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Purpose: In this study, we compared two triarylmethyl (TAM) spin probes, Ox071 and Ox063 for their efficacy in measuring tissue oxygen levels under hypoxic and normoxic conditions by R 2 *-based EPR oximetry., Methods: The R 2 * dependencies on the spin probe concentration and oxygen level were calibrated using deoxygenated 1, 2, 5, and 10 mM standard solutions and 2 mM solutions saturated at 0%, 2%, 5%, 10%, and 21% of oxygen. For the hypoxic model, in vivo imaging of a MIA PaCa-2 tumor implanted in the hind leg of a mouse was performed on successive days by R 2 *-based EPR oximetry using either Ox071 or Ox063. For the normoxic model, renal imaging of healthy athymic mice was performed using both spin probes. The 3D images were reconstructed by single point imaging and multi-gradient technique was used to determine R 2 * maps., Results: The signal intensities of Ox071 were approximately three times greater than that of Ox063 in the entire partial pressure of oxygen (pO 2 ) range investigated. The histograms of the tumor pO 2 images were skewed for both spin probes, and Ox071 showed more frequency counts at pO 2  > 32 mm Hg. In the normoxic kidney model, there was a clear delineation between the high pO 2 cortex and the low pO 2 medulla regions. The histogram of high-resolution kidney oximetry image using Ox071 was nearly symmetrical and frequency counts were seen up to 55 mm Hg, which were missed in Ox063 imaging., Conclusion: As an oximetric probe, Ox071 has clear advantages over Ox063 in terms of sensitivity and the pO 2 dynamic range., (Published 2023. This article is a U.S. Government work and is in the public domain in the USA.)

Aims: Pancreatic ductal adenocarcinomas (PDACs) form hypovascular and hypoxic tumors, which are difficult to treat with current chemotherapy regimens. Gemcitabine (GEM) is often used as a first-line treatment for PDACs but has issues with chemoresistance and penetration in the interior of the tumor. Evofosfamide, a hypoxia-activated prodrug, has been shown to be effective in combination with GEM, although the mechanism of each drug on the other has not been established. We used mouse xenografts from two cell lines (MIA Paca-2 and SU.86.86) with different tumor microenvironmental characteristics to probe the action of each drug on the other. Results: GEM treatment enhanced survival times in mice with SU.86.86 leg xenografts (hazard ratio [HR] = 0.35, p  = 0.03) but had no effect on MIA Paca-2 mice (HR = 0.91, 95% confidence interval = 0.37-2.25, p  = 0.84). Conversely, evofosfamide did not improve survival times in SU.86.86 mice to a statistically significant degree (HR = 0.57, p  = 0.22). Electron paramagnetic resonance imaging showed that oxygenation worsened in MIA Paca-2 tumors when treated with GEM, providing a direct mechanism for the activation of the hypoxia-activated prodrug evofosfamide by GEM. Sublethal amounts of either treatment enhanced the toxicity of other treatment in vitro in SU.86.86 but not in MIA Paca-2. By the biomarker γH2AX, combination treatment increased the number of double-stranded DNA lesions in vitro for SU.86.86 but not MIA Paca-2. Innovation and Conclusion: The synergy between GEM and evofosfamide appears to stem from the dual action of GEMs effect on tumor vasculature and inhibition by GEM of the homologous recombination DNA repair process. Antioxid. Redox Signal. 39, 432-444.

Reoxygenation has a significant impact on the tumor response to radiotherapy. With developments in radiotherapy technology, the relevance of the reoxygenation phenomenon in treatment efficacy has been a topic of interest. Evaluating the reoxygenation in the tumor microenvironment throughout the course of radiation therapy is important in developing effective treatment strategies. In the current study, we used electron paramagnetic resonance imaging (EPRI) to directly map and quantify the partial oxygen pressure (pO 2 ) in tumor tissues. Human colorectal cancer cell lines, HT29 and HCT116, were used to induce tumor growth in female athymic nude mice. Tumors were irradiated with 3, 10, or 20 Gy using an x-ray irradiator. Prior to each EPRI scan, magnetic resonance imaging (MRI) was performed to obtain T2-weighted anatomical images for reference. The differences in the mean pO 2 were determined through two-tailed Student's t-test and one-way analysis of variance. The median pO 2 60 min after irradiation was found to be lower in HCT116 than in HT29 (9.1 ± 1.5 vs. 14.0 ± 1.0 mmHg, p = 0.045). There was a tendency for delayed and incomplete recovery of pO 2 in the HT29 tumor when a higher dose of irradiation (10 and 20 Gy) was applied. Moreover, there was a dose-dependent increase in the hypoxic areas (pO 2  < 10 mmHg) 2 and 24 h after irradiation in all groups. In addition, an area that showed pO 2 fluctuation between hypoxia and normoxia (pO 2  > 10 mmHg) was also identified surrounding the region with stable hypoxia, and it slightly enlarged after recovery from acute hypoxia. In conclusion, we demonstrated the reoxygenation phenomenon in an in vivo xenograft model study using EPRI. These findings may lead to new knowledge regarding the reoxygenation process and possibilities of a new radiation therapy concept, namely, reoxygenation-based radiation therapy., (© 2022 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.)

Purpose: PEGylated human hyaluronidase (PEGPH20) enzymatically depletes hyaluronan, an important component of the extracellular matrix, increasing the delivery of therapeutic molecules. Combinations of chemotherapy and PEGPH20, however, have been unsuccessful in Phase III clinical trials. We hypothesize that by increasing tumor oxygenation by improving vascular patency and perfusion, PEGPH20 will also act as a radiosensitization agent., Experimental Design: The effect of PEGPH20 on radiation treatment was analyzed with respect to tumor growth, survival time, p0 2 , local blood volume, and the perfusion/permeability of blood vessels in a human pancreatic adenocarcinoma BxPC3 mouse model overexpressing hyaluronan synthase 3 (HAS3)., Results: Mice overexpressing HAS3 developed fast growing, radiation resistant tumors that became rapidly more hypoxic as time progressed. Treatment with PEGPH20 increased survival times when used in combination with radiation therapy, significantly more than either radiation therapy or PEGPH20 alone. In mice that overexpressed HAS3, EPR imaging showed an increase in local pO 2 that could be linked to increases in perfusion/permeability and local blood volume immediately after PEGPH20 treatment. Hyperpolarized [1- 13 C] pyruvate suggested PEGPH20 caused a metabolic shift towards decreased glycolytic flux. These effects were confined to the mice overexpressing HAS3 - no effect of PEGPH20 on survival, radiation treatment, or pO 2 was seen in wild type BxPC3 tumors., Conclusions: PEGPH20 may be useful for radiosensitization of pancreatic cancer but only in the subset of tumors with substantial hyaluronan accumulation. The response of the treatment may potentially be monitored by non-invasive imaging of the hemodynamic and metabolic changes in the tumor microenvironment., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest, (Copyright © 2022. Published by Elsevier Inc.)

The use of implantable cardioverter defibrillators (ICDs) in young women has been increasing in recent years owing to greater awareness about inherited cardiac conditions that increase the risk of sudden death. Traditional placement of ICDs in the infraclavicular region among young women often leads to visible scars, a constant prominence that causes irritation from purse or bra straps and can result in body image concerns and device-related emotional distress. In this case series, two women with long QT syndrome required placement of ICDs for prevention of sudden cardiac death. Submammary placement of ICDs was performed in collaboration with electrophysiologists. We describe our local experience and technique in submammary placement of ICDs as well as the challenges faced., (Copyright: © Singapore Medical Association.)

Significance: Oxygen imaging techniques, which can probe the spatiotemporal heterogeneity of tumor oxygenation, could be of significant clinical utility in radiation treatment planning and in evaluating the effectiveness of hypoxia-activated prodrugs. To fulfill these goals, oxygen imaging techniques should be noninvasive, quantitative, and capable of serial imaging, as well as having sufficient temporal resolution to detect the dynamics of tumor oxygenation to distinguish regions of chronic and acute hypoxia. Recent Advances: No current technique meets all these requirements, although all have strengths in certain areas. The current status of positron emission tomography (PET)-based hypoxia imaging, oxygen-enhanced magnetic resonance imaging (MRI), 19 F MRI, and electron paramagnetic resonance (EPR) oximetry are reviewed along with their strengths and weaknesses for planning hypoxia-guided, intensity-modulated radiation therapy and detecting treatment response for hypoxia-targeted prodrugs. Critical Issues: Spatial and temporal resolution emerges as a major concern for these areas along with specificity and quantitative response. Although multiple oxygen imaging techniques have reached the investigative stage, clinical trials to test the therapeutic effectiveness of hypoxia imaging have been limited. Future Directions: Imaging elements of the redox environment besides oxygen by EPR and hyperpolarized MRI may have a significant impact on our understanding of the basic biology of the reactive oxygen species response and may extend treatment possibilities.

