Biomedical subjects

I López-Aliaga

Publications and source records attributed to I López-Aliaga.

At least 19 recordsLinked to original sources

PubMed2005

Goat milk feeding causes an increase in biliary secretion of cholesterol and a decrease in plasma cholesterol levels in rats.

The hypocholesterolemic effect of goat milk with respect to cow milk observed in a previous study led us to examine the influence of goat and cow milk in the diet on certain aspects of biliary physiology in normal rats. The fat content in all diets was 10% but the lipid quality was varied: the standard diet was based on virgin olive oil, and the other 2 diets included fat obtained from lyophilized cow milk and goat milk. We characterized the bile secretion, including biliary phospholipid, cholesterol, and bile acid outputs, the interrelation between bile acids and bile lipids, and the lithogenic index. The consumption of goat milk in the diet, compared with that of cow milk, caused an increase in the biliary secretion of cholesterol together with a decrease in plasma cholesterol concentration, whereas values for bile phospholipids, biliary acid concentrations, and the lithogenic index remained normal. Moreover, consumption of this type of milk decreased plasma triglyceride concentration and therefore had a positive effect, similar to that of olive oil (standard diet), on the lipid metabolism; hence, it may be recommended for consumption by the general population.

Animal Feed↗

PubMed2000

Beneficial effect of pollen and/or propolis on the metabolism of iron, calcium, phosphorus, and magnesium in rats with nutritional ferropenic anemia.

There has been considerable debate regarding the nutritional benefits of pollen and the propolis produced by bees, although most contributions have lacked scientific soundness. This paper describes the possible beneficial effect of their use in pharmacological products in cases of anemic syndrome. We studied the effect of these two natural products on the digestive utilization of iron, calcium, phosphorus, and magnesium, using control rats and rats with nutritional ferropenic anemia. The addition of these products to the diet produced a positive effect on weight gain; this fact could constitute a scientific basis for the application of pollen and propolis as fortifiers. They improve the digestive utilization of iron and the regeneration efficiency of hemoglobin, especially during recovery from an anemic syndrome. They also have a positive effect on phosphocalcic metabolism and maintain an appropiate level of magnesium metabolism. Furthermore, in iron-deficient rats, these natural products palliate, to a large extent, the adverse effects of iron deficiency on calcium and magnesium metabolism as a result of the improvement in the digestive utilization of these minerals.

Anemia, Iron-Deficiency↗

PubMed1999

The importance of the proportion of heme/nonheme iron in the diet to minimize the interference with calcium, phosphorus, and magnesium metabolism on recovery from nutritional ferropenic anemia.

The digestive utilization of Fe and its nutritive interaction with Ca, P, and Mg were studied in rats with nutritional ferropenic anemia. The diet contained 80% ferric citrate and 20% heme iron (80/20 diet). The weight gain, digestive utilization of Fe, and regeneration efficiency of hemoglobin and seric Fe were higher in iron-deficient rats (ID) fed the 80/20 diet than in iron-deficient rats fed the 50/50 diet (Campos et al., 1996). The phospho-calcic metabolism, which is adversely affected in ferropenic anemia, returned to normal values when iron was added to the diet. The digestive utilization of Mg, which fell with the 50/50 diet (Campos et al., 1996), returned to normal values when the ferropenic anemia was reversed with the 80/20 diet. In a state of iron deficiency, certain parameters related to the glucose and lipid metabolism are affected; the glucose and triglycerides values return to a normal range with the 80/20 diet.

Anemia, Iron-Deficiency↗

PubMed1998

Iron-manganese interactions in the evolution of iron deficiency.

This article examines the evolution of nutritional iron deficiency and the possible interactions with other minerals, such as manganese, in control and iron-deficient rats. The evolution of iron deficiency was studied at 0, 10, 20, 30 and 40 days of providing the animals with an iron-free diet (diet 0). It was found that the critical period in the development of nutritional iron deficiency occurs after 30-40 days without iron, at which moment the organism is unable to maintain hemoglobin levels without endangering the iron-dependent enzymatic groups which, in turn, are essential for life. It was also demonstrated that in a situation of iron deficiency, there occurs a greater absorption of manganese. It should be noted that this greater absorption of manganese is not reflected in the concentration of the mineral in the organs. Therefore, it is evident that the interactions of iron with manganese take place at the digestive level with no apparent consequences being observed at the metabolic level.

