Association between in vivo fluorine 18-labeled flutemetamol amyloid positron emission tomography imaging and in vivo cerebral cortical histopathology

OBJECTIVE

To determine the correspondence of in vivo quantitative estimates of brain uptake of fluorine 18-labeled flutemetamol with immunohistochemical estimates of amyloid levels in patients who underwent previous biopsy.

DESIGN

Cross-sectional study of ¹⁸F-flutemetamol positron emission tomography (PET) findings in patients with prior cortical biopsy specimen stained for the presence or absence of amyloid plaques.

SETTING

University hospital. Patients Seven patients who previously had a prior right frontal cortical biopsy at the site of ventriculoperitoneal placement for presumed normal pressure hydrocephalus were recruited. Inclusion criteria included an adequate biopsy specimen for detection and quantification of β-amyloid pathology and age older than 50 years. Intervention All patients underwent an ¹⁸F-flutemetamol PET scan.

MAIN OUTCOME MEASURES

Quantitative measures of ¹⁸F-flutemetamol uptake (standardized uptake value ratio, a ratio of mean target cortex activity divided by that in a cerebellar reference region) were made at a location contralateral to the biopsy site and compared with estimates of amyloid load based on immunohistochemical and histological staining.

RESULTS

There was complete agreement between visual reads of ¹⁸F-flutemetamol PET scans (3 blinded readers with majority rule) and histology. A regression model, including time from biopsy as a covariate, demonstrated a significant relationship (P = .01) between ¹⁸F-flutemetamol uptake and percentage of area of amyloid measured by a monoclonal antibody raised against amyloid (NAB228). Similar results were found with the amyloid-specific monoclonal antibody 4G8 and Thioflavin S.

CONCLUSION

To our knowledge, these data are the first to demonstrate the concordance of ¹⁸F-flutemetamol PET imaging with histopathology, supporting its sensitivity to detect amyloid and potential use in the study and detection of Alzheimer disease.

18F-flutemetamol amyloid imaging in Alzheimer disease and mild cognitive impairment: a phase 2 trial

OBJECTIVE

The most widely studied positron emission tomography ligand for in vivo beta-amyloid imaging is (11)C-Pittsburgh compound B ((11)C-PIB). Its availability, however, is limited by the need for an on-site cyclotron. Validation of the (18)F-labeled PIB derivative (18)F-flutemetamol could significantly enhance access to this novel technology.

METHODS

Twenty-seven patients with early-stage clinically probable Alzheimer disease (AD), 20 with amnestic mild cognitive impairment (MCI), and 15 cognitively intact healthy volunteers (HVs) above and 10 HVs below 55 years of age participated. The primary endpoint was the efficacy of blinded visual assessments of (18)F-flutemetamol scans in assigning subjects to a raised versus normal uptake category, with clinical diagnosis as the standard of truth (SOT). As secondary objectives, we determined the correlation between the regional standardized uptake value ratios (SUVRs) for (18)F-flutemetamol and its parent molecule (11)C-PIB in 20 of the AD subjects and 20 of the MCI patients. We also determined test-retest variability of (18)F-flutemetamol SUVRs in 5 of the AD subjects.

RESULTS

Blinded visual assessments of (18)F-flutemetamol scans assigned 25 of 27 scans from AD subjects and 1 of 15 scans from the elderly HVs to the raised category, corresponding to a sensitivity of 93.1% and a specificity of 93.3% against the SOT. Correlation coefficients between cortical (18)F-flutemetamol SUVRs and (11)C-PIB SUVRs ranged from 0.89 to 0.92. Test-retest variabilities of regional SUVRs were 1 to 4%.

INTERPRETATION

(18)F-Flutemetamol performs similarly to the (11)C-PIB parent molecule within the same subjects and provides high test-retest replicability and potentially much wider accessibility for clinical and research use.

Regional survey of tuberculosis risk assessment in rheumatology outpatients commencing anti-TNF-alpha treatment in relation to British Thoracic Society guidelines

The aim of this study was to analyse tuberculosis (TB) risk assessment for rheumatology patients commencing anti-tumour necrosis factor-alpha (anti-TNF-alpha) therapy using the British Thoracic Society (BTS) guidelines. Data were obtained retrospectively on 856 outpatients regionally receiving anti-TNF-alpha. Prior to commencing treatment, patients had the following assessments documented: respiratory examination, 47.4%; chest X-ray, 84.5%; TB history, 92.9%; and advice about TB risk, 45.8%. Of the 856 patients, 94.3% were on immunosuppressives but 27% had a tuberculin test; 12.6% had > or =1 high-risk factors for TB. In total, 3.4% were referred to a TB specialist and of these, 24.1% had no risk factors for TB. Of patients with > or =1 risk factor, 76.9% were not referred. Only 4/28 patients at high risk for TB due to ethnicity or birthplace received chemoprophylaxis. Marked inter-unit variation was demonstrated and it was evident that patients require improved screening for TB. Greater awareness is necessary of patients with risk factors, particularly ethnicity, to facilitate more appropriate targeting of chemoprophylaxis. Multi-centre audit is a valuable clinical governance tool.

Selecting sanitation systems for sustainability in developing countries

This paper presents a methodology for systematically incorporating multi-dimensional sustainability considerations into the selection of wastewater options for developing countries and the evaluation and comparison of these options. Appropriate technologies for developing countries were screened based on their function and their use of operational sustainability features; this list of technologies can then be used to elaborate design options. Sustainability indicators are used to enable a parallel comparison of the options from environmental, economic, and socio-cultural perspectives. For illustration, the indicator approach is applied to a case study of the sanitation options for peri-urban/rural areas of the eThekwini Municipality in South Africa.

Experience with highly purified porcine factor VIII in a patient with haemophilia A and a factor VIII inhibitor

Highly purified porcine factor VIII has been advocated for the treatment of bleeding episodes in patients with haemophilia who have inhibitors to factor VIII. This approach has been successful in a patient with an intermediate potency inhibitor showing little cross-reactivity to porcine material. As in some other reported cases, a severe allergic reaction occurred on one occasion but did not preclude the subsequent use of the porcine concentrate in carefully controlled conditions.

Challenges with up-scaling dry sanitation technologies

The acceleration of sanitation delivery towards meeting the South African Government's target of completely eradicating the existing backlogs by 2010, has led to a surge of activities. As part of its strategy for ensuring that basic sanitation is provided, the policy has recommended that a ventilated improved pit latrine (VIP) is considered as the basic minimum requirement in the form of a sanitation technology. The up-scaling and delivering of sanitation in many cases in the form of VIPs and its derivatives, as well as urine diversion technology are beginning to pose many technical challenges. The principles on which they have been designed are not always being observed in practice. As a result, some systems are filling up much faster than expected. Research has found that the breakdown in the faeces is not happening as would be expected in an anaerobic reactor, and that the drying of faeces in humid conditions, even with the use of drying agents, is not optimum. These problems, which are being experienced in the field, will have long term repercussions on the sustainability of sanitation provision. This paper aims to share these experiences and findings of research, and the impact it may have on the Sanitation MDG goals.

Etanercept: effective in the management of hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic suppurative condition which is poorly responsive to treatment and is characterized by significant morbidity. Successful treatment of HS in patients treated with infliximab for concomitant Crohn's disease has been reported. More recent reports of positive responses to infliximab [an antitumour necrosis factor (TNF)-alpha agent] in patients who have HS but not Crohn's disease are encouraging.

OBJECTIVES

TNF-alpha is implicated in many inflammatory disorders and we wished to determine the efficacy of subcutaneous etanercept, a competitive inhibitor of TNF-alpha in the control of HS symptoms.

METHODS

We commenced six patients with severe, recalcitrant HS on etanercept (25 mg subcutaneously twice weekly in all cases). All patients had a normal chest X-ray and negative purified protein derivative test prior to treatment and were closely monitored throughout the treatment period for signs of infection. Patients self-assessed their disease activity and completed Dermatology Life Quality Index (DLQI) questionnaires immediately before the introduction of therapy and 24 weeks later in the case of four patients, and 12 weeks later in the case of two others. All patients were asked to estimate the time lapse between commencement of treatment and initial response.

RESULTS

Treatment was well tolerated by all patients with no reported adverse reactions. A marked reduction in self-reported disease activity (mean reduction of 61% at 24 weeks), in DLQI scores (mean reduction of 64% at 24 weeks) and in relapse rates occurred. All patients rated etanercept as their most effective treatment to date.

CONCLUSIONS

Our results show the effectiveness of etanercept in this group of patients with particularly challenging disease. Etanercept, unlike infliximab, may be administered subcutaneously, rendering costly day-case admissions unnecessary.

