From Molecules to Mind: Mechanisms of Action of Electroconvulsive Therapy

(Reprinted with permission from Acta Psychatrica Scandinavica (John Wiley & Sons, Ltd.); ©John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Acta Psychiatrica Scandinavica 2018: 138:177-179).

Kynurenine pathway metabolism and the neurobiology of treatment-resistant depression: Comparison of multiple ketamine infusions and electroconvulsive therapy

Current first-line antidepressants can take weeks or months to decrease depressive symptoms. Low dose ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, shows potential for a more rapid antidepressant effect, with efficacy also evident in previously treatment-resistant populations. However, a greater understanding of the physiological mechanisms underlying such effects is required. We assessed the potential impact of ketamine infusion on neurobiological drivers of kynurenine pathway metabolism in major depression (HPA axis hyperactivity, inflammation) in patients with treatment-resistant depression compared to gender-matched healthy controls. Furthermore, we assessed these biomarkers before and after electroconvulsive therapy (ECT), which is currently the gold standard for management of treatment-resistant depression. As previously demonstrated, treatment with ketamine and ECT was associated with improved depressive symptoms in patients. At baseline, waking cortisol output was greater in the ECT cohort, kynurenine was greater in the ketamine cohort, and kynurenic acid was lower in patients compared to healthy controls, although inflammatory markers (IL-6, IL-8, IL-10 or IFN-γ) were similar in patients and controls. Furthermore, in patients who responded to ECT, the cortisol awakening response was decreased following treatment. Despite a trend towards reduced kynurenine concentrations in those who responded to ketamine, ketamine was not associated with significant alterations in any of the biomarkers assessed.

Peripheral blood microRNA and VEGFA mRNA changes following electroconvulsive therapy: implications for psychotic depression

OBJECTIVE

MicroRNAs are short, non-coding molecules that regulate gene expression. Here, we investigate the role of microRNAs in depression and electroconvulsive therapy (ECT).

METHODS

We performed three studies: a deep sequencing discovery-phase study of miRNA changes in whole blood following ECT (n = 16), followed by a validation study in a separate cohort of patients pre-/post-ECT (n = 37) and matched healthy controls (n = 34). Changes in an experimentally validated gene target (VEGFA) were then analysed in patients pre-/post-ECT (n = 97) and in matched healthy controls (n = 53).

RESULTS

In the discovery-phase study, we found no statistically significant differences in miRNA expression from baseline to end of treatment in the group as a whole, but post hoc analysis indicated a difference in patients with psychotic depression (n = 3). In a follow-up validation study, patients with psychotic depression (n = 7) had elevated baseline levels of miR-126-3p (t = 3.015, P = 0.006) and miR-106a-5p (t = 2.598, P = 0.025) compared to healthy controls. Following ECT, these differences disappeared. Baseline VEGFA levels were significantly higher in depressed patients compared to healthy controls (F(1,144) = 27.688, P = <0.001). Following ECT, there was a significant change in VEGFA levels in the psychotic group only (t = 2.915, P = 0.010).

CONCLUSION

Molecular differences (miRNA and VEGFA) may exist between psychotic and non-psychotic depression treated with ECT.

Electroconvulsive therapy modulates plasma pigment epithelium-derived factor in depression: a proteomics study

Electroconvulsive therapy (ECT) is the most effective treatment for severe depression, yet its mechanism of action is not fully understood. Peripheral blood proteomic analyses may offer insights into the molecular mechanisms of ECT. Patients with a major depressive episode were recruited as part of the EFFECT-Dep trial (enhancing the effectiveness of electroconvulsive therapy in severe depression; ISRCTN23577151) along with healthy controls. As a discovery-phase study, patient plasma pre-/post-ECT (n=30) was analyzed using 2-dimensional difference in gel electrophoresis and mass spectrometry. Identified proteins were selected for confirmation studies using immunodetection methods. Samples from a separate group of patients (pre-/post-ECT; n=57) and matched healthy controls (n=43) were then used to validate confirmed changes. Target protein mRNA levels were also assessed in rat brain and blood following electroconvulsive stimulation (ECS), the animal model of ECT. We found that ECT significantly altered 121 protein spots with 36 proteins identified by mass spectrometry. Confirmation studies identified a post-ECT increase (P<0.01) in the antiangiogenic and neuroprotective mediator pigment epithelium-derived factor (PEDF). Validation work showed an increase (P<0.001) in plasma PEDF in depressed patients compared with the controls that was further increased post-ECT (P=0.03). PEDF levels were not associated with mood scores. Chronic, but not acute, ECS increased PEDF mRNA in rat hippocampus (P=0.02) and dentate gyrus (P=0.03). This study identified alterations in blood levels of PEDF in depressed patients and further alterations following ECT, as well as in an animal model of ECT. These findings implicate PEDF in the biological response to ECT for depression.

