Venous types

Two types of Protein S deficiency have been described. In type I deficiency there is tittle to no free Protein S but normal amounts of bound Protein S are present. In type II Protein S deficiency both free and bound Protein S are very low to absent. Deficiency of free Protein S is associated with venous and arterial thrombosis. 

Located in close proximity to the primary capillary plexus in the hypothalamus are specialized neurosecretory cells. In fact, the axons of these cells terminate on the capillaries. The neurosecretory cells synthesize two types of hormones releasing hormones and inhibiting hormones (see Table 10.2). Each of these hormones helps to regulate the release of a particular hormone from the adenohypophysis. For example, thyrotropin-releasing hormone produced by the neurosecretory cells of the hypothalamus stimulates secretion of thyrotropin from the thyrotrope cells of the adenohypophysis. The hypo-thalamic-releasing hormone is picked up by the primary capillary plexus travels through the hypothalamic-hypophyseal portal veins to the anterior pituitary leaves the blood by way of the secondary capillary plexus and exerts its effect on the appropriate cells of the adenohypophysis. The hypophyseal hormone, in this case, thyrotropin, is then picked up by the secondary capillary plexus, removed from the pituitary by the venous blood, and delivered to its target tissue. 

The sympathetic system also innervates vascular smooth muscle and regulates the radius of the blood vessels. All types of blood vessels except capillaries are innervated however, the most densely innervated vessels include arterioles and veins. An increase in sympathetic stimulation of vascular smooth muscle causes vasoconstriction and a decrease in stimulation causes vasodilation. Constriction of arterioles causes an increase in TPR and therefore MAP. Constriction of veins causes an increase in venous return (VR) which increases end-diastolic volume (EDV), SV (Frank-Starling law of the heart), CO, and MAP. 

Nesiritide is manufactured using recombinant techniques and is identical to the endogenous B-type natriuretic peptide secreted by the ventricular myocardium in response to volume overload. Consequently, nesiritide mimics the vasodilatory and natriuretic actions of the endogenous peptide, resulting in venous and arterial vasodilation increases in cardiac output natriuresis and diuresis and decreased cardiac filling pressures, sympathetic nervous system activity, and renin-angiotensin-aldosterone system activity. 

Thrombosis is the other phenomenon that crucially contributes to both the arterial and the venous forms of CVD, although the type of thrombus,... 

Currently, in both arterial and venous occlusion, newer products such as alteplase which is recombinant human tissue-type plasminogen activator where 10 mg is given as an intitial bolus and a further 90 mg infused over 2 hours are offering alternative regimens. Although costly they have apparent benefit in stroke and acute coronary syndromes. 

The biologic actions of kinins are mediated by specific receptors located on the membranes of the target tissues. Two types of kinin receptors, termed Bj and B2, have been defined based on the rank orders of agonist potencies. (Note that here stands for bradykinin, not for -adrenoceptor.) Bradykinin displays the highest affinity in most B2 receptor systems, followed by lys-bradykinin and then by met-lys-bradykinin. One exception is the B2 receptor that mediates contraction of venous smooth muscle this appears to be most sensitive to lys-bradykinin. Recent evidence suggests the existence of two B2-receptor subtypes, which have been termed B2A and B2B. 

A hollow-fiber-type membrane blood oxygenator, in which blood flows inside the hollow fibers, has a total membrane area (outside fibers) of 4.3 m". The inside diameter, membrane thickness, and length of the hollow fibers are 200 pm, 25 pm, and 13 cm, respectively. When venous blood (Ht = 40%, pQ. = 36 mmHg)... 

Among the inhibition of other types of enzymes, several representatives of the class of (3-lactams have been found to effectively inhibit proteases. 2-Azetidinones tetrasubstituted have also been identified as powerful and selective inhibitors of thrombin, a serine protease involved in both venous and arterial thrombotic episodes. Analogous compounds have also been found to display inhibition towards tryptase. 

A 39-year-old man developed type 1 diabetes and lost 9 kg over 6 months (115). He was treated with intravenous fluids and insulin. Within 1 month he developed bilateral edema to the knees. The jugular venous pressure was not raised. 

In addition to these traditional vasodilators, nesir-itide (Natrecor) was developed as a newer method for producing arterial and venous dilation in people with heart failure.58 This substance was derived from human B-type natriuretic peptide (BNP) using recombinant DNA techniques. BNP is a naturally occurring substance that is released from the ventricles when the heart is subjected to increased blood volume and pressure.12 This substance dilates peripheral arteries and veins, thus reducing cardiac afterload and preload, respectively. Hence, nesiritide can be administered intravenously to reduce cardiac workload in certain patients with severe or acute heart failure.12,58... 

The use of traditional (unffactionated) heparin has therefore been replaced by LMWHs to a large extent.18,100 LMWHs are clearly safer and more convenient to their unfractionated counterparts, and these drugs have become the primary method of treating acute venous thrombosis.47,100 LMWHs are now used routinely to prevent or treat deep vein thrombosis (DVT) following various types of surgery or medical conditions (ischemic stroke, cancer).70,127 It has also been suggested that LMWHs will produce optimal effects if they are administered for more than a few days, and some patients who are at high risk for thrombosis may receive LMWHs via subcutaneous injection for several weeks or months.80 Future research will help determine the best way to use LMWHs to prevent or treat venous thrombosis in specific clinical situations. 

Finally, thrombolytic drugs are gaining acceptance in treating other types of arterial and venous occlusion. For example, thrombolytic therapy can help dissolve clots in peripheral arteries (femoral, popliteal, and so forth)56 these drugs can help resolve thrombus formation in the large veins (DVT).68 This treatment... 

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