bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential effects of eicosapentaenoic acid and docosahexaenoic acid on human skin fibroblasts
Authors: Brown Eric R. , Subbaiah Papasani V.
Published: December 2006

To better understand the mode of action of ω3 fatty acids in cell membranes, human foreskin fibroblasts were grown in serum‐free medium supplemented with 50 μM oleic acid linoleic acid, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), and the effects on membrane composition, fluorescence polarization and enzyme activities were followed. The cells were enriched with EPA and DHA up to 7 and 13% of total lipids, respectively, of which >95% was associated with phospholipids. In addition, the concentration of 22∶5n−3 increased with both EPA and DHA to 7.5, and 2.1% of the total fatty acids, respectively. When compared to controls (oleic acid), cells treated with DHA showed a decrease in cholesterol, phospholipids, arachidonic acid (AA) and free cholesterol/phospholipid ratio (P<0.05). In the presence of EPA, only decreases in AA and cholesterol were significant (P<0.05). Membrane fluidity, assessed by fluorescence anisotropy, was increased 16% in cells enriched with DHA (P<0.05), but showed no change with EPA or linoleic acid. There was an increase in membrane‐associated 5′‐nucleotidase (+27%) and adenylate cyclase (+19%) activities (P<0.05), in DHA‐enriched, but not in EPA‐enriched cells, when compared with oleate controls. The studies show that incorporation of DHA, but not EPA, into cell membranes of fibroblasts alters membrane biophysical characteristics and function. We suggest that these two major n−3 fatty acids of fish oils have differential effects on cell membranes, and this may be related to the known differences in their physiological effects.
Comparison of linoleic acid and eicosapentaenoic acid incorporation into human breast cancer cells
Authors: Hatala Mary Ann , Rayburn Jodie , Rose David P.
Published: December 2006

To gain some insight into the mechanisms involved in the opposing effects of linoleic acid (LA) and eicosapentaenoic acid (EPA) on the growth and invasiveness of MDA‐MB‐435 human breast cancer cells, the dynamics of the uptake by cells and the incorporation of [14C]LA and [14C]EPA into major lipid and phospholipid pools, as well as the effects of unlabeled EPA or LA on the uptake and distribution of [14C]LA or [14C]EPA, respectively, were examined. Cells were exposed to [14C]LA (1.28 μg/mL) or [14C]EPA (1.0 μg/mL) and unlabeled EPA or LA, respectively, at 0, 1, 4 and 16 μg/mL for 24 h in serum‐free media. The uptake of each fatty acid (FA) was linear over time and was not affected by the presence of the opposing FA. For both FA, 80–90% was incorporated into the phospholipid fraction with the remaining 10–20% in neutral lipids. The relative distribution profile of [14C]LA among the phospholipid classes indicated a preferential incorporation into phosphatidylcholine (65%), whereas [14C]EPA was mostly found in phosphatidylethanolamine (58%). In the presence of unlabeled EPA or LA at various concentrations, corresponding dose‐dependent shifts of [14C]LA or [14C]EPA from the phospholipid to the neutral lipid pool were noted, which did not alter the relative distribution of the FA among the phospholipid classes. Exogenous exposure to EPA or LA increased its content in membrane phospholipids while concurrently decreasing LA or EPA content, respectively, in a dose‐dependent manner. Arachidonic acid content of membrane phospholipids remained constant. The divergent distribution profiles of LA and EPA within the phospholipid compartment provides some insight into the mechanisms of their opposing effects on MDA‐MB‐435 cell growth and invasiveness. Also, the effects of LA and EPA on the uptake and distribution of their opposing FA shed some light on the mechanisms mediating their competitive effects.
Dietary ω3 fatty acids and cholesterol modify enterocyte microsomal membrane phospholipids, cholesterol content and phospholipid enzyme activities in diabetic rats
Authors: Keelan M. , Doring K. , Tavernini M. , Wierzbicki E. , Clandinin M. T. , Thomson A. B. R.
Published: December 2006

Diabetes‐associated changes in intestinal uptake of nutrients are modified by isocaloric variations in the type of dietary lipids, and are associated with alterations in the phospholipid and fatty acyl content of the intestinal brush border membrane. The present study was designed to test the hypothesis that diet‐ and diabetes‐associated changes in enterocyte microsomal membrane phospholipids are due to variations in the activity of two phospholipid metabolizing enzymes, 1,2‐diacylglycerol: CDP choline cholinephosphotransferase (CPT) and phosphatidylethanolamine methyltransferase (PEMT). Adult female Wistar rats were fed one of four semisynthetic diets—beef tallow low in cholesterol (BT), beef tallow high in cholesterol (BTC), fish oil low in cholesterol (FO) or fish oil high in cholesterol. In half of the animals, diabetes mellitus was produced by injection of streptozotocin. Jejunal and ileal enterocyte microsomes (EMM) were isolated and analyzed for cholesterol and phospholipids, as well as for CPT and PEMT activities. In control animals, feeding FO reduced EMM total phospholipids including phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol. Feeding FO resulted in a greater than 95% reduction in the activity of CPT. Diabetes was associated with increased jejunal EMM total phospholipids including sphingomyelin (SM) and PE, without associated changes in CPT or PEMT. Dietary cholesterol supplementation did not effect EMM total cholesterol or phospholipid composition in control rats fed BT or FO, but was associated with an increase in EMM cholesterol in diabetic rats fed BT or FO. A decrease in total phospho‐lipids due to a decline in SM, PC and PE in diabetic rats fed FO was not associated with changes in the activities of CPT or PEMT in EMM. Thus (i) enterocyte microsomal membrane cholesterol and phospholipid contents are influenced by diabetes, dietary cholesterol and the type of fatty acid in the diet, and (ii) changes in phospholipid composition are not fully explained by alterations in the activities of CPT and PEMT.
Peroxidation reactions in plant membranes: Effects of free fatty acids
Authors: Barclay Katherine D. , McKersie Bryan D.
Published: December 2006