Mutation analysis in Irish families with glomuvenous malformations

BACKGROUND

Glomuvenous malformations (GVMs) are rare bluish lesions that can affect the skin and mucosal surfaces. They represent defects in vasculogenesis. Lesions can occur sporadically or in an autosomal dominant mode of inheritance. Recent studies have shown that mutations in the glomulin gene (GLMN) on chromosome 1p21-22 are responsible for familial GVMs.

OBJECTIVES

To search for mutations in GLMN in Irish families with GVMs.

METHODS

We identified four Irish families with GVMs and confirmed linkage to chromosome 1p21-22 in these cases. We sequenced the glomulin gene in all affected and unaffected members of the families. Results Linkage analysis showed that affected individuals from the families shared a common haplotype. Mutation analysis revealed a delAAGAA mutation in exon 3 of the glomulin gene in all four families with GVMs.

CONCLUSIONS

We confirm that mutations in the glomulin gene are responsible for GVMs and suggest a founder Irish mutation in the glomulin gene in four Irish families.

CD molecules 2005: human cell differentiation molecules

The immune system works through leukocytes interacting with each other, with other cells, with tissue matrices, with infectious agents, and with other antigens. These interactions are mediated by cell-surface glycoproteins and glycolipids. Antibodies against these leukocyte molecules have provided powerful tools for analysis of their structure, function, and distribution. Antibodies have been used widely in hematology, immunology, and pathology, and in research, diagnosis, and therapy. The associated CD nomenclature is commonly used when referring to leukocyte surface molecules and antibodies against them. It provides an essential classification for diagnostic and therapeutic purposes. The most recent (8th) Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA), held in Adelaide, Australia, in December 2004, allocated 95 new CD designations and made radical changes to its aims and future operational strategy in order to maintain its relevance to modern human biology and clinical practice.

Bayesian variable selection in multinomial probit models to identify molecular signatures of disease stage

Here we focus on discrimination problems where the number of predictors substantially exceeds the sample size and we propose a Bayesian variable selection approach to multinomial probit models. Our method makes use of mixture priors and Markov chain Monte Carlo techniques to select sets of variables that differ among the classes. We apply our methodology to a problem in functional genomics using gene expression profiling data. The aim of the analysis is to identify molecular signatures that characterize two different stages of rheumatoid arthritis.

Microbiological studies of an anaerobic baffled reactor: microbial community characterisation and deactivation of health-related indicator bacteria

This WRC funded project has studied the appropriateness of the ABR (anaerobic baffled reactor) for on-site primary sanitation in low-income communities. A 3,000 L pilot reactor was located at the Kingsburgh wastewater treatment plant south of Durban, South Africa. Feed to the reactor was raw domestic wastewater containing a significant proportion of particulate organic matter. The compartments of the ABR were routinely monitored for pH, COD, and gas production, among other physical-chemical determinants. The microbial population in each compartment was analysed by fluorescent in situ hybridisation, using general oligonucleotide probes for eubacteria and archeae and a suite of 10 genera or family specific probes. Scanning electron microscopy was conducted on the sludge fraction of each compartment. Mixed fractions from each compartment were also analysed for health-related indicator bacteria (total coliforms and E. coli). Results indicated that methanogenesis was not occurring to the expected extent in the latter compartments, and that this was probably due to a hydraulic load limitation. This contrasted with earlier studies on industrial effluent, for which the organic load was exclusively in soluble form. Inactivation of health-related indicator bacteria was less than 1 log, indicating the need for an additional post-treatment of the effluent to protect community health.

Non spiral and spiral (helical) flow patterns in stenoses. In vitro observations using spin and gradient echo magnetic resonance imaging (MRI) and computational fluid dynamic modeling

AIM

Physiological blood flow patterns are themselves poorly understood despite their impact on arterial disease. Stable spiral (helical) laminar flow (SLF) has been observed in normal subjects. The purpose of the present study is to develop a method of magnetic resonance (MR) flow pattern visualization and to analyze spiral and non-spiral flow patterns with and without luminal narrowing in vitro. The flow conditions were then modeled using computational fluid dynamics (Star-CD).

METHODS

Laminar integrity was examined in a flow-rig using spin and gradient echo magnetic resonance imaging (MRI) in non-stenosed and stenosed conduits in the presence of non-spiral and spiral flow.

RESULTS

No difference was observed in a non-stenosed conduit between non-spiral and spiral flow. In the presence of a stenosis spiral flow preserves flow velocity coherence whereas non-spiral flow increasingly lost coherence beginning proximal to the stenosis. Computational fluid dynamic modeling of the in vitro experiment showed marked differences between the 2 flow patterns. Non-spiral flow produced greater inwardly directed forces just beyond the stenosis and greater outward pressures at more distal sites. The near wall turbulent energy was up to 700% less with spiral flow over non-spiral flow beyond the stenosis.

CONCLUSIONS

Spiral flow appears to offer clear flow profile stabilizing advantages over non-spiral flow, by significantly reducing the turbulence caused by a stenosis. Spiral flow also produces lower forces acting on the vessel wall.

Fast emulsion droplet sizing using NMR self-diffusion measurements

Emulsion droplet sizing using pulsed field gradient (PFG) nuclear magnetic resonance (NMR) is a well-established technique. Traditionally these measurements require total acquisition times of typically 5-20 min per sample, which severely limits our ability to use this method to study dynamic processes. Here we present the application and verification of an NMR pulse sequence, Difftrain, which enables emulsion droplet size distributions to be measured in 3-10 s. We have previously introduced applications of Difftrain (C. Buckley, K.G. Hollingsworth, A.J. Sederman, D.J. Holland, M.L. Johns, L.F. Gladden, J. Magn. Reson. 161 (2003) 112-117), including the droplet sizing of a single unimodal emulsion sample. In this paper, several model emulsions containing different oils are measured and the results compared directly with sizing provided by laser scattering. In this manner, the Difftrain method is verified and its possibilities and limitations are explored. Guidelines are proposed for the range of droplet sizes for which accurate results can be produced. The Difftrain technique opens up the possibility of studying non-equilibrium emulsions; a study of the in situ emulsification of a 21% v/v water-in-silicone oil emulsion is presented.

Transendothelial migration confers a survival advantage to activated T lymphocytes: role of LFA-1/ICAM-1 interactions

The clearance of activated T lymphocytes by apoptosis is an essential component in the resolution of the immune response; however, certain signals received within inflamed tissue may result in the persistence of activated T cells. Our previous work has shown that, when compared with resting cells, effector cells migrate more efficiently across endothelium, thus such cells may be selectively recruited to sites of inflammation. We hypothesized that transmigration of T cells across endothelium might influence cell survival. We have generated T cell lines by culturing in IL-2 following PHA activation. These T cell lines die rapidly by apoptosis when deprived of IL-2 (53.7 +/- 4.0% survival after 24 h). In contrast, cells that have migrated across human umbilical vein endothelial cells (HUVEC) survived significantly better than control cells (80.3 +/- 3.6%, n= 18, P<0.001). Endothelial cell conditioned medium was also able to reduce apoptosis, but this effect was small when compared with the protective effect of transmigration. Culture of T lymphocytes on fibronectin, or RGD peptides, or in suspension with a range of chemokines active on T cells, including RANTES and lymphotactin had no effect on survival. In contrast, blocking LFA-l/ICAM-l interactions reduced the protective effect of transmigration (42.3 +/- 6.7% reduction). Culture of activated T cells on immobilized ICAM-l alone also increased survival. These results indicate that signals received by activated T cells during extravasation can influence their subsequent survival within tissue, and implicates the involvement of LF A-l/ICAM-l interactions.

Evidence of underdiagnosis of myasthenia gravis in older people

BACKGROUND

Myasthenia gravis is a potentially serious but treatable muscle disease caused by autoantibodies directed at the acetylcholine receptor (AChR) on the postsynaptic membrane of the neuromuscular junction. There is anecdotal evidence that the diagnosis is sometimes missed in older patients.

OBJECTIVE

To examine the incidence and age distribution of positive AChR antibodies in samples referred to diagnostic laboratories in the UK, and the prevalence of positive AChR antibodies in samples from a cohort of older individuals.

METHODS

Positive AChR antibody tests were identified from all UK centres registered for the assay with the European quality assurance scheme (EQAS) during 1997-99, and the age and sex specific incidence was calculated, based on the UK population. The prevalence of AChR antibodies in sera from a sample of 2000 individuals aged > or =60 years was determined.

RESULTS

3183 individuals had positive AChR antibody tests on routine screening during the years 1997 to 1999 in the UK, giving an annual incidence of 1.8/100 000. In both sexes, the age specific incidence rose steeply between the ages of 45 and 74, reaching 9.9/100 000 in men, and then fell, with a sharp decline above the age of 80. In the prevalence study, whereas only one serum from individuals aged 60-74 years was positive for AChR antibodies (0.12%), sera from eight individuals aged > or =75 years were positive (0.7%). Only one had a previous clinical diagnosis of myasthenia gravis but four others had histories of stroke or transient ischaemic attacks.

CONCLUSIONS

The sharp fall in the incidence of clinically recognised myasthenia gravis in people over 80 years of age in our national AChR antibody incidence study, and the high prevalence of previously unrecognised positive AChR antibodies in those > or =75 years old, suggest that myasthenia gravis may be substantially underdiagnosed in older people.

Applications of fast diffusion measurement using Difftrain

Novel applications of fast self-diffusion measurement are presented. Difftrain (Diffusion train), which uses successive stimulated echoes from a single excitation pulse where a portion of the available magnetisation is recovered for each echo, is used to measure self-diffusion by varying the observation time. It is applied to produce the droplet size distribution of an oil-in-water emulsion in less than 4s. This is verified by comparison with the droplet size distribution produced by a standard pulsed field gradient (PFG) technique. Difftrain is also extended to enable the application of incremental gradients, in addition to varying the observation time. This is used to produce propagators or displacement probabilities of water flowing through a packed bed for a range of 16 observation times in under 10 min. Again verification is provided by acquisition of the same propagators using a conventional PFG technique.

A new calcipotriol/betamethasone formulation with rapid onset of action was superior to monotherapy with betamethasone dipropionate or calcipotriol in psoriasis vulgaris

In this study, we compared a new combination ointment containing both calcipotriol and betamethasone dipropionate with betamethasone dipropionate ointment (Diprosone) and calcipotriol ointment (Daivonex) in patients with psoriasis vulgaris; 1106 patients were randomized to twice daily double-blind treatment with combination, betamethasone dipropionate or calcipotriol for 4 weeks. Patients then received twice daily calcipotriol, unblinded, for a further 4 weeks. Mean percentage change in PASI at end of the double-blind phase was -74.4 (combination group), -61.3 (betamethasone group) and -55.3 (calcipotriol group). Mean difference (95% Cl) combination-betamethasone was -13.1 (-16.9 to -9.3, p < 0.001) and for combination-calcipotriol -19.0 (-22.8 to -15.2, p <0.001). The differences in PASI were also statistically significant after 1 week. In the double-blind phase, 8.1% of patients (combination) reported lesional/ perilesional adverse reactions compared to 4.7% (betamethasone) and 12.0% (calcipotriol). In the combination group, mean PASI at the end of the double-blind phase was 2.5, and at end of the unblinded phase 3.6, compared with 3.9 and 4.1 (betamethasone) and 4.4 and 3.7 (calcipotriol). Calcipotriol/betamethasone combination is more effective and has a more rapid onset of action than either active constituent used alone, and is well tolerated. It is safe to transfer patients from combination to calcipotriol, with maintenance of clinical effect.

Symptom response after palliative radiotherapy for patients with brain metastases

Whole brain radiotherapy (RT) is frequently used to palliate symptoms in patients with brain metastases, but the palliative benefit to patients has not been well documented. We conducted a longitudinal observational prospective study of patients receiving standard RT (20 Gray (Gy)/5 fractions) for symptomatic brain metastases. End-points were observer rating of neurological symptoms, patient-rated symptoms, performance status, neurological functional status, cognitive function and quality of life (QOL). Median survival for the 75 patients was 86 days (95% confidence interval (CI): 65-101 days). At 1 month, 19% of patients showed an improvement or resolution of presenting symptoms, 23% were stable and 55% had progressed or died. Patient-rated symptoms were increased at 1 month in comparison to baseline data. Only 4 patients had an improved performance status and 22 were stable. Many patients with brain metastases have a short life expectancy and may not benefit from even short duration radiation schedules. Further effort is needed to optimise patient selection and tailor treatment appropriately.

Water and wastewater in developing countries: present reality and strategy for the future

This paper summarises the paper presentation sessions at the Conference, as well giving insights on the issues related to developing countries. It also discusses the present status of practice and research on water and wastewater management, and projected future scenario based not only on the papers presented in the Conference, but also on other sources. The strategy is presented to overcome many problems in developing countries such as rapid urbanization, industrialization, population growth, financial and institutional problems and, depleting water resources. The strategy consists of Integrated Urban Water Management (IUWM), cleaner industrial production, waste minimisation and financial arrangements.

