Dietary assimilation and the digestive strategy of the omnivorous anomuran land crab Birgus latro (Coenobitidae).

On Christmas Island, Indian Ocean, the diet of robber crabs, Birgus latro (Linnaeus) was generally high in fat, storage polysaccharides or protein and largely comprised fruits, seeds, nuts and animal material. The plant items also contained significant amounts of hemicellulose and cellulose. In laboratory feeding trials, crabs had similar intakes of dry matter when fed artificial diets high in either fat or storage polysaccharide, but intake was lower on a high protein diet. Assimilation coefficients of dry matter (69–74%), carbon (72–81%), nitrogen (76–100%), lipid (71–96%) and storage polysaccharide (89–99%) were high on all three diets. B. latro also assimilated significant amounts of the chitin ingested in the high protein diet ( 93%) and hemicellulose (49.6–65%) and cellulose (16–53%) from the high carbohydrate and high fat diets. This is consistent with the presence of chitinase, hemicellulase and cellulase enzymes in the digestive tract of B. latro. The mean retention time (27.2 h) for a dietary particle marker (⁵⁷Co-labelled microspheres) was longer than measured in leaf-eating land crabs. The feeding strategy of B. latro involves the selection of highly digestible and nutrient-rich plant and animal material and retention of the digesta for a period long enough to allow extensive exploitation of storage carbohydrates, lipids, protein and significant amounts of structural carbohydrates (hemicellulose, cellulose and chitin).

Exercise in the fasted state facilitates fibre type-specific intramyocellular lipid breakdown and stimulates glycogen resynthesis in humans

The effects were compared of exercise in the fasted state and exercise with a high rate of carbohydrate intake on intramyocellular triglyceride (IMTG) and glycogen content of human muscle. Using a randomized crossover study design, nine young healthy volunteers participated in two experimental sessions with an interval of 3 weeks. In each session subjects performed 2 h of constant-load bicycle exercise (∼75% V_O2max ), followed by 4 h of controlled recovery. On one occasion they exercised after an overnight fast (F), and on the other (CHO) they received carbohydrates before (∼150 g) and during (1 g (kg bw)⁻¹ h⁻¹) exercise. In both conditions, subjects ingested 5 g carbohydrates per kg body weight during recovery. Fibre type-specific relative IMTG content was determined by Oil red O staining in needle biopsies from m. vastus lateralis before, immediately after and 4 h after exercise. During F but not during CHO, the exercise bout decreased IMTG content in type I fibres from 18 ± 2% to 6 ± 2% (P= 0.007) area lipid staining. Conversely, during recovery, IMTG in type I fibres decreased from 15 ± 2% to 10 ± 2% in CHO, but did not change in F. Neither exercise nor recovery changed IMTG in type IIa fibres in any experimental condition. Exercise-induced net glycogen breakdown was similar in F and CHO. However, compared with CHO (11.0 ± 7.8 mmol kg⁻¹ h⁻¹), mean rate of postexercise muscle glycogen resynthesis was 3-fold greater in F (32.9 ± 2.7 mmol kg−1 h−1, P= 0.01). Furthermore, oral glucose loading during recovery increased plasma insulin markedly more in F (+46.80 μU ml⁻¹) than in CHO (+14.63 μU ml⁻¹, P= 0.02). We conclude that IMTG breakdown during prolonged submaximal exercise in the fasted state takes place predominantly in type I fibres and that this breakdown is prevented in the CHO-fed state. Furthermore, facilitated glucose-induced insulin secretion may contribute to enhanced muscle glycogen resynthesis following exercise in the fasted state.