Background: Microglia are associated with neuroinflammation, which play a key role in the pathogenesis of neurodegenerative diseases. It has been reported that some quinazolines and quinazolinones possess anti-inflammatory properties. However, the pharmacological properties of certain quinazoline derivatives are still unknown., Objective: The antioxidant, cytotoxic, and protective effects of a series of synthesized 2- trifluoromethylquinazolines (2, 4, and 5) and quinazolinones (6-8) in lipopolysaccharide (LPS)- murine microglia (BV2) and hydrogen peroxide (H 2 O 2 )-mouse neuroblastoma-2a (N2a) cells were investigated., Method: The antioxidant activity of synthesized compounds was evaluated with ABTS and DPPH assays. The cytotoxic activities were determined by MTS assay in BV2 and N2a cells. The production of nitric oxide (NO) in LPS-induced BV2 microglia cells was quantified., Results: The highest ABTS and DPPH scavenging activities were observed for compound 8 with 87.7% of ABTS scavenge percentage and 54.2% DPPH inhibition. All compounds were noncytotoxic in BV2 and N2a cells at 5 and 50 μg/mL. The compounds which showed the highest protective effects in LPS-induced BV2 and H 2 O 2 -induced N2a cells were 5 and 7. All tested compounds, except 4, also reduced NO production at concentrations of 50 μg/mL. The quinazolinone series 6-8 exhibited the highest percentage of NO reduction, ranging from 38 to 60%. Compounds 5 and 8 possess balanced antioxidant and protective properties against LPS- and H 2 O 2 -induced cell death, thus showing great potential to be developed into anti-inflammatory and neuroprotective agents., Conclusion: Compounds 5 and 7 were able to protect the BV2 and N2a cells against LPS and H 2 O 2 toxicity, respectively, at a low concentration (5 μg/mL). Compounds 6-8 showed potent reduction of NO production in BV2 cells., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Molecular imaging approaches for metabolic and physiologic imaging of tumors have become important for treatment planning and response monitoring. However, the relationship between the physiologic and metabolic aspects of tumors is not fully understood. Here, we developed new hyperpolarized MRI and electron paramagnetic resonance imaging procedures that allow more direct assessment of tumor glycolysis and oxygenation status quantitatively. We investigated the spatial relationship between hypoxia, glucose uptake, and glycolysis in three human pancreatic ductal adenocarcinoma tumor xenografts with differing physiologic and metabolic characteristics. At the bulk tumor level, there was a strong positive correlation between 18 F-FDG-PET and lactate production, while pO 2 was inversely related to lactate production and 18 F-2-fluoro-2-deoxy-D-glucose ( 18 F-FDG) uptake. However, metabolism was not uniform throughout the tumors, and the whole tumor results masked different localizations that became apparent while imaging. 18 F-FDG uptake negatively correlated with pO 2 in the center of the tumor and positively correlated with pO 2 on the periphery. In contrast to pO 2 and 18 F-FDG uptake, lactate dehydrogenase activity was distributed relatively evenly throughout the tumor. The heterogeneity revealed by each measure suggests a multimodal molecular imaging approach can improve tumor characterization, potentially leading to better prognostics in cancer treatment. SIGNIFICANCE: Novel multimodal molecular imaging techniques reveal the potential of three interrelated imaging biomarkers to profile the tumor microenvironment and interrelationships of hypoxia, glucose uptake, and glycolysis., (©2020 American Association for Cancer Research.)

Cordyceps militaris is known for its curative properties. The present study was undertaken to evaluate the reduction of nitric oxide production by BV2 cells by the bioactive fraction of stroma powder of C. militaris, and to deduce the potential chemical components and pathways that may be responsible. The CE2 fraction from ethyl acetate extract did not exert any cytotoxic effects toward the BV2 cells at concentrations 0.1 to 100 μg/mL. The CE2 fraction also showed a significant (p < 0.05) reduction in nitric oxide production at 1-100 μg/mL. At 10 μg/mL, the CE2 fraction attenuated 85% of the NO production in BV2 cells. Further, the CE2 fraction (10 μg/mL) downregulated inflammatory genes, iNOS and COX-2, and upregulated anti-inflammatory genes, HO-1 and NQO-1. The CE2 fraction reduced NO production via activation of NRF2 and NF-κB transcriptions. The chemical constituents of the bioactive CE2 fraction were identified via GCMS. Eleven lipid components were identified including fatty acids, fatty acid esters, and sterols.

The study explores biogenic nitrogen doped carbon microspheres derived from resorcinol, formaldehyde (BNCMs), for battery application. Ureolytic bacteria were used to produce biogenic ammonia in the form of ammonium carbonate and ammonium bicarbonate. Copolymerization of resorcinol, formaldehyde and biogenic ammonia at 60-80 °C produces BNCMs. Elemental analysis evidences that the nitrogen-enriched carbon microspheres contain about 8% of nitrogen. The BNCMs anode exhibits appreciable reversible capacity and excellent rate performance in lithium ion batteries (LIBs) and sodium ion batteries (SIBs). In the case of LIBs, BNCMs anode exhibits an excellent stable specific capacity of 580 mAh g -1 with 97% of capacity retention even after 100 cycles without any significant capacity fading. Similarly, the observed capacity is as 102 mAh g -1 for 1000 cycles at a high rate current density of 1 A g -1 without any considerable capacity fade. In SIBs, BNCMs anode delivers a specific discharge and charge capacity of 405 and 195 mAh g -1 respectively. Further, prolonged cycles BNCMs anode exhibits a steady state progressive capacity of 170 mAh g -1 even after 100 cycles with steady state capacity. BNCMs thus evidence its suitability as high performance anode material for both LIBs and SIBs., (Copyright © 2019 Elsevier Inc. All rights reserved.)

An excessive RF power requirement is one of the main obstacles in the clinical translation of EPR imaging. The radio frequency (RF) pulses used in EPR imaging to excite electron spins must be very short to match their fast relaxation. With traditional pulse schemes and ninety degree flip angles, this can lead to either unsafe specific absorption rate (SAR) levels or unfeasibly long repetition times. In spectroscopy experiments, it has been shown that stochastic excitation and correlation detection can reduce the power while maintaining sensitivity but have yet to be applied to imaging experiments. Stochastic excitation is implemented using a pseudo-random phase modulation of the input stimulus. Using a crossed coil resonator assembly comprised of an outer saddle coil and an inner surface coil, it was possible to obtain a minimum isolation of ∼50 dB across a 12 MHz bandwidth. An incident peak RF power of 5 mW was used to excite the system. The low background signal obtained from this resonator allowed us to generate images with 32 dB (>1000:1) signal-to-noise ratio (SNR) while exciting with a traditional pulse sequence in a phantom containing the solid paramagnetic probe NMP-TCNQ (N-methyl pyridinium tetracyanoquinodimethane). Using two different stochastic excitation schemes, we were able to achieve a greater than 4-fold increase in SNR at the same peak power and number of averages, compared to single pulse excitation. This procedure allowed imaging at significantly lower RF power levels than used in conventional EPR imaging system configurations. Similar techniques may enable clinical applications for EPR imaging by facilitating the use of larger RF coils while maintaining a safe SAR level., (Published by Elsevier Inc.)

Purpose: Spin-lattice relaxation rate (R 1 )-based time-domain EPR oximetry is reported for in vivo applications using a paramagnetic probe, a trityl-based Oxo71., Methods: The R 1 dependence of the trityl probe Oxo71 on partial oxygen pressure (pO 2 ) was assessed using single-point imaging mode of spatial encoding combined with rapid repetition, similar to T 1 -weighted MRI, for which R 1 was determined from 22 repetition times ranging from 2.1 to 40.0 μs at 300 MHz. The pO 2 maps of a phantom with 3 tubes containing 2 mM Oxo71 solutions equilibrated at 0%, 2%, and 5% oxygen were determined by R 1 and apparent spin-spin relaxation rate ( R2*) simultaneously., Results: The pO 2 maps derived from R 1 and R2* agreed with the known pO 2 levels in the tubes of Oxo71. However, the histograms of pO 2 revealed that R 1 offers better pO 2 resolution than R2* in low pO 2 regions. The SDs of pixels at 2% pO 2 (15.2 mmHg) were about 5 times lower in R 1 -based estimation than R2*-based estimation (mean ± SD: 13.9 ± 1.77 mmHg and 18.3 ± 8.70 mmHg, respectively). The in vivo pO 2 map obtained from R 1 -based assessment displayed a homogeneous profile in low pO 2 regions in tumor xenografts, consistent with previous reports on R2*-based oximetric imaging. The scan time to obtain the R 1 map can be significantly reduced using 3 repetition times ranging from 4.0 to 12.0 μs., Conclusion: Using the single-point imaging modality, R 1 -based oximetry imaging with useful spatial and oxygen resolutions for small animals was demonstrated., (© 2018 International Society for Magnetic Resonance in Medicine.)

