Anatomy vascular

The proposal that NO or its reactant products mediate toxicity in the brain remains controversial in part because of the use of non-selective agents such as those listed above that block NO formation in neuronal, glial, and vascular compartments. Nevertheless, a major area of research has been into the potential role of NO in neuronal excitotoxicity. Functional deficits following cerebral ischaemia are consistently reduced by blockers of NOS and in mutant mice deficient in NOS activity, infarct volumes were significantly smaller one to three days after cerebral artery occlusion, and the neurological deficits were less than those in normal mice. Changes in blood flow or vascular anatomy did not account for these differences. By contrast, infarct size in the mutant became larger... 

A related idea is that peripheral nerves are the source of the problem and then cause the associated vascular changes via release of 5-HT and other inflammatory mediators. The observation that the changes in the vasculature do not follow vascular anatomy has led to a new theory, that of spreading depression . Here, the primary abnormality is... 

Stevens, E.D., Lam, H.M. and Kendall, J. (1974). Vascular anatomy of the counter-current heat exchanger of skipjack tuna. Journal of Experimental Biology 61,145-153. 

Additional factors influence the extent of the final infarction. The speed of obstruction may allow collateral arteries to develop, if it occurs gradually (Busch et al. 2003), whereas complete sudden blockade of a major artery by an embolus leaves only some minutes to activate sufficient collateral flow. Hypoxia, hyperglycemia, acidosis, fever, hypotonia, and normal or abnormal variants in vascular anatomy my contribute to the resulting infarction (Hossmann 1999). Basically, the loss of oxygen and... 

Preliminary studies of collateral circulation in high grade stenoses or occlusions using ultra fast dynamic MRA with temporal resolution in the range of a second did show delayed contrast enhancement in the affected vascular territory, but did not provide relevant additional information compared with conventional MRI and perfusion techniques probably due to the reduced spatial resolution (Wetzel et al. 2001). A dedicated analysis of collateral circulations, especially extra-intracranially, is still the domain of DSA as far as the exact depiction of anatomical connections is of importance. If the exact anastomotic vascular anatomy is not of primary interest, the collateral supply is better determined by MR perfusion techniques. 

Vascular Anatomy. One aspect of the translocation system that is often overlooked is the influence of the structural features of the plant s vascular system on solute transport. For example, although much of what is known about phloem loading has been derived from a few dicotyledon leaves, all dicotyledon leaves are not similar. A notable example is the soybean leaf. Soybean leaves are specialized in that they have a unique cell type called the paraveinal mesophyll... 

Tarin, D. and Price, J. E. (1981). Influence of microenvironment and vascular anatomy on metastatic colonization potential of mammary tumors. Cancer Res. 41, 3604-3609. 

Nagabhusan, G., Acharya, S.K., Joshi, Y.K., Nundy, S., Tandon, B.N. Ultrasonography in portal hypertension a sensitive noninvasive test to demonstrate portal-vascular anatomy. Gastroenterol. Jpn. 1989 24 442-445... 

Figure 13-16 Same patient as shown in Figure 13-15. A cerebral arteriogram was performed to delineate the vascular anatomy of the patient s AVM. In this case, a digital subtraction technique was used in which digital images obtained prior to injection of the contrast agent were subtracted from the contrast agent images by computer...

An additional variable that must be accounted for in derma absorption studies that may overshadow the difference between chemicals Is body site differences in absorption within a species. Regional variation in skin permeability at different body. sites may be related to skin thickne.ss, number of cell layers, cell size of the epidermis and stratum comeum, and di.stribution of hair follicles and sweat pores. Because of thick layers of stratum corneum, permeability in palmar and plantar skin is expected to be less than that in the scalp or forearm (Feldmann and Maibach, 1974). Data from several studies suggc.st that regional variation in vascular anatomy and blood flow should also be considered (Montciro-Rivicrc o/.. 1990 Qiao cf a/.. 1993). 

Stress-free and unloaded reference configurations Muscle fiber architecture Connective tissue organization Pericardium, epicardium, and endocardium Coronary vascular anatomy... 

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