Free fatty acids accumulate in plant membranes after exposure of plants to environmental stress, such as freezing and desiccation. Fatty acid accumulation has been linked to various biophysical changes and to the occurrence of lipid peroxidation, but the relationships appear complex and inconsistent. The interactions between oxygen free radicals, free fatty acids and lipid peroxidation in plant membranes were examined further by studying peroxidation reactions in a model membrane system composed of a complex mixture of plant phospholipids, including various free fatty acids. Multilamellar liposomes were treated with oxygen free radicals generated from iron ascorbate. Increased concentrations of free palmitic acid up to 10 mol% (fatty acid/phospholipid) reduced the production of aldehydes detected by the thiobarbituric acid assay, but enhanced the production of fluorescent products. By contrast, increased concentrations of free linolenic acid increased aldehyde production and reduced the formation of fluorescent products. The two free fatty acids both enhanced the susceptibility of phospholipids to degradation as shown by the reduced recovery of esterified polyunsaturated fatty acids (linoleic and linolenic). The free radical reactions with or without free fatty acid additions catalyzed the selective degradation of phospholipids in the order phosphatidylethanolamine > phosphatidylcholine > phosphatidylinositol > phosphatidylglycerol. Selective degradation of phospholipids is often observed after periods of environmental stress or during senescence of plants, and has been cited as evidence for the involvement of phospholipases in these degenerative processes. The results indicate that selectivity is not a criterion for eliminating the involvement of oxygen free radicals in these degenerative processes. Furthermore, the results suggest that modifications of lipid composition during a plant's acclimation to adverse environments may determine the types of free radical reactions that occur due to stress.
Ultrasound in fatty acid chemistry: Synthesis of a 1‐pyrroline fatty acid ester isomer from methyl ricinoleate
Authors: Lie Ken Jie Marcel S. F. , Syed‐Rahmatullah M. S. K. , Lam C. K. , Kalluri P.
Published: December 2006

A novel 1‐pyrroline fatty acid ester isomer [viz. 8‐(5‐hexyl‐1‐pyrrolin‐2‐yl)octanoate] has been synthesized from methyl ricinoleate by two routes with an overall yield of 42 and 30%, respectively. Most of the reactions are carried out under concomitant ultrasonic irradiation (20 KHz,ca. 53 watts/cm2). Under such a reaction condition, the reaction time is considerably shortened, and product yields are high. Dehydrobromination under concomitant ultrasonic irradiation of methyl 9,10‐dibromo‐12‐hydroxyoctadecanoate with KOH in EtOH furnishes methyl 12‐hydroxy‐9‐octadecynoate (66%) within 15 min. Hydration of the latter under ultrasound with mercury(II)acetate in aqueous tetrahydrofuran yields exclusively methyl 12‐hydroxy‐9‐oxo‐octadecanoate (95%) in 30 min. The hydroxy group in the latter compound is transformed to the azido functionvia the mesylate, and treatment of the azido‐oxo intermediate (methyl 12‐azido‐9‐oxooctadecanoate) with Ph3P under ultrasonic irradiation furnishes the requisite 1‐pyrroline fatty acid ester (77%). The same azido‐oxo intermediate has also been obtained by the oxidation of methyl 12‐azido‐9‐cis‐octadecenoate using benzoquinone and a catalytic amount of Pd(II)chloride in aqueous tetrahydrofuran under concomitant ultrasonic irradiation (90 min) to give the product in 45% yield. The latter reaction does not take place even under prolonged silent stirring of the reaction mixture.
An addition compound of oxidized tocopherol and linoleic acid
Authors: Porter W. L. , Levasseur L. A. , Henick A. S.
Published: December 2006

There is evidence that an addition compound of oxidizeddl‐alpha‐tocopherol and linoleic acid is formed when the components are absorbed in mixed monolayer on silica gel at a molecular ratio of 1∶20, and subjected to heating in air at 80C. A relatively nonpolar tocopheryl quinone is also formed in smaller amounts. These are the major tocopherol oxidation products isolated in this system and do not correspond to any known to the authors. The addition compound has about the same mobility as linoleic acid in most thin layer chromatography (TLC) and chromatographic systems, but can be isolated by successive chromatography on silica and gel filtration on Sephadex LH‐20. It yields a single spot in TLC in several systems. The elemental analysis is reproducible and consistent with a simple addition compound of linoleic acid and bivalently oxidized tocopherol. The compound has a carboxyl group which can be esterified. The ester has about the same TLC mobility as methyl linoleate. The molecular weight of the ester is 722.6. The UV spectrum shows a single peak, 2maxETOH=3000 Å, E=4.74. The IR spectrum shows a very strong chroman ether band at 9.12 μ, a strong methyl band at 7.24 μ and carboxyl but no hydroxyl absorption. The NMR spectrum shows, in contrast to that of tocopherol, a reduction in aromatic methyl protons, a carboxyl proteon exchangeable with deuterium oxide, but no hydroxy proton. The compound does not reduce Emmerie‐Engel reagent prior to treatment with concentrated hydriodic acid, nor do the ether‐extractable products after such treatment. The present data are consistent with an addition product whose bridging group is a new chroman ring.
Free radicals, malonaldehyde and protein damage in lipid‐protein systems
Authors: Roubal W. T.
Published: December 2006

