After the landmark studies reporting changes in the cerebral metabolic rate of glucose (CMR Glc ) in excess of those in oxygen (CMR O2 ) during physiological stimulation, several studies have examined the fate of the extra carbon taken up by the brain, reporting a wide range of changes in brain lactate from 20% to 250%. The present study reports functional magnetic resonance spectroscopy measurements at 7 Tesla using the enhanced sensitivity to study a small cohort (n 5 6). Small increases in lactate (19% 6 4%, P < 0.05) and glutamate (4% 6 1%, P < 0.001) were seen within the first 2 min of activation. With the exception of glucose (12% 6 5%, P < 0.001), no other metabolite concentration changes beyond experimental error were significantly observed. Therefore, the present study confirms that lactate and glutamate changes during physiological stimulation are small (i.e. below 20%) and shows that the increased sensitivity allows reproduction of previous results with fewer subjects. In addition, the initial rate of glutamate and lactate concentration increases implies an increase in CMR O2 that is slightly below that of CMR Glc during the first 1-2 min of activation. V V C 2013 Wiley Periodicals, Inc.
Proton T 1 relaxation times of metabolites in the human brain have not previously been published at 7 T. In this study, T 1 values of CH 3 and CH 2 group of N-acetylaspartate and total creatine as well as nine other brain metabolites were measured in occipital white matter and gray matter at 7 T using an inversion-recovery technique combined with a newly implemented semi-adiabatic spin-echo full-intensity acquired localized spectroscopy sequence (echo time 5 12 ms). The mean T 1 values of metabolites in occipital white matter and gray matter ranged from 0.9 to 2.2 s. Among them, the T 1 of glutathione, scylloinositol, taurine, phosphorylethanolamine, and N-acetylaspartylglutamate were determined for the first time in the human brain. Significant differences in T 1 between white matter and gray matter were found for water (228%), total choline (214%), N-acetylaspartylglutamate (229%), N-acetylaspartate (14%), and glutamate (18%). An increasing trend in T 1 was observed when compared with previously reported values of N-acetylaspartate (CH 3 ), total creatine (CH 3 ), and total choline at 3 T. However, for N-acetylaspartate (CH 3 ), total creatine, and total choline, no substantial differences compared to previously reported values at 9.4 T were discernible. The T 1 values reported here will be useful for the quantification of metabolites and signal-to-noise optimization in human brain at 7 T. Magn Reson Med 69:931-936, 2013. V C 2012 Wiley Periodicals, Inc.
GCLC high-risk genotypes are associated with low [GSHmPFC], highlighting that GCLC polymorphisms should be considered in pathology studies of cerebral GSH. Low brain GSH levels are related to low peripheral oxidation status in controls but with high oxidation status in patients, pointing to a dysregulated GSH homeostasis in early psychosis patients. GCLC polymorphisms and disease associated correlations between brain GSH and Glu levels may allow patients stratification.
The present work is a pioneer study on the paracrine activity of bone grafts. The findings suggest that cortical bone chips release soluble signals that can modulate differentiation of mesenchymal cells in vitro at least partially involving TGF-β signaling.
Purpose: The macromolecule signal plays a key role in the precision and the accuracy of the metabolite quantification in short-TE 1 H MR spectroscopy. Macromolecules have been reported at 1.5 Tesla (T) to depend on the cerebral studied region and to be age specific. As metabolite concentrations vary locally, information about the profile of the macromolecule signal in different tissues may be of crucial importance. Methods: The aim of this study was to investigate, at 7T for healthy subjects, the neurochemical profile differences provided by macromolecule signal measured in two different tissues in the occipital lobe, predominantly composed of white matter tissue or of grey matter tissue. Results: White matter-rich macromolecule signal was relatively lower than the gray matter-rich macromolecule signal from 1.5 to 1.8 ppm and from 2.3 to 2.5 ppm with mean difference over these regions of 7% and 12% (relative to the reference peak at 0.9 ppm), respectively. The neurochemical profiles, when using either of the two macromolecule signals, were similar for 11 reliably quantified metabolites (CRLB < 20%) with relatively small concentration differences (< 0.3 mmol/g), except Glu (6 0.8 mmol/g). Conclusion: Given the small quantification differences, we conclude that a general macromolecule baseline provides a sufficiently accurate neurochemical profile in occipital lobe at 7T in healthy human brain. Magn Reson Med 72:934-940, 2014. V C 2013 Wiley Periodicals, Inc.
The aim of this study was to evaluate the difference between a 5-day and a 1-day postoperative course of antibiotic on the incidence of infection after mandibular fractures involving the alveolus. Sixty-two patients with fractures of the mandible involving the dentoalveolar region were randomly assigned to 2 groups, both of which were given amoxicillin/clavulanic acid 1.2 g intravenously every 8 h from admission until 24 h postoperatively. The 5-day group were then given amoxicillin/clavulanic acid 625 mg orally every 8 h for another 4 days. The 1-day group was given an oral placebo at the same intervals. Follow-up appointments were 1, 2, 4, 6, 12 weeks and 6 months postoperatively. Development of an infection was the primary end point. Fifty-nine of the 62 patients completed this study. Six of the 30 patients in the 5-day group (20%) and 6 out of the 29 in the 1-day group (21%) developed local wound infections. Three of the 6 in the 1-day group developed purulent discharge and swelling. One patient in the 5-day group developed a rash on the trunk. There were no significant differences in the incidence of infection or side effects between the groups. In fractures of the mandible involving the alveolus, a 1-day postoperative course of antibiotic is as effective in preventing infective complications as a 5-day regimen.
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