Reference sound pressure level for Korean speech audiometry

The validity of an isiZulu speech reception threshold test for use with adult isiZulu speakers

Background

This study continued the development of an isiZulu speech reception threshold (zSRT) test for use with first language, adult speakers of isiZulu.

Objectives

The objective of this study was to determine the convergent and concurrent validity of the zSRT test.

Methods

One hundred adult isiZulu first-language speakers with normal hearing and 76 first-language, adult isiZulu speakers with conductive or sensorineural hearing losses ranging from mild to severe were assessed on pure tone audiometry and a newly developed isiZulu SRT test. Convergent validity was established through agreement of the zSRT scores with pure tone average (PTA) scores. Concurrent validity was assessed by examining the steepness of the psychometric curve for each word in the zSRT test for each type and degree of hearing loss.

Results

Intraclass correlation coefficient analyses showed zSRT scores were in substantial to very high agreement with PTA scores for the normal hearing and hearing loss groups (NH – right ear ICC consistency = 0.78, left ear ICC = 0.67; HL – right ear ICC consistency = 0.97, left ear ICC consistency = 0.95). The mean psychometric slope (%/dB) at 50% correct perception for all words in the zSRT test was 4.92%/dB for the mild conductive hearing loss group, 5.26%/dB for the moderate conductive hearing loss group, 2.85%/dB for the moderately severe sensorineural hearing loss group and 2.47%/dB for the severe sensorineural hearing loss group. These slopes were appropriate for the degree of hearing loss observed in each group.

Conclusion

The zSRT test showed convergent and concurrent validity for assessing SRT in first language, adult speakers of isiZulu.

Icariside II, a PDE5 Inhibitor, Suppresses Oxygen-Glucose Deprivation/Reperfusion-Induced Primary Hippocampal Neuronal Death Through Activating the PKG/CREB/BDNF/TrkB Signaling Pathway

Background

Ischemic stroke remains the leading cause of death and adult disability. Cerebral ischemic/reperfusion (I/R) injury is caused by ischemic stroke thereafter aggravates overwhelming neuronal apoptosis and even the death of neurons. Of note, hippocampus is more susceptive to cerebral I/R injury than the other brain region. This study was designed to explore the effects and mechanism of icariside II (ICS II), a pharmacologically active compound exists in herbal Epimedii with previous study-proved as a phosphodiesterase 5 (PDE5) inhibitor, on the oxygen glucose deprivation/reoxygenation (OGD/R)-induced primary hippocampal neurons injury.

Methods

Effects of ICS II on primary hippocampal neuronal impairment and apoptosis induced by OGD/R were examined by MTT, lactate dehydrogenase (LDH) release, TUNEL staining, and flow cytometry, respectively. Activation of memory-related signaling pathways was measured using Western blot analysis. The direct interaction between ICS II and PDE5 was further evaluated by molecular docking.

Results

ICS II (12.5, 25, 50 μM) markedly abrogated OGD/R-induced hippocampal neuronal death as suggested by the increase in neurons viability and the decrease in cellular LDH release. Furthermore, ICS II not only effectively decreased the protein expression and activity of PDE5, restored the 3′5′-cyclic guanosine monophosphate (cGMP) level and its downstream target protein kinase G (PKG) activity but also increased the phosphorylation of cAMP response element binding protein (CREB) level, expressions of brain derived neurotrophic factor (BDNF), and tyrosine protein kinase B (TrkB). Mechanistically, the inhibitory effects of ICS II were abrogated by Rp-8-Br-cGMP (a PKG inhibitor) or ANA-12 (a TrkB inhibitor), which further confirmed that the favorable effects of ICS II were attributed to its activation of the PKG/CREB/BDNF signaling pathways. Intriguingly, ICS II might effectively bind and inhibited PDE5 activity as demonstrated by relatively high binding scores (−6.52 kcal/mol).

Conclusions

ICS II significantly rescues OGD/R-induced hippocampal neuronal injury. The mechanism is, at least partly, due to inhibition of PDE5 and activation of PKG/CREB/BDNF/TrkB signaling pathway. Hence it is thought that ICS II might be a potential naturally PDE5 inhibitor to combat cerebral I/R injury.