Mazen J. Hamadeh

Summary: Caffeine is the most widely used psychostimulant in Western countries, with antioxidant, anti‐inflammatory and anti‐apoptotic properties. In Alzheimer's disease (AD), caffeine is beneficial in both men and women, in humans and animals. Similar effects of caffeine were observed in men with Parkinson's disease (PD); however, the effect of caffeine in femalePDpatients is controversial due to caffeine's competition with estrogen for the estrogen‐metabolizing enzyme,CYP1A2. Studies conducted in animal models ofamyotrophic lateral sclerosis (ALS)showed protective effects of A_2ARantagonism. A study found caffeine to be associated with earlier age of onset of Huntington's disease (HD) at intakes >190 mg/d, but studies in animal models have found equivocal results. Caffeine is protective inADandPDat dosages equivalent to 3‐5 mg/kg. However, further research is needed to investigate the effects of caffeine onPDin women. As well, the effects of caffeine inALS,HDand Machado‐Joseph disease need to be further investigated. Caffeine's most salient mechanisms of action relevant to neurodegenerative diseases need to be further explored.

Dietary vitamin D₃ (D₃) restriction reduces paw grip endurance and motor performance in G93A mice, and increases inflammation and apoptosis in the quadríceps of females. ALS, a neuromuscular disease, causes progressive degeneration of motor neurons in the brain and spinal cord. We analyzed the spinal cords of G93A mice following dietary D₃ restriction at 2.5% the adequate intake (AI) for oxidative damage (4-HNE, 3-NY), antioxidant enzymes (SOD2, catalase, GPx1), inflammation (TNF-α, IL-6, IL-10), apoptosis (bax/bcl-2 ratio, cleaved/pro-caspase 3 ratio), neurotrophic factor (GDNF) and neuron count (ChAT, SMI-36/SMI-32 ratio). Beginning at age 25 d, 42 G93A mice were provided food ad libitum with either adequate (AI;1 IU D₃/g feed; 12 M, 11 F) or deficient (DEF; 0.025 IU D₃/g feed; 10 M, 9 F) D₃. At age 113 d, the spinal cords were analyzed for protein content. Differences were considered significant at P ≤ 0.10, since this was a pilot study. DEF mice had 16% higher 4-HNE (P = 0.056), 12% higher GPx1 (P = 0.057) and 23% higher Bax/Bcl2 ratio (P = 0.076) vs. AI. DEF females had 29% higher GPx1 (P = 0.001) and 22% higher IL-6 (P = 0.077) vs. AI females. DEF males had 23% higher 4-HNE (P = 0.066) and 18% lower SOD2 (P = 0.034) vs. AI males. DEF males had 27% lower SOD2 (P = 0.004), 17% lower GPx1 (P = 0.070), 29% lower IL-6 (P = 0.023) and 22% lower ChAT (P = 0.082) vs. DEF females. D₃ deficiency exacerbates disease pathophysiology in the spinal cord of G93A mice, the exact mechanisms are sex-specific. This is in accord with our previous results in the quadriceps, as well as functional and disease outcomes.

Summary: VitaminDhas been demonstrated to influence multiple aspects of amyotrophic lateral sclerosis (ALS) pathology. Both human and rodent central nervous systems express the vitaminDreceptor (VDR) and/or its enzymatic machinery needed to fully activate the hormone. Clinical research suggests that vitaminDtreatment can improve compromised human muscular ability and increase muscle size, supported by loss of motor function and muscle mass in animals followingVDRknockout, as well as increased muscle protein synthesis andATPproduction following vitaminDsupplementation. VitaminDhas also been shown to reduce the expression of biomarkers associated with oxidative stress and inflammation in patients with multiple sclerosis, rheumatoid arthritis, congestive heart failure,Parkinson's disease andAlzheimer's disease; diseases that share common pathophysiologies withALS. Furthermore, vitaminDtreatment greatly attenuates hypoxic brain damagein vivoand reduces neuronal lethality of glutamate insultin vitro; a hallmark trait ofALSglutamate excitotoxicity. We have recently shown that high‐dose vitaminD₃supplementation improved, whereas vitaminD₃restriction worsened, functional capacity in theG93Amouse model ofALS. In sum, evidence demonstrates that vitaminD, unlike the antiglutamatergic agentRiluzole, affects multiple aspects ofALSpathophysiology and could provide a greater cumulative effect.

