Revisits after adenotonsillectomy in children with sleep-disordered breathing: A retrospective single-institution study.

OBJECTIVE: To investigate emergency room (ER) revisits and hospital readmissions following adenotonsillectomy (T&A) in children with sleep-disordered breathing (SDB), and correlations between SDB severity and ER revisits. DESIGN: Retrospective chart review study. SETTING: Tertiary referral centre. PARTICIPANT: 610 consecutive children underwent T&A for treating SDB. MAIN OUTCOME MEASURES: Sleep-disordered breathing severity was defined according to the apnoea-hypopnoea index (AHI) (primary snoring = AHI < 1; mild = AHI 1-5; moderate = AHI 5-10; and severe = AHI > 10). Revisit and readmission patterns within 30 days of the surgery were extracted and analysed. RESULTS: Of these children (mean age = 7.2 years; males = 72%), 49 (8.0%) had first ER revisit, nine (1.5%) had second ER revisits, and one (0.2%) had third ER revisits. Reasons for ER revisits were bleeding related (46%) or non-bleeding related (54%). The timing for revisits was 6.9±1.9 postoperative days for bleeding-related revisits and 9.3±10.0 days for non-bleeding-related revisits. Treatment strategies during these revisits were treat and release in 44 children (74.6%), admission for observation in eight children (13.5%), and admission for surgery in seven children (11.9%). The incidence of ER revisit and hospital readmission was similar among children with all levels of SDB severity. Multivariable logistic regression analysis showed that young children (<3 years) experienced an increased risk of non-bleeding-related revisits (odds ratio [OR] = 4.1). CONCLUSIONS: Children with severe SDB do not experience increased risks of revisit or readmission; however, young children are at increased risk of non-bleeding-related revisits.

Simultaneous typical carcinoid tumour of larynx and occult papillary thyroid carcinoma.

Typical carcinoid tumour of the larynx is extremely rare. We report the case of a 43-year-old man initially diagnosed with typical carcinoid tumour of the larynx, presenting with a foreign body sensation in his throat. Coincidentally, an occult papillary thyroid carcinoma was diagnosed, following detection of a suspicious lymph node on pre-operative imaging studies, and confirmation by neck dissection and subsequent total thyroidectomy. Following surgery and radioiodine therapy for these cancers, the patient was alive, well and free of disease two years later. Typical carcinoid tumour of the larynx with a synchronous occult papillary thyroid carcinoma has not previously been reported. The optimal treatment strategy for this case is also discussed.

Resonance frequency in patellar tendon.

The aim of this study was to the measure resonance frequency of the patellar tendon in order to determine whether the resonance frequency exists in the soft tissue of the human body. A vibrator was attached to the medial aspect of the tibia of 10 healthy subjects to provide different frequencies of vibration, and an accelerometer was attached to the patellar tendon to measure the vibration of the patellar tendon. Measurements were obtained at 0 degrees , 60 degrees and 90 degrees of knee flexion. A mean resonance frequency of 22.5+/-0.8, 23.0+0.7 and 24.0+0.8 Hz was produced in the right patellar tendon when the knee joint was at 0 degrees , 60 degrees and 90 degrees of flexion, respectively. The increase in resonance frequency from 0 degrees to 60 degrees was not statistically significant. However, the increase from 60 degrees to 90 degrees was significant (P<0.05). No differences in the measured parameters were evident for the left and right patellar tendons. These results indicate that resonance frequencies exist in soft tissues of the body and that this characteristic may be useful in detecting changes in soft tissue physical properties.

Noninvasive assessment of vocal fold mucosal wave velocity using color doppler imaging.

The vibratory movement of the vocal folds (VF) plays an important role in normal function of phonation. We developed a noninvasive technique to quantify the human mucosal wave velocity (MWV) in vivo using color Doppler imaging (CDI). During phonation, the motion of mucosa-air interface generates a unique pattern of US color artefacts that assist the identification of true VF location. An in vitro study using a vibrating string phantom was conducted to investigate how the CDI displayed a vibrating soft tissue at high frequency. The vibrating amplitude, frequency, mass density and the acoustic impedance of the soft tissues were found to dominate the formation of color artefacts. Based on the model of finite string with fixed ends, we estimated the mean MWV for 10 adult volunteers (6 men, 4 women, ages 34 +/- 5 years) with normal VF function. The mean MWVs for the men were found to vary from 2.1 to 10 m/s in a frequency range of 85 to 310 Hz at their comfortable pitch and intensity, and the women typically had higher MWVs that varied from 5.0 to 16.5 m/s in a frequency range of 180 to 480 Hz. The MWV increased linearly with the frequency and there was no observable difference in mucosa stiffness due to the effect of gender. The variation in MWV as it propagates vertically can be seen from the color and shape of the artefacts. The VF polyp resulted in abnormal MWV and different CDI vibratory artefacts. The CDI artefacts provide insight on the dynamics of mucosa structure during phonation, and the method presented is promising for noninvasive monitoring of laryngeal functions clinically.

Inducing vocal register transition in an in vivo evoked phonation canine model.

BACKGROUND AND PURPOSE: The nature of vocal registers is still a subject of controversy. The purpose of this study was to demonstrate the induction of timbre transition of vocal register in an in vivo evoked phonation canine model and thereby confirm vocal register transition as a laryngeal event. MATERIALS: A canine midbrain stimulation evoked phonation model was used in this study. To repeat a low-pitched evoked phonation in the model, the low activity of the thyroarytenoid (TA) muscle and coordinate actions of other intrinsic laryngeal muscles were kept in a consistent condition by stimulating the same midbrain point with the same electric current intensity at the same timing in the respiratory cycle. The cricothyroid (CT) muscle was activated with an electrical current delivered directly to the muscle during the evoked phonation. Under constant subglottal pressure, CT muscle activity was varied while changes in vocal register of the evoked phonation were monitored. RESULTS: The fundamental frequency (F0) of the evoked phonation increased as the stimulating current to the CT muscle increased. In addition to the increase in F0, data collected from six animals demonstrated that timbre register transition was induced by a stepwise increase of current to the CT muscle. The abrupt escalation of F0 and sudden change in sound quality, which could be verified perceptually, manifested the register transition. Frequency spectrum analysis showed that the sound in the modal register contained abundant harmonics that were different from those of the sound in the falsetto register, which contained fewer harmonics. CONCLUSION: The results of this study indicated that intrinsic laryngeal muscles (especially CT and TA muscle interactions) regulate timbre-register transition in a canine model.

Soluble adhesion molecules and cytokines in tumor-associated tissue eosinophilia of nasopharyngeal carcinoma.

The phenomenon of tumor-associated tissue eosinophilia (TATE) is seen in some cases of nasopharyngeal carcinoma (NPC) and is characterized by the eosinophils breaking through the vascular wall and pervading the tumor stroma. The margination and trans-endothelial migration of eosinophils in a typical inflammatory reaction depend on the activating effects of certain cytokines and the expression of adhesion molecules on the eosinophils and endothelial cells. In order to investigate whether the adhesion molecules and activating cytokines play a role in eosinophil tumor infiltration, we measured the serum levels of 3 adhesion molecules, intercellular adhesion molecule-1, E-selectin and vascular cell adhesion molecule-1, and 2 cytokines, IL-3 and IL-5, in 60 NPC patients and 40 normal healthy subjects. We found that the NPC patients had higher serum levels of all three soluble adhesion molecules than the normal subjects but the levels of adhesion molecules failed to correlate with the TATE phenomenon. The levels of IL-3 and IL-5 appeared not to differ between the NPC and control groups. We postulate that the three soluble adhesion molecules do not play a major role in TATE and that their elevation in serum may be due to local and/or systemic immune responses.

Noninvasive assessment of laryngeal phonation function using color Doppler ultrasound imaging.

