0
selected
-
1.
A comparative analysis of metal allergens associated with dental alloy prostheses and the expression of HLA-DR in gingival tissue.
Zhang, X, Wei, LC, Wu, B, Yu, LY, Wang, XP, Liu, Y
Molecular medicine reports. 2016;(1):91-8
-
-
Free full text
-
Abstract
The present study aimed to provide guidance for the selection of prosthodontic materials and the management of patients with a suspected metal allergy. This included a comparison of the sensitivity of patients to alloys used in prescribed metal‑containing prostheses, and correlation analysis between metal allergy and accompanying clinical symptoms of sensitized patients using a patch test. The results from the patch test and metal component analyses were processed to reach a final diagnosis. In the present study, four dental alloys were assessed. Subsequent to polishing the surface of a metal restoration, the components were analyzed using an X‑ray fluorescence microscopy and spectrometry. Immunohistochemical analysis, reverse transcription‑polymerase chain reaction and western blotting were used to detect the expression levels of human leukocyte antigen (HLA)‑DR in gingival tissues affected by alloy restoration, and in normal gingival tissue samples. Positive allergens identified in the patch test were consistent with the components of the metal prostheses. The prevalence of nickel (Ni) allergy was highest (22.8%), and women were significantly more allergic to palladium and Ni than men (P<0.05). The protein and gene expression levels of HLA‑DR in the Ni‑chromium (Cr) prosthesis group were significantly higher, compared with those in the other groups (P<0.01); followed by cobalt‑Cr alloy, gold alloy and titanium alloy. In conclusion, dentists require an understanding of the corrosion and allergy rates of prescribed alloys, in order to reduce the risk of allergic reactions. Patch testing for hypersensitive patients is recommended and caution is required when planning to use different alloys in the mouth.
-
2.
Primary endpoint results of the OMEGA Study: One-year clinical outcomes after implantation of a novel platinum chromium bare metal stent.
Wang, JC, Carrié, D, Masotti, M, Erglis, A, Mego, D, Watkins, MW, Underwood, P, Allocco, DJ, Hamm, CW
Cardiovascular revascularization medicine : including molecular interventions. 2015;(2):65-9
Abstract
BACKGROUND/PURPOSE Bare metal stents (BMS) have similar rates of death and myocardial infarction (MI) compared to drug-eluting stents (DES). DES lower repeat revascularization rates compared to BMS, but may have higher rates of late stent thrombosis (ST) potentially due to impaired endothelialization requiring longer dual anti-platelet therapy (DAPT). OMEGA evaluated a novel BMS designed to have improved deliverability and radiopacity, in comparison to currently available platforms. METHODS/MATERIALS OMEGA was a prospective, multicenter, single-arm study enrolling 328 patients at 37 sites (US and Europe). Patients received the OMEGA stent (bare platinum chromium element stent) for the treatment of de novo native coronary artery lesions (≤28 mm long; diameter ≥2.25 mm to ≤4.50mm). The primary endpoint was 9-month target lesion failure (TLF: cardiac death, target vessel-related MI, target lesion revascularization [TLR]) compared to a prespecified performance goal (PG) based on prior generation BMS. All major cardiac events were independently adjudicated. DAPT was required for a minimum of 1 month post procedure. RESULTS In the OMEGA study, the mean age was 65; 17% had diabetes mellitus. The primary endpoint was met; 9 month TLF rate was 11.5%, and the upper 1-sided 95% confidence bound of 14.79% was less than the prespecified PG of 21.2% (p<0.0001). One-year event rates were low including a TLF rate of 12.8% and an ST rate of 0.6% at 12 months. CONCLUSIONS One-year outcomes of OMEGA show low rates of TLF, revascularization and ST. This supports safety and efficacy of the OMEGA BMS for the treatment of coronary artery disease.
-
3.
No need for immediate freezing of metal ion blood samples in patients with metal-on-metal hip articulations.
Lindberg-Larsen, M, Penny, JØ
Danish medical journal. 2012;(12):A4546
Abstract
INTRODUCTION A recent British medical device alert suggested monitoring patients with metal-on-metal (MoM) articulations using blood metal ions. These blood samples are usually frozen immediately and shipped frozen for analysis. Simply posting the samples in the mail would lower the costs and simplify logistics of metal ion testing. The aim of this study was to determine whether the metal ion value in the blood is stable when kept at room temperature. MATERIAL AND METHODS Eight patients with large-diameter MoM articulations were included. We compared levels of chromium (Cr) and cobalt (Co) in whole-blood samples frozen immediately, after four days and after 30 days. RESULTS We found Co ranging from 0.64 to 10.9 µg/l and Cr from 0.76 to 5.16 µg/l. There was no systematic reduction in the mean level of Cr and Co of the eight patients when we compared results from the blood frozen immediately with the blood frozen after four days and after thirty days. There was a tendency towards greater variation (limits of agreement) in the results of the individual blood samples over thirty days, but these increases were non-significant. CONCLUSION The variation of Co and Cr ions in blood kept at room temperature for up to thirty days is within clinically acceptable levels for the diagnosis of excess wear.
