18F-Labeled brain-penetrant EGFR tyrosine kinase inhibitors for PET imaging of glioblastoma

Significant evidence suggests that the failure of clinically tested epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (e.g. erlotinib, lapatinib, gefitinib) in glioblastoma (GBM) patients is primarily attributed to insufficient brain penetration, resulting in inadequate exposure to the targeted cells. Molecular imaging tools can facilitate GBM drug development by visualizing drug biodistribution and confirming target expression and localization. To assess brain exposure via PET molecular imaging, we synthesized fluorine-18 isotopologues of two brain-penetrant EGFR tyrosine kinase inhibitors developed specifically for GBM. Adapting our recently reported radiofluorination of N-arylsydnones, we constructed an ortho-disubstituted [18F]fluoroarene as the key intermediate. The radiotracers were produced on an automated synthesis module in 7-8% activity yield with high molar activity. In vivo PET imaging revealed rapid brain uptake in rodents and tumor accumulation in an EGFR-driven orthotopic GBM xenograft model.

Deoxyfluorination of phenols for chemoselective 18F-labeling of peptides

The challenge of forming C-18F bonds is often a bottleneck in the development of new 18F-labeled tracer molecules for noninvasive functional imaging studies using positron emission tomography (PET). Nucleophilic aromatic substitution is the most widely employed reaction to functionalize aromatic substrates with the radioactive fluorine-18 but its scope is restricted to arenes containing electron-withdrawing substituents. Furthermore, many protic functional groups are incompatible with basic fluoride anions. Peptide substrates, which are highly desirable targets for PET molecular imaging, are particularly challenging to label with fluorine-18 because they are densely functionalized and sensitive to high temperatures and basic conditions. To expand the utility of nucleophilic aromatic substitution with fluorine-18, we describe two complementary procedures for the radiodeoxyfluorination of bench-stable and easy-to-access phenols that ensure rapid access to densely functionalized electron-rich and electron-poor 18F-aryl fluorides. The first procedure details the synthesis of an 18F-synthon and its subsequent ligation to the cysteine residue of Arg-Gly-Asp-Cys in 10.5 h from commercially available starting materials (189-min radiosynthesis). The second procedure describes the incorporation of commercially available CpRu(Fmoc-tyrosine)OTf into a fully protected peptide Lys-Met-Glu-(CpRu-Tyr)-Leu via solid-phase peptide synthesis and subsequent ruthenium-mediated uronium deoxyfluorination with fluorine-18 followed by deprotection, accomplished within 7 d (116-min radiosynthesis). Both radiolabeling methods are highly chemoselective and have conveniently been automated using commercially available radiosynthesis equipment so that the procedures described can be employed for the synthesis of peptide-based PET probes for in vivo imaging studies according to as low as reasonably achievable (ALARA) principles.

Oxidation of caspase-8 by hypothiocyanous acid enables TNF-mediated necroptosis

Necroptosis is a form of regulated cell death triggered by various host and pathogen-derived molecules during infection and inflammation. The essential step leading to necroptosis is phosphorylation of the mixed lineage kinase domain-like protein (MLKL) by receptor-interacting protein kinase 3 (RIPK3). Caspase 8 cleaves RIPKs to block necroptosis, so synthetic caspase inhibitors are required to study this process in experimental models. However, it is unclear how caspase-8 activity is regulated in a physiological setting. The active site cysteine of caspases is sensitive to oxidative inactivation, so we hypothesized that oxidants generated at sites of inflammation can inhibit caspase-8 and promote necroptosis. Here, we discovered that hypothiocyanous acid (HOSCN), an oxidant generated in vivo by heme peroxidases including myeloperoxidase and lactoperoxidase, is a potent caspase-8 inhibitor. We found HOSCN was able to promote necroptosis in mouse fibroblasts treated with tumor necrosis factor (TNF). We also demonstrate purified caspase-8 was inactivated by low concentrations of HOSCN, with the predominant product being a disulfide-linked dimer between Cys360 and Cys409 of the large and small catalytic subunits. We show oxidation still occurred in the presence of reducing agents, and reduction of the dimer was slow, consistent with HOSCN being a powerful physiological caspase inhibitor. While the initial oxidation product is a dimer, further modification also occurred in cells treated with HOSCN, leading to higher molecular weight caspase-8 species. Taken together, these findings indicate major disruption of caspase-8 function, and suggest a novel mechanism for the promotion of necroptosis at sites of inflammation.

Iterative wavefront optimization of ultrafast laser beams carrying orbital angular momentum

Structured intense laser beams offer degrees of freedom that are highly attractive for high-field science applications. However, the performance of high-power laser beams in these applications is often hindered by deviations from the desired spatiotemporal profile. This study reports the wavefront optimization of ultrafast Laguerre-Gaussian beams through the synergy of adaptive optics and genetic algorithm-guided feedback. The results indicate that the intensity fluctuations along the perimeter of the target ring-shaped profile can be reduced up to ∼15%. Furthermore, the radius of the ring beam profile can be tailored to a certain extent by establishing threshold fitting criteria. The versatility of this approach is experimentally demonstrated in conjunction with different focusing geometries.

An Organometallic Gold(III) Reagent for 18F Labeling of Unprotected Peptides and Sugars in Aqueous Media

The ¹⁸F labeling of unprotected peptides and sugars with a Au(III)-[¹⁸F]fluoroaryl complex is reported. The chemoselective method generates ¹⁸F-labeled S-aryl bioconjugates in an aqueous environment in 15 min with high radiochemical yields and displays excellent functional group tolerance. This approach utilizes an air and moisture stable, robust organometallic Au(III) complex and highlights the versatility of designer organometallic reagents as efficient agents for rapid radiolabeling.

Early postoperative functional outcomes following transoral surgery for oropharyngeal cancer: A systematic review

There has been increased interest in the use of transoral surgery (TOS) for the treatment of oropharyngeal cancer (OPC). This systematic review summarizes the available evidence for validated functional outcomes following TOS for OPC, within the early postoperative period. Key databases were searched. Primary TOS resections of human subjects were included. Validated functional outcomes extracted included instrumental assessment, clinician rated, and patient reported measures. Database searches yielded 7186 titles between 1990 and December 2020. Full-text articles were obtained for 296 eligible studies, which were screened and a resulting 14 studies, comprising 665 participants were included in the review. Oropharyngeal dysfunction following TOS was observed across all three categories of outcome measures (OMs) reported and was dependent on pretreatment function, T-classification, and tumor volume. Future investigations should include optimal OMs to be used in the postoperative setting to allow for conclusive comparisons.

Diagnostic yield from cardiac gene panel testing for inherited cardiac conditions in a large Irish cohort

Background

Inherited cardiomyopathies (hypertrophic, dilated and arrhythmogenic) and cardiac ion channelopathies (long QT, Brugada and CPVT) predispose to sudden cardiac death/sudden arrhythmic death syndrome. Given their genetically heterogenous nature, multi-gene DNA sequencing panels are useful to aid genetic diagnosis.

Purpose

Investigate the diagnostic yield from cardiac gene panel testing undertaken in patients (including molecular autopsy in deceased patients) referred to four clinical services from 2002 to 2020.

Methods

Data was collected by interrogation of departmental databases, family charts, and review of molecular genetic diagnostic reports.

Results

We evaluated molecular genetic diagnostic results from 835 individuals (461 males, 374 females) from 824 families, including 58 deceased patients who underwent molecular autopsy. The median age of the cohort was 44 years (range 0.1–86 years).

