Therapeutic Value of Ginkgo biloba Extract EGb 761® in an Animal Model (Meriones unguiculatus) for Noise Trauma Induced Hearing Loss and Tinnitus

Anthelmintic efficacy of an organic fraction from Guazuma ulmifolia leaves and evaluation of reactive oxidative stress on Haemonchus contortus

This study describes the anthelmintic efficacy of an organic fraction (EtOAc-F) from Guazuma ulmifolia leaves and the evaluation of its reactive oxidative stress on Haemonchus contortus. The first step was to assess the anthelmintic effect of EtOAc-F at 0.0, 3.5, 7.0 and 14 mg kg of body weight (BW) in gerbil's (Meriones unguiculatus) artificially infected with H. contortus infective larvae (L3). The second step was to evaluate the preliminary toxicity after oral administration of the EtOAc-F in gerbils. Finally, the third step was to determine the relative expression of biomarkers such as glutathione (GPx), catalase (CAT), and superoxide dismutase (SOD) against H. contortus L3 post-exposition to EtOAc-F. Additionally, the less-polar compounds of EtOAc-F were identified by gas mass spectrophotometry (GC-MS). The highest anthelmintic efficacy (97.34%) of the organic fraction was found in the gerbils treated with the 14 mg/kg of BW. Histopathological analysis did not reveal changes in tissues. The relative expression reflects overexpression of GPx (p<0.05, fold change: 14.35) and over expression of SOD (p≤0.05, fold change: 0.18) in H. contortus L3 exposed to 97.44 mg/mL of EtOAc-F compared with negative control. The GC-MS analysis revealed the presence of 4-hydroxybenzaldehyde (1), leucoanthocyanidin derivative (2), coniferyl alcohol (3), ferulic acid methyl ester acetate (4), 2,3,4-trimethoxycinnamic acid (5) and epiyangambin (6) as major compounds. According to these results, the EtOAc-F from G. ulmifolia leaves exhibit anthelmintic effect and increased the stress biomarkers on H. contortus.

Unveiling the Role of Oxidative Stress in Cochlear Hair Cell Death: Prospective Phytochemical Therapeutics against Sensorineural Hearing Loss

Hearing loss represents a multifaceted and pervasive challenge that deeply impacts various aspects of an individual's life, spanning psychological, emotional, social, and economic realms. Understanding the molecular underpinnings that orchestrate hearing loss remains paramount in the quest for effective therapeutic strategies. This review aims to expound upon the physiological, biochemical, and molecular aspects of hearing loss, with a specific focus on its correlation with diabetes. Within this context, phytochemicals have surfaced as prospective contenders in the pursuit of potential adjuvant therapies. These compounds exhibit noteworthy antioxidant and anti-inflammatory properties, which hold the potential to counteract the detrimental effects induced by oxidative stress and inflammation-prominent contributors to hearing impairment. Furthermore, this review offers an up-to-date exploration of the diverse molecular pathways modulated by these compounds. However, the dynamic landscape of their efficacy warrants recognition as an ongoing investigative topic, inherently contingent upon specific experimental models. Ultimately, to ascertain the genuine potential of phytochemicals as agents in hearing loss treatment, a comprehensive grasp of the molecular mechanisms at play, coupled with rigorous clinical investigations, stands as an imperative quest.

Abnormal auditory brainstem responses in an animal model of autism spectrum disorder

Auditory dysfunction is a common feature of autism spectrum disorder (ASD) and ranges from deafness to hypersensitivity. The auditory brainstem response (ABR) permits study of the amplitude and latency of synchronized electrical activity along the ascending auditory pathway in response to clicks and pure tone stimuli. Indeed, numerous studies have shown that subjects with ASD have ABR abnormalities. In utero exposure to the antiepileptic drug valproic acid (VPA) is associated with human cases of ASD and is used as an animal model of ASD. Previous studies have shown that VPA-exposed animals have significantly fewer neurons in the auditory brainstem and thalamus, reduced ascending projections to the auditory midbrain and thalamus and increased neuronal activation in response to pure tone stimuli. Accordingly, we hypothesized that VPA-exposed animals would have abnormal ABRs throughout their lifespans. We approached this hypothesis in two cohorts. First, we examined ABRs from both ears on postnatal day 22 (P22). Then, we examined monaural ABRs in animals at P28, 60, 120, 180, 240, 300 and 360. Our results suggest that at P22, VPA-exposed animals have elevated thresholds and increased peak latencies. However, by P60 these differences largely normalize with differences appearing only near hearing threshold. Additionally, our analysis revealed that maturation of ABR waves occurred at different trajectories in control and VPA-exposed animals. These results, together with our previous work, suggest that VPA exposure not only impacts total neuron number and connectivity, but also auditory evoked responses. Finally, our longitudinal analysis suggests that delayed maturation of auditory brainstem circuits may impact ABRs throughout the lifespan of the animal.

