bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorimetry of mitochondria in cells vitally stained with DASPMI or rhodamine 6 GO
Authors: Bereiter‐Hahn Jürgen , Seipel Karl‐Heinz , Vöth Monika , Ploem Johan S. 
Published: May 2005

AbstractThe fluorescent dyes DASPMI and rhodamine 6 GO specifically stain mitochondria in living cells. Dye concentrations from 10−8 to 5 × 10−6 mole l−1 can be used. Excitation and emission spectra, and quantum efficiency of DASPMI depend on solvent characteristics. Spectra of mitochondria in living cells correspond to those in phospholipids (excitation around 470 nm, emission 560–570 nm). Fluorescence intensity of DASPMI is a measure for the energization of mitochondria, as revealed by in vitro studies. In living cells uptake of the dye is strongly influenced by inhibitors of oxidative phosphorylation (i.e. by oligomycin, FCCP). Distribution of fluorescence intensity indicates an intracellular gradient in energy load of endothelial cells. Single mitochondria exhibit oscillations in fluorescence. Mitochondria loaded with DASPMI release the dye suddenly into the cytoplasm on treatment with FCCP. Cyanide and antimycin however, do not diminish fluorescence in vivo under optimal nutritional conditions, while they do so in mitochondrial suspension, indicating different mitochondrial behaviour in vivo and in suspension.
Glycosaminoglycan: Cell interactions; their role in lipoprotein lipase secretion from isolated cardiac muscle cells
Authors: Cryer Anthony , Wusteman Frederick S. , Casey Jill J. 
Published: May 2005

AbstractWhen cardiac muscle cells from mature rats were incubated in vitro in the presence of heparin (8.7 nmole ml−1) lipoprotein lipase activity appeared in the incubation medium. The intracellular activity of the enzyme remained unchanged. Other glycosaminoglycans (heparan sulphate, dermatan sulphate, keratan sulphate and chrondroitin 6‐sulphate) at the same or higher concentrations were totally ineffective in producing any enzyme redistribution between cells and medium. The release seen in the presence of heparin was blocked by the presence of cycloheximide. Cycloheximide by contrast had no effect on the release observed in the presence of dexamethasone, The action of endogenous glycosaminoglycans are unlikely therefore to have a significant role to play in the movement of lipoprotein lipase in heart tissue in vivo.
Drug—membrane interactions: Silymarin, silibyn and microsomal membranes
Authors: Parasassi T. , Martellucci A. , Conti F. , Messina B. 
Published: May 2005

AbstractSilymarin and silibyn are extracted from the seeds of Silybum marianum and used as a liver protectant because of their free radical scavenging. When incorporated into rabbit liver microsomes they cause a small decrease in the flourescence anisotropy of 1,6‐diphenyl‐1,3,5‐hexatrine (DPH) but not of 1‐anilinononaphthalene‐8‐sulphonic acid (ANS), incorporated into the membranes. They do, however, reduce the fluorescence intensity of incorporated ANS without changing the wavelength of maximum intensity. These observations suggest that the drugs are incorporated into the hydrophobic–hydrophilic interface of the microsomal bilayer and perturb the structure by influencing the packing of the acyl chains.
Stimulation of rat renal Na+, K+‐ATPase activity by thyroid hormones
Authors: Pippard Corinna , Baylis P. H. 
Published: May 2005

AbstractThe effect of thyroid hormones (T4, T3 and reverse T3) on rat renal Na+, K+‐ATPase activity was investigated by a cytochemical technique. T3 caused stimulation of Na+, K+‐ATPase activity in the renal medulla but not in the renal cortex. There was a peak in enzyme activity after cultured renal segments had been exposed to T3 for 11 min and this time of maximal stimulation did not vary with the concentration of T3. A rectilinear response in Na+, K+‐ATPase activity was observed over T3 concentration range 10 pmol l−1 to 100 nmol l−1; at higher T3 concentrations, Na+,K+‐ATPase activity was inhibited. The enzyme response was totally blocked by specific T3 antiserum. Addition of T4 and reverse T3 (100 fmol l−1 − 1 mmol l−1) failed to stimulate Na+,K+‐ATPase activity in any part of the kidney. Plasma (neat and diluted 1:10) stimulated the enzyme in parallel with the dose response curve and the stimulatory effect was abolished by prior addition of specific T3 antiserum.
Polyamines in Entamoeba invadens
Authors: Chayen A. , Mirelman D. , Chayen R. 
Published: May 2005

