Effect of phenylephrine on cerebral oxygen saturation and cardiac output in adults when used to treat intraoperative hypotension: a systematic review.

OBJECTIVE: The objective of this review was to examine the effect of phenylephrine on cerebral oxygen saturation, cardiac output, and middle cerebral artery blood flow velocity when used to treat intraoperative hypotension. INTRODUCTION: While the etiology of postoperative cognitive dysfunction in adults following surgery is likely multifactorial, intraoperative cerebral hypoperfusion is a commonly proposed mechanism. Research evidence and expert opinion are emerging that suggest phenylephrine adversely affects cerebral oxygen saturation and may also adversely affect cerebral perfusion via a reduction in cardiac output or cerebral vascular vasoconstriction. The administration of phenylephrine to treat intraoperative hypotension is common anesthesia practice, despite a lack of evidence to show it improves cerebral perfusion. Therefore, a systematic review of the effect of phenylephrine on cerebral hemodynamics has significant implications for anesthesia practice and future research. INCLUSION CRITERIA: Studies of adults 18 years and over undergoing elective, non-neurosurgical procedures involving anesthesia were included. In these studies, participants received phenylephrine to treat intraoperative hypotension. The effect of phenylephrine on cerebral oxygen saturation, cardiac output, or middle cerebral artery blood flow velocity was measured. METHODS: Key information sources searched included MEDLINE (Ovid), Embase, CINAHL (EBSCO), and Google Scholar. The scope of the search was limited to English-language studies published from 1999 through 2017. The recommended JBI approach to critical appraisal, study selection, data extraction, and data synthesis were used. RESULTS: This systematic review found that phenylephrine consistently decreased cerebral oxygen saturation values despite simultaneously increasing mean arterial pressure to normal range. Results also found that ephedrine and dopamine were superior to phenylephrine in maintaining or increasing values. Phenylephrine was found to be similar to vasopressin in the extent to which both decreased cerebral oxygen saturation values. Results also showed that phenylephrine resulted in statistically significant declines in cardiac output, or failed to improve abnormally low preintervention values. The effect of phenylephrine on middle cerebral artery blood flow velocity was only measured in one study and showed that phenylephrine increased flow velocity by about 20%. Statistical pooling of the study results was not possible due to the gross variation in how the intervention was administered and how effect was measured. CONCLUSIONS: This review found that phenylephrine administration resulted in declines in cerebral oxygen saturation and cardiac output. However, the research studies were ineffective in informing phenylephrine's mechanism of action or its impact on postoperative cognitive function. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO (CRD42018100740).

Ultrasonography relative to Cormack-Lehane in predicting difficult laryngoscopy: a systematic review of diagnostic test accuracy.

OBJECTIVE: The objective of this review is to determine the diagnostic test accuracy of point-of-care ultrasound anterior soft tissue quantification techniques for predicting difficult laryngoscopy in relation to Cormack-Lehane scores. INTRODUCTION: Difficult airway management is a critical challenge for anesthesia providers, and a non-invasive test to confidently predict difficult airway is lacking. When difficult airway is not anticipated, the provider's management of the event deteriorates, resulting in significant morbidity or mortality. This systematic review of the diagnostic efficacy of newer ultrasound techniques has potential to advance difficult airway prediction and patient safety. INCLUSION CRITERIA: This review will consider adults 18 years and older presenting for elective surgery, who undergo a preoperative point-of-care ultrasound anterior soft tissue airway examination that is referenced to an intraoperative Cormack-Lehane airway examination, obtained using direct laryngoscopy under general anesthesia. METHODS: Data sources will include Ovid MEDLINE, Trip Database, Embase, CINAHL Complete, Clinicaltrials.gov, Google Scholar, MedNar, Grey Literature Report, and ProQuest Dissertations and Theses. Only studies published in English after the advent of the Cormack-Lehane reference test (1984) will be included. Studies will be critically appraised using a checklist for studies of diagnostic test accuracy. Details about the index tests, populations, study methods, and outcomes of significance to the review will be extracted. Where possible, sensitivity and specificity will be pooled in statistical bivariate meta-analysis. Diagnostic thresholds will be displayed on a paired forest plot or summary receiver operator characteristic curve, depending on the degree of variability. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO CRD42020205974.

