Ultrafast in vivo microwave irradiation for enhanced metabolic stability of brain biopsy samples during HRMAS NMR analysis.

High resolution magic-angle spinning (HRMAS) NMR spectroscopy is a well established technique for ex vivo metabolite investigations but experimental factors such as ischemic delay or mechanical stress due to continuous spinning deserve further investigations. Cortical brain samples from rats that underwent ultrafast in vivo microwave irradiation (MWp group) were compared to similar samples that underwent standard nitrogen freezing with and without exposure to domestic microwaves (FN and FN+MWd groups). One dimensional (1)H HRMAS NMR spectra were acquired and 16 metabolites of interest were quantified. Within each group 3 samples underwent long lasting acquisition (up to 15 h). Statistically significant differences in metabolite concentrations were observed between groups for metabolites associated to post mortem biochemical changes and/or anaerobic glycolysis including several neurotransmitters. Spectral assessment over time showed a drastic reduction of biochemical variations in both MW groups. Only 2/16 metabolites exhibited significant signal variations after 15 h of continuous spinning and acquisition in the MWp group. This number increased to 10 in the FN group. We confirmed limited anaerobic metabolism and post mortem degradation after ultra fast in vivo MW irradiation. Furthermore, spectra obtained after MWp and MWd irradiation exhibited an extremely stable spectral pattern over extended periods of continuous acquisition.

Prefrontal cortex recruitment during naturalistic remote memory: a factorial block-event fMRI study.

Most classical neuroimaging studies of human memory require the subject to follow task instructions, discriminate stimuli, make a decision and, finally, press a button to respond. To which extent does such a cognitive sequence influence neural correlates of recognition memory especially with respect to the prefrontal cortex (PFC) is not clear yet. We set up a naturalistic recognition task. Personal photographs were mixed with photographs from family albums of people who were not known to the participant. The subjects alternated a recognition task (recognition and response) with a mere observational one (simple recognition). This factorial block-event functional MRI design allowed us to disentangle the regions related to memory (personal photographs vs. distracters under both conditions) from those related to the response (responding vs. observing) as well as to examine the interaction between the two factors. Only medial and left orbito-frontal regions were transiently active during successful recognition in the two task conditions. Memory and responding interacted in the left lateral PFC within the middle and inferior gyrus. These regions were more active for personal photographs than for distracters only when the subject had to respond. Sustained activations spread bilaterally whatever the task. Such a design that encompasses personal photographs, an observation period for recognition as well as a mixed-design may have led to a better isolation of the neural network underlying remote autobiographical memory. Recruitment within the PFC during retrieval was only limited to its medial and left anterior parts. Sustained activation did not differ between the discrimination and the observation period. This original design might be valuable for further dissociation between decision, self, autobiographical memory and the PFC.

[Influence of seasons on risk of flare-up of systemic lupus: retrospective study of 66 patients]. / Influence de la saison sur le risque de poussée systémique du lupus: étude rétrospective de 66 patients.

PURPOSE: To establish the possible connection between visceral, arthro-cutaneous and biological spreading of systemic lupus (SL) and hours of sunlight. MATERIAL AND METHODS: Retrospective study of 66 SL patients, consisting of 52 visceral and 14 arthro-cutaneous cases taking into account the chronological pattern of each new aggravation, based on 480 clinical records. RESULTS: Increased frequency in visceral aggravation was observed in the post-summer period (August-January) (n = 57), as compared with the pre-summer period (February-July) (n = 25) (RR = 1.75, P = 0.006). This post-summer visceral aggravation was correlated with cutaneous affection (RR = 4.18) and absence of previous corticotherapy (RR = 3.97). Visceral and arthro-cutaneous aggravations taken together revealed a more disturbed immune balance pattern in the post-summer period (anti-dsDNA: 30 versus 25.1 IU/L [P = 0.07]; C3: 0.83 vs 0.921 IU/L [P = 0.05]; C4: 0.146 vs 0.183 [P = 0.05]), providing evidence of greater severity. Moderate thrombopenia (50-120 10(9)/L) accompanying visceral SL with antiphospholipids (n = 33) was more frequent during the post-summer period, even in the absence of aggravation (P = 0.03). The quarterly distribution of visceral aggravations was correlated with average hours of sunlight in the preceding quarter (P = 0.01). CONCLUSION: There is a post-summer increase in the frequency and severity of visceral SL spreading correlated to cutaneous exacerbation and sunlight.