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PubMed1996

Speciation of chromium by coupled column HPLC-ICP-MS - the effects of interfering ions.

ICP-MS is used as an element selective detector for chromium species in aquatic samples using a coupled columm system consisting of a cation guard column and an anion column. The effects of large concentrations of disturbing ions, like NO(3)(-), Cl(-), CO(3)(2-) and SO(4)(2-), are discussed and the comparison with the use of different chromium isotopes for data acquisition is given. Quite low concentrations such as 100 mg/l of CO(3)(2-), 10 mg/l Cl(-) and even 5 mg/l SO(4)(2-) can cause an overestimation of chromium if not properly resolved1995 / Accepted: 24 October 1995

Journal Article↗
PubMed2006

D and 18O enrichment measurements in biological fluids in a continuous-flow elemental analyser with an isotope-ratio mass spectrometer using two configurations.

In doubly labelled water studies, biological sample enrichments are mainly measured using off-line techniques (equilibration followed by dual-inlet introduction) or high-temperature elemental analysis (HT-EA), coupled with an isotope-ratio mass spectrometer (IRMS). Here another continuous-flow method, (CF-EA/IRMS), initially dedicated to water, is tested for plasma and urine analyses. The elemental analyser configuration is adapted for each stable isotope: chromium tube for deuterium reduction and glassy carbon reactor for 18O pyrolysis. Before on-line conversion of water into gas, each matrix is submitted to a short and easy treatment, which is the same for the analysis of the two isotopes. Plasma is passed through centrifugal filters. Urine is cleaned with black carbon and filtered (0.45 microm diameter). Tested between 150 and 300 ppm in these fluids, the D/H ratio response is linear with good repeatability (SD<0.2 ppm) and reproducibility (SD<0.5 ppm). For 18O/16O ratios (from 2000 to 2200 ppm), the same repeatability is obtained with a between-day precision lower than 1.4 ppm. The accuracy on biological samples is validated by comparison to classical dual-inlet methods: 18O analyses give more accurate results. The data show that enriched physiological fluids can be successfully analysed in CF-EA/IRMS.

Animals↗
PubMed1976

The use of technetium-99m labelled heat-damaged red cells for the quantitative measurement of splenic function.

A comparison of the rates of clearance of 51Cr labelled and 99mTc labelled heat-damaged red cells in 25 patients and 4 control subjects is reported. Very little correlation was found between the clearance half-times of the two types of labelled cells when the cells were labelled with 99mTc prior to heat damaging. The correlation was improved when the labelling step occurred after the cells had been damaged. Urinary excretion measurements revealed that the rate of excretion of 99mTc could be as much as nine times that of the 51Cr label. 99mTc labelled heat-damaged red cells were found not to be sufficiently stable a preparation for use in quantitative clearance studies.

Chromium Isotopes↗
PubMed1988

Effects of endotoxemia on systemic plasma loss and hematocrit in rats.

Endotoxemia in rats increases plasma extravasation but does not result in continuously rising hematocrit. These contradictory observations led us to design a study in anesthetized rats (C, control rats, n = 10; E, endotoxin rats, n = 10) in which we continuously measured in blood hematocrit (conductivity cell) and changes in concentration of 125I-HSA (human serum albumin) and 51Cr-labeled red cell (51Cr-RBC; multichannel analyzer) in an extracorporeal circuit. In two additional series of experiments we measured in blood samples changes in protein concentration (series II, C: n = 7, E: n = 7) and uptake of intraperitoneally injected 125I-HSA and 51Cr-RBC (reflecting lymph flow rate; series III, C: n = 6, E: n = 7). Endotoxemia was induced by infusion (iv, 0.2 ml/100 g.hr) of Escherichia coli endotoxin (20 mg/kg) from t = 0 to t = 60 min; controls received saline. Experiments ended at t = 120 (series I and II) or 150 min (series III). The endotoxemia resulted in a marked rise of serum lactate (by ca 500% at t = 120); heart rate increased and central venous pressure decreased (by ca 20 and -95% at t = 120, respectively). All rats showed characteristic changes in hematocrit during endotoxemia: an increase from t = 20 to t = 45 (by ca 9%) followed by a decrease to preshock values or less at t = 120. The 51Cr activity per microliter blood cells did not change, indicating that there was no red cell mobilization. Protein concentration and 125I-HSA activity also showed a temporary increase during endotoxemia, but 125I-HSA activity per gram protein was decreased. Peritoneal uptake of 125I-HSA and 51Cr-RBC was significantly increased during endotoxemia (by 200%). We conclude that fluid extravasation during endotoxemia is temporary, mainly concerns plasma water, and is compensated by mechanisms like reabsorption and increased lymph flow, resulting in restoration of plasma volume.

