bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in the activities of three diagnostic enzymes in the heart of rats following the consumption of diets deficient in zinc and essential fatty acids
Authors: Adisa A. O. , Odutuga A. A. 
Published: July 2007

AbstractChanges in the activities of alkaline phosphatase (ALP), lactate dehydrogenase(LDH) and glutamate dehydrogenase (GDH) in the heart following the consumption of diets deficient in zinc and essential fatty acids (EFA) by rats were investigated. The study was a 2 X 2 factorial design in which rats were fed diets deficient in zinc (5μg/g) or EFA (4% hydrogenated coconut oil) or both. The control diet was adequate in both zinc (100μg/g) and EFA (4% soyabean oil). The experimental diets were fed for forty‐two days after which time the activities of the enzymes were terminally determined in the heart of the rats. The result showed that the activity of ALP was markedly elevated in rats consuming either zinc or EFA deficient diet and slightly in the group deficient in both EFA and zinc. LDH and GDH activities were significantly depressed by EFA only. An interactive effect of zinc and EFA was indicated only for ALP activity. The data indicate a resistance of cardiac tissue to moderate zinc deficiency. However, the effects of EFA were apparent.
Possible role of alteration in pH, but not in ionic strength, in the modulation of Ca2 ‐dependent and diacylglycerol‐induced association of protein kinase C‐α with plasma membrane
Authors: Nishino Noriaki , Sugimoto Isamu , Hashimoto Eikichi 
Published: July 2007

AbstractIn an attempt to elucidate the mechanism of the membrane binding of protein kinase C‐α (PKC‐α), effects of pH and ionic strength were examined on Ca2+‐dependent and diacylglycerol‐induced association of this PKC with rat liver plasma membrane. In the absence of diacylglycerol, the membrane‐bound PKC‐α increased according to the changes in pH from 6 to 8. However, these reactions were not seriously influenced by alterations in ionic strength (0‐240 mM NaCl). In the presence of diacylglycerol, this pH‐modulated binding of PKC‐α to plasma membrane was more effective under lower Ca2+ concentration at pH 8. These results suggest that alkaline pH conditions seem to be important for preferable association of PKC‐α with plasma membrane.
Sequence of electron carriers in the process of methanol oxidation by a new obligate methylotrophic bacterium
Authors: Yang Song Suk , Lee Jung Sup , Kim Young Min , Kim Si Wouk 
Published: July 2007

AbstractFrom pink soluble fractions prepared from cells cultured in a copper‐free medium, active methanol dehydrogenase (MDH) and two soluble c‐type cytochromes (c‐I and c‐II) were purified homogeneously. The green fractions from cells grown on a medium containing 1.0 mg/ℓ of copper had inactive MDH, cytochrome c‐II, and blue copper protein. The amount of copper retained in the blue copper protein increased with cultivation time. The oxidized blue copper protein was similar to the classical type I blue copper proteins since it had the novel absorption peak at 625 nm. However, when the blue protein was reduced with MDH or dithionite, it showed the same spectrum as ferrocytochrome c‐I. The isoelectric points of cytochrome c‐I, blue copper protein and cytochrome c‐II were 9.08, 9.08 and 6.52, respectively. These results suggest that the identity of the purified blue copper protein is cytochrome c‐I, and copper ions bind to the cytochrome as methanol is depleted in the culture medium. In addition, MDH activity was not detected at all in the methanol‐depleted condition. The data suggest that blue copper protein acts as a negative regulator for MDH. The electrons were transferred as follows: MDH → cytochrome c‐II → cytochrome c‐I (blue copper protein). It was also revealed that the initial ‘docking’ of MDH and cytochrome c‐II is accompanied by electrostatic interactions between lysine or arginine residues on the α‐subunit of MDH and carboxyl groups on the cytochrome c‐II.
Interactions of photosensitized tetracycline with serum albumin
Authors: Khan Mateen A. , Muzammil Salman , Musarrat Javed 
Published: July 2007

