Evidence for Two Subpopulations of Cerebrospinal Fluid-Contacting Neurons with Opposite GABAergic Signaling in Adult Mouse Spinal Cord.

Spinal cerebrospinal fluid-contacting neurons (CSF-cNs) form an evolutionary conserved bipolar cell population localized around the central canal of all vertebrates. CSF-cNs were shown to express molecular markers of neuronal immaturity into adulthood; however, the impact of their incomplete maturation on the chloride (Cl-) homeostasis as well as GABAergic signaling remains unknown. Using adult mice from both sexes, in situ hybridization revealed that a proportion of spinal CSF-cNs (18.3%) express the Na+-K+-Cl- cotransporter 1 (NKCC1) allowing intracellular Cl- accumulation. However, we did not find expression of the K+-Cl- cotransporter 2 (KCC2) responsible for Cl- efflux in any CSF-cNs. The lack of KCC2 expression results in low Cl- extrusion capacity in CSF-cNs under high Cl- load in whole-cell patch clamp. Using cell-attached patch clamp allowing recordings with intact intracellular Cl- concentration, we found that the activation of ionotropic GABAA receptors (GABAA-Rs) induced both depolarizing and hyperpolarizing responses in CSF-cNs. Moreover, depolarizing GABA responses can drive action potentials as well as intracellular calcium elevations by activating voltage-gated calcium channels. Blocking NKCC1 with bumetanide inhibited the GABA-induced calcium transients in CSF-cNs. Finally, we show that metabotropic GABAB receptors have no hyperpolarizing action on spinal CSF-cNs as their activation with baclofen did not mediate outward K+ currents, presumably due to the lack of expression of G-protein-coupled inwardly rectifying potassium (GIRK) channels. Together, these findings outline subpopulations of spinal CSF-cNs expressing inhibitory or excitatory GABAA-R signaling. Excitatory GABA may promote the maturation and integration of young CSF-cNs into the existing spinal circuit.

Rescue of Normal Excitability in LGI1-Deficient Epileptic Neurons.

Leucine-rich glioma inactivated 1 (LGI1) is a glycoprotein secreted by neurons, the deletion of which leads to autosomal dominant lateral temporal lobe epilepsy. We previously showed that LGI1 deficiency in a mouse model (i.e., knock-out for LGI1 or KO-Lgi1) decreased Kv1.1 channel density at the axon initial segment (AIS) and at presynaptic terminals, thus enhancing both intrinsic excitability and glutamate release. However, it is not known whether normal excitability can be restored in epileptic neurons. Here, we show that the selective expression of LGI1 in KO-Lgi1 neurons from mice of both sexes, using single-cell electroporation, reduces intrinsic excitability and restores both the Kv1.1-mediated D-type current and Kv1.1 channels at the AIS. In addition, we show that the homeostatic-like shortening of the AIS length observed in KO-Lgi1 neurons is prevented in neurons electroporated with the Lgi1 gene. Furthermore, we reveal a spatial gradient of intrinsic excitability that is centered on the electroporated neuron. We conclude that expression of LGI1 restores normal excitability through functional Kv1 channels at the AIS.SIGNIFICANCE STATEMENT The lack of leucine-rich glioma inactivated 1 (LGI1) protein induces severe epileptic seizures that leads to death. Enhanced intrinsic and synaptic excitation in KO-Lgi1 mice is because of the decrease in Kv1.1 channels in CA3 neurons. However, the conditions to restore normal excitability profile in epileptic neurons remain to be defined. We show here that the expression of LGI1 in KO-Lgi1 neurons in single neurons reduces intrinsic excitability, and restores both the Kv1.1-mediated D-type current and Kv1.1 channels at the axon initial segment (AIS). Furthermore, the homeostatic shortening of the AIS length observed in KO-Lgi1 neurons is prevented in neurons in which the Lgi1 gene has been rescued. We conclude that LGI1 constitutes a critical factor to restore normal excitability in epileptic neurons.

The downregulation of Kv1 channels in Lgi1-/-mice is accompanied by a profound modification of its interactome and a parallel decrease in Kv2 channels.

In animal models of LGI1-dependent autosomal dominant lateral temporal lobe epilepsy, Kv1 channels are downregulated, suggesting their crucial involvement in epileptogenesis. The molecular basis of Kv1 channel-downregulation in LGI1 knock-out mice has not been elucidated and how the absence of this extracellular protein induces an important modification in the expression of Kv1 remains unknown. In this study we analyse by immunofluorescence the modifications in neuronal Kv1.1 and Kv1.2 distribution throughout the hippocampal formation of LGI1 knock-out mice. We show that Kv1 downregulation is not restricted to the axonal compartment, but also takes place in the somatodendritic region and is accompanied by a drastic decrease in Kv2 expression levels. Moreover, we find that the downregulation of these Kv channels is associated with a marked increase in bursting patterns. Finally, mass spectrometry uncovered key modifications in the Kv1 interactome that highlight the epileptogenic implication of Kv1 downregulation in LGI1 knock-out animals.

Genetic Variant of DNAM-1 rs763361 C>T Is Associated with Ankylosing Spondylitis in a Mexican Population.

DNAM-1 (CD226) is an activating receptor expressed in CD8+ T cells, NK cells, and monocytes. It has been reported that two SNPs in the DNAM-1 gene, rs763361 C>T and rs727088 G>A, have been associated with different autoimmune diseases; however, the role of DNAM-1 in ankylosing spondylitis has been less studied. For this reason, we focused on the study of these two SNPs in association with ankylosing spondylitis. For this, 34 patients and 70 controls were analyzed using endpoint PCR with allele-specific primers. Our results suggest that rs763361 C>T is involved as a possible protective factor under the CT co-dominant model (OR = 0.34, 95% CI = 0.13-0.88, p = 0.022) and the CT + TT dominant model (OR = 0.39, 95% CI = 0.17-0.90, p = 0.025), while rs727088 G>A did not show an association with the disease in any of the inheritance models. When analyzing the relationships of the haplotypes, we found that the T + A haplotype (OR = 0.31, 95% CI = 0.13-0.73, p = 0.0083) is a protective factor for developing the disease. In conclusion, the CT and CT + TT variants of rs763361 C>T and the T + A haplotype were considered as protective factors for developing ankylosing spondylitis.

Dysfunctional serotonergic neuron-astrocyte signaling in depressive-like states.

Astrocytes play crucial roles in brain homeostasis and are regulatory elements of neuronal and synaptic physiology. Astrocytic alterations have been found in Major Depressive Disorder (MDD) patients; however, the consequences of astrocyte Ca2+ signaling in MDD are poorly understood. Here, we found that corticosterone-treated juvenile mice (Cort-mice) showed altered astrocytic Ca2+ dynamics in mPFC both in resting conditions and during social interactions, in line with altered mice behavior. Additionally, Cort-mice displayed reduced serotonin (5-HT)-mediated Ca2+ signaling in mPFC astrocytes, and aberrant 5-HT-driven synaptic plasticity in layer 2/3 mPFC neurons. Downregulation of astrocyte Ca2+ signaling in naïve animals mimicked the synaptic deficits found in Cort-mice. Remarkably, boosting astrocyte Ca2+ signaling with Gq-DREADDS restored to the control levels mood and cognitive abilities in Cort-mice. This study highlights the important role of astrocyte Ca2+ signaling for homeostatic control of brain circuits and behavior, but also reveals its potential therapeutic value for depressive-like states.

The impact of metastatic sites on survival Rates and predictors of extended survival in patients with metastatic pancreatic cancer.

