The effect of cleft palate repair on contractile properties of single permeabilized muscle fibers from congenitally cleft goat palates

A new congenital cleft palate New Zealand rabbit model for surgical research

Cleft palate repair is a challenging procedure for cleft surgeons to teach, and in research, it can be difficult to evaluate different techniques and develop new treatments. In this study, a congenital cleft palate New Zealand rabbit model has been described and could be beneficial in future studies concerning cleft palate repair. Pregnant New Zealand rabbits received 1.0 mg dexamethasone injection intramuscularly once a day from the 13th gestation day (GD13) to GD16. On GD31. Newborn rabbits were delivered by cesarean sections, fed with a standardized gastric tube feeding method, and divided into two groups. The rate of survival and the incidence of cleft palate was calculated. Weight, appearance, behavior, maxillary occlusal view, and regional anatomic and histological comparisons were recorded within 1 month after birth. Infants from the two groups with similar physiological conditions were selected for continuous maxillofacial and mandibular Micro-CT scan and three-dimensional reconstruction analysis. Ten pregnant rabbits gave birth to 48 live infants. The survival and cleft palate rates were 65.6% and 60.4% respectively. Both groups survived over 1 month with no difference in weight, appearance, and behavior. The cleft type was stable, and anatomical defects, histological characteristics, and nasal-maxillary abnormalities of the cleft were similar to those of humans. There was no statistically significant difference in maxillary and mandible development between the two groups within one month after birth. This congenital cleft palate model is considered to have more research possibilities with efficient cleft induction, reliable feeding methods, stable anatomical defects, and maxillofacial development similar to those seen in humans.

Structural Changes Following Velopharyngeal Resistance Training (Continuous Positive Airway Pressure Therapy): A Preliminary Report

OBJECTIVE

To evaluate the feasibility/effectiveness of using magnetic resonance imaging (MRI) to document velopharyngeal (VP) structural changes induced by continuous positive airway pressure (CPAP) therapy.

OUTCOME MEASURES

Changes in velar length and thickness, levator veli palatini (LVP) length and thickness, velar volume, and intravelar muscular proportion along the course of CPAP therapy participation (Pre-CPAP, Post-CPAP, and withdrawal).

RESULTS

Velar and LVP lengths remained nearly the same, with the median changes (Δ) less than 0.6%, across repeated conditions. Although varying in magnitudes of change, median velar volume (Δ4%), velar thickness (Δ20%), LVP thickness (Δ17%), and intravelar muscular proportion (Δ10%) illustrated a consistent pattern of increases following the 8-week CPAP therapy. These VP structural measurements slightly decreased but remained above the pretraining condition after 8-week detraining.

CONCLUSIONS

This report successfully demonstrated that MRI is a viable tool to document CPAP therapy-induced VP structural changes while providing preliminary empirical data.

Power output of skinned skeletal muscle fibres from the cheetah (Acinonyx jubatus)

Muscle samples were taken from the gluteus, semitendinosus and longissimus muscles of a captive cheetah immediately after euthanasia. Fibres were 'skinned' to remove all membranes, leaving the contractile filament array intact and functional. Segments of skinned fibres from these cheetah muscles and from rabbit psoas muscle were activated at 20°C by a temperature-jump protocol. Step and ramp length changes were imposed after active stress had developed. The stiffness of the non-contractile ends of the fibres (series elastic component) was measured at two different stress values in each fibre; stiffness was strongly dependent on stress. Using these stiffness values, the speed of shortening of the contractile component was evaluated, and hence the power it was producing. Fibres were analysed for myosin heavy chain content using gel electrophoresis, and identified as either slow (type I) or fast (type II). The power output of cheetah type II fibre segments was 92.5±4.3 W kg(-1) (mean ± s.e., 14 fibres) during shortening at relative stress 0.15 (the stress during shortening/isometric stress). For rabbit psoas fibre segments (presumably type IIX) the corresponding value was significantly higher (P<0.001), 119.7±6.2 W kg(-1) (mean ± s.e., 7 fibres). These values are our best estimates of the maximum power output under the conditions used here. Thus, the contractile filament power from cheetah was less than that of rabbit when maximally activated at 20°C, and does not account for the superior locomotor performance of the cheetah.

