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Posted: Wed Mar 25, 2009 8:01 am
by cheerleader
marcstck wrote:
I find it striking, though, that the PPMS patients studied all were afflicted with the same type of lesion, and that that lesion type did not show up in any other flavor of MS.
Me too, Marc. I found it interesting that Pattern IV lesion, the type found in PPMS, is more the type of lesion from from a "viral, toxic or ischemic attack", and not related to the relapsing/remitting autoimmune form of lesions shown in patterns I and II. Looking at it from the venous insufficiency paradigm (as I'm doing lately), I can see Pattern IV as result of an unrelenting vein blockage....which does not allow from drainage and repair. The CNS is under continual attack from reflux and remyelination is not possible.
AC
Posted: Wed Mar 25, 2009 9:40 am
by jimmylegs
i wiki'ed ischemia to see what it had to say:
Consequences
Since oxygen is mainly bound to hemoglobin in red blood cells, insufficient blood supply causes tissue to become hypoxic, or, if no oxygen is supplied at all, anoxic. This can cause oncosis (i.e. cell death by lysis). In very aerobic tissues such as heart and brain, at body temperature necrosis due to ischemia usually takes about 3-4 hours before becoming irreversible. This and typically some collateral circulation to the ischemic area accounts for the efficacy of "clot-buster" drugs such as Alteplase, given for stroke and heart attack within this time period. However, complete cessation of oxygenation of such organs for more than 20 minutes typically results in irreversible damage.
Ischemia is a feature of heart diseases, transient ischemic attacks, cerebrovascular accidents, ruptured arteriovenous malformations, and peripheral artery occlusive disease. The heart, the kidneys, and the brain are among the organs that are the most sensitive to inadequate blood supply. Ischemia in brain tissue, for example due to stroke or head injury, causes a process called the ischemic cascade to be unleashed, in which proteolytic enzymes, reactive oxygen species, and other harmful chemicals damage and may ultimately kill brain tissue.
Restoration of blood flow after a period of ischemia can actually be more damaging than the ischemia. Reintroduction of oxygen causes a greater production of damaging free radicals, resulting in reperfusion injury. With reperfusion injury, necrosis can be greatly accelerated.
Posted: Fri Mar 27, 2009 7:48 am
by peekaboo
Since I am an PPMSr I havemy homework to do...Read all the links provied in this thread...thanks