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M L Failla

Publications and source records attributed to M L Failla.

At least 73 records · Page 4Linked to original sources
PubMed1984

Influence of molybdenum and sulfate supplementation and withdrawal of diets containing high copper broiler litter on tissue copper levels in ewes.

Thirty-six mature, nongestating, crossbred ewes were allotted randomly to three diets for 140 d: basal (six ewes); 50% basal and 50% broiler litter, dry basis (24 ewes) and 50% basal and 50% deep stacked broiler litter with the addition of 25 ppm molybdenum (Mo) and 5 g sulfate (SO4)/kg feed (six ewes). The control diet and the broiler litter contained 8 and 257 ppm Cu, dry basis, respectively. Liver samples from six ewes in each group were obtained by biopsy initially and at 40, 80 and 120 d and at slaughter (140 d). The remaining 18 litter-fed ewes were fed the basal diet after 140 d and six were slaughtered after 30-, 60- and 120-d. Liver Cu content continually increased (P less than .01) by feeding broiler litter (404 vs 1,543 ppm, dry basis), and was decreased (962 ppm) by supplementing Mo and SO4. During the withdrawal period, liver and duodenum Cu levels were not reduced (P greater than .05). A linear increase (P less than .001) in serum glutamic oxalacetic transaminase (SGOT) was observed with time during the withdrawal period. Serum Cu decreased at 30-d withdrawal and increased thereafter (quadratic effect (P less than .05). Hepatic Cu-metallothionein levels increased 15-fold above control values in the litter-fed ewes (P less than .05).

Animal Feed↗
PubMed1983

Elevated manganese concentration and arginase activity in livers of streptozotocin-induced diabetic rats.

The regulation of hepatic arginase (EC 3.5.3.1) activity was studied in diabetic rats fed ad libitum. Arginase activity in liver cytosol increased 2 to 3 days after injection of streptozotocin into rats and remained elevated (maximally 1.7-fold) 13 days postinjection. Radioimmunoassays indicated, however, that the amounts of immunoreactive arginase protein in livers of control and diabetic rats were similar. The specific activity of purified preparations of arginase from diabetic rats was approximately 1.5-fold higher than that from control rats. Manganese, a cofactor for arginase, was elevated by 4 days post-streptozotocin injection and remained elevated (maximally 1.6-fold) for at least 13 days. Most of the manganese in control and diabetic liver cytosols was associated with macromolecules and eluted with arginase activity upon gel filtration. These data establish that the enhanced arginase activity observed in diabetes is coincident with elevated cofactor concentration but not with elevated enzyme protein concentration.

Animals↗
PubMed1983

Isolation and characterization of hepatic metallothionein from rainbow trout (Salmo gairdneri).

1. A low molecular weight (7,700) Zn- and Cu-containing protein was isolated from the livers of Zn-injected rainbow trout by gel filtration and ion exchange chromatography. Purity of the isolated protein was assessed by native and denaturing polyacrylamide gel electrophoresis and isoelectric focusing. 2. The purified protein was positively identified as a metallothionein on the basis of its molecular size, high metal content (3.6 g atoms Zn and 2.6 g atoms Cu per mole; 5.2% metal), heat stability, u.v. absorption spectrum, charge and amino acid composition (25% cysteine, no histidine and tryptophan, and trace tyrosine and phenylalanine). 3. The relatively high Cu content of this protein was unexpected and may be attributed to the presence of high levels of Cu, as Cu-thionein, in the livers of non-injected fish. 4. The comparative differences in the metal content of hepatic MT in trout and other animals are discussed.

Amino Acids↗
PubMed1983

Hepatic and renal metabolism of copper and zinc in the diabetic rat.