AbstractThe polyamine content of Entamoeba was measured by a procedure that involved benzoylation followed by high performance liquid chromatography (h.p.l.c.). A high concentration of putrescine and significant amounts of spermidine and spermine were found in actively growing trophozoites and in the cyst forms of the organism. In contrast, trophozoites in stationary phase had greatly reduced amounts of putrescine and exhibited peaks in h.p.l.c., possibly indicative of acetylated polyamines. α‐D,L‐difluoromethylornithine (DFMO) lowered the concentration of polyamines in growing trophozoites, but did not inhibit the degree of proliferation. There is evidence for pathways of polyamine biosynthesis in Entamoeba other than through ornithine decarboxylase (ODC).
Immunofluorescent staining method for use with monoclonal antibodies
Authors: Costanzo Catherine , Raza Azra 
Published: May 2005

AbstractThis note describes an immunofluorescent staining method for cells in the S‐phase which have been allowed to take up bromodeoxyuridine into their DNA in place of thymine. The technique involves the use of fluorescinated monoclonal antibodies against bromodeoxyuridine and allows rapid and accurate estimation of cells in the S‐phase, the technique does not require interpretation by skilled technicians.
Comparative subcellular fractionation of control and cold‐adapted rat brown and white adipose tissue with special reference to peroxisomal and mitochondrial distributions
Authors: Karmali Anis , Montague David J. , Peters Timothy J. , Holloway Brian R. 
Published: May 2005

AbstractA new technique for single‐step subcellular fractionation of adipose tissue homogenates by analytical sucrose density gradient centrifugation in a vertical pocket reorientating rotor is described. The density gradient distributions of mitochondrial and peroxisomal marker enzymes in brown and white adipose tissue of control and cold exposed rats are compared. The equilibrium density of brown fat mitochondria was found to be significantly increased compared with white fat mitochondria. GDP binding activity was localized solely to the mitochondria in both control and cold‐adapted brown adipose tissue. Brown and white fat mitochondria fractions were isolated by differential centrifugation and the specific activities of various enzymes in the homogenate and mitochondrial preparations determined. The specific activity of creatine kinase in brown adipose tissue was found to be ten‐fold higher than in white fat and subcellular fractionation studies showed the activity to have an exclusively cytosolic distribution in both tissues. GDP binding activity and some of the mitochondrial enzymes showed, in brown adipose, a striking increase in total activity in cold adapted rats compared to control animals. For some enzyme activities there was a small increase when expressed per mg tissue or per mg mitochondrial protein. When expressed per mg DNA i.e. per cell, there was a reduced specific activity of the mitochondrial and peroxisomal enzymes in both brown and white adipose tissue on cold adaptation.
Adenine nucleotides in thrombocytes of birds
Authors: Wachowicz Barbara 
Published: May 2005

AbstractAnalysis of free nucleotide composition of both avian thrombocytes and pig platelets showed quantitative differences in the level of adenine nucleotides. 3H‐adenine taken up by turkey thrombocytes was metabolized mainly to adenine nucleotides was not released after thrombin action. Thrombin liberated non‐radioactive adenine nucleotides (18.2 ± 1.5 %, 20.6 ± 1.9%) of the total, probably localized in a storage pool. Malonyldialdehyhyde (MDA) production due to thrombin was observed in both platelets and thrombocytes.
Shape change of human erythrocytes induced by phosphatidylcholine and lysophosphatidylcholine species with various acyl chain lengths
Authors: Fujii Tatsuzo , Tamura Akira 
Published: May 2005

AbstractIntact human erythrocytes were treated, under non‐haemolytic conditions at 37°C, with synthetic phosphatidylcholine which has homologous, saturated acyl chains of 8 ∼ 18 even‐numbered carbon atoms (C8 ∼ C18‐PC) or with lysophosphatidylcholine which has a saturated acyl chain of 8 ∼ 18 carbon atoms (C8 ∼ C18‐lysoPC). The C8 ∼ C14‐PC and C12 ∼ C18‐lysoPC species were rapidly incorporated into the erythrocytes and induced a shape change of the crenation (echinocyte formation) type. The site of the incorporation was found to be most probably on the outer leaflet of the membrane lipid bilayer. The extent of the shape change was dependent on the amount of each lipid incorporated. When the same amount of a PC or lysoPC species was incorporated into the membrane, about the same extent of crenation was induced, independent of acyl chain length. However, C16‐PC, C18‐PC, C8‐lysoPC and C10‐lysoPC, which were not incorporated into the erythrocytes, did not induce any shape change. It is therefore suggested that the hydrophobic moiety of these amphiphilic lipids may greatly contribute to their transfer from the outer medium into the erythrocyte membrane, but do not influence so much the perturbation of the membrane lipid bilayer which may be responsible for induction of the shape change.
Iodide accumulation into thyroid golgi vesicles
Authors: Bastiani P. , Rognoni J. B. 
Published: May 2005

AbstractPig thyroid Golgi vesicles incubated in a suitable medium were able to concentrate iodide from the medium. This trapping required the integrity of the vesicles, was time‐ and temperature‐dependent, and was inhibited by a competitive inhibitor of iodide active transport (perchlorate), suggesting a facilitated transport mechanism.
Phospholipids in plant and animal chromatin
Authors: Viola‐Magni M. P. , Gahan P. B. , Pacy J. 
Published: May 2005

AbstractIsolated hepatic nuclei and hepatic chromatin have been analysed for their DNA, RNA, protein and phospholipid content. The protein/DNA ratio is 3 for nuclei and 1·95 for chromation extracted from Triton X‐100 treated nuclei. The phospholipids, (2·36 ± 0·91 (S.D.) per cent of the total nuclear material), are lost during the chromatin preparation mainly during the Triton X‐100 washings of the nuclei. Nevertheless, 10 per cent of the total nuclear phospholipids and fatty acid composition. Thus, the chromatin‐associated phospholipid cannot be attributed simply to contaminating nuclear membrane.This is supported by the autoradiographic study of semi‐thin sections of interphase nuclei from root apices of Vicia faba in which [3H] ethanolamine is clearly localized in the chromatin and nucleolar regions of the nuclei.
Partial immunochemical identity between (Na+ + K+)‐atpase and a membrane component extractable with chloroform: Methanol
Authors: Addis John S. , Tenbarge Karen M. , Barrnett Russell J. 
Published: May 2005

AbstractAn IgG fraction prepared from an antiserum against a holoenzyme preparation of (Na+ + K+)‐ATPase precipitated a single antigen when samples of holoenzyme were subjected to crossed immunoelectrophoresis but precipitated an additional, immunochemically‐related antigen when a plasma membrane‐enriched fraction was subjected to crossed immunoelectrophoresis under the same conditions. The immunochemically‐related antigen could be extracted from the plasma membrane fraction with CHCl3:CH3OH.
Role of transferrin in metal uptake by human lymphoblasts in vitro
Authors: Planas‐Bohne Felicitas , Taylor David M. , Duffield John R. 
Published: May 2005

AbstractThe uptake and binding of 59Fe, 67Ga and 239Pu complexed with citrate of transferrin (Tf) and of 125I‐labelled Fe–Tf by human lymphoblasts (WI‐L2 cells) have been studied. Uptake kinetics of 59Fe–Tf and [125I]‐Tf point to internalization by receptor mediated endocytosis. 67Ga binding and uptake is always less. This may be explained by a lower affinity of Ga‐complexes for the cell surface. Factors which influence Fe uptake have a similar effect on Ga. 239Pu uptake and binding, however, are different, especially in that Tf does not stimulate 239Pu uptake and may actually decrease it.
Characterization of insulin receptors in isolated epithelial cells of rat ventral prostate: Effect of fasting
Authors: Carmena M. J. , Fernandez‐Moreno M. D. , Prieto J. C. 
Published: May 2005

