Peter Qiao

High Fat Diet Feeding Exaggerates Perfluorooctanoic Acid-Induced Liver Injury in Mice via Modulating Multiple Metabolic Pathways

High fat diet (HFD) is closely linked to a variety of health issues including fatty liver. Exposure to perfluorooctanoic acid (PFOA), a synthetic perfluorinated carboxylic acid, also causes liver injury. The present study investigated the possible interactions between high fat diet and PFOA in induction of liver injury. Mice were pair-fed a high-fat diet (HFD) or low fat control with or without PFOA administration at 5 mg/kg/day for 3 weeks. Exposure to PFOA alone caused elevated plasma alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels and increased liver weight along with reduced body weight and adipose tissue mass. HFD alone did not cause liver damage, but exaggerated PFOA-induced hepatotoxicity as indicated by higher plasma ALT and AST levels, and more severe pathological changes including hepatocyte hypertrophy, lipid droplet accumulation and necrosis as well as inflammatory cell infiltration. These additive effects of HFD on PFOA-induced hepatotoxicity correlated with metabolic disturbance in liver and blood as well as up-regulation of hepatic proinflammatory cytokine genes. Metabolomic analysis demonstrated that both serum and hepatic metabolite profiles of PFOA, HFD, or HFD-PFOA group were clearly differentiated from that of controls. PFOA affected more hepatic metabolites than HFD, but HFD showed positive interaction with PFOA on fatty acid metabolites including long chain fatty acids and acylcarnitines. Taken together, dietary high fat potentiates PFOA-induced hepatic lipid accumulation, inflammation and necrotic cell death by disturbing hepatic metabolism and inducing inflammation. This study demonstrated, for the first time, that HFD increases the risk of PFOA in induction of hepatotoxicity.

A novel chitosan-hydrogel-based nanoparticle delivery system for local inner ear application.

Hypothesis A chitosan-hydrogel-based nanoparticle (nanohydrogel) delivery system can be used to deliver therapeutic biomaterials across the round window membrane (RWM) into the inner ear in a mouse model. Background Delivering therapies to the inner ear has always been a challenge for the otolaryngologist. Advances in biomedical nanotechnology, increased understanding of the RWM diffusion properties, and discovery of novel therapeutic targets and agents, have all sparked interest in the controlled local delivery of drugs and biomaterials to the inner ear using nanoparticles (NPs). Methods Fluorescently-labeled liposomal NPs were constructed and loaded into a chitosan-based hydrogel to form a nanohydrogel, and in vitro studies were performed to evaluate its properties and release kinetics. Furthermore, the nanohydrogel was applied to the RWM of mice, and perilymph and morphologic analysis were performed to assess the NP delivery and distribution within the inner ear. Results NPs with an average diameter of 160 nm were obtained. In vitro experiments showed that liposomal NPs can persist under physiologic conditions for at least two weeks without significant degradation and that the nanohydrogel can carry and release these NPs in a controlled and sustained manner. In vivo findings demonstrated that the nanohydrogel can deliver intact nanoparticles into the perilymphatic system and reach cellular structures in the scala media of the inner ear of our mouse model. Conclusion Our study suggests that the nanohydrogel system has great potential to deliver therapeutics in a controlled and sustained manner from the middle ear to the inner ear without altering inner ear structures.

Isolated human and animal stratum corneum as a partial model for the 15 steps of percutaneous absorption: emphasizing decontamination, part II

Cutaneously directed chemical warfare agents can elicit significant morbidity and mortality. The optimization of prophylactic and therapeutic interventions counteracting these agents is crucial, and the development of decontamination protocols and methodology of post dermal exposure risk assessments would be additionally applicable to common industrial and consumer dermatotoxicants. Percutaneous (PC) penetration is often considered a simple one‐step diffusion process but presently consists of at least 15 steps. The systemic exposure to an agent depends on multiple factors and the second part of this review covers absorption and excretion kinetics, wash and rub effects, skin substantivity and transfer, among others. Importantly, the partitioning behavior and diffusion through the stratum corneum (SC) of a wide physicochemical array of compounds shows that many compounds have approximately the same diffusion coefficient which determines their percutaneous absorption in vivo. After accounting for anatomical variation of the SC, the penetration flux value of a substance depends mainly on its SC/vehicle partition coefficient. Additionally, the SC acts as a ‘reservoir’ for topically applied molecules, and tape stripping methodology can quantify the remaining chemical in the SC which can predict the total molecular penetration in vivo. The determination of ideal decontamination protocols is of utmost importance to reduce morbidity and mortality. However, even expeditious standard washing procedures post dermal chemical exposure often fails to remove chemicals. The second part of this overview continues to review percutaneous penetration extending insights into the complexities of penetration, decontamination and potential newer assays that may be of practical importance. Copyright

