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FUNCTIONAL AND MOLECULAR STUDY OF HUMAN MASSETER FIBERS

人体咬肌纤维的功能和分子研究

基本信息

批准号：
6176944
负责人：
JAMES J SCIOTE
金额：
$ 10.47万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
1996
资助国家：
美国
起止时间：
1996-04-01 至 2003-03-31
项目状态：
已结题

项目摘要

DESCRIPTION (Adapted from the Applicant's Abstract): Mammalian skeletal muscle fibers have been traditionally classified into specific types by characterization of their myofibrillar ATPase and metabolic histochemistry and more recently by immunohistochemistry with myosin heavy chain (MHC)-specific antibodies. Human skeletal muscle contains three main fiber types: I, IIA and IIX (or IIB) derived from specific MHC isoforms. Mammalian jaw-closing muscle fibers are notably different in comparison to other skeletal muscle, reflecting the specialized nature of their functions. The jaw-closing muscle fibers of the human primate are the most exceptional, expressing developmental and cardiac MHC and myosin light chain (MLC) isoforms not found in other adult skeletal muscle, as well as the typical adult skeletal isoforms. A full description of myosin expression in human masseter is presently incomplete, and a fiber type classification scheme, incorporating both myosin protein content and contractile function, is lacking. Using human masseter muscle biopsies, the first specific aim of this study is to develop a fiber type classification scheme for jaw-closing muscles based on MHC and MLC identification as determined by tissue staining for: myofibrillar ATPase and metabolic histochemistry, immunohistochemistry with MHC-specific antibodies and in situ hybridization with probes developed from different MHC gene transcripts. In whole muscle biopsies and in single fibers, MHC content will be confirmed by glycerol-SDS- PAGE, and MLC content by 2-D electrophoresis. In addition, electron microscopy will be used to evaluate the relative heterogeneous distribution of myosin isoforms within representative fibers. The second aim of this study is to determine the maximum speed of unloaded shortening (Vo), as determined by the slack test, and specific tension (Po) of the individual chemically skinned or freeze-dried fibers representative of each fiber type. Following physiology, the relative percent content of MHC and MLC isoforms in these single fibers will also be correlated to Vo and Po to determine if these physiologic parameters are related to contractile protein expression as is the case in other human skeletal muscle. The long-term objectives of this work are to provide detailed, basic information regarding the exceedingly complex contractile protein expression in human jaw-closing muscle, the classification of specific fiber types distinct or similar to other skeletal muscle, and the main physiological properties of each fiber type. This information may serve as a basis from which dentistry may apply a more thorough understanding of jaw-closing muscle function to common clinical problems such as temporomandibular joint disorders, abnormal craniofacial growth and stability after orthognathic surgical procedures.

描述（改编自申请人摘要）：哺乳动物骨骼肌纤维传统上被分为特定类型，其肌原纤维ATP酶和代谢的特征组织化学和最近的肌球蛋白免疫组织化学重链（MHC）特异性抗体。人体骨骼肌含有三种主要的纤维类型：I，IIA和IIX（或IIB），来自特定的 MHC同种型。哺乳动物的下颌闭合肌纤维明显不同与其他骨骼肌相比，他们的功能。人类灵长类动物的下颌闭合肌纤维是最特殊的，表达发育和心脏MHC，肌球蛋白轻链（MLC）亚型在其他成人骨骼肌中未发现肌肉，以及典型的成人骨骼亚型。全肌球蛋白在人咬肌中表达的描述目前是不完整的，和纤维类型分类计划，包括两个肌球蛋白含量和收缩功能缺乏。使用人咬肌活检，本研究的第一个具体目的是，开发一个纤维类型分类方案，用于下颌闭合肌，通过组织染色确定的MHC和MLC鉴定：肌原纤维ATP酶和代谢组织化学，免疫组织化学用MHC特异性抗体和探针原位杂交由不同的MHC基因转录本进化而来。在整个肌肉活检中在单根纤维中，MHC含量将通过甘油-SDS-聚丙烯酰胺凝胶电泳（SDS-PAGE）进行确认。双向电泳测定MLC含量。此外，电子显微镜将用于评价相对异质性肌球蛋白亚型在代表性纤维中的分布。第二这项研究的目的是确定最大速度卸载通过松弛试验确定的缩短率（Vo）和比张力 (Po)化学剥皮或冷冻干燥的纤维代表每种纤维类型。根据生理学，相对这些单纤维中MHC和MLC同种型的百分比含量也将与Vo和Po相关，以确定这些生理参数是否与收缩蛋白表达有关，人体骨骼肌这项工作的长期目标是提供有关极其复杂的收缩蛋白在人下颌闭合肌中的表达特殊纤维类型的分类骨骼肌，以及每种纤维的主要生理特性类型.这些信息可以作为牙科学的基础，将对下颌闭合肌肉功能的更深入了解应用于常见的临床问题如颞下颌关节紊乱，正颌外科术后颅面生长和稳定性异常程序.