Hearing loss and brain disorders: A review of multiple pathologies.

Several causative factors are associated with hearing loss (HL) and brain disorders. However, there are many unidentified disease modifiers in these conditions. Our study summarised the most common brain disorders associated with HL and highlighted mechanisms of pathologies. We searched the literature for published articles on HL and brain disorders. Alzheimer's disease/dementia, Parkinson's disease, cognitive impairment, autism spectrum disorder, ataxia, epilepsy, stroke, and hypoxic-ischaemic encephalopathy majorly co-interact with HL. The estimated incidence rate was 113 per 10,000 person-years. Genetic, epigenetic, early life/neonatal stress, hypoxia, inflammation, nitric oxide infiltration, endoplasmic reticulum stress, and excess glutamate were the distinguished modifiers identified. Various mechanisms like adhesion molecules, transport proteins, hair cell apoptosis, and neurodegeneration have been implicated in these conditions and are serving as potential targets for therapies. To improve the quality of life of patients, these understandings will improve clinical diagnoses and management of HL and brain disorders.

Methyl jasmonate delays the latency to anoxic convulsions by normalizing the brain levels of oxidative stress biomarkers and serum corticosterone contents in mice with repeated anoxic stress.

OBJECTIVES: Repeated exposure to anoxic stress damages the brain through cortisol-mediated increases in oxidative stress and cellular-antioxidants depletion. Thus, compounds with antioxidant property might confer protection against anoxic stress-induced brain injuries. In this study, we further examined the protective effect of methyl jasmonate (MJ), a potent anti-stress agent against anoxic stress-induced convulsions in mice. METHODS: Thirty-six male Swiss mice randomized into six groups (n=6) were given MJ (25, 50 and 100 mg/kg, i.p.) or vehicle (10 mL/kg, i.p.) 30 min before 15 min daily exposure to anoxic stress for 7 days. The latency(s) to anoxic convulsion was recorded on day 7. The blood glucose and serum corticosterone levels were measured afterwards. The brains were also processed for the determination of malondialdehyde, nitrite, and glutathione levels. RESULTS: Methyl jasmonate (MJ) delayed the latency to anoxic convulsion and reduced the blood glucose and serum corticosterone levels. The increased malondialdehyde and nitrite contents accompanied by decreased glutathione concentrations in mice with anoxic stress were significantly attenuated by MJ. CONCLUSIONS: These findings further showed that MJ possesses anti-stress property via mechanisms relating to the reduction of serum contents of corticosterone and normalization of brain biomarker levels of oxidative stress in mice with anoxic stress.

Hearing Impairment Overview in Africa: the Case of Cameroon.

The incidence of hearing impairment (HI) is higher in low- and middle-income countries when compared to high-income countries. There is therefore a necessity to estimate the burden of this condition in developing world. The aim of our study was to use a systematic approach to provide summarized data on the prevalence, etiologies, clinical patterns and genetics of HI in Cameroon. We searched PubMed, Scopus, African Journals Online, AFROLIB and African Index Medicus to identify relevant studies on HI in Cameroon, published from inception to 31 October, 2019, with no language restrictions. Reference lists of included studies were also scrutinized, and data were summarized narratively. This study is registered with PROSPERO, number CRD42019142788. We screened 333 records, of which 17 studies were finally included in the review. The prevalence of HI in Cameroon ranges from 0.9% to 3.6% in population-based studies and increases with age. Environmental factors contribute to 52.6% to 62.2% of HI cases, with meningitis, impacted wax and age-related disorder being the most common ones. Hereditary HI comprises 0.8% to 14.8% of all cases. In 32.6% to 37% of HI cases, the origin remains unknown. Non-syndromic hearing impairment (NSHI) is the most frequent clinical entity and accounts for 86.1% to 92.5% of cases of HI of genetic origin. Waardenburg and Usher syndromes account for 50% to 57.14% and 8.9% to 42.9% of genetic syndromic cases, respectively. No pathogenic mutation was described in GJB6 gene, and the prevalence of pathogenic mutations in GJB2 gene ranged from 0% to 0.5%. The prevalence of pathogenic mutations in other known NSHI genes was <10% in Cameroonian probands. Environmental factors are the leading etiology of HI in Cameroon, and mutations in most important HI genes are infrequent in Cameroon. Whole genome sequencing therefore appears as the most effective way to identify variants associated with HI in Cameroon and sub-Saharan Africa in general.

