bluuebunny/crossref_metadata_2025 huggingface dataset:
The urease-catalyzed hydrolyses of some substituted ureas and esters of carbamic acid
Authors: Sundaram P. V. , Laidler K. J.
Published: December 2009

By use of a new technique for the assay of products resulting from hydrolyses catalyzed by urease, the following substituted ureas and esters of carbamic acid have been found to be substrates for urease: methyl-, ethyl-, formyl-, and allylurea, and methyl and ethyl carbamates. The rate–pH profiles have been determined for urea and these substrates, under conditions of enzyme saturation and in the absence of buffer. Variations of rate with substrate concentration have been studied at the optimum pH in each case; approximate Michaelis–Menten kinetics was observed in all cases, but with substrate inhibition for the substituted ureas, not for the carbamates. All of the reactions were inhibited by the NH4+ ions formed.
Liehen substances. IV. Incorporation of pulvinic-14C acids into calycin by the lichen Pseudocyphellaria crocata
Authors: Maass W. S. G.
Published: December 2009

Pulvinic-14C acid, vulpinic-14C acid, and ethyl pulvinate-14C were found to be good precursors of calycin but not of pulvinic dilactone or of pulvinic acid normally present in Ps. crocata. Some of the labeled precursor became bound in acetone-insoluble materials before the radioactive carbon began to accumulate in calycin. Calycin probably arises by hydroxylation of a bound form of pulvinic acid.
Diet and 14CH3-Methionine Incorporation into Liver Phosphatidylcholine Fractions of Male and Female Rats
Authors: Lyman R. L. , Sheehan G. , Tinoco J.
Published: December 2009

An experiment was conducted to see whether diet influenced the incorporation of 14CH3-methionine into liver phosphatidylcholines of male and female rats.Rats of both sexes were fed either a stock diet (Purina Chow), a semipurified diet containing 10% flaxseed oil, or a low methionine diet with or without choline. One hour before killing, 14CH3-methionine was injected into the animals. The distribution of the label in subfractions of liver phosphatidylcholines was then determined.Choline phosphatides of female rats fed chow or flaxseed oil diets had higher specific activities than did those of males. In chow-fed female rats the additional radioactivity appeared mainly in the tetraene phosphatidylcholine fraction. In female rats fed flaxseed oil, the extra label appeared in the tetraene as well as in a pentaene fraction.Therefore, changes in the degree of unsaturation of the species of phosphatidylcholine by dietary modification did not alter total incorporation of the label into liver phosphatidylcholines nor did it influence sex differences in the incorporation even though the distribution of the label within particular species of choline phosphatides was changed.No sex differences in incorporation were evident in the low methionine diet whether it contained choline or not. Choline deficiency did not affect total incorporation of the methyl group nor the proportions of phosphatidylcholine subfractions in the phospholipids, although in males it depressed the amount of hepatic phosphatidylcholine.
Coupling Factor for Photophosphorylation in Bean Etioplasts and Chloroplasts
Authors: Horak A. , Hill R. D.
Published: December 2009

Extracts from either bean chloroplasts or etioplasts stimulate photophosphorylation in partially deficient chloroplast residues. Both extracts contain a latent Ca2+-dependent ATPase but the specific activity of the chloroplast extract is about sevenfold higher. The etioplast ATPase appears to have identical properties to a spinach chloroplast ATPase that has been shown to be a modified coupling factor for photophosphorylation.
RNA Synthesis in Peripheral Nerve in the Chick during Development
Authors: Hu Yu-Wan , Mezei Catherine
Published: December 2009

The pattern of RNA synthesis was investigated in vitro in the sciatic nerve of the chicken. Nerve tissue from 14-day embryos, 17-day embryos, and 3-day chicks was incubated with [5-3H]-uridine for 0.5, 1.5, and 3.5 h. The RNA was isolated from the tissues and the purified preparations were fractionated by zone velocity centrifugation on sucrose gradients.The sedimentation properties of the rapidly labelled RNA changed in the three developmental stages. The proportion of the radioactivity in the light fractions of the RNA (5.8–17.2 S) increased with the age of the animals. In contrast, the specific activities of the heavy species decreased during nerve development. Pulse-chase experiments with unlabelled uridine and actinomycin D demonstrated the metabolic lability of the rapidly labelled RNA. The sedimentation properties of the pulse-labelled RNA of the cerebellum were the same in the three developmental stages.
Aggregation States of a Regulatory Enzyme Complex Catalyzing the Early Steps of Pyrimidine Biosynthesis in Bakers' Yeast
Authors: Lue P. F. , Kaplan J. G.
Published: December 2009

Aspartate transcarbamylase (ATCase) of bakers' yeast has been purified 78-fold from a crude extract of a derepressed diploid strain; its specific activity was more than 300-fold that of a wild-type crude extract. During the last steps of the purification there was a parallel co-purification of carbamylphosphate synthetase (CPSase), and both activities retained full sensitivity to feedback inhibition by UTP; indeed the sensitivity of the ATCase to UTP increased during the purification doubtless due to discard of a feedback-insensitive ATCase subunit. The two enzyme activities co-eluted from gel filtration on Sepharose 6B together with the feedback site. Analytical ultracentrifugation revealed that the material was not homogeneous, showing two major peaks. Sucrose density gradient centrifugation in the presence of UTP, glutamine, and Mg2+ resulted in co-sedimentation of the two activities and the regulatory site, corresponding to a molecular weight of approximately 800 000 daltons. Omission of UTP from the gradient resulted in disappearance of the heavy peak and appearance of a new one, corresponding to a molecular weight of 380 000 and possessing both activities; the CPSase was still highly sensitive to UTP unlike the ATCase which was only slightly sensitive to retroinhibition. Omission of glutamine and Mg2+ from the sucrose density gradient caused a distinct CPSase peak to trail behind the ATCase; again, the CPSase (molecular weight 250 000) retained full sensitivity to feedback inhibition. This, together with genetic data, supports the view that the ura-2 gene which controls ATCase, CPSase, and the regulatory site is a polycistronic operon, coding for the production of two or three polypeptide chains; the CPSase subunit is inactive unless a regulatory site is present, whereas the ATCase subunit (molecular weight 140 000) is highly active but completely insensitive to feedback inhibition.
Effect of Acriflavine and Ethidium Bromide on the Synthesis of RNA of the Peripheral Nerve in the Chick during Development
Authors: Mezei Catherine , Hu Yu-Wan , Aitken Elizabeth
Published: December 2009

