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PubMed1981

Studies on nitrosamine metabolism. III. Comparison of the subcellular distribution of radioactivity in tissues of RFM and BALB/c mice following administration of [14C]diethylnitrosamine.

The tissue distribution of radioactivity in male RFM and BALB/c mice was investigated following a single dose of [14C]-labeled diethylnitrosamine (DEN). The radiolabel was associated with all the subcellular fractions, and the majority of the radioactivity was located in the cytosol fraction. The majority of the radiolabel was usually eliminated from the fractions within 16-24 hrs after [14C]DEN administration.

Animals↗
PubMed1980

Lymphatic clearance of radioactive sulfur colloid.

Lymphatic clearance of radioactive sulfur colloid is measured in the hind limb of five mongrel dogs. A solid state Si(Li) detector is placed onto the skin to continuously record activity over the site of subcutaneous injection. Decrease in activity follows an exponential decay which is modeled as a dual decay occurring from both the radioactive decay of the tracer and the lymph clearance of the tagged sulfur colloid. The calculated decay constants for lymph clearance flow per tissue volume result in a mean value of 0.233 +/- 0.077 ml/hr/ml which is consistent with results of other investigators. Adjacent lymph nodes are monitored with a scintillation detector to show that the colloid is absorbed by the lymph vessels. The carotid artery and liver are similarly monitored to show that there is little or no capillary absorption of the tagged colloid.

Animals↗
PubMed1980

Preliminary results on the total radioactivity distribution upon parenteral administration of 14C-coumarin to DBA/2 mice.

The time related distribution patterns of coumarin (C) and its main metabolite 7-hydroxycoumarin (7-HC) were studied in DBA/2/lac mice following retroorbital injection of 14C-labelled C. The total radioactivity was determined as counts per minute per ml or g wet weight over a period of 60 min. In blood, brain, heart, lung, muscle and spleen peak concentrations were observed 2.5 min after dosing. The liver and kidney showed the greatest accumulation with peak concentrations being reached after 10 min. Blood and brain concentrations were equal. Unmetabolized C was found in all organs studied; 7-HC was found in all organs but brain, and the glucuronide of 7-HC was found in all organs but brain and spleen. Apparently C crosses the blood brain barrier but the metabolites do not. The decay of the total radioactivity versus time appears to be best fitted to a two-compartment model for brain, heart, lung, muscle, and spleen, and to a one-compartment model for blood, liver and kidney. The terminal half-life in blood was 0.24 h.

Animals↗
PubMed1980

Pharmacokinetics and metabolic disposition of 14C-metronidazole-derived radioactivity in rat after intravenous and intravaginal administration.

Urinary metabolites and the pharmacokinetics of radioactivity derived from 14C-metronidazole (14C-MTZ) were determined after intravenous (iv) or intravaginal (ivg) administration of 10 mg/kg to adult rats. Following iv or ivg administration, the disappearance of 14C from blood followed the kinetics of a two-compartment open-system model. The blood half-lives of 14C during the beta-phase were 10.9 +/- 1.6 and 13.6 +/- 4.2 hr, after iv and ivg administration, respectively. After ivg application, the MTZ-derived radioactivity was detected in tail blood at 5 min, peaked at 1 hr, declined rapidly to 6 hr and more slowly thereafter. The vaginal absorption half-life of 14C-MTZ was 0.28 +/- 0.09 hr. About 12% of the administered dose remained in the vagina after 1 hr and 1.5% after 24 hr. At 24 hr, the tissue distribution and concentration of 14C were similar in iv and ivg dosed rats, the highest 14C concentration being present in the kidneys and lowest in the fat. The percentages of the dose excreted in 24 hr in the urine and feces were 58 and 15 after iv administration, compared to 37 and 40 after the ivg route, respectively. Unchanged 14C-MTZ and five of its metabolites were detected in the urine irrespective of the route of administration. The results show that metronidazole is rapidly absorbed through the vaginal mucosa of the rat and the metabolism and excretion of this chemotherapeutic agent are influenced by the route of administration.

Animals↗
PubMed1980

[Lymphoedema of the upper limb following surgery or radiotherapy. Investigation by indirect radioactive lymphography (author's transl)].

Indirect radioactive isotope lymphography using intravenous 99 m Tc-labelled colloidal antimony sulfide was performed on 76 patients with lymphoedema of the upper limb consecutive to surgery or radiotherapy. The time required to reach 50% of maximum radioactivity was taken as index of the lymphatic flow rate, and the patients were divided into 3 groups depending upon the index (< 20 min; 20-60 min; > 60 min). It appears that in huge lymphoedemas the lymphatic flow rate index may remain subnormal, owing to associated veno-occlusive oedema. This non-invasive method provides data on the site and, frequently, on the nature and importance of lymph blockade. It might also help to predict the efficacy of a new drug currently under study.

