Differential Action of Glycoprotein Hormones: Significance in Cancer Progression

Growth of multicellular organisms depends on maintenance of proper balance between proliferation and differentiation. Any disturbance in this balance in animal cells can lead to cancer. Experimental evidence is provided to conclude with special reference to the action of follicle-stimulating hormone (FSH) on Sertoli cells, and luteinizing hormone (LH) on Leydig cells that these hormones exert a differential action on their target cells, i.e., stimulate proliferation when the cells are in an undifferentiated state which is the situation with cancer cells and promote only functional parameters when the cell are fully differentiated. Hormones and growth factors play a key role in cell proliferation, differentiation, and apoptosis. There is a growing body of evidence that various tumors express some hormones at high levels as well as their cognate receptors indicating the possibility of a role in progression of cancer. Hormones such as LH, FSH, and thyroid-stimulating hormone have been reported to stimulate cell proliferation and act as tumor promoter in a variety of hormone-dependent cancers including gonads, lung, thyroid, uterus, breast, prostate, etc. This review summarizes evidence to conclude that these hormones are produced by some cancer tissues to promote their own growth. Also an attempt is made to explain the significance of the differential action of hormones in progression of cancer with special reference to prostate cancer.

Action of Hopf on the twisted modular Hecke operator

Let Gamma subset of SL2(Z) be a principal congruence subgroup. For each sigma is an element of SL2(Z), we introduce the collection A(sigma)(Gamma) of modular Hecke operators twisted by sigma. Then, A(sigma)(Gamma) is a right A(Gamma)-module, where A(Gamma) is the modular Hecke algebra introduced by Connes and Moscovici. Using the action of a Hopf algebra h(0) on A(sigma)(Gamma), we define reduced Rankin-Cohen brackets on A(sigma)(Gamma). Moreover A(sigma)(Gamma) carries an action of H 1, where H 1 is the Hopf algebra of foliations of codimension 1. Finally, we consider operators between the levels A(sigma)(Gamma), sigma is an element of SL2(Z). We show that the action of these operators can be expressed in terms of a Hopf algebra h(Z).

Effective Stress and Liquefaction of Seabed Under the Action of Standing Waves

波浪作用下海床的稳定性与液化分析是海底管线、防波堤和海洋平台设计中必须仔细考虑的问题。推荐了一个循环载荷作用下土体的弹塑性实用本构模型,并给出了一种粉土的模型参数,该模型直接根据初始应力状态和循环应力的大小与作用时间计算土体的塑性应变增量,在有限元计算中不需要引入弹塑性矩阵。采用Biot理论和有限单元法,对海床有效应力的变化过程分析表明,波腹点下海床存在较大的液化可能性。波浪作用对海床存在一定的压密作用。

Molecular mechanisms of interleukin-2 gene inducibility: developmental control and combinatorial action of transcription factors

Interleukin-2 is one of the lymphokines secreted by T helper type 1 cells upon activation mediated by T-cell receptor (TCR) and accessory molecules. The ability to express IL-2 is correlated with T-lineage commitment and is regulated during T cell development and differentiation. Understanding the molecular mechanism of how IL-2 gene inducibility is controlled at each transition and each differentiation process of T-cell development is to understand one aspect of T-cell development. In the present study, we first attempted to elucidate the molecular basis for the developmental changes of IL-2 gene inducibility. We showed that IL-2 gene inducibility is acquired early in immature CD4- CD8-TCR- thymocytes prior to TCR gene rearrangement. Similar to mature T cells, a complete set of transcription factors can be induced at this early stage to activate IL-2 gene expression. The progression of these cells to cortical CD4^+CD8^+TCR^(1o) cells is accompanied by the loss of IL-2 gene inducibility. We demonstrated that DNA binding activities of two transcription factors AP-1 and NF-AT are reduced in cells at this stage. Further, the loss of factor binding, especially AP-1, is attributable to the reduced ability to activate expression of three potential components of AP-1 and NF-AT, including c-Fos, FosB, and Fra-2. We next examined the interaction of transcription factors and the IL-2 promoter in vivo by using the EL4 T cell line and two non-T cell lines. We showed an all-or-none phenomenon regarding the factor-DNA interaction, i.e., in activated T cells, the IL-2 promoter is occupied by sequence-specific transcription factors when all the transcription factors are available; in resting T cells or non-T cells, no specific protein-DNA interaction is observed when only a subset of factors are present in the nuclei. Purposefully reducing a particular set of factor binding activities in stimulated T cells using pharmacological agents cyclosporin A or forskolin also abolished all interactions. The results suggest that a combinatorial and coordinated protein-DNA interaction is required for IL-2 gene activation. The thymocyte experiments clearly illustrated that multiple transcription factors are regulated during intrathymic T-cell development, and this regulation in tum controls the inducibility of the lineage-specific IL-2 gene. The in vivo study of protein-DNA interaction stressed the combinatorial action of transcription factors to stably occupy the IL-2 promoter and to initiate its transcription, and provided a molecular mechanism for changes in IL-2 gene inducibility in T cells undergoing integration of multiple environmental signals.

Action of ecdysterone on the moulting of amphipod females: Gammarus pulex (L.) and G.fossarum Koch. Early results. [Translation from: Crustaceana 28, 86-88, 1975.]

In studying sexual attraction in gammarids of the group pulex, it has seemed necessary to dissociate the processes of moulting and ovogenesis in order to recognize their respective effects on this phenomenon. For this purpose a synthetic hormone, ecdysterone, was utilized. In the first instance the author followed the action of the hormone on isolated females in vitellogenesis. It was proved that the behaviour of Gammarus pulex and Gammarus fossarum vis-a-vis the ecdysterone used proves to be very close to that of isopods that was observed in Orchestia gammarellus in earlier research. Although they were in vitellogenesis, the females saw their intermoult cycle shortened.

Influence of nutrient source on specific dynamic action of Pearl Spot, Etroplus suratensis (Bloch)

The magnitude of apparent specific dynamic action (SDA), the maximum rate of oxygen consumption and the length of time that the rate of oxygen uptake remained elevated above the prefeeding level were measured in the Pearl Spot, Etroplus suratensis, fed isonitrous test diets (D 1 - D 4 ) with varying nutrient sources. Irrespective of the diets, the metabolic rate increased immediately after feeding and reached the maximum within 3 to 4 hours. The source of nutrients in the diet significantly altered the magnitude of SDA. It was maximum (91.76% and 129.56%) for those fed on diets D 2 and D 3 and minimum 46.47% and 50.30% for those fed on diets D 1 and D 4 , respectively.