant cause of implant failure, requiring secondary or revision procedures. Revision procedures manifest several-fold higher infection recurrence rates. Importantly, many revision surgeries, infected or not, require bone void fillers to support the host bone and provide a sufficient tissue bed for new hardware placement. Antibiotic-eluting bone void fillers (ABVF), providing both osteoconductive and antimicrobial properties, represent one approach for reducing rates of orthopedic device-related infections. Using a solvent-free, molten-cast process, a polymer-controlled antibiotic-eluting calcium carbonate hydroxyapatite (HAP) ceramic composite BVF (ABVF) was fabricated, characterized, and evaluated in vivo using a bacterial challenge in a rabbit radial defect window model. ABVF loaded with tobramycin eliminated the infectious burden in rabbits challenged with a clinically relevant strain of Staphylococcus aureus (inoculum as high as 10⁷ CFU). Histological, microbiological, and radiographic methods were used to detail the effects of ABVF on microbial challenge to host bone after 8 weeks in vivo. In contrast to the HAP/BVF controls, which provided no antibiotic protection and required euthanasia 3 weeks post-operatively, tobramycin-releasing ABVF animals showed no signs of infection (clinical, microbiological, or radiographic) when euthanized at the 8-week study endpoint. ABVF sites did exhibit fibrous encapsulation around the implant at 8 weeks. Local antibiotic release from ABVF to orthopedic sites requiring bone void fillers eliminated the periprosthetic bacterial challenge in this 8-week in vivo study, confirming previous in vitro results.

The importance of epitope binning for biological drug discovery

The pharmaceutical industry is experiencing comeback sales growth due in large part to the industry’s R&D efforts that center on biologics drug development. To facilitate that effort, tools are being developed for more effective biologic drug development. At the forefront of this effort is epitope characterization, in particular epitope binning, primarily due to the role an epitope plays in drug function. Here we detail the financial advantages of epitope binning including (1) increased R&D productivity due to increased work in process, (2) reduced number of “dead-end”candidates, and (3) increasedability to reengineer antibodies based on the epitope. With the arrival of high throughput biosensors, this manuscript serves as a call to push epitope binning earlier in the biological drug discovery process.

Optimal tube length for the submerged printing of ovarian cancer cells

Ovarian cancer is the fifth most common cancer affecting US women, killing more women each year than all other gynecologic cancers combined. Treatment of ovarian cancer is challenging with an overall 5-year survival rates of only 28-46% based on the metastatic state of the disease. While overall survival has improved with modern chemotherapy, poor outcomes have persisted. One of the greatest challenges in cancer therapeutic research remains that late-stage drug development trials for drug candidates have high attrition rates, up to 70% in Phase II and 59% in Phase III trials. The development of in vitro, high-throughput, cell based assays could provide a tool to overcome the challenges associated with high attrition rates by allowing for controlled cell deposition with a defined, controlled phenotype. Submerged, three-dimensional (3D) microfluidic printing technology is uniquely capable of controlling cell deposition without sacrificing the viability of cells for cell-based assays. Here, we investigate the phenotypic effects of tube length during printing on the cells. We observe that the length of the tube has minimal effects on the viability and density of A2780 ovarian cancer cells different cell lines. This study details foundational information for developing a high-throughput cell-based assays (CBA) for screening effective cancer drug candidates.

Comparison of submerged and unsubmerged printing of ovarian cancer cells

A high-throughput cell based assay would greatly aid in the development and screening of ovarian cancer drug candidates. Previously, a three-dimensional microfluidic printer that is not only capable of controlling the location of cell deposition, but also of maintaining a liquid, nutrient rich environment to preserve cellular phenotype has been developed (Wasatch Microfluidics). In this study, we investigated the impact (i.e., viability, density, and phenotype) of depositing cells on a surface submerged in cell culture media. It was determined that submersion of the microfluidic print head in cell media did not alter the cell density, viability, or phenotype.. This article describes an in depth study detailing the impact of one of the fundamental components of a 3D microfluidic cell printer designed to mimic the in vivo cell environment. Development of such a tool holds promise as a high-throughput drug-screening platform for new cancer therapeutics.

