The otolith organs play a critical role in detecting linear acceleration and gravity to control posture and balance. Some afferents that innervate these structures can be activated by sound and are ...at risk for noise overstimulation. A previous report demonstrated that noise exposure can abolish vestibular short-latency evoked potential (VsEP) responses and damage calyceal terminals. However, the stimuli that were used to elicit responses were weaker than those established in previous studies and may have been insufficient to elicit VsEP responses in noise-exposed animals. The goal of this study was to determine the effect of an established noise exposure paradigm on VsEP responses using large head-jerk stimuli to determine if noise induces a stimulus threshold shift and/or if large head-jerks are capable of evoking VsEP responses in noise-exposed rats. An additional goal is to relate these measurements to the number of calyceal terminals and hair cells present in noise-exposed vs. non-noise-exposed tissue. Exposure to intense continuous noise significantly reduced VsEP responses to large stimuli and abolished VsEP responses to small stimuli. This finding confirms that while measurable VsEP responses can be elicited from noise-lesioned rat sacculi, larger head-jerk stimuli are required, suggesting a shift in the minimum stimulus necessary to evoke the VsEP. Additionally, a reduction in labeled calyx-only afferent terminals was observed without a concomitant reduction in the overall number of calyces or hair cells. This finding supports a critical role of calretinin-expressing calyceal-only afferents in the generation of a VsEP response.
This study identifies a change in the minimum stimulus necessary to evoke vestibular short-latency evoked potential (VsEP) responses after noise-induced damage to the vestibular periphery and reduced numbers of calretinin-labeled calyx-only afferent terminals in the striolar region of the sacculus. These data suggest that a single intense noise exposure may impact synaptic function in calyx-only terminals in the striolar region of the sacculus. Reduced calretinin immunolabeling may provide insight into the mechanism underlying noise-induced changes in VsEP responses.
Despite our understanding of the impact of noise-induced damage to the auditory system, much less is known about the impact of noise exposure on the vestibular system. In this article, we review the ...anatomical, physiological, and functional evidence for noise-induced damage to peripheral and central vestibular structures. Morphological studies in several animal models have demonstrated cellular damage throughout the peripheral vestibular system and particularly in the otolith organs; however, there is a paucity of data on the effect of noise exposure on human vestibular end organs. Physiological studies have corroborated morphological studies by demonstrating disruption across vestibular pathways with otolith-mediated pathways impacted more than semicircular canal-mediated pathways. Similar to the temporary threshold shifts observed in the auditory system, physiological studies in animals have suggested a capacity for recovery following noise-induced vestibular damage. Human studies have demonstrated that diminished sacculo-collic responses are related to the severity of noise-induced hearing loss, and dose-dependent vestibular deficits following noise exposure have been corroborated in animal models. Further work is needed to better understand the physiological and functional consequences of noise-induced vestibular impairment in animals and humans.
Neural probes are micromachined multichannel electrode arrays that facilitate the functional stimulation and recording of neurons in the peripheral and central nervous system. For long-term ...implantations, surface modification is necessary for maintaining the stable connection between electrodes and neurons. The conductive polymer polypyrrole (PPy) and synthetic peptide DCDPGYIGSR were co-deposited on the electrode surface by electrochemical polymerization. The stability of PPy/DCDPGYIGSR coatings was tested in soaking experiments. It was found that the peptide was entrapped in the PPy film and did not diffuse away within 7 weeks of soaking in DI water. Coated probes were implanted in guinea pig brain for periods of 1, 2 and 3 weeks. Recording tests were performed and the impedance was monitored. The explanted probes and tissue were examined by immunocytochemical studies. Significantly more neurofilament positive staining was found on the coated electrode which indicated that the coatings had established strong connections with the neuronal structure in vivo. Good recordings were obtained from the coated sites that had neurons attached. First week tissue sections had no significant gliosis. In week 2, a layer of non-neuronal tissue consisting of mostly meningeal fibroblasts and ECM protein including at least fibronectin was formed around the probe tracks of both coated and uncoated probes. Astrocytes started to form a loosely organized layer by the end of the third week.
