MuRF-1 is Involved in Laryngeal Muscle Denervation Atrophy by Regulating G-Actin Ubiquitination.

OBJECTIVE: Muscle RING-finger protein-1 (MuRF-1), an E3 ubiquitin ligase, has been reported to aggravate skeletal muscle denervated atrophy by mediating the ubiquitination degradation of multiple proteins, whereas the molecular mechanism underlying MuRF-1-mediated internal laryngeal muscle denervated atrophy remains unknown. METHODS: A rat unilateral recurrent laryngeal nerve (RLN) transection model was established to evaluate denervated muscle atrophy of the larynx. The expression of MuRF-1, G- and F-actin in thyroarytenoid muscle (TA) myocytes before and after RLN injury was analyzed by immunofluorescence and Western blotting. Coimmunoprecipitation experiments detected molecular interactions between MuRF-1 and G-actin. Immunoprecipitation tested MuRF-1-mediated ubiquitination of G-actin in denervated and innervated TA muscle tissues. The shRNA-MuRF-1 AAV was used to suppress MuRF-1 expression in denervated TA muscles in vivo. RESULTS: First, MuRF-1 expression was significantly elevated in denervated TA muscle compared to innervated TA muscle (p < 0.001). Second, there was a progressive increase in the G/F-actin ratio in TA myocytes from day 3 to 14 after RLNI (p < 0.01). Furthermore, colocalization of MuRF-1 and G-actin in denervated TA myocytes was observed. Moreover, the upregulation of MuRF-1 was closely associated with the ubiquitination of G-actin in denervated TA myocytes and muscle tissues. Knockdown of MuRF-1 decelerated the degree of TA muscle atrophy compared with that in the Blank and NC groups (p < 0.001) but seemed to promote the compensatory movement of the healthy side. CONCLUSION: Collectively, we illustrate a novel molecular mechanism underlying MuRF-1-mediated internal laryngeal muscle denervated atrophy in that MuRF-1 could promote disequilibrium of the G/F-actin ratio by regulating G-actin ubiquitination. LEVEL OF EVIDENCE: NA Laryngoscope, 134:855-864, 2024.

Prevalence of Laryngeal Muscle Tension in Patients With Obstructive Sleep Apnea.

OBJECTIVE/HYPOTHESIS: To determine the prevalence of laryngeal muscle tension in patients with obstructive sleep apnea (OSA). STUDY DESIGN: Retrospective case-control. METHODS: A total of 75 patients were included in this study. These were divided into a study group with a history of OSA (n = 45), and a control group with no history of OSA matched according to age and gender (n = 30). The risk of OSA was assessed using the STOP-BANG questionnaire. Demographic data included age, gender, body mass index, smoking, history of snoring, history of use of continuous positive airway pressure, and history of reflux disease. Symptoms such as hoarseness, throat clearing/cough, and globus sensation were also noted. The video recordings of the flexible nasopharyngoscopy of both groups were analyzed for the presence or absence of four laryngeal muscle tension patterns (MTPs). RESULTS: Twenty-five patients of the study group (55.6%) had signs of laryngeal muscle tension on laryngeal endoscopy compared to nine in the control patients (30%) (P = 0.029). The most common MTP observed in the study group was MTP III (n = 19), followed by MTP II (n = 17). Laryngeal muscle tension was more prevalent in patients of the intermediate and high-risk categories compared to those of the low-risk category (73.3% and 62.5% vs 28.6%, respectively) (P = 0.042). Patients with at least one MTP had more dysphonia and throat clearing than patients without any MTP. CONCLUSION: Patients with a history of OSA have a higher prevalence of laryngeal muscle tension in comparison to subjects with no history of OSA. Moreover, patients at high risk of OSA have a higher prevalence of laryngeal muscle tension than those at low risk of OSA.

Extrinsic Laryngeal Muscle Tension in Primary Muscle Tension Dysphonia with Shear Wave Elastography.