Ginkgo biloba Administered Singly and Combined With Antioxidants in Tinnitus Patients

BACKGROUND AND OBJECTIVES

Tinnitus, or ear ringing, involves impulsive and spontaneous activity in the auditory neurons. Its prevalence is high in the elderly, but 10%-15% of adults suffer from tinnitus, affecting their quality of life. Therefore, this study aimed to evaluate the efficacy of Ginkgo biloba administered singly and in combination with antioxidants in tinnitus patients. Subjects and.

METHODS

Patients were randomly allocated to Placebo (T0, n=22), Treatment 1 (T1, n=24), and Treatment 2 (T2, n=23) groups. The patients were educated on the study's methodology and were instructed to visit at 0, 4, 8, 12, and 14 weeks. The placebo group received starch capsule supplements. Conversely, the treatment groups received Ginkgo biloba (60 mg twice a day) singly and in combination with antioxidants. We enrolled 69 patients aged 40-70 years (41 men, 28 women). The Tinnitus Handicap Index (THI), Visual Analogue Score (VAS), and Short Form 36 (SF-36) Health Scores were determined pre- and post-treatment at each visit.

RESULTS

Supplementation of Ginkgo biloba, along with antioxidants, provided marked improvement (p<0.05) in post-treatment THI and VAS scores in the T2 group compared to those in the T1 and T0 groups. The greatest (p<0.05) percent difference was observed in the pre- and post-treatment THI (-36%) and VAS scores (-22.6%) of T2 patients. Likewise, the SF-36 scores improved significantly (p<0.05) in the T2 group in varied parameters.

CONCLUSIONS

Ginkgo biloba, along with antioxidants, can be a promising therapy for tinnitus patients, providing marked improvement in THI, VAS, and SF-36 scores.

Cardiovascular Activity of Ginkgo biloba-An Insight from Healthy Subjects

Ginkgo biloba is the oldest living tree species in the world. Despite less than encouraging clinical results, extracts from its leaves are among the most used herbal preparations in the prevention and treatment of cardiovascular diseases. Most data on the efficacy of Ginkgo biloba on cardiovascular disease is from clinical studies, with few results from healthy subjects. This paper aims to provide a comprehensive review of the mechanisms underlying the known beneficial cardiovascular activities of Ginkgo biloba. It displays myocardial suppressant and vasorelaxant activities ex vivo, potentiating endothelial-dependent and -independent pathways. It improves perfusion in different vascular beds, namely ocular, cochlear, cutaneous, cerebral, and coronary. Although scarce, evidence suggests that Ginkgo biloba displays a heterogeneous effect on tissue perfusion which is dependent on the individual elimination pathways. It displays an acceptable safety profile, with most reported adverse reactions constituting rare occurrences. Collectively, Ginkgo biloba positively impacts cardiovascular physiology, improving hemodynamics and organ perfusion. In the future, better controlled clinical studies should be performed in order to identify the target populations who may benefit the most from pharmacotherapeutic interventions involving Ginkgo biloba.

Ginkgo biloba for tinnitus

BACKGROUND

Tinnitus is a symptom defined as the perception of sound in the absence of an external source. In England alone there are an estimated ¾ million general practice consultations every year where the primary complaint is tinnitus, equating to a major burden on healthcare services. Clinical management strategies include education and advice, relaxation therapy, tinnitus retraining therapy (TRT), cognitive behavioural therapy (CBT), sound enrichment using ear-level sound generators or hearing aids, and drug therapies to manage co-morbid symptoms such as insomnia, anxiety or depression.  OBJECTIVES: To assess the effects of Ginkgo biloba for tinnitus in adults and children.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; CENTRAL (2022, Issue 6); Ovid MEDLINE; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 7 June 2022.