Purpose: To develop an implantable wireless coil with parametric amplification capabilities for time-domain electron paramagnetic resonance (EPR) spectroscopy operating at 300 MHz., Methods: The wireless coil and lithium phthalocyanine (LiPc), a solid paramagnetic probe, were each embedded individually in a biocompatible polymer polydimethoxysiloxane (PDMS). EPR signals from the LiPc embedded in PDMS (LiPc/PDMS) were generated by a transmit-receive surface coil tuned to 300 MHz. Parametric amplification was configured with an external pumping coil tuned to 600 MHz and placed between the surface coil resonator and the wireless coil., Results: Phantom studies showed significant enhancement in signal to noise using the pumping coil. However, no influence of the pumping coil on the oxygen-dependent EPR spectral linewidth of LiPc/PDMS was observed, suggesting the validity of parametric amplification of EPR signals for oximetry by implantation of the encapsulated wireless coil and LiPc/PDMS in deep regions of live objects. In vivo studies demonstrate the feasibility of this approach to longitudinally monitor tissue pO 2 in vivo and also monitor acute changes in response to pharmacologic challenges. The encapsulated wireless coil and LiPc/PDMS engendered no host immune response when implanted for ∼3 weeks and were found to be well tolerated., Conclusions: This approach may find applications for monitoring tissue oxygenation to better understand the pathophysiology associated with wound healing, organ transplantation, and ischemic diseases., (© 2018 International Society for Magnetic Resonance in Medicine.)

The purpose of this study is to demonstrate calcium alginate hydrogels as a system for in vitro radiobiological and metabolic studies of cancer cells. Previous studies have established calcium alginate as a versatile three-dimensional (3D) culturing system capable of generating areas of oxygen heterogeneity and modeling metabolic changes in vitro. Here, through dosimetry, clonogenic and viability assays, and pimonidazole staining, we demonstrate that alginate can model radiobiological responses that monolayer cultures do not simulate. Notably, alginate hydrogels with radii greater than 500 μm demonstrate hypoxic cores, while smaller hydrogels do not. The size of this hypoxic region correlates with hydrogel size and improved cell survival following radiation therapy. Hydrogels can also be utilized in hyperpolarized magnetic resonance spectroscopy and extracellular flux analysis. Alginate therefore offers a reproducible, consistent, and low-cost means for 3D culture of cancer cells for radiobiological studies that simulates important in vivo parameters such as regional hypoxia and enables long-term culturing and in vitro metabolic studies., (Published by Elsevier B.V.)

Pancreatic ductal adenocarcinoma (PDAC) is characterized by hypoxic niches that lead to treatment resistance. Therefore, studies of tumor oxygenation and metabolic profiling should contribute to improved treatment strategies. Here, we define two imaging biomarkers that predict differences in tumor response to therapy: (i) partial oxygen pressure (pO 2 ), measured by EPR imaging; and (ii) [1- 13 C] pyruvate metabolism rate, measured by hyperpolarized 13 C MRI. Three human PDAC xenografts with varying treatment sensitivity (Hs766t, MiaPaCa2, and Su.86.86) were grown in mice. The median pO 2 of the mature Hs766t, MiaPaCa2, and Su.86.86 tumors was 9.1 ± 1.7, 11.1 ± 2.2, and 17.6 ± 2.6 mm Hg, and the rate of pyruvate-to-lactate conversion was 2.72 ± 0.48, 2.28 ± 0.26, and 1.98 ± 0.51 per minute, respectively ( n = 6, each). These results are in agreement with steady-state data of matabolites quantified by mass spectroscopy and histologic analysis, indicating glycolytic and hypoxia profile in Hs766t, MiaPaca2, and Su.86.86 tumors. Fractionated radiotherapy (5 Gy × 5) resulted in a tumor growth delay of 16.7 ± 1.6 and 18.0 ± 2.7 days in MiaPaca2 and Su.86.86 tumors, respectively, compared with 6.3 ± 2.7 days in hypoxic Hs766t tumors. Treatment with gemcitabine, a first-line chemotherapeutic agent, or the hypoxia-activated prodrug TH-302 was more effective against Hs766t tumors (20.0 ± 3.5 and 25.0 ± 7.7 days increase in survival time, respectively) than MiaPaCa2 (2.7 ± 0.4 and 6.7 ± 0.7 days) and Su.86.86 (4.7 ± 0.6 and 0.7 ± 0.6 days) tumors. Collectively, these results demonstrate the ability of molecular imaging biomarkers to predict the response of PDAC to treatment with radiotherapy and TH-302. Significance: pO2 imaging data and clinically available metabolic imaging data provide useful insight into predicting the treatment efficacy of chemotherapy, radiation, and a hypoxia-activated prodrug as monotherapies and combination therapies in PDAC tumor xenograft models. Cancer Res; 78(14); 3783-92. ©2018 AACR ., (©2018 American Association for Cancer Research.)

Significance: Electron paramagnetic resonance imaging (EPRI) is capable of generating images of tissue oxygenation using exogenous paramagnetic probes such as trityl radicals or nitroxyl radicals. The spatial distribution of the paramagnetic probe can be generated using magnetic field gradients as in magnetic resonance imaging and, from its spectral features, spatial maps of oxygen can be obtained from live objects. In this review, two methods of signal acquisition and image formation/reconstruction are described. The probes used and its application to study tumor physiology and monitor treatment response with chemotherapy drugs in mouse models of human cancer are summarized. Recent Advances: By implementing phase encoding/Fourier reconstruction in EPRI in time domain mode, the frequency contribution to the spatial resolution was avoided and images with improved spatial resolution were obtained. The EPRI-generated pO 2 maps in tumor were useful to detect and evaluate the effects of various antitumor therapies on tumor physiology. Coregistration with other imaging modalities provided a better understanding of hypoxia-related alteration in physiology., Critical Issues: The high radiofrequency (RF) power of EPR irradiation and toxicity profile of radical probes are the main obstacles for clinical application. The improvement of RF low power pulse sequences may allow for clinical translation., Future Directions: Pulsed EPR oximetry can be a powerful tool to research various diseases involving hypoxia such as cancer, ischemic heart diseases, stroke, and diabetes. With appropriate paramagnetic probes, it can also be applied for various other purposes such as detecting local acid-base balance or oxidative stress. Antioxid. Redox Signal. 28, 1378-1393.

To examine the relationship between local oxygen partial pressure and energy metabolism in the tumor, electron paramagnetic resonance imaging (EPRI) and magnetic resonance imaging (MRI) with hyperpolarized [1- 13 C] pyruvate were performed. SCCVII and HT29 solid tumors implanted in the mouse leg were imaged by EPRI using OX063, a paramagnetic probe and 13 C-MRI using hyperpolarized [1- 13 C] pyruvate. Local partial oxygen pressure and pyruvate metabolism in the two tumor implants were examined. The effect of a single dose of 5-Gy irradiation on the pO 2 and metabolism was also investigated by sequential imaging of EPRI and 13 C-MRI in HT29 tumors. A phantom study using tubes filled with different concentration of [1- 13 C] pyruvate, [1- 13 C] lactate, and OX063 at different levels of oxygen confirmed the validity of this sequential imaging of EPRI and hyperpolarized 13 C-MRI. In vivo studies revealed SCCVII tumor had a significantly larger hypoxic fraction (pO 2 < 8 mmHg) compared to HT29 tumor. The flux of pyruvate-to-lactate conversion was also higher in SCCVII than HT29. The lactate-to-pyruvate ratio in hypoxic regions (pO 2 < 8 mmHg) 24 hours after 5-Gy irradiation was significantly higher than those without irradiation (0.76 vs. 0.36) in HT29 tumor. The in vitro study showed an increase in extracellular acidification rate after irradiation. In conclusion, co-imaging of pO 2 and pyruvate-to-lactate conversion kinetics successfully showed the local metabolic changes especially in hypoxic area induced by radiation therapy., Competing Interests: CONFLICTS OF INTEREST The authors have no potential conflicts of interest to disclose.

