A short history of nuclear activation analysis

The major developments in the field of nuclear activation analysis, from 1936 to 1989, are discussed. The developments are grouped into five consecutive time periods. The impact of various scientists on the development of the field in the first 35 years is also discussed.     

多样性指数公式在鸟类群落中应用的探讨

一、前言多样性是反映生物群落功能的组织特征,它与生境密切相关,可以作为生态学上的一个灵敏度指标;它是群落中关于丰富度和均匀度的一个函数,用其指数可以定量地分析群落的     

水土保持耕作法是治理黄土高原地区坡耕地的根本措施

坡耕地所造成的土壤侵蚀,已成为全世界共同关注的问题。黄土高原地区,沟壑纵横,地形破碎,沟深坡陡,是世界上水土流失最强烈的地区。坡耕地的水土流失不仅是造成河流水库淤积的一个重要原因,更重要的是每年要丧失大量的肥沃表土,导致农业减产和土壤退化。一遇暴雨,人民的生命财产将遭受到巨大的威胁。黄土高原地区每年水力侵蚀土层深度达0.2—2cm,每1ha 损失表土120t 左右,损失     

正常人及肝细胞癌患者肝脏及血浆中丙酮酸激酶同工酶免疫测定

 分别从人肝及鼠肝中高度纯化L型和M_1型丙酮酸激酶(Pyk),制备相应的免抗血清。从抗血清中纯化IgG并水解成F(ab')_2,进而还原成Fab',后者与辣根过氧物酶(HRP)交联成Fab'-HRP,再利用这两种复合物建立了各自的高灵敏夹心ELISA来免疫定量L及M_2型(与鼠M_1-Pyk有交叉免疫)Pyk,结果发现:正常人肝中95％的Pyk为L型,M_2-Pyk仅占5％,而肝细胞癌中L-Pyk降至正常肝的3.5％,M_2-Pyk却增至正常的14.6倍,以致M_2-Pyk占总量的95.5％。免疫组化研究进一步证实定量的结果,正常人肝L-Pyk染色呈强阳性。M_2-Pyk染色较弱,而肝细胞癌恰好相反,L-Pyk染色明显减退,而M_2-Pyk不仅癌组织染色很深,癌周组织也明显深于正常,而且愈近癌巢,染色愈深。测定血浆Pyk,发现正常人L-Pyk占89.9％,M-Pyk(以M_2计)仅占10.1％。肝细胞癌患者血浆L-Pyk略见降低,为正常值的79.6％,p值在0.02～0.05之间,但血浆M型Pyk明显升高至正常的4.59倍,占Pyk总量的39.6％,并证明主要来源于肝癌组织中的M_2,故M_2-Pyk有可能成为肝细胞癌诊断的新指标。     

Ciliary Neurotrophic Factor (CNTF) Genotypes and CNTF Contents in Human Sciatic Nerves as Measured by a Sensitive Enzyme-Linked Immunoassay

Abstract: To study the level of ciliary neurotrophic factor (CNTF) in human nervous tissues, we developed a sensitive enzyme-linked immunoassay using a specific antibody against human CNTF. This method allowed us to detect as little as 0.3 ng/ml of human CNTF with good linearity and accuracy. Using this method, CNTF levels were determined in human sciatic nerves obtained at autopsy from 21 amyotrophic lateral sclerosis (ALS) patients and 48 subjects who had died of other neurological diseases. CNTF genotypes were also determined. The results indicated that CNTF levels were high in the normal homozygotes and approximately halved in the heterozygote subjects. There was, however, no significant difference in CNTF levels in the sciatic nerves between ALS and other neurological disease patients, indicating that the CNTF level was mainly determined by its genotypes and that the level in the sciatic nerves was not reduced in ALS patients.     

Comparison of a Bone Criterion and a dental Criterion for estimation of age at death in the study of an Ancient Cemetery

Two methods, a visual method based on the appearance of the auricular surface of the ilium and a metric method based on two dental criteria, were used in conjunction for estimation of skeletal age at death in paleodemographic study of an ancient cemetery, and were found to be coherent. However, the paleodemographic profiles differed according to sex, indicating a sexual difference in the evolution of the sacroiliac joint.     