SELECTION CRITERIA

Randomised controlled trials (RCTs) recruiting adults and children with acute or chronic subjective tinnitus. We included studies where the intervention involved Ginkgo biloba and this was compared to placebo, no intervention, or education and information. Concurrent use of other medication or other treatment was acceptable if used equally in each group. Where an additional intervention was used equally in both groups, we analysed this as a separate comparison. The review included all courses of Ginkgo biloba, regardless of dose regimens or formulations, and for any duration of treatment.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were tinnitus symptom severity measured as a global score on a multi-item tinnitus questionnaire and serious adverse effects (bleeding, seizures). Our secondary outcomes were tinnitus loudness (change in subjective perception), tinnitus intrusiveness, generalised depression, generalised anxiety, health-related quality of life and other adverse effects (gastrointestinal upset, headache, allergic reaction). We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

This review included 12 studies (with a total of  1915 participants). Eleven studies compared the effects of Ginkgo biloba with placebo and one study compared the effects of Ginkgo biloba with hearing aids to hearing aids alone. All included studies were parallel-group RCTs. In general, risk of bias was high or unclear due to selection bias and poor reporting of allocation concealment and blinding of participants, personnel and outcome assessments. Due to heterogeneity in the outcomes measured and measurement methods used, only limited data pooling was possible.  Ginkgo biloba versus placebo When we pooled data from two studies for the primary outcome tinnitus symptom severity, we found that Ginkgo biloba may have little to no effect (Tinnitus Handicap Inventory scores) at three to six months compared to placebo, but the evidence is very uncertain (mean difference (MD) -1.35 (scale 0 to 100), 95% confidence interval (CI) -8.26 to 5.55; 2 studies; 85 participants) (very low-certainty). Ginkgo biloba may result in little to no difference in the risk of bleeding or seizures, with no serious adverse effects reported in either group (4 studies; 1154 participants; low-certainty). For the secondary outcomes, one study found that there may be little to no difference between the effects of Ginkgo biloba and placebo on tinnitus loudness measured with audiometric loudness matching at 12 weeks, but the evidence is very uncertain (MD -4.00 (scale -10 to 140 dB), 95% CI -13.33 to 5.33; 1 study; 73 participants) (very low-certainty). One study found that there may be little to no difference between the effects of Ginkgo biloba and placebo on health-related quality of life measured with the Glasgow Health Status Inventory at three months (MD -0.58 (scale 0 to 100), 95% CI -4.67 to 3.51; 1 study; 60 participants) (low-certainty). Ginkgo biloba may not increase the frequency of other adverse effects (gastrointestinal upset, headache, allergic reaction) at three months compared to placebo (risk ratio 0.91, 95% CI 0.52 to 1.60; 4 studies; 1175 participants) (low-certainty). None of the studies reported the other secondary outcomes of tinnitus intrusiveness or changes in depressive symptoms or depression, anxiety symptoms or generalised anxiety. Gingko biloba with concurrent intervention versus concurrent intervention only One study compared Ginkgo biloba with hearing aids to hearing aids only. It assessed the mean difference in the change in Tinnitus Handicap Inventory scores and tinnitus loudness using a 10-point visual analogue scale (VAS) at three months. The study did not report adverse effects, tinnitus intrusiveness, changes in depressive symptoms or depression, anxiety symptoms or generalised anxiety, or health-related quality of life. This was a single, very small study (22 participants) and for all outcomes the certainty of the evidence was very low. We were unable to draw meaningful conclusions from the numerical results.

AUTHORS' CONCLUSIONS

There is uncertainty about the benefits and harms of Ginkgo biloba for the treatment of tinnitus when compared to placebo. We were unable to draw meaningful conclusions regarding the benefits and harms of Ginkgo biloba when used with concurrent intervention (hearing aids). The certainty of the evidence for the reported outcomes, assessed using GRADE, ranged from low to very low. Future research into the effectiveness of Ginkgo biloba in patients with tinnitus should use rigorous methodology. Randomisation and blinding should be of the highest quality, given the subjective nature of tinnitus and the strong likelihood of a placebo response. The CONSORT statement should be used in the design and reporting of future studies. We also recommend the use of validated, patient-centred outcome measures for research in the field of tinnitus.

