Zinc and cadmium body burdens in terrestrial oligochaetes: use and significance in environmental risk assessment

Uptake and elimination kinetics of zinc and cadmium were studied in the oligochaetes Enchytraeus albidus and Eisenia fetida. Even at the highest exposure concentrations where E. fetida survived, the internal zinc concentration was still regulated to a constant level. Enchytraeus albidus could not regulate the internal zinc concentration as well, and the body burden increased after exposure to high zinc concentrations. After transfer to clean soil, the internal zinc concentration dropped back to the control level within a few weeks. For both species, internal cadmium concentrations did not reach equilibrium during the uptake experiments. The internal concentrations causing 50% reduction in cocoon production for E. fetida exposed to cadmium varied between different soil types, indicating that no fixed critical body burdens exist. For both zinc and cadmium, bioaccumulation factors decreased with increasing soil metal concentrations. Bioaccumulation factors may therefore be poor indicators of environmental risk. Their dependence on the total soil concentration makes bioaccumulation factors also unsuitable for assessing the influence of soil characteristics on the bioavailability of metals in contaminated field soils. For the same reason, uptake rate constants are probably not suited for this purpose.

Effect of clay and organic matter type on the ecotoxicity of zinc and cadmium to the potworm Enchytraeus albidus

Clay and organic matter are considered as important parameters influencing bioavailability and ecotoxicity of metals in soils. As there exists a large variation in the type of clay and organic matter in field soils, the quantity of these variables alone may not be good indicators of metal bioavailability. To test this hypothesis, toxicity experiments with the potworm Enchytraeus albidus were conducted in artificial soils with three types of clay and seven types of organic matter, while the soil pH was kept constant. The 14d LC50 of zinc and cadmium varied from 83.0 to 1,140 mg Zn/kg D.W. and from 55.2 to 704 mg Cd/kg D.W., respectively, depending on the type of clay and organic matter that were used. Simultaneous measurements of the cation exchange capacity showed that this soil parameter is a better indicator of the bioavailability as it takes into account the type of clay and organic matter as well as other adsorption phases such as metal oxyhydroxides.

Modeling zinc toxicity for terrestrial invertebrates

Acute and chronic ecotoxicity tests with zinc were performed with the earthworm Eisenia fetida, the potworm Enchytraeus albidus, and the springtail Folsomia candida. To assess the influence of the soil type on zinc toxicity for these soil invertebrates, these tests were carried out in a standard artificial soil, a sandy and a loamy field soil. Based on the results of this experimental work and data taken from literature, models were developed relating the ecotoxicity of zinc to the most important parameters controlling bioavailability: pH and cation exchange capacity. Models were developed for E. fetida and F. candida using the regression technique partial least squares projection to latent structures (PLS). Acute as well as chronic toxicity data of both organisms could be normalized on the basis of the pH and the cation exchange capacity of the test soils. For other terrestrial invertebrates, not enough data were available to develop reliable models.

Test designs to assess the influence of soil characteristics on the toxicity of copper and lead to the oligochaete Enchytraeus albidus

Statistical test designs were used to identify and quantify the soil parameters important for determining the ecotoxicological effects of copper and lead to the potworm Enchytraeus albidus. The application of a Fractional Factorial Design revealed that the acute toxicity of copper and lead to E. albidus can vary over more than two orders of magnitude depending on the physico-chemical characteristics of the (artificial) soils. The differences in metal ecotoxicity were mainly determined by pH and organic matter content or cation exchange capacity (CEC). Using a Central Composite Design, models were developed describing the ecotoxicity of copper and lead to E. albidus as a function of these parameters. To validate the developed response surface models, two field soils and the standard artificial soil prescribed by OECD were spiked with copper and lead and the acute toxicity to E. albidus was assessed. These validation experiments confirmed that the toxicity of copper and lead could be predicted using information on the total metal concentration, the pH and the CEC of the soil with toxicity decreasing with increasing pH and CEC.

Manipulation of total knee replacements. Is the flexion gained retained?

