Vascular tissues

COX-2 synthesises PGI2 (prostacyclin) and the high incidence of myocardial infarctions with selective COX-2 inhibitors has been attributed to inhibition of COX-2 in vascular tissues. Prostacyclin, made by blood vessel walls, inhibits aggregation of platelets and maintains a balance with thromboxane. Thromboxane, which is released by platelets, promotes clotting. Prostacyclin is synthesised mostly by COX-1, but in humans selective COX-2 inhibition reduces its biosynthesis in vivo. This reduced synthesis may lead to an overactive thromboxane system and increased risk of thromboembolism. 

BolweU, G.P. and Northcote, D.H. (1981) Control of hemiccllulose and pectin synthesis during differentiation of vascular tissue in bean (Phaseolus vulgaris) caUus and in bean hypocotyl. Planta, 152 225-233. 

Niacin (vitamin B3) has broad applications in the treatment of lipid disorders when used at higher doses than those used as a nutritional supplement. Niacin inhibits fatty acid release from adipose tissue and inhibits fatty acid and triglyceride production in liver cells. This results in an increased intracellular degradation of apolipoprotein B, and in turn, a reduction in the number of VLDL particles secreted (Fig. 9-4). The lower VLDL levels and the lower triglyceride content in these particles leads to an overall reduction in LDL cholesterol as well as a decrease in the number of small, dense LDL particles. Niacin also reduces the uptake of HDL-apolipoprotein A1 particles and increases uptake of cholesterol esters by the liver, thus improving the efficiency of reverse cholesterol transport between HDL particles and vascular tissue (Fig. 9-4). Niacin is indicated for patients with elevated triglycerides, low HDL cholesterol, and elevated LDL cholesterol.3... 

The increased serum phosphorus binds to calcium in the serum, which leads to deposition of hydroxyapatite crystals throughout the body. The calcium-phosphorus (Ca-P) product reflects serum solubility. A Ca-P product greater than 75 mg2/dL2 promotes crystal deposition in the joints and eye, leading to arthritis and conjunctivitis, respectively. Soft tissue deposition primarily affects the coronary arteries of the heart, lungs, and vascular tissue and is associated with a Ca-P product greater than 55 mg2/dL2.36 The Ca-P product has been associated with increased mortality37 and is a risk factor for calcification of vascular and soft tissues.35... 

For example, lignin fluorescence in roots, vascular tissues, and cell walls of aerial plant parts interferes with imaging at wavelengths between 490 and 620 nm while the chlorophyll autofluorescence in leaves and stems is most problematic between 630 and 770 nm. Thus imaging of GFP and its closest spectral variants such as CFP and YFP is most likely to be problematic in roots, whereas RFPs may be hard to discriminate in chloroplast containing aerial plant tissues [17], These problems have only recently been effectively... 

FIGURE 8.8 H2S production in vascular tissues. IPS production by aorta homogenate (upper panel), cultured rat vascular smooth muscle cells (VSMCs middle panel), and intact rat aorta occurs after the addition of substrate L-cysteine (L-cys) and cofactor pyridoxal L-phosphate (PLP) for the enzyme CGL located in vascular tissue. H2S production is inhibited after the CGL. 3 cyano-L-alanine (BCA) is added. Ferric Lucina pectinata hemoglobin I (metHb) is added to confirm H2S production. The quantity of metHb-sulfide produced, determined spectrophotometrically, matched the levels of H2S detected by the PHSS (after [41]). 

The seeds of dicotyledonous plants have two cotyledons, or seed leaves, which are part of the embryo. The cotyledons usually are the main storage tissue, although in some plants (such as castor bean) the endosperm also has a storage function. During development in the field, seeds gradually accumulate storage oils, proteins and carbohydrates (Table 3.1). In the seed, the cotyledon structure is relatively simple. The remainder of the embryo, the embryonic axis, consists mostly of undifferentiated cells, but provascular tissue can be detected that develops into vascular tissue in the seedling. 