AbstractInteractions of tetracycline with bovine serum albumin (BSA) were studied by fluorescence quenching and circular dichroism (CD) analysis. The binding isotherm exhibited at least 13 tetracycline binding sites on the albumin molecule. Amongst these, four were found to be high affinity sites and the remainder were loose sites. The Scatchard analysis demonstrated the binding constant and capacity of BSA to be 4.6×106 liters/mole and 3.6, respectively. The CD data revealed a significant decrease in the mean residue ellipticity (MRE), indicating alterations in the protein helicity. A reduction of 20% in the α ‐ helical content of the albumin was noted at higher levels of tetracycline in the presence of Cu (II) ions. Thus the strong in vitro interactions of tetracycline with albumin resulted in eonformational changes in its globular structure and insinuate potential health risk due to possible macromolecular damage, under physiological conditions, from the formation of tetracycline/Cu(II) complexes.
Different sources of acidity in glucose‐elicited extracellular acidification in the yeast Saccharomyces cerevisiae
Authors: Lapathitis Georgios , Kotyk Arnost 
Published: July 2007

AbstractThree wild‐type strains of Saccharomyces cerevisiae, viz. K, Y55 and Σ1278b, two mutants lacking one or both of the putative K+ transporters, trklΔ and trklΔtrk2Δ, and a mutant in the plasma membrane H+‐ATPase, viz. pmal‐105, were compared in their extracellular acidification following addition of glucose and subsequent addition of KCl; in ATPase activity in purified plasma membranes; and in respiration on glucose. The glucose‐induced acidification was the greater the higher the respiratory quotient, i.e. the higher the anaerobic metabolism. A markedly lower acidification was found in the ATPase‐deficient pmal‐105 strain but also in the TRK‐deficient double mutant. The acidification pattern after addition of KCl corresponds to expectations in the TRK mutants; however, a similarly decreased acid production was found in the ATPase‐deficient mutant pmal‐105. The highest rate of ATP hydrolysis in vitro was found with the trklΔtrk2Δ mutant where glucose‐, as well as KCl‐induced acidification were lowest. Likewise, the pmal‐105 mutant with extremely low acidification showed only a minutely lower ATP hydrolysis than did its parent Y55 strain. Apparently, several different sources of acidity are involved in the glucose‐induced acidification (including extrusion of organic acids); in fact, contrary to the general belief, the H+‐ATPase may play a minor role in this process in some strains.
Evaluation of 9‐cis retinoic acid for a new remedy of human retinoblastoma
Authors: Tsukamoto Hidetoshi , Kurokawa Tomonori , Hirata Kohji , Ishibashi Sadahiko , Mishima Hiromu K. 
Published: July 2007

AbstractWe investigated the effect of two isomers of retinoic acid (RA), all‐trans RA and 9‐cis RA, on the proliferation of Y79 human retinoblastoma cells. The two isomers inhibited the cell proliferation in a concentration‐dependent manner. The IC50 for this inhibition by all‐trans RA and 9‐cis RA was 1.50 and 0.15 μM, respectively. The inhibitory effect of 9‐cis RA on Y79 cell growth was observed within 24 hr, thereafter the cell number was gradually decreased. In contrast, no inhibition by all‐trans RA of Y79 cell growth was observed within 24 hr, thereafter the cell number was slightly increased. In these cases, the cell viability at 4 days after the addition of 9‐cis RA and all‐trans RA was more than 90 % and 95 %, respectively. These results indicate that the two RA inhibit the proliferation of Y79 human retinoblastoma cells without inducing the cell death and that the effect of 9‐cis RA on the inhibition of Y79 cell growth is much greater than that of all‐trans RA.
Sphingosine induces phospholipase D and mitogen activated protein kinase in vascular smooth muscle cells
Authors: Taher Mohiuddin M. , Abd‐Elfattah Anwar S. , Sholley Milton M. 
Published: July 2007