Effect of ammonium sulfate on the phytotoxicity, foliar uptake, and translocation of imazamethabenz in wild oat

Experiments were conducted in greenhouse, growth chamber, and laboratory conditions to determine the effect of ammonium sulfate [(NH₄)₂SO₄] on the phytotoxicity, foliar uptake, and translocation of imazamethabenz on wild oat. Rates of (NH₄)₂SO₄ up to 5% (w/v) applied with a greenhouse sprayer did not affect the phytotoxicity of the herbicide when the mix was applied at the one- to two-leaf stage. However, inclusion of 1 and 2% (NH₄)₂SO₄ increased the phytotoxicity of the herbicide when the mix was sprayed at the two- to three-leaf, or the three- to four-leaf stage. At 10%, (NH₄)₂SO₄ decreased the phytotoxicity of the sublethal dosage of the herbicide. When the herbicide was applied as individual drops to the growth chamber-grown plants, inclusion of (NH₄)₂SO₄ at 1% did not affect phytotoxicity as measured by shoot growth. The presence of (NH₄)₂SO₄ did not affect the amount of imazamethabenz retained by wild oat foliage, but it decreased [¹⁴C]imazamethabenz absorption, slightly antagonized acropetal translocation, and increased the basipetal translocation of [¹⁴C]imazamethabenz. It was concluded that application methods greatly modify the effect of (NH₄)₂SO₄ on imazamethabenz phytotoxicity. Herbicide absorption and translocation as determined by one method do not necessarily represent the absorption and translocation patterns when different application methods are used. Absorption and translocation were not the factors that were responsible for the observed effect of (NH₄)₂SO₄ on the herbicide phytotoxicity.Abbreviations SC suspension concentrate     

Antiprogestagen RU486 prevents the LH-dependent decrease in the serum concentrations of inhibin in the rat

Summary 1. In the rat, the LH-dependent ovarian progesterone rise mediates several actions of the primary surge of LH on the ovary. This experiment was aimed at elucidating the effects of the antiprogestagen RU486 on the LH-dependent decrease in both the serum concentrations and the ovarian content of inhibin.2. All rats in this experiment were treated with an antagonist of LHRH (1 mg/200 µl saline at 0800 h in proestrus) to supress the endogenous release of LH. One group of rats received 32 µg LH/250 µl saline at 1200 h in proestrus. Other group was given 4 mg RU486/200 µl oil at 0800 h in proestrus. The third group was injected with both RU486 and LH. Rats from the control group were injected with 250 µl saline and 200 µl oil. Animals were decapitated at 1700 h in proestrus and trunk blood and ovaries collected to determine the serum concentrations of LH, FSH, progesterone, 17ß-estradiol and inhibin as well as the ovarian content of inhibin.3. The ovulatory dose of LH in LHRHa-treated rats decreased both the serum concentrations and the ovarian content of inhibin and increased the serum concentrations of FSH. The administration of RU486 blocked the effect of LH on the serum concentrations of inhibin but not that on the ovarian content of inhibin.4. Since the antiprogestagen RU486 blocked the effect of LH on the serum concentrations of inhibin, we conclude that ovarian progesterone, besides mediating the effects of the primary LH surge on the ovulatory process and luteinization, participates in the LH-dependent drop in the serum concentrations of inhibin in proestrous afternoon.     

Black tea,green tea,and tea polyphenols

Previous studies have shown that tea consumption can impair trace element metabolism, particularly iron status, and increase the risk of anemia in humans and animals. More recently, however, evidence has been accumulating to show that, in animals, consumption of green tea or its polyphenols is associated with a reduction of the incidence and severity of a variety of experimentally induced cancers. In this study we have monitored the growth, trace element status, including hematological parameters of weanling rats given either (1) water, (2) 1% black tea, (3) 1% green, tea, or (4) 0.2% crude green tea extract as their sole drinking fluid while consuming diets containing either adequate or low amounts of iron. With the exception of manaanese, none of the trace elements studied (iron, copper, zinc, and manganese) or the hematological indices measured were affected by the type of beverage supplied, even though the polyphenol extract was shown to chelate metals in vitro and all the animals fed the low iron diet were shown to be anemic. There appeared to be an effect of black and green teas on manganese balance in, both the first and last weeks of the study. A lower level of brain managanese was associated with green tea consumption, and a higher level of this element in the kidneys of animals fed black tea. The results demonstrate that both black and green teas and a green tea polyphenol extract do not represent a risk to animals consuming the beverages as their sole fluid intake with respect to iron availability, although the interactions with manganese deserve further study.