Protein losses

Oliver, C.N., Starke-Reed, P.E., Stadtman, E.R., Liu, G.J., Carney, J.M. and Floyd, R.A. (1990). Oxidative damage to brain proteins, loss of glutamine synthetase activity, and production of free radicals during ischemia/reperfusion-induced injury to gerbil brain. Proc. Natl Acad. Sd. USA 87, 5144-5147. 

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. 

In the context of IHC, the reference material should contain a known amount of the reference protein, and must be treated exactly the same way as the test FFPE tissue sections.11 Furthermore, the effect of fixation/processing on the ability of IHC to detect the reference protein ( loss of antigenicity ), also should be known, to allow for calculation of the original amount present of both reference protein and test analyte. 

Purify the iodinated protein from excess reactants by gel filtration using a desalting resin. The column may be pre-treated by passing a solution of bovine serum albumin (BSA) through it to eliminate nonspecific binding sites that could cause significant protein loss in small-sample applications. 

There have been many reports from several groups that plant culture medium is not conducive to protein stability, and that the retention of secreted proteins in culture media can be very poor [10, 11, 17, 40, 60, 63-66]. The mechanisms responsible for protein loss from plant culture media are not completely understood however, current indications are that multiple factors may be involved. Processes that have been proposed to affect foreign proteins in plant media include protein degradation due to protease activity [10, 17, 20, 38, 60, 65], protein instability due to defined or... 

The heavy metals copper, manganese, cobalt and zinc were omitted individually and in combination from MS and B5 media to determine the effect on antibody stability in solution [63]. When IgG, antibody was added to these modified media in experiments similar to the one represented in Figure 2.2, only the B5 medium without Mn showed a significant improvement in antibody retention relative to normal culture media. Nevertheless, protein losses were considerable as only about 30% of the added antibody could be detected in the Mn-free medium after about 5 h. The beneficial effect of removing Mn was lost when all four heavy metals, Cu, Mn, Co and Zn, were omitted simultaneously. The reason for these results is unclear. Addition of the metal chelating agent ethylenediaminetetraacetate (EDTA) had a negligible effect on antibody retention in both MS and B5 media [63]. 

After peroral intake of nickel sulphate in mice, kidney damage appeared at the corticomedullary junction [296]. There was loss of renal tubular epithelial cells and protein loss, giving numerous hyaline casts in the renal tubules and collecting ducts, especially prominent in the renal papillae. 

The antagonistic properties of FR 900452 have also been examined in a model of endotoxin shock, the haemodynamic and haematological manifestations of this condition closely resembling the changes induced by PAF. FR 900452 (10 mg/kg, i.v.) almost completely prevents PAF (1 /ig/kg, i.v.)-induced thrombocytopenia and leukocytopenia in rabbits [295]. It also significantly inhibits endotoxin (E. coli LPS, 30 /ig/kg, i.v.)-induced thrombocytopenia but not leukocytopenia. The same dose of FR 900452 also causes the decreased arterial blood pressure to return to normal in the endotoxin-induced rat hypotension model, an effect also reported for other PAF inhibitors [121, 274], Finally, FR 900452 has been tested for its therapeutic effect on rat nephrosis induced by aminonucleoside (puromycin, 100 mg/kg, i.p.). At 100 mg/kg twice a day orally for 6 days, the agent significantly reduces urinary protein loss in nephrotic rats [298]. 

A summary of the contributions of various processes to protein intake, protein loss and whole-body protein turnover is presented in Table 8.3. 

Table 8.3 Approximate values for (a) protein intake, (b) protein Loss, (c) protein turnover, each day in a normal adult human...

Nandrolone facilitates formation of body muscle mass and strengthens the process of osseous tissue development. The main indications for using nandrolone, as well as other anabolic steroids, are abnormal protein anabolism, asthenia, diseases accompanied by protein loss, adrenal insufficiency, steroid diabetes, and prolonged condition of sluggishness. Synonyms of this drug used in the form of acid esters are retabolil, fenobolin, eubolin, and many others. 

B CR depressed. C GR depressed. D NEX increased, attributed to endogenous protein loss and not dietary protein loss increased fecal levels of the mucoprotein cenponent glucosamine reported. E Larger animals less likely to die, yet mortality rate did increase. LD(50) 2.26 g/kg- Fatty liver... 

The transition from inactive GDP state to active GTP state may be accelerated by proteins that cause the boimd GDP to dissociate. The guanine nucleotide exchange factors (GEF) play an essential role in signal transduction via Ras proteins. Loss of exchange activity by mutation of the exchange proteins has the same effect in lower organisms as loss of the Ras gene. 

The pRb protein has the characteristics of a tumor suppressor protein. Loss of its function is associated with deregulation of cell division and favors tumor formation (see Chapter 14). 

Individuals with chronic alcoholism are prone to gastritis and have increased susceptibility to blood and plasma protein loss during drinking, which may contribute to anemia and protein malnutrition. Alcohol also reversibly injures the small intestine, leading to diarrhea, weight loss, and multiple vitamin deficiencies. 

Androgens and anabolic steroids have been used in conjunction with dietary measures and exercises in an attempt to reverse protein loss after trauma, surgery, or prolonged immobilization and in patients with debilitating diseases. 

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