Reelin Regulates Developmental Desynchronization Transition of Neocortical Network Activity.

During the first and second stages of postnatal development, neocortical neurons exhibit a wide range of spontaneous synchronous activity (SSA). Towards the end of the second postnatal week, the SSA is replaced by a more sparse and desynchronized firing pattern. The developmental desynchronization of neocortical spontaneous neuronal activity is thought to be intrinsically generated, since sensory deprivation from the periphery does not affect the time course of this transition. The extracellular protein reelin controls various aspects of neuronal development through multimodular signaling. However, so far it is unclear whether reelin contributes to the developmental desynchronization transition of neocortical neurons. The present study aims to investigate the role of reelin in postnatal cortical developmental desynchronization using a conditional reelin knockout (RelncKO) mouse model. Conditional reelin deficiency was induced during early postnatal development, and Ca2+ recordings were conducted from organotypic cultures (OTCs) of the somatosensory cortex. Our results show that both wild type (wt) and RelncKO exhibited an SSA pattern during the early postnatal week. However, at the end of the second postnatal week, wt OTCs underwent a transition to a desynchronized network activity pattern, while RelncKO activity remained synchronous. This changing activity pattern suggests that reelin is involved in regulating the developmental desynchronization of cortical neuronal network activity. Moreover, the developmental desynchronization impairment observed in RelncKO was rescued when RelncKO OTCs were co-cultured with wt OTCs. Finally, we show that the developmental transition to a desynchronized state at the end of the second postnatal week is not dependent on glutamatergic signaling. Instead, the transition is dependent on GABAAR and GABABR signaling. The results suggest that reelin controls developmental desynchronization through GABAAR and GABABR signaling.

Catalytic Oxidation of CO and Benzene over Metal Nanoparticles Loaded on Hierarchical MFI Zeolite.

In order to obtain highly active catalytic materials for oxidation of carbon monoxide and volatile organic compounds (VOCs), monometallic platinum, copper, and palladium catalysts were prepared by using of two types of ZSM-5 zeolite as supports-parent ZSM-5 and the same one treated by HF and NH4F buffer solution. The catalyst samples, obtained by loading of platinum, palladium, and copper on ZSM-5 zeolite treated using HF and NH4F buffer solution, were more active in the reaction of CO and benzene oxidation compared with catalyst samples containing untreated zeolite. The presence of secondary mesoporosity played a positive role in increasing the catalytic activity due to improved reactant diffusion. The only exception was the copper catalysts in the reaction of CO oxidation, in which case the catalyst, based on untreated ZSM-5 zeolite, was more active. In this specific case, the key role is played by the oxidative state of copper species loaded on the ZSM-5 zeolites.

Reelin restricts dendritic growth of interneurons in the neocortex.

Reelin is a large secreted glycoprotein that regulates neuronal migration, lamination and establishment of dendritic architecture in the embryonic brain. Reelin expression switches postnatally from Cajal-Retzius cells to interneurons. However, reelin function in interneuron development is still poorly understood. Here, we have investigated the role of reelin in interneuron development in the postnatal neocortex. To preclude early cortical migration defects caused by reelin deficiency, we employed a conditional reelin knockout (RelncKO) mouse to induce postnatal reelin deficiency. Induced reelin deficiency caused dendritic hypertrophy in distal dendritic segments of neuropeptide Y-positive (NPY+) and calretinin-positive (Calr+) interneurons, and in proximal dendritic segments of parvalbumin-positive (Parv+) interneurons. Chronic recombinant Reelin treatment rescued dendritic hypertrophy in Relncko interneurons. Moreover, we provide evidence that RelncKO interneuron hypertrophy is due to presynaptic GABABR dysfunction. Thus, GABABRs in RelncKO interneurons were unable to block N-type (Cav2.2) Ca2+ channels that control neurotransmitter release. Consequently, the excessive Ca2+ influx through AMPA receptors, but not NMDA receptors, caused interneuron dendritic hypertrophy. These findings suggest that reelin acts as a 'stop-growth-signal' for postnatal interneuron maturation.

Reelin signaling modulates GABAB receptor function in the neocortex.

Reelin is a protein that is best known for its role in controlling neuronal layer formation in the developing cortex. Here, we studied its role for post-natal cortical network function, which is poorly explored. To preclude early cortical migration defects caused by Reelin deficiency, we used a conditional Reelin knock-out (RelncKO ) mouse, and induced Reelin deficiency post-natally. Induced Reelin deficiency caused hyperexcitability of the neocortical network in vitro and ex vivo. Blocking Reelin binding to its receptors ApoER2 and VLDLR resulted in a similar effect. Hyperexcitability in RelncKO organotypic slice cultures could be rescued by co-culture with wild-type organotypic slice cultures. Moreover, the GABAB receptor (GABAB R) agonist baclofen failed to activate and the antagonist CGP35348 failed to block GABAB Rs in RelncKO mice. Immunolabeling of RelncKO cortical slices revealed a reduction in GABAB R1 and GABAB R2 surface expression at the plasma membrane and western blot of RelncKO cortical tissue revealed decreased phosphorylation of the GABAB R2 subunit at serine 892 and increased phosphorylation at serine 783, reflecting receptor deactivation and proteolysis. These data show a role of Reelin in controlling early network activity, by modulating GABAB R function. Cover Image for this issue: https://doi.org/10.1111/jnc.15054.