Isolated human/animal stratum corneum as a partial model for 15 steps in percutaneous absorption: emphasizing decontamination, Part I: 15 steps in percutaneous absorption

Since the advent of World War II, governments and laboratories have made a concerted effort to improve prophylactic and therapeutic interventions counteracting cutaneously directed chemical warfare agents (CWA), and by inference, common industrial and consumer dermatotoxicants. In vitro percutaneous penetration assays, first utilized by Tregear in the 1940s and presently in various modifications, have been fundamental to this effort. Percutaneous penetration, often considered a simple one‐step diffusion process, consists of at least 15 steps. The first part of this review covers the initial steps related to absorption and excretion kinetics, vehicle characteristics, and tissue disposition. Importantly, the partitioning behavior and stratum corneum (SC) diffusion by a wide physicochemical array of compounds shows that many compounds have similar diffusion coefficients determining their percutaneous absorption in vivo. After accounting for anatomical SC variation, the penetration flux value of a substance depends mainly on its SC/vehicle partition coefficient. Additionally, the SC acts as a ‘reservoir’ for topically applied molecules and application of tape stripping has been found to quantify the chemical remaining in the SC which can predict total molecular penetration in vivo. Decontamination is of particular concern and even expediting standard washing procedures after dermal chemical exposure often fails to remove chemicals. This overview summarizes knowledge of percutaneous penetration extending insights into the complexities of penetration, decontamination and potential newer assays that may be of practical importance. Copyright

Dermal exposure to methamphetamine hydrochloride contaminated residential surfaces: surface pH values, volatility, and in vitro human skin.

This study evaluated pH effects on [(14)C] d-methamphetamine hydrochloride ([(14)C]-meth HCl) percutaneous penetration in vitro and volatility and stability in aqueous solution, on solid surface, or human skin using the finite dose technique and flow through diffusion cells. Results show that when the pH level exceeds 4 or 5, the nonvolatile [(14)C]-meth HCl salt becomes unstable, likely converting to its volatile freebase form. Additionally, contaminated smooth, dense surfaces retain and transfer more [(14)C]-meth HCl than those with rough, loose surfaces, especially under acidic conditions. Skin surface pH is a critical factor affecting the rate and magnitude of dermal absorption. [(14)C]-Meth HCl penetrates into and through the human cadaver skin quickly following exposure. [(14)C]-Meth HCl retained in the skin layer is released into the receptor fluid even if the contact material has been removed. Future exploration of decontaminant and removal procedure efficacies and their effect on dermal penetration of [(14)C]-meth HCl is recommended.

Dermal exposure to methamphetamine hydrochloride contaminated residential surfaces II. Skin surface contact and dermal transfer relationship.

This in vitro investigation evaluated [(14)C] - d-methamphetamine hydrochloride ([(14)C]-meth HCl) transfer from contaminated vinyl tile (non-porous and smooth) and upholstery fabric (rough and loose) to human skin. (14)C-Meth HCl transfer rate from vinyl to skin was rapid; a contact duration as brief as 15s resulted in measurable radioactivity in the skin and receptor fluid samples. In contrast, the transfer from fabric occurred more slowly: the amount of [(14)C]-meth HCl that was transferred from dry fabric after 2-h skin contact was one-fifth the amount transferred from vinyl after 5-min contact time. With moistened fabric, the transfer efficiency to skin after 2-h contact was seven times greater than that of dry fabric. While the duration of surface-skin contact appeared to affect the total dermal absorption of [(14)C]-meth HCl, it had little effect on the time point of maximum transdermal absorption. [(14)C]-meth HCl retained in skin continued to be absorbed after the contaminated material was removed. Mass balance in these studies was approximately 96%. In conclusion, [(14)C]-meth HCl penetrates into/through human skin quickly following skin contact with contaminated materials. The porosity of the contact surface and the moisture content appears to alter the degree of transfer and dermal penetration.

