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M L Failla

Publications and source records attributed to M L Failla.

At least 55 records · Page 3Linked to original sources
PubMed1990

Copper status and function of neutrophils are reversibly depressed in marginally and severely copper-deficient rats.

Weaned male 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 Cu concentration, activity of Cu,Zn superoxide dismutase (Cu,Zn-SOD), generation of superoxide anion (O2-) in response to opsonized zymosan and phorbol myristate acetate, and candidacidal activity in elicited neutrophils were all significantly decreased by dietary Cu deficiency. Furthermore, survivability of Candida albicans injected into the peritoneal cavity of Cu-deficient rats was greater than in controls. Phagocytic activity of neutrophils was independent of cellular Cu status. To determine whether the impaired function of neutrophils was also characteristic of marginal Cu deficiency, weaned rats were fed diets containing either 0.6, 1.1, 2.0, 2.7 or 6.7 (control) mg Cu/kg for 5 wk. The activity of Cu,Zn-SOD, phorbol myristate acetate-induced production of O2-, and candidacidal activity were significantly lower in neutrophils from rats fed diets with less than or equal to 2.7 mg Cu/kg compared to control cells. In contrast, decreased tissue Cu and the activity of erythrocyte Cu,Zn-SOD were observed only when dietary Cu was less than or equal to 2.0 mg/kg. Reduced SOD activity, respiratory burst and candidacidal activity of neutrophils were evident as soon as 1 wk after initiating the dietary treatment. Feeding +Cu diet to Cu-deficient rats for 1 wk restored Cu status and function of neutrophils to control levels. These results show that neutrophil function is reversibly impaired by marginal and severe Cu deficiency and suggest that the Cu status and function of these cells may provide a sensitive indicator for assessment of Cu status.

Animals↗
PubMed1989

Accumulation and transport of cadmium by tolerant and susceptible strains of Mycobacterium scrofulaceum.

Cadmium accumulation and transport were studied in two strains of Mycobacterium scrofulaceum differing in their susceptibility to Cd2+ toxicity. A 10-fold excess of either Zn2+ or Mn2+ partially antagonized inhibition of growth by Cd2+. 109Cd2+ uptake by both the tolerant and susceptible strains was temperature dependent and inhibited by a 10-fold excess of either Zn2+ or Mn2+. There were no significant differences in either the kinetics of 109Cd2+ uptake or the retention of accumulated 109Cd2+ by the tolerant and susceptible strains. Both tolerant and susceptible strains removed most of the cadmium from the culture medium, but significantly more was removed by cells of the tolerant strain. Most of the accumulated Cd2+ in the tolerant strain was in the particulate fraction, rather than in the soluble fraction. Intracellular accumulated Cd2+ was primarily in the soluble fraction of the susceptible strain. Increased Cd2+ in culture medium resulted in decreased Mn2+ and Zn2+ in cells of the susceptible strain but did not reduce the Mn2+ and Zn2+ content of cells of the tolerant strain.

Cadmium↗
PubMed1989

Degradation of zinc-metallothionein in monolayer cultures of rat hepatocytes.

The degradation of zinc-metallothionein (MT) was studied in monolayer cultures of adult rat hepatocytes. Hepatocytes were incubated overnight in serum-free medium containing either [35S]cysteine or [3H]leucine and 100 microM zinc to induce MT synthesis. Total cellular 35S-MT was measured in the heat-stable extract of cell homogenate and quantified by fast protein liquid chromatography. When zinc was removed from the medium, 35S-MT turnover was almost 3-fold faster than that of [3H]Leu protein (t1/2 = 11 and 29 hr, respectively). The decrease in the cellular level of 35S-MT reflected degradation since less than 1% of total cellular 35S-MT was secreted into the medium. The rate of MT degradation was inversely proportional to cellular zinc content. In contrast, the degradation of [3H]Leu protein was not affected by changes in cellular zinc concentration. Chloroquine, a lysosomotrophic amine, and tosyl lysine chloromethyl ketone, an inhibitor of trypsin-like neutral protease activity, inhibited 35S-MT degradation by 65% and 50%, respectively, when cells were incubated in medium with 1 microM zinc. Turnover of [3H]Leu protein, but not 35S-MT, was enhanced by insulin deprivation. These data suggest that the degradation of hepatic MT (i) is primarily regulated by cellular zinc content and (ii) occurs in both lysosomal and nonlysosomal compartments.

Animals↗
PubMed1988

Metallothionein metabolism in the liver and kidney of the streptozotocin-diabetic rat.

