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S Nasri

Publications and source records attributed to S Nasri.

At least 19 recordsLinked to original sources
PubMed2006

Postsphaleron baryogenesis.

We present a new mechanism for generating the baryon asymmetry of the Universe directly in the decay of a singlet scalar field S(r) with a weak scale mass and a high dimensional baryon number-violating coupling. Unlike most currently popular models, this mechanism, which becomes effective after the electroweak phase transition, does not rely on the sphalerons for inducing a nonzero baryon number. CP asymmetry in S(r) decay arises through loop diagrams involving the exchange of W+/- gauge bosons and is suppressed by light quark masses, leading naturally to a value of eta(B) approximately 10(-10). The simplest realization of this idea which uses a six quark DeltaB=2 operator predicts colored scalars accessible to the CERN Large Hadron Collider and neutron-antineutron oscillation within reach of the next-generation experiments.

Journal Article↗
PubMed1997

Physiologic motion after laryngeal nerve reinnervation: a new method.

In this study a new method of reinnervation for unilateral recurrent laryngeal nerve paralysis was performed in canines, producing physiologic vocal fold motion in each of a small series of animals. During the procedure the left anterior division of the recurrent laryngeal nerve was reinnervated with axons from the thyroarytenoid branch of the contralateral recurrent laryngeal nerve. The posterior branch of the left recurrent laryngeal nerve was divided and sutured to the ansa cervicalis to maintain tone in the posterior cricoarytenoid muscle. In all four animals, the right distal vocalis stump was reinnervated with an ansa cervicalis nerve branch. After 3 months physiologic vocal fold motion and electromyographic activity could be demonstrated during mechanical stimulation of the supraglottis (adduction) and during tracheostomy obstruction (abduction). Acoustic data revealed improvement of jitter, shimmer, signal-to-noise ratio, and vocal efficiency in reinnervated animals compared with paralyzed canines before treatment, although the results lacked statistical significance. This approach to the rehabilitation of unilateral vocal fold paralysis is discussed.

Acoustics↗
PubMed1997

Cross-innervation of the thyroarytenoid muscle by a branch from the external division of the superior laryngeal nerve.

The neuroanatomy of the larynx was explored in seven dogs to assess whether there is motor innervation to the thyroarytenoid (TA) muscle from the external division of the superior laryngeal nerve (ExSLN). In 3 animals, such innervation was identified. Electrical stimulation of microelectrodes applied to the ExSLN resulted in contraction of the TA muscle, indicating that this nerve is motor in function. This was confirmed by electromyographic recordings from the TA muscle. Videolaryngostroboscopy revealed improvement in vocal fold vibration following stimulation of the ExSLN compared to without it. Previously, the TA muscle was thought to be innervated solely by the recurrent laryngeal nerve. This additional pathway from the ExSLN to the TA muscle may have important clinical implications in the treatment of neurologic laryngeal disorders such as adductor spasmodic dysphonia.

Animals↗
PubMed1996

Combined use of superpulsed carbon dioxide laser and cryotherapy for treatment of facial rhytids.

OBJECTIVE: To compare the effect of superpulsed carbon dioxide (CO2) laser alone with that of cryotherapy in combination with CO2 laser in treatment of facial rhytids. DESIGN: A randomized prospective study. SETTING: Facial Plastic Surgery Clinic at Standford University Medical Center, Standford, Calif. PATIENTS: Twenty patients with perioral rhytids were randomized in the study, 11 in the laser group and 9 in the cryotherapy and laser group. INTERVENTION: Patients in the laser group were treated with superpulsed CO2 laser. Initially, the shoulders of rhytids were spot treated. The area was then wiped and rehydrated. The entire surface was then treated with a second pass. A third pass, if deemed necessary, was then used to treat the shoulders. Patients in the combined group underwent cryotherapy of the entire perioral region followed by CO2 laser treatment similar to that previously described. MAIN OUTCOME MEASURE: Improvement in facial rhytids with laser treatment alone was compared with improvement using cryotherapy and laser. A skin wrinkle grading system was used and patients were graded by 3 independent observers. Close-up photographs were obtained preoperatively and postoperatively. A questionnaire was filled out by each patient 1 month following treatment and was used to rate overall patient satisfaction. RESULTS: There was no statistically significant difference between the 2 groups regarding final outcome, amount of anesthetic agents required for each patient, or rate of complications. CONCLUSION: Superpulsed CO2 skin resurfacing alone is as effective as combined cryotherapy and superpulsed CO2 laser for treatment of perioral rhytids.

Cryotherapy↗
PubMed1996

Characteristics of an in vivo canine model of phonation with a constant air pressure source.

