Hyaluronan up-regulation is linked to renal dysfunction and hearing loss induced by silver nanoparticles

Increased application of silver nanoparticles (AgNPs) has raised concerns on their potential adverse effects on human health. However, the precise toxicological mechanisms are not known in detail. The current study hypothesized that AgNPs induced glycosaminoglycan accumulation in the basement membrane that associated with the up-regulation of its component hyaluronic acid, known as a hydrophilic molecule of binding and retaining water, and caused toxicities in the kidney and cochlea. Rats administered AgNPs through either intravenous or intratympanic injection were observed at different time points after exposure. The concentrations of creatinine and urea in the serum were elevated remarkably, and proteins leaked into the urine were increased. A significant hearing loss over a broad range of frequencies was indicated. AgNP exposure induced glycosaminoglycan accumulation and hyaluronic acid up-regulation in the basement membrane. Abundant apoptotic cell death was demonstrated in the AgNP-exposed organs. Our results suggested that glycosaminoglycan accumulation associated with the up-regulation of hyaluronic acid was involved in the toxicities of kidney and cochlea caused by AgNPs.

Pathway and morphological transformation of liposome nanocarriers after release from a novel sustained inner-ear delivery system

Aim: To validate a novel sustained delivery system of liposome nanocarriers for inner-ear therapy and to investigate the transport pathway for their delivery. Materials & methods: Liposome nanocarriers containing gadolinium-tetra-azacyclo-dodecane-tetra-acetic acid (LPS+Gd-DOTA) were developed for MRI tracking the in vitro release profile and for in vivo uptake studies. Results: Encapsulating Gd-DOTA did not modify the liposomes. The LPS+Gd-DOTA nanocarriers were slowly released from a miniature osmotic pump. The LPS+Gd-DOTA moved along the ossicular chain toward the oval window after an epitympanic injection, whereas they traveled directly to the round window after a mesotympanic injection. However, the round window membrane was the major pathway for the LPS+Gd-DOTA to enter the inner ear. LPS+Gd-DOTA were visualized on both sides of the cochlea within 6 days of in vivo delivery via the osmotic pump. Discussion: The novel sustained inner-ear delivery system induced liposome nanocarriers into the inner ear efficiently without causing obvious adverse effect. There is the potential of using the system to administrate therapeutics in treating inner-ear diseases in the clinic.

Original submitted 25 April 2013; Revised submitted 3 September 2013

The sense of coherence in patients with Menière's disease

OBJECTIVE

To investigate how the ability to adapt, measured by the sense of coherence (SOC), is related to specific complaints of Menière's disease (MD) and the disease specific and general health related quality of life (EQ-5D) and on disease specific impact of the disease (MD-impact).

METHODS

Postal survey, including a structured questionnaire on EQ-5D, SOC, symptoms, positive experiences, and the impact of MD, was sent to the members of the Finnish Menière Federation, reporting a diagnosis compatible with the condition. A sample of 547 members replied and were analyzed.

RESULTS

The SOC reflected the disabilities caused by symptoms of MD and psychosocial factors including verbal score scale (VSS) anxiety (p<0.01) and loss of vitality (p<0.001). Higher SOC scores were related to better scores in EQ-5D and lower scores in MD-impact. Positive attitudes consequential to MD were associated with higher SOC scores reflecting better control over the consequences of disease.

CONCLUSION

SOC is an element of patient's attitude toward illness and correlates with perceived good health. Patients with higher SOC scores are more content with their quality of life. Future research should focus on whether influencing modifiable psychological factors, such as positive attitudes, could improve adaptive ability in MD.