The influences of acute and chronic insulin-dependent diabetes on copper and zinc status of liver, kidney, and intestine were investigated in rats at 0-4 wk after streptozotocin (STZ) treatment. The concentration and the tissue contents of copper in liver and kidney were significantly elevated by 1 wk after STZ injection and increased thereafter, attaining levels two- and fivefold higher, respectively, than controls by 4 wk. Increased concentrations of zinc were also present in liver and kidney at 7 and 2 days after treatment, respectively, but zinc accumulated to a lesser degree than copper. In contrast, the concentration of copper and zinc in duodenum from control and all STZ-diabetic groups were similar. Increased and decreased quantities of copper and zinc were bound to metallothionein (MT) in liver and kidney, respectively, within 2 days after STZ injection. Thereafter, the quantities of both metals associated with MT increased with time in both tissues. Additional changes in zinc distribution in hepatic cytosol occurred prior to significant increases in the concentration of this metal in the tissue. The potential significance of altered trace metal metabolism during short-term changes in endocrine status and adverse effects of heavy metal accumulation during chronic hormonal imbalance are discussed.

Animals↗
PubMed1983

Zinc, iron, and copper absorption in the streptozotocin-diabetic rat.

Altered tissue levels of trace metals have been reported in streptozotocin-diabetic (STZ) rats. To determine whether increased hepatic and renal levels of Cu and Zn were associated with enhanced intestinal absorption, trace metal absorption was studied in control (C) and STZ rats using dietary balance and in situ ligated-loop techniques. The apparent daily absorption of dietary Zn and Cu per 100 g body wt was threefold higher in STZ than C rats. In comparison, dietary Fe absorption per day was not altered. Increased Zn absorption was closely correlated with diabetes-associated polyphagia. The initial rate of injected 65Zn excretion was more rapid in STZ rats, although the rate of excretion beyond day 7 was similar from C and STZ animals. The quantity of Zn, Fe, and Cu absorbed per 20 cm duodenal loop was similar for C and STZ rats. Zn, Fe, and Cu absorption per gram dry mucosa were reduced 45-53% in STZ rats due to the 50% increase in mucosal mass. Moreover, the quantity of radioisotopes accumulated per gram dry mucosa and the concentration of metallothionein per gram mucosal cytosol protein were similar in C and STZ animals. Together, these data demonstrate that increased absorption of dietary Zn and Cu is in part responsible for accumulation of these elements in STZ tissues and suggest altered metal transport at the luminal (brush border) surface of the intestinal epithelium.

Animals↗
PubMed1983

Depressed response of plasma iron and zinc to endotoxin and LEM in STZ-diabetic rat.

Laboratory and epidemiological evidence indicate that the enhanced flux of iron and zinc from the plasma to the storage compartments, such as liver, serves as a protective host response to combat infection. Studies were performed to determine the status of this nonspecific immune response in the diabetic animal, since it is commonly held that the diabetic has an increased incidence and susceptibility to infection. Normal rats and rats previously rendered diabetic by streptozotocin (STZ) were injected with either saline or Escherichia coli endotoxin, and plasma levels of zinc, iron, and copper were monitored 8 hr thereafter. Diabetic rats reduced their plasma zinc and iron levels by 35 and 25%, respectively, in response to endotoxin injection whereas control rats had a 70% decrease in zinc and a 46% depression in iron. Insulin administration to the diabetic rats restored the ability to decrease plasma zinc and iron to the same degree as control rats. Plasma copper did not change in any group. Further investigation suggested that the defect in trace metal response occurred after the secretion of leukocytic endogenous mediator (LEM) in the inflammatory response pathway. It is concluded that STZ-diabetic rats have a diminished ability to decrease plasma zinc and iron in response to endotoxin, and that this defect is due to an ineffective response of target tissues to the effects of leukocytic endogenous mediator. Furthermore, it is postulated that the hyperinsulinemia associated with the stress of infection functions to lower plasma zinc and, possibly, iron, thereby allowing the host to better combat infection.

Animals↗
PubMed1983

Pharmacokinetics of catalytically tritiated glycosaminoglycans in the rat.

Glycosaminoglycan mixture catalytically labelled with tritium gas (3H-GAG) was shown to have chemical characteristics and antithrombin-heparin cofactor activity in vitro similar to those of the native mixture of glycosaminoglycans (GAG). Rats were orally dosed with 3H-GAG in either aqueous solution or vegetable oil emulsion and the quantity of radioisotope absorbed assessed at various intervals. The quantity of 3H in plasma plateaued 8 h after dosing and remained near peak levels at least 16 h. Time dependent accumulation of the radioisotope within liver, spleen and testes was also observed.