Many previous studies of laryngeal biomechanics using in vivo models have employed a constant air How source. Several authors have recently suggested that the lung-thorax system functions as a constant pressure source during phonation. This study describes an in vivo canine system designed to maintain a constant peak subglottic pressure (Psub) using a pressure-controlling mechanism. Increasing levels of recurrent laryngeal nerve (RLN) stimulation resulted in a significant rise in resistance followed by a plateau. For a given Psub, flow decreased significantly and precipitously with increasing stimulation and then quickly plateaued. Vocal intensity increased with increasing RLN stimulation until a peak was reached. After this peak, intensity dropped until a plateau was reached, corresponding to the flow minimum. At a given Psub, increasing levels of RLN stimulation resulted in a normal distribution of vocal efficiencies.

Airway Resistance↗
PubMed1996

Transpharyngeal approach to base of tongue tumors: a comparative study.

Tumors of the tongue base have been traditionally removed by resecting the mandible or using a translabial transmandibular approach. These procedures involve significant morbidity including lip and chin scars, malocclusion, compromised deglutition, chronic aspiration, and altered speech articulation. Therefore alternative techniques have been described to minimize the morbidity associated with transmandibular tongue resection. A retrospective analysis of patients with base of tongue tumors treated at the University of California, Los Angeles, Medical Center between 1981 and 1994 was undertaken. Thirteen patients were treated using a transpharyngeal approach compared with 18 patients who underwent a transmandibular resection. There was no difference in terms of survival or tumor-free margins. However, there was a significant difference in function (P < .05). Patients who underwent transpharyngeal resection had significantly better speech and swallowing and less aspiration compared with those who underwent transmandibular resection of tumors.

Adult↗
PubMed1995

Pediatric rhabdomyosarcoma of the head and neck.

The optimal treatment for most patients with pediatric rhabdomyosarcoma (RMS) of the head and neck has been shown to be a combination of surgery, chemotherapy and radiation therapy. A retrospective review of patients seen at our institution is presented to analyze the impact of multimodality treatment on survival in 32 pediatric RMS patients. Sixty-five percent (21/32) of the patients were disease free at the most recent follow-up. The 5 year disease free survival was 57% (17/30). Combined modality treatment in 25 patients consisting of chemotherapy, radiation therapy and surgical resection (in 5 patients) rendered 18 (72%) patients free of disease. Only 1 of 7 (14%) patients who underwent surgery alone as primary management was cured. Two of these 7 patients were salvaged, both with combined modality treatment. The Intergroup Rhabdomyosarcoma Study (IRS) protocols have resulted in increased survival in pediatric patients with RMS of the head and neck. Our results reflect the significant improvement since the IRS study was completed.

Adolescent↗
PubMed1995

Treatment of vocal fold granuloma using botulinum toxin type A.

Contact granuloma of the vocal folds has been associated with abnormal use of the voice, and acid reflux may exacerbate the inflammatory process. Treatments have included voice therapy and antireflux measures. Surgical excision is considered in patients who do not respond to medical management. Localized injections of botulinum toxin type A (BOTOX) have been effective in patients with disorders of muscular control in the head and neck. In this study, granulomas resolved in six patients who underwent injection of the affected vocal folds. Botulinum toxin type A is probably successful because it prevents forceful closure of the arytenoids during phonation and coughing. Localized injection of this neurotoxin is promising both as an initial treatment and as an alternative treatment in patients who do not respond to standard therapy or who are poor surgical candidates.

Adult↗
PubMed1995

Relation of recurrent laryngeal nerve compound action potential to laryngeal biomechanics.

This study was designed to investigate the compound action potential (CAP) of the recurrent laryngeal nerve (RLN) and to correlate this electrophysiologic signal to laryngeal biomechanics and phonatory function. Four adult mongrel canines were anesthetized. The RLN was isolated and stimulated, and recording electrodes were applied. The electromyographic (EMG) electrode was placed in the thyroarytenoid (TA) muscle. The RLN CAP and the EMG of the TA muscle were recorded and compared to the stimulation intensity, subglottic pressure (Psub), and each other. The CAP peak-to-peak and EMG peak-to-peak amplitudes demonstrated a sigmoidal relation to stimulus intensity and a linear relation to Psub and to each other. On the basis of these findings, the RLN CAP appears to be a reliable physiologic measure of laryngeal function.

Action Potentials↗
PubMed1994

Noninvasive measurement of traveling wave velocity in the canine larynx.

Laryngologists have long recognized that assessment of the mucosal wave is an important part of laryngeal evaluation. This is the first report of a noninvasive measurement of vocal fold displacement velocity in an in vivo canine model. A newly developed calibrating endoscopic instrument capable of measuring distances on the vocal fold surface is described. Displacement velocity was determined in three dogs and compared to physiologic measures in the in vivo phonation model. The results indicate that the calculated displacement velocity is linearly proportional to traveling wave velocity and fundamental frequency. Because traveling wave velocity has been shown to reflect vocal fold stiffness, this method may advance the usefulness of stroboscopy for the study of mucosal wave abnormalities.

