摘要:

ABSTRACTWe earlier demonstrated that hsp68 is deficiently induced upon stress in the glucocorticoid‐resistant, dedifferentiated Reuber rat hepatoma clone 2 cells, but is strongly activated in the differentiated, glucocorticoid‐sensitive Faza 967 cells from which clone 2 was derived. We used the two cell types to address the questions whether hsp68 is specifically involved in the development of thermotolerance and/or thermoresistance or drug resistance. Our experiments show that clone 2 cells were not protected from the killing effect of heat by pretreatment with sodium arsenite, whereas Faza 967 cells were. These results strongly suggest a role of hsp68 in the development of thermotolerance in hepatoma cells. Stable heat‐resistant variants of clone 2 cells were also isolated, where an increased basal expression of several hsps was observed together with the (at least partial) restoration of the heat‐inducibility of hsp68. These results suggest that several hsps are needed to protect the critical biological processes at high temperature. The heat‐resistant hepatoma cells also became resistant to several anticancer drugs. The multidrug resistance of the hepatoma variants correlates with the overexpression of the plasma membrane P‐glycoprotein. Our results showing that severely stressed hepatoma cells overexpressed the mdr gene(s) raise the possibility that the P‐gp may participate in protection against environmental stress

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1087

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTFour major non‐collagenous bone proteins were localised by single and double immuno‐histochemistry during de novo mineralisation and bone resorption. Both osteopontin and bone sialoprotein were localised ahead of the mineralisation front, suggesting that both proteins are necessary for the initiation of bone mineralisation. This supports previous suggestions that bone sialoprotein acts as a crystal nucleator. The role of osteopontin is less certain, but might be related to ensuring that only the right type of crystal is formed. Osteocalcin and osteonectin were not present in areas of first crystal formation, but were present in the fully mineralised matrix. Their role may be to control the size and speed of crystal formation.Osteopontin, bone sialoproteins and osteocalcin (but not osteonectin) were also present at reversal lines. Interpreting this localisation together with information from the literature, the following functions are suggested during resorption: Osteocalcin may act as a chemoattractant for osteoclasts, while both osteopontin and bone sialoprotein may facilitate the binding of osteoclasts via the arg‐gly‐as

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1088

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTSynthesis of lactoferrin and casein by the bovine mammary gland was determined in an experimental model where lactation was maintained in one mammary half, while involution was induced in the contralateral half. Culture of explants with prolactin had no consistent effect on synthesis of casein or lactoferrin in tissue from either mammary half. Endotoxin and tumor necrosis factor‐α generally decreased synthesis of casein and lactoferrin, suggesting that these inflammatory mediators are not directly responsible for increasing lactoferrin synthesis during mammary inflammation or involution. Synthesis of lactoferrin was increased and casein decreased in the involuting mammary half vs. the lactating half. These results suggest that local factors in the mammary gland play a role in the regulation of lactoferrin synthesis during involuti

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1089

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTWe have previously shown that thrombin reverses the growth inhibition caused in human fibroblasts when a cell‐surface proteinase is inhibited. A similar result was obtained with asynthetic thrombin receptor agonist peptide, which mimics the conformational change resulting from receptor cleavage by thrombin. Consideration of the effects of the growth‐related proteinase on intracellular second messengers indicates that cleavage of the thrombin receptor by this endogenous proteinase is not a significant event for normal fibroblast growth in culture. Inhibition of the growth‐related proteinase also fails to block the mitogenic action of bombesin. In conjunction with earlier results, this suggests that the intracellularpoint of action of GRP inhibition may be at, or closely connected with, the receptor‐linked tyrosine kinases, and evidence for inhibition of protein phosphorylation following from GRP inhibition is pr

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1090

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTImmunofluorescence microscopy shows that unlike cytoplasmic microtubules (MT), vimentin‐type intermediate filaments (IF) are collected into ring‐shaped structures in affected fibroblasts. The altered IF organization could be observed in monolayers of polarized fibroblasts in the prolonged stationary growth phase and after replating ‐ upon their initial spreading. Transition from a discoid to an extended cellular form is accompanied by centrifugal dislocation of ring‐shaped IF structures towards the cell's active edge with gradual restoration of the radial fibrillar vimentin network. Spreading of affected cells occurred more slowly than that of control fibr

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1091

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe nuclear matrix from chicken liver cells contains a small amount of glycoproteins recognized by Concanavalin A. These proteins are present not only in the peripheral matrix, but also in the internal one. In this latter localization many glycoprotein species appear, by cross‐linking experiments, to be placed in the proximity of DNA. The effect of a partial enzymatic deglycosylation of matrix preparations suggests that these proteins contribute to the stabilization of the native matrix structur

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1092

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThis electron microscopical study was performed in order to follow the endocytic pathway of horseradish peroxidase and colloidal gold tracers and to determine the involvement of endocytosis in postnatal differentiation in superficial cells of the mouse urinary bladder epithelium. Morphometric analyses of late endosomes/multivesicular bodies from day of birth to day 25 were performed. The internalisation and intracellular transport of luminal plasmalemma to multivesicular bodies via endocytic vesicles, early endosomes and pleomorphic compartments was established. Dynamic changes in endocytic activity took place within the first few days of postnatal differentiation. During this period the number of multivesicular bodies changed in an inverse ratio to their size. After the third day endocytic activity gradually approached the low rate of adult urothelium.

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1093

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe micronucleus test (MNT) was applied in the epithelial cells from the bladder of mice treated with benzo(a)pyrene (BaP), 2‐acetylaminofluorene (2‐AAF) and cyclophosphamide (CP). Micronuclei (MN) were scored at different time on Feulgen and fast green stained smear preparations of exfoliated cells. These cells were obtained by scraping the internal surface of the bladder. The tested compounds gave the maximal response at 7‐10 days after treatment. The number of MN in epithelial cells was dose dependent. These results suggest that exfoliated bladder cells from mice can be used as indicators for genotoxic damage in proliferating cell popula

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1094

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTA change in glucose concentration in an Ehrlich ascites carcinoma cell suspension from 0.1 mM to 20 mM causes a more than 50‐fold stimulation of the rate of ribosomal RNA synthesis. Such an effect occurs without any dramatic effect on the rate of protein synthesis in cells. This process parallels a decrease in intracellular pH which may be a reason of Na+/H+‐antiport activat

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1095

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1096

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY