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Cephalometric studies of the mandible, its masticatory muscles and vasculature of growing Gottingen Minipigs-A comparative anatomical study to refine experimental mandibular surgery.

ABSTRACT: Over many decades, the Göttingen Minipig has been used as a large animal model in experimental surgical research of the mandible. Recently several authors have raised concerns over the use of the Göttingen Minipig in this research area, observing problems with post-operative wound healing and loosening implants. To reduce these complications during and after surgery and to improve animal welfare in mandibular surgery research, the present study elucidated how comparable the mandible of minipigs is to that of humans and whether these complications could be caused by specific anatomical characteristics of the minipigs' mandible, its masticatory muscles and associated vasculature. Twenty-two mandibular cephalometric parameters were measured on CT scans of Göttingen Minipigs aged between 12 and 21 months. Ultimately, we compared this data with human data reported in the scientific literature. In addition, image segmentation was used to determine the masticatory muscle morphology and the configuration of the mandibular blood vessels. Compared to data of humans, significant differences in the mandibular anatomy of minipigs were found. Of the 22 parameters measured only four were found to be highly comparable, whilst the others were not. The 3D examinations of the minipigs vasculature showed a very prominent deep facial vein directly medial to the mandibular ramus and potentially interfering with the sectional plane of mandibular distraction osteogenesis. Damage to this vessel could result in inaccessible bleeding. The findings of this study suggest that Göttingen Minipigs are not ideal animal models for experimental mandibular surgery research. Nevertheless if these minipigs are used the authors recommend that radiographic techniques, such as computed tomography, be used in the specific planning procedures for the mandibular surgical experiments. In addition, it is advisable to choose suitable age groups and customize implants based on the mandibular dimensions reported in this study.

SUBMITTER: Corte GM

PROVIDER: S-EPMC6483209 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Project description:Masticatory muscle activity during teeth clenching is associated with changes in many physiological parameters throughout the body. Clenching can improve muscle activity, force production, rate of force development, and joint fixation. Hence, teeth clenching and masticatory muscle activity can be important in competitive sports activities. Sport climbing is becoming increasingly popular and will be included for the first time in the Summer Olympic Games, Tokyo, 2020. However, masticatory muscle activity in sport climbers has not yet been studied. The aim of the presented study is to compare the bioelectrical activity of the masticatory muscles in sport climbers and non-climbers in order to determine the relationship between these muscles and climbing activity. 44 subjects without masticatory system disorders (16 women and 28 men, average age 26.3) were divided into two groups of 22 sport climbers (8 women, 14 men, climbing experience >4 years), while 22 people (8 women, 14 men, with no regular sports activity) were assigned to the control group. Electromyographic examination of temporalis anterior (TA) and masseter muscle (MM) was evaluated in three conditions: during resting mandibular position, during maximum intercuspation clenching, and during maximum voluntary clenching with cotton rolls between teeth. For statistical analysis, the W Shapiro-Wilk test and the Mann-Whitney U test were used. Sport climbers showed significantly higher bioelectrical activities of MM during maximum intercuspation clenching (238.45 ?V vs. 83.87 ?V, p = 0.002), and during maximum voluntary clenching with cotton rolls between teeth (300.01 ?V vs. 101.38 ?V, p = 0.001) compared to controls. The differences between groups in relation to the resting bioelectrical activity of the MM muscles, and TA muscles in all conditions were not statistically significant (p > 0.05). Higher bioelectrical activity of masseter muscles during clenching in climbers can be associated with this sports activity. However, the mechanism remains unknown and requires future research.

Project description:ObjectiveThe worldwide prevalence of obesity has increased to 10% in men and 15% in women and is associated with severe comorbidities such as diabetes, cancer, and cardiovascular disease. Animal models of obesity are central to experimental studies of disease mechanisms and therapeutic strategies. Diet-induced obesity (DIO) models in rodents have provided important insights into the pathophysiology of obesity and, in most instances, are the first in line for exploratory pharmacology studies. To deepen the relevance towards translation to human patients, we established a corresponding DIO model in Göttingen minipigs (GM).MethodsYoung adult female ovariectomized GM were fed a high-fat/high-energy diet for a period of 70 weeks. The ration was calculated to meet the requirements and maintain body weight (BW) of lean adult minipigs (L-GM group) or increased stepwise to achieve an obese state (DIO-GM group). Body composition, blood parameters and intravenous glucose tolerance were determined at regular intervals. A pilot chronic treatment trial with a GLP1 receptor agonist was conducted in DIO-GM. At the end of the study, the animals were necropsied and a biobank of selected tissues was established.ResultsDIO-GM developed severe subcutaneous and visceral adiposity (body fat >50% of body mass vs. 22% in L-GM), increased plasma cholesterol, triglyceride, and free fatty acid levels, insulin resistance (HOMA-IR >5 vs. 2 in L-GM), impaired glucose tolerance and increased heart rate when resting and active. However, fasting glucose concentrations stayed within normal range throughout the study. Treatment with a long-acting GLP1 receptor agonist revealed substantial reduction of food intake and body weight within four weeks, with increased drug sensitivity relative to observations in other DIO animal models. Extensive adipose tissue inflammation and adipocyte necrosis was observed in visceral, but not subcutaneous, adipose tissue of DIO-GM.ConclusionsThe Munich DIO-GM model resembles hallmarks of the human metabolic syndrome with extensive adipose tissue inflammation and adipocyte necrosis reported for the first time. DIO-GM may be used for evaluating novel treatments of obesity and associated comorbidities. They may help to identify triggers and mechanisms of fat tissue inflammation and mechanisms preventing complete metabolic decompensation despite morbid obesity.

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Cephalometric studies of the mandible, its masticatory muscles and vasculature of growing Gottingen Minipigs-A comparative anatomical study to refine experimental mandibular surgery.

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