Assessment of hepatic function, perfusion and parenchyma attenuation with indocyanine green, ultrasound and computed tomography in a healthy rat model: Preliminary determination of baseline parameters in a healthy liver.

BACKGROUND: Defining reference intervals in experimental animal models plays a crucial role in pre-clinical studies. The hepatic parameters in healthy animals provide useful information about type and extension of hepatic damage. However, in the majority of the cases, to obtain them require an invasive techniques. Our study combines these determinations with dynamic functional test and imaging techniques to implement a non-invasive protocol for liver evaluation. The aim of the study was to determine reference intervals for hepatic function, perfusion and parenchyma attenuation with analytical and biochemical blood parameters, indocyanine green, ultrasound and computed tomography in six healthy SD rats. METHODS: Six males healthy SD rats were followed for 4 weeks. To determine hepatic function, perfusion and parenchyma attenuation analytical and biochemical blood parameters, indocyanine green, ultrasound and computed tomography were studied. Results were expressed as Means ± standard error of mean (SEM). The significance of differences was calculated by using student t-test, p < 0.05 was considered statistically significant. RESULTS: Indocyanine green clearance 5 and 10 minutes after its injection was 80.12% and 96.59%, respectively. Approximate rate of decay during the first 5 minutes after injection was 38% per minute. Hepatic perfusion evaluation with the high-frequency ultrasound was related to cardiovascular hemodynamic and renal perfusion. Portal area, hepatic artery resistance index, hepatic artery and portal peak systolic velocity and average between hepatic artery and porta was 3.41 ± 0.62 mm2, 0.57 ± 0.04 mm2/s, 693.24±102.53 mm2/s, 150.72 ± 17.80 mm2/s and 4.82 ± 0.96 mm2/s, respectively. Heart rate, cardiac output, left renal artery diammetre and renal blood flow were 331.01 ± 22.22 bpm, 75.58 ± 8.72 mL/min, 0.88 ± 0.04 mm2 and 13.65 ± 1.95 mm2/s. CT-scan hepatic average volume for each rat were 21.08±3.32, 17.57±2.76, 14.87±2.83 and 13.67±2.45 cm3 with an average attenuation coefficient of 113.51±18.08, 129,19±7.18, 141,47±1.95 y 151,67±1.2 HU. CONCLUSION: Indocyanine green and high-frequency ultrasound could be used in rats as a suitable marker of liver function. Computed tomography, through the study of raw data, help to characterize liver parenchyma, and could be a potential tool for early detection of liver parenchymal alterations and linear follow-up of patients. Further studies in rats with liver disease are necessary to verify the usefulness of these parameters.

Iron bioavailability of four iron sources used to fortify infant cereals, using anemic weaning pigs as a model.

PURPOSE: Iron (Fe) deficiency anemia in young children is a global health concern which can be reduced by Fe fortification of foods. Cereal is often one of the first foods given to infants, providing adequate quantities of Fe during weaning. In this work, we have compared iron bioavailability and iron status of four iron sources used to fortify infant cereals, employing piglets as an animal model. METHOD: The study was conducted on 36 piglets, 30 of them with induced anemia. From day 28 of life, the weaned piglets were fed with four experimental diets (n = 6) each fortified with 120 mg Fe/kg by ferrous sulfate heptahydrate (FSH), electrolytic iron (EI), ferrous fumarate (FF), or micronized dispersible ferric pyrophosphate (MDFP) for another 21 days. In addition, one group of six anemic piglets fed with the basal diet with no iron added (Control-) and a Control+ group of non-anemic piglets (n = 6) were also studied. Blood indicators of iron status were measured after depletion and during the repletion period. The Fe content in organs, hemoglobin regeneration efficiency, and relative bioavailability (RBV) was also determined. RESULTS: The Fe salts adequately treated anemia in the piglets, allowing the animals to recover from the anemic state, although EI was less efficient with regard to replenishing Fe stores giving lower concentrations of plasma ferritin and iron in the spleen, liver, lung, and kidney. In addition, the RBV of EI was 88.27% with respect to the reference iron salt (FSH). CONCLUSIONS: Ferrous fumarate and MDFP were equally as bioavailable as the reference salt, and were used significantly better than EI in piglets. These results contribute to extend the evidence-based results for recommending the most suitable fortificant for infant cereals.

Physicochemical properties of different thickeners used in infant foods and their relationship with mineral availability during in vitro digestion process.

Locust bean gum (LBG) and modified starches are commonly used as thickeners in food products for infants. However, there is no consensus on their possible effects on infant nutrition, especially on mineral availability. The aim of the present work was to characterize the effect of LBG, cross-linked, hydroxypropylated maize starch (Mhdp) and pre-gelatinized rice starch (gRS) on Ca, Fe and Zn availability during a gastric and intestinal in vitro digestion assay in relation to their physicochemical properties in solution (apparent viscosity, solubility, molar mass (M) and conformational properties) through the simulated digestion process. LBG gave the highest decrease in Ca and Fe gastric (17.96% and 17.6% respectively) and intestinal (19.5% and 13.5%) solubility with respect to the reference without thickeners. Ca (11.1%±1.1), Fe (2.77%±0.3) and Zn (7.78%±0.6) dialyzability was also lower than for the reference (23.4%±2.9; 19.65%±3.53 and 27.74%±3.3 respectively). LBG solubility remained stable during gastric digestion, decreasing significantly from a range of 65-69% to 61.1% after intestinal digestion. LBG viscosity remained stable during the digestion process, being these findings attributable to its resistance to enzymes. On the other hand, the addition to Mhdp or gRS slightly affected Ca and Fe solubility or Ca dialyzability, decreasing after gastric digestion and then increasing after intestinal digestion with respect to the reference. These results correlated to the changes in their viscosity enhancing properties, which increased during gastric digestion and decreased after intestinal digestion, being attributable to their digestion by pancreatic enzymes. Gastric digestion resulted in an increase in M for the modified starches (more pronounced for gRS). The increase in mineral solubility and dialyzability after intestinal digestion with respect to the gastric stage was explained by the degradation of starches by intestinal enzymes, which resulted in a decrease in apparent shear viscosity (from 1.2 to 1Pas, measured in a shear rate range 0.00-50s-1) and an increase in solubility (from 3 to 6% to approximately 70%) after intestinal digestion. In conclusion, LBG could be more effective than Mhdp and gRS as thickener, providing higher viscosity and resistance to digestive process. However, its negative effect on mineral solubility and dialyzability should be taken into account. On the contrary, Mhdp and gRS showed to be degraded after intestinal digestion.