BACKGROUND OBJECTIVES: The aim of this study was to determine the role of site-specific metastatic patterns over time and assess factors associated with extended survival in metastatic PDAC. Half of all patients with pancreatic ductal adenocarcinoma (PDAC) present with metastatic disease. The site of metastasis plays a crucial role in clinical decision making due to its prognostic value. METHODS: We examined 56,757 stage-IV PDAC patients from the National Cancer Database (2016-2019), categorizing them by metastatic site: multiple, liver, lung, brain, bone, carcinomatosis, or other. The site-specific prognostic value was assessed using log-rank tests while time-varying effects were assessed by Aalen's linear hazards model. Factors associated with extended survival (>3years) were assessed with logistic regression. RESULTS: Median overall survival (mOS) in patients with distant lymph node-only metastases (9.0 months) and lung-only metastases (8.1 months) was significantly longer than in patients with liver-only metastases (4.6 months, p < 0.001). However, after six months, the metastatic site lost prognostic value. Logistic regression identified extended survivors (3.6 %) as more likely to be younger, Hispanic, privately insured, Charlson-index <2, having received chemotherapy, or having undergone primary or distant site surgery (all p < 0.001). CONCLUSION: While synchronous liver metastases are associated with worse outcomes than lung-only and lymph node-only metastases, this predictive value is diminished after six months. Therefore, treatment decisions beyond this time should not primarily depend on the metastatic site. Extended survival is possible in a small subset of patients with favorable tumor biology and good conditional status, who are more likely to undergo aggressive therapies.

Non-fitness status of peripheral NK cells defined by decreased NKp30 and perforin, and increased soluble B7H6, in cervical cancer patients.

The NKp30 receptor is one of the three natural cytotoxic receptors reported in NK cells. This receptor is codified by the NCR3 gene, which encodes three isoforms, a consequence of the alternative splicing of exon 4. A greater expression of the three isoforms (A, B, and C), along with low levels of the NKp30 ligand B7H6, has been reported as a positive prognostic factor in different cancer types. Here, in patients with cervical cancer and precursor lesions, we report an altered immune-phenotype, characterized by non-fitness markers, that correlated with increased disease stage, from CIN 1 to FIGO IV. While overall NK cell numbers increased, loss of NKp30+ NK cells, especially in the CD56dim subpopulation, was found. Perforin levels were decreased in these cells. Decreased expression of the NKp30 C isoform and overexpression of soluble B7H6 was found in cervical cancer patients when compared against healthy subjects. PBMCs from healthy subjects downregulated NKp30 isoforms after co-culture with B7H6-expressing tumour cells. Taken together, these findings describe a unique down-modulation or non-fitness status of the immune response in cervical cancer, the understanding of which will be important for the design of novel immunotherapies against this disease.

Patient-derived antibodies reveal the subcellular distribution and heterogeneous interactome of LGI1.

Autoantibodies against leucine-rich glioma-inactivated 1 (LGI1) occur in patients with encephalitis who present with frequent focal seizures and a pattern of amnesia consistent with focal hippocampal damage. To investigate whether the cellular and subcellular distribution of LGI1 may explain the localization of these features, and hence gain broader insights into LGI1's neurobiology, we analysed the detailed localization of LGI1 and the diversity of its protein interactome, in mouse brains using patient-derived recombinant monoclonal LGI1 antibodies. Combined immunofluorescence and mass spectrometry analyses showed that LGI1 is enriched in excitatory and inhibitory synaptic contact sites, most densely within CA3 regions of the hippocampus. LGI1 is secreted in both neuronal somatodendritic and axonal compartments, and occurs in oligodendrocytic, neuro-oligodendrocytic and astro-microglial protein complexes. Proteomic data support the presence of LGI1-Kv1-MAGUK complexes, but did not reveal LGI1 complexes with postsynaptic glutamate receptors. Our results extend our understanding of regional, cellular and subcellular LGI1 expression profiles and reveal novel LGI1-associated complexes, thus providing insights into the complex biology of LGI1 and its relationship to seizures and memory loss.

Advances in Osteosarcoma.

PURPOSE OF REVIEW: This article gives a brief overview of the most recent developments in osteosarcoma treatment, including targeting of signaling pathways, immune checkpoint inhibitors, drug delivery strategies as single or combined approaches, and the identification of new therapeutic targets to face this highly heterogeneous disease. RECENT FINDINGS: Osteosarcoma is one of the most common primary malignant bone tumors in children and young adults, with a high risk of bone and lung metastases and a 5-year survival rate around 70% in the absence of metastases and 30% if metastases are detected at the time of diagnosis. Despite the novel advances in neoadjuvant chemotherapy, the effective treatment for osteosarcoma has not improved in the last 4 decades. The emergence of immunotherapy has transformed the paradigm of treatment, focusing therapeutic strategies on the potential of immune checkpoint inhibitors. However, the most recent clinical trials show a slight improvement over the conventional polychemotherapy scheme. The tumor microenvironment plays a crucial role in the pathogenesis of osteosarcoma by controlling the tumor growth, the metastatic process and the drug resistance and paved the way of new therapeutic options that must be validated by accurate pre-clinical studies and clinical trials.

