Prevalence and risk factors associated with multidrug-resistant bacteria in COVID-19 patients.

Bacterial coinfection among patients with confirmed coronavirus disease 2019 (COVID-19) is a critical medical concern that increases the disease severity and mortality rate. The current study is aimed at evaluating the effects of bacterial coinfections among COVID-19 patients, especially in relation to degree of severity and mortality. A retrospective study was conducted for patients with positive COVID-19 test, admitted to a regional COVID-19 hospital in Jeddah, Saudi Arabia, between May and August 2020. A specimen (e.g., blood, urine, or sputum) was collected from patients with confirmed COVID-19, and was cultured to determine bacterial coinfection caused by multidrug resistant (MDR) bacteria. COVID-19 patients were categorized into 2 groups based on the result of bacterial coinfection culture, as COVID-19 patients with coinfection and COVID-19 patients without coinfection. Independent sample t test or Mann-Whitney U test was used to compare age and hospitalization period between these groups. In addition, binominal logistic regression was applied to identify risk factors associated with mortality and bacterial coinfection. The study included 342 patients with laboratory confirmed COVID-19. Eighty (23.3%) patients were diagnosed with bacterial coinfection, while the remaining 262 (76.6%) patients did not test positive for bacterial coinfection. Length of hospital stay was prolonged among COVID-19 patients diagnosed with bacterial coinfection (16.01 ±â€…11.36 days) when compared with patients without bacterial coinfection (6.5 ±â€…6.12 days). Likewise, the mortality rate was significantly higher among COVID-19 patients with bacterial coinfection (90%) compared to those without bacterial coinfection (49.2%). Gram-negative bacteria were predominant compared to gram-positive, as Klebsiella pneumoniae (35 [43.8%]) and Acinetobacter baumanni (32 [40%]). On the other hand, Staphylococcus aureus (4 [5%]), Enterococcus faecalis (1 [1.3%]), and Enterococcus faecium (1 [1.3%]) were identified as gram-positive bacterial species from recruited patients. The findings of the current study showed that prolong hospitalization is the main risk factor associated with bacterial coinfection and death. Thus, health care providers should minimize hospitalization as well as following a continuous monitoring for bacterial coinfection among COVID-19 patients, to control the spread of infection and reducing the severity and mortality rate among COVID-19 patients.

Cognitive Flexibility's Role in Reducing Academic Stress During the COVID-19 Pandemic.

Background: Cognitive flexibility (CF) in the psychological literature has been described as an individual's ability to produce several solutions and retain control in novel situations. Recently, the COVID-19 pandemic appeared to be an ideal scenario that demanded the application of adaptive thinking by students to deal with several challenges of the pandemic. Aim: This study aimed to assess the role of CF in reducing academic stress among university students due to the sudden and strict implementation of online education during the COVID-19 pandemic. Methods: This study employed a cross-sectional survey design and data collection was completed during the 2020-2021 academic year. The study sample comprised 328 university students from Saudi Arabia. The online survey method was used, and study tools comprises of reliable and valid psychological measures to assess CF, academic stress, the negative impact of the COVID-19 pandemic, and emotional symptoms. IBMSPSS25 was used for statistical analysis of data. Multiple regression analysis was applied to determine the role of CF in reducing academic stress after controlling for other factors such as gender, age, academic year, negative impact of COVID-19 on daily life, and unpleasant emotional experiences. Results: CF was significantly decreased the risk of experiencing academic stress (b = ‒0.196, t = ‒3.54; p < 0.001; 95% CI = ‒3.53 to ‒0.11) after controlling for the negative impact of the COVID-19 pandemic on daily life (b = 0.119, t = 2.09; p < 0.05; 95% CI = 0.02-0.63) and emotional repercussions (b = 0.109, t = 1.91; p < 0.05; 95% CI = ‒0.01-0.15). Conclusion: The current findings suggest that CF could be fostered among university students as a useful mental tool to cope with academic stress during less-structured educational and social circumstances that may impact their daily lives and emotional wellness.

Comparison of Hematological Parameters Between Survivors and Non-Survivors COVID-19 Patients in Saudi Arabia.

Objective: Coronavirus disease 2019, caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is a communicable disease transmitted through the respiratory route and bodily contact. The severity of infection and mortality rate of COVID-19 cases was significantly high in the initial stages of the pandemic. This study aims to investigate the hematological profile of COVID-19 survivors and non-survivors. Methods: This is a single-center retrospective study. A total of 108 hospitalized patients with laboratory-confirmed COVID-19 at East Jeddah Hospital between April and August 2020 were categorized into two groups based on outcome as survivors (n = 54) and non-survivors (n = 54). Hematological parameters and clinical profiles were analyzed and compared between the two groups. Results: The mean age and standard deviation of the survived (30-71 years) and non-survived (33-83) groups was 53 ± 10.8 and 57.9 ± 12.2 years, respectively, with no statistically significant difference in age between groups (p = 0.0513). Non-survivors had a significantly longer median length of stay in the intensive care unit (ICU) (7 days, IQR: 4.24 to 12) compared to survivors COVID-19 patients (5 days, IQR: 0 to 11.75) (p = 0.0151). For the survivors group, the participant's age positively correlated with the length of hospital stay (r(52) = 0.21, p = 0.0005) and ICU length of stay r(52) = 0.18, p = 0.001). The median red blood cells (RBC) counts were significantly higher in the survived group (4.56x109/L, IQR: 4.02 to 5.11) in comparison with the non-survived (4.23x109/L, IQR: 3.75 to 4.23) group (p = 0.0011). All COVID-19 patients exhibited lymphocytopenia and a significant negative correlation was observed between the lymphocyte values and length of hospital stay among the survived group (p < 0.001) as well as length of ICU stay among the survived group (p < 0.0480). Disease-related mortality was significantly associated with reduced white blood cells (WBCs) (8.5×109/L, IQR: 6.1 to 11.7) and reduced basophils (0.09%, IQR: 0.02 to 0.19). Additionally, statistically significant differences were found between the survived and non-survived groups with respect to prothrombin time (PT) (12.5 sec. vs 14 sec., p < 0.0001) and partial thromboplastin time (PTT) (31.8 sec. vs 40 sec., p = 0.0008). Conclusion: Hematological parameters can serve as valuable indicators to identify patients with severe COVID-19 and expected poor-prognosis/outcomes upon hospital admission. Cell counts of lymphocytes, WBCs, basophils and parameters such as PT and PTT can serve as clinical indicators to assess disease severity and predict progression to critical illness.

Adenylyl cyclase 6 plays a minor role in the mouse inner ear and retina.

Adenylyl cyclase 6 (AC6) synthesizes second messenger cAMP in G protein-coupled receptor (GPCR) signaling. In cochlear hair cells, AC6 distribution relies on an adhesion GPCR, ADGRV1, which is associated with Usher syndrome (USH), a condition of combined hearing and vision loss. ADGRV1 is a component of the USH type 2 (USH2) protein complex in hair cells and photoreceptors. However, the role of AC6 in the inner ear and retina has not been explored. Here, we found that AC6 distribution in hair cells depends on the USH2 protein complex integrity. Several known AC6 regulators and effectors, which were previously reported to participate in ADGRV1 signaling in vitro, are localized to the stereociliary compartments that overlap with AC6 distribution in hair cells. In young AC6 knockout (Adcy6-/-) mice, the activity of cAMP-dependent protein kinase, but not Akt kinase, is altered in cochleas, while both kinases are normal in vestibular organs. Adult Adcy6-/- mice however exhibit normal hearing function. AC6 is expressed in mouse retinas but rarely in photoreceptors. Adcy6-/- mice have slightly enhanced photopic but normal scotopic vision. Therefore, AC6 may participate in the ADGRV1 signaling in hair cells but AC6 is not essential for cochlear and retinal development and maintenance.

Types and Sources of Social Support Accessible to University Students with Disabilities in Saudi Arabia during the COVID-19 Pandemic.

