Academic literature on the topic 'Distal-SO'
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Journal articles on the topic "Distal-SO"
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Maebashi, Manabu, Kentaro Miyake, Yasuhiro Shimizu, Gakuryu Nakayama, Yasuhiro Yabushita, Yuki Homma, Takahumi Kumamoto, Ryusei Matsuyama, Mitsuko Furuya, and Itaru Endo. "A Case of So-Called Sarcomatoid Carcinoma in the Distal Bile Duct." Japanese Journal of Gastroenterological Surgery 54, no. 4 (April 1, 2021): 262–69. http://dx.doi.org/10.5833/jjgs.2020.0061.
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Suzuki, T., W. J. Dodds, S. K. Sarna, W. J. Hogan, R. A. Komorowski, and Z. Itoh. "Control mechanisms of sphincter of Oddi contraction rate in the opossum." American Journal of Physiology-Gastrointestinal and Liver Physiology 255, no. 5 (November 1, 1988): G619—G626. http://dx.doi.org/10.1152/ajpgi.1988.255.5.g619.
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Our aim in this study is to determine whether extrinsic autonomic nerves regulated spike-burst rate in the opossum sphincter of Oddi (SO) during fasting or after feeding. We implanted electrodes on the distal SO, proximal SO, gastric antrum, duodenum, and jejunum of 20 animals. A cut transection and reanastomosis was done at different levels of the SO to interrupt putative extrinsic or intrinsic nerves, or the SO was painted with phenol to impair extrinsic nerves. Like controls, animals with a cut and reanastomosis at the proximal SO or at the SO-duodenal junction showed a normal fasting pattern of cyclic changes in SO spike-burst rate. In contrast, animals treated by a distal SO cut or phenol treatment at the distal SO lost the normal cyclic pattern of SO spike bursts and had a constant rate of approximately 4/min. A cut through the middle SO uncoupled the spike bursts in the proximal and distal SO. After feeding, all animals developed an SO spike-burst rate of 5-6/min that lasted for several hours. We conclude that the normal fasting pattern of SO spike bursts is regulated by extrinsic nerves that ascend cephalad along the sphincter segment, whereas the sustained increase in SO spike-burst rate after feeding is at least in part hormonal.
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Mattei, Jean-Camille, Véronique Brouste, Philippe Terrier, Sylvie Bonvalot, Axel Lecesne, Eberhard Stoeckle, Antoine Italiano, et al. "Distal extremities soft tissue sarcomas: Are they so different from other limb localizations?" Journal of Surgical Oncology 119, no. 4 (January 4, 2019): 479–88. http://dx.doi.org/10.1002/jso.25359.
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Lee, Na Young, Stephanie M. Noble, and Alex R. Zablah. "So distant, yet useful: The impact of distal stories on customers’ service expectations." Journal of Business Research 113 (May 2020): 230–42. http://dx.doi.org/10.1016/j.jbusres.2020.01.044.
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Parkar, AAH, S. Marya, and S. Auplish. "Distal radius triplane fracture." Annals of The Royal College of Surgeons of England 96, no. 8 (November 2014): e6-e7. http://dx.doi.org/10.1308/003588414x13946184902569.
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A triplane fracture is so named because of the three planes traversed by the fracture line. These are physeal fractures that result from injury during the final phase of maturation and cessation of growth. This fracture pattern typically involves the distal tibia. We present a rare case of a triplane fracture involving the distal radius.
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Jahangir, Jabed, Md Iqbal Hossain, Md Myen Uddin Mojumder, Mohammad Hossain, Md Anwar Hossain, and Md Imroz Uddin. "Management of Distal Femoral Fracture with Distal Femoral Nail." Chattagram Maa-O-Shishu Hospital Medical College Journal 16, no. 2 (July 3, 2018): 44–47. http://dx.doi.org/10.3329/cmoshmcj.v16i2.37293.
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Background: For a long time distal femur fracture were considered difficult to heal and often led to a degree of disability. The incidence of malunion, nonunion and infection are relatively high in many reported series. The management goal of distal femur fractures are correction of axial alignment, length, and rotation, restoration of motion and rapid union so as to return the patient to normal function. We present here result of retrograde nailing of extra-articular (AO 33A1 to A3) fractures of the distal femur using Distal Femoral Nail (DFN).Methods: In Between 2008 to 2010 total 17 patients (One lost to follow up so 16 available for final assessment) underwent open reduction and internal fixation for distal femoral fracture in Chittagong Medical College Hospital and Private Hospital in Chittagong city. There were 13 male and 3 female patients, age range from 18 years to 70 years, mean age 42.75 years. Average length of follow-up was 17.5months (12 months to 24 months).Results: Total 16 patients was available for follow up. Regular fracture healing was observed in 14 cases. Delayed union in 2 case. One patient had infection, and two patients had leg shorting of 0.5 and 1 cm. Axial misalignment (Varus/valgus angulations) was found in 4 cases (5º-10º) there were no implant failures. On the bases of a Leung score to measure functional outcome, 4 cases had excellent, 8 cases had good and 4 cases had fair result. Poor results were not seen in any patient. In this series 13 cases were satisfactory and 3 cases were unsatisfactory.Conclusion: Distal Femoral Nail is handsome tool to treat distal femoral fracture.Chatt Maa Shi Hosp Med Coll J; Vol.16 (2); July 2017; Page 44-47
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YAMAGUCHI, Ryuichi, Nobuyuki ITO, Eiji MAEMURA, Yoshiaki SHIOKAWA, and Isamu SAITO. "Bilateral Distal Anterior Cerebral Artery Aneurysms Mimicking So-called "Kissing Aneurysms": A Case Report." Surgery for Cerebral Stroke 31, no. 3 (2003): 197–202. http://dx.doi.org/10.2335/scs.31.197.
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Worcester, Elaine M., Fredric L. Coe, Andrew P. Evan, Kristin J. Bergsland, Joan H. Parks, Lynn R. Willis, Daniel L. Clark, and Daniel L. Gillen. "Evidence for increased postprandial distal nephron calcium delivery in hypercalciuric stone-forming patients." American Journal of Physiology-Renal Physiology 295, no. 5 (November 2008): F1286—F1294. http://dx.doi.org/10.1152/ajprenal.90404.2008.
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A main mechanism of idiopathic hypercalciuria (IH) in calcium stone-forming patients (IHSF) is postprandial reduction of renal tubule calcium reabsorption that cannot be explained by selective reduction of serum parathyroid hormone levels; the nephron site(s) responsible are not as yet defined. Using fourteen 1-h measurements of the clearances of sodium, calcium, and endogenous lithium during a three-meal day in the University of Chicago General Clinical Research Center, we found reduced postprandial proximal tubule reabsorption of sodium and calcium in IHSF vs. normal subjects. The increased distal sodium delivery is matched by increased distal reabsorption so that urine sodium excretions do not differ, but distal calcium reabsorption does not increase enough to match increased calcium delivery, so hypercalciuria results. In fact, urine calcium excretion and overall renal fractional calcium reabsorption both are high in IHSF vs. normal when adjusted for distal calcium delivery, strongly suggesting a distal as well as proximal reduction of calcium reabsorption. The combination of reduced proximal tubule and distal nephron calcium reabsorption in IHSF is a new finding and indicates that IH involves a complex, presumably genetic, variation of nephron function. The increased calcium delivery into the later nephron may play a role in stone formation via deposition of papillary interstitial apatite plaque.
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Helm, J. F., W. J. Dodds, J. Christensen, and S. K. Sarna. "Intramural neural control of opossum sphincter of Oddi." American Journal of Physiology-Gastrointestinal and Liver Physiology 257, no. 6 (December 1, 1989): G925—G929. http://dx.doi.org/10.1152/ajpgi.1989.257.6.g925.
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We evaluated the intramural neural control of the opossum sphincter of Oddi (SO) in an in vitro preparation. Force transducers were used to record contractions at four sites along the sphincter segment. To stimulate intramural nerves, 10- to 120-s trains of pulses (4-10 V amplitude, 0.5 ms duration, and 5 Hz frequency) were delivered to one of three electrode pairs implanted along the SO. Electrical stimulation in the proximal, mid, or distal SO elicited phasic contractions that invariably originated in the proximal SO and propagated antegrade along the entire length of the sphincter segment. Stimulus-evoked contractions resembled spontaneous antegrade peristaltic contractions, but occurred at a higher rate (12-20/min). Atropine completely blocked this excitatory response to nerve stimulation. After atropine, nerve stimulation in the proximal, mid, or distal SO abolished spontaneous contractions at and distal to the site of stimulation for the duration of the stimulus. The inhibitory response to nerve stimulation was completely blocked by tetrodotoxin but was unaffected by phenoxybenzamine, tolazoline, or propranolol. We conclude that 1) the opossum SO is innervated by intramural cholinergic excitatory nerves and nonadrenergic noncholinergic inhibitory nerves; 2) cholinergic excitatory nerves are organized in ascending neural pathways, whereas nonadrenergic noncholinergic inhibitory nerves descend along the length of the SO; and 3) these neural pathways may modulate SO peristalsis in vivo and participate in ascending excitatory and descending inhibitory reflexes.
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Helm, J. F., W. J. Dodds, J. Christensen, and S. K. Sarna. "Control mechanism of spontaneous in vitro contractions of the opossum sphincter of Oddi." American Journal of Physiology-Gastrointestinal and Liver Physiology 249, no. 5 (November 1, 1985): G572—G579. http://dx.doi.org/10.1152/ajpgi.1985.249.5.g572.
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We evaluated the control mechanism of peristaltic contractions in the opossum sphincter of Oddi (SO) by means of an in vitro preparation. At each of four sites spaced uniformly along the sphincter segment, a force transducer recorded contractions while a monopolar electrode recorded myoelectric activity. Spontaneous myoelectric and contractile activity occurred in 15 of the 20 intact SO specimens studied. Electrical recordings showed characteristic control waves and response activity. Each control wave was invariably accompanied by a phasic contraction, irrespective of whether or not response activity was superimposed on the control wave. The predominant motor activity of the SO was antegrade peristalsis. Retrograde peristalsis occurred when antegrade peristalsis failed to traverse the entire sphincter. Spontaneous SO phasic contractions were not antagonized by tetrodotoxin. Muscle rings sectioned from the SO exhibited spontaneous phasic contractions with a proximal-to-distal gradient of intrinsic contraction frequencies. We conclude that a) the frequency of SO phasic contractions is determined by control wave frequency, b) spontaneous SO peristalsis is myogenic in origin and may be modeled by a linear array of bidirectionally coupled relaxation oscillators, c) the predominance of antegrade peristalsis may be explained by a high-frequency oscillator in the proximal SO that drives the slower, more distal oscillators, d) retrograde peristalsis is initiated by an ectopic oscillator in the distal SO when antegrade contractions fail to propagate the entire length of the SO, and e) ectopic SO contractions can propagate retrograde when the more proximal oscillators are not in their absolutely refractory state.
Dissertations / Theses on the topic "Distal-SO"
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Woods, Charmaine Michelle, and charmaine woods@flinders edu au. "EXOGENOUS PURINES INDUCE DIFFERENTIAL RESPONSES IN THE PROXIMAL AND DISTAL REGIONS OF THE SPHINCTER OF ODDI: PARTIAL CHARACTERISATION OF THE PURINERGIC RECEPTOR SUB-TYPES INVOLVED." Flinders University. School of Medicine, 2006. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20061120.095902.
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The sphincter of Oddi (SO) is a neuromuscular structure located at the junction of the bile and pancreatic ducts with the duodenum. The primary functions of the SO are to regulate the delivery of bile and pancreatic juice into the duodenum, and to prevent reflux of duodenal contents into the biliary and pancreatic systems. Neural, hormonal or functional disturbances of biliary motility can lead to painful and sometimes life threatening clinical conditions, such as SO dysfunction and acute pancreatitis. Clearly understanding the regulation of biliary and duodenal motility patterns is necessary and may provide useful pharmacological sites for drug development to aid in the treatment of these diseases.
Spontaneous activity of the SO is regulated by complex interactions between the enteric nervous system, hormones, possibly interstitial cells of Cajal and other bioactive agents, together with modulation via neural reflexes between the duodenum, common bile duct/gallbladder, and stomach. Purines are one group of neurotransmitters/regulatory agents that have been shown to effect gastrointestinal motility, however their functions in the regulation of SO motility have not been elucidated.
The studies described in this thesis used in vitro organ bath techniques and in vivo preparations to determine the effects of exogenous purines on possum SO and duodenal motility. The possum SO has been extensively characterized and is an excellent model for motility studies. In vitro, exogenous adenosine was found to decrease spontaneous activity in both the SO and duodenum. In contrast exogenous ATP induced both excitatory and inhibitory responses in the SO and duodenum. Interestingly, the adenosine and ATP-induced effects were predominantly exhibited by the proximal portion of the SO (proximal-SO), with no or little effect observed in the distal portion of the SO (distal-SO). These data support the hypothesis that the SO is comprised of different functional components that can act differently in response to certain stimuli, and highlights the importance of studying each of the SO components.
Agonists and antagonists, together with immunohistochemical studies, were used in an attempt to identify the P1 and P2 receptor sub-types responsible for mediating the adenosine- and ATP-induced responses. In the duodenum the adenosine-induced decrease in spontaneous activity was likely to be mediated by A2A and A3 receptors, but the receptors mediating the proximal-SO response could not be identified. In the duodenum ATP induced a complex non-neural response consisting of a P2X1, and P2Y2 and/or P2Y4 mediated immediate inhibition. This was followed by a return to baseline activity or small excitation. The response concluded with a late inhibitory response, likely to be mediated by P2Y1 receptors, but the effects of other P2Y receptors could not be excluded. In contrast, ATP application to the proximal-SO evoked a partially neurally mediated early excitation, likely via P2X receptors, followed by an inhibition of activity, likely via activation of non-neural P2Y2 and/or P2Y4 receptors.
In vivo studies with exogenous application of adenosine and ATP to the SO activated neural pathways to produce increased motor activity. Characterisation of these neural pathways found ATP and/or adenosine to activate excitatory cholinergic motor neurons. ATP also activated an inhibitory nicotinic/nitrergic pathway.
This is the first comprehensive investigation of the possible involvement of purines in the regulation of SO motility. These studies demonstrate that exogenous purines influence SO and duodenal motility, inducing complex neural and non-neural responses, acting via multiple P1 and P2 receptors. It now remains to be determined if endogenously released purines induce similar responses, together with elucidation and location of the receptor sub-types involved.
Books on the topic "Distal-SO"
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Bass, A. Fractures and dislocations about the paediatric forearm. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199550647.003.014006.
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♦ Growth plate fractures are common and of these the commonest is a Salter–Harris type II through the distal radial physis. There is considerable capacity for remodelling so reduction may not be needed. Remodelling capacity is inversely proportional to age♦ Elastic intramedullary nails are valuable in the forearm♦ Complications of fractures include malunion, refracture, and cross union.
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Shaibani, Aziz. Deformities. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199898152.003.0024.
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Deformities are important markers for congenital and hereditary neuromuscular disorders. Kyphosis, scoliosis, Pes Cavus, for example, are common in CMT and hereditary ataxias. Deformities may also result from long-term weakness and asymmetry. Chronic neuropathies with distal weakness may lead to gradual changes in the height of feet arches. A high foot arche that is corrected with wight bearing or manually, is usually not congenital. Other types of deformities are related to connective tissue pathology, which can be associated with neuromuscular disorders, for example multiple lipomatosis, scleroderma, contractures, nephrogenic systemic sclerosis, and so on. This chapter shows examples of these deformities. Musculoskeletal deformities may lead to entrapment neuropathies.
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Wagner, Carsten A., and Olivier Devuyst. Renal acid–base homeostasis. Edited by Robert Unwin. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199592548.003.0024.
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The kidney is central to acid–base homeostasis. Major processes are reabsorption of filtered bicarbonate, de novo synthesis of bicarbonate from ammoniagenesis, and net excretion of protons. The latter requires buffers such as ammonium, phosphate, citrate and other bases binding protons (so-called titratable acids). The proximal tubule is the major site of bicarbonate reabsorption and only site of ammoniagenesis. The thick ascending limb and the distal convoluted tubule handle ammonia/ammonium and complete bicarbonate reabsorption. The collecting duct system excretes protons and ammonium, but may switch to net bicarbonate secretion. The kidney displays a great plasticity to adapt acid or bicarbonate excretion. Angiotensin II, aldosterone and endothelin are involved in regulating these processes, and they induce morphological changes along the nephron. Inborn and acquired disorders of renal acid–base handling are caused by mutations in acid–base transport proteins or by dysregulation of adaptive mechanisms.
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de Bie, Robertus M. A., and Susanne E. M. Ten Holter. “She Is So Fidgety”. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780190607555.003.0023.
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Chorea manifests as involuntary, often contnuous, unpredictable, and involuntary dance-like movements. Patients with chorea are often unaware that they have involuntary movements. Others may try to incorporate the movement into a semipurposeful action (parakinesia). Chorea is usually worse with mental activity or emotion. Physical activity may also exacerbate chorea. The presence of “motor impersistence” is typical of chorea. Sometimes patients can also make unintentional sounds referred to as hyperkinetic dysarthria. Chorea disappears during sleep. Ballism is considered a type of chorea with a more proximal distribution and larger movements. Athetosis is a term formally used for chorea with slow writing movements in the distal limbs, but it is not considered a specific entity of chorea anymore. The most important genetic cause of chorea in adulthood is Huntington’s disease, and genetic testing should be considered as a first step in all patients with adult-onset chorea if no secondary cause is found.
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Shaibani, Aziz. Pseudoneurologic Syndromes. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190661304.003.0022.
