MRC Human Nutrition Research

BACKGROUND: Obesity is associated with increased mortality. Weight loss improves cardiovascular risk factors, but no prospective interventional studies have reported whether weight loss decreases overall mortality. In fact, many observational studies suggest that weight reduction is associated with increased mortality. METHODS: The prospective, controlled Swedish Obese Subjects study involved 4047 obese subjects. Of these subjects, 2010 underwent bariatric surgery (surgery group) and 2037 received conventional treatment (matched control group). We report on overall mortality during an average of 10.9 years of follow-up. At the time of the analysis (November 1, 2005), vital status was known for all but three subjects (follow-up rate, 99.9%). RESULTS: The average weight change in control subjects was less than +/-2% during the period of up to 15 years during which weights were recorded. Maximum weight losses in the surgical subgroups were observed after 1 to 2 years: gastric bypass, 32%; vertical-banded gastroplasty, 25%; and banding, 20%. After 10 years, the weight losses from baseline were stabilized at 25%, 16%, and 14%, respectively. There were 129 deaths in the control group and 101 deaths in the surgery group. The unadjusted overall hazard ratio was 0.76 in the surgery group (P=0.04), as compared with the control group, and the hazard ratio adjusted for sex, age, and risk factors was 0.71 (P=0.01). The most common causes of death were myocardial infarction (control group, 25 subjects; surgery group, 13 subjects) and cancer (control group, 47; surgery group, 29). CONCLUSIONS: Bariatric surgery for severe obesity is associated with long-term weight loss and decreased overall mortality.

For nutritional purposes, starch in foods may be classified into rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). RS may be further divided into three categories according to the reason for resistance to digestion. A method is reported for the measurement of total starch, RDS, SDS, RS and three RS fractions in starchy foods, using controlled enzymic hydrolysis with pancreatin and amyloglucosidase. The released glucose is measured by colorimetry, using a glucose oxidase kit. Values for RDS and SDS in foods obtained by the method reflect the rate of starch digestion in vivo. Values for RS are similar to the amounts of starch escaping digestion in the small intestine of ileostomates, and are a guide to the amounts of starch likely to enter the colon for fermentation. Results are given for a number of starchy foods.

Refence centile curves show the distribution of a measurement as it changes according to some covariate, often age. The LMS method summarizes the changing distribution by three curves representing the median, coefficient of variation and skewness, the latter expressed as a Box-Cox power. Using penalized likelihood the three curves can be fitted as cubic splines by non-linear regression, and the extent of smoothing required can be expressed in terms of smoothing parameters or equivalent degrees of freedom. The method is illustrated with data on triceps skinfold in Gambian girls and women, and body weight in U.S.A. girls.

BACKGROUND: Due to the high prevalence of overweight and obesity there is a need to identify cost-effective approaches for weight loss in primary care and community settings. OBJECTIVE: We evaluated the cost effectiveness of two weight loss programmes of 1-year duration, either standard care (SC) as defined by national guidelines, or a commercial provider (Weight Watchers) (CP). DESIGN: This analysis was based on a randomised controlled trial of 772 adults (87% female; age 47.4±12.9 years; body mass index 31.4±2.6 kg m(-2)) recruited by health professionals in primary care in Australia, United Kingdom and Germany. Both a health sector and societal perspective were adopted to calculate the cost per kilogram of weight loss and the ICER, expressed as the cost per quality adjusted life year (QALY). RESULTS: The cost per kilogram of weight loss was USD122, 90 and 180 for the CP in Australia, the United Kingdom and Germany, respectively. For SC the cost was USD138, 151 and 133, respectively. From a health-sector perspective, the ICER for the CP relative to SC was USD18 266, 12 100 and 40 933 for Australia, the United Kingdom and Germany, respectively. Corresponding societal ICER figures were USD31,663, 24,996 and 51,571. CONCLUSION: The CP was a cost-effective approach from a health funder and societal perspective. Despite participants in the CP group attending two to three times more meetings than the SC group, the CP was still cost effective even including these added patient travel costs. This study indicates that it is cost effective for general practitioners (GPs) to refer overweight and obese patients to a CP, which may be better value than expending public funds on GP visits to manage this problem.

We measured production of reactive oxygen species by intact mitochondria from rat skeletal muscle, heart, and liver under various experimental conditions. By using different substrates and inhibitors, we determined the sites of production (which complexes in the electron transport chain produced superoxide). By measuring hydrogen peroxide production in the absence and presence of exogenous superoxide dismutase, we established the topology of superoxide production (on which side of the mitochondrial inner membrane superoxide was produced). Mitochondria did not release measurable amounts of superoxide or hydrogen peroxide when respiring on complex I or complex II substrates. Mitochondria from skeletal muscle or heart generated significant amounts of superoxide from complex I when respiring on palmitoyl carnitine. They produced superoxide at considerable rates in the presence of various inhibitors of the electron transport chain. Complex I (and perhaps the fatty acid oxidation electron transfer flavoprotein and its oxidoreductase) released superoxide on the matrix side of the inner membrane, whereas center o of complex III released superoxide on the cytoplasmic side. These results do not support the idea that mitochondria produce considerable amounts of reactive oxygen species under physiological conditions. Our upper estimate of the proportion of electron flow giving rise to hydrogen peroxide with palmitoyl carnitine as substrate (0.15%) is more than an order of magnitude lower than commonly cited values. We observed no difference in the rate of hydrogen peroxide production between rat and pigeon heart mitochondria respiring on complex I substrates. However, when complex I was fully reduced using rotenone, rat mitochondria released significantly more hydrogen peroxide than pigeon mitochondria. This difference was solely due to an elevated concentration of complex I in rat compared with pigeon heart mitochondria. We measured production of reactive oxygen species by intact mitochondria from rat skeletal muscle, heart, and liver under various experimental conditions. By using different substrates and inhibitors, we determined the sites of production (which complexes in the electron transport chain produced superoxide). By measuring hydrogen peroxide production in the absence and presence of exogenous superoxide dismutase, we established the topology of superoxide production (on which side of the mitochondrial inner membrane superoxide was produced). Mitochondria did not release measurable amounts of superoxide or hydrogen peroxide when respiring on complex I or complex II substrates. Mitochondria from skeletal muscle or heart generated significant amounts of superoxide from complex I when respiring on palmitoyl carnitine. They produced superoxide at considerable rates in the presence of various inhibitors of the electron transport chain. Complex I (and perhaps the fatty acid oxidation electron transfer flavoprotein and its oxidoreductase) released superoxide on the matrix side of the inner membrane, whereas center o of complex III released superoxide on the cytoplasmic side. These results do not support the idea that mitochondria produce considerable amounts of reactive oxygen species under physiological conditions. Our upper estimate of the proportion of electron flow giving rise to hydrogen peroxide with palmitoyl carnitine as substrate (0.15%) is more than an order of magnitude lower than commonly cited values. We observed no difference in the rate of hydrogen peroxide production between rat and pigeon heart mitochondria respiring on complex I substrates. However, when complex I was fully reduced using rotenone, rat mitochondria released significantly more hydrogen peroxide than pigeon mitochondria. This difference was solely due to an elevated concentration of complex I in rat compared with pigeon heart mitochondria. The free radical theory of aging states that it is the mitochondrial production of reactive oxygen species (ROS), 1The abbreviations used are: ROS, reactive oxygen species; MLSP, maximum lifespan; ETF, electron transfer flavoprotein; QOR, quinone oxidoreductase; UCPs, uncoupling proteins; SOD, superoxide dismutase; BSA, bovine serum albumin. such as superoxide and hydrogen peroxide, and the resulting accumulation of damage to macromolecules that causes aging and determines maximum lifespan (MLSP) (1Harman D. J. Gerontol. 1956; 2: 298-300Google Scholar, 2Harman D. J. Am. Geriatr. Soc. 1972; 20: 145-147Google Scholar). Comparative approaches have shed considerable light on the relationship between ROS and MLSP. Notably, the rate of superoxide production by submitochondrial particles (3Sohal R.S. Svensson I. Sohal B.H. Brunk U.T. Mech. Ageing Dev. 1989; 49: 129-135Google Scholar) and the rate of H2O2 production by mitochondria (4Sohal R.S. Svensson I. Brunk U.T. Mech. Ageing Dev. 1990; 53: 209-215Google Scholar) are inversely related to MLSP in different species. A complicating factor is the association of longer MLSP with lower metabolic rates within mammals or other groups, but this complication has been resolved by the observation that birds tend to have longer MLSP than mammals with the same metabolic rate. Thus pigeons (long MLSP) have a lower rate of mitochondrial H2O2 production than rats (shorter MLSP), even though these two species have similar standard metabolic rates (5Ku H.H. Sohal R.S. Mech. Ageing Dev. 1993; 72: 67-76Google Scholar, 6Barja G. Cadenas S. Rojas C. Perez-Campo R. Lopez-Torres M. Free Radic. Res. 1994; 21: 317-327Google Scholar, 7Herrero A. Barja G. Mech. Ageing Dev. 1997; 98: 95-111Google Scholar, 8Herrero A. Barja G. J. Bioenerg. Biomembr. 1997; 29: 241-249Google Scholar). Similarly, canaries and parakeets (budgerigars) (long MLSP) have lower rates of mitochondrial H2O2 production than mice (shorter MLSP), although all three species have similar standard metabolic rates (9Herrero A. Barja G. Mech. Ageing Dev. 1998; 103: 133-146Google Scholar). Despite numerous studies reporting that mitochondria release H2O2, there is some controversy as to whether mitochondria are an important source of ROS under physiological and pathological conditions (10Forman H.J. Azzi A. FASEB J. 1997; 11: 374-375Google Scholar). In agreement with these concerns, Staniek and Nohl (12Staniek K. Nohl H. Biochim. Biophys. Acta. 2000; 1460: 268-275Google Scholar) reported that mitochondria respiring on complex I and complex II substrates do not generate H2O2 except in the presence of the complex III inhibitor antimycin A. They proposed that unspecific interactions between the commonly used methods of H2O2detection and mitochondria cause artificial rates of H2O2 production (11Staniek K. Nohl H. Biochim. Biophys. Acta. 1999; 1413: 70-80Google Scholar, 12Staniek K. Nohl H. Biochim. Biophys. Acta. 2000; 1460: 268-275Google Scholar). Two principal sites of superoxide generation have been identified in mitochondria: complex I and complex III. The relative importance of these two sites seems to vary with experimental conditions and between tissues and species (13Barja G. J. Bioenerg. Biomembr. 1999; 31: 347-366Google Scholar). There is no clear consensus in the literature about which side of the mitochondrial inner membrane superoxide is generated by complex I and complex III. In the traditional view, complex III generates superoxide on the matrix side of the mitochondrial inner membrane (14Turrens J.F. Biosci. Rep. 1997; 17: 3-8Google Scholar). The semiquinone at centero of complex III of heart mitochondria was shown to be the main producer of superoxide based on inhibitor studies (15Turrens J.F. Alexandre A. Lehninger A.L. Arch. Biochem. Biophys. 1985; 237: 408-414Google Scholar). However, the x-ray structure of complex III reveals that center o is oriented toward the intermembrane space (16Iwata S. Lee J.W. Okada K. Lee J.K. Iwata M. Rasmussen B. Link T.A. Ramaswamy S. Jap B.K. Science. 1998; 281: 64-71Google Scholar, 17Zhang Z. Huang L. Shulmeister V.M. Chi Y.I. Kim K.K. Hung L.W. Crofts A.R. Berry E.A. Kim S.H. Nature. 1998; 392: 677-684Google Scholar), suggesting that superoxide production by complex III is directed toward the cytoplasm and not toward the matrix. In support of this view, a recent study has reported that antimycin A-supplemented mitoplasts (mitochondria devoid of portions of outer membrane and cytochrome c) can release superoxide (18Han D. Williams E. Cadenas E. Biochem. J. 2001; 353: 411-416Google Scholar). In complex I, either the iron-sulfur centers (7Herrero A. Barja G. Mech. Ageing Dev. 1997; 98: 95-111Google Scholar, 19Genova M.L. Ventura B. Giuliano G. Bovina C. Formiggini G. Parenti Castelli G. Lenaz G. FEBS Lett. 2001; 505: 364-368Google Scholar) or the active site flavin (20Liu Y. Fiskum G. Schubert D. J. Neurochem. 2002; 80: 780-787Google Scholar) are thought to be mainly responsible for superoxide production. There is no x-ray crystal structure of complex I, but all of these centers are likely to face the matrix side of the membrane. 30 years ago, it was shown that the oxidation of palmitoyl carnitine by mitochondria leads to the generation of H2O2(21Boveris A. Oshino N. Chance B. Biochem. J. 1972; : 617-630Google Scholar, 22Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Google Scholar). These results received little attention and, to our knowledge, no study has examined how lipid metabolism could cause ROS generation in mammalian mitochondria. The oxidation of fatty acids involves the electron transfer flavoprotein (ETF) and the electron transfer flavoprotein quinone oxidoreductase (ETF-QOR) that could act as potential sources of ROS production. The role of lipid metabolism in the generation of ROS by mitochondria gained our attention recently when it was shown that the expression of mitochondrial uncoupling proteins (UCPs) correlates with the use of lipid as fuel substrates (23Samec S. Seydoux J. Dulloo A.G. Faseb J. 1998; 12: 715-724Google Scholar, 24Cadenas S. Buckingham J.A. S. Seydoux J. N. Dulloo A.G. FEBS Lett. 1999; Scholar) and that are by superoxide D. J. Cadenas S. J.A. J.A. A. S. Nature. 2002; Scholar). is that the elevated expression of on lipid metabolism is a of a to of ROS production the oxidation of fatty In light of the controversy the production of H2O2 by mitochondria and its to studies to the generation of ROS by mitochondria are The of the study to the production of ROS by intact mitochondria from different to the electron transport sites in ROS to the topology of ROS on which side of the inner membrane ROS are and to in the production of ROS by heart mitochondria from rat and species with similar standard metabolic rate but different MLSP. The superoxide and hydrogen peroxide from The substrates and palmitoyl inhibitors antimycin and and bovine serum from rats between and by muscle, heart, and liver mitochondria as Biochim. Biophys. Acta. 1994; Scholar), in standard and at and on Mitochondria of in rate in the presence of an was determined using the A.G. J. Scholar) with as The rate of mitochondrial production of H2O2 was determined by its with acid in the presence of G. in Scholar) using a and pigeon mitochondria at at and in standard The to the standard at the in of from at and acid and a was for mitochondrial an inhibitor of the was to of H2O2 was by and for complex in the presence of for complex II or palmitoyl carnitine in the presence of as a of palmitoyl carnitine generates amounts of which the electron transport chain at complex I, and which the and by amounts of H2O2 to in the presence of the acid and They in the absence and presence of mitochondria to whether mitochondrial with the to H2O2 Mitochondria the the of the standard in the presence of skeletal muscle, and heart mitochondria and of the of the mitochondria the of various that we to the rates of H2O2 production using skeletal muscle as an and in in the the concentration of these did not the results not of mitochondrial H2O2 production using the standard with mitochondria than using the standard the and There significant rates of in the absence of mitochondria using the standard SOD, at the rate of of cytochrome by in a with and at at in a significant to the the under all conditions and The rates of H2O2 production in by the rates measured in the absence of mitochondria mitochondria: from the rates measured in the presence of mitochondria with the results fully rates of H2O2 of H2O2 production in the presence of and and The in the absence and presence of mitochondria the of with the inhibitors of electron transport used to more the sites of ROS production G. in Scholar). complex I, at and antimycin A at centero and center of complex III which side of the mitochondrial inner membrane superoxide was we measured the rate of H2O2 production in the presence and absence of exogenous mitochondria produce on the cytoplasmic face of the inner membrane, of exogenous the rate of (and that by or and with other side to an elevated rate of H2O2 production. mitochondria generate on the matrix side of the inner membrane, of it be to the matrix H2O2 and there be no difference in the rates of H2O2 in the presence and absence of exogenous Complex I concentration was measured as by H. Scholar). using The H2O2 production rate of mitochondria from a with a substrate was compared between different experimental conditions using of and the a between rat and pigeon heart mitochondria using a The of The rate of H2O2 production by skeletal muscle or heart mitochondria with and was and was not by of A and However, the of to mitochondria respiring on and a significant rate of A This H2O2 production from the matrix side of the inner membrane the was to of exogenous A and These results that complex I in skeletal muscle and heart mitochondria can generate superoxide on the matrix side of the inner membrane when it is fully reduced and by but that the rate measured when the complex is not by is of by rat heart mitochondria. are as as palmitoyl carnitine as in is by different There was no rate of H2O2 production when skeletal muscle or heart mitochondria the presence of in the absence or presence of and There was little or no rate of H2O2 production in the presence of in the absence or presence of that complex II the can produce significant amounts of on either side of the membrane when are of antimycin A to a but measurable rate of H2O2 production that was significantly by of exogenous and These results that center o of complex III can generate on the cytoplasmic face of the inner membrane of skeletal muscle or heart mitochondria when it is reduced of the complex at center by antimycin A but that the rate measured when the complex is not by antimycin A is There was some H2O2 production in the presence of antimycin A even exogenous SOD, which that center o can produce on the matrix side of the inner membrane. However, even mitochondria produce on the cytoplasmic face of the membrane, there be a rate of H2O2 production exogenous of or and the of In other a rate of H2O2 production has a and a we can that the from the cytoplasmic face of the membrane but we be whether the the rate of from the cytoplasmic face of the membrane or H2O2 from the matrix side of the membrane. muscle or heart mitochondria respiring on palmitoyl carnitine a significant rate of H2O2 production that was not significantly by of This that oxidation of palmitoyl carnitine oxidation of and or leads to significant ROS production and that this ROS is produced on the matrix side of the inner membrane. The of to a in the rate of H2O2 production that did not and was The rates of H2O2 production in the presence of palmitoyl carnitine and similar to in the presence of and A and suggesting that complex I was the source of this ROS with either substrate when complex I was fully reduced in the presence of In the absence of rotenone, perhaps complex I is more reduced with palmitoyl carnitine as substrate to electron transport and with for than it is with and to ROS production from complex I with palmitoyl carnitine. In the presence of palmitoyl the of to an in the rate of H2O2 production that did not in skeletal muscle mitochondria and was these conditions complex I, complex and the all be H2O2 production with palmitoyl carnitine was not than with palmitoyl carnitine this was it be that and can produce some on the matrix side of the membrane. Complex II and the not be the source of such there was no in the presence of and and of antimycin A to skeletal muscle or heart mitochondria with palmitoyl carnitine the rate of H2O2 production This rate was by of skeletal muscle that of it was due to production of on the cytoplasmic face of the inner membrane. these conditions complex I, complex the and center o of complex III all be In the presence of SOD, H2O2 production with palmitoyl carnitine antimycin A to be than the of the from complex I, complex the and center o of complex III. The for this is In the rates of of liver mitochondria lower than of skeletal muscle and heart with or with palmitoyl carnitine as substrate mitochondria respiring on and produced than mitochondrial in the absence or presence of The of did not H2O2 but to the rate of H2O2 production in the presence of These results to that complex I from liver mitochondria generates ROS on the cytoplasmic face of the inner membrane as as on the matrix but of the we to be mitochondria respiring on did not generate H2O2 except perhaps for a in the presence of and antimycin A or mitochondria respiring on palmitoyl carnitine did not produce H2O2 except perhaps for a in the presence of rotenone, antimycin or However, the rates of H2O2 production it to In a of rat pigeon heart mitochondria generated measurable amounts of H2O2 when with and The of the rate of H2O2 production in species In the presence of rotenone, the H2O2 production rate of mitochondrial was with rat mitochondria than pigeon mitochondria The of complex I in the two of mitochondria was measured to whether the of rat heart mitochondria to produce ROS in the presence of was by a concentration of complex I. Complex I was significantly in rat mitochondria than in pigeon mitochondria. that the different for ROS production between rat and pigeon heart mitochondria when H2O2 production rate was of complex I. Mitochondria from rat skeletal muscle, heart, and liver respiring on substrates to complex I or complex II in the absence of other inhibitors generated little or no measurable H2O2 and The absence of significant generation of H2O2 from mitochondria respiring on complex I and complex II substrates results from Staniek and Nohl (12Staniek K. Nohl H. Biochim. Biophys. Acta. 2000; 1460: 268-275Google Scholar) a of H2O2 production from rat heart mitochondria respiring on and J. Bioenerg. Biomembr. 1997; 29: Scholar) and (20Liu Y. Fiskum G. Schubert D. J. Neurochem. 2002; 80: 780-787Google Scholar) reported rates of H2O2 production from rat heart, or liver mitochondria with or as substrates. In the absence of rotenone, considerable ROS production from complex I by electron transport Y. Fiskum G. Schubert D. J. Neurochem. 2002; 80: 780-787Google this was not in the However, other studies have reported significant rates of H2O2 production in mitochondria in G. J. Bioenerg. Biomembr. 1999; 31: 347-366Google Scholar). of these studies used in the G. Cadenas S. Rojas C. Perez-Campo R. Lopez-Torres M. Free Radic. Res. 1994; 21: 317-327Google Scholar, 7Herrero A. Barja G. Mech. Ageing Dev. 1997; 98: 95-111Google Scholar, 8Herrero A. Barja G. J. Bioenerg. Biomembr. 1997; 29: 241-249Google Scholar, G. A. J. Bioenerg. Biomembr. 1998; Scholar). We considerable rates of H2O2 generation in the presence of we did not for some of the in production of H2O2 by mitochondria respiring on complex I and II substrates between various studies be due to the presence or absence of inhibitors of electron transport or to as by and Azzi (10Forman H.J. Azzi A. FASEB J. 1997; 11: 374-375Google Scholar) and Staniek and Nohl (12Staniek K. Nohl H. Biochim. Biophys. Acta. 2000; 1460: 268-275Google Scholar). In rat skeletal muscle and heart mitochondria produced H2O2 at measurable rates when respiring on palmitoyl carnitine with no inhibitors and This H2O2 was produced on the matrix side of the membrane, it was not significantly by of exogenous The H2O2 production with palmitoyl carnitine than with complex I substrates could be complex I is more reduced with palmitoyl due to electron transport and with for of complex I to matrix ROS production with palmitoyl carnitine as it could be that and can produce on the matrix side of the membrane when palmitoyl carnitine is from in the mitochondrial matrix of the is reduced to the semiquinone and more to the fully reduced suggesting that is the electron to M. Biochem. J. Scholar). can be fully reduced by three but it two when is the electron 1985; Scholar). was proposed that the of between the and semiquinone M. Biochem. J. Scholar). These that and could act as of superoxide to presence in reduced states lipid on the production of H2O2 by mitochondria that rat liver and pigeon heart mitochondria release H2O2 when respiring on palmitoyl carnitine A. Oshino N. Chance B. Biochem. J. 1972; : 617-630Google Scholar, 22Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Google Scholar). These results gained little attention rates of H2O2 production. However, the lower rates of H2O2 production with palmitoyl carnitine in these the absence of carnitine and the use of of palmitoyl carnitine. is to that production of ROS by mitochondria lipid metabolism to an in the expression and of to the of ROS on mitochondria. In and expression is when fatty acids are (23Samec S. Seydoux J. Dulloo A.G. Faseb J. 1998; 12: 715-724Google Scholar, 24Cadenas S. Buckingham J.A. S. Seydoux J. N. Dulloo A.G. FEBS Lett. 1999; Scholar). acids and superoxide uncoupling by UCPs, and it was recently that the role of and be for ROS D. J. Cadenas S. J.A. J.A. A. S. Nature. 2002; Scholar). is commonly that of electron flow mitochondrial rise to H2O2 B. H. A. Scholar). J. Bioenerg. Biomembr. 1997; 29: Scholar) reported of free radical in the of for heart mitochondria respiring on physiological of than we our results with palmitoyl carnitine of of mitochondrial for skeletal muscle mitochondria of electron flow rise to conditions with a rate of of of mitochondrial This estimate of free radical be lower at physiological of the rate of H2O2 production by mitochondria with oxygen A. Chance B. Biochem. J. 1973; 134: 707-716Google Scholar). be even lower in more conditions of palmitoyl carnitine and lower mitochondrial membrane potential due to our upper estimate of free radical is to two of magnitude lower than the cited values. The results in this that rat heart and skeletal muscle mitochondria rates of H2O2 production than liver mitochondria either in the absence or presence of inhibitors, with the idea that tissues generate more ROS accumulation of damage S. Biochem. 1997; Scholar). A for these results is that liver mitochondria have a reduced of mitochondrial electron transport chain compared with heart and skeletal muscle Sohal R.S. Arch. Biochem. Biophys. 2000; Scholar). rat liver mitochondria have complex I and complex III than heart or skeletal muscle mitochondria Sohal R.S. Arch. Biochem. Biophys. 2000; Scholar). the potential sites of mitochondrial ROS production and the topology of ROS production from we used inhibitors of complex I and III of the electron transport chain. The inhibitors different complexes and cause to generate ROS to the of mitochondria. This to which complex has the to generate The presence and absence of the of the topology of ROS production. We that center o of complex III antimycin can generate more ROS than complex I and o of complex III generates superoxide in and on the cytoplasmic face of the mitochondrial inner membrane, whereas complex I ROS solely on the matrix side. using mitoplasts that complex III can release superoxide on the cytoplasmic face of the inner membrane (18Han D. Williams E. Cadenas E. Biochem. J. 2001; 353: 411-416Google Scholar). studies using intact mitochondria have reported in in the presence of antimycin A and (12Staniek K. Nohl H. Biochim. Biophys. Acta. 2000; 1460: 268-275Google Scholar, G. J. Bioenerg. Biomembr. 1999; 31: 347-366Google Scholar, 22Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Google Scholar, J. Bioenerg. Biomembr. 1997; 29: Sohal R.S. Arch. Biochem. Biophys. 1998; Scholar). However, of these studies examined the topology of ROS production. Mitochondria respiring on complex I substrates H2O2 production in the presence of (13Barja G. J. Bioenerg. Biomembr. 1999; 31: 347-366Google Scholar, J. Bioenerg. Biomembr. 1997; 29: Scholar). the rates in the presence of in these studies are similar or than in the presence of it is that the ROS generated in the presence of from complex I. the in the rate of by mitochondria with palmitoyl carnitine and leads to that and produce ROS on the matrix side of the inner membrane and a physiological our results H2O2 production by mitochondria respiring on complex I and II substrates in the absence of inhibitors to support for the that there is an relationship between MLSP and H2O2 production by mitochondria from various species (4Sohal R.S. Svensson I. Brunk U.T. Mech. Ageing Dev. 1990; 53: 209-215Google Scholar) or that pigeon mitochondria respiring on complex I or II substrates generate H2O2 than rat mitochondria (5Ku H.H. Sohal R.S. Mech. Ageing Dev. 1993; 72: 67-76Google Scholar, 6Barja G. Cadenas S. Rojas C. Perez-Campo R. Lopez-Torres M. Free Radic. Res. 1994; 21: 317-327Google Scholar, 7Herrero A. Barja G. Mech. Ageing Dev. 1997; 98: 95-111Google Scholar, 8Herrero A. Barja G. J. Bioenerg. Biomembr. 1997; 29: 241-249Google Scholar, G. A. J. Bioenerg. Biomembr. 1998; Scholar). we that heart mitochondria from pigeons and rats respiring on did not generate measurable amounts of In the presence of rotenone, rat mitochondria produced more H2O2 of mitochondrial than did pigeon mitochondria that the of rat mitochondria to generate ROS is This was by a of complex I in rat heart mitochondria The rates of ROS production of complex I not in rat suggesting that complex I from pigeon heart mitochondria not have a for ROS production. These that the maximum of pigeon heart mitochondria to generate ROS from complex I is than in but to support for the theory that the elevated MLSP of pigeons compared with rats is due to lower mitochondrial production of be to mitochondrial H2O2 production between of different MLSP using palmitoyl carnitine. our results not be as that mitochondria produce no ROS under physiological the substrates be from or chain fatty from lipid Our results that complexes I and III of mitochondria do produce ROS oxidation of the these ROS are by and little or no H2O2 the the other fatty acid to release of ROS, from complex I on the matrix side of the inner membrane, which can to H2O2 the However, it is important to that the complex I, complex and perhaps and do have the to generate A of to oxygen that the metabolism be to cause accumulation of resulting in We and for of complex I and for

Adenosine triphosphate (ATP) synthase contains a rotary motor involved in biological energy conversion. Its membrane-embedded F0 sector has a rotation generator fueled by the proton-motive force, which provides the energy required for the synthesis of ATP by the F1 domain. An electron density map obtained from crystals of a subcomplex of yeast mitochondrial ATP synthase shows a ring of 10 c subunits. Each c subunit forms an alpha-helical hairpin. The interhelical loops of six to seven of the c subunits are in close contact with the gamma and delta subunits of the central stalk. The extensive contact between the c ring and the stalk suggests that they may rotate as an ensemble during catalysis.

Body mass index (BMI) is the cornerstone of the current classification system for obesity and its advantages are widely exploited across disciplines ranging from international surveillance to individual patient assessment. However, like all anthropometric measurements, it is only a surrogate measure of body fatness. Obesity is defined as an excess accumulation of body fat, and it is the amount of this excess fat that correlates with ill-health. We propose therefore that much greater attention should be paid to the development of databases and standards based on the direct measurement of body fat in populations, rather than on surrogate measures. In support of this argument we illustrate a wide range of conditions in which surrogate anthropometric measures (especially BMI) provide misleading information about body fat content. These include: infancy and childhood; ageing; racial differences; athletes; military and civil forces personnel; weight loss with and without exercise; physical training; and special clinical circumstances. We argue that BMI continues to serve well for many purposes, but that the time is now right to initiate a gradual evolution beyond BMI towards standards based on actual measurements of body fat mass.

Mitochondrial oxidative damage contributes to a range of degenerative diseases. Consequently, the selective inhibition of mitochondrial oxidative damage is a promising therapeutic strategy. One way to do this is to invent antioxidants that are selectively accumulated into mitochondria within patients. Such mitochondria-targeted antioxidants have been developed by conjugating the lipophilic triphenylphosphonium cation to an antioxidant moiety, such as ubiquinol or alpha-tocopherol. These compounds pass easily through all biological membranes, including the blood-brain barrier, and into muscle cells and thus reach those tissues most affected by mitochondrial oxidative damage. Furthermore, because of their positive charge they are accumulated several-hundredfold within mitochondria driven by the membrane potential, enhancing the protection of mitochondria from oxidative damage. These compounds protect mitochondria from damage following oral delivery and may therefore form the basis for mitochondria-protective therapies. Here we review the background and work to date on this class of mitochondria-targeted antioxidants.

Association tests of multilocus haplotypes are of interest both in linkage disequilibrium mapping and in candidate gene studies. For case-parent trios, I discuss the extension of existing multilocus methods to include ambiguous haplotypes in tests of models which distinguish between the cis and trans phase. A likelihood-ratio test is proposed, using the expectation-maximization (E-M) algorithm to account for haplotype ambiguities. Assumptions about the population structure are required, but realistic situations, including population stratification, which violate the assumptions lead to conservative tests. I describe a permutation procedure for the null hypothesis of interest, which controls for violation of the assumptions. For general pedigrees, I describe extensions of the pedigree disequilibrium test to include uncertain haplotypes. The summary statistics are replaced by their expected values over prior distributions of haplotype frequencies. If prior distributions are not available, a valid test is possible by using the E-M algorithm to estimate the null distribution of haplotype frequencies. Similar methods are available for quantitative traits. Exact permutation tests are difficult to construct in small samples, but an approximate procedure is appropriate in large samples, and can be used to account for dependencies between tests of multiple haplotypes and loci.

To update the British growth reference, anthropometric data for weight, height, body mass index (weight/height2) and head circumference from 17 distinct surveys representative of England, Scotland and Wales (37,700 children, age range 23 weeks gestation to 23 years) were analysed by maximum penalized likelihood using the LMS method. This estimates the measurement centiles in terms of three age-sex-specific cubic spline curves: the L curve (Box-Cox power to remove skewness), M curve (median) and S curve (coefficient of variation). A two-stage fitting procedure was developed to model the age trends in median weight and height, and simulation was used to estimate confidence intervals for the fitted centiles. The reference converts measurements to standard deviation scores (SDS) that are very close to Normally distributed - the means, medians and skewness for the four measurements are effectively zero overall, with standard deviations very close to one and only slight evidence of positive kurtosis beyond+/-2 SDS. The ability to express anthropometry as SDS greatly simplifies growth assessment.

The wide range of phenotypic abnormalities seen in the leptin-deficient ob/ob mouse and their reversibility by leptin administration provide compelling evidence for the existence of multiple physiological functions of this hormone in rodents.In contrast, information regarding the roles of this hormone in humans is limited.Three morbidly obese children, who were congenitally deficient in leptin, were treated with daily subcutaneous injections of recombinant human leptin for up to 4 years with sustained, beneficial effects on appetite, fat mass, hyperinsulinemia, and hyperlipidemia.Leptin therapy resulted in a rapid and sustained increase in plasma thyroid hormone levels and, through its age-dependent effects on gonadotropin secretion, facilitated appropriately timed pubertal development.Leptin deficiency was associated with reduced numbers of circulating CD4 + T cells and impaired T cell proliferation and cytokine release, all of which were reversed by recombinant human leptin administration.The subcutaneous administration of recombinant human leptin has major and sustained beneficial effects on the multiple phenotypic abnormalities associated with congenital human leptin deficiency.

This report describes a set of scientific procedures used to assess the impact of foods and food ingredients on the expression of appetite (psychological and behavioural). An overarching priority has been to enable potential evaluators of health claims about foods to identify justified claims and to exclude claims that are not supported by scientific evidence for the effect cited. This priority follows precisely from the principles set down in the PASSCLAIM report. The report allows the evaluation of the strength of health claims, about the effects of foods on appetite, which can be sustained on the basis of the commonly used scientific designs and experimental procedures. The report includes different designs for assessing effects on satiation as opposed to satiety, detailed coverage of the extent to which a change in hunger can stand alone as a measure of appetite control and an extensive discussion of the statistical procedures appropriate for handling data in this field of research. Because research in this area is continually evolving, new improved methodologies may emerge over time and will need to be incorporated into the framework. One main objective of the report has been to produce guidance on good practice in carrying out appetite research, and not to set down a series of commandments that must be followed.

BACKGROUND: Randomized trials assessing BCG vaccine protection against tuberculosis have widely varying results, for reasons that are not well understood. METHODS: We examined associations of trial setting and design with BCG efficacy against pulmonary and miliary or meningeal tuberculosis by conducting a systematic review, meta-analyses, and meta-regression. RESULTS: We identified 18 trials reporting pulmonary tuberculosis and 6 reporting miliary or meningeal tuberculosis. Univariable meta-regression indicated efficacy against pulmonary tuberculosis varied according to 3 characteristics. Protection appeared greatest in children stringently tuberculin tested, to try to exclude prior infection with Mycobacterium tuberculosis or sensitization to environmental mycobacteria (rate ratio [RR], 0.26; 95% confidence interval [CI], .18-.37), or infants (RR, 0.41; 95% CI, .29-.58). Protection was weaker in children not stringently tested (RR, 0.59; 95% CI, .35-1.01) and older individuals stringently or not stringently tested (RR, 0.88; 95% CI, .59-1.31 and RR, 0.81; 95% CI, .55-1.22, respectively). Protection was higher in trials further from the equator where environmental mycobacteria are less and with lower risk of diagnostic detection bias. These associations were attenuated in a multivariable model, but each had an independent effect. There was no evidence that efficacy was associated with BCG strain. Protection against meningeal and miliary tuberculosis was also high in infants (RR, 0.1; 95% CI, .01-.77) and children stringently tuberculin tested (RR, 0.08; 95% CI, .03-.25). CONCLUSIONS: Absence of prior M. tuberculosis infection or sensitization with environmental mycobacteria is associated with higher efficacy of BCG against pulmonary tuberculosis and possibly against miliary and meningeal tuberculosis. Evaluations of new tuberculosis vaccines should account for the possibility that prior infection may mask or block their effects.

Whether early diet influences long-term health or achievement is a key question in nutrition. Such long-term consequences would invoke the concept of 'programming'--a more general process whereby a stimulus or insult at a critical period of development has lasting or lifelong significance. Data from small mammals and primates show that early nutrition may have potentially important long-term effects, for example on blood lipids, plasma insulin, obesity, atherosclerosis, behaviour and learning. Corresponding studies in man have been largely retrospective and difficult to interpret. The preterm infant is however an important model for human research because formal random assignment to early diet is practical. A large prospective randomized multicentre study has been undertaken on 926 preterm infants to test the hypothesis that early diet influences long-term outcome. Diets included human milk, standard formula and nutrient-enriched preterm formula. The diet consumed for on average the first month post partum had a major impact on subsequent developmental attainment, growth and allergic status in early childhood. That such a brief period of dietary manipulation has lasting significance implies that the neonatal period is critical for nutrition after preterm birth. These data may have broader implications for human nutrition.

BACKGROUND: Studies of weight-control diets that are high in protein or low in glycemic index have reached varied conclusions, probably owing to the fact that the studies had insufficient power. METHODS: We enrolled overweight adults from eight European countries who had lost at least 8% of their initial body weight with a 3.3-MJ (800-kcal) low-calorie diet. Participants were randomly assigned, in a two-by-two factorial design, to one of five ad libitum diets to prevent weight regain over a 26-week period: a low-protein and low-glycemic-index diet, a low-protein and high-glycemic-index diet, a high-protein and low-glycemic-index diet, a high-protein and high-glycemic-index diet, or a control diet. RESULTS: A total of 1209 adults were screened (mean age, 41 years; body-mass index [the weight in kilograms divided by the square of the height in meters], 34), of whom 938 entered the low-calorie-diet phase of the study. A total of 773 participants who completed that phase were randomly assigned to one of the five maintenance diets; 548 completed the intervention (71%). Fewer participants in the high-protein and the low-glycemic-index groups than in the low-protein-high-glycemic-index group dropped out of the study (26.4% and 25.6%, respectively, vs. 37.4%; P=0.02 and P=0.01 for the respective comparisons). The mean initial weight loss with the low-calorie diet was 11.0 kg. In the analysis of participants who completed the study, only the low-protein-high-glycemic-index diet was associated with subsequent significant weight regain (1.67 kg; 95% confidence interval [CI], 0.48 to 2.87). In an intention-to-treat analysis, the weight regain was 0.93 kg less (95% CI, 0.31 to 1.55) in the groups assigned to a high-protein diet than in those assigned to a low-protein diet (P=0.003) and 0.95 kg less (95% CI, 0.33 to 1.57) in the groups assigned to a low-glycemic-index diet than in those assigned to a high-glycemic-index diet (P=0.003). The analysis involving participants who completed the intervention produced similar results. The groups did not differ significantly with respect to diet-related adverse events. CONCLUSIONS: In this large European study, a modest increase in protein content and a modest reduction in the glycemic index led to an improvement in study completion and maintenance of weight loss. (Funded by the European Commission; ClinicalTrials.gov number, NCT00390637.).

Over 20 severely obese subjects in 11 independent kindreds have been reported to have pathogenic heterozygous mutations in the gene encoding the melanocortin 4 receptor (MC4R), making this the most common known monogenic cause of human obesity. To date, the detailed clinical phenotype of this dominantly inherited disorder has not been defined, and no homozygous subjects have been described. We determined the nucleotide sequence of the entire coding region of the MC4R gene in 243 subjects with severe, early-onset obesity. A novel two-base pair GT insertion in codon 279 was found in two unrelated subjects, and four novel missense mutations, N62S, R165Q, V253I, C271Y, and one mutation (T112M) reported previously were found in five subjects. N62S was found in homozygous form in five children with severe obesity from a consanguineous pedigree. All four heterozygous carriers were nonobese. Several features of the phenotype, e.g. hyperphagia, tendency toward tall stature, hyperinsulinemia, and preserved reproductive function, closely resemble those reported previously in Mc4r knock-out mice. In addition, a marked increase in bone mineral density was seen in all affected subjects. In transient transfection assays, the N62S mutant receptor showed a responsiveness to alphaMSH that was intermediate between the wild-type receptor and mutant receptors carrying nonsense and missense mutations associated with dominantly inherited obesity. Thus MC4R mutations result in a syndrome of hyperphagic obesity in humans that can present with either dominant or recessive patterns of inheritance.

BACKGROUND: The tolerability of oral iron supplementation for the treatment of iron deficiency anemia is disputed. OBJECTIVE: Our aim was to quantify the odds of GI side-effects in adults related to current gold standard oral iron therapy, namely ferrous sulfate. METHODS: Systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating GI side-effects that included ferrous sulfate and a comparator that was either placebo or intravenous (i.v.) iron. Random effects meta-analysis modelling was undertaken and study heterogeneity was summarised using I2 statistics. RESULTS: Forty three trials comprising 6831 adult participants were included. Twenty trials (n = 3168) had a placebo arm and twenty three trials (n = 3663) had an active comparator arm of i.v. iron. Ferrous sulfate supplementation significantly increased risk of GI side-effects versus placebo with an odds ratio (OR) of 2.32 [95% CI 1.74-3.08, p<0.0001, I2 = 53.6%] and versus i.v. iron with an OR of 3.05 [95% CI 2.07-4.48, p<0.0001, I2 = 41.6%]. Subgroup analysis in IBD patients showed a similar effect versus i.v. iron (OR = 3.14, 95% CI 1.34-7.36, p = 0.008, I2 = 0%). Likewise, subgroup analysis of pooled data from 7 RCTs in pregnant women (n = 1028) showed a statistically significant increased risk of GI side-effects for ferrous sulfate although there was marked heterogeneity in the data (OR = 3.33, 95% CI 1.19-9.28, p = 0.02, I2 = 66.1%). Meta-regression did not provide significant evidence of an association between the study OR and the iron dose. CONCLUSIONS: Our meta-analysis confirms that ferrous sulfate is associated with a significant increase in gastrointestinal-specific side-effects but does not find a relationship with dose.

Two theories of how energy metabolism should be associated with longevity, both mediated via free-radical production, make completely contrary predictions. The 'rate of living-free-radical theory' (Pearl, 1928; Harman, 1956; Sohal, 2002) suggests a negative association, the 'uncoupling to survive' hypothesis (Brand, 2000) suggests the correlation should be positive. Existing empirical data on this issue is contradictory and extremely confused (Rubner, 1908; Yan & Sohal, 2000; Ragland & Sohal, 1975; Daan et al., 1996; Wolf & Schmid-Hempel, 1989]. We sought associations between longevity and individual variations in energy metabolism in a cohort of outbred mice. We found a positive association between metabolic intensity (kJ daily food assimilation expressed as g/body mass) and lifespan, but no relationships of lifespan to body mass, fat mass or lean body mass. Mice in the upper quartile of metabolic intensities had greater resting oxygen consumption by 17% and lived 36% longer than mice in the lowest intensity quartile. Mitochondria isolated from the skeletal muscle of mice in the upper quartile had higher proton conductance than mitochondria from mice from the lowest quartile. The higher conductance was caused by higher levels of endogenous activators of proton leak through the adenine nucleotide translocase and uncoupling protein-3. Individuals with high metabolism were therefore more uncoupled, had greater resting and total daily energy expenditures and survived longest - supporting the 'uncoupling to survive' hypothesis.

Respiratory complex I plays a central role in cellular energy production in bacteria and mitochondria. Its dysfunction is implicated in many human neurodegenerative diseases, as well as in aging. The crystal structure of the hydrophilic domain (peripheral arm) of complex I from Thermus thermophilus has been solved at 3.3 angstrom resolution. This subcomplex consists of eight subunits and contains all the redox centers of the enzyme, including nine iron-sulfur clusters. The primary electron acceptor, flavin-mononucleotide, is within electron transfer distance of cluster N3, leading to the main redox pathway, and of the distal cluster N1a, a possible antioxidant. The structure reveals new aspects of the mechanism and evolution of the enzyme. The terminal cluster N2 is coordinated, uniquely, by two consecutive cysteines. The novel subunit Nqo15 has a similar fold to the mitochondrial iron chaperone frataxin, and it may be involved in iron-sulfur cluster regeneration in the complex.

Fast foods are frequently linked to the epidemic of obesity, but there has been very little scientific appraisal of a possible causal role. Here we review a series of studies demonstrating that the energy density of foods is a key determinant of energy intake. These studies show that humans have a weak innate ability to recognise foods with a high energy density and to appropriately down-regulate the bulk of food eaten in order to maintain energy balance. This induces so called 'passive over-consumption'. Composition data from leading fast food company websites are then used to illustrate that most fast foods have an extremely high energy density. At some typical outlets the average energy density of the entire menus is approximately 1100 kJ 100 g(-1). This is 65% higher than the average British diet (approximately 670 kJ 100 g(-1)) and more than twice the energy density of recommended healthy diets (approximately 525 kJ 100 g(-1)). It is 145% higher than traditional African diets (approximately 450 kJ 100 g(-1)) that probably represent the levels against which human weight regulatory mechanisms have evolved. We conclude that the high energy densities of many fast foods challenge human appetite control systems with conditions for which they were never designed. Among regular consumers they are likely to result in the accidental consumption of excess energy and hence to promote weight gain and obesity.