Chemical composition of Galla chinensis extract and the effect of its main component(s) on the prevention of enamel demineralization in vitro

To determine the chemical composition of Galla chinensis extract(GCE) by several analysis techniques and to compare the efficacy of GCE and its main component(s) in inhibition of enamel demineralization,for the development of future anticaries agents,main organic composition of GCE was qualitatively determined by liquid chromatography-time of flight-mass spectrometry(LC-TOF-MS) and quantified by high-performance liquid chromatography-diode array detector(HPLC-DAD).Inorganic ions were tested by inductively coupled plasma-atomic emission spectroscopy and F was especially measured by ion chromatography.Then,bovine enamel blocks were randomly divided into four treatment groups and were subjected to a pH-cycling regime for 12 times.Each cycle included 5-min applications with one of four treatments:4 g?L 21 GCE solution,4 g?L 21 gallic acid(GA) solution,1 g?L 21 NaF solution(positive control),deionized water(DDW,negative control),and then 60-min application in pH 5.0 acidic buffer and 5-min application in neutral buffer.Acidic buffers were retained for calcium analysis.The main organic composition of GCE were GA and its isomer,and,to a lesser extent,small molecule gallotannins.The content of GA in GCE was 71.3%60.2%(w/w).Inorganic ions were present in various amounts,of which Ca was(13662.82) mg?g 21,and Zn was(6.860.1) mg?g 21.No F was detected in GCE.In pH cycling,GA showed an effect similar to GCE in inhibiting enamel demineralization(P.0.05).GA was found to be the main effective,demineralization inhibiting component of GCE and could be a promising agent for the development of anticaries agents.     

Influence of acrylamide monomer addition to the acrylic denture-base resins on mechanical and physical properties

The aim of the study was to evaluate the effect of adding acrylamide monomer （AAm） on the characterization, flexural strength, flexural modulus and thermal degradation temperature of poly（methyl methacrylate） （PMMA） denture-base resins. Specimens （n= 10） were fabricated from a conventional heat-activated QC-20 （Qc-） and a microwave heat-activated Acron MC （Ac-） PMMA resins. Powder/ liquid ratio followed the manufacturer＇s instructions for the control groups （Qc-c and Ac-c） and for the copolymer groups, the resins were prepared with 5% （-5）, 10% （- 10）, 15% （- 15） and 20% （-20） acrylamide contents, according to the molecular weight ratio, respectively. The flexural strength and flexural modulus were measured by a three-point bending test. The data obtained were statistically analyzed by Kruskal-Wallis test （a=O.05） to determine significant differences between the groups, The chemical structures of the resins were characterized by the nuclear magnetic resonance spectroscopy. Thermal stabilities were determined by thermogravimetric analysis （TGA） with a heating rate of 10 ~C.min-1 from 35 ~C to 600 ~C. Control groups from both acrylic resins showed the lowest flexural strength values. Qc-15 showed significant increase in the flexural strength when compared to Qc-c （P〈O.01）. Ac-10 and Ac-15 showed significance when compared to Ac-c （P〈O.01）. Acrylamide incorporation increased the elastic modulus in Qc-10, Qc-15 and Qc-20 when compared to Qc-c （P〈0.01）. Also significant increase was observed in Ac-10, Ac-15 and Ac-20 copolymer groups when compared to Ac-c （P〈0.01）. According to the 1H-nuclear magnetic resonance （NMR） results, acrylamide copolymerization was confirmed in the experimental groups. TGA results showed that the thermal stability of PMMA is increased by the insertion of AAm.     

Hyperpolarization-Activated Current (I h) in Vestibular Calyx Terminals: Characterization and Role in Shaping Postsynaptic Events