The effect of the trypanocidal dyes acriflavine and ethidium bromide on the sedimentation pattern of tritium-labelled RNA of the sciatic nerve of chicks was studied. Tissues from 14-day embryos, 17-day embryos, and 3-day chicks were incubated with [5-3H]uridine in organ culture, in the presence and in the absence of the inhibitors. Acriflavine and especially ethidium bromide caused a selective inhibition of the labelling of the RNA species which sedimented between the 17.2 S and 5.8 S components of the bulk RNA in the older animals. The labelling of the RNA with sedimentation values higher than 17.2 S was not decreased by ethidium bromide during a 1.5 h incubation period, indicating that rRNA, rRNA precursors, or heterogeneous nuclear RNA was not affected by the drug.
Modification of Rat Renal Cortical Chromatin by Aldosterone Treatment
Authors: Trachewsky Daniel , Cheah Anne M.
Published: December 2009

A comparison of the template capacities of purified chromatin from the kidney cortices of control and aldosterone-treated rats, which had been previously bilaterally adrenalectomized, indicated that in the presence of added DNA-dependent RNA polymerase, the capacities of the purified chromatins to act as templates for RNA synthesis were equal 90 min after hormone injection.Since 1.2% of the guanine–cytosine nucleotide pairs of the chromatin from the control rats bound actinomycin-D-14C while 0.6% of the guanine–cytosine nucleotide pairs of the chromatin from the hormone-treated animals did so, it is possible that the physical or chemical state of the chromatin had changed with aldosterone treatment.
The Disulfide Bridge Sequences of a Serine Protease of Wide Specificity from Streptomyces griseus
Authors: Johnson P. , Smillie L. B.
Published: December 2009

The isolation of a Protease from pronase by carboxymethylcellulose and Bio-Rex 70 column chromatography is described. The esterolytic activity of the protease (termed Streptomyces griseus Protease A) towards N-acetyltyrosine ethyl ester was inhibited by diisopropyl fluorophosphate treatment but not by L-(1-tosylamido-2-phenyl) ethyl chloromethyl ketone treatment.When oxidized insulin A and B chains were used as substrates in proteolytic specificity studies, it was found that the protease had a wide specificity, with cleavages at peptide bonds containing the carboxyl group of amino acids which did not have electrophilic or polar substitutions on their β-carbon atoms.Interesting features of the amino acid analyses were that the protease molecule contained four half-cystines, three histidines, and one methionine, but no lysines.The two peptic disulfide bridge peptides in the molecule were isolated by G-25 Sephadex chromatography, and paper electrophoresis and chromatography. Sequence analysis of these peptides indicated that one bridge peptide contained the characteristic "active serine" sequence found in Asp–Ser–Gly serine proteases, whilst the other contained the "active histidine" sequence found in these serine proteases.The "active serine" and "active histidine" sequences appeared to be highly homologous with those of the other bacterial and mammalian serine proteases, particularly with those of the α-lytic protease of Myxobacter 495.
2-Deoxyglucose Transportation Via Passive Diffusion and its Oxidation, Not Phosphorylation to 2-Deoxygluconic Acid by Pseudomonas aeruginosa
Authors: Eagon R. G.
Published: December 2009

The transport and catabolism of 2-deoxyglucose by Pseudomonas aeruginosa were studied. 2-Deoxyglucose was taken up and oxidized by glucose-grown cells at a rate approaching that of the uptake and oxidation of glucose. However, 2-deoxyglucose entered these cells via passive diffusion while glucose entered via an inducible active transport system. 2-Deoxyglucose was oxidized stoichiometrically, presumably by glucose dehydrogenase, to 2-deoxygluconic acid which, in turn, diffused out of the cells. No phosphorylated intermediates were detected. Glucose dehydrogenase was induced by cultivating the cells on glucose. There was suggestive evidence that the membrane-bound glucose dehydrogenase provided energy for the transport of glucose.
Hemoglobin Binding by Enzymatic Fragments of Haptoglobin
Authors: Ofosu F. , Connell G. E.
Published: December 2009

Two fragments, P1 and P2, which were obtained by digestion of haptoglobin by plasmin remained associated in neutral and alkaline buffers, although the electrophoretic and ultracentrifugal behavior of the complex was significantly different from that of native haptoglobin. The P1–P2 complex bound hemoglobin yielding a product indistinguishable at neutral pH from the normal haptoglobin–hemoglobin complex. P2 had no hemoglobin-binding property. There appears to be a weak interaction between Hb and P1 as shown by lowered electrophoretic mobility of P1 in presence of hemoglobin. However, no evidence for a stable complex between P1 and hemoglobin was obtained.
The Incorporation of Ethanolamine and Methionine into Sphingomyelin in Ehrlich Ascites Tumor Cells
Authors: Sinclair Andrew J.
Published: December 2009

