Informing the management of multiple stressors on estuarine ecosystems using an expert-based Bayesian Network model

The approach of applying stressor load limits or thresholds to aid estuarine management is being explored in many global case studies. However, there is growing concern regarding the influence of multiple stressors and their cumulative effects on the functioning of estuarine ecosystems due to the considerable uncertainty around stressor interactions. Recognising that empirical data limitations hinder parameterisation of detailed models of estuarine ecosystem responses to multiple stressors (suspended sediment, sediment mud and metal content, and nitrogen inputs), an expert driven Bayesian network (BN) was developed and validated. Overall, trends in estuarine condition predicted by the BN model were well supported by field observations, including results that were markedly higher than random (71-84% concordance), providing confidence in the overall model dynamics. The general BN framework was then applied to a case study estuary to demonstrate the model's utility for informing management decisions. Results indicated that reductions in suspended sediment loading were likely to result in improvements in estuarine condition, which was further improved by reductions in sediment mud and metal content, with an increased likelihood of high abundance of ecological communities relative to baseline conditions. Notably, reductions in suspended sediment were also associated with an increased probability of high nuisance macroalgae and phytoplankton if nutrient loading was not also reduced (associated with increased water column light penetration). Our results highlight that if stressor limit setting is to be implemented, limits must incorporate ecosystem responses to cumulative stressors, consider the present and desired future condition of the estuary of interest, and account for the likelihood of unexpected ecological outcomes regardless of whether the experts (or empirical data) suggest a threshold has or has not been triggered.

An evaluation of continuous subcutaneous infusions across seven NHS acute hospitals: is there potential for 48-hour infusions?

BACKGROUND

Continuous subcutaneous infusions (CSCIs) are commonly used in the United Kingdom as a way of administering medication to patients requiring symptom control when the oral route is compromised. These infusions are typically administered over 24 h due to currently available safety data. The ability to deliver prescribed medication by CSCI over 48 h may have numerous benefits in both patient care and health service resource utilisation. This service evaluation aims to identify the frequency at which CSCI prescriptions are altered at NHS Acute Hospitals.

METHODS

Pharmacists or members of palliative care teams at seven acute NHS hospitals recorded anonymised prescription data relating to the drug combination(s), doses, diluent and compatibility of CSCIs containing two or more drugs on a daily basis for a minimum of 2 days, to a maximum of 7 days.

RESULTS

A total of 1301 prescriptions from 288 patients were recorded across the seven sites, yielding 584 discrete drug combinations. Of the 584 combinations, 91% (n = 533) included an opioid. The 10 most-common CSCI drug combinations represented 37% of the combinations recorded. Median duration of an unchanged CSCI prescription across all sites was 2 days.

CONCLUSION

Data suggests medication delivered by CSCI over 48 h may be a viable option. Before a clinical feasibility study can be undertaken, a pharmacoeconomic assessment and robust chemical and microbiological stability data will be required, as will the assessment of the perceptions from clinical staff, patients and their families on the acceptability of such a change in practice.

Apoptosis and nucleosomes

Drs Berden and Koutouzov presented evidence that nucleosomes are antigens in lupus pathogenesis and that apoptotic cells are the source of nucleosomes. Berden's group measured persistence of circulating nucleosomes and nucleosome-antibody complexes in autoimmune mice and demonstrated nucleosomal deposition in skin of SLE patients as well as in renal lesions. Koutouzov reported that anti-nucleosomes are among the earliest autoantibodies in MRL+/+ mice, appearing several weeks before anti-DNA antibodies. Treatment of the mice with a pro-apoptotic drug, taxotere, accelerated autoantibody production and development of lesions. Herrmann proposed that persistent immunization results from reduced dead cell clearance and reduced production of immunosuppressive cytokines by defective scavenger macrophages. He also described accumulation of apoptotic cells in germinal follicles in SLE patients and attachment of nuclear antigens that are produced in apoptosis to the surface of follicular dendritic cells. Apoptosis-derived nucleosomes may be important in both the immunizing and effector arms of pathogenesis.

Expression of functional GABAA receptors in neuroendocrine gastropancreatic cells

Gastropancreatic neuroendocrine cells synthesize large amounts of gamma-aminobutyric acid (GABA). This amino acid neurotransmitter appears to be stored in and released from, vesicles similar to small synaptic vesicles. So far, the function of GABA in gastropancreatic, neuroendocrine cells has not been clarified. Previous work suggested that only pancreatic, glucagon-producing alpha 2 cells contain functional GABAA receptors. Using subunit-specific antibodies in sections of human antral mucosa, a human gastrinoma and rat pancreas, we show that expression of GABAA receptors is abundant in gastropancreatic, neuroendocrine cells. Using the patch-clamp technique in the whole-cell mode we demonstrate that both the rat insulinoma cell line RIN 38 and the amphicrine cell line AR42J express functional GABAA receptors, which are characterized by a relatively low benzodiazepine and Zn2+ sensitivity and by an insensitivity to the inverse benzodiazepine agonist 6,7-alpha-methoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM). In contrast to neurons, activation of GABAA receptors leads to a membrane depolarization. This depolarization presumably activates voltage-gated Ca2+ channels, resulting in an increase in cytosolic Ca2+ concentration, [Ca2+]i, as shown with the fluorimetric dye fura-2. The combination of GABA release, GABAA receptor activation and the [Ca2+]i increase could constitute an autocrine mechanism, modulating the release of hormones such as gastrin, insulin and somatostatin.

Purification and characterization of the restriction endonuclease RsrI, an isoschizomer of EcoRI

Rhodobacter sphaeroides strain 630 produces restriction enzyme RsrI which is an isoschizomer of EcoRI. We have purified this enzyme and initiated a comparison with the EcoRI endonuclease. The properties of RsrI are consistent with a reaction mechanism similar to that of EcoRI: the position of cleavage within the -GAATTC-site is identical, the MgCl2 optimum for the cleavage is identical, and the pH profile is similar. Methylation of the substrate sequence by the EcoRI methylase protects the site from cleavage by the RsrI endonuclease. RsrI cross-reacts strongly with anti-EcoRI serum indicating three-dimensional structural similarities. We have determined the sequence of 34 N terminal amino acids for RsrI and this sequence possesses significant similarity to the EcoRI N terminus.