LPS modification promotes maintenance of Yersinia pestis in fleas

Yersinia pestis, the causative agent of plague, can be transmitted by fleas by two different mechanisms: by early-phase transmission (EPT), which occurs shortly after flea infection, or by blocked fleas following long-term infection. Efficient flea-borne transmission is predicated upon the ability of Y. pestis to be maintained within the flea. Signature-tagged mutagenesis (STM) was used to identify genes required for Y. pestis maintenance in a genuine plague vector, Xenopsylla cheopis. The STM screen identified seven mutants that displayed markedly reduced fitness in fleas after 4 days, the time during which EPT occurs. Two of the mutants contained insertions in genes encoding glucose 1-phosphate uridylyltransferase (galU) and UDP-4-amino-4-deoxy-l-arabinose-oxoglutarate aminotransferase (arnB), which are involved in the modification of lipid A with 4-amino-4-deoxy-l-arabinose (Ara4N) and resistance to cationic antimicrobial peptides (CAMPs). These Y. pestis mutants were more susceptible to the CAMPs cecropin A and polymyxin B, and produced lipid A lacking Ara4N modifications. Surprisingly, an in-frame deletion of arnB retained modest levels of CAMP resistance and Ara4N modification, indicating the presence of compensatory factors. It was determined that WecE, an aminotransferase involved in biosynthesis of enterobacterial common antigen, plays a novel role in Y. pestis Ara4N modification by partially offsetting the loss of arnB. These results indicated that mechanisms of Ara4N modification of lipid A are more complex than previously thought, and these modifications, as well as several factors yet to be elucidated, play an important role in early survival and transmission of Y. pestis in the flea vector.

Therapeutic strategies to combat antibiotic resistance

With multidrug resistant bacteria on the rise, new antibiotic approaches are required. Although a number of new small molecule antibiotics are currently in the development pipeline with many more in preclinical development, the clinical options and practices for infection control must be expanded. Biologics and non-antibiotic adjuvants offer this opportunity for expansion. Nevertheless, to avoid known mechanisms of resistance, intelligent combination approaches for multiple simultaneous and complimentary therapies must be designed. Combination approaches should extend beyond biologically active molecules to include smart controlled delivery strategies. Infection control must integrate antimicrobial stewardship, new antibiotic molecules, biologics, and delivery strategies into effective combination therapies designed to 1) fight the infection, 2) avoid resistance, and 3) protect the natural microbiome. This review explores these developing strategies in the context of circumventing current mechanisms of resistance.

The submerged printing of cells onto a modified surface using a continuous flow microspotter

The printing of cells for microarray applications possesses significant challenges including the problem of maintaining physiologically relevant cell phenotype after printing, poor organization and distribution of desired cells, and the inability to deliver drugs and/or nutrients to targeted areas in the array. Our 3D microfluidic printing technology is uniquely capable of sealing and printing arrays of cells onto submerged surfaces in an automated and multiplexed manner. The design of the microfluidic cell array (MFCA) 3D fluidics enables the printhead tip to be lowered into a liquid-filled well or dish and compressed against a surface to form a seal. The soft silicone tip of the printhead behaves like a gasket and is able to form a reversible seal by applying pressure or backing away. Other cells printing technologies such as pin or ink-jet printers are unable to print in submerged applications. Submerged surface printing is essential to maintain phenotypes of cells and to monitor these cells on a surface without disturbing the material surface characteristics. By printing onto submerged surfaces, cell microarrays are produced that allow for drug screening and cytotoxicity assessment in a multitude of areas including cancer, diabetes, inflammation, infections, and cardiovascular disease.

Polymer-controlled extended combination release of silver and chlorhexidine from a bone void filler

Although rates of total joint prosthetic infections remain relatively constant at 1-3%, an increasing number of orthopedic procedures and a corresponding rise in the absolute number of infectious complications mandate distinctly new solutions. In order to combat the implant infection threat, an antibiotic-releasing bone void filler (BVF), commercial tradename, ElutiBone™, has been developed using a combination of commercially available ceramic-based BVF plus clinically familiar biocompatible polymers, and a variety of select, dispersed antibiotics. While several traditional antibiotics have been successfully released for an extended duration, a more versatile strategy, releasing multiple antibiotics simultaneously, may be possible. In this study, the antiseptic chlorhexidine and a variety of bacteriostatic silver compounds were incorporated to provide synergistic antimicrobial activity upon release in combination formulations from ElutiBone matrices. Silver chloride was the most effective bacteriostatic tested (p=0.05), showing a measurable zone of inhibition at spiked concentrations as low as 31µg/ml. Subsequently, silver chloride was used in combination with the antiseptic chlorhexidine to test for enhanced antimicrobial bioactivity against S. aureus. Measurable synergy between the two compounds confirmed the suitability of ElutiBone™ to locally deliver this multidrug antimicrobial cocktail. A myriad of other drug interactions could and should be tested in this novel system in order to expand the utility and combat the increasing prevalence of polymicrobial infections.

Molded polymer-coated composite bone void filler improves tobramycin controlled release kinetics

Infection remains a significant problem associated with biomedical implants and orthopedic surgeries, especially in revision total joint replacements. Recent advances in antibiotic-releasing bone void fillers (BVF) provide new opportunities to address these types of device-related orthopedic infections that often lead to substantial economic burdens and reduced quality of life. We report improvements made in fabrication and scalability of an antibiotic-releasing polycaprolactone-calcium carbonate/phosphate ceramic composite BVF using a new solvent-free, molten-cast fabrication process. This strategy provides the ability to tailor drug release kinetics from the BVF composite based on modifications of the inorganic substrate and/or the polymeric component, allowing extended tobramycin release at bactericidal concentrations. The mechanical properties of the new BVF composite are comparable to many reported BVFs and validate the relative homogeneity of fabrication. Most importantly, fabrication quality controls are correlated with favorable drug release kinetics, providing bactericidal activity to 10 weeks in vitro when the polycaprolactone component exceeds 98% w/w of the total polymer fraction. Furthermore, in a time kill study, tobramycin-releasing composite fragments inhibited S. aureus growth over 48 h at inoculums as high as 10(9) CFU/mL. This customizable antibiotic-releasing BVF polymer-inorganic biomaterial should provide osseointegrative and osteoconductive properties while contributing antimicrobial protection to orthopedic sites requiring the use of bone void fillers.

A comparison of the potential for acute cardiopulmonary adverse effects in dogs during continuous veno-venous hemofiltration with accusol 35 solution with and without induced calcium carbonate particles

BACKGROUND

Baxter received reports of visible precipitate, identified as calcium carbonate, forming during hemofiltration with Accusol 35 solution.

AIM

To evaluate the potential for acute cardiopulmonary adverse effects of Accusol 35 containing exaggerated calcium carbonate particles.

METHODS

Anesthetized dogs underwent continuous veno-venous hemofiltration (CVVH) with Accusol 35 containing visible and subvisible particles (≥10 µm) 36 times higher than the maximum concentration specified in the European Pharmacopoeia (P-Accusol), or Accusol 35 conforming to specification (Accusol). Select cardiovascular and blood gas parameters were evaluated during CVVH. Lung tissue samples were collected following CVVH.

RESULTS

No differences were observed in cardiovascular and blood gas parameters or lung histology between P-Accusol and Accusol.

CONCLUSION

Accusol 35 containing visible and subvisible particles (≥10 µm) 36 times higher than the maximum concentration specified in the European Pharmacopoeia resulted in no acute cardiopulmonary adverse effects compared with Accusol 35 containing no visible particles and subvisible particles within European Pharmacopoeia specification.

Cationic PAMAM dendrimers aggressively initiate blood clot formation

Poly(amidoamine) (PAMAM) dendrimers are increasingly studied as model nanoparticles for a variety of biomedical applications, notably in systemic administrations. However, with respect to blood-contacting applications, amine-terminated dendrimers have recently been shown to activate platelets and cause a fatal, disseminated intravascular coagulation (DIC)-like condition in mice and rats. We here demonstrate that, upon addition to blood, cationic G7 PAMAM dendrimers induce fibrinogen aggregation, which may contribute to the in vivo DIC-like phenomenon. We demonstrate that amine-terminated dendrimers act directly on fibrinogen in a thrombin-independent manner to generate dense, high-molecular-weight fibrinogen aggregates with minimal fibrin fibril formation. In addition, we hypothesize this clot-like behavior is likely mediated by electrostatic interactions between the densely charged cationic dendrimer surface and negatively charged fibrinogen domains. Interestingly, cationic dendrimers also induced aggregation of albumin, suggesting that many negatively charged blood proteins may be affected by cationic dendrimers. To investigate this further, zebrafish embryos were employed to more specifically determine the speed of this phenomenon and the pathway- and dose-dependency of the resulting vascular occlusion phenotype. These novel findings show that G7 PAMAM dendrimers significantly and adversely impact many blood components to produce rapid coagulation and strongly suggest that these effects are independent of classic coagulation mechanisms. These results also strongly suggest the need to fully characterize amine-terminated PAMAM dendrimers in regard to their adverse effects on both coagulation and platelets, which may contribute to blood toxicity.

An inexpensive system for evaluating the tussive and anti-tussive properties of chemicals in conscious, unrestrained guinea pigs

INTRODUCTION

Commercial whole-body plethysmography systems used to evaluate the anti-tussive potential of drugs employ sophisticated technology, but these systems may be cost prohibitive for some laboratories. The present study describes an alternative, inexpensive system for evaluating the tussive and anti-tussive potential of drugs in conscious, unrestrained guinea pigs.

METHODS

The system is composed of a transparent small animal anesthesia induction box fitted with a microphone, a camera and a pneumotachometer to simultaneously capture audio, video, air flow and air pressure in real time. Data acquisition and analysis was performed using free software for audio and video, and a research pneumotach system for flow and pressure. System suitability testing was performed by exposing conscious, unrestrained guinea pigs to nebulized aqueous solutions of a selective agonist for TRPV1 (citric acid) or a selective agonist for TRPA1 (AITC), with or without pre-treatment with a selective antagonist for TRPV1 (BCTC) or a selective antagonist for TRPA1 (HC-030031).

RESULTS

The system easily discerned coughs from other respiratory events like sneezes. System suitability test results are as follows: AITC caused 10.7 (SEM=1.4592) coughs vs. 5.8 (SEM=1.6553) when pre-treated with HC-030031 (P<0.05). Citric acid caused 12.4 (SEM=1.4697) coughs vs. 3.2 (SEM=1.3928) when pre-treated with BCTC (P<0.002).

DISCUSSION

We have described in detail an inexpensive system for evaluating the tussive and anti-tussive potential of chemicals in conscious, unrestrained guinea pigs. Suitability testing indicates that the system is comparable to a commercial whole-body plethysmography system for detecting and differentiating between coughs and sneezes. This system may provide some investigators a cost-conscious alternative to more expensive commercial whole-body plethysmography systems.

Cationic PAMAM dendrimers disrupt key platelet functions

Poly(amidoamine) (PAMAM) dendrimers have been proposed for a variety of biomedical applications and are increasingly studied as model nanomaterials for such use. The dendritic structure features both modular synthetic control of molecular size and shape and presentation of multiple equivalent terminal groups. These properties make PAMAM dendrimers highly functionalizable, versatile single-molecule nanoparticles with a high degree of consistency and low polydispersity. Recent nanotoxicological studies showed that intravenous administration of amine-terminated PAMAM dendrimers to mice was lethal, causing a disseminated intravascular coagulation-like condition. To elucidate the mechanisms underlying this coagulopathy, in vitro assessments of platelet functions in contact with PAMAM dendrimers were undertaken. This study demonstrates that cationic G7 PAMAM dendrimers activate platelets and dramatically alter their morphology. These changes to platelet morphology and activation state substantially altered platelet function, including increased aggregation and adherence to surfaces. Surprisingly, dendrimer exposure also attenuated platelet-dependent thrombin generation, indicating that not all platelet functions remained intact. These findings provide additional insight into PAMAM dendrimer effects on blood components and underscore the necessity for further research on the effects and mechanisms of PAMAM-specific and general nanoparticle toxicity in blood.

PD06-05: Primary and Secondary Pegfilgrastim Utilization in Adjuvant Chemotherapy for Breast Cancer in the Community

Background

Various factors are taken into consideration in the selection of adjuvant breast cancer (BC) chemotherapy (CT) regimens for patients. Choice of CT, schedule, duration, and supportive care affects costs and toxicity. Understanding clinical practice utilization patterns are important when making cost estimates of adjuvant therapy. Because pegfilgrastim is a large driver of cost it is important to understand the utilization characteristics. We aimed to characterize primary and secondary pegfilgrastim use during neoadjuvant/adjuvant (N/Ad) chemotherapy by regimen type. While initial data suggests the incidence of febrile neutropenia (FN) is low among some docetaxel containing regimens, we wanted to further characterize pegfilgrastim utilization, as previous utilization studies suggested it was higher than expected.