Using Ehrlich ascites tumor cells, it was shown that choline-1,2-14C, and also ethanolamine-2-14C and methionine(methyl-3H) were incorporated into sphingomyelin. Further experiments revealed that ethanolamine-2-14C was incorporated into phosphorylethanolamine, cytidine 5′-diphosphate ethanolamine, phosphatidylethanolamine, phosphatidylcholine, cytidine 5′-diphosphate choline, and sphingomyelin, and that methionine(methyl-3H) was incorporated into the three latter compounds. The specific activities of these compounds were found to decrease in the order shown above when the tumor cells were incubated with either ethanolamine or methionine. When microsomal preparations from the tumor cells were incubated with radioactive phosphatidylcholine, radioactivity was observed in cytidine 5′-diphosphate choline and diglyceride. It is thus proposed that the following pathways of phospholipid biosynthesis are operative in Ehrlich ascites cells:[Formula: see text]The operation of these pathways would explain the observed incorporation of both ethanolamine and methionine into sphingomyelin.
Chemical Modification of Human Lysozyme. Acetylation and Nitration of Tyrosine
Authors: Fawcett R. L. , Limbird T. J. , Oliver Sandra L. , Borders Jr. C. L.
Published: December 2009

When human lysozyme is reacted with a 60 M excess of N-acetylimidazole, only one of six tyrosine residues and two amino groups are acetylated. The acetylated lysozyme is 1.2 times as active towards M. lysodeikticus as the unmodified enzyme. When human lysozyme is reacted with a 4 M excess of tetranitromethane, approximately one tyrosine is nitrated. The tetranitromethane also simultaneously induces a high degree of polymerization of the lysozyme. In a typical experiment, nitration leads to a polymerized product that has only 25% of the activity of unmodified enzyme towards M. lysodeikticus. The polymerized lysozyme can be separated into several components by gel filtration on Sephadex G-75. Enzyme activity analyses of the chromatographed lysozyme oligomers indicate that tetranitromethane reduces the activity of human lysozyme primarily by polymerization, since the lysozyme monomer, which contains one nitrotyrosine per molecule, has 65% activity while the trimer has only 5% activity. N-Acetylglucosamine, N,N′-diacetylchitobiose, and N,N',N″-triacetylchitotriose, all inhibitors or substrates of human lysozyme, prevent neither the nitration of the single tyrosine residue nor the polymerization due to tetranitromethane action.
Porcine Sugar Nucleotide: Glycoprotein Glycosyltransferases. I. Blood Serum and Liver Sialyltransferase
Authors: Hudgin Roger L. , Schachter Harry
Published: December 2009

The properties of CMP-N acetylneuraminic acid: glycoprotein sialyltransferase have been studied in pork serum, a crude pork liver homogenate, and a soluble acetone powder extract prepared from pork liver. Whereas the crude liver homogenate enzyme is activated by the detergent Triton X-100, this detergent has no effect on the activities of either serum or acetone powder extract; since high-speed centrifugation does not sediment the enzyme activities of the latter two preparations, it is concluded that they are soluble. Comparison of the membrane-bound and soluble liver enzymes indicates that the membrane modifies kinetic behavior only to a limited extent. In both liver and serum, a single sialyltransferase is responsible for incorporation of sialic acid into α1-acid glycoprotein, fetuin, and N-acetyllactosamine, and sialic acid incorporation occurs whenever a terminal galactose linked (β, 1 → 4) to a penultimate N-acetylglucosamine is presented to the enzyme. Although the serum enzyme resembles the liver enzyme, both the source and function of serum sialyltransferase are unknown.
Studies on Chymotrypsin-P. I. Characterization
Authors: Shaw M. C. , Viswanatha T.
Published: December 2009

The physicochemical properties of chymotrypsin-P obtained by the papain activation of chymotrypsinogen have been investigated. The molecular weight of this enzyme as determined by gel filtration technique has been found to be 24 000 ± 1000. The amino acid residues occupying the N-terminal positions and the composition of the B- and C-chains of chymotrypsin-P are identical with those found in α-chymotrypsin. Thus the difference between the two enzymes is restricted to the composition of their A-chains.
The Bottle-Nosed Dolphin Tursiops truncates: Fatty Acid Composition of Milk Triglycerides
Authors: Ackman R. G. , Eaton C. A. , Mitchell E. D.
Published: December 2009

Triglyceride from the milk of the bottle-nosed dolphin Tursiops truncatus has been examined and found to correspond in fatty acid details to the composition of the depot fats of marine mammals generally. No isovaleric or other short-chain acids were present.
Recognition of 'Early' and 'Late' Biosynthetic Classes of Ribosomal Proteins in Escherichia coli
Authors: Beatty Barbara G. , Wong J. Tze-Fei
Published: December 2009

When cells of a pyrimidine-requiring strain of Escherichia coli were starved of uridine, there occurred a sequential turn-off in the synthesis of different ribosomal proteins. This observation provided a basis for distinguishing between ribosomal proteins exhibiting an 'early' turn-off from those exhibiting a 'late' turn-off. Both the 'early' and 'late' classes were represented on both the 30 S and 50 S subunits, but the 30 S subunit was enriched in 'early' ribosomal proteins relative to the 50 S subunit.
Subcellular Distribution of DNA Polymerase Activity in Newborn Rat Brain and Liver
Authors: Murthy M. R. V. , Bharucha A. D.
Published: December 2009

DNA polymerase activities were determined in the cytoplasmic soluble, the nuclear soluble, and the nuclear particulate fractions of newborn rat brain and liver. The results indicate that a majority of the brain nuclear enzyme may be bound to particulate material while a majority of the liver nuclear enzyme may be free or only loosely bound. Although the subcellular distributions of DNA polymerase activity are widely different in newborn brain and liver, the enzyme activity in any given subcellular fraction is higher in liver than in brain.
Localization of the Basic Aminopeptidases in Escherichia coli
Authors: Matheson A. T. , Visentin L. P. , Boutet A. , Rollin C. F.
Published: December 2009

