Development of specific suppressor cells in hypoinsulinaemic mice

Mice and rats injected with alloxan or streptozotocin develop permanent diabetes, characterised by deficient insulin production. It has been demonstrated that hypoinsulinaemia in mice leads to significant loss of lymphatic tissue, and these diabetic animals cannot develop contact sensitivity or efficient graft rejection. Administration of insulin partially restored these responses and also caused an increase in the weight of the thymus and spleen. Similar suppression of T cell-dependent phenomena has been observed in surgically pancreatectomised rats. Lymphocytes of these hypoinsulinaemic animals show significantly decreased in vitro responses to plant lectins and generate only low levels of cytotoxic effector cells. We previously showed that cells of normoglycaemic oxazolone-sensitised mice cannot transfer significant contact sensitivity reactions into diabetic recipients indicating that the milieu of hyperglycaemic insulin deficient animals cannot support all the activity of immune T cells. By mixing immunised T cells from control and diabetic mice and transferring the mixtures into normal recipients we now show that the non-supportive millieu in diabetic animals may be due to active suppression rather than to athrepsis.     

Isolation of a replication-defective murine leukaemia virus from cultured AKR leukaemia cells.

Mice of the AKR strain are characterised by a high incidence of spontaneous thymic lymphomas. AKR chromosomes contain the genomes of ecotropic murine leukaemia virus (MuLV) at two loci, termed Akv-1 and Akv-2 (refs 2-6). Shortly after birth, the normal tissues of AKR mice begin to produce high levels of this XC-positive MuLV (ref. 7) (that is, one that forms XC plaques). A second class of MuLV, termed mink cell focus-inducing virus (MCF), is produced specifically by preleukaemic and leukaemic AKR thymocytes. Nowinski et al. have established a series of tissue culture lines from AKR leukaemias and reported that the resulting cell lines produce virus particles, but that these particles, surprisingly, do not give rise to XC plaques. We have analysed the virus particles produced by one of these cell lines, termed AKRSL2. We show here that, unlike most or all of the nonmalignant tissues in the AKR mouse, these cultured lymphoma cells produce very little non-defective ecotropic MuLV; however, they do produce replication-defective ecotropic MuLV.     

Surface antibodies of human myelogenous leukaemia leukocytes reactive with specific type-C viral reverse transcriptases.

Purified immunoglobin G (IgG) from patients with chronic myelogenous leukaemia specifically neutralised RT from feline leukaemia virus while purified IgG from other types of leukaemias and from normal blood cells were less reactive and in some cases preferentially reacted with RT from horizontally transmitted primate type-C viruses (simian sarcoma virus-gibbon ape leukaemia virus group). This indicates the presence of a heterogeneous immune response to RT or to an RT-like molecule in humans.     

High-affinity binding site for a specific nuclear protein in the human IgM gene

Proteins binding to specific regions of DNA with high affinity frequently govern or regulate reactions at the gene level. We have identified a high-affinity binding site in the immunoglobulin mu gene that binds a specific nuclear protein, and have now characterized it fully using nuclear factor 1 (NF-1), a protein purified from the nuclei of HeLa cells and required for the in vitro replication of adenovirus (Ad) DNA. NF-1 protects a 25-base pair (bp) double-stranded segment of DNA which shares a consensus sequence, 5' TGGA/CNNNNNGCCAA 3', with similar binding sites in the Ad-5 terminal repeat and the human c-myc gene. Although this site differs from the enhancer region, a biological function is suggested by the fact that it is DNase I hypersensitive in immunoglobulin-producing lymphoblastoid cells. The binding site for the NF-1 protein in the mu gene, by analogy with the site in the Ad-5 terminal repeat, may represent one component of a cellular origin of replication; alternatively, it may be responsible for the activation of the chromatin in this region.     

特种分离EDI过程处理模拟电镀镍漂洗水的研究

以电镀镍漂洗水为代表的低浓度重金属离子废水属于对环境危害极大的一类污染物.含有改进内部构造的特种分离电去离子(EDI)过程,是一种高效、稳定、环境友好的低浓度重金属离子废水处理新工艺.本文利用模拟电镀镍漂洗水,研究了填充树脂类型以及树脂粒径分布对该特种分离EDI过程分离效率的影响.研究表明,使用窄粒径分布的大孔强酸、强碱性混床树脂是特种分离EDI处理低浓度重金属离子废水过程传质强化的有效途径之一.