Jitsuya Takada

Insulin-mimetic vanadyl—dithiocarbamate complexes

Abstract As candidates for insulin mimetics, we prepared five vanadyl—dithiocarbamate complexes with VO(S 4 ) coordination mode, and determined their structures by elemental analysis, visible absorption, IR and electron spin resonance spectra; the five complexes were bis( N,N -dimethyldithiocarbamate)oxovanadium(IV) (VO-DMD), bis( N,N -diethyldithiocarbamate)oxovanadium(IV) (VO-DED), bis(pyrrolidine- N -dithiocarbamate)oxovanadium(IV) (VO-PYD), bis( N -methyl, N ′- d -glucamine-dithiocarbamate)oxovanadium(IV) (VO-MGD) and bis(sarcosine- N -dithiocarbamate)oxovanadium(IV) (VO-SAD). The insulin-mimetic activities were evaluated by in vitro and in vivo experiments. These complexes inhibited the release of free fatty acid (FFA) from isolated rat adipocytes, similar to the action of insulin. Among them, VO-PYD and VO-SAD complexes were found to be the most effective. In addition, the VO-PYD complex promoted the incorporation of glucose in rat L6 muscle cells. Based on these in vitro observations, both VO-PYD and VO-SAD complexes were given to streptozotocin-induced diabetic rats (STZ-rats) intraperitoneally or orally. Serum glucose levels of STZ-rats dropped from hyperglycemic levels to the normal range within 1 or 2 days after both intraperitoneal and oral administrations of the complexes. To understand the insulin-mimetic action of the VO-PYD complex, the organ distribution of vanadium was investigated. In normal rats treated with VO-PYD complex, vanadium was distributed in almost all tissues, indicating that the action of vanadium is not peripheral. In addition, vanadium was found in bone and kidney when VO-PYD was given. On the basis of these results, the VO-PYD complex is indicated to be a good agent to treat insulin-dependent diabetes in experimental animals.

Partition of divalent and total manganese in organs and subcellular organelles of MnCl2-treated rats studied by ESR and neutron activation analysis

The possibility that Mn2+ is converted to other valency states in vivo was examined by measuring the ratio of Mn2+, determined by ESR, to total manganese, determined by neutron activation analysis combined with chemical separation, in various organs of control rats and rats treated with MnCl2. In control rats, the total manganese content was high in the thyroid, hypophysis, adrenal, pancreas, liver and kidney, but the Mn2+ contents of these organs were low. In rats treated with Mn2+, the total manganese contents of all organs increased, but the Mn2+ contents still remained low. With regard to subcellular distribution, the total manganese content was high in the nuclear and mitochondrial fractions of the liver and kidney, and in the microsomal and supernatant fractions of the pancreas. The ratio of Mn2+ to total manganese was relatively high in the microsomes of the liver and kidney of control rats, and in the nuclear fraction of the pancreas of Mn2+-treated rats. Thus, the distribution and behavior of manganese in the pancreas were different from those in other organs. Purified liver nuclei and mitochondria were demonstrated to contain manganese, indicating that manganese is tightly bound in each cellular compartment.

TRACE ELEMENTS IN LAND PLANTS! CONCENTRATION RANGES AND ACCUMULATORS OF RARE EARTHS, Ba, Ra, Mn, Fe, Co AND HEAVY HALOGENS

More than 2000 samales of land plant leaves, mostly of tree, have been analyzed by neutron activation analysis in order to find out macroscopic relations between distributions of chemical elements in plants and soil characteristics. The distributions of the elements in plants were also examined from the view point of botanical taxonomy or phylogeny. New species which accumulate Co, rare earths, Ba, Ra, heavy halogens and some other elements have been found. Capability or potentiality for accumulating elements could be related to higher ranks of taxonomy, that is, genus or family. The nature of soil is also found to have profound effects on the extent of accumulation of elements in plants.

DNA cleavage by hydroxyl radicals generated in a vanadyl ion-hydrogen peroxide system

Vanadyl ion (+4 oxidation state) has been shown to be an effective agent for chemoprotection of cancers in animals. For understanding the mechanism, distribution of vanadium was studied. More vanadium was found to accumulate in the nuclei of the liver of rats when it was given as vanadyl sulfate than when it was given as sodium vanadate (+5 oxidation state). The reactivity of vanadyl ion with DNA was investigated by the DNA cleavage technique and the reaction mechanism by ESR spectroscopy. Incubation of double-strand DNA with vanadyl ion and hydrogen peroxide resulted in marked concentration- and pH-dependent DNA cleavage. Studies by the ESR spin-trap method demonstrated that hydroxyl radicals are generated during the reactions of vanadyl ion with hydrogen peroxide. Thus the antineoplastic action of vanadyl ion is proposed to be due to DNA cleavage by hydroxyl radicals generated in the cells.

