Total Recovery Of Radioactivity Research Articles

Pharmacokinetics of intravenously administered bumetanide in man

Disposition of [14C]bumetanide administered intravenously to four healthy volunteers could be described by a triexponential equation. The mean half-lives associated with each exponent were 5.9 min, 46 min, and 3.1 hr, respectively. The largest fraction of dose was eliminated during the second phase; only 17% was eliminated during the last phase. The total plasma clearance averaged 228 ml/min, with renal clearance about one-half of this value. The recovery of unchanged bumetanide in urine over 2 days was 47% of the dose, while the total recovery of radioactivity in urine averaged 82% of dose. In plasma 93% of bumetanide was bound to proteins. Thus bumetanide is rapidly eliminated by both renal and nonrenal mechanisms. The elimination kinetics resembled those described for furosemide.

Uptake, distribution and persistence of14C-labelled N-dimethylaminosuccinamic acid in fruiting apple trees

The leaves of three-year-old apple trees, cv Cox’s Orange Pippin, were painted with 14C labelled daminozide in June. At intervals from 24 after treatment until December whole trees were sampled to measure the recovery of total radioactivity and its distribution between the various tissues. The proportion of radioactivity present as unchanged daminozide was also determined.There was no consistent change with time in the total amount of radioactivity found in each tree and the overall mean recovery was 23%. Daminozide moved rapidly throughout the plant and was found in all tissues except the roots within 48 h. Over half the radioactivity that migrated from the treated leaves was eventually accumulated by the fruits. Breakdown of daminozide in the trees was slow; for two weeks after treatment 70-80% of the radioactivity in each tissue was unchanged growth retardant. This value decreased steadily with time in all tissues except the fruit, in which a constant high percentage of daminozide was found at all times. Of the 80 mg daminozide applied to the leaves c. 20 mg was absorbed. Almost half of this was metabolized but about 7 mg persisted in the harvested fruit, 2 mg was in the fallen leaves and a similar amount remained in the tree framework. The significance of these results is discussed in relation to previous reports of the movement and metabolism of daminozide.

The [formula omitted][formula omitted] metabolism of 7β,17-dimethyltestosterone-6,7- 3H

7β,17-Dimethyltestosterone (17β-hydroxy-7β,17-dimethyl-4-androsten-3-one) (I) was given to three subjects in oral doses of 400 mg per day for ten days. The initial dose contained the steroid tritiated in the 6 and 7 positions. Plasma levels and urinary excretion patterns were followed in all three subjects., Isolations were done on the urine, plasma and stools of one patient. From the urine 7β,17-dimethyl- 5α-androstane-3β,17β-diol (VI) was isolated from the nonhydrolyzed fractions., Unchanged (I), 7β,17-dimethyl-5β-androstane-3α, 17β-diol (III) and 7β,17-dimethyl-5β-androstane-3β,17β-diol (IV) were isolated from the nonhydrolyzed and enzyme-hydrolyzed fractions. 7β,17-Dimethyl-5α-androstane-3α,17β-diol (V) was isolated from the enzymatic fractions. From the stools were isolated unchanged (I), (III), (IV), (V) and (VI). Unchanged (I) and its 5α-dihydro derivative (17β-hydroxy-7β,17-dimethyl-5α-androstan-3-one) (II) were identified in the plasma, The total recovery of radioactivity in the one patient on whom the isolations were done was 57%; 40% from the urine and 17% from the stools

Turnover of Lipoproteins and Transfer to Milk Fat of Dietary (1-Carbon-14) Linoleic Acid in Lactating Cows

Chylomicra and very low density lipoproteins labeled with 1-Carbon-14 linoleic acid were isolated from thoracic duct lymph of a calf fed the labeled fatty acid and injected into lactating cows fed a control diet of hay, grain, and corn silage (Experiments 1 and 3) or a high grain-restricted roughage diet (Experiment 2). Fractional removal rates (min−1) of lipoprotein fractions were .429, .538, and .280 for very low density lipoproteins (density less than 1.02 g/ml) and .0116, .00186, and .00610 for low density lipoproteins (density 1.04–1.08 g/ml). Particle size of injected material influenced rate of removal of very low density lipoproteins whereas removal of low density lipoproteins was slowest in the cow fed a high grain diet.In two additional experiments, labeled linoleic acid was placed postruminally through a rumen fistula. Total recovery of radioactivity and curve analysis of radioactivity disappearance in the milk fat of all five trials were used to model lipoprotein metabolism. The model suggests that 76% of absorbed lipid is taken up directly by the mammary gland and that 44% of milk fat is of direct dietary origin.

The secretion rates of deoxycorticosterone and corticosterone in young and elderly men.

After intravenous administration of 14C-deoxycorticosterone (DOC) and 3H-corticosterone (B) to 6 young and 7 elderly men, there was no significant difference between the two groups for the total recovery of radioactivity in the urine and neutral extract at the end of 2 days, although the elderly men excreted radioactivity at a significantly slower rate within that time period than young men. Excluding the atypical values for secretion rates (SRs) of DOC and B and for excretion of 17-hydroxycorticosteroids (17-OHCS) for one subject in each age group, the mean SRs for DOC were 0.089 mg/day and 0.047 mg/day, and for B, 3.3 mg/day and 2.0 mg/day, for young and elderly men, respectively. Mean excretion of 17-OHCS for young men was 5.9 mg/day and 4.0 mg/day for elderly subjects. All 3 measures were significantly less for elderly men. For the total sample of 13 men, SRs of DOC correlated significantly with SRs for B and with excretion of 17-OHCS, as did SRs of B with 17-OHCS.

Effects of ingredients on the oxidation of linoleic acid by lipoxygenase in bread doughs

AbstractFlour and water doughs containing 1‐14C‐linoleic acid (18:2) and various ingredients were prepared to study the oxidation of linoleic acid by lipoxygenase in bread doughs. Lipids were extracted, treated with diazomethane, and 14C‐labelled fatty acid methyl esters separated by thin‐layer chromatography. Radioactivity was determined in silica gel bands containing unoxidised 18:2, hydroperoxy acids (L1), hydroxy acids (L2), hydroxyepoxy acids (L3) and trihydroxy acids (L4). Minor components detected by autoradiography were present mainly in L3 and L4. Recoveries of total radioactivity were always > 95%. Untreated flour‐water dough was mixed aerobically for ˜4 min, rested, and the lipids extracted after 10 min total dough time. Yields of 14C products were unoxidised 18:2 = 28.6 μmol, L4 = 93.9 μmol/100 g dry flour. Similar yields were obtained from ClO2‐treated flour, both after 10 min and 60 min dough time. Salt, salt + yeast, or salt + yeast + ascorbic acid in the dough did not reduce 18:2 oxidation significantly, but increased L3 at the expense of L4. Soya flour preparations inhibited linoleic acid oxidation by 25–44%, but pure soya lipoxygenase had no effect at all. Heat treatment reduced the inhibitory effect of soya flour. Accessible thiol groups were not essential for lipoxygenase activity or for the reduction of L1 to L2 since adding cysteine or N‐ethyl maleimide had negligible effects on the 18:2 oxidation products. Most of the flour carotenoids (xanthophylls) were bleached by wheat enzymes in non supplemented doughs, and all were bleached in doughs supplemented with soya flour. 14C‐labelled triglyceride was not oxidised except in doughs containing soya flour mixed in air (1.5% oxidation) or oxygen (3 % oxidation). Soya flour contains lipoxygenase isoenzymes (principally lipoxygenase‐2) which oxidise linoleate in triglycerides. This isoenzyme is evidently not present in wheat.

Binding-site interaction of chlorthalidone and acetazolamide, two drugs transported by red blood cells.