The basic aminopeptidase activity was found in both the 30 S and 50 S ribosomal subunit of Escherichia coli B; the specific activity of the enzyme in the 30 S particle was about six times that found in the 50 S particle. Although about 50% of the enzyme was released from E. coli B ribosomes on dissociation into the subunits, this was not observed with E. coli Q-13, a ribonuclease I-less strain. The partition of the basic aminopeptidase activity between the soluble and ribosomal fractions (isolated in 60 mM KCl) of E. coli was determined by the strain of E. coli used, as well as the stage and temperature of growth. Under similar growth conditions, a significantly greater amount of enzyme was found in the ribosomal fraction of E. coli B than in the corresponding fraction of E. coli K-12. When E. coli B cells were disrupted in 300 mM KCl, over 90% of the enzyme was found in the soluble fraction. The remaining 10% on the ribosomal particle had enriched activity towards methionyl peptides suggesting that more than one enzyme is present in the basic aminopeptidase fraction.
Preparation and Properties of Solid-Supported Urease
Authors: Sundaram P. V. , Crook E. M.
Published: December 2009

The preparation and properties of solid-supported urease (urea amidohydrolase, EC 3.5.1.5) are described. The supported enzyme derivatives were made by adsorbing the enzyme onto the surface of kaolinite. The preparations made at various pH values between 4.3 and 9.0 were found to have the enzyme protein attached irreversibly. The supported enzyme showed a considerable activation at all pH values except at pH 4.3, the maximum increase in activity being nearly twofold. The pH optimum for the enzyme remained unchanged at pH 6.65 with Km values showing an increase at most pH values.
DNA Polymerase Activity in the Nuclei of Developing Rat Brain and Liver
Authors: Murthy M. R. V. , Bharucha A. D.
Published: December 2009

The level of DNA polymerase activity per tissue in the soluble fraction (NS) of rat brain nuclei underwent a twofold increase during the first 2 weeks after birth and then declined steeply over the next 10 weeks to a value only one-third ofthat in the newborn. In contrast to brain, the enzyme activity per liver increased continuously from birth up to 12 weeks of age (10-fold). The DNA contents of these tissues appear to be quantitatively related to the DNA polymerase activities in the respective NS fractions. These preparations did not phosphorylate thymidylate to TTP, but could convert the other three complementary deoxynucleotides to the triphosphate level. This latter activity was highest in the NS fraction of the newborn rat brain and decreased drastically with growth. In the corresponding fraction of liver, the activity remained relatively stable throughout the growth period tested.
Labelling of Proteins by Isolated Rat Liver Nuclei
Authors: Anderson K. M. , Slavik M. , Elebute O. P.
Published: December 2009

Rat liver nuclei, isolated in hypertonic sucrose solution and washed with Triton X-100, incorporate radioactive amino acids into hot trichloroacetic acid insoluble materials.Optical and biochemical evidence of nuclear purity is presented. The temperature-dependent incorporation continued for 20–30 min, and was proportional to the concentrations of both nuclear protein between 0.5–1.5 mg/ml, and radioactive amino acid. The radioactive product was degraded by pronase, and a number of inhibitors reduced incorporation, but only if present at [Formula: see text]. Proteins extracted from labelled nuclei and microsomes and examined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis at pH 7.2 exhibited different patterns of radioactivity. This provides further support for the concept of protein synthesis intrinsic to rat liver nuclei.A teleological argument for the function of nuclear protein synthesis is discussed.
Bile Acid Metabolism in Mammals. III. Sex Difference in the Bile Acid Composition of Rat Bile
Authors: Yousef I. M. , Kakis G. , Fisher M. M.
Published: December 2009

Bile was collected from 12 rats, six of each sex, for the first 5 h following the creation of a biliary fistula. The bile acid content of the bile was analyzed by combined thin-layer and gas chromatographic techniques. Total bile acids and the glycine and taurine conjugates were measured. Although bile volumes and total bile acid outputs were similar in rats of both sexes, significant sex differences were found in the amounts of individual bile acids secreted. The female rat secretes considerably more cholic and lithocholic acids, and considerably less β-muricholic, deoxycholic, and hyodeoxycholic acids. The female rat also secretes less glycine-conjugated bile acids and in contrast to the male the bulk of this is glycocholic acid. The greater secretion of β-muricholic acid by the male rat suggests that this sex has a more efficient mechanism for the metabolism of chenodeoxycholic acid.
Evidence for Biosynthetical Equivalence of the Epimeric Isoleucine Residues in Angolide
Authors: Okotore R. O. , Russell D. W.
Published: December 2009

Pithomyces sacchari was grown on media containing L-valine. Instead of the metabolite angolide (cyclo-L-α-hydroxyisovaleryl1-erythro-L-isoleucyl2-L-α-hydroxyisovaleryl3-threo-D-isoleucyl4), synthesized on un-supplemented media, it produced a mixture with very similar physical properties. Acid hydrolysis liberated erythro-L- and threo-D-isoleucines (1:1), and DL-valine in amounts proportional to the exogenous valine concentration; L-α-hydroxyisovaleric acid was the only other component. Radioactivity from L-valine-U-14C was incorporated without dilution into valine, and with extensive dilution into the hydroxy acid.Partial fractionation of the mixture was achieved by column chromatography. Mass spectra of two fractions, containing different proportions of valine, were compared with the spectrum of angolide. A simple mathematical treatment showed that the fractions contained angolide, its divaline homologue, and a homologue with only one isoleucine replaced by valine. This must be a 1: 1 mixture of the two possible isomers, since any deviation from this ratio is inconsistent with the analytical results. It follows that the erythro-L- and the threo-D-isoleucine residues of angolide are equivalent with respect to their replacement by valine. It is inferred that angolide biosynthesis involves a cyclic intermediate containing both amino acid residues in the L configuration.
Studies on Spermatogenesis in Rats. IV. Rates of Oxidation of Palmitate and Pyruvate by Various Testicular Cell Populations
Authors: Lin C. H. , Fritz I. B.
Published: December 2009