Animals↗
PubMed1994

Function of the interarytenoid muscle in a canine laryngeal model.

The interarytenoid (IA) muscle has rarely been studied in the living larynx. In this work, the role of the IA muscle in phonation was studied in three dogs by means of an in vivo phonation model. The isolated action of the IA muscle was studied by sectioning and stimulating its nerve branch. As IA activity increased, subglottic pressure increased significantly until a plateau was reached. In the absence of superior laryngeal nerve stimulation, the fundamental frequency rose with increasing IA activity. In the presence of superior laryngeal nerve stimulation, however, no significant change in fundamental frequency was observed with increasing IA activity. Measurement of adductory force demonstrated that the IA muscle adducts primarily the posterior vocal fold. In this canine model, phonation was not possible without IA stimulation, owing to a large posterior glottic chink.

Analysis of Variance↗
PubMed1994

A pressure-regulated model of normal and pathologic phonation.

Recent evidence suggests that the lung-thorax system functions as a constant pressure source during phonation. However, previous animal models used a constant flow source. This article describes an in vivo canine model that maintains a constant subglottic pressure during phonation to more closely simulate the pulmonary system. At any given subglottic pressure, increasing levels of recurrent laryngeal nerve stimulation resulted in a significant rise in resistance followed by a plateau. Increasing levels of superior laryngeal nerve stimulation, however, produced no significant change in glottal resistance. Three experimental conditions were studied: normal, unilateral recurrent laryngeal nerve paralysis, and paralysis followed by arytenoid adduction. In normal canines, maximal vocal efficiency values were the highest, indicating the best match between pressure and resistance. The vocal efficiency values were significantly lower in recurrent laryngeal nerve paralysis, indicating pressure-resistance mis-match. Arytenoid adduction increased the maximal vocal efficiency values and decreased the mismatch observed in the paralyzed state. These findings may provide insight into an understanding of normal and pathologic laryngeal behavior.

Airway Resistance↗
PubMed1994

Effects of arytenoid adduction on laryngeal function following ansa cervicalis nerve transfer for vocal fold paralysis in an in vivo canine model.

Laryngeal reinnervation with the ansa cervicalis has been proposed as a treatment for human unilateral vocal fold paralysis (UVFP). This study tested the assumption that results from reinnervation could be improved if combined with medialization surgery. Six canine subjects underwent recurrent laryngeal nerve section and reinnervation with a branch of the ansa cervicalis. After reinnervation, vocal function was assessed before and after arytenoid adduction. Although laryngeal function improved significantly following reinnervation, results were significantly enhanced by the addition of medialization surgery. The implications for the treatment of human unilateral vocal fold paralysis are discussed.

Animals↗
PubMed1994

Malignant melanoma of cervical and parotid lymph nodes with an unknown primary site.

Forty-six patients with malignant melanoma metastatic to cervical or parotid lymph nodes with an unknown primary site were treated at UCLA Medical Center from 1964 through 1991. Treatment consisted of parotidectomy and/or neck dissection with or without adjuvant therapy. The initial presentation was a cervical mass in 74% and a parotid mass in 26% of patients. Metastasis distal to the head and neck nodal basins developed in 22% of patients. Involvement of more than four cervical or parotid nodes resulted in a significant increase in distant metastasis (P < .01). Adjuvant therapy was found to have no significant effect on survival rates. However, age at the time of diagnosis influenced the survival rates. The significance of the improved survival of these patients as compared to those with a known primary melanoma is discussed.

Adolescent↗
PubMed1994

Measurement of adductory force of individual laryngeal muscles in an in vivo canine model.

In this experiment, the adductory properties of three intrinsic laryngeal muscles (the thyroarytenoid [TA], lateral cricoarytenoid [LCA], and interarytenoid [IA]) were studied and quantified. Using an in vivo canine laryngeal model, a recently developed "tensionometer" was used to measure the adductory force produced by each of these muscles at the vocal process of the arytenoid. Isolated muscle activation was obtained by stimulating selective terminal branches of the anterior division of the recurrent laryngeal nerve. Results indicate that the LCA is the strongest adductory muscle, followed by the TA and the IA. Videolaryngoscopy revealed that LCA contraction causes adduction of the vocal fold and vocal process, with the predominant effect on the process. TA stimulation leads primarily to adduction of vocal fold, and the IA adducts mainly the vocal process. Implications of these findings are discussed.

Animals↗