Biomedical subjects

M Natividad

Publications and source records attributed to M Natividad.

13 recordsLinked to original sources

PubMed1992

Videostroboscopy of human vocal fold paralysis.

Previous stroboscopic studies of human vocal cord paralysis have been infrequent and have lacked documentation of the site of lesion. In order to study human laryngeal paralysis, the recurrent and superior laryngeal nerves were infiltrated unilaterally with lidocaine hydrochloride in three human volunteers. Vagal paralysis was simulated by combined (superior and recurrent) infiltration in one volunteer. Additionally, 20 patients with untreated laryngeal paralysis were studied from the voice laboratory at UCLA. In addition to videostroboscopic analysis, photoglottography and electroglottography were performed and synchronized with the stroboscopic images. The most significant finding in stroboscopy of the paralyzed larynx was the asymmetry of traveling wave motion. The traveling wave on the normal vocal fold had a faster wave velocity that created a phase difference in the vibration of the two folds. The wave also traversed a greater distance along the vocal fold mucosa on the normal side. No patient or volunteer with untreated laryngeal paralysis had a symmetric traveling wave, either in superior or recurrent laryngeal nerve paralysis. Synchronization with glottography indicated that the differentiated electroglottographic waveform provides useful information about the timing of glottic opening and closure in states of asymmetric laryngeal vibration. Implications for future studies and for the diagnosis of laryngeal paralysis are discussed.

Adult↗

PubMed1992

Physiologic motion after vocal cord reinnervation: a preliminary study.

This study attempted to reestablish physiologic vocal cord motion, rather than synkinesis, to a reinnervated vocal cord. One mongrel dog underwent a division and reanastomosis of the anterior branch of the right recurrent laryngeal nerve and simultaneous separation and reimplantation of a posterior division nerve-muscle pedicle into the posterior cricoarytenoid muscle. After 21 weeks, spontaneous physiologic vocal cord movement and electromyographic (EMG) activity were recorded during respiratory obstruction and laryngeal mechanical stimulation. Acoustic measures and histologic data are also presented from the reinnervated and normal vocalis muscle and from the recurrent laryngeal nerve. This study demonstrated that physiologic vocal cord motion can be achieved after laryngeal reinnervation using this technique.

Anastomosis, Surgical↗

PubMed1991

A new technique for quantitative measurement of laryngeal videostroboscopic images.

The objective measurement of laryngeal function and pathophysiology is one of the goals of current laryngeal research. We describe a new computerized tool for voice analysis systems that allows the quantitative analysis of individual videostroboscopic images. We describe this new technique compared with previous methods of videostroboscopic image analysis and discuss its clinical and research applications.

Humans↗

PubMed1991

Experimental evidence in the in vivo canine for the collapsible tube model of phonation.

The in vivo canine model of the larynx was used to measure transglottic pressures and airflow during phonation. Conditions of supraglottal resistance were also simulated. Pressure drop-flow curves were compared with data on collapsible tubes. The in vivo in canine model of the larynx demonstrates a number of features similar to oscillation in collapsible tubes.

Air Movements↗

PubMed1990

The effect of air flow and medial adductory compression on vocal efficiency and glottal vibration.

This study used an in vivo canine model to investigate the effects of varying vocal fold resistance by electrically stimulating the recurrent laryngeal nerve while monitoring medial adductory compression of the vocal folds, glottal airflow, and vocal intensity. The effects of increasing airflow on glottal vibration were also examined stroboscopically and by measurement of open quotient. The results indicated that increasing intensity by medial adductory compression was more efficient than by increasing airflow. Increasing airflow produced a significantly greater open quotient and vocal fold vibratory excursion.

Animals↗

PubMed1990

Regional blood flow of the canine vocal cord: the microsphere surface technique.

The vocal fold's microcirculation has been well described, but there are few reports regarding the blood flow to this region. A number of methods have been used to evaluate the blood flow to an organ system. Among the most sensitive is the microsphere surface technique, which has been used to measure blood flow in many organ systems, including the cochlea. In this study, the blood flow to the canine vocal fold was assessed using the microsphere surface technique. Overall flow was measured, as well as flow to the lamina propria and muscularis layers. The technique and the results are reported.

Animals↗

PubMed1989

Office-based system for voice analysis.

There has been recent growing interest in the analysis of various electronically recorded signals as potential tools for objective assessment of vocal dysfunction. In the past, analysis of such signals required an expensive multitrack FM recorder, mainframe computer system, customized software, and significant time commitment. This report describes an adaptation of commercially available components that allow digital recording of multiple electronic signals, storage of data, and subsequent signal analysis using an inexpensive personal microcomputer system. Commercially available software for manipulation and examination signals is discussed as adapted for examination of glottographic and acoustic signals. The relatively inexpensive availability of similar computer systems will, hopefully, encourage assessment of the clinical applications of objective techniques of voice quality.

Analog-Digital Conversion↗

PubMed1989

Renin release responses to in vitro prostaglandin challenge in the summer-active ground squirrel, Spermophilus lateralis.

