In situ water and sediment toxicity in an agricultural watershed

The Salinas River receives inputs from extensive farmlands before flowing into the Salinas River National Wildlife Refuge and the Monterey Bay National Marine Sanctuary (CA, USA). Previous monitoring using laboratory toxicity tests and chemical analyses identified toxic agricultural drain-water inputs in this system. Using caged daphnids (Ceriodaphnia dubia) and amphipods (Hyalella azteca), we investigated in situ toxicity at stations downstream from an agricultural drain relative to a reference station. A flow sensor indicated highly variable inputs from irrigation, and daily synoptic chemical analyses using enzyme-linked immunosorbent assay techniques demonstrated fluctuating concentrations of organophosphate pesticides. Test organism mortality in the field coincided with contaminant concentrations that exceeded chemical effect thresholds for the test species. Laboratory toxicity tests using C. dubia were comparable to results from field exposures, but tests with H. azteca were not. Laboratory exposures can be reasonable surrogates for field evaluations in this system, but they were less effective for assessing short-term temporal variability. Results from the field toxicity studies corroborated results of bioassessment surveys conducted as part of a concurrent study. Toxicity identification evaluations indicated that organophosphate pesticides caused toxicity to daphnids and that effects of suspended solids were negligible.     

Zebras on the commons: rare conditions in family practice

BACKGROUND: Family physicians (FPs) specialize in the management of common problems, but we know little about their role in the care of patients with rare conditions. Objective: To describe the roles FPs play in the identification and management of patients with rare conditions in a typical practice. METHODS: Office record review of 100 patients with rare conditions in the everyday, community-based, private practice of 4 FPs. Analysis of patient demographic characteristics, diagnoses, and the roles played by the FP in the patient's care, including diagnosis, treatment, referral, and long-term patient management. RESULTS: These FPs cared for patients with a wide variety of rare disorders across the spectrum of patient age and sex, organ system involved, and medical specialty area. FPs identified the problem in 89%, diagnosed the disorder in 54%, provided acute care in 56%, and provided continuing care for 76% of patients. FPs consulted other physicians in 85% of cases. The condition was life threatening in 58% of patients. CONCLUSIONS: Family physicians provide a broad range of services to a wide variety of patients with rare medical problems.     

General anaesthesia or conscious sedation for painful procedures in childhood cancer: the family's perspective

Background: Until recently, midazolam sedation was routinely used in our institution for bone marrow aspirates and lumbar punctures in children with cancer. It has been perceived by many doctors and nurses as being well tolerated by children and their families. Aim: To compare the efficacy of inhalational general anaesthesia and midazolam sedation for these procedures. Methods: A total of 96 children with neoplastic disorders, who received either inhalational general anaesthesia with sevoflurane, nitrous oxide, and oxygen (GA) or sedation with oral or nasal midazolam (SED) as part of their routine preparation for procedures were studied. The experiences of these childen were examined during their current procedure and during their first ever procedure. Main outcome measures were the degree of physical restraint used on the child, and the levels of distress and pain experienced by the child during the current procedure and during the first procedure. The family‘s preference for future procedures was also determined. Results: During 102 procedures under GA, restraint was needed on four occasions (4%) when the anaesthetic mask was first applied, minimal pain was reported, and children were reported as distressed about 25% of the time. During 80 SED procedures, restraint was required in 94%, firm restraint was required in 66%, the child could not be restrained in 14%, median pain score was 6 (scale 0 (no pain) to 6 (maximum pain)), and 90% of the parents reported distress in their child. Ninety per cent of families wanted GA for future procedures. Many families reported dissatisfaction with the sedation regime and raised concerns about the restraint used on their child. Conclusions: This general anaesthetic regime minimised the need for restraint and was associated with low levels of pain and distress. The sedation regime, by contrast, was much less effective. There was a significant disparity between the perceptions of health professionals and those of families with respect to how children coped with painful procedures.     