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The term functional has almost replaced psychogenic in the neuromuscular literature for two reasons. It implies a disturbance of function, not structural damage; therefore, it defies laboratory testing such as MRIS, electromyography (EMG), and nerve conduction study (NCS). It is convenient to draw a parallel to the patients between migraine and brain tumors, as both cause headache, but brain MRI is negative in the former without minimizing the suffering of the patient. It is a “software” and not a “hardware” problem. It avoids irritating the patient by misunderstanding the word psychogenic which to many means “madness.”The cause of this functional impairment may fall into one of the following categories:• Conversion reaction: conversion of psychological stress to physical symptoms. This may include paralysis, hemisensory or distal sensory loss, or conversion spasms. It affects younger age groups.• Somatization: chronic multiple physical and cognitive symptoms due to chronic stress. It affects older age groups.• Factions disorder: induced real physical symptoms due to the need to be cared for, such as injecting oneself with insulin to produce hypoglycemia.• Hypochondriasis: overconcern about body functions such as suspicion of ALS due to the presence of rare fasciclutations that are normal during stress and after ingestion of a large amount of coffee. Medical students in particular are targets for this disorder.The following points are to be made on this topic. FNMD should be diagnosed by neuromuscular specialists who are trained to recognize actual syndrome whether typical or atypical. Presentations that fall out of the recognition pattern of a neuromuscular specialist, after the investigations are negative, they should be considered as FNMDs. Sometimes serial examinations are useful to confirm this suspicion. Psychatrists or psychologists are to be consulted to formulate a plan to discover the underlying stress and to treat any associated psychiatric disorder or psychological aberration. Most patients think that they are stressed due to the illness and they fail to connect the neuromuscular manifestations and the underlying stress. They offer shop around due to lack of satisfaction, especially those with somatization disorders. Some patients learn how to imitate certain conditions well, and they can deceive health care professionals. EMG and NCS are invaluable in revealing FNMD. A normal needle EMG of a weak muscles mostly indicates a central etiology (organic or functional). Normal sensory responses of a severely numb limb mean that a lesion is preganglionic (like roots avulsion, CISP, etc.) or the cause is central (a doral column lesion or functional). Management of FNMD is difficult, and many patients end up being chronic cases that wander into clinics and hospitals seeking solutions and exhausting the health care system with unnecessary expenses.It is time for these disorders to be studied in detail and be classified and have criteria set for their diagnosis so that they will not remain diagnosed only by exclusion. This chapter will describe some examples of these disorders. A video clip can tell the story better than many pages of writing. Improvement of digital cameras and electronic media has improved the diagnosis of these conditions, and it is advisable that patients record some of their symptoms when they happen. It is not uncommon for some Neuromuscular disorders (NMDs), such as myasthenia gravis (MG), small fiber neuropathy, and CISP, to be diagnosed as functional due to the lack of solid physical findings during the time of the examination. Therefore, a neuromuscular evaluation is important before these disorders are labeled as such. Some patients have genuine NMDs, but the majority of their symptoms are related to what Joseph Marsden called “sickness behavior.” A patient with carpal tunnel syndrome (CTS) may unconsciously develop numbness of the entire side of the body because he thinks that he may have a stroke.
Book chapters on the topic "Distal-SO"
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Brunet, Marie-Christine, Stephanie H. Chen, Pascal M. Jabbour, and Eric C. Peterson. "Distal Transradial “Snuffbox” Approach." In Radial Access for Neurointervention, 23–30. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780197524176.003.0003.
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The distal radial or “snuffbox” approach is a modification of the traditional radial approach that uses a more distal location of the radial artery for puncture. The radial artery at this location is beyond the palmer arch thus puncturing has a theoretically lower risk of hand or thumb ischemia. In addition, the hand is positioned in the neutral position so it is more comfortable for the patient. Finally, the compression times are shorter so the patient can be discharged earlier after diagnostic procedures. This was originally an interventional cardiology innovation because of the frequent use of left radial access in interventional cardiology, but the approach has benefits for right radial access in neurointervention as well. The patient positioning and technical nuances of the snuffbox approach are reviewed.
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Neander, Karen. "Distal and Distant Red Squares." In A Mark of the Mental. The MIT Press, 2017. http://dx.doi.org/10.7551/mitpress/9780262036146.003.0009.
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The final chapter is about the notoriously difficult problem of distal content (the sixth of the content determinacy challenges listed in chapter 7). In relation to causal theories of reference, the problem is to explain why a representation counts as representing its content, rather than some other item that carries information about it to the sensory-perceptual system that produces the representation. After discussing how the problem concerns nonconceptual representations, as opposed to conceptualized thought, the author offers a solution suitable for nonconceptual representations. She explains why several well-known proposals do not seem to be even designed to assign appropriate distal contents to nonconceptual representations (whatever their success might or might not be for concepts). Neander alsoalso discusses several closely related issues, such as how a hallucinated red square might be experienced as “in the world,” versus “just in the head,” and how distal contents and perceptual constancies are related. Before concluding, the author discusses the issue of how informational teleosemantics handles the content of complex contents produced by the so-called “binding” of perceived features to perceived objects.
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Miller, Aaron E., Tracy M. DeAngelis, Michelle Fabian, and Ilana Katz Sand. "A Perplexing Pattern of Weakness." In Neuroimmunology, 205–8. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190693190.003.0039.
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Inclusion body myositis (IBM), generally considered one of the immune-mediated inflammatory myopathies, should be readily recognizable by its characteristic clinical features. The disorder typically affects middle-aged to older individuals and has a mean age of onset in the early 60s. Onset before the age of 40 is rare. The disease is characteristically asymmetrical and most often has the relatively unique pattern of involvement of the finger flexors (typically with relative sparing of the metacarpophalangeal flexors compared to the more distal finger flexors) and the quadriceps muscles. In the latter, disproportionate wasting of the vastus medialis and lateralis often occur, with relative sparing of the rectus femoris, so that knee extension is often only mildly weak compared to the observed atrophy. Another striking historical feature is the relatively insidious onset of symptoms in comparison to other inflammatory myopathies.
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Friedman, Jeffrey D., and Eric S. Ruff. "Soleus Flap for Lower Leg Reconstruction." In Operative Plastic Surgery, edited by Gregory R. D. Evans, 873–80. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780190499075.003.0086.
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Open wounds in the middle third of the lower leg often require soft tissue reconstruction to allow for primary wound healing. The soleus muscle flap is uniquely suited for this purpose and is used primarily as a muscle flap without the accompanying overlying skin. This muscle has a blood supply that is segmental in nature, arising from multiple perforators from the posterior tibial vessels. Given that that this blood supply is primarily located in the proximal third of the leg, the soleus muscle flap is generally based proximally to allow for coverage of middle-third defects. While the muscle has a clear intermuscular septum which separates the medial head from the lateral segment, the use of a so-called hemi-soleus flap is less reliable and thus used on an infrequent basis. The soleus muscle flap can also be based distally in the leg for small distal-third defects; however, this flap can often be unreliable due to a paucity of sufficient perforators located in this area.
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Emmett, Stevan R., Nicola Hill, and Federico Dajas-Bailador. "Renal medicine." In Clinical Pharmacology for Prescribing. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780199694938.003.0013.
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The kidneys are of fundamental importance in the regulation of fluid and electrolytes, maintaining permissive extracellular fluid composition (salts and water), pH, and volume, while also mediating the removal of waste products. Based on the anatomy of the nephron, three main processes occur in order to deliver this balance: glomerular filtration, tubular secretion, and tubular resorption. Drugs can act at different sites within this system, so that functional equilibrium can be restored in various disease states (e.g. hypertension, heart failure, liver failure, nephrotic syndrome). CKD is a long- term condition that lasts more than 3 months and affects the function of both kidneys. It results from any pathology that reduces renal functional capacity and produces a decrease in GFR to less than 60 mL/ min/ 1.73 m<sup>2</sup>. Prevalence within the UK is high, particularly in the elderly and affects 6– 8% of the population. The most common cause of CKD is idiopathic (unknown, usually with small kidneys), then diabetes mellitus. In both, glomerular damage and mesangial injury (causing metabolic and haemodynamic effects) occur. Mild- moderate essential hypertension does not cause CKD. Knowledge of the functional anatomy of the proximal tubule and loop of Henle is essential in understanding therapeutic targets and treatment of pathologies, as each region and transporter system has a key role. In brief, the journey of solutes from the blood to the production of urine occurs at five main anatomical sites— the glomerulus, the proximal tubule, the loop of Henle, the distal tubule (proximal part and distal part), and the collecting ducts (Figures 5.1 and 5.2). The glomerulus is a network of capillaries (like a ball of string), which merge with the nephron via Bowman’s capsule. It is the first site of filtration and the place where solutes, toxins, and small proteins are removed from the wider circulatory system, after delivery by the renal arteries (via an afferent arteriole). Blood and larger proteins remain in the arteriole and leave via an efferent branch, while the filtrate enters the proximal convoluted tubule. The afferent:efferent system ensures that a constant filtration pressure is maintained irrespective of variations in arterial pressure. The capillary bed is very large, so that permeability and filtration rates are high. A normal glomerular filtration rate (GFR) i.e. 90– 120 mL/ min/ 1.73 m<sup>2</sup>, depends on hydrostatic pressure, the colloid osmotic pressure and hydraulic per¬meability.
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Trinkaus, Erik, Alexandra P. Buzhilova, Maria B. Mednikova, and Maria V. Dobrovolskaya. "The Sunghir Human Hands." In The People of Sunghir. Oxford University Press, 2014. http://dx.doi.org/10.1093/oso/9780199381050.003.0016.
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As the interface between the body and technology, in all of its myriad forms, the skeletal hand morphology of Late Pleistocene humans has received increasing attention since the work of Sarasin (1932) and especially Musgrave (1970, 1971, 1973), as paleoanthropologists have documented a series of contrasts between archaic Homo and recent human hand bones (e.g., Vlček 1975; Trinkaus 1983b; Vandermeersch 1991; Niewoehner et al. 1997; Niewoehner 2001, 2008; Crevecoeur 2008; Lorenzo 2007; Trinkaus in press). However, since there were major changes in human technology between the Middle and Upper Paleolithic, and especially with the Mid Upper Paleolithic (MUP), the comparisons of concern should be between late archaic humans and early modern humans. For the Early Upper Paleolithic, the latter include relatively complete hand remains from Nazlet Khater 2 and scattered hand bones from Tianyuan 1 and Brassempouy (Henry-Gambier et al. 2004; Crevecoeur 2008; Shang and Trinkaus 2010). There are then relatively abundant hand remains from the MUP (Verneau 1906; Matiegka 1938; Mallegni et al. 1999; Sládek et al. 2000; Trinkaus 2006c; Trinkaus et al. 2010, 2014), including some immature ones (Mallegni and Parenti 1973; Sergi et al. 1974; Trinkaus et al. 2002b). Yet few of them have been described in detail. In this context, the Sunghir manual remains are described and select aspects are compared across Late Pleistocene samples (principally features that appear to change with the emergence of modern humans). For these descriptions and comparisons, the Sunghir 1 hand bones are paleontologically well preserved. Of the 54 bones potentially present for Sunghir 1 (not counting pollical sesamoid bones), 49 are known, and none sustained more than minor marginal erosion. The originally missing bones include one pisiform bone and four distal phalanges from the ulnar digits. During and after excavation, the right and left hands were mixed, so that the bones have been sorted based on morphology and (for the ulnar middle and distal phalanges) size.
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Cohen, Jonathan. "Sensory Substitution and Perceptual Emergence." In Sensory Substitution and Augmentation, edited by Fiona Macpherson, 205–35. British Academy, 2018. http://dx.doi.org/10.5871/bacad/9780197266441.003.0013.
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Designers of sensory substitution devices (SSDs) typically aim to capture a wide representational scope by requiring their devices to present in the substituting modality the full range of basic energy available to the substituted modality, and then using this information to code up any further representations needed. On this view, if we could build a device that represents to touch (say) the distal distribution of light intensity—the basic form of energy to which visual receptors are normally responsive—our device could, in principle, represent everything available to vision: colour, shape, form, motion, and so on. Unfortunately, I will argue, this simple idea fails. For perceptual modalities represent ‘emergent’ features —i.e. features whose exemplification is not fixed by the representation of the distribution of basic energy. Hence, an SSD whose basic representational vocabulary is limited to the distribution of such basic energy will leave things out. None of this shows that SSDs will inevitably fail to represent what sensory modalities normally represent. It does suggest, however, that if we want them to represent what sensory modalities normally represent, we will have to do more than preserve the representation of basic energy to which the substituted modalities are sensitive.
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Drapeau, Michelle S. M., and Colin G. Menter. "Ulna and radius." In Hominin Postcranial Remains from Sterkfontein, South Africa, 1936-1995, 65–98. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780197507667.003.0007.