University students with disabilities face an increased risk of experiencing negative implications in educational, psychological, and social spheres during the COVID-19 pandemic. This study aimed at assessing various dimensions of social support and its sources during the COVID-19 pandemic that availed university students with disabilities. This cross-sectional descriptive study collected data from 53 university students with disabilities. We administered the Social Support Scale (SSC) to assess five dimensions: informational, emotional, esteem, social integration and tangible support, and access to social support from four sources: family, friends, teachers, and colleagues. Multiple regression analysis showed that university students with disabilities mainly relied upon their friends for informational support (ß = 0.64; p < 0.001), emotional support (ß = 0.52; p < 0.001), and social integration support (ß = 0.57; p < 0.001). Family members (ß = 0.406; p < 0.01) and colleagues (ß = 0.36; p < 0.01) provided esteem support to students with disabilities. Support from teachers demonstrated an association with informational support (ß = 0.24; p < 0.05). The findings from the current study suggest that students with disabilities primarily sought informational, emotional, and social integration support from their peers. Although teachers were the primary source of informational support, emotional and esteem support were not found to be significantly associated with them. These findings necessitate exploring the underlying factors and how to enhance them during unusual circumstances such as online distance education and social distancing.

Comparative Study of Audiovestibular Symptoms between Early and Late Variants of COVID-19.

Audiovestibular symptoms during the acute phase of the corona virus disease 2019 (COVID-19), have been reported for earlier waves of the pandemic, while no studies investigated nor compared audiovestibular manifestations during subsequent waves of COVID-19. In the current study, we aimed to compare the occurrence of audiovestibular symptoms associated with COVID-19 between the alpha/beta, delta, and omicron variants. An online questionnaire was distributed to individuals with confirmed test results for COVID-19. We asked participants to report whether they experienced audiovestibular symptoms during the acute phase of the disease. The study included 939 participants; 120 un-infected controls and infected participants during alpha/beta (n = 301), delta (n = 102), and omicron (n = 416) predominance periods. Self-reported audiovestibular symptoms were found to be statistically significantly different between un-infected controls and COVID-19 infected individuals in all analyzed variants. Furthermore, our results showed no significant differences in audiovestibular symptoms among individuals infected during alpha/beta, delta, and omicron waves. Although individuals infected during the delta variant predominance period reported higher percentages of audiovestibular symptoms (ranging from 11.8% to 26.5% for auditory symptoms and from 12.7% to 34.3% for vestibular symptoms) than for the alpha/beta (ranging from 6.3% to 18.9% for auditory symptoms and 8.3% to 29.9% for vestibular symptoms) and omicron (ranging from 9.6% to 21.2% for auditory and 12.5 to 29.1% for vestibular symptoms) variants, this did not achieve statistical significance. With regards to auditory symptoms, the most commonly reported symptoms were aural fullness followed by hearing loss and tinnitus. With regards to vestibular symptoms, dizziness was the most commonly reported symptom followed by vertigo and unsteadiness. Logistic regression revealed that experiencing auditory symptoms were associated with other neurological symptoms, back and joint pain, and chest pain as COVID-19 symptoms. Vestibular symptoms were associated with anemia, gender, fatigue, headache, and breathing difficulties. In conclusion, our study shows that audiovestibular symptoms are common during the acute phase of early and late COVID-19 variants with no significant differences between them.

Knowledge of cytomegalovirus infection among women in Saudi Arabia: A cross-sectional study.

BACKGROUND: Cytomegalovirus (CMV) is the most common intrauterine congenital infection in humans. Worldwide seropositive rates of CMV are considerably high among women of childbearing age. There is currently no optimal drug treatment nor a vaccine for congenital CMV infection and therefore the best available program to date of prevention is practicing standard hygienic measures. The success of this program relies on women's knowledge of CMV modes of transmissions, and risk and preventative behaviors. OBJECTIVE: The current study aims to assess the awareness and knowledge of CMV infection among women in Saudi Arabia. METHOD: In this cross-sectional study, an online self-administered questionnaire was distributed to women 18 years of age or older residing in all regions of Saudi Arabia. The questionnaire included questions to assess awareness of CMV, knowledge of symptoms, transmission, and preventative measures of CMV infection. RESULTS: Out of the 1004 women who completed the questionnaire, self-reported knowledge of CMV was considerably low with only 82 women (8.17%) having heard of CMV infection. Most women reported learning about CMV from the internet and university. In binary logistic analyses, women pursuing studies in healthcare and those working in health professions, as well as those with undergraduate and graduate college degrees were significantly associated with higher knowledge of CMV. Urban area of residence was significantly associated with lower levels of knowledge of CMV. Among women who reported they had heard of CMV, their knowledge of CMV modes of transmission, symptoms, and preventative measures was considerably low. Regarding the transmission route, 23% reported no knowledge of modes of transmission, 59.75% reported mother-to-child transmission, 48.78% reported sexual intercourse, and 45% reported contact with body fluids of an infected person. Regarding knowledge of symptoms of congenital CMV, mental retardation and death were the most commonly reported clinical presentations. CONCLUSION: The current study showed that the overall knowledge of CMV is very low among women in Saudi Arabia. Working in the healthcare field and higher education levels were significantly associated with better knowledge of CMV. It is crucial that women are provided with information regarding CMV-associated complications and preventative measures against mother-to-fetus transmission of CMV.

Using Spiritual Connections to Cope With Stress and Anxiety During the COVID-19 Pandemic.

During the initial phases of the COVID-19 pandemic, stress and anxiety were pervasive among the masses due to high morbidity and mortality. Besides the fear of coronavirus was also particularly driven by social media. Many people started to look for faith and spiritual connections to gain comfort. The role of spiritual ties and religious beliefs in relation to coping with pandemic stress has acquired the attention of researchers in some parts of the world. This cross-sectional survey aimed at assessing the intensity of stress and anxiety symptoms experienced by people and how much they were alleviated by employing spiritual connections. The study sample comprises 795 respondents with 52% males and 48% females living in Saudi Arabia. The brief online study questionnaire collected data about background variables, anxiety and stress scale from DASS-21, and items from the WHOQOL (SRBP) instrument assessed the use of spiritual beliefs to cope. Multiple regression models were tested to determine the role of spiritual connections after adjusting demographic variables. Results illustrated that after adjusting for gender and age, participants' anxiety symptoms decreased by (ß = -0.27; p = 0.000) units with each unit increase in the use of spiritual connections, and participants' stress symptoms reduce by (ß = -0.36; p = 0.000) units with each unit increase in coping with spirituality. Additionally, females' risk to experience anxiety and stress symptoms was more than males [(ß = 0.88; p = 0.01) and (ß = 0.92; p = 0.000)], respectively. An increase in age decreases the likelihood of experiencing anxiety symptoms and stress symptoms by (ß = -0.75; p = 0.02) and (ß = -0.11; p = 0.000) units, respectively. Findings support the protective role of spiritual connections despite small beta coefficients. The social and cultural context in Saudi Arabia favors deep-rooted connections with spirituality and faith. Our findings support the fact that the reliance on spiritual connections helped older people to deal with exaggerated fear during the initial phase of the COVID-19 pandemic and reduces the risk of experiencing anxiety and stress symptoms. Females and younger participants were relatively vulnerable to developing these symptoms. We discussed these findings considering some recent studies that reported similar relationships and made recommendations for future research.

Short- and Long-Term Self-Reported Audiovestibular Symptoms of SARS-CoV-2 Infection in Hospitalized and Nonhospitalized Patients.

BACKGROUND: Audiovestibular symptoms during the acute stage have been reported in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), while very few studies investigated the long-term audiovestibular manifestations of SARS-CoV-2. OBJECTIVE: The objective of this study was to examine the occurrence of short- and long-term audiovestibular symptoms associated with SARS-CoV-2 infection. METHOD: In this cross-sectional study, a questionnaire was distributed to severe hospitalized cases and nonhospitalized patients with mild disease, all with confirmed SARS-CoV-2 test results. Participants were inquired to report audiovestibular symptoms during the acute phase and at 6-month follow-up after contracting SARS-CoV-2. RESULTS: A total of 301 participants completed the questionnaire. Auditory symptoms were reported by 21.9% and 1.99% of patients during the acute phase and 6 months post SARS-CoV-2 infection, respectively. During the acute phase of SARS-CoV-2 infection, aural fullness represents the most common symptoms (18.94%) followed by tinnitus (9.97%) and hearing loss (6.31%). Vestibular symptoms were reported by 34% during the acute phase; most commonly was dizziness (29.9%) followed by vertigo (24.25%) and unsteadiness (8.31%). Long-term and persistent vestibular problems were reported by 3.99% patients. There were no statistically significant differences in self-reported audiovestibular symptoms between patients with severe SARS-CoV-2 disease compared to those with mild disease. CONCLUSION: The current study showed that audiovestibular symptoms are common among SARS-CoV-2 infected patients during the acute phase of the disease. However, these symptoms are mostly temporary and showed complete spontaneous recovery during the first 2 weeks postinfection.

