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PubMedDate not supplied

Epidemiological and clinical features of group A Streptococcus pharyngitis in children.

In order to understand the prevalence of childhood streptococcal pharyngitis, isolation of group A Streptococcus (GAS) was attempted from throat swabs of pharyngitis patients. Children aged between 1 and 15 years presenting to the outpatient department with pharyngeal erythema were prospectively enrolled in the study. Demographic data and presenting symptoms and signs for each patient were recorded and a throat swab was taken. Of 1175 throat cultures obtained, GAS was isolated in 252 cases (21.4%). Of these, 142 (56.3%) were boys and 110 (43.7%) girls. A higher proportion of boys was found with GAS pharyngitis (1.29: 1). The mean age of GAS culture-positive patients was 7.8 +/- 2.3 years old. Patients aged between 6 and 11 years were more prevalent in GAS pharyngitis. Ninety (35.7%) of our GAS pharyngitis patients occurred between March and May. A second smaller peak occurred between October and December. The following factors showed independent positive correlation with GAS infection: sore throat (p < 0.001), no coryza (p = 0.011), tonsillar swelling (p < 0.001), anterior cervical adenopathy (p = 0.029) and scarlatiniform rash (p < 0.001). However, GAS was found in less than half of the patients who had these clinical manifestations. In conclusion, pharyngeal infection with GAS in children is not uncommon. The prevalence of GAS pharyngitis is related to patient gender, age, and month of the year. Diagnosis of GAS pharyngitis based on clinical features alone is unreliable.

Child↗

PubMed1989

Pharyngeal gonorrhea screening in adolescents: is it necessary?

A prospective study was performed to examine the prevalence of pharyngeal gonorrhea in two urban female adolescent populations and to compare pharyngeal infection with a history of orogenital activity and concurrent genital gonorrhea. Group I was drawn from a children's hospital adolescent clinic and group II was drawn from a public health clinic for sexually transmitted diseases. None of the 240 adolescents in group I had a pharyngeal culture positive for Neisseria gonorrhoeae compared with 3.4% in group II. Only 2.5% of group I had genital gonorrhea, but 33% of group II had positive genital cultures. In only two of the 20 patients with pharyngeal gonococcal infection was the pharynx the only infected site. The addition of routine pharyngeal culturing for gonorrhea yielded only 1% additional gonorrhea cases. There was a significant relationship between concurrent genital and pharyngeal gonorrhea. These findings indicate that routine screening for pharyngeal gonorrhea is not productive in some adolescent populations. A more economic approach would be to use gonorrhea treatment that is effective against both genital and pharyngeal gonorrhea or to obtain pharyngeal cultures in those adolescents returning for test-of-cure cultures after antibiotic treatment for genital gonorrhea.

Adolescent↗

PubMed1986

Contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the swallowing process in dogs.

The separate contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the innervation of the pharyngeal muscles were studied first in 10 canine cadavers by dissection of the pharyngeal plexus and the pharyngeal muscles. In 10 other dogs, the parent trunks and 1st division of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve were electrically stimulated. The evoked stimulation potentials were recorded from the stylopharyngeal, hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles. One of the parent trunks was then transected, and the effects on the swallowing process were observed clinically and by contrast videofluorography. Denervation potentials resulting from nerve transection were recorded in the soft palate, the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles. The pharyngeal plexus was composed of branches originating from the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve. In most dogs, the pharyngeal muscles and the soft palate were innervated ipsilaterally by both nerves. The swallowing process was more severely disturbed after bilateral transection of the pharyngeal branch of the vagus nerve than after bilateral transection of the glossopharyngeal nerve.

Animals↗

PubMed2002

Deficits in the posterior pharyngeal endoderm in the absence of retinoids.

Recent studies have shown that the pharyngeal endoderm plays a critically important role in directing the development of the pharyngeal region of the vertebrate embryo. We have, however, had few insights into how the pharyngeal endoderm itself is patterned. Recently, several studies have suggested that retinoic acid is required for the development of the pharyngeal endoderm. To study this proposal in greater depth, we have examined the development of the pharyngeal endoderm in the absence of retinoid signalling, by using the vitamin A- deficient (VAD) quail model system. We find in early stages that, in the absence of retinoids, this territory extends further caudally than normal. Furthermore, as development proceeds, we find that the first pouch invariably forms, that the second pouch is abnormal, and that the third and fourth pharyngeal pouches never form. We do find, however, that dorsoventral patterning of the pharyngeal endoderm is unaffected. Finally, we have examined the expression patterns of RALDH2 before and during early development of the pharyngeal pouches. We find that this enzyme is expressed adjacent to the pharyngeal endoderm in tissues around the regressing anterior intestinal portal and that from stage 12 onward its anterior limit of expression lies at the level of the second pouch. This finding helps explain why the first pouch always forms in the absence of retinoids, and why defects are seen starting with the second and most evidently in the caudal pouches.

Aldehyde Oxidoreductases↗

PubMed2006

Retinoic acid is required for endodermal pouch morphogenesis and not for pharyngeal endoderm specification.

Because tissues from all three germ layers contribute to the pharyngeal arches, it is not surprising that all major signaling pathways are involved in their development. We focus on the role of retinoic acid (RA) signaling because it has been recognized for quite some time that alterations in this pathway lead to craniofacial malformations. Several studies exist that describe phenotypes observed upon RA perturbations in pharyngeal arch development; however, these studies did not address whether RA plays multiple roles at distinct time points during development. Here, we report the resulting phenotypes in the hindbrain, the neural crest-derived tissues, and the pharyngeal endoderm when RA synthesis is disrupted during zebrafish gastrulation and pharyngeal arch morphogenesis. Our results demonstrate that RA is required for the post-gastrulation morphogenesis and segmentation of endodermal pouches, and that loss of RA does not affect the length of the pharyngeal ectoderm or medial endoderm along the anterior-posterior axis. We also provide evidence that RA is not required for the specification of pharyngeal pouch endoderm and that the pharyngeal endoderm consists of at least two different cell populations, of which the pouch endoderm is sensitive to RA and the more medial pharyngeal endoderm is not. These results demonstrate that the developmental processes underlying pharyngeal arch defects differ depending on when RA signaling is disturbed during development.

Animals↗

PubMed2004

Oropharyngeal scintigraphy: a reliable technique for the quantitative evaluation of oral-pharyngeal swallowing.

A valid and reliable technique to quantify the efficiency of the oral-pharyngeal phase of swallowing is needed to measure objectively the severity of dysphagia and longitudinal changes in swallowing in response to intervention. The objective of this study was to develop and validate a scintigraphic technique to quantify the efficiency of bolus clearance during the oral-pharyngeal swallow and assess its diagnostic accuracy. To accomplish this, postswallow oral and pharyngeal counts of residual for technetium-labeled 5- and 10-ml water boluses and regional transit times were measured in 3 separate healthy control groups and in a group of patients with proven oral-pharyngeal dysphagia. Repeat measures were obtained in one group of aged (> 55yr) controls to establish test-retest reliability. Scintigraphic transit measures were validated by comparison with radiographic temporal measures. Scintigraphic measures in those with proven dysphagia were compared with radiographic classification of oral vs. pharyngeal dysfunction to establish their diagnostic accuracy. We found that oral ( p = 0.04), but not pharyngeal, isotope clearance is swallowed bolus-dependently. Scintigraphic transit times do not differ from times derived radiographically. All scintigraphic measures have extremely good test-retest reliability. The mean difference between test and retest for oral residual was -1% (95% CI -3%-1%) and for pharyngeal residual it was -2% (95% CI -5%-1%). Scintigraphic transit times have very poor diagnostic accuracy for regional dysfunction. Abnormal oral and pharyngeal residuals have positive predictive values of 100% and 92%, respectively, for regional dysfunction. We conclude that oral-pharyngeal scintigraphic clearance is highly reliable, bolus volume-dependent, and has a high predictive value for regional dysfunction. It may prove useful in assessment of dysphagia severity and longitudinal change.

Adolescent↗

PubMed2006

Can a fluoroscopic estimation of pharyngeal constriction predict aspiration?