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Descriptions of all radial and ulnar fossils from Sterkfontein are presented. The relatively large sample of forelimb bones from Sterkfontein provide information about the elbow, wrist, and forearm of Australopithecus africanus. The proximal orientation of the olecranon process and anterior orientation of the trochlear notch suggest that the forelimb was used in flexed position, as in humans. The bones are small relative to other hominins, and have relatively straight diaphysis and small muscle attachment markings like other australopiths, suggesting the presence of reduced forearm muscularity relative to apes. Diaphyseal cross-sectional shape suggests a pattern of forearm muscle use that may be neither completely human-like nor ape-like but somewhat intermediate, perhaps reflecting a reduced use in locomotion and an increased use in manipulation. In contrast to the diaphysis, the proximal radius is more clearly ape-like, with beveled heads and constricted and relatively long necks comparable to the Hadar specimens, which underscores the unique morphology of the elbow (neither completely human-like nor ape-like) in these hominins. The distal ulna, with the well-marked tendon groove, deep fovea, and a head shape intermediate between apes and humans, like A. afarensis specimens, suggest that stability was required during loading and use of the hand and wrist, although possibly less so than in extant apes. The overall picture of the Sterkfontein forelimb is that of a taxon that had powerful arms, but less powerful than apes, and that they were using them for tasks such as manipulation and probably less so for locomotion.
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Schumacher, Mark, and Beth B. Hogans. "Pain Pathways." In Pain Care Essentials, edited by Mark Schumacher and Beth B. Hogans, 7–25. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780199768912.003.0002.
Full textAbstract:
Chapter 1 describes the anatomic organization of the nervous system elements dedicated to sensing and perceiving pain: the so-called pain pathways or nociceptive processing system. This is a small part of the human nervous system that has a large impact on self-preservation as well as the potential to attenuate quality of life. The pain system is divided into four functional subsystems: transduction, dedicated to encoding information about noxious stimuli into the form of action potentials; transmission, which functions to carry pain information from distal structures such as toes to the spinal cord and brain; perception, which engages multiple areas of the cortex as well as subcortical structures to create an integrated awareness of pain; and modulation, which involves several different brain and spinal structures to potentially increase and decrease sensitivity and responses to painful stimulation. The development of the pain system is discussed in detail. This chapter provides the foundation for Chapter 2, which focuses on the relevant neurotransmitters and molecular signaling events involved in the major aspects of pain system functioning. Understanding pain structural pathways will often provide unique insight into a patient’s pain experience, provide clues regarding the cause of a patient’s pain, and yield insights into potentially effective treatments.
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Krueger, Robert F., and Daniel Goldman. "The Need for Dimensional Approaches in Discerning the Origins of Psychopathology." In Causality and Psychopathology. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199754649.003.0020.
Full textAbstract:
The 2008 meeting of the American Psychopathological Association was framed by a very challenging topic: causality. Indeed, setting aside any possible application in understanding psychopathology, causality is a deep concept—a fact that has kept philosophers gainfully employed for some time now. One thing is clear, however, at least in the behavioral sciences: If one wants to make credible causal claims, it helps to be able to directly manipulate the variables of interest. Indeed, some would go so far as to say that causality cannot be inferred without this kind of experimental manipulation. Through manipulation, one can systematically vary a variable of interest, while holding others constant, including the observational conditions. Consider, for example, how this is conveyed to new students in the behavioral sciences in a very useful text by Stanovich (2007). Stanovich (2007) first reviews the classic observation that simply knowing that two things (A and B) tend to occur together more often than one would expect by chance (a correlation) is not enough evidence to conclude that those two things have some sort of causal relationship (e.g., A causes B). To really claim that A causes B, ‘‘the investigator manipulates the variable hypothesized to be the cause and looks for an effect on the variable hypothesized to be the effect while holding all other variables constant by control and randomization’’ (p. 102). The implications of this experimental perspective on causality for psychopathology research are readily apparent: The situation is nearly hopeless, at least in terms of getting at the original, antecedent, distal causes of psychopathology. It is axiomatically unethical to manipulate variables to enhance the likelihood of psychopathology; we cannot directly manipulate things to create psychopathology in persons who do not already suffer from psychopathology. This is not to say that, once psychopathology is present, experimental designs are not fundamentally helpful in understanding the mechanisms underlying its expression. Indeed, the discipline of experimental psychopathology is founded on this premise, involving comparisons of the behaviors of persons with psychopathology and persons without psychopathology under precisely controlled conditions.
Conference papers on the topic "Distal-SO"
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Fomin, Vladimir, Vladimir Fomin, Ludmila Kharitonova, Ludmila Kharitonova, Dmitrii Alekseev, Dmitrii Alekseev, Elena Ivancha, and Elena Ivancha. "MORPHODYNAMICS OF THE BAKALSKAYA SPIT OF THE BLACK SEA." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b431521aa58.
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Studies of shape dynamics of the Bakalskaya Spit based on observation and numerical simulation are carries out. The Bakalskaya Spit is a dynamically active sand formation on the north-west coast of the Crimea Peninsula. Field observations and satellite image analyses showed that the erosion of spit west coast, eastward displacement of spit distal part and separation of distal part from the spit main part are the most significant processes. After the autumn storms in 2010 the isthmus between the distal part of spit and its main part was eroded and had not recovered till now. So the distal part of the Bakalskaya Spit turned into island. Dynamic of sediments depends on wind wave parameters and sea level oscillations. Effect of changing of wind wave direction and storm surge height on erosion and deposition processes in the Bakalskaya Spit region of the Black Sea is studied by using of XBeach numerical model. Dependencies of location and space dimension of erosion and deposition areas of sediments on characteristics of waves and surges are obtained. It is found that the most intensive erosion of spit isthmus occurs in case of wave running from the west in comparison of cases of wave running from the south-west and north-west if there are no surges. Presence of surges may results in increasing or decreasing of erosion process intensiveness depending on wave direction.
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Fomin, Vladimir, Vladimir Fomin, Ludmila Kharitonova, Ludmila Kharitonova, Dmitrii Alekseev, Dmitrii Alekseev, Elena Ivancha, and Elena Ivancha. "MORPHODYNAMICS OF THE BAKALSKAYA SPIT OF THE BLACK SEA." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b93fae199c8.45419382.
Full textAbstract:
Studies of shape dynamics of the Bakalskaya Spit based on observation and numerical simulation are carries out. The Bakalskaya Spit is a dynamically active sand formation on the north-west coast of the Crimea Peninsula. Field observations and satellite image analyses showed that the erosion of spit west coast, eastward displacement of spit distal part and separation of distal part from the spit main part are the most significant processes. After the autumn storms in 2010 the isthmus between the distal part of spit and its main part was eroded and had not recovered till now. So the distal part of the Bakalskaya Spit turned into island. Dynamic of sediments depends on wind wave parameters and sea level oscillations. Effect of changing of wind wave direction and storm surge height on erosion and deposition processes in the Bakalskaya Spit region of the Black Sea is studied by using of XBeach numerical model. Dependencies of location and space dimension of erosion and deposition areas of sediments on characteristics of waves and surges are obtained. It is found that the most intensive erosion of spit isthmus occurs in case of wave running from the west in comparison of cases of wave running from the south-west and north-west if there are no surges. Presence of surges may results in increasing or decreasing of erosion process intensiveness depending on wave direction.
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Qiao, Aike, and Teruo Matsuzawa. "Hemodynamics of End-to-End Femoral Bypass Graft." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-3125.
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In the conventional femoral bypassing operation, side-to-end (STE) configuration at the proximal anastomosis and end-to-side (ETS) configuration at the distal anastomosis are usually employed. With these configurations, blood flow from the bypass graft at the distal anastomosis strongly strikes on the floor of the host artery opposite the anastomosis. This will result in the violent variations of hemodynamics in the vicinity of distal anastomosis, and further bring about anastomotic intimal hyperplasia (IH) and restenosis. Consequently, the effectiveness of bypassing surgery is compromised in the medium and long term by the development of these pathological changes. It is widely accepted that hemodynamics is close correlated to the geometry configuration of femoral bypass graft. It is verified that flow field at the distal junction has more influences on the pathogenesis and its aftereffects are more critical because the development of IH and restenosis is prone to occur in that region and endangers the patency of subsequent arteries. Nonuniform hemodynamics, characterized by nonuniform Wall Shear Stress (WSS) and large sustained Wall Shear Stress Gradients (WSSG), is also commonly considered as one of the most important causes among the numerous complex physiological and biomechanical factors. Purpose of the present study is to investigate an alternative geometry configuration to improve the hemodynamics at the vicinity of distal anastomosis and increase the medium and long term patency rate of bypass graft surgery. According to the clinical observation, the stenosed host artery may become fully stenosed after bypassing surgery and the bypass graft is the only way to restore normal blood flow to ischemic limbs. The authors presented a modified bypassing configuration with an end-to-end (ETE) conjunction at the distal anastomosis. In this new model, the proximal graft is arc-shaped with STE junction and the distal graft is sinusoid-shaped with ETE junction. The bypass graft is of the same diameter of d = 8mm as the host femoral artery, so the graft can be connected with the femoral artery smoothly at the distal junction. The polytetrafluoroethylene (PTFE) is employed as the graft material. The blood is assumed to be an isotropic, homogeneous, incompressible, Newtonian continuum having a constant density and viscosity. The vessel walls are assumed to be rigid and impermeable. The blood flow is assumed to be physiologically pulsatile laminar flow. The mean Reynolds number is Rem = 204.7, Womersley number is α = 6.14. The boundary conditions include: the physiologically pulsatile entrance velocities at the inlet section, the no-slip boundary condition on the wall, the symmetric condition in the centerline plane of femoral and graft, and the outlet pressure condition with a reference pressure P = 0 at the exit section. Three-dimensional idealized femoral bypass graft model is developed and discretized. The blood flow in the proposed model is simulated with computational fluid dynamics (CFD) method using the finite element analysis. The temporal and spatial distributions of hemodynamics such as flow patterns and WSS in the vicinity of distal anastomosis during the cardiac cycle were analyzed. Especially, the emphasis here was on the analysis of WSS, the temporal and spatial WSSG and the Oscillating Shear Index (OSI). The simulation results indicated that: (1) the ETE model is featured with small secondary flow; (2) WSS at the distal anastomosis is uniform, WSSG is small, and OSI of the ETE model has not much changes compared with ETS graft. The present study showed that the femoral bypassing configuration with ETE bypass graft was of more favorable hemodynamics, and it could consequently improve the flow conditions and decrease the probability of IH and restenosis. With the consideration of that numerical simulation was proved to be of great help and guidance meaning for the biofluidmechanics research and the biomedical engineering, the results of the present study can be applied to medical device design and clinical treatment planning in addition to the application of computational methods to cardiovascular disease research.
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Eap, Laurent, and A. Sherif El-Gizawy. "Study on the Effects of Femoral Muscle Forces on Performance of Internal Fixation Devices Utilizing a Simulation Based Approach." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64926.
Full textAbstract:
Fractures of the distal femur are severe traumatic injuries that are treated with the utilization of internal fixation devices. Current preclinical device designs have primarily been investigated without observance of femoral muscle group effects — in addition to joint hip reaction forces — and irregular geometry of the human femora. This has led to a need to optimize the performance and fit of internal fixation devices to produce maximal reliability and structural integrity. The present study utilizes a systematic design approach that employs computer-aided modeling, robust design methodology, finite element methods, and optimization processes for a femoral locking plate system. In doing so, a computer-aided model was constructed to illustrate a distal femoral fracture fixation system. Femoral muscle force directions and magnitudes associated with a normal walking gait cycle were inputted into the system to simulate realistic loading conditions. In conjunction with finite element methods, the model was used to assess stress and strain distributions along the femur, femoral plate, and screws. Subsequently, optimization processes were then employed to assess the effects of varying device geometric parameters and bone topology on the bone-implant stress distributions and overall device design. The proposed simulation-based optimization process was able to yield a more accurate representation of the biomechanics within the bone-implant interaction by taking into consideration the substantial effects of femoral muscle groups. In doing so, a robust device design is developed which improves overall performance via minimizing weight and maximizing overall factor of safety.
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Cronin, James A., Mary Frecker, and Abraham Mathew. "Design of a Compliant Endoscopic Suturing Instrument." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34832.
