873 resultados para Free-living Strain
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In natural systems phytoplankton interact with planktonic (free living) and attached epiphytic bacteria both synergistically and antagonistically. The specificity of the association with micro algae and bacteria differs in terms of adhesion mechanisms and metabolic cooperation. Present research was carried out to study the effect of bacterial isolates namely Bacillus sp. and Pseudomonas sp. from algal culture systems on the growth of micro algae such as Chaetoceros calcitrans and Nannochloropsis oculata. C. calcitrans (F= 15.34; P<0.05) and N. oculata (F=12.52; P<0.05) showed significantly higher growth, in treatments with Bacillus sp. and Pseudomonas sp when compared to control.
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Gerade männliche Jugendliche nutzen in ihrer Pubertät und Adoleszenz zu einer gelingenden Gestaltung ihres Alltags und zur Ausbildung ihrer Identität zahlreiche Erscheinungsformen des Fantasy-Rollenspielens. In einem Prozess von Aneignung und Entäußerung integrieren dabei die Jugendlichen das überaus reiche multimediale Angebot, welches die Spiele bieten, in ihre Alltagsgestaltung, indem sie sich daraus spezifische Medien-, Text- und Ereignisarrangements bauen. Diese dienen einerseits der sozialen Integration und Distinktion, andererseits der Präsentation ihrer Identitätsentwürfe sich und anderen. Die Jugendlichen schaffen sich mittels dieser spezifischen Medien-, Text- und Ereignisarrangements eine in weiten Teilen von ihnen selbst bestimmte Welt, in der sie ihre Phantasie wie Kreativität mit großer Intensität, ja Obsession, innerhalb integrativer und solidarischer Interaktionsformen selbststeuernd und professionell ausleben. Diese Medien-, Text- und Ereignisarrangements zeigen Angebots- und Nutzungsformen, die sich nach einem medienkommunikativen Aneignungs- und Entäußerungsmodell in der Tradition der Cultural Studies (Stuart Hall) beschreiben lassen. Die Langzeitbeobachtung der Jugendlichen zeigt, dass sie alltagspragmatische Kulturtechniken zur selbstbestimmten Gestaltung von Alltag entwickeln: zunächst eine Strukturierung ihrer kognitiven, affektiven und pragmatischen Interaktion nach Kriterien erfolgreicher intrinsischer Interaktion, mit dem Ziel derer Perpetuierung im Flow-Erleben (Mihalyi Csikszentmihalyi), dann eine Ästhetisierung von Alltagswirklichkeit mittels kollektiver Fiktionalisierung in der Tradition des Collective Story Telling (Janet H. Murray). Diese Kulturtechniken stellen vor dem Hintergrund der Enkodierung und Dekodierung sozialer Codes spezifische Adaptionen von Prozessen der Bedeutungszuweisung und Subjekt- bzw. Identitätskonstitution dar. Die sie evozierenden und mit ihnen korrespondierenden handlungsleitenden Themen der Jugendlichen sind der Wunsch nach Rekonstitution von Gesamtheit in einer sich fragmentarisierenden Wirklichkeit, die Affirmation von Selbstbestimmung- und Autonomieerfahrungen, das Erleben von Reintegration und Solidarität für das sich dissoziiert erfahrende Individuum. Das Handeln der Jugendlichen basiert damit auf dem momentan dominanten Prozess einer Individualisierung von Lebenswelt unter den Bedingungen von Reflexivität und Erlebnisrationalität in der postmodernen Gesellschaft. Mit ihren Versuchen selbstbestimmter Gestaltung folgen sie dem aktuellen gesellschaftlichen Auftrag einer weitgehend in eigener Regie vorzunehmenden Lokalisierung dieses Prozesses. Zunehmend tritt diese von den Jugendlichen selbstgesteuerte Sozialisation neben die traditionell heteronome Sozialisation von gesellschaftlichen Instituten wie etwa die von Schule. Damit wird das Handeln der Jugendlichen zu einer Herausforderung an Pädagogik und Schule. Schule muss, wenn sie ihrem eigentlichen Auftrag von Förderung gerecht werden will, eine Sensibilität für diese Eigenständigkeit von Jugendlichen entwickeln und in der Beobachtung ihres Handelns didaktische Innovationen für Lehren und Lernen entwickeln. Im Mittelpunkt steht dabei die Wiederentdeckung des pädagogischen Dialogs, besonders aber die Entwicklung einer individualisierten Lernkultur und die Förderung jugendlicher Gestaltungskompetenzen, welche von deren alltagsästhetischen Erfahrungen und Kompetenzen im Umgang mit multimedialen Kulturprodukten ausgeht. Schule kann und muss für diese Prozesse selbstgesteuerten Lernens angemessene pädagogische Räume bereitstellen, in denen die Jugendlichen innerhalb eines geschützten Kontextes in der Auseinandersetzung mit eigenen wie fremden Entwürfen ihre Identität entwickeln können.
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This study was conducted to investigate soil biological and chemical factors that give rise to cereal yield enhancing effects of legume rotations on sandy, nutrient poor West African soils. The aim was not only to gain more information on the role of legume residues and microorganisms in the soil nutrient cycle. But the study aimed at evaluating if differences in substrate qualities (e.g. root residues) cause changes in the microbial community structure due to specific and highly complex microbe-root-soil interactions. Site and system specific reactions of microorganisms towards rewetting, simulating the onset of rainy season, were observed. Higher respiration rates, higher amounts of microbial biomass carbon (Cmic) and nitrogen (Nmic) as well as higher ergosterol, muramic acid, glucosamine and adenylate concentrations were measured in CL soils of Koukombo and in both soils from Fada. The immediate increase in ATP concentrations after rewetting was likely caused by rehydration of microbial cells where N was not immobilized and, thus, available for plants facilitating their rapid development. Legume root residues led only to slightly better plant performances compared to the control, while the application of cereal roots reduced seedling growth. In contrast to sorghum seedlings, the microbial community did not react to the mineral treatment. Thus the energy supply in form of organic amendments increased microbial indices compared to mineral P application and the control. The results of basal respiration rates, Cmic and Corg levels indicate that the microbial community in the soil from Koukombo is less efficient in substrate use compared to microorganisms in the soil from Fada. However, the continuous carbon input by legume root residues might have contributed to these differences in soil fertility. With the 33P isotopic exchange method a low buffering capacity was detected in both soils irrespective of treatments. Calculated E values (E1min to E1min-1d and E1d-3m) indicated a slowly release of P due to root turnover while applied mineral P is taken up by plants or fixed to the soil. Due to the fact that sorghum growth reacted mainly to the application of mineral P and the microorganisms solely to the organic inputs, the combination of both amendments seems to be the best approach to a sustainable increase of crop production on many nutrient-poor, sandy West African soils. In a pot experiment, were CC and CL soils from Fada and Koukombo were adjusted to the same level of P and N concentrations, crop growth was significantly higher on CL soils, compared to the respective treatments on CC soils. Mycorrhizal infection of roots was increased and the number of nematodes, predominantly free living nematodes, was almost halfed on rotation soils. In conclusion, increased nutrient availability (especially P and N) through the introduction of legumes is not the only reason for the observed yield increasing effects. Soil biological factors seem to also play an important role. In a root chamber experiment the pH gradient along the root-soil-interface was measured at three times using an antimony microelectrode. For Fada soils, pH values were higher on CL than CC soils while the opposite was true for the Koukombo soils. Site-specific differences between Fada and Koukombo soils in N content and microbial community structures might have created varying crop performances leading to the contrasting pH findings. However, the mechanisms involved in this highly complex microbe-root-soil interaction remain unclear.
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The phenolic compositions of fecal water samples from ten free-living human subjects without marked dietary restrictions were monitored before and after intake of raspberry puree (200 g/day, 4 days) using gas chromatography-mass spectrometry. No single phenolic component was increased in all subjects after intake, but a majority of subjects had significant elevations in phenylacetic acid (7/10), 4-hydroxyphenylacetic acid (6/10), 3-hydroxyphenylacetic acid (5/10), 3-phenylpropionic acid and 3-(4-hydroxyphenyl)propionic acid. The levels of 3,4-dihydroxbenzoic acid were elevated in 8/10 subjects, significantly for 6 subjects (p < 0.05), and not significantly reduced in the other 2 subjects. In addition, unlike most other fecal metabolites, the increase was always >2-fold. This metabolite may be representative of the increased colonic dose of cyanidin anthocyanins. The colonic microbiota varied greatly between individuals, and supplementation with raspberries did not produce any statistically significant alterations in the profile of colonic bacteria, nor was a common pattern revealed to account for the interindividual variations observed in the fecal water phenolic profiles.
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The Entomopathogenic bacterium Pseudomonas putida from Steinernema abbasi and its metabolic secretions were lethal to the Galleria mellonella larvae. Different laboratory experiments on time interval, substrate, moisture, temperature, dose, penetration of cells, stored and dried metabolites were conducted in sand and filter paper bioassays. It was concluded that death was probably due to the toxic metabolites. This bacterium and its metabolites were found very effective at 30 degree C. Penetration of bacterium was rapid after application on G. mellonella larvae. P. putida cells were recovered from the haemocoele when suspensions containing bacterial cells were applied to the G. mellonella indicating that bacterial symbionts do have a free-living existence and can enter the haemocoele in the absence of nematode vector. Stored metabolite and dried metabolites were found persistent for long time. This bacterium or its toxic secretions can be used for insect control that can be important component of integrated pest management against different insect pests. P. putida and its secretions are suggested as the most appropriate suspension to apply against insect pest control program in tropical ecological regions.
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Estimation of whole-grain (WG) food intake in epidemiological and nutritional studies is normally based on general diet FFQ, which are not designed to specifically capture WG intake. To estimate WG cereal intake, we developed a forty-three-item FFQ focused on cereal product intake over the past month. We validated this questionnaire against a 3-d-weighed food record (3DWFR) in thirty-one subjects living in the French-speaking part of Switzerland (nineteen female and twelve male). Subjects completed the FFQ on day 1 (FFQ1), the 3DWFR between days 2 and 13 and the FFQ again on day 14 (FFQ2). The subjects provided a fasting blood sample within 1 week of FFQ2. Total cereal intake, total WG intake, intake of individual cereals, intake of different groups of cereal products and alkylresorcinol (AR) intake were calculated from both FFQ and the 3DWFR. Plasma AR, possible biomarkers for WG wheat and rye intake were also analysed. The total WG intake for the 3DWFR, FFQ1, FFQ2 was 26 (sd 22), 28 (sd 25) and 21 (sd 16) g/d, respectively. Mean plasma AR concentration was 55.8 (sd 26.8) nmol/l. FFQ1, FFQ2 and plasma AR were correlated with the 3DWFR (r 0.72, 0.81 and 0.57, respectively). Adjustment for age, sex, BMI and total energy intake did not affect the results. This FFQ appears to give a rapid and adequate estimate of WG cereal intake in free-living subjects.
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Alanine dehydrogenase (AldA) is the principal enzyme with which pea bacteroids synthesize alanine de novo. In free-living culture, AMA activity is induced by carboxylic acids (succinate, malate, and pyruvate), although the best inducer is alanine. Measurement of the intracellular concentration of alanine showed that AldA contributes to net alanine synthesis in laboratory cultures. Divergently transcribed from aldA is an AsnC type regulator, aldR. Mutation of aldR prevents induction of AldA activity. Plasmid-borne gusA fusions showed that aldR is required for transcription of both aldA and aldR; hence, AldR is autoregulatory. However, plasmid fusions containing the aldA-aldR intergenic region could apparently titrate out AldR, sometimes resulting in a complete loss of AldA enzyme activity. Therefore, integrated aldR::gusA and aldA::gusA fusions, as well as Northern blotting, were used to confirm the induction of aldA activity. Both aldA and aldR were expressed in the II/III interzone and zone III of pea nodules. Overexpression of aldA in bacteroids did not alter the ability of pea plants to fix nitrogen, as measured by acetylene reduction, but caused a large reduction in the size and dry weight of plants. This suggests that overexpression of aldA impairs the ability of bacteroids to donate fixed nitrogen that the plant can productively assimilate. We propose that the role of AldA may be to balance the alanine level for optimal functioning of bacteroid metabolism rather than to synthesize alanine as the sole product of N-2 reduction.
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Objective: To determine whether consumption of five portions of fruit and vegetables per day reduces the enhancement of oxidative stress induced by consumption of fish oil. Subjects: A total of 18 free-living healthy smoking volunteers, aged 18-63 y, were recruited by posters and e-mail in The University of Reading, and by leaflets in local shops. Design: A prospective study. Setting: Hugh Sinclair Unit of Human Nutrition, School of Food Biosciences, The University of Reading, Whiteknights PO Box 226, Reading RG6 6AP, UK. Intervention: All subjects consumed a daily supplement of 4 x 1 g fish oil capsules for 9 weeks. After 3 weeks, they consumed an additional five portions of fruits and vegetables per day, and then they returned to their normal diet for the last 3 weeks of the study. Fasting blood samples were taken at the ends of weeks 0, 3, 6 and 9. Results: The plasma concentrations of ascorbic acid, lutein, beta-cryptoxanthin, alpha-carotene and beta-carotene all significantly increased when fruit and vegetable intake was enhanced (P<0.05). Plasma concentrations of α-tocopherol, retinol and uric acid did not change significantly during the period of increased fruit and vegetable consumption. Plasma oxidative stability, assessed by the oxygen radical absorbance capacity (ORAC) assay, also increased from weeks 3-6 (P<0.001) but not in association with increases in measured antioxidants. Lag phase before oxidation of low-density lipoprotein (LDL) significantly decreased in the first 3 weeks of the study, reflecting the incorporation of EPA and DHA into LDL (P<0.0001). Subsequent enhanced fruit and vegetable consumption significantly reduced the susceptibility of LDL to oxidation (P<0.005). Conclusion: Fish oil reduced the oxidative stability of plasma and LDL, but the effects were partially offset by the increased consumption of fruit and vegetables.
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Microbial biofilms were first described in 1936 and subsequent research has unveiled their ubiquity and physiological distinction from free-living (planktonic) microorganisms. In light of their emerging significance this review examines the bacterial biofilms within the human gastrointestinal tract. Attention is paid to the nature of these mucosally- associated populations, focusing on the protected environment afforded by the continual secretion of mucus by host epithelial cells. It also examines the attributes possessed by various bacterial species that facilitate habitation of this microenvironment. Additionally, contrasts are drawn between planktonic bacteria of the lumen and sessile (biofilm) bacteria growing in close association with host cells and food particles. In particular the different fermentation profiles exhibited by these two fractions are discussed. The potential role of these communities in host health and disease, as well as the stabilisation of the lumenal population, is also considered. Reference is made to the state of mutualism that exists between these little understood populations and the host epithelia, thus highlighting their ecological significance in terms of gastrointestinal health.
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Objective: To determine whether dietary supplementation with a natural carotenoid mixture counteracts the enhancement of oxidative stress induced by consumption of fish oil. Design: A randomised double-blind crossover dietary intervention. Setting: Hugh Sinclair Unit of Human Nutrition, School of Food Biosciences, The University of Reading, Whiteknights PO Box 226, Reading RG6 6AP, UK. Subjects and intervention: A total of 32 free-living healthy nonsmoking volunteers were recruited by posters and e-mails in The University of Reading. One volunteer withdrew during the study. The volunteers consumed a daily supplement comprising capsules containing fish oil (4 x 1 g) or fish oil (4 x 1 g) containing a natural carotenoid mixture (4 x 7.6 mg) for 3 weeks in a randomised crossover design separated by a 12 week washout phase. The carotenoid mixture provided a daily intake of beta-carotene (6.0 mg), alpha-carotene (1.4 mg), lycopene (4.5 mg), bixin (11.7 mg), lutein (4.4 mg) and paprika carotenoids (2.2 mg). Blood and urine samples were collected on days 0 and 21 of each dietary period. Results: The carotenoid mixture reduced the fall in ex vivo oxidative stability of low-density lipoprotein (LDL) induced by the fish oil (P = 0.045) and it reduced the extent of DNA damage assessed by the concentration of 8-hydroxy-2'-deoxyguanosine in urine (P = 0.005). There was no effect on the oxidative stability of plasma ex vivo assessed by the oxygen radical absorbance capacity test. beta- Carotene, alpha-carotene, lycopene and lutein were increased in the plasma of subjects consuming the carotenoid mixture. Plasma triglyceride levels were reduced significantly more than the reduction for the fish oil control (P = 0.035), but total cholesterol, HDL and LDL levels were not significantly changed by the consumption of the carotenoid mixture. Conclusions: Consumption of the natural carotenoid mixture lowered the increase in oxidative stress induced by the fish oil as assessed by ex vivo oxidative stability of LDL and DNA degradation product in urine. The carotenoid mixture also enhanced the plasma triglyceride-lowering effect of the fish oil.
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Fecal water (FW) has been shown to exert, in cultured cells, cytotoxic and genotoxic effects that have implications for colorectal cancer (CRC) risk. We have investigated a further biological activity of FW, namely, the ability to affect gap junctions in CACO2 cell monolayers as an index of mucosal barrier function, which is known to be disrupted in cancer. FW samples fi-om healthy, free-living, European subjects that were divided into two broad age groups, adult (40 +/- 9.7 yr; n = 53) and elderly (76 +/- 7.5 yr; n = 55) were tested for effects on gap junction using the transepithelial resistance (TER) assay. Overall, treatment of CACO2 cells with FW samples fi-om adults increased TER (+ 4 %), whereas FW from elderly subjects decreased TER (-5%); the difference between the two groups was significant (P < 0.05). We also measured several components of FW potentially associated with modulation of TER, namely, short-chain fatty acid (SCFA) and ammonia. SCFAs (propionic, acetic, and n-butyric) were significantly lower in the elderly population (-30%, -35%, and -21%, respectively, all P pound 0.01). We consider that FW modulation of in vitro epithelial barrier function is a potentially useful noninvasive biomarker, but it requires further validation to establish its relationship to CRC risk.
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Background:Excessive energy intake and obesity lead to the metabolic syndrome (MetS). Dietary saturated fatty acids (SFAs) may be particularly detrimental on insulin sensitivity (SI) and on other components of the MetS. Objective:This study determined the relative efficacy of reducing dietary SFA, by isoenergetic alteration of the quality and quantity of dietary fat, on risk factors associated with MetS. Design:A free-living, single-blinded dietary intervention study. Subjects and Methods:MetS subjects (n=417) from eight European countries completed the randomized dietary intervention study with four isoenergetic diets distinct in fat quantity and quality: high-SFA; high-monounsaturated fatty acids and two low-fat, high-complex carbohydrate (LFHCC) diets, supplemented with long chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs) (1.2 g per day) or placebo for 12 weeks. SI estimated from an intravenous glucose tolerance test (IVGTT) was the primary outcome measure. Lipid and inflammatory markers associated with MetS were also determined. Results:In weight-stable subjects, reducing dietary SFA intake had no effect on SI, total and low-density lipoprotein cholesterol concentration, inflammation or blood pressure in the entire cohort. The LFHCC n-3 PUFA diet reduced plasma triacylglycerol (TAG) and non-esterified fatty acid concentrations (P<0.01), particularly in men. Conclusion:There was no effect of reducing SFA on SI in weight-stable obese MetS subjects. LC n-3 PUFA supplementation, in association with a low-fat diet, improved TAG-related MetS risk profiles.
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As an obligatory parasite of humans, the body louse (Pediculus humanus humanus) is an important vector for human diseases, including epidemic typhus, relapsing fever, and trench fever. Here, we present genome sequences of the body louse and its primary bacterial endosymbiont Candidatus Riesia pediculicola. The body louse has the smallest known insect genome, spanning 108 Mb. Despite its status as an obligate parasite, it retains a remarkably complete basal insect repertoire of 10,773 protein-coding genes and 57 microRNAs. Representing hemimetabolous insects, the genome of the body louse thus provides a reference for studies of holometabolous insects. Compared with other insect genomes, the body louse genome contains significantly fewer genes associated with environmental sensing and response, including odorant and gustatory receptors and detoxifying enzymes. The unique architecture of the 18 minicircular mitochondrial chromosomes of the body louse may be linked to the loss of the gene encoding the mitochondrial single-stranded DNA binding protein. The genome of the obligatory louse endosymbiont Candidatus Riesia pediculicola encodes less than 600 genes on a short, linear chromosome and a circular plasmid. The plasmid harbors a unique arrangement of genes required for the synthesis of pantothenate, an essential vitamin deficient in the louse diet. The human body louse, its primary endosymbiont, and the bacterial pathogens that it vectors all possess genomes reduced in size compared with their free-living close relatives. Thus, the body louse genome project offers unique information and tools to use in advancing understanding of coevolution among vectors, symbionts, and pathogens.
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Objective: To examine the effects of the consumption of fish oils on the gene expression of lipoprotein lipase (LPL, EC 3.1.1.34) in human adipose tissue. In order to measure LPL mRNA in adipose tissue samples obtained by needle biopsy from human volunteers a competitive, reverse transcriptase PCR (RT-PCR) protocol was developed. Design: A randomised controlled, single blind cross over dietary study which compared the effects of a low level n-3 polyunsaturated fatty acids (PUFA) using normal foods enriched with eicosapentaenoic (EPA) and docosahexaenoic (DHA) (test diet), with non-enriched but otherwise identical foods (control). The diets were consumed for a period of 22 d with a wash out period of 5 months between the diets. Setting: Free-living individuals associated with the University of Surrey. Subjects: Six male subjects with a mean (±sd) age of 51.2±3.6 y were recruited. Major Outcome Measures: Pre-and postprandial blood samples were taken for the measurement of triacylglycerol (TAG), postheparin LPL activity and adipose tissue samples for the measurement of LPL mRNA levels. Results: Mean LPL expression values were 4.12´105 molecules of LPL mRNA per ng total RNA on the control diet and 4.60´105 molecules of LPL mRNA per ng total RNA on the n-3 PUFA enriched (test) diet. There was no significant difference between the levels of LPL expression following each diet, consistent with the lack of change in TAG levels in response to increased dietary n-3 PUFA intake. However, the change in LPL expression (Test-Control diet) correlated significantly with the change in fasting TAG levels (P=0.03, R=-0.87 and R2=0.75) and with the total area under the TAG-time response curve (P=0.003, R=-0.96 and R2=0.92) in individuals. Conclusions: These findings, although based on a small number of subjects, suggest that LPL expression may be a determinant of plasma TAG levels. The development of this methodology should allow further elucidation of the effects of dietary manipulation and disease processes on lipid clearance and regulation in human subjects.
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OBJECTIVE: To determine the effect of altering meal frequency on postprandial lipaemia and associated parameters. DESIGN: A randomized open cross over study to examine the programming effects of altering meal frequency. A standard test meal was given on three occasions following: (i) the normal diet; (ii) a period of two weeks on a nibbling and (iii) a period of two weeks on a gorging diet. SETTING: Free living subjects associated with the University of Surrey. SUBJECTS: Eleven female volunteers (age 22 +/- 0.89 y) were recruited. INTERVENTIONS: The subjects were requested to consume the same foods on either a nibbling diet (12 meals per day) or a gorging diet (three meals per day) for a period of two weeks. The standard test meal containing 80 g fat, 63 g carbohydrate and 20 g protein was administered on the day prior to the dietary intervention and on the day following each period of intervention. MAJOR OUTCOME MEASURES: Fasting and postprandial blood samples were taken for the analysis of plasma triacylglycerol, non-esterified fatty acids, glucose, immunoreactive insulin, glucose-dependent insulinotropic polypeptide levels (GIP) and glucagon-like peptide (GLP-1), fasting total, low density lipoprotein (LDL)- and high density lipoprotein (HDL)-cholesterol concentrations and postheparin lipoprotein lipase (LPL) activity measurements. Plasma paracetamol was measured following administration of a 1.5 g paracetamol load with the meal as an index of gastric emptying. RESULTS: The compliance to the two dietary regimes was high and there were no significant differences between the nutrient intakes on the two intervention diets. There were no significant differences in fasting or postprandial plasma concentrations of triacylglycerol, non-esterified fatty acids, glucose, immunoreactive insulin, GIP and GLP-1 levels, in response to the standard test meal following the nibbling or gorging dietary regimes. There were no significant differences in fasting total or LDL-cholesterol concentrations, or in the 15 min postheparin lipoprotein lipase activity measurements. There was a significant increase in HDL-cholesterol in the subjects following the gorging diet compared to the nibbling diet. DISCUSSION: The results suggest that previous meal frequency for a period of two weeks in young healthy women does not alter the fasting or postprandial lipid or hormonal response to a standard high fat meal. CONCLUSIONS: The findings of this study did not confirm the previous studies which suggested that nibbling is beneficial in reducing the concentrations of lipid and hormones. The rigorous control of diet content and composition in the present study compared with others, suggest reported effects of meal frequency may be due to unintentional alteration in nutrient and energy intake in previous studies.