The free radical concentration in lipid‐protein mixtures with a low moisture content was monitored both during and after the time that the lipid actively absorbed oxygen. The data show that, in dry systems, the decay in radical content is followed by a rise in malonaldehyde protein fluorescence. Analysis of amino acid content at two distinctly different periods in the reaction substantiate the hypothesis that radicals and not aldehydes are a major cause of protein damage.
Cholesterol interference in analysis of fatty acid methyl esters
Authors: Hayes Lyle , Lowry Robert R. , Tinsley Ian J.
Published: December 2006

In the course of isolating and analyzing the fatty acid methyl esters (FAME) from steelhead trout (Salmo gairdneri) eggs and sac fry, a component was found on gas liquid chromatography to have a retention time longer than any characteristic polyunsaturated fatty acid previously encountered in trout. Subsequent purification and analysis demonstrated this component to be cholesterol. Thus, cholesterol and related compounds can interfere in the analysis of FAME when the methyl esters are prepared by transesterification.
Fatty acid metabolism and cell proliferation. III. Effect of prostaglandin biosynthesis either from exogenous fatty acid or endogenous fatty acid release with hydralazine
Authors: Morisaki N. , Lindsey J. A. , Milo G. E. , Cornwell D. G.
Published: December 2006

Primary cultures of smooth muscle cells were established from the medial layer of guinea pig aorta. Cells were seeded at from 40 to 80 cells per cm2 and cloned for 8 days. Media were analyzed for PGI2 (6‐keto‐PGF1α) using radioimmunoassay. Prostanoids were synthesized when cells were grown in media alone. Arachidonic acid stimulated prostanoid synthesis and promoted cell proliferation. Indomethacin blocked prostanoid synthesis and abolished the stimulatory effect of arachidonic acid on cell proliferation. Hydralazine stimulated fatty acid release and prostanoid synthesis in confluent cells. Hydralazine also stimulated prostanoid synthesis and promoted proliferation in growing cells. Indomethacin blocked prostanoid synthesis and abolished the stimulatory effect of hydralazine on cell proliferation.
Variations of fatty acid composition of erythrocyte and plasma lipids in the rat during the first period of life
Authors: Ciccoli L. , Comporti M.
Published: December 2006

The changes occurring in the fatty acid composition of the erythrocyte lipids during the first weeks of life were studied in the rat. The major changes consisted of a progressive decrease in oleic acid and a progressive increase in linoleic acid. A lower but significant increase in arachidonic acid was also observed. These changes are not related to variations in erythrocyte age; rather, they appear to be related to the age of the animal. Since somewhat similar changes were observed in the fatty acid composition of the major lipid classes of plasma during the first weeks of life, the possibility that these variations could account for the changes in the fatty acid composition of erythrocyte lipids was considered. Some support to this possibility was found in the results of experiments in which erythrocytes taken from 15‐day‐old rats were incubated with plasma taken from newborn rats. The changes in the fatty acid composition of erythrocytes and plasma lipids do not appear to be dependent on dietary lipids, since they occur during the suckling period, i.e., before the rats begin to ingest the pelleted diet which presents a fatty acid pattern completely different to that of the dams' milk.
Rapid qualitative analysis of polar and nonpolar lipids in a single sample using “Three‐Way” thin layer chromatography
Authors: Duck‐Chong Coral G. , Baker Gary J.
Published: December 2006

Plastic sheets, precoated with silica gel, are cut to give a square with a strip attached at the top right‐hand corner. Lipid extract is applied to the square portion, just below the strip, and chromatographed in a solvent which moves nonpolar lipids on to the strip, leaving polar lipids at the origin. The strip is cut off and separation of the lipids on the strip and the remaining square portion of the plate is completed by conventional one‐ or two‐dimensional chromatography, respectively. The application of this method and a multiple staining technique to the analysis of lipids in human bronchoalveolar lavage fluid is described.
Bile salt‐stimulated lipase in huma milk from 2 to 16 weeks postpartum
Authors: Brown Peter B. , Clark Richard M. , Hundrieser Kenneth E. , Ferris Ann M. , Jensen Robert G.
Published: December 2006

Our objectives were to determine the change in bile salt‐stimulated lipase (BSSL) activity in mature milk with time postpartum and to determine if BSSL activity was related to total lipid in the milk. Milk samples were collected from 12 mothers at 2,6,12 and 16 weeks postpartum. A significant (P<.05) decrease in BSSL activity with time was observed. The average values expressed as μmol free fatty acids released/min/ml milk were 5.3, 4.5, 4.1 and 3.6 at 2,6, 12 and 16 weeks postpartum. Total lipid in the milk increased significantly (P <.05) from 4.1 g/dl at 2 weeks to 5.4 g/dl at 16 weeks postpartum but was not significantly correlated with BSSL activity.
Sterols in chloroplasts: A description of two qualitatively distinct forms
Authors: Knights B. A.
Published: December 2006

