摘要:

AbstractFactors determining the specificity of immunocytochemical (ICC) tissue stainings as well as the various tests to study these factors are discussed. Since every specificity test only deals with particular aspects of the ICC procedure, a practical sequence of known test methods is proposed, which enables the determination of the specificity of the ICC tissue staining and, after possibly needed antiserum purification steps, may result in a monospecific staining. It is made clear that such a sequence has always to include a tissue‐spectrum affinity test, in which the spectrum of tissue antigens is controlled for antibody binding. A variety of such tests, consisting of separation of tissue compounds, fixation, and ICC detection, are discussed as well as their pros and cons with respect to their predictability for the actual serum specificity in the tissue sectio

ISSN:0263-6484    

DOI:10.1002/cbf.290040102

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractInsulin receptors have been characterized in rat prostatic epithelial cells by using [125I]insulin and a variety of physicochemical conditions. The binding data at equilibrium (2h at 15°C) could be interpreted in terms of two populations of insulin receptors: a class of receptors with high affinity (Kd= 2·16 nM) and low binding capacity (28·0 fmol mg−1protein), and another class of receptors with low affinity (Kd= 0·29 μM) and high binding capacity (1·43 pmol mg−1protein). Proinsulin exhibited a 63‐fold lower affinity than insulin for binding sites whereas unrelated peptides were ineffective. The specific binding of insulin increased by about 50 per cent after 96 h of fasting; this increase could be explained by an increase of both the number of the high affinity–low capacity sites and the affinity of the low affinity–high capacity sites. These results together with previous studies on insulin action at the prostatic level strongly suggest that insulin may exert a physiological role on the prost

ISSN:0263-6484    

DOI:10.1002/cbf.290040103

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractArginine vasopressin stimulates Na+‐K+‐ATPase activity located in the rat thick ascending limb of s'Henle loop. Mammalian hypothalamus appears to produce a factor capable of inhibiting Na+‐K+‐ATPase activity in a variety of tissues. The effect of a purified rat hypothalamic extract with and without AVP on rat renal Na+‐K+‐ATPase activity was evaluated by a cytochemical technique. The hypothalamic extract alone failed to affect basal Na+‐K+‐ATPase activity throughout renal segments after 10 min exposure. Na+‐K+‐ATPase activity stimulated by AVP (1–10 fmol l−1) for 10 min was inhibited by rat hypothalamic extract over the concentration range 10−7–10−3U ml−1in a dose‐dependent manner. Complete inhibition of AVP‐stimulated Na+‐K+‐ATPase activity occurred at a hypothalamic extract concentration of 10−3U ml−1. Only Na+‐K+‐ATPase activity located in the renal medullary thick ascending limb

ISSN:0263-6484    

DOI:10.1002/cbf.290040104

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to determine firstly whether the isolated enzyme DNA polymerase α, which functions within the DNA replicase system, exhibits different sensitivity against the thiol‐blocking agent 4‐hydroxy‐nonenal (HNE) when adult rat liver and the rapidly dividing Yoshida ascites hepatoma were used as enzyme sources and, secondly, whether the reaction catalysed by DNA polymerase is the most sensitive step of the DNA replicase system of native cells.DNA polymerase α as well as the non‐replicative DNA polymerase β, isolated from both sources, were remarkably similar with regard to their sensitivity against HNE, as indicated by the incorporation of radioactive label from [3H]deoxy‐thymidine‐triphosphate into DNA.The transport of [14C]thymidine through the plasma membrane and the incorporation of this precursor into DNA were studied with neonatal hepatocytes and with hepatoma cells. The incorporation of thymidine was inhibited at lower concentrations of HNE in both cell lines than the transport process and the reaction catalysed by DNA polymerase α. It was concluded that in the DNA replicase system of native liver and hepatoma cells another process different from the reaction catalysed by DNA polymerase α is more

ISSN:0263-6484    

DOI:10.1002/cbf.290040105

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe role of ubiquinone in the Golgi apparatus is still unknown, even if it might be considered as a lipid marker of the Golgi compartment because of its high content in these subcellular fractions.In vivomodulation of ubiquinone with ethanol andin vitropentane extraction show that ubiquinone is not required either for NADH‐ferricyanide reductase, acetaldehyde dehydrogenase activity, or Ca2+and Mg2+stimulated ATPases.Since ubiquinone does not seem to be involved in these enzymic activities in Golgi compartments, other possible functions are discussed, related to a role in membrane fluidity or as a barrier to the propagation of free radical

ISSN:0263-6484    

DOI:10.1002/cbf.290040106

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractArticular cartilage is generally considered to be an homogeneous tissue. It has now been shown that, although different regions of the medial tibial cartilage of the dog have very similar oxidative enzymic activities, each region is heterogeneous with respect to these activities. The conventional histological delineation of this cartilage has been modified, to take into account a narrow band (designated zone 2a), just below the most superficial spindle‐shaped cells, that has higher oxidative enzymic activity than any other. Changes in the activity in this zone might be diluted by the lack of change in other zones if measured by conventional biochemical procedures which could not measure the activities of the different zones separatel

ISSN:0263-6484    

DOI:10.1002/cbf.290040107

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractHuman bone‐derived cells, grown in monolayer culture, were dissociated by incubations with trypsin/EDTA and subjected to thin‐layer counter‐current distribution in a ‘low potential’ aqueous two‐phase system. Two major populations of cells were detected. The number of cells in the second (more hydrophobic) population increased with length of trypsinization and time in culture. Cells allowed to ‘regain’ surface molecules lost by trypsinization did not produce the second population.Cells occupying the second population after a short period of trypsinization had a lower rate of division than peak 1 cells but showed a higher rate of protein synthesis per rate of division than peak 1 cells.These results show that the cells have markedly different sensitivities to trypsin digestion which may be related to cell division rate of growth. The possible relationship between this and osteoblast developmen

ISSN:0263-6484    

DOI:10.1002/cbf.290040108

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe aim of this study was to investigate the possibility of enhancing the yield of tissue plasminogen activator (tPA) from two epithelial cell lines of normal (non‐malignant) derivation grown in tissue culture. The three agents used in this investigation were chosen because of thier proven enhancing effect on analogous cells or products. The anabolic hormone stanozolol was found to have no significant stimulatory effect on these cell lines. A phorbol acetate (12‐O‐tetradecanoylphorbol 13‐acetate) caused a twofold enhancement in tPA yield but the most significant results were obtained with 5‐azacytidine. This agent increased the yield by up to fourfold in small stationary cultures and threefold in large‐scale microcarier cultures. A combination of azacytidine and phorbol acetate did not have an additive effect on total yield but did alter the kinetics of tPA expression with time. Indications were that the maximum yield with these types of potentiating agents was achieved as it could not be increased by using a combination of two diffe

ISSN:0263-6484    

DOI:10.1002/cbf.290040109

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractOxygen uptake by erythrocytes exposed tot‐butyl hydroperoxide (t‐BHP) exhibited an induction period. The rate of oxygen consumption can be reduced by antioxidants and blood plasma. The induction time was not appreciably modified by the antioxidants tested, however, plasma increased it by a factor of two. Thein vivopretreatment with diethyl maleate (0·6 g kg−1) produced increased rates of oxygen uptake without changes in the induction period, while vitamin E (12·5 mg kg−1) elicited lower oxygen consumption rates and longer induction times, compared to those observed in cells from control rats upon addition of the hydroperoxide. These results suggest that the antioxidants tested on thet‐BHP lipid peroxidation in erythrocyte suspensions act as inhibitors and/or retarders of the process. Furthermore, lipid peroxidation induced in these conditions seems to depend upon the haemoglobin status of the cells as oxygen uptake, malondialdehyde production and chemiluminescence were significantly higher in methaemoglobin‐containing cells than in those containing o

ISSN:0263-6484    

DOI:10.1002/cbf.290040110

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe transfer of iron between the maternal and fetal circulations of an isolated perfused lobule of term human placenta was investigated using125I‐labelled or59Fe‐labelled diferric transferrin. There was negligible transplacental transfer of intact transferrin whereas nearly 4 per cent of the added59Fe was transferred into the fetal circulation after 2 h, where it became associated with fetal transferrin. Over 20 per cent of the added59Fe radioactivity was sequestered within the placental tissue during this period, associated with transferrin, ferritin and other uncharacterized molecules. This suggests an important role for an intracellular pool in regulating transfer. The presence of 10 mMchloroquine in the maternal circulation substantially reduced tissue accumulation of59Fe and totally inhibited transfer to the fetus. It is concluded that the initial stages of iron transfer to the fetus involve the internalization of maternal iron‐saturated transferrin bound to membrane receptors by receptor‐mediated endocytosis, which can be inhibited by the drug chloroquine. Subsequently, the transplacental transfer of iron to the fetus does not involve the concommitant movement of tran

ISSN:0263-6484    

DOI:10.1002/cbf.290040111

出版商:John Wiley&Sons, Ltd.    

年代:1986

数据来源: WILEY