The first international mini-symposium on methionine restriction and lifespan.

It has been 20 years since the Orentreich Foundation for the Advancement of Science, under the leadership Dr. Norman Orentreich, first reported that low methionine (Met) ingestion by rats extends lifespan (Orentreich et al., 1993). Since then, several studies have replicated the effects of dietary methionine restricted (MR) in delaying age-related diseases (Richie et al., 1994; Miller et al., 2005; Ables et al., 2012; Sanchez-Roman and Barja, 2013). We report the abstracts from the First International Mini-Symposium on Methionine Restriction and Lifespan held in Tarrytown, NY, September 2013. The goals were (1) to gather researchers with an interest in MR and lifespan, (2) to exchange knowledge, (3) to generate ideas for future investigations, and (4) to strengthen relationships within this community. The presentations highlighted the importance of research on cysteine, growth hormone (GH), and ATF4 in the paradigm of aging. In addition, the effects of dietary restriction or MR in the kidneys, liver, bones, and the adipose tissue were discussed. The symposium also emphasized the value of other species, e.g., the naked mole rat, Brandt's bat, and Drosophila, in aging research. Overall, the symposium consolidated scientists with similar research interests and provided opportunities to conduct future collaborative studies (Figure 3).

Methionine restriction prevents the progression of hepatic steatosis in leptin-deficient obese mice.

OBJECTIVE: This study investigated the effects of dietary methionine restriction (MR) on the progression of established hepatic steatosis in the leptin-deficient ob/ob mouse. MATERIAL/METHODS: Ten-week-old ob/ob mice were fed diets containing 0.86% (control-fed; CF) or 0.12% methionine (MR) for 14 weeks. At 14 weeks, liver and fat were excised and blood was collected for analysis. In another study, blood was collected to determine in vivo triglyceride (TG) and very-low-density lipoprotein (VLDL) secretion rates. Liver histology was conducted to determine the severity of steatosis. Hepatic TG, free fatty acid levels, and fatty acid oxidation (FAO) were also measured. Gene expression was analyzed by quantitative PCR. RESULTS: MR reversed the severity of steatosis in the ob/ob mouse. This was accompanied by reduced body weight despite similar weight-specific food intake. Compared with the CF group, hepatic TG levels were significantly reduced in response to MR, but adipose tissue weight was not decreased. MR reduced insulin and HOMA ratios but increased total and high-molecular-weight adiponectin levels. Scd1 gene expression was significantly downregulated, while Acadvl, Hadha, and Hadhb were upregulated in MR, corresponding with increased ß-hydroxybutyrate levels and a trend toward increased FAO. The VLDL secretion rate was also significantly increased in the MR mice, as were the mRNA levels of ApoB and Mttp. The expression of inflammatory markers, such as Tnf-α and Ccr2, was also downregulated by MR. CONCLUSIONS: Our data indicate that MR reverses steatosis in the ob/ob mouse liver by promoting FAO, increasing the export of lipids, and reducing obesity-related inflammatory responses.

Metabolic adaptations to methionine restriction that benefit health and lifespan in rodents.

Restriction of dietary methionine by 80% slows the progression of aged-related diseases and prolongs lifespan in rodents. A salient feature of the methionine restriction phenotype is the significant reduction of adipose tissue mass, which is associated with improvement of insulin sensitivity. These beneficial effects of MR involve a host of metabolic adaptations leading to increased mitochondrial biogenesis and function, elevated energy expenditure, changes of lipid and carbohydrate homeostasis, and decreased oxidative damage and inflammation. This review summarizes observations from MR studies and provides insight about potential mediators of tissue-specific responses associated with MR's favorable metabolic effects that contribute to health and lifespan extension.

Effect of taurine and N-acetylcysteine on methionine restriction-mediated adiposity resistance.

OBJECTIVES: Methionine-restricted (MR) rats, which are lean and insulin sensitive, have low serum total cysteine (tCys) and taurine and decreased hepatic expression and activity indices of stearoyl-coenzyme A desaturase-1 (SCD1). These effects are partly or completely reversed by cysteine supplementation. We investigated whether reversal of MR phenotypes can be achieved by other sulfur compounds, namely taurine or N-acetylcysteine (NAC). METHODS: MR and control-fed (CF) rats were supplemented with taurine (0.5%) or NAC (0.5%) for 12weeks. Adiposity, serum sulfur amino acids (SAA), Scd1 gene expression in liver and white adipose tissue, and SCD1 activity indices (calculated from serum fatty acid profile) were monitored. RESULTS: Taurine supplementation of MR rats did not restore weight gain or hepatic Scd1 expression or indices to CF levels, but further decreased adiposity. Taurine supplementation of CF rats did not affect adiposity, but lowered triglyceridemia. NAC supplementation in MR rats raised tCys and partly or completely reversed MR effects on weight, fat %, Scd1 expression in liver and white adipose tissue, and estimated SCD1 activity. In CF rats, NAC decreased body fat % and lowered SCD1-18 activity index (P<0.001). Serum triglycerides and leptin were over 40% lower in CF+NAC relative to CF rats (P≤0.003 for both). In all groups, change in tCys correlated with change in SCD1-16 index (partial r=0.60, P<0.001) independent of other SAA. CONCLUSION: The results rule out taurine as a mediator of increased adiposity produced by cysteine in MR, and show that NAC, similar to L-cysteine, blocks anti-obesity effects of MR. Our data show that dietary SAA can influence adiposity in part through mechanisms that converge on SCD1 function. This may have implications for understanding and preventing human obesity.

Methionine-restricted C57BL/6J mice are resistant to diet-induced obesity and insulin resistance but have low bone density.

Dietary methionine restriction (MR) extends lifespan, an effect associated with reduction of body weight gain, and improvement of insulin sensitivity in mice and rats as a result of metabolic adaptations in liver, adipose tissue and skeletal muscle. To test whether MR confers resistance to adiposity and insulin resistance, C57BL/6J mice were fed a high fat diet (HFD) containing either 0.86% methionine (control fed; CF) or 0.12% methionine (methionine-restricted; MR). MR mice on HFD had lower body weight gain despite increased food intake and absorption efficiency compared to their CF counterparts. MR mice on HFD were more glucose tolerant and insulin sensitive with reduced accumulation of hepatic triglycerides. In plasma, MR mice on HFD had higher levels of adiponectin and FGF21 while leptin and IGF-1 levels were reduced. Hepatic gene expression showed the downregulation of Scd1 while Pparg, Atgl, Cd36, Jak2 and Fgf21 were upregulated in MR mice on HFD. Restriction of growth rate in MR mice on HFD was also associated with lower bone mass and increased plasma levels of the collagen degradation marker C-terminal telopeptide of type 1 collagen (CTX-1). It is concluded that MR mice on HFD are metabolically healthy compared to CF mice on HFD but have decreased bone mass. These effects could be associated with the observed increase in FGF21 levels.

Genomic and metabolic responses to methionine-restricted and methionine-restricted, cysteine-supplemented diets in Fischer 344 rat inguinal adipose tissue, liver and quadriceps muscle.

BACKGROUND/AIMS: Methionine restriction (MR) is a dietary intervention that increases lifespan, reduces adiposity and improves insulin sensitivity. These effects are reversed by supplementation of the MR diet with cysteine (MRC). Genomic and metabolomic studies were conducted to identify potential mechanisms by which MR induces favorable metabolic effects, and that are reversed by cysteine supplementation. METHODS: Gene expression was examined by microarray analysis and TaqMan quantitative PCR. Levels of selected proteins were measured by Western blot and metabolic intermediates were analyzed by mass spectrometry. RESULTS: MR increased lipid metabolism in inguinal adipose tissue and quadriceps muscle while it decreased lipid synthesis in liver. In inguinal adipose tissue, MR not only caused the transcriptional upregulation of genes associated with fatty acid synthesis but also of Lpin1, Pc, Pck1 and Pdk1, genes that are associated with glyceroneogenesis. MR also upregulated lipolysis-associated genes in inguinal fat and led to increased oxidation in this tissue, as suggested by higher levels of methionine sulfoxide and 13-HODE + 9-HODE compared to control-fed (CF) rats. Moreover, MR caused a trend toward the downregulation of inflammation-associated genes in inguinal adipose tissue. MRC reversed most gene and metabolite changes induced by MR in inguinal adipose tissue, but drove the expression of Elovl6, Lpin1, Pc, and Pdk1 below CF levels. In liver, MR decreased levels of a number of long-chain fatty acids, glycerol and glycerol-3-phosphate corresponding with the gene expression data. Although MR increased the expression of genes associated with carbohydrate metabolism, levels of glycolytic intermediates were below CF levels. MR, however, stimulated gluconeogenesis and ketogenesis in liver tissue. As previously reported, sulfur amino acids derived from methionine were decreased in liver by MR, but homocysteine levels were elevated. Increased liver homocysteine levels by MR were associated with decreased cystathionine ß-synthase (CBS) protein levels and lowered vitamin B6 and 5-methyltetrahydrofolate (5MeTHF) content. Finally, MR upregulated fibroblast growth factor 21 (FGF21) gene and protein levels in both liver and adipose tissues. MRC reversed some of MR's effects in liver and upregulated the transcription of genes associated with inflammation and carcinogenesis such as Cxcl16, Cdh17, Mmp12, Mybl1, and Cav1 among others. In quadriceps muscle, MR upregulated lipid metabolism-associated genes and increased 3-hydroxybutyrate levels suggesting increased fatty acid oxidation as well as stimulation of gluconeogenesis and glycogenolysis in this tissue. CONCLUSION: Increased lipid metabolism in inguinal adipose tissue and quadriceps muscle, decreased triglyceride synthesis in liver and the downregulation of inflammation-associated genes are among the factors that could favor the lean phenotype and increased insulin sensitivity observed in MR rats.

Circulating angiopoietins-1 and -2, angiopoietin receptor Tie-2 and vascular endothelial growth factor-A as biomarkers of acute myocardial infarction: a prospective nested case-control study.

BACKGROUND: Angiogenesis is up-regulated in myocardial ischemia. However, limited data exist assessing the value of circulating angiogenic biomarkers in predicting future incidence of acute myocardial infarction (AMI). Our aim was to examine the association between circulating levels of markers of angiogenesis with risk of incident acute myocardial infarction (AMI) in men and women. METHODS: We performed a case-control study (nested within a large cohort of persons receiving care within Kaiser Permanente of Northern California) including 695 AMI cases and 690 controls individually matched on age, gender and race/ethnicity. RESULTS: Median [inter-quartile range] serum concentrations of vascular endothelial growth factor-A (VEGF-A; 260 [252] vs. 235 [224] pg/mL; p = 0.01) and angiopoietin-2 (Ang-2; 1.18 [0.66] vs. 1.05 [0.58] ng/mL; p < 0.0001) were significantly higher in AMI cases than in controls. By contrast, endothelium-specific receptor tyrosine kinase (Tie-2; 14.2 [3.7] vs. 14.0 [3.1] ng/mL; p = 0.07) and angiopoietin-1 levels (Ang-1; 33.1 [13.6] vs. 32.5 [12.7] ng/mL; p = 0.52) did not differ significantly by case-control status. After adjustment for educational attainment, hypertension, diabetes, smoking, alcohol consumption, body mass index, LDL-C, HDL-C, triglycerides and C-reactive protein, each increment of 1 unit of Ang-2 as a Z score was associated with 1.17-fold (95 percent confidence interval, 1.02 to 1.35) increased odds of AMI, and the upper quartile of Ang-2, relative to the lowest quartile, was associated with 1.63-fold (95 percent confidence interval, 1.09 to 2.45) increased odds of AMI. CONCLUSIONS: Our data support a role of Ang-2 as a biomarker of incident AMI independent of traditional risk factors.

Dietary methionine restriction increases fat oxidation in obese adults with metabolic syndrome.

OBJECTIVE: In preclinical reports, restriction of dietary methionine intake was shown to enhance metabolic flexibility, improve lipid profiles, and reduce fat deposition. The present report is the outcome of a "proof of concept" study to evaluate the efficacy of dietary methionine restriction (MR) in humans with metabolic syndrome. METHODS: Twenty-six obese subjects (six male and 20 female) meeting criteria for metabolic syndrome were randomized to a diet restricted to 2 mg methionine/kg body weight per day and were provided capsules containing either placebo (n = 12) or 33 mg methionine/kg body weight per day (n = 14). Energy expenditure, body composition, insulin sensitivity, and biomarkers of metabolic syndrome were measured before and after 16 wk on the respective diets. RESULTS: Insulin sensitivity and biomarkers of metabolic syndrome improved comparably in both dietary groups. Rates of energy expenditure were unaffected by the diets, but dietary MR produced a significant increase in fat oxidation (MR, 12.1 ± 6.0% increase; control, 8.1 ± 3.3% decrease) and reduction in intrahepatic lipid content (MR liver/spleen attenuation ratio, 8.1 ± 3.3% increase; control ratio, 2.2 ± 2.1% increase) that was independent of the comparable reduction in weight and adiposity that occurred in both groups. CONCLUSIONS: Sixteen weeks of dietary MR in subjects with metabolic syndrome produced a shift in fuel oxidation that was independent of the weight loss, decreased adiposity, and improved insulin sensitivity that was common to both diets.

Dietary methionine restriction enhances metabolic flexibility and increases uncoupled respiration in both fed and fasted states.

Dietary methionine restriction (MR) is a mimetic of chronic dietary restriction (DR) in the sense that MR increases rodent longevity, but without food restriction. We report here that MR also persistently increases total energy expenditure (EE) and limits fat deposition despite increasing weight-specific food consumption. In Fischer 344 (F344) rats consuming control or MR diets for 3, 9, and 20 mo, mean EE was 1.5-fold higher in MR vs. control rats, primarily due to higher EE during the night at all ages. The day-to-night transition produced a twofold higher heat increment of feeding (3.0 degrees C vs. 1.5 degrees C) in MR vs. controls and an exaggerated increase in respiratory quotient (RQ) to values greater than 1, indicative of the interconversion of glucose to lipid by de novo lipogenesis. The simultaneous inhibition of glucose utilization and shift to fat oxidation during the day was also more complete in MR (RQ approximately 0.75) vs. controls (RQ approximately 0.85). Dietary MR produced a rapid and persistent increase in uncoupling protein 1 expression in brown (BAT) and white adipose tissue (WAT) in conjunction with decreased leptin and increased adiponectin levels in serum, suggesting that remodeling of the metabolic and endocrine function of adipose tissue may have an important role in the overall increase in EE. We conclude that the hyperphagic response to dietary MR is matched to a coordinated increase in uncoupled respiration, suggesting the engagement of a nutrient-sensing mechanism, which compensates for limited methionine through integrated effects on energy homeostasis.

Role of beta-adrenergic receptors in the hyperphagic and hypermetabolic responses to dietary methionine restriction.

Dietary methionine restriction (MR) limits fat deposition and decreases plasma leptin, while increasing food consumption, total energy expenditure (EE), plasma adiponectin, and expression of uncoupling protein 1 (UCP1) in brown and white adipose tissue (BAT and WAT). beta-adrenergic receptors (beta-AR) serve as conduits for sympathetic input to adipose tissue, but their role in mediating the effects of MR on energy homeostasis is unclear. Energy intake, weight, and adiposity were modestly higher in beta(3)-AR(-/-) mice on the Control diet compared with wild-type (WT) mice, but the hyperphagic response to the MR diet and the reduction in fat deposition did not differ between the genotypes. The absence of beta(3)-ARs also did not diminish the ability of MR to increase total EE and plasma adiponectin or decrease leptin mRNA, but it did block the MR-dependent increase in UCP1 mRNA in BAT but not WAT. In a further study, propranolol was used to antagonize remaining beta-adrenergic input (beta(1)- and beta(2)-ARs) in beta(3)-AR(-/-) mice, and this treatment blocked >50% of the MR-induced increase in total EE and UCP1 induction in both BAT and WAT. We conclude that signaling through beta-adrenergic receptors is a component of the mechanism used by dietary MR to increase EE, and that beta(1)- and beta(2)-ARs are able to substitute for beta(3)-ARs in mediating the effect of dietary MR on EE. These findings are consistent with the involvement of both UCP1-dependent and -independent mechanisms in the physiological responses affecting energy balance that are produced by dietary MR.

Association of prediagnostic serum vitamin D levels with the development of basal cell carcinoma.

We investigated the association between serum 25-hydroxyvitamin D (25(OH)D) levels and basal cell carcinoma (BCC) risk in a nested case-control study at Kaiser Permanente Northern California (KPNC). A total of 220 case patients with BCC diagnosed after serum collection were matched to 220 control subjects. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression. Fully adjusted models included body mass index (BMI), smoking, education, sun-exposure variables, X-ray exposure, and personal history of cancer. For each measure of serum 25(OH)D (continuous, clinically relevant tertiles, quintiles), we found an increased risk of BCC in unadjusted models (OR=1.03, 95% CI 1.00-1.05, P<0.05; OR=3.98, 95% CI: 1.31-12.31, deficient vs. sufficient, test for trend P-value <0.01; OR=2.32, 95% CI: 1.20-4.50, 1st vs. 5th quintile, test for trend P-value 0.03). In fully adjusted models, the values attenuated slightly (OR=1.02, 95% CI 1.00-1.05, P<0.05; OR=3.61, 95% CI: 1.00-13.10, deficient vs. sufficient, t-trend P=0.03; OR=2.09 1st vs. 5th quintile, 95% CI: 0.95-4.58, t-trend P=0.11). Our findings suggest that higher prediagnostic serum 25(OH)D levels may be associated with increased risk of subsequent BCC. Further studies to evaluate the effect of sun exposure on BCC and serum 25(OH)D levels may be warranted.

Methionine restriction effects on mitochondrial biogenesis and aerobic capacity in white adipose tissue, liver, and skeletal muscle of F344 rats.

Methionine restriction increases life span in rats and mice and reduces age-related accretion of adipose tissue in Fischer 344 rats. Recent reports have shown that adipose tissue mitochondrial content and function are associated with adiposity; therefore, the expression of genes involved in mitochondrial biogenesis and oxidative capacity was examined in white adipose tissue, liver, and skeletal muscle from Fischer 344 rats fed control (0.86% methionine) or methionine-restricted (0.17% methionine) diets for 3 months. Methionine restriction induced transcriptional changes of peroxisome proliferator-activated receptors, peroxisome proliferator-activated receptor coactivators 1alpha and 1beta, and some of their known target genes in all of these tissues. In addition, tissue-specific responses were elicited at the protein level. In inguinal adipose tissue, methionine restriction increased protein levels of peroxisome proliferator-activated receptor and peroxisome proliferator-activated receptor coactivator target genes. It also induced mitochondrial DNA copy number, suggesting mitochondrial biogenesis and corresponding with the up-regulation of citrate synthase activity. In contrast, methionine restriction induced changes in mitochondrial glycerol-3-phosphate dehydrogenase activity and stearoyl-coenzyme A desaturase 1 protein levels only in liver and uncoupling protein 3 and cytochrome c oxidase subunit IV protein levels only in skeletal muscle. No increase in mitochondrial DNA copy number was observed in liver and skeletal muscle despite an increase in mitochondrial citrate synthase activity. The results indicate that adiposity resistance in methionine-restricted rats is associated with mitochondrial biogenesis in inguinal adipose tissue and increased mitochondrial aerobic capacity in liver and skeletal muscle.

Helicobacter pylori infection and development of pancreatic cancer.

BACKGROUND: Infection with Helicobacter pylori is an established risk factor for gastric cancer. Results from two studies suggest that it may also be a risk factor for pancreatic cancer. METHODS: We conducted a nested case control study among 128,992 adult subscribers to the Kaiser Permanente Medical Care Program who had been enrolled in a multiphasic health checkup from 1964 to 1969. Serum collected during the checkup was maintained frozen, and subjects were followed for cancer. Cases consisted of 104 randomly selected subjects among 507 who developed pancreatic cancer in the cohort. Controls consisted of 262 pancreatic cancer-free subjects from a pool of 730 controls previously tested for studies conducted on this cohort. Controls were individually matched to cases on age, gender, race, site, and date of multiphasic health checkup. Control sera were compared with cases for antibodies to H. pylori and the CagA protein. The effects of smoking, alcohol consumption, obesity, and years of education were also investigated. RESULTS: Neither H. pylori [odds ratio (OR), 0.85; 95% confidence interval (95% CI), 0.49-1.48] nor its CagA protein (OR, 0.96; 95% CI, 0.48-1.92) was associated with subsequent development of pancreatic cancer. Smoking (OR, 2.09; 95% CI, 1.17-3.74) and greater number of years of education (OR, 2.13; 95% CI, 1.23-3.69) were risk factors for pancreatic cancer, whereas alcohol consumption and obesity were not. CONCLUSION: Our results suggest that H. pylori infection is not associated with development of pancreatic cancer.

Methionine restriction effects on 11 -HSD1 activity and lipogenic/lipolytic balance in F344 rat adipose tissue.

Methionine restriction (MR) limits age-related adiposity in Fischer 344 (F344) rats. To assess the mechanism of adiposity resistance, the effect of MR on adipose tissue (AT) 11beta-hydroxysteroid dehydrogenase-1 (11beta-HSD1) was examined. MR induced 11beta-HSD1 activity in all ATs, correlating with increased tissue corticosterone. However, an inverse relationship between 11beta-HSD1 activity and adipocyte size was observed. Because dietary restriction controls lipogenic and lipolytic rates, MR's effects on lipogenic and lipolytic enzymes were evaluated. MR increased adipose triglyceride lipase and acetyl-coenzyme A carboxylase (ACC) protein levels but induced ACC phosphorylation at serine residues that render the enzyme inactive, suggesting alterations of basal lipolysis and lipogenesis. In contrast, no changes in basal or phosphorylated hormone-sensitive lipase levels were observed. ACC-phosphorylated sites were specific for AMP-activated protein kinase (AMPK); therefore, AMPK activation was evaluated. Significant differences in AMPKalpha protein, phosphorylation, and activity levels were observed only in retroperitoneal fat from MR rats. No differences in protein kinase A phosphorylation and intracellular cAMP levels were detected. In vitro studies revealed increased lipid degradation and a trend toward increased lipid synthesis, suggesting the presence of a futile cycle. In conclusion, MR disrupts the lipogenic/lipolytic balance, contributing importantly to adiposity resistance in F344 rats.

Serum ghrelin levels and risk of subsequent adenocarcinoma of the esophagus.

OBJECTIVE: Several large studies have shown a negative association between Helicobacter pylori (H. pylori) infection and esophageal adenocarcinoma. Diminution of gastric ghrelin secretion by H. pylori could protect against esophageal malignancy by decreasing appetite, food intake, and acid production, thereby decreasing weight and gastroesophageal reflux. METHODS: We evaluated the association of ghrelin with esophageal adenocarcinoma using a population from a previous nested case-control study. Among 128,992 enrolled in a multiphasic health checkup (MHC) between 1964 and 1969, 52 patients developed esophageal adenocarcinoma by the year 2000. Three random controls from the MHC cohort were matched to each case by age, sex, race, and the date and site of their MHC. Serum samples collected at the MHC had been previously tested for IgG antibodies against H. pylori and the CagA protein. Serum ghrelin concentrations were determined by a commercial EIA on 52% of the initial subjects (31 cases and 79 controls). RESULTS: A concentration of ghrelin greater than 3,200 pg/mL at MHC (fourth quartile) was associated with a lower risk of esophageal cancer (H. pylori and body mass index [BMI] adjusted OR=0.18 [CI 0.04-0.78]). This inverse association was seen only in overweight subjects (BMI>or=25, P value for interaction=0.09). The effects of H. pylori and ghrelin were independent. CONCLUSION: Contrary to the original hypothesis, high rather than low serum ghrelin was associated with protection against esophageal adenocarcinoma but only among overweight subjects.

Methionine restriction decreases visceral fat mass and preserves insulin action in aging male Fischer 344 rats independent of energy restriction.

Reduced dietary methionine intake (0.17% methionine, MR) and calorie restriction (CR) prolong lifespan in male Fischer 344 rats. Although the mechanisms are unclear, both regimens feature lower body weight and reductions in adiposity. Reduced fat deposition in CR is linked to preservation of insulin responsiveness in older animals. These studies examine the relationship between insulin responsiveness and visceral fat in MR and test whether, despite lower food intake observed in MR animals, decreased visceral fat accretion and preservation of insulin sensitivity is not secondary to CR. Accordingly, rats pair fed (pf) control diet (0.86% methinone, CF) to match the food intake of MR for 80 weeks exhibit insulin, glucose, and leptin levels similar to control-fed animals and comparable amounts of visceral fat. Conversely, MR rats show significantly reduced visceral fat compared to CF and PF with concomitant decreases in basal insulin, glucose, and leptin, and increased adiponectin and triiodothyronine. Daily energy expenditure in MR animals significantly exceeds that of both PF and CF. In a separate cohort, insulin responses of older MR animals as measured by oral glucose challenge are similar to young animals. Longitudinal assessments of MR and CF through 112 weeks of age reveal that MR prevents age-associated increases in serum lipids. By 16 weeks, MR animals show a 40% reduction in insulin-like growth factor-1 (IGF-1) that is sustained throughout life; CF IGF-1 levels decline much later, beginning at 112 weeks. Collectively, the results indicate that MR reduces visceral fat and preserves insulin activity in aging rats independent of energy restriction.

Does the association between serum endostatin, an endogenous anti-angiogenic protein, and acute myocardial infarction differ by race?

Endostatin, an endogenous anti-angiogenic protein, has been linked to reduced atherosclerosis in animal models. We conducted a nested case-control study to ascertain whether decreased circulating endostatin might be associated with increased odds of acute myocardial infarction (AMI) and whether this association varied by sex or race. Cases were 211 subjects who subsequently developed AMI, and controls were 173 subjects free of cardiovascular disease matched on age, sex, race and follow-up time. In conditional logistic regression adjusting for traditional risk factors, the odds ratio of AMI per 1 SD increment in endostatin was 0.85 (95% confidence interval, 0.73-1.00). This association varied by race (but not by sex) such that a statistically significant inverse relation was found among Asians and white individuals and a significant positive relation among black individuals. Further research is needed to replicate these findings and to elucidate potential mechanisms for these race/ethnic differences.

Epstein-Barr virus and multiple sclerosis: evidence of association from a prospective study with long-term follow-up.

OBJECTIVE: To determine whether serum titers of anti-Epstein-Barr virus (EBV) antibodies are elevated in blood specimens collected up to 30 years prior to onset of multiple sclerosis (MS). METHODS: Individuals with MS were identified among members of the Kaiser Permanente Northern California health plan who participated in the multiphasic examinations administered between 1965 and 1974. Stored serum samples were used to compare anti-EBV antibody titers in 42 individuals who developed MS with age-matched and sex-matched controls. RESULTS: The geometric mean titers of antibodies to the Epstein-Barr nuclear antigen (EBNA) complex and its component EBNA-1 were significantly higher in the MS cases when compared with matched controls. The relative risk of MS associated with a 4-fold increase in antibody titers was 2.1 (95% confidence interval, 1.1-3.8) for the EBNA complex and 1.8 (95% confidence interval, 1.1-2.9) for EBNA-1. Elevations of antibody titers to the EBNA complex and EBNA-1 among MS cases first occurred between 15 to 20 years before the onset of symptoms and persisted thereafter. CONCLUSION: The elevation of anti-EBV titers is probably an early event in the pathogenesis of MS and is unlikely to be the result of an aspecific immune dysregulation.

Helicobacter pylori infection and the risk of development of esophageal adenocarcinoma.

BACKGROUND: An increase in the incidence of esophageal adenocarcinoma has coincided with a decrease in the prevalence of Helicobacter pylori infection. Whether these 2 phenomena are associated is unknown. METHODS: We conducted a nested case-control study of 128,992 members of an integrated health care system who had participated in a multiphasic health checkup (MHC) during 1964-1969. During follow-up, 52 patients developed esophageal adenocarcinoma. Three randomly chosen control subjects from the MHC cohort were matched to each case subject, on the basis of age at the MHC, sex, race, and the date and site of the MHC. Data on cigarette smoking, alcohol consumption, body mass index (BMI), and education level were obtained at the MHC. Serum samples collected at the MHC were tested for IgG antibodies to H. pylori and to the H. pylori CagA protein. RESULTS: Subjects with H. pylori infections were less likely than uninfected subjects to develop esophageal adenocarcinoma (odds ratio [OR], 0.37 [95% confidence interval (CI), 0.16-0.88]). This significant association was restricted to case subjects and control subjects <50 years old at the MHC (OR, 0.20 [95% CI, 0.06-0.68]). In patients with H. pylori infections, the OR for those who tested positive for IgG antibodies to the CagA protein was similar to that for those who tested negative for it. BMI >/=25 and cigarette smoking were strong independent risk factors for development of esophageal adenocarcinoma. CONCLUSION: The absence of H. pylori infection, independent of cigarette smoking and BMI, is associated with a markedly increased risk of development of esophageal adenocarcinoma.