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Genetic and Hormonal Regulation of Children's Growth MUDr. Jan Vosáhlo Abstract Growth in childhood is a complex process of changing the body, which can be disrupted by various illnesses including endocrine disorders, particularly growth hormone deficiency. Tumors or other processes affecting hypothalamic-pituitary area can be a postnatal cause of GHD; prenatal causes include 1) developmental disorders of the pituitary as part of complex syndromes, 2) developmental disorders of the pituitary due to defects in regulatory genes and 3) defects in genes involved in the synthesis and secretion of GH. The first topic of the thesis was septo-optic dysplasia - a complex syndrome involving optic nerve hypoplasia, structural brain abnormalities and pituitary dysfunctions. We extensively described phenotype in 11 Czech patients; we observed both complete SOD and incomplete forms variously combining two of the three main components of the syndrome. The cohort then became a part of an international study of 68 patients, in which we studied the phenotype in dependence on the brain morphology. We found correlation between the severity of clinical symptoms and the degree of septum pellucidum abnormities and also a correlation between hippocampus and falx abnormities and neurological symptoms. As the second topic we studied...

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Biomechanical factors influencing the reduction of dislocated hips with the Pavlik harness in patients of Developmental Dysplasia of the Hip (DDH) were studied using a simplified three-dimensional computer model simulating hip reduction dynamics in (1) subluxated, and (2) fully dislocated hip joints. The CT-scans of a 6 month-old female infant were used to measure the geometrical features of the hip joint including acetabular and femoral head diameter, acetabular depth, and geometry of the acetabular labrum, using the medical segmentation software Mimics. The lower extremity was modeled by three segments: thigh, leg, and foot. The mass and the location of the center of gravity of each segment were calculated using anthropometry, based on the total body mass of a 6-month old female infant at the 50th length-for-age percentile. A calibrated nonlinear stress-strain model was used to simulate muscle responses. The simplified 3D model consists of the pubis, ischium, acetabulum with labrum, and femoral head, neck, and shaft. It is capable of simulating dislocated as well as reduced hips in abduction and flexion. Five hip adductor muscles were identified as key mediators of DDH prognosis, and the non-dimensional force contribution of each in the direction necessary to achieve concentric hip reductions was determined. Results point to the adductor muscles as mediators of subluxated hip reductions, as their mechanical action is a function of the degree of hip dislocation. For subluxated hips in abduction and flexion, the Pectineus, Adductor Brevis, Adductor Longus, and proximal Adductor Magnus muscles contribute positively to reduction, while the rest of the Adductor Magnus contributes negatively. In full dislocations all muscles contribute detrimentally to reduction, elucidating the need for traction to reduce Graf IV type dislocations. Reduction of iv dysplastic hips was found to occur in two distinct phases: (a) release phase and (b) reduction phase. To expand the range of DDH-related problems that can be studied, an improved threedimensional anatomical computer model was generated by combining CT-scan and muscle positional data belonging to four human subjects. This model consists of the hip bone and femora of a 10-week old female infant. It was segmented to encompass the distinct cartilaginous regions of infant anatomy, as well as the different regions of cortical and cancellous bone; these properties were retrieved from the literature. This engineering computer model of an infant anatomy is being employed for (1) the development of a complete finite element and dynamics computer model for simulations of hip dysplasia reductions using novel treatment approaches, (2) the determination of a path of least resistance in reductions of hip dysplasia based on a minimum potential energy approach, (3) the study of the mechanics of hyperflexion of the hip as alternative treatment for late-presenting cases of hip dysplasia, and (4) a comprehensive investigation of the effects of femoral anteversion angle (AV) variations in reductions of hip dysplasia. This thesis thus reports on an interdisciplinary effort between orthopedic surgeons and mechanical engineers to apply engineering fundamentals to solve medical problems. The results of this research are clinically relevant in pediatric orthopaedics.

Профилактика внезапной сердечной смерти спорте является актуальной задачей, решение которой способно значительно улучшить показатели продолжительности и качества жизни спортсменов. Проблема состоит в отсутствии рекомендаций по планированию тренировочного процесса и профилактике возникновения угрожающих жизни состояний при занятиях спортом у лиц с синдромом дисплазии соединительно ткани. Цель исследования – повышение адаптивных возможностей организма и профилактику осложнений у молодых спортсменов с дисплазией соединительной ткани. В соответствии с целью была выдвинута гипотеза, что рациональное дозирование физических нагрузок в ходе тренировочного процесса, с учетом индивидуальных особенностей организма, у молодых спортсменов с синдромом дисплазии соединительной ткани позволит улучшить адаптацию к физическим нагрузкам, а также снизить риск развития осложнений дисплазии соединительной ткани, в том числе внезапной сердечной смерти. / Prevention of sudden cardiac death in sports is an urgent problem of the modern society. It is critically important to improve life expectancies and quality of life of competitive athletes. The main issue is the absence of recommendations for exercise prescription and training schedule in terms of connective tissue dysplasia syndrome. The purpose of the study was to increase the adaptation abilities of an organism and prevention of possible health complications in young athletes with connective tissue dysplasia. It was hypothesized that rational physical loads dozing in accordance to individual capacity of these individuals will result in better adaptation to exercise loads and decrease of the possible risks, including sudden cardiac death.

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