Microglial activation in the injured and healthy brain: what are we really talking about? Practical and theoretical issues associated with the measurement of changes in microglial morphology.

Recently it has become apparent that microglia play a role not only in responding to insults within the central nervous system but also in responding to changes in synaptic activity and potentially modulating synaptic function. This has led to an enormous expansion of interest in how microglia respond to both pathological and nonpathological challenges, with activities that are associated with unique morphological transformations. Examining changes in microglial morphology can provide direct insight into the cells' functional activities, as morphological status is recognized to be tightly coupled with function. Despite these advances in knowledge, many of the image-based morphometric procedures used to investigate changes in microglial morphology have not kept pace. This has created a situation in which morphometric approaches that have been extensively employed in the past can no longer provide accurate information on the complex transformations that microglia can undergo, particularly under non-pathological conditions. This review critically examines the strengths and weaknesses of existing morphometric analysis procedures. This review further examines efforts to improve the utility of existing approaches and discusses new developments, such as digital reconstruction, that yield more accurate and specific information on how microglia remodel themselves. Ultimately, an improved understanding of the strengths and limitations of existing, and emerging, morphometric approaches will greatly facilitate efforts to understand how microglia remodel themselves in response to the full spectrum of challenges that they are known to encounter.

Potential environmental consequences of administration of ectoparasiticides to sheep.

Sheep ectoparasiticides, which include the synthetic pyrethroids, the organophosphates, the 'insect'-growth regulators, the formamidines and the spinocyns, enter into the environment primarily through disposal of dip or fleece scours, as well as with contaminated faeces and urine. Due to the large quantities of spent dip, risks associated with environmental contamination are high. Synthetic pyrethroids and organophosphates pose risks to dung, soil and aquatic fauna; concerns over potential ecotoxicity to vertebrates and invertebrates have resulted in the cessation of their use in many countries. There is very little information regarding the ecotoxicity of 'insect'-growth regulators, formamidines or spinocyns, with no studies focussing on sheep. Here, the impact of sheep ectoparasiticides is discussed in terms of their potential to enter into the environment, their toxicity and their impact on ecosystem functioning. Where there are no data for excretion or toxicity of the ectoparasiticides used in sheep production, examples to demonstrate potential impacts are taken from laboratory ecotoxicity tests and the cattle literature, as well on work with foliar insecticides. Future research priorities are suggested to allow assessment of the environmental consequences of sheep ectoparasiticide treatments, which are essential for future sustainable sheep production.

Potential environmental consequences of administration of anthelmintics to sheep.

Anthelmintics, veterinary medicines for the control of endoparasites, enter into the environment largely through faeces of the treated animals. Sheep dung is a patchily distributed, ephemeral resource, with a functionally important decomposer community. The nature of this community and the pharmacokinetics of anthelmintics in sheep mean that the ecotoxic impacts of these drugs in sheep dung may differ markedly from those in cattle dung, where most research has been focussed. The period of maximum residue excretion is generally more transient in sheep than cattle dung, but low-level excretion may continue for longer, giving the potential for extended sub-lethal effects. Here, the environmental impacts of sheep anthelmintics, as well as alternative endoparasite control methods are reviewed. Impacts are discussed in terms of the potential for residues to enter into the environment, the toxicity and the impact on ecosystem functioning at an appropriate scale. Future research priorities are also discussed; these include the need for studies of the functional contributions of dung-colonising species, as well as the development of higher-tier ecotoxicological methods bridging the gap between laboratory and field experiments. Large-scale and long-term studies, including the development of appropriate models, are necessary to allow the consequences of anthelmintic administration to be assessed, particularly within the remit of sustainable animal production.

Area-wide impact of macrocyclic lactone parasiticides in cattle dung.

