Soft tissue compartment

Durbin and Schmidt (1985) proposed a model for tissue distribution and excretion of absorbed americium in humans. A unique feature of this model is that transfers from plasma to tissues are assumed to be instantaneous therefore, a central plasma (and blood) compartment is not included in the model (see Figure 3-10). Tissue compartments included in the model are slow and fast turnover bone compartments, representing cortical and trabecular bone, respectively liver and slow and fast turnover for other soft tissue compartments. Excretion pathways include urine and feces. Urinary excretion is represented as a sum of the contributions from bone, liver, and other soft tissues. Fecal americium is assumed to be excreted from the liver. 

The Leggett Model simulates lead biokinetics in liver with two compartments the first simulates rapid uptake of lead from plasma and a relatively short removal half-life (days) for transfers to plasma and to the small intestine by biliary secretion a second compartment simulates a more gradual transfer to plasma of approximately 10% of lead uptake in liver. Different transfer rates associated with each compartment are calibrated to reproduce patterns of uptake and retention of lead observed in humans, baboons, and beagles following intravenous injection, as well as blood-to-liver concentration ratios from data on chronically exposed humans. Similarly, the Leggett Model simulates lead biokinetics in three compartments of soft tissues, representing rapid, intermediate, and slow turnover rates (without specific physiologic correlates). 

Calcium is the fifth most common element, and the most prevalent cation, in the body. An average human body contains approximately 1 kg (24.95 mol) of calcium. Calcium is found in three main compartments the skeleton, soft tissues, and extracellular fluid (Table 49-The skeleton contains 99% of the body s calcium, predominantly as extracellular crystals of unknown structure with a composition approaching that of hydroxyapatite [Caio(P04)6(OH)2]. Soft tissues and extracellular fluid contain about 1% of the body s calcium. 

Kinetic studies in man show that the lead body burden consists essentially of three compartments (1) a rapid exchange pool in blood and soft tissues (2) an intermediate exchange pool in muscles, skin and bone marrow (3) a slow exchange pool in dense bones and teeth (biological half-life about 20 years). The amount of lead stored in the latter compartment increases throughout life (Steenhout, 1982 Steenhout and Pourtois, 1981). 

Chelatable lead Years Involves injection and timed collection of urine represents chelatable compartment of lead found mostly in soft tissues partly in bone Biologically Effective Dose Markers... 

Materials synthesis in biology is often conducted in compartments that delimit the extent of growth as well as provide a microenvironment in which parameters such as supersaturation of a precipitating phase can be delicately controlled by active transport of ions. This is how many biomineralization processes take place—for example, the formation of exquisitely patterned mineral plates in the soft tissues of coccolithophores. Mimesis of this principle... 

TBW method). Although body impedance reflects tissue hydration, soft-tissue mass (lean and fat) can also be empirically derived by correlation in healthy subjects because the compartments of soft tissue are correlated with each other through physiological constants. However, physiological constants become flawed in patients with fluid disorders, which accounts for some of the conflicting results in the literature (Kyle et al., 2004). 

An increasing number of examinations are being performed for the evaluation of known or suspected musculoskeletal infection. Multislice CT with 2D and 3D reconstructions are useful tools for detecting infections and abscesses, determining which compartments are involved and for describing the extent of an infection. For this question it is necessary to apply intravenous contrast medium. Multislice CT is also used to evaluate cortical bone and associated soft-tissue masses in suspected osteomyelitis. The presence of sequester can be verified and the response to therapy monitored (Knollmann and COAKLEY 2006). 

Fig. 12.4a-f. Orbital metastasis of prostate cancer affects major wing of sphenoid bone and extraconal compartment of orbit, with bony spiculae extending into the intra-oibital soft tissue mass (arrows). Metastasis causes proptosis of left eyeball (axial MDCT images, a and b), compression of optic nerve in... 

Further causes of airway narrowing are neoplastic lesions. They can exhibit a predilection for the one of the three compartments lumen, wall, or surrounding soft tissue. For the trachea, 90% of the primary tumors in adults are malignant, mainly squamous cell carcinoma (55%) or adenoid cystic carcinoma (18-40%). Only 10% are benign neoplasms such as papiUoma, true mucinous adenoma, hamartoma, fibroma, chondroma, leiomyoma, and granular ceU myoblastoma. In the bronchi non-small cell lung cancer prevails (Marom et al.2001). 

A bone subcompartment accessible to chelants is evident in the adult data of Araki and Ushio (1982), where the extent of plumburesis in human subjects rises with age, an observation consistent with bone Pb increases with age but not the relatively stable soft tissue Pb levels over various age intervals of adulthood. In addition, the likelihood of chelants mobilizing Pb from high stores of Pb can also be seen in the rebound phenomenon using these agents, where an initial significant decline in PbB and increased plumburesis is followed by a rise in PbB owing to re-equilibrating Pb compartments (Chisolm and Barltrop, 1979 Chisolm et al., 1985). 

As it became evident that amputation is not mandatory in patients with soft-tissue sarcoma, and that comparable survival rates can be achieved with adequate tumor resection, limb preservation became a major goal. However, when the tumor is large, expanding into more than one compartment, when it is invading major blood vessels or nerves, or when there is a multifocal appearance, amputation or mutilating surgery are still considered almost inevitable. 

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