Calcium channel blockade with nimodipine reverses MRI evidence of cerebral oedema following acute hypoxia

Dissolving microneedles loaded with nimodipine for prevention of sleep disorders at a high altitude

Sleep disorders are one of the most common acute reactions on the plateau, which can cause serious complications. However, there is no effective and safe treatment currently available. Nimodipine (NMD) is a dihydropyridine calcium channel blocker with neuroprotective and vasodilating activity, mainly used for the treatment of ischemic brain injury. Commercial oral or injectable NMD formulations are not a good option for central neuron diseases due to their poor brain delivery. In this study, nimodipine dissolving microneedles (NDMNs) were prepared for the prevention of sleep disorders caused by hypoxia. NDMNs were composed of NMD and polyvinyl pyrrolidone (PVP) K90 with a conical morphology and high rigidity. After administration of NDMNs on the back neck of mice, the concentration of NMD in the brain was significantly higher than that of oral medication as was confirmed by the fluorescent imaging on mouse models. NDMNs enhanced cognitive function, alleviated oxidative stress, and improved the sleep quality of mice with high-altitude sleep disorders. The blockage of calcium ion overloading may be an important modulation mechanism. NDMNs are a promising and user-friendly formulation for the prevention of high-altitude sleep disorders.

Sirtuins as Potential Targets for Neuroprotection: Mechanisms of Early Brain Injury Induced by Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a prevalent cerebrovascular disease with significant global mortality and morbidity rates. Despite advancements in pharmacological and surgical approaches, the quality of life for SAH survivors has not shown substantial improvement. Traditionally, vasospasm has been considered a primary contributor to death and disability following SAH, but anti-vasospastic therapies have not demonstrated significant benefits for SAH patients' prognosis. Emerging studies suggest that early brain injury (EBI) may play a crucial role in influencing SAH prognosis. Sirtuins (SIRTs), a group of NAD + -dependent deacylases comprising seven mammalian family members (SIRT1 to SIRT7), have been found to be involved in neural tissue development, plasticity, and aging. They also exhibit vital functions in various central nervous system (CNS) processes, including cognition, pain perception, mood, behavior, sleep, and circadian rhythms. Extensive research has uncovered the multifaceted roles of SIRTs in CNS disorders, offering insights into potential markers for pathological processes and promising therapeutic targets (such as SIRT1 activators and SIRT2 inhibitors). In this article, we provide an overview of recent research progress on the application of SIRTs in subarachnoid hemorrhage and explore their underlying mechanisms of action.

Protective Effect of Neferine in Permanent Cerebral Ischemic Rats via Anti-Oxidative and Anti-Apoptotic Mechanisms

Permanent cerebral ischemia is a consequence of prolonged cerebral artery occlusion that results in severe brain damage. Neurotoxicity occurring after ischemia can induce brain tissue damage by destroying cell organelles and their function. Neferine is a natural compound isolated from the seed embryos of the lotus plant and has broad pharmacological effects, including blockading of the calcium channels, anti-oxidative stress, and anti-apoptosis. This study investigated the ability of neferine to reduce brain injury after permanent cerebral occlusion. Permanent cerebral ischemia in rats was induced by instigation of occlusion of the middle cerebral artery for 24 h. The rats were divided into 6 groups: sham, permanent middle cerebral artery occlusion (pMCAO), pMCAO with neferine and nimodipine treatment. To investigate the severity of the injury, the neurological deficit score and morphological alterations were investigated. After 24 h, the rats were evaluated to assess neurological deficit, infarct volume, morphological change, and the number of apoptotic cell deaths. In addition, the brain tissues were examined by western blot analysis to calculate the expression of proteins related to oxidative stress and apoptosis. The data showed that the neurological deficit scores and the infarct volume were significantly reduced in the neferine-treated rats compared to the vehicle group. Treatment with neferine significantly reduced oxidative stress with a measurable decrease in 4-hydroxynonenal (4-HNE), nitric oxide (NO), neuronal nitric oxide (nNOS), and calcium levels and an upregulation of Hsp70 expression. Neferine treatment also significantly decreased apoptosis, with a decrease in Bax and cleaved caspase-3 and an increase in Bcl-2. This study suggested that neferine had a neuroprotective effect on permanent cerebral ischemia in rats by diminishing oxidative stress and apoptosis.

