Biomedical subjects

M L Failla

Publications and source records attributed to M L Failla.

At least 37 records · Page 2Linked to original sources

PubMed1995

Chronic intake of a marginally low copper diet impairs in vitro activities of lymphocytes and neutrophils from male rats despite minimal impact on conventional indicators of copper status.

We investigated the impact of chronic intake of a diet marginally low in Cu on traditional indicators of Cu status and in vitro activities of splenic mononuclear cells and neutrophils. Pregnant Sprague-Dawley rats were fed diets containing either 2.8 (LCu) or 6.7 [adequate (ACu)]mg Cu/kg from midgestation through lactation. Weaned male and female offspring were fed the same diets as their dams until 6 months of age. Dietary Cu level did not alter growth, heart weight, the concentrations of Cu or the activities of cuproenzymes in serum and most tissues. In contrast, splenic mononuclear cells (MNC) from males, but not females, fed the LCu diet were less responsive to in vitro mitogenic activation and generated less interleukin-2 bioactivity than cultures prepared from males fed the ACu diet. Repletion with the ACu diet for 2 wk restored in vitro activities of splenic MNC to control levels. The phorbol myristate acetate-induced generation of superoxide anion by elicited neutrophils from male rodents fed the LCu diet was only 60% that of cells from the ACu diet group. Brain Cu in adult rats fed LCu diet was irreversibly decreased compared with those fed ACu diet. These data show that the in vitro activities of T lymphocytes and neutrophils isolated from adult male rats chronically fed a diet marginally low in Cu were significantly suppressed without marked alterations in the traditional indicators of Cu status.

Animals↗

PubMed1995

Reduction of Fe(III) is required for uptake of nonheme iron by Caco-2 cells.

Differentiated cultures of Caco-2 human colonic cells were used to examine the importance of reduction of nonheme ferric iron, Fe(III), for transport across the brush border surface. Cultures accumulated approximately 100 pmol Fe/(h.mg protein) when 10 mumol Fe(III) as the nitrilotriacetic acid complex (1Fe:2NTA) was added to the apical compartment. Ascorbic acid enhanced cellular acquisition of iron in a dose-dependent manner, with a concentration as low as 8 mumol/L ascorbate increasing iron uptake by 50%. Similarly, the rate of iron transport from the apical to the basolateral compartment increased 5.6- and 30-fold when 100 and 1000 mumol/L ascorbic acid, respectively, were present in the apical chamber. Ascorbate-mediated stimulation of iron uptake was temperature dependent and required the reduction of Fe(III) to Fe(II), because it was inhibited by ascorbate oxidase and chelators of Fe(II). Moreover, Caco-2 cells recycled dehydroascorbic acid to ascorbic acid. Ferricyanide and Fe(II) chelators also partially inhibited iron uptake from a medium devoid of ascorbic acid. Intact Caco-2 cells exhibited a ferrireductase activity on the apical surface that accounted for the majority of iron accumulated by cells incubated in the absence of exogenous reductant. These data suggest that reduction of Fe(III) within the lumen or at the cell surface is required for transfer of this essential micronutrient across the intestinal brush border surface.

Ascorbic Acid↗

PubMed1995

Marginal copper-restricted diets produce altered cardiac ultrastructure in the rat.

To determine if chronic ingestion of a diet containing a marginally low level of Cu could cause deleterious alterations in cardiac ultrastructure, male offspring were nursed by dams fed a diet containing either 6.7 or 2.8 mg Cu/kg from midgestation through lactation before weaning to the same diet. Conventional measures of Cu status, including growth, relative heart weight, tissue concentrations of Cu, ceruloplasmin activity, and tissue activity of Cu,Zn-superoxide dismutase (SOD) were similar in both dietary treatment groups at 5.5 months of age. However, significant increases in the number and volume of lipid droplets and an increased incidence of pathological abnormalities in mitochondria and basal laminae were observed in sections of hearts from rats chronically fed the diet containing 2.8 mg/kg Cu. Reduction of the dietary level of Cu from 2.8 to 1.3 mg/kg from 4 to 5.5 months of age caused significant reductions in the concentration of Cu in serum and liver, but Cu content, Cu,Zn-SOD activity, pathological scores, and morphometric parameters in hearts were not modified by the greater restriction of dietary Cu in adult rats. This study suggests that abnormalities in cardiac ultrastructure occurred in rats chronically fed diets marginally low in Cu, despite minimal changes in conventional biochemical indicators of Cu status.

Animals↗

PubMed1995

Ascorbate offsets the inhibitory effect of inositol phosphates on iron uptake and transport by Caco-2 cells.