Preventive Effects of Ginkgo-Extract EGb 761® on Noise Trauma-Induced Cochlear Synaptopathy

Noise trauma-induced loss of ribbon synapses at the inner hair cells (IHC) of the cochlea may lead to hearing loss (HL), resulting in tinnitus. We are convinced that a successful and sustainable therapy of tinnitus has to treat both symptom and cause. One of these causes may be the mentioned loss of ribbon synapses at the IHC of the cochlea. In this study, we investigated the possible preventive and curative effects of the Ginkgo biloba extract EGb 761® on noise-induced synaptopathy, HL, and tinnitus development in Mongolian gerbils (Meriones unguiculatus). To this end, 37 male animals received EGb 761® or placebo orally 3 weeks before (16 animals) or after (21 animals) a monaural acoustic noise trauma (2 kHz, 115 dB SPL, 75 min). Animals' hearing thresholds were determined by auditory brainstem response (ABR) audiometry. A possible tinnitus percept was assessed by the gap prepulse inhibition acoustic startle reflex (GPIAS) response paradigm. Synaptopathy was quantified by cochlear immunofluorescence histology, counting the ribbon synapses of 15 IHCs at 11 different cochlear frequency locations per ear. We found a clear preventive effect of EGb 761® on ribbon synapse numbers with the surprising result of a significant increase in synaptic innervation on the trauma side relative to placebo-treated animals. Consequently, animals treated with EGb 761® before noise trauma did not develop a significant HL and were also less affected by tinnitus compared to placebo-treated animals. On the other hand, we did not see a curative effect (EGb 761® treatment after noise trauma) of the extract on ribbon synapse numbers and, consequently, a significant HL and no difference in tinnitus development compared to the placebo-treated animals. Taken together, EGb 761® prevented noise-induced HL and tinnitus by protecting from noise trauma-induced cochlear ribbon synapse loss; however, in our model, it did not restore lost ribbon synapses.

Circadian Sensitivity of Noise Trauma-Induced Hearing Loss and Tinnitus in Mongolian Gerbils

Noise-induced hearing loss (HL) has a circadian component: In nocturnal mice, hearing thresholds (HT) have a significantly stronger effect to acoustic trauma when induced during the night compared to rather mild effects on hearing when induced during daytime. Here, we investigate whether such effects are also present in diurnal Mongolian gerbils and determined whether trauma-induced HL correlated with the development of a tinnitus percept in these animals. In particular, we investigated the effects of acoustic trauma (2 kHz, 115 dB SPL, 75 min) on HT and tinnitus development in 34 male gerbils exposed either at 9 AM, 1 PM, 5 PM, or 12 PM. HT was measured by acoustic brainstem response audiometry at defined times 1 day before and 1 week after the trauma. Possible tinnitus percepts were assessed behaviorally by the gap prepulse inhibition of the acoustic startle response at defined times 1 day before and 1 week after the trauma. We found daytime-dependent changes due to trauma in mean HT in a frequency-dependent manner comparable to the results in mice, but the results temporally shifted according to respective activity profiles. Additionally, we found linear correlations of these threshold changes with the strength of the tinnitus percept, with the most prominent correlations in the 5 PM trauma group. Taken together, circadian sensitivity of the HT to noise trauma can also be found in gerbils, and tinnitus strength correlates most strongly with HL only when the trauma is applied at the most sensitive times, which seem to be the evening.

Overview on immobilization of enzymes on synthetic polymeric nanofibers fabricated by electrospinning

The arrangement and type of support has a significant impact on the efficiency of immobilized enzymes. 1-dimensional fibrous materials can be one of the most desirable supports for enzyme immobilization. This is due to their high surface area to volume ratio, internal porosity, ease of handling, and high mechanical stability, all of which allow a higher enzyme loading, release and finally lead to better catalytic efficiency. Fortunately, the enzymes can reside inside individual nanofibers to remain encapsulated and retain their three-dimensional structure. These properties can protect the enzyme's tolerance against harsh conditions such as pH variations and high temperature, and this can probably enhance the enzyme's stability. This review article will discuss the immobilization of enzymes on synthetic polymers, which are fabricated into nanofibers by electrospinning. This technique is rapidly gaining popularity as one of the most practical ways to fibricate polymer, metal oxide, and composite micro or nanofibers. As a result, there is interest in using nanofibers to immobilize enzymes. Furthermore, present research on electrospun nanofibers for enzyme immobilization is primarily limited to the lab scale and industrial scale is still challanging. The primary future research objectives of this paper is to investigate the use of electrospun nanofibers for enzyme immobilization, which includes increasing yield to transfer biological products into commercial applications.

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.

Tinnitus development is associated with synaptopathy of inner hair cells in Mongolian gerbils

Human hearing loss (HL) is often accompanied by comorbidities like tinnitus, which is affecting up to 15% of the adult population. Rodent animal studies could show that tinnitus may not only be a result of apparent HL due to cochlear hair cell damage but can also be a consequence of synaptopathy at the inner hair cells (IHCs) already induced by moderate sound traumata. Here, we investigate synaptopathy previously shown in mice in our animal model, the Mongolian gerbil, and relate it to behavioral signs of tinnitus. Tinnitus was induced by a mild monaural acoustic trauma leading to monaural noise induced HL in the animals, quantified by auditory brainstem response (ABR) audiometry. Behavioral signs of tinnitus percepts were detected by measurement of prepulse inhibition of the acoustic startle response in a gap-noise paradigm. Fourteen days after trauma, the cochleae of both ears were isolated, and IHC synapses were counted within several spectral regions of the cochlea. Behavioral signs of tinnitus were only found in animals with IHC synaptopathy, independent of type of HL. On the other hand, animals with apparent HL but without behavioral signs of tinnitus showed a reduction in amplitudes of ABR waves I&II but no significant changes in the number of synapses at the IHC. We conclude-in line with the literature-that HL is caused by damage to the IHC or by other reasons but that the development of tinnitus, at least in our animal model, is closely linked to synaptopathy at the IHC.

Clinical randomized trial study of hearing aids effectiveness in association with Ginkgo biloba extract (EGb 761) on tinnitus improvement

Introduction

Tinnitus is defined as the perception of sound without its actual presence in the environment. It has been the subject of a great number of studies, especially considering its consequences on patient's quality of life.

Objective

This study aimed to investigate the effect of hearing aids and/or Ginkgo biloba extract EGb 761 on tinnitus in patients with hearing loss.

Methods

This is a trial randomized-controlled treatment, parallel, double-blind, with three-arm. Thirty-three adults subjects were divided into three groups: group 1 — subjects undergoing drug therapy with Ginkgo biloba extract EGb 761; group 2 — individuals fitted with digital hearing aids; group 3 — individuals submitted to drug therapy with Ginkgo biloba extract EGb 761 and using hearing aids. The tinnitus handicap inventory and visual analogue scale were used to evaluate self-perception of tinnitus loudness and severity before treatment and 90 days after treatment.

Results

This study demonstrated a significant correlation between tinnitus handicap inventory and visual analogue scale, before and after treatment. We observed a significant improvement in self-perception of tinnitus loudness and severity after 90 days of treatment with Ginkgo biloba extract EGb 761 and/or hearing aids. No correlation was found between tinnitus onset time and self-perception of tinnitus loudness and severity. Hearing aids were more effective in patients with a shorter tinnitus onset time and Ginkgo biloba extract was effective regardless of tinnitus duration.

Conclusions

It was possible to prove the effectiveness of the hearing aids and/or Ginkgo biloba extract EGb 761 treatment, which shows success in the control of tinnitus contributing to the improvement of this symptom.

Drug development for noise-induced hearing loss

INTRODUCTION

Excessive exposure to noise is a common occurrence that contributes to approximately 50% of the non-genetic hearing loss cases. Researchers need to develop standardized preclinical models and identify molecular targets to effectively develop prevention and curative therapies.

AREAS COVERED

In this review, the authors discuss the many facets of human noise-induced pathology, and the primary experimental models for studying the basic mechanisms of noise-induced damage, making connections and inferences among basic science studies, preclinical proofs of concept and clinical trials.

EXPERT OPINION

Whilst experimental research in animal models has helped to unravel the mechanisms of noise-induced hearing loss, there are often methodological variations and conflicting results between animal and human studies which make it difficult to integrate data and translate basic outcomes to clinical practice. Standardization of exposure paradigms and application of -omic technologies will contribute to improving the effectiveness of transferring newly gained knowledge to clinical practice.

Enzymatic degradation of ginkgolic acid by laccase immobilized on novel electrospun nanofiber mat

BACKGROUND

Ginkgo biloba leaf extract contains many active ingredients that are beneficial for health. However, ginkgolic acid, one of the major components found in G. biloba extract, may cause serious allergic and toxic side effects. The purpose of this study is to immobilize the laccase system on the electrospun nylon fiber mat (NFM) to hydrolyze the ginkgolic acid in G. biloba leaf extract efficiently.