The Hearing Impairment Ontology: A Tool for Unifying Hearing Impairment Knowledge to Enhance Collaborative Research.

Hearing impairment (HI) is a common sensory disorder that is defined as the partial or complete inability to detect sound in one or both ears. This diverse pathology is associated with a myriad of phenotypic expressions and can be non-syndromic or syndromic. HI can be caused by various genetic, environmental, and/or unknown factors. Some ontologies capture some HI forms, phenotypes, and syndromes, but there is no comprehensive knowledge portal which includes aspects specific to the HI disease state. This hampers inter-study comparability, integration, and interoperability within and across disciplines. This work describes the HI Ontology (HIO) that was developed based on the Sickle Cell Disease Ontology (SCDO) model. This is a collaboratively developed resource built around the 'Hearing Impairment' concept by a group of experts in different aspects of HI and ontologies. HIO is the first comprehensive, standardized, hierarchical, and logical representation of existing HI knowledge. HIO allows researchers and clinicians alike to readily access standardized HI-related knowledge in a single location and promotes collaborations and HI information sharing, including epidemiological, socio-environmental, biomedical, genetic, and phenotypic information. Furthermore, this ontology illustrates the adaptability of the SCDO framework for use in developing a disease-specific ontology.

Anti-inflammatory and membrane stabilizing properties of methyl jasmonate in rats.

The present investigation was carried out to evaluate anti-inflammatory and membrane stabilizing properties of methyl jasmonate (MJ) in experimental rat models of acute and chronic inflammation. The effects of MJ on acute inflammation were assessed using carrageenan-induced rat's paw edema model. The granuloma air pouch model was employed to evaluate the effects of MJ on chronic inflammation produced by carrageenan in rats. The number of white blood cells (WBC) in pouch exudates was estimated using light microscopy. The levels of biomarkers of oxidative stress, such as malondialdehyde (MDA), glutathione (GSH) and activity of antioxidant enzymes in the exudates, were determined using spectrophotometry. The membrane stabilizing property of MJ was assessed based on inhibition of hemolysis of rat red blood cells (RBC) exposed to hypotonic medium. Our results indicated that MJ (25-100 mg·kg-1, i.p.) produced significant anti-inflammatory activity in carrageenan-induced paw edema in rats (P < 0.05). MJ reduced the volume of pouch exudates and the number of WBC in carrageenan-induced granulomatous inflammation. It also exhibited potent antioxidant and membrane stabilizing activities. In conclusion, these findings suggest the therapeutic potentials of methyl jasmonate in disease conditions associated with inflammation and its anti-inflammatory activity may be related to its antioxidant and membrane stabilizing activities.

Anti-inflammatory effects and anti-oxidant capacity of Myrathius arboreus (Cecropiaceae) in experimental models.

BACKGROUND: Inflammation is involved in various diseases; search for safe treatments is warranted. Anti-inflammatory effects of ethanol extract of Myrathius arboreus (EEMa) were studied in carrageenan-induced model, formaldehyde sub-acute-induced model, and in 48 h lipopolysaccharide-induced air pouch model of inflammation. EEMa membrane-stabilizing activities and anti-oxidant capacity were determined in vitro. METHODS: In the carrageenan model EEMa (125, 250, or 500 mg/kg), indomethacin (5 mg/kg), or vehicle 3 mL/kg was administered orally in rats (n=5). After 1 h, 0.1 mL of 1% carrageenan was injected into the right hind paw of rats. Change in edema sizes was measured for 3 h with plethysmometer. One-tenth milliliter (0.1 mL) of 2.5% formaldehyde was injected into the rat paw on the first day and the third day to induce sub-acute inflammation; changes in the edema sizes were determined, and percentages of inhibitions were calculated. Anti-inflammatory effects of EEMa were further examined in lipopolysaccharide (LPS)-induced air-pouch based on leukocytes count, volume of exudates, levels of malondialdehyde, glutathione, superoxide dismutase, nitric oxides, and tumor necrosis factor released into the inflammatory fluids. EEMa-free radicals scavenging activities were studied in DPPH and reducing power tests. Membrane-stabilizing activities of EEMa were evaluated in the red blood cell lysis induced by thermal and hypotonic solution. RESULTS: EEMa (250, 500 mg/kg) produced significant (p<0.001; p<0.05) inhibition of inflammation when compared with vehicle. Also, EEMa (250, 500, or 1000 µg/mL) significantly stabilized membrane and produced free radical scavenging activities. CONCLUSIONS: M. arboreus possesses anti-inflammatory and the anti-oxidant properties that might benefit translational medicine.

