Evidence Of Cr Research Articles

Real-world time-to-castration resistance (CR) among patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) initiating apalutamide (APA), enzalutamide (ENZ), or abiraterone acetate (ABI) from an oncology database.

65 Background: CR is an important clinical indicator of disease progression and worsening overall survival among pts with mCSPC. This study describes real-world time-to-CR progression in an oncology setting among pts with mCSPC who initiated APA, ENZ, or ABI in the United States. Methods: Clinical data from the Flatiron Metastatic Prostate Cancer (PC) Core Registry Electronic DataMart (1/1/2013 – 07/31/2022) were evaluated. Metastatic pts without evidence of CR before initiating a next-generation androgen inhibitor (AAI) were classified into exclusive treatment cohorts based on the start date (index date) for APA, ENZ, or ABI. CR was identified by a Flatiron algorithm searching for: 1) mention of CR in patient charts, 2) rising prostate-specific antigen (PSA) levels documented from laboratory testing, or 3) mention of rising PSA while on hormonal therapy from unstructured data sources. Pts had ≥12 months (mo) of clinical data pre-index date and were followed from the index date until the end of clinical activity (including death) or data availability. The proportion of pts developing CR was described separately for each cohort using Kaplan-Meier analysis up to 24 mo post-index, with no adjustment for baseline confounders. CR progression rates in the current analysis were descriptively compared to those observed in Phase 3 trials where available. Results: A total of 155 APA, 385 ENZ and 711 ABI pts were evaluated. Mean age at index was ~73 years in each group. Mean follow-up was 12.8 mo (APA), 13.4 mo (ENZ) and 20.6 mo (ABI). Use of androgen deprivation therapy prior to initiation of AAI was observed in ~85% of pts. The median time between documented metastasis and the index date was 2.3 mo (APA), 2.8 mo (ENZ), and 2.3 mo (ABI). Progression rates to CR are shown. By 24 mo, the median time-to-CR was not reached with any treatment studied. By 24 mo, progression to CR was observed in 26% of APA pts in this analysis (32% in TITAN); 36% of ENZ pts in this analysis (25% in ARCHES); and 33% of ABI pts in this analysis (progression to CR not reported in LATITUDE). Conclusions: In this real-world database, the observed proportions of pts progressing to CRPC for the APA and ENZ cohorts were generally consistent with results of Phase 3 trials and include a small proportion of pts with early progression to CRPC. Increased physician awareness of the benefits of early initiation of an AAI along with identification of baseline biomarkers associated with early progression to CRPC may improve clinical outcomes. [Table: see text]

Bioavailability of chromium, nickel, iron and manganese in relation to their speciation in coastal sediments downstream of ultramafic catchments: A case study in New Caledonia.

Coastal sediments downstream of ultramafic catchments can show Ni and Cr concentration well above sediment quality guidelines. Despite their potential ecological impact, the bioavailability of these trace metals in such sedimentary settings has been poorly investigated. In this study, we tried to fill this gap by performing kinetic EDTA-extractions across a shore-to-reef gradient in lagoon sediments downstream of an ultramafic catchment in New Caledonia and interpreting the results in regard of synchrotron-derived speciation. Measured bioavailability ranged from very low for Cr (below 1% of total Cr) to medium for Ni (below 5% of total Ni). Both trace metals showed a decreasing shore-to-reef bioavailability gradient reflecting the larger deposition of ultramafic sediments close to the shore. According to synchrotron-derived speciation data, the very low bioavailability of Cr is attributed to its major occurrence as Cr(III)-bearing Fe-(oxyhydr)oxides and phyllosilicates, with no evidence of Cr(VI). Considering the low occurrence of Fe-sulfides, the medium bioavailability of Ni is considered to arise mainly from the reductive dissolution of Ni-bearing Fe-(oxyhydr)oxides during early diagenesis. This reaction also explains the medium bioavailability of Fe (up to 15% of total Fe) and the positive correlation observed with Total Organic Carbon (TOC). In this regard, this latter parameter appears as a major driver of Ni and Fe bioavailability in coastal sediments downstream of ultramafic catchments. On the opposite, in the absence of Mn-oxides, TOC has no influence on Mn bioavailability (up to 30% of total Mn) that appears more likely driven by sediment sources. From an ecological point of view, considering the Australian and New-Zealand High Interim Sediment Quality Guidelines (ANZ-ISQG-H), Cr should not represent a significant risk towards benthic communities in coastal sediments downstream of ultramafic catchments. On the opposite, Ni, Fe and Mn might represent an ecological risk that should be further investigated in such sedimentary settings.

Isotope fractionation and spectroscopic analysis as an evidence of Cr(VI) reduction during biosorption

This work investigates the mechanisms behind Cr(VI) biosorption/reduction on three biomaterials (brewers draff, grape waste and synthetic humic acid). Coupled Cr isotope analysis with ICP-OES, XPS and SEM was tested as a novel approach to study the reduction of Cr(VI) by the biomaterials. The Cr(VI) biosorption process was accompanied with heavier Cr isotopes enrichment in the remaining Cr(VI) fraction. A significant fractionation of Cr stable isotopes was observed with no significant pH effect; δ53Cr of the remaining fraction ranged from 0.2‰ to 1.9‰ while δ53Cr of the product (sorbed Cr) ranged from −1.2‰ to −2.8‰. The Rayleigh fractionation model fitted well the measured data and Cr isotope analysis provides thus an efficient tool to quantify Cr(VI) reduction by different biomaterials. In general, the sorption/reduction potential of the three studied biomaterials decreased in the following order: grape waste>humic acids>brewers draff.

1 Exposure to CCA treated wood amongst food caterers and residents in informal areas of Cape Town

ObjectivesThe study investigated if wood usage by street food caterers and household residents from informal settlements in Cape Town resulted in the absorption of Cr, Cu and As due to...

The chemical form of metallic debris in tissues surrounding metal-on-metal hips with unexplained failure

Implant-derived material from metal-on-metal (MOM) hip arthroplasties may be responsible for an unexplained tissue inflammatory response. The chemical form of the metal species in the tissues is predominantly chromium (Cr), but the currently used techniques have not been able to determine whether this is Cr(III) phosphate or Cr(III) oxide. The analytical challenge must overcome the fact that the metal in the tissues is at a relatively low concentration and tissue preparation or the microscopy beam used can affect the results. Microfocus X-ray spectroscopy using a synchrotron beam is useful in addressing both these issues. Using this technique we compared tissue from failed MOM hips with: (1) tissue from metal-on-polyethylene (MOP) hips; (2) chemical standards; (3) metal discs cut from MOM hips. The most abundant implant-related species in all MOM hip tissues contained Cr. Comparison with standards revealed the chemical form was Cr(III) phosphate, which did not vary with manufacturer type (four types analysed) or level of blood metal ions. Cobalt (Co) and molybdenum (Mo) were occasionally present in areas of high Cr. Co was normally found in a metallic state in the tissue, while Mo was found in an oxidized state. The variety of metallic species may have arisen from corrosion, wear or a combination of both. No evidence of Cr(VI) was seen in the tissues examined.

Chromium speciation in oxide-type compounds: application to minerals, gems, aqueous solutions and silicate glasses

Cr K-edge XANES spectra were obtained for a variety of Cr-bearing model compounds containing Cr(II), Cr(III), Cr(IV), Cr(V) and Cr(VI), in which the Cr-site symmetry is D4h, Oh and Td. The centroid position of the pre-edge feature is a better indicator of the Cr valence than the edge position. In Cr-rich oxides, higher-energy transitions must be excluded in order to refine a robust valence for Cr. The pre-edge for chromates is not unique and varies as a function of the CrO4 2− moiety distortion, which is often related to Cr-polymerization (monochromate vs. dichromate). Both the analogy with the Mn K-pre-edge information and ab initio FEFF calculations of the pre-edge feature for Cr(III) and Cr(VI) confirm the experimental trends. This methodology is applied to the Cr K-edge pre-edge feature collected in gems (emerald, spinel and ruby), the layered minerals fuchsite and kammererite, two Cr-bearing aqueous solutions and a set of sodo-calcic silicate glasses used for bottling sparkling white wine. In emerald and fuchsite, the Cr-site is differently distorted than its ruby or spinel counterpart. In a Cr(III)-bearing aqueous solution and sodo-calcic glass, no evidence for Cr(III) with Td and C3v symmetry is detected. However, minor amounts of chromate moieties (most likely monomeric) are detected in a glass synthesized in air. Preliminary spectra for the wine bottle glass suggest that only trace amounts of chromates might possibly be present in these glasses.

Column study of chromium(VI) adsorption from electroplating industry by coconut coir pith

The removal of Cr(VI) from electroplating wastewater by coir pith was investigated in a fixed-bed column. The experiments were conducted to study the effect of important parameters such as bed depth (40–60 cm) and flow rate (10–30 ml min −1). At 0.05 C t / C 0, the breakthrough volume increased as flow rate decreased or a bed depth increased due to an increase in empty bed contact time (EBCT). The bed depth service time model (BDST) fit well with the experimental data in the initial region of the breakthrough curve, while the simulation of the whole curve using non-linear regression analysis was effective using the Thomas model. The adsorption capacity estimated from the BDST model was reduced with increasing flow rate, which was 16.40 mg cm −3 or 137.91 mg Cr(VI) g −1 coir pith for the flow rates of 10 ml min −1 and 14.05 mg cm −3 or 118.20 mg Cr(VI) g −1 coir pith for the flow rates of 30 ml min −1. At the highest bed depth (60 cm) and the lowest flow rate (10 ml min −1), the maximum adsorption reached 201.47 mg Cr(VI) g −1 adsorbent according to the Thomas model. The column was regenerated by eluting chromium using 2 M HNO 3 after adsorption studies. The desorption of Cr(III) in each of three cycles was about 67–70%. The desorption of Cr(III) in each cycle did not reach 100% due to the fact that Cr(V) was present through the reduction of Cr(VI), and was still in coir pith, possibly bound to glucose in the cellulose part of coir pith. Therefore, the Cr(V) complex cannot be desorbed in solution. The evidence of Cr(V) signal was observed in coir pith, α-cellulose and holocellulose extracted from coir pith using electron spin resonance (ESR).

Evidence of Cr(VI) formation during analysis of leatherProposal of an alternative method of analysis through the ion-chromatographic approach and post-column reaction

Evidence of Cr(VI) formation during analysis of leatherProposal of an alternative method of analysis through the ion-chromatographic approach and post-column reaction

Evidence of Cr(VI) formation during analysis of leather: Proposal of an alternative method of analysis through the ion-chromatographic approach and post-column reaction

The formation of Cr(VI) in Cr(III) tanned leather, in neutral and alkaline solution, has been demonstrated by means of crossed experiments using different pH buffers, ethylenediaminetetraacetic acid as Cr(III) complexing agent and NaCl solutions. According to the found results the composition of the extracting solution suitable to extract Cr(VI) amount present in leather was pH 4.4 (which is also the tanned leather natural pH) and 5% NaCl (w/v). Interferences coming from coloured compounds have been eliminated with suitable SPE cartridges. A new protocol for the analysis of Cr(VI) based on ion chromatography and a diphenylcarbazide post-column reaction has been implemented. The use of a large volume injection loop (500μl) allowed to obtain a very low quantification limit (0.15mgkg−1) despite the low amount of leather extracted (0.2g with respect to 2.0g used by the IUC 18 official method). Evidence of the transient nature of Cr(VI) in leather requires using the external calibration procedure for the correct quantification of the species.

Evidence of Cr+4 doping in Sr3Ti2O7 from structural, optical and magnetic properties

Evidence of Cr+4 doping in Sr3Ti2O7 from structural, optical and magnetic properties

Formation, Properties, and Characterization of a Fully Reduced Fe(II)Fe(II) Form of Spinach (and Parsley) [2Fe-2S] Ferredoxin with the Macrocyclic Complex [Cr(15-aneN(4))(H(2)O)(2)](2+) as Reductant.

Reduction of spinach and parsley ferredoxin FdI in the Fe(III)Fe(III) state with the 1,4,8,12-tetraazacyclopentadecane complex [Cr(15-aneN(4))(H(2)O)(2)](2+), here written as Cr(II)L, provides the first evidence for two 1-equiv steps yielding an Fe(II)Fe(II) product. Rate constants (25 degrees C) for spinach FdI are 2760 and 660 M(-)(1) s(-)(1), respectively, at pH 7.5, I = 0.100 M (NaCl). An important observation is that the Cr(III)L generated in the first step remains attached to the Fe(II)Fe(III) product and perturbs the protein active site sufficiently to make the second stage possible. The second Cr(II)L reduction is of the "outer-sphere" type, and the Cr(III)L generated is not attached to the protein. Anaerobic reoxidation of the fully reduced protein with [Co(NH(3))(6)](3+) is rapid and can be achieved with approximately 80% recovery of the Fe(III)Fe(III) oxidation state over 40 min. Air oxidation yields the Cr(III)L product Fe(III)Fe(III).Cr(III)L (Fe:Cr = 2:1). With Anabaena variabilis only a one-step reduction is observed and there is no Cr(III)L attachment. From a comparison of amino acid sequences with spinach (and parsley) FdI, a likely point of Cr(III)L attachment is indicated. Comparisons are made with dithionite as reductant. In addition, square-wave voltammetry on spinach Fe(III)Fe(III).Cr(III)L gives two reduction potentials -273 and -410 mV vs NHE. The different redox products have been characterized by EPR. Using (1)H NMR line-broadening techniques, evidence for Cr(III)L binding at a surface site close to Tyr-25/Tyr-82 is obtained. Also from investigations with redox-inactive [Cr(en)(3)](3+) as a competitive inhibitor for Cr(II)L reduction of spinach Fe(III)Fe(III), Tyr-25/Tyr-82 is proposed as the site for Cr(II)L reduction. From an extension of studies to include reduction of Fe(III)Fe(III).Cr(III)L with Cr(II)L, evidence is obtained for a second reaction site when that at Tyr-25/Tyr-82 is no longer available.

Observations of the (1,0) vibrational band of interstellar CN toward Zeta Ophiuchi

Very high SNR, high-resolution observations of the 3580 A spectral region toward Zeta Oph have been obtained in an effort to detect the weak R(0) line corresponding to the (1,0) vibrational band of interstellar CN. The measurement of 0.67 + or - 0.06 mA for the CN (1,0) R(0) line strength indicates a J = 0 column density which is consistent with earlier determinations from the much stronger (0,0) R(0) line and the assumption of a single-component line profile. This finding implies that the complex velocity structure evident from CO radio observations of the Zeta Oph line of sight does not seriously complicate the saturation corrections for the CN lines. The Zeta Oph observations also reveal an equivalent width of 2.14 + or - 0.08 mA for the (3,0) R(0) line of interstellar (C-12)H(+) at 3579.02 A along with strong evidence of Cr I 3578.69 absorption. 44 refs.

Slag Metal Reactions during Submerged Arc Welding of Alloy Steels

The transfer of Cr, Si, Mn, P, S, C, Ni, and Mo between the slag and the weld pool has been studied for submerged arc welds made with calcium silicate and manganese silicate fluxes. The results show a strong interaction between Cr and Si transfer but no interaction with Mn. The manganese silicate flux produces lower residual sulfur while the calcium silicate fluxes are more effective for removal of phosphorus. The effective oxygen reaction temperature lies between 1700 and 2000 °C for all elements studied. Evidence of Cr and Mn loss by metal vaporization is also presented.

Evidence for Cr 3+ in four-coordination: ESR- and optical investigations of Cr-doped AlPO 4-crystals

In AlPO 4 crystals, doped with chromium, 99.7 per cent of the Cr 3+ ions occupy six-coordinated sites in the channels along the c-axis. They give rise to optical absorption in the visible region. On the other hand, the observed ESR spectrum can be ascribed to a small fraction (0.3 per cent) of the Cr 3+ ions which are trapped on substitutional tetrahedral sites. At X-band only one fine structure component is observed, the effective g-factors (in the S′ = 1 2 formalism) being: g ξ ́ = 2.550±0.005, g η ́ = 1.710 ±0.010 and g ζ ́ = 4.943 ±0.003 . The observed fine structure component can be attributed to the − 1 2 → + 1 2 transition in the S = 3 2 manifold using a spin-hamiltonian H=DS 2 z+E(S 2 x−S 2 y+g xβH xS x+ g zβH zS y+g zβH zS z , with E/ D = 0.233 and g z = 2.00, g x = 1.99, g y = 1.92.