Arm↗
PubMed1980

[Problems relating to the use of radioactively labelled bacteria in animal experiments. 3. Distribution of activities in mice, following parenteral administration of Pasteurella multocida labeled with various radionuclides].

When radioactively labelled fully developed Pasteurella (P.) multocida antigens were parenterally applied to mouse, through intravenous, intraperitoneal or subcutaneous routes, activity distribution was found to depend both the technique of application and the radionuclide used. This has given rise to the conclusion that activity distribution could be equated with whole-germ distribution only under certain conditions. Experimental antigen distribution, accordingly, reflected a complex process in which transport, location, and metabolism of bacteria had to be considered as being in conflict with the given host organism. Iodine labelled 125 was split off bacteria at relatively high rate and accumulated in the thyroid gland. When 59Fe was used, interpretation of distribution was rendered more difficult by propagation of iron through the organs of the host. Relatively favourable data were obtainable from the use of 3H or 14C which could be used in the form of nucleic acid precursors (orotic acid) in labelling Pasteurella. Intraperitoneal and intravenous forms of administration were found to be the same for intra-organic activity distribution. Retention of activity in liver, spleen, and lung was recordable and established from all the reviewed techniques for the application of P. multocida complete antigen. While maximum concentrations were measured between the first and third days, activities still were detectable after 14 days (period under review). Relatively high radioactivity was recordable from the digestive tract, within short time from the use of the parenteral procedures tested. This seemed to suggest passage of complete or incomplete P. multocida antigen through the mucous membranes of the gastro-intestinal tract.

Animals↗
PubMed1994

A non-radioactive, sensitive method for the detection of DNA fragmentation in apoptotic cells (rat pheochromocytoma PC12 and rat cortical cells).

A new method is described which is suitable for reliably analysing apoptotic fragmentation in small amounts of DNA. After isolation, DNA was labelled with biotin-4-dUTP using Klenow polymerase. Then DNA was size-separated by agarose gel electrophoresis, blot transferred and subsequently visualized by the streptavidin alkaline phosphatase-BCIP/NBT procedure. This non-radioactive method was used to detect apoptotic DNA in rat pheochromocytoma PC12 cells, treated with tributyltin (1 nM). While only 30 ng of DNA is required for analysis of apoptotic DNA using the new blot technique, 100-fold more material is needed to identify the fragmentation of DNA after separation by agarose gel electrophoresis and direct staining with ethidium bromide. In a further set of experiments, rat cortical cells were incubated with human immunodeficiency virus type 1 viral glycoprotein of M(r) of 120 kDa (gp120) to induce apoptosis. More than 0.3 ng of gp 120/ml are required to detect apoptotic DNA by the direct procedure; only 0.1 ng gp120/ml or less were sufficient to document clear DNA fragmentation using the non-radioactive blotting technique described here. These results demonstrate that the new procedure can be used to analyse very small amounts of apoptotic DNA and shows that gp120-induced apoptosis can be measured at low concentrations of the viral protein.

Animals↗
PubMed1994

[Non-radioactive SSCP for the detection of androgen receptor gene mutation--a diagnostic tool for androgen resistance].

Point mutations in the androgen receptor gene cause androgen insensitivity syndromes, clinically characterized by masculinization defects in karyotypic males due to endorgan resistance to androgenic steroids. Characterization of these mutations with single strand conformation polymorphism analysis utilizing radioactive PCR can serve as a diagnostic tool for molecular subclassification of these syndromes. It is the basis for genetic counseling and for therapeutic decisions. Here we report an improved non-radioactive single strand polymorphism analysis for rapid detection of androgen receptor gene mutations in affected individuals. In addition to previously reported mutations, 9 patients with clinical features of androgen resistance were studied. While one insertion mutation was detected, in all other patients different point mutations initiating amino acid substitutions were characterized.

Amino Acid Sequence↗
PubMed1978

[Surgery in radioactive patients (author's transl)].

The authors discuss some legal aspects and protection problems relative to surgical procedures involving radioactive patients, also in the light of recent European guidelines. They analyse in particular the radiation risk associated with the more common cases concerning radioactive substances that are administered for diagnostic purposes. This study affords a preliminary evaluation of the risk inherent in such surgery, in the light of experimental measurements.

