Plasma proteins synthesis

Under physiological conditions, values for ncc and PBC vary little. In other words, when plasma protein synthesis is normal and in the absence of any urinary obstruction that would cause urine to back up and increase PBC, the primary factor that affects glomerular filtration is PGC. An increase in PGC leads to an increase in GFR and a decrease in PGC leads to a decrease in GFR. 

Miller LL, Bly CG, Watson ML, Bale WF (1951) The dominant role of the liver in plasma protein synthesis a direct study of the isolated perfused rat liver with the aid of lysine-epsilon-C14. J Exp Med 94(5) 431 53... 

In considering how L-tryptophan can affect various organs, it is appropriate to review how it affects protein synthesis in specific organs. In addition to reports that tryptophan stimulates hepatic and plasma protein synthesis as described in Chapter 4, it has also been reported that tryptophan stimulates protein synthesis in other organs. These studies, other than in liver, are cited in this section. 

Schreiber, G., G. Howlett, M. Nagashima, A. MiUership, H. Martin, J. Urban, and L. Kotler. 1982. The acute phase response of plasma protein synthesis during experimental inflammation. Journal of Biological Chemistry 257 10271-10277... 

The insulin receptor is a transmembrane receptor tyrosine kinase located in the plasma membrane of insulin-sensitive cells (e.g., adipocytes, myocytes, hepatocytes). It mediates the effect of insulin on specific cellular responses (e.g., glucose transport, glycogen synthesis, lipid synthesis, protein synthesis). 

Albumin (69 kDa) is the major protein of human plasma (3.4-4.7 g/dL) and makes up approximately 60% of the total plasma protein. About 40% of albumin is present in the plasma, and the other 60% is present in the extracellular space. The liver produces about 12 g of albumin per day, representing about 25% of total hepatic protein synthesis and half its secreted protein. Albumin is initially synthesized as a preproprotein. Its signal peptide is removed as it passes into the cisternae of the rough endoplasmic reticulum, and a hexapeptide at the resulting amino terminal is subsequently cleaved off farther along the secretory pathway. The synthesis of albumin is depressed in a variety of diseases, particularly those of the liver. The plasma of patients with liver disease often shows a decrease in the ratio of albumin to globulins (decreased albumin-globuhn ratio). The synthesis of albumin decreases rela-... 

Like other cells, a neuron has a nucleus with genetic DNA, although nerve cells cannot divide (replicate) after maturity, and a prominent nucleolus for ribosome synthesis. There are also mitochondria for energy supply as well as a smooth and a rough endoplasmic reticulum for lipid and protein synthesis, and a Golgi apparatus. These are all in a fluid cytosol (cytoplasm), containing enzymes for cell metabolism and NT synthesis and which is surrounded by a phospholipid plasma membrane, impermeable to ions and water-soluble substances. In order to cross the membrane, substances either have to be very lipid soluble or transported by special carrier proteins. It is also the site for NT receptors and the various ion channels important in the control of neuronal excitability. 

While the exact mechanism of action remains unclear, dacarbazine appears to inhibit DNA, RNA, and protein synthesis. Dacarbazine disappears rapidly from the plasma, with a terminal half-life of about 40 minutes. Dacarbazine has shown clinical benefit in the treatment of melanoma, Hodgkin s lymphoma, and soft tissue sarcomas. Side effects include myelosuppression, severe nausea and vomiting, and a flulike syndrome that starts about 7 days after treatment and lasts 1 to 3 weeks. 

The endothelium has many diverse functions that enable it to participate in in-flammatoiy reactions (H27). These include modulation of vascular tone, and hence control of local blood flow changes in structure that allow leakage of fluids and plasma proteins into extravascular tissues local accumulation and subsequent extravasation into tissues of leukocytes and synthesis of surface molecules and soluble factors involved in leukocyte activation (B43). The endothelial cells themselves can modulate vascular tone by the release of vasoactive substances such as prostacyclin, nitric oxide (NO), ET. Endothelium-derived vasoactive substances... 

A decrease in the concentration of plasma proteins causes a decrease in the plasma colloid osmotic pressure. As a result, filtration is increased, reabsorption is decreased, and fluid accumulates in the tissue. Most plasma proteins are made in the liver therefore, a decrease in protein synthesis due to liver failure is an important cause of this condition. Malnutrition may also impair protein synthesis. Finally, kidney disease leading to proteinuria (protein loss in the urine) decreases the concentration of plasma proteins. 

The functions of the calcium-storage capacity of the ER are at least threefold the association of Ca2+ with Ca2+-binding proteins in the ER is part of a chaperone function that is essential for normal protein synthesis the rapid rate of Ca2+ uptake by endoplasmic pumps provides shortterm cytoplasmic Ca2+ buffering that resists untoward and transient changes in [Ca2+] and, finally, many signaling pathways employ elevated [Ca2+] to activate physiological processes. Extensive Ca2+ release from ER is coupled to activation of Ca2+ entry across the plasma membrane, a process known as capacitative calcium entry, which is discussed below. 

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