As part of a prospective study of 476 total knee replacements (TKR), we evaluated the use of manipulation under anaesthesia in 47 knees. Manipulation was considered when intensive physiotherapy failed to increase flexion to more than 80 degrees. The mean time from arthroplasty to manipulation was 11.3 weeks (median 9, range 2 to 41). The mean active flexion before manipulation was 62 degrees (35 to 80). One year later the mean gain was 33 degrees (Wilcoxon signed-rank test, range -5 to 70, 95% CI 28.5 to 38.5). Definite sustained gains in flexion were achieved even when manipulation was performed four or more months after arthroplasty (paired t-test, p < 0.01, CI 8.4 to 31.4). A further 21 patients who met our criteria for manipulation declined the procedure. Despite continued physiotherapy, there was no significant increase in flexion in their knees. Six weeks to one year after TKR, the mean change was 3.1 degrees (paired t-test, p = 0.23, CI -8.1 to +2).

Manipulation of total knee replacements

As part of a prospective study of 476 total knee replacements (TKR), we evaluated the use of manipulation under anaesthesia in 47 knees. Manipulation was considered when intensive physiotherapy failed to increase flexion to more than 80°. The mean time from arthroplasty to manipulation was 11.3 weeks (median 9, range 2 to 41). The mean active flexion before manipulation was 62° (35 to 80). One year later the mean gain was 33° (Wilcoxon signed-rank test, range −5 to 70, 95% CI 28.5 to 38.5). Definite sustained gains in flexion were achieved even when manipulation was performed four or more months after arthroplasty (paired t-test, p < 0.01, CI 8.4 to 31.4).

A further 21 patients who met our criteria for manipulation declined the procedure. Despite continued physiotherapy, there was no significant increase in flexion in their knees. Six weeks to one year after TKR, the mean change was 3.1° (paired t-test, p = 0.23, CI −8.1 to +2).

Submuscular versus subcutaneous pectoral implantation of cardioverter-defibrillators: effect on high voltage pathway impedance and defibrillation efficacy

Implantable cardioverter-defibrillator (ICD) pulse generators are now routinely positioned in a pectoral location, either submuscularly (under the pectoralis muscles) or subcutaneously (over the pectoralis muscles). Furthermore, in current ICDs, the generator shield usually participates in the defibrillation energy pathway ("hot can"). Consequently, the precise generator location could affect defibrillation system efficacy. To assess this issue, we compared high voltage pathway impedance and defibrillation threshold (DFT) in 20 patients undergoing submuscular and 46 patients undergoing subcutaneous pectoral implantation of an Angeion Sentinel ICD and an AngeFlex dual-coil defibrillation lead. Measurements were performed at time of ICD implant, pre-hospital discharge, and 1, 3 and/or 6 months later. Following induction of ventricular fibrillation, 569 biphasic waveform shocks were delivered between the generator shield and either the distal defibrillation coil (RV/can configuration) or both proximal and distal coils (RV/SVC/can configuration). Impedance differences between submuscular and subcutaneous implants were approximately 3-4 Ohms (p value of 0.132 to < 0.001 depending on time of follow-up and lead configuration). A significant increase in impedance over time was noted independent of implant location and lead configuration. The DFT at implant or pre-discharge was assessed in 27 individuals, and was 9.9 +/- 3.8 J in 8 patients in the submuscular group, and 7.4 +/- 3.3 J in 19 patients in the subcutaneous group (p = 0.057). In conclusion, anatomic location of a "hot can" ICD generator (submuscular versus subcutaneous) influences impedance to defibrillation current, but the impact is of small magnitude and does not appear to result in clinically important differences in DFT.

Primary health care. Using computers to enhance care in a GP practice

This paper describes the use of a computer database to assist communication between district nurses and GPs. The database details nursing care and forms an essential two-way communication tool that not only improves patient care but also strengthens teamwork.

Transmission of Creutzfeldt-Jakob disease to the patas monkey (Erythrocebus patas) with cytopathological changes in in vitro cultivated brain cells

The transmission of Creutzfeldt-Jakob disease (CJD) to the patas monkey, Erythrocebus patas, has been accomplished. Clinical neurological disease was first noticed 47 months and 23 days after intracerebral inoculation of infected squirrel monkey brain. The disease progressed slowly and lasted 8 months. Microscopic examination of the brain and spinal cord revealed lesions of status spongiosus and astrogliosis in the cortical gray matter consistent with a diagnosis of experimental CJD. A vacuolating 'spongiform' cytopathological effect was seen in many of the in vitro cultivated brain cells in the outgrowth from explanted brain tissue of this monkey.