Animals↗
PubMed1995

Chromium speciation by anion-exchange high-performance liquid chromatography with both inductively coupled plasma atomic emission spectroscopic and inductively coupled plasma mass spectrometric detection.

Development of a new method for the determination of Cr(III) and Cr(VI) is described. Anion-exchange high-performance liquid chromatography (HPLC) was used to separate Cr(III) and Cr(VI) with on-line detection by inductively coupled plasma atomic emission spectroscopy (ICP-AES) at 2766 A in preliminary studies, and inductively coupled plasma mass spectrometry (ICP-MS) with single-ion monitoring at m/z 52 and m/z 53 for final work. A mobile phase consisting of ammonium sulfate and ammonium hydroxide was used, and a simple chelation procedure with EDTA was followed to stabilize the Cr(III) species in standard solutions. ICP-MS results indicated the feasibility of using chromium isotope m/z 53 instead of the more abundant m/z 52 isotope due to a high mobile-phase background most significantly from the SO+ polyatomic interference. The absolute detection limits based on peak-height calculations were 40 pg for Cr(III) and 100 pg for Cr(VI) in aqueous media by HPLC-ICP-MS. The linear dynamic range extended from 5 ppb (ng/ml) to 1 ppm (micrograms/ml) for both species. By HPLC-ICP-AES, detection limits were 100 ng for Cr(III) and 200 ng for Cr(VI). Cr(III) was detected in NIST-SRM 1643c (National Institute of Standards and Technology-Standard Reference Material, Trace Elements in Water) by HPLC-ICP-MS at the 20 ppb level.

Chromatography, High Pressure Liquid↗
PubMed2001

Significance of serum soluble Fas ligand in patients with bladder carcinoma.

BACKGROUND: The interaction of Fas and Fas ligand (FasL) plays an important role in cytotoxic T-lymphocyte-mediated and natural killer cell-mediated apoptosis against tumor cells. Circulating soluble FasL (sFasL) has been suggested to provide protection from Fas-mediated apoptosis. The current study examined this possibility in patients with bladder carcinoma. METHODS: The levels of sFasL in the serum of 163 patients with bladder carcinoma were determined using an enzyme-linked immunoadsorbent assay. Antiautologous tumor cytotoxic activity was assessed by the 12-hour chromium isotope ((51)Cr) release assay. RESULTS: The mean serum level of sFasL in patients with bladder carcinoma was 2.5-fold higher than that in healthy donors. The level of serum sFasL in patients with muscle-invasive bladder carcinoma was 2.5-fold higher than that in patients with superficial bladder carcinoma. In addition, serum sFasL levels in patients with T1 and Tis bladder carcinoma was 2-fold and 2.7-fold higher, respectively, than levels in patients with Ta bladder carcinoma. The serum level of patients with sFasL in Grade 3 bladder carcinoma were 2.4-fold and 1.7-fold higher than that in patients with Grade 1 and Grade 2 bladder carcinoma, respectively. Patients with Ta bladder carcinoma with a low level of serum sFasL (less than the median value) had a longer postoperative tumor-free interval than patients with a high sFasL level (greater than the median value) in the 5-year follow-up. There was an apparent inverse correlation between the level of serum sFasL and antiautologous tumor cytotoxic activity. CONCLUSIONS: The results of the current study demonstrated that the level of serum sFasL is correlated with both disease progression and increase in the tumor grade, and that an elevated serum sFasL level predicted early recurrence in patients with Ta bladder carcinoma. These findings suggest that elevated serum sFasL levels might be associated with a greater risk of disease progression and recurrence in patients with bladder carcinoma.

Adult↗
PubMed1969

Serum albumin.

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Albumins↗