A combined chemometric and quantitative NMR analysis of HIV/AIDS serum discloses metabolic alterations associated with disease status

Individuals infected with the human immunodeficiency virus (HIV) often suffer from concomitant metabolic complications. Treatment with antiretroviral therapy has also been shown to alter the metabolism of patients. Although chemometric analysis of nuclear magnetic resonance (NMR) spectra of human sera can distinguish normal sera (HIVneg) from HIV-infected sera (HIVpos) and sera from HIV-infected patients on antiretroviral therapy (ART), quantitative analysis of the discriminating metabolites and their relationship to disease status has yet to be determined. The objectives of the study were to analyze NMR spectra of HIVneg, HIVpos, and ART serum samples with a combination of chemometric and quantitative methods and to compare the NMR data with disease status as measured by viral load and CD4 count. High-resolution magic angle spinning (HRMAS) NMR spectroscopy was performed on HIVneg (N = 10), HIVpos (N = 10), and ART (N = 10) serum samples. Chemometric linear discriminant analysis classified the three groups of spectra with 100% accuracy. Concentrations of 12 metabolites were determined with a semi-parametric metabolite quantification method named high-resolution quantum estimation (HR-QUEST). CD4 count was directly associated with alanine (p = 0.008), and inversely correlated with both glutamine (p = 0.017) and glucose (p = 0.022) concentrations. A multivariate linear model using alanine, glutamine and glucose as covariates demonstrated an association with CD4 count (p = 0.038). The combined chemometric and quantitative analysis of the data disclosed previously unknown associations between specific metabolites and disease status. The observed associations with CD4 count are consistent with metabolic disorders that are commonly seen in HIV-infected patients.http://www.rsc.org/molecularbiosystemsam201

Volumetric registration framework for multimodal functional magnetic resonance and optoacoustic tomography of the rodent brain

Optoacoustic tomography (OAT) provides a non-invasive means to characterize cerebral hemodynamics across an entire murine brain while attaining multi-parametric readouts not available with other modalities. This unique capability can massively impact our understanding of brain function. However, OAT largely lacks the soft tissue contrast required for unambiguous identification of brain regions. Hence, its accurate registration to a reference brain atlas is paramount for attaining meaningful functional readings. Herein, we capitalized on the simultaneously acquired bi-modal data from the recently-developed hybrid magnetic resonance optoacoustic tomography (MROT) scanner in order to devise an image coregistration paradigm that facilitates brain parcellation and anatomical referencing. We evaluated the performance of the proposed methodology by coregistering OAT data acquired with a standalone system using different registration methods. The enhanced performance is further demonstrated for functional OAT data analysis and characterization of stimulus-evoked brain responses. The suggested approach enables better consolidation of the research findings thus facilitating wider acceptance of OAT as a powerful neuroimaging tool to study brain functions and diseases

Volumetric registration framework for multimodal functional magnetic resonance and optoacoustic tomography of the rodent brain

Optoacoustic tomography (OAT) provides a non-invasive means to characterize cerebral hemodynamics across an entire murine brain while attaining multi-parametric readouts not available with other modalities. This unique capability can massively impact our understanding of brain function. However, OAT largely lacks the soft tissue contrast required for unambiguous identification of brain regions. Hence, its accurate registration to a reference brain atlas is paramount for attaining meaningful functional readings. Herein, we capitalized on the simultaneously acquired bi-modal data from the recently-developed hybrid magnetic resonance optoacoustic tomography (MROT) scanner in order to devise an image coregistration paradigm that facilitates brain parcellation and anatomical referencing. We evaluated the performance of the proposed methodology by coregistering OAT data acquired with a standalone system using different registration methods. The enhanced performance is further demonstrated for functional OAT data analysis and characterization of stimulus-evoked brain responses. The suggested approach enables better consolidation of the research findings thus facilitating wider acceptance of OAT as a powerful neuroimaging tool to study brain functions and diseases.ISSN:2213-597

¹³C Dynamic Nuclear Polarization using SA-BDPA at 6.7 T and 1.1 K:Coexistence of Pure Thermal Mixing and Well-Resolved Solid Effect

SA-BDPA is a water-soluble, narrow-line width radical previously used for dynamic nuclear polarization (DNP) signal enhancement in solid-state magic angle spinning NMR spectroscopy. Here, we report the first study using SA-BDPA under dissolution DNP conditions (6.7 T and 1.15 K). Longitudinal-detected (LOD)-electron spin resonance (ESR) and C-13 DNP measurements were performed on samples containing 8.4 M [C-13]urea dissolved in 50:50 water:glycerol (v/v) doped with either 60 or 120 mM SA-BDPA. Two distinct DNP mechanisms, both "pure" thermal mixing and a well-resolved solid effect could clearly be identified. The radical's ESR line width (30-40 MHz), broadened predominantly by dipolar coupling, excluded any contribution from the cross effect. Microwave frequency modulation increased the enhancement by DNP at the lower radical concentration but not at the higher radical concentration. These results are compared to data acquired with trityl radical AH111501, highlighting the unusual C-13 DNP properties of SA-BDPA

Investigating tumor perfusion and metabolism using multiple hyperpolarized 13C compounds: HP001, pyruvate and urea

