Modification of catalase and MAPK in Vicia faba cultivated in soil with high natural radioactivity and treated with a static magnetic field

The effects of a static magnetic field (SMF) and high natural radioactivity (HR) on catalase and MAPK genes in Vicia faba were investigated. Soil samples with high natural radioactivity were collected from Ramsar in north Iran where the annual radiation absorbed dose from background radiation is higher than 20 mSv/year. The specific activity of the radionuclides of ²³²Th, ²³⁶Ra, and ⁴⁰K was measured using gamma spectrometry. The seeds were planted either in the soil with high natural radioactivity or in the control soils and were then exposed to a SMF of 30 mT for 8 days; 8 h/day. Levels of expression of catalase and MAPK genes, catalase activity and H₂O₂ content were evaluated. The results demonstrated significant differences in the expression of catalase and MAPK genes in SMF- and HR-treated plants compared to the controls. An increase in catalase activity was accompanied by increased expression of its gene and accumulation of H₂O₂. Relative expression of the MAPK gene in treated plants, however, was lower than those of the controls. The results suggest that the response of V. faba plants to SMF and HR may be mediated by modification of catalase and MAPK.     

Radionuclides content in grape molasses soil samples from Central Black Sea region of Turkey

The activity concentrations of radionuclides in grape molasses soil samples collected from Zile (Tokat) plain in the Central Black Sea region of Turkey were measured by using gamma spectrometer with a NaI(Tl) detector. Also, the concentrations of ²²²Rn in soil samples and air were estimated essentially taking the activity concentrations of ²²⁶Ra measured in soil samples. Grape molasses soil samples with calcium carbonate content are used for sedimentation for making molasses in this region. The average activity concentrations of ²³²Th, ²²⁶Ra, ⁴⁰K, and ¹³⁷Cs were found as 62 ± 2, 68 ± 3, 479 ± 35, and 8.0 ± 0.3 Bq kg^?1, respectively. The average concentrations of ²²²Rn in soil samples and air were estimated to be 50 kBq m^?3 and 144 Bq m^?3. From the activity concentrations, absorbed gamma dose rate in outdoor air (D), annual effective dose from external exposure (E_E), annual effective dose from inhalation of radon (E_I), and excess lifetime cancer risk (ELCR) were estimated in order to assess radiological risks. The average values of D, E_E, E_I, and ELCR were found to be 90 nGy h^?1, 110 μSv y^?1, 1360 μSv y^?1, and 4 × 10^?4, respectively.     

核酸探针中放射性同位素的快速检测

利用尼龙膜作为介质,以0．4mol／L的NaOH为层析液,进行膜上层析,分离经放射性同位素标记的核酸探针和未掺入的放射性游离单核苷酸,再经放射性强度测定即可计算出标记后的核酸探针的放射性比活。方法简单快捷,产生的放射性废物少,完全可以替代经典的三氯乙酸沉淀法及滤膜吸附法。     

Design,synthesis and biological evaluation of negatively charged 111In-DTPA-octreotide derivatives

Our previous studies indicated that ¹¹¹In-diethylenetriaminepentaacetic acid (¹¹¹In-DTPA)-octreotide derivatives with an additional negative charge by replacing N-terminal d-phenylalanine (d-Phe) with an acidic amino acid such as l-aspartic acid (Asp) or its derivative exhibited low renal radioactivity levels when compared with ¹¹¹In-DTPA-d-Phe¹-octreotide. On the basis of the findings, we designed, synthesized and evaluated two Asp-modified ¹¹¹In-DTPA-conjugated octreotide derivatives, ¹¹¹In-DTPA-Asp¹-octreotide and ¹¹¹In-DTPA-Asp⁰-d-Phe¹-octreotide. While ¹¹¹In-DTPA-Asp¹-octreotide showed negligible AR42J cell uptake, ¹¹¹In-DTPA-Asp⁰-d-Phe¹-octreotide exhibited AR42J cell uptake similar to that of ¹¹¹In-DTPA-d-Phe¹-octreotide. When administered to AR42J tumor-bearing mice, ¹¹¹In-DTPA-Asp⁰-d-Phe¹-octreotide exhibited renal radioactivity levels significantly lower than did ¹¹¹In-DTPA-d-Phe¹-octreotide at 1 and 3 h post-injection. No significant differences were observed in tumor accumulation between ¹¹¹In-DTPA-Asp⁰-d-Phe¹-octreotide and ¹¹¹In-DTPA-d-Phe¹-octreotide after 1 and 3 h injection. The findings in this study suggested that an interposition of an Asp at an appropriate position in ¹¹¹In-DTPA-d-Phe¹-octreotide would constitute a useful strategy to develop ¹¹¹In-DTPA-d-Phe¹-octreotide derivatives of low renal radioactivity levels while preserving tumor accumulation.     

