Sulfate radioactively labeled

In rats, 55-57% of 14C-endrin was metabolized, mostly as the glucuronide of anti-12-hydroxyendrin, in the bile within 24 hours of dosing with 0.5-2.5 mg/kg (Hutson et al. 1975). Other minor components (<10%) were the glucuronides of 3-hydroxy- and 12-ketoendrin. Male rats eliminated 69% of the radioactive label within 3 days and females eliminated 45%. The major metabolite in female rat urine was 12-hydroxy-endrin-O-sulfate. Baldwin et al. (1970) also detected 9-ketoendrin in the urine of rats. 

Sulfate reduction rates in wetlands have been estimated using numerous techniques. These include the measurement of snlfate disappearance in soil cores and the measnrement of snllide concentration. The direct and most sensitive method used to measure sulfate reduction rates is the nse of radioactively labeled sulfate ( S) (Howarth and Merkel, 1994). This method involves injecting into cores and measuring the amonnt of fonnd. The procednre in which is injected into the soil cores has been used by numerous researchers. Measuring sulfate reduction using this procedure is based on the assumption that the H2 S prodnced from the added is retained as free sulfide, and FeS can be liberated and assayed when the soil is acidified. Measurement of the incorporation of into acid-volatile samples may underestimate snlfate reduction rates because some of the enters sulfur pools that are not acid volatile. It has been shown that an appreciable portion of the reduced is also incorporated into non-acid snlfnr componnds snch as pyrite and elemental sulfur. 

A 25.0-mL sample of 0.050 M bariinn nitrate solution was mixed with 25.0 mL of 0.050 M sodiinn sulfate solution labeled with radioactive sulfur-35. The activity of the initial sodium sulfate solution was 1.22 X 10 Bq/mL. After the resultant precipitate was removed by filtration, the remaining filtrate was found to have an activity of 250 Bq/mL. (a) Write a balanced chemical equation for the reaction that occurred, (b) Calculate the K p for the precipitate under the conditions of the experiment. 

Sulfate reduction S-sulfate reduction Radioactively labeled sulfate is incubated in field sample. H S formed is liberated by acid addition, trapped on a zinc acetate wick, and measured by scintillation counter. A specialized lab technique useful in discovering nutrient sources for MIC and in quickly screening biocide activity in samples taken from the target system. 

Whole Cell The conversion of a radioisotopically labeled substrate can be used to assess the potential activity of microbial populations in field samples. The technique depends on bacterial growth for detection, but it generates results in about two days and is specific to SRBs. The sample is incubated with a known trace amount of radioactive-labeled sulfate. (SRBs reduce sulfate to sulfide.) After incubation, the reaction is terminated by adding an acid to kill the cells and the radioactive sulfide is fixed with zinc acetate for evaluation. This is a highly specialized technique, involving expensive laboratory equipment and the handling of radioactive substances [19]. 

The thiazolecarboxylic acid structure (40) was also guessed in a similar way, from tracer experiments. The unknown compound was converted into the thiamine thiazole by heating at 100°C and pH 2. On paper electrophoresis, it migrated as an anion at pH 4. Tracer experiments indicated that it incorporated C-l and C-2 of L-tyrosine, and the sulfur of sulfate. The synthetic acid was prepared by carboxylation of the lithium derivative of the thiamine thiazole, and the derivatives shown in Scheme 19 were obtained by conventional methods. Again, the radioactivity of the unknown, labeled with 35S could not be separated from structure 40, added as carrier, and the molar radioactivity remained constant through several recrystallizations and the derivatizations of Scheme 17. 

Aniline is rapidly and extensively metabolized following oral administration. In the pig and sheep, approximately 30% of a 50-mg/kg dose of 14C-labeled aniline was excreted in the urine, as measured by 14C activity, within 3 h after administration, whereas approximately 50% of the dose was excreted in rats. Within 24 h, more than half the administered dose was excreted by pigs and sheep and 96% of the dose was excreted by rats. Fecal radioactivity was low. A-acetylated metabolites accounted for most of the excretion—/V-acetyl-/>-aminophenyl glucuronide being the primary metabolite in sheep and pig urine and /V-acetyl-/>-aminophenyl sulfate being the primary metabolite in the rat (Kao et al. 1978). Biologic monitoring of workers exposed to aniline showed that /i-aminophenol constituted 15-55% of the parent compound in the urine the o- and ra-isomers were also formed (Piotrowski 1984). 

In rabbits administered radio-labeled endrin, 50% of the radioactivity was excreted in the urine over a 50-day period (Bedford et al. 1975b). Excretion of the label was 87% complete within 13 days. The major compounds detected in urine were anti-12-hydroxyendrin sulfate and 3-hydroxyendrin sulfate (14%). 

Specific Antibody Determination. Serum samples were prepared from each bleed by centrifugation to remove clotted material. 100 ul of the sera was incubated for 30 minutes with sufficient H-STXOL to provide a ca. 20 fold excess of hapten to the anticipated quantity of specific binding sites. The radioactivity of the protein pellet was determined after ammonium sulfate precipitation. After correction for a small amount of non-specific adsorption of label by control sera proteins the mg/ml of specific antibody in the sample was calculated. 

The combination of radiolabeled sulfide and the bimane-HPLC method is particularly powerful because one of the main obstacles to the use of labeled sulfide is, that aside from radioactive decay, the compound is subject to rapid oxidation in the presence of air. The breakdown products of chemical sulfide oxidation are the same as those of biological oxidation. Previously it has been impossible to check routinely the purity of the purchased isotope and its subsequent purity during a series of experiments. It is our experience that newly purchased sodium sulfide sometimes contains up to 10% thiosulfate as well as traces of sulfite and sulfate (Figure 2), and that the sulfide once hydrated readily oxidizes if stored in a normal refrigerator. 

Working with a mutated bacterial strain, Isbister et al. (62) demonstrated a novel mechanism of aerobic oxidation of dibenzothiophene which involved the specific excision of the sulfur atom from the molecule (Figure 11). Studies with -labeled dibenzothiophene showed the release of the radioactivity into the aqueous phase and ion chromatography showed the appearence of sulfate. There was no radioactive carbon dioxide released when this microorganism was incubated with 14C-labeled dibenzothiophene. GC-MS analysis showed that the oxidation product was 2,2 -dihydroxybiphenyl. Kargi and Robinson (52) also report the release of sulfate from dibenzothiophene. This OSC served as the sole carbon and sulfur source in their cultures of the aerobic thermophile Sulfolobus acidocaldarius. 

Crocker sarcoma and Mecca lymphosarcoma tumors were found to accumulate the radioselenium slowly and continuously in contrast to rapid uptake and clearance of the label from most normal organs. Clinically, the affinity of tumors for selenium has been the basis for utilizing a radioactive nuclide of selenium as a tumor localizing agent (62, 64) The reason for the localization of selenium is not readily apparent but may reflect enhanced division rates, protein and chondroitin sulfate biosynthesis, or a decrease in the detoxification of selenium. An outgrowth of these observations has been to examine the in vitro effects of selenium supplementation on cellular propagation. 

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