Stroke is a devastating disease with an increasing prevalence. Part of the current development in stroke therapy is focused in the chronic phase, where neurorepair mechanisms such as neurogenesis, ...are involved. In the adult brain, one of the regions where neurogenesis takes place is the subventricular zone (SVZ) of the lateral ventricles. Given the possibility to develop pharmacological therapies to stimulate this process, we have performed a longitudinal analysis of neurogenesis in a model of cortical ischemia in mice. Our results show an initial decrease of SVZ proliferation at 24 h, followed by a recovery leading to an increase at 14d and a second decrease 28d after stroke. Coinciding with the 24 h proliferation decrease, an increase in the eutopic neuroblast migration towards the olfactory bulb was observed. The analysis of the neuroblast ectopic migration from the SVZ toward the lesion showed an increase in this process from day 14 after the insult. Finally, our data revealed an increased number of new cortical neurons in the peri-infarct cortex 65d after the insult. In summary, we report here critical check-points about post-stroke neurogenesis after cortical infarcts, important for the pharmacological modulation of this process in stroke patients.
•Immunocompromised patients are at increased risk for severe COVID-19.•Host-targeting antivirals offer a promising therapy in SARS-CoV-2 infection.•The emergence of new SARS-CoV-2 variants raises the ...need to develop new antivirals.•Plitidepsin may contribute to SARS-CoV-2 clearance in immunocompromised patients.
To evaluate the compassionate use of plitidepsin as an antiviral treatment in hospitalized immunocompromised adult patients with moderate-to-severe COVID-19.
Retrospective observational study of data —collected from January 01, 2021 to April 30, 2022— from 35 immunocompromised adult patients with COVID-19 non-eligible for other available antiviral treatments. Main outcome measures were time to respiratory recovery (SpFi ≥ 315); COVID-19-related 30-day-cumulative mortality after first plitidepsin infusion; and time to undetectable levels of viral RNA.
Thirty-three patients receiving a full course of plitidepsin (2.5 mg n = 29 or 1.5 mg n = 4) were included. Most (69.7%) had a malignant hematologic disease and 27.3% had solid tumors. A total of 111 infusions were administered with lack of relevant safety events. Median time from plitidepsin initiation to SpFi ≥315 was 8 days (95% confidence interval CI, 7-19). Median time to first negative reverse transcription-polymerase chain reaction for SARS-CoV-2 (cycle threshold >36) was 17 days (95% CI 13-25). Mortality rate was 16.3% (95% CI 3-37.3).
These data support plitidepsin as a well-tolerated treatment that might have potential clinical and antiviral efficacy in COVID-19 immunocompromised patients.
Abstract Chronic impairment of forelimb and digit movement is a common problem after stroke that is resistant to therapy. Although in the last years some studies have been performed to increase the ...efficacy of rehabilitative experience and training, the pharmacological approaches in this context remain poorly developed. We decided to study the effect of a chronic treatment with CDP-choline, a safe and well-tolerated drug that is known to stabilize membranes, on functional outcome and neuromorphological changes after stroke. To assess the functional recovery we have performed the staircase reaching test and the elevated body swing test (EBST), for studying sensorimotor integration and asymmetrical motor function respectively. The treatment with CDP-choline, initiated 24 h after the middle cerebral artery occlusion (MCAO) and maintained during 28 days, improved the functional outcome in both the staircase test (MCAO + CDP = 87.0 ± 6.6% pellets eaten vs. MCAO + SAL = 40.0 ± 4.5%; p < 0.05) and the EBST (MCAO + CDP = 70.0 ± 6.8% vs. MCAO + SAL = 88.0 ± 5.4%; contralateral swing p < 0.05). In addition, to study potential neuronal substrates of the improved function, we examined the dendritic morphology of layer V pyramidal cells in the undamaged motor cortex using a Golgi–Cox procedure. The animals treated with CDP-choline showed enhanced dendritic complexity and spine density compared with saline group. Our results suggest that a chronic treatment with CDP-choline initiated 24 h after the insult is able to increase the neuronal plasticity within noninjured and functionally connected brain regions as well as to promote functional recovery.
► Our results show that daidzein has PPARγ-dependent beneficial actions. ► Daidzein compound did not show ability for direct binding to the receptor. ► Daidzein produces modifications of PPARγ ...localization.
Phytoestrogens are a group of plant-derived compounds that include mainly isoflavones like daidzein. Phytoestrogens prevent neuronal damage and improve outcome in experimental stroke; however, the mechanisms of this neuroprotective action have not been fully elucidated. In this context, it has been postulated that phytoestrogens might activate the peroxisome proliferator-activated receptor-γ (PPARγ), which exerts neuroprotective effects in several settings. The aim of this study was to determine whether the phytoestrogen daidzein elicits beneficial actions in neuronal cells by mechanisms involving activation of PPARγ. Our results show that daidzein (0.05–5μM) decreases cell death induced by exposure to oxygen–glucose deprivation (OGD) from rat cortical neurons and that improves synaptic function, in terms of increased synaptic vesicle recycling at nerve terminals, being both effects inhibited by the PPARγ antagonist T0070907 (1μM). In addition, this phytoestrogen activated PPARγ in neuronal cultures, as shown by an increase in PPARγ transcriptional activity. Interestingly, these effects were not due to binding to the receptor ligand site, as shown by a TR-FRET PPARγ competitive binding assay. Conversely, daidzein increased PPARγ nuclear protein levels and decreased cytosolic ones, suggesting nuclear translocation. We have used the receptor antagonist (RE) fulvestrant to study the neuroprotective participation of daidzein via estrogen receptor and at least in our model, we have discarded this pathway. These results demonstrate that the phytoestrogen daidzein has cytoprotective properties in neurons, which are due to an increase in PPARγ activity not mediated by direct binding to the receptor ligand-binding domain but likely due to post-translational modifications affecting its subcellular location and not depending to the RE and it is not additive with the agonist rosiglitazone.
Abstract Glutamate transport is the only mechanism for maintaining extracellular glutamate concentrations below excitotoxic levels. Among glutamate transporters, EAAT2 is responsible for up to 90% of ...all glutamate transport and has been reported to be associated to lipid rafts. In this context, we have recently shown that CDP-choline induces EAAT2 translocation to the membrane. Since CDP-choline preserves membrane stability by recovering levels of sphingomyelin, a glycosphingolipid present in lipid rafts, we have decided to investigate whether CDP-choline increases association of EAAT2 transporter to lipid rafts. Flotillin-1 was used as a marker of lipid rafts due to its known association to these microdomains. After gradient centrifugation, we have found that flotillin-1 appears mainly in fractions 2 and 3 and that EAAT2 protein is predominantly found colocalised with flotillin-1 in fraction 2. We have also demonstrated that CDP-choline increased EAAT2 levels in fraction 2 at both times examined (3 and 6 h after 1 g/kg CDP-choline administration). In agreement with this, 3 H glutamate uptake was also increased in flotillin-associated vesicles obtained from brain homogenates of animals treated with CDP-choline. Exposure to middle cerebral artery occlusion also increased EAAT2 levels in lipid rafts, an effect which was further enhanced in those animals receiving 2 g/kg CDP-choline 4 h after the occlusion. Infarct volume measured at 48 h after ischemia showed a reduction in the group treated with CDP-choline 4 h after occlusion. In summary, we have demonstrated that CDP-choline redistributes EAAT2 to lipid raft microdomains and improves glutamate uptake. This effect is also found after experimental stroke, when CDP-choline is administered 4 h after the ischemic occlusion. Since we have also shown that this delayed post-ischemic administration of CDP-choline induces a potent neuroprotection, our data provides a novel target for neuroprotection in stroke.
A short ischemic event (ischemic preconditioning) can result in subsequent resistance to severe ischemic injury (ischemic tolerance). Glutamate is released after ischemia and produces cell death. It ...has been described that after ischemic preconditioning, the release of glutamate is reduced. We have shown that an in vitro model of ischemic preconditioning produces upregulation of glutamate transporters which mediates brain tolerance. We have now decided to investigate whether ischemic preconditioning-induced glutamate transporter upregulation takes also place in vivo, its cellular localization and the mechanisms by which this upregulation is controlled. A period of 10 min of temporary middle cerebral artery occlusion was used as a model of ischemic preconditioning in rat. EAAT1, EAAT2 and EAAT3 glutamate transporters were found in brain from control animals. Ischemic preconditioning produced an up-regulation of EAAT2 and EAAT3 but not of EAAT1 expression. Ischemic preconditioning-induced increase in EAAT3 expression was reduced by the TNF-α converting enzyme inhibitor BB1101. Intracerebral administration of either anti-TNF-α antibody or of a TNFR1 antisense oligodeoxynucleotide also inhibited ischemic preconditioning-induced EAAT3 up-regulation. Immunohistochemical studies suggest that, whereas the expression of EAAT3 is located in both neuronal cytoplasm and plasma membrane, ischemic preconditioning-induced up-regulation of EAAT3 is mainly localized at the plasma membrane level. In summary, these results demonstrate that in vivo ischemic preconditioning increases the expression of EAAT2 and EAAT3 glutamate transporters the upregulation of the latter being at least partly mediated by TNF-α converting enzyme/TNF-α/TNFR1 pathway.
Cerebrovascular disease is one of the leading causes of death, disability and dementia around the world. For the most common form of the disease, ischaemic stroke, there is only one drug available, ...tissue plasminogen activator, and few patients can benefit from this therapy because of the strict inclusion criteria established for its use. This circumstance makes it crucial to search for new forms of treatment to combat the sequelae of the disease, and this requires the development of new biomimetic models that allow for a better understanding of its evolution.
In this review, we update the platforms and models most widely used in recent years to study the pathophysiology of ischaemic stroke. On the one hand, we review the two- and three-dimensional platforms on which in vitro assays are carried out and, on the other, we describe the most commonly used in vivo experimental models and techniques for assessing ischaemic damage.
The ultimate aim of developing good experimental models is to find new forms of treatment and thus improve patients' prognosis and quality of life. It is therefore important to generate new in vitro devices and to further refine in vivo models to enable a good clinical translation.
A short ischemic event (ischemic preconditioning (IPC)) can result in subsequent resistance to severe ischemic injury (ischemic tolerance (IT)). The expression and neuroprotective role of tumor ...necrosis factor (TNF-α) have been described in models of IPC and we have showed the participation of its processing enzyme, the TNF-α convertase enzyme (TACE) in this process. We have now decided to explore the expression and localization of TNF receptors (TNFR) as well as other signalling mechanisms involved in IT. A period of 10 mins of temporary middle cerebral artery occlusion (tMCAO) was used for focal IPC. To evaluate the ability of IPC to produce IT, permanent MCAO was performed 48 hours after IPC. Ischemic preconditioning produced a reduction in infarct volume, as we showed previously. Ischemic preconditioning caused upregulation of neuronal TNFR1 that was reduced by the selective TACE inhibitor BB1101. Intracerebral administration of TNFR1 antisense oligodeoxynucleotide, which caused a reduction in TNFR1 expression, inhibited the IPC-induced protective effect, showing that TNFR1 upregulation is implicated in IT. Moreover, treatment with BB1101, TNFR1 antisense and lactacystin—a specific proteasome inhibitor—blocked IPC-induced NF-κB. Immunohistochemical studies showed the expression of TACE and TNFR1 in neurons. In summary, these data show that IPC produces neuronal upregulation of TACE and TNFR1, and that the pathway TACE/TNF-α/TNFR1/NF-κB is involved in IT.
FANCM Limits Meiotic Crossovers Crismani, Wayne; Girard, Chloé; Froger, Nicole ...
Science (American Association for the Advancement of Science),
06/2012, Letnik:
336, Številka:
6088
Journal Article
Recenzirano
The number of meiotic crossovers (COs) is tightly regulated within a narrow range, despite a large excess of molecular precursors. The factors that limit COs remain largely unknown. Here, using a ...genetic screen in Arabidopsis thaliana, we identified the highly conserved FANCM helicase, which is required for genome stability in humans and yeasts, as a major factor limiting meiotic CO formation. The fancm mutant has a threefold-increased CO frequency as compared to the wild type. These extra COs arise not from the pathway that accounts for most of the COs in wild type, but from an alternate, normally minor pathway. Thus, FANCM is a key factor imposing an upper limit on the number of meiotic COs, and its manipulation holds much promise for plant breeding.
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