Humans↗
PubMed1995

Fluorescent vs. radioactive microsphere measurement of regional myocardial blood flow.

OBJECTIVES: This study compared simultaneous regional myocardial blood flow (RMBF) measurements using fluorescent microspheres (FM) and radiolabeled microspheres (RM). The utility of an internal standard during processing was also examined. METHODS: Paired FM and RM were injected into the left atrium of 9 anaesthetised rabbits. RMBF was altered by use of either regional ischaemia or (-)-N6-(2-phenylisopropyl)-adenosine. Radioactivity of blood reference and tissue samples was quantitated using standard methods. Samples were then digested with potassium hydroxide and microspheres recovered by vacuum filtration, with an additional label of FM as the internal standard. FM labels were extracted using Carbitol acetate and quantitated using fluorescence spectroscopy. Agreement between the fluorescent and radioactive methods was assessed using both orthogonal regression and difference-against-mean analyses. RESULTS: Using recovery-uncorrected data, the slope of the orthogonal regression of RM and FM-determined RMBF was not statistically different from 1, but the intercept was statistically different from 0 [-0.03(0.01), P = 0.005] and the mean RMBF by each method differed from one another [1.24(0.08) vs. 1.17(0.08) ml.min-1.g-1, P = 0.0002]. The mean +/- 2 s.d. of the differences of RMBF (RM minus FM) was +0.07 +/- 0.30 ml.min-1.g-1. Although recovery of FM from tissue averaged 97.6(1.2)%, use of the internal standard to correct for losses substantially improved the agreement between RM and FM-determined RMBF: the orthogonal regression slope was not statistically different from 1, the intercept was not statistically different from 0, and the means of the flows were not different. The mean +/- 2 s.d. of the differences of RMBF was -0.01 +/- 0.22 ml.min-1.g-1. The internal standard also improved RMBF estimates from samples with simulated large spillage during processing. CONCLUSION: Fluorescent microspheres are an equivalent alternative to radiolabeled microspheres for the estimation of RMBF. Although the overall recovery of microspheres using this technique was high, use of an internal standard is recommended for correction of random losses.

Animals↗
PubMed1976

[Biological changes in 88 cases of Basedow's disease treated by radioactive iodine].

Biological abnormalities, in particular increased T3 and sometimes TSH, are frequently found in thyrotoxic patients treated with radioactive iodine and subsequently enthyroid. A high T3, associated with an increase in FT4 and a low TSH precedes a relapse. An increase in TSH may indicate progression towards hypothyroidism; even if FT4 and T3 levels are within normal limits. Caution must be exercised before affirming that an increased TSH with a high T3 and normal FT4 is indicative of thyroid equilibrium. At all events, the risk of hypothyroidism despite the use of small doses of radioactive iodine is such that the classical limit for the treatment of patients with thyrotoxicosis should be increased beyond the age of 40. In patients with a high TSH despite being clinically euthyroid, the use of thyroid extract in low dosage (50 mg/day) would appear to be desirable in avoiding the subsequent development of hypothyroidism.

Age Factors↗
PubMed1994

Chromosome aberrations after treatment with radioactive iodine for thyroid cancer.

The study aimed to investigate whether the determination of chromosome aberrations in circulating blood lymphocytes could be useful to assess whole-body exposure from radioactive iodine released accidentally. Ten patients treated with two doses of 1850 MBq of 131I given 24 h apart for thyroid cancer were studied for chromosome aberrations (dicentrics) in blood samples taken before and at various times after exposure. The increase in the yield of aberrations caused by the exposure to iodine was small but statistically significant. Compared to published values for whole-body doses after such treatment, this increase appears to be somewhat smaller than expected from dose-effect relationships obtained for an acute exposure of lymphocytes in vitro or in vivo, a fact which could be explained by the low dose rate of the 131I exposure. Thus, in situations where a population was exposed as a result of the release of radioactive iodine, a determination of chromosome aberrations in blood lymphocytes would not appear to be very useful to determine exposure from iodine.

Chromosome Aberrations↗
PubMed1975

[Incorporation of radioactive leucine into lizard epididymis proteins. Study during the sexual cycle and after injection of testosterone to untreated or castrated animals].

Lizard epididymis activity during the reproductive cycle and after testosterone administration results in a marked increase of radioactive leucine incorporation in vivo and in vitro. The electrophoretic distribution of soluble proteins shows different peaks of radioactivity. Comparison between histological response and pattern of electrophoresis suggests that one of these peaks may correspond to an activity of secretion.

