The cytotoxicity of eosinophil cationic protein/ribonuclease 3 on eukaryotic cell lines takes place through its aggregation on the cell membrane

Human eosinophil cationic protein (ECP)/ ribonuclease 3 (RNase 3) is a protein secreted from the secondary granules of activated eosinophils. Specific properties of ECP contribute to its cytotoxic activities associated with defense mechanisms. In this work the ECP cytotoxic activity on eukaryotic cell lines is analyzed. The ECP effects begin with its binding and aggregation to the cell surface, altering the cell membrane permeability and modifying the cell ionic equilibrium. No internalization of the protein is observed. These signals induce cell-specific morphological and biochemical changes such as chromatin condensation, reversion of membrane asymmetry, reactive oxygen species production and activation of caspase-3-like activity and, eventually, cell death. However, the ribonuclease activity component of ECP is not involved in this process as no RNA degradation is observed. In summary, the cytotoxic effect of ECP is attained through a mechanism different from that of other cytotoxic RNases and may be related with the ECP accumulation associated with the inflammatory processes, in which eosinophils are present. Received 26 October 2007; accepted 23 November 2007     

The contribution of noncatalytic phosphate-binding subsites to the mechanism of bovine pancreatic ribonuclease A

The enzymatic catalysis of polymeric substrates such as proteins, polysaccharides or nucleic acids requires precise alignment between the enzyme and the substrate regions flanking the region occupying the active site. In the case of ribonucleases, enzyme-substrate binding may be directed by electrostatic interactions between the phosphate groups of the RNA molecule and basic amino acid residues on the enzyme. Specific interactions between the nitrogenated bases and particular amino acids in the active site or adjacent positions may also take place. The substrate-binding subsites of ribonuclease A have been characterized by structural and kinetic studies. In addition to the active site (p₁ ), the role of other noncatalytic phosphate-binding subsites in the correct alignment of the polymeric substrate has been proposed. p₂ and p₀ have been described as phosphate-binding subsites that bind the phosphate group adjacent to the 3′ side and 5′ side, respectively, of the phosphate in the active site. In both cases, basic amino acids (Lys-7 and Arg-10 in p₂ , and Lys-66 in p₀ ) are involved in binding. However, these binding sites play different roles in the catalytic process of ribonuclease A. The electrostatic interactions in p₂ are important both in catalysis and in the endonuclease activity of the enzyme, whilst the p₀ electrostatic interaction contributes only to binding of the RNA.     

具有三个CM公共值的亚纯函数的唯一性

本文指出仪洪勋和Brosch G在具有三个判别的CM公共值的亚纯函数的唯一性定理中,关于对数函数的导数是整函数的推导,可以用指数函数求导的方法来证明.改进了仪洪勋和Brosch G关于重值与唯一性定理.     

Pain relief by xenograft of subarachnoid microencapsulated bovine chromaffin cells in cancer patients

The bovine chromaffin cells (BCC) implanted into the subarachnoid space can release analgesic substances such as opioid peptides and ealeeholamines. Clinical trials have provided the evidence that the implantation of polyvinylchloride ( PVC) hollow fiber encapsulated BCC by surgery can relief the pain in cancer patients. In the present study, BCC were encapsulated in alginate-polylysine-alginate (APA) mieroencapsules which protect the grafting of xenogeneic cells from host immune system anil allow BCC to function effectively without using immunosuppression agents. The microencapsulated BCCs (5 X 106~—8 X 106) were transplanted into the subarachnoid space I^._s of 17 patients who suffered from chronic cancer pain and had to have long-term administration of analgesics. The pain scores and morphine intake tesl showed that microencapsulated BCC graft totally stopped the chronic pain in three of the patients over a period of 200 days and in the other three over a period of 100 days. The resulls suggesl thai APA microencapsulated BCC xenotransplantation could be a novel alternative approach to managing pain of cancer patients.