Elevated calcium after acute ischemic stroke: association with a poor short-term outcome and long-term mortality

Can baseline serum calcium levels predict outcomes of intracerebral hemorrhage? A systematic review and meta-analysis

OBJECTIVE

The prognostic role of baseline calcium levels in patients with intracerebral hemorrhage (ICH) is conflicting. We aimed to conduct the first meta-analysis in the literature to examine if baseline calcium levels can predict outcomes after ICH.

METHODS

English-language studies listed on the databases of Embase, PubMed, ScienceDirect, and Web of Science were searched up to 20th November 2023. Meta-analysis was conducted for baseline hematoma volume, hematoma expansion, unfavorable functional outcome, and mortality.

RESULTS

Ten studies were included. Meta-analysis showed that patients with hypocalcemia have significantly higher baseline hematoma volume (MD: 8.6 95 % CI: 3.30, 13.90 I2 = 88 %) but did not have a higher risk of hematoma expansion (OR: 1.82 95 % CI: 0.89, 3.73 I2 = 82 %). Meta-analysis of crude (OR: 1.86 95 % CI: 1.25, 2.78 I2 = 63 %) and adjusted data (OR: 2.05 95 % CI: 1.27, 3.28 I2 = 64 %) showed those with hypocalcemia had a significantly higher risk of unfavorable functional outcomes. Meta-analysis of both crude (OR: 2.09 95 % CI: 1.51, 2.88 I2 = 80 %) and adjusted data (OR: 1.38 95 % CI: 1.14, 1.69 I2 = 70 %) also demonstrated a significantly higher risk of mortality in patients with hypocalcemia.

CONCLUSION

Baseline serum calcium may have a prognostic role in ICH. Hypocalcemia at baseline may lead to large hematoma volume and poor functional and survival outcomes. However, there seems to be no relation between hypocalcemia and the risk of hematoma expansion. Further studies examining the role of calcium on ICH prognosis are needed.

Red cell distribution width to total serum calcium ratio and in-hospital mortality risk in patients with acute ischemic stroke: A MIMIC-IV retrospective analysis

We investigated the relationship among red cell distribution width (RDW), to total serum calcium (TSC) ratio (RCR), and in-hospital mortality in patients with acute ischemic stroke (AIS). This study was a retrospective analysis. The data of 2700 AIS patients was retrospectively analyzed from the Medical Information Mart for Intensive Care database (version IV). The main outcome of interest was in-hospital mortality. A Cox proportional hazards regression model was used to determine whether RCR was independently associated with in-hospital mortality. The Kaplan-Meier method was used to plot the survival curves for RCR. Subgroup analyses were performed to measure the mortality across various subgroups. The area under curve (AUC) of receiver operating characteristic curve (ROC) was calculated to ascertain the quality of RCR as a predictor of in-hospital mortality in patients with AIS. In the multivariate analysis, statistically significant differences were identified in age, ethnicity, length of ICU stay, mechanical ventilation, sequential organ failure assessment (SOFA) score, RDW, hemoglobin, RCR, whether taking anticoagulants, hyperlipidemia, and atrial fibrillation (P < .05). A threshold inflection point value of 1.83 was obtained through a two-piecewise regression model. There was a non-linear relationship between RCR and hospital mortality in patients with AIS. The hazard ratio (HR) and the 95% confidence intervals (CI) on the right and left of the inflection point were 0.93 (0.57-1.51; P = .7660) and 2.96 (1.37-6.42; P = .0060), respectively. The Kaplan-Meier curve indicated that survival rates were higher when RCR was ≤ 1.83 and lower when RDW was > 1.83 after adjustment for age, gender, BMI, ethnicity. The area under curve (AUC) of RCR was 0.715. A higher RCR was associated with an increased risk of in-hospital mortality in patients with AIS.

Association between serum calcium and prognosis in patients with acute ischemic stroke in ICU: analysis of the MIMIC-IV database

BACKGROUND

While serum Ca has proven to be a reliable predictor of mortality across various diseases, its connection with the clinical outcomes of ischemic stroke (IS) remains inconclusive. Our research aimed to explore the relationships between serum total Ca (tCa) and serum ionized Ca (iCa) and mortality among acute IS (AIS) patients.

METHODS

We gathered data from 1773 AIS patients in the Medical Information Mart for Intensive Care Database IV, including baseline demographic data, comorbidities, vital signs, laboratory-based data, and scoring systems. Endpoints for the study encompassed 30-d, 90-d, and 365-d all-cause mortalities. Employing restricted cubic spline Cox regression, we explored potential nonlinear relationships between admission serum iCa and tCa levels and mortality. Participants were categorized into four groups based on serum iCa and tCa quartiles. Multivariable Cox regression analysis was then conducted to evaluate the independent association of iCa and tCa quartiles with all-cause mortality.

RESULTS

The restricted cubic spline revealed a U-shaped association between iCa and 30-d and 90-d mortality (P<0.05), while the relationship between iCa and 365-d mortality was linear (P<0.05). After adjusting for confounders, multivariable Cox analysis demonstrated that the lowest serum iCa level quartile was independently associated with increased risks of 30-d, 90-d, and 365-d mortality. Similarly, the highest serum iCa level quartile was independently associated with increased risks of 30-d and 90-d mortality, but not 365-d mortality. Notably, serum tCa level showed no association with increased risks of 30-d, 90-d, and 365-d mortality.

CONCLUSIONS

Our findings suggest that serum iCa, rather than tCa, is linked to ischemic stroke prognosis. Both high and low serum iCa levels are associated with poor short-term prognosis, while only low serum iCa is associated with poor long-term prognosis in AIS patients.

Modelling Cross Talk in the Spatiotemporal System Dynamics of Calcium, IP3 and Nitric Oxide in Neuron Cells

The bioenergetic system of calcium ([Ca2+]), inositol 1, 4, 5-trisphophate (IP3) and nitric oxide (NO) regulate the diverse mechanisms in neurons. The dysregulation in any or all of the calcium, IP3 and nitric oxide dynamics may cause neurotoxicity and cell death. Few studies are noted in the literature on the interactions of two systems like [Ca2+] with IP3 and [Ca2+] with nitric oxide in neuron cells, which gives limited insights into regulatory and dysregulatory processes in neuron cells. But, no study is available on the cross talk in dynamics of three systems [Ca2+], IP3 and NO in neurons. Thus, the cross talk in the system dynamics of [Ca2+], IP3 and NO regulation processes in neurons have been studied using mathematical model. The two-way feedback process between [Ca2+] and IP3 and two-way feedback process between [Ca2+] and NO through cyclic guanosine monophosphate (cGMP) with plasmalemmal [Ca2+]-ATPase (PMCA) have been incorporated in the proposed model. This coupling handles the indirect two-way feedback process between IP3 and nitric oxide in neuronal cells automatically. The numerical outcomes were acquired by employing the finite element method (FEM) with the Crank-Nicholson scheme (CNS). The present model incorporating the sodium-calcium exchanger (NCX) and voltage-gated calcium channel (VGCC) provides novel insights into the various regulatory and dysregulatory processes due to buffer, IP3-receptor, ryanodine receptor, cGMP kinetics through PMCA channel, etc. and their impacts on the interactive spatiotemporal system dynamics of [Ca2+], IP3 and NO in neurons. It is concluded that the behavior of different crucial mechanisms is quite different for interactions of two systems of [Ca2+] and NO and the interactions of three systems of [Ca2+], IP3 and nitric oxide in neuronal cell due to mutual regulatory adjustments. The association of several neurological disorders with the alterations in calcium, IP3 and NO has been explored in neurons.

Elevated Calcium after Acute Ischemic Stroke Predicts Severity and Prognosis

The aim of this study is to investigate whether there is a correlation between serum calcium levels and clinical severity or functional outcome at discharge in Chinese patients with acute ischemic stroke. Data from 339 patients admitted to our hospital between July 2020 and July 2021 were analyzed. Baseline demographic and clinical information was collected within 24 h of admission, including serum calcium levels, stroke severity (measured by the National Institutes of Health Stroke Scale [NIHSS] score), and lesion volumes. The modified Rankin Scale [mRS] assessed functional outcomes at discharge. Our analysis showed that the median age of patients included in the study was 65 years (interquartile range [IQR], 60-70), and 60.8% were men. We found a positive correlation between serum calcium levels and stroke severity (r[spearman] = 0.266, P < 0.001), with calcium levels increasing as stroke severity increased. In a subgroup of 188 patients with available MRI data, serum calcium concentrations positively correlated with infarct size. Furthermore, in multivariate analysis, a calcium serum level in the highest quartile was associated with a higher risk of unfavorable outcome (odds ratios [OR] = 3.27; 95% confidence intervals [CI] = 1.91-5.59; P < 0.001). In conclusion, our study indicates that higher calcium serum levels are associated with stroke severity and early neurologic outcome after acute ischemic stroke, indicating that calcium may serve as a prognostic biomarker for stroke in Chinese patients.

Study of disorders in regulatory spatiotemporal neurodynamics of calcium and nitric oxide

Experimental studies have reported the dependence of nitric oxide (NO) on the regulation of neuronal calcium ([Ca2+]) dynamics in neurons. But, there is no model available to estimate the disorders caused by various parameters in their regulatory dynamics leading to various neuronal disorders. A mathematical model to analyze the impacts due to alterations in various parameters like buffer, ryanodine receptor, serca pump, source influx, etc. leading to regulation and dysregulation of the spatiotemporal calcium and NO dynamics in neuron cells is constructed using a system of reaction-diffusion equations. The numerical simulation is performed with the finite element approach. The disturbances in the different constitutive processes of [Ca2+] and nitric oxide including source influx, buffer mechanism, ryanodine receptor, serca pump, IP3 receptor, etc. can be responsible for the dysregulation in the [Ca2+] and NO dynamics in neurons. Also, the results reveal novel information about the magnitude and intensity of disorders in response to a range of alterations in various parameters of this neuronal dynamics, which can cause dysregulation leading to neuronal diseases like Parkinson's, cerebral ischemia, trauma, etc.

Role of microRNA-34a in blood-brain barrier permeability and mitochondrial function in ischemic stroke

Over the past decade, there has been an uptick in the number of studies conducting research on the role of microRNA (miRNA) molecules in stroke. Among these molecules, miR-34a has emerged as a significant player, as its levels have been observed to exhibit a substantial rise following ischemic events. Elevated levels of miR-34a have been found to have multiple effects, including the modulation of inflammatory molecules involved in the post-stroke recovery process, as well as negative effects on the blood-brain barrier (BBB) permeability. Interestingly, the increase of miR-34a appears to increase BBB permeability post stroke, through the negative effect on mitochondrial function. The strength of mitochondrial function is crucial for limiting para-cellular permeability and maintaining the structural integrity of the BBB. Furthermore, the activation of ischemic repair mechanisms and the reduction of ischemic event damage depend on healthy mitochondrial activity. This review aims to emphasize the involvement of miR-34a in ischemic stroke, specifically its interaction with mitochondrial genes in cerebrovascular endothelial cells, the effect on mitochondrial function, and lastly its regulatory role in BBB permeability. A comprehensive understanding of the role of miR-34a in maintaining BBB integrity and its contribution to the pathogenesis of stroke holds significant value in establishing a foundation for the development of future therapeutics and diagnostic markers.

Effects of Prolonged Serum Calcium Suppression during Extracorporeal Cardiopulmonary Resuscitation in Pigs

Controlled reperfusion by monitoring the blood pressure, blood flow, and specific blood parameters during extracorporeal reperfusion after cardiac arrest has the potential to limit ischemia-reperfusion injury. The intracellular calcium overload as part of the ischemia-reperfusion injury provides the possibility for the injury to be counteracted by the early suppression of serum calcium with the aim of improving survival and the neurological outcome. We investigated the effects of prolonged serum calcium suppression via sodium citrate during extracorporeal resuscitation using the CARL protocol (CARL-controlled automated reperfusion of the whole body) compared to a single-dose approach in a porcine model after prolonged cardiac arrest. A control group (N = 10) was resuscitated after a 20 min cardiac arrest, initially lowering the intravascular calcium with the help of a single dose of sodium citrate as part of the priming solution. Animals in the intervention group (N = 13) received additional sodium citrate for the first 15 min of reperfusion. In the control group, 9/10 (90.0%) animals survived until day 7 and 7/13 (53.8%) survived in the intervention group (p = 0.09). A favorable neurological outcome on day 7 after the cardiac arrest was observed in all the surviving animals using a species-specific neurological deficit score. The coronary perfusion pressure was significantly lower with a tendency towards more cardiac arrhythmias in the intervention group. In conclusion, a prolonged reduction in serum calcium levels over the first 15 min of reperfusion after prolonged cardiac arrest tended to be unfavorable regarding survival and hemodynamic variables compared to a single-dose approach in this animal model.

Association of Serum Calcium With Infarct Size and Severity in Acute Ischemic Stroke: A Rural Hospital-Based Cross-Sectional Study

Background One of the major mediators of ischemic neuronal cell death is calcium. It has been found that elevated serum calcium is associated with a better prognosis in patients with ischemic stroke. This study highlights the association of serum calcium, albumin-corrected calcium, and ionic calcium with the size of acute ischemic stroke as well as severity outcome in terms of the National Institutes of Health Stroke Scale (NIHSS) score and Barthel Index. Methods This cross-sectional study was conducted on 85 cases of acute ischemic stroke (based on a computerized tomography scan of the brain) from September 2019 to October 2021. All included patients had undergone complete clinical history, systemic examination, as well as estimation of serum total calcium, albumin corrected calcium, and ionic calcium. NIHSS score and Barthel Index were used to access the severity of each subject.  Results A significant positive correlation was seen between infarct size with NIHSS with a correlation coefficient of 0.35. A significant negative correlation was seen between infarct size with serum calcium, albumin-corrected calcium, and Barthel Index with a correlation coefficient of -0.483, -0.354, and -0.365 respectively. No correlation was seen between infarct size and ionic calcium with a correlation coefficient of 0.082. Conclusion It can be concluded that higher normal levels of serum calcium and albumin-corrected calcium are associated with a smaller-sized infarct and had less severity index among patients with acute ischemic stroke.

Mechanistic insights of neuronal calcium and IP3 signaling system regulating ATP release during ischemia in progression of Alzheimer's disease

The mechanisms of calcium ([Ca²⁺]) signaling in various human cells have been widely analyzed by scientists due to its crucial role in human organs like the heartbeat, muscle contractions, bone activity, brain functionality, etc. No study is reported for interdependent [Ca²⁺] and IP₃ mechanics regulating the release of ATP in neuron cells during Ischemia in Alzheimer's disease advancement. In the present investigation, a finite element method (FEM) is framed to explore the interdependence of spatiotemporal [Ca²⁺] and IP₃ signaling mechanics and its role in ATP release during Ischemia as well as in the advancement of Alzheimer's disorder in neuron cells. The results provide us insights of the mutual spatiotemporal impacts of [Ca²⁺] and IP₃ mechanics as well as their contributions to ATP release during Ischemia in neuron cells. The results obtained for the mechanics of interdependent systems differ significantly from the results of simple independent system mechanics and provide new information about the processes of the two systems. From this study, it is concluded that neuronal disorders cannot only be simply attributed to the disturbance caused directly in the processes of calcium signaling mechanics, but also to the disturbances caused in IP₃ regulation mechanisms impacting the calcium regulation in the neuron cell and ATP release.

Retinoic Acid Prevents the Neuronal Damage Through the Regulation of Parvalbumin in an Ischemic Stroke Model

Ischemic stroke is a neurological disease that causes brain damage by increasing oxidative stress and ion imbalance. Retinoic acid is a major metabolite of vitamin A and regulates oxidative stress, calcium homeostasis, and cell death. Intracellular calcium is involved in neuronal growth and synaptic plasticity. Parvalbumin is a calcium-binding protein that is mainly expressed in brain. In this study, we investigated whether retinoic acid has neuroprotective effects by controlling intracellular calcium concentration and parvalbumin expression in ischemic brain damage. Middle cerebral artery occlusion (MCAO) was performed to induce cerebral ischemia. Retinoic acid (5 mg/kg) or vehicle was injected into the abdominal cavity for four days before surgery and cerebral cortices were collected 24 h after MCAO for further studies. MCAO damage induced neurological deficits and histopathological changes and decreased parvalbumin expression. However, retinoic acid treatment alleviated these changes. In cultured neurons, glutamate (5 mM) exposure induced neuronal cell death, increased intracellular calcium concentration, and decreased parvalbumin expression. Retinoic acid treatment attenuated these changes against glutamate toxicity in a dose-dependent manner. It also regulates glutamate induced change in bcl-2 and bax expression. The mitigation effects of retinoic acid were greater under non-transfection conditions than under parvalbumin siRNA transfection conditions. Our findings showed that retinoic acid modulates intracellular calcium concentration and parvalbumin expression and prevents apoptosis in ischemic brain injury. In conclusion, retinoic acid contributes to the preservation of neurons from ischemic stroke by controlling parvalbumin expression and apoptosis-related proteins.

The association of admission ionized calcium with outcomes of thrombolysed patients with anterior circulation ischemic stroke

BACKGROUND AND PURPOSE

The relationship between ionized calcium and prognosis of ischemic stroke is controversial. We aim to determine the relationship of admission ionized calcium levels with acute ischemic stroke (AIS) after intravenous thrombolysis (IVT).

METHODS

Consecutive anterior circulation AIS patients treated with recombinant tissue plasminogen activator (rt-PA) were retrospectively enrolled. According to ionized calcium quartiles, the patients were divided into four groups and clinical data were analyzed between groups. Ionized calcium was entered into logistic regression analysis in two models, separately: model 1, calcium as a continuous variable (per 1-mmol/L increase), and model 2, calcium as the four-categorized variable (being collapsed into quartiles: Q1-Q4). Early neurologic improvement (ENI) was defined as improvement of four or more points at 24 h after intravenous rt-PA, while long-term good outcome as the modified Rankin Scale (mRS) 0-1 at 90 days.

RESULTS

A total of 546 patients met the study criteria (mean age was 63.51 ± 11.26 years and 365 [66.8%] were men). The median admission National Institute of Health Stroke Scale was 9 (range 4 to 15). When not adjusted, in model 1: ionized calcium was related to good outcome (odds ratio [OR] 69.061, 95%CI: 1.638-2911.111, p=0.027), but not ENI (OR 14.097, 95%CI: 0.133-1492.596, p=0.266); in model 2: compared with Q4, while good outcome was less common in Q1 (OR 0.623, 95%CI: 0.388-0.999, p=0.049). After adjusting for confounding factors, calcium in Q2 (OR 0.502, 95%CI: 0.253-0.997, p=0.049) was independently associated with ENI, but no matter as a continuous variable or categorized variable, ionized calcium displayed no association with a good outcome.

CONCLUSION

The current results found that ionized calcium might be associated with early neurological improvement, but had no association with 3 months' outcome in anterior circulation AIS patients after IVT.

Glial Cells Response in Stroke

As the second-leading cause of death, stroke faces several challenges in terms of treatment because of the limited therapeutic interventions available. Previous studies primarily focused on metabolic and blood flow properties as a target for treating stroke, including recombinant tissue plasminogen activator and mechanical thrombectomy, which are the only USFDA approved therapies. These interventions have the limitation of a narrow therapeutic time window, the possibility of hemorrhagic complications, and the expertise required for performing these interventions. Thus, it is important to identify the contributing factors that exacerbate the ischemic outcome and to develop therapies targeting them for regulating cellular homeostasis, mainly neuronal survival and regeneration. Glial cells, primarily microglia, astrocytes, and oligodendrocytes, have been shown to have a crucial role in the prognosis of ischemic brain injury, contributing to inflammatory responses. They play a dual role in both the onset as well as resolution of the inflammatory responses. Understanding the different mechanisms driving these effects can aid in the development of therapeutic targets and further mitigate the damage caused. In this review, we summarize the functions of various glial cells and their contribution to stroke pathology. The review highlights the therapeutic options currently being explored and developed that primarily target glial cells and can be used as neuroprotective agents for the treatment of ischemic stroke.

Association of serum calcium levels with clinical severity of ischemic stroke at the time of admission as defined by NIHSS score: A cross-sectional, observational study

Introduction

Calcium plays an important role in the pathogenesis of ischemic cell damage. Intracellular calcium accumulation leads to neuronal damage by triggering the cycle of cytotoxic events. In this study, the association of serum calcium levels with clinical severity of ischemic stroke as defined by the National Institute of Health Stroke Scale (NIHSS) score was evaluated.

Materials and Methods

After obtaining ethical approval from the institutional ethics committee, data was collected from 60 ischemic stroke patients, who were divided into two groups of 30 patients each: group 1 with serum ionized calcium less than 4.5 mg/dl and group 2 with serum ionized calcium levels more than 4.5 mg/dl. The stroke severity in the two groups was assessed using the NIHSS score.

Results

The severity of ischemic stroke according to the NIHSS score was greater in patients with low serum ionized calcium levels compared to the severity of ischemic stroke in patients with normal serum ionized calcium levels.

Conclusion

Serum ionized calcium certainly plays a role in the pathogenesis of ischemic stroke by influencing the cycle of cytotoxic events that result in ischemic cell death. This study showed that the severity of ischemic stroke was greater in patients with low serum ionized calcium levels compared to patients with normal serum ionized calcium levels.

Higher serum albumin-corrected calcium levels are associated with revascularization and poor outcome after mechanical thrombectomy

Background

Serum calcium abnormalities have been determined to be associated with the risk and outcome of stroke. The aim of the present study was to examine the associations of serum calcium with vascular recanalization, symptomatic intracranial haemorrhage and functional outcome in stroke patients after mechanical thrombectomy.

Methods

A total of 192 patients treated with mechanical thrombectomy for anterior circulation large vessel occlusion were consecutively included from August 2017 to June 2021. Serum calcium levels were measured on admission, and albumin-corrected calcium levels were calculated for subsequent analysis. Successful arterial revascularization was defined as a modified Thrombolysis in Cerebral Infarction scale score ≥ 2b. Symptomatic intracranial haemorrhage was assessed according to the European Cooperative Acute Stroke Study (ECASS) III criteria. Poor functional outcome was defined as a modified Rankin Scale score > 2 at 3 months.

Results

Patients with poor outcomes had higher albumin-corrected calcium levels than patients with good outcomes before (2.20 (2.10, 2.30) mmol/L vs. 2.13 (2.04, 2.24) mmol/L, P = 0.002), and after adjusting for other factors (AOR 95% CI, 1.812 (1.253, 2.621), P = 0.002). Patients with unsuccessful recanalization had higher albumin-corrected calcium levels than those with recanalization (2.26 (2.09, 2.46) mmol/L vs. 2.17 (2.07, 2.27) mmol/L, P = 0.029), and after adjusting for other factors (AOR 95% CI, 2.068 (1.214, 3.524)), P = 0.008). No association was found between albumin-corrected calcium and symptomatic intracranial haemorrhage.

Conclusions

Higher serum albumin-corrected calcium levels are independently associated with revascularization and poor outcome in stroke patients after mechanical thrombectomy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02856-2.

Admission Serum Calcium Level and Short-Term Mortality After Acute Ischemic Stroke: A Secondary Analysis Based on a Norwegian Retrospective Cohort

Background

Disturbed serum calcium levels are related to the risk of stroke. However, previous studies exploring the correlation between serum calcium and the clinical outcome of ischemic stroke (IS) have shown inconsistent results.

Object

The study aimed to investigate the relationship between admission serum calcium and 30-day mortality in patients with IS.

Methods

A total of 876 IS patients from a Norwegian retrospective cohort were included for secondary analysis. The exposure variable and the primary outcome were albumin-corrected serum calcium (ACSC) at baseline and all-cause mortality within 30 days after the first admission, respectively. Multivariable logistic regression analysis was used to estimate the risk of 30-day mortality according to ACSC levels. Moreover, the potential presence of a non-linear relationship was evaluated using two-piecewise linear regression with a smoothing function and threshold level analysis. The stability of the results was evaluated by unadjusted and adjusted models.

Results

The result of multiple regression analysis showed that ACSC at baseline was positively associated with the incidence of 30-day mortality after adjusting for the potential confounders (age, gender, serum glucose, hypertension, atrial fibrillation/atrial flutter, renal insufficiency, heart failure, chronic obstructive pulmonary disease, pneumonia, paralysis, and aphasia) (OR = 2.43, 95% CI 1.43–4.12). When ACSC was translated into a categorical variable, the ORs and 95% CIs in the second to the fourth quartile vs. the first quartile were 1.23 (0.56, 2.69), 1.16 (0.51, 2.65), and 2.13 (1.04, 4.38), respectively (P for trend = 0.03). Moreover, the results of two-piecewise linear regression and curve-fitting revealed a linear relationship between ACSC and 30-day mortality.

Conclusion

ACSC is positively associated with 30-day mortality in IS patients, and the relationship between them is linear.

Phosphodiesterase-5 Inhibitor Attenuates Anxious Phenotypes and Movement Disorder Induced by Mild Ischemic Stroke in Rats

Objective

Patients with mild ischemic stroke experience various sequela and residual symptoms, such as anxious behavior and deficits in movement. Few approaches have been proved to be effective and safe therapeutic approaches for patients with mild ischemic stroke by acute stroke. Sildenafil (SIL), a phosphodiesterase-5 inhibitor (PDE5i), is a known remedy for neurodegenerative disorders and vascular dementia through its angiogenesis and neurogenesis effects. In this study, we investigated the efficacy of PDE5i in the emotional and behavioral abnormalities in rats with mild ischemic stroke.

Methods

We divided the rats into four groups as follows (n=20, respectively) : group 1, naïve; group 2, middle cerebral artery occlusion (MCAo30); group 3, MCAo30+SIL-pre; and group 4, MCAo30+SIL-post. In the case of drug administration groups, single dose of PDE5i (sildenafil citrate, 20 mg/kg) was given at 30-minute before and after reperfusion of MCAo in rats. After surgery, we investigated and confirmed the therapeutic effect of sildenafil on histology, immunofluorescence, behavioral assays and neural oscillations.

Results

Sildenafil alleviated a neuronal loss and reduced the infarction volume. And results of behavior task and immunofluorescence shown possibility that anti-inflammation process and improve motor deficits sildenafil treatment after mild ischemic stroke. Furthermore, sildenafil treatment attenuated the alteration of theta-frequency rhythm in the CA1 region of the hippocampus, a known neural oscillatory marker for anxiety disorder in rodents, induced by mild ischemic stroke.

Conclusion

PDE5i as effective therapeutic agents for anxiety and movement disorders and provide robust preclinical evidence to support the development and use of PDE5i for the treatment of mild ischemic stroke residual disorders.

Transcranial magnetic stimulation in animal models of neurodegeneration

Brain stimulation techniques offer powerful means of modulating the physiology of specific neural structures. In recent years, non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation, have emerged as therapeutic tools for neurology and neuroscience. However, the possible repercussions of these techniques remain unclear, and there are few reports on the incisive recovery mechanisms through brain stimulation. Although several studies have recommended the use of non-invasive brain stimulation in clinical neuroscience, with a special emphasis on TMS, the suggested mechanisms of action have not been confirmed directly at the neural level. Insights into the neural mechanisms of non-invasive brain stimulation would unveil the strategies necessary to enhance the safety and efficacy of this progressive approach. Therefore, animal studies investigating the mechanisms of TMS-induced recovery at the neural level are crucial for the elaboration of non-invasive brain stimulation. Translational research done using animal models has several advantages and is able to investigate knowledge gaps by directly targeting neuronal levels. In this review, we have discussed the role of TMS in different animal models, the impact of animal studies on various disease states, and the findings regarding brain function of animal models after TMS in pharmacology research.

Diagnosis and prediction of COVID-19 severity: can biochemical tests and machine learning be used as prognostic indicators?

OBJECTIVE

This study aimed to implement and evaluate machine learning based-models to predict COVID-19' diagnosis and disease severity.

METHODS

COVID-19 test samples (positive or negative results) from patients who attended a single hospital were evaluated. Patients diagnosed with COVID-19 were categorised according to the severity of the disease. Data were submitted to exploratory analysis (principal component analysis, PCA) to detect outlier samples, recognise patterns, and identify important variables. Based on patients' laboratory tests results, machine learning models were implemented to predict disease positivity and severity. Artificial neural networks (ANN), decision trees (DT), partial least squares discriminant analysis (PLS-DA), and K nearest neighbour algorithm (KNN) models were used. The four models were validated based on the accuracy (area under the ROC curve).

RESULTS

The first subset of data had 5,643 patient samples (5,086 negatives and 557 positives for COVID-19). The second subset included 557 COVID-19 positive patients. The ANN, DT, PLS-DA, and KNN models allowed the classification of negative and positive samples with >84% accuracy. It was also possible to classify patients with severe and non-severe disease with an accuracy >86%. The following were associated with the prediction of COVID-19 diagnosis and severity: hyperferritinaemia, hypocalcaemia, pulmonary hypoxia, hypoxemia, metabolic and respiratory acidosis, low urinary pH, and high levels of lactate dehydrogenase.

CONCLUSION

Our analysis shows that all the models could assist in the diagnosis and prediction of COVID-19 severity.

Protection of the neurovascular unit from calcium-related ischemic injury by linalyl acetate

Calcium-related ischemic injury (CRII) can damage cells of the neurovascular unit (NVU). Here, we investigate the protective effects of linalyl acetate (LA) against CRII-induced NVU damage and evaluate the underlying mechanisms. The protective effects of LA in cell lines representative of NVU components (BEND, SH-SY5Y, BV2, and U373 cells) were evaluated following exposure to oxygen-glucose deprivation/reoxygenation alone (OGD/R-only) or OGD/R in the presence of 5 mM extracellular calcium ([Ca²⁺]_o) to mimic CRII. LA reversed damage under OGD/R-only conditions by blocking p47^phox/NADPH oxidase (NOX) 2 expression, reactive oxygen species (ROS) production, nitric oxide (NO) abnormality, and lactate dehydrogenase (LDH) release only in the BEND cells. However, under CRII-mimicking conditions, LA reversed NO abnormality and matrix metalloproteinase (MMP)-9 activation in the BEND murine brain endothelial cells; inhibited p47^phox expression in the human SH-SY5Y neural-like cells; decreased NOX2 expression and ROS generation in the BV2 murine microglial cells; and reduced p47^phox expression in the U373 human astrocyte-like cells. Importantly, LA protected against impairment of the neural cells, astrocytes, and microglia, all of which are cellular components of the NVU induced by exposure to CRII-mimicking conditions, by reducing LDH release. We found that LA exerted a protective effect in the BEND cells that may differ from its protective effects in other NVU cell types, following OGD/R-induced damage in the context of elevated [Ca²⁺]_o.

The multi-functional RNA-binding protein G3BP1 and its potential implication in neurodegenerative disease

Ras-GTPase-activating protein (GAP)-binding protein 1 (G3BP1) is a multi-functional protein that is best known for its role in the assembly and dynamics of stress granules. Recent studies have highlighted that G3BP1 also has other functions related to RNA metabolism. In the context of disease, G3BP1 has been therapeutically targeted in cancers because its over-expression is correlated with proliferation of cancerous cells and metastasis. However, evidence suggests that G3BP1 is essential for neuronal development and possibly neuronal maintenance. In this review, we will examine the many functions that are carried out by G3BP1 in the context of neurons and speculate how these functions are critical to the progression of neurodegenerative diseases. Additionally, we will highlight the similarities and differences between G3BP1 and the closely related protein G3BP2, which is frequently overlooked. Although G3BP1 and G3BP2 have both been deemed important for stress granule assembly, their roles may differ in other cellular pathways, some of which are specific to the CNS, and presents an opportunity for further exploration.

Extracellular ferritin contributes to neuronal injury in an in vitro model of ischemic stroke

Previous clinical and experimental studies have shown that neurological decline and poor functional outcome after acute ischemic stroke in humans are associated with high ferritin levels in serum and cerebrospinal fluid (CSF) within 24 h of ischemic stroke onset. The aim of the present study was to find out if and how high extracellular ferritin concentrations can increase the excitotoxicity effect in a neuronal cortical culture model of stroke. Extracellular ferritin (100 ng/ml) significantly increased the excitotoxic effect caused by excessive exogenous glutamate (50 μM and 100 μM) by leading to an increase in lipid peroxidation, a reduction in mitochondrial membrane potential, and a decrease in neuron viability. Extracellular apoferritin (100 ng/ml), the iron-free form of the protein, does not increase the excitotoxicity of glutamate, which proves that iron was responsible for the neurotoxic effect of the exogenous ferritin. We present evidence that extracellular ferritin iron exacerbates the neurotoxic effect induced by glutamate excitotoxicity and that the effect of ferritin iron is dependent of glutamate excitotoxicity. Our results support the idea that body iron overload is involved in the severity of the brain damage caused by stroke and reveal the need to control systemic iron homeostasis.

Environmental Enrichment Enhances Cav 2.1 Channel-Mediated Presynaptic Plasticity in Hypoxic-Ischemic Encephalopathy

Hypoxic–ischemic encephalopathy (HIE) is a devastating neonatal brain condition caused by lack of oxygen and limited blood flow. Environmental enrichment (EE) is a classic paradigm with a complex stimulation of physical, cognitive, and social components. EE can exert neuroplasticity and neuroprotective effects in immature brains. However, the exact mechanism of EE on the chronic condition of HIE remains unclear. HIE was induced by a permanent ligation of the right carotid artery, followed by an 8% O₂ hypoxic condition for 1 h. At 6 weeks of age, HIE mice were randomly assigned to either standard cages or EE cages. In the behavioral assessments, EE mice showed significantly improved motor performances in rotarod tests, ladder walking tests, and hanging wire tests, compared with HIE control mice. EE mice also significantly enhanced cognitive performances in Y-maze tests. Particularly, EE mice showed a significant increase in Ca_v 2.1 (P/Q type) and presynaptic proteins by molecular assessments, and a significant increase of Ca_v 2.1 in histological assessments of the cerebral cortex and hippocampus. These results indicate that EE can upregulate the expression of the Ca_v 2.1 channel and presynaptic proteins related to the synaptic vesicle cycle and neurotransmitter release, which may be responsible for motor and cognitive improvements in HIE.

Role of Calcium Homeostasis in Ischemic Stroke: A Review

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Stroke is the second most common cause of death worldwide. It occurs due to the insufficient supply of oxygen-rich blood to the brain. It is a complex disease with multiple associated risk factors including smoking, alcoholism, age, sex, ethnicity, etc. Calcium ions are known to play a vital role in cell death pathways, which is a ubiquitous intracellular messenger during and immediately after an ischemic period. Disruption in normal calcium hemostasis is known to be a major initiator and activator of the ischemic cell death pathway. Under Ischemic stroke conditions, glutamate is released from the neurons and glia which further activates the N-methyl-D-aspartate (NMDA) receptor and triggers the rapid translocation of Ca2+ from extracellular to intracellular spaces in cerebral tissues and vice versa. Various studies indicated that Ca2+ could have harmful effects on neurons under acute ischemic conditions. Mitochondrial dysfunction also contributes to delayed neuronal death, and it was established decades ago that massive calcium accumulation triggers mitochondrial damage. Elevated Ca2+ levels cause mitochondria to swell and release their contents. As a result oxidative stress and mitochondrial calcium accumulation activate mitochondrial permeability transition and lead to depolarization-coupled production of reactive oxygen species. This association between calcium levels and mitochondrial death suggests that elevated calcium levels might have a role in the neurological outcome in ischemic stroke. Previous studies have also reported that elevated Ca2+ levels play a role in the determination of infarct size, outcome, and recurrence of ischemic stroke. The current review has been compiled to understand the multidimensional role of altered Ca2+ levels in the initiation and alteration of neuronal death after ischemic attack. The underlying mechanisms understood to date have also been discussed.

The effects of trifluoperazine on brain edema, aquaporin-4 expression and metabolic markers during the acute phase of stroke using photothrombotic mouse model

Stroke is the second leading cause of death and the third leading cause of disability globally. Edema is a hallmark of stroke resulting from dysregulation of water homeostasis in the central nervous system (CNS) and plays the major role in stroke-associated morbidity and mortality. The overlap between cellular and vasogenic edema makes treating this condition complicated, and to date, there is no pathogenically oriented drug treatment for edema. Water balance in the brain is tightly regulated, primarily by aquaporin 4 (AQP4) channels, which are mainly expressed in perivascular astrocytic end-feet. Targeting AQP4 could be a useful therapeutic approach for treating brain edema; however, there is no approved drug for stroke treatment that can directly block AQP4. In this study, we demonstrate that the FDA-approved drug trifluoperazine (TFP) effectively reduces cerebral edema during the early acute phase in post-stroke mice using a photothrombotic stroke model. This effect was combined with an inhibition of AQP4 expression at gene and protein levels. Importantly, TFP does not appear to induce any deleterious changes on brain electrolytes or metabolic markers, including total protein or lipid levels. Our results support a possible role for TFP in providing a beneficial extra-osmotic effect on brain energy metabolism, as indicated by the increase of glycogen levels. We propose that targeting AQP4-mediated brain edema using TFP is a viable therapeutic strategy during the early and acute phase of stroke that can be further investigated during later stages to help in developing novel CNS edema therapies.

Integrated Genetics and Micronutrient Data to Inform the Causal Association Between Serum Calcium Levels and Ischemic Stroke

There has been an increased interest for observational studies or randomized controlled trials exploring the impact of calcium intake on cardiovascular diseases (CVD) including coronary artery disease (CAD) and ischemic stroke (IS). However, a direct relationship between total calcium intake and CVD has not been well established and remains controversial. Mendelian randomization (MR) studies have been performed to evaluate the causal association between serum calcium levels and CAD risk and found that increased serum calcium levels could increase the risk of CAD. However, MR analysis found no significant association between genetically higher serum calcium levels and IS as well as its subtypes. Hence, three MR studies reported inconsistent effects of serum calcium levels on CAD and IS. Here, we performed an updated MR study to investigate the association of serum calcium levels with the risk of IS using large-scale genome-wide association study (GWAS) datasets. We selected 14 independent genetic variants as the potential instrumental variables from a large-scale serum calcium GWAS dataset and extracted summary statistics corresponding to the 14 serum calcium genetic variants from the MEGASTROKE Consortium IS GWAS dataset. Interestingly, we found a significant association between serum calcium levels and IS risk using the robust inverse-variance weighted (IVW) and penalized robust IVW methods, with β = 0.243 and P = 0.002. Importantly, the MR results from the robust MR-Egger and penalized robust MR-Egger methods further supported the causal association between serum calcium levels and IS risk, with β = 0.256 and P = 0.005. Meanwhile, the estimates from other MR methods are also consistent with the above findings.

Hospital-Acquired Serum Ionized Calcium Derangements and Their Associations with In-Hospital Mortality

Background: The objective of this study was to report the incidence of in-hospital serum ionized calcium derangement and its impact on mortality. Methods: We included 12,599 non-dialytic adult patients hospitalized at a tertiary medical center from January 2009 to December 2013 with normal serum ionized calcium at admission and at least 2 in-hospital serum ionized calcium values. Using serum ionized calcium of 4.60–5.40 mg/dL as the normal reference range, in-hospital serum ionized calcium levels were categorized based on the presence of hypocalcemia and hypercalcemia in hospital. We performed logistic regression to assess the relationship of in-hospital serum ionized calcium derangement with mortality. Results: Fifty-four percent of patients developed new serum ionized calcium derangements: 42% had in-hospital hypocalcemia only, 4% had in-hospital hypercalcemia only, and 8% had both in-hospital hypocalcemia and hypercalcemia. In-hospital hypocalcemia only (OR 1.28; 95% CI 1.01–1.64), in-hospital hypercalcemia only (OR 1.64; 95% CI 1.02–2.68), and both in-hospital hypocalcemia and hypercalcemia (OR 1.73; 95% CI 1.14–2.62) were all significantly associated with increased in-hospital mortality, compared with persistently normal serum ionized calcium levels. Conclusions: In-hospital serum ionized calcium derangements affect more than half of hospitalized patients and are associated with increased in-hospital mortality.

Fluorescence Resonant Energy Transfer-Based Quantum Dot Sensor for the Detection of Calcium Ions

A simple optical aptasensor has been synthesized for the detection of calcium ions. This sensing approach employs a semiconductor quantum dot (QD)–gold nanoparticle as the donor–quencher pair and operates on the principle of fluorescence resonant energy transfer (FRET). On binding with calcium ions, the DNA aptamer undergoes a conformational change, which changes the distance between the quantum dot and the gold nanoparticle, conjugated on the 5′ terminal and 3′ terminal of the aptamer, respectively. This phenomenon results in the quenching of the quantum dot emission. In this sensor, a maximum quenching of 22.42 ± 0.71% has been achieved at 35 nM calcium ion concentration while the limit of detection has been determined to be 3.77 pM. The sensor has been found to have high specificity for calcium ions in comparison to other metal ions like sodium, magnesium, and potassium. The molecular apta-beacons also demonstrated successful endocytosis and FRET-based calcium ion detection in osteocyte cells when conjugated with a cell-penetrating peptide (DSS).

The Role of Serum Calcium Level in Intracerebral Hemorrhage Hematoma Expansion: Is There Any?

Spontaneous intracerebral hemorrhage (ICH) is a devastating form of stroke, with a high rate of mortality and morbidity. Even with the best current medical or surgical interventions, outcomes remain poor. The location and initial hematoma volume are strong predictors of mortality. Hematoma expansion (HE) is a further marker of poor prognosis that may be at least partly preventable. Several risk factors for HE have been identified, including baseline ICH volume, anticoagulation, and computed tomography angiography spot signs. Recent studies have shown the correlation of serum calcium (Ca⁺⁺) levels on admission with HE. Low serum Ca⁺⁺ level has been associated with larger hematoma volume at the time of presentation, HE, and worse outcome. Although the causal and mechanistic links between low serum Ca⁺⁺ level and HE are not well understood, several mechanisms have been proposed including coagulopathy, platelet dysfunction, and higher blood pressure (BP) in the context of low serum Ca⁺⁺ level. However, low serum Ca⁺⁺ level might be only a biomarker of the adaptive response due to acute inflammatory response following acute ICH. The purpose of the current review is to discuss the evidence regarding the possible role of low serum Ca⁺⁺ level on HE in acute ICH.

Impact of Admission Calcium-phosphate Product on 1-year Mortality among Hospitalized Patients

Background

Calcium-phosphate product is associated with mortality among patients with end-stage kidney disease on dialysis. However, clinical evidence among hospitalized patients is limited. The objective of this study was to investigate the relationship between admission calcium-phosphate product and 1-year mortality in hospitalized patients.

Materials and Methods

All adult patients admitted to a tertiary referral hospital in 2009-2013 were studied. Patients who had both available serum calcium and phosphate measurement within 24 h of hospital admission were included. Admission calcium-phosphate product (calcium × phosphate) was stratified based on its distribution into six groups: <21, 21-<27, 27-<33, 33-<39, 39-<45, and ≥45 mg²/dL². Multivariate cox proportional hazard analysis was performed to evaluate the association between admission calcium-phosphate product and 1-year mortality, using the calcium-phosphate product of 33-<39 mg²/dL² as the reference group.

Results

A total of 14,772 patients were included in this study. The mean admission calcium-phosphate product was 34.4 ± 11.3 mg²/dL². Of these patients, 3194 (22%) died within 1 year of hospital admission. In adjusted analysis, admission calcium-phosphate product of ≥45 mg²/dL² was significantly associated with increased 1-year mortality with hazard ratio of 1.41 (95% 95% confidence interval 1.25-1.67), whereas lower admission calcium-phosphate product was not significantly associated with 1-year mortality.

Conclusion

Elevated calcium-phosphate product was significantly associated with increased 1-year mortality in hospitalized patients.

Impact of Changes in Serum Calcium Levels on In-Hospital Mortality

Background and objectives: Calcium concentration is strictly regulated at both the cellular and systemic level, and changes in serum calcium levels can alter various physiological functions in various organs. This study aimed to assess the association between changes in calcium levels during hospitalization and mortality. Materials and Methods: We searched our patient database to identify all adult patients admitted to our hospital from January 1st, 2009 to December 31st, 2013. Patients with ≥2 serum calcium measurements during the hospitalization were included. The serum calcium changes during the hospitalization, defined as the absolute difference between the maximum and the minimum calcium levels, were categorized into five groups: 0–0.4, 0.5–0.9, 1.0–1.4, 1.5–1.9, and ≥2.0 mg/dL. Multivariable logistic regression was performed to assess the independent association between calcium changes and in-hospital mortality, using the change in calcium category of 0–0.4 mg/dL as the reference group. Results: Of 9868 patients included in analysis, 540 (5.4%) died during hospitalization. The in-hospital mortality progressively increased with higher calcium changes, from 3.4% in the group of 0–0.4 mg/dL to 14.5% in the group of ≥2.0 mg/dL (p < 0.001). When adjusted for age, sex, race, principal diagnosis, comorbidity, kidney function, acute kidney injury, number of measurements of serum calcium, and hospital length of stay, the serum calcium changes of 1.0–1.4, 1.5–1.9, and ≥2.0 mg/dL were significantly associated with increased in-hospital mortality with odds ratio (OR) of 1.55 (95% confidence interval (CI) 1.15–2.10), 1.90 (95% CI 1.32–2.74), and 3.23 (95% CI 2.39–4.38), respectively. The association remained statistically significant when further adjusted for either the lowest or highest serum calcium. Conclusion: Larger serum calcium changes in hospitalized patients were progressively associated with increased in-hospital mortality.

Cerebral ischemia induces TRPC6 via HIF1α/ZEB2 axis in the glomerular podocytes and contributes to proteinuria

Podocytes are specialized cells of the glomerulus and key component of the glomerular filtration apparatus (GFA). GFA regulates the permselectivity and ultrafiltration of blood. The mechanism by which the integrity of the GFA is compromised and manifest in proteinuria during ischemic stroke remains enigmatic. We investigated the mechanism of ischemic hypoxia-induced proteinuria in a middle cerebral artery occlusion (MCAO) model. Ischemic hypoxia resulted in the accumulation of HIF1α in the podocytes that resulted in the increased expression of ZEB2 (Zinc finger E-box-binding homeobox 2). ZEB2, in turn, induced TRPC6 (transient receptor potential cation channel, subfamily C, member 6), which has increased selectivity for calcium. Elevated expression of TRPC6 elicited increased calcium influx and aberrant activation of focal adhesion kinase (FAK) in podocytes. FAK activation resulted in the stress fibers reorganization and podocyte foot process effacement. Our study suggests overactive HIF1α/ZEB2 axis during ischemic-hypoxia raises intracellular calcium levels via TRPC6 and consequently altered podocyte structure and function thus contributes to proteinuria.

Measurement of cations, anions, and acetate in serum, urine, cerebrospinal fluid, and tissue by ion chromatography

Accurate quantification of cations and anions remains a major diagnostic tool in understanding diseased states. The current technologies used for these analyses are either unable to quantify all ions due to sample size/volume, instrument setup/method, or are only able to measure ion concentrations from one physiological sample (liquid or solid). Herein, we adapted a common analytical chemistry technique, ion chromatography and applied it to measure the concentration of cations; sodium, potassium, calcium, and magnesium (Na⁺, K⁺, Ca²⁺, and Mg²⁺) and anions; chloride, and acetate (Cl⁻, ⁻OAc) from physiological samples. Specifically, cations and anions were measured in liquid samples: serum, urine, and cerebrospinal fluid, as well as tissue samples: liver, cortex, hypothalamus, and amygdala. Serum concentrations of Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, and ⁻OAc (mmol/L): 138.8 ± 4.56, 4.05 ± 0.21, 4.07 ± 0.26, 0.98 ± 0.05, 97.7 ± 3.42, and 0.23 ± 0.04, respectively. Cerebrospinal fluid concentrations of Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, and ⁻OAc (mmol/L): 145.1 ± 2.81, 2.41 ± 0.26, 2.18 ± 0.38, 1.04 ± 0.11, 120.2 ± 3.75, 0.21 ± 0.05, respectively. Tissue Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, and ⁻OAc were also measured. Validation of the ion chromatography method was established by comparing chloride concentration between ion chromatography with a known method using an ion selective chloride electrode. These results indicate that ion chromatography is a suitable method for the measurement of cations and anions, including acetate from various physiological samples.

Serum magnesium level and hematoma expansion in patients with intracerebral hemorrhage

Spontaneous intracerebral hemorrhage (ICH) is a devastating subtype of stroke that results in significant rates of mortality and morbidities. The initial hematoma volume, hematoma expansion (HE), blood pressure (BP), and coagulopathy are considered strong predictors of clinical outcomes and mortality. Low serum magnesium (Mg⁺⁺) levels have been shown to be associated with larger initial hematoma and greater HE. Coagulopathy, platelet dysfunction, high BP, and increased inflammatory response might form the mechanistic link between low serum Mg⁺⁺ levels, larger hematoma size and greater HE. However, randomized clinical trials administering intravenous Mg⁺⁺ have shown no benefit over placebo in ICH patients. The confounding effect of hypocalcemia and a delay in Mg⁺⁺ trafficking across the blood-brain barrier might explain the futile results for intravenous Mg⁺⁺ therapy. In the current review, we will discuss the evidence regarding the possible role of low serum Mg⁺⁺ level on HE in acute ICH.

Impact of admission serum calcium levels on mortality in hospitalized patients

OBJECTIVES

To assess the relationship between admission serum calcium levels and in-hospital mortality in all hospitalized patients.

METHODS

All adult hospitalized patients who had admission serum calcium levels available between years 2009 and 2013 were enrolled. Admission serum calcium was categorized based on its distribution into six groups (<7.9, 7.9 to <8.4, 8.4 to <9.0, 9.0 to <9.6, 9.6 to <10.1, and ≥10.1 mg/dL). The odds ratio (OR) of in-hospital mortality by admission serum calcium, using the calcium category of 9.6-10.1 mg/dL as the reference group, was obtained by logistic regression analysis.

RESULTS

18,437 patients were studied. The lowest incidence of in-hospital mortality was associated with admission serum calcium within 9.6 to <10.1 mg/dL. A higher in-hospital mortality rate was observed in patients with serum calcium <9.6 and ≥10.1 mg/dL. Also, 38% and 33% of patients with admission serum calcium <7.9 and ≥10.1 mg/dL were on calcium supplements before admission, respectively. After adjusting for potential confounders, both serum calcium <8.4 and ≥10.1 mg/dL were associated with an increased risk of in-hospital mortality with ORs of 2.86 [95% confidence interval (CI) 1.98-4.17], 1.74 (95% CI 1.21-2.53), and 1.69 (95% CI 1.10-2.59) when serum calcium were within <7.9, 7.9 to <8.4, and ≥10.1 mg/dL, respectively.

CONCLUSION

Hypocalcemia and hypercalcemia on admission were associated with in-hospital mortality. Highest mortality risk is observed in patients with admission hypocalcemia (<7.9 mg/dL). One-third of patients with hypercalcemia on admission were on calcium supplements.

Calcium Dynamics as a Machine for Decoding Signals

Calcium (Ca²⁺) is considered one of the most-important biological cations, because it is implicated in cell physiopathology and cell fate through a finely tuned signaling system. In support of this notion, Ca²⁺ is the primary driver of cell proliferation and cell growth; however, it is also intimately linked to cell death. Functional abnormalities or mutations in proteins that mediate Ca²⁺ homeostasis usually lead to a plethora of diseases and pathogenic states, including cancer, heart failure, diabetes, and neurodegenerative disease. In this review, we examine recent discoveries in the highly localized nature of Ca²⁺-dependent signal transduction and its roles in cell fate, inflammasome activation, and synaptic transmission.

Calcium levels on admission and before discharge are associated with mortality risk in hospitalized patients

AIM

Investigate the association of calcium levels on admission and change in levels during hospitalization with hospitalization outcomes.

METHODS

Historical prospective data of patients hospitalized to units of internal medicine between 2011 and 2013. Albumin-corrected-calcium levels were classified to marked hypocalcemia (<7.5 mg/dL), mild hypocalcemia (7.5-8.5 mg/dL), normal calcium (8.5-10.5 mg/dL), mild hypercalcemia (10.5-11.5 mg/dL), marked hypercalcemia (>11.5 mg/dL). Main outcomes were length-of-hospitalization, in-hospital and long-term mortality.

RESULTS

Cohort included 30,813 patients (mean age 67 ± 18 years, 51% male). Follow-up (median ± standard deviation) was 1668 ± 325 days. Most patients had normal calcium on admission (93%), 3% had hypocalcemia, 3% had hypercalcemia. Common causes for marked hypercalcemia were malignancy (56%) and hyperparathyroidism (22%). Last calcium levels before discharge or death were normal in 94%, with similar rates of hypercalcemia or hypocalcemia (3% each). Compared to in-hospital mortality with normal calcium on admission (6%), mortality was higher with mild (8%) and marked hypocalcemia (11%), and highest with mild (18%) and marked hypercalcemia (22%). Mortality rate at the end of follow-up was 48% with normal calcium or mild hypocalcemia, 51% with marked hypocalcemia, 68 and 79% with mild and marked hypercalcemia, respectively. Patients with normal calcium on admission and before discharge had the best prognosis. Hypercalcemia on admission or before discharge was associated with a 70% mortality risk at the end of follow-up. Normalization of admission hypercalcemia had no effect on long-term mortality risk.

CONCLUSIONS

Abnormal calcium on admission is associated with increased short-term and long-term mortality. The excess mortality risk is higher with hypercalcemia than hypocalcemia. Calcium normalization before discharge had no effect on mortality.

Association of Serum Calcium Levels with Infarct Size in Acute Ischemic Stroke: Observations from Northeast India

BACKGROUND

Calcium is known to be major mediator in ischemic neuronal cell death. Recent studies have shown that elevated serum calcium levels at admission in patients with stroke have been associated with less severe clinical deficits and with better outcomes.

AIM

The aim of this to determine the correlation between serum calcium (total, corrected, and ionized) and infarct size (IS) in patients with acute ischemic stroke.

MATERIALS AND METHODS

Data were collected from 61 patients presenting with acute ischemic stroke from May 2015 to April 2016 at a tertiary care institute in Northeast India. Only patients aged ≥40 years and diagnosed as having acute ischemic cerebrovascular stroke with clinical examination and confirmed by a computed tomography scan were included in the study. Serum calcium levels (total, albumin corrected, and ionized) were collapsed into quartiles, and these quartile versions were used for calculating correlation. Pearson's correlation coefficient was used for comparing calcium levels with IS.

RESULTS

Total calcium, albumin-corrected calcium, and ionized calcium had a statistically significant negative correlation with IS with r = -0.578, -0.5396, and -0.5335, respectively. Total and ionized calcium showed a significant negative correlation with IS across all four quartiles. Albumin-corrected calcium levels showed a significant negative correlation with IS only across the lowest and highest quartiles.

CONCLUSION

The findings in our study suggest that serum calcium can be used as a prognostic indicator in ischemic stroke as its levels directly correlates with the IS.

Calcium supplementation and risk of dementia in women with cerebrovascular disease

OBJECTIVE

To determine whether calcium supplementation is associated with the development of dementia in women after a 5-year follow-up.

METHODS

This was a longitudinal population-based study. The sample was derived from the Prospective Population Study of Women and H70 Birth Cohort Study in Gothenburg, Sweden, and included 700 dementia-free women aged 70-92 years. At baseline in 2000-2001, and at follow-up in 2005-2006, the women underwent comprehensive neuropsychiatric and somatic examinations. A CT scan was performed in 447 participants at baseline. Information on the use and dosage of calcium supplements was collected. Dementia was diagnosed according to DSM-III-R criteria.

RESULTS

Women treated with calcium supplements (n = 98) were at a higher risk of developing dementia (odds ratio [OR] 2.10, 95% confidence interval [CI] 1.01-4.37, p = 0.046) and the subtype stroke-related dementia (vascular dementia and mixed dementia) (OR 4.40, 95% CI 1.54-12.61, p = 0.006) than women not given supplementation (n = 602). In stratified analyses, calcium supplementation was associated with the development of dementia in groups with a history of stroke (OR 6.77, 95% CI 1.36-33.75, p = 0.020) or presence of white matter lesions (OR 2.99, 95% CI 1.28-6.96, p = 0.011), but not in groups without these conditions.

CONCLUSIONS

Calcium supplementation may increase the risk of developing dementia in elderly women with cerebrovascular disease. Because our sample was relatively small and the study was observational, these findings need to be confirmed.

Use of Tethered Enzymes as a Platform Technology for Rapid Analyte Detection

BACKGROUND

Rapid diagnosis for time-sensitive illnesses such as stroke, cardiac arrest, and septic shock is essential for successful treatment. Much attention has therefore focused on new strategies for rapid and objective diagnosis, such as Point-of-Care Tests (PoCT) for blood biomarkers. Here we use a biomimicry-based approach to demonstrate a new diagnostic platform, based on enzymes tethered to nanoparticles (NPs). As proof of principle, we use oriented immobilization of pyruvate kinase (PK) and luciferase (Luc) on silica NPs to achieve rapid and sensitive detection of neuron-specific enolase (NSE), a clinically relevant biomarker for multiple diseases ranging from acute brain injuries to lung cancer. We hypothesize that an approach capitalizing on the speed and catalytic nature of enzymatic reactions would enable fast and sensitive biomarker detection, suitable for PoCT devices.

METHODS AND FINDINGS

We performed in-vitro, animal model, and human subject studies. First, the efficiency of coupled enzyme activities when tethered to NPs versus when in solution was tested, demonstrating a highly sensitive and rapid detection of physiological and pathological concentrations of NSE. Next, in rat stroke models the enzyme-based assay was able in minutes to show a statistically significant increase in NSE levels in samples taken 1 hour before and 0, 1, 3 and 6 hours after occlusion of the distal middle cerebral artery. Finally, using the tethered enzyme assay for detection of NSE in samples from 20 geriatric human patients, we show that our data match well (r = 0.815) with the current gold standard for biomarker detection, ELISA-with a major difference being that we achieve detection in 10 minutes as opposed to the several hours required for traditional ELISA.

CONCLUSIONS

Oriented enzyme immobilization conferred more efficient coupled activity, and thus higher assay sensitivity, than non-tethered enzymes. Together, our findings provide proof of concept for using oriented immobilization of active enzymes on NPs as the basis for a highly rapid and sensitive biomarker detection platform. This addresses a key challenge in developing a PoCT platform for time sensitive and difficult to diagnose pathologies.