Strategies to improve regeneration of the soft palate muscles after cleft palate repair

Children with a cleft in the soft palate have difficulties with speech, swallowing, and sucking. These patients are unable to separate the nasal from the oral cavity leading to air loss during speech. Although surgical repair ameliorates soft palate function by joining the clefted muscles of the soft palate, optimal function is often not achieved. The regeneration of muscles in the soft palate after surgery is hampered because of (1) their low intrinsic regenerative capacity, (2) the muscle properties related to clefting, and (3) the development of fibrosis. Adjuvant strategies based on tissue engineering may improve the outcome after surgery by approaching these specific issues. Therefore, this review will discuss myogenesis in the noncleft and cleft palate, the characteristics of soft palate muscles, and the process of muscle regeneration. Finally, novel therapeutic strategies based on tissue engineering to improve soft palate function after surgical repair are presented.

Three-dimensional magnetic resonance imaging of velopharyngeal structures

PURPOSE

To report the feasibility of using a 3-dimensional (3D) magnetic resonance imaging (MRI) protocol for examining velopharyngeal structures. Using collected 3D MRI data, the authors investigated the effect of sex on the midsagittal velopharyngeal structures and the levator veli palatini (levator) muscle configurations.

METHOD

Ten Caucasian healthy adults (5 women and 5 men) participated. A whole-head 3D MRI scan was obtained while participants were at rest in the supine position. Basic anatomic parameters of the velopharynx including midsagittal velopharyngeal structures and levator muscle configurations were compared between sexes.

RESULTS

Detailed information on the 3D MRI protocol and data analysis method was introduced in the study. On the basis of the data, only the length of the levator muscle showed a statistically significant sex difference: Male participants had significantly longer levator muscles than those of female participants.

CONCLUSIONS

The present study successfully demonstrated the use of 3D MRI in quantifying major velopharyngeal structures and provided additional data on the anatomic variations that exist in healthy adult individuals.

Magnetic resonance imaging assessment of velopharyngeal motion in chinese children after primary palatal repair

BACKGROUND

Velopharyngeal inadequacy (VPI), which has a significant negative impact on speech intelligibility and resonance quality, may be caused by physiological inadequacy. The current study aimed to investigate the maximal velar and pharyngeal motions and levator muscle shortening in the children with repaired cleft palate and different speech outcomes as well as children without cleft palate by using magnetic resonance imaging techniques without general anesthesia.

METHODS

Three groups of sex- and age-matched children were recruited: children with repaired cleft palate and adequate velopharyngeal function condition (VPC), children with repaired cleft palate and VPI, and the normal controls (noncleft). The children were trained to perform sustained /a:/, /i:/, /ts:/, and /m:/, while keeping the head still during magnetic resonance imaging scan. The maximal velar elevation and stretch, pharyngeal medial constriction, velopharyngeal ratio (VP ratio), and levator muscle shortening ratio were measured and compared across the 3 groups.

RESULTS

The VPI group showed the least maximal velar stretch, lowest maximal velar height, smallest maximal pharyngeal constriction, and lowest maximal VP ratio among the 3 groups. The VPI and VPC groups differed significantly in velar and pharyngeal mobility. The effective VP ratio at rest has a strong correlation with that during sustained phonation across the 3 groups. The maximal velar stretch ratio correlates to the maximal pharyngeal constriction ratio strongly in the VPI group only.

CONCLUSIONS

The VPI group had significantly reduced velar and pharyngeal mobility during speech compared with the VPC and noncleft groups. The possible physiological causes of VPI after primary palatal repair were discussed.

The effect of cleft palate repair on contractile properties of single permeabilized muscle fibers from congenitally cleft goat palates

Inherent differences in the levator veli palatini (LVP) muscle of cleft palates before palatoplasty may play a role in persistent postrepair velopharyngeal insufficiency (VPI). Contractile properties of LVP muscle fibers were analyzed from young (2-month) normal (YNP), young congenitally cleft (YCP) and again on the same YCP subjects 6 months after palatoplasty, mature repaired palate (MRP). The cross-sectional area and rate of force development (ktr) were measured. Specific force (sF(0)) and normalized power (nP(max)) were calculated. Using k(tr) to determine fiber type composition, YNP was 44% type 1 and 56% type 2, while YCP was 100% type 2. Two MRP subjects shifted to 100% type 1; 1 demonstrated increased resistance to fatigue. No differences in sF(0) were observed. nP(max) increased with presence of type 2 fibers. The persistent state of type 2 fibers following palatoplasty leads to increased fatigue in the LVP of MRP subjects and may cause VPI symptoms.