Human factors testing of the Quanta SC+ hemodialysis system: An innovative system for home and clinic use.

INTRODUCTION: Uptake rates of home hemodialysis are the lowest among all modality types, despite providing patients with clinical and quality of life benefits at a lower cost to providers. Currently, there is a need to develop dialysis systems that are appealing to patients while also being suitable for use across the continuum of care. The SC+ hemodialysis system was developed by Quanta Dialysis Technologies Ltd. to provide patients with a dialysis system that is small, simple to use, and powerful enough to deliver acceptable dialysis adequacy. METHODS: As part of the SC+ design validation, human factors testing was performed with 17 Healthcare Professionals (nephrology nurses and healthcare assistants) and 15 Home Users (patients and caregivers). To assess usability and safety, the human factors testing involved between 4.5 and 6 hours of training and, after a period of training decay, a subsequent test session in which participants independently performed tasks on SC+. FINDINGS: Between the two user groups, there were only 29 errors observed out of 1216 opportunities for errors, despite minimal training. Errors that did occur were minor and attributed to an initial lack of familiarity with the device; none were safety related. DISCUSSION: Among prevalent dialysis patients and healthcare professionals, the SC+ hemodialysis system was easy to use, even with minimal training and a learning decay period, and had a high level of use safety. By taking into account human factors to optimize the user experience, SC+ has the potential to address systemic and patient barriers, allowing for wider self-care and home hemodialysis adoption.

Influence of perioperative complication severity on 1- and 2-year outcomes of low back surgery.

BACKGROUND: Several factors potentially influence outcomes of surgery, including perioperative complications. Complications may take many forms and the Clavien-Dindo (CD) classification is designed to categorize them by degree of severity. The aim of this study was to evaluate the influence of perioperative complications by severity categorization on the 1-and 2-year pain and disability outcomes for patients who received low back surgery. MATERIALS AND METHODS: Data used for the study involved a purposive sample (N = 477; 8.1%) from a spine outcomes registry of 5876 patients who received spine surgery and encountered complications. All complications were categorized using the CD classification and were collapsed according to distribution frequencies, i.e., Grade I-II and Grade III-V. Adjusted and unadjusted regression analyses were used to determine the association between CD classification and 1- and 2-year outcomes. RESULTS: The majority of surgical complications were Grade III-V (N = 358; 75.1%), with two incidences in which death occurred. For the unadjusted models, there were no significant associations between CD classification categorizations for 1-year outcomes; however, 2-year outcomes were significantly worse (P <0.05) for those with Grade III-V categorization. When adjusted and controlled for baseline characteristics, CD classification did not influence 1-or 2-year pain and disability outcomes. CONCLUSIONS: When control variables are considered, the severity of perioperative surgical complications does not appear to influence 1- or 2-year pain and disability outcomes. LEVEL OF EVIDENCE: Level 4.

The potential of pulsed low intensity ultrasound to stimulate chondrocytes matrix synthesis in agarose and monolayer cultures.

Pulsed low intensity ultrasound (PLIUS) has been used successfully for bone fracture repair and has therefore been suggested for cartilage regeneration. However, previous in vitro studies with chondrocytes show conflicting results as to the effect of PLIUS on the elaboration of extracellular matrix. This study tests the hypothesis that PLIUS, applied for 20 min/day, stimulates the synthesis of sulphated glycosaminoglycan (sGAG) by adult bovine articular chondrocytes cultured in either monolayer or agarose constructs. For both culture models, PLIUS at either 30 or 100 mW/cm(2) intensity had no net effect on the total sGAG content. Although PLIUS at 100 mW/cm(2) did induce a 20% increase in sGAG content at day 2 of culture in agarose, this response was lost by day 5. Intensities of 200 and 300 mW/cm(2) resulted in cell death probably due to heating from the ultrasound transducers. The lack of a sustained up-regulation of sGAG synthesis may reflect the suggestion that PLIUS only induces a stimulatory effect in the presence of a tissue injury response. These results suggest that PLIUS has a limited potential to provide an effective method of stimulating matrix production as part of a tissue engineering strategy for cartilage repair.

A gas chromatography-isotope dilution high-resolution mass spectrometry method for quantification of isomeric benzo[a]pyrene diol epoxide hemoglobin adducts in humans.

