Tissue Level

The application of biosolids also increases the nutritional value of blue grama. Tissue levels of nitrogen, phosphorus, potassium, and crude protein increased to recommended tissue concentrations with biosolids treatments. Trace metals in blue grama grass did not increase during the study, thereby eliminating concerns that toxic amounts of these elements could be transferred to grazing animals. 

One of the most popular orally active penicillins in present clinical use is amoxicillin (12). Its oral effectiveness and broad spectrum of activity against common pathogens as well as its better absorption than its closest precedent competitor, ampicillin (14), largely accounts for this. Higher blood and tissue levels of antibiotics is another means of dealing with resistance. In an attempt to achieve yet further improvements in oral bioavailability and hence blood and ti.ssue levels of amoxicillin, the prodmg fumoxicillin (13) is prepared from amoxicillin (12) by treatment with furfural [3]. The imine moiety is less basic than the primary amine so that the isoelectric point of fumoxicillin is more on the acid side than is that of amoxicillin. 

The process whereby cellular and tissue levels of one or more cytochrome P450 enzymes are increased in response to treatment of cells, or a whole organism,... 

Serum endosulfan was 4 pg/L at 30 hours after an agricultural pilot was exposed dermally (and probably also by inhalation) for approximately 45 minutes in clothing that was heavily contaminated with endosulfan and methomyl (Cable and Doherty 1999) the dermal exposure level was not estimated and no other measures of tissue levels of endosulfan were obtained. A study by Kazen et al. (1974) has identified endosulfan residues on the hands of workers after relatively long periods free from exposure. Endosulfan residues were identified on the hands of one worker approximately 30 days after exposure and on the hands of one worker who had not used endosulfan during the preceding season. 

The distribution of endosulfan and endosulfan sulfate was evaluated in the brains of cats given a single intravenous injection of 3 mg/kg endosulfan (Khanna et al. 1979). Peak concentrations of endosulfan in the brain were found at the earliest time point examined (15 minutes after administration) and then decreased. When tissue levels were expressed per gram of tissue, little differential was observed in distribution among the brain areas studied. However, if endosulfan levels were expressed per gram of tissue lipid, higher initial levels were observed in the cerebral cortex and cerebellum than in the spinal cord and brainstem. Loss of endosulfan was most rapid from those areas low in Upid. Endosulfan sulfate levels peaked in the brain at 1 hour postadministration. In contrast, endosulfan sulfate levels in liver peaked within 15 minutes postadministration. The time course of neurotoxic effects observed in the animals in this study corresponded most closely with endosulfan levels in the central nervous system tissues examined. 

The functional form of thyroxine (T3) is generated by the deiodination of T4, and PCBs can influence the tissue levels of this form by disturbing metabolism, as well as by reducing the binding of T4. PCBs have been shown to inhibit the sulfation of thyroid hormones and the deiodination of T4 to T3. They can also induce the glucuronyl transferase that conjugates T4 (Brouwer et al. 1998). 

Koeman, J.H. and van Genderen, H. (1970). Tissue levels in animals and effects caused by chlorinated hydrocarbon insecticides, chlorinated biphenyls, and mercury in the marine environment along the Netherlands coast. FAO Technical Conference on Marine Pollution. Rome, December 1970. 

Study and control groups. Investigators need to consider whether the adverse events that occur are due to abnormalities in the distribution, metabolism, and excretion of drugs as a result of underlying disease. These analyses could be systematically facilitated by having standardized ways of measuring blood (and in some cases, tissue) levels of drugs and their metabolites. 

P-Alanine, a metabolite of cysteine (Figure 34-9), is present in coenzyme A and as P-alanyl dipeptides, principally carnosine (see below). Mammalian tissues form P-alanine from cytosine (Figure 34-9), carnosine, and anserine (Figure 31-2). Mammalian tissues transami-nate P-alanine, forming malonate semialdehyde. Body fluid and tissue levels of P-alanine, taurine, and... 

The Tissue Levels of Copper of Certain Other Metals Are Regulated in Part by Metallothioneins... 

Among 27 prospective and case-control studies, 16 reported inverse associations between some carotenoids and CVDs, taking plasma or serum concentration as carotenoid biomarkers (11 of 16 studies), dietary intake (5 of 16 studies), or adipose tissue level (1 of 16 studies). With regard to the findings from the studies based on CVD risk, only two of seven presented significant inverse associations of carotenoids, particularly lycopene and P-carotene, whereas five studies of nine showed inverse correlations between myocardial infarcts and lycopene and/or P-carotene the others presented no associations. ... 

Both the development and application of bioindicators present a number of methodological considerations. One key requirement is to relate dose/effects studies in the laboratory, and residne levels/efifects studies in the field. For many years, these stndies were condncted by different groups of scientists, and the cotmections were not made (Eisler 1987). Ideally, we should use bioindicators where there are clear links between exposnre levels, tissue levels, and effects (Burger and Gochfeld 2003). The most nseful bioindicators of those we suggest are those where the cotmections have been clearly made. 

Nicholson JK, Osborn D. 1983. Kidney lesions in pelagic seabirds with high tissue levels of cadmium and mercury. J Zool London 200 99-118. 

One compound that has been quite widely used as an aromatic detector molecule in vitro is the naturally occurring amino acid, phenylalanine (Ishimitsu etal., 1984). However, human blood and tissue levels of this amino acid are normally too low for it to scavenge enough of... 

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