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MRI is an increasingly important clinical tool, but it is clear that conventional imaging fails to identify the full extent of lesion load in certain conditions, such as multiple sclerosis. The aim of this study was to determine whether a novel contrast agent (Gd-DTPA-B(sLeX)A, which contains an sLeX mimetic moiety that enables it to bind to the adhesion molecule E-selectin) can be used to identify endothelial activation in the brain. Microinjection of the proinflammatory cytokines IL-1beta or TNF-alpha into the striatum of Wistar rats rapidly induces focal adhesion molecule expression on the endothelium in the absence of MRI-visible changes. This phenomenon was used to investigate the potential of Gd-DTPA-B(sLeX)A to reveal MRI-invisible brain pathology. T1-weighted serial images were acquired in anesthetized animals before and after administration of Gd-DTPA-B(sLeX)A, 3-4 hr after cytokine was injected intracerebrally. Both TNF-alpha and IL-1beta up-regulated E-selectin on the brain endothelium, which correlated with increased signal intensity observed after administration of the novel contrast agent. No enhancement was visible with the nonselective contrast agent Gd-DTPA-BMA, indicating that there was no leakage of the agent across the blood-brain barrier (BBB) or nonselective binding to the endothelium. These data demonstrate the potential of such contrast agents for the early detection of brain injury and inflammation.

Multiple sclerosis is a major cause of non-traumatic neurological disability. The identification of markers that differentiate disease progression is critical to effective therapy. A combination of NMR spectroscopic metabolic profiling of urine and statistical pattern recognition was used to detect focal inflammatory central nervous system (CNS) lesions induced by microinjection of a replication-deficient recombinant adenovirus expressing TNF-alpha or IL1-beta cDNA into the brains of Wistar rats. These animals were compared with a group of naïve rats and a group of animals injected with an equivalent null adenovirus. Urine samples were collected 7 days after adenovirus injection, when the inflammatory lesion is maximally active. Principal components analysis and Partial Least Squares-Discriminate analysis of the urine (1)H NMR spectra revealed significant differences between each of the cytokine adenovirus groups and the control groups; for the TNF-alpha group the main differences lay in citrate and succinate, while for the IL-1beta group the predominant changes occurred in leucine, isoleucine, valine and myo-inositol. Thus, we can identify urinary metabolic vectors that not only separate rats with inflammatory lesions in the brain from control animals, but also distinguish between different types of CNS inflammatory lesions. Fil: Griffin, Julian L.. University of Cambridge; Reino Unido Fil: Anthony, Daniel C.. University of Southampton; Reino Unido Fil: Campbell, Sandra J.. University of Southampton; Reino Unido Fil: Gauldie, Jack. McMaster University; Canadá Fil: Pitossi, Fernando Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Styles, Peter. McMaster University; Canadá Fil: Sibson, Nicola R.. University of Oxford; Reino Unido

Prion diseases are fatal chronic neurodegenerative diseases. Previous qualitative magnetic resonance imaging (MRI) and spectroscopy (MRS) studies report conflicting results in the symptomatic stages of the disease, but little work has been carried out during the earlier stages of the disease. Here we have used the murine ME7 model of prion disease to quantitatively investigate MRI and MRS changes during the period prior to the onset of overt clinical signs (20+ weeks) and have correlated these with pathological and behavioural abnormalities. Using in vivo MRI, at the later stages of the preclinical period (18 weeks) the diffusion of tissue water was significantly reduced, coinciding with significant microglial activation and behavioural hyperactivity. Using in vivo MRS, we found early (12 weeks) decreases in the ratio of N-acetyl aspartate to both choline (NAA/Cho) and creatine (NAA/Cr) in the thalamus and hippocampus, which were associated with early behavioural deficits. Ex vivo MRS of brain extracts confirmed and extended these findings, showing early (8-12 weeks) decreases in both the neuronal metabolites NAA and glutamate, and the metabolic metabolites lactate and glucose. Increases in the glial metabolite myo-inositol were observed at later stages when microglial and astrocyte activation is substantial. These changes in MRI and MRS signals, which precede overt clinical signs of disease, could provide insights into the pathogenesis of this disease and may enable early detection of pathology.

Magnetic resonance imaging (MRI) is an established clinical tool for diagnosing multiple sclerosis (MS), the archetypal central nervous system neuroinflammatory disease. In this study, we have used a model of delayed-type hypersensitivity in the rat brain, which bears many of the hallmarks of an MS lesion, to investigate the development of MRI-detectable changes before the appearance of conventional indices of lesion development. In addition, we have correlated the MRI-detectable changes with the developing histopathology. Significant increases in regional cerebral blood volume (rCBV) preceded overt changes in blood–brain barrier (BBB) permeability, T2 relaxation and the diffusion properties of tissue water. Thus, changes in rCBV might be a more sensitive indicator of lesion onset than the conventional indices used clinically in MS patients, such as contrast enhancement. In addition, we show that BBB breakdown, and consequent edema formation, are more closely correlated with astrogliosis than any other histopathologic changes, while regions of T1 and T2 hypointensity appear to reflect hypercellularity.

Cardiomyopathy is a frequent cause of morbidity and mortality in patients carrying the A3243G transition in the mitochondrial DNA (mtDNA) tRNALeu(UUR) gene, the most common heteroplasmic single mtDNA defect. We used phosphorus magnetic resonance spectroscopy (31P-MRS) to look for evidence of an in vivo bioenergetics defect in patients carrying the A3243G mtDNA mutation with and without echocardiographic signs of left ventricle hypertrophy (LVH). Eight patients, three with LVH, carrying the A3243G mtDNA mutation and 10 healthy subjects underwent one-dimensional chemical shift imaging 31P-MRS. In the patients, mean cardiac phosphocreatine to adenosine triphosphate ratio (PCr/ATP) (1.55±0.58) was significantly reduced compared to the control group (2.34±0.14; P

Magnetic resonance techniques were used to investigate haemodynamic abnormalities and their consequences in normal pressure hydrocephalus (NPH) and to assess changes in these parameters following surgery. Eleven patients with NPH were studied pre- and post-operatively using perfusion and diffusion weighted imaging and compared with ten age-matched controls. Pre-operative periventricular relative cerebral blood volume (rCBV) was reduced in patients (0.76+/-0.11) compared with control (1.16+/-0.16, P0.01). There was no difference between outcome groups and no change in haemodynamic parameters following surgery. The periventricular apparent diffusion coefficient (ADC) was elevated in the poor outcome group (1.67+/-0.3 x 10(-3) mm(2) s(-1)) compared with both controls (1.04+/-0.4 x 10(-3) mm(2) s(-1), P0.05) and the good outcome group (0.99+/-0.3 x 10(-3) mm(2) s(-1), P0.05) despite appearing normal on conventional imaging. In white matter hyperintensities (WMH), rCBV was reduced (0.70+/-0.12 vs. 1.00+/-0.10, P0.01), and the ADC was increased (1.98+/-0.6 vs. 1.04+/-0.4 x 10(-3) mm(2) s(-1), P0.05) compared with the same anatomical location in controls. As low rCBV and high ADC is characteristic of chronic infarction, the findings in WMH regions suggest they are irreversibly damaged. Normal appearing periventricular tissue rCBV was reduced, implying that significant haemodynamic consequences contribute to symptoms in NPH. The elevated pre-operative ADC of the same region, was correlated with poor outcome, and may, therefore, be useful in selecting patients for surgery.

The causes of dyslexia are unknown, but previous studies have suggested an immunological basis in some cases. We hypothesised that maternal antibodies, which cross the placenta and bind to fetal antigens, could be responsible, particularly when the dyslexia recurs in consecutive pregnancies. We injected serum samples from five mothers of two or more children with dyslexia into pregnant mice, and tested the offspring for behavioural abnormalities and cerebellar metabolites by magnetic resonance spectroscopy (MRS). Mice exposed in utero to serum factors from one woman with two dyslexic children, who had also had three spontaneous fetal losses, showed deficits in motor tests which correlated with cerebellar choline (Cho) and creatine (Cr) levels. These preliminary results are consistent with a role for maternal serum factors, probably antibodies, in causing some of the features of dyslexia, and possibly in other neurodevelopmental disorders.