OBJECTIVES: It has been assumed that patients with primary muscle tension dysphonia (pMTD) have more extrinsic laryngeal muscle (ELM) tension, but tools to study this phenomenon lack. Shear wave elastography (SWE) is a potential method to address these shortcomings. The objectives of this study were to apply SWE to the ELMs, compare SWE measures to standard clinical metrics, and determine group differences in pMTD and typical voice users before and after vocal load. METHODS: SWE measurements of the ELMs from ultrasound examinations of the anterior neck, supraglottic compression severities from laryngoscopic images, cepstral peak prominences (CPP) from voice recordings, and self-perceptual ratings of vocal effort and discomfort were obtained in voice users with (N = 30) and without (N = 35) pMTD, before and after a vocal load challenge. RESULTS: ELM tension significantly increased from rest-to-voiced conditions in both groups. However, the groups were similar in their ELM stiffness levels at SWE at baseline, during vocalization, and post-vocal load. Levels of vocal effort and discomfort and supraglottic compression were significantly higher and CPP was significantly lower in the pMTD group. Vocal load had a significant effect on vocal effort and discomfort but not on laryngeal or acoustic patterns. CONCLUSION: SWE can be used to quantify ELM tension with voicing. Although the pMTD group reported significantly higher levels of vocal effort and vocal tract discomfort and, on average, exhibited significantly more severe supraglottic compression and lower CPP values, there were no group differences in levels of ELM tension using SWE. LEVEL OF EVIDENCE: 2 Laryngoscope, 133:3482-3491, 2023.

Measuring and modeling the effects of vagus nerve stimulation on heart rate and laryngeal muscles.

BACKGROUND: Reduced heart rate (HR) during vagus nerve stimulation (VNS) is associated with therapy for heart failure, but stimulation frequency and amplitude are limited by patient tolerance. An understanding of physiological responses to parameter adjustments would allow differential control of therapeutic and side effects. To investigate selective modulation of the physiological responses to VNS, we quantified the effects and interactions of parameter selection on two physiological outcomes: one related to therapy (reduced HR) and one related to side effects (laryngeal muscle EMG). METHODS: We applied a broad range of stimulation parameters (mean pulse rates (MPR), intra-burst frequencies, and amplitudes) to the vagus nerve of anesthetized mice. We leveraged the in vivo recordings to parameterize and validate computational models of HR and laryngeal muscle activity across amplitudes and temporal patterns of VNS. We constructed a finite element model of excitation of fibers within the mouse cervical vagus nerve. RESULTS: HR decreased with increased amplitude, increased MPR, and decreased intra-burst frequency. EMG increased with increased MPR. Preferential HR effects over laryngeal EMG effects required combined adjustments of amplitude and MPR. The model of HR responses highlighted contributions of ganglionic filtering to VNS-evoked changes in HR at high stimulation frequencies. Overlap in activation thresholds between small and large modeled fibers was consistent with the overlap in dynamic ranges of related physiological measures (HR and EMG). CONCLUSION: The present study provides insights into physiological responses to VNS required for informed parameter adjustment to modulate selectively therapeutic effects and side effects.

Exploring the mechanics of fundamental frequency variation during phonation onset.

Fundamental frequency patterns during phonation onset have received renewed interest due to their promising application in objective classification of normal and pathological voices. However, the associated underlying mechanisms producing the wide array of patterns observed in different phonetic contexts are not yet fully understood. Herein, we employ theoretical and numerical analyses in an effort to elucidate the potential mechanisms driving opposing frequency patterns for initial/isolated vowels versus vowels preceded by voiceless consonants. Utilizing deterministic lumped-mass oscillator models of the vocal folds, we systematically explore the roles of collision and muscle activation in the dynamics of phonation onset. We find that an increasing trend in fundamental frequency, as observed for initial/isolated vowels, arises naturally through a progressive increase in system stiffness as collision intensifies as onset progresses, without the need for time-varying vocal fold tension or changes in aerodynamic loading. In contrast, reduction in cricothyroid muscle activation during onset is required to generate the decrease in fundamental frequency observed for vowels preceded by voiceless consonants. For such phonetic contexts, our analysis shows that the magnitude of reduction in the cricothyroid muscle activation and the activation level of the thyroarytenoid muscle are potential factors underlying observed differences in (relative) fundamental frequency between speakers with healthy and hyperfunctional voices. This work highlights the roles of sometimes competing laryngeal factors in producing the complex array of observed fundamental frequency patterns during phonation onset.

Cortical basis for skilled vocalization.