Oxygen Sensor of the Heart

How oxygen is sensed by the heart and what mechanisms mediate its sensing remain poorly understood. Since recent reports show that low PO₂ levels are detected by the cardiomyocytes in a few seconds, the rapid and short applications of low levels of oxygen (acute hypoxia), that avoid multiple effects of chronic hypoxia may be used to probe the oxygen sensing pathway of the heart. Here we explore the oxygen sensing pathway, focusing primarily on cellular surface membrane proteins that are first exposed to low PO₂. Such studies suggest that acute hypoxia primarily targets the cardiac calcium channels, where either the channel itself or moieties closely associated with it, for instance, heme-oxygenase-2 (HO-2) interacting through kinase phosphorylation, signals the α-subunit of the channel as to the altered levels of PO₂. Amino acids 1572-1651, the CaMKII phosphorylation sites (S1487 and S1545), CaM-binding site (I1624, Q1625) and Ser1928 of the carboxyl tail of the α-subunit appear to be critical residues that sense oxygen. Future studies in HO-2 knockout mice or CRISPR/Cas9 gene-edited hiPSC-CMs that reduce CaM-binding affinity are likely to provide deeper insights in the O₂-sensinsing mechanisms.

Apatite nanosheets inhibit initial smooth muscle cell proliferation by damaging cell membrane

Understanding how nanostructured coatings interact with cells is related to how they manipulate cell behaviors and is therefore critical for designing better biomaterials. The apatite nanosheets were deposited on metallic substrates via biomimetic precipitation. Cell viability of apatite nanosheets towards to smooth muscle cells (SMCs) were investigated, and the underlying mechanism was proposed. Apatite nanosheets presented inhibitory activity on SMC growth, and caused rupture of cell membranes. On the basis of measuring changes in intracellular calcium ([Ca²⁺]_i), observing cell contraction and apatite nanosheets - SMC interaction, it was found that calcium ions released from apatite led to rises in [Ca²⁺]_i, which induced vigorous SMC contraction on apatite nanosheets. Consequently, the cell membrane of individual SMCs was cut/penetrated by the sharp edges of apatite nanosheets, resulting in cell inactivation. This damage of cell membranes suggests a novel mechanism to manipulate cell viability, and may offer insights for the better design of calcium-based nanostructured coatings or other biomedical applications.

Melatonin as a Potential Neuroprotectant: Mechanisms in Subarachnoid Hemorrhage-Induced Early Brain Injury

Subarachnoid hemorrhage (SAH) is a common cerebrovascular disease with high mortality and disability rates. Despite progressive advances in drugs and surgical techniques, neurological dysfunction in surviving SAH patients have not improved significantly. Traditionally, vasospasm has been considered the main cause of death and disability following SAH, but anti-vasospasm therapy has not benefited clinical prognosis. Many studies have proposed that early brain injury (EBI) may be the primary factor influencing the prognosis of SAH. Melatonin is an indole hormone and is the main hormone secreted by the pineal gland, with low daytime secretion levels and high nighttime secretion levels. Melatonin produces a wide range of biological effects through the neuroimmune endocrine network, and participates in various physiological activities in the central nervous system, reproductive system, immune system, and digestive system. Numerous studies have reported that melatonin has extensive physiological and pharmacological effects such as anti-oxidative stress, anti-inflammation, maintaining circadian rhythm, and regulating cellular and humoral immunity. In recent years, more and more studies have been conducted to explore the molecular mechanism underlying melatonin-induced neuroprotection. The studies suggest beneficial effects in the recovery of intracerebral hemorrhage, cerebral ischemia-reperfusion injury, spinal cord injury, Alzheimer’s disease, Parkinson’s disease and meningitis through anti-inflammatory, antioxidant and anti-apoptotic mechanisms. This review summarizes the recent studies on the application and mechanism of melatonin in SAH.

The Use of Wearable Pulse Oximeters in the Prompt Detection of Hypoxemia and During Movement: Diagnostic Accuracy Study

Background

Commercially available wearable (ambulatory) pulse oximeters have been recommended as a method for managing patients at risk of physiological deterioration, such as active patients with COVID-19 disease receiving care in hospital isolation rooms; however, their reliability in usual hospital settings is not known.

Objective

We report the performance of wearable pulse oximeters in a simulated clinical setting when challenged by motion and low levels of arterial blood oxygen saturation (SaO₂).

Methods

The performance of 1 wrist-worn (Wavelet) and 3 finger-worn (CheckMe O2+, AP-20, and WristOx2 3150) wearable, wireless transmission–mode pulse oximeters was evaluated. For this, 7 motion tasks were performed: at rest, sit-to-stand, tapping, rubbing, drinking, turning pages, and using a tablet. Hypoxia exposure followed, in which inspired gases were adjusted to achieve decreasing SaO₂ levels at 100%, 95%, 90%, 87%, 85%, 83%, and 80%. Peripheral oxygen saturation (SpO₂) estimates were compared with simultaneous SaO₂ samples to calculate the root-mean-square error (RMSE). The area under the receiver operating characteristic curve was used to analyze the detection of hypoxemia (ie, SaO₂<90%).

