Relationship between copper, zinc and metallothionein in hepatocellular carcinoma and its surrounding liver parenchyma

BACKGROUND/AIM: Accumulation of copper (Cu) in hepatocellular carcinoma (HCC), especially in small tumors, is greater than that in the surrounding liver parenchyma. Metallothionein (MT) is considered to be present as Cu-MT, Zn,Cu-MT or Zn-MT. The aim of this study was to determine the presence and localization of Cu-MT and Zn-MT in HCC and surrounding liver parenchyma. METHODS: In 16 HCC patients, surgically resected specimens including HCC and surrounding liver parenchyma were evaluated. RESULTS: The level of Cu present in small HCC (<4 cm in diameter) was significantly greater than that in the surrounding liver parenchyma (p<0.05). However, the level of Cu in large HCC (>4 cm in diameter) was similar to that in the surrounding liver parenchyma. Analysis by Sephadex G-75 gel filtration revealed that the peak fraction due to Cu was identical to that due to MT in 14 (87.5%) of 16 HCC, the peak fraction due to Cu and Zn was identical to that due to MT in 2 (12.5%) HCC, and the peak fraction due to Zn was identical to that of MT in none of 16 HCC. CONCLUSIONS: Accumulation of Cu in small HCC, in which Cu was present as Cu-MT or Zn, Cu-MT, was greater than that in the surrounding liver parenchyma. Cu accumulation and the presence of MT in the liver may be related to carcinogenesis of HCC, because of the similarity of these findings in the experimental data of Long-Evans rats with a cinnamon-like coat color who develop HCC spontaneously.     

Metals and the liver in Alzheimer's disease. An investigation of hepatic zinc, copper, cadmium, and metallothionein

Significant alterations of tissue metal levels have been reported in Alzheimer's disease (AD). Because the liver is intimately involved in metabolism and storage of metals, it may provide a useful site for study of these metals in AD. This study compares livers in AD and controls in their concentrations of zinc, copper, cadmium, and metallothionein, a metal-binding protein important in regulation of metal metabolism. Liver tissue was obtained from 17 patients with AD and 17 age- and sex-matched controls within 12 hours of death and stored at -70 degrees C. Neuropathologic confirmation of diagnosis was available in all cases. Liver homogenates (20%) were used for metal analysis by atomic absorption spectroscopy after wet digestion. Cytosolic metallothionein levels were quantitated by the cadmium or silver saturation method. A significant decline in body and liver weight was found in patients with AD, with no significant change in liver protein or DNA concentration. Total hepatic cadmium (P less than .001) and zinc (P less than .030) concentrations were significantly elevated in AD. The Sephadex G75 chromatographic profile was altered in AD with reduction in zinc bound to metallothionein fractions and increased binding to high molecular weight fractions. These data suggest that the metabolism of cadmium and zinc is altered in AD.     

Serum levels of zinc, copper and selenium in patients with Wilson's disease treated with zinc

Zinc administered on a long-term basis in excess to patients with Wilson a disease blocks in a significant way copper absorption from the gut, prevents its accumulation and toxic action in the organism. The authors investigated the effect of its long-term administration on the plasma concentration of copper, zinc, and selenium, on the superoxide dismutase activity in red blood cells and glutathione peroxidase activity in whole blood. In seven patients with Wilson a disease treated with zinc sulphate, 136 mg of elemental zinc for 1.5 years (18 months), the authors assessed the plasma concentration of zinc, copper, selenium and ceruloplasmin, the activity of superoxide dismutase in red blood cells, the activity of glutathione peroxidase in whole blood and the urinary excretion of zinc and copper in 24 hours. Envisaged findings with regard to the diagnosis of the investigated patients and their treatment: elevated plasma zinc concentration and increased urinary excretion, reduced copper and ceruloplasmin plasma concentration and increased urinary copper excretion. The authors recorded also a significantly elevated selenium plasma concentration and a significantly higher concentration of superoxide dismutase in red blood cells (p < 0.05). The increase of the glutathione peroxidase activity in whole blood in the investigated patients was not significant (p < 0.05). Changes in the values of the investigated parameters in patients with Wilson s disease treated on a long-term basis with zinc indicate the possible mutual interaction of zinc with other trace elements with an impact on the activity of the corresponding metalloenzymes, i.e. in the sphere in antioxidant systems.     

Design and synthesis of deoxynucleic guanidine: a polycation analogue of DNA.

The basic strategy is described for the connection of nucleosides by guanidinium (g) linkers to provide the positively charged deoxynucleic guanidine putative antigene agents. The synthetic procedures are provided for d(gT)n. Molecular modeling of double-stranded [d(gT)10.d(Ap)10] and the triple-helical hybrids [d(Tp)10.d(Ap)10.d(gT)10] and [d(gT)10.d(Ap)10.d(gT)10] suggest modes of interaction and anticipated structural features.     

Aldophosphamide: synthesis, characterization, and comparison with "Hohorst's aldophosphamide".

Synthesis of aldophosphamide was attempted by many standard aldehyde-forming reactions under a variety of conditions. Trace amounts of aldophosphamide were produced in several of the reactions, as judged by mass-spectral evidence. A stabilized derivative, aldophosphamide semicarbazone, was prepared and characterized by infrared and proton magnetic resonance, and mass spectral analysis) of "Hohorst's aldophosphamide" failed to reveal any evidence for the existence of an aldehyde moiety, and thin-layer chromatographic comparison with the synthetic analogs diethylaldophosphamide and diethylhomoaldophosphamide indicated radical differences in migration rates between those of the analogs and that of "Hohorst's aldophosphamide." It is suggested that "Hohorst's aldophosphamide" is perhaps a diastereoisomer of 4-hydroxycyclophosphamide or an aldehyde hydrate or hemiacetal with 1,3-propanediol.     

A thyroid hormone analogue, triiodothyroacetic acid, corrects corticosteroid-downregulated collagen synthesis.

The aim of this study was to compare the change in collagen synthesis between topical treatments with two doses of triiodothyroacetic acid (TRIAC), a thyroid hormone analogue, and placebo, after pretreatment with topical betamethasone 17-valerate (BM). Eighteen healthy volunteers were pretreated with BM on abdominal skin for 3 days, and were then treated for 14 days with a cream containing TRIAC (0.03% or 0.1%) or a placebo cream. Collagen production was assessed by quantifying the amino terminal propeptides of human type I and type III procollagen (PINP and PIIINP) in fluids from suction-induced blisters on the treated skin. Three days of treatment with BM led to an average reduction of PINP of 70% and of PIIINP of 50%. Seven days after treatment, the median increase in PINP was 230% (p = 0.03) in the Triac 0.03% group, 148% (p = 0.2) in the TRIAC 0.1% and 5% in the placebo group. The median increase in PINP in the skin area from the start of treatment to the end of treatment was 521% (p = 0.06) in the TRIAC 0.03% group, 339% (p = 0.2) in the TRIAC 0.1% group, and 55% in the placebo group (the p values are related to baseline). Seven days after treatment, the median increase in PIIINP was 24% (p = 0.6) in the Triac 0.03% group, 23% (p = 0.6) in the TRIAC 0.1% group, and -12% in the placebo group. The median increase in PIIINP in the skin area from the start of treatment to the end of treatment was 137% (p = 0.7) in the TRIAC 0.03% group, 230% (p = 0.9) in the TRIAC 0.1% group and 58% in the placebo group (the p values are related to baseline). Histologic examinations of sections from punch biopsies taken at the end of the treatment showed more thickened collagen fibers and increased density of PINP-producing dermal fibroblasts in the TRIAC groups compared to the placebo group. The result suggests a potential role for TRIAC-containing cream concomitant with anti-inflammatory topical treatment with potent glucocorticoids to prevent their suppressive activity on dermal collagen production.     

Crosslinked myosin subfragment 1: a stable analogue of the subfragment-1.ATP complex.

Myosin subfragment 1 (S-1) with its two reactive cysteine groups crosslinked by N,N'-p-phenylenedimaleimide (pPDM), is shown to be a stable analogue of S-1 X ATP and S-1 X ADP X Pi, the predominant complexes present during the steady-state hydrolysis of ATP by S-1. pPDM-S-1 binds to actin with about twice the affinity of S-1 X ATP or S-1 X ADP X Pi, whereas its affinity is 1/100th of that of S-1 X 5'-adenylyl imidodiphosphate and 1/1,000th of that of S-1 X ADP. pPDM-S-1 is also similar to S-1 X ATP and S-1 X ADP X Pi in that its binding to actin is not inhibited by troponin-tropomyosin. In contrast, the binding of S-1, S-1 X ADP, and S-1 X 5'-adenylyl imidodiphosphate to actin is markedly inhibited by troponin-tropomyosin in the absence of Ca2+ when actin is in large excess over S-1. This suggests that modifying S-1 with pPDM stabilizes a conformation which mimics that induced by the binding of ATP.     

Gene synthesis, expression, and mutagenesis of the blue copper proteins azurin and plastocyanin.

Genes for the blue copper proteins Populus nigra var. italica plastocyanin and Pseudomonas aeruginosa azurin have been constructed by a stepwise procedure. The leader sequence for azurin has been placed before the genes directing plastocyanin and azurin transport to the periplasmic space when the genes are expressed in Escherichia coli. Site-saturation mutagenesis has been used to alter two copper-binding residues of azurin (Met-121 and His-46) and Met-92 of plastocyanin. While the plastocyanin mutants do not appear to bind copper, the azurin variants all bind copper and show characteristic type I blue copper centers. In particular, the electronic spectra reflect the dominance of the charge transfer interaction between copper and the thiolate of Cys-112, being relatively insensitive to changes in Met-121 or His-46. In contrast, removal of Met-121 appreciably alters the EPR spectra of the mutants, although, to a first order, the spectra of all mutants are themselves similar, suggesting a more distorted geometry around copper in the mutants than in the wild type.     

Efficient synthesis of human type alpha transforming growth factor: its physical and biological characterization.

Human transforming growth factor type alpha (TGF-alpha) was synthesized by a stepwise solid-phase method with an overall yield of 26%. Synthetic TGF-alpha, consisting of 50 amino acid residues deduced from a cDNA precursor sequence, was purified in a single HPLC step. The homogeneity and primary structure were confirmed by several criteria including Edman degradation and mass spectrometry. Synthetic TGF-alpha was as active as murine epidermal growth factor in binding to the epidermal growth factor receptor and in stimulation of anchorage-dependent and of anchorage-independent growth of normal indicator cells in culture. Synthetic TGF-alpha stimulated plasminogen activator production in A 431 and HeLa cells; the stimulation was similar to that induced by epidermal growth factor. Furthermore, synthetic human TGF-alpha showed similar immunoreactivity when compared with rat TGF-alpha. Thus, the 50-amino acid TGF-alpha is likely to be the bioactive principle produced and secreted by tumor cell lines.     

Zinc, iron, copper, selenium, lactoferrin, and ferritin in human pus

BACKGROUND: Restriction of zinc and iron available for microbial growth in tissues are well-recognized host defense mechanisms. The present studies were performed to characterize some constituents of human pus that may affect these important host defenses. METHODS: Zinc, iron, copper, calcium, and magnesium in pus were measured using an atomic absorption spectrophotometer; selenium was measured fluorometrically. Ferritin was measured with a fluorometric enzyme immunoassay, and lactoferrin was measured with a radial diffusion assay. The growth of Escherichia coli at 37 degrees C was measured in pus supernate adjusted to pH 5.5 or 7.4, in boiled supernate, or in supernate adjusted with 1.3 mM iron or 0.9 mM zinc singly or together. RESULTS: Zinc and iron concentrations in pus exceeded normal serum. Calcium and magnesium levels were 2- to 3-fold lower and higher, respectively, than normal serum values. Lactoferrin concentrations of were 880 +/- 48 microg/mL and ferritin levels were 20,726 +/- 2,667 ng/mL. Growth of an E coli strain was inhibited in pus at pH 5.5 but not at pH 7.4, and growth was enhanced by addition of iron or zinc to E coli suspended in pus at pH 6.7. CONCLUSIONS: To our knowledge, this is the first report of the zinc, iron, copper, selenium, lactoferrin, and ferritin levels of human pus. These studies provide additional insight into host defense mechanisms mediated by the restriction of the bioavailability of zinc and iron in suppurative infection.     

Betadoublet: de novo design, synthesis, and characterization of a beta-sandwich protein.

How an amino acid sequence encodes the information necessary for a protein to adopt a unique tertiary structure remains unresolved. We are addressing this problem by designing "from scratch" protein molecules that will adopt predetermined three-dimensional structures. Based on this strategy, two identical four-stranded beta-sheets were designed to dimerize and form a beta-sandwich protein, called betadoublet. A synthetic gene encoding half the beta-sandwich protein was expressed in Escherichia coli, and the protein was purified to homogeneity. Biophysical characterization of betadoublet in aqueous solution demonstrated that the disulfide formed between the two sheets and that the dimer was a compact unaggregated globular protein, consisting predominantly of beta-sheet and stable to thermal denaturation. It has some backbone amide protons whose exchange is slow enough to be measured by NMR but binds more of the dye 1-anilinonaphthalene-8-sulfonate than a well-folded protein.     

Gonadotropin-releasing peptide from human follicular fluid: isolation, characterization, and chemical synthesis.

A gonadotropin-releasing peptide has been isolated from human follicular fluid. Its amino acid composition and sequence are completely different from the hypothalamic lutropin-releasing hormone. It is designated human follicular gonadotropin-releasing peptide and abbreviated as hF-GRP. The primary structure of this peptide (H-Thr-Asp-Thr-Ser-His-His-Asp-Gln-Asp-His-Pro-Thr-Phe-Asn-OH) has been confirmed by chemical synthesis. In the mouse pituitary incubation assay, the ED50 value for follitropin or lutropin release is estimated to be 1.2-1.6 nM.     

Cardiolipin: a stereospecifically spin-labeled analogue and its specific enzymic hydrolysis.

The spin-labeled cardiolipin 1-(3-sn-phosphatidyl)-3-[1-acyl-2-(16-doxylstearoyl)glycero(3)phosphol]-sn-glycerol has been prepared. The stereoselective synthesis makes use of the monolysocardiolipin 1-(3-sn-phosphatidyl)-3-[1-acyl-2-lyso-sn-glycero(3)phospho]-sn-glycerol, available from the stereospecific hydrolysis of cardiolipin by phospholipase A2 (phosphatide 2-acylhydrolase, EC 3.1.1.4) of Trimeresurus flavoviridis. The results of treatment of the spin-labeled cardiolipin with the cardiolipin-specific phospholipase D (phosphatidylcholine phosphatidohydrolase, EC 3.1.4.4) (Hemophilus parainfluenzae) of known specificity and with phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) of Bacillus cereus are consistent with the assigned structure. The spin-labeled cardiolipin is further characterized and the unique features of this diastereomer are discussed in the context of the unusual stereochemistry of the natural phospholipid.     

Structural characterization of the Get4/Get5 complex and its interaction with Get3

The recently elucidated Get proteins are responsible for the targeted delivery of the majority of tail-anchored (TA) proteins to the endoplasmic reticulum. Get4 and Get5 have been identified in the early steps of the pathway mediating TA substrate delivery to the cytoplasmic targeting factor Get3. Here we report a crystal structure of Get4 and an N-terminal fragment of Get5 from Saccharomyces cerevisae. We show Get4 and Get5 (Get4/5) form an intimate complex that exists as a dimer (two copies of Get4/5) mediated by the C-terminus of Get5. We further demonstrate that Get3 specifically binds to a conserved surface on Get4 in a nucleotide dependent manner. This work provides further evidence for a model in which Get4/5 operates upstream of Get3 and mediates the specific delivery of a TA substrate.     

Metal ions induce expression of metallothionein in pancreatic exocrine and endocrine cells

Northern blot hybridization established that metallothionein (MT) mRNA levels were dramatically elevated in the rat pancreas following injection of Cd or Zn salts. To determine which pancreatic cell types express the MT gene, Northern blot hybridization analysis of RNA from preparations enriched for acini, in situ hybridization, and immunocytochemistry were used. RNA from pancreatic acini of Zn-treated rats contained high levels of MT mRNA. In control rats, in situ hybridization suggested very low levels of MT mRNA in both exocrine and endocrine cells in the pancreas, but these levels were dramatically increased in both these cell populations following metal injection. In contrast, levels of insulin-I mRNA in the endocrine cells were not affected by metal injection. A similar result with MT mRNA was obtained in mouse and chicken pancreas using Northern blot and in situ hybridization. Immunocytochemistry detected MT in the rat acinar cell cytoplasm following metal injection. Although inconsistent with in situ hybridization studies and immunocytochemical analysis of exocrine cells, immunocytochemistry for MT indicated a uniform staining pattern of islet cells that was unaffected by metal treatment. These results establish that metal ion induction of the MT genes in pancreas occurs in both endocrine and exocrine cells, which suggests that this protein has diverse physiologic functions in this organ.