Edible and medicinal mushrooms are regularly used in natural medicines and home remedies since antiquity for ailments like fever, inflammation, and respiratory disorders. Lignosus rhinocerotis (Cooke) Ryvarden is a polypore found in Malaysia and other regions in South East Asia. It can be located on a spot where a tigress drips milk while feeding, hence the name "tiger's milk mushroom." The sclerotium of L. rhinocerotis is highly sought after by the native communities in Malaysia to stave off hunger, relieve cough and asthma, and provide stamina. The genomic features of L. rhinocerotis have been described. The pharmacological and toxicity effects, if any, of L. rhinocerotis sclerotium have been scientifically verified in recent years. In this review, the validated investigations including the cognitive function, neuroprotection, immune modulation, anti-asthmatic, anti-coagulation, anti-inflammatory, anti-microbial/ anti-viral, anti-obesity, anti-cancer/ anti-tumor, and antioxidant properties are highlighted. These findings suggest that L. rhinocerotis can be considered as an alternative and natural medicine in the management of non-communicable diseases. However, there is a paucity of validation studies including human clinical trials of the mycochemicals of L. rhinocerotis .

Hypoxia is considered one of the microenvironmental factors associated with the malignant nature of glioblastoma. Thus, evaluating intratumoural distribution of hypoxia would be useful for therapeutic planning as well as assessment of its effectiveness during the therapy. Electron paramagnetic resonance imaging (EPRI) is an imaging technique which can generate quantitative maps of oxygen in vivo using the exogenous paramagnetic compound, triarylmethyl and monitoring its line broadening caused by oxygen. In this study, the feasibility of EPRI for assessment of oxygen distribution in the glioblastoma using orthotopic U87 and U251 xenograft model is examined. Heterogeneous distribution of pO 2 between 0 and 50 mmHg was observed throughout the tumours except for the normal brain tissue. U251 glioblastoma was more likely to exhibit hypoxia than U87 for comparable tumour size (median pO 2 ; 29.7 and 18.2 mmHg, p = .028, in U87 and U251, respectively). The area with pO 2 under 10 mmHg on the EPR oximetry (HF10) showed a good correlation with pimonidazole staining among tumours with evaluated size. In subcutaneous xenograft model, irradiation was relatively less effective for U251 compared with U87. In conclusion, EPRI is a feasible method to evaluate oxygen distribution in the brain tumour.

Natural clays exhibit a significant degree of anisotropy in their fabric, which initially is derived from the shape of the clay platelets, deposition process and one-dimensional consolidation. Various authors have proposed anisotropic elastoplastic models involving an inclined yield surface to reproduce anisotropic behavior of plastic nature. This paper presents a novel constitutive model for soft structured clays that includes anisotropic behavior both of elastic and plastic nature. The new model incorporates stress-dependent cross-anisotropic elastic behavior within the yield surface using three independent elastic parameters because natural clays exhibit cross-anisotropic (or transversely isotropic) behavior after deposition and consolidation. Thus, the model only incorporates an additional variable with a clear physical meaning, namely the ratio between horizontal and vertical stiffnesses, which can be analytically obtained from conventional laboratory tests. The model does not consider evolution of elastic anisotropy, but laboratory results show that large strains are necessary to cause noticeable changes in elastic anisotropic behavior. The model is able to capture initial non-vertical effective stress paths for undrained triaxial tests and to predict deviatoric strains during isotropic loading or unloading.

Purpose: Electron paramagnetic resonance (EPR) imaging has evolved as a promising tool to provide non-invasive assessment of tissue oxygenation levels. Due to the extremely short T 2 relaxation time of electrons, single point imaging (SPI) is used in EPRI, limiting achievable spatial and temporal resolution. This presents a problem when attempting to measure changes in hypoxic state. In order to capture oxygen variation in hypoxic tissues and localize cycling hypoxia regions, an accelerated EPRI imaging method with minimal loss of information is needed., Methods: We present an image acceleration technique, partial Fourier compressed sensing (PFCS), that combines compressed sensing (CS) and partial Fourier reconstruction. PFCS augments the original CS equation using conjugate symmetry information for missing measurements. To further improve image quality in order to reconstruct low-resolution EPRI images, a projection onto convex sets (POCS)-based phase map and a spherical-sampling mask are used in the reconstruction process. The PFCS technique was used in phantoms and in vivo SCC7 tumor mice to evaluate image quality and accuracy in estimating O 2 concentration., Results: In both phantom and in vivo experiments, PFCS demonstrated the ability to reconstruct images more accurately with at least a 4-fold acceleration compared to traditional CS. Meanwhile, PFCS is able to better preserve the distinct spatial pattern in a phantom with a spatial resolution of 0.6mm. On phantoms containing Oxo63 solution with different oxygen concentrations, PFCS reconstructed linewidth maps that were discriminative of different O 2 concentrations. Moreover, PFCS reconstruction of partially sampled data provided a better discrimination of hypoxic and oxygenated regions in a leg tumor compared to traditional CS reconstructed images., Conclusions: EPR images with an acceleration factor of four are feasible using PFCS with reasonable assessment of tissue oxygenation. The technique can greatly enhance EPR applications and improve our understanding cycling hypoxia. Moreover this technique can be easily extended to various MRI applications., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Lignosus rhinocerotis (Cooke) Ryvarden (Tiger milk mushroom) is traditionally used to treat inflammation triggered symptoms and illnesses such as cough, fever and asthma. The present study evaluated the in vitro antioxidant, cytotoxic and anti-neuroinflammatory activities of the extract and fractions of selerotia powder of L. rhinocerotis on brain microglial (BV2) cells. The ethyl acetate fraction had a total phenolic content of 0.30 ± 0.11 mg GAE/g. This fraction had ferric reducing capacity of 61.8 ± 1.8 mg FSE/g, ABTS·+ scavenging activity of 36.8 ± 1.8 mg TE/g and DPPH free radical scavenging activity of 21.8% ± 0.7. At doses ranging from 0.1 μg/mL - 100 μg/mL, the extract and fractions were not cytotoxic to BV2 cells. At 100 μg/mL, the crude hydroethanolic extract and the ethyl acetate fraction elicited the highest nitric oxide reduction activities of 68.7% and 58.2%, respectively. Linoleic and oleic acids were the major lipid constituents in the ethyl acetate fraction based on FID and GC-MS analysis. Linoleic acid reduced nitric oxide production and down regulated the expression of neuroinflammatory iNOS and COX2 genes in BV2 cells.

Porous micro/nanostructures of earth abundant and ecobenign metals are emerging as advanced green materials for use in electrochemical energy storage devices. We present here the custom designed construction of a hybrid architecture containing porous MnO microspheres, formed out of hierarchically assembled nanoparticles using a template-free co-precipitation method, wherein the sacrificial template growth of porous spheres has been obtained by a solution mediated and time dependent oxidation strategy. The nanoporous channels in the MnO microspheres and the nanosized primary particles of MnO anodes in synergy increase the electrolyte percolation, resulting in a discharge capacity of 1200 mA h g(-1) at a current density of 50 mA g(-1) and a capacity as high as 450 mA h g(-1) under the 1000 mA g(-1) condition. The study assumes importance based on the fact that engineering of electrode materials is typically challenging, wherein design, preparation and fabrication of tailor-made electrodes with a desirable micro/nanocrystalline assembly play a critical role, especially when recommended for high capacity and high-rate applications in electrochemical energy storage devices. Further, this communication elaborates the designed construction and validation of porous MnO microspheres engineered through a time dependent process protocol as economically viable and environmentally benign anodes for lithium-ion batteries.