Biolistic transfection and expression analysis of acute cortical slices.

BACKGROUND: Biolistic gene gun transfection has been used to transfect organotypic cultures (OTCs) or dissociated cultures in vitro. Here, we modified this technique to allow successful transfection of acute brain slices, followed by measurement of neuronal activity within a few hours. NEW METHOD: We established biolistic transfection of murine acute cortical slices to measure calcium signals. Acute slices are mounted on plasma/thrombin coagulate and transfected with a calcium sensor. Imaging can be performed within 4 h post transfection without affecting cell viability. RESULTS: Four hours after GCaMP6s transfection, acute slices display remarkable fluorescent protein expression level allowing to study spontaneous activity and receptor pharmacology. While optimal gas pressure (150 psi) and gold particle size used (1 µm) confirm previously published protocols, the amount of 5 µg DNA was found to be optimal for particle coating. COMPARISON WITH EXISTING METHODS: The major advantage of this technique is the rapid disposition of acute slices for calcium imaging. No transgenic GECI expressing animals or OTC for long periods are required. In acute slices, network interaction and connectivity are preserved. The method allows to obtain physiological readouts within 4 h, before functional tissue modifications might come into effect. Limitations of this technique are random transfection, low expression efficiency when using specific promotors, and preclusion or genetic manipulations that require a prolonged time before physiological changes become measurable, such as expression of recombinant proteins that require transport to distant subcellular localizations. CONCLUSION: The method is optimal for short-time investigation of calcium signals in acute slices.

Selective IUGR in dichorionic twins: what can Doppler assessment and growth discordancy say about neonatal outcomes?

OBJECTIVE: The aim of the present study was to assess, in a population of dichorionic twin pregnancies with selective growth restriction, the effect of inter-twin differences by use of Doppler velocimetry and fetal growth discordancy on perinatal outcomes. METHODS: This was a retrospective study including dichorionic twin pregnancies from January 2008 to December 2015 at the Department of Obstetrics and Gynecology of Fondazione MBBM. Only dichorionic twin pregnancies affected by selective intrauterine growth restriction (IUGR) delivering at ≥24 weeks were included in the study. RESULTS: We found that twin pregnancies with inter-twin estimated fetal weight (EFW) discordance ≥15% were significantly associated with a higher risk of preterm delivery before 32 (P=0.004) and 34 weeks (P=0.04). Similarly, twin pregnancies with inter-twin abdominal circumference (AC) discordance ≥30° centiles were associated with a higher rate of neonatal intensive care unit (NICU) admission (P=0.02), neonatal resuscitation (P=0.02) and adverse neonatal composite outcome (P=0.04). Of interest, when comparing twin pregnancies according to Doppler study, growth restricted twins had a higher rate of composite neonatal outcome and in multivariate analysis, an abnormal Doppler was an independent risk factor for this outcome. CONCLUSIONS: Our study associated growth discrepancy with specific pregnancy outcomes, according to defined cut-offs. In addition, we demonstrated that an abnormal umbilical artery Doppler is independently associated with a composite neonatal adverse outcome in growth restricted fetuses.

Osteonecrosis of the jaw in patients on bisphosphonate treatment. review of literature with contribution of a case of multiple myeloma.

In recent years, the incidence of osteonecrosis of the jaw (ONJ) as an unknown complication in patients receiving bisphosphonates (BP) has been on the increase. According to literature data it is in the range of 0.83% to 11.9%. ONJ has been mostly reported in patients with malignancies--mainly in multiple myeloma (MM) patients, followed by patients with bone metastases from breast and prostatic cancer. The view that is supported by a growing body of researchers in the discussion on the etiopathogenetic relationship between ONJ and BPs is that ONJ seems to be a class-specific side effect rather than a result of the use of a specific drug. The major risk factor for development of ONJ is not the BP type, but the time of their administration and accumulation in the bone structures. More than 70% of the ONJ patients report preceding dental problems. The immunosuppressive effects of chemo- and radiotherapy, the impaired bone remodeling resulting from corticoid therapy, the antiangiogenetic properties of thalidomide slow down the reparative processes in the oral cavity and appear as a predisposing factor for the development of ONJ. Possibilities for successful treatment are limited; conservative approaches and least surgery, if larger areas are involved, are recommended. Dental prophylaxis is of particular importance. We present a 66-year-old man with multiple myeloma, IgG, BJ(k), II A KC (after Durie and Salmon staging system). ONJ was diagnosed one year after the disease onset, during which the patient received chemotherapy and was administered concurrently 14 cycles of BPs (pamidronate/zolendronate). The diagnosis was based on clinical, radiologic and histological evidence. Surgical removal of the necrotic sequesters and antibiotic treatment produced a clinical improvement. This rare, refractory complication requires the joint efforts of hematologists, oncologists, and maxillofacial surgeons to diagnose, manage prophylactically and treat.