Our previous study demonstrated rapamycin added to diet at 4 months of age had significantly less age-related outer hair cell loss in the basal half of the cochlea at 22 months of age compared to ...mice without rapamycin. The present study tested adding rapamycin to diet later in life, at 14 months of age, and added a longitudinal assessment of auditory brain stem response (ABR). The present study used UMHET4 mice, a 4 way cross in which all grandparental strains lack the Cdh23
allele that predisposes to early onset, progressive hearing loss. UMHET4 mice typically have normal hearing until 16-17 months, then exhibit threshold shifts at low frequencies/apical cochlea and later in more basal high frequency regions. ABR thresholds at 4, 12, 24, and 48 kHz were assessed at 12, 18, and 24 months of age and compared to baseline ABR thresholds acquired at 5 months of age to determine threshold shifts (TS). There was no TS at 12 months of age at any frequency tested. At 18 months of age mice with rapamycin added to diet at 14 months had a significantly lower mean TS at 4 and 12 kHz compared to mice on control diet with no significant difference at 24 and 48 kHz. At 24 months of age, the mean 4 kHz TS in rapamycin diet group was no longer significantly lower than the control diet group, while the 12 kHz mean remained significantly lower. Mean TS at 24 and 48 kHz in the rapamycin diet group became significantly lower than in the control diet group at 24 months. Hair cell counts at 24 months showed large loss in the apical half of most rapamycin and control diet mice cochleae with no significant difference between groups. There was only mild outer hair cell loss in the basal half of rapamycin and control diet mice cochleae with no significant difference between groups. The results show that a later life addition of rapamycin can decrease age-related hearing loss in the mouse model, however, it also suggests that this decrease is a delay/deceleration rather than a complete prevention.
Aims
To evaluate the effectiveness of automated symptom and side effect monitoring on quality of life among individuals with symptomatic diabetic peripheral neuropathy.
Methods
We conducted a ...pragmatic, cluster randomized controlled trial (July 2014 to July 2016) within a large healthcare system. We randomized 1834 primary care physicians and prospectively recruited from their lists 1270 individuals with neuropathy who were newly prescribed medications for their symptoms. Intervention participants received automated telephone‐based symptom and side effect monitoring with physician feedback over 6 months. The control group received usual care plus three non‐interactive diabetes educational calls. Our primary outcomes were quality of life (EQ‐5D) and select symptoms (e.g. pain) measured 4–8 weeks after starting medication and again 8 months after baseline. Process outcomes included receiving a clinically effective dose and communication between individuals with neuropathy and their primary care provider over 12 months. Interviewers collecting outcome data were blinded to intervention assignment.
Results
Some 1252 participants completed the baseline measures mean age (sd): 67 (11.7), 53% female, 57% white, 8% Asian, 13% black, 20% Hispanic. In total, 1179 participants (93%) completed follow‐up (619 control, 560 intervention). Quality of life scores (intervention: 0.658 ± 0.094; control: 0.653 ± 0.092) and symptom severity were similar at baseline. The intervention had no effect on primary EQ‐5D: −0.002 (95% CI −0.01, 0.01), P = 0.623; pain: 0.295 (−0.75, 1.34), P = 0.579; sleep disruption: 0.342 (−0.18, 0.86), P = 0.196; lower extremity functioning: −0.079 (−1.27, 1.11), P = 0.896; depression: −0.462 (−1.24, 0.32); P = 0.247 or process outcomes.
Conclusions
Automated telephone monitoring and feedback alone were not effective at improving quality of life or symptoms for people with symptomatic diabetic peripheral neuropathy.
Trial Registration: ClinicalTrials.gov (NCT02056431).
What's new?
Frequent communication between individuals with diabetic peripheral neuropathy and primary care providers about symptoms and medication side effects is critical to optimizing medication dosing to treat painful diabetic peripheral neuropathy. Yet, there are considerable barriers to effective communication.
