Any intervention which causes negative energy balance is guaranteed to be efficacious in producing weight loss, which will continue while there is negative energy balance or be maintained as long as the new energy balance is maintained. In clinical practice compliance is rarely 100% so the efficiency of even the most efficacious treatment is usually low. However, recent evidence-based guidelines have recognized the clinical benefits of moderate (5-10%) weight loss, which is achievable using a variety of interventions. Long-term studies of 'weight loss' are, in reality, combinations of weight loss (usually completed in 1-6 months) followed by variable weight maintenance, set in the context of progressive adult weight gain in an obesogenic environment. Few studies have adopted specific and separate strategies for weight loss and weight maintenance. Meta-analyses conducted by non-expert methodologists have failed to recognize these distinctions, and have criticized the available research without understanding the different needs of studies with weight change as the outcome variable, which require randomized controlled trials (RCT), and those with weight loss as the treatment, intended to improve metabolic or biomedical outcome measures. An RCT design is inapplicable to studies of biomedical end points (e.g. cardiac risk factors) when weight loss is the treatment. Because fixed weight loss cannot be prescribed there is always a range of weight changes in any study, and single-sample studies with regression analysis provide the best design. An RCT study design does not give useful information about clinical value as the control group is always 'treated' to some extent. Placebo- (or control)-subtracted differences are misleading because in an RCT all subjects recruited to active treatment, including non-responders, are continued on treatment for the full duration of the study. In routine clinical practice, treatments are changed in the light of early experience as a therapeutic trial to optimize the results for each individual, and audit is required to evaluate 'long term weight loss'.
We studied the associations of a difference in linoleic acid or carbohydrate intake with plasma cholesterol levels and risk of CHD in a prospective cohort study in the Netherlands. Data on diet (FFQ) and plasma total and HDL-cholesterol were available at baseline (1993-7) of 20,069 men and women, aged 20-65 years, who were initially free of CVD. Incidence of CHD was assessed through linkage with mortality and morbidity registers. During an average of 10 years of follow-up, 280 CHD events occurred. The intake of linoleic acid ranged from 3·6 to 8·0 % of energy (en%), whereas carbohydrate intake ranged from 47·6 to 42·5 en% across quintiles of linoleic acid intake. Linoleic acid intake was inversely associated with total cholesterol and HDL-cholesterol in women but not in men. Linoleic acid intake was not associated with the ratio of total to HDL-cholesterol. No association was observed between linoleic acid intake and CHD incidence, with hazard ratios varying between 0·83 and 1·00 (all P>0·05) compared to the bottom quintile. We conclude that a 4-5 en% difference in linoleic acid or carbohydrate intake did not translate into either a different ratio of total to HDL-cholesterol or a different CHD incidence.
The ability of probiotics to improve bowel habits or transit time has been shown in healthy populations. Additional data are required to support the use of specific probiotics to improve gastrointestinal (GI) well-being. The present study was designed to investigate the effect of consuming fermented milk (FM) on GI well-being, digestive symptoms and health-related quality of life (HRQoL) amongst women without diagnosed GI disorders. In this double-blind, controlled, parallel-design study, subjects were randomised to ingest daily either 2 x 125 g FM containing Bifidobacterium lactis DN-173 010 and yoghurt strains or a control non-fermented dairy product for 4 weeks followed by a 4-week wash-out period. GI well-being and digestive symptoms were assessed weekly. HRQoL was measured every 4 weeks. Data were analysed using analysis of covariance and logistic regression, correcting for baseline values on the full analysis set population of 197 women (aged 18-60 years). The percentage of women reporting an improvement in their GI well-being was significantly (P < 0.01) higher in the FM group v. the control group (OR 1.69; 95 % CI 1.17, 2.45). A significantly (P < 0.05) more pronounced decrease in the composite score of digestive symptoms was observed in the FM group when comparing with the control group (least squares mean - 0.57; 95 % CI - 1.12, - 0.02). Among HRQoL dimensions, the digestive comfort score was significantly (P < 0.05) improved in the FM group compared with the control group. The present study showed that the daily consumption of a specific FM is able to improve GI well-being and digestive symptoms in adult women without GI disorders.
The objective was to study the multidimensional nature of the relationship between adult obesity (OB) and socio-economic status (SES), using comprehensive indices of SES taken separately or synthesised in an overall index. A nationally representative sample of adults aged 18-79 years was taken from the French second National Individual Survey on Food Consumption (INCA 2) dietary survey (2006-07). Weight and height were measured and OB defined as BMI ≥ 30 kg/m2. SES variables were reported in questionnaires and included occupation, education and characteristics of household wealth. Composite indices of SES (household wealth and overall SES indices) were computed by correspondence analysis, and relationships with OB were investigated with logistic regression analysis. In total, 11·8 (95 % CI 10·1, 13·4) % of French adults were obese, without significant difference by sex. While no significant relationship was observed in men, all SES indicators were inversely correlated to OB in women. Both education and the household wealth index were retained in the stepwise multivariate model, confirming that different socio-economic variables are not necessarily proxies of each other regarding the OB issue. On the other hand, 'controlling for SES' while including several measures of SES in multivariate models may lead to collinearity, and thus over-adjustment. A more integrative approach may be to derive a synthetic index by including the SES factors available in a given study. Beyond this methodological perspective, understanding how OB is related to the different dimensions of SES should help to target the more vulnerable groups and increase the effectiveness of prevention.
Regular nut consumption is associated with reduced CVD risk. Insight into nut consumption patterns provides important information to help design strategies to encourage intake. The present study aimed to describe nut consumption in terms of the percentage of consumers, mean grams eaten among the population and nut consumers, and to identify the predictors of nut consumption. Data from the 24 h dietary recalls of the 2008/09 New Zealand Adult Nutrition Survey (n 4721) were used to measure nut consumption. On the recall day, the percentages of consumers of whole nuts, nut butters and nuts from hidden sources were 6·9 % (n 240), 7·2 % (n 346) and 19·2 % (n 732), respectively (28·9 % (n 1167) combined (total)). The mean grams consumed by the population were relatively low for whole nuts (2·8 g/d), nut butters (0·9 g/d), nuts from hidden sources (1·5 g/d) and total nuts (5·2 g/d). Among consumers, the mean daily grams of whole nuts, nut butters, nuts from hidden sources and total nuts eaten were 40·3, 12·9, 7·8 and 17·9 g/d, respectively. Those aged 15-18 years had the lowest whole nut consumption, but had the highest nut butter consumption. The consumption of total nuts was positively associated with education and socio-economic status, while whole nut consumption was inversely associated with BMI. In conclusion, the low percentage of nut consumers is of concern and new strategies to increase nut consumption are required. Future public health initiatives should be mindful of these patterns and predictors. In particular, different forms of nuts may appeal to different age and socio-economic groups.
Diet-induced changes in the activities of bacterial enzymes are known to play a role in colon cancer development. Resveratrol has been implicated as a protective agent in carcinogenesis. In the present study, the effect of resveratrol on the activities of faecal and colonic biotransforming enzymes such as beta-glucuronidase, beta-glucosidase, beta-galactosidase, mucinase, nitroreductase and faecal sulfatase activity was assessed. The total number of aberrant crypt foci and their distribution in the proximal, medial and distal colon were observed in 1,2-dimethylhydrazine (DMH)-induced rats (group 3) and other treatment groups (groups 4-6). DMH (0.02 g/kg body weight) was given subcutaneously once a week for 15 consecutive weeks, and the experiment was terminated at 30 weeks. DMH-treated rats showed elevated levels of cancer-associated bacterial enzyme activities, whereas on resveratrol supplementation in three different regimens, rats showed lowered activities. Resveratrol supplementation throughout the experimental period (group 6) exerted a more pronounced effect (P < 0.01) by modulating the development of aberrant crypt foci and the activities of bacterial enzymes than did the other treatment regimens (groups 4 and 5). Thus, the present results demonstrate the inhibitory effect of resveratrol on DMH-induced colon carcinogenesis in rats.
One of the objectives of the present study was to investigate whether 1 % conjugated linoleic acid (CLA) in the diet reduced tumour incidence in the colon of 1,2-dimethylhydrazine (DMH)-treated rats. Colon cancer was induced by injecting 6-week-old, male, Sprague-Dawley rats with 15 mg/kg DMH twice per week for 6 weeks. They were fed either 1 % CLA or a control diet ad libitum for 30 weeks. Dietary CLA significantly decreased colon tumour incidence (P<0.05). Our second objective was to investigate whether apoptosis in the colon mucosa of DMH-treated rats was affected by the amount of dietary CLA and whether the changes in apoptosis were related to those in fatty acid-responsive biomarkers. For this purpose, rats were killed after being fed a diet containing 0 %, 0.5 %, 1 % or 1.5 % CLA for 14 weeks. CLA was undetected in the mucosa of rats fed the 0 % CLA diet and increased to 5.9 mg/g phospholipid in rats fed the 0.5 % diet. The apoptotic index estimated by the terminal deoxynucleotidyl transferase-mediated dUTP nick and labelling technique was increased by 251 % and the 1,2-diacylglycerol content was decreased by 57 % in rats fed 0.5 % CLA. No further changes in these variables were observed when CLA in the diet was raised to 1.0 % or 1.5 %. However, dietary CLA decreased mucosal levels of prostaglandin E2, thromboxane B2 and arachidonic acid in a dose-dependent manner. The present data indicate that dietary CLA can inhibit DMH-induced colon carcinogenesis by mechanisms probably involving increased apoptosis.
1. The main products of fermentation of 1,2-propanediol were n -propanol and propionic acid, but variable amounts of acetic acid and carbon dioxide were also formed. The concentrations of an intermediate propionaldehyde increased and then decreased.
2. A tentative scheme is suggested, showing that 1,2-propanediol is first dehydrated to propionaldehyde, which is then reduced to n -propanol. The scheme also explains the formation of propionic and acetic acids and shows how the metabolism of 1,2-propanediol is related to that of rhamnose.
3. Experiments with samples of rumen contents from animals on various diets showed that 1,2-propanediol was metabolized most rapidly when the animals were given molassed sugar-beet pulp. The rates of dissimilation of the diol increased with the concentration of rumen contents and with the concentration of substrate.
4. The dissimilation of 1,2-propanediol by rumen micro-organisms resulted in an increased uptake of hydrogen. The metabolic hydrogen, arising from the inhibition of methane production by chloroform, appeared to be better utilized than the gaseous hydrogen.
5. Oxygen gas did not affect the utilization of 1,2-propanediol, but the diol increased the uptake of oxygen by the rumen contents. The hydrogen and carbon balances were better when 1,2-propanediol was incubated anaerobically than in the presence of oxygen.
Propionibacterium freudenreichii, a food-grade bacterium able to kill colon cancer cell lines in vitro by apoptosis, may exert an anticarcinogenic effect in vivo. To assess this hypothesis, we administered daily 2 x 10(10) colony-forming units (CFU) of P. freudenreichii TL133 to human microbiota-associated (HMA) rats for 18 d. Either saline or 1,2-dimethylhydrazine (DMH) was also administered on days 13 and 17 and rats were killed on day 19. The levels of apoptosis and proliferation in the mid and distal colon were assessed by terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) immunolabelling, respectively. The administration of P. freudenreichii TL133 significantly increased the number of apoptotic cells in DMH-treated rats compared to those given DMH only (P < 0.01). Furthermore, propionibacteria were able to decrease the proliferation index in the distal colon after treatment with DMH (P < 0.01). Conversely, propionibacteria alone did not exert such an effect on healthy colonic mucosa. P. freudenreichii TL133 thus facilitated the elimination of damaged cells by apoptosis in the rat colon after genotoxic insult and may play a protective role against colon cancer.
Aliphatic dioic acids have been proposed as alternative nutrients in selected clinical situations. In this study, their possible insulinotropic action was investigated in isolated rat pancreatic islets prepared from fed rats. Azelaic acid, sebacic acid and tridecanedioic acids, when tested at a 10.0 mm concentration, were found to augment insulin release evoked by D-glucose (7.0 mm) in the pancreatic islets. Likewise, glycerol-1,2,3-tris(dodecanoedioate), when used at concentrations close to 1.0 mm, increased the secretory response to the hexose. It is speculated that these findings may extend to insulin-producing cells, the knowledge that aliphatic dioic acids or their esters may act as energy substrates, e.g. in parenteral nutrition.
Multiple pathways including oxidative stress and mitochondrial damage are implicated in neurodegeneration during Parkinson's disease (PD). The current PD drugs provide only symptomatic relief and have limitations in terms of adverse effects and inability to prevent neurodegeneration. Therefore, there is a demand for novel compound(s)/products that could target multiple pathways and protect the dying midbrain dopaminergic neurons, with potential utility as adjunctive therapy along with conventional drugs. Turmeric is a spice used in traditional Indian cuisine and medicine with antioxidant, anti-inflammatory and potential neuroprotective properties. To explore the neuroprotective property of turmeric in PD, mice were subjected to dietary supplementation with aqueous suspensions of turmeric for 3 months, mimicking its chronic consumption and challenged in vivo with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Brain samples from untreated and treated groups were characterised based on mitochondrial complex I (CI) activity, protein nitration and tyrosine hydroxylase immunoreactivity. Chronic turmeric supplementation induced the enzyme activity of γ-glutamyl cysteine ligase, which in turn increased glutathione levels and protected against peroxynitrite-mediated inhibition of brain CI. These mice were also protected against MPTP-mediated protein nitration, CI inhibition and degeneration of substantia nigra neurons in the brain. We conclude that chronic dietary consumption of turmeric protects the brain against neurotoxic insults, with potential application in neurodegeneration. Further characterisation of the active constituents of turmeric that potentially promote neuroprotection could improve the utility of dietary turmeric in brain function and disease.
Three experiments were carried out to investigate the effects of supplemental dietary 1,25-dihydroxycholecalciferol (1,25(OH)2cholecalciferol) and a low dietary Ca:P ratio on the occurrence of tibial dyschondroplasia (TD) in 3-week-old broilers. Histopathology was used to diagnose TD. In the first experiment, feeding a diet containing 7.5 g Ca and 7.6 g P/kg gave a higher incidence of TD than a control diet containing normal amounts of Ca and P (12 and 6 g/kg respectively). Increasing the dietary supplement of cholecalciferol in the imbalanced diet prevented rickets but did not decrease the incidence of TD. In the second experiment, supplementing the imbalanced diet with 10 micrograms 1,25(OH)2cholecalciferol/kg prevented TD completely but also gave a slight growth depression. In the third experiment the imbalanced diet was supplemented with 0, 2.5, 5 or 10 micrograms 1,25(OH)2 cholecalciferol/kg. The supplement of 2.5 micrograms/kg depressed and the higher supplements prevented the occurrence of TD, this time without a growth depression. Feeding the 10 micrograms/kg supplement for the first week only did not prevent TD. Plasma total Ca, inorganic P and alkaline phosphatase (EC 184.108.40.206) were unaffected by diet but 1,25(OH)2cholecalciferol was higher on the imbalanced than on the control diet. Supplementation of the imbalanced diet with 1,25(OH)2cholecalciferol did not increase plasma levels. It is concluded that 1,25(OH)2cholecalciferol is exerting a powerful biological effect in this model of TD, but the mechanism is unclear.
Hypovitaminosis D may be associated with diabetes, hypertension and CHD. However, because studies examining the associations of all three chronic conditions with circulating 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) are limited, we examined these associations in the US Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial (n 2465). Caucasian PLCO participants selected as controls in previous nested case-control studies of 25(OH)D and 1,25(OH)(2)D were included in this analysis. Diabetes, CHD and hypertension prevalence, risk factors for these conditions and intake of vitamin D and Ca were collected from a baseline questionnaire. Results indicated that serum levels of 25(OH)D were low (< 50 nmol/l) in 29 % and very low (< 37 nmol/l) in 11 % of subjects. The prevalence of diabetes, hypertension and CHD was 7, 30 and 10 %, respectively. After adjustment for confounding by sex, geographical location, educational level, smoking history, BMI, physical activity, total dietary energy and vitamin D and Ca intake, only diabetes was significantly associated with lower 25(OH)D and 1,25(OH)(2)D levels. Caucasians who had 25(OH)D ≥ 80 nmol/l were half as likely to have diabetes (OR 0·5 (95 % CI 0·3, 0·9)) compared with those who had 25(OH)D < 37 nmol/l. Those in the highest quartile of 1,25(OH)(2)D (≥ 103 pmol/l) were less than half as likely to have diabetes (OR 0·3 (95 % CI 0·1, 0·7)) than those in the lowest quartile (< 72 pmol/l). In conclusion, the independent associations of 25(OH)D and 1,25(OH)(2)D with diabetes prevalence in a large population are new findings, and thus warrant confirmation in larger, prospective studies.
1. The effects of vitamin D 3 (D 3 ) on serum levels of 1, 25-dihydroxyvitamin D 3 (1, 25(OH) 2 D 3 ), ionic calcium, total Ca and phosphorus in chicks were studied from the time of hatching until sexual maturity.
2. Chicks fed on a diet low in D 3 showed a serum level of 1, 25(OH) 2 D 3 higher than that in chicks on a normal-D 3 diet, for both sexes and at any given age.
3. A dramatic increase in the serum level of 1, 25(OH) 2 D 3 occurred in female birds approaching sexual maturity and in laying hens raised on the low-D 3 diet the level was five times that of their counterparts raised on a normal-D 3 diet.
4. Theserum 1, 25(OH) 2 D 3 levelin adultmalesin thelow-D 3 groups wasseven timesthatofthoseon thenormal-D 3 diet.
5. The serum level of 25-hydroxyvitamin D 3 remained relatively unchanged at weeks 2 and 15 in birds on a low D 3 intake as well as in those fed on a normal-D 3 diet. Nevertheless, the levels of 25-hydroxyvitamin D 3 were different between the two groups.
6. No significant change was observed in the level of ionized serum Ca in relation to dietary regimen, but there was an increase in total Ca concentration in females with the onset of reproduction.
7. The serum P level decreased gradually with age, reaching a minimum value 3 and 8 weeks before laying commenced in the groups on low- and normal-D 3 diets respectively. An increase was observed when the hens began laying.
8. Chicks adapted to a low-D 3 diet by elevation of their plasma level of 1, 25(OH) 2 D 3 . The mechanism by which this is achieved is not known, but the results suggest that parathyroid hormone, Ca and P are unlikely to play roles in the adaptive increase in the level of 1, 25(OH) 2 D 3 in the blood of chicks given a minimal amount of D 3 . The possibility that the rate of degradation of 1, 25(OH) 2 D 3 is greatly reduced under these conditions cannot be excluded and this could account for the level of this metabolite in those birds.
Salecan is a recently identified water-soluble viscous extracellular β-1,3-d-glucan polysaccharide from an Agrobacterium species. It is a high-molecular-mass polymer (about 2 × 106 Da) and composed of a linear chain of glucosyl residues linked through a repeat unit of seven β-(1,3) and two α-(1,3) glucosidic bonds. In the present study, we examined the effects of dietary Salecan fed at 2 and 5 % in a high-fat diet (64 % energy) in C57BL/6J mice. After 6 weeks, mice fed 2 and 5 % Salecan had significantly lower body weight, fat mass and percentage of body fat mass compared with those fed a high-fat cellulose (control) diet. Both the Salecan groups significantly and dose-dependently improved glucose tolerance, with a 9 and 26 % reduction of glucose AUC, respectively. Liver and adipose tissue weights were also significantly decreased by the Salecan treatment. Supplementation with 5 % Salecan led to lower serum TAG, total cholesterol (TC) and HDL-cholesterol (52, 18 and 19 %, respectively) and lower hepatic TAG by 56 % and TC by 22 % compared with the high-fat cellulose control group. Dietary Salecan intake caused an obvious elevation of fat in the faeces. Supplementation with Salecan disturbed bile acid-promoted emulsification and reduced the size of emulsion droplets in vitro. These results indicate that Salecan decreases fat absorption, improves glucose tolerance and has biologically important, dose-related effects on reducing high-fat diet-induced obesity.
Healthy young men were fed four diets for 2 weeks each providing natural fats containing palmitic acid (16 : 0) predominantly in the sn-1, 3 position of dietary TAG or containing 16 : 0 predominantly in the sn-2 position with low or high levels of linoleic acid (18 : 2n-6). Two treatments supplied 16 : 0 in the sn-1, 3 positions from palmstearin with low (3 % energy) or high (>7 % energy) 18 : 2n-6 and two treatments supplied 16 : 0 in the sn-2 position from lard with high or low levels of 18 : 2n-6. Diets contained 30-35 % energy as fat, 7-11 % energy as 16 : 0 and moderate levels of cholesterol. Fasting serum cholesterol and lipoprotein concentrations were measured. Cholesterol fractional synthesis rate (FSR) was determined by 2H incorporation. Diets providing 16 : 0 in the sn-2 position resulted in lower fasting serum total cholesterol (TC) and a lower TC:HDL ratio than diets providing 16 : 0 in the sn-1, 3 positions. Diets with high levels of 18 : 2n-6 significantly decreased the TC:HDL ratio, reaffirming the well-known cholesterol-reducing effect of 18 : 2n-6. A lower non-esterified cholesterol FSR was observed with low dietary levels of 18 : 2n-6. No differences between dietary treatments were found for serum HDL-cholesterol, LDL-cholesterol or TAG. It is concluded that dietary fats containing 16 : 0 in the sn-2 position may result in slightly lower fasting TC than diets providing 16 : 0 in the sn-1, 3 positions, while the level of n-6 polyunsaturated fat influences endogenous cholesterol synthesis.
β-(1,3)-D-Glucan with β-(1,6) branches has been reported to have various pharmacological activities, such as anti-tumour and anti-infection activities, which result from its immunomodulating effects. Gastric lesions result from an imbalance between aggressive and defensive factors. In the present study, we examined the effect of β-(1,3)-D-glucan with β-(1,6) branches isolated from Aureobasidium pullulans on the gastric ulcerogenic response in mice. Oral administration of β-glucan ameliorated gastric lesions induced by ethanol (EtOH) or HCl. This administration of β-glucan also suppressed EtOH-induced inflammatory responses, such as infiltration of neutrophils and expression of pro-inflammatory cytokines, chemokines and cell adhesion molecules (CAM) at the gastric mucosa. Of the various defensive factors, the levels of heat shock protein (HSP) 70 and mucin but not PGE(2) were increased by the administration of β-glucan. β-Glucan-dependent induction of the expression of HSP70 and mucin proteins and suppression of the expression of pro-inflammatory cytokines, chemokines and CAM were also observed in cultured cells in vitro. The results of the present study suggest that β-glucan protects the gastric mucosa from the formation of irritant-induced lesions by increasing the levels of defensive factors, such as HSP70 and mucin.
Three experiments were undertaken to determine the effect of condensed tannin (CT) in Lotus pedunculatus (45-55 g extractable CT/kg DM) on the digestion of the principal leaf protein, ribulose-1,5-bisphosphate carboxylase (EC 220.127.116.11; Rubisco; fraction 1 leaf protein). In two of the experiments Lotus pedunculatus was fed to sheep, with one group receiving a continuous intraruminal infusion (per fistulum) of PEG (molecular weight 3500) to bind and inactivate the CT (PEG group). The other group, which did not receive PEG, was termed the control sheep (CT acting). Expt 3 involved in vitro incubations of Lotus pedunculatus in buffered rumen fluid, with and without PEG added. In all experiments the results have been interpreted in terms of the effects of CT on Rubisco solubilization and degradation. Disappearance of N and Rubisco from Lotus pedunculatus suspended in polyester bags in the rumen was used as a measure of solubilization. Degradation was defined as the disappearance of Rubisco from in vitro incubations of Lotus pedunculatus in rumen fluid. In Expt 1, CT reduced the digestion of Rubisco in the rumen from 0.96 to 0.72 of intake (P < 0.01). Rubisco digestion in the small intestine was 0.27 of intake in control sheep and 0.04 of intake in PEG sheep. In Expt 2, PEG had no effect on the loss of Rubisco from Lotus pedunculatus contained in polyester bags which were incubated in the rumen, hence CT did not affect the solubilization of Rubisco. Observations in Expt 1 were confirmed by in vitro incubations in Expt 3, where PEG addition substantially increased the rate of degradation of plant protein to NH3. Addition of PEG decreased the period of time taken to degrade 50% of the Rubisco from about 13.8 h to about 3.0 h. It was concluded that the action of CT reduced the digestion of Rubisco in the rumen of sheep fed on fresh Lotus pedunculatus, and that this was primarily due to the ability of CT to slow its degradation by rumen micro-organisms, without affecting its solubilization. Both fresh-minced, and freeze-dried and ground lotus were used for in sacco and in vitro incubations; however, fresh-minced lotus was more suitable for the evaluation of protein solubilization and degradation in fresh forages.
The effects of acarbose on cataract development, lens aldose reductase (EC 18.104.22.168) activity and lenticular reduced-glutathione content in diabetic sand rats (Psammomys obesus) were determined. Diabetic sand rats (diet-induced) were fed on diets with or without acarbose (0.4 g/kg) for 39 d. Daily plasma glucose, cataract incidence, aldose reductase and glutathione content were evaluated. After 19 d on acarbose, daily plasma glucose profile was significantly reduced compared with that of sand rats not receiving acarbose. Cataract incidence was markedly lower in sand rats treated with acarbose. After 20 d, cataracts had developed in 90% of the animals fed without acarbose, whereas none was observed in sand rats fed with acarbose. After 37 d acarbose treatment the incidence of cataracts reached only 30%. Compared with untreated animals, lens aldose reductase activity was significantly lower in sand rats fed with acarbose for 39 d (7.6 (SE 0.78) v. 3.5 (SE 0.55) mumol NADPH/mg protein per min respectively, P < 0.001). Concomitantly, significantly higher lenticular protein and reduced-glutathione contents (90 (SE 23) v. 240 (SE 23.5) micrograms/mg tissue respectively, P < 0.001 and 369 (SE 48.6) v. 645 (SE 71.1) micrograms/mg tissue respectively, P < 0.001) were found. These results suggest that decreasing hyperglycaemia, accompanied by lower aldose reductase activity obtained by acarbose, led to a significant preventive effect on cataract development in sand rats.
1. Vitamin E and selenium deficiencies were produced in the Pekin duckling ( Anser cinerens ) and were characterized by the development of lesions after 14 d in gizzard, intestine, heart and skeletal muscle.
2. The activities of glutathione peroxidase ( EC 22.214.171.124), using hydrogen peroxide and cumene hydroperoxide as substrates, glutathione-S-transferase ( EC 126.96.36.199), superoxide dismutase ( EC 188.8.131.52) and catalase ( EC 184.108.40.206) were measured in homogenate supernatant fractions of liver, heart, intestine, gizzard and skeletal muscle of deficient ducklings and of control birds given vitamin E or Se or both.
3. Glutathione peroxidase activities were dramatically lower in tissues of Se-deficient ducklings, and this was unaffected by vitamin E. No adaptive changes were seen in the activity of the other enzymes, even after 21 d when the deficiency was severe.
4. It appeared likely that the variability of the enzyme activities, other than glutathione peroxidase, in the different tissues studied might explain differences among the tissues in susceptibility to peroxidative damage.
1. Erythrocyte, plasma and whole blood selenium concentrations and glutathione peroxidase (EC I.11. 1.9; GSHPx) activities were measured (1) in 104 healthy New Zealand residents living in Otago, a low-soil-Se area (2) in sixty-four surgical patients, including nineteen patients on total parenteral nutrition and twenty-three cancer patients (3) in fifty-two ‘overseas subjects’ (twenty-five visitors to Otago from outside New Zealand and twenty-seven Otago residents on return from overseas travel).
2. Blood Se concentrations reflected dietary Se intake; means for Otago patients, healthy subjects and overseas subjects were different (0043, 0.059, 0.136 μg Se/ml blood respectively) and mean for overseas residents was greater than for New Zealand overseas travellers.
3. Erythrocyte Se concentration was always greater than plasma Se, and plasma Se was a smaller pro- portion of erythrocyte Se for patients compared with the controls.
4. GSHPx activities were different in the three groups, and vaned directly with erythrocyte Se until a plateau was reached at approximately 0.14 μg Se/ml erythrocytes.
5. Overseas subjects showed no relationship between erythrocyte Se and GSHPx activity. This agrees with some overseas studies and the significance of this finding is discussed.
6. Plasma Se concentration remained the most sensitive index of short-term changes in Se status, and erythrocyte Se and GSHPx activities for long-term changes in New Zealand subjects. Use of these measure- ments for overseas subjects with higher blood levels is discussed.
Riboflavin deficiency interferes with the growth and multiplication of malaria parasites as well as the host response to malaria. The objective of the present work was to determine the effects of riboflavin deficiency on erythrocyte glutathione peroxidase (EC 220.127.116.11; GPx) and superoxide dismutase (EC 18.104.22.168; SOD) in rats infected with Plasmodium berghei malaria. Riboflavin in its co-enzyme form, FAD, is required by glutathione reductase (EC 22.214.171.124) to regenerate GSH and GSH is an important cellular antioxidant both in its own right and also as a substrate for the enzyme GPx. Weanling rats were deprived of riboflavin for 8 weeks before intraperitoneal injection of 1 x 10(6) P. berghei parasites. Control animals were weight-matched to the respective riboflavin-deficient group. At 10 d post-infection, parasite counts were higher in the weight-matched control group than the riboflavin-deficient group (P = 0.004). GPx activity was higher in erythrocytes of rats parasitized with P. berghei than comparable non-infected rats regardless of riboflavin status (P < 0.05). As mature erythrocytes do not synthesize new protein, the higher GPx activities were probably due to the presence of the parasite protein. In erythrocytes from riboflavin-deficient rats, GPx activity tended to be lower than in those rats fed on diets adequate in riboflavin (weight-matched controls) whether parasitized or not, but the difference was not significant. Neither riboflavin deficiency nor malaria had any effect on erythrocyte SOD activity. It was concluded that riboflavin deficiency has no marked effect on erythrocyte GPx or SOD activity in the rat.
In Sweden fish is considered to be an important source of dietary Se. Therefore Se status was assessed in forty-one middle-aged men with widely varying fish consumption. Glutathione peroxidase (EC 126.96.36.199) and selenoprotein P in plasma were measured by radioimmunoassay. Plasma Se among the men increased slightly with increasing consumption of fish, but no such increases in the concentrations of glutathione peroxidase and selenoprotein P in plasma were observed. Moreover, no correlation was found between plasma Se and glutathione peroxidase or selenoprotein P. Instead, glutathione peroxidase was significantly correlated with selenoprotein P (r 0.73, P < 0.001), indicating that both glutathione peroxidase and selenoprotein P were functional indicators of Se status in this group. The proportion of plasma Se located in glutathione peroxidase decreased with increasing plasma Se. The results suggest that the Se consumed from fish had no apparent effect on the amount of Se incorporated into the functional selenoproteins of plasma. It is concluded that in some cases selenoproteins may be better biological markers of Se status than the total concentration of Se.
The bioavailability of Se from ground beef has been previously found in this laboratory to be greater than that of selenite or selenate when fed to female Fischer 344 rats. In the present study we examined the bioavailability of Se from various commercial portions of beef, the liver, striploin, round, shoulder and brisket. All beef was cooked, freeze-dried, finely powdered and mixed with the other dietary ingredients. The experimental diets were fed to the weanling Fischer 344 rats which had been subjected to dietary depletion of Se for 6 weeks. The bioavailability of Se from the beef diets was compared with that of Se as selenite or L-selenomethionine (SeMet) added to torula-yeast diets. Each experimental diet contained 0.10 mg Se/kg. After 8 weeks of dietary Se repletion, relative activity of liver glutathione peroxidase (EC 188.8.131.52; GSHPx) from the different dietary groups compared with that of control animals (100%) was (%): selenite 91, SeMet 122 (P < 0.05), liver 108, striploin 105, round 106, shoulder 106, brisket 103. Se recovery for liver GSHPx was generally highest from SeMet > beef muscle = beef liver > selenite. Muscle tissue deposition of Se was highest from SeMet > beef muscle > selenite = beef liver. In addition, the faecal excretion of Se was lowest from the SeMet dietary group and highest from the selenite dietary group. The experimental results suggest that all cuts of beef appear to be highly bioavailable sources of dietary Se when compared with selenite or L-SeMet.
1. The effect of dietary methionine on the utilization of selenium from dietary selenomethionine ([Se]Met) for tissue Se deposition and for glutathione peroxidase ( EC 184.108.40.206; GSH-Px) synthesis was studied in male weanling rats.
2. When rats were given 0.5 mg Se as [Se]Met/kg diet supplemented with 0, 4 or 9 g methionine/kg, Se in plasma, erythrocytes, liver and muscle increased significantly over the 20 d period for all methionine-treatment groups. The increases in erythrocyte and muscle Se, however, were significantly higher in rats fed on the methionine-deficient diet compared with the methionine-supplemented diets.
3. In contrast to the increases in tissue Se, GSH-Px activity in liver, plasma and muscle decreased in methionine-deficient rats given 0.5 mg Se as [Se]Met/kg whereas GSH-Px activity was maintained or increased in rats supplemented with methionine.
4. The percentage of tissue Se associated with GSH-Px was calculated from the measured Se concentration and GSH-Px activity. A significantly lower percentage of Se was associated with GSH-Px in methionine-deficient rats compared with methionine-supplemented rats.
5. These results show that Se from dietary [Se]Met is preferentially incorporated into body proteins rather than used for GSH-Px synthesis when methionine is limiting in the diet.
6. These results further suggest that [Se]Met might not be the optimum Se compound to use for Se supplementation because metabolism of dietary [Se]Met to a biochemically active form, such as GSH-Px, was impaired when [Se]Met was provided in diets low in methionine.
1. Two duplicate groups of rainbow trout ( Sulmo gairdneri ; mean weight 27 g) were given diets of differing selenium content (deficient 0, 025 mg Se/kg; supplemented 1.022 mg Se/kg) for 30 weeks.
2. There were no significant differences between treatments in weight gain but packed cell volume, liver vitamin E and liver and plasma Se concentrations were all significantly lower in the Se-deficient trout.
3. Ataxia occurred in about 10% of the Se-deficient trout and histopathologies were evident in nerve cord (damage to axon sheath) and liver (loss of integrity in endoplasmic reticulum and mitochondria with appearance of increased vesiculation).
4. Glutathione peroxidase ( EC 220.127.116.11) activity was significantly reduced in liver and plasma of Se-deficient fish but there was no indication, from differential assay, of any non-Se-dependent glutathione peroxidase activity. Glutathione transferase ( EC 2.5. I.18) activity was significantly increased in Se-deficient trout.
The selenium content of the 1989 harvest of wheat used for bread making in Scotland ranged from 0.028 microgram/g dry weight for home-grown wheat to 0.518 microgram/g for Canadian wheat. The tonnage values indicate that 13.8% of the wheat used in bread making came from Canada. This reflects in a calculated dietary intake of 31 micrograms/d which is well below the recommended levels of 70 and 55 micrograms for adult males and females respectively (National Research Council, 1989). The average glutathione peroxidase (EC 18.104.22.168) level in 478 samples of human whole blood was 6.08 (SE 0.065) units/ml. This increased to 6.65 (SE 0.321) in sixty-two subjects consuming brown or wholemeal bread but was unaffected by oily fish consumption. Analysis of a small number of samples of whole milk, eggs and meat indicated slightly higher concentrations than previously published values but this trend was insufficient to compensate for the lower cereal provision of Se.
Thirty-three New Zealand women aged 18-23 years received daily for 32 weeks, 200 micrograms Se as Se-enriched yeast (selenomethionine), or brewer's yeast mixed with selenate, or no added Se (placebo) in a double-blind trial. Se supplementation raised (P = 0.001) platelet glutathione peroxidase (EC 22.214.171.124; GSHPx) activity, and also Se and GSHPx in whole blood, erythrocytes and plasma. Selenomethionine was more effective in raising blood Se concentrations than selenate, but both were equally effective in raising GSHPx activities in whole blood, erythrocytes and plasma, indicating a similar bioavailability for the two forms. These observations and those of gel filtration studies of erythrocytes and plasma proteins reported elsewhere (Butler et al. 1991) are consistent with the incorporation of Se from selenomethionine into a general tissue protein pool while selenate is directly available for GSHPx synthesis, and explain the poorer correlation between Se and GSHPx in individuals with higher Se status. However, selenate raised platelet GSHPx activities to a greater extent than did selenomethionine suggesting some other effect of selenate on platelets which needs further investigation. A response of GSHPx activity in these New Zealand subjects indicates that their dietary Se intake is insufficient to meet recommended intakes based on the criterion of saturation of GSHPx activity, and could reflect a marginal Se status. The level of blood Se necessary for saturation of GSHPx of about 100 ng Se/ml whole blood confirms observations in earlier studies.
beta-Carotene-15,15'-dioxygenase (EC 126.96.36.199; beta-carotene dioxygenase) activity in extracts from guinea-pig intestinal mucosa was assayed by supplying [15,15'-14C2]- or [15,15'-3H2] beta-carotene dissolved in Tween 80. Methods were developed to minimize the breakdown of labelled beta-carotene and beta-carotene cleavage products during the isolation procedure. Antioxidants and unlabelled carriers were added to extracting solvents and C18 Sep-Pak cartridges were used to isolate the remaining beta-carotene and retinaldehyde, which was the only cleavage product detected. The labelled material produced by the enzyme was analysed by either normal-phase TLC or reversed-phase HPLC and characterized chemically as retinaldehyde. The lack of other labelled apo-carotenals isolated in these experiments and the formation of between 1.5 and 2 mol retinaldehyde/mol beta-carotene consumed confirm the central cleavage mechanism for the enzyme's action. More beta-carotene dioxygenase activity was obtained from guinea-pig mucosa than from chicken or pig intestinal mucosa. The beta-carotene dioxygenase was obtained as a soluble enzyme which was partially purified by gel filtration and ion-exchange chromatography to a specific activity of 0.6 nmol retinaldehyde formed/mg protein per h. The formation of a lipid-protein aggregate containing the beta-carotene dioxygenase activity, which has been reported to be present in the exclusion volume of Sephadex columns, was avoided if the mucosal scrapings were homogenized in buffer at a proportion of 1:4 (w/v).
1. Female weanling rats were fed on a purified diet containing either no vitamin A, apart from traces present in casein (deficient groups), or the same diet containing 1.55 mg retinol as retinyl acetate/kg (control groups). In one experiment the deficient groups were given 1 microgram retinol/d after 10 weeks, to permit successful reproduction under conditions of marginal vitamin A status. A proportion were mated at 11 weeks after weaning, and fetal development was permitted for 7 d or for 20 d before killing. 2. Carotene dioxygenase (EC 188.8.131.52) activity was measured in a supernatant fraction from intestinal mucosal scrapings. For each group, activity was 20-30% greater in the vitamin-A-deficient animals than in the controls, and the difference reached statistical significance for the virgin and 7 d pregnant animals in the first experiment (severe deficiency) and for the 20 d pregnant animals in the second experiment (less-severe deficiency). 3. It is suggested that low tissue vitamin A levels may feedback to increase carotene dioxygenase activity, by mechanisms at present unknown, presumably to ensure a more efficient use of precursor dietary carotenoids.