Feasibility of force platform based roadside drowsiness screening - a pilot study

Previous research on driver drowsiness detection has focused on developing in-car systems that continuously monitor the driver while driving and warn him/her when drowsiness compromises safety. In occupational settings a simple test of postural control has showed sensitivity to work shift induced fatigue in drivers. Whether the test is feasible for surveillance purposes in roadside settings is unknown. The present research sought to evaluate the feasibility of using a force platform test of postural control as a breathalyzer-like drowsiness-test at the roadside. Seventy-one commercial drivers stopped by at our measurement sites and volunteered to participate in the study. We tested postural control with a computerized force platform, on which the drivers stood eyes open while it sampled body center-of-pressure excursions at 33Hz for 30s and scored postural control as the area of the 95% confidence ellipse enclosing the excursions. The drivers also completed the Karolinska Sleepiness Scale (KSS) and we recorded each driver's wake up time, time on task, and time of testing. Five of the seventy-one drivers exhibited significantly poorer postural control than their peers (P=0.03). The wake up times and times on task for these five drivers indicated that they were on a night shift schedule or had a long time on task. Furthermore, their postural control and KSS scores correlated (r=-0.88, P=0.04), whereas the scores did not correlate for their peers (r=0.10, P=0.48). These results indicate that the force platform test identified drivers, whose impairment in postural control was drowsiness-related. Specifically, the test identified the few drivers in this roadside sample whose wake- and work histories resembled a night shift schedule. In this kind of roadside setting, with a demographically heterogeneous group and interindividual differences in people's responses to drowsiness, it suggests that the method, further developed, may provide a drowsiness test for roadside surveillance.

Postural stability and quality of life after guided and self-training among older adults residing in an institutional setting

Purpose

To evaluate whether rehabilitation of muscle force or balance improves postural stability and quality of life (QoL), and whether self-administered training is comparable with guided training among older adults residing in an institutional setting.

Patients and methods

A randomized, prospective intervention study was undertaken among 55 elderly patients. Three intervention groups were evaluated: a muscle force training group; a balance and muscle force training group; and a self-administered training group. Each group underwent 1-hour-long training sessions, twice a week, for 3 months. Postural stability was measured at onset, after 3 months, and after 6 months. Time-domain-dependent body sway variables were calculated. The fall rate was evaluated for 3 years. General health related quality of life (HRQoL) was measured with a 15D instrument. Postural stability was used as a primary outcome, with QoL and falls used as secondary outcomes.

Results

Muscle force trainees were able to undertake training, progressing towards more strenuous exercises. In posturography, the number of spiky oscillations was reduced after training, and stationary fields of torque moments of the ankle increased, providing better postural stability in all groups; in particular, the zero crossing rate of weight signal and the number of low variability episodes in the stabilogram were improved after training. While no difference was found between different training groups in posturography outcomes, a reduction of fall rate was significant in only the guided training groups. A significant part of the variability of the QoL could be explained by the posturography outcome (46%). However, the outcome of training was associated with a reduced QoL.

Conclusion

Even moderate or severely demented residents could do exercises in five-person groups under the supervision of a physiotherapist. An improvement in postural stability was observed in all training groups, indicating that even self-administered training could be beneficial. Posturography outcome indicated that training alters the postural strategy by reducing the oscillatory fluctuations of body sway signal. However, only guided training tended to reduce falls. Short training intervention programs may decrease QoL by changing the elderly’s daily routine and making it more active and exhausting.

Multifunctional nanoprobe for MRI/optical dual-modality imaging and radical scavenging

The development of novel nanomaterials for the diagnosis and/or treatment of human diseases has become an important issue. In this work, a multifunctional theranostic agent was designed by covalently binding hydroxyl- and amino-bearing C60 derivatives (C60 O∼10 (OH)∼16 (NH2 )∼6 (NO2 )∼6 ⋅24 H2 O) with gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) to yield C60 O∼10 (OH)∼16 (NH2 )∼6 (NO2 )∼6 ⋅24 H2 O/(Gd-DTPA)3 (DF1 Gd3 ). The obtained DF1 Gd3 shows more than fourfold contrast improvement over commercial Gd-DTPA along with multiwavelength fluorescent emission for dual-modality diagnosis. An inner-ear magnetic resonance imaging (MRI) study was designed as a model of biological barriers, including the blood/brain barrier (BBB) for DF1 Gd3 to investigate its in vivo behavior. This revealed that the fabricated contrast agent dramatically increases the local contrast but can not cross the middle ear/inner ear barrier and endolymph/perilymph barrier in the inner ear, and thus it is also BBB-prohibited in normal individuals. In vivo biodistribution studies suggested that 1) DF1 Gd3 could circulate in vessels for a relatively long time and is mainly eliminated through liver and kidney, 2) DF1 Gd3 may potentially function as a liver-specific MRI contrast agent. Interestingly, DF1 Gd3 also shows an excellent quenching effect on hydroxyl radicals, as revealed by the DMPO spin trap/ESR method. The combination of enhanced MRI/FL imaging and local treatment of lesions is unique to DF1 Gd3 and potentiates the medical paradigm of "detect and treat/prevent" in combating human diseases related to reactive oxygen.

Risk factors of falls in community dwelling active elderly

OBJECTIVE

To search for measures to describe and relate to accidental falls in community dwelling elderly.

METHOD

A EuroQol EQ-5D questionnaire based on a patient's otoneurological case history provided a general health related quality of life measure, a fall history for the last 3 months and force platform measures for 96 active elderly from a pensioner organization.

RESULTS

On average, the elderly experienced 0.3 falls over the preceding three months. A fall was seen to cause a significant deterioration in the quality of life and vertigo and caused fear of falling. The postural instability correlated with falls. Vertigo was present among 42% and was most commonly characterized as episodic and rotatory in factorial analysis items relating to vertigo correlated to falls and balance complaints. Four factors were identified and three of these correlated with falls. Vestibular failure correlated to a fall occurring when a person was rising up; Movement intolerance correlated with falls due to slips and trips, and Near-syncope factor correlated to falls for other reasons. In posturography, the variable measuring critical time describing the memory based "closed loop" control of postural stability carried a risk for accidental fall with an odds ratio of 6. The variable measuring zero crossing velocity showed a high rate of velocity change around the neutral position of stance.

CONCLUSION

Vertigo and poor postural stability were the major reasons for falls in the active elderly. In ageing, postural control is shifted towards open loop control (visual, proprioception, exteroception and vestibular) instead of closed loop control and is a factor that contributes to a fall.

Evaluation of the postural stability of elderly persons using time domain signal analysis

A force platform is widely used in the evaluation of postural stability in man. Although an abundance of parameters are typically retrieved from force platform data, no uniform analysis of the data has been carried out. In general, the signal analysis does not analyze the underlying postural event, i.e., whether the signal consists of several small corrections or large excursions. In the present work, we studied the postural stability of 4589 elderly persons from Iceland on a force platform under visual and non-visual conditions during stance on a solid surface. We analyzed the internal relationship between frequently used time domain variables. In addition, we conducted a factor analysis using a subset of selected variables. Factor analysis yielded three components that can be considered different strategies for maintaining posture. In one control strategy, long swaying amplitues were pronounced, allowing the person to react when postural confidence limits are reached. In a second strategy, a high oscillation rate about the stationary point was the dominant characteristic of maintaining postural control. The third strategy appears to involve a short critical time period during which an open loop control changes into a closed loop that very rapidly controls excessive postural oscillations. The findings suggest that conventional parameters such as swaying velocity and amplitude alone do not provide sufficient information regarding a person's ability to maintain an upright stance.

Clustering and summarising association rules mined from phenotype, genotype and environmental data concerning age-related hearing impairment

In this study, we examine the applicability of association rules for analysing high-dimensional data concerning age-related hearing impairment (ARHI). The ARHI data of the study contain hundreds of variables concerning phenotype, genotype and environmental factors. The number of association rules produced from the data is too large for manual exploration in the raw and furthermore, the rules are overlapping. Thus, the focus of our study is to develop an approach to cluster association rules into subsets and to summarise and represent the found rule subsets for easier exploration of rules. The results show that it is possible to efficiently extract rules representing interesting environmental factor-gene or gene-gene interactions. Finding suitable parameters for the association rule mining and the possibility to post-process the mined rules is essential. The developed approach facilitates rule exploration by grouping rules with items concerning the same phenomenon to the same subset and byrevealing overlapping rules.