Calyx afferent terminals engulf the basolateral region of type I vestibular hair cells, and synaptic transmission across the vestibular type I hair cell/calyx is not well understood. Calyces express several ionic conductances, which may shape postsynaptic potentials. These include previously described tetrodotoxin-sensitive inward Na⁺ currents, voltage-dependent outward K⁺ currents and a K(Ca) current. Here, we characterize an inwardly rectifying conductance in gerbil semicircular canal calyx terminals (postnatal days 3–45), sensitive to voltage and to cyclic nucleotides. Using whole-cell patch clamp, we recorded from isolated calyx terminals still attached to their type I hair cells. A slowly activating, noninactivating current (I_h) was seen with hyperpolarizing voltage steps negative to the resting potential. External Cs⁺ (1–5 mM) and ZD7288 (100 μM) blocked the inward current by 97 and 83 %, respectively, confirming that I_h was carried by hyperpolarization-activated, cyclic nucleotide gated channels. Mean half-activation voltage of I_h was −123 mV, which shifted to −114 mV in the presence of cAMP. Activation of I_h was well described with a third order exponential fit to the current (mean time constant of activation, τ, was 190 ms at −139 mV). Activation speeded up significantly (τ = 136 and 127 ms, respectively) when intracellular cAMP and cGMP were present, suggesting that in vivo I_h could be subject to efferent modulation via cyclic nucleotide-dependent mechanisms. In current clamp, hyperpolarizing current steps produced a time-dependent depolarizing sag followed by either a rebound afterdepolarization or an action potential. Spontaneous excitatory postsynaptic potentials (EPSPs) became larger and wider when I_h was blocked with ZD7288. In a three-dimensional mathematical model of the calyx terminal based on Hodgkin–Huxley type ionic conductances, removal of I_h similarly increased the EPSP, whereas cAMP slightly decreased simulated EPSP size and width.     

Influence of fiber posts on the fracture resistance of endodontically treated premolars with different dental defects

This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading.Fifty extracted single-rooted mandibular premolars were randomized into five groups.Each group was prepared according to numbers of residual walls ranged from 0 to 4.Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts.In no-post groups,gutta percha point 2 mm below cemento-enamel junction was removed.Composite resin was adapted to the well and used to shape the core directly.Each tooth was restored with a complete metal crown.Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles.Then a quasi-statically load was applied in a universal testing machine 306 to the long axis with a crosshead speed of 1 mm？min21until fracture.Data were analyzed with one-way analysis of variance and pairwise comparison（P,0.05）.No specimens failed during dynamic loading.The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant（P,0.05）.Placement of fiber posts had a significant effect when fewer than two walls remained（P,0.05）,but it had no significant influence in groups with two,three or four walls（P.0.05）.Fiber post did not change failure mode,and the fracture pattern was mainly favorable.More dentin walls need to be retained in clinic.When no less than two walls remained,a fiber post is not always necessary.     

Efficacy of two calcium phosphate pastes on the remineralization of artificial caries： a randomized controlled double-blind in situ study

To test the efficacy of two calcium phosphate pastes compared to that of fluoride toothpaste on remineralizing artificial caries in situ, this study had a double-blind crossover in situ design, involving three experimental phases of 14 days each, with an 8-day washout period between phases. Nine healthy subjects participated in the study. The subjects wore removable palatal appliances mounted with six human enamel slabs with artificial caries lesions, and in each of the experimental phases, used one of the following methods two times/day： group A, brushing with 1.0 g of Colgate Regular Flavor, followed by applying 0.25 g of Tooth Mousse Plus; group B, brushing with 0.25 g of Clinpro Tooth Crbme; and group C, brushing with 1.0 g of Colgate Regular Flavor. After 14 days, the enamel slabs （54 slabs/ group） were embedded in resin, sectioned and examined with a polarized-light microscope, and the lesion areas were quantified using Image-Pro Plus. All experimental groups showed a significant reduction in lesion area compared to the initial lesion area （paired t-test, P〈O.O01）. The mean reduction in lesion area of Groups A, B and C were （0.029__.0.010）, （0.030_＋0.009） and （0.027_＋0.009） mm2, respectively. There were no statistical differences between groups （KruskaI-Wallis test, P〉0.05）. All three groups remineralized the enamel slab lesions, indicating model sensitivity to fluoride. Given the differences in usage amounts and treated regimens, Clinpro Tooth Crbme provided similar benefits to the fluoride toothpaste; however, no additional benefit of Tooth Mousse Plus was observed when used in conjunction with the fluoride toothpaste.     