Methods: Using the US Oncology iKnowMed™ EHR database, we retrospectively identified female BC patients (pts) diagnosed with stage I-III BC, between 7/2006 and 11/2010. Secondary diagnoses were excluded. Pts were characterized by age, ER and HER2 status, tumor size, grade, and nodes. CT utilization was determined by the number of pts assigned an N/Ad line of therapy (LOT) during the study period. Regimens were categorized by CT title and drugs. Clinical trial pts were included. Pegfilgrastim utilization was characterized if administered within 6 months of being assigned to an N/Ad CT regimen, and was captured as primary prophylaxis if the first dose was administered &lt;5 days of C1D1 of a regimen, and secondary prophylaxis if &gt;5days.

Results: General chemotherapy and pegfilgrastim utilization characteristics were previously reported. This report captures primary vs. secondary pegfilgrastim use. During the time period, 40,881 BC pts were identified. Of these, 15,328 pts (37%) were assigned an N/Ad CT regimen and 72% (11, 022 pts) received pegfilgrastim at any time within 6 months of their N/Ad regimen. Docetaxel containing regimens (TC, TAC, TCH) and dose-dense regimens accounted for the majority of all pegfilgrastim use. Pegfilgrastim utilization with the TC regimen was 70%, and represented 25% of all N/Ad pegfilgrastim utilization. The vast majority of utilization for TC and TCH was primary prophylaxis as detailed below:

Evaluating antibiotic release profiles as a function of polymer coating formulation - biomed 2011

To address persistent 1-3% infection rates associated with orthopedic implant surgeries, the next generation of bone graft filler materials will no longer pharmacologically silent being endowed as a local drug delivery vehicle to maintain locally high levels of antibiotic. Bone allograft material, used as a structural support to fill the avascular spaces in bone defects, revision surgeries, and traumatic injury, can be used as a drug depot to provide effective antibiotic delivery over the orthopedically relevant six-to-eight week time period. Passive antibiotic coatings, applied in the surgical theater, are quickly depleted from the site, inadvertently promoting the development of drug-resistance. Alternatively, many promising controlled-delivery strategies provide an initial burst release of antibiotic within 24 to 72 hours; however, this remains inadequate to combat the onslaught of ubiquitous pathogens that can persist only to reemerge once drug concentrations fall below the minimal inhibitory concentration (MIC). To improve the longevity of this strategy, a variety of coating techniques were evaluated in which clinically-accepted, FDA-recognized, degradable polycaprolactone (PCL) polymer acts as a rate-controlling membrane to retard the release of the antibiotic tobramycin from allograft bone. Using a combination of dipping and rapid drying, the drug-releasing polymer coating was applied concurrently maintaining the high surface area of the allograft bone; however, SEM imaging reveled an imperfect coating that negatively affected the release kinetics. Altering the drug-containing polymer formulation to incorporate water provided a smoother, more uniform coat and ultimately improved the drug-release profile and longevity out to 5 weeks using both bacteriostatic and bacteriocidal assays. Additionally, drug bioactivity was assessed and confirmed between 2 and 4 weeks in the absence of the water-containing polymer.

Analyzing the clustering effects of major ampullate silk mechanical properties - biomed 2009

