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Biomedical subjects

M Broniatowski

Publications and source records attributed to M Broniatowski.

At least 19 recordsLinked to original sources
PubMed2006

Iso-branched semifluorinated alkanes in Langmuir monolayers.

A series of semifluorinated n-alkanes (SFAs), of the general formula: (CF3)2CF(CF2)6(CH2)nH (in short iF9Hn), n = 11-20 have been synthesized and employed for Langmuir monolayer characterization. Surface pressure and electric surface potential measurements were performed in addition to Brewster angle microscopy results, which enabled both direct visualization of the monolayers structure and estimation of the monolayer thickness at different stages of compression. Our paper was aimed at investigating the influence of the iso-branching of the perfluorinated fragment of the SFA molecule on the surface behavior of these molecules at the air/water interface. It occurred that iF9 SFAs with the number of carbon atoms in the hydrogenated moiety from 11 to 20 are capable of Langmuir monolayer formation. Monolayers from iF9H11 to iF9H13 are instable, whereas those formed by iF9 SFAs with longer hydrogenated chains form stable films at the free surface of water. As compared to SFAs containing perfluorinated chain in a normal arrangement, iso-branched molecules have a greater tendency to aggregate. Lower stability of monolayers formed by iF9 SFAs as compared to F10 SFAs originated from the surface nucleation observed in BAM images, even at the very initial stages of compression. The dipole moment vector for iso-branched SFAs was found to be virtually aligned with the main axis of the molecule, contrary to F10 SFAs, where the dipole moment vector was calculated to be tilted with respect to the main molecular axis. Quantitative Brewster angle microscopy measurements (relative reflectivity experiments) enabled us to monitor the changes of monolayer thickness at different stages of monolayer compression.

Journal Article↗
PubMed2004

Semifluorinated chains in 2D-(perfluorododecyl)-alkanes at the air/water interface.

Langmuir monolayers of a homologous series of perfluorododecyl-n-alkanes (general formula F(CF2)12(CH2)nH, abbreviated as F12Hn, where n = 6-20) are investigated through isotherms of surface pressure (pi) and electric surface potential (DeltaV) versus area (A) and quantitative Brewster angle microscopy. The investigated monolayers are found to be liquid in nature. The negative sign of the measured surface potential evidences the orientation of all the investigated molecules with their perfluorinated parts directed toward the air regardless of the length of the hydrogenated unit. Analysis of the direction of the molecular dipole moment with respect to the main axis indicates that the minimum effective dipole moment is achieved for a molecule oriented at an angle of about 35 degrees to the surface normal. The film thickness was evaluated from the relative intensity measurements. The results suggest that the F12Hn molecules are tilted to the interface in the vicinity of collapse, which is in accordance with the liquid character of their monolayers.

Air↗
PubMed2001

Dynamic laryngotracheal closure for aspiration: a preliminary report.

OBJECTIVES/HYPOTHESIS: An estimated 500,000 patients per year in the United States. are affected by stroke-related dysphagia. Approximately half experience aspiration, which can lead to pneumonia or death. Aspiration may result from many factors, including delayed transport of the bolus, faulty laryngeal elevation, and poor coordination or inappropriate timing of vocal cord closure. Interventions carried out to protect the lungs are usually irreversible, destructive to the upper airway, and rarely prevent the need for enteral tube feeding. STUDY DESIGN: We present a report of the first implantations of a new device in an FDA-approved study to restore dynamic laryngotracheal separation. Two stroke patients needing tracheostomy were selected based on chronic aspiration verified by clinical and radiologic criteria (modified barium swallow [MBS]). METHODS: The left recurrent laryngeal nerve was exposed and electrically stimulated to verify vocal fold adduction. Huntington Medical Research Institute Bipolar Helical Electrodes were then implanted around the nerve. The leads were tunneled and linked to a NeuroControl Implantable Receiver-Stimulator placed subcutaneously on the chest wall. Activation of the stimulator was performed through an external transmitter linked by induction. RESULTS: The device was successfully triggered intra- and postoperatively. Serial flexible fiberoptic endoscopies and MBS demonstrate that aspiration is systematically arrested using low levels of electrical stimulation (42 Hz, 48-100 microsec, 1 mA). DISCUSSION: This pioneering work has shown that aspiration can be controlled without airway damage for a wide population of neurologically impaired patients because it appears more physiological than standard therapies. CONCLUSION: Based on the first two patients, paced laryngotracheal separation is clinically effective in controlling aspiration.