Testing for hypertrophic cardiomyopathy (HCM) and long QT syndrome (LQT) genes represented 36% and 32% of the cohort, respectively, with the remaining 32% accounting for other cardiomyopathies, arrhythmia syndromes or metabolic/syndromic diseases. The overall variant detection rate was 50% across all panel types. Three hundred and fifty patients (42%) carried a single variant, 68 patients (8%) carried multiple variants (up to a maximum of four), including two individuals who carried two actionable (pathogenic/likely pathogenic) variants each and 30 individuals (5%) with one actionable variant plus a variant of uncertain significance (VUS).

The overall diagnostic yield of at least one actionable variant was 28%. At least one VUS was detected in 27% of the cohort. Molecular autopsy yielded an actionable variant in 10% of patients, while 30% of the subcohort carried at least one VUS (up to maximum of two).

We found a positive association between female sex and the likelihood of detecting an actionable variant. By decade of age, detection of actionable variants ranged from 19% (60–69 years) to 41% (0–9 years). By panel type, actionable variants ranged from 14% (Brugada) to 35% (cardiomyopathy). The burden of VUS ranged from 22% (LQT) to 46% (dilated cardiomyopathy).

Altogether 234 actionable variants were detected in 26 genes, including seven metabolic or syndromic disease genes. From those with non-metabolic/syndromic forms of disease, 84% of actionable variants were detected in well established ICC genes. Analysis of gene-disease associations for VUS detected from HCM and LQT panels revealed that 10–25% were detected in genes now deemed to have only moderate or limited evidence of disease causation.

Conclusion

Most actionable variants in this cohort were detected in well-established ICC genes, suggesting that large gene panels offer little extra sensitivity compared to historic smaller gene panels. Despite recent gene curation efforts, the high burden of VUS remains a considerable challenge in ICC management.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): National Children's Research Centre

Positron Emission Tomography Tracer Design of Targeted Synthetic Peptides via 18F-Sydnone Alkyne Cycloaddition

Chemically synthesized, small peptides that bind with high affinity and specificity to CD8-expressing (CD8+) tumor-infiltrating T cells, yet retain the desirable characteristics of small molecules, hold valuable potential for diagnostic molecular imaging of immune response. Here, we report the development of ¹⁸F-labeled peptides targeting human CD8α with nanomolar affinity via the strain-promoted sydnone-alkyne cycloaddition with 4-[¹⁸F]fluorophenyl sydnone. The ¹⁸F-sydnone is produced in one step, in high radiochemical yield, and the peptide labeling proceeds rapidly. A hydrophilic chemical linker results in a tracer with favorable pharmacokinetic properties and improved image contrast, as demonstrated by in vivo PET imaging studies.

One-Step Synthesis of [18F]Fluoro-4-(vinylsulfonyl)benzene: A Thiol Reactive Synthon for Selective Radiofluorination of Peptides

Radiolabeled peptide-based molecular imaging probes exploit the advantages of large biologics and small molecules, providing both exquisite selectivity and favorable pharmacokinetic properties. Here, we report an operationally simple and broadly applicable approach for the ¹⁸F-fluorination of unprotected peptides via a new radiosynthon, [¹⁸F]fluoro-4-(vinylsulfonyl)benzene. This reagent demonstrates excellent chemoselectivity at the cysteine residue and rapid ¹⁸F-labeling of a diverse scope of peptides to generate stable thioether constructs.

Dual-layer everted saphenous vein patch for pediatric femoral artery repair following ECMO decannulation

Decannulation from pediatric veno-arterial extracorporeal membrane oxygenation (VA-ECMO) involves the removal of large arterial perfusion cannulas from relatively small lower extremity arteries. While these challenging repairs are frequently performed by general pediatric surgeons, there is little standardization with regard to vascular techniques within the pediatric surgery training paradigm, resulting in variability in the repair of these arteriotomies and potential future consequences for lower extremity perfusion and growth. Herein we present a technique for repair of large common femoral arteriotomies following removal of ECMO perfusion cannulas utilizing a dual-layer patch of ipsilateral saphenous vein harvested via the arterial cutdown incision. This vein segment is everted to maximize endothelial surface area of the patch and dual layered to provide additional support against aneurysmal degeneration. The described technique is an effective repair of arteriotomy following VA-ECMO decannulation, which minimizes vascular complications and is an accessible technique to those without advanced vascular surgical training. LEVEL OF EVIDENCE: Level IV; operative technique description with small case series.

Diversity and bioactivity of fungi associated with the marine sea cucumber Holothuria poli: disclosing the strains potential for biomedical applications

AIMS

Identification of the mycobiota associated to the marine echinoderm Holothuria poli and investigation of cytotoxic and pro-osteogenic potential of isolated strains.

METHODS AND RESULTS

Fungal strains were isolated from the animal's body-wall, intestine and faeces. The species identification was based on DNA barcoding and morphophysiological observations. Forty-seven species were identified, all are Ascomycota and mainly belonging to Aspergillus and Penicillium genera. Sixteen strains were grown on three media for chemical extraction. Cytotoxic activity was tested on a hepatic cancer cell line (HepG2), the cells viability was evaluated after treatment using a resazurin based assay (AlamarBlue). Pro-osteogenic activity was tested on human Mesenchymal stem cell, differentiation was measured as the alkaline phosphatase production through reaction with p-nitrophenylphosphate or as the cells ability to mineralize calcium using a colorimetric kit (StanBio). Cytotoxic activity was recorded for four fungal species while five of 48 extracts highlighted bioactivity towards human mesenchymal stem cells.

CONCLUSIONS

The presence of relevant animal-associated mycobiota was observed in H. poli and selected strains showed cytotoxic potential and pro-osteogenic activity.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our work represents the first report of a Mediterranean Sea cucumber mycobiota and highlights the isolates potential to synthetize compounds of pharmaceutical interest for regenerative medicine.

Tri-functional platform for construction of modular antibody fragments for in vivo 18F-PET or NIRF molecular imaging

Positron emission tomography (PET) molecular imaging is a powerful tool for interrogating physiological and biochemical processes to understand the biology of disease and advance therapeutic developments. Near-infrared fluorescence (NIRF) optical imaging has become increasingly popular for intraoperative staging to enable cellular resolution imaging of tumor margins during surgical resection. In addition, engineered antibody fragments have emerged as promising molecular imaging agents given their exquisite target selectivity, rapid systemic clearance and site-selective chemical modification. We report a tri-functional platform for construction of a modular antibody fragment that can rapidly be labeled with radionuclides or fluorophores for PET or NIRF molecular imaging of prostate stem cell antigen (PSCA).

To provide a universal approach towards the targeted delivery of PET and optical imaging agents, we have developed a tri-functional platform (TFP) for the facile construction of modular, target-specific tracers.

