Grant Dagliyan

The in vivo effect of propranolol on cerebral perfusion and hypoxia after traumatic brain injury.

BACKGROUND Recent epidemiologic evidence has identified beta-blockade as independently associated with improved survival in patients with isolated traumatic brain injury (TBI). Reduced sympathetic discharge and catecholamine release may improve circulation in the injured areas and influence delayed demise. The purpose of this study was to investigate the cerebral effect of beta-blockade in a murine TBI model using immunohistochemical and microPET analysis. METHODS Balb/c mice underwent TBI as in a previously described model and were randomized to receive treatment with propranolol or placebo in a blinded fashion. Immunofluorescent images were obtained for vessel density (CD31), vessel perfusion (Ricinus communis agglutinin [RCA]-lectin), and cerebral hypoxia (hypoxyprobe-1) and compared by digital quantification. Perfusion measurements were acquired using positron emission tomography microPET scans with [64Cu]-pyruvaldehyde bis(N4-methylthiosemicarbazone) ([64Cu]-PTSM) and converted into standardized uptake values (SUV) for analysis. RESULTS On immunohistochemical analysis, the normal mouse cerebral perfusion was a quantitated mean of 325 +/- 20, the cerebral perfusion after TBI and treatment with placebo was 113 +/- 25, and the cerebral perfusion after TBI treated with propranolol was 172 +/- 23. Immunohistochemical analysis demonstrated treatment with propranolol improved cerebral perfusion by 152% (p value <0.01) and reduced cerebral hypoxia by 24.2% (p value <0.01) compared with treatment with placebo. MicroPET imaging of the normal mouse brain after injection with placebo measured a SUV of 0.7075 +/- 0.02; the normal mouse brain after treatment with propranolol measured a SUV of 0.400 +/- 0.02. After TBI and treatment with placebo, the SUV reduced to 0.395 +/- 0.01; after treatment with propranolol the SUV measured 0.515 +/- 0.04. MicroPET imaging demonstrated propranolol improved cerebral perfusion after TBI to 130% of placebo (p value <0.01). CONCLUSION Propranolol in vivo increased cerebral perfusion and decreased cerebral hypoxia. This research demonstrates beta-blockade may prevent additional brain damage after traumatic insult and should be the focus of future clinical trials.

Induced T regulatory cells suppress osteoclastogenesis and bone erosion in collagen-induced arthritis better than natural T regulatory cells

Background Although natural regulatory T cells (nTregs) can suppress osteoclastogenesis, the role of TGF-β-induced CD4+Foxp3+ Tregs (iTregs) in osteoclastogenesis remains unknown. Objective To determine the effects of iTregs on osteoclastogenesis in vitro and on bone erosion in vivo in collagen-induced arthritis (CIA). Methods Osteoclastogenesis was induced in bone marrow CD11b+ cells with receptor activator of nuclear factor κ B (NF-κB) ligand (RANKL) and macrophage colony stimulating factor. Graded doses of Tregs were added to inhibit osteoclastogenesis. Transwell and antibody blockade experiments were performed to assess the roles for cell contact and soluble cytokines. NF-κB activation was determined by western blot. iTregs or nTregs were adoptively transferred to mice with CIA to assess in vivo effects on disease incidence and bone erosion, the latter determined by CT scanning. Results Both nTregs and iTregs greatly suppressed osteoclastogenesis in vitro, but only iTregs sustained this effect when interleukin-6 was present. iTregs, but not nTregs, significantly suppressed development of CIA. Bone erosions in iTregs-treated mice were diminished compared with untreated mice or nTregs-treated mice. Treatment with iTregs, but not with nTregs, dramatically decreased NF-κB p65/p50 levels in osteoclasts in vitro and p65/50 and RANKL expression by synovial tissues in vivo. Conclusion iTregs may be therapeutically beneficial in rheumatoid arthritis and related diseases associated with bone erosions.

A Nanoscale Tool for Photoacoustic-Based Measurements of Clotting Time and Therapeutic Drug Monitoring of Heparin

Heparin anticoagulation therapy is an indispensable feature of clinical care yet has a narrow therapeutic window and is the second most common intensive care unit (ICU) medication error. The active partial thromboplastin time (aPTT) monitors heparin but suffers from long turnaround times, a variable reference range, limited utility with low molecular weight heparin, and poor correlation to dose. Here, we describe a photoacoustic imaging technique to monitor heparin concentration using methylene blue as a simple and Federal Drug Administration-approved contrast agent. We found a strong correlation between heparin concentration and photoacoustic signal measured in phosphate buffered saline (PBS) and blood. Clinically relevant heparin concentrations were detected in blood in 32 s with a detection limit of 0.28 U/mL. We validated this imaging approach by correlation to the aPTT (Pearsons r = 0.86; p < 0.05) as well as with protamine sulfate treatment. This technique also has good utility with low molecular weight heparin (enoxaparin) including a blood detection limit of 72 μg/mL. We then used these findings to create a nanoparticle-based hybrid material that can immobilize methylene blue for potential applications as a wearable/implantable heparin sensor to maintain drug levels in the therapeutic window. To the best of our knowledge, this is the first use of photoacoustics to image anticoagulation therapy with significant potential implications to the cardiovascular and surgical community.

