Biomedical subjects

Z Karpas

Publications and source records attributed to Z Karpas.

10 recordsLinked to original sources

PubMed2005

Determination of 234U/238U ratio: comparison of multi-collector ICPMS and ICP-QMS for water, hair and nails samples, and comparison with alpha-spectrometry for water samples.

The (234)U/(238)U ratio in water, hair and nails samples was determined by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) and by alpha-spectrometry for the water samples only. A correlation of 0.99 was found between the two ICPMS methods and of 0.98 with alpha-spectrometry. The range of activity ratios was between 0.9 and 2.6 according to the MC-ICPMS measurements. The reproducibility of both ICPMS techniques was better than 4% for water samples containing 1 mug l(-1) of uranium and a (234)U/(238)U atom ratio of 54.9 x 10(-6). Sample preparation for the ICPMS consisted of dilution of water samples containing >10 microg l(-1) of uranium and measurement time was approximately 1 min, while alpha-spectrometry involved pre-concentration and separation of the uranium and counting times of 1,000 min.

Body Burden↗

PubMed2005

Urine, hair, and nails as indicators for ingestion of uranium in drinking water.

The concentration of uranium in urine, hair, and nails due to continuous exposure through ingestion of drinking water was studied. The study population consisted of 205 individuals living in 134 different households in southern Finland where drinking water is supplied from private drilled wells. The population was selected to include a broad range of uranium daily intake from drinking water (0.03-2,775 microg d). The uranium content in drinking water, urine (overnight collection), hair and nails was determined by ICPMS. Uranium in urine was corrected for the matrix effects by use of thallium as an internal standard and adjusted by creatinine normalization. Hair and toenail samples were rinsed to remove external contamination prior to acid digestion and analysis. The uranium content in all excretion pathways was correlated with the uranium intake, particularly at elevated levels (> or =10 microg d) where drinking water was the major source of exposure to uranium. The median of the individual uranium absorption factors for urine, hair, and toenails were fu=0.003, fh=0.003, and fn=4 x 10, respectively. The association between the different bioassays was examined. The absorption factor, f1, was calculated for the population with an intake above 10 microg d and was below 0.01 for 72% of the study persons (range 0.0002 to 0.070). No statistically significant difference in f1 values was found between women and men. However, the absorption factor was higher among younger (< 60 y) than older (> or =60 y) subjects and among people with a lower exposure (below 100 microg d) than among those that ingest over 100 microg d.

Administration, Oral↗

PubMed2005

Measurement of the 234U/238U ratio by MC-ICPMS in drinking water, hair, nails, and urine as an indicator of uranium exposure source.

The isotopic ratio (234)U/(238)U in drinking water and in hair, toenail, and urine samples from 45 individuals who consumed 0.2-2775 microg d(-1) of uranium in their drinking water was determined using a multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS). The U/U atom ratio in the water samples varied from 51 x 10(-6) to 252 x 10(-6) whereas in secular equilibrium (i.e., unity activity ratio) the ratio is 54.9 x 10(-6). The correlation of the (234)U/(238)U ratio between hair and nail samples was 0.98, and between hair and nails and urine the ratio was 0.91 and 0.89, respectively. The correlation of the ratio between water and the hair or nails was 0.97 but only 0.72 for water and urine, possibly due to spectral interferences. These results conclusively demonstrated that the uranium found in the bioassays can be traced to the drinking water, thus providing a direct link to the source of exposure. Hair may serve as an excellent indicator of occupational or environmental exposure to uranium and provide information regarding its source. Bioassay of hair is attractive as it is an effective bio-concentrator, samples can be easily stored, the concentration reflects an integrated value, and, finally, the measurement of the (234)U/(238)U isotopic ratio in digested hair samples by MC-ICPMS is feasible and highly informative. Hair bioassay can also be used to assess exposure to depleted uranium long after the subjects have left the area suspected of contamination.

Body Burden↗

PubMed2001

Uranium bioassay--beyond urinalysis.

Assessment of occupational or environmental exposure to uranium compounds is largely based on urinalysis. However, urine samples generally reflect either recent exposure (within a few days after an incident) or chronic exposure and, furthermore, diurnal fluctuations in "spot samples" make it difficult to estimate the extent of the internal dose received. Thus, if urine samples are not collected within a relatively short time after accidental exposure or if the samples are not representative due to collection logistics, internal dosimetry calculations based only on urinalysis may be misleading. With the advent of efficient and sensitive methods for determination of uranium in hair and nails, some of these drawbacks may be overcome. It is proposed that with little additional cost, determination of the uranium in hair may yield better insights for internal dosimetry of uranium exposure.