The accumulation of intramyocellular lipids (IMCLs) and mitochondrial dysfunction in skeletal muscle have been associated with insulin resistance in obesity. Endurance training (ET) increases mitochondrial content/activity and IMCL content in young, active men and women. We have previously shown that ET alters the size, number, and physical juxtaposition of IMCLs and mitochondria. The purpose of this study was to determine the effects of obesity and ET on mitochondrial function, IMCL content, and IMCL-mitochondria juxtaposition in sedentary lean and obese women. DESIGN, SETTING, SUBJECTS, INTERVENTION, AND MAIN OUTCOME MEASURES: Obese (n = 11) and lean (n = 12), sedentary women were recruited using local advertisements and underwent 12 weeks of ET in our training facility at McMaster University. Blood and muscle biopsy samples (vastus lateralis) were collected before and after ET to measure IMCL and mitochondrial ultrastructure, mitochondrial oxidative capacity, lipid oxidation capacity, and lipid metabolism by-products. Obese women were insulin resistant (homeostasis model assessment of insulin resistance) compared with lean women. ET did not change body weight but increased mitochondrial oxidative and β-oxidation capacity in both groups. ET mediated reorganization of the muscle architecture, whereby IMCL content in the subsarcolemmal region was reduced with a concomitant increase in intermyofibrillar IMCLs. ET increased the percentage of IMCLs in direct contact with mitochondria and did not alter diacylglycerol and ceramide content in either group. ET mediated positive changes in mitochondrial function and lipid oxidation and induced intracellular IMCL reorganization, which is reflective of greater IMCL turnover capacity in both lean and obese women.

Background: Obesity is associated with low-grade systemic inflammation, in part because of secretion of proinflammatory cytokines, resulting into peripheral insulin resistance (IR). Increased oxidative stress is proposed to link adiposity and chronic inflammation. The effects of endurance exercise in modulating these outcomes in insulin-resistant obese adults remain unclear. We investigated the effect of endurance exercise on markers of oxidative damage (4-hydroxy-2-nonenal (4-HNE), protein carbonyls (PCs)) and antioxidant enzymes (superoxide dismutase (SOD), catalase) in skeletal muscle; urinary markers of oxidative stress (8-hydroxy-2-deoxyguanosine (8-OHdG), 8-isoprostane); and plasma cytokines (C-reactive protein (CRP), interleukin-6 (IL-6), leptin, adiponectin). Methods: Age- and fitness-matched sedentary obese and lean men (n=9 per group) underwent 3 months of moderate-intensity endurance cycling training with a vastus lateralis biopsy, 24-h urine sample and venous blood samples taken before and after the intervention. Results: Obese subjects had increased levels of oxidative damage: 4-HNE (+37%; P⩽0.03) and PC (+63%; P⩽0.02); evidence of increased adaptive response to oxidative stress because of elevated levels of copper/zinc SOD (Cu/ZnSOD) protein content (+84%; P⩽0.01); increased markers of inflammation: CRP (+737%; P⩽0.0001) and IL-6 (+85%; P⩽0.03), and these correlated with increased markers of obesity; and increased leptin (+262%; P⩽0.0001) with lower adiponectin (−27%; P⩽0.01) levels vs lean controls. Training reduced 4-HNE (−10%; P⩽0.04), PC (−21%; P⩽0.05), 8-isoprostane (−26%; P⩽0.02) and leptin levels (−33%; P⩽0.01); had a tendency to decrease IL-6 levels (−21%; P=0.07) and IR (−17%; P=0.10); and increased manganese SOD (MnSOD) levels (+47%; P⩽0.01). Conclusion: Endurance exercise reduced skeletal muscle-specific and systemic oxidative damage while improving IR and cytokine profile associated with obesity, independent of weight loss. Hence, exercise is a useful therapeutic modality to reduce risk factors associated with the pathogenesis of IR in obesity.

