In a psychiatric census of a 196-bed acute inpatient Medicine for the Elderly unit, 76.1% of patients resident during 1 week were screened and interviewed in a two-stage diagnostic procedure. Of 153 patients studied, 11.1% were delirious, 26.8% were demented, and 9.2% were depressed. Overall, 56.9% of the cases were identified by ward nurses, and 55.5% by the ward doctors; taken together, ward staff identified 75.0% of the cases (kappa = 0.46), indicating that detection of psychiatric disorder in this population might be improved if doctors and nurses pooled their observations on this aspect of patient assessment.

Differential resistance to metal pollution in Daphnia longispina populations was reported in previous studies. In this work, we tried to determine if variation in polymorphic enzymes, often referred as being under metal selection, were related with differences in resistance to acute single- and mixed-metal exposure. Allozyme genotype of 20 putatively polymorphic enzymes, 48-h median lethal concentration (LC50) for copper, and median lethal time (LT50) for a 3% dilution of acid mine drainage (AMD) were determined for 24 lineages of D. longispina. The copper LC50s ranged from 29.3 to 226 microg/L, and the AMD LT50s ranged from 48 min to 25 h and 29 min, with a strong correlation between both end points. Five distinct multilocus genotypes were identified based on polymorphisms in glucose-6-phosphate isomerase, lactate dehydrogenase, malate dehydrogenase, nicotinamide adenine dinucleotide phosphate (NADP+), phosphoglucomutase, and peroxidase. No differences were found in average genotype sensitivity for both toxicity end points or in genotype frequencies between the resistant- and sensitive-lineage groups. The results obtained indicate that allozyme genotype is not associated with increased resistance to acute metal stress in D. longispina.

Plutonium / Galacturonic acid / EPS / Complexation / BindingSummary. The conditional stability constants for trace-level concentrations of Pu(IV) complexing with galacturonic acid and EPS, isolated from axenic Clostridium sp., P. fluorescens and Shewanella putrefaciens CN32 cultures, were determined at pH 4 and an ionic strength of 0.1 M NaCl using an ionexchange technique. The analysis of ion-exchange data with Schubert's technique indicates that the Pu binding by galacturonic acid and EPS from Clostridium sp. and S. putrefaciens can be described based on the formation of 1 : 1 Pu(IV)-ligand complexes. However, the accurate description of Pu binding by EPS from P. fluorescens requires postulation of a mixture of 1 : 1/1 : 2 complexes between Pu(IV) and ligands under the experimental conditions studied.The results from the ion-exchange experiments were also modeled based on a non-electrostatic, discrete ligand approach in which bacterial EPS is conceptualized as being composed of a suite of monoprotic acids, HL i , of arbitrarily-assigned pK a (i) values (e.g., 4, 6 and 8). The examination of ionexchange data in a chemical model suggested that only the pK a 4 (L 1 ) and 6 (L 2 ) ligands are sufficient to accurately simulate the Pu(IV)/EPS binding, implying that carboxylic groups in EPS are the primary binding sites for complexing with Pu(IV) under the experimental conditions examined. The affinity of EPS for complexing Pu(IV) decreases in the order of Clostridium sp. > S. putrefaciens > P. fluorescens although the concentrations of carboxylic groups in EPS decrease in the order of P. fluorescens > S. putrefaciens > Clostridium sp. This discrepancy may be due to differences in binding affinities between Na + ion in solution and EPS ligands. At I = 0.1 M, models demonstrated that the EPS from P. fluorescens exhibits a much stronger affinity for the Na + ion compared to ligands from other EPS; therefore, the deprotonated carboxylic sites of EPS from P. fluorescens are hypothesized to be mostly bound by Na + in solution.

a b s t r a c tThe increase in resistance to contaminants can result in the loss of genetic diversity of impacted populations. In this work, the effects of acid mine drainage (AMD) on the genetic diversity and structure of a historically exposed population of Daphnia longispina were evaluated using amplified fragment length polymorphism (AFLP) analysis. Individual sensitivity to acute copper exposure was determined in order to characterize the populations in terms of metal tolerance and in an attempt to identify possible contaminant indicative bands (CIB). No reduction in genetic diversity was found in the AMD impacted site population, in comparison to two reference populations. However, the analysis of molecular variance indicated a significant genetic differentiation from the two reference populations and a significant correlation between individual genetic distance and tolerance. The different average tolerance of individuals presenting one specific AFLP band indicated the existence of one putative CIB.

SUMMARY. The estimated average number of bacteria in the gut of laboratory‐cultured Nais variabilis was 100.4 × 104. This compares with values of 6.7 × 104 and 32.8 × 104, respectively, for N. variabilis and N. barbata obtained from a river. Comparison of the viability of heterotrophic bacteria in the food and gut of N. variabilis indicated a decline in viability of up to 99.6% during the passage of bacteria through the gut. The estimated gut retention time was 39 ± 8 min at 18°C and therefore loss of viability is unlikely to be due to long retention in the gut. Loss of viability is, however, a prerequisite of bacterial digestion by the worm and provides circumstantial evidence that ingested bacteria are used as food. No conclusive evidence was obtained indicating (a) preferential ingestion of certain kinds of bacteria, (b) that the gut environment was selectively hostile to the particular kinds of bacteria studied or (c) that worms had a specialized gut micro‐flora.