Bitemporal v. high-dose right unilateral electroconvulsive therapy for depression: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Brief-pulse electroconvulsive therapy (ECT) is the most acutely effective treatment for severe depression though concerns persist about cognitive side-effects. While bitemporal electrode placement is the most commonly used form worldwide, right unilateral ECT causes less cognitive side-effects though historically it has been deemed less effective. Several randomized trials have now compared high-dose (>5× seizure threshold) unilateral ECT with moderate-dose (1.0-2.5× seizure threshold) bitemporal ECT to investigate if it is as effective as bitemporal ECT but still has less cognitive side-effects. We aimed to systematically review these trials and meta-analyse clinical and cognitive outcomes where appropriate.

METHOD

We searched PubMed, PsycINFO, Web of Science, Cochrane Library and EMBASE for randomized trials comparing these forms of ECT using the terms 'electroconvulsive' OR 'electroshock' AND 'trial'.

RESULTS

Seven trials (n = 792) met inclusion criteria. Bitemporal ECT did not differ from high-dose unilateral ECT on depression rating change scores [Hedges's g = -0.03, 95% confidence interval (CI) -0.17 to 0.11], remission (RR 1.06, 95% CI 0.93-1.20), or relapse at 12 months (RR 1.42, 95% CI 0.90-2.23). There was an advantage for unilateral ECT on reorientation time after individual ECT sessions (mean difference in minutes = -8.28, 95% CI -12.86 to -3.70) and retrograde autobiographical memory (Hedges's g = -0.46, 95% CI -0.87 to -0.04) after completing an ECT course. There were no differences for general cognition, category fluency and delayed visual and verbal memory.

CONCLUSIONS

High-dose unilateral ECT does not differ from moderate-dose bitemporal ECT in antidepressant efficacy but has some cognitive advantages.

Serum BDNF as a peripheral biomarker of treatment-resistant depression and the rapid antidepressant response: A comparison of ketamine and ECT

BACKGROUND

Ketamine is associated with rapid antidepressant efficacy but the biological mechanisms underpinning this effect are unclear. Serum brain-derived neurotrophic factor (sBDNF) is a potential circulating biomarker of treatment-resistant depression (TRD) and ketamine response but it is unclear if this is a common target of both ketamine and electroconvulsive therapy (ECT), the current gold standard for TRD. Moreover, the impact of multiple ketamine infusions on sBDNF has not yet been established.

METHODS

Thirty five TRD patients with a current DSM-IV diagnosis of recurrent depressive disorder received up to 12 ECT sessions (N=17) or up to three intravenous infusions of low-dose (0.5mg/kg) ketamine (N=18). Blood samples were taken over the course of the study for assessment of sBDNF. Symptom severity and response were monitored using the 17-item Hamilton Depression Rating Scale (HDRS). sBDNF was assessed in 20 healthy controls to allow comparison with TRD patients.

RESULTS

As expected, sBDNF was lower in TRD patients at baseline compared to healthy controls. Ketamine and ECT treatment were both associated with significant reductions in depressive symptoms. However, sBDNF was significantly elevated only at one week following the first ketamine infusion in those classified as responders one week later. sBDNF was not elevated following subsequent infusions. ECT reduced depressive symptoms, as expected, but was not associated with an enhancement in BDNF.

LIMITATIONS

Patients continued with their psychotropic medications throughout this trial.

CONCLUSIONS

SBDNF normalisation does not appear to be a prerequisite for symptomatic improvement in TRD following ketamine or ECT treatment.

When less is more--microRNAs and psychiatric disorders

OBJECTIVE

MicroRNAs are small non-coding RNA molecules that regulate gene expression, including genes involved in neuronal function and plasticity that have relevance for brain function and mental health. We therefore performed a systematic review of miRNAs in general adult psychiatric disorders.

METHOD

Systematic searches in PubMed/MEDLINE and Web of Science were conducted to identify published clinical articles on microRNAs in general adult psychiatric disorders. We also reviewed references from included articles.

RESULTS

There is mounting evidence of microRNAs' regulatory roles in a number of central nervous system processes, including neurogenesis and synaptic plasticity. The majority of clinical studies of microRNAs in psychiatric disorders are in schizophrenia, where a number of specific microRNAs have been identified in separate studies. There is some evidence of marked downregulation of some microRNAs in affective disorders. Treatment with antidepressants appears to upregulate microRNA levels. There is currently little evidence from human studies in anxiety, addiction or other psychiatric disorders.