A Dual-Modality Linker Enables Site-Specific Conjugation of Antibody Fragments for 18F-Immuno-PET and Fluorescence Imaging

Antibody-based dual-modality (PET/fluorescence) imaging enables both presurgery antigen-specific immuno-PET for noninvasive whole-body evaluation and intraoperative fluorescence for visualization of superficial tissue layers for image-guided surgery. Methods: We developed a universal dual-modality linker (DML) that facilitates site-specific conjugation to a cysteine residue-bearing antibody fragment, introduction of a commercially available fluorescent dye (via an amine-reactive prosthetic group), and rapid and efficient radiolabeling via click chemistry with ¹⁸F-labeled trans-cyclooctene (¹⁸F-TCO). To generate a dual-modality antibody fragment-based imaging agent, the DML was labeled with the far-red dye sulfonate cyanine 5 (sCy5), site-specifically conjugated to the C-terminal cysteine of the anti-prostate stem cell antigen (PSCA) cys-diabody A2, and subsequently radiolabeled by click chemistry with ¹⁸F-TCO. The new imaging probe was evaluated in a human PSCA-positive prostate cancer xenograft model by sequential immuno-PET and optical imaging. Uptake in target tissues was confirmed by ex vivo biodistribution. Results: We successfully synthesized a DML for conjugation of a fluorescent dye and ¹⁸F. The anti-PSCA cys-diabody A2 was site-specifically conjugated with either DML or sCy5 and radiolabeled via click chemistry with ¹⁸F-TCO. Immuno-PET imaging confirmed in vivo antigen-specific targeting of prostate cancer xenografts as early as 1 h after injection. Rapid renal clearance of the 50-kDa antibody fragment enables same-day imaging. Optical imaging showed antigen-specific fluorescent signal in PSCA-positive xenografts and high contrast to surrounding tissue and PSCA-negative xenografts. Conclusion: The DML enables site-specific conjugation away from the antigen-binding site of antibody fragments, with a controlled linker-to-protein ratio, and combines signaling moieties for 2 imaging systems into 1 molecule. Dual-modality imaging could provide both noninvasive whole-body imaging with organ-level biodistribution and fluorescence image-guided identification of tumor margins during surgery.

Automated concentration of [18F]fluoride into microliter volumes

Concentration of [18F]fluoride has been mentioned in literature, however, reports have lacked details about system designs, operation, and performance. Here, we describe in detail a compact, fast, fully-automated concentration system based on a micro-sized strong anion exchange cartridge. The concentration of radionuclides enables scaled-up microfluidic synthesis. Our system can also be used to provide highly concentrated [18F]fluoride with minimal water content. We demonstrate how the concentrator can produce varying concentrations of [18F]fluoride for the macroscale synthesis of N-boc-5-[18F]fluoroindole without an azeotropic drying process, while enabling high starting radioactivity. By appropriate choice of solid-phase resin, flow conditions, and eluent solution, we believe this approach can be extended beyond [18F]fluoride to other radionuclides.

Readily Accessible Ambiphilic Cyclopentadienes for Bioorthogonal Labeling

A new class of bioorthogonal reagents based on the cyclopentadiene scaffold is described. The diene 6,7,8,9-tetrachloro-1,4-dioxospiro[4,4]nona-6,8-diene (a tetrachlorocyclopentadiene ketal, TCK) is ambiphilic and self-orthogonal with remarkable stability. The diene reacts rapidly with a trans-cyclooctene and an endo-bicyclononyne, but slowly with dibenzoazacyclooctyne (DIBAC), allowing for tandem labeling studies with mutually orthogonal azides that react rapidly with DIBAC. TCK analogues are synthesized in three steps from inexpensive, commercially available starting materials.

Origins of halogen effects in bioorthogonal sydnone cycloadditions

Halogen substituents increase sydnone cycloaddition reactivities substantially. Fluoro-sydnones are superior to bromo- and chloro-sydnones, and can achieve extremely high second-order rate constants with strained alkynes. Computational studies have revealed the fluorine substituent increases the reactivity of sydnone mainly by lowering its distortion energy.

An evidence-based oral health promotion programme: Lessons from Leicester

OBJECTIVES

To provide an overview and draw lessons from the establishment of a local oral health promotion programme for preschool children in Leicester, England (2013-2017). The article provides information on the strategic approach taken in Leicester, one of the most ethnically diverse cities in England, and also one of the most deprived. Over a third of children aged 3 years, and half of those aged 5 years, have experience of obvious dental decay.

METHODS

A description of the evolution and development of the programme is provided along with commentary by the authors. This includes the origins, design and evaluation of the programme.

RESULTS

Progress so far has been promising. There has been a statistically significant 8% decrease in the proportion of 5-year-old children in Leicester with dental decay from 2011/2012 to 2014/2015. This will need to be sustained and further developed to deliver the 10% reduction required within the strategy.

CONCLUSIONS

The successful implementation of a local oral health improvement programme in Leicester has required leadership to coordinate a multiagency partnership approach to embedding effective concepts and realising opportunities collaboratively. However, longer term sustainability remains a concern.

Secreted factors from metastatic prostate cancer cells stimulate mesenchymal stem cell transition to a pro-tumourigenic 'activated' state that enhances prostate cancer cell migration

Mesenchymal stem cells (MSCs) are a heterogeneous population of multipotent cells that are capable of differentiating into osteocytes, chondrocytes and adipocytes. Recently, MSCs have been found to home to the tumour site and engraft in the tumour stroma. However, it is not yet known whether they have a tumour promoting or suppressive function. We investigated the interaction between prostate cancer cell lines 22Rv1, DU145 and PC3, and bone marrow-derived MSCs. MSCs were 'educated' for extended periods in prostate cancer cell conditioned media and PC3-educated MSCs were found to be the most responsive with a secretory profile rich in pro-inflammatory cytokines. PC3-educated MSCs secreted increased osteopontin (OPN), interleukin-8 (IL-8) and fibroblast growth factor-2 (FGF-2) and decreased soluble fms-like tyrosine kinase-1 (sFlt-1) compared to untreated MSCs. PC3-educated MSCs showed a reduced migration and proliferation capacity that was dependent on exposure to PC3-conditioned medium. Vimentin and α-smooth muscle actin (αSMA) expression was decreased in PC3-educated MSCs compared to untreated MSCs. PC3 and DU145 education of healthy donor and prostate cancer patient-derived MSCs led to a reduced proportion of FAP+ αSMA+ cells contrary to characteristics commonly associated with cancer associated fibroblasts (CAFs). The migration of PC3 cells was increased toward both PC3-educated and DU145-educated MSCs compared to untreated MSCs, while DU145 migration was only enhanced toward patient-derived MSCs. In summary, MSCs developed an altered phenotype in response to prostate cancer conditioned medium which resulted in increased secretion of pro-inflammatory cytokines, modified functional activity and the chemoattraction of prostate cancer cells.

Synthesis of [18 F]Fluoroarenes by Nucleophilic Radiofluorination of N-Arylsydnones

A practical method for radiofluorination of anilines with [18 F]fluoride via N-arylsydnone intermediates is described. These precursors are stable, easy to handle and facilitate direct and regioselective 18 F-labeling to prepare [18 F]fluoroarenes. The value of this methodology is further highlighted by successful application to prepare an 18 F-labeled neuropeptide.

Prognostic factors and survival in non-central nervous system rhabdoid tumors

INTRODUCTION

Non-central nervous system (non-CNS) rhabdoid tumors tend to present at a young age and have an extremely aggressive course, with dismal overall survival rates. Inactivation of the tumor suppressor gene SMARCB1 has been shown in rhabdoid tumors regardless of anatomic location, suggesting a common genetic basis. We retrospectively analyzed our institutional experience with non-CNS rhabdoid tumors to determine overall survival and prognostic variables.

METHODS

We reviewed records of pediatric patients (age<22y) with non-CNS rhabdoid tumor at our institution between 1980 and 2014. Variables evaluated for correlation with survival included: age > or <1.5years (median) at diagnosis, M1 status, and radiation therapy. The log-rank test was used to compare Kaplan-Meier probability distributions with P values adjusted for multiple testing using the false discovery rate approach.

RESULTS

Nineteen consecutive patients (10 female) with histologically verified rhabdoid tumor were identified. Mean age at diagnosis was 3.2years (median 1.5y, range 1.3mo-21.8y). Primary tumors were located in the kidney (n=10), head and neck (n=5), and in the liver, thigh, mediastinum and retroperitoneum (n=1 each). SMARCB1 expression was absent in all 10 patients tested. Eight patients had distant metastases at diagnosis. Median overall survival was 1.2years. Age greater than the median and radiation therapy were associated with better outcome, with a median overall survival of 2.7years (P=0.049 and P=0.003, respectively).

CONCLUSION

Survival rates for rhabdoid tumor remain poor, but prognosis is better in older children, regardless of primary tumor location. Because of its rarity, clinical trials with present agents are difficult to conduct. Further progress will require a focus on therapies targeted at tumor biology rather than anatomic location for non-CNS rhabdoid tumors.

Perceptions and Practices of Mass Bat Exposure Events in the Setting of Rabies Among U.S. Public Health Agencies

Current guidelines in the setting of exposures to potentially rabid bats established by the Advisory Committee on Immunization Practices (ACIP) address post-exposure prophylaxis (PEP) administration in situations where a person may not be aware that a bite or direct contact has occurred and the bat is not available for diagnostic testing. These include instances when a bat is discovered in a room where a person awakens from sleep, is a child without an adult witness, has a mental disability or is intoxicated. The current ACIP guidelines, however, do not address PEP in the setting of multiple persons exposed to a bat or a bat colony, otherwise known as mass bat exposure (MBE) events. Due to a dearth of recommendations for response to these events, the reported reactions by public health agencies have varied widely. To address this perceived limitation, a survey of 45 state public health agencies was conducted to characterize prior experiences with MBE and practices to mitigate the public health risks. In general, most states (69% of the respondents) felt current ACIP guidelines were unclear in MBE scenarios. Thirty-three of the 45 states reported prior experience with MBE, receiving an average of 16.9 MBE calls per year and an investment of 106.7 person-hours annually on MBE investigations. PEP criteria, investigation methods and the experts recruited in MBE investigations varied between states. These dissimilarities could reflect differences in experience, scenario and resources. The lack of consistency in state responses to potential mass exposures to a highly fatal disease along with the large contingent of states dissatisfied with current ACIP guidance warrants the development of national guidelines in MBE settings.

Image-defined risk factors for nephrectomy in patients undergoing neuroblastoma resection

BACKGROUND

Although nephrectomy rates are higher in children with neuroblastoma who have image-defined risk factors and/or high-risk disease who undergo resection prior to chemotherapy, no published data outline the key radiographic and clinical characteristics associated with nephrectomy.

METHODS

With IRB approval, imaging studies of children undergoing primary resection of intraabdominal neuroblastoma between 2000 and 2014 were retrospectively reviewed. Fisher's exact and Wilcoxon rank-sum tests were used to compare categorical and continuous variables, respectively, with p-values adjusted for multiple testing using the false discovery rate approach.

RESULTS

Twenty-seven of 380 consecutive patients with CT imaging obtained prior to primary neuroblastoma resection underwent partial or total nephrectomy. On preoperative imaging, renal vessel narrowing and encasement and tumor invasion of the renal hilum, pelvis, and/or parenchyma were present significantly more frequently among patients undergoing nephrectomy. Delayed renal excretion of contrast, hydronephrosis, and tumors with MYCN amplification were also more prevalent in the nephrectomy group.

CONCLUSION

Encasement and narrowing of renal vessels, delayed excretion, and tumor invasion into the kidney, particularly pelvis and capsule invasion, are significantly associated with partial or total nephrectomy at initial neuroblastoma resection. These observations provide valuable information for surgical planning as well as presurgical discussions with families prior to neuroblastoma resection.

A Transmetalation Reaction Enables the Synthesis of [18F]5-Fluorouracil from [18F]Fluoride for Human PET Imaging

Translation of new ¹⁸F-fluorination reactions to produce radiotracers for human positron emission tomography (PET) imaging is rare because the chemistry must have useful scope and the process for ¹⁸F-labeled tracer production must be robust and simple to execute. The application of transition metal mediators has enabled impactful ¹⁸F-fluorination methods, but to date none of these reactions have been applied to produce a human-injectable PET tracer. In this article we present chemistry and process innovations that culminate in the first production from [¹⁸F]fluoride of human doses of [¹⁸F]5-fluorouracil, a PET tracer for cancer imaging in humans. The first preparation of nickel σ-aryl complexes by transmetalation from arylboronic acids or esters was developed and enabled the synthesis of the [¹⁸F]5-fluorouracil precursor. Routine production of >10 mCi doses of [¹⁸F]5-fluorouracil was accomplished with a new instrument for azeotrope-free [¹⁸F]fluoride concentration in a process that leverages the tolerance of water in nickel-mediated ¹⁸F-fluorination.

Evolutionary divergence of the necroptosis effector MLKL

The pseudokinase, MLKL (mixed-lineage kinase domain-like), is the most terminal obligatory component of the necroptosis cell death pathway known. Phosphorylation of the MLKL pseudokinase domain by the protein kinase, receptor interacting protein kinase-3 (RIPK3), is known to be the key step in MLKL activation. This phosphorylation event is believed to trigger a molecular switch, leading to exposure of the N-terminal four-helix bundle (4HB) domain of MLKL, its oligomerization, membrane translocation and ultimately cell death. To examine how well this process is evolutionarily conserved, we analysed the function of MLKL orthologues. Surprisingly, and unlike their mouse, horse and frog counterparts, human, chicken and stickleback 4HB domains were unable to induce cell death when expressed in murine fibroblasts. Forced dimerization of the human MLKL 4HB domain overcame this defect and triggered cell death in human and mouse cell lines. Furthermore, recombinant proteins from mouse, frog, human and chicken MLKL, all of which contained a 4HB domain, permeabilized liposomes, and were most effective on those designed to mimic plasma membrane composition. These studies demonstrate that the membrane-permeabilization function of the 4HB domain is evolutionarily conserved, but reveal that execution of necroptotic death by it relies on additional factors that are poorly conserved even among closely related species.

Salvage rates after progression of high-risk neuroblastoma with a soft tissue mass

PURPOSE

Treatment of progression in high-risk neuroblastoma remains challenging despite improved survival. We retrospectively evaluated outcomes in children with a first progression that included soft-tissue masses.

METHODS

We reviewed records of 903 consecutive children with high-risk neuroblastoma diagnosed between 2004 and 2014, and identified 42 whose first progression included soft-tissue masses. Data on demographics, disease characteristics, treatment, and survival were collected. Primary outcome was 5-year overall survival (OS) from time of first progression. Secondary outcomes were local disease-free progression (LDFR) and progression-free survival (PFS) postprogression. We evaluated the prognostic significance of concomitant bone/bone marrow involvement, MYCN status, and multifocality of soft tissue relapse.

