Substantivity of zinc salts used as rinsing solutions and their effect on the inhibition of Streptococcus mutans

The antimicrobial efficacy of zinc (Zn) salts (sulfate and acetate) against Streptococcus mutans (S. mutans) present in the oral cavity was tested in this study. The substantivity of Zn salts was assessed by determining the concentration of Zn in whole, unstimulated saliva and by measuring the magnitude of suppression of salivary S. mutans, 2h after rinsing. The concentration of Zn was measured by atomic absorption spectrometry (AAS) with electrothermal atomization (ET AAS) in saliva sampled before (basal) and 24h after mouth rinsing with different concentrations of Zn (0.1%, 0.5% and 1%) administrated as sulfate and acetate. The estimation of Zn levels in samples collected 30, 60, 90 and 120 min after rinsing was carried out by AAS with flame atomization (FAAS). Immediately after rinsing, the concentration of Zn in saliva sharply increased with respect to the baseline values (0.055+/-0.017 mg/L), followed by a sustained decrease, probably due to clearance of salivary flow or swallowing during sampling. A significant reduction (>87%) in the total mean S. mutans counts was found 2h after rinsing either with sulfate or acetate solutions, as evidence of the high substantivity and effectiveness of the Zn salts tested. A statistically significant inverse relationship (p<0.001 and the Pearson correlation coefficients between -34% and -50%) was found between Zn levels and the respective pH values measured in the samples collected 60 and 120 min after rinsing, sustaining the theory of bacterial glycolysis inhibition.     

Trace element transfer from alginate dressings to wounds

ABSTRACT

A method has been developed for impregnating alginate-based wound dressings with trace elements required for wound healing and for quantifying the transfer from these dressing to wound fluid (for which a substitute—blood serum—was used in these experiments). Under ideal conditions, up to 85% can be carried across from the tow to the wound fluid.     

Application of PIXE analysis to the study of the regional distribution of trace elements in normal human brain

A particle-induced X-ray emission (PIXE) analysis method is presented, which allows measurement of eight elements (i.e., K, Ca, Mn, Fe, Cu, Zn, Se, and Rb) in human brain samples of only a few mg dry weight. The precision and accuracy of the method were investigated by analyzing animal brain matter with both PIXE and instrumental neutron activation analysis (INAA). The method was applied to measure the 8 elements in 46 different regions of 3 human brains. The sections analyzed originated from either the left or the right cerebral hemisphere, brain stem, and cerebellum. For one of the brains, sections were also analyzed from 26 corresponding regions of both hemispheres. For all elements, similar concentrations were found in the corresponding areas of the left and right sides of the brain. The concentrations (in μg/g dry weight) of the elements K, Fe, Cu, Zn, Se, and Rb were consistently higher in cortical structures than in white matter. Deep nuclei and brain stem, which have a mixed composition, showed intermediate values for K, Zn, Se, and Rb. A hierarchical cluster analysis indicated that the various brain regions clustered into two large groups, one comprising gray and mixed matter regions and the other, white and mixed matter brain areas.     

Effects of essential divalent metals on carcinogenicity and metabolism of nickel and cadmium

Interactions between the physiologically essential metals calcium, magnesium, and zinc and the carcinogenic metals nickel and cadmium were investigated to help elucidate the mechanisms of action of the carcinogenic metals. Bioassay studies revealed several significant findings, including: (1) the ability of magnesium and calcium to inhibit nickel-induced elevation of pulmonary adenoma incidence in strain A mice; (2) the ability of magnesium, but not of calcium, to prevent cadmium-induced subcutaneous sarcoma formation; and (3) the ability of magnesium, but not of calcium, to inhibit nickel-induced muscle tumor formation. Biochemical studies indicated a direct relationship between the antitumorigenic potential of magnesium and the capacity of this metal to: (1) inhibit nickel and cadmium uptake by the target tissues in vivo; (2) inhibit nickel-induced disturbances in DNA synthesis in vivo; (3) inhibit nuclear and cytosolic uptake of nickel by the target tissue cells in vivo; and (4) inhibit nickel and cadmium binding to DNA in vitro. Calcium, which in most cases did not prevent carcinogenesis, had no consistent influence on the uptake of carcinogenic metals or their biochemical effects in the target tissues. Magnesium and zinc, but not calcium, were also found to attenuate the acute toxic effects of nickel, indicating a possible correlation between prevention of acute effects and reduction in tumorigenicity. Zinc, which antagonizes cadmium tumorigenicity in the rat testis, was found to reduce markedly cadmium uptake into isolated testicular interstitial cells. Also, zinc was found to inhibit strongly cadmium binding to DNA in vitro.     

A comparative study of the soil zinc fractions determined by chemical methods and electro-ultrafiltration (EUF) and their relations to zinc nutrition in rice

Rice (IR 42) was grown on two soils differing in zinc status for 30 days with and without Zn under submerged conditions in pots. The fate of soil zinc was characterized by extraction of the soil successively with copper acetate and sodium hypochlorite and by EUF extraction. Most of the applied zinc was extracted by copper acetate and represented as complexed fraction. There exists a close and significnat relation between Cu(OAc)₂-extractable zinc and Zn extracted by EUF for 5 minutes at 50 volts (r=0.98). The EUF-extractable zinc and Cu(OAc)₂-extractable zinc were significantly correlated with the zinc content in the plant (r=0.82). The data from this investigation suggest the possibility of Zn fractionation with the EUF technique and the fractions obtained agree closely to those determined by chemical methods. The results obtained indicate that Zn in soil is held by weak organic bonding and that the extractions by Cu(OAc)₂ and/or EUF-5 minutes serve as a useful basis for extimating zinc availability in rice soils.     

Induction of hepatic metallothionein by salicylate in adult rats

Application of salicylate increased the concentration of metallothionein (MT) in liver of pregnant rats as well as of adult male rats, whereas in fetal liver, MT was reduced by salicylate. Induction of MT synthesis by salicylate is an indirect effect because in cultured hepatocytes salicylate did not induce MT synthesis. Salicylate increased MT also in adrenalectomized rats. Indomethacin induced the same concentration of MT in maternal liver as salicylate. However, indomethacin had no effect on MT in fetal liver. Induction of MT in adult liver by salicylate and indomethacin was independent of zinc.     

锌和铜在生长抑素对链佐霉素引起的胰岛B细胞损伤的保护中的作用

我们以前的工作指出,生长抑素可以预防链佐霉素对大鼠胰岛B细胞的损伤。本工作测定给药前后大鼠血清和组织中Zn、Cu含量,以进一步观察链佐霉素破坏大鼠胰岛B细胞后生长抑素预防效应的可能机制。结果为:链佐霉素(STZ)(35mg/kg,ip)注射后24h的大鼠,血清Zn浓度下降,Cu浓度升高,Zn/Cu比值倒置;用生长抑素作预防性注射后,血清Zn浓度与正常对照水平相同,Cu浓度虽稍有升高,但Zn/Cu比值正常。保护组的血清Zn与损伤组比较,差异极为显著。两组的Zn/Cu比值同样也具有显著差异。在给药后72h,血清Zn/Cu比值在各组之间仍呈上述关系,但差异减小。在大鼠胰腺,注射链佐霉素后胰腺组织Zn浓度未见改变,但生长抑素作预防性注射可使组织锌含量增加。上述结果提示,在生长抑素对胰岛B细胞的保护机制中可能有Zn和Cu的参与。预防性注射生长抑素所引起的高Zn状态可能有利于机体细胞含Zn酶类的活性,增强已损伤细胞的修复。     

Long-term effects of lactational zinc deficiency on bone mineral composition in rats fed a commercially modified Luecke diet

The purpose of this study was threefold: 1. to determine the long-term effects of interactions between lactational zinc deficiency and gender on bone mineral composition in repleted rat offspring, 2. to determine the nutritional efficacy of the second of two commercially designed, modified Luecke diets (ML2) during the gestational and lactational stress, and 3. determine the ultratrace element contents of Ralston Rodent Laboratory Chow #5001. The ML2 basal diet, based on dextrose, sprayed egg white, and corn oil contained 0.420 μg Zn/g, was supplemented with Zn (as zinc acetate) at 0 (diet 0ML2) or 30 (diet 30ML2) μg/g, and was mixed and pelleted commercially. all rat dams were fed the 30ML2 diet ad libitum during gestation. Beginning at parturition, the dams were fed either the 1. 0ML2, 2. 30ML2 (food restricted), or 3. 30ML2 (ad libitum) diets. All pups were fed the 30ML2 diet ad libitum from 23 to 40 d of age. From d 40 to 150, all pups were fed Ralston Rodent Laboratory Chow. The 30ML2 diet was found to be nutritionally efficacious; litter size and pup growth were normal and pup mortality was only 1.2%. Pups (ZD) with access to the 0ML2 diet until 23 d of age and nursed by dams fed the 0ML2 diet, when compared to pups (PF) fed restricted amounts of the 30ML2 diet, exhibited increased mortality and decreased concentrations of tibial zinc but no change in growth. Inadequate zinc nutriture during infancy, despite postlactational zinc repletion, induced imbalances in adult bone mineral metabolism. Thus, at 150 d of age, the ZD pups exhibited increased levels of bone P and Mg and decreased concentrations of K as compared to the PF pups.