Radiological toxicity of some fish and meat tissues consumed in southwestern Nigeria

The activity concentrations of natural radionuclides in 30 fish tissues and 30 meat organs have been determined using high purity germanium (HPGe) detector. For the fish tissues, the mean activity concentrations of ²³⁸U and ²³²Th were highest in Catfish (Clarias gariepinus) with values of 5.31 ± 1.30 and 6.09 ± 0.91 Bq/kg, respectively. The lowest mean activity concentrations of ²³⁸U and ²³²Th were seen in Titus (Scomberomorus tritor) and Croaker (Micropogonias undulatus), Croaker with values of 1.51 ± 2.08 and 64.42 ± 6.33 Bq/kg, respectively. The mean activity concentration of ⁴⁰K was highest in Micropogonias undulatus and lowest in Tilapia (Oreohronis niloticus) with values of 64.42 ± 6.33 and 6.53 ± 0.98 Bq/kg. For the meat organs, the highest mean activity concentration of ²³⁸U, ²³²Th, and ⁴⁰K was highest in kidney, liver, and heart, respectively with values of 2.82 ± 0.47, 4.57 ± 0.69, and 52.07 ± 7.81 Bq/kg. Small intestine had the lowest mean activity concentrations of ²³⁸U and ²³²Th with values of 1.14 ± 0.16 and 0.89 ± 0.08 Bq/kg, respectively. Beef had the lowest mean activity concentration of ⁴⁰K with a value of 17.61 ± 2.14 Bq/kg.     

Incorporation of 14C-labelled polyunsaturated fatty acids by juvenile turbot, Scophthalmus maximus (L.) in vivo

The ability of juvenile turbot, Scophthalmus maximus (L.), to elongate and desaturate various polyunsaturated fatty acids (PUFA) was examined in relation to their lipid composition. Triacylglycerols were the most abundant lipid class present in the fish and phosphatidylcholine was the predominant phospholipid. In all lipid classes examined the levels of (n-3) PUFA exceeded that of (n-6) PUFA. 18C PUFA were minor components in comparison with 20:5(n-3) and 22:6(n-3). 20:4(n-6) was present in highest concentration in phosphatidylinositol in which it accounted for 16.9% of the fatty acids. When the fish were injected with either ¹⁴C-labelled 18:2(n-6), 18:3(n-3), 20:4(n-6), 20:5(n-3) or 22:6(n-3) the highest percentage recovery of radioactivity (69%) in body lipid was observed with 22:6(n-3). With all labelled substrates free fatty acids contained only a small proportion of the total recovered radioactivity whereas triacylglycerols were highly labelled. Phosphatidylcholine/sphingomyelin was the most highly labelled polar lipid fraction. With ¹⁴C-20:4(n-6) as injected substrate, 23.2% of the radioactivity recovered in total lipid was present in phosphatidylinositol in comparison with less than 6% with the other substrates. Only small proportions of radioactivity from ¹⁴C-18:2(n-6) and ¹⁴C-18:3(n-3) were recovered in the 20 and 22C fatty acids of triacylglycerols and total polar lipid. With ¹⁴C-20:5(n-3) as substrate, 27 and 33% of the total radioactivity recovered in the fatty acids of triacylglycerols and polar lipids respectively was present in 22C fatty acids. The corresponding values for ^l4C-20:4(n-6) as substrate were 19 and 18%. The results confirm the limited capacity of turbot to convert 18C PUFA to longer chain PUFA but demonstrate their ability to synthesize 22C PUFA from 20C PUFA. They also suggest a small but specific requirement for 20:4(n-6).     

Radionuclide-induced evolution of DNA and the origin of life

Summary Artesian groundwaters of high radionuclide concentration are ubiquitous and may have provided the large, sustained energy sources that were required to drive the multistage process of DNA and primordial cell evolution. The rapid, early development of the genetic code as well as its degeneracy can be attributed to exceptionally high radiation-induced mutation rates in this unique environment. The ability of double-strand DNA to direct enzymatic repair of radiation damage to single strands contributed importantly to its selective evolution. It is postulated that the polymerization of nucleotides took place at elevated temperatures within -particle tracks of high ion and free-radical density, followed by rapid quenching to ambient conditions. It also is evident that radiation resistance and ploidy were important selection factors in cellular evolution.     

Stereoselective pharmacokinetics of [14C]-labeled KE-298, a new anti-rheumatic drug,in rats

The stereoselective pharmacokinetics of two enantiomers of [¹⁴C]-labeled KE-298 [2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanonic acid] were investigated in rats. The blood levels of radioactivity after the oral administration of (+)-(S)-[¹⁴C]KE-298 were higher than that for (−)-(R)-[¹⁴C]KE-298; the AUC of the former was approximately twice that of the latter. No significant stereoselectivity was observed in absorption rate. The tissue/plasma level ratios at 30 min after oral administration of (−)-(R)-[¹⁴C]KE-298 in the liver and kidney, the major metabolic and/or excretory organs, were 2 to 3 times higher than those for (+)-(S)-[¹⁴C]KE-298. Neither was evidence of stereoselectivity found in the excretion of radioactivity. During incubation with isolated rat hepatocytes in vitro, the metabolic rates of KE-298 enantiomers were not significantly different. Plasma protein binding 30 min after the oral administration of (+)-(S)-[¹⁴C]KE-298 and (−)-(R)-[¹⁴C]KE-298 was 99.3% and 97.0%, respectively. Comparing the unbound fraction, (−)-(R)-[¹⁴C]KE-298 was approximately 4 times higher than (+)-(S)-[¹⁴C]KE-298. In order to make clear the relationship between stereoselective pharmacokinetics and protein binding for [¹⁴C]KE-298, the comparative pharmacokinetics of (+)-(S)-[¹⁴C]KE-298 and (−)-(R)-[^14CC]KE-298 were investigated in analbuminemic rats. In these animals, no evidence of stereoselectivity was found for either blood level-time profiles or plasma protein binding. These results revealed that the stereoselective pharmacokinetics of KE-298 in rats might be due to enantiomeric differences in binding to plasma albumin. © 1996 Wiley-Liss, Inc.