In vivo effect of propranolol dose and timing on cerebral perfusion after traumatic brain injury.

BACKGROUND In vivo models of traumatic brain injury (TBI) demonstrate increased cerebral perfusion, decreased cerebral hypoxia, reduced cerebral edema, and improved neurologic recovery with propranolol administration. The purpose of this study was to determine the effect of different propranolol doses and timing on cerebral perfusion in a murine TBI model. METHODS Fifteen minutes after TBI, three groups of mice (four mice per group) were randomized to receive intravenous injections of placebo, 4 mg/kg propranolol, or 1 mg/kg propranolol. Two delayed treatment groups were randomized to receive placebo or 4 mg/kg propranolol 60 minutes after TBI. Cerebral perfusion was then imaged by micropositron emission tomography. RESULTS With placebo injection 15 minutes after TBI, the standard uptake value (SUV) mean was 0.395 +/- 0.01; with 4 mg/kg propranolol, the SUV mean was 0.515 +/- 0.04; and with 1 mg/kg propranolol, the SUV mean was 0.46 +/- 0.01. Animals receiving 4 mg/kg propranolol demonstrated significant improvement (p < 0.01) in cerebral perfusion compared with placebo and compared with 1 mg/kg propranolol. With placebo injection at 60 minutes after TBI, the SUV mean was 0.26 +/- 0.03; and with 4 mg/kg propranolol, the SUV mean was 0.43 +/- 0.02. After 60 minutes, animals receiving 4 mg/kg propranolol demonstrated significant improvement (p < 0.01) in cerebral perfusion compared with placebo. CONCLUSION In a murine model of TBI, higher doses of propranolol were preferable to lower doses and both early and late propranolol administration improved cerebral perfusion. Potential mechanisms and therapeutic potential require further research.

β-adrenergic receptor inhibition affects cerebral glucose metabolism, motor performance, and inflammatory response after traumatic brain injury.

BACKGROUND The purpose of this study was to evaluate how &bgr;-adrenergic receptor inhibition after traumatic brain injury (TBI) alters changes in early cerebral glucose metabolism and motor performance, as well as cerebral cytokine and heat shock protein (HSP) expression. METHODS Mouse cerebral glucose metabolism was measured by microPET fluorodeoxyglucose uptake and converted into standardized uptake values (SUV). Four groups of C57/Bl6 mice (wild type [WT]) were initially evaluated: sham or TBI, followed by tail vein injection of either saline or a nonselective &bgr;-adrenergic receptor inhibitor (propranolol, 4 mg/kg). Then motor performance, cerebral cytokine, and HSP70 expression were studied at 12 hours and 24 hours after sham injury or TBI in WT mice treated with saline or propranolol and in &bgr;1-adrenergic/&bgr;2-adrenergic receptor knockout (BARKO) mice treated with saline. RESULTS Cerebral glucose metabolism was significantly reduced after TBI (mean SUV TBI, 1.63 vs. sham 1.97, p < 0.01) and propranolol attenuated this reduction (mean SUV propranolol, 1.89 vs. saline 1.63, p < 0.01). Both propranolol and BARKO reduced motor deficits at 24 hours after injury, but only BARKO had an effect at 12 hours after injury. TBI WT mice treated with saline performed worse than propranolol mice at 24 hours after injury on rotarod (23 vs. 44 seconds, p < 0.01) and rearing (130 vs. 338 events, p = 0.01) results. At 24 hours after injury, sham BARKO and TBI BARKO mice were similar on rotarod (21 vs. 19 seconds, p = 0.53), ambulatory testing (2,891 vs. 2,274 events, p = 0.14), and rearing (129 vs. 64 events, p = 0.09) results. Interleukin 1&bgr; expression was affected by BARKO and propranolol after TBI; attenuation of interleukin 6 and increased HSP70 expression were noted only with BARKO. CONCLUSION &bgr;-adrenergic receptor inhibition affects cerebral glucose metabolism, motor performance, as well as cerebral cytokine and HSP expression after TBI. (J Trauma Acute Care Surg. 2012;73: 33–40. Copyright

A DICOM-based 2nd generation molecular imaging data grid implementing the IHE XDS-i integration profile