Results

SpO₂ estimates matching 215 SaO₂ samples in both study phases, from 33 participants, were analyzed. Tapping, rubbing, turning pages, and using a tablet degraded SpO₂ estimation (RMSE>4% for at least 1 device). All finger-worn pulse oximeters detected hypoxemia, with an overall sensitivity of ≥0.87 and specificity of ≥0.80, comparable to that of the Philips MX450 pulse oximeter.

Conclusions

The SpO₂ accuracy of wearable finger-worn pulse oximeters was within that required by the International Organization for Standardization guidelines. Performance was degraded by motion, but all pulse oximeters could detect hypoxemia. Our findings support the use of wearable, wireless transmission–mode pulse oximeters to detect the onset of clinical deterioration in hospital settings.

Trial Registration

ISRCTN Registry 61535692; http://www.isrctn.com/ISRCTN61535692

International Registered Report Identifier (IRRID)

RR2-10.1136/bmjopen-2019-034404

CT-Based Classification of Acute Cerebral Edema: Association with Intracranial Pressure and Outcome

BACKGROUND AND PURPOSE

Brain edema after acute cerebral lesions may lead to raised intracranial pressure (ICP) and worsen outcome. Notwithstanding, no CT-based scoring system to quantify edema formation exists. This retrospective correlative analysis aimed to establish a valid and definite CT score quantifying brain edema after common acute cerebral lesions.

METHODS

A total of 169 CT investigations in 60 patients were analyzed: traumatic brain injury (TBI; n = 47), subarachnoid hemorrhage (SAH; n = 70), intracerebral hemorrhage (ICH; n = 42), and ischemic stroke (n = 10). Edema formation was classified as 0: no edema, 1: focal edema confined to 1 lobe, 2: unilateral edema > 1 lobe, 3: bilateral edema, 4: global edema with disappearance of sulcal relief, and 5: global edema with basal cisterns effacement. ICP and Glasgow Outcome Score (GOS) were correlated to edema formation.

RESULTS

Median ICP values were 12.0, 14.0, 14.9, 18.2, and 25.9 mm Hg in grades 1-5, respectively. Edema grading significantly correlated with ICP (r = .51; P < .0001) in focal and global cerebral edema, particularly in patients with TBI, SAH, and ICH (r = .5, P < .001; r = .5; P < .0001; r = .6, P < .0001, respectively). At discharge, 23.7% of patients achieved a GOS of 5 or 4, 65.0% reached a GOS of 3 or 2, and 11.9% died (GOS 1). CT-score of cerebral edema in all patients correlated with outcome (r = -.3, P = .046).

CONCLUSION

The proposed CT-based grading of extent of cerebral edema significantly correlated with ICP and outcome in TBI, SAH, and ICH patients and might be helpful for standardized description of CT-images and as parameter for clinical studies, for example, measuring effects of antiedematous therapies.

Cerebrospinal Fluid Concentrations of Nimodipine Correlate With Long-term Outcome in Aneurysmal Subarachnoid Hemorrhage: Pilot Study

OBJECTIVES

The aim was to evaluate plasma and cerebrospinal fluid (CSF) nimodipine concentrations in patients with aneurysmal subarachnoid hemorrhage and their correlation with clinical outcome.

METHODS

Nimodipine infusion was started at 1 mg/h and increased up to 2 mg/h and continued up to 21 days in surviving patients. Arterial and CSF samples were collected at least after 24 hours of stable nimodipine dosing. Delayed cerebral ischemia and vasospasm were documented by new neurological deficits and neuroimaging. The clinical outcome was assessed at 9 months by the modified Rankin scale.

RESULTS

Twenty-three patients were enrolled. Nimodipine dose was 13 to 38 μg/kg per hour. Nimodipine arterial and CSF concentrations were 24.9 to 71.8 ng/mL and 37 to 530 pg/mL, respectively. Dose did not correlate with arterial or CSF concentrations. Arterial concentrations did not correlate with corresponding CSF concentrations. Doses and arterial concentrations did not correlate with the clinical outcome and were not associated with the occurrence of delayed cerebral ischemia. However, patients with no significant disability after 9 months of hemorrhage showed significantly higher CSF nimodipine concentrations (P = 0.015) and CSF-to-plasma ratios (P = 0.011) compared with patients who showed some degree of disability or who died.

