Quantum monitoring of cellular metabolic activities in single mitochondria.

Free radicals play a vital role in all kinds of biological processes including immune responses. However, free radicals have short lifetimes and are highly reactive, making them difficult to measure using current methods. Here, we demonstrate that relaxometry measurement, or T1, inherited from the field of diamond magnetometry can be used to detect free radicals in living cells with subcellular resolution. This quantum sensing technique is based on defects in diamond, which convert a magnetic signal into an optical signal, allowing nanoscale magnetic resonance measurements. We functionalized fluorescent nanodiamonds (FNDs) to target single mitochondria within macrophage cells to detect the metabolic activity. In addition, we performed measurements on single isolated mitochondria. We were able to detect free radicals generated by individual mitochondria in either living cells or isolated mitochondria after stimulation or inhibition.

Surgical treatment of hypothalamic hamartomas.

Hypothalamic hamartomas are aberrant masses, composed of abnormally distributed neurons and glia. Along endocrine and cognitive symptoms, they may cause epileptic seizures, including the specific gelastic and dacrystic seizures. Surgery is the treatment of drug-resistant hamartoma epilepsy, with associated positive results on endocrine, psychiatric, and cognitive symptoms. Recently, alternatives to open microsurgical treatment have been proposed. We review these techniques and compare their efficacy and safety. Open resection or disconnection of the hamartoma, either through pterional, transcallosal, or transventricular approach, leads to good epileptological control, but its high complication rate, up to 30%, limits its indications. The purely cisternal peduncular forms remain the only indication of open, pterional approach, while other strategies have been developed to overcome the neurological, endocrine, behavioral, or cognitive complications. Laser and radiofrequency thermocoagulation-based disconnection through robot-guided stereo-endoscopy has been proposed as an alternative to open microsurgical resection and stereotactic destruction. The goal is to allow safe and complete disconnection of a possibly complex attachment zone, through a single intraparenchymal trajectory which allows multiple laser or radiofrequency probe trajectory inside the ventricle. The efficacy was high, with 78% of favorable outcome, and the overall complication rate was 8%. It was especially effective in patients with isolated gelastic seizures and pure intraventricular hamartomas. Stereotactic radiosurgery has proved as efficacious and safer than open microsurgery, with around 60% of seizure control and a very low complication rate. Multiple stereotactic thermocoagulation showed very interesting results with 71% of seizure freedom and 2% of permanent complications. Stereotactic laser interstitial thermotherapy (LiTT) seems as effective as open microsurgery (from 76 to 81% of seizure freedom) but causes up to 20% of permanent complications. This technique has however been highly improved by targeting only the epileptogenic onset zone in the hamartoma, as shown on preoperative functional MRI, leading to an improvement of epilepsy control by 45% (92% of seizure freedom) with no postoperative morbidity. All these results suggest that the impact of the surgical procedure does not depend on purely technical matters (laser vs radiofrequency thermocoagulation or stereotactic vs robot-guided stereo-endoscopy) but relies on the understanding of the epileptic network, including inside the hamartoma, the aim being to plan an effective disconnection or lesion of the epileptogenic part while sparing the adjacent functional structures.

Nanodiamonds as multi-purpose labels for microscopy.

Nanodiamonds containing fluorescent nitrogen-vacancy centers are increasingly attracting interest for use as a probe in biological microscopy. This interest stems from (i) strong resistance to photobleaching allowing prolonged fluorescence observation times; (ii) the possibility to excite fluorescence using a focused electron beam (cathodoluminescence; CL) for high-resolution localization; and (iii) the potential use for nanoscale sensing. For all these schemes, the development of versatile molecular labeling using relatively small diamonds is essential. Here, we show the direct targeting of a biological molecule with nanodiamonds as small as 70 nm using a streptavidin conjugation and standard antibody labelling approach. We also show internalization of 40 nm sized nanodiamonds. The fluorescence from the nanodiamonds survives osmium-fixation and plastic embedding making them suited for correlative light and electron microscopy. We show that CL can be observed from epon-embedded nanodiamonds, while surface-exposed nanoparticles also stand out in secondary electron (SE) signal due to the exceptionally high diamond SE yield. Finally, we demonstrate the magnetic read-out using fluorescence from diamonds prior to embedding. Thus, our results firmly establish nanodiamonds containing nitrogen-vacancy centers as unique, versatile probes for combining and correlating different types of microscopy, from fluorescence imaging and magnetometry to ultrastructural investigation using electron microscopy.

Shape and crystallographic orientation of nanodiamonds for quantum sensing.

