The association of dietary antioxidants and the inflammatory potential of the diet with poor physical function and disability in older Australian men: the Concord Health and Ageing in Men Project

Our objective was to evaluate the association of antioxidant intake and the inflammatory potential of the diet with functional decline in older men. A diet history questionnaire was used to collect dietary intake data from men aged ≥ 75 years (n 794) participating in the Concord Health and Aging in Men Project cohort study. Intake of vitamins A, C, E and Zn were compared with the Australian Nutrient Reference Values to determine adequacy. The Energy-adjusted Dietary Inflammatory Index (E-DIITM) was used to assess the inflammatory potential of the diet. Physical performance data were collected via handgrip strength and walking speed tests, and activities of daily living (ADL) and instrumental activities of daily living (IADL) questionnaires, at baseline and 3-year follow-up (n 616). Logistic regression analysis was used to identify associations between diet and incident poor physical function and disability. Both poor antioxidant intake and high E-DII scores at baseline were significantly associated with poor grip strength and ADL disability at 3-year follow-up. No significant associations with walking speed or IADL disability were observed. Individual micronutrient analysis revealed a significant association between the lowest two quartiles of vitamin C intake and poor grip strength. The lowest quartiles of intake for vitamins A, C, E and Zn were significantly associated with incident ADL disability. The study observed that poor antioxidant and anti-inflammatory food intake were associated with odds of developing disability and declining muscle strength in older men. Further interventional research is necessary to clarify the causality of these associations.

Functional profiling of gut microbial and immune responses toward different types of dietary fiber: a step toward personalized dietary interventions

Dietary fiber plays a crucial role in maintaining gut and overall health. The objective of this study was to investigate whether different types of dietary fiber elicited specific changes in gut microbiota composition and the production of short-chain fatty acids. To test this, a longitudinal crossover study design was employed, in which healthy adult women consumed three distinct dietary fiber supplements: Inulin (fructo-oligosaccharide), Vitafiber (isomalto-oligosaccharide), and Fibremax (mixture of different fiber) during a one-week intervention period, followed by a 2-week washout period. A total of 15 g of soluble fiber was consumed daily for each supplement. Samples were collected before and after each intervention to analyze the composition of the gut microbiota by 16S rRNA sequencing and fecal levels of short-chain fatty acids measured using nuclear magnetic resonance. Phenotypic changes in peripheral blood mononuclear cells were studied in subsets of participants with higher SCFA levels post-intervention using spectral flow cytometry. The results revealed substantial stability and resilience of the overall gut bacterial community toward fiber-induced changes. However, each supplement had specific effects on gut bacterial alpha and beta diversity, SCFA production, and immune changes. Inulin consistently exerted the most pronounced effect across individuals and certain taxa were identified as potential indicators of SCFA production in response to inulin supplementation. This distinguishing feature was not observed for the other fiber supplements. Further large-scale studies are required to confirm these findings. Overall, our study implies that personalized dietary fiber intervention could be tailored to promote the growth of beneficial bacteria to maximize SCFA production and associated health benefits.

Associations between protein to non-protein ratio and intakes of other dietary components in a cohort aged 65-75 years: the Nutrition for Healthy Living Study

OBJECTIVE

Diets with a low proportion of energy from protein have shown to cause overconsumption of non-protein energy, known as Protein Leverage. Older adults are susceptible to nutritional inadequacy. The aim was to investigate associations between protein to non-protein ratio (P:NP) and intakes of dietary components and assess the nutritional adequacy of individuals aged 65-75 years from the Nutrition for Healthy Living (NHL) Study.

DESIGN

Cross-sectional. Nutritional intakes from seven-day weighed food records were compared with the Nutrient Reference Values for Australia and New Zealand, Australian Guide to Healthy Eating, Australian Dietary Guidelines and World Health Organisation Free Sugar Guidelines. Associations between P:NP and intakes of dietary components were assessed through linear regression analyses.

SETTING

NHL Study.

PARTICIPANTS

113 participants.

RESULTS

Eighty-eight (59 female and 29 male) with plausible dietary data had a median (interquartile range) age of 69 years (67-71), high education level (86 %) and sources of income apart from the age pension (81 %). Substantial proportions had intakes below recommendations for dairy and alternatives (89 %), wholegrain (89 %) and simultaneously exceeded recommendations for discretionary foods (100 %) and saturated fat (92 %). In adjusted analyses, P:NP (per 1 % increment) was associated with lower intakes of energy, saturated fat, free sugar and discretionary foods and higher intakes of vitamin B12, Zn, meat and alternatives, red meat, poultry and wholegrain % (all P < 0·05).

CONCLUSIONS

Higher P:NP was associated with lower intakes of energy, saturated fat, free sugar and discretionary. Our study revealed substantial nutritional inadequacy in this group of higher socio-economic individuals aged 65-75 years.

Vegetarian Dietary Patterns and Cardiometabolic Risk in People With or at High Risk of Cardiovascular Disease: A Systematic Review and Meta-analysis

IMPORTANCE

Plant-based diets are known to improve cardiometabolic risk in the general population, but their effects on people at high risk of cardiovascular diseases (CVDs) remain inconclusive.

OBJECTIVE

To assess the association of vegetarian diets with major cardiometabolic risk factors, including low-density lipoprotein cholesterol (LDL-C), hemoglobin A1c (HbA1c), systolic blood pressure (SBP), and body weight in people with or at high risk of CVDs.

DATA SOURCES

This meta-analysis was registered before the study was conducted. Systematic searches performed included Embase, MEDLINE, CINAHL, and CENTRAL from inception until July 31, 2021.

STUDY SELECTION

Eligible randomized clinical trials (RCTs) that delivered vegetarian diets in adults with or at high risk of CVDs and measured LDL-C, HbA1c or SBP were included. Of the 7871 records screened, 29 (0.4%; 20 studies) met inclusion criteria.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted data including demographics, study design, sample size, and diet description, and performed risk of bias assessment. A random-effects model was used to assess mean changes in LDL-C, HbA1c, SBP, and body weight. The overall certainty of evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool.

MAIN OUTCOMES AND MEASURES

Mean differences between groups in changes (preintervention vs postintervention) of LDL-C, HbA1c, and SBP; secondary outcomes were changes in body weight and energy intake.

RESULTS

Twenty RCTs involving 1878 participants (range of mean age, 28-64 years) were included, and mean duration of intervention was 25.4 weeks (range, 2 to 24 months). Four studies targeted people with CVDs, 7 focused on diabetes, and 9 included people with at least 2 CVD risk factors. Overall, relative to all comparison diets, meta-analyses showed that consuming vegetarian diets for an average of 6 months was associated with decreased LDL-C, HbA1c, and body weight by 6.6 mg/dL (95% CI, -10.1 to -3.1), 0.24% (95% CI, -0.40 to -0.07), and 3.4 kg (95% CI, -4.9 to -2.0), respectively, but the association with SBP was not significant (-0.1 mm Hg; 95% CI, -2.8 to 2.6). The GRADE assessment showed a moderate level of evidence for LDL-C and HbA1c reduction.

CONCLUSIONS AND RELEVANCE

In this study, consuming a vegetarian diet was associated with significant improvements in LDL-C, HbA1c and body weight beyond standard therapy in individuals at high risk of CVDs. Additional high-quality trials are warranted to further elucidate the effects of healthy plant-based diets in people with CVDs.

Haem Iron Intake Is Associated with Increased Major Adverse Cardiovascular Events, All-Cause Mortality, Congestive Cardiac Failure, and Coronary Revascularisation in Older Men: The Concord Health and Ageing in Men Project

BACKGROUND

Nutritional intake can influence major adverse cardiovascular events (MACE). Dietary iron is found in two forms: haem-iron (HI) only found in animal sources and non-haem iron (NHI) present mostly in plant sources.

OBJECTIVE

We evaluated the associations between dietary iron intakes with MACE and iron status biomarkers.

DESIGN

Prospective cohort study.

SETTING

The Concord Health and Ageing in Men Project, Sydney, Australia.

PARTICIPANTS

539 community-dwelling older Australian men aged 75 years and older.

METHODS

Men underwent nutritional assessment using a validated diet history questionnaire. Entries were converted to food groups and nutrients. The dietary calculation was used to derive HI and NHI intakes from total iron intakes. Analyses of iron intakes with iron status biomarkers were conducted using linear regression, and with MACE and individual endpoints were conducted using Cox regression. Five-point MACE comprised of all-cause mortality, myocardial infarction (MI), congestive cardiac failure (CCF), coronary revascularisation, and/or ischaemic stroke. Four-point MACE included the four endpoints of MI, CCF, coronary revascularisation, and/or ischaemic stroke, and excluded all-cause mortality.

RESULTS

At a median of 5.3 (4.6 - 6.3) years follow-up, the incidences were: 31.2% (n = 168) five-point MACE, 17.8% (n = 96) four-point MACE excluding all-cause mortality, 20.1% (n = 111) all-cause mortality, 11.3% (n = 61) CCF, and 3.1% (n = 15) coronary revascularisation. In adjusted analyses, higher HI intake (per 1mg increment) was associated with increased five-point MACE (HR: 1.45 [95% CI: 1.16, 1.80, P = .001]), four-point MACE excluding all-cause mortality (HR: 1.64 [95% CI: 1.26, 2.15, P <.001]), all-cause mortality (HR: 1.51 [95% CI: 1.15, 1.99, P = .003]), CCF (HR: 2.08 [95% CI: 1.45, 2.98, P <.001]), and coronary revascularisation (HR: 1.89 [95% CI: 1.15, 3.10, P = .012]). Compared with the bottom tertile of NHI intake, the middle tertile of NHI intake was associated with reduced risk of all-cause mortality (HR: 0.56 [95% CI: 0.33, 0.96, P = .035]). Total iron intake was not associated with MACE and individual endpoints. Dietary iron intakes were not associated with serum iron and haemoglobin.

CONCLUSION

Higher haem iron intake was independently associated with increased risks of five-point MACE, four-point MACE excluding all-cause mortality, all-cause mortality, CCF, and coronary revascularisation in older men over 5 years.

Changes in dietary total and non-haem iron intake is associated with incident frailty in older men: The Concord Health and Ageing in Men Project

Background

Nutritional intake could influence the development of frailty. The aim was to evaluate the associations between dietary iron intakes and changes in dietary iron intakes with frailty.

Methods

Cross-sectional analyses involved 785 men with Fried frailty phenotype (FP) and 758 men with Rockwood frailty index (FI) data aged 75 years and older at nutrition assessment from the Concord Health and Ageing in Men Project prospective cohort study. Of these, 563 men who were FP robust or prefrail, and 432 men who were FI nonfrail were included in the longitudinal analyses for more than 3 years. Dietary intake was assessed at both timepoints using a validated diet history questionnaire. The dietary calculation was used to derive heme iron and nonheme iron intakes from total iron intakes. The associations were evaluated through binary logistic regression.

Results

Incidence of FP frailty was 15.3% (n = 86). In longitudinal analyses, maintaining total iron intakes (medium tertile −2.61–0.81 mg/d), increases in total iron and nonheme iron intakes (high tertiles ≥0.82 mg/d and ≥0.80 mg/d), and changes in nonheme iron intake (1 mg increment) were associated with reduced risks of incident FP frailty (OR: 0.47 [95% confindence interval (CI): 0.24, 0.93, p = .031], OR 0.48 [95% CI: 0.23, 0.99, p = .048], OR 0.41 [95% CI: 0.20, 0.88, p = .022], and OR 0.89 [95% CI: 0.82, 0.98, p = .017]).

Conclusion

Maintaining or increases in total dietary iron and increases or changes in dietary nonheme iron intakes more than 3 years were associated with reduced incidence of FP frailty in older men.

A randomised clinical trial to investigate the effect of dietary protein sources on periodontal health

AIM

The aim was to assess two macronutrient interventions in a 2x2 factorial dietary design to determine their effects on oral health.

MATERIALS AND METHODS

Participants (65-75 years old) with a BMI between 20-35 kg/m² of a larger RCT who consented to an oral health assessment were recruited. They had ad libitum access to one of four experimental diets (omnivorous higher fat or higher carbohydrate, semi-vegetarian higher fat or higher carbohydrate) for 4 weeks. Periodontal examination included periodontal probing depth (PPD), clinical attachment level (CAL) and bleeding on probing. Oral plaque and gingival crevicular fluid (GCF) were collected before and after the intervention.

RESULTS

Between baseline and follow up the number of sites with a CAL <5 mm (mean difference (MD) -5.11±9.68, P=0.039) increased and the GCF amount (MD -23.42±39.42 Periotron Units (PU), P=0.050) decreased for the semi-vegetarian high fat diet. For the mean proportion of sites with PPD reduction >1 mm and CAL gain >1 mm significant differences were calculated between the diets investigated. The clinical parameters were not associated with changes of the oral microbiota.

CONCLUSION

The results of this study provided evidence that a semi-vegetarian higher fat diet provides benefits to clinical parameters of periodontal health. ACTRN12616001606471. This article is protected by copyright. All rights reserved.

Essential Hypertension Is Associated With Changes in Gut Microbial Metabolic Pathways: A Multisite Analysis of Ambulatory Blood Pressure

[Figure: see text].

The short- and long-term effects of dietary patterns on cardiometabolic health in adults aged 65 years or older: a systematic review

CONTEXT

Cardiometabolic diseases are leading causes of death and morbidity. Aging increases the risk of disease development. Diet has protective and causal effects on cardiometabolic health.

OBJECTIVE

To consolidate the current evidence on the short- and long-term effects of dietary patterns on cardiometabolic health in adults aged ≥ 65 years.

DATA SOURCES

The Medline, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Scopus, Global Health, and Pre-Medline databases, along with ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform were searched.

DATA EXTRACTION

A total of 40 042 records were identified. Quality assessment involved using the revised Cochrane risk-of-bias tool for randomized trials and Joanna Briggs Institute checklists. The certainty of evidence was assessed using Grading of Recommendations, Assessment, Development, and Evaluation.

RESULTS

Thirteen articles were included (n = 5 cohort studies and n = 3 randomized controlled trials). The low-fat dietary pattern reduced adiposity; however, no effects were evident for hypertension incidence, composite coronary heart disease incidence (including myocardial infarction, coronary heart disease, and coronary revascularization), high-density lipoprotein cholesterol level, and increased blood pressure in the long term. The Mediterranean dietary pattern resulted in reduced triglyceride levels and systolic blood pressure, and had no effects on diastolic blood pressure and glucose in the short term. Other dietary patterns had inconclusive effects.

CONCLUSIONS

The Mediterranean dietary pattern showed the most benefits without harm on cardiometabolic health in older adults. The current body of evidence is small, indicating the need for more research to confirm these findings at a high certainty of evidence, and to include dietary patterns combined with other dietary components, subgroups with cardiometabolic disease or risk factors, longer follow-up, and outcomes that have not yet been investigated. Studies including these factors may help identify the most effective dietary pattern for cardiometabolic health benefits in older adults, to inform future guidelines.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020141400.

The Gut Microbiome of Heart Failure With Preserved Ejection Fraction

Background

Risk factors for heart failure with preserved ejection fraction (HFpEF) include hypertension, age, sex, and obesity. Emerging evidence suggests that the gut microbiota independently contributes to each one of these risk factors, potentially mediated via gut microbial‐derived metabolites such as short‐chain fatty acids. In this study, we determined whether the gut microbiota were associated with HFpEF and its risk factors.

Methods and Results

We recruited 26 patients with HFpEF and 67 control participants from 2 independent communities. Patients with HFpEF were diagnosed by exercise right heart catheterization. We assessed the gut microbiome by bacterial 16S rRNA sequencing and food intake by the food frequency questionnaire. There was a significant difference in α‐diversity (eg, number of microbes) and β‐diversity (eg, type and abundance of microbes) between both cohorts of controls and patients with HFpEF (P=0.001). We did not find an association between β‐diversity and specific demographic or hemodynamic parameters or risk factors for HFpEF. The Firmicutes to Bacteroidetes ratio, a commonly used marker of gut dysbiosis, was lower, but not significantly so (P=0.093), in the patients with HFpEF. Compared with controls, the gut microbiome of patients with HFpEF was depleted of bacteria that are short‐chain fatty acid producers. Consistent with this, participants with HFpEF consumed less dietary fiber (17.6±7.7 versus 23.2±8.8 g/day; P=0.016).

Conclusions

We demonstrate key changes in the gut microbiota in patients with HFpEF, including the depletion of bacteria that generate metabolites known to be important for cardiovascular homeostasis. Further studies are required to validate the role of these gut microbiota and metabolites in the pathophysiology of HFpEF.

Plant-Based Dietary Patterns, Body Composition, Muscle Strength and Function in Middle and Older Age: A Systematic Review

BACKGROUND

Sarcopenia is prevalent in middle-aged and older adults. A plant-based diet may be linked to changes in body composition and musculoskeletal health.

OBJECTIVE

This systematic review aimed to investigate the effects of plant-based dietary patterns on the body composition, muscle strength and function in middle-aged and older adults. PRISMA guidelines were followed.

METHOD

A systematic search was completed on databases including MEDLINE, Embase, Global Health, PREMEDLINE, Cochrane library, CINAHL and Scopus on articles published until 1st March 2019. Search terms included 'middle-aged', 'older adult', 'plant-based diet' and 'muscle strength'. Title and abstract screening were conducted on 1,868 publications after deduplication. Sample size, subject characteristics, recruitment, inclusion and exclusion criteria, dietary measures, health outcome measures, statistical results and confounders were sorted by author, study type, year and country. The quality of evidence of extracted data was assessed using the Scottish Intercollegiate Guidelines Network (SIGN) and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tools.

RESULTS/CONCLUSIONS

17 papers were included from 31 articles selected for full review. The majority of the studies were cross-sectional studies (n = 9) and RCTs (n = 6).The remaining studies were cohort studies. Positive associations were found between plant-based dietary patterns; negative association with body composition; and inconclusive association with muscle function. However, further studies are needed to improve the understanding.

Prospective Associations Between Dietary Antioxidant Intake and Frailty in Older Australian Men: The Concord Health and Ageing in Men Project

BACKGROUND

The objective of the study is to evaluate the prospective associations between antioxidant intake and incident frailty among older Australian men aged ≥75 years.

METHODS

Seven hundred and ninety-four men participated in a detailed diet history interview at the Concord Health and Ageing in Men Project (CHAMP) study third wave (considered baseline nutrition here) and 781 men participated at the fourth wave (considered 3-year follow-up here). The main outcome measurement was incident frailty at 3-year follow-up, using the Cardiovascular Health Study definition. Dietary adequacy of antioxidant intake was assessed by comparing participants' median intakes of four dietary antioxidants (vitamin A, E, C, and zinc) to the nutrient reference values (NRVs). Attainment of the NRVs was incorporated into a dichotomized variable "poor" (meeting ≤2 antioxidants) or "good" (meeting ≥3 antioxidants) as the independent variable using the cut-point method. Also, intakes of each individual dietary antioxidant at baseline nutrition were categorized into quartiles. Analyses were performed using multinomial logistic regression.

RESULTS

Incidence of pre-frailty was 53.0% and frailty was 6.4% at 3-year follow-up. Poor dietary antioxidant intake (meeting ≤2) at baseline nutrition was associated with incident frailty at 3-year follow-up in unadjusted (OR: 2.59 [95% CI: 1.47, 4.59, p = .001]) and adjusted (OR: 2.46 [95% CI: 1.10, 5.51, p = .03]) analyses. The lowest quartile of vitamin E intake (<7.08 mg/d) was significantly associated with incident frailty (OR: 2.46 [95% CI: 1.01, 6.00, p = .05]).

CONCLUSIONS

Poor antioxidant intake, particularly vitamin E, is a plausible factor associated with incident frailty among older men. This supports the need for clinical trials of diets rich in antioxidants or possibly low-dose antioxidant supplements, for prevention of frailty.

Proinflammatory Diet Increases Circulating Inflammatory Biomarkers and Falls Risk in Community-Dwelling Older Men

BACKGROUND

The relations between diet, chronic inflammation, and musculoskeletal health are unclear, especially among older men.

OBJECTIVE

This study aimed to determine associations of the Dietary Inflammatory Index (DII) with inflammatory biomarkers, musculoskeletal health, and falls risk in community-dwelling older men.

METHODS

The cross-sectional analysis included 794 community-dwelling men, mean age 81.1 ± 4.5 y, who participated in the 5-y follow-up of the Concord Health and Aging in Men Project. Of these, 616 were seen again 3 y later for the longitudinal analysis. Energy-adjusted DII (E-DII) was calculated from a validated diet history questionnaire. Bone mineral density (BMD) was measured using DXA. Twenty-four inflammatory biomarkers were analyzed. Incident falls over 3 y were determined through telephone interviews every 4 mo. Multiple regression, linear mixed effects models, negative binomial regression, and mediation analysis were utilized in this study.

RESULTS

A higher E-DII score (indicating a more proinflammatory diet) was associated with higher concentrations of IL-6 (β: 0.028 pg/mL; 95% CI: 0.003, 0.053), IL-7 (β: 0.020 pg/mL; 95% CI: 0.002, 0.037), and TNF-α (β: 0.027 pg/mL; 95% CI: 0.003, 0.051). A higher E-DII score was also associated with lower appendicular lean mass adjusted for BMI (ALMBMI) (β: -0.006 kg/m2; 95% CI: -0.010, -0.001). For every unit increase in E-DII (range: -4.91 to +3.66 units), incident falls rates increased by 13% (incidence rate ratio: 1.13; 95% CI: 1.05, 1.21) over 3 y. Mediation analysis showed that the association between E-DII and 3-y incident falls was influenced by the concentrations of IL-7 by 24%. There was no association between E-DII and BMD.

CONCLUSIONS

Consumption of a proinflammatory diet was associated with increased concentrations of IL-6, IL-7, and TNF-α; increased falls risk; and lower ALMBMI in community-dwelling older men. The association between incident falls and E-DII was partly mediated by concentrations of IL-7.

Of Older Mice and Men: Branched-Chain Amino Acids and Body Composition

Protein and branched-chain amino acid (BCAA) intake are associated with changes in circulating BCAAs and influence metabolic health in humans and rodents. However, the relationship between BCAAs and body composition in both species is unclear, with many studies questioning the translatability of preclinical findings to humans. Here, we assessed and directly compared the relationship between circulating BCAAs, body composition, and intake in older mice and men. Body weight and body fat were positively associated with circulating BCAA levels in both mouse and human, which remained significant after adjustments for age, physical activity, number of morbidities, smoking status, and source of income in the human cohort. Macronutrient intakes were similarly associated with circulating BCAA levels; however, the relationship between protein intake and BCAAs were more pronounced in the mice. These findings indicate that the relationship between circulating BCAAs, body composition, and intakes are comparable in both species, suggesting that the mouse is an effective model for examining the effects of BCAAs on body composition in older humans.

Aging, lifestyle and dementia

Aging is the greatest risk factor for most diseases including cancer, cardiovascular disorders, and neurodegenerative disease. There is emerging evidence that interventions that improve metabolic health with aging may also be effective for brain health. The most robust interventions are non-pharmacological and include limiting calorie or protein intake, increasing aerobic exercise, or environmental enrichment. In humans, dietary patterns including the Mediterranean, Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) and Okinawan diets are associated with improved age-related health and may reduce neurodegenerative disease including dementia. Rapamycin, metformin and resveratrol act on nutrient sensing pathways that improve cardiometabolic health and decrease the risk for age-associated disease. There is some evidence that they may reduce the risk for dementia in rodents. There is a growing recognition that improving metabolic function may be an effective way to optimize brain health during aging.

SUMCOR: Cascade summing correction for volumetric sources applying MCNP6

The main features of code SUMCOR developed for cascade summing correction for volumetric sources are described. MCNP6 is used to track histories starting from individual points inside the volumetric source, for each set of cascade transitions from the radionuclide. Total and FEP efficiencies are calculated for all gamma-rays and X-rays involved in the cascade. Cascade summing correction is based on the matrix formalism developed by Semkow et al. (1990). Results are presented applying the experimental data sent to the participants of two intercomparisons organized by the ICRM-GSWG and coordinated by Dr. Marie-Cristine Lépy from the Laboratoire National Henri Becquerel (LNE-LNHB), CEA, in 2008 and 2010, respectively and compared to the other participants in the intercomparisons.

Cyclic electron flow, NPQ and photorespiration are crucial for the establishment of young plants of Ricinus communis and Jatropha curcas exposed to drought

Although plant physiological responses to drought have been widely studied, the interaction between photoprotection, photorespiration and antioxidant metabolism in water-stressed plants is scarcely addressed. This study aimed to evaluate the physiological adjustments preserving photosynthesis and growth in two plant species with different tolerance to drought: Jatropha curcas and Ricinus communis. We measured stress indicators, gas exchange, photochemistry of PSII and PSI, antioxidant enzymes, cyclic electron flow and photorespiration. Physiological stress indicators associated with reduction in growth confirmed R. communis as sensitive and J. curcas as tolerant to drought. Drought induced loss of photosynthesis in R. communis, whereas J. curcas maintained higher leaf gas exchange and photochemistry under drought. In addition, J. curcas showed higher dissipation of excess energy and presented higher cyclic electron flow when exposed to drought. Although none of these mechanisms have been triggered in R. communis, this species showed increases in photorespiration. R. communis displayed loss of Rubisco content while the Rubisco relative abundance did not change in J. curcas under drought. Accordingly, the in vivo maximum Rubisco carboxylation rate (V_cmax ) and the maximum photosynthetic electron transport rate driving RuBP regeneration (J_max ) were less affected in J. curcas. Both species displayed an efficient antioxidant mechanism by increasing activities of ascorbate peroxidase (APX) and superoxide dismutase (SOD). Overall, we suggest that the modulation of different photoprotective mechanisms is crucial to mitigate the effects caused by excess energy, maintaining photosynthetic apparatus efficiency and promoting the establishment of young plants of these two species under drought.

Incidence and antimicrobial resistance of enteropathogens isolated from an integrated aquaculture system

AIMS

To evaluate an integrated aquaculture system, microbiological analyses of water used in this system were carried out and the incidence and antimicrobial resistance of enteropathogens were determined in the related ecosystem.

METHODS AND RESULTS

Microbiological analysis was undertaken for Salmonella sp., Shigella sp., Vibrio sp. and Aeromonas sp. The disc-diffusion method was performed according to the Clinical and Laboratory Standards Institute. Water samples tested had 32.9% of faecal coliform rates (≤1600 per 100 ml) in accordance with WHO for pisciculture in wastewater. Salmonella spp. were detected in 14.5% of the samples. From a total of 33 strains, 15.1% were resistant to one or two antimicrobial drugs tested and multidrug resistance was not observed. Aeromonas spp. were identified in 91.6% of the samples. From a total of 416 strains, resistance to one antimicrobial class was observed in 66.3% and multidrug resistance in 37.7%.

CONCLUSIONS

This system reflects the community profile, drawing attention to the circulation of pathogens, because the genes coding for resistance to classical antibiotics and broad spectrum are a public health problem.

SIGNIFICANCE AND IMPACT OF THE STUDY

The reuse of water resources requires continuous monitoring as the system is subject to treatment failure, which can result in the spread of bacterial pathogens.

Functional groups of forest succession as dissipative structures: an applied study

This study tested the hypothesis that dissipative efficiency of tropical tree species could be an ecological advantage in the forest succession process. Daily leaf gas exchanges of a pioneer species (Guazuma ulmifolia) and a late successional species (Cariniana legalis) were evaluated under well-irrigated conditions and by withholding irrigation. Analyses of network connectance (Cg) and plant autonomy (At) were carried out in order to assess metabolic network changes in response to environmental perturbation. As a global estimation of latent heat dissipation, the capacity to both maintain and cool leaf temperature in response to air temperature changes (deltaT = T degrees Cair - T degrees Cleaf) was evaluated. The changes observed in both the systemic parameters (Cg and At) and the physiological ones brought about by water deficit, associated with discrepant growth rates between both species, suggested that the initial formation of gap canopies composed by pioneer species could simply be a result of the higher photosynthetic rates of these species, and not necessarily because late successional species cannot cope with such a heterogeneous environment as that of a gap. Our results indicate that, in the absence of water constraints, the highest CO2 assimilation rates of pioneer species are supported by the efficiency of the whole dissipative structure, involving both degradation and dissipative processes. As a practical result, our study suggests the deltaT analysis in order to evaluate the efficiency of dissipative structures and as a aid in characterizing functional groups.

Analysis of some factors involved in the virulence mechanism of Vibrio cholerae non-01

A study was carried out to evaluate the potential intestinal toxicity of 188 samples of Vibrio cholerae non-01 isolated from seawater found along the beaches of Rio de Janeiro city. Three different assays were carried out involving: (a) detection of vascular permeability factor (PF) in guinea pigs (together with assessment of two culture media for production of the toxin); (b) intestinal fluid accumulation (FA) in suckling mice; and (c) detection of haemolysin. The results demonstrated that both culture media gave a similar level of performance. In the animal assays, 43% of the samples induced PF in guinea pigs, 28.7% caused intestinal fluid accumulation in suckling mice, and 63.28% contained haemolysin. Only 4.25% of the samples gave positive results in all three tests.

Evaluation of virulence factors in environmental isolates of Vibrio species

Strains of Vibrio parahaemolyticus, Vibrio fluvialis and Vibrio mimicus isolated from seafood and seawater were examined for characteristics related to infectivity, such as enzymatic activity and animal assays. All strains hydrolysed DNA, starch, gelatin and chitin. Variable results were obtained with the haemolysin, chondroitin, collagen, elastin and lecithin tests. Production of thermostable direct haemolysin by V. parahaemolyticus was detected in 7.1% strains derived from seafood and 2% from seawater. In the animal assays, strains of V. fluvialis showed positive results at skin PF (75%), mouse lethality (100%), but no fluid accumulation in the suckling mice model was noted. Concerning V. mimicus, results showed skin PF (100%), mouse lethality (100%) and fluid accumulation in suckling mice (66.6%).

Analysis of some virulence factors of Vibrio vulnificus isolated from Rio de Janeiro, Brazil

Twenty strains of V. vulnificus isolated from the environment were investigated for characteristics related to their infectivity such as colonial morphology, enzymatic activity and animal assays. The presence of DNase, chitinase, amylase, lecithinase and gelatinase was observed in 100% of the strains, haemolytic activity was absent, and variable results were obtained in elastase, collagenase and chondroitinase. In the animal assays, 70% of the strains were lethal to adult mice, while 45% caused fluid accumulation in suckling mice. Although all strains had opaque colonies, only 3 of the 20 had the three enzymes elastase, collagenase and gelatinase, and only one of these was virulent in animal assays.