Selective pulmonary vasodilation improves ventriculovascular coupling and gas exchange in a patient with unrepaired single-ventricle physiology.

We describe a 63-year-old patient with unrepaired tricuspid valve atresia and a hypoplastic right ventricle (single-ventricle physiology) who presented with progressive symptomatic hypoxia. Her anatomy resulted in parallel pulmonary and systemic circulations, pulmonary arterial hypertension, and uncoupling of the ventricle/pulmonary artery. Hemodynamic and coupling data were obtained before and after pulmonary vasoactive treatment, first inhaled nitric oxide and later inhaled treprostinil. The coupling ratio (ratio of ventricular to vascular elastance) shunt fractions and dead space ventilation were calculated before and after treatment. Treatment resulted in improvement of the coupling ratio between the ventricle and the vasculature with optimization of stroke work, equalization of pulmonary and systolic flows, a decrease in dead space ventilation from 75% to 55%, and a significant increase in 6-minute walk distance and improved hypoxia. Inhaled treprostinil significantly increased 6-minute walk distance and improved hypoxia. This is the first report to show that pulmonary vasoactive treatment can be used in a patient with unrepaired single-ventricle anatomy and describes the hemodynamic effects of inhaled therapy on ventriculovascular coupling and gas exchange in the pulmonary circulation in this unique physiology.

Apparent copper absorption from a vegetarian diet.

BACKGROUND: Vegetarian diets often contain more copper than do nonvegetarian diets, but observations of decreased plasma copper associated with vegetarian diets suggest that these diets have lower copper bioavailability than do nonvegetarian diets. OBJECTIVE: Our objective was to determine apparent copper absorption from controlled lactoovovegetarian and nonvegetarian diets. DESIGN: Eighteen women aged 20-43 y consumed lactoovovegetarian and nonvegetarian weighed diets for 8 wk each in a randomized, crossover design. The lactoovovegetarian and nonvegetarian diets provided 1.45 and 0.94 mg Cu, 38 and 16 g dietary fiber, and 1584 and 518 mg phytic acid, respectively, per 9.2 MJ (2200 kcal). After the women had been consuming each diet for 4 wk, their apparent copper absorption was determined by measuring the fecal excretion of the 65Cu stable isotope, extrinsically added to the entire menu as 65CuCl2. RESULTS: Plasma copper and ceruloplasmin were not affected by diet. The efficiency of apparent copper absorption from the lactoovovegetarian diet was less (33%) than that from the nonvegetarian diet (42%) (pooled SD: 9%; P < 0.05). However, because the lactoovovegetarian diet contained approximately 50% more copper, the total apparent copper absorption from the lactoovovegetarian diet (0.48 mg/d) was greater than that from the nonvegetarian diet (0.40 mg/d) (pooled SD: 0.09 mg; P < 0.05). CONCLUSION: Although copper was less efficiently absorbed from a vegetarian diet than from a nonvegetarian diet, total apparent copper absorption was greater from the vegetarian diet because of its greater copper content.

Cadmium absorption in women fed processed edible sunflower kernels labeled with a stable isotope of cadmium, (113)Cd.

The apparent fractional absorption of cadmium (Cd) from sunflower kernels (SFK) was determined in women volunteers by using kernels labeled with a stable isotope of Cd ((113)Cd) by injecting it into the flowering head. Fourteen women who were between the ages of 30 and 70 years, who did not use tobacco products, who were in good health, and who had been consuming a self-selected diet low in Cd content participated in the study. The volunteers were fed a breakfast composed primarily of cereal, milk, and fruit juice. The breakfast also contained a portion of (113)Cd-labeled SFK processed into a buttery spread. Each volunteer collected individual stool samples for 21 days beginning immediately after they had consumed the labeled kernels. The total amounts of Cd and (113)Cd excreted in each stool were determined by isotope dilution inductively coupled plasma mass spectrometry. Mean fecal Cd excretion was 14.1+/-4.1 microg/day and mean (113)Cd absorption was 10.6+/-4.4%. In agreement with previous studies, no significant (P>0.3) correlation between Cd absorption and serum ferritin concentrations was found in women whose serum ferritin concentrations were >25 ng/mL. These data suggest that the availability of Cd from highly processed sunflower kernels to humans is similar to that reported for other types of food.

Cadmium bioavailability from edible sunflower kernels: a long-term study with men and women volunteers.

Sunflower kernels (SFK) contain natural Cd in somewhat higher amounts than most other foods. This study was designed to determine if a change in the body burden of Cd could be measured in volunteers who consumed a controlled amount of SFK for 48 weeks. Healthy men and women between 23 and 59 years of age were divided into three groups each by age, sex, and weight. For 48 weeks, one group consumed 255 g (9 oz) of SFK/week, a second group consumed 113 g SFK and 142 g peanuts/week, and a third group consumed 255 g peanuts/week. SFK contained 0.52 microg Cd/g and peanuts contained 0.11 microg Cd/g. The consumption of 255 g SFK/week increased the average estimated intake of Cd from approximately 65 to approximately 175 microg/week. Although the consumption of Cd-containing SFK significantly increased the estimated Cd intake, there were no significant changes in Cd concentration in red blood cells, Cd excretion in the urine, or Cd concentrations in new hair growth. However, fecal Cd excretion significantly increased as the amount of SFK consumption increased. N-Acetyl-beta-D-glucosaminidase, a marker for kidney dysfunctions, was not significantly changed by consuming SFK-Cd. Overall, the results suggest that the consumption of Cd in the form of SFK at 9 oz (255 g)/week for 48 week had no adverse effect on the body burden of Cd.

Experimental methodologies and preliminary transfer factor data for estimation of dermal exposures to particles.

Developmental efforts and experimental data that focused on quantifying the transfer of particles on a mass basis from indoor surfaces to human skin are described. Methods that utilized a common fluorescein-tagged Arizona Test Dust (ATD) as a possible surrogate for housedust and a uniform surface dust deposition chamber to permit estimation of particle mass transfer for selected dust size fractions were developed. Particle transfers to both wet and dry skin were quantified for contact events with stainless steel, vinyl, and carpeted surfaces that had been pre-loaded with the tagged test dust. To better understand the representativeness of the test dust, a large housedust sample was collected and analyzed for particle size distribution by mass and several metals (Pb, Mn, Cd, Cr, and Ni). The real housedust sample was found to have multimodal size distributions (mg/g) for particle-phase metals. The fluorescein tagging provided surface coatings of 0.11-0.36 ng fluorescein per gram of dust. The predominant surface location of the fluorescein tag would best represent simulated mass transfers for contaminant species coating the surfaces of the particles. The computer-controlled surface deposition chamber provided acceptably uniform surface coatings with known particle loadings on the contact test panels. Significant findings for the dermal transfer factor data were: (a) only about 1/3 of the projected hand surface typically came in contact with the smooth test surfaces during a press; (b) the fraction of particles transferred to the skin decreased as the surface roughness increased, with carpeting transfer coefficients averaging only 1/10 those of stainless steel; (c) hand dampness significantly increased the particle mass transfer; (d) consecutive presses decreased the particle transfer by a factor of 3 as the skin surface became loaded, requiring approximately 100 presses to reach an equilibrium transfer rate; and (e) an increase in metals concentration with decreasing particle size, with levels at 25 microns typically two or more times higher than those at 100 microns--consistent with the earlier finding of Lewis et al. for the same sample for pesticides and polycyclic aromatic hydrocarbons (PAHs).

An automated system for producing uniform surface deposits of dry particles.

A laboratory system has been constructed that uniformly deposits dry particles onto any type of test surface. Devised as a quality assurance tool for the purpose of evaluating surface sampling methods for lead, it also may be used to generate test surfaces for any contaminant that uses particles or dust as a transport mechanism. Additionally, it may be used to spike surfaces for studies concerning particle transport, resuspension, reentrainment, and exposure. The electromechanical system includes a rugged aluminum chamber housing deposition equipment, a computer-controlled positioning system, and a 0.61 x 0.61 m target surface area (2 x 2 ft). Media used to evaluate the system have included glass beads of various size fractions (physical diameters between 30 and 500 microm), and Arizona Test Dust (aerodynamic diameters between 1 and 80 microm). Presieved particle size fractions may be used individually to study the effects of monodisperse particles, or may be mixed to create custom polydisperse size distributions. Using arrays of 16 coupons placed on the surface to collect representative samples from every test, the uniformity of the particle deposition can be quantified. The system achieved an average coefficient of variation of less than 20% for the 16 coupons for the particle types and sizes mentioned above and for a variety of total surface loadings (0.3-19 g/m2). Calculations of the system's repeatability (as the average coefficient of variation of mass gains for individual coupon locations compared across multiple identically configured runs) yielded approximately 10 +/- 5% (one standard deviation). Tests of the system's accuracy, defined as the absolute percentage difference between predicted surface loadings and actual loadings, yielded 3.7 +/- 1.3% (one standard deviation).

Liquid-liquid extraction of cadmium by sodium diethyldithiocarbamate from biological matrixes for isotope dilution inductively coupled plasma mass spectrometry.