Enhanced Vestibulo-ocular Reflex to Electrical Vestibular Stimulation in Meniere’s Disease

Meniere’s disease is characterized by sporadic episodes of vertigo, nystagmus, fluctuating sensorineural hearing loss, tinnitus and aural pressure. Since Meniere’s disease can affect different regions of the vestibular labyrinth, we investigated if electrical vestibular stimulation (EVS) which excites the entire vestibular labyrinth may be useful to reveal patchy endorgan pathology. We recorded three-dimensional electrically evoked vestibulo-ocular reflex (eVOR) to transient EVS using bilateral, bipolar 100-ms current steps at intensities of 0.9, 2.5, 5.0, 7.5 and 10.0 mA with dual-search coils in 12 unilateral Meniere’s patients. Their results were compared to 17 normal subjects. Normal eVOR had tonic and phasic spatiotemporal properties best described by the torsional component, which was four times larger than horizontal and vertical components. At EVS onset and offset of 8.9 ms latency, there were phasic eVOR initiation (M = 1,267 °/s²) and cessation (M = −1,675 °/s²) acceleration pulses, whereas during the constant portion of the EVS, there was a maintained tonic eVOR (M = 9.1 °/s) at 10 mA. However in Meniere’s disease, whilst latency of EVS onset and offset was normal at 9.0 ms, phasic eVOR initiation (M = 1,720 °/s²) and cessation (M = −2,523 °/s²) were enlarged at 10 mA. The initiation profile was a bimodal response, whilst the cessation profile frequently did not return to baseline. The tonic eVOR (M = 20.5 °/s) exhibited a ramped enhancement of about twice normal at 10 mA. Tonic eVOR enhancement was present for EVS >0.9 mA and disproportionately enhanced the torsional, vertical and horizontal components. These eVOR abnormalities may be a diagnostic indicator of Meniere’s disease and may explain the vertigo attacks in the presence of declining mechanically evoked vestibular responses.     

Sensory innervation around immediately vs. delayed loaded implants:a pilot study

Although neurophysiological and psychophysical proof of osseoperception is accumulating, histomorphometric evidence for the neural mechanisms of functional compensation following immediate and delayed ...     

Growth inhibitory response and ultrastructural modification of oral-associated candidal reference strains （ATCC） by Piper betle L. extract

Candida species have been associated with the emergence of strains resistant to selected antifungal agents. Plant products have been used traditionally as alternative medicine to ease mucosal fungal infections. This study aimed to investigate the effects of Piper betle extract on the growth profile and the ultrastructure of commonly isolated oral candidal cells. The major component of Po betle was identified using liquid chromatography-mass spectrophotometry （LC-MS/MS）. Seven ATCC control strains of Candida species were cultured in yeast peptone dextrose broth under four different growth environments： （i） in the absence of P. betle extract; and in the presence of P. beUeextract at respective concentrations of （ii） 1 mg.mL-1; （iii） 3 mg.mL-1; and （iv） 6 mg.mL- 1 The growth inhibitory responses of the candidal cells were determined based on changes in the specific growth rates （μ）. Scanning electron microscopy （SEM） was used to observe any ultrastructural alterations in the candida colonies. LC-MS/MS was performed to validate the presence of bioactive compounds in the extract. Following treatment, it was observed that the p-values of the treated cells were significantly different than those of the untreated cells （P〈0.05）, indicating the fungistatic properties of the P. beUe extract. The candidal population was also reduced from an average of 13.44× 10^6 to 1.78×10^6 viable cell counts （CFU）.mL-1, SEM examination exhibited physical damage and considerable morphological alterations of the treated cells. The compound profile from LC-MS/MS indicated the presence of hydroxybenzoic acid, chavibetol and hydroxychavicol in P. betle extract. The effects of P. betle on candida cells could potentiate its antifungal activity.     

Tumor Necrosis Factor-alpha-mutant Mice Exhibit High Frequency Hearing Loss

Exogenous tumor necrosis factor-alpha (TNF-α) plays a role in auditory hair cell death by altering the expression of apoptosis-related genes in response to noxious stimuli. Little is known, however, about the function of TNF-α in normal hair cell physiology. We, therefore, investigated the cochlear morphology and auditory function of TNF-α-deficient mice. Auditory evoked brainstem response showed significantly higher thresholds, especially at higher frequencies, in 1-month-old TNF-α^−/− mice as compared to TNF-α^+/− and wild type (WT); hearing loss did not progress further from 1 to 4 months of age. There was no difference in the gross morphology of the organ of Corti, lateral wall, and spiral ganglion cells in TNF-α^−/− mice compared to WT mice at 4 months of age, nor were there differences in the anatomy of the auditory ossicles. Outer hair cells were completely intact in surface preparations of the organ of Corti of TNF-α^−/− mice, and synaptic ribbon counts of TNF-α^−/− and WT mice at 4 months of age were similar. Reduced amplitudes of distortion product otoacoustic emissions, however, indicated dysfunction of outer hair cells in TNF-α^−/− mice. Scanning electron microscopy revealed that stereocilia were sporadically absent in the basal turn and distorted in the middle turn. In summary, our results demonstrate that TNF-α-mutant mice exhibit early hearing loss, especially at higher frequencies, and that loss or malformation of the stereocilia of outer hair cells appears to be a contributing factor.     