Circadian Rhythm↗

PubMed2001

The role of trace elements in psoriatic patients undergoing balneotherapy with Dead Sea bath salt.

BACKGROUND: A beneficial effect was observed in patients with psoriasis vulgaris following balneotherapy with Dead Sea bath salt. OBJECTIVES: To evaluate the possible role of trace elements in the effectiveness of balneotherapy. METHODS: Serum levels of 11 trace elements were analyzed in 23 patients with psoriasis vulgaris who participated in a double-blind controlled study of balneotherapy with either Dead Sea bath salt (12 patients) or common salt (11 patients). Thirteen healthy volunteers served as controls. RESULTS: The mean pre-treatment serum levels of boron, cadmium, lithium and rubidium were significantly lower in patients compared to controls, whereas the mean pre-treatment serum level of manganese was significantly higher in patients compared to controls. Balneotherapy with Dead Sea bath salt resulted in a significant decrease (P = 0.0051) in the mean serum level of manganese from 0.10 +/- 0.05 mol/L to 0.05 +/- 0.02 mumol/L. The mean reduction in the serum level of manganese differed significantly (P = 0.002) between responders (% Psoriasis Area and Severity Index score reduction > or = 25) and non-responders (% PASI score reduction < 25). Following balneotherapy with Dead Sea bath salt the mean serum level of lithium decreased in responders by 0.01 +/- 0.02 mumol/L, whereas its level in non-responders increased by 0.03 +/- 0.03 mumol/L. (P = 0.015). CONCLUSIONS: Manganese and lithium may play a role in the effectiveness of balneotherapy with Dead Sea bath salt for psoriasis.

Adult↗

PubMed2000

NPS 1506: a novel NMDA receptor antagonist: neuroprotective effects in a model of closed head trauma in rats.

We examined whether NPS 1506, a novel uncompetitive N-methyl-D-aspartate receptor antagonist, influences neurological outcome following closed head trauma (CHT) in rats. One hundred ten rats were divided into 11 groups: CHT (yes/no), treatment with NPS 1506 (yes/no), and time of euthanization (24 h/48 h). The dose of NPS 1506 was 1 mg/kg IV at 1 and 4 hours following CHT or sham operation. Closed head trauma induced the following changes in the injured hemisphere: Decreased specific gravity (sg) (1.036 +/- 0.006) and magnesium (Mg) (0.042 +/- 0.005 microg/mg) at 24 hours, and potassium (K) at 24 (1.145 +/- 0.376 microg/mg) and 48 hours, and increased water content (W) (84.9 +/- 2.5%) and sodium (Na) (2.135 +/- 0.699 microg/mg) at 24 hours, and calcium (Ca) at 24 (0.543 +/- 0.157 microg/mg) and 48 hours. These were reversed by NPS 1506; sg of 1.043 +/- 0.004, Mg of 0.077 +/- 0.009 microg/mg, K of 1.930 +/- 0.238 microg/mg, W of 81.5 +/- 1.9%, Ca of 0.043 +/- 0.023 microg/mg, and Na of 0.688 +/- 0.110 microg/mg. In groups not given NPS 1506, a nonsignificant decrease in neurological severity score (NSS) occurred at 24 and 48 hours as compared to NSS at 1 hour after CHT. In groups given NPS 1506, NSS at 24 and 48 hours decreased significantly (improved) compared to NSS at 1 hour, but not compared to NSS at 24 and 48 hours in groups not given NPS 1506. NPS 1506 caused no significant change in ischemic tissue volume or hemorrhagic necrosis volume in the injured hemisphere at 24 hours or 48 hours. These findings indicate that NPS 1506 improved measures of brain tissue edema (at 24 hours but not at 48 hours) and ion homeostasis, and this improvement was not related to other measures of outcome.

Animals↗

PubMed1999

Atmospheric pressure chemical ionization of fluorinated phenols in atmospheric pressure chemical ionization mass spectrometry, tandem mass spectrometry, and ion mobility spectrometry.

Atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) for fluorinated phenols (C6H5-xFxOH Where x = 0-5) in nitrogen with Cl- as the reagent ion yielded product ions of M Cl- through ion associations or (M-H)- through proton abstractions. Proton abstraction was controllable by potentials on the orifice and first lens, suggesting that some proton abstraction occurs through collision induced dissociation (CID) in the interface region. This was proven using CID of adduct ions (M Cl-) with Q2 studies where adduct ions were dissociated to Cl- or proton abstracted to (M-H)-. The extent of proton abstraction depended upon ion energy and structure in order of calculated acidities: pentafluorophenol > tetrafluorophenol > trifluorophenol > difluorophenol. Little or no proton abstraction occurred for fluorophenol, phenol, or benzyl alcohol analogs. Ion mobility spectrometry was used to determine if proton abstraction reactions passed through an adduct intermediate with thermalized ions and mobility spectra for all chemicals were obtained from 25 to 200 degrees C. Proton abstraction from M Cl- was not observed at any temperature for phenol, monofluorophenol, or difluorophenol. Mobility spectra for trifluorophenol revealed the kinetic transformations to (M-H)- either from M Cl- or from M2 Cl- directly. Proton abstraction was the predominant reaction for tetra- and penta-fluorophenols. Consequently, the evidence suggests that proton abstraction occurs from an adduct ion where the reaction barrier is reduced with increasing acidity of the O-H bond in C6H5-xFxOH.

Atmospheric Pressure↗

PubMed1998

Uranium in urine--normalization to creatinine.

"Spot samples" of urine are routinely used to monitor occupational exposure to uranium and other toxic heavy metals, such as mercury, lead, and cadmium. In the present work, it was shown that diurnal variations in the uranium concentration in different urine samples from the same individual could be quite large. However, these variations were in correlation to the creatinine level of the same samples, with values of R = 0.72-0.99, for the five subjects studied here. Thus, it is proposed here that uranium concentrations in "spot" urine samples be expressed in terms of ng uranium g(-1) creatinine rather than ng uranium L(-1). Once the 24-h creatinine level is estimated for the individual based on weight, height and age, the adjusted values can be used for determination of the internal dose of uranium.

Circadian Rhythm↗

PubMed1998

Uptake of ingested uranium after low "acute intake".

The uptake of uranium, ingested as a soluble compound, was studied by monitoring the uranium level in urine by inductively coupled plasma mass spectrometry and through measurement of an isotopic tracer. The high sensitivity of this method allows measurement of uranium levels in urine samples from each voiding, therefore more detailed biokinetic studies are possible. To simulate low "acute intake," five volunteers with "normal" levels (5-15 ng L(-1)) of uranium in urine ingested a grapefruit drink spiked with 100 microg of uranium (235U/238U = 0.245%) as uranyl nitrate, and the level of uranium in their urine after ingestion was monitored. Two techniques were applied to estimate the extent of exposure: a) uranium levels above the normal level for each volunteer; and b) the deviation from natural isotopic ratio. Results were normalized relative to the creatinine concentration, which served as an indicator of urine dilution, to reduce effects due to diurnal changes. The results clearly indicate that currently accepted bio-kinetic models overestimate the time between ingestion of dissolved uranium and its excretion in urine, the maximum of which was found to be around 6-10 h. The uptake fraction was in agreement with recent studies, i.e., 0.1-0.5% of the ingested uranium for four of the subjects but above 1.5% for the fifth, and well below the 5% reported in International Commission on Radiation Protection Publication 54. Finally, partial results from the isotope dilution study indicate that uranium absorbed through the intestine interchanges with uranium retained in body organs. The time scale of this process is quite short, and the acute exposure led to a minimum in the isotopic ratio within hours, while recovery back to natural abundance due to low chronic exposure takes several days.

Adult↗

PubMed1996

Inductively coupled plasma mass spectrometry as a simple, rapid, and inexpensive method for determination of uranium in urine and fresh water: comparison with LIF.

A simple method, based on inductively coupled plasma mass spectrometry, for determination of uranium in urine at levels that indicate occupational exposure, is presented. Sample preparation involves a fifty-fold dilution of the urine by nitric acid (2% HNO3) and no other chemical treatment or separation. The analysis itself is completed in under 3 min. The analytical procedure is fully automated so that a technician may perform over 100 analyses per day. With proper control of the blank contribution, a lower limit of detection of 3 ng L(-1) in the original urine sample was achieved. Uranium concentrations in the range 6-30 ng L(-1) were found in urine samples of people that are not occupationally exposed. The validity of the results was demonstrated through measurement of standards, controlled uranium addition experiments and, at higher concentrations, by comparison with results obtained by an independent method based on laser induced fluorescence. The laser induced fluorescence technique was found to be sufficient for detection of occupational exposure at an action level of 1.5 microg L(-1). Use of internal standards, indium, and thallium, improved quantification by about 10%, but was not deemed necessary for routine analysis. The inductively coupled plasma mass spectrometry is also ideally suited for monitoring uranium in fresh water and drinking water, as no sample dilution is required and the lower limit of detection is below 0.15 ng L(-1).

Humans↗