Chloroplasts from eight plant species have been extracted sequentially with petroleum ether (PE) and acetone (A) and the extracts analyzed for sterols. Cholesterol was a component of all fractions analyzed but it was found that the A fraction of each species contained relatively much more cholesterol than the PE fraction. Other components of the PE sterol fractions were plant sterols typical of the species examined and were quantitatively markedly different from those in the corresponding A fractions. The yield of sterol from chloroplasts was found to be 0.02–0.03% and the ratio of the PE/A fractions to be 5∶1–19∶1.
Reaction products of tocopherols
Authors: Skinner W. A. , Parkhurst R. M.
Published: December 2006

Tocopherols readily undergo oxidation with a variety of oxidizing agents. Considerable effort has gone into isolation and identification of these various oxidation products. In many cases they can undergo further transformations upon treatment with various chemical reagents. This review will focus on the oxidation of α‐tocopherol and transformation of its oxidation products to new derivatives. Dimeric and trimeric oxidation products will not be covered. Early work on the oxidation of α‐tocopherol led to identification of α‐tocopherol quinone as an oxidation product formed by FeCl3 oxidation. Stronger oxidizing conditions with FeCl3 or oxidation with AgNO3 or HNO3 led to the orthoquinone and the hydroxy‐p‐quinone due to loss of one or two methyl groups from the aromatic ring. These early studies pointed out the unusual reactivity of the 5‐methyl group of α‐tocopherol. Oxidation of α‐tocopherol with benzoyl peroxide led to substitution of a benzoate on the 5‐methyl group. A similar reaction occurs when diasobisisobutyronitrile is used as the oxidizing agent. The oxidation of α‐tocopherol by tetrachloro‐o‐quinone in aqueous acetonitrile resulted in the formation of 9‐hydroxy‐α‐tocopherone. When FeCl3 was used as the oxidizing agent in the presence of α,α'‐bibyridyl in ethanol, 9‐ethoxy‐α‐tocopherone was formed. α‐Tocopherolquinone can be reduced with Zn−HOAc or by catalytic hydrogenation to the hydroquinone or reductively cyclized to α‐tocopherol with Zn−HBr. Reaction of α‐tocopherolquinone with acetyl chloride resulted in the 5‐chloromethyl‐6‐acetoxy derivative which has been converted to a variety of 5‐methylsubstituted derivatives. Reaction of α‐tocopherol with Br2 led to the 5‐bromomethyl derivative. When α‐tocopherolquinone was treated with hydrochloric, phosphoric, citric or tartaric acid, in the absence of oxygen, a disproportionation took place forming α‐tocopherol, α‐tocored and other oxidation products. An interesting isomerization of α‐tocored, the orthoquinone, occurs in the presence of aqueous HCl to yield the yellowp‐quinone with the chroman ring closed. The 5‐benzoyloxymethyl derivative upon treatment with HCl generateso‐quinone methide which can be trapped by reaction with tetracyanoethylene or dihydropyran. Treatment of the 5‐benzoyloxmethyl derivative with HCl in ethanol followed by sublimation yielded the 5‐aldehyde of α‐tocopherol. Recently, a series of phosphate derivatives of α‐tocopherol or its model, 2,2,5,7,8‐pentamethyl‐6‐chromanol, were synthesized. Tris (6‐acetoxy‐5‐methyleneoxy‐7,8‐dimethyltocol)phosphate, tris(2,2,5,7,8‐pentamethyl‐6‐chromanol)phosphate, 5‐hydroxymethyl‐2,2,7,8‐tetramethyl‐6‐chromanol phosphate and the cyclic 5‐methylenoxy‐2,2,7,8‐tetramethyl‐6‐chromanol phosphate, were prepared. These phosphates are of interest in view of a possible role of α‐tocopherol in oxidative phosphorylation.
Modern procedures for the analysis of tocopherols
Authors: Bunnell R. H.
Published: December 2006

The development of reliable assay methodology for the tocopherols has been an evolutionary process which has required over 40 years to reach its present state. Today the analyst has at his disposal a choice of reliable and accurate methods of analysis for the eight tocopherols now known to exist in nature. The general sequence of procedure and the precautions to be observed are described. After suitable extraction procedures and careful saponification techniques, the tocopherols in the nonsaponifiable fraction can be assayed by a variety of chromatographic procedures including paper, thin layer (TLC), column and gas liquid chromatography (GLC). The current methodology of these procedures is reviewed in some detail with special emphasis on the more frequently used TLC and GLC techniques. The earlier methods of GLC assay separated only the mono‐, di‐ and trimethylated tocopherols but methods are now available which provide separation of all the tocopherols. These developments were made possible by better columns and the use of derivatives of tocopherols. In addition to good separation, the GLC method is the most sensitive available for the quantitation of the tocopherols. Spectrophotometric measurements based on Emmerie Engel type reactions have been most frequently used for the final quantitative analysis of the tocopherols separated by paper, TLC, or column chromatography.
The composition of beef heart cardiolipins isolated by solvent and chromatographic fractionation
Authors: Courtade S. A. , McKibbin J. M.
Published: December 2006

