Quantitative susceptibility mapping (QSM) is a novel technique which allows determining the bulk magnetic susceptibility distribution of tissue in vivo from gradient echo magnetic resonance phase images. It is commonly assumed that paramagnetic iron is the predominant source of susceptibility variations in gray matter as many studies have reported a reasonable correlation of magnetic susceptibility with brain iron concentrations in vivo. Instead of performing direct comparisons, however, all these studies used the putative iron concentrations reported in the hallmark study by Hallgren and Sourander (1958) for their analysis. Consequently, the extent to which QSM can serve to reliably assess brain iron levels is not yet fully clear. To provide such information we investigated the relation between bulk tissue magnetic susceptibility and brain iron concentration in unfixed (in situ) post mortem brains of 13 subjects using MRI and inductively coupled plasma mass spectrometry. A strong linear correlation between chemically determined iron concentration and bulk magnetic susceptibility was found in gray matter structures (r=0.84, p<0.001), whereas the correlation coefficient was much lower in white matter (r=0.27, p<0.001). The slope of the overall linear correlation was consistent with theoretical considerations of the magnetism of ferritin supporting that most of the iron in the brain is bound to ferritin proteins. In conclusion, iron is the dominant source of magnetic susceptibility in deep gray matter and can be assessed with QSM. In white matter regions the estimation of iron concentrations by QSM is less accurate and more complex because the counteracting contribution from diamagnetic myelinated neuronal fibers confounds the interpretation.

The results of this study show that transverse MR relaxation rates are valid in vivo measures of brain iron concentration, with R2* as the preferred parameter because it is more sensitive than R2 to variations in iron concentration and can depict differences in white matter. PurposeTo investigate the relationship between transverse relaxation rates R2 and R2*, the most frequently used surrogate markers for iron in brain tissue, and chemically determined iron concentrations.Materials and MethodsThis study was approved by the local ethics committee, and informed consent was obtained from each individual’s next of kin. Quantitative magnetic resonance (MR) imaging was performed at 3.0 T in seven human postmortem brains in situ (age range at death, 38–81 years). Following brain extraction, iron concentrations were determined with inductively coupled plasma mass spectrometry in prespecified gray and white matter regions and correlated with R2 and R2* by using linear regression analysis. Hemispheric differences were tested with paired t tests.ResultsThe highest iron concentrations were found in the globus pallidus (mean ± standard deviation, 205 mg/kg wet mass ± 32), followed by the putamen (mean, 153 mg/kg wet mass ± 29), caudate nucleus (mean, 92 mg/kg wet mass ± 15), thalamus (me...

Background: Cadmium is a widespread toxic metal with potential cardiovascular effects, but no studies have evaluated cadmium and incident cardiovascular disease. We evaluated the association of urine cadmium concentration with cardiovascular disease incidence and mortality in a large population-based cohort. Methods: We conducted a prospective cohort study of 3348 American Indian adults 45–74 years of age from Arizona, Oklahoma, and North and South Dakota, who participated in the Strong Heart Study in 1989–1991. Urine cadmium was measured using inductively coupled plasma mass spectrometry. Follow-up extended through 31 December 2008. Results: The geometric mean cadmium level in the study population was 0.94 μg/g (95% confidence interval [CI] = 0.92–0.96). We identified 1084 cardiovascular events, including 400 deaths. After adjustment for sociodemographic and cardiovascular risk factors, the hazard ratios (HRs) (comparing the 80th to the 20th percentile of urine cadmium concentrations) was 1.43 for cardiovascular mortality (95% CI = 1.21–1.70) and 1.34 for coronary heart disease mortality (1.10–1.63). The corresponding HRs for incident cardiovascular disease, coronary heart disease, stroke, and heart failure were 1.24 (1.11–1.38), 1.22 (1.08–1.38), 1.75 (1.17–2.59), and 1.39 (1.01–1.94), respectively. The associations were similar in most study subgroups, including never-smokers. Conclusions: Urine cadmium, a biomarker of long-term exposure, was associated with increased cardiovascular mortality and increased incidence of cardiovascular disease. These findings support that cadmium exposure is a cardiovascular risk factor.