Measurements are reported on the rates of oxidation of 14C-1-palmitate, 14C-1-pyruvate, and 14C-2-pyruvate by cell suspensions obtained from testes of normal rats of varying ages and from hypophysectomized regressed rats. Highest conversion rates of labeled pyruvate to CO2 were observed in testes from 24-day-old rats, in which all germinal cells except spermatids and spermatozoa were present. Cell suspensions from testes of adult rats, containing predominantly spermatids, had relatively low rates of palmitate and pyruvate oxidation. These rates were increased in cell suspensions from testes of regressed hypophysectomized rats towards those observed in testicular cell preparations from immature rats. The predominant cell types in testes from hypophysectomized, regressed rats are spermatogonia and early spermatocytes, although early stage spermatids are also present in lesser numbers. The ketogenic enzyme capacity was greatest in particulate preparations obtained from testes of normal 14-day-old rats, in which the predominant germinal cells present are spermatogonia. The activity of succinyl-CoA: 3-oxoacid CoA-transferase was also highest in these preparations. Cell suspensions from testes of 14-day-old rats incorporated significant amounts of labeled palmitate and pyruvate into acetoacetate, whereas cell suspensions from testes of other groups of animals examined did not. The data are discussed in relation to factors controlling rates of fatty acid oxidation in various germinal epithelial cells. It is concluded that spermatocytes have highest rates of pyruvate oxidation, but that both spermatogonia and spermatocytes have relatively high rates of palmitate oxidation. Since spermatogonia also were shown to contain the relatively highest ketogenic enzymic capacity, and since these cells had previously been observed to have lowest levels of carnitine acetyltransferase (CAT), it may be deduced that high CAT activity is not required for fatty acid oxidation or ketogenesis by testicular cells.
A Spin Label Study of the Influence of Cholesterol on Egg Lecithin Multibilayers
Authors: Lapper Roy D. , Paterson Sabina J. , Smith Ian C. P.
Published: December 2009

A detailed electron spin resonance study of a cholestane spin label in hydrated egg lecithin multibilayers of variable cholesterol content is presented. Several theoretical models are proposed in an attempt to explain the observed electron spin resonance spectra for the egg lecithin–cholesterol multibilayer system; we conclude that the most probable model is that of restricted random walk of individual spin labels where the amplitude of the random walk decreases from about 46° at 0 mol% cholesterol content to a minimum of 17° at 55 mol% cholesterol. Also, as the cholesterol content of the multibilayers increases, so the rate of random walk decreases from rapid to intermediate on the electron spin resonance time scale. The results clearly indicate that cholesterol is able to order egg lecithin films, orientating all molecules towards a normal to the surface of the film and decreasing their mobility. The condensing and stiffening influence of cholesterol in phospholipids is undoubtedly one of its major roles in biological membranes.
Stimulation of Onset of the Phase of Rapid Hemoglobin Formation in the Chick Blood Islands by the Wax Fraction of Egg Yolk
Authors: Wainwright S. D. , Wainwright Lillian K.
Published: December 2009

6-Somite stage (27–30 h) chick blastodiscs incubated on egg homogenate medium for 4 h and then transferred to minimal medium for a further 3 h contain more hemoglobin than similar blastodiscs maintained on minimal medium. The stimulatory component(s) of the egg homogenate has been located in the wax fraction of egg yolk.
Purification and Properties of Rat Liver Nuclear Protein Kinases
Authors: Desjardins P. R. , Lue P. F. , Liew C. C. , Gornall A. G.
Published: December 2009

Two protein kinases, designated NI and NII, have been isolated from rat liver nuclei. These enzymes have a similar pH optimum and phosphorylate phosvitin and casein more readily than histone. Both enzymes require magnesium for activity. In the absence of Mg2+, other divalent cations such as Ca2+, Co2+, and Mn2+ can substitute partially for Mg2+ when the reaction is catalyzed by NI. With NII, only Co2+ showed any activity in the absence of Mg2+. Magnesium decreased the apparent Km for ATP of protein kinase NI without changing the Vmax of the reaction, and decreased the apparent Km's for both ATP and casein, while increasing the Vmax of the reaction threefold with protein kinase NII. Both enzymes are stimulated about twofold by low concentrations (0.1–0.3 M) of NaCl, KCl, and sodium acetate, whereas higher concentrations (> 0.5 M) inhibit their activities. Both enzymes are inhibited by low concentrations of NaF (0.02 M) and (NH4)2SO4 (0.1 M). NI and NII were found to have sedimentation coefficients of 3.6 S and 10.8 S, respectively. The nuclear protein kinases are not activated by cyclic AMP or cyclic GMP, and are not inhibited by the heat-stable cyclic AMP-dependent protein kinase inhibitor.
Excretion of Conjugated 11-Deoxy-17-ketosteroids in "Essential" Hypertension
Authors: Dey A. C. , Abbott E. C. , Rusted I. E. , Senciall I. R.
Published: December 2009