Differentiated monolayer cultures of Caco-2 human intestinal cells were used as a model to examine interactions between various dietary factors related to the intestinal uptake and absorption of nonheme Fe. Caco-2 cells accumulated 91-98 pmol Fe/mg protein from uptake buffer containing 12 nmol of Fe(III)-nitrilotriacetate during a 1-hr incubation at 37 degrees C. Addition of a 10-fold molar excess of inositol hexaphosphate (IP6) and its lesser phosphorylated derivatives (IP3, IP4, and IP5) decreased cellular uptake and transport of Fe from the lumenal compartment. Addition of ascorbic acid (AA) to the solution containing IPs stimulated Fe uptake and transport in a manner dependent upon the ratio of AA to IP and inversely proportional to the degree of phosphorylation of inositol (i.e., IP3 > IP4 > IP5 > IP6). A mixture of essential amino acids had minimal impact on Fe uptake in either the absence or presence of IPs. Cellular acquisition of Fe from solutions containing IPs was further enhanced by simultaneous addition of essential amino acids and AA. The stimulatory influence of ascorbic acid on Fe uptake from solutions containing IP6 was associated with an increase in the level of ferrous ion. These data further support the usefulness of Caco-2 cells as a model for investigating the effects of various dietary factors on mineral bioavailability.

Ascorbic Acid↗

PubMed1994

Inositol phosphates inhibit uptake and transport of iron and zinc by a human intestinal cell line.

To examine the influence of inositol phosphates on the uptake and absorption of Fe and Zn, Caco-2 cells were grown on either plastic (uptake studies) or porous membranes in bicameral chambers (transport/absorption studies). Caco-2, a human colon adenocarcinoma cell line, was selected as the test cell because it spontaneously differentiates into polarized enterocyte-like cells at confluency. Uptake of Fe (added as Fe-nitrilotriacetate complex) from a calcium-free solution by fully differentiated cells was 37 pmol/cm2. Addition of 10-fold molar excess of individual inositol phosphates (IP3, IP4, IP5 or IP6) decreased Fe solubility by 13 to 25% and reduced Fe uptake by 50 to 65%. The rate of transport of Fe from the apical solution into the basolateral chamber [1.4 +/- 0.1 pmol/(h.cm2)] decreased (34-96%) in proportion to the degree of phosphorylation of the inositol derivative in the apical compartment. Uptake and transepithelial transport of Zn were 246 +/- 5 pmol/cm2 and 23 +/- 1 pmol/(h.cm2), respectively. The solubility, uptake and rate of transport of Zn also decreased in proportion to the degree of phosphorylation of inositol. These results demonstrate the inhibitory influence of IP3-IP6 on the uptake and transport of Fe and Zn and support the usefulness of the Caco-2 human cell line as an appropriate model for evaluating the effects of specific dietary factors on trace metal bioavailability.

Colonic Neoplasms↗

PubMed1994

Exercise-induced changes in immune function: effects of zinc supplementation.

To examine the effect of zinc (Zn) supplementation on exercise-induced changes in immune function, five male runners were randomly assigned in a double-blind crossover design to take a supplement (S; 25 mg of Zn and 1.5 mg of copper) or placebo (P) twice daily for 6 days. On morning 4 of each phase, 1 h after taking S or P, subjects ran on a treadmill at 70-75% of maximal oxygen uptake until exhaustion (approximately 2 h). Blood samples were obtained before (Pre), immediately after (Post), and 1 (Rec1) and 2 (Rec2) days after the run. [3H]thymidine incorporation by mitogen-treated mononuclear cell cultures was significantly lower (P < 0.05) Post than Pre, Rec1, or Rec2 for both S and P. Respiratory burst activity of isolated neutrophils was enhanced after exercise with P but not with S (P: Pre 12.0 +/- 1.1 vs. Post 17.6 +/- 2.3 nmol O2-/10(6) cells; S: Pre 11.7 +/- 0.3 vs. Post 12.1 +/- 1.2 nmol O2-/10(6) cells). Thus supplemental Zn blocked the exercise-induced increase in reactive oxygen species. Whether this antioxidant effect of Zn will benefit individuals exposed to chronic physical stress remains to be determined.

Adult↗

PubMed1993

Copper repletion restores the number and function of CD4 cells in copper-deficient rats.