Transmission of novel Klebsiella pneumoniae carbapenemase-producing Escherichia coli sequence type 1193 among residents and caregivers in a community-based, residential care setting-Nevada, 2018.

We describe transmission of Klebsiella pneumoniae carbapenemase-producing Escherichia coli sequence type (ST) 1193 in a group home. E. coli ST1193 is an emerging multidrug-resistant clone not previously shown to carry carbapenemases in the United States. Our investigation illustrates the potential of residential group homes to amplify rare combinations of pathogens and resistance mechanisms.

Post-discharge interventions to enhance coping skills for survivors of stroke and their caregivers: a scoping review protocol.

OBJECTIVE: This scoping review aims to map the use of post-discharge interventions to enhance coping skills for adult stroke survivors and their informal caregivers. INTRODUCTION: Evidence shows that when stroke survivors and their informal caregivers are provided with post-discharge coping training, their outcomes improve. There is also evidence that healthcare providers currently focus on medication compliance and deliver little to no instruction on post-discharge coping interventions. As a result, more than 40% of stroke survivors and informal caregivers report a lack of awareness and access to community-based coping training once discharged from the hospital setting. INCLUSION CRITERIA: This scoping review will map the delivery modes, intervention types, locations, leadership and settings of current coping interventions for community-dwelling adults 18 years or older living with the effects of stroke and their informal caregivers. This review will be restricted to studies published in English that include interventions that are not reimbursed as part of United States healthcare coverage. METHODS: The search will include CINAHL, Cochrane Library, Embase, JBI Evidence Synthesis, MEDLINE, PEDro, PLoS, PsycINFO, and Web of Science. In addition, smaller health-related databases, stroke and rehabilitation journals, gray literature and stakeholder organization websites will be searched. A three-step search strategy will be utilized, including use of citation software to manage search results and de-duplication, abstract review and full-text review by two reviewers. Details of included studies will then be imported into information management software. The resulting map will be displayed in tabular form along with a narrative summary.

The effect of phenylephrine on cerebral perfusion when used to treat anesthesia-induced hypotension: a systematic review protocol.

REVIEW QUESTION: The question of this review is: What is the effect of intravenous phenylephrine on cerebral perfusion in adult patients when administered to treat anesthesia-induced hypotension?

Improving Patient Outcomes Through Closed-Claims Analysis: Salient Characteristics and Patterns Associated With Respiratory Events.

A retrospective, exploratory research design was used to analyze salient characteristics and patterns associated with closed claims involving Certified Registered Nurse Anesthetists (CRNAs) in which a respiratory event caused the adverse outcome. Alleged malpractice acts found in these claims occurred between 2003 and 2012. Respiratory events were the most frequent cause of adverse outcomes in the current database (34%). The respiratory adverse outcomes often resulted in mortality or significant and permanent morbidity (69%) and were largely preventable (81%). Of these respiratory outcomes, inadequate ventilation and oxygenation associated with respiratory depressant medications accounted for 37% of the adverse outcomes (hypoventilation = 27.4%; respiratory arrest = 9.5%). In every hypoventilation claim, regardless of the type of anesthetic technique, a failure to optimally monitor the patient's ventilation was identified as a sentinel, contributory practice pattern. Payouts for CRNAs were made in 55% of respiratory claims and averaged $282,840. Claims judged to have an AANA standard-of-practice guideline violation that directly contributed to the adverse outcome were more likely to result in a payout vs those involving no violation (P <.01). Costs to defend against the malpractice allegation for all respiratory event claims averaged $51,996 (SD = $52,658) and ranged from $525 to $227,153.

The Use of Clinical Cervical Spine Clearance in Trauma Patients: A Literature Review.