Major advances have been made in the ever-expanding field of magnetic resonance imaging and related technologies, such as magnetic resonance spectroscopy, haemodynamic and functional imaging. Although these magnetic resonance modalities are of great research interest, it is still questionable as to how useful these investigations are in the clinical setting. All of these modalities strive to define a few variables that might dominate the heterogeneous but common aetiopathology of traumatic brain injury. Recent studies have found that the use of various magnetic resonance imaging techniques at early and delayed time points can provide useful information with regard to the severity and clinical outcome of patients following traumatic brain injury. These new observations offer opportunities for improved clinical management in such patients.

Friedreich's ataxia (FA) is the most common form of autosomal recessive spinocerebellar ataxia and is often associated with a cardiomyopathy. The disease is caused by an expanded intronic GAA repeat, which results in deficiency of a mitochondrial protein called frataxin. In the yeast YFH1 knockout model of the disease there is evidence that frataxin deficiency leads to a severe defect of mitochondrial respiration, intramitochondrial iron accumulation, and associated production of oxygen free radicals. Recently, the analysis of FA cardiac and skeletal muscle samples and in vivo phosphorus magnetic resonance spectroscopy (31P-MRS) has confirmed the deficits of respiratory chain complexes in these tissues. The role of oxidative stress in FA is further supported by the accumulation of iron and decreased aconitase activities in cardiac muscle. We used 31P-MRS to evaluate the effect of 6 months of antioxidant treatment (Coenzyme Q10 400 mg/day, vitamin E 2,100 IU/day) on cardiac and calf muscle energy metabolism in 10 FA patients. After only 3 months of treatment, the cardiac phosphocreatine to ATP ratio showed a mean relative increase to 178% (p = 0.03) and the maximum rate of skeletal muscle mitochondrial ATP production increased to 139% (p = 0.01) of their respective baseline values in the FA patients. These improvements, greater in prehypertrophic hearts and in the muscle of patients with longer GAA repeats, were sustained after 6 months of therapy. The neurological and echocardiographic evaluations did not show any consistent benefits of the therapy after 6 months. This study demonstrates partial reversal of a surrogate biochemical marker in FA with antioxidant therapy and supports the evaluation of such therapy as a disease-modifying strategy in this neurodegenerative disorder.

Huntington's disease (HD) is an autosomal dominant condition involving progressive neurodegeneration, primarily the corpus striatum and cerebral cortex. We have used in vivo magnetic resonance spectroscopy (MRS) to assess specific neuronal markers in transgenic mice (R6/1 line) expressing exon I of the human huntingtin gene with an expanded CAG repeat. Levels of N-acetylaspartate (NAA), an indicator of healthy neuronal function, were significantly reduced (26%) in the corpus striatum of HD mice relative to wild-type littermates at 5 months of age. However, levels of cholines and creatine-phosphocreatine were not altered in the HD mice. Expression of dopamine- and cAMP-regulated phosphoprotein, 32 kDa (DARPP-32), was assessed by immunohistochemistry in the striatum of HD mice and found to be downregulated by 5 months and, even more dramatically, at 11 months of age. In contrast, expression of calbindin was not significantly decreased in HD mice. Our results suggest that the observed decreases in DARPP-32 and NAA may contribute to aberrant receptor signalling and neuronal dysfunction in HD.

The long-term clinical outcome following traumatic brain injury (TBI) can be difficult to predict. Proton magnetic resonance spectroscopy (MRS) has previously been used to demonstrate abnormalities in regions of white matter that appear normal on conventional imaging in patients following TBI. We report MRI and MRS studies of 26 patients performed at an early time point following injury (mean 12 days, n = 21) and at a later time point (mean 6.2 months, n = 15). The proton MRS was acquired from the posterior part of a normal-appearing frontal lobe containing predominantly white matter using stimulated echo acquisition mode to localize, with a relaxation time of 3000 ms and echo time of 30 ms. At both the early and late time points the N:-acetylaspartate/creatine ratio (NAA/Cr) was significantly reduced (P = 0.03, P = 0.005, respectively), the choline/creatine ratio (Cho/Cr) significantly increased (P = 0.001, P = 0.004, respectively) and the myo-inositol/creatine ratio (Ins/Cr) significantly increased (P = 0.03, P = 0.03, respectively) compared with controls. There was a small, but significant, further reduction (P = 0.02) in the NAA/Cr between the two studies in the 10 patients for whom data was available, at both time points. The NAA/Cr acquired at the early time point significantly correlated with the clinical outcome of the patients, assessed using either the Glasgow outcome scale (P = 0.005, n = 17) or the disability rating scale (P < 0.001, n = 17). We conclude that there is a sustained alteration in NAA and Cho. These findings provide possible evidence for cellular injury (NAA loss reflecting neuroaxonal cell damage and raised Cho and Ins reflecting glial proliferation) not visible by conventional imaging techniques. This may be relevant to understanding the extent of disability following TBI.

We studied in vivo muscle energy metabolism in patients with Huntington's disease (HD) and dentatorubropallidoluysian atrophy (DRPLA) using 31P magnetic resonance spectroscopy (MRS). Twelve gene-positive HP patients (4 presymptomatic patients) and 2 gene-positive DRPLA patients (1 presymptomatic patient) were studied. 31P-MRS at rest showed a reduced phosphocreatine-to-inorganic phosphate ratio in the symptomatic HD patients and DRPLA patient. Muscle adenosine triphosphate/(phosphocreatine + inorganic phosphate) at rest was significantly reduced in both groups of symptomatic and presymptomatic HD subjects and was below the normal range in the 2 DRPLA subjects. During recovery from exercise, the maximum rate of mitochondrial adenosine triphosphate production was reduced by 44% in symptomatic HD patients and by 35% in presymptomatic HD carriers. The maximum rate of mitochondrial adenosine triphosphate production in muscle was also reduced by around 46% in the 2 DRPLA subjects. Our findings show that HD and DRPLA share a deficit of in vivo mitochondrial oxidative metabolism, supporting a role for mitochondrial dysfunction as a factor involved in the pathogenesis of these polyglutamine repeat-mediated neurodegenerative disorders. The identification of 31P-MRS abnormalities may offer a surrogate biochemical marker by which to study disease progression and the effects of treatment in HD and DRPLA.

Neuropsychological studies in patients who have suffered traumatic brain injury show that the eventual clinical outcome is frequently worse than might be predicted from using conventional (CT or T(1)/T(2)-weighted MRI) imaging. Furthermore, patients who have sustained an initial mild or moderate injury may show long-term disability. This implies that there may be abnormalities in areas of the brain that actually appear normal on conventional imaging. Proton magnetic resonance spectroscopy studies have shown that N-acetylaspartate and choline-containing compounds can provide measures of cellular injury. We report MRI and proton magnetic resonance spectroscopy studies of 19 head-injured patients performed once the patients were clinically stable (mean 11 days after injury, range 3-38 days). Proton magnetic resonance spectra were acquired from frontal white matter that on conventional MRI appeared normal. The brain N-acetylaspartate/creatine ratio was reduced [patients (mean +/- standard deviation), 1.28 +/- 0.25; controls, 1.47 +/- 0. 24; P = 0.04] and the choline/creatine ratio was increased (patients, 0.85 +/- 0.18; controls, 0.63 +/- 0.10; P0.001) compared with controls. When the severity of the injury was assessed using either the Glasgow coma scale or the length of post-traumatic amnesia, the increase in the choline/creatine ratio was significant even in the mildly injured group (P = 0.008 and P = 0.04, respectively). Furthermore, there was a significant correlation (P = 0.008) between the severity of head injury and the N-acetylaspartate/choline ratio. We conclude that there is an early reduction in N-acetylaspartate and an increase in choline compounds in normal-appearing white matter which correlate with head injury severity, and that this may provide a pathological basis for the long-term neurological disability that is seen in these patients.