AbstractThe enzymes phospholipase D and diacylglycerol kinase generate phosphatidic acid which is considered to be a mitogen. Here we report that sphingosine produced a significant amount of phosphatidic acid in vascular smooth muscle cells from the rat aorta. The diacylglycerol kinase inhibitor R59 949 partially depressed sphingosine induced phosphatidic acid formation, suggesting that activation of phospholipase C and diacylglycerol kinase can not account for the bulk of phosphatidic acid produced and that additional pathways such as phospholipase D may contribute to this. Further, we have shown that phosphatidylethanol was produced by sphingosine when vascular smooth muscle cells were stimulated in the presence of ethanol. Finally, as previously shown for other cell types, sphingosine stimulated mitogen‐activated protein kinase in vascular smooth muscle cells.
Effects of prostaglandins and nitric oxide on rat macrophage lipid metabolism in culture: implications for arterial wall‐leukocyte interplay in atherosclerosis
Authors: Senna S. M. , Moraes R. B. , Bravo M. F. R. , Oliveira R. R. , Miotto G. C. , Vidor A. C. , Belló‐Klein A. , Irigoyen M. C. C. , Belló A. A. , Curi R. , de Bittencourt P.I. Homem 
Published: July 2007

AbstractMacrophages/foam cells have a pivotal role in atherogenesis although little is known about the way lipid imbalance, a hallmark of atherosclerosis, leads to lipid accumulation in these cells. Modified low‐density lipoproteins are associated with macrophage lipid dysfunction in atherosclerosis, but a possible role for altered lipogenesis leading to lipid accumulation remains to be elucidated. Since endothelium‐derived nitric oxide (NO) and prostaglandins (PGs) are physiological autacoids whose production may be impaired in atherosclerosis, the effects of these mediators on de novo lipid synthesis in 24‐h cultured rat peritoneal macrophages is investigated. In resident (unstimulated) cells, 1 μM PGE2 and the stable analog of PGI2 carbaprostacyclin (cPGI2, 1 μM) deviated the overall [1‐14C]acetate from incorporation into cholesterol, free fatty acids and triacylglycerols favoring the formation of phospholipids. In inflammatory (thioglycollate‐elicited) macrophages, these eicosanoids likewise reduced tac‐incorporations into all the lipid fractions tested. Also, cPGI2 and PGE2 reduced [4‐14C]cholesterol uptake from inflammatory cells but did not interfere in 14C‐cholesterol export. The PGE2‐derivative PGA2 (10‐20 μM) reduced 14C‐incorporations into all the lipids in resident cells while it enhanced phospholipid synthesis by up to 129% at the expense of reduced incorporations into the other test lipids. The NO donor S‐nitroso‐N‐acetylpenicillamine (SNAP, 1‐10 μM), when added to macrophages in the presence of superoxide dismutase (SOD, to avoid the reaction of superoxide with NO), significantly reduced lipogenesis especially in inflammatory cells. These findings suggest that endothelium‐derived NO and PGs may be associated with macrophage lipid accumulation by modulating lipogenesis and cholesterol uptake within these ceils.
Identification and partial characterization of three calcium‐ and zinc‐independent gelatinases constitutively present in human circulation
Authors: Makowski Gregory S. , Ramsby Melinda L. 
Published: July 2007

