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A presentation on Arterial System of brain, Neurosurgery King Edward Medical University / Mayo Hospital Lahore Webinar Series.

In this study, we propose an electrical circuit model that will be useful for understanding of the mechanisms and dynamics of the human cardiovascular system, which is considered as a complex system in the field of physiology. The electrical circuit model, defined as the Windkessel model, plays an important role in the observation of the characteristic effect of the blood pressure on the arterial system. An electrical circuit model, which we have connected to the input terminals of the Windkessel model, ensures that the mean arterial blood pressure signals are observed within the expected range of values. The Windkessel circuit model that we have tried to develop in this study was constructed in a laboratory environment and the results were observed. It is thought that this study will contribute to the literature in terms of the development of the Windkessel model by increasing the number of parameters involved in the models of heart and arterial system., Bu çalışmada, fizyoloji alanında karmaşık bir sistem olarak kabul edilen insan kardiyovasküler sistemin sahip olduğu mekanizmaların ve dinamiklerinin anlaşılabilmesine fayda sağlayacak elektriksel bir devre modeli önerilmektedir. Windkessel model olarak tanımlanan elektriksel devre modeli, kalpten pompalanan kan basıncının arteriyel sistemdeki karakteristik etkisinin gözlemlenmesinde önemli rol oynamaktadır. Windkessel modelin girişine entegre ettiğimiz ayrı bir elektrik devre modeli, ortalama arteriyel kan basıncı sinyallerinin beklenen değer aralıklarında gözlemlenmesini sağlamaktadır. Bu çalışmada ele alınan ve geliştirmeye çalıştığımız Windkessel devre modeli laboratuvar ortamında kurulumu gerçekleştirilmiş ve sonuçları gözlemlenmiştir. Kalp ve arteriyel sistem ilişkisinde rol alan parametre sayılarının arttırılarak, Windkessel modelin geliştirilmesine bir alt yapı olması açısından bu çalışmanın literatüre katkı sağlayacağı düşünülmektedir.

Background Despite pronounced increases in central pulse wave velocity ( PWV ) with aging, reflected wave transit time ( RWTT ), traditionally defined as the timing of the inflection point ( T INF ) in the central pressure waveform, does not appreciably decrease, leading to the controversial proposition of a “distal‐shift” of reflection sites. T INF , however, is exceptionally prone to measurement error and is also affected by ejection pattern and not only by wave reflection. We assessed whether RWTT , assessed by advanced pressure‐flow analysis, demonstrates the expected decline with aging. Methods and Results We studied a sample of unselected adults without cardiovascular disease (n=48; median age 48 years) and a clinical population of older adults with suspected/established cardiovascular disease (n=164; 61 years). We measured central pressure and flow with carotid tonometry and phase‐contrast MRI , respectively. We assessed RWTT using wave‐separation analysis ( RWTT WSA ) and partially distributed tube‐load (TL) modeling ( RWTT TL ). Consistent with previous reports, T INF did not appreciably decrease with age despite pronounced increases in PWV in both populations. However, aging was associated with pronounced decreases in RWTT WSA (general population −15.0 ms/decade, P P =0.003) and RWTT TL (general −15.8 ms/decade, P P T INF was shown to reliably represent RWTT only under highly unrealistic assumptions about input impedance. Conclusions RWTT declines with age in parallel with increased PWV , with earlier effects of wave reflections and without a distal shift in reflecting sites. These findings have important implications for our understanding of the role of wave reflections with aging.

