Intravascular enhancement

Several investigators have described the time course of contrast enhancement with gadolinium chelate in patients with ischemic stroke (Crain et al. 1991 Elster 1991 Essig et al. 1996 Karonen et al. 2001 Vo et al. 2003). Contrast-enhanced MRI on days 1, 2 and 7 post-stroke revealed two different patterns, namely intravascular and parenchymal enhancement of the contrast agent. Whereas intravascular enhancement in the infarcted area was detected in 78% of the cases on day 1 and in 30% of cases at 1 week, parenchymal enhancement was observed with increasing frequency over 7 days (Karonen et al. 2001). 

An intravenous infusion of PAF causes rapid (within 60 s) intravascular platelet aggregation, thrombocytopenia and platelet factor 4 release, as well as a profound and reversible neutropenia, due to enhanced aggregation and adherence of these cells. In vitro, PAF effects on neutrophils are dependent upon extracellular Ca2+ and Mg2+ and occur within 60 s of addition. The addition of inhibitors of 5-lipoxygenase activity (e.g. ETYA, 5,8,11,14-eicosatetraenoic acid and NDGA, nordihydroguaiaretic acid) - but not those... 

Demos, S.M., H. Alkan-Onyuksel, B.J. Kane, K. Ramani, A. Nagaraj, R. Greene, M. Klegerman, and D.D. McPherson, In vivo targeting of acoustically reflective liposomes for intravascular and transvascidar ultrasonic enhancement. J Am Coll Cardiol, 1999. 33(3) 867-75. 

See Table 15-6. Potassium-sparing diuretics are most useful in states of mineralocorticoid excess or hyperaldosteronism (also called aldosteronism), due either to primary hypersecretion (Conn s syndrome, ectopic adrenocorticotropic hormone production) or secondary hyperaldosteronism (evoked by heart failure, hepatic cirrhosis, nephrotic syndrome, or other conditions associated with diminished effective intravascular volume). Use of diuretics such as thiazides or loop agents can cause or exacerbate volume contraction and may cause secondary hyperaldosteronism. In the setting of enhanced mineralocorticoid secretion and excessive delivery of Na+ to distal nephron sites, renal K+ wasting occurs. Potassium-sparing diuretics of either type may be used in this setting to blunt the K+ secretory response. 

Greater use of nonionic contrast media for routine X-ray procedures is clearly the trend of the future. It was estimated that in 1991, approximately 69% of the procedures performed in the United States used nonionic contrast media compared to about 66% in Europe and more than 80%in Japan. In 1994 the percentage increased to about 80% in the United States, 75% in Europe, and 92%in Japan (540). In the United States, in 1994 as many as 18 million patients received intravascular contrast media, and an estimated 170 million contrast medium-enhanced radiologic studies were performed from 1978 to 1994 (541). 

---