Cyclosporins: Immunosuppressive agents with antitumor activity

Summary Initial screening of the 2 recently developed immunosuppressive agents, cyclosporin A and cyclosporin C, in 11 murine transplantable neoplasms revealed significant increase of lifespan with long-term survivors after i.p. injection to the ascites tumors, Taper liver, Sarcoma 180J and Ehrlich.This work was supported in part by grant CA-08748 from the National Cancer Institute, National Institutes of HealthDepartment of Health, Education and Welfare. The authors are indebted to Drs Dorris J. Hutchison, M.N. Teller and H. Stähelin for helpful discussions, and to Dr A. von Wartburg of Sandoz AG, Basel, for the supply of the cyclosporins.     

Prostaglandin analogue protects pancreatic B-cells against cyclosporin A toxicity

Cyclosporin A toxicity on pancreatic B-cells and its prevention by rioprostil, a prostaglandin E1 analogue, were studied in the model of the isolated perfused pancreas of rats treated with both compounds for 8 days. At toxic doses of cyclosporin (10 and 20 mg/kg b.wt), the B-cells showed severe hydropic degeneration of the endoplasmatic reticulum and slight degranulation of the B-cells. Accordingly, the insulin secretion was markedly impaired. Administration of rioprostil ameliorated the insulin secretion significantly, but not the ultrastructural changes. At therapeutic levels of cyclosporin (5 mg/kg b.wt), the hydropic degeneration and the drop in insulin secretion were completely prevented by rioprostil. This observation might have therapeutic implications in the treatment of patients, in particular those undergoing pancreatic transplantation.     

Prostaglandin analogue protects pancreatic B-cells against cyclosporin A toxicity

Summary Cyclosporin A toxicity on pancreatic B-cells and its prevention by rioprostil, a prostaglandin E₁ analogue, were studied in the model of the isolated perfused pancreas of rats treated with both compounds for 8 days. At toxic doses of cyclosporin (10 and 20 mg/kg b.wt), the B-cells showed severe hydropic degeneration of the endoplasmatic reticulum and slight degranulation of the B-cells. Accordingly, the insulin secretion was markedly impaired. Administration of rioprostil ameliorated the insulin secretion significantly, but not the ultrastructural changes. At therapeutic levels of cyclosporin (5 mg/kg b.wt), the hydropic degeneration and the drop in insulin secretion were completely prevented by rioprostil. This observation might have therapeutic implications in the treatment of patients, in particular those undergoing pancreatic transplantation.     

Development of high blood pressure in spontaneously hypertensive rats is delayed by treatment with cyclosporin at an early age

In spontaneously hypertensive rats the effect of the T-cell inhibitor cyclosporin was studied at different ages. If treatment was started at the age of 2 weeks the development of hypertension was delayed, but the ultimate level of blood pressure was not affected. These results indicate the involvement of immune mechanisms in the early development of hypertension in spontaneously hypertensive rats.     

Development of high blood pressure in spontaneously hypertensive rats is delayed by treatment with cyclosporin at an early age

Summary In spontaneously hypertensive rats the effect of the T-cell inhibitor cyclosporin was studied at different ages. If treatment was started at the age of 2 weeks the development of hypertension was delayed, but the ultimate level of blood pressure was not affected. These results indicate the involvement of immune mechanisms in the early development of hypertension in spontaneously hypertensive rats.     

The history of cyclosporin A (Sandimmune®) revisited: Another point of view

The immunosuppressant cyclosporin A (Sandimmune^®) has become the first line treatment for preventing rejection of transplanted organs and for certain, autoimmune diseases. The discovery of that drug and its preclinical development are described, and it is shown that most earlier accounts of the history of this compound are, in important respects, incorrect and misleading.     

Contribution to knowledge of the biosynthesis of cyclosporin A

3H- and 13C-NMR spectroscopic investigations on the structure of labeled cyclosporin A were performed after feeding of appropriate precursors. The 6 N-methyl groups and the methyl group in position 4 of the epsilon, zeta-unsaturated amino acid No. 1 (Mebmt) are introduced as intact CH3-units from methionine. Four head-to-tail acetate units are involved in the biosynthesis of the 8-carbon chain of the olefinic amino acid.     