LiVP2O7/C, popularly known so far as an environmentally compatible and economically viable lithium battery cathode material, was exploited for the first time as an anode through the current study. LiVP2O7/C was synthesized by adopting oxalyl dihydrazide assisted solution combustion method and explored as an anode material in rechargeable lithium cell assembly. Notably, an initial capacity of 600 mAh g(-1) was exhibited by LiVP2O7/C anode, at the rate of 0.5 C along with an excellent Coulombic efficiency of 99% up to 150 cycles. The title anode demonstrates its suitability for high capacity and high rate applications by way of exhibiting appreciable capacity values of 200, 150, 120, and 110 mAh g(-1), under the influence of 2, 4, 6, and 8 C rates, respectively. Further, LiVP2O7/C anode, when subjected to a high current 10 C rate, exhibits an acceptable capacity of 107 mAh g(-1) up to 500 cycles, which is closer to its theoretical capacity value of 117 mAh g(-1). The study demonstrates the possibility of exploiting LiVP2O7/C as yet another potential anode and thereby opens a newer avenue to explore wide variety of LiMP2O7/C composites for their probable anode behavior in rechargeable lithium batteries.

Purpose: X-ray irradiation of tumors causes diverse effects on the tumor microenvironment, including metabolism. Recent developments of hyperpolarized (13)C-MRI enabled detecting metabolic changes in tumors using a tracer [1-(13)C]pyruvate, which participates in important bioenergetic processes that are altered in cancers. Here, we investigated the effects of X-ray irradiation on pyruvate metabolism in squamous cell carcinoma (SCCVII) and colon cancer (HT-29) using hyperpolarized (13)C-MRI., Experimental Design: SCCVII and HT-29 tumors were grown by injecting tumor cells into the hind legs of mice. [1-(13)C]pyruvate was hyperpolarized and injected intravenously into tumor-bearing mice, and (13)C-MR signals were acquired using a 4.7 T scanner., Results: [1-(13)C]pyruvate and [1-(13)C]lactate were detected in the tumor-bearing legs immediately after hyperpolarized [1-(13)C]pyruvate administration. The [1-(13)C]lactate to [1-(13)C]pyruvate ratio (Lac/Pyr) increased as the tumors grew in nonirradiated SCCVII tumors. The increase in Lac/Pyr was suppressed modestly with a single 10 Gy of irradiation, but it significantly decreased by further irradiation (10 Gy × 3). Similar results were obtained in HT-29; Lac/Pyr significantly dropped with fractionated 30 Gy irradiation. Independent ex vivo measurements revealed that the lactate dehydrogenase (LDH) activity and protein level were significantly smaller in the irradiated SCCVII tumors compared with the nonirradiated tumors, indicating that a decrease in LDH activity was one of the main factors responsible for the decrease of Lac/Pyr observed on (13)C-MRI., Conclusions: Robust changes of Lac/Pyr observed in the HT-29 after the radiation suggested that lactate conversion from pyruvate monitored with hyperpolarized (13)C-MRI could be useful for the evaluation of early response to radiotherapy. See related commentary by Lai et al., p. 4996., (©2015 American Association for Cancer Research.)

Different solvent extracts of Cordyceps militaris stroma powder were tested for cell viability and inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS) triggered BV2 microglia cells. Chemical investigation of the ethyl acetate fraction resulted in an enriched ergosterol sub-fraction CE3. The BV2 cells showed no cytotoxic effects when treated with the ethyl acetate fraction and sub-fraction CE3 at concentrations of 0.1 μg/mL - 100 μg/mL compared with the control. At 10 μg/mL, the ethyl acetate fraction and sub-fraction CE3 had the highest reduction of 48.0% and 44.7% of nitric oxide production, respectively. The major compound in sub-fraction CE3 was ergosterol, identified by GCMS, and the purity was checked by HPLC. Further, the reduction of nitric oxide in LPS triggered BV2 cells was about three fold higher when compared with the control commercial ergosterol.

Nutritional value of cooked food has been considered to be lower compared to the fresh produce. However, many reports showed that processed fruits and vegetables including mushrooms may retain antioxidant activity. Pleurotus spp. as one of the edible mushroom are in great demand globally and become one of the most popular mushrooms grown worldwide with 25-fold increase in production from 1960-2009. The effects of three different cooking methods (boiling, microwave and pressure cooking) on the antioxidant activities of six different types of oyster mushrooms (Pleurotus eryngii, P citrinopileatus, P. cystidiosus P. flabellatus, P. floridanus and P. pulmonarius) were assessed. Free radical scavenging (DPPH) and reducing power (TEAC) were used to evaluate the antioxidant activities and the total phenolic contents were determined by Folin-Ciocalteu reagent. Pressure cooking improved the scavenging abilities of P. floridanus (>200 %), P. flabellatus (117.6 %), and P. pulmonarius (49.1 %) compared to the uncooked samples. On the other hand, the microwaved Pleurotus eryngii showed 17 % higher in the TEAC value when compared to the uncooked sample. There was, however, no correlation between total phenolic content and antioxidant activities. There could be presence of other bioactive components in the processed mushrooms that may have contributed to the antioxidant activity. These results suggested that customized cooking method can be used to enhance the nutritional value of mushrooms and promote good health.

Purpose: Electron paramagnetic resonance imaging has surfaced as a promising noninvasive imaging modality that is capable of imaging tissue oxygenation. Due to extremely short spin-spin relaxation times, electron paramagnetic resonance imaging benefits from single-point imaging and inherently suffers from limited spatial and temporal resolution, preventing localization of small hypoxic tissues and differentiation of hypoxia dynamics, making accelerated imaging a crucial issue., Methods: In this study, methods for accelerated single-point imaging were developed by combining a bilateral k-space extrapolation technique with model-based reconstruction that benefits from dense sampling in the parameter domain (measurement of the T2 (*) decay of a free induction delay). In bilateral kspace extrapolation, more k-space samples are obtained in a sparsely sampled region by bilaterally extrapolating data from temporally neighboring k-spaces. To improve the accuracy of T2 (*) estimation, a principal component analysis-based method was implemented., Results: In a computer simulation and a phantom experiment, the proposed methods showed its capability for reliable T2 (*) estimation with high acceleration (8-fold, 15-fold, and 30-fold accelerations for 61×61×61, 95×95×95, and 127×127×127 matrix, respectively)., Conclusion: By applying bilateral k-space extrapolation and model-based reconstruction, improved scan times with higher spatial resolution can be achieved in the current single-point electron paramagnetic resonance imaging modality., (© 2014 Wiley Periodicals, Inc.)

Background: TH-302 is a hypoxia-activated prodrug (HAP) of bromo isophosphoramide mustard that is selectively activated within hypoxic regions in solid tumors. Our recent study showed that intravenously administered bolus pyruvate can transiently induce hypoxia in tumors. We investigated the mechanism underlying the induction of transient hypoxia and the combination use of pyruvate to potentiate the anti-tumor effect of TH-302., Methodology/results: The hypoxia-dependent cytotoxicity of TH-302 was evaluated by a viability assay in murine SCCVII and human HT29 cells. Modulation in cellular oxygen consumption and in vivo tumor oxygenation by the pyruvate treatment was monitored by extracellular flux analysis and electron paramagnetic resonance (EPR) oxygen imaging, respectively. The enhancement of the anti-tumor effect of TH-302 by pyruvate treatment was evaluated by monitoring the growth suppression of the tumor xenografts inoculated subcutaneously in mice. TH-302 preferentially inhibited the growth of both SCCVII and HT29 cells under hypoxic conditions (0.1% O2), with minimal effect under aerobic conditions (21% O2). Basal oxygen consumption rates increased after the pyruvate treatment in SCCVII cells in a concentration-dependent manner, suggesting that pyruvate enhances the mitochondrial respiration to consume excess cellular oxygen. In vivo EPR oxygen imaging showed that the intravenous administration of pyruvate globally induced the transient hypoxia 30 min after the injection in SCCVII and HT29 tumors at the size of 500-1500 mm(3). Pretreatment of SCCVII tumor bearing mice with pyruvate 30 min prior to TH-302 administration, initiated with small tumors (∼ 550 mm(3)), significantly delayed tumor growth., Conclusions/significance: Our in vitro and in vivo studies showed that pyruvate induces transient hypoxia by enhancing mitochondrial oxygen consumption in tumor cells. TH-302 therapy can be potentiated by pyruvate pretreatment if started at the appropriate tumor size and oxygen concentration.

Aims: The tumor microenvironment is characterized by a highly reducing redox status, a low pH, and hypoxia. Anti-angiogenic therapies for solid tumors frequently function in two steps: the transient normalization of structurally and functionally aberrant tumor blood vessels with increased blood perfusion, followed by the pruning of tumor blood vessels and the resultant cessation of nutrients and oxygen delivery required for tumor growth. Conventional anatomic or vascular imaging is impractical or insufficient to distinguish between the two steps of tumor response to anti-angiogenic therapies. Here, we investigated whether the noninvasive imaging of the tumor redox state and energy metabolism could be used to characterize anti-angiogenic drug-induced transient vascular normalization., Results: Daily treatment of squamous cell carcinoma (SCCVII) tumor-bearing mice with the multi-tyrosine kinase inhibitor sunitinib resulted in a rapid decrease in tumor microvessel density and the suppression of tumor growth. Tumor pO2 imaging by electron paramagnetic resonance imaging showed a transient increase in tumor oxygenation after 2-4 days of sunitinib treatment, implying improved tumor perfusion. During this window of vascular normalization, magnetic resonance imaging of the redox status using an exogenously administered nitroxide probe and hyperpolarized (13)C MRI of the metabolic flux of pyruvate/lactate couple revealed an oxidative shift in tumor redox status., Innovation: Redox-sensitive metabolic couples can serve as noninvasive surrogate markers to identify the vascular normalization window in tumors with imaging techniques., Conclusion: A multimodal imaging approach to characterize physiological, metabolic, and redox changes in tumors is useful to distinguish between the different stages of anti-angiogenic treatment.

Time-domain electron paramagnetic resonance imaging is currently a useful preclinical molecular imaging modality in experimental animals such as mice and is capable of quantitatively mapping hypoxia in tumor implants. The microseconds range relaxation times (T1 and T2) of paramagnetic tracers and the large bandwidths (tens of MHz) to be excited by electron paramagnetic resonance pulses for spatial encoding makes imaging of large objects a challenging task. The possibility of using multiple array coils to permit studies on large sized object is the purpose of the present work. Toward this end, the use of planar array coils in different configurations to image larger objects than cannot be fully covered by a single resonator element is explored. Multiple circular surface coils, which are arranged in a plane or at suitable angles mimicking a volume resonator, are used in imaging a phantom and a tumor-bearing mouse leg. The image was formed by combining the images collected from the individual coils with suitable scaling. The results support such a possibility. By multiplexing or interleaving the measurements from each element of such array resonators, one can scale up the size of the subject and at the same time reduce the radiofrequency power requirements and increase the sensitivity., (Copyright © 2013 Wiley Periodicals, Inc.)

Purpose: Electron paramagnetic resonance imaging has emerged as a promising noninvasive technology to dynamically image tissue oxygenation. Owing to its extremely short spin-spin relaxation times, electron paramagnetic resonance imaging benefits from a single-point imaging scheme where the entire free induction decay signal is captured using pure phase encoding. However, direct T2 (*)/pO2 quantification is inhibited owing to constant magnitude gradients which result in time-decreasing field of view. Therefore, conventional acquisition techniques require repeated imaging experiments with differing gradient amplitudes (typically 3), which results in long acquisition time., Methods: In this study, gridding was evaluated as a method to reconstruct images with equal field of view to enable direct T2 (*)/pO2 quantification within a single imaging experiment. Additionally, an enhanced reconstruction technique that shares high spatial k-space regions throughout different phase-encoding time delays was investigated (k-space extrapolation)., Results: The combined application of gridding and k-space extrapolation enables pixelwise quantification of T2 (*) from a single acquisition with improved image quality across a wide range of phase-encoding time delays. The calculated T2 (*)/pO2 does not vary across this time range., Conclusions: By utilizing gridding and k-space extrapolation, accurate T2 (*)/pO2 quantification can be achieved within a single data set to allow enhanced temporal resolution (by a factor of 3)., (Copyright © 2013 Wiley Periodicals, Inc.)

Narrow-line spin probes derived from the trityl radical have led to the development of fast in vivo time-domain EPR imaging. Pure phase-encoding imaging modalities based on the single-point imaging scheme have demonstrated the feasibility of three-dimensional oximetric images with functional information in minutes. In this article, we explore techniques to improve the temporal resolution and circumvent the relatively short biological half-lives of trityl probes using partial k-space strategies. There are two main approaches: one involves the use of the Hermitian character of the k-space by which only part of the k-space is measured and the unmeasured part is generated using the Hermitian symmetry. This approach is limited in success by the accuracy of numerical estimate of the phase roll in the k-space that corrupts the Hermiticy. The other approach is to measure only a judicially chosen reduced region of k-space (a centrosymmetric ellipsoid region) that more or less accounts for >70% of the k-space energy. Both of these aspects were explored in Fourier transform-EPR imaging with a doubling of scan speed demonstrated by considering ellipsoid geometry of the k-space. Partial k-space strategies help improve the temporal resolution in studying fast dynamics of functional aspects in vivo with infused spin probes., (Copyright © 2012 Wiley Periodicals, Inc.)

The hypoxic nature of tumors results in treatment resistance and poor prognosis. To spare limited oxygen for more crucial pathways, hypoxic cancerous cells suppress mitochondrial oxidative phosphorylation and promote glycolysis for energy production. Thereby, inhibition of glycolysis has the potential to overcome treatment resistance of hypoxic tumors. Here, EPR imaging was used to evaluate oxygen dependent efficacy on hypoxia-sensitive drug. The small molecule 3-bromopyruvate blocks glycolysis pathway by inhibiting hypoxia inducible enzymes and enhanced cytotoxicity of 3-bromopyruvate under hypoxic conditions has been reported in vitro. However, the efficacy of 3-bromopyruvate was substantially attenuated in hypoxic tumor regions (pO2<10 mmHg) in vivo using squamous cell carcinoma (SCCVII)-bearing mouse model. Metabolic MRI studies using hyperpolarized 13C-labeled pyruvate showed that monocarboxylate transporter-1 is the major transporter for pyruvate and the analog 3-bromopyruvate in SCCVII tumor. The discrepant results between in vitro and in vivo data were attributed to biphasic oxygen dependent expression of monocarboxylate transporter-1 in vivo. Expression of monocarboxylate transporter-1 was enhanced in moderately hypoxic (8-15 mmHg) tumor regions but down regulated in severely hypoxic (<5 mmHg) tumor regions. These results emphasize the importance of noninvasive imaging biomarkers to confirm the action of hypoxia-activated drugs., (Copyright © 2012 Wiley Periodicals, Inc.)

A novel time-domain spectroscopic EPR imaging approach, that is a unique combination of already known techniques, is described. The first one is multi-gradient Single Point Imaging involving pure phase-encoding where the oximetry is based on T(2)(∗). Line width derived from T(2)(∗) is subject to susceptibility effects and therefore needs system-dependent line width calibrations. The second approach utilizes the conventional 90°-τ-180° Spin-Echo pulse sequence where the images are obtained by the filtered back-projection after FT of the echoes collected under frequency-encoding gradients. The spatially resolved oximetry information is derived from a set of T(2)-weighted images. The back-projection images suffer susceptibility artifacts with resolution determined by T(2)(∗), but the oximetry based on T(2) is quite reliable. The current approach combines Single Point Imaging and the Spin-Echo procedure to take advantage the enhanced spatial resolution associated with the former and the T(2) dependent contrast of the latter. Pairs of images are derived choosing two time points located at identical time intervals on either side of the 180° pulse. The refocusing pulse being exactly in the middle of the two points ensures that artifacts associated with susceptibility and field inhomogeneities are eliminated. In addition, the net phase accumulated by the two time points being identical results in identical field of views, thus avoiding the zoom-in effect as a function delay in regular SPI and the associated interpolation requirements employed in T(2)(∗)-weighted oximetry. The end result is superior image resolution and reliable oximetry. In spite of the fact that projection-reconstruction methods require less number of measurements compared to SPI, the enormous advantage in SNR of the SPI procedure makes the echo-based SPI equally efficient in terms of measurement time. The Fourier reconstruction, line width independent resolution and the true T(2)-weighting make this novel procedure very attractive for in vivo EPR imaging of tissue oxygen quantitatively., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Electron paramagnetic resonance imaging (EPRI) can be used to noninvasively and quantitatively obtain three-dimensional maps of tumor pO₂. The paramagnetic tracer triarylmethyl (TAM), a substituted trityl radical moiety, is not toxic to animals and provides narrow isotropic spectra, which is ideal for in vivo EPR imaging experiments. From the oxygen-induced spectral broadening of TAM, pO₂ maps can be derived using EPRI. The instrumentation consists of an EPRI spectrometer and 7T magnetic resonance imaging (MRI) system both operating at a common radiofrequency of 300 MHz. Anatomic images obtained by MRI can be overlaid with pO₂ maps obtained from EPRI. With imaging times of less than 3 min, it was possible to monitor the dynamics of oxygen changes in tumor and distinguish chronically hypoxic regions from acutely hypoxic regions. In this article, the principles of pO₂ imaging with EPR and some relevant examples of tumor imaging are reviewed.

MRI using hyperpolarized (13) C-labeled pyruvate is a promising tool to biochemically profile tumors and monitor their response to therapy. This technique requires injection of pyruvate into tumor-bearing animals. Pyruvate is an endogenous entity but the influence of exogenously injected bolus doses of pyruvate on tumor microenvironment is not well understood. In this study, the effect of injecting a bolus of pyruvate on tumor oxygen status was investigated. EPR oxygen imaging revealed that the partial pressure of oxygen (pO(2)) in squamous cell carcinoma implanted in mice decreased significantly 30 min after [1-(13) C]pyruvate injection, but recovered to preinjection levels after 5 h. Dynamic contrast-enhanced-MRI studies showed that, at the dose of pyruvate used, no changes in tumor perfusion were noticed. Immunohistochemical analysis of hypoxic marker pimonidazole independently verified that the squamous cell carcinoma tumor transiently became more hypoxic by pyruvate injection. Efficacy of radiotherapy was suppressed when X-irradiation was delivered during the period of pyruvate-induced transient hypoxia. These results suggest importance of taking into account the transient decrease in tumor pO(2) after pyruvate injection in hyperpolarized (13) C MRI, because tumor oxygen status is an important factor in determining outcomes of therapies., (Copyright © 2011 Wiley Periodicals, Inc.)

Rapamycin is an allosteric inhibitor of mammalian target of rapamycin, and inhibits tumor growth and angiogenesis. Recent studies suggested a possibility that rapamycin renormalizes aberrant tumor vasculature and improves tumor oxygenation. The longitudinal effects of rapamycin on angiogenesis and tumor oxygenation were evaluated in murine squamous cell carcinoma (SCCVII) by electron paramagnetic resonance imaging (EPRI) and magnetic resonance imaging (MRI) to identify an optimal time after rapamycin treatment for enhanced tumor radioresponse. Rapamycin treatment was initiated on SCCVII solid tumors 8 days after implantation (500-750 mm(3)) and measurements of tumor pO(2) and blood volume were conducted from day 8 to 14 by EPRI/MRI. Microvessel density was evaluated over the same time period by immunohistochemical analysis. Tumor blood volume as measured by MRI significantly decreased 2 days after rapamycin treatment. Tumor pO(2) levels modestly but significantly increased 2 days after rapamycin treatment; whereas, it decreased in non-treated control tumors. Furthermore, the fraction of hypoxic area (pixels with pO(2)<10 mm Hg) in the tumor region decreased 2 days after rapamycin treatments. Immunohistochemical analysis of tumor microvessel density and pericyte coverage revealed that microvessel density decreased 2 days after rapamycin treatment, but pericyte coverage did not change, similar to what was seen with anti-angiogenic agents such as sunitinib which cause vascular renormalization. Collectively, EPRI/MRI co-imaging can provide non-invasive evidence of rapamycin-induced vascular renormalization and resultant transient increase in tumor oxygenation. Improved oxygenation by rapamycin treatment provides a temporal window for anti-cancer therapies to realize enhanced response to radiotherapy.

Oxygen maps derived from electron paramagnetic resonance spectral-spatial imaging (EPRI) are based upon the relaxivity of molecular oxygen with paramagnetic spin probes. This technique can be combined with MRI to facilitate mapping of pO(2) values in specific anatomic locations with high precision. The co-registration procedure, which matches the physical and digital dimensions of EPR and MR images, may present the pO(2) map at the higher MRI resolution, exaggerating the spatial resolution of oxygen, making it difficult to precisely distinguish hypoxic regions from normoxic regions. The latter distinction is critical in monitoring the treatment of cancer by radiation and chemotherapy, since it is well-established that hypoxic regions are three or four times more resistant to treatment compared to normoxic regions. The aim of this article is to describe pO(2) maps based on the intrinsic resolution of EPRI. A spectral parameter that affects the intrinsic spatial resolution of EPRI is the full width at half maximum (FWHM) height of the gradient-free EPR absorption line in frequency-encoded imaging. In single point imaging too, the transverse relaxation times (T(2)(∗)) limit the resolution since the signal decays by exp(-t(p)/T(2)(∗)) where the delay time after excitation pulse, t(p), is related to the resolution. Although the spin densities of two point objects may be resolved at this separation, it is inadequate to evaluate quantitative changes of pO(2) levels since the linewidths are proportionately affected by pO(2). A spatial separation of at least twice this resolution is necessary to correctly identify a change in pO(2) level. In addition, the pO(2) values are blurred by uncertainties arising from spectral dimensions. Blurring due to noise and low resolution modulates the pO(2) levels at the boundaries of hypoxic and normoxic regions resulting in higher apparent pO(2) levels in hypoxic regions. Therefore, specification of intrinsic resolution and pO(2) uncertainties are necessary to interpret digitally processed pO(2) illustrations., (Published by Elsevier Inc.)

Structural and functional abnormalities in tumor blood vessels impact the delivery of oxygen and nutrients to solid tumors, resulting in chronic and cycling hypoxia. Although chronically hypoxic regions exhibit treatment resistance, more recently it has been shown that cycling hypoxic regions acquire prosurvival pathways. Angiogenesis inhibitors have been shown to transiently normalize the tumor vasculatures and enhance tumor response to treatments. However, the effect of antiangiogenic therapy on cycling tumor hypoxia remains unknown. Using electron paramagnetic resonance imaging and MRI in tumor-bearing mice, we have examined the vascular renormalization process by longitudinally mapping tumor partial pressure of oxygen (pO(2)) and microvessel density during treatments with a multi-tyrosine kinase inhibitor sunitinib. Transient improvement in tumor oxygenation was visualized by electron paramagnetic resonance imaging 2 to 4 days following antiangiogenic treatments, accompanied by a 45% decrease in microvessel density. Radiation treatment during this time period of improved oxygenation by antiangiogenic therapy resulted in a synergistic delay in tumor growth. In addition, dynamic oxygen imaging obtained every 3 minutes was conducted to distinguish tumor regions with chronic and cycling hypoxia. Sunitinib treatment suppressed the extent of temporal fluctuations in tumor pO(2) during the vascular normalization window, resulting in the decrease of cycling tumor hypoxia. Overall, the findings suggest that longitudinal and noninvasive monitoring of tumor pO(2) makes it possible to identify a window of vascular renormalization to maximize the effects of combination therapy with antiangiogenic drugs.

A study was conveyed to produce estolide ester using ricinoleic acid as the backbone. The ricinoleic acid reacted with saturated fatty acid from C8-C18. These reactions were conducted under vacuum at 60°C for 24 h without solvent. The reaction used acid catalyst, sulphuric acid. The new saturate ricinoleic estolide esters show superior low-temperature properties (-52 ± 0.08°C) and high flash point (>300°C). The yield of the neat estolide esters ranged from 52% to 96%. The viscosity range was 51 ± 0.08 to 86 ± 0.01 cp. These new saturated estolide esters were also compared with saturated branched estolide esters.

Electron paramagnetic resonance (EPR) oximetry at 700 MHz operating frequency employing a surface coil resonator is used to assess tissue partial pressure of oxygen (pO(2)) using paramagnetic media whose linewidth and decay constant are related to oxygen concentration. Differences in extracellular and intracellular pO(2) in squamous cell carcinoma (SCC) tumor tissue were tested using several types of water-soluble paramagnetic media, which localize extracellularly or permeate through the cell membrane. The nitroxide carboxy-PROXYL (CxP) can only be distributed in blood plasma and extracellular fluids whereas the nitroxides carbamoyl-PROXYL (CmP) and TEMPOL (TPL) can permeate cell membranes and localize intracellularly. EPR signal decay constant and the linewidth of the intravenously administered nitroxides in SCC tumor tissues implanted in mouse thigh and the contralateral normal muscle of healthy mice breathing gases with different pO(2) were compared. The pO(2) in the blood can depend on the oxygen content in the breathing gas while tissue pO(2) was not directly influenced by pO(2) in the breathing gas. The decay constants of CmP and TPL in tumor tissue were significantly larger than in the normal muscles, and lower linewidths of CmP and TPL in tumor tissue was observed. The SCC tumor showed intracellular hypoxia even though the extracellular pO(2) is similar to normal tissue in the peripheral region.