Marmosets display remarkable vocal motor abilities. Macaques do not. What is it about the marmoset brain that enables its skill in the vocal domain? We examined the cortical control of a laryngeal muscle that is essential for vocalization in both species. We found that, in both monkeys, multiple premotor areas in the frontal lobe along with the primary motor cortex (M1) are major sources of disynaptic drive to laryngeal motoneurons. Two of the premotor areas, ventral area 6 (area 6V) and the supplementary motor area (SMA), are a substantially larger source of descending output in marmosets. We propose that the enhanced vocal motor skills of marmosets are due, in part, to the expansion of descending output from these premotor areas.

Laryngeal Muscle-Evoked Potential Recording as an Indicator of Vagal Nerve Fiber Activation.

BACKGROUND: Vagus nerve stimulation (VNS) is an adjunctive therapy for drug-resistant epilepsy. Noninvasive evoked potential recordings in laryngeal muscles (LMEPs) innervated by vagal branches may provide a marker to assess effective vagal nerve fiber activation. We investigated VNS-induced LMEPs in patients with epilepsy in acute and chronic settings. MATERIALS AND METHODS: A total of 17 of 25 patients underwent LMEP recordings at initiation of therapy (acute group); 15 of 25 patients after one year of VNS (chronic group); and 7 of 25 patients were tested at both time points (acute + chronic group). VNS-induced LMEPs were recorded following different pulse widths and output currents using six surface laryngeal EMG electrodes to calculate input/output curves and estimate LMEP latency, threshold current for minimal (Ithreshold), half-maximal (I50), and 95% of maximal (I95) response induction and amplitude of maximal response (Vmax). These were compared with the acute + chronic group and between responders and nonresponders in the acute and chronic group. RESULTS: VNS-induced LMEPs were present in all patients. Ithreshold and I95 values ranged from 0.25 to 1.00 mA and from 0.42 to 1.77 mA, respectively. Estimated mean LMEP latencies were 10 ± 0.1 milliseconds. No significant differences between responders and nonresponders were observed. In the acute + chronic group, Ithreshold values remained stable over time. However, at the individual level in this group, Vmax was lower in all patients after one year compared with baseline. CONCLUSIONS: Noninvasive VNS-induced LMEP recording is feasible both at initiation of VNS therapy and after one year. Low output currents (0.25-1.00 mA) may be sufficient to activate vagal Aα-motor fibers. Maximal LMEP amplitudes seemed to decrease after chronic VNS therapy in patients.

Effects of Vocal Training on Thyroarytenoid Muscle Neuromuscular Junctions and Myofibers in Young and Older Rats.

The purpose of this investigation was to determine the effects of vocal training on neuromuscular junction (NMJ) morphology and muscle fiber size and composition in the thyroarytenoid muscle, the primary muscle in the vocal fold, in younger (9-month) and older (24-month) Fischer 344 × Brown Norway male rats. Over 4 or 8 weeks of vocal training, rats of both ages progressively increased their daily number of ultrasonic vocalizations (USVs) through operant conditioning and were then compared to an untrained control group. Neuromuscular junction morphology and myofiber size and composition were measured from the thyroarytenoid muscle. Acoustic analysis of USVs before and after training quantified the functional effect of training. Both 4- and 8-week training resulted in less NMJ motor endplate dispersion in the lateral portion of the thyroarytenoid muscle in rats of both ages. Vocal training and age had no significant effects on laryngeal myofiber size or type. Vocal training resulted in a greater number of USVs with longer duration and increased intensity. This study demonstrated that vocal training induces laryngeal NMJ morphology and acoustic changes. The lack of significant effects of vocal training on muscle fiber type and size suggests vocal training significantly improves neuromuscular efficiency but does not significantly influence muscle strength changes.

Characteristics of Early Internal Laryngeal Muscle Atrophy After Recurrent Laryngeal Nerve Injuries in Rats.

OBJECTIVES/HYPOTHESIS: The present study investigated the characteristics of early internal laryngeal muscle atrophy in recurrent laryngeal nerve injury (RLNI) rats. STUDY DESIGN: To observe the characteristics of early internal laryngeal muscle atrophy post RLNI. METHODS: Rats were divided into three groups: sham-operated control group (n = 20), recurrent laryngeal nerve transverse injury group (RLNTI, n = 50), and recurrent laryngeal nerve blunt contusion group (RLNBC, n = 50). Five weeks after RLNI, certain rats were sacrificed weekly, and their laryngeal tissues were harvested. The atrophic features of internal laryngeal muscles were detected using hematoxylin and eosin. NF-κB and MuRF-1 levels were tested using IHC. RESULTS: The atrophic degree and fibrosis of thyroarytenoid, posterior cricoarytenoid, and lateral cricoarytenoid muscles were related to the type of RLNI. The average myofiber cross-sectional areas increased before an obvious decrease in the RLNTI and RLNBC groups. Muscle recovery occurred in the RLNBC group starting 4 weeks after RLNI, but only a weak trend was observed in the RLNTI group in the 5th week. During the muscle atrophy process, MuRF-1 and NF-κB were upregulated early and were maintained at a high level, which showed a trend similar to muscle atrophy. However, NF-κB expression was opposite to MuRF-1 expression and muscle atrophy when the muscles recovered. CONCLUSION: The atrophy degree of internal laryngeal muscles was associated with the type of RLNI. The NF-κB/MuRF-1 signaling pathway was involved in internal laryngeal muscle atrophy after RLNI, which is different from skeletal muscle after denervation. LEVEL OF EVIDENCE: NA Laryngoscope, 131:E1256-E1264, 2021.

Changes in Vocal Fold Morphology During Singing Over Two Octaves.

OBJECTIVE: Vocal folds are widely assumed to only elongate to raise vocal pitch. However, the mechanisms seem to be more complex and involve both elongation and tensioning of the vocal folds in series. The aim of the present study was to show that changes in vocal fold morphology depend on vocal fold elongation and tensioning during singing. STUDY DESIGN: This was a prospective study. METHODS: Forty-nine professional female singers (25 sopranos, 24 altos) were recruited and three-dimensional laryngeal images analyzed in a coronal view derived from high-resolution computed tomography scans obtained at the mean speaking fundamental frequency (ƒ0) and one (2ƒ0) and two octaves (4ƒ0) above ƒ0. RESULTS: The vocal fold angle, defined by a tangent above and below the vocal folds, was 58° at ƒ0, 47° at 2ƒ0, and 59° at 4ƒ0. CONCLUSION: The decreased caudomedial angle of the vocal fold from ƒ0 to 2ƒ0 (change in muscle belly from ";fat" to "thin") and increased angle from 2ƒ0 to 4ƒ0 (from "thin" to "fat") strongly supports the hypothesis that the vocal folds elongate and then tension when singing from ƒ0 to 4ƒ0. This is the first study to show this relationship in vivo.

Mapping Thyroarytenoid and Cricothyroid Activations to Postural and Acoustic Features in a Fiber-Gel Model of the Vocal Folds.

Any specific vowel sound that humans produce can be represented in terms of four perceptual features in addition to the vowel category. They are pitch, loudness, brightness, and roughness. Corresponding acoustic features chosen here are fundamental frequency (fo ), sound pressure level (SPL), normalized spectral centroid (NSC), and approximate entropy (ApEn). In this study, thyroarytenoid (TA) and cricothyroid (CT) activations were varied computationally to study their relationship with these four specific acoustic features. Additionally, postural and material property variables such as vocal fold length (L) and fiber stress (σ) in the three vocal fold tissue layers were also calculated. A fiber-gel finite element model developed at National Center for Voice and Speech was used for this purpose. Muscle activation plots were generated to obtain the dependency of postural and acoustic features on TA and CT muscle activations. These relationships were compared against data obtained from previous in vivo human larynx studies and from canine laryngeal studies. General trends are that fo and SPL increase with CT activation, while NSC decreases when CT activation is raised above 20%. With TA activation, acoustic features have no uniform trends, except SPL increases uniformly with TA if there is a co-variation with CT activation. Trends for postural variables and material properties are also discussed in terms of activation levels.

Hirano's cover-body model and its unique laryngeal postures revisited.

