A local-scale in situ approach for stressor identification of biologically impaired aquatic systems.

We propose a formal causal evaluation inference process that uses a local-scale in situ approach and provides statistically defensible correlative conclusions for the biological impairment in 303(d)-listed water bodies. Fish assemblage, water chemistry, and aquatic habitat data from 66 locations in the Limberlost watershed, Indiana, were collected in August 2003 to evaluate the condition of the watershed. Anthropogenic stressors were identified from a numerical classification analysis of fish assemblage data using a biological integrity response gradient. Physical and chemical stressors were evaluated relative to the biological integrity response gradient using the Kruskal Wallis analysis of variance by ranks test. Three water chemistry variables (sodium, chloride, and barium) were associated with biological integrity. The percent run habitat, channel morphology score, and Qualitative Habitat Evaluation Index score varied with the degree of dredging. We observed a negative response between the number of species and the biological integrity gradient and a positive response with the percent tolerant individuals. This local-scale in situ approach to physical and chemical data analysis, combined with concurrent biological data collection, provided correlative relations to the impaired condition with localized environmental stressors.

Pediatric iron poisonings in the United States.

BACKGROUND: Iron overdose is considered a leading cause of poisoning-related injury and death in young children. This report analyzes the nature, trend, and hazard patterns of unintentional pediatric iron overdoses in the United States from 1980 to 1996. METHODS: Analyses include multiple regression and correlation analysis of national data on pediatric iron ingestion-related injuries and deaths and review of in-depth investigation case reports. Data sources include files of the US Consumer Product Safety Commission, National Center for Health Statistics, American Association of Poison Control Centers, and US Census Bureau. RESULTS: Pediatric iron-related injuries increased 150% in 1986, from an annual average of 1,200 from 1980 through 1985 to 3,000 from 1986 through 1996. No such annual trend occurred before or after 1986. About one third of the injuries from 1980 through 1996 involved infants under 2 years old, a third involved 2-year-olds, and a third involved children 3 or 4 years old. Pediatric iron-related fatalities increased in 1986, peaked at 10 in 1991, and declined to 2 by 1995. The children often obtained the iron from a child-resistant container opened by themselves or another child or left open or improperly closed by an adult. CONCLUSIONS: Iron overdose remains a significant public health threat to young children. The frequency of pediatric iron overdose injuries increased in 1986 and has not declined. Unit-dose packaging of potent iron supplements is expected to reduce the frequency of severe pediatric iron overdose incidents.

Radiocaesium variability within sheep flocks: relationships between the 137Cs activity concentrations of individual ewes within a flock and between ewes and their progeny.

As a consequence of radiocaesium deposition following the Chernobyl accident the movement and slaughter of sheep were restricted within some upland areas of the United Kingdom. Considerable variability in the radiocaesium activity concentrations between individual sheep within flocks has been recorded. This paper reports studies conducted to investigate the reasons for this within flock variability on three farms in the restricted area of west Cumbria. On each farm, study sheep were selected and live-monitored over the period 1991-93. Results from all three study farms showed a correlation in the 137Cs activity concentration of individual sheep on different monitoring occasions. This observation suggested that a few sheep on each farm are likely to be responsible for the continuation of restrictions on many of the affected holdings. Comparisons between monitoring data obtained in summer and autumn months were better correlated than those involving data collected in the winter and spring. Prior to weaning there was a linear relationship between the 137Cs levels in the muscle of a lamb and that in the muscle of its dam. Given these observations it is suggested that, in successive years, ewes identified as consistently having high radiocaesium levels in their muscle will produce lambs which will also have comparatively high levels of radiocaesium; the limited data available support this hypothesis. However, no relationship between the 137Cs activity concentration of a ewe and its lamb was evident post-weaning, thereby discounting any possibility of an inherited effect. On one of the farms a significant difference was found between the 137Cs activity concentration of different breeds of sheep.

Identification of Ehrlichia chaffeensis morulae in cerebrospinal fluid mononuclear cells.

