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To elucidate the mechanisms underlying pharynx regeneration in planarians, we transplanted pieces excised from various regions of the body into the prepharyngeal or postpharyngeal region, since it has been shown that such transplantation experiments can induce ectopic pharynx formation. We confirmed the ectopic formation of pharynxes by expression of the myosin heavy chain gene specific to pharynx muscles (DjMHC-A). To investigate the cellular events after grafting, we also stained such transplanted worms by in situ hybridization using neuronal cell- and mucous producing cell-type-specific marker genes which can detect formation of brain and prepharyngeal region, respectively. When the head piece was transplanted into the tail region, ectopic formation of the head, prepharyngeal and pharynx region was observed in the postpharyngeal region anterior to the graft, while these organs were formed in the reversed polarity along the anterior-posterior (A-P) axis. Furthermore, in the tail region posterior to the graft, ectopic formation of the prepharyngeal and pharynx region was observed. In the reverse combination, when a tail piece was transplanted into the prepharyngeal region, ectopic formation of prepharyngeal and pharynx region was observed in the region between the head and the graft, and an additional ectopic pharynx was also formed in reverse polarity in the region between the graft and host pharynx. These results clearly indicated that ectopic pharynxes were formed as a consequence of the regional reorganization induced by interaction between the host and graft. Furthermore, chimeric analyses demonstrated that the cells participating in ectopic pharynx formation were not exclusively derived from the host or donor cells in the worm, suggesting that the stem cells of the host and donor may change their differentiation pattern due to altered regionality. To further investigate if regional reorganization is induced after grafting, expression of a Hox gene was analyzed in the transplanted worms by whole-mount in situ hybridization. The expression of the Hox gene along the A-P axis was apparently rearranged after grafting of the head piece into the tail region. These results suggest that grafting of the head piece may rearrange the regionality of the host tail, and that stem cells in the region newly defined as pharynx-forming may start to regenerate a pharynx.
To understand the cellular events during planarian regeneration, we analyzed the process of pharynx regeneration in both head and tail pieces using cell-type-specific markers. Interestingly, cells expressing the pharynx-muscle-specific myosin heavy chain gene (DjMHC-A) appeared within 24 h after amputation (prior to the formation of a pharynx rudiment) in the mesenchymal space of the stump, not in the blastema region. These DjMHC-A-positive cells migrated to the midline and formed the pharynx rudiment. Even after formation of the pharynx rudiment, DjMHC-A-positive cells constantly appeared in the mesenchymal space in the region surrounding the pharynx rudiment and participated in the growth of the pharynx rudiment. These observations clearly indicated that the cells involved in pharynx-muscle formation are committed in the mesenchymal space of the stump, rather than in the blastema region or the pharynx rudiment during planarian regeneration. We also analyzed the process of regeneration of the pharynx epithelia using a monoclonal antibody and investigated the origin of the pharynx epithelia.
Planarian cell renewal is achieved as a result of proliferation and differentiation of totipotent undifferentiated cells called neoblasts. The absence of mitosis within the planarian pharynx raises the question as to how cell renewal and growth occur within this organ. Two explanations have been advanced: one proposes that new cells remain close to the base of the pharynx, which then grows by distal displacement of older cells, and the other suggests that the new cells are intercalated between older cells throughout the pharynx. The second alternative, however, does not explain how new cells enter the pharynx or how they reach their final destination. In this study of myosin heavy-chain gene expression within planarian pharynx, a row of differentiating myocytes was detected all along the pharynx parenchyma. According to the hybridization pattern, all these myocytes appeared to be at early stages of differentiation. These data favour an intercalary model for muscle cell renewal within the pharynx. According to this model, neoblasts at the base of the pharynx would enter the pharynx, where they would start differentiation to myocytes, move to the subepithelial musculature and intercalate between the old muscle cells. The possible application of this intercalary model to other pharynx cell types is also discussed.
BACKGROUND: Endosonography is a diagnostic tool for the examination of tumors of the oral cavity. The pharynx is usually not assessable for conventional endosonography due to problems with the placement of the probe in deeper areas of the pharynx. PATIENTS: A fingertop ultrasonography probe was combined with a stick allowing the user to locate the probe in deeper areas of the pharynx. The stick had two flexible joints and a device for attaching the probe in the front. We evaluated 48 patients with tumors of the posterior wall of the pharynx (n = 6), lateral wall of the pharynx (n = 7), tonsil (n = 17), sinus piriformis (n = 13), and nasopharynx (n = 5) during preoperative tumor endoscopy under general anesthesia. Thirty-two patients suspected of having a tonsillar abscess were examined under local anesthesia. RESULTS: The evaluation of the tumor dissemination and the determination of the relationship between the tumor and the internal carotid artery was excellent for tumors of the posterior and lateral wall of the pharynx. The investigation of tumors of the sinus piriformis and the nasopharynx was difficult and tumor growth could not be determined normally with endosonography. In four cases, retropharyngeal lymph nodes could be detected. The sensitivity for the diagnosis of tonsillar abscesses was 84%. CONCLUSION: Endosonography of the deeper areas of the pharynx seems to be a useful instrument for investigating growth of tumors at the lateral and posterior wall of the pharynx. Endosonographic results might be helpful for deciding between endoscopic and external approaches. Endosonography is not sufficiently sensitive for diagnosing tonsillar abscesses, but might be helpful in clinically difficult cases.
Patency of the collapsible segment of the pharynx is dependent upon the interplay of anatomic and physiologic factors. The upper airway of the typical patient with obstructive sleep apnea (OSA) is structurally narrowed by fat deposits in the lateral pharyngeal walls. During wakefulness, the upper airway dilator muscles compensate for the structurally reduced pharyngeal size by increasing their activity, thereby pulling the tongue and soft palate forward. As a consequence, the cross-sectional area is relatively preserved, but the shape of the pharynx becomes elliptical along the anteroposterior axis. In the awake patient with OSA, patency of the pharynx is largely dependent upon increased dilator muscle activity. During sleep, the activity of the muscular apparatus of the pharynx decreases causing a critical narrowing. Because anatomic narrowing appears to be a basic feature, enlarging the pharynx should be beneficial, particularly if its lateral diameter can be increased. Whereas facial advancement surgery structurally increases the anteroposterior diameter of the pharynx, thereby accounting for the good results reported with this technique, it is doubtful that uvulopalatopharyngoplasty has a similar effect on either the anter-oposterior or lateral diameters of the pharynx.
We examined the reproducibility of capsaicin-induced cough thresholds and the influence of pharynx anaesthesia used to treat the cough. We performed cough threshold tests on ten patients with bronchial asthma and ten patients with chronic cough. The lowest level of capsaicin-induced cough threshold was defined as ten coughs. Tachyphylaxis in cough thresholds was examined three times at intervals of 30 minutes and 120 minutes after the initial test. We measured cough thresholds before and after pharynx anaesthesia with xylocainbiscus. There was no change in cough thresholds among the three times; nor was them any change in the thresholds before and after pharynx anaesthesia. But in five patients with acute pharyngitis, the cough thresholds after pharynx anaesthesia were greater than before. It was suggested that cough threshold tests had reproducibility 30 minutes and 120 minutes after indicating that tachyphylaxis did not exist. Furthermore it was suggested that pharynx anaesthesia influenced the cough threshold in patients with acute inflammation of the pharynx, but anesthesia had no influence on cough thresholds in patients without acute inflammation of the pharynx.
BACKGROUND: Nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection in infants has become a serious concern and a new means of preventing the transmission of MRSA in the community needs to be considered. METHODS: We performed nasal mupirocin treatment on 10 infants who were MRSA-positive either in the nose or the pharynx and evaluated the effect of mupirocin on the eradication of MRSA. RESULTS: Eradication of MRSA from the nose was successful in two cases and eradication from the pharynx in six (66.6%) of nine cases. The number of treatments required to achieve eradication varied; within three courses for nose carriers and from one to seven courses for pharynx carriers. Eradication was unsuccessful even after five to seven treatments in three pharynx-limited carriers. CONCLUSIONS: These data suggest that the effect of nasal mupirocin treatment on pharynx-colonized MRSA is limited and that repetitive treatment is necessary in some cases. However, in view of the possibility of preferential pharyngeal colonization of Staphylococcus aureus in infancy, nasal mupirocin treatment deserves further evaluation for eradication not only of nose- but also of pharynx-colonized MRSA.
PURPOSE: The authors correlated the radiographic evaluation and 24-hour pH monitoring of the pharynx and the esophagus in patients with globus pharyngeus. MATERIALS AND METHODS: Radiographic examination of the pharynx of 22 patients (13 women and nine men, aged 23-73 years [mean, 47 years]) included videofluoroscopy and static radiography. Twenty-four-hour double-probe pH monitoring of the pharynx (abnormal, pH < 4) and esophagus (abnormal, 6% or more total acid exposure) was performed in all patients. RESULTS: Radiographic results were normal in 17 patients; results were abnormal in five, with four having pharyngeal dysfunction and one showing a persistent cricopharyngeal impression. Zenker diverticulum was not seen. Results at pH monitoring of the pharynx and esophagus were normal in 20 and 18 of the 22 patients, respectively. In four of five patients with abnormal radiographic studies of the pharynx, results of pharyngeal pH monitoring were normal. CONCLUSION: Most patients with globus pharyngeus had normal results at pH monitoring and radiographic examination of the pharynx.
PURPOSE: To determine the prevalence and severity of functional abnormalities of the pharynx relative to patient age and symptoms. MATERIALS AND METHODS: Radiographic evaluation of the pharynx was performed in 110 consecutive outpatients aged 19-84 years old who had no previous surgery of the larynx, pharynx, or esophagus. Each patient completed a symptom data sheet, and we reviewed medical records to determine the main indication for each examination. Videofluoroscopy and static filming in frontal and lateral positions were done with 20-ml barium boluses. We then evaluated functional abnormalities and classified abnormal findings by type and severity. RESULTS: We categorized patients by age into three groups: less than 40 years old (n=31), between 40 and 60 years old (n =42), and greater than 60 years old (n=37). We found a significant increase in the prevalence (23%, 36%, 57%, respectively) and severity of functional abnormalities of the pharynx in older patients (p < .05). Laryngeal penetration, aspiration, pharyngeal stasis, and cricopharyngeal bar were the main abnormalities found in the two older groups. However, we found no correlation between functional abnormalities of the pharynx and symptoms and indications (p > .05). CONCLUSION: Functional abnormalities of the pharynx increased in prevalence and severity with age. Often these findings were not related to specific pharyngeal symptoms and must be interpreted cautiously in older patients.
Transient relaxation of the lower esophageal sphincter (LES) is observed fairly frequently during prolonged continuous monitoring of the LES. The aim of this study was to test whether the presence of a catheter in the pharynx through the stimulation of mechanoreceptors may induce transient LES relaxation. LES and esophageal pressure recordings were obtained for 1 hour in six subjects with a manometric catheter placed via a gastrostomy tube. Swallowing was monitored by submental electromyographic recording. Additional recordings were obtained in these subjects with a catheter placed in the pharynx for 1 additional hour. Transient LES relaxations were recorded in both study periods, i.e., with and without a catheter in the pharynx. The frequency of transient LES relaxations was significantly higher in the presence of manometric catheters in the pharynx (6.4 +/- 2.2 vs. 2.0 +/- 1.1 total LES relaxations). The frequency of transient LES relaxation during the first and second hour after placement of the manometric catheter in a group of seven healthy subjects was not significant different. It is concluded that the pharynx is one of the sites that may mediate the induction of transient LES relaxation.
The rhythmic contraction of the Caenorhabditis elegans pharynx is unique in that the network of 12 neurons, including two M3 neurons, that regulate the contraction is known. The neurotransmitters secreted by these cells, and the target cells responding to these chemical signals, are not known. Here, we describe an approach to obtain this missing information and use the M3 cells as an example. Electrical recordings (electropharyngeograms) were used in conjunction with temporally and spatially defined application of neurotransmitters via photolysis of inactive, photolabile precursors. To illustrate the technique we used pharyngeal preparations in which the two M3 neurons are intact and preparations in which they were removed by laser irradiation. Removal of M3 neurons results in the loss of the small negative peaks in the electropharyngeograms and an increase in time during which the pharynx remains contracted. We demonstrate that the application of glutamate by photolysis of caged glutamate to a pharynx from which the two M3 neurons were removed produces effects similar to those observed before removal of the M3 neurons. In control experiments, photolytic release from photolabile precursors of carbamoylcholine, a stable and well characterized analog of acetylcholine, or of gamma-aminobutyric acid, from photolabile precursors did not have this effect. The response depended on the amount of glutamate released. By reducing the size of the photolytic beam, glutamate was released at several different locations of the pharynx. Two areas of the pharynx mainly respond to the application of glutamate; one corresponds to the pm4 muscle cells in the metacorpus, and the other to the junction between muscle cells pm5 in the isthmus and pm6 in the terminal bulb.
BACKGROUND: Pharyngeal airway devices can exert substantial pressures against the pharyngeal mucosa. The authors assess the relation between pharyngeal mucosal perfusion and directly measured mucosal pressure (MP) in the posterior pharynx using a fiberoptic technique with a modified cuffed oropharyngeal airway (COPA). The authors also measure in vivo intracuff pressure (CP), airway sealing pressure and MP at four locations using an unmodified COPA. METHODS: Twenty adult patients, American Society of Anesthesiologists status I or II, undergoing general anesthesia were allocated randomly to receive either (1) a COPA with a millimeter microchip sensor fixed on the external cuff surface to record distal posterior pharyngeal MP or (2) a COPA with a fiberoptic scope inserted inside the cuff to record digitized images of the distal posterior pharyngeal mucosa. MP and digitized images were obtained at the same location over an in vivo CP range of 10-160 cm H2O in 10- to 20-cm H2O increments. The digitized images were scored according to blood vessel caliber and mucosal color by two investigators blinded to MP and CP. In an additional 20 matched patients, in vivo CP, airway sealing pressure, and MP was measured at four different cuff locations (corresponding to the anterior, lateral, and posterior pharynx and the distal oropharynx) with increasing cuff volume. RESULTS: Blood vessel caliber and mucosal color was normal in all patients when the mean mucosal pressure was 17 cm H2O. Blood vessel caliber was first reduced when the mean mucosal pressure was 34 cm H2O. There was a progressive incremental reduction in blood vessel caliber and mucosal color when the mean mucosal pressure increased from 34 to 80 cm H2O (P < or = 0.05). Complete blood vessel collapse and mucosal paling first occurred with the mean mucosal pressure was 73 cm H2O and was present in 90% of patients when the mean mucosal pressure was 80 cm H2O. Mean MP was always higher in the posterior pharynx compared with the other locations when the cuff volume was 20 ml or greater (P < 0.001). In vivo CP is an excellent predictor of mucosal pressure. Mean (95% confidence interval [CI]) MP in the posterior pharynx was 35 (5-67) and 78 (50-109) cm H2O when the airway sealing pressure was 10 (6-16) and 17 (13-21) cm H2O respectively. CONCLUSION: Pharyngeal mucosal perfusion is reduced progressively in the posterior pharynx when MP is increased from 34 to 80 cm H2O with the COPA. CP provides reliable information about MP and should be less than 120 cm H2O to prevent mucosal ischemia.
The anatomy of the pharynx of Caenorhabditis elegans has been reconstructed from electron micrographs of serial sections. The pharynx is used for pumping food into the gut, and is composed of 34 muscle cells, 9 marginal cells, 9 epithelial cells, 5 gland cells and 20 neurones. Three regions of specialization in the cuticle lining of the pharyngeal lumen may aid in the accumulation of food particles. A basement membrane isolates the pharynx from the rest of the animal, making the pharyngeal nervous system a nearly self-contained unit which is composed primarily of five classes of motor neurones and six classes of interneurones. Three other classes have also been described, which by their morphology appear to be neurosecretory and motor, motor and interneuronal, and lastly one pair that only innervates three of the marginal cells. Some classes of neurone have free endings just under the cuticle lining the lumen of the pharynx, suggesting that these are mechano- or proprio-receptive endings. The connectivity of these neurones has been described at the level of individual synaptic regions, and after combining this information with video taped observations of the pharynx pumping, some interpretations of how these neurones function have been offered.
A three-dimensional numerical modeling of airflow in the human pharynx using an anatomically accurate model was conducted. The pharynx walls were assumed to be passive and rigid. The results showed that the pressure drop in the pharynx lies in the range 200-500 Pa. The onset of turbulence was found to increase the pressure drop by 40 percent. A wide range of pharynx geometries covering three sleep apnea treatment therapies (CPAP, mandibular repositioning devices, and surgery) were modeled and the resulting flow characteristics were investigated and compared. The results confirmed that the airflow in the pharynx lies in the laminar-to-turbulence transitional flow regime and thus, a subtle change in the morphology caused by these treatment therapies can significantly affect the airflow characteristics.