Jobelyn® exhibited anti-inflammatory, antioxidant, and membrane-stabilizing activities in experimental models.

BACKGROUND: Jobelyn® (JB) is an African sorghum-based food supplement claimed to be efficacious for the treatment of rheumatoid arthritis (RA). Although in vitro studies confirmed its anti-inflammatory property, no study had shown the effect of JB using in vivo animal models of inflammation. Thus, its effects on acute and chronic inflammation in rats were evaluated in this study. Its effect on rat red blood cell (RBC) lysis was also assessed. METHODS: Acute inflammation was induced with intraplanter injection of carrageenan and increase in rat paw volume was measured using plethysmometer. The volume of fluid exudates, number of leukocytes, concentrations of malondialdehyde (MDA), and glutathione (GSH) in the fluid were measured on day 5 after induction of chronic inflammation with carrageenan in the granuloma air pouch model. RBC lysis induced by hypotonic medium as determined by release of hemoglobin was measured spectrophotometerically. RESULTS: JB (50-200 mg/kg) given orally produced a significant inhibition of acute inflammation induced by carrageenan in rats. It reduced the volume and number of leukocytes in inflammatory fluid in the granuloma air pouch model of chronic inflammation. It further decreased the levels of MDA in the fluid suggesting antioxidant property. JB elevated the concentrations of GSH in inflammatory exudates indicating free radical scavenging activity. It also significantly inhibited RBC lysis caused by hypotonic medium, suggesting membrane-stabilizing property. CONCLUSIONS: JB has in vivo anti-inflammatory activity, which may be related to its antioxidant and membrane-stabilizing properties, supporting its use for the treatment of arthritic disorder.

Anti-inflammatory effects of aqueous extract of Mangifera indica in Wistar rats.

BACKGROUND: Recent studies in standard laboratories have indicated that a typical mango stem bark aqueous extract (Magnifera indica Linn) possess anti-malaria and anti-fever properties. Recent information also exists in the literature, suggesting its potency as a very effective anti-inflammatory plant extract. This study will therefore contribute immensely to the systemic search for a useful, less toxic and natural bioactive medicinal compound. OBJECTIVES: This study investigated the anti-inflammatory effects of the aqueous extract of Mangifera indica (MI) in a carrageenin-induced rat paw oedema model of acute inflammation. METHODS: Rats (n=5) were treated orally with MI (50, 100 and 200 mg/kg), acetylsalicylic acid (100 mg/kg) or distilled water (3 mL). Thirty minutes later, acute inflammation was induced with a sub-plantar injection of 0.1 mL of 1% carrageenin solution into the right hind paw of the rats. The paw oedema sizes were measured with the aid of a Vernier calliper over a period of 3 hours. RESULTS: The aqueous extract of MI (50-200 mg/kg, p.o.) produced a dose-dependent and significant inhibition of the acute inflammation induced by the carrageenin in rats when compared with controls. The percentage inhibition of oedema formation produced by MI (200 mg/kg, p.o.) was similar to that elicited by acetylsalicylic acid (100 mg/kg, p.o.). CONCLUSIONS: The results of this preliminary investigation suggest that MI contains active compounds with an anti-inflammatory activity. However, more detailed studies using additional models are necessary to further characterise the effects of MI in inflammatory disorders.