放射性核素向农作物中的转移——作物及核素间的差异

绪言近几年,日本对于放射性废物的陆地保管,处置设施的建设正在向前推进。其目的,在推行建设和工作中伴随着主要的放射性物质转移过程(土壤→农作物→人体)中的安全评价。作者所研究的集团为稳定性元素或者放射性核素(以下简称RI)的示踪物试验,或是对于环境样品中稳定性元素的定量。从这两种途径估算照射剂量是日本独创的参数(沉积速度、转移系数)以及参与变化主要因素等有关方面的研究。作为RI从土壤向农作物转移的量是估算转移系数的基本参数,US-NRC Regulatory Guvide和IAEA Safety SeriesNo.57等刊载了许多元素的转移系数。然而。

Shp-2／NF-κB Pathway Mediates the Inhibition of Lipoxin A4 onIL-1β-induced Synthesis of IL-6 in Glomerular Mesangial Cells

Objective: To examine whether lipoxin A 4 (LXA 4) has an antagonistic effect on IL-1β-induced synthesis of IL-6 in glomerular mesangial cells, and to explore the molecular mechanisms of signal pathway in LXA 4 actions. Methods: The glomerular mesangial cells of rat were cultured and treated with IL-1β, with or without preincubation with LXA 4 at different concentrations. The amount of IL-6 in the supernatant of cells was analyzed by enzyme-linked immunosorbent assay(ELISA). The expressions of mRNA of IL-6 were determined by RT-PCR. The expressions of Src homology 2(SH 2) containing protein-tyrosine phosphatase 2(Shp-2) were assessed by immunoprecipitation and immunoblotting. Activities of DNA-binding of nuclear factor-kappa B(NF-κB) were measured by electrophoretic mobility shift assay(EMSA). Results: IL-1β-stimulated secretion of protein and expression of mRNA of IL-6 in mesangial cells were inhibited by LXA 4 in a dose-dependent manner. LXA 4 antagonizes the phosphorylation of Shp-2 and activities of NF-κB induced by IL-1β. Conclusion: LXA 4 antagonists IL-1β-induced synthesis of IL-6 in glomerular mesangial cells through the mechanism of Shp-2/NF-κB pathway-dependent signal transduction.

Up-regulation of intestinal nuclear factor kappa B and intercellular adhesion molecule-1 following traumatic brain injury in rats

AIM: Nuclear factor kappa B (NF-κB) regulates a large number of genes involved in the inflammatory response to critical illnesses, but it is not known if and how NF-KB is activated and intercellular adhesion molecule-1 (ICAM-1) expressed in the gut following traumatic brain injury (TBI). The aim of current study was to investigate the temporal pattern of intestinal NF-κB activation and ICAM-1 expression following TBI. METHODS: Male Wistar rats were randomly divided into six groups (6 rats in each group) including controls with sham operation and TBI groups at hours 3, 12, 24, and 72, and on d 7. Parietal brain contusion was adopted using weight-dropping method. All rats were decapitated at corresponding time point and mid-jejunum samples were taken. NF-KB binding activity in jejunal tissue was measured using EMSA. Immunohistochemistry was used for detection of ICAM-1 expression in jejunal samples. RESULTS: There was a very low NF-κB binding activity and little ICAM-1 expression in the gut of control rats after sham surgery. NF-KB binding activity in jejunum significantly increased by 160% at 3 h following TBI (P<0.05 vs control), peaked at 72 h (500% increase) and remained elevated on d 7 post-injury by 390% increase. Compared to controls, ICAM-1 was significantly up-regulated on the endothelia of microvessels in villous interstitium and lamina propria by 24 h following TBI and maximally expressed at 72 h post-injury (P<0.001). The endothelial ICAM-1 immunoreactivity in jejunal mucosa still remained strong on d 7 post-injury. The peak of NF-κB activation and endothelial ICAM-1 expression coincided in time with the period during which secondary mucosal injury of the gut was also at their culmination following TBI. CONCLUSION: TBI could induce an immediate and persistent up-regulation of NF-κB activity and subsequent up-regulation of ICAM-1 expression in the intestine. Inflammatory response mediated by increased NF-κB activation and ICAM-1 expression may play an important role in the pathogenesis of acute gut mucosal injury following TBI.

Macrophage colony-stimulating factor expressed in non-cancer tissues provides predictive powers for recurrence in hepatocellular carcinoma

AIM To investigate the role of macrophage colony-stimulating factor(M-CSF) in patients with hepatocellular carcinoma(HCC) after surgery. METHODS Expression of M-CSF, distribution of M2 macrophages(Mφs), and angiogenesis were assessed in the liver, including tumors and peritumoral liver tissues. The prognostic power of these factors was assessed. Mouse isolated hepatic Mφs or monocytes were cultured with media containing M-CSF. The concentration of vascular endothelial growth factor(VEGF) in media was assessed. Furthermore, the role of the M-CSF-matured hepatic Mφs on proliferation of the vascular endothelial cell(VEC) was investigated. RESULTS A strong correlation between the expressions of M-CSF and CD163 was observed in the peritumoral area. Also, groups with high density of M-CSF, CD163 or CD31 showed a significantly shorter time to recurrence(TTR) than low density groups. Multivariate analysis revealedthe expression of M-CSF or hepatic M2Mφs in the peritumoral area as the most crucial factor responsible for shorter TTR. Moreover, the expression of M-CSF and hepatic M2Mφs in the peritumoral area had better predictable power of overall survival. Values of VEGF in culture media were significantly greater in the hepatic Mφs compared with the monocytes. Proliferation of the VEC was greatest in the cells co-cultured with hepatic Mφs when M-CSF was present in media.CONCLUSION M-CSF increases hepatocarcinogenesis, most likely by enhancing an angiogenic factor derived from hepatic Mφ and could be a useful target for therapy against HCC.

A variation pixels identification method based on kernel spatial attraction model and local entropy for robust endmember extraction

A variation pixels identification method was proposed aiming at depressing the effect of variation pixels, which dilates the theoretical hyperspectral data simplex and misguides volume evaluation of the simplex. With integration of both spatial and spectral information, this method quantitatively defines a variation index for every pixel. The variation index is proportional to pixels local entropy but inversely proportional to pixels kernel spatial attraction. The number of pixels removed was modulated by an artificial threshold factor α. Two real hyperspectral data sets were employed to examine the endmember extraction results. The reconstruction errors of preprocessing data as opposed to the result of original data were compared. The experimental results show that the number of distinct endmembers extracted has increased and the reconstruction error is greatly reduced. 100% is an optional value for the threshold factor α when dealing with no prior knowledge hyperspectral data.

Sinking of particulates ^(234)Th_(xs),~7Be and ^(210)Pb_(xs) in the Changjiang estuary,China

The time scale of transport and reaction processes in the ocean can be evaluated using natural radionuclides of different half-lives.In the present study,we evaluated the residence times of particulate reactive radionuclides 7 Be,210 Pb xs and 234 Th in the Changjiang (Yangtze River) estuary,which is a high turbidity estuary,in June,2006.The residence times of particulate 7 Be,234 Th xs and 210 Pb xs in the Changjiang estuary were calculated to be 0.7-20.4,0.18-4.1 and 0.6-89.8 d,respectively.The obtained residence times of those nuclides are comparable with those of other estuaries and bays.For 234 Th xs and 7 Be,the residence times decreased with increasing concentrations of suspended particulate matter (SPM);however,those of 210 Pb xs increased.Moreover,scavenging residence times of 234 Th and 7 Be increased from coast to offshore,while those of 210 Pb xs decreased.

Exotic Structures of Odd-A Carbon Isotopes in the Deformed Relativistic Mean-FieldTheory

We study contributions of the pion meson and spatial component of the omega meson in the odd-A carbon isotopes. The pion and spatial omega provide small attractions in odd-A nuclei, giving rise to considerable influences on the single-particle energies rather than the bulk properties such as total binding energies, and root-mean-square (rms) radii. The ±? (spin) splittings, arising from the spatial omega, are large in 11C and 13C and drop as the isospin rises in odd-A carbon isotopes. As an isovector, the pion can shift slightly the relative potential depth of neutron and proton, contrary to the role of the rho meson. There is a general trend that both the pion and spatial omega fields reduce with the rise of isospin in the isotopic chain. From the normal nucleus to halo nucleus, an abnormal drop of the pion or spatial omega field may occur, as can be seen in 19C, 15C, and 21C.

The Time-Effect Relationship of Central Action in Acupuncture Treatment for Weight Reduction

Purpose: To study the time-effect relationship of action of acupuncture on the satiety center of ventromedial nucleus of hypothalamus (VMH) in rats with experimental obesity. Methods: Microelectrode recording method of nerve cells and stereotaxic technique for brain were adopted with discharge frequency (Hz/s) of nerve impulse in VMH as the index, and the time-effect of acupuncture action in different periods between groups were observed. Results: Electric activity in acupuncture group was higher than that in the obesity model group (P<0.001) and the normal group (P<0.01) respectively, and the curve of acupuncture action within 2 hours showed irregular fluctuation. Conclusion: Acupuncture can increase excitability of the satiety center, with a better long-term effect.

Quasi-periodic variations of low energy cosmic rays

Cosmic rays(CR)play an important role in space weather-related studies.Their temporal variability,both of a quasi-periodic character as well as an irregular one,has been studied from ground-based direct measurements,as well as from cosmogenic nuclides,over a long time.We attempt to describe the current knowledge of selected quasi-periodicities in CR flux in the energy range above the atmospheric threshold,from direct measurements.The power spectrum density(PSD)of the CR time series as measured by neutron monitors(NMs)and by muon detectors has a rather complicated character.Along with the shape(slope)of the PSD,knowledge of the contribution of quasi-periodic variations(q-per)to the CR signal is of importance for the modulation,as well as for checking the links of CR to space weather,and/or to space climate effects.The rotation of the Earth and solar rotation cause two types of mechanisms behind the certain q-per observed in secondary CR on the Earth’s surface.Solar activity and solar magnetic field cyclicities contribute to the q-per signals in CR if studied over a longer time.The complexity of the spatial structure of the interplanetary magnetic field(IMF)and its evolution within the heliosphere,in addition to the changes in the geomagnetic field,cause variability in contributions of the q-per in CR.Wavelet spectra are useful tools for checking the fine structure of q-per and their temporal behaviour.Over a long time NMs and muon telescopes provide information about q-per in CR.