Introduction: Most people who stop smoking gain weight. Dietary modification may seem an obvious solution, but food restriction may increase cigarette craving and smoking relapse. Trial Design: An unblinded parallel randomised controlled trial. Methods: Participants were adult smokers with a body mass index greater or equal to 23 kg/m2. Setting was National Health Service commissioned Stop Smoking Services, interventions were referral to a commercial weight management programme, plus stop smoking support (treatment group), compared with stop smoking support alone (control group). Objective was to compare weight change between interventions in smoking abstainers and not abstinent rates in all. Primary outcome was change in weight (kg) at 12 weeks. Randomisation sequence was computer generated and concealed until allocation. Results: Seventy-six participants were recruited, 37 were randomised to the treatment group and 39 to the control group. Change in weight was analysed in long-term abstainers (13 treatment, 14 control) only because the aim was to prevent weight gain associated with smoking cessation. Abstinence was analysed on an intention-to-treat basis (37 treatment, 39 control). At 12 weeks weight gain was less in the treatment than the control group with an adjusted mean difference of −2.3 kg 95% CI (−4.4 to -0.1). Craving scores were lower (Mood and Physical Symptoms Scale craving domain −1.6 (–2.7 to –0.5)) and quit rates were higher in the treatment than the control group (32% vs 21%), although the trial was not powered to superiority in cravings and quit rates. No adverse events or side effects were reported. Conclusion: In people who are obese and want to quit smoking, these data provide modest encouragement that providing weight management at the time of quitting may be helpful. Those who are not obese, but who are informed about potential weight gain during their quit attempt, were uninterested in a weight management programme. Trial registration number: ISRCTN6570551

Use of hyperpolarized [1-13C]pyruvate and [2-13C]pyruvate to probe the effects of the anticancer agent dichloroacetate on mitochondrial metabolism in vivo in the normal rat

Development of hyperpolarized technology utilizing dynamic nuclear polarization has enabled the measurement of (13)C metabolism in vivo at very high SNR. In vivo mitochondrial metabolism can, in principle, be monitored with pyruvate, which is catalyzed to acetyl-CoA via pyruvate dehydrogenase (PDH). The purpose of this work was to determine if the compound sodium dichloroacetate (DCA) could aid the study of mitochondrial metabolism with hyperpolarized pyruvate. DCA stimulates PDH by inhibiting its inhibitor, pyruvate dehydrogenase kinase. In this work, hyperpolarized [1-(13)C]pyruvate and [2-(13)C]pyruvate were used to probe mitochondrial metabolism in normal rats. Increased conversion to bicarbonate (+181% ± 69%, p = 0.025) was measured when [1-(13C)]pyruvate was injected after DCA administration, and increased glutamate (+74% ± 23%, p = 0.004), acetoacetate (+504% ± 281%, p = 0.009), and acetylcarnitine (+377% ± 157%, p = 0.003) were detected when [2-(13)C]pyruvate was used

Application of a novel 13C hyperpolarized metabolic tracer for gamma-Glutamyl transferase activity in vivo tumor xenograft

γ-Glutamyl transferase (GGT) is membrane-bound enzyme that catalyzes the cleavage of γ-glutamyl moiety of extracellular glutathione to supply cysteine for intracellular synthesis of glutathione as anti-oxidant. Elevated GGT activity has been found in wide range of cancers, where GGT promotes tumor cell survival, tumor progression, and resistance to radiotherapy and chemotherapies. Based on biological and clinical studies, we hypothesize that non-invasive methods for real-time monitoring of GGT activity will provide the information of cancer characterization, prognosis, and development of therapeutic strategy.Hyperpolarized (HP) 13C Magnetic Resonance spectroscopy (MRS) and imaging which have been newly developed modality enable non-invasive molecular imaging of real-time metabolism in tumor. Despite of the advantageous feature, only a limited number of 13C-labeled probes have been utilized for in vivo applications because of their physicochemical property. Dr. Nishihara et al., however, have successfully designed and prepared a novel HP molecular probe for GGT activity, γ-Glu-[1-13C]Gly. γ-Glu-[1-13C]Gly was designed to produce a distinct 13C signal in chemical shift range by the enzymatic cleavage, due to the positively charged amino group of released [1-13C]Gly in physiological pH. It was demonstrated that this probe can monitor real-time GGT activity in vivo rat kidney as well as in vitro homogenate samples.Herein, we investigated to apply this novel probe with HP-MRS technology to in vivo tumor xenograft

Investigating tumor perfusion and metabolism using multiple hyperpolarized 13C compounds: HP001, pyruvate and urea

The metabolically inactive hyperpolarized agents HP001 and urea enable a new type of perfusion MRI based on a direct signal source that is background-free. The addition of perfusion information to metabolic information obtained by spectroscopic imaging of hyperpolarized [1-(13)C]pyruvate would be of great value in exploring the relationship between perfusion and metabolism in cancer. In preclinical normal murine and cancer model studies, we performed both dynamic multi-slice imaging of the specialized hyperpolarized perfusion compound HP001 (bis-1,1-(hydroxymethyl)-[1-(13)C]cyclopropane-d(8), T(1)= 95 s ex vivo, 32 s in vivo at 3T) using a pulse sequence with balanced steady state free precession (bSSFP) and ramped flip angle over time for efficient utilization of the hyperpolarized magnetization, and 3D echo planar spectroscopic imaging (EPSI) of urea co-polarized with [1-(13)C]pyruvate, with compressed sensing for resolution enhancement. For the dynamic data, peak signal maps and blood flow maps derived from perfusion modeling were generated. The spatial heterogeneity of perfusion was increased 2.9-fold in tumor tissues (p= 0.05), and slower washout was observed in the dynamic data. The results of separate dynamic HP001 imaging and co-polarized pyruvate / urea imaging were compared. A strong and significant correlation (R= 0.73, p= 0.02) detected between the urea and HP001 data confirmed the value of co-polarizing urea with pyruvate for simultaneous assessment of perfusion and metabolism