Growth and product quality of European eel (Anguilla anguilla) as affected by dietary protein and lipid sources

A 12-week feeding trial was undertaken to evaluate the effects of partial replacement of marine raw materials in the diet with soybean meal and beef tallow on growth and product quality of European eel (Anguilla anguilla ). Based on growth, feed efficiency and chemical composition, soybean meal was found to be an unsuitable ingredient for eel diets as a substitute for fishmeal (25% on a protein basis), probably because of the low digestibility of its carbohydrate content. However, beef tallow can be used to replace 50% of fish oil without reduction in growth, provided that digestible carbohydrates are present in the diet. No major effects of protein and lipid sources in the diet were found on fillet chemical composition. Sensory analysis revealed no significant differences between fish fed the control and the experimental diets, with the exception of salty taste which was significantly higher in fish fed combined soybean meal and beef tallow compared with fish fed the control diet.

Chemical characterisation of the oligosaccharides in hooded seal (Cystophora cristata) and Australian fur seal (Arctocephalus pusillus doriferus) milk

Carbohydrates were extracted from hooded seal milk, Crystophora cristata (family Phocidae). Free oligosaccharides were separated by gel filtration and then purified by ion exchange chromatography, gel filtration and preparative thin layer or paper chromatography and their structures determined by ¹H-NMR. The hooded seal milk was found to contain inositol and at least nine oligosaccharides, most of which had lacto-N-neotetraose or lacto-N-neohexaose as core units, similar to those in milk of other species of Carnivora such as bears (Ursidae). Their structures were as follows: Gal(β1-4)Glc (lactose); Fuc(α1-2)Gal(β1-4)Glc (2′-fucosyllactose); Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (lacto-N-neotetraose); Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (lacto-N-fucopentaose IV); Gal(β1-4)GlcNAc(β1-3)[Gal(β1-4)GlcNAc(β1-6)]Gal(1-4)Glc (lacto-N-neohexaose); Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)[Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (monofucosyl lacto-N-neohexaose a); Gal(β1-4)GlcNAc(β1-3)[Fuc(α1-2)Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (monofucosyl lacto-N-neohexaose b); Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)[Fuc(α1-2)Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (difucosyl lacto-N-neohexaose); Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (para lacto-N-neohexaose); Fuc(α1-2)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (monofucosyl para lacto-N-neohexaose). Milk of the Australian fur seal, Arctophalus pusillus doriferus (family Otariidae) contained inositol but no lactose or free oligosaccharides. These results, therefore, support the hypothesis that the milk of otariids, unlike that of phocids, contains no free reducing saccharides.

Minimising colonic fermentation of high fructan foods : using food processing techniques to reduce levels of fructans in onion and garlic

Background: Irritable Bowel Syndrome (IBS) is a chronic functional disorder of the bowel, affecting up to 15% of Australian adults. Dietary triggers need to be identified and controlled. Researchers have shown that short chain carbohydrates, fructans (high in onion and garlic) play a major role in triggering IBS symptoms. Current dietary management aims to limit the intake of fructans in the diet. Another approach may be to use simple food processing to reduce fructans in foods.

Objective: To investigate if pickling will reduce fructan levels in garlic and shallots, and if pickled garlic and shallots reduce colonic fermentation, and  abdominal symptoms in human volunteers.

Design: Fructan levels of the garlic and shallots were measured using the Megazyme fructan assay. 18 volunteers (13 healthy and 5 IBS) participated in a single blinded, randomised cross over study. Subjects were randomly assigned to receive a breakfast (potato and salmon patty) that was either high (unprocessed) or low (processed/pickled) in garlic and shallots. Breath hydrogen was measured every hour over a ten hour period, and abdominal symptoms were assessed using validated questionnaires.

Outcomes: Pickling over a 12 day period significantly reduced fructan levels in both garlic (p=.0.00) and shallots (p=0.00). Consumption of the low fructan breakfast resulted in significantly lower breath hydrogen (p=0.05), abdominal pain (p=0.032), and wind (p=0.04).

Conclusion: Pickling results in significantly lowered fructan levels in problem foods- shallots and garlic, and lowered colonic fermentation and abdominal symptoms in both healthy and IBS volunteers. This study provides another dietary strategy for dietetic counselling of patients with IBS.

Amylase and glucosidase enzyme inhibitory activity of ginger (Zingiber officinale Roscoe) an in vitro study

The prevalence of type 2 diabetes has reached to an epidemic proportion in Sri Lanka. The need for achieving better control of blood glucose level has been evident in diabetes management. However it is not easy to achieve this goal in a large proportion of patients. This is partly due to limitations of currently available pharmacological agents which stimulate research on novel anti-diabetic agents with different mechanisms. Digestive enzymes have been targeted as potential avenues for modulation of blood glucose concentration through inhibition of the enzymatic breakdown of complex carbohydrates to meal derived glucose absorption. Acarbose is a widely used oral anti-diabetic drug which inhibits the α-glucosidase, enzyme responsible for breaking down of disaccharides and polysaccharides into glucose. Many herbal extracts have been found to posses similar inhibitory effects. Ginger (Zingiber officinale Roscoe) has developed a reputation in treatment of several diseases. In vitro enzymic inhibitory effect of ginger was investigated in this study. Enzymes α -amylase and α -glucosidase treated with either Acarbose or ginger extract were allowed to react with cooked rice and percentages of glucose content were measured. The glucosidase and amylase activities on the rice were inhibited by addition of ginger cause significant reduction in glucose percentages (36.86± 1.05 to 26.87± 2.17, P<0.05 and 49.04±0.65 to 35.35±2.22, P<0.05) which showed comparable results with Acarbose on glucosidase activity (36.86± 1.05 to, 27.8±1.32 P<0.05). Results of the study indicates ginger as a potential plant based amylase and glucosidase inhibitor in carbohydrate digestion but usage in glycaemic control in human has to be investigated further.

Glycemic index and glycogen

INTRODUCTION : Fatigue in sports is often associated with depletion of muscle glycogen storage. Obesity is considered to be a major barrier against physical activity in sports. In order to bring the glycogen storage to a satisfactory level sports persons tend to increase consumption carbohydrates, preferred consumption of high glycemic index (HGI) than low glycemic index (LGI) diets. But HGI foods may promote postprandial carbohydrate oxidation at the expense of fat oxidation and increase body fat gain. LGI diets that produce a low and slow glycemic response may enhance higher glycogen storage instead of fat deposition.

METHODOLOGY : To test this hypothesis, 30 male Wistar rats after weaning were given either a high glycemic index (HGI) or low glycemic index (LGI) diet for until their age of 12 weeks. Then the subjects were scarified and their plasma, serum, and muscle samples were collected. RESULTS-The study revealed that HGI diets fed rats had higher plasma cholesterol and Leptin (LGI Leptin 1.34 +/- 0.13ng/ml, HGI Leptin 2.12 +/- .20ng/ml) concentrations. It also found the liver and muscle glycogen storage in LGI diets showed higher level (LGI-liver 108 +/-3.0 mg/100g, LGI-muscle 22.6+/- 2.3g/100g) than that of HGI (HGI-liver 96 +/- 2.0mg/100g, HGI-muscle 18+/- 1.5g/100g) diets.

CONCLUSION : the long term feeding of LGI carbohydrate encourages more glycogen storage while HGI increases fat deposition. Consumption of LGI diets has an advantage over HGI diets of higher physical activity while elevating glycogen storage and reducing chances of obesity.

Interaction of dietary fibre, carbohydrate metabolism and diabetes in the rat

It is currently accepted that the most appropriate diet in the treatment of non-insulin-dependent diabetes mellitus "e;NIDDM"e; is high in carbohydrates, high in fibre and low in fat. Dietary fibre reduces the rate of carbohydrate absorption, which may have a beneficial effect on insulin action. Furthermore, high fibre diets also increase the amount of carbohydrates which are not absorbed from the small intestine. These malabsorbed carbohydrates are fermented by the bacterial population in the large intestine, producing short chain fatty acids "e;SCFA"e;, including propionate, which has been shown to alter liver carbohydrate metabolism. This thesis investigated the actions of slowed carbohydrate absorption and carbohydrate malabsorption in streptozotocin-induced "e;STZ"e; diabetic rats. High carbohydrate diet supplemented with guar gum, a soluble dietary fibre, fed to STZ diabetic rats improved insulin sensitivity. investigation of the alterations in the stomach and small intestine demonstrated that guar increased the viscosity of the meal in the intestine. The action of increased fermentation, producing more propionate, was investigated by supplementing propionate into the diets of STZ diabetic rats or when perfused into isolated rat livers. No changes in insulin action or liver glucose metabolism were measured. in addition, it was shown that guar gum reduces food intake in STZ diabetic rats. Mild reductions in food intake in STZ diabetic rats were shown to increase insulin action. In summary, STZ diabetic rats fed high carbohydrate, high fibre diets reductions in food consumption and slowed carbohydrate absorption are important factors which may lower blood glucose concentrations and increase insulin action. increased SCFA production is unlikely to contribute significantly to the improvements in insulin action.

Adrenergic regulation of carbohydrate metabolism during exercise

1. This series of studies was undertaken to examine the adrenergic regulation of carbohydrate metabolism during exercise. Recreationally active males were tested during moderate to intense exercise on a stationary cycle ergometer. Venous and arterial plasma obtained from indwelling catheters was analysed for hormonal and metabolite responses, and hepatic glucose production and glucose uptake were measured using the tracer-dilution method with stable isotopes. Muscle samples were obtained by the needle biopsy technique to examine muscle glycogen utilisation and the flux of related muscle metabolites using enzymatic, fluorometric and radioisotopic techniques. 2. During moderate exercise adrenaline infusion induced a marked hyperglycemia and this was due to reduced glucose uptake rather than enhanced hepatic glucose production. The reduction in glucose uptake was most likely mediated by a decrease in glucose phosphorylation, as indicated by the accumulation of glucose 6-phosphate with adrenaline infusion. 3. The hyperglycemic response to intense exercise was prevented by the administration of α- and β-adrenergic antagonists. Adrenergic blockade was without effect on hepatic glucose production whereas glucose uptake was enhanced when compared with control subjects. These data support the notion that adrenergic mechanisms are more important in restraining glucose uptake than enhancing hepatic glucose production during intense exercise. Other glucoregulatory factors are responsible for the increase in glucose production during intense exercise. 4. Elevated plasma adrenaline levels during moderate exercise in untrained men increases skeletal muscle glycogen breakdown and PDH activation which results

Skeletal muscle GLUT-4 gene and protein regulation

Twenty two, young, healthy individuals participated in three studies aiming to assess the effect of various types of physical activity - acute exercise of moderate intensity and duration, varying intensity, short-term training - on skeletal muscle GLUT-4 gene and protein expression as well as on a range of genes encoding the proteins involved in carbohydrate metabolism in skeletal muscle.

Body build : its influence on anthropometric measurements, fat distribution, body composition and carbohydrate metabolism

Examines the interrelationships between body build and body composition and carbohydrate and lipid metabolism in healthy young men and women. Results indicate that in women a low relative sitting height may be an early marker of susceptibility to abdominal obesity and its consequences, non insulin dependent diabetes and coronary heart disease.

Carbon nanotubes for biological and biomedical applications

Ever since the discovery of carbon nanotubes, researchers have been exploring their potential in biological and biomedical applications. The recent expansion and availability of chemical modification and bio-functionalization methods have made it possible to generate a new class of bioactive carbon nanotubes which are conjugated with proteins, carbohydrates, or nucleic acids. The modification of a carbon nanotube on a molecular level using biological molecules is essentially an example of the 'bottom-up' fabrication principle of bionanotechnology. The availability of these biomodified carbon nanotube constructs opens up an entire new and exciting research direction in the field of chemical biology, finally aiming to target and to alter the cell's behaviour at the subcellular or molecular level. This review covers the latest advances of bio-functionalized carbon nanotubes with an emphasis on the development of functional biological nano-interfaces. Topics that are discussed herewith include methods for biomodification of carbon nanotubes, the development of hybrid systems of carbon nanotubes and biomolecules for bioelectronics, and carbon nanotubes as transporters for a specific delivery of peptides and/or genetic material to cells. All of these current research topics aim at translating these biotechnology modified nanotubes into potential novel therapeutic approaches.