RESULTS

Median age at diagnosis was 3.0 (range: 1-10.7) years. Median time to first relapse or progression was 1.2 (range: 0.1-4.5) years after complete remission or minimal stable residual disease. Twelve (29%) patients had concomitant bone or marrow involvement at progression/relapse. There were 11 (26%) patients with International Neuroblastoma Staging System stage 3 disease (all with MYCN amplification), and 31 (74%) with stage 4 disease (12 with MYCN amplification). Nine (21%) patients had multifocal soft tissue progression. R1 resection was achieved in 41 children (95%), 38 (95%) of whom also received salvage radiation therapy. Five-year OS postprogression was 35% (95% CI: 19-51%), 5-year LDFS was 52% (95% CI: 32-72%), and 5-year PFS postprogression was 20% (95% CI: 6-34%).

CONCLUSION

Among children with high-risk neuroblastoma who underwent aggressive treatment of a first soft-tissue recurrence, 5-year postprogression overall survival was 34%. Multifocality and MYCN amplification were the predominant prognostic correlates for worse survival.

Discovery of new mutually orthogonal bioorthogonal cycloaddition pairs through computational screening

Density functional theory (DFT) calculations and experiments in tandem led to discoveries of new reactivities and selectivities involving bioorthogonal sydnone cycloadditions. Dibenzocyclooctyne derivatives (DIBAC and BARAC) were identified to be especially reactive dipolarophiles, which undergo the (3 + 2) cycloadditions with N-phenyl sydnone with the rate constant of up to 1.46 M-1 s-1. Most significantly, the sydnone-dibenzocyclooctyne and norbornene-tetrazine cycloadditions were predicted to be mutually orthogonal. This was validated experimentally and used for highly selective fluorescence labeling of two proteins simultaneously.

The genomic landscape of fibrolamellar hepatocellular carcinoma: whole genome sequencing of ten patients

Fibrolamellar hepatocellular carcinoma is a rare, malignant liver tumor that often arises in the otherwise normal liver of adolescents and young adults. Previous studies have focused on biomarkers and comparisons to traditional hepatocellular carcinoma, and have yielded little data on the underlying pathophysiology. We performed whole genome sequencing on paired tumor and normal samples from 10 patients to identify recurrent mutations and structural variations that could predispose to oncogenesis. There are relatively few coding, somatic mutations in this cancer, putting it on the low end of the mutational spectrum. Aside from a previously described heterozygous deletion on chromosome 19 that encodes for a functional, chimeric protein, there were no other recurrent structural variations that contribute to the tumor genotype. The lack of a second-hit mutation in the genomic landscape of fibrolamellar hepatocellular carcinoma makes the DNAJB1-PRKACA fusion protein the best target for diagnostic and therapeutic advancements. The mutations, altered pathways and structural variants that characterized fibrolamellar hepatocellular carcinoma were distinct from those in hepatocellular carcinoma, further defining it as a distinct carcinoma.

Gastric Volvulus Following Left Pneumonectomy in an Adolescent Patient

Gastric volvulus is a rare post-pneumonectomy complication. Although it has been described previously, published cases are limited to an older patient population. We report the youngest case of postpneumonectomy gastric volvulus to date, occurring in an 18-year-old male with a history of inflammatory myofibroblastic pseudotumor who underwent left intrapericardial pneumonectomy, and presented 13 years later with chronic intermittent mesenteroaxial gastric volvulus. While postpneumonectomy gastric volvulus is a rare occurrence, it should remain in the differential diagnosis in postoperative thoracic surgical patients presenting with chest pain.

Abstract 4730: Molecular analysis of the pediatric cancer fibrolamellar hepatocellular carcinoma

Genomic analysis of the pediatric cancer fibrolamellar hepatocellular carcinoma

Fibrolamellar hepatocellular carcinoma (FLHCC) is a rare liver tumor that usually occurs in adolescents and young adults. Originally considered a variant of hepatocellular carcinoma (HCC), FLHCC is characterized by hepatocytes with deeply eosinophilic, granular cytoplasm interspersed with fibrous bands, without signs of cirrhosis as in HCC. Since little is known of its molecular pathogenesis, we performed RNA-seq and whole genome sequencing of FLHCC paired with normal liver from the same patient.

Our results demonstrated that the majority of the DNA is unremarkable with few recurrent mutations or structural variants such as amplifications or inversions The major finding is a heterogeneous deletion of ∼400 kB in chromosome 19 which produces a chimeric transcript and a fully functional protein, a fusion between the heat shock protein DNAJB1 and the catalytic subunit of protein kinase A (PRKACA). Our initial observation of this chimera in 15 out of 15 patients has now been expanded to 116 out of 116 patients. Differential expression analysis of RNA-seq revealed many changes in the gene expression in FLHCC as compared to its paired normal liver. These changes were highly consistent from patient to patient, suggesting a unifying pathogenesis. The RNA-seq from our FLHCC samples had little in common with HCC samples from the TCGA or published reports of other cancers. An analysis of protein expression correlated well with the RNA-seq results. Some observed changes can directly be linked to increased activity of PRKACA. Other changes involve pathways known to participate in the initiation and progression of other cancers, which, along with an increase of PRKACA activity, represent targets for therapeutic intervention. Several of these targets are now being explored in cellular models, genetic, and PDX mouse models, as well as clinical trials.

Citation Format: Elana P. Simon, Joshua N. Honeyman, David G. Darcy, Brad R. Rosenberg, Iris I. Lim, Jennifer M. Murphy, Ben Farber, Gadi Lalazar, Catherine Freije, Michael P. La Quaglia, Sanford M. Simon. Molecular analysis of the pediatric cancer fibrolamellar hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4730. doi:10.1158/1538-7445.AM2015-4730

Abstract LB-214: DNAJB1-PRKACA chimera increases Aurora kinase A expression in fibrolamellar hepatocellular carcinoma

Purpose: Treatment of fibrolamellar hepatocellular carcinoma (FL-HCC), a rare liver cancer affecting the pediatric and adolescent population, is limited to surgical resection with no agents or therapeutic modalities available for unresectable disease. There has been recent interest in using Aurora kinase A (AURKA) inhibitors, with a clinical trial evaluating its efficacy in FL-HCC pending. Previously, we described a consistent single deletion of approximately 400 kB in chromosome 19 that results in a chimera between the heat shock protein DNAJB1 and the catalytic subunit of protein kinase A, PRKACA, in all FL-HCC tumor tissue studied. Furthermore, comparative ribonucleic acid sequence analysis has demonstrated that expression of AURKA, a regulator of cytokinesis and mitosis, is increased in FL-HCC tumor tissue compared with adjacent normal tissue. We hypothesize that the DNAJB1-PRKACA chimera is responsible for changes in AURKA expression in FL-HCC.

Methods: The DNAJB1-PRKACA chimera was cloned into a lentiviral vector with a fluorescent reporter. Two stable cell lines (HeLa and a hepatocyte cell line, Huh-7) were transduced with a lentivirus containing either an empty multicloning site (control) or the DNAJB1-PRKACA chimera. Transduction was confirmed by the presence of a positive epifluorescent signal and immunoblots showing expression of the chimeric protein. Microarray data were evaluated for changes in AURKA expression while immunoblots were analyzed for the presence of AURKA in all transduced cells.

Results: Microarray analysis showed an increase in AURKA transcripts in cells stably expressing the DNAJB1-PRKACA chimera. Compared to cells transduced with the control lentivirus, HeLa and Huh-7 cells transduced with the DNAJB1-PRKACA chimera demonstrated an increase in AURKA on immunoblots. Levels of a loading control, actin, were equivalent, indicating equal levels of protein examined between samples.