We report a case of ehrlichiosis in a 72-year-old man who developed extreme lethargy, acute renal failure requiring hemodialysis, and respiratory insufficiency requiring intubation. Lumbar puncture performed on the second day of hospitalization revealed significant cellular pleocytosis. Ehrlichia morulae were tentatively identified in mononuclear cells in routinely processed Wright-stained cytospin preparations of cerebrospinal fluid (CSF). Identification was confirmed by a specific immunocytochemical staining procedure. Subsequent identification specifically as Ehrlichia chaffeensis morulae was established by polymerase chain reaction analysis, which revealed E. chaffeensis-specific DNA in CSF, bone marrow, and blood samples; by indirect fluorescent-antibody analysis, the patient developed an antibody titer of 32,768 against E. chaffeensis antigen. The patient responded to intravenous therapy with doxycycline and dexamethasone. Subsequently, neurologic, hematologic, renal, and pulmonary status had returned to baseline at follow-up 12 weeks after admission. To our knowledge, this is the first identification of E. chaffeensis morulae in CSF cells in an infected patient.

Blood flow and blood volume in a transplanted rat fibrosarcoma: comparison with various normal tissues.

Blood flow measurements following i.v. infusion of iodo-antipyrine labelled with 14C(14C-IAP) and blood volume measurements following i.v. injection of 125I human serum albumin and 51Cr-labelled red blood cells were made in a transplanted rat fibrosarcoma for comparison with various normal tissues. The tumour-blood partition co-efficient for 14C-IAP was found to be 0.79 +/- 0.07 which is similar to most of the normal tissues studied. The solubility of 14C-IAP in plasma was found to be higher than that in whole blood. Blood flow to tumours less than 1000 mm3 was found to be 17.9 +/- 4.0 ml blood 100 g tissue-1.min-1. These values were considered to be primarily measurements of nutritive flow. Blood in the tumours was found to occupy around 1% of the tissue space which was similar to that found for normal muscle and skin. There was no direct correlation between % blood volume and blood flow for the different tissues studied. The haematocrit of blood contained in tumour tissue was calculated to be significantly lower than that of blood contained in the normal tissues. It was suspected that permeability of tumour blood vessel walls to 125I-HSA could have accounted for this difference.

Visualization of the Transparent, Gelatinous House of the Pelagic Tunicate Oikopleura vanhoeffeni Using Sepia Ink.

Appendicularian tunicates of the genus Oikopleura feed using an external, acellular, transparent structure known as the house. Previously, dilute particulate dyes have been used to visualize the internal structure of this house. However, because of toxicity, large particle size, and flocculation, many of these dyes have been of limited practical and scientific use. We report on a new marker, the ink from the cephalopod Sepia officinalis, that solves many of these problems. Specimens of Oikopleura vanhoeffeni relished Sepia ink, having dark black stomachs and producing many dark fecal pellets over several days. When O. vanhoeffeni expanded houses in dilute ink, the internal walls, septae, and filters were shown in great detail, whereas high concentrations of ink showed delicate patterns of lines on the internal walls. We present documentary photographs of previously unillustrated or undescribed morphologies: the escape slot; the incurrent funnels; two dimples caused by insertion of suspensory filaments on the upper wall of the posterior chamber, a large, posterior keel; both the open and closed positions of the exit valve; and the complex pattern of lines on the inner walls. However, the external walls of the house had no affinity for the dye and could only be seen by dark field illumination. We believe that Sepia ink can be used to visualize functionally important transparent structures of other gelatinous zooplankton and can be a colloidal marker in feeding experiments of a wide range of filter feeders.

Experimental studies of thermotolerance in vivo. I. The baby rat tail model.

A detailed study of the kinetics and magnitude of thermotolerance has been made using the endpoint of loss of vertebrae in the baby rat tail. A range of different priming treatments was used and for analysis each priming treatment (PT) was given in terms of the heat sensitivity of the tissue as defined by the single treatment (Ds) required for a given effect, i.e. fractional priming treatment PT/Ds. A considerable degree of thermotolerance could be induced so that at maximum the tissue sensitivity was reduced by a factor of more than four in heating time to produce a given effect, or by more than the equivalent of 2 degrees C. The main results of the study were: (a) that the time to reach maximum thermotolerance depends primarily on PT/Ds, independent of the particular conditions used in the priming treatment; (b) that the extent of the maximum also depends primarily on PT/Ds, but the precise form of the relationship depends on the method used to define thermotolerance; and (c) that the rate of decay of thermotolerance is independent of the priming treatment. The implications of these results for clinical hyperthermia are briefly discussed.

The relationship between heating time and temperature for rat tail necrosis with and without occlusion of the blood supply.