INTRODUCTION: Five million patients in America are placed in spinal immobilization annually, with only 1% to 2% of these patients suffering from an unstable cervical spine injury. Prehospital agencies are employing selective and limited immobilization practices, but there is concern that this practice misses cervical spine injuries and therefore possibly predisposes patients to worsening injuries. METHODS: A systematic review was conducted that examined literature from the last 5 years that reviewed cervical spine immobilization application and/or clearance in alert trauma patients. RESULTS: Prehospital selective immobilization protocols and bedside clinical clearance examinations are becoming more commonplace, with few missed injuries or poor outcomes. Prehospital providers can evaluate patients in the field safely to assess who needs or does not need cervical collars; similar criteria can be used in the emergency department. Harm from cervical collars is increasingly documented, with concerns that risks exceed possible benefits. DISCUSSION: The literature suggests that alert trauma patients can be cleared from cervical spine immobilization safely through a structured algorithm in either the prehospital or ED setting. The evidence is primarily observational. Thus, many providers who fear missing cervical injuries may be reluctant to follow the recommendations despite few or no published cases of sudden deterioration from missed cervical spine injuries.

Sexual Identity, Adverse Childhood Experiences, and Suicidal Behaviors.

PURPOSE: The objective of this study was to examine the influence of sexual identity and adverse childhood experiences (ACEs) on suicidal behaviors in a population-based sample of high school students. METHODS: A two-stage cluster random sampling design was used to recruit 5,108 students from 97 high schools. A total of 4,955 students (97%) provided information that allowed for classification of sexual identity into three groups: (1) lesbian, gay, or bisexual (LGB) (10%); (2) not sure (4.6%); and (3) heterosexual (85.4%). Five measures of childhood abuse and household dysfunction were summed, and the ACE score was categorized as 0, 1, 2, and 3-5 ACEs. Weighted logistic regression was used to assess the influence of sexual identity, ACEs, and their interaction on suicide ideation and attempts in the past 12 months. RESULTS: Compared with heterosexual students, those who were LGB and were not sure had higher odds of suicide ideation and attempts. There was also a graded relationship between cumulative ACE exposure and suicidal behaviors. Although sexual identity/ACE interaction was not observed, LGB/not sure students who experienced a high number of ACEs were disproportionately affected. Compared with heterosexual students with 0 ACE, LGB/not sure students with 0 ACE (adjusted odds ratio [AOR] = 3.32, 95% confidence interval [CI] = 1.96-5.61), 1 ACE (AOR = 6.58, 95% CI = 4.05-10.71), 2 ACEs (AOR 13.50, 95% CI = 8.45-21.58), and 3-5 ACEs (AOR = 14.04, 95% CI = 8.72, 22.62) had higher odds of suicide ideation. A similar pattern was observed for suicide attempts. CONCLUSIONS: LGB and students not sure of their sexual identity with greater exposure to ACEs have disproportionately high levels of suicide ideation and attempts. Trauma-informed interventions for these populations are warranted.

Childhood Maltreatment and Unprotected Sex among Female Juvenile Offenders: Evidence of Mediation by Substance Abuse and Psychological Distress.

PURPOSE: Research has shown that childhood maltreatment is associated with sexual risk taking among female juvenile offenders; however, the mechanisms by which maltreatment influences sexual risk remain poorly understood. We assessed whether substance abuse, psychological distress, and dating violence mediate the relationship between childhood maltreatment and unprotected sex. METHODS: Sexually active female juvenile offenders (13-17 years of age) completed audio computer-assisted self-interviews (n = 232). Logistic regression with a risk decrement approach, the Sobel test, and the Goodman I test were used to evaluate mediation. RESULTS: Maltreatment before sixth grade was common in our sample, including physical abuse (48.7%), sexual abuse (14.7%), supervision neglect (57.3%), and physical neglect (18.5%). Cumulative childhood maltreatment was also high with 42.2% reporting two or more types. In the fully adjusted model, cumulative childhood maltreatment remained associated with unprotected sex (odds ratio, 2.43; 95% confidence interval, 1.27, 4.65). The percent of the total effect in the relationship between childhood maltreatment and unprotected sex that was mediated by substance abuse was 16.4% (Sobel = 2.54 [p = .01]; Goodman I = 2.49 [p = .01]) and psychological distress accounted for 23.7% (Sobel = 2.55 [p = .01]; Goodman I = 2.51 [p = .01]). Dating violence was not a significant mediator in our analyses. CONCLUSION: We found a strong relationship between childhood maltreatment and unprotected sex among female juvenile offenders that was partially mediated through substance abuse and psychological distress. These findings can be used to develop public health strategies to increase condom use among female juvenile offenders. Trauma-informed approaches to sexual health promotion that address substance abuse and psychological distress are warranted.