Current Steering with Partial Tripolar Stimulation Mode in Cochlear Implants

The large spread of excitation is a major cause of poor spectral resolution for cochlear implant (CI) users. Partial tripolar (pTP) mode has been proposed to reduce current spread by returning an equally distributed fraction (0.5 × σ) of current to two flanking electrodes and the rest to an extra-cochlear ground. This study tested the efficacy of incorporating current steering into pTP mode to add spectral channels. Different proportions of current [α × σ and (1 − α) × σ] were returned to the basal and apical flanking electrodes respectively to shape the electric field. Loudness and pitch perception with α from 0 to 1 in steps of 0.1 was simulated with a computational model of CI stimulation and tested on the apical, middle, and basal electrodes of six CI subjects. The highest σ allowing for full loudness growth within the implant compliance limit was chosen for each main electrode. Pitch ranking was measured between pairs of loudness-balanced steered pTP stimuli with an α interval of 0.1 at the most comfortable level. Results demonstrated that steered pTP stimuli with α around 0.5 required more current to achieve equal loudness than those with α around 0 or 1, maybe due to more focused excitation patterns. Subjects usually perceived decreasing pitches as α increased from 0 to 1, somewhat consistent with the apical shift of the center of gravity of excitation pattern in the model. Pitch discrimination was not better with α around 0.5 than with α around 0 or 1, except for some subjects and electrodes. For three subjects with better pitch discrimination, about half of the pitch ranges of two adjacent main electrodes overlapped with each other in steered pTP mode. These results suggest that current steering with focused pTP mode may improve spectral resolution and pitch perception with CIs.     

Isolation and characterisation of human gingival margin-derived STRO-1/MACS~+ and MACS~-cell populations

Recently,gingival margin-derived stem/progenitor cells isolated via STRO-1/magnetic activated cell sorting(MACS) showed remarkable periodontal regenerative potential in vivo.As a second-stage investigation,the present study’s aim was to perform in vitro characterisation and comparison of the stem/progenitor cell characteristics of sorted STRO-1-positive(MACS~+) and STRO-1-negative(MACS~-) cell populations from the human free gingival margin.Cells were isolated from the free gingiva using a minimally invasive technique and were magnetically sorted using anti-STRO-1 antibodies.Subsequently,the MACS~+ and MACS~- cell fractions were characterized by flow cytometry for expression of CD14,CD34,CD45,CD73,CD90,CD105,CD146/MUC18 and STRO-1.Colony-forming unit(CFU) and multilineage differentiation potential were assayed for both cell fractions.Mineralisation marker expression was examined using real-time polymerase chain reaction(PCR).MACS~+ and MACS- cell fractions showed plastic adherence.MACS~+ cells,in contrast to MACS- cells,showed all of the predefined mesenchymal stem/progenitor cell characteristics and a significantly higher number of CFUs(P<0.01).More than 95%of MACS~+ cells expressed CD105,CD90 and CD73;lacked the haematopoietic markers CD45,CD34 and CD14,and expressed STRO-1 and CD146/MUC18.MACS- cells showed a different surface marker expression profile,with almost no expression of CD14 or STRO-1,and more than 95%of these cells expressed CD73,CD90 and CD146/MUC18,as well as the haematopoietic markers CD34 and CD45 and CD105.MACS~+ cells could be differentiated along osteoblastic,adipocytic and chondroblastic lineages.In contrast,MACS- cells demonstrated slight osteogenic potential.Unstimulated MACS~+ cells showed significantly higher expression of collagen I(P<0.05) and collagen III(P<0.01),whereas MACS~- cells demonstrated higher expression of osteonectin(P<0.05;MannWhitney).The present study is the first to compare gingival MACS~+ and MACS- cell populations demonstrating that MACS~+ cells,in contrast to MACS- cells,harbour stem/progenitor cell characteristics.This study also validates the effectiveness of the STRO-l/MACS~+technique for the isolation of gingival stem/progenitor cells.Human free gingival margin-derived STRO-1/MACS~+ cells are a unique renewable source of multipotent stem/progenitor cells.     

Preliminary Findings from Our Experience in Anterior Palatoplasty for the Treatment of Obstructive Sleep Apnea

Objectives

Obstructive sleep apnea (OSA) is a common disorder affecting at least 2% to 4% of adult population characterized by the collapse of the pharyngeal airway. It is well established that retropalatal region is the most common site of obstruction. Consequently, many surgical techniques have been introduced. The purpose of this study is to present our preliminary results in the anterior palatoplasty (AP) compared with results of uvulopalatal flap (UPF).

Methods

Thirty-eight consecutive patients with mild-moderate OSA were prospectively enrolled into a randomised surgical protocol. Surgical success was measured primarily by satisfactory reduction in snoring, as reported by snoring assessment questionnaire (SQ) of sleep partners. Secondary outcomes measures included improvement in the Epworth Sleepiness Scale (ESS) scores, changes in the magnitude of pharyngeal collapse, and postoperative pain intensity.

Results

The ESS after AP improved from a preoperative value 8.5±3.7 to a postoperative mean of 4.9±3.2 (P<0.001) after UPF improved from a preoperative value of 8.1±3.5 to 5.2±3.2 postoperatively (P<0.001). The results of satisfactory reduction in the volume of snoring and response at polysomnographic data were also similar in both procedures. We reported a statistically significant difference of the collapse noted at Müller manoeuvre that improved from 2.7±1.0 on average, to 1.1±0.9 (P<0.001) after AP and with a lesser extent, (from 2.8±1.1 on average to 1.8±1.1; P<0.05), after UPF. The mean duration of pain was 10.8 days for UPF patients and 7.1 days for AP patients. The mean pain score in the first 3 days, was 6.8 in UPF patients and 5.1 in AP patients.

Conclusion

The subjective and objective improvements evidenced may suggest how AP is far superior to other techniques aimed at creating a palatal fibrotic scar. In the light of these results we can suggest AP procedure as more practical and comfortable when compared to UPF.     

Influence of cyclic loading on the fracture toughness and load bearing capacities of all-ceramic crowns

The purpose of this study was to investigate how cyclic loading influenced the fracture toughness of hot-press lithium disilicate and zirconia core materials and whether there was an increase in the propensity for crown failure. Two types of all-ceramic crowns including the IPS e.max Press system （n=24） and the Lava zirconia system （n=24）, were selected. Sectioned specimens were subjected to cyclic loading with the maximum magnitude of 200 N （R=0.1） until two million cycles. The material properties including Young＇s modulus （E） and hardness （H） and the fracture toughness （K,c） of the core materials were evaluated using indentation methods （n= 12 each）. The load-bearing capacities of the specimens were examined by means of monotonic load to fracture （n=12 each）. It was found that the material properties, including E, Hand Knc, of the two types of dental ceramics, were reduced. Statistical analysis indicated that there were no significant influences of fatigue loading on material properties E and H for both types of dental ceramics or Kgc for zirconia, while for the IPS e.max Press core, K,c, which was parallel to the direction of the lithium disilicate crystals, was significantly reduced （P-0.001）. A conclusion was drawn that zirconia possesses high mechanical reliability and sustainable capacity to resist fatigue loading, while fatigue loading remarkably degraded the anisotropic mechanical behaviour of hot-press lithium disilicate ceramics.     

Stapes Vibration in the Chinchilla Middle Ear: Relation to Behavioral and Auditory-Nerve Thresholds

The vibratory responses to tones of the stapes and incus were measured in the middle ears of deeply anesthetized chinchillas using a wide-band acoustic-stimulus system and a laser velocimeter coupled to a microscope. With the laser beam at an angle of about 40 ° relative to the axis of stapes piston-like motion, the sensitivity-vs.-frequency curves of vibrations at the head of the stapes and the incus lenticular process were very similar to each other but larger, in the range 15–30 kHz, than the vibrations of the incus just peripheral to the pedicle. With the laser beam aligned with the axis of piston-like stapes motion, vibrations of the incus just peripheral to its pedicle were very similar to the vibrations of the lenticular process or the stapes head measured at the 40 ° angle. Thus, the pedicle prevents transmission to the stapes of components of incus vibration not aligned with the axis of stapes piston-like motion. The mean magnitude curve of stapes velocities is fairly flat over a wide frequency range, with a mean value of about 0.19 mm^.(s Pa⁻¹), has a high-frequency cutoff of 25 kHz (measured at −3 dB re the mean value), and decreases with a slope of about −60 dB/octave at higher frequencies. According to our measurements, the chinchilla middle ear transmits acoustic signals into the cochlea at frequencies exceeding both the bandwidth of responses of auditory-nerve fibers and the upper cutoff of hearing. The phase lags of stapes velocity relative to ear-canal pressure increase approximately linearly, with slopes equivalent to pure delays of about 57–76 μs.     

A Genome-Wide Association Study of Chronic Otitis Media with Effusion and Recurrent Otitis Media Identifies a Novel Susceptibility Locus on Chromosome 2

Chronic otitis media with effusion (COME) and recurrent otitis media (ROM) have been shown to be heritable, but candidate gene and linkage studies to date have been equivocal. Our aim was to identify genetic susceptibility factors using a genome-wide association study (GWAS). We genotyped 602 subjects from 143 families with 373 COME/ROM subjects using the Illumina Human CNV370-Duo DNA Bead Chip (324,748 SNPs). We carried out the GWAS scan and imputed SNPs at the regions with the most significant associations. Replication genotyping in an independent family-based sample was conducted for 53 SNPs: the 41 most significant SNPs with P < 10⁻⁴ and 12 imputed SNPs with P < 10⁻⁴ on chromosome 15 (near the strongest signal). We replicated the association of rs10497394 (GWAS discovery P = 1.30 × 10⁻⁵) on chromosome 2 in the independent otitis media population (P = 4.7 × 10⁻⁵; meta-analysis P = 1.52 × 10⁻⁸). Three additional SNPs had replication P values < 0.10. Two were on chromosome 15q26.1 including rs1110060, the strongest association with COME/ROM in the primary GWAS (P = 3.4 ×10⁻⁷) in KIF7 intron 7 (P = 0.072), and rs10775247, a non-synonymous SNP in TICRR exon 2 (P = 0.075). The third SNP rs386057 was on chromosome 5 in TPPP intron 1 (P = 0.045). We have performed the first GWAS of COME/ROM and have identified a SNP rs10497394 on chromosome 2 is significantly associated with COME/ROM susceptibility. This SNP is within a 537 kb intergenic region, bordered by CDCA7 and SP3. The genomic and functional significance of this newly identified locus in COME/ROM pathogenesis requires additional investigation.     

Gentamicin is Primarily Localized in Vestibular Type I Hair Cells after Intratympanic Administration

Intratympanic (IT) gentamicin injections are effective in the control of episodic vertigo due to Ménière’s disease. Histological studies in animals have found that the loss of type I vestibular hair cells far exceeds that of type II cells after IT gentamicin treatment. The objective of this study was to determine whether this selective toxicity for type I hair cells might be due to selective concentration of the drug by these cells. Gentamicin was localized within the vestibular epithelium by both direct and indirect methods. Gentamicin conjugated to Texas Red® was used as a direct tracer, and anti-gentamicin antibody provided an indirect means of localization. Conjugated or unconjugated gentamicin was injected into the left tympanic space of chinchillas. The animals were killed and fixed 1 or 3 weeks post-treatment. Confocal fluorescence microscopy was used to determine the localization of gentamicin in semicircular canal cristae. Results from the animals killed within 1 week of administration showed that numerous type I hair cells still remained throughout the epithelium. The mean intensity in grayscale units (0–255) of anti-gentamicin labeling for type I hair cells was 28.14 (95% CI 24.60–31.69), for type II hair cells was 17.09 (14.99–19.20), and for support cells was 5.35 (5.34–5.46; p < 0.001, ANOVA). Anti-gentamicin antibody labeling appeared in the majority of type I hair cells throughout their cytoplasm, but with greater intensity at the apex (p < 0.001). Intensity of fluorescence with Texas-Red conjugated gentamicin was 25.38 (22.83–27.94) in type I hair cells, 15.60 (14.73–16.48) in type II cells, and 12.62 (12.06–13.17) in support cells (p < 0.001, ANOVA). These results suggest that type I hair cells are more susceptible to gentamicin because they more avidly take up or retain the drug in the early period after administration.     