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−1 protein), and another class of receptors with low affinity (Kd = 0·29 μM) and high binding capacity (1·43 pmol mg−1 protein). 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 prostatic epithelium.
Effects of antioxidants and haemoglobin status on the t‐butyl hydroperoxide‐induced oxygen uptake by red blood cells
Authors: Lissi E. , Franz R. , Cabezas J. , Fernández V. , Videla L. A. 
Published: May 2005

AbstractOxygen uptake by erythrocytes exposed to t‐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. The in vivo pretreatment 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 the t‐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 oxyhaemoglobin.
Flow cytometric determination of cell cycle phase‐specific changes in cellular phosphatase and glycosidase activities
Authors: Britten R. A. , Dyson J. E. D. 
Published: May 2005

AbstractThe activities of two phosphatases (E. C. 3.1.3.1 and 3.1.4.1) and four glycosidases (E.C. 3.2.1.21, 3.2.1.30, 3.2.1.31 and 3.2.1.51) were measured by fluorescence spectrophotometry, and flow cytometry, in mitogenstimulated lymphocytes, and in cultures of Molt‐4‐F and F‐89 cell lines, syncronized by hydroxyurea or thymidine.All enzymes were active throughout the cycle but the activities of three enzymes were elevated at specific points in the cycle, alkaline phosphatase activity increased at G2 + M/G1 boundary and in early S‐phase, the activity of β‐L fucosidase was elevated in G1 and late S‐phase. Orthophosphate diesterase activity was elevated at the G1/S boundary, and during G2 + M. The increase in β‐L fucosidase activity was due to an increased number of cells showing activity, whilst the increase in orthophosphate diesterase activity was attributable to an increase in cellular enzyme activity.Only the activities of orthophosphate diesterase and β‐L fucosidase were measurable by flow cytometry, alkaline phosphatase activity was mainly extracellular, and therefore not detectable by flow cytometric methods employed.
Calcium transport from blood into the bile in normal and regenerating rat liver
Authors: Bachs Oriol , Soriano Montserrat , Piñol M. Rosa , Serratosa Joan , Enrich Carlos 
Published: May 2005

AbstractWe have studied calcium movement from blood into the bile by injecting 45Ca2+ intravenously and measuring the radioactivity appearing in the bile. 45Ca2+ started to appear in the bile at 3 min and maximum values were observed at 5 min after its administration. The amount of calcium secreted into the bile was proportional to the blood calcium concentration indicating that the main pathway involved in calcium movement behaved as a non‐saturable system.We have also studied the 45Ca2+ circulation from blood into the bile in rats subjected to a partial hepatectomy. Thereafter, the calcium transported into the bile per gram of liver increased by about 50 per cent. Since bile flow behaved in a similar way, the biliar calcium concentration remained unmodified after hepatectomy.Determination of the activities of the Ca2+ transporting systems in isolated plasma membrane fractions from regenerating livers showed no modification in these activities suggesting that the elevation in calcium movement observed after hepatectomy is not due to an increase in the circulation of Ca2+ through the transhepatocyte pathway, an observation compatible with the absence of saturation in the transport.
Lipases operative at the fat cell surface: Attempt at an integrated approach
Authors: Verine Alain , Boyer Jean 
Published: May 2005

AbstractExtracellular acylglycerols are hydrolysed by lipases active at the surface of intact fat cells isolated from rat or human adipose tissue. During short‐term incubation, rat fat cells hydrolyse di‐[3H]oleyl‐[14C]glycerol at a rate of 70 ± 7·7 mU/106 cells (means ± S.E.) versus 440 ± 62 mU/106 cells for the hydrolysis of mono‐[3H]oleylglycerol; these relatively high lipolytic potencies may serve, among other functions, to counteract the cytolytic effect of both esters. Reaction rates with both substrates are unchanged by addition of various apolipoproteins C and by the nutritional state of the animals. Fat cells incorporate 15–20 per cent of the total [3H]‐oleic chains liberated by hydrolysis, with no correlation between uptake and hydrolysis rates. [3H]‐oleic chains in cell lipids are found mainly as diacylglycerol (15 per cent) and triacylglycerol (80 per cent). Both lipolytic processes differ from the hydrolysis of trioleyglycerol by cell‐bound lipoprotein lipase, which occurs at lower rates (6·5 ± 0·6 mU/106 cells) and depends on apolipoprotein C‐II and nutritional state of the animals. The results support the accepted view that lipoprotein lipase and monoacylglycerol lipase are distinct enzymes. Differences between lipoprotein lipase and diacylglycerol lipase activities raise the possibility of different catalytic entities. In conclusion, isolated fat cells in suspension hydrolyse and incorporate lipids. This model should approximate physiological conditions more closely than the use of lipases in the free state.
Prolyl hydroxylase activity as an index of liver damage induced by ethanol
Authors: Bańkowski Edward , Pawlicka Elżbieta , Jodczyk Kazimierz J. 
Published: May 2005