1. Elevated levels of metallothionein (MT)-I and -II were identified in the liver and kidney of insulin-deficient diabetic rats. 2. The relative rate of MT synthesis and the turnover of cytoplasmic MT were both accelerated in the liver of diabetic rats. 3. The rate of synthesis of MT, but not its cytoplasmic turnover, was increased in diabetic kidney. 4. Maximal relative rates of MT synthesis in liver and kidney were first observed at 4 and 10 days, respectively, after inducing the diabetic condition. 5. The altered metabolism of hepatic MT in diabetic rats was attributed primarily to disturbances in endocrine status, while the altered metabolism of renal MT was largely due to accumulation of excessive dietary copper in the kidney.

Animals↗
PubMed1988

Iron metabolism in genetically obese (ob/ob) mice.

Several reports in the clinical literature suggest that obese children may be at risk for developing iron deficiency. Here the absorption, retention, tissue distribution and tissue levels of iron were compared in lean (+/?) and obese (ob/ob) C57BL/6J mice to examine the impact of obesity on the iron status of this animal model. Obese mice absorbed and retained approximately twice as much 59Fe as lean mice after receiving a solution containing 1 mumol iron per os. This difference was independent of age, severity of obesity and mass of the gastrointestinal tract. Obese mice fed ad libitum had higher levels of 59Fe in blood and fat pads, but lower amounts of 59Fe in the skeletal-muscular system, than lean mice 6 d after subcutaneous injection of 1 mumol of the metal. At least 30% of carcass 59Fe was present in the liver of obese and lean mice 6 d after injection. Despite significantly lower concentrations of iron in liver and bone, blood hemoglobin and hematocrit were significantly higher in obese mice fed ad libitum than in lean mice at 10 wk of age. Plasma iron and transferrin were not affected by chronic obesity. Although several characteristics of iron metabolism differed in obese and lean mice, the results indicate that ob/ob mice were not iron deficient when fed a diet containing an adequate level of this micronutrient. The increased absorption of iron by obese mice probably represents an adaptive response that is required to supply additional micronutrient for the expanded blood volume in these animals.

Absorption↗
PubMed1988

Use of immunoresponsiveness to demonstrate that the dietary requirement for copper in young rats is greater with dietary fructose than dietary starch.

Weaned male Lewis rats were pair-fed diets containing 62.7% fructose or starch and either 6-7 mg Cu/kg diet (adequate) or 0.7 mg Cu/kg diet (deficient) for 33 d. Antibody titers after primary immunization with sheep erythrocytes were significantly lower in rats fed copper-deficient diets. Compared to starch, fructose markedly attenuated antibody production in copper-deficient rats. Dietary carbohydrate did not affect the humoral immune response of rats fed diets with adequate copper. Concentrations of copper in thymus, spleen, liver and heart were also significantly lower in rats fed fructose with deficient copper (F-Cu) than in the group fed starch with deficient copper. Thymic hypogenesis was observed only in the F-Cu group. Tissue concentrations of copper were reduced before antibody production was impaired. Repletion of previously copper-deficient rats rapidly restored immunocompetence and stimulated thymic growth. Immunoresponsiveness and tissue concentrations of copper reached control levels in rats fed diets containing starch and fructose at 1.2-1.6 and 2.2-2.9 mg Cu/kg diet, respectively. The results demonstrate that the amount of dietary copper required for optimal function of the humoral immune system, thymic growth and maintenance of normal tissue levels of this essential micronutrient is greater when young rats are fed diets with fructose than with starch.

Animals↗
PubMed1987

Accumulation and metabolism of iron-dextran by hepatocytes, Kupffer cells and endothelial cells in the neonatal pig liver.

