Two mechanisms of oral malodor inhibition by zinc ions

Abstract Objectives The aim of this study was to reveal the mechanisms by which zinc ions inhibit oral malodor. Material and Methods The direct binding of zinc ions to gaseous hydrogen sulfide (H2S) was assessed in comparison with other metal ions. Nine metal chlorides and six metal acetates were examined. To understand the strength of H2S volatilization inhibition, the minimum concentration needed to inhibit H2S volatilization was determined using serial dilution methods. Subsequently, the inhibitory activities of zinc ions on the growth of six oral bacterial strains related to volatile sulfur compound (VSC) production and three strains not related to VSC production were evaluated. Results Aqueous solutions of ZnCl2, CdCl2, CuCl2, (CH3COO)2Zn, (CH3COO)2Cd, (CH3COO)2Cu, and CH3COOAg inhibited H2S volatilization almost entirely. The strengths of H2S volatilization inhibition were in the order Ag+ > Cd2+ > Cu2+ > Zn2+. The effect of zinc ions on the growth of oral bacteria was strain-dependent. Fusobacterium nucleatum ATCC 25586 was the most sensitive, as it was suppressed by medium containing 0.001% zinc ions. Conclusions Zinc ions have an inhibitory effect on oral malodor involving the two mechanisms of direct binding with gaseous H2S and suppressing the growth of VSC-producing oral bacteria.

Analysis on Interaction between Human Serum Albumin and Zinc Ions by Circular Dichroism and Isothermal Titration Calorimetry / 世界科学技术-中医药现代化

This article was aimed to study the mechanism of interaction between human serum albumin (HSA) and zinc ions, in order to provide the information on the secondary structure modification of HSA and the thermodynamics parameters using circular dichroism (CD) and isothermal titration calorimetry (ITC). CD and ITC were applied in the study. The concentration of HSA were 0.025 mmol·L-1, 0.05 mmol·L-1, 0.1 mmol·L-1, and 0.2 mmol·L-1, respectively. The concentration of zinc ion was 5 mmol·L-1. The CD analysis revealed that the secondary structure modification of HSA differed depending on the concentration of HAS. And the content ofα-helix was inversely proportional to the concentration of HSA. When the concentration of HSA was 0.2 mmol·L-1, the content ofα-helix was special. A series of thermodynamics parameters including association constants (Kb), stoichiometry (N), entropy (ΔS) and enthalpy (ΔH) were investigated by ITC analysis. And two types of binding sites were observed when ZnSO4(mmol·L-1)?HSA (mmol·L-1)= 5?0.2. The secondary structure modification of HSA interacting with zinc ions depended on the concentration of HSA, a dramatic reduction ofα-helix was detected when the concentration of HSA attained 0.2 mmol·L-1. And the protein hydrophobicity reduction and peptide chains expansion were equally observed at this concentration. The ITC analysis also revealed endothermic and exothermic binding sites in the ZnSO4-HSA interaction when ZnSO4 (mmol·L-1)?HSA (mmol·L-1)= 5?0.2, indicating that the endothermic sites were specific but not preferential for zinc ions interactions. These results provided theoretical supports for the application of Zn2+ to open the endothermic sites of HSA.

Zinc ions improve the stability of titanium implants under the condition of osteoporosis / 中国组织工程研究

BACKGROUND:Zinc can improve bone reaction to titanium implants through regulation of osteoblast activity under the condition of osteoporosis. OBJECTIVE:To study the zinc ions effect on improving the stability of titanium implants under the condition of osteoporosis. METHODS:After removal of the ovary, 28 female Sprague-Dawley rats presented with osteoporosis symptoms for 12 weeks and then, they were randomly divided into two groups. Two kinds of titanium implants with (experimental group) or without zinc (control group) were inserted into the bilateral femoral metaphysis longitudinal y in the ovariectomized rats, separately. Three rats were selected from each group for double fluorescence labeling examination. Mineral apposition rate was calculated at postoperatively 6 weeks. Another four rats were selected from each group for histomorphometry analysis at postoperatively 12 weeks. Biomechanical test was in the remaining rats in the two groups to calculate the maximum push-out force and maximum shear force at 12 weeks postoperatively. RESULTS AND CONCLUSION:The double fluorescence labeling examination revealed that the mineral apposition rate was improved in the experimental group as compared with the control group (P<0.05). New bone formation occurred in the two groups. However, larger new bone amount, higher bone area ratio and bone-to-implant contact were detected in the experimental group (P<0.05 or P<0.01). The maximum push-out force and maximum shear force were also superior in the experimental group to the control group (P<0.05 or P<0.01). These findings indicate that zinc ions are capable of promoting bone formation and improving implant fixation in ovariectomized rats.

Influences of DTC and zinc supplementation on the cellular response restoration in restrained mice

The studies were conducted on Balb/c mice exposed to restraint stress twice for 12 h at 24 h intervals. Prior to restraint stress the mice were treated with sodium diethyldithiocarbamate (DTC) i.p. at a dose of 20 mg/kg five times at 48 h intervals. DTC was used per se or with zinc ions interaction, by adding zinc sulfate to drinking water at a dose of 72 microgram/mouse daily. The results obtained in the study show that restraint stress causes involution of lymphatic organs, decreased the percentage of immature (CD4+CD8+) and, mature (CD4+) thymocytes and CD4+, CD8+and CD19 + splenocytes and proliferative response of thymocytes stimulated in vitro with concanavalin A (Con A) and phytohemagglutinin (PHA). The restraint stress decreased also interleukin-1 (IL-1) production by murine intraperitoneal macrophages stimulated in vitro with lipopolysaccharide (LPS) from E. coli. Pretreatment with DTC counteracted restraint stress-induced immunosuppression, which is expressed as partial normalisation of the total number of thymocytes, splenocytes and IL-1 production, accelerated regeneration of thymus and spleen, shorter suppressive action of restraint stress on the percentage of CD4+CD8+thymocytes and in total normalisation of the CD4+thymocytes and splenocytes. DTC administered prior to restraint stress augmented the proliferative response of thymocytes to two mitogens. The immunocorrecting action of DTC is enhanced by zinc supplementation, expressed in the increased percentage of CD4+thymocytes and splenocytes, CD19 + splenocytes, proliferative activity of thymocytes stimulated with PHA and IL-1 production. The obtained results show that DTC administration can be supplemented with zinc in order to restore the immune system impaired by stress.