The primary pathological mechanisms in stroke and multiple sclerosis (MS) are very different but in both diseases, impairment may arise from a final common pathway of axonal damage. We aimed to examine the relationship between motor impairment, magnetisation transfer ratio (MTR) (an index of demyelination), and N-acetyl aspartate (NAA) loss (an index of axonal injury) localised to the descending motor pathways in stroke and MS. Twelve patients between 1 and 10 months after first ischaemic stroke causing a motor deficit and 12 patients with stable MS with asymmetric motor deficit were examined. T(2)-weighted imaging of the brain together with MTR and proton (voxel 1.5x2x2 cm(3)) MRS localised to the posterior limb of the internal capsule were performed and correlated to a composite motor deficit score. MTR and NAA in the internal capsule were reduced in both stroke and MS patients compared to controls. NAA loss correlated with motor deficit score in both stroke and MS (p

We studied mitochondrial function in vivo in 2 brothers harboring the mitochondrial DNA A3243G mutation by using magnetic resonance spectroscopy. One brother presented with recurrent strokes and had a mitochondrial respiratory chain complex I defect, with 85% A3243G mutation in his quadriceps. The maximum rate of mitochondrial ATP production in his calf, measured in vivo, was reduced to 21% of the normal mean value. The second brother had mild exercise intolerance, normal muscle histochemistry, and normal respiratory chain activity in vitro. Despite a level of the A3243G mutation of only 5.95% (SD, 4.45; range, 0.7-16.1%) within single muscle fibers from the gastrocnemius muscle, the maximum rate of mitochondrial ATP production in his calf, measured in vivo, was reduced to 35% of the normal mean value. These findings suggest that there may not be a clear genetic threshold level for the expression of the A3243G mutation in skeletal muscle in vivo.

The aim of this MR study was to determine if vasospasm induced by application of endothelin-1 (ET-1) in the rat brain would model the abnormalities attributed to vasospasm described in patients with subarachnoid haemorrhage (SAH) with reversible neurological deficits. Following application of ET-1 in concentrations of 10(-4) M or 10(-6) M to the middle cerebral artery, there was an immediate drop in pH, an increase in the inorganic phosphate (P(i)) to phosphocreatine (PCr) ratio and elevated lactate. There was gradual recovery to control in the 10(-6) M group, but in the 10(-4) M group there was a loss of approximately 10% in the absolute signal intensities of PCr and adenosine triphosphate (ATP). In a second similarly treated group of animals, the area of the hemisphere with a low apparent diffusion coefficient (ADC) was 27 +/- 6% at 30 min and remained at about 20-21% at 90 min and beyond. Together these data suggest that the regions with persistently low ADC were metabolically compromised, with incomplete recovery of PCr and ATP, and represent irreversibly damaged tissue. This raises the possibility that MR spectroscopy and imaging could be a sensitive indicator of tissue viability. This is a potentially useful model of low flow as seen in clinical vasospasm following SAH.

Purpose: MR imaging of post mortem brains has the potential to yield volumetric information and define the extent of structural changes prior to pathological examination. Although standard T2-weighted clinical imaging sequences have been used for the examination of formalin-fixed brains, these protocols may not yield optimum contrast. We examined the effect of varying durations of formalin fixation on the transverse relaxation time (T2) and the tissue spin density. Material and Methods: Three post mortem brains were examined weekly during formalin fixation from the unfixed state to 35 days fixation. Standard MR spin-echo imaging was used at 5 echo times (20–100 ms) to calculate transverse relaxation time (T2) and spin density. Results: T2 decreased significantly (ANOVA, p Conclusion: Our results suggest that spin density-weighted imaging sequences would provide improved grey to white matter contrast over T2-weighted sequences.

Summary Becker muscular dystrophy is an X-linked disorder due to mutations in the dystrophin gene, resulting in reduced size and/or content of dystrophin. The functional role of this subsarcolemmal protein and the biochemical mechanisms leading to muscle necrosis in Becker muscular dystrophy are still unknown. In particular, the role of a bioenergetic deficit is still controversial. In this study, we used 31 P magnetic resonance spectroscopy ( 31 PMRS) to investigate skeletal muscle mitochondrial and glycolytic ATP production in vivo in 14 Becker muscular dystrophy patients. Skeletal muscle glycogenolytic ATP production, measured during the first minute of exercise, was similar in patients and controls. On the other hand

Duchenne muscular dystrophy (DMD) is a progressive muscle disorder associated with an intellectual deficit which is non-progressive. We obtained localised 1H magnetic resonance spectra from the left frontal lobe and left cerebellum of 15 boys with DMD (mean age 106 months+/-32) and 15 similarly aged control boys (mean age 115 months+/-31); all boys underwent a battery of neuropsychological tests. We found a significant (P0.01) increase in the ratio of choline-containing compounds to N-acetylaspartate (Cho/NA) in the left cerebellum in boys with DMD compared with control boys. There was no change in the creatine/NA ratio and a significant increase (P=0.03) in the Cho/creatine ratio, suggesting that the change in Cho/NA ratio was due to an increase in choline-containing compounds; this increase has been previously observed in the brain of the murine model of DMD, the mdx mouse. No significant changes were observed in spectra obtained from left frontal lobe in DMD compared to controls. We also observed a significant association between Cho/NA in the left cerebellum, and the performance of DMD boys on the Matrix Analogies Test (MAT). The MAT is a test of visuo-spatial ability and non-verbal reasoning which requires neither manual dexterity nor a verbal response for an adequate performance. A comparison of DMD boys whose cerebellar Cho/NA fell within 2 standard deviations of the control norm (0.56+/-0.24) with DMD boys whose cerebellar Cho/NA was outside this range (i.e.0.80) revealed a significant difference in ability on the MAT (P0.05). DMD boys whose Cho/NA ratio is more than two standard deviations higher than controls perform significantly better on the MAT than DMD boys whose Cho/NA ratio is within the normal range. This finding suggests that the observed elevation in Cho/NA and Cho/creatine is not associated with intellectual deficit (as sampled by the MAT), and may represent a compensatory mechanism. The possible interpretations of these metabolic changes are discussed.

Summary Background Neurological and physiological deficits have been reported in the brain in developmental dyslexia. The temporoparietal cortex has been directly implicated in dyslexic dysfunction, and substantial indirect evidence suggests that the cerebellum is also implicated. We wanted to find out whether the neurological and physiological deficits manifested as biochemical changes in the brain. Methods We obtained localised proton magnetic resonance spectra bilaterally from the temporo-parietal cortex and cerebellum of 14 well-defined dyslexic men and 15 control men of similar age. Findings We found biochemical differences between dyslexic men and controls in the left temporo-parietal lobe (ratio of choline-containing compounds [Cho] to N-acetylaspartate [NA] p≤0·01) and right cerebellum (Cho/NA, p≤0·01; creatine [Cre] to NA p≤0·05; (not significant). We found lateral biochemical differences in dyslexic men in both these brain regions (Cho/NA in temporo-parietal lobe, left vs right, p≤0·01; Cre/NA in cerebellum, left vs right, p≤0·001). We found no such lateral differences in controls. There was no significant relation between the degree of contralateral chemical difference and handedness in dyslexic or control men. Interpretation We suggest that the observed differences reflect changes in cell density in the temporo-parietal lobe in developmental dyslexia and that the altered cerebral structural symmetry in dyslexia is associated with abnormal development of cells or intracellular connections or both. The cerebellum is biochemically asymmetric in dyslexic men, indicating altered development of this organ. These differences provide direct evidence of the involvement of the cerebellum in dyslexic dysfunction.

