平衡分布与寿命分布类

平衡分布给出了L分布类一个新的定义方式,并证明新定义与原定义等价.研究了平衡分布的一些性质,通过寿命的平衡分布与指数分布在Laplace变换下的比较,得到一种判定L(-L)类寿命分布的方法.进一步用平衡变量Xe的期望与寿命X的期望作比较提出一种新的寿命分布类--E类,研究了E类与其他寿命分布类之间的蕴含关系,证明了E类是比L类更大的一个分布类.最后讨论了E类在卷积下的封闭性质.     

Identification of a new class of steroid hormone receptors

The gonads and adrenal glands produce steroids classified into five major groups which include the oestrogens, progestins, androgens, glucocorticoids and mineralocorticoids. Gonadal steroids control the differentiation and growth of the reproductive system, induce and maintain sexual characteristics and modulate reproductive behaviour. Adrenal steroids also influence differentiation as well as being metabolic regulators. The effects of each steroid depend primarily on its specific receptors, the nature of which could therefore provide a basis for classification of steroid hormone action. The successful cloning, sequencing and expression of the human glucocorticoid (hGR) (ref. 1), oestrogen (hER), progesterone (hPR), and mineralocorticoid (hMR) receptors, complementary DNA, plus homologues from various species, provides the first opportunity to study receptor structure and its influence on gene expression. Sequence comparison and mutational analysis show structural features common to all groups of steroid hormone receptors. The receptors share a highly conserved cysteine-rich region which functions as the DNA-binding domain. This common segment allows the genome to be scanned for related gene products: hMR cDNA for example, was isolated using an hGR hybridization probe. In this study, using the DNA-binding domain of the human oestrogen receptor cDNA as a hybridization probe, we have isolated two cDNA clones encoding polypeptides with structural features suggestive of cryptic steroid hormone receptors which could participate in a new hormone response system.     

考虑索赔额的NCD系统平稳分布研究

由于现行的NCD系统仅考虑索赔次数而没有考虑索赔额度,因而存在着很大的局限性.建立考虑索赔额度的一类NCD系统.该类NCD系统是基于索赔额函数而建立的,并且存在唯一的平稳分布.此外,还给出了求解这一平稳分布的方法,并给出了一个实例.     

基于产品替代度的分销系统的均衡分析

产品替代度是研究分销渠道中生产商层次竞争的关键因素,以前大量的研究都假设2个生产商之间产品的替代度相同,实际上,替代度不同更符合现实情况;基于这样的假设,该文探讨了产品替代度、不同的渠道权力结构对参与各方均衡结果的影响作用,并与以前的替代度相同模型进行了比较、讨论;最后给出一个算例以说明本模型。     

Agonist-independent activation of metabotropic glutamate receptors by the intracellular protein Homer.

G-protein-coupled receptors (GPCRs) transduce signals from extracellular transmitters to the inside of the cell by activating G proteins. Mutation and overexpression of these receptors have revealed that they can reach their active state even in the absence of agonist, as a result of a natural shift in the equilibrium between their inactive and active conformations. Such agonist-independent (constitutive) activity has been observed for the glutamate GPCRs (the metabotropic glutamate receptors mGluR1a and mGluR5) when they are overexpressed in heterologous cells. Here we show that in neurons, the constitutive activity of these receptors is controlled by Homer proteins, which bind directly to the receptors' carboxy-terminal intracellular domains. Disruption of this interaction by mutagenesis or antisense strategies, or expression of endogenous Homer1a (H1a), induces constitutive activity in mGluR1a or mGluR5. Our results show that these glutamate GPCRs can be directly activated by intracellular proteins as well as by agonists.     

Effect of serum on PEGylated quantum dots: Cellular uptake and intracellular distribution

Protein adsorption is closely related with the interactions between nanoparticles and physiological systems,and further influences the cellular uptake and distribution of nanoparticles in cells.Although polyethylene glycol(PEG)ylation can largely reduce specific protein adsorption,some protein components in whole serum still interact with nanoparticles.In this work,PEGylated quantum dots(QDs) were used for investigating the quantitative and qualitative relationships of fetal bovine serum(FBS) and the cellular uptake/intracellular distribution in human hepatoma(HepG2) cell line.Nondenaturing polyacrylamide gel electrophoresis and two dimensional electrophoresis were used to analyze the adsorption of protein by PEGylated QDs.Quantitative cellular uptake of PEGylated QDs was determined by fluorescence activated cell sorting(FACS) with different FBS concentrations and incubating durations.The intracellular location of PEGylated QDs in HepG2 cells was observed using a confocal laser scanning microscope(CLSM) and a transmission electron microscope(TEM).This work will be helpful to understand the interaction between nanoparticles and cells with serum.     

Common non-hormone binding component in non-transformed chick oviduct receptors of four steroid hormones

Steroid hormones produce a response in target cells by binding to hormone-specific soluble receptors, which undergo a transformational change, leading to their interaction with chromatin and to modified gene expression. In a previous paper, we described a monoclonal antibody, BF4, that specifically recognizes and binds the non-transformed '8S' form of chicken oviduct progesterone receptor (8S-PR). We now show that BF4 does not form an immune complex with the 4S transformed form of 3H-progestin-labelled progesterone receptor, but does interact with the 8S non-transformed forms of the oestrogen, androgen and glucocorticosteroid receptors. Our results suggest that the antigenic determinant recognized by BF4 is present on a non-hormone binding unit, which we identify as a polypeptide of molecular weight (MW) 90,000 in the case of the progesterone receptor, and that this unit is common to other 8S non-transformed chicken steroid receptors.     

商业银行业中的垄断均衡和竞争均衡

本文分析3种银行放贷均衡。对企业有完全信息的垄断银行,银行收益和企业努力程度与抵押物无关,但抵押物有助于降低利率;对企业无完全信息的垄断银行,银行收益也与抵押物无关,抵押物也有助于降低利率,但企业努力程度与抵押物有关;对企业拥有完全信息的银行以及有不完全信息但相互之间是竞争的银行,有完全信息的银行由于拥有信息优势,获得较高的利润。     

球对称恒星的引力平衡与平衡态附近的振荡

根据球对称恒星引力与压力间的平衡,用半定量方法得到了恒星振动周期与其平均密度的关系。简要地说明了周光关系方法测量恒星距离的原理。     

Autoradiographic distribution of substance P receptors in rat central nervous system

Among various neuropeptides present in the central nervous system (CNS), substance P, an undecapeptide, is of great interest as a putative pain neurotransmitter. Substance P is present within numerous intrinsic neural pathways throughout the CNS. Several groups have attempted to label substance P receptors on brain membranes by ligand binding techniques; only one study used native 3H-labelled substance P as the ligand and the precise anatomical distribution of substance P receptors has not yet been described. Here we report the autoradiographic localization of 3H-labelled substance P receptors in rat brain using the in vitro autoradiographic technique developed recently. 3H-substance P binds specifically to an apparently single class of sites on slide-mounted brain sections (Kd = 0.52 nM; Bmax = 21.6 fmol per mg protein). The ligand selectivity pattern suggests that 3H-substance P binding sites are similar to those found in other assays. 3H-substance P receptors are highly concentrated in the external layers of the olfactory bulb, medial amygdala, dentate gyrus, superior colliculus, dorsal parabrachial nucleus and locus coeruleus, with moderate densities being found in the nucleus accumbens, striatum, periaqueductal grey and subiculum. The distribution of 3H-substance P receptors suggests that substance P is probably involved in the control of sensory processes such as pain, vision, audition and olfaction.