Prevalence, risk factors, and audiological characteristics of auditory neuropathy.

OBJECTIVE: The objective of this study was to determine the prevalence, risk factors, and audiological characteristics of auditory neuropathy spectrum disorder (ANSD) in the pediatric population. DESIGN: A retrospective review of medical charts was conducted for children visiting two hospitals in Saudi Arabia. STUDY SAMPLE: Medical records of 1025 patients with sensorineural hearing loss (SNHL) were reviewed. We analyzed the databases for results of audiological examinations, risk factors, and outcomes of intervention including hearing aid (HA) and cochlear implantation (CI). RESULTS: Out of 1025 children with SNHL, 101 patients (9.85%) were identified to have ANSD. Audiological characteristics of the ANSD group revealed a severe-to-profound degree of hearing loss, all showed type A tympanogram and absent reflexes, absent auditory brainstem response (ABR) findings with present cochlear microphonic while otoacoustic emissions were absent in 54.5% of patients. The most prevalent risk factors for ANSD in this group were family history of hearing loss, consanguinity, hyperbilirubinemia, and low birth weight. Pure tone and speech detection thresholds improved significantly with CI compared to HA use in this sample of patients with ANSD. CONCLUSION: This study shows that ANSD is not extremely rare among Saudi children with severe to profound hearing loss, with a prevalence of 9.85%.

The Impact of Extended E-Learning on Emotional Well-Being of Students during the COVID-19 Pandemic in Saudi Arabia.

Educational institutions in Saudi Arabia extended e-learning until the third semester of the academic calendar to prevent the spread of COVID-19 infection and to achieve 70% inoculation for the Saudi population. This study assesses the impact of extended e-learning and other associated stressors on the emotional health of university students in Saudi Arabia. An online cross-sectional survey collected data between the months of January-March 2021. The emotional signs of stress were measured by using a subset of items from the COVID-19 Adolescent Symptom and Psychological Experience Questionnaire (CASPE). Data about demographic variables, educational characteristics and academic performance were also collected. A regression analysis was performed to determine predictors of emotional health. A total of 434 university students including females (63%) and males (37%) provided responses. One-third of students (33%) indicated that the COVID-19 pandemic and its resulting changes including online distance studies greatly influenced their daily lives in a negative way. The regression analysis demonstrated that female students and students with average academic performance had increased vulnerability to experience emotional signs of stress (p < 0.05). The factors 'Not going to university' and 'Not having a routine life' were significant predictors of stress responses (p < 0.01) and (p < 0.001) respectively. E-learning during the COVID-19 pandemic made it possible for students to complete their studies as per academic calendar; simultaneously, it increased the vulnerability to experience stress, particularly for female students and students with average academic performance. These findings imply that academic advising and counseling services should be more readily available during digital studies to support at risk students.

Role of cochlear synaptopathy in cytomegalovirus infected mice and in children.

