Antimicrobial peptides (AMPs) constitute promising alternatives to classical antibiotics for the treatment of drug-resistant infections, which are a rapidly emerging global health challenge. However, our understanding of the structure-function relationships of AMPs is limited, and we are just beginning to rationally engineer peptides in order to develop them as therapeutics. Here, we leverage a physicochemical-guided peptide design strategy to identify specific functional hotspots in the wasp-derived AMP polybia-CP and turn this toxic peptide into a viable antimicrobial. Helical fraction, hydrophobicity, and hydrophobic moment are identified as key structural and physicochemical determinants of antimicrobial activity, utilized in combination with rational engineering to generate synthetic AMPs with therapeutic activity in a mouse model. We demonstrate that, by tuning these physicochemical parameters, it is possible to design nontoxic synthetic peptides with enhanced sub-micromolar antimicrobial potency in vitro and anti-infective activity in vivo. We present a physicochemical-guided rational design strategy to generate peptide antibiotics.

Physiologic changes during development, aging, and pregnancy may affect clinical parameters. Previously available reference values have been based on samples that may include wild and captive marmosets, with little representation of geriatricor pregnant animals. Establishing reference values under various conditions would support better recognition of pathologic conditions in marmosets. One hundred and forty-seven (70 males and 77 females) healthy marmosets from a research colony were included in this study. Exclusion criteria were abnormal physical exam findings at the time of blood sampling, chronicmedications, or clinical or pathologic evidence of disease. Reference intervals were calculated for serum chemistry andhematology. Using metadata, samples were classified based on age, sex, colony source and pregnancy status. Multiple testsindicated significant differences with varying effect sizes, indicating that developing reference intervals based on metadatacan be useful. Across all the comparisons, medium or large effect sizes were observed most frequently in blood urea nitrogen (BUN), calcium, total protein, alkaline phosphatase (ALP), weight and serum albumin. We report normative clinical pathologic data for captive common marmosets through all life stages and reproductive status. Significant differences were observed in most parameters when stratifying data based on age, sex, colony source, or pregnancy, suggesting that developing reference intervals considering this information is important for clinicians.

Purpose Although gemcitabine is a mainstay of pancreatic cancer therapy, it is only moderately effective, and it would be desirable to measure drug uptake in patients. 1-(2′-deoxy-2′-fluoroarabinofuranosyl) cytosine (FAC), is an analog of gemcitabine, and when labeled with F-18, it may be a potential surrogate PET tracer for the drug. Procedures [18F]FAC was synthesized to a radiochemical purity of >96 %. The human tumor lines AsPC1, BxPC3, Capan-1, Panc1, and MiaPaca2 were grown orthotopically in nude mice. KPC mice that conditionally express oncogenic K-ras and p53 mutations in pancreatic tissue were also used. The intra-tumoral distributions of [14C]gemcitabine and [18F]FAC were mapped with autoradiography. The inter-tumor correlation between [14C]gemcitabine and [18F]FAC was established in the orthotopic tumors. Expression of the equilibrative and concentrative nucleoside transporters (ENT, CNT) in vitro was detected by western blotting. Drug uptake was characterized in vitro using [3H]gemcitabine and the effect of transporter inhibition on gemcitabine and FAC uptake was investigated. The relative affinity of cells for gemcitabine and FAC was tested in competition assays. The cell lines differed in sensitivity to transport inhibitors and in competition studies. There was a good in vivo correlation between the total uptake of [18F]FAC and [14C]gemcitabine, measured across all orthotopic tumors. Using the KPC and BxPC3 models, we found that [14C]gemcitabine and [18F]FAC were largely co-localized. Conclusions In the lines examined here, [18F]FAC uptake correlates well with gemcitabine in vivo, supporting the notion that [18F]FAC can serve as a PET radiotracer surrogate to determine the uptake and distribution of gemcitabine within pancreatic tumors.

Purpose To evaluate the feasibility of delivering experimental radiotherapy to tumors in the mouse pancreas. Imaging and treatment were performed using combined CT (computed tomography)/orthovoltage treatment with a rotating gantry. Methods and Materials After intraperitoneal administration of radiopaque iodinated contrast, abdominal organ delineation was performed by X-ray CT. With this technique we delineated the pancreas, and both orthotopic xenografts and genetically engineered disease. CT imaging was validated by comparison with magnetic resonance (MR) imaging. Therapeutic radiation was delivered via a 1 cm diameter field. Selective X-ray radiation therapy (XRT) of the non-invasively defined orthotopic mass was confirmed using γH2AX staining. Mice could tolerate a dose of 15 Gy when the field was centered on the pancreas tail, and treatment was delivered as a continuous 360-degree arc. This strategy was then used for radiation therapy planning for selective delivery of therapeutic XRT to orthotopic tumors. Results Tumor growth delay after 15 Gy was monitored, using CT and ultrasound to determine the tumor volume at various times post-treatment. Our strategy enables the use of clinical radiation oncology approaches to treat experimental tumors in the pancreas of small animals for the first time. We demonstrate that delivery of 15 Gy from a rotating gantry minimizes background healthy tissue damage and significantly retards tumor growth. Conclusions This advance permits evaluation of radiation planning and dosing parameters. Accurate non-invasive longitudinal imaging and monitoring of tumor progression and therapeutic response in pre-clinical models is now possible, and can be expected to more effectively evaluate pancreatic cancer disease and therapeutic response.