CONCLUSION

MicroRNA research in psychiatry is currently in a nascent period, but represents an emerging and exciting area, with the potential to clarify molecular mechanisms of disease and identify novel biomarkers and therapeutic agents.

Reduced expression of glucocorticoid-inducible genes GILZ and SGK-1: high IL-6 levels are associated with reduced hippocampal volumes in major depressive disorder

Neuroplasticity may have a core role in the pathophysiology of major depressive disorder (MDD), a concept supported by experimental studies that found that excessive cortisol secretion and/or excessive production of inflammatory cytokines impairs neuronal plasticity and neurogenesis in the hippocampus. The objective of this study was to examine how changes in the glucocorticoid and inflammatory systems may affect hippocampal volumes in MDD. A multimodal approach with structural neuroimaging of hippocampus and amygdala, measurement of peripheral inflammatory proteins interleukin (IL)-6 and C-reactive protein (CRP), glucocorticoid receptor (GR) mRNA expression, and expression of glucocorticoid-inducible genes (glucocorticoid-inducible genes Leucin Zipper (GILZ) and glucocorticoid-inducible kinase-1 (SGK-1)) was used in 40 patients with MDD and 43 healthy controls (HC). Patients with MDD showed smaller hippocampal volumes and increased inflammatory proteins IL-6 and CRP compared with HC. Childhood maltreatment was associated with increased CRP. Patients with MDD, who had less expression of the glucocorticoid-inducible genes GILZ or SGK-1 had smaller hippocampal volumes. Regression analysis showed a strong positive effect of GILZ and SGK-1 mRNA expression, and further inverse effects of IL-6 concentration, on hippocampal volumes. These findings suggest that childhood maltreatment, peripheral inflammatory and glucocorticoid markers and hippocampal volume are interrelated factors in the pathophysiology of MDD. Glucocorticoid-inducible genes GILZ and SGK-1 might be promising candidate markers for hippocampal volume changes relevant for diseases like MDD. Further studies need to explore the possible clinical usefulness of such a blood biomarker, for example, for diagnosis or prediction of therapy response.

Regional variation in electroconvulsive therapy use

Although electroconvulsive therapy (ECT) is the most powerful treatment for depression, substantial variability in use has been described in Ireland. The Mental Health Commission collects usage data from approved centres but does not include home addresses or independent sector patients. Therefore, estimates of regional variation cannot be accurate, e.g. 145 (35% of total) independent sector patients were omitted from their 2008 analysis. When public and independent sector patients are combined inter-regional variation for 2008 is more than halved (chi-squared decreased from 83 to 30), with Western region contributing most to variation (chi-squared = 43). Ratio of ECT programmes to depressed admissions correlated negatively with rate for depressed admissions (r = -0.53, p = 0.01), while depressed admission numbers correlated with acute beds per area (r = 0.68, p = 0.001). Regional variation in ECT is less than previously reported; service factors probably account for much of this with smaller centres admitting severely ill patients more likely to require ECT.

Amyotrophic lateral sclerosis mutant vesicle-associated membrane protein-associated protein-B transgenic mice develop TAR-DNA-binding protein-43 pathology

Cytoplasmic ubiquitin-positive inclusions containing TAR-DNA-binding protein-43 (TDP-43) within motor neurons are the hallmark pathology of sporadic amyotrophic lateral sclerosis (ALS). TDP-43 is a nuclear protein and the mechanisms by which it becomes mislocalized and aggregated in ALS are not properly understood. A mutation in the vesicle-associated membrane protein-associated protein-B (VAPB) involving a proline to serine substitution at position 56 (VAPBP56S) is the cause of familial ALS type-8. To gain insight into the molecular mechanisms by which VAPBP56S induces disease, we created transgenic mice that express either wild-type VAPB (VAPBwt) or VAPBP56S in the nervous system. Analyses of both sets of mice revealed no overt motor phenotype nor alterations in survival. However, VAPBP56S but not VAPBwt transgenic mice develop cytoplasmic TDP-43 accumulations within spinal cord motor neurons that were first detected at 18 months of age. Our results suggest a link between abnormal VAPBP56S function and TDP-43 mislocalization.

A randomized controlled trial with 4-month follow-up of adjunctive repetitive transcranial magnetic stimulation of the left prefrontal cortex for depression

BACKGROUND

Effectiveness of repetitive transcranial magnetic stimulation (rTMS) for major depression is unclear. The authors performed a randomized controlled trial comparing real and sham adjunctive rTMS with 4-month follow-up.

