Protein depletion

Zolotaijova, N., Martosella, J., Nicol, G., Bailey, J., Boyes, B.E., Barrett, W.C. (2005). Differences among techniques for high-abundant protein depletion. Proteomics 5, 3304-3313. 

A single dose oral LDso value of approximately 13,000 mg/kg was reported for mice, and 14 daily doses of 625 mg/kg were lethal for 6 of 20 exposed male mice (Hayes et al. 1986). In rats fed carbon tetrachloride in stock diets or protein-free diets, LDso values of 10,200 or 23,400 mg/kg, respectively were reported (McLean and McLean 1966). The authors attributed the difference in sensitivity in animals in this study to protein depletion which has reportedly afforded protection against carbon tetrachloride toxicity. This may result from protein depletion-induced reduction in cytochrome P-450 synthesis, with a consequent diminished metabolic activation of carbon tetrachloride to toxic metabolites. In other studies using rats, an LDso value of approximately 7,500 mg/kg was reported (Pound et al. 1973), while 17/20 animals were killed within 14 days of a single oral gavage exposure to 8,000 mg/kg (Thakore and Mehendale 1991). Doses as low as 400 mg/kg have resulted in the death of cats (Chandler and Chopra 1926). 

However, studies in hypercholesterolemic subjects, using soy protein depleted of isoflavones have shown that soy protein independently of isoflavones can favorably affect LDL size, LDL particle distribution was shifted to a less atherogenic pattern,and can decrease triglyceride concentrations, triglyceride fatty acid fractional synthesis rate, and cholesterol... 

Kudo, S. 1980C. The heat stability of milk Formation of soluble proteins and protein-depleted micelles at elevated temperatures. N.Z. J. Dairy Sci. Technol. 15, 255-263. 

Laboratory experiments showed that the water content of the muscle of small, immature cod subjected to starvation rose (reflecting protein depletion) from 80% to around 86%, beyond which level the fish died. Larger fish, however, which had spawned several times, could be depleted until the water content of the musculature was over 95% - a remarkable adaptation to the more severe depletion imposed under natural conditions (Love, unpublished). While this phenomenon differs from that described above in fatty fish, it again illustrates a change in the metabolism of fish in response to growth. Likewise, Borisov and Shatunovsky (1973) studied the possibility of using the water content to estimate the natural mortality rate of Barents Sea cod. 

Q3 The thyroid hormones thyroxine and triiodothyronine have many metabolic effects. In adults they increase metabolic rate, oxygen and calorie consumption, stimulate carbohydrate metabolism and turnover of protein, deplete fat stores and increase catabolism of free fatty acids. Thyroid hormones stimulate heart rate and force and increase pulmonary ventilation, gastrointestinal motility and central nervous system (CNS) activity. Actions on the heart can result in an increased incidence of dysrhythmias. Thyroid hormones are critical for the normal growth and development of the infant, particularly in respect of skeletal growth and maturation of the CNS. 

In recent years there have been many attempts to isolate PSII proteinaceous components containing Mn and possibly restoring the Oj evolving ability. It has been reported on proteins [162,163] partially able to restore O2 evolution in protein-depleted vesicles the Mn associated to these preparations was however insufficient to account for the Mn content correlated to O2 evolution in the native membranes. By washing inside-out thylakoids with 250 mM NaCl, Akerlund [164] has extracted a 23 kDa protein free of Mn but reconstituting O2 activity. Several proteinaceous components, not all associated with Mn, could be involved in the oxidizing side of PSII. 

FIGURE 22.3 Schematic description of the process of preparation of the whey protein-depleted skim milk powder. (From Garem, A., Schuck, P., and Maubois, J.-L., Lait, 80, 25, 2000. With permission.)... 

They reported 66%-71% whey proteins depletion and calcium to casein ratio in the MF retentate suitable forLMPS mozzarella cheese with properties comparable to those of commercial products. 

With the objective of increasing calcium and lactose content of MF retentate in addition to micellar casein whUe maximizing whey protein depletion. Nelson and Barbano [114] developed a multistage MF process that removed -95% of whey protein from skim milk. They reported that the MF retentate produced from this process contained soluble minerals, NPN, and lactose similar to the original milk. This was accomplished by using the permeate from the UF of the MF permeate to diafilter the MF retentate after achieving a concentration factor of 3 in the MF. Aside from the recovery of native micellar caseins, they showed that the process enabled the production of whey protein stream (UF retentate) with protein content similar to that of commercial WPC. 

