Delipidated serum abolishes the inhibitory effect of serum on in vitro liposome-mediated transfection

All the standard in vitro lipofection has been routinely performed in serum-free medium as the transfection activity of liposome/DNA complexes is sensitive to the presence of serum. In this study, we have demonstrated that lipid-rich serum lipoprotein included in the transfection medium strongly inhibited the transfection activity of DC-chol liposome/DNA complexes in five different cell types (CHO, 293, A2780CP, A431 and SKBR3). The levels of inhibition by serum lipoprotein were rather greater than those by serum and varied with cell types. However, this inhibition was completely abolished by delipidation of serum. Thus, delipidated serum can be included in the transfection medium. The complexes formed in the presence of serum (zeta=-18.2+/-1.07 mV), delipidated serum (zeta=-19.6+/-0.54 mV), IgG (zeta=-21.6+/-1.92 mV) or serum lipoprotein (zeta=-10.5+/-2.33 mV) were as much negatively charged as those in serum-free medium (zeta=-21.3+/-1.60 mV). The results suggest that the inhibition of liposome-mediated transfection by serum was not associated with charges of serum proteins but with lipids or lipid-associated proteins present in serum.     

Studies on the immunoglobulin spectrum of porcine serum and colostrum

An analysis of the immunoglobulin region of porcine blood serum proved the presence of a number of protein fractions which is higher than in other animal species. The presence of antibody activity to tetanus anatoxin examined by radioimmunoelectrophoresis was found in three γ G-globulin fractions, which could be distinguished from each other, and also in two additional fractions. One of the latter was the γ-macroglobulin fraction and the other one might correspond to γ A-globulin even though its mobility was higher than the mobility of γ A-globulin of human serum. A comparison of the immunoglobulin spectrum of porcine serum, colostrum, and of the suckling pig serum after ingestion of the colostrum showed that the main component of porcine colostrum constitutes the γ G-immunoglobulin, even though the colostrum seems to contain other components of the latter which have a higher electrophoretic mobility. The antibody activity of colostrum was found only in fractions γ G and γ M. The fraction of colostrum which might correspond to γ A did not display any activity at all. The activity in suckling pig serum was also concentrated in fractions γ G and γ M.     

X射线对小鼠胰腺组织结构及血清胰岛素含量和胰淀粉酶活性的影响

探讨X射线对小鼠胰腺组织和血清胰岛素含量及胰淀粉酶活性的影响。将成年小鼠随机分为1Gy ,3Gy,5Gy实验组和0Gy对照组(每组20只),各组小鼠给予对应剂量X射线辐射(连续3d,每d一次),用生物显微技术观察胰腺组织结构的变化,用双抗体夹心法和比色法测定胰岛素含量及胰淀粉酶酶活性的变化。结果显示X射线辐射引起小鼠胰腺组织肿胀,细胞核变大,细胞变性、坏死;1Gy辐射组小鼠胰岛素含量与对照组相比有不同程度的升高,差异显著或极显著,3Gy和5 Gy辐射组小鼠胰岛素含量与对照组相比均下降,差异显著或极显著;3Gy辐射组小鼠淀粉酶活性相比对照组均有不同程度的升高,差异显著或极显著;5Gy辐射组小鼠淀粉酶活性较对照组降低,差异极显著。结果表明X射线影响小鼠胰腺组织结构及血清胰岛素含量和血清胰淀粉酶活性。     

Influence of blood and serum on the antistaphylococcal activity of lysostaphin

Zygmunt, Walter A. (Mead Johnson & Co., Evansville, Ind.), Henry P. Browder, and Peter A. Tavormina. Influence of blood and serum on the antistaphylococcal activity of lysostaphin. J. Bacteriol. 91:725-728. 1966.-Human and animal sera, and in certain instances whole blood, exhibited a minimal antagonizing effect on the antistaphylococcal activity of lysostaphin. The presence of 50% human serum only temporarily inhibited cell lysis of viable suspensions of Staphylococcus aureus by lysostaphin. The results obtained on the recovery of viable cells after exposure of S. aureus to lysostaphin actually suggest an enhancement of the antistaphylococcal activity of the antibiotic in the presence of 50% human serum. The growth-inhibitory activity of the antibiotic against 30 clinical isolates of S. aureus was only slightly depressed by the presence of 25% bovine plasma. The data suggest that some binding may occur between the antibiotic and serum proteins, but it is not of an irreversible type. Lysostaphin does not bind readily to red blood cells nor does it enter these cells to any significant degree.     

The effect of thymus extracts on phosphorus compounds in muscle and serum, and on serum calcium

1. Thymectomy in young rabbits decreased the ATP content and increased the inorganic phosphate content of skeletal muscle. The serum calcium content was decreased, whereas the inorganic phosphate content was increased. 2. The administration of a lipid fraction (TL) or protein fractions (CIF and TP) of thymus extracts to thymectomized rabbits in short-term experiments increased the ATP content of muscle and decreased the inorganic phosphate contents of muscle and serum. Serum calcium content was increased. 3. The action of the thymus extract TP was specific only on the phosphate compounds, since the increase in serum calcium concentration was also caused by the control extract from muscle. The action of the extract TL is not specific, being paralleled by the action of a control extract from muscle.     

Studies on the antigenic properties of serum albumins

Summary Bovine serum albumin (BSA) is one of the most widely studied proteins; its structure is well known and its antigenic properties have been described in animal models. The aim of our work was to evaluate the role of conformation on antigenicity of serum albumins. This study was performed using electrophoresis associated with the immunoblotting technique, where sera from children allergic to BSA were used. Data obtained in this research indicate that serum albumin antigenicity is only partially correlated to its native three-dimensional structure. Heat treatment and chemical denaturation (SDS treatment) are not able to significantly decrease its capability to bind circulating IgEs. Only the reducing treatment is able to modify the antigenicity of this protein. Moreover, a direct correlation between the cross-reactivity observed in immunoblotting between different serum albumins and the percentage of their sequence identity (phylogenetic similarity of the species) was shown.