Prevalence and Correlates of Any and Frequent Synthetic Cannabinoid Use in a Representative Sample of High School Students.

BACKGROUND: There is increasing evidence that Synthetic Cannabinoid (SC) use is associated with adverse health effects, but little is known about the prevalence of SC use and risk and protective factors for SC use among adolescents. OBJECTIVES: To determine the prevalence and correlates of any and frequent SC use in a representative sample of high school students. METHODS: The 2013 Youth Risk Behavior Survey was administered to 3,928 high school students in Nevada. A state-added question assessed any and frequent SC use (10 or more times). Weighted logistic regression identified factors for both outcomes. RESULTS: 17.3% of students reported SC use and 4.3% used SCs frequently. As expected, there were strong associations between SC use and other substance use. After controlling for substance use, any SC use was associated with being Hispanic (AOR = 1.74; 95% CI = 1.27, 2.38) and living in a rural county (AOR = 1.68; 95% CI = 1.26, 2.23). Frequent SC use was higher among students who were male (AOR = 2.14; 95% CI = 1.19, 3.84), 18 years of age (AOR = 2.34; 95% CI = 1.18, 4.67), lived in a rural county (AOR = 1.84; 95% CI = 1.11, 3.04), and were offered, sold, or given illegal drugs on school property (AOR = 2.40; 95% CI = 1.53, 3.79). Protective factors for frequent SC use included high parental monitoring (AOR = 0.54; 95% CI = 0.31, 0.93) and sports team participation (AOR = 0.61; 95% CI = 0.37, 0.99). CONCLUSIONS/IMPORTANCE: SC prevention policies and programs should focus on adolescents who live in rural settings and engage in substance use. Initiatives to address drug availability as school and promote parent involvement are also warranted.

Digital breast tomosynthesis: studies of the effects of acquisition geometry on contrast-to-noise ratio and observer preference of low-contrast objects in breast phantom images.

The effect of acquisition geometry in digital breast tomosynthesis was evaluated with studies of contrast-to-noise ratios (CNRs) and observer preference. Contrast-detail (CD) test objects in 5 cm thick phantoms with breast-like backgrounds were imaged. Twelve different angular acquisitions (average glandular dose for each ~1.1 mGy) were performed ranging from narrow angle 16° with 17 projection views (16d17p) to wide angle 64d17p. Focal slices of SART-reconstructed images of the CD arrays were selected for CNR computations and the reader preference study. For the latter, pairs of images obtained with different acquisition geometries were randomized and scored by 7 trained readers. The total scores for all images and readings for each acquisition geometry were compared as were the CNRs. In general, readers preferred images acquired with wide angle as opposed to narrow angle geometries. The mean percent preferred was highly correlated with tomosynthesis angle (R = 0.91). The highest scoring geometries were 60d21p (95%), 64d17p (80%), and 48d17p (72%); the lowest scoring were 16d17p (4%), 24d9p (17%) and 24d13p (33%). The measured CNRs for the various acquisitions showed much overlap but were overall highest for wide-angle acquisitions. Finally, the mean reader scores were well correlated with the mean CNRs (R = 0.83).

Morphological characterization of Mycobacterium tuberculosis in a MODS culture for an automatic diagnostics through pattern recognition.

Tuberculosis control efforts are hampered by a mismatch in diagnostic technology: modern optimal diagnostic tests are least available in poor areas where they are needed most. Lack of adequate early diagnostics and MDR detection is a critical problem in control efforts. The Microscopic Observation Drug Susceptibility (MODS) assay uses visual recognition of cording patterns from Mycobacterium tuberculosis (MTB) to diagnose tuberculosis infection and drug susceptibility directly from a sputum sample in 7-10 days with a low cost. An important limitation that laboratories in the developing world face in MODS implementation is the presence of permanent technical staff with expertise in reading MODS. We developed a pattern recognition algorithm to automatically interpret MODS results from digital images. The algorithm using image processing, feature extraction and pattern recognition determined geometrical and illumination features used in an object-model and a photo-model to classify TB-positive images. 765 MODS digital photos were processed. The single-object model identified MTB (96.9% sensitivity and 96.3% specificity) and was able to discriminate non-tuberculous mycobacteria with a high specificity (97.1% M. avium, 99.1% M. chelonae, and 93.8% M. kansasii). The photo model identified TB-positive samples with 99.1% sensitivity and 99.7% specificity. This algorithm is a valuable tool that will enable automatic remote diagnosis using Internet or cellphone telephony. The use of this algorithm and its further implementation in a telediagnostics platform will contribute to both faster TB detection and MDR TB determination leading to an earlier initiation of appropriate treatment.

