bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of plasma lipoproteins on the production of superoxide anion by human polymorphonuclear leukocytes in vitro
Authors: Couderc Rémy , Bonneau Christine , Tissot Michéle , Bailleul Sophie , Roch‐Arveiller Monique , Giroud Jean Paul
Published: December 2008

Polymorphonuclear leukocytes (PMN) generate highly reactive oxygen derived free radicals that may cause lipoprotein lipid oxidation and so contribute to the pathogenesis of atherosclerosis. On the other hand it has been shown that lipoproteins can alter cell functions in vitro. We therefore studied the effects of atherogenic lipoproteins, VLDL and LDL, on the production of superoxide anion by human PMN in the presence or absence of formyl‐methionyl‐leucyl‐phenylalanine (fMLP). VLDL and LDL stimulate PMN superoxide production and potentialize PMN stimulation by fMLP. The lipid moiety of the lipoproteins might be mainly involved in these effects. The binding of radio‐labelled fMLP to its specific membrane receptor was significantly enhanced in the presence of VLDL and only slightly in the presence of LDL. The study of the signal transduction suggests that modulation of phospholipase D and A2 activities could be involved in the modification by LDL of PMN response to fMLP.
Breakdown of oxidized proteins as a part of secondary antioxidant defenses in mammalian cells
Authors: Grune T. , Davies K. J. A.
Published: December 2008

The degradation of oxidized proteins is an essential part of antioxidant defenses against free radical attack. Selective degradation of oxidatively damaged proteins allows proteolytic systems to function directly in the removal of useless cellular debris and therefore prevent the accumulation of potentially toxic fragments or large aggregates of cross‐linked proteins.

The degradation of oxidized proteins in dividing mammalian cells after hydrogen peroxide treatment has been demonstrated. Cells are able to increase proteolysis rates after treatment with moderate levels of oxidants. The role of proteasome in the removal of oxidized proteins has been demonstrated by treatment of cells with an anti‐sense oligodesoxynucleotide to the proteasome C2 subunit gene. This treatment decreases the proteasome content of the cells and prevents increased proteolysis rates after hydrogen peroxide treatment. Thus proteasome clearly plays a role in the removal of oxidized proteins.

As part of antioxidant defenses the proteasome provides a second line of defense against the numerous radicals and oxidants which contact cells during their lifetime. The degradation of oxidatively damaged proteins enables cells to recover from a moderate oxidant attack.
A non‐radioactive and two radioactive assays for selenophosphate synthetase activity
Authors: Liu Song‐Yuan , Stadtman Thressa C.
Published: December 2008

Selenophosphate synthetase catalyzes the formation of monoselenophosphate (SePO3−3) from ATP and selenide (reaction 1).

In one assay frequently used, [8‐14C]AMP formation from [8‐14C]ATP is estimated after separation of the nucleotides by thin‐layer chromatography. An alternative non‐radioactive assay in which the AMP product is estimated using AMP deaminase is described. The highly oxygen‐labile selenophosphate product can be estimated in an assay employing [γ‐32P]ATP. The 32P‐labeled selenophosphate is converted to [32P]orthophosphate by treatment with iodine and estimated after removal of residual [32P]ATP on charcoal.
cDNA and deduced polypeptide sequence of a mouse selenoprotein P
Authors: Steinert Peter , Ahrens Marion , Gross Gerhard , Flohé Leopold
Published: December 2008

An 11‐day embryonic Swiss Webster/NIH mouse cDNA library was screened with a partial murine selenoprotein P cDNA probe and a murine selenoprotein‐P‐type cDNA

The accession number of the nucleic acid sequence data for murine selenoprotein P in the EMBL Data Library is X99807.

clone of 2075 bp lenght was obtained. The clone contained a 5′‐leader sequence of 132 bp length, the selenoprotein P coding frame, and 803 base pairs in the 3′ untranslated region. Alignment and RNA folding studies revealed the presence of two well conserved selenocysteine inserting motifs in the 3′ flanking region. The deduced polypeptide sequence comprises 380 residues including ten selenocysteines. Identical amino acid residues in homologous positions are 86%, 71%, and 64% when compared to the previously reported selenoprotein P sequences of rat, man, and cattle, respectively. The comparatively low similarity between the selenoprotein P sequences reported so far leaves open the question whether they belong to the same molecular clade.
Lipoic acid increases de novo synthesis of cellular glutathione by improving cystine utilization
Authors: Han Derick , Handelman Garry , Marcocci Lucia , Sen Chandan K. , Roy Sashwati , Kobuchi Hirotsugu , Tritschler Hans J. , Flohé Leopold , Packer Lester
Published: December 2008

Lipoic acid (thiotic acid) is being used as a dietary supplement, and as a therapeutic agent, and is reported to have beneficial effects in disorders associated with oxidative stress, but its mechanism of action remains unclear. We present evidence that lipoic acid induces a substantial increase in cellular reduced glutathione in cultured human Jurkat T cells, human erythrocytes, C6 glial cells, NB41A3 neuroblastoma cells, and peripheral blood lymphocytes. The effect depends on metabolic reduction of lipoic acid to dihydrolipoic acid. Dihydrolipoic acid is released into the culture medium where it reduces cystine. Cysteine thus formed is readily taken up by the neutral amino acid transport system and utilized for glutathione synthesis. By this mechanism lipoic acid enables cystine to bypass the χ‐c transport system, which is weakly expressed in lymphocytes and inhibited by glutamate. Thereby lipoic acid enables the key enzyme of glutathione synthesis, γ‐glutamylcysteine synthetase, which is regulated by uptake‐limited cysteine supply, to work at optimum conditions. Flow cytometric analysis of freshly prepared human peripheral blood lymphocytes, using monobromobimane labeling of cellular thiols, reveals that lipoic acid acts mainly to normalize a subpopulation of cells severely compromised in thiol status rather than to increase thiol content beyond physiological levels. Hence lipoic acid may have clinical relevance in restoration of severely glutathione deficient cells.
Evidence for a functional relevance of the selenocysteine residue in mammalian thioredoxin reductase
Authors: Marcocci Lucia , Flohé Leopold , Packer Lester
Published: December 2008

