<Emphasis Type="Italic">Salmonella</Emphasis> Isolated from Animals and Feed Production in Sweden Between 1993 and 1997

This paper presents Salmonella data from animals, feedstuffs and feed mills in Sweden between 1993 and 1997. During that period, 555 isolates were recorded from animals, representing 87 serotypes. Of those, 30 serotypes were found in animals in Sweden for the first time. The majority of all isolates from animals were S. Typhimurium (n = 91), followed by S. Dublin (n = 82). There were 115 isolates from cattle, 21 from broilers, 56 from layers and 18 from swine. The majority of these isolates were from outbreaks, although some were isolated at the surveillance at slaughterhouses. The number of isolates from the feed industry was similar to that of the previous 5-year period. Most of those findings were from dust and scrapings from feed mills, in accordance with the HACCP programme in the feed control programme. It can be concluded that the occurrence of Salmonella in animals and in the feed production in Sweden remained favourable during 1993–97.     

Continental-scale patterns of nutrient and fish effects on shallow lakes: synthesis of a pan-European mesocosm experiment

1. Results are analysed from 11 experiments in which effects of fish addition and nutrient loading on shallow lakes were studied in mesocosms. The experiments, five in 1998, six in 1999, were carried out in six lakes, distributed from Finland to southern Spain, according to a standard protocol. 2. Effects of the treatments on 29 standard chemical, phytoplankton and zooplankton variables are examined to assess the relative importance of bottom‐up (nutrient enrichment) and top‐down (fish predation) effects. For each year, the experiments in different locations are treated as replicates in a meta‐analysis. Results of individual experiments are then compared in terms of the patterns of significant influences of nutrient addition and fish predation with these overall results (the baseline), and between years in the same location. 3. The overall meta‐analysis gave consistent results across the 2 years, with nutrient loading influencing all of the chemical variables, and on average 31% of primary producer and 39% of zooplankton variables. In contrast, fish influenced none of the chemical variables, 11% of the primary producer and 44% of the zooplankton variables. Nutrient effects on the system were thus about three times greater than fish effects, although fish effects were not inconsiderable. 4. The relative importance of nutrients and fish in individual experiments often differed between years at the same location and effects deviated to varying degrees from the baseline. These deviations were treated as measures of consistency (predictability) of conclusions in repeat experiments. Consistency increased southwards and this is interpreted as a consequence of more variable annual weather northwards. 5. The influence of nutrient loading was greater southwards and this was probably manifested through naturally greater annual macrophyte abundance in warmer locations in consequence of the longer plant growing‐season. There was no trend in the relative importance of fish effects with latitude but this may partly be an artefact of the simple fish community used. These findings suggest that nutrient control should be a greater priority than biomanipulation in the restoration of eutrophicated shallow lakes in warm temperate regions. 6. Starting conditions affected the outcome of experiments. High initial concentrations of total phosphorus and planktonic chlorophyll a concentration (created by local conditions prior to the experiment) led to de‐emphasis of the importance of nutrient loading in the experiment.     

Warmer climates boost cyanobacterial dominance in shallow lakes

Dominance by cyanobacteria hampers human use of lakes and reservoirs worldwide. Previous studies indicate that excessive nutrient loading and warmer conditions promote dominance by cyanobacteria, but evidence from global scale field data has so far been scarce. Our analysis, based on a study of 143 lakes along a latitudinal transect ranging from subarctic Europe to southern South America, shows that although warmer climates do not result in higher overall phytoplankton biomass, the percentage of the total phytoplankton biovolume attributable to cyanobacteria increases steeply with temperature. Our results also reveal that the percent cyanobacteria is greater in lakes with high rates of light absorption. This points to a positive feedback because restriction of light availability is often a consequence of high phytoplankton biovolume, which in turn may be driven by nutrient loading. Our results indicate a synergistic effect of nutrients and climate. The implications are that in a future warmer climate, nutrient concentrations may have to be reduced substantially from present values in many lakes if cyanobacterial dominance is to be controlled.     

The establishment of 20 different human embryonic stem cell lines and subclones; a report on derivation, culture, characterisation and banking

This report summarises our efforts in deriving, characterising and banking of 20 different human embryonic stem cell lines. We have derived a large number of human embryonic stem cell lines between 2001 and 2005. One of these cell lines was established under totally xeno-free culture conditions. In addition, several subclones have been established, including a karyoptypical normal clone from a trisomic mother line. A master cell banking system has been utilised in concert with an extensive characterisation programme, ensuring a supply of high quality pluripotent stem cells for further research and development. In this report we also present the first data on a proprietary novel antibody, hES-Cellect, that exhibits high specificity for undifferentiated hES cells. In addition to the traditional manual dissection approach of propagating hES cells, we here also report on the successful approaches of feeder-free cultures as well as single cell cultures based on enzymatic digestion. All culture systems used as reported here have maintained the hES cells in a karyotypical normal and pluripotent state. These systems also have the advantage of being the principal springboards for further scale up of cultures for industrial or clinical applications that would require vastly more cells that can be produced by mechanical means.     

Properdin factor B (Bf) types in schizophrenia

The phenotype frequencies of properdin factor B (Bf) were studied in patients with (n = 47) and without (n = 66) a family history of schizophrenia and in controls. In patients with a family history of schizophrenia, a significant decrease of the FS type was found. No significant difference was found between patients without a family history of schizophrenia and controls.     

Determining the climate impact of food for use in a climate tax—design of a consistent and transparent model

The International Journal of Life Cycle Assessment - The aim of this study was to determine transparent food carbon footprint values for use in a climate tax, using a consistent methodology across...     

Metallation of the transition-state inhibitor N-methyl mesoporphyrin by ferrochelatase: implications for the catalytic reaction mechanism

Insertion of metals into various tetrapyrroles is catalysed by a group of enzymes called chelatases, e.g. nickel, cobalt, magnesium and ferro-chelatase. It has been proposed that catalytic metallation includes distorting the porphyrin substrate by the enzyme towards a transition state-like geometry in which at least one of the pyrrole rings will be available for metal chelation. Here, we present a study of metal insertion into the transition-state inhibitor of protoporphyrin IX ferrochelatase, N-methyl mesoporphyrin (N-MeMP), by time-resolved crystallography and mass spectrometry with and without the presence of ferrochelatase. The results show that metallation of N-MeMP has a very limited effect on the conformation of the residues that participate in porphyrin and metal binding. These findings support theoretical data, which indicate that product release is controlled largely by the strain created by metal insertion into the distorted porphyrin. The results suggest that, similar to non-catalytic metallation of N-MeMP, the ferrochelatase-assisted metallation depends on the ligand exchange rate for the respective metal. Moreover, ferrochelatase catalyses insertion of Cu(II) and Zn(II) into N-MeMP with a rate that is about 20 times faster than non-enzymatic metallation in solution, suggesting that the catalytic strategy of ferrochelatase includes a stage of acceleration of the rate of ligand exchange for the metal substrate. The greater efficiency of N-MeMP metallation by Cu(II), as compared to Zn(II), contrasts with the K(m) values for Zn(II) (17 microM) and Cu(II) (170 microM) obtained for metallation of protoporphyrin IX. We suggest that this difference in metal specificity depends on the type of distortion imposed by the enzyme on protoporphyrin IX, which is different from the intrinsic non-planar distortion of N-MeMP. A mechanism of control of metal specificity by porphyrin distortion may be general for different chelatases, and may have common features with the mechanism of metal specificity in crown ethers.     

Development of an in vitro test battery for the estimation of acute human systemic toxicity: An outline of the EDIT project. Evaluation-guided Development of New In Vitro Test Batteries

The aim of the Evaluation-guided Development of new In Vitro Test Batteries (EDIT) multicentre programme is to establish and validate in vitro tests relevant to toxicokinetics and for organ-specific toxicity, to be incorporated into optimal test batteries for the estimation of human acute systemic toxicity. The scientific basis of EDIT is the good prediction of human acute toxicity obtained with three human cell line tests (R(2) = 0.77), in the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) programme. However, the results from the MEIC study indicated that at least two other types of in vitro test ought to be added to the existing test battery to improve the prediction of human acute systemic toxicity - to determine key kinetic events (such as biotransformation and passage through biological barriers), and to predict crucial organ-specific mechanisms not covered by the tests in the MEIC battery. The EDIT programme will be a case-by-case project, but the establishment and validation of new tests will be carried through by a common, step-wise procedure. The Scientific Committee of the EDIT programme defines the need for a specific set of toxicity or toxicokinetic data. Laboratories are then invited to perform the defined tests in order to provide the "missing" data for the EDIT reference chemicals. The results obtained will be evaluated against the MEMO (the MEIC Monograph programme) database, i.e. against human acute systemic lethal and toxicity data. The aim of the round-table discussions at the 19th Scandinavian Society for Cell Toxicology (SSCT) workshop, held in Ringsted, Denmark on 6-9 September 2001, was to identify which tests are the most important for inclusion in the MEIC battery, i.e. which types of tests the EDIT programme should focus on. It was proposed that it is important to include in vitro methods for various kinetic events, such as biotransformation, absorption in the gut, passage across the blood-brain barrier, distribution volumes, protein binding, and renal clearance/accumulation. Models for target organ toxicity were also discussed. Because several of the outlier chemicals (paracetamol, digoxin, malathion, nicotine, paraquat, atropine and potassium cyanide) in the MEIC in vivo-in vitro evaluation have a neurotoxic potential, it was proposed that the development within the EDIT target organ programme should initially be focused on the nervous system.     

Humoral and cellular immune reactions against tumor cells in patients with urinary bladder carcinoma

Summary Serum IgG fractions from a large and homogenous group of patients with transitional cell carcinoma of the urinary bladder (TCC) were tested for their capacity to induce antibody-dependent cellular cytotoxicity (ADCC) with lymphocytes from healthy donors against a TCC-derived target cell and one derived from adenocarcinoma of the colon. Both targets have previously been shown to be of comparable susceptibility to cell-mediated lysis in vitro. Some of the IgG preparations showed strong and dose-dependent ADCC against either one or both targets, while others gave weak reactions or none at all. Similar results were obtained with IgG from a matched group of patients with prostatic carcinoma who were used as clinical controls (CC). In parallel experiments, lymphocytes taken from the two donor groups at the same time as the serum samples were tested for their direct cytotoxicity (CMC) against the two targets. CMC gave similar results to ADCC. The differences in cytotoxicity displayed by either IgG or lymphocytes from individual donors were analysed statistically, using nonparametric statistics. To avoid introducing bias due to arbitrary data selection, the entire set of results, comprising both high and low reactors, was included in the statistical assessment. ADCC of the TCC donors' IgG against the TCC target was significantly stronger than against the colon carcinoma and also significantly stronger than that of the control donors. Similarly, the TCC patients' lymphocytes displayed a significantly higher CMC against the TCC target than against the control targets. This was not seen when the lymphocytes from the patients with prostatic carcinoma were tested. When CMC and ADCC of individual donors were compared, a statistically significant correlation between these activities was seen in three of the four donor/target combinations. These results support earlier findings and suggest that a significant fraction of both the disease-related and the non-selective CMC (NK) displayed by cancer patients lymphocytes against allogeneic tumor cells in vitro reflects antibody-dependent reactions.     

Effects of 3-aminobenzamide on Chinese hamster cells treated with thymidine analogues and DNA-damaging agents. Chromosomal aberrations, mutations and cell-cycle progression

The nuclear enzyme, poly(ADP-ribose) synthetase is involved in the repair of damaged DNA. We report here the results obtained with 3-aminobenzamide (3AB), an inhibitor of this enzyme, on induced biological effects. 3AB increases the frequency of chromosomal aberrations induced by DMS, EMS, ENU, bleomycin and CldUrd. The magnitude of the effect is dependent on the type of chemical used, the combinations with DMS and EMS being the most potent ones. No potentiation was observed after treatment of cells with MMC. Mutation frequencies were determined on the HPRT locus and showed that 3AB did not increase the frequency of gene mutations induced by EMS, ENU and CldUrd. Cell-cycle progression is affected when cells are grown in medium containing CldUrd and 3AB, primarily when the inhibitor is present during the second cell cycle when substituted DNA becomes replicated. The extent of the effect depends on the amount of analogue incorporated and is independent of the presence of the analogue in the medium during the second cell cycle. Analysis of chromosomal aberrations in delayed G2 cells with the aid of the premature chromosome-condensation technique revealed numerous aberrations after incorporation of CldUrd and treatment with 3AB.