Following the treatment of cattle with veterinary parasiticides and insecticides, residues are excreted into the dung in concentrations that may be toxic to functionally important dung-colonizing insects. In the dung, these residues cause a range of well-studied lethal and sub-lethal effects, the magnitudes of which vary with the compound used, mode of administration and concentration, and the insect species in question. Particular concern has been associated with the use of macrocyclic lactones in this context. Loss of insect colonizers may delay pat decomposition, but field studies report contrasting results that reflect confounding factors such as weather conditions, pat moisture content, pat location, time of year and dung insect species phenologies. The question of fundamental concern is whether the impacts seen in experimental or laboratory studies are likely to have a functional impact on insect populations, community interactions and the economically important process of dung decomposition. Recent studies which have attempted to address these wider, landscape-level impacts in temperate ecosystems are reviewed here. These show that the extent to which chemical residues may have any sustained ecological impact will depend on both a range of farm management factors, such as the temporal and spatial patterns of chemical use, the number of animals treated and the choice of active ingredient, and a range of insect-related factors, such as abundance, population dynamics and dispersal rates. However, they also demonstrate that considerable uncertainty remains about the likely extent of such effects and that current data are insufficient to support firm conclusions regarding sustained pasture-level effects. More large-scale, longterm field experiments are required, particularly in relation to insect dispersal and functional interactions within the dung insect community.

Pharmacological interventions for the prevention of relapse in bipolar disorder: a systematic review of controlled trials.

We conducted a systematic review and meta-analysis of randomised and quasi-randomised controlled trials evaluating all clinically relevant pharmacological interventions for the prevention of relapse in people with bipolar disorder. Thirty-four trials were included in the review. Direct comparisons with placebo and with lithium were available for most drugs. In addition, there were direct comparisons of valproate vs. olanzapine, imipramine vs. lithium plus imipramine, olanzapine plus mood stabilisers vs. mood stabilisers and perphenazine plus mood stabilisers vs. mood stabilisers. Methodological quality varied across studies and the strength of evidence was not equal for all treatments or for all comparisons. There is evidence from placebo-controlled trials for the efficacy of lithium, valproate and lamotrigine as maintenance therapy for the prevention of relapse in bipolar disorder. Three drugs have a significant effect in the prevention of manic relapses (lithium, olanzapine and aripiprazole) and three in the prevention of depressive symptoms (valproate, lamotrigine and imipramine). Imipramine is little used in practice, because of concern about adverse effects. The significant effects of olanzapine and aripiprazole were demonstrated in selected responsive bipolar I patients only. Despite widespread use in clinical practice, there is little evidence to support the efficacy of combination therapy.

A systematic review and economic model of the clinical effectiveness and cost-effectiveness of interventions for preventing relapse in people with bipolar disorder.

OBJECTIVES: To determine the clinical effectiveness and cost-effectiveness of pharmacological and/or psychosocial interventions for the prevention of relapse in people with bipolar disorder. DATA SOURCES: Major electronic databases were searched up to September 2005. REVIEW METHODS: Systematic reviews were undertaken on the clinical and economic effectiveness of treatments. An analysis was performed using the methods of mixed treatment comparison (MTC) to enable indirect comparisons to be made between the treatments. An economic model of treatments for the prevention of relapse in bipolar disorder was developed. RESULTS: Forty-five trials were included in the clinical effectiveness review; all but one studied adults. This review found that for the prevention of all relapses, lithium, valproate, lamotrigine and olanzapine performed better than placebo, with lithium and lamotrigine having the strongest evidence. For depressive relapse prevention, valproate, lamotrigine and imipramine performed better than placebo, with evidence strongest for lamotrigine and weakest for imipramine. For manic relapses, lithium and olanzapine performed significantly better than placebo. The MTC found that the best treatment for bipolar I patients with mainly depressive symptoms was valproate, followed by lithium plus imipramine. For bipolar I patients with mainly manic symptoms, olanzapine was the best treatment. From the studies investigating psychosocial interventions, there were few data for each comparison and outcome. The evidence suggests that cognitive behaviour therapy (CBT), in combination with usual treatment, is effective for the prevention of relapse. Group psychoeducation and possibly family therapy may also have roles as adjunctive therapy for preventing relapse. The results from the decision analytic model developed on the cost-effectiveness of long-term maintenance treatments of bipolar I patients suggest that the choice of treatment is dependent upon a number of factors: the previous episode history of a patient and the mortality benefit assumed for lithium strategies. The results from the base-case analysis for patients with a recent history of depression suggest that valproate, lithium and the combination of lithium and imipramine are potentially cost-effective depending upon the amount that a decision-maker is willing to pay for additional health gain. Using conventional amounts that the NHS is prepared to pay for health gain, then the lithium-based strategies appear to be potentially cost-effective for this group. For patients with a recent history of mania, the choice of pharmacological intervention appears to be between olanzapine and lithium monotherapy. Again using conventional threshold as a reference point, the results suggest that lithium is the most cost-effective therapy. Excluding the additional mortality benefit associated with lithium-based strategies resulted in all treatments for patients with a recent history of a depressive episode being dominated by valproate and, in the case of patients with a recent history of a manic episode, by olanzapine. CONCLUSIONS: Lithium, valproate, lamotrigine and olanzapine are effective as maintenance therapy for the prevention of relapse in bipolar disorder. Olanzapine and lithium are efficacious for the prevention of manic relapses and valproate, lamotrigine and imipramine for the prevention of depressive relapse. There is some evidence that CBT, group psychoeducation and family therapy might be beneficial as adjuncts to pharmacological maintenance treatments. Insufficient information is available regarding the relative tolerability of the treatments or their relative effects on suicide rate and mortality. For patients with a recent depressive episode, valproate, lithium monotherapy and the combination of lithium and imipramine are potentially cost-effective. For patients with a recent manic episode, olanzapine and lithium monotherapy are potentially cost-effective. The cost-effectiveness estimates in both groups of patients were shown to be sensitive to the assumption of a reduced suicidal risk associated with lithium-based strategies. Further research is needed into the adverse effects of all treatments and the differential effects of agents. Good-quality trials of valproate, of combination therapy, e.g. lithium plus a selective serotonin reuptake inhibitor antidepressant, of psychosocial interventions and of the disorder in children are also required.