RESULTS

Novel electrospinning technology successfully produced high-quality nanoscopic fiber mats made of a mixture of multi-walled carbon nanotube and nylon 6,6. Laccase that was immobilized onto the NFM exhibited much higher efficiency in the catalyzation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) than nylon 6,6 pellets. After being immobilized onto the NFM, the pH and temperature stability of laccase were significantly improved. The NFM-immobilized laccase could maintain more than 50% of its original activity even after 40 days of storage or 10 operational cycles. The kinetic parameters, including rate constant (K), the time (τ50) in which 50% of ginkgolic acid hydrolysis was reached, the time (τcomplete) required to achieve complete ginkgolic acid hydrolysis, Km and Vmax were determined, and were 0.07 ± 0.01 min^-1 , 8.97 ± 0.55 min, 45.45 ± 2.79 min, 0.51 ± 0.09 mM and 0.49 ± 0.03 mM min^-1  mg^-1 , respectively.

CONCLUSION

The result successfully demonstrated the strong potential of using novel electrospun nanofiber mats as enzyme immobilization platforms, which could significantly enhance enzyme activity and stability. © 2020 Society of Chemical Industry.

Morphogenesis and vitality of seedlings of Ginkgo biloba in outdoor conditions

Ginkgo biloba L. is a relic tree that is preserved in natural conditions only in China. In the North-East Ukraine ginkgo is only in the process of introduction, but in certain places ginkgo trees are grown for decorative purposes which show high vitality. Therefore a relevant and promising task is the creation of industrial plantations of ginkgo for collection of its leaves. The objective of the study was morphological peculiarities of ginkgo plants and their vital condition depending on the calendar age of the seedlings at the stage when they were transplanted into the soil. For growing ginkgo, in our studies, a combined two-stage system was approbated, accor­ding to which seedlings were grown in greenhouses during 2–3 years, and then moved into soil outdoors. In our study, as planting material we used seedlings of ginkgo from a plant nursery (greenhouse) of Sumy National Agrarian University planted in 2014 and 2015. Seedlings were planted in the soil in early spring. Seedlings for growth completion were planted in rows with inter-row distance of 0.8 m and distance between the plants measuring 2.5–3.0 m. We studied the condition of the seedlings in two variants: variant 1 – three-year old seedlings obtained in the greenhouse were transplanted in spring 2018; variant 2 – two-year old seedlings obtained in greenhouse were transplanted in spring 2017. Comparative morphometric analysis and evaluation of vitality of these plants was performed in August 2019. Both groups of seedlings were five years old at the time of survey. For evaluation of morphometric structure of the ginkgo seedlings and their vital condition we used randomized selections of specimens in amount of up to 30 from plantations of variants 1 and 2. Analysis of the plants was conducted during the end of the vegetative period of 2019, when active growth of the plants stopped. Four main parameters of the plants were recorded: height, value of annual increment, diameter of the stem near the root neck and the number of leaves. Vital condition of the seedlings was evaluated on the basis of algorithm of vital analysis. Vitality of each seedling was evaluated by the coefficient of Q vitality, value of which was in interval from 0 to 1.0. Depending on the value of Q the seedlings were divided into five classes of vitality: 0–0.2 – cc (specimens of the lowest vitality), 0.2–0.4 – c (low vita­lity), 0.4–0.6 – b (average vitality), 0.6–0.8 – a (high vitality), 0.8–1.0 – aa (specimens with highest vitality). Comparative analysis of morphological peculiarities of the ginkgo seedlings revealed that two-year plants transplanted outdoors from the greenhouse had higher annual increment of the main stem, diameter of stem and number of leaves. Vital condition of such seedlings was the highest and was evaluated using Q index, which ranges between vitality of classes b to aa. This allows recommending a two-stage scheme of growing seedlings of ginkgo in North-East Ukraine. The optimum age for transplanting seedlings from greenhouses to open soil is two years.