Molecular landscape of BoNT/B bound to a membrane-inserted synaptotagmin/ganglioside complex.

Botulinum neurotoxin serotype B (BoNT/B) uses two separate protein and polysialoglycolipid-binding pockets to interact with synaptotagmin 1/2 and gangliosides. However, an integrated model of BoNT/B bound to its neuronal receptors in a native membrane topology is still lacking. Using a panel of in silico and experimental approaches, we present here a new model for BoNT/B binding to neuronal membranes, in which the toxin binds to a preassembled synaptotagmin-ganglioside GT1b complex and a free ganglioside allowing a lipid-binding loop of BoNT/B to interact with the glycone part of the synaptotagmin-associated GT1b. Furthermore, our data provide molecular support for the decrease in BoNT/B sensitivity in Felidae that harbor the natural variant synaptotagmin2-N59Q. These results reveal multiple interactions of BoNT/B with gangliosides and support a novel paradigm in which a toxin recognizes a protein/ganglioside complex.

A non-clinical and clinical IUCLID database for 530 pharmaceuticals (part I): Methodological aspects of its development.

A new IUCLID database is provided containing results from non-clinical animal studies and human information for 530 approved drugs. The database was developed by extracting data from pharmacological reviews of repeat-dose, carcinogenicity, developmental, and reproductive toxicity studies. In the database, observed and no-observed effects are linked to the respective effect levels, including information on severity/incidence and transiency/reversibility. It also includes some information on effects in humans, that were extracted from relevant sections of standard product labels of the approved drugs. The database is complemented with a specific ontology for reporting effects that was developed as an improved version of the Ontology Lookup Service's mammalian and human phenotype ontologies and includes different hierarchical levels. The developed ontology contains novel and unique standardized terms, including ontological terms for reproductive and endocrine effects. The database aims to facilitate correlation and concordance analyses based on the link between observed and no-observed effects and their respective effect levels. In addition, it offers a robust dataset on drug information for the pharmaceutical industry and research. The reported ontology supports the analyses of toxicological information, especially for reproductive and endocrine endpoints and can be used to encode legacy data or develop additional ontologies. The new database and ontology can be used to support the development of alternative non-animal approaches, to elucidate mechanisms of toxicity, and to analyse human relevance. The new IUCLID database is provided free of charge at https://iuclid6.echa.europa.eu/us-fda-toxicity-data.

Deleted genes associated with obesity in Mexican patients diagnosed with nonalcoholic fatty liver disease.

AIM: Nonalcoholic fatty liver disease (NAFLD) is a complex metabolic condition in which both lifestyle and genetic factors have a pathogenic role. The LEP gene encodes leptin, which regulates appetite, body weight, and several metabolic functions. Proopiomelanocortin (POMC), regulates food intake and energy balance. The aim of the study was to determine partial or complete deletions of genes associated with obesity in patients diagnosed with NAFLD. MATERIAL AND METHODS: Blood samples and DNA from 43 individuals diagnosed with NAFLD by ultrasonographic technique (Fibroscan) were obtained. The partial or complete deletions of genes were determined by MLPA (Multiplex Ligation-dependent Probe Amplification) using the SALSA probemix P220-B2 Obesity only on 43 individuals. Fifty blood samples from healthy individuals were included. RESULTS: Eleven out of 43 individuals analyzed by MLPA presented some deletion of the genes analyzed: six were female and five were male. The partial or complete deletion of the LEPR and POMC genes was observed in eight patients (18.6%), SIM1 in six patients (13.9%), GRIK2 and SH2B1 in two patients (4.7%), SEZGL2 in four patients (9.3%), and MCR4 in one patient (2.3%). CONCLUSION: Partial deletion was observed in LEPR, POMC, SIM1, GRIK2, SH2B1, SEZGL2, and MCR4 genes in 26% of the cases, and we suggest that these alterations probably has a potential relationship for the development of NAFLD.

