Cumulative Consumption of Sulfur Amino Acids and Risk of Diabetes: A Prospective Cohort Study.

BACKGROUND: Cross-sectional studies have suggested that consumption of sulfur amino acids (SAAs), including methionine and cysteine, is associated with a higher risk of type 2 diabetes (T2D) in humans and with T2D-related biomarkers in animals. But whether higher long-term SAA intake increases the risk of T2D in humans remains unknown. OBJECTIVES: We aimed to investigate the association between long-term dietary SAA intake and risk of T2D. METHODS: We analyzed data collected from 2 different cohorts of the Framingham Heart Study, a long-term, prospective, and ongoing study. The Offspring cohort (1991-2014) included participants from fifth through ninth examinations, and the Third-Generation cohort (2002-2011) included participants from first and second examinations. After excluding participants with a clinical history of diabetes, missing dietary data, or implausible total energy intake, 3222 participants in the Offspring cohort and 3205 participants in the Third-Generation cohort were included. Dietary intake was assessed using a validated FFQ. The relations between energy-adjusted total SAA (methionine and cysteine) intake or individual SAA intake (in quintiles) and risk of incident T2D were estimated via Cox proportional hazards models after adjusting for dietary and nondietary risk factors. Associations across the 2 cohorts were determined by direct combination and meta-analysis. RESULTS: During the 23 y of follow-up, 472 participants reported a new diagnosis of T2D in the 2 cohorts. In the meta-analysis, the HRs of T2D comparing the highest with the lowest intake of total SAAs, methionine, and cysteine were 1.8 (95% CI: 1.3, 2.5), 1.7 (95% CI: 1.2, 2.3), and 1.4 (95% CI: 1.0, 2.1), respectively. The association of SAA intake with T2D was attenuated after adjusting animal protein intake in sensitivity analyses. CONCLUSIONS: Our findings show that excess intake of SAAs is associated with higher risk of T2D. Dietary patterns that are low in SAAs could help in preventing T2D.

Dietary methionine restriction in mice elicits an adaptive cardiovascular response to hyperhomocysteinemia.

Dietary methionine restriction (MR) in rodents increased lifespan despite higher heart-to-body weight ratio (w/w) and hyperhomocysteinemia, which are symptoms associated with increased risk for cardiovascular disease. We investigated this paradoxical effect of MR on cardiac function using young, old, and apolipoprotein E-deficient (ApoE-KO) mice. Indeed, MR animals exhibited higher heart-to-body weight ratio (w/w) and hyperhomocysteinemia with a molecular pattern consistent with cardiac stress while maintaining the integrity of cardiac structure. Baseline cardiac function, which was measured by non-invasive electrocardiography (ECG), showed that young MR mice had prolonged QRS intervals compared with control-fed (CF) mice, whereas old and ApoE-KO mice showed similar results for both groups. Following ß-adrenergic challenge, responses of MR mice were either similar or attenuated compared with CF mice. Cardiac contractility, which was measured by isolated heart retrograde perfusion, was similar in both groups of old mice. Finally, the MR diet induced secretion of cardioprotective hormones, adiponectin and fibroblast growth factor 21 (FGF21), in MR mice with concomitant alterations in cardiac metabolic molecular signatures. Our findings demonstrate that MR diet does not alter cardiac function in mice despite the presence of hyperhomocysteinemia because of the adaptive responses of increased adiponectin and FGF21 levels.

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.

Effects of monopolar radiofrequency treatment over soft-tissue fillers in an animal model.

BACKGROUND AND OBJECTIVES: Monopolar radiofrequency (RF) treatment is used by physicians to tighten and contour the skin of their patients. In many cases, patients have received prior treatment with other aesthetic modalities such as soft-tissue augmentation or they may wish to receive these treatment modalities simultaneously. Together, soft-tissue augmentation and monopolar RF treatment have the potential to restore tissue volume and improve facial laxity. To date, no published studies have documented the effects of RF treatment directly over soft-tissue fillers. STUDY DESIGN/MATERIALS AND METHODS: We examined the tissue interactions of monopolar RF heating with five commonly injected fillers in a juvenile pig model. This is the first part of a two-part study. In this study, the interaction of monopolar RF and filler substances was examined over a period of 4 months. The five soft-tissue fillers examined were cross-linked human collagen (Cosmoplast), hyaluronic acid (Restylane), calcium hydroxylapatite (Radiesse), polylactic acid (Sculptra), and liquid injectable silicone (Silikon 1000). RESULTS: There was no apparent increase in the risk of local burns and no observable effect of RF treatment on filler persistence in the tissue. With monopolar RF treatment, an increase in fibroplasia and collagen deposition surrounding Restylane, Radiesse, and Sculptra was observed. When scored in a blinded fashion, the increase in collagen deposition was statistically significant for Radiesse. CONCLUSIONS: In this animal study, RF treatment had no observed adverse effect on filler collagen responses or persistence. Filler presence did not increase the risk of undesirable thermal effects with monopolar RF treatment. Further clinical studies are required to evaluate the effect of monopolar RF treatment over dermal fillers with respect to aesthetic outcome.

Highly purified 1000-cSt silicone oil for treatment of human immunodeficiency virus-associated facial lipoatrophy: an open pilot trial.

BACKGROUND: Among human immunodeficiency virus-infected individuals, facial lipoatrophy has become epidemic. Those affected are stigmatized, leading to psychological distress, social and career impediments, and impaired compliance to human immunodeficiency virus medications. Temporary treatment options are limited by excessive cost, necessity of frequent treatments, and lack of a natural look or feel beneath the skin. Affected patients require more persistent, affordable, safe, and effective treatment options. OBJECTIVE: The objective was to evaluate the safety and efficacy of highly purified 1000-cSt silicone oil injected by microdroplet serial puncture technique for the treatment of human immunodeficiency virus-associated lipoatrophy. METHODS: Data on 77 patients with a complete correction were analyzed to determine the number of treatments, amount of silicone, and time required to reach complete correction, relative to initial severity. RESULTS: The volume of silicone, number of treatments, and time required to reach a complete correction were directly related to initial severity of lipoatrophy (p < 0.0001). Supple, even facial contours were routinely restored, with all patients tolerating treatments well. No adverse events were noted. CONCLUSION: In this pilot trial, we have demonstrated that highly purified 1000-cSt silicone oil is a safe and effective treatment option for human immunodeficiency virus facial lipoatrophy. Longer-term safety and efficacy in human immunodeficiency virus patients remain to be proven.

A case of HIV-associated facial lipoatrophy treated with 1000-cs liquid injectable silicone.

BACKGROUND: Patients infected with the HIV may experience HIV-associated lipodystrophy, a symptom of which is facial lipoatrophy, a dramatic loss of subcutaneous facial tissue. This visible manifestation of HIV infection causes significant psychosocial pain for patients and has been associated with impaired compliance with medical regimens. OBJECTIVE: To improve the appearance of facial lipoatrophy in a safe, long-lasting, expeditious, and relatively economical manner. METHODS: An HIV-associated lipodystrophy patient with facial lipoatrophy underwent multiple sessions of soft-tissue augmentation therapy with liquid injectable silicone (LIS) using the microdroplet serial puncture technique. RESULTS: Administration of LIS by the microdroplet serial puncture technique produced satisfactory improvement of areas of facial atrophy. The treatment time is limited, the patient discomfort and morbidity are minimal, and results are long lasting. Patients report significant satisfaction with treatment. CONCLUSION: LIS administered by the microdroplet serial puncture technique is a safe and effective method for treating HIV-associated facial lipoatrophy and compares favorably with other methods of tissue augmentation.