Animals↗
PubMed1976

[Distribution, absorption and elimination of radioactivity following oral and intravenous application of 2'-14C-labelled cyproterone acetate to rhesus monkeys (author's transl)].

13 female rhesus monkeys were given 2'-14C-cyproterone acetate i.v. and p.o. The radioactivity of the blood plasma and the elimination in urine and faeces were then measured at suitable intervals for a period of 12 days. After i.v. administration the time for distribution in the body amounted to 8 h. The extrapolated initial concentrations in the equilibrium to distribution amounted to 0.68% of the administered dose in the plasma volume, and the theoretical volume of distribution was 5 times the body volume. After oral administration the maximum levels in the plasma were reached on an average 13 h after administration. They attained the level of the extrapolated initial concentration after i.v. administration. The compound was eliminated from the body with a radioactive half-life of 1.6 to 1.8 days, irrespective of the route of administration. The mean ratio of elimination urine: faeces was approximately 0.7 for all animals. After oral administration 81% of the dose was absorbed on the average.

Administration, Oral↗
PubMed1993

Sequence analysis of low-molecular-weight RNAs by the use of non-radioactive labeling.

A new procedure for non-radioactive labeling of the 3'-terminal -OH was developed to facilitate the sequencing works on low-molecular-weight RNAs. At first, biotinylated pCp (cytidine 3',5'-bisphosphate) was synthesized and ligated to the 3'-terminal of yeast tRNA(Phe) with the aid of RNA ligase. Although the labeling efficiency was high enough, this labeling resulted in a lack of the sequence ladders around the 3'-terminal 10 nucleotides. A longer oligonucleotide, p(dC)(dT)16-Biotin was designed to overcome this defect and proved to be a better non-radioactive 3'-labeling probe.

Biotin↗
PubMed1976

[Interpretation of autoradiographs and images of biological objects with the electronically operating image analyzer "Densitron II'". 2. Evaluation of the specific and total radioactivity of single cells (author's transl)].

Using the TV image analyzer Densitron, transparencies and areas can be measured by the grey value discrimination method equidensitometry. The time, necessary for one measurement, is approximately 1 min, the standard deviations do not exceed 2%. 2. Also microscopical objects such as single cells can be analyzed by this method. We measured photo-blackings and areas in autoradiographs of goldfish brain-sections after injection of 3H-phenylalanine. As a parallel, blacking and area calibration curves were obtainable and allowed a conversion of the relative values into absolute ones. 3. Using this conversion method, neurons of different brain regions were in the range from 104 to 1476 mum2 in area and from 4.17 to 14.43 muCi-cm-3 in specific radioactivity. After 10 repeated measurements of one and the same cell, the standard deviations of the absolute values were 6 and 4.5%, respectively, on an average. 4. On the basis of these and additional values (thickness of section, number of sections per cell), calculations of the total radioactivity of a cell section or the whole cell can be made.

Animals↗
PubMed1994

Discriminated release of a hippurate-like radiometal chelate in nontarget tissues for target-selective radioactivity localization using pH-dependent dissociation of reduced antibody.

UNLABELLED: To achieve high and selective target radioactivity localization by monoclonal antibodies (Mabs) labeled with metallic radionuclides, the discriminated release of a hippurate-like radiometal chelate in nontarget tissues was performed using chemically modified Mabs. METHODS: The disulfide bonds of a Mab against osteogenic sarcoma (OST7, IgG1) were reduced and 67Ga chelate of succinyldeferoxamine (SDF) was conjugated proximal to the Mab molecule via an ester bond with exposed thiol groups (67Ga-DFO-MESS-redOST7), which would impair esterase access to the ester bond of 67Ga-DFO-MESS-redOST7 due to the steric interference induced by bulky antibody molecule, stabilizing the ester bond in plasma and on the target cell's surface. Gallium-67-SDF was also conjugated to OST7 via an ester bond with 2-iminothiolane to render the ester bond in a position distal from the OST7 molecule (67Ga-DFO-MESS-IT-OST7). RESULTS: Although SDS-PAGE analyses of 67Ga-DFO-MESS-redOST7 showed a partial cleavage of its disulfide bonds, size-exclusion HPLC and cell binding assays indicated that the IgG structure and immunoreactivity of this conjugate were preserved in a neutral buffer and plasma of the systemic circulation. CONCLUSION: The present radiochemical design of an antibody utilizing pH-dependent dissociation would constitute a promising approach in establishing selective target radioactivity localization by Mabs.

Animals↗