Glycine conjugation of para-aminobenzoic acid (PABA): a pilot study of a novel prognostic test in acute liver failure in children

BACKGROUND: Fulminant hepatic failure (FHF) is associated with high mortality; few patients survive without liver transplantation. It is important to have a sensitive, specific early predictor of outcome to distinguish potential survivors (S) from nonsurvivors (NS). OBJECTIVE: Because we had previously shown that glycine conjugation of para-aminobenzoic acid (PABA) quantitatively reflects liver function in children with chronic liver disease, in this pilot study we wanted to determine whether the measurement of the glycine conjugates of PABA could distinguish S from NS in FHF in comparison with standard prognostic indices. METHODS: Twenty-four patients were studied: acute severe hepatitis (n = 7), subfulminant hepatic failure (n = 7), and FHF (n = 10). Assessment of King's College criteria, measurement of factor V and VII levels, PABA testing, and transjugular liver biopsies were performed in almost all patients within 48 hours of admission. Serum PABA and its glycine conjugates (para-aminohippurate (PAHA) and para-acetamidohippurate (PAAHA)) were measured thirty minutes after oral administration by high-pressure liquid chromatography. Poor prognostic categories as previously established in the literature were defined as factor V < 0.20U/ml, factor VII < 0.08 U/ml, % necrosis >70%, hippurate ratio = 0%, and PAHA = 0M. RESULTS: The measurement of PAHA was the best predictor of a poor outcome in patients with acute liver failure with a sensitivity of 92%, and negative predictive value (NPV) of 92% compared with a sensitivity of 54% and a NPV of 63% with King's College criteria. CONCLUSION: Measurement of serum PAHA is the best early prognostic marker of death in children who suffer from FHF.     

How is the fusiform gyrus related to category-specificity?

There is growing evidence from functional imaging studies that distinct regions in the fusiform gyri are differentially sensitive to object category. In this paper, we investigate how the areas that are more sensitive to animals than tools respond to other visual and semantic variables. We illustrate that (1) category effects in the fusiform areas are stronger for pictures of objects than their written names; (2) retrieving information on the colour or size of objects activates a left lateralised fusiform area that lies anterior to the category-sensitive areas; and (3) both left and right category-sensitive areas respond strongly to visual feature detection on false fonts-meaningless visual stimuli with no semantic associations. These results dissociate the responses in two fusiform areas: The posterior category-sensitive areas are primarily modulated by visual input, whereas a more anterior polymodal region is involved in the retrieval of visual information. In addition, we demonstrate that the posterior areas which are more active for animals than tools are also more active for fruits than tools. Our data are therefore consistent with the proposal that activation in the lateral posterior fusiform gyri reflects the demands on structural differentiation. Since animals and fruits tend to have more structurally similar neighbours than man-made kinds of objects, category effects are likely to be observed during most picture identification tasks. In contrast, when the stimuli are written or auditory names, category effects may only be observed when the task requires access to fine spatial details in the objects' structures.     

Random and systematic beam modulator errors in dynamic intensity modulated radiotherapy

This paper reports on the dosimetric effects of random and systematic modulator errors in delivery of dynamic intensity modulated beams. A sliding-widow type delivery that utilizes a combination of multileaf collimators (MLCs) and backup diaphragms was examined. Gaussian functions with standard deviations ranging from 0.5 to 1.5 mm were used to simulate random positioning errors. A clinical example involving a clival meningioma was chosen with optic chiasm and brain stem as limiting critical structures in the vicinity of the tumour. Dose calculations for different modulator fluctuations were performed, and a quantitative analysis was carried out based on cumulative and differential dose volume histograms for the gross target volume and surrounding critical structures. The study indicated that random modulator errors have a strong tendency to reduce minimum target dose and homogeneity. Furthermore, it was shown that random perturbation of both MLCs and backup diaphragms in the order of sigma = 1 mm can lead to 5% errors in prescribed dose. In comparison, when MLCs or backup diaphragms alone was perturbed, the system was more robust and modulator errors of at least sigma = 1.5 mm were required to cause dose discrepancies greater than 5%. For systematic perturbation, even errors in the order of +/- 0.5 mm were shown to result in significant dosimetric deviations.