Meniere's disease: a reappraisal supported by a variable latency of symptoms and the MRI visualisation of endolymphatic hydrops

OBJECTIVES

To evaluate the onset of vertigo, hearing loss and tinnitus in Ménière's disease and the associated endolymphatic hydrops (EH) of the inner ear.

DESIGN

Multicentre evaluation of three patient groups.

SETTINGS

Disease-specific symptoms were reviewed among referred patients in a tertiary referral hospital in Finland and in members of a Finnish Ménière Association in Finland. The MRI of a separate group of patients was undertaken in a tertiary referral centre in Japan.

PARTICIPANTS

340 patients were reviewed in the referral hospital along with 740 members of the Ménière Association. MRI was undertaken in 224 patients in Japan.

PRIMARY AND SECONDARY OUTCOME MEASURES

Latency and symptom development in Ménière's disease, and the appearance of EH of the inner ear in monosymptomatic patients and in Ménière's disease.

RESULTS

The mean age of the first symptom was 43.8 years, with 10% of the patients being older than 65 years. The time delay between hearing loss and vertigo was more than 5 years in 20% of the members and of the patients. Gadolinium-contrasted MRI demonstrated EH in 90% of the patients with Ménière's disease, in which 75% was bilateral among patients with unilateral symptoms. In monosymptomatic patients with vertigo, tinnitus or hearing loss; EH was demonstrated in 55-90% of the patients either in the cochlea and/or the vestibulum of the symptomatic ear.

CONCLUSIONS

Ménière's disease often shows bilateral EH and comprises a continuum from a monosymptomatic disease to the typical symptom complex of the disease. We suggest that a 3T MRI measurement should be carried out in patients with sensory-neural hearing loss, vertigo and tinnitus, 4 h after the intravenous injection of a gadolinium-contrast agent to verify the inner ear pathology. This may lead to a better management of the condition.

Mitochondria toxin-induced acute cochlear cell death indicates cellular activity-correlated energy consumption

The different cell types within the cochlea may have a specific contribution to the pathological changes during metabolism failure, which may provide clues for developing novel strategies for inner ear therapy. In order to evaluate activity-correlated cell death during metabolism failure in the cochlea, 3-nitropropionic acid was used to irreversibly inhibit the respiratory chain. Dose-response of the cochlear cells to 3-nitropropionic acid was analyzed in vitro. 3-Nitropropionic acid was administered onto the round window of guinea pigs. Cell death was identified by terminal transferase labeling the free 3'OH breaks in the DNA strands in vivo and propidium iodide nuclear permeation in vitro. As a result, 23.6 and 96.3 % cell death were induced by 10 and 100 mM 3-nitropropionic acid, respectively, in vitro. In the guinea pigs, 500 mM 3-nitropropionic acid induced vestibular dysfunction and severe to profound hearing losses. The cells that are the most sensitive to 3-nitropropionic acid treatment include the stria marginal and intermediate cells, epithelial cells of the Reissner's membrane, and spiral ligament fibrocytes (types II and V). Moderate sensitive cells were satellite fibrocytes of the spiral limbic central zone, osteocytes of the cochlear shell, hair cells, and spiral ganglion cells. Reduction of neurofilament in the soma and periphery processes of spiral ganglion cells occurred after the exposure. These results may be relevant to the mechanisms of injury in sudden onset sensorineural hearing loss and hazardous substance exposure-induced hearing loss.

Prediction of a state of a subject on the basis of a stabilogram signal and video oculography test

Postural stability decreases with ageing and may lead to accidental falls, isolation and a reduction in the quality of life. The age at the onset of postural derangement, its extent and the reason for deterioration are poorly known within an individual, but in general it becomes more severe with age. In order to prevent falls and avoid severe injuries the postural derangement has to be noticed by the person and the possible nursing personnel. In this work we propose such numerical features, which can discriminate the persons having good or poor postural stability. These features can also be utilized to measure the outcome and progression of balance training. With these postural stability algorithms providing stability features for a subject we managed to classify correctly the type of stance on the force platform in more than 80% of sixty subjects. We used k-nearest neighbor algorithm as an intuitive baseline method and compared its results with those of support vector machines and hidden Markov models.