AbstractThree constitutive gelatinases in human plasma were identified and characterized relative to known matrix metalloproteinase (MMP) gelatinases: MMP‐2 (fibroblast 72‐kDa) and MMP‐9 (neutrophil 92‐, 130‐, and 225‐kDa). Substrate gel electrophoresis (gelatin zymography) revealed an apparent Mw of 78‐, 82‐, and 89‐ kDa for these gelatinases. Densitometry revealed that MMP‐9 and MMP‐2 were highly calcium sensitive requiring 50‐150 μM and 500 μM calcium for half‐maximal activity, respectively. Of the new gelatinases, only the 89‐kDa form demonstrated slight calcium activation. The three gelatinases were unaffected by known MMP inhibitors: EDTA (5 mM), 1,10‐phenanthroline (2 mM), and pepstatin (18 μM). Serine and thiol protease inhibitors (leupeptin, aprotinin, PMSF, TLCK, TPCK, antichymostatin, antipain) were also ineffective. Solution‐phase IEF revealed that the 78‐ and 82‐kDa forms focused at neutral pl 6.72‐7.95 whereas the 89‐kDa focused at an acidic pI 4.89‐5.18 (similar to neutrophil and fibroblast forms). The data indicate that these gelatinases are not MMPs or partially activated MMPs. Their role in normal and pathological conditions is not known.
Differences in ethidium bromide and 4′‐6‐diamidino‐2‐phenylindole staining profiles with regard to DNA fragmentation during apoptosis
Authors: Shono Masayuki , Shimizu Ichiro , Omoya Toshihiro , Hiasa Aya , Honda Hirohito , Tomita Yumiko , Ito Susumu 
Published: July 2007

AbstractTo simply and directly evaluate DNA fragmentation during apoptosis induced in mouse cultured hepatocytes by an anti‐Fas antibody, we examined the fluorescence intensity in cell nuclei stained with ethidium bromide and 4′‐6‐diamidino‐2‐phenyhndole by optiphoto fluorescence microscopy. The intensity of the former staining for the nuclear DNA of apoptotic cells was clearly decreased compared to that of non‐apoptotic cells, whereas no difference in the fluorescence intensity for the latter stain between the apoptotic and non‐apoptotic groups was observed. Thus, the use of optiphoto fluorescence microscopy, in conjunction with both stains, constitutes a useful tool for the evaluation of apoptotic DNA fragmentation.
The shortening of the N‐terminus of myosin essential light chain A1 influences the interaction of heavy meromyosin with actin
Authors: Efimova Natalya N. , Stępkowski Dariusz , Nieznanska Hanna , Borovikov Yurii S. 
Published: July 2007

AbstractThe effects resulting from the removal of the N‐terminus of heavy meromyosin (HMM) A1 light chain by papain digestion are investigated. The fluorometry of TRITC‐phalloidin labelled actin in ghost fibers is used as a tool for sensing conformational changes of rigor complex of phosphorylated and dephosphorylated HMM with actin filament. The experiments were performed both under conditions assuring saturation of RLC with magnesium cation (4 mM EGTA) or calcium cation (0.1 mM CaCl2), and in constant presence of 1 mM magnesium chloride. HMM native and with A1 shortened from the N‐terminus is used. As it was observed previously rigor complex of actin filament and native HMM shows sensitivity to the kind of cation saturating RLC and to the phosphorylation status of RLC. In particular, the sin2θ parameter of actin bound rhodamine‐phalloidin fluorescence polarization representing roughly the flexibility of actin filament HMM complex changes significantly with the changes of RLC phosphorylation and cation saturation. Removal of the N‐terminus of A1 reduces this sensitivity to cation and phosphorylation both in the case of dephosphorylated and phosphorylated HMM. Our results suggest that the N‐terminus of A1 plays significant role in the rigor interaction of myosin heads with actin and is involved in modulatory function of RLC in this interaction.
Complementation of the growth defect of an RNPA49 mutant of Escherichia coli by overexpression of arginine tRNACCG
Authors: Kim Myung Soon , Park Bo Hyun , Kim Semi , Lee Young Jae , Chung Jae Hoon , Lee Younghoon 
Published: July 2007

AbstractWe previously found that overexpression of arginine tRNACCG from Brevibacterium albidum complements the rnpA49 mutation, which is responsible for the thermosensitivity of Escherichia coli RNase P function. In this present work, we show that the E. coli homologue tRNA also complements the same mutation, but other tRNAs do not. These results suggest that the rnpA49 mutation causes a major cellular defect in an RNase P reaction to generate the mature arginine tRNACCG.
The age‐associated decrease in the amount of amplifiable full‐length mitochondrial DNA in human skeletal muscle
Authors: Kovalenko Sergey A. , Kopsidas George , Islam Mohammed M. , Heffernan Damien , Fitzpatrick Jennifer , Caragounis Aphrodite , Gingold Elliot , Linnane Anthony W. 
Published: July 2007