In 1997 West, Brown & Enquist published a theoretical explanation for the long-known empirical observation of 3/4-power scaling of organismal metabolic rates with body mass, using an attractive combination of general physical and physiological principles with evolutionary optimization. This model generated hundreds of studies, exploring its implications for physiology, populations, biodiversity, whole-ecosystem functioning, and even medical, engineering and social sciences.However, the evolutionary optimization part of the model has never been carefully scrutinized.In this article we perform the evolutionary optimization as proposed by the authors rigorously and show that it actually leads to a biologically irrelevant network, i.e. a single vessel.Moreover, we find that by relaxing some assumptions in a realistic way we obtain a feasible network but with isometric scaling of metabolism, which is in conflict with Kleiber's empirical law of an allometric exponent of around 3/4.Hence, we conclude that the West-Brown-Enquist model cannot account for the observed universal metabolic scaling relation.As possible solutions to this paradox, we discuss (weak) body-size dependence of capillary properties (leading to different predictions of intra- and inter-specific metabolic scaling), and expanding the West-Brown-Enquist model to an integrated network model (including body shape and oxygen transport to and from the arterial system). Alternatively, the ultimate explanation for the observed allometric patterns may need to be found outside the framework of flow-limited network theory.We conclude that Kleiber's law is still as theoretically unexplained as ecologically important.

INTRODUCTION: Knowledge of the frequency of anatomical variations of arterial pattern of hand is crucial for safe and successful hand surgical approach, diagnostic and therapeutic procedures. The superficial pal mar arch is a major blood supply to the hand. Various ano malous patterns in the superficial arch of hand are reported. The superficial pal mar arch is formed predominantly by ulnar artery with a contribution from superficial branch of radial artery. OBSERVATIONS: Superficial palmar arch is dissected within the p alm and observed from its origin to termination. Variations in its origin, branches were observed. A classic superficial palmar arch was found in 10% [5/50]. O ut of dissected specimens complete arch found in 67% and incomplete arch was 33%. Incomplete arch is formed by ulnar artery alone. It supply four and half fingers and give five branches. Majority of arches is supplied by three and half fingers and gives four branches. DISCUSSION: Many attempts have been made to classify these variations. A complex cla ssification of superficial pal mar arch by Coleman & Anson [1961]. S ince then, many other classification have been suggested by different authors [Karlsson & N iechajev, 1982; al - Turk & Metcalf, 1984; Doscher et al. 1985; Ruengsakulrachh et al. 2001;] provi des simplest understanding of distribution of the arches. Although the classical pattern of the arch occurs in frequently, anatomical presence of a complete superficial palmar arch varies from 84% to 66% [Coleman & Anson]. This incidence was lower in the c urrent study and might be a reflection of sample size [52 hands]. The median artery was found in 10% of the hands, similar frequency to that reported by McCormack et al. [1953].

