Antifungal Mechanism of Action of Lauryl Betaine Against Skin-Associated Fungus Malassezia restricta

Betaine derivatives are considered major ingredients of shampoos and are commonly used as antistatic and viscosity-increasing agents. Several studies have also suggested that betaine derivatives can be used as antimicrobial agents. However, the antifungal activity and mechanism of action of betaine derivatives have not yet been fully understood. In this study, we investigated the antifungal activity of six betaine derivatives against Malassezia restricta, which is the most frequently isolated fungus from the human skin and is implicated in the development of dandruff. We found that, among the six betaine derivatives, lauryl betaine showed the most potent antifungal activity. The mechanism of action of lauryl betaine was studied mainly using another phylogenetically close model fungal organism, Cryptococcus neoformans, because of a lack of available genetic manipulation and functional genomics tools for M. restricta. Our genome-wide reverse genetic screening method using the C. neoformans gene deletion mutant library showed that the mutants with mutations in genes for cell membrane synthesis and integrity, particularly ergosterol synthesis, are highly sensitive to lauryl betaine. Furthermore, transcriptome changes in both C. neoformans and M. restricta cells grown in the presence of lauryl betaine were analyzed and the results indicated that the compound mainly affected cell membrane synthesis, particularly ergosterol synthesis. Overall, our data demonstrated that lauryl betaine influences ergosterol synthesis in C. neoformans and that the compound exerts a similar mechanism of action on M. restricta.

The Characteristics and the Changes of Tinnitus according to the Recovery of Hearing Loss in the Patients with Sudden Hearing Loss / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Because tinnitus can be generated from the damaged cochlear hair cells, patients with sudden sensorineural hearing loss frequently complain their tinnitus as an important symptom. We prospectively designed this study to understand the clinical characteristics of tinnitus in patients with sudden sensorineural hearing loss. MATERIALS AND METHOD: Thirty-seven patients with sudden sensorineural hearing loss who performed an audiologic study and questionnare of tinnitus before and immediately after the combination therapy for hearing loss were included. Their clinical and audiologic data were prospectively entered into a comprehensive data base to analyze the clinical characteristics of tinnitus. RESULTS: Most of the patients with sudden sensorineural hearing loss showed abrupt and concomitant onset of tinnitus in the same ear of hearing loss. The characteristics of tinnitus were changed according to the degree of hearing recovery of sudden hearing loss. CONCLUSION: Improvement of tinnitus in the patients with sudden sensorineural hearing loss may be closely related to the degree of hearing recovery. Understanding the characteristics of tinnitus in patients with sudden sensorineural hearing loss might be helpful in counselling them during the treatment period of hearing loss.