We developed a gas chromatography-isotope dilution high-resolution mass spectrometry (GC-ID-HRMS) method for quantifying isomers of benzo[a]pyrene (BaP) tetrol metabolites resulting from hydrolysis of benzo[a]pyrene-diol-epoxide hemoglobin (BaPDE-Hb) adducts. Acid hydrolysis of BPDE-Hb adducts extracted from human blood samples yielded isomers of benzo[a]pyrene-tetrahydrotetrols, (+/-)-BaP-r-7,t-8,t-9,c-10-tetrol (BPTI-1), (+/-)-BaP-r-7,t-8,t-9,t-10-tetrol (BPTI-2), (+/-)-BaP-r-7,t-8,c-9,t-10-tetrol (BPTII-1), and (+/-)-BaP-r-7,t-8,c-9,c-10-tetrol (BPTII-2). The isomeric BaP tetrols were isolated from the matrix by liquid-liquid extraction, and then further purified by solid-phase extraction. Following silylation with N-methyl-N-(trimethylsilyl)-trifluoroacetamide, the analytes were measured by GC-HRMS, using electron ionization. We have found detectable concentrations in the low fmol range for BPTII-1 and BPTI-1 in all donors tested. The mean BaP adduct levels for smoking donors (n = 9) were 0.022 fmol/mg hemoglobin for BPTII-1 and 0.070 fmol/mg hemoglobin for BPTI-1. The mean BaP adduct levels with hemoglobin for non smoking donors (n = 6) was 0.021 fmol/mg hemoglobin for BPTII-1 and 0.105 fmol/mg hemoglobin for BPTI-1.

Levels of 1-hydroxypyrene and other monohydroxy polycyclic aromatic hydrocarbons in children: a study based on U.S. reference range values.

Urine samples collected in 1999 and 2000 as part of the National Health and Nutrition Examination Survey (NHANES) were analyzed for 14 monohydroxy polycyclic aromatic hydrocarbons (PAH, metabolites of 7 PAH compounds) and for the first time reference range values were calculated for these metabolites in the U.S. population. The purpose of this paper is to explore differences in these PAH metabolites between children (6-11 years old), adolescents, and adults. More than 99% of the urine samples contained a detectable amount of 1-hydroxypyrene (1-OHpyrene), a metabolite of pyrene. We found that children in the youngest age group (6-11 years) had a geometric mean level (creatinine corrected data) 30% higher than children and adults in the other age groups, but no statistical differences existed between the two genders and among different racial groups. Smokers and persons exposed to environmental tobacco smoke (ETS) in 12-19-year-old group and the 20-year-and-older group had higher levels of urinary 1-OHpyrene by a factor of 2-3 than non-smokers in the corresponding age group. Measurements of 3-hydroxyphenanthrene also suggested increased levels in children and in smokers. These results may indicate that young children are at a greater risk for PAH exposure, or that they absorb, distribute, metabolize, or eliminate PAH differently than adults.

Reference range levels of polycyclic aromatic hydrocarbons in the US population by measurement of urinary monohydroxy metabolites.

We developed a gas chromatography isotope-dilution high-resolution mass spectrometry (GC/ID-HRMS) method for measuring 14 polycyclic aromatic hydrocarbon (PAH) metabolites representing seven parent PAHs in 3 mL of urine at low parts-per-trillion levels. PAH levels were determined in urine samples collected in 1999 and 2000 from approximately 2400 participants in the National Health and Nutrition Examination Survey, and, for the first time, reference range values were calculated for these metabolites in the US population. Using this GC/ID-HRMS method, we found detectable concentrations for monohydroxy metabolite isomers of fluorene, phenanthrene, fluoranthene, pyrene, and chrysene, benzo[c]phenanthrene, and benz[a]anthracene. Some monohydroxy metabolite isomers of benzo[c]phenanthrene, chrysene, and benz[a]anthracene exhibited low detection frequencies that did not allow for geometric mean calculations. Our study results enabled us to establish a reference range for the targeted PAHs in the general US population.

Uses of speciation techniques in biomonitoring for assessing human exposure to organic environmental chemicals.

Speciation analysis has been used for many years to identify and measure different forms of a given chemical in environmental and human samples. Although the term "speciation" is generally applied to the measurement of inorganic chemicals, the term can also be applied to many measurements of organic chemicals in complex samples, such as environmental media and biological matrices. We present several examples of achieving speciation analysis by selecting the appropriate biological matrix in which to measure a specific chemical(s), by a given analytical method, for the most accurate assessment of human exposure to the environmental chemical. Much of this information and many of these techniques are transferable to the measurement of inorganic elements in environmental and biological samples.

Comparison of 1-hydroxypyrene exposure in the US population with that in occupational exposure studies.

Urine samples collected in 1999 and 2000 as part of the National Health and Nutrition Examination Survey (NHANES) were analyzed for 14 monohydroxy polycyclic aromatic hydrocarbons (PAHs), and, for the first time, reference range values were calculated for these metabolites in the US population. Pyrene is a major component of most PAH mixtures and often is used as a surrogate for total PAH exposure. We detected 1-hydroxypyrene (1-OHpyrene), a metabolite of pyrene, in more than 99% of the samples. The overall geometric mean concentration for 1-OHpyrene in the USA was 79.8 ng/l, with a 95% confidence interval (CI) of 69.0-92.2 ng/l. The overall geometric mean creatinine-adjusted urinary 1-OHpyrene levels in the USA was 74.2 ng/g creatinine (0.039 micromol/mol), with a 95% CI of 64.1-85.9 ng/g creatinine (0.034-0.046 micromol/mol). There were no statistically significant differences among age, gender, or race/ethnicity groups. Adult smokers in the USA have urinary 1-OHpyrene levels three times higher than those of non-smokers. This difference was statistically significant. In this paper, we compare the reference range of urinary 1-OHpyrene levels with levels reported from various occupations by other researchers.

Biomonitoring of chemical exposure among New York City firefighters responding to the World Trade Center fire and collapse.

The collapse of the World Trade Center (WTC) on 11 September 2001 exposed New York City firefighters to smoke and dust of unprecedented magnitude and duration. The chemicals and the concentrations produced from any fire are difficult to predict, but estimates of internal dose exposures can be assessed by the biological monitoring of blood and urine. We analyzed blood and urine specimens obtained from 321 firefighters responding to the WTC fires and collapse for 110 potentially fire-related chemicals. Controls consisted of 47 firefighters not present at the WTC. Sampling occurred 3 weeks after 11 September, while fires were still burning. When reference or background ranges were available, most chemical concentrations were found to be generally low and not outside these ranges. Compared with controls, the exposed firefighters showed significant differences in adjusted geometric means for six of the chemicals and significantly greater detection rates for an additional three. Arrival time was a significant predictor variable for four chemicals. Special Operations Command firefighters (n = 95), compared with other responding WTC firefighters (n = 226), had differences in concentrations or detection rate for 14 of the chemicals. Values for the Special Operations Command firefighters were also significantly different from the control group values for these same chemicals and for two additional chemicals. Generally, the chemical concentrations in the other firefighter group were not different from those of controls. Biomonitoring was used to characterize firefighter exposure at the WTC disaster. Although some of the chemicals analyzed showed statistically significant differences, these differences were generally small.

Determination of selected monohydroxy metabolites of 2-, 3- and 4-ring polycyclic aromatic hydrocarbons in urine by solid-phase microextraction and isotope dilution gas chromatography-mass spectrometry.

Eighteen monohydroxy polycyclic aromatic hydrocarbon metabolites (OH-PAHs) representing polycyclic aromatic hydrocarbons (PAHs) containing up to four rings in human urine have been measured. The method includes the addition of carbon-13 labeled internal standards, enzymatic hydrolysis, and solid-phase microextraction followed by gas chromatography with high-resolution mass spectrometry. By using response factors calculated with the carbon-13 labeled standards, results are presented for calibration, relative standard deviations and analyte levels from an unspiked human urine pool. The method detection limits ranged from 0.78 ng/l for hydroxyphenanthrenes to 15.8 ng/l for 1-hydroxynaphthalene, and the recoveries ranged between 6% for hydroxychrysene and 47% for 1-hydroxypyrene. The relative standard deviation was lowest for 3-hydroxyphenanthrene at 2.4% and went up to 18.7% for 6-hydroxychrysene. The method was calibrated from 10 to 1200 ng/l. Eleven of the 18 metabolites were found in background pooled urine samples. This validated method is a convenient and reliable tool for determining urinary OH-PAHs as biomarkers of exposure to eight PAHs.

Quantification of monohydroxy-PAH metabolites in urine by solid-phase extraction with isotope dilution-GC-MS.

For measurement of biomarkers from polycyclic aromatic hydrocarbon (PAH) exposure, an analytical method is described quantifying hydroxylated PAH (OH-PAH) in urine samples. This method determined monohydroxy metabolites of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, benzo[c]phenanthrene, and benz[a]anthracene. The sample preparation consisted of enzymatic hydrolysis, solid-phase extraction and derivatization with a silylating reagent. Five carbon-13 labeled standards were used for isotope dilution. Analytes were separated by gas chromatography (GC) and quantified with high-resolution mass spectrometry (HRMS). This method produced good recoveries (41-70%), linearity, and specificity. Data were corrected for blank levels from the naphthalene, fluorene, and phenanthrene metabolites. Method detection limits ranged from 2 ng L(-1) for 1-hydroxypyrene to 43.5 ng L(-1) for 1-hydroxynaphthalene. Using quality control charts from two urine pools, the method can be readily applied to biomonitoring PAH exposure.