METHOD

Fifty-nine patients with major depression were randomly assigned to a 10-day course of either real (n=29) or sham (n=30) rTMS of the left dorsolateral prefrontal cortex (DLPFC). Primary outcome measures were the 17-item Hamilton Depression Rating Scale (HAMD) and proportions of patients meeting criteria for response (50% reduction in HAMD) and remission (HAMD8) after treatment. Secondary outcomes included mood self-ratings on Beck Depression Inventory-II and visual analogue mood scales, Brief Psychiatric Rating Scale (BPRS) score, and both self-reported and observer-rated cognitive changes. Patients had 6-week and 4-month follow-ups.

RESULTS

Overall, Hamilton Depression Rating Scale (HAMD) scores were modestly reduced in both groups but with no significant groupxtime interaction (p=0.09) or group main effect (p=0.85); the mean difference in HAMD change scores was -0.3 (95% CI -3.4 to 2.8). At end-of-treatment time-point, 32% of the real group were responders compared with 10% of the sham group (p=0.06); 25% of the real group met the remission criterion compared with 10% of the sham group (p=0.2); the mean difference in HAMD change scores was 2.9 (95% CI -0.7 to 6.5). There were no significant differences between the two groups on any secondary outcome measures. Blinding was difficult to maintain for both patients and raters.

CONCLUSIONS

Adjunctive rTMS of the left DLPFC could not be shown to be more effective than sham rTMS for treating depression.

The clinical effectiveness and cost of repetitive transcranial magnetic stimulation versus electroconvulsive therapy in severe depression: a multicentre pragmatic randomised controlled trial and economic analysis

OBJECTIVE

To investigate if repetitive transcranial magnetic stimulation (rTMS) was as effective as electroconvulsive therapy (ECT) in treating major depressive episodes and to perform a cost-effectiveness analysis.

DESIGN

A single-blind pragmatic multicentre randomised controlled trial (RCT) with 6 months of follow-up to test equivalence of rTMS with ECT.

SETTING

The South London and Maudsley NHS Trust and Pembury Hospital in the Invicta Mental Health Trust in Kent.

PARTICIPANTS

Right-handed adult patients referred for ECT for treatment of a major depressive episode (DSM-IV) were assessed. During the 2.5-year trial period, 260 patients were referred for ECT, of whom 46 entered the trial. The main reason for not entering the trial was not consenting to ECT while being formally treated under the UK Mental Health Act 1983.

INTERVENTIONS

Patients were randomised to receive a 15-day course of rTMS of the left dorsolateral prefrontal cortex (n = 24) or a course of ECT (n = 22).

MAIN OUTCOME MEASURES

Patients were assessed before randomisation, at end of treatment and at the 6-month follow-up. Primary outcome measures were the 17-item Hamilton Rating Scale for Depression (HRSD) and proportion of remitters (defined as HRSD score <or=8) at the end-of-treatment time point. Secondary outcomes included self-ratings for mood on the Beck Depression Inventory-II (BDI-II) and visual analogue mood scales (VAMS), the Brief Psychiatric Rating Scale (BPRS), plus subjective and objective side-effects. Low scores on the BDI-II, VAMS and BPRS are positive in terms of health. The results were analysed on an intention-to-treat basis. Cost data were collected using the Client Service Receipt Inventory and the Short Form with 36 Items was used to obtain quality of life measures. Health economic outcomes were cost of treatments, costs incurred during the 6-month follow-up period and gains in quality-adjusted life-years (QALYs).

RESULTS

One patient was lost to follow-up at end of treatment and another eight at 6 months. The end-of-treatment HRSD scores were lower for ECT, with 13 (59%) achieving remission compared with four (17%) in the rTMS group. However, HRSD scores did not differ between groups at 6 months. BDI-II, VAMS and BPRS scores were lower for ECT at end of treatment and remained lower after 6 months. Improvement in subjective reports of side-effects following ECT correlated with antidepressant response. There was no difference between the two groups before or after treatment on global measures of cognition. Although individual treatment session costs were lower for rTMS than ECT, the cost for a course of rTMS was not significantly different from that for a course of ECT as more rTMS sessions were given per course. Service costs were not different between the groups in the subsequent 6 months but informal care costs were significantly higher for the rTMS group and contributed substantially to the total cost for this group during the 6-month follow-up period. There also was no difference in gain in QALYs for ECT and rTMS patients. Analysis of cost-effectiveness acceptability curves demonstrated that rTMS has very low probability of being more cost-effective than ECT.

CONCLUSIONS

ECT is a more effective and potentially cost-effective antidepressant treatment than 3 weeks of rTMS as administered in this study. Optimal treatment parameters for rTMS need to be established for treating depression. More research is required to refine further the administration of ECT in order to reduce associated cognitive side-effects while maintaining its effectiveness. There is a need for large-scale, adequately powered RCTs comparing different forms of ECT. The next generation of randomised trials of rTMS should also seek to compare treatment variables such as stimulus intensity, number of stimuli administered and duration of treatment, with a view to quantifying an effect size for antidepressant action.