Historically, the dorsal arterial system of the hand received less attention than the palmar system. The studies concerning dorsal arterial anatomy present some controversies regarding the origin and presence of the dorsal metacarpal artery branches. Knowledge of the anatomy of dorsal metacarpal arteries is especially applied in the surgical planning for flaps taken from the dorsum of the hand. The purpose of this study is to analyze the arterial anatomy of the dorsum of the hand, compare our observations with those of previous studies from the literature, and therefore to define parameters for surgical planning for flaps supplied by the dorsal metacarpal arteries. METHOD: Twenty-six dissections were performed at the dorsum of the right hand of 26 cadavers by making a distal-based U-shaped incision. After catheterization of the radial artery at the wrist level, a plastic dye solution with low viscosity and quick solidification was injected to allow adequate exposure of even small vessels. The radial artery and its branches, the dorsal arterial arch, the dorsal metacarpal arteries, the distal and proximal communicating branches of the palmar system, and the distal cutaneous branches were carefully dissected and identified. RESULTS: The distal cutaneous branches originating from the dorsal metacarpal arteries were observed in all cases; these were located an average of 1.2 cm proximal from the metacarpophalangeal joint. The first dorsal metacarpal artery presented in 3 different patterns regarding its course: fascial, subfascial, and mixed. The branching pattern of the radial artery at the first intermetacarpal space was its division into 3 branches. We observed the presence of the dorsal arterial arch arising from the radial artery in 100% of the cases. The distance between the dorsal arterial arch and the branching point of the radial artery was an average of 2 cm. The first and second dorsal metacarpal arteries were visualized in all cases. The third and fourth dorsal metacarpal arteries were visualized in 96.2% and 92.3% of cases, respectively. There was proximal and distal communication between the dorsal arterial arch and the palmar system through the communicating branches contributing to the dorsal metacarpal artery formation. CONCLUSION: At the dorsum of the hand there is a rich arterial net that anastomoses with the palmar arterial system. This anatomical characteristic allows the utilization of the dorsal aspect of the hand as potential donor site for cutaneous flaps.Historicamente o sistema arterial dorsal da mão recebeu menos atenção em relação ao palmar. Os trabalhos que abordam a anatomia arterial dorsal apresentam pontos divergentes no que se refere a origem, a freqüência e a presença de ramos das artérias metacarpais dorsais. Este conhecimento se aplica, em especial, no planejamento cirúrgico de retalhos que tenham como área doadora o dorso da mão. O objetivo deste trabalho é o de estudar a anatomia do sistema arterial dorsal da mão, confrontando estes achados com os da literatura e desta maneira, definir parâmetros para o planejamento dos retalhos supridos pelas artérias metacarpais dorsais da mão. CASUÍSTICA E MÉTODO: Foram realizadas 26 dissecções na região dorsal da mão direita de 26 cadáveres, através de uma incisão em forma de U de base distal. Após a cateterização da artéria radial a nível do punho, foi injetado um corante plástico de baixa viscosidade e rápida solidificação que permitiu adequada visibilização até mesmo de pequenos vasos. A artéria radial e seus ramos, o arco dorsal, as artérias metacarpais dorsais, os ramos comunicantes distais e proximais do sistema palmar e os ramos cutâneos distais, foram cuidadosamente dissecados e identificados. RESULTADOS: Os ramos cutâneos distais provenientes das artérias metacarpais dorsais foram observados em todos os casos, em média, a 1,2 cm proximal a articulação metacarpo-falangeana. A primeira artéria metacarpal dorsal apresentou três padrões diferentes em relação ao seu trajeto no primeiro espaço intermetacarpal: fascial, subfascial e misto. O padrão de ramificação da artéria radial, no primeiro espaço intermetacarpal, foi o de sua divisão em três ramos. Observamos a presença do arco arterial dorsal em 100% dos casos, com sua origem na artéria radial. A distância entre a emergência do arco dorsal e o ponto de ramificação da artéria radial foi em média de 2 cm. As artérias primeira e segunda metacarpais dorsais estiveram presentes em todos os casos. As artérias terceira e quarta metacarpais dorsais estiveram presentes em 96,2% e 92,3% dos casos, respectivamente. Constatamos que houve uma comunicação proximal e distal do arco dorsal com o sistema palmar, através de ramos comunicantes que contribuíram para a formação das artérias metacarpais dorsais. CONCLUSÃO: Existe uma rica rede arterial no dorso da mão, que apresenta um grande número de anastomoses com o sistema arterial palmar, permitindo a utilização desta região como uma fonte potencial de retalhos cutâneos.

As infecções cirúrgicas são um dos principais problemas a nível hospitalar, contribuindo para o sofrimento dos doentes devido à dor, atraso na cicatrização e consequentemente aumento do tempo de hospitalização. Representam 13% das infecções nosocomiais, dos quais 56,9% são devidas a infecções do local cirúrgico. Esta problemática encontra-se muitas vezes associada a microorganismos com várias resistências antimicrobianas, como a Escherichia coli, Pseudomonas aeruginosa e Staphylococcus aureus (incluindo o S. aureus meticilino-resistente), consequência da utilização de antibióticos de largo espectro. Como tal, pretendeu-se contribuir para o desenvolvimento de novas estratégias de combate a infecções cirúrgicas, através da sobreexpressão de péptidos antimicrobianos, nomeadamente, a utilização de β-defensinas humanas (HBD). Esta sobreexpressão foi efectuada utilizando vectores lentivirais, contendo os respectivos genes, que foram introduzidos no modelo cirúrgico com ratos Wistar. De modo a verificar a capacidade antimicrobiana das HBD seleccionadas, procedeu-se previamente ao estabelecimento e caracterização de culturas das bactérias Pseudomonas aeruginosa ou Staphylococcus aureus. Posteriormente estas bactérias foram usadas para infectar o modelo cirúrgico, obtendo-se diferentes graus de infecção consoante a concentração de bactérias utilizadas. Verificou-se em resultados preliminares, uma diminuição da proliferação das bactérias presentes nos modelos cirúrgicos, sempre que se introduziam vectores lentivirais expressando os genes que codificam as HBD. Mais estudos estão a decorrer por forma a confirmar o papel antimicrobiano das HBD no modelo de infecção., Surgical infections are a major problem in hospital, contributing to the suffering of the patients due to pain, delayed healing and, hence increased length of hospitalization. These infections represent 13% of nosocomial infections, of which 56.9% are due to surgical site infections. This problem is often associated with antimicrobial resistance of various microorganisms, such as Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus), as a consequence of the use of broad spectrum antibiotics. In this thesis, it was intended to contribute to the development of new strategies to combat surgical infections, through the overexpression of antimicrobial peptides, in particular, the use of human β-defensins (HBD). HBD overexpression was performed using lentiviral vectors containing the respective genes which have been introduced in the surgical model with rats. In order to verify the efficacy of HBD, we first optimzed and characterized cultures of P. aeruginosa or S. aureus bacteria. Thereafter these bacteria were used to infect the surgical model, obtaining different degrees of infection depending on the concentration of bacteria used. Preliminary results, revealed a decrease in the proliferation of bacteria in surgical models, where lentiviral vectors expressing the HBD genes were introduced. Further studies are in progress in order to confirm the antimicrobial role of HBD in the infection rat model., Orientação : Paula Videira ; Orientação Interna : Susana Santos ; Co-orientação : José Ramalho ; Diogo Casal

On the one hand the heterogeneity of the circulatory system requires the use of different models in its different compartments, featuring different assumptions on the spatial degrees of freedom. On the other hand, the mutual interactions between its compartments imply that these models should preferably not be considered separately. These requirements have led to the concept of geometrical multiscale modeling, where the main idea is to couple 3D models with reduced 1D and/or 0D models. As such detailed information on the flow field in a specific region of interest can be obtained while accounting for the global circulation. However, the combination of models with different mathematical features gives rise to many difficulties such as the assignment of boundary conditions at the interface between two models and the development of robust coupling algorithms, as the subproblems are usually solved in a partitioned way. This review aims to give an overview of the most important aspects concerning 3D-1D-0D coupled models. In addition, some applications are presented in order to illustrate the potentialities of these coupled models.

Atalgın, Şükrü Hakan (Balikesir Author), Bu çalışmada, Mudurnu yöresinden temin edilen 2 adet balıkçıl kuşu kullanıldı. Renklendirilmiş latex enjekte edilen damarların diseksiyonu yapılarak bulgular kaydedildi. Birkaç istisna dışında diğer kanatlılarda da olduğu gibi balıkçıllarda aorta descendens’in ilk visceral dalı olan a. celiaca’nın esophagus, gaster, hepar, lien, pankreas ve bağırsakların bir kısmını besleyen damarların ortak kökü olduğu gözlenmiştir. A. celiacae’nın önce aa. lienalis adlı damarlarla lien’i beslediği daha sonra r. dexter ve r. sinister adlı iki dala ayrıldığı tespit edildi. Ramus dexter’in r. sinister’e nazaran daha uzun ve kalın olduğu, seyri esnasında a. jejunalis, a. pancreaticoduodenalis, a. hepatica dextra, a. vesicae biliaris’i verdikten sonra a. hepatica sinistra olarak karaciğer’in sol lobunda dağıldığı belirlendi. Ramus sinister’in ise a. gastrica sinistra ve duodenum’un beslenmesi için birkaç dal verdiği görüldü. A. mesenterica cranialis’in a. celiaca’nın orijininden yaklaşık 1.5 cm sonra aorta descendens’ten çıktığı, barsakların son kısmı hariç tamamını beslediği izlendi. Böbrekleri aorta abdominalis’ten direkt çıkan a. renalis cranialis ve a ischiadica’dan çıkan damarların beslediği saptandı. Aorta descendens’in rectum için a. mesenterica caudalis’i verdikten sonra a. iliaca externa’ları oluşturarak sonlandığı tespit edildi. Çalışmada, balıkçıl kuşunun karın bölgesi organlarının arteriel beslenmesi incelenmiş ve diğer kanatlılarla olan farklılık ve benzerlikleri ortaya çıkarılarak elde edilen bulgular sunulmuştur., Two herons provided from Mudurnu region were used in the study. The materials were injected with red-coloured latex through the aorta. A. celiacae originated from aorta abdominalis. A. celiacae was determined as sending the aa. lienalis and continued as the r. dexter a. celiacae and r. sinister a. celiacae. R. dexter a. celiacae was longer and thicker than ramus sinister a. celiacea and it was splitted into the left lobe of hepar, as a. hepatica sinistra, then gave as a. hepatica dextra, a. hepatica sinistra, a. pancreaticoduodenalis, a. jejenualis and a. vesicae biliaris. It was seen that ramus sinister a. celiacae gave several branches to nourish duodenum and a. gastrica sinistra. A. mesenterica cranialis, after appoximately 1.5 cm of a. celiaca’s origin, was determined as coming out from the aorta descendens and except the last part of entrails that was seen to nourish the whole one. R. sinister a. celiaca gave r. dorsalis and r. ventralis. The kidneys were supplied by the a. renalis cranialis and braches of a. ischiadica. After giving a. mesenterica cranialis for rectum, aorta descendens terminated to form a. iliaca externa. The arteriel vascularisations of abdominal region of heron’s organs were examined and differences and similarities obtained were presented herein.

Çalışmada Mudurnu yöresinden temin edilen 21 adet bıldırcın (Coturnix coturnix japonica) kullanıldı . Arteriel sisteme renklendirilmiş latex solusyonu verilerek karın boşluğu organlarının ve genital sistemin arteriel dallanması temin edildi. A. celiaca'dan ayrılan damarların proventriculus, ventriculus, duodenum, ileum, secum ve pancreası vaskularize ettiği, a. mesenterica cranialis'in duodenum, jejunum, ileum ve secum'a dallar gönderdiği, a. mesenterica caudalis'in ileum ve secum'u beslediği böbreklerin a. renalis cranialis, media ve caudalis tarafından beslendiği görüldü. Genital sistemde ise ovarium'un a. ovarica, oviduct'un ise a. oviductalis cranialis, a. oviductalis cranialis accessoria, a. oviductalis media, a. oviductalis caudalis, va a. vaginalis tarafından beslendiği saptandı. In this study, colored latex was enjected into to the arteriel system to investigate the arteriel vascularisation of the viscera and female sex organs of the 21 quails obtained from Mudurnu region. The coeliac artery supplied the proventrlculus, gizzard, duodenum, ileum, caeca, and pancreas. The cranial mesenteric artery distributed braches to the duodenurn, jejenum, ileum, and caeca. The caudal mesenteric artery supplied the ileurn and rectum. The kidneys were supplied by the cranial, middle, and caudal renal arteries. The left gonad was supplied by the ovarian artery or arteries. The oviduct was supplied by the cranlal oviductal artery. accessory cranial oviductal artery, middle oviduetal artery, eaudal oviductal artery, and cranial oviductal artery. The vaginal artery supplied the vagina.

To facilitate the quantitative analysis of post-occlusive reactive hyperaemia (PORH), measured with laser-Doppler perfusion monitoring (LDPM) on extremities, we present a flow model for the dynamics of the perfusion of the tissue during PORH, based on three parameters: two time constants (/spl tau//sub 1/ and /spl tau//sub 2/) and the ratio of the maximum flux and the resting flux. With these three constants quantitative comparisons between experiments will be possible and, therefore, we propose to adopt this approach as future standard. For this reason, we also developed a computer program to perform the fit of the model to measured data.