Low-frequency sound pressure and transtympanic endoscopy of the middle ear in assessment of "spontaneous" perilymphatic fistula

This study was designed to verify an eventual perilymphatic fistula (PLF) in 264 patients with sensorineural hearing loss (SNHL) and/or vertigo. The patients were exposed to a low-frequency sound stimulation (LFS) on posturography to objectively test Tullio's phenomenon and Hennebert's sign. Endoscopes with 5 degree and 25 degree of visual angle and an outer diameter of 1.7 mm were used. The round window niche, with its foldings, oval window with stapes superstructure, a part of the facial recess and the area in the fissula ante fenestram were examined and video recorded. In one patient, we endoscopically verified a fistula in the round window membrane (resulting from a diving accident) that was covered with a fibrinous layer. In 4 cases, there was abnormal mucosal shining in the round window but without PLF. In 7 cases, the tympanic cavity could not be visualized because of the adhesive middle ear process, the abnormal anatomy, or the prominent exostoses of the ear canal prohibited vision. In 34 patients, LFS provoked unsteadiness on posturography without PLF. In 6 cases, a postoperative middle ear infection was recorded. No permanent tympanic membrane perforation occurred. It is unlikely that disease entity of “spontaneous PLF” exists. Tympanoscopy should be regarded as the first choice when a PLF is suspected.

Peptide-mediated targeting of liposomes to TrkB receptor-expressing cells

BACKGROUND

The neurotrophic receptor tyrosine kinase B (TrkB) has diverse signaling roles in neurons and tumor cells. Accordingly, its suppressive targeting is of interest in neuroblastoma and other tumors, whereas its role in improving survival is focused in neurons. Here we describe targeting of TrkB-binding peptide-conjugated liposomes (PCL) to the TrkB-expressing mouse macrophage-like cell line RAW264, and to all-trans-retinoic acid-treated neuron-like TrkB⁺ SH-SY5Y human neuroblastoma cells.

METHODS

Binding and internalization of PCL was monitored by flow cytometry and confocal fluorescence microscopy.

RESULTS

Internalization of TrkB-targeted PCL by RAW264 cells was enhanced and faster when compared with PCL having the corresponding scrambled peptide. Likewise, binding and augmented uptake were confirmed for TrkB⁺ SH-SY5Y cells, with targeted PCL appearing in the cytoplasm after 20 minutes of incubation.

CONCLUSION

We demonstrate here the feasibility of targeting liposomes to TrkB-expressing cells by 18-mer peptides, promoting cellular uptake (at least partly into endosomes) via receptor-mediated pathways.

Peptide-mediated targeting of liposomes to TrkB receptor-expressing cells

Background

The neurotrophic receptor tyrosine kinase B (TrkB) has diverse signaling roles in neurons and tumor cells. Accordingly, its suppressive targeting is of interest in neuroblastoma and other tumors, whereas its role in improving survival is focused in neurons. Here we describe targeting of TrkB-binding peptide-conjugated liposomes (PCL) to the TrkB-expressing mouse macrophage-like cell line RAW264, and to all-trans-retinoic acid-treated neuron-like TrkB⁺ SH-SY5Y human neuroblastoma cells.

Methods

Binding and internalization of PCL was monitored by flow cytometry and confocal fluorescence microscopy.

Results

Internalization of TrkB-targeted PCL by RAW264 cells was enhanced and faster when compared with PCL having the corresponding scrambled peptide. Likewise, binding and augmented uptake were confirmed for TrkB⁺ SH-SY5Y cells, with targeted PCL appearing in the cytoplasm after 20 minutes of incubation.

Conclusion

We demonstrate here the feasibility of targeting liposomes to TrkB-expressing cells by 18-mer peptides, promoting cellular uptake (at least partly into endosomes) via receptor-mediated pathways.