Conclusion: Expression of the DNAJB1-PRKACA chimera results in an increase in AURKA. Upregulation of AURKA, in turn, may be responsible for subsequent tumor formation in FL-HCC. This finding further supports the DNAJB1-PRKACA chimera's role in the pathogenesis of FL-HCC and provides a potential therapeutic target for a disease that has no effective treatment besides surgery.

Citation Format: Irene Isabel P. Lim, Emily A. Greene-Colozzi, Jennifer M. Murphy, Todd E. Heaton, Sanford M. Simon, Michael P. LaQuaglia. DNAJB1-PRKACA chimera increases Aurora kinase A expression in fibrolamellar hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-214. doi:10.1158/1538-7445.AM2015-LB-214

Fully-automated synthesis of 16β-(18)F-fluoro-5α-dihydrotestosterone (FDHT) on the ELIXYS radiosynthesizer

Noninvasive in vivo imaging of androgen receptor (AR) levels with positron emission tomography (PET) is becoming the primary tool in prostate cancer detection and staging. Of the potential (18)F-labeled PET tracers, (18)F-FDHT has clinically shown to be of highest diagnostic value. We demonstrate the first automated synthesis of (18)F-FDHT by adapting the conventional manual synthesis onto the fully-automated ELIXYS radiosynthesizer. Clinically-relevant amounts of (18)F-FDHT were synthesized on ELIXYS in 90 min with decay-corrected radiochemical yield of 29±5% (n=7). The specific activity was 4.6 Ci/µmol (170 GBq/µmol) at end of formulation with a starting activity of 1.0 Ci (37 GBq). The formulated (18)F-FDHT yielded sufficient activity for multiple patient doses and passed all quality control tests required for routine clinical use.

Risky behaviors, e-cigarette use and susceptibility of use among college students

BACKGROUND

Since 2007, there has been a rise in the use of electronic cigarettes (e-cigarettes). The present study uses cross-sectional data (2013) to examine prevalence, correlates and susceptibility to e-cigarettes among young adults.

METHODS

Data were collected using an Internet survey from a convenience sample of 1437, 18-23 year olds attending four colleges/universities in Upstate New York. Results were summarized using descriptive statistics; logistic regression models were analyzed to identify correlates of e-cigarette use and susceptibility to using e-cigarettes.

RESULTS

Nearly all respondents (95.5%) reported awareness of e-cigarettes; 29.9% were ever users and 14.9% were current users. Younger students, males, non-Hispanic Whites, respondents reporting average/below average school ability, ever smokers and experimenters of tobacco cigarettes, and those with lower perceptions of harm regarding e-cigarettes demonstrated higher odds of ever use or current use. Risky behaviors (i.e., tobacco, marijuana or alcohol use) were associated with using e-cigarettes. Among never e-cigarette users, individuals involved in risky behaviors or, with lower harm perceptions for e-cigarettes, were more susceptible to future e-cigarette use.

CONCLUSIONS

More e-cigarette users report use of another nicotine product besides e-cigarettes as the first nicotine product used; this should be considered when examining whether e-cigarette use is related to cigarette susceptibility. Involvement in risky behaviors is related to e-cigarette use and susceptibility to e-cigarette use. Among college students, e-cigarette use is more likely to occur in those who have also used other tobacco products, marijuana, and/or alcohol.

Experience with retroperitoneal partial nephrectomy in bilateral Wilms tumor

INTRODUCTION

Retroperitoneal partial nephrectomy has not been studied as a surgical approach for children with bilateral Wilms tumor. There are advantages to this technique, including isolation of urine leaks to the retroperitoneum, decreased risk of bowel injury, and decreased time to resuming a diet. Presently, all bilateral Wilms tumors are treated with neoadjuvant chemotherapy and attempted nephron-sparing surgery. In this study, we compare the outcomes of the retroperitoneal and transabdominal approaches in doing partial nephrectomy for bilateral Wilms tumor.

METHODS

With the institutional review board approval, we reviewed records of 14 pediatric patients with metachronous or synchronous bilateral Wilms tumors who underwent surgery after chemotherapy between 1994 and 2014. Only operative procedures with the intent to cure were included (n=15) and of these, 5 procedures were retroperitoneal and 10 were transabdominal in approach. Individual kidneys operated upon (n=26) were analyzed using the preoperative radius exophytic/endophytic nearness anterior/posterior location nephrometry score to ensure that resected tumors were comparable between the two surgical groups. Charts were retrospectively analyzed for intraoperative parameters and postoperative course. Differences between parameters were evaluated using Mann-Whitney and chi-square tests.

RESULTS

Resected tumors in both surgical treatment groups had comparable sizes, nephrometry scores, and rates of anaplasia. Operative time, blood loss, and transfusion requirement were similar between the two groups. The extent of lymph node sampling and rates of R0 resection were equivalent. One adverse intraoperative event, a bowel enterotomy, was seen in the transabdominal group. Patients after retroperitoneal partial nephrectomy required half the time to return to an oral diet as compared with those after a transabdominal surgery, approaching statistical significance (p=0.08). Rates of the postoperative urine leak were similar, though two in the transabdominal group required reoperation for drainage. There were four recurrences, all in the transabdominal group.

CONCLUSION

Our experience demonstrates that the retroperitoneal approach is equivalent to the transabdominal technique with regards to intraoperative complications, lymph node dissection, and R0 resection. Advantages include less time to resumption of oral feeding, decreased risk of bowel injury, and isolation of urine leaks to the retroperitoneum. It should be considered a viable surgical option in the treatment of bilateral Wilms tumors.

Advances in the surgical treatment of neuroblastoma: a review

Neuroblastoma prognosis varies tremendously based on the stage and biologic features of the tumor. Treatment varies depending on the risk group and can range from surgery alone for stage 1 tumors to aggressive multimodality treatment for MYCN-amplified tumors. Although surgery plays a role in the diagnosis and management of all stages of neuroblastoma, the importance of that role, especially the extent of resection, in high-risk neuroblastoma continues to evolve. In the past five years, there have been several advances in neuroblastoma surgery. Studies have demonstrated that patients with low-risk disease can be treated with surgery alone, and in a subset of patients who are neonatally diagnosed with adrenal tumors, surgery can be avoided in 80%. Recent abstracts have supported a role for >90% resection of the primary tumor in high-risk patients. This article also reviews the surgical approaches to difficult thoracic and abdominal tumors, as well as the role for minimally invasive surgery in the management of localized neuroblastoma.

Human osteoarthritic synovium impacts chondrogenic differentiation of mesenchymal stem cells via macrophage polarisation state

OBJECTIVE

Mesenchymal stem cells (MSCs) are a promising cell type for the repair of damaged cartilage in osteoarthritis (OA). However, OA synovial fluid and factors secreted by synovium impede chondrogenic differentiation of MSCs, and the mechanism responsible for this effect remains unclear. In this study, we sought to investigate whether M1 and M2 synovial macrophages can contribute to the inhibition of MSC chondrogenesis.

DESIGN

The constitution of synovial macrophage subsets was analysed by immunohistochemical staining of human OA synovium sections for CD86 (M1 marker) and CD206 (M2 marker). To assess the effect of synovial macrophages on chondrogenesis, collagen type II (COL2) and aggrecan (ACAN) gene expression were compared between MSCs undergoing chondrogenic differentiation in medium conditioned (CM) by human OA synovial explants, human synovial macrophages and fibroblasts, or peripheral blood derived primary human monocytes differentiated towards an M1 or M2 phenotype.

