Hydrogen specific radioactivity

Steroid chemistry is involved at two points (i) the preparation of a steroid derivative ( hapten e.g. a carboxymethyloxime or a hydrogen succinate ester) suitable for chemical combination with free amino-groups in BSA (see below) and (ii) the synthesis of labelled steroids of high specific radioactivity for use as tracers. 

Labelling with Isotopic Hydrogen.—Various oestrogenic steroids with high specific radioactivity were obtained by reduction of their 2,4-dibromo- or 2,4-iodo-derivatives with tritium gas over 5% Pd-A Oa, to give 2,4-ditritiated products." Betamethasone 17-benzoate (484) was labelled [1,2- H2] by selective reduction of... 

Cyclohexadiene was converted totally on a Ni catalyst when the benzene conversion was - 5-6%. From this point onwards, the concentration of cH dropped dramatically with a simultaneous increase in its specific radioactivity exceeding that of cH, when the Bz conversion reached 10% as shown in Fig. 3. The formation of radioactive cyclohexene from [ C]-benzene supplied further evidence of the existence of stepwise hydrogenation, even if it is not the exclusive route. 

ImmunO lSS iy. Chemiluminescence compounds (eg, acridinium esters and sulfonamides, isoluminol), luciferases (eg, firefly, marine bacterial, Benilla and Varela luciferase), photoproteins (eg, aequorin, Benilld), and components of bioluminescence reactions have been tested as replacements for radioactive labels in both competitive and sandwich-type immunoassays. Acridinium ester labels are used extensively in routine clinical immunoassay analysis designed to detect a wide range of hormones, cancer markers, specific antibodies, specific proteins, and therapeutic dmgs. An acridinium ester label produces a flash of light when it reacts with an alkaline solution of hydrogen peroxide. The detection limit for the label is 0.5 amol. 

The radioactivity of the hydrogen sulfide produced by 28 lemons treated with radioactive elemental sulfur dust, 28 lemons treated with radioactive sulfur dioxide gas, and 28 lemons treated with a radioactive sulfuric acid solution is expressed as per cent specific activity (Table II), which for the purpose of this report is defined as ... 

The specific activity of the sulfur dioxide was 14, 21, and 13% for the elemental sulfur, hydrogen sulfide, and sulfuric acid treated fruit, respectively (Table III). Thus about the same proportion (within experimental error) of sulfur dioxide is derived from the radioactive elemental sulfur and sulfur acids applied in the treatments. 

The alkali-soluble protein of the peel of lemons treated with hydrogen sulfide, sulfur dioxide, and sulfuric acid contained radioactive sulfur, but the fruit treated with hydrogen sulfide had a significantly lower per cent specific activity in the alkali-soluble protein fraction than did the sulfur dioxide or sulfuric acid treated fruits (Table VII). These results suggest that sulfur dioxide and sulfuric acid react with protein more directly, while hydrogen sulfide perhaps must be oxidized first, as indicated in Table III. It also appears (from Table VII) that the alkali-soluble protein may have been dismuted as the amounts isolated were less in both the hydrogen sulfide and sulfur dioxide treated fruit than in the incubated or nonincubated controls. Other evidence of dismutation has been obtained in experiments where incubation at 60° C. was accompanied by the production of free ammonia (18), and the recovery of free ammonia and six amino acids in the exudates of incubated and sulfur-dusted fruits (18). 

Distribution. Cyanide is rapidly distributed by the blood throughout the body. In a study using orally administered radioactively labelled potassium cyanide, radioactivity detected in whole blood or plasma decreased rapidly within 6 hours. Of the low levels of radioactivity detected in the red blood cells, about 94% of the radioactivity recovered was found in the hemolysate of which 70% was detected in the heme fraction, 14-25% in globin, and only 5-10% in cell membranes (Farooqui and Ahmed 1982). Yamamoto et al. (1982) determined that the pattern of distribution of cyanide did not vary with the concentration used. Ballantyne (1983b) observed higher cyanide levels in whole blood than in serum in rabbits exposed dermally to hydrogen cyanide, potassium cyanide, and sodium cyanide. See Section 2.3.2.1 for specific studies on cyanide tissue distribution. 

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