Gangliosides interact with synaptotagmin to form the high-affinity receptor complex for botulinum neurotoxin B.

Botulinum neurotoxin type B (BoNT/B) recognizes nerve terminals by binding to 2 receptor components: a polysialoganglioside, predominantly GT1b, and synaptotagmin 1/2. It is widely thought that BoNT/B initially binds to GT1b then diffuses in the plane of the membrane to interact with synaptotagmin. We have addressed the hypothesis that a GT1b-synaptotagmin cis complex forms the BoNT/B receptor. We identified a consensus glycosphingolipid-binding motif in the extracellular juxtamembrane domain of synaptotagmins 1/2 and confirmed by Langmuir monolayer, surface plasmon resonance, and circular dichroism that GT1b interacts with synaptotagmin peptides containing this sequence, inducing α-helical structure. Molecular modeling and tryptophan fluorescence spectroscopy were consistent with the intertwining of GT1b and synaptotagmin, involving cis interactions between the oligosaccharide and ceramide moieties of GT1b and the juxtamembrane and transmembrane domains of synaptotagmin, respectively. Furthermore, a point mutation on synaptotagmin, located outside of the BoNT/B-binding segment, inhibited GT1b binding and blocked GT1b-induced potentiation of BoNT/B binding to synaptotagmin-expressing cells. Our findings are consistent with a model in which a preassembled GT1b-synaptotagmin complex constitutes the high-affinity BoNT/B receptor.

Distinctive binding properties of human monoclonal LGI1 autoantibodies determine pathogenic mechanisms.

Autoantibodies against leucine-rich glioma inactivated 1 (LGI1) are found in patients with limbic encephalitis and focal seizures. Here, we generate patient-derived monoclonal antibodies (mAbs) against LGI1. We explore their sequences and binding characteristics, plus their pathogenic potential using transfected HEK293T cells, rodent neuronal preparations, and behavioural and electrophysiological assessments in vivo after mAb injections into the rodent hippocampus. In live cell-based assays, LGI1 epitope recognition was examined with patient sera (n = 31), CSFs (n = 11), longitudinal serum samples (n = 15), and using mAbs (n = 14) generated from peripheral B cells of two patients. All sera and 9/11 CSFs bound both the leucine-rich repeat (LRR) and the epitempin repeat (EPTP) domains of LGI1, with stable ratios of LRR:EPTP antibody levels over time. By contrast, the mAbs derived from both patients recognized either the LRR or EPTP domain. mAbs against both domain specificities showed varied binding strengths, and marked genetic heterogeneity, with high mutation frequencies. LRR-specific mAbs recognized LGI1 docked to its interaction partners, ADAM22 and ADAM23, bound to rodent brain sections, and induced internalization of the LGI1-ADAM22/23 complex in both HEK293T cells and live hippocampal neurons. By contrast, few EPTP-specific mAbs bound to rodent brain sections or ADAM22/23-docked LGI1, but all inhibited the docking of LGI1 to ADAM22/23. After intrahippocampal injection, and by contrast to the LRR-directed mAbs, the EPTP-directed mAbs showed far less avid binding to brain tissue and were consistently detected in the serum. Post-injection, both domain-specific mAbs abrogated long-term potentiation induction, and LRR-directed antibodies with higher binding strengths induced memory impairment. Taken together, two largely dichotomous populations of LGI1 mAbs with distinct domain binding characteristics exist in the affinity matured peripheral autoantigen-specific memory pools of individuals, both of which have pathogenic potential. In human autoantibody-mediated diseases, the detailed characterization of patient mAbs provides a valuable method to dissect the molecular mechanisms within polyclonal populations.

Technical Nuances in Neuroendoscopic Lavage for Germinal Matrix Hemorrhage in Preterm Infants: Twenty Tips and Pearls after More than One Hundred Procedures.