We combined magnetic resonance (MR) imaging and phosphorus magnetic resonance spectroscopy ( 31 P-MRS) to study skeletal muscle in seven patients with limb girdle muscular dystrophy (LGMD) with a variable deficiency of the α -, β -, and γ -sarcoglycan but normal dystrophin expression on muscle biopsy. T1- and T2-weighted spin-echo axial leg images showed the highest degree of fat replacement in soleus, tibialis anterior and peroneal muscles while gastrocnemius and tibialis posterior were less affected. In LGMD patients as a group, calf muscle phosphorylated compound content did not differ from controls, but the cytosolic pH was increased ( P =0.02). The degree of calf muscle fat replacement correlated inversely with cytosolic pH ( r =0.74) and directly with PCr/ATP ( r =0.74). Muscle oxidative metabolism was normal in LGMD patients. Our findings show that primary deficits of sarcoglycan complex lead to specific morphological and metabolic patterns of skeletal muscle involvement.

We show how quantitative information about proton handling in human skeletal muscle in exercise and recovery can be obtained by 31P MRS and illustrate this with data from metabolic disorders. Proton production, proton efflux and passive buffering can be distinguished by comparing changes in [phosphocreatine] and pH at the end of exercise and by calculating ATP turnover during ischaemic exercise and in the 'natural experiment' of myophosphorylase deficiency (McArdle's disease). We calculate the effective buffer capacity to be 20-30 mmol/L/pH unit (slykes), somewhat lower than published measurements made in vitro but similar to other values obtained in vivo. This analysis is applied to data from normal muscle and a variety of disease states to estimate proton efflux during recovery and ATP production during exercise: (i) proton efflux during recovery is pH-dependent, reaching a 10 mmol/L/min at pH 6.2, and is increased in some cases of mitochondrial myopathy and in hypertension; (ii) glycogenolytic ATP production during exercise can reach 25 mmol/L/min in normal muscle and correlates approximately with [Pi] at the start of aerobic exercise and throughout ischaemic exercise; (iii) oxidative ATP production can reach 20-25 mmol/L/min and (as during recovery) correlates approximately with [Pi].

Background and Purpose— Previous 31 P–magnetic resonance spectroscopy ( 31 P-MRS) studies have shown that cerebral cortical energy metabolism is abnormal in migraine and that cortical energy reserves decrease with increasing severity and duration of aura. Migrainous infarction is a rare complication of migraine with aura, and its pathophysiology is poorly understood. We used 31 P-MRS to determine whether migrainous stroke shows similar interictal abnormalities in cortical energy metabolism as severe, prolonged aura. Methods— We used 31 P-MRS to study patients with a diagnosis of either migrainous infarction or migraine with persistent aura without infarction (aura duration >7 days) according to International Headache Society criteria. We compared clinical presentation and metabolite ratios between patient groups. We also studied healthy controls with no history of migraine. Results— Patients with persistent aura without infarction had lower phosphocreatine-phosphate (PCr/Pi) ratios (mean±SD, 1.61±0.10) compared with controls (1.94±0.35, P =0.011) and with patients with migrainous stroke (1.96±0.16, P Conclusions— The differences in cortical energy reserves between patients with migrainous stroke and in those with migraine with persistent aura suggest that the pathomechanisms of these conditions differ and that migrainous infarction does not simply represent a particularly severe form of migrainous aura. This finding supports the revised International Headache Society criteria, which now distinguish between migrainous infarction and migraine with persistent aura without infarction.

The new non-invasive method of 31P nuclear magnetic resonance (NMR) has been applied for the first time to human muscle. The metabolic response to exercise--a fall in intracellular pH, a fall in phosphocreatine content, and an increase in inorganic phosphate (Pi) content--occurs without any change in ATP content of the exercised muscle. Abnormal spectra occur in two myopathies examined to date: in McArdle's syndrome, pH rises during exercise, in contrast to the normal fall; and, in an unusual mitochondrial myopathy, Pi content is high, relative to phosphocreatine content, and in keeping with an excessive oxygen consumption in this patient. Intracellular pH reflected, in addition, the systemic pH of the subject; the anticipated abnormalities in muscle pH have been observed in association with lactic acidosis, renal failure and hyperventilation.

Previous studies suggest an abnormal cerebral cortical energy metabolism in migraineurs. If causally related to the pathophysiology of migraine, these abnormalities might show a dose-response relationship with the duration and severity of aura symptoms. While such a trend has been suggested in phosphorus spectroscopy (31P-MRS) studies, it has not been considered in proton spectroscopy (1H-MRS) studies and it has not been studied in cerebral white matter. We aimed to determine whether for any of the metabolites measured by 31P-MRS or 1H-MRS there was a dose-response relationship with aura duration and severity, and whether such an association was also present in cerebral white matter. We studied patients with migraine with aura and healthy controls with 31P-MRS and with 1H-MRS. We measured metabolite ratios in grey and in white matter and in the patients, we related metabolite levels to the clinical characteristics and duration of the aura. In patients, the phosphocreatine/phosphate (PCr/Pi) ratio decreased significantly with increasing aura duration and was significantly lower in patients with hemiplegic migraine than in patients with non-motor aura. Overall the metabolite ratios did not differ significantly between patients and controls, but compared with controls the PCr/Pi ratio in patients with hemiplegic migraine and in patients with persistent aura >7 days was significantly lower. These changes were only present in grey matter. Results for 1H-MRS did not differ significantly between patients and controls, and they showed no association with duration or severity of symptoms. In this study, metabolite ratios differed significantly between patients with different aura phenotypes and with increasing aura duration. In addition, only in some patient subgroups were metabolite ratios significantly different from controls. These findings support the concept that migraine with aura is a heterogeneous disorder with distinct pathophysiological subtypes. They further suggest that rather than determining the susceptibility to developing a migraine attack, changes in cortical energy metabolism may determine the clinical manifestations of the migrainous aura once an attack has started.

BACKGROUND: The Marfan syndrome is an inherited multisystem disorder caused by mutations in fibrillin 1, with cardiovascular involvement being the most important feature of the phenoptype. Affected individuals have impaired flow-mediated dilatation (FMD) of large arteries of a similar severity to patients with chronic heart failure (CHF). AIMS: Skeletal muscle bioenergetics were studied in patients with the Marfan syndrome in order to evaluate the impact of impaired flow-mediated dilatation on skeletal muscle metabolism. Skeletal muscle metabolism is abnormal in CHF and the aetiology is unclear. METHODS: Thirteen patients and 12 controls were studied by phosphorus Magnetic Resonance spectroscopy of the calf muscle using an incremental exercise protocol and by Magnetic Resonance imaging. RESULTS: Metabolic variables measured at rest were normal in Marfan patients. For a similar total work output measured at end of the standardized incremental exercise, the total rate of energy consumption (EC) was significantly increased in patients (21.2 +/- 2.3 mM ATP/min/W vs 13.6 +/- 1.4 mM ATP/min/W in controls). Similarly, both PCr and pH time-dependent changes were significantly different between groups. The absolute contributions of aerobic and glycolytic pathways to energy production were significantly higher in patients whereas they were similar when expressed relative to EC. CONCLUSIONS: The higher EC measured in patients with Marfan syndrome was supported by both oxidative and anaerobic metabolic pathways, thereby suggesting a decrease in muscle efficiency and/or muscle mass, as previously described in other diseases affecting skeletal muscle function such as heart failure and peripheral vascular disease.

Sandhoff disease, one of several related lysosomal storage disorders, results from the build up of N-acetyl-containing glycosphingolipids in the brain and is caused by mutations in the genes encoding the hexosaminidase beta-subunit. Affected individuals undergo progressive neurodegeneration in response to the glycosphingolipid storage. (1)H magnetic resonance spectra of perchloric acid extracts of Sandhoff mouse brain exhibited several resonances ca 2.07 ppm that were not present in the corresponding spectra from extracts of wild-type mouse brain. High-performance liquid chromatography and mass spectrometry of the Sandhoff extracts post-MRS identified the presence of N-acetylhexosamine-containing oligosaccharides, which are the likely cause of the additional MRS resonances. MRS of intact brain tissue with magic angle spinning also showed additional resonances at ca 2.07 ppm in the Sandhoff case. These resonances appeared to increase with disease progression and probably arise, for the most part, from the stored glycosphingolipids, which are absent in the aqueous extracts. Hence in vivo MRS may be a useful tool for detecting early-stage Sandhoff disease and response to treatment.

