摘要:

AbstractWe have examined the association of DNA polymerase α activity with the nuclear matrix prepared by different techniques from mouse erythroleukemia cells. At variance with the data obtained using other cell types we have found that only a small amount (less than 2%) of nuclear DNA polymerase α activity resisted extraction with high‐ionic strength buffers, even if nuclei were heat‐stabilized by incubation at 37°C for 45 min prior to subfractionation. The recovery of DNA polymerase α activity bound to the matrix was unaffected by the type of extracting agent used (NaCl or (NH4)2SO4), by the extraction sequence or by the method employed for obtaining nuclei. These results could indicate that in some types of cells the nuclear matrix is not involved in DNA repl

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1113

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe association between intermediate filaments (IF) and microtubules (MT) has been demonstrated by several experiments usingMTinhibitors and by microinjecting specific antibodies. The actin cytoskeleton has recently been assigned a role in this process of drug inducedIFcollapse. However, this was not found to be true in large cells with irregular morphology. For instance, in early passage diploid fibroblasts of human origin and in armadillo cell lines, where the cells are large, irregular in shape and exhibit prominent stress fibers (SF), depolymerization ofMTwith nocodazole did not lead to collapse ofIF. Instead, theIFformed bundles of coils that seemed to associate with theSF. Disintegration of the SF with cytochalasin B led to the collapse of theIF. It appears that the actin organization in such large cells with extensiveSF, is not as contractile as in typical spindle shaped fibroblasts which have relatively less stable actin organization. The stableSFmay actually preventIFcollapse.

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1114

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThis is the first report of the elimination of confronting cisternae (CC), prominent organelles in dividing HeLa cells, upon experimental manipulation of the cells. CC are lost when a double thymidine block is employed to synchronize cell division. This observation is consistent with the hypothesis that the occurrence of CC in some fetal cells and in selected tumor cells depends on the speed at which the cells cycle through mitosis. If thymidine blocks DNA synthesis and arrests cells at the G1/S interface, then thymidine probably has an indirect effect on CC. This paper reports the effect of thymidine on the occurrence of CC and briefly discusses how inhibitors of membrane synthesis or microtubule polymerization may affect the occurrence of CC during mitosis.

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1115

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe structural changes in erythrocytes membranes were examined before and after the second heat shock of erythrocytes. Electrophoretic separation of protein erythrocyte membranes for cells incubated at 48.5°C was different from control i.e. from erythrocytes incubated at 37°C. No quantitative or qualitative changes were spotted in comparison with protein membranes isolated from the erythrocytes following single or double heat shock.Fluidity of erythrocytes membranes was determined by using spin labels, 5‐doxylstearic acid and 16‐doxylstearic acid. The membranes were more rigid in their hydrophobic regions after incubation of cells at 44°C. It can be suggested that erythrocyte membranes play some role in thermotolerance and heat damage of enuclate

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1116

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractPrimary cultures of human fetal oesophageal cells were set up and maintained for 45 days. Epithelial cells were the dominant cell type in the culture for the first four weeks. Thereafter, both epithelial cells and fibroblasts were seen with the fibroblasts becoming the dominant cell type by the 6th week and until the cultures degenerated. The tritiated thymidine uptake showed an upward trend from day 10 up to day 30, with peak uptake at day 30 in the untreated, B(a)P treated and OAc treated cultures and decreased thereafter. The thymidine uptake levels were significantly higher in the B(a)P treated cultures when compared with levels in the untreated cultures. A concurrent increase/decrease was also seen in the cell number in all the three groups of cultures. Cultures with B(a)P and DMN‐OAc showed significantly higher AHH levels as compared with untreated cultures. These results indicate that the human fetal oesophageal cells could be viably maintained under in vitro conditions for long periods of time and also showed capacity to metabolise the carcinogens through aryl hydrocarbon hydroxylase activit

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1117

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractChicken ovalbumin and bovine serum albumin (BSA) were compared as supplements to the basal medium, L‐15, for the serum‐free cultivation of the Chinook Salmon Embryo cell line, CHSE‐214. Unlike L‐15 alone, ovalbumin and some commercial BSA preparations allowed cell proliferation and development of confluent monolayer cultures. However, only a fatty acid‐free BSA (2%) supported continuous proliferation for two years through approximately 15 subcultivations. For this, subcultivation was achieved with non enzymatic cell dissociation solutions. Also, new serum‐free subcultivation techniques were developed that utilized avian egg white trypsin inhibitors to terminate the action of either bovine or cod trypsin. Finally, CHSE‐214 were successfully cryopreserved in 2% BSA, allowing all cell cultivation steps to be performed in the a

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1118

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA major limitation to the clinical usefulness of cancer chemotherapy is the onset of acquired drug resistance, in which the effectiveness of a drug such as Doxorubicin (DOX), used in a wide variety of neoplasms, diminishes following repeated administration. Resistance is associated with drug exclusion from tumour cell nuclei. New analogues of DOX have been synthesised to reduce patient cardiotoxicity and to increase anti‐tumour activity. More recently, a 2‐fluoroglycoside of DOX (ME2303) has been shown to be more resistant to glycolysis and has marked anti‐proliferative effects on DOX‐resistant tumours. The aim of the current study was therefore to determine the intracellular localisation of ME2303 in drug sensitive and resistant human ovarian cancer cell aggregates by mapping fluorine, as a means of understanding the complex mechanisms of drug resistance. Cell aggregates of the human ovarian cell line A2780 and its DOX‐resistant subline 2780AD were cultured for 1hr in 5μM of the drug ME2303, then chemically fixed and embedded in Lowicryl K4M using alcohol dehydration at −20°C. Ultrathin sections (40‐50nm) were examined on a Zeiss TEM 902 energy filtering electron microscope using 80Kv at a magnification of 12,000x. Fluorine maps were generated using the two window method by collecting two integrated images above and two integrated images below the K ionisation edge for fluorine (685eV) with a 15eV window. Image sequences were collected within 20sec to minimise the effects of mass loss from the specimen via a Dage SIT 66 video camera connected to a DT 2861 video interface board (512x512 pixels with 256 grey levels) within a 486 PC. In the A2780 cell line, fluorine was found to be distributed diffusely within the cytoplasm and at discrete sites within the nucleus. In contrast, fluorine in the 2780AD subline (co‐cultured with 1.4μM DOX to maintain resistance) was found to be largely associated with the peri‐nuclear Golgi region and with mitochondria, but was also found within cell nuclei, along the inner nuclear envelope and in the nucleolus. The intra‐nuclear localisation of fluorine suggests that even in the presence of DOX, ME2303 can mediate anti‐proliferative activity in DOX resistant human ovarian cancer cells by effecti

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1119

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1120

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1121

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1993.1122

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY