Alkaline pH in intracranial tuberculomas: A 31Phosphorus magnetic resonance spectroscopy study

Objectives

Intracranial tuberculomas are one of the common causes of space-occupying lesions of the brain in developing countries. Proton (1H) magnetic resonance spectroscopy (MRS) has shown lipid peak in intracranial tuberculomas as a characteristic feature. Phosphorus (31P) MRS has been used to evaluate intracranial lesions and to calculate tissue pH non-invasively. The aim of this study is to evaluate intracranial tuberculomas using 31PMRS.

Materials and Methods

Intracranial tuberculomas proven by stereotactic or surgical biopsy were included in the study. After routine T1- and T2-weighted sequences, 31P MRS was performed using single-voxel intravoxel in vivo spectroscopy (ISIS) technique in the central core of the tuberculoma (voxel size 1-2 mm3). The pH was estimated using Petroff 's method using the chemical shift between phosphocreatine and Pi.

Results

31P MRS was available for 26 patients, in which there was significant positive correlation between high-energy phosphate metabolites, (markers of bioenergetic status), and low-energy phosphate metabolites (membrane phospholipids and inorganic phosphate). The calculated pH was slightly alkaline and varied from 6.97 to 7.22.

Conclusion

Intracranial tuberculomas showed alkaline pH in 31P MRS and this may be useful in the characterization of these lesions and possibly also in their treatment.

Nicotinic acid receptor agonists impair myocardial contractility by energy starvation

Nicotinic acid receptor agonists have previously been shown to cause acute reductions in cardiac contractility. We sought to uncover the changes in cardiac metabolism underlying these alterations in function. In nine humans, we recorded cardiac energetics and function before and after a single oral dose of nicotinic acid using cardiac MRI to demonstrate contractile function and Phosphorus-31 (31 P) magnetic resonance spectroscopy to demonstrate myocardial energetics. Nicotinic Acid 400 mg lowered ejection fraction by 4% (64 ± 8% to 60 ± 7%, P = .03), and was accompanied by a fall in phosphocreatine/ATP ratio by 0.4 (2.2 ± 0.4 to 1.8 ± 0.1, P = .04). In four groups of eight Wistar rats, we used pyruvate dehydrogenase (PDH) flux studies to demonstrate changes in carbohydrate metabolism induced by the nicotinic acid receptor agonist, Acipimox, using hyperpolarized Carbon-13 (13 C) magnetic resonance spectroscopy. In rats which had been starved overnight, Acipimox caused a fall in ejection fraction by 7.8% (67.5 ± 8.9 to 60 ± 3.1, P = .03) and a nearly threefold rise in flux through PDH (from 0.182 ± 0.114 to 0.486 ± 0.139, P = .002), though this rise did not match pyruvate dehydrogenase flux observed in rats fed carbohydrate rich chow (0.726 ± 0.201). In fed rats, Acipimox decreased pyruvate dehydrogenase flux (to 0.512 ± 0.13, P = .04). Concentration of plasma insulin fell by two-thirds in fed rats administered Acipimox (from 1695 ± 891 ng/L to 550 ± 222 ng/L, P = .005) in spite of glucose concentrations remaining the same. In conclusion, we demonstrate that nicotinic acid receptor agonists impair cardiac contractility associated with a decline in cardiac energetics and show that the mechanism is likely a combination of reduced fatty acid availability and a failure to upregulate carbohydrate metabolism, essentially starving the heart of fuel.

Effect of a multicomponent exercise intervention on brain metabolism: A randomized controlled trial on Alzheimer's pathology (Dementia-MOVE)

BACKGROUND

Physical activity has shown a positive impact on aging and neurodegeneration and represents a possible treatment option in cognitive decline. However, its underlying mechanisms and influences on brain pathology remain unclear. Dementia-MOVE (Multi-Objective Validation of Exercise) is a randomized-controlled pilot trial, including 50 patients with amnestic cognitive impairment associated with Alzheimer's pathology, aiming to analyze the effect of physical activity and fitness on disease progression.

METHODS

Dementia-MOVE is divided into two arms, of either an intervention comprising physical activity, for at least twice a week, combined with a psychoeducational program, or a sole psychoeducational program. Physical activity intervention includes a supervised and unsupervised multimodal concept combining resistance, endurance, coordinative, and aerobic training. The primary outcome is the change of brain metabolism due to physical interventional treatment. Besides metabolic magnetic resonance imaging (MRI) including sodium and phosphorus imaging, resting state functional MRI, T1-, T2-weighted and fluid-attenuated inversion recovery (FLAIR), as well as diffusion-weighted imaging (DWI) of the brain and whole-body fat MRI are performed before and after intervention, and will be compared in their sensitivity for the detection of intervention effects. We further assess cognitive performance, neuropsychiatric symptoms, quality of life, fitness, and sleep via questionnaires/interviews and/or fitness trackers, as well as microbiome, under the aspect of Alzheimer's pathology.

DISCUSSION

The aim of Dementia-MOVE is to investigate the effect of a multimodal exercise program on Alzheimer's pathology under different aspects of the disease. In this context, one of the main aims is the comparison of different MRI methods regarding their responsiveness for the detection of alterations induced by physical activity. As an underlying goal, new treatment and diagnostic options, as well as the exploration of fitness effects on brain structure and metabolism within a whole-body perspective of Alzheimer's disease are envisaged.

