Evaluating Radioactive Analogs of Doxorubicin to Quantify ChemoFilter Binding and Whole-Body Positron Emission Tomography/Magnetic Resonance Imaging for Drug Biodistribution.

PURPOSE: To evaluate radiolabeled doxorubicin (Dox) analogs as tracers of baseline Dox biodistribution in vivo during hepatic intra-arterial chemotherapy and to assess the efficacy of ChemoFilter devices to bind Dox in vitro. MATERIALS AND METHODS: In an in vitro static experiment, [fluorine-18]N-succinimidyl 4-fluorobenzoate ([18F]SFB) and [fluorine-18]fluorobenzoyl-doxorubicin ([18F]FB-Dox) were added to a beaker containing a filter material (Dowex cation exchange resin, single-stranded DNA (ssDNA) resin, or sulfonated polymer coated mesh). In an in vitro flow model, [18F]FB-Dox was added into a Dox solution in phosphate-buffered saline, and the solution flowed via a syringe column containing the filter materials. In an in vitro flow experiment, using micro-positron emission tomography (PET), images were taken as [18F]SFB and [18F]FB-Dox moved through a phantom. For in vivo biodistribution testing, a catheter was placed into the common hepatic artery of a swine, and [18F]FB-Dox was infused over 30 seconds. A 10-minute dynamic image and three 20-minute static images were acquired using 3T PET/MR imaging. RESULTS: In the in vitro static experiment, [18F]FB-Dox demonstrated 76.7%, 88.0%, and 52.4% binding to the Dowex resin, ssDNA resin, and coated mesh, respectively. In the in vitro flow model, the first-pass binding of [18F]FB-Dox to the Dowex resin, ssDNA resin, and coated mesh was 76.7%, 74.2%, and 76.2%, respectively, and the total bound fraction was 80.9%, 84.6%, and 79.9%, respectively. In the in vitro flow experiment using micro-PET, the phantom demonstrated a greater amount of [18F]FB-Dox bound to both filter cartridges than of the control [18F]SFB. In in vivo biodistribution testing, the first 10 minutes depicted [18F]FB-Dox moving through the right upper quadrant of the abdomen. A region-of-interest analysis showed that the relative amount increased by 2.97 times in the gallbladder and 1.08 times in the kidney. The amount decreased by 0.74 times in the brain and 0.57 times in the heart. CONCLUSIONS: [18F]FB-Dox can be used to assess Dox binding to ChemoFilters as well as in vivo biodistribution. This sets the stage for the evaluation of ChemoFilter effectiveness in reducing systemic toxicity from intra-arterial chemotherapy.

Radiographic Outcomes Following the Suture Fixation of Mid-pole Patellar Fractures.

Background Mid-pole patellar fractures are typically fixed with metal implants in the conventional "11-8" tension band construct. However, this technique is fraught with numerous implant-related complications. The aim of this study is to evaluate the union rate following "all-suture" fixation of mid-pole patellar fractures. Methods We retrospectively evaluated a consecutive case series of patients with displaced mid-pole patella fractures treated with "all-suture" fixation in our institution. Fifteen cases were available for this study. The average age was 61.5 years. Clinical and radiological outcomes were evaluated. Union time, complications, and revision rate were recorded. The minimum follow-up was one year. Results There were eight males and seven females, with a mean age of 61.5 ± 13.3 years. Fourteen out of 15 cases (93.3%) achieved radiographic union at 12 weeks postoperatively. The average time to radiographic union was 8.0 ± 2.7 weeks. Five cases (33.3%) had an increase in the fracture gap (>2 mm) at around four to six weeks postoperatively. Four of these cases had an eventual union, whereas one patient had fibrous non-union. There was one case of superficial surgical site infection and one case of infected hematoma. None of the patients required revision surgery. Conclusion "All-suture" fixation of mid-pole transverse patellar fractures is a safe and viable alternative to the conventional "11-8" tension band constructs with metal implants, with good union time, rates, and added benefits of not requiring additional surgery for implant removal.

Wireless Resonant Circuits Printed Using Aerosol Jet Deposition for MRI Catheter Tracking.

