Biological behavior liver

To investigate the biological behavior and determine the sites of accumulation of Gd-DTPA-PL-NGPE-liposomes upon intravenous administration, the liposomes were additionally labeled with " In by transchelation from an In-citrate complex and injected into the rabbit with subsequent label distribution monitoring by a y-camera. The radioscintigram taken 2 h post i.v. injection demonstrated characteristic liposome accumulation sites in the liver, spleen, and bone marrow. 

The distribution pattern of intravenously-injected Thorotrast in animals is similar to the pattern in humans most of the Thorotrast is taken up by the RES (Guimaraes et al. 1955 McNeill et al. 1973 Reidel et al. 1979). Reidel et al. (1979) determined that the average percent distribution of Thorotrast in the liver was within one order of magnitude in mice, rats, rabbits, dogs, and humans. The amount of thorium in the spleen of all species, except mice, was clearly below that in humans. Only 50% of the thorium in rats was retained in the liver and spleen, while approximately 85% was retained in humans. Direct comparison of the species is difficult, since the data were taken from other authors and analyzed by Reidel et al. (1979). The study concluded that the biological behavior of colloids was similar in humans and animals. Kaul and Heyder (1972) reported an extremely low rate of clearance of the colloid form from the blood about 1 hour after intravenous injection in rabbits. Subsequently, an increase in the rate of disappearance from the blood of the colloid form (biological half-life of 90 minutes) and of the soluble form (biological half-life of 75 minutes) was found. After 3, 6, or 12 hours, 23, 45, or 60% of the injected amount, respectively, was located in the liver. 

Complexes of the [Tc(N)(/c2-PS)2] type were also synthesized at noncarrier added level and their biological behavior was studied [46]. These compounds exhibited high initial heart uptake, and elimination through liver and kidneys. The washout kinetics from heart was dependent on the nature of the lateral R groups on the phosphine thiol ligands. Extraction of the activity from myo-... 

Limiting organs for high resolution images are the blood pool, kidneys and liver. To optimize the biological behavior of a radiopharmaceutical, the portion essentially represented by the metal complex must be varied. The leading structure, the vector, is in general already optimized but there are also examples where the biomolecule needs to be optimized while the label is kept constant... 

There are of course many mathematically complex ways to perform a risk assessment, but first key questions about the biological data must be resolved. The most sensitive endpoint must be defined along with relevant toxicity and dose-response data. A standard risk assessment approach that is often used is the so-called divide by 10 rule . Dividing the dose by 10 applies a safety factor to ensure that even the most sensitive individuals are protected. Animal studies are typically used to establish a dose-response curve and the most sensitive endpoint. From the dose-response curve a NOAEL dose or no observed adverse effect level is derived. This is the dose at which there appears to be no adverse effects in the animal studies at a particular endpoint, which could be cancer, liver damage, or a neuro-behavioral effect. This dose is then divided by 10 if the animal data are in any way thought to be inadequate. For example, there may be a great deal of variability, or there were adverse effects at the lowest dose, or there were only tests of short-term exposure to the chemical. An additional factor of 10 is used when extrapolating from animals to humans. Last, a factor of 10 is used to account for variability in the human population or to account for sensitive individuals such as children or the elderly. The final number is the reference dose (RfD) or acceptable daily intake (ADI). This process is summarized below. 

The fact that glycogen phosphorylase can be used to polymerize amylose was first demonstrated by Schaffner and Specht [110] in 1938 using yeast phosphorylase. Shortly after, the same behavior was also observed for other phosphorylases from yeast by Kiessling [111, 112], muscles by Cori et al. [113], pea seeds [114] and potatoes by Hanes [115], and preparations from liver by Ostern and Holmes [116], Cori et al. [117] and Ostern et al. [118]. These results opened up the field of enzymatic polymerizations of amylose using glucose-1-phosphate as monomer, and can be considered the first experiments ever to synthesize biological macromolecules in vitro. 

The ability to change the behavior of biological systems to microparticles via surfactant attachment is based on the alteration of the adsorption of proteins to the microparticles. This alteration often involves inhibiting nonspecific adsorptions that normally trigger liver cells to remove the particle from the circulation. 

The antioxidant behavior of astaxanthin has been demonstrated in vivo as well. In Haematococcus algae, astaxanthin is accumulated as part of a stress response, and it is believed to protect cellular DNA from photodynamic damage. This carotenoid also protects lipids from peroxidation in trout and salmon. In chicks, astaxanthin supplementation suppressed the formation of lipid peroxides in the plasma. Significant biological antioxidant effects have been observed in vitamin E-deficient rats fed an astaxanthin-rich diet these include protection of mitochondrial function and inhibition of peroxidation of erythrocyte membranes. In two independent studies, lipid peroxidation in the seram and liver of astaxanthin-fed rats treated with carbon tetrachloride was... 

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