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.


[Q]: Context: To investigate the role of the anti-cellular immune response in the protection of rhesus macaques against infection with the simian immunodeficiency virus SIVmac. To determine the biological differences between SIV challenge stocks grown either on human T-cell lines or on monkey peripheral blood mononuclear cells (MPBMC).', 'A protective SIVmac split vaccine was administered to rhesus macaques and their anti-, B- and T-cell response monitored. Vaccinees and controls were challenged with SIVmac grown either on human or on monkey cells. The in vivo replication rate of, and the immune response to, the two viruses was compared.', 'Five rhesus macaques were immunized with a total of 2 mg each of purified SIVmac251/32H grown on the human C8166 T-cell line. The antibody and proliferative T-cell responses were evaluated by enzyme-linked immunosorbent assay and T-cell proliferation assay, respectively. Four protected animals and four controls were reboosted and challenged with MPBMC-grown SIVmac251 (SIVmac251/MPBMC). Cell-free virus load was determined by titration of plasma for SIV infectivity on C8166 cells and antigen with a core antigen capture assay.', 'Protection from virus challenge with C8166-grown SIVmac251/32H or SIVmac251/MPBMC did not correlate with anti-cellular antibodies or proliferative T-cell reactivities. Control animals infected with SIVmac251/MPBMC showed high persistent antigenaemia and high plasma virus titres. Both were absent in controls infected with complement C8166-grown SIVmac251/32H. Whereas the latter always seroconverted against the full panel of viral polypeptides, SIVmac251/MPBMC-infected animals showed a drastically decreased antibody response.\Question: Does protection of monkeys by a split vaccine against SIVmac depend upon biological properties of the challenge virus?
[A]: Neither the antibody nor the proliferative T-cell response to SIVmac correlates with protection from virus challenge. In contrast to SIVmac251/32H grown on C8166 cells, the MPBMC-grown challenge virus SIVmac251 appears to belong to the 'rapid-high' phenotype, possibly explaining the lack of protection against this SIV.


[Q]: Context: The safety and efficacy of prescribing a single maternal course of corticosteroid during pregnancy has been documented in human trials. However, the current trend is to prescribe repeated courses of corticosteroid. We investigated an aspect of the safety of this practice in an animal model.', 'Date-mated ewes received saline, single or four corticosteroid injections between days 104 and 124 of gestation (term = 150). Lambs were delivered on day 125 or 145 by caesarian section after spinal anaesthesia. Eye diameters were measured and semi-thin toluidine-blue-stained transverse sections of retinae were analysed using an Optimus Image Analysis program.', 'At 125 days, retinal measures in the ventral periphery and area centralis were significantly thinner than control (p = 0.0001). At 145 days, total eye size was significantly reduced compared with control (p = 0.03), and retinal measures in the ventral periphery (p = 0.0001), but not the area centralis (p = 0.19), remained significantly different from control.\Question: Is retinal maturation delayed by repeated , but not single , maternal injections of betamethasone in sheep?
[A]:
Repeated maternal administration of corticosteroid may affect retinal maturation in the fetus.