INTRODUCTION: Posthemorrhagic hydrocephalus in preterm infants is a serious entity related to high mortality and morbidity. Neuroendoscopic lavage (NEL) is a suitable alternative for the management of this pathology. However, as with every endoscopic technique, it requires some experience and several cases to master. METHODS: We present a descriptive study of some technical nuances, tips, and tricks that have been learned in the last 8 years with over a hundred NELs performed in preterm infants. These variations are classified into 3 categories according to their temporal relationship with the surgical procedure: preoperative stage, intraoperative stage, and postoperative stage. We include a brief description of each one and the reasons why they are included in our current clinical practice. RESULTS: Twenty tips and pearls were described in detail and are reported here. Preoperative, intraoperative, and postoperative variations were exposed and related to the most frequent complications of this procedure: infection, cerebrospinal fluid leak, and rebleeding. CONCLUSIONS: NEL is a useful technique for the management of germinal matrix hemorrhage in preterm infants. These technical nuances have improved the results of our technique and helped us to prevent complications related to the procedure.

Positive staining of the immunoligand B7-H6 in abnormal/transformed keratinocytes consistently accompanies the progression of cervical cancer.

BACKGROUND: B7-H6 has been revealed as an endogenous immunoligand expressed in a variety of tumors, but not expressed in healthy tissues. Heretofore, no studies have been reported describing B7-H6 in women with cervical cancer. To investigate this question, our present study was conducted. RESULTS: This retrospective study comprised a total of 62 paraffinized cervical biopsies, which were distributed in five groups: low-grade squamous intraepithelial lesions (LSIL), high-grade squamous intraepithelial lesions (HSIL), squamous cervical carcinoma (SCC), uterine cervical adenocarcinoma (UCAC), and a group of cervicitis (as a control for non-abnormal/non-transformed cells). Cervical sections were stained by immunohistochemistry to explore the expression of B7-H6, which was reported according to the immunoreactive score (IRS) system. We observed a complete lack of B7-H6 in LSIL abnormal epithelial cells. Interestingly, B7-H6 began to be seen in HSIL abnormal epithelial cells; more than half of this group had B7-H6 positive cells, with staining characterized by a cytoplasmic and membranous pattern. B7-H6 in the SCC group was also seen in the majority of the sections, showing the same cytoplasmic and membranous pattern. Strong evidence of B7-H6 was notably found in UCAC tumor columnar cells (in 100% of the specimens, also with cytoplasmic and membranous pattern). Moreover, consistent B7-H6 staining was observed in infiltrating plasma cells in all groups. CONCLUSIONS: B7-H6 IRS positively correlated with disease stage in the development of cervical cancer; additionally, B7-H6 scores were found to be even higher in the more aggressive uterine cervical adenocarcinoma, suggesting a possible future therapeutic target for this cancer type.

B7-H6, an immunoligand for the natural killer cell activating receptor NKp30, reveals inhibitory effects on cell proliferation and migration, but not apoptosis, in cervical cancer derived-cell lines.

BACKGROUND: Although great progress has been made in treatment regimens, cervical cancer remains as one of the most common cancer in women worldwide. Studies focusing on molecules that regulate carcinogenesis may provide potential therapeutic strategies for cervical cancer. B7-H6, an activating immunoligand expressed by several tumor cells, is known to activate NK cell-mediated cytotoxicity once engaged with its natural receptor NKp30. However, the opposite, that is, the effects in the tumor cell triggered by B7-H6 after interacting with NKp30 has not yet been well explored. METHODS: In this study, we evaluated the surface expression of B7-H6 by flow cytometry. Later, we stimulated B7-H6 positive cervical cancer derived-cell lines (HeLa and SiHa) with recombinant soluble NKp30 (sNKp30) protein and evaluated biological effects using the impedance RTCA system for cell proliferation, the scratch method for cell migration, and flow cytometry for apoptosis. Cellular localization of B7-H6 was determined using confocal microscopy. RESULTS: Notably, we observed that the addition of sNKp30 to the cervical cancer cell lines decreased tumor cell proliferation and migration rate, but had no effect on apoptosis. We also found that B7-H6 is selectively maintained in tumor cell lines, and that efforts to sort and purify B7-H6 negative or positive cells were futile, as negative cells, when cultured, regained the expression of B7-H6 and B7-H6 positive cells, when sorted and cultivated, lost a percentage of B7-H6 expression. CONCLUSIONS: Our results suggest that B7-H6 has an important, as of yet undescribed, role in the biology of the cervical tumor cells themselves, suggesting that this protein might be a promising target for anti-tumor therapy in the future.