BACKGROUND: The pharyngeal constriction ratio (PCR) is a ratio of pharyngeal area measured in lateral fluoroscopic view at the point of maximum pharyngeal constriction during the swallow to the pharyngeal area measured with the bolus held in the oral cavity. We hypothesize that the PCR may represent a surrogate measure of pharyngeal strength. OBJECTIVE: To investigate the relationship between the PCR and aspiration. STUDY DESIGN AND SETTING: Data from a computerized clinical database of individuals undergoing a videofluoroscopic swallow evaluation at a tertiary academic swallowing center was acquired. RESULTS: Two hundred sixty videofluoroscopic studies were abstracted. The mean PCR was 0.32 (+/- 0.02) for individuals who aspirated and 0.20 (+/- 0.02) for individuals who did not (P < 0.001). In a multiple logistic regression analysis, the PCR was significantly associated with the prevalence of aspiration (P < 0.01). Individuals with a PCR greater than 0.25 were 3 times more likely to aspirate (95% CI = 1.7, 5.1). CONCLUSIONS: The pharyngeal constriction ratio is associated with the presence of aspiration on fluoroscopy. Before the PCR can be used as a surrogate measure of pharyngeal constriction, correlation with pharyngeal manometry will be necessary. SIGNIFICANCE: The pharyngeal constriction ratio is associated with the presence of aspiration on fluoroscopy. EBM RATING: B-3b.

Aged↗

PubMed2001

Pharyngeal pH measurements in patients with respiratory symptoms before and during proton pump inhibitor therapy.

BACKGROUND: Pharyngeal pH monitoring is a diagnostic tool used to identify Gastroesophageal reflux disease (GERD) as an etiology of respiratory symptoms. We performed pharyngeal pH monitoring on 14 patients with respiratory symptoms thought to be induced by GERD. METHODS: Symptoms and pH monitoring (esophageal and pharyngeal) were assessed prior to and 3 months after the initiation of double-dose proton pump inhibitor therapy. RESULTS: Symptoms included cough, hoarseness, and throat clearing. Ten patients had at least one episode of pharyngeal reflux (PR+) and 4 patients had no pharyngeal reflux (PR-). Pharyngeal reflux episodes in PR+ patients decreased from 3.5 to 0.9 (P <0.05) per day with 8 of 10 (80%) patients having elimination or reduction of such episodes. Eight of 9 PR+ patients (89%) with suppressed pharyngeal reflux on medical therapy had resolution of respiratory symptoms. Three of 4 PR- patients (75%) had persistent symptoms on medical therapy. CONCLUSIONS: Proton pump inhibitor therapy improves clinical symptoms and decreases pharyngeal reflux episodes in patients with respiratory symptoms related to GERD. Direct measurement of pharyngeal pH is helpful in the identification of patients likely to respond to antireflux therapy.

Anti-Ulcer Agents↗

PubMed2002

The heterogeneity of endemic community pediatric group a streptococcal pharyngeal isolates and their relationship to invasive isolates.

By use of molecular techniques, the genetic heterogeneity of 63 community pediatric pharyngeal group A streptococcal (GAS) isolates circulating within a 3-week period were compared with 17 contemporaneous invasive pediatric isolates. Pharyngitis isolates represented 16 pulsed-field gel electrophoresis (PFGE) patterns with 12 emm serotypes, and invasive isolates represented 10 PFGE patterns with 9 emm serotypes. One-fourth of the pharyngeal isolates (16/63) were identical to at least 1 invasive isolate; conversely, 10 (59%) of 17 invasive isolates were identical to at least 1 pharyngeal strain. sic allele analysis of emm1 strains demonstrated additional heterogeneity and overlap. More pharyngeal (71%) than invasive isolates (35%) were positive for both speA and speC (P<.02). Many pharyngitis GAS strains circulate simultaneously. Most invasive pediatric GAS strains are identical to acute pharyngitis strains; thus, childhood pharyngitis is a major reservoir for strains with invasive potential. Pharyngeal isolates were more likely to be speA and speC positive than were the invasive isolates.

Adolescent↗

PubMed2007

Impedance signature of pharyngeal gaseous reflux.