A method is described for the isolation of cardiolipin from beef heart lipids by a single pass through a silica gel column. The isolated cardiolipin was free of neutral lipids and phospholipids and accounted for 10% of total phospholipid phosphorus. It was compared to commercial cardiolipins prepared by the Pang‐born method of selective precipitation. Analysis for fatty acids, glycerol and phosphorus revealed a molar ratio of 2∶1.5∶1 for both preparations, provided the fatty acid esters were assayed colorimetrically. If the fatty acids were determined by titration, the commercial cardiolipin had a molar ratio of fatty acid to phosphorus of 1.6, while ours remained at 2.0. Upon hydrolysis with acetic acid, the former yielded 76% water‐soluble phosphorus, the latter only 2%. Both cardiolipins contained over 90% C‐18 fatty acids, with our preparation containing 76% linoleate, the commercial preparation, 90%. After alkaline hydrolyses a component was isolated from the commercial cardiolipin which represented 15.5% of the total weight. It developed an interfering pigment in the fatty acid ester determination but has not been identified. After its removal analysis demonstrated three fatty acids per molecule of the commercial cardiolipin.
The biosynthesis of polyunsaturated fatty acids in plants
Authors: Gurr M. I.
Published: December 2006

This paper is a review of some of the work being done at the author's laboratory. The phospholipids and glycolipids of the alga,Chlorella vulgaris, have been implicated in fatty acid transformations such as chain elongation and desaturation. Labeling studies with [14C] acetate have shown that newly synthesized galactosyl glycerides have mainly saturated fatty acids. Subsequent to de novo synthesis, a series of alterations of fatty acid structure takes place within the same glycolipid molecules. The specific incorporation of [14C] oleic acid intoChlorella phosphatidyl choline provides a convenient model system for studying the lipid dependent desaturation of oleic to linoleic acid. The inhibitor of fatty acid desaturation, sterculic acid, only inhibits the conversion of oleate into linoleate if added before the precursor fatty acid has been incorporated into a complex lipid. Studies with isomeric monoenoic fatty acids have suggested that there are two enzymes which catalyze the formation of linoleic from oleic acid. One measures the position of the second double bond from the carboxyl group, the other, from the methyl end of the chain. The latter enzyme probably requires the complex lipid substrate.
Inhibition of fat cell lipolysis by low FFA to albumin ratios
Authors: Hubbard R. W. , Matthew W. T.
Published: December 2006

Epididymal fat cells isolated from chronically cold‐exposed rats were used to study the inhibition of lipolysis with albumin bound FFA. It was demonstrated that lipolysis becomes inhibited as the class 2 binding sites on albumin are filled and that 50% inhibition occurs at free fatty acid (FFA) to albumin ratios between 4.6 and 4.0. Experiments with dibutyryl adenosine cyclic phosphate suggest that this is an effect on the fat cell lipases rather than the lipase activating system or phosphodiesterase. The results indicate that reesterification proceeds as a relatively constant percentage of the rate of lipolysis and, therefore, in the absence of exogenous FFA, conditions that reduce lipolysis reduce reesterification. On the other hand, high rates of reesterification can apparently be stimulated even when the class 1 binding sites on albumin are not filled.
Awareness of physicians in Jordan about the treatment of high blood pressure according to the seventh report of the Joint National Committee (JNC VII)
Authors: Al-Azzam Sayer Ibrahim , Najjar Rula Basem , Khader Yousef Saleh
Published: December 2006

Background

Control of blood pressure remains suboptimal worldwide. High rates of undiagnosed and untreated hypertensive patients raise the need of searching for the basis of this situation among prescribing physicians.

Aim

To evaluate the awareness of medical residents and practicing physicians in Jordan about the treatment of high blood pressure according to the seventh report of the Joint National Committee (JNC VII).

Method

A written questionnaire was distributed to 200 physicians from different areas of Jordan during the period from November 2005 till February 2006. Recruitment of physicians in this study was in general, military, private hospitals and in clinics. A rigorously developed questionnaire on changes seen in JNC VII, target blood pressure goals, and the treatment of high blood pressure options was administered by trained medical personnel.

Results

One hundred and forty five physicians (72.5%) consented to complete the questionnaire. The practices of recent graduates from medical school were not better than those of older graduates. As a general rule, physicians in Jordan under treat high blood pressure.

Conclusion

Our findings highlight the need for the revision of the teaching curricula in medical schools with regard to the management of hypertension, as well as the initiation of a widespread and intensive continuing medical education for all physicians involved in the management of patients with hypertension. Particular efforts are needed to encourage the use of low-cost thiazides and the use of angiotension converting enzyme inhibitors in heart failure patients and other compelling indications.
Phenylpropanoid glycosyltransferases from osage orange (Maclura pomifera) fruit
Authors: Tian Li , Blount Jack W. , Dixon Richard A.
Published: December 2006

Flavonoids and isoflavonoids are well known for their beneficial effects on human health and their anti‐insect and anti‐microbial activities in plants. Osage orange fruit is rich in prenylated isoflavones and dihydrokaempferol and its glucoside. Four glycosyltransferases were identified from a collection of osage orange fruit expressed sequence tags. Biochemical characterization suggested that the glycosyltransferase UGT75L4 might be responsible for glucosylation of dihydrokaempferol in vivo, although this enzyme exhibited broad substrate recognition toward isoflavonoids and flavonoids in vitro. UGT88A4 was active on coumarin substrates. Identification of highly active phenylpropanoid glycosyltransferases will facilitate the metabolic engineering of glycosylated natural products in plants.
Pseudomonas aeruginosa quorum sensing molecule N‐(3 oxododecanoyl)‐l‐homoserine lactone disrupts epithelial barrier integrity of Caco‐2 cells
Authors: Vikström Elena , Tafazoli Farideh , Magnusson Karl-Eric
Published: December 2006

