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Neuroimmunol Neuroinflammation 2019;6:15 I http://dx.doi.org/10.20517/2347-8659.2019.019 Page 19 of 24

Methods: We included patients who developed FS after six years of age and presented to our outpatient
clinic between January 2011 and June 2017. Clinical data were obtained through chart reviews and
phone call interviews. We used logistic regression analysis to analyze the risk factors associated with the
occurrence of subsequent unprovoked seizure.

Results: Of the 895 patients, 83 developed FS after six years of age. Among these 83, three patients were
prescribed antiepileptic drugs before the onset of the unprovoked seizure and four patients developed an
unprovoked seizure before six years of age. Thus, overall, 76 patients were included in the study. Fifty-one
patients developed first FS before six years of age. In the remaining patients, the first FS developed after six
years of age. The mean observational period since the last outpatient follow-up visit was 3.2 years (median
3.04 years, range: 1.42-4.71 years). Among them, 21% developed an unprovoked seizure. Logistic regression
analysis showed that electroencephalographic (EEG) abnormalities serve as an independent risk factor for
a subsequent unprovoked seizure.

Conclusion: EEG is the proper diagnostic tool to predict the risk of a subsequent unprovoked seizure in
patients with FS after six years of age.

27. Comparative effects of hydrogen sulfide-releasing compounds on [3H]D-aspartate release

from bovine isolated retinae

Catherine A. Opere

School of Pharmacy and Health professions, Department of Pharmacy Sciences, Creighton University, Omaha,
NE, USA

Previously known as an industrial toxicant, hydrogen sulfide (H2S) has evolved into a signaling
gasotransmitter that possess physiological roles in the central nervous, cardiovascular and the immune
systems (Kimura Molecules 2014;19:16146). It is endogenously derived from L-cysteine and D-cysteine
by cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE) enzymes, with some contribution from
cysteine aminotransferase and D-aminotransferase in combination with 3-mercaptosulfurtransferase using
L-cysteine or homocysteine as substrates (Abe & Kimura. J Neurosci 1996;16:1066; Nagai Y et al. FASEB J
2004;18:557). In ocular tissues, a deficiency of CBS due to a mutation in the gene encoding the enzyme is
associated with several eye disorders such as glaucoma, cataracts and retinal detachment [Kraus JP, Kozich
V. In Carmel & Jacobsen DW (eds) Homocysteine in health and disease. Cambridge University Press;
2001. p. 223]. Furthermore, H2S has been shown to exert pharmacological effects on mammalian ocular
tissues from both anterior and posterior segments in vitro and in vivo (Ohia et al. J Ocul Pharmacol Ther
2018;34:61). In the present study, we used the Superfusion Method to (1) compare the pharmacological
+
actions GYY 4137, a slow-releasing H2S donor to that of L-cysteine, a substrate for H2S biosynthesis on K -
evoked [3H]D-aspartate release, and (2) examine the role of KATP channels and nitric oxide (NO) in the
responses elicited by these compounds on neurotransmitter release in isolated bovine retinae. GYY 4137
(10 nM - 10 µM), L-cysteine (100 nM - 10 µM) and its prodrug, N-acetyl cysteine (10 µM -1 mM)
+
attenuated K -evoked [3H]D-aspartate release in a concentration-dependent manner from isolated
bovine retinae without affecting basal tritium efflux. The rank order of activity observed at an equimolar
concentration of 10 µM was: L-cysteine > GYY 4137 > N-acetyl cysteine. Interestingly, the dual inhibitor
of the biosynthetic enzymes for H2S, CBS and CSE, amino-oxyacetic acid (3 mM) reversed the inhibitory