Engineering Escherichia coli for Light-Activated Cytolysis of Mammalian Cells

By delivering payloads in response to specific exogenous stimuli, smart bacterial therapeutics have the potential to overcome many limitations of conventional therapies, including poor targeting specificity and dosage control in current cancer treatments. Although not yet explored as a trigger for bacterial drug delivery, light is an ideal induction mechanism because it offers fine spatiotemporal control and is easily and safely administered. Using recent advances in optogenetics, we have engineered two strains of Escherichia coli to secrete a potent mammalian cytotoxin in response to blue or red light. The tools in this study demonstrate the initial feasibility of light-activated bacterial therapeutics for applications such as tumor cytolysis, and their modular nature should enable simple substitution of other payloads of interest.

A Novel Regulated Nanohydrogel Delivery System for Inner Ear Application

Objectives: 1) Develop a novel chitosan-hydrogel-based nanoparticle delivery system (nanohydrogel) for inner ear application and to evaluate its structures and release kinetics in vitro. 2) Evaluate if the nanohydrogel delivery system can be turned off using an enzymatic regulator for inner ear delivery. 3) Evaluate the inner ear distribution of nanoparticles following round window membrane application in a mouse model. Methods: Nanoparticles labeled with fluorescence were constructed and loaded into a chitosan-based hydrogel to form a nanohydrogel delivery system. In vitro studies were performed to evaluate the thermosensitivity, structure, and nanoparticle release kinetics of the nanohydrogel with/without chitosanase enzymatic regulation. Morphologic studies were performed to evaluate the nanoparticle delivery and distribution within the inner ear structures in a mouse model. Results: After obtaining a homogeneous, viscous and thermosensitive nanohydrogel system, in vitro studies showed that the nanohydrogel can carry and release nanoparticles in a controlled and sustained manner, and chitosanase can effectively regulate this release if needed. A matrix-like ultrastructure containing nanosized particles was confirmed. In vivo findings further confirm that the nanohydrogel delivered nanoparticles into the perilymphatic system and reached cellular structures of the inner ear in our mouse model. Conclusions: Our study suggests that the nanohydrogel system has the potential to safely deliver drugs or biomaterials in a controlled and sustained manner for inner ear application. This system could be used for targeted therapy for inner ear diseases that require safe and non-invasive delivery approaches.

Inhibition of Novel Cetuximab Resistance Pathway Leads to Improved Outcomes in Head and Neck Cancer

Objectives: 1) Determine if cetuximab resistance in head and neck squamous cell carcinoma (HNSCC) is regulated by increased nuclear translocation of Epidermal Growth Factor Receptor (EGFR) through an MRN-dependent Akt phosphorylation pathway. 2) Determine if targeted inhibition of the MRN complex, a key mediator of DNA damage response, can improve cetuximab sensitivity in HNSCC. Methods: Two well-characterized human HNSCC tumor cell lines, with differential resistance to cetuximab, were chosen for this study. Mirin, a novel molecular MRN inhibitor was used for this study. MTT and clonogenic assays were used to evaluate in vitro cytotoxicity. Western blot analysis was performed to evaluate protein expression. In vivo tumor growth was evaluated using molecular imaging. Results: As compared with sensitive cells, cetuximab resistant cells demonstrated increased MRN expression, increased Akt phosphorylation, and increased nuclear EGFR. The inhibition of MRN led to a dose-dependent decrease in Akt phosphorylation and nuclear EGFR translocation. Furthermore, MRN inhibition synergistically enhanced the cytotoxic effect of cetuximab in resistant cells (P < 0.01). Conclusions: The findings from this study suggest a novel cetuximab resistance pathway involving MRN-mediated Akt phosphorylation, leading to increased nuclear translocation of EGFR. Furthermore, inhibition of MRN led to decreased Akt-phosphorylation, subsequently decreasing nuclear EGFR translocation, a key molecular mechanism involved in cetuximab resistance. Based on this discovery, inhibition of this pathway may serve as an effective therapeutic approach for HNSCC patients resistant to cetuximab.