Cellular senescence induction leads to progressive cell death via the INK4a-RB pathway in naked mole-rats.

Naked mole-rats (NMRs) have exceptional longevity and are resistant to age-related physiological decline and diseases. Given the role of cellular senescence in aging, we postulated that NMRs possess unidentified species-specific mechanisms to prevent senescent cell accumulation. Here, we show that upon induction of cellular senescence, NMR fibroblasts underwent delayed and progressive cell death that required activation of the INK4a-retinoblastoma protein (RB) pathway (termed "INK4a-RB cell death"), a phenomenon not observed in mouse fibroblasts. Naked mole-rat fibroblasts uniquely accumulated serotonin and were inherently vulnerable to hydrogen peroxide (H2 O2 ). After activation of the INK4a-RB pathway, NMR fibroblasts increased monoamine oxidase levels, leading to serotonin oxidization and H2 O2 production, which resulted in increased intracellular oxidative damage and cell death activation. In the NMR lung, induction of cellular senescence caused delayed, progressive cell death mediated by monoamine oxidase activation, thereby preventing senescent cell accumulation, consistent with in vitro results. The present findings indicate that INK4a-RB cell death likely functions as a natural senolytic mechanism in NMRs, providing an evolutionary rationale for senescent cell removal as a strategy to resist aging.

Species-specific formation of paraspeckles in intestinal epithelium revealed by characterization of NEAT1 in naked mole-rat.

Paraspeckles are mammalian-specific nuclear bodies built on the long noncoding RNA NEAT1_2 The molecular mechanisms of paraspeckle formation have been mainly studied using human or mouse cells, and it is not known if the same molecular components are involved in the formation of paraspeckles in other mammalian species. We thus investigated the expression pattern of NEAT1_2 in naked mole-rats (nNEAT1_2), which exhibit extreme longevity and lower susceptibility to cancer. In the intestine, nNEAT1_2 is widely expressed along the entire intestinal epithelium, which is different from the expression of mNeat1_2 that is restricted to the cells of the distal tip in mice. Notably, the expression of FUS, a FET family RNA binding protein, essential for the formation of paraspeckles both in humans and mice, was absent in the distal part of the intestinal epithelium in naked mole-rats. Instead, mRNAs of other FET family proteins EWSR1 and TAF15 were expressed in the distal region. Exogenous expression of these proteins in Fus-deficient murine embryonic fibroblast cells rescued the formation of paraspeckles. These observations suggest that nNEAT1_2 recruits a different set of RNA binding proteins in a cell type-specific manner during the formation of paraspeckles in different organisms.

Inflammatory potential of diet and mortality in Australian adults.

OBJECTIVE: Inflammation is implicated in chronic diseases including cancer and CVD, which are major causes of mortality. Diet can influence inflammation status. We therefore examined whether the inflammatory potential of a person's diet is associated with mortality. DESIGN: The inflammatory potential of the usual diet was assessed by calculating Dietary Inflammatory Index (DII) scores from repeated FFQ data (collected in 1992, 1994 and 1996), placing each participant's diet on a continuum from anti- to pro-inflammatory. DII scores were analysed as a continuous variable and as categories by creating quartile groups. Death registry data were used to ascertain all-cause mortality and separately mortality from CVD, cancers and other causes between 1992 and 2022. Cox proportional hazard regression analysis was used to calculate adjusted hazard ratios (HR) with 95 % CI, comparing higher and lowest quartile groups, or HR change per one DII unit increase. SETTING: Nambour, Australia. PARTICIPANTS: A community-based sample of 1440 adults aged 25-75 years. RESULTS: During follow-up, 488 participants died, including 188 from CVD, 151 from cancer and 170 from other causes. Participants in the most pro-inflammatory diet group were at increased risk of all-cause mortality (HRQ4 v. Q1 = 1·55; 95 % CI 1·19, 2·03; P < 0·001) and other-cause mortality (HRQ4 v. Q1 = 1·69; 95 % CI 1·12, 2·54; P 0·01). A one-unit increase in DII score was associated with a 36 % increased risk of CVD among those younger than 55 years of age (HR for a one-unit increase in DII score 1·36, 95 % CI 1·04, 1·78). The risk of cancer mortality was also increased for those with a more pro-inflammatory diet in age ≤ 55 years (HR for a one-unit increase in DII score 1·20, 95 % CI 1·02, 1·40) and age 56-65 years (HR for a one-unit increase in DII score 1·11, 95 % CI 1·00, 1·23). CONCLUSIONS: A pro-inflammatory diet increases the risk of all-cause mortality. Our results support the promotion of anti-inflammatory diets to help promote longevity.

Association of diet quality and weight increase in adult heart transplant recipients.

BACKGROUND: Understanding the quality of the diet of heart transplant recipients (HTRs) is essential to developing effective dietary interventions for weight control, but relevant evidence is scarce. We investigated diet quality and its association with post-transplant increase in weight adjusted for height (body mass index [BMI]) in Australian HTRs. METHODS: We recruited adult HTRs from Queensland's thoracic transplant clinic, 2020-2021. Study participants completed a 3-day food diary using a smart-phone app. Socio-demographic information was collected by self-administered questionnaire, and height, serial weight and clinical information were obtained from medical records. We calculated the Dietary Approaches to Stop Hypertension (DASH) index based on nine food groups and nutrients (index of 90 indicates highest possible quality), and any changes in BMI (≤ 0 kg m-2 or >0 kg m-2) post-transplantation. Median DASH index values were assessed in relation to sex and BMI change using Mann-Whitney U test. RESULTS: Among 49 consented HTRs, 25 (51%) completed the food diary (median age 48 years, 52% females). Median BMI at enrolment was 27.2 kg m-2; median BMI change since transplant was +3.7 kg m-2. Fruit, vegetable, and whole grain intakes were generally lower than recommended, giving a low overall median DASH index of 30 with no sex differences. HTRs for which the BMI increased post-transplant had significantly lower median DASH indices than those whose BMI did not increase (30 vs. 45, p = 0.013). CONCLUSIONS: The diet quality of HTRs appears suboptimal overall, with fruit and vegetable intakes especially low. HTRs whose BMI increased post-transplant had substantially lower quality diets than HTRs whose BMI did not increase.

Carcinogenesis resistance in the longest-lived rodent, the naked mole-rat.

Certain mammalian species are resistant to cancer, and a better understanding of how this cancer resistance arises could provide valuable insights for basic cancer research. Recent technological innovations in molecular biology have allowed the study of cancer-resistant mammals, despite the fact that they are not the classical model animals, which are easily studied using genetic approaches. Naked mole-rats (NMRs; Heterocephalus glaber) are the longest-lived rodent, with a maximum lifespan of more than 37 years, and almost never show spontaneous carcinogenesis. NMRs are currently attracting much attention from aging and cancer researchers, and published studies on NMR have continued to increase over the past decade. Cancer development occurs via multiple steps and involves many biological processes. Recent research on the NMR as a model for cancer resistance suggests that they possess various unique carcinogenesis-resistance mechanisms, including efficient DNA repair pathways, cell-autonomous resistance to transformation, and dampened inflammatory response. Here, we summarize the molecular mechanisms of carcinogenesis resistance in NMR, which have been uncovered over the past two decades, and discuss future perspectives.

Long-term changes in body weight and serum cholesterol in heart transplant recipients.

INTRODUCTION: Long-term changes in weight and blood lipids beyond 12 months after heart transplantation are largely unknown. We quantified changes in weight, body mass index (BMI), blood cholesterol, and triglycerides in heart transplant recipients (HTRs) during the 36 months after transplantation, and we assessed the influence of statin therapy on these outcomes. METHODS: Retrospective cohort study of adult HTRs, transplanted 1990-2017, in Queensland, Australia. From each patient's medical charts, we extracted weight, total cholesterol, triglycerides, and statin therapy at four time-points: time of transplant (baseline), and 12-, 24-, 36-month post-transplant. Changes in weight and blood lipids were assessed according to baseline BMI. RESULTS: Among 316 HTRs, 236 (median age 52 years, 83% males) with available information were included. During the 36 months post-transplant, all patients gained weight (83.5-90.5 kg; p < .001), especially those with baseline BMI < 25.0 km/m2 (67.9-76.2 kg; p < .001). Mean blood cholesterol (4.60-4.90 mmol/L; p = .004) and mean blood triglycerides (1.79-2.18 mmol/L; p = .006) also increased significantly in all patients, particularly in those with baseline BMI ≥ 25.0 km/m2 but the differences were not significant (total cholesterol 4.42-5.13 mmol/L; triglycerides 1.76-2.47 mmol/L). Total cholesterol was highest in patients not taking statins, and levels differed significantly (p = .010) according to statin dosing changes during the 36 months post-transplant. CONCLUSION: Patients demonstrate significant rises in weight and blood lipids in the 36 months after heart transplantation.

Modifying dietary patterns in cardiothoracic transplant patients to reduce cardiovascular risk: The AMEND-IT Trial.

BACKGROUND: Cardiovascular disease (CVD) is common after cardiothoracic transplantation and causes substantial morbidity. AIMS: To assess feasibility and potential effectiveness of dietary interventions to reduce CVD risk. MATERIALS AND METHODS: In a pilot intervention, we recruited patients from a tertiary hospital and randomly allocated them to a Mediterranean or low-fat diet for 12 months. Feasibility was measured by patient participation, retention, and adherence. Changes in weight, body mass index (BMI), heart rate, blood pressure, glucose markers, and blood lipids were assessed using longitudinal generalized estimating equation regression models with 95% confidence intervals. RESULTS: Of 56 heart and 60 lung transplant recipients, 52 (45%) consented, 41 were randomized, and 39 (95%) completed the study with good adherence to randomized diets. After 12 months, changes in many risk factors were seen in the Mediterranean and low-fat-diet groups, respectively, including mean BMI (-0.5 vs. 0.0 kg/m2 ), systolic/diastolic blood pressure +0.5/+0.1 vs -4.4/-3.5 mmHg; fasting glucose -0.26 vs -0.27 mmol/L; total cholesterol -0.56 vs -0.40 mmol/L. Changes in BMI and systolic/diastolic blood pressure in 49 eligible patients who did not take part were +0.7 kg/m2 and +2.5/+1.8 mmHg. DISCUSSION: Dietary interventions in cardiothoracic transplant patients are feasible and potentially beneficial. CONCLUSION: A definitive nutritional intervention study in these high-risk patients is warranted.

Omega-3 fatty acid intake and decreased risk of skin cancer in organ transplant recipients.

PURPOSE: Organ transplant recipients have over 100-fold higher risk of developing skin cancer than the general population and are in need of further preventive strategies. We assessed the possible preventive effects of omega-3 polyunsaturated fatty acid (PUFA) intake from food on the two main skin cancers, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) in kidney and liver transplant recipients. METHODS: Adult kidney or liver transplant recipients transplanted for at least 1 year and at high risk of skin cancer were recruited from the main transplant hospital in Queensland, 2012-2014 and followed until mid-2016. We estimated their dietary total long-chain omega-3 PUFAs and α-linolenic acid intakes at baseline using a food frequency questionnaire and ranked PUFA intakes as low, medium, or high. Relative risks (RRsadj) of skin cancer adjusted for confounding factors with 95% confidence intervals (CIs) were calculated. RESULTS: There were 449 transplant recipients (mean age, 55 years; 286 (64%) male). During follow-up, 149 (33%) patients developed SCC (median 2/person; range 1-40) and 134 (30%), BCC. Transplant recipients with high total long-chain omega-3 PUFA compared with low intakes showed substantially reduced SCC tumour risk (RRadj 0.33, 95% CI 0.18-0.60), and those with high α-linolenic acid intakes experienced significantly fewer BCCs (RRadj 0.40, 95% CI 0.22-0.74). No other significant associations were seen. CONCLUSION: Among organ transplant recipients, relatively high intakes of long-chain omega-3 PUFAs and of α-linolenic acid may reduce risks of SCC and BCC, respectively.

Inflammatory Dietary Patterns and Risk of Keratinocyte Cancers in Kidney Transplant Recipients: Prospective Cohort Study.

BACKGROUND: Kidney transplant recipients (KTRs) are at increased risk of cutaneous squamous (SCC) and basal cell carcinomas (BCC) due to immunosuppression and sun exposure. Skin carcinogenesis involves inflammation, and foods that promote inflammation may promote carcinogenesis. METHODS: We prospectively examined the association between pro-inflammatory diets and SCC and BCC incidence in KTRs in Queensland, Australia. We recruited KTRs at high risk of skin cancer (aged ≥18 years and previously affected; or aged ≥40; or immunosuppressed ≥10 years) between 2012 and 2014 and followed up until June 2016. A baseline dietary questionnaire was used to calculate modified-Empirical Dietary Inflammatory Pattern (EDIP) scores to indicate dietary inflammatory capacity; higher scores indicated pro-inflammatory diets. EDIP scores were ranked into 3 groups. Outcomes were histologically confirmed SCC and BCC. Adjusted relative risks (RRadj) and 95% CIs were estimated using negative binomial regression. RESULTS: Among 260 KTRs, 100 (38%) and 93 (36%) developed at least 1 new SCC and BCC, with 426 SCC and 343 BCC diagnosed in the follow-up period. The highest modified-EDIP score group (vs. lowest) were at increased risk of SCC (RRadj 1.79, 95% CI 1.01-3.16) but not BCC. Pro-inflammatory diets may increase SCC but not BCC risk among KTRs. CONCLUSIONS: Inflammatory diets may increase the risk of SCC in KTRs.

Clinical pathways and outcomes of patients with Barrett's esophagus in tertiary care settings: a prospective longitudinal cohort study in Australia, 2008-2016.

BACKGROUND: Clinical services for Barrett's esophagus have been rising worldwide including Australia, but little is known of the long-term outcomes of such patients. Retrospective studies using data at baseline are prone to both selection and misclassification bias. We investigated the clinical characteristics and outcomes of Barrett's esophagus patients in a prospective cohort. METHODS: We recruited patients diagnosed with Barrett's esophagus in tertiary settings across Australia between 2008 and 2016. We compared baseline and follow-up epidemiological and clinical data between Barrett's patients with and without dysplasia. We calculated age-adjusted incidence rates and estimated minimally and fully adjusted hazard ratios (HR) to identify those clinical factors related to disease progression. RESULTS: The cohort comprised 268 patients with Barrett's esophagus (median follow-up 5 years). At recruitment, 224 (84%) had no dysplasia, 44 (16%) had low-grade or indefinite dysplasia (LGD/IND). The age-adjusted incidence of esophageal adenocarcinoma (EAC) was 0.5% per year in LGD/IND compared with 0.1% per year in those with no dysplasia. Risk of progression to high-grade dysplasia/EAC was associated with prior LGD/IND (fully adjusted HR 6.55, 95% confidence interval [CI] 1.96-21.8) but not long-segment disease (HR 1.03, 95%CI 0.29-3.58). CONCLUSIONS: These prospective data suggest presence of dysplasia is a stronger predictor of progression to cancer than segment length in patients with Barrett's esophagus.

Induced Pluripotent Stem Cells from Cancer-Resistant Naked Mole-Rats.

Stem cells play essential roles in the development and tissue homeostasis of animals and are closely associated with carcinogenesis and aging. Also, the somatic cell reprogramming process to induced pluripotent stem (iPS) cells shares several characteristics with carcinogenesis. In this chapter, we focus on iPS cells and the reprogramming process of somatic cells in the naked mole-rat (NMR), the longest-living rodent with remarkable cancer resistance capabilities. NMR somatic cells show resistance to reprogramming induction, and generated NMR-iPS cells have a unique tumor-resistant phenotype. This phenotype is regulated by expressional activation of the tumor suppressor ARF gene and loss-of-function mutation in oncogene ERAS. Notably, it was also found that NMR somatic cells undergo senescence when ARF is suppressed during reprogramming, which would contribute to the resistance to both reprogramming and cancer in NMR somatic cells. Further studies on reprogramming resistance in NMR somatic cells and their concomitant tumor resistance in NMR-iPS cells would contribute to a better understanding of both cancer resistance and delayed aging in NMRs. In addition, NMR-iPS cells can be used as a new and important cell source for advancing research concerning several extraordinary physiological characteristics of NMR. Furthermore, study of NMR-iPS cells could lead to the development of safer regenerative therapies in the future.

Responses to pup vocalizations in subordinate naked mole-rats are induced by estradiol ingested through coprophagy of queen's feces.

Naked mole-rats form eusocial colonies consisting of a single breeding female (the queen), several breeding males, and sexually immature adults (subordinates). Subordinates are cooperative and provide alloparental care by huddling and retrieving pups to the nest. However, the physiological mechanism(s) underlying alloparental behavior of nonbreeders remains undetermined. Here, we examined the response of subordinates to pup voice and the fecal estradiol concentrations of subordinates during the three reproductive periods of the queen, including gestation, postpartum, and nonlactating. Subordinate response to pup voice was observed only during the queen's postpartum and was preceded by an incremental rise in subordinates' fecal estradiol concentrations during the queen's gestation period, which coincided with physiological changes in the queen. We hypothesized that the increased estradiol in the queen's feces was disseminated to subordinates through coprophagy, which stimulated subordinates' responses to pup vocalizations. To test this hypothesis, we fed subordinates either fecal pellets from pregnant queens or pellets from nonpregnant queens amended with estradiol for 9 days and examined their response to recorded pup voice. In both treatments, the subordinates exhibited a constant level of response to pup voice during the feeding period but became more responsive 4 days after the feeding period. Thus, we believe that we have identified a previously unknown system of communication in naked mole-rats, in which a hormone released by one individual controls the behavior of another individual and influences the level of responsiveness among subordinate adults to pup vocal signals, thereby contributing to the alloparental pup care by subordinates.

Melanoma incidence in Australian commercial pilots, 2011-2016.

OBJECTIVES: Occupational exposure to cosmic and ultraviolet radiation may increase airline pilots' risk of cutaneous melanoma. Meta-analyses of available data show a higher than average incidence of melanoma in airline pilots, but the most recent systematic review revealed that few contemporary data are available. Moreover, all relevant studies have been conducted in Northern Hemisphere populations. We therefore aimed to examine if Australian commercial pilots have a raised incidence of melanoma compared with the general population. METHODS: We examined all melanoma histologically diagnosed among Australian-licensed commercial pilots in the period 2011-2016 by manually reviewing de-identified data in the medical records system of the Australian Civil Aviation Safety Authority. We estimated age-specific incidence rates and compared these with corresponding population rates using standardised incidence ratios (SIRs) as measures of relative risk. Expected numbers were calculated by multiplying age- and calendar period-specific person-years (PYs) with corresponding rates from the entire Australian population; 95% CI were calculated assuming a Poisson distribution of the observed cases. RESULTS: In this cohort of Australian-licensed commercial pilots observed for 91 370 PYs, 114 developed a melanoma (51 invasive, 63 in situ). More than 50% of melanomas occurred on the trunk, and the predominant subtype was superficial spreading melanoma. The SIR for invasive melanoma was 1.20 (95% CI 0.89 to 1.55) and for melanoma in situ, 1.39 (95% CI 1.08 to 1.78). CONCLUSION: Australian-licensed commercial pilots have a modestly raised risk of in situ melanoma but no elevation of invasive melanoma compared with the general population.

Gonadal steroid hormone secretion during the juvenile period depends on host-specific microbiota and contributes to the development of odor preference.

The host microbial community is thought to have an important role in the host endocrine system and behavioral phenotype. We investigated chronological changes of levels of gonadal hormones and corticosterone in the feces of 4- to 8-week-old female germ-free (GF) mice, and conducted odor preference test at 8 weeks of age. We further evaluated the developmental impact of the microbial community by analyzing 4-week-old GF mice orally administered the fecal microbiota of specific pathogen-free (SPF) mice or guinea pigs (GF-SPF mice or GF-Guinea pig mice). The fecal estradiol, progesterone, and corticosterone levels of GF mice were lower than those of SPF mice. Furthermore, the increased levels in GF mice were suggested to be caused by colonization of microbiota of SPF mice or guinea pigs. However, the degree of recovery of progesterone and corticosterone by microbiota of guinea pigs was lower than that by SPF mice. In odor preference tests, interestingly, female GF mice preferred female odors to male odors, although this preference was not seen in other mice. These findings suggested that the microbial community plays an important role in the development of the host endocrine system for gonadal hormones and corticosterone, and odor preference in mice.

Absolute versus relative measures of plasma fatty acids and health outcomes: example of phospholipid omega-3 and omega-6 fatty acids and all-cause mortality in women.

PURPOSE: In a well-characterised community-based prospective study, we aimed to systematically assess the differences in associations of plasma omega-3 and omega-6 fatty acid (FA) status with all-cause mortality when plasma FA status is expressed in absolute concentrations versus relative levels. METHODS: In a community sample of 564 women aged 25-75 years in Queensland, Australia, baseline plasma phospholipid FA levels were measured using gas chromatography. Specific FAs analysed were eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid, total long-chain omega-3 FAs, linoleic acid, arachidonic acid, and total omega-6 FAs. Levels of each FA were expressed in absolute amounts (µg/mL) and relative levels (% of total FAs) and divided into thirds. Deaths were monitored for 17 years and hazard ratios and 95% confidence intervals calculated to assess risk of death according to absolute versus relative plasma FA levels. RESULT: In total 81 (14%) women died during follow-up. Agreement between absolute and relative measures of plasma FAs was higher in omega-3 than omega-6 FAs. The results of multivariate analyses for risk of all-cause mortality were generally similar with risk tending to inverse associations with plasma phospholipid omega-3 FAs and no association with omega-6 FAs. Sensitivity analyses examining effects of age and presence of serious medical conditions on risk of mortality did not alter findings. CONCLUSIONS: The directions and magnitude of associations with mortality of absolute versus relative FA levels were comparable. However, plasma FA expressed as absolute concentrations may be preferred for ease of comparison and since relative units can be deduced from absolute units.

Adherence to Mediterranean and low-fat diets among heart and lung transplant recipients: a randomized feasibility study.

BACKGROUND: Heart and lung transplant recipients are at a substantially increased risk of cardiovascular disease (CVD). Since both low-fat and Mediterranean diets can reduce CVD in immunocompetent people at high risk, we assessed adherence among thoracic transplant recipients allocated to one or other of these diets for 12 months. METHODS: Forty-one transplant recipients (20 heart; 21 lung) randomized to a Mediterranean or a low-fat diet for 12 months received diet-specific education at baseline. Adherence was primarily assessed by questionnaire: 14-point Mediterranean diet (score 0-14) and 9-point low-fat diet (score 0-16) respectively, high scores indicating greater adherence. Median scores at baseline, 6 months, 12 months, and 6-weeks post-intervention were compared by dietary group. We further assessed changes in weight, body mass index (BMI) and serum triglycerides from baseline to 12 months as an additional indicator of adherence. RESULTS: In those randomized to a Mediterranean diet, median scores increased from 4 (range 1-9) at baseline, to 10 (range 6-14) at 6-months and were maintained at 12 months, and also at 6-weeks post-intervention (median 10, range 6-14). Body weight, BMI and serum triglycerides decreased over the 12-month intervention period (mean weight - 1.8 kg, BMI -0.5 kg/m2, triglycerides - 0.17 mmol/L). In the low-fat diet group, median scores were 11 (range 9-14) at baseline; slightly increased to 12 (range 9-16) at 6 months, and maintained at 12 months and 6 weeks post-intervention (median 12, range 8-15). Mean changes in weight, BMI and triglycerides were - 0.2 kg, 0.0 kg/m2 and - 0.44 mmol/L, respectively. CONCLUSIONS: Thoracic transplant recipients adhered to Mediterranean and low-fat dietary interventions. The change from baseline eating habits was notable at 6 months; and this change was maintained at 12 months and 6 weeks post-intervention in both Mediterranean diet and low-fat diet groups. Dietary interventions based on comprehensive, well-supported education sessions targeted to both patients and their family members are crucial to success. Such nutritional strategies can help in the management of their substantial CVD risk. TRIAL REGISTRATION: The IRAS trial registry ( ISRCTN63500150 ). Date of registration 27 July 2016. Retrospectively registered.

Greater Amino Acid Intake Is Required to Maximize Whole-Body Protein Synthesis Immediately after Endurance Exercise Than at Rest in Endurance-Trained Rats, as Determined by an Indicator Amino Acid Oxidation Method.

BACKGROUND: The indicator amino acid oxidation (IAAO) method has contributed to establishing protein and amino acid (AA) requirements by determining the optimal protein and AA intake that maximizes whole-body protein synthesis. However, it has not been used with endurance-trained subjects. OBJECTIVE: This study aimed to determine the optimal AA intake immediately after endurance exercise and at rest in endurance-trained rats by using the IAAO method. METHODS: Four-week-old male Fischer rats were divided into a sedentary (SED) group and a trained (TR) group, which underwent treadmill training 5 d/wk for 6 wk at 26 m/min for 60 min/d. On the metabolic trial day, half of the TR group was provided with test diets after daily treadmill running (TR-PostEx). The other half of the TR group (TR-Rest) and all of the SED group were provided with test diets while at rest. The test diets contained different amounts of AAs (3.3-37.3 g ⋅ kg(-1) ⋅ d(-1)). Phenylalanine in the test diet was replaced with L-[1-(13)C]phenylalanine. The phenylalanine oxidation rate (PheOx) was determined with (13)CO2 enrichment in breath, CO2 excretion rate, and enrichment of phenylalanine in blood during the feeding period. The optimal AA intake was determined with biphasic mixed linear regression crossover analysis for PheOx, which identified a breakpoint at the minimal PheOx in response to graded amounts of AA intake. RESULTS: The optimal AA intake in the TR-PostEx group (26.8 g ⋅ kg(-1) ⋅ d(-1); 95% CI: 21.5, 32.1 g ⋅ kg(-1) ⋅ d(-1)) was significantly higher than in the SED (15.1 g ⋅ kg(-1) ⋅ d(-1); 95% CI: 11.1, 19.1 g ⋅ kg(-1) ⋅ d(-1)) and TR-Rest (13.3 g ⋅ kg(-1) ⋅ d(-1); 95% CI: 10.9, 15.7 g ⋅ kg(-1) ⋅ d(-1)) groups, which did not differ. CONCLUSIONS: Greater AA intake is required to maximize whole-body protein synthesis immediately after endurance exercise than at rest, but not at rest in endurance-trained rats.

Leucine-enriched essential amino acids attenuate inflammation in rat muscle and enhance muscle repair after eccentric contraction.

Eccentric exercise results in prolonged muscle damage that may lead to muscle dysfunction. Although inflammation is essential to recover from muscle damage, excessive inflammation may also induce secondary damage, and should thus be suppressed. In this study, we investigated the effect of leucine-enriched essential amino acids on muscle inflammation and recovery after eccentric contraction. These amino acids are known to stimulate muscle protein synthesis via mammalian target of rapamycin (mTOR), which, is also considered to alleviate inflammation. Five sets of 10 eccentric contractions were induced by electrical stimulation in the tibialis anterior muscle of male SpragueDawley rats (8-9 weeks old) under anesthesia. Animals received a 1 g/kg dose of a mixture containing 40 % leucine and 60 % other essential amino acids or distilled water once a day throughout the experiment. Muscle dysfunction was assessed based on isometric dorsiflexion torque, while inflammation was evaluated by histochemistry. Gene expression of inflammatory cytokines and myogenic regulatory factors was also measured. We found that leucine-enriched essential amino acids restored full muscle function within 14 days, at which point rats treated with distilled water had not fully recovered. Indeed, muscle function was stronger 3 days after eccentric contraction in rats treated with amino acids than in those treated with distilled water. The amino acid mix also alleviated expression of interleukin-6 and impeded infiltration of inflammatory cells into muscle, but did not suppress expression of myogenic regulatory factors. These results suggest that leucine-enriched amino acids accelerate recovery from muscle damage by preventing excessive inflammation.

Dietary Antioxidants and Melanoma: Evidence from Cohort and Intervention Studies.

Melanoma is the most serious form of skin cancer affecting mostly people of Caucasian origin and is associated with high exposure to solar ultraviolet (UV) radiation. Antioxidants in the diet are thought to prevent UV-induced DNA damage and oxidative stress and laboratory-based studies have shown that high antioxidant intakes inhibit melanoma development. Corresponding epidemiological evidence is inconsistent, however. We therefore reviewed results from prospective observational studies and randomized controlled trials (RCTs) to clarify whether consumption of antioxidant vitamin C, E (tocopherol), and A (retinol), carotenoids and selenium, as food, supplements, or both, or high fruit and vegetable intake, reduce the incidence of cutaneous melanoma. A total of 9 studies (2 cohort, 1 nested case-control, 6 RCTs) were included. Neither antioxidant nutrients, individually or combined, nor fruit and vegetable intake showed any strong and significant associations with melanoma, though the number of relevant studies was limited and several had methodological shortcomings. In particular, melanoma was not a primary disease outcome in any of the RCTs and therefore, none adequately accounted for potential confounding by sun exposure. In conclusion, available evidence is currently inadequate to assess possible beneficial effects of antioxidant intake on melanoma risk.