Fate of thiamethoxam from treated seeds in mesocosms and response of aquatic invertebrate communities.

Thiamethoxam is a neonicotinoid insecticide widely applied in the Canadian Prairies. It has been detected in surface waters of agro-ecosystems, including wetlands, but the potential effects on non-target invertebrate communities in these wetlands have not been well characterized. In an effort to understand better the fate of thiamethoxam in wetlands and the response of invertebrates (zooplankton and emergent insects), model systems were used to mimic wetland flooding into planted fields. Outdoor mesocosms were treated with a single application of thiamethoxam-treated canola seeds at three treatment levels based on a recommended seeding rate (i.e., 6 kg/ha; 1×, 10×, and 100× seeding rate) and monitored over ten weeks. The mean half-life of thiamethoxam in the water column was 6.2 d. There was no ecologically meaningful impact on zooplankton abundances or community structure among treatments. Statistically significant differences were observed in aquatic insect abundance between control mesocosms and the two greatest thiamethoxam treatments (10× and 100× seeding rate). The observed results indicate exposure to thiamethoxam at environmentally relevant concentrations likely does not represent a significant ecological risk to abundance and community structure of wetland zooplankton and emergent insects.

Surface oil is the primary driver of macroinvertebrate impacts following spills of diluted bitumen in freshwater.

The response of freshwater invertebrates following accidental releases of oil is not well understood. This knowledge gap is more substantial for unconventional oils such as diluted bitumen (dilbit). We evaluated the effects of dilbit on insect emergence and benthic invertebrates by conducting experimental spills in limnocorrals (10-m diameter; ~100-m3) deployed in a boreal lake at the IISD-Experimental Lakes Area, Canada. The study included seven dilbit treatments (spill volumes ranged from 1.5 L [1:66,000, oil:water, v/v] to 180 L [1:590, oil:water, v/v]), two controls, and additional lake reference sites, monitored for 11 weeks. Invertebrate emergence declined at the community level following oil addition in a significantly volume-dependent manner, and by 93-100 % over the 11 weeks following the spill in the highest treatment. Dilbit altered community structure of benthic invertebrates, but not abundance. One-year post-spill and following oil removal using traditional skimming and absorption techniques, benthic richness and abundance were greater among all treatments than the previous year. These results indicate that recovery in community composition is possible following oil removal from a lake ecosystem. Research is needed concerning the mechanisms by which surface oil directly affect adult invertebrates, whether through limiting oviposition, limiting emergence, or both. The response of benthic communities to sediment tar mats is also warranted.

Comparison of the Cosmed K4 b(2) and the Deltatrac II metabolic cart in measuring resting energy expenditure in adults.

BACKGROUND AND AIMS: The objective of the study was to compare data obtained from the Cosmed K4 b(2) and the Deltatrac II metabolic cart for the purpose of determining the validity of the Cosmed K4 b(2) in measuring resting energy expenditure. METHODS: Nine adult subjects (four male, five female) were measured. Resting energy expenditure was measured in consecutive sessions using the Cosmed K4 b(2), the Deltatrac II metabolic cart separately and the Cosmed K4 b(2) and Deltatrac II metabolic cart simultaneously, performed in random order. Resting energy expenditure (REE) data from both devices were then compared with values obtained from predictive equations. RESULTS: Bland and Altman analysis revealed a mean bias for the four variables, REE, respiratory quotient (RQ), V CO(2), V O(2) between data obtained from Cosmed K4 b(2) and Deltatrac II metabolic cart of 268+/-702 kcal/day, -0.0+/-0.2, 26.4+/-118.2 and 51.6+/-126.5 ml/min, respectively. Corresponding limits of agreement for the same four variables were all large. Also, Bland and Altman analysis revealed a larger mean bias between predicted REE and measured REE using Cosmed K4 b(2) data (-194+/-603 kcal/day) than using Deltatrac metabolic cart data (73+/-197 kcal/day). CONCLUSIONS: Variability between the two devices was very high and a degree of measurement error was detected. Data from the Cosmed K4 b(2) provided variable results on comparison with predicted values, thus, would seem an invalid device for measuring adults.

A review of the role of social support systems in the drug use behavior of Hispanics.

