The effect of gingko biloba on hearing in mice with noise-induced temporary threshold shift

Does glutaric aciduria type 1 affect hearing function?

This study aimed to evaluate audiological findings among patients with glutaric aciduria type 1 (GA-1). We used a large test battery for the audiological evaluation of 17 individuals with GA-1 (the study group) and 20 healthy individuals (the control group). Conventional audiometry (0.125-8 kHz), distortion product otoacoustic emissions (DPOAEs) (1, 1.5, 2, 3, 4, 6, and 8 kHz), contralateral suppression of otoacoustic emissions, and auditory brainstem response (ABR) ( 30, 50, 70 and 90 dB nHL) were measured for all participants (n = 37). Mild sensorineural hearing loss was found in 77.47% (n = 13) of the patients with GA-1, and normal hearing thresholds were seen in 23.53% (n = 4). There were three asymptomatic patients at the time of diagnosis [two developed mild mental motor retardation (MMR) and one developed severe MMR during the follow-up], one with a normal hearing threshold and two with mild hearing loss), and 14 symptomatic patients (three with normal hearing thresholds and 11 with mild hearing loss). Seven of the symptomatic patients diagnosed following an encephalopathic crisis required intensive care and showed significantly worse hearing thresholds than those without symptoms [20.86 ± 4.47 vs. 15.44 ± 3.96 decibel hearing level (dB HL), p = 0.039*], while five had mild-to-moderate hearing loss. Acute encephalopathic crisis had a negative effect on hearing function in the symptomatic patients. The emission and contralateral suppression amplitude values of the study group were significantly lower compared to the control group (p < 0.05). The I-V interpeak latency and absolute latencies of ABR waves I, III, and V of the study group were observed to be significantly prolonged and morphologically distorted compared to those of the control group (p < 0.05). Five patients had MMR, and three had moderate MMR; all eight had mild-to-moderate hearing loss. In addition, of the eight patients with mild MMR, four had mild hearing loss. In particular, the morphological findings of ABR waves were significantly worse in the patients with severe and moderate MMR (p < 0.05). There was a significant correlation between a macrocephaly history (12 patients) and hearing loss (p = 0.041*). Magnetic resonance imaging findings were evaluated in all the 17 patients with GA-1, and typical fronto-temporal atrophy and sylvian fissure enlargement were observed. Our findings support that GA-1 is associated with auditory impairment, primarily in symptomatic patients. Adequate audiological test battery evaluation is essential in this context, particularly for symptomatic patients with a history of encephalopathic crises.

Angelica archangelica and Ginkgo biloba Extracts Recover Functional Blood Hemoglobin Derivatives in Rabbits Exposed to High Altitude

BACKGROUND

Shortage of oxygen is a common condition for residents of high-altitude (HA) areas. In mammals, hemoglobin (Hb) has four derivatives: oxyhemoglobin (Hb-O2)‎, carboxyhemoglobin (Hb-CO), sulfhemoglobin (Hb-S), and methemoglobin (Met-Hb). In HA areas, aberrant physiological performance of blood hemoglobin is well-established.

OBJECTIVE

The study aimed to investigate the influence of 30 days of HA residence on rabbits' total Hb, Hb derivatives, Hb autooxidation rate, and antioxidant enzymes in comparison to low-altitude control rabbits. Further, the study aimed to investigate the effect of antioxidant-rich Angelica archangelica and/or Ginkgo biloba extracts on the same parameters in HA-resident rabbits.

METHODS

Rabbits subjected to 30 days of HA residence were compared to low-altitude control rabbits. HA-residence rabbits were then orally administered 0.11 g/kg b.wt. of Angelica archangelica and/or Ginkgo biloba extract for 14 days. Hb derivatives and Hb autooxidation rate were measured spectrophotometrically. Antioxidant enzymes were estimated using specialized kits.

RESULTS

Compared to low-altitude rabbits, 30-day HA-residence rabbits showed a noticeable increase (p<0.05) in Hb-O2‎ and Hb-CO concentration. In addition, Met-Hb concentration, autooxidation rate of Hb molecules, and activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) exhibited a remarkable increase in HA-residence rabbits (p<0.01), reflective of rapid ROS generation. In HA-residence rabbits, both individual and combined treatment with antioxidant-rich extracts for 14 days resulted in recovery to near-normal functional levels of Hb-O2‎ and Met-Hb, Hb autooxidation rate, and activities of SOD and GPx, while only combined treatment led to Hb-O2 recovery.

CONCLUSION

The findings suggest that functional Hb levels may be recovered by oral administration of A. archangelica, G. biloba, or combined treatments. In conclusion, oxidative stress due to living in HA areas may be avoided by supplementation with natural antioxidants.

Pharmacologic treatments in preclinical tinnitus models with special focus on Ginkgo biloba leaf extract EGb 761®

Tinnitus is defined as the perception of sound in the absence of external acoustic stimuli. Frequent comorbidities or associated factors are depression, anxiety, concentration problems, insomnia, resignation, helplessness, headache, bruxism, or social isolation, just to name a few. Although many therapeutic approaches have already been tested with varying success, there still is no cure available for tinnitus. The search for an effective treatment has been hampered by the fact that the mechanisms of tinnitus development are still not fully understood, although several models are available and discussed in this review. Our review will give a brief overview about preclinical models, presenting the heterogeneity of tinnitus sub-types depending on the different inner ear and brain structures involved in tinnitus etiology and pathogenesis. Based on these models we introduce the different target structures and transmitter systems implicated in tinnitus development and provide an extensive overview on preclinical drug-based therapeutic approaches that have been explored in various animal models. As the special extract from Ginkgo biloba leaves EGb 761® has been the most widely tested drug in both non-clinical tinnitus models as well as in clinical trials, a special focus will be given to EGb 761®. The efficacy of terpene lactones, flavone glycosides and proanthocyanidines with their distinct contribution to the overall efficacy profile of the multi-constituent drug EGb 761® will be discussed.