Characteristics of energy under-reporting in children and adolescents

Under-reporting (UR) of food intake is an issue of concern, as it may distort the relationships studied between diet and health. This topic has been scarcely addressed in children. The objective of the study was to assess the extent of UR in French children and investigate associated covariates. A total of 1455 children aged 3–17 years were taken from the nationally representative cross-sectional French étude Individuelle Nationale des Consommations Alimentaires (INCA2) dietary survey (2006–7). Food intake was reported in a 7 d diet record. Socio-economic status, sedentary behaviour, weight perception variables and food habits were collected by questionnaires. Weight and height were measured. Under-reporters were identified according to the Goldberg criterion adapted to children. Multivariate logistic regressions investigated the associations between UR and covariates. Rates of under-reporters were 4·9 and 26·0 % in children aged 3–10 and 11–17 years, respectively (P < 0·0001), without significant differences between boys and girls. Overall, UR was positively associated with a lower socio-economic status, overweight, skipping breakfast and dinner, a higher contribution of proteins to energy intake (EI), and a lower contribution of simple carbohydrates to EI. Under-reporters aged 3–10 years also had a higher sedentary behaviour and a lower snack-eating frequency. In adolescents, UR was also associated with a less-frequent school canteen attendance, a perception of being overweight, a wish to weigh less, and current and past restrictive diets. In conclusion, under-reporters differ from plausible reporters in several characteristics related to diet, lifestyle, weight status and socio-economic status. Therefore, it is important to consider this differential UR bias when investigating diet–disease associations in children.

Splash!: a prospective birth cohort study of the impact of environmental, social and family-level influences on child oral health and obesity related risk factors and outcomes

Background: Dental caries (decay) is the most prevalent disease of childhood. It is often left untreated and can impact negatively on general health, and physical, developmental, social and learning outcomes. Similar to other health issues, the greatest burden of dental caries is seen in those of low socio-economic position. In addition, a number of diet-related risk factors for dental caries are shared risk factors for the development of childhood obesity. These include high and frequent consumption of refined carbohydrates (predominately sugars), and soft drinks and other sweetened beverages, and low intake of (fluoridated) water. The prevalence of childhood obesity is also at a concerning level in most countries and there is an opportunity to determine interventions for addressing both of these largely preventable conditions through sustainable and equitable solutions. This study aims to prospectively examine the impact of drink choices on child obesity risk and oral health status.
Methods/Design: This is a two-stage study using a mixed methods research approach. The first stage involves qualitative interviews of a sub-sample of recruited parents to develop an understanding of the processes involved in drink choice, and inform the development of the Discrete Choice Experiment analysis and the measurement instruments to be used in the second stage. The second stage involves the establishment of a prospective birth cohort of 500 children from disadvantaged communities in rural and regional Victoria, Australia (with and without water fluoridation). This longitudinal design allows measurement of changes in the child’s diet over time, exposure to fluoride sources including water, dental caries progression, and the risk of childhood obesity.
Discussion: This research will provide a unique contribution to integrated health, education and social policy and program directions, by providing clearer policy relevant evidence on strategies to counter social and environmental factors which predispose infants and children to poor health, wellbeing and social outcomes; and evidence-based strategies to promote health and prevent disease through the adoption of healthier lifestyles and diet. Further, given the absence of evidence on the processes and effectiveness of contemporary policy implementation, such as community water fluoridation in rural and regional communities it’s approach and findings will be extremely
informative.

Carbohydrate intake strategies to enhance endurance exercise performance

While elite Olympic distance triathletes consume adequate carbohydrate pre-competition, many fail to meet suggested guidelines during actual competition. Furthermore, metabolic adaptations that occur in response to training appear similar under varying conditions of carbohydrate availability. However, daily training with high carbohydrate availability increases the use of carbohydrate consumed during exercise.