Hearing Loss is an Early Consequence of Npc1 Gene Deletion in the Mouse Model of Niemann–Pick Disease,Type C

Niemann–Pick disease, type C1 (NPC1) is a rare lysosomal lipidosis that is most often the result of biallelic mutations in NPC1, and is characterized by a fatal neurological degeneration. The pathophysiology is complex, and the natural history of the disease is poorly understood. Recent findings from patients with NPC1 and hearing loss suggest that multiple steps along the auditory pathway are affected. The current study was undertaken to determine the auditory phenotype in the Npc1^nih mutant mouse model, to extend analyses to histologic evaluation of the inner ear, and to compare our findings to those reported from human patients. Auditory testing revealed a progressive high-frequency hearing loss in Npc1^−/− mice that is present as early as postnatal day 20 (P20), well before the onset of overt neurological symptoms, with evidence of abnormalities involving the cochlea, auditory nerve, and brainstem auditory centers. Distortion product otoacoustic emission amplitude and auditory brainstem response latency data provided evidence for a disruption in maturational development of the auditory system in Npc1^−/− mice. Anatomical study demonstrated accumulation of lysosomes in neurons, hair cells, and supporting cells of the inner ear in P30 Npc1^−/− mice, as well as increased numbers of inclusion bodies, myelin figures, and swollen nerve endings in older (P50–P70) mutant animals. These findings add unique perspective to the pathophysiology of NPC disease and suggest that hearing loss is an early and sensitive marker of disease progression.     

Evaluation of zirconia–porcelain interface using X-ray diffraction

The aim of this study was to determine if accelerated aging of porcelain veneering had an effect on the surface properties specific to a tetragonal-to-monoclinic transformation (TMT) of zirconia restorations. Thirty-six zirconia samples were milled and sintered to simulate core fabrication followed by exposure to various combinations of surface treatments including as-received (control), hydrofluoric acid (HF), application of liner plus firings, application of porcelain by manual layering and pressing with firing, plus accelerated aging. The quantity of transformed tetragonal to monoclinic phases was analyzed utilized an X-ray diffractometer and one-way analysis of variance was used to analyze data. The control samples as provided from the dental laboratory after milling and sintering process had no TMT (X_m = 0). There was an effect on zirconia samples of HF application with TMT (X_m = 0.8%) and liner plus HF application with TMT (X_m = 8.7%). There was an effect of aging on zirconia samples (no veneering) with significant TMT (X_m = 70.25%). Both manual and pressing techniques of porcelain applications reduced the TMT (manual, X_m = 4.41%, pressing, X_m = 11.57%), although there was no statistical difference between them. It can be concluded that simulated applications of porcelain demonstrated the ability to protect zirconia from TMT after aging with no effect of a liner between different porcelain applications. The HF treatment also caused TMT.     

Decreased Immunoreactivities and Functions of the Chloride Transporters, KCC2 and NKCC1, in the Lateral Superior Olive Neurons of Circling Mice

Objectives

We tested the possibility of differential expression and function of the potassium-chloride (KCC2) and sodium-potassium-2 chloride (NKCC1) co-transporters in the lateral superior olive (LSO) of heterozygous (+/cir) or homozygous (cir/cir) mice.

Methods

Mice pups aged from postnatal (P) day 9 to 16 were used. Tails from mice were cut for DNA typing. For Immunohistochemical analysis, rabbit polyclonal anti-KCC2 or rabbit polyclonal anti-NKCC1 was used and the density of immunolabelings was evaluated using the NIH image program. For functional analysis, whole cell voltage clamp technique was used in brain stem slices and the changes of reversal potentials were evaluated at various membrane potentials.

Results

Immunohistochemical analysis revealed both KCC2 and NKCC1 immunoreactivities were more prominent in heterozygous (+/cir) than homozygous (cir/cir) mice on P day 16. In P9-P12 heterozygous (+/cir) mice, the reversal potential (E_gly) of glycine-induced currents was shifted to a more negative potential by 50 µM bumetanide, a known NKCC1 blocker, and the negatively shifted E_gly was restored by additional application of 1 mM furosemide, a KCC2 blocker (-58.9±2.6 mV to -66.0±1.5 mV [bumetanide], -66.0±1.5 mV to -59.8±2.8 mV [furosemide+bumetanide], n=11). However, only bumetanide was weakly, but significantly effective (-60.1±2.9 mV to -62.7±2.6 mV [bumetanide], -62.7±2.6 mV to -62.1±2.5 mV [furosemide+bumetanide], n=7) in P9-P12 homozygous (cir/cir) mice.

Conclusion

The less prominent immunoreactivities and weak or absent responses to bumetanide or furosemide suggest impaired function or delayed development of both transporters in homozygous (cir/cir) mice.