Diffusion: human

Pantothenic acid has also been called vitamin Bf. Excellent sources of the vitamin ore liver. egg.s. and cereals. It is found, however, in the form of CoA. This coenzyme cannot be absorbed directly from the gut. Although no experiments have been conducted in humans, studies on animals indicate that the coenzyme must be hydrolyzed to panthenene and pantothenate. " which arc absorbed by passive diffusion. Human intestinal cells contain enzymes tltat can hydrolyze the coenzyme. Pantothenate is the major form circulating in the blood and is absorbed by individual cells. Once inside ihe cell. CoA is synthesized. 

Affinity chromatography, GFAAS, Kinetic immunoturbidimetry, Radial immuno diffusion. Human serum Foote and Delves (1984)... 

Histamine in the Blood. After its release, histamine diffuses rapidly into the blood stream and surrounding tissues (12). Histamine appears in blood within 2.5 min after its release, peaks at 5 min, and returns to baseline levels by 15 to 30 min. In humans, the diurnal mean of plasma histamine levels is 0.13 ng/g. In urine, elevations of histamine or metaboUtes are more prolonged than plasma elevations. Consequendy, abnormahties are more easily detected by urinary histamine assay. About one-half of the histamine in normal blood is in basophils, one-third in eosinophils, and one-seventh in neutrophils the remainder is distributed among all the other blood components. Increases in blood histamine levels occur in several pathological... 

Toxicity. Many /V-nitrosamines are toxic to animals and cells in culture (4,6—8,88). /V-Nitrosodimethy1amine [62-75-9] (NDMA) is known to be acutely toxic to the Hver in humans, and exposure can result in death (89). Liver damage, diffuse bleeding, edema, and inflammation are toxic effects observed in humans as a result of acute and subacute exposure to NDMA. These effects closely resemble those observed in animals dosed with NDMA (89,90). 

As early as 1967, IFF chemists (11), in an in-depth study of jasmin absolute, identified an ultratrace amount of one of the key compounds in the entire fragrance repoitoire, hydroxycitroneUal [107-75-7] (21). This chemical has been used for many years in almost every "white flower" fragrance to give a very diffusive and lasting lily-of-the-valley and jasmin note, but this represents the only known identification of the compound in nature. This illustrates that the human nose can often predict the presence of a molecule well before the instmmentation becomes sufficiently sensitive to detect it. 

Uranium can enter the human body orally, by inhalation, and through the skin and mucous membranes. Uranium compounds, both soluble and insoluble, ate absorbed most readily from the lungs. In the blood of exposed animals, uranium occurs in two forms in equiUbrium with each other as a nondiffusible complex with plasma proteins and as a diffusible bicarbonate complex (242). 

In humans, vitamin B in phosphorylated forms is mostly unavaHable until hydrolyzed, then passively absorbed in the smaH intestine. The free vitamins are interconverted and suppHed to the ckculation by the Hver, then enter ceHs by simple diffusion and are phosphorylated. A typical adult pool of... 

Erythrocyte Entrapment of Enzymes. Erythrocytes have been used as carriers for therapeutic enzymes in the treatment of inborn errors (249). Exogenous enzymes encapsulated in erythrocytes may be useful both for dehvery of a given enzyme to the site of its intended function and for the degradation of pathologically elevated, diffusible substances in the plasma. In the use of this approach, it is important to determine that the enzyme is completely internalized without adsorption to the erythrocyte membrane. Since exposed protein on the erythrocyte surface may ehcit an immune response following repeated sensitization with enzyme loaded erythrocytes, an immunologic assessment of each potential system in animal models is required prior to human trials (250). 

These three functions involve the movement of O2, CO2, and HjO through the epidermal layers of the leaf. The analogy to human inhalation is obvious. With the diffusion of gases into and out of the leaf, pollutant gases have a direct pathway to the cellular system of the leaf structure. Direct deposition of particulate matter also occurs on the outer surfaces of the leaves. 

Sweating, the other powerful heat loss mechanism actively regulated by the thermoregulatory center, is most developed in humans. With about 2,6 million sweat glands distributed over the skin and neurally controlled, sweat secretion can vary from 0 to 1 I7(h m ). The other, lesser, passive evaporative process of the skin is from the diffusion of water. The primary resistance to this flow is the stratum corneum or outermost 15 pm of the skin. The diffusion resistance of the skin is high in comparison to that of clothing and the boundary layer resistance and as a result makes water loss by diffusion fairly stable at about 500 grams/day. 

The diffusion of waterpower was initially slow— perhaps due to its relatively high capital costs, its geographical inflexibility, and the abundance of manual labor in both the classical Mediterranean world and m China. Only in the declining days of the Roman Empire, for example, did watermills become the standard means of grinding gram m some areas, displacing animal- and human-powered mills. 

The resolution of these columns for protein mixtures, however, was comparably poor. The peak capacity for human serum albumin was near 3 during 20 min gradient elution. Improvement has been reached by covalent binding of PEI (M = 400-600) onto a 330 A silica of 5 pm particle size [38], The peak capacities of ovalbumin and 2a -arid glycoprotein were 30-40 (tgradienl = 20 min). Enhanced peak capacity and resolution probably were due to the more diffuse structure of PEI coupled to silane moieties than that of strictly adsorbed on silica and cross-linked (see Sect, 2.2). Other applications of covalently adsorbed PEI are discussed in Sect. 4.1. 

Walker CM, Levy JA (1989) A diffusible lymphokine produced by CD8+ T lymphocytes suppresses HIV replication. Immunology 66 628-630 Walker RE, Bechtel CM, Natarajan V, Baseler M, Hege KM, Metcalf JA, Stevens R, Hazen A, Blaese RM, Chen CC, Lehman SF, Palensky J, Wittes J, Davey RT, Falloon J, Polls MA, Ko-vacs JA, Broad DF, Levine BL, Roberts MR, Masur H, Lane HC (2000) Long-term in vivo survival of receptor-modified syngeneic T cells in patients with human immunodeficiency virus infection. Blood 96 467 74... 

Mutations in bacteria and mammalian cells (including some that result in human disease) have supported these conclusions. Facilitated diffusion and active transport resemble a substrate-enzyme reaction except that no covalent interaction occurs. These points of resemblance are as follows (1) There is a specific binding site for the solute. (2) The carrier is saturable, so it has a maximum rate of transport (V Figure 41-11). (3) There is a binding constant (Al) ) for the solute, and... 

Hoschele D (2006) Cell culture models for the investigation of NRTI-induced mitochondrial toxicity. Relevance for the prediction of clinical toxicity. Toxicol In Vitro 20(5) 535-546 Itescu S, Brancato LJ et al (1989) A sicca syndrome in HIV infection association with HLA-DR5 and CDS lymphocytosis. Lancet 2(8661) 466 68 Itescu S, Brancato LJ et al (1990) A diffuse infiltrative CDS lymphocytosis syndrome in human immunodeficiency virus (HIV) infection a host immune response associated with HLA-DR5. Ann Intern Med 112(1) 3-10... 

MouUgnier A, Authier FJ et al (1997) Peripheral neuropathy in human immunodefidency virus-infected patients with the diffuse infiltrative lymphocytosis syndrome. Arm Neurol 41(4) 438-445 Moulignier A, Moulonguet A et al (2001) Reversible ALS-like disorder in HIV infection. Neurology 57(6) 995-1001... 

Grant PE, He J, Halpern EF, Wu O, Schaefer PW, Schwamm LH, Budzik RF, Sorensen AG, Koroshetz WJ, Gonzalez RG. Frequency and chnical context of decreased apparent diffusion coefficient reversal in the human brain. Radiology 2001 221 43-50. 

Warach S, Chien D, Li W, Ronthal M, Edelman RR. Fast magnetic resonance diffusion-weighted imaging of acute human stroke. Neurology 1992 42 1717-1723. 

Warach S, Gaa J, Siewert B, Wielopolski P, Edelman RR. Acute human stroke studied by whole brain echo planar diffusion-weighted magnetic resonance imaging. Ann Neurol 1995 37 231-241. 

Schlaug G, Siewert B, Benfield A, Edelman RR, Warach S. Time course of the apparent diffusion coefficient (ADC) abnormality in human stroke. Neurology 1997 49 113-119. 

Fiebach JB, Jansen O, Schellinger PD, Heiland S, Hacke W, Sartor K. Serial analysis of the apparent diffusion coefficient time course in human stroke. Neuroradiology 2002 44 294-298. 

---