Background: Chronic heart failure (CHF) is associated with abnormalities of skeletal muscle metabolism. This may be due to impaired oxygen delivery as a result of endothelial dysfunction. Aims: We postulated that ascorbic acid would improve oxygen delivery to exercising muscle and improve skeletal muscle metabolism. Methods: We studied skeletal muscle metabolism using 31P magnetic resonance spectroscopy in 39 CHF patients. Endothelial function was assessed by changes in pulse wave velocity. Subjects were randomised to receive 4g ascorbic acid daily for 4weeks in a placebo-controlled double-blind study. Results: Ascorbic acid significantly increased phosphocreatine utilization during exercise. In addition, glycolytic ATP synthesis increased in the ascorbic acid group (change in rate of ATP synthesis at 1min −0.21±0.76 with placebo, 2.06±0.60 following ascorbic acid; p

Background: Decreased mitochondrial respiratory chain function and increased oxidative stress have been implicated in the pathogenesis of Friedreich ataxia (FRDA), raising the possibility that energy enhancement and antioxidant therapies may be an effective treatment.Objective: To evaluate the long-term efficacy of a combined antioxidant and mitochondrial enhancement therapy on the bioenergetics and clinical course of FRDA.Design: Open-labeled pilot trial over 47 months.Patients: Seventy-seven patients with clinical and genetically defined FRDA.Intervention: A combined coenzyme Q(10) (400 mg/d) and vitamin E (2100 IU/d) therapy of 10 patients with FRDA over 47 months.Main Outcome Measures: Clinical assessment using echocardiography and the International Cooperative Ataxia Rating Scale and cardiac and skeletal muscle bioenergetics, as assessed using phosphorus P 31 magnetic resonance spectroscopy.Results: There was a significant improvement in cardiac and skeletal muscle bioenergetics that was maintained throughout the 47 months of therapy. Echocardiographic data revealed significantly increased fractional shortening at the 35- and 47-month time points. Comparison with cross-sectional data from 77 patients with FRDA indicated the changes in total International Cooperative Ataxia Rating Scale and kinetic scores over the trial period were better than predicted for 7 patients, but the posture and gait and hand dexterity scores progressed as predicted.Conclusion: This therapy resulted in sustained improvement in mitochondrial energy synthesis that was associated with a slowing of the progression of certain clinical features and a significant improvement in cardiac function.

Calcium-mediated excitotoxicity and defective energy metabolism have been implicated in the pathogenesis of Huntington disease (HD).1 In R6/2 HD transgenic mice, administration of 2% dietary creatine presymptomatically at 6 and 8 weeks improved survival, delayed motor progression, and reduced weight loss and brain atrophy.2,3 Creatine buffers intracellular energy reserves and has several neuroprotective effects demonstrated both in vivo and in vitro.4 A placebo-controlled pilot trial of 5 g/day of creatine for 1 year appeared ineffective in 26 patients with HD,5 although this dose was lower than the equivalent dose given to R6/2 HD mice. We previously reported clinical and MR spectroscopy (MRS) findings in a 1-year open-label pilot study of high-dose creatine (10 g/day) supplementation in 13 patients with HD.6 Serial 31P-MRS of muscle monitored changes in energy metabolism in vivo, and 1H-MRS was used to determine creatine levels in brain tissue. High-dose creatine was well tolerated, and total motor score (TMS), functional capacity, and neuropsychology testing remained stable at 12 months. We now report …

Following diffuse traumatic brain injury, there may be persistent functional or psychological deficits despite the presence of normal conventional MR images. Previous experimental animal and human studies have shown diffusion abnormalities following focal brain injury. Our aim was to quantify changes in apparent diffusion coefficient (ADC) and absolute relaxation times of normal appearing white matter (NAWM) in humans following traumatic brain injury. Twenty-three patients admitted with a diagnosis of head injury (nine mild, eight moderate, and six severe) were scanned an average of 7.6 days after injury using a quantitative echo planar imaging acquisition to obtain co-registered T1, T2, and ADC parametric maps. Mean NAWM values were compared with a control group (n = 13). The patient group showed a small but significant increase in ADC in NAWM, with no significant change in T1 or T2 relaxation times. There was a correlation between injury severity and increasing ADC (p = 0.03) but no correlation with either T1 or T2, suggesting that ADC is a sensitive and independent marker of diffuse white matter tissue damage following traumatic insult. None of the patients had a reduced ADC, making ischaemia unlikely in this cohort. Pathophysiological mechanisms that may explain diffusely raised ADC include vasogenic edema, chronic ischemic phenomena, or changes in tissue cytoarchitecture or neurofilament alignment.

Background— It is well known that patients with type 2 diabetes have increased risk of cardiovascular disease, but it is not known whether they have underlying abnormalities in cardiac or skeletal muscle high-energy phosphate metabolism. Methods and Results— We studied 21 patients with type 2 diabetes with no evidence of coronary artery disease or impaired cardiac function, as determined by echocardiography, and 15 age-, sex-, and body mass index-matched control subjects. Cardiac high-energy phosphate metabolites were measured at rest using 31 P nuclear magnetic resonance spectroscopy (MRS). Skeletal muscle high-energy phosphate metabolites, intracellular pH, and oxygenation were measured using 31 P MRS and near infrared spectrophotometry, respectively, before, during, and after exercise. Although their cardiac morphology, mass, and function appeared to be normal, the patients with diabetes had significantly lower phosphocreatine (PCr)/ATP ratios, at 1.50±0.11, than the healthy volunteers, at 2.30±0.12. The cardiac PCr/ATP ratios correlated negatively with the fasting plasma free fatty acid concentrations. Although skeletal muscle energetics and pH were normal at rest, PCr loss and pH decrease were significantly faster during exercise in the patients with diabetes, who had lower exercise tolerance. After exercise, PCr recovery was slower in the patients with diabetes and correlated with tissue reoxygenation times. The exercise times correlated negatively with the deoxygenation rates and the hemoglobin (Hb)A 1c levels and the reoxygenation times correlated positively with the HbA 1c levels. Conclusions— Type 2 diabetic patients with apparently normal cardiac function have impaired myocardial and skeletal muscle energy metabolism related to changes in circulating metabolic substrates.

Neurodevelopmental disorders could be caused by maternal antibodies or other serum factors. We detected serum antibodies binding to rodent Purkinje cells and other neurons in a mother of three children: the first normal, the second with autism, and the third with a severe specific language disorder. We injected the serum (0.5–1.0ml/day) into pregnant mice during gestation and found altered exploration and motor coordination and changes in cerebellar magnetic resonance spectroscopy in the mouse offspring, comparing with offspring of mice injected with sera from mothers of healthy children. This evidence supports a role for maternal antibodies in some forms of neurodevelopmental disorder. Ann Neurol 2003;53:533–537

Progression of disability in multiple sclerosis (MS) appears related to axonal damage, which is at least in part associated with white matter lesions. Beta-interferon (BIFN) substantially reduces new inflammatory activity in MS and a recent report suggested that it may reverse a component of axonal injury. To test the generalisability of this conclusion, particularly in a population with relatively active disease, we used magnetic resonance spectroscopy measures to test whether BIFN can reverse or arrest progression of axonal injury in patients with MS. Eleven patients with a history of active (median, 1.5 relapses/year) relapsing-remitting MS were treated with BIFN and responses to treatment were monitored with serial MRI and single voxel magnetic resonance spectroscopic measurements of relative concentrations of brain N-acetylaspartate (NAA), a measure of axonal integrity from a central, predominantly white matter brain region. BIFN treatment was associated with a significant reduction in relapse rate (p = 0.007) and white matter water T2 relaxation time (p = 0.047) over 12 months. Also consistent with a treatment effect, white matter T2-hyperintense lesion loads did not increase. However, the central white matter NAA/creatine ratio (NAA/Cr, which was reduced over 16 % in patients relative to healthy controls at the start of treatment), continued to decrease in the patients over the period of observation (mean 6.2 % decrease, p = 0.02). For individual patients the magnitude of the NAA/Cr decrease was correlated with the frequency of relapses over the two years prior to treatment (r = -0.76, p = 0.006). These data suggest that reduction of new inflammatory activity with BIFN does not invariably halt progression of axonal injury. Nonetheless, there appears to be a relationship between the rate of progression of axonal injury and relapse rate over the previous two years. The consequences of reduced inflammation on pathological progression relevant to disability therefore may be present, but substantially delayed. Alternatively, distinct mechanisms may contribute to the two processes.