This cluster randomized controlled trial found that a brief intervention to automatically monitor person‐reported data on symptoms and side effects, and provide the information to physicians via an electronic health record was not effective in improving the outcomes valued by individuals with neuropathy.
Alerts alone are unlikely to change provider behaviour related to treatment intensification. More intensive interventions focused on individual activation or provider education may be more effective in changing prescribing behaviour and improving outcomes.
Highlights • Loss of inner hair cell–auditory nerve connections precedes hair cell loss in most of the cochlea. • Loss of gap detection precedes hair cell loss in the basal two-thirds of the cochlea. ...• Loss of connections may contribute to but does not account for all of the age-related reduced gap detection. • Decrease in Ntf3 expression occurs at the same time as loss of inner hair cell–auditory nerve connections. • Hair cell loss and ABR thresholds increase significantly from 22–24 months to 27–29 months of age.
Structure and innervation of the cochlea Raphael, Yehoash; Altschuler, Richard A
Brain Research Bulletin,
06/2003, Letnik:
60, Številka:
5
Book Review, Journal Article
Recenzirano
The role of the cochlea is to transduce complex sound waves into electrical neural activity in the auditory nerve. Hair cells of the organ of Corti are the sensory cells of hearing. The inner hair ...cells perform the transduction and initiate the depolarization of the spiral ganglion neurons. The outer hair cells are accessory sensory cells that enhance the sensitivity and selectivity of the cochlea. Neural feedback loops that bring efferent signals to the outer hair cells assist in sharpening and amplifying the signals. The stria vascularis generates the endocochlear potential and maintains the ionic composition of the endolymph, the fluid in which the apical surface of the hair cells is bathed. The mechanical characteristics of the basilar membrane and its related structures further enhance the frequency selectivity of the auditory transduction mechanism. The tectorial membrane is an extracellular matrix, which provides mass loading on top of the organ of Corti, facilitating deflection of the stereocilia. This review deals with the structure of the normal mature mammalian cochlea and includes recent data on the molecular organization of the main cell types within the cochlea.
Adding rapamycin or acarbose to diet at 9–10 months of age has been shown to significantly increase life span in both male and female UM-HET3 mice. The current study examined cochleae of male and ...female UM-HET3 mice at 22 months of age to determine if either treatment also influenced age-related loss of cochlear hair cells. A large loss of cochlear outer hair cells was observed at 22 months of age in untreated mice in both apical and basal halves of the cochlear spiral. Addition of acarbose to diet had no significant effect on the amount of outer hair cell loss at 22 months of age or in its pattern, with large loss in both apical and basal halves. The addition of rapamycin to diet, however, significantly reduced outer hair cell loss in the basal half of the cochlea at 22 months of age when compared to untreated mice. There was no significant difference between male and female mice in any of the conditions. Age-related outer hair cell loss in the apical cochlea precedes outer hair cell loss in the base in many mouse strains. The results of the present study suggest that rapamycin but not acarbose treatment can delay age-related loss of outer hair cells at doses at which each drug increases life span.
•Adding rapamycin to diet at 4 months decreased hair cell loss in 22 month old mice.•Decreased age-related hair cell loss with rapamycin was in basal half of the cochlea.•Adding acarbose to diet did not decrease hair cell loss in 22 month old mice.
OBJECTIVE:--The purpose of this study was to determine the effect of cinnamon on glycemic control in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS--Using a prospective, double-blind, ...placebo-controlled design, 72 adolescent type 1 diabetic subjects were treated in an outpatient setting with cinnamon (1 g/day) or an equivalent-appearing placebo for 90 days. A1C, total daily insulin intake, and adverse events were recorded and compared between groups. RESULTS:--There were no significant differences in final A1C (8.8 vs. 8.7, P = 0.88), change in A1C (0.3 vs. 0.0, P = 0.13), total daily insulin intake, or number of hypoglycemic episodes between the cinnamon and placebo arms. CONCLUSIONS:--Cinnamon is not effective for improving glycemic control in adolescents with type 1 diabetes.
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