Acyl‐homoserine lactone (HSL) quorum sensing molecules play an important role in regulation of virulence gene expression in Pseudomonas aeruginosa. Here, we show that 3O–C12–HSL can disrupt barrier integrity in human epithelial Caco‐2 cells as evidenced by decreased transepithelial electrical resistance (TER), increased paracellular flux, reduction in the expression and distribution of ZO‐1 and occludin, and reorganization of F‐actin. P. aeruginosa 3O–C12–HSL activate p38 and p42/44 kinases, and inhibition of these kinases partly prevented 3O–C12–HSL‐induced changes in TER, paracellular flux and expression of occludin and ZO‐1. These findings demonstrate that P. aeruginosa 3O–C12–HSL can modulate tight junction integrity of Caco‐2 cells.
Photodamaged D1 protein is degraded in Arabidopsis mutants lacking the Deg2 protease
Authors: Huesgen Pitter F. , Schuhmann Holger , Adamska Iwona
Published: December 2006

In plants exposed to high irradiances of visible light, the D1 protein in the reaction center of photosystem II is oxidatively damaged and rapidly degraded. Earlier work in our laboratory showed that the serine protease Deg2 performs the primary cleavage of photodamaged D1 protein in vitro. Here, we demonstrate that the rate of D1 protein degradation under light stress conditions in Arabidopsis mutants lacking the Deg2 protease is similar to those in wild‐type plants. Therefore, we propose that several redundant D1 protein degradation pathways might exist in vivo.
Relationships of Drosophila melanogaster RECQ5/QE to cell‐cycle progression and DNA damage
Authors: Nakayama Minoru , Maruyama Sayako , Kanda Hiroshi , Ohkita Noriko , Nakano Katsunori , Ito Fumiaki , Kawasaki Katsumi
Published: December 2006

Members of the RecQ family of DNA helicases are involved in the cellular response to DNA damage and are regulated in the cell‐cycle. However, little is known about RecQ5, one of these members. The level of RECQ5/QE, Drosophila melanogaster RecQ5, was increased after the exposure of cultured cells to methyl‐methanesulfonate. Transgenic flies that overexpressed RECQ5/QE in their developing eye primordia showed mild roughening of the ommatidial lattice. DNA‐damaging agents and the mei‐41 mutation enhanced the phenotype caused by RECQ5/QE overexpression. Overexpression of RECQ5/QE perturbed the progression of the cell‐cycle in response to DNA damage in the eye imaginal discs. These results suggest that RECQ5/QE interacts with components of the cell‐cycle during its progression in response to DNA damage.
Autocrine anti‐apoptotic and proliferative effects of insulin in pancreatic β‐cells
Authors: Muller Dany , Jones Peter M. , Persaud Shanta J.
Published: December 2006

Insulin and glucose inhibited apoptosis in the MIN6 insulin‐secreting cell line. The protective effect of 25 mM glucose was prevented by an anti‐insulin antibody and this antibody‐induced increase in apoptosis was reversed by the presence of excess insulin. Glucose stimulated MIN6 cell proliferation and this was inhibited by blockade of insulin secretion, by an anti‐insulin antibody and by phosphatidylinositol‐3 kinase (PI‐3K) inhibition. Furthermore, MIN6 cell proliferation was stimulated by depolarising concentrations of KCl and by insulin itself. These data indicate that insulin secreted by β‐cells in response to elevated glucose exerts autocrine effects to protect against apoptosis and stimulate proliferation, and suggest that the insulin signalling cascade, through the PI‐3K pathway, may be an effective means of maintaining β‐cell mass in diabetes.
Single and cell population respiratory oscillations in yeast: A 2‐photon scanning laser microscopy study
Authors: Aon Miguel A. , Cortassa Sonia , Lemar Katey M. , Hayes Anthony J. , Lloyd David
Published: December 2006

Two‐photon scanning laser and confocal microscopies were used to image metabolic dynamics of single or cell populations of Saccharomyces cerevisiae strain 28033. Autofluorescence of reduced nicotinamide nucleotides, and mitochondrial membrane potential (ΔΨm), were simultaneously monitored. Spontaneous, large‐scale synchronized oscillations of NAD(P)H and ΔΨm throughout the entire population of yeasts occurred under perfusion with aerated buffer in a continuous single‐layered film of organisms. These oscillations stopped in the absence of perfusion and the intracellular NAD(P)H pool became reduced. Individual mitochondria within a single yeast also showed in‐phase synchronous responses with the cell population, in both tetramethylrhodamine ethyl ester (or tetramethylrhodamine methyl ester) and autofluorescence. A single, localized, laser flash also triggered mitochondrial oscillations in single cells suggesting that the mitochondrion may behave as an autonomous oscillator. We conclude that spontaneous oscillations of S. cerevisiae mitochondrial redox states and ΔΨm occur within individual yeasts, and synchrony of populations of organisms indicates the operation of an efficient system of cell–cell interaction to produce concerted metabolic multicellular behaviour on the minute time scale in both cases.
Epac‐ and Rap‐independent ERK1/2 phosphorylation induced by Gs‐coupled receptor stimulation in HEK293 cells
Authors: Norum Jens Henrik , Dawood Hoda , Mattingly Raymond R. , Sandnes Dagny , Levy Finn Olav
Published: December 2006