Historically, the dorsal arterial system of the hand received less attention than the palmar system. The studies concerning dorsal arterial anatomy present some controversies regarding the origin and presence of the dorsal metacarpal artery branches. Knowledge of the anatomy of dorsal metacarpal arteries is especially applied in the surgical planning for flaps taken from the dorsum of the hand. The purpose of this study is to analyze the arterial anatomy of the dorsum of the hand, compare our observations with those of previous studies from the literature, and therefore to define parameters for surgical planning for flaps supplied by the dorsal metacarpal arteries. METHOD: Twenty-six dissections were performed at the dorsum of the right hand of 26 cadavers by making a distal-based U-shaped incision. After catheterization of the radial artery at the wrist level, a plastic dye solution with low viscosity and quick solidification was injected to allow adequate exposure of even small vessels. The radial artery and its branches, the dorsal arterial arch, the dorsal metacarpal arteries, the distal and proximal communicating branches of the palmar system, and the distal cutaneous branches were carefully dissected and identified. RESULTS: The distal cutaneous branches originating from the dorsal metacarpal arteries were observed in all cases; these were located an average of 1.2 cm proximal from the metacarpophalangeal joint. The first dorsal metacarpal artery presented in 3 different patterns regarding its course: fascial, subfascial, and mixed. The branching pattern of the radial artery at the first intermetacarpal space was its division into 3 branches. We observed the presence of the dorsal arterial arch arising from the radial artery in 100% of the cases. The distance between the dorsal arterial arch and the branching point of the radial artery was an average of 2 cm. The first and second dorsal metacarpal arteries were visualized in all cases. The third and fourth dorsal metacarpal arteries were visualized in 96.2% and 92.3% of cases, respectively. There was proximal and distal communication between the dorsal arterial arch and the palmar system through the communicating branches contributing to the dorsal metacarpal artery formation. CONCLUSION: At the dorsum of the hand there is a rich arterial net that anastomoses with the palmar arterial system. This anatomical characteristic allows the utilization of the dorsal aspect of the hand as potential donor site for cutaneous flaps. Historicamente o sistema arterial dorsal da mão recebeu menos atenção em relação ao palmar. Os trabalhos que abordam a anatomia arterial dorsal apresentam pontos divergentes no que se refere a origem, a freqüência e a presença de ramos das artérias metacarpais dorsais. Este conhecimento se aplica, em especial, no planejamento cirúrgico de retalhos que tenham como área doadora o dorso da mão. O objetivo deste trabalho é o de estudar a anatomia do sistema arterial dorsal da mão, confrontando estes achados com os da literatura e desta maneira, definir parâmetros para o planejamento dos retalhos supridos pelas artérias metacarpais dorsais da mão. CASUÍSTICA E MÉTODO: Foram realizadas 26 dissecções na região dorsal da mão direita de 26 cadáveres, através de uma incisão em forma de U de base distal. Após a cateterização da artéria radial a nível do punho, foi injetado um corante plástico de baixa viscosidade e rápida solidificação que permitiu adequada visibilização até mesmo de pequenos vasos. A artéria radial e seus ramos, o arco dorsal, as artérias metacarpais dorsais, os ramos comunicantes distais e proximais do sistema palmar e os ramos cutâneos distais, foram cuidadosamente dissecados e identificados. RESULTADOS: Os ramos cutâneos distais provenientes das artérias metacarpais dorsais foram observados em todos os casos, em média, a 1,2 cm proximal a articulação metacarpo-falangeana. A primeira artéria metacarpal dorsal apresentou três padrões diferentes em relação ao seu trajeto no primeiro espaço intermetacarpal: fascial, subfascial e misto. O padrão de ramificação da artéria radial, no primeiro espaço intermetacarpal, foi o de sua divisão em três ramos. Observamos a presença do arco arterial dorsal em 100% dos casos, com sua origem na artéria radial. A distância entre a emergência do arco dorsal e o ponto de ramificação da artéria radial foi em média de 2 cm. As artérias primeira e segunda metacarpais dorsais estiveram presentes em todos os casos. As artérias terceira e quarta metacarpais dorsais estiveram presentes em 96,2% e 92,3% dos casos, respectivamente. Constatamos que houve uma comunicação proximal e distal do arco dorsal com o sistema palmar, através de ramos comunicantes que contribuíram para a formação das artérias metacarpais dorsais. CONCLUSÃO: Existe uma rica rede arterial no dorso da mão, que apresenta um grande número de anastomoses com o sistema arterial palmar, permitindo a utilização desta região como uma fonte potencial de retalhos cutâneos.