A theoretical study on the zone mobility-pH curve in paper electrophoresis of low molecular weight compounds with a dissociable proton and its application to phosphorus compounds

Abstract It was found that the zone mobility of a compound with dissociable proton plotted against the pH value of the background solution is approximately expressed by a hyperbolic tangent function. By the use of this relation, we can easily draw the zone mobility-pH value of the background solution is approximately expressed by a hyperbolic tangent function. By the use of this relation, we can easily draw the zone mobility-pH curve of migrating species and estimate the consecutive dissociation constants. The relationships between the mobility and the molecular weight or the hydrated ionic radius were also discussed. Jokls equation is only applicable to the first dissociation of a migrating substance and the deviation increases with increasing charge number because of the hydration increment. After considering the hydration ratio, we proposed a modification of the equation. The observed relative zone mobility-pH curves of phosphorus compounds such as phosphorus oxyacids, phenylphosphorus compounds and phosphoric esters of hexoses or inosines were in fair agreement with the calculated ones. The equation proposed is useful in practice for the estimation of the dissociation constant and/or molecular weight of an unknown sample.

Radioactivation analysis of hair a means of biological monitoring of the environment

With the aim of indicating environmental pollution effects by heavy metals on humans using hair, nondestructive activation analysis was applied to 382 normal Japanese hair samples (background level). Elemental contents of hair could be determined for Ag, Al, As, Br, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, I, K, La, Mg, Mn, Na, S, Sb, Sc, Se, Sm, Ti, V and Zn. As these elements in hair have wide concentration ranges, the differences in concentrations distribution between groups (sex, age, permanent treatment and regional difference) are discussed. A method for hair sampling is presented.

ELEMENT CONTENT IN A NUMBER OF PLANT LEAVES AND ACCUMULATION OF SOME ELEMENTS IN TYPICAL PLANT SPECIES : A CASE OF OKAYAMA PREFECTURE

Content of 40 elements in plant leaves, soils and rocks collected from several sampling sites in Okayama Prefecture was analyzed by instrumental neutron activation analysis using the Research Reactor of Kyoto University. Of these, 16 elements were taken up, and the relationship among their amounts in plants, rocks and soils was discussed, focusing mainly on the essential elements of higher plants and related elements in the periodic table. Although most element contents in plant were different among species, the mediam values of the most non-essential elements in the leaf were lower than the contents in the soil and rock samples. However, essential elements showed significantly higher median values than those in the soil and rock samples. Most element contents in leaves showed a logarithmic normal distribution. The normal distribution was observed in most essential elements except for zinc, while non-essential elements did not show a normal distribution. The results obtained by analysis of variance, showed that the plant species studied could be divided into four major groups, namelyDicotyledoneae, Monocotyledoneae, Gymnospermae andPteridophyta. In general,Dycotyledoneae andPteridophyta had higher element contents thanMonocotyledonaeae andGymnospermae.

Gamma-ray energies of Se-85 and Se-86

The aim of the study described was to separate Se from other flssion products rapidly by paper electrophoresis, and to measure the unknown gamma -ray energies of the short-lived Se nuclides and their relative intensities. Details are given of the experimental procedure, and results are shown tabulated. (Uk)

Trace Elements with Large Activation Cross Section in Concrete Materials in Japan

Amounts of trace elements with large activation cross section in concrete materials were measured to offer the basic data for developing of low activation concrete. From the measurements, the quantities of the activated radioactivities in biological shielding concrete were measured and evaluated for the clearance level. The average concentrations of 60Co, 152Eu and 134Cs formed in concrete were 21.9, 1.08 and 3.21 ppm, respectively. The combination of the concrete materials for the most lowering concentrations of 60Co, 152Eu and 134Cs was the limestone as aggregate and the white Portland cement produced in specific places. The most lowering concentrations of this limestone concrete were 0.16, 0.049 and 0.060 ppm, respectively. The limestone concrete was excellent as biological shielding concrete, because the neutron shielding effect was excellent a little compared with ordinary concrete. If this concrete used for biological shielding concrete, concrete waste will be able to handle as follows. Usage of this limestone low-activated concrete makes almost all concretes satisfy the clearance level for 60Co after 20 yr cooling from decommissioning. In respect of 152Eu, radioactivation quantity in the biological shielding concrete is reduced up to a half of the average value or less. With regard to 134Cs, all concrete satisfies the clearance level.

Losses of elements in plant samples under the dry ashing process

Losses of trace elements in plant samples after dry ashing were investigated. Plant samples were heated in crucibles at 105–600°C for 0.5–24 hours in a muffle furnace. The amounts of elements remaining after heating were determined by INAA. The amounts of Cl and Br decreased over the range 200–400°C in all samples, especially in stem samples. The amount of Na increased over the range 450–600°C, possibly because of contamination from the crucibles. Dry ashing is suitable for analyzing most elements in plant samples.