Serotonin activates Ras and Ras‐dependent ERK1/2 phosphorylation in HEK293 cells expressing Gs‐coupled 5‐HT4 or 5‐HT7 serotonin receptors through unknown mechanisms. Both Epac/Rap‐dependent and ‐independent pathways for Ras‐dependent ERK1/2 activation have been suggested. Epac overexpression or Epac‐specific 8‐CPT‐2′‐O‐Me‐cAMP did not cause ERK1/2 phosphorylation, despite Rap activation. The data did not support a role for PLCε or DAG‐dependent Ras GEFs of the Ras‐GRP family in Ras‐dependent ERK1/2 phosphorylation. However, serotonin stimulated phosphorylation of endogenous and recombinant Ras‐GRF1, increased [Ca2+]i and caused Ca2+‐ and calmodulin‐dependent ERK1/2 phosphorylation. Different signalling pathways seem to be utilised by Gs‐coupled receptors in various isolates of HEK293 cells.
Reconstructing the response of C3 and C4 plants to decadal-scale climate change during the late Pleistocene in Southern Illinois using isotopic analyses of calcified rootlets
Authors: Wang Hong , Greenberg Sallie E.
Published: December 2006

The δ13C and δ18O values of well-preserved carbonate rhizoliths (CRs) provide detailed insights into changes in the abundance of C3 and C4 plants in response to approximately decadal-scale changes in growing-season climate. We performed stable isotope analyses on 35–40 CRs sampled at 1-cm intervals from an 18-cm-thick paleosol formed in southern Illinois during Wisconsin interstadial 2. Minimum δ13C values show little variation with depth, whereas maximum values vary dramatically, and average values show noticeable variability; maximum δ18O values vary less than the minimum δ18O values. These findings indicate that a diverse and stable C3 flora with a limited number of C4 grass species prevailed during this interval, and suggest that the maximum growing-season temperatures were relatively stable, but minimum growing-season temperatures varied considerably. Two general patterns characterize the relationships between the δ13C and δ18O values obtained from the 1-cm samples. In some cases, low δ13C values correspond to low δ18O values and high δ13C values correspond to high δ18O values, suggesting that cooler growing-season temperatures favored C3 and warmer growing-season temperatures favored C4 plants. In other cases, low δ13C values correspond to high δ18O values, likely suggesting that wetter growing-season conditions were favorable to C3 plants. The high density of well-preserved CRs in this paleosol provides a unique opportunity to study detailed ecological responses to high-resolution variability in growing-season climate.
Proton cyclotron waves at Mars: Exosphere structure and evidence for a fast neutral disk
Authors: Wei H. Y. , Russell C. T.
Published: December 2006

Mars is an unmagnetized planet whose hydrogen exosphere extends into the solar wind, creating proton cyclotron waves. Mars Global Surveyor data reveal the occurrence of waves to be extensive and often intermittent at large distance, indicating that the exosphere is time varying or non‐spherical. When the region of wave occurrence is examined in a magnetic‐electric coordinate system, a strong asymmetry in the occurrence of these waves is seen in the direction of the interplanetary electric field. The extensive, yet asymmetric and intermittent, occurrence of waves can be understood if, after protons are first picked up near Mars, the ions are neutralized by charge exchange and transported across field lines to distant regions, allowing the pickup process to extend far from Mars on only one side of the planet. Thus the exosphere of Mars appears to extend in a disk of fast hydrogen atoms both downstream and to the side of Mars in the direction of the interplanetary electric field.
Calculated and observed climate change in the thermosphere, and a prediction for solar cycle 24
Authors: Qian Liying , Roble Raymond G. , Solomon Stanley C. , Kane Timothy J.
Published: December 2006

The long‐term change of thermospheric neutral density has been investigated using satellite drag measurements and through sensitivity studies using upper atmosphere general circulation models. The magnitude of the change has been quantified in both approaches, and the source of the secular change attributed to the concentration changes of greenhouse gases. In this study, we use CO2 concentration measured at Mauna Loa Observatory and solar variation based on a proxy model to calculate the secular change of thermosphere neutral density for the last three decades, using a global mean upper atmosphere model. Our results show that the average density decrease at 400 km from 1970 to 2000 is 1.7% per decade. To quantify the impact of solar activity on the secular change of neutral density, we also calculated the long‐term density change under solar minimum and solar maximum conditions for the same time period. The average trends at 350 km and 450 km are 2.2% per decade and 2.9% per decade for solar minimum conditions, while at solar maximum, they are 0.7% per decade and 0.8% per decade, respectively. These model results are compared to estimates of thermosphere density change derived from satellite drag observations, showing good agreement. In addition, based on a recent forecast of the intensity of solar cycle 24, we predict that the long‐term change of thermospheric neutral density from 2006 to the end of solar cycle 24 will be ∼2.7% per decade at 400 km.
Magnetically controlled structures in the ionosphere of Mars
Authors: Duru F. , Gurnett D. A. , Averkamp T. F. , Kirchner D. L. , Huff R. L. , Persoon A. M. , Plaut J. J. , Picardi G.
Published: December 2006

