Swallowing-like activity elicited in neonatal rat medullary slice preparation.

Swallowing is induced by a central pattern generator in the nucleus tractus solitarius (NTS). We aimed to create a medullary slice preparation to elucidate the neural architecture of the central pattern generator of swallowing (Sw-CPG) and record its neural activities. Experiments were conducted on 2-day-old Sprague-Dawley rats (n = 46). The brainstem-spinal cord was transected at the pontomedullary and cervicothoracic junctions; the medulla was sliced transversely at thicknesses of 600, 700, or 800 µm. The rostral end of the slice was 100 µm rostral to the vagus nerve. We recorded hypoglossal nerve activity and electrically stimulated the vagus nerve or microinjected bicuculline methiodide (BIC) into the NTS. The 800-µm slices generated both rhythmic respiratory activity and electrically elicited neural activity. The 700-µm slices generated only respiratory activity, while the 600-µm slices did not generate any neural activity. BIC microinjection into the NTS in 800-µm slices resulted in the typical activity that closely resembled the swallowing activity reported in other experiments. This swallowing-like activity consistently lengthened the respiratory interval. Despite complete inhibition of respiratory activity, weak swallowing-like activity was observed under bath application of a non-NMDA receptor antagonist. Contrastingly, bath application of NMDA receptor antagonists resulted in a complete loss of swallowing-like activity and no change in respiratory activity. These results suggest that the 800-µm medullary slice preparation contains both afferent and efferent neural circuits and pattern generators of swallowing activity. Additionally, NMDA receptors may be necessary for generating swallowing activity. This medullary slice preparation can therefore elucidate Sw-CPG neural networks.

Maxillary Development and Dental Arch Relationships Following Early Two-Stage Palatoplasty: A Comparative Study.

OBJECTIVE: To examine skeletal morphology and dental arch relationships at 8 years of age following early 2-stage palatoplasty, which consists of soft palate plasty at 1 year of age and hard palate closure at 1.5 years of age, and to compare the results with those of conventional pushback palatoplasty. DESIGN: Retrospective. SETTING: Single institutional study. PATIENTS: Eighty-six patients with nonsyndromic complete unilateral cleft lip and palate (UCLP) were selected. INTERVENTION: The subjects were divided into 2 groups according to the palatoplasty protocols, as follows: 45 patients, who underwent early 2-stage palatoplasty (ETS group), and 41 patients, who underwent 1-stage pushback palatoplasty (PB group). MAIN OUTCOME MEASURES: Skeletal morphology was assessed using lateral cephalometric analysis, and dental arch relationships were examined using the GOSLON yardstick. RESULTS: Cephalometric analysis revealed that the anterior-posterior length of the maxilla, measured by PTM-A and PTM-ANS, both projected to the nasal floor (NF) plane, was longer in the ETS group than in the PB group (PTM-A/NF, p = .04; PTM-ANS/NF, p = .03, unpaired t-test), although no significant difference was observed in SNA (p = .09, unpaired t-test). Upper posterior facial height was shorter in the ETS group than in the PB group (p = .02, unpaired t). Assessments with the GOSLON yardstick showed that the ETS group presented better dental arch relationships than the PB group (p = 0.04, Mann-Whitney's U-test). CONCLUSIONS: The present results suggested that the ETS protocol reduced the negative effects of palatal surgery on facial development and dental arch relationships in patients with complete UCLP at 8 years of age.

Occlusion at 5 Years of Age Following Hard Palate Closure With Vestibular Flap.

OBJECTIVE: This study aims to assess occlusal relationships and frequency of oronasal fistula at 5 years of age following 2 hard palate closure techniques and to compare results. DESIGN: Retrospective longitudinal study. SETTING: Institutional study. PATIENTS: Study patients included 57 patients with nonsyndromic complete unilateral cleft lip and palate who were consecutively treated. All patients underwent our early 2-stage protocol for palatoplasty, which consisted of soft palate plasty at 1 year of age and hard palate closure at 1.5 years of age. Twenty-nine patients underwent hard palate closure using vestibular flap (VF group) technique (2009-2011) and 28 patients underwent conventional hard palate closure with local palatal flap (LPF group) technique (2006-2008). MAIN OUTCOME MEASURES: Occlusal relationships were assessed with 5-year-olds' index, and frequency of oronasal fistula was investigated. RESULTS: Average 5-year-olds' index scores for VF and LPF groups were 3.11 and 3.57, respectively (P < .001). Oronasal fistula occurred in approximately 7% of patients in the VF group and in 18% of patients in the LPF group. CONCLUSION: Hard palate closure with VF technique may provide better occlusal relationships at 5 years of age than does conventional local closure with the LPF.