Effects of chronic immobilization stress on biokinetics and dosimetry of 67Ga in a murine model.

The aim of this work is to determine the effect of chronic immobilization stress on kinetics and dosimetry of 67Ga in a mouse model. A control group (CG) and a stress group (SG), each with 15 mice, were included in the study, and the latter group was subjected to a chronic immobilization stress model 2 h daily for 14 consecutive days. At day 13, 67Ga-citrate was administered intraperitoneally (11.24 ± 0.44 MBq) to each mouse. Then, sets of three mice were obtained sequentially at 24, 36, 48, 60 and 72 h, in which the radionuclide activity was measured with an activity counter. The 67Ga biokinetic data showed a fast blood clearance in the SG, with a mean residence time of 0.06 h. The calculated mean radiation absorbed doses were: liver (2.45 × 10-03 Gy), heart (3.17 × 10-04 Gy) and kidney (1.88 × 10-04 Gy) in the SG. The results show that stress reduced weight gain by approximately 13% and also increased adrenal gland weight by 26%. On the other hand, chronic stress accelerates 67Ga clearance after 24 h compared to normal conditions. It is concluded that murine organisms under chronic immobilization stress have higher gallium-67 clearance rates, decreasing the cumulated activity and absorbed dose in all organs.

Origins of Alterations to Rankl Null Mutant Mouse Dental Root Development.

The purpose of the present study was to assess the early stages of development of mouse first molar roots in the osteopetrotic context of RANKL invalidation in order to demonstrate that the radicular phenotype observed resulted not only from defective osteoclasts, but also from loss of cell-to-cell communication among dental, periodontium and alveolar bone cells involving RANKL signaling. Two experimental models were used in this study: Rankl mutants with permanent RANKL invalidation, and C57BL/6J mice injected during the first postnatal week with a RANKL neutralizing antibody corresponding to a transient RANKL invalidation. The dento-alveolar complex was systematically analyzed using micro-CT, and histological and immunohistochemical approaches. These experiments showed that the root elongation alterations observed in the Rankl-/- mice were associated with reduced proliferation of the RANK-expressing HERS cells with a significant decrease in proliferating cell nuclear antigen (PCNA) expression and a significant increase in P21 expression. The phenotypic comparison of the adult first molar root at 35 days between permanent and transitory invalidations of RANKL made it possible to demonstrate that alterations in dental root development have at least two origins, one intrinsic and linked to proliferation/differentiation perturbations in dental-root-forming cells, the other extrinsic and corresponding to disturbances of bone cell differentiation/function.

Melanopsin for precise optogenetic activation of astrocyte-neuron networks.

Optogenetics has been widely expanded to enhance or suppress neuronal activity and it has been recently applied to glial cells. Here, we have used a new approach based on selective expression of melanopsin, a G-protein-coupled photopigment, in astrocytes to trigger Ca2+ signaling. Using the genetically encoded Ca2+ indicator GCaMP6f and two-photon imaging, we show that melanopsin is both competent to stimulate robust IP3-dependent Ca2+ signals in astrocyte fine processes, and to evoke an ATP/Adenosine-dependent transient boost of hippocampal excitatory synaptic transmission. Additionally, under low-frequency light stimulation conditions, melanopsin-transfected astrocytes can trigger long-term synaptic changes. In vivo, melanopsin-astrocyte activation enhances episodic-like memory, suggesting melanopsin as an optical tool that could recapitulate the wide range of regulatory actions of astrocytes on neuronal networks in behaving animals. These results describe a novel approach using melanopsin as a precise trigger for astrocytes that mimics their endogenous G-protein signaling pathways, and present melanopsin as a valuable optical tool for neuron-glia studies.