1. Using a renal cortical slice preparation from the summer-active ground squirrel, Spermophilus lateralis, resting renin release (RR) and tissue cyclic AMP content (TcAMPC) levels were found to be significantly higher and lower, respectively, than those previously reported for its hibernating counterpart. 2. At a 10(-5) M dose, PGE2 but not PGE1, PGF2-alpha or PGA1, significantly stimulated RR in the summer-active ground squirrel (SAGS). 3. Addition of agents which normally increase TcAMPC significantly potentiated the effect of PGE1, while preventing that of PGE2, on RR and TcAMPC. 4. Opposite TcAMPC changes may mediate the in vitro RR responses to PGE1 and PGE2 administration in the SAGS.

Alprostadil↗

PubMed1989

Regional blood flow to the canine vocal fold at rest and during phonation.

Recent reports have suggested that blood flow to the vocal fold decreases during phonation. However, these studies relied on indirect measures of blood flow, such as tissue oxygen tension. Among the differing methods of measuring blood flow, one of the most sensitive is the microsphere surface technique. This technique has been effective in assessing the overall and regional blood flow to a number of different organs, including the cochlea. Employing an in vivo canine model, we injected microspheres into the left atrium. From there, they were distributed and became entrapped in the tissues in proportion to blood flow. We measured the blood flow to the entire vocal fold, as well as the lamina propria and muscularis layers. The results revealed a statistically significant (p less than .002) increase in blood flow on phonation. The increase, however, was due to increased flow to the muscularis layer. The flow to the lamina propria remained unchanged during phonation.

Animals↗

PubMed1989

The effect of recurrent laryngeal nerve stimulation on phonation in an in vivo canine model.

The present investigation was designed to examine the effect of variation in recurrent laryngeal nerve stimulation (RLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three fundamental frequencies (F0) (100 Hz, 130 Hz, and 160 Hz) for RLNS, using a constant rate of air flow. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the open quotient (OQ), and an increase in the closing quotient (CQ). Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS.

Animals↗

PubMed1986

Prostaglandin E1 (PGE1) stimulates in vitro renin release in the hibernating ground squirrel.

Using a renal cortical slice preparation obtained from hibernating ground squirrels, this study investigated whether three major intrarenal prostaglandins (PG) and other agents added at a 10(-5) M dose can affect renin release (RR), and if their effect on RR is correlated with changes in tissue cyclic AMP content (tcAMPc). Resting in vitro levels for RR and tcAMPc during hibernation were found to be comparable to those observed in non-hibernating (NH) mammals. Addition of PGE1 significantly stimulated RR while PGE2 and PGF2-alpha were ineffective. None of the three PG's tested altered resting levels of tcAMPC. When added by itself or in conjunction with any of the three PG's, the phosphodiesterase inhibitor theophylline did not modify resting levels of RR and tcAMPc, but it prevented the previous stimulatory effect of PGE1 alone on RR. Addition of lipid-soluble dcAMP, either alone or in conjunction with any of the three PG's, resulted in an increase in tcAMPc in all instances, no change in resting RR regarding PGE2 and PGF2-alpha, and again the prevention of the stimulatory effect of PGE1 alone on RR. These data suggest that: the resting activity of the renin-angiotensin system (RAS) and the adenylate cyclase-cAMP system (AC-cAMP) of the hibernating ground squirrel is comparable to that of NH species; in contrast, the sensitivity of the RAS of the hibernator to PG stimulation is less than that exhibited by the RAS of NH species when comparable in vitro concentrations of three major PG's are used; PGE1 stimulation of RR in the hibernator is independent of changes in tcAMPc; changes in tcAMPc may be inversely related to those in RR in the hibernator; and the known stimulatory effect of PG's on the renal cortical AC-cAMP of NH species is not seen in the hibernating ground squirrel at comparable PG doses.

Adenylyl Cyclases↗

PubMedDate not supplied

Effect of superior laryngeal nerve stimulation on phonation in an in vivo canine model.

We investigated the effect of variation in superior laryngeal nerve stimulation (SLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three SLNS frequencies (100 Hz, 130 Hz, and 160 Hz) using a constant rate of air flow. Increasing SLNS, which causes a contraction of the cricothyroid muscle, produced a marked increase in Fo, little change in Psub, an increase in the open quotient, and a decrease in the closed quotient of the glottal cycle.

Animals↗

PubMedDate not supplied

Synchronizing videostroboscopic images of human laryngeal vibration with physiological signals.

PURPOSE: This report describes a new system that permits the precise correlation of videostroboscopic images with corresponding physiological measures, such as glottography and subglottic pressure. METHOD: A healthy volunteer had unilateral vocal cord paralysis induced by infiltrating local anesthesia into the recurrent and superior laryngeal nerve. Vocal-fold vibrations were monitored by photoglottography (PGG) and electroglottography (EGG). Analog signals from the EGG and PGG were synchronized with the video and correlated. RESULTS: The method described permits images to be sampled throughout sustained phonation. This technique allows study of events during glottic vibration. Results obtained have been in close agreement with previous studies that correlate the vocal-fold morphology to glottographic signal using other methods. This technique is inexpensive in comparison with high-speed filming. The main disadvantage of this method is related to the limitations of stroboscopy.

Adult↗