When 14C-chlorthalidone was administered orally to 2 healthy volunteers, the total recovery of radioactivity in urine (about 75 percent) and feces was close to 100 percent. Most of the label recovered in the blood was bound to the blood cells. When the procedure was repeated while the 2 subjects were receiving acetazolamide, the excretion of labeled material in urine and feces was essentially unchanged, but the blood cells contained less and the plasma more of the blood radioactivity. The half-life of the radioactivity in plasma and blood cells had decreased by about 65 percent. Intravenous administration of acetazolamide (single dose) to 2 other subjects who had received 14C-chlorthalidone orally resulted in a marked drop in the blood cell radioactivity, whereas that in plasma increased. The affinity of chlorthalidone for red blood cells was further evidenced on incubation of 14C-chlorthalidone with human blood. Of the incubated radioactivity, 94 percent to 99 percent was recovered in the erythrocytes. Preincubation of the blood samples with acetazolamide prior to the addition of 14C-chlorthalidone, as well as incubation of acetozolamide in blood samples previously incubated with 14C-chlorthalidone, demonstrated that acetazolamide is able to inhibit and to displace chlorthalidone from blood cells. There are several lines of evidence indicating that chlorthalidone is transported attached to the erythrocyte carbonic anhydrase.

Metabolism of prostaglandin F 2α, in rhesus monkeys

[9- 3H] Prostaglandin F 2α: Tris salt was given intravenously to three female Rhesus monkeys at a dose level of 3.22 mg per monkey (equivalent to 2.4 mg of free acid). Plasma and sequential urine and feces specimens were collected and analyzed for radioactivity. During the seven-day collection period, an average (± S.D.) of 83.39 ± 1.36% of the dose was recovered in the urine, 10.08 ± 1.33% in the feces. The total recovery of radioactivity was 95.04 ± 0.68%. Tritiated water accounted for 1.75 ± 0.80% of the dose. The metabolic transformation of tritium labeled prostaglandin F 2α was investigated in Rhesus monkeys following chronic intravenous infusion. The profile of prostaglandin F 2α metabolites found in monkeys was similar to that found in humans. The following metabolites of prostaglandin F 2α were isolated and identified from the urine of the intravenously-dosed monkeys: 7,9-dihydroxyhexanorprost-3-en-1, 14-dioic acid (III), 7,9-dihydroxy-13-ketodinorprost-3-enoic acid (IV), 7,9,18-trihydroxy-13-ketodinorprost-3-enoic acid (V), 7,9-dihydroxy-13-ketodinorprost-3-en-1, 18-dioic acid (VI), 7,9-dihydroxy-13-ketotetranorprost-3-en-1, 16-dioic acid (VII), 5,7-dihydroxy-11-ketotetranorprostanoic acid (VIII), 5,7,16-trihydroxy-11-ketotetranorprostanoic acid (IX), 5,7-dihydroxy-11-ketotetranorprost-1, 16-dioic acid (X), 5,7-dihydroxy-11-ketotetranorprost-1, 14-dioic acid (XI), 5,7,15-trihydroxy-11-ketotetranorprostanoic acid (XII), 7,9,13-trihydroxydinorprost-3-enoic acid (XIII), 5,7,11-trihydroxytetranorprostanoic acid (XIV), 7,9,13-trihydroxytetranorprost-3-en-1,16-dioic acid (XV) and 5,7,11-trihydroxytetranorprost-1,16-dioic acid (XVI). Compounds VIII, IX, X, XI, XIV and XVI were also found as their corresponding δ-lactone derivatives. Compound XV was present only in the form of γ-lactone.

Metabolism of prostaglandin F 2α in the rat

Tritium-labeled prostaglandin F 2α (Tris salt) was given intravenously to female rats at a dose level of 1.2 mg/kg body wt. Sequential urine and feces specimens were collected and analyzed for radioactivity. It was found that average recovery of total radioactivity was 92.7% with 65.1% in the urine and 15.3% in the feces. The amount of tritiated water produced metabolically was estimated to be 12.32% of the dose. The metabolic transformation of tritium-labeled prostaglandin F 2α was investigated in rats following chronic intravenous infusion. The following six urinary metabolites were isolated and identified: 5,7-dihydroxy-II-ketotetranorprostanoic acid; 5,7,15-trihydroxy-II-ketotetranorprostanoic acid; 5,7,16-trihydroxy-II-ketotetranorprostanoic acid; 5,7-dihydroxy-II-ketotetranorprosta-1,16-dioic acid; 5,7-dihydroxy-II-ketotetranor-(ω-dinor)-prosta-1,14-dioic acid and 5,7,11-trihydroxy-tetranorprosta-1,16-dioic acid. The six metabolites were also present as the corresponding δ-lactones. The major metabolite was 5,7-dihydroxy-11-keto-tetranorprosta-1, 16-dioic acid which accounted for slightly less than half of the radioactivity extracted from the urine.

MEASUREMENTS OF 125I LABELLED METABOLITES IN HUMAN THYROID TISSUE

ABSTRACT The results of paper-chromatographic separation and measurements of radioactive-labelled, iodinated metabolites in digested thyroid tissue depend to a great extent on the procedure chosen. The purpose of the present study was to develop a valid and reproducible procedure for human thyroid specimens. We have systematically evaluated the following steps in the procedure: 1) removal of representative tissue for mean distribution of 125I and [125I] aminoacids, 2) chromatography of undigested thyroid homogenate, 3) propylthiouracil (PTU) versus 1-methyl-2-mercaptoimidazole (MMI) in the digest buffer, 4) digestion time using Pronase, 5) digestion of »whole« versus centrifuged homogenate, 6) chromatography of »whole«-digest versus supernatant of centrifuged digest, 7) chromatography in acid and alkaline solvents. Based on this investigation the following standard procedure was chosen: Representative tissue specimens were homogenized in Tris-acetic acid buffer 0.2 m, pH 8.6 containing PTU 7 × 10−4 m, tissue concentration 40 mg/ml. »Whole«-homogenate was digested at 37°C for 24 hours with added Pronase 4 mg/ml + toluol. »Whole«-digest was applied to Whatmann 3 MM paper for approximately 10 hours of ascending chromatography. The solvent used was n-butanol-ethanol-ammonia 0.4 n (15:3:6). The standard procedure was checked by 65 duplicate estimations and found to be highly reproducible. Extensive recovery experiments with in vitro added [125I] aminoacids and Na125I revealed a total radioactivity recovery of 96% for DIT, 93% for MIT, 95% for I−, 98% for T4 and 90% for T3. The relative recovery, an expression of the stability of individual compound, was about 100% for MIT, DIT and I−, but only 75% for T4 and 77% for T3.

Membrane receptors and platelet function IV. Interaction of platelet populations with 125I-Fibrinogen

In vitro and in vivo interaction of human blood platelet populations of various densities (ages) with 125I-Fibrinogen ( 125I-Fg) have been studied. The four platelet populations have been isolated by ultracentrifugation of the circulating platelets on a discontinuous sucrose density gradient. In vitro exposure of platelets to human 125I-Fg before or after the separation of platelet populations results in 67.8% and 62.6% recovery of total radioactivity in the light platelets (A and B populations). When 125I-Fg was injected in normal human, 2 hours after injection, 70.3% of the total radioactivity bound to platelets was recovered in the same A and B platelet populations. The close similarity of platelet population behaviour in vitro and in vivo towards the labelled fibrinogen suggest a selective ability of these platelets to bind or to incorporate the fibrinogen.

Effects of dibutyryl cyclic adenosine 3', 5'-monophosphate on pyruvate metabolism in rat adipose tissue

The effects of the dibutyryl derivative of adenosine 3',5'-monophosphate (cyclic AMP) on pyruvate metabolism in segments of rat epididymal adipose tissue were evaluated. The oxidation of [1- 14C]pyruvate and [1- 14C]lactate to 14CO 2 was accelerated by dibutyryl cyclic AMP at a concentration too low to activate lipolysis (0.30 mM). Higher, lipolytic concentrations further augmented oxidation of [1- 14C]pyruvate. Oxidation of [3- 14C]pyruvate was progressively increased by dibutyryl cyclic AMP while conversion to fatty acid was depressed. Total recovery of radioactivity from [3- 14C]pyruvate in CO 2 and triglyceride was increased by dibutyryl cyclic AMP. Cyclic AMP (10 −5–10 −3 M) increased the activity of pyruvate dehydrogenase in homogenates of adipose tissue. These data suggest that dibutyryl cyclic AMP increases the entry of pyruvate into the citric acid cycle, perhaps by activating pyruvate dehydrogenase. The data further suggest that dibutyryl cyclic AMP must exert some other direct or indirect action later in the metabolic scheme to curtail lipogenesis.

Effects of dibutyryl cyclic adenosine 3′,5′-monophosphate on glucose transport and metabolism in rat adipose tissue

The effects of the dibutyryl derivative of cyclic AMP ( N 6-2′- O-dibutyryl cyclic adenosine-3′,5′-monophosphate, DBC) on glucose metabolism in segments of rat epididymal adipose tissue and isolated fat cells were evaluated. The oxidation of glucose to CO 2 and its conversion to triglyceride was accelerated by DBC at a concentration too low to activate lipolysis (0.30 mM). Higher, lipolytic concentrations further increased oxidation of glucose but depressed lipogenesis. Oxidation of glucose carbon-6(C-6) was progressively increased by DBC while the oxidation of carbon-1 (C-1) was unaffected. Incorporation of C-6 into fatty acid was depressed by DBC but incorporation of C-1 was unchanged. Glyceride-glycerol formation from both C-1 and C-6 was stimulated by cyclic nucleotide. Total recovery of radioactivity from C-1 and C-6 in C0 2 and triglyceride was increased by DBC. DBC also increased the uptake of the non-utilizable sugar d-xylose by adipose tissue. At 0.30 mM, DBC also increased glucose metabolism in isolated fat cells, but higher concentrations progressively inhibited glucose metabolism. These data indicate that DBC stimulated the oxidation of glucose by segments of rat epididymal adipose tissue and suggest that this stimulation may be ascribed, at least in part, to accelerated entry of sugar into the adipose cells. The data also are consistent with the view that cyclic AMP may enhance the Embden-Meyerhof pathway of glucose metabolism at the expense of the pentose cycle, that it inhibits lipogenesis, and it may mediate all the actions of epinephrine on glucose oxidation in adipose tissue.

Metabolism of subcutaneously injected 14C-histamine in myxine glutinosa.

AbstractThe recovery of total radioactivity, 14C‐histamine and 14C‐methylhistamine in extracts of whole Myxine glutinosa was determined after s.c. injection of 14C‐histamine. 24 hrs after injection the same parameters were determined in single organs. Total radioactivity declined very slowly, 10 days after administration 71% was recovered. At that time 14C‐histamine and 14C‐methylhistamine amounted to 44% and 1% respectively of the given dose. The liver was the most efficient organ in extracting radioactivity.

Metabolism of Hempa Uniformly Labeled with C14 in Male House Flies13

When hempa was uniformly labeled with C14 and its metabolism in male house flies, Musca domestica L., was studied, total recovery of radioactivity from treated flies and their excreta was about 90%. The recovery of radioactivity from respiratory CO2 was only 1.25% of the injected 5.71 μg of C14-hempa/fly during the first 24 hours. Radiometric and colorimetric determinations indicated that 2.5-3 hours after treatment, treated flies retained 50% of the dose and that at the end of 24 hours they retained about 2-3% of the dose. The treated flies were 50% sterile 4 hours 45 minutes after treatment and completely sterile about 7 hours after treatment. The only major metabolite of hempa found in treated flies and in their excreta was pentamethylphosphoric triamide. Unchanged hempa and its metabolite were separated from the extracts of treated flies and their excreta by thin-layer chromatography, gas-liquid chromatography, and radiochromatography. For identification, the 2 compounds were isolated by thin-layer chromatography, and their structure was confirmed by infrared spectroscopy.

Disposition of dehydroepiandrosterone and its sulfate in human subjects.

ABSTRACT The disposition of 4-14C dehydroepiandrosterone (D) and 7α-3H dehydroepiandrosterone sulfate (DS) (3H/14C =5.0) was studied in 11 subjects, 5 of whom had biliary fistulas. The mixture of D and DS was injected intravenously in 9 subjects and taken orally by 2 subjects. About 2% of 14C appeared in the bile, whereas 11% of 3H was excreted by that route. Urinary excretion in intact subjects was 45% of the 14C and 55% of the 3H. The total recovery of radioactivity was the same in all groups, indicating intestinal absorption of D and DS. This conclusion was confirmed by the results of oral ingestion, which closely resembled those following intravenous administration. The 3H/14C ratio of urinary testosterone glucosiduronide was initially 1/10 of that injected, suggesting that of the 2 steroids administered DS is a poorer precursor of testosterone.

Metabolism of 131-I- and 14-C-labeled thyroxines.

Thyroxine metabolism was studied with 4 radiothyroxines labeled as follows: 1) with 131I at 3', 5' positions, 2) with 14C in the beta carbon of the alanine side chain, 3) with 14C in the alanine side chain and ring A, and 4) with 14C in ring B. The study was made in thyroidectomized rats, maintained in a euthyroid state by a daily injection of thyroxine (T4), 15 μg/kg. At the start of an experiment, the replacement therapy was substituted with the injection of a radiothyroxine. Their biological t1, urinary and fecal excretion, and the metabolites in blood, bile, urine and feces of these radiothyroxies were compared. The latter 2 radiothyroxines had t1s of 28.9 and 20.8 hr, while the first 2 radiothyroxines showed similar t1s of 16.6 hr. The total recovery of radioactivity over 10 days was 70- 90% in all experiments, approximately ⅓ of which was recovered in the feces. The urinary recovery varied between groups: more l3lI than 14C was recovered and the least 14C was recovered from the ring B-labeled T4. In...

Fate of Tepa Uniformly Labeled with C14 in Male House Flies23

Tepa uniformly labeled with C14 with a specific activity of 12 mc/mmole was used to study the metabolism and mechanism of sterilization in male house flies, Musca fomestica L. A wet-combustinon method was developed for C14-labeled compounds which gave quantitative recovery and reproducible results. The injection of C14-labeled tepa was adjusted to about 1 µg per male fly. Total recovery of radioactivity from treated flies and their excreta was almost quantitative; radioactivity in respiratory CO2 was only 0.75% of the injected dose during the first 12 hours. When male flies were allowed normal activities after an injection of about 1 µg of C14-labeled tepa, 50% of the dose was retained in the fly 5 hours after treatment. Radioactivity was present in treated flies as tepa or aziridinyl metabolites; radioactive metabolites in the excreta did not contain aziridinyl groups. Radiometric and colorimetric determinations indicated that treated flies retained about 9 and 5%, respectively, of the injected dose over prolonged periods. Radioactivity was transferred to female flies by copulation with treated males. Because this radioactivity was found within the female body and not on its surface, we concluded that the transfer was by copulation rather than by body contact. However, no detectable radioactivity was found in the sperm or the seminal fluid present in the spermathecae of inseminated females. An electron microscopic scrutiny of house fly sperm failed to reveal any structural changes brought about by the chemosterilant.

Steroid metabolism in the rabbit. Biliary and urinary excretion of metabolites of [4-14C]progesterone

1. [4-(14)C]Progesterone was administered intravenously to anaesthetized male and female New Zealand White rabbits as a single injection or as a 45-60min. infusion. 2. After a single dose about 60% of the radioactivity was recovered in 6hr., and twice as much radioactivity was present in bile as in urine. After infusion total recovery of radioactivity was only about 40% in 6hr., but the relative proportions of metabolites in bile and urine were about the same as after a single dose. 3. Bile and urine samples were hydrolysed successively by beta-glucuronidase, cold acid and hot acid. 4. In bile the major proportion of metabolites appeared in the glucuronide fraction; in urine beta-glucuronidase hydrolysis yielded the greatest amounts of ether-extractable radioactivity, but the greatest proportion of radioactivity could not be extracted by ether from an alkaline solution of the hydrolysed urine. 5. There was no apparent difference in the quantity or distribution of metabolites excreted by male and female animals.