The number of patients that are waiting for heart transplants far exceed the number of available donor hearts. Left Ventricular Assist Devices are mechanical alternatives that can help and are helping several patients. They work by taking blood from the left ventricle and ejecting that blood into the aorta. In the University of Louisville they are developing a similar device that will take the blood from the aorta instead of the ventricle. This new device is called an Artificial Vasculature Device. In this thesis the arterial system and AVD are modeled and a simple control algorithm for the AVD proposed. The arteries are modeled as a tube with linear resistance and inertia followed by a chamber with linear compliance and last a tube with linear resistance. The model is identical to the 4-element Windkessel model. The values for the resistances, inertia and compliance are identified using pressure and flow measurements from the ventricle and aortic root from a healthy patient. In addition to the Windkessel model the aortic valve is also modeled. The valve is modeled as a drum that closes the aorta and the parameters identified like before. The measurements are also used to model the left ventricle by assuming it has a constant compliance profile. The AVD is modeled using common modeling structures for servo motors and simple structures for tubes and pistons. The values for the AVD could not be measured and identified so they are fetched from preliminary motor and part specifications. The control algorithm for the AVD uses a wanted load to create a reference aortic flow. This wanted aortic flow is then achieved by using a PI controller. With these models and controller the interaction between the arterial system and AVD is investigated. With this preliminary understanding of the interaction further research can be made in the future to improve the understanding and improve the AVD itself.

Although the primitive vasculature is identical in XX and XY genital ridges until 11.5 days postcoitum (dpc), by 12.5 dpc the XY gonad develops a distinct vasculature. This male-specific vasculature, which includes the development of a large coelomic vessel, develops coincident with expression of Sry and formation of testis cords. We show that similar levels of proliferation and vasculogenesis expand the primary vasculature in XX and XY gonads. However, soon after Sry expression begins, the XY gonad recruits a large number of endothelial cells from the adjacent mesonephros, a mechanism totally absent in XX gonads. These migrating cells do not contribute to venous or lymphatic development. Instead, these cells contribute to the arterial system, as indicated by expression of ephrinB2 and by elements of the Notch signaling pathway. This newly formed arterial system establishes a new pattern of blood flow in the XY gonad, which we speculate may have an important role in export of testosterone to masculinize the XY embryo.

SUMMARY: Liver plays an important role in many events such as bile production, blood filtration and metabolic functions. The liver is supplied by the hepatic arterial system. The hepatic arterial system anatomy has a variable structure and the rate of variation is high. In our study, we aimed to determine the diameters and variation of the arteries supplying the liver with multidetector computed tomography images. In this study, hepatic arterial system variations of 500 cases whose abdominal region was imaged with multi- detector computed tomography were evaluated and the diameters of the related arteries were measured. The mean diameters of classical and variational anatomy were determined in this study. According to mean measurements of classical and variational anatomy were abdominal aorta 21.95 mm, celiac artery 7.2 mm, common hepatic artery 4.3 mm, proper hepatic artery 2.93 mm, right hepatic artery 2.92 mm, left hepatic artery 2.51 mm and abdominal aorta 21.85 mm, celiac artery 6.99 mm, common hepatic artery 5.07 mm, proper hepatic artery 3.83 mm, right hepatic artery 2.87 mm ve left hepatic artery 2.09 mm respectively. When evaluated in terms of variations, 85.6 % of the cases had branching according to Type I, 14.4 % of the cases had different branching patterns. Type III (87.5 %) was the most observed variation among them. As a result of the study, it was determined that the arterial diameters vary according to the state of variation and that the arterial diameter of men are greater than that of women.