Ogata Y, Charlesworth MC, Muddiman DC (2005) Evaluation of protein depletion methods for the analysis of total-, phospho-and glycoproteins in lumhar cerebrospinal fluid. J Proteome Res 4 837-845. 

Matzno S, Yasuda S, Juman S, Yamamoto Y, Nagareya-Ishida N, Tazuya-Murayama K, Nakabayashi T, Matsuyama K (2005) Statin-induced apoptosis linked with membrane farne-sylated Ras small G protein depletion, rather than geranylated Rho protein. J Pharm Pharmacol 57 1475-1484... 

TFN is a glycoprotein that binds and transports ferric iron to the liver and reticuloendothelial system for storage. As a surrogate marker of nutrition status, it is more likely to decrease in response to protein depletion before serum ALB concentrations decrease because it has a shorter biologic half-life (8 days), and there is less of it in the body (less than 100 mg/kg of body weight). Serum TFN concentrations may be determined by direct measurement or can be estimated indirectly from measurement of total iron-binding capacity (TIBC), where TFN = (TIBC x 0.8) — 43. Critical illness, hydration status, and iron stores affect the serum TFN concentration. In iron deficiency, hepatic TFN synthesis is increased, resulting in increased sermn TFN concentrations unrelated to protein stams. 

Distinction between the effects of injury on protein metabolism and the effects of corticoid on protein metabolism has been made by Munro (M17, MIS) who has found a marked gain in liver nitrogen content following cortisone administration to the rat, but not after femur fracture. He also notes that cortisone has a constant action on nitrogen balance at all levels of protein intake whereas the effect of injury is obliterated by prior protein depletion. 

According to animal studies (Swick and Benevenga, 1977), a labile protein reserve that can be gained or lost from the body for emergencies or to account for the day-to-day variations in dietary protein intake is contained in the liver and visceral tissues. Rapid starvation or dietary protein depletion results in a loss of the reserve by as much as 40%, while skeletal muscle drops much more slowly. Thus, protein breakdovm becomes the source of indispensable amino acids needed for synthesis of critical proteins necessary for body functions (Reeds et ah, 1994) and provides amino acids as precursors for energy production. 

Amino acid solutions (1 to 1.5 g/kg IV daily) will provide nutritional support in patients with renal failure, high metabolic stress, or hepatic encephalopathy with cirrhosis or hepatitis. Amino acid injection and solution provide a substrate for protein synthesis in the protein-depleted patient or enhance conservation of body protein. 

Pure red cell aplasia that responded to the administration of riboflavin was reported in patients with protein depletion and complicating infections. Nutritionists induced riboflavin deficiency in human beings and demonstrated that a hypoproliferative anemia resulted within a month. The spontaneous appearance in human beings of red cell aplasia due to riboflavin deficiency undoubtedly is rare, if it occurs at all. It has been described in combination with infection and protein deficiency, both of which are capable of producing a hypoproliferative anemia. However, it seems reasonable to include riboflavin in the nutritional management of patients with gross, generalized malnutrition. 

Noller and coworkers [98] showed that protein-depleted 23S rRNA had peptidyltransferase activity but it was difficult to eliminate the last traces of protein without losing the transferase activity. Recently, in terms of omission and addition tests using six domains of 23S rRNA synthesized individually by T7 RNA polymerase, Nitta et al. [99, 100] demonstrated conclusively that domain V is inevitably required for peptide bond formation. 

Additional tests were made to help evaluate Mr. Veere s degree of malnutrition and his progress toward recovery. His arm circumference and triceps skinfold were measured, and his mid upper arm muscle circumference was calculated (see Chap. 2, Anthropometric Measurements). His serum transferrin, as well as his serum albumin, were measured. Fasting blood glucose and serum ketone body concentration were determined on blood samples drawn the next day before breakfast. A 24-hour urine specimen was collected to determine ketone body excretion and creatinine excretion for calculation of the creatinine-height index, a measure of protein depletion from skeletal muscle. 

Cholesterol ester transport protein depletes HDL of cholesterol while concomitantly increasing the amount of cholesterol in the outward-going VLDL and LDL particles. At first glance, it may seem disadvantageous for cholesterol to remain in the atherogenic LDL and VLDL fractions of the lipoproteins. However, the mechanism scavenges cholesterol from the periphery, thus relieving cells of the metabolically expensive process of de novo synthesis. 

McDonald, M.L. Swick, R.W. (1981). The effect of protein depletion and repletion on musde-protein turnover in the chick. Biochem. ]., 194, 811—19. 

Separation/characterization of net charge (dissolved proteins depletion method) Capillary electrophoresis (CE)... 

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