Changes in metabolites detected by proton magnetic resonance spectroscopy ((1)H MRS) of the brain have been demonstrated in Alzheimer's disease. Our objectives were, first, longitudinally to measure absolute concentrations of metabolites in both hippocampi, the sites of early Alzheimer's disease, in patients with clinical Alzheimer's disease and controls; secondly, to separate the relative contribution of atrophy and metabolite concentration change to overall signal change; and, thirdly, to determine whether metabolite concentrations in the hippocampus relate to cognitive scores. (1)H MR spectra were acquired from a single voxel (12 x 15 x 25 mm(3) = 4.5 ml) aligned to the long axis of each hippocampus in nine probable or possible Alzheimer's disease subjects diagnosed according to the National Institute of Neurologic and Cognitive Disorders and Stroke (NINCDS) compared with 14 age-matched NINCDS-negative Alzheimer's disease controls. Metabolite concentrations were corrected for the amount of CSF present in the voxel. Hippocampal volumes were measured at the same time. The same protocol was repeated approximately 1 year later. We found that atrophy-corrected hippocampal N-acetylaspartate (NAA) concentration was lower in cognitively impaired subjects compared with controls. This was significant for the left hippocampus (baseline 87% of control, P = 0.013; and at 1 year 76% of control, P = 0.020). Hippocampal volumes also differed significantly between the groups, and decreased significantly over 1 year in the Alzheimer's disease group (12%, P = 0.017). The decrease in [NAA] over 1 year was not significant in either group. Discriminant analysis revealed that the best classification of subjects was by including both left NAA concentration and left hippocampal volume. myo-Inositol signals from these small voxels had poor signal-to-noise and demonstrated no significant changes. We conclude that (1)HMRS-detectable metabolites can be quantified from the hippocampi of cognitively impaired individuals, and that hippocampal [NAA] is significantly reduced in Alzheimer's disease, in excess of atrophy. In our cohort, the differences were more significant for the left hippocampus.

Quantitative MRI and phosphorus magnetic resonance spectroscopy ((31)P-MRS) were used to investigate skeletal muscle metabolism in vivo in patients with dermatomyositis (DM) and polymyositis (PM) in order to evaluate the role of mitochondrial abnormalities in the pathogenesis and clinical expression of these conditions. Nine patients with DM (mean age +/- SD, 57 +/- 14 years) and five with PM (42 +/- 12 years) and with age at disease onset 53 +/- 16 and 38 +/- 12 years, respectively, were included in the study together with 18 age-matched controls. Post-exercise (31)P-MRS indices of muscle oxidative metabolism were all impaired in DM and PM. In both groups of patients, the phosphocreatine and adenosine diphosphate recovery half-times were almost twice as long as in controls (P < 0.05 for each variable) and the maximum rate of mitochondrial ATP production was half that found in normal subjects (P < 0.001). The rate of proton efflux from muscle fibres was significantly reduced in DM (P < 0.001) and PM (P = 0.02). The impairment of (31)P-MRS recovery indices in DM and PM patients was similar to that found in a group of 10 patients with a primary mitochondrial disorder that showed a normal proton efflux rate. There was no correlation between the MRS-detectable abnormalities and the degree of inflammation or fatty infiltration of the muscle, as measured by MRI. The in vivo findings in DM and PM patients indicate impaired muscle aerobic function, which, considering the reduced proton efflux, is likely to be secondary to an impaired blood supply. Our results suggest that the abnormal mitochondria seen in some muscle biopsies are unlikely to be the primary cause of the oxidative insufficiency in these patients.

Friedreich's ataxia (FRDA), the most common inherited ataxia, is an autosomal recessive degenerative disorder caused by a GAA triplet expansion or point mutations in the FRDA gene on chromosome 9q13. The FRDA gene product, frataxin, is a widely expressed mitochondrial protein, which is severely reduced in FRDA patients. The demonstration that deficit of frataxin in FRDA is associated with mitochondrial iron accumulation, increased sensitivity to oxidative stress, deficit of respiratory chain complex activities and in vivo impairment of cardiac and skeletal muscle tissue energy metabolism, has established FRDA as a "new" nuclear encoded mitochondrial disease. Pilot studies have shown the potential effect of antioxidant therapy based on idebenone or coenzyme Q 10 plus Vitamin E administration in this condition and provide a strong rationale for designing larger randomized clinical trials.

Recent evidence has suggested cerebellar anomalies in developmental dyslexia. Therefore, we investigated cerebellar morphology in subjects with documented reading disabilities. We obtained T1-weighted magnetic resonance images in the coronal and sagittal planes from 11 males with prior histories of developmental dyslexia, and nine similarly-aged male controls. Proton magnetic resonance spectra (TE=136ms, TR=2.4s) were obtained bilaterally in the cerebellum. Phonological decoding skill was measured using non-word reading. Handedness was assessed using both the Annett questionnaire of hand preference and Annett's peg moving task. Cerebellar symmetry was observed in the dyslexics but there was significant asymmetry (right grey matter>left grey matter) in controls. The interpretation of these results depended whether a motor- or questionnaire-based method was used to determine handedness. The degree of cerebellar symmetry was correlated with the severity of dyslexics' phonological decoding deficit. Those with more symmetric cerebella made more errors on a nonsense word reading measure of phonological decoding ability. Left cerebellar metabolite ratios were shown to correlate significantly with the degree of cerebellar asymmetry (P

Objective: Friedreich ataxia (FRDA), the commonest form of inherited ataxia, is often associated with cardiac hypertrophy and cardiac dysfunction is the most frequent cause of death. In 97%, FRDA is caused by a homoplasmic GAA triplet expansion in the FRDA gene on chromosome 9q13 that results in deficiency of frataxin, a mitochondrial protein of unknown function. There is evidence that frataxin deficiency leads to a severe defect of mitochondrial respiration associated with abnormal mitochondrial iron accumulation. To determine whether bioenergetics deficit underlies the cardiac involvement in Friedreich ataxia (FRDA) we measured cardiac phosphocreatine to ATP ratio non-invasively in FRDA patients. Methods and results: Eighteen FRDA patients and 18 sex- and age-matched controls were studied using phosphorus MR spectroscopy and echocardiography. Left ventricular hypertrophy was present in eight FRDA patients while fractional shortening was normal in all. Cardiac PCr/ATP in FRDA patients as a group was reduced to 60% of the normal mean (P

Aim To examine daytime liver glycogen accumulation in prepubertal children with Type 1 diabetes mellitus (Type 1 DM) compared with non-diabetic controls. Methods Liver glycogen content was ascertained in the fasting (morning) and fed (afternoon) state using 13C magnetic resonance (MR) spectroscopy. Data were analysed from six children with Type 1 DM (median (range) age 8.7 (6.3–12.2) years), who were all on conventional insulin regimens, and six healthy controls (age 8.9 (7–10.2) years). Results Children with diabetes tended to have lower fasting glycogen values than controls but this did not reach statistical significance (median (range) 154 (70–177) vs. 178 (120–203) mM glycosyl units, Type 1 DM vs. controls respectively; P = 0.06). Glycogen increased in all children with diabetes during the day and concentrations were similar to those in controls by the afternoon (175 (157–299) vs. 172 (136–238) mM glycosyl units; P = 0.7). Conclusions The ability of young children with Type 1 DM to replace liver glycogen depleted after an overnight fast was at least as good as that in control subjects, suggesting that impaired glycogen storage is not a contributory factor in nocturnal hypoglycaemia. Diabet. Med. 18, 659–662 (2001)