The excretion of androstenedione and the sulfate and glucuronide fractions of androsterone, etiocholanolone, and dehydroepiandrosterone has been measured in the urine of male and female "essential" hypertensives and normotensives by gas–liquid chromatography. Aldosterone was measured by a double isotope derivative procedure. Excretion of dehydroepiandrosterone sulfate and etiocholanolone glucuronide was significantly reduced (P < 0.001) in the urine of the hypertensive group, whereas excretion of androsterone glucuronide (P < 0.01) and androstenedione (P < 0.01) was increased. The androsterone/etiocholanolone ratio was also increased from 1.45 ± 0.79 (S.D.) in the normotensive group to 3.94 ± 2.19 (S.D.) in the hypertensive group (P < 0.001), suggesting a relative 5β-reductase activity deficiency in "essential" hypertension.It was concluded that the markedly decreased excretion of dehydroepiandrosterone sulfate found in this study and another was not a consequence of a modified peripheral metabolism.
The Kinetics of Reactions Catalyzed by Alkaline Phosphatase: The Effects of Added Nucleophiles
Authors: Hinberg Irwin , Laidler Keith J.
Published: December 2009

An experimental study was made of the hydrolyses of phenyl phosphate and p-nitrophenyl phosphate catalyzed by chicken intestinal alkaline phosphatase. The work was done at pH 8.0 and 10.0, 25.0 °C, and an ionic strength of 0.1 M, and particular attention was paid to the kinetics of formation of the products in the presence of Tris and ethanolamine. It was found that the rates of formation of phenol or p-nitrophenol (P1) and of the phosphorylated nucleophile (P3) were dependent on the concentration of added nucleophile; on the other hand the rate of formation of phosphate (P2) and the Michaelis constant were independent of nucleophile concentration. This result cannot be reconciled with any of the mechanisms discussed in the preceding paper with the exception of mechanism VI, which is an elaboration of one proposed by Trentham and Gutfreund; mechanism VI is[Formula: see text]where W is water and N the alternative nucleophile. ES and E*S are two conformers of the enzyme–substrate complex, and E*S′ and ES′ two forms of the phosphorylated enzyme; only the latter can react with water and only the former with nucleophile.
ATOMIC COHERENT STATES AS THE EIGENSTATES OF A TWO-DIMENSIONAL ANISOTROPIC HARMONIC OSCILLATOR IN A UNIFORM MAGNETIC FIELD
Authors: MENG XIANG-GUO , WANG JI-SUO , FAN HONG-YI
Published: December 2009

In the newly constructed entangled state representation embodying quantum entanglement of Einstein, Podolsky and Rosen, the usual wave function of atomic coherent state ∣τ〉 = exp (μJ+-μ*J-)∣j, -j〉 turns out to be just proportional to a single-variable ordinary Hermite polynomial of order 2j, where j is the spin value. We then prove that a two-dimensional time-independent anisotropic harmonic oscillator in a uniform magnetic field possesses energy eigenstates which can be classified as the states ∣τ〉 in terms of the spin values j.
DISTURBANCE DUE TO PERIODIC THERMAL LOAD IN A PIEZOTHERMOELASTIC HALF-SPACE
Authors: SHARMA J. N. , THAKUR ANITA D. , SHARMA Y. D.
Published: December 2009

The present paper deals with the disturbances due to periodic strip thermal sources, acting on the rigidly fixed, charge free (open circuit) or electrically shorted (closed circuit) surface of a homogeneous, transversely isotropic, thermally conducting generalized piezothermoelastic half-space. The Laplace and Fourier transform technique have been employed to solve the model consisting of partial differential equations and boundary conditions in the transformed domain. In order to obtain the displacements, temperature change, stresses, electric potential and electric displacement in the physical domain, the integral transforms have been inverted by using a numerical inversion technique. Finally, to illustrate the analytical results, the numerical computations of various field parameters have been carried out from the relevant expressions and relations for cadmium selenide (CdSe) material by developing a FORTRAN code. The computer simulated results are presented graphically in respect of different considered field functions with load frequency and epicentral distance for 6 mm cadmium selenide (CdSe) material half-space.
A MESHLESS METHOD ANALYSIS OF ELASTO-PLASTIC CONTACT PROBLEMS WITH FRICTION
Authors: BOUDAIA ELHASSAN , BOUSSHINE LAHBIB , DE SAXCE GERY , CHAABA ALI
Published: December 2009

We present a theoretical and numerical analysis of incremental elasto-plastic problems based on the meshless method and the mathematical programming. This study is done on an elasto-plastic material with isotropic hardening obeying to the von Mises criterion. The transformation method is adopted to impose the essential boundary condition. The Coulomb's dry friction contact is used to implement the frictional boundary conditions and is formulated by the bipotential method which leads to only one principle of minimum in displacement. The numerical analysis results obtained by the method proposed in this paper are in good agreement with those obtained by FEM.
DYNAMICS OF A 2-DOF DRY FRICTION SYSTEM UNDER TWO-FREQUENCY EXCITATIONS
Authors: CHENG GONG , ZU JEAN W.
Published: December 2009

In this paper, the dynamics of a two-degree-of-freedom block-on-belt system subjected to both dry friction and external excitations is studied. The dry friction in the system follows the classical Coulomb's law, and the external excitations consist of two harmonic forces with different frequencies. In the study, a new two-dimensional (2-D) map is developed, which reduces the system without losing its essential dynamic features and greatly simplifies the investigation. On the basis of the 2-D map, bifurcation analysis and the computation of Poincaré sections and Lyapunov exponents can be carried out straightforwardly. Numerical simulations are performed, in which the proposed 2-D map is proved to be very effective and provide a powerful tool to understand the dynamical behavior of the system. Numerical results show that the system possesses rich dynamics characterized by periodic, quasi-periodic and chaotic attractors. Furthermore, it is found that the two-frequency excitation has significant influence on the dynamical behavior of the system.
Actin polymerization in differentiated vascular smooth muscle cells requires vasodilator-stimulated phosphoprotein
Authors: Kim Hak Rim , Graceffa Philip , Ferron François , Gallant Cynthia , Boczkowska Malgorzata , Dominguez Roberto , Morgan Kathleen G.
Published: December 2009