Open(G)PIAS: An Open-Source Solution for the Construction of a High-Precision Acoustic Startle Response Setup for Tinnitus Screening and Threshold Estimation in Rodents

The modulation of the acoustic startle reflex (ASR) by a pre-stimulus called pre-pulse inhibition (PPI, for gap of silence pre-stimulus: GPIAS) is a versatile tool to, e.g., estimate hearing thresholds or identify subjective tinnitus percepts in rodents. A proper application of these paradigms depends on a reliable measurement of the ASR amplitudes and an exact stimulus presentation in terms of frequency and intensity. Here, we introduce a novel open-source solution for the construction of a low-cost ASR setup. The complete software for data acquisition and stimulus presentation is written in Python 3.6 and is provided as an Anaconda package. Furthermore, we provide a construction plan for the sensor system based on low-cost hardware components. Exemplary GPIAS data from two animal models (Mus musculus, Meriones unguiculatus) show that the ratio histograms (1-GPIAS) of the gap-pre-stimulus and no pre-stimulus ASR amplitudes can be well described by a log-normal distribution being in good accordance to previous studies with already established setups. Furthermore, it can be shown that the PPI as a function of pre-stimulus intensity (threshold paradigm) can be approximated with a hard-sigmoid function enabling a reproducible sensory threshold estimation. Thus, we show that the open-source solution could help to further establish the ASR method in many laboratories and, thus, facilitate and standardize research in animal models of tinnitus and/or hearing loss.

Traditional oriental medicine for sensorineural hearing loss: Can ethnopharmacology contribute to potential drug discovery?

ETHNOPHARMACOLOGICAL RELEVANCE

In Traditional Oriental Medicine (TOM), the development of hearing pathologies is related to an inadequate nourishment of the ears by the kidney and other organs involved in regulation of bodily fluids and nutrients. Several herbal species have historically been prescribed for promoting the production of bodily fluids or as antiaging agents to treat deficiencies in hearing.

AIM OF REVIEW

The prevalence of hearing loss has been increasing in the last decade and is projected to grow considerably in the coming years. Recently, several herbal-derived products prescribed in TOM have demonstrated a therapeutic potential for acquired sensorineural hearing loss and tinnitus. Therefore, the aims of this review are to provide a comprehensive overview of the current known efficacy of the herbs used in TOM for preventing different forms of acquired sensorineural hearing loss and tinnitus, and associate the traditional principle with the demonstrated pharmacological mechanisms to establish a solid foundation for directing future research.

METHODS

The present review collected the literature related to herbs used in TOM or related compounds on hearing from Chinese, Korean, and Japanese herbal classics; library catalogs; and scientific databases (PubMed, Scopus, Google Scholar; and Science Direct).

RESULTS

This review shows that approximately 25 herbal species and 40 active compounds prescribed in TOM for hearing loss and tinnitus have shown in vitro or in vivo beneficial effects for acquired sensorineural hearing loss produced by noise, aging, ototoxic drugs or diabetes. The inner ear is highly vulnerable to ischemia and oxidative damage, where several TOM agents have revealed a direct effect on the auditory system by normalizing the blood supply to the cochlea and increasing the antioxidant defense in sensory hair cells. These strategies have shown a positive impact on maintaining the inner ear potential, sustaining the production of endolymph, reducing the accumulation of toxic and inflammatory substances, preventing sensory cell death and preserving sensory transmission. There are still several herbal species with demonstrated therapeutic efficacy whose mechanisms have not been deeply studied and others that have been traditionally used in hearing loss but have not been tested experimentally. In clinical studies, Ginkgo biloba, Panax ginseng, and Astragalus propinquus have demonstrated to improve hearing thresholds in patients with sensorineural hearing loss and alleviated the symptoms of tinnitus. However, some of these clinical studies have been limited by small sample sizes, lack of an adequate control group or contradictory results.

CONCLUSIONS

Current therapeutic strategies have proven that the goal of the traditional oriental medicine principle of increasing bodily fluids is a relevant approach for reducing the development of hearing loss by improving microcirculation in the blood-labyrinth barrier and increasing cochlear blood flow. The potential benefits of TOM agents expand to a multi-target approach on different auditory structures of the inner ear related to increased cochlear blood flow, antioxidant, anti-inflammatory, anti-apoptotic and neuroprotective activities. However, more research is required, given the evidence is very limited in terms of the mechanism of action at the preclinical in vivo level and the scarce number of clinical studies published.

