Search results
Found 4802 matches for
Higher-order thalamocortical circuits are specified by embryonic cortical progenitor types in the mouse brain.
The sensory cortex receives synaptic inputs from both first-order and higher-order thalamic nuclei. First-order inputs relay simple stimulus properties from the periphery, whereas higher-order inputs relay more complex response properties, provide contextual feedback, and modulate plasticity. Here, we reveal that a cortical neuron's higher-order input is determined by the type of progenitor from which it is derived during embryonic development. Within layer 4 (L4) of the mouse primary somatosensory cortex, neurons derived from intermediate progenitors receive stronger higher-order thalamic input and exhibit greater higher-order sensory responses. These effects result from differences in dendritic morphology and levels of the transcription factor Lhx2, which are specified by the L4 neuron's progenitor type. When this mechanism is disrupted, cortical circuits exhibit altered higher-order responses and sensory-evoked plasticity. Therefore, by following distinct trajectories, progenitor types generate diversity in thalamocortical circuitry and may provide a general mechanism for differentially routing information through the cortex.
A multinational report on SARS-COV-2 infection outcomes in people with CF and Aspergillus infection or ABPA.
BACKGROUND: Aspergillus infection is known to be associated with worse respiratory outcomes in people with CF (pwCF) and is a well-recognised complication of severe SARS-CoV-2 infection. The aim of this observational cross-sectional study was to examine the association of pre-existing Aspergillus infection and/or allergic bronchopulmonary aspergillosis (ABPA) in pwCF and severity of COVID-19. METHODS: Data on SARS-CoV-2 infections in pwCF from January 2020 to June 2021 were collected by the European Cystic Fibrosis Society Patient Registry. The primary outcome was COVID-19 severity measured by hospitalisation comparing those with Aspergillus infection and/or ABPA in the 12 months preceding COVID-19and those without. RESULTS: In total, 1095 pwCF were diagnosed with SARS-CoV-2 and information on pre-existing Aspergillus/ABPA status was available from 807. PwCF and SARS-CoV-2 in the Aspergillus/ABPA group (n = 153), in comparison to the non-Aspergillus/ABPA group (n = 654), were more likely to be hospitalised (adjusted OR 1.79 (1.19 to 2.85); p = 0.005) and their disease course was more likely to be complicated by sepsis (adjusted OR 7.78 (1.78 to 49.43); p = 0.008). The association with hospital admission was no longer significant after excluding patients with ABPA. Secondary analysis comparing pwCF who received antifungal treatment (n = 18), versus those who did not (n = 474) during COVID-19, showed a higher rate of hospitalisation (p
Correction: Modified minimal-size fragments of heparan sulfate as inhibitors of endosulfatase-2 (Sulf-2).
Correction for 'Modified minimal-size fragments of heparan sulfate as inhibitors of endosulfatase-2 (Sulf-2)' by Alice Kennett et al., Chem. Commun., 2024, 60, 436-439, https://doi.org/10.1039/D3CC02565A.
Rebound activation of 5-HT neurons following SSRI discontinuation.
Cessation of therapy with a selective serotonin (5-HT) reuptake inhibitor (SSRI) is often associated with an early onset and disabling discontinuation syndrome, the mechanism of which is surprisingly little investigated. Here we determined the effect on 5-HT neurochemistry of discontinuation from the SSRI paroxetine. Paroxetine was administered repeatedly to mice (once daily, 12 days versus saline controls) and then either continued or discontinued for up to 5 days. Whereas brain tissue levels of 5-HT and/or its metabolite 5-HIAA tended to decrease during continuous paroxetine, levels increased above controls after discontinuation, notably in hippocampus. In microdialysis experiments continuous paroxetine elevated hippocampal extracellular 5-HT and this effect fell to saline control levels on discontinuation. However, depolarisation (high potassium)-evoked 5-HT release was reduced by continuous paroxetine but increased above controls post-discontinuation. Extracellular hippocampal 5-HIAA also decreased during continuous paroxetine and increased above controls post-discontinuation. Next, immunohistochemistry experiments found that paroxetine discontinuation increased c-Fos expression in midbrain 5-HT (TPH2 positive) neurons, adding further evidence for a hyperexcitable 5-HT system. The latter effect was recapitulated by 5-HT1A receptor antagonist administration although gene expression analysis could not confirm altered expression of 5-HT1A autoreceptors following paroxetine discontinuation. Finally, in behavioural experiments paroxetine discontinuation increased anxiety-like behaviour, which partially correlated in time with the measures of increased 5-HT function. In summary, this study reports evidence that, across a range of experiments, SSRI discontinuation triggers a rebound activation of 5-HT neurons. This effect is reminiscent of neural changes associated with various psychotropic drug withdrawal states, suggesting a common unifying mechanism.
Comparative and integrated analysis of plasma extracellular vesicle isolation methods in healthy volunteers and patients following myocardial infarction
AbstractPlasma extracellular vesicle (EV) number and composition are altered following myocardial infarction (MI), but to properly understand the significance of these changes it is essential to appreciate how the different isolation methods affect EV characteristics, proteome and sphingolipidome. Here, we compared plasma EV isolated from platelet‐poor plasma from four healthy donors and six MI patients at presentation and 1‐month post‐MI using ultracentrifugation (UC), polyethylene glycol precipitation, acoustic trapping, size‐exclusion chromatography (SEC) and immunoaffinity capture. The isolated EV were evaluated by Nanoparticle Tracking Analysis (NTA), Western blot, transmission electron microscopy (TEM), an EV‐protein array, untargeted proteomics (LC‐MS/MS) and targeted sphingolipidomics (LC‐MS/MS). The application of the five different plasma EV isolation methods in patients presenting with MI showed that the choice of plasma EV isolation method influenced the ability to distinguish elevations in plasma EV concentration following MI, enrichment of EV‐cargo (EV‐proteins and sphingolipidomics) and associations with the size of the infarct determined by cardiac magnetic resonance imaging 6 months post‐MI. Despite the selection bias imposed by each method, a core of EV‐associated proteins and lipids was detectable using all approaches. However, this study highlights how each isolation method comes with its own idiosyncrasies and makes the comparison of data acquired by different techniques in clinical studies problematic.
The TMEM16A channel as a potential therapeutic target in vascular disease.
PURPOSE OF REVIEW: The transmembrane protein 16A (TMEM16A) Ca 2+ -activated Cl - channel constitutes a key depolarising mechanism in vascular smooth muscle and contractile pericytes, while in endothelial cells the channel is implicated in angiogenesis and in the response to vasoactive stimuli. Here, we offer a critical analysis of recent physiological investigations and consider the potential for targeting TMEM16A channels in vascular disease. RECENT FINDINGS: Genetic deletion or pharmacological inhibition of TMEM16A channels in vascular smooth muscle decreases artery tone and lowers systemic blood pressure in rodent models. Inhibition of TMEM16A channels in cerebral cortical pericytes protects against ischemia-induced tissue damage and improves microvascular blood flow in rodent stroke models. In endothelial cells, the TMEM16A channel plays varied roles including modulation of cell division and control of vessel tone through spread of hyperpolarisation to the smooth muscle cells. Genetic studies implicate TMEM16A channels in human disease including systemic and pulmonary hypertension, stroke and Moyamoya disease. SUMMARY: The TMEM16A channel regulates vascular function by controlling artery tone and capillary diameter as well as vessel formation and histology. Preclinical and clinical investigations are highlighting the potential for therapeutic exploitation of the channel in a range of maladaptive states of the (micro)circulation.
Evidence for a Role of 5-HT-glutamate Co-releasing Neurons in Acute Stress Mechanisms.
A major subpopulation of midbrain 5-hydroxytryptamine (5-HT) neurons expresses the vesicular glutamate transporter 3 (VGLUT3) and co-releases 5-HT and glutamate, but the function of this co-release is unclear. Given the strong links between 5-HT and uncontrollable stress, we used a combination of c-Fos immunohistochemistry and conditional gene knockout mice to test the hypothesis that glutamate co-releasing 5-HT neurons are activated by stress and involved in stress coping. Acute, uncontrollable swim stress increased c-Fos immunoreactivity in neurons co-expressing VGLUT3 and the 5-HT marker tryptophan hydroxylase 2 (TPH2) in the dorsal raphe nucleus (DRN). This effect was localized in the ventral DRN subregion and prevented by the antidepressant fluoxetine. In contrast, a more controllable stressor, acute social defeat, had no effect on c-Fos immunoreactivity in VGLUT3-TPH2 co-expressing neurons in the DRN. To test whether activation of glutamate co-releasing 5-HT neurons was causally linked to stress coping, mice with a specific deletion of VGLUT3 in 5-HT neurons were exposed to acute swim stress. Compared to wildtype controls, the mutant mice showed increased climbing behavior, a measure of active coping. Wildtype mice also showed increased climbing when administered fluoxetine, revealing an interesting parallel between the behavioral effects of genetic loss of VGLUT3 in 5-HT neurons and 5-HT reuptake inhibition. We conclude that 5-HT-glutamate co-releasing neurons are recruited by exposure to uncontrollable stress. Furthermore, natural variation in the balance of 5-HT and glutamate co-released at the 5-HT synapse may impact stress susceptibility.
A novel, patient-derived RyR1 mutation impairs muscle function and calcium homeostasis in mice.
RYR1 is the most commonly mutated gene associated with congenital myopathies, a group of early-onset neuromuscular conditions of variable severity. The functional effects of a number of dominant RYR1 mutations have been established; however, for recessive mutations, these effects may depend on multiple factors, such as the formation of a hypomorphic allele, or on whether they are homozygous or compound heterozygous. Here, we functionally characterize a new transgenic mouse model knocked-in for mutations identified in a severely affected child born preterm and presenting limited limb movement. The child carried the homozygous c.14928C>G RYR1 mutation, resulting in the p.F4976L substitution. In vivo and ex vivo assays revealed that homozygous mice fatigued sooner and their muscles generated significantly less force compared with their WT or heterozygous littermates. Electron microscopy, biochemical, and physiological analyses showed that muscles from RyR1 p.F4976L homozygous mice have the following properties: (1) contain fewer calcium release units and show areas of myofibrillar degeneration, (2) contain less RyR1 protein, (3) fibers show smaller electrically evoked calcium transients, and (4) their SR has smaller calcium stores. In addition, single-channel recordings indicate that RyR1 p.F4976L exhibits higher Po in the presence of 100 μM [Ca2+]. Our mouse model partly recapitulates the clinical picture of the homozygous human patient and provides significant insight into the functional impact of this mutation. These results will help understand the pathology of patients with similar RYR1 mutations.