A number of investigators have determined the joint forces acting at the hip and knee for normal human locomotion as related to the design of prosthetic devices. This research has been extended to allow the calculation or estimation of the muscular and ligamentous forces operating at the knee joint for normal walking. The current study expanded upon the past research to evaluate the magnitude and temporal sequence of.the muscle, ligament and articular forces acting at the knee joint for a simulated skating thrust. A skilled ice hockey player was filmed in two reference planes while making a skating thrust from a laboratory force platform. The cine film data was synchronized with the force plate output to allow calculation of the orthogonal forces and moments imposed on the knee joint. The orthogonal force system was determined from a knowledge of the inertial, gravitational and reaction forces acting on the lower limb during the skating thrust. The muscle, ligament and joint forces were determined from equations derived from the conditions of joint equilibrium. The equations of equilibrium were indeterminate and had to be reduced by making assumptions from electromyographic records to allow solution. Forces were calculated for a simplified muscle and ligament system which included the hamstrings, quadriceps and gastrocnemius muscle groups, the collateral ligaments and the cruciate ligaments of the knee joint. In addition, the articular joint force, joint torque and centre of pressure of the joint force were determined. Results of the investigation revealed that the magnitude of the muscle, ligament and joint forces developed in a skating thrust were considerably greater than respective forces exerted during level walking while the temporal sequence of the skating forces was comparable to walking upstairs. The quadriceps muscle group exerted the greatest contractile force while the gastrocnemius and hamstrings groups developed much smaller forces. The largest ligament forces were developed in the collateral ligaments and the posterior cruciate ligament to maintain stability of the joint. The knee joint is subject to the combined effects of a joint force six times body weight and a large joint torque superimposed upon each other during the skating thrust and this fact is considered important when discussing the cause of menisci knee injuries. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

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<p>Smooth muscle cells from pig aortic media were grown in tissue culture, in medium containing 10% calf serum. Lipid biosynthesis from radioactive substrates 1-¹⁴C-acetate, U-¹⁴C-D-glucose, 1-¹⁴C-oleic acid and ³²P-phosphoric acid was measured. In addition, the influence of various sera, including pig serum, normolipemic human serum (NLHS), and hyperlipemic human serum (HLHS) on lipid biosynthesis from acetate and phosphoric acid was studied</p> <p>Compared to calf serum, all three test sera caused a stimulation of lipid synthesis in the lipid classes, phospholipid (PL), free fatty acids (FFA), triglycerides (TG) and cholesterol esters (CE), and an inhibition of cholesterol plus diglyceride (S + DG) synthesis. The extent of stimulation was least for pig serum and greatest for HLHS; the inhibition of S + DG was greatest for HLHS and least for pig serum. It was noted that the HLHS stimulation of CE synthesis was proportionately greater than the stimulation of the other lipid classes and that the HLHS inhibition of S + DG was significantly greater than that seen with the other test sera.</p> <p>The morphology of cultured aortic smooth muscle cells grown in 10% calf serum and 10% HLHS was examined by means of scanning and transmission electronmicroscopy. It was observed that HLHS caused degenerative alterations in the morphology of the cultured smooth muscle cells, such as an abundance of lipid droplets and cellular debris. The implications of these results in relation to the development of atherosclerosis are discussed.</p> / Thesis / Master of Science (MS)

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Over 2.4 million eye injuries occur each year in the United States as a result of trauma. Eye injuries have been investigated for years; however, the role of the extraocular muscles in relation to eye injuries has yet to be quantified. In this research, Computed Tomography quasi-static tests were conducted to investigate the effect of the presence of the extraocular muscles on the biomechanical response of the human eye in situ. Three matched pairs of human eyes were displaced in 5 mm increments using a large flat cylindrical indenter to a maximum displacement of 30 mm. The loading was similar to what is experienced during a blunt impact, which is believed to cause the most serious eye injuries. In the matched pair, one eye had the extraocular muscles intact and the other had the extraocular muscles transected. Force, pressure, and displacement measurements were collected for each test. A trend was seen where a greater amount of force was created in the eye with the extraocular muscles intact than in the eye with the muscles transected, and a correlation between them was made. The greatest force measured in an eye with the extraocular muscles intact was 92 N, while the greatest force measured in an eye with the extraocular muscles transected was 80 N. An increase in intraocular pressure was also noticed for an eye with the extraocular muscles attached, rising steadily from 2 kPa to a maximum pressure of just over 50 kPa. It was also noted that during a quasi-static impact the eye can move out of the way of the imposing force. Since the test data set was small, analytical calculations were also conducted. / Master of Science

Titre de l'écran-titre (visionné le 26 avril 2023) / Les myopathies des muscles pectoraux (MMP) sont des conséquences inattendues de la sélection génétique visant à augmenter le rendement en poitrine chez le poulet de chair. Elles se manifestent sous forme de stries blanches à la surface du filet (les striations blanches), par une dureté prononcée du muscle (le durcissement de la poitrine) ou par la désintégration de la structure musculaire (la déstructuration du filet). Au Québec, très peu est connu sur la présence et l'impact de ces myopathies sur les qualités de la viande de poulet. Pour pallier ce manque de données, un total de 206 filets ont été échantillonnés dans sept marchés d'alimentation québécois et évalués pour la présence des MMP et leurs effets sur la qualité. Les résultats ont démontré que 48,5 % des filets évalués étaient myopathiques et que les filets commercialisés de format économique (ECO), commercial (COM) ou de haut de gamme (SUPQ), étaient tous d'égale susceptibilité au développement de MMP (P > 0,05). En outre, 19,4 % des filets évalués étaient pâles, mous et exsudatifs (PSE-Like, pH ≤ 5,7) alors que 6,8 % de ces filets étaient de couleur foncée, avaient une texture dure et un aspect extérieur sec (DFD, pH ≥ 6,1). L'effet combiné des MMP et des DFD s'est traduit par une augmentation significative des comptes de salmonelles (P < 0,001), d'entérobactéries (P < 0,01) et des aérobes mésophiles totaux (P < 0,01) comparativement aux filets normaux. Par ailleurs, les MMP ont engendré une augmentation de la teneur des filets en lipides (P < 0,0001) et une tendance à la diminution de leur teneur en protéines (P = 0,07). En conclusion, cette étude confirme pour la première fois la présence des MMP au Québec et fournit des données originales sur leurs conséquences à la fois pour le consommateur et pour l'industrie de transformation. / Breast muscle myopathies (BMM) are unintended consequences of genetic selection aimed at increasing breast meat yield in broiler chickens. They appear as white striations on the surface of the breast fillets (White striping), as a pronounced hardness of the Pectoralis major muscle (Wooden or Woody breast) or as a severe structural disintegration of this muscle (Spaghetti meat syndrome). In Quebec, very little is known about the presence and impact of these myopathies on the qualities of broiler breast meat. To bridge this gap, a total of 206 fillets were sampled from seven grocery stores located in different regions of the province. They were then evaluated for the presence of BMM, and then analyzed to investigate the effects of BMM on their quality. The results showed that 48.5% of the evaluated fillets were myopathic and that the fillets marketed under economic (ECO), commercial (COM) or high quality (SUPQ) brands were all equally susceptible to the development of BMM (P > 0.05). In addition, 19.4% of the fillets evaluated were pale, soft and exudative (PSE-Like, pH ≤ 5.7) while 6.8% of these fillets were dark, firm and dry (DFD, pH ≥ 6.1). The combined effect of BMM and DFD resulted in a significant increase in the microbial counts of Salmonella (P < 0.001), Enterobacteriaceae (P < 0.01) and Total Mesophilic Aerobes (P < 0.01) compared to normal breast fillets. Furthermore, BMM were associated with an increase in the lipid content of breast fillets (P < 0.0001) and a tendency of their protein content to decrease (P = 0.07) leading to the deterioration of their nutritional quality. In conclusion, this study confirmed for the first time the presence of BMM in Quebec and provided original data on their consequences for both the consumer and the processing industry.