Animals↗
PubMed1982

Identification of metallothionein in parenchymal and non-parenchymal liver cells of the adult rat.

Parenchymal and non-parenchymal cells were isolated from the livers of control, starved, Zn2+-injected and Cd2+-injected rats. Parenchymal cells were prepared by differential centrifugation after perfusion of the liver with collagenase. Non-parenchymal cells were separated from parenchymal cells by unit-gravity sedimentation and differential centrifugation. Yields of 2 x 10(8) non-parenchymal cells with greater than 95% viability and less than 0.2% contamination with parenchymal cells were obtained without exposing cells to Pronase. Metallothioneins-I and -II were identified in parenchymal cells and non-parenchymal cells from Zn2+-treated rats. The metallothionein contents of parenchymal cells, non-parenchymal cells and intact liver were quantified by a competitive 203Hg-binding assay. Administration of heavy-metal salts significantly increased the metallothionein content of both cell populations, although the concentration of the protein was approx. 2.5-fold greater in parenchymal cells than in non-parenchymal cells. Overnight starvation increased the metallothionein content of parenchymal cells without altering that of non-parenchymal cells. The potential significance of this differential response by different liver cell types with regard to the influence of Zn2+ on stress-mediated alterations in hepatic metabolism is discussed.

Animals↗
PubMed1982

Characterization of zinc-binding proteins of plasma in familial hyperzincemia.

Plasmas from three brothers (aged 35 to 45) with chronic hyperzincemia (325 to 525 micrograms/dl Zn) were analyzed and compared with pooled control plasma (104 microgram/dl Zn). The levels of copper, iron, total protein, albumin, and amino acids were similar in normal and hyperzincemic plasmas. Distribution of zinc among plasma components was determined chromatographically. Zinc eluted quantitatively in two distinct peaks from Sephadex G-100 gel filtration resin. The amount of the metal in fractions containing species larger than 100,000 molecular weight (peak I) was similar (35 to 45 micrograms/dl Zn) in normal and hyperzincemic plasmas. The additional complement of zinc in hyperzincemic plasma was localized within fractions containing zinc-binding proteins such as albumin, transferrin and HRG. That zinc was not associated with transferrin was determined by Affi-Gel affinity chromatography. The amounts of HRG in hyperzincemic plasmas were similar to or below those in control plasma. Zinc and albumin were selectively retained by anti-human albumin IgG coupled to protein A-Sepharose. In contrast, anti-human HRG IgG coupled to CM Bio-Gel A failed to bind plasma zinc. The findings indicate that (1) most available, protein-associated zinc in normal plasma is bound to albumin and (2) the additional complement of zinc in familial hyperzincemic plasma is associated with albumin. The biochemical basis for the enhanced binding of zinc by albumin in hyperzincemic plasma is unknown.

Adult↗
PubMed1981

Altered tissue content and cytosol distribution of trace metals in experimental diabetes.

An insulin-dependent diabetic condition was induced in male Sprague-Dawley rats by streptozotocin injection. Ten days after administration of the diabetogenic drug, tissue levels of copper, zinc, iron and manganese were determined and compared to control animals. Increased quantities of hepatic copper, zinc and manganese, renal copper and zinc and plasma zinc were observed in the diabetic group. Intestinal, muscle and spleen contents of the metals were similar in control and diabetic rats. Elevated levels of zinc- and copper-metallothionein were found in liver and kidney of diabetic rats. The distribution of zinc among soluble proteins in the diabetic liver was also content of tissues, intracellular distribution of zinc and the quantity of zinc-and copper-metallothionein to normal levels. Pair-feeding copper, zinc, iron and manganese to diabetic and control groups demonstrated that the enhanced food consumption of the diabetic rat was not a significant factor in the observed accumulation of trace metals in liver and kidney. These data suggest that the hormonal imbalance characteristic of the insulin-dependent diabetic condition influences trace metal metabolism. These studies also demonstrate the usefulness of the streptozotocin-diabetic rat as an animal model for investigations concerning hormone-mediated regulation of trace metal metabolism.

Animals↗
PubMed1979

Identification of albumin as the plasma carrier for zinc absorption by perfused rat intestine.

The isolated vascularly perfused rat intestine exhibits an obligatory need for a protein carrier in order to absorb zinc. Therefore this system is ideal for use as a model to identify the plasma carrier during zinc absorption. Affinity chromatography on Blue Sepharose CL-6B was employed to separate the major serum zinc-binding proteins in the portal effluent of the perfused intestine. It was found that 94% of newly absorbed 65Zn was transported in the portal serum-containing perfusate as an albumin-65Zn complex. The identity of albumin as the plasma carrier was confirmed by polyacrylamide-slab-gel electrophoresis. This evidence suggests that albumin is the plasma protein that is involved in removal of zinc from intestinal-mucosal cells and subsequent transport of the metal in portal blood to the liver.

Animals↗
PubMed1979

Cadmium accumulation and metabolism by rat liver parenchymal cells in primary monolayer culture.

Primary cultures of adult rat liver parenchymal cells, isolated by the collagenase perfusion technique and maintained as a monolayer, were used to investigate the characteristics of hepatic cadmium accumulation and metabolism. Cadmium accumulation was found to be a temperature- and concentration-dependent process that required sulfhydryl groups and was significantly stimulated by the addition of dexamethasone to the medium. Once taken up, cadmium was less available for exit-exchange processes than its biologically required congener, zinc. Moreover, cadmium influx enhanced zinc efflux. While most of the intracellular cadmium was located in the cytosol, its distribution within this fraction was altered with time. Initially the metal was bound to both high molecular weight species (less than 50 000) and metallothionein. As the incubation period increased, the cytosol concentration of cadmium and the percentage of this metal associated with metallothionein was likewise increased. [3H]Amino acid incorporation studies indicated that the accumulation of cadmium resulted in de novo synthesis of the 1 and 2 forms of metallothionein.

Amino Acids↗
PubMed1978

Degradation of rat liver metallothioneins in vitro.

The degradation of zinc and cadmium-induced hepatic metallothionineins was investigated in vitro. Both zinc-thionein and cadmium-thionein were labeled in vivo with [35S]cystine. The labeled proteins were isolated and purified by gel filtration and DEAE-ion exchange chromatography. Purified zinc[35S]thionein and cadmium-[35S]thionein were incubated with trypsin, chymotrypsin and pronase for varying times up to 24 h. The rate of degradation of zinc-thionein was twice that of cadmium-thionein when the proteins were incubated with trypsin. Virtually no digestion occurred when the proteins were incubated with chymotrypsin, whereas the rates of degradation were about equal when they were incubated with pronase. In contrast, degradation of zinc-thionein was twice that observed with cadmium-thionein when the proteins were incubated at pH 5.0 with a purified lysosomal extract. Degradation of these proteins by the lysosomal proteases was 77 and 46% within 3 h for zinc-thionein and cadmium-thionein, respectively. Thionein, the metal-free form of metallothionein, was degraded extremely rapidly by both neutral and lysosomal proteases. Chromatography of the digestion products on Sephadex G-25 demonstrated that all three forms of metallothionein were degraded to species of approximately 100-300 daltons. These data indicate that metals stabilize thionein polypeptides and suggest that the degradation of metallothionein in vivo is regulated in part by the species of metal bound.

Animals↗
PubMed1978

Zinc accumulation and metabolism in primary cultures of adult rat liver cells. Regulation by glucocorticoids.

Adult rat liver parenchymal cells were isolated by the collagenase perfusion technique and cultured as a monolayer for up to 20 h. The quantity of zinc accumulated from the extracellular environment was significantly increased by adding physiological concentrations of certain glucocorticosteroids to the medium. The degree of stimulation was directly related to glucocorticoid potency. Sex steroids, certain peptide hormones and prostaglandins E2 and F2alpha did not influence zinc accumulation. Control cells exhibited a decline of zinc accumulation after 4 h in culture although uptake processes were still operative. When dexamethasone, the most potent glucocorticoid used, was present in the medium the cells accumulated zinc at a linear rate greater than that seen in control cells, for at least 20 h. The dexamethasone-induced stimulation of zinc accumulation was relatively specific since 45Ca, 14C-labelled amino acids and [35S]cystine accumulation was not influenced by the hormone. A lag of 4 h was observed before an effect of dexamethasone on zinc accumulation could be detected. Moreover, the hormone-stimulated phase of accumulation was blocked when the cells were simultaneously incubated with either actinomycin D or cycloheximide. The additional complement of zinc accumulated by the dexamethasone-treated cells was localized in the cytosol fraction. Gel filtration and ion-exchange chromatography confirmed that this additional cytosol zinc was bound to metallothionein. [35S]Cystine was incorporated into metallothionein in hormone-treated cells indicating that the protein was synthesized de novo during periods of enhanced zinc accumulation.

Cells, Cultured↗
PubMed1978

Zinc uptake by isolated rat liver parenchymal cells.

Primary cultures of rat liver parenchymal cells maintained as a monolayer in serum-free culture medium were used to investigate the characteristics of zinc accumulation in vitro. Liver parenchymal cells accumulated zinc by a temperature-dependent, saturable process that was inhibited by cyanide, azide, oligomycin, N-ethylmaleimide and iodoacetamide. Cadmium reversibly inhibited zinc accumulation in both serum-free and serum-containing media. Gel filtration chromatographic studies showed that recently accumulated intracellular zinc was present as a low molecular weight complex smaller than metallothionein, the zinc storage protein, but larger than individual amino acids. The quantity of zinc accumulated was affected by preincubation of the cells with various hor?ONES. Dexamethasone, prednisone and prednisolone each increased zinc uptake by 40--50% when either insulin or glucagon was also present. Hydrocortisone, cortisone and sex steroids did not influence zinc accumulation. Removal of the polypeptide hormones from the medium abolished the stimulatory effect of the synthetic glucocorticoid steroid hormones on zinc accumulation.

17-Hydroxycorticosteroids↗
PubMed1978

Zinc absorption and metabolism by isolated, vascularly perfused rat intestine.

An isolated vascularly perfused rat intestine system was utilized to examine various aspects of zinc absorption in an attempt to more clearly examine the mechanisms involved. The lumen was perfused with a modified tissue culture medium containing 65Zn. The vascular system was perfused from the superior mesenteric artery to the portal vein, with Krebs-Ringer bicarbonate buffer containing 5% rat serum. The criterion for absorption was the amount of radioactivity transferred to the vascular perfusate. When the intestines were obtained from rats that had consumed a zinc-deficient diet the amount of zinc absorbed increased markedly. Conversely, elevation of zinc status decreased the amount of 65Zn that could be transferred to the vascular perfusate. These data strongly suggest that the isolated, perfused rat intestine retains the ability to exercise homeostatic control over 65Zn absorption. Transfer of infused 65Zn to the vascular perfusate was significantly decreased by aspirin, phytate, and prostaglandin E2. Uptake of 65Zn from the lumen into the intestinal cells was significantly increased by histidine and significantly decreased by phytate and prostaglandin E2. Thus, the isolated, vascularly perfused rat intestine appears to be capable of differentiating between the cellular uptake and cell to plasma transfer phases of zinc absorption.

Animals↗
PubMed1977

Cyclic accumulation of zinc by Candida utilis during growth in batch culture.

Intracellular accumulation of zinc by Candida utilis NRRL-Y-7634 was mediated by an energy-and temperature-dependent, highly specific process exhibiting saturation kinetics. In zinc-supplemented medium, uptake occured only during the lad and late-exponential phases; this type of transport did not occur with zinc in bacteria nor with iron in either yeast or bacteria. Cells of C. utilis did not possess a zinc-efflux system; they could reduce their level of intracellular zinc only by dilution of the metal into daughter cells. Zinc-deficient organisms accumulated 12 times more zinc than did cells of the same culture age grown in zinc-supplemented medium. The varied, but experimentally reproducible levels of intracellular zinc that occured in response to the physiological and environmental parameters had no detectable effects on respiration, rate of growth, total cell yield, or cell viability. Neither the mechanism underlying the cyclic accumulation of sinc nor the function of such behaviour are understood.

Biological Transport, Active↗