Expression of the Fe65 adapter protein in adult and developing mouse brain

Fe65 is a multimodular adaptor protein expressed mainly in the nervous system. Fe65 binds to the Alzheimer's disease amyloid precursor protein (APP) and the interaction is mediated via a phosphotyrosine binding domain in Fe65 and the carboxy-terminal cytoplasmic domain of APP. Fe65 modulates trafficking and processing of APP, including production of the beta-amyloid peptide that is believed to be central to the pathogenesis of Alzheimer's disease. Fe65 also facilitates translocation of a carboxy-terminal fragment of APP to the nucleus and is required for APP-mediated transcription events. In addition, Fe65 functions in regulation of the actin cytoskeleton and cell movement. Here we report the distribution profile of Fe65 immunoreactivity in adult mouse brain. Fe65 expression was found to be widespread in neurones in adult brain. The areas of highest expression included regions of the hippocampus in which the earliest abnormalities of Alzheimer's disease are detectable. Fe65 was also highly expressed in the cerebellum, thalamus and selected brain stem nuclei. Fe65 was evident in a sub-set of astrocytes within the stratum oriens and radiatum in the hippocampus. Expression of Fe65 was found to be developmentally regulated with levels reducing after embryonic day 15 and increasing again progressively from post-partum day 10 up to adulthood, a developmental pattern that partially parallels that of APP. These data indicate a widespread distribution of Fe65 in neurones throughout mouse brain and also suggest that Fe65 may have functions independent of APP and any potential role in the pathogenesis of Alzheimer's disease.

Protein aggregates and dementia: is there a common toxicity?

This review considers some of the recent advances made in the understanding of the pathogenic proteins known to aggregate and be implicated in neurodegenerative dementing disorders. It concentrates on the two most obvious candidates for the role of toxic protein in Alzheimer's disease (AD)--beta-amyloid peptide and tau--but also considers other proteins in this disorder and in less common but equally devastating diseases.

A simple and effective separation and purification procedure for DNA fragments using dodecyltrimethylammonium bromide

In this work we describe a simple two step separation procedure for the separation and purification of short DNA fragments. The first step involves precipitating the DNA using the cationic surfactant dodecyltrimethylammonium bromide. Dodecyltrimethylammonium bromide, unlike cetyltrimethylammonium bromide will not precipitate DNA before complexation is complete thus providing a high purity DNA. The second step involves dissolution of the DNA-dodecyltrimethylammonium complex in 75% ethanol, followed by precipitation of the Sodium-DNA salt, by titrating in a salt solution. This method is particularly suited to purification of short fragments as it does not require high salt concentrations in the ethanol precipitation step, which can be damaging for short DNA. The ability of dodecyltrimethylammonium bromide to remove ethidium bromide from intercalation sites on the DNA is also discussed

The neuronal adaptor protein X11alpha interacts with the copper chaperone for SOD1 and regulates SOD1 activity

The neuronal adaptor protein X11alpha participates in the formation of multiprotein complexes and intracellular trafficking. It contains a series of discrete protein-protein interaction domains including two contiguous C-terminal PDZ domains. We used the yeast two-hybrid system to screen for proteins that interact with the PDZ domains of human X11alpha, and we isolated a clone encoding domains II and III of the copper chaperone for Cu,Zn-superoxide dismutase-1 (CCS). The X11alpha/CCS interaction was confirmed in coimmunoprecipitation studies plus glutathione S-transferase fusion protein pull-down assays and was shown to be mediated via PDZ2 of X11alpha and a sequence within the carboxyl terminus of domain III of CCS. CCS delivers the copper cofactor to the antioxidant superoxide dismutase-1 (SOD1) enzyme and is required for its activity. Overexpression of X11alpha inhibited SOD1 activity in transfected Chinese hamster ovary cells which suggests that X11alpha binding to CCS is inhibitory to SOD1 activation. X11alpha also interacts with another copper-binding protein found in neurons, the Alzheimer's disease amyloid precursor protein. Thus, X11alpha may participate in copper homeostasis within neurons.

Phosphorylation of thr(668) in the cytoplasmic domain of the Alzheimer's disease amyloid precursor protein by stress-activated protein kinase 1b (Jun N-terminal kinase-3)

Threonine(668) (thr(668)) within the carboxy-terminus of the Alzheimer's disease amyloid precursor protein (APP) is a known in vivo phosphorylation site. Phosphorylation of APPthr(668) is believed to regulate APP function and metabolism. Thr(668) precedes a proline, which suggests that it is targeted for phosphorylation by proline-directed kinase(s). We have investigated the ability of four major neuronally active proline-directed kinases, cyclin dependent protein kinase-5, glycogen synthase kinase-3 beta, p42 mitogen-activated protein kinase and stress-activated protein kinase-1b, to phosphorylate APPthr(668) and report here that SAPK1b induces robust phosphorylation of this site both in vitro and in vivo. This finding provides a molecular framework to link cellular stresses with APP metabolism in both normal and disease states.

p35/cdk5 binds and phosphorylates beta-catenin and regulates beta-catenin/presenilin-1 interaction

The neuronal cyclin-dependent kinase p35/cdk5 comprises a catalytic subunit (cdk5) and an activator subunit (p35). To identify novel p35/cdk5 substrates, we utilized the yeast two-hybrid system to screen for human p35 binding partners. From one such screen, we identified beta-catenin as an interacting protein. Confirmation that p35 binds to beta-catenin was obtained by using glutathione S-transferase (GST)-beta-catenin fusion proteins that interacted with both endogenous and transfected p35, and by showing that beta-catenin was present in p35 immunoprecipitates. p35 and beta-catenin also displayed overlapping subcellular distribution patterns in cells including neurons. Finally, we demonstrated that p35/cdk5 phosphorylates beta-catenin. beta-catenin also binds to presenilin-1 and altered beta-catenin/presenilin-1 interactions may be mechanistic in Alzheimer's disease (AD). Abnormal p35/cdk5 activity has also been suggested to contribute to AD. We therefore investigated how modulation of p35/cdk5 activity influenced beta-catenin/presenilin-1 interactions. Inhibition of p35/cdk5 with roscovitine did not alter the steady state levels of either beta-catenin or presenilin-1 but reduced the amount of presenilin-1 bound to beta-catenin. Thus, p35/cdk5 binds and phosphorylates beta-catenin and regulates its binding to presenilin-1. The findings reported here therefore provide a novel molecular framework to connect p35/cdk5 with beta-catenin and presenilin-1 in AD.

Fe65 and X11beta co-localize with and compete for binding to the amyloid precursor protein

The Fe65s and X11s are two families of adaptor proteins that bind to the Alzheimer's disease amyloid precursor protein (APP). Although both the X11s and Fe65s bind to similar regions of APP, they have opposing effects on Abeta production and hence may represent novel therapeutic targets. However, there is no evidence that the Fe65s and X11s are present within the same cell type or cell compartment and are thus capable of competing for binding to APP. Here we show that in neurones and transfected cells, APP, Fe65 and X11beta show overlapping subcellular distributions. Furthermore, we demonstrate that Fe65 and X11beta compete for binding to APP.

X11 alpha and x11 beta interact with presenilin-1 via their PDZ domains

X11 alpha and X11 beta are two neuronal adaptor proteins that interact with the Alzheimer's disease amyloid precursor protein (APP). X11 alpha and X11 beta stabilise APP and inhibit production of proteolytic APP fragments including the A beta peptide that is deposited in the brains of Alzheimer's disease patients. The mechanisms by which X11 alpha and X11 beta modulate APP processing are not clear but one possibility is that they influence the activity of the secretases that cleave APP to give rise to A beta. Presenilin-1 is required for gamma-secretase activity and here we demonstrate that both X11 alpha and X11 beta interact with presenilin-1. X11/presenilin-1 binding is via two X11 PDZ domains and sequences within the carboxy-terminus of presenilin-1. We also demonstrate that both X11 alpha and X11 beta mediate the formation of complexes between APP and presenilin-1. These results suggest that the X11 regulation of APP processing is controlled, at least in part, via their interactions with APP and presenilin-1.

Metabolic abnormalities associated with skeletal myopathy in severe anorexia nervosa

The aim of this study was to characterize the metabolic disturbance associated with the skeletal myopathy resulting from extreme weight loss in anorexia nervosa. Muscle function was examined in eight female patients with severe (40%) weight loss due to anorexia nervosa and histologically confirmed myopathy. A wide range of biochemical and hematologic investigations were carried out, including serum enzymes and the response of plasma lactate to ischemic exercise of forearm muscles. All patients showed proximal muscular weakness. A diminished lactate response to ischemic exercise was a consistent finding, and a reduction of serum carnosinase activity was also found. There were no other consistent biochemical or hematologic abnormalities apart from lymphopenia of no clinical consequence. These findings contribute to our understanding of severe protein-energy malnutrition on the musculoskeletal system. The resulting disorder is a metabolic myopathy from which the patients recover rapidly as their nutrition improves. Although the patients admitted to a variety of abnormal eating behaviors, no correlation was found between a specific type of abnormal eating behavior and subsequent biochemical abnormalities. Reinstating appropriate eating behavior will treat the myopathy.