-
4.
Toxic metals and the menopause.
Vahter, M, Berglund, M, Akesson, A
The journal of the British Menopause Society. 2004;(2):60-4
Abstract
Toxicity of chemicals and environmental pollutants may be expressed differently in women than in men. Until recently, most research involved men. With the initiation of studies on the effects of environmental pollutants in women, there is increasing evidence of effects at specific periods in a woman's life; however, accrual of data is slow. This review focuses on the kinetics and effects of the toxic metals lead and cadmium related to menopause. Data on other metals are extremely limited. One of the few well described examples of menopausal-related effects of metals is the very painful disease called Itai-itai, which is a combination of osteoporosis, osteomalacia and renal damage caused by consumption of cadmium-polluted rice. Recent data demonstrate mild effects of cadmium on both kidney and bone with present environmental exposure levels. Women may be at greater risk than men, because of increased gastrointestinal uptake of cadmium at low iron stores, which is common in women of childbearing age. Thus, improvement of iron status, which often occurs at menopause, has a positive effect on cadmium exposure in the sense that its absorption decreases. Cadmium accumulates in the kidney with a half-life of 10-30 years. The health effects appear around menopause, concurrent with the peak in renal cadmium concentrations. About 90% of body lead is localised to bone. There is a significant release of bone lead after the menopause, in association with the acceleration of bone resorption. Thus, postmenopausal women may be at increased risk of adverse effects of lead.
-
5.
Metalloid tolerance based on phytochelatins is not functionally equivalent to the arsenite transporter Acr3p.
Wysocki, R, Clemens, S, Augustyniak, D, Golik, P, Maciaszczyk, E, Tamás, MJ, Dziadkowiec, D
Biochemical and biophysical research communications. 2003;(2):293-300
Abstract
Active transport of metalloids by Acr3p and Ycf1p in Saccharomyces cerevisiae and chelation by phytochelatins in Schizosaccharomyces pombe, nematodes, and plants represent distinct strategies of metalloid detoxification. In this report, we present results of functional comparison of both resistance mechanisms. The S. pombe and wheat phytochelatin synthase (PCS) genes, when expressed in S. cerevisiae, mediate only modest resistance to arsenite and thus cannot functionally compensate for Acr3p. On the other hand, we show for the first time that phytochelatins also contribute to antimony tolerance as PCS fully complement antimonite sensitivity of ycf1Delta mutant. Remarkably, heterologous expression of PCS sensitizes S. cerevisiae to arsenate, while ACR3 confers much higher arsenic resistance in pcsDelta than in wild-type S. pombe. The analysis of PCS and ACR3 homologues distribution in various organisms and our experimental data suggest that separation of ACR3 and PCS genes may lead to the optimal tolerance status of the cell.
-
6.
Reduction kinetics of Fe(III), Co(III), U(VI), Cr(VI), and Tc(VII) in cultures of dissimilatory metal-reducing bacteria.
Liu, C, Gorby, YA, Zachara, JM, Fredrickson, JK, Brown, CF
Biotechnology and bioengineering. 2002;(6):637-49
Abstract
The reduction kinetics of Fe(III)citrate, Fe(III)NTA, Co(III)EDTA-, U(VI)O(2) (2+), Cr(VI)O(4) (2-), and Tc(VII)O(4) (-) were studied in cultures of dissimilatory metal reducing bacteria (DMRB): Shewanella alga strain BrY, Shewanella putrefaciens strain CN32, Shewanella oneidensis strain MR-1, and Geobacter metallireducens strain GS-15. Reduction rates were metal specific with the following rate trend: Fe(III)citrate > or = Fe(III)NTA > Co(III)EDTA- >> UO(2)(2+) > CrO(4)(2-) > TcO(4)(-), except for CrO(4) (2-) when H(2) was used as electron donor. The metal reduction rates were also electron donor dependent with faster rates observed for H(2) than lactate- for all Shewanella species despite higher initial lactate (10 mM) than H2 (0.48 mM). The bioreduction of CrO(4) (2-) was anomalously slower compared to the other metals with H(2) as an electron donor relative to lactate and reduction ceased before all the CrO(4)(2-) had been reduced. Transmission electron microscopic (TEM) and energy-dispersive spectroscopic (EDS) analyses performed on selected solids at experiment termination found precipitates of reduced U and Tc in association with the outer cell membrane and in the periplasm of the bacteria. The kinetic rates of metal reduction were correlated with the precipitation of reduced metal phases and their causal relationship discussed. The experimental rate data were well described by a Monod kinetic expression with respect to the electron acceptor for all metals except CrO(4)(2-), for which the Monod model had to be modified to account for incomplete reduction. However, the Monod models became statistically over-parameterized, resulting in large uncertainties of their parameters. A first-order approximation to the Monod model also effectively described the experimental results, but the rate coefficients exhibited far less uncertainty. The more precise rate coefficients of the first-order model provided a better means than the Monod parameters, to quantitatively compare the reduction rates between metals, electron donors, and DMRB species.