抗胃癌细胞系单克隆抗体PD4的初步研究

以胃癌细胞系MGC803免疫Balb/c小鼠,取其脾细胞与小鼠骨髓瘤细胞NS-1融合。经选择培养、筛选及克隆化,获得恒定地分泌抗胃癌细胞系单克隆抗体(MoAb)的杂交瘤细胞系PD4。MoAb PD4与3/4胃癌细胞系有强结合反应,与4/4肺癌细胞系有弱结合反应,但与淋巴细胞、ABO红细胞、骨髓细胞、二倍体成纤维细胞及经检测的其他肿瘤细胞均无反应。PD4抗原主要表达于靶细胞的膜上,不耐热,为分子量40kD的蛋白性抗原。该抗原与HLA抗原系统,血型抗原系统无关,亦不同于其他作者所报告的其他胃癌相关抗原。     

Epithelial cytoskeletal framework and nuclear matrix-intermediate filament scaffold: three-dimensional organization and protein composition

Madin-Darby canine kidney (MDCK) cells grow as differentiated, epithelial colonies that display tissue-like organization. We examined the structural elements underlying the colony morphology in situ using three consecutive extractions that produce well-defined fractions for both microscopy and biochemical analysis. First, soluble proteins and phospholipid were removed with Triton X-100 in a physiological buffer. The resulting skeletal framework retained nuclei, dense cytoplasmic filament networks, intercellular junctional complexes, and apical microvillar structures. Scanning electron microscopy showed that the apical cell morphology is largely unaltered by detergent extraction. Residual desmosomes, as can be seen in thin sections, were also well- preserved. The skeletal framework was visualized in three dimensions as an unembedded whole mount that revealed the filament networks that were masked in Epon-embedded thin sections of the same preparation. The topography of cytoskeletal filaments was relatively constant throughout the epithelial sheet, particularly across intercellular borders. This ordering of epithelial skeletal filaments across contiguous cell boundaries was in sharp contrast to the more independent organization of networks in autonomous cells such as fibroblasts. Further extraction removed the proteins of the salt-labile cytoskeleton and the chromatin as separate fractions, and left the nuclear matrix-intermediate filament (NM-IF) scaffold. The NM-IF contained only 5% of total cellular protein, but whole mount transmission electron microscopy and immunofluorescence showed that this scaffold was organized as in the intact epithelium. Immunoblots demonstrate that vimentin, cytokeratins, desmosomal proteins, and a 52,000-mol-wt nuclear matrix protein were found almost exclusively in the NM-IF scaffold. Vimentin was largely perinuclear while the cytokeratins were localized at the cell borders. The 52,000-mol-wt nuclear matrix protein was confined to the chromatin- depleted matrix and the desmosomal proteins were observed in punctate polygonal arrays at intercellular junctions. The filaments of the NM-IF were seen to be interconnected, via the desmosomes, over the entire epithelial colony. The differentiated epithelial morphology was reflected in both the cytoskeletal framework and the NM-IF scaffold.     

Thermodynamic stability of proteins in salt solutions: A comparison of the effectiveness of protein stabilizers

The denaturation of proteins by guanidine hydrochloride was studied in the presence of different concentrations of stabilizing salts, namely potassium phosphate, ammonium sulfate, and potassium acetate. The denaturation transition was followed by observing changes in the peptide circular dichroism atpH 7.0 and 25°C. From these results the free energy of stabilization for the process native denatured was determined. It was found that the stabilizing power of the anions increased in the order acetate < sulfate < phosphate, in agreement with the anionic lyotropic series. Ribonuclease A, which is known to have a site that can bind either a phosphate or a sulfate ion, showed a larger stabilization by these anions than that for lysozyme, pepsinogen, and myoglobin.     

Long-acting contraceptive agents: Norethisterone esters of arylcarboxylic acids

The synthesis of esters of norethisterone (17α-ethynyl-17β-hydroxy-estr-4-en-3-one) with acids containing a benzene ring is described, two methods of esterification being compared in terms of yield and convenience. The activities of these esters as long-acting contraceptive agents have been evaluated.     

9-Hydroxydodecanoic acid,an acid from Blepharis sindica seed oil

A hitherto unknown hydroxy acid has been isolated from Blepharis sindica seed oil has been characterized as 9-hydroxydodecanoic acid by IR, NMR and mass spectral studies. The structure of this acid was further supported by its chemical transformations.     

Partial characterization of the phosphotransferase system of human central-nervous-system myelin.

The phosphotransferase system of human central-nervous-system myelin was investigated. Evidence obtained indicated the presence of at least two different phosphotransferase systems (cyclic nucleotide-dependent and -independent) in myelin, which were found to be firmly associated with the membrane. The cyclic AMP-dependent kinase of myelin and white-matter cytosol preferentially phosphorylated certain histone fractions and displayed only modest activity with basic protein as substrate. On the other hand, the cyclic nucleotide-independent system showed specificity toward basic protein. Its activity was not only dependent on Mg2+ but it was greatly enhanced by this bivalent cation. Whereas the cyclic nucleotide-dependent kinase could be extracted with buffers containing Triton X-100, the bivalent cation-regulated kinase resisted solubilization from myelin under these conditions.     

Fluorouracil and the isolation of mutants lacking uridine phosphorylase in Escherichia coli: location of the gene

Summary A selective technique is described for the isolation of mutants of Escherichia coli lacking uridine phosphorylase and the location of the gene specifying this enzyme on the bacterial chromosome is determined. Using strains with appropriate lesions it is shown that there are three routes via which 5-fluorouracil can be converted to compounds which inhibit cell growth.     

On the carbohydrate—protein linkage group in vitreous humor hyaluronate

Fractional molar ratios of serine, threonine and aspartic acid to neutral sugars in the purified bovine vitreous humor hyaluronate, and a 4–5-fold increase in the percentage of these amino acids and the absence of sugar alditols in hyaluronate reduced with NaBH₄---PdCl₂ after alkali treatment indicated the absence of a carbohydrate—protein linkage. Gel filtration behavior, a decrease in intrinsic viscosity of reduced hyaluronate to about one-half and a significant decrease in its specific rotation suggested that the two antiparallel chains of the hyaluronate double helix may come apart upo reduction. The vitreous humor hyaluronate contained 109.2 ppm of “bound” silicon. It is suggested that the bound silicon may bridge the two antiparallel chains through the neutral sugars and/or through the hydroxyl group of the uronic acid moiety.