In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Q: Context: Myocardial infarction (MI) induces neural remodelling of the left stellate ganglion (LSG), which may contribute to ischaemia-induced arrhythmias. The neural chemorepellent Semaphorin 3a (Sema3a) has been identified as a negative regulator of sympathetic innervation in the LSG and heart. We previously reported that overexpression of Sema3a in the border zone could reduce the arrhythmogenic effects of cardiac sympathetic hyperinnervation post-MI. This study investigated whether Sema3a overexpression within the LSG confers an antiarrhythmic effect after MI through decreasing extra- and intra-cardiac neural remodelling.', 'Sprague-Dawley rats were subjected to MI, and randomly allocated to intra-LSG microinjection of either phosphate-buffered saline (PBS), adenovirus encoding green fluorescent protein (AdGFP), or adenovirus encoding Sema3a (AdSema3a). Sham-operated rats served as controls. Two weeks after infarction, MI-induced nerve sprouting and sympathetic hyperinnervation in the LSG and myocardium were significantly attenuated by intra-LSG injection with AdSema3a, as assessed by immunohistochemistry and western blot analysis of growth-associated protein 43 and tyrosine hydroxylase. This was also confirmed by sympathetic nerve function changes assessed by cardiac norepinephrine content. Additionally, intra-LSG injection with AdSema3a alleviated MI-induced accumulation of dephosphorylated connexin 43 in the infarct border zone. Furthermore, Sema3a overexpression in the LSG reduced the incidence of inducible ventricular tachyarrhythmia by programmed electrical stimulation post-MI, and arrhythmia scores were significantly lower in the AdSema3a group than in the PBS and AdGFP groups.\Question: Does semaphorin 3a transfection into the left stellate ganglion reduce susceptibility to ventricular arrhythmias after myocardial infarction in rats?

A: Semaphorin 3a overexpression in the LSG ameliorates the inducibility of ventricular arrhythmias after MI, mainly through attenuation of neural remodelling within the cardiac-neuraxis.
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Q: Context: Abnormalities of serum sodium are common after subarachnoid hemorrhage (SAH) and have been linked to poor outcome. This study analyzed whether abnormal serum sodium levels are associated with cardiac outcomes and mortality after subarachnoid hemorrhage (SAH).', "In a prospective cohort study of SAH patients, the primary predictor variable was subjects' sodium level. Hypernatremia was defined as sodium >143 mmol/L and hyponatremia was <133 mmol/L. Cardiac troponin I (cTi) was measured and echocardiography was performed on three study days. Dichotomous outcome variables were cTi > 1.0 microg/L, left-ventricular ejection fraction (LVEF) <50%, presence (vs absence) of regional wall motion abnormalities (RWMA) of the LV, pulmonary edema, and death. Additional analyses studied the degree of hypernatremia and sodium supplementation, and the temporal relationship between hypernatremia and cardiac outcomes.", 'The study included 214 subjects. Forty-eight subjects (22%) were hypernatremic on at least one study day, and 45 (21%) were hyponatremic. After multivariate adjustment, hypernatremia was an independent predictor of LVEF <50% (OR 4.7, CI 1.3-16.2, p = 0.015), elevated cTi (OR 3.7, CI 1.2-11.9, p = 0.028), and pulmonary edema (OR 4.1 CI 1.4-1.5, p = 0.008). It was not, however a statistically significant predictor of mortality (p = 0.075).\Question: Does hypernatremia predict adverse cardiovascular and neurological outcomes after SAH?

A: In the acute period after SAH, hypernatremia is associated with adverse cardiac outcomes and death. SAH patients with hypernatremia should be monitored for evidence of cardiac dysfunction.
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Q: Context: We performed diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS) studies in a group of patients with subacute sclerosing panencephalitis (SSPE) in order to estimate the pathologic process underlying the phenotypic variability.', 'Patients with SSPE who had MRI including DTI and MRS examinations were evaluated according to their clinical status as determined by the SSPE Scoring System and their mental age as determined by tests appropriate for age and developmental level. Comparisons of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values and metabolite ratios of frontal periventricular white matter, parieto-occipital periventricular white matter, and globus pallidus in both hemispheres were made between control and SSPE groups, and between SSPE subgroups.', 'Control (n = 18) and SSPE (n = 39) groups differed in all DTI and MRS parameters except FA, choline (Cho), and Cho/creatine (Cr). SSPE cases had higher ADC and lower N-acetylaspartate (NAA), NAA/Cho, and NAA/Cr in all regions of interest, suggesting cell loss. Disease progression rate and neurologic deficit appeared to be associated with the degree of ADC elevation and NAA reduction: the group with severe global deterioration had the lowest NAA (230.75 ± 197.97 in forceps minor), and rapid progression was associated with acute reduction in NAA.\Question: Is neuronal loss an early component of subacute sclerosing panencephalitis?

A:
The combination of MRS and diffusion MRI findings suggests neuronal loss can be a primary target in rapidly or subacutely progressing SSPE, and preservation or regeneration of axonal structure may be beneficial in chronic cases.
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