In this article the authors conducted a critical review of ongoing and recently completed drug abuse studies which have examined the importance of social support systems in the drug-using behavior of Hispanics. Published and unpublished preliminary data from these studies are presented and discussed. This critical review of the research literature supports earlier findings that social support systems play an important role in preventing drug abuse among Hispanics. Specifically, this review found that familial factors, peer influences, involvement with religious institutions, and after-school activities have a powerful impact on the drug-using behaviors of Hispanic child, youth and adult drug users. The authors suggest that drug prevention and treatment programs within Hispanic communities will be more successful if they incorporate social support systems into their programs. In conclusion, the authors identify areas in which the role of social support systems in the drug-using behavior of Hispanics need further investigation.

Energy expenditure in 100 ventilated, critically ill children: improving the accuracy of predictive equations.

OBJECTIVE: The purpose of this study was to evaluate current methods of predicting energy requirements and to develop and validate new equations derived from energy expenditure measurements of ventilated, critically ill children. DESIGN: Prospective, observational, sequential study. SETTING: Pediatric intensive care unit. PATIENTS: A total of 100 ventilated, critically ill children who fit the criteria of energy expenditure measurement. Additional patients (n = 25) were included in the validation study. INTERVENTION: An indirect calorimeter was used to measure energy expenditure for a period of 30 mins. MEASUREMENTS AND MAIN RESULTS: The mean measured energy expenditure was 185+/-51 kJ/kg per day. Predicted energy expenditure from standard equations was compared with measured energy expenditure by using the Bland and Altman "methods comparison procedure," and poor precision and accuracy were observed. Patient variables were collected at the time of measurement, and multiple regression analysis was performed to determine the independent contribution of each variable to measure energy expenditure. New predictive equations were formulated and validated with additional energy expenditure measurements. Patient variables that did not correlate significantly with energy expenditure were gender, Pediatric Risk of Mortality score, and commencement of nutritional support. An equation was derived from patient variables (age, weight, weight for age Z score, body temperature, number of days after intensive care admission, and primary reason for admission) that correlated significantly (r2 = .898) with measured energy expenditure. A second, simplified equation (energy expenditure kJ/day = ¿17 x age [months]¿ + ¿48 x weight [kg]¿ + ¿292 x body temperature degrees C¿ - 9,677) was produced (r2 = .867). Validation found no significant difference between measured and predicted energy expenditure by the new equations; however, the equations did not predict accurately for patients <2 months of age. CONCLUSION: The new equations provide a more accurate alternative to current predictive methods in assessing energy requirements of ventilated, critically ill children.

Energy expenditure measurements in ventilated critically ill children: within- and between-day variability.

BACKGROUND: Energy expenditure measurement (EEM) by indirect calorimetry is used as a research and clinical tool in pediatric intensive care units. The aims of the study were to determine if a 30-minute EEM is representative of a 24-hour EEM (within-day variation); to determine if there is any diurnal variation during the 24-hour period of EEM; and to determine if there is a clinically significant between day variation of EEMs. METHODS: To determine within-day variation, energy expenditure was measured for a period of 24 hours for each subject (n = 11). The 24-hour period was then divided into 30-minute periods. The 30-minute means were compared with the 24-hour means. To determine between-day variation, EEMs were made daily for 30 minutes. RESULTS: In the within-day study, the overall mean percent coefficient of variation of the 30-minute measurements was 7.2% +/- 4.5%. There was no significant difference between the 30-minute means and the 24-hour means for each patient (p < .691). In 8 subjects the 30-minute means did not differ from the 24-hour mean by more than 20%. No diurnal variation was observed. The mean percent variation of between day EEM was 21% +/- 16%; the range was 1% to 69%. CONCLUSION: In critically ill ventilated children, clinically relevant within-day variations in EEM are uncommon and a single 30-minute EEM gives an acceptable guide to the level of nutrition support required. Between-day variations can, however, be large and daily EEMs are required.

Factors influencing enrollment in clinical trials for cancer treatment.

BACKGROUND: Recruitment of cancer patients to clinical trials is an ongoing challenge. In this study, we assess factors that may influence enrollment in clinical trials for cancer treatment. METHODS: Between June 1997 and January 1998, data were collected on all adult cancer patients evaluated for enrollment in National Cancer Institute-sponsored clinical trials at 15 medical facilities in the southeastern United States. RESULTS: More than 2,300 cancer patients were evaluated; 7% were enrolled. Neither patient sex nor race predicted enrollment. Patients with fee-for-service coverage were more than twice as likely to be enrolled compared with patients with other types of coverage, including managed care. Patient refusal accounted for the nonenrollment of nearly 40% of those clinically eligible. CONCLUSIONS: Although multiple factors influence enrollment in clinical trials for cancer treatment, results suggest that insurance coverage plays a role. Patient refusal, a substantial reason for nonenrollment, points to the need for continued efforts to educate physicians and the public in the value of clinical trials.