Human thioredoxin reductase was recently shown to contain a TGA encoded selenocysteine residue at the penultimate position of its amino acid chain. Depending on the availability of selenium during biosynthesis, an authentic selenocysteine‐containing or a selenium‐free enzyme truncated at the penultimate position is expected to be formed. Correspondingly, the enzymatic activity should be altered by selenium restriction, if the selenocysteine residue is functionally important. In order to check the catalytic role of the selenocysteine residue, four different human cell lines were grown in selenium deficient media or with adequate selenium supplementation (40 nM sodium selenite) and thioredoxin reductase activity was measured as NADPH‐dependent DTNB reduction or thioredoxin‐mediated insulin reduction. Thioredoxin reductase activities, like glutathione peroxidase activities, were consistently higher in selenium supplemented cells, whereas glutathione reductase activity was not affected by the selenium. The dose‐response was similar for thioredoxin reductase and glutathione peroxidase, but the recovery of glutathione peroxidase activity upon selenium supplementation was faster than with thioredoxin reductase. Also the increase of glutathione peroxidase activities was substantially higher than that of thioredoxin reductase (400–1200% versus a maximum of 250%). These observations clearly indicate a catalytic role of the selenocysteine residue in the thioredoxin reductase, but suggest either the existence of a selenium‐unresponsive isoenzyme or a residual disulfide reductase activity in the selenium‐free truncated protein made under conditions of selenium deficiency.
Prevention of diabetes‐induced abnormal retinal blood flow by treatment with d‐α‐tocopherol
Authors: Kunisaki Makoto , Bursell Sven‐Erik , Umeda Fumio , Nawata Hajime , King George L.
Published: December 2008

Hyperglycemia in diabetes mellitus has been shown to activate diacylglycerol (DAG)‐protein kinase C (PKC) pathway in the vascular tissues, possibly altering vascular function. We have characterized the effects of vitamin E (d‐α‐tocopherol) on activation of PKC and DAG levels in retinal tissues of diabetic rats, and correlated its effects to retinal hemodynamics using video‐based fluorescein angiography (VFA). Comparing streptozotocin‐induced diabetic rats to controls, membranous PKC specific activities were increased by 71% (p< 0.05). Western blot analysis showed that the membranous PKC βII isoform was significantly increased by 133± 45% (p< 0.05). Intraperitoneal injection of d‐α‐tocopherol (40 mg/kg) every other day prevented the increases in membranous PKC specific activity and PKC β II protein shown by immunoblots. Similar to PKC activities, total DAG levels were increased in the retina and were normalized by d‐α‐tocopherol treatment. Physiologically, abnormalities of retinal blood hemodynamics, as measured using VFA, which previously have been reported to be associated with increases of DAG and PKC levels in the diabetic rats, were prevented by d‐α‐tocopherol treatment in diabetic rats. The direct effect of d‐α‐tocopherol on total DAG and [3H]‐palmitate incorporation into DAG were also examined using cultured bovine retinal endothelial cells (REC). Exposure of REC to 22 mM glucose for three days increased total DAG and [3H]‐palmitate labeled DAG levels by 35± 8% and 50± 8%, respectively (p< 0.05). The presence of d‐α‐tocopherol (50 μg/ml) prevented the increase of both total DAG and [3H]‐palmitate labeled DAG levels in cells exposed to 22 mM glucose.

These findings suggested that the mechanism of the d‐α‐tocopherol's effect appears to be mediated by the normalization of the hyperglycemia‐induced activation of the DAG‐PKC pathway which leads to the normalization of abnormal retinal blood flow seen in diabetes mellitus.
The role of vitamin E in T‐cell differentiation and the decrease of cellular immunity with aging
Authors: Moriguchi Satoru
Published: December 2008

The purpose of this study is to investigate the effects of vitamin E on both the decrease of cellular immunity with aging (Section 2) and the differentiation of T‐cells in thymus (Section 3). In Section 2, spontaneously hypertensive rats (SHR) as a model for aging were used in this experiment and fed regular (50 IU/kg diet) or a high vitamin E (500 IU/kg diet) diet for 6 weeks. At 12 weeks old, they were killed and assayed. Although proliferation of thymic lymphocytes was significantly decreased in SHR fed the regular diet compared to that of Wistar Kyoto rats (WKY) fed the same diet, the high vitamin E diet induced higher proliferation of thymic lymphocytes in SHR, which was almost the same as that of WKY fed the regular diet. In addition, the expressions of both CD4 and CD8 antigens on CD4+CD8+ T‐cells were also decreased in SHR, which was significantly improved by a high vitamin E diet. These results suggest that a high vitamin E diet enhances thymic lymphocyte proliferation through increased T‐cell differentiation in the thymus. Then, the effect of vitamin E on T‐cell differentiation in the thymus was investigated by using male Fisher rats. Rats were divided into three groups; vitamin E‐free, regular and high vitamin E groups and fed a diet containing various levels of vitamin E (0, 50 and 500 IU/kg diet) for 7 weeks. Although the proportions of CD4+CD8‐ and CD4‐CD8+ T‐cells in thymocytes were significantly greater in the high vitamin E group, the proportion of CD4+CD88‐ T‐cells inversely decreased in the vitamin E‐free group compared to that of the regular group. We have tried to investigate the mechanism on the increased T‐cell differentiation in the thymus of rats fed the high vitamin E diet through cytokine production, thymic epithelial cell (TEC) and macrophage functions. As their results, we have found that vitamin E enhances T‐cell differentiation through the increase of not macrophage but TEC function in the thymus, which is associated with the increased binding capacity of TEC to immature T‐cells via increased expression of the adhesion molecule, ICAM‐1. These results suggest that vitamin E is a potent nutrient for promoting health in the aged via the improvement of cellular immunity decreased with aging.
Can antioxidant supplementation slow the aging process?
Authors: Yu Byung P. , Kang Chang‐Mo , Han Jung‐Soon , Kim Dong Soo
Published: December 2008

The oxidative stress theory of aging is well supported by accumulated evidence from various aging intervention studies. Early antioxidant supplementation studies indicate life span extensions by antioxidant feeding in various experimental organisms. Data collected under tightly controlled conditions show that the feeding of 2‐mercaptoethanol (0.25%) effectively prolonged both the median and maximum life spans of mice. Evidence has been obtained showing dietary vitamin E to protect against oxidative damage to DNA in human lymphocytes and white blood cells. Other clear evidence of vitamin E's protective effect has been seen in its suppressive action of LDL oxidation both in vitro and in vivo. New evidence on the physiological roles of antioxidants, in addition to their well‐known role as free radical scavengers, is emerging from recent research. For instance, the beneficial effect of vitamin E in improving glucose transport and the insulin sensitivity and its putative role as a regulator of cell proliferation should open new research dimensions. This presentation will review some of the anti‐aging aspects of dietary antioxidant supplementation, as well as the potential problems of its long‐term administration that stem from our lack of knowledge about free radical metabolism and the regulation of endogenous defense mechanisms.
Vitamins E plus C and interacting conutrients required for optimal health
Authors: Fred Gey K.
Published: December 2008

Antioxidants are crucial components of fruit/vegetable‐rich diets preventing cardiovascular disease (CVD) and cancer:

—plasma vitamins C, E, carotenoids from diet correlate prevalence of CVD and cancer inversely, low levels predict an increased risk of individuals which is potentiated by combined inadequacy (e.g., vitamins C+E, C+carotene, A+carotene);

—self‐prescribed rectification of vitamins C and E at adequacy of other micronutrients reduce forthcoming CVD, of vitamins A, C, E, carotene and conutrients also cancer;

—randomized exclusive supplementation of β‐carotene±vitamin A or E lack benefits except prostate cancer reduction by vitamin E, and overall cancer reduction by selenium;

—randomized intervention with synchronous rectification of vitamins A+C+E+B+minerals reduces CVD and counteracts precancerous lesions;

—high vitamin E supplements reveal potentials in secondary CVD prevention.

Plasma values desirable for primary prevention: ≥30μmol/l lipid‐standardized vitamin E (α‐tocopherol/cholesterol ≥5.0μmol/mmol); ≥50μmol/l vitamin C aiming at vitamin C/vitamin E ratio >1.3–1.5; ≥0.4μmol/l β‐ (≥0.5μmol/l α+β‐) carotene.

Conclusions:

—in CVD vitamin E acts as first risk discriminator, vitamin C as second one;

—optimal health requires synchronously optimized vitamins C+E, A, carotenoids and vegetable conutrients.
Knockout of cellular glutathione peroxidase affects selenium‐dependent parameters similarly in mice fed adequate and excessive dietary selenium
Authors: Cheng Wen‐Hsing , Combs Gerald F. , Lei Xin Gen
Published: December 2008

This study was to determine whether or not effects of the cellular glutathione peroxidase (GPX1) knockout on several Se‐dependent parameters in mice were tissue, dietary Se concentration, and selenoprotein specific. A 2×3 factorial experiment was conducted with 18 GPX1 knockout mice [GPX1(‐)] and 18 controls (3 weeks old, half males and females). These mice were fed a torula yeast diet supplemented with all‐rac‐α‐tocopheryl acetate (50 mg/kg of feed) and Se (sodium selenite) at 0, 0.5, or 3.0 mg/kg of feed for 6 weeks. Both kidney GPX1 mRNA levels and liver, kidney, lung, and testis total GPX activities, assayed using hydrogen peroxide, were affected (p< 0.001) by the GPX1 knockout and dietary Se concentrations, whereas kidney extracellular or plasma GPX (GPX3) mRNA levels and phospholipid hydroperoxide GPX (GPX4) activities in the four tissues were affected (p< 0.001) by only dietary Se concentrations. Total GPX activity in testis was reduced approximately 90% (p< 0.01) by the GPX1 knockout. Neither the GPX1 knockout nor the dietary Se concentrations affected mRNA levels of GPX4 in testis or selenoprotein P in kidney. Total liver Se concentrations were not different between the GPX1(‐) and control mice at 0 mg Se/kg of feed, but were reduced (p< 0.01) by 61 and 64% in the GPX1(‐) mice at 0.5 and 3.0 mg Se/kg of feed, respectively. These results not only confirm the independent expression of GPX3, GPX4, and selenoprotein P from that of GPX1, but also show similar effects of the GPX1 knockout on Se‐dependent parameters in mice between different dietary Se concentrations, tissues, and selenoproteins.
Mitogenic effects of EGF/TGFα and immunolocalization of cognate receptors in human fetal kidneys
Authors: Chailler Pierre , Briáre Normand
Published: December 2008

The involvement of epidermal growth factor (EGF) and homologous transforming growth factor (TGF) in human kidney development was studied by analyzing their effects on the regulation of DNA synthesis in organ culture and by localizing their cognate receptors. Both peptides significantly increased 3H‐thymidine incorporation when added at 10–100 ng/ml, but not at 1–5 ng/ml. Furthermore, addition of an anti‐EGF receptor antibody not only reduced the effect of exogenous EGF (100 ng/ml) on DNA synthesis but decreased basal 3H‐thymidine incorporation. These results indicate that EGF/TGFα are both mitogenic in vitro and further suggest that human fetal kidneys release an endogenous EGF‐related substance masking the effects of low amounts of growth factors added to culture medium. Radioautographic analyses show that EGF (100 ng/ml) increased DNA synthesis in poorly‐differentiated cells of the nephrogenic zone, particularly in subcapsular mesenchyme and peritubular cells; although less responsive, epithelial cells in early nephric tubules represented another target of EGF action. The pattern of EGF/TGFα receptor expression was revealed immunohistochemically at different gestational ages and was shown to be related to the proliferation status. It was maximal in condensing nephrogenic cells, relatively high in newly‐induced epithelium and cortical branches of ureteric epithelium, low in differentiating nephronic cells and nearly absent from renal stroma and medullary collecting ducts. Together, our results indicate that the EGF/TGFα system is directly involved in the regulation of nephrogenic cell proliferation during human metanephrogenesis and it is progressively down‐regulated after conversion of mesenchyme into epithelium.
Kinetic control of internal electron transfer in cytochrome c oxidase
Authors: Brunori Maurizio , Giuffré Alessandro , D'Itri Emilio , Sarti Paolo
Published: December 2008

Two alternative hypotheses have been proposed to account for the relatively slow (ms) internal eT observed in the oxidized cyt c oxidase. The thermodynamic control hypothesis states that eT between cyt a and a3 is very fast (μs), but the apparent reduction of cyt a3 is slow because thermodynamics favors reduced cyt a. Whereas the kinetic control hypothesis states that inter‐heme eT is intrinsically slow (ms), for the oxidized binuclear center.

Monitoring by stopped flow the anaerobic reduction of the oxidized enzyme by ruthenium hexamine in the absence and presence of CO or NO, used as “trapping” ligands for cyt a32+, we found that the rate of formation of the cyt a32+—NO adduct (k′ ≈︁ 20–25 s−1) is independent of the concentration of ruthenium hexamine and NO. We conclude that in the oxidized enzyme the two hemes are not in very rapid redox equilibrium and internal eT is kinetically controlled.
The structure and function of the brown fat uncoupling protein UCP1: current status
Authors: Rial Eduardo , González‐Barroso M. Mar , Fleury Christophe , Bouillaud Frédéric
Published: December 2008

The uncoupling protein of brown adipose tissue (UCP1) is a transporter that allows the dissipation as heat of the proton gradient generated by the respiratory chain. The discovery of new UCPs in other mammalian tissues and even in plants suggests that the proton permeability of the mitochondrial inner membrane can be regulated and its control is exerted by specialised proteins. The UCP1 is regulated both at the gene and the mitochondrial level to ensure a high thermogenic capacity to the tissue. The members of the mitochondrial transporter family, which includes the UCPs, present two behaviours with carrier and channel transport modes. It has been proposed that this property reflects a functional organization in two domains: a channel and a gating domain. Mounting evidence suggest that the matrix loops contribute to the formation of the gating domain and thus they are determinants to the control of transport activity.
Protein translocation into mitochondria
Authors: Káldi Krisztina , Neupert Walter
Published: December 2008

The mitochondrial membranes contain translocation machineries (“preprotein translocases”) which facilitate transport of proteins from the cytosol into the mitochondria. The TOM complex is localized in the outer membrane. Two translocases have been characterized in the inner membrane: the Tim23‐Tim17 complex and the Tim22 complex which differ in their specificities for preproteins. The TOM and TIM complexes can act in a coordinated fashion to facilitate the insertion of preproteins into the mitochondrial membranes as well as the translocation into the internal compartments, the intermembrane space and the matrix. We discuss insights into the function of components of the translocases, illustrated by examples for mechanisms of protein sorting into the different compartments of mitochondria.
Electron microscopic tomography of rat‐liver mitochondria and their interactions with the endoplasmic reticulum
Authors: Mannella Carmen A. , Buttle Karolyn , Rath Bimal K. , Marko M.
Published: December 2008

Electron microscopic tomography can provide a complete three‐dimensional range of information about subcellular structures. Applied to mitochondria, it has shown that the conventional textbook model of this organelle is incorrect. The infoldings of the inner membrane (called cristae) are connected by narrow tubular regions to each other and to the outside, suggesting that internal diffusion of ions, metabolites and proteins may be restricted. Tomographic reconstruction of mitochondria in situ indicates these organelles may occur in clusters with stacks of endoplasmic reticulum, forming extended structures that may be involved in [Ca++] regulation.
Role of mitochondria in metabolism‐secretion coupling of insulin release in the pancreatic β‐cell
Authors: Maechler Pierre , Wollheim Claes B.
Published: December 2008

The control of insulin secretion from the pancreatic β‐cell involves a complex cascade of events in which the mitochondria play a central role. In the consensus model this role is essentially restricted to the production of ATP promoting membrane depolarisation and a rise in cytosolic [Ca2+]. Evidence for the generation of an additional mitochondrial factor implicated in metabolism‐secretion coupling is provided in this review. Although not yet identified, the formation of this putative factor requires an increase of [Ca2+] in the mitochondrial matrix together with a supply of carbons to the tricarboxylic acid (TCA) cycle. In this model, calcium activates matrix dehydrogenases, in particular those of the TCA cycle. This enables the synthesis of the mitochondrial factor from the TCA cycle intermediates. Experimental evidence gathered in permeabilised cells largely supports this model.
Apolipoprotein E (ApoE), a Bmp‐2 (bone morphogenetic protein) upregulated gene in mesenchymal progenitors (C3H10T1/2), is highly expressed in murine embryonic development
Authors: Bächner Dietmar , Schröder Dietmar , Betat Nicole , Ahrens Marion , Gross Gerhard
Published: December 2008

Apolipoprotein E (ApoE) was identified as upregulated by Bmp‐2 (bone morphogenetic protein‐2) in the murine mesenchymal progenitor cell line C3H10T1/2 by a subtractive cloning strategy. Expression of recombinant Bmps in mesenchymal C3H10T1/2 progenitors results in the differentiation into the osteogenic, the chondrogenic, and the adipogenic lineage. In addition, ApoE is also expressed in primary osteoblasts isolated from murine calvariae late in the in vitro osteoblast developmental sequence. To infer possible roles of ApoE in organogenesis and tissue differentiation, ApoE expression during mouse embryonic development was analyzed in murine midgestation and late embryonic development by in situ hybridization. ApoE is highly expressed at many sites of organ development (liver, brain, heart, eye, lung), probably in a subset of neural crest cells and ectodermal derivatives suggestive for important functions of ApoE during embryonic differentiation and organ development.
Localization and mobility of coenzyme Q in lipid bilayers and membranes
Authors: Lenaz Giorgio , Fato Romana , Di Bernardo Salvatore , Jarreta Diana , Costa Angela , Genova Maria Luisa , Castelli Giovanna Parenti
Published: December 2008

We have studied the mobility of coenzyme Q (CoQ) in lipid bilayers and mitochondrial membranes in relation to the control of electron transfer activities. A molecular dynamics computer simulation in the vacuum yielded a folded structure for CoQ10, with a length of only 21 Å. Using this information we were able to calculate diffusion coefficients in the range of 10−6 cm2/s in good agreement with those found experimentally by fluorescence quenching of pyrene derivatives. To investigate if CoQ diffusion may represent the rate‐limiting step of electron transfer, we reconstituted complexes I and III and assayed the resulting NADH‐cytochrome c reductase activity in presence of different CoQ10 levels and at different distances between complexes; the experimental turnovers were higher than the collision frequencies calculated using diffusion coefficients of 10−9 cm2/s but compatible with values found by us by fluorescence quenching. Since the experimental turnovers are independent of the distance between complexes, we conclude that CoQ diffusion is not rate‐limiting for electron transfer.
Proton translocation in the respiratory chain involving ubiquinone — a hypothetical semiquinone switch mechanism for complex I
Authors: Brandt Ulrich
Published: December 2008

The protonmotive Q‐cycle is the generally accepted reaction scheme of the cytochrome bc1 complex of the respiratory chain. It employs the redox‐dependent protonation and deprotonation of ubiquinone (coenzyme Q10) to translocate protons accross the inner mitochondrial or bacterial plasma membrane. The requirements for the operation of a similar mechanism in proton translocating NADH:ubiquinone oxidoreductase (complex I) and the specific roles of the ‘Rieske’ iron‐sulfur center in the cytochrome bc1 complex and iron‐sulfur center N‐2 in complex I are discussed.

Recent results suggest that there is only one ubiquinone‐reactive site in complex I which seems to exclude a classical Q‐cycle type mechanism. Therefore, a “semiquinone switch” mechanism is proposed involving one tightly bound and one substrate quinone. It is based on the same principles as a Q‐cycle, but is a localized rather than a ligand conduction type mechanism.
Metabolism of coenzyme Q10: Biliary and urinary excretion study in guinea pigs
Authors: Nakamura T. , Ohno T. , Hamamura K. , Sato T.
Published: December 2008

Biliary and urinary metabolites were examined after intravenous administration of 14C‐coenzyme Q10 (14C‐CoQ) to guinea pigs. Cumulative recovery of administered radioactivity for up to 8 hours by bile drainage was 4.8%. The greater part of radioactivity was detected in conjugate form. After hydrolyzing with β‐glucuronidase, aglycone fragments were subjected to methylation and reductive acetylation. The main metabolite was demonstrated to be Q acid‐I 1,4‐hydroquinone diacetate methyl ester (M‐1) on HPLC. Then, the main metabolite was assumed to be glucuronide of 2,3‐dimethoxy‐5‐methyl‐6‐(3′‐methyl‐5′‐carboxy‐2′‐pentenyl)‐1,4‐benzohydroquinone [Q acid‐I hydroquinone]. The cumulative urinary recovery of the administered radioactivity over 48 hours was 8.3%. The labeled samples were treated similarly to bile. The urinary metabolites of CoQ10 consisted of unconjugated and conjugated forms. Lyophilized urine was treated as a bile sample and analyzed. The two major metabolites were assigned to be M‐1 and Q acid‐II 1,4‐hydroquinone diacetate methyl ester (M‐2). Then, the two metabolites were assumed to be composed of Q acid‐I and 2,3‐dimethoxy‐5‐methyl‐6‐(3′‐carboxypropyl)‐1,4‐benzoquinone (Q acid‐II) in free and corresponding hydroquinone conjugate forms. To investigate the effect of exogenous labeled CoQ10 on unlabeled CoQ10 (endogenous) metabolites in urine, simultaneous quantitative determination was performed using deuterium labeled CoQ10 (CoQ10‐d5). Urine collected over a 72‐hour period after intravenous administration of CoQ10‐d5 was processed similarly to that described above and two derivatized metabolites (M‐1 and M‐2) were quantified by gas chromatography‐mass fragmentography with the multi‐ion detection method. The analytical results showed that the addition of exogenous labeled CoQ10 did not influence the metabolism (or breakdown) of unlabeled (endogenous) CoQ10.
Induction of endogenous coenzyme Q biosynthesis by administration of peroxisomal inducers
Authors: Turunen Mikael , Sindelar Pavel , Dallner Gustav
Published: December 2008

A large number of chemical compounds have been identified which cause peroxisomal proliferation and induce a number of enzymes, mainly those participating in lipid metabolism. Administration of these drugs/chemicals to rats increased coenzyme Q levels in the blood and most of the organs. Levels were raised in all cellular membranes of such organs. The extent of induction of this lipid was 8‐fold in young animals but decreased during aging and was absent at 1.5 year of age. One of the regulating factors of the mevalonate pathway is farnesol, which is produced by dephosphorylation of farnesyl‐PP and eliminated by phosphorylation including two kinases. Future research will involve a search for modified intermediary metabolites, which increase coenzyme Q synthesis and thereby efficiently elevate the level of this lipid in conditions of deficiency.
Critical aspects of the antioxidant function of coenzyme Q in biomembranes
Authors: Nohl Hans , Gille Lars , Kozlov Andrey V.
Published: December 2008

Coenzyme Q (ubiquinone, UQ) is increasingly considered as a significant natural antioxidant, which protects biomembranes in concert withα‐tocopherol. In vitro experiments demonstrated that reduced UQ (ubiquinol) can improve the chain‐breaking activities ofα‐tocopherol by recycling the antioxidant‐derived reaction product, the chromanoxyl radical, to the native antioxidant. Less attention, however, was devoted to the antioxidant‐derived reaction products of reduced UQ. Although bothα‐tocopherol and ubiquinol were found to be equally effective in scavenging chain‐propagating lipid radicals,α‐tocopherol protected lipid membranes from lipid peroxidation more efficiently than ubiquinol. The present study not only provides data which document this discrepancy but also contributes experimental data on the existence of ubiquinol derived pro‐oxidants, which give an explanation of this phenomenon.
A possible role of coenzyme Q10 in the etiology and treatment of Parkinson's disease
Authors: Shults Clifford W. , Haas Richard H. , Beal M. Flint
Published: December 2008

Parkinson's disease (PD) is a degenerative neurological disorder. Recent studies have demonstrated reduced activity of complex I of the electron transport chain in brain and platelets from patients with PD. Platelet mitochondria from parkinsonian patients were found to have lower levels of coenzyme Q10 (CoQ10) than mitochondria from age/sex‐matched controls. There was a strong correlation between the levels of CoQ10 and the activities of complexes I and II/III. Oral CoQ10 was found to protect the nigrostriatal dopaminergic system in one‐year‐old mice treated with MPTP, a toxin injurious to the nigrostriatal dopaminergic system. We further found that oral CoQ10 was well absorbed in parkinsonian patients and caused a trend toward increased complex I activity. These data suggest that CoQ10 may play a role in cellular dysfunction found in PD and may be a potential protective agent for parkinsonian patients.
Overview of the use of CoQ10 in cardiovascular disease
Authors: Langsjoen Peter H. , Langsjoen Alena M.
Published: December 2008

The clinical experience in cardiology with CoQ10 includes studies on congestive heart failure, ischemic heart disease, hypertensive heart disease, diastolic dysfunction of the left ventricle, and reperfusion injury as it relates to coronary artery bypass graft surgery. The CoQ10‐lowering effect of HMG‐CoA reductase inhibitors and the potential adverse consequences are of growing concern. Supplemental CoQ10 alters the natural history of cardiovascular illnesses and has the potential for prevention of cardiovascular disease through the inhibition of LDL cholesterol oxidation and by the maintenance of optimal cellular and mitochondrial function throughout the ravages of time and internal and external stresses. The attainment of higher blood levels of CoQ10 (>3.5 μg/ml) with the use of higher doses of CoQ10 appears to enhance both the magnitude and rate of clinical improvement. In this communication, 34 controlled trials and several open‐label and long‐term studies on the clinical effects of CoQ10 in cardiovascular diseases are reviewed.
Coenzyme Q10 treatment in serious heart failure
Authors: Munkholm H. , Hansen H. H. T. , Rasmussen K.
Published: December 2008

Several noninvasive studies have shown the effect on heart failure of treatment with coenzyme Q10. In order to confirm this by invasive methods we studied 22 patients with mean left ventricular (LV) ejection fraction 26%, mean LV internal diameter 71 mm and in NYHA class 2‐3. The patients recieved coenzyme Q10 100 mg twice daily or placebo for 12 weeks in a randomized double‐blinded placebo controlled investigation.

Before and after the treatment period, a right heart catheterisation was done including a 3 minute exercise test.

The stroke index at rest and work improved significantly, the pulmonary artery pressure at rest and work decreased (significantly at rest), and the pulmonary capillary wedge pressure at rest and work decreased (significantly at 1 min work).

These results suggest improvement in LV performance. Patients with congestive heart failure may thus benefit from adjunctive treatment with coenzyme Q10.
Coenzyme Q10improves the tolerance of the senescent myocardium to aerobic and ischemic stress: Studies in rats and in human atrial tissue
Authors: Rosenfeldt Franklin L. , Pepe Salvatore , Ou Ruchong , Mariani Justin A. , Rowland Michael A. , Nagley Phillip , Linnane Anthony W.
Published: December 2008

The inferior recovery of cardiac function after interventional cardiac procedures in elderly patients compared to younger patients suggests that the aged myocardium is more sensitive to stress. We report two studies that demonstrate an age‐related deficit in myocardial performance after aerobic and ischemic stress and the capacity of CoQ10treatment to correct age‐specific diminished recovery of function. In Study 1 the functional recovery of young (4 mo) and senescent (35 mo) isolated working rat hearts after aerobic stress produced by rapid electrical pacing was examined. After pacing, the senescent hearts, compared to young, showed reduced recovery of pre‐stress work performance. CoQ10pretreatment (daily intraperitoneal injections of 4 mg/kg CoQ10for 6 weeks) in senescent hearts improved their recovery to match that of young hearts. Study 2 tested whether the capacity of human atrial trabeculae (obtained during surgery) to recover contractile function, following ischemic stressIn vitro(60 min), is decreased with age and whether this decrease can be reversed by CoQ10. Trabeculae from older individuals (≥ 70 yr) showed reduced recovery of developed force after simulated ischemia compared to younger counterparts (<70 yr). Notably, this age‐associated effect was prevented in trabeculae pretreatedIn vitro(30 min at 24°C) with CoQ10(400 μM). We measured significantly lower CoQ10content in trabeculae from ≥ 70 yr patients.In vitropretreatment raised trabecular CoQ10content to similar levels in all groups. We conclude that, compared to younger counterparts, the senescent myocardium of rats and humans has a reduced capacity to tolerate ischemic or aerobic stress and recover pre‐stress contractile performance, however, this reduction is attenuated by CoQ10pretreatment.
Bioenergetic effect of liposomal coenzyme Q10 on myocardial ischemia reperfusion injury
Authors: Niibori Koki , Wroblewski Krzystof P. , Yokoyama Hitoshi , Crestanello Juan A. , Whitman Glenn J. R.
Published: December 2008

The antioxidant and bioenergetic effects of CoQ10 are well known but its clinical utility is limited by the requirement for enteral administration. A newly developed liposomal CoQ10 (CoQ) is water soluble and capable of intravenous administration.The purpose of this study is to determine the mechanism by which acute administration CoQ protects myocardium from reperfusion (Rp) injury. Rats were pretreated with CoQ 10 mg/kg i.v. 30 min prior to the experiment. Control rats were pretreated with liposome only. Hearts were excised and subjected to equilibration, 25 min of normothermic ischemia and 40 min of Rp on a Langendorff apparatus. At end Rp, CoQ hearts recovered 74 ± 5% of their DP vs. 50 ± 9% in control (p<0.05). Aerobic efficiency was maintained (0.66 ± 0.02 vs. control, 0.5 ± 0.04, p<0.003) and CoQ hearts lost less CK activity vs. control (p<0.02). PCr and ATP were higher than control (p<0.05, 0.02, respectively). Results show that i.v. CoQ improves recovery of function, aerobic efficiency, CK activity, and recovery of PCr and ATP after Rp. This suggests that acute administration of liposomal CoQ improves myocardial tolerance to I/R via its role as an antioxidant as well as improving oxygen utilization and high energy phosphate production.
High serum coenzyme Q10, positively correlated with age, selenium and cholesterol, in Inuit of Greenland. A pilot study
Authors: Pedersen H. S. , Mortensen S. A. , Rohde M. , Deguchi Y. , Mulvad G. , Bjerregaard P. , Hansen J. C.
Published: December 2008

Greenlanders (Eskimos) have low prevalence of ischaemic heart disease, partly explained by a lower extent of atherosclerosis and a low n‐6/n‐3 ratio of polyunsaturated fatty acids. As atherosclerosis is also a result of oxidative stress, the total antioxidative readiness could have a substantial impact. From a health survey we chose the subpopulation from the most remote area, where the traditional Greenlandic diet with high intake of sea mammals and fish predominates. The mean (SD) of S‐CoQ10 in males was 1.495 (0.529) nmol/ml and 1.421 (0.629) nmol/ml in females, significantly higher (p<0.001) compared to a Danish population. In a linear multiple regression model the S‐CoQ10 level is significantly positively associated with age and S‐selenium in males, and S‐total cholesterol in females. The high level of CoQ10 in Greenlanders probably reflects diet, since no bioaccumulation takes place, and it could probably be a substantial part of the antioxidative defense.
Olive oil supplemented with vitamin E affects mitochondrial coenzyme Q levels in liver of rats after an oxidative stress induced by adriamycin
Authors: Quiles J. L. , Ramirez‐Tortosa M. C. , Huertas J. R. , Ibañez S. , Gomez J. A. , Battino M. , Mataix J.
Published: December 2008

In this study we have evaluated the supplementation of olive oil with vitamin E on coenzyme Q concentration and lipid peroxidation in rat liver mitochondrial membranes. Four groups of rats were fed on virgin olive, olive, olive plus 200 mg/kg of vitamin E or sunflower oils as lipid dietary source. To provoke an oxidative stress rats were administered intraperitoneally 10 mg/kg/day of adriamycin the last two days of the experiment. Animals fed on olive oil plus vitamin E had significantly higher coenzyme Q and vitamin E levels but a lower mitochondrial hydroperoxide concentration than rats fed on olive oil. Retinol levels were not affected, by either different diets or adriamycin treatment. In conclusion, an increase in coenzyme Q andα‐tocopherol in these membranes can be a basis for protection against oxidation and improvement in antioxidant capacity.
Protective effect of exogenous coenzyme Q in rats subjected to partial hepatic ischemia and reperfusion
Authors: Genova Maria Luisa , Bonacorsi Elisa , D'Aurelio Marilena , Formiggini Gabriella , Nardo Bruno , Cuccomarino Salvatore , Turi Paola , Pich Milena Merlo , Lenaz Giorgio , Bovina Carla
Published: December 2008

In a surgical model of liver ischemia lipid peroxidation occurs, as shown by increase of lipid peroxidation end products, endogenous CoQ9 is oxidized and mitochondrial respiration is lowered; however, pre‐treatment of the rats by i.p. injection of CoQ10 for 14 days normalizes the above parameters, presumably by way of the observed high extent of reduction of the incorporated quinone; moreover, liver homogenates of the CoQ10‐treated rats are more resistant than those of non‐treated rats to oxidative stress induced by an azido free radical initiator. This preliminary study suggests that CoQ10 pre‐treatment can be of beneficial effect against oxidative damage during liver surgery transplantation.
Coenzyme Q10 administration increases antibody titer in hepatitis B vaccinated volunteers — A single blind placebo‐ controlled and randomized clinical study
Authors: Barbieri Bruno , Lund Bernt , Lundström Bengt , Scaglione Francesco
Published: December 2008

Persons involved in the study, 21 per treatment arm, were consuming ubiquinone (Q10), 90 mg/day, 180 mg/day or placebo, for two weeks prior to hepatitis B vaccination. After 30 days this vaccination was repeated. Q10 was given as soft gelatin capsules containing 30 mg each. The consumption was continued throughout the study conducted for 90 days. Clinical observations and laboratory tests were performed throughout the study and no adverse effects were observed in any of the groups.

Already after 30 days the two groups receiving Q10 showed a slightly higher titer of antibodies to hepatitis B surface antigen then the placebo group. This difference escalated and the immunopotentiating effect of Q10 was even more clear‐cut in the residual part of the study. In addition, a dose response did also seem to be present when comparing the 90 mg group with the 180 mg group. Statistics revealed that Q10 in the dose 180 mg/day is able to increase antibody response in vivo in humans vaccinated against hepatitis B with up to 57% (p=0.011).
Clinical implications of the correlation between coenzyme Q10 and vitamin B6 status
Authors: Willis R. , Anthony M. , Sun L. , Honse Y. , Qiao G.
Published: December 2008

The endogenous biosynthesis of the quinone nucleus of coenzyme Q10 (CoQ10) from tyrosine is dependent on adequate vitamin B6 nutriture. Lowered blood and tissue levels of CoQ10 have been observed in a number of clinical conditions. Many of these clinical conditions are most prevalent among the elderly. Kalen et al. have shown that blood levels of CoQ10 decline with age. Similarly, Kant et al. have shown that indicators of vitamin B6 status also decline with age. Blood samples were collected from 29 patients who were not currently being supplemented with either CoQ10 or vitamin B6. Mean CoQ10 concentrations was 1.1 ± 0.3 μg/ml of blood. Mean specific activities of EGOT was 0.30 ± 0.13 μmol pyruvate/hr/108 erythrocytes and the mean percent saturation of EGOT with PLP was 78.2 ± 13.9%. Means for all parameters were within normal ranges. Strong positive correlation was found between CoQ10 and the specific activity of EGOT (r =0.5787, p <0.001) and between CoQ10 and the percent saturation of EGOT with PLP (r =0.4174, p <0.024). Studies are currently in progress to determine the effect of supplementation with vitamin B6 of blood CoQ10 levels. It appears prudent to recommend that patients receiving supplemental CoQ10 be concurrently supplemented with vitamin B6 to provide for better endogenous synthesis of CoQ10 along with the exogenous CoQ10.
Manganese deficiency and toxicity: Are high or low dietary amounts of manganese cause for concern?
Authors: Finley John Weldon , Davis Cindy D.
Published: December 2008

Manganese is an essential trace element that is required for the activity of several enzymes. Manganese is also quite toxic when ingested in large amounts, such as the inhalation of Mn‐laden dust by miners. This review examines Mn intake by way of the food supply and poses the question: Is there reason to be concerned with Mn toxicity or deficiency in free‐living populations in North America? Although much remains to be learned of the functions of Mn, at present there are only a few vaguely described cases of Mn deficiency in the medical literature. Given the heterogeneity of the North American food supply, it is difficult to see the possibility of more than greatly isolated and unique instances of Mn deficiency. However, low Mn‐dependent superoxide dismutase activity may be associated with cancer susceptibility, and deserves further study. There may be reasons, however, to be concerned about Mn toxicity under some very specialized conditions. Increasing numbers of young people are adopting a vegetarian lifestyle which may greatly increase Mn intake. Iron deficiency may increase Mn absorption and further increase the body‐burden of Mn, especially in vegetarians. Mn is eliminated primarily through the bile, and hepatic dysfunction could depress Mn excretion and further contribute to the body burden. Would such a combination of events predispose substantial numbers of people to chronic Mn toxicity? At present, there is no definite proof of this occurring, but given the state of knowledge at the present time, more studies with longer time‐frames and more sensitive methods of analysis are needed.
Production and characterization of monoclonal antibodies to porcine brain pyridoxal kinase
Authors: Choi Soo Young , Kwok Francis , Bahn Jae Hoon , Jeon Seong Gyu , Ahn Yoon Kyung , Yoon Byung Hak , Lee Byung Ryong , Choi Kyung Soon , Gao G. Z.
Published: December 2008

Six monoclonal antibodies that recognize porcine brain pyridoxal kinase have been selected and designated as PK67, PK86, PK91, PK144, PK252 and PK275. A total of six monoclonal antibodies recognizing different epitopes of the enzyme were obtained, of which four inhibited the enzyme activity. When total proteins of porcine brain homogenate separated by SDS‐PAGE were subjected to monoclonal antibodies, a single reactive protein band of molecular weight 39 kDa which comigrated with purified porcine pyridoxal kinase was detected. Using the anti‐pyridoxal kinase antibodies as probes, the cross reactivities of brain pyridoxal kinase from human and other mammalian tissues and from avian sources were also investigated. Among human and all animal tissues tested, immunoreactive bands on Western blots appeared to have the same molecular mass of 39 kDa. These results indicate that mammalian brains contain only one major type of immunologically similar pyridoxal kinase, although some properties of the enzymes reported previously differed from one another.