Single dose creatine improves cognitive performance and induces changes in cerebral high energy phosphates during sleep deprivation

The inverse effects of creatine supplementation and sleep deprivation on high energy phosphates, neural creatine, and cognitive performances suggest that creatine is a suitable candidate for reducing the negative effects of sleep deprivation. With this, the main obstacle is the limited exogenous uptake by the central nervous system (CNS), making creatine only effective over a long-term diet of weeks. Thus far, only repeated dosing of creatine over weeks has been studied, yielding detectable changes in CNS levels. Based on the hypothesis that a high extracellular creatine availability and increased intracellular energy consumption will temporarily increase the central creatine uptake, subjects were orally administered a high single dose of creatinemonohydrate (0.35 g/kg) while performing cognitive tests during sleep deprivation. Two consecutive 31P-MRS scans, 1H-MRS, and cognitive tests were performed each at evening baseline, 3, 5.5, and 7.5 h after single dose creatine (0.35 g/kg) or placebo during sub-total 21 h sleep deprivation (SD). Our results show that creatine induces changes in PCr/Pi, ATP, tCr/tNAA, prevents a drop in pH level, and improves cognitive performance and processing speed. These outcomes suggest that a high single dose of creatine can partially reverse metabolic alterations and fatigue-related cognitive deterioration.

Studies of ⁶Li-NMR properties in different salt solutions in low magnetic fields

In this article we report the longitudinal relaxation times (T(1)) of various (6)Li salts ((6)LiI, (6)LiCl and (6)LiNO(3)) in D(2)O and H(2)O, measured in low magnetic fields (B(0)=3.5mT). This investigation serves the purpose of clarifying the relaxation behavior of different (6)Li solutions and different concentrations. The measurement were undertaken to establish a framework for future applications of hyperpolarized (6)Li in medical imaging, biological studies and investigations of lithium ion batteries. Time will pass during the transport of hyperpolarized lithium ions to the sample, which leads to a polarization loss. In order to store polarization as long as possible, it is necessary to examine which (6)Li salt solution has the longest relaxation time T(1). Longitudinal relaxation times of (6)Li salts in D(2)O and H(2)O were investigated as a function of concentration and the most extended T(1) was found for (6)LiI in D(2)O and H(2)O. In agreement with the theory the relaxation time T(1) of all (6)Li salts increase with decreasing concentration. In the case of (6)LiI in H(2)O an inverse behavior was observed. We assume that the prolonged T(1) times occur due to formation of (6)LiOH upon the solution of (6)LiI in H(2)O, which settles as a precipitate. By diluting the solution, the precipitate continuously dissolves and approaches T(1) of (6)LiOH (T(1)∼28s), leading to a shorter T(1) relaxation time.

Trace analysis by low-field NMR: breaking the sensitivity limit

Sensitivity poses a persistent challenge to NMR spectroscopy and magnetic resonance imaging (MRI). Nonhydrogenative para-hydrogen induced polarization (NH-PHIP) has recently emerged as an efficient method to substantially increase the sensitivity of high-field NMR. Here, we report the feasibility of applying NH-PHIP in the low-field NMR. A trace amount of pyridine of just a few nanoliters ( approximately 12 nmol) in a 0.4 mL NMR sample (a concentration of 31 microM or 10(16)/cm(3)) could be measured in a single scan by NH-PHIP. There is a striking difference in the signal-to-noise ratio (SNR) between thermal prepolarization and NH-PHIP: The SNR of the prepolarized (1)H NMR signal decreases linearly with decreasing (1)H concentration ([(1)H]) while the SNR in NH-PHIP experiments first increases with decreasing [(1)H], then remains constant over 2 orders of magnitude, and finally decreases linearly with decreasing [(1)H]. A hitherto unknown potential opens up for trace analysis by low-field NMR in the bio-, chemical, and material sciences.