Experimental studies have reported early reductions in pH, phosphocreatine, and free intracellular magnesium following traumatic brain injury using phosphorus magnetic resonance spectroscopy. Paradoxically, in clinical studies there is some evidence for an increase in the pH in the subacute stage following traumatic brain injury. We therefore performed phosphorus magnetic resonance spectroscopy on seven patients in the subacute stage (mean 9 days postinjury) following traumatic brain injury to assess cellular metabolism. In areas of normal-appearing white matter, the pH was significantly alkaline (patients 7.09 +/- 0.04 [mean +/- SD], controls 7.01 +/- 0.04, p = 0.008), the phosphocreatine to inorganic phosphate ratio (PCr/Pi) was significantly increased (patients 4.03 +/- 1.18, controls 2.64 +/- 0.71, p = 0.03), the inorganic phosphate to adenosine triphosphate ratio (Pi/ATP) was significantly reduced (patients 0.37 +/- 0.10, controls 0.56 +/- 0.19, p = 0.04), and the PCr/ATP ratio was nonsignificantly increased (patients 1.53 +/- 0.29, controls 1.34 +/- 0.19, p = 0.14) in patients compared to controls. Furthermore, the calculated free intracellular magnesium was significantly increased in the patients compared to the controls (patients 0.33 +/- 0.09 mM, controls 0.22 +/- 0.09 mM, p = 0.03)). Proton spectra, acquired from similar regions showed a significant reduction in N-acetylaspartate (patients 9.64 +/- 2.49 units, controls 12.84 +/- 2.35 units, p = 0.03) and a significant increase in choline compounds (patients 7.96 +/- 1.02, controls 6.67 +/- 1.01 units, p = 0.03). No lactate was visible in any patient or control spectrum. The alterations in metabolism observed in these patients could not be explained by ongoing ischemia but might be secondary to a loss of normal cellular homeostasis or a relative alteration in the cellular population, in particular an increase in the glial cell density, in these regions.

OBJECTIVES: Our aim was to measure the cardiac phosphocreatine to adenosine triphosphate ratio (PCr/ATP) noninvasively in patients and carriers of Xp21 muscular dystrophy and to correlate the results with left ventricular (LV) function as measured by echocardiography. BACKGROUND: Duchenne and Becker muscular dystrophy (the Xp21 dystrophies) are associated with the absence or altered expression of dystrophin in cardiac and skeletal muscles. They are frequently complicated by cardiac hypertrophy and dilated cardiomyopathy. The main role of dystrophin is believed to be structural, but it may also be involved in signaling processes. Defects in energy metabolism have been found in skeletal muscle in patients with Xp21 muscular dystrophy. We therefore hypothesized that a defect in energy metabolism may be part of the mechanism leading to the cardiomyopathy of Xp21 muscular dystrophy. METHODS: Thirteen men with Becker muscular dystrophy, 10 female carriers and 23 control subjects were studied using phosphorus-31 magnetic resonance spectroscopy and echocardiography. RESULTS: The PCr/ATP was significantly reduced in patients (1.55+/-0.37) and carriers (1.37+/-0.25) as compared with control subjects (2.44+/-0.33; p

Background and Purpose —Infarct size on T2-weighted MRI correlates only modestly with outcome, particularly for small strokes. This may be largely because of differences in the locations of infarcts and consequently in the functional pathways that are damaged. To test this hypothesis quantitatively, we developed a “mask” of the corticospinal pathway to determine whether the extent of stroke intersection with the pathway would be more closely related to clinical motor deficit and axonal injury in the descending motor pathways than total stroke lesion volume. Methods —Eighteen patients were studied ≥1 month after first ischemic stroke that caused a motor deficit by use of brain T2-weighted imaging, MR spectroscopic (MRS) measurements of the neuronal marker compound N -acetyl aspartate in the posterior limb of the internal capsule, and motor impairment and disability measures. A corticospinal mask based on neuroanatomic landmarks was generated from a subset of the MRI data. The maximum proportion of the cross-sectional area of this mask occupied by stroke was determined for each patient after all brain images were transformed into a common stereotaxic brain space. Results —There was a significant linear relationship between the maximum proportional cross-sectional area of the corticospinal mask occupied by stroke and motor deficit ( r 2 =0.82, P r 2 =0.76, P N -acetyl aspartate reduction. Conclusions —Segmentation of functional motor pathways on MRI allows estimation of the extent of damage specifically to that pathway by the stroke lesion. The extent of stroke intersection with the motor pathways was more linearly related to the magnitude of motor deficit than total lesion volume and appeared to be a better discriminator between small strokes with regard to motor deficit. This emphasizes the importance of the anatomic relationship of the infarct to local structures in determining functional impairment. Prospective studies are necessary to assess whether this approach would allow improved early estimation of prognosis after stroke.

ANovartisPharmaAG, Basle, Switzerland Summary Background: MKT 077 is a rhodacyanine dye analogue which preferentially accumulates in tumour cell mitochondria. It is cytotoxic to a range of tumours. In this phase I study, MKT 077 was administered as a five-day infusion once every three weeks. Patients and methods: Ten patients, median age 59 (38-70) years, with advanced solid cancers were treated at three dose levels: 30, 40 and 50 mg/m 2 /day for a total of 18 cycles. 31 Phosphorus magnetic resonance spectroscopy (MRS) was used to evaluate the effect of MKT077 on skeletal muscle mitochondrial function. Results: The predominant toxicity was recurrent reversible functional renal impairment (grade 2, two patients). One patient with renal cancer attained stable disease and the remainder progressive disease. There were no MRS changes in the first or second treatment cycles but one patient received 11 treatment cycles and developed changes consistent with a mitochondrial myopathy. Mean values for all pharmacokinetic parameters were at sub micromolar levels and did not exceed IC50 values (>1 uM). Conclusions: Because of the renal toxicity, and animal studies showing MKT 077 causes eventual irreversible renal toxicity, further recruitment was halted. The study shows, however, that it is feasible to target mitochondria with rhodacyanine analogues, if drugs with higher therapeutic indices could be developed.

Sporadic inclusion body myositis (s-IBM) is a chronic inflammatory myopathy of unknown pathogenesis. The common findings of ragged red fibres, cytochrome c oxidase-negative fibres and multiple mitochondrial DNA deletions in the muscle of patients with s-IBM have suggested that a deficit of energy metabolism may be of pathogenic relevance. To test this hypothesis we used 31P magnetic resonance spectroscopy to assess in vivo skeletal muscle mitochondrial function in the calf muscles of 12 patients with definite s-IBM. Eleven patients showed multiple mitochondrial DNA deletions in skeletal muscle and 67% showed ragged red fibres and/or cytochrome c oxidase-negative fibres. T1-weighted MR images showed increased signal intensity in the calf muscle of all patients except one. The involvement of calf muscle was confirmed by 31P magnetic resonance spectroscopy of resting muscle, which disclosed abnormalities in metabolite ratios in all patients. However, muscle oxidative metabolism assessed during recovery from exercise was normal in patients with s-IBM, as maximum rates of mitochondrial ATP production and post-exercise ADP recovery rates were within the normal range in all cases. We conclude that muscle mitochondrial abnormalities are a secondary process and unlikely to play a significant role in the pathogenesis of s-IBM.

