54 resultados para Bioavailability


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BACKGROUND: Low iron intake can lead to iron deficiency, which can result in impaired health and iron-deficiency anemia. A mobile phone app, combining successful dietary strategies to increase bioavailable iron with strategies for behavior change, such as goal setting, monitoring, feedback, and resources for knowledge acquisition, was developed with the aim to increase bioavailable iron intake in premenopausal women.

OBJECTIVE: To evaluate the content, usability, and acceptability of a mobile phone app designed to improve intake of bioavailable dietary iron.

METHODS: Women aged 18-50 years with an Android mobile phone were invited to participate. Over a 2-week period women were asked to interact with the app. Following this period, semistructured focus groups with participants were conducted. Focus groups were audio recorded and analyzed via an inductive open-coding method using the qualitative analysis software NVivo 10. Themes were identified and frequency of code occurrence was calculated.

RESULTS: Four focus groups (n=26) were conducted (age range 19-36 years, mean 24.7, SD 5.2). Two themes about the app's functionality were identified (frequency of occurrence in brackets): interface and design (134) and usability (86). Four themes about the app's components were identified: goal tracker (121), facts (78), photo diary (40), and games (46). A number of suggestions to improve the interface and design of the app were provided and will inform the ongoing development of the app.

CONCLUSIONS: This research indicates that participants are interested in iron and their health and are willing to use an app utilizing behavior change strategies to increase intake of bioavailable iron. The inclusion of information about the link between diet and health, monitoring and tracking of the achievement of dietary goals, and weekly reviews of goals were also seen as valuable components of the app and should be considered in mobile health apps aimed at adult women.

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It has been well documented that the ingestion of omega-3 polyunsaturated fatty acids (n-3 LC-PUFA) can improve health. However, little scientific attention has been paid on the actual bioavailability of n-3 LC-PUFA. In this thesis, several nutritional questions related to bioavailability of n-3 LC-PUFA have been answered.

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Metals are essential for the normal functioning of living organisms. Their uses in biological systems are varied, but are frequently associated with sites of critical protein function, such as zinc finger motifs and electron or oxygen carriers. These functions only require essential metals in minute amounts, hence they are termed trace metals. Other metals are, however, less beneficial, owing to their ability to promote a wide variety of eleterious health effects, including cancer. Metals such as arsenic, for example, an produce a variety of diseases ranging from keratosis of the palms and feet to cancers in multiple target organs. The nature and type of metal-induced pathologies appear to be dependent on the concentration, speciation, and length of exposure. Unfortunately, human contact with metals is an inescapable consequence of human life, with exposures occurring from both occupational and environmental sources. A uniform mechanism of action for all harmful metals is unlikely, if not implausible, given the diverse chemical properties of each metal. In this chapter we will review the mechanisms of carcinogenesis of arsenic, cadmium, chromium, and nickel, the four known carcinogenic metals that are best understood. The key areas of speciation, bioavailability, and mechanisms of action are discussed with particular reference to the role of metals in alteration of gene expression and maintenance of genomic integrity.

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The extracts from the roots of Salvia miltiorrhiza Bunge (Danshen) are widely and traditionally used in the treatment of angina pectoris, acute myocardial infarct, hyperlipidemia and stroke in China and other Asian countries. In this study, we have investigated the role of P-glycoprotein (P-gp) in the intestinal absorption of tanshinone IIA (TSA), a major active constituent of Danshen, using several in vitro and in vivo models. The oral bioavailability of TSA was about 2.9

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There is an increasing use of herbal medicines worldwide, and the extracts from the root of Salvia miltiorrhiza are widely used in the treatment of angina and stroke. In this study, we investigated the mechanism for the intestinal absorption of tanshinone IIB (TSB), a major constituent of S. miltiorrhiza. The oral bioavailability of TSB was about 3% in rats with less proportional increase in its maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) with increasing dosage. The time to Cmax (Tmax) was prolonged at higher oral dosage. In a single pass rat intestinal perfusion model, the permeability coefficients (Papp) based on TSB disappearance from the lumen (Plumen) were 6.2- to 7.2-fold higher (p < 0.01) than those based on drug appearance in mesenteric venous blood (Pblood). The uptake and efflux of TSB in Caco-2 cells were also significantly altered in the presence of an inhibitor for P-glycoprotein (PgP) or for multi-drug resistance associated protein (MRP1/2). TSB transport from the apical (AP) to basolateral (BL) side in Caco-2 monolayers was 3.3- to 5.7-fold lower than that from BL to AP side, but this polarized transport was attenuated by co-incubation of PgP or MRP1/2 inhibitors. The Papp values of TSB in the BL-AP direction were significantly higher in MDCKII cells over-expressing MDR1 or MRP1, but not in cells over-expressing MRP2-5, as compared with the wild-type cells. The plasma AUC0-24hr in mdr1a and mrp1 gene-deficient mice was 10.2- to 1.7-fold higher than that in the wild-type mice. Furthermore, TSB significantly inhibited the uptake of digoxin and vinblastine in membrane vesicles containing PgP or MRP1. TSB also moderately stimulated PgP ATPase activity. Taken collectively, our findings indicate that TSB is a substrate for PgP and MRP1 and that drug resistance to TSB therapy and drug interactions may occur through PgP and MRP1 modulation.

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The nature of intestinal absorption of most herbal medicine is unknown. Cryptotanshinone (CTS) is the principal active constituent of the widely used cardiovascular herb Salvia miltiorrhiza (Danshen). We investigated the oral bioavailability of CTS in rats and the mechanism for its intestinal absorption using several in vitro and in vivo models:1) Caco-2 cell monolayers; 2) monolayers of MDCKII cells overexpressing P-glycoprotein
(PgP); and 3) single-pass rat intestinal perfusion with mesenteric vein cannulation. The systemic bioavailabilities of CTS after oral and intraperitoneal administration at 100 mg/kg were 2.05 and 10.60%, respectively. In the perfused rat intestinal model, permeability coefficients based on CTS disappearance from the luminal perfusate (Plumen) were 6.7- to 10.3-fold higher than permeability coefficients based on drug appearance in venous blood (Pblood). Pblood significantly increased in the presence of the P-gP inhibitor, verapamil. CTS transport across Caco-2 monolayers was pH-, temperature- and ATP-dependent. The transport from the apical (AP) to the basolateral (BL) side was 3- to 9-fold lower than that from the BL to the AP side. Inclusion of verapamil (50 µM) in both AP and BL sides abolished the polarized CTS transport across Caco-2 cells. Moreover, CTS was significantly more permeable in the BL to AP than in the AP to BL direction in MDCKII and MDR1-MDCKII cells. The permeability coefficients in the BL to AP direction were significantly higher in MDCKII cells overexpressing PgP. These findings indicate that CTS is a substrate for PgP that can pump CTS into the luminal side.

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Background Enteral tubes are frequently inserted as part of medical treatment in a wide range of patient situations. Patients with an enteral tube are cared for by nurses in a variety of settings, including general and specialised acute care areas, aged care facilities and at home. Regardless of the setting, nurses have the primary responsibility for administering medication through enteral tubes. Medication administration via an enteral tube is a reasonably common nursing intervention that entails a number of skills, including preparing the medication, verifying the tube position, flushing the tube and assessing for potential complications. If medications are not given effectively through an enteral tube, harmful consequences may result leading to increased morbidity, for example, tube occlusion, diarrhoea and aspiration pneumonia. There are resultant costs for the health-care system related to possible increased length of stay and increased use of equipment. Presently what is considered to be best practice to give medications through enteral tubes is unknown.

Objectives The objective of this systematic review was to determine the best available evidence on which nursing interventions are effective in minimising the complications associated with the administration of medications via enteral tubes in adults. Nursing interventions and considerations related to medication administration included form of medication, verifying tube placement before administration, methods used to give medication, methods used to flush tubes, maintenance of tube patency and specific practices to prevent possible complications related to the administration of enteral medications.

Search strategy The following databases were searched for literature reported in English only: CINAHL, MEDLINE, The Cochrane Library, Current Contents/All Editions, EMBASE, Australasian Medical Index and PsychINFO. There was no date restriction applied. In addition, the reference lists of all included studies were scrutinised for other potentially relevant studies.

Selection criteria Systematic reviews of randomised controlled trials (RCTs) and RCTs that compared the effectiveness of nursing interventions and considerations used in the administration of medications via enteral tubes. Other research methods, such as non-randomised controlled trials, longitudinal studies, cohort and case control studies, were also included. Exclusion criteria included studies investigating drug–nutrient interactions or the bioavailability of specific medications.

Data collection and analysis Initial consideration of potential relevance to the review was carried out by the primary author (NP). Two reviewers independently assessed study eligibility for inclusion. A meta-analysis could not be undertaken, as there were no comparable RCTs identified. All data were presented in a narrative summary.

Results There is very limited evidence regarding the effectiveness of nursing interventions in minimising the complications associated with enteral tube medication administration in adults. The review highlights a lack of high quality research on many important nursing issues relating to enteral medication administration. There is huge scope for further research. Some of the evidence that was identified included that nurses should consider the use of liquid form medications as there may be fewer tube occlusions than with solid forms in nasoenteral tubes and silicone percutaneous endoscopic gastronomy tubes. Nurses may need to consider the sorbitol content of some liquid medications, for example, elixirs, as diarrhoea has been attributed to the sorbitol content of the elixir, not the drug itself. In addition, the use of 30 mL of water for irrigation when administering medications or flushing small-diameter nasoenteral tubes may reduce the number of tube occlusions.

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Objective: We hypothesized that a dietary combination of soy with either a probiotic (yoghurt) or a prebiotic (resistant starch) would result in enhanced lipid-lowering effects compared with a control soy diet, possibly via improvements in isoflavone bioavailability.

Subjects: Mildly hypercholesterolaemic subjects (men and post-menopausal women) older than 45 years were recruited via the local media. Thirty-six subjects commenced the study; five withdrew.

Results: Soy+probiotic significantly decreased total cholesterol (4.72.0%; P=0.038) and soy+prebiotic significantly decreased total and low-density lipoprotein cholesterol (5.51.6%; P=0.003 and 7.32.2%; P=0.005, respectively). The bioavailabilities of daidzein, genistein or equol were not affected by probiotic or prebiotic consumption or associated with lipid changes.

Conclusion: Dietary combination of soy with either a probiotic or a prebiotic resulted in significant lipid lowering, not related to isoflavone bioavailability.

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Omega-3 oil from fish can be stabilised against oxidation using a variety of microencapsulation technologies. Complex coacervation has been used and found to be commercially useful for fortifying foods and beverages with long-chain omega-3 containing oils. Here we report a comparative human bioavailability study of microencapsulated omega-3 fish oil and standard fish-oil soft-gel capsules. Phospholipid levels of long-chain omega-3 fatty acids increased equivalently in both subjects groups. Also, triacylglycerol levels were reduced similarly in both groups. These results indicate that omega-3 fatty acids have equivalent bioavailability when delivered as microencapsulated complex coacervates or as soft-gel capsules.

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The Pieman River catchment has seen continuous mining of economic deposits of gold, silver, lead, copper, zinc and tin since the 1870’s. Tributaries of this river which receive mining effluent, either directly or from acid mine drainage (AMID), have total metal concentrations considerably above background levels and are of regulatory concern. The lower Pieman River is however classified as a State Reserve in which recreational fishing and tourism are the major activities. It is therefore important that water entering the lower Pieman River from upstream hydroelectric impoundments is of high quality. Metals in natural waters exist in a variety of dissolved, colloidal and particulate forms. The bioavailability and hence toxicity of heavy metal pollutants is very dependant on their physico form. Knowledge of the speciation of a metal in natural aquatic environments is therefore necessary for understanding its geochemical behaviour and biological availability. Complexation of metal ions by natural ligands in aquatic systems is believed to play a significant role in controlling their chemical speciation. This study has investigated temporal and spatial variation in complexation of metal ions in the Pieman River. The influence of pH, temperature, organic matter, salinity, ionic strength and time has been investigated in a series of field studies and in laboratory-based experiments which simulated natural and anthropogenic disturbances. Labile metals were measured using two techniques in various freshwater and estuarine environments. Diffusive gradients in thin-films (DGT) allowed in situ measurement of solution speciation whilst differential pulse anodic stripping voltammetry (DPASV) was used to measure labile metal species in water samples collected from the catchment. Organic complexation was found to be a significant regulating mechanism for copper speciation and the copper-binding ligand concentration usually exceeded the total copper concentration in the river water. Complexation was highly dependent on pH and at the river-seawater interface was also regulated by salinity, probably as a result of competitive complexation by major ions in seawater (eg. Ca 2+ ions). Zinc complexation was also evident, however total zinc concentrations in the water column often far exceeded the potential binding capacity of available ligands. In addition to organic complexation, Zn speciation may also be associated with adsorption by flocculated or resuspended colloidal Mn and/or Fe oxyhydroxides. Metal ion complexation and hence speciation was found to be highly variable within the Pieman River catchment. This presents major difficulties for environmental managers, as it is therefore not possible to make catchment-wide assumptions about the bioavailability of these metals. These results emphasise the importance of site-specific sampling protocols and speciation testing, ideally incorporating continuous, in situ monitoring.

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The Mediterranean diet is associated with a lower incidence of atherosclerosis, cardiovascular disease, neurodegenerative diseases and certain types of cancer. The apparent health benefits have been partially ascribed to the dietary consumption of virgin olive oil by Mediterranean populations. Much research has focused on the biologically active phenolic compounds naturally present in virgin olive oils to aid in explaining reduced mortality and morbidity experienced by people consuming a traditional Mediterranean diet. Studies (human, animal, in vivo and in vitro) have demonstrated that olive oil phenolic compounds have positive effects on certain physiological parameters, such as plasma lipoproteins, oxidative damage, inflammatory markers, platelet and cellular function, antimicrobial activity and bone health. This paper summarizes current knowledge on the bioavailability and biological activities of olive oil phenolic compounds.

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Pharmacokinetic studies have become an integral part of modern drug development, but these studies are not regulatory needs for herbal remedies. This paper updates our current knowledge on the disposition pathways and pharmacokinetic properties of commonly used herbal medicines in humans. To retrieve relevant data, the authors have searched through computer-based literatures by full text search in Medline (via Pubmed), ScienceDirect, Current Contents Connect (ISI), Cochrance Library, CINAHL (EBSCO), CrossRef Search and Embase (all from inception to May 2010). Many herbal compounds undergo Phase I and/or Phase II metabolism in vivo, with cytochrome P450s (CYPs) and uridine diphosphate glucuronosyltransferases (UGTs) playing a major role. Some herbal ingredients are substrates of P-glycoprotein (P-gp) which is highly expressed in the intestine, liver, brain and kidney. As such, the activities of these drug metabolizing enzymes and drug transporters are determining factors for the in vivo bioavailability, disposition and distribution of herbal remedies. There are increasing pharmacokinetic studies of herbal remedies, but these studies are mainly focused on a small number of herbal remedies including St John's wort, milk thistle, sculcap, curcumin, echinacea, ginseng, ginkgo, and ginger. The pharmacokinetic data of a small number of purified herbal ingredients, including anthocyanins, berberine, catechins, curcumin, lutein and quercetin, are available. For the majority of herbal remedies used in folk medicines, data on their disposition and biological fate in humans are lacking or in paucity. For a herbal medicine, the pharmacological effect is achieved when the bioactive agents or the metabolites reach and sustain proper levels at their sites of action. Both the dose levels and fates of active components in the body govern their target-site concentrations after administration of an herbal remedy. In this regard, a safe and optimal use of herbal medicines requires a full understanding of their pharmacokinetic profiles. To optimize the use of herbal remedies, further clinical studies to explore their biological fate including the disposition pathways and kinetics in the human body are certainly needed.

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Polycyclic aromatic hydrocarbons (PAHs) are toxic environmental pollutants that are known or suspected carcinogens or mutagens. Bioremediation has been used as a general way to eliminate them from the contaminated sites or aquifers, but their biodegradation is rather limited due to their low bioavailability because of their sparingly soluble nature. Surfactant-mediated biodegradation is a promising alternative. The presence of surfactants can increase the solubility of PAHs and hence potentially increase their bioavailability. However, inconclusive results have been reported on the effects of surfactant on the biodegradation of PAHs. In this work, surfactant-mediated biodegradation of PAHs is reviewed.

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Biodegradation of poorly soluble polycyclic aromatic hydrocarbons (PAHs) has been a challenge in bioremediation. In recent years, surfactant-enhanced bioremediation of PAH contaminants has attracted great attention in research. In this study, biodegradation of phenanthrene as a model PAHs solubilized in saline micellar solutions of a biodegradable commercial alcohol ethoxylate nonionic surfactant was investigated. The critical micelle concentration (CMC) of the surfactant and its solubilization capacity for phenanthrene were examined in an artificial saline water medium, and a type of marine bacteria, Neptunomonas naphthovorans, was studied for the biodegradation of phenanthrene solubilized in the surfactant micellar solutions of the saline medium. It is found that the solubility of phenanthrene in the surfactant micellar solutions increased linearly with the surfactant concentrations, but, at a fixed phenanthrene concentration, the biodegradability of phenanthrene in the micellar solutions decreased with the increase of the surfactant concentrations. This was attributed to the reduced bioavailability of phenanthrene, due to its increased solubilization extent in the micellar phase and possibly lowered mass transfer rate from the micellar phase into the aqueous phase or into the bacterial cells. In addition, an inhibitory effect of the surfactant on the bacterial growth at high surfactant concentrations may also play a role. It is concluded that the surfactant largely enhanced the solubilization of phenanthrene in the saline water medium, but excess existence of the surfactant in the medium should be minimized or avoided for the biodegradation of phenanthrene by Neptunomonas naphthovorans.

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The Mediterranean diet is associated with a lower incidence of chronic degenerative diseases and higher life expectancy. These health benefits have been partially attributed to the dietary consumption of extra virgin olive oil (EVOO) by Mediterranean populations, and more specifically the phenolic compounds naturally present in EVOO. Studies involving humans and animals (in vivo and in vitro) have demonstrated that olive oil phenolic compounds have potentially beneficial biological effects resulting from their antimicrobial, antioxidant and anti-inflammatory activities. This paper summarizes current knowledge on the biological activities of specific olive oil phenolic compounds together with information on their concentration in EVOO, bioavailability and stability over time.