摘要:

AbstractThe NAD‐ and NADP‐dependent aldehyde dehydrogenase (ALDH) activities were evaluated in two rat hepatoma cell lines, namely the well‐differentiated MH1C1 line and the less differentiated HTC line. Each activity was determined in parallel in isolated rat hepatocytes, for comparison. The aliphatic aldehyde acetaldehyde (ACA) and the aromatic aldehyde benzaldehyde (BA) were used as substrates. With the first substrate the ALDH activities found in the crude cytoplasmic extracts were lower in hepatoma cells than in normal hepatocytes, especially when measured with NADP as coenzyme (ACA/NADP). Otherwise, with benzaldehyde as substrate the NAD‐dependent enzyme activity (BA/NAD) was increased about 9‐fold in HTC cells over hepatocytes and decreased in MH1C1 cells, while the NADP‐dependent (BA/NADP) activity was increased 38‐ and 2·5‐fold in HTC and MH1C1 cell lines, respectively. Studies on the subcellular distribution of these enzyme activities showed that the activity measured with acetaldehyde and NAD (ACA/NAD) was almost equally distributed between the cytosol and the subcellular particles in the three cell populations, but the ACA/NADP activity was shifted towards the cytosolic compartment in hepatomas, especially in HTC cells. The BA/NAD and BA/NADP ALDH activities found in the organelles of hepatoma cells were markedly reduced in comparison with hepatocytes, in favour of the cytosol. The most striking difference between the normal and the transformed cells was the 94‐fold increase over hepatocytes of the BA/NADP activity, found in the cytosolic fractions of HTC cells. MH1C1 cells showed a less pronounced (7·5‐fold) enhancement of this tumour‐associated specific activity. These results confirm that the cytosolic NADP‐dependent benzaldehyde dehydrogenase activity can be considered as a tumour marker, the activity being inversely correlated with the degree of differentiation of th

ISSN:0263-6484    

DOI:10.1002/cbf.290090302

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractIn vitrostudies of the effects of recombinant granulocyte macrophage‐colony stimulating factor (rGM‐CSF) on freshly obtained human leukemia cells were conducted to determine if there is a relationship between the effects of this growth factor on the proliferative characteristics of leukemia cells and on their incorporation of cytosine arabinoside (araC) into DNA. While rGM‐CSF was found to be able to stimulate both leukemia cell proliferation and araC incorporation, for individual leukemia specimens there was no consistent relationship among these effects. In some specimens proliferation was stimulated without an increase in araC incorporation. The reverse was also observed. These studies demonstrate the difficulty in identifying assays capable of predicting the clinical effects of growth factors on leukemia cells in patients since the effectin vitrovary with the

ISSN:0263-6484    

DOI:10.1002/cbf.290090303

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effects of 4‐hydroxy‐2,3‐trans‐nonenal (HNE) and nonanal on the activity of phosphoinositide‐specific phospholipase C of rat neutrophils have been studied in parallel with their action on neutrophil oriented migration. Concentrations of HNE ranging from 10−7to 10−5Msignificantly stimulated the oriented migration of rat polymorphonuclear leukocytes. HNE stimulated both the basal and GTP gamma S‐induced phospholipase C activity when used at concentrations between 10−8and 10−6M. Nonanal was devoid both of chemotactic activity and of any action on phospholipase C activity. The effect of GTP gamma S on the stimulation of phospholipase C induced by HNE was higher when the lowest dose of the aldehyde was used; the finding of an additive effect between 10−8MHNE and 2 × 10−5MGTP gamma S suggests that the two compounds may share a final common pathway of action.These results suggest that the chemotactic activity of HNE might be mediated, like that of other more well‐known chemoattractants, by the stimulation of phosphoinositid