Lower skeletal muscle mitochondrial oxidative phosphorylation capacity (OXPHOS) and intramyocellular lipid (IMCL) accumulation have been implicated in the etiology of insulin resistance (IR) in obesity. The purpose of this study was to examine the impact of endurance exercise on biochemical and morphological measures of IMCL and mitochondrial content, and their relationship to IR in obese individuals. We examined mitochondrial content (subunit protein abundance and maximal activity of electron transport chain enzymes), IMCL/mitochondrial morphology in both subsarcolemmal (SS) and intermyofibrillar (IMF) regions by transmission electron microscopy, and intracellular lipid metabolites (diacylglycerol and ceramide) in vastus lateralis biopsies, as well as, the homeostasis model assessment index of IR (HOMA-IR) prior to and following twelve weeks of an endurance exercise regimen in healthy age- and physical activity-matched lean and obese men. Obese men did not show evidence of mitochondrial OXPHOS dysfunction, disproportionate IMCL content in sub-cellular regions, or diacylglycerol/ceramide accretion despite marked IR vs. lean controls. Endurance exercise increased OXPHOS and mitochondrial size and density, but not number of individual mitochondrial fragments, with moderate improvements in HOMA-IR. Exercise reduced SS IMCL content (size, number and density), increased IMF IMCL content, while increasing IMCL/mitochondrial juxtaposition in both regions. HOMA-IR was inversely associated with SS (r = −0.34; P = 0.051) and IMF mitochondrial density (r = −0.29; P = 0.096), IMF IMCL/mitochondrial juxtaposition (r = −0.30; P = 0.086), and COXII (r = −0.32; P = 0.095) and COXIV protein abundance (r = −0.35; P = 0.052); while positively associated with SS IMCL size (r = 0.28; P = 0.119) and SS IMCL density (r = 0.25; P = 0.152). Our findings suggest that once physical activity and cardiorespiratory fitness have been controlled for, skeletal muscle mitochondrial and IMCL profile in obesity may only partially contribute to the development of IR.

We previously demonstrated that dietary vitamin D₃ at 10x the adequate intake (AI) attenuates the decline in functional capacity in the G93A mouse model of ALS. We hypothesized that higher doses would elicit more robust changes in functional and disease outcomes. To determine the effects of dietary vitamin D₃ at 50xAI on functional outcomes (motor performance, paw grip endurance) and disease severity (clinical score), as well as disease onset, disease progression and lifespan in the transgenic G93A mouse model of ALS. Starting at age 25 d, 100 G93A mice (55 M, 45 F) were provided ad libitum with either an adequate (AI; 1 IU D₃/g feed) or high (HiD; 50 IU D₃/g feed) vitamin D₃ diet. HiD females consumed 9% less food corrected for body weight vs. AI females (P = 0.010). HiD mice had a 12% greater paw grip endurance over time between age 60–141 d (P = 0.015), and a 37% greater score during disease progression (P = 0.042) vs. AI mice. Although HiD females had a non-significant 31% greater CS prior to disease onset vs. AI females, they exhibited a significant 20% greater paw grip endurance AUC (P = 0.020) when corrected for clinical score. Dietary D₃ supplementation at 50x the adequate intake attenuated the decline in paw grip endurance, but did not influence age at disease onset, hindlimb paralysis or endpoint in the transgenic G93A mouse model of ALS. Furthermore, females may have reached the threshold for vitamin D₃ toxicity as evidence by reduced food intake and greater disease severity prior to disease onset.

It is unclear whether Canadians accurately estimate serving sizes and the number of servings in their diet as intended by Canada’s Food Guide (CFG). The objective of this study was to determine if participants can accurately quantify the size of 1 serving and the number of servings consumed per day. White, Black, South Asian, and East Asian adults (n = 145) estimated the quantity of food that constituted 1 CFG serving, and used CFG to estimate the number of servings that they consumed from their 24-h dietary recall. Participants estimated 1 serving size of vegetables and fruit (+43%) and grains (+55%) to be larger than CFG serving sizes (p ≤ 0.05); meat alternatives (–33%) and cheese (–31%) to be smaller than a CFG serving size (p ≤ 0.05); and chicken, carrots, and milk servings accurately (p > 0.05). Serving size estimates were positively correlated with the amount of food participants regularly consumed at 1 meal (p < 0.001). From their food records, all ethnicities estimated that they consumed fewer servings of vegetables and fruit (–15%), grains (–28%), and meat and alternatives (–14%) than they actually consumed, and more servings of milk and alternatives (+26%, p ≤ 0.05) than they actually consumed. Consequently, 68% of participants believed they needed to increase consumption by greater than 200 kcal to meet CFG recommendations. In conclusion, estimating serving sizes to be larger than what is defined by CFG may inadvertently lead to estimating that fewer servings were consumed and overeating if Canadians follow CFG recommendations without guidance. Thus, revision to CFG or greater public education regarding the dietary guidelines is warranted.

SUMMARY : Background: Vitamin D has antioxidant, anti‐inflammatory, and neuroprotective properties, and may mitigate amyotrophic lateral sclerosis (ALS) pathology.Aims: To determine the effects of dietary vitamin D₃ (D₃) at 10‐fold the adequate intake (AI) on functional and disease outcomes and lifespan in the transgenic G93A mouse model of ALS.Methods: Starting at age 40 days, 32 G93A mice (21 M, 11 F) were provided ad libitum with either an adequate (AI; 1 IU/g feed) or high (HiD; 10 IU/g feed) D₃ diet. Differences were considered significant at P≤ 0.10, as this was a pilot study.Results: For paw grip endurance, HiD mice had a 7% greater score between 60–133 d versus AI mice (P= 0.074). For motor performance, HiD mice had a 22% greater score between 60–133 days (P= 0.074) versus AI mice due to changes observed in male mice, where HiD males had a 33% greater score (P= 0.064) versus AI males. There were no significant diet differences in disease onset, disease progression, or lifespan.Conclusion: Although disease outcomes were not affected, D₃ supplementation at 10‐fold the AI improved paw grip endurance and motor performance in the transgenic G93A mouse model of ALS, specifically in males.

Hippocampal neurogenesis in the subgranular zone (SGZ) of dentate gyrus (DG) occurs throughout life and is regulated by pathological and physiological processes. The role of oxidative stress in hippocampal neurogenesis and its response to exercise or neurodegenerative diseases remains controversial. The present study was designed to investigate the impact of oxidative stress, treadmill exercise and sex on hippocampal neurogenesis in a murine model of heightened oxidative stress (G93A mice). G93A and wild type (WT) mice were randomized to a treadmill running (EX) or a sedentary (SED) group for 1 or 4 wk. Immunohistochemistry was used to detect bromodeoxyuridine (BrdU) labeled proliferating cells, surviving cells, and their phenotype, as well as for determination of oxidative stress (3-NT; 8-OHdG). BDNF and IGF1 mRNA expression was assessed by in situ hybridization. Results showed that: (1) G93A-SED mice had greater hippocampal neurogenesis, BDNF mRNA, and 3-NT, as compared to WT-SED mice. (2) Treadmill running promoted hippocampal neurogenesis and BDNF mRNA content and lowered DNA oxidative damage (8-OHdG) in WT mice. (3) Male G93A mice showed significantly higher cell proliferation but a lower level of survival vs. female G93A mice. We conclude that G93A mice show higher hippocampal neurogenesis, in association with higher BDNF expression, yet running did not further enhance these phenomena in G93A mice, probably due to a ‘ceiling effect’ of an already heightened basal levels of hippocampal neurogenesis and BDNF expression.