The ionospheric sounding data obtained by the MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) instrument on the Mars Express spacecraft show that the dayside ionosphere has considerable structure over regions of strong crustal magnetic fields. This structure is typically seen as a hyperbola‐shaped trace in a display of echo intensity versus apparent altitude and time. The hyperbola shapes are consistent with oblique reflections from regions of enhanced electron density that are fixed with respect to Mars. Comparisons with the Cain et al. (2003) model for the crustal magnetic field of Mars show that the apexes of the hyperbolas, which identify the closest approach to the regions of enhanced electron density, usually coincide with regions where the crustal magnetic field is strong and nearly vertical. The electron density enhancements, which extend as much as 50 km above the surrounding ionosphere, are believed to arise from increases in the scale height of the ionosphere, possibly due to heating of the ionosphere by solar wind electrons that reach the base of the ionosphere along the nearly vertical (open) magnetic field lines. Statistical analyses of the apparent altitudes of the apexes of the hyperbolas, as well as analyses of repeated passes over the same region, indicate that the electron density enhancements usually consist of horizontal cylinder‐like structures rather than isolated hemispherical structures. In many cases the axes of the cylindrical density structures are aligned with the symmetry axes of adjacent cylindrical magnetic field structures with opposite polarity.
A time‐dependent model of the Earth's magnetic field and its secular variation for the period 1980–2000
Authors: Wardinski I. , Holme R.
Published: December 2006

This study presents an investigation and description of the secular variation of the Earth's magnetic field between 1980 and 2000. A time‐dependent model, C3FM (Continuous Covariant Constrained endpoints Field Model), of the main field and its secular variation between 1980 and 2000 is developed, with Gauss coefficients expanded in time on a basis of cubic B splines. This model is constrained to fit field models from high‐quality vector measurements of Magsat in 1980 and Ørsted in 2000 and to fit both magnetic observatory and repeat station secular variation estimates for the period in between. These secular variation estimates (first time derivatives) are derived from observatories monthly or annual means and repeat station data in order to reduce the contributions of crustal noise, annual, and semiannual variation. On average, the model input consists secular variation estimates of the X, Y, and Z components at 130 locations per month. Treatment of covariance between the different components allows a higher temporal sensitivity of the model, due to the exclusion of some external field variation. The model is computed up to degree and order 15. The model is a useful extension of the hitherto existing time‐dependent description of the secular variation, GUFM which describes the secular variation until 1990. It reveals a short‐term secular variation on subdecadal timescale and has a higher spatial resolution, than previously resolved. The model is also valuable to test the frozen flux hypothesis and to link features of the radial field at the core‐mantle boundary to the geodynamo.
Form drag in rivers due to small‐scale natural topographic features: 1. Regular sequences
Authors: Kean Jason W. , Smith J. Dungan
Published: December 2006

Small‐scale topographic features are commonly found on the boundaries of natural rivers, streams, and floodplains. A simple method for determining the form drag on these features is presented, and the results of this model are compared to laboratory measurements. The roughness elements are modeled as Gaussian‐shaped features defined in terms of three parameters: a protrusion height, H; a streamwise length scale, σ; and a spacing between crests, λ. This shape is shown to be a good approximation to a wide variety of natural topographic bank features. The form drag on an individual roughness element embedded in a series of identical elements is determined using the drag coefficient of the individual element and a reference velocity that includes the effects of roughness elements further upstream. In addition to calculating the drag on each element, the model determines the spatially averaged total stress, skin friction stress, and roughness height of the boundary. The effects of bank roughness on patterns of velocity and boundary shear stress are determined by combining the form drag model with a channel flow model. The combined model shows that drag on small‐scale topographic features substantially alters the near‐bank flow field. These methods can be used to improve predictions of flow resistance in rivers and to form the basis for fully predictive (no empirically adjusted parameters) channel flow models. They also provide a foundation for calculating the near‐bank boundary shear stress fields necessary for determining rates of sediment transport and lateral erosion.
Form drag in rivers due to small‐scale natural topographic features: 2. Irregular sequences
Authors: Kean Jason W. , Smith J. Dungan
Published: December 2006

The size, shape, and spacing of small‐scale topographic features found on the boundaries of natural streams, rivers, and floodplains can be quite variable. Consequently, a procedure for determining the form drag on irregular sequences of different‐sized topographic features is essential for calculating near‐boundary flows and sediment transport. A method for carrying out such calculations is developed in this paper. This method builds on the work of Kean and Smith (2006), which describes the flow field for the simpler case of a regular sequence of identical topographic features. Both approaches model topographic features as two‐dimensional elements with Gaussian‐shaped cross sections defined in terms of three parameters. Field measurements of bank topography are used to show that (1) the magnitude of these shape parameters can vary greatly between adjacent topographic features and (2) the variability of these shape parameters follows a lognormal distribution. Simulations using an irregular set of topographic roughness elements show that the drag on an individual element is primarily controlled by the size and shape of the feature immediately upstream and that the spatial average of the boundary shear stress over a large set of randomly ordered elements is relatively insensitive to the sequence of the elements. In addition, a method to transform the topography of irregular surfaces into an equivalently rough surface of regularly spaced, identical topographic elements also is given. The methods described in this paper can be used to improve predictions of flow resistance in rivers as well as quantify bank roughness.