BACKGROUND: Pharyngeal impedance changes induced by various pharyngeal reflux events have not been characterized. OBJECTIVES: To characterize pharyngeal impedance changes induced by participant-perceived belching events. METHODS: We systematically evaluated pharyngeal impedance and pH changes related to 453 belch events in 11 gastroesophageal reflux disease, 10 reflux attributed-laryngitis patients and 16 controls. RESULTS: Of 453 belch events, 362 were analyzable. Of these, 72% occurred within 10 s, 93% within 20 s, 99% within 30 s and 100% within 40 s of the time that participants marked a belch event. In 15% impedance changes in the pharynx preceded, in 12% they were simultaneous and in 73% they occurred after the start of the impedance change in the proximal esophagus. Time interval between the two events ranged between 0.4+/-0.03 and 0.7+/-0.1 s. In all, there were three types of belch-induced impedance changes: (a) impedance increase, (b) impedance decrease and (c) multiphasic. Twenty percent of impedance events associated with belching had less than 50% change from baseline, whereas in 51% changes exceeded or were equal to 50%. Among events with a drop in pharyngeal impedance, only two satisfied the criteria for the liquid reflux event. CONCLUSIONS: Pharyngeal ventilation of gastric gaseous content seems to have a unique impedance signature. During pharyngeal gas reflux events, impedance changes may start before or after proximal esophageal changes. Belching may induce negative pharyngeal changes that do not meet the criteria for liquid reflux. These findings need to be taken into consideration in the analysis of pharyngeal reflux events.

Adult↗

PubMed1999

Topical pharyngeal anesthesia does not improve upper gastrointestinal endoscopy in conscious sedated patients.

OBJECTIVE: We undertook this study to determine whether topical pharyngeal anesthesia with conscious sedation is superior to conscious sedation alone, with respect to procedure performance or tolerance in patients undergoing diagnostic upper gastrointestinal endoscopy. METHODS: Ninety-five patients undergoing diagnostic upper endoscopy with conscious sedation were randomized to receive either topical pharyngeal anesthesia with 2% tetracaine/14% benzocaine spray or no pharyngeal anesthesia. Conscious sedation was achieved in all patients using intravenous midazolam and meperidine. Patients were asked to rate their pretest anxiety, comfort during endoscopy, recollection of the procedure, and willingness to undergo subsequent examinations using a 100-mm visual analog scale. Additionally, they were asked to estimate procedure duration and rate their tolerance for topical pharyngeal anesthesia. All examinations were performed by two endoscopists who were blinded to whether or not patients had received pharyngeal anesthesia. Endoscopists were asked to determine whether they believed that patients had received topical pharyngeal anesthesia and to estimate ease of esophageal intubation and procedure performance using a 100-mm visual analog scale. Procedure duration and doses of midazolam and meperidine were measured. RESULTS: The two groups did not differ with respect to age, gender, and previous endoscopic history. There were no significant differences between the two groups with respect to pretest anxiety, procedural comfort, and willingness to undergo subsequent examinations. Patients receiving topical pharyngeal anesthesia rated it as moderately unpleasant. Endoscopists were able to discriminate patients who received pharyngeal anesthesia from those who did not with a sensitivity of 0.73 and a specificity of 0.59. There were no significant differences between the two groups with respect to ease of intubation, procedure performance, procedure duration, and dosing of midazolam or meperidine. CONCLUSIONS: In patients undergoing diagnostic upper endoscopy using intravenous midazolam and meperidine, the use of topical pharyngeal anesthesia does not improve patient tolerance or procedure performance. Elimination of this agent in the performance of diagnostic upper endoscopy will save time and money without adversely affecting patient care or outcomes.

Anesthesia, Local↗

PubMed2003

[Bacteriological and epidemiological study on Neisseria gonorrhoeae isolated from the pharyngeal specimens of male and female patients with gonorrhea].

Neisseria gonorrhoeae were isolated from pharyngeal specimens of male and female patients and also from urethral and cervical discharges of male and female patients, respectively, suspected of having gonococcal infections in a urologic clinic in Kawasaki City. Microbiological and epidemiological studies were performed in 127 male and 41 female patients. The specimens were streaked onto the modified Thayer-Martin Selective Agar and the plates were incubated at 35 degrees C for 48 h under an atmosphere of 10% CO2. In 127 male patients, N. gonorrhoeae were detected in 117 (92.1%) of the urethral specimens. In these patients, N. gonorrhoeae were detected in pharyngeal specimens from 14 (11.0%) patients, but the pathogen was also detected in urethral specimens from these patients without exception. In 41 female patients. N. gonorrhoeae were detected in 20 (48.8%) of the 41 cervical discharges. When the pharyngeal specimens were tested, N. gonorrhoeae were detected in 14 (34.1%) of the 41 specimens. N. gonorrhoeae was simultaneously detected only in pharyngeal and cervical specimens from 11 of the 41 female patients and the pathogen was detected only in pharyngeal specimens from other 3 patients. There were no marked differences in antimicrobial susceptibilities between N. gonorrhoeae isolates from pharyngeal specimens and those from urethral or cervical discharges in all the patients tested. The PFGE patterns of 50 gonococcal isolates (25 pairs) from 25 patients (14 males and 11 females) in whom N. gonorrhoeae were simultaneously detected from pharyngeal and urethral or cervical specimens were analyzed. In 24 of 25 patients. N. gonorrhoeae isolated from the pharyngeal and urethral or cervical specimens in the same patients showed the same PFGE patterns. However, the 25 pairs showed the different PFGE patterns. From these results it is clarified that N. gonorrhoeae are detected in the pharyngeal specimens from considerable numbers of patients with gonorrhea, and there is a possibility that the pathogens prevailing among the patients differ in genetic sources.

