Tissue composition

The lipid, water, and protein contents of certain tissues vary markedly as a function of age. For example, the adipose tissues of neonates contain about 55% water and 35% lipids, whereas the corresponding figures for the adult are about 25% and 70%, respectively (Friis-Hansen, 1971). The proportion of water in skin falls as a function of age, due to an increase in collagen. The water contents of liver, brain, and kidneys decrease from birth to adulthood by 5-15%. The decrease in water contents of liver and kidneys is primarily due to an increase in protein, whereas this change in the brain is due to an increase in myelin. The overall composition of muscle in terms of lipid and water does not seem to vary with age (Dickerson Widdowson, 1960). 

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In PBPK models tissue blood perfusion and tissue composition can be characterized independently of the drug thus such a model can be created once and reused for many different drugs. Furthermore, because physical laws (mass conservation, diffusion, or facilitated transport mechanisms) are incor-... 

Bone is a porous tissue composite material containing a fluid phase, a calcified bone mineral, hydroxyapatite (HA), and organic components (mainly, collagen type). The variety of cellular and noncellular components consist of approximately 69% organic and 22% inorganic material and 9% water. The principal constiments of bone tissue are calcium (Ca ), phosphate (PO ), and hydroxyl (OH ) ions and calcium carbonate. There are smaller quantities of sodium, magnesium, and fluoride. The major compound, HA, has the formula Caio(P04)g(OH)2 in its unit cell. The porosity of bone includes membrane-lined capillary blood vessels, which function to transport nutrients and ions in bone, canaliculi, and the lacunae occupied in vivo by bone cells (osteoblasts), and the micropores present in the matrix. 

Although both catechins and proanthocyanidins are currently found in plant tissue composition, as reported above, their isolation requires sometime time-consuming procedures and purity and reproducibility are often suspect. 

The latter issue was addressed more recently by Hamilton et al. who developed a trilayer composite consisting of CPP, articular cartilage (CEP), and NP tissue [125]. By sequential seeding of chondrocytes onto the CPP surface followed 2 weeks later by seeding NP cells onto the matrix produced by the chondrocytes, the authors were able to form a tissue composite construct. Although it appeared that the NP cells were able to maintain a rounded morphology, the interfacial shear load required to... 

Menendez M, Herrera J, Comm FA (2002) Effect of nitrogen and phosphorus supply on growth, chlorophyll content and tissue composition of the macroalga Chaetomorpha linum (O.F. Mlill), Kiitz, in a Mediterranean Coastal Lagoon. Sci Mar 66 355-364... 

Sastry, R S. Lipids of nervous tissue Composition and metabolism. Prog. Lipid Res. 24 69-176,1985. 

Clawson, W.J., A.L. Lesperance, V.R. Bohman, and D.C. Layhee. 1972. Interrelationship of dietary molybdenum and copper on growth and tissue composition of cattle. Jour. Anim. Sci. 34 516-520. 

In order to achieve the firm fixation of the artificial cornea to host tissues, composites of collagen-immobilized poly(vinyl alcohol) hydrogel with hydroxyapatite were synthesized by a hydroxyapatite particles kneading method. The preparation method, characterization, and the results of corneal cell adhesion and proliferation on the composite material were studied. PVA-COL-HAp composites were successfully synthesized. A micro-porous structure of the PVA-COL-HAp could be introduced by hydrochloric acid treatment and the porosity could be controlled by the pH of the hydrochloric acid solution, the treatment time, and the crystallinity of the HAp particles. Chick embryonic keratocyto-like cells were well attached and proliferated on the PVA-COL-HAp composites. This material showed potential for keratoprosthesis application. Further study such as a long-term animal study is now required [241]. 

It is obvious that one should not expect to find in the literature extensive information regarding the composition of the brains, livers, or even muscles of healthy human individualsespecially so since repeated samples would have to be taken for analysis in order to determine conclusively the importance of inter-individual differences. The best that could be hoped for would be extensive "horizontal" studies relative to the composition of blood, secretions, etc., of individual human specimens and, perhaps, more comprehensive data including tissue composition with respect to animals. However, satisfactory studies of this sort have seldom, if ever, been made. More often than not, such horizontal studies as have been made have not been published in complete enough form to give the kind of information needed to answer the questions which we are considering. 

Endothelial permeability Transporter proteins Enzymatic/metabolic activity Disease Tissue composition (drug sequestration) Dose size/volume Conformation Chemical stability Enzymatic stability... 

Several reticulated vitreous carbon (RVC)-plant tissue composite electrodes have also been reported where the open-cell structure of RVC serves as a template for the biocomponent used. One such sensor was constructed by press-fitting 100 pore/in RVC (2-mm thick x 3 or 6 mm OD) cylinders into a 6-mm diameter cavity of a thin-layer cell. The inner side of the disc was pressed into an edge of a copper wire, which provided electrical contact. 

In a first stage, distribution was predicted with tissue composition-based equations and the estimated tissue partition coefficients were combined with clearance estimated by direct scaling of hepatocyte intrinsic clearance in a PBPK model as described earlier. 

Volume of distribution predicted from tissue composition-based equations showed an average fold error of 2.2 and the correlation of predicted versus observed volume for the five compounds was poor. For the prediction of volume of distribution it was assumed that the volume in human (L/kg) was the same as the observed volume in the rat (ranging from 0.9 to 2.8 L/kg for the five compounds). Due to the uncertainty in the prediction of volume, the error range associated with this parameter was set as a uniform distribution over a twofold range. 

Animal cells, surroundings of 431-443 Animal tissue, composition of 31 Ankyrin 405... 

Indraprasit S, Alexander GV, Gonick HC. 1974. Tissue composition of major and trace elements in uremia and hypertension. J Chronic Dis 27 135-161. 

O. Fatibello-Filho, R.R.I. Portugal and L.A. Ramos, A Flexible Potentio-metric Minibiosensor for Urea Based on M11O9- Soybean (Glycine Max L. Merr.) Tissue Composite, 54th Annual Meeting of the International Society of Electrochemistry, Sao Pedro, Brazil, 2003, p. 329. 

A model-based dependence of human tissue-blood partition coefficients of chemicals on lipophilidty and tissue composition was recently described [78], For 36 neutral chemicals, the partitioning between seven different tissues and blood in humans was modeled, considering accumulation in the membrane, protein binding, and dis-... 

Balaz and Lukacova (1999) attempted to model the partitioning of 36 non-ionizable compounds in 7 tissues. Amphiphilic compounds, or those possessing extreme log Kow values, tended to show complex distribution kinetics because of their slow membrane transport. However for the non-amphiphilic, non-ionizable compounds with non-extreme log Kow values studied it should be possible to characterize their distribution characteristics based on tissue blood PCs. Distribution is dependent on membrane accumulation, protein binding, and distribution in the aqueous phase. As these features are global rather than dependent on specific 3D structure, distribution is not expected to be structure-specific. In this study, tissue compositions in terms of their protein, lipid, and water content were taken from published data. This information was used to generate models indicating that partitioning was a non-linear function of the compound s lipophilicity and the specific tissue composition. 

Balaz, S. and Lukacova, V., A model-based dependence of the human tissue/blood partition coefficients of chemicals on lipophilicity and tissue composition, Quant. Struct.-Act. Relat., 18, 361-368, 1999. 

Poulin, P., Krishnan, K. (1996b). A tissue composition-based algorithm for predicting tissue air partition coefficients of organic chemicals. Toxicol. Appl. Pharmacol. 136 126-30. 

There are 32 teeth and over 200 bones in an adult human, each a separate organ with its own essential role. These organs are composed of mineralized tissues, composites of bioorganic, and mineral that record the chemistry of what has been ingested, i.e., the C4 or C3 characteristics of the diet, as well as the overabundance of certain, perhaps hazardous cations, e.g., copper (Pyatt and Grattan, 2001), or shortfall of essential elements, i.e., calcium, that may lead to rickets, usually expressed in the abnormal appearance and function of the long bones. 

As the pregnancy evolves, profound changes occur in physiology, including fluid and tissue composition. 

Lukashi, H. C. (1993). Soft tissue composition and bone minera status Evaluation by dual-energy X-ray absorptiometry. /. Nufr. 123,438-443. 

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