Targeted delivery of Tet1 peptide functionalized polymersomes to the rat cochlear nerve

Polymersomes are nanosized vesicles formed from amphiphilic block copolymers, and have been identified as potential drug delivery vehicles to the inner ear. The aim of this study was to provide targeting to specific cells within the inner ear by functionalizing the polymersome surface with Tet1 peptide sequence. Tet1 peptide specifically binds to the trisialoganglioside clostridial toxin receptor on neurons and was expected to target the polymersomes toward the cochlear nerve. The Tet1 functionalized PEG-b-PCL polymersomes were administered using routine drug delivery routes: transtympanic injection and cochleostomy. Delivery via cochleostomy of Tet1 functionalized polymersomes resulted in cochlear nerve targeting; in contrast this was not seen after transtympanic injection.

Targeted delivery of Tet1 peptide functionalized polymersomes to the rat cochlear nerve

Polymersomes are nanosized vesicles formed from amphiphilic block copolymers, and have been identified as potential drug delivery vehicles to the inner ear. The aim of this study was to provide targeting to specific cells within the inner ear by functionalizing the polymersome surface with Tet1 peptide sequence. Tet1 peptide specifically binds to the trisialoganglioside clostridial toxin receptor on neurons and was expected to target the polymersomes toward the cochlear nerve. The Tet1 functionalized PEG-b-PCL polymersomes were administered using routine drug delivery routes: transtympanic injection and cochleostomy. Delivery via cochleostomy of Tet1 functionalized polymersomes resulted in cochlear nerve targeting; in contrast this was not seen after transtympanic injection.

Characterization of presbyequilibrium among institutionalized elderly persons

OBJECTIVE

The aim was to characterize dizziness, vertigo, poor maintenance of posture, and sudden instabilities (called presbyequilibrium) among institutionalized elderly to model and identify possible treatable causes.

METHODS

A questionnaire based study focusing on symptoms among 72 elderly persons from a single residential facility and followed them for 3 years.

RESULTS

Dizziness, vertigo, poor maintenance of posture, and black-outs were reported by 68% of the 72 elderly and make them at risk for falls, and reduced quality of life. The most common complaint was postural instability, with a tendency to fall. "Spinning" vertigo and "floating" sensation had a strong inter-correlation and correlated with habitual falls. The various dizziness symptoms often occurred in combinations. Attacks of self-experienced syncope never occurred alone but always in combination with "spinning vertigo" or "tendency to fall". In factorial analysis, presbyequilibrium could be divided into six categories. Two of these categories correlated with falls.

CONCLUSIONS

Among elderly, presbyequilibrium is commonly characterized by a combination of phenomena involving perceptual, orientation, postural, and autonomic manifestations. It is often difficult to obtain an accurate history from the elderly and the presence of vestibular symptoms is frequently overlooked. Taking a careful history and utilizing the classification of symptoms that emerged from the factorial analysis may give a deeper understanding of the etiology of presbyequilibrium, thereby facilitating appropriate rehabilitation.

Oval Window Transport of Gd-DOTA from Rat Middle Ear to Vestibulum and Scala Vestibuli Visualized by in vivo Magnetic Resonance Imaging

Objectives:

We tested our hypothesis that the oval window (OW) potentially functions as a route to carry substances from the middle ear to the vestibulum and then the scala vestibuli through the annular ligament across the stapediovestibular joint.

Methods:

Gd-DOTA was either injected into the lateral attic compartment of rats with a high-performance polyimide tube in a selective OW delivery group, or administered to the middle ear cavity of two groups of rats in which the OW was either sealed or not sealed. The dynamic uptake of Gd-DOTA in the inner ear was visualized with a 4.7-T magnetic resonance imaging machine.

Results:

In the selective OW delivery group, Gd-DOTA appeared in the vestibulum and in the basal turn of the scala vestibuli but not in the scala tympani on T1-weighted images acquired at 10 minutes after Gd-DOTA administration (the earliest available time point of magnetic resonance imaging). In the sealed-OW group, immediate uptake of Gd-DOTA was absent in the vestibulum and scala vestibuli. Measurement of the signal ratio of the vestibulum to that of the scala tympani showed that selective OW delivery induced the greatest signal ratio and that sealing of the OW induced the lowest signal ratio.

Conclusions:

The OW is a genuine and efficient pathway to transport Gd-DOTA from the middle ear to the vestibulum.