Community-specific impacts of exotic earthworm invasions on soil carbon dynamics in a sandy temperate forest.

Exotic earthworm introductions can alter above- and belowground properties of temperate forests, but the net impacts on forest soil carbon (C) dynamics are poorly understood. We used a mesocosm experiment to examine the impacts of earthworm species belonging to three different ecological groups (Lumbricus terrestris [anecic], Aporrectodea trapezoides [endogeic], and Eisenia fetida [epigeic]) on C distributions and storage in reconstructed soil profiles from a sandy temperate forest soil by measuring CO2 and dissolved organic carbon (DOC) losses, litter C incorporation into soil, and soil C storage with monospecific and species combinations as treatments. Soil CO2 loss was 30% greater from the Endogeic x Epigeic treatment than from controls (no earthworms) over the first 45 days; CO2 losses from monospecific treatments did not differ from controls. DOC losses were three orders of magnitude lower than CO2 losses, and were similar across earthworm community treatments. Communities with the anecic species accelerated litter C mass loss by 31-39% with differential mass loss of litter types (Acer rubrum > Populus grandidentata > Fagus grandifolia > Quercus rubra > or = Pinus strobus) indicative of leaf litter preference. Burrow system volume, continuity, and size distribution differed across earthworm treatments but did not affect cumulative CO2 or DOC losses. However, burrow system structure controlled vertical C redistribution by mediating the contributions of leaf litter to A-horizon C and N pools, as indicated by strong correlations between (1) subsurface vertical burrows made by anecic species, and accelerated leaf litter mass losses (with the exception of P. strobus); and (2) dense burrow networks in the A-horizon and the C and N properties of these pools. Final soil C storage was slightly lower in earthworm treatments, indicating that increased leaf litter C inputs into soil were more than offset by losses as CO2 and DOC across earthworm community treatments.

Validation of an automated cough detection algorithm for tracking recovery of pulmonary tuberculosis patients.

BACKGROUND: A laboratory-free test for assessing recovery from pulmonary tuberculosis (TB) would be extremely beneficial in regions of the world where laboratory facilities are lacking. Our hypothesis is that analysis of cough sound recordings may provide such a test. In the current paper, we present validation of a cough analysis tool. METHODOLOGY/PRINCIPAL FINDINGS: Cough data was collected from a cohort of TB patients in Lima, Peru and 25.5 hours of recordings were manually annotated by clinical staff. Analysis software was developed and validated by comparison to manual scoring. Because many patients cough in bursts, coughing was characterized in terms of cough epochs. Our software correctly detects 75.5% of cough episodes with a specificity of 99.6% (comparable to past results using the same definition) and a median false positive rate of 4 false positives/hour, due to the noisy, real-world nature of our dataset. We then manually review detected coughs to eliminate false positives, in effect using the algorithm as a pre-screening tool that reduces reviewing time to roughly 5% of the recording length. This cough analysis approach provides a foundation to support larger-scale studies of coughing rates over time for TB patients undergoing treatment.

TsAg5, a Taenia solium cysticercus protein with a marginal trypsin-like activity in the diagnosis of human neurocysticercosis.

Neurocysticercosis is an endemic parasitic disease caused by Taenia solium larva. Although the mechanism of infection is not completely understood, it is likely driven by proteolytic activity that degrades the intestinal wall to facilitate oncosphere penetration and further infection. We analyzed the publicly available T. solium EST/DNA library and identified two contigs comprising a full-length cDNA fragment very similar to Echinococcus granulosus Ag5 protein. The T. solium cDNA sequence included a proteolytic trypsin-like-domain in the C-terminal region, and a thrombospondin type-1 adherence-domain in the N-terminal region. Both the trypsin-like and adherence domains were expressed independently as recombinant proteins in bacterial systems. TsAg5 showed marginal trypsin-like activity and high sequence similarity to Ag5. The purified antigens were tested in a Western immunoblot assay to diagnose human neurocysticercosis. The sensitivity of the trypsin-like-domain was 96.36% in patients infected with extraparenchymal cysts, 75.44% in patients infected with multiple cysts, and 39.62% in patients with a single cyst. Specificity was 76.70%. The thrombospondin type-1 adherence-domain was not specific for neurocysticercosis.

