Selective colocalization of lipid peroxidation and protein thiol loss in chemically induced hepatic preneoplastic lesions: the role of γ-glutamyltranspeptidase activity

A number of studies indicate that cell proliferation can be modulated by changes in the redox balance of (soluble and protein) cellular thiols. Free radical processes, including lipid peroxidation (LPO), can affect such a balance, and a role for LPO in multistage carcinogenesis has been envisaged. The present study was aimed to assess the relationships between the protein thiol redox status and the LPO process in chemically induced preneoplastic tissue. The Solt-Farber's initiation-promotion model of chemical carcinogenesis in the rat liver was used. In fresh cryostat sections, preneoplastic lesions were identified by the reexpression of γ-glutamyltranspeptidase (GGT) activity. In serial sections, different classes of protein thiols were stained; in additional sections, LPO was elicited by various prooxidant mixtures and determined thereafter by the hydroxynaphthoic hydrazide-Fast Blue B procedure. The incubation of sections in the presence of chelated iron plus substrates for GGT activity leads to the development of LPO in selected section areas closely corresponding to GGT-positive lesions, indicating the ability of GGT activity to initiate LPO. Protein-reactive thiols, as well as total protein sulfur, were decreased by 20–25% in cells belonging to GGT-positive preneoplastic nodules, suggesting the occurrence of oxidative conditions in vivo. The incubation of additional adjacent sections with the prooxidant mixture H₂O₂ plus iron(II), in order to induce the complete oxidation of lipid present in the section, showed a decreased basal concentration of oxidizable lipid substrate in GGT-rich areas. The decreased levels of both protein thiols and lipid-oxidizable substrate in GGT-positive nodules suggest that the observed GGT-dependent path-way of LPO initiation can be chronically operative in vivo during early stages of chemical carcinogenesis, in cells expressing GGT as part of their transformed phenotype.     

Synthesis of optically active diols using an efficient polymer bound cinchona alkaloid derivative

A new insoluble polymer containing a Cinchona alkaloid derivative has been synthesized and used as chiral ligand in the heterogeneous enantioselective dihydroxylation of olefins. It is shown that the enantioselectivity of the optically active diols obtained from both aliphatic and aromatic substrates is always comparable to that observed in the homogeneous phase under the same reaction conditions. A method for evaluating the enantiomeric excesses of the optically active products is also described. © 1995 Wiley-Liss, Inc.     

Biotransformation of diphenyl ether by the yeastTrichosporon beigelii SBUG 752

Trichosporon beigelii SBUG 752 was able to transform diphenyl ether. By TLC, HPLC, GC, GC-MS, NMR- and UV-spectroscopy, several oxidation products were identified. The primary attack was initiated by a monooxygenation step, resulting in the formation of 4-hydroxydiphenyl ether, 2-hydroxydiphenyl ether and 3-hydroxydiphenyl ether (48:47:5). Further oxidation led to 3,4-dihydroxydiphenyl ether. As a characteristic product resulting from the cleavage of an aromatic ring, the lactone of 2-hydroxy-4-phenoxymuconic acid was identified. The possible mechanism of ring cleavage to yield this metabolite is discussed.     

Chemical behaviour of cytidine 5'-monophospho-N-acetyl-beta-D-neuraminic acid under neutral and alkaline conditions

The chemical behaviour of CMP-N-acetylneuraminic acid under neutral and different alkaline conditions has been investigated. The products formed were isolated by ion-exchange chromatography and gel filtration and analysed by colorimetric methods, thin-layer chromatography, combined gas-liquid chromatography/mass spectrometry and/or 360-MHz 1H-NMR spectroscopy. A maximum stability of CMP-N-acetylneuraminic acid was observed at pH8-11. In the tested pH range of 6-13, CMP and N-acetylneuraminic acid were formed in variable amounts as decomposition products. 2-Deoxy-2,3-dehydro-N-acetylneuraminic acid was produced at pH greater than 7; the amount of this substance increased with increasing pH. In anhydrous triethylamine its yield was 50%. A new neuraminic acid derivative, N-acetyl-beta-D-neuraminic acid 2-phosphate, could be isolated from the mixture of alkaline decomposition products of CMP-N-acetylneuraminic acid. The yield of this compound was maximum 22% in anhydrous triethylamine. Because 2-deoxy-2,3-dehydro-N-acetylneuraminic acid was formed under simulated physiological conditions, it is assumed that this compound, which occurs in tissues and fluids of man and animals, is derived from CMP-N-acetylneuraminic acid non-enzymically also under conditions in vivo.     

The distribution of keratin type intermediate filaments in human breast cancer. An immunohistological study

Antibodies to different intermediate filament proteins can be used to distinguish cells of epithelial, mesenchymal, muscle, glial and neuronal origin. Antibodies to prekeratin which characterize cells of epithelial origin, and antibodies to vimentin which recognize cells of mesenchymal origin have been used to study twenty cases of breast carcinoma (sixteen infiltrating ductal carcinomas and four infiltrating intraductal carcinomas), two cases of cystic breast disease, two fibroadenomas and one case of benign cystosarcoma phylloides. The prekeratin and vimentin were detected using specific antibodies to these proteins by immunofluorescence microscopy using alcohol fixed paraffin-embedded tissues. In eighteen out of the twenty carcinomas the tumor cells were strongly and specifically stained by antibodies to prekeratin. DIfferent tumors gave different patterns of prekeratin staining. In contrast, when the same specimens were tested with the vimentin antibody, the tumor cells were unstained, and instead only the usual strong staining to fibroblasts and blood vessels in the stroma was observed. In cystic breast disease, fibroadenomas, and benign cystosarcoma phylloides, cells of epithelial origin were strongly stained by the prekeratin but not by the vimentin antibody.     

Insecticidal activity ofBacillus thuringiensis strains against the egyptian cotton leaf wormSpodoptera littoralis [Lep.: Nocutidae]

Among more than 50 isolates ofBacillus thuringiensis Berliner (B.t.) tested, 7 incited 100% mortality when 2nd instar larvae ofSpodoptera littoralis Boisduval were fed on alfalfa leaves dipped in a spore-crystal suspension of 10⁸ colony forming units/ml. Among those isolates,B.t. 24 demonstrated the highest activity. Larvae of instars 1 and 2 were the most susceptible toB.t. Susceptibility decreased with larval development. However, larvae of all instars were killed by isolateB.t. 24. Larvae that survived after feeding withB.t. 24 were retarded and fed less. Their weight relative to the controls was lower as the spore concentration on the leaves on which they fed was higher. Survival of the spores in the field dropped drastically to 2% after 4 days. Insecticidal activity of the sprayed suspension on those leaves, however, remained significant.B.t. 24 was also effective against larvae on cotton plants in the greenhouse and in a preliminary field experiment. Numbers of colony forming units recovered from leaves dipped in suspension of various spore concentrations showed significant correlation with the initial concentrations as did sprayed leaves. However, colony forming units recovered from sprayed leaves were 5–7.5 fold lower than from dipped leaves. Dipped cotton leaves showed 3.1×10^?5 ml attached to 1 mm² leaf surface whereas sprayed ones had 6×10^?6 ml. Those data are important for the determination of spore concentrations in suspensions required for spraying. The isolateB.t. 24 was serotyped byH. de Barjac as H-6B. thuringiensis entomocidus.     

Independent regulation of collagen types by chondrocytes during the loss of differentiated function in culture

Collagen phenotypes were determined for rabbit articular chondrocytes in cartilage slices and first through fifth monolayer cultures. During the first 24 hr of slice culture, chondrocytes exhibited the following collagen phenotype: 96% type II, 3% X₂Y and 1% type III. In primary monolayer culture, no other types of collagen were added to this differentiated chondrocyte phenotype; however, the synthesis per cell of each of the expressed collagens was stimulated. By the fifth day of primary culture, X₂Y synthesis increased 10 fold, and by the eighth day, a further 4 fold. In contrast, the synthesis of collagen types II and III showed no change by the fifth day, but increased 7 fold by the eighth day. These results suggest independent regulation of X₂Y in this situation. In a separate experiment, first through fifth cultures were studied. The synthesis per cell of type II collagen declined steadily and essentially ceased by the fifth culture, indicating the loss of differentiated function by these chondrocyte progeny. The loss of type II synthesis was not quantitatively replaced by the synthesis of type I trimer and type I collagen which was first detected in the third culture. While these qualitative changes in phenotype occurred, the stimulated rate of type III collagen synthesis did not change and that of X₂Y declined only slightly. Thus the termination of type II synthesis did not significantly alter the synthesis of the other collagens produced by differentiated chondrocytes. The final “de-differentiated” phenotype was 41% type I, 25% X₂Y, 20% type I trimer, 13% type III and 1% type II.