OBJECTIVES: Determine whether a murine model of cytomegalovirus (CMV) and CMV- infected children show evidence of synaptopathy. STUDY DESIGN: Murine model of CMV infection and case series. SUBJECTS AND METHODS: C57 BL/6 mice were inoculated with murine-CMV (mCMV). Auditory function was assessed using Auditory Brainstem Response (ABR) and distortion product otoacoustic emission (DPOAE) testing. Temporal bones from mCMV-infected mice were used for both ribbon synapse and hair cell quantification. Four groups of children (non-CMV normal hearing, non-CMV hearing impaired, CMV normal hearing and CMV hearing impaired) underwent ABRs between 2014 and 2018. The outcomes included raw amplitude, wave I:V amplitude ratio, absolute latency, and interpeak latency. RESULTS: Mice at 8 weeks post mCMV infection had higher ABR and DPOAE (P < 0.05) thresholds and increased outer hair cell loss compared to uninfected mice and mCMV-infected mice at 4 and 6 weeks post infection, indicating progressive hearing loss. A reduction in the wave I amplitude and synaptic counts were noted earlier at 4 weeks in CMV-infected mice (P < 0.05). The human data indicated that the wave I:V amplitude ratio was lower on average in CMV-infected groups when compared to the uninfected cohorts. The wave I:V amplitude ratio for the click and 4k stimuli were not significantly different between the congenital CMV-infected and uninfected children with normal or with hearing loss. CONCLUSION: This study suggests mCMV infection results in a synaptopathy before hair cell damage. Additional studies need to be performed to determine whether this effect is also observed in CMV-infected children. LEVEL OF EVIDENCE: Animal studies and basic science- NA; human studies: level 4.

Role of Free Radical Formation in Murine Cytomegalovirus-Induced Hearing Loss.

OBJECTIVES: The goal of the study was to determine whether reactive oxygen species (ROS) mediates cytomegalovirus (CMV)-induced labyrinthitis. STUDY DESIGN: Murine model of CMV infection. SETTING: University of Utah laboratory. SUBJECTS AND METHODS: Nrf2 knockout mice were inoculated with murine CMV. Auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs) were then performed on these and uninfected controls. BALB/c mice were inoculated with murine CMV to determine whether a marker for ROS production, dihydroethidium (DHE), is expressed 7 days after inoculation. Finally, 2 antioxidants-D-methionine and ACE-Mg (vitamins A, C, and E with magnesium)-were administered 1 hour before and after infection in inoculated mice for 14 days. Temporal bones were harvested at postnatal day 10 for DHE detection. ABR and DPOAE testing was done at postnatal day 30. Scanning electron microscopy was also performed at postnatal day 30 to evaluate outer hair cell integrity. RESULTS: Nrf2-infected mice had worse hearing than uninfected mice (P < .001). A statistically significant increase in DHE fluorescence was detected in BALB/c-infected mice as compared with uninfected mice 7 days after inoculation. D-methionine- and ACE-Mg-treated mice demonstrated an attenuation of the DHE fluorescence and a significant improvement in ABR and DPOAE thresholds when compared with untreated infected controls (P < .0001). Scanning electron microscopy demonstrated less outer hair cell loss in the treated versus untreated infected controls. CONCLUSION: These results demonstrate for the first time that excessive ROS mediates CMV-induced hearing loss in a mouse model.

The release of surface-anchored α-tectorin, an apical extracellular matrix protein, mediates tectorial membrane organization.

The tectorial membrane (TM) is an apical extracellular matrix (ECM) that hovers over the cochlear sensory epithelium and plays an essential role in auditory transduction. The TM forms facing the luminal endolymph-filled space and exhibits complex ultrastructure. Contrary to the current extracellular assembly model, which posits that secreted collagen fibrils and ECM components self-arrange in the extracellular space, we show that surface tethering of α-tectorin (TECTA) via a glycosylphosphatidylinositol anchor is essential to prevent diffusion of secreted TM components. In the absence of surface-tethered TECTA, collagen fibrils aggregate randomly and fail to recruit TM glycoproteins. Conversely, conversion of TECTA into a transmembrane form results in a layer of collagens on the epithelial surface that fails to form a multilayered structure. We propose a three-dimensional printing model for TM morphogenesis: A new layer of ECM is printed on the cell surface concomitant with the release of a preestablished layer to generate the multilayered TM.

Natural killer cells attenuate cytomegalovirus-induced hearing loss in mice.