Hemispheric specialization in schizophrenics with perceptual aberration.

Higher rates of left-handedness and atypical lateralization in schizophrenics paired with findings of morphological abnormalities in cerebral asymmetry suggest that the normal patterns of hemisphere specialization for processing verbal and spatial information may be anomalous in schizophrenics. The small number of studies that have addressed this question have produced inconsistent findings and varied with subtype diagnosis, gender, type of task employed, task difficulty, and control of handedness. Conflicting research findings also may be due to confounding from the heterogeneity of the schizophrenic construct and variability in clinical symptoms across patients. The present study was designed to control for factors that may have confounded earlier studies. Because the study used perceptual measures, the relationship between symptoms of perceptual aberration and hemisphere advantages was examined using Chapman et al.'s (1978) Perceptual Aberration Scale (PAS). Fifteen male schizophrenic patients and 14 male controls were administered tachistoscopic letter and facial recognition go/no-go reaction time tasks. Left hemisphere advantages were found for both controls and schizophrenics on the letter task. Right hemisphere advantages were found for controls on the facial task but not schizophrenics. Instead, a strong negative correlation was found between schizophrenics' PAS scores and hemisphere advantages (r = -0.685, p < 0.007). Further analysis identified a subgroup of schizophrenics with perceptual aberration who exhibited reversed left hemisphere advantages that increased as the PAS scores increased. Additional research is needed to determine whether this subgroup of schizophrenics constitutes a meaningful subtype with a distinct disease process that disrupts the development of normal cerebral lateralization. The findings provide further evidence for the importance of examining relationships between schizophrenics' performance on cognitive measures and their symptom patterns.

Three-dimensional computed tomography in the assessment of fractures of the acetabulum.

Axial CT has, for many years, been shown to be superior to conventional radiology in the demonstration and assessment of acetabular fractures. The more recent development of complex computer programmes has enabled the production of three-dimensional images (3D CT) from sets of contiguous axial scans. 3D CT permits full imaging of the pelvis with the minimum of distress to the patient and with the minimum of radiation exposure. The ability to rotate the 3D images around a variety of axes provides a valuable perceptual link between conventional radiographs and axial CT, and enables the creation of unique images that offer perspectives unobtainable by conventional radiology. The improved visualization of the pelvis leads to more accurate diagnosis of the fracture, and hence better surgical planning and management.

An assessment of human services program outcome measures: are they credible, feasible, useful?

The authors present the results of an assessment of human service program outcome measures included in a county department's formative evaluation system. The criteria of credibility, feasibility, and utility provided the framework for examining measures in the context of the field environment within which programs operate and are evaluated. Recommendations address findings regarding three categories of evaluation measure and their potential application in other agency settings.

Autism from the inside.

Our hypothesis is that the endogenous opiate system is malfunctioning in autistic people. Levels of endorphins (and perhaps enkephalins) are fluctuating below and above normal levels leading to sensory deprivation. The sensations from all the sense organs are too great when the endorphin (and enkephalin) level is low making them meaningless or too little when the endorphin level is high leading to lack of sensation. Some of the bizarre repetitive behaviours are endorphin producing activities which cut down distressing sensation, others are attempts to cut down excessive stimuli from the environment, while others remain completely baffling. The thalamus could be one of the regions of the brain where inhibitory neurones and opiate receptors are malfunctioning and the feed back system initiated by the hypothalamus could have been damaged by the same agent. In both cases the damage could have been caused by chemical imbalance about the time of birth affecting the normal action of endorphins, enkephalins and prostaglandins. More boys than girls may be autistic because their brains are less mature at birth or because the male and female opiate systems are distinct.

Cytoskeletal changes during adhesion and release: a comparison of human and nonhuman primate platelets.

The organization of cytoskeletal proteins in whole-mount adherent platelets from African green monkeys and normal human volunteers has been studied by SEM, high vacuum electron microscopy (HVEM) and conventional (120 kV) electron microscopy. We describe three distinct organizational zones, the Central Matrix, the Trabecular Zone and the Peripheral Web in spread platelets from both sources. The Central Matrix is an ill-defined superstructure of 80-100 A filaments of short length which enshrouded the granules, dense bodies, mitochondria and elements of the open-channel and dense-tubular systems. The latter, identified through the use of peroxidase cytochemistry with the whole mounts, is an anastomosing network of elongate saccules having diameters of 600-1200 A. The Trabecular Zone, which encircles the Central Matrix, contains 165, 80-100 and 30-50 A filaments in an open lattice of irregular lattice spacing. The outermost region of the cells, the Peripheral Web, is comprised of 70 A filaments organized in a honeycomb lattice with center to center spacing in the range 150-300 A. This pattern for the spread cells is not consistently observed in cells during the early stages of adhesion; therefore, correlations of SEM and TEM observations are made for the various stages of adhesion/activation.

Ego development in adult women.

Ego development in adult women was studied using Loevinger's Sentence Completion Test of Ego Development (SCT). The subjects were 163 women in a university nurse practitioner training program. Ego development scores were correlated with scores from personality tests and with interview data. Higher ego levels were related to personal adjustment, nurturance, responsibility, tolerance, enjoyment of children, inner control, capacity for status, and age. Improvement in ego level scores was found only for those at, or below, the self-aware level. The SCT, as scored for women, seems to be particularly sensitive to differences in responsible caring in relationships, an aspect of personality development often neglected by other tests.

An epidemiological view of poisoning.

An epidemiological approach to understanding the incidence and control of injuries is essential. Epidemiology facilitates discovery of factors contributing to the occurrence of, in this case, injuries from poisoning. This page reviews those theories relative to agent, host and environment involved in an unintentional poisoning incident. It is through an understanding of each of these factors that the poisoning incident becomes more clearly defined.

Concurrent endothelial cell turnover and leukocyte margination in early atherosclerosis.

Leukocyte margination and migration into nascent atherosclerotic lesion have been suggested as two early events in aortic atherosclerosis. It has also been suggested that altered endothelial cell function may mediate the margination process. In this paper we present quantitative data on leukocyte adherence to the luminal aspect of the aortic endothelium and correlate it with severity of atherosclerosis and extent of endothelial cell turnover. Both naturally occurring and cholesterol induced atherosclerotic lesions were studied. The sites of endothelial cell turnover were determined by scanning electron microscope whole mount autoradiography of 3H-thymidine labeled aortas. Morphometric analysis of atherosclerosis severity and leukocyte adhesion was accomplished by stereological analysis of conventional SEM preparations. Leukocyte adherence was localized in atherosclerosis susceptible areas of the aorta and increased dramatically over atherosclerotic lesions. Endothelial cell turnover also increased in atherosclerotic areas as indicated by an increase in the number of labeled nuclei found over lesions. Both leukocyte adherence and endothelial cell turnover occurred over the entire extent of the lesions studied, but were particularly prevalent at the growing edge of the lesions.

Three-dimensional organization of the platelet cytoskeleton during adhesion in vitro: observations on human and nonhuman primate cells.

Adhesion of platelets in vitro resulted in rapid polymerization of the amorphous cytoplasmic ground substance into an organized cytoskeletal superstructure. This cytoskeleton, characterized through the use of whole-mount and stereo (3-D), high-voltage microscopy in conjunction with morphometrics and cytochemistry, comprised four major size classes of filaments organized in distinctive zones. The central matrix, or granulomere, at the center of the cell mass, was an ill-defined meshwork of 80-100-A filaments which enshrouded granules, dense bodies, and elements of the dense tubular system as identified through peroxidase cytochemistry. Demarcating this central matrix was a trabecular zone containing 30-50, 80-100, and 150-170 A filaments in an open and rigid-appearing lattice. Circumscribing the trabecular zone and extending to the margins of the hyalomere was the third region, the peripheral web, in which 70-A filaments were arranged in a tight honeycomb lattice. This organizational pattern was retained in cytoskeletons prepared by Triton x-100 extraction of the adherent cells, and was observed in basally located cells of aggregates which formed subsequent to adhesion. Our observations are consistent with biochemical studies of cytoskeletons prepared from suspended platelets and suggest a contractile protein composition for the superstructure during adhesion.