CL produced in the presence of exogenous NADPH or NADH, which has been studied in Refs. [97,100], may originate from other sources than superoxide generation [90]. In our opinion [98], the data obtained on the basis lucigenin CL measurement, especially with the use of small lucigenin concentrations provide the reliable estimate of superoxide concentration while the use of ESR spin technique underestimates it, particularly in vascular tissue and cells (see Chapter 32). 

O Donnell et al. [70] found that LOX and not cyclooxygenase, cytochrome P-450, NO synthase, NADPH oxidase, xanthine oxidase, ribonucleotide reductase, or mitochondrial respiratory chain is responsible for TNF-a-mediated apoptosis of murine fibrosarcoma cells. 15-LOX activity was found to increase sharply in heart, lung, and vascular tissues of rabbits by hypercholesterolemia [71], Schnurr et al. [72] demonstrated that there is an inverse regulation of 12/15-LOXs and phospholipid hydroperoxide glutathione peroxidases in cells, which balanced the intracellular concentration of oxidized lipids. 

Signs Initially, leaves may have a thin white line but eventually become slightly yellowed (chlorotic). The vascular tissue is damaged and leaves begin to die from the edges towards the midrib, ultimately resulting in plant death. It has the capacity to destroy whole fields in a few months. ... 

There are seven membrane forms of GC, designated GC-A to GC-G [33], Two forms, GC-A and GC-B (Mr = 120kDa), serve as receptors for atrial natriuretic peptide (ANP) and related peptides. ANP is a 28-amino-acid peptide isolated originally from cardiac atria as an important factor in the regulation of sodium excretion and blood pressure. GC-A binds ANP, as well as brain natriuretic peptide (BNP), and is located in vascular tissue and kidney. 

Other examples of PDE inhibitors with possible clinical usefulness are inhibitors of PDE3 or PDE4 (Table 21-1). Based on the localization of PDE3 to heart and vascular tissue and the role of cAMP in regulating heart muscle contraction and smooth muscle relaxation, a large number of PDE3 inhibitors have been developed for possible clinical applications in cardiovascular medicine. 

Phosphodiesterase inhibitors are selective for isoenzyme type 5 in genital tissue. Inhibition of this isoenzyme in nongenital tissues (e.g., peripheral vascular tissue, tracheal smooth muscle, and platelets) can produce adverse effects. 

Most interesting in this light are our initial experiments on mouse bladder showing the absolute dependence of [i adrenergic relaxation in the bladder to the presence of PLB. Isoproterenol or forskolin activation of the A -kinase pathway led to complete relaxation of bladder from wild type mice, with little or no response in the PLB knockout bladder (K. Nobe R. J. Paul, unpublished observations). On the other hand, relaxation via G -kinase pathway activation was identical in the PLB knockout and wild-type bladder. PLB modulation of SR appears to be the dominant pathway for A-kinase mediated relaxation in mouse bladder in contrast to its lesser role in this pathway for the vascular tissues studied. 

Paul This is particularly the case in vascular tissue where this suppression can be maintained for hours. We have to get back to the calculation of how much the SR can hold. When I did the KC1 contractions, my expectation was that I would saturate the SR in a reasonable period of time that it couldn t take up any more Ca2+ because it would be self-inhibited. This was going to be my control. It was both disappointing and exciting to find out that the shift was maintained and disappeared with CPA. I am going back to the sort of vectorial unloading... 

R., Peterson, T. E., Harrison, D. G., Nitroglycerin metabolism in vascular tissue role of glutathione transferases and relationship between NO and N02 formation. Biochem. J. 292... 

Bornfeldt, K. E., Axelsson, K. L., Studies on the effect of different inhibitors of arachidonic acid metabolism on glyceryl trinitrite-induced relaxation and cGMP elevation in bovine vascular tissue. Pharmacol. Toxicol. 60 (1987),... 

Ascorbic acid [71] and vitamin E [72] are powerful scavengers of reactive oxygen species and are known to enhance the sensitivity of vascular tissue to organic nitrates. Also the local concentration of NO due to administration of GTN is greatly enhanced by hypoxia [73]. 

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