Color Doppler imaging (CDI) was used to identify the morphology of vocal folds (VF) and to quantify the tissue horizontal displacement velocity (HDV) in the vibrating portion of VF. Mucosal HDV that gives an estimate of the stiffness of the VF cover is very important clinically. The VF and its cover were shown to be very hypoechoic and not adequately visible in B-scan image. However, in this study, we found that the structure of the true VF, especially the mucosa and the superficial layer of the lamina propria, the so-called "cover," can be easily identified and evaluated using CDI. The mean VF displacement velocity was measured by decoding the pseudocolor codes of the ultrasound (US) image at the vibrating sites. The mucosal mean HDV obtained from 10 normal men of age 34 +/- 8 years phonating at their most comfortable pitch and intensity (98 +/- 12 Hz, 55-65 dB) was about 68 +/- 10 cm/s, which agreed reasonably with the literature. Therefore, the CDI could be used as a potential tool for assessing the phonation function in the larynx nonintrusively.

The effect of cricothyroid muscle action on the relation between subglottal pressure and fundamental frequency in an in vivo canine model.

The relation between subglottal pressure (Ps) and fundamental frequency (F0) in phonation was investigated with an in vivo canine model. Direct muscle stimulation was used in addition to brain stimulation. This allowed the Ps-F0 slope to be quantified in terms of cricothyroid muscle activity. Results showed that, for ranges of 0-2 mA constant current stimulation of the cricothyroid muscle, the Ps-F0 slope ranged from 10 Hz/kPa to 60 Hz/kPa. These results were compared to similar slopes obtained in a previous study on excised larynges in which the vocal fold length was varied instead of cricothyroid activation. A physical interpretation of the Ps-F0 slope is that the amplitude-to-length ratio of the vocal folds decreases with CT activity, resulting in a smaller time-varying stiffness. In other words, there is less dependence of F0 on amplitude of vibration when the vocal folds are long instead of short.

Immunological effects of long-term lead exposure among Taiwanese workers.

Exposure to lead has been shown to have a deleterious effect on the immune system. However, the findings of previous studies have been inconsistent. This may have been due to the increased susceptibility to intracellular pathogens and increased polyclonal and antigen-specific responses on exposure to lead. The objective of the current study was to evaluate the immune function of long-term workers with lead in a battery manufacturing plant. Junior high school teachers were used as a control group. Our results showed that the percentage of monocytes was significantly higher among lead workers than in the control group, but T8 cell levels were lower. The T4/T8 ratio was significantly higher among lead workers (1.42) than in the control group (1.18). After adjustment for age, gender and disease using multiple linear regression models, the percentage of B-cells and number of lymphocytes, monocytes and granulocytes were all significantly decreased among lead workers compared with the control group. Our findings showed that lead caused a marked immunotoxic and immunosuppressive effect among long-term lead workers.

Vocal fold abnormalities in laryngeal tension-fatigue syndrome.

This study sought to use videostrobolaryngoscopy to clarify possible biomechanical causes of dysphonia in patients with laryngeal tension-fatigue syndrome, a chronic functional dysphonia due to vocal abuse and misuse. The videostrobolaryngoscopic records of 301 laryngeal tension-fatigue syndrome patients were reviewed. The focus of observation was the visual characteristics of the mucus layer, vessel dilatation or neovascularization on the surface of vocal folds, abnormal glottal closure, and bilateral vibratory asymmetry. Abnormal findings on the vocal folds, especially during vibration, were noted in 270 cases (89.7%). Most patients (222, 73.8%) had multiple abnormalities. The results of this study suggest that chronic vocal overuse under excessive laryngeal muscle tension can cause phonotrauma and result in biomechanical property changes in the vocal fold's cover. These changes would hinder the regular vibration of the vocal folds, increase irregularities in voice signals, and worsen the symptoms of dysphonia.

Matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 gene expressions and their differential regulation by proinflammatory cytokines and prostaglandin in nasal polyp fibroblasts.