Vibrio cholerae and enterotoxic Escherichia coli (ETEC) remain two dominant bacterial causes of severe secretory diarrhea and still a significant cause of death, especially in developing countries. In order to investigate new effective and inexpensive therapeutic approaches, we analyzed nanoparticles synthesized by a green approach using corresponding salt (silver or zinc nitrate) with aqueous extract of Caltropis procera fruit or leaves. We characterized the quantity and quality of nanoparticles by UV-visible wavelength scans and nanoparticle tracking analysis. Nanoparticles could be synthesized in reproducible yields of approximately 10(8) particles/ml with mode particles sizes of approx. 90-100 nm. Antibacterial activity against two pathogens was assessed by minimal inhibitory concentration assays and survival curves. Both pathogens exhibited similar resistance profiles with minimal inhibitory concentrations ranging between 5×10(5) and 10(7) particles/ml. Interestingly, zinc nanoparticles showed a slightly higher efficacy, but sublethal concentrations caused adverse effects and resulted in increased biofilm formation of V. cholerae. Using the expression levels of the outer membrane porin OmpT as an indicator for cAMP levels, our results suggest that zinc nanoparticles inhibit adenylyl cyclase activity. This consequently deceases the levels of this second messenger, which is a known inhibitor of biofilm formation. Finally, we demonstrated that a single oral administration of silver nanoparticles to infant mice colonized with V. cholerae or ETEC significantly reduces the colonization rates of the pathogens by 75- or 100-fold, respectively.

Electronic cigarettes (e-cigarettes) generate an aerosol by heating a solution (e-liquid) with a metallic coil. Whether metals are transferred from the coil to the aerosol is unknown. Our goal was to investigate the transfer of metals from the heating coil to the e-liquid in the e-cigarette tank and the generated aerosol. We sampled 56 e-cigarette devices from daily e-cigarette users and obtained samples from the refilling dispenser, aerosol, and remaining e-liquid in the tank. Aerosol liquid was collected via deposition of aerosol droplets in a series of conical pipette tips. Metals were reported as mass fractions (μg/kg) in liquids and converted to mass concentrations (mg/m³) for aerosols. Median metal concentrations (μg/kg) were higher in samples from the aerosol and tank vs. the dispenser (all p<0.001): 16.3 and 31.2 vs. 10.9 for Al; 8.38 and 55.4 vs. <0.5 for Cr; 68.4 and 233 vs. 2.03 for Ni; 14.8 and 40.2 vs. 0.476 for Pb; and 515 and 426 vs. 13.1 for Zn. Mn, Fe, Cu, Sb, and Sn were detectable in most samples. Cd was detected in 0.0, 30.4, and 55.1% of the dispenser, aerosol, and tank samples respectively. Arsenic was detected in 10.7% of dispenser samples (median 26.7μg/kg) and these concentrations were similar in aerosol and tank samples. Aerosol mass concentrations (mg/m³) for the detected metals spanned several orders of magnitude and exceeded current health-based limits in close to 50% or more of the samples for Cr, Mn, Ni, and Pb. Our findings indicate that e-cigarettes are a potential source of exposure to toxic metals (Cr, Ni, and Pb), and to metals that are toxic when inhaled (Mn and Zn). Markedly higher concentrations in the aerosol and tank samples versus the dispenser demonstrate that coil contact induced e-liquid contamination. https://doi.org/10.1289/EHP2175.

Treatment of acute burn wounds with silver sulfadiazine (SSD) has raised concern about potential silver toxicity. Numerous adverse reactions and side effects have been reported and an increasing resistance to SSD, especially in Pseudomonas strains, have motivated researchers to search for an alternative wound dressing. Recently, a silver-coated wound dressing Acticoat (Smith & Nephew, Inc.) has become available for use in burn patients. It is a three-ply dressing, consisting of an inner rayon/polyester absorptive core between two layers of silver-coated, high-density polyethylene mesh. In a moist environment, the nanocrystals of silver are released and improve the microbial control in the wound. After 1 week of local treatment with Acticoat in a young, previously healthy 17-year-old boy with 30% mixed depth burns, hepatotoxicity and argyria-like symptoms, a grayish discoloration of the patient's face, appeared. The silver levels in plasma (107 μg/kg) and urine (28 μg/kg) were clearly elevated, as well as the liver enzymes. As soon as the local application of Acticoat was aborted, the clinical symptoms and liver enzymes returned to the normal values. This is the first report on silver toxicity in a patient with 30% burns who received Acticoat for local treatment. Due to substantial experiences with adverse SSD reactions and side effects, it is appropriate to keep the possibility of a toxic silver effect in burn patients treated with Acticoat silver-coated wound dressing in mind. The silver levels in plasma and/or urine should be monitored.