Carnitine levels in patients with skeletal myopathy due to anorexia nervosa before and after refeeding

OBJECTIVE

To assess the role of carnitine in the skeletal myopathy present in anorexia nervosa.

METHOD

Serum levels of free and total carnitine were measured in a group of severely underweight women with anorexia nervosa and skeletal myopathy before and after an inpatient refeeding program.

RESULTS

Carnitine levels were within the reference range before refeeding and remained unchanged despite significant weight gain in all the subjects.

CONCLUSION

These findings suggest that carnitine plays no part in the muscle weakness seen in severe anorexia nervosa.

Mint2/X11-like colocalizes with the Alzheimer's disease amyloid precursor protein and is associated with neuritic plaques in Alzheimer's disease

Aberrant metabolism of the amyloid precursor protein (APP) is believed to be at least part of the pathogenic process in Alzheimer's disease. The carboxy-terminus of APP has been shown to interact with the Mint/X11 family of phosphotyrosine binding (PTB) domain-bearing proteins. It is via their PTB domains that the Mints/X11s bind to APP. Here we report the cloning of full-length mouse Mint2 and demonstrate that in primary cortical neurons, Mint2 and APP share highly similar distributions. Mint2 also colocalizes with APP in transfected CHO cells. In Mint2/APP-cotransfected cells, Mint2 reorganizes the subcellular distribution of APP and also increases the steady-state levels of APP. Finally, we demonstrate that Mint2 is associated with the neuritic plaques found in Alzheimer's disease but not with neurofibrillary tangles. These results are consistent with a role for Mint2 in APP metabolism and trafficking, and suggest a possible role for the Mints/X11s in the pathogenesis of Alzheimer's disease.

Capillary electrophoretic study of the complex formation between DNA and cationic surfactants

Due to the growing interest in the use of cationic surfactants for the construction of liposomal genetic delivery systems, the study of complex formation between DNA and quaternary ammonium detergents is of fundamental importance. In this context, we undertook the study of this complex formation using capillary zone electrophoresis (CZE) with suppressed electroosmotic flow, a technique that allowed us to both monitor the change in mobility of DNA as a function of added surfactant in a precise and reproducible manner and evaluate the potential of CZE to reflect the change in hydrodynamic friction upon binding. Nevertheless, CZE must be applied with caution for binding studies where strong cooperativity occurs, because of the presence of peak splitting at concentrations close to the half-point of binding. Also, a comparison between this experiment and Manning's polyelectrolyte transport properties theory on one hand and Tirado and Garcia de la Torre expression for hydrodynamic friction of rod-like molecules on the other hand is given.

Structural and functional changes in skeletal muscle in anorexia nervosa

Protein-energy malnutrition in anorexia nervosa is an under-recognised cause of muscle dysfunction. To characterise the skeletal myopathy that occurs in patients with severe anorexia nervosa, muscle function and structure were comprehensively examined in eight young adult female patients with severe (40%) self-induced weight loss. All of the patients showed impaired muscle function on strength and exercise measurement. The maximum voluntary contraction force for the patient group was significantly less than predicted values. Electromyography revealed myopathy in five of the patients, four of whom also had electro-physiological evidence of neuropathy. However, muscle biopsy specimens consistently showed myopathic changes with severe type 2 fibre atrophy but with no evidence of neuropathic changes. Ultrastructurally, there was separation and segmental loss of myofibrils and most biopsy samples contained abundant glycogen granules; we have previously reported that one of the most consistent biochemical abnormalities in these patients is impaired ischaemic lactate responses to forearm exercise. The result of severe protein-energy malnutrition on the musculo-skeletal system is a metabolic myopathy. Although the patients admitted to a variety of abnormal dieting behaviours, such as over-exercising and self-induced vomiting, no association was found between any of these and quantitative histological changes in the muscle biopsy samples. It is recommended that myopathy in anorexia nervosa be treated by instituting an appropriate refeeding programme.

Cyclin D2 interacts with cdk-5 and modulates cellular cdk-5/p35 activity

Cyclin-dependent kinase-5 (cdk-5) is a serine/threonine kinase that displays neurone-specific activity. Experimental manipulation of cdk-5 expression in neurones has shown that cdk-5 is essential for proper development of the nervous system and, in particular, for outgrowth of neurites. Such observations suggest that cdk-5 activity must be tightly controlled during development of the nervous system. To identify possible regulators of cdk-5, we used the yeast two-hybrid system to search for proteins that interact with cdk-5. In two independent yeast transformation events, cyclin D2 interacted with cdk-5. Immunoprecipitation experiments confirmed that cyclin D2 and cdk-5 interact in mammalian cells. Cyclin D2 did not activate cdk-5 as assayed using three different substrates, which was in contrast to a known cdk-5 activator, p35. However, cyclin D2 expression led to a decrease in cdk-5/p35 activity in transfected cells. As cyclin D2 and cdk-5 are known to share overlapping patterns of expression during development of the CNS, the results presented here suggest a role for cyclin D2 in modulating cdk-5 activity in postmitotic developing neurones.

Apolipoprotein E: non-cognitive symptoms and cognitive decline in late onset Alzheimer's disease

OBJECTIVES

To determine the association between the epsilon2 and epsilon4 alleles of apolipoprotein E (ApoE) and independent measures of cognitive decline and non-cognitive symptomatology in late onset Alzheimer's disease.

METHODS

The frequency of the epsilon2 and epsilon4 alleles of ApoE and their association with measures of cognitive decline and non-cognitive symptomatology were assessed in a population based case register study of 164 patients with late onset Alzheimer's disease from the east Lambeth and south Southwark districts of south London.

RESULTS

Analysis of a wide range of non-cognitive symptoms against ApoE epsilon4 genotype showed no significant association but a positive relation was found between ApoE epsilon2 genotype and depressive symptomatology (P = 0.004). No relation was found between measurements of cognitive decline and the presence of the ApoE epsilon4 allele. A trend for decreasing age at onset of 3 to 4 years in carriers of the ApoE epsilon4 allele was found, confirming earlier studies.

CONCLUSION

Presence of the epsilon4 allele of ApoE is associated with an earlier age at onset but does not seem to be related to either a more severe psychopathology or a more rapid progression of the illness. The epsilon2 allele of ApoE is associated with depressive symptomatology in late onset Alzheimer's disease.

The intracellular cytoplasmic domain of the Alzheimer's disease amyloid precursor protein interacts with phosphotyrosine-binding domain proteins in the yeast two-hybrid system

We have used the yeast two-hybrid system to screen for proteins that interact with the carboxy-terminal domain of APP. Six different clones were isolated and sequence analyses revealed that they encoded domains of a previously described neuronal protein Fe65, a homologue of Fe65 and a homologue of protein X11. All of these proteins contain one or more phosphotyrosine binding (PTB) domains. PTB domain proteins bind to the sequence Asn-Pro-X-Tyr when the Tyr is phosphorylated and are believed to function in signal transduction. APP contains such a motif. These results are consistent with a role for APP in signal transduction mechanisms.

Carer informants for dementia sufferers: carer awareness of cognitive impairment in an elderly community-resident sample

By comparing data obtained from the carers of 170 community-resident dementia sufferers with the results of objective cognitive testing, we assessed carer awareness of a range of cognitive deficits in their dependents. Spouses living with demented patients were the best at estimating the overall severity of cognitive impairment, whereas both first-degree (particularly if living with the dementia sufferer) and second-degree relatives were better at identifying and reporting the severity of memory impairment and topographical disorientation. Only one carer was aware of problems with object recognition, although a definite problem was detected in at least 40% of the study group. The testing instruments used (MMSE and CAMCOG) probably under-detected dysnomia and appeared to be inconclusive when compared with carer reports of difficulties that could be attributable to dyspraxia, highlighting the problem of sole reliance on either these instruments or informant accounts to obtain accurate clinical information.

The differential diagnosis of dementia

Dementia is misdiagnosed in up to 15% of cases referred for further assessment. Real or apparent cognitive impairment is usually a prominent clinical feature of the most common differential diagnoses, including normal aging, depression, nonaffective psychoses, delirium, and amnestic syndromes. To date, no practical biological marker exists to aid in diagnosing dementia. However, other conditions that are frequently amenable to treatment can usually be differentiated from dementia following detailed clinical assessment and the use of appropriate diagnostic criteria. Some considerations that aid in distinguishing dementia from other conditions include: rates of onset and progression; duration of symptoms; fluctuations in the intensity and pattern of symptoms; the pattern and extent of cognitive impairment and its effect on activities of daily living; alterations in the level of consciousness; the presence of affective and psychotic symptoms; past medical, family, and psychiatric history, including information about current medications, substance abuse, and premorbid personality.

Central serotonergic hyperresponsivity in late-onset Alzheimer's disease

The prolactin response to oral d-fenfluramine (30 mg) was measured in nine patients with late-onset Alzheimer's disease and in an elderly comparison group. The serotonin-mediated prolactin response was significantly greater in the patients with Alzheimer's disease than in the comparison group. This finding suggests that central serotonin responsivity is greater in Alzheimer's disease.