Abstract Neurogenesis in the adult dentate gyrus (DG) of the hippocampus has been implicated in neural plasticity and cognition but the specific functions contributed by adult-born neurons remain ...controversial. Here, we have explored the relationship between adult hippocampal neurogenesis and memory function using tasks which specifically require the participation of the DG. In two separate experiments several groups of rats were exposed to fractionated ionizing radiation (two sessions of 7 Gy each on consecutive days) applied either to the whole brain or focally, aiming at a region overlying the hippocampus. The immunocytochemical assays showed that the radiation significantly reduced the expression of doublecortin (DCX), a marker for immature neurons, in the dorsal DG. Ultrastructural examination of the DG region revealed disruption of progenitor cell niches several weeks after the radiation. In the first experiment, whole-brain and focal irradiation reduced DCX expression by 68% and 43%, respectively. Whole-brain and focally-irradiated rats were unimpaired compared with control rats in a matching-to-place (MTP) working memory task performed in the T-maze and in the long-term retention of the no-alternation rule. In the second experiment, focal irradiation reduced DCX expression by 36% but did not impair performance on (1) a standard non-matching-to-place (NMTP) task, (2) a more demanding NMTP task with increasingly longer within-trial delays, (3) a long-term retention test of the alternation rule and (4) a spatial reversal task. However, rats irradiated focally showed clear deficits in a “purely” contextual fear-conditioning task at short and long retention intervals. These data demonstrate that reduced adult hippocampal neurogenesis produces marked deficits in the rapid acquisition of emotionally relevant contextual information but spares spatial working memory function, the long-term retention of acquired spatial rules and the ability to flexibly modify learned spatial strategies.
The hippocampus is believed to play a role in processing information relative to the context in which emotionally salient experiences occur but evidence on the specific contribution of the ...hippocampal dentate gyrus (DG) to these processes is limited. Here, we have used two classical behavioral paradigms to study the participation of the dorsal DG in context-conditioned reward and context-conditioned fear. Rats received intra-hippocampal vehicle or colchicine injections (4
μg/μl solution; 0.2
μl injections at 10 sites) that damaged the DG but spared other hippocampal subfields. In the first experiment, we used a place conditioning procedure pairing cocaine exposure (20
mg/kg, i.p.) with a specific context and vehicle treatment with another. While rats with sham lesions exhibited preference for the cocaine-paired context following conditioning, rats with lesions of the DG showed no evidence of cocaine-induced place preference. In the second experiment, rats with sham or colchicine lesions received a foot shock in a given context and conditioned freezing was measured upon reexposure to the shock-paired context (2, 24, 48 and 96
h after conditioning). Rats with sham lesions exhibited high levels of conditioned freezing when exposed to the conditioning context but rats with lesions of the DG showed impaired conditioning, behaving as controls that had experienced shock in a different context. These observations indicate that the integrity of the DG is essential for establishing a coherent representation of the context to which emotional experiences, either hedonic or aversive, are bound.
Cyanogen (NCCN) is the simplest member of the series of dicyanopolyynes. It has been hypothesized that this family of molecules can be important constituents of interstellar and circumstellar media, ...although the lack of a permanent electric dipole moment prevents its detection through radioastronomical techniques. Here we present the first solid evidence of the presence of cyanogen in interstellar clouds by detection of its protonated form toward the cold dark clouds TMC-1 and L483. Protonated cyanogen (NCCNH+) has been identified through the J = 5−4 and J = 10−9 rotational transitions using the 40 m radiotelescope of Yebes and the IRAM 30 m telescope. We derive beam-averaged column densities for NCCNH+ of (8.6 ± 4.4) × 1010 cm-2 in TMC-1 and (3.9 ± 1.8) × 1010 cm-2 in L483, which translate into fairly low fractional abundances relative to H2, in the range (1–10) × 10-12. The chemistry of protonated molecules in dark clouds is discussed, and it is found that, in general terms, the abundance ratio between the protonated and non-protonated forms of a molecule increases with increasing proton affinity. Our chemical model predicts an abundance ratio NCCNH+/NCCN of ~10-4, which implies that the abundance of cyanogen in dark clouds could be as high as (1–10) × 10-8 relative to H2, i.e., comparable to that of other abundant nitriles such as HCN, HNC, and HC3N.
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Cell transplantation therapies in the nervous system are frequently hampered by glial scarring and cell drain from the damaged site, among others. To improve this situation, new ...biomaterials may be of help. Here, novel single-channel tubular conduits based on hyaluronic acid (HA) with and without poly-l-lactide acid fibers in their lumen were fabricated. Rat Schwann cells were seeded within the conduits and cultured for 10days. The conduits possessed a three-layered porous structure that impeded the leakage of the cells seeded in their interior and made them impervious to cell invasion from the exterior, while allowing free transport of nutrients and other molecules needed for cell survival. The channel’s surface acted as a template for the formation of a cylindrical sheath-like tapestry of Schwann cells continuously spanning the whole length of the lumen. Schwann-cell tubes having a diameter of around 0.5mm and variable lengths can thus be generated. This structure is not found in nature and represents a truly engineered tissue, the outcome of the specific cell–material interactions. The conduits might be useful to sustain and protect cells for transplantation, and the biohybrids here described, together with neuronal precursors, might be of help in building bridges across significant distances in the central and peripheral nervous system.