OBJECTIVES/HYPOTHESIS: In 1974, Minoru Hirano proposed his theory of voice production that is now known as the cover-body theory. He described the thyroarytenoid (TA) and cricothyroid (CT) muscles as the major determinants of vocal fold shape and stiffness, and theorized four typical laryngeal configurations resulting from unique TA/CT activations, with implications for the resulting voice quality. In this study, we directly observed the vocal fold medial surface shape under Hirano's unique TA/CT activation conditions to obtain a three-dimensional (3D) understanding of these laryngeal configurations during muscle activation. STUDY DESIGN: In vivo canine hemilarynx model. METHODS: Flesh points were marked along the medial surface of the vocal fold. Selective TA and CT activation were performed via respective laryngeal nerves. 3D reconstructions of the vocal fold medial surface were derived using digital image correlation. RESULTS: Low level TA and CT activation yielded anteroposterior lengthening and vertical thinning of the vocal fold. When TA activation is far greater than CT, the vocal fold shortens and thickens. With slightly greater TA than CT, activation the vocal length is maintained on average, whereas its vertical thickness decreases. With CT far greater than TA activation, the vocal fold lengthens and thins. In all conditions, glottal contour changes remained minimal. CONCLUSIONS: Analysis of the 3D geometry of the vocal fold medial surface under Hirano's four typical laryngeal configurations revealed that the key geometric changes during TA/CT interactions lie within the anteroposterior length and the vertical thickness of the vocal fold. LEVEL OF EVIDENCE: NA. Laryngoscope, 128:1412-1418, 2018.

Laryngeal manual therapy palpatory evaluation scale: A preliminary study to examine its usefulness in diagnosis of occupational dysphonia.

BACKGROUND: The aim of this study has been to assess the larynx and soft tissue around the vocal tract in a group of people with healthy voice, and in a group of patients with occupational dysphonia using the new laryngeal manual therapy palpatory evaluation scale (LMTPE). MATERIAL AND METHODS: The examinations were performed in a study (dysphonic) group of professional voice users who had developed voice disorders (N = 51) and in the control group of normophonic subjects (N = 50). All the participants underwent perceptual voice assessment and examination by means of the LMTPE scale. Additionally, phoniatric examination including VHI (Voice Handicap Index) questionnaire, GRBAS (the Grade of hoarseness, Roughness, Breathiness, Asthenic, Strained) perceptual evaluation, maximum phonation time (MPT) measurement and videostroboscopy was performed in the study group. RESULTS: The comparison of the LMTPE total score showed that the results of the study group were significantly poorer than those of controls (p < 0.001). In the study group, correlations were found between the LMTPE results and the VHI scores (p < 0.05), perceptual evaluation by the GRBAS (p < 0.05) and the objective parameter MPT (p < 0.05). CONCLUSIONS: The study has proven that the LMTPE scale is characterized by the high score of Cronbach's α ratio estimating the reliability of the test. The results have confirmed that the LMTPE scale seems to be a valuable tool, useful in diagnostics of occupational dysphonia, particularly of hyperfunction origin. Med Pr 2017;68(2):179-188.

Three-dimensional posture changes of the vocal fold from paired intrinsic laryngeal muscles.

OBJECTIVES/HYPOTHESIS: Although the geometry of the vocal fold medial surface affects voice quality and is critical in the treatment of glottic insufficiency, the prephonatory shape of the vocal fold medial surface is not well understood. In this study, we activated intrinsic laryngeal muscles individually and in combinations, and recorded the temporal sequence and precise three-dimensional configurational changes of the vocal fold medial surface. STUDY DESIGN: In vivo canine hemilarynx model. METHODS: A hemilaryngectomy was performed in an in vivo canine model and ink was used to mark the medial surface of the in situ vocal fold in a grid-like fashion. The thyroarytenoid (TA), lateral cricoarytenoid (LCA), cricothyroid (CT), and posterior cricoarytenoid (PCA) muscles were stimulated individually and in combinations. A right-angle prism whose hypotenuse formed the glottal midline provided two distinct views of the medial surface for a high-speed digital camera. Image-processing package DaVis (LaVision Inc., Goettingen, Germany) allowed time series cross-correlation analysis for three-dimensional deformation calculations of the vocal fold medial surface. RESULTS: Combined TA and LCA activation yields an evenly adducted rectangular glottal surface. Addition of thyroarytenoid to cricoarytenoid adducts the vocal fold from inferior to superior in a graded fashion allowing formation of a divergent glottis. Posterior cricoarytenoid has a bimodal relationship with thyroarytenoid favoring abduction. Cricothyroid and lateral cricoarytenoid yield unique glottal postures necessary but likely not conducive for efficient phonation. CONCLUSIONS: Understanding the three-dimensional geometry of the vocal fold medial surface will help us better understand the cause-effect relationship between laryngeal physiology and phonation. LEVEL OF EVIDENCE: NA Laryngoscope, 127:656-664, 2017.