The relationship between time of heating and temperature has been investigated for necrosis resulting in the loss of distal vertebrae in the rat tail. The study was made in both normal conditions and with the blood supply to the tail occluded. In normal conditions there was a transition in the isoeffect relationship close to 42.5 degrees C. Above this temperature a 1 degree C change was equivalent to a change in heating time by a factor of 1.95 +/- 0.01; below 42.5 degrees C the factor increased to 8.1 +/- 0.3. When the tail blood supply was occluded by a clamp the factor was 1.86 +/- 0.01 at temperatures above 42 degrees C and the tissue was considerably more sensitive to hyperthermia. The factor decreased to 1.3 +/- 0.01 at lower temperatures so that the difference in sensitivity between normal and clamped tissue markedly increased with increasing heating time. The results are interpreted in terms of decreased pH resulting from occlusion of the blood supply which renders the tissue more sensitive. The transition in the isoeffect relationship for normal tails is thought to result from the induction of thermal tolerance and is eliminated when the blood supply is occluded. The result is clearly relevant to the heat treatment of regions of tumours with poor blood supply.

The response of mouse skin to hyperthermia combined with fast neutrons or X-rays.

The effects of hyperthermia combined with fast neutrons (mean energy approximately 7.5 MeV) or X-rays (250 kVp) were studied in the skin of the mouse ear and foot. Hyperthermia was achieved by immersion in water at temperatures of 41.5-43.0 degrees C for 1 hour. The heat treatments used caused no observable tissue injury other than transient erythema but they enhanced the response to both neutrons and X-rays. The enhancement of neutron damage increased as the heating temperature was increased, as is well known for X-rays. When heat was given after irradiation the thermal enhancement ratio (t.e.r.) for neutrons was similar to that for X-rays. When heat was given before irradiation the neutron t.e.r. was less than that for X-rays. Consequently, the relative biological effectiveness of fast neutrons compared with X-rays was not altered by giving heat after irradiation but it was reduced by giving heat before irradiation.

The relationship between heating time and temperature: its relevance to clinical hyperthermia.

It is well known that for a given level of damage to either cells in vitro or tissues in situ the relationship between temperature and time of application undergoes a transition in the range 42-43 degrees C and that above this temperature a change of 1 degree C is equivalent to a change in heating time by a factor of two. The present study has concentrated on establishing the relationship between time and temperature over a wide range. The investigation is in two parts, i.e. a review of the literature and an experimental study in which the endpoint used was necrosis in the tail of the baby rat. The aim is to provide information which might help solve a major clinical problem, namely the lack of a satisfactory means of relating treatments given with different temperatures for different lengths of time. The difficulty arises because there is no satisfactory definition of heat dose, in this context. The results confirm the relationship given above for temperatures above the transition. However, below the transition a change of 1 degree C is equivalent to a change in heating time by a factor of six. It is suggested that these relationships provide a means of monitoring a treatment in which the temperature does not remain constant and may vary within a heated volume. The method may also be used to compare treatments from different centres. An indication of the considerable uncertainties of the procedure is given.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of hyperthermia on the oxygen enhancement ratio for x-rays, measured in vivo.

The skin of mouse tail has been used to study the effect of hyperthermia on the oxygen enhancement ratio (OER). Heating was by immersion of a portion of the tail in hot water. Radiation was given either immediately before or after hyperthermia. The average skin reaction between 15 and 50 days after treatment was taken as the end-point. The OER in the absence of hyperthermia was 1.77, suggesting significant hypoxia of the skin. When hyperthermia was given after irradiation the measured value for the OER was not significantly different, but with prior hyperthermia the OER was increased to an average value of 2.3. This increase in OER is probably due to a transient increase in blood circulation following hyperthermia and causing improved tissue oxygenation during irradiation. As a consequence we would expect a greater thermal enhancement ratio for heat given before irradiation than afterwards, and this has frequently been observed with other normal tissues. There was no evidence that heat reduces OER, as has been reported by some authors on the basis of experiments performed on cells in vitro.

The response of the rat tail to hyperthermia.

When the cartilage of the tail of a baby rat is exposed to temperatures between 41 degrees C and 46 degrees C either necrosis or a small degree of stunting in growth may occur. Isoeffect curves relating time and temperature for both these endpoints for normal and clamped tissue were found to be parallel, a doubling of heating time or an increase in temperature of 1 degree C having the same effect in all cases. Clamping sensitizes the tails by a factor of about three in heating time, equivalent to a temperature difference of 1.5 degrees C. Arrhenius plots show an inactivation energy of 140 kcal/mole. This is similar to that found by other workers using different endpoints, and supports the suggestion that protein denaturation is a critical target for direct heat damage.