Aged↗
PubMed1999

Vagal stimulation for reciprocal coupling between glottic and upper esophageal sphincter activities in the canine.

Glottic adduction couples with relaxation of the tonically contracted upper esophageal sphincter (UES) to constitute the end point of pharyngeal swallowing. Together with deglutitive laryngeal elevation, this reciprocal relationship contributes to protecting the lungs from aspiration. Degrees of uncoordination between glottic and upper esophageal sphincters can be seen under diverse circumstances of neurologic damage such as stroke, gastroesophageal reflux, and in the growing elderly population presenting with weaker musculature. We hypothesized that reciprocal coupling between glottic closure and UES relaxation may be artificially reestablished through vagal stimulation if the appropriate neural centers and their leading pathways remain capable of exciting a critical number of motor units. Orderly recruitment of the vagus nerve was produced in three dogs with a circuit superimposing 600-Hz, 3800-0-microA blocking over 10-70-Hz, 0-2300-microA stimulating currents. Amplitudes of motor unit or compound muscle action potentials were recorded from the thyroarytenoideus and cricopharyngeus via surface electromyographic electrodes. Stimulation was accompanied by a drop in UES intraluminal pressure. The reciprocal relationship between the two muscles could be time locked within certain stimulus parameters. We submit that electronic coupling between the glottic and UESs may show promise in preventing aspiration under selected circumstances.

Action Potentials↗
PubMed1999

Current evaluation and treatment of patients with swallowing disorders.

To determine the varied causes of oropharyngeal dysphagia and their respective pathophysiology, a working understanding of the normal anatomy and function of the highly integrated mechanism of swallowing is outlined. This information is presented as the basis for a reasoned and detailed approach to the history, physical examination, and endoscopic evaluation of normal and altered oropharyngeal swallowing. The management of swallowing disorders depends on the nature and magnitude of the responsible clinical condition. Conservative and surgical approaches are discussed. These modalities and their indications are described in detail.

Deglutition↗
PubMed1998

Long-term excitability and fine tuning of nerve pedicles reinnervating strap muscles in the dog.

Contraction of paralyzed striated muscles has been restored by stimulating reinnervating pedicles with currents of low intensity. In order to allow clinical application, stable, long-term excitability must emulate the parameters necessary for the stimulation of normal motor nerves. In 6 dogs, the ansa hypoglossi nerve was implanted into the contralateral denervated sternohyoid muscle and surrounded with a bipolar cuff electrode. Three of the reinnervating pedicles were chronically paced with a Medtronic Itrel II Multiprogrammable Pulse Generator (0.5 V, 0.2 second on [30 pulses per second, 0.21-millisecond pulse width], 2.9 seconds off). At reexploration after 8 months (6 months for 1 dog), frank contraction confirmed by electromyography tracings occurred in all animals with currents in the range of 0.1 to 0.5 mA. Muscle force was further manipulated by selective release of blocking currents (600 Hz, 1.7 to 0.4 mA) superimposed over regular stimulation (50 Hz, 0.3 to 1.7 mA). Nerve and muscle vitality were histologically confirmed. Long-term, low-intensity conduction capabilities, fine tuning, good tolerance of implanted electrodes, and lack of fatigue suggest that reinnervating pedicles may be successfully used for pacing when clinically indicated.

Animals↗
PubMed1997

Artificial control of glottic adduction for aspiration by orderly recruitment in the canine.

Laryngeal adduction for swallowing chiefly involves contraction of the thyroarytenoid and lateral cricoarytenoid muscles to seal the glottic chink. Vocal cord elongation supplements closure through cricoarytenoid activation. Relaxation of the posterior cricoarytenoid muscle is also involved in the swallowing process. Recent interest has focused on stimulating the laryngeal nerves to protect the lower airway from conditions where normal muscular coordination may be disrupted (e.g., in aspiration following stroke). Unfortunately, electrical stimulation results in a generalized contraction of all the dependent intrinsic laryngeal muscles because the larger, more excitable axons fire before their smaller counterparts can be activated. In the physiological state, however, the smaller fibers are recruited first. The current study focuses on electronic manipulation of force in the glottic muscles involved in deglutition. We used a stimulator that could selectively activate the intrinsic laryngeal muscles based on their specific motor unit architectures. In 5 dogs, the circuit recruited the axons in the recurrent and superior laryngeal nerves from small to large. The muscles were identified according to the differential recruitment rates of their compound muscle action potentials as they appeared on the graph. The smaller axons in the thyroarytenoid recruited faster than the large ones found in the lateral cricoarytenoid muscles, with intermediate figures observed with the cricothyroid. The posterior cricoarytenoid presented with the slowest recruitment rates, as expected from this muscle's highest contingent of larger motor units. Latencies between the onsets of stimulations and muscle saturations also appeared stable. This approach to manipulating glottic force saves energy because it allows stimulating the adductory muscles with minimal interference from their abductor antagonist.

Action Potentials↗
PubMed1996

Contraction patterns of intrinsic laryngeal muscles induced by orderly recruitment in the canine.

The specific performance of intrinsic laryngeal muscles has been difficult to evaluate, especially in living subjects. To reproduce natural contractions, we artificially induced orderly recruitment of their innervating axons according to the size principle. In 5 dogs, both recurrent laryngeal nerves (RLNs) were stimulated with 50 through 10 Hz, 300 to 1000 microA currents while 600 Hz, 1000 to 0 microA decreasing blocking currents were administered. Surface electromyography electrodes placed on the thyroarytenoid, posterior cricoarytenoid, and lateral cricoarytenoid muscles were used to determine the amplitudes (in mA) of compound muscle action potentials. There was a highly statistically significant difference (P<.004) between the thyroarytenoideus which had the fastest rate of recruitment (8.38%), and posterior cricoarytenoideus, which had the slowest (4.81%). There was an intermediate recruitment rate (6.72%) of the lateral cricoarytenoideus, a divergence attributed to a more equal distribution in fast and slow types of myofibers and a smaller sample. We submit that RLN axons can be recruited in an orderly manner according to their sizes and that the rates are unique to the muscle classes they innervate. The parameters defining these contraction patterns may offer key information for laryngeal pacing.

Animals↗
PubMed1995

Electronic integration of glottic closure and circopharyngeal relaxation for the control of aspiration: a canine study.

Aspiration can result from muscular weakness or paralysis of laryngopharyngeal muscles after lower motor neuron disorders (e.g., stroke) or unchecked gastroesophageal reflux. We submit that rehabilitation of the finely tuned swallowing mechanism should provide at least restoration of the normal dynamic relationships between glottic closure and cricopharyngeal relaxation. In three dogs under general endotracheal anesthesia, the recurrent laryngeal nerves and the pharyngeal musculature were exposed through a midline cervical incision. A tracheotomy was performed to allow unhindered laryngoscopic exposure of the vocal cords. A no. 9 endotracheal tube passed through the upper esophageal sphincter was used as a pressure transducer by saline inflation of its cuff and linked to an oscilloscope. The cricopharyngeus was placed under baseline tension with pulse trains administered by an intramuscular needle with a circuit previously used for agonist/antagonist coupling of reinnervated facial musculature. A second output channel was linked to the contralateral recurrent laryngeal nerve by a bipolar electrode. As the pulse width of the current to the recurrent laryngeal nerve increased, that to the cricopharyngeus was reciprocally decreased, producing snug glottic closure and synchronous cricopharyngeal relaxation. Results were documented on videotape. These findings were highly reproducible. We believe that the novel approach proposed in the current model offers an attractive solution to long-term aspiration problems resulting from an imbalance between vocal cord and cricopharyngeal activities.

Animals↗
PubMed1994

Artificial reflex arc: a potential solution for chronic aspiration. III: Stimulation of implanted cervical skin as a functional graft triggering glottic closure in the canine.

Stroke often impairs the ability of the vocal cords to close during deglutition, resulting in aspiration. The current study is a further advance on the application of the concept of an artificial reflex arc during swallowing. The second and third cervical branches were bilaterally isolated in four dogs and baseline sensory nerve traffic was detected via tripolar perineural electrodes. Cervical skin pressure-induced suprathreshold signals were used to trigger vocal cord contraction via bipolar electrodes passed around the recurrent laryngeal nerves. Skin subtended by the cervical nerves was implanted over the lateral aspect of the pyriform sinuses for 1 week. After reexploration, glottic closure was verified on videotape as surges in sensory nerve traffic were induced by mechanical stimulation of the pharynx. The possibility of artifactual stimulation was ruled out by lack of electrode motion during pharyngeal stimulation, spontaneous firing in the sensory nerve during light anesthesia, and sensory frequency differing from ambient 60-Hz noise. This article introduces the concept of autogenous functional graft as a basis for afferent information in electronic systems for dynamic rehabilitation of swallowing disorders.