Interventional magnetic resonance imaging (MRI) could allow for diagnosis and immediate treatment of ischemic stroke; however, such endovascular catheter-based procedures under MRI guidance are inherently difficult. One major challenge is tracking the tip of the catheter, as standard fabrication methods for building inductively coupled coil markers are rigid and bulky. Here, we report a new approach that uses aerosol jet deposition to three-dimensional (3-D) print an inductively coupled RF coil marker on a polymer catheter. Our approach enables lightweight conforming markers on polymer catheters and these low-profile markers allow the catheter to be more safely navigated in small caliber vessels. Prototype markers with an inductor with the geometry of a double helix are incorporated on catheters for in vitro studies, and we show that these markers exhibit good signal amplification. We report temperature measurements and, finally, demonstrate feasibility in a preliminary in vivo experiment. We provide material properties and electromagnetic simulation performance analysis. This paper presents fully aerosol jet-deposited and functional wireless resonant markers on polymer catheters for use in 3T clinical scanners.

3D Printed Absorber for Capturing Chemotherapy Drugs before They Spread through the Body.

Despite efforts to develop increasingly targeted and personalized cancer therapeutics, dosing of drugs in cancer chemotherapy is limited by systemic toxic side effects. We have designed, built, and deployed porous absorbers for capturing chemotherapy drugs from the bloodstream after these drugs have had their effect on a tumor, but before they are released into the body where they can cause hazardous side effects. The support structure of the absorbers was built using 3D printing technology. This structure was coated with a nanostructured block copolymer with outer blocks that anchor the polymer chains to the 3D printed support structure and a middle block that has an affinity for the drug. The middle block is polystyrenesulfonate which binds to doxorubicin, a widely used and effective chemotherapy drug with significant toxic side effects. The absorbers are designed for deployment during chemotherapy using minimally invasive image-guided endovascular surgical procedures. We show that the introduction of the absorbers into the blood of swine models enables the capture of 64 ± 6% of the administered drug (doxorubicin) without any immediate adverse effects. Problems related to blood clots, vein wall dissection, and other biocompatibility issues were not observed. This development represents a significant step forward in minimizing toxic side effects of chemotherapy.

Endovascular Ion Exchange Chemofiltration Device Reduces Off-Target Doxorubicin Exposure in a Hepatic Intra-arterial Chemotherapy Model.

Purpose: To determine if endovascular chemofiltration with an ionic device (ChemoFilter [CF]) can be used to reduce systemic exposure and off-target biodistribution of doxorubicin (DOX) during hepatic intra-arterial chemotherapy (IAC) in a preclinical model. Materials and Methods: Hepatic IAC infusions were performed in six pigs with normal livers. Animals underwent two 10-minute intra-arterial infusions of DOX (200 mg) into the common hepatic artery. Both the treatment group and the control group received initial IAC at 0 minutes and a second dose at 200 minutes. Prior to the second dose, CF devices were deployed in and adjacent to the hepatic venous outflow tract of treatment animals. Systemic exposure to DOX was monitored via blood samples taken during IAC procedures. After euthanasia, organ tissue DOX concentrations were analyzed. Alterations in systemic DOX exposure and biodistribution were compared by using one-tailed t tests. Results: CF devices were well tolerated, and no hemodynamic, thrombotic, or immunologic complications were observed. Animals treated with a CF device had a significant reduction in systemic exposure when compared with systemic exposure in the control group (P <.009). Treatment with a CF device caused a significant decrease in peak DOX concentration (31%, P <.01) and increased the time to maximum concentration (P <.03). Tissue analysis was used to confirm significant reduction in DOX accumulation in the heart and kidneys (P <.001 and P <.022, respectively). Mean tissue concentrations in the heart, kidneys, and liver of animals treated with CF compared with those in control animals were 14.2 µg/g ± 1.9 (standard deviation) versus 26.0 µg/g ± 1.8, 46.4 µg/g ± 4.6 versus 172.6 µg/g ± 40.2, and 217.0 µg/g ± 5.1 versus 236.8 µg/g ± 9.0, respectively. Fluorescence imaging was used to confirm in vivo DOX binding to CF devices. Conclusion: Reduced systemic exposure and heart bioaccumulation of DOX during local-regional chemotherapy to the liver can be achieved through in situ adsorption by minimally invasive image-guided CF devices.© RSNA, 2019.

Evaluating the impact of the multiplex respiratory virus panel polymerase chain reaction test on the clinical management of suspected respiratory viral infections in adult patients in a hospital setting.

A retrospective cohort design was used to study the impact of a multiplex respiratory virus panel polymerase chain reaction test in 186 adult patients with suspected influenza-like illness. Decisions regarding continuation of empirical antiviral therapy appear to be impacted by the test. However, the impact on reducing antibiotic use remains unclear.

Site specificity of DSP-PP cleavage by BMP1.

Bone morphogenic protein 1 (BMP1), a metalloproteinase, is known to cleave a wide variety of extracellular matrix proteins, suggesting that a consensus substrate cleavage amino acid sequence might exist. However, while such a consensus sequence has been proposed based on P4 to P4' (i.e. the four amino acids flanking either side of the BMP1 cleavage site; P4P3P2P1|P1'P2'P3'P4') sequence homologies between two BMP1 substrates, dentin matrix protein 1 and dentin sialoprotein phosphophoryn (DSP-PP) (i.e. xMQx|DDP), no direct testing has so far been attempted. Using an Sf9 cell expression system, we have been able to produce large amounts of uncleaved DSP-PP. Point mutations introduced into this recombinant DSP-PP were then tested for their effects on DSP-PP cleavage by either Sf9 endogenous tolloid-related protein 1 (TLR-1) or by its human homolog, BMP1. Here, we have measured DSP-PP cleavage efficiencies after modifications based on P4-P4' sequence comparisons with dentin matrix protein 1, as well as for prolysyl oxidase and chordin, two other BMP1 substrates. Our results demonstrate that any mutations within or outside of the DSP-PP P4 to P4' cleavage site can block, impair or accelerate DSP-PP cleavage, and suggest that its BMP1 cleavage site is highly conserved in order to regulate its cleavage efficiency, possibly with additional assistance from its conserved exosites. Thus, BMP1 cleavage cannot be based on a consensus substrate cleavage site.

The efficiency of dentin sialoprotein-phosphophoryn processing is affected by mutations both flanking and distant from the cleavage site.

Normal dentin mineralization requires two highly acidic proteins, dentin sialoprotein (DSP) and phosphophoryn (PP). DSP and PP are synthesized as part of a single secreted precursor, DSP-PP, which is conserved in marsupial and placental mammals. Using a baculovirus expression system, we previously found that DSP-PP is accurately cleaved into DSP and PP after secretion into medium by an endogenous, secreted, zinc-dependent Sf9 cell activity. Here we report that mutation of conserved residues near and distant from the G(447)↓D(448) cleavage site in DSP-PP(240) had dramatic effects on cleavage efficiency by the endogenous Sf9 cell processing enzyme. We found that: 1) mutation of residues flanking the cleavage site from P(4) to P(4)' blocked, impaired, or enhanced DSP-PP(240) cleavage; 2) certain conserved amino acids distant from the cleavage site were important for precursor cleavage; 3) modification of the C terminus by appending a C-terminal tag altered the pattern of processing; and 4) mutations in DSP-PP(240) had similar effects on cleavage by recombinant human BMP1, a candidate physiological processing enzyme, as was seen with the endogenous Sf9 cell activity. An analysis of a partial TLR1 cDNA from Sf9 cells indicates that residues that line the substrate-binding cleft of Sf9 TLR1 and human BMP1 are nearly perfectly conserved, offering an explanation of why Sf9 cells so accurately process mammalian DSP-PP. The fact that several mutations in DSP-PP(240) significantly modified the amount of PP(240) product generated from DSP-PP(240) precursor protein cleavage suggests that such mutation may affect the mineralization process.

DSP-PP precursor protein cleavage by tolloid-related-1 protein and by bone morphogenetic protein-1.

Dentin sialoprotein (DSP) and phosphophoryn (PP), acidic proteins critical to dentin mineralization, are translated from a single transcript as a DSP-PP precursor that undergoes specific proteolytic processing to generate DSP and PP. The cleavage mechanism continues to be controversial, in part because of the difficulty of obtaining DSP-PP from mammalian cells and dentin matrix. We have infected Sf9 cells with a recombinant baculovirus to produce large amounts of secreted DSP-PP(240), a variant form of rat DSP-PP. Mass spectrometric analysis shows that DSP-PP(240) secreted by Sf9 cells undergoes specific cleavage at the site predicted from the N-terminal sequence of PP extracted from dentin matrix: SMQG(447)↓D(448)DPN. DSP-PP(240) is cleaved after secretion by a zinc-dependent activity secreted by Sf9 cells, generating DSP(430) and PP(240) products that are stable in the medium. DSP-PP processing activity is constitutively secreted by Sf9 cells, but secretion is diminished 3 days after infection. Using primers corresponding to the highly conserved catalytic domain of Drosophila melanogaster tolloid (a mammalian BMP1 homolog), we isolated a partial cDNA for a Spodopotera frugiperda tolloid-related-1 protein (TLR1) that is 78% identical to Drosophila TLR1 but only 65% identical to Drosophila tolloid. Tlr1 mRNA decreased rapidly in Sf9 cells after baculovirus infection and was undetectable 4d after infection, paralleling the observed decrease in secretion of the DSP-PP(240) processing activity after infection. Human BMP1 is more similar to Sf9 and Drosophila TLR1 than to tolloid, and Sf9 TLR1 is more similar to BMP1 than to other mammalian homologs. Recombinant human BMP1 correctly processed baculovirus-expressed DSP-PP(240) in a dose-dependent manner. Together, these data suggest that the physiologically accurate cleavage of mammalian DSP-PP(240) in the Sf9 cell system represents the action of a conserved processing enzyme and support the proposed role of BMP1 in processing DSP-PP in dentin matrix.

Effect of leptin on vascular calcification in apolipoprotein E-deficient mice.

OBJECTIVE: The adipocytokine leptin has been proposed to increase cardiovascular risk in both obese and diabetic individuals. In the current study, therefore, we used apoE-deficient mice to examine the effects of leptin on both lesion size and calcification. METHODS AND RESULTS: Mice were treated with once daily intraperitoneal injections of leptin (125 microg/mouse/d) for 2 months. The mice were then euthanized, and sections of the aortic root and thoracic aorta analyzed histomorphometrically. Measurements of lesion size and surface area occupied by atherosclerotic lesions did not reveal any differences between nontreated and leptin-treated animals. However, von Kossa staining of the aortic root demonstrated an 8.3+/-2.0-fold increase in lesion calcification as well as a 2.5+/-0.6-fold increase in valvular calcification in those animals treated with leptin. In addition, the percent total lesion area demonstrating ALP-positive staining was 5.4+/-2.1-fold greater in leptin-treated mice when compared to nontreated control mice. This increase in ALP staining was also accompanied by an increase in the expression of the osteoblast-specific markers, osteocalcin, and osteopontin. CONCLUSIONS: Based on these observations, we conclude that leptin may increase cardiovascular risk by promoting osteogenic differentiation and thus vascular calcification.

Inhibition of osteolytic bone metastasis by unfractionated heparin.

In the current study, we examine heparin's anti-metastatic properties by using a well-defined mouse model of osteolytic bone metastasis. C57BL/6 mice were treated with increasing doses of unfractionated heparin (15, 20, or 25 units/mouse) 30 min prior to the left ventricular injection of GFP-transfected B16F10 melanoma cells. Heparin's effect on tumour burden and bone strength was then quantified 14 days later by bone histomorphometry and biomechanical testing, respectively. Based on histomorphometric analysis of the femurs, injection of GFP-transfected melanoma cells resulted in a 37% decrease in cancellous bone volume and a 68% increase in osteoclast surface. This was associated with a 13% reduction in bone strength as measured by biomechanical testing. However, when the mice were first pre-treated with 25 units of heparin, tumour burden was decreased by 73% and tumour cell-dependent decreases in both cancellous bone volume and bone strength were prevented. Based on these observations, we conclude that heparin inhibits the ability of tumour cells to metastasize to bone and that as such, prevents tumour cell-induced decreases in bone strength.