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This paper outlines the development and initial optimization of a compliant endoscopic suturing instrument. The developing field of Natural Orifice Transluminal Endoscopic Surgery requires innovative instruments to meet the size limitations inherent in this type of minimally invasive surgery; using compliant mechanisms is proposed as one method of meeting this requirement. Three initial compliant designs were created, modeled, and compared for a distal opening of 10 mm. Restricting these designs so that they must fit within a 3.3 mm working channel is currently unique in endoscopic suturing instruments. A design that utilizes contact for stress relief and intertwining parts for added deflection was selected from the three. ANSYS® was used to aid in graphical optimization to maximize the jaw opening and maximize the puncture force of the selected design. The best geometry has a distal opening of 13.8 mm at the tips and can supply a puncturing force of 6.33 N. A prototype has been machined using the optimized dimensions and is ready to be tested. This initial study in compliant suturing instrument designs has revealed response patterns for the chosen geometries that will lead to further refinements and improvements in future models.
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Eia, Maren Eriksen, Elise Mari Vigre, and Thorstein Ravneberg Rykkje. "Modeling a Knuckle-Boom Crane Control to Reduce Pendulum Motion Using the Moving Frame Method." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10436.
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Abstract A Knuckle Boom Crane is a pedestal-mounted, slew-bearing crane with a joint in the middle of the distal arm; i.e. boom. This distal boom articulates at the ‘knuckle (i.e.: joint)’ and that allows it to fold back like a finger. This is an ideal configuration for a crane on a ship where storage space is a premium. This project researches the motion and control of a ship mounted knuckle boom crane to minimize the pendulum motion of a hanging load. To do this, the project leverages the Moving Frame Method (MFM). The MFM draws upon Lie group theory — SO(3) and SE(3) — and Cartan’s Moving Frames. This, together with a compact notation from geometrical physics, makes it possible to extract the equations of motion, expeditiously. The work reported here accounts for the masses and geometry of all components, interactive motor couples and prepares for buoyancy forces and added mass on the ship. The equations of motion are solved numerically using a 4th order Runge Kutta (RK4), while solving for the rotation matrix for the ship using the Cayley-Hamilton theorem and Rodriguez’s formula for each timestep. This work displays the motion on 3D web pages, viewable on mobile devices.
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Campos, Lucas, Francis Bourbonnais, Ilian A. Bonev, and Pascal Bigras. "Development of a Five-Bar Parallel Robot With Large Workspace." In ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28962.
Full textAbstract:
Five-bar planar parallel robots for pick and place operations are always designed so that their singularity loci are significantly reduced. In these robots, the length of the proximal links is different from the length of the distal links. As a consequence, the workspace of the robot is significantly limited, since there are holes in it. In contrast, we propose a design in which all four links have equal lengths. Since such a design leads to more parallel singularities, a strategy for avoiding them by switching working modes is proposed. As a result, the usable workspace of the robot is significantly increased. The idea has been implemented on an industrial-grade prototype and the latter is described in detail.
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Liddle, Kate D., Meir Marmor, Hyun Kyu Han, Marshall Fong, Thomas Chu, Viva Tai, Kathleen Mulligan, Jenni M. Buckley, and Amir Matityahu. "Predicting the Strength of Volar Screw Purchase in the Distal Radius: Comparison Between DEXA and a New “Smart” Surgical Tool." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19086.
Full textAbstract:
The distal radius is a common site of fracture with volar plates and screws as the current clinical practice for fracture fixation [1]. Local measurements of bone quality at the sites of screw insertion aid in providing the most stable fixation with the least amount of hardware, minimizing the risk of construct failure and irritation to soft tissue [2, 3]. The clinical standard for pre-operative bone mineral density (BMD) assessment uses dual x-ray absorptiometry (DEXA). However, DEXA scans provide global BMD values and cannot accurately predict variations in BMD within a given anatomical site [4]. Furthermore, patients frequently present without a pre-operative DEXA scan, so intra-operative assessment would be ideal. We developed a simple sensor system that would be appropriate for assessing local BMD intra-operatively. The system consists of a “smart” Weber clamp instrumented with a single uniaxial strain gage that provides real-time feedback regarding the local BMD.
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Parsa, Soheil S., Juan A. Carretero, and Roger Boudreau. "Example of Internal Redundancy to Improve the Dynamics Performance of Parallel Manipulators." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-70536.
Full textAbstract:
In recent years, redundancy in parallel manipulators has been discussed for the cases of kinematic, actuation and branch redundancy. Some advantages of these redundant manipulators include the reduction or elimination of some types of kinematic singularities and/or an increase of their reachable and dexterous workspaces, to name a few. Internal redundancy, first introduced for serial manipulators, refers to the concept of adding movable masses to some links so as to allow to control the center of mass and other dynamic properties of some links. In this paper, the concept of internal redundancy is investigated for the first time in the context of parallel manipulators. More specifically, the 3-RRR planar manipulator, where a movable mass has been added to the distal link, is analysed. The manipulator’s dynamic model is briefly introduced and then is used to track a simple trajectory. A numerical example is shown to support the idea.
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Kim, Yong Hyun, Joon Sand Lee, and Xin Wu. "Numerical Simulation of Fluid-Induced Vibration and Wall Shear Stress in Fusi/Form Cerebral Aneurysm: Newtonian and Non-Newtonian Fluid." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14766.
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Vascular techniques have been used for curing the aneurysm, but the reason for the occurrence of aneurysms can not be known using these techniques. These techniques are usually used for preventing a significant situation such as rupture of an aneurysm. In our study, blood flow effects with or without vascular techniques inside an aneurysm were analyzed with computational fluid dynamics (CFD). Important hemodynamic quantities like wall shear stress and pressure in vessel are difficult to measure in-vivo. Blood flow is assumed to be Newtonian fluid. But it actually consists of platelets, so it is also considered a non-Newtonian fluid in this study. Results of the numerical model were used to compare and analyze fluid characteristics with experimental data. Using the flow characteristics (wall shear stress (WSS), wall shear stress gradient (WSSG)), the rupture area was identified to be located in the distal area. However, the rupture area, in vivo studies, was observed to be present at a different location. During pulsatile flow, vibration induced by flow is implicated by weakening of the artery wall and affects more than shear stress. After adapting the fluid-induced vibration, the rupture area in aneurysm is found to be located in the same area as the in-vivo result. Since smaller inflow and low WSS provide the effect of the distal neck, the vibration provides more effects in dome area. In this study it has been found that the effect of shear stress on the rupture of aneurysm is less than the effect of vibration. In the case of non-Newtonian fluid, vibration induced by flow also has more effects than WSS and WSSG. The simulation results gave detailed information about hemodynamics under physiological pulsatile inlet condition.