Cervix Uteri↗

PubMed1996

Palatal and pharyngeal reflexes in health and in motor neuron disease.

Palatal and pharyngeal sensation and motor responses, and volitional palatal movement, were tested in 171 healthy adults and 43 patients with motor neuron disease. In healthy adults palatal and pharyngeal sensation and volitional palatal elevation were present in all; the palatal and pharyngeal motor responses could not be elicited on first testing in two (1.1%) and seven (4.1%) subjects respectively. Pharyngeal motor responses were more easily elicited in older subjects and palatal responses were more easily elicited in women. Eye watering and retching were the most common accompanying features. In 57 normal subjects tested on five occasions there was considerable variation in the stimulus required to elicit the motor responses within subjects: in none of four subjects (7%) who initially had absent responses were they always absent. Pharyngeal motor responses were more easily elicited in patients with motor neuron disease than in matched normal subjects; within the motor neuron disease group pharyngeal motor responses elicited by tongue depression were associated with the symptom of food or drink "going down the wrong way" > 1/month and a reduction in average volume per swallow (ml) and swallowing capacity (ml/s). Volitional palatal elevation was absent in five patients (11.6%). In six of eight patients with motor neuron disease studied repeatedly (on between two and seven occasions) the palatal and pharyngeal responses were elicited with the same stimulus on each occasion. In healthy adults palatal and pharyngeal sensation and motor responses should be present although considerable variation occurs in the stimulus required. In patients with motor neuron disease features of impaired swallowing are associated with a brisk rather than a depressed pharyngeal response.

Adolescent↗

PubMed1994

Influence of aging on oral-pharyngeal bolus transit and clearance during swallowing: scintigraphic study.

The aim of the study was to determine the influence of normal aging on regional transit and the efficiency of bolus clearance during the oral and pharyngeal phases of swallowing. We compared scintigraphically derived oral-pharyngeal transit times and isotope clearance during swallowing in 21 healthy aged volunteers (mean age 68 +/- 8 yr) and 9 young controls (mean age 28 +/- 7.5 yr). Subjects swallowed 5- and 10-ml water boluses mixed with 30 MBq 99mtechnetium tin colloid. Oral and pharyngeal transit times, pharyngeal clearance time, and postswallow residual counts in each region were derived from time-activity curves. Pharyngeal residual counts were significantly greater in the aged than in controls (P = 0.0008), but age did not influence oral residual. Aging significantly prolonged oral transit time (P = 0.02), pharyngeal transit time (P = 0.0004), and pharyngeal clearance time (P = 0.0001). We conclude that normal impairs the efficiency of pharyngeal clearance during swallowing, prolongs scintigraphic measures of oral-pharyngeal transit, and increases the exposure time of the glottis to the swallowed bolus.

Adult↗

PubMed1995

Enlargement of the lateral pharyngeal fat pad space in pigs increases upper airway resistance.

Because the upper airway is partially enclosed in a rigid boundary, enlargement of soft tissue structures within this boundary could narrow the airway. The purpose of this study was to determine whether enlargement of the soft tissue space in the region of the lateral pharyngeal fat pad would increase pharyngeal resistance and narrow the retropalateal upper airway. In five young male anesthetized pigs, we inserted balloon occlusion catheters in the lateral pharyngeal fat pad under computerized tomographic scan guidance. We measured pharyngeal resistance with a pharyngeal catheter and a tightly fitting face mask before and after inflation of the balloons. We also measured pharyngeal airway cross-sectional area before and after inflation of the balloons. In all pigs, balloon inflation significantly increased pharyngeal resistance and significantly decreased the area of the retropalateal airway. We conclude that enlargement of the soft tissue space in the region of the lateral pharyngeal fat pad increases pharyngeal resistance and narrows the retropalateal airway in anesthetized pigs.

