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I Sanders

Publications and source records attributed to I Sanders.

At least 37 records · Page 2Linked to original sources
PubMed1995

A microsatellite marker for studying the ecology and diversity of fungal endophytes (Epichloë spp.) in grasses.

Randomly amplified polymorphic DNA fingerprinting, which is based on PCR with arbitrary 10-nucleotide primers, were used to analyze genetic diversity among isolates of the endophytic ascomycete Epichloë typhina, which were collected at a single field site from a population of one of its hosts, the grass Bromus erectus. One of the polymorphic randomly amplified polymorphic DNA PCR products occurred in all isolates as single bands with different but closely related sizes. Two of the size variants of this product were cloned and sequenced, and they were found to represent the same DNA sequence, except for a stretch of tandem repeats of the trinucleotide AAG.TTC, which differed in size, consisting of 8 and 18 repeats, respectively. Tandem repeats of this type are called microsatellites. Oligonucleotides were synthesized corresponding to portions of the sequence flanking the microsatellite and were used for PCR amplification of the loci from the genomic DNAs of different Epichloë isolates. A single PCR product was found for most isolates, indicating that the sequence represented a single genetic locus. Five alleles that could clearly be distinguished in size were found in a population of 91 field isolates. PCR with (AAC)8 and (AAG)8 as primers yielded a number of amplified bands from genomic DNA of Epichloë isolates, indicating that these types of microsatellites occur frequently in the genome of this fungus. A survey of all fungal DNA sequences currently deposited in the DNA sequence databases of EMBL and GenBank revealed that microsatellites of different repeating units are widespread in fungi.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1995

Rhinorrhea is decreased in dogs after nasal application of botulinum toxin.

At this time no effective long-term therapy exists for the excessive secretion of vasomotor rhinitis. Because rhinorrhea is under parasympathetic control, it was theorized that botulinum toxin--a powerful and long-acting cholinergic blocker that has been successful in the treatment of dystonia--might be useful in blocking the cholinergic control of rhinorrhea. Four male mongrel dogs were studied. Fifty units of type A botulinum toxin was soaked into sterile gauze, which was then packed into the left nasal cavity of each dog for 1 hour. Saline-soaked gauze was similarly introduced into the right nasal cavity to serve as control. Six days later, rhinorrhea was produced by inserting a bipolar needle electrode into the sphenopalatine ganglion and electrically stimulating for 10 minutes (6 mA, 50 Hz). Nasal secretions were collected with a suction catheter placed in the nasal vestibule. Three of four dogs exposed to the toxin showed a 41% average decrease in rhinorrhea (specifically 53%, 41%, and 30%). One dog showed a 10% increase in secretion after exposure to the toxin. We conclude that topically applied botulinum toxin reduced neurally evoked rhinorrhea by an average of 41%. Because some secretion is mediated by noncholinergic neurotransmitters such as vasoactive intestinal peptide, topical application of an anticholinergic substance has limitations. However, because all the nasal parasympathetic nerves appear to originate from cholinergic synapses in the sphenopalatine ganglion, direct injections of toxin into this ganglion may possibly allow complete blockade of all cholinergically mediated rhinorrhea.

Administration, Intranasal↗
PubMed1994

The human communicating nerve. An extension of the external superior laryngeal nerve that innervates the vocal cord.

OBJECTIVE: A second source of motor innervation for the thyroarytenoid (TA) muscle, other than the recurrent laryngeal nerve, has been suggested by clinical and experimental observations. Early anatomists noted what appeared to be small nerves connecting the cricothyroid and TA muscles; however, these observations were disputed by later anatomists and subsequently forgotten. METHOD: In this study, we processed 27 human hemilarynges with Sihler's stain, a technique that clears soft tissue and counterstains nerve. In addition, four communicating nerves (CNs) were frozen sectioned and stained for acetylcholinesterase, a marker for motor neurons. RESULTS: In 12 (44%) of the 27 specimens, a neural connection was found that exited the medial surface of the cricothyroid muscle and then entered into the lateral surface of the TA muscle. In general, this CN was composed of two parts: an intramuscular branch usually combined with the recurrent laryngeal nerve or terminated within the TA muscle directly and an extramuscular branch that passed through the TA muscle and terminated in the subglottic mucosa and around the cricoarytenoid joint. All four CNs tested positive for acetylcholinesterase. Specifically, the CNs contained an average of 2510 myelinated axons, of which 785 (31%) were motor neurons. CONCLUSION: The results suggest that when the CN is present, it supplies a second source of motor innervation to the TA muscle and extensive sensory innervation to the subglottic area and cricoarytenoid joint. In addition, the CN may be the nerve of the fifth branchial arch, a structure that has never been identified (to our knowledge).

Acetylcholinesterase↗
PubMed1994

The intramuscular innervation of the human interarytenoid muscle.

The nerve supply of the human interarytenoid (IA) muscle has been controversial for more than a century. In this study the contribution of the recurrent and superior laryngeal nerves to the IA was investigated in 10 adult human larynges. The larynges were obtained from autopsies and processed with the modified Sihler's technique which clears soft tissue while staining nerve. The IA muscles were dissected off the specimens and transilluminated to demonstrate their nerve supply. The results demonstrated that all 10 IA muscles were bilaterally innervated by both recurrent laryngeal nerves (RLNs) as well as branches of both superior laryngeal nerves (SLNs). These nerves combined within the IA muscles to form a dense anastomotic plexus which was highly variable between specimens. The exact nature of the internal SLN neurons, whether motor or sensory, their innervation targets, or their function, were not discernible. Additional anatomic findings were the presence of large neural communications directly between the SLN and RLN, and smaller neural connections from side to side. All of these results disagree with currently accepted descriptions of laryngeal neuroanatomy.

Adult↗
PubMed1994

Arytenoid motion evoked by regional electrical stimulation of the canine posterior cricoarytenoid muscle.

Anatomical studies have demonstrated that the posterior cricoarytenoid muscle in the dog is composed of three bellies. These bellies are termed vertical, oblique, and horizontal on the basis of their orientation. The purpose of this study was to show whether each of these bellies can move the vocal fold in different ways. Ten anesthetized dogs underwent laryngectomies while paralyzed with curare. The posterior cricoarytenoid muscles were then exposed by dissecting the overlying esophageal mucosa. Electrical stimulation was applied to each belly, and the motion of the arytenoid cartilage was measured. Because the oblique belly overlies the vertical belly, they were usually stimulated together. It was found that the vertical and oblique bellies rock the arytenoid backwards while sliding it laterally, thus causing a maximal dilation of the airway. The horizontal belly caused a swiveling motion of the arytenoid. It is proposed that the vertical and oblique bellies normally cause vocal fold abduction during respiration, while the horizontal belly primarily is used to adjust finely the position of the vocal process during phonation. Because the human posterior cricoarytenoid is also composed of separate bellies it, too, may have distinct functions.

Animals↗
PubMed1994

The innervation of the human posterior cricoarytenoid muscle: evidence for at least two neuromuscular compartments.

Recent work has demonstrated that the dog posterior cricoarytenoid (PCA) muscle is composed of three neuromuscular compartments: a vertical, an oblique, and a horizontal. In this study, the human PCA muscle was examined for evidence of neural compartments. Fifteen human PCA muscles were processed by Sihler's stain, which renders the muscle translucent while counterstaining the nerve supply. The results clearly show that in all specimens the nerve supply of the human PCA muscle is separated into at least two main branches: one supplies the horizontal compartment and a second further subdivides to innervate both the vertical and oblique compartments. In 10 of the specimens, these nerve branches arose as separate branches from the recurrent laryngeal nerve. In all specimens, the nerve branch to the horizontal compartment was either combined or connected with the nerve branch to the interarytenoid muscle. The results suggest that the different compartments of the PCA muscle have distinct functions. In addition, the strong connections with the interarytenoid nerve complicate reinnervation procedures to reanimate a paralyzed or transplanted larynx.

Aged↗
PubMed1993

The innervation of the human larynx.

OBJECTIVE: To investigate the gross anatomy of the recurrent and superior laryngeal nerves (RLNs and SLNs) in 10 human larynges. METHODS: Whole larynges were processed to clear all soft tissue while leaving nerves stained. Then the main laryngeal nerves and the muscles they innervate were dissected and analyzed. RESULTS: It was found that in all larynges the RLNs and SLNs are connected by nerve branches other than Galen's anastomosis. The most consistent connection is in the interarytenoid muscle, where RLNs and internal SLNs combine in a neural plexus. A less consistent connection occurs in the piriform fossa, where a continuation of the external SLN passes from the cricothyroid muscle to the thyroarytenoid muscle. CONCLUSION: Based on these findings it is proposed that there are significant neural connections between the RLN and SLN systems. In addition, limited cross-innervation is seen from side to side in the area of the interarytenoid muscle. Other findings concern the innervation patterns within the laryngeal muscles. The posterior cricoarytenoid, cricothyroid, and thyroarytenoid muscles all appear to be composed of separate bellies based on the configuration of their nerve supply. Most notable is the region of the thyroarytenoid muscle at the vocal cord margin that is innervated by a nerve plexus of extreme complexity. The details of the innervation patterns suggest functional differences within and between laryngeal muscles.

Acetates↗
PubMed1993

A technique for displaying the entire nerve branching pattern of a whole muscle: results in 10 canine posterior cricoarytenoid muscles.

There is anatomical and histological evidence for three functionally distinct muscle bellies in the canine posterior cricoarytenoid (PCA) muscle. This study attempted to define the exact nerve branching pattern to each muscle belly in 10 dogs using a modification of Sihler's neural staining technique. The results are presented here as photographs and schematic nerve maps which illustrate the following points. 1. the final terminal branches within the PCA do correspond to the three bellies of the PCA; 2. the initial nerve branch to the PCA is usually composed of multiple fascicles which rearrange before their final branching to the three bellies; 3. there is tremendous variability of the nerve branching patterns including bilateral asymmetry within the same animal; 4. the terminal branching within each belly can be surprisingly complex and contain multiple anastomoses; 5. the fast- and slow-twitch bellies of the PCA have different terminal branching patterns. These results support the functional subdivision of the canine PCA into three distinct neuromuscular compartments. This microanatomical technique appears useful for studying the basic neuromuscular organization of laryngeal muscles and their developmental and pathological changes.

Animals↗
PubMed1993

The three bellies of the canine posterior cricoarytenoid muscle: implications for understanding laryngeal function.

The posterior cricoarytenoid (PCA) muscle is known to be active during phonation and respiration. The presence of muscle compartments (bellies) that might subserve these functions was investigated in the canine PCA by anatomical dissection and muscle fiber histochemistry. Five PCA muscles were microdissected and the origins and insertions of all muscle bundles were recorded. An additional six PCA muscles were frozen, sectioned, and stained for adenosine triphosphatase (ATPase) activity. The total number of fast- and slow-twitch fibers were counted and their proportion was determined for each region of the muscle. The PCA muscle was found to contain three distinct neuromuscular compartments. The vertical compartment is oriented at 24 degrees from true vertical, inserts on the lateral aspect of the muscular process of the arytenoid, and is composed of 65% type 2 (fast) muscle fibers. The oblique is oriented at 44 degrees from vertical, inserts on the top of the muscular process of the arytenoid, and is composed of 77% type 2 muscle fibers. The horizontal is oriented at 63 degrees from vertical, inserts on the medial aspect of the muscular process of the arytenoid, and is composed of 59% type 2 muscle fibers. The cricoarytenoid joint is capable of three arcs of motion and the physical arrangement of each compartment appears to correspond to each of these motions. Moreover, the histochemical profiles show that the activity of the three bellies is quite different. These results suggest that the different compartments of the PCA perform distinctive motions during phonation and inspiration.

Adenosine Triphosphatases↗
PubMed1993

Vocal cord paralysis: clinical and electrophysiologic features.

Vocal cord paralysis may occur in isolation or as part of a constellation of findings in neurological disease. We investigated the pathophysiology of these disorders with laryngeal electromyography (LEMG). We studied 44 patients with idiopathic vocal cord paralysis, confirmed by laryngoscopy. The major LEMG finding, present in 29 vocal cords, was evidence of active or chronic denervation in the thyroarytenoid (TA), indicating recurrent laryngeal neuropathy. Denervation of the cricothyroid (CT) in 5 patients indicated superior laryngeal neuropathy. TA and CT involvement in 1 patient indicated proximal laryngeal or vagus nerve damage. LEMG was performed in 48 patients with other laryngeal disorders. LEMG proved to be a safe and effective procedure in the diagnosis of laryngeal neuropathy as distinguished from supranuclear and mechanical disorders of the larynx.

Electromyography↗
PubMed1993

Quantifying how location and dose of botulinum toxin injections affect muscle paralysis.

Despite the widespread use of botulinum toxin to treat muscle dystonias, no method exists to quantify muscle paralysis in either human or nonhuman models. In this study we examined how the location, dose, and volume of botulinum injection affects paralysis in the rat tibialis anterior muscle. Paralysis was quantified by electrically stimulating the nerve to the tibialis anterior and then staining sections of the muscle for glycogen. The areas of glycogen-containing fibers represented regions of botulinum action. The results showed that the most important injection technique is to inject botulinum directly into the motor endplate region of a muscle. Injections only 0.5 cm from the motor endplate resulted in a 50% decrease in paralysis. Increases in dose increased paralysis, however, some of that increase was simply due to the increased volume of injection. Thus, delivering toxin in small volumes near the MEP band of a muscle should produce the most effective paralysis.

Animals↗
PubMed1993

The intramuscular nerve supply of the human lateral cricoarytenoid muscle.

The lateral cricoarytenoid (LCA) muscle is one of the adductors of the vocal cords; however, some investigators believe that the lateral edge of the muscle may be involved in abduction. The possibility of functionally distinct compartments within the LCA was investigated by observing the pattern of the intramuscular nerve supply. This technique has previously clearly demonstrated neural compartments in the posterior cricoarytenoid, thyroarytenoid and cricothyroid muscles. Five adult human larynges were processed by the Sihler's stain which clears all soft tissue while counterstaining the nerves. The results of our study showed that the innervation pattern of the human LCA muscle is composed of a homogenous nerve plexus localized to the middle region of the muscle. This pattern correlates with the location of motor endplates described by prior investigators. The consistent neural pattern suggests that the LCA is composed of a single neuromuscular compartment.

Adult↗
PubMed1992

A technique for demonstrating the nerve supply of whole larynges.

At present there is a large gap in our understanding of the exact distribution of sensory and motor nerves within the larynx. Gross dissection is only accurate for large-caliber nerves, whereas microscopic sections show only isolated examples of terminal branching. To fill this gap, we modified an old technique called Sihler's stain to process five whole canine larynges. The technique requires eight steps that take approximately 3 months. The result is an entire larynx in which muscle and cartilage are rendered translucent, while nerve is counterstained. Nerve branching can be continuously traced from the large-caliber nerves to the terminal branches. We found that the nerve patterns are surprisingly complex and contain frequent anastomotic networks. This technique is a powerful tool for studying certain neurolaryngological problems.

Animals↗
PubMed1992

Quantitative mapping of the effect of botulinum toxin injections in the thyroarytenoid muscle.

Spasmodic dysphonia has been successfully treated by thyroarytenoid muscle injections of botulinum toxin (Botox) with dosages ranging from 0.625 to 25 U. In some patients, excessive paralysis with resulting breathiness and aspiration have been noted. In order to maximize the efficiency of Botox injections, the histologic effects of various Botox dosages were examined in the dog. Nine canine thyroarytenoid muscles were injected with 0.5 to 12.5 U of Botox. After 24 hours, the recurrent laryngeal nerve to the injected muscle was electrically stimulated in order to deplete the glycogen within the muscle fibers. Frozen sections of this muscle were then stained for glycogen. Those fibers that retained their glycogen were presumed paralyzed by the Botox injection. The extent of paralysis was found to be dose-related from 1.0 to 7.5 U. At 10 U and above the muscle was completely paralyzed. Spread of the toxin to the lateral cricoarytenoid muscle was seen at doses as low as 1.0 U. Clearly, doses less than 10 U appear sufficient for clinical paralysis.

Animals↗
PubMed1992

Continuous positive airway pressure as a promoter of laryngospasm during halothane anesthesia.

Twenty mongrel dogs were anesthetized with halothane 2.0%, 1.25%, 0.94%, and 0.63% in oxygen. Thyroarytenoid (TA) and posterior cricoarytenoid (PCA) electromyography (EMG) tracings were recorded with the animal at rest, following mechanical irritation of the glottis, and during 20 mm Hg continuous positive airway pressure (CPAP) following either airway occlusion or hyperventilation. Adductor laryngospasm was defined as continuous tonic TA EMG activity, silent PCA EMG, and vocal cord adduction. Abductor laryngospasm was defined as continuous tonic PCA EMG activity, silent TA EMG, and vocal cord abduction. Combined laryngospasm was defined as continuous tonic PCA and TA EMG activity, with variable vocal cord position. The incidence of adductor laryngospasm following mechanical irritation was 30% to 50%. The combined incidence of laryngospasm during application of CPAP following airway occlusion or hyperventilation was 25% to 50%, and differed from the incidence of irritation-induced adductor laryngospasm by 5% or less at the same anesthetic level. Continuous positive airway pressure appears to be a stimulant of laryngeal muscle spasm comparable to mechanical irritation of the glottis.

Airway Obstruction↗
PubMed1992

The three bellies of the canine cricothyroid muscle.

The cricothyroid muscle is capable of multiple functions, including vocal cord elongation and adduction. In addition, the cricothyroid can lengthen the glottis as well as provide posture to the cricothyroid joint. The purpose of the present study is to demonstrate that the many functional capabilities of the cricothyroid are a reflection of the existence of separate bellies within the muscle. Microdissection revealed three distinct muscle bellies within the cricothyroid: rectus, oblique, and horizontal. These differ in fiber orientation (rectus 79 degrees, oblique 48 degrees, horizontal 7 degrees) and are separated by fascial planes. Histochemistry showed that these three bellies are composed of different percentages of slow twitch fibers (rectus 31.3%, oblique 43.3%, horizontal 39.6%). Finally, electromyography demonstrated differences in the electrical activity patterns of the three bellies. It is concluded that the cricothyroid muscle is composed of three distinct muscle bellies that probably play separate roles in the complex function of this muscle.

Animals↗
PubMed1992

The intramuscular nerve supply of the posterior cricoarytenoid muscle of the dog.

The paired posterior cricoarytenoid (PCA) muscle has three separate muscle bellies that differ in muscle fiber type (percentage of fast vs. slow twitch) and electromyelographic activity, and, in addition, produce different movements of the arytenoids when stimulated. An investigation of the innervation of the muscle was undertaken to demonstrate the existence of separate functional units. The intramuscular nerve supply of the PCA from five sacrificed dogs were microdissected. The intramuscular nerves of three additional dogs were removed and stained for acetylcholinesterase, which differentiates axons bound for fast- and slow-twitch muscle, and sensory end organs. Three separate fascicles are described entering the PCA muscle from a single branch of the recurrent laryngeal nerve. The three fascicles differ in axon type composition and in sensory, autonomic, and motor percentages, with the ratio of fast twitch to slow twitch varying from 0.78 to 1.5 to 1.7 (P less than .05). This variation supports separate functional capabilities for the three muscle bellies of the PCA.

Animals↗