One-dimensional image-selected in vivo spectroscopy localized phosphorus saturation transfer at 7T.

PURPOSE: To evaluate the feasibility of a one-dimensional image-selected in vivo spectroscopy (1D-ISIS) saturation transfer (ST) sequence at 7T for localized in vivo measurements of energy metabolism in different tissues in clinically reasonable examination times. METHODS: The performance of a gradient offset independent adiabacity-based 1D-ISIS localization was tested on phantom and the localized ST sequence was compared with the nonlocalized version in vivo. We performed localized measurements of basal metabolism of human liver and different muscle groups of the calf. Localized ST experiments took 15-25 minutes. RESULTS: The selectivity of the 1D-ISIS sequence was 81.63% and the outer volume suppression was 97.57%. The ST parameters acquired with the 1D-ISIS sequence and with the nonlocalized acquisition in the muscle were not statistically different. The forward rate constants for phosphocreatine (PCr)-adenosine triphosphate (ATP) and inorganic phosphate (Pi)-ATP exchange reactions were measured in the soleus (kCK = 0.30 ± 0.06 s(-1) and kATP = 0.11 ± 0.02 s(-1) , respectively) and in the medial gastrocnemius (kCK = 0.27 ± 0.06 s(-1) and kATP = 0.09 ± 0.03s(-1) , respectively) in 15 minutes per muscle group. The corresponding fluxes were FCK = 6.26 ± 1.28 µmol/g/s, FATP = 0.22 ± 0.05 µmol/g/s and FCK = 6.29 ± 1.66 µmol/g/s, FATP = 0.21 ± 0.07 µmol/g/s, for soleus and gastrocnemius, respectively. The hepatic ATP synthesis measurement was feasible in 24 minutes. CONCLUSION: The fast assessment of PCr-ATP and Pi-ATP exchange rates at 7T makes the 1D-ISIS ST sequence a promising tool for examining local resting-state metabolism in clinically acceptable measurement times.

Effects of carnosine supplementation on glucose metabolism: Pilot clinical trial.

OBJECTIVE: Carnosine is a naturally present dipeptide in humans and an over-the counter food additive. Evidence from animal studies supports the role for carnosine in the prevention and treatment of diabetes and cardiovascular disease, yet there is limited human data. This study investigated whether carnosine supplementation in individuals with overweight or obesity improves diabetes and cardiovascular risk factors. METHODS: In a double-blind randomized pilot trial in nondiabetic individuals with overweight and obesity (age 43 ± 8 years; body mass index 31 ± 4 kg/m(2) ), 15 individuals were randomly assigned to 2 g carnosine daily and 15 individuals to placebo for 12 weeks. Insulin sensitivity and secretion, glucose tolerance (oral glucose tolerance test), blood pressure, plasma lipid profile, skeletal muscle ((1) H-MRS), and urinary carnosine levels were measured. RESULTS: Carnosine concentrations increased in urine after supplementation (P < 0.05). An increase in fasting insulin and insulin resistance was hampered in individuals receiving carnosine compared to placebo, and this remained significant after adjustment for age, sex, and change in body weight (P = 0.02, P = 0.04, respectively). Two-hour glucose and insulin were both lower after carnosine supplementation compared to placebo in individuals with impaired glucose tolerance (P < 0.05). CONCLUSIONS: These pilot intervention data suggest that carnosine supplementation may be an effective strategy for prevention of type 2 diabetes.

CROP - The Clinico-Radiologico-Ophthalmological Paradox in Multiple Sclerosis: Are Patterns of Retinal and MRI Changes Heterogeneous and Thus Not Predictable?

BACKGROUND: To date, no direct scientific evidence has been found linking tissue changes in multiple sclerosis (MS) patients, such as demyelination, axonal destruction or gliosis, with either steady progression and/or stepwise accumulation of focal CNS lesions. Tissue changes such as reduction of the retinal nerve fiber layer (RNFL) and the total macular volume (TMV), or brain- and spinal cord atrophy indicates an irreversible stage of tissue destruction. Whether these changes are found in all MS patients, and if there is a correlation with clinical disease state, remains controversial. The objective of our study was to determine, whether there was any correlation between the RNFL or TMV of patients with MS, and: (1) the lesion load along the visual pathways, (2) the ratios and absolute concentrations of metabolites in the normal-appearing white matter (NAWM), (3) standard brain atrophy indices, (4) disease activity or (5) disease duration. METHODS: 28 MS patients (RRMS, n = 23; secondary progressive MS (SPMS), n = 5) with moderately-high disease activity or long disease course were included in the study. We utilised: (1) magnetic resonance imaging (MRI) and (2) -spectroscopy (MRS), both operating at 3 Tesla, and (3) high-resolution spectral domain-OCT with locked reference images and eye tracking mode) to undertake the study. RESULTS: There was no consistency in the pattern of CNS metabolites, brain atrophy indices and the RNFL/TMV between individuals, which ranged from normal to markedly-reduced levels. Furthermore, there was no strict correlation between CNS metabolites, lesions along the visual pathways, atrophy indices, RNFL, TMV, disease duration or disability. CONCLUSIONS: Based on the findings of this study, we recommend that the concept of 'clinico-radiologico paradox' in multiple sclerosis be extended to CROP-'clinico-radiologico-ophthalmological paradox'. Furthermore, OCT data of MS patients should be interpreted with caution.

No evidence of ectopic lipid accumulation in the pathophysiology of the acromegalic cardiomyopathy.

CONTEXT: PATIENTS with acromegaly frequently display disturbances of glucose and lipid metabolism, which might contribute to their increased cardiovascular risk. Because insulin resistance and increased lipolysis have been linked to ectopic lipid deposition, altered lipid accumulation in the liver and the myocardium might contribute to metabolic and cardiac complications in these patients. OBJECTIVE: The aim of this study was to investigate myocardial (MYCL) and hepatic lipid content (HCL), insulin sensitivity, and cardiac function in active acromegaly and after control of GH excess through transsphenoidal surgery. PATIENTS: Ten patients with newly diagnosed acromegaly (ACRO_active) were compared with 12 healthy controls (CON), matched for age, body mass index, and gender. In seven patients GH excess was controlled, and they were compared with their active state. METHODS: MYCL and HCL were assessed by (1)H-magnetic resonance spectroscopy, pericardial fat and cardiac function by (1)H-magnetic resonance imaging, and insulin sensitivity and secretion by an oral glucose tolerance test. RESULTS: Although MYCL tended to be lower, HCL was significantly lower in ACRO_active compared with CON (HCL: 1.2% ± 1.2% vs 4.3% ± 3.5% of (1)H-magnetic resonance spectroscopy signal, P < .02). Parameters of systolic function and hypertrophy were significantly increased in ACRO_active compared with CON, as were insulin secretion and resistance. After the control of GH excess, HCL and MYCL remained unchanged, but pericardial fat was increased in the patients in whom GH excess was controlled (from 11.6 ± 5.5 to 14.7 ± 6.2 cm(2), P = .02). CONCLUSION: Acromegaly represents a unique condition characterized by low myocardial and hepatic lipid content despite decreased insulin sensitivity, hyperinsulinemia, and hyperglycemia. Hence, ectopic lipid accumulation does not appear to contribute to cardiac morbidity, and increased lipid oxidation might counteract ectopic lipid accumulation in GH excess.