ISSN:0263-6484    

DOI:10.1002/cbf.290090304

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

Abstract3H‐Labelled kappa‐elastin peptides (kE:75 kDa molecular weight) were shown to bind to confluent human skin fibroblast (HSF) cultures in a time‐dependent and saturable manner. Scatchard analysis indicated the presence of high affinity binding sites withkD= 2·7 × 10−10Mand 19 000 sites per cell. Binding of kE to its receptor on HSF accelerates and intensifies the adhesion of insoluble elastin fibres (iE) to confluent HSF. Optimal effect was attained for a kE concentration of 0·3 × 10−9Mclose tokD. This stimulatory effect of kE on the binding of iE to HSF could be inhibited by neomycin, retinal and pertussis toxin, substances which act at different levels of the transduction mechanism following the activation of the receptor and the subsequent triggering of cell biological events (chemotaxis, modification of calcium fluxes). The stimulation of iE adhesion to HSF induced by kE as well as kE binding to the cells could by inhibited by lactose and laminin but not by Arg‐Gly‐Asp‐Ser (RGDS) peptides. This indicates that the elastin peptide receptor on HSF possesses lectin‐like properties and shares homology with the laminin receptor as also shown for other cell types. None of the substances tested, that is inhibitors of the transduction mechanism, lactose, laminin and Arg‐Gly‐Asp‐Ser (RGDS) peptides were shown to interfere significantly with the binding of iE (in the absence of added kE) to confluent HSF. The proteins adhering strongly to elastin fibres were isolated by a sequential extraction procedure and the final hydrochloride guanidinium‐DTT extract was analysed by SDS–PAGE under reducing conditions, Western blots using specific antibodies against several connective tissue proteins and affinity for [3H]‐kE following nitrocellulose electro‐transfer of proteins. Fibronectin, vitronectin, tropoelastin(s), and a 120 kDa cysteine rich glycoprotein previously designated as elastonectin were identified. Among these proteins, [3H]‐kE was found to bind exclusively to a 65 kDa protein that could be eluted selectively from elastin fibres with a neutral buffer containing 100 mM lactose. Therefore the elastin peptide receptor on human skin fibroblasts shares properties with the elastin receptor characterized from other cell types. Conformational differences between elastin peptides and elastin fibres could explain the differences in the mechanisms of interactions between elastin fibres and elastin peptides with HSF in culture. The stimulatory effect of elastin‐derived peptides on the adhesion of elastin fibres to HSF could have implications in the

ISSN:0263-6484    

DOI:10.1002/cbf.290090305

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe incubation of double‐labelled ([14C]‐glycerol and [3H]‐myoinositol) keratinocytes with 13‐cis retinoic acid induced the transient and simulataneous release of [3H]‐inositol trisphosphate ([3H]‐InsP3) and [14C]‐diacylglycerol ([14C]‐DAG) indicating that a possible mode of action of this retinoid on murine keratinocytes may be at least in part the early trasient release of the two putative messengers (InsP3and DAG) from phosphatidylinositol‐4,5 bisphosphate (PtdIns4, 5P2). In contrast, the preincubation of the keratinocytes with 12‐O‐tetradecanolyphorbol‐13‐acetate (TPA) prior to incubation with 13‐cis‐RA suppressed the 13‐cis‐RA‐induced release of [3H]‐InsP3and [14C]‐DAG. The specificity of the TPA effect was established by the lack of effect of the biologically inactive 4α‐phorbol 12, 13‐didecanoate. Furthermore, the incubation of the TPA‐primed keratinocytes with 13‐cis‐RA caused a delayed and sustained accumulation of [14C]‐DAG. An exploration of the source of this late relase of [14C]‐DAG revealed that this [14C]‐DAG was released from non‐inositol containing phospholipids, particularly, phosphatidylcholine. This latter DAG released in the TPA‐primed cells correlated with the translocation of the cytoplasmic protein kinase C (PKC) activity to the membrane associated PKC activity. Taken together, these results suggest that alteration of PKC activity, presumably induced by DAG released from non‐inositol phospholipids, may play a major role in the TPA‐induced negative feedback inhibit

ISSN:0263-6484    

DOI:10.1002/cbf.290090306

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractATP translocation into mitochondria isolated from halothane‐sensitive pig (HP) muscle was dramatically reduced compared with normal pigs (NP). To determine if this was due to a decreased amount of ATP translocase in the mitochondrial membranes, or a structural modification of this protein, an electrophoretic study was undertaken. Total proteins and purified translocase preparations from (NP) and (HP) mitochondria were analysed by SDS gel electrophoresis. In the two type of mitochondria no significant differences were observed either in the amount of ATP translocase or in the molecular weight. Also, neither nonequilibrium pH gradient gel electrophoresis nor the analysis of peptides produced by limited proteolysis revealed any structural difference between the two types of protein. On the basis of these results, the depressed translocase activity observed in (HP) mitochondria cannot be explained by a reduced amount of the nucleotide translocase, nor a structural alteration of this protein. Possible inhibition of (HP) translocase activity by Ca2+accumulation or by other mechanisms is discusse

ISSN:0263-6484    

DOI:10.1002/cbf.290090307

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractIt has been proposed that the diamine oxidase inhibitor aminoguanidine may be a potential therapeutically important anabolic agent. An investigation was therefore made into the effects of aminoguanidine treatment with or without nutritional restriction, on cardiac and skeletal muscles containing mainly of either Type I (i.e. soleus) or Type II fibres (i.e. plantaris) or a mixture of Type I and II fibres (i.e. gastrocnemius).After 3 weeks, dietary restrictions reduced cardiac weight, protein, RNA and DNA contents by between 31 per cent and 36 per cent. Similar, but smaller, reductions were observed in the soleus (18–31 per cent), plantaris (22–34 per cent) and gastrocnemius (22–34 per cent).Aminoguanidine had no effect on the heart of the rats fedad libitum, nor did it alter the response to dietary restriction. Treatment with aminoguanidine had no overt anabolic effect on skeletal muscle, but a reduction in DNA content was observed.It was concluded that cardiac protein and nucleic acid contents are more sensitive to dietary deprivation than either anaerobic or aerobic skeletal muscles. Furthermore, aminoguanidine does not appear to promote growth or reduce catabolism as previous studies have sugg

ISSN:0263-6484    

DOI:10.1002/cbf.290090308

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThree aminoglycosidic antibiotics: tobramycin, amikacin and sisomicin were administred to rats. There was an increase in the activity ofN‐acetyl‐β‐D‐glucosaminidase (NAG) excreted in the urine and this was characterized by a change in the isoenzyme profiles eluted from DEAE–cellulose. The largest increase in NAG activity was observed following sisomicin administration due mainly to an increase in the B‐form of NAG with a concomitant fall in the intermediate (I‐form). Separation of urinary proteins by SDS‐polyacrylamide gel electrophoresis demonstrated a mixed tubular and glomerular proteinuria following administration of sisomicin. It is concluded that the separation of NAG isoenzymes and urinary proteins provides valuable additional information on the nature and severity of antibioti

ISSN:0263-6484    

DOI:10.1002/cbf.290090309

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractRenal (Na + K)‐ATPase was studied to ascertain whether it follows the pattern of adaptation of membrane‐bound enzymes that are inhibited by acute ethanol exposure and develop greater activity after chronic ethanol treatment. A colony of rats was given 20 per cent (v/v) ethanol as sole drinking solution throughout gestation, lactation and following weaning. (Na + K)‐ATPase and ouabain‐insensitive Ca2+‐ATPase activities were determined; regional distribution of these enzymes was assessed in renal cortex and outer medulla. Control rats drank tap water.(Na + K)‐ATPase in whole homogenate of kidney increased with age in controls and ethanol‐fed rats, but the latter showed higher values at every age studied. Between 15 and 60 days of age, the control group showed 2‐fold increases in cortex and 5‐fold in outer medulla, whereas ethanol‐fed rats reached a 3‐fold increase in the enzyme activity in both renal regions. Ca2+‐ATPase showed the same time course in developing kidney of both groups. Chronic ethanol treatment of adult rats resulted in an increase of (Na + K)‐ATPase activity in cortex and outer medulla, but no change in other ATPases.Since an earlier maturational development of renal (Na + K)‐ATPase was displayed by ethanol‐fed rats, underlying mechanisms that may account fo

ISSN:0263-6484    

DOI:10.1002/cbf.290090310

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290090313

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY