Sulfation tissue levels

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). 

The results of the blood tests on Vera Leizd showed that her level of testosterone was normal but that her serum dehydroepiandrosterone sulfate (DHEAS) level was significantly elevated. Which tissue was the most likely source of the androgens that caused Vera s hirsutism (a male pattern of secondary sexual hair growth) ... 

The study of flavanol absorption and metabolism has been carried out for some time, and there are a number of prior reviews on this subject [22-25], Studies on the absorption and metabolism of monomeric flavanols are extensive, going back to the 1950s, though all early work was conducted on pharmacological doses of catechin [26-29]. The metabolic pathways of catechin elucidated in these studies continue to be the models for otiier flavonoids. They indieated that the potential pathways of metabolism are glueuronidation and sulfation as well as methylation, but the plasma and tissue levels of speeifie metaboUtes or their proportions are not refleetive of those present after eonsumption of the same flavanols from foods [30]. 

Since endosulfan is a cytochrome P450-dependent monooxygenase inducer, the quantification of specific enzyme activities (e.g., aminopyrine-A -demethylase, aniline hydroxylase) may indicate that exposure to endosulfan has occurred (Agarwal et al. 1978). Because numerous chemicals and drugs found at hazardous waste sites and elsewhere also induce hepatic enzymes, these measurements are nonspecific and are not necessarily an indicator solely of endosulfan exposure. However, these enzyme levels can be useful indicators of exposure, together with the detection of endosulfan isomers or the sulfate metabolite in the tissues or excreta. 

Exposure Levels in Humans. Endosulfan and endosulfan sulfate can be measured in human blood, urine, and tissues following exposure to high levels in worlq)lace environments or following accidental or intentional ingestion of insechcides containing endosulfan (Coutselinis et al. 1978 Demeter and Heyndrickx 1978 Demeter et al. 1977). However, no monitoring studies are available in which human... 

Within the OAT family, OAT4 is the only transporter expressed at appreciable levels in both the placenta and in the kidney [54]. The membrane localization of OAT4 within these tissues has not been examined. Steroid sulfates, and ochratoxinA are efficient transport substrates of OAT4, whereas PAH is weakly transported [54]. The functional importance of OAT4 in regulating placental permeability and renal drug elimination is currently unknown. 

Through the combined approach of l.c. and the sequential applications of specific glycosaminoglycan-lyases, it is possible to determine the levels of several different glycosaminoglycans in the same tissue-sample. Thus, Gurr and coworkers demonstrated that hyaluronate, chondroitin sulfate... 

After oral administration of radiolabeled tilmicosin to broilers at dosage in tire range 25-450 mg/L in water for 3-5 days, radioactivity was mainly distributed to liver and kidney and, to a lesser extent, to muscle and fat. The parent drug was the main residue in tissues, excreta, and bile, but partly desmethylated, hy-droxylated, reduced, and sulfated metabolites could be also identified. Similar pharmacokinetic characteristics were also observed in cattle, swine, and sheep. In broilers treated with tilmicosin at the recommended dosage, residues of the parent drug in liver were 2.6 ppm at day 3 declining to 0.13 ppm at day 17 residue levels in kidney averaged 0.65 ppm at day 3 and declined via 0.08 ppm on day 10 to below 0.06 ppm thereafter. Residues in muscle, fat, and skin were approximately 0.10 ppm at day 3 and less than 0.014 ppm after day 14. 

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