Cholesterol enhances membrane-damaging properties of model bile by increasing the intervesicular-intermixed micellar concentration of hydrophobic bile salts

Encapsulation of a Desmodium intortum Protein Isolate Pickering Emulsion of β-Carotene: Stability, Bioaccesibility and Cytotoxicity

Owing to their excellent characteristics, Pickering emulsions have been widely used in the development and the application of new carriers for embedding and for delivering active compounds. In this study, β-carotene was successfully encapsulated in a Pickering emulsion stabilized using Desmodium intortum protein isolate (DIPI). The results showed that the encapsulation efficiencies of β-carotene in the control group Tween 20 emulsion (TE) and the DIPI Pickering emulsion (DIPIPE) were 46.7 ± 2.5% and 97.3 ± 0.8%, respectively. After storage for 30 days at 25 °C and 37 °C in a dark environment, approximately 79.4% and 72.1% of β-carotene in DIPIPE were retained. Compared with TE, DIPIPE can improve the stability of β-carotene during storage. In vitro digestion experiments showed that the bioaccessibility rate of β-carotene in DIPIPE was less than that in TE. Cytotoxicity experiments showed that DIPI and β-carotene micelles within a specific concentration range exerted no toxic effects on 3T3 cells. These results indicate that DIPIPE can be used as a good food-grade carrier for embedding and transporting active substances to broaden the application of the protein-based Pickering emulsion system in the development of functional foods.

Cholesterol-bile salt vesicles as potential delivery vehicles for drug and vaccine delivery

The aim of this study was to further investigate the interactions between cholesterol (CH) and mixed bile salts (BS) (sodium cholate and sodium deoxycholate) and their suitability for drug and vaccine delivery. Insulin was used as a model protein to assess the ability of CH:BS vesicles to entrap a therapeutically relevant macromolecule. The association of protein (FITC-insulin) with the CH:BS structure was confirmed with fluorescence microscopy, and the overall morphology of the vesicles was examined with atomic force microscopy (AFM). Results demonstrate that the nature of the vesicles formed between CH and BS is dependent not only on the concentration of BS but also on the increasing CH concentration leading to CH crystal formation.

Physiological responses in swine treated with water containing sodium bicarbonate as a prophylactic for gastric ulcers

Maintenance of gastric pH above 4.0 aids the prevention of bile acid-mediated ulcerative damage to the pars esophageal tissue in pigs. One means of doing so is the addition of buffering compounds, such as sodium bicarbonate, to the water supply; however, any potential physiological effect of buffer consumption has yet to be determined. Experiment 1 tested the acute effects of buffer addition to the water supply on systemic acid-base and electrolyte balance in swine (BW 40.7 +/- 3.0 kg). Consumption of water calculated to a 200 mOsm solution with sodium bicarbonate for 24 h increased (P < 0.05) blood Na+, HCO3(-), and pCO2, although these effects were all within physiologically tolerable levels. Urine pH and Na+ excretion increased (P < 0.001) following the consumption of NaHCO3, with Na+ concentration almost threefold higher in treated pigs compared with controls. Experiment 2 determined the chronic systemic effects of buffer consumption by measuring blood and urine variables, with pigs consuming NaHCO3-treated water throughout. Water consumption increased (P < 0.001) during buffer consumption, although intake levels remained within normal ranges. Blood pH levels were not affected by long-term consumption of dietary buffer; however, blood HCO3(-) (P < 0.05), Na+, and pCO2 (P < 0.01) increased. Urine pH and urine Na+ concentration increased (P < 0.01) in buffer-treated compared with control animals. Results indicate that sodium bicarbonate can safely be added to the water supply for pigs, with no clinically relevant alterations in acid-base balance because the animals readily compensate for buffer intake.

Endoscopy via a gastric cannula to monitor the development of ulcers in the pars esophagea in pigs after consumption of a finely ground feed combined with a period of withholding of feed

OBJECTIVE

To develop an endoscopic technique for use in monitoring devlopment of gastric ulcers via a gastric cannula during withholding of feed and administration of a finely ground diet to pigs.

ANIMALS

6 pigs weighing between 60 and 70 kg.

PROCEDURE

A gastric cannula was surgically inserted adjacent to the pars esophagea in each pig. Pigs were fed a finely ground diet for two 7-day periods that were separated by a 48-hour period during which feed was withheld. Endoscopic examination via the gastric cannula was used to monitor development of ulcers in the pars esophageal region of the pigs during the 48-hour period of feed withhold and subsequent 7-day feeding period. An ulcer score was assigned during each endoscopic examination. A final examination was performed during necropsy and compared with results for the final endoscopic examination.

RESULTS

Consumption of a finely ground diet for 7 days resulted in progressive erosive damage to the pars esophageal region of the stomach. Further significant increases in ulcerative damage were detected after 24 and 48 hours of withholding of feed. Final examination during necropsy did not reveal significant differences from results obtained during the final endoscopic examination.

CONCLUSIONS AND CLINICAL RELEVANCE

Endoscopic examination via a gastric cannula was an effective means of monitoring ulcer development in the pars esophagea of pigs. Feeding a finely ground diet and withholding of feed induced endoscopically observable ulcers in the stratified squamous epithelial region of the stomach. Direct visual examination during necropsy confirmed the accuracy of endoscopic examination.

Simulated intestinal fluid as transport medium in the Caco-2 cell culture model

The Caco-2 model is widely used as a predictive tool for the oral absorption of drug candidates. Presently, transport experiments in the Caco-2 system are usually performed in 'HBSS-like' buffers. In this paper, we investigate the possibility of using simulated intestinal buffers as donor solvent during Caco-2 experiments. Toxicity assessment of these buffers on the monolayer showed that FASSIF was compatible with the Caco-2 model for at least 2 h. On the other hand, FESSIF was toxic to the monolayer. The functionality of the Caco-2 cells was assessed by determination of the transport of model compounds and the metabolic activity of hydrolases in presence of these buffers. Similar P(app) values for the (passive) theophyllin transport as well as for the (active) phenylalanine transport were obtained in TM and FASSIF. It was demonstrated that NaTC (present in FASSIF) had a P-gp inhibitory activity, as inclusion of NaTC in the apical compartment resulted in an increased absorptive and decreased secretory transport of CsA. The activity of the aminopeptidase enzyme was similar in both models. These results suggest that FASSIF can be used as an apical medium in the Caco-2 system. Since bile salts are also present in physiological conditions, the use of FASSIF may increase the relevance for the prediction of oral absorption using Caco-2 experiments.

Combined use of Lactobacillus reuteri and soygerm powder as food supplement

AIMS

The survival of Lactobacillus reuteri when challenged with glycodeoxycholic acid (GDCA), deoxycholic acid (DCA) and soygerm powder was investigated. Moreover, the impact of Lact. reuteri on the bioavailability of isoflavones present in soygerm powder was examined.

METHODS AND RESULTS

The strain experienced a die-off when adding 2 or 3 mmol l-1 bile salts, with more pronounced effects in the case of DCA. By means of a haemolysis test it was shown that toxicity could be due to membrane damage. When 4 g l-1 soygerm powder was added, the Lactobacillus strain survived the bile salt burden better (P < or = 0.05) and the membrane damage in the haemolysis test decreased (P < or = 0.05). The Lact. strain cleaved beta-glycosidic isoflavones during fermentation of milk supplemented with soygerm powder.

CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY

The interactions between the Lactobacillus strain and soygerm powder suggest that combining both in fermented milk can exhibit advantageous probiotic effects. The relevance of the combination of the strain and the soygerm powder should be studied under more relevant physiological conditions.

Mitigation of surfactant erythrocyte toxicity by egg phosphatidylcholine

Polyoxyethylene alkyl ether surfactants have been shown to have excellent penetration enhancing abilities although they are associated with a high level of local toxicity. We have compared the toxicity of a range of polyoxyethylene alkyl ethers (Brij 96, Brij 76, Brij 56, 10 lauryl ether and 9 lauryl ether) to an anionic surfactant (sodium dodecyl sulphate (SDS)), an ampholytic surfactant (lysophosphatidylcholine) and a cationic surfactant (tetradecyltrimethylammonium bromide (TTAB)), in the presence and absence of egg phosphatidylcholine. The toxicity of the surfactants or phospholipid/surfactant mixtures was assessed by measuring haemolytic activity. The test samples were incubated with a suspension of red blood cells for 30 min and Drabkin's reagent was used to indicate the amount of haemoglobin released. All of the polyoxyethylene alkyl ethers, SDS, TTAB and lysophosphatidylcholine exhibited haemolytic activity at concentrations between 0.10 and 0.25 mM. The addition of egg phosphatidylcholine reduced the toxicity for all of the surfactants, with the toxicity of Brij 96 being mitigated to a greater extent than the toxicity of the other polyoxyethylene surfactants examined. The rate of haemolysis induced by Brij 96 or 10 lauryl ether was also reduced by increasing concentrations of phosphatidylcholine. As the phosphatidylcholine content of a mixed surfactant system comprising egg phosphatidylcholine: Brij 96 was replaced by lysophosphatidylcholine and fatty acid, the haemolytic action of the mixture increased markedly. The results from this study show that the toxicity of surfactants to erythrocytes can be mitigated by the addition of egg phosphatidylcholine. Synthetic surfactants combined with phosphatidylcholine may generate drug delivery systems worthy of more extensive investigation.