RESULTS

OA synovium contained both M1 and M2 macrophages. Medium conditioned by synovial macrophages (CD45 + plastic adherent cells) down-regulated chondrogenic gene expression by MSCs. Additionally, CM of M1 polarised monocytes significantly decreased COL2 and ACAN gene expression by MSCs; this effect was not observed for treatment with CM of M2 polarised monocytes.

CONCLUSION

MSC chondrogenesis is inhibited by OA synovium CM through factors secreted by synovial macrophages and our findings suggest that M1 polarised subsets are potential mediators of this anti-chondrogenic effect. Modulation of macrophage phenotype may serve as a beneficial strategy to maximise the potential of MSCs for efficient cartilage repair.

Detection of a recurrent DNAJB1-PRKACA chimeric transcript in fibrolamellar hepatocellular carcinoma

Fibrolamellar hepatocellular carcinoma (FL-HCC) is a rare liver tumor affecting adolescents and young adults with no history of primary liver disease or cirrhosis. We identified a chimeric transcript that is expressed in FL-HCC but not in adjacent normal liver and that arises as the result of a ~400-kilobase deletion on chromosome 19. The chimeric RNA is predicted to code for a protein containing the amino-terminal domain of DNAJB1, a homolog of the molecular chaperone DNAJ, fused in frame with PRKACA, the catalytic domain of protein kinase A. Immunoprecipitation and Western blot analyses confirmed that the chimeric protein is expressed in tumor tissue, and a cell culture assay indicated that it retains kinase activity. Evidence supporting the presence of the DNAJB1-PRKACA chimeric transcript in 100% of the FL-HCCs examined (15/15) suggests that this genetic alteration contributes to tumor pathogenesis.

Necroptosis induced by RIPK3 requires MLKL but not Drp1

Necroptosis is a mechanism by which cells can kill themselves that does not require caspase activity or the presence of the pro-apoptotic Bcl-2 family members Bax or Bak. It has been reported that RIPK3 (receptor interacting protein kinase 3) activates MLKL (mixed lineage kinase domain-like) to cause cell death that requires dynamin-related protein 1 (Drp1), because survival was increased in cells depleted of Drp1 or treated with the Drp1 inhibitor mdivi-1. To analyze necroptosis in a system that does not require addition of tumor necrosis factor (TNF), we used a construct that allows RIPK3 to be induced in cells, and then dimerized via an E. coli gyrase domain fused to its carboxyl-terminus, using the dimeric gyrase binding antibiotic coumermycin. We have previously shown elsewhere that RIPK3 dimerized in this manner not only induces necroptosis but also apoptosis, which can be inhibited by the broad-spectrum caspase inhibitor Q-VD-OPh (QVD). In response to RIPK3 dimerization, wild-type mouse embryonic fibroblasts (MEFs) underwent cell death that was reduced but not completely blocked by QVD. In contrast, death upon dimerization of RIPK3 in Mlkl^−/− MEFs was completely inhibited with QVD, confirming that MLKL is required for necroptosis. Similar to wild-type MEFs, most Drp1^−/− MEFs died when RIPK3 was activated, even in the presence of QVD. Furthermore, overexpression of wild-type MLKL or dominant active mutants of MLKL (Q343A or S345E/S347E) caused death of wild-type and Drp1^−/− MEFs that was not inhibited with QVD. These results indicate that necroptosis caused by RIPK3 requires MLKL but not Drp1.

Co-targeting of convergent nucleotide biosynthetic pathways for leukemia eradication

Co-targeting of both de novo and salvage pathways for dCTP biosynthesis shows efficacy in T-ALL and B-ALL.

Pharmacological targeting of metabolic processes in cancer must overcome redundancy in biosynthetic pathways. Deoxycytidine (dC) triphosphate (dCTP) can be produced both by the de novo pathway (DNP) and by the nucleoside salvage pathway (NSP). However, the role of the NSP in dCTP production and DNA synthesis in cancer cells is currently not well understood. We show that acute lymphoblastic leukemia (ALL) cells avoid lethal replication stress after thymidine (dT)-induced inhibition of DNP dCTP synthesis by switching to NSP-mediated dCTP production. The metabolic switch in dCTP production triggered by DNP inhibition is accompanied by NSP up-regulation and can be prevented using DI-39, a new high-affinity small-molecule inhibitor of the NSP rate-limiting enzyme dC kinase (dCK). Positron emission tomography (PET) imaging was useful for following both the duration and degree of dCK inhibition by DI-39 treatment in vivo, thus providing a companion pharmacodynamic biomarker. Pharmacological co-targeting of the DNP with dT and the NSP with DI-39 was efficacious against ALL models in mice, without detectable host toxicity. These findings advance our understanding of nucleotide metabolism in leukemic cells, and identify dCTP biosynthesis as a potential new therapeutic target for metabolic interventions in ALL and possibly other hematological malignancies.

Chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells in a simulated osteochondral environment is hydrogel dependent

Hydrogels pose interesting features for cartilage regeneration strategies, such as the option for injectability and in situ gelation resulting in optimal filling of defects. We aimed to study different hydrogels for their capability to support chondrogenesis of human bone marrow-derived mesenchymal stem cells (hBMSCs). hBMSCs were encapsulated in alginate, alginate with hyaluronic acid (alginate/HA), fibrin or thermoresponsive HA grafted with poly(N-isopropyl acrylamide) side-chains (HA-pNIPAM). Glycosaminoglycan production and cartilage-related gene expression were significantly higher in hBMSC-alginate and hBMSC-fibrin constructs than in the other constructs. Supplementation of alginate with HA was not beneficial. hBMSC-alginate, hBMSC-fibrin and hBMSC-HA-pNIPAM constructs were placed in simulated defects in osteochondral biopsies and cultured in vitro for 28 d. Biopsies containing hBMSC-alginate and hBMSC-fibrin were implanted subcutaneously in nude mice for 12 weeks. hBMSC-alginate constructs had significantly higher cartilage-related gene expression after 28 d of culture as well as significantly more safranin-O positive repair tissue after 12 weeks in vivo than hBMSC-fibrin constructs. Although initial experiments with hBMSC-hydrogel constructs suggested comparable results of hBMSC-alginate, hBMSC-fibrin and hBMSC-HA-pNIPAM constructs, culture in the osteochondral biopsy model in vitro as well as in vivo revealed differences, suggests that chondrogenesis of hBMSCs in an osteochondral environment is hydrogel-dependent.

Structural characterization of new deoxycytidine kinase inhibitors rationalizes the affinity-determining moieties of the molecules

Deoxycytidine kinase (dCK) is a key enzyme in the nucleoside salvage pathway that is also required for the activation of several anticancer and antiviral nucleoside analog prodrugs. Additionally, dCK has been implicated in immune disorders and has been found to be overexpressed in several cancers. To allow the probing and modulation of dCK activity, a new class of small-molecule inhibitors of the enzyme were developed. Here, the structural characterization of four of these inhibitors in complex with human dCK is presented. The structures reveal that the compounds occupy the nucleoside-binding site and bind to the open form of dCK. Surprisingly, a slight variation in the nature of the substituent at the 5-position of the thiazole ring governs whether the active site of the enzyme is occupied by one or two inhibitor molecules. Moreover, this substituent plays a critical role in determining the affinity, improving it from >700 to 1.5 nM in the best binder. These structures lay the groundwork for future modifications that would result in even tighter binding and the correct placement of moieties that confer favorable pharmacodynamics and pharmacokinetic properties.