Effect of Levodopa + Carbidopa on the Laryngeal Electromyographic Pattern in Parkinson Disease.

BACKGROUND: Vocal impairment is one of the main debilitating symptoms of Parkinson disease (PD). The effect of levodopa on vocal function remains unclear. OBJECTIVE: This study aimed to determine the effect of levodopa on electromyographic patterns of the laryngeal muscle in patients with PD. STUDY DESIGN: This is a prospective interventional trial. METHODS: Nineteen patients with PD-diagnosed by laryngeal electromyography-were enrolled. Cricothyroid and thyroarytenoid (TA) muscle activities were measured at rest and during muscle contraction (phonation), when participants were on and off medication (12 hours after the last levodopa dose). RESULTS: Prevalence of resting hypertonia in the cricothyroid muscle was similar in the off and on states (7 of 19, P = 1.00). Eight patients off medication and four patients on medication had hypertonic TA muscle at rest (P = 0.289). No electromyographic alterations were observed during phonation for either medication states. CONCLUSION: Despite a tendency for increased rest tracings in the TA muscle when participants were on medication, no association was found between laryngeal electromyography findings and levodopa + carbidopa administration.

An implantable system for In Vivo chronic electromyographic study in the larynx.

INTRODUCTION: Electromyography (EMG) plays an important role in exploring the mechanisms of selective reinnervation. An implantable system can help provide chronological information regarding reinnervation of laryngeal muscles. This study was designed to develop an implantable system for repeated recordings of spontaneous and evoked EMG from laryngeal muscles. METHODS: This implantable system has 4 bipolar stimulus cuffs for bilateral recurrent laryngeal nerves (RLNs) and superior laryngeal nerves (SLNs), and 4 EMG recording electrodes for bilateral vocal fold adductors (thyroarytenoid-lateral cricoarytenoid, TA-LCA) and abductor (posterior cricoarytenoid, PCA) muscles. The system was implanted in 8 canines for up to 41 weeks. RESULTS: The system showed good compatibility. Consistent EMG signals were recorded from both PCA and TA-LCA muscles. CONCLUSION: We developed a long-term implantable EMG system that is simple and capable of obtaining stable EMG recordings from canine laryngeal muscles with minimal risk of device breakage, trauma, or infection. Muscle Nerve 55: 706-714, 2017.

Increased Expression of MuRF1 Is Associated with Radiation-induced Laryngeal Muscle Atrophy.

BACKGROUND: Laryngeal muscles play an important role in breathing, sound production and trachea protection against food. Laryngeal dysfunctions during radiotherapy for head and neck cancers are common. In the present study, we aimed to investigate the early effect of radiation on the laryngeal muscles in vivo and possible mechanisms involved in this process. MATERIALS AND METHODS: Eight-week-old female C57bl/ mice received neck irradiation with a single dose of 25 Gy and bilateral thyroarytenoid (TA) muscles of mice were collected at day 3, 7 and 10 post-irradiation for evaluating muscle size, myosins, myosin heavy chain (MyHC) composition and MuRF1 protein levels. RESULTS: A significant reduction in the size of muscle fibers and myosins in the TA muscles were observed at days 3, 7, 10 after radiation (p<0.05). The loss of IIB myosin was more severe than that of IIA/X myosins at day 7 post-irradiation (75% vs. 64%). MuRF1 protein level was markedly increased at day 7 and 10 after radiation (p<0.05). CONCLUSION: Radiation induced an acute muscle fiber atrophy and myosin loss in the intrinsic laryngeal muscles. MuRF1 may play an important role in the radiation-induced protein degradation in the laryngeal muscles and warrants further investigation.

Preventive effects of bortezomib on denervation-induced atrophy of the intrinsic laryngeal muscles: an experimental study in the rat.