Chronic inflammation of the paranasal sinus leads to nasal polyp (NP) formation. In this study, we investigated the effect of stimulation of the proinflammatory cytokines interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) and prostaglandin (PG) E2 on the production of messenger RNA (mRNA) of matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-I (TIMP-1) in nasal polyp fibroblasts (NPFs) and nasal mucosa fibroblasts (NFs). The mRNAs of IL-1alpha, TNF-alpha, MMP-1, and TIMP-1 in 40 surgical specimens of NPs were studied by in situ hybridization to corroborate the in vitro findings. The results indicated a significant amount of constitutive MMP-1 mRNA in NPFs and cytokine-induced MMP-1 steady-state mRNAs in NFs. The effect of stimulation of cytokines on TIMP-1 mRNA synthesis was unremarkable in NPFs and NFs. Exogenous PGE2 enhanced cytokine-stimulated MMP-1 mRNA synthesis in NPFs. In situ hybridization revealed that cells expressing MMP-1 and TIMP-1 mRNAs (primarily plasma cells, fibroblasts, and endothelial cells) gathered around areas with loose stroma, suggestive of rapid extracellular matrix degradation. These data suggest that the pathogenesis of nasal polyposis could be related to production of MMP-1 and consequent promotion of matrix collagenolysis.

Dysphagia after radiotherapy: endoscopic examination of swallowing in patients with nasopharyngeal carcinoma.

Dysphagia is a late sequela compromising the lives of more than one fourth of patients with nasopharyngeal carcinoma (NPC) who survive long after radiotherapy. By using fiberoptic endoscopic examination of swallowing as a modality for dysphagia evaluation, we were able to easily recognize the functional and anatomic changes in 31 dysphagic NPC patients. The majority of patients were found to aspirate after the act of swallowing (77.4%). Seventeen (54.8%) had tongue atrophy, and 9 (29%) had vocal cord palsy. Dysfunctions such as dry mouth (45.2%), velopharyngeal incompetence (58%), premature leakage (41.9%), delay or absence of swallow reflex (87.1%), poor pharyngeal constriction (80.6%), pharyngeal residue retention (83.9%), penetration or aspiration (93.5%), and silent aspiration (41.9%) were noted in these patients. Multiple dysfunctions were demonstrated in each patient. Abnormality of pharyngeal constriction and/or aberrant upper esophageal sphincter function played the major role in the postswallow aspiration of these irradiated NPC patients. Clinically compromised patients (weight loss of > or =5 kg in 1 year or pneumonia) had more of the above anatomic and functional impairments. The radiation dosage and volume bore no correlation to the time of symptom onset, or to the occurrence of functional changes.

Evaluation of swallowing safety with fiberoptic endoscope: comparison with videofluoroscopic technique.

Videofluoroscopy has long been viewed as the "gold standard" of swallowing examination for the comprehensive information it provides. However, it is not very efficient and accessible in some practical situations. In this study, we tried to use a modified technique of fiberoptic endoscopic examination of swallowing (FEES) in evaluating dysphagic patients. For each examination, a spoonful of pudding and dyed water were fed in sequence three times. The pharyngeal swallowing events were observed with fiberscope panoramically and videotaped. Twenty-eight chronic dysphagic patients underwent both videofluoroscopy and FEES in 2 weeks. Comparison of the results revealed that disagreements in premature oral leakage to the pharynx, pharyngeal stasis, laryngeal penetration, aspiration, effective cough reflex, and velopharyngeal incompetence were 39.3%, 10.7%, 14.3%, 14.3%, 39.3%, and 32.1%, respectively. FEES was found to be more sensitive in detecting these risky features of swallowing, except with respect to premature leakage. Possible causes of the discrepant results are discussed, and the limitation of videofluoroscopy in practical usage is discussed. FEES is conclusively a safer, more efficient, and sensitive method than videofluoroscopy in evaluating swallowing safety.

Water reuse in the L-lysine fermentation process.