Our group has previously shown that vasoconstrictors increase net actin polymerization in differentiated vascular smooth muscle cells (dVSMC) and that increased actin polymerization is linked to contractility of vascular tissue (Kim et al., Am J Physiol Cell Physiol 295: C768–778, 2008). However, the underlying mechanisms are largely unknown. Here, we evaluated the possible functions of the Ena/vasodilator-stimulated phosphoprotein (VASP) family of actin filament elongation factors in dVSMC. Inhibition of actin filament elongation by cytochalasin D decreases contractility without changing myosin light-chain phosphorylation levels, suggesting that actin filament elongation is necessary for dVSM contraction. VASP is the only Ena/VASP protein highly expressed in aorta tissues, and VASP knockdown decreased smooth muscle contractility. VASP partially colocalizes with α-actinin and vinculin in dVSMC. Profilin, known to associate with G actin and VASP, also colocalizes with α-actinin and vinculin, potentially identifying the dense bodies and the adhesion plaques as hot spots of actin polymerization. The EVH1 domain of Ena/VASP is known to target these proteins to their sites of action. Introduction of an expressed EVH1 domain as a dominant negative inhibits stimulus-induced increases in actin polymerization. VASP phosphorylation, known to inhibit actin polymerization, is decreased during phenylephrine stimulation in dVSMC. We also directly visualized, for the first time, rhodamine-labeled actin incorporation in dVSMC and identified hot spots of actin polymerization in the cell cortex that colocalize with VASP. These results indicate a role for VASP in actin filament assembly, specifically at the cell cortex, that modulates contractility in dVSMC.
Tetramerization domain mutations in KCNA5 affect channel kinetics and cause abnormal trafficking patterns
Authors: Burg Elyssa D. , Platoshyn Oleksandr , Tsigelny Igor F. , Lozano-Ruiz Beatriz , Rana Brinda K. , Yuan Jason X.-J.
Published: December 2009

The activity of voltage-gated K+ (KV) channels plays an important role in regulating pulmonary artery smooth muscle cell (PASMC) contraction, proliferation, and apoptosis. The highly conserved NH2-terminal tetramerization domain (T1) of KV channels is important for proper channel assembly, association with regulatory KV β-subunits, and localization of the channel to the plasma membrane. We recently reported two nonsynonymous mutations (G182R and E211D) in the KCNA5 gene of patients with idiopathic pulmonary arterial hypertension, which localize to the T1 domain of KCNA5. To study the electrophysiological properties and expression patterns of the mutants compared with the wild-type (WT) channel in vitro, we transfected HEK-293 cells with WT KCNA5, G182R, E211D, or the double mutant G182R/E211D channel. The mutants form functional channels; however, whole cell current kinetic differences between WT and mutant channels exist. Steady-state inactivation curves of the G182R and G182R/E211D channels reveal accelerated inactivation; the mutant channels inactivated at more hyperpolarized potentials compared with the WT channel. Channel protein expression was also decreased by the mutations. Compared with the WT channel, which was present in its mature glycosylated form, the mutant channels are present in greater proportion in their immature form in HEK-293 cells. Furthermore, G182R protein level is greatly reduced in COS-1 cells compared with WT. Immunostaining data support the hypothesis that, while WT protein localizes to the plasma membrane, mutant protein is mainly retained in intracellular packets. Overall, these data support a role for the T1 domain in channel kinetics as well as in KCNA5 channel subcellular localization.
Soluble Flt-1 gene therapy ameliorates albuminuria but accelerates tubulointerstitial injury in diabetic mice
Authors: Kosugi Tomoki , Nakayama Takahiro , Li Qiuhong , Chiodo Vince A. , Zhang Li , Campbell-Thompson Martha , Grant Maria , Croker Byron P. , Nakagawa Takahiko
Published: December 2009

VEGF is recognized as a major mediator in the development of diabetic nephropathy. Soluble Flt-1 (sFlt-1) is the endogenous inhibitor of VEGF, and recently genetic overexpression of sFlt-1 in the podocyte was shown to be protective in murine diabetic nephropathy. In this study, we performed a translational study to determine whether an intramuscular gene transfer of sFlt-1 can prevent the progression of renal disease in diabetic db/db mice. Adeno-associated virus-1 (AAV1) encoding human sFlt-1 in two different doses was intramuscularly administrated in db/db and wild-type mice. The sFlt-1-AAV1 treatment significantly increased serum sFlt-1 level at 4 and 8 wk. A dose that was developed in this study caused minimal abnormalities in normal mice but reduced albuminuria in diabetic db/db mice. In renal histology, sFlt-1 treatment at this dose had minimal effects on mesangial expansion in diabetic mice, whereas podocyte injury was significantly improved, at 8 wk. Unfortunately, tubulointerstitial injury was markedly exacerbated by sFlt-1 treatment in association with a reduction in endogenous VEGF expression and peritubular capillary loss. In conclusion, gene therapy with sFlt-1-AAV1 protects podocytes but accelerates tubulointerstitial injury in diabetic db/db mice. These data suggest systemic overexpression of sFlt-1 will not likely be useful for treating diabetic nephropathy.
Metabotropic Glutamate Receptors in Median Preoptic Neurons Modulate Neuronal Excitability and Glutamatergic and GABAergic Inputs From the Subfornical Organ
Authors: Kolaj Miloslav , Renaud Leo P.
Published: December 2009

