The effect of unilateral partial facial paralysis on nasofrontal sutural growth: an experimental study in the rabbit.

In a previous study in the rabbit, it was demonstrated that paralysis of the midfacial musculature results in decreased anteroposterior growth of the snout. At the end of growth, these animals showed macroscopically striking similarities to animals with unilateral fusion of the nasofrontal suture. In this study, whether nasofrontal sutural growth is unilaterally restricted in animals with unilateral partial facial paralysis was investigated. A left-sided partial facial paralysis was induced in sixteen 12-day-old New Zealand White rabbits. At the ages of 5, 9, 12, and 17 weeks, four animals were randomly assigned to be killed for analysis of nasofrontal sutural growth. In each animal, the left experimental side was compared with the right control side. By means of histomorphometric measurements, it was shown that diminished sutural growth activity was present on the left paralyzed side in periods of rapid growth. On the other hand, no significant alterations in sutural width were found. These findings seem to explain some of the macroscopic growth alterations (i.e., diminished anterior maxillary length) observed in rabbits with unilateral partial facial paralysis.     

Effect of nerve repair after unilateral partial facial paralysis on craniofacial growth and development

The effect of partial transection, coaptation, and freezing of the left facial nerve on craniofacial growth and development was investigated. Twelve-day-old New Zealand White rabbits were randomly assigned to four groups: control group (n = 15), nerve ablation group (n = 15) with a surgically induced partial facial paralysis, nerve coaptation group (n = 15) with a surgically induced partial facial paralysis treated by immediate microsurgical nerve coaptation, and nerve freezing group (n = 13) with a freezing-induced partial facial paralysis. All animals were operated on at the age of 12 days; follow-up evaluations were performed at the ages of 2 months (end-point prepubertal growth) and 6 months (full grown). Computerized dorsoventral roentgencephalometric analysis and computer tomographic three-dimensional volumetric measurements were performed at both ages. Roentgencephalometric analysis revealed that the growth disturbances of the nerve ablation group and the nerve coaptation group were analogous. In contrast, in the nerve freezing group, hardly any growth disturbances as compared with the control group were seen. The CT volume measurements revealed a significant left-right difference in maxillary volume at the ages of 2 and 6 months in the nerve coaptation group as compared with the control group. Muscle histomorphometric analysis revealed a shift in muscle fiber composition in the nerve coaptation group and the nerve freezing group, with an increase of type I fibers at the cost of type IIA fibers. This shift was significantly less pronounced in the latter than in the former. Nerve histomorphometric analysis revealed a significant increase in the number of nerve fibers in the nerve coaptation group as compared with the control group. In the nerve freezing group, the increase in the number of nerve fibers was not significantly different as compared with the control group and the nerve coaptation group. Both the equivalent diameter and the myelin area were equally reduced in the nerve coaptation and nerve freezing groups. Thus, the nerve coaptation group and the nerve freezing group did not differ significantly in the extent of nerve recovery, although they differed in the extent of muscle recovery. The extent of muscle recovery, in turn, was related to the extent of abnormal craniofacial growth and development. Indeed, the growth and development were hardly abnormal in the nerve freezing group and as abnormal as after untreated paralysis in the nerve coaptation group. Therefore, factors related to nerve regeneration, other than those assessed by nerve histomorphology, were considered to be responsible for these differences between both groups. The duration of the denervation time was regarded to be considerably shorter in the nerve freezing group than in the nerve coaptation group, resulting in the observed improved muscle recovery. The difference in the degree of axonal malalignment between both groups was considered to be negligible, because of the tolerance toward axonal malalignment at neonatal age.     

Effect of unilateral partial facial paralysis on periosteal growth at the muscle-bone interface of facial muscles and facial bones