Accuracies of the synthesized monochromatic CT numbers and effective atomic numbers obtained with a rapid kVp switching dual energy CT scanner.

PURPOSE: This study was performed to investigate the accuracies of the synthesized monochromatic images and effective atomic number maps obtained with the new GE Discovery CT750 HD CT scanner. METHODS: A Gammex-RMI model 467 tissue characterization phantom and the CT number linearity section of a Phantom Laboratory Catphan 600 phantom were scanned using the dual energy (DE) feature on the GE CT750 HD scanner. Synthesized monochromatic images at various energies between 40 and 120 keV and effective atomic number (Z(eff)) maps were generated. Regions of interest were placed within these images/maps to measure the average monochromatic CT numbers and average Z(eff) of the materials within these phantoms. The true Z(eff) values were either supplied by the phantom manufacturer or computed using Mayneord's equation. The linear attenuation coefficients for the true CT numbers were computed using the NIST XCOM program with the input of manufacturer supplied elemental compositions and densities. The effects of small variations in the assumed true densities of the materials were also investigated. Finally, the effect of body size on the accuracies of the synthesized monochromatic CT numbers was investigated using a custom lumbar section phantom with and without an external fat-mimicking ring. RESULTS: Other than the Z(eff) of the simulated lung inserts in the tissue characterization phantom, which could not be measured by DECT, the Z(eff) values of all of the other materials in the tissue characterization and Catphan phantoms were accurate to 15%. The accuracies of the synthesized monochromatic CT numbers of the materials in both phantoms varied with energy and material. For the 40-120 keV range, RMS errors between the measured and true CT numbers in the Catphan are 8-25 HU when the true CT numbers were computed using the nominal plastic densities. These RMS errors improve to 3-12 HU for assumed true densities within the nominal density +/- 0.02 g/cc range. The RMS errors between the measured and true CT numbers of the tissue mimicking materials in the tissue characterization phantom over the 40-120 keV range varied from about 6 HU-248 HU and did not improve as dramatically with small changes in assumed true density. CONCLUSIONS: Initial tests indicate that the Z(eff) values computed with DECT on this scanner are reasonably accurate; however, the synthesized monochromatic CT numbers can be very inaccurate, especially for dense tissue mimicking materials at low energies. Furthermore, the synthesized monochromatic CT numbers of materials still depend on the amount of the surrounding tissues especially at low keV, demonstrating that the numbers are not truly monochromatic. Further research is needed to develop DE methods that produce more accurate synthesized monochromatic CT numbers.

Cough detection algorithm for monitoring patient recovery from pulmonary tuberculosis.

In regions of the world where tuberculosis (TB) poses the greatest disease burden, the lack of access to skilled laboratories is a significant problem. A lab-free method for assessing patient recovery during treatment would be of great benefit, particularly for identifying patients who may have drug-resistant tuberculosis. We hypothesize that cough analysis may provide such a test. In this paper we describe algorithm development in support of a pilot study of TB patient coughing. We describe several approaches to event detection and classification, and show preliminary data which suggest that cough count decreases after the start of treatment in drug-responsive patients. Our eventual goal is development of a low-cost ambulatory cough analysis system that will help identify patients with drug-resistant tuberculosis.

A content analysis of cancer survivorship coverage in a representative sample of US news outlets.

BACKGROUND: Media are popular sources of cancer information, yet little is known about how survivors are depicted. METHODS: This study analyzes coverage of cancer survivors in a nationally representative sample of newspapers and television newscasts. Stories were coded for cancer type, gender, age, survivorship length and status, treatment types, and spirituality, among other variables. RESULTS: Media provide limited information about survivors. Also, although breast cancer coverage was close to survivorship rates, nearly every other cancer type was underreported for both incidence and survivorship rates. CONCLUSIONS: Inaccurate media coverage may be contributing to public misunderstanding about cancer survivorship.

