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Title:
Cryo-electron microscopy of low density lipoprotein and reconstituted discoidal high density lipoprotein: imaging of the apolipoprotein moiety
Authors:
van Antwerpen, R.; Chen, G. C.; Pullinger, C. R.; Kane, J. P.; LaBelle, M.; Krauss, R. M.; Luna-Chavez, C.; Forte, T. M.; Gilkey, J. C.
Abstract:
Cryo-electron microscopy was used to analyze the structure of low density lipoprotein from normolipidemic subjects (N-LDL), phospholipid-depleted N-LDL (PD-LDL), small dense LDL from hypertriglyceridemic subjects (SD-LDL), and reconstituted discoidal high density lipoproteins (rHDL). In different projections of N-LDL, a high density component of the particle was visible as two parallel bands or as a single ring. Projections of PD-LDL were very similar to those of N-LDL, indicating that the contribution of phospholipid headgroups to the observed high density structure is minor. In preparations of SD-LDL, projections with two high density bands or a single high density ring were rare. Instead, triangular and diamond-shaped projections were recognized. In different projections of discoidal rHDL, a high density component was visible as a single band or as a single ring. The present results indicate that cryo-electron microscopy reveals the distribution of apolipoproteins within lipoprotein particles. Thus, apolipoprotein B-100 (apoB) in N-LDL appears to be organized as a double ring around the particle, while apoB in SD-LDL is indicated to have a different conformation. Cryo-electron micrographs of rHDL are consistent with the presence of apolipoprotein A-I on the periphery of the lipoprotein disc.
Published:
1997-04
Title:
Spectrophotometric assay for total peroxyl radical-trapping antioxidant potential in human serum
Authors:
Valkonen, M.; Kuusi, T.
Abstract:
Antioxidants prevent modification of low density lipoprotein (LDL) by free radicals and possibly also atheroma formation. The capacity of human serum to resist attacks by free radicals is measured by the total peroxyl radical-trapping potential (TRAP). Its measurement has thus far required equipment not available in many clinical laboratories such as a thermostated oxygen electrode cell or a luminometer. To develop a simpler method we used a free radical probe, dichlorofluorescin-diacetate (DCFH-DA), described before in studies of respiratory burst in inflammatory cells. Its oxidation by radicals from thermal decomposition of 2,2'-diazobis(2-amidinopropane)dihydrochloride (AAPH) converts this compound to highly fluorescent dichlorofluorescein (DCF). The DCF also has absorbance at 504 nm thus enabling the determination of TRAP either fluorometrically or spectrophotometrically. Increasing the concentration of AAPH enables the measurement of DCF formation and its inhibition by serum samples at room temperature. The intra- and interassay coefficients of variation of this assay are 3.4% and 4.6%, respectively. The mean value for serum TRAP of healthy subjects is 1155 mumol/l (n = 38). The TRAP in human serum can be increased by adding various antioxidant substances to the assay in vitro or by dietary supplementation of healthy subjects with vitamin E in vivo (P < 0.025). An increase was also found in serum vitamin E levels (P < 0.0001) and in the length of the time human LDL is able to resist oxidation (P
Published:
1997-04
Title:
Long-term vegetarian diet and bone mineral density in postmenopausal Taiwanese women
Authors:
Chiu, J. F.; Lan, S. J.; Yang, C. Y.; Wang, P. W.; Yao, W. J.; Su, L. H.; Hsieh, C. C.
Abstract:
This study examined bone density among postmenopausal Buddhist nuns and female religious followers of Buddhism in southern Taiwan and related the measurements to subjects characteristics including age, body mass, physical activity, nutrient intake, and vegetarian practice. A total of 258 postmenopausal Taiwanese vegetarian women participated in the study. Lumbar spine and femoral neck bone mineral density (BMD) were measured using dual-photon absorptimetry. BMD measurements were analyzed first as quantitative outcomes in multiple regression analyses and next as indicators of osteopenia status in logistic regression analyses. Among the independent variables examined, age inversely and body mass index positively correlated with both the spine and femoral neck BMD measurements. They were also significant predictors of the osteopenia status. Energy intake from protein was a significant correlate of lumbar spine BMD only. Other nutrients, including calcium and energy intake from nonprotein sources, did not correlate significantly with the two bone density parameters. Long-term practitioners of vegan vegetarian were found to be at a higher risk of exceeding lumbar spine fracture threshold (adjusted odds ratio = 2.48, 95% confidence interval = 1.03-5.96) and of being classified as having osteopenia of the femoral neck (3.94, 1.21-12.82). Identification of effective nutrition supplements may be necessary to improve BMD levels and to reduce the risk of osteoporosis among long-term female vegetarians.
Published:
1997-03
Title:
Time trends in serum cholesterol before cancer death
Authors:
Sharp, S. J.; Pocock, S. J.
Abstract:
Following evidence of an association between low serum cholesterol and cancer from several prospective studies, this paper concentrates on individual time trends in serial measurements of serum cholesterol before a cancer-related death. The Framingham Heart Study contains repeated measurements of cholesterol at approximately 2-year intervals in 5,209 subjects, of whom 539 died from cancer during 30 years of follow-up. We quantify (1) the change in serum total cholesterol level before cancer death, and (2) the association between fall in serum total cholesterol and odds of cancer death. The mean fall in serum total cholesterol in the 4- to 6-year period before cancer death is 8.06 (95% confidence interval = 4.58-11.54) mg per dl, with some evidence of lowered cholesterol before that period. This pattern is corroborated by evidence of a substantially increased odds of cancer death if a large fall in cholesterol occurs over any 4- to 6-year period. We suggest that these time trends can plausibly be attributed to the effects of prevalent cancer on lowering serum cholesterol; our findings add weight to the argument that the low cholesterol-cancer mortality relation does not arise because of any causal contribution of low serum total cholesterol to the risk of cancer.
Published:
1997-03
Title:
Retardation of myelination due to dietary vitamin B12 deficiency: cranial MRI findings
Authors:
Lövblad, K.; Ramelli, G.; Remonda, L.; Nirkko, A. C.; Ozdoba, C.; Schroth, G.
Abstract:
Vitamin B12 deficiency is known to be associated with signs of demyelination, usually in the spinal cord. Lack of vitamin B12 in the maternal diet during pregnancy has been shown to cause severe retardation of myelination in the nervous system. We report the case of a 14(1)/2-month-old child of strictly vegetarian parents who presented with severe psychomotor retardation. This severely hypotonic child had anemia due to insufficient maternal intake of vitamin B12 with associated megaloblastic anemia. MRI of the brain revealed severe brain atrophy with signs of retarded myelination, the frontal and temporal lobes being most severely affected. It was concluded that this myelination retardation was due to insufficient intake of vitamin B12 and vitamin B12 therapy was instituted. The patient responded well with improvement of clinical and imaging abnormalities. We stress the importance of MRI in the diagnosis and follow-up of patients with suspected diseases of myelination.
Published:
1997-02
Title:
The oxidation hypothesis of atherosclerosis: an update
Authors:
Westhuyzen, J.
Abstract:
Hypercholesterolemia is associated with an increased risk of atherosclerosis. The oxidation hypothesis suggests that oxidative modification of lipoprotein, and in particular low-density lipoprotein (LDL), increases its atherogenicity by altering receptor-mediated uptake by cells in the intima of blood vessels. Oxidized LDL is taken up by scavenger receptors on monocytes, smooth muscle cells, and macrophages in an uncontrolled process leading to accumulation of lipid and the formation of foam cells, an early feature of atherosclerotic plaque. Recent research on the oxidation of LDL lipids, the effect of antioxidants, hypertensives, and other agents, the interaction of LDL with extrinsic factors, as well as patient studies which bear on the oxidation hypothesis, are summarised in this review.
Published:
1997-02
Title:
Vascular wound healing and neointima formation induced by perivascular electric injury in mice
Authors:
Carmeliet, P.; Moons, L.; Stassen, J. M.; De Mol, M.; Bouché, A.; van den Oord, J. J.; Kockx, M.; Collen, D.
Abstract:
Vascular interventions for atherothrombotic disease frequently induce neointima formation, which can contribute to restenosis of blood vessels. As the molecular mechanisms of this process remain largely unknown, quantitative models of arterial injury in transgenic animals may be useful to study this process at the genetic level. Here, an injury model is proposed in which surgically exposed femoral arteries in mice were injured perivascularly via a single delivery of an electric current. Transmission electron microscopy, light microscopy, and immunohistochemistry revealed that electric injury destroyed all medial smooth muscle cells, denuded the injured segment of intact endothelium, and transiently induced platelet-rich mural thrombosis. A vascular wound-healing response resulted that was characterized by degradation of the mural thrombus, transient infiltration of the vessel wall by inflammatory cells, and progressive removal of the necrotic debris. Topographic analysis revealed repopulation of the media and accumulation in the neointima of smooth muscle cells originating from the uninjured borders and progressing into the necrotic center. Within 3 weeks after injury, a neointima of 0.026 +/- 0.003 mm2 (n = 7 arteries) was formed that contained a maximum of 12 +/- 1 layers of smooth muscle alpha-actin-immunoreactive cells. Evans blue staining in five electrically injured arteries revealed a denuded distance of 2.8 +/- 0.2 mm immediately after injury, which became progressively re-endothelialized from the uninjured borders to 2.2 +/- 0.08 mm (P = 0.013 vs freshly injured by analysis of variance), 0.8 +/- 0.22 mm (P < 0.001), and 0.005 +/- 0.003 mm (P
Published:
1997-02
Title:
"Where Men Will Not Work": Gender, Power, Space, and the Sexual Division of Labor in America's Meatpacking Industry, 1890-1990
Authors:
Horowitz, Roger
Abstract:
Published:
1997-01
Title:
A longitudinal study of the growth of matched pairs of vegetarian and omnivorous children, aged 7-11 years, in the north-west of England
Authors:
Nathan, I.; Hackett, A. F.; Kirby, S.
Abstract:
OBJECTIVE: To assess the ability of a meat free diet to support normal growth of children. DESIGN: A one year longitudinal observational case--comparison study of growth. SETTING: Children were recruited mainly through schools from Merseyside and all measurements were taken in their homes. SUBJECTS: Fifty 'free-living' children following meat free diets, aged 7-11 y (expected to be pre-pubertal), were compared with a control group of 50 omnivores matched for age, sex and ethnic group. INTERVENTION: None. MAIN OUTCOME MEASURES: Height, weight, upper arm skinfold thicknesses and mid-upper arm circumference measurements were taken at baseline and one year later. The increments over one year were each analysed using a multiple stepwise regression model which derived predicted increments controlled for a variety of factors other than the diet factor. RESULTS: Of all the anthropometric measurements examined only the predicted height increment of the vegetarians was slightly greater than that of the omnivores (difference in predicted height increment = 0.47 cm, P = 0.05). This difference was only apparent after allowing for father's height, maternal smoking habit and number of siblings. A tendency for the vegetarians to be leaner than the omnivores was not significant at the 5% level and both the vegetarian and omnivorous groups lay close to the 50th percentiles for both height and weight (Child Growth Foundation, 1994). CONCLUSIONS: The results suggest that these children who followed a meat free diet and conventional lifestyles grew at least as well as children who ate meat.
Published:
1997-01
Title:
Cholesterol deposition in macrophages: foam cell formation mediated by cholesterol-enriched oxidized low density lipoprotein
Authors:
Greenspan, P.; Yu, H.; Mao, F.; Gutman, R. L.
Abstract:
Oxidized low density lipoprotein (LDL) is thought to mediate the transformation of macrophages to cholesterol-rich foam cells. Yet convincing evidence for this process is lacking in vitro. We suggest that oxidized LDL-mediated foam cell formation is not seen in vitro because the cholesteryl ester content of LDL particles (oxidized in the presence of transition metals) is dramatically reduced. Thus, if oxidized LDL could be cholesterol-enriched prior to its addition to macrophages, this lipoprotein would be made more capable of inducing the cellular deposition of cholesteryl esters. When we enriched cupric sulfate-oxidized LDL with cholesterol by incubation of this lipoprotein with unesterified cholesterol/phosphatidylcholine liposomes and added it to mouse peritoneal macrophage cultures, we found that: a) the enrichment of oxidized LDL with cholesterol did not alter the extent of oxidized LDL degradation; b) the cells accumulated massive amounts of cholesteryl ester (148 microg/mg cell protein) and unesterified cholesterol (260 microg/mg cell protein) after 24 h of incubation; and c) Sephacryl S-1000 chromatography of the cholesterol-enriched oxidized LDL verified the formation of large oxidized LDL-unesterified cholesterol/phosphatidylcholine complexes. These results demonstrate that oxidized LDL, when cholesterol-enriched, can mediate the formation of macrophage foam cells in culture
Published:
1997-01
Title:
Faecal microbial flora and disease activity in rheumatoid arthritis during a vegan diet
Authors:
Peltonen, R.; Nenonen, M.; Helve, T.; Hänninen, O.; Toivanen, P.; Eerola, E.
Abstract:
To clarify the role of the faecal flora in the diet-induced decrease of rheumatoid arthritis (RA) activity, 43 RA patients were randomized into two groups: the test group to receive living food, a form of uncooked vegan diet rich in lactobacilli, and the control group to continue their ordinary omnivorous diets. Based on clinical assessments before, during and after the intervention period, a disease improvement index was constructed for each patient. According to the index, patients were assigned either to a group with a high improvement index (HI) or to a group with a low improvement index (LO). Stool samples collected from each patient before the intervention and at 1 month were analysed by direct stool sample gas-liquid chromatography of bacterial cellular fatty acids. This method has proved to be a simple and sensitive way to detect changes and differences in the faecal microbial flora between individual stool samples or groups of them. A significant, diet-induced change in the faecal flora (P = 0.001) was observed in the test group, but not in the control group. Further, in the test group, a significant (P = 0.001) difference was detected between the HI and LO categories at 1 month, but not in the pre-test samples. We conclude that a vegan diet changes the faecal microbial flora in RA patients, and changes in the faecal flora are associated with improvement in RA activity.
Published:
1997-01
Title:
37,000 Years and More in Tropical Australia: Investigating Long-Term Archaeological Trends in Cape York Peninsula
Authors:
David, B.; Lourandos, H.
Abstract:
Published:
1997
Title:
A case-control study of diet and prostate cancer
Authors:
Key, T. J.; Silcocks, P. B.; Davey, G. K.; Appleby, P. N.; Bishop, D. T.
Abstract:
We interviewed 328 men diagnosed with prostate cancer before the age of 75 years and 328 age-matched population controls. The principal hypotheses were that risk would increase with a high intake of total or saturated fat and would decrease with a high intake of carotene (beta-carotene equivalents) or lycopene. We also examined the associations of other nutrients and foods with risk. There was no evidence for an association between fat intake and risk, although the average fat intake was high and the range of fat intakes was narrow (medians of lower and upper thirds of percentage of energy from fat among controls were 34.3% and 42.9% respectively). Risk was lower in subjects with higher carotene intake: odds ratios 0.65 (95% CI 0.45-0.94) and 0.76 (0.53-1.10) in the middle and upper thirds of carotene intake respectively (P for trend = 0.150). Lycopene was not associated with risk. Among 13 other nutrients examined, the odds ratios in the top third of intake were below 0.8 for: potassium, 0.74 (0.51-1.09; P for trend = 0.054); zinc, 0.73 (0.49-1.08; P for trend = 0.126); iodine, 0.75 (0.51-1.11; P for trend = 0.077); vitamin B6 food only, 0.77 (0.53-1.12; P for trend = 0.077); and vitamin B6 including supplements, 0.70 (0.48-1.03; P for trend = 0.029). Among 18 foods examined, statistically significant associations were observed for: garlic as food, > or = 2/week vs never, 0.56 (0.33-0.93); garlic including supplements, > or = 2/week vs never, 0.60 (0.37-0.96); baked beans, > or = 2/week vs or = 5/week vs
Published:
1997
Title:
A mound complex in Louisiana at 5400-5000 years before the present
Authors:
Saunders, J.W.; Mandel, R.D.; Saucier, R.T.; Thurman Allen, E.; Hallmark, C.T.; Stringer, G.L.; Frink, D.S.; Feathers, J.K.; Williams, S.; Gremillion, K.J.; Vidrine, M.F.; Jones, Reca.
Abstract:
Published:
1997
Title:
Bone loss, traditional diet, and cold adaptation in Arctic populations
Authors:
Lazenby, Richard A.
Abstract:
North American Inuit and Inupiat ("Eskimo") populations have been described as having a lower bone mass relative to Caucasians as a consequence of their traditional high-protein "acid-ash" diet. However, this bone buffering mechanism has also been implicated as a risk factor for osteoporosis in industrialized Caucasian populations, and one recent study has found a positive association between dietary protein, and bone mass in premenopausal women. The original studies documenting the Eskimo-Caucasian difference in aging bone loss do not consider the consequences of population variation in body composition, in particular lean body mass (LBM), which correlates with bone mass. The possibility also exists that the original reference sample may be exceptional rather than normative for bone mineral density (BMD). Regression analysis was conducted on published age- and sex-specific cohort means for BMD, and bone mineral content adjusted for estimates of LBM for the original Eskimo-Caucasian comparisons, and for an additional Caucasian sample from Belgium. Significant differences were found between all groups, including Belgians, and the Wisconsin sample for BMD, supporting the notion of the latter having exceptional bone quality when measured as BMD. When adjusted for LBM, the Eskimo samples are distinct in pattern and magnitude of aging bone loss relative to Caucasians, supporting the hypothesis of real inter-population differences. However, given the current ambiguity surrounding the "protein-calcium buffering" model, an alternative explanation is offered. It is hypothesized that the accelerated bone loss among the Inuit and Inupiat reflects higher production and utilization of the thyroid hormones, T4 and T3 , as a mechanism of cold adaptation through enhanced nonshivering thermogenesis. Am. J. Hum. Biol. 9:329-341, 1997. © 1997 Wiley-Liss, Inc.
Published:
1997
Title:
Changes in cardiovascular risk factors and hormones during a comprehensive residential three month kriya yoga training and vegetarian nutrition
Authors:
Schmidt, T.; Wijga, A.; Von Zur Mühlen, A.; Brabant, G.; Wagner, T. O.
Abstract:
In participants of a comprehensive residential three month yoga and mediation training programme living on a low fat lacto-vegetarian diet changes in cardiovascular risk factors and hormones were studied. Substantial risk factor reduction was found. Body mass index, total serum and LDL cholesterol, fibrinogen, and blood pressure were significantly reduced especially in those with elevated levels. Urinary excretion of adrenaline, noradrenaline, dopamine, aldosterone, as well as serum testosterone and luteinizing hormone levels were reduced, while cortisol excretion increased significantly.
Published:
1997
Title:
Contemporary shellfish gathering strategies among the Meriam of the Torres Strait Islands, Australia: Testing predictions of a central place foraging model
Authors:
Bird, D.W.; Bliege Bird, R.L.
Abstract:
Published:
1997
Title:
Dietary strategies to improve the iron and zinc nutriture of young women following a vegetarian diet
Authors:
Gibson, R. S.; Donovan, U. M.; Heath, A. L.
Abstract:
Dietary strategies to enhance the content and bioavailability of iron and zinc in vegetarian diets were compiled. Strategies included increasing promoters and decreasing antagonists of iron and zinc absorption, adopting food preparation and processing methods which hydrolyze the phytate content of cereals and legumes, and using iron cookware. These strategies were used to devise two vegetarian menus based on food consumption patterns derived from three day weighed food records of 78 Canadian lacto-ovo-vegetarian adolescents. The iron and zinc, as well as calcium, phosphorus, thiamin, riboflavin, niacin, vitamin A, protein and energy content of the devised menus were all higher than the actual intakes and the corresponding Canadian recommended nutrient intakes. Results show the overall nutrient adequacy of the recommended vegetarian menus and indicate that young lacto-vegetarian women can potentially meet their estimated dietary requirements for absorbed iron and zinc through modest modifications to the diet. Laboratory studies designed to measure the total amount of iron and zinc absorbed from these diets by young vegetarian women are needed to verify the efficacy of the devised menus.
Published:
1997
Title:
Fat history: bodies and beauty in the modern West
Authors:
Stearns, Peter N
Abstract:
The modern struggle against fat cuts deeply and pervasively into American culture, as evidenced by the compulsion to stay thin, or at least to profess a desire to become thin. Dieting, weight consciousness, and widespread hostility to obesity form one of the fundamental themes of modern life in countries like the United States and France. Interestingly, while the French are renowned for their delight in all things gustatory, they are significantly trimmer and less diet obsessed than Americans. Fat History explores the meaning of fat and antifat in modern Western society, focusing on the uniquely moral component of dieting in America. Tracing how Western standards of beauty and physical morality have been radically transformed over the past century, Peter N. Stearns illustrates how the contemporary obsession with fat arose in tandem with the dramatic growth in consumer culture, women's increasing equality, and changes in women's sexual and maternal roles. Contrary to popular belief, fashion and nutrition have played only a secondary role in spurring the American aversion to fat, while the French distaste for obesity can be traced to different origins altogether.
Published:
1997
Title:
Identification of downstream-initiated c-Myc proteins which are dominant-negative inhibitors of transactivation by full-length c-Myc proteins
Authors:
Spotts, G.D.; Patel, S.V.; Xiao, Q.; Hann, S.R.
Abstract:
The c-myc gene has been implicated in multiple cellular processes including proliferation, differentiation, and apoptosis. In addition to the full-length c-Myc 1 and 2 proteins, we have found that human, murine, and arian cells express smaller c-Myc proteins arising from translational initiation at conserved downstream AUG codons. These c-Myc short (c-Myc S) proteins lack most of the N-terminal transactivation domain but retain the C- terminal protein dimerization and DNA binding domains. As with full-length c- Myc proteins, the c-Myc S proteins appear to be localized to the nucleus, are relatively unstable, and are phosphorylated. Significant levels of c-Myc S, often approaching the levels of full-length c-Myc, are transiently observed during the rapid growth phase of several different types of cells. Optimization of the upstream initiation codons resulted in greatly reduced synthesis of the c-Myc S proteins, suggesting that a 'leaky scanning' mechanism leads to the translation of these proteins. In some hematopoietic tumor cell lines having altered c-myc genes, the c-Myc S proteins are constitutively expressed at levels equivalent to that of full-length c-Myc. As predicted, the c-Myc S proteins are unable to activate transcription and inhibited transactivation by full-length c-Myc proteins, suggesting a dominant-negative inhibitory function. While these transcriptional inhibitors would not be expected to function as full-length c-Myc, the occurrence of tumors which express constitutive high levels of c-Myc S and their transient synthesis during rapid cell growth suggest that these proteins do not interfere with the growth-promoting functions of full-length c-Myc.
Published:
1997
Title:
Legitimizing Nutrition Education: The Impact of The Great Depression
Authors:
Babbitt, Kathleen R.
Abstract:
Published:
1997
Title:
Meat, starch and non-starch polysaccharides, are epidemiological and experimental findings consistent with acquired genetic alterations in sporadic colorectal cancer?
Authors:
Bingham, S.
Abstract:
International comparisons show strong inverse protective associations with starch, NSP (fibre, non-starch polysaccharides) and vegetable intakes, and positive associations with meat consumption in large bowel cancer. Estimates of relative risk from cohort investigations are in the same direction although generally weak, and red and processed meat, rather than white meat seem to be associated with elevated risk. A protective effect of starch and NSP probably arises from their marked effect on bacterial metabolism in the large bowel, which can be postulated to affect gene expression and DNA repair via increased butyrate production. Stool weight is also increased and pH reduced leading to alterations in secondary bile acid production, and mucosal cell proliferation. In rodent models, 'insoluble' sources of NSP are generally protective, although butyrate, resistant starch and soluble NSP may not reduce tumorigenesis. High levels of meat increase faecal ammonia and N-nitrosocompound (NOC) concentration. Some of the chromosomal mutations found in human colorectal cancer are consistent with effects of NOC and heterocyclic amines. More data are required from human experimental studies linking alterations in diet with known stages in carcinogenesis in the large bowel, and from large cohort studies which have collected biological samples in order that interaction between diet, biomarkers of diet, and different genotypes that may determine risk can be examined.
Published:
1997
Title:
Negotiating Dietary Knowledge inside and outside the Laboratories: The Cholesterol Controversy
Authors:
Garrety, Karin
Abstract:
Published:
1997
Title:
Nutrition, Activity, and Health in Children
Authors:
Dufour, Darna L.
Abstract:
This article links the nutritional statuses of children with their levels of physical activity. Both under- and overnurished children were less active than controls, while data on normally nourished children was inconclusive.
Published:
1997
Title:
Slaughterhouse: The Shocking Story of Greed, Neglect, and Inhumane Treatment Inside the U.S. Meat Industry
Authors:
Eisnitz, Gail A
Abstract:
Published:
1997
Title:
Social worlds, actor-networks and controversy: the case of cholesterol, dietary fat and heart disease.
Authors:
Garrety K
Abstract:
Knowledge which links dietary fat and cholesterol to coronary heart disease (CHD) has been controversial for more than forty years. While policies advocating fat and cholesterol restriction are now deeply ingrained in affluent western societies, the scientific 'facts' on which they are supposedly based are highly contested. Applying concepts from actor-network theory and the symbolic interactionist social worlds approach, I argue that knowledge and dietary recommendations relating to cholesterol, fat and CHD are the outcome of complex social negotiations which can only be understood in their cultural, commercial and political contexts. Policies were framed in the 1960s before 'proof' of their efficacy was available. Since then, ambiguous experimental results have been shaped to support the policies. I argue that, despite its many attractive features, actor-network theory cannot adequately deal with protracted controversies. Social worlds theory provides a much more useful framework for investigating long debates in which the 'facts' remain elusive.
Published:
1997
Title:
Substrate signaling by insulin: A ketone bodies ratio mimics insulin action in heart
Authors:
Kashiwaya, Yoshihiro; King, M. Todd; Veech, Richard L.
Abstract:
The administration of saturating doses of insulin to the glucose perfused, working rat heart acutely increased activity of the glucose transporter 4, GLUT 4, in the plasma membrane (equilibrating extracellular glucose and intracellular [glucose], activated glycogen synthase (stimulating the rate of glycogen synthesis), and increased mitochondrial acetyl CoA production by the pyruvate dehydrogenase multienzyme complex. Unexpectedly, insulin increased cardiac hydraulic work but decreased net glycolytic flux and O2consumption, improving net cardiac efficiency by 28%. These improvements in physiologic performance and metabolic efficiency resulted from reduction of the mitochondrial free [NAD+]/[NADH] and oxidation of mitochondrial [coenzyme Q]/[coenzyme QH2], increasing the energy of the proton gradient between cytosolic and mitochondrial phases and leading to a doubling of the cytosolic free [ΣATP]/[ΣADP][ΣP(i)]. The acute metabolic effects of insulin were qualitatively duplicated by addition of a ratio of 4 mM D-β-hydraxybutyrate and 1 mM acetoacetate, and the increase in the efficiency was the same as with addition of insulin. Addition of both insulin and ketones to the glucose perfusate increased the efficiency of cardiac hydraulic work by 35%. The ability of a physiologic ratio of ketone bodies to correct most of the metabolic defects of acute insulin deficiency suggests therapeutic roles for these natural substrates during periods of impaired cardiac performance and in insulin-resistant states.
Published:
1997
Title:
Systematic assessment of a maxilla of Homo from Hadar, Ethiopia
Authors:
Kimbel, W. H; Johanson, D. C; Rak, Y.
Abstract:
Published:
1997
Title:
The Fat of the Land: The Obesity Epidemic and How Overweight Americans Can Help Themselves
Authors:
Fumento, Michael
Abstract:
Published:
1997
Title:
Tropical Islands as Palaeoecological Laboratories: Gauging the Consequences of Human Arrival
Authors:
Burney, D.A.
Abstract:
Published:
1997
Title:
Unionizing the Jungles: Labor and Community in the Twentieth-Century Meatpacking Industry
Authors:
Stromquist, Shelton; Bergman, Marvin
Abstract:
Published:
1997
Title:
[Balanced vegetarian diet in combined rehabilitation of patients suffering from ischemic heart disease]
Authors:
Medkova, I. L.; Mosiakina, L. I.; Pavlova, V. E.; Zharkov, A. P.; Bugaev, V. A.; Koryshev, V. I.
Abstract:
The clinical status of 30 patients suffering from ischemic heart disease, their serum lipids and other biochemical parameters, exercise tolerance were studied. 20 patients from the group were on a specially developed antiatherosclerosis vegetarian diet VA-1; the control group comprised 10 patients who had a mixed diet A-1. It is shown that the vegetarian diet used made it possible to normalize the serum lipid spectrum, the levels of the blood pressure, to increase the tolerance to exercise, to eliminate functional disturbances of the digestive system. The investigation demonstrated the effectiveness of the vegetarian diet as a means of rehabilitation of patients suffering from ischemic heart disease.
Published:
1997
Title:
[The results of exposure to an antisclerotic vegetarian diet enriched with soy-based products on patients in the secondary prevention of ischemic heart disease]
Authors:
Medkova, I. L.; Pustynnikova, V. E.; Mosiakina, L. I.; Ieromuzo, A. A.
Abstract:
The effects of an atherogenic vegetarian diet enriched by soya-based products were investigated for the first time in this country. Clinical status and biochemical parameters of 32 patients suffering from coronary heart disease were studied. Groups 1, 2 and 3 were on the diet for 11-17, 19-22 and 30-40 days, respectively. Hyperlipidemic medicines were discontinued. The vegetarian diet resulted in normalization of the serum lipid spectrum. The most pronounced effect was achieved in group III. The developed vegetarian diet neutralized the adverse effects (an increase of cholesterol and triglycerides) of beta-blockers.
Published:
1997
Title:
Supplementation with an algae source of docosahexaenoic acid increases (n-3) fatty acid status and alters selected risk factors for heart disease in vegetarian subjects
Authors:
Conquer, J. A.; Holub, B. J.
Abstract:
The purpose of this double-blind study was to investigate the influence of dietary supplementation with an algae source of docosahexaenoic acid [DHA; 22:6(n-3)], devoid of any eicosapentaenoic acid [EPA; 20:5(n-3)], on serum/platelet DHA status, the estimated retroconversion of DHA to EPA, and risk factors for heart disease in vegetarian subjects. Healthy vegetarians (12 male, 12 female) consumed nine capsules daily of either DHA (1.62 g/d) or corn oil for 6 wk. Consumption of DHA capsules increased DHA levels in serum phospholipid by 246% (from 2.4 to 8.3 g/100 g fatty acids) and in platelet phospholipid by 225% (from 1.2 to 3.9 g/100 g fatty acids). EPA levels increased in serum phospholipid by 117% (from 0.57 to 1.3 g/100 g fatty acids) and in platelet phospholipid by 176% (0.21 to 0.58 g/100 g fatty acids) via metabolic retroconversion; the estimated extent of DHA retroconversion to EPA was 11.3 and 12.0%, based on the serum and platelet analyses, respectively. Arachidonic acid [AA; 20:4(n-6)] levels in serum and platelet phospholipids decreased moderately during the trial period (DHA group) as did both docosapentaenoic acids [22:5(n-6) and 22:5(n-3)]. Although no significant changes were found in the total and LDL-cholesterol levels with DHA supplementation, the total cholesterol:HDL-cholesterol ratio showed a moderate decrease over time as did the LDL-cholesterol:HDL-cholesterol ratio and serum triglyceride concentrations. DHA supplementation did not alter the various thrombogenic factors measured. In conclusion, DHA supplementation markedly enhanced the DHA status (of serum and platelets), provided for the formation of substantial EPA, and lowered the total and LDL-cholesterol:HDL-cholesterol ratios.
Published:
1996-12
Title:
Diet and disease--the Israeli paradox: possible dangers of a high omega-6 polyunsaturated fatty acid diet
Authors:
Yam, D.; Eliraz, A.; Berry, E. M.
Abstract:
Israel has one of the highest dietary polyunsaturated/saturated fat ratios in the world; the consumption of omega-6 polyunsaturated fatty acids (PUFA) is about 8% higher than in the USA, and 10-12% higher than in most European countries. In fact, Israeli Jews may be regarded as a population-based dietary experiment of the effect of a high omega-6 PUFA diet, a diet that until recently was widely recommended. Despite such national habits, there is paradoxically a high prevalence of cardiovascular diseases, hypertension, non-insulin-dependent diabetes mellitus and obesity-all diseases that are associated with hyperinsulinemia (HI) and insulin resistance (IR), and grouped together as the insulin resistance syndrome or syndrome X. There is also an increased cancer incidence and mortality rate, especially in women, compared with western countries. Studies suggest that high omega-6 linoleic acid consumption might aggravate HI and IR, in addition to being a substrate for lipid peroxidation and free radical formation. Thus, rather than being beneficial, high omega-6 PUFA diets may have some long-term side effects, within the cluster of hyperinsulinemia, atherosclerosis and tumorigenesis.
Published:
1996-11
Title:
Formation of oxysterols during oxidation of low density lipoprotein by peroxynitrite, myoglobin, and copper
Authors:
Patel, R. P.; Diczfalusy, U.; Dzeletovic, S.; Wilson, M. T.; Darley-Usmar, V. M.
Abstract:
Oxidation of low density lipoprotein (LDL) in the artery wall leads to the formation of cholesterol oxidation products that may result in cytotoxicity. Different mechanisms could contribute to LDL oxidation in vivo resulting in characteristic and specific modification of the cholesterol molecule. Alternatively, attack on cholesterol by chain propagating peroxyl radicals could result in the same distribution of oxidation products irrespective of the initial pro-oxidant mechanism. To distinguish between these possibilities we have monitored the formation of nine oxysterols during LDL oxidation, promoted by copper, myoglobin, peroxynitrite, or azo bis amidino propane. Regardless of the oxidant used, the pattern of oxysterol formation was essentially the same. The yields of products identified decreased in the order 7-oxocholesterol > 7 beta-hydroxycholesterol > 7 alpha-hydroxycholesterol > 5,6 beta-epoxycholesterol > 5,6 alpha-epoxycholesterol except in the case of peroxynitrite in which case a higher yield of 5, 6 beta-epoxycholesterol relative to 7-oxocholesterol was found. No formation of cholestane 3 beta, 5 alpha, 6 beta-triol, or the 24-,25-,27-hydroxycholesterols was seen. Concentration of 7-oxocholesterol levels in LDL was positively correlated with the degree of protein modification. Endogenous alpha-tocopherol in LDL or supplementation with butylated hydroxytoluene prevented oxysterol formation. Taken together these data indicate that the oxidation of cholesterol and protein in LDL occur as secondary oxidation events consequent on the attack of fatty acid peroxyl/alkoxyl radicals on the 7-position of cholesterol, and with amino acids on apoB. Furthermore, oxidant processes with atherogenic potential, such as peroxynitrite, copper, and myoglobin are capable of producing oxidized LDL containing cytotoxic mediators.
Published:
1996-11
Title:
High plasma cholesterol, but low triglycerides and plaque-free arteries, in Mexican free-tailed bats
Authors:
Widmaier, E. P.; Gornstein, E. R.; Hennessey, J. L.; Bloss, J. M.; Greenberg, J. A.; Kunz, T. H.
Abstract:
Female mammals typically become hyperphagic from mid- to late pregnancy and during lactation. Mexican free-tailed bats, Tadarida brasiliensis mexicana, double their nightly food intake from late pregnancy to peak lactation and consume an insect diet that is exceptionally high in fat. During late pregnancy and throughout lactation, fasting plasma levels of cholesterol in this insectivorous bat are high (215 +/- 8 mg/dl) and are nearly 10-fold higher than in three species of Old World frugivorous bats. Fasting triglycerides were unexpectedly low in T. brasiliensis (25 +/- 2 mg/dl), despite evidence of high fat intake during nightly feeding bouts (postprandial cholesterol and triglycerides, 268 +/- 18 and 122 +/- 20 mg/dl, respectively). High-density lipoprotein (HDL) cholesterol levels were extraordinarily high (124 +/- 5 mg/dl) and unaffected by feeding. Low-density lipoprotein cholesterol levels were correspondingly low (86 +/- 7 mg/dl). This unusual plasma lipid profile was not associated with coronary or aortic atherosclerosis, nor was there evidence of hyperglycemia or hyperinsulinemia. A high-fat diet and high levels of cholesterol in T. brasiliensis are not correlated with cardiovascular disease or (possibly) insulin resistance. Among several possible factors that might account for these observations, nightly bouts of powered flight (commuting and foraging for food) may contribute to elevated HDL cholesterol, which may protect this species from developing atherosclerosis.
Published:
1996-11
Title:
Effect of a vegan diet on biomarkers of chemoprevention in females
Authors:
Verhagen, H.; Rauma, A. L.; Törrönen, R.; de Vogel, N.; Bruijntjes-Rozier, G. C.; Drevo, M. A.; Bogaards, J. J.; Mykkänen, H.
Abstract:
1. In order to study the potential beneficial effects of a vegan diet, a cross-sectional study was performed and several biomarkers of chemoprevention were measured in a population of female 'living food' eaters ('vegans'; n = 20) vs matched omnivorous controls (n = 20). 2. White blood cells obtained from fresh blood samples were subjected to the single-cell gel-electrophoresis assay. There was no statistically significant difference between the vegans and controls in the parameters 'tail length' and 'tail moment'. However, the 'tail moment' was significantly lower in a subset of the vegans (i.e.in those who did not use any vitamin and/or mineral supplements). 3. Fresh blood samples were exposed in vitro to the mutagen mitomycin C just prior to culturing. After culturing the number of binucleated lymphocytes with micronuclei was scored. There was no difference between the controls and vegans in the incidence of baseline micronuclei, nor in the number of mitomycin C-induced micronuclei. However, a significant correlation (r = -0.64, P
Published:
1996-10
Title:
Fuel substrate turnover and oxidation and glycogen sparing with carbohydrate ingestion in non-carbohydrate-loaded cyclists
Authors:
Bosch, A. N.; Weltan, S. M.; Dennis, S. C.; Noakes, T. D.
Abstract:
This study examined the effects of ingesting 500 ml/h of either a 10% carbohydrate (CHO) drink (CI) or placebo (PI) on splanchnic glucose appearance rate (endogenous + exogenous) (Ra), plasma glucose oxidation and muscle glycogen utilisation in 17, non-carbohydrate-loaded, male, endurance-trained cyclists who rode for 180 min at 70% of maximum oxygen uptake. Mean muscle glycogen content at the start of exercise was 130 +/- 6 mmol/kg ww; (mean +/- SEM). Total CHO oxidation was similar in CI and PI subjects and declined during the trial. Ra increased significantly during the trial (P < 0.05) in both groups. Plasma glucose oxidation also increased significantly during the trial, reaching a plateau in the PI subjects, but was significantly (P < 0.05) higher in CI than PI subjects at the end of exercise [(98 +/- 14 vs. 72 +/- 10 micromol/min/kg fat-free mass) (FFM) (1.34 +/- 0.19 vs. 0.93 +/- 0. 13 g/min)]. However, mean endogenous Ra was significantly (P
Published:
1996-10
Title:
Cytochrome P4501A2: enzyme induction and genetic control in determining 4-aminobiphenyl-hemoglobin adduct levels
Authors:
Landi, M. T.; Zocchetti, C.; Bernucci, I.; Kadlubar, F. F.; Tannenbaum, S.; Skipper, P.; Bartsch, H.; Malaveille, C.; Shields, P.; Caporaso, N. E.; Vineis, P.
Abstract:
Cytochrome P4501A2 (CYP1A2) activity may be related to bladder cancer risk through metabolic activation of aromatic amines, such as 4-aminobiphenyl (ABP), to reactive intermediates that can form DNA and hemoglobin (Hb) adducts. In the context of a study on smoking and bladder cancer risk, 97 healthy male volunteers were investigated. CYP1A2-dependent N-oxidation activity was measured using a molar ratio of urinary caffeine metabolites [(paraxanthine + 1,7-dimethyluric acid)/caffeine] obtained between the fourth and fifth h after drinking a standardized cup of coffee. N-Oxidation activity was induced by blond tobacco smoke, meat consumption the dinner before the test, or more than four cups of coffee a day. The regular use of medication appeared associated with a decrease in N-oxidation levels. Age and alcohol consumption were not related with CYP1A2 activity. A polymorphic distribution of the CYP1A2 and N-acetyltransferase-2 (determined by the caffeine metabolite ratio 5-acetylamino-6-formylamino-3-methyluracil:1-methylxanthine) phenotypes was examined in relation to susceptibility to ABP-Hb adduct formation. Rapid oxidizers and subjects with the combined slow acetylator-rapid oxidizer phenotype showed the highest ABP-Hb adduct levels at a low smoking dose. Blond tobacco smokers exhibited higher adduct levels compared with black tobacco smokers, after adjustment for the quantity of cigarettes smoked. At the highest levels of smoking exposure, no major difference in ABP-Hb adduct levels was found among the different combinations of CYP1A2 and N-acetyltransferase-2 phenotypes. In a subset of only 45 available samples, no association was seen between the ABP-Hb adduct levels and the glutathione S-transferase M1 genotype.
Published:
1996-09
Title:
Pigbel-like syndrome in a vegetarian in Oxford
Authors:
Farrant, J. M.; Traill, Z.; Conlon, C.; Warren, B.; Mortensen, N.; Gleeson, F. V.; Jewell, D. P.
Abstract:
Enterocolitis necroticans or pigbel is a rare condition characteristically affecting chronically malnourished people who abruptly increase their intake of protein. The classic presentation of the disease as seen in the highlands of Papua New Guinea is that of a necrotising enterocolitis after the ritual ingestion of contaminated pork. In this context, the presentation of the same disease in a well nourished white vegetarian in Oxford was all the more intriguing.
Published:
1996-08
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