A published procedure for the liquid-liquid extraction of Cd by sodium diethyldithiocarbamate (NaDDC) was modified and tested on 12 biological matrixes of plant and animal origin for use with isotope dilution (ID) inductively coupled plasma mass spectrometry (ICPMS). The tested matrixes were reference materials, certified for Cd, and a feces in-house standard. The digested and extracted standards were analyzed for Cd stable isotopes by ICPMS and the resulting isotope ratios examined for isobaric and polyatomic interferences. Cadmium recoveries, after extraction, ranged from 73% to 20% and apparently were inversely related to Cd concentration, even in the presence of excess chelator. For each reference material, the measured isotope ratios for Cd were corrected for instrumental bias and compared to natural abundance Cd isotope ratios. Nonextracted samples had large isotope ratio deviations for all but one or two ratios. Extraction improved all the isotope ratios measured (lowered % error relative to natural abundances), but interferences were noted for a few samples. The extracted human in-house feces standard was found to have Sn signals reduced by 300-fold, but residual Sn concentrations still interfered with 116Cd, though not 112Cd or 114Cd. Thus, evaluation of the NADDC-extracted in-house fecal standard and reference materials indicate the successful removal of interferences that otherwise prevented accurate determinations of Cd by IDICPMS and show that a number of Cd isotope ratios could be accurately measured (< 1.5% error) for multiple stable isotope tracer studies in a broad range of NaDDC-extracted biological matrixes.

Selenium supplementation affects the retention of stable isotopes of selenium in human subjects consuming diets low in selenium.

Twenty-nine women and fifteen men from an area of low Se intake (South Island of New Zealand) consumed 100 micrograms stable 74Se, as selenate given in water after an overnight fast, and blood was collected for 3 weeks. They were then divided into five groups and supplemented with 0, 10, 20, 30 and 40 micrograms Se/d (as selenomethionine) for 5 months. After 5 months, they received a second dose of 74Se identical to the first. Supplementation significantly altered retention of 74Se in the plasma, but not in the erythrocytes or platelets. Subjects receiving the placebo retained the greatest amount, and subjects receiving 30 micrograms supplemental Se/d retained the least 74Se. Supplementation resulted in relatively more isotope being retained in a medium molecular mass protein considered to be albumin, and relatively less in another fraction considered to be selenoprotein P. The lack of many observed changes in retention of stable Se, and the shift in retention among the plasma proteins, suggests that supplemental Se was not being used to replete critical pools of Se, probably because of adaptation to low Se intake.

Cadmium burden of men and women who report regular consumption of confectionery sunflower kernels containing a natural abundance of cadmium.

Because of inherent genetic and physiological characteristics, the natural concentration of cadmium in the kernels of sunflowers grown in uncontaminated soils of the northern Great Plains region of the United States is higher than in most other grains. We tested the hypothesis that a habitual consumption of sunflower kernels will increase the body burden and health effects of cadmium in humans. Sixty-six men and women who reported consuming various amounts of sunflower kernels were recruited and divided by sex and kernel consumption: those who consumed less than or equal to 1 ounce(oz)/week and those who consumed more than 1 oz/week. Cadmium intake was assessed by calculation from 7-day food diaries, cadmium burden by whole blood cadmium, red blood cell (RBC) cadmium and urine cadmium concentrations, and health effects by urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) activity and beta2-microglobulin (beta2MG). The results showed that high intakes of sunflower kernels (>1 oz/day) significantly increased the intake of cadmium (p<0.004). However, the amount of cadmium in whole blood or RBCs was not affected by cadmium intake. Urinary excretion of cadmium also was not affected by cadmium intake. Urine NAG activity and the amount of urinary beta2MG were significantly elevated in the urine of high sunflower kernel consumers when the values were expressed on a urine volume basis (p<0.03), but not when expressed on a creatinine basis (p>0.05). Because normal ranges for the excretion of these protein markers have not been established, it was not possible to determine if these elevated values were meaningful. However, given the knowledge that habitual consumption of sunflower kernels with natural cadmium concentrations higher than most other food products will increase the average intake of dietary cadmium, the potential exists for an increased body burden of cadmium. Controlled feeding studies in humans should be pursued in order to determine if the body burden does indeed increase and, if so, is it a cause for concern.

Use of stable isotopic selenium as a tracer to follow incorporation of selenium into selenoproteins.

Stable isotopes of selenium (Se) have been used in human studies to measure Se absorption, retention and excretion. The purpose of this study was to examine whether stable Se could also be used to follow the incorporation of Se into selenoproteins and whether selenoproteins are labeled with stable isotopes the same way they are with radioactive Se. Rats fed either a Se-deficient or a high-Se diet were injected with either a radioactive (75Se) or a stable isotope of Se (77Se), and the liver cytosol was chromatographed on Sephadex G-200. Compared with 75Se, a greater percentage of 77Se was incorporated into cytosol, but the distribution and the effect of dietary Se was similar for both isotopes. New Zealand long-eared rabbits were also injected with either 77Se or 75Se, and the plasma was chromatographed. More of the 75Se was incorporated into the plasma, but again the patterns of incorporation were similar for both isotopes. Plasma from a male subject who ingested 60 micrograms of 77Se was chromatographed, and the stable Se was detected in column fractions and showed a distribution similar to that observed for rabbit plasma. Finally, a polyacrylamide gel electrophoresis (PAGE) method was developed that allowed loading of sufficient protein to analyze for 77Se in individual protein fractions. The distribution of 77Se and 75Se in rabbit plasma was similar. Human plasma was electrophoresed by a similar method and peaks of 56 and 23 kDa were detected. These data show that stable isotopes of Se can be used for selenoprotein production in the same way as radioactive isotopes. They also show that, when physiological amounts of stable Se are ingested by humans, the isotope can be detected in blood-borne proteins separated by column chromatography and PAGE.

Retrospective evaluation of admission criteria for paediatric electrical injuries.

In the medical community, the practice of admitting all electrical burns for 24-48 h of observation, monitoring and laboratory evaluation is widespread. This retrospective review of paediatric electrical burns was conducted to determine which patients may safely be treated as outpatients. Retrospective analysis of all paediatric burns admitted between 1980 and 1991 identified 35 patients with electrical injuries. Patients were divided into two groups for analysis: those burned by exposure to household voltages (120-240 V; n = 26) and those exposed to high voltages, in excess of 1000 V (n = 9). The majority of household electrical injuries occurred secondary to contact with the household 120 V (21/26). Contact with an extremity accounted for the largest number of these injuries (18/26). The mouth was the second most frequent site of injury (7/26). Most of these patients (20/26) had < 1 per cent BSA burn. No patient in the household-voltage group had an arrythmia that required treatment, nor were there any identified examples of compartment syndrome or other vascular complications. Seven patients did require minimal skin grafting. No deaths occurred in either group. The patients in the household-voltage group were significantly younger. High-voltage electrical injuries occurred in an older patient population and required more aggressive care and surgical intervention. This was evident at the time of initial evaluation. Based on these data, healthy children with small partial-thickness electrical burns and no initial evidence of cardiac or neurovascular injury do not appear to need hospital admission.

Use of inductively coupled plasma-mass spectrometry in boron-10 stable isotope experiments with plants, rats, and humans.

The commercial availability of inductively coupled plasma-mass spectrometry technology (ICP-MS) has presented the opportunity to measure the boron concentrations and isotope ratios in a large number of samples with minimal sample preparation. A typical analytical sequence for fecal samples consists of 25 acid blanks, 1 digestion blank, 5 calibration solutions, 4 standard reference material solutions, 10 samples, and 4 natural abundance bias standards. Boron detection limits (3 x 1 sigma) for acid blanks are 0.11 ppb for 10B, and 0.40 ppb for 11B. Isotope ratios were measured in fecal samples with 20 to 50 ppb boron with < 2% relative standard deviation. Rapid washout and minimal memory effects were observed for a 50 ppb beryllium internal standard, but a 200 ppb boron biological sample had a 1.0 ppb boron memory after a 6-min washout. Boron isotope ratios in geological materials are highly variable; apparently this variability is reflected in plants of a fixed natural abundance value for boron requires that a natural abundance ratio be determined for each sample or related data set. The natural abundance variability also prevents quantitation and calculation of isotope dilution by instrument-supplied software. To measure boron transport in animal systems, 20 micrograms of 10B were fed to a fasted rat. During the 3 days after a 10B oral dose, 95% of the 10B was recovered from the urine and 4% from the feces. Urinary isotope ratios, 11B/10B, changed from a natural abundance of 4.1140 to an enriched value of 0.95077, a 77% change.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of bile/pancreatic secretions on absorption of radioactive or stable zinc. In vivo and in vitro studies.

Biliary/pancreatic (B/P) secretions are a major component of endogenous secretions, and endogenously secreted Zn is a primary means of Zn homeostasis. This study examined whether B/P fluid alters the absorption/reabsorption of Zn and, in doing so, whether this contributes to homeostatic control of Zn. Animal experiments utilized rats fed 10 or 300 micrograms Zn/kg diet. An open-ended gut perfusion study in which 65Zn-labeled B/P fluid or 67Zn-labeled and digested diet found significantly decreased Zn absorption from B/P fluid. Although Zn absorption from both sources was less in animals fed diets higher in Zn, there was no interaction of treatment and diet. Further studies utilizing cultured human colon carcinoma cells (CACO-2) as in vitro models of gut enterocytes found that the presence of B/P fluid significantly decreased Zn retention and/or transport and resulted in a redistribution of cellular Zn after 1200 min of incubation. These studies show that a substance in B/P fluid can decrease the absorption of Zn and also suggest that dietary Zn and Zn associated with B/P secretions are absorbed from distinct pools. However, the lack of an interactive effect with diet, and the amount of time required to see differences in CACO-2 cells, suggest that differences in absorption are not a major contributor to Zn homeostasis.