In a previous study, the influence of the midfacial musculature upon growth and development of the maxilla and mandible was established macroscopically. Dry skull measurements revealed a reduced premaxillary, maxillary, mandibular, and anterior corpus length with a simultaneous increase in mandibular ramal height on the paralyzed side. It was demonstrated that these reduced premaxillary and maxillary lengths were among others the result of reduced nasofrontal growth, whereas the increased ramal height was accompanied by condylar growth alterations. This study investigated whether the growth alterations at the mandibular corpus region could be explained by altered periosteal growth at the muscle-bone interface of the zygomatico-auricular muscle and the mandibular corpus, caused by altered muscle activity acting upon the periosteal sleeve. Fifty-six 12-day-old New Zealand White rabbits were randomly assigned to either a control or an experimental group. In the experimental group, left-sided partial facial paralysis was induced surgically when the animals were 12 days old. To study the muscle-bone interface, seven follow-up time intervals were defined between 3.5 and 60 days following the surgery. At these time intervals, four randomly selected control animals and four randomly selected experimental animals were killed. The anterior mandibular corpus region with the muscle-bone interface of the left control hemimandible and the left and right experimental hemimandibles was processed for undecalcified tissue preparation. Quantitative analysis of the total bone area at the muscle-bone interface revealed no significant differences between the left control hemimandible and the left and right experimental hemimandibles. Also, qualitative study of the histologic sections showed no major changes in the appearance or development of the trabecular pattern between the groups. However, slight differences in the distribution pattern of osteoblasts and osteoclasts along the bony surface were found between the left control hemimandible and the left and right experimental hemimandibles, which seemed to explain the alterations in mandibular corpus shape between these groups. It was suggested that these changes in the distribution pattern of osteoblasts and osteoclasts were the result of changes in the loading distribution pattern acting upon the mandible, caused by an altered neuromuscular recruitment pattern of the remaining functionally intact, mandibularly attached muscles. The latter was probably the result of adaptive mandibular positioning in response to an altered occlusal relationship, which was induced by the abnormal maxillary growth as a result of the unilateral partial facial paralysis.     

The effect of muscle transplantation after unilateral partial facial paralysis on craniofacial growth and development: relationship between muscle and nerve histomorphometric findings

Muscle transplantation has become an indispensable tool to restore the smile in patients with long-standing or congenital facial paralysis. However, little is known of the effect of this surgical intervention on craniofacial growth and development or of the adaptation of the transplant to its recipient site under circumstances of growth. The present study investigates these phenomena in the rabbit model. Twelve-day-old New Zealand White rabbits were randomly assigned to three experimental groups. The control group was used to study normal craniofacial growth and development (n = 15). In the nerve ablation group, unilateral paralysis of the buccal branches of the facial nerve was surgically induced (n = 15). In the transplant group, the surgically induced unilateral paralysis of the buccal branches was immediately followed by a neuromuscular graft (n = 12). All animals were operated on at the age of 12 days, and follow-up evaluations were performed at the ages of 2 months and 6 months. Computerized dorsoventral roentgencephalometric and computed tomography investigations were performed at both ages. Nerve and muscle histomorphometric measurements were performed at the age of 6 months to relate the quality of nerve and muscle regeneration to the growth parameters. The roentgencephalometric measurements revealed that analogous disturbed parameters were present in the nerve ablation and the transplant groups. However, in the transplant group, an additional significant effect of time between 2 and 6 months was seen for some parameters. This resulted in significant differences between the nerve ablation and transplant groups at 6 months for these parameters. Computed tomography measurements showed no significant differences in maxillary or mandibular volume in the transplant group compared with the control or nerve ablation groups. However, a significantly diminished increase in bone volume existed in the transplant group for the time period between 2 and 6 months in comparison with the control and nerve ablation groups. Muscle histomorphometric findings revealed a significant change in muscle fiber composition in the graft compared with the normal latissimus dorsi muscle; this was due to a major decrease in type IIB fibers, with an increase in type I and type IIA fibers. Compared with the normal zygomaticoauricular muscle, the amount of type I fibers was significantly increased. No fiber atrophy was found. Macroscopically, the transplanted muscle failed to increase its length during growth. Nerve histomorphometric findings demonstrated a normal amount of nerve fibers; however, they had significantly decreased diameters and reduced myelin areas. The nerve histomorphometric parameters were related to the muscle histomorphometric findings, which in turn were related to craniofacial growth disturbances. These findings suggested that the main growth differences between the transplant group and the control group may have been due to altered nerve function influencing muscle function. Scar tissue formation and the development of more intense muscle activity later are suggested as the causes of the additional effect of time between 2 and 6 months for the several parameters in the transplant group. Reasons for the failure of complete conversion of the graft to a fast muscle and the failure of the transplant to elongate during growth are discussed.     

Partial lip resection with orbicularis oris transposition for lower lip correction in unilateral facial paralysis.

Malfunction of the marginal mandibular nerve, either in combination with a generalized facial palsy or in isolation, can cause an unpleasant and disturbing appearance around the mouth. In total palsy, a cross-facial nerve graft combined with a free vascularized muscle transplant will usually deal with this problem successfully; however, all older procedures used in this situation are unpredictable. For the isolated palsy, procedures such as digastric muscle transfer or sling suspension are not uniformly successful. A method using the contralateral, nonaffected lower lip orbicularis muscle is described. A wedge is removed from the paralyzed lower lip and the orbicularis is advanced to the modiolus to provide a functional orbicularis all the way across the lower lip up to the angle of the mouth. This is a simple outpatient procedure that has produced satisfactory results in most cases.     

Motion of the knee after condylar resurfacing--an in vivo study.

The purpose of this study was determine the amounts of rotation and displacement occurring in a relatively unconstrained condylar replacement knee, and to compare the motion with a matched group of normal knees. The motion was measured using an electromagnetic device, the 3-Space Tracker, for various common activities, for 25 normal volunteers and 25 total knee patients. The main variables studied were internal-external rotation of the tibia about its long axis and anterior-posterior displacement of the femoral origin with respect to the tibia, as a function of flexion angle or per cent of gait cycle. The motion of the total knees was very similar to that of the normals. For sitting, standing and free-swing, the knee rotated internally by 5-10 degrees and the femur displaced posteriorly by 9-14 mm, as the knee was flexed from 0 to 90 degrees. For walking and going upstairs and downstairs the absolute values of the rotations and displacements were similar to the above. However, the mean values of rotation were less due to greater variation in the rotation patterns, due probably to the increased laxity of the knee during the swing phases. From these data, taking the mean motions and one standard deviation (S.D.), it is suggested that a knee prosthesis should allow a rotation from minus to plus 12 degrees (a total range of 24 degrees) and an anterior-posterior displacement of 13 mm. It is suggested that these motions be subject to progressive restraint from the neutral position in the manner of the natural knee.     

Synaptic changes in the rabbit amygdala after unilateral lobectomy

Synapse morphology on neurons of the rabbit amygdala was investigated in intact animals and after unilateral lobectomy. The pattern of distribution of synapses normally observed on the neuron surface is altered after disturbance of cortico-amygdalar connections. These changes cannot be entirely explained by degeneration of some afferents. The results support the view that one morphological form of synapse can change into another in the process of function.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 8, No. 2, pp. 134–138, March–April, 1976.     

Trade-off between immunocompetence and growth in magpies: an experimental study

A trade-off between immunity and growth has repeatedly been suggested, mainly based on laboratory and poultry science, but also from experiments where parasitism intensity was manipulated in field bird populations. However, as resource allocation to different activities (or organs) during growth is difficult to manipulate, this trade-off has only been experimentally tested by studying the effects of non-pathogenic antigens. By providing some nestling magpies (Pica pica) with methionine, a sulphur amino acid that specifically enhances T-cell immune response in chickens, we investigated this trade-off by directly affecting allocation of limited resources during growth. Results were in accordance with the hypothetical trade-off because nestlings fed with methionine showed a lower growth rate during the four days of methionine administration, but a larger response when fledglings were challenged with phytohaemagglutinin (a measure of the intensity of T-lymphocyte-mediated immune responsiveness) than control nestlings. Surprisingly, we found that control and experimental nestlings fledged with similar body mass, size and condition, but experimental nestlings suffered less from blood parasites (Haemoproteus) and had fewer lymphocytes (a widely used measure of health status) than control nestlings, suggesting a negative effect of blood parasites or other pathogens on nestling growth.     

Cephalometric study of facial growth in children after combined pushback and pharyngeal flap operations.

Linear and angular cephalometric measurements of children who had had combined palatal pushbacks and superiorly-based pharyngeal flaps do not show later growth retardation of the face. There was an inherent tendency for children with overt clefts of the secondary palate, classic submucous clefts, or occult submucous clefts to demonstrate pre-operatively a narrow SNA and SNB--but the difference between these angles (ANB) was normal.     

A longitudinal study of facial growth in Papio cynocephalus after resection of the cartilagenous nasal septum.

The present study evaluates in Papio cynocephalus the effectiveness of varying the amount of nasal septum resected and the age at surgery in an attempt to develop a technique which may have clinical value for the human condition. The analysis of interdental dimensions by graphical techniques demonstrates that a critical age exists at which total septum resection leads to maximum growth arrest of the premaxilla. Comparisons of linear regression curves for operated and control animals confirm these findings and also demonstrate the existence of sexual dimorphism in premaxillary growth rates.     

Effects of different sex hormones on male rabbit urodynamics: an experimental study

BACKGROUND: The effects of different sex hormones on urodynamics in female rabbits have been investigated previously. Estrogen induces an increase in bladder capacity and compliance, whereas testosterone and progesterone reduced bladder capacity and compliance. OBJECTIVE: The aim of this study was to investigate the effects of sex hormones on bladder urodynamics in male rabbits. METHODS: 5 groups were set up for the study: group I, low midline laparotomy (LML) + 0.9% NaCl; group II, LML + testosterone; group III, LML + bilateral orchiectomy (BO) + testosterone; group IV, LML + BO + progesterone, and group V, LML + BO + estrogen. Baseline urodynamic records and blood sex hormone levels were measured. In the follow-up all rabbits from each group underwent urodynamics 5, 10 and 30 days after injection. Estrogen, progesterone and testosterone levels were also measured during the follow-up period. For statistical verification Mann-Whitney U and Kruskal-Wallis chi(2) tests were used. RESULTS: Hormone levels: Testosterone levels were found to be increased in groups II and III 5 and 10 days after the injection. Testosterone declined thereafter and returned to baseline levels on day 30. In groups IV and V progesterone and estrogen levels increased after the injection and returned to baseline levels on day 30. Urodynamics: In groups II and III testosterone increased the bladder capacity and compliance on days 5 and 10. In these groups, capacity and compliance decreased thereafter and returned to the baseline levels on day 30. These urodynamic findings correlated with the alterations in blood testosterone levels. In groups I and IV no changes were observed in bladder capacity and compliance. In group V capacity and compliance were found to be increased on day 5 after the injection and returned to baseline levels on day 30. The changes in bladder capacity were found to be statistically significant in groups II, III and V. CONCLUSION: In this study, after the injection of testosterone, bladder capacity and compliance increased with high blood testosterone levels in male rabbits. The most interesting finding was observed in the estrogen group, questioning the role of estrogens in males. These findings allow us to reconsider the role of sex hormones in bladder functions.     

Ischemia-reperfusion injury of adipofascial tissue: an experimental study evaluating early histologic and biochemical alterations in rats

Fat necrosis remains a serious complication in reconstructive flaps. In clinical setting, it is well known that fat tissue is more susceptible to ischemic events. We aimed to evaluate early histological and biochemical changes of adipofascial tissue in an experimental model. An epigastric flap model in rats was used to evaluate the effect of ischemia-reperfusion (I-R) injury on adipofascial tissue. Two groups of animals (one with ischemia alone and other ischemia-reperfusion group) were used to evaluate the degree of histological edema, congestion and extravascular bleeding, and early biochemical alterations within the adipofascial flaps. The biochemical parameters included glutathione (GSH) and malondialdehyde (MDA). In each group, contralateral groin subcutaneous adipose tissue served as control. These evaluations were compared to normal unmanipulated, contralateral abdominal subcutaneous adipose tissue. The ischemia-reperfused flap group showed histologically significantly much edema congestion and bleeding than the control groups (P<.0001). The control group showed less edema in fat tissue than the ischemia-alone group (P<.05). All of the flaps in the ischemia-only group showed significantly less bleeding and edema than I-R group (P<.001). The ratio of MDA/GSH was 33 in control, 37 in ischemia alone, and 82 in ischemia-reperfusion groups, respectively. This study confirms that significant histologic and biochemical alteration occurs after ischemia and ischemia-reperfusion events in adipose tissue. Marked drop in adipose tissue antioxidant levels after I-R suggested that preemptive measures to this decrease should be undertaken in clinical settings.     

Resprouting after disturbance: an experimental study with short-lived monocarpic herbs

We experimentally demonstrated the ability of three short-lived monocarpic species to vegetatively regenerate (resprout) from roots after severe disturbance. We assessed the relationship between resprouting ability and (1) timing of injury with respect to life-cycle stage (reproductive vs. vegetative plant), life-history mode (annual vs. winter annual) and phenological stage (flowering vs. fruiting plant), (2) nutrient availability, and (3) disturbance severity (removal of all axillary buds Yes/No). In a chamber experiment with the annual or potentially winter annualRorippa palustris, all injured plants resprouted in all nutrient levels and day-length regimes (day-length regimes simulated conditions of an annual and a winter annual cohort). The number of adventitious buds on roots was positively affected only by injury. The extent of regeneration and amount of regenerated biomass were higher at high nutrient level and long-day regime.