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The biomechanics problems of thinwalled brain veins
Hemza, Jan ; Maršík, František (advisor) ; Otáhal, Jakub (referee) ; Vašků, Anna (referee)
Biomechanical material properties of the bridging brain veins are investigated experimentally (A Nikon light microscope was used for the histo-anatomical study and viskoelastic properties was measured on a MTS 858.2 Mini Bionix system ) and theoretically. The main goal of the developed theory was to formulate the biomechanical conditions (geometrical dimensions, viscoelastic properties of veins and blood fluid flow conditions) at which unstable behavior or even vein collapse can occur. The study of the geometry and topology of bridging veins was carried out by a magnetic resonance (Siemens Magnetom Symphony1,5 T) and a stereomicroscope (Nikon SMZ 1500) complemented with a digital camera (Nikon Coolpix E995) and Lucia Net software. From the biomechanical point of view, experimental findings can be summarized as follows: the existence of two types of venous brain systems; thin and thick wall veins with a one order difference in elastic modulus magnitude high sensitivity of the thin wall veins on the blood flow rate and extension or contraction on their structural stability the existence of continuing small wall vibration under physiological conditions Under small deformations conditions, the shear modulus was shown experimentally to be in the range (2÷4)·10 4 Pa with a Young modulus E= (0.6÷1.2)·10 5...
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Role some genetic factors in bodyweight changes
Aldhoon, Bashar ; Hainer, Vojtěch (advisor) ; Kohoutová, Milada (referee) ; Vašků, Anna (referee)
The aim of the study was to determine the role of certain genetic factors on the ability to maintain weight loss, as well as to reduce the health risks associated with obesity in a group of about 300 obese patients followed for 2.5 years. The first part dealt with monitoring the impact of P73T polymorphism of the neuromedin gene on body weight reduction and its relation to certain metabolic and psychobehavioral factors. In the group of obese men, T allele non-carriers achieved significant reduction in waist circumference at the end of the follow-up. This waist circumference reduction was accompanied by a significant reduction in energy intake and by a significant decrease in the Beck depression score, while dietary restraint score increased. In the group of obese women, no significant differences between carriers and non-carriers of the T allele were observed. The significant reduction in total energy intake and macronutrient consumption was achieved in obese women regardless the genotype. In the second part, the effect of the Leu162Val of PPAR and Pro12Ala of PPAR gene polymorphisms on body weight reduction and on metabolic and psychobehavioral factors was studied in a group of 246 obese women. At baseline, non-carriers compared to carriers of the minor Val-allele of PPAR gene exhibitied a favorable effect...
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The biomechanics problems of thinwalled brain veins
Hemza, Jan ; Maršík, František (advisor) ; Otáhal, Jakub (referee) ; Vašků, Anna (referee)
Biomechanical material properties of the bridging brain veins are investigated experimentally (A Nikon light microscope was used for the histo-anatomical study and viskoelastic properties was measured on a MTS 858.2 Mini Bionix system ) and theoretically. The main goal of the developed theory was to formulate the biomechanical conditions (geometrical dimensions, viscoelastic properties of veins and blood fluid flow conditions) at which unstable behavior or even vein collapse can occur. The study of the geometry and topology of bridging veins was carried out by a magnetic resonance (Siemens Magnetom Symphony1,5 T) and a stereomicroscope (Nikon SMZ 1500) complemented with a digital camera (Nikon Coolpix E995) and Lucia Net software. From the biomechanical point of view, experimental findings can be summarized as follows: the existence of two types of venous brain systems; thin and thick wall veins with a one order difference in elastic modulus magnitude high sensitivity of the thin wall veins on the blood flow rate and extension or contraction on their structural stability the existence of continuing small wall vibration under physiological conditions Under small deformations conditions, the shear modulus was shown experimentally to be in the range (2÷4)·10 4 Pa with a Young modulus E= (0.6÷1.2)·10 5...
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Role some genetic factors in bodyweight changes
Aldhoon, Bashar ; Hainer, Vojtěch (advisor) ; Kohoutová, Milada (referee) ; Vašků, Anna (referee)
The aim of the study was to determine the role of certain genetic factors on the ability to maintain weight loss, as well as to reduce the health risks associated with obesity in a group of about 300 obese patients followed for 2.5 years. The first part dealt with monitoring the impact of P73T polymorphism of the neuromedin gene on body weight reduction and its relation to certain metabolic and psychobehavioral factors. In the group of obese men, T allele non-carriers achieved significant reduction in waist circumference at the end of the follow-up. This waist circumference reduction was accompanied by a significant reduction in energy intake and by a significant decrease in the Beck depression score, while dietary restraint score increased. In the group of obese women, no significant differences between carriers and non-carriers of the T allele were observed. The significant reduction in total energy intake and macronutrient consumption was achieved in obese women regardless the genotype. In the second part, the effect of the Leu162Val of PPAR and Pro12Ala of PPAR gene polymorphisms on body weight reduction and on metabolic and psychobehavioral factors was studied in a group of 246 obese women. At baseline, non-carriers compared to carriers of the minor Val-allele of PPAR gene exhibitied a favorable effect...
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