FK506 sensitizes mammalian cells to high osmolarity by modulating p38 MAP kinase activation

The immunosuppressants tacrolimus (FK506) and cyclosporin A (CsA) have increased the survival rates in organ transplantation. Both drugs inhibit the protein phosphatase calcineurin (CaN) in activated T cells, exhibiting similar side-effects. Diabetes is observed more often in FK506 than CsA therapy, probably due to inhibition of new molecular targets other than CaN. We studied FK506 toxicity in mammalian cells. FK506, but not CsA, regulated p38 activation by osmotic stress, and decreased viability in osmostressed cells. In addition, FK506 treatment strongly increased the phosphorylation of the eukaryotic initiation factor-2a (eIF-2a) subunit. eIF-2a phosphorylation, p38 inhibition and cell lethality were relieved by addition of excess amino acids to the medium, suggesting that amino acid availability mediated FK506 toxicity. Therefore, these FK506-dependent responses could be relevant to the non-therapeutic effects of FK506 therapy.Received 16 October 2003; received after revision 8 January 2004; accepted 14 January 2004     

Dual antiglioma action of metformin: cell cycle arrest and mitochondria-dependent apoptosis

The present study reports for the first time a dual antiglioma effect of the well-known antidiabetic drug metformin. In low-density cultures of the C6 rat glioma cell line, metformin blocked the cell cycle progression in G₀/G₁ phase without inducing significant cell death. In confluent C6 cultures, on the other hand, metformin caused massive induction of caspase-dependent apoptosis associated with c-Jun N-terminal kinase (JNK) activation, mitochondrial depolarization and oxidative stress. Metformin-triggered apoptosis was completely prevented by agents that block mitochondrial permeability transition (cyclosporin A) and oxygen radical production (N-acetylcisteine), while the inhibitors of JNK activation (SP600125) or glycolysis (sodium fluoride, iodoacetate) provided partial protection. The antiglioma effect of metformin was reduced by compound C, an inhibitor of AMP-activated protein kinase (AMPK), and was mimicked by the AMPK agonist AICAR. Similar effects were observed in the human glioma cell line U251, while rat primary astrocytes were completely resistant to the antiproliferative and proapoptotic action of metformin. Received 14 February 2007; received after revision 26 March 2007; accepted 3 April 2007     

Multiple roles of the DSCR1 (Adapt78 or RCAN1) gene and its protein product Calcipressin 1 (or RCAN1) in disease

The DSCR1 (Adapt78) gene¹ is transiently induced by stresses to temporarily protect cells against further potentially lethal challenges. However, chronic expression of the DSCR1 (Adapt78) gene has now been implicated in several pathological conditions including Alzheimer’s disease, Down syndrome and cardiac hypertrophy. Calcipressin 1 has been shown to function through direct binding and inhibition of the serine threonine protein phosphatase Calcineurin. Pharmacological inhibition of calcineurin, by the immunosuppressive drugs cyclosporin A and FK506, affects a wide variety of diseases. It is, therefore, likely that this endogenous calcineurin inhibitor, calcipressin 1, may also play a role in a variety of human diseases. ¹Please note that the mammalian DSCR1 gene is also called Adapt78 or RCAN1, and its protein products have been named Calcipressin1, MCIP1 and RCAN1. A proposal to adopt a single gene name of RCAN1 and a protein name RCAN1 (for Regulator of Calcineurin) has been endorsed by the HUGO Gene Nomenclature Committee, but final approval must await agreement from a majority of researchers in the field. Received 2 March 2005; received after revision 27 May 2005; accepted 19 July 2005     

RTA2 is involved in calcineurin-mediated azole resistance and sphingoid long-chain base release in Candida albicans

The calcineurin pathway has been reported to be essential for the development of azole resistance in Candida albicans. The depletion or ectopic over-expression of RTA2 increased or decreased susceptibility of C. albicans to azoles, respectively. CaCl₂- induced activation of the calcineurin pathway in wildtype C. albicans promoted resistance to azoles, while the Ca ²⁺ chelator (EGTA), calcineurin inhibitors (FK506 and cyclosporin A) and the deletion of RTA2 blocked the resistance-promoting effects of CaCl₂. Furthermore, we found that RTA2 was up-regulated in a calcineurin-dependent manner. The depletion of RTA2 also made the cell membrane of C. albicans liable to be destroyed by azoles and RTA2 over-expression attenuated the destroying effects. Finally, the disruption of RTA2 caused an increased accumulation of dihydrosphingosine (DHS), one of the two sphingolipid long-chain bases, by decreasing release of DHS. In conclusion, our findings suggest that RTA2 is involved in calcineurin-mediated azole resistance and sphingoid long-chain base release in C. albicans. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 14 July 2008; received after revision 29 August 2008; accepted 16 September 2008     

Dexamethasone enhances CTLA-4 expression during T cell activation

T cell activation is enhanced by the costimulatory interaction of B7 on antigen-presenting cells and CD28 on T cells, resulting in long-term T cell proliferation, differentiation and production of large amounts of cytokines, such as interleukin (IL)-2. CTLA-4 is a co-stimulation receptor that shares 31% homology with CD28 and binds B7 family members with higher affinity. CTLA-4 is transiently expressed intracellularly and on the cell surface following activation of T cells. We have studied the kinetics of CTLA-4 expression and the effects of dexamethasone on CTLA-4 expression during T cell activation in cultures of mouse spleen cells stimulated by a mixture of immobilized anti-CD3 and anti-CD28 monoclonal antibodies (anti-CD3/CD28 mAb) or concanavalin A (ConA). CTLA-4 expression peaked on day 2 and returned to background levels after 7 days. Dexamethasone was found to potentiate CTLA-4 expression in a dose-dependent manner with an EC₅₀ effective concentration 50%) of about 10⁻⁸ M. In contrast, other immunosuppressive agents, such as rapamycin or cyclosporin A had no or an inhibitory effect on CTLA-4 expression, respectively. Dexamethasone also stimulated CD28 expression, but inhibited IL-2R expression during anti-CD3/CD28 mAb-induced mouse splenic T cell activation. Western blot analyses of lysates of activated mouse T cells showed that dexamethasone increased CTLA-4 protein levels twofold during anti-CD3/CD28 mAb-induced activation. Dexamethasone also enhanced CTLA-4 messenger RNA twofold as quantified by ribonuclease protection assay. The effects of dexamethasone on CTLA-4 expression were glucocorticoid-specific and completely inhibited by the glucocorticoid receptor antagonist mifepristone (RU486), indicating that the effect of dexamethasone on CTLA-4 expression is mediated through the glucocorticoid receptor. In conclusion, the immunosuppressive agent dexamethasone actually stimulates CTLA-4 expression, which is involved in downregulation of T cell activation. Received 19 May 1999; received after revision 13 July 1999; accepted 13 July 1999     

Peptidyl-prolyl cis-trans isomerases, a superfamily of ubiquitous folding catalysts

Cyclosporine A therapy for prophylaxis against graft rejection revolutionized human organ transplantation. The immunosuppressant drugs cyclosporin A (CsA), FK506 and rapamycin block T-cell activation by interfering with the signal transduction pathway. The target proteins for CsA and FK506 were found to be cyclophilins and FK506-binding proteins, (FKBPs), respectively. They are unrelated in primary sequence, although both are peptidyl-prolyl cis-trans isomerases catalyzing the interconversion of peptidyl-prolyl imide bonds in peptide and protein substrates. However, the prolyl isomerase activity of these proteins is not essential for their immunosuppressive effects. Instead, the specific surfaces of the cyclophilin-CsA and FKBP-FK506 complexes mediate the immunosuppressive action. Moreover, the natural cellular functions of all but a few remain elusive. In some cases it could be demonstrated that prolyl isomerization is the rate-limiting step in protein folding in vitro, but many knockout mutants of single and multiple prolyl isomerases were viable with no detectable phenotype. Even though a direct requirement for in vivo protein folding could not be demonstrated, some important natural substrates of the prolyl isomerases are now known, and they demonstrate the great variety of prolyl isomerization functions in the living cell: (i) A human cyclophilin binds to the Gag polyprotein of the human immunodeficiency virus-1 (HIV-1) virion and was found to be essential for infection with HIV to occur, probably by removal of the virion coat. (ii) Together with heat shock protein (HSP) 90, a member of the chaperone family, high molecular weight cyclophilins and FKBPs bind and activate steroid receptors. This example also demonstrates that prolyl isomerases act together with other folding enzymes, for example the chaperones, and protein disulfide isomerases. (iii) An FKBP was found to act as a modulator of an intracellular calcium release channel. (iv) Along with the cyclophilins and FKBPs, a third class of prolyl isomerases exist, the parvulins. The human parvulin homologue Pin1 is a mitotic regulator essential for the G2/M transition of the eukaryotic cell cycle. These findings place proline isomerases at the intersection of protein folding, signal transduction, trafficking, assembly and cell cycle regulation. Received 18 September 1998; received after revision 4 November 1998; accepted 23 November 1998     