L-Lysine is produced commercially by fermentation. As is typical for fermentation processes, a large amount of liquid waste is generated. To minimize the waste, which is mostly the broth effluent from the cation exchange column used for l-lysine recovery, we investigated a strategy of recycling a large fraction of this broth effluent to the subsequent fermentation. This was done on a labscale process with Corynebacterium glutamicum ATCC 21253 as the l-lysine-producing organism. Broth effluent from a fermentation in a defined medium was able to replace 75% of the water for the subsequent batch; this recycle ratio was maintained for three sequential batches without affecting cell mass and l-lysine production. Broth effluent was recycled at 50% recycle ratio in a fermentation in a complex medium containing beet molasses. The first recycle batch had an 8% lower final l-lysine level, but 8% higher maximum cell mass. In addition to reducing the volume of liquid waste, this recycle strategy has the additional advantage of utilizing the ammonium desorbed from the ion-exchange column as a nitrogen source in the recycle fermentation. The major problem of recycling the effluent from the complex medium was in the cation-exchange operation, where column capacity was 17% lower for the recycle batch. The loss of column capacity probably results from the buildup of cations competing with l-lysine for binding. (c) 1996 John Wiley & Sons, Inc.

Broth recycle in a yeast fermentation.

Fermentation is a water-intensive process requiring treatment of large amounts of effluent broth. It is desirable to increase the ratio of product produced to the volume of effluent by minimizing the discharge of effluent from the fermentation process. A study of recycling spent fermentation process. A study of recycling spent fermentation broth for the subsequent fermentation was carried out with Apiotrichum curvatum an oleaginous yeast, as the working culture. Spent broth from a defined medium was recycled t replace as much as 75% of the water and salts for subsequent batches and this was repeated for seven sequential batches without affecting cell mass and lipid production. A 64% vlume reduction of wastewater was achieved in this manner. However, when using whey permeate as the medium, lipid production dropped after three consecutive recycle operations at 50% recycle, and after two consecutive recycle operations at 75% and 100% recycle. Accumulation of ions in the broth appeared to be responsible for the inhibition. An ion exchange step was able to eliminate the ion buildup and restore fermentation performance. (c) 1994 John Wiley & Sons, Inc.

Effect of subglottic pressure on fundamental frequency of the canine larynx with active muscle tensions.

The relation between subglottic pressure and the fundamental frequency of vocal fold vibration was studied by means of evoked phonation in an in vivo canine model. The evoked-phonation model involved electrical stimulation of the midbrain that resulted in consistent responses by respiratory and laryngeal musculature, accompanied by phonation. The dynamic stiffness properties of the vocal folds, especially the "cover," were investigated by delivering various amounts of air pressure to the larynx from an opening in the trachea. The fundamental frequency of vocal fold vibration increased linearly with subglottic pressure. The slopes ranged from 22.4 to 118.7 Hz per kilopascal in 7 animals. The results indicated that the dependence of fundamental frequency on subglottic pressure is a passive mechanical phenomenon.

Modulation of fundamental frequency by laryngeal muscles during vibrato.

The variations in voice fundamental frequency (F0) that occur during vibrato production may be produced, at least in part, by modulation of laryngeal muscle activity. We have quantified this relation by using a cross-correlation analysis of the changes in F0 during vibrato and the changes either in motor unit firing rate or in gross electromyographic activity from the cricothyroid (CT) and the thyroarytenoid (TA) muscles. Two trained amateur tenors provided the data. Correlations were generally quite strong (mean r for the CT was 0.72 for singer 1 and 0.50 for singer 2; mean r for the TA was 0.31 for singer 2), thus providing support for previous evidence that fundamental frequency modulation in vibrato involves active modulation of the laryngeal motoneuron pool, especially by the CT muscle. In addition, phase delays between muscle modulation and changes in fundamental frequency were substantial (averaging approximately 130 degrees for the CT and 140 degrees for the TA). This finding may help provide insight regarding the mechanisms responsible for the production of vibrato.