Nanodiamonds with dimensions down to a few tens of nanometers containing nitrogen-vacancy (NV) color centers have revealed their potential as powerful and versatile quantum sensors with a unique combination of spatial resolution and sensitivity. The NV centers allow transducing physical properties, such as strain, temperature, and electric or magnetic field, to an optical transition that can be detected in the single photon range. For example, this makes it possible to sense a single electron spin or a few nuclear spins by detecting their magnetic resonance. The location and orientation of these defects with respect to the diamond surface play a crucial role in interpreting the data and predicting their sensitivities. Despite its relevance, the geometry of these nanodiamonds has never been thoroughly investigated. Without accurate data, spherical models have been applied to interpret or predict results in the past. With the use of High Resolution Transmission Electron Microscopy (HR-TEM), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), we investigated nanodiamonds with an average hydrodynamic diameter of 25 nm (the most common type for quantum sensing) and found a flake-like geometry, with 23.2 nm and 4.5 nm being the average lateral and vertical dimensions. We have also found evidence for a preferred crystallographic orientation of the main facet in the (110) direction. Furthermore, we discuss the consequences of this difference in geometry on diamond-based applications. Shape not only influences the creation efficiency of nitrogen-vacancy centers and their quantum coherence properties (and thus sensing performance), but also the optical properties of the nanodiamonds, their interaction with living cells, and their surface chemistry.

Outcome of surgery in children with focal cortical dysplasia younger than 5 years explored by stereo-electroencephalography.

PURPOSE: Focal cortical dysplasia (FCD) is the most frequent etiology for drug-resistant epilepsy in young children. Complete removal of the lesion is mandatory to cure the epilepsy. Stereo-EEG (SEEG) is an excellent method to delimitate the zone to be resected in older children and adults. We studied its feasibility in younger children. METHODS: We retrospectively studied 19 children under 5 years of age who underwent SEEG between January 2009 and December 2012 and were subsequently operated on. FCD was diagnosed in all. We reviewed magnetic resonance imaging (MRI), electrophysiological and clinical data, as well as postoperative seizure outcome. We also included fluoro-deoxyglucose positron emission tomography (FDG-PET) studies, which had been systematically performed before invasive recording in 16 of the 19 children. RESULTS: The mean patient's age at the time of SEEG was 38.6 months, and the mean age at seizure onset was 8 months. Three patients had normal MRI. No SEEG-associated complications occurred. We were able to delineate the epileptogenic zone in all children, and electrode stimulation localized the motor area when necessary (12 patients). Hypometabolic areas on FDG-PET included the epileptogenic zone in 13 of the 16 children, with a lobar concordance in 9 (56 %) and the same anatomical extent in 6 (38 %). Twelve children subsequently underwent focal or sublobar resection, six had multilobar resection, and one had hemispherotomy. The etiology was FCD type 2 in 15 and FCD type 1 or type 3 in three children. Eighty-four percent of our population have remained seizure-free at a mean follow-up of 29 months (12-48 months). CONCLUSION: Although children with FCD can successfully undergo resective surgery without invasive EEG, poor seizure semiology at this age inclines to perform SEEG when the dysplastic lesion is ill-defined and/or the electroclinical correlation is unclear. In cases with normal imaging as well as with suspected huge malformations, as was the case in 52 % of our patients, we consider it to be indispensable.

Insular and insulo-opercular epilepsy in childhood: an SEEG study.

PURPOSE: In recent years, there have been series analysing the electro-clinical correlations of insular epilepsy in adult populations. In contrast, the ictal semiology in children with insular epilepsy is poorly described. Considering that early and successful surgery may greatly improve the cognitive outcome and quality of life, it is worthwhile to deepen our knowledge of insular epilepsy in children. METHODS: We retrospectively evaluated ten children with drug-resistant focal insular epilepsy who had been consecutively explored with stereoelectroencephalography (SEEG), followed by individually tailored resective surgery that included part of the insula in all cases. A detailed anatomo-electro-clinical analysis of non-invasive EEG and SEEG data was performed. At least one of the electrodes explored the insular cortex. SEEG analysis confirmed that the insular cortex was included in the ictal onset zone. RESULTS: Epilepsy onset was mostly during the first year of life, characterized by subtle seizures as well as spasms and myoclonic seizures. Later on, neurovegetative signs and asymmetric tonic and hypermotor seizures (HMS) dominated the ictal semiology. The epileptogenic zone was frequently wider than insular with frontal and central predominance. In eight patients, the tailored resection included a lesion. In seven patients, an Engel class 1 outcome as well as neuropsychological and behavioural improvement was obtained. CONCLUSIONS: SEEG is feasible and useful in children with drug-resistant insular epilepsy which is often characterized by autonomic symptoms as the initial symptoms and should be suspected in cases with HMS, asymmetric tonic seizures and even asymmetric spasms. Early propagation is mostly frontal and central. Analysis of a larger population is required to refine these findings.