亚高山针叶林群落系统的生态学过程和持续性机制

森林生态系统由于其复杂的物质循环与能量转化通道，直接参与地图一生物圈问的生物地球化学循环。因此，对森林生态系统结构与功能的研究一直是研究全球生态环境问题的核心。目前在这个研究领域的共识是：对生态系统功能的了解首先是基于对系统组分过程结构和动态的理解，而生态系统多功能的持续性机制在于确保组成系统的各组分过程结构的维持和良好的协调。在森林群落生态系统中，最基本的植物、生态学过程是能流传输(transfer)和分配(partitioning)过程，碳、养分和水循环过程，生态位的相对稳定和分化过程以及植物的生长，死亡和更新过程。川西亚高山针叶林是我国西部目前唯一保存良好的天然森林。除了它重要的、不可替代的生态、经济和社会地位外，从生态系统本身以及与全球气候变化的联系上，地处高寒环境下的川西亚高山针叶林生态系统有其独特之处：相对简单的层次结构和种丰富度，清晰的更新和演替规律，有意义的地质、气候和区系历史，巨大的土壤冷冻碳库，更加分化的结构和功能类型，复杂的地形、地貌组合以及生态位的多样性等。这些特征一方面给系统生态过程研究带来许多挑战性的问题，另一方面为研究植被动态过程以及植被与气候变化相互作用提供了一个天然实验室。     

Melatonin,clock genes and mitochondria in sepsis

After the characterization of the central pacemaker in the suprachiasmatic nucleus, the expression of clock genes was identified in several peripheral tissues including the immune system. The hierarchical control from the central clock to peripheral clocks extends to other functions including endocrine, metabolic, immune, and mitochondrial responses. Increasing evidence links the disruption of the clock genes expression with multiple diseases and aging. Chronodisruption is associated with alterations of the immune system, immunosenescence, impairment of energy metabolism, and reduction of pineal and extrapineal melatonin production. Regarding sepsis, a condition coursing with an exaggerated response of innate immunity, experimental and clinical data showed an alteration of circadian rhythms that reflects the loss of the normal oscillation of the clock. Moreover, recent data point to that some mediators of the immune system affects the normal function of the clock. Under specific conditions, this control disappears reactivating the immune response. So, it seems that clock gene disruption favors the innate immune response, which in turn induces the expression of proinflammatory mediators, causing a further alteration of the clock. Here, the clock control of the mitochondrial function turns off, leading to a bioenergetic decay and formation of reactive oxygen species that, in turn, activate the inflammasome. This arm of the innate immunity is responsible for the huge increase of interleukin-1β and entrance into a vicious cycle that could lead to the death of the patient. The broken clock is recovered by melatonin administration, that is accompanied by the normalization of the innate immunity and mitochondrial homeostasis. Thus, this review emphasizes the connection between clock genes, innate immunity and mitochondria in health and sepsis, and the role of melatonin to maintain clock homeostasis.     

高校产学研一体化发展的实践与前瞻

本文探讨我国高校产学研一体化发展的必要性、可行性及其前景。从人类社会发展的历史特点入手，并借鉴了美国硅谷发展的经验和我国改革开放推进社会主义市场发展的需求，对高校产学研一体化发展的道路作了论述。针对目前高校产学研一体化中存在的问题，作者提出了加速高校产学研一体化发展的四条建议：1，高校产学研一体化发展必须转变观念，积极参与社会大循环；2，推进高校产学研一体化要有过硬的产品和准确的市场定位；3，高校产学研一体化发展要依托高科技园区，切实解决经费投入问题；4，高校产学研一体化发展要突出以人为本的思想，努力造就发明家和企业家。     

新西兰政府科技投资现状概述

近年来新西兰政府大力调整其科技政策，在建设知识社会的蓝图下，建构了科技投资的基本框架，凸显了知识、经济、环境、社会四大目标，另外通过对投资决策、运行和监督的改革，使政府科技投资的机制更为科学有效，本文还给出了新西兰政府近年来科技投资的分配比例状况，阐明了其投资的重点领域。