Phosphorus magnetic resonance spectroscopic imaging using flyback echo planar readout trajectories

OBJECT

To present and evaluate a fast phosphorus magnetic resonance spectroscopic imaging (MRSI) sequence using echo planar spectroscopic imaging with flyback readout gradient trajectories.

MATERIALS AND METHODS

Waveforms were designed and implemented using a 3 Tesla MRI system. ³¹P spectra were acquired with 2 × 2 cm² and 3 × 3 cm² resolution over a 20- and 21-cm field of view and spectral bandwidths up to 1923 Hz. The sequence was first tested using a 20-cm-diameter phosphate phantom, and subsequent in vivo tests were performed on healthy human calf muscles and brains from five volunteers.

RESULTS

Flyback EPSI achieved 10× and 7× reductions in acquisition time, with 68.0 ± 1.2 and 69.8 ± 2.2% signal-to-noise ratio (SNR) per unit of time efficiency (theoretical SNR efficiency was 74.5 and 76.4%) for the in vivo experiments, compared to conventional phase-encoded MRSI for the 2 × 2 cm² and 3 × 3 cm² resolution waveforms, respectively. Statistical analysis showed no difference in the quantification of most metabolites. Time savings and SNR comparisons were consistent across phantom, leg and brain experiments.

CONCLUSION

EPSI using flyback readout trajectories was found to be a reliable alternative for acquiring ³¹P-MRSI data in a shorter acquisition time.

Metformin prevents ischemia reperfusion-induced oxidative stress in the fatty liver by attenuation of reactive oxygen species formation

Nonalcoholic fatty liver disease is associated with chronic oxidative stress. In our study, we explored the antioxidant effect of antidiabetic metformin on chronic [high-fat diet (HFD)-induced] and acute oxidative stress induced by short-term warm partial ischemia-reperfusion (I/R) or on a combination of both in the liver. Wistar rats were fed a standard diet (SD) or HFD for 10 wk, half of them being administered metformin (150 mg·kg body wt(-1)·day(-1)). Metformin treatment prevented acute stress-induced necroinflammatory reaction, reduced alanine aminotransferase and aspartate aminotransferase serum activity, and diminished lipoperoxidation. The effect was more pronounced in the HFD than in the SD group. The metformin-treated groups exhibited less severe mitochondrial damage (markers: cytochrome c release, citrate synthase activity, mtDNA copy number, mitochondrial respiration) and apoptosis (caspase 9 and caspase 3 activation). Metformin-treated HFD-fed rats subjected to I/R exhibited increased antioxidant enzyme activity as well as attenuated mitochondrial respiratory capacity and ATP resynthesis. The exposure to I/R significantly increased NADH- and succinate-related reactive oxygen species (ROS) mitochondrial production in vitro. The effect of I/R was significantly alleviated by previous metformin treatment. Metformin downregulated the I/R-induced expression of proinflammatory (TNF-α, TLR4, IL-1β, Ccr2) and infiltrating monocyte (Ly6c) and macrophage (CD11b) markers. Our data indicate that metformin reduces mitochondrial performance but concomitantly protects the liver from I/R-induced injury. We propose that the beneficial effect of metformin action is based on a combination of three contributory mechanisms: increased antioxidant enzyme activity, lower mitochondrial ROS production, and reduction of postischemic inflammation.

Cerebral vascular control is associated with skeletal muscle pH in chronic fatigue syndrome patients both at rest and during dynamic stimulation

Cerebral blood flow (CBF) is maintained despite changing systemic blood pressure through cerebral vascular control, with such tight regulation believed to be under local tissue control. Chronic fatigue syndrome (CFS) associates with a wide range of symptoms, including orthostatic intolerance, skeletal muscle pH abnormalities and cognitive impairment. CFS patients are known to have reduced CBF and orthostatic intolerance associates with abnormal vascular regulation, while skeletal muscle pH abnormalities associate with autonomic dysfunction. These findings point to autonomic dysfunction as the central feature of CFS, and cerebral vascular control being influenced by factors outside of the brain, a macroscopic force affecting the stability of regional regulation. We therefore explored whether there was a physiological link between cerebral vascular control and skeletal muscle pH management in CFS. Seventeen consecutive CFS patients fulfilling the Fukuda criteria were recruited from our local CFS clinical service. To probe the static scenario, CBF and skeletal muscle pH were measured at rest using MRI and (31)P magnetic resonance spectroscopy ((31)P-MRS). To examine dynamic control, brain functional MRI was performed concurrently with Valsalva manoeuvre (VM), a standard autonomic function challenge, while (31)P-MRS was performed during plantar flexion exercise. Significant inverse correlation was seen between CBF and skeletal muscle pH at rest (r = - 0.67, p < 0.01). Prolonged cerebral vascular constriction during the sympathetic phase of VM was associated with higher pH in skeletal muscle after plantar flexion exercise (r = 0.69, p < 0.008). In conclusion, cerebral vascular control is closely related to skeletal muscle pH both at rest and after dynamic stimulation in CFS.