Chloride-mediated inhibition of the ictogenic neurones initiating genetically-determined absence seizures.

Electroclinical investigations in human patients and experimental studies from genetic models demonstrated that spike-and-wave discharges (SWDs) associated with absence seizures have a cortical onset. In the Genetic Absence Epilepsy Rat from Strasbourg (GAERS), SWDs are initiated by the paroxysmal discharges of ictogenic pyramidal neurones located in the deep layers of the somatosensory cortex. However, the cellular and synaptic mechanisms that control the ictal discharges of seizure-initiating neurones remain unclear. Here, by the means of in vivo paired electroencephalographic (EEG) and intracellular recordings in the GAERS cortical focus, we explored the participation of the intracortical inhibitory system in the control of paroxysmal activities in ictogenic neurones. We found that their firing during EEG paroxysms was interrupted by the occurrence of hyperpolarizing synaptic events that reversed in polarity below action potential threshold. Intracellular injection of Cl(-) dramatically increased the amplitude of the paroxysmal depolarizations and the number of generated action potentials, strongly suggesting that the inhibitory synaptic potentials were mediated by GABA(A) receptors. Consistently, we showed that intracellularly recorded GABAergic interneurones fired, during seizures, shortly after (∼+8 ms) the discharge of ictogenic neurones and displayed a rhythmic bursting that coincided with the inhibitory synaptic events in neighbouring pyramidal ictogenic cells. In contrast with other forms of epilepsy, our findings suggest that paroxysmal activities in the cortical pyramidal cells initiating absence seizures are negatively controlled by a feedback Cl(-)-mediated inhibition likely resulting from the fast recurrent activation of intracortical GABAergic interneurones by the ictogenic cells themselves.

Unusual consequences of status epilepticus in Dravet syndrome.

Although status epilepticus (SE) affects the course of Dravet syndrome (DS), it rarely alters dramatically psychomotor outcome. We report an unusual pattern in 3 patients who following refractory SE lasting respectively 2, 7 and 12h experienced persistent and severe cognitive and motor deterioration. We compared these patients to published data and to personal experience in Necker hospital, to find links between severe outcome and clinical features such as treatment or duration of refractory SE. The key point was that anoxoischemic-like lesions appeared on MRI although cardiovascular function had remained stable. Therefore, neither hemodynamic failure, nor abnormalities of cardiac rhythm could explain the lesions and neurological worsening. For theoretical reasons the responsibility of therapy common for the 3 patients, e.g., barbiturates was suspected.

[Complications of prostaglandin E1 treatment of congenital heart disease in paediatric medical intensive care]. / Complications du traitement par prostaglandines E1 des cardiopathies congénitales en réanimation médicale pédiatrique.

The authors undertook a retrospective study of the modes of prescription, the tolerance and efficacy of prostaglandin E1 in 62 consecutive neonates with congenital heart disease (average Age 1.6 days: 35 boys: weight: 3.1 +/- 0.6 Kg) admitted to the paediatric intensive care unit of Nancy University Hospital between 1998 and 2002. The infusion time and cumulative dosage were 134 +/- 112 (6-480) hours and 111 +/- 94 (4-396) microg/Kg respectively. The side effects that were observed were: Apnoea (19%), abdominal distension (16%), bradycardia (13%), enterocolitis (6.5%), hypotension (6.5%), vomiting (5%), fever (1.6%) and skin rash (1.6%). Gastrointestinal disturbances are associated with a low body weight (p<0.04), to prolonged treatment (p<0.02) with no influence of initial or cumulative dosages (P=NS), with respiratory assistance (p<0.03) and longer hospital stay (p<0.01). Hypotension was commoner in cases of poor neonatal adaptation. Mortality was correlated with severe initial acidosis (p<0.02), a low Apgar score, the initial prolonged use of high doses of prostaglandin (p<0.04), and the presence of severe valvular aortic stenosis or hypoplasia of the left heart (p<0.002). The authors conclude that treatment with prostaglandin is effective in the majority of cases despite the use of low maintenance doses (0.01 microg/Kg/min). Gastrointestinal disturbances favourised by the perinatal context, the cardiac disease, and prolonged treatment are significant factors for morbidity and mortality. The beneficial role of early neonatal enteral feeding was not demonstrated in this high risk population.