[The diagnostics and treatment of tympanophonia]

Tympanophonia can be a consequence of a variety of diseases and pathological conditions diagnostics of which encounters difficulties. The comprehensive clinical examination of the patient is necessary to determine the cause of tympanophonia including elucidation of the following characteristics: initial (acute or gradual) sensation of sound in the ear(s), duration of persisting clinical manifestations, the presence of an acoustic or craniocerebral injury, characteristics of the noise, viz. continuous or intermittent, clicking sounds, paroxysmal or pulsed noise (synchronous with the heart beating), fluctuating, audible to the patient alone or to the surrounding people as well, unilateral and bilateral noises (either symmetric or asymmetric), perception of noise in the head rather than ears., high- and low-pitched noise together with the accompanying neurological symptoms. The analysis of these characteristics makes it possible to differentiate between objective and subjective sensation of noise in the ear(s), determine the amount of additional studies needed for the evaluatio of the conditions of a given patient, identify the possible cause of tympanophonia, establish the nosological diagnosis, and distinguish a group of the patients in need of emergency otological management.

A New Statistical Approach for the Evaluation of Gap-prepulse Inhibition of the Acoustic Startle Reflex (GPIAS) for Tinnitus Assessment

Background: An increasingly used behavioral paradigm for the objective assessment of a possible tinnitus percept in animal models has been proposed by Turner and coworkers in 2006. It is based on gap-prepulse inhibition (PPI) of the acoustic startle reflex (ASR) and usually referred to as GPIAS. As it does not require conditioning it became the method of choice to study neuroplastic phenomena associated with the development of tinnitus. Objective: It is still controversial if GPIAS is really appropriate for tinnitus screening, as the hypothesis that a tinnitus percept impairs the gap detection ability ("filling-in interpretation" is still questioned. Furthermore, a wide range of criteria for positive tinnitus detection in GPIAS have been used across different laboratories and there still is no consensus on a best practice for statistical evaluation of GPIAS results. Current approaches are often based on simple averaging of measured PPI values and comparisons on a population level without the possibility to perform valid statistics on the level of the single animal. Methods: A total number of 32 animals were measured using the standard GPIAS paradigm with varying number of measurement repetitions. Based on this data further statistical considerations were performed. Results: We here present a new statistical approach to overcome the methodological limitations of GPIAS. In a first step we show that ASR amplitudes are not normally distributed. Next we estimate the distribution of the measured PPI values by exploiting the full combinatorial power of all measured ASR amplitudes. We demonstrate that the amplitude ratios (1-PPI) are approximately lognormally distributed, allowing for parametrical testing of the logarithmized values and present a new statistical approach allowing for a valid and reliable statistical assessment of PPI changes in GPIAS. Conclusion: Based on our statistical approach we recommend using a constant criterion, which does not systematically depend on the number of measurement repetitions, in order to divide animals into a tinnitus and a non-tinnitus group. In particular, we recommend using a constant threshold based on the effect size as criterion, as the effect size, in contrast to the p-value, does not systematically depend on the number of measurement repetitions.

Clinical effect of intratympanic dexamethasone injection in acute unilateral tinnitus: A prospective, placebo-controlled, multicenter study

OBJECTIVE

The purpose of this study was to investigate the effectiveness of intratympanic dexamethasone injection (ITDI) in acute tinnitus of presumed cochlear origin.

STUDY DESIGN

A prospective, randomized, placebo-controlled, double-blinded, multicenter study.

METHODS

Between August 2013 and December 2015, 54 patients with unilateral tinnitus were enrolled at four different centers. Patients were assigned either to an ITDI (n = 27) or an intratympanic normal saline injection (ITNI; n = 27) group through block randomization. Intratympanic injections were administered four times over 2 weeks. At 4 weeks after initial injection, we analyzed the improvement rates of tinnitus using the tinnitus handicap Inventory (THI) and visual analogue scale (VAS) for loudness, awareness, and annoyance. We defined improvement as the reduction of more than 7 points or of more than 20% in the final THI score compared to the initial THI score.

RESULTS

The initial mean hearing thresholds and VAS and THI scores of the two groups did not differ significantly. At 4 weeks after initial injection, the mean VAS and THI scores of both groups had significantly reduced. However, the improvement rate did not differ significantly between the groups (ITDI, 51.9%; ITNI, 59.3%).

CONCLUSION

The results indicate that ITDI might not be more effective than ITNI for the treatment of acute unilateral tinnitus. Therefore, ITDI should not be considered as the main treatment for patients presenting with acute tinnitus as the primary symptom.

LEVEL OF EVIDENCE

1b. Laryngoscope, 128:184-188, 2018.