Objective: To determine what biochemical changes may occur in the brain in Williams syndrome (WS) and whether these changes may be related to the cognitive deficits. Background: WS is a rare, congenital disorder with a characteristic physical, linguistic, and behavioral phenotype with known cognitive deficits. Methods: We obtained 31 P magnetic resonance spectra (MRS) from a region consisting of mostly frontal and parietal lobe of 14 patients with WS (age, 8 to 37 years) and 48 similarly-aged controls. 1 H MRS (27 cm 3 ) localized to the left cerebellum obtained from the WS cohort were compared with those from 16 chronological age- and sex-matched normal controls. A battery of cognitive tests were administered to all subjects undergoing 1 H MRS. Results: WS brains exhibited significant biochemical abnormalities. All 31 P MRS ratios containing the phosphomonoester (PME) peak were significantly altered in WS, suggesting that PME is significantly decreased. Ratios of choline-containing compounds and creatine-containing compounds to N-acetylaspartate (Cho/NA and Cre/NA) were significantly elevated in the cerebellum in WS cf. controls, whereas the ratio of Cho/Cre was not altered. This suggests a decrease in the neuronal marker N-acetylaspartate in the cerebellum. Significant correlations were found between the cerebellar ratios Cho/NA and Cre/NA and the ability of all subjects at various neuropsychological tests, including Verbal and Performance IQ, British Picture Vocabulary Scale, Ravens Progressive Matrices, and Inspection Time. Conclusions: The correlations can be interpreted in two ways: 1) Our sampling of cerebellar biochemistry reflects a measure of "global" cerebral biochemistry and is unrelated to cerebellar function, or 2) The relations indicate that cerebellar neuronal integrity is a requirement (on a developmental time scale or in real-time) for ability on a variety of cognitive tests.

We used 31P magnetic resonance spectroscopy (31P-MRS) to assess in vivo skeletal muscle mitochondrial function in 10 Leber's hereditary optic neuropathy patients/carriers with a mitochondrial DNA (mtDNA) mutation at one of three nucleotide positions, 11,778, 14,484, and 3,460. We studied one affected patient for each mutation and two unaffected carriers with the 11,778 or 3,460 mutation and three carriers with 14,484. All subjects were homoplasmic except the two 3,460 carriers, who showed 80% and 15% of mutated mtDNA. 31P-MRS at rest disclosed some abnormalities in all subjects. In particular, the phosphorylation potential was below the normal range in all cases. During recovery from exercise, the maximum rate of mitochondrial ATP production (Vmax) was reduced to 27% of normal in the 11,778 mutation and to 53% in the 14,484 mutation patient/carrier groups. Mitochondrial Vmax was within the normal range in all subjects with the 3,460 mutation but correlated inversely with the percentage of mutated mtDNA. This in vivo study shows that the 11,778 mutation causes a mitochondrial impairment more severe than the 14,484 and that the 3,460 mutation results in only a mild depression of muscle mitochondrial function.

Duchenne muscular dystrophy (DMD) is one of a range of muscular dystrophies caused by abnormalities of the short arm of the X chromosome (Xp21), which often cause mental retardation in addition to progressive muscular weakness. Normal dystrophin expression is lacking in both skeletal muscle and brain of affected subjects. Phosphorus-31 magnetic resonance spectroscopy has shown several abnormalities in skeletal muscle in DMD. We looked for similar abnormalities in brain in patients with DMD and related the findings to neuropsychological test results. We studied by magnetic resonance spectroscopy 19 boys (aged 76-167 months) diagnosed as having DMD and 19 control boys of similar age (87-135 months). Intelligence quotient (IQ) was assessed with the Wechsler Intelligence Scale for children. The DMD patients had significantly higher values than the controls in the brain ratios of inorganic phosphate to adenosine triphosphate (mean 0.53 [SD 0.21] vs 0.36 [0.09], p = 0.003), to phosphomonoesters (0.40 [0.07] vs 0.29 [0.07], p = 0.0001), and to phosphocreatine (0.44 [0.10] vs 0.37 [0.08], p = 0.02). There were significant differences between the DMD patients and the controls in full-scale IQ (76 [16] vs 101 [16], p = 0.0001), performance IQ (78 [17] vs 94 [14], p = 0.003), and verbal IQ (78 [17] vs 106 [17], p = 0.0001). These altered metabolite ratios parallel the findings in dystrophic muscle and suggest bioenergetic similarities in tissues that lack dystrophin.

We use the hyperbolic relationship between cytosolic [ADP] and the rate of phosphocreatine (PCr) resynthesis after exercise to estimate the apparent maximum rate of oxidative ATP synthesis (QMAX). We examine data from some human diseases in which mitochondrial oxidation may be impaired (due to reduced mitochondrial numbers, intrinsic mitochondrial defect or impaired vascular supply). Muscle responds to impaired oxidation by stimulating anaerobic ATP synthesis and/or by increasing [ADP], the stimulus to the mitochondrion. However, these responses interact: [ADP] depends on pH and [PCr], and lactic acid production tends to lower [ADP] (by lowering pH), while proton efflux has the opposite effect. We identify four patterns of results: (A) in mitochondrial myopathy, apparent QMAX is reduced and [ADP] is appropriately increased, because increased proton efflux reduces the pH change in exercise despite increased lactic acid production; (B) in some conditions (e.g., cyanotic congenital heart disease) apparent QMAX is reduced but there is no compensatory rise in [ADP], probably because anaerobic ATP synthesis during exercise is increased without increase in proton efflux; (C) in other conditions (e.g., myotonic dystrophy) [ADP] is increased during exercise but apparent QMAX is normal, suggesting either an increase in proton efflux and/or decrease in anaerobic ATP synthesis during exercise; (D) there are also conditions (e.g., respiratory failure) where, despite impaired oxygen supply, both apparent QMAX and end-exercise [ADP] are normal. We also discuss the metabolic conditions under which end-exercise [ADP] is increased by a mitochondrial defect. Finally, we discuss some technical aspects, including the effects of an altered mitochondrial Km for ADP and the relationship of the analysis to the halftime of PCr recovery and an alternative calculation of apparent QMAX.

Ischaemic brain events necessitate prompt diagnosis and clinical intervention if the ischaemia is to be reversed. At present, MR is unable to distinguish between reversibly and irreversibly damaged tissue. Although apparent diffusion coefficient (ADC) MRI is established as a sensitive indicator of acute ischaemia, an unresolved challenge is to non-invasively distinguish between reversibly and irreversibly damaged tissue early in the ischaemic event. Endothelin-1 (ET-1) produces a potent and prolonged vasoconstrictive effect on the brain vasculature and has been used as a model of low flow ischaemia in the rat brain. We hypothesise that a focal striatal injection of ET-1 creates a graduated lesion consisting of both reversibly and irreversibly damaged tissue. A longitudinal study of MR-visible changes following intrastriatal ET-1 injection in the juvenile rat brain was conducted and correlated with the metabolic status of brain tissue using phosphorus (31P) MRS. Male Wistar rats (50-55 g) were anaesthetised by inhalation using 2% isoflurane in 70% N2O:30% O2. Using a minimally-invasive stereotaxic procedure, 160pmoles of ET-1 was injected in a volume of 1.0 l of sterile saline into the striatum (n=8). Animals were positioned in a purpose-built head restraint system and a 2 cm-diameter single-turn circular surface phosphorus coil was placed over the animal's head. Anaesthesia was maintained in the magnet using 1% isoflurane in 70% N2O:30% O2. T1 and T2-weighted images, DWI and 31P spectra were obtained using a 7 T horizontal bore magnet (Magnex Scientific) interfaced to a Varian/SISCO spectrometer (Varian, Palo Alto, CA, USA). We observed a significant decrease in the ADC around the site of injection at 2.5 h post-injection [Figure 1a & e]. MRI was repeated at 6, 24 and 72 hrs over which time ADC changes resolved in the periphery of the lesion, but remained low at the core. These findings suggest that the tissue at the core of the lesion may be irreversibly damaged whereas normalisation of ADC in the periphery may be indicative of reversibly damaged tissue. 31P spectra from the whole of the injected hemisphere did not detect any reductions in the PCr to ATP ratio. Significant changes in these metabolites may only occur in the speculated irreversibly damaged core of the lesion, which constitutes less than 25% of the 31P MRS voxel. The inclusion of a significant volume of healthy tissue in the 31P MRS voxel may explain the absence of a change in metabolite levels. Ongoing studies are investigating the perfusion changes in the core and peripheral regions of ET-1-induced focal lesions and their correlation with ADC changes.