Cardiovascular and behavioral responses to circulating angiotensin require intact connectivity along the upper lamina terminalis joining the subfornical organ (SFO) with the median preoptic nucleus (MnPO). In the present study on MnPO neurons, we used whole cell patch-clamp recording techniques in brain slice preparations to evaluate the influence of metabotropic glutamate receptor (mGluR) agonists on modulating their intrinsic excitability and SFO-evoked glutamatergic and GABAergic postsynaptic currents. In 22/36 cells, bath application of a mGluR group I agonist ( S)-3,5-dihydroxyphenylglycine (DHPG) induced a TTX-resistant inward current coupled with decrease in a membrane K+conductance but also a possible increase in a nonselective cationic conductance. By contrast, 27/49 cells responded to a mGluR group II agonist (2S,2′R,3′R)-2-(2′,3′-dicarboxycyclopropyl)glycine (DCG IV) with a TTX-resistant outward current and increase in membrane conductance that reversed around −95 mV, suggesting opening of K+channels. None of 19 cells responded to the mGluR group III agonist l-(+)-2-amino-4-phosphonobutyric acid (l-AP4). Agonists for all mGluR groups suppressed SFO-evoked excitatory postsynaptic currents and significantly increased paired-pulse ratios, implying a presynaptic mechanism. Only the mGluR group II agonist significantly reduced SFO-evoked inhibitory postsynaptic currents and caused an increase in paired-pulse ratios. These results suggest a complexity of pre- and postsynaptic mGluRs are available to modulate rapid neurotransmission along the upper lamina terminalis from SFO to MnPO.
Long human CHGA flanking chromosome 14 sequence required for optimal BAC transgenic “rescue” of disease phenotypes in the mouse Chga knockout
Authors: Vaingankar Sucheta M. , Li Ying , Corti Angelo , Biswas Nilima , Gayen Jiaur , O'Connor Daniel T. , Mahata Sushil K.
Published: December 2009

Chromogranin A (CHGA) plays a catalytic role in formation of catecholamine storage vesicles and also serves as precursor to the peptide fragment catestatin, a catecholamine secretory inhibitor whose expression is diminished in the hypertensive individuals. We previously reported the hypertensive, hyperadrenergic phenotype of Chga−/− knockout (KO) mice and rescue by the human ortholog. In the present study, we compare two humanized CHGA mouse models. Into the Chga null background, by bacterial artificial chromosome transgenesis human CHGA transgene has been introduced. Both lines have the complete ∼12 kbp CHGA gene integrated stably in the genome but have substantial differences in CHGA expression, as well as consequent sympathochromaffin biochemistry and physiology. A mouse model with longer-insert Hum CHGA31 displays integration encompassing not only CHGA but also long human flanking sequences. This is in contrast to mouse model Hum CHGA19 with limited flanking human sequence co-integrated. As a consequence, Hum CHGA19 mice have normal though diminished pattern of spatial expression of CHGA, and 14-fold lower circulating CHGA, with failure to rescue KO phenotypes to normalcy. In the longer-insert Hum CHGA31 mice, catecholamine secretion, exaggerated responses to environmental stress, and hypertension were all alleviated. Promoter regions of the transgenes in both Hum CHGA19 and Hum CHGA31 display minimal CpG methylation, weighing against differential “position effects” of integration, and thus suggesting that lack of cis elements required for optimal CHGA expression occurs in Hum CHGA19 mice. Such “humanized” CHGA mouse models may be useful in probing the physiological consequences of variation in CHGA expression found in humans, with consequences for susceptibility to hypertension and cardiovascular disease.
Fast Track Liver Resection: The Effect of a Comprehensive Care Package and Analgesia with Single Dose Intrathecal Morphine with Gabapentin or Continuous Epidural Analgesia
Authors: Koea Jonathan B. , Young Yatin , Gunn Kerry
Published: December 2009

Background. A comprehensive care package for patients undergoing hepatectomy was developed with the aim of minimal physiological disturbance in the peri-operative period. Peri-operative analgesia with few gastrointestinal effects and reduced requirement for intravenous (IV) fluid therapy was central to this plan. Methods. Data on 100 consecutive patients managed with continuous epidural infusion (n = 50; bupivicaine 0.125% and fentanyl 2 g/mL at 0.1 mL/kg/hr) or intrathecal morphine (n = 50; 300 g in combination with oral gabapentin 1200 mg preoperatively and 400 mg bd postoperatively) was compared. Results. The epidural and intrathecal morphine groups were equivalent in terms of patient demographics, procedures and complications. Patients receiving intrathecal morphine received less intra-operative IV fluids (median 1500 mL versus 2200 mL, ), less postoperative IV fluids (median 1200 mL versus 4300 mL, ) than patients receiving epidural infusion. Patients managed with intrathecal morphine established a normal dietary intake sooner (16 hours versus 20 hours, ) and had shorter hospital stays than those managed with epidural infusions (4.7 0.9 days versus 6.8 1.2 days, ). Conclusions. Single dose intrathecal morphine is a safe and effective means of providing peri-operative analgesia. Patients managed with intrathecal morphine have reduced peri-operative physiological disturbance and return home within a few days of hepatic resection.
Renal Angiomyolipoma Associated with Inferior Vena Cava Thrombus
Authors: Durand Xavier , Renard-Penna Raphaelle , Comperat Eva , Bitker Marc-Olivier , Richard Francois
Published: December 2009

A 57-year-old woman was found to have an inferior vena cava involvement of a known sinusal angiomyolipoma incompletely resected three years beforehand. Intravascular extension into the IVC of angiomyolipoma has rarely been reported. We present a new case and reconsider the literature about this uncommon complication of a benign renal tumor.