Dietary copper deficiency decreases the number of splenic CD4 cells and mitogen-induced generation of interleukin-2 activity and DNA synthesis in cultures of splenic mononuclear cells. To determine the reversibility of these defects, Cu-deficient rats were fed a Cu-adequate diet for either 4, 7 or 11 d before preparation of cell cultures. Serum and hepatic concentrations of Cu attained 87 and 75%, respectively, of the control level after 4 d of dietary repletion. In contrast, interleukin-2 activity and [3H]thymidine incorporation in splenic cell cultures treated with T-cell mitogens were significantly greater than in cultures from Cu-deficient rats after 7, but not 4, d of dietary Cu repletion. The number of splenic CD4 cells was also greater after 7 d of dietary supplementation with Cu. Changes in the relative percentage and function of T-helper cells were highly correlated with one another and with hepatic Cu concentration. These observations indicate that an inadequate supply of dietary Cu reversibly suppresses the maturation and function of splenic T-helper cells.

Animals↗

PubMed1993

Copper deficiency alters collagen types and covalent cross-linking in swine myocardium and cardiac valves.

Dietary copper deficiency induces alterations of connective tissue metabolism that are associated with lesions in cardiovascular and other organ systems. To determine the impact of copper deficiency on characteristics of collagen in porcine myocardium and cardiac valves, weaned pigs were fed diets with adequate or deficient levels of copper. Although dietary copper did not affect the concentration of collagen in either myocardium or bicuspid valves, the degree of collagen cross-linking, as assessed by the level of hydroxylysylpyridinoline, was lower in both tissues of copper-deficient pigs. Proportions of type III collagen were increased in the left ventricle and bicuspid valves of copper-deficient pigs. Copper deficiency induced extensive remodeling, however, of the collagen fraction of cardiac interstitium. Reduction in left ventricular collagen cross-linking may provide the stimulus for the development of cardiac hypertrophy, which characterizes severe copper deficiency, by increasing the compliance of the ventricular wall. The shift in the phenotypic profile of collagen that is associated with this cardiac hypertrophy indicates synthesis of new collagen, which could affect collagen cross-linking irrespective of copper status.

Animals↗

PubMed1993

Fructose utilization by the human intestinal epithelial cell line, Caco-2.

The potential use of Caco-2 cells as a model for the study of fructose metabolism and transport in the intestine was evaluated, since this human cell line exhibits many of the anatomical and biochemical characteristics of mature enterocytes. Pre- and postconfluent cultures converted [14C]fructose to CO2, lipid, and glycogen. Apparent utilization of [14C]fructose was less than that of [14C]glucose. This difference was due in part to the more rapid uptake of glucose from medium as compared with fructose. Addition of glucose, galactose, and mannose to medium markedly decreased the metabolism, while slightly inhibiting the uptake, of [14C]fructose. These data demonstrate that fructose can serve as a carbon and energy source for Caco-2 cells, and that common dietary monosaccharides affect the efficiency of fructose metabolism.

Adenocarcinoma↗

PubMed1992

Copper deficiency reversibly impairs DNA synthesis in activated T lymphocytes by limiting interleukin 2 activity.

The essentiality of adequate copper (Cu) nutriture for normal T-cell function in laboratory and domestic animals is well established. However, specific biochemical roles of Cu in the maturation and activation of T cells have not been defined. Previous work showed that when cultures of splenic mononuclear cells (MNCs) from Cu-deficient rats were exposed to T-cell mitogens, DNA synthesis was markedly reduced despite normal up-regulation of interleukin 2 (IL-2) receptors, transferrin receptors, and class II major histocompatibility complex molecules. In the present study, IL-2 activity in PHA-treated cultures of MNCs from Cu-deficient rats was 40-50% that of controls as determined by bioassay. Addition of rat IL-2 to phytohemagglutinin-treated cultures of MNCs from Cu-deficient rats increased blastogenic activity to control levels, demonstrating that Cu deficiency does not inhibit transition of quiescent cells to the competence phase of the activation process. Moreover, supplementation of MNC cultures from Cu-deficient rats with physiological levels of Cu enhanced IL-2 activity and DNA synthesis in response to phytohemagglutinin. These data indicate that IL-2 activity in cultures of activated splenic T lymphocytes from Cu-deficient rats is insufficient for optimal blastogenesis.

Animals↗

PubMed1992

Effects of copper deficiency on T-cell mitogenic responsiveness and phenotypic profile of blood mononuclear cells from swine.

The effect of dietary copper deficiency on T-cell mitogenic responsiveness and phenotypic profile of blood mononuclear cells (MNC) in weaned pigs was examined. Outbred, weaned pigs were fed a semipurified diet containing adequate (6.4 mg/kg of body weight) or deficient (0.8 mg/kg) amounts of Cu. Pigs fed the low Cu diet for 10 weeks had markedly decreased concentrations of Cu in liver and plasma, and hypertrophic hearts. In vitro reactivity of MNC from Cu-deficient pigs to phytohemagglutinin and concanavalin A was significantly suppressed. This functional impairment was not associated with a decrease in the percentage of T cells, CD4 or CD8 cell subsets, or B cells. Expression of SLA-DQ and SLA-DR class II major histocompatibility complex (MHC) antigens was increased by Cu deficiency, the former significantly. Unlike rodents, in which inadequate Cu nutriture induces functional T cell deficiency that is associated with a decrease in the CD4 T-cell subset, swine fed inadequate Cu diets for 10 weeks had no changes in MNC subsets yet clearly manifested functional impairment of T-cell responses.

Animals↗

PubMed1991

Lipoprotein status in Sprague-Dawley and LA/N-corpulent rats as affected by dietary carbohydrates.

1. To compare the impact of type of carbohydrate, genotype and phenotype on the synthesis and levels of plasma lipoprotein protein. Sprague-Dawley rats and carbohydrate-sensitive LA/N-corpulent (cp) rats were fasted (2 days) and then fed diets containing 54% carbohydrate as either sucrose, fructose or cooked cornstarch for 2 days. 2. The amount of 3H-protein present in the VLDL + chylomicron fraction of Sprague-Dawley rats 2 hr after injection of 3H-leucine was affected by type of dietary carbohydrate: sucrose greater than fructose greater than starch. 3. Obese and lean LA/N-cp rats fed diets containing sucrose or fructose had lower concentrations of HDL protein and higher levels of 3H-protein in VLDL + chylomicron fraction than those fed starch. 4. Obese LA/N-cp rats had more HDL protein and higher levels of 3H-protein in VLDL + chylomicron fraction than their lean littermates.

Animals↗

PubMed1991

Cardiac catecholamine metabolism in copper-deficient rats.

After parturition, Sprague-Dawley dams were fed diets containing either 0.6 (-Cu) or 6 (+Cu) mg of copper/kg of diet. Pups were weaned either to the diet of their dam or to the diet fed to dams in the other treatment group in a crossover design. At 7 wk of age, Cu-deficient rats were characterized by low tissue Cu and an enlarged heart with increased levels of dopamine (DA) and decreased levels of norepinephrine (NE). These changes resulting from Cu deficiency were independent of gender. In vivo synthesis of cardiac NE from DA in Cu-adequate rats was significantly greater than in Cu-deficient rats. Turnover of cardiac NE was estimated from the temporal change in the specific activity of [3H]NE. Fractional turnover rates (percentage per hour) of cardiac NE were similar in both dietary groups, although the cardiac turnover of NE (nanograms per hour) was 1.4-fold higher in Cu-adequate rats than in Cu-deficient rats. Repletion of Cu-deficient rats with dietary Cu increased the total amount of cardiac NE to 78 and 93% of control values after 1 and 2 d, respectively. Significant changes in the quantities of NE and DA in the heart of rats whose intake of Cu was restricted from birth were first detected at 4 wk of age, but cardiac hypertrophy was not observed until 5 wk of age. The data support the proposal that the altered levels of DA and NE in the heart of Cu-deficient rats are primarily the result of decreased activity of DA-B-monooxygenase and demonstrate that Cu supplementation rapidly repletes cardiac NE in Cu-deficient rats. Moreover, changes in the concentrations of NE and DA in the heart precede and may contribute to the development of cardiac hypertrophy.

Animals↗

PubMed1991

Alterations in splenic lymphoid cell subsets and activation antigens in copper-deficient rats.

Rats were nursed by dams fed a diet containing adequate (6 micrograms/g) or deficient (0.6 micrograms/g) Cu during the lactation period and weaned to the same diet. Splenic mononuclear cells were isolated and the phenotypic profile determined by flow cytometry after immunolabelling with monoclonal antibodies to cell surface markers. Total splenic mononuclear cell yield and the relative percentage and absolute number of T-cells and the CD4+ (helper) and CD8+ (cytotoxic) T-subsets were decreased in Cu-deficient male rats. The relative percentage, but not the absolute numbers, of splenic B-cells and macrophages was increased by Cu deficiency. The percentage of splenic mononuclear cells from male rats that expressed interleukin-2 receptors and transferrin receptors in vivo was increased by Cu deficiency. In contrast, dietary Cu deficiency did not affect the yield and phenotypic profile of splenic mononuclear cells in female rats. Reactivity of splenic mononuclear cells to T-cell mitogens was decreased in Cu-depleted male and female rats. However, mitogen-induced increases in levels of interleukin-2 receptor and transferrin receptor were similar in cultures of splenic mononuclear cells obtained from control rats and rats subjected to restricted dietary intake of Cu only during the postlactation period. Thus, decreased mitogenic blastogenesis on exposure of cells from Cu-deficient rats does not reflect a nonspecific impairment of cellular activation.

Animals↗

PubMed1990

Consequences of copper deficiency are not differentially influenced by carbohydrate source in young pigs fed a dried skim milk-based diet.

Carbohydrates (CHO) such as fructose (FR) or sucrose, but not starch (ST), aggravate the consequences of dietary copper (Cu) deficiency in rats. To evaluate whether this Cu X CHO interaction is pertinent to human health, the pig was used as an animal model. In two studies, 66 weanling pigs were fed dried skim milk (DSM)-based diets for 10 wk with 20% of the total calories provided as either FR, glucose, or ST and containing either deficient (1.0-1.3 micrograms/g diet) or adequate (7.1 micrograms/g) levels of Cu. Plasma and tissue levels of Cu, the activities of plasma ceruloplasmin ferroxidase and erythrocyte Cu, Zn-superoxide dismutase, and hematocrits were lower (p less than 0.05) in animals fed Cu-deficient diets. The relative cardiac mass of all Cu-deficient groups was greater (p less than 0.05) than that of animals fed Cu-adequate diets. These effects were in general unaffected by type of CHO. For comparison, weaned male rats were also fed DSM-based containing diets ST or FR with adequate or deficient Cu for as long as 10 wk. Rats consuming the Cu-deficient diets were characterized by significantly lower hematocrits, decreased tissue Cu levels, and enlarged hearts, regardless of the CHO source. Together, these data demonstrate that DSM-based diets are not suitable for delineation of potential Cu X CHO interactions, and one or more components of DSM may exacerbate the consequences of dietary Cu deficiency.

Animal Feed↗

PubMed1990

Cardiac and splenic levels of norepinephrine and dopamine in copper deficient pigs and rats.

1. Copper deficiency decreased the concentration and content of norepinephrine in the hearts of pigs and rats. 2. Concentration, but not content, of norepinephrine was decreased in spleen of copper-deficient pigs, while splenic norepinephrine levels in rats were not altered by copper deficiency. 3. Cardiac and splenic concentrations and contents of dopamine were elevated in copper-deficient pigs and rats. 4. Tissue concentrations of catecholamines and the magnitude of change due to copper deficiency were greater in pigs than rats.

Animals↗

PubMed1990

Consequences of severe copper deficiency are independent of dietary carbohydrate in young pigs.

The ability of carbohydrates (CHO), such as fructose and sucrose, to aggravate copper deficiency in rats and the recent dietary trends of Western human populations led to the suggestion that the Cu X CHO interaction may be pertinent to public health. This hypothesis was tested with pigs because their cardiovascular and gastrointestinal systems closely resemble those of humans. Weanling pigs were fed a diet containing either 59% sucrose or cornstarch with either deficient (0.8 mg/kg diet) or adequate (6.4 mg/kg) copper for 10 wk. Plasma and tissue copper, the activities of plasma ceruloplasmin ferroxidase and erythrocyte Cu,Zn-superoxide dismutase, hematocrits, and serum cholesterol and triglyceride were all decreased (p less than 0.05) and relative cardiac mass was increased (p less than 0.05) by severe dietary copper deficiency. The type of dietary CHO did not differentially influence the values of these variables. Thus, these data fail to support the hypothesis that the Cu X CHO interaction observed in rats represents a health risk for humans.

Animals↗

PubMed1990

Respiratory burst and candidacidal activity of peritoneal macrophages are impaired in copper-deficient rats.

To investigate the effect of dietary copper deficiency on the function of peritoneal macrophages, weaned male Lewis rats were pair-fed diets containing either adequate (7 mg/kg diet; +Cu) or deficient (0.7 mg/kg diet; -Cu) levels of copper for 5 wk. Cellular copper content and the activity of Cu, Zn superoxide dismutase were significantly lower in both resident and thioglycollate-elicited macrophages from -Cu rats than in cells from +Cu controls. Reduced cellular Cu status was associated with impaired respiratory burst as assessed by zymosan-induced chemiluminescent activity and superoxide anion (O2-) generation. Candidacidal activity of macrophages from -Cu rats was also reduced and was highly correlated with chemiluminescent activity and O2- generation. In contrast, phagocytosis of opsonized erythrocytes by peritoneal macrophages from -Cu rats was normal. Elicited peritoneal macrophages from marginally Cu-deficient rats also killed significantly fewer yeast cells than macrophages from +Cu rats. These results demonstrate that macrophage function is impaired by dietary Cu deficiency and that the candidacidal activity of these cells may provide a sensitive indicator of Cu status.

Animals↗