Animal Nutritional Physiological Phenomena↗

PubMed1998

Influence of nutritional iron deficiency development on some aspects of iron, copper and zinc metabolism.

This paper examines the development of iron (Fe) deficiency and its possible interactions with trace elements such as zinc (Zn) and copper (Cu) by investigating iron-deficient and control rats. The effects of iron deficiency were studied at day 0, 10, 20, 30 and 40 in rats fed on an iron-free diet (diet ID). It was found that the critical period in the development of nutritional iron deficiency occurs after 30 to 40 days without iron supplementation. At this time the organism is unable to maintain haemoglobin levels without endangering the iron-dependent enzymatic groups which are essential for life. It was also demonstrated that in a situation of iron deficiency, there occurs a greater absorption of copper, while that of zinc remains unchanged. As iron deficiency progresses, the levels of copper in the spleen and the sternum increase. It is apparent that iron deficiency provokes more marked alterations in the metabolism of copper than of zinc.

Animal Nutritional Physiological Phenomena↗

PubMed1998

The absorption of iron, calcium, phosphorus, magnesium, copper and zinc in the jejunum-ileum of control and iron-deficient rats.

The effects of iron deficiency on the absorption of different dietary sources of iron were studied, together with the interactions between iron, calcium, phosphorus, magnesium, copper and zinc in the jejunum-ileum of control and iron-deficient rats. In this study, three perfusion solutions containing different iron sources: ferric citrate, haemoglobin, and equal parts of ferric citrate and haemoglobin were used. In addition, the same perfusion solutions were used with and without 2,4-dinitrophenol, an inhibitor of oxidative phosphorylation. Iron absorption in anaemic rats was greater than in the controls, except after perfusion with solutions containing haemoglobin. The absorption of calcium, copper and zinc in iron-deficient animals was not significantly affected, while the absorption of phosphorus and magnesium increased, with respect to animals in the control group. After perfusion with solutions containing haemoglobin, the absorption values of calcium, copper and zinc were lower than after ferric citrate in both groups (control and iron-deficient rats).

2,4-Dinitrophenol↗

PubMed1997

Effect of source of iron on duodenal absorption of iron, calcium, phosphorous, magnesium, copper and zinc in rats with ferropoenic anaemia.

We studied the effects of iron deficiency on the in vivo absorption (by using the intestinal perfusion technique in the duodenum) of different dietary sources of iron (haem, non-haem and equal parts of both forms) and investigated the interactions between iron and calcium, phosphorous, magnesium, copper and zinc in control and iron-deficient rats. Three perfusion solutions containing a different source of iron were used: solution 1, ferric citrate; solution 2, haemoglobin; solution 3, equal parts of ferric citrate and haemoglobin. We also tested the same perfusion solution with 2,4-dinitrophenol (2,4-DNP), an inhibitor or oxidative phosphorylation (solutions 1-I, 2-I and 3-I). In control rats we observed three mechanisms of iron absorption: passive for soluble iron salts, active receptor-mediated for non-haem iron complexes, and active receptor-mediated for haem iron. In anaemic rats iron absorption was greater than in controls, except after perfusion with solution 2 (containing haemoglobin). Absorption increased as a result of both the passive and active, receptor-mediated mechanism for non-haem iron complexes. The active component was influenced by the depletion of haem receptors under severe iron deficiency. The absorption of calcium, copper and zinc in iron-deficient animals was lower than in controls, whereas phosphorus and magnesium absorption were not significantly affected. After perfusion with solution 2 or 3, calcium, copper and zinc absorption were lower than after solution 1. We conclude that ferropoenic anaemia in the rat impairs the absorptive process of those minerals that are absorbed, at the duodenal level mainly via active transport (haem iron, calcium, copper and zinc), but does not affect the active component involved in non-haem iron absorption.

Anemia, Iron-Deficiency↗

PubMed1996

Supplementation of a cereal-milk formula with haem iron palliates the adverse effects of iron deficiency on calcium and magnesium metabolism in rats.

Aside from the well known alteration of Fe status in Fe deficiency, this condition has also a negative effect on the bioavailability of Ca and Mg. We studied the influence of the supplementation of a commercial cereal-milk formula with bovine blood on Fe, Ca, P, and Mg metabolism in control and Fe-deficient rats to investigate whether high Fe levels in diet produce some interactions and the possibility of decreasing these latter by a haem-Fe supplementation. The bioavailability in control and Fe-deficient animals was determined as the apparent digestibility coefficient and hemoglobin regeneration efficiency, both of which are accurate estimations of total Fe utilization. Non-fortified cereal-milk formula decreased the apparent digestibility coefficient of Ca and Mg in Fe-deficient rats; the concentrations of these minerals in liver, femur, and sternum were lower than in control animals. However, when the Fe content of the cereal-milk formula was doubled by supplementation with bovine blood, the adverse effects on the digestive utilization of Ca, and especially of Mg, were palliated, the concentration of these two minerals in the organs investigated increased, and the overall Fe status improved in Fe-deficient rats.

Anemia, Iron-Deficiency↗

PubMed1996

Calcium absorption in rats with distal intestinal resection: influence of type of dietary fat, cholecalciferol and nature of the adaptative response.

The effects of dietary fat and supplementation with cholecalciferol on calcium absorption at different luminal concentrations (2.07 mmol/l and 2.07 mmol/l with 0.5 mmol/l 2,4-dinitrophenol and 8.20 mmol/l) were studied in vivo in the perfused duodenum, residual jejunum and proximal colon of rats with resection of 50% of the distal small intestine, as well as the nature of the adaptative response (passive or active). Changing the source of dietary fat (diet B, containing 1/3 medium chain triglycerides, 1/3 olive oil, 1/3 sunflower oil) increased calcium absorption, preferentially via active transport, in both transected and resected rats. Supplementation of diet B with cholecalciferol further enhanced intestinal calcium absorption, especially in the colon. These results suggest the importance of diet in the adaptive processes and confirm that active mechanisms of transport adapt more readily to intestinal resection than do passive mechanisms.

Adaptation, Physiological↗

PubMed1996

Effects of iron replenishment on iron, calcium, phosphorus and magnesium metabolism in iron-deficient rats.

We investigated the effect of Fe deficiency on the nutritive utilization of Fe, Ca, P and Mg in rats. Aside from the well known depletion of Fe in liver, femur and sternum with low values of Hb, Fe deficiency impaired Ca, P and Mg metabolism at different degrees. Iron deficiency altered Mg absorption, lowered the concentration of Ca in the liver, femur and sternum, raised the concentration of P and Mg in the liver, and decreased P in the femur. The altered status was not completely rectified by iron supplementation as the animals were still slightly anemic at the end of the study. The second purpose of the study was to evaluate the ability of three iron compounds (ferric citrate, ferrous sulfate and ferrous ascorbate) to correct the undesirable effects of Fe deficiency. Ten days after treatment with these diets, Fe-deficient rats still had reduced Mg absorption, especially those fed ferric citrate. The concentrations of hemoglobin approached normal values in all groups; however, serum Fe remained low, indicating that Fe reserves were still depleted. Hepatic and femoral Fe concentrations were also lower in all Fe-deficient groups regardless of the diet given, compared with their respective controls, whereas Fe concentrations in the sternum increased significantly with all three diets, suggesting an increase in erythropoiesis. The concentration of Ca, P and Mg in liver approached normal values, and appeared to normalize in the femur, except that Ca and P concentrations remained low with the citrate diet. In the sternum, a site assumed to have higher requirements for these minerals, the concentrations of Ca, P and Mg also increased. These findings indicate that Fe is involved in the bone mineralization, and that in physiological terms, Fe interacts favorably with Ca, P and Mg metabolism, since Fe deficiency altered the status of these metals. These findings also suggest that ferrous ascorbate and ferrous sulfate were more effectively absorbed than was ferric citrate.

Analysis of Variance↗

PubMed1995

Effects of intestinal resection, cholecalciferol and ascorbic acid on iron metabolism in rats.

The effect of dietary supplementation with ascorbic acid or cholecalciferol on Fe utilization was studied using the metabolic balance technique, in rats in which 50% of the distal small intestine was removed, or in which the mid small intestine was transected and reanastomosed (controls). Three different diets were used. The first (basal diet) contained (g/kg dry wt): protein (casein + 50 mg D,L-methionine/g) 120 and fat (medium-chain triacylglycerols, olive oil and sunflower oil, in equal parts) 40. The other diets were obtained by adding ascorbic acid (150 mg/kg diet) or cholecalciferol (0.4 mg/kg diet) to the basal diet. Apparent digestibility coefficient (ADC) and Fe retention were significantly lower in resected animals than in their respective control groups (transected rats). However, the addition of ascorbic acid or cholecalciferol to the basal diet increased the ADC and Fe retention in both transected and resected rats. Five weeks after surgery, resection also resulted in a reduced concentration of Fe in the sternum, but did not reduce the concentration of haemoglobin or serum Fe total Fe-binding capacity or the concentration of Fe in liver, testes, femur or muscle (longissimus dorsi). Supplementation with ascorbic acid increased serum Fe concentration, while the concentration of Fe in muscle was reduced by supplementation with both ascorbic acid and cholecalciferol. Neither supplementation had any effect on the Fe concentration in other tissues, on haemoglobin concentration or plasma total Fe-binding capacity. Thus, supplementation with ascorbic acid or with cholecalciferol increased Fe absorption and reduced the concentration of Fe in muscle.

Animals↗

PubMed1995

Copper malabsorption after intestinal resection in rats. Effects of cholecalciferol and ascorbic acid.

Dietary modifications can partly compensate for the alterations in copper homeostasis caused by distal intestinal resection, by improving biliary function. We studied the effects of resecting 50% of the distal small intestine (DSI) on copper status in rats fed three semisynthetic diets (basal diet, and basal diet with cholecalciferol or ascorbic acid). Intestinal resection significantly decreased the digestive (apparent digestibility coefficient; ADC) and metabolic utilization (balance) of copper 1 month after surgery. However, the supplementation of the basal diet with cholecalciferol attenuated the negative impact of surgery, leading to small differences in Cu ADC and Cu balance between transected and resected rats. Ascorbic acid also enhanced copper retention. Copper status was not as markedly affected by intestinal resection as digestive utilization 1 month after the operation. The beneficial effects of cholecalciferol and ascorbic acid at the digestive and metabolic levels suggest ways to lessen the impact of intestinal resection, and to avoid possible long-term postabsorptive alterations in copper distribution.

Animals↗

PubMed1994

Effect of intestinal resection, type of dietary fat and time on biliary lipid secretion in rats.

The effects of time and the type of dietary fat on biliary physiology in rats with 50% resection of the distal small intestine were investigated. The effects of ursodeoxycholic acid as an exogenous source of bile acid added to the diet were also studied. The fat composition of all diets was the same in quantitative terms (4%), and differed only in the type of lipid supplied: olive oil (diet A) or one-third medium chain triglycerides, one-third sunflower seed oil and one-third olive oil (diet B). In resected rats given diet A for 1 or 3 months, there was a decrease in biliary secretion of cholesterol and phospholipids, and in the lithogenic index, with respect to the control group. Resected rats fed diet B for 1 or 3 months showed increases in biliary secretion of cholesterol and phospholipids, and in the lithogenic index, in comparison with resected rats fed diet A. The addition of ursodeoxycholic acid to diet B led to the decoupling of bile acid and bile lipid secretion.

Animals↗

PubMed1994

Influence of dietary fat components and intestinal resection on iron, zinc and copper metabolism in rats.

The effect of resecting 50% of the distal small intestine (DSI) on iron, zinc and copper nutritive utilization was studied in rats fed two different types of diet: a standard diet containing 4% olive oil (A) and a diet containing different sources of fat (1/3 olive oil, 1/3 sunflower oil and 1/3 medium chain triglycerides) (B). One month and 7 days after surgery, intestinal resection led to a deterioration in digestive (ADC) and metabolic (balance) utilization of iron, zinc and copper. To assess trace metal postresectional homeostasis, we also measured these mineral concentrations in whole blood, plasma and several organs (liver, femur, sternum, longissimus dorsi muscle and testes). Our findings showed no significant differences in iron, zinc and copper concentrations between the organs, suggesting that the observed decrease in digestive and metabolic efficiency of these minerals was not markedly reflected at the postabsorptive level, since the distribution of the trace elements in the whole organism remained unchanged. We conclude that one month and 7 days after this surgical intervention, adaptive mechanisms are well developed in resected rats fed a diet with an adequate mineral supplement.

Animals↗

PubMed1991

Influence of dietary fat on nutritive utilization of protein in intestinally resected rats.

The effects of different types of dietary fat on the digestive and metabolic utilization of protein were studied in rats with 50% resection of the distal small intestine and in sham-operated controls one month after surgery. The digestive utilization of protein was not significantly affected in intact animals when olive oil was replaced by butter as the dietary source of fat. In resected rats given either type of diet the apparent digestibility coefficient of protein declined significantly in comparison to intact controls. Intestinal resection decreased the retention of nitrogen significantly in rats given olive oil. The replacement of 2/3 of the dietary supply of olive oil with 1/3 medium chain triglycerides and 1/3 sunflower seed oil improved the metabolic utilization of protein in comparison to resected rats fed olive oil or butter as the only source of dietary fat. However, the addition of ursodeoxycholic acid to the diet containing equal parts of olive oil, medium chain triglycerides and sunflower seed oil failed to improve the metabolic utilization of protein in comparison to that seen in rats given olive oil only. Serum concentrations of total protein, urea and creatinine, albeit with slight changes in the first, remained within normal limits. Despite the lower retention of nitrogen in resected rats, these animals maintained homeostasis without resorting to muscular protein.

Animals↗

PubMed1991

Influence of ileal resection, type of diet and ursodeoxycholic acid on biliary secretion in rats.

We studied the effects of the type of dietary fat and of ursodeoxycholic acid, an exogenous bile acid added to the diet, on bile physiology in rats with 50% resection of the distal small intestine. The amount of fat was the same (4%) in all diets assayed, which differed only in the type of fat, (olive oil in diet A, and 1/3 medium-chain triglycerides, 1/3 sunflower oil and 1/3 olive oil in diet B). The removal of 50% of the distal small intestine raised the de novo hepatic synthesis of bile acids with respect to controls, regardless of whether diet A or diet B was given. The addition to diet B of ursodeoxycholic acid decreased bile flow and osmotic activity of bile acid in resected rats and raised bile acid-independent bile flow in comparison to resected rats given diet B without ursodeoxycholic acid.

Animals↗

PubMed1991

Influence of time, type of diet and ursodeoxycholic acid on biliary secretion in rats with intestinal resection.

The effects of time and the type of dietary fat on biliary physiology in rats with 50% resection of the distal small intestine was investigated. The effects of ursodeoxycholic acid as an exogenous source in bile acid added to the diet were also studied. The fat composition of all diets was the same in quantitative terms (4%), and differed only in the type of lipid supplied: olive oil (diet A) or 1/3 medium chain triglycerides, 1/3 sunflower seed oil and 1/3 olive oil (diet B). Three months after intestinal resection, neither group of resected rats showed significant changes in bile flow or bile acid output in comparison to controls, whereas the slope of the regression line was notably increased, indicating that enterohepatic circulation failed to adapt to the different dietary fats during recovery from intestinal resection. The addition of ursodeoxycholic acid to diet B significantly raised bile acid flow and output in comparison to controls, as a result of the recovery of enterohepatic circulation. This was reflected in the lower slope of the regression line, thus suggesting that de novo synthesis in resected animals was less intensely stimulated.

Animals↗

PubMed1991

A comparative study of electrolyte and water transport in the rabbit ileum and colon in vitro and in vivo: influence of D-glucose.

The influence of D-glucose on electrolyte and water transport in the distal ileum and proximal colon of the rabbit in vitro and in vivo has been studied. The magnitude of electrolyte and water transport was found to differ in vitro and in vivo. The replacement of mannitol by D-glucose in the intestinal lumen had no effect on ileal and colon transport of the ions studied, i.e., movement of the ions was independent of the supply of exogenous glucose. The distal ileum and the proximal colon of the rabbit in vivo showed a net secretion of bicarbonate, aimed at neutralizing the cecal contents.

Animals↗