Intrinsic factors storage

A person with pernicious anemia lacks intrinsic factor, a compound required for the absorption of vitamin B12 and its storage in the liver. The diagnosis is confirmed... 

Vitamin B12 (cyanocobalamin) is produced by bacteria B12 generated in the colon, however, is unavailable for absorption (see below). liver, meat, fish, and milk products are rich sources of the vitamin. The minimal requirement is about 1 pg/d. Enteral absorption of vitamin B 2 requires so-called intrinsic factor from parietal cells of the stomach. The complex formed with this glycoprotein undergoes endocytosis in the ileum. Bound to its transport protein, transcobalamin, vitamin B12 is destined for storage in the liver or uptake into tissues. 

Intrinsic factors that may influence potato digestibility include the structure of the starch molecules, the structure of starch granules, the composition of the potato, the presence of phosphate in starch granules, tissue structure, and factors that may affect these, including agronomic and growth history, storage, maturity, and variety. 

There are three classes of vitamin B12 binding proteins intrinsic factor, which facilitates absorption of the vitamin from the ileum R-proteins, which include TC I and TC III (the function of these proteins is not clear, but they probably act as mobile storage forms) and TC II, which is the transport protein responsible for carrying the vitamin to the tissues. Abnormalities of intrinsic factor or TC II could be expected to have serious consequences for the patient, and in recent years a number of such abnormalities have been reported. 

Figure 42-2. Absorption, transport and storage of vitamin Bj. IF = intrinsic factor, a glycoprotein secreted by gastric parietal cells TC = transcobalamins, blood proteins that carry cobalamin to the Uver. (Reproduced, with permission, from D.B. Marks, et al. Basic Medical Biochemistry A Clinical Approach. Philadelphia Lippincott Williams Wilkins, 1996 619.)...

F. 40.7. Absorption, transport, and storage of vitamin B12. Dietary B12 binds to R-binders (haptocorrins) in the stomach and travels to the intestine, where the R-binders are destroyed by pancreatic proteases. The freed B12 then binds to intrinsic factor (IF). B12 is absorbed in the ileum and carried by called transcobalamins (TC) to the hver, where B12 is stored. 

The self-heating of coal is due to a number of complex exothermic reactions. Coal will continue to self-heat provided that there is a continuous air supply and the heat produced is not dissipated. The property of coal to self-heat is determined by many factors, which can be divided into two main types properties of the coal (intrinsic factors) and environment/storage conditions (extrinsic factors). Self-heating results in degradation of the coal by changing its physical and chemical characteristics, factors that can seriously affect boiler performance. 

In the case of food, antioxidants are substances with the ability to delay or prevent the development of rancidity and deterioration of sensory attributes related to flavors and aroma and also function as oxidation inhibitors or retarders. The effectiveness of these additives depends on a number of factors, like intrinsic factors, such as the composition (lipids, carbohydrates and proteins), pH, water activity and oxide reduction potential extrinsic factors, such as temperature, storage time, and humidity and atmospheric conditions processing factors and microbial factors, such as the type and quantity of microorganisms, resilience microorganisms and cellular composition (Davidson and Taylor 2007). 

Fig. 19. Comparison of the intrinsic viscosity and the drag reduction material function (friction factor versus Reynolds number) dependent on storage time, Mw = 8.1 106 g/mol, c = 50 ppm in distilled water, d = 6.1 mm (Wagner)...

Adsorption is sometimes invoked not only as a factor in geochemistry but also as a laboratory nuisance. Analyzed samples are often found to have a superficial or loosely bound component ascribed to air contamination, which is frequently described as adsorbed on the sample. Without further qualification, this makes little sense. An air contamination effect certainly exists, as can be inferred clearly when an intrinsic sample gas is isotopically distinct (cf. Section 2.4), but whether adsorption is responsible or even involved is questionable. In all such noble gas analyses, a necessary step is storage in laboratory vacuum before gas extraction. By definition, adsorbed gas is desorbed under vacuum. The relevant factor is the timescale required... 

The whey produced during cheese and casein manufacturing contains approximately 20% of all milk proteins. It represents a rich and varied mixture of secreted proteins with wide-ranging chemical, physical and functional properties (Smithers et al., 1996). Due to their beneficial functional properties, whey proteins are used as ingredients in many industrial food products (Cheftel and Lorient, 1982). According to Kinsella and Whitehead (1989), functional properties of foods can be explained by the relation of the intrinsic properties of the proteins (amino acid composition and disposition, flexibility, net charge, molecular size, conformation, hydrophobicity, etc.), and various extrinsic factors (method of preparation and storage, temperature, pH, modification process, etc.). 

Weber et al., 1999). Thus, optimum colour stability can be achieved only by using a multifactorial approach, where both intrinsic and extrinsic factors are considered (Bertelsen et aL, 2000). From Fig. 9.7 the effect of the nitrite content on the rate of colour deterioration is evident. Increasing the nitrite content stabilises the colour. This result emphasises the necessity of investigating the specific product of interest in order to define critical levels of packaging and storage factors. 

Delicious taste and aroma are synonyms to fresh and good quality of almost any foodstuff and, undoubtedly, affect the consumer s final opinion and choice. Sensory characteristics of olive oil, a major component in the Mediterranean diet, represent the sum of the sensory parameters that integrate its complex and specific qualitative profile including various intrinsic and extrinsic factors such as cultivar (genetic), weather conditions, stage of ripeness, methods and/or system of harvest and storage (Table 5.13). Regulations and standards related to olive oil sensory evaluation include... 

It is needless to say— and it has also been stressed in the text—that it is not necessary to take the same stringent precautions for all trace metals of interest. The decisive factors determining the significance of contamination errors are, on the one hand, the intrinsic concentration of a metal in a sample and, on the other, the level of that metal in all materials (collection tubes, storage vessels, pipets, reagents, and so forth) with which the sample comes into contact. 

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