Tumors exhibit fluctuations in blood flow that influence oxygen concentrations and therapeutic resistance. To assist therapeutic planning and improve prognosis, noninvasive dynamic imaging of spatial and temporal variations in oxygen partial pressure (pO(2)) would be useful. Here, we illustrate the use of pulsed electron paramagnetic resonance imaging (EPRI) as a novel imaging method to directly monitor fluctuations in oxygen concentrations in mouse models. A common resonator platform for both EPRI and magnetic resonance imaging (MRI) provided pO(2) maps with anatomic guidance and microvessel density. Oxygen images acquired every 3 minutes for a total of 30 minutes in two different tumor types revealed that fluctuation patterns in pO(2) are dependent on tumor size and tumor type. The magnitude of fluctuations in pO(2) in SCCVII tumors ranged between 2- to 18-fold, whereas the fluctuations in HT29 xenografts were of lower magnitude. Alternating breathing cycles with air or carbogen (95% O(2) plus 5% CO(2)) distinguished higher and lower sensitivity regions, which responded to carbogen, corresponding to cycling hypoxia and chronic hypoxia, respectively. Immunohistochemical analysis suggests that the fluctuation in pO(2) correlated with pericyte density rather than vascular density in the tumor. This EPRI technique, combined with MRI, may offer a powerful clinical tool to noninvasively detect variable oxygenation in tumors., ((c)2010 AACR.)

Architectural and functional abnormalities of blood vessels are a common feature in tumors. A consequence of increased vascular permeability and concomitant aberrant blood flow is poor delivery of oxygen and drugs, which is associated with treatment resistance. In the present study, we describe a strategy to simultaneously visualize tissue oxygen concentration and microvascular permeability by using a hyperpolarized (1)H-MRI, known as Overhauser enhanced MRI (OMRI), and an oxygen-sensitive contrast agent OX63. Substantial MRI signal enhancement was induced by dynamic nuclear polarization (DNP). The DNP achieved up to a 7,000% increase in MRI signal at an OX63 concentration of 1.5 mM compared with that under thermal equilibrium state. The extent of hyperpolarization is influenced mainly by the local concentration of OX63 and inversely by the tissue oxygen level. By collecting dynamic OMRI images at different hyperpolarization levels, local oxygen concentration and microvascular permeability of OX63 can be simultaneously determined. Application of this modality to murine tumors revealed that tumor regions with high vascular permeability were spatio-temporally coincident with hypoxia. Quantitative analysis of image data from individual animals showed an inverse correlation between tumor vascular leakage and median oxygen concentration. Immunohistochemical analyses of tumor tissues obtained from the same animals after OMRI experiments demonstrated that lack of integrity in tumor blood vessels was associated with increased tumor microvascular permeability. This dual imaging technique may be useful for the longitudinal assessment of changes in tumor vascular function and oxygenation in response to chemotherapy, radiotherapy, or antiangiogenic treatment.

Background: The number of patients seen at the RIPAS Hospital Anticoagulation Clinic (ACC) has increased cumulatively over the years. With patient numbers increasing dramatically, a study of the anticoagulant service has become necessary to determine the clinic's performance., Objectives: The aim of this study was to gather descriptive data on the ACC and to determine the percentage of patients' international normalised ratio (INR) results within target, below target and above target at the ACC., Methods: A cross-sectional study was conducted for all patients attending the ACC in 2005 and 2006. Patient data were collected from their warfarin chart. The results were compared between the 2 years., Results: The numbers of patients were 364 and 390 in 2005 and 2006, respectively. The male-to-female ratio was 0.95 in 2005 and 1.14 in 2006. There was no significant change in ethnic distribution between the 2 years. Most of the patients seen at the ACC were Malays, followed by Chinese and other ethnicities consisting of Caucasian, Burmese, Bisaya, Gurkha, Iban and Filipino. There was a shift in the age of population in 2006 (mean = 60.2 +/- 14.0) compared to 2005 (mean = 58.1 +/- 14.1). Of the patients, 34.6% had multiple indications requiring anticoagulation in 2005 and 29.5% in 2006. The most common indications for patients were atrial fibrillation (63% in 2005 and 61% in 2006), prosthetic valve replacement (22% in 2005 and 18% in 2006) and thrombosis (4% in 2005 and 2006). These three indications accounted for 90% of patients seen. In 2005, 33.4% of INR were below target, 49.3% within target and 17.3% above target. In 2006, 36% were below target, 51.1% were within target and 12.9% were above target., Conclusion: This was the first time such a study was conducted for the ACC. It helped us gauge our current performance, understand our practice and enable us to implement any necessary changes to improve the clinic.

Nitroxides, unlike trityl radicals, have shorter T(2)s which until now were not detectable in vivo by a time-domain pulsed Electron Paramagnetic Resonance (EPR) spectrometer at 300 MHz since their phase memory times were shorter than the spectrometer recovery times. In the current version of the time-domain EPR spectrometer with improved spectrometer recovery times, the feasibility of detecting signals from nitroxide radicals was tested. Among the nitroxides evaluated, deuterated (15)N-Tempone ((15)N-PDT) was found to have the longest T(2). The signal intensity profile as a function of concentration of these agents was evaluated and a biphasic behavior was observed; beyond a nitroxide concentration of 1.5mM, signal intensity was found to decrease as a result of self-broadening. Imaging experiments were carried out with (15)N-PDT in solutions equilibrated with 0%, 5%, 10%, and 21% oxygen using the single point imaging (SPI) modality in EPR. The image intensity in these tubes was found to depend on the oxygen concentration which in turn influences the T(2) of (15)N-PDT. In vivo experiments were demonstrated with (15)N-PDT in anesthetized mice where the distribution and metabolism of (15)N-PDT could be monitored. This study, for the first time shows the capability to image a cell-permeable nitroxide in mice using pulsed EPR in the SPI modality.

Three-dimensional Oximetric Electron Paramagnetic Resonance Imaging using the Single Point Imaging modality generates unpaired spin density and oxygen images that can readily distinguish between normal and tumor tissues in small animals. It is also possible with fast imaging to track the changes in tissue oxygenation in response to the oxygen content in the breathing air. However, this involves dealing with gigabytes of data for each 3D oximetric imaging experiment involving digital band pass filtering and background noise subtraction, followed by 3D Fourier reconstruction. This process is rather slow in a conventional uniprocessor system. This paper presents a parallelization framework using OpenMP runtime support and parallel MATLAB to execute such computationally intensive programs. The Intel compiler is used to develop a parallel C++ code based on OpenMP. The code is executed on four Dual-Core AMD Opteron shared memory processors, to reduce the computational burden of the filtration task significantly. The results show that the parallel code for filtration has achieved a speed up factor of 46.66 as against the equivalent serial MATLAB code. In addition, a parallel MATLAB code has been developed to perform 3D Fourier reconstruction. Speedup factors of 4.57 and 4.25 have been achieved during the reconstruction process and oximetry computation, for a data set with 23 x 23 x 23 gradient steps. The execution time has been computed for both the serial and parallel implementations using different dimensions of the data and presented for comparison. The reported system has been designed to be easily accessible even from low-cost personal computers through local internet (NIHnet). The experimental results demonstrate that the parallel computing provides a source of high computational power to obtain biophysical parameters from 3D EPR oximetric imaging, almost in real-time.

A priori knowledge of spatial and temporal changes in partial pressure of oxygen (oxygenation; pO(2)) in solid tumors, a key prognostic factor in cancer treatment outcome, could greatly improve treatment planning in radiotherapy and chemotherapy. Pulsed electron paramagnetic resonance imaging (EPRI) provides quantitative 3D maps of tissue pO(2) in living objects. In this study, we implemented an EPRI set-up that could acquire pO(2) maps in almost real time for 2D and in minutes for 3D. We also designed a combined EPRI and MRI system that enabled generation of pO(2) maps with anatomic guidance. Using EPRI and an air/carbogen (95% O(2) plus 5% CO(2)) breathing cycle, we visualized perfusion-limited hypoxia in murine tumors. The relationship between tumor blood perfusion and pO(2) status was examined, and it was found that significant hypoxia existed even in regions that exhibited blood flow. In addition, high levels of lactate were identified even in normoxic tumor regions, suggesting the predominance of aerobic glycolysis in murine tumors. This report presents a rapid, noninvasive method to obtain quantitative maps of pO(2) in tumors, reported with anatomy, with precision. In addition, this method may also be useful for studying the relationship between pO(2) status and tumor-specific phenotypes such as aerobic glycolysis.