Effect of beta-cell toxins on genetically engineered insulin-secreting cells.

The betacyte is a genetically engineered insulin-secreting liver cell line that is glucose responsive. Whether this cell is affected by specific beta-cell toxins is unknown. To explore this possibility we exposed these cells and those from the NIT-1 beta-cell line (positive controls) to the toxins streptozotocin (STZ, 2.5-20 mM), alloxan (ALL, 2.5-20 mM), and pentamidine (PENT, 10(-6)-1 mM). STZ and ALL were added for 1 h and pentamidine for 24 h. Insulin secretion from betacytes during a period of 5 h after removal of the toxin was inhibited only by pentamidine; all agents were inhibitory to NIT-1 cells. Glucose metabolism, as determined by a colorimetric MTT reduction assay, was adversely affected in betacytes by ALL (20 mM) and PENT (1 mM), and in NIT-1 cells by STZ (20 mM) as well as by ALL (2.5 mM) and PENT (1 mM). The magnitude of inhibition was less for the betacytes-58 v. 99%. Confluence of cells in culture wells and cell viability as assessed by the fluorochromes propidium iodide and acridine orange was reduced to a lesser extent for the betacytes than for the NIT-1 cells. The metabolic and microscopic effects of the toxins were unchanged in the betacyte from those in the liver cell line, HEP G2, from which the betacyte was engineered. These results of general resistance of the betacyte to beta-cell toxins with differing modes of action offer hope that this cell, or cells created in a similar manner from primary hepatocytes, may be at least partly resistant to the adverse effect of beta-cell toxins involved in autoimmune destruction of the pancreas. This increases the potential of the use of these cells for reversal of diabetes.

Gene therapy of diabetes: glucose-stimulated insulin secretion in a human hepatoma cell line (HEP G2ins/g).

In order to design a feasible somatic cell gene delivery system for the treatment of type I diabetes, a suitable cell type needs to be determined. We have previously shown that the stable transfection of the full-length insulin cDNA into the human liver cell line, (HEP G2ins) resulted in synthesis, storage and acute regulated release of insulin to analogues of cAMP, but not to the physiological stimulus glucose. In attempting to explain the lack of glucose responsiveness of the HEP G2ins cells we have stably transfected these cells with the human islet glucose transporter GLUT 2 (HEP, G2ins/g cells). The HEP G2ins/g cell clones exhibit glucose-stimulated insulin secretion and glucose potentiation of the secretory response to nonglucose secretagogues. While glucose responsiveness commenced at a lower concentration than normal islets, a secretion curve approaching normal physiological conditions was generated. Immunoelectron microscopy revealed the presence of insulin-containing granules, similar in size and appearance to those of the normal beta cell. These results demonstrate that while it is most likely that the HEP G2ins/g cell line predominantly secretes insulin via the constitutive pathway, significant acute regulated release was seen in response to glucose, and thus represents significant progress in the creation of a genetically engineered 'artificial beta cell' from a human hepatocyte cell line.