The paper entitled “Schwann-cell cylinders grown inside hyaluronic-acid tubular scaffolds with gradient porosity” reports on the development of a novel tubular scaffold and on how this scaffold acts on Schwann cells seeded in its interior as a template to produce macroscopic hollow continuous cylinders of tightly joined Schwann cells. This cellular structure is not found in nature and represents a truly engineered novel tissue, which obtains as a consequence of the specific cell-material interactions within the scaffold.
Multifocal glioblastomas (ie, glioblastomas with multiple foci, unconnected in postcontrast pretreatment T1-weighted images) represent a challenge in clinical practice due to their poor prognosis. We ...wished to obtain imaging biomarkers with prognostic value that have not been found previously.
A retrospective review of 1155 patients with glioblastomas from 10 local institutions during 2006-2017 provided 97 patients satisfying the inclusion criteria of the study and classified as having multifocal glioblastomas. Tumors were segmented and morphologic features were computed using different methodologies: 1) measured on the largest focus, 2) aggregating the different foci as a whole, and 3) recording the extreme value obtained for each focus. Kaplan-Meier, Cox proportional hazards, correlations, and Harrell concordance indices (c-indices) were used for the statistical analysis.
Age (
< .001, hazard ratio = 2.11, c-index = 0.705), surgery (
< .001, hazard ratio = 2.04, c-index = 0.712), contrast-enhancing rim width (
< .001, hazard ratio = 2.15, c-index = 0.704), and surface regularity (
= .021, hazard ratio = 1.66, c-index = 0.639) measured on the largest focus were significant independent predictors of survival. Maximum contrast-enhancing rim width (
= .002, hazard ratio = 2.05, c-index = 0.668) and minimal surface regularity (
= .036, hazard ratio = 1.64, c-index = 0.600) were also significant. A multivariate model using age, surgery, and contrast-enhancing rim width measured on the largest foci classified multifocal glioblastomas into groups with different outcomes (
< .001, hazard ratio = 3.00, c-index = 0.853, median survival difference = 10.55 months). Moreover, quartiles with the highest and lowest individual prognostic scores based on the focus with the largest volume and surgery were identified as extreme groups in terms of survival (
< .001, hazard ratio = 18.67, c-index = 0.967).
A prognostic model incorporating imaging findings on pretreatment postcontrast T1-weighted MRI classified patients with glioblastoma into different prognostic groups.
Following the resection of newly diagnosed or recurrent glioblastomas, local implantation of carmustine-impregnated biodegradable wafers (Gliadel) in the resection cavity constitutes an adjuvant ...therapy that can improve the possibilities of survival. However, some precautions should be taken regarding Gliadel implantation. We report three cases in whom patients with glioblastoma multiforme were implanted with fibrin glue-secured Gliadel after the lateral ventricles had been opened, and who later developed severe hydrocephalus leading to death. Although Gliadel may be an important adjunct to treatment, opening of the ventricles during surgery as part of its application should be considered a contra-indication.
The kinetics of iron electrodeposition from acid sulphate solutions onto a platinum electrode was investigated by means of stationary polarisation curves and electrochemical impedance spectroscopy. ...Together with interfacial pH data previously obtained, the effect of pH was analysed. The formation of at least three adsorbed intermediates at the cathode surface was evidenced in all pH values. The relative rate of their formation and its surface concentration depend on the solution pH as well as on the electrode potential. It is suggested that two of these species catalyses the H
+ reduction whereas the other one may have a blocking effect on this reaction.
Background and objective
Occluding a ruptured intracranial aneurysm as early as possible may entail certain periprocedural conditions that compromise the outcome. The aim of the present study was to ...evaluate the effectiveness, safety, and clinical outcome of endovascular coiling procedures performed on an emergency basis under potentially suboptimal conditions, and to compare results with those from scheduled procedures under potentially optimal conditions.
Methods
Interventions performed on 66 SAH patients were retrospectively analysed by classifying them into two groups: under emergency (within three hours from diagnosis or during non–standard working hours) or scheduled conditions. A binary logistic regression analysis was also performed to identify characteristics associated with poor outcomes.
Results
No differences in effectiveness, periprocedural complications, or clinical outcomes were found between the two groups. Rebleeding was detected in 4.8 % of the emergency interventions and 2.2 % of the scheduled interventions. Multivariate analysis identified age and Hunt and Hess grade, but no conditions of treatment, as the factors associated to poor outcome.
Conclusion
Suboptimal interventional conditions for occluding ruptured intracranial aneurysms, such as performing procedures outside of standard working hours or within three hours of diagnosis, do not result in increased periprocedural complications and poor clinical outcomes compared with scheduled procedures under potentially optimal conditions. These results suggest the need for treatment to be provided as soon as possible.
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