The present study explored the therapeutic potential of hydrogen sulfide (H 2 S) in restoring aging-induced loss of cardioprotective effect of remote ischemic preconditioning (RIPC) along with the involvement of signaling pathways. The left hind limb was subjected to four short cycles of ischemia and reperfusion (IR) in young and aged male rats to induce RIPC. The hearts were subjected to IR injury on the Langendorff apparatus after 24 h of RIPC. The measurement of lactate dehydrogenase, creatine kinase and cardiac troponin served to assess the myocardial injury. The levels of H 2 S, cystathionine -synthase (CBS), cystathionine -lyase (CSE), nuclear factor erythroid 2-related factor 2 (Nrf2), and hypoxia-inducible factor (HIF-1) were also measured. There was a decrease in cardioprotection in RIPC-subjected old rats in comparison to young rats along with a reduction in the myocardial levels of H 2 S, CBS, CSE, HIF-1, and nuclear: cytoplasmic Nrf2 ratio. Supplementation with sodium hydrogen sulfide (NaHS, an H 2 S donor) and l-cysteine (H 2 S precursor) restored the cardioprotective actions of RIPC in old hearts. It increased the levels of H 2 S, HIF-1, and Nrf2 ratio without affecting CBS and CSE. YC-1 (HIF-1 antagonist) abolished the effects of NaHS and l-cysteine in RIPC-subjected old rats by decreasing the Nrf2 ratio and HIF-1 levels, without altering H 2 S.The late phase of cardioprotection of RIPC involves an increase in the activity of H 2 S biosynthetic enzymes, which increases the levels of H 2 S to upregulate HIF-1 and Nrf2. H 2 S has the potential to restore aging-induced loss of cardioprotective effects of RIPC by upregulating HIF-1/Nrf2 signaling.

In this study, we aimed to study the pattern visual evoked potentials (P-VEPs) in two eyes with varying visual acuity in one eye and to provide an objective estimation of visual acuity by comparing P-VEPs in one and two eyes. Thirty subjects were chosen, who had one eye with an acuity of 5.0, 4.85, 4.6, 4.0, or scieropia and obstructed vision and the other eye with an acuity of 5.0, respectively. P-VEPs were detected under the large grating stimuli at 3×4 spatial frequency, moderate grating stimuli (12×16 spatial frequency) and small grating stimuli (48×64 spatial frequency). Under large grating stimuli, there was no significant difference in P100 peak latency between the groups, nor was there a significant difference between the amplitude of two eyes and the amplitude of one normal-vision eye. Under moderate and small grating stimuli, there was a significant difference in P100 peak latency between the group with both eyes having an acuity of 5.0 and the group with visual acuity below 4.0 in one eye. There was a significant difference in P100 amplitude between the group with visual acuity of 5.0 in both eyes and the group with one normal-vision eye. There was no significant difference in the amplitude of two eyes and the amplitude of one normal-vision eye between any other two groups. In forensic identification, characteristics and variability of P-VEPs in one and two eyes can be used to identify malingering or decline in visual acuity.

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