Animals↗
PubMed1993

Dynamic control of the larynx and future perspectives in the management of deglutitive aspiration.

The approach to deglutitive aspiration presented in this article is original. It permitted restoring the dynamic nature of the swallowing process in immobile largynges, a situation found when function has been abolished through central neurological deficit. The necessity, in the author's view, for a miniaturized electronic system bypassing the diseased centers able to produce tight glottic closure in a canine model during pharyngeal stimulation is emphasized. There is hope that we may ultimately move towards human implantation if the proposed electronics will be well tolerated over time.

Deglutition Disorders↗
PubMed1993

Electronic control of laryngeal spasm. II. Selective blockage of glottic adduction by a closed-loop circuit in the canine.

This work is the continuation of an earlier pilot study in which specially designed electrodes were used to block their own induced action potentials to restrain spasticity. In the current series of experiments, strap muscle and thyroarytenoid contraction (glottic closure) elicited by supramaximal ansa hypoglossi (N = 6) and recurrent laryngeal nerve (N = 4) stimulation (30 to 50 Hz, 0.1 to 6 mA, 0.1 to 1 msec), respectively, allowed afferent information via intramuscular sonomicrometer crystals to trigger a circuit that, in turn, stimulated blocking electrodes passed around the nerves downstream. Simultaneous videorecording of strap and vocal cord motion during direct laryngoscopy with their corresponding excursion tracings demonstrated near-total suppression of contractions within given stimulation "windows." These encouraging results may eventually permit selective restraint of erratic contractions involving laryngeal and other cervical musculatures in the human.

Action Potentials↗
PubMed1993

Intramuscular hemangiomas of the masseter and sternomastoid muscles.

Two cases of hemangiomas involving the masseter and sternomastoid muscle are added to the English literature. Our limited experience with these cases confirms that preoperative diagnosis and planning can be difficult. Recurrences of tumors are related to incomplete excisions although their further treatments in the final analysis depend on the adjacent structures affected. Careful individualization of treatment is therefore a necessity. Embolization is not sufficient therapy if not followed by surgery.

Adult↗
PubMed1991

Dynamic rehabilitation of the paralyzed face: III: Balanced coupling of oral and ocular musculature from the intact side in the canine.

We have recently demonstrated the feasibility of artificial agonist/antagonist coupling between intact facial and reinnervated strap muscles in the rabbit. The present study broadens this principle to involve bi-level cross-facial innervation. After severing the facial innervation unilaterally in four dogs, a nerve pedicle from a cervical motor nerve was implanted into the orbicularis oris and from the deep temporal nerve into the orbicularis oculi. After neurotization (5.6 months), the pedicles were electrically stimulated to verify muscular response. Graded contraction on the intact side was induced by stimulating the ipsilateral facial nerve with currents of various pulse widths. The resulting compression of a strain gauge on the intact face triggered a two-channel, opto-isolated, pulse width-modulated stimulator to produce agonistic graded contraction at one level of the reinnervated side (e.g., oral) and reciprocal relaxation in its reinnervated counterpart (e.g., ocular). The sophistication of the present model--as compared to the original pilot study--brings us one step closer to dynamic human facial rehabilitation.

Animals↗
PubMed1990

Correlation between histology and nerve excitability after reinnervation of paralyzed strap muscles in the rabbit.

We have recently shown that the mean muscle chronaxie for nerve pedicle implanted into denervated rabbit strap muscle is comparable to that of normal nerve. This study correlates excitability with histologic characteristics of muscles reinnervated via nerve-muscle pedicles (NMP) and direct nerve implants (DNI). Strength duration curves were measured in 13 rabbits 3.5 to 5 months after reinnervation by NMP (n = 6) and DNI (n = 7). Following this, control (n = 5) and reinnervated straps were harvested immediately before the animals were killed and frozen in liquid nitrogen. The material was submitted for hematoxylin-eosin stains as well as trichrome stains for general morphology, myofibrillar ATPase and NADH for fiber typing, and cholinesterase for determination of denervated fibers. In all animals with low chronaxie, expected type grouping from reinnervation was noted (n = 10). By contrast, the three animals in which chronaxie was abnormally elevated demonstrated fibrosis, inflammation, and absence of or poor type grouping. This suggests that type grouping is necessary for excitability after reinnervation of paralyzed striated muscles.

Animals↗