EFFECT OF GROWTH HORMONE ON CRANIOFACIAL PROPORTIONS

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This research investigates the effects of variation in growth hormone (GH) on facial growth,dental size and development, and occlusion. Craniofacial proportion changes, localized patterns of bone deposition and resorption, and tooth size, shape, development and occlusion will be examined in three primary models of endocrine growth disturbance: 1) giant transgenic (MTrGH) mice; 2) Snell dwarf (dw/dw) mutant mice; and 3) GH-administered marmoset monkeys. Generally stated, the hypothesis to be tested in this work is that in all three experimental groups changes in the size and shape of the craniofacial complex will result from differential extension (in the transgenic mice, marmosets) or truncation (in the dwarf mice) of the patterns of allometric (relative) growth observed in the respective control groups. In addition, differences in craniofacial proportions between experimentals and controls are hypothesized to result from differences in general rates of bone resorption and deposition, as opposed to fundamental shifts in these basic regional patterns themselves, and the size, shape and patterns of eruption and occlusion of the teeth are hypothesized to be similar in both experimental and control groups. These hypotheses will be tested by utilizing linear dimensions and coordinate points taken from skulls and radiographs. Scanning electron microscopic examination of bone surfaces will determine the distribution of patterns of resorption and deposition during growth. My career objectives are to continue my preliminary studies of the influence of growth hormones on patterns of skeletal growth and proportions, and to extend these more fully into the experimental and clinical realms. An RCDA would particularly advance my research career by dramatically reducing my unusually heavy teaching load which is an obstacle to the effective implementation of involved and prolonged laboratory and clinical investigations. Moreover, this award would allow me to develop new research directions in my investigations of skeletal growth and proportions, particularly longitudinal and experimental studies of growth hormone administration in a primate model, and the use of SEM analysis in the determination of patterns of bone deposition and resorption in the craniofacial complex during normal and abnormal growth. The Institution's support plans if an RCDA is awarded include a reduction of my normal teaching load by more than half, such that total time allotted for the research described would be 80% with no more than 20% of my time spent on related teaching and advising activities. In addition, access to specific research resources including equipment as well as training in growth hormone (GH) administration experiments and the determination of growth hormone levels will be provided by my home departments and others here at Northwestern.