AbstractThere has been a continuous evolution in our concept [1] that mtDNA undergoes a range of mutations with age and that such alterations lead to a decline in mitochondrial bioenergy capacity. Here we report that a wide range of deletion mutations accumulate with age and the amount of full‐length mtDNA (FLmtDNA) amplifiable by extra‐long PCR (XL‐PCR) markedly decreases with age. An analysis of single human quadriceps muscle fibres reveals a close correlation between the decrease in FLmtDNA and the decline in cytochrome c oxidase activity, an exemplifier of mitochondrial bioenergy. However, Southern blotting analysis of unamplified genomic DNA shows that there is little decrease in FLmtDNA in aged quadriceps. The results are interpreted to indicate that while there is little change in the total mtDNA with age, nonetheless a significant proportion of this mtDNA is extensively damaged such that it cannot be amplified by XL‐PCR. The amplifiable FLmtDNA, which putatively represents the functional component of the mtDNA, decreases markedly with age.
Electron paramagnetic resonance studies of membrane fluidity in ozone‐treated erythrocytes and liposomes
Authors: Wróbel Anna , Gomułkiewicz Jan 
Published: July 2007

AbstractDoxyl stearate spin probes which differed in the attachment of the nitroxide free radical to the fatty acid have been used to study membrane fluidity in ozone‐treated bovine erythrocytes and liposomes. Analysis of EPR spectra of spin labels incorporated into lipid bilayer of the erythrocyte membranes indicates an increase in the mobility and decrease in the order of membrane lipids. In isolated erythrocyte membranes (ghosts) the most significant changes were observed for 16‐doxylstearic acid. In intact erythrocytes statistically significant were differences for 5‐doxylstearic acid. The effect of ozone on liposomes prepared from a lipid extract of erythrocyte lipids was marked in the membrane microenvironment sampled by all spin probes. Ozone apparently leads to alterations of membrane dynamics and structure but does not cause increased rigidity of the membrane.
Steroid sulfatase activity in leukocytes: a comparative study in 45,X; 46,Xi(Xq) and carriers of steroid sulfatase deficiency
Authors: Miranda‐Duarte Antonio , Valdés‐Flores Margarita , Miranda‐Zamora Rodrigo , Díaz‐Zagoya Juan C. , Kofman‐Alfaro Susana H. , Cuevas‐Covarrubias Sergio A. 
Published: July 2007

AbstractThe enzyme steroid sulfatase (STS) hydrolyses 3‐beta‐hydroxysteroid sulfates. The female‐male STS activity ratio is 1.04‐1.7:1 in several cell lines in adults and reaches 2…n1 in prepubertal subjects. In fibroblasts, STS values in X‐chromosome abnormalities show a partial positive correlation according to the number of X‐chromosomes. X‐linked ichthyosis (XLI) carriers, with only one copy of the STS gene, present lower STS levels than normal controls. This study analyzes the STS activity in leukocytes of 46,Xi(Xq); 45,X; XLI carriers and normal controls using 7‐[3H]‐dehydroepiandrosterone sulfate as substrate. X‐monosomy (1.07±0.18 pmol/mg protein/h), Xq isochromosome (1.02±0.12 pmol/mg protein/h) and normal females (1.03±0.11 pmol/mg protein/h) had similar STS values (p>0.05). XLI‐carriers and males showed the lowest STS levels (0.34±0.04 pmol/mg protein/h, p<0.001 and 0.82±0.14 pmol/mg protein/h, p<0.05, respectively). Female‐male STS activity ratio in leukocytes was 1.3…n1. These data indicate that a complex mechanism regulates the STS expression depending on each type of cell line.
Characterization of the carboxyl terminal‐truncated endothelin B receptor coexpressed with G protein‐coupled receptor kinase 2
Authors: Shibasaki Tadao , Moroi Kayoko , Nishiyama Mariko , Zhou Jing , Sakamoto Aiji , Masaki Tomoh , Ito Kazumitsu , Haga Tatsuya , Kimura Sadao 
Published: July 2007