CONCLUSIONS

Cerebrospinal fluid nimodipine concentrations measured during hospital drug infusion showed a correlation with long-term clinical outcome in patients with aneurysmal subarachnoid hemorrhage. These very preliminary data suggest that CSF concentrations monitoring may have some value in managing these patients.

Protocol for a prospective, controlled, cross-sectional, diagnostic accuracy study to evaluate the specificity and sensitivity of ambulatory monitoring systems in the prompt detection of hypoxia and during movement

INTRODUCTION

Automated continuous ambulatory monitoring may provide an alternative to intermittent manual vital signs monitoring. This has the potential to improve frequency of measurements, timely escalation of care and patient safety. However, a major barrier to the implementation of these wearable devices in the ward environment is their uncertain reliability, efficiency and data fidelity. The purpose of this study is to test performance of selected devices in a simulated clinical setting including during movement and low levels of peripheral oxygen saturation.

METHODS AND ANALYSIS

This is a single centre, prospective, controlled, cross-sectional, diagnostic accuracy study to determine the specificity and sensitivity of currently available ambulatory vital signs monitoring equipment in the detection of hypoxia and the effect of movement on data acquisition. We will recruit up to 45 healthy volunteers who will attend a single study visit; starting with a movement phase and followed by the hypoxia exposure phase where we will gradually decrease saturation levels down to 80%. We will simultaneously test one chest patch, one wrist worn only and three wrist worn with finger probe devices against 'clinical standard 'and 'gold standard' references. We will measure peripheral oxygen saturations, pulse rate, heart rate and respiratory rate continuously and arterial blood gases intermittently throughout the study.

ETHICS AND DISSEMINATION

This study has received ethical approval by the East of Scotland Research Ethics Service REC 2 (19/ES/0008). The results will be broadly distributed through conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

ISRCTN61535692 registered on 10/06/2019.

The Oxford study of Calcium channel Antagonism, Cognition, Mood instability and Sleep (OxCaMS): study protocol for a randomised controlled, experimental medicine study

Background

The discovery that voltage-gated calcium channel genes such as CACNA1C are part of the aetiology of psychiatric disorders has rekindled interest in the therapeutic potential of L-type calcium channel (LTCC) antagonists. These drugs, licensed to treat hypertension and angina, have previously been used in bipolar disorder, but without clear results. Neither is much known about the broader effects of these drugs on the brain and behaviour.

Methods

The Oxford study of Calcium channel Antagonism, Cognition, Mood instability and Sleep (OxCaMS) is a high-intensity randomised, double-blind, placebo-controlled experimental medicine study on the effect of the LTCC antagonist nicardipine in healthy young adults with mood instability. An array of cognitive, psychiatric, circadian, physiological, biochemical and neuroimaging (functional magnetic resonance imaging and magnetoencephalography) parameters are measured during a 4-week period, with randomisation to drug or placebo on day 14. We are interested in whether nicardipine affects the stability of these measures, as well as its overall effects. Participants are genotyped for the CACNA1C risk polymorphism rs1006737.

Discussion

The results will clarify the potential of LTCC antagonists for repurposing or modification for use in psychiatric disorders in which cognition, mood and sleep are affected.

Trial registration

ISRCTN, ISRCTN33631053. Retrospectively registered on 8 June 2018 (applied 17 May 2018).

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3175-0) contains supplementary material, which is available to authorized users.

Vasogenic cerebral edema associated with the disability in activities of daily living in patients with chronic obstructive pulmonary disease

INTRODUCTION

The aim of this study was to explore whether patients with chronic obstructive pulmonary disease (COPD) develop vasogenic cerebral edema, and whether this edema contributes to the COPD-related disability.

METHODS

Eighteen stable patients with COPD and 17 matched healthy volunteers were enrolled. Apparent diffusion coefficient (ADC) values were calculated by voxel-based analysis using DTI-Studio software based on diffusion tensor imaging. COPD-related disability was calculated using activities of daily living (ADL) scale.

RESULTS

In patients with COPD, ADC increased in the white matter fiber tracts including the bilateral anterior cingulum and posterior corpus callosum and in the white matter fibers connecting the bilateral insular cortices, sub-lobar cortices, and pars triangularis cortices and the left rectus and olfactory gyrus. However, after further controlling for cigarette smoking, the difference in ADC values in the posterior corpus callosum between groups disappeared. Patients with COPD had significantly higher scores in ADL than that in controls. Moreover, ADL scores were positively correlated with the increased regional ADC values.

CONCLUSION

Vasogenic cerebral edema occurs in patients with COPD. Cigarette smoking may be a risk factor for COPD-related vasogenic edema. Vasogenic cerebral edema may be related to the COPD-related ADL impairment.