The aim of the present work was to investigate the influence of the intestinal microflora on the changes in hepatic cytochrome P450 apoproteins induced by dietary glucosinolates. Ten rats harbouring a conventional digestive microflora were offered either a diet containing 390 g myrosinase-free rapeseed meal/kg (n 5) or a control diet devoid of glucosinolates (n 5). A similar trial was performed using germ-free rats. After 4 weeks of exposure to the dietary regimens, animals were slaughtered and their livers removed for preparation of microsomes and analysis of cytochrome P450 (EC 184.108.40.206). The glucosinolate-rich diet decreased the concentration of total cytochrome P450 in conventional rats only (-34%). The bacterial status did not modify the concentration of apoproteins CYP1A2 and CYP2B1/B2, but greatly decreased the concentration of the male constitutive isoform CYP2C11 (-53 and -45% respectively in conventional and germ-free rats). Germ-free rats fed on the glucosinolate-rich diet had a greater concentration of CYP3A (+139%) and a lower concentration of CYP2E1 (-32%) than their counterparts fed on the control diet. However, these differences were absent in conventional animals. On the whole, the influence of the intestinal microflora on the changes in hepatic cytochrome P450 due to the consumption of cruciferous vegetables is very complex and obviously involves different mechanisms according to the apoprotein.
The effects of protein restriction on delta 9 desaturase (EC 220.127.116.11) activity were studied in growing rats. A control group was fed on a balanced diet (200 g casein/kg; BD) for 28 d. The experimental group was fed on the low-protein diet (20 g casein/kg; LP) for 26 d, then refed the balanced diet (BD-R) for 2 d. Rats were born to and suckled from normally fed dams. The enzyme activity was measured after 2 and 14 d of LP, and 26 d of LP plus 2 d of BD-R, by incubations in vitro of hepatic microsomal pellets with [1-14C]steric acid. The results indicated a decreased delta 9 desaturase activity after 2 and 14 d of LP of -33 and -43% respectively. Refeeding for 2 d was sufficient to super-repair this activity (+66%). The fatty acid composition of total liver lipids and microsomal phosphatidylethanolamines (PE) and phosphatidylcholines (PC) were also investigated; 18:0 decreased in total liver lipids at 14 d of LP, when 18:1n-9 increased. Stearic acid (18:0) increased in PC at 2 d of LP and in PE at 14 d of LP; oleic acid (18:1n-9) did not change. Therefore, it is concluded that a defect occurred in the bioconversion of 18:0 into 18:1n-9 by delta 9 desaturation during protein depletion. As oleic acid is accumulated in total liver lipids during LP, we speculate that this is due to a decreased oxidation or transport of this fatty acid.
1. Rats were given low-fat diets for 3 d in which the carbohydrate source was starch. The livers of animals given the fructose or sucrose had increased hepatic activities of the fatty acid synthetase and stearoyl CoA desaturase ( EC 18.104.22.168) enzyme complexes: in those given fructose there was a lower activity of the enzymes in adipose tissue.
2. Similar results were obtained in rats given fructose diets for 30 d, but in animals which had previously been made diabetic with streptozotocin, the activities were lower. The dietary treatment made little difference to the fatty acid profiles of the tissue lipids. The diabetic condition on the other hand produced considerable changes in fatty acid profile.
3. With diets containing approximately 200 g fat/kg in the form of butter or of polyunsaturated margarine, the tissue lipids from rats given sucrose had less linoleic acid than those from rats given starch. In addition, there was the expected difference between the rats given butter or margarine. The results are discussed in relation to the current literature.
1. The activity of superoxide dismutase (EC 22.214.171.124) was not greatly affected by zinc deficiency in maternal or foetal (20 d) rat livers, although in the latter tissue it did appear to be slightly raised by Zn depletion when compared with pair-fed control animals. 2. Enzyme activity was significantly higher in livers from all foetuses after administration of aqueous ethanol at 100 or 200 ml/l to the dams during pregnancy. 3. Plasma Zn levels were significantly increased in Zn-deficient dams after ingestion of alcohol during pregnancy.
1. The activity of manganese-superoxide dismutase ( EC 1.15.1; SOD) was increased in the livers and kidneys of adult rats after exposure to aqueous ethanol (200 ml/l) for 32 weeks.
2. The concentration of Mn in the livers and kidneys was significantly higher after 24 weeks, and by 32 weeks liver copper and zinc levels were lower.
3. The activity of foetal (day 19) liver superoxide dismutase was appreciably higher in offspring from dams receiving ethanol during pregnancy. Quantitatively the response appeared to be almost entirely due to the Mn-SOD form of the enzyme.
4. Maternal alcoholism during pregnancy had no effect on the levels of Cu, Mn or Zn in foetal (day 19) livers.
1. Studies have been made on the effects of dietary copper on the iron and Cu distribution in rats and on the metabolic activity and absorptive capacity of intestines perfused both vascularly and luminally.
2. Rats maintained for 4–5 weeks on a Cu-deficient diet (0.4μg Cu/kg) had significantly lower plasma, liver and intestinal Cu concentrations and significantly reduced plasma caeruloplasmin and liver cytochrome c oxidase ( EC 126.96.36.199) activity compared with controls receiving a Cu-supplemented diet (5 μg Cu/kg). Disturbances in Fe metabolism in Cu-deficient rats were evident as shown by a mild anaemia, significantly elevated hepatic Fe concentrations and hypoferraemia.
3. Intestinal glucose uptake from both the luminal perfusion medium (LPM) and vascular perfusion medium (VPM) was unaffected by Cu deficiency despite a significant (25–30 %) reduction in oxygen consumption. This was associated with a 40% decline in mucosal cytochrome c oxidase activity.
4. In studies of Fe absorption, Fe uptake from the LPM was unaffected by Cu deficiency while transfer of Fe to VPM was significantly reduced (50%) compared with control preparations. Addition of apotransferrin (1 g/l) to the VPM was without effect in preparations from control rats but significantly increased the transfer of Fe to the VPM in preparations from Cu-deficient rats without affecting Fe uptake from the LPM.
5. The addition of either human or porcine caeruloplasmin (together with apotransferrin) to the VPM, such that the resultant ferroxidase ( EC 188.8.131.52) activity of the VPM supernatant fraction was four to five times that of normal rat plasma, was without effect on either Fe uptake, tissue retention or Fe transfer to the VPM by preparations from either Cu-deficient or control rats.
6. These findings offer no evidence in support of the proposed role for caeruloplasmin with its associated ferroxidase activity in Fe absorption in the rat.
1. The effect of acute duodenal infusion of ⁹⁹ Mo-labelled sodium tetrathiomolybdate on caeruloplasmin (ferroxidase; EC 184.108.40.206) was examined in sheep. The diamine oxidase activity of this enzyme with respect to two substrates, p -phenylenediamine and o -dianisidine (both at their apparent K m concentrations) was inhibited.
2. The ⁹⁹ Mo appeared rapidly in plasma and was at first present predominantly in a trichloroacetic acid insoluble form; inhibition of oxidase activity was related to the levels of TCA-insoluble Mo. The behaviour of the copper prosthetic groups of caeruloplasmin was altered since some plasma Cu precipitated with the protein fraction after TCA treatment. The appearance of TCA insoluble Cu was related to the level of TCA-insoluble ⁹⁹ Mo and corresponded to the inhibition of diamine oxidase activity.
1. The effect of peroral administration of xylitol on the absorption of iron and the activities of xanthine oxidase (EC 1. 2. 3. 2) and ferroxidase in rat duodenal wall was studied.
2. Adult male rats were given the basal diet containing 200 g xylitol/kg or the same diet containing no added carbohydrates for 8 weeks. Both feeding groups comprised twelve animals.
3. Xylitol significantly increased serum and liver Fe concentrations with a concomitant, significant increase in the duodenal xanthine oxidase activities, but caused a marginal increase in the duodenal ferroxidase activities.
4. In vitro, sugar alcohols reduced the binding rate of Fe to transferrin.
5. The xylitol-induced increase of Fe absorption may involve the following mechanism: the high intraluminal xylitol concentration of the xylitol-fed rats keeps Fe in the form of a soluble complex for a prolonged period of time, due to the slow absorption of xylitol. The polyol-Fe complex in turn induces xanthine oxidase and ferroxidase formation.
The urinary excretion of purine derivatives (PD) was measured in six buffaloes (Bubalis bubalis) during fasting and in fourteen buffaloes given four restricted levels of roughage (2.5-4.8 kg DM/d). Only allantoin and uric acid, not xanthine and hypoxanthine, were present in the urine, the pattern of excretion being similar to that in cattle. The fasting PD excretion amounted to 0.20 (SD 0.06) mmol/kg metabolic weight (W)0.75 per d, and the rate of PD excretion as a linear function of feed intake was 5.2 mmol/kg digestible organic matter intake. Both values were considerably lower than the values for cattle reported in the literature. Creatinine excretion values were 0.33 (SD 0.06) and 0.44 (SD 0.09) mmol/kg (W)0.75 per d determined in fasting and feeding periods respectively. Fasting N excretion was 257 (SD 49) mg N/kg (W)0.75 per d. Both creatinine and fasting N excretions were also lower than in cattle. The activities of xanthine oxidase (EC 220.127.116.11) in plasma, liver and intestinal mucosa were determined in buffaloes, cattle and sheep. Xanthine oxidase activities in buffaloes were 24.5 (SD 2.7) unit/l plasma and 0.44 (SD 0.02) and 0.31 (SD 0.10) unit/g fresh tissue in liver and intestinal mucosa respectively. These activities were higher than those in cattle and sheep. Xanthine oxidase was practically absent from plasma and intestine of sheep. It is suggested that the differences in PD excretion between buffaloes and cattle were probably due to the smaller proportion of plasma PD that was disposed of in the urine of buffaloes.
1. Branched-chain amino acid aminotransferase ( EC 18.104.22.168; BCAAT) and branched-chain α-keto acid dehydrogenase ( EC 22.214.171.124; BCKDH) activities were measured in preruminant lamb liver, longissimus dorsi muscle, kidney, jejunum and adipose tissue, 2 h after a meal with or without an excess of leucine.
2. Skeletal muscle contained about 70% of the total basal BCAAT activities of the tissues studied whereas liver contained about 60% of the total BCKDH activities of these tissues.
3. BCAAT activities were very low in preruminant lamb tissues. BCKDH was more phosphorylated in tissues of preruminant lambs than in rats, especially in liver. These low catalytic potentialities might contribute to a low rate of branched-chain amino acid catabolism in sheep.
4. Ingestion of an excess of leucine led to an increase in liver and jejunum BCAAT activities and activation of BCKDH in jejunum.
Because of its strong association (r 0·85) with percentage of body fat determined by dual-energy X-ray absorptiometry, hip circumference divided by height1·5 (the body adiposity index) has recently been proposed as an index of body fatness among adults. We examined whether this proposed index was more strongly associated with skinfold thicknesses and levels of CVD risk factors (lipids, fasting insulin and glucose, and blood pressure) than was BMI among 2369 18- to 49-year-olds in the Bogalusa Heart Study. All analyses indicated that the body adiposity index was less strongly associated with skinfold thicknesses and CVD risk factors than was either waist circumference or BMI. Correlations with the skinfold sum, for example, were r 0·81 (BMI) v.
r 0·75 (body adiposity index) among men, and r 0·87 (BMI) v.
r 0·80 among women; P< 0·001 for both differences. An overall index of seven CVD risk factors was also more strongly associated with BMI (r 0·58) and waist circumference (r 0·61) than with the body adiposity index (r 0·49). The weaker associations with the body adiposity index were observed in analyses stratified by sex, race, age and year of examination. Multivariable analyses indicated that if either BMI or waist circumference were known, the body adiposity index provided no additional information on skinfold thicknesses or risk factor levels. These findings indicate that the body adiposity index is likely to be an inferior index of adiposity than is either BMI or waist circumference.
1. Riboflavin deficiency at two levels of severity was produced in weanling rats by feeding deficient diets for 6 weeks and using neck collars to prevent coprophagy. The severity of deficiency was monitored by growth, liver flavin levels and the activation coefficient of erythrocyte glutathione oxidoreductase (NAD(P)H) (EC 1. 6. 4. 2 ) Control groups, receiving the same diet with ample added riboflavin, were fed either ad lib. , or were pair-fed with the deficient animals.
2. The hepatic flavoenzyme, methylenetetrahydrofolate reductase (NADPH) (EC 126.96.36.199), was very markedly affected by severe riboflavin deficiency and was significantly, but less markedly, affected by the intermediate level of deficiency. This reduction in activity was due primarily to the direct effect of the diminished supply of riboflavin, and occurred to only a small extent as a result of inanition, demonstrated by a moderate reduction in activity in the more severely food-restricted of the two pair-fed groups. Since the enzyme is assayed in the presence of its flavin cofactor, FAD, it clearly cannot be reactivated in vitro, as some other depleted flavoenzymes can. The discriminatory ability in distinguishing between severe and moderate riboflavin deficiency in vivo confers some potential advantages on this oxidoreductase as a possible index of riboflavin status.
3. The hepatic activity of another key folate-metabolizing enzyme, dihydrofolate reductase (EC 188.8.131.52), was not diminished by riboflavin deficiency in the present study.
4. The ratio, labelled 5-methyltetrahydrofolic acid: other labelled compounds derived from intraperitoneally injected pteroylglutamic acid in extracts of hepatic tissue was significantly reduced in the riboflavin-deficient groups, indicating the possibility of an effect of riboflavin deficiency on folate metabolism in vivo.
1. Chronic marginal riboflavin deficiency was induced in groups of weanling rats by feeding a deficient diet supplemented with 0, 0.5, 1.0 and 1.5 mg riboflavin/kg diet. Ad lib.- and pair-fed controls received 3.0 and 15 mg riboflavin/kg diet respectively. 2. Serial measurement of erythrocyte NAD(P)H2 glutathione oxidoreductase (glutathione reductase; EC 184.108.40.206) and its activation coefficient revealed that after 12 weeks a steady-state of deficiency had been reached following initial fluctuations in status; the animals were then killed, and their tissues analysed. 3. Food intake, growth rate and the appearance of pathological signs were directly proportional to riboflavin content; however relative liver weight was increased above control levels only in the most-severely-deficient group, and anaemia was not detected in any group. 4. The activation coefficient of glutathione reductase in erythrocytes and liver was closely related to dietary riboflavin content; that of skin responded maximally even in the least-severely-depleted animals. 5. Hepatic and renal flavin contents were directly proportional to dietary riboflavin, FAD being conserved at the expense of riboflavin and FMN. ATP:riboflavin 5-phosphotransferase (flavokinase; EC 220.127.116.11) activity was reduced, even in the least-severely-deficient animals; ATP:FMN adenylyltransferase(FAD pyrophosphorylase; EC 18.104.22.168) was increased in liver, but only in the most-severely-deficient animals. 6. Hepatic succinate:(acceptor) oxidoreductase (succinate dehydrogenase; EC 22.214.171.124) activity fell sharply between 1.5 and 0.5 mg riboflavin/kg diet, producing an S-shaped dose-response curve; it showed smaller or less specific changes in other tissues such as brain, skin and intestine. NADH:(acceptor) oxidoreductase (NADH dehydrogenase; EC 126.96.36.199) activity declined in liver and intestine, but not in skin or brain. 7. The activation coefficient of glutathione reductase was correlated strongly with nearly all the riboflavin-sensitive variables measured, once equilibrium had been reached in this chronic deficiency model, and it was particularly strongly correlated with hepatic and renal FAD levels. Under equilibrium conditions, therefore, it appears to represent a good index of the extent of riboflavin deficiency, and significant changes in flavin levels and enzymes in the internal organs were detected even under conditions of marginal deficiency, associated with relatively small increases in the activation coefficient.
1. Some modifications to the erythrocyte glutathione reductase assay for riboflavin status are described.
2. Cusum analysis of results collected on a quality-control (QC) haemolysate, analysedseparately at the beginning and end of each batch of samples over a period of 20 weeks, suggested that the activation coefficient (AC) was higher at the end of a batch than at the beginning.
3. The higher AC was due to higher FAD-stimulated enzyme activities of the QC samples measured at the end of the day, by comparison with the beginning, and this suggested that the conditions of assay were not optimal.
4. The conditions required to achieve maximal coupling of FAD to glutathione reductase(NAD(P)H 2 : glutathione oxidoreductase; EC 188.8.131.52) were therefore examined and found to be 15 min at 35° by comparison with the 5–7 min incubation used by most workers.
5. Alternatively, where samples are prepared in batches, the enzyme and FAD should be pre-incubated in the reaction mixture for 2 h at 4° or 1 h at 25° before the standard incubation of 5 min at 35°.
6. Additionally, the use of cummulative sum (cusum) analysis on the QC results suggested that there was a slight deterioration of QC sample after 4-weeks storage. However, theQC results obtained, remained within 2 standard deviations of initial results over a 20-week period, suggesting that the deterioration was very slight.
1. Chronic marginal riboflavin deficiency was induced in groups of weanling rats by feeding a deficient diet supplemented with 0, 0·5, 1·0 and 1·5 mg riboflavin/kg diet. Ad lib .- and pair-fed controls received 3·0 and 15 mg riboflavin/kg diet respectively.
2. Serial measurement of erythrocyte NAD(P)H 2 glutathione oxidoreductase (glutathione reductase; EC 184.108.40.206) and its activation coefficient revealed that after 12 weeks a steady-state of deficiency had been reached following initial fluctuations in status; the animals were then killed, and their tissues analysed.
3. Food intake, growth rate and the appearance of pathological signs were directly proportional to riboflavin content; however relative liver weight was increased above control levels only in the most-severelydeficient group, and anaemia was not detected in any group.
4. The activation coefficient of glutathione reductase in erythrocytes and liver was closely related to dietary riboflavin content; that of skin responded maximally even in the least-severelydepleted animals.
5. Hepatic and renal flavin contents were directly proportional to dietary riboflavin, FAD being conserved at the expense of ribotlavin and FMN . ATP : riboflavin 5-phosphotransferase (flavokinase; EC 220.127.116.11) activity was reduced, even in the least-severely deficient animals; ATP: FMN adenylyltransferase (FAD pyrophosphory1ase; EC 18.104.22.168) was increased in liver, but only in the most-severely-deficient animals.
6. Hepatic succinate: (acceptor) oxidoreductase (succinate dehydrogenase; EC 1. 3.99.1) activity fell sharply between 1·5 and 0·5 mg riboflavin/kg diet, producing an S -shaped dose-response curve; it showed smaller or less specific changes in other tissues such as brain, skin and intestine. NADH : (acceptor) oxidoreductase (NADH dehydrogenase; EC 22.214.171.124) activity declined in liver and intestine, but not in skin or brain.
7. Theactivation coefficient of glutathione reductase was correlated strongly with nearly all the riboflavin-sensitive variables measured, once equilibrium had been reached in this chronic deficiency model, and it was particularly strongly correlated with hepatic and renal FAD levels. Under equilibrium conditions, therefore, it appears to represent a good index of the extent of riboflavin deficiency, and significant changes in flavin levels and enzymes in the internal organs were detected even under conditions of marginal deficiency, associated with relatively small increases in the activation coefficient.
The aim of the present study was to obtain serial values of O2 consumption (VO2), CO2 production (VCO2) and energy expenditure (EE) in healthy but extremely-low-birth-weight infants (birth weight <1000 g), during the first 5 weeks after birth. A total of seventeen spontaneously breathing and appropriate-for-gestational-age (birth weight and body length above the 10th and below the 90th percentile) preterm infants with gestational age 25-28 weeks and birth weight 590-990 g were enrolled in the study. Calorimetry was performed using an open-circuit calorimeter on days 6, 12, 18, 24, 30 and 36 of postnatal life. During the 5 weeks of observation, VO2 increased from 4.7 (SD 0.5) to 9.1 (SD 1.0) ml/kg per min, VCO2 from 4.5 (SD 0.4) to 8.3 (SD 0.6) ml/kg per min and EE from 115 (SD 12) to 310 (SD 71) kJ/kg per d. The energy intake was always higher than EE, even at days 6 and 12. The RER decreased from 0.99 (SD 0.09) at day 12 to 0.91 (SD 0.05) at day 30. On all study days, there were highly significant positive correlations between energy intake and weight gain, EE and weight gain, and EE and energy intake (P<0.05). Multiple regression analysis showed that on most study days EE was more affected by energy intake than by weight gain. We conclude that in healthy preterm infants with birth weight <1000 g, EE increases by about 150 % in the first 5 weeks after birth, and that the EE values are related to energy intake and weight gain independent of postnatal age.
In the present study the relationship of sugar-sweetened beverage (SSB) consumption with the intake of single nutrients and total diet quality in German children and adolescents was evaluated using a repeated-measures regression analysis model. We used dietary data from 7145 three-day weighed records of 1069 subjects aged 2-19 years participating in the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study. Intake of macronutrients as percentage of total energy intake (%En), intake of micronutrients as percentage of German reference values (intake quality score) and nutritional quality index (NQI) as an indicator of diet quality were chosen as separate dependent variables. SSB consumption was positively associated with %En from carbohydrates (boys v. girls: +4.00 v. +4.09 En%/MJ from SSB) and added sugars (boys v. girls: +7.36 v. +9.52 En%/MJ from SSB) and negatively with %En from protein (boys v. girls: - 1.25 v. - 1.31 En%/MJ from SSB) and fat (boys: - 2.82 v. - 2.73 En%/MJ from SSB). With respect to micronutrients, SSB consumption was negatively associated with folate and Ca intake, for which mean intake levels were inadequate in girls. Absolute diet quality was negatively associated with SSB consumption, whereas the effect was larger for girls (boys v. girls: - 1.41 v. - 2.63 points of NQI/MJ from SSB). Overall, results show a diluting effect of SSB consumption on micronutrient intake and diet quality. This effect might be relevant especially in girls as the association with diet quality was larger and mean NQI levels were lower in comparison with boys.
Balanced glucose metabolism ensures optimal fetal growth with long-term health implications conferred on both mother and child. We examined whether supplementation of probiotics with dietary counselling affects glucose metabolism in normoglycaemic pregnant women. At the first trimester of pregnancy 256 women were randomised to receive nutrition counselling to modify dietary intake according to current recommendations or as controls; the dietary intervention group was further randomised to receive probiotics (Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12; diet/probiotics) or placebo (diet/placebo) in a double-blind manner, whilst the control group received placebo (control/placebo). Blood glucose concentrations were lowest in the diet/probiotics group during pregnancy (baseline-adjusted means 4.45, 4.60 and 4.56 mmol/l in diet/probiotics, diet/placebo and control/placebo, respectively; P = 0.025) and over the 12 months' postpartum period (baseline-adjusted means 4.87, 5.01 and 5.02 mmol/l; P = 0.025). Better glucose tolerance in the diet/probiotics group was confirmed by a reduced risk of elevated glucose concentration compared with the control/placebo group (OR 0.31 (95 % CI 0.12, 0.78); P = 0.013) as well as by the lowest insulin concentration (adjusted means 7.55, 9.32 and 9.27 mU/l; P = 0.032) and homeostasis model assessment (adjusted means 1.49, 1.90 and 1.88; P = 0.028) and the highest quantitative insulin sensitivity check index (adjusted means 0.37, 0.35 and 0.35; P = 0.028) during the last trimester of pregnancy. The effects observed extended over the 12-month postpartum period. The present study demonstrated that improved blood glucose control can be achieved by dietary counselling with probiotics even in a normoglycaemic population and thus may provide potential novel means for the prophylactic and therapeutic management of glucose disorders.