AbstractThe role of phosphorylation of the C‐terminal tail of endothelin B receptor (ETbR) in agonist‐induced desensitization was investigated, using a mutant lacking C‐terminal 40 amino acids (Δ40 ETbR). In cells expressing the wild type or Δ40 ETbR, ET‐1 caused rapid desensitization of calcium responses. The wild type ETbR was phosphorylated by biotinylated ET‐1, and the phosphorylation was markedly enhanced by coexpression with G protein‐coupled receptor kinase 2 (GRK2). However, Δ40 ETbR was not phosphorylated regardless of coexpression with GRK2. On the other hand, ET‐1‐induced IP3 formation in these cells was decreased by coexpression with GRK2 or catalytically inactive Lys220Arg GRK2 to the similar extent. The present study demonstrates the presence of phosphorylation‐independent desensitization mechanism in Δ40 ETbR and suggests that GRK2 might play a role other than that as a kinase.
Characterization of the human CR1 gene promoter
Authors: Kim Jae Hyun , Lee Sooyeon , Choe Soo Young 
Published: July 2007

AbstractThe human CR1 is a single chain membrane glycoprotein that is a member of the group of regulators of the complement activation system. In order to clarify the regulatory mechanisms of human CR1 gene expression, the 5′‐flanking region of the human CR1 gene was isolated and its promoter was characterized. The CR1 expression was found to be transcriptionally up‐regulated in HL60 cells by stimulation with DMSO. The cloned CR1 gene promoter was sequenced and computer analyzed. The potential promoter region lacks a distinct TATA box sequence. The transcription initiation site was determined by primer extension and several possible regulatory elements for transcription were found in the promoter region.
Kinetic properties of ATP‐dependent phosphofructokinase from grapefruit juice sacs: effect of tca cycle intermediates
Authors: Van Praag Esther , Zehavi Uri , Goren Raphael 
Published: July 2007

AbstractGrapefruit juice sac ATP‐PFK was studied kinetically for its substrates ATP and Fru‐6‐P at pH = 7.5. The Km for ATP is equal to 39.8 ± 4.6 μM. ATP becomes inhibitory at concentrations above 80 μM. The Km for ATP is not affected by the addition of citrate (10 mM). For Fru‐6‐P, the saturation curve is sigmoidal, with an S0.5 equal to 0.17 ± 0.03 mM, in the presence of Mg++ (2.5 mM) and ATP (1 mM). ATP‐PFK shows a negative cooperativity at lower concentrations of Fru‐6‐P (h = 0.5), while higher concentrations of the substrate induce a positive cooperation (h = 1.5). The presence of citrate affects the S0.5 affinity value, but not the Vmax. The presence of citrate (10 mM) removes the cooperative effect at higher concentrations of the substrate, as h = 1.0. A theoretical Ki for citrate was calculated and equals 1.30 mM.
Synthetic insulin fragment with insulin‐like biological activity
Authors: Prozorovskiy V. N. , Maksimova E. M. , Alekseeva A. E. , Grebenschikova O. G. , Abakumova O.Yu. , Kutsenko N. G. , Ivanov A. S. , Kniazhev V. N. , Archakov A. I. 
Published: July 2007

AbstractAn insulin fragment, representing the C‐terminal functionally important site of its molecule and responsible for receptor binding, was synthesized. The fragment consists of two peptides: a dipeptide (A 20‐21) and an octapeptide (B 19‐26), linked with a disulfide bond (A20‐B19). The biological activity of the newly synthesized fragment relative to insulin was assayed for the influence on glycogenesis and for the ability to stimulate glucose uptake. Comparative tests for the biological activity of the synthesized fragment and of the intact hormone allowed us to conclude that the fragment has insulin‐like properties.