Distribution and accumulation

The absorption, distribution, and accumulation of lead in the human body may be represented by a three-part model (6). The first part consists of red blood cells, which move the lead to the other two parts, soft tissue and bone. The blood cells and soft tissue, represented by the liver and kidney, constitute the mobile part of the lead body burden, which can fluctuate depending on the length of exposure to the pollutant. Lead accumulation over a long period of time occurs in the bones, which store up to 95% of the total body burden. However, the lead in soft tissue represents a potentially greater toxicological hazard and is the more important component of the lead body burden. Lead measured in the urine has been found to be a good index of the amount of mobile lead in the body. The majority of lead is eliminated from the body in the urine and feces, with smaller amounts removed by sweat, hair, and nails. 

Of the various pharmacological actions of PGEj and PGI2, one action which has not yet been studied intensively, but seems to be important for the treatment of arteriosclerotic diseases, is their effect on vascularization. This suggests the need to determine if lipid microspheres accumulate at the site of vascularization. We are now conducting a study to investigate this possibility. Since the space between endothelial cells in new blood vessels is as big as that of vessels with sclerosis or inflammation, lipid microspheres are very likely to accumulate in new blood vessels. Figure 4 shows a schema of the distribution and accumulation of lipid microspheres at the site of vascular lesions. 

After absorption, OC compounds are rapidly distributed and accumulate in high-fat-content tissues the degree of accumulation is inversely related to the rate of biotransformation into water-soluble metabolites. The biological half-lives range from a minimum value of 24 hr for lindane, to 1 year for dieldrin, to 3-4 years for DDT (Tordoir and Van Sittert, 1994). 

Feijtel T.C., Delaune R.D., Patrick Jr. W.H. Biogeochemical control on metal distribution and accumulation in Louisiana sediments. J Environ Qual 1988 17 88-94. 

Distribution, including accumulation of an absorbed substance, will be the same irrespective of the route of administration. However, distribution and accumulation at the site of apphcation (inhalation, oral, dermal) may depend on the route of administration. In such cases, local accumulation may occur and may be responsible for tissue damage. In these cases, systemic toxicokinetics of the substance may be of limited relevance for the risk assessment. It is generally not cmcial for risk assessment to determine the precise tissue distribution profile for a substance. In certain special cases, however, specific tissue distribution studies may assist or even be essential for the interpretation of available toxicological data. For example, it may be of interest to know whether the substance will cross the blood-brain barrier, the placenta barrier, or will accumulate in specific tissues. 

Physico-chemical factors that determine the potential distribution and accumulation of a substance are presented in Table 4.5. 

Physico-Chemical Factors That Determine the Potential Distribution and Accumulation of a Substance... 

The emetines include emetine and dehydroemetine. These drugs act only against trophozoites. Their mechanism of action is based on eukaryote protein synthesis. They are parenterally administered because oral preparations are absorbed erratically and may induce severe vomiting. They are widely distributed and accumulate in liver, lungs and other tissues. The emetines are slowly elimination via the kidneys. Local side-effects in the area of the intramuscular injection are pain, tenderness and muscle weakness. Serious toxicity is common if the drugs are given for more than 10 days. Side effects include nausea, vomiting, diarrhoea but also cardiotoxicity. 

The discussion and studies cited previously generally reflect overall tissue distribution of total arsenic after acute exposure in the case of laboratory animals or unknown exposures in the case of humans. Advances in analytical technology in the last decade have facilitated the identification of tissue-specific patterns of metabolite distribution and accumulation in laboratory animals. Kenyon, Del Razo and Hughes (2005a) found that inorganic arsenic was the predominant form of arsenic in the liver and kidney up to two hours post administration of 10 or 100 p mol As kg-1 as inorganic As(V) to female mice, whereas... 

Kannan, K., Tanabe, S., Tatsukawa, R., 1995. Geographical distribution and accumulation features of organochorine residues in fish in tropical Asia and Oceania. Environ. Sci. Technol. 29, 2673-2683. 

Sudaryanto, A., Kajiwara, N., Takahashi, S., Muawanah, A., Tanabe, S., 2007a. Distribution and accumulation features of PBDEs in human breast milk from Indonesia. Environ. Pollut., in press, doi 10.1016/j.envpol.2007.02.016. 

Buergel PM, Soltero RA. 1983. The distribution and accumulation of aluminum in rainbow trout following a whole-lake alum treatment. J Freshwater Ecol 2 37-44. 

Gordon, E.S., Goni, M.A., Roberts, Q.N., Kineke, G.C., and Allison, M.A. (2001) Organic matter distribution and accumulation on the inner Louisiana shelf west of the Atchafalaya River. Cont. Shelf Res. 21, 1691-1721. 

HARTMANN, T., ZIMMER, M., Organ-specific distribution and accumulation of pyrrolizidine alkaloids during the life history of two annual Senecio species. J. Plant Physiol., 1986,122,67-80. 

Kim SK, Oh JR, ShimWJ, Lee DH, YimUH, Hong SH, ShinYB, Lee DS. 2002. Geographical distribution and accumulation features of organochlorine residues in bivalves from coastal areas of South Korea. Mar Pollut Bull 45 268-279. 

Evaluation of the content of PGMs in airborne particles and dusts is important because of the possibility of their inhalation and accumulation in human lungs. Nanoparticles from autocatalysts can be transported into various parts of the environment (waters, plants, soils, and sediments) and transformed into more bioavailable species. There are data on the higher solubility of platinum from tunnel dusts than from inorganic species emitted from converters [30]. Distribution and accumulation of metals depend on traffic density, distance from the road, and meteorological conditions (wind, rain). The age of an autocatalyst and speed conditions directly affect the amount of nanoparticles released from catalytic... 

As pointed out before, one must strictly distinguish between distribution or accumulation of chemical elements in biomasses and their functions for the corresponding organism the action need not be where the highest concentrations are but elsewhere, even disregarding inactive top concentrations in biogenic mineral phases such as bones or silica fibres fortifying plant shoots. Distribution and accumulation are related to the stability and variety of metal-biomass complexes (e.g. Wiinschmann et al. 2004) whilst function ... 

From all known CRC, carnosine first appeared in muscle maturation. Its transformation into N-acetylcamosine (heart), anserine or ophidine (skeletal muscles) depends on specific en2ymes, thus the amount, to which these compounds are accumulated within the muscle, depends on functional activity of muscle [17]. In brain, besides carnosine, homocamosine is also present, which is synthesized by the same enzyme camosyne synthase having similar affinity to both P-alanine and y-aminobutyric acid. Thus, the ratio between carnosine and its homolog in different regions of brain is defined by the accessibility of substrates for dipeptide synthesis. In whole, tissue specificity in distribution and accumulation of different CRC allows to suggest correlation between the biological features of CRC and functional specificity of different excitable tissues [18]. 

Metformin is rapidly distributed, and accumulates in these tissues in which the drug possesses most of its activity (muscles, intestine, liver). For buformin, diffusion in the peripheral compartment is reported to be faster than the rediffusion, leading to an accumulation in the respective tissues (Lintz et al., 1974). Plasma protein binding of the biguanides is only about 20% (Garret et al., 1972) or even undetectable (Rang and Dale, 1991). 

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