Congenital cytomegalovirus (CMV) infection is the most common non-hereditary cause of sensorineural hearing loss (SNHL) yet the mechanisms of hearing loss remain obscure. Natural Killer (NK) cells play a critical role in regulating murine CMV infection via NK cell recognition of the Ly49H cell surface receptor of the viral-encoded m157 ligand expressed at the infected cell surface. This Ly49H NK receptor/m157 ligand interaction has been found to mediate host resistance to CMV in the spleen, and lung, but is much less effective in the liver, so it is not known if this interaction is important in the context of SNHL. Using a murine model for CMV-induced labyrinthitis, we have demonstrated that the Ly49H/m157 interaction mediates host resistance in the temporal bone. BALB/c mice, which lack functional Ly49H, inoculated with mCMV at post-natal day 3 developed profound hearing loss and significant outer hair cell loss by 28 days of life. In contrast, C57BL/6 mice, competent for the Ly49H/m157 interaction, had minimal hearing loss and attenuated outer hair cell loss with the same mCMV dose. Administration of Ly49H blocking antibody or inoculation with a mCMV viral strain deleted for the m157 gene rendered the previously resistant C57BL/6 mouse strain susceptible to hearing loss to a similar extent as the BALB/c mouse strain indicating a direct role of the Ly49H/m157 interaction in mCMV-dependent hearing loss. Additionally, NK cell recruitment to sites of infection was evident in the temporal bone of inoculated susceptible mouse strains. These results demonstrate participation of NK cells in protection from CMV-induced labyrinthitis and SNHL in mice.

Notched-noise precursors improve detection of low-frequency amplitude modulation.

Amplitude modulation (AM) detection was measured with a short (50 ms), high-frequency carrier as a function of carrier level (Experiment I) and modulation frequency (Experiment II) for conditions with or without a notched-noise precursor. A longer carrier (500 ms) was also included in Experiment I. When the carrier was preceded by silence (no precursor condition) AM detection thresholds worsened for moderate-level carriers compared to lower- or higher-level carriers, resulting in a "mid-level hump." AM detection thresholds with a precursor were better than those without a precursor, primarily for moderate-to-high level carriers, thus eliminating the mid-level hump in AM detection. When the carrier was 500 ms, AM thresholds improved by a constant (across all levels) relative to AM thresholds with a precursor, consistent with the longer carrier providing more "looks" to detect the AM signal. Experiment II revealed that improved AM detection with compared to without a precursor is limited to low-modulation frequencies (<60 Hz). These results are consistent with (1) a reduction in cochlear gain over the course of the precursor perhaps via the medial olivocochlear reflex or (2) a form of perceptual enhancement which may be mediated by adaptation of inhibition.

Cytomegalovirus (CMV) Infection Causes Degeneration of Cochlear Vasculature and Hearing Loss in a Mouse Model.

Cytomegalovirus (CMV) infection is one of the most common causes of congenital hearing loss in children. We have used a murine model of CMV infection to reveal functional and structural cochlear pathogenesis. The cerebral cortex of Balb/c mice (Mus musculus) was inoculated with 2000 pfu (plaque forming units) of murine CMV on postnatal day 3. At 6 weeks of age, cochlear function was monitored using auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) measures. Histological assessment of cochlear vasculature using a corrosion cast technique was made at 8 weeks. Vascular casts of mCMV-damaged cochleas, and those of untreated control animals, were examined using scanning electron microscopy. We find very large variations in the degree of vascular damage in animals given identical viral injections (2000 pfu). The primary lesion caused by CMV infection is to the stria vascularis and to the adjacent spiral limbus capillary network. Capillary beds of the spiral ligament are generally less affected. The initial vascular damage is found in the mid-apical turn and appears to progress to more basal cochlear regions. After viral migration to the inner ear, the stria vascularis is the primary affected structure. We suggest that initial auditory threshold losses may relate to the poor development or maintenance of the endocochlear potential caused by strial dysfunction. Our increased understanding of the pathogenesis of CMV-related hearing loss is important for defining methods for early detection and treatment.

The roles of USH1 proteins and PDZ domain-containing USH proteins in USH2 complex integrity in cochlear hair cells.