Quantitative CT of lung nodules: dependence of calibration on patient body size, anatomic region, and calibration nodule size for single- and dual-energy techniques.

Calcium concentration may be a useful feature for distinguishing benign from malignant lung nodules in computer-aided diagnosis. The calcium concentration can be estimated from the measured CT number of the nodule and a CT number vs calcium concentration calibration line that is derived from CT scans of two or more calcium reference standards. To account for CT number nonuniformity in the reconstruction field, such calibration lines may be obtained at multiple locations within lung regions in an anthropomorphic phantom. The authors performed a study to investigate the effects of patient body size, anatomic region, and calibration nodule size on the derived calibration lines at ten lung region positions using both single energy (SE) and dual energy (DE) CT techniques. Simulated spherical lung nodules of two concentrations (50 and 100 mg/cc CaCO3) were employed. Nodules of three different diameters (4.8, 9.5, and 16 mm) were scanned in a simulated thorax section representing the middle of the chest with large lung regions. The 4.8 and 9.5 mm nodules were also scanned in a section representing the upper chest with smaller lung regions. Fat rings were added to the peripheries of the phantoms to simulate larger patients. Scans were acquired on a GE-VCT scanner at 80, 120, and 140 kVp and were repeated three times for each condition. The average absolute CT number separations between the calibration lines were computed. In addition, under- or overestimates were determined when the calibration lines for one condition (e.g., small patient) were used to estimate the CaCO3 concentrations of nodules for a different condition (e.g., large patient). The authors demonstrated that, in general, DE is a more accurate method for estimating the calcium contents of lung nodules. The DE calibration lines within the lung field were less affected by patient body size, calibration nodule size, and nodule position than the SE calibration lines. Under- or overestimates in CaCO3 concentrations of nodules were also in general smaller in quantity with DE than with SE. However, because the slopes of the calibration lines for DE were about one-half the slopes for SE, the relative improvement in the concentration estimates for DE as compared to SE was about one-half the relative improvement in the separation between the calibration lines. Results in the middle of the chest thorax section with large lungs were nearly completely consistent with the above generalization. On the other hand, results in the upper-chest thorax section with smaller lungs and greater amounts of muscle and bone were mixed. A repeat of the entire study in the upper thorax section yielded similar mixed results. Most of the inconsistencies occurred for the 4.8 mm nodules and may be attributed to errors caused by beam hardening, volume averaging, and insufficient sampling. Targeted, higher resolution reconstructions of the smaller nodules, application of high atomic number filters to the high energy x-ray beam for improved spectral separation, and other future developments in DECT may alleviate these problems and further substantiate the superior accuracy of DECT in quantifying the calcium concentrations of lung nodules.

Long-term and acute effects of zinc contamination of a stream on fish mortality and physiology.

A section of the Upper Enoree River in South Carolina, USA, was contaminated with chemical waste in 1985, and high concentrations of zinc persist decades later. In this study, we examined the zinc concentrations in the water, the accumulation of zinc in a variety of fish tissues, the effects of the contaminated water on fish sperm motility in vitro, and the mortality rates of introduced fish. Zinc concentrations in the water samples collected from six sites decreased as distance from the spill site increased, ranging from 7.3 to 0.34 mg/L (p < 0.001). The zinc concentrations of tissues from native fish were highest in liver (mean across sites of 110 ppm/g tissue) and gills (77.4 ppm/g tissue), followed by gonads (30.7 ppm/g tissue) and muscle (6.9 ppm/g tissue) (p < 0.001). The duration of fast motility of Salmo trutta sperm was significantly diminished in sperm activated in samples from the contaminated stream compared with the control stream (p < 0.05). To further evaluate the ability of fish to survive at the sites with different zinc concentrations, groups of Gambusia holbrooki were placed in traps at a reference site (uncontaminated local tributary), and three sites along the contaminated stream. Rapid mortality was observed in the two sites closest to the spill, including one site in which native fish had been found. The introduced G. holbrooki expressed higher zinc concentration in gills than gonads or muscle (p < 0.001), and water zinc concentration significantly affected fish mortality (p < 0.001). The results from these experiments indicate that zinc contamination of streams can have sublethal effects on populations and physiology of fish that are able to survive in the contaminated water.