Treatment of newborn pigs with supplemental iron is a common procedure utilized to prevent neonatal anemia. The aim of this study was to investigate the hepatic distribution and intracellular metabolism of iron-dextran, a widely used colloidal-iron-carbohydrate preparation. Piglets were injected intramuscularly with iron-dextran (50 mg Fe/kg body wt) at 1 d of age. Hepatocytes and sinusoidal cells (Kupffer cells and endothelial cells) were isolated from iron-treated and control (uninjected) piglets at 2, 6 and 11 d of age. The concentrations of iron, copper and zinc in isolated cells were determined by atomic-absorption spectroscopy. In addition, the quantities of ferritin-protein and ferritin-iron were measured by immunoelectrophoresis and ion-exchange chromatography, respectively. At 2 d of age, the concentration (microgram/mg cell protein) of iron was 5-, 62- and 54-fold higher in hepatocytes, Kupffer cells and endothelial cells, respectively, isolated from iron-treated piglets than from control piglets. Hepatocytes, Kupffer cells and endothelial cells accumulated ferritin in response to iron-dextran treatment. Higher concentrations of ferritin-protein and ferritin-iron were present in Kupffer cells and endothelial cells than in hepatocytes at all times after treatment with iron-dextran. The percentage of cellular iron that was associated with ferritin, however, was greater in hepatocytes than in sinusoidal cells. Iron accumulated by all three liver cell types was mobilized to extrahepatic sites. Slight alterations in zinc and copper status of liver cells were evident at 11 d of age as a result of iron treatment.

Animals↗
PubMed1987

Zinc metabolism in genetically obese (ob/ob) mice.

Recent reports indicate that the concentrations and total amounts of several essential trace metals in various tissues of genetically obese rodents differ markedly from those in lean controls. In the present studies the absorption, retention and tissue distribution of zinc and constitutive levels of zinc-metallothionein (Zn-MT) in selected tissues were compared in obese (ob/ob) and lean (+/?) C57BL/6J mice. When 5-, 10- and 22-wk-old mice were administered 1.2 mumol 65Zn by stomach tube the apparent absorption of 65Zn by obese mice was 1.5, 2.2 and 3.9 times higher, respectively, than that in age-matched lean mice. Retention of orally administered 65Zn after 96 h was also substantially higher in obese mice than in lean mice. To assess the possible influences of hyperphagia and intestinal hypertrophy on the enhanced apparent absorption of 65Zn by obese mice food intake by an additional group of obese mice was restricted to that of age-matched lean controls. When actual absorption of zinc was determined according to the method of Heth and Hoekstra, groups of ad libitum--fed obese, pair-fed obese and lean mice absorbed 38, 32 and 18% of administered 65Zn, respectively. In contrast, the rate of 65Zn excretion 2-6 d after oral or subcutaneous administration of the metal was similar for obese and lean mice. Unrestricted and pair-fed obese mice had significantly lower percentages of carcass 65Zn present in skin, muscle plus bone, spleen and testes and higher percentages present in liver, small intestine and adipose tissue than lean mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Lack of an effect of dietary fructose on severity of zinc deficiency in rats.

Because feeding rats diets containing fructose as the carbohydrate source reduces copper and selenium status, we investigated whether the type of dietary carbohydrate also affected indices of zinc status. The experimental design was a 2 X 2 factorial study with the source of dietary carbohydrate (cornstarch or fructose) and the level of dietary zinc (0.7 or 31 micrograms Zn/g) as the variables. The experiment utilized 76 weanling male Sprague-Dawley rats randomly assigned to one of four dietary groups. Animals fed a zinc-deficient fructose diet were allowed to consume the diet ad libitum; all other groups were pair-fed to that group to ensure equivalent nutrient and energy intake. The results of the 29-d study showed that the most sensitive indices of zinc status measured, including growth, survival and the zinc concentrations of plasma, femur and testes, were not affected by the type of dietary carbohydrate. This lack of an effect of fructose on the zinc status of the experimental animals indicates that the ability of fructose to exacerbate copper and selenium deficiencies is specific, rather than representing a generalized effect of this simple sugar on the requirements and/or metabolism of all essential trace elements.

Animals↗
PubMed1987

Plasmid-encoded copper resistance and precipitation by Mycobacterium scrofulaceum.

A copper-tolerant Mycobacterium scrofulaceum strain was able to remove copper from culture medium by sulfate-dependent precipitation as copper sulfide. Such precipitation of copper sulfide was not observed in a derivative that lacks a 173-kilobase plasmid. In addition, the plasmid-carrying strain has a sulfate-independent copper resistance mechanism.

Chemical Precipitation↗
PubMed1987

Effects of extreme hyperinsulinaemia on serum levels of trace metals, trace metal binding proteins, and electrolytes in normal females.

In order to assess the possible effects of insulin on serum concentrations of trace metals (iron, copper, zinc) and trace metal binding proteins (ferritin, transferrin, coeruloplasmin), five normal females were studied with the hyperinsulinaemic-euglycaemic clamp technique. A 0.1 U/kg insulin bolus was administered, followed by an insulin infusion at a rate of 10 mU/kg/min for 12-16 h. Insulin levels of 1500-2000 microU/ml (9.21-12.28 nmol/l) were attained. When iron levels in serum were assayed colorimetrically, there appeared to be a progressive rise in the mean concentration during the course of the insulin infusion. Direct analysis of serum samples by atomic absorption spectrophotometry also showed that the level of non-haeme iron increased 3-fold in the serum of the subject with the lowest concentration of this metal at the start of the study. In contrast with the results for serum iron, the levels of ferritin, total iron binding capacity (transferrin), zinc, copper and coeruloplasmin were not altered in any subject during the insulin infusion or at 24 h following discontinuation of the infusion. Within 4 h of institution of the hyperinsulinaemic clamp significant reductions in serum levels of potassium, phosphorus, cholesterol, total protein and albumin were noted. As the insulin infusion progressed, the urea nitrogen, uric acid and bicarbonate levels fell as well. These observations suggest that supraphysiologic hyperinsulinaemia of 12-16 h duration may alter serum levels of iron, but not serum levels of zinc, copper or trace metal binding proteins in some individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Adaptation of the duodenum and ileum of the rat to mid-gut resection: enzyme activity and trace metal status.

Activities of the enzymes lactase, sucrase, maltase, alkaline phosphatase, and superoxide dismutase (SOD) were measured in mucosa of duodenum and ileum of the rat after 70% resection of mid-small intestine or sham operation (transection). We also measured the concentrations of zinc, copper, and manganese in several tissues to assess trace metal homeostasis postresection. Resection resulted in decreased specific activities of disaccharidases and alkaline phosphatase in duodenum, while specific activities remained unchanged in ileum. Specific activity of total SOD (the sum of Cu-Zn and Mn SOD) and Mn SOD was the same in duodenum after resection but was markedly increased in ileum. Tissue trace metal concentrations changed minimally. Because of postresection mucosal growth, total segmental activity of disaccharidases and alkaline phosphatase was the same in duodenum and increased in ileum of resected compared to transected rats. Segmental activity of total SOD and Mn SOD doubled in duodenum and trebled in ileum of resected as compared to transected rats. Thus, total segmental enzyme activity is maintained or increased postresection by increased enterocyte proliferation rate and mucosal growth.

Alkaline Phosphatase↗
PubMed1986

Influence of genetic obesity on tissue concentrations of zinc, copper, manganese and iron in mice.

The concentrations (micrograms/gram dry wt) of four essential trace metals in various tissues from C57BL/6J lean (+/?) and obese (ob/ob) mice were determined. Lower concentrations of zinc were found in liver, femur, small intestine and muscle from obese mice than in those from lean mice at 22 wk of age. The concentrations of copper in liver, femur, small intestine, muscle and testes, iron in liver, femur, muscle and plasma, and manganese in liver, femur and small intestine from adult obese mice were also significantly below the concentrations present in tissues from age-matched lean mice. Hepatic concentrations of zinc, copper and manganese in obese mice were also lower than those in lean mice when the different amounts of neutral lipid in obese and lean liver were considered. In contrast with the trend towards lower concentrations of trace metals in tissues from adult obese mice, plasma zinc and copper levels and ceruloplasmin activity were higher in adult obese mice than in lean controls. The effect of genetic obesity on tissue trace metals concentrations was similar in male and female mice. Several tissues from young (5-6 wk of age) obese mice also had lower concentrations of the trace metals than age-matched lean mice, although the differences were not as great as in adults. These data demonstrate that chronic obesity in the genetically obese (ob/ob) mouse is associated with lower concentrations, but not necessarily lower total quantities, of several inorganic micronutrients in tissues. The possibility tht chronic obesity alters the nutritional requirements for these trace metals is discussed.

Animals↗
PubMed1985

Isolation and culture of parenchymal and nonparenchymal cells from neonatal swine liver.

Procedures for the isolation and monolayer culture of hepatocytes and nonparenchymal (Kupffer and endothelial) cells from livers of neonatal pigs (1 to 15 d of age) are described. Cell suspensions were obtained by a modification of the two-step collagenase perfusion technique. Hepatocytes were collected by low-speed centrifugation and nonparenchymal cell populations were purified by centrifugal elutriation. Hepatocytes were readily maintained in arginine-free medium fortified with either fetal calf serum or bovine serum albumin and oleate for periods as long as 6 d. The ability of cultured hepatocytes to incorporate 3H-leucine and 3H-thymidine into protein and DNA, respectively, demonstrated that cells were metabolically active for at least 3 d in culture. The 3H-leucine incorporation into total cell protein was constant regardless of animal age at the time of cell isolation, while incorporation of 3H-thymidine was influenced by animal age. Incorporation of both precursors was dependent upon duration of culture period in vitro and the type of medium (serum-free vs serum-containing) in which the cells were maintained. Morphological observation and analysis of the DNA and protein levels of hepatocyte monolayers suggest that cells did not replicate during the 3-d incubation period. The ability to isolate and culture metabolically active, nonreplicating hepatocytes from neonatal pigs in a serum-free medium affords opportunities for investigation of the influence of specific hormones and specific growth factors on the uptake and metabolism of nutrients by the liver. Similarly, the neonatal pig will serve as a useful model for the characterization of hepatic nonparenchymal cell metabolism during the neonatal period.

Animals↗
PubMed1985

Influence of spontaneous diabetes on tissue status of zinc, copper, and manganese in the BB Wistar rat.

The concentrations of zinc, copper, and manganese in liver, kidney, duodenum, pancreas, testes, bone, and serum from control and untreated, spontaneously diabetic BB Wistar rats were compared. Chronic insulin deficiency resulted in significant alterations in the concentrations of one or more of these essential micronutrients in several tissues. The amounts of zinc and copper bound to metallothionein in the liver and kidney of untreated spontaneously diabetic rats were also markedly increased. The tissue trace metal status in diabetic rats was altered similarly in both male and female rats. Daily injections of insulin blocked many of the changes in the tissue concentrations of the metals. The effects of spontaneous diabetes on tissue trace metal status are quite similar to those reported for chemically induced diabetes. Thus, these results demonstrate that chronic endocrine imbalance is responsible for a series of tissue specific changes in the transport and metabolism of zinc, copper, and manganese.

Animals↗
PubMed1984

Cadmium metabolism by rat liver endothelial and Kupffer cells.

The metabolism of cadmium was investigated in Wistar-rat liver non-parenchymal cells. Kupffer and endothelial cells, the major cell populations lining the sinusoidal tracts, were isolated by collagenase dispersion and purified by centrifugal elutriation. At 20 h after subcutaneous injection of the metal salt (1.5 mg of Cd/kg body weight), endothelial cells accumulated 2-fold higher concentrations of Cd than did Kupffer or parenchymal cells. Most of the Cd in non-parenchymal cells was associated with cytosolic metallothionein (MT), the low-Mr heavy-metal-binding protein(s). When MT was quantified in cytosols from cells isolated from control rats by a 203Hg competitive-binding assay, low levels were found to be present in Kupffer, endothelial and parenchymal cells. Cd injection significantly increased MT levels in all three cell types. The induction of MT synthesis was investigated in vitro by using primary monolayer cultures. The incorporation of [35S]cysteine into MT increased 47% over constitutive levels in endothelial-cell cultures after the addition of 0.8 microM-Cd2+ to the medium for 10 h. MT synthesis in Kupffer cells was not observed. The lack of MT synthesis by monolayer cultures of Kupffer cells in vitro was associated with a decreased capacity of these cells to accumulate heavy metals from the extracellular medium. This apparent decreased ability to transport metals did not reflect a general defect in either cellular function or metabolic activity, since isolated Kupffer cells incorporated [3H]leucine into protein at rates comparable with those shown by liver parenchymal cells and readily phagocytosed particles.

Animals↗
PubMed1984

Urinary excretion of zinc, copper and iron in the streptozotocin-diabetic rat.

The influence of the chemically diabetic condition on urinary excretion of zinc, copper and iron was investigated. Male Sprague-Dawley rats were injected with streptozotocin to induce insulin-dependent diabetes (day 0) and 24-hour urinary collections taken 1, 4, 7, 10 and 14 days later. Onset of the diabetic condition was correlated with a rapid and persistent increase in the amounts of the three trace metals excreted daily in the urine. Diabetic rats excreted 3.4-, 5.0- and 4.9-fold more zinc, copper and iron, respectively, than controls in the urine on day 14. Insulin treatment of diabetic rats significantly reduced the quantities of the micronutrients excreted in urine, suggesting that altered hormonal status was the primary cause of increased urinary losses. Enhanced urinary output of the metals was not associated with reduction in the plasma, liver and kidney contents of zinc, copper and iron. Urinary trace metal excretion was correlated with food ingestion and urinary volume with greater amounts lost during the dark period for control and diabetic animals. The influence of endocrine status on urinary excretion of trace metals is discussed.

Animals↗