Although spider silk displays an amazing combination of strength and extensibility unrivalled by most synthetic biomaterials, its molecular architecture is relatively simplistic. Four primary amino acid block motifs (An, (GA)n, GPGXX, GGX) have been correlated with mechanical functions. Recent genetic engineering to control the mechanical behavior of synthetic silk fibers has verified much of the proposed structure/function relationship; however, the genetically defined exchange between strength and elasticity has proven not to be a direct relationship. Thus, complete control over the mechanical properties of a synthetic spider silk based fiber continues to elude scientists. The yet undefined factor(s) may be an element of the fabrication process. Natural silk production results from a combination of dehydration and protein alignment that occurs during concurrent spin and draw processes. While synthetic fiber production attempts to mimic 1) dehydration with a series of coagulating solvents and 2) protein alignment through the controlled extrusion of a concentration dependent spinning solution, the spinning and drawing processes are separated and occur sequentially. Many studies have been conducted which have examined multiple parameters; however, the spinning conditions which produce consistent mechanical properties, necessary for the progression toward any medical, commercial or military application, have not been identified. Here, we report on mathematical methods based on data from a variety of spinning conditions to characterize different impacting properties as either primary (i.e. a condition which directs or dictates mechanical properties of an individual fiber) or ptimizing (i.e. a condition which increases the engineered properties of the silk).

Distribution and function of enteric GAL-IR nerves in dogs: comparison with VIP

The distribution of nerves containing galanin-immunoreactive (GAL-IR) material was compared to the distribution of neurons containing vasoactive intestinal polypeptide (VIP) immunoreactivity in the canine gastrointestinal tract. The actions of intra-arterially administered galanin and VIP on motility in the gastric antrum and corpus and the intestines were also studied. All sphincter muscles contained galanin- and VIP-immunoreactive nerve profiles. VIP-immunoreactive nerve profiles were present in all layers of the stomach, small intestine, and colon. GAL-IR nerve somata were common in the submucous plexus of ileum and colon and in the myenteric plexus of the terminal antrum, as were nerve processes in various layers. In the small intestine, galanin inhibited contractile responses to field stimulation of intrinsic nerves and also reduced the contractions after nerve blockade with tetrodotoxin (TTX). VIP often enhanced field-stimulated contractions at low doses but inhibited these and the contractions after TTX at higher doses. In the stomach and colon, both peptides inhibited responses to field stimulation; whether these effects were due to actions on smooth muscle was not tested. The distribution and actions of galanin in gut are consistent with the hypothesis that it acts at smooth muscle sites and possibly at prejunctional sites.

Phase I trial of adjuvant chemotherapy with cyclophosphamide, epirubicin and 5-fluorouracil (CEF) for stage II breast cancer

Epirubicin is a new anthracycline with a potentially more favorable toxicity profile than the parent compound, doxorubicin. Accordingly, the feasibility and toxicity of 6 courses of adjuvant chemotherapy with cyclophosphamide (C), epirubicin (E), and 5-fluorouracil (F) were assessed in 10 patients with Stage 2 (node positive) breast cancer. Doses of C and F were 600 mg/m2 and E was 75 mg/m2. Moderate granulocytopenia (median count = 610/mm3) occurred on day 14 of the first 21 day treatment course and was the main toxicity encountered with treatment, although there were no episodes of granulocytopenic fever. Grade 3 or 4 vomiting occurred in 40% and significant alopecia in 30% of patients. Four patients experienced transient asymptomatic decreases in calculated radionuclide cardiac ejection fraction of greater than or equal to 10% but no signs or symptoms of cardiac failure were observed. If epirubicin proves to be less cardiotoxic than doxorubicin, this combination would merit further evaluation as potential adjuvant therapy for early breast cancer.

Characterization of content and chromatographic forms of neuropeptides in purified nerve varicosities prepared from guinea pig myenteric plexus

Partially purified nerve varicosities (PV) prepared from guinea pig ileal myenteric plexus were found to contain, by radioimmunoassay, gastrin-releasing polypeptide (GRP), substance P (SP), galanin, Leu-enkephalin (LE), Met-enkephalin (ME), and vasoactive intestinal polypeptide (VIP). SP was present in the highest concentration followed by, in descending order, ME, LE, VIP, GRP and galanin. On reverse-phase HPLC, SP-, LE- and ME-like immunoreactivity in the PV preparation eluted at retention times similar to their synthetic analogues, galanin-like immunoreactivity eluted at a retention time different from that of synthetic porcine galanin and VIP-like immunoreactivity eluted at the retention time of synthetic guinea pig VIP. GRP-like immunoreactivity, on reverse-phase HPLC, eluted at retention times close to that of synthetic porcine GRP-(1-27) and its major oxidized form. Evidence was obtained for the presence of an alpha-neurokinin-like immunoreactive entity and an unidentified SP-like immunoreactive entity in guinea pig myenteric plexus.