CONCLUSION: Bortezomib was effective in attenuating atrophy of the posterior cricoarytenoid (PCA) muscle, but not the thyroarytenoid (TA) muscle. This was probably due to differences in the fiber composition of the two muscles. The PCA muscle is composed of a combination of fast- and slow-twitch fibers, and therefore is more resistant to atrophy than the TA muscle, which is composed solely of fast-twitch fibers. OBJECTIVES: To investigate the preventive effects of bortezomib on denervation-induced atrophy of the TA and PCA muscles in the rat. METHODS: Following transection of the left recurrent laryngeal nerve, bortezomib (100 µg/kg) was administered subcutaneously on post-denervation days 1 and 4, followed by a 10-day rest period every 14 days; each 2-week period constituted a single treatment cycle. In controls, saline was administered instead. Animals were killed for histological examination at 4 (n = 6), 8 (n = 7), and 12 (n = 7) weeks post-denervation. Muscle atrophy was assessed using three indices: wet muscle weight, muscle fiber cross-sectional area, and the number of muscle fibers/mm(2). The effects of bortezomib were evaluated by comparing the left (L) and right (R) muscles, with sequential changes in the L/R ratio assessed. RESULTS: In saline-administered animals, atrophy of the left-sided TA and PCA muscles progressed rapidly during the first 4 weeks post-denervation, following which progression slowed. Atrophy was greater in the TA compared with the PCA muscle, although this difference was not statistically significant. In bortezomib-administered animals, atrophy of the PCA muscle was attenuated significantly at post-denervation weeks 8 and 12; no such reduction in atrophy was observed for the TA muscle.

Timing of nimodipine therapy for the treatment of vocal fold paralysis.

OBJECTIVES/HYPOTHESIS: To retrospectively determine optimal timing for initiation of nimodipine within a cohort of patients with acute vocal fold paralysis (VFP). STUDY DESIGN: Retrospective patient review. METHODS: Subjects were divided into three groups: initiation within 15 days postinjury (n = 19), between 15 and 30 days postinjury (n = 23), or greater than 30 days postinjury (n = 11). RESULTS: Fifty-one patients (53 paralyzed vocal folds [VFs]) met entrance criteria and were offered and started off-label nimodipine treatment. Thirty-six of 53 VFs recovered purposeful motion (67.9%). There was no significant difference in the rate of VF recovery among patients who began nimodipine within 15 days (68.4%), patients who started nimodipine between 15 and 30 days (73.9%) of nerve injury (P = .1405), and patients who initiated nimodipine after 30 days postinjury (54.5%). CONCLUSIONS: Nimodipine treatment for acute VFP yielded equal VF motion recovery rates regardless of when the medication was initiated. Time to recovery of motion was not different between groups studied.

Construction of Human Hepatocyte Growth Factor Gene Recombinant Lentivirus Vectors and Its Expression in MyobIasts / 听力学及言语疾病杂志

Objective To construct a gene recombinant lentiviral vector pCMV -G -U6 -hHGF and detect its expression in C2C12 myoblast cells .Methods hHGF gene fragments were obtained and purified by RT -PCR method ,and were cloned to pCMV -G&NR -U6 ,then the restructured lentiviral vector was transformed into e . coli DH5 alpha ,the positive colonies were identified by BamHI and Hind Ⅲ enzyme digestion .The selected positive colonies were tested by PCR and sequencing analysis .The expression plasmids and packing plasmids were co -trans_fected into 293 T cells ,and virus titer was observed under the fluorescence microscope .Furthermore ,transfected C2C12 cells with lenti virus ,and the expression of HGF was detected by PCR and WB methods .ResuIts PCR and sequencing analysis showed that the lentiviral vector was constructed correctly and successfully ,the virus titer was above 1 x 109 IU/mL .The results of PCR and WB showed that HGF expression level in the lentiviral vector group was much higher than those of in blank control and negative control groups ,and yet the expression was stable after 72 hours .ConcIusion The lentiviral vector pCMV -G﹠NR -U6 -hHGF has been successfully constructed ,and stable expressed in C2C12 cells .It provides references for experimental study in the fields of the denervated skeletal muscle fibrosis and nerve regeneration treatment .