PurposeA Molecular Imaging Data Grid (MIDG) was developed to address current informatics challenges in archival, sharing, search, and distribution of preclinical imaging studies between animal imaging facilities and investigator sites. This manuscript presents a 2nd generation MIDG replacing the Globus Toolkit with a new system architecture that implements the IHE XDS-i integration profile. Implementation and evaluation were conducted using a 3-site interdisciplinary test-bed at the University of Southern California.MethodsThe 2nd generation MIDG design architecture replaces the initial design’s Globus Toolkit with dedicated web services and XML-based messaging for dedicated management and delivery of multi-modality DICOM imaging datasets. The Cross-enterprise Document Sharing for Imaging (XDS-i) integration profile from the field of enterprise radiology informatics was adopted into the MIDG design because streamlined image registration, management, and distribution dataflow are likewise needed in preclinical imaging informatics systems as in enterprise PACS application. Implementation of the MIDG is demonstrated at the University of Southern California Molecular Imaging Center (MIC) and two other sites with specified hardware, software, and network bandwidth.ResultsEvaluation of the MIDG involves data upload, download, and fault-tolerance testing scenarios using multi-modality animal imaging datasets collected at the USC Molecular Imaging Center. The upload, download, and fault-tolerance tests of the MIDG were performed multiple times using 12 collected animal study datasets. Upload and download times demonstrated reproducibility and improved real-world performance. Fault-tolerance tests showed that automated failover between Grid Node Servers has minimal impact on normal download times.ConclusionsBuilding upon the 1st generation concepts and experiences, the 2nd generation MIDG system improves accessibility of disparate animal-model molecular imaging datasets to users outside a molecular imaging facility’s LAN using a new architecture, dataflow, and dedicated DICOM-based management web services. Productivity and efficiency of preclinical research for translational sciences investigators has been further streamlined for multi-center study data registration, management, and distribution.

Performance comparison of GENISYS4 and microPET preclinical PET scanners

Genisys4 is a new preclinical positron emission tomography (PET) scanner, which consists of four detector panels. Due to its unique design, the performance characteristics of the system is different from the conventional multiple detector ring preclinical PET scanners. In this paper, we compare the performance of the four-panel Genisys4 with two ring-geometry scanners: microPET R4 and Inveon. For this purpose, a NEMA NU 4-2008 image quality phantom and two mice injected with 18F-FDG were scanned. The results will aid investigators in using the appropriate PET scanner for their preclinical studies.

Comparative musculoskeletal anatomy of chameleon limbs, with implications for the evolution of arboreal locomotion in lizards and for teratology

Chameleon species have recently been adopted as models for evo‐devo and macroevolutionary processes. However, most anatomical and developmental studies of chameleons focus on the skeleton, and information about their soft tissues is scarce. Here, we provide a detailed morphological description based on contrast enhanced micro‐CT scans and dissections of the adult phenotype of all the forelimb and hindlimb muscles of the Veiled Chameleon (Chamaeleo calyptratus) and compare these muscles with those of other chameleons and lizards. We found the appendicular muscle anatomy of chameleons to be surprisingly conservative considering the remarkable structural and functional modifications of the limb skeleton, particularly the distal limb regions. For instance, the zygodactyl autopodia of chameleons are unique among tetrapods, and the carpals and tarsals are highly modified in shape and number. However, most of the muscles usually present in the manus and pes of other lizards are present in the same configuration in chameleons. The most obvious muscular features related to the peculiar opposable autopodia of chameleons are: (1) presence of broad, V‐shaped plantar and palmar aponeuroses, and absence of intermetacarpales and intermetatarsales, between the digits separated by the cleft in each autopod; (2) oblique orientation of the superficial short flexors originating from these aponeuroses, which may allow these muscles to act as powerful adductors of the “super‐digits”; and (3) well‐developed abductor digiti minimi muscles and abductor pollicis/hallucis brevis muscles, which may act as powerful abductors of the “super‐digits.”

A virtualized infrastructure for molecular imaging research using a data grid model

The animal-to-researcher workflow in many of todays small animal imaging center is burdened with proprietary data limitations, inaccessible back-up methods, and imaging results that are not easily viewable across campus. Such challenges decrease the amount of scans performed per day at the center and requires researchers to wait longer for their images and quantified results. Furthermore, data mining at the small animal imaging center is often limited to researcher names and date-labelled archiving hard-drives. To gain efficiency and reliable access to small animal imaging data, such a center needs to move towards an integrated workflow with file format normalization services, metadata databases, expandable archiving infrastructure, and comprehensive user interfaces for query / retrieval tools - achieving all in a cost-effective manner. This poster presentation demonstrates how grid technology can support such a molecular imaging and small animal imaging research community to bridge the needs between imaging modalities and clinical researchers. Existing projects have utilized the Data Grid in PACS tier 2 backup solutions, where fault-tolerance is a high priority, as well as imagingbased clinical trials where data security and auditing are primary concerns. Issues to be addressed include, but are not limited to, novel database designs, file format standards, virtual archiving and distribution workflows, and potential grid computing for 3-D reconstructions, co-registration, and post-processing analysis.