Adipose Tissue↗

PubMed1996

Postural changes in respiratory airflow pressure and resistance in nasal, hypopharyngeal, and pharyngeal airway in normal subjects.

We investigated the effect of posture on nasal and pharyngeal resistance in 12 healthy subjects studied during wakefulness. Airway pressure and airflow were measured with subjects seated and in dorsal and left lateral recumbency, during inspiration and expiration. We found that pharyngeal resistance was approximately four to six times lower than the nasal resistance. Only pharyngeal resistance was significantly increased upon assumption of a supine posture, from 0.02 +/- 0.01 Pa/mL per second when seated to 0.06 +/- 0.05 Pa/mL per second in dorsal recumbency and to 0.05 +/- 0.04 Pa/mL per second in left lateral recumbency. Mean nasal and pharyngeal resistances doubled upon assumption of a supine posture, but this difference was not statistically significant. There was no significant difference in pharyngeal resistance between inspiration and expiration. Finally, there was a strong linear relationship between pharyngeal pressure and pharyngeal resistance (r = .98, p<.0001). We concluded that in normal awake subjects 1) pharyngeal resistance increases with assumption of a supine posture, 2) the walls of the pharynx are not compliant enough to alter their resistance in response to inspiratory and expiratory pressure changes, and 3) it may be possible to infer pharyngeal resistance from measurements of pressure alone, without measurement of airflow.

Adult↗

PubMed1994

The pha-4 gene is required to generate the pharyngeal primordium of Caenorhabditis elegans.

In the 4-cell Caenorhabditis elegans embryo, two blastomeres are destined to generate pharyngeal cells, each by a distinct developmental strategy: one pathway is inductive, while the other is autonomous. Here, we identify the pha-4 locus. In animals lacking pha-4 activity, an early step in pharyngeal organogenesis is blocked: no pharyngeal primordium is formed and differentiated pharyngeal cells are absent. Most other tissues are generated normally in pha-4 mutants, including cells related to pharyngeal cells by cell lineage and position. Thus, pha-4 activity is required to form the pharyngeal primordium. We propose that pha-4 marks a convergence of the inductive and autonomous pathways of pharyngeal development and suggest that establishment of pharyngeal organ identity is a crucial step for pharyngeal organogenesis.

Animals↗

PubMed1994

The Caenorhabditis elegans NK-2 class homeoprotein CEH-22 is involved in combinatorial activation of gene expression in pharyngeal muscle.

The pharyngeal muscles of Caenorhabditis elegans are single sarcomere muscles used for feeding. Like vertebrate cardiac and smooth muscles, C. elegans pharyngeal muscle does not express any of the known members of the MyoD family of myogenic factors. To identify mechanisms regulating gene expression in this tissue, we have characterized a pharyngeal muscle-specific enhancer from myo-2, a myosin heavy chain gene expressed exclusively in pharyngeal muscle. Assaying enhancer function in transgenic animals, we identified three subelements, designated A, B and C, that contribute to myo-2 enhancer activity. These subelements are individually inactive; however, any combination of two or more subelements forms a functional enhancer. The B and C subelements have distinct cell type specificities. A duplication of B activates transcription in a subset of pharyngeal muscles (m3, m4, m5 and m7). A duplication of C activates transcription in all pharyngeal cells, muscle and non-muscle. Thus, the activity of the myo-2 enhancer is regulated by a combination of pharyngeal muscle-type-specific and organ-specific signals. Screening a cDNA expression library, we identified a gene encoding an NK-2 class homeodomain protein, CEH-22, that specifically binds a site necessary for activity of the B subelement. CEH-22 protein is first expressed prior to myogenic differentiation and is present in the same subset of pharyngeal muscles in which B is active. Expression continues throughout embryonic and larval development. This expression pattern suggests CEH-22 plays a key role in pharyngeal muscle-specific activity of the myo-2 enhancer.

Animals↗