Arteries Media

The largest cause of morbidity and mortality comes from involvement of the vascular system, particularly from thromboembolic events which can occur in both arteries and veins and in all sizes of vessels [6], Thrombophlebitis and pulmonary embolism are the most frequent vascular accidents, whereas thromboses of large and medium arteries, especially carotid and renal arteries, are frequent causes of death [7]. Ischemic heart disease is less common. Nenroimaging may demonstrate evidence of infarction or thrombosis. Association with other genotypes linked to increased risk of vascular disease, such as factor V Leiden and thermola-bile methylenetetrahydrofolate reductase, may increase the risk of thrombosis in individuals with homocystinuria [17, 18]. 

Two different circulatory systems, the bronchial and the pulmonary, supply the lungs with blood [133], The bronchial circulation is a part of the systemic circulation and is under high pressure. It receives about 1% of the cardiac output and supplies the conducting airways, pulmonary blood vessels and lymph nodes [133], It is important for the distribution of systemically administered drugs to the airways and to the absorption of inhaled drugs from the airways [18]. The pulmonary circulation comprises an extensive low-pressure vascular bed, which receives the entire cardiac output. It perfuses the alveolar capillaries to secure efficient gas exchange and supplies nutrients to the alveolar walls. Anastomoses between bronchial and pulmonary arterial circulations have been found in the walls of medium-sized bronchi and bronchioles [18, 65, 67],... 

An isolated mammalian heart whose extrinsic nervous connections have been severed will beat spontaneously for hours if it is supplied with a nutrient medium via the aortic trunk and coronary arteries (Langendorff preparation). In such a preparation, only those drugs that act directly on cardio-myocytes will alter contractile force and beating rate. 

However, unlike atherogenic low-density lipoproteins and very low-density lipoproteins, which when metabolized release cholesterol that is in the form of esters and is deposited in tissue, chylomicrons and high-density lipoproteins are not atherogenic. There is a direct link between the concentration of high-density lipoproteins in blood plasma and expressed atherosclerotic changes in medium and large arteries. 

Arterial thrombi (white thrombi) are formed initially from both platelets and fibrin in medium-sized arteries on the basis of atherosclerosis. These thrombi can lead to symptoms of, among others, myocardial ischemia and myocardial infarction. The treatment is primarily aimed at prevention of thrombus formation with platelet aggregation inhibitors. For the treatment of myocardial infarction thrombolytic agents are used and for secondary prevention both oral anticoagulants and anti-platelet drugs are employed. 

Anti-atherosclerotic. Preventing the formation of plaques containing cholesterol, lipoid material, and lipophages within the intima and inner media of large- and medium-sized arteries. 

Besides the paranoid psychosis associated with chronic use of amphetamines, a specific lesion associated with chronic amphetamine use is necrotizing arteritis, which may involve many small and medium-sized arteries and lead to fatal brain hemorrhage or renal failure. Overdoses of amphetamines are rarely fatal they can usually be managed by sedating the patient with benzodiazepines. 

Dog No. 3 was omitted because of insufficient data. It is apparent that a marked uptake of ammonia occurs in tissues in metabolic acidosis. In alkalosis the uptake by tissues is only slightly greater than normal, and the arterial levels of ammonia are comparable with normal values. The elevation of blood ammonia which occurs on vigorous acidification of the animal might not be due to a drop in permeability with pH, but might be due to a phenomenon reported by Krebs and Henseleit (K4). Urea synthesis by liver slices is directly proportional to the pH and C02 content of the medium. Table 2, constructed from data reported in this paper, shows this dependence. 

Platelet-collagen interactions are believed to have the greatest significance at the medium and high shear rates found in arteries and diseased vessels. The binding between immobilized vWF and GPIb/IX/V is reversible and slows the... 

Digital x rays can be modified electronically to increase contrast, display certain structures in color or three dimensions, or subtract areas that interfere, allowing clearer pictures of structures such as veins and arteries. Very small differences in density may be amplified for even clearer viewing. This may be important in cases in which a contrast medium is injected into veins or arteries enhancing small differences allows the use of smaller amounts of the contrast medium, lessening the danger to patients. 

Takayasu arteritis affects medium-sized and large arteries, specifically the aorta and the supraaortic branches. The disease is usually not seen in intracranial vessels nor in the temporal artery. Although for a long time DSA was accepted as a diagnostic... 

Primary angiitis of the CNS causes inflammation particularly in small leptomeningeal vessels, whereas larger vessels can also be affected. Systemic variants of vasculitis and secondary arteritis of the CNS affect mostly small or medium-sized arteries to different degrees, and occasionally the venous system is also afflicted as in Behcet disease. Segmental stenoses are frequently found, often not including bifurcations and alternating with arterial dilatations. This pattern is not definitively specific and can also be seen in atherosclerosis. Even with an optimal MRA technique, DSA still remains necessary for the depiction of tiny vessel lesions (Fig. 5.26). 

Many causes of acute spinal cord infarction (of arterial and venous origin) have been reported (Table 17.2). They include diseases of the aorta and aortic surgery, thromboembolic events and cartilaginous disc embolism, vasculitis, coagulopathy, radiation-induced vasculopathy, toxic effects of contrast medium, epidural anesthesia, periradicu-lar nerve root therapy with crystalline corticoids, decompression illness, shock or cardiac arrest, lumbar artery compression and other etiologies... 

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