Usher syndrome (USH) is the most common cause of inherited deaf-blindness, manifested as USH1, USH2 and USH3 clinical types. The protein products of USH2 causative and modifier genes, USH2A, ADGRV1, WHRN and PDZD7, interact to assemble a multiprotein complex at the ankle link region of the mechanosensitive stereociliary bundle in hair cells. Defects in this complex cause stereociliary bundle disorganization and hearing loss. The four USH2 proteins also interact in vitro with USH1 proteins including myosin VIIa, USH1G (SANS), CIB2 and harmonin. However, it is unclear whether the interactions between USH1 and USH2 proteins occur in vivo and whether USH1 proteins play a role in USH2 complex assembly in hair cells. In this study, we identified a novel interaction between myosin VIIa and PDZD7 by FLAG pull-down assay. We further investigated the role of the above-mentioned four USH1 proteins in the cochlear USH2 complex assembly using USH1 mutant mice. We showed that only myosin VIIa is indispensable for USH2 complex assembly at ankle links, indicating the potential transport and/or anchoring role of myosin VIIa for USH2 proteins in hair cells. However, myosin VIIa is not required for USH2 complex assembly in photoreceptors. We further showed that, while PDZ protein harmonin is not involved, its paralogous USH2 proteins, PDZD7 and whirlin, function synergistically in USH2 complex assembly in cochlear hair cells. In summary, our studies provide novel insight into the functional relationship between USH1 and USH2 proteins in the cochlea and the retina as well as the disease mechanisms underlying USH1 and USH2.

Individual USH2 proteins make distinct contributions to the ankle link complex during development of the mouse cochlear stereociliary bundle.

Usher syndrome (USH) is the leading cause of inherited deaf-blindness, with type 2 (USH2) being the most common clinical form. Studies suggest that proteins encoded by USH2 causative genes assemble into the ankle link complex (ALC) at the hair cell stereociliary bundle; however, little is known about the in vivo assembly and function of this complex. Using various USH2 mutant mice, we showed by immunofluorescence that USH2 proteins play different roles in cochlear ALC assembly, with G protein-coupled receptor 98 being the most important protein. Complex assembly likely occurs at the stereociliary bundle but not along the protein transport route in the cell body. Stereociliary morphological defects in USH2 mutant mice suggest roles for the ALC in regulating inner hair cell stereociliary growth and differentiation as well as outer hair cell stereociliary rigidity and organization during development. These roles are unique from the bundle cohesion role of Usher syndrome type 1 protein complexes. Loss of individual USH2 gene expressions leads to variable morphological and functional consequences, correlating with the severity of ALC disruption. This finding suggests a potential genotype-phenotype correlation in USH2 patients. In summary, this study provides novel insights into the molecular mechanism underlying cochlear stereociliary bundle development and hearing loss pathogenesis of various USH2 subtypes. Our thorough phenotypical characterization of USH2 mouse models is essential for future use of these animal models in therapeutic development.

Distinct expression and function of whirlin isoforms in the inner ear and retina: an insight into pathogenesis of USH2D and DFNB31.

Usher syndrome (USH) is the most common inherited deaf-blindness with the majority of USH causative genes also involved in nonsyndromic recessive deafness (DFNB). The mechanism underlying this disease variation of USH genes is unclear. Here, we addressed this issue by investigating the DFNB31 gene, whose mutations cause USH2D or DFNB31 depending on their position. We found that the mouse DFNB31 ortholog (Dfnb31) expressed different mRNA variants and whirlin protein isoforms in the cochlea and retina, where these isoforms played different roles spatially and temporally. Full-length (FL-) whirlin in photoreceptors and hair cell stereociliary bases is important for the USH type 2 protein complex, while FL- and C-terminal (C-) whirlins in hair cell stereociliary tips participate in stereociliary elongation. Mutations in the whirlin N-terminal region disrupted FL-whirlin isoform in the inner ear and retina but not C-whirlin in the inner ear, and led to retinal degeneration as well as moderate to severe hearing loss. By contrast, a mutation in the whirlin C-terminal region eliminated all normal whirlin isoforms but generated a truncated N-terminal whirlin protein fragment, which was partially functional in the retina and thus prevented retinal degeneration. Mice with this mutation had profound hearing loss. In summary, disruption of distinct whirlin isoforms by Dfnb31 mutations leads to a variety of phenotype configurations and may explain the mechanism underlying the different disease manifestations of human DFNB31 mutations. Our findings have a potential to improve diagnosis and treatment of USH disease and quality of life in USH patients.