Marrow mesenchymal stem cells transduced with TPO/FL genes as support for ex vivo expansion of hematopoietic stem/progenitor cells

A new marrow-derived mesenchymal stem cell (hMSC) line that could support expansion of hematopoietic stem/progenitor cells (HSPCs) was developed. Primary hMSCs were infected with retrovirus containing Flt-3 ligand and thrombopoietin genes. CD34+ cells from cord blood were expanded with primary hMSCs or transduced hMSCs. The expansion of total nucleated cells, CD34+ cells and mixed colonies containing erythroid and myeloid cells and megakaryocytes for 2 weeks coculture with transduced hMSCs was remarkably increased. The outputs of long-term culture-initiating cells for 2 and 4 weeks coculture with transduced hMSCs were also largely increased. The expansion rates of HSPCs with transduced hMSCs were unchanged for 6 weeks. In contrast, the expansion rates of HSPCs with primary hMSCs declined drastically through 6 weeks. SCID-repopulating cell expansion with transduced hMSCs for 4 weeks was significantly higher than that of uncultured CD34+ cells and HSPCs expanded with primary hMSCs. Received 21 June 2005; received after revision 30 July 2005; accepted 24 August 2005     

Copper and zinc dismetabolism in the mouse brain upon chronic cuprizone treatment

Recent reports describe successful treatment using copper chelation therapy in neurodegenerative animal models. However, the success claimed for chelation therapy in neurodegenerative diseases is still rather controversial. To acquire new information on copper metabolism/homeostasis, we utilized cuprizone, a very sensitive and selective copper-chelating agent with well-known neurotoxic properties, as a relevant chemical model in mice. Upon cuprizone treatment, mice developed a pronounced astrocytosis, with brain oedema and spongiosis characterised by vacuolisations of the neuropil predominantly in the white matter. In addition, cuprizone treatment severely altered copper and zinc homeostasis in the central nervous system (CNS) as well as in all other tissues examined, with increasing metal ion concentrations particularly in the CNS. Concomitant with this increase in the Cu and Zn concentration in the brain, metallothionein-I and -II were also highly immunoreactive in astrocyte, consistent with the astrocytosis and demyelination observed in our and other laboratories.Received 23 February 2005; received after revision 3 May 2005; accepted 13 May 2005     

The PREPL A protein, a new member of the prolyl oligopeptidase family, lacking catalytic activity

The PREPL (previously called KIAA0436) gene encodes a putative serine peptidase from the prolyl oligopeptidase family. A chromosomal deletion involving the PREPL gene leads to a severe syndrome with multiple symptoms. Homology with oligopeptidase B suggested that the enzyme cleaves after an arginine or lysine residue. Several PREPL splice variants have been identified, and a 638-residue variant (PREPL A) was expressed in Escherichia coli and purified. Its secondary structure was similar to that of oligopeptidase B, but differential-scanning calorimetry indicated a higher conformational stability. Dimerization may account for the enhanced stability. Unexpectedly, the PREPL A protein did not cleave peptide substrates containing a P1 basic residue, but did slowly hydrolyse an activated ester substrate, and reacted with diisopropyl fluorophosphate. These results indicated that the catalytic serine is a reactive residue. However, the negligible hydrolytic activity suggests that the function of PREPL A is different from that of the other members of the prolyl oligopeptidase family.     

Compensatory caspase activation in MPP+-induced cell death in dopaminergic neurons

Many have hypothesized that cell death in Parkinsons disease is via apoptosis and, specifically, by the mitochondrial-mediated apoptotic pathway. We tested this hypothesis using a mouse dopaminergic cell line of mesencephalic origin, MN9D, challenged with the Parkinsonism-causing neurotoxin MPP⁺ (1-methyl-4-phenylpyridinium ion). Apoptosis was the main mode of cell death when the cells were subjected to MPP⁺ treatment under serum-free conditions for 24 h. Caspase-3 and caspase-9, however, were not activated, thus indicating the existence of alternate or compensatory cell death pathway(s) in dopaminergic neuronal cells. Using caspase inhibitors, we demonstrated that these pathways involve caspase-2, –8, –6 and –7. A time-course study indicated that activation of caspase-2 and –8 occurred upstream of caspase-6 and caspase-7. Upon MPP⁺ challenge, the apoptosis-inducing factor was translocated from the mitochondria into the MN9D cytosol and nucleus. These results suggest the existence of alternative apoptotic pathways in dopaminergic neurons.Received 20 September 2004; received after revision 5 November 2004; accepted 22 November 2004     

浅议新世纪网络信息服务

论述了新世纪网络环境信息服务的特点及网络信息服务的发展方向,探讨了利用网络信息资源开拓信息服务的方法。     

柴达木盆地本地资源盐生植物的应用及引种外源盐生植物的评估

本文对柴达木盆地的盐生植物进行了梳理、评价,以期确定可用于盆地内多类盐土地的生物治理改良,且有较大经济价值而可持续发展的本地盐生植物,并依据这些植物的生理生态特性及其生长环境来选择一些适合引种的外源的经济盐生植物候选物种.     

乘积空间中一新型的不动点

本文给出了乘积空间中一新型的不动点定理,推广了一些相关的已知结果。