Fibrinogen, carbohydrate

These hormones also have profound effects on the function of the liver. Some of these effects are deleterious and will be considered below in the section on adverse effects. The effects on serum proteins result from the effects of the estrogens on the synthesis of the various 2 globulins and fibrinogen. Serum haptoglobins produced in the liver are depressed rather than increased by estrogen. Some of the effects on carbohydrate and lipid metabolism are probably influenced by changes in liver metabolism (see below). 

The first reason is theoretical. The demonstrated effects of the new substances and combinations on lipids and carbohydrates do not have any major relevance to the thromboembolic process. The latter is linked primarily to changes in the hemostatic system and blood coagulation, involving platelet aggregation, coagulation factors, fibrinogen concentrations, and blood viscosity. 

Fig. 2. Schematic diagram of the three pairs of polypeptide chains of fibrinogen. The Aa, B/3, and 7 chains are represented by bars with lengths proportional to the number of amino acid residues in each chain and the N- and C-terminal ends of the chains are labeled. The coiled-coil regions are indicated by the diagonally striped boxes, while the intra- and interchain disulfide bonds are indicated by solid lines. Carbohydrate attachment sites are labeled with CHO, while thrombin and major plasmin cleavage sites are indicated by T and P, respectively. (Adapted from Fig. 12-1 of Hantgan et al., 2000.)...

There are also some acquired dysfibrinogenemias from alterations to fibrinogen, usually as a result of disease processes. Liver disease (including cirrhosis, hepatitis, or hepatic carcinomas) is the most common cause of these modifications. In these cases, there is usually an increase in the sialic acid content of the fibrinogen s carbohydrate (Martinez et al, 1983). 

Figure 1. Structural and biochemical features of the GPIIb-IIIa fibrinogen receptor. (Solid diamonds) N-linked carbohydrate side changes (Y) tyrosine phosphorylation sites (S-S) disulfide bonds (C) cysteine, (NIK) amino-terminus (COOH) carboxy-terminus (P04) phosphorylation sites. Reprinted with permission from Peerschke BIB and Lopez JA, Platelet Membranes and Receptors, In Thrombosis and Hemorrhage 2, J. Loscalzo and A.L Schafer, eds., Williams and Wilkins, Baltimore, MD, 1998.

Prothrombin is the precursor of the serine protease thrombin, essential for normal haemostasis in activation of platelets and in catalysing the polymerisation of fibrinogen to fibrin. It is synthesized in the liver and contains about 8% total carbohydrate in four N-glycans. Three of these lie on the Pro region and only one is present on the mature a-thrombin molecule. The structure of the thrombin glycan has been determined by mass spectrometry and is the same as that shown in Fig. 5 A with fucose absent or present [77]. 

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