CD antigens 2001

The most recent Human Leucocyte Differentiation Antigen Workshop ("HLDA7") took place in 2000 in Harrogate, UK and the proceedings are about to be published (Leucocyte Typing VII). New Sections were introduced in this Workship (Dendritic cells, Stem/progenitor cells, Erythroid cells and Carbohydrate Structures) and monoclonal antibodies were selected for which at least some molecular data were already available (to avoid "blind" screening of reagents against known specificities). A total of more than 80 new CD specificities were established (previously the average was less than 30 new CD specificities per Workshop) and these are listed in this article. There is already evidence for the existence of many new leucocyte surface molecules for study at the next HLDA Workshop (in Adelaide in 2004), and we have listed in this article a number of such potential CD candidates (identified following the production of monoclonal antibodies or via gene cloning). There are also today an increasing number of lineage- and/or stage-restricted leucocyte-associated molecules localised within the cell cytoplasm (or nucleus): they will certainly prove of intense in the future for many laboratories studying human haematopoietic cells (regardless of whether a new "intracellular CD" categorisation scheme is devised for such molecules).

Do titin and cytokine antibodies in MG patients predict thymoma or thymoma recurrence?

BACKGROUND

Patients with MG often have other autoantibodies in addition to those against the acetylcholine receptor (AChR). It has been suggested that antibodies to the muscle protein titin may be diagnostic of a thymoma, but they have also been found in patients with late-onset MG. Antibodies to certain cytokines have also been detected in patients with MG and thymoma, and it is not clear whether these antibodies could be more useful clinically. The authors measured antibodies against titin and the cytokines interferon alpha (IFNalpha) and interleukin 12 (IL12) in patients with MG and thymoma or thymoma recurrence, and in patients with MG but without thymoma presenting before (early-onset MG) or after (late-onset MG) 40 years of age.

METHOD

Levels of titin, IFNalpha, and IL12 antibodies were determined by radioimmunoassay in 191 patients with MG and 82 controls.

RESULTS

As previously reported, titin antibodies were uncommon in patients with early-onset MG. However, in patients with late-onset MG, titin antibodies had similar prevalence and levels to those in patients with MG and thymoma, although the antibodies were uncommon in patients between 40 and 60 years of age presenting without a tumor. By contrast, cytokine antibodies were more common in patients with thymoma than in patients without thymoma, and cytokine antibodies typically increased substantially if the thymoma recurred.

CONCLUSIONS

Measurement of titin antibodies has limited use in predicting the presence of a tumor, unless the patient is less than 60 years of age, but measurement of IFNalpha and IL12 antibodies may be helpful in identifying patients with a thymoma recurrence, particularly when mediastinal imaging is equivocal.

CD antigens 2001

This paper reviews the Seventh Human Leucocyte Differentiation Antigen (HLDA7) workshop. Due to the limitations of "blind" antibody screening, which had been evident at the previous meeting in 1996, participants at HLDA7 adopted a more selective approach to the choice of antibodies by identifying new CD specificities. This resulted in the addition of more than 80 new CD specificities. Plans for the eighth and subsequent workshops are also previewed.

Potassium channel antibodies in two patients with reversible limbic encephalitis

Limbic encephalitis (LE) is often associated with lung, thymic, or testicular tumours and antibodies to Hu, CV2, or Ma2 (Ta) antigens. In these cases, it generally has a poor prognosis. Here we describe two patients with symptoms of LE, negative for typical paraneoplastic antibodies, in whom antibodies to voltage-gated potassium channels (VGKC) were detected retrospectively in serial serum samples. Patient 1 had a thymoma recurrence, but in patient 2 no tumour has been detected in the years following presentation. Plasma exchange was effective in reducing VGKC antibody levels, with substantial improvement in mental symptoms in patient 1. In patient 2, the VGKC antibodies fell spontaneously over two years, with almost complete recovery of mental function. Although neither patient had obvious neuromyotonia at presentation, both showed excessive secretions. We suggest that patients with limbic symptoms and excessive secretions should be tested for VGKC antibodies, and, if they are present, prompt and effective immunosuppressive treatment should be considered.