A SPECT imager with synthetic collimation

This work outlines the development of a multi-pinhole SPECT system designed to produce a synthetic-collimator image of a small field of view. The focused multi-pinhole collimator was constructed using rapid-prototyping and casting techniques. The collimator projects the field of view through forty-six pinholes when the detector is adjacent to the collimator. The detector is then moved further from the collimator to increase the magnification of the system. The amount of pinhole-projection overlap increases with the system magnification. There is no rotation in the system; a single tomographic angle is used in each system configuration. The maximum-likelihood expectation-maximization (MLEM) algorithm is implemented on graphics processing units to reconstruct the object in the field of view. Iterative reconstruction algorithms, such as MLEM, require an accurate model of the system response. For each system magnification, a sparsely-sampled system response is measured by translating a point source through a grid encompassing the field of view. The pinhole projections are individually identified and associated with their respective apertures. A 2D elliptical Gaussian model is applied to the pinhole projections on the detector. These coefficients are associated with the object-space location of the point source, and a finely-sampled system matrix is interpolated. Simulations with a hot-rod phantom demonstrate the efficacy of combining low-resolution non-multiplexed data with high-resolution multiplexed data to produce high-resolution reconstructions.

Palladium(III)-catalyzed fluorination of arylboronic acid derivatives

A practical, palladium-catalyzed synthesis of aryl fluorides from arylboronic acid derivatives is presented. The reaction is operationally simple and amenable to multigram-scale synthesis. Evaluation of the reaction mechanism suggests a single-electron-transfer pathway, involving a Pd(III) intermediate that has been isolated and characterized.

Development of new deoxycytidine kinase inhibitors and noninvasive in vivo evaluation using positron emission tomography

Combined inhibition of ribonucleotide reductase and deoxycytidine kinase (dCK) in multiple cancer cell lines depletes deoxycytidine triphosphate pools leading to DNA replication stress, cell cycle arrest, and apoptosis. Evidence implicating dCK in cancer cell proliferation and survival stimulated our interest in developing small molecule dCK inhibitors. Following a high throughput screen of a diverse chemical library, a structure-activity relationship study was carried out. Positron Emission Tomography (PET) using (18)F-L-1-(2'-deoxy-2'-FluoroArabinofuranosyl) Cytosine ((18)F-L-FAC), a dCK-specific substrate, was used to rapidly rank lead compounds based on their ability to inhibit dCK activity in vivo. Evaluation of a subset of the most potent compounds in cell culture (IC50 = ∼1-12 nM) using the (18)F-L-FAC PET pharmacodynamic assay identified compounds demonstrating superior in vivo efficacy.

Design and performance of a small-animal imaging system using synthetic collimation

This work outlines the design and construction of a single-photon emission computed tomography imaging system based on the concept of synthetic collimation. A focused multi-pinhole collimator is constructed using rapid-prototyping and casting techniques. The collimator projects the centre of the field of view (FOV) through 46 pinholes when the detector is adjacent to the collimator, with the number reducing towards the edge of the FOV. The detector is then moved further from the collimator to increase the magnification of the system. The object distance remains constant, and each new detector distance is a new system configuration. The level of overlap of the pinhole projections increases as the system magnification increases, but the number of projections subtended by the detector is reduced. There is no rotation in the system; a single tomographic angle is used in each system configuration. Image reconstruction is performed using maximum-likelihood expectation-maximization and an experimentally measured system matrix. The system matrix is measured for each configuration on a coarse grid, using a point source. The pinholes are individually identified and tracked, and a Gaussian fit is made to each projection. The coefficients of these fits are used to interpolate the system matrix. The system is validated experimentally with a hot-rod phantom. The Fourier crosstalk matrix is also measured to provide an estimate of the average spatial resolution along each axis over the entire FOV. The 3D synthetic-collimator image is formed by estimating the activity distribution within the FOV and summing the activities in the voxels along the axis perpendicular to the collimator face.

Psychosocial stressors and the prognosis of major depression: a test of Axis IV

BACKGROUND

Axis IV is for reporting 'psychosocial and environmental problems that may affect the diagnosis, treatment and prognosis of mental disorders'. No studies have examined the prognostic value of Axis IV in DSM-IV.

METHOD

We analyzed data from 2497 participants in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) with major depressive episode (MDE). We hypothesized that psychosocial stressors predict a poor prognosis of MDE. Secondarily, we hypothesized that psychosocial stressors predict a poor prognosis of anxiety and substance use disorders. Stressors were defined according to DSM-IV's taxonomy, and empirically using latent class analysis (LCA).

RESULTS

Primary support group problems, occupational problems and childhood adversity increased the risks of depressive episodes and suicidal ideation by 20-30%. Associations of the empirically derived classes of stressors with depression were larger in magnitude. Economic stressors conferred a 1.5-fold increase in risk for a depressive episode [95% confidence interval (CI) 1.2-1.9]; financial and interpersonal instability conferred a 1.3-fold increased risk of recurrent depression (95% CI 1.1-1.6). These two classes of stressors also predicted the recurrence of anxiety and substance use disorders. Stressors were not related to suicidal ideation independent from depression severity.

CONCLUSIONS

Psychosocial and environmental problems are associated with the prognosis of MDE and other Axis I disorders. Although DSM-IV's taxonomy of stressors stands to be improved, these results provide empirical support for the prognostic value of Axis IV. Future work is needed to determine the reliability of Axis IV assessments in clinical practice, and the usefulness of this information to improving the clinical course of mental disorders.

Potential role of mesenchymal stem cells (MSCs) in the breast tumour microenvironment: stimulation of epithelial to mesenchymal transition (EMT)

Bone marrow-derived mesenchymal stem cells (MSCs) are known to specifically migrate to and engraft at tumour sites. Understanding interactions between cancer cells and MSCs has become fundamental to determining whether MSC-tumour interactions should be harnessed for delivery of therapeutic agents or considered a target for intervention. Breast Cancer Cell lines (MDA-MB-231, T47D & SK-Br3) were cultured alone or on a monolayer of MSCs, and retrieved using epithelial specific magnetic beads. Alterations in expression of 90 genes associated with breast tumourigenicity were analysed using low-density array. Expression of markers of epithelial-mesenchymal transition (EMT) and array results were validated using RQ-PCR. Co-cultured cells were analysed for changes in protein expression, growth pattern and morphology. Gene expression and proliferation assays were also performed on indirect co-cultures. Following direct co-culture with MSCs, breast cancer cells expressed elevated levels of oncogenes (NCOA4, FOS), proto-oncogenes (FYN, JUN), genes associated with invasion (MMP11), angiogenesis (VEGF) and anti-apoptosis (IGF1R, BCL2). However, universal downregulation of genes associated with proliferation was observed (Ki67, MYBL2), and reflected in reduced ATP production in response to MSC-secreted factors. Significant upregulation of EMT specific markers (N-cadherin, Vimentin, Twist and Snail) was also observed following co-culture with MSCs, with a reciprocal downregulation in E-cadherin protein expression. These changes were predominantly cell contact mediated and appeared to be MSC specific. Breast cancer cell morphology and growth pattern also altered in response to MSCs. MSCs may promote breast cancer metastasis through facilitation of EMT.