AbstractIt was found that chronic intoxication of rats with ethanol results in an increase of prolyl hydroxylase activity in liver and serum of the experimental animals. The increase of enzyme activity precedes the morphological symptoms of liver damage. The possibility arises that the assay of prolyl hydroxylase in serum or in liver biopsy samples could be useful for the diagnosis of the tendency of some individuals to develop liver cirrhosis induced by ethanol.
Introduction and metabolism of pentose and hexose phosphates in permeabilized morris hepatoma 5123TC cells
Authors: Arora Krishan K. , Williams John F. 
Published: May 2005

AbstractMetabolism of arabinose 5‐P, ribose 5‐P and glucose 6‐P in permeabilized and resealed Morris hepatoma 5123TC cells was investigated by measuring the contribution of these compounds to nucleic acid biosynthesis. The level of [14C]‐arabinose (non‐phosphorylated) incorporation into nucleic acids was slight, presumably due to the low activity of the transport system or the absence or low activity of a specific ‘kinase’ enzyme. The permeabilizing procedure involved the brief treatment of Morris hepatoma 5123TC cells with lysolecithin and resulted in a cell population which was permeable to charged compounds i.e. Sugar phosphates and nucleotides, that otherwise could not cross the plasma membrane. The permeabilized (and resealed cells) retained normal cellular morphology and intactness of specific organelles as judged by the maintenance of functional properties. Following permeabilization, these cells resealed when transferred back to normal growth medium, and continued to divide and increase at the same rates as control non‐permeabilized cell cultures. The permeabilized cells incorporated deoxyribonucleotides ([methyl ‐3H]‐TTP) into DNA at a linear rate of 0·047 nmol per 107 cells min−1, representing 90–100 per cent of the DNA synthesis rate in vivo. The permeabilization technique, when coupled with procedures to establish cell synchrony, permitted the comparative estimate of the contributions of [14C]‐labelled arabinose 5‐P, ribose 5‐P and glucose 6‐P to RNA, DNA, amino acids, CO2, lactate and sugar mono‐ and bisphosphates. The percentage of [14C]‐isotope incorporated into total nucleic acids by these three labelled sugar phosphates were 2·3, 4·9 and 6·3 respectively. Possible reasons for the lower incorporation of 14C from arabinose 5‐P are given. The results are consistent with the proposal that arabinose 5‐P, an intermediate of the L‐type pentose pathway activity of 5123TC cells, was incorporated into nucleic acids by its interconversion with ribulose 5‐P and ribose 5‐P and thus into PRPP. This study represents the first report of sugar phosphate as opposed to free sugar metabolism by tumour cells in culture.
Pyruvate kinase activity and response to allosteric effectors in rat erythrocytes and reticulocytes fractionated by multiple partitioning in aqueous two‐phase systems
Authors: Pinilla Montserrat , Rodriguez‐Horche Paz , Luque Jose 
Published: May 2005

AbstractSpecific activity of pyruvate kinase decreases as the age of rat erythrocytes increases in fractions obtained by counter‐current distribution in dextran‐polyethylene glycol biphasic systems; the enzyme is inhibited by ATP and activated by fructose‐1,6‐bisphosphate at low phosphoenol pyruvate concentrations. Specific activity does not change in fractions from > 95 per cent‐rich reticulocytes (anaemic rats); the enzyme is inhibited by ATP but not activated by fructose‐1,6‐bisphosphate. These results can be explained on the basis of different pyruvate kinase isozymes and suggest that decrease in activity is not affecting regulatory properties during erythrocytes aging.