Electrical Stimulation of the Vagus Nerve Dermatome in the External Ear is Protective in Rat Cerebral Ischemia

Background Although cervical vagus nerve stimulation is effective for reducing infarct volume in rats, it is not feasible for acute human stroke as it requires surgical incision of the neck. We hypothesized that stimulation of the dermatome in the external ear innervated by the vagus nerve (auricular vagus nerve stimulation; aVNS) reduces infarct volume after transient focal ischemia in rats. Methods Animals were randomized to active aVNS or sham stimulation. For aVNS, electrical stimulation of the left cavum concha (1 hour duration) using percutaneous needles was initiated 30 min after induction of ischemia. Behavioral and tissue outcome were measured 24 hours after induction of ischemia. In a separate experimental dataset, c-Fos immunohistochemistry was performed to identify the brain regions activated after the stimulation. Results Stimulation of the left cavum concha resulted in bilateral c-Fos staining in the nuclei tractus solitarii and the loci coerulei in all animals. There was no c-Fos staining in any part of the brainstem in sham control animals. The mean infarct volume (SD) as calculated by indirect method was 44.20 ± 7.58% in controls and 31.65 ± 9.67% in treated animals (p<0.0001). The effect of aVNS on tissue outcome was associated with better neurological scores at 24 hours after ischemia (p<0.0001). Conclusions Electric stimulation of the vagus nerve dermatome in the external ear activates brainstem afferent vagal nuclei and reduces infarct volume in rats. This finding has potential to facilitate the development of treatments that leverage the brain’s endogenous neuroprotective pathways at the setting of acute ischemic stroke

Determining Students’ Conceptual Understanding Level of Thermodynamics

Science students find heat, temperature, enthalpy and energy in chemical reactions to be some of the most difficult subjects. It is crucial to define their conceptual understanding level in these subjects so that educators can build upon this knowledge and introduce new thermodynamics concepts. This paper reports conceptual understanding levels of high school students of common thermodynamics subjects such as heat, temperature, enthalpy and energy changes in chemical reactions. The sample of the study was composed of 418 randomly selected students from 11 different high schools. A cross sectional survey model was employed in this study. Data were collected through the Conceptual Understanding Test (CUT), which consists of 16 questions. Cronbach's alpha reliability coefficient for the test was 0.72. Besides, interviews were conducted with 10 students to get qualitative data about their beliefs on the subject. The results of the study indicated that students’ level of conceptual understanding in thermodynamics concepts is very low. It was observed to be especially low for the concepts of (1) relationship between energy, enthalpy and bonds in chemical reactions, (2) energy and catalysts in chemical reactions, (3) changes in heat, temperature and enthalpy during change of state, and (4) the relationship between heat, temperature, mass and specific heat. Most of the students in this study do not fully understand common thermodynamics concepts although they have been studying these topics since primary school

Spontaneous pneumomediastinum incidence and clinical features in non-intubated patients with COVID-19

OBJECTIVES: To evaluate the presentation characteristics and disease course of seven patients with COVID-19 who spontaneously developed pneumomediastinum without a history of mechanical ventilation.METHODS: A total of seven non-intubated patients with COVID-19, of age ranging from 18-67 years, who developed spontaneous pneumomediastinum between 01 April and 01 October 2020 were included in the study. Patients’ demographic data, clinical variables, and laboratory values were examined. Spontaneous pneumomediastinum was evaluated using posteroanterior chest radiography and thorax computed tomography.RESULTS: During the research period, 38,492 patients reported to the emergency department of our hospital with COVID-19 symptoms. Of these, spontaneous pneumomediastinum was detected in seven patients who had no previous history of intubation. Chronic obstructive pulmonary disease (2/7) and asthma bronchiale (2/7) were determined as the most common causes of comorbidity.CONCLUSION: In our study, the frequency of spontaneous pneumomediastinum developing without pneumothorax was found to be high in non-intubated patients. Whether this is related to the nature of the disease or it is a result of the increase in cases diagnosed incidentally owing to the increasing use of low-dose computed tomography should be explored in further studies

Brain imaging in patients with transient ischemic attack: a comparison of computed tomography and magnetic resonance imaging

Background: Brain imaging in stroke aims at the detection of the relevant ischemic tissue pathology. Cranial computed tomography (CT) is frequently used in patients with transient ischemic attack (TIA) but no data is available on how it directly compares to magnetic resonance imaging (MRI). Methods: We compared detection of acute ischemic lesions on CT and MRI in 215 consecutive TIA patients who underwent brain imaging with either CT (n = 161) or MRI (n = 54). An MRI was performed within 24 h in all patients who had CT initially. Results: An initial assessment with CT revealed no acute pathology in 154 (95.7%) and possible acute infarction in 7 (4.3%) patients. The acute infarct on CT was confirmed by diffusion-weighted imaging (DWI) in only 2 cases (28.6%). DWI detected an acute infarct in 50 of the 154 patients with normal baseline CT (32.5%). Among 54 patients without baseline CT, DWI showed acute ischemic lesions in 19 (35.2%). The ischemic lesions had a median volume of 0.87 cm 3 (range: 0.08–15.61), and the lesion pattern provided clues to the underlying etiology in 13.7%. Conclusion: Acute MRI is advantageous over CT to confirm the probable ischemic nature and to identify the etiology in TIA patients

Evaluation of the Oxidative Effect of Long-Term Repetitive Hyperbaric Oxygen Exposures on Different Brain Regions of Rats

Hyperbaric oxygen (HBO2) exposure affects both oxidative and antioxidant systems. This effect is positively correlated with the exposure time and duration of the treatment. The present study aims enlightening the relation of HBO2 with oxidative/antioxidant systems when administered in a prolonged and repetitive manner in brain tissues of rats. Sixty rats were divided into 6 study (n = 8 for each) and 1 control (n = 12) group. Rats in the study groups were daily exposed 90-min HBO2 sessions at 2.8 ATA for 5, 10, 15, 20, 30 and 40 days. One day after the last session, animals were sacrificed; their whole brain tissue was harvested and dissected into three different regions as the outer grey matter (cortex), the inner white matter and cerebellum. Levels of lipid peroxidation and protein oxidation and activities of superoxide dismutase and glutathione peroxidase were measured in these tissues. Malondialdehyde, carbonylated protein and glutathione peroxidase levels were found to be insignificantly increased at different time-points in the cerebral cortex, inner white matter and cerebellum, respectively. These comparable results provide evidence for the safety of HBO treatments and/or successful adaptive mechanisms at least in the brain tissue of rats, even when administered for longer periods

Lower Hemoglobin Correlates with Larger Stroke Volumes in Acute Ischemic Stroke

www.karger.com/cee This is an Open Access article licensed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License (www.karger.com/OA-license), applicable to the online version of the article only. Distribution for non-commercial purposes only

Effect of Intensive Versus Standard Blood Pressure Control on Stroke Subtypes

In the SPRINT (Systolic Blood Pressure Intervention Trial), the number of strokes did not differ significantly by treatment group. However, stroke subtypes have heterogeneous causes that could respond differently to intensive blood pressure control. SPRINT participants (N=9361) were randomized to target systolic blood pressures of \u3c120 mm Hg (intensive treatment) compared with \u3c140 mm Hg (standard treatment). We compared incident hemorrhage, cardiac embolism, large- and small-vessel infarctions across treatment arms. Participants randomized to the intensive arm had mean systolic blood pressures of 121.4 mm Hg in the intensive arm (N=4678) and 136.2 mm Hg in the standard arm (N=4683) at one year. Sixty-nine strokes occurred in the intensive arm and 78 in the standard arm when SPRINT was stopped. The breakdown of stroke subtypes across treatment arms included hemorrhagic (intensive treatment, n=6, standard treatment, n=7) and ischemic stroke subtypes (large artery atherosclerosis: intensive treatment n=11, standard treatment, n=13; cardiac embolism: intensive treatment n=11, standard treatment n=15; small artery occlusion: intensive treatment n=8, standard treatment n=8; other ischemic stroke: intensive treatment n=3, standard treatment n=1). Fewer strokes occurred among participants without prior cardiovascular disease in the intensive (n=43) than the standard arm (n=61), but the difference did not reach predefined statistical significance level of 0.05 (P=0.09). The interaction between baseline cardiovascular risk factor status and treatment arm on stroke risk did not reach significance (P=0.05). Similar numbers of stroke subtypes occurred in the intensive BP control and standard control arms of SPRINT

Subtype Specificity of Genetic Loci Associated With Stroke in 16 664 Cases and 32 792 Controls

Background: Genome-wide association studies have identified multiple loci associated with stroke. However, the specific stroke subtypes affected, and whether loci influence both ischemic and hemorrhagic stroke, remains unknown. For loci associated with stroke, we aimed to infer the combination of stroke subtypes likely to be affected, and in doing so assess the extent to which such loci have homogeneous effects across stroke subtypes. Methods: We performed Bayesian multinomial regression in 16 664 stroke cases and 32 792 controls of European ancestry to determine the most likely combination of stroke subtypes affected for loci with published genome-wide stroke associations, using model selection. Cases were subtyped under 2 commonly used stroke classification systems, TOAST (Trial of Org 10172 Acute Stroke Treatment) and causative classification of stroke. All individuals had genotypes imputed to the Haplotype Reference Consortium 1.1 Panel. Results: Sixteen loci were considered for analysis. Seven loci influenced both hemorrhagic and ischemic stroke, 3 of which influenced ischemic and hemorrhagic subtypes under both TOAST and causative classification of stroke. Under causative classification of stroke, 4 loci influenced both small vessel stroke and intracerebral hemorrhage. An EDNRA locus demonstrated opposing effects on ischemic and hemorrhagic stroke. No loci were predicted to influence all stroke subtypes in the same direction, and only one locus (12q24) was predicted to influence all ischemic stroke subtypes. Conclusions: Heterogeneity in the influence of stroke-associated loci on stroke subtypes is pervasive, reflecting differing causal pathways. However, overlap exists